Serum Microcystin-LR Levels Linked with Risk of Inflammatory Bowel Disease: A Matched Case-Control Study in China

Microcystin-LR (MC-LR), the most prevalent and diverse cyanotoxin produced by harmful cyanobacterial blooms, has been linked to gastrointestinal toxicity. Therefore, we conducted a case-control study across four regions in China to investigate this relationship. Inflammatory bowel disease (IBD) cases (219) were matched with healthy controls (438) based on age and gender and conditional logistic regression models and Restricted cubic splines were used to evaluate the association between MC-LR exposure and IBD risk. We used quantitative real-time polymerase chain reaction to measure the expression levels of inflammatory factors. The levels of protein expression in the colorectum were determined using Western blotting (WB). Compared to the lowest quartile of serum MC-LR levels, the adjusted odds ratios and 95% confidence intervals (CI) for the highest quartiles of serum MC-LR levels were 5.51 (2.70, 11.21). The RCS was shown the association between serum MC-LR levels and IBD risk was nonlinear (P _nonlinear < 0.001). In the animal experiments, MC-LR resulted in colorectal injury via the PI3K/AKT signaling pathway. Our study provides the evidence that serum MC-LR exposure is significantly associated with the risk of IBD in China. Animal study results indicate that MC-LR probably causes IBD via the PI3K/AKT signaling pathway.