RESUMO
The molecular mechanisms that link the sympathetic stress response and inflammation remain obscure. Here we found that the transcription factor Nr4a1 regulated the production of norepinephrine (NE) in macrophages and thereby limited experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Lack of Nr4a1 in myeloid cells led to enhanced NE production, accelerated infiltration of leukocytes into the central nervous system (CNS) and disease exacerbation in vivo. In contrast, myeloid-specific deletion of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, protected mice against EAE. Furthermore, we found that Nr4a1 repressed autocrine NE production in macrophages by recruiting the corepressor CoREST to the Th promoter. Our data reveal a new role for macrophages in neuroinflammation and identify Nr4a1 as a key regulator of catecholamine production by macrophages.
Assuntos
Sistema Nervoso Central/imunologia , Encefalomielite Autoimune Experimental/imunologia , Inflamação/imunologia , Macrófagos/imunologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/imunologia , Sistema Nervoso Simpático/imunologia , Animais , Linhagem Celular , Células Cultivadas , Sistema Nervoso Central/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Expressão Gênica/imunologia , Humanos , Inflamação/genética , Inflamação/metabolismo , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Esclerose Múltipla/imunologia , Esclerose Múltipla/patologia , Células Mieloides/imunologia , Células Mieloides/metabolismo , Norepinefrina/imunologia , Norepinefrina/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Coelhos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sistema Nervoso Simpático/metabolismo , Tirosina 3-Mono-Oxigenase/genética , Tirosina 3-Mono-Oxigenase/imunologia , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
T-cell receptor (TCR) triggering results in a cascade of intracellular tyrosine phosphorylation events that ultimately leads to T-cell activation. It is dependent on changes in the relative activities of membrane-associated tyrosine kinases and phosphatases near the engaged TCR. CD45 and CD148 are transmembrane tyrosine phosphatases with large ectodomains that have activatory and inhibitory effects on TCR triggering. This study investigates whether and how the ectodomains of CD45 and CD148 modulate their inhibitory effect on TCR signaling. Expression in T cells of forms of these phosphatases with truncated ectodomains inhibited TCR triggering. In contrast, when these phosphatases were expressed with large ectodomains, they had no inhibitory effect. Imaging studies revealed that truncation of the ectodomains enhanced colocalization of these phosphatases with ligated TCR at the immunological synapse. Our results suggest that the large ectodomains of CD45 and CD148 modulate their inhibitory effect by enabling their passive, size-based segregation from ligated TCR, supporting the kinetic-segregation model of TCR triggering.