Showing papers by "Myron S. Cohen published in 1988"

Phagocyte-derived lactate stimulates oxygen consumption by Neisseria gonorrhoeae. An unrecognized aspect of the oxygen metabolism of phagocytosis.

Abstract: O2 consumption resulting from interaction of Neisseria gonorrhoeae and human neutrophils represents a composite of O2 consumed by the two cell systems. Experiments studying the relative contribution of each system suggested the possibility that gonococci increased their metabolic activity in response to interaction with neutrophils. This hypothesis was confirmed by demonstrating that undifferentiated HL-60 cells, which are unable to undergo a respiratory burst, induce a two- to three-fold increase in gonococcal O2 consumption. Gonococcal capacity to adhere to HL-60 cells did not correlate with extent of metabolic stimulation. Stimulatory activity was demonstrable in cell-free supernatant from neutrophils or HL-60 cells, and increased with duration of incubation. Supernatant applied to a G-15 Sephadex column yielded fractions that stimulated gonococcal O2 consumption. Elution profiles were similar for HL-60 cells, neutrophils, and a stimulatory factor previously isolated from pooled human serum. This stimulatory factor(s) failed to adhere to DEAE or C-18 HPLC columns. Stimulatory activity release from myeloid cells was inhibited by incubation at 4 degrees C or in the presence of NaF, indicating a critical role for glucose metabolism. Lactate, the principal product of resting neutrophil glucose catabolism, was demonstrable in cell-free supernatants after incubation at 37 degrees C. Lactate accumulation was inhibited by NaF and decreased temperature of incubation. Lactate at levels present in cell-free supernatant increased gonococcal O2 consumption twofold and restored stimulatory activity to dialyzed serum. Live, but not heat-killed gonococci eliminated lactate released from neutrophils during phagocytosis. Gonococci are able to utilize host-derived lactate to enhance their rate of O2 metabolism.

Phagocytes, O2 Reduction, and Hydroxyl Radical

Abstract: The formation of O2 reduction products by human neutrophils is critical to their elimination of potential pathogens. Hydroxyl radical is a potent oxidizing agent that may be formed by neutrophils through the iron-catalyzed reaction of superoxide and its dismutation product, hydrogen peroxide. Although indirect evidence has implicated hydroxyl radical in a variety of neutrophil-mediated processes, recent studies have not demonstrated hydroxyl radical formation by neutrophils unless an exogenous iron source and chelator were available, and even then neutrophils appear to limit formation of hydroxyl radical. By consuming hydrogen peroxide, the release of myeloperoxidase limits the magnitude of hydroxyl radical production. Lactoferrin released during neutrophil stimulation binds iron in a form incapable of catalyzing hydroxyl radical generation, thereby limiting both the magnitude and the duration of hydroxyl radical formation. Hydroxyl radical resulting from neutrophil superoxide production is likely to occur either in vitro or in vivo only when the target cell (or microenvironment) provides iron in an oxidation state and form capable of catalyzing the formation of hydroxyl radical and when neutrophil prevention systems are overwhelmed.

Exposure to myeloid and other mammalian cells increases Neisseria gonorrhoeae O2 utilization. Implications for pathogenesis

Abstract: O2 consumption induced by combining gonococci (GC) and neutrophils (PMN) was much higher than the sum of the two components’ individuals rates, suggesting PMN stimulated GC O2 uptake. The effect was independent of GC piliation, colony opacity, or serum resistance. The promyelocytic HL-60 cell line (which cannot undergo a “respiratory burst”) induced a 2–3 fold increase in GC O2 consumption, independent of GC phenotype. This appears secondary to a low molecular weight factor(s) released by the cells which may be similar to that previously described in human serum.

Use of the quinone antibiotic streptonigrin to explore the iron and oxygen metabolism of Neisseria gonorrhoeae . Mechanisms of antibiotic action and resistance

Abstract: Gonococci treated with the quinone antibiotic streptonigrin develop KCN insensitive respiration resulting in the formation of superoxide. Streptonigrin effects require iron suggesting that catalysis of hydroxyl radical is involved. We have found that extracellular iron appears to be more important than intracellular iron in these events. Highly streptonigrin resistant bacteria were isolated; these organisms demonstrated significant reduction in superoxide formation, and moderate reduction in total cellular iron. Iron transport mutants demonstrated superoxide fromation equivalent to the parent strain. Quinone antibiotics induce superoxide dismutase and catalase in E. coli, but this effect could not be demonstrated in gonococci. Our results suggest multiple possible mechanisms of streptonigrin resistance of N. gonorrhoeae including: failue to reduce the quinone; decreased intracellular iron, altered catalysis of hydroxyl radical at the cell surface.

An Expanded View of the Phagocytic Respiratory Burst

Abstract: Baldridge and Gerard in 19331 made the seminal observation that leukocyte consumption of ambient O2 increases markedly during the early stages of phagocytosis. Over the ensuing 43 years remarkable progress was made in characterizing the mechanisms and ramifications of this phenomenon, identified by Babior as the respiratory burst.2 Consumption of O2 by neutrophils and monocytes during phagocytosis leads to the purposeful formation of superoxide, a unique capacity of phagocytic cells. Production of superoxide and subsequent formation of other reactive oxygen intermediates (e.g., H2O2 and OCl-) is critical to the microbicidal activity of these cells.3 This is graphically demonstrated by the natural history of patients with chronic granulomatous disease (CGD) of childhood, whose phagocytes lack the capacity to develop a respiratory burst.3, 4