Hsp90 inhibition prevents bacterial lipopolysaccharide‐induced and RhoA‐mediated signaling leading to paracellular hyper‐permeability in human lung microvascular endothelial cells

Abstract

We have previously shown that hsp90 inhibitors protect and restore bacterial lipopolysaccharide (LPS) ‐ mediated barrier dysfunction of human lung microvascular endothelial cells (HLMVEC). Since RhoA is a well‐known mediator of endothelial barrier dysfunction, we investigated the role of hsp90 in LPS‐induced and RhoA mediated HLMVEC hyper‐permeability. LPS (1 EU/ml) challenge of HLMVEC significantly increased RhoA tyrosine nitration and RhoA activity. Pre‐treatment (1 hr) with the hsp90 inhibitor, 17‐AAG (2 uM) suppressed both RhoA nitration and RhoA activity. Pre‐treatment with GSK429286 (10 uM), an inhibitor of the RhoA effector, Rho kinase (ROCK) partially rescued the LPS‐mediated HLMVEC hyper‐permeability, as reflected in changes in transendothelial electrical resistance (TER) of HLMVEC monolayers. Furthermore, GSK429286 pretreatment abolished the LPS‐induced phosphorylation of both CREB (Ser133) and STAT3 (Tyr705), two pro‐inflammatory transcription factors regulated by hsp90. These data suggest that the barrier protective effects of Hsp90 inhibition in HLMVEC involve suppression of RhoA‐ROCK signaling and inhibition of CREB and STAT3. (Supported by HL093460 and HL101902)