title: Endogenous PMN-derived reactive oxygen intermediates provide feedback regulation on respiratory burst signal transduction.
abstract: The role of polymorphonuclear leukocytes (PMN) in stemming systemic infection is executed mainly by the utilization of molecular O2 leading to the production of reactive oxygen intermediates (ROI). PMN-derived ROI also serve as intra- and extracellular second messengers providing both positive and negative feedback on cellular autoregulation. We investigated the effect of endogenous ROI on two signal transducing pathways: the receptor (R)-G-protein-phospholipase D (PLD) and receptor (R)-G-protein-phospholipase C pathways responsible for the subsequent interleukin-8 (IL-8)-induced PMN respiratory burst. Purified human PMN were primed with LPS adhered to plastic surfaces and stimulated with IL-8 with or without the presence of each of five different selective ROI scavengers/antioxidants: DMSO, N(a)N3, L-alanine, catalase, or superoxide dismutase. Total IL-8 surface receptor expression was assessed by 125I-IL-8 and 125I-labeled mAbs against IL-8R type A and B binding assays; PLD activation was assessed by measuring formation of phosphatidyl ethanol (PEt) in the presence of ethanol; PLC activation was measured by quantitative conversion of [32P]ATP-labeled phosphatidic acid (PA) into diacylglycerol (DAG); expression of G alpha-inhibitory subunit was assessed by SDS-PAGE and immunoblotting with polyclonal Abs against this subunit. Production of O2-, H2O2, HClO, and myeloperoxidase (MPO) in the experimental model was confirmed in a separate set of experiments. The overall impact of antioxidants on each component of the transducing tripartite complex was stimulatory; however, N(a)N3 and SOD exhibited the most ubiquitous effect with consistent up-regulation by N(a)N3 of IL-8R expression, whereas even trace amounts of externally added authentic MPO significantly down-regulated the functional activity of both effector enzymes. These results demonstrate a multiple site-specific targeting of the signal-transducing complex by endogenous PMN-derived ROI and an overall protective effect of ROI scavengers/antioxidants.
authors.affiliation: Brown University School of Medicine/Rhode Island Hospital, Department of Surgery, Providence 02903, USA.
authors.forename: A
authors.initials: A
authors.lastname: Derevianko
authors.forename: R
authors.initials: R
authors.lastname: D'Amico
authors.forename: T
authors.initials: T
authors.lastname: Graeber
authors.forename: H
authors.initials: H
authors.lastname: Keeping
authors.forename: H H
authors.initials: HH
authors.lastname: Simms
mesh_terms: D000409:Alanine / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005246:Feedback; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009504:Neutrophils / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism; D017382:Reactive Oxygen Species; D018123:Receptors, Interleukin / Q000378:metabolism; D023062:Receptors, Interleukin-8A; D016897:Respiratory Burst; D015290:Second Messenger Systems; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D000975:Antioxidants; D001386:Azides; D016209:Interleukin-8; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D018123:Receptors, Interleukin; D023062:Receptors, Interleukin-8A; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D010738:Type C Phospholipases; D010739:Phospholipase D; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D000409:Alanine