NLRP3 inflammasome blockade reduces liver inflammation and fibrosis in experimental NASH in mice.

NOD-like receptor protein 3 (NLRP3) inflammasome activation occurs in Non-alcoholic fatty liver disease (NAFLD). We used the first small molecule NLRP3 inhibitor, MCC950, to test whether inflammasome blockade alters inflammatory recruitment and liver fibrosis in two murine models of steatohepatitis. We fed foz/foz and wild-type mice an atherogenic diet for 16weeks, gavaged MCC950 or vehicle until 24weeks, then determined NAFLD phenotype. In mice fed an methionine/choline deficient (MCD) diet, we gavaged MCC950 or vehicle for 6weeks and determined the effects on liver fibrosis. In vehicle-treated foz/foz mice, hepatic expression of NLRP3, pro-IL-1β, active caspase-1 and IL-1β increased at 24weeks, in association with cholesterol crystal formation and NASH pathology; plasma IL-1β, IL-6, MCP-1, ALT/AST all increased. MCC950 treatment normalized hepatic caspase 1 and IL-1β expression, plasma IL-1β, MCP-1 and IL-6, lowered ALT/AST, and reduced the severity of liver inflammation including designation as NASH pathology, and liver fibrosis. In vitro, cholesterol crystals activated Kupffer cells and macrophages to release IL-1β; MCC950 abolished this, and the associated neutrophil migration. MCD diet-fed mice developed fibrotic steatohepatitis; MCC950 suppressed the increase in hepatic caspase 1 and IL-1β, lowered numbers of macrophages and neutrophils in the liver, and improved liver fibrosis. MCC950, an NLRP3 selective inhibitor, improved NAFLD pathology and fibrosis in obese diabetic mice. This is potentially attributable to the blockade of cholesterol crystal-mediated NLRP3 activation in myeloid cells. MCC950 reduced liver fibrosis in MCD-fed mice. Targeting NLRP3 is a logical direction in pharmacotherapy of NASH. Fatty liver disease caused by being overweight with diabetes and a high risk of heart attack, termed non-alcoholic steatohepatitis (NASH), is the most common serious liver disease with no current treatment. There could be several causes of inflammation in NASH, but activation of a protein scaffold within cells termed the inflammasome (NLRP3) has been suggested to play a role. Here we show that cholesterol crystals could be one pathway to activate the inflammasome in NASH. We used a drug called MCC950, which has already been shown to block NLRP3 activation, in an attempt to reduce liver injury in NASH. This drug partly reversed liver inflammation, particularly in obese diabetic mice that most closely resembles the human context of NASH. In addition, such dampening of liver inflammation in NASH achieved with MCC950 partly reversed liver scarring, the process that links NASH to the development of cirrhosis.

Mridha AR ，Wree A ，Robertson AAB ，Yeh MM ，Johnson CD ，Van Rooyen DM ，Haczeyni F ，Teoh NC ，Savard C ，Ioannou GN ，Masters SL ，Schroder K ，Cooper MA ，Feldstein AE ，Farrell GC ... -  《-》

The selective NLRP3 inflammasome inhibitor MCC950 alleviates cholestatic liver injury and fibrosis in mice.

Cholestasis occurs in many clinical circumstances and leads to severe liver disorders. MCC950, a small-molecule NLRP3 inhibitor, was previously shown to have anti-inflammatory effects. However, these effects have not yet been examined in cholestatic liver injury. This study aimed to investigate the role of NLRP3 inflammasome and test the therapeutic efficacy and molecular mechanisms of MCC950 in cholestatic liver injury through the common bile duct ligation (BDL) model in mice. The influence of MCC950 on histological changes, levels of liver damage, neutrophil infiltration, liver cell death, inflammatory cytokine levels, and NLRP3 inflammasome expression were examined. The results of the current study confirmed that NLRP3 components were up-regulated during bile duct obstruction. MCC950 treatment significantly alleviated BDL-induced liver injury by reducing production of the pro-inflammatory cytokines IL-1β and IL-18 and inhibiting neutrophil infiltration and hepatic cell death. Moreover, MCC950 significantly inhibited NLRP3 activation during cholestatic liver injury. In addition, transcriptome analysis indicated that Toll-like receptor signaling may be involved in the protective effects of MCC950 in cholestatic liver injury. In conclusion, experimental findings demonstrate that MCC950 exerted protective effects in cholestatic liver injury and liver fibrosis by blocking NLRP3 inflammasome activation and the mechanism was partially attributed to inhibition of Toll-like receptor signaling. The present study indicates MCC950 could potentially be an effective therapeutic strategy for the treatment of cholestatic liver injury.

Qu J ，Yuan Z ，Wang G ，Wang X ，Li K ... -  《-》

Benzyl isothiocyanate ameliorates high-fat/cholesterol/cholic acid diet-induced nonalcoholic steatohepatitis through inhibiting cholesterol crystal-activated NLRP3 inflammasome in Kupffer cells.

Incidence of nonalcoholic fatty liver disease is increasing worldwide. Activation of the NLRP3 inflammasome is central to the development of diet-induced nonalcoholic steatohepatitis (NASH). We investigated whether benzyl isothiocyanate (BITC) ameliorates diet-induced NASH and the mechanisms involved. C57BL/6 J mice fed a high-fat diet containing cholesterol and cholic acid (HFCCD) and Kupffer cells stimulated with LPS and cholesterol crystals (CC) were studied. LPS/CC increased the expression of the active form of caspase 1 (p20) and the secretion of IL-1β by Kupffer cells, and these changes were reversed by MCC950, an NLRP3 inflammasome inhibitor. LPS/CC-induced NLRP3 inflammasome activation and IL-1β production were dose-dependently attenuated by BITC. BITC decreased cathepsin B release from lysosomes and binding to NLRP3 induced by LPS/CC. Compared with a normal diet, the HFCCD increased serum levels of ALT, AST, total cholesterol, and IL-1β and hepatic contents of triglycerides and total cholesterol. BITC administration (0.1% in diet) reversed the increase in AST and hepatic triglycerides in the HFCCD group. Moreover, BITC suppressed lipid accumulation, macrophage infiltration, fibrosis, crown-like structure formation, and p20 caspase 1 and p17 IL-1β expression in liver in the HFCCD group. These results suggest that BITC ameliorates HFCCD-induced steatohepatitis by inhibiting the activation of NLRP3 inflammasome in Kupffer cells and may protect against diet-induced NASH.

Chen HW ，Yen CC ，Kuo LL ，Lo CW ，Huang CS ，Chen CC ，Lii CK ... -  《-》

The selective NLRP3-inflammasome inhibitor MCC950 reduces myocardial fibrosis and improves cardiac remodeling in a mouse model of myocardial infarction.

Early inflammatory responses after myocardial infarction (MI) are likely to increase myocardial fibrosis and subsequent cardiac remodeling. MCC950, a specific NLRP3 inhibitor, was previously found to effectively inhibit the release of inflammatory factors IL-18 and IL-1β. In this study, we evaluated the effect of MCC950, as a potential new treatment strategy for MI, on myocardial fibrosis and cardiac remodeling using an experimental mouse model. Male C57BL/6 mice were subjected to left coronary artery ligation to induce MI and then treated with MCC950 (10 mg/kg) or PBS for 14 days. After 30 days, echocardiography was performed to assess cardiac function and myocardial fibrosis was evaluated using H&E- and Masson's Trichrome-stained sections. Myocardial expression of inflammatory factors and fibrosis markers was analyzed by western blotting, immunofluorescence, ELISA, and real-time quantitative PCR. The ejection fraction in the 10 mg/kg group (40.7 ± 4.2%; N = 6, p = 0.0029) was statistically preserved compared to that in the control group (14.0 ± 4.4%). Myocardial fibrosis was also reduced in MCC950-treated animals (MCC950, 23.2 ± 3.0 vs PBS, 36.2 ± 3.7; p < 0.05). Moreover, myocardial NLRP3, cleaved IL-1β, and IL-18 levels were reduced in MCC950-treated animals. H&E and molecular examination revealed decreases in inflammatory cell infiltration and inflammatory factor expression in the heart. In vitro, MCC950 inhibited NLRP3, reduced caspase-1 activity, and further downregulated IL-1β and IL-18. MCC950, as a specific NLRP3 inhibitor, can alleviate fibrosis and improve cardiac function in a mouse model by suppressing early inflammatory responses post-MI.

Gao R ，Shi H ，Chang S ，Gao Y ，Li X ，Lv C ，Yang H ，Xiang H ，Yang J ，Xu L ，Tang Y ... -  《-》

Sweroside Prevents Non-Alcoholic Steatohepatitis by Suppressing Activation of the NLRP3 Inflammasome.

Yang G ，Jang JH ，Kim SW ，Han SH ，Ma KH ，Jang JK ，Kang HC ，Cho YY ，Lee HS ，Lee JY ... -  《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》