MMP9 and congenital rubella syndrome: Whereas patients with neutrophil-dominated CRS can promote EMT via the IFN-γ pathway (103, 104); In addition, hypoxia-inducible factor-1α, which can induce EMT (105) has also been positively correlated with the number of neutrophils (100) and one of the primary mechanisms of pathological tissue remodeling in CRS is the imbalance between MMP and TIMP (7), where MMP-9 mainly degrades the gelatin, proteoglycan and elastin, a key factor in remodeling, whereas there is an association found between MMP-9 and neutrophils (106), which is an important source of MMP-9 (107).