Tachykinin activation of human monocytes from patients with interstitial lung disease, healthy smokers or healthy volunteers

Three types of tachykinin receptors, NK₁, NK₂ and NK₃, have been described to preferentially interact with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) respectively. Experimental evidence indicates that SP and NKA modulate the activity of inflammatory and immune cells, including mononuclear ones, and points to their involvement in lung pathophysiology. We previously reported that NK₁ and NK₂ receptors are present on monocytes (MO) isolated from healthy donors or rheumatoid patients - a greater sensitivity to NK₂ receptor stimulation was observed in the latter condition. This study evaluated the effects of SP and NKA, as well as NK₁ and NK₂ selective agonists and antagonists, on MO obtained from healthy volunteers, healthy smokers or patients with interstitial lung diseases (e.g. sarcoidosis and idiopathic pulmonary fibrosis). Superoxide anion (O₂^-) production was chosen as a parameter of cell activation. SP and NKA dose- dependently evoked O₂^- production from MO in all the conditions evaluated, their effects being competitively antagonized by selective antagonists (CP 96 345 and MEN 10 627, respectively). When selective NK₁ and NK₂ agonists were used, [Sar ⁹Met(O₂)¹¹]SP, a selective NK₁ agonist, induced a more than doubled O₂ production in MO obtained from patients with interstitial lung diseases as compared to healthy volunteers, whereas MO isolated from healthy volunteers were more sensitive to NK₂ receptor stimulation. (C) 2000 Harcourt Publishers Ltd.