Intestinal epithelial barrier (IEB) (IEB)

The intestinal epithelial barrier, comprising tight junctions and efflux transporters, serves as a critical gatekeeper for the systemic absorption of nutrients and pharmaceuticals while excluding harmful xenobiotics [1]. Tight junctions are complex protein networks, including claudins and occludin, that seal the paracellular space between enterocytes to regulate the passage of ions and water [2]. Efflux transporters, such as P-glycoprotein (ABCB1) and Breast Cancer Resistance Protein (BCRP), are located on the apical membrane and actively pump absorbed drugs back into the intestinal lumen, often limiting the efficacy of oral medications [3]. This dual barrier system is essential for maintaining intestinal homeostasis and protecting against systemic inflammation and infection [4]. Pathological disruption of these components is associated with inflammatory bowel disease (IBD) and celiac disease, where increased permeability allows for the translocation of luminal antigens [5]. In drug development, these systems are targeted to improve the bioavailability of poorly absorbed compounds or to enhance the delivery of drugs to the central nervous system by bypassing similar barriers [6].

Other names

Intestinal tight junction and efflux transportersGut barrierIntestinal mucosal barrierParacellular and transcellular intestinal barrier

Inhibition of efflux transporters (e.g., P-gp, BCRP) to increase drug bioavailability and modulation of tight junction proteins (e.g., claudins, occludin) to enhance paracellular transport.