Intracellular Delivery Of Activated Focal Adhesion Kinase - A Novel Therapeutic Strategy For Acute Lung Injury

Lung microvascular barrier deterioration is a major cause of acute lung injury (ALI). Tyrosine phosphorylation of the protein, focal adhesion kinase (FAK), enhances the endothelial barrier in cultured lung endothelial monolayers (JBC, 278:13342–9). To determine whether phosphorylated FAK (FAKp) is barrier protective in vivo, we non-covalently conjugated purified, His-tagged FAKp to the cell-permeable peptide, TAT (TAT-FAKp). To quantify microvascular barrier properties in an ALI model, in anesthetized mice we intra-tracheally instilled 0.1N HCl (2 ml/kg). Controls received no instillation. After 2 hours, we isolated and blood-perfused lungs to quantify lung microvascular barrier properties in terms of the filtration coefficient (Kf). Kf was 0.3-±0.1 ml/(cmH2O.min.100g) for controls (mean±SD; n=3), but higher at 0.7±0.1 after acid instillation (n=3), indicating that acid deteriorated the barrier. In animals given tail vein infusion of TAT-FAKp (500 ug/kg) 4 hours prior to, or 0.5 hours following acid instillation (n=5 for each), the Kf increase was blunted by 80±4% (P<0.05). These results indicate that TAT-FAKp treatment abrogated acid induced deterioration of the lung microvascular barrier and that the protective effect lasted at least 4 hours. We propose that TAT-FAKp might be a novel therapeutic agent in ALI (HL36024).