Reduced pulmonary CFTR expression is a hallmark of the HF lung
The accumulation of non-alveolar classically-activated macrophages (CD80+ SiglecF-) associated with markedly higher TNF-α protein levels in HF compared to sham lungs (Fig. 3a ). Since TNF-α potently reduces CFTR surface expression in different cell types [5, 29], we determined cell surface-specific CFTR expression in the lung by performing a flow cytometry-based CFTR staining approach with an antibody targeting membrane-associated, mature CFTR protein [30] (Supplemental Table 1 ). The overall number of surface-CFTR+ cells was significantly reduced in HF lungs (Fig. 3b, c ), which coincided with significantly lower expression levels of membrane-bound CFTR assessed by Western blotting (Fig. 3d ).