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H H Simms

Publications and source records attributed to H H Simms.

At least 37 records · Page 2Linked to original sources
PubMed1997

Posttraumatic auto-oxidative polymorphonuclear neutrophil receptor injury predicts the development of nosocomial infection.

OBJECTIVE: To determine the mechanisms and prevalence of posttraumatic auto-oxidative receptor injury and immune suppression to subsequent nosocomial infections. DESIGN: Purified polymorphonuclear neutrophils from 30 critically ill trauma patients (mean [+/- SD] Injury Severity Scores, 21.5 +/- 7.3) were incubated with glucose and glucose-oxidase to generate superoxide anion. Subcellular fractionations were performed with iodine 1125 monoclonal antibodies against the Fc receptors CD32w and CD16 and complement receptors CD35 and CD11b/CD18. Plasma membrane expression of these receptors was then determined during the first week of hospitalization. SETTING: Surgical intensive care unit in a university-affiliated hospital. RESULTS: Twenty-three (77%) of 30 patients had persistent auto-oxidative reduction in Fc and complement receptors induced by glucose and glucose-oxidase. Nosocomial infections occurred in 20 (87%) of 23 patients with auto-oxidative injury vs 1 (14%) of 7 patients without auto-oxidative receptor injury (P < .01, unpaired t test). Patients without auto-oxidative injury had expression for each receptor no different from buffer control. CONCLUSIONS: Critically ill trauma patients have auto-oxidative receptor injury, which is closely linked with the development of nosocomial infections. These results provide a biological basis for the early use of auto-oxidants in critically ill trauma patients.

Cross Infection↗
PubMed1997

Endogenous PMN-derived reactive oxygen intermediates provide feedback regulation on respiratory burst signal transduction.

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.

Alanine↗
PubMed1997

Studies on polymorphonuclear leukocyte bactericidal function III: the role of extracellular matrix proteins.

We investigated the effect of the extracellular matrix proteins fibronectin (Fn) and laminin (Ln) on polymorphonuclear leukocytes (PMN) bactericidal activity. Adherence of PMN to increasing concentrations of Ln significantly increased the killing of Escherichia coli after 240 min of adherence, while fibronectin significantly increased PMN staphlacidal activity after 240 min of adherence. The addition of IL-1beta and IL-8 but not TNF-alpha increased PMN bactericidal activity against E. coli when PMN were adhered to Ln, while TNF-alpha and IL-8 increased PMN bactericidal activity against Staphylococcus aureus when PMN were adhered to Ln. TNF-alpha increased PMN killing of E. coli when PMN were adhered to Fn, while only IL-1beta increased the killing of S. aureus when PMN were adhered to FN. Anti-VLA-3 (alpha3/beta1) monoclonal antibodies (mAbs) inhibited the effect of Ln on PMN bactericidal activity, while anti-VLA-5 (alpha5/beta1) mAbs inhibited the effect of Fn on PMN bactericidal activity. Progressive cross-linkage of these two receptors led to a dose-dependent reduction in PMN bactericidal activity for both pathogens when PMN were adhered to Ln or Fn, respectively. These results demonstrate that extracellular matrix proteins +/- exogenously added cytokines have the capacity to regulate PMN bactericidal activity. The signals sent by these matrix proteins to increase PMN bactericidal activity are transduced primarily via separate alpha subunits of the beta1 integrin complex. Stimulation of these receptors might lead to potential upregulation of PMN bactericidal activity which would be potentially advantageous in vivo at sites of infection.

Animals↗
PubMed1997

Integrin regulation of polymorphonuclear leukocyte apoxis during hypoxia is primarily dependent on very late activation antigens 3 and 5.

BACKGROUND: Apoptosis is thought to be a central mechanism that leads to resolution of the inflammatory response. The regulation of polymorphonuclear leukocyte (PMN) apoptosis during hypoxia has not been previously characterized, and we hypothesized that integrin signaling by matrix proteins (laminin) would regulate PMN apoptosis. METHODS: PMNs at 1 x 10(5)/ml were adhered on plastic or laminin for 12 hours during normoxia or hypoxia. Apoptosis was determined both by cellular histologic evaluation and the TUNEL assays (Tdt). Phagocytosis in apoptotic PMNs was determined with two-color flow cytometric analyses with rhodamine-labeled heat-killed Escherichia coli (511 nm) and the Tdt reagent (563 nm). Western blot analyses were performed on nine apoptotic regulatory proteins with monoclonal antibodies directed against each protein, and tyrosine phosphorylation was assessed after integrin receptor cross-linkage. RESULTS: Adherence of PMNs to laminin reduced apoptosis by cellular histologic evaluation and the Tdt method (%apoptosis = 19 +/- 1.0 versus 63 +/- 4.2 by histologic evaluation, 38 +/- 3.8 versus 60 +/- 10.5 by flow cytometry +/- adherence to laminin). Apoptosis-positive PMNs exhibited significantly greater phagocytosis than apoptosis-negative PMNs +/- laminin. Western blot analyses demonstrated increased p53 expression after 2 and 4 hours of hypoxia. Cross-linkage of very late activation antigen-3 (alpha 3/beta 1) resulted in the phosphorylation of 53 kd, 44 kd, and 39 kd proteins at 30 seconds. CONCLUSIONS: (1) Chemotaxis of PMNs into the interstitium during hypoxia not only provides a means of ensuring PMN-pathogen contact but also provides a mechanism for improved survival by reducing apoptosis. (2) The reduction of apoptosis is mediated primarily by very late activation antigen-3, which leads to a subsequent increase in the intracellular expression of p53 and increased bacterial phagocytosis.

Apoptosis↗
PubMed1997

Integrin stimulation regulates polymorphonuclear leukocytes inflammatory cytokine expression.

OBJECTIVE: The purpose of these studies is to investigate the role of integrin binding on the regulation of polymorphonuclear leukocyte (PMN) cytokine receptor expression. SUMMARY BACKGROUND DATA: Current knowledge in this area revolves around the ability of beta 2 integrins to mediate PMN adherence and chemotaxis. The role of alpha 1-6/beta 1 integrins in regulating cytokine receptor expression has not been probed. METHODS: Purified human PMN were adhered on plastic, fibronectin, or laminin-coated surfaces followed by the addition of iodine 125 (125I) monoclonal antibodies (mAbs) directed against tumor necrosis factor-alpha R (TNF-alpha R) p60, p80, or interleukin-1 beta R (IL-1 beta R) types I, II. Receptor expression was calculated based on the counts per minute (cpm) bound. The role of individual beta 1 integrins was assessed using mAbs directed against the alpha 1-6 subunit of the beta 1 complex, and integrin cross-linkage was achieved using secondary goat antimouse F(ab')2 antibodies. Polymorphonuclear leukocytes were pretreated with herbimycin A to determine the role of protein tyrosine kinase in mediating the effect of the beta 1 integrins. RESULTS: Adherence of PMN to Ln decreased IL-1 beta types I, II receptor expression, whereas adherence to Fn increased TNF-alpha R p60 and p80 expression. Anti-VLA-5 (CD49e) but not anti-VLA-1 through VLA-4 and VLA-6, blocked the effect of Fn on TNF-alpha receptors, whereas anti-VLA-6 but not anti-VLA-1 through VLA-5 blocked the effect of Ln on IL-1 beta receptors. Modulation of IL-1 beta and TNF-alpha receptors by VLA-5 and VLA-6 required protein tyrosine kinase activation as herbimycin A (10 micrograms/mL) blocked the affect of Fn and Ln. Changes in PMN cytokine receptor expression led to parallel changes in functional activity as assessed by the binding of 125I IL-1 beta and TNF-alpha. CONCLUSIONS: Integrin stimulation regulates the cell surface expression of PMN cytokine receptors. Ligation of CD49e upregulates TNF-alpha receptor expression, whereas binding of CD49f downregulates IL-1 beta receptor expression. Both processes are protein tyrosine kinase dependent. Changes in PMN cytokine receptor expression led to corresponding changes in functional activity. These results provide the first demonstration that chemotaxis of PMN into the interstitium provides a mechanism for ongoing participation in the local inflammatory response and is regulated by matrix protein integrin receptors.

Antibodies, Monoclonal↗
PubMed1997

Studies on polymorphonuclear leukocyte bactericidal function: the role of exogenous cytokines.

We investigated the effects of exogenous cytokines (interleukin (IL)-8, tumor necrosis factor (TNF)-alpha, and IL-1 beta) on polymorphonuclear neutrophil (PMN) bactericidal activity against both Staphylococcus aureus and Escherichia coli. Both baseline and IL-8-stimulated PMN bactericidal activity against E. coli, but not against S. aureus, declined significantly from 0 to 240 min. The decline in bactericidal activity was prevented by TNF-alpha, but not IL-1 beta. Bactericidal activity against both E. coli and S. aureus declined as PMN:target ratios went from 20:1 to 5:1. TNF-alpha and IL-1 beta preserved bactericidal activity even at a 5:1 PMN:target ratio against E. coli, whereas all three cytokines preserved bactericidal activity at a 5:1 PMN:target ratio against S. aureus. Dose-response curves demonstrated significant increases in bactericidal activity with physiologically relevant concentrations of cytokines (IL-8: .1-10 ng/mL; TNF-alpha: 1-10(2) U/mL; and IL-1 beta: 0-10 ng/mL). Binding of cytokine receptors with monoclonal antibodies directed against IL-8R Type A, TNF-alpha R (p60) or (p80), and IL-1 beta R Type I significantly reduced the effect of individual cytokines on PMN bactericidal activity. Inhibition of terminal, but not proximal, products of the PMN oxidative burst significantly reduced the effect of exogenous cytokines on PMN bactericidal activity. These results demonstrate that individual cytokines at relatively low concentrations enhance PMN bactericidal activity via oxidant-dependent mechanisms and that inhibiting cytokine functions may not be advantageous at infectious foci in vivo.

Antioxidants↗
PubMed1997

Cytokine control of PMN phagocytosis: regulatory effects of hypoxemia and hypoxemia-reoxygenation.

We investigated the effects of hypoxemia and hypoxemia-reoxygenation (H/R) on interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha), or IL-1beta stimulation of whole blood polymorphonuclear leukocyte (PMN) phagocytosis and bactericidal activity. Whole blood PMN were rendered hypoxemic (venous PO2 < 15 mmHg), normoxic (venous PO2 60-80 mmHg), or reoxygenated after hypoxemia (H/ R = venous PO2 150-200 mmHg) and were incubated with IL-8, TNF-alpha, or IL-1beta before sequential addition of serum-opsonized fluorescent microspheres and fluorescein isothiocyanate-conjugated mouse anti-human CD64, CD32w, CD16, CD35, or CD11b/CD18. Concomitant two-color flow cytometric analyses were then performed measuring mean channel fluorescence and the percentage of PMN positive for phagocytosis, with simultaneous subset receptor analysis on populations of PMN that exceeded control levels of phagocytosis. During hypoxemia, whole blood PMN phagocytosis in the presence of IL-8, TNF-alpha, or IL-1beta was increased compared with normoxia. Northern blot analyses revealed an increase in steady-state mRNA levels for CD32w during hypoxemia + IL-8 and CD64 during hypoxemia + IL-1beta. During reoxygenation, both whole blood PMN phagocytosis and bactericidal activity were reduced in the presence of IL-8, TNF-alpha, or IL-1beta, and in subsets of PMN with reduced phagocytosis H/R reduced CD64, CD32w, CD16, CD35, and CD11b/CD18 expression in the presence of each cytokine. Northern blot analyses revealed that H/R reduced mRNA levels for opsonic receptors primarily for IL-1beta-stimulated PMN. These results demonstrate a direct regulatory effect of hypoxemia and H/R on whole blood PMN phagocytosis, receptor expression, and steady-state mRNA levels of both Fc(gamma) and complement receptors.

Animals↗
PubMed1997

Studies on polymorphonuclear leukocyte bactericidal function: II. The role of oxidative stress.

We have previously detailed the effects of exogenous cytokines (IL-1 beta, TNF-alpha, and IL-8) on polymorphonuclear leukocyte (PMN) bactericidal function during normoxia. In these studies, we have investigated the effects of hypoxia +/- reoxygenation independently and with IL-1 beta, TNF-alpha, and IL-8 on PMN bactericidal activity. Hypoxia in and of itself did not significantly alter PMN bactericidal activity against Escherichia coli or Staphylcoccus aureus; however, after 2 h of reoxygenation (H/R), PMN bactericidal activity against E. coli was significantly reduced compared with levels seen after 2 h of hypoxia. Similar to what was observed during normoxia, TNF-alpha, IL-1 beta, and IL-8 increased PMN bactericidal activity during hypoxia compared with buffer control PMN for S. aureus but not E. coli after 4 h of hypoxia. Following H/R, neither TNF-alpha, IL-1 beta, nor IL-8 reversed the decline in bactericidal activity induced by reoxygenation alone. Monoclonal antibodies that blocked the functional epitope of particular cytokine receptors demonstrated that during both hypoxia and H/R IL-1 beta R type I, IL-8R type A, and TNF-alpha R p60 were the predominant receptors responsible for mediating the bactericidal effect of the cytokines. During hypoxia and H/R, the addition of exogenous cytokines did prevent the fall in bactericidal activity seen as PMN: target ratios decreased. The decline in bactericidal activity following H/R was mediated in part by reduced phagocytosis of serum-opsonized bacteria following H/R. These results demonstrated that oxidative stress in the form of hypoxia +/- reoxygenation independently modulate the effect of exogenously added cytokines on PMN bactericidal capability.

Blood Bactericidal Activity↗
PubMed1997

Abdominal compartment syndrome: case reports and implications for management in critically ill patients.

Five cases are reviewed in which intra-abdominal pressures were used to decide whether critically ill patients would undergo exploratory laparotomy. This is a retrospective case series of a convenience sample of five critically ill, postoperative patients with a variety of underlying illnesses admitted to a surgical intensive care unit in a university hospital. Intra-abdominal compartment pressures were measured using the indirect method of urinary bladder pressure. In patients with signs of abdominal compartment syndrome, intra-abdominal pressures were measured. The pressures were measured every 6 hours until the signs had resolved or the patient was taken for exploratory laparotomy. All patients had Foley catheters. The drainage tubing to the catheters was clamped after the infusion of 200 cc of sterile water. An 18-gauge needle was inserted into the sampling port of the drainage tubing proximal to the clamp, and the needle was connected to a pressure transducer. An elevated abdominal compartment pressure was considered at greater than 25 mm Hg. The case series were reviewed to determine in critically ill patients whether intra-abdominal pressures could assist in deciding which patients required emergent exploratory laparotomy. The patients underwent frequent venous and arterial blood gas and hemodynamic measurements. If the clinical course of the patients worsened as indicated by requiring additional pressors, ventilator support and/or oliguria intra-abdominal pressures were measured every 6 hours. The five patients whose intra-abdominal pressures were elevated were taken for exploratory laparotomy. Four patients were found to have urgent surgical conditions. Intra-abdominal pressures can be used to help decide which patients can be aggressively supported and observed and which patients need re-exploration. At exploration the patient may be found to have necrotic large or small intestines instead of the classical abdominal compartment syndrome findings of ascites, hematoma, and bowel wall edema. In symptomatic patients with abdominal compartment pressures greater than 30 mm Hg, the patient should be taken for exploration. It is not necessary to perform any further diagnostic tests before exploring the patient.

Abdomen↗
PubMed1996

Cytokine-mediated human polymorphonuclear neutrophil phagocytosis: evidence of differential sensitivities to manipulation of intracellular mechanisms.

Interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) are well known mediators in infectious processes with pleiotropic effects on a variety of cells. These cytokines are known to upregulate Fc receptor (Fc gamma R)-mediated phagocytosis by human polymorphonuclear neutrophils (PMN) but the mechanisms of this enhanced phagocytosis are not known. We investigated the effects of various alterations in intra- and extracellular events on cytokine-induced phagocytic upregulation. Blockade of mRNA synthesis, protein kinase C activation, or G protein activation prevented enhanced phagocytosis by either cytokine. The PMN phagocytic response to TNF-alpha, but not IL-1 beta, was also blunted by agents interfering with mRNA translation or Fc gamma R recycling.

Animals↗
PubMed1996

Results of a randomized trial comparing sequential intravenous/oral treatment with ciprofloxacin plus metronidazole to imipenem/cilastatin for intra-abdominal infections. The Intra-Abdominal Infection Study Group.

OBJECTIVE: In a randomized, double-blind, multicenter trial, ciprofloxacin/metronidazole was compared with imipenem/cilastatin for treatment of complicated intra-abdominal infections. A secondary objective was to demonstrate the ability to switch responding patients from intravenous (IV) to oral (PO) therapy. SUMMARY BACKGROUND DATA: Intra-abdominal infections result in substantial morbidity, mortality, and cost. Antimicrobial therapy often includes a 7- to 10-day intravenous course. The use of oral antimicrobials is a recent advance due to the availability of agents with good tissue pharmacokinetics and potent aerobic gram-negative activity. METHODS: Patients were randomized to either ciprofloxacin plus metronidazole intravenously (CIP/MTZ IV) or imipenem intravenously (IMI IV) throughout their treatment course, or ciprofloxacin plus metronidazole intravenously and treatment with oral ciprofloxacin plus metronidazole when oral feeding was resumed (CIP/MTZ IV/PO). RESULTS: Among 671 patients who constituted the intent-to-treat population, overall success rates were as follows: 82% for the group treated with CIP/MTZ IV; 84% for the CIP/MTZ IV/PO group; and 82% for the IMI IV group. For 330 valid patients, treatment success occurred in 84% of patients treated with CIP/MTZ IV, 86% of those treated with CIP/MTZ IV/PO, and 81% of the patients treated with IMI IV. Analysis of microbiology in the 30 patients undergoing intervention after treatment failure suggested that persistence of gram-negative organisms was more common in the IMI IV-treated patients who subsequently failed. Of 46 CIP/MTZ IV/PO patients (active oral arm), treatment success occurred in 96%, compared with 89% for those treated with CIP/MTZ IV and 89% for those receiving IMI IV. Patients who received intravenous/oral therapy were treated, overall, for an average of 8.6 +/- 3.6 days, with an average of 4.0 +/- 3.0 days of oral treatment. CONCLUSIONS: These results demonstrate statistical equivalence between CIP/MTZ IV and IMI IV in both the intent-to-treat and valid populations. Conversion to oral therapy with CIP/MTZ appears as effective as continued intravenous therapy in patients able to tolerate oral feedings.

Abdomen↗
PubMed1996

Altered oxygen tension modulates cytokine-induced signal transduction in polymorphonuclear leukocytes: regulation of the GPLD pathway.

We investigated the effect of alterations in buffer oxygen tensions from normoxia (PO2 = 180-200 mm/Hg) to hypoxia (PO2 < 30 mm/HG) and then reoxygenation (PO2 > 140 mmHg) on the GPLD-pathway by measuring phosphatidylethanol formation in the presence of ethanol and subsequent NADPH oxidase activation and O2-production in polymorphonuclear leukocytes (PMN). Experiments were performed with PMN stimulated with either interleukin (IL)-8, tumor necrosis factor (TNF)-alpha, or IL-1 beta in the presence or absence of fibronectin. Hypoxia exerted a downregulating effect on this pathway and reoxygenation restored GPLD activation to levels seen during normoxia; however, supraphysiological concentrations of cytokines were able to reverse this pattern. Changes in GPLD activation correlated best with changes in O2-production during the hypoxia to hypoxia/reoxygenation transition induced by TNF-alpha-Fn and IL-1 beta +/- Fn. Thus, changes in oxygen tension can directly modulate the extent of the PMN response to stimulation by IL-8, TNF-alpha, or IL-1 beta, and activation of the GPLD-pathway appears to be highly sensitive to hypoxia and hypoxia/reoxygenation.

Adenosine Triphosphate↗
PubMed1995

Subcellular location of neutrophil opsonic receptors is altered by exogenous reactive oxygen species.

The effect of exposure of PMN to extracellular oxidants on the PMN oxidative burst on the subcellular location of CD64 (Fc gamma RI), CD32w (Fc gamma RII), CD16 (Fc gamma RIII), CD35 (complement receptor 1), and CD11b/CD18 (complement receptor 5) was studied. Incubation of PMN with glucose/glucose oxidase resulted in an intracellular shift in Fc gamma receptors from secretory vesicles to plasma membrane fractions while reducing complement receptor expression in plasma membrane fractions. Incubation of PMN with xanthine/xanthine oxidase resulted in an intracellular shift in Fc gamma receptors from specific granules to secretory vesicles. Incubation of PMN with xanthine/xanthine oxidase resulted in an intracellular shift from secretory vesicles to plasma membrane fractions for CD35 and from secretory vesicles and specific granules to plasma membrane fractions for CD11b/CD18. The effects of glucose/glucose oxidase and xanthine/xanthine oxidase on receptor redistribution were blocked by catalase and catalase and superoxide dismutase, respectively. Cytoskeleton stabilization with phalloidin and Taxol blocked the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on Fc gamma and complement receptor relocation. Both H-7 and staurosporine abrogated the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on Fc gamma receptor relocation, while genistein abrogated the effect of glucose/glucose oxidase and xanthine/xanthine oxidase on complement receptor relocation. Increases in CD64, CD32w, CD16, CD35, and CD11b/CD18 expression associated with plasma membrane fractions corresponded to functional increases in monomeric IgG binding, E-IV.3, (sheep erythrocyte opsonized with monoclonal antibody IV.3 directed against CD32w) E-Con A, EC3b, and EC3bi rosetting. These studies indicate that exposure of PMN to extracellular oxidants does not occur as an isolated event but results in a coordinated subcellular relocation of opsonic receptors which corresponds to changes in PMN function.

Catalase↗
PubMed1995

Hypoxemia up-regulates interleukin-8 stimulated phagocytosis of polymorphonuclear leukocytes by differential regulation of CD32w and CD35 messenger RNA expression.

BACKGROUND: The purpose of these studies was to investigate the effect of hypoxemia on interleukin-8 (IL-8) regulation of phagocytosis and surface opsonic receptor expression of whole blood polymorphonuclear leukocytes (PMNs). METHODS: Whole blood PMNs were rendered hypoxemic (PvO2 less than 15 mm Hg) or normoxic (PvO2 equals 60 to 80 mm Hg) and incubated with IL-8 (50 ng/ml) before the sequential addition of serum-opsonized fluorescent microspheres (emission wavelength, 560 nm) and fluorescein isothiocyanate-conjugated mouse anti-human CD32w or CD35 antibodies (emission wavelength, 513 nm). Concomitant two color flow cytometric analysis was then performed to measure the mean channel fluorescence (MCF) and the percentage of positive PMNs. Steady-state messenger RNA levels for CD32w and CD35 were quantitated by means of Northern blot analysis by using total RNA extracted from purified PMNs from each study group. RESULTS: Hypoxemia increased IL-8 stimulated PMN phagocytosis (percentage of positive PMNs, 38 +/- 1.5 versus 27 +/- 2.0, MCF, 5491 +/- 182 versus 4060 +/- 121 for hypoxemia plus IL-8 versus normoxia plus IL-8, respectively; p < 0.05). Hypoxemia increased IL-8 stimulated PMN expression of CD32w and CD35 (MCF CD32w, 791 +/- 105 versus 336 +/- 81; MCF CD35, 542 +/- 87 versus 254 +/- 41; p < 0.05). Under normoxic conditions IL-8 decreased messenger RNA levels for both CD32w and CD35, but under hypoxemic conditions IL-8 increased messenger RNA levels only for CD32w. CONCLUSIONS: Hypoxemia directly regulates IL-8 control of PMNs by increasing phagocytosis, receptor expression, and messenger RNA for these receptors. Studies investigating cytokine regulation of PMN function need to take into account oxygen tension when establishing the fundamental effects of cytokines on PMN physiology.

Cytokines↗
PubMed1995

Lipopolysaccharide induces intracytoplasmic migration of the polymorphonuclear leukocyte CD11b/CD18 receptor.

We investigated the effects of lipopolysaccharide (LPS) on the subcellular location of the integrin receptor CD11b/CD18 (Mac-1). Cytoplast and subcellular fractionation experiments were performed to distinguish between receptor shedding and intracellular receptor transport as mechanisms involved for the effects of LPS on CD11b/CD18 expression. Cytoplast preparations demonstrated the same percentage of cell-associated receptors +/- LPS. Subcellular fractionation experiments demonstrated a shift from primarily plasma membrane fractions to azurophilic granules. Protein tyrosine kinase inhibition with genistein (50 microM) inhibited the LPS-induced translocation of CD11b/CD18 receptors to azurophilic granules. The effects of LPS (10 ng/mL) alone were reproduced with LPS (.1 ng/mL) plus heat-inactivated pooled normal human serum. Preincubation of PMN with anti-CD14 monoclonal antibodies prevented the effects of LPS+serum on the translocation of CD11b/CD18 receptors. These results demonstrate that LPS regulates CD11b/CD18 expression by inducing intracytoplasmic translocation of this receptor to azurophilic granules. This process involves activation of protein tyrosine kinase, and endosomal acidification contributes to the degradation of these receptors within azurophilic granules.

Acute-Phase Proteins↗
PubMed1994

Polymorphonuclear leukocyte dysregulation during the systemic inflammatory response syndrome.

Altered polymorphonuclear leukocyte (PMN) function is thought to contribute to organ dysfunction during the systemic inflammatory response syndrome (SIRS). To test this hypothesis, we evaluated whole blood PMN function adherent to fibronectin or laminin in patients with mild or severe acute pancreatitis as a paradigm for sirs. Whole-blood PMN intracellular H2O2 production, expression of CD32w (Fc gamma R II), CD16 (Fc gamma R III), and phagocytosis were performed using dichlorofluorescein diacetate, fluorescein isothiocyanate-labeled anti-CD32w, CD16, and serum-opsonized fluorescent microspheres. Group I (n x 7) represents normal control individuals; group II (n x 11) represents patients with mild acute pancreatitis. Group III (n x 15) represents critically ill patients with severe acute pancreatitis. Adherence of PMN from groups I and II to matrix proteins resulted in a 5% to 20% increase in each PMN function assayed whereas adherence of PMN from group III to matrix proteins resulted in 50% to 75% increases in each PMN function assayed. Pertussis toxin, pentoxifylline, and dibutyryl cyclic adenosine monophosphate (cAMP) each reduced group I-II H2O2 production and phagocytosis. Pentoxifylline and dibutyryl cAMP but not pertussis toxin reduced group III H2O2 production. Both intracellular H2O2 and phagocytosis assays from group III but not groups I-II showed exaggerated upregulation when exposed to NaF (4 mmol/L). Anti-interleukin-6 reduced the increase in intracellular H2O2 production in group III patients and significantly altered the exaggerated oxidative response to NaF. Longitudinal studies of group III whole-blood PMN showed persistent upregulation of intracellular H2O2 production in those patients whose hospital courses were complicated by multiple system organ failure. These results demonstrate abnormal whole blood PMN function during the systemic inflammatory response syndrome in the presence of fibronectin, or laminin and that this is mediated in part via a pertussis toxin insensitive altered guanosine triphosphate-binding protein.

Cell Adhesion↗
PubMed1994

Regulation of intracellular polymorphonuclear leukocyte Fc receptors by lipopolysaccharide.

Endotoxemia, in man, has been associated with an autooxidative reduction in the bioavailability of polymorphonuclear leukocyte receptors. The location and mechanisms of this phenomena have remained unclear; we investigated the effects of lipopolysaccharide (LPS) on intracellular Fc gamma receptor expression. Polymorphonuclear leukocytes (PMN) were incubated with LPS (10 ng/ml), permeabilized with saponin, followed by measurement of CD64, CD32w, and CD16 (Fc gamma RI, II, III) using 125I-monoclonal antibodies directed against these receptors. Exposure of permeabilized PMN to LPS significantly reduced intracellular Fc gamma receptor expression. PMN isolated from patients with chronic granulomatous disease or myeloperoxidase-specific deficiency did not exhibit this effect. Furthermore, specific inhibitors of components of the PMN oxidative burst (NaN3, 10 mM; L-alanine 30 mM) prevented the LPS-induced oxidative reduction in receptor expression. NADPH oxidase inhibition with diphenyleneiodonium also blocked the effect of LPS on intracellular Fc gamma receptor expression. The effects of LPS on intracellular PMN Fc gamma receptors were reproduced with monophosphoryl lipid A but required a 10 times greater concentration than LPS. Preadherence of PMN on fibronectin or arginine-glycine-aspartate-serine (RGDS), but not laminin, prevented the LPS-induced reduction in oxidative receptor expression. The effects of fibronectin/RGDS were blocked by actinomycin D and cycloheximide. Cross-linkage of intracellular Fc gamma receptors prior to exposure to LPS also prevented the LPS-induced oxidative reduction in receptor expression. These results demonstrate that an important pathophysiologic property of LPS is to induce an intracellular oxidative-derived reduction in Fc gamma receptor expression and that the biologically relevant proteins fibronectin and RGDS ameliorate this effect.

Cytoplasm↗