22 research outputs found
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MS AHI1 genetic risk promotes IFNγ+ CD4+ T cells
Objective: To study the influence of the Abelson helper integration site 1 (AHI1) locus associated with MS susceptibility on CD4+ T cell function. Methods: We characterized the chromatin state of T cells in the MS-associated AHI1 linkage disequilibrium (LD) block. The expression and the role of the AHI1 variant were examined in T cells from genotyped healthy subjects who were recruited from the PhenoGenetic Project, and the function of AHI1 was explored using T cells from Ahi1 knockout mice. Results: Chromatin state analysis reveals that the LD block containing rs4896153, which is robustly associated with MS susceptibility (odds ratio 1.15, p = 1.65 × 10−13), overlaps with strong enhancer regions that are present in human naive and memory CD4+ T cells. Relative to the rs4896153A protective allele, the rs4896153T susceptibility allele is associated with decreased AHI1 mRNA expression, specifically in naive CD4+ T cells (p = 1.73 × 10−74, n = 213), and we replicate this effect in an independent set of subjects (p = 2.5 × 10−9, n = 32). Functional studies then showed that the rs4896153T risk variant and the subsequent decreased AHI1 expression were associated with reduced CD4+ T cell proliferation and a specific differentiation into interferon gamma (IFNγ)–positive T cells when compared with the protective rs4896153A allele. This T cell phenotype was also observed in murine CD4+ T cells with genetic deletion of Ahi1. Conclusions: Our findings suggest that the effect of the AHI1 genetic risk for MS is mediated, in part, by enhancing the development of proinflammatory IFNγ+ T cells that have previously been implicated in MS and its mouse models
Vanin-1 Pantetheinase Drives Smooth Muscle Cell Activation in Post-Arterial Injury Neointimal Hyperplasia
The pantetheinase vanin-1 generates cysteamine, which inhibits reduced glutathione (GSH) synthesis. Vanin-1 promotes inflammation and tissue injury partly by inducing oxidative stress, and partly by peroxisome proliferator-activated receptor gamma (PPARγ) expression. Vascular smooth muscle cells (SMCs) contribute to neointimal hyperplasia in response to injury, by multiple mechanisms including modulation of oxidative stress and PPARγ. Therefore, we tested the hypothesis that vanin-1 drives SMC activation and neointimal hyperplasia. We studied reactive oxygen species (ROS) generation and functional responses to platelet-derived growth factor (PDGF) and the pro-oxidant diamide in cultured mouse aortic SMCs, and also assessed neointima formation after carotid artery ligation in vanin-1 deficiency. Vnn1−/− SMCs demonstrated decreased oxidative stress, proliferation, migration, and matrix metalloproteinase 9 (MMP-9) activity in response to PDGF and/or diamide, with the effects on proliferation linked, in these studies, to both increased GSH levels and PPARγ expression. Vnn1−/− mice displayed markedly decreased neointima formation in response to carotid artery ligation, including decreased intima:media ratio and cross-sectional area of the neointima. We conclude that vanin-1, via dual modulation of GSH and PPARγ, critically regulates the activation of cultured SMCs and development of neointimal hyperplasia in response to carotid artery ligation. Vanin-1 is a novel potential therapeutic target for neointimal hyperplasia following revascularization
Molecular prioritization strategies to identify functional genetic variants in the cardiovascular disease-associated expression QTL Vanin-1
There is now good evidence that non-coding sequence variants are involved in the heritability of many common complex traits. The current 'gold standard' approach for assessing functionality is the in vitro reporter gene assay to assess allelic differences in transcriptional activity, usually followed by electrophoretic mobility shift assays to assess allelic differences in transcription factor binding. Although widely used, these assays have inherent limitations, including the lack of endogenous chromatin context. Here we present a more contemporary approach to assessing functionality of non-coding sequence variation within the Vanin-1 (VNN1) promoter. By combining 'gold standard' assays with in vivo assessments of chromatin accessibility, we greatly increase our confidence in the statistically assigned functional relevance. The standard assays revealed the-137 single nucleotide variant to be functional but the-587 variant to have no functional relevance. However, our in vivo tests show an allelic difference in chromatin accessibility surrounding the-587 variant supporting strong functional potential at both sites. Our approach advances the identification of functional variants by providing strong in vivo biological evidence for function
DataSheet_1_Human regulatory memory B cells defined by expression of TIM-1 and TIGIT are dysfunctional in multiple sclerosis.zip
BackgroundRegulatory B cells (Bregs) play a pivotal role in suppressing immune responses, yet there is still a lack of cell surface markers that can rigorously identify them. In mouse models for multiple sclerosis (MS), TIM-1 or TIGIT expression on B cells is required for maintaining self-tolerance and regulating autoimmunity to the central nervous system. Here we investigated the activities of human memory B cells that differentially express TIM-1 and TIGIT to determine their potential regulatory function in healthy donors and patients with relapsing-remitting (RR) MS.MethodsFACS-sorted TIM-1+/-TIGIT+/- memory B (memB) cells co-cultured with allogenic CD4+ T cells were analyzed for proliferation and induction of inflammatory markers using flow cytometry and cytokine quantification, to determine Th1/Th17 cell differentiation. Transcriptional differences were assessed by SMARTSeq2 RNA sequencing analysis.ResultsTIM-1-TIGIT- double negative (DN) memB cells strongly induce T cell proliferation and pro-inflammatory cytokine expression. The TIM-1+ memB cells enabled low levels of CD4+ T cell activation and gave rise to T cells that co-express IL-10 with IFNγ and IL-17A or FoxP3. T cells cultured with the TIM-1+TIGIT+ double positive (DP) memB cells exhibited reduced proliferation and IFNγ, IL-17A, TNFα, and GM-CSF expression, and exhibited strong regulation in Breg suppression assays. The functional activity suggests the DP memB cells are a bonafide Breg population. However, MS DP memB cells were less inhibitory than HC DP memB cells. A retrospective longitudinal study of anti-CD20 treated patients found that post-treatment DP memB cell frequency and absolute number were associated with response to therapy. Transcriptomic analyses indicated that the dysfunctional MS-derived DP memB/Breg population exhibited increased expression of genes associated with T cell activation and survival (CD80, ZNF10, PIK3CA), and had distinct gene expression compared to the TIGIT+ or TIM-1+ memB cells.ConclusionThese findings demonstrate that TIM-1/TIGIT expressing memory B cell subsets have distinct functionalities. Co-expression of TIM-1 and TIGIT defines a regulatory memory B cell subset that is functionally impaired in MS.</p
Discovery of small molecule vanin inhibitors: new tools to study metabolism and disease
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111323.pdf (publisher's version ) (Closed access)Vanins are enzymes with pantetheinase activity and are presumed to play a role in the recycling of pantothenic acid (vitamin B5) from pantetheine. Pantothenic acid is an essential nutrient required to synthesize coenzyme A, a cofactor involved in many biological processes such as fatty acid synthesis and oxidation of pyruvate to fuel the citric acid cycle. Hydrolysis of pantetheine also liberates cysteamine, a known antioxidant. Vanin-1 is highly expressed in liver and is under transcriptional control of PPAR-alpha and nutritional status, suggesting a role in energy metabolism. The lack of potent and specific inhibitors of vanins has hampered detailed investigation of their function. We hereby report the design, synthesis, and characterization of a novel pantetheine analogue, RR6, that acts as a selective, reversible, and competitive vanin inhibitor at nanomolar concentration. Oral administration of RR6 in rats completely inhibited plasma vanin activity and caused alterations of plasma lipid concentrations upon fasting, thereby illustrating its potential use in chemical biology research