RESUMO

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated to intermittent hypoxia (IH) and is an aggravating factor of non-alcoholic fatty liver disease (NAFLD). We investigated the effects of hypoxia in both in vitro and in vivo models of NAFLD. METHODS: Primary rat hepatocytes treated with free fatty acids (FFA) were subjected to chemically induced hypoxia (CH) using the hypoxia-inducible factor-1 alpha (HIF-1α) stabilizer cobalt chloride (CoCl2). Triglyceride (TG) content, mitochondrial superoxide production, cell death rates, cytokine and inflammasome components gene expression and protein levels of cleaved caspase-1 were assessed. Also, Kupffer cells (KC) were treated with conditioned medium (CM) and extracellular vehicles (EVs) from hypoxic fat-laden hepatic cells. The choline deficient L-amino acid defined (CDAA)-feeding model used to assess the effects of IH on experimental NAFLD in vivo. RESULTS: Hypoxia induced HIF-1α in cells and animals. Hepatocytes exposed to FFA and CoCl2 exhibited increased TG content and higher cell death rates as well as increased mitochondrial superoxide production and mRNA levels of pro-inflammatory cytokines and of inflammasome-components interleukin-1ß, NLRP3 and ASC. Protein levels of cleaved caspase-1 increased in CH-exposed hepatocytes. CM and EVs from hypoxic fat-laden hepatic cells evoked a pro-inflammatory phenotype in KC. Livers from CDAA-fed mice exposed to IH exhibited increased mRNA levels of pro-inflammatory and inflammasome genes and increased levels of cleaved caspase-1. CONCLUSION: Hypoxia promotes inflammatory signals including inflammasome/caspase-1 activation in fat-laden hepatocytes and contributes to cellular crosstalk with KC by release of EVs. These mechanisms may underlie the aggravating effect of OSAS on NAFLD. [Abstract word count: 257].

Assuntos

Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Hipóxia/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Hepatopatia Gordurosa não Alcoólica/genética , Apneia Obstrutiva do Sono/genética , Animais , Caspase 1/genética , Deficiência de Colina/genética , Deficiência de Colina/metabolismo , Deficiência de Colina/patologia , Cobalto/toxicidade , Modelos Animais de Doenças , Vesículas Extracelulares/genética , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/patologia , Ácidos Graxos não Esterificados/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Hipóxia/induzido quimicamente , Hipóxia/metabolismo , Hipóxia/patologia , Inflamassomos/genética , Inflamação/induzido quimicamente , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Interleucina-1beta/genética , Células de Kupffer/metabolismo , Células de Kupffer/patologia , Camundongos , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/patologia , Ratos , Apneia Obstrutiva do Sono/etiologia , Apneia Obstrutiva do Sono/metabolismo , Apneia Obstrutiva do Sono/patologia , Triglicerídeos/genética