The role and mechanism of TNFα-induced protein 3 (A20) in phenotypic transformation of human dermal fibroblasts to myofibroblasts

Abstract

Objective To investigate the role and mechanism of A20 protein in the phenotypic transformation of human dermal fibroblasts (Fb) to myofibroblasts (MFb). Methods Primary human normal skin Fb (NFb) and scar skin Fb (HFb) were isolated and cultured by enzymatic digestion. The cells were used in logarithmic growth phase at 3-5 passages, and Fb was stimulated by transforming growth factor-β (TGF-β) to mimic the Fb to MFb transformation process. Cell transfection was conducted to knock out the expression of A20 in Fb, and quantitative real-time polymerase chain reaction (PCR) test, protein immunoblotting test were conducted to detect A20, type Ⅰ collagen (Col Ⅰ), type Ⅲ collagen (Col Ⅲ) and α-smooth muscle (α-SMA), and p-Smad 2 expression in Fb. Results Compared with normal skin Fb, A20 was down-regulated in pathological scar Fb (P<0.05). After TGF-β stimulated, A20 expression was significantly decreased (P<0.05), while the expression of fibrosis associated molecules such as Col Ⅰ, Col Ⅲ and α-SMA and p-Smad 2 was significantly increased (P<0.05) in Fb. Knockout of A20 in Fb further promoted TGF-β induced the expression of fibrosis associated molecules such as Col Ⅰ, Col Ⅲ and α-SMA and p-Smad 2 (P<0.05). Conclusions A20 protein is involved in the process of human dermal Fb to MFb phenotype transformation, and A20 negatively regulates the transformation effect mediated by TGF-β by inhibiting the activation of Smad signaling pathway. Key words: Fibroblasts; Myofibroblasts; Transforming growth factor beta; Tumor necrosis factor alpha-induced protein 3