Intestinal epithelial tight junction complex (TJ)

The intestinal epithelial tight junction (TJ) complex is a highly dynamic multi-protein structure that forms a continuous seal between adjacent epithelial cells, serving as the primary determinant of the paracellular barrier (PubMed: 19112186). It is composed of transmembrane proteins, including claudins, occludin, and junctional adhesion molecules (JAMs), which interact with cytosolic scaffold proteins like zonula occludens (ZO-1, ZO-2, and ZO-3) to link the complex to the actin cytoskeleton (StatPearls: NBK547712). These complexes are essential for maintaining the intestinal mucosal barrier, preventing the translocation of luminal antigens, toxins, and microbes into the systemic circulation while selectively allowing the passage of ions and water (PubMed: 23426535). Dysfunction of the TJ complex is a hallmark of several gastrointestinal and systemic diseases, including inflammatory bowel disease (IBD) and celiac disease, where increased permeability leads to chronic immune activation (PubMed: 22109896). Pharmacological targeting of TJs involves either the use of tightening agents like larazotide acetate to restore barrier function or opening agents to enhance the oral bioavailability of poorly permeable macromolecular drugs (PubMed: 25107293).

Other names

Zonula occludensOccluding junctionIntestinal mucosal barrierParacellular barrier complex

Modulation of paracellular permeability through the antagonism of zonulin receptors or the stabilization and upregulation of transmembrane proteins like claudins and occludin.