IL-1 receptor antagonist ameliorates inflammasome-dependent alcoholic steatohepatitis in mice

Alcoholic liver disease (ALD) is characterized by steatosis and upregulation of proinflammatory cytokines, including IL-1beta. IL-1beta, type I IL-1 receptor (IL-1R1), and IL-1 receptor antagonist (IL-1Ra) are all important regulators of the IL-1 signaling complex, which plays a role in inflammation. Furthermore, IL-1beta maturation is dependent on caspase-1 (Casp-1). Using IL-1Ra-treated mice as well as 3 mouse models deficient in regulators of IL-1beta activation (Casp-1 and ASC) or signaling (IL-1R1), we found that IL-1beta signaling is required for the development of alcohol-induced liver steatosis, inflammation, and injury. Increased IL-1beta was due to upregulation of Casp-1 activity and inflammasome activation. The pathogenic role of IL-1 signaling in ALD was attributable to the activation of the inflammasome in BM-derived Kupffer cells. Importantly, in vivo intervention with a recombinant IL-1Ra blocked IL-1 signaling and markedly attenuated alcohol-induced liver inflammation, steatosis, and damage. Furthermore, physiological doses of IL-1beta induced steatosis, increased the inflammatory and prosteatotic chemokine MCP-1 in hepatocytes, and augmented TLR4-dependent upregulation of inflammatory signaling in macrophages. In conclusion, we demonstrated that Casp-1-dependent upregulation of IL-1beta and signaling mediated by IL-1R1 are crucial in ALD pathogenesis. Our findings suggest a potential role of IL-1R1 inhibition in the treatment of ALD

Caspase-1-dependent, IL-1ß-mediated alcoholic steatohepatitis is ameliorated by IL-1 receptor antagonist treatment in mice

Alcoholic liver disease (ALD) is characterized by steatosis and upregulation of pro-inflammatory cytokines, including interleukin (IL)-1β. IL-1β, Type-I IL-1 receptor (IL1R1) and IL-1 receptor antagonist (IL-1Ra) are all part of the IL-1 superfamily that play a role in inflammation. IL-1β maturation is dependent on Caspase-1. Using wild-type (WT), Caspase-1-, IL-1R1- and IL-1Ra deficient mice fed with Lieber-DeCarli alcohol or control diet, we have identified that signaling mediated by the active IL-1β was required for development of alcohol-induced steatosis, inflammation and injury. Increased IL-1β was due to upregulation of Caspase-1 activity and inflammatory activation. The pathogenic role of IL-1 signaling in ALD was attributable to the presence of IL-1R1 on liver parenchymal cells. Importantly, in vivo intervention with recombinant IL-1Ra, Anakinra, which blocks IL-1 signaling, significantly attenuated both liver steatosis and inflammation. In primary hepatocytes, physiological doses of IL-1β induced steatosis and upregulated the inflammatory and pro-steatotic chemokine MCP-1. MCP-1, but not IL-1β induced hepatocyte cytotoxicity at concentrations found in ALD. In conclusion, we demonstrate that Caspase-1-dependent upregulation of IL-1β and signaling mediated by IL-1 is crucial in the pathogenesis of ALD in a cell specific manner. Our findings suggest a potential role of IL-1Ra in the treatment of ALD