IL-4Ralpha responsive CD4+CD25−CD103+FoxP3− cells control Schistosoma mansoni egg-induced inflammation by secreted IL-10

IL-4Ralpha signalling drives Th2-type responses that mediate resistance to parasitic helminth infections. We generated a novel mouse model lacking IL-4Ralpha expression specifically on all T cells (iLckcreIl4ra−/lox) to investigate IL-4Ralpha-dependent T cell responses during Schistosoma mansoni egg-driven inflammation. These mice showed higher mortality during acute schistosomiasis compared with Il4ra−/lox controls and previously established CD4+ T cell specific IL-4Ralpha deficient mice (LckcreIl4ra−/lox). iLckcreIl4ra−/lox mice developed a liver restricted pathology associated with drastic reductions of both Th2/type 2 responses and alternative macrophage activation within the granulomas. Additionally, iLckcreIl4ra−/lox mice had (i) increased FoxP3+ Treg cell responses in the granulomas, which was explained by IL-4 mediated inhibition of FoxP3 induction, and (ii) reduction of antigen-specific production of IL-10 by CD4+CD103+FoxP3− cells. In a footpad model of S. mansoni egg-induced inflammation with subsequent IL-10 neutralisation and adoptive cell transfer experiments we found evidence that the increased inflammation in iLckcreIl4ra−/lox mice was due to the impaired development of IL-10-secreting CD4+CD25−CD103+FoxP3− cells. Together, these data demonstrate that IL-4Ralpha responsiveness by T cells promote IL-10-secreting CD4+CD25−CD103+FoxP3− cells and alternatively activated macrophages, which act in concert to control egg-induced inflammation.