Effects of TNF-α in rheumatoid arthritis via attenuating α1 (I) collagen promoter

To explore the role of TNF-α in the peripheral blood of patients with rheumatoid arthritis (RA) and its underlying mechanism.

32 patients diagnosed with RA in our hospital from July 2016 to March 2017 were selected in the experimental group. Meanwhile, 32 normal healthy people were selected in the healthy control group and 21 patients with other autoimmune diseases in the same period were selected in the disease control group. Serum samples of the subjects in the experimental group and the control group were collected. The content of serum tumor necrosis factor-α (TNF-α) was detected by enzyme-linked immunosorbent assay (ELISA), and the correlation between TNF-α and RA activity was analyzed. We then constructed rat RA model. The effect of different doses of TNF-α on the RA progression was evaluated by measuring the foot paw thickness of both hind limbs of rats. Fibroblast-like synoviocytes (FLS) were treated with different concentrations of TNF-α cytokine in vitro. Cell counting kit-8 (CCK-8) assay was carried out to detect the cell viability after TNF-α treatment. Serum levels of VEGF (vascular endothelial growth factor) and hydroxyproline were detected. Moreover, the α1 (I) collagen overexpression recombinant was constructed and transfected into MH7A cells. The activation of α1 (I) collagen promoter was reflected by the CAT reporter gene activity.

ELISA results showed higher content of TNF-α in the peripheral blood of the experimental group than that of the control group. In the RA rat model, the foot paw thickness of the hind limbs was increased with the increase of TNF-α concentration. CCK-8 and colony formation assay demonstrated that the proliferation of MH7A cells was elevated after TNF-α treatment. Higher levels of VEGF and IL-6 secreted by FLS and decreased collagen synthesis ability of MH7A cells were found after TNF-α treatment. Transfection of the α1 (I) collagen overexpression recombinant in MH7A cells led to the reduced activity of CAT after TNF-α treatment, suggesting that the activation of α1 (I) collagen promoter was inhibited.

TNF-α participates in RA by inhibiting the activation of the promoter of α1 (I) collagen, as well as enhancing the secretion of VEGF and IL-6 in MH7A cells.