The Gut Microbiome in Stevens–Johnson Syndrome and Sjögren’s Disease: Correlations with Dry Eye

Changes in gut microbial composition may influence mucosal immune responses and contribute to systemic autoimmune manifestations. In this pilot exploratory study, we investigated and compared the gut microbiome in patients with Stevens-Johnson syndrome (SJS), patients with Sjögren's disease (SjD), and healthy controls, using next-generation sequencing (NGS), and assessed correlations with dry eye parameters. The study included 10 patients with SJS matched by age and sex to 10 healthy controls, and 10 patients with SjD matched to an additional set of 10 healthy controls. Dry eye parameters were employed to evaluate dry eye disease (DED). Microbiome profiles were determined using next-generation sequencing of the 16S V3-V4 region and analyzed using the Silva database. The gut microbiome exhibited significant differences in the SJS group, including a reduced Chao1 index (<i>p</i> = 0.01) that was progressively correlated with increased ocular severity and a decrease in <i>Faecalibacterium</i> (<i>p</i> = 0.048) compared to the healthy control group. In the SJS group, strong correlations were observed between increased <i>Christensenellaceae</i> with decreased DED DEWS (Dry Eye Workshop score) (<i>p</i> = 0.04), increased <i>Subdoligranulum</i> with decreased NEI (National Eye Institute) score (<i>p</i> = 0.04), and increased <i>Clostridia</i> and longer TBUT (tear break-up time) (<i>p</i> = 0.009). In contrast, the gut microbiome of SjD patients was similar to that of healthy controls. Patients with SJS exhibited distinct alterations in gut microbial composition, characterized by reduced microbial richness and depletion of <i>Faecalibacterium</i>. Furthermore, a significant association was found between specific bacterial taxa and milder dry eye severity, suggesting a possible link between changes in the gut microbiome and inflammation of the ocular surface.