IL13 and asthma: As to asthma, in human and murine models, IL-19 exacerbates the disease by a positive-feedback on Th2 cells and M2 macrophage via upregulation of such Th2 cytokines as IL-4, IL-5, IL-10, and IL-13 (18, 19, 32, 36), whereas IL-19 also promotes M1 macrophage by upregulation of such Th1 cytokines as IL-6 and TNF-α (37).