RESUMO
Activation of the NLRP3 inflammasome and subsequent maturation of IL-1ß have been implicated in acute lung injury (ALI), resulting in inflammation and fibrosis. We investigated the role of vimentin, a type III intermediate filament, in this process using three well-characterized murine models of ALI known to require NLRP3 inflammasome activation. We demonstrate that central pathophysiologic events in ALI (inflammation, IL-1ß levels, endothelial and alveolar epithelial barrier permeability, remodelling and fibrosis) are attenuated in the lungs of Vim(-/-) mice challenged with LPS, bleomycin and asbestos. Bone marrow chimeric mice lacking vimentin have reduced IL-1ß levels and attenuated lung injury and fibrosis following bleomycin exposure. Furthermore, decreased active caspase-1 and IL-1ß levels are observed in vitro in Vim(-/-) and vimentin-knockdown macrophages. Importantly, we show direct protein-protein interaction between NLRP3 and vimentin. This study provides insights into lung inflammation and fibrosis and suggests that vimentin may be a key regulator of the NLRP3 inflammasome.
Assuntos
Proteínas de Transporte/metabolismo , Inflamassomos/metabolismo , Inflamação/metabolismo , Vimentina/metabolismo , Lesão Pulmonar Aguda/metabolismo , Animais , Bleomicina/química , Células da Medula Óssea/citologia , Líquido da Lavagem Broncoalveolar , Linhagem Celular , Proliferação de Células , Feminino , Fibrose , Interleucina-1beta/metabolismo , Pulmão/metabolismo , Pulmão/patologia , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Knockout , Microscopia de Força Atômica , Proteína 3 que Contém Domínio de Pirina da Família NLR , Mapeamento de Interação de ProteínasRESUMO
Inflammation is essential for host defense but can cause tissue damage and organ failure if unchecked. How the inflammation is resolved remains elusive. Here we report that the transcription factor Miz1 was required for terminating lipopolysaccharide (LPS)-induced inflammation. Genetic disruption of the Miz1 POZ domain, which is essential for the transactivation or repression activity of Miz1, resulted in hyperinflammation, lung injury and greater mortality in LPS-treated mice but a lower bacterial load and mortality in mice with Pseudomonas aeruginosa pneumonia. Loss of the Miz1 POZ domain prolonged the expression of proinflammatory cytokines. After stimulation, Miz1 was phosphorylated at Ser178, which was required for recruitment of the histone deacetylase HDAC1 to repress transcription of the gene encoding C/EBP-δ, an amplifier of inflammation. Our data provide a long-sought mechanism underlying the resolution of LPS-induced inflammation.
Assuntos
Lesão Pulmonar Aguda/imunologia , Proteína delta de Ligação ao Facilitador CCAAT/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Inibidoras de STAT Ativados/metabolismo , Infecções por Pseudomonas/imunologia , Pseudomonas aeruginosa/imunologia , Lesão Pulmonar Aguda/genética , Animais , Citocinas/metabolismo , Repressão Enzimática/genética , Histona Desacetilase 1/metabolismo , Tolerância Imunológica , Inflamação/genética , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Mutagênese Sítio-Dirigida , Proteínas de Neoplasias/genética , Proteínas Nucleares/genética , Fosforilação , Proteínas Inibidoras de STAT Ativados/genética , Infecções por Pseudomonas/genética , Proteínas Repressoras/genética , Ativação Transcricional/genética , Ubiquitina-Proteína LigasesRESUMO
Elevated concentrations of CO2 (hypercapnia) lead to alveolar epithelial dysfunction by promoting Na,K-ATPase endocytosis. In the present report, we investigated whether the CO2/HCO3(-) activated soluble adenylyl cyclase (sAC) regulates this process. We found that hypercapnia increased the production of cyclic adenosine monophosphate (cAMP) and stimulated protein kinase A (PKA) activity via sAC, which was necessary for Na,K-ATPase endocytosis. During hypercapnia, cAMP was mainly produced in specific microdomains in the proximity of the plasma membrane, leading to PKA Type Iα activation. In alveolar epithelial cells exposed to high CO2 concentrations, PKA Type Iα regulated the time-dependent phosphorylation of the actin cytoskeleton component α-adducin at serine 726. Cells expressing small hairpin RNA for PKAc, dominant-negative PKA Type Iα, small interfering RNA for α-adducin, and α-adducin with serine 726 mutated to alanine prevented Na,K-ATPase endocytosis. In conclusion, we provide evidence for a new mechanism by which hypercapnia via sAC, cAMP, PKA Type Iα, and α-adducin regulates Na,K-ATPase endocytosis in alveolar epithelial cells.
