RESUMO
The immune-regulatory cytokine IL-10 plays a central role during innate and adaptive immune responses. IL-10 is elevated in the serum and tissues of patients with systemic lupus erythematosus (SLE), an autoimmune disorder characterized by autoantibody production, immune-complex formation, and altered cytokine expression. Because of its B cell-promoting effects, IL-10 may contribute to autoantibody production and tissue damage in SLE. We aimed to determine molecular events governing T cell-derived IL-10 expression in health and disease. We link reduced DNA methylation of the IL10 gene with increased recruitment of Stat family transcription factors. Stat3 and Stat5 recruitment to the IL10 promoter and an intronic enhancer regulate gene expression. Both Stat3 and Stat5 mediate trans-activation and epigenetic remodeling of IL10 through their interaction with the histone acetyltransferase p300. In T cells from SLE patients, activation of Stat3 is increased, resulting in enhanced recruitment to regulatory regions and competitive replacement of Stat5, subsequently promoting IL-10 expression. A complete understanding of the molecular events governing cytokine expression will provide new treatment options in autoimmune disorders, including SLE. The observation that altered activation of Stat3 influences IL-10 expression in T cells from SLE patients offers molecular targets in the search for novel target-directed treatment options.
Assuntos
Montagem e Desmontagem da Cromatina/genética , Interleucina-10/genética , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Fator de Transcrição STAT3/metabolismo , Linfócitos T/metabolismo , Ativação Transcricional/genética , Acetilação , Biologia Computacional , Metilação de DNA/genética , Proteína p300 Associada a E1A/metabolismo , Elementos Facilitadores Genéticos/genética , Histonas/metabolismo , Humanos , Interleucina-10/metabolismo , Lisina/metabolismo , Fosforilação , Ligação Proteica , Receptores de Antígenos de Linfócitos T/metabolismo , Fator de Transcrição STAT5/metabolismoRESUMO
TCR-αß(+)CD3(+)CD4(-)CD8(-) "double negative" T cells are expanded in the peripheral blood of patients with systemic lupus erythematosus (SLE) and lupus-prone mice. Double negative T cells have been claimed to derive from CD8(+) cells that down-regulate CD8 co-receptors and acquire a distinct effector phenotype that includes the expression of proinflammatory cytokines. This, along with the fact that double negative T cells have been documented in inflamed organs, suggests that they may contribute to disease expression and tissue damage. We recently linked the transcription factor cAMP responsive element modulator (CREM) α, which is expressed at increased levels in T cells from SLE patients and lupus prone MRL/lpr mice, with trans-repression of a region syntenic to the murine CD8b promoter. However, the exact molecular mechanisms that result in a stable silencing of both CD8A and CD8B genes remain elusive. Here, we demonstrate that CREMα orchestrates epigenetic remodeling of the CD8 cluster through the recruitment of DNA methyltransferase (DNMT) 3a and histone methyltransferase G9a. Thus, we propose that CREMα is essential for the expansion of double negative T cells in SLE. CREMα blockade may have therapeutic value in autoimmune disorders with DN T cell expansion.
Assuntos
Complexo CD3 , Antígenos CD8/biossíntese , Montagem e Desmontagem da Cromatina , Modulador de Elemento de Resposta do AMP Cíclico/metabolismo , Lúpus Eritematoso Sistêmico/metabolismo , Linfócitos T/metabolismo , Animais , Antígenos CD8/genética , Modulador de Elemento de Resposta do AMP Cíclico/genética , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , DNA Metiltransferase 3A , Feminino , Inativação Gênica , Antígenos de Histocompatibilidade/genética , Antígenos de Histocompatibilidade/metabolismo , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Humanos , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/patologia , Masculino , Camundongos , Camundongos Endogâmicos MRL lpr , Linfócitos T/patologiaRESUMO
Appropriate expression of IL-2 plays a central role during the priming and differentiation of T cells. A tight balance between IL-2 and the effector cytokine IL-17A is essential for immune homeostasis. Epigenetic mechanisms have been documented as a key component of cytokine regulation during lineage commitment. The molecular mechanisms that induce chromatin remodeling are less well understood. We investigated epigenetic regulators that mediate the diametric expression of IL-2 and IL-17A in naive, central memory, and effector memory CD4(+) T cells. We demonstrate that cAMP response modulator (CREM)α contributes to epigenetic remodeling of IL2 in effector memory T cells through the recruitment of DNMT3a. CREMα also reduces CpG-DNA methylation of the IL17A promoter. CREMα expression is regulated at the epigenetic level by CpG-DNA methylation, which allows increased CREMα expression in effector memory CD4(+) T cells. T cells from patients with systemic lupus erythematosus (SLE) express increased levels of CREMα and exhibit a phenotype that is similar to effector memory CD4(+) T cells with epigenetically predetermined expression patterns of IL-2 and IL-17A. We conclude that CREMα mediates epigenetic remodeling of the IL2 and IL17A gene during T-cell differentiation in favor of effector memory T cells in health and disease.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Modulador de Elemento de Resposta do AMP Cíclico/imunologia , Interleucina-17/imunologia , Interleucina-2/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/patologia , Linhagem da Célula/imunologia , Células Cultivadas , Ilhas de CpG/genética , Modulador de Elemento de Resposta do AMP Cíclico/genética , Modulador de Elemento de Resposta do AMP Cíclico/metabolismo , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/imunologia , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA , DNA Metiltransferase 3A , Citometria de Fluxo , Expressão Gênica , Células HEK293 , Humanos , Memória Imunológica/imunologia , Interleucina-17/genética , Interleucina-17/metabolismo , Interleucina-2/genética , Interleucina-2/metabolismo , Células Jurkat , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/patologiaRESUMO
T cell receptor-αß(+) CD3(+)CD4(-)CD8(-) "double-negative" T cells are expanded in the peripheral blood of patients with systemic lupus erythematosus and autoimmune lymphoproliferative syndrome. In both disorders, double-negative T cells infiltrate tissues, induce immunoglobulin production, and secrete proinflammatory cytokines. Double-negative T cells derive from CD8(+) T cells through down-regulation of CD8 surface co-receptors. However, the molecular mechanisms orchestrating this process remain unclear. Here, we demonstrate that the transcription factor cAMP-responsive element modulator α (CREMα), which is expressed at increased levels in T cells from systemic lupus erythematosus patients, contributes to transcriptional silencing of CD8A and CD8B. We provide the first evidence that CREMα trans-represses a regulatory element 5' of the CD8B gene. Therefore, CREMα represents a promising candidate in the search for biomarkers and treatment options in diseases in which double-negative T cells contribute to the pathogenesis.
Assuntos
Antígenos CD8/biossíntese , Linfócitos T CD8-Positivos/metabolismo , Modulador de Elemento de Resposta do AMP Cíclico/metabolismo , Inativação Gênica , Lúpus Eritematoso Sistêmico/metabolismo , Proteínas Repressoras/metabolismo , Elementos de Resposta , Complexo CD3/genética , Complexo CD3/imunologia , Complexo CD3/metabolismo , Antígenos CD4/genética , Antígenos CD4/imunologia , Antígenos CD4/metabolismo , Antígenos CD8/genética , Antígenos CD8/imunologia , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/patologia , Modulador de Elemento de Resposta do AMP Cíclico/genética , Modulador de Elemento de Resposta do AMP Cíclico/imunologia , Feminino , Humanos , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/patologia , Masculino , Proteínas Repressoras/genética , Proteínas Repressoras/imunologia , Transcrição Gênica/genética , Transcrição Gênica/imunologiaRESUMO
Th17 lymphocytes play a key role during immune responses against bacteria and fungi and are involved in the pathophysiology of multiple autoimmune disorders. The co-stimulatory molecules SLAMF3 and SLAMF6 have been implicated in the formation of Th17 phenotypes and IL-17A expression. Increased surface expression of SLAMF3 and SLAMF6 has been linked with disease activity in systemic lupus erythematosus. Here we demonstrate that in human total T lymphocytes the canonical CD28 and the non-canonical SLAMF3/SLAMF6 co-stimulatory pathways cooperate in the recruitment of the transcription factor NFAT1 to the IL17A promoter. Furthermore, the dominance of the SLAMF3/SLAMF6 pathway in inducing IL-17A production can be attributed to an increased nuclear abundance and recruitment of RORγt to the IL17A promoter. Thus, we have identified an additional mechanism that may be central for the specific control of IL17A gene regulation in systemic lupus erythematosus T lymphocytes.
Assuntos
Antígenos CD/imunologia , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/imunologia , Regiões Promotoras Genéticas/genética , Complexo Receptor-CD3 de Antígeno de Linfócitos T/imunologia , Receptores de Superfície Celular/imunologia , Linfócitos T/imunologia , Anticorpos/imunologia , Anticorpos/farmacologia , Antígenos CD/genética , Antígenos CD/metabolismo , Antígenos CD28/genética , Antígenos CD28/imunologia , Antígenos CD28/metabolismo , Células Cultivadas , Imunoprecipitação da Cromatina , Regulação da Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Humanos , Immunoblotting , Interleucina-17/genética , Interleucina-17/imunologia , Interleucina-17/metabolismo , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/metabolismo , Mutação , Fatores de Transcrição NFATC/genética , Fatores de Transcrição NFATC/imunologia , Fatores de Transcrição NFATC/metabolismo , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Ligação Proteica , Complexo Receptor-CD3 de Antígeno de Linfócitos T/genética , Complexo Receptor-CD3 de Antígeno de Linfócitos T/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária , Membro 1 da Família de Moléculas de Sinalização da Ativação Linfocitária , Linfócitos T/metabolismoRESUMO
Protein phosphatase 2A (PP2A), a serine/threonine phosphatase, has been shown to control T cell function. We found that in vitro-activated B cells and B cells from various lupus-prone mice and patients with systemic lupus erythematosus display increased PP2A activity. To understand the contribution of PP2A to B cell function, we generated a Cd19CrePpp2r1afl/fl (flox/flox) mouse which lacks functional PP2A only in B cells. Flox/flox mice displayed reduced spontaneous germinal center formation and decreased responses to T cell-dependent and T-independent antigens, while their B cells responded poorly in vitro to stimulation with an anti-CD40 antibody or CpG in the presence of IL-4. Transcriptome and metabolome studies revealed altered nicotinamide adenine dinucleotide (NAD) and purine/pyrimidine metabolism and increased expression of purine nucleoside phosphorylase in PP2A-deficient B cells. Our results demonstrate that PP2A is required for optimal B cell function and may contribute to increased B cell activity in systemic autoimmunity.