RESUMEN
Erectile dysfunction ranks among the prevalent sexual disorders in men. Several studies have indicated a potential link between gut microbiota and erectile dysfunction. To validate this potential association, we were to screen statistical data from genome-wide association studies of gut microbiota and erectile dysfunction. p values of less than 1 × 10-5 were set as the threshold for screening instrumental variables that were strongly associated with gut microbiota. At the same time, in order to obtain more convincing findings, we further excluded instrumental variables with possible chain imbalance, instrumental variables with the presence of palindromes, instrumental variables with F-statistics less than 10, and instrumental variables associated with risk factors for erectile dysfunction. Five methods including inverse-variance weighted method, weighted median method, weighted mode, Mendelian randomization egger method and Mendelian randomization pleiotropy residual sum and outlier test were then used to analyse the 2591 instrumental variables obtained from the screening. We identified correlations between six gut microbiota and the risk of erectile dysfunction. The genus Ruminococcaceae UCG-013 exhibited an inverse association with the risk of developing erectile dysfunction (0.79 (0.65-0.97), P = 0.0214). Conversely, the genus Tyzzerella3 (1.13 (1.02-1.26), P = 0.0225), genus Erysipelotrichaceae UCG-003 (1.18 (1.01-1.38), P = 0.0412), genus LachnospiraceaeNC2004group (1.19 (1.03-1.37), P = 0.0191), genus Oscillibacter (1.23 (1.08-1.41), P = 0.0022), and family Lachnospiraceae (1.26 (1.05-1.52), P = 0.0123) demonstrated positive associations with an increased risk of erectile dysfunction. These sensitivity analyses of the gut microbiota were consistent. This study demonstrated a possible causal relationship between gut microbiota and erectile dysfunction risk through Mendelian randomization analysis, providing new potential possibilities for the prevention and treatment of erectile dysfunction.
RESUMEN
Erectile dysfunction is a common sexual disorder in men. Some studies have found a strong association between some serum metabolites and erectile dysfunction. To investigate this association further, we used bidirectional Mendelian randomisation to investigate causality and possible biological mechanisms.Firstly, this study screened the statistics of genome-wide association studies of serum metabolites and erectile dysfunction to obtain instrumental variables. Inverse variance weighting was used as the primary method for causal effect analysis of instrumental variables in forward or reverse Mendelian randomisation, and the results obtained by MR-Egger regression and the weighted median method were used as references. Subsequently, the metabolites causally associated with erectile dysfunction were subjected to replication analyses and meta-analyses, and the results of the meta-analyses were analysed by pathway analyses to find influential pathways. In this process, Mendelian randomisation results need to be assessed for stability and reliability using sensitivity analysis.It was found that a total of six serum metabolites were causally associated with erectile dysfunction in a forward Mendelian randomisation study. 1,3,7-trimethyluraten (0.85 (0.73-0.99), P = 0.0368), ergothioneine (0.65 (0.45-0.94), P = 0.0226) and gamma-glutamylglutamate (0.63 (0.46-0.88), P = 0.0059) were protective against the development of erectile dysfunction, whereas 2-hydroxyhippurate (1.10 (1.02-1.19), P = 0.0152), N2,N2-dimethylguanosine (1.57 (1.02-2.40), P = 0.0395) and octanoylcarnitine (1.38 (1.06-1.82), P = 0.0183) were able to induce the development of erectile dysfunction. In addition, metabolic pathway analysis showed that 1,3,7-trimethylurate was able to influence the development of erectile dysfunction via the caffeine metabolism pathway (P = 0.0454). On the other hand, reverse Mendelian randomisation analysis showed that erectile dysfunction reduced serum homocitrulline levels (0.99 (0.97-1.00), P = 0.0360). Sensitivity analyses, including heterogeneity tests and pleiotropy tests, confirmed the reliability of the results.In conclusion, this study demonstrated a bidirectional causal relationship between serum metabolites and erectile dysfunction using bidirectional Mendelian randomisation analysis and replication meta-analysis. On this basis, this study provides a new direction of thinking and strong evidence for the therapeutic application and adjunctive diagnosis of serum metabolites in erectile dysfunction, and provides a certain reference value for subsequent related studies.