CXCR5+ST2+memory Th2 cell reduced maturation and fecundity of Nippostrongylus brasiliensis through increase of expression of Major Basic Protein in eosinophils

Abstract Once mice experience the infection of helminth, the mice acquired resistance to the helminth. We have studied about memory responses against Nippostrongylus brasiliensis (Nb) in mice. Nb penetrates into skin, passes through the lungs and finally reaches to the gut. It has been reported that IL-33 contributes to the immune responses against re-infection of helminth. However, the IL-33-dependent immunity to Nb has not been fully defined. In this study, we identified subsets of memory Th2 (mTh2) cells; CXCR5+ST2+CD44hiTh2 cells and ST2−CD44hiTh2 cells producing IL-4 and IL-13, and increasing accumulation of eosinophils in the lungs in helminth infection. CXCR5+ST2+mTh2 cells rather than ST2− mTh2 cells strongly expressed IL-5 and increased the expression of Major Basic Protein (MBP) in eosinophils in the lungs, which is important for reduction of maturation and fecundity of Nb in the intestine. Notably, we also found ST2+Treg cells but not ST2− Treg cells can suppress the ST2+mTh2 cell-mediated reduction of fecundity of Nb. Taken together, these findings indicate that we identified a mechanism against helminth elicited by a subpopulation of IL-5-producing Th2 cells through the accumulation of eosinophils strongly expressing MBP in the lungs. This would be helpful to establish the drugs and/or vaccination against helminth,