Lipopolysaccharide impairs permeability of pulmonary microvascular endothelial cells via Connexin40.

Abstract

The endotoxin lipopolysaccharide (LPS)-induced pulmonary endothelial barrier disruption is a key pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). However, the molecular mechanisms underlying LPS-impaired permeability of pulmonary microvascular endothelial cells (PMVECs) are not fully understood. Gap junctions, particularly Connexin40 (Cx40), are necessary for the maintenance of normal vascular function. In this study, we for the first time investigated the role of Cx40 in LPS-impaired permeability of PMVECs and provided potential therapeutic approaches based on mechanistic findings of Cx40 regulation by LPS stimuli. Rat PMVECs were isolated, cultured and identified with cell morphology, specific markers, ultrastructural characteristics and functional tests. Western blot analysis demonstrated that Cx40 is the major connexin highly expressed in PMVECs. Furthermore, by inhibiting Cx40 in a time-dependent manner, LPS impaired gap junction function and induced permeability injury of PMVECs. The key role of Cx40 decline in mediating detrimental effects of LPS was further confirmed in rescue experiments through Cx40 overexpression. Mechanistically, LPS stress on PMVECs inhibited the protein kinase C (PKC) pathway, which may synergize with the inflammatory nuclear factor kappaB (NFκB) signaling activation in suppressing Cx40 expression level and phosphorylation. Moreover, through pharmacological PKC activation or NFκB inhibition, Cx40 activity in PMVECs could be restored, leading to maintained barrier function under LPS stress. Our findings uncover a previously unrecognized role of Cx40 and its regulatory mechanisms in impaired endothelial integrity under endotoxin and inflammation, shedding light on intervention approaches to improve pulmonary endothelial barrier function in ALI and ARDS.

• Authors: Hua-Song Zhou, Meng Li, Bing-Dong Sui, Lei Wei, Rui Hou, Wen-Sheng Chen, Qiang Li, Sheng-Hui Bi, Jin-Zhou Zhang, Ding-Hua Yi
• Journal: Microvascular research (Microvasc Res) Vol. 115 Pg. 58-67 (01 2018) ISSN: 1095-9319 [Electronic] United States
• PMID: 28870649 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2017 Elsevier Inc. All rights reserved.

Chemical References

• Connexins
• Lipopolysaccharides
• NF-kappa B
• lipopolysaccharide, Escherichia coli O111 B4
• Protein Kinase C

Topics

• Animals
• Capillary Permeability (drug effects)
• Cells, Cultured
• Connexins (genetics, metabolism)
• Dose-Response Relationship, Drug
• Endothelial Cells (drug effects, metabolism, pathology)
• Gap Junctions (drug effects, metabolism, pathology)
• Lipopolysaccharides (toxicity)
• Lung (blood supply)
• Microvessels (drug effects, metabolism, pathology)
• NF-kappa B (metabolism)
• Phosphorylation
• Protein Kinase C (metabolism)
• Rats
• Signal Transduction (drug effects)
• Time Factors
• Gap Junction alpha-5 Protein