Epigenetic modulation of β-cells by interferon-α via PNPT11-miR-26a-TET2 triggers autoimmune diabetes [RNA-seq]
Ontology highlight
ABSTRACT: Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β-cell alterations in triggering the activation of self-reactive T-cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFNα, a cytokine associated with T1D development. We found that IFNα triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by up-regulation of the exoribonuclease, PNPase Old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the up-regulation of ten-eleven translocation TET2 enzyme and increased 5-hydoxymethylcytosine levels in human islets and pancreatic β-cells. Moreover, we showed that specific IFNα expression in the β cells of IFNα-INS1CreERT2 transgenic mice, led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFNα regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.
Project description:Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β-cell alterations in triggering the activation of self-reactive T-cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFNα, a cytokine associated with T1D development. We found that IFNα triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by up-regulation of the exoribonuclease, PNPase Old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the up-regulation of ten-eleven translocation TET2 enzyme and increased 5-hydoxymethylcytosine levels in human islets and pancreatic β-cells. Moreover, we showed that specific IFNα expression in the β cells of IFNα-INS1CreERT2 transgenic mice, led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFNα regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.
Project description:The pro-inflammatory cytokines IFNα, IFNγ, IL-1β and TNFα may contribute to innate and adaptive immune responses during islet inflammation (insulitis) in type 1 diabetes (T1D). We used deep RNA-sequencing analysis to characterize the response of human pancreatic beta cells to each cytokine individually and compared the signatures obtained with those present in islets of individuals affected by T1D. IFNα and IFNγ had a much greater impact on the beta cell transcriptome when compared to IL-1β and TNFα. The IFN-induced gene signatures have a strong correlation with those observed in beta cells from T1D patients, and the level of expression of specific IFN-stimulated genes is positively correlated with proteins present in islets of these individuals, regulating beta cell responses to “danger signals” such as viral infections. These data suggest that IFNα and IFNγ are the central cytokines at the islet level in T1D, contributing to the triggering and amplification of autoimmunity.
Project description:In type 1 diabetes (T1D), the appearance of multiple islet autoantibodies indicates the onset of islet autoimmunity, often many years before clinical symptoms arise. However, the underlying molecular mechanisms in T cells that can promote aberrant activation thereby triggering autoimmune progression remain poorly understood. Here, we show that during early stages of islet autoimmunity a miRNA142-3p/Tet2 signaling axis in murine and human CD4+T cells interferes with the efficient induction of regulatory T (Treg) cells accompanied by impairments in Treg stability. Specifically, we demonstrate that miR142-3p is induced in islet autoimmunity, while its inhibition enhances Treg induction and stability accompanied by a reduction of islet autoimmunity in non-obese diabetic (NOD) mice. Mechanistically, using HITS-CLIP analyses we identify the methylcytosine dioxygenase Tet2 as a direct target of miR142-3p in CD4+T cells, thereby linking high miR142-3p levels to epigenetic remodeling and impairments in Treg induction and stability. These findings offer a new mechanistic model where during islet-autoimmunity miR142-3p/Tet2-mediated Treg instability can contribute to autoimmune activation and progression.
Project description:In type 1 diabetes (T1D), the appearance of multiple islet autoantibodies indicates the onset of islet autoimmunity, often many years before clinical symptoms arise. However, the underlying molecular mechanisms in T cells that can promote aberrant activation thereby triggering autoimmune progression remain poorly understood. Here, we show that during early stages of islet autoimmunity a miRNA142-3p/Tet2 signaling axis in murine and human CD4+T cells interferes with the efficient induction of regulatory T (Treg) cells accompanied by impairments in Treg stability. Specifically, we demonstrate that miR142-3p is induced in islet autoimmunity, while its inhibition enhances Treg induction and stability accompanied by a reduction of islet autoimmunity in non-obese diabetic (NOD) mice. Mechanistically, using HITS-CLIP analyses we identify the methylcytosine dioxygenase Tet2 as a direct target of miR142-3p in CD4+T cells, thereby linking high miR142-3p levels to epigenetic remodeling and impairments in Treg induction and stability. These findings offer a new mechanistic model where during islet-autoimmunity miR142-3p/Tet2-mediated Treg instability can contribute to autoimmune activation and progression.
Project description:Type 1 diabetes (T1D) is one of the most prevalent autoimmune diseases among children in Western countries. Earlier metabolomics studies suggest that T1D is preceded by dysregulation of lipid metabolism. Here we used a lipidomics approach to analyze molecular lipids in a prospective series of 428 plasma samples from 40 children who progressed to T1D (PT1D), 40 children who developed at least a single islet autoantibody but did not progress to T1D during the follow-up (P1Ab) and 40 matched controls (CTR). Sphingomyelins were found to be persistently downregulated in PT1D when compared to the P1Ab and CTR groups. Triacylglycerols and phosphatidylcholines were mainly downregulated in PT1D as compared to P1Ab at the age of 3 months. Our study suggests that children who progressed to islet autoimmunity or overt T1D are characterized by distinct lipidomic signatures, which may be helpful in the identification of at-risk children before the initiation of autoimmunity.
Project description:Type 1 diabetes (T1D) is an autoimmune disease caused by selective destruction of insulin producing pancreatic beta-cells in the islets of the Langerhans. The progression to clinical diabetes is characterized by the appearance of autoantibodies against islet cells (ICA) and beta-cell-specific antigens (IAA, IA-2 and GADA), which are considered the first markers signifying onset of autoimmunity. The mechanisms initiating or enhancing the autoimmune process remain poorly understood. Transcriptomic profiling on whole blood samples provides an approach for monitoring T1D disease process. In these investigations of pathways that are changed during the disease process, we have analyzed RNA from longitudinal peripheral blood samples of children who have developed T1D associated autoantibodies and eventually clinical type 1 diabetes . All study subjects were participants of the Type 1 Diabetes Prediction and Prevention (DIPP) study in Finland (38). Whole-blood RNA samples were collected during periodic clinic visits, typically at 3 to 12 month intervals. 2.5 ml venous blood was drawn into PAXgene Blood RNA tubes (Becton-Dickinson) and stored at -70°C. T1D-associated autoantibodies were measured from blood samples taken at each visit. Prospective samples from 3 children who developed T1D (subjects T1D_1 - T1D_3) and 2 children who developed ICA (subjects ICA_1 and ICA_2) during the DIPP follow-up were selected to the present study. Control children for the T1D cases (subjects T1D_C1 - T1D_C2) were matched for age, gender, birth place and HLA-genotype, from families who have no first-degree relatives with T1D. All samples (n=60) were processed and hybridized on Affymetrix Human Genome U133 Plus 2.0 arrays.
Project description:The gastrointestinal ecosystem is a highly complex environment with a profound influence on human health. Inflammation in the gut, linked to an altered gut microbiome has been associated with the development of multiple human conditions including type 1 diabetes (T1D). Viruses infecting the gastrointestinal tract, especially enteroviruses, are also thought to play an important role in T1D pathogenesis possibly via overlapping mechanisms. Here, we apply an integrative approach to combine comprehensive faecal virome, microbiome and metaproteome data sampled before and at the onset of islet autoimmunity in 40 children. We show strong age and antibody related effects across the datasets. Mastadenovirus infection was associated with profound functional changes in the faecal metaproteome. Multiomic factor analysis modelling revealed proteins associated with carbohydrate transport from the genus Faecalibacterium were associated with islet autoimmunity. These findings demonstrate functional remodelling of the gut microbiota accompanies both islet autoimmunity and viral infection.
Project description:During the progression of type 1 diabetes (T1D), β-cells are exposed to significant stress and therefore require adaptive responses to survive. The adaptive mechanisms that can preserve β-cell function and survival in the face of autoimmunity remain unclear. Here we show that deletion of the unfolded protein response genes, Atf6α or Ire1α, in β-cells of NOD mice prior to insulitis generates a p21-driven early senescence phenotype and altered β-cell secretome that significantly enhances leukemia inhibitory factor-mediated recruitment of M2 macrophages to the islets. Consequently, M2 macrophages promote anti-inflammatory responses and immune surveillance that cause resolution of islet inflammation, removal of terminally senesced β-cells, reduction of β-cell apoptosis, and prevention of T1D. We further demonstrate that p21-mediated early senescence signature is conserved in residual β-cells of T1D patients. Our findings reveal a previously unrecognized link between β-cell UPR and senescence that, if leveraged, may represent a novel therapeutic strategy for T1D.
Project description:Type 1 diabetes (T1D) is a polygenic autoimmune disorder caused by autoreactive T cells that recognize pancreatic islet antigens and subsequently destroy insulin-producing β-cells. Pancreatic lymph nodes (PLN) are an essential site for the development of T1D, where tolerance to pancreatic self-antigens is first broken and the autoimmune responses are amplified. The purpose of this study was to identify candidate genes and pathways in the PLN that may contribute to the pathogenesis of T1D. Microarray analysis was performed on the PLN of human non-diabetic healthy controls (n=7) and at-risk autoantibody-positive subjects (n=13).
Project description:Through gene expression profiling in cultured lymphocytes and PBMCs from a large set of T1D patients and controls, we demonstrate that IL-1ra may protect against the development of islet autoimmunity and T1D through down-regulating a large number of inflammatory genes and pathways. Keywords: autoimmunity; IL-1Ra;Type 1 diabetes (T1D)