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? Cell regeneration and modulation of Th cell subsets after lentivirus and dietary therapy with ?-3 PUFAs in diabetic NOD mice. Mice were sacrificed at 9 weeks of age following lentivirus treatment and DHA plus EPA dietary intervention, and pancreases were harvested. (A) Concentrations of nonfasting serum glucagon levels in nondiabetic mice; diabetic NOD mice (nonfasting blood glucose level for 2 consecutive weeks <20 mmol/l) before treatment; and diabetic NOD mice (nonfasting blood glucose level for 2 consecutive weeks >11.1 mmol/l) after ?-3 PUFA therapy (n = 5?7/group). *P < 0.05, **P < 0.01, and ***P < 0.0001 versus the nondiabetic group (Student's t test (34. AUTHOR: Added " (Student's t test) " here and in the B?D section below ? Correct?)). Data are representative of 2 independent experiments. (B?D) mRNA expression of Pdx1, Pax4, and Arx measured by RT-PCR in pancreases from NOD mice that received ?-3 PUFA therapy. *P < 0.05, **P < 0.01, and ***P < 0.0001 compared with the lenti-con group (n = 3 per group) (Student's t test). Data are representative of 3 independent experiments. (E?N) Quantification (n = 4?10 per group) of the percentage of intracellular staining of IFN-? + , IL-4 + , IL-7 + , and CD25 + FoxP3 + Th cells in LNs and spleens of diabetic NOD mice that received ?-3 PUFA therapy. Representative flow cytometric images are shown in Supplemental Figure 8. Data are representative of 3 independent experiments. *P < 0.05, **P < 0.01, and ***P < 0.0001 compared with the lenticon group (Student's t test). All values represent the mean ? SEM.
Source publication
Despite the benefit of insulin, blockade of autoimmune attack and regeneration of pancreatic islets are ultimate goals for the complete cure of type 1 diabetes (T1D). Long-term consumption of ?-3 polyunsaturated fatty acids (PUFAs) is known to suppress inflammatory processes, making these fatty acids candidates for the prevention and amelioration o...
Citations
... EFAs are essential for the integrity of skin and immune response and form precursors of several pro-and anti-inflammatory eicosanoids. EFAs are metabolized by enzymes desaturases (∆ 6 and ∆ 5 ) and elongases to form their long-chain metabolites: gamma-linolenic acid (GLA, EFAs are essential for the integrity of skin and immune response and form precursors of several pro-and anti-inflammatory eicosanoids. EFAs are metabolized by enzymes desaturases (Δ 6 and Δ 5 ) and elongases to form their long-chain metabolites: gamma-linolenic acid (GLA, 18:3 n-6), dihomo-GLA (DGLA, 20:3 n-6), and arachidonic acid (AA, 20:4 n-6) from LA and eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) from ALA. ...
... Thus, PUFAs form precursors to both pro-and antiinflammatory compounds. The balance between these pro-and anti-inflammatory compounds ultimately determines whether the inflammatory process continues or inflammation resolution occurs, leading to wound healing ( [4][5][6][7][8][9][10] and Figure 1). For the normal activity of desaturases, which are the rate-limiting steps in the metabolism of EFAs, several co-factors are needed. ...
... LXA4, resolvins, protectins, and maresins are potent suppressors of IL-6 and TNF-α. This close interaction(s) among PUFAs, eicosanoids, and cytokines seems to be crucial in the onset, continuation, and resolution of inflammation [4][5][6][7][8][9][10]. ...
I propose that a deficiency of essential fatty acids (EFAs) and an alteration in their (EFAs) metabolism could be a major factor in the pathogenesis of sepsis and sepsis-related mortality. The failure of corticosteroids, anti-TNF-α, and anti-interleukin-6 monoclonal antibodies can be attributed to this altered EFA metabolism in sepsis. Vitamin C; folic acid; and vitamin B1, B6, and B12 serve as co-factors necessary for the activity of desaturase enzymes that are the rate-limiting steps in the metabolism of EFAs. The altered metabolism of EFAs results in an imbalance in the production and activities of pro- and anti-inflammatory eicosanoids and cytokines resulting in both hyperimmune and hypoimmune responses seen in sepsis. This implies that restoring the metabolism of EFAs to normal may form a newer therapeutic approach both in the prevention and management of sepsis and other critical illnesses.
... Next, we investigated mechanisms by which LRP5-transported PUFAs regulate neutrophils. n-3 PUFAs have been shown to regulate mTORC1 [14][15][16][17][18] , and our IPA pathway enrichment analysis of differentially expressed genes revealed by total RNA sequencing of isolated bone marrow LRP5-null and WT neutrophils showed mTORC1 related signaling pathways (EIF2, eIF4-p70S6K, and mTOR signaling pathways) among the altered ones ( Supplementary Fig. 5a). Thus, we examined if LRP5 deficiency altered mTORC1 signaling activities. ...
... In addition, DHA also showed significant inhibition of S6K and S6 phosphorylation and histone citrullination in the WT, but not LRP5-null, neutrophils ( Supplementary Fig. 5d). ARA did not inhibit these mTORC1 signaling activities in neutrophils (Supplementary Fig. 5e), which is consistent with previous observations that ARA does not inhibit mTORC1 signaling in other cell types [14][15][16][17][18] . These results together indicate that n3-PUFAs inhibition of mTORC1 signaling and NET formation in neutrophils requires LRP5. ...
Polyunsaturated fatty acids (PUFAs), which cannot be synthesized by animals and must be supplied from the diet, have been strongly associated with human health. However, the mechanisms for their accretion remain poorly understood. Here, we show that LDL receptor-related protein 5 (LRP5), but not its homolog LRP6, selectively transports unesterified PUFAs into a number of cell types. The LDLa ligand-binding repeats of LRP5 directly bind to PUFAs and are required and sufficient for PUFA transport. In contrast to the known PUFA transporters Mfsd2a, CD36 and FATP2, LRP5 transports unesterified PUFAs via internalization to intracellular compartments including lysosomes, and n-3 PUFAs depend on this transport mechanism to inhibit mTORC1. This LRP5-mediated PUFA transport mechanism suppresses extracellular trap formation in neutrophils and protects mice from myocardial injury during ischemia-reperfusion. Thus, this study reveals a biologically important mechanism for unesterified PUFA transport to intracellular compartments.
... This reaction results in the release of fatty acids, such as ω-6, a precursor of prostaglandins, leukotrienes, and thromboxanes that have inflammatory and apoptotic actions, contributing to β-cell apoptosis [11][12][13]. Conversely, dietary supplementation with ω-3 fatty acids has been shown to reduce the risk of developing islet autoimmunity by 55% in humans and the development of diabetes in non-obese diabetic (NOD) mice by 60% [14,15]. Despite the latest development in this area, the role of the islet lipidome during the progression of T1D is poorly understood. ...
... MIN6 cells were a gift from the Yamagata lab, and were cultured in DMEM containing 4.5 g/L each of D-glucose and L-glutamine, 10% FBS, 100 units/mL penicillin, 100 μg/mL streptomycin and 50 mM 2-mercaptoethanol maintained at 37 °C in a 5% CO 2 atmosphere [20,21]. For knockdown experiments, cells were transfected using Lipofectamine RNAiMAX (Invitrogen) with SMARTpool ON-TARGETplus non-targeting siRNA (Dharmacon, cat#D-001810- [10][11][12][13][14][15][16][17][18][19][20] or siRNA targeting Pla2g6, Adprhl2 (Dharmacon, cat# L-051819-01-0020), and Suz12 (Dharmacon, cat# L-040180-00-0005) for varying hours, followed by cytokine cocktail 2 (CT2: 100 ng/ mL IFN-γ: R&D, cat#485-MI-100, 10 ng/mL TNF-α: R&D, Cat#410-MT-010, and 5 ng/mL IL-1β: R&D, cat #401-ML-005) treatment for 24 h. Cells were treated at 80% confluency with 80 μM arachidonic acid (Cayman, CAS#506-32-1), linoleic acid (Cayman, CAS#60-33-3), eicosapentaenoic acid (Cayman, CAS#10417-94-4), or docosahexaenoic acid (Cayman, CAS#6217-54-5) or equal volume of 100% ethanol (vehicle control) in combination with CT2 for 8 hrs. ...
... Therefore, shifting the fatty acid composition on the β-cell membrane may shift the balance towards protection against apoptotic signaling. Diet containing ω-3 fatty acids reduces the risk of islet autoimmunity in children [15] and the incidence of diabetes in NOD mice [14]. ω-3 fatty acids have been shown to reduce activation of T cells and macrophages [14,51] and to ameliorate the intestinal barrier [52] in NOD mice, but their action on β cells is not well understood. ...
Background
Lipids are regulators of insulitis and β-cell death in type 1 diabetes development, but the underlying mechanisms are poorly understood. Here, we investigated how the islet lipid composition and downstream signaling regulate β-cell death.
Methods
We performed lipidomics using three models of insulitis: human islets and EndoC-βH1 β cells treated with the pro-inflammatory cytokines interlukine-1β and interferon-γ, and islets from pre-diabetic non-obese mice. We also performed mass spectrometry and fluorescence imaging to determine the localization of lipids and enzyme in islets. RNAi, apoptotic assay, and qPCR were performed to determine the role of a specific factor in lipid-mediated cytokine signaling.
Results
Across all three models, lipidomic analyses showed a consistent increase of lysophosphatidylcholine species and phosphatidylcholines with polyunsaturated fatty acids and a reduction of triacylglycerol species. Imaging assays showed that phosphatidylcholines with polyunsaturated fatty acids and their hydrolyzing enzyme phospholipase PLA2G6 are enriched in islets. In downstream signaling, omega-3 fatty acids reduce cytokine-induced β-cell death by improving the expression of ADP-ribosylhydrolase ARH3. The mechanism involves omega-3 fatty acid-mediated reduction of the histone methylation polycomb complex PRC2 component Suz12, upregulating the expression of Arh3 , which in turn decreases cell apoptosis.
Conclusions
Our data provide insights into the change of lipidomics landscape in β cells during insulitis and identify a protective mechanism by omega-3 fatty acids.
... El síndrome del intestino permeable probablemente sea causado por los aditivos alimentarios industriales comúnmente utilizados en las dietas occidentalizadas actuales y los alimentos procesados (11,19,20). Además, un régimen alimentario occidentalizado es rico en grasas saturadas y AGPs omega-6, que ejercen propiedades proinflamatorias y pueden aumentar el riesgo de desarrollar enfermedades autoinmunes (11,21,22). Por otro lado, las dietas antiinflamatorias, ricas en fibras y ácidos grasos poliinsaturados omega-3 (como la dieta Mediterránea), podría prevenir el síndrome del intestino permeable y preservar la integridad de la barrera epitelial intestinal, así como la composición de la microbiota intestinal, lo que puede resultar en la prevención de enfermedades autoinmunes y otras enfermedades crónicas no transmisibles (11,21,23). ...
... Dichos estudios demostraron a su vez, que los PUFA omega-3 y omega-6 tienen un impacto opuesto en la regulación de los complejos mTOR, dictando así el destino de diferenciación de las células T CD4+ después del tratamiento con AGPs. En tanto, el EPA y DHA disminuyeron la fosforilación de la proteína ribosomal S6 (indicativo de la inhibición de la actividad de mTORC1), no así el AGP omega-6 AA que aumentó los niveles de fosforilación de la proteína S6 al activar mTORC1 (mammalian target of rapamycin complex 1) (22,59,63). Además, se demostró que las resolvinas de la serie D (RvD1 y RvD2) y la maresina 1 (MaR1) modulan las respuestas inmunitarias adaptativas en los linfocitos de sangre periférica humana: i) reduciendo la producción de citocinas por parte de las células T CD8+ activadas y las células Th1 y Th17 y ii) previniendo la diferenciación de células T CD4+ vírgenes en células Th1 y Th17, todo esto sin modular los receptores inhibidores de células T; ni anular a su capacidad para proliferar (64). ...
Resumen
Los trastornos autoinmunes representan una familia de al menos 80 condiciones diferentes que surgen de una respuesta aberrante del sistema inmunológico resultando finalmente en la destrucción de tejidos y órganos específicos del cuerpo. Es importante destacar que durante las últimas tres décadas los estudios epidemiológicos han proporcionado evidencia de un aumento constante en la incidencia y prevalencia de trastornos autoinmunes. En los últimos años, varios estudios han demostrado que la vitamina D y los ácidos grasos poliinsaturados (AGPs) omega-3 ejercen propiedades inmunomoduladoras y antiinflamatorias sinérgicas que pueden aprovecharse positivamente para la prevención y el tratamiento de trastornos autoinmunes. En este sentido, el reciente ensayo clínico denominado VITAL (ensayo de vitamina D y omega 3); un estudio a gran escala, aleatorizado, doble ciego, controlado con placebo encontró que la suplementación conjunta de vitamina D y AGPs omega-3 (VIDOM) puede reducir la incidencia de enfermedades autoinmunes. En esta revisión de la literatura, resumimos los mecanismos moleculares detrás de las propiedades inmunomoduladoras y antiinflamatorias de la vitamina D y los AGPs omega-3, así como la posible interacción bidireccional entre el metabolismo de la vitamina D y el metabolismo de los AGPs omega-3 que justifica la co- suplementación VIDOM en trastornos autoinmunes. Arch Latinoam Nutr 2023; 73(3): 223-232.
... The ω-3 fatty acids induce anti-inflammatory responses by activating the G-protein coupled receptor GPR120 (also known as free fatty acid receptor 4 -FFA4) ( Figure 3) [69,70], making this receptor an excellent target for drug discovery. β-cell death caused by infiltration of autoreactive CD8+ T cells can be prevented by restoring the T helper (Th)1/Th2 ratio balance administrating ω-3 fatty acids or resolvins, which reduce the population of Th1 cells and increase the populations of Th2 and regulatory T cells [71]. The ω-3 fatty acids also attenuate the inflammatory state of macrophages by reducing the activation of the inflammasome and production of nitric oxide [72,73]. ...
... Child's higher intake of total and ω-3 fatty acids decreases by up to 55% in risk for developing islet autoimmunity in prospective cohort studies [116,117]. Similarly, dietary DHA and EPA have been shown to reduce the onset of T1D in 60% of NOD mice [71]. In the DAISY study, ω-3 fatty acid content in erythrocytes showed a protective association with islet autoimmunity development over a 6-year followup [117], while, in the TEDDY study, erythrocyte EPA and DHA content at 3 months of age was protectively associated with IA risk [119]. ...
Introduction:
Type 1 diabetes (T1D) is an autoimmune disease in which pro-inflammatory and cytotoxic signaling drive the death of the insulin-producing β cells. This complex signaling is regulated in part by fatty acids and their bioproducts, making them excellent therapeutic targets.
Areas covered:
We provide an overview of the fatty acid actions on β cells by discussing how they can cause lipotoxicity or regulate inflammatory response during insulitis. We also discuss how diet can affect the availability of fatty acids and disease development. Finally, we discuss development avenues that need further exploration.
Expert opinion:
Fatty acids, such as hydroxyl fatty acids, ω-3 fatty acids, and their downstream products, are druggable candidates that promote protective signaling. Inhibitors and antagonists of enzymes and receptors of arachidonic acid and free fatty acids, along with their derived metabolites, which cause pro-inflammatory and cytotoxic responses, have the potential to be developed as therapeutic targets also. Further, because diet is the main source of fatty acid intake in humans, balancing protective and pro-inflammatory/cytotoxic fatty acid levels through dietary therapy may have beneficial effects, delaying T1D progression. Therefore, therapeutic interventions targeting fatty acid signaling hold potential as avenues to treat T1D.
... This reaction results in the release of fatty acids, such as ω-6, a precursor of prostaglandins, leukotrienes, and thromboxanes that have in ammatory and apoptotic actions, contributing to β-cell apoptosis [11][12][13]. Conversely, dietary supplementation with ω-3 fatty acids has been shown to reduce the risk of developing islet autoimmunity by 55% in humans and the development of diabetes in non-obese diabetic (NOD) mice by 60% [14,15]. Despite the latest development in this area, the role of the islet lipidome during the progression of T1D is poorly understood. ...
... MIN6 beta cell line culture and treatment MIN6 cells were cultured in DMEM containing 10% FBS and 1% penicillin-streptomycin and maintained at 37 ºC in a 5% CO 2 atmosphere. For knockdown experiments, cells were transfected using Lipofectamine RNAiMAX (Invitrogen) with SMARTpool ON-TARGETplus non-targeting siRNA (Dharmacon, cat#D-001810- [10][11][12][13][14][15][16][17][18][19][20] or siRNA targeting Pla2g6, Adprhl2 (Dharmacon, cat# L-051819-01-0020), and Suz12 (Dharmacon, cat# L-040180-00-0005) for varying hours, followed by cytokine cocktail 2 (CT2: 100 ng/mL IFN-γ: R&D, cat#485-MI-100, 10 ng/mL TNF-α: R&D, Cat#410-MT-010, and 5 ng/mL IL-1β: R&D, cat #401-ML-005) treatment for 24 h. For arachidonic acid (Cayman, CAS#506-32-1), linoleic acid (Cayman, CAS#60-33-3), eicosapentaenoic acid (Cayman, CAS#10417-94-4), and docosahexaenoic acid (Cayman, CAS#6217-54-5) treatment, cells were treated at 80% con uency, with 80 µM of respective lipids. ...
... Therefore, shifting the fatty acid composition on the β-cell membrane may shift the balance towards protection against apoptotic signaling. Diet containing ω-3 fatty acids reduces the incidence of diabetes in children [15] and NOD mice [14]. ω-3 fatty acids have been shown to reduce activation of T cells and macrophages [14,47] and to ameliorate the intestinal barrier [48] in NOD mice, but their action on β cells is not well understood. ...
Background
Lipids have been implicated as regulators of insulitis and β-cell death in type 1 diabetes development, but the underlying mechanisms are poorly understood. Here, we investigated how the islet lipid composition and downstream signaling regulate β-cell death.
Methods
We performed lipidomics using three models of insulitis: human islets and EndoC-βH1 β cells treated with the pro-inflammatory cytokines interlukine-1β and interferon-γ, and islets from pre-diabetic non-obese mice. We also performed mass spectrometry and fluorescence imaging to determine the localization of lipids and enzyme in islets. RNAi, apoptotic assay and qPCR were performed to determine the role of a specific factor in lipid-mediated cytokine signaling.
Results
Across all three models, lipidomic analyses showed a consistent increase of lysophosphatidylcholine species and phosphatidylcholines with polyunsaturated fatty acids and a reduction of triacylglycerol species. Imaging assays showed that phosphatidylcholine with polyunsaturated fatty acids and converting enzyme phospholipase PLA2G6 are enriched in islets. In downstream signaling, omega-3 fatty acids reduce cytokine-induced β-cell death by improving the expression of adenosine diphosphate ribosylhydrolase ARH3. The mechanism involves omega-3 fatty acid-induced degradation of the histone methylation polycomb complex PRC2 component Suz12, releasing the expression of Arh3, which in turn reduces cell apoptosis.
Conclusions
Our data provide insights into the change of lipidomics landscape in β cells during insulitis and identify a protective mechanism by omega-3 fatty acids.
... n − 3 PUFAs negatively regulate T-cell proliferation and IL-2 production, both of which are driven by n − 6 PUFAs [97]. Non-obese diabetic mice fed on an ARA-enriched diet exhibit increased proportions of Th1 and Th17 cells and decreased proportions of Th2 and Foxp3 + Treg cells accompanied with elevated concentrations of ARA metabolites, including 15-hydroxyeicosatetraenoic acids (HETE) and 20-HETE, in the spleen [98]. Accordingly, the levels of TNF-α, IFN-γ, and IL-17 are elevated in the plasma of these mice. ...
... Accordingly, the levels of TNF-α, IFN-γ, and IL-17 are elevated in the plasma of these mice. In contrast, diet enriched in DHA and EPA elicits the differentiation of Th2 and Foxp3 + Treg cells and suppresses the generation of Th1 and Th17 cells in non-obese diabetic mice [98]. In this context, some metabolites of DHA and EPA, such as resolvin D1, 16,17-epoxy docosapentaenoic acid, and prostaglandin (PG) D3, are increased in the spleen of the mice [98]. ...
... In contrast, diet enriched in DHA and EPA elicits the differentiation of Th2 and Foxp3 + Treg cells and suppresses the generation of Th1 and Th17 cells in non-obese diabetic mice [98]. In this context, some metabolites of DHA and EPA, such as resolvin D1, 16,17-epoxy docosapentaenoic acid, and prostaglandin (PG) D3, are increased in the spleen of the mice [98]. These findings suggest that n − 6 PUFAs are implicated in the pathogenesis of IBD through initiating Th1 and Th17 responses, whereas n − 3 PUFAs protect against intestinal pathology through inducing Foxp3 + Treg cells. ...
The intestinal tract harbors diverse microorganisms, host- and microbiota-derived metabolites, and potentially harmful dietary antigens. The epithelial barrier separates the mucosa, where diverse immune cells exist, from the lumen to avoid excessive immune reactions against microbes and dietary antigens. Inflammatory bowel disease (IBD), such as ulcerative colitis and Crohn's disease, is characterized by a chronic and relapsing disorder of the gastrointestinal tract. Although the precise etiology of IBD is still largely unknown, accumulating evidence suggests that IBD is multifactorial, involving host genetics and microbiota. Alterations in the metabolomic profiles and microbial community are features of IBD. Advances in mass-spectrometry-based lipidomic technologies enable identification of changes in the composition of intestinal lipid species in IBD. Because lipids have a wide range of functions, including signal transduction and cell membrane formation, dysregulation of lipid metabolism drastically affects the physiology of the host and microorganisms. Therefore, a better understanding of the intimate interactions of intestinal lipids with host cells that are implicated in the pathogenesis of intestinal inflammation might aid in the identification of novel biomarkers and therapeutic targets for IBD. This review summarizes the current knowledge on the mechanisms by which host and microbial lipids control and maintain intestinal health and diseases. This article is protected by copyright. All rights reserved.
... EAE disease score (F) and flow cytometric analysis of the frequency of CD4 + FOXP3 + cells in the lymph nodes (G). Data are represented as the mean ± SEM. **P < 0.01, calculated with Tukey's post hoc analysis previous studies have shown that DHA and synthetic PPARγ agonists promote the differentiation and maintenance of Tregs and reduce neuroinflammation in experimental animal models [41,[52][53][54][55][56][57]. Surprisingly, we found that PPARγ antagonism reduced EAE disease severity compared to that in the control mice. ...
The imbalance between pathogenic and protective T cell subsets is a cardinal feature of autoimmune disorders such as multiple sclerosis (MS). Emerging evidence indicates that endogenous and dietary-induced changes in fatty acid metabolism have a major impact on both T cell fate and autoimmunity. To date, however, the molecular mechanisms that underlie the impact of fatty acid metabolism on T cell physiology and autoimmunity remain poorly understood. Here, we report that stearoyl-CoA desaturase-1 (SCD1), an enzyme essential for the desaturation of fatty acids and highly regulated by dietary factors, acts as an endogenous brake on regulatory T-cell (Treg) differentiation and augments autoimmunity in an animal model of MS in a T cell-dependent manner. Guided by RNA sequencing and lipidomics analysis, we found that the absence of Scd1 in T cells promotes the hydrolysis of triglycerides and phosphatidylcholine through adipose triglyceride lipase (ATGL). ATGL-dependent release of docosahexaenoic acid enhanced Treg differentiation by activating the nuclear receptor peroxisome proliferator-activated receptor gamma. Our findings identify fatty acid desaturation by SCD1 as an essential determinant of Treg differentiation and autoimmunity, with potentially broad implications for the development of novel therapeutic strategies and dietary interventions for autoimmune disorders such as MS.
... In addition, PUFAs can also signal through cell surface G protein-coupled receptors including GPR40 and GPR120 [13]. Moreover, studies showed that n-3 PUFAs inhibited mTORC1 signaling [14][15][16][17][18]. The mTORC1 signaling pathways regulate numerous important cellular processes including stimulation of protein synthesis primarily through phosphorylation of p70S6 kinase 1 (S6K), S6 protein, and eIF4E Binding Protein (4EBP) [19]. ...
... Next, we investigated mechanisms by which LRP5-transported PUFAs regulate neutrophils. n-3 PUFAs have been shown to regulate mTORC1 [14][15][16][17][18], and our IPA pathway enrichment analysis of differentially expressed genes revealed by total RNA sequencing of isolated bone marrow LRP5-null and WT neutrophils showed mTORC1 related signaling pathways (EIF2, eIF4-p70S6K, and mTOR signaling pathways) among the altered ones (Fig. S5A). Thus, we examined if LRP5 deficiency altered (which was not certified by peer review) is the author/funder. ...
... In addition, DHA also showed significant inhibition of S6K and S6 phosphorylation and histone citrullination in the WT, but not LRP5-null, neutrophils (Fig. S5D). ARA did not inhibit these mTORC1 signaling activities in neutrophils ( Fig. S5E), which is consistent with previous observations that ARA does not inhibit mTORC1 signaling in other cell types [14][15][16][17][18]. These results together indicate that n3-PUFAs inhibition of mTORC1 signaling and NET formation in neutrophils requires LRP5. ...
Polyunsaturated fatty acids (PUFAs), which cannot be synthesized by animals and must be supplied from the diet, have been strongly associated with human health. However, the mechanisms for their accretion and actions remain poorly understood. Here, we show that LDL receptor-related protein 5 (LRP5), but not its homolog LRP6, selectively transports unesterified PUFAs into a number of cell types. The LDLa ligand-binding repeats of LRP5 directly bind to PUFAs and are required for PUFA transport. LRP5 transports PUFAs via internalization to intracellular compartments including lysosomes, and n-3 PUFAs depends on this transport mechanism to inhibit mTORC1. This LRP5-mediated PUFA transport mechanism suppresses neutrophil extracellular trap formation in neutrophils and protects mice from myocardial injury during ischemia-reperfusion. Thus, this study reveals a previously unknown and biologically important mechanism for PUFA transport and mTORC1 regulation.
... Previous reports indicated that specific diet regimens such as an omega-3 PUFA-enriched diet or a diet supplemented with tolerogenic metabolites (acetate, propionate) prevent T1D in humans and preclinical models (49)(50)(51). Those dietary regimens counter-regulate T1D possibly by promoting growth of beneficial bacteria and dampening intestinal inflammation (51, ...
Introduction
The integrity of the gut barrier (GB) is fundamental to regulate the crosstalk between the microbiota and the immune system and to prevent inflammation and autoimmunity at the intestinal level but also in organs distal from the gut such as the pancreatic islets. In support to this idea, we recently demonstrated that breakage of GB integrity leads to activation of islet-reactive T cells and triggers autoimmune Type 1 Diabetes (T1D). In T1D patients as in the NOD mice, the spontaneous model of autoimmune diabetes, there are alterations of the GB that specifically affect structure and composition of the mucus layer; however, it is yet to be determined whether a causal link between breakage of the GB integrity and occurrence of autoimmune T1D exists.
Methods
Here we restored GB integrity in the NOD mice through administration of an anti-inflammatory diet (AID- enriched in soluble fiber inulin and omega 3-PUFA) and tested the effect on T1D pathogenesis.
Results
We found that the AID prevented T1D in NOD mice by restoring GB integrity with increased mucus layer thickness and higher mRNA transcripts of structural (Muc2) and immunoregulatory mucins (Muc1 and Muc3) as well as of tight junction proteins (claudin1). Restoration of GB integrity was linked to reduction of intestinal inflammation (i.e., reduced expression of IL-1β, IL-23 and IL-17 transcripts) and expansion of regulatory T cells (FoxP3⁺ Treg cells and IL-10⁺ Tr1 cells) at the expenses of effector Th1/Th17 cells in the intestine, pancreatic lymph nodes (PLN) and intra-islet lymphocytes (IIL) of AID-fed NOD mice. Importantly, the restoration of GB integrity and immune homeostasis were associated with enhanced concentrations of anti-inflammatory metabolites of the ω3/ω6 polyunsaturated fatty acids (PUFA) and arachidonic pathways and modifications of the microbiome profile with increased relative abundance of mucus-modulating bacterial species such as Akkermansia muciniphila and Akkermansia glycaniphila.
Discussion
Our data provide evidence that the restoration of GB integrity and intestinal immune homeostasis through administration of a tolerogenic AID that changed the gut microbial and metabolic profiles prevents autoimmune T1D in preclinical models.
