Pharmacological CFTR correction promotes an anti-inflammatory phenotype of macrophages in the HF lung
Considering the high CFTR positivity of peripheral and pulmonary monocytes and macrophages (Supplemental Fig. 5A, 5B ), we explored the effects of pharmacological CFTR correction on macrophages in the lung. Both systemic and lung-specific Lum administration significantly increased the overall number of pulmonary macrophages (Supplemental Fig. 6A ) with larger effects after o.t. application. The treatment-associated increase of overall pulmonary macrophage counts was mainly mediated by increases of non-alveolar macrophages (Supplemental Fig. 6B ), which were more pronounced after o.t. application. In contrast to systemic administration, o.t. administered Lum markedly augmented the number of alveolar macrophages (Supplemental Fig. 6C ). To understand whether this increase in macrophages was beneficial or rather detrimental, we explored macrophage activation profiles by determining the proportion of classically- (CD80+) and alternatively- (CD206+) activated cells within the pulmonary macrophage population. The HF-associated augmentation of classically-activated macrophages was alleviated by therapeutic Lum administration irrespective of application route (Fig. 6a, d ). Likewise, therapeutic CFTR correction significantly attenuated the HF-associated increase of non-alveolar CD80+ macrophages (Fig. 6b, e ). Interestingly, o.t. treated HF lungs presented with markedly higher proportions of CD80+ alveolar macrophages (Fig. 6c, f ), suggesting an application-induced pro-inflammatory response. In contrast to CD80+macrophages, Lum induced higher proportions of alternatively-activated macrophages overall as well as alveolar and non-alveolar irrespective of treatment route (Fig. 6, Supplemental Fig. 7 andSupplemental Table 4 ). This is corroborated by increased pulmonary IL-10 mRNA expression after systemic Lum administration (Supplemental Fig. 8 ). In vitro , murine macrophages (RAW246.7 cells) presented with reduced CFTR positivity after PMA-induced activation, which was attenuated by CFTR correction with Lum (Supplemental Fig. 9 ), suggesting an interplay between CFTR surface expression and macrophage activation.