RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Chronic liver disease can induce prolonged activation of hepatic stellate cells, which may result in liver fibrosis. Inactive rhomboid protein 2 (iRhom2) is required for the maturation of A disintegrin and metalloprotease 17 (ADAM17, also called TACE), which is responsible for the cleavage of membrane-bound tumor necrosis factor-α (TNF-α) and its receptors (TNFRs). Here, using the murine bile duct ligation (BDL) model, we showed that the abundance of iRhom2 and activation of ADAM17 increased during liver fibrosis. Consistent with this, concentrations of ADAM17 substrates were increased in plasma samples from mice after BDL and in patients suffering from liver cirrhosis. We observed increased liver fibrosis, accelerated disease progression, and an increase in activated stellate cells after BDL in mice lacking iRhom2 (Rhbdf2-/- ) compared to that in controls. In vitro primary mouse hepatic stellate cells exhibited iRhom2-dependent shedding of the ADAM17 substrates TNFR1 and TNFR2. In vivo TNFR shedding after BDL also depended on iRhom2. Treatment of Rhbdf2-/- mice with the TNF-α inhibitor etanercept reduced the presence of activated stellate cells and alleviated liver fibrosis after BDL. Together, these data suggest that iRhom2-mediated inhibition of TNFR signaling protects against liver fibrosis.
Assuntos
Proteínas de Transporte/genética , Colestase/genética , Cirrose Hepática/genética , Transdução de Sinais/genética , Proteína ADAM17/genética , Proteína ADAM17/metabolismo , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Ductos Biliares/cirurgia , Proteínas de Transporte/metabolismo , Células Cultivadas , Colestase/metabolismo , Etanercepte/farmacologia , Regulação da Expressão Gênica , Células Estreladas do Fígado/efeitos dos fármacos , Células Estreladas do Fígado/metabolismo , Humanos , Ligadura , Cirrose Hepática/metabolismo , Cirrose Hepática/prevenção & controle , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Receptores Tipo II do Fator de Necrose Tumoral/genética , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Persistent viral infections are characterized by the simultaneous presence of chronic inflammation and T cell dysfunction. In prototypic models of chronicity--infection with human immunodeficiency virus (HIV) or lymphocytic choriomeningitis virus (LCMV)--we used transcriptome-based modeling to reveal that CD4(+) T cells were co-exposed not only to multiple inhibitory signals but also to tumor-necrosis factor (TNF). Blockade of TNF during chronic infection with LCMV abrogated the inhibitory gene-expression signature in CD4(+) T cells, including reduced expression of the inhibitory receptor PD-1, and reconstituted virus-specific immunity, which led to control of infection. Preventing signaling via the TNF receptor selectively in T cells sufficed to induce these effects. Targeted immunological interventions to disrupt the TNF-mediated link between chronic inflammation and T cell dysfunction might therefore lead to therapies to overcome persistent viral infection.