Oxygen radicals in complement and neutrophil-mediated acute lung injury

The development of experimental acute lung injury following systemic complement activation is closely related to availability of blood neutrophils. Although tissue-destructive neutrophil-derived may play a supportive role in acute pulmonary injury, it appears that oxygen radical constitute the major neutrophil product responsible for acute damage of lung tissues and cells. Intravascular activation of neutrophils by the chemotactic complement peptide C5a is related to the generation os superoxide anion. Dismutation of superoxide to hydrogen peroxide and its iron-mediated conversion to hydroxyl radical appear to constitute in vivo events that ultimately lead to acute lung microvascular injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25857/1/0000420.pd

Mediator‐induced activation of xanthine oxidase in endothelial cells

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154271/1/fsb2003013008.pd

Protection by Vitamin B 2 Against Oxidant-Mediated Acute Lung Injury

The effect of vitamin B 2 (riboflavin) on oxidant-mediated acute lung injury has been examined in three different rat models. Pulmonary injury was induced by intravenous injection of cobra venom factor (CVF), by the intrapulmonary deposition of IgG immune complexes, or by hind limb ischemia-reperfusion. In each of the three models, injury was characterized by increases in vascular permeability (leakage of 125 I-labeled bovine serum albumin), alveolar hemorrhage (extravasation of 51 Cr-labeled rat erythrocytes), and neutrophil accumulation (myeloperoxidase activity). Intraperitoneal administration of riboflavin at a dose of 6 μmoles/kg body weight reduced vascular leakage by 56% in the CVF model, by 31% in the immune complex model, and by 53% in the lung injury model following ischemia-reperfusion of the hind limbs. Similar treatment reduced hemorrhage by 76%, 51%, and 70% in the three models of lung injury. In the CVF model, riboflavin was also shown to decrease products of lipid peroxidation (conjugated dienes) in lungs (by 45%) and in plasma (by 74%). Neutrophil accumulation in the lungs was not influenced by riboflavin administration in any of the three models. The studies demonstrate that riboflavin can mount a significant protection against oxidant-mediated inflammatory organ injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44527/1/10753_2004_Article_413169.pd

Lung injury and complement activation: Role of neutrophils and xanthine oxidase

Evidence is presented that oxygen products generated from xanthine oxidase (XO) may also be involved in the pathogenesis of neutrophil-mediate lung injury following intravascular activation of complement with cobra venom factor (CVF). CVF injection in rats resulted a rapid increase in plasma of both XO activity (but not xanthine dehydrogenase) and its reaction product, uric acid. These changes were greatly attenuated in allopurinol-treated animals. The apperance of XO activity was paralleled by a raise in plasma of histamine. Prevention of histamine release by pretreatment of rats withy cromolyn abolished both the rise in plasma histamine and the increase in XO activity. Since we have previously shown that histamine can enhance XO activity in vitro and in vivo (Am. J. Pathol. 135:203, 1989), these observations suggest that the increase in plasma XO activity following CVF injection is related to the appearance in plasma of histamine. Accordingly, pretreatment of rats with xanthine oxidase inhibitors (allopurinol, lodoxamine) or prevention of histamine release by pretreatment with cromolyn significantly attenuated development of lung injury following injection of CVF. Our data support the concept that oxygen radicals derived from both neutrophils and XO are playing a role in the CVF-induced acute lung injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29612/1/0000701.pd

Pathophysiology of leukocyte-mediated tissue injury

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29292/1/0000353.pd

Cutaneous thermal burn and oxidant-mediated acute lung injury: Appearance in serum of lung-related LDH isoenzyme

Previous studies from our laboratory have demonstrated that thermal injury to the skin of rats is associated with the production of oxygen radicals by complement-activated blood neutrophils, resulting in acute lung injury as demonstrated by increases in lung vascular permeability and morphological evidence of vascular endothelial cell damage, interstitial edema, and alveolar hemorrhage. In the present study, the analysis of sera from thermally injured rats reveals an isoenzyme profile for lactate dehydrogenase (LDH;EC 1.1.1.27) that is compatible with origin from lung. The appearance of LDH-4 isoenzyme in serum of thermally injured rats correlates linearly with indices of lung damage, supporting the results of previous studies suggesting that thermal trauma to the skin can cause oxygen radical production by complement-activated blood neutrophils with resultant acute microvascular injury in the lung interstitium. Furthermore, interventions that protect from oxidant-mediated lung injury (catase, scavengers of hydroxyl radical, iron chelators or neutrophil depletion) result in significant reductions in serum levels of the LDH-4 isoenzyme following thermal injury to the skin. Thus, measurements of LDH isoenzyme patterns in serum to be useful in monitoring tissue damage such as oxygen radical-mediated acute lung injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25898/1/0000461.pd

The effect of intravenous immunoglobulin on the in vitro function of human neutrophils

Three commercially available preparations of human immunoglobulin for intravenous use (IVIgG), namely Gamimune N, Sandoglobulin and Intraglobin F, were tested for their ability to modulate human neutrophil function in vitro. IVIgG consistently stimulated the neutrophil respiratory burst at concentrations of 0.5 to 1 mg/ml, concentrations readily achieved in vivo by moderate-dose therapy. Superoxide (O2-) release was increased by 3.5-4.5 nmol per 5 x 105 cells at these concentrations of IVIgG, and H2O2 production increased in a dose-dependent fashion up to 8 mg/ml IVIgG. Luminol-dependent chemiluminescence (CL) was also directly stimulated by IVIgG. In addition, the effects of both soluble and particulate stimulators (N-formyl-methionyl-leucyl-phenylalanine, phorbol myristate acetate and opsonized zymosan) on the neutrophil respiratory burst were enhanced by IVIgG. In a filter assay of neutrophil migration, using a modified Boyden chamber, no consistent effect on neutrophil locomotion or chemotaxis could be demonstrated. The effect of IVIgG on neutrophil metabolism may contribute to its beneficial therapeutic effect in severe, life-threatening infections.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27767/1/0000161.pd

Acute lung injury following intravascular complement activation; Association with toxic oxygen metabolites from neutrophils

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23825/1/0000064.pd

Complement depletion and persistent hemodynamic-hematologic responses in protamine-heparin reactions

Hypotension, bradycardia, pulmonary artery hypertension, neutropenia, and thrombocytopenia have been suspected to be due to complement activation following protamine reversal of heparin. This investigation examined these phenomena in complement-depleted animals. Eight dogs received intraperitoneal naja n. naja cobra venom factor (CVF), 20 U/kg, 48 and 24 hr prior to anticoagulation with sodium heparin, 150 IU/kg, and reversal 30 min later with protamine sulfate, 1.5 mg/kg. Decomplementation was confirmed in all dogs. Systemic blood pressure (BP), pulse (HR), pulmonary artery systolic and diastolic pressures, (PAS, PAD), cardiac output (CO), platelet count (PTC), and white blood count (WBC) with differential were monitored. The maximal mean changes for the entire group were BP, -43 mm Hg; HR, -16; PAS, +6 mm Hg; PAD, +3 mm Hg; CO, -27%; PTC, -49%; and WBC, -48%. These hemodynamic and hematologic responses, occurring in the face of CVF-induced decomplementation, support the conclusion that complement components C3 and C5-C9 are not influential factors contributing to these protamine-heparin-induced events.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27158/1/0000153.pd

Mediators of Microvascular Injury in Dermal Burn Wounds

In previous studies we have demonstrated that second-degree thermal injury of skin in rats leads to secondary effects, such as systemic complement activation, C5a-mediated activation of blood neutrophils, their adhesion-molecule-guided accumulation in lung capillaries and the development of acute pulmonary injury, largely caused by neutrophil-derived toxic oxygen metabolites. In the dermal burn wound, however, pathophysiologic events are less well understood. The injury is fully developed at four hours post-burn. To further elucidate the pathogenesis of the “late phase” dermal vascular damage, rats were depleted of neutrophils or complement by pretreatment with rabbit antibody against rat neutrophils or with cobra venom factor, respectively. In other experiments, rats were treated with blocking antibodies to IL-6, IL-1, and TNFα immediately following thermal burning or were pretreated with hydroxyl radical scavengers (dimethyl sulfoxide, dimethyl thiourea). Extravasation of 125 I-labeled bovine serum albumin into the burned skin was studied, as well as, skin myeloperoxidase levels. The studies revealed that, like in secondary lung injury, neutrophils and toxic oxygen metabolites, are required for full development of microvascular injury. In contrast, however, development of dermal vascular damage in thermally injured rats was not affected by complement depletion. Our data suggest that the development of microvascular injury in the dermal burn wound is complement-independent, involves the pro-inflammatory cytokines IL-1, TNFα and IL-6, and may result from reactive oxygen metabolites generated by neutrophils accumulating in the burn wound.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44523/1/10753_2004_Article_415307.pd