| ObjectiveTo study the effects of curcumin on the expression of rat hemeoxygenase (HO)-1 on experimental acute lung injury (ALI), and explore the regulation of HO-1 on the the expression of pro-inflammatory cytokines TNF-a, IL-1βand IL-6Methods40 rats were randomly divided into 5 groups:group A (control group):lingual vein injection of saline; group B (ALI model group): injection of LPS (5mg/Kg) to build ALI model by body weight of mice; group C (curcumin+LPS group):the curcumin (50mg/kg) injection of 15min after LPS; group D [LPS+curcumin+hemin (Hm)]:supplement of Hm (10 mg/Kg) on the basis of group C; group E [LPS+ curcumin+zinc protoporphyrin (ZnPP)]:supplement of ZnPP(10 mg/Kg). Then examined the pathological changes of lung tissue with unaided eyes and microscope, detected the levels of TNF-a, IL-1(3 and IL-6 of for lung tissue lavage fluid (BALF) by immune enzyme assay (ELISA), measured lung wet dry weight ratio (W/D) and malondialdehyde (MDA), detected HO-1 activity in lung tissue, and detected mRNA and protein expression levels of HO-1 in lung tissue by reverse transcription PCR (RT-PCR) and Western blot. Results1. Histopathological changes of ALIIn group A, the appearance of was light red, and had smooth envelope and surface without swelling and bleeding. Under the microscopic, alveolar cells and bronchial lumen didn't exist significant cells and exudations. In group B, lung increased and surface congested. The pathological changes were as following:interstitial lung disease, the dilation and congestion of pulmonary capillaries, widened alveolar septum, the leakage and aggregation of a large number of white blood cells. In the group C and group D, they relieved at some degree, reduced inflammatory cell and alveolar exudation, and had the complete alveolar structure.2. The change of ratio of wet to dry and MDA content of lung tissueThe ratio of W/D were (3.96±0.44) and (4.92±0.37) in lung tissue before and after injection of LPS, by statistical analysis, P<0.05. After the treatment of curcumin, compared with the group B and group E, W/D ratio was statistically significant.The MDA content of lung tissue was higher (P<0.05) than the control group 2 h after LPS injection, and it was higher after 6 injection h and 12 h later (all P<0.05). In group C and group D, MDA were significantly lower than the corresponding LPS group (P<0.05), and in group E, MDA were higher than the corresponding LPS group. 3. The levels of TNF-a, IL-1 p and IL-6 in BLAFIn the ALI model group, the lever of TNF-α, IL-1βand IL-6 were (1563±36) pg/ml, (172±12) pg/ml and (402±36) pg/ml in BALF; After the treatment of curcumin, they were (965±42) pg/ml, (114±7) pg/ml and (153±16) pg/ml separately; ZnPP can reverse the reduction of the effect of curcumin on IL-1βand IL-6 but had no significant effect of TNF-a levels.4.The activity of HO-1, mRNA level and protein expression6 h and 12 h after the treatment of medication, group C and group D, in lung tissue, HO-1 activity were (782.45±33.41) nmol/h.mg.protein, (892.18±62.44) nmol/h.mg.protein and (869.71±64.72) nmol/h.mg. protein, (966.79±52.81) nmol/h.mg.protein separately, significantly higher than that of B group (P<0.05);in group E, in lung tissue,HO-1 activity was lower than LPS group (P<0.05).In the group C, the expression lever of mRNA of HO-1 gene was significantly higher than the LPS group, but slightly lower than group D (LPS+curcumin+Hm group). In the group E, compared with the control group, it had no significant difference. The internal reference (3-actin mRNA level in all treatment groups were constant.Western blotting results indicated that, after the treatment of LPS, protein expression of HO-1 increased, and curcumin could further increase the amount of HO-1. In the group E, compared with the A, it had no significant change. Conclusions1. Curcumin can effectively improve the ALI pulmonary pathological conditions, reduce the content of MDA and TNF-α, IL-1βand IL-6 in BALF, increase the activity of HO-1, and promote its expression of mRNA and protein.2. Protective effects of curcumin on ALI are related to the increased expression of HO-1, and the latter may play a protective role by inhibiting IL-1βand IL-6 levels. |
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