Continuous infusion of Escherichia coli endotoxin in vivo primes in vitro superoxide anion release in rat polymorphonuclear leukocytes and Kupffer cells in a time-dependent manner

Abstract

Continuous infusion of a nonlethal dose of Escherichia coli lipopolysaccharide (LPS) (0.5 mg/kg) in#dced early (3 h) accumulation of polymorphonuclear leukocytes (PMNL) in rat liver followed by later (30 h) greater extravasation of mononuclear phagocytes (MNP) (E. B. Rodriguez de Turco and J. A. Spitzer, J. Leukocyte Biol. 48:488-494, 1990). Nonparenchymal liver cells from rats treated for 3 and 30 h with LPS were recovered by centrifugal elutriation, yielding a 23-ml/min fraction (endothelial cells) and a 45-ml/min fraction (PMNL, Kupffer cells, and MNP), and compared for their capacity for basal and agonist-stimulated superoxide (02 ) production. Stimulation with phorbol myristate acetate and opsonized zymosan caused a dose-dependent release Of 02 from the 45-ml/min fraction derived from rats treated for 3 h with saline, but not from the 23-ml/min fraction. Further purification of the 45-ml/min fraction by discontinuous density gradient centrifugation into a Kupifer and a PMNL fraction revealed that most of the agonist-induced 02 release was generated by infiltrating PMNL at this early time point of LPS infusion. By 30 h of LPS infusion, although enhancement of the phorbol-12-myristate-13-acetateand opsonized zymosan-stimulated release of 02 was observed in the 45-ml/min fraction, but not in the 23-ml/min fraction, the maximum release of 02was smaller than that observed in the rats treated for 3 h. Our results support the following conclusions: (i) after a 3-h LPS infusion, PMNL found in the liver in increased numbers are also highly primed for agonist-stimulated release of 02while Kupifer cell priming is of a lesser extent; (ii) after a 30-h infusion of LPS, infiltrating MNP found in the liver in increased numbers are primed for agonist-induced 02 release, while priming of PMNL has diminished; (iii) at both 3 and 30 h of LPS infusion, liver endothelial cells are not significantly primed for agonist-stimulated 02 release; and (iv) in vivo priming by LPS infusion at both 3 and 30 h was not reversed by the experimental method used for cell recovery (ca. 3 h), thus suggesting that in vivo LPS priming of 02 release may ultimately lead to severe impairment of liver function and metabolism observed during endotoxemia and sepsis if not therapeutically blocked at an early time point.

Cytokine stimulation of nitric oxide formation and differential regulation in hepatocytes and nonparenchymal cells of endotoxemic rats

“…They may also be effector cells for immune responses; they present different surface antigens (37 ). We demonstrated earlier that participation of these cells in superoxide production after i n uiuo ET exposure and in response to stimulation by various agents i n uitro is far less than that by Kupffer cells or liver-sequestered neutrophils ( 19). In a later publication McCloskey et al (38) also demonstrated in a different endotoxic model the substantial quantitative difference in superoxide anion production between hepatic macrophages and endothelial cells.…”

“…The nonparenchymal sinusoidal cells of the liver includein addition to Kupffer cellsendothelial, Ito and pit cells. Previously we demonstrated phorbol myristate acetate (PMA)-stimulated superoxide anion release by hepatic endothelial cells of continuously endotoxemic rats to a much smaller extent than that by Kupffer cells and liver infiltrated polymorphonuclear cells from such animal models (19). In Figure 6 evidence is presented for NO production by hepatic endothelial cells of saline solution-and ET-infused rats in the absence and presence of ET, TNF, IL-1p and various combinations of these agents.…”

Disparities in the respiratory burst between human and rat neutrophils

“…Previous investigators have noted that O 2 Ϫ release from rat PMNs appears to be a fraction of that produced by human PMNs. However, the majority of previously published work on rat PMNs has been performed on elicited PMNs [5,9,11,[26][27][28], which may be functionally different from quiescent PMNs. We hypothesized that this disparity in measured O 2 Ϫ formation is because the rat PMN preferentially releases other oxidant species during the respiratory burst and we sought to test this hypothesis in the quiescent, circulating rat neutrophil.…”

“…In efforts to elucidate the mechanisms of ROS-mediated PMN cytotoxicity and, indeed, to develop effective therapeutic strategies, many productive animal models of inflammatory states have been developed. ROS-mediated tissue injury by PMNs has been implicated in models of ARDS [3], ischemia/ reperfusion [4], and sepsis [5] through the use of appropriate analogs. As with any animal model, however, species differences may limit the conclusions that can be reasonably reached.…”

Neutrophil migration during endotoxemia

“…Tissue injury during endotoxemia is often attributed to PMN-derived reactive oxygen species (ROS), and treatment with antioxidants or blocking PMN function can prevent endotoxemia-related pulmonary injuries [42]. Some studies suggest that adhered or tissue-associated PMNs demonstrate even greater oxidant potential than circulating PMNs during endotoxemia [4,43,44]. However, instances of depressed or unaltered oxidant production by PMNs during endotoxemia are also reported [45][46][47].…”