Study On The Effects Of TSG-6 On The Apoptosis Of Keloid Fibroblasts And NF-κB Signaling

Background Keloids are common benign collagenous tumors,characterized as an over-exuberant healing response resulting in proliferation of dermal fibroblasts and a disproportionate extracellular matrix（ECM）accumulation.Basal Nuclear factor-kappa B（NF-κB）activity was constitutively elevated in keloid fibroblasts,indicating that this pathway is involved in keloid pathogenesis.NF-κB pathway may play an important part in keloid pathogenesis.Our previous investigation has demonstrated that TNF-stimulated gene 6 protein（TSG-6）could play a key role in inhibition of keloid formation.However,only a few studies have revealed a direct interaction between TSG-6 and NF-κB in keloid formation.Objective To investigate the effects of tumor necrosis factor-stimulated gene 6（TSG-6）on apoptosis of keloid fibroblasts and detect NF-κB signaling pathway.Methods Fibroblasts derived from keloid and normal skin were cultured with different concentration of rhTSG-6（0 ng/m L,50 ng/m L,100 ng/m L,200ng/m L and 400 ng/m L）in vitro.MTT was used to detect cell proliferation,and IC₅₀ value of rhTSG-6 was calculated by MTT.Cell apoptosis and cell cycle was determined by flow cytometry.The expression levels of NF-κB,IκBα,p-IκBα,cleaved-Caspase3 and Caspase8 were determined by Western blot,respectively.NF-κB activity was assessed by Electrophonetic mobility shift assay（EMSA）.ResultsrhTSG-6 showed proliferation inhibition effect against KFs and IC₅₀ value of rhTSG-6 to KFs was nearly 300ng/m L.After treated with rhTSG-6 at the concentration of 300ng/m L for 48 h,the rate of apoptosis of KFs was increased（p <0.05）.The expression level of cleaved-Caspase3 and Caspase8 were significantly increased in rhTSG-6 treated group.But at the same time,rhTSG-6 has no significant effects on NFs.In the other hand,the whole p-IκBα level was significantly reduced upon rhTSG-6 treatment with marked increase in IκBα levels.NF-κB activity was decreased significantly compared to the control group.Conclusions In summary,these data suggest that TSG-6 may induce cell apoptosis in KFs via inhibiting the activation of NF-κB pathway.