Tachykinin activation of human alveolar macrophages in tobacco smoke and sarcoidosis: a phenotypical and functional study.

Substance P (SP) and neurokinin A (NKA), which exert bronchoconstrictor effects on human airways, are known to interact with inflammatory and immune cells, including monocyte macrophages. We have evaluated the effects of SP, NKA and the NK2 selective agonist [beta-Ala8]-NKA(4-10) on alveolar macrophages (AM) isolated from 4 healthy smokers and 4 non-smoker active pulmonary sarcoid patients. An accumulation of activated mononuclear phagocytes, as well as elevated angiotensin-converting enzyme (ACE) activity, has been evidenced in both clinical conditions. The phenotype of AMs in the studied subjects was characterized by an elevated expression of CD68+, HLA-DR+ and CD14+, CD14+ being significantly less in sarcoidosis as compared to smokers. SP, NKA and the NK2 selective agonist evoked superoxide anion (O2-) production in AMs obtained from sarcoid patients or healthy smokers. While SP acted in a non-dose-dependent manner in both conditions, NKA and [beta-Ala8]-NKA(4-10) evoked a dose-dependent respiratory burst (ED50 = 0.25 and 0.26 nM, respectively) in smokers, but not in sarcoidosis. The more marked phenotypical expression correlated well with the ability of NK2 receptors to activate AMs in smoker subjects.