Ipragliflozin, a sodium-glucose cotransporter 2 inhibitor, ameliorates the development of liver fibrosis in diabetic Otsuka Long-Evans Tokushima fatty rats.

BACKGROUND: It is widely understood that insulin resistance (IR) critically correlates with the development of liver fibrosis in several types of chronic liver injuries. Several experiments have proved that anti-IR treatment can alleviate liver fibrosis. Sodium-glucose cotransporter 2 (SGLT2) inhibitors comprise a new class of antidiabetic agents that inhibit glucose reabsorption in the renal proximal tubules, improving IR. The aim of this study was to elucidate the effect of an SGLT2 inhibitor on the development of liver fibrosis using obese diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats and their littermate nondiabetic Long-Evans Tokushima Otsuka (LETO) rats. METHODS: Male OLETF and LETO rats were intraperitoneally injected with porcine serum twice a week for 12 weeks to augment liver fibrogenesis. Different concentrations of ipragliflozin (3 and 6 mg/kg) were orally administered during the experimental period. Serological and histological data were examined at the end of the experimental period. The direct effect of ipragliflozin on the proliferation of a human hepatic stellate cell (HSC) line, LX-2, was also evaluated in vitro. RESULTS: OLETF rats, but not LETO rats, received 12 weeks of porcine serum injection to induce severe fibrosis. Treatment with ipragliflozin markedly attenuated the development of liver fibrosis and expression of hepatic fibrosis markers, such as alpha smooth muscle actin, collagen 1A1, and transforming growth factor beta (TGF-ß), and improved IR in a dose-dependent manner in OLETF rats. In contrast, the proliferation of LX-2 in vitro was not affected, suggesting that ipragliflozin had no significant direct effect on the proliferation of HSCs. CONCLUSION: In conclusion, our dataset suggests that an SGLT2 inhibitor could alleviate the development of liver fibrosis by improving IR in naturally diabetic rats. This may provide the basis for creating new therapeutic strategies for chronic liver injuries with IR.

Beneficial effects of combined ursodeoxycholic acid and angiotensin-II type 1 receptor blocker on hepatic fibrogenesis in a rat model of nonalcoholic steatohepatitis.

BACKGROUND AND AIMS: Ursodeoxycholic acid (UDCA) is considered to be effective in the treatment of nonalcoholic steatohepatitis (NASH), particularly in combination with other pharmacological agents. UDCA reportedly counteracts the effects of endotoxemia. Previously, we demonstrated attenuated hepatic fibrogenesis and suppression of activated hepatic stellate cells (Ac-HSC) with an angiotensin-II (AT-II) type 1 receptor blocker (ARB). Here we evaluated the simultaneous effect of both agents on hepatic fibrogenesis in a rat model of NASH. METHODS: Fischer 344 rats were fed a choline-deficient L-amino-acid-defined (CDAA) diet for 8 weeks. The therapeutic effect of UDCA and ARB was evaluated along with hepatic fibrogenesis, lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4) regulatory cascade, and intestinal barrier function. The direct inhibitory effect of both UDCA and ARB on Ac-HSC was assessed in vitro. RESULTS: Both UDCA and ARB had a potent inhibitory effect on hepatic fibrogenesis with suppression of the HSC activation and hepatic expression of transforming growth factor (TGF)-ß1 and TLR4. UDCA decreased intestinal permeability by ameliorating zonula occuludens-1 (ZO-1) disruption induced by the CDAA diet. ARB was found to directly suppress regulation of Ac-HSC. CONCLUSIONS: UDCA and ARB have a synergistic repressive effect on hepatic fibrogenesis by counteracting endotoxemia induced by intestinal barrier dysfunction and suppressing the activation of Ac-HSC. Because both agents are currently used in clinical practice, combined UDCA and ARB may represent a promising novel therapeutic approach for NASH.

Reduction of endotoxin attenuates liver fibrosis through suppression of hepatic stellate cell activation and remission of intestinal permeability in a rat non-alcoholic steatohepatitis model.

Previous clinical studies have demonstrated that endotoxin/toll­like receptor 4 (TLR4) signaling is critical in the inflammatory pathways associated with non­alcoholic steatohepatitis (NASH). In human and animal studies, NASH was associated with portal lipopolysaccharide (LPS) and the plasma LPS level was hypothesized to be associated with small intestinal bacterial overgrowth, change in composition of the microbiota and increased intestinal permeability. The aim of the present study was to investigate the roles of endogenous endotoxin and TLR4 in the pathogenesis of NASH. The effects of antibiotics were assessed in vivo using a choline deficiency amino acid (CDAA)­induced experimental liver fibrosis model. Antibiotics, including polymyxins and neomycins, were orally administered in drinking water. Antibiotics attenuated hepatic stellate cell (HSC) activation and liver fibrosis via TGF­ß and collagen in an experimental hepatic fibrosis model. The mechanism by which antibiotics attenuated LPS­TLR4 signaling and liver fibrosis was assessed. Notably, TLR4 mRNA level in the liver was elevated in the CDAA group and the CDAA­induced increase was significantly reduced by antibiotics. However, no significant differences were observed in the intestine among all groups. Elevated mRNA levels of LPS binding protein, which was correlated with serum endotoxin levels, were recognized in the CDAA group and the CDAA­induced increase was significantly reduced by antibiotics. The intestinal permeability of the CDAA group was increased compared with the choline­supplemented amino acid group. The tight junction protein (TJP) in the intestine, determined by immunohistochemical analysis was inversely associated with intestinal permeability. Antibiotics improved the intestinal permeability and enhanced TJP expression. Inhibition of LPS­TLR4 signaling with antibiotics attenuated liver fibrosis development associated with NASH via the inhibition of HSC activation. These results indicated that reduction of LPS and restoration of intestinal TJP may be a novel therapeutic strategy for treatment of liver fibrosis development in NASH.