Modulation of interleukin-36 based inflammatory feedback loop through the hepatocyte-derived IL-36R-P2X7R axis improves steatosis in alcoholic steatohepatitis.

BACKGROUND AND PURPOSE: Interleukin-36 is induced by proinflammatory cytokines and promotes inflammatory responses, creating an IL-36-based inflammation loop. Although hepatocytes, produce IL-36 responses to drug-induced liver injury, little is known about the mechanistic role of IL-36 signalling during the progression of alcoholic steatohepatitis (ASH). Regarding IL-36/IL-36R and P2X7R coregulating the inflammatory response, we elucidated that modulation of IL-36R-P2X7R-TLR axis affected hepatocyte steatosis as well as the IL-36-based inflammatory feedback loop that accompanies the onset of ASH. EXPERIMENTAL APPROACH: C57BL/6J mice were subjected to either chronic-plus-binge ethanol feeding or acute gavage with multiple doses of ethanol to establish ASH, followed by pharmacological inhibition or genetic silencing of IL-36R and P2X7R. AML12 cells or mouse primary hepatocytes were stimulated with alcohol, LPS plus ATP or Poly(I:C) plus ATP, followed by silencing of IL-36γ, IL-36R or P2X7R. KEY RESULTS: P2X7R and IL-36R deficiency blocked the inflammatory loop, specifically initiated by IL-36 cytokines, in hepatocytes of mice suffering from ASH. Pharmacological inhibition to P2X7R or IL-36R alleviated lipid accumulation and inflammatory response in ASH. IL-36R was indispensable for P2X7R modulated NLRP3 inflammasome activation in ASH, and IL-36 led to a vicious cycle of P2X7R-driven inflammation in alcohol-treated hepatocytes. TLR ligands promoted IL-36γ production in hepatocytes, based on synergism with P2X7R. CONCLUSIONS AND IMPLICATIONS: Blockade of IL-36 based inflammatory feedback loop, via IL-36R-P2X7R-TLRs-modulated NLRP3 inflammasome activation, circumvented steatosis and inflammation that accompanies the onset of ASH, suggesting that targeting IL-36 can serve as a novel therapeutic approach to combat ASH.

The in vitro and in vivo study of a pyrazole derivative, J-1063, as a novel anti-liver fibrosis agent: Synthesis, biological evaluation, and mechanistic analysis.

In the present study, we completed the synthesis of a pyrazole derivative J-1063 and evaluated the kinase inhibitory activity of J-1063 activin receptor-like kinase 5 (ALK5) and p38α mitogen-activated protein (MAP) in the enzymatic assay. We evaluated anti-fibrotic effects of J-1063 on TGF-ß-induced hepatic stellate cells activation and TAA induced mice liver fibrosis. J-1063 showed much prior anti-fibrotic effects than those with LY2157299. Our data revealed that J-1063 exerted anti-fibrotic activity by inhibiting TGF-ßR1 (ALK5), which is likely related to the inhibition of TGF-ß--Smad signaling and NLRP3 inflammasome activation. The results suggest that J-1063 might be potential candidates for further anti-liver fibrosis drug development.

Inhibition of HMGB1/TLR4 Signaling Pathway by Digitoflavone: A Potential Therapeutic Role in Alcohol-Associated Liver Disease.

Digitoflavone (DG) is a natural flavonoid abundant in many fruits, vegetables, and medicinal plants. We investigated whether DG inhibits lipid accumulation and inflammatory responses in alcoholic liver disease (ALD) in vivo and in vitro. The mouse ALD model was established by chronically feeding male C57BL/6 mice an ethanol-containing Lieber-DeCarli liquid diet. In vitro, mouse peritoneal macrophages (MPMs) and mouse bone marrow-derived macrophages (BMDMs) were stimulated with LPS/ATP, whereas HepG2 cells and mouse primary hepatocytes were treated with ethanol. DG reduced the serum levels of transaminase and serum and hepatic levels of triglycerides and malondialdehyde in ALD mice. DG downregulated SREBP1 and its target genes and upregulated PPARα and its target genes in the liver of mice with ALD. DG inhibited TLR4-mediated NLRP3 inflammasome activation, consequently reversing the inflammatory response, including the production of HMGB1, IL-1ß, and IL-36γ, as well as the infiltration of macrophages and neutrophils. DG blocked NLRP3/ASC/caspase-1 inflammasome activation and HMGB1 release in LPS/ATP-stimulated MPMs. When Tlr4 was knocked in LPS/ATP-stimulated BMDMs, HMGB1 production and release were blocked, and NLRP3-mediated cleavage and release of IL-1ß was suppressed in Hmgb1-silenced BMDMs. DG amplified these inhibitory effects in Tlr4 or Hmgb1 knockdown BMDMs. In ethanol-exposed hepatocytes, DG reduced lipogenesis and promoted lipid oxidation by inhibiting the HMGB1-TLR4 signaling pathway while suppressing the inflammatory response induced by ethanol exposure. Our data demonstrated that DG inhibited the occurrence of lipid accumulation and the inflammatory response via the HMGB1-TLR4 axis, underscoring a promising approach and utility of DG for the treatment of ALD.