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Fusion between HTLV-1-infected cells (C91-PL) and DC-SIGN-expressing cells (HeLa and HEK): role of DC-SIGN in syncytium formation. (A to C) HeLa cells, transduced (B) or not (A) by DC-SIGN expression vector, were incubated with HTLV-1-infected lymphocytes (C91-PL) for 7 h (ratio, 1:1) and processed for Giemsa staining. In DC-SIGN-positive HeLa cells, the number and the size of syncytia were greater (B) than in negative controls (HeLa cells that did not express DC-SIGN) (A). (Magnification, ϫ 200.) (C) Quantification of the numbers of syncytia and the numbers of nuclei in DC-SIGN-positive cells and controls (DC-SIGN negative). (D to G) Similar results were obtained with HEK cells bearing an HTLV-1 LTR-GFP and transduced (E and G) or not (D and F) with DC-SIGN expression vector. In DC-SIGN-positive HEK cells, the number and the size of syncytia were greater (E and G) than in negative controls (HeLa cells that did not express DC-SIGN) (D and F), as shown by Giemsa staining (D and E) or by GFP fluorescence signal at 7 h after contact (F and G) (magnification, ϫ 400).
Source publication
Interactions between the oncogenic retrovirus human T-cell leukemia virus type 1 (HTLV-1) and dendritic cells (DCs) are poorly
characterized. We show here that monocyte-derived DCs form syncytia and are infected upon coculture with HTLV-1-infected lymphocytes.
We examined the role of DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), a C-type lecti...
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... an integrated HTLV-1 LTR coupled with a GFP reporter gene. Cell fusion was evaluated by syncytium formation between adherent cells and infected lymphocytes (C91-PL and MT2). C91-PL cells fused strongly with HeLa cells that expressed DC-SIGN. Very large syncytia that in- volved most of the cell monolayer were observed as early as 7 h after contact (Fig. 3B), whereas much smaller syncytia were observed when C91-PL cells were cultivated with control HeLa cells (Fig. 3A). Expression of DC-SIGN increased both the number of syncytia and their relative size (the number of nuclei per syncytium) (Fig. 3C). The activity of DC-SIGN in HTLV- 1-induced syncytium formation was associated with ...
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... adherent cells and infected lymphocytes (C91-PL and MT2). C91-PL cells fused strongly with HeLa cells that expressed DC-SIGN. Very large syncytia that in- volved most of the cell monolayer were observed as early as 7 h after contact (Fig. 3B), whereas much smaller syncytia were observed when C91-PL cells were cultivated with control HeLa cells (Fig. 3A). Expression of DC-SIGN increased both the number of syncytia and their relative size (the number of nuclei per syncytium) (Fig. 3C). The activity of DC-SIGN in HTLV- 1-induced syncytium formation was associated with increased Similar results were obtained with HEK(293T) cells contain- ing an integrated HTLV-1 LTR coupled with a GFP ...
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... large syncytia that in- volved most of the cell monolayer were observed as early as 7 h after contact (Fig. 3B), whereas much smaller syncytia were observed when C91-PL cells were cultivated with control HeLa cells (Fig. 3A). Expression of DC-SIGN increased both the number of syncytia and their relative size (the number of nuclei per syncytium) (Fig. 3C). The activity of DC-SIGN in HTLV- 1-induced syncytium formation was associated with increased Similar results were obtained with HEK(293T) cells contain- ing an integrated HTLV-1 LTR coupled with a GFP reporter gene (40). Fusion with infected C91-PL cells was estimated either by Giemsa staining or by detection of a GFP fluorescent ...
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... either by Giemsa staining or by detection of a GFP fluorescent signal 7 h after contact. After fusion, the viral Tax-1 protein expressed in infected cells efficiently transactivated the LTR- driven reporter gene. The degree of syncytium formation, de- termined by phase-contrast microscopy and Giemsa staining, was greater in DC-SIGN-positive cells (Fig. 3E) than in control cells (Fig. 3D). The number of GFP-positive cells or syncytia counted in 30 randomly selected microscopic fields from two different cultures was fivefold greater in cultures in which DC- SIGN was expressed (112 in DC-SIGN-positive and 23 in DC- SIGN-negative cells). More GFP expression was observed 7 h after contact in ...
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... detection of a GFP fluorescent signal 7 h after contact. After fusion, the viral Tax-1 protein expressed in infected cells efficiently transactivated the LTR- driven reporter gene. The degree of syncytium formation, de- termined by phase-contrast microscopy and Giemsa staining, was greater in DC-SIGN-positive cells (Fig. 3E) than in control cells (Fig. 3D). The number of GFP-positive cells or syncytia counted in 30 randomly selected microscopic fields from two different cultures was fivefold greater in cultures in which DC- SIGN was expressed (112 in DC-SIGN-positive and 23 in DC- SIGN-negative cells). More GFP expression was observed 7 h after contact in HEK cells that expressed DC-SIGN ...
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... (Fig. 3D). The number of GFP-positive cells or syncytia counted in 30 randomly selected microscopic fields from two different cultures was fivefold greater in cultures in which DC- SIGN was expressed (112 in DC-SIGN-positive and 23 in DC- SIGN-negative cells). More GFP expression was observed 7 h after contact in HEK cells that expressed DC-SIGN (Fig. 3G) than in control cells (Fig. 3F). Syncytium formation increased with time: in many instances, a cytopathic effect linked to fusion led to detachment of the syncytia in DC-SIGN-positive cells 24 h after contact (data not ...
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... cells or syncytia counted in 30 randomly selected microscopic fields from two different cultures was fivefold greater in cultures in which DC- SIGN was expressed (112 in DC-SIGN-positive and 23 in DC- SIGN-negative cells). More GFP expression was observed 7 h after contact in HEK cells that expressed DC-SIGN (Fig. 3G) than in control cells (Fig. 3F). Syncytium formation increased with time: in many instances, a cytopathic effect linked to fusion led to detachment of the syncytia in DC-SIGN-positive cells 24 h after contact (data not ...
Similar publications
Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are related deltaretroviruses but are distinct in their disease-inducing capacity. These viruses can infect a variety of cell types, but only T lymphocytes become transformed, which is defined in vitro as showing indefinite interleukin-2-independent growth. Studies have indicated that HTLV-1 ha...
The retrovirus human T cell leukemia virus (HTLV) type I (HTLV-I) is primarily transmitted by breast-feeding or sexual contact, by cell-to-cell contact between T cells. TGF-beta, which has been shown to enhance transmission of HTLV-I in vitro, is found at high levels in breast milk and semen. In this study, the ability of TGF-beta to regulate expre...
Citations
... Other emerging targets for HTLV-1 therapy include DC-SIGN and apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) [177,178]. HTLV-1 transmission from DCs to T cells is shown to be primarily mediated by DC-SIGN; blocking of DC-SIGN with anti-DC-SIGN monoclonal antibodies is shown to prevent HTLV-1 transmission from DCs to T cells and decrease the number and size of HTLV-1-induced syncytial formation [130,179]. APOBEC3 enzymes are host-antiviral restriction factors, yet the mechanism is not fully understood. Paradoxically, HTLV-1 tax expression induced increased levels of A3C, A3D, A3F, A3G, and A3H expression in humanized mouse spleen cells [180]. ...
Dendritic cells (DCs) function as a link between innate and adaptive immune responses. Retroviruses HIV-1 and HTLV-1 modulate DCs to their advantage and utilize them to propagate infection. Coinfection of HTLV-1 and HIV-1 has implications for cancer malignancies. Both viruses initially infect DCs and propagate the infection to CD4+ T cells through cell-to-cell transmission using mechanisms including the formation of virologic synapses, viral biofilms, and conduits. These retroviruses are both neurotrophic with neurovirulence determinants. The neuropathogenesis of HIV-1 and HTLV-1 results in neurodegenerative diseases such as HIV-associated neurocognitive disorders (HAND) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Infected DCs are known to traffic to the brain (CNS) and periphery (PNS, lymphatics) to induce neurodegeneration in HAND and HAM/TSP patients. Elevated levels of neuroinflammation have been correlated with cognitive decline and impairment of motor control performance. Current vaccinations and therapeutics for HIV-1 and HTLV-1 are assessed and can be applied to patients with HIV-1-associated cancers and adult T cell leukemia/lymphoma (ATL). These diseases caused by co-infections can result in both neurodegeneration and cancer. There are associations with cancer malignancies and HIV-1 and HTLV-1 as well as other human oncogenic viruses (EBV, HBV, HCV, HDV, and HPV). This review contains current knowledge on DC sensing of HIV-1 and HTLV-1 including DC-SIGN, Tat, Tax, and current viral therapies. An overview of DC interaction with oncogenic viruses including EBV, Hepatitis viruses, and HPV is also provided. Vaccines and therapeutics targeting host–pathogen interactions can provide a solution to co-infections, neurodegeneration, and cancer.
... This study also highlights that the cross-talk between PMNs and infected DCs is mediated by DC-SIGN. Several reports underscore the multifaceted role of DC-SIGN in immune functions of DCs, including recognition and binding to carbohydrate motifs found on several pathogens, other leukocytes, and even self-antigens (26)(27)(28)(29)(30). Our data demonstrate that L. amazonensis infection is associated with a significant reduction in DC-SIGN expression, which is rescued in the presence of activated PMNs. ...
Background
Leishmaniasis is a neglected arthropod-borne disease that affects millions of people worldwide. Successful Leishmania infections require the mitigation of immune cell functions leading to parasite survival and proliferation. A large body of evidence highlights the involvement of neutrophils (PMNs) and dendritic cells (DCs) in the establishment of immunological responses against these parasites. However, few studies, contemplate to what extent these cells interact synergistically to constrain Leishmania infection.
Objective
We sought to investigate how PMNs and infected DCs interact in an in vitro model of Leishmania amazonensis infection.
Material and Methods
Briefly, human PMNs and DCs were purified from the peripheral blood of healthy donors. Next, PMNs were activated with fibronectin and subsequently co-cultured with L. amazonensis-infected DCs.
Results
We observed that L. amazonensis-infected DC exhibited lower rates of infection when co-cultivated with either resting or activated PMNs. Surprisingly, we found that the release of neutrophil enzymes was not involved in Leishmania killing. Next, we showed that the interaction between PMNs and infected-DCs was intermediated by DC-SIGN, further suggesting that parasite elimination occurs in a contact-dependent manner. Furthermore, we also observed that TNFα and ROS production was dependent on DC-SIGN-mediated contact, as well as parasite elimination is dependent on TNFα production in the co-culture. Finally, we observed that direct contact between PMNs and DCs are required to restore the expression of DC maturation molecules during L. amazonensis infection.
Conclusion
Our findings suggest that the engagement of direct contact between PMNs and L. amazonensis-infected DC via DC-SIGN is required for the production of inflammatory mediators with subsequent parasite elimination and DC maturation.
... 50-52 HTLV-1 transmission occurs mainly through cell-to-cell contacts rather than cell-free virus particles. 53,54 In addition, HTLV-1-infected T-cells can multiply by clonal expansion, consequently increasing the viral burden without the need for virus replication and reinfection. 55,56 To develop effective antiretroviral treatments for HTLV-1, it is paramount to gain a more complete understanding of the molecular processes that govern HTLV-1 replication. ...
Retroviral Gag targeting to the plasma membrane (PM) for assembly is mediated by the N-terminal matrix (MA) domain. For many retroviruses, Gag–PM interaction is dependent on phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, it has been shown that for human T-cell leukemia virus type 1 (HTLV-1), Gag binding to membranes is less dependent on PI(4,5)P2 than HIV-1, suggesting that other factors may modulate Gag assembly. To elucidate the mechanism by which HTLV-1 Gag binds to the PM, we employed NMR techniques to determine the structure of unmyristoylated MA (myr(–)MA) and to characterize its interactions with lipids and liposomes. The MA structure consists of four α-helices and unstructured N- and C-termini. We show that myr(–)MA binds to PI(4,5)P2 via the polar head and that binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups on the inositol ring, indicating that the MA–IP binding is governed by charge–charge interactions. The IP binding site was mapped to a well-defined basic patch formed by lysine and arginine residues. Using an NMR-based liposome binding assay, we show that PI(4,5)P2 and phosphatidylserine enhance myr(–)MA binding in a synergistic fashion. Confocal microscopy data revealed formation of puncta on the PM of Gag expressing cells. However, G2A-Gag mutant, lacking myristoylation, is diffuse and cytoplasmic. These results suggest that although myr(–)MA binds to membranes, myristoylation appears to be key for formation of HTLV-1 Gag puncta on the PM. Altogether, these findings advance our understanding of a key mechanism in retroviral assembly.
... Even though they share ~ 70% nucleotide identity and have a similar genome structure, HTLV-1 is considered more pathogenic as it is associated with adult T-cell leukemia and HTLV-1 associated myelopathy/tropical spastic paraparesis (49)(50)(51). HTLV-1 transmission occurs mainly through cell-to-cell contacts rather than cell-free virus particles (52,53). In addition, HTLV-1 infected T-cells can multiply by clonal expansion, consequently increasing the viral burden without the need for virus replication and reinfection (54,55). ...
During the late phase of retroviral replication, the virally encoded Gag polyprotein is targeted to the plasma membrane (PM) for assembly. GagPM binding is mediated by the N-terminal matrix (MA) domain of Gag. For many retroviruses, Gag binding to the PM was found to be dependent on phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. However, it was shown that for human T-cell leukemia virus type 1 (HTLV-1), Gag binding to membranes is less dependent on PI(4,5)P2, suggesting that other factors may modulate Gag assembly. To elucidate the mechanism by which HTLV-1 Gag binds to the PM, we employed NMR techniques to solve the structure of unmyristoylated MA (myr(−)MA) and to characterize its interactions with lipids and liposomes. The MA structure consists of four α-helices and unstructured N- and C-termini. We show that myr(−)MA binds to PI(4,5)P2 via the polar head and that myr(−)MA binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups on the inositol ring, indicating that the MAIP binding is governed by chargecharge interactions. The IP binding site was mapped to a well-defined basic patch formed by lysine and arginine residues. Using a sensitive NMR-based liposome binding assay, we show that myr(−)MA binding to membranes is significantly enhanced by phosphatidylserine (PS). Confocal microscopy data show that Gag is localized to the inner leaflet of the PM of infected cells, while the Gag G2A mutant, lacking myristoylation, is diffuse and cytoplasmic. These findings advance our understanding of a key mechanism in retroviral assembly.
... Conversely, infected CD4+ T-cells can also infect DCs via VS (albeit to a lesser extent because of the low expression of LFA-1 on DCs compared to activated CD4+ T-cells), establishing a bidirectional viral transmission route (Shimauchi et al., 2019). This process is mediated by HTLV-1 binding to lectin DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN) and ICAM-2 and ICAM-3 on target cells (Ceccaldi et al., 2006). In these cells, antigen presentation by MHC-II is also associated with the spontaneous proliferation of lymphocytes (Macatonia et al., 1992). ...
HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) is a neuropathological disorder in 1–3% of individuals infected with Human T-lymphotropic virus 1 (HTLV-1). This condition is characterized by progressive spastic lower limb weakness and paralysis, lower back pain, bladder incontinence, and mild sensory disturbances resembling spinal forms of multiple sclerosis. This disease also causes chronic disability and is therefore associated with high health burden in areas where HTLV-1 infection is endemic. Despite various efforts in understanding the virus and discovery of novel diagnostic markers, and cellular and viral interactions, HAM/TSP management is still unsatisfactory and mainly focused on symptomatic alleviation, and it hasn’t been explained why only a minority of the virus carriers develop HAM/TSP. This comprehensive review focuses on host and viral factors in association with immunopathology of the disease in hope of providing new insights for drug therapies or other forms of intervention.
... Virus is very efficiently transmitted from DCs to T cells either without or via de novo infection (41). In particular C-type lectins, such as DCspecific ICAM-3-grabbing non-integrin (DC-SIGN), expressed on DCs is implicated in the transfer of HIV-1 to T cells in the LNs (31,(42)(43)(44)(45) [rev. in (34)]. In case of opsonized HIV, the DC-SIGN-dependent interactions play a minor role for the attachment of HIV-1 to DCs as well as the DC-mediated HIVinfection (46). ...
Upon entry of human immunodeficiency virus 1 (HIV-1) into the host, innate immune mechanisms are acting as a first line of defense, that considerably also modify adaptive immunity by the provision of specific signals. Innate and adaptive immune responses are intimately linked and dendritic cells (DCs) together with complement (C) play an important role in regulation of adaptive immunity. Initially, the role of complement was considered to primarily support – or COMPLEMENT - cytolytic actions of antibodies or antibody-complexed antigens (immune complexes, ICs) or directly kill the pathogens by complement-mediated lysis. Recently, the role of complement was revised and found to significantly augmenting and modulating adaptive immunity, in particular against viruses. Complement and DCs are therefore predestined to open novel avenues for antiviral research and potential therapeutic interventions. Recent studies on interactions of complement-opsonized HIV-1 with DCs demonstrated a high potential of such primed DCs to initiate efficient antiviral and cytotoxic anti-HIV-1 immunity and complement-coated viral particles shift DCs functions via CR3 and CR4 in an antithetic manner. This review will focus on our current knowledge of CR3 and CR4 actions on DCs during HIV-1 binding and the outcome of infection influenced by entry and signaling pathways.
... However, the most likely hypothesis presented in a recent paper [4] is that the CD209 molecule is a potential receptor for the bovine leukemia virus. Moreover, mutations in the cd209 gene are associated with resistance to infection with the human T-cell leukemia virus [5]. In this paper, we present a crispr/Cas9-based cattle genome editing system for creating a cd209 knockout. ...
Bovine leukemia virus (BLV) causes enzootic leukemia - a chronic infectious disease occurring against the background of embedding the virus in the genome of B-lymphocytes and leading to malignization, invasion of tumor cells in organs and the formation of tumors. The disease is common in the United States, Japan, and Asia. In Russia, up to 30% is infected with BLV. Moreover, there is evidence of the presence of antibodies to the BLV virus in some groups of people, and the relationship between BLV and cancer in humans is widely discussed. All this indicates an urgent need to study BLV and create breeds resistant to it. The development of approaches to solving this problem is complicated by the fact that the receptor through which the infection is carried out is still unknown. Recently, it has been suggested that the virus penetrates the animal's lymphocytes using the CD209 molecule. In this paper, we propose a genome editing system based on CRISPR/Cas9 to get a knockout for this gene. We assume that animals obtained using the presented genome editing system will be resistant to infection with the bovine leukemia virus.
... To validate these in vivo results, several groups performed in vitro exposure of blood macrophages, myDC, monocytes, monocytes derived DC (MDDC) or pDC to HTLV-1 [29,[35][36][37][38][39][40][41][42][43]. Dendritic cells-derived from monocytes generate larger amount of DC, compared to DC purified from blood or extracted from mucosa, that are furthermore transcriptionally and functionally close to myeloid DC [44]. ...
... As expected, all in vitro infected DCs were shown to produce HTLV-1 viral particles, detected in the supernatant using Gag p24 detection kit [39] or in cell cytoplasm using imaging after p24 immunostaining [41] or using flow cytometry after Tax immunostaining [43]. Productively infected DC can transmit HTLV-1 to T-cells [39,42,43]. ...
Human T cell leukemia virus type 1 (HTLV-1), the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and the demyelinating neuroinflammatory disease known as HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP), was the first human retrovirus to be discovered. T-cells, which represent the main reservoir for HTLV-1, have been the main focus of studies aimed at understanding viral transmission and disease progression. However, other cell types such as myeloid cells are also target of HTLV-1 infection and display functional alterations as a consequence. In this work, we review the current investigations that shed light on infection, transmission and functional alterations subsequent to HTLV-1 infection of the different myeloid cells types, and we highlight the lack of knowledge in this regard.
... CD209 (dendritic cell-specific intracellular adhesion molecule (ICAM)-3 grabbing non integrin) is of particular interest, as it is the only molecule related to human Т-cell leukaemia virus infection among all identified molecules [15,16]. Polymorphism of the CD209 promoter has been shown to be associated with human Т leukaemia virus infection [17]. ...
... (Elsevier) dependent neutral amino acid transporter 1 receptors [14]. These three proteins are expressed in most cell types, including blood cells, and thus cannot be viewed as potential BLV receptors as the virus specific intracellular 3 grabbing nonar interest, as it is the only cell leukaemia virus infection among all identified molecules [15,16]. Polymorphism of the CD209 promoter has been shown to be associated with human Т-cell leukaemia virus infection [17]. ...
The bovine leukemia virus (BLV) is widely spread all over the world. Currently, treatment of leukemia-infected animals is not carried out. Not all virus carriers become ill with leukemia. The existing genetic resistance to the disease is due to the presence of alleles of resistance of the main histocompatibility complex. However, another mechanism of resistance is possible, which is associated with the penetration of the virus into the cell. The aim of the work was to analyze the currently available data on possible receptors of the virus. Four potential molecules were found. The results suggest that the potential BLV receptor is a CD209 protein.
... Специфичная для дендриных клеток межклеточная молекула адгезии (CD209, dendritic cell-specific intracellular adhesion molecules (ICAM)-3 grabbing non integrin) наиболее интересна, т.к. из всех выявленных это единственная молекула, связанная с инфекцией вируса Т-клеточного лейкоза человека [15,16]. Показана связь полиморфизма промотора гена CD209 с инфицированием вирусом Т-клеточного лейкоза человека [17]. ...
Вирус лейкоза крупного рогатого скота (ВЛКРС), являющийся причиной развития лейкоза, широко распространен во всем мире. В настоящее время нет подходов к лечению зараженных животных. Существующая генетическая устойчивость к заболеванию обуславливается двумя факторами: наличие аллелей устойчивости главного комплекса гистосовместимости и связанным с проникновением вируса в клетку неизвестным пока механизмом. Целью работы было провести анализ имеющихся на настоящий момент данных о возможных рецепторах вируса. Результаты работы дают основания полагать, что потенциальным рецептором ВЛКРС является белок CD209.
