Wang et al. performed an in vitro study and found that rhinoviral infection enhanced the gene and protein expressions of MMP-2, MMP-9, and VEGF in nasal polyp fibroblasts, derived from polypoidal nasal tissue, implying the possible role of viruses in exacerbation of CRSwNP (41). Here, MMP9 is linked to chronic rhinosinusitis with nasal polyps.