Host intestinal barrier and immune system

The host intestinal barrier and immune system is a complex, multi-layered defense network that maintains physiological homeostasis by regulating the passage of nutrients while preventing the entry of harmful pathogens and antigens (Vancamelbeke & Vermeire, 2017, The intestinal barrier: a fundamental role in health and disease). This system includes a physical barrier consisting of mucus layers and epithelial cells linked by tight junctions, which provide a selective seal against the luminal environment (Okumura & Takeda, 2017, Roles of intestinal epithelial cells in the maintenance of gut homeostasis). It also incorporates a biochemical barrier of antimicrobial peptides and secretory IgA, alongside the gut-associated lymphoid tissue (GALT), which houses a vast array of specialized immune cells (Mowat & Agace, 2014, Regional specialization of the mucosal immune system). Dysregulation of these components leads to increased intestinal permeability and aberrant immune activation, which are hallmark features of chronic conditions such as inflammatory bowel disease (IBD) and celiac disease (Ungaro et al., 2017, Ulcerative colitis). While not a single molecular target, this system is the focus of numerous therapies that target specific pathways within it, such as TNF-alpha inhibitors or integrin antagonists, to reduce inflammation and facilitate mucosal repair (Neurath, 2017, Cytokines in inflammatory bowel disease). Therapeutic strategies aim to restore the integrity of the epithelial lining and modulate the local immune response to prevent tissue damage. Challenges in targeting this system include the need for gut-specific delivery and the risk of systemic immunosuppression.

Other names

Gut-associated lymphoid tissueGALTIntestinal mucosal barrierIntestinal epithelial barrierGut immune system

Therapeutic modulation involves the inhibition of pro-inflammatory cytokines, blockade of leukocyte migration to the gut mucosa, and stabilization of the epithelial barrier to restore intestinal homeostasis.