title: [Anti-fibrotic effects of angiotensin1-7 on bleomycin-induced pulmonary fibrosis in rats].
abstract: OBJECTIVE
  To explore the anti-fibrotic effects of angiotensin (Ang) 1-7 on bleomycin (BLM) -induced pulmonary fibrosis in rats.
  
  
  METHODS
  Eighteen Wistar male rats were randomly divided into 3 groups, including control group (intratracheal instillation with physiological saline and subcutaneous micro-pump with bi-distilled water at the rate of 0.29 µl/h), BLM group (intratracheal instillation with bleomycin and subcutaneous micro-pump with bi-distilled water at the same rate) and BLM+Ang1-7 group (intratracheal instillation with bleomycin and subcutaneous micro-pump with Ang1-7 at a dose of 25 µg·kg(-1) · h(-1) at the same rate). At Day 28, lung tissues were collected. Histological changes of lungs were evaluated by hematoxylin and eosin and Masson's trichrome stains. Collagen content of lung tissues was assessed by hydroxyprolin concentration. Then the products of protein and RNA were collected. And Western blot and realtime polymerase chain reaction (RT-PCR) were used to detect the protein or mRNA of TGF-β1 and α-collagenI. Human embryonic lung fibroblast (HFL-1) was divided into 5 groups: (1) control group: no stimulation; (2) AngII group: stimulation of AngII (10(-7)mol/L) ; (3) Ang1-7 group: stimulation of Ang1-7 (10(-7)mol/L); (4) Ang1-7 plus AngII group: stimulation by AngII (10(-7)mol/L) with Ang1-7 (10(-7)mol/L) pre-treatment; (5) Ang1-7+AngII+A-779 group: stimulation by AngII and Ang1-7 (10(-7) mol/L) with Mas receptor inhibitor A-779 (10(-6)mol/L) pre-treatment. Then the products of protein and RNA were collected. And QuantiGene and RT-PCR were used to detect the activation of TGF-β1, and α-collagenI mRNA.
  
  
  RESULTS
  Compared with control group, fibrosis score and hydroxyproline concentrations increased significantly in BLM group, but declined in BLM+Ang1-7 group. The difference was statistically significant (P < 0.05). TGF-β1 mRNA, α-collagenI mRNA and α-collagenI protein level were up-regulated by BLM (4.45 ± 0.45 vs 1.00 ± 0.20, 5.14 ± 0.55 vs 1.00 ± 0.08, 1.48 ± 0.34 vs 0.23 ± 0.11) (all P < 0.05); while compared with BLM group, those of BLM+Ang1-7 group were down-regulated (2.80 ± 0.35, 3.10 ± 0.52, 0.49 ± 0.11) (all P < 0.05). In vitro: TGF-β1 mRNA and α-collagen I mRNA level were up-regulated by AngII (1.67 ± 0.26 vs 1.00 ± 0.10, 4.86 ± 1.36 vs 1.46 ± 0.54) (all P < 0.05); while those of AngII+Ang1-7 group were down-regulated (0.91 ± 0.30, 1.57 ± 0.27) compared with AngII group (all P < 0.05); no significant difference existed between the AngII+Ang1-7+A-779 group (1.25 ± 0.14, 1.29 ± 0.49) and AngII+Ang1-7 group (P > 0.05).
  
  
  CONCLUSIONS
  Ang1-7 has anti-fibrous effect upon bleomycin-induced pulmonary fibrosis in rats and such an effect of Ang1-7 may be associated with AngII-induced expression of TGF-β1.
authors.affiliation: Department of Respiratory Disease, South Medical University, Guangzhou, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Meng
authors.forename: Chang-hui
authors.initials: CH
authors.lastname: Yu
authors.forename: Shao-xi
authors.initials: SX
authors.lastname: Cai
authors.forename: Xu
authors.initials: X
authors.lastname: Li
mesh_terms: D000803:Angiotensin I / Q000494:pharmacology*; D000818:Animals; D001761:Bleomycin / Q000009:adverse effects; D024042:Collagen Type I / Q000378:metabolism; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
chemical_list: D024042:Collagen Type I; D010446:Peptide Fragments; C508962:Tgfb1 protein, rat; D053773:Transforming Growth Factor beta1; D001761:Bleomycin; D000803:Angiotensin I; C118790:angiotensin I (1-7)