IL13 and allergic asthma: In murine allergic asthma, CHI3L3 is highly expressed, correlated to levels of IL-4 and IL-13 [54], binds to carbohydrates e.g. heparin/heparan sulfate proteoglycan; which are major contributors of pulmonary fibrosis (by stimulating TGF-β signaling in fibroblasts) [55].