Tight junction protein complex at the blood–brain barrier (BBB-TJ complex)

The tight junction protein complex at the blood–brain barrier (BBB) is a specialized assembly of transmembrane and cytoplasmic proteins that seal the paracellular space between endothelial cells (PMID: 23415110). Key components include claudins (especially claudin-5), occludin, and junctional adhesion molecules (JAMs), which are linked to the actin cytoskeleton via zonula occludens (ZO) scaffolding proteins (PMID: 12535520). This complex is essential for maintaining the high electrical resistance and selective permeability of the BBB, protecting the brain from toxins and pathogens while regulating nutrient transport (PMID: 28844075). Dysfunction of these proteins is a hallmark of several neurological disorders, including stroke, multiple sclerosis, and Alzheimer's disease, where barrier breakdown contributes to edema and neurodegeneration (PMID: 30124561). In drug development, this complex is a target for transient modulation to allow the passage of large or polar therapeutic agents into the brain (PMID: 21917916). Conversely, stabilizing these junctions is a therapeutic strategy to treat conditions characterized by excessive BBB permeability and neuroinflammation (PMID: 19233542).

Other names

Blood-brain barrier tight junctionsBBB tight junctionParacellular barrier of the BBBCerebrovascular tight junctionEndothelial tight junction

Transient disruption of paracellular seals through osmotic stress, receptor-mediated signaling (e.g., Adenosine A2A or Bradykinin B2 agonism), or direct modulation of junctional proteins to facilitate drug delivery to the central nervous system (PMID: 21917916, StatPearls: Osmotic Diuretics).