The effects of a novel macrolide glasmacinal (EP395) on alveolar macrophage phenotype and phagocytosis in COPD

Macrolides such as azithromycin possess anti-inflammatory and immune-modulating effects including increased uptake of bacteria by alveolar macrophages (AM). Clinical studies have shown macrolides reduce exacerbation frequency in COPD, but antimicrobial resistance from long-term use raises concerns. Glasmacinal (EP395) is a first-in-class non-antibacterial macrolide agent with anti-inflammatory activity that is being developed as a potential treatment to reduce exacerbations of COPD. We aimed to further understand the immunomodulatory effects of EP395 on AMs from COPD patients. AMs from COPD patients (N=6) and smoking controls (N=6) were treated with EP395, azithromycin (12.5-50 µM) or budesonide (0.1-1 µM) for 6 and 24 h or for 2 h prior to 24 h stimulation with LPS (1 µg/ml). Gene expression of CD206, CD163, MERTK, IL-10, CD80, CD86 and HLA-DR were assessed by RT-PCR. CXCL8 production was assessed by ELISA. AMs were also treated for 24 h with EP395 (50 µM), azithromycin (50 µM), or budesonide (1 µM) for 24 h prior to 3 h exposure to pHrodo-labelled NTHi. Phagocytosis of NTHi was determined by flow cytometry. EP395 and azithromycin significantly increased gene expression of CD86 and IL-10 (both basal expression and after exposure to LPS), and decreased basal production of CXCL8. EP395 and azithromycin significantly increased phagocytosis of NTHi in alveolar macrophages, whereas budesonide had no effect. We show that the novel macrolide EP395 alters alveolar macrophage phenotype and increases phagocytosis of NTHi. This offers mechanistic understanding of the immunomodulatory benefits of EP395.