Distribution of IL-33 genetic variants and circulating IL-33 levels in patients with multiple sclerosis: associations with clinical parameters in a Lithuanian population study.

Interleukin-33 (IL-33) is an important regulator of immune and neuroinflammatory responses implicated in multiple sclerosis (MS), yet its genetic contribution to disease susceptibility remains unclear. In this study, we examined three IL-33 variants (rs1157505, rs7044343, rs11792633) and circulating IL-33 levels in a Lithuanian case-control cohort (280 MS patients and 280 controls). No statistically significant associations were observed in the overall genetic analysis. However, exploratory sex and age stratified analyses identified subgroup-specific associations, with rs1157505 associated with increased odds of MS in women and with clinical parameters, whereas rs7044343 and rs11792633 showed associations in men. Genetic associations were observed only in participants older than 38 years. Circulating IL-33 levels were lower in MS patients than in controls. Taken together, these findings suggest that IL-33 variants may be associated with selected MS related characteristics in this Lithuanian cohort; however, the subgroup findings should be interpreted cautiously and require replication in larger independent studies.