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

Area of Science:

• Immunology
• Pulmonology
• Genetics

Background:

• Human blood monocytes are classified into CD14+CD16- (classical), CD14+CD16+ (intermediate), and CD14-CD16+ (non-classical) subsets.
• These monocyte subsets possess distinct functions and are implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD).
• Alpha-1 antitrypsin (AAT) deficiency (PiZZ) is a genetic condition associated with COPD and reduced levels of the anti-inflammatory protein AAT.

Purpose of the Study:

• To investigate and compare blood monocyte subsets in clinically stable COPD patients with AAT deficiency (PiZZ) and normal AAT (PiMM).
• To analyze the impact of lipopolysaccharide (LPS) stimulation on monocyte subset distribution in these patient groups.

Main Methods:

• Peripheral whole blood from PiZZ and PiMM COPD patients was collected and incubated with LPS or placebo.
• Flow cytometry analysis was performed using HLA-DR, CD14, and CD16 staining to profile monocyte subsets.
• Monocyte subsets were quantified based on their expression of CD14, CD16, and HLA-DR.

Main Results:

• No significant differences were observed in HLA-DR+ monocyte subsets between PiZZ and PiMM COPD patients, or healthy controls.
• The intermediate monocyte subset (CD14+CD16+) was significantly lower in PiZZ patients and nearly absent after LPS treatment.
• The non-classical monocyte subset (CD14-CD16+) was markedly reduced in PiZZ patients, irrespective of LPS stimulation.

Conclusions:

• Clinically stable COPD patients with AAT deficiency (PiZZ) exhibit distinct alterations in blood monocyte subsets, notably a reduction in intermediate and non-classical monocytes.
• These monocyte subset alterations, coupled with diminished AAT levels, may play a crucial role in the early onset of emphysema in PiZZ individuals.
• Monocyte profiling offers clinical insights into the pathogenesis of COPD associated with AAT deficiency.