title: Endomorphins delay constitutive apoptosis and alter the innate host defense functions of neutrophils.
abstract: Recent studies have shown that opioid peptides are released from cells of the immune system during inflammation and stress, and are associated with altered immune responses. Moreover, concentrations of opioid peptides are increased in peripheral blood and at the sites of inflammatory reactions. The aim of this study was to evaluate immunological effects of opioid peptides endomorphins 1 and 2 on constitutive apoptosis, superoxide anion production, hydrogen peroxide production, adhesion, phagocytosis, and chemotaxis of neutrophils. Neutrophils were isolated by peritoneal lavage from rats. Endomorphins 1 and 2 significantly delayed constitutive neutrophil apoptosis. The delay of neutrophil apoptosis was markedly attenuated by LY294002, a phosphoinositide 3-kinase inhibitor. Moreover, endomorphins 1 and 2 activated the phosphoinositide 3-kinase pathway as determined by phosphorylation of BAD. In contrast, endomorphins 1 and 2 blocked the production of superoxide anion and hydrogen peroxide by PMA-stimulated neutrophils. In addition, endomorphins 1 and 2 inhibited neutrophil adhesion to fibronectin. Moreover, endomorphins 1 and 2 potentiated neutrophil chemotaxis toward zymosan-activated serum and IL-8, respectively. However, endomorphins 1 and 2 did not alter phagocytosis of Escherichia coli by neutrophils. These results suggest that endomorphins 1 and 2 may act to delay neutrophil apoptosis and alter the natural immune functions of neutrophils.
authors.affiliation: Department of Pharmacology, Osaka Dental University, 8-1 Kuzuhahanazono-cho, Hirakata, Osaka 573-1121, Japan. aazuma@cc.osaka-dent.ac.jp
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Azuma
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ohura
authors.forename: Pao-Li
authors.initials: PL
authors.lastname: Wang
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Shinohara
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D002634:Chemotaxis, Leukocyte; D006861:Hydrogen Peroxide / Q000378:metabolism; D016209:Interleukin-8 / Q000276:immunology; D008297:Male; D009504:Neutrophils / Q000276:immunology*; D009842:Oligopeptides / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D015054:Zymosan / Q000276:immunology
chemical_list: D016209:Interleukin-8; D009842:Oligopeptides; C105293:endomorphin 1; D013481:Superoxides; C105294:endomorphin 2; D015054:Zymosan; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases