Lipopolysaccharide‐induced histone deacetylase activity increases paracellular permeability in human lung microvascular endothelial cells (695.4)

Abstract

Objective: Lipopolysaccharide causes disruption of the endothelial barrier and increases trans‐endothelial permeability. Inhibition of heat shock protein 90 (Hsp90) protects and restores LPS‐mediated trans‐endothelial hyper‐permeability. Hyper‐acetylation of Hsp90 suppresses its chaperone function suggesting a role of HDAC in LPS‐mediated trans‐endothelial permeability. Therefore, we investigated the role of HDAC in LPS‐mediated trans‐endothelial permeability in human lung microvascular endothelial cells (HLMVEC). Method: HDAC activity was measured using the Flour‐de‐lys assay kit and HLMVEC barrier function was measured using gold‐plated electric cell‐substrate impedance sensing (ECIS) arrays. Results: Whole cell lysates from HLMVEC exposed to LPS (0.2, 1 or 5 EU/ml) showed significant increase in HDAC activity compared to vehicle‐treated cells. Cell fractionation revealed that LPS induced HDAC activity in both the cytoplasmic and the nuclear extracts. This LPS‐induced HDAC activity was not inhibited by pre‐treatment with the PI3k/Akt inhibitor, Ly294002 (5µM) or the Hsp90 inhibitor AUY‐922 (2µM), indicating that LPS stimulates HDAC activity independently of Hsp90 or Akt. Additionally, pre‐treatment with either HDAC inhibitor (Trichostatin (TSA), 1 µM or Panobinostat (LBH), 1 µM) protected HLMVEC monolayers from LPS‐mediated hyper‐permeability and attenuated Hsp90 chaperone function by disrupting Hsp90‐CDC37 interaction. Conclusion: LPS induces HDAC activity to promote trans‐endothelial hyper‐permeability possibly via de‐acetylation and activation of the Hsp90 chaperone function. (Supported by HL093460 and HL101902)Grant Funding Source: Supported by HL093460 and HL101902