Toll-like receptor 4 regulates heme oxygenase-1 expression after hemorrhagic shock induced acute lung injury in mice: requirement of p38 mitogen-activated protein kinase activation

Shock. 2009 May;31(5):486-92. doi: 10.1097/SHK.0b013e318188f7e1.

Abstract

Acute lung injury (ALI) leading to respiratory distress is a common sequela of shock or trauma. The toll-like receptors (TLRs) stand at the interface of innate immune activation in the settings of both infection and sterile injury by responding to a variety of microbial and endogenous ligands alike. This work explored the effects of TLR-4 on hemorrhage-induced ALI and characterizes the signaling pathways and the mechanisms involved in noninfectious ALI. Mice underwent hemorrhagic shock and resuscitation (HSR). Arterial blood gases; expressions of TLR-4, heme oxygenase 1 (HO-1), and p38 mitogen-activated protein kinase (p38MAPK); myeloperoxidase activity; lung wet/dry ratios; and IL-10 levels in lung tissues were obtained at 6, 24, and 48 h after HSR. Hemorrhagic shock and resuscitation induced significant expressions of TLR-4, HO-1, and p38MAPK in C3H/HeN mice. IL-10 and myeloperoxidase were markedly increased at 24 h after HSR, and C3H/HeN mice had ALI with PaO2/fraction of inspired oxygen less than 300 mmHg. The induced amount of each cytokine level and the expressions of TLR-4, HO-1, and p38MAPK of C3H/HeN mice were significantly higher compared with C3H/HeJ mice. This study demonstrated that lung p38MAPK is activated after HSR, and p38MAPK inhibitor FR167653 suppresses HO-1 induction after ALI. We concluded that TLR-4 might induce HO-1 messenger RNA expression, which is probably involved in p38MAPK activation in the development of the lung dysfunction after HSR.

MeSH terms

  • Acute Lung Injury / etiology*
  • Acute Lung Injury / metabolism*
  • Acute Lung Injury / pathology
  • Acute Lung Injury / physiopathology
  • Animals
  • Blotting, Western
  • Disease Models, Animal
  • Gene Expression Regulation*
  • Heme Oxygenase-1 / genetics
  • Heme Oxygenase-1 / metabolism*
  • Immunohistochemistry
  • Interleukin-10 / metabolism
  • Lung / metabolism
  • Lung / pathology
  • Male
  • Mice
  • Mice, Inbred C3H
  • Microscopy
  • Reverse Transcriptase Polymerase Chain Reaction
  • Shock, Hemorrhagic / physiopathology*
  • Time Factors
  • Toll-Like Receptor 4 / metabolism
  • Toll-Like Receptor 4 / physiology*
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism*

Substances

  • Toll-Like Receptor 4
  • Interleukin-10
  • Heme Oxygenase-1
  • p38 Mitogen-Activated Protein Kinases