title: Expression of muscarinic receptors by human macrophages.
abstract: Macrophages increase in number and are highly activated in chronic obstructive pulmonary disease (COPD). Muscarinic receptor antagonists inhibit acetylcholine-stimulated release of neutrophilic chemoattractants, suggesting that acetylcholine may regulate macrophage responses. Therefore, expression and function of components of the non-neuronal cholinergic system in monocyte-macrophage cells was investigated. RNA was isolated from monocytes, monocyte-derived macrophages (MDMs), lung and alveolar macrophages from nonsmokers, smokers and COPD patients, and expression of the high-affinity choline transporter, choline acetyltransferase, vesicular acetylcholine transporter and muscarinic receptors (M(1)-M(5)) ascertained using real-time PCR. M(2) and M(3) receptor expression was confirmed using immunocytochemistry. Release of interleukin (IL)-8, IL-6 and leukotriene (LT)B(4) were measured by ELISA or EIA. All monocyte-macrophage cells expressed mRNA for components of the non-neuronal cholinergic system. Lung macrophages expressed significantly more M(1) mRNA compared with monocytes, and both lung macrophages and alveolar macrophages expressed the highest levels of M(3) mRNA. Expression of M(2) and M(3) protein was confirmed in MDMs and lung macrophages. Carbachol stimulated release of LTB(4) from lung macrophages (buffer 222.3 ± 75.1 versus carbachol 1,118 ± 622.4 pg · mL(-1); n = 15, p<0.05) but not IL-6 or IL-8. LTB(4) release was attenuated by the M(3) antagonist, 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; half maximal effective concentration 5.2 ± 2.2 nM; n = 9). Stimulation of macrophage M(3) receptors promotes release of LTB(4), suggesting that anti-muscarinic agents may be anti-inflammatory.
authors: Airways Disease, National Heart and Lung Institute, Imperial College London, Dovehouse St, London SW3 6LY, UK.
authors: A
authors: A
authors: Koarai
authors: S L
authors: SL
authors: Traves
authors: P S
authors: PS
authors: Fenwick
authors: S M
authors: SM
authors: Brown
authors: K K
authors: KK
authors: Chana
authors: R E K
authors: RE
authors: Russell
authors: A G
authors: AG
authors: Nicholson
authors: P J
authors: PJ
authors: Barnes
authors: L E
authors: LE
authors: Donnelly
mesh_terms: D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000096:biosynthesis; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000096:biosynthesis; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism; D012313:RNA / Q000032:analysis; D011976:Receptors, Muscarinic / Q000096:biosynthesis*; D012907:Smoking / Q000378:metabolism; D050494:Vesicular Acetylcholine Transport Proteins / Q000096:biosynthesis
chemical_list: C508606:CXCL8 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; D026901:Membrane Transport Proteins; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010880:Piperidines; D011976:Receptors, Muscarinic; D050494:Vesicular Acetylcholine Transport Proteins; C065637:choline transporter; D007975:Leukotriene B4; D012313:RNA; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D002217:Carbachol; D002795:Choline O-Acetyltransferase