The Molecular Landscape of Inflammation in Inflammatory Bowel Disease (IBD): Targets for Precision Medicine

Abstract

Inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic immune-mediated disorders characterized by mucosal injury, cycles of inflammation and repair, and tissue damage. Persistent inflammation accelerates epithelial turnover, generates oxidative and replication stress, and remodels the stromal niche, contributing to the risk of colorectal cancer (CRC). Systematic dysplasia surveillance remains essential. Cellular senescence has emerged as a unifying mechanism linking inflammation, impaired epithelial repair, fibrosis, and neoplasia. In UC, p16/p21 upregulation, telomere erosion, and loss of lamin B1 accumulate and adopt a senescence-associated secretory phenotype (SASP) that perpetuates barrier dysfunction. In CD, senescence within stem and stromal compartments limits regeneration, promotes pro-fibrotic remodeling, and sustains cycles of injury and repair via chronic SASP signaling. IBD prevalence continues to rise from environmental factors, dietary changes, antibiotic exposures, and gut microbiota alterations. Pathogenesis integrates genetic factors (e.g., NOD2, IL23R, HLA, and ATG16L1 mutations), environmental modifiers, dysbiosis characterized by loss of short-chain fatty-acid-producing Gram-positive bacteria and expansion of Proteobacteria, and a dysregulated immune system. Therapeutic strategies have shifted toward targeted biologics and small molecules to promote mucosal healing. In this review, we recapitulate the mechanistic axes of inflammation, oxidative stress, and senescence in IBD and then critically evaluate emerging targeted therapies. Topics include anti-TNFα, integrin blockade, IL-12/23 and IL-23 inhibition, JAK inhibitors, S1P receptor modulators, microRNA modulation, senomorphics, mesenchymal cell therapy, and microbiome interventions. We endorse biomarker-guided therapy and propose future directions to break the SASP-driven inflammatory loop and mitigate long-term carcinogenic risk.