Causal relationships between plasma metabolites and prostate cancer: A Mendelian randomization study exploring immune and inflammatory mediators

Abstract Background Metabolic alterations and inflammatory processes contribute substantially to the pathogenesis of prostate cancer (PCa). This study used Mendelian randomization (MR) to investigate the causal relationships between plasma metabolites and PCa and to identify potential mediators, including immune cell traits and circulating inflammatory proteins. Materials and methods A 2-sample MR analysis was conducted using data from the Canadian Longitudinal Study on Aging and a diverse genome-wide association study of PCa. A total of 1400 plasma metabolites were analyzed. Single-nucleotide polymorphisms were carefully selected and refined using linkage disequilibrium clumping. The inverse variance weighting method was used for primary analysis, supplemented by sensitivity analyses, including MR-Egger, weighted median, and MR-Pleiotropy RESidual Sum and Outlier, to ensure the robustness of the results. Results Eight metabolites were significantly associated with PCa. Specifically, a higher phosphate-to-uridine ratio was associated with a decreased risk of PCa, whereas higher levels of N -acetyl-arginine were linked to an increased risk. Other significant metabolites included the phosphate-to-2′-deoxyuridine ratio; N6-methyl-lysine, N -acetyl-leucine, N -succinyl-phenylalanine, and cysteinylglycine disulfide levels; and the α-ketoglutarate-to-ornithine ratio. Sensitivity analyses and the MR–Steiger test confirmed the robustness and causal direction of these associations. In addition, further analysis indicated that certain metabolites may influence PCa risk by modulating the expression of inflammatory markers, such as leukemia inhibitory factor receptor, interleukin-8, and CD33-related markers. Conclusions This study identified plasma metabolites that exert causal effects on the risk of PCa and highlighted the mediating role of immune traits and inflammatory proteins. These findings underscore the complexity of the biological pathways involved and suggest potential targets for therapeutic interventions.