Expression of heat shock protein 70 and drug intervention in rats with septic acute lung injury

Objective To study heat shock protein 70(HSP70)expression in rats with septic acute lung injury(ALI)and to investigate the effect of dexamethasone and the possible mechanisms.Methods Forty-four Wistar rats were randomly divided into sham group(n=12),ALI group(n=16)and dexamethasone(DEX)group(n=16).And rats were sacrificed at 6,12,18 and 24 hours after operation.Pulmonary expression of HSP70 mRNA was assessed by reverse transcription-polymerase chain reaction(RT-PCR),and pulmonary expression of HSP70 protein was assessed by immunohistochemistry.Results Pulmonary expression of HSP70 mRNA and HSP70 protein showed a gradual increase and reached the peak at 18 h after ligation and perforation(CLP).Pulmonary expressions of HSP70 mRNA and HSP70 protein were increased in ALI and DEX groups compared to those in the sham group at all time points(P0.01).Pulmonary expressions of HSP70 mRNA and HSP70 protein were increased in DEX group compared to those in ALI group at all time points(P0.05 or P0.01).There were no significant differences in the pulmonary expression of HSP70 mRNA and HSP70 protein at each time point in the same group(P0.05).Conclusion Expression of HSP70 is increased in acute lung injury induced by sepsis.The effect of dexamethasone on septic acute lung injury may be related to the up-regulation of lung HSP70 mRNA and HSP70 protein expressions.