Figure 1. Ivacaftor alters the monocyte plasma membrane (PM) proteome but does not change systemic inflammation. All measurements were performed at Day 0, before initiation of ivacaftor, and on Day 7 of therapy. Patients were prescribed ivacaftor 150 mg by mouth, every 12 hours. Effects of ivacaftor on (A) sweat chloride levels. Normal,, 40 mM; borderline, 41–60 mM; abnormal (consistent with cystic fibrosis transmembrane conductance regulator [CFTR] dysfunction),. 60 mM, and (B) FEV1 (liters).(C) Flow cytometry demonstrates enrichment of monocytes (Mn, CD14 1 cells) after magnetic bead negative selection.(D) The graph depicts all 731 proteins detected by PM proteomics, with each dot representing one protein. Red dots indicate the 21 proteins that were statistically significantly changed in abundance between Day 0 and Day 7.(E) Heat map of PM proteins significantly regulated after 7 days of ivacaftor treatment. Protein levels are presented as fold changes (log 2 scale) from Day 7 to Day 0 and Day 2 to Day 0. Yellow, up-regulated; blue, down-regulated.(F) Bioinformatics analysis of the 21 proteins altered by ivacaftor identified that proteins involved in the inflammatory response and monocyte migration were altered by ivacaftor treatment much more frequently than expected on the basis of their representation in the genome. PM-associated levels for these proteins (spectral counts) and references implicating their involvement in the functional categories are provided.(G and H) Plasma IFNg and C-reactive protein (CRP) levels before and after ivacaftor therapy.(I) Peripheral blood mononuclear cells (PBMCs) were analyzed by flow cytometry to determine proportions of leukocyte subsets; CD3 1, T cells; CD19 1, B cells; CD14 1, monocytes.(J) A hypothetical model for how ivacaftor may elicit PM proteomic changes in monocytes. Model 1 proposes that exaggerated IFNg responses are produced by dysfunctional CFTR and that ivacaftor therapy attenuates IFNg responses by increasing monocyte CFTR channel activity. Model 2 proposes that changes in the lung caused by ivacaftor lead to systemic changes that affect monocyte IFNg responses. CFTR is depicted in the plasma membrane for simplicity of illustration; however, CFTR may be present in other membranes within monocytes. Dashed arrows indicate possible intermediate steps, whereas solid arrows indicate direct actions. FEV1, forced expiratory volume in 1 sec; ns, not significant.