Inhibition of Trichostatin A on bleomycin induced pulmonary fibrosis in rats

Abstract

Objective To investigate the effects of non selective histone deacetylase inhibitors Trichostatin A (TSA) on bleomycin-induced pulmonary fibrosis.To investigate the effects of non selective histone deacetylase inhibitors TSA on transforming growth factor-β (TGF-β1) mRNA,a-smooth muscle actin (α-SMA),collagen Ⅰ in pulmonary fibrosis rats.Methods SPF level male SD rats weight 160-180 g were selected.46 rats were randomly divided into four groups:ten for normal control group,fourteen for model control group Ⅰ,twelve for model control group Ⅱ and ten for treatment group.Rat pulmonary fibrosis was induced by bleomycin (5 mg/kg) via single intratracheal perfusion in the two model control groups and treatment group.Normal control mice were instilled with a corresponding volume of 0.9％ saline intratracheally.Treatment group was treated by the dilution of TSA 2 mg/kg,DMSO 60 μl and 0.9％ saline 1.2 ml intraperitoneal injection from the next day,once a day for three days.Model control group Ⅱ was treated by the dilution of DMSO 60 μl and 0.9％ saline 1.2 ml intraperitoneal injection from the next day,once a day for three days.Model control group Ⅰ and normal control group were treated by 0.9％ saline 1.2 ml intraperitoneal injection from the next day,once a day for three days.The death were no for normal control group,five for model control group Ⅰ,four for model control group Ⅱ and two for treatment group.All the animals were sacrificed on the 21st day after modeling.The pathological changes were observed by hematoxylin and eosin stain and masson trichrome stain.The lung hydroxyproline (HYP) was measured by alkaline hydrolysis.The expression of TGF-β1 mRNA was measured by real-time PCR.The protein level of α-SMA and collage Ⅰ in lung tissue homogenate was measured by ELISA.Results ① Alveolitis grades of the two model control groups increased compared with the normal control group and treatment group (P ＜ 0.05).There was no significant difference in alveolitis grades between the two model control groups (P ＞0.05).There was no significant difference in alveolitis grades between treatment group and normal control group (P ＞0.05).②Pathological semi-quantitative analysis showed that pulmonary fibrosis degree of the two model control groups increased compared with normal control group and treatment group(P ＜0.05).There was no significant difference in the pulmonary fibrosis degree between the two model control groups (P ＞0.05).There was no significant difference in the pulmonary fibrosis degree between treatment group and normal control group (P ＞0.05).③The HYP level in lung tissue of the two model control groups was higher than normal control group and treatment group (P ＜0.05).There was no significant difference in lung tissue HYP level between the two model control groups (P ＞0.05).There was no significant difference in lung tissue HYP level between treatment group and normal control group (P ＞0.05).④The protein level of α-SMA increased in the two model control groups compared with normal control group and treatment group (P ＜0.05).There was no significant difference in the protein level of α-SMA of lung tissue homogenate between the two model control groups by ELISA (P＞0.05).There was no significant difference in the protein level of α-SMA between treatment group and normal control group (P ＞0.05).⑤The protein level of collagen Ⅰ increased in the two model control groups compared with normal control group and treatment group (P ＜0.05).There was no significant difference in the protein level of collagen Ⅰ of lung tissue homogenate between the two model control groups by ELISA (P ＞0.05).There was no significant difference in the protein level of collagen Ⅰ between treatment group and normal control group (P ＞0.05).⑥The expression of lung tissue TGF-β1 mRNA increased in the two model control groups compared with normal control group (P ＜0.05).There was no significant difference in the expression of lung tissue TGF-β1 mRNA between the two model control groups by real-time PCR (P ＞0.05).The expression of lung tissue TGF-β1 mRNA decreased in the treatment group compared with the two model control groups (P ＜ 0.05).The expression of lung tissue TGF-β1 mRNA increased in treatment group compared with normal control group (P ＜ 0.05).Conclusions Experimental results show that TSA can alleviate pulmonary fibrosis.Non selective histone deacetylase inhibitors TSA can reduce the bleomycin induced pulmonary fibrosis in rats.It can reduce the protein α-SMA,collagen Ⅰ content and TGF-β1 mRNA expression associated with lung tissue fibrosis. Key words: Pulmonary fibrosis; Histone deacetylase inhibitors; α-smooth muscle actin; Collagen Ⅰ; Transforming growth factor-β1