Regulatory effects of endogenous sulfur dioxide on collagen accumulation in pulmonary artery fibroblasts of rats and its mechanisms

Abstract

Objective To investigate the regulatory effects of endogenous sulfur dioxide (SO2) on collagen accumulation in pulmonary arterial fibroblasts of rats and its mechanisms. Methods Primary rat pulmonary artery fibroblasts were used in the experiment and were divided into 3 groups: the control group, the L-aspartate-beta -hydroxamate(HDX) group and the HDX+ SO2 group.SO2 content of pulmonary artery fibroblasts supernatant was detected by adopting high performance liquid chromatography (HPLC). Collagen type Ⅰ and collagen type Ⅲ in pulmonary artery fibroblasts were determined by using immunofluorescence.Phosphorylation of Smad2/3, protein expression of matrix metalloproteinase (MMP)-13 and tissue inhibitors of MMP (TIMP)-1 were detected by using Western blot.One-way ANOVA was used for multiple group comparisons followed by Bonferroni test for each group.P<0.05 was considered as significant difference. Results Compared with control group, endogenous SO2 content in HDX group was significantly decreased [(14.30±0.48) μmol/L vs.(20.14±0.49) μmol/L, P<0.01], the level of Smad2/3 increased (1.03±0.31 vs.0.48±0.20, P<0.01), protein expressions of MMP-13 and TIMP-1 in pulmonary artery fibroblasts were decreased (MMP-13: 0.28±0.06 vs.0.75±0.11, P<0.01; TIMP-1: 0.40±0.05 vs.0.66±0.20, P<0.01), and the ratio of MMP-13/TIMP-1 was decreased (0.71±0.12 vs.1.23±0.45, P<0.01). However, contents of collagen Ⅰ and collagen Ⅲ were significantly increased.Compared with HDX group, the level of Smad2/3 phosphorylation in HDX+ SO2 group decreased (0.57±0.16 vs.1.03±0.31, P<0.01), protein expression of MMP-13 and TIMP-1 upregulated (MMP-13: 0.63±0.06 vs.0.28±0.06, P<0.01; 0.59±0.11 vs.0.40±0.05, P=0.015), the ratio of MMP-13/TIMP-1 (1.10±0.22 vs.0.71±0.12, P=0.033) increased, but contents of collagen type Ⅰ and type Ⅲ were reduced obviously. Conclusions SO2 promotes the degradation of collagen and collagen accumulation in pulmonary artery fibroblasts of rats probably by inhibiting Smad2/3 signal pathway, increasing protein expression of MMP-13 and TIMP-1, and upregulating the ratio of MMP-13/TIMP-1. Key words: Sulfur dioxide; Collagen; Fibroblasts