N-acetylcysteine and azithromycin affect the innate immune response in cystic fibrosis bronchial epithelial cells in vitro.

Background and objective. We have previously reported that N-acetylcysteine (NAC), ambroxol and azithromycin (AZM) (partially) correct the chloride efflux dysfunction in cystic fibrosis bronchial epithelial (CFBE) cells with the Delta F508 homozygous mutation in vitro. Methods. In the present paper, we further investigated possible immunomodulatory effects of these drugs on the regulation of the innate immune system by studying the expression of the cytosolic NOD-like receptors NLRC1 and NLRC2, and interleukin (IL)-6 production in CFBE cells. Results. Under basal conditions, PCR and Western Blot data indicate that the NLRC2 receptor has a reduced expression in CF cells as compared to non-CF (16HBE) cells, but that the NLRC1 expression is the same in both cell lines. AZM significantly upregulated NLRC1 and NLRC2 while NAC upregulated only NLRC2 receptor expression in CF cells. Reduced basal IL-6 production was found in CF cells as compared to non-CF cells. MDP (an NLRC2 agonist), NAC and AZM, but not Tri-DAP (an NLRC1 agonist), increased IL-6 production in CF cells, indicating that in CF cells IL-6 upregulation is independent of NLRC1, but involves the activation of NLRC2. Conclusion. Overall, the results indicate that NAC and AZM not only can correct the chloride efflux dysfunction but also have a weakly strengthening effect on the innate immune system.