Oscillatory Pericellular Proteolysis and Oxidant Deposition During Neutrophil Locomotion

Proc. Natl. Acad. Sci. U.S.A.

2001

Self Cite

Self-organization is a common theme in biology. One mechanism of self-organization is the creation of chemical patterns by the diffusion of chemical reactants and their nonlinear interactions. We have recently observed sustained unidirectional traveling chemical redox [NAD(P)H ؊ NAD(P) ؉ ] waves within living polarized neutrophils. The present study shows that an intracellular metabolic wave responds to formyl peptide receptor agonists, but not antagonists, by splitting into two waves traveling in opposite directions along a cell's long axis. Similar effects were noted with other neutrophilactivating substances. Moreover, when cells were exposed to an N-formyl-methionyl-leucyl-phenylalanine (FMLP) gradient whose source was perpendicular to the cell's long axis, cell metabolism was locally perturbed with reorientation of the pattern in a direction perpendicular to the initial cellular axis. Thus, extracellular activating signals and the signals' spatial cues are translated into distinct intracellular dissipative structures.cell polarity ͉ nonequilibrium thermodynamics ͉ chemotaxis L iving cells continuously exchange matter and energy with their environment; they are open thermodynamic systems far from equilibrium (1, 2). Nonequilibrium conditions permit the appearance of dissipative structures, such as chemical concentration oscillations and chemical patterns. Dissipative structures use some of the energy absorbed from the environment to create order in a system (2). Chemical oscillators and chemical wave propagation, which do not violate the Second Law of Thermodynamics because they occur far from equilibrium, are well known in physical chemistry (2-4). Temporal oscillations in NAD(P)H (NADH ϩ NADPH) autofluorescence have been observed in living cells (5), including macrophages, monocytes, and neutrophils (6-8). These oscillations are the result of feedback activation and inhibition of glycolytic enzymes, especially phosphofructokinase (5, 9). For example, phosphofructokinase is activated by its proximal product, ADP, and inhibited by its substrate and distal product, ATP. Both temporal oscillations in NADH concentration and traveling NADH waves have been observed in macroscopic whole cell extracts (9-12). Theoretical studies have predicted the existence and properties of spatial glycolytic patterns in eukaryotic cells (13)(14)(15)(16)(17)(18). This has been recently confirmed by our group for NAD(P)H and pH (19). The present study tests the hypothesis that metabolic waves in living cells respond to extracellular signals. To observe these dissipative structures, we imaged microscopically NAD(P)H autofluorescence. We now report changes in the physical properties of traveling NAD(P)H waves in neutrophils during activation and signaling that reflect environmental orientational cues. These metabolic patterns are consistent with the ideas of Turing, Prigogine, Hess, and others concerning the potential role of dissipative chemical structures in biological function. Cells. Human peripheral blood neutrophils were purifi...

mentioning

confidence: 99%

RETRACTED: Dissipative metabolic patterns respond during neutrophil transmembrane signaling

Proc. Natl. Acad. Sci. U.S.A.

2001

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“…To explore the spatiotemporal coherence of these NAD(P)H waves and ROM release, high-speed microscopy was performed on spontaneously polarized neutrophils adherent to a substrate in phenol-red-free Hanks' balanced salt solution. Cell adherence͞ migration is sufficient to promote low levels of ROM production (22,23). Hanks' balanced salt solution contains 1 mM glucose, which approximates its concentration in blood and provides a large substrate reservoir for cell metabolism.…”

Section: Resultsmentioning

confidence: 99%

“…HE was added at 5 M to the extracellular environment to detect superoxide. When exposed to superoxide, HE, a nonfluorescent compound, is converted to EB, a highly fluorescent molecule (22). Cell autofluorescence was monitored in the region of 460 nm, because it is a reliable marker for metabolism and NAD(P)H levels [NAD(P) ϩ is nonfluorescent; e.g., refs.…”

Section: Resultsmentioning

confidence: 99%

“…Natural killer cells, as well as other types of immune cells, can discharge their contents vectorially toward a target (31). Previous findings suggested that ROMs are not released uniformly about the perimeter of neutrophils (22). Moreover, neutrophils with multiple attached targets have been shown to expose each target cell to ROMs sequentially, not simultaneously (32).…”

Section: Discussionmentioning

confidence: 95%

See 1 more Smart Citation

Apparent role of traveling metabolic waves in oxidant release by living neutrophils

Proc. Natl. Acad. Sci. U.S.A.

2002

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Cell metabolism self-organizes into two types of dissipative structures: chemical oscillations and traveling metabolic waves. In the present study we test the hypothesis that traveling NAD(P)H waves within neutrophils are associated spatially and temporally with the release of reactive oxygen metabolites (ROMs). Using high-speed optical microscopy and taking advantage of the autofluorescence of NAD(P)H, we have observed the propagation of NAD(P)H waves within cells. When NAD(P)H waves reach the lamellipodium of morphologically polarized neutrophils, a diffusing plume of superoxide is released as evidenced by the conversion of hydroethidine in the extracellular environment to ethidium bromide. Parallel results were obtained by using high-speed emission microspectrophotometry. These experiments indicate that the spatial and temporal properties of NAD(P)H waves are transformed into ROM pulses in the extracellular environment. Propagating NAD(P)H waves allow neutrophils to specifically deliver substrate to the lamellipodium at high concentrations, thus facilitating the local and periodic release of ROMs in the direction of cell movement and͞or a target.

“…To do this, the time dependence of NAD(P)H production as evidenced by NAD(P)H autofluorescence in adherent neutrophils was measured. As previously reported [38,39], adherent control neutrophils exhibit NAD(P)H oscillations with a period of about 20 seconds (Figure 2) at a glucose concentration of 1 mM. Glucose at 14 mM, a postprandial level that may be found in diabetic but not in lean or obese control subjects [37], decreases the oscillatory period to approximately 10 seconds ( Figure 2).…”

Section: Effect Of Glucose On Metabolic Dynamics In Cells From Pregnasupporting

confidence: 80%

Oxidant release is dramatically increased by elevated glucose concentrations in neutrophils from pregnant women

The Journal of Maternal-Fetal & Neonatal Medicine

Chaiworapongsa

et al. 2005

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Objective. To evaluate the mechanism of oxidative stress at glucose levels accompanying diabetic pregnancy. Specifically, we hypothesize that elevated glucose overwhelms hexose monophosphate shunt (HMS) down-regulation observed during pregnancy. Methods. Peripheral blood cells from normal healthy pregnant women were exposed to heightened glucose levels to provide an in vitro model of the effects of diabetic pregnancy. Changes in NAD(P)H, reactive oxygen species (ROS) and nitric oxide (NO) production were evaluated in single cells. Results. Altered metabolic dynamics, as judged by NAD(P)H autofluorescence of neutrophils from both pregnant and nonpregnant women, were observed during incubation with 14 mM glucose, a pathophysiologic level. In parallel, increased production of ROS and NO was observed. The ROS and NO levels attained in cells from pregnant women were greater than those observed in cells from non-pregnant women. Inhibitors of the HMS and NAD(P)H oxidase blocked these effects. These metabolic and oxidant changes required approximately one minute, suggesting that transient glucose spikes during pregnancy could trigger this response. Conclusions. Elevated glucose levels enhance HMS activity and oxidant production in cells from pregnant women. This mechanism may be generally applicable in understanding the role of diabetes in materno-fetal health.