RESUMO
The antioxidant effect of caffeine, associated with its ability to upregulate the nuclear factor-E2-related factor-2 (Nrf2)-signaling pathway, was explored as a possible mechanism for the attenuation of liver damage. Nonalcoholic steatohepatitis (NASH) was induced in rats by the administration of a high-fat, high-sucrose, high-cholesterol diet (HFSCD) for 15 weeks. Liver damage was induced in rats by intraperitoneal administration of thioacetamide (TAA) for six weeks. Caffeine was administered orally at a daily dose of 50 mg/kg body weight during the period of NASH induction to evaluate its ability to prevent disease development. Meanwhile, rats received TAA for three weeks, after which 50 mg/kg caffeine was administered daily for three weeks with TAA to evaluate its capacity to interfere with the progression of hepatic injury. HFSCD administration induced hepatic steatosis, decreased Nrf2 levels, increased oxidative stress, induced the activation of nuclear factor-κB (NF-κB), and elevated proinflammatory cytokine levels, leading to hepatic damage. TAA administration produced similar effects, excluding steatosis. Caffeine increased Nrf2 levels; attenuated oxidative stress markers, including malondialdehyde and 4-hydroxynonenal; restored normal, reduced glutathione levels; and reduced NF-κB activation, inflammatory cytokine levels, and damage. Our findings suggest that caffeine may be useful in the treatment of human liver diseases.
Assuntos
Antioxidantes , Hepatopatia Gordurosa não Alcoólica , Humanos , Ratos , Masculino , Animais , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Antioxidantes/metabolismo , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Tioacetamida/toxicidade , Cafeína/farmacologia , Cafeína/uso terapêutico , NF-kappa B/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Fígado , Estresse Oxidativo , Citocinas/metabolismo , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêuticoRESUMO
INTRODUCTION AND OBJECTIVES: Administration of carbon tetrachloride (CCl4), along with an hepatopathogenic diet, is widely employed as a chemical inducer to replicate human nonalcoholic steatohepatitis (NASH) in rodents; however, the role of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome in this model remains unclear. We aimed to determine the relevance of NLRP3 inflammasome activation in the development of NASH induced by CCl4 along with an hepatopathogenic diet in male Wistar rats. MATERIALS AND METHODS: Animals were fed either a high fat, sucrose, and cholesterol diet (HFSCD) or a HFSCD plus intraperitoneal injections of low doses of CCl4 (400 mg/kg) once a week for 15 weeks. Liver steatosis, inflammation, fibrosis, and NLRP3 inflammasome activation were evaluated using biochemical, histological, ultrastructural, and immunofluorescence analyses, western blotting, and immunohistochemistry. RESULTS: Our experimental model reproduced several aspects of the human NASH pathophysiology. NLRP3 inflammasome activation was induced by the combined effect of HFSCD plus CCl4 and significantly increased levels of both proinflammatory and profibrogenic cytokines and collagen deposition in the liver; thus, NASH severity was higher in the HFSCD+CCl4 group than that in the HFSCD group, to which CCl4 was not administered. Hepatic stellate cells, the most profibrogenic cells, were activated by HFSCD plus CCl4, as indicated by elevated levels of α-smooth muscle actin. Thus, activation of the NLRP3 inflammasome, triggered by low doses of CCl4, exacerbates the severity of NASH. CONCLUSIONS: Our results indicate that NLRP3 inflammasome activation plays a key role and may be an important therapeutic target for NASH treatment.
Assuntos
Hepatopatia Gordurosa não Alcoólica , Humanos , Ratos , Animais , Masculino , Camundongos , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Inflamassomos/efeitos adversos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Ratos Wistar , Fígado/patologia , Colesterol , Dieta Hiperlipídica/efeitos adversos , Camundongos Endogâmicos C57BLRESUMO
Caffeine elicits protective effects against liver diseases, such as NASH; however, its mechanism of action involving the pyrin domain-containing-3 (NLRP3) inflammasome signaling pathway remains to be elucidated. This study aimed to evaluate the effect of caffeine on the NLRP3 inflammasome signaling pathway in a rat model of NASH. NASH was induced by feeding rats a high-fat, -sucrose, and -cholesterol diet (HFSCD) for 15 weeks along with a weekly low dose (400 mg/kg, i.p.) of CCl4. Caffeine was administered at 50 mg/kg p.o. The effects of HFSCD+CCl4 and caffeine on the liver were evaluated using biochemical, ultrastructural, histological, and molecular biological approaches. The HFSCD+CCl4-treated rats showed fat accumulation in the liver, elevated levels of inflammatory mediators, NLRP3 inflammasome activation, antioxidant dysregulation, and liver fibrosis. Caffeine reduced necrosis, cholestasis, oxidative stress, and fibrosis. Caffeine exhibited anti-inflammatory effects by attenuating NLRP3 inflammasome activation. Moreover, caffeine prevented increases in toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) protein levels and mitigated the phosphorylation of mitogen-activated protein kinase (MAPK). Importantly, caffeine prevented the activation of hepatic stellate cells. This study is the first to report that caffeine ameliorates NASH by inhibiting NLRP3 inflammasome activation through the suppression of the TLR4/MAPK/NF-κB signaling pathway.
Assuntos
NF-kappa B , Hepatopatia Gordurosa não Alcoólica , Animais , Cafeína/farmacologia , Cafeína/uso terapêutico , Inflamassomos/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , Ratos , Transdução de Sinais , Receptor 4 Toll-Like/metabolismoRESUMO
INTRODUCTION AND OBJECTIVES: Caffeine consumption is associated with beneficial effects on hepatic disorders. The objectives of this study were to evaluate the antifibrotic effects of caffeine on experimental nonalcoholic steatohepatitis (NASH) induced with a high-fat, high-sucrose, high-cholesterol diet (HFSCD), as well as to evaluate the ability of caffeine to prevent the progression of experimental liver fibrosis induced by the administration of thioacetamide (TAA) in rats and explore the mechanisms of action. METHODS: NASH and fibrosis were induced in rats by the administration of an HFSCD for 15 weeks, and liver fibrosis was induced by intraperitoneal administration of 200 mg/kg TAA 3 times per week, for 6 weeks. Caffeine was administered at a dose of 50 mg/kg body weight. The effects of diet, TAA, and caffeine on fibrosis were evaluated by biochemical and histological examinations. The profibrotic pathways were analyzed by western blotting and immunohistochemistry. RESULTS: Rats exhibited liver fibrosis after HFSCD feeding and the administration of TAA. Caffeine could reduce the hepatic level of collagen and the fibrotic area in the liver. Caffeine prevented the progression of liver fibrosis by decreasing transforming growth factor-beta (TGF-ß), connective tissue growth factor (CTGF), and alpha-smooth muscle actin (α-SMA) expression and by inhibiting the activation of mitogen-activated protein kinases (MAPKs) and Smad3 phosphorylation. CONCLUSIONS: Caffeine attenuates NASH and the progression of liver fibrosis due to its antifibrotic effects and modulating the MAPK and TGF-ß pathways. Therefore, caffeine could be a suitable candidate for treating liver diseases associated with fibrosis.