Benzyl isothiocyanate attenuates activation of the NLRP3 inflammasome in Kupffer cells and improves diet-induced steatohepatitis.

The NLRP3 inflammasome plays an important role in the pathogenesis of numerous inflammation-related diseases. Benzyl isothiocyanate (BITC) is rich in cruciferous vegetables and possesses potent antioxidant, anti-inflammatory, anti-cancer, and anti-obesogenic properties. In this study, we investigated the role of the NLRP3 inflammasome in the protection by BITC against steatohepatitis and insulin resistance. A mouse model of high-fat/cholesterol/cholic acid diet (HFCCD)-induced steatohepatitis, LPS/nigericin-stimulated primary Kupffer cells, and IL-1β treated primary hepatocytes were used. BITC attenuated LPS/nigericin-induced activation of the NLRP3 inflammasome by enhancing protein kinase A-dependent NLRP3 ubiquitination, which increased the degradation of NLRP3 and reduced IL-1β secretion in Kupffer cells. In hepatocytes, BITC pretreatment reversed the IL-1β-induced decrease in the phosphorylation of IR, AKT, and GSK3β in response to insulin. After 12 weeks of HFCCD feeding, increases in blood alanine aminotransferase (ALT) and glucose levels were ameliorated by BITC. Hepatic IL-1β production, macrophage infiltration, and collagen expression induced by HFCCD were also mitigated by BITC. BITC suppresses activation of the NLRP3 inflammasome in Kupffer cells by enhancing the PKA-dependent ubiquitination of NLRP3, which leads to suppression of IL-1β production and subsequently ameliorates hepatic inflammation and insulin resistance.