To investigate the phenotypic changes of the expression level of regulatory B cells and related molecules during the continuous infection of Echinococcus granulosus (E. granulosus) in mice and its relationship with E. granulosus infection and its immune effect. Experimental group mice were inoculated with protoscoleces suspension via intraperitoneally injection to prepare a mouse model of E. granulosus infection. Flow cytometry was used to detect the expression of regulatory B cells CD1dhiCD5+CD19hi cells and CD1dhiCD5+CD19hi IL-10+ cells in spleen and peripheral blood of mice. The expressions of IL-10 and TGF-β1 in mouse serum were detected via ELISA. The liver pathological changes in mice were observed by H&E staining; Moreover, the expressions and distribution of IL-10 and TGF-β1 in mice liver were measured through immunohistochemistry. The ELISA test results showed no significant changes in serum IL-10 and TGF-β1 levels in early infected mice. However, at the middle and late stages of infection, the levels of IL-10 and TGF-β1 in the serum of mice increased significantly (P < 0.05). The proportion of CD1dhiCD5+CD19hiBreg cells and the proportion of CD1dhiCD5+CD19hiIL-10+Breg cells in the spleen of mice infected with E. granulosus were increased at 90 days after infection, which indicating that Breg cells proliferated in the late stage of infection. CD1dhiCD5+CD19hi regulatory B cells may be one of the causes of immunosuppression of E. granulosus infection. It is speculated that Bregs inhibitory effect may play a role by regulating the expression of cytokines and inducing the secretion of inhibitory cytokines IL-10 and TGF-β1.
Keywords: Echinococcosis; IL-10; Regulatory B cell; TGF-β1.