Molecular Profiling of the Appendix in Pediatric Inflammatory Bowel Diseases

Clinical studies suggest a critical role for the appendix in the pathogenesis of inflammatory bowel diseases (IBD), including Crohn disease (CD) and ulcerative colitis (UC), as indicated by the presence of peri-appendicular patches in UC and the beneficial effects of appendectomy in UC. However, the underlying mechanisms remain unclear. To address this gap, we characterized microbial species, associated patterns, and host-microbiota interactions in the appendix and non-inflamed regions of the colon tissue and mucus from pediatric IBD and non-IBD patients (n=15). Metagenomic analyses revealed an enrichment of Proteobacteria (p-value=0.0061) and reduced bacterial diversity in IBD patients’ appendix compared to controls. Strong correlations between host tissue and mucus microbial pathways of IBD patients highlighted a link between microbial communities and host gene expression, contributing to immune activation and inflammation in the appendix. Our findings thus provide valuable insights and a basis for mechanistic hypotheses regarding the appendix’s role in IBD pathogenesis.