Exploring the Effect of the Gut Microbiome on the Risk of Age-Related Macular Degeneration From the Perspective of Causality

To explore the mechanisms relating the gut microbiome (GM) to age-related macular degeneration (AMD), as they remain unclear. GM taxa that appear to act within the gut-retina axis may affect the risk of AMD. Single-nucleotide polymorphisms (SNPs) of 196 GM taxa were obtained from the MiBioGen consortium, and a Mendelian randomization (MR) study was carried out to estimate the causality between GM taxa and AMD (defined as an endpoint based on ICD-9 and ICD-10). Using the data from the FinnGen consortium (6157 patients and 288,237 controls), we explored the GM taxa for causality and verified the results at the replication stage based on the MRC-IEU consortium (3553 cases and 147,089 controls). Inverse variance weighting (IVW) was the main method used to analyze causality, and the MR results were verified using heterogeneity tests and pleiotropy tests. According to the MR results, order Rhodospirillales (P = 3.38 × 10-2), family Victivallaceae (P = 3.14 × 10-2), family Rikenellaceae (P = 3.58 × 10-2), genus Slackia (P = 3.15 × 10-2), genus Faecalibacterium (P = 3.01 × 10-2), genus Bilophila (P = 1.11 × 10-2), and genus Candidatus Soleaferrea (P = 2.45 × 10-2) were suggestively associated with AMD. In the replication stage, only order Rhodospirillales (P = 0.03) passed validation. The heterogeneity (P > 0.05) and pleiotropy (P > 0.05) tests in two stages confirmed the robustness of the MR results. We confirmed that order Rhodospirillales influenced the risk of AMD based on the gut-retina axis, providing new impetus for the development of the GM as an intervention to prevent the occurrence and development of AMD.