Project description:Atherosclerosis is a chronic inflammatory disease. Lesion progression is primarily mediated by cells of the monocyte/macrophage lineage. Interleukin-17A is a pro-inflammatory cytokine, which modulates immune cell trafficking and is involved inflammation in (auto)immune and infectious diseases. But the role of IL-17A still remains controversial. In the current study we investigated effects of IL-17A on advanced murine and human atherosclerosis, the common disease phenotype in clinical care. 26-weeks old apolipoprotein E-deficient (Apoe-/-) mice were fed a standard chow diet and treated either with IL-17A mAb (n=15) or irrelevant immunoglobulin (n=10) for 16 weeks. Furthermore, essential mechanisms of IL-17A in atherogenesis were studied in vitro. Inhibition of IL-17A markedly prevented atherosclerotic lesion progression (P=0.001) by reducing inflammatory burden and cellular infiltration (P=0.01) and improved lesion stability (P=0.01). In vitro experiments showed that IL-17A plays a role in chemoattractance, monocyte adhesion, sensitization of antigen-presenting cells toward pathogen-derived TLR4 ligands. Also, IL-17A induced a unique transcriptome pattern in monocyte-derived macrophages distinct from known macrophage types. Stimulation of human carotid plaque tissue ex vivo with IL-17A induced a pro-inflammatory milieu and up-regulation of molecules expressed by the IL-17A-induced macrophage subtype. We here show for the first time that functional blockade of IL-17A prevents atherosclerotic lesion progression and induces plaque stabilization in advanced lesions in Apoe-/- mice. The underlying mechanisms involve reduced inflammation and distinct effects of IL-17A on monocyte / macrophage lineage. In addition, translational experiments underline the relevance for the human system. Effects of IL-17A on human monocyte-derived macrophages were assessed (n=2 per group).
Project description:Atherosclerosis is a chronic inflammatory disease. Lesion progression is primarily mediated by cells of the monocyte/macrophage lineage. Interleukin-17A is a pro-inflammatory cytokine, which modulates immune cell trafficking and is involved inflammation in (auto)immune and infectious diseases. But the role of IL-17A still remains controversial. In the current study we investigated effects of IL-17A on advanced murine and human atherosclerosis, the common disease phenotype in clinical care. 26-weeks old apolipoprotein E-deficient (Apoe-/-) mice were fed a standard chow diet and treated either with IL-17A mAb (n=15) or irrelevant immunoglobulin (n=10) for 16 weeks. Furthermore, essential mechanisms of IL-17A in atherogenesis were studied in vitro. Inhibition of IL-17A markedly prevented atherosclerotic lesion progression (P=0.001) by reducing inflammatory burden and cellular infiltration (P=0.01) and improved lesion stability (P=0.01). In vitro experiments showed that IL-17A plays a role in chemoattractance, monocyte adhesion, sensitization of antigen-presenting cells toward pathogen-derived TLR4 ligands. Also, IL-17A induced a unique transcriptome pattern in monocyte-derived macrophages distinct from known macrophage types. Stimulation of human carotid plaque tissue ex vivo with IL-17A induced a pro-inflammatory milieu and up-regulation of molecules expressed by the IL-17A-induced macrophage subtype. We here show for the first time that functional blockade of IL-17A prevents atherosclerotic lesion progression and induces plaque stabilization in advanced lesions in Apoe-/- mice. The underlying mechanisms involve reduced inflammation and distinct effects of IL-17A on monocyte / macrophage lineage. In addition, translational experiments underline the relevance for the human system.
Project description:Two types of monocytes, inflammatory and patrolling, infiltrate the hearts in both human myocarditis and murine experimental autoimmune myocarditis (EAM) model. The fates and functions of these infiltrating monocytes governing the progression of heart failure remain unclear. Here, we created parabiotic EAM and naïve mice to show that cardiac inflammation facilitate monocyte-to-macrophage differentiation. Using a combination of flow cytometry, time lapsed imaging and transmission electron microscopy, we demonstrated in vitro that cardiac fibroblasts interact with monocytes and are instrumental in facilitating monocyte-to-macrophage differentiation. Moreover, IL-17A stimulated cardiac fibroblasts completely arrested Ly6Clo monocyte proliferation and inhibited both Ly6Chi and Ly6Clo monocyte-to-macrophage differentiation both in vitro and in vivo after intracardiac injections of monocytes into the hearts. Intriguingly, IL-17A signaling through cardiac fibroblasts also significantly downregulated Mer tyrosine kinase (MerTK) expressions on Ly6Chi monocyte-derived macrophages, thus jeopardizing their phagocytic abilities. Collectively, our results implicate divergent fates and functions of heart-infiltrating monocytes influenced by cardiac fibroblasts.
Project description:Background: It is recognized that atherosclerosis can regresses at least in animal models. However, little is known about the mechanisms. We induced regression of advanced atherosclerosis in apolipoprotein E deficient (APOE/) mice and studied underlying mechanisms. Unexpectedly, our study led to the role of interleukin-7 (IL-7) in atherogenesis. Methods and Results: We treated APOE/ mice fed a high cholesterol diet for 30 weeks to induce advanced lesions with a helper-dependent adenoviral vector expressing human apoE3 (HDAd-gE3), and analyzed the regression of atherosclerosis after 41 weeks. Using microarray analysis, we identified IL-7 as one of most significantly affected genes by lowering cholesterol. To answer why IL-7 is downregulated by reduced cholesterol, we studied effects of IL-7 on endothelial cells (ECs). Our major findings were (1) long-term lowering cholesterol induced regression of advanced atherosclerosis. (2) Microarray analysis identified multiple signaling pathways affected by lowering cholesterol. (3) Correction for multiple testing revealed that IL-7 expression was downregulated, whereas gamma-sarcoglycan and α-actin were upregulated. (4) Oxidized LDL upregulated IL-7 expression in macrophages but not in aorta ECs or smooth muscle cells. (5) IL-7 increased the expression of cell adhesion molecules and chemokine in ECs and promoted monocyte adhesion to ECs. (6) Systemic elevation of IL-7 induced inflammatory response and recruited monocyte/macrophage to the lesions without increasing plasma cholesterol. Conclusion: Our finding suggest that IL-7 inflames endothelium and triggers the adhesion/recruitment of monocyte/macrophages to the atherosclerotic lesions and thus plays a direct role in development of atherosclerosis. Key Words: arteriosclerosis, gene therapy, hypercholesterolemia, interleukins, cell adhesion molecules
Project description:Background: It is recognized that atherosclerosis can regresses at least in animal models. However, little is known about the mechanisms. We induced regression of advanced atherosclerosis in apolipoprotein E deficient (APOE/) mice and studied underlying mechanisms. Unexpectedly, our study led to the role of interleukin-7 (IL-7) in atherogenesis. Methods and Results: We treated APOE/ mice fed a high cholesterol diet for 30 weeks to induce advanced lesions with a helper-dependent adenoviral vector expressing human apoE3 (HDAd-gE3), and analyzed the regression of atherosclerosis after 41 weeks. Using microarray analysis, we identified IL-7 as one of most significantly affected genes by lowering cholesterol. To answer why IL-7 is downregulated by reduced cholesterol, we studied effects of IL-7 on endothelial cells (ECs). Our major findings were (1) long-term lowering cholesterol induced regression of advanced atherosclerosis. (2) Microarray analysis identified multiple signaling pathways affected by lowering cholesterol. (3) Correction for multiple testing revealed that IL-7 expression was downregulated, whereas gamma-sarcoglycan and α-actin were upregulated. (4) Oxidized LDL upregulated IL-7 expression in macrophages but not in aorta ECs or smooth muscle cells. (5) IL-7 increased the expression of cell adhesion molecules and chemokine in ECs and promoted monocyte adhesion to ECs. (6) Systemic elevation of IL-7 induced inflammatory response and recruited monocyte/macrophage to the lesions without increasing plasma cholesterol. Conclusion: Our finding suggest that IL-7 inflames endothelium and triggers the adhesion/recruitment of monocyte/macrophages to the atherosclerotic lesions and thus plays a direct role in development of atherosclerosis. Key Words: arteriosclerosis, gene therapy, hypercholesterolemia, interleukins, cell adhesion molecules Female APOE-/- mice (8 weeks of age) on a C57BL/6 background were purchased from Jackson Laboratory and were fed a diet containing 0.2% (w/w) cholesterol and 10% (v/w) coconut oil to induce atherosclerosis for 30 weeks. Mice were then divided into 3 groups, (n=15/group), treated with a tail vein injection of helper-dependent adenovirus expressing human apolipoprotein E3 (HDAd-gE3, 5 x 1012 viral particles/kg, n=11, vector), empty vector (HDAd-0, 5 x 1012 VP/kg, n=11, vector control) or phosphate buffered saline (PBS, vehicle) and sacrificed 10 days after. Three aortas extending sinus to arch were pooled for RNA extraction with an RNeasy kit (Qiagen). Sample ID 12031: E4: vector control (HDAd-0) 12043: E5: vector control 12046: V2: vector 12047: V3: vector 12048: V4: vector 12051: B1: vehicle (PBS) 12053: B3: vehicle 12054: B4: vehicle 12039: E3: vector control
Project description:IL-17A is a pro-inflammatory cytokine that promotes host defense against infections and contributes to the pathogenesis of chronic inflammatory diseases. Dendritic cells (DC) are antigen-presenting cells responsible for adaptive immune responses. Here, we report that IL-17A induces intense remodeling of lipid metabolism in human monocyte-derived DC, as revealed by microarrays analysis. In particular NR1H3/LXR-a and its target genes were significantly upregulated in response to IL-17A. IL-17A induced accumulation of Oil Red O-positive lipid droplets in DC leading to the generation of lipid-laden DC. A lipidomic study established that all the analyzed lipid species, i.e phospholipids, cholesterol, triglycerides, cholesteryl esters were elevated in IL-17A-treated DC. The increased expression of membrane lipid transporters in IL-17A-treated DC as well as their enhanced ability to uptake the fatty acid Bodipy-FL-C16 suggested that lipid uptake was the main mechanism responsible for lipid accumulation in response to IL-17A. IL-17A-induced lipid laden DC were able to stimulate allogeneic T cell proliferation in vitro as efficiently as untreated DC, indicating that IL-17A-treated DC are potently immunogenic. This study, encompassed in the field of immunometabolism, points out for the first time IL-17A as a modulator of lipid metabolism in DC and provides a rationale to delineate the importance of lipid-laden DC in IL-17A-related inflammatory diseases. We used microarrays analysis to understand the impact of IL-17A on human monocyte-derived human dendritic cells. We found overexpression of many genes involved in lipid metabolism in IL-17A-treated dendritic cells compared to untreated dendritic cells. In particular NR1H3/LXR-a and its target genes were significantly upregulated in response to IL-17A. IL-17A induced accumulation of Oil Red O-positive lipid droplets in DC leading to the generation of lipid-laden DC. A lipidomic study established that all the analyzed lipid species, i.e phospholipids, cholesterol, triglycerides, cholesteryl esters were elevated in IL-17A-treated DC. The increased expression of membrane lipid transporters in IL-17A-treated DC as well as their enhanced ability to uptake the fatty acid Bodipy-FL-C16 suggested that lipid uptake was the main mechanism responsible for lipid accumulation in response to IL-17A. IL-17A-induced lipid laden DC were able to stimulate allogeneic T cell proliferation in vitro as efficiently as untreated DC, indicating that IL-17A-treated DC are potently immunogenic. This study, encompassed in the field of immunometabolism, points out for the first time IL-17A as a modulator of lipid metabolism in DC and provides a rationale to delineate the importance of lipid-laden DC in IL-17A-related inflammatory diseases. RNA was extracted from untreated in vitro-generated DC at day 0 (DC, 4 biological replicates ) or DC cultured for 12 days with IL-17A, in the absence or presence of IFN-g (DC-17 and DC-G17, 5 biological replicates)
Project description:Interleukin-17 (IL-17) is a pleiotropic cytokine produced mainly by peripheral Th17 cells. Yet, brain functions of IL-17 derived from central nervous cells remain poorly understood. Here, we find an aberrant IL-17A signaling in the cerebellum of Fmr1-KO mice, a well-established genetic model for autism spectrum disorder (ASD). Cerebellar IL-17A, derived exclusively from microglia, is essential for the regulation of social behaviors by maintaining neuronal excitability and selectively suppressing inhibitory neurotransmission of Purkinje cells (PCs) in the cerebellar Crus I, a brain region critically involved in social cognition. Specific downregulation of IL-17 receptor-mediated signaling in cerebellar PCs recapitulates ASD-like social deficits and repetitive behaviors. Notably, both direct administration of IL-17A and induction of IL-17A release from cerebellar microglia by poly(I:C) effectively restore PC excitability and ameliorate ASD-like symptoms. The findings uncover an indispensable role of microglia-derived IL-17A for cerebellar social processing and suggest potential therapeutic strategies targeting IL-17A signaling for ASD.
Project description:Interleukin-17 (IL-17) is a pleiotropic cytokine produced mainly by peripheral Th17 cells. Yet, brain functions of IL-17 derived from central nervous cells remain poorly understood. Here, we find an aberrant IL-17A signaling in the cerebellum of Fmr1-KO mice, a well-established genetic model for autism spectrum disorder (ASD). Cerebellar IL-17A, derived exclusively from microglia, is essential for the regulation of social behaviors by maintaining neuronal excitability and selectively suppressing inhibitory neurotransmission of Purkinje cells (PCs) in the cerebellar Crus I, a brain region critically involved in social cognition. Specific downregulation of IL-17 receptor-mediated signaling in cerebellar PCs recapitulates ASD-like social deficits and repetitive behaviors. Notably, both direct administration of IL-17A and induction of IL-17A release from cerebellar microglia by poly(I:C) effectively restore PC excitability and ameliorate ASD-like symptoms. The findings uncover an indispensable role of microglia-derived IL-17A for cerebellar social processing and suggest potential therapeutic strategies targeting IL-17A signaling for ASD.
Project description:Circulating TRAIL is reduced in cardiovascular disease patients and TRAIL deletion in mice exacerbates disease. The source of TRAIL and protective mechanism(s) are unclear. Monocyte TRAIL mRNA was reduced from coronary artery disease patients, strikingly associating with reduced plasma TRAIL. A strong inverse correlation between plasma TRAIL and IL-18 was observed, with IL-18 repressing monocyte TRAIL mRNA. In mice, two sources were investigated using bone-marrow (BM) transplants; TRAIL expressed only in BM (BM-TRAIL) or everywhere except BM (parenchymal-TRAIL), vs. whole-body TRAIL ablation (null-TRAIL). BM-TRAIL attenuated macrophage content and atherosclerosis. BM-derived macrophages with TRAIL deletion were more inflammatory, with impaired migration and reduced expression of cholesterol efflux, efferocytosis and nitric oxide-controlling genes. TRAIL expression also reduced islet macrophage content, but only parenchymal-TRAIL islets had improved function. Recombinant TRAIL administration stimulated insulin expression and islet mass. We propose TRAIL maintains monocyte/macrophage homeostasis and limits the progression of atherosclerosis and islet dysfunction.
Project description:IL-17A is a pro-inflammatory cytokine that promotes host defense against infections and contributes to the pathogenesis of chronic inflammatory diseases. Dendritic cells (DC) are antigen-presenting cells responsible for adaptive immune responses. Here, we report that IL-17A induces intense remodeling of lipid metabolism in human monocyte-derived DC, as revealed by microarrays analysis. In particular NR1H3/LXR-a and its target genes were significantly upregulated in response to IL-17A. IL-17A induced accumulation of Oil Red O-positive lipid droplets in DC leading to the generation of lipid-laden DC. A lipidomic study established that all the analyzed lipid species, i.e phospholipids, cholesterol, triglycerides, cholesteryl esters were elevated in IL-17A-treated DC. The increased expression of membrane lipid transporters in IL-17A-treated DC as well as their enhanced ability to uptake the fatty acid Bodipy-FL-C16 suggested that lipid uptake was the main mechanism responsible for lipid accumulation in response to IL-17A. IL-17A-induced lipid laden DC were able to stimulate allogeneic T cell proliferation in vitro as efficiently as untreated DC, indicating that IL-17A-treated DC are potently immunogenic. This study, encompassed in the field of immunometabolism, points out for the first time IL-17A as a modulator of lipid metabolism in DC and provides a rationale to delineate the importance of lipid-laden DC in IL-17A-related inflammatory diseases. We used microarrays analysis to understand the impact of IL-17A on human monocyte-derived human dendritic cells. We found overexpression of many genes involved in lipid metabolism in IL-17A-treated dendritic cells compared to untreated dendritic cells. In particular NR1H3/LXR-a and its target genes were significantly upregulated in response to IL-17A. IL-17A induced accumulation of Oil Red O-positive lipid droplets in DC leading to the generation of lipid-laden DC. A lipidomic study established that all the analyzed lipid species, i.e phospholipids, cholesterol, triglycerides, cholesteryl esters were elevated in IL-17A-treated DC. The increased expression of membrane lipid transporters in IL-17A-treated DC as well as their enhanced ability to uptake the fatty acid Bodipy-FL-C16 suggested that lipid uptake was the main mechanism responsible for lipid accumulation in response to IL-17A. IL-17A-induced lipid laden DC were able to stimulate allogeneic T cell proliferation in vitro as efficiently as untreated DC, indicating that IL-17A-treated DC are potently immunogenic. This study, encompassed in the field of immunometabolism, points out for the first time IL-17A as a modulator of lipid metabolism in DC and provides a rationale to delineate the importance of lipid-laden DC in IL-17A-related inflammatory diseases.