Abstract: AIM: To observe the role and its possible mechanism of inflammatory cytokines of IL-1 β and TNF α which plays an important role in the etiology of MTX on RA. METHODS: The establishment of animal model of rheumatoid arthritis with collagen type II, with MTX (0.2 mg/kg/W) treatment, the rats were killed after six weeks, serum for detection of IL-1β and TNF-α; separation of knee joint synovial cells in rats (FLS) were cultured, identification,detection of LPS induced FLS in the culture supernatant of IL-1β and TNF -α, and observes the effect of MTX on the secretion of IL-1β and TNF-α of FLS; adding different doses of MTX on the FLS culture, expression by Western Blot method for detection of FLS ERK protein and phosphorylation of protein. RESULTS: Arthritis index score and joint swelling and joint pathology showed determination modeling success, isolated synovial cells by flow cytometry FLS expression of VCAM-1 was 85.5%. After modeling, CIA rat serum IL-1 β and TNF- α increased obviously, there was significant difference compared with the blank control group (P<0.05), MTX could effectively reduce the content of serum CIA in rats of IL-1 β and TNF -α (P<0.05), but failed to recover to normal.In rats with CIA FLS MTX could inhibit LPS induced secretion of IL-1 β and TNF-α. Displayed in Western Blot detection, different concentrations of MTX on ERK protein expression of FLS in CIA rats compared with the model group showed no significant difference (P>0.05). Expression of p-ERK CIA in FLS of rats was significantly higher than that in control group (P<0.01), after the treatment of MTX, low dose group had no effect on the expression of p-ERK protein, while in the medial and high dose group could reduce the p-ERK protein (P<0.05). CONCLUSION: MTX has immunosuppressive effects at the same time through the inhibition of inflammatory cytokines IL-1 β and TNF -α, it also has anti-inflammatory effect. The mechanism may be partly related to inhibition of MAPK signaling pathway in ERK phosphorylation relate.

Key words: rheumatoid arthritis, methotrexate, IL-1β, TNF-α, ERK/p-ERK