TSLP and viral infectious disease: Beside TH2 cells, group 2 innate lymphoid cells (ILC2s) play a crucial role in mediating the type 2 immune response through production of IL-5 and IL-13 when activated by alarmins IL-25, IL-33 and thymic stromal lymphopoietin (TSLP) in response to epithelial cells damage induced by viral infections or allergens (Figure 2) (38).