RESUMO
Experimental autoimmune uveitis (EAU) induced by immunization of animals with retinal Ags is a model for human uveitis. The immunosuppressive cytokine IL-10 regulates EAU susceptibility and may be a factor in genetic resistance to EAU. To further elucidate the regulatory role of endogenous IL-10 in the mouse model of EAU, we examined transgenic (Tg) mice expressing IL-10 either in activated T cells (inducible) or in macrophages (constitutive). These IL-10-Tg mice and non-Tg wild-type controls were immunized with a uveitogenic regimen of the retinal Ag interphotoreceptor retinoid-binding protein. Constitutive expression of IL-10 in macrophages abrogated disease and reduced Ag-specific immunological responses. These mice had detectable levels of IL-10 in sera and in ocular extracts. In contrast, expression of IL-10 in activated T cells only partially protected from EAU and marginally reduced Ag-specific responses. All IL-10-Tg lines showed suppression of Ag-specific effector cytokines. APC from Tg mice constitutively expressing IL-10 in macrophages exhibited decreased ability to prime naive T cells, however, Ag presentation to already primed T cells was not compromised. Importantly, IL-10-Tg mice that received interphotoreceptor retinoid-binding protein-specific uveitogenic T cells from wild-type donors were protected from EAU. We suggest that constitutively produced endogenous IL-10 ameliorates the development of EAU by suppressing de novo priming of Ag-specific T cells and inhibiting the recruitment and/or function of inflammatory leukocytes, rather than by inhibiting local Ag presentation within the eye.
Assuntos
Doenças Autoimunes/imunologia , Proteínas do Olho/imunologia , Interleucina-10/imunologia , Retina/imunologia , Proteínas de Ligação ao Retinol/imunologia , Linfócitos T/imunologia , Uveíte/imunologia , Animais , Apresentação de Antígeno , Autoimunidade , Modelos Animais de Doenças , Interleucina-10/genética , Interleucina-10/metabolismo , Ativação Linfocitária , Macrófagos/imunologia , Macrófagos/metabolismo , Complexo Principal de Histocompatibilidade/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Linfócitos T/metabolismo , Uveíte/metabolismoRESUMO
IL-10 regulates inflammation by reducing cytokine and chemokine production from activated macrophages. We performed microarray experiments to identify possible effector molecules of IL-10 and to investigate the global effect of IL-10 on the transcriptional response induced in LPS-activated macrophages. To exclude background effects of endogenous IL-10, macrophages from IL-10-deficient mice were used. IL-10 up-regulated expression of a small number of genes (26 and 37 after 45 min and 3 h, respectively), including newly identified and previously documented targets such as suppressor of cytokine signaling-3 and IL-1 receptor antagonist. However, the activation program triggered by LPS was profoundly affected by IL-10. IL-10 repressed 62 and further increased 15 of 259 LPS-induced genes. For all genes examined, the effects of IL-10 were determined to be STAT3-dependent. These results suggest that IL-10 regulates STAT3-dependent pathways that selectively target a broad component of LPS-induced genes at the mRNA level.
Assuntos
Regulação da Expressão Gênica/imunologia , Interleucina-10/fisiologia , Ativação de Macrófagos/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Animais , Arginase/biossíntese , Células da Medula Óssea/citologia , Células da Medula Óssea/enzimologia , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Regulação para Baixo/genética , Regulação para Baixo/imunologia , Interleucina-10/antagonistas & inibidores , Interleucina-10/deficiência , Interleucina-10/genética , Interleucina-4/fisiologia , Interfase/genética , Interfase/imunologia , Lipopolissacarídeos/farmacologia , Ativação de Macrófagos/imunologia , Macrófagos/citologia , Macrófagos/enzimologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Receptores de Interleucina-4/biossíntese , Fator de Transcrição STAT3 , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Transativadores/deficiência , Transativadores/genética , Transativadores/fisiologia , Regulação para Cima/genética , Regulação para Cima/imunologiaRESUMO
IL-10 plays an essential role in blocking cytokine production by activated macrophages. To analyze the consequences of enforced expression of IL-10 by macrophages on innate and adaptive immune responses, we generated transgenic mice (macIL-10tg mice) expressing an epitope-tagged IL-10 (Flag-IL-10) under control of the human CD68 promoter. Expression of Flag-IL-10 was constitutive and restricted to macrophages, as shown by sorting splenocyte cell populations and intracellular staining for IL-10. Transgenic macrophages displayed suppressed production of TNF-alpha and IL-12 upon stimulation with LPS. When macIL-10tg mice were challenged with LPS, serum levels of proinflammatory cytokines were attenuated compared with controls. Infection with Mycobacterium bovis bacille Calmette-Guérin resulted in approximately 10-fold-higher bacterial loads than in wild-type mice. Normal T and B cell responses were observed in macIL-10tg mice, suggesting that macrophage-specific overexpression of IL-10 predominantly acts in an autocrine/paracrine manner, resulting in chronically deactivated macrophages that manifest an impaired ability to control pathogens.
