Alcohol-induced liver disease (ALD) is a complex disorder, with a disease spectrum ranging from steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Although the pathogenesis of ALD is incompletely understood and currently no effective drugs are available for ALD, several lines of evidence suggest that complement activation and oxidative stress play crucial roles in the pathogenesis of ALD. Complement activation can regulate the production of ROS and influence oxidative stress in ALD. Precise regulation of the complement system in ALD may be a rational and novel avenue to postpone and even reverse the progression of disease and simultaneously promote the repair of liver injury. In this mini-review, we briefly summarize the recent research progress, especially focusing on the role of complement and oxidative stress-induced transfer RNA-derived fragments, which might help us to better understand the pathogenesis of ALD and provide aid in the development of novel therapeutic strategies for ALD.

Background/Aims: To evaluate the causal correlation between complement components and non-viral liver diseases and their potential use as druggable targets. Methods: We conducted Mendelian randomization (MR) to assess the causal role of circulating complements in the risk of non-viral liver diseases. A complement-centric protein interaction network was constructed to explore biological functions and identify potential therapeutic options. Results: In the MR analysis, genetically predicted levels of complement C1q C chain (C1QC) were positively associated with the risk of autoimmune hepatitis (odds ratio 1.125, 95% confidence interval 1.018–1.244), while complement factor H-related protein 5 (CFHR5) was positively associated with the risk of primary sclerosing cholangitis (PSC;1.193, 1.048– 1.357). On the other hand, CFHR1 (0.621, 0.497–0.776) and CFHR2 (0.824, 0.703–0.965) were inversely associated with the risk of alcohol-related cirrhosis. There were also significant inverse associations between C8 gamma chain (C8G) and PSC (0.832, 0.707–0.979), as well as the risk of metabolic dysfunction-associated steatotic liver disease (1.167, 1.036–1.314). Additionally, C1S (0.111, 0.018–0.672), C7 (1.631, 1.190–2.236), and CFHR2 (1.279, 1.059–1.546) were significantly associated with the risk of hepatocellular carcinoma. Proteins from the complement regulatory networks and various liver diseaserelated proteins share common biological processes. Furthermore, potential therapeutic drugs for various liver diseases were identified through drug repurposing based on the complement regulatory network. Conclusions Our study suggests that certain complement components, including C1S, C1QC, CFHR1, CFHR2, CFHR5, C7, and C8G, might play a role in non-viral liver diseases and could be potential targets for drug development.