Effects of EP4 and EP2 antagonist on the differentiation of Treg/Th17 cells in mice of collagen induced arthritis / 中华风湿病学杂志

ABSTRACT

Objective To study the effects of EP4 and EP2 antagonists on the differentiation of Treg/ Th17 cells and disease progression in mice of collagen-induced arthritis (CIA) model.Methods DBA/1 mice wereimmunized subcutaneously twice at the root of the tail with type Ⅱ collagen emulsified in Freund's complete adjuvant.EP2 and EP4 antagonist therapies were intraperitoneally administrated for 14 consecutive days after the second immunization.Clinical signs,histological manifestation,serum interleukin (IL)-17 and quantity of CD4+CD25+Foxp3+ Treg cells were determined.ANOVA and t-test were used for statistical analysis.Results Clinical signs of the disease appeared on day 27 and peaked on day 35 after the first immunization.The quantity of CD4+CD25+Foxp3+ Treg cells in spleens [(1.67±0.15)％] and draining inguinal lymph nodes [(3.30±0.36)％] isolated from CIA mice were significantly lower than those of normal DBA/1 mice [(2.77±0.45)％ and (4.73 ±0.45)％ respectively,P＜0.05].Serum IL-17 level of CIA mice [(27±7) pg/ml] was significantly higher than that of normal DBA/1 mice [(14±4) pg/ml,P＜0.05].Intra-peritoneal injection of EP4 but not EP2 antagonist to CIA mice decreased paw edema and swelling,and alleviated the histological manifestations (1.8±1.0 vs 3.5±0.6,P＜0.05) on day 35 after the first immunization.The percentages of CD4+CD25+Foxp3+ Treg cells in both inguinal lymph nodes [(4.20±0.32)％] and spleens [(2.63±0.40)％] were significantly higher in EP4 antagonist-treated but not EP2 antagonist-treated CIA mice compared with CIA mice group [(3.30±0.36)％ and (1.67±0.15)％ respectively,P＜0.05].The level of serum IL-17 was significantly lower in EP4 antagonist-treated [(15±7) pg/ml] but not EP2 antagonist-treated CIA mice compared with CIA mice group [(27±7) pg/ml,P＜0.05].Conclusion EP4 antagonist therapy alleviates clinical symptoms of CIA,improves the histological manifestations,decreases the serum IL-17 level and increases the percentages of CD4+CD25+Foxp3+ Treg cells in both spleens and draining inguinal lymph nodes,so targeting EP4 receptor may be a new possible therapeutic possibility in the prevention and treatment of rheumatoid arthritis.