Impact of hypothermia on Toll-like receptor 2 protein expression and downstream inflammatory mediators during acute lung injury

doi:10.3969/j.issn.1002-1949.2015.02.018

Abstract：Objective To investigate the impact of hypothermia ( HT ) on TLR2 protein expression and downstream inflammatory mediators during acute lung injury (ALI).Methods Ninety male SD rats were randomly divided into four groups. The ALI model was reproduced by LPS intratracheal instillation ( hypothermia group, HT; temperature-controlled group, TC; temperature-uncontrolled group, UTC);saline was instilled intratracheally for control group.In HT group and control temperature group the body temperature was respectively maintained to 33~34℃and 36~37℃1 hour after LPS instillation.All the subject were sacrificed after LPS or saline instillation for 2 h, 7 h, 13 h. The morphological changes in lung tissue of rats were observed under light microscope.TLR2 protein expression, myeloid differentiation factor88 ( Myd88 ) , tumour necrosis factor -α( TNF -α) and inducible nitric oxide synthase ( iNOS) mRNA transcriptional level was determined by western blot and reverse transcription-polymerase chain reaction ( RT-PCR) .Results With the intervention of LPS, oxygen partial pressure of each group was decreased obviously; score of morphological changes in lung tissue was increased significantly TLR2 protein expression, Myd88, TNF -αand iNOS mRNA transcription in HT group, TC group and UTC group was in exhibited an increased trend ( both P<0.01) .At 1 hour and 6 hour, oxygen partial pressure in hypothermia group was higher than that in TC group and UTC group (both P<0.05);at 12 hour, oxygen partial pressure in HT group and UTC group showed no difference (both P>0.05).At the same time, score of morphological changes in lung tissue in hypothermia group was lower than that in TC group and UTC group (both P<0.01); TLR2 protein expression in hypothermia group was lower than that in TC group and UTC group ( both P <0.01 );Myd88 mRNA expression ( 2 -ΔΔCT ) in hypothermia group was lower than that in TC group and UTC group (both P<0.01);TNF-αmRNA expression (2 -ΔΔCT) in hypothermia group was lower than that in TC group and UTC group (both P<0.01);iNOS mRNA expression (2 -ΔΔCT) in hypothermia group was lower than that in TC group and UTC group ( both P <0.01 ) .Conclusion Hypothermia may downregulate TLR2 protein expression, Myd88, iNOS and TNF-αmRNA transcription level and reduce lung injury of endotoxin-induced ALI in rats.