N-acetylcysteine inhibits TNF-alpha, sTNFR, and TGF-beta1 release by alveolar macrophages in idiopathic pulmonary fibrosis in vitro. 
BACKGROUND: N-acetylcysteine (NAC) can act as an antioxidant. NAC slows the rate  of decline of lung function in idiopathic pulmonary fibrosis (IPF) patients concurrently treated with prednisone and azathioprine. OBJECTIVE: In this study we investigated the effect of NAC on the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12 (p70), IL-18, transforming growth factor (TGF)-beta1, and the soluble TNF receptors (sTNFR1 and sTNFR2) by alveolar macrophages (AM) in IPF patients. DESIGN: AMs were harvested by bronchoalveolar lavage (BAL) from 16 IPF patients and were cultured for 24 h with RPMI medium alone, or with lipopolysaccharide (LPS) (100 ng/ml), in the presence or absence of NAC at various concentrations. RESULTS: NAC suppressed the production of TNF-alpha, its soluble receptors, and TGF-beta1 by AMs in a dose-dependent manner. At the highest concentration of NAC  (10 mM), the spontaneous or LPS-stimulated production ofTNF-alpha, sTNFR1, sTNFR2, and TGF-beta1 were significantly reduced. The LPS-stimulated IL-1beta production was also suppressed by 10 mM NAC. CONCLUSIONS: NAC has the potential to down-regulate the production of TNF-alpha and their soluble receptors, as well as TGF-beta1 and LPS-stimulated IL-1beta, by AM in IPF in vitro. NAC may have anti-inflammatory and anti-fibrotic effects.