Role of TGFβ1/Smad3 signaling pathway-mediated lysine hydroxylase 2 activity in collagen deposition of pulmonary fibrosis

AIM: To investigate the effect of TGFβ1/Smad3 signaling pathway on the changes of lysyl hydro-xylase2 (LH2) activity, and to study the role in the relationship between LH2 and collagen deposition of pulmonary fibrosis. METHODS: Human lung fibroblast cell line HFL1 was cultured in F12 medium with 10% fetal bovine serum. The cells were divided into control group, TGFβ1 (10 μg/L) stimulation group, and minoxidil (5 μmol/L) intervention group. The cells in control group were treated with the equivalent volume of medium. The RNA and protein were collected after 48 h. The mRNA levels of PLOD2, α-SMA and COLⅠ were detected by RT-qPCR. The protein levels of LH2, total Smad3, phosphorylated Smad3, α-SMA, COLⅠ and COL Ⅳ were determined by Western blot. Hydroxylysylpyridinoline (HP) content was detected by ELISA. RESULTS: After stimulation with TGFβ1, the mRNA expression of PLOD2, α-SMA and COLⅠ was increased (P<0.01), and the protein levels of LH2, p-Smad3, α-SMA, COLⅠ and COL Ⅳ were also up-regulated, but the total Smad3 protein did not change. Treatment with minoxidil decreased the levels of above indexes (P<0.01). Compared with control group, stimulation with TGFβ1 increased the content of HP. However, treatment with minoxidil decreased the synthesis of HP (P<0.05). CONCLUTION: Activation of TGFβ1/Samd3 signaling pathway enhances LH2 expression. Minoxidil inhibits the TGFβ1/Samd3 signaling transduction, thereby reducing the expression of LH2 and the synthesis of hydroxylysyl collagen pyridine chain, and reducing pulmonary fibrosis.