MMP9 and idiopathic pulmonary fibrosis: Numerous studies have demonstrated that NAC inhibits the production of different inflammatory mediators such as tumour necrosis factor alpha (TFNα), interleukin-8 (IL-8) and matrix metalloproteinase-9 (MMP-9) in epithelial cells, macrophages, and lymphocytes from patients with IPF (Watchorn et al., 1998; Parmentier et al., 1999; Cu et al., 2009; Radomska-Leśniewska et al., 2010).