Objective: To study the preventive effects of soluble egg antigen (SEA) of Schistosomia japonicum on atherosclerosis in ApoE-/- mice and its immune modulatory mechanisms.
Methods: ApoE-/- mice were divided into an Experimental Group One and an Experimental Group Two. The mice in the Experimental Group One dividing into a prevention and a control subgroups were fed with high fat diet since the first week, the mice in the former subgroup were injected intraperitoneally with SEA while those in the latter one were injected with phosphate buffered saline (PBS) with 1 week interval for 4 times. The mice in the Experimental Group Two were fed with high fat diet for 14 weeks, and then they were divided into a treatment and a control subgroups, which were injected with SEA and PBS, respectively, since the 14th week with 1 week interval for 4 times. All the mice were killed in the 22nd week, and the atherosclerosis development and the change of levels of cytokines and CD4+CD25+ FoxP3+T cells in mice were observed.
Results: Immunization with SEA led to a significant reduction in the levels of cholesterol, TNF-alpha, and IL-10 in all the ApoE-/- mice. The atherosclerosis plaque area of aorta of ApoE-/- mice in the prevention subgroup reduced obviously, while there was no significant change in the treatment subgroup. In the 22nd week, the proportion of CD4+CD25+ FoxP3+T cells population in CD4+ T cells was (4.4 +/- 0.9)% in the prevention subgroup and there was a significant difference compared with that of the control subgroup [(2.6 +/- 0.3)%] (P < 0.05). However, the change of the proportion in the treatment subgroup showed no statistic significance (P > 0.05).
Conclusion: The preventive injection of SEA in ApoE-/- module mice has the effect of anti-atherosclerosis by increasing the proportion of Treg cells together with the inhibition of inflammatory cytokines at the beginning of disease.