IL4 and renal fibrosis: It is reported that IL-4 and IL-13 can synergize with high glucose to promote the expression of TGF-β1, FN, and collagen I in cultured HK-2 cells, indicating that the secretion of Th2 cytokines (IL-4 and IL-13) and the upregulated expression of TGF-β1 are key factors in the development of renal fibrosis [39].