Unfractionated heparin ameliorates pulmonary microvascular endothelial barrier dysfunction via microtubule stabilization in acute lung injury

Respir Res. 2018 Nov 15;19(1):220. doi: 10.1186/s12931-018-0925-6.

Abstract

Background: Endothelial barrier dysfunction is central to the pathogenesis of sepsis-associated acute lung injury (ALI). Microtubule (MT) dynamics in vascular endothelium are crucial for the regulation of endothelial barrier function. Unfractionated heparin (UFH) possesses various biological activities, such as anti-inflammatory activity and endothelial barrier protection during sepsis.

Methods: Here, we investigated the effects and underlying mechanisms of UFH on lipopolysaccharide (LPS)-induced endothelial barrier dysfunction. C57BL/6 J mice were randomized into vehicle, UFH, LPS and LPS + UFH groups. Intraperitoneal injection of 30 mg/kg LPS was used to induce sepsis. Mice in the LPS + UFH group received intravenous UFH 0.5 h prior to LPS injection. Human pulmonary microvascular endothelial cells (HPMECs) were cultured for analyzing the effects of UFH on LPS-induced and nocodazole-induced hyperpermeability, F-actin remodeling, and LPS-induced p38 MAPK activation.

Results: UFH pretreatment significantly attenuated LPS-induced pulmonary histopathological changes, and increased the lung W/D ratio and Evans blue accumulation in vivo. Both in vivo and in vitro studies showed that UFH pretreatment blocked the LPS-induced increase in guanine nucleotide exchange factor (GEF-H1) expression and myosin phosphatase target subunit 1 (MYPT1) phosphorylation, and microtubule (MT) disassembly in LPS-induced ALI mouse model and human pulmonary microvascular endothelial cells (HPMECs). These results suggested that UFH ameliorated LPS-induced endothelial barrier dysfunction by inhibiting MT disassembly and GEF-H1 expression. In addition, UFH attenuated LPS-induced hyperpermeability of HPMECs and F-actin remodeling. In vitro, UFH pretreatment inhibited LPS-induced increase in monomeric tubulin expression and decrease in tubulin polymerization and acetylation. Meanwhile, UFH ameliorates nocodazole-induced MTs disassembly and endothelial barrier dysfunction.Additionally, UFH decreased p38 phosphorylation and activation, which was similar to the effect of the p38 MAPK inhibitor, SB203580.

Conclusions: UFH exert its protective effects on pulmonary microvascular endothelial barrier dysfunction via microtubule stabilization and is associated with the p38 MAPK pathway.

Keywords: ALI; Cell cytoskeleton; Endothelial permeability; GEF-H1; Microtubule; Unfractionated heparin.

MeSH terms

  • Acute Lung Injury / drug therapy*
  • Acute Lung Injury / metabolism
  • Animals
  • Capillary Permeability / drug effects*
  • Capillary Permeability / physiology
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / pathology
  • Heparin / metabolism
  • Heparin / pharmacology*
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microtubules / drug effects*
  • Microtubules / metabolism
  • Microtubules / pathology
  • Microvessels / drug effects*
  • Microvessels / metabolism
  • Microvessels / pathology
  • Protein Stability / drug effects

Substances

  • Heparin