Implicações e efeitos da utilização do inibidor da DPP-4 e ativação do ppar-alfa, isolados ou em associação, sobre o eixo entero-hepático de camundongos alimentados com dieta rica em frutose ou lipídeos

Abstract

High-fat and high-fructose diets are potent triggers of non-alcoholic fatty liver disease, intensified by gut-liver axis impairments. This study aimed to evaluate the effects of DPP-4 inhibitor activation and PPAR-α (WY14643) activation, alone or in combination, on the enterohepatic axis, inflammation and hepatic energy metabolism of mice fed a high-fat or high-fat diet fructose. Male C57BL/6 mice (3 months old) were fed a control diet (C, 10% of energy from lipid, n = 20), high-fat diet (HF, 50% of energy from lipid, n = 40) or high-fructose diet (HFRU, 50% of energy from fructose, n=40) for 12 weeks. After 12 weeks, the HF and HFRU groups were subdivided to receive treatment for 5 weeks (n = 10 per group): HF, HFA (PPAR-α agonist, 3.5 mg/kg/MC incorporated into the HF diet) , HFT (Linagliptin – Trayenta – 15mg/kg incorporated into the HF diet) and HFC (PPAR-α agonist associated with Linagliptin incorporated in the same doses to the HF diet); HFRU, HFRUA (PPAR-α agonist, 3.5 mg / kg /MC incorporated into the HFRU diet), HFRUT (Linagliptin 15mg/kg incorporated into the HFRU diet) and HFRUC (PPAR-α agonist associated with Linagliptin at the same doses incorporated into the HFRU diet). Biochemical analysis, RT-qPCR, immunofluorescence, and transmission electron microscopy (TEM) were performed in liver and intestine samples. The HFRU group presented glucose intolerance, endotoxemia and dysbiosis (with increased Proteobacteria) with no changes in body mass compared to the C group, but with intestinal ultrastructure damage, which led to liver inflammation and marked hepatic steatosis in the HFRU group compared to group C. The treatments rescued glucose intolerance, endotoxemia and dysbiosis, improving the ultrastructure of the intestinal barrier and reducing Tlr4 expression in the liver of treated animals. These beneficial effects suppressed lipogenesis and attenuated steatosis. The HF diet was obesogenic compared to the C diet. All treatments caused significant body mass loss, and the HFC group showed similar body mass to the C group. All treatments mitigated oral glucose intolerance and increased GLP1 levels. These metabolic benefits restored the Bacteroidetes/Firmicutes ratio, resulting in increased goblet cells per large intestine area and reduced LPS levels in the treated groups, which also showed higher Mucin 2, Occludin and Zo-1 expression compared to the HF group. Reduced endotoxemia suppressed gene expression of inflammasomes and macrophages in the liver of treated animals. These observations complied with a marked reduction in the volume density of steatosis and hepatic triacylglycerol, reaffirming the role of the proposed treatment in the mitigation of non-alcoholic fatty liver disease (NAFLD). Both treatments improved insulin resistance and maximized hepatic energy metabolism, favoring beta-oxidation, and controlling gut dysbiosis. However, the combined treatments showed the most expressive results in reversing the deleterious effects of high-fat and high-fructose diets. The activation of PPAR-α and inhibition of DPP-4 may be an approach to prevent the progression of NAFLD and other obesity comorbidities.