Blood monocyte profiles in COPD patients with PiMM and PiZZ α1-antitrypsin

Human blood monocytes are divided into populations based on the differential expression of CD14 and CD16 receptors: CD14 + CD16(classical), CD14 + CD16 + (intermediate), and CD14−CD16+ (non-classical). Given their functional differences and their role in pathogenesis of chronic obstructive pulmonary disease (COPD), monocyte profiling is of clinical interest. Here we investigated blood monocyte subsets in clinically stable COPD patients with alpha1-antitrypsin (AAT) deficiency (PiZZ, n = 7) and with normal AAT variant (PiMM, n = 7). Peripheral whole blood was collected in sodium heparin tubes and incubated with LPS (from E. coli; 1 μg/ml) or placebo for 6 h at 37 °C, 5% CO2. To profile monocyte subsets we performed flow cytometry analysis based on HLA-DR and CD14/CD16 staining. HLA-DR + subsets of cells did not differ between PiZZ and PiMM COPD, and healthy controls (n = 7), used as a reference. Monocyte profiling, which express the CD14 and CD16, but not the HLA-DR (HLA-DR-) showed that intermediate monocytes subset was lowest in PiZZ group, and almost totally disappeared from blood treated with LPS. The non-classical subset was almost absent in PiZZ patients independently of LPS treatment. Recent studies demonstrate that non-classical monocytes exhibit a unique ability to protect the vascular endothelium under both homeostatic and inflammatory conditions whereas intermediate monocytes are recruited at a later stage of inflammation, and are associated with secretion of cytokines/chemokines and wound healing. Evident alterations in blood monocyte subsets together with a partial reduction of AAT levels, an important anti-inflammatory protein, can be key factors for the early manifestation of emphysema in some PiZZ AATD carriers. [Display omitted] •Human monocyte subsets-classical, intermediate and non-classical-are defined.•Monocyte subsets are phenotypically and functionally different.•Blood monocytes play an essential role in the pathogenesis of COPD.•Inherited PiZZ AAT deficiency is a genetic risk factor for the early onset COPD.•The frequency of intermediate and non-classical subsets is low in PiZZ patients.