IL4 and pulmonary fibrosis: Moreover, IL-25 overexpression is associated with perivascular fibrosis in an IL-4 and IL-13 dependent manner (169) and IL-25-/- animals are protected from S. Mansoni and bleomycin-induced lung fibrosis due to ILC2 related IL-13 production (166), emphasizing its upstream role in type 2 immunity mediated fibrosis.