Unraveling the Complex Pathogenesis, Diagnosis, and TherapeuticInterventions of Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD), encompassing Crohn’s Disease (CD) and Ulcerative Colitis (UC), is a chronic, relapsing inflammatory condition of the gastrointestinal (GI) tract with complex pathogenesis involving genetic, microbial, immune, and environmental factors. Genetic studies have identified susceptibility loci such as Nucleotide-binding Oligomerization Domaincontaining protein 2 (NOD2) and ATG16L1, while dysbiosis of the gut microbiota and defective immune regulation further exacerbate disease progression. Aberrant activation of innate and adaptive immune cells, including neutrophils, macrophages, innate lymphoid cells, and T-helper subsets, perpetuates mucosal inflammation. Innate immune cells, including neutrophils, macrophages, and innate lymphoid cells, act as early responders to microbial and damage-associated signals, contributing to epithelial barrier dysfunction, cytokine imbalance, and tissue injury. Concurrently, maladaptive activation of adaptive immune cells, particularly Th1, Th17, and hybrid Th1/Th17 subsets, alongside impaired regulatory T-cell function, drives sustained immune activation and mucosal damage. Environmental triggers such as smoking, diet, medications, and psychological and social stress also contribute significantly to disease onset and exacerbation. Diagnosis relies on a multidisciplinary approach combining serological, stool-based, endoscopic, radiologic, and histopathological methods. Current therapeutic strategies include aminosalicylates, corticosteroids, immunomodulators, biologics, microbiome-based interventions (e.g., microecological agents such as probiotics, prebiotics, and synbiotics), fecal microbiota transplantation, antibiotics, and nutritional interventions, each aimed at inducing remission and maintaining mucosal healing in IBD patients. This review provides a comprehensive overview of the immunologic mechanisms underlying IBD pathogenesis, diagnostic strategies, and therapeutic interventions, highlighting current progress and areas requiring further investigation.