Effect of capsaicin on monocyte differentiation in patients with chronic obstructive pulmonary disease

Abstract

Introduction. It is known that monocytes and derived macrophages play an important role in the development of chronic obstructive pulmonary disease (COPD). Previously, we found that cigarette smoke-sensitive TRPV1 channels have higher expression on monocytes and macrophages of COPD patients.Aim. To investigate the effect of chronic TRPV1 activation on the differentiation of monocytes into macrophages in vitro.Materials and methods. The study included 11 patients with COPD and 7 healthy non-smoking volunteers (control). Monocytes were obtained from peripheral blood mononuclear cells by plastic adhesion. Cells were cultured for 10 days in the presence of granulocytemacrophage colony-stimulating factor (GM-CSF) or GM-CSF and the TRPV1 agonist capsaicin. On the 11th day, the cells were stimulated with lipopolysaccharides (LPS). Expression of the genes encoding the transcription factors STAT1, STAT6, IRF3, JUN, MAF, RELA, cytokines IL1B, IL6, IL8, and three reference genes B2M, RACK1 and HPRT1 was assessed by quantitative PCR with reverse transcription.Results. Initially, macrophages of COPD patients differentiated in the presence of GM-CSF had higher expression of STAT1 (2.98-fold, p=0.03) and JUN (1.6-fold, p=0.02). LPS stimulation was accompanied by upregulation of IRF3 (4.3-fold, p=0.04), RELA (1.3-fold, p=0.05) and interleukin genes. Under the action of LPS COPD macrophages had 3.2-fold higher expression of IRF3 as compared to the control (p=0.05). Capsaicin also caused upregulation of IRF3 in cells from COPD patients, thus the expression of this factor became 3.2-fold higher than in the control group (p=0.03). Differentiation with capsaicin sensitized macrophages to LPS. Under these conditions JUN expression increased both in COPD patients (1.8-fold, p=0.01) and in the control group (2.2-fold, p=0.02) as compared with cells differentiated with GM-CSF alone.Conclusion. The obtained results indicate that in resting state macrophages from COPD patients are mostly characterized by a proinflammatory M1 polarization. LPS probably leads to an additional polarization towards M2b phenotype, when compared with the control, as indicated by an increase in the level of IRF3 transcripts. Capsaicin also promotes M2b polarization of COPD macrophages and may enhance the inflammatory response of cells to LPS.