Protective effect of curcumin on endotoxin-induced acute lung injury in rats

To investigate the protective effect of curcumin on endotoxin-induced acute lung injury in rats, and explore the underlying mechanisms, 24 male Wistar rats were randomly divided into 4 experimental groups: sham-vehicle (S), sham-curcumin (C), lipopolysaccharide (LPS)-vehicle (L), and curcumin-lipopolysaccharide (C-L) groups. The wet/dry (W/D) weight ratio of the lung and bronchoalveolar lavage (BAL) fluid protein content were used as measures of lung injury. Neutrophil recruitment and activation were evaluated by BAL fluid cellularity and myeloperoxidase (MPO) activity in cell-free BAL and lung tissue. The levels of cytokine-induced neutrophil chemoattractant-I (CINC-1) in lung tissues were measured by ELISA. The histopathological changes of lung tissues were observed by using the HE staining. Our results showed that lung injury parameters, including the wet/dry weight ratio and protein content in BALF, were significantly higher in the L group than in the S group (P<0.01). In the L group, higher numbers of neutrophils and greater MPO activity in cell-free BAL and lung homogenates were observed when compared with the S group (P<0.01). There was a marked increase in CINC-1 levels in lung tissues in response to LPS challenge (P<0.01, L group vs S group). Curcumin pretreatment significantly attenuated LPS-induced changes in these indices. LPS caused extensive morphological lung damage, which was also lessened after curcumin pretreatment. All the above-mentioned parameters in the C group were not significantly different from those of the S group. It is concluded that curcumin pretreatment attenuates LPS-induced lung injury in rats. This beneficial effect of curcumin may involves, in part, inhibition of neutrophilic recruitment and activity, possibly through inhibition of lung CINC-1 expression.