[The effect of curcumin on bleomycin-induced pulmonary fibrosis in rats]

To observe the effect and mechanism of curcumin on pulmonary fibrosis induced by bleomycin in rats.

Fifty-four SD rats were randomly divided into 3 groups, 18 rats each group. The control group received a single intratracheal dose of 2 ml/kg of sterile physiological saline at day 0, and from 14 d, 0.5 ml/kg of sterile physiological saline intraperitoneally every day. The bleomycin group received a single intratracheal dose of 5 mg/kg of bleomycin A(5), and from 14 d, 0.5 ml/kg of suspension of 6% alcohol and 6% polyethylene glycol intraperitoneally every day. The curcumin group received a single intratracheal dose of 5 mg/kg of bleomycin A(5), and from 14 d, 50 mg/kg of curcumin (suspended in 6% alcohol and 6% polyethylene glycol) intraperitoneally every day. Six rats in each group were killed at day 17, 21, 28 in batches. The sections of lungs were stained with hematoxylin-eosin (HE) and Masson's trichrome to evaluate the severity of alveolitis and pulmonary fibrosis. The content of hydroxyproline and the expression of transforming growth factor-beta(1) (TGF-beta(1)) mRNA, interferon-gamma (IFN-gamma) mRNA in lung tissues were analyzed. The concentration of TGF-beta(1) and IFN-gamma in bronchoalveolar lavage fluid (BALF) were measured.

(1) The scores of alveolitis in the curcumin group and the bleomycin group at day 28 were 1.3 +/- 0.5, 2.0 +/- 0.9, respectively, the difference being significant (q = 3.26, P < 0.05). (2) The scores of pulmonary fibrosis in the curcumin group and the bleomycin group were 1.3 +/- 0.5, 1.8 +/- 0.4 at day 21, and 1.2 +/- 0.4, 2.2 +/- 1.0 at day 28, the difference being significant between the two groups (q = 3.33, 4.00, all P < 0.05). (3) The content of hydroxyproline in lung tissues in the curcumin group and the bleomycin group were (1.75 +/- 0.36) microg/g, (2.47 +/- 0.24) microg/g at day 28, the difference being significant (q = 7.20, P < 0.01). (4) The concentration of TGF-beta(1) in BALF in the curcumin group and the bleomycin group were (20 +/- 3) ng/L, (39 +/- 7) ng/L at day 21, and (24 +/- 4) ng/L, (40 +/- 7) ng/L at day 28, all being statistically different between the two groups (q = 5.30, 6.27, all P < 0.05). (5) The expression of TGF-beta(1) mRNA in lung tissues in the curcumin group and the bleomycin group were 0.51 +/- 0.11, 0.59 +/- 0.13 at day 21, and 0.50 +/- 0.07, 0.64 +/- 0.11 at day 28, all being not statistically different between the two groups (q = 1.55, 3.13, all P > 0.05). (6) The concentrations of IFN-gamma in BALF in the curcumin group and the bleomycin group were 0.49 +/- 0.17, 0.50 +/- 0.08 at day 21, and 0.52 +/- 0.15, 0.52 +/- 0.11 at day 28, all being not statistically different between the two groups (q = 1.85, 2.03, all P > 0.05). (7) The expression of IFN-gamma mRNA in the curcumin group and the bleomycin group were (28 +/- 5) ng/L, (35 +/- 13) ng/L at day 21, and (30 +/- 11) ng/L, (39 +/- 13) ng/L at day 28, no significant difference between the two groups (q = 0.17, 0.00, all P > 0.05).

Curcumin can alleviate alveolitis and pulmonary fibrosis induced by bleomycin in rats, possibly through its inhibition of TGF-beta(1).