Over-expression of heat shock protein 70 protects mice against lung ischemia/reperfusion injury through SIRT1/AMPK/eNOS pathway.

Lung ischemia/reperfusion injury (LIRI) usually occurs during in lung transplantation and extracorporeal circulation operation and may develop into pulmonary infections, acute rejection and bronchiolitis obliterans syndrome. Recent studies have discovered the protective effect of heat shock protein 70 (HSP70) on various types of injuries. In the present study, we firstly explore the role of over-expressed HSP70 on the protection against LIRI. Lung Wet/Dry (W/D) ratio, biomarkers in the bronchoalveolar lavage fluid (BALF), lung histological changes and apoptosis markers, oxidative products and proinflammatory cytokines in the lung tissues were analyzed. Next, the expression of eNOS, SIRT1 and AMPK were measured. Finally, the changes of the lung W/D ratio and biomarkers in the BALF using the inhibitors of SIRT1/AMPK/eNOS pathway were evaluated. Mice exposed to LIRI procedure had significant increases in lung W/D ratio and biomarkers (protein level, LDH level, leukocytes and total cells) in BALF. LIRI also caused histological injury, demonstrated by hemorrhage, alveolar septal thickening and fibrin deposition. Apoptosis, oxidative products and proinflammatory cytokines in lung tissue were also induced by LIRI. The over-expression of HSP70 antagonized the impacts of LIRI by attenuating these parameters. It significantly increased the expression of eNOS, SIRT1 and AMPK, while the inhibition of SIRT1 and AMPK deactivated the eNOS expression. The lung W/D ratio and biomarkers in BALF were increased while mice were given inhibitors of eNOS, SIRT1 and AMPK. We concluded that over-expression of HSP70 had protective effect on LIRI and HSP70 might be involved in the protection through a SIRT1/AMPK/eNOS pathway.