Genetically predicted serum ferritin mediates the association between inflammatory cytokines and non-alcoholic fatty liver disease.

Objective: Investigating the causal relationship between inflammatory cytokines and Non-alcoholic fatty liver disease(NAFLD) and identifying and quantifying the role of serum ferritin as a potential mediator.

Methods: Genetic summary statistics were derived from open genome-wide association study (GWAS) databases. We conducted a two-sample Mendelian randomization (MR) analysis to investigate the relationship between inflammatory cytokines (8,293 individuals) and NAFLD (8,434 cases, 770,180 controls). Furthermore, we used two-step MR to quantitate the proportion of the effect of serum ferritin-mediated inflammatory cytokines on NAFLD. In this study, we primarily utilized inverse-variance-weighted Mendelian randomization (MR-IVW) and reverse MR analysis methods, while other methods were also performed for sensitivity analysis, false discovery rate (FDR) <0.0012 as statistical significance in MR analyses.

Results: Our results indicated that high levels of Eotaxin, regulated upon activation normal T cell expressed and presumably secreted(RANTES), Interleukin-2(IL-2), macrophage migration inhibitory factor(MIF), tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) and Stem cell factor(SCF) were associated with increased risks of NAFLD, while high Cutaneous T cell-attracting chemokine(CTACK) and Interleukin-16(IL-16) levels that reduced the risk of NAFLD.The proportion of genetically predicted NAFLD mediated by ferritin was 2.1%(95% CI = 1.39%-5.61%).

Conclusion: In conclusion, our study identified a causal relationship between inflammatory cytokines and NAFLD, with a small proportion of the effect mediated by ferritin, but a majority of the effect of inflammatory cytokines on NAFLD remains unclear. Further research is needed on additional risk factors as potential mediators.