OBJECTIVETo explore the effect of curcumin (CUR) on cycteinyl aspirate specific protease-12 (Caspase-12) and pneumocyte apoptosis in pulmonary ischemia/reperfusion (I/R) injury mice.

METHODSThe in vivo unilateral in situ pulmonary I/R injury mouse model was established in C57BL/6J mice. Sixty experimental mice were randomly divided into six groups by random digit table, i. e., the sham-operation group (Sham), the I/R group, the I/R + dimethyl sulfoxide group (I/R + DMSO), the I/R + low dose CUR pre-treated group (I/R + CUR-100), the I/R + middle dose CUR pre-treated group (I/R + CUR-150), the I/R + high dose CUR pre-treated group (I/R + CUR-200), 10 in each group. Mice were euthanized and their left lungs were excised. Wet lung weight to dry lung weight (W/D) and the total lung water content (TLW) were tested. The morphological changes of the lung tissue were observed and index of quantitative evaluation for alveolar damage (IQA) detected under light microscope. The ultra-microstructure of the lung tissue was observed under electron microscope. The mRNA and protein expression levels of Caspase-12 and glucose regulated protein (GRP78) were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Apoptosis index (AI) of the lung tissue was determined by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) method.

RESULTSCompared with the Sham group, expression levels of Caspase-12, GRP78 mRNA and protein all significantly increased in the I/R group (P < 0.05); W/D, TLW, IQA, and AI were all notably higher (P < 0.05, P < 0.01); the morphological and ultrastructural injury of the lung tissue were notably observed in I/R group. Compared with the I/R + DMSO group, expression levels of GRP78 mRNA and protein were increasingly higher in the I/R + CUR-100 group, the I/R + CUR-150 group, and the I/R +CUR-200 group (P < 0.05), expression levels of Caspase-12 mRNA and protein were lower (P < 0.05); W/D, TLW, IQA, and AI also decreased (P < 0.05, P < 0.01); the morphological and ultrastructural injury of the lung tissue were gradually alleviated in the I/R + CUR groups.

CONCLUSIONCUR had better effect on the lung protection against I/R injury, which might be related to inhibition for pneumocyte apoptosis associated with Caspase-12 in excessive unfolded protein response (UPR).