COPD treatment: real life and experimental effects on peripheral NK cells, their receptors expression and their IFN-γ secretion

A role in pulmonary immunity has been ascribed to Natural Killer (NK) cells and several in vitro studies have shown a corticosteroid-induced inhibition of NK cells mediated cytotoxicity. Several clinical trials on chronic obstructive pulmonary disease (COPD) have suggested a relationship between COPD treatment and occurrence of respiratory infections. Aims of our study were to investigate if real life COPD treatment affects peripheral blood NK cells total count and their receptors expression and to assess if different doses of formoterol and budesonide, administered alone or in combination, are able to modulate the surface expression of activating (NKp30, NKp44, NKp46 and NKG2D) and inhibitory (KIR2DL2/L3, KIR3DL1 and NKG2A) receptors on peripheral blood NK cells of COPD patients. Moreover, we evaluated the potential effect of treatment with budesonide and/or formoterol on IFN-γ secretion in vitro. NK cells were isolated from peripheral blood of 7 healthy volunteers, 9 chronic bronchitis (CB) and 11 COPD patients. Total NK cells count and activating and inhibitory receptors expression were evaluated. NK cells were cultured for 20h in 96-well plates with IL-2 (100IU/ml)+IL-12 (2.5ng/ml), with or without budesonide (Bud; 1 and 0.01μM) and formoterol (For; 30 and 0.3nM) alone or in combination. Cells were analyzed by flow cytometry and IFN-γ was measured in cell supernatants by ELISA test. No difference between real life treated COPD, CB and healthy subjects was found concerning NK total count and NK cell receptors expression. When cells were stimulated over night with cytokines and treated with drugs, only NKG2D receptor was modulated. Its expression was significantly downregulated by budesonide alone and in combination with formoterol in COPD patients. IFN-γ production induced by stimulation with IL-2+IL-12 was decreased in a highly significant way (p<0.01) by all treatments in all groups. Even if in vitro experiments with budesonide, alone or in combination with formoterol, showed a modulation of NKG2D receptor expression and IFN-γ production, our ex vivo results show that real life LABA and ICS treatment does not influence peripheral NK cells count and their receptors phenotype.