Exploring the role of inflammatory cytokines in obesity-mediated MASLD development and drug target identification

Numerous studies have confirmed the interconnections among obesity, inflammatory factors, and MASLD. However, the mediating role of inflammatory factors in the obesity-MASLD pathway remains unexplored in current research. We applied a two-step Mendelian randomization model to investigate whether inflammatory factors mediate the causal relationship between BMI and MASLD. A multivariable Mendelian randomization (MVMR) study was conducted for mediation analysis to quantify the proportion of mediation mediated by these factors. Genetic variations linked to drug target genes were identified from GWAS data for drug target analysis. Significant drug targets were further validated using relevant protein quantitative trait loci (pQTL) data. Co-localization and single-cell RNA sequencing were conducted to validate the robustness and feasibility of identified drug targets. The results revealed that only C-reactive protein (CRP) emerged as a risk factor for MASLD, mediating 14% of the association between BMI and MASLD. To explore therapeutic targets, we employed two types of genetic instruments to proxy drug target engagement: genetic variants within or near drug target genes and pQTL associated with drug targets. In two independent datasets, genetic proxies for enhanced APOE and GCKR activity were associated with increased MASLD risk. Blood APOE and GCKR protein levels demonstrated significant MR associations with MASLD and strong colocalization. Single-cell RNA sequencing revealed pronounced APOE expression in MASLD-affected liver tissue, particularly in Kupffer cells. This Mendelian randomization study provides novel genetic evidence supporting the CRP-mediated association between obesity and MASLD. Furthermore, APOE and GCKR inhibitors were identified as potential therapeutic targets for MASLD; however, the evidence supporting GCKR remains less robust and warrants further validation.