title: NO signaling in exercise training-induced anti-apoptotic effects in human neutrophils.
abstract: Short-lived neutrophils play a predominant role in innate immunity, the effects of exercise training on neutrophil survival is unclear. In this study, we investigated the underlying mechanisms of training effects on human neutrophil apoptosis. Healthy male subjects were trained on a cycling ergometer for 8 weeks and followed by 4 weeks of detraining. Blood neutrophils were collected before exercise, after training, and after detraining. Comparing with pre-exercise specimens, neutrophils collected after training showed reduced apoptosis rate, which partially returned after detraining. Various intracellular proteins, including iNOS, Mcl-1, A1, Grp78, and IL-8, were upregulated by training, and they remained high after detraining. Upregulated iNOS was closely correlated with these anti-apoptotic molecules in neutrophils. Furthermore, the possible mechanism by which iNOS suppressed apoptosis was explored. Neutrophil apoptosis was accelerated by blocking and retarded by stimulating the endogenous iNOS activity. As an anti-apoptosis mediator of NO signaling, the Mcl-1 level dropped by depletion of the major NO downstream molecule cGMP and such loss of Mcl-1 was avoidable when supplying exogenous NO. Upon activation of NO-cGMP signaling, neutrophils held increased Mcl-1 expression and delayed apoptosis. Collectively, our results suggested that exercise training may retard neutrophil apoptosis by upregulating the iNOS-NO-cGMP-Mcl-1 pathway.
authors.affiliation: Institute of Medical Sciences, College of Medicine, Tzu Chi University, Hualien, Taiwan. shsuapril@mail.tcu.edu.tw
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Su
authors.forename: Chauying J
authors.initials: CJ
authors.lastname: Jen
authors.forename: Hsiun-ing
authors.initials: HI
authors.lastname: Chen
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D015444:Exercise; D006801:Humans; D008297:Male; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D015398:Signal Transduction; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D051017:Apoptosis Regulatory Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D009569:Nitric Oxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II