32 Mediation of pro/anti-inflammatory balance by vardenafil in mouse CF macrophages is dependent on CFTR expression

Abstract

Objectives: Having recently demonstrated that vardenafil, a phosphodiesterase type 5 inhibitor, reduces LPS-induced inflammatory responses in CF mice, we hypothesized that CF macrophages are characterized by a pro-inflammatory phenotype which can be modulated by vardenafil. We also want to study the role of CFTR in this vardenafil-induced immunomodulation of macrophages. Methods: Macrophages were purified from lung homogenates from homozygous F508del-CFTR, CFTR-/- (KO) and wild-type (WT) mice. To test the hypothesis that macrophages activity is altered in F508del-CF and KO mice, macrophages differentiation in pro-inflammatory (M1) effectors was studied after polarization with LPS and IFN-γ. Pro-inflammatory mediators TNF-α and NOS-2 were quantified by ELISA or by quantitative RT-PCR. Results: F508del-CF lung macrophages displayed an exaggerated pro-inflammatory response to M1 mediators. Both TNF-α and NOS-2 levels were more than doubled. Similar observations were made in macrophages isolated from KO mice, confirming that loss of CFTR promotes pro-inflammatory phenotype in macrophages. In F508del-CF mice, vardenafil reduced the expression of pro-inflammatory mediators by at least 50%. However, vardenafil failed to normalize TNF-α and NOS-2 expression in KO macrophages, suggesting that the presence of CFTR protein is required for immunomodulation by vardenafil. Conclusion: Taken together, our results indicate that macrophages display a pro-inflammatory profile and play a critical role in inflammatory responses in CF. Moreover, the immunomodulatory effect of vardenafil, which could thus be beneficial in CF pharmacotherapy, requires CFTR expression.