TLR4 activation of TRPC6-dependent calcium signaling mediates endotoxin-induced lung vascular permeability and inflammation

• Published in: The Journal of experimental medicine Vol. 209; no. 11; pp. 1953 - 1968
• Main Authors: Tauseef, Mohammad, Knezevic, Nebojsa, Chava, Koteswara R, Smith, Monica, Sukriti, Sukriti, Gianaris, Nicholas, Obukhov, Alexander G, Vogel, Stephen M, Schraufnagel, Dean E, Dietrich, Alexander, Birnbaumer, Lutz, Malik, Asrar B, Mehta, Dolly
• Format: Journal Article
• Language: English
• Published: United States The Rockefeller University Press 22.10.2012
• Subjects: Animals; Bone Marrow Transplantation; Calcium - metabolism; Calcium Signaling; Capillary Permeability - drug effects; Cells, Cultured; Cytokines - metabolism; Diglycerides - metabolism; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Immunoblotting; Immunohistochemistry; Inflammation - chemically induced; Inflammation - metabolism; Interleukin-1 Receptor-Associated Kinases - metabolism; Lipopolysaccharides - toxicity; Lung - blood supply; Lung - drug effects; Lung - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Myeloid Differentiation Factor 88 - metabolism; Myosin-Light-Chain Kinase - genetics; Myosin-Light-Chain Kinase - metabolism; NF-kappa B - metabolism; Protein Binding; Toll-Like Receptor 4 - metabolism; TRPC Cation Channels - genetics; TRPC Cation Channels - metabolism; TRPC6 Cation Channel
• ISSN: 0022-1007; 1540-9538
• DOI: 10.1084/jem.20111355

Lung vascular endothelial barrier disruption and the accompanying inflammation are primary pathogenic features of acute lung injury (ALI); however, the basis for the development of both remains unclear. Studies have shown that activation of transient receptor potential canonical (TRPC) channels induces Ca(2+) entry, which is essential for increased endothelial permeability. Here, we addressed the role of Toll-like receptor 4 (TLR4) intersection with TRPC6-dependent Ca(2+) signaling in endothelial cells (ECs) in mediating lung vascular leakage and inflammation. We find that the endotoxin (lipopolysaccharide; LPS) induces Ca(2+) entry in ECs in a TLR4-dependent manner. Moreover, deletion of TRPC6 renders mice resistant to endotoxin-induced barrier dysfunction and inflammation, and protects against sepsis-induced lethality. TRPC6 induces Ca(2+) entry in ECs, which is secondary to the generation of diacylglycerol (DAG) induced by LPS. Ca(2+) entry mediated by TRPC6, in turn, activates the nonmuscle myosin light chain kinase (MYLK), which not only increases lung vascular permeability but also serves as a scaffold to promote the interaction of myeloid differentiation factor 88 and IL-1R-associated kinase 4, which are required for NF-κB activation and lung inflammation. Our findings suggest that TRPC6-dependent Ca(2+) entry into ECs, secondary to TLR4-induced DAG generation, participates in mediating both lung vascular barrier disruption and inflammation induced by endotoxin.