Quantitative estimation of phenotypic plasticity of macrophages in vitro: the first test in healthy non-smokers, smokers persons and patients with chronic obstructive pulmonary disease

Abstract

Immunity disorders underlie many diseases, including chronic obstructive pulmonary disease (COPD), cancer,
etc. Evaluating the macrophage phenotypic plasticity (PhP) may provide insight into disease pathogenesis. However
simple and reliable methods for such evaluation have not been available so far. In this study, we were focused
on 1) developing a method for quantification of macrophage phenotypic plasticity (PhP-assay), and 2) using the
PhP-assay for evaluation of macrophage plasticity in normal conditions, under the action of a pathogenic factor
(smoking), and in a disease (COPD). The PhP-assay includes four steps: 1) alveolar macrophage isolation and
culture; 2) macrophage reprogramming; 3) macrophage stimulation; and 4) determination of macrophage phenotype
and PhP. The following results were obtained. 1) Smoking shifts the macrophage functional cytokine phenotype
towards M2, increases the macrophage capability for changing towards the proinflammatory M1 phenotype
(PhP-M1) and reduces the macrophage capability for changing towards the anti-inflammatory M2 phenotype
(PhP-M2); 2) The functional cytokine phenotype of macrophages from patients with COPD, as distinct from
healthy non-smokers, successively changes from M2 with increased PhP-M1 and decreased PhP-M2 in stage 1
COPD to M1 with increased PhP-M2 in stage 3 COPD. Results of the PhP-assay showed that the mechanism underlying
the transformation of compensatory M2 macrophages of healthy smokers and patients with early COPD
into pathogenetic M1s in late COPD is related with disturbed plasticity of the M2 phenotype, and suggested that
the risk of lung cancer in stage 3 COPD is associated with increased M2 plasticity of the alveolar macrophage M1
phenotype.