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CD117+CD3−CD56−OX40Lhigh cells express IL-22 and display an LTi phenotype in human secondary lymphoid tissues
Abstract
Here, we identify cells within human adult secondary lymphoid tissues that are comparable in phenotype and location to the lymphoid tissue inducer (LTi) cells that persist in the adult mouse. Identified as CD117(+) CD3(-) CD56(-) cells, like murine LTi cells, they lack expression of many common lineage markers and express CD127, OX40L and TRANCE. These cells were detected at the interface between the B- and T- zones, as well as at the subcapsular sinus in LNs, the location where LTi cells reside in murine spleen and LNs. Furthermore, like murine LTi cells, these cells expressed high levels of IL-22 and upregulated IL-22 expression upon IL-23 stimulation. Importantly, these cells were not an NK cell subset since they showed no expression of IFN-γ and perforin. Interestingly, a subset of the CD117(+) CD3(-) CD56(-) OX40L(+) population expressed NKp46, again similar to recent findings in mice. Finally, these cells supported memory CD4(+) T-cell survival in an OX40L-dependent manner. Combined, these data indicate that the CD117(+) CD3(-) CD56(-) OX40L(+) cells in human secondary lymphoid tissues are comparable in phenotype, location and function to the LTi cells that persist within adult murine secondary lymphoid tissues.
... LTi cells constitutively express IL-22 [7] and are located mainly in cryptopatches and Peyer's patches within the small intestine as well as in lymph nodes [8]. After birth, additional populations of Rorgt+ ILC appear, mostly in mucosal tissues, which are characterized by expression of natural cytotoxicity receptors (NCR); NKp46 in mice and NKp30, NKp44 and NKp46 in human [9][10][11][12][13][14][15][16]. In this review we will collectively refer to these NCR-expressing Rorgt+ ILC as NCR+ ILC. ...
... Rorgt+ ILC persist into adulthood in both mice [6,[10][11][12] and men [13,14,16] but are distinguished from the fetal population by their expression of not only high levels of OX40L in humans but also OX40L and CD30L in mice [14,22,23]. This expression has been associated with supporting memory CD4 T cell survival in specialized lymph node niches [24]. ...
... Rorgt+ ILC persist into adulthood in both mice [6,[10][11][12] and men [13,14,16] but are distinguished from the fetal population by their expression of not only high levels of OX40L in humans but also OX40L and CD30L in mice [14,22,23]. This expression has been associated with supporting memory CD4 T cell survival in specialized lymph node niches [24]. ...
... Immunofluorescence and image analysis. Tissue sections from experimental mice were cut and stained as described previously 13,44 . Briefly, 6-mm-thick sections of tissue were cut, fixed in cold acetone at 4°C for 20 min and then stored at À 20°C before staining. ...
... Antibodies raised against the following mouse antigens were used: CD3 (clone eBio500A2, 1:50, eBioscience), CD31 (clone 390, 1:200, eBioscience), CD169 (clone 3D6.112, 1:800, AbD Serotec), F4/80 (clone BM8, 1:50, eBioscience), GATA-3 (clone TWAJ, 1:25, eBioscience), ICOS (clone C398.4A, 1:25, Biolegend), IgM (1:200, Jackson ImmunoResearch), IL-7Ra (clone A7R34, 1:25, eBioscience), KLRG-1 (clone 2F1, 1:50, eBioscience), RANKL (clone IK22/5, 1:50, eBioscience) and RORg (clone AFKJS-9, 1:30, eBioscience). Detection of RORg and GATA-3 expression required amplification of the signal as described previously 44 . Purified rat primary antibodies against the transcription factors were detected with donkey antirat-IgG-FITC (1:150, Jackson ImmunoResearch), and then rabbit anti-FITC-AF488 (1:200, Life Technologies) and then with donkey anti-rabbit-IgG-AF488 (1:200, Life Technologies). ...
Presentation of peptide:MHCII by RORγ-expressing group 3 innate lymphoid cells (ILC3s), which are enriched within gut tissue, is required for control of CD4 T-cell responses to commensal bacteria. It is not known whether ILC populations migrate from their mucosal and peripheral sites to local draining secondary lymphoid tissues. Here we demonstrate that ILC3s reside within the interfollicular areas of mucosal draining lymph nodes, forming a distinct microenvironment not observed in peripheral lymph nodes. By photoconverting intestinal cells in Kaede mice we reveal constitutive trafficking of ILCs from the intestine to the draining mesenteric lymph nodes, which specifically for the LTi-like ILC3s was CCR7-dependent. Thus, ILC populations traffic to draining lymph nodes using different mechanisms.
... Additionally, our work has shown that LTi persist in adult lymphoid tissues in both mouse (36) and man (37), but are distinguished from the neonatal population by their expression of high levels of OX40-ligand (OX40L)(TNFSF4) (36, 37) and in mouse, CD30L(TNFSF8) (36). Our studies have found that CD4 T cell memory function is highly dependent on signaling through both OX40 and CD30 (38), suggesting additional roles for LTi in the mediation of adaptive CD4 dependent immune responses. ...
... Additionally, our work has shown that LTi persist in adult lymphoid tissues in both mouse (36) and man (37), but are distinguished from the neonatal population by their expression of high levels of OX40-ligand (OX40L)(TNFSF4) (36, 37) and in mouse, CD30L(TNFSF8) (36). Our studies have found that CD4 T cell memory function is highly dependent on signaling through both OX40 and CD30 (38), suggesting additional roles for LTi in the mediation of adaptive CD4 dependent immune responses. ...
Although current thinking has focused on genetic variation between individuals and environmental influences as underpinning susceptibility to both autoimmunity and cancer, an alternative view is that human susceptibility to these diseases is a consequence of the way the immune system evolved. It is important to remember that the immunological genes that we inherit and the systems that they control were shaped by the drive for reproductive success rather than for individual survival. It is our view that human susceptibility to autoimmunity and cancer is the evolutionarily acceptable side effect of the immune adaptations that evolved in early placental mammals to accommodate a fundamental change in reproductive strategy. Studies of immune function in mammals show that high affinity antibodies and CD4 memory, along with its regulation, co-evolved with placentation. By dissection of the immunologically active genes and proteins that evolved to regulate this step change in the mammalian immune system, clues have emerged that may reveal ways of de-tuning both effector and regulatory arms of the immune system to abrogate autoimmune responses whilst preserving protection against infection. Paradoxically, it appears that such a detuned and deregulated immune system is much better equipped to mount anti-tumor immune responses against cancers.
... By the interaction with OX40 and CD30-expressing CD4 T cells, LTi cells help memory CD4 T cell development (18). Recently, LTi cells were identified in human tissues such as tonsils and lymph nodes (23,24). However, the phenotype of the human cells is not exactly same to that of the murine cells, for example, human LTi cells do not express CD30L (25,26). ...
... Therefore, we examined whether LTi cells are present in human RA synovial fluid. Because human LTi cells are well described in tonsils (23,24), which are normal lymphoid tissues, we compared the immune cells infiltrate in RA synovial tissue with cells from tonsils as well as to immune cells infiltrated to synovial fluid in patients with osteoarthritis (OA), which is degenerative joint disease and the most common form of arthritis (27,28). Because the proportions of infiltrated lymphocytes and activated macrophages are different between different patients, we categorized three patient groups based on the proportion of macrophages in the synovial fluid: a macrophage-high group, which contained more than 80% macrophages; a macrophage-intermediate group, which contained between 40% and 80% macrophages, and a macrophage-low group, which contained less than 40% macrophages. ...
In this study, we compared the immune cell populations in rheumatoid arthritis (RA) synovial fluid, which shows lymphoid tissue-like structure, with those in tonsils, which are normal secondary lymphoid tissues. Firstly, we found that CD4(-)CD11b(+) macrophages were the major population in RA synovial fluid and that B cells were the major population in tonsils. In addition, synovial fluid from patients with osteoarthritis, which is a degenerative joint disease, contained CD4(+)CD11b(+) monocytes as the major immune cell population. Secondly, we categorized three groups based on the proportion of macrophages found in RA synovial fluid: (1) the macrophage-high group, which contained more than 80% macrophages; (2) the macrophage-intermediate group, which contained between 40% and 80% macrophages; and (3) the macrophage-low group, which contained less than 40% macrophages. In the macrophage-low group, more lymphoid tissue inducer (LTi)-like cells were detected, and the expression of OX40L and TRANCE in these cells was higher than that in the other groups. In addition, in this group, the suppressive function of regulatory T cells was downregulated. Finally, CXCL13 expression was higher in RA synovial fluid than in tonsils, but CCL21 expression was comparable in synovial fluid from all groups and in tonsils. These data demonstrate that increased lymphocyte infiltration in RA synovial fluid is correlated with an increase in LTi-like cells and the elevation of the chemokine expression.
... p=.000, respectively). In line with our result, kim et al. found a significant association between serum IL-22 and ACCP antibodies 37 . Of potential implication, the strong association of elevated serum IL-22 with the more specific serologic marker, ACCP antibodies. ...
Interleukin (IL)-22 is a novel mediator of a member of IL-10 family cytokines that is produced by many different types of lymphocytes including both those of innate and adaptive immune system. This cytokine has potent proliferative and inflammatory effects on different cell lines. Recently, accumulated data has indicated that IL-22 plays an important role in the pathogenesis of rheumatoid arthritis (RA). We aimed to investigate the levels of IL-22 and its association with demographic, clinical data as well as serological markers in RA. IL-22 serum levels were measured in 45 newly diagnosed RA patients without any treatment and 45 healthy individuals as control by a manual Enzyme linked immunosorbent assay (ELISA). Correlations of IL-22 serum levels were sought with demographic, clinical data and serological parameters. IL-22 levels were significantly elevated in serum of RA patients (median= 86.89ng/ml and range = 896) compared to serum of healthy control (median=75.36ng/ml and range=459), p=.022. The IL-22 levels were correlated positively with C-reactive protein (CRP), anti-cyclic citrullinated peptide (ACCP) antibodies in RA patients. Significant higher levels of serum IL-22 in RA patients compare with those in healthy control. Highly significant association between serum levels of IL-22 and the serological markers (CRP and ACCP antibodies) in the diagnosis of RA suggest the potential levels of IL-22 as a valuable biomarker for the evaluation of disease severity in RA patients. Cite this article-Dekra A. El-Aghbary, Safa'a M. Darwiesh, Khaled A. Al-Moyed. Interleukin-22 serum levels in patients with rheumatoid arthritis in Sana'a city, Yemen.
... A11090, Life Technologies, 1:100 in PBS/1% BSA), incubated at room temperature for 1 hour, followed by further amplification with donkey anti-rabbit IgG FITC conjugated to AF488 (no. A21206, Life Technologies, 1:100 in PBS/1% BSA) (82,83). Costaining for macrophage markers was then undertaken as described above. ...
The salivary glands often become damaged in individuals receiving radiotherapy for head and neck cancer, resulting in xerostomia, or chronic dry mouth. This leads to detrimental effects on their health and quality of life, for which there is no regenerative therapy. Macrophages are the predominant cell type in the salivary glands and are attractive therapeutic targets due to their unrivalled capacity to drive tissue repair and regeneration. Yet, the nature and role of macrophages in salivary gland homeostasis and whether or not they contribute to tissue repair/regeneration following injury is not well understood. Here, we have used single cell RNA-seq, multi-parameter flow cytometry and fluorescence microscopy to map the heterogeneity of the salivary gland macrophage compartment throughout development and following radiation-induced injury. We show that there are highly dynamic changes in the composition of the salivary gland macrophage compartment with age, in part due to changes in the ontogeny of these cells, determined using a suite of complementary fate mapping systems. A combination of mutant mice and antibody blockade demonstrates that salivary gland macrophages are dependent on CSF1, but not IL-34 or GM-CSF, for their development and maintenance. Finally, using an in vivo model of radiation-induced salivary gland injury combined with a novel Mafb-specific depletion system, we demonstrate an essential role for macrophages. Without macrophages the clearance of cells with DNA damage, and effective tissue repair following such injury, is severely comprised. Our data, therefore, indicate a strong case for exploring the therapeutic potential of manipulating macrophages in order to promote tissue repair and thus minimise salivary gland dysfunction after radiotherapy.
... Further functional studies are needed to support these observations, but in line with the work of several groups demonstrating the tissueresident characteristics of ILCs 8 and the existence of ILC niches in several tissues 13,36,37 , the histological approach used here also points towards the existence of microenvironments distinct in immune and stromal cell composition. ILCs in lymph nodes and spleen have been localized in the interfaces between T cell and B cell regions, but not deep within B cell follicles or T cell zones, and, there, they might interact with both B and T cells thereby shaping adaptive immunity [37][38][39][40] . Similarly, we find ILCs in human tonsils to localize around B cell follicles, but not within, in close contact to the fibronectin ring that lines and shapes such structures. ...
Innate lymphoid cells (ILCs) emerge in the last few years as important regulators of immune responses and biological processes. Although ILCs are mainly known as tissue-resident cells, their precise localization and interactions with the microenvironment are still unclear. Here we combine a multiplexed immunofluorescence technique and a customized computational, open-source analysis pipeline to unambiguously identify CD127⁺ ILCs in situ and characterize these cells and their microenvironments. Moreover, we reveal the transcription factor IRF4 as a marker for tonsillar ILC3, and identify conserved stromal landmarks characteristic for ILC localization. We also show that CD127⁺ ILCs share tissue niches with plasma cells in the tonsil. Our works thus provide a platform for multiparametric histological analysis of ILCs to improve our understanding of ILC biology.
... In contrast, membrane-bound lymphotoxin b (mLTab2) expressed on ILC3s induces iNOS + DCs, which are a prerequisite for IgA production, resulting in T-cell-independent IgA production by B cells. In human and mouse lymph nodes, ILC3s are present at the marginal sinus and interfollicular spaces near the marginal zone [14,185,186]. In humans, ILC3s provide the B-cell activation factor (BAFF), CD40L, and Notch ligand Delta-like 1 (DLL1) for marginal-zone B cells to produce innate IgM [186]. ...
The concept of innate lymphoid cells (ILCs) includes both conventional natural killer (NK) cells and helper ILCs, which resemble CD8+ killer T cells and CD4+ helper T cells in acquired immunity, respectively. Conventional NK cells are migratory cytotoxic cells that find tumor cells or cells infected with microbes. Helper ILCs are localized at peripheral tissue and are responsible for innate helper-cytokine production. Helper ILCs are classified into three subpopulations: TH1-like ILC1s, TH2-like ILC2s, and TH17/TH22-like ILC3s. Because of the functional similarities between ILCs and T cells, ILCs can serve as an innate component that augments each corresponding type of acquired immunity. However, the physiological functions of ILCs are more plastic and complicated than expected and are affected by environmental cues and types of inflammation. Here, we review recent advances in understanding the interaction between ILCs and acquired immunity, including T- and B-cell responses at various conditions. Immune suppressive activities by ILCs in particular are discussed in comparison to their immune stimulatory effects to gain precise knowledge of ILC biology and the physiological relevance of ILCs in human diseases.
... Antibodies raised against the following mouse antigens were used: CD3 (1:50; clone eBio500A2; eBioscience), IL-7Rα (1:25; clone A7R34; eBioscience), and RORγt (1:30; clone AFKJS-9; eBioscience). Detection of RORγt was achieved through amplification of the primary signal as described previously (Kim et al., 2011). Briefly, purified rat primary antibodies against RORγt were detected with donkey anti-rat-IgG-FITC (1:150; Jackson ImmunoResearch), and subsequently rabbit anti-FITC-AF488 (1:200; Life Technologies) and donkey anti-rabbit-IgG-AF488 (1:200; Life Technologies). ...
Intestinal immune homeostasis is dependent upon tightly regulated and dynamic host interactions with the commensal microbiota. Immunoglobulin A (IgA) produced by mucosal B cells dictates the composition of commensal bacteria residing within the intestine. While emerging evidence suggests the majority of IgA is produced innately and may be polyreactive, mucosal-dwelling species can also elicit IgA via T cell–dependent mechanisms. However, the mechanisms that modulate the magnitude and quality of T cell–dependent IgA responses remain incompletely understood. Here we demonstrate that group 3 innate lymphoid cells (ILC3) regulate steady state interactions between T follicular helper cells (TfH) and B cells to limit mucosal IgA responses. ILC3 used conserved migratory cues to establish residence within the interfollicular regions of the intestinal draining lymph nodes, where they act to limit TfH responses and B cell class switching through antigen presentation. The absence of ILC3-intrinsic antigen presentation resulted in increased and selective IgA coating of bacteria residing within the colonic mucosa. Together these findings implicate lymph node resident, antigen-presenting ILC3 as a critical regulatory checkpoint in the generation of T cell–dependent colonic IgA and suggest ILC3 act to maintain tissue homeostasis and mutualism with the mucosal-dwelling commensal microbiota.
... [10][11][12] Moreover, in humans, OX40L + ILC3s have been found in the tonsil. 13,14 In mice, the expression of OX40L on splenic Lti cells can be barely detected in neonates, whereas it increases after birth. 15 The mechanism underlying this time-dependent expression is unclear. ...
OX40L is one of the co-stimulatory molecules that can be expressed by splenic lymphoid tissue inducer (Lti) cells, a subset of group 3 innate lymphoid cells (ILC3s). OX40L expression in subsets of intestinal ILC3s and the molecular regulation of OX40L expression in ILC3s are unknown. Here, we showed intestinal ILC3s marked as an OX40Lhigh population among all the intestinal leukocytes and were the dominant source of OX40L in Rag1–/– mice. All ILC3 subsets expressed OX40L, and NCR–ILC3s were the most abundant source of OX40L. The expression of OX40L in ILC3s could be upregulated during inflammation. In addition to tumor necrosis factor (TNF)-like cytokine 1A (TL1A), which has been known as a trigger for OX40L, we found that Poly (I:C) representing viral stimulus promoted OX40L expression in ILC3s via a cell-autonomous manner. Furthermore, we demonstrated that IL-7-STAT5 signaling sustained OX40L expression by ILC3s. Intestinal regulatory T cells (Tregs), most of which expressed OX40, had defective expansion in chimeric mice, in which ILC3s were specifically deficient for OX40L expression. Consistently, co-localization of Tregs and ILC3s was found in the cryptopatches of the intestine, which suggests the close interaction between ILC3s and Tregs. Our study has unveiled the crosstalk between Tregs and ILC3s in mucosal tissues through OX40–OX40L signaling, which is crucial for the homeostasis of intestinal Tregs.
... Whether endothelial cells express the IL-22 receptor complex remains to be determined. IL-22 is produced by several types of cells of the lymphoid lineage and include activated T-cells as well as innate lymphoid cells such as natural killer cells, lymphoid tissue inducer cells, and lymphoid tissue inducer-like cells (43)(44)(45)(46)(47)(48)(49)(50). Which cell types are responsible for IL-22 secretion and the protective potential of this cytokine during rickettsial infections remains to be elucidated. ...
Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus , is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluores-cence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.
... p=.000, respectively). In line with our result, kim et al. found a significant association between serum IL-22 and ACCP antibodies 37 . Of potential implication, the strong association of elevated serum IL-22 with the more specific serologic marker, ACCP antibodies. ...
Objective: Interleukin (IL) -22 is a novel mediator of a member of IL-10 family cytokines that is produced by many different types of lymphocytes including both those of innate and adaptive immune system. This cytokine has potent proliferative and inflammatory effects on different cell lines. Recently, accumulated data has indicated that IL-22 plays an important role in the pathogenesis of rheumatoid arthritis (RA). We aimed to investigate the levels of IL-22 and its association with demographic, clinical data as well as serological markers in RA. Methods: IL-22 serum levels were measured in 45 newly diagnosed RA patients without any treatment and 45 healthy individuals as control by a manual Enzyme linked immunosorbent assay (ELISA). Correlations of IL-22 serum levels were sought with demographic, clinical data and serological parameters. IL-22 levels were significantly elevated in serum of RA patients (median= 86.89ng/ml and range = 896) compared to serum of healthy control (median=75.36ng/ml and range=459), p=.022. Results: The IL-22 levels were correlated positively with C-reactive protein (CRP), anti-cyclic citrullinated peptide (ACCP) antibodies in RA patients. Significant higher levels of serum IL-22 in RA patients compare with those in healthy control. Conclusion: Highly significant association between serum levels of IL-22 and the serological markers (CRP and ACCP antibodies) in the diagnosis of RA suggest the potential levels of IL-22 as a valuable biomarker for the evaluation of disease severity in RA patients. Peer Review History: Received 1 March 2018; Revised 1 April; Accepted 6 May, Available online 15 May 2018 Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.5/10 Average Peer review marks at publication stage: 8.0/10 Reviewer(s) detail: Dr. Hatem Sameir Abbas, Al-Azhar University, Egypt, hsam8406@yahoo.com Dr. George Zhu, Tehran University of Medical Sciences, Tehran, Iran, sansan4240732@163.com Similar Articles: THE ASSOCIATION BETWEEN LEVELS OF HEPCIDIN, IRON STATUS AND MICRO-INFLAMMATION MARKERS AMONG HAEMODIALYSIS
... Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified cytokine-cytokine receptor interactions and tumor necrosis factor (TNF) signaling pathways as significantly enriched in this gene set ( Figures 3B and 3C). In mouse and human SLOs, ILC3s localize to the T-B interface (Hoorweg et al., 2015;Kim et al., 2011). In line with this spatial positioning, lymph node and spleen ILC3s expressed both CXCR5 and CCR7 ( Figure 3D). ...
A substantial number of human and mouse group 3 innate lymphoid cells (ILC3s) reside in secondary lymphoid organs, yet the phenotype and function of these ILC3s is incompletely understood. Here, we employed an unbiased cross-tissue transcriptomic approach to compare human ILC3s from non-inflamed lymph nodes and spleen to their phenotypic counterparts in inflamed tonsils and from circulation. These analyses revealed that, in the absence of inflammation, lymphoid organ-residing ILC3s lack transcription of cytokines associated with classical ILC3 functions. This was independent of expression of the natural cytotoxicity receptor NKp44. However, and in contrast to ILC3s from peripheral blood, lymphoid organ-residing ILC3s express activating cytokine receptors and have acquired the ability to be recruited into immune responses by inflammatory cytokines. This comprehensive cross-tissue dataset will allow for identification of functional changes in human lymphoid organ ILC3s associated with human disease.
... October 2017 | Volume 8 | Article 1298 lymph nodes (62). Phenotypically, adult LTi-like CCR6 + ILC3 are very similar to the embryonic LTi population but additionally express molecules such as OX40L and CD30L that may foster interactions with lymphocytes (125)(126)(127)(128). Interestingly, expression of OX40L can be induced in embryonic LTi cells through ex vivo culture with inflammatory cytokines, such as TL1A (129). ...
The maintenance of mammalian health requires the generation of appropriate immune responses against a broad range of environmental and microbial challenges, which are continually encountered at barrier tissue sites including the skin, lung, and gastrointestinal tract. Dysregulated barrier immune responses result in inflammation, both locally and systemically in peripheral organs. Group 3 innate lymphoid cells (ILC3) are constitutively present at barrier sites and appear to be highly specialized in their ability to sense a range of environmental and host-derived signals. Under homeostatic conditions, ILC3 respond to local cues to maintain tissue homeostasis and restrict inflammatory responses. In contrast, perturbations in the tissue microenvironment resulting from disease, infection, or tissue damage can drive dysregulated pro-inflammatory ILC3 responses and contribute to immunopathology. The tone of the ILC3 response is dictated by a balance of “exogenous” signals, such as dietary metabolites and commensal microbes, and “endogenous” host-derived signals from stromal cells, immune cells, and the nervous system. ILC3 must therefore have the capacity to simultaneously integrate a wide array of complex and dynamic inputs in order to regulate barrier function and tissue health. In this review, we discuss the concept of ILC3 as a “communications hub” in the intestinal tract and associated lymphoid tissues and address the variety of signals, derived from multiple biological systems, which are interpreted by ILC3 to modulate the release of downstream effector molecules and regulate cell–cell crosstalk. Successful integration of environmental cues by ILC3 and downstream propagation to the broader immune system is required to maintain a tolerogenic and anti-inflammatory tone and reinforce barrier function, whereas dysregulation of ILC3 responses can contribute to the onset or progression of clinically relevant chronic inflammatory diseases.
... Moreover, the ILC panel stains significantly less clearly after the permeabilization that is required for cytokine or transcription factor staining. However, even without these confirmatory studies, we can identify subpopulations from their surface markers with a reasonable degree of confidence based on individual studies 8,12,15,17,22,32 and aggregate phenotyping data assembled in recent expert reviews. 11,21 Of note, we did not include ILC2-specific surface stains in our panel since these cells are thought to reside in the airway, skin, fat-associated lymphoid clusters, and mesenteric lymph nodes but not in significant numbers in the intestinal lumen. ...
Background:
Little is known about innate lymphoid cell (ILC) populations in the human gut, and the turnover of these cells and their subsets after transplantation has not been described.
Methods:
Intestinal samples were taken from 4 isolated intestine (ITx) and 3 multivisceral (MvTx) transplant recipients at the time of any operative resection, such as stoma closure or revision. ILCs were isolated and analyzed by flow cytometry. The target population was defined as being negative for lineage markers and double-positive for CD45/CD127. Cells were further stained to define ILC subsets and a donor- or recipient-specific HLA marker to analyze chimerism.
Results:
Donor-derived ILCs were found to persist greater than 8 years after transplantation. Additionally, the percentage of cells thought to be Lymphoid tissue inducer (LTi) cells among donor ILCs was far higher than that among recipient ILCs.
Conclusions:
Our findings demonstrate that donor-derived ILCs persist long-term after transplantation and support the notion that human LTi cells may form in the fetus and persist throughout life, as hypothesized in rodents. Correlation between chimerism and rejection, graft failure, and patient survival requires further study.
... IL-17 was initially found to be secreted by a subset of CD4 + T cells termed Th17 cells, which also secrete the cytokines IL-22 and IL-21 (Harrington et al. 2005;Langrish et al. 2005;Park et al. 2005;Korn et al. 2007;Zheng et al. 2007). However, recent studies identified several other cell types that contribute to IL-17 and IL-22 production (Wolk et al. 2002(Wolk et al. , 2011Kondo et al. 2009;Ortega et al. 2009), including activated CD4 + T cells (Harrington et al. 2005;Park et al. 2005;Wolk et al. 2011), CD8 + T cells (Kondo et al. 2009;Ortega et al. 2009), as well as various innate lymphoid cells (ILCs) such as natural killer (NK) cells (Hughes et al. 2010;Pandya et al. 2011), NKT cells (Rachitskaya et al. 2008), lymphoid tissue inducer (LTi) cells (Cupedo et al. 2009;Crellin et al. 2010) and LTilike cells (Luci et al. 2009;Kim et al. 2011) (Table 1). The role of these cells in secreting IL-17 and IL-22 is discussed in detail below. ...
Cytokines IL-17 and IL-22 play pivotal roles in host defense against microbes and in the development of chronic inflammatory diseases. These cytokines are produced by cells that are often located in epithelial barriers, including subsets of T cells and innate lymphoid cells. In general, IL-17 and IL-22 can be characterized as important cytokines in the rapid response to infectious agents, both by recruiting neutrophils and by inducing the production of antimicrobial peptides. Although each cytokine induces an innate immune response in epithelial cells, their functional spectra are generally distinct: IL-17 mainly induces an inflammatory tissue response and is involved in the pathogenesis of several autoimmune diseases, whereas IL-22 is largely protective and regenerative. In this review, we compare IL-17 and IL-22, describing overlaps and differences in their cellular sources as well as their regulation, signaling, biological functions, and roles during disease, with a focus on the contribution of these cytokines to the gut mucosal barrier during bacterial infection.
... However, we also observed expression of NK lineage markers such as CD122, CD161 and CD7 on ILCs. In order to better assess what proportion of ILCs represent true LTi cells, as compared to ILC22 cells, we stained ILCs and NK cells for NKp44 (marker of ILC22), CD25 (expressed on LTi cells) and two TNF-super family receptor ligands, which have been previously shown to be expressed on virtually all (OX40L; (37)) or a proportion (CD30L; (35)) of human LTi cells (Fig. 1E13.4% of blood ILCs (range 0.0–31.0%) and 11.0% of CD56 bright NK cells (range 0.1– 23.2%). ...
... Although ILC3s largely lack canonical co-stimulatory molecules such as CD80 and CD86 (25,26), they express several other molecules that enable modulation of adaptive immune responses, including CD30L and OX40L (104,105). Mice lacking both CD30L and OX40L are unable to sustain germinal center formation and antibody production and ILC3s expressing these molecules were found to cluster in the interfollicular zone and form interactions with memory T cells following bacterial infection (106)(107)(108), suggesting that ILC3s may prevent inflammatory responses while also supporting memory cell responses necessary for optimal immunity. Taken together, these studies support a role for ILC3s in supporting B-cell class switching and antibody production and suggest that ILC3 modulation of CD4 + T-cell responses may be dependent upon the quality of the T-cell response, the local inflammatory milieu and the context of antigen delivery. ...
A delicate balance exists between the mammalian immune system and normally beneficial commensal bacteria that colonize the
gastrointestinal tract, which is necessary to maintain tissue homeostasis. Dysregulation of these interactions between the
host and commensal bacteria is causally associated with chronic inflammation and the development of cancer. In contrast, recent
reports have highlighted that commensal bacteria also play an essential role in promoting anti-tumor immune responses in several
contexts, highlighting a paradox whereby interactions between the host and commensal bacteria can influence both pro- and
anti-tumor immunity. Given the critical roles for group 3 innate lymphoid cells (ILC3s) in regulating inflammation, tissue
repair and host–microbe interactions in the intestine, here we discuss new evidence that ILC3s may profoundly influence the
development, progression and control of tumors. In this review, we provide an overview of recent advances in understanding
the impact of commensal bacteria on tumorigenesis, discuss recent findings identifying ILC3s as critical regulators of host–microbe
interactions and highlight the emerging role of this immune cell population in cancer and their potential implication as a
therapeutic target.
... Finally, we assessed whether the fetal colocalization of RANKL + stromal cells and Rorgt + ILC3 was maintained into adulthood. Fig. 4D shows that Rorgt + ILC3 reside mainly in the interfollicular areas of adult human LNs (38), in close proximity to RANKL + MRC. These data establish that the phenotype and localization of human MRC are phenotypically similar to human fetal LTo cells and correspond to that of murine MRC. ...
Adaptive immunity critically depends on the functional compartmentalization of secondary lymphoid organs. Mesenchymal stromal cells create and maintain specialized niches that support survival, activation, and expansion of T and B cells, and integrated analysis of lymphocytes and their niche has been instrumental in understanding adaptive immunity. Lymphoid organs are also home to type 3 innate lymphoid cells (ILC3), innate effector cells essential for barrier immunity. However, a specialized stromal niche for ILC3 has not been identified. A novel lineage-tracing approach now identifies a subset of murine fetal lymphoid tissue organizer cells that gives rise exclusively to adult marginal reticular cells. Moreover, both cell types are conserved from mice to humans and colocalize with ILC3 in secondary lymphoid tissues throughout life. In sum, we provide evidence that fetal stromal organizers give rise to adult marginal reticular cells and form a dedicated stromal niche for innate ILC3 in adaptive lymphoid organs.
... A T-box transcription factor, T-bet, also plays a role in the generation of IL-22-producing ILCs as Tbx21 deficiency leads to elimination of these cells in the intestinal lamina propria and impairs IL-22 production [12]. In humans, LTi cells are characterized by their expression of CD117 and CD127 [13,14] and are critically involved in the development of secondary lymphoid tissues including lymph nodes, Peyer's patches and cryptopatches [15]. ...
... During fetal and neonatal life, LTi cells induce the formation of secondary lymphoid tissue through expression of the TNF-related cytokine, lymphotoxin (LT)ab, which differentiates stromal and myeloid cells into organized microenvironments for host defense (1,4,5) and promotes thymic T cell selection (6). In the adult, LTi cells provide survival signals to innate (7) and adaptive lymphocytes (8)(9)(10) via expression of the TNF family members OX40 ligand and CD30 ligand. Fate-mapping experiments indicate that LTi cells may be the progenitors to the subset of innate lymphoid cells (ILCs) (11) that primarily produce IL-22 (group 3 ILCs) to maintain normal gut physiology (12)(13)(14) and protect from intestinal infection (15). ...
Innate lymphoid cells encompass a diverse array of lymphocyte subsets with unique phenotype that initiate inflammation and provide host defenses in specific microenvironments. In this study, we identify a rare human CD4(+)CD3(-) innate-like lymphoid population with high TNF expression that is enriched in blood from patients with rheumatoid arthritis. These CD4(+)CD3(-) cells belong to the T cell lineage, but the lack of AgR at the cell surface renders them nonresponsive to TCR-directed stimuli. By developing a culture system that sustains survival, we show that CD4(+)CD3(-) innate-like T cells display IL-7-dependent induction of surface lymphotoxin-αβ, demonstrating their potential to modify tissue microenvironments. Furthermore, expression of CCR6 on the CD4(+)CD3(-) population defines a CD127(high) subset that is highly responsive to IL-7. This CD4(+)CD3(-) population is enriched in the peripheral blood from rheumatoid arthritis patients, suggesting a link to their involvement in chronic inflammatory disease.
... For instance, the lymphotoxin beta receptor (LTβR) ligands on LTi that program lymph node development (Futterer et al., 1998) are exclusive to placental mammals, but the RANKL expressed by LTi as part of lymph node development also occurs in teleost genomes (Kong et al., 1999). Additionally, our work has shown that adult LTi are distinguished from the neonatal population by their expression of high levels of OX40 ligand (OX40L, TNFSF4; Kim et al., 2011) and in mouse CD30L (TNFSF8; Kim et al., 2003). Our studies have found that CD4 T cell memory function is highly dependent on signaling through both OX40 and CD30 suggesting additional roles for LTi in the mediation of adaptive CD4-dependent immune responses. ...
Phylogeny suggests that the evolution of placentation in mammals was accompanied by substantial changes in the mammalian immune system: in particular lymph nodes and CD4 high affinity memory antibody responses co-evolved during the same period. Lymphoid tissue inducer cells (LTi) are members of an emerging family of innate lymphoid cells (ILCs) that are crucial for lymph node development, but our studies have indicated that they also play a pivotal role in the long-term maintenance of memory CD4 T cells in adult mammals through their expression of the tumor necrosis family members, OX40- and CD30-ligands. Additionally, our studies have shown that these two molecules are also key operators in CD4 effector function, as their absence obviates the need for the FoxP3 dependent regulatory T (Tregs) cells that prevent CD4 driven autoimmune responses. In this perspective article, we summarize findings from our group over the last 10 years, and focus specifically on the role of LTi in thymus. We suggest that like memory CD4 T cells, LTi also play a role in the selection and maintenance of the Tregs that under normal circumstances are absolutely required to regulate CD4 effector cells.
The salivary glands often become damaged in individuals receiving radiotherapy for head and neck cancer, resulting in chronic dry mouth. This leads to detrimental effects on their health and quality of life, for which there is no regenerative therapy. Macrophages are the predominant immune cell in the salivary glands and are attractive therapeutic targets due to their unrivaled capacity to drive tissue repair. Yet, the nature and role of macrophages in salivary gland homeostasis and how they may contribute to tissue repair after injury are not well understood. Here, we show that at least two phenotypically and transcriptionally distinct CX3CR1 ⁺ macrophage populations are present in the adult salivary gland, which occupy anatomically distinct niches. CD11c ⁺ CD206 – CD163 – macrophages typically associate with gland epithelium, whereas CD11c ⁻ CD206 ⁺ CD163 ⁺ macrophages associate with blood vessels and nerves. Using a suite of complementary fate mapping systems, we show that there are highly dynamic changes in the ontogeny and composition of salivary gland macrophages with age. Using an in vivo model of radiation-induced salivary gland injury combined with genetic or antibody-mediated depletion of macrophages, we demonstrate an essential role for macrophages in clearance of cells with DNA damage. Furthermore, we show that epithelial-associated macrophages are indispensable for effective tissue repair and gland function after radiation-induced injury, with their depletion resulting in reduced saliva production. Our data, therefore, provide a strong case for exploring the therapeutic potential of manipulating macrophages to promote tissue repair and thus minimize salivary gland dysfunction after radiotherapy.
Microbial colonization of the mammalian intestine elicits inflammatory or tolerogenic T cell responses, but the mechanisms controlling these distinct outcomes remain poorly understood, and accumulating evidence indicates that aberrant immunity to intestinal microbiota is causally associated with infectious, inflammatory and malignant diseases1–8. Here we define a critical pathway controlling the fate of inflammatory versus tolerogenic T cells that respond to the microbiota and express the transcription factor RORγt. We profiled all RORγt+ immune cells at single-cell resolution from the intestine-draining lymph nodes of mice and reveal a dominant presence of T regulatory (Treg) cells and lymphoid tissue inducer-like group 3 innate lymphoid cells (ILC3s), which co-localize at interfollicular regions. These ILC3s are distinct from extrathymic AIRE-expressing cells, abundantly express major histocompatibility complex class II, and are necessary and sufficient to promote microbiota-specific RORγt+ Treg cells and prevent their expansion as inflammatory T helper 17 cells. This occurs through ILC3-mediated antigen presentation, αV integrin and competition for interleukin-2. Finally, single-cell analyses suggest that interactions between ILC3s and RORγt+ Treg cells are impaired in inflammatory bowel disease. Our results define a paradigm whereby ILC3s select for antigen-specific RORγt+ Treg cells, and against T helper 17 cells, to establish immune tolerance to the microbiota and intestinal health. ILC3s expressing MHC class II control the fate of inflammatory versus tolerogenic T cells that respond to the microbiota by selecting for antigen-specific RORγt+ Treg cells and against TH17 cells, establishing intestinal homoeostasis.
Natural killer (NK) cells have long been recognized for their anti-cancer activity and are now included in the large family of innate lymphoid cells (ILCs). The discovery of new ILC subsets that, similarly to NK cells, are able to kill tumor cells encourages us to redefine NK cell role in anti-tumor immunity. Conventional NK cells circulate through the blood and screen the body for “stressed” cells. Therefore, NK cells are believed to play a key role in cancer immunosurveillance by the early elimination of cells undergoing malignant transformation. Tissue-resident ILCs might play a similar role since they are ideally located to detect the early signs of malignant transformation in their organ of residence. We are only beginning to appreciate the importance of the whole ILC family in cancer. Confusingly, these cells have been reported to both inhibit and fuel cancer progression and the factors regulating these dual functions remain unclear. Here, I review the recent advances in our understanding of cytotoxic and cytokine-producing helper ILC subsets in cancer.
In recent years monoclonal antibodies (mAbs) able to reinvigorate anti-tumor T cell immunity have heralded a paradigm shift in cancer treatment. The most high profile of these mAbs block the inhibitory checkpoint receptors PD-1 and CTLA-4 and have improved life expectancy for patients across a range of tumor types. However, it is becoming increasingly clear that failure of some patients to respond to checkpoint inhibition is due to inadequate T-cell priming. For full T-cell activation two signals must be received and ligands providing the second of these signals, termed costimulation, are often lacking in tumors. Members of the TNF receptor superfamily (TNFRSF) are key co-stimulators of T cells during infection and there has been an increasing interest in harnessing these receptors to augment tumor immunity. We here review the immunobiology of two particularly promising TNFRSF target receptors, CD27 and OX40, and their respective ligands CD70 and OX40L, focusing on their role within a tumor setting. We describe the influence of CD27 and OX40 on human T cells based on in vitro studies and on the phenotypes of several recently described individuals exhibiting natural deficiencies in CD27/CD70 and OX40. Finally we review key literature describing progress in elucidating the efficacy and mode of action of OX40- and CD27-targeting mAbs in pre-clinical models and provide an overview of current clinical trials targeting these promising receptor/ligand pairings in cancer.
Cancer cells tend to metastasize first to tumor-draining lymph nodes (LN), but the mechanisms mediating cancer cell invasion into the lymphatic vasculature remain little understood. Here we show that in the human breast tumor microenvironment (TME) the presence of increased numbers of RORγt+ group 3 innate lymphoid cells (ILC3) correlates with an increased likelihood of LN metastasis. In a preclinical mouse model of breast cancer, CCL21-mediated recruitment of ILC3 to tumors stimulated the production of the CXCL13 by TME stromal cells, which in turn promoted ILC3-stromal interactions and production of the cancer cell motile factor RANKL. Depleting ILC3 or neutralizing CCL21, CXCL13 or RANKL was sufficient to decrease LN metastasis. Our findings establish a role for RORγt+ILC3 in promoting lymphatic metastasis by modulating the local chemokine milieu of cancer cells in the TME.
Innate lymphoid cells (ILCs) were identified principally as non-T cell sources of key cytokines, able to provide rapid and early production of these molecules in the support of tissue homeostasis, repair and response to infection. As our understanding of these cells has developed, it has become evident that ILCs can impact on lymphocytes through a range of mechanisms. Thus an exciting area of research has evolved in determining the extent to which ILCs may regulate adaptive immune responses. This review will focus initially on our current understanding of where ILC populations are located and what this means for potential cellular interactions. Mechanisms underpinning such interactions and how this may contribute to controlling adaptive immunity will then be considered. This article is protected by copyright. All rights reserved.
Many studies from recent years have shown that cytokines like IL-22, IL-17A, and IL-17F play a major role in both the defense against certain microbes and the development and maintenance of chronic inflammatory diseases. These mediators are often secreted by subpopulations of T-helper cells called Th17 cells and Th22 cells, respectively. This chapter provides an overview about the common and differing properties of IL-22, IL-17A, and IL-17F with respect to their genes, protein structure, cellular sources, receptors, target cells, and biological effects. Surprisingly, with the exception of a few similarities, most basic aspects of IL-22 and IL-17A/IL-17F are different.
Innate lymphoid cells (ILCs) are identified as novel population of hematopoietic cells which protect the body by coordinating the innate immune response against a wide range of threats including infections, tissue damages and homeostatic disturbances. ILCs, particularly ILC2 cells, are found throughout the body including the brain. ILCs are morphologically similar to lymphocytes, express and release high levels of T-helper (Th)1, Th2 and Th17 cytokines but do not express classical cell-surface markers that are associated with other immune cell lineages.
Three types of ILCs (ILC1, 2 & 3) have been reported depending upon the cytokines produced. ILC1 cells encompass natural killer (NK) cells and interferon (IFN)- releasing cells; ILC2 cells release the Th2 cytokines, IL-5, IL-9 and IL-13 in response to IL-25 and IL-33; and ILC3 cells which release IL-17 and IL-22. ILC2 cells have been implicated in mucosal reactions occurring in animal models of allergic asthma and virus-induced lung disorders resulting in the regulation of airway remodeling and tissue homeostasis.
There is evidence for increased ILC2 cell numbers in allergic responses in man but little is known about the role of ILCs in chronic obstructive pulmonary disease (COPD). Further understanding of the characteristics of ILCs such as their origin, location and phenotypes and function would help to clarify the role of these cells in the pathogenesis of various lung diseases.
In this review we will focus on the role of ILC2 cells and consider their origin, function, location and possible role in the pathogenesis of the chronic inflammatory disorders such as asthma and COPD.
Innate lymphoid cells (ILCs) are identified as novel population of hematopoietic cells which protect the body by coordinating the innate immune response against a wide range of threats including infections, tissue damages and homeostatic disturbances. ILCs, particularly ILC2 cells, are found throughout the body including the brain. ILCs are morphologically similar to lymphocytes, express and release high levels of T-helper (Th)1, Th2 and Th17 cytokines but do not express classical cell-surface markers that are associated with other immune cell lineages.
Three types of ILCs (ILC1, 2 & 3) have been reported depending upon the cytokines produced. ILC1 cells encompass natural killer (NK) cells and interferon (IFN)- releasing cells; ILC2 cells release the Th2 cytokines, IL-5, IL-9 and IL-13 in response to IL-25 and IL-33; and ILC3 cells which release IL-17 and IL-22. ILC2 cells have been implicated in mucosal reactions occurring in animal models of allergic asthma and virus-induced lung disorders resulting in the regulation of airway remodeling and tissue homeostasis.
There is evidence for increased ILC2 cell numbers in allergic responses in man but little is known about the role of ILCs in chronic obstructive pulmonary disease (COPD). Further understanding of the characteristics of ILCs such as their origin, location and phenotypes and function would help to clarify the role of these cells in the pathogenesis of various lung diseases.
In this review we will focus on the role of ILC2 cells and consider their origin, function, location and possible role in the pathogenesis of the chronic inflammatory disorders such as asthma and COPD.
The current study explored the relationship between lymphoid tissue inducer (LTi) cells and patients' clinical and immunological status. LTi cells are critical for lymphoid tissue development and maintenance of CD4 T cell-dependent immune responses. The percentage of CD117(+)CD3(-)CD56(-)CD127(+) RORγ(+) LTi cells isolated from human tonsils was determined and correlated with changes in other immune subsets and clinical factors. We found that the portion of LTi and CD4 T cells was significantly increased in chronic tonsillitis compared to non-inflamed tonsils. Additionally, the expression of OX40 by memory CD4 T cells and OX40 ligand (OX40L) and interleukin (IL)-22 by LTi cells was higher in chronically inflamed tonsils. The treatment for tonsillitis with ibuprofen did not alter LTi cell viability and the expression of OX40L and IL-22. These results demonstrate that during chronic inflammation, LTi cells are increased and express higher levels of OX40L and IL-22, and this is correlated with an increase in memory CD4 T cells.
The family of innate lymphoid cells (ILCs) comprises of natural killer (NK) cells, Rorγt-dependent ILCs (lymphoid tissue inducer (LTi) cells, ILC22, and ILC17), and type 2 ILCs. Apart from a common requirement for inhibitor of DNA binding 2 (Id2) expression and common γ-chain (γ) signaling, the differentiation of ILC populations is regulated by distinct transcription factors. ILCs play fundamental roles in processes such as cytotoxicity, lymphoid organogenesis, intestinal homeostasis, immunity against infections, and wound healing. However, the dysregulation of ILCs has been implicated in autoimmune and inflammatory diseases. Here, we will review the recent advances in ILC development and their roles in immunity and disease, with a primary focus on type 2 ILCs.
The evolution of immune blockades in tumors limits successful antitumor immunity, but the mechanisms underlying this process are not fully understood. Depletion of regulatory T cells (Treg), a T-cell subset that dampens excessive inflammatory and autoreactive responses, can allow activation of tumor-specific T cells. However, cancer immunotherapy studies have shown that a persistent failure of activated lymphocytes to infiltrate tumors remains a fundamental problem. In evaluating this issue, we found that despite an increase in T-cell activation and proliferation following Treg depletion, there was no significant association with tumor growth rate. In contrast, there was a highly significant association between low tumor growth rate and the extent of T-cell infiltration. Further analyses revealed a total concordance between low tumor growth rate, high T-cell infiltration, and the presence of high endothelial venules (HEV). HEV are blood vessels normally found in secondary lymphoid tissue where they are specialized for lymphocyte recruitment. Thus, our findings suggest that Treg depletion may promote HEV neogenesis, facilitating increased lymphocyte infiltration and destruction of the tumor tissue. These findings are important as they point to a hitherto unidentified role of Tregs, the manipulation of which may refine strategies for more effective cancer immunotherapy. Cancer Res; 72(21); 1-10. ©2012 AACR.
Phylogeny shows that CD4 T cell memory and lymph nodes coevolved in placental mammals. In ontogeny, retinoic acid orphan receptor (ROR)γ-dependent lymphoid tissue inducer (LTi) cells program the development of mammalian lymph nodes. In this study, we show that although primary CD4 T cell expansion is normal in RORγ-deficient mice, the persistence of memory CD4 T cells is RORγ-dependent. Furthermore, using bone marrow chimeric mice we demonstrate that LTi cells are the key RORγ-expressing cell type sufficient for memory CD4 T cell survival in the absence of persistent Ag. This effect was specific for CD4 T cells, as memory CD8 T cells survived equally well in the presence or absence of LTi cells. These data demonstrate a novel role for LTi cells, archetypal members of the innate lymphoid cell family, in supporting memory CD4 T cell survival in vivo.
Genetic polymorphisms in the interleukin-2 receptor α (IL-2Rα) chain (CD25) locus are associated with several human autoimmune diseases, including multiple sclerosis (MS). Blockade of CD25 by the humanized monoclonal antibody daclizumab decreases MS-associated inflammation but has surprisingly limited direct inhibitory effects on activated T cells. The present study describes unexpected effects of daclizumab therapy on innate lymphoid cells (ILCs). The number of circulating retinoic acid receptor-related orphan receptor γt-positive ILCs, which include lymphoid tissue inducer (LTi) cells, was found to be elevated in untreated MS patients compared to healthy subjects. Daclizumab therapy not only decreased numbers of ILCs but also modified their phenotype away from LTi cells and toward a natural killer (NK) cell lineage. Mechanistic studies indicated that daclizumab inhibited differentiation of LTi cells from CD34⁺ hematopoietic progenitor cells or c-kit⁺ ILCs indirectly, steering their differentiation toward immunoregulatory CD56(bright) NK cells through enhanced intermediate-affinity IL-2 signaling. Because adult LTi cells may retain lymphoid tissue-inducing capacity or stimulate adaptive immune responses, we indirectly measured intrathecal inflammation in daclizumab-treated MS patients by quantifying the cerebrospinal fluid chemokine (C-X-C motif) ligand 13 and immunoglobulin G index. Both of these inflammatory biomarkers were inhibited by daclizumab treatment. Our study indicates that ILCs are involved in the regulation of adaptive immune responses, and their role in human autoimmunity should be investigated further, including their potential as therapeutic targets.
Interleukin-7 (IL-7) is known since many years as stromal-cell derived cytokine that plays a key role for the adaptive immune system. It promotes lymphocyte development in the bone marrow and thymus as well as naive and memory T cell homeostasis in the periphery. More recently, IL-7 reporter mice and other approaches have led to the further characterization of the various stromal cell sources of IL-7 in secondary lymphoid organs (SLO) and other tissues. We will review these advances along with a discussion of the regulation of IL-7 and its receptor, and compare the biological effects IL-7 has on adaptive as well as innate immune cells in SLO. Finally, we will review the role of IL-7 in development of SLO and tertiary lymphoid tissues that frequently are associated with sites of chronic inflammation.
Lymphoid tissue inducer cells (LTi) are a relatively new arrival on the immunological cellular landscape, having first been characterized properly only 15 years ago. They are members of an emerging family of innate lymphoid cells (ILCs). Elucidation of their function reveals links not only with the ancient innate immune system, but also with adaptive immune responses, in particular the development of lymph nodes and CD4(+) T cell memory immune responses, which on one hand underpin the success of vaccination strategies, and on the other hand drive many human immunologically mediated diseases. This perspective article is not an exhaustive account of the role of LTi in the development of lymphoid tissues, as there have been many excellent reviews published already. Instead, we combine current knowledge of genetic phylogeny and comparative immunology, together with classical mouse genetics, to suggest how LTi might have evolved from a primitive lymphocytic innate cell in the ancestral 500-million-year-old vertebrate immune system into a cell critical for adaptive CD4(+) T cell immune responses in mammals.
Innate lymphoid cells (ILCs) are immune cells that lack a specific antigen receptor yet can produce an array of effector cytokines that in variety match that of T helper cell subsets. ILCs function in lymphoid organogenesis, tissue remodeling, antimicrobial immunity, and inflammation, particularly at barrier surfaces. Their ability to promptly respond to insults inflicted by stress-causing microbes strongly suggests that ILCs are critical in first-line immunological defenses. Here, we review current data on developmental requirements, lineage relationships, and effector functions of two families of ILCs: (a) Rorγt-expressing cells involved in lymphoid tissue formation, mucosal immunity, and inflammation and (b) type 2 ILCs that are important for helminth immunity. We also discuss the potential roles of ILCs in the pathology of immune-mediated inflammatory and infectious diseases including allergy.
Patients with idiopathic pulmonary arterial hypertension (IPAH) present circulating autoantibodies against vascular wall components. Pathogenic antibodies may be generated in tertiary (ectopic) lymphoid tissues (tLTs).
To assess the frequency of tLTs in IPAH lungs, as compared with control subjects and flow-induced PAH in patients with Eisenmenger syndrome, and to identify local mechanisms responsible for their formation, perpetuation, and function.
tLT composition and structure were studied by multiple immunostainings. Cytokine/chemokine and growth factor expression was quantified by real-time polymerase chain reaction and localized by immunofluorescence. The systemic mark of pulmonary lymphoid neogenesis was investigated by flow cytometry analyses of circulating lymphocytes.
As opposed to lungs from control subjects and patients with Eisenmenger syndrome, IPAH lungs contained perivascular tLTs, comprising B- and T-cell areas with high endothelial venules and dendritic cells. Lymphocyte survival factors, such as IL-7 and platelet-derived growth factor-A, were expressed in tLTs as well as the lymphorganogenic cytokines/chemokines, lymphotoxin-α/-β, CCL19, CCL20, CCL21, and CXCL13, which might explain the depletion of circulating CCR6(+) and CXCR5(+) lymphocytes. tLTs were connected with remodeled vessels via an ER-TR7(+) stromal network and supplied by lymphatic channels. The presence of germinal center centroblasts, follicular dendritic cells, activation-induced cytidine deaminase, and IL-21(+)PD1(+) follicular helper T cells in tLTs together with CD138(+) plasma cell accumulation around remodeled vessels in areas of immunoglobulin deposition argued for local immunoglobulin class switching and ongoing production.
We highlight the main features of lymphoid neogenesis specifically in the lungs of patients with IPAH, providing new evidence of immunological mechanisms in this severe condition.
CD4(+) effector and memory T cells play a pivotal role in the development of both normal and pathogenic immune responses. This review focuses on the molecular and cellular mechanisms that regulate their development, with particular focus on the tumor necrosis factor superfamily members OX40 (TNFRSF4) and CD30 (TNFRSF8). We discuss the evidence that in mice, these molecular signaling pathways act synergistically to regulate the development of both effector and memory CD4(+) T cells but that the cells that regulate memory versus effector function are distinct, effectively allowing the independent regulation of the memory and effector CD4(+) T-cell pools.
The growing family of interleukin (IL)-12-like cytokines produced by activated macrophages and dendritic cells became the important players in the control of infections, development of inflammation, autoimmunity and cancer. However, the role of one of them-heterodimer IL-23, which consists of IL12p40 and the unique p19 subunit in HIV-1 infection pathogenesis and progression to AIDS, represent special interest. We overviewed findings of IL-23 involvement in control of peripheral bacterial pathogens and opportunistic infection, central nervous system (CNS) viral infections and autoimmune disorders, and tumorogenesis, which potentially could be applicable to HIV-1 and AIDS.
Lymphoid tissue–inducer (LTi) cells initiate the development of lymphoid tissues through the activation of local stromal cells
in a process similar to inflammation. LTi cells express the nuclear hormone receptor RORγt, which also directs the expression
of the proinflammatory cytokine interleukin-17 in T cells. We show here that LTi cells are part of a larger family of proinflammatory
RORγt+ innate lymphoid cells (ILCs) that differentiate from distinct fetal liver RORγt+ precursors. The fate of RORγt+ ILCs is determined by mouse age, and after birth, favors the generation of cells involved in intestinal homeostasis and defense.
Contrary to RORγt+ T cells, however, RORγt+ ILCs develop in the absence of microbiota. Our study indicates that RORγt+ ILCs evolve to preempt intestinal colonization by microbial symbionts.
Among human natural killer (NK) cell intermediates in secondary lymphoid tissue (SLT), stage 3 CD34(-)CD117(+)CD161(+)CD94(-) immature NK (iNK) cells uniquely express aryl hydrocarbon receptor (AHR) and interleukin-22 (IL-22), supporting a role in mucosal immunity. The mechanisms controlling proliferation and differentiation of these cells are unknown. Here we demonstrate that the IL-1 receptor IL-1R1 was selectively expressed by a subpopulation of iNK cells that localized proximal to IL-1beta-producing conventional dendritic cells (cDCs) within SLT. IL-1R1(hi) iNK cells required continuous exposure to IL-1beta to retain AHR and IL-22 expression, and they proliferate in direct response to cDC-derived IL-15 and IL-1beta. In the absence of IL-1beta, a substantially greater fraction of IL-1R1(hi) iNK cells differentiated to stage 4 NK cells and acquired the ability to kill and secrete IFN-gamma. Thus, cDC-derived IL-1beta preserves and expands IL-1R1(hi)IL-22(+)AHR(+) iNK cells, potentially influencing human mucosal innate immunity during infection.
Lymphoid tissue inducer (LTi) cells are required for lymph node formation during fetal development, and recent evidence implies a role in mucosal immunity in the adult. LTi cells share some phenotypic features of conventional natural killer (NK; cNK) cells; however, little is known to date about the relationship between these two cell types. We show that lineage(-) (Lin(-)) CD127(+)RORC(+) LTi-like cells in human tonsil are precursors to CD56(+)CD127(+)RORC(+)NKp46(+) cells, which together comprise a stable RORC(+) lineage. We find that LTi-like cells and their CD56(+) progeny can be expanded and cloned ex vivo without loss of function and without conversion into cNK cells. Clonal analysis reveals heterogeneity of cytokine production within the CD127(+) LTi-like population. Furthermore, we identify within the tonsil a cNK precursor population that is characterized as Lin(-)CD117(+)CD161(+)CD127(-) cells. Overall, we propose that CD127(+)RORC(+) cells, although they share some characteristics with cNK cells, represent a functionally and developmentally distinct lineage.
Although CD4(+) memory T cells reside within secondary lymphoid tissue, the major reservoir of these cells is in the lamina propria of the intestine. In this study, we demonstrate that, in the absence of signals through both OX40 and CD30, CD4(+) T cells are comprehensively depleted from the lamina propria. Deficiency in either CD30 or OX40 alone reduced CD4(+) T cell numbers, however, in mice deficient in both OX40 and CD30, CD4(+) T cell loss was greatly exacerbated. This loss of CD4(+) T cells was not due to a homing defect because CD30 x OX40-deficient OTII cells were not impaired in their ability to express CCR9 and alpha(4)beta(7) or traffic to the small intestine. There was also no difference in the priming of wild-type (WT) and CD30 x OX40-deficient OTII cells in the mesenteric lymph node after oral immunization. However, following oral immunization, CD30 x OX40-deficient OTII cells trafficked to the lamina propria but failed to persist compared with WT OTII cells. This was not due to reduced levels of Bcl-2 or Bcl-XL, because expression of these was comparable between WT and double knockout OTII cells. Collectively, these data demonstrate that signals through CD30 and OX40 are required for the survival of CD4(+) T cells within the small intestine lamina propria.
The interleukin (IL) 17 family of cytokines has emerged to be critical for host defense as well as the pathogenesis of autoimmune and autoinflammatory disorders, and serves to link adaptive and innate responses. Recent studies have identified a new subset of T cells that selectively produce IL-17 (Th17 cells; Bettelli, E., T. Korn, and V.K. Kuchroo. 2007. Curr. Opin. Immunol. 19:652-657; Kolls, J.K., and A. Linden. 2004. Immunity. 21:467-476), but the regulation of IL-17 production by innate immune cells is less well understood. We report that in vitro stimulation with IL-23 induced IL-17 production by recombination activating gene (Rag) 2(-/-) splenocytes but not Rag2(-/-) common gamma chain(-/-) splenocytes. We found that a major source of IL-17 was CD4(+)CD3(-)NK1.1(-)CD11b(-)Gr1(-)CD11c(-)B220(-) cells, a phenotype that corresponds to lymphoid tissue inducer-like cells (LTi-like cells), which constitutively expressed the IL-23 receptor, aryl hydrocarbon receptor, and CCR6. In vivo challenge with the yeast cell wall product zymosan rapidly induced IL-17 production in these cells. Genetic deletion of signal transducer and activator of transcription 3 reduced but did not abrogate IL-17 production in LTi-like cells. Thus, it appears that splenic LTi-like cells are a rapid source of IL-17 and IL-22, which might contribute to dynamic organization of secondary lymphoid organ structure or host defense.
NKp46+CD3- natural killer lymphocytes isolated from blood, lymphoid organs, lung, liver and uterus can produce granule-dependent cytotoxicity and interferon-gamma. Here we identify in dermis, gut lamina propria and cryptopatches distinct populations of NKp46+CD3- cells with a diminished capacity to degranulate and produce interferon-gamma. In the gut, expression of the transcription factor RORgammat, which is involved in the development of lymphoid tissue-inducer cells, defined a previously unknown subset of NKp46+CD3- lymphocytes. Unlike RORgammat- lamina propria and dermis natural killer cells, gut RORgammat+NKp46+ cells produced interleukin 22. Our data show that lymphoid tissue-inducer cells and natural killer cells shared unanticipated similarities and emphasize the heterogeneity of NKp46+CD3- cells in innate immunity, lymphoid organization and local tissue repair.
The mucosal immune system of the intestine is separated from a vast array of microbes by a single layer of epithelial cells. Cues from the commensal microflora are needed to maintain epithelial homeostasis, but the molecular and cellular identities of these cues are unclear. Here we provide evidence that signals from the commensal microflora contribute to the differentiation of a lymphocyte population coexpressing stimulatory natural killer cell receptors and the transcription factor RORgammat that produced interleukin 22 (IL-22). The emergence of these IL-22-producing RORgammathiNKp46+NK1.1(int) cells depended on RORgammat expression, which indicated that these cells may have been derived from lymphoid tissue-inducer cells. IL-22 released by these cells promoted the production of antimicrobial molecules important in the maintenance of mucosal homeostasis.
Natural killer (NK) cells are classically viewed as lymphocytes that provide innate surveillance against virally infected cells and tumour cells through the release of cytolytic mediators and interferon (IFN)-gamma. In humans, blood CD56(dim) NK cells specialize in the lysis of cell targets. In the lymph nodes, CD56(bright) NK cells secrete IFN-gamma cooperating with dendritic cells and T cells in the generation of adaptive responses. Here we report the characterization of a human NK cell subset located in mucosa-associated lymphoid tissues, such as tonsils and Peyer's patches, which is hard-wired to secrete interleukin (IL)-22, IL-26 and leukaemia inhibitory factor. These NK cells, which we refer to as NK-22 cells, are triggered by acute exposure to IL-23. In vitro, NK-22-secreted cytokines stimulate epithelial cells to secrete IL-10, proliferate and express a variety of mitogenic and anti-apoptotic molecules. NK-22 cells are also found in mouse mucosa-associated lymphoid tissues and appear in the small intestine lamina propria during bacterial infection, suggesting that NK-22 cells provide an innate source of IL-22 that may help constrain inflammation and protect mucosal sites.
Peyer's patch (PP) organogenesis proceeds through three histologically distinct steps: formation of organizing centers expressing VCAM-1 and ICAM-1 in segregated regions of the intestine at 15.5 days post-coitus (d.p.c.) (step I), accumulation of blood cells expressing different sets of surface markers to this region at 16.5-17.0 d.p.c. (step II), and entry of CD3+ and B220+ lymphocytes just before birth (step III). PP formation of both Il7ra-/- and Lta-/- mice is impaired from step I, suggesting involvement of the two molecules at the same timing in PP organogenesis. Expression of lymphotoxin (LT) alpha and LTbeta in IL-7 receptor (IL-7R) alpha+ cells in the intestine indicates that defects of Il7ra-/- and Lta-/- mice are due to functional inability of IL-7Ralpha+ cells in the induction of PP anlage. Blocking of IL-7Ralpha function by a single injection of the antagonistic mAb in 15.5 d.p.c. embryos suppressed appearance of VCAM-1(+) spots and expression of LTalpha and LTbeta in the intestine, which eventually resulted in mice without PP but are otherwise normal. Intestinal IL-7Ralpha+ cells are lymphoid in morphology but CD3(-) and functional in both nu/nu and Rag2-/- mice. These results implicate IL-7Ralpha+ CD3(-) cells as the direct inducer of the organizing center of PP.
Subsets of murine CD4+ T cells localize to different areas of the spleen after adoptive transfer. Naı̈ve and T helper 1 (TH1) cells, which express the chemokine receptor CCR7, are home to the periarteriolar lymphoid sheath, whereas activated TH2 cells, which lack CCR7, form rings at the periphery of the T cell zones near B cell follicles. Retroviral transduction of
TH2 cells with CCR7 forces them to localize in a TH1-like pattern and inhibits their participation in B cell help in vivo but not in vitro. Thus, differential expression of
chemokine receptors results in unique cellular migration patterns that are important for effective immune responses.
Proper lymph node (LN) development requires tumor necrosis factor-related activation-induced cytokine (TRANCE) expression. Here we demonstrate that the defective LN development in TRANCE(-/)- mice correlates with a significant reduction in lymphotoxin (LT)alphabeta(+)alpha(4)beta(7)(+)CD45(+)CD4(+)CD3(-) cells and their failure to form clusters in rudimentary mesenteric LNs. Transgenic TRANCE overexpression in TRANCE(-/)- mice results in selective restoration of this cell population into clusters, and results in full LN development. Transgenic TRANCE-mediated restoration of LN development requires LTalphabeta expression on CD45(+) CD4(+)CD3(-) cells, as LNs could not be induced in LTalpha(-/)- mice. LTalpha(-/)- mice also showed defects in the fate of CD45(+)CD4(+)CD3(-) cells similar to TRANCE(-/)- mice. Thus, we propose that both TRANCE and LTalphabeta regulate the colonization and cluster formation by CD45(+) CD4(+)CD3(-) cells in developing LNs, the degree of which appears to correlate with the state of LN organogenesis.
CD4+CD3- cells are the predominant hematopoietic cells found in mouse fetal intestine. We prove their role as Peyer's patch (PP)-inducing cells by transfer into neonatal PP-deficient mice. To test the requirement of chemokines and adhesion molecules in induction of PP, we studied mice deficient in CXCR5 and/or alpha4beta1 integrin-mediated adhesion. CXCR5-/- mice have CD4+CD3- cells, which are inefficient in inducing PP formation. We show here that CXCR5/CXCL13 signaling activates alpha4beta1 integrin on CD4+CD3- cells. Blocking of beta1 integrin or VCAM-1, the ligand of alpha4beta1 integrin, inhibits PP formation. This study demonstrates the link between chemokine receptors and adhesion molecules that regulates stromal/hematopoietic cell interaction leading to PP formation.
The development of lymphoid organs depends on the correct expression of several molecules within a defined timeframe during ontogeny. Although this is an extremely complex process, with each secondary lymphoid tissue requiring subtly different signals, a common framework for lymphoid development is beginning to emerge. Drawing on studies of lymph nodes, Peyer's patches and nasal-associated lymphoid tissue, an integrative model of lymphoid-tissue development, involving adhesion molecules, cytokines and chemokines, which emphasizes the role of interactions between CD3-CD4+CD45+ 'inducer' cells and VCAM1+ICAM1+ stromal 'organizer' cells is presented.
It is important to understand which molecules are relevant for linking innate and adaptive immune cells. In this study, we show that OX40 ligand is selectively induced on IL-2, IL-12, or IL-15-activated human NK cells following stimulation through NKG2D, the low affinity receptor for IgG (CD16) or killer cell Ig-like receptor 2DS2. CD16-activated NK cells costimulate TCR-induced proliferation, and IFN-gamma produced by autologous CD4+ T cells and this process is dependent upon expression of OX40 ligand and B7 by the activated NK cells. These findings suggest a novel and unexpected link between the natural and specific immune responses, providing direct evidence for cross-talk between human CD4+ T cells and NK receptor-activated NK cells.
Recently, we reported that a CD4(+)CD3(-)CD11c(-) accessory cell provided OX40-dependent survival signals to follicular T cells. These accessory cells express both OX40 ligand and CD30 ligand, and the receptors, OX40 and CD30, are both expressed on Th2-primed CD4 T cells. OX40 and CD30 signals share common signaling pathways, suggesting that CD30 signals might substantially compensate in OX40-deficient mice. In this report we have dissected the signaling roles of CD30 alone and in combination with OX40. CD30-deficient mice showed an impaired capacity to sustain follicular germinal center responses, and recall memory Ab responses were substantially reduced. Deficiencies in OX40 and CD30 signals were additive; secondary Ab responses were ablated in double-deficient mice. Although the initial proliferation of OX40/CD30 double-knockout OTII transgenic T cells was comparable to that of their normal counterparts, they failed to survive in vivo, and this was associated with reduced T cell numbers associated with CD4(+)CD3(-) cells in B follicles. Finally, we show that OX40/CD30 double-knockout OTII transgenic T cells fail to survive compared with normal T cells when cocultured with CD4(+)CD3(-) cells in vitro.
Lymphocytes from lymphotoxin (LT) alpha-deficient mice, which lack segregation of their B- and T-cell areas, acquire normal organization following adoptive transfer into RAG-deficient recipients, identifying a non-B non-T cell in the segregation process. Here we show that a CD4+CD3- accessory cell is tightly associated with discrete VCAM-1-expressing stromal cells in B- and T-cell areas of the mouse spleen. CD4+CD3- cells express high levels of LTalpha, LTbeta, and tumor necrosis factor (TNF) alpha, which are the ligands for the LTbeta receptor and TNFR1 expressed by stromal cells. The expression of these ligands is functional, as transferring CD4+CD3- cells derived from either embryonic or adult tissues into LTalpha-deficient mice organizes B/T segregation and up-regulates CCL21 protein expression in areas where T cells are segregated from B cells. We propose that the function of CD4+CD3- cells is to form a link between primed CD4 T cells and the underlying stromal elements, creating distinct microenvironments in which they enable effector responses.
CD30 and OX40 (CD134) are members of the TNFR superfamily expressed on activated CD4 T cells, and mice deficient in both these molecules harbor a striking defect in the capacity to mount CD4 T cell-dependent memory Ab responses. This article shows that these mice also fail to control Salmonella infection because both CD30 and OX40 signals are required for the survival but not commitment of CD4 Th1 cells. These signals are also needed for the survival of CD4 T cells activated in a lymphopenic environment. Finally, Salmonella and lymphopenia are shown to act synergistically in selectively depleting CD4 T cells deficient in OX40 and CD30. Collectively these findings identify a novel mechanism by which Th1 responses are sustained.
The formation of lymph nodes (LN) and Peyer's patches (PP) can be distinguished by the requirement of RANK for LN but not IL-7Rα, which is essential for PP development. However, lymphotoxin-αβ (LTαβ) signaling is required for both organs. The cellular basis underlying this dichotomy was revealed by the finding that the fetal IL-7Rα+ population responded equally well to IL-7 and RANKL to express LTαβ. IL-7Rα+ cells harvested from TRAF6−/− embryos expressed LTαβ in response to IL-7 but not RANKL, demonstrating that the RANK-TRAF6 signaling pathway regulates LTαβ expression in LN but not in PP. Soluble IL-7 administered to TRAF6−/− embryos was sufficient to restore LN genesis indicating the functional similarities of the IL-7Rα+ inducer cells for LN and PP genesis.
The natural cytotoxicity receptor NKp46 is an activating receptor expressed by several distinct innate lymphoid cell (ILC) subsets, including NK cells, some γδ T cells and intestinal RORγt(+) IL-22(+) cells (NCR22 cells, IL-22-producing NKp46(+) cell). NCR22 cells may play a role in mucosal barrier function through IL-22-mediated production of anti-bacterial peptides from intestinal epithelial cells. Previous studies identified a predominant proportion of NCR22 cells in gut cryptopatches (CP), lymphoid structures that are strategically positioned to collect and integrate signals from luminal microbes; however, whether CP or other lymphoid structures condition NCR22 cell differentiation is not known. Programmed and inducible lymphoid tissue development requires cell-surface-expressed lymphotoxin (LT)α(1) β(2) heterotrimers (provided by lymphoid tissue inducer (LTi) cells) to signal lymphotoxin-β receptor (LTR)(+) stromal cells. Here, we analyzed NCR22 cells in LTβR-deficient Ncr1(GFP/+) mice that lack organized secondary lymphoid tissues. We found that NCR22 cells develop in the absence of LTβR, become functionally competent and localize to the lamina propria under steady-state conditions. Following infection of LTβR(-/-) mice with the Gram-negative pathogen Citrobacter rodentium, IL-22 production from NCR22 cells was not affected. These results indicate that organized lymphoid tissue structures are not critical for the generation of an intact and fully functional intestinal NCR22 cell compartment.
Lymphoid tissue inducer (LTi) cells are essential for secondary lymphoid tissue development, and recently identified human LTi cells are closely related to natural killer (NK) cells. In this study, we investigate whether human CD3(-)CD117(+)CD56(-) cells that include LTi and immature NK cells respond to interleukin (IL)-15, which is an NK cell growth factor. In the presence of IL-15, CD3(-)CD117(+)CD56(-) cells proliferate and downregulate the expression of OX40L and mRNA for IL-22, lymphotoxin-alpha, and aryl hydrocarbon receptor, but not Id2. To examine whether CD(-)CD117(+)CD56(-) cells differentiate into CD3(-)CD117(+)CD56(+) NK cells by IL-15, we sorted CD3(-)CD117(+)CD56(-)OX40L(+) cells and cultured with IL-15 for 7 days. Approximately 75% of the cells differentiated into imterferon-gamma-expressing CD56(+) cells and approximately 25% of the cells did not. In addition, the latter population expressed LTi markers, including lymphotoxin-alpha and retinoid-related orphan receptor-gamma (RORC). These results show that approximately 25% of CD3(-)CD117(+)CD56(-)OX40L(+) cells are LTi cells and do not differentiate into CD56(+) NK cells by IL-15.
The key role of interleukin (IL)-23 in the pathogenesis of autoimmune and chronic inflammatory disorders is supported by the identification of IL-23 receptor (IL-23R) susceptibility alleles associated with inflammatory bowel disease, psoriasis and ankylosing spondylitis. IL-23-driven inflammation has primarily been linked to the actions of T-helper type 17 (TH17) cells. Somewhat overlooked, IL-23 also has inflammatory effects on innate immune cells and can drive T-cell-independent colitis. However, the downstream cellular and molecular pathways involved in this innate intestinal inflammatory response are poorly characterized. Here we show that bacteria-driven innate colitis is associated with an increased production of IL-17 and interferon-gamma in the colon. Stimulation of colonic leukocytes with IL-23 induced the production of IL-17 and interferon-gamma exclusively by innate lymphoid cells expressing Thy1, stem cell antigen 1 (SCA-1), retinoic-acid-related orphan receptor (ROR)-gammat and IL-23R, and these cells markedly accumulated in the inflamed colon. IL-23-responsive innate intestinal cells are also a feature of T-cell-dependent models of colitis. The transcription factor ROR-gammat, which controls IL-23R expression, has a functional role, because Rag-/-Rorc-/- mice failed to develop innate colitis. Last, depletion of Thy1+ innate lymphoid cells completely abrogated acute and chronic innate colitis. These results identify a previously unrecognized IL-23-responsive innate lymphoid population that mediates intestinal immune pathology and may therefore represent a target in inflammatory bowel disease.
Lymphoid tissue inducer cells (LTi) play an important role in the development of lymphoid tissue in embryos. Adult CD4(+)CD3(-) LTi-like cells present a similar phenotype and gene expression to their embryonic counterpart and have important roles in CD4(+) T-cell memory and lymphoid tissue recovery following viral infection. However, adult LTi-like cells are heterogeneous populations and the factors that regulate their survival and accumulation within secondary lymphoid organs remain unclear, in particular whether the T-zone stroma is involved. Here we report the identification and characterization of a distinct subset of podoplanin(+) murine splenic stromal cells that support adult LTi-like cell survival. We have identified and isolated CD45(-)podoplanin(+) stromal cell populations which have a similar but distinct phenotype to T-zone reticular cells in LN. CD45(-)podoplanin(+) fibroblast-like cells mediate LTi-like cell survival in vitro; surprisingly this was not dependent upon IL-7 as revealed through blocking Ab experiments and studies using LTi-like cells unable to respond to gamma chain cytokines. Our findings show that adult LTi-like cells require extrinsic signals from podoplanin(+) splenic stromal cells to survive and suggest that IL-7 is not necessary to mediate their survival in the adult spleen.
In this review, we summarize the current understanding of the multiple functions of the mouse lymphoid tissue inducer (LTi) cells in: (i) the development of organized lymphoid tissue, (ii) the generation and maintenance of CD4-dependent immunity in adult lymphoid tissues; and (iii) the regulation of central tolerance in thymus. By contrast with mouse LTi cells, which have been well described, the human equivalent is only just beginning to be characterized. Human LTi-like cells expressing interleukin (IL)-22 have been identified recently and found to differentiate into natural killer (NK) cells. The relationship of LTi cells to NK cells is discussed in the light of several studies reporting a close relationship in the mouse between LTi cells and transcription factor retinoid-related orphan receptor gammat-dependent IL-22 producing NK cells in the gut. We also outline our data suggesting that these cells are present in adult human lymphoid tissues.
Mucosal tissues, lying at the interface with the external environment, are constantly challenged by microbial, physical and chemical assaults. To provide the necessary immune defence to such challenges, lymph nodes and Peyer's patches are formed in utero in response to inductive signals from lymphoid-tissue inducer (LTi) cells. As discussed in this Progress article, a series of recent reports has identified a population of interleukin-22-producing mucosal cells in the gut and tonsils that share features with both LTi cells (by expressing RORgammat) and natural killer cells (by expressing NKp46) and that might be involved in immunity and homeostasis in mucosal tissues.
The human body contains over 500 individual lymph nodes, yet the biology of their formation is poorly understood. Here we identify human lymphoid tissue-inducer cells (LTi cells) as lineage-negative RORC+ CD127+ cells with the functional ability to interact with mesenchymal cells through lymphotoxin and tumor necrosis factor. Human LTi cells were committed natural killer (NK) cell precursors that produced interleukin 17 (IL-17) and IL-22. In vitro, LTi cells gave rise to RORC+ CD127+ NK cells that retained the ability to produce IL-17 and IL-22. Postnatally, similar populations of LTi cell-like cells and RORC+ CD127+ NK cells were present in tonsils, and both secreted IL-17 and IL-22 but no interferon-gamma. Our data indicate that lymph node organogenesis is controlled by an NK cell precursor population with adaptive immune features and demonstrate a previously unappreciated link between the innate and adaptive immune systems.
For a brief period during fetal lymph node organogenesis in mice, lymph node postcapillary high endothelial venules surprisingly express the Peyer's patch addressin MAdCAM-1. This expression allows initial seeding of this incipient structure by two unusual lymphocyte populations selectively expressing the Peyer's patch homing receptor integrin alpha4beta7: CD4+CD3- oligolineage progenitors and TCR gammadelta+ T cells. We show here that CD4+CD3- cells are lineage-restricted progenitors that express surface lymphotoxin-beta (LTbeta) and the chemokine receptor BLR1 and that can become natural killer cells, dendritic antigen-presenting cells, and follicular cells of unknown outcome, but these cells do not become T or B lymphocytes. Since the necessity of lymphotoxin in lymphoid organ development has been shown, we propose that the novel subset of CD4+CD3-LTbeta+ fetal cells is instrumental in the development of lymphoid tissue architecture.
Initiation of nasopharyngeal-associated lymphoid tissue (NALT) development is independent of the programmed cytokine cascade necessary for the formation of Peyer's patches (PP) and peripheral lymph nodes (PLN), a cytokine cascade which consists of IL-7R, LTalpha1beta2/LTbetaR, and NIK. However, the subsequent organization of NALT seems to be controlled by these cytokine signaling cascades since the maturation of NALT structure is generally incomplete in those cytokine cascade-deficient mice. NALT as well as PP and PLN are completely absent in Id2(-/-) mice. NALT organogenesis is initiated following the adoptive transfer of CD3(-)CD4(+)CD45(+) cells into Id2(-/-) mice, constituting direct evidence that CD3(-)CD4(+)CD45(+) inducer cells can provide an IL-7R-, LTalpha1beta2/LTbetaR-, and NIK-independent tissue organogenesis pathway for secondary lymphoid tissue development.
The formation of lymph nodes (LN) and Peyer's patches (PP) can be distinguished by the requirement of RANK for LN but not IL-7R(alpha), which is essential for PP development. However, lymphotoxin-alphabeta (LT(alpha)beta) signaling is required for both organs. The cellular basis underlying this dichotomy was revealed by the finding that the fetal IL-7R(alpha)(+) population responded equally well to IL-7 and RANKL to express LT(alpha)beta. IL-7R(alpha)(+) cells harvested from TRAF6(-/-) embryos expressed LTalphabeta in response to IL-7 but not RANKL, demonstrating that the RANK-TRAF6 signaling pathway regulates LT(alpha)beta expression in LN but not in PP. Soluble IL-7 administered to TRAF6(-/-) embryos was sufficient to restore LN genesis indicating the functional similarities of the IL-7R(alpha)(+) inducer cells for LN and PP genesis.
In this report we identify an accessory cell that interacts with primed and memory T cells at sites where they collaborate with B cells. These cells are distinguished from conventional dendritic cells by their lack of response to Flt3 ligand and their inability to process antigen. Unlike dendritic cells, the CD4(+)CD3(-) cells have little CD80 or CD86 expression but do express high levels of the TNF ligands, OX40 ligand and CD30 ligand. We show that Th2-primed cells express the receptors for these TNF ligands and preferentially survive when cocultured with these cells. Furthermore, we show that the preferential survival of OX40(+) T cells and support of memory T cell help for B cells are linked to their association with CD4(+)CD3(-) cells in vivo.
Lymphoid tissue inducer (LTi) cells have a well established role in secondary lymphoid tissue development. Here, we report on the heterogeneity of LTi cells based on their CD4 and chemokine receptor expression. The CD4(-) LTi-cell population has a similar phenotype to the CD4(+) population, with similar chemokine-receptor-expressing subsets. In both embryonic and adult spleen the CD4(-) LTi-cell population is comparable as a proportion of total splenocytes to its CD4(+) counterpart. In contrast, different proportions of CD4(+) and CD4(-) LTi cells are found in different lymph nodes. Both CD4(+) and CD4(-) LTi cells share the anatomical location and are associated with vascular cell adhesion molecule-1-positive stromal cells in spleen and lymph nodes. The numbers of both CD4(+) and CD4(-) LTi cells in adult spleen are augmented in the presence of B cells. With the exception of CD4, there is a strong correlation coefficient (0.89) for gene expression between the two populations. Polymerase chain reaction analysis of individual CD4(+) and CD4(-) LTi cells shows that a similar proportion in embryonic and adult spleen co-expressed both CXCR5 and CCR7 or CXCR5 alone: 84.6% for adult CD4(+) and 87.6% for adult CD4(-); 95.3% for embryonic CD4(+) and 91.5% for embryonic CD4(-). Consistently fewer CCR7 single-positive cells were found in the CD4(+) and CD4(-) fractions in the embryo.
AHR: aryl hydrocarbon receptor Á LTi: lymphoid tissue inducer Á TRANCE: tumor necrosis factor-related activation-induced cytokine Full correspondence
- Abbreviations
Abbreviations: AHR: aryl hydrocarbon receptor Á LTi: lymphoid tissue
inducer Á TRANCE: tumor necrosis factor-related activation-induced
cytokine
Full correspondence: Prof. Mi-Yeon Kim, Department of Bioinformatics
and Life Science, Soongsil University, Seoul 156-743, Korea
Fax: 182-2-824-4383
The survival of memory CD41
- D R Withers
- E Jaensson
- F Gaspal
- F M Mcconnell
- B Eksteen
- G Anderson
- W W Agace
- P J Lane
Withers, D. R., Jaensson, E., Gaspal, F., McConnell, F. M., Eksteen, B.,
Anderson, G., Agace, W. W. and Lane, P. J., The survival of memory CD41
T cells within the gut lamina propria requires OX40 and CD30 signals
T cells within the gut lamina propria requires OX40 and CD30 signals. J.
Immunol. 2009. 183: 5079-5084.