Pulmonary endothelial barrier (PEB)

The pulmonary endothelial barrier is a specialized semi-permeable interface between the pulmonary circulation and the lung tissue, primarily formed by a monolayer of endothelial cells and their associated junctional complexes (PubMed: 28630044). Its fundamental biological role is to maintain fluid homeostasis and regulate the selective passage of solutes and leukocytes into the alveolar space, which is essential for efficient gas exchange (NIH: PMC4372489). In conditions like Acute Respiratory Distress Syndrome (ARDS) and sepsis, the barrier is compromised by inflammatory mediators, leading to vascular leakage, protein-rich edema, and impaired oxygenation (StatPearls: NBK436002). Pharmacological interventions targeting this barrier aim to restore its integrity by stabilizing adherens junctions (e.g., VE-cadherin) or activating protective pathways such as Tie2 and S1P1 signaling (Nature Communications: 10.1038/s41467-017-00116-w). While it is a physiological structure rather than a single protein, it serves as a critical therapeutic focus for mitigating life-threatening pulmonary edema and systemic inflammation.

Other names

Alveolar-capillary barrierLung endothelial barrierPulmonary microvascular endothelial barrierBlood-gas barrier

Stabilization of endothelial adherens junctions; Activation of Tie2 receptor signaling; Modulation of sphingosine-1-phosphate (S1P) receptors; Inhibition of RhoA-mediated cytoskeletal contraction