The study on immunological protection induced by Th1 and Th2 cytokines in mice against Schistosoma japonicum

Abstract

Objective To explore the immunologically protective effects of Th1 and Th2 cytokines in mice against Schistosoma japonicum infection.Methods 48 C57BL/6 mice were divided into four groups randomly,including interleukin (IL)-4,IL-12,thymic stromal lymphopoietin (TSLP) and saline group.In each group,each mouse was given cytokine intraperitoneally three times per week for 8 weeks continuously.The dosages were IL-4 group 200 ng each mouse,IL-12 group 200 ng each mouse,TSLP group 200 ng each mouse,and normal saline group 200 μl each mouse.Two weeks after administration,each mouse was infected with 40±2 cercariae percutaneously.Three and six weeks after infection,mice were sacrificed,and the number of worms and eggs in liver were calculated.Dynamic changes of IL-5,IL-10,interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in serum of mice in different groups were detected by suspension array technology.Pathological changes of live and spleen in the mice were detected.Results Eight weeks after intraperitoneal injections of cytokines,levels of Th2 cytokines IL-5 and IL-10 in mice of IL-4 group were 161.97 and 65.47 μg/ml,which of TSLP group were 132.72 and 77.18 μg/ml,which of IL-12 group were 87.15 and 12.29 μg/ml,which of saline group were 188.92 and 167.52 μg/ml.Levels of Th2 cytokines in mice of IL-4 and TSLP groups were higher than that of IL-12 group,but lower than that of normal saline group.Levels of IFN-γ and TNF-α in the mice of IL-12 group were 165.7 and 23.64 μg/ml,which were higher than that of other groups.The worm burden of IL-4,IL-12,TSLP and saline group were(9.50±4.51),(12.83±2.32),(6.75±2.87),(9.80±3.03)respectively three weeks after infection.The worm burdens of each group were (18.83±5.91),(24.80±9.42),(21.67±3.67),(17.67±6.74),and eggs per gram of liver were(58 286.98±25 351.60),(80 460.18±35 542.66),(54 579.56±16 399.21),(41 094.92±25 598.27) respectively six weeks after infection.There were no significant differences among four groups on worm and egg burden in mice at three and six weeks after infection with Schistosomajaponicum.Three weeks after infection,splenic indexes of each group were (0.010±0.002),(0.011±0.002),(0.009±0.001) and (0.007±0.001).Compared with saline group,splenic indexes of cytokine injection groups were significantly higher than that of normal saline group (t=3.158,5.076,6.204,P＜0.05).Six weeks after infection,liver granuloma areas in the mice of cytokine injection groups were (125 023.51± 44 403.62),(83 238.18±27 088.95),(113 661.30±46 049.24) and (146 769.60±50 096.53) μm2.Liver granuloma areas in the mice of IL-12 and TSLP groups were significantly less than that of normal saline group (t=6.483,2.283,P＜0.05),and IL-12 group was the smallest.Conclusion Th1 or Th2 cytokines had no sig nificant effect on worm and egg reduction rates,but had a protective effect on pathological changes in the liver.The protective effect of Th1 cytokine was the most significant. Key words: Schistosoma japonicum ; Th1 and Th2 ; Cytokine ; Protection against infection