Celiac Disease Increases the Risk of Multiple Sclerosis: Evidence from Mendelian Randomization and the Role of CCL19.

Celiac disease (CeD) is an autoimmune disorder triggered by gluten, primarily affecting the small intestine but potentially impacting other systems, including the nervous system through the gut-brain axis. This study employed Mendelian randomization (MR) to explore the causal relationships between CeD and several neurological disorders, with a particular focus on multiple sclerosis (MS). Utilizing genetic data from the OpenGWAS and Finngen databases, we applied various MR methods, including Inverse Variance Weighted (IVW), IVW-multiplicative random effects (MRE), weighted median (WM), MR-Egger, and robust adjusted profile score (RAPS), to investigate these associations. The analysis revealed no significant causal relationship between CeD and several other neurological disorders, but a significant positive association with MS was found (IVW OR=1.1919, 95% CI: 1.0851~1.3092, p=0.0002). Further analysis indicated that the mediator CCL19 plays a significant role in the pathway from CeD to MS, suggesting that CCL19 may be a key factor in the immune response linking these conditions. This mediation effect highlights the potential mechanism through which CeD increases the risk of developing MS. These findings emphasize the complexity of the relationship between CeD and MS, indicating the need for further research to understand these connections better and their clinical implications.