Maximal human neutrophil priming for superoxide production and elastase release requires p38 mitogen-activated protein kinase activation

Mechanosensitive traction force generation is regulated by the neutrophil activation state

The generation of traction forces by neutrophils regulates many crucial effector functions responsible for host defense, such as attachment, spreading, migration, phagocytosis, and NETosis. The activation state of the cell is a strong determinant of the functional efficacy of the neutrophil; however, the effect of activation on traction force production has not yet been determined experimentally. Previously, the mapping of cellular-generated forces produced by human neutrophils via a Traction Force Microscopy (TFM) method has required a three-dimensional imaging modality to capture out-of-plane forces, such as confocal or multiphoton techniques. A method newly developed in our laboratories can capture out-of-plane forces using only a two-dimensional imaging modality. This novel technique-combined with a topology-based single particle tracking algorithm and finite element method calculations-can construct high spatial frequency three-dimensional traction fields, allowing for traction forces in-plane and out-of-plane to the substrate to now be differentially visualized and quantified with a standard epifluorescence microscope. Here we apply this technology to determine the effect of neutrophil activation on force generation. Sepsis is a systemic inflammatory response that causes dysregulated neutrophil activation in vivo. We found that neutrophils from septic patients produced greater total forces than neutrophils from healthy donors and that the majority of this dysregulation occurred in-plane to the substrate. Ex vivo activation of neutrophils from healthy donors showed differential consequences depending on activation stimuli with mechanosensitive force decreases observed in some cases. These findings demonstrate the feasibility of epifluorescence-based microscopy in mapping traction forces to ask biologically significant questions regarding neutrophil function.

The effect of red-to-near-infrared (R/NIR) irradiation on inflammatory processes

Introduction: Near-infrared (NIR) and red-to-near-infrared (R/NIR) radiation are increasingly applied for therapeutic use. R/NIR-employing therapies aim to stimulate healing, prevent tissue necrosis, increase mitochondrial function, and improve blood flow and tissue oxygenation. The wide range of applications of this radiation raises questions concerning the effects of R/NIR on the immune system. Methods: In this review, we discuss the potential effects of exposure to R/NIR light on immune cells in the context of physical parameters of light. Discussion: The effects that R/NIR may induce in immune cells typically involve the production of reactive oxygen species (ROS), nitrogen oxide (NO), or interleukins. Production of ROS after exposure to R/NIR can either be inhibited or to some extent increased, which suggests that detailed conditions of experiments, such as the spectrum of radiation, irradiance, exposure time, determine the outcome of the treatment. However, a wide range of immune cell studies have demonstrated that exposure to R/NIR most often has an anti-inflammatory effect. Finally, photobiomodulation molecular mechanism with particular attention to the role of interfacial water structure changes for cell physiology and regulation of the inflammatory process was described. Conclusions: Optimization of light parameters allows R/NIR to act as an anti-inflammatory agent in a wide range of medical applications.

Bioassay-guided purification of sesquiterpenoids from the fruiting bodies of Fomitopsis pinicola and their anti-inflammatory activity

Twelve undescribed sesquiterpenoids, fomitopins A–L (1–12), were isolated via bioassay-guided purification from the bracket fungus Fomitopsis pinicola which has been reported to exhibit anti-microbial and anti-inflammatory activities.

The function of TRP channels in neutrophil granulocytes

Neutrophil granulocytes are exposed to widely varying microenvironmental conditions when pursuing their physiological or pathophysiological functions such as fighting invading bacteria or infiltrating cancer tissue. Examples for harsh environmental challenges include among others mechanical shear stress during the recruitment from the vasculature or the hypoxic and acidotic conditions within the tumor microenvironment. Chemokine gradients, reactive oxygen species, pressure, matrix elasticity, and temperature can be added to the list of potential challenges. Transient receptor potential (TRP) channels serve as cellular sensors since they respond to many of the abovementioned environmental stimuli. The present review investigates the role of TRP channels in neutrophil granulocytes and their role in regulating and adapting neutrophil function to microenvironmental cues. Following a brief description of neutrophil functions, we provide an overview of the electrophysiological characterization of neutrophilic ion channels. We then summarize the function of individual TRP channels in neutrophil granulocytes with a focus on TRPC6 and TRPM2 channels. We close the review by discussing the impact of the tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) on neutrophil granulocytes. Since neutrophil infiltration into PDAC tissue contributes to disease progression, we propose neutrophilic TRP channel blockade as a potential therapeutic option.

Oxidized LDL induced extracellular trap formation in human neutrophils via TLR-PKC-IRAK-MAPK and NADPH-oxidase activation

Neutrophil extracellular traps (NETs) formation was initially linked with host defence and extracellular killing of pathogens. However, recent studies have highlighted their inflammatory potential. Oxidized low density lipoprotein (oxLDL) has been implicated as an independent risk factor in various acute or chronic inflammatory diseases including systemic inflammatory response syndrome (SIRS). In the present study we investigated effect of oxLDL on NETs formation and elucidated the underlying signalling mechanism. Treatment of oxLDL to adhered PMNs led to a time and concentration dependent ROS generation and NETs formation. OxLDL induced free radical formation and NETs release were significantly prevented in presence of NADPH oxidase (NOX) inhibitors suggesting role of NOX activation in oxLDL induced NETs release. Blocking of both toll like receptor (TLR)-2 and 6 significantly reduced oxLDL induced NETs formation indicating requirement of both the receptors. We further identified Protein kinase C (PKC), Interleukin-1 receptor associated kinase (IRAKs), mitogen-activated protein kinase (MAPK) pathway as downstream intracellular signalling mediators involved in oxLDL induced NETs formation. OxLDL components such as oxidized phospholipids (lysophosphatidylcholine (LPC) and oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC)) were most potent NETs inducers and might be crucial for oxLDL mediating NETs release. Other components like, oxysterols, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were however less potent as compared to oxidized phospholipids. This study thus demonstrates for the first time that treatment of human PMNs with oxLDL or its various oxidized phopholipid component mediated NETs release, implying their role in the pathogenesis of inflammatory diseases such as SIRS.

Immobilized immune complexes induce neutrophil extracellular trap release by human neutrophil granulocytes via FcγRIIIB and Mac-1

Canonical neutrophil antimicrobial effector mechanisms, such as degranulation, production of reactive oxygen species, and release of neutrophil extracellular traps (NETs), can result in severe pathology. Activation of neutrophils through immune complexes (ICs) plays a central role in the pathogenesis of many autoimmune inflammatory diseases. In this study, we report that immobilized ICs (iICs), which are hallmarks of several autoimmune diseases, induce the release of NETs from primary human neutrophils. The iIC-induced NET formation was found to require production of reactive oxygen species by NADPH oxidase and myeloperoxidase and to be mediated by FcγRIIIb. Blocking of the β2 integrin macrophage-1 Ag but not lymphocyte function-associated Ag-1 abolished iIC-induced NET formation. This suggests that FcγRIIIb signals in association with macrophage-1 Ag. As intracellular signaling pathways involved in iIC-induced NET formation we identified the tyrosine kinase Src/Syk pathway, which downstream regulates the PI3K/Akt, p38 MAPK, and ERK1/2 pathways. To our knowledge, the present study shows for the first time that iICs induce NET formation. Thus, we conclude that NETs contribute to pathology in autoimmune inflammatory disorders associated with surface-bound ICs.

Phosphatase Wip1 negatively regulates neutrophil migration and inflammation

Neutrophils are critically involved in host defense and tissue damage. Intrinsic signal mechanisms controlling neutrophil activities are poorly defined. We found that the expression of wild-type p53-induced phosphatase 1 (Wip1) in mouse and human neutrophils was downregulated quickly after neutrophil activation through JNK-microRNA-16 pathway. Importantly, the Wip1 expression level was negatively correlated with inflammatory cytokine productions of neutrophils in sepsis patients. Wip1-deficient mice displayed increased bactericidal activities to Staphylococcus aureus and were hypersensitive to LPS-induced acute lung damage with increased neutrophil infiltration and inflammation. Mechanism studies showed that the enhanced inflammatory activity of neutrophils caused by Wip1 deficiency was mediated by p38 MAPK-STAT1 and NF-κB pathways. The increased migration ability of Wip1KO neutrophils was mediated by the decreased CXCR2 internalization and desensitization, which was directly regulated by p38 MAPK activity. Thus, our findings identify a previously unrecognized function of Wip1 as an intrinsic negative regulator for neutrophil proinflammatory cytokine production and migration through multiple signal pathways.

Effects of C-reactive protein on the neutrophil respiratory burst in vitro

This study determined the influence of physiologically relevant concentrations of C-reactive protein (CRP) on reactive oxygen species (ROS) production by neutrophils. Neutrophils from healthy individuals were incubated with soluble pentameric CRP prior to TLR stimulation with Fusobacterium nucleatum, or FcγR stimulation with IgG-opsonised Staphylococcus aureus or heat-aggregated IgG. ROS generation by unstimulated cells and those after stimulation were determined using luminol, isoluminol and lucigenin chemiluminescence, detecting predominantly intracellular hypochlorous acid (HOCl), extracellular hydrogen peroxide (detected as HOCl) and extracellular superoxide respectively. Baseline (unstimulated) neutrophil ROS generation and release was reduced compared with vehicle control by 10 µg/ml CRP. There was no consistent effect of CRP on FcγR-stimulated HOCl production, but the extracellular superoxide response was reduced by 10 µg/ml CRP. By contrast, CRP reduced intracellular (10 µg/ml) and extracellular (3 and 10 µg/ml) HOCl generation, but increased superoxide release (1-10 µg/ml) in response to TLR stimulation. Physiologically relevant concentrations of CRP inhibited baseline ROS generation and reduced FcγR-stimulated extracellular superoxide and TLR-stimulated HOCl release, suggesting that CRP may offer some degree of host protection from neutrophil-associated, low-level oxidative stress. However, CRP enhanced TLR-mediated superoxide release from neutrophils, potentially increasing oxidative stress but aiding host protection from infection.

Lipidomics analysis of mesenteric lymph after trauma and hemorrhagic shock

BACKGROUND

After trauma and hemorrhagic shock (T/HS), a variety of inflammatory mediators enter the systemic circulation through mesenteric lymph ducts, leading to acute lung injury and multiple-organ dysfunction syndrome. Recent studies have demonstrated that post-HS mesenteric lymph (PHSML) activates polymorphonuclear leukocytes (PMNs) and causes vascular endothelial cell and red blood cell dysfunction. Furthermore, PHSML contains proinflammatory mediators, such as biologically active lipids. The purpose of this study was to identify the lipid mediators in PHSML and plasma by liquid chromatography/electrospray ionization mass spectrometry and then estimate the biologic activities of the identified lipids on PMNs.

METHODS

PHSML was collected from male Sprague-Dawley rats undergoing trauma (laparotomy) plus HS (40 mm Hg, 30 minutes) or sham shock (SS). The lipids in PHSML and plasma were extracted using the methods of Bligh and Dyer, and liquid chromatography/electrospray ionization mass spectrometry was performed. The biologic activities (superoxide production and elastase release) of identified lipids on human PMNs were tested.

RESULTS

Phosphatidylcholine, lysophosphatidylcholine (LPC), phosphatidylethanolamine, lysophosphatidylethanolamine (LPE), and sphingomyelin were detected in the PHSML. Furthermore, linoleoyl, arachidonoyl, and docosahexaenoyl LPCs and LPEs significantly increased in the PHSML of the T/HS group as compared with those of the T/SS group. In the plasma, arachidonoyl and docosahexaenoyl LPCs of the T/HS group also significantly increased in comparison with that of the T/SS group. Linoleoyl and arachidonoyl LPCs and LPEs showed the priming activity on N-formyl-methionyl-leucyl-phenylalanine-activated PMNs. The elastase release was also induced by linoleoyl and arachidonoyl LPCs.

CONCLUSION

Mesenteric lymph after T/HS contains biologically active lipids, such as LPCs and LPEs with polyunsaturated fatty acids, which may be involved in the pathogenesis of acute lung injury/multiple-organ dysfunction syndrome.

Effects of subacute oral warfarin administration on peripheral blood granulocytes in rats

Warfarin affects mainly vitamin K dependent (VKD) processes, but the effects on some non-VKD-related activities such as tumor growth inhibition and mononuclear cell-mediated immune reactions were shown as well. In this study, the effect of subchronic (30 days) oral warfarin (0.35 mg/l and 3.5mg/l) intake on peripheral blood granulocytes in rats was investigated. Increase in prothrombin and partial thromboplastin time at high warfarin dose reflected its basic activity. Priming effect for respiratory burst was noted at both warfarin doses, while only high warfarin dose resulted in priming for adhesion, the rise in intracellular myeloperoxidase content/release and stimulation of nitric oxide production. Differential effects of high warfarin dose were noted on granulocyte cytokines IL-6 (lack of the effect), TNF-α (decreased release and mRNA expression) and IL-12 (increase in mRNA for IL-12 subunits p35 and p40). Changes in granulocytes seems not to rely on mitogen activated kinases p38 and ERK. Warfarin intake was associated with an increase in circulating IL-6, fibrinogen and haptoglobin and with changes in the activity of erythrocyte antioxidant enzymes superoxide dismutase and catalase. The effects of oral warfarin intake on peripheral blood granulocytes demonstrated in this study might be relevant for oral anticoagulant therapy strategies in humans.

Inflammatory response in multiple organs in a mouse model of acute alcohol intoxication and burn injury

This study characterized the inflammatory response after burn injury and determined whether ethanol (EtOH) intoxication at the time of burn injury influences this response. To accomplish this, male mice were gavaged with EtOH (2.9 g/kg) 4 hours before 12 to 15% TBSA sham or burn injury. Mice were killed on day 1 after injury; blood, small intestine, lung, and liver were collected to measure interleukin (IL)-6, IL-10, IL-18, and Monocyte chemotactic protein-1 (MCP-1) levels. In addition, neutrophil infiltration, myeloperoxidase activity, and edema formation were also measured in the small intestine, lung, and liver. There was no difference in the inflammatory markers in the small intestine, lung, and liver in mice receiving either sham or burn injury alone except IL-6 that was increased in all four tissue compartments after burn injury alone. However, when compared with EtOH or burn injury alone, EtOH combined with burn injury resulted in a significant increase in cytokines, neutrophil infiltration, myeloperoxidase activity, and edema in the small intestine, liver, and lung tissue. Furthermore, a significant increase in IL-6 and MCP-1 was observed in circulation after EtOH intoxication and burn injury compared with either EtOH intoxication or burn injury alone; no other cytokines were detected in circulation. These findings suggest that acute EtOH intoxication exacerbates the inflammatory response after burn injury.

Sulfur mustard primes human neutrophils for increased degranulation and stimulates cytokine release via TRPM2/p38 MAPK signaling

Sulfur mustard (2,2'-bis-chloroethyl-sulfide; SM) has been a military threat since the World War I. The emerging threat of bioterrorism makes SM a major threat not only to military but also to civilian world. SM injury elicits an inflammatory response characterized by infiltration of neutrophils. Although SM was reported to prime neutrophils, the mechanism has not been identified yet. In the present study, we investigated the mechanism of SM-induced priming in human neutrophils. SM increased [Ca(2+)](i) in human neutrophils in a concentration-dependent fashion. Transient receptor potential melastatin (TRPM) 2 inhibitors (clotrimazole, econazole and flufenamic acid) and silencing of TRPM2 by shRNA attenuated SM-induced [Ca(2+)](i) increase. SM primed degranulation of azurophil and specific granules in response to activation by fMLP as previously reported. SB203580, an inhibitor of p38 MAPK, inhibited SM-induced priming. Neither PD98057, an ERK inhibitor, nor SP600215, a JNK inhibitor, inhibited SM-induced priming. In addition, SM enhanced phosphorylation of NF-kB p65 and release of TNF-α, interleukin (IL)-6 and IL-8. SB203580 inhibited SM-induced NF-kB phosphorylation and cytokine release. These results suggest the involvement of TRPM2/p38 MAPK pathway in SM-induced priming and cytokines release in neutrophils.

Activation of the neutrophil respiratory burst by plasma from periodontitis patients is mediated by pro-inflammatory cytokines

AIM

To determine the effect of periodontitis patients' plasma on the neutrophil oxidative burst and the role of albumin, immunoglobulins (Igs) and cytokines.

MATERIALS AND METHODS

Plasma was collected from chronic periodontitis patients (n=11) and periodontally healthy controls (n=11) and used with/without depletion of albumin and Ig or antibody neutralization of IL-8, GM-CSF or IFN-α to prime/stimulate peripheral blood neutrophils, isolated from healthy volunteers. The respiratory burst was measured by lucigenin-dependent chemiluminescence. Plasma cytokine levels were determined by ELISA.

RESULTS

Plasmas from patients were significantly more effective in both directly stimulating neutrophil superoxide production and priming for subsequent formyl-met-leu-phe (fMLP)-stimulated superoxide production than plasmas from healthy controls (p<0.05). This difference was maintained after depletion of albumin and Ig. Plasma from patients contained higher mean levels of IL-8, GM-CSF and IFN-α. Individual neutralizing antibodies against IL-8, GM-CSF or IFN-α inhibited the direct stimulatory effect of patients' plasma, whereas the ability to prime for fMLP-stimulated superoxide production was only inhibited by neutralization of IFN-α. The stimulating and priming effects of control plasma were unaffected by antibody neutralization.

CONCLUSIONS

This study demonstrates that plasma cytokines may have a role in inducing the hyperactive (IL-8, GM-CSF, IFN-α) and hyper-reactive (IFN-α) neutrophil phenotype seen in periodontitis patients.

New properties of the soybean trypsin inhibitor: Inhibition of human neutrophil elastase and its effect on acute pulmonary injury

Seeds from legumes including the Gilcine max are known to be a rich source of protease inhibitors. The soybean Kunitz trypsin inhibitors (SKTIs) have been well characterised and have been found to exhibit many biological activities. However their effects on inflammatory diseases have not been studied to date. In this study, SKTI was purified using anion exchange chromatography using a Resource Q column. The purified protein was able to inhibit human neutrophil elastase (HNE) and bovine trypsin. Purified SKTI inhibited HNE with an IC(50) value of 8mug or 0.3nM. At this concentration SKTI showed neither cytotoxic nor haemolytic effects on human blood cell populations. SKTI showed no deleterious effects on organs, blood cells or the hepatic enzymes ALT and AST in the mouse model of acute systemic toxicity. Human neutrophils incubated with SKTI released less HNE than control neutrophils when stimulated with PAF or fMLP (83.1% and 70% respectively). These results showed that SKTI affected both pathways of elastase release by PAF and fMLP stimuli, suggesting that SKTI is an antagonist of fMLP/PAF receptors. In an in vivo mouse model of LPS acute lung injury, SKTI significantly suppressed the inflammatory effects caused by elastase in a dose-dependent manner. Histological sections stained by hematoxylin/eosin confirmed this decrease in inflammation. These results showed that SKTI could be used as a pharmacological agent for the therapy of many inflammatory diseases.

Anti-inflammatory effects of the extract of indigo naturalis in human neutrophils

ETHNOPHARMACOLOGICAL RELEVANCE

Indigo naturalis is used by traditional Chinese medicine to treat various inflammatory diseases.

AIM OF THE STUDY

Topical indigo naturalis ointment showed efficacy in treating psoriasis in our previous clinical studies. In this study, we investigated the anti-inflammatory effects of the extract of indigo naturalis (QD) and its main components indirubin, indigo, and tryptanthrin in human neutrophils.

MATERIALS AND METHODS

Superoxide anion (O2(.-)) generation and elastase release were measured by spectrophotometry. Some important signals including mitogen-activated protein kinase (MAPK), cAMP, and calcium were studied by Western blot analysis, an enzyme immunoassay, and spectrofluorometry.

RESULTS

QD significantly inhibited O2(.-) generation and elastase release in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-activated human neutrophils in a concentration-dependent fashion, while neither indirubin, indigo, nor tryptanthrin produced a comparable result. QD attenuated the FMLP-induced phosphorylation of extracellular regulated kinase, p38 MAPK, and c-Jun N-terminal kinase. Furthermore, QD inhibited calcium mobilization caused by FMLP. However, QD did not affect cellular cAMP levels. On the other hand, neither indirubin, indigo, nor tryptanthrin produced similar changes in human neutrophils.

CONCLUSIONS

Taken collectively, these findings indicate that QD, but not indirubin, indigo, or tryptanthrin, inhibited O2(.-) generation and elastase release in FMLP-induced human neutrophils, which was at least partially mediated by the inhibition of MAPK activation and regulation of calcium mobilization.

Neutrophil chemokines and their role in IL-18-mediated increase in neutrophil O2- production and intestinal edema following alcohol intoxication and burn injury

We examined the role of interleukin (IL)-18 and cytokine-induced neutrophil chemokines (CINC)-1 and CINC-3 in the neutrophil release of superoxide anion (O2-) and elastase following alcohol/ethanol (EtOH) and burn injury. Male rats (approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dl before approximately 12.5% total body surface area burn or sham injury. Immediately after injury, rats were administered with anti-rat IL-18 antibody (80 microg/kg) or isotype control. After 20 min, anti-IL-18 antibody-treated rats were given either recombinant (r) rat CINC-1 or CINC-3. On day 1 after injury, the combined insult of EtOH and burn injury caused a significant increase in neutrophil elastase and O2- production as well as an increase in neutrophil accumulation, myeloperoxidase activity, and edema in the intestine. Treatment of rats with anti-IL-18 antibody normalized the above parameters. However, administration of rCINC-1 in anti-IL-18 antibody-treated rats increased the above parameters to levels similar to those observed following EtOH and burn injury. In contrast, administration of rCINC-3 did not influence the above parameters except neutrophil elastase. These findings indicate that IL-18 and CINC-1 may independently modulate neutrophil tissue-damaging actions following EtOH and burn injury. However, the finding that the treatment of rats with anti-IL-18 antibodies inhibits CINC-1 and CINC-3 supports the notion that IL-18 plays a critical role in increased neutrophil tissue-damaging action following a combined insult of EtOH intoxication and burn injury.

Kinin B1 receptor activation turns on exocytosis of matrix metalloprotease-9 and myeloperoxidase in human neutrophils: involvement of mitogen-activated protein kinase family

During neutrophil activation and degranulation, MMP-9 and MPO are released into the extracellular space to propagate inflammatory disorders. As kinin peptides are major participants in acute inflammatory responses, and the G-protein-coupled B(1)R mediates the chemotaxis of human neutrophils, we examined the release of the neutrophil enzymes MMP-9 and MPO by the B(1)R agonist LDBK and determined the signaling pathways that may regulate this cellular effect. Cytochalasin-treated and -untreated neutrophils were suspended in HBSS and stimulated with a range concentration of LDBK for 5 min. Zymography and Western blotting revealed that LDBK induced the release of MMP-9 and MPO. The use of specific signaling transduction inhibitors showed that release of MMP-9 depended on ERK1/2 and p38 MAPKs, whereas release of MPO involved only the p38 cascade. Inhibition of the key steps in these pathways showed that the release of both enzymes depended on PKC and PI3K. Stimulation of neutrophils with LDBK produced phosphorylation of ERK1/2 and p38 MAPK, which was inhibited by B(1)R antagonists. The phosphorylated ERK1/2 MAPK translocated to the neutrophil nucleus, suggesting that transcription of new genes may follow activation of B(1)R. Our results demonstrate that in human neutrophils, activation of kinin B(1)R by LDBK initiates separate signaling cascades that trigger the release of MMP-9 and MPO from tertiary and primary granules, respectively, suggesting that the B(1)R plays a pivotal role in inflammatory disorders.

Impaired priming and activation of the neutrophil NADPH oxidase in patients with IRAK4 or NEMO deficiency

The NADPH oxidase (NOX), an oligomeric enzyme, plays a key role in polymorphonuclear neutrophil (PMN)-mediated host defense by producing cytotoxic superoxide anion (O(2)( )). Whereas in vitro and biochemical studies have examined the assembly and activation of this important host immune defense system, few studies have examined the function of NOX in human patients with primary immunodeficiency other than chronic granulomatous disease. We studied the activation of NOX in PMN from patients with two distinct immunodeficiencies, IL-1R-associated kinase (IRAK)4 deficiency and NF-kappaB essential modulator (NEMO or IkappaB kinase gamma) deficiency. We observed impaired O(2)( ) generation by LPS-treated and fMLP-activated IRAK4-deficient PMN that correlated with decreased phosphorylation of p47(phox) and subnormal translocation of p47(phox), p67(phox), Rac2, and gp91(phox)/Nox2 to the membranes indicating that TLR4 signaling to the NOX activation pathway requires IRAK4. NEMO-deficient PMN generated significantly less O(2)( ) in response to LPS-primed fMLP and translocated less p67(phox) than normal PMN, although p47(phox) and Rac2 translocation were normal. Generally, responses of NEMO-deficient cells were intermediate between IRAK4-deficient cells and normal cells. Decreased LPS- and fMLP-induced phosphorylation of p38 MAPK in both IRAK4- and NEMO-deficient PMN implicates additional signal transduction pathways in regulating PMN activation by LPS and fMLP. Decreased activation of NOX may contribute to the increased risk of infection seen in patients with IRAK4 and NEMO deficiency.

Heme oxygenase-1 protects against neutrophil-mediated intestinal damage by down-regulation of neutrophil p47phox and p67phox activity and O2- production in a two-hit model of alcohol intoxication and burn injury

Heme oxygenase-1 (HO-1) has been demonstrated to protect against tissue injury. Furthermore, HO-1 is also shown to be antioxidant. Our recent findings indicate that acute alcohol (EtOH) intoxication exacerbates postburn intestinal and lung tissue damage, and this was found to be neutrophil dependent. Because neutrophil-mediated tissue injury involves the release of superoxide anions (O(2)(-)), the present study examined the role of HO-1 in neutrophil O(2)(-) production following EtOH and burn injury. Furthermore, we investigated whether HO-1 antioxidant properties are mediated via modulation of p47(phox) and/or p67(phox) proteins. Male rats (approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL before burn or sham injury (approximately 12.5% total body surface area). Some rats were treated with HO-1 activator cobalt protoporphyrin IX chloride (Copp; 25 mg/kg body weight) at the time of injury. On day 1 after injury, we found that EtOH combined with burn injury significantly increased neutrophil O(2)(-) production and p47(phox) and p67(phox) activation and decreased caspase-3 activity and apoptosis. This was accompanied with a decrease in neutrophil HO-1 levels. The treatment of animals with HO-1 activator Copp normalized neutrophil HO-1, O(2)(-), p47(phox), and p67(phox) following EtOH and burn injury. The expression of caspase-3, however, was further decreased in Copp-treated sham and EtOH plus burn groups. Moreover, Copp treatment also prevented the increase in intestinal edema and permeability following EtOH and burn injury. Altogether, these findings provide a new insight into the mechanism by which HO-1 regulates neutrophil O(2)(-) production and protect the intestine from damage following EtOH and burn injury.

Acute alcohol intoxication potentiates neutrophil-mediated intestinal tissue damage after burn injury

This study examined whether acute alcohol (EtOH) intoxication before burn injury potentiates postburn intestinal tissue damage and whether neutrophils have any role in the damage under those conditions. Male rats ( approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL or with saline and received either approximately 12.5% or approximately 25% total body surface area (TBSA) burn or sham injury. Rats were killed at 4 or 24 h after injury, and various parameters were measured. As compared with sham animals, burn injury alone (regardless of size) resulted in a significant increase in intestinal tissue myeloperoxidase (MPO; an index of neutrophil infiltration) activity and IL-18 levels 4 h after injury. Furthermore, rats receiving 25% TBSA, but not 12.5%, burn exhibited intestine edema. The IL-18 and MPO activity were normalized at 24 h after injury in rats receiving 12.5% TBSA burn, whereas these parameters remained elevated at 24 h in rats with 25% burn. The presence of EtOH in rats at the time of burn injury exacerbated the levels of IL-18, MPO activity, and edema at 4 and 24 h after burn injury. Treatment of rats with anti-IL-18 antibodies or with antineutrophil antiserum prevented the increase in the above parameters after EtOH and burn injury, except that the depletion of neutrophils did not prevent the IL-18 increase. In summary, these findings suggest that acute EtOH intoxication exacerbates postburn intestinal tissue damage after burn injury, and that it is, in part, neutrophil mediated.

Inhibitory effects of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid on superoxide anion and elastase release in human neutrophils through multiple mechanisms

Reactive oxygen species and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. In this study, a cellular model in isolated human neutrophils was established to elucidate the anti-inflammatory functions of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid (PL3S), a clerodane diterpenoid from Formosan Polyalthia longifolia var. pendula. PL3S significantly inhibited the generation of superoxide anion and the release of elastase in formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP)-activated human neutrophils in a concentration-dependent fashion with IC50 values of 3.06+/-0.20 and 3.30+/-0.48 microM, respectively. PL3S did not affect cAMP-dependent pathway, and the inhibitory effect of PL3S was not reversed by protein kinase A inhibitor. PL3S did not display antioxidant or superoxide anion-scavenging ability, and it failed to alter the subcellular NADPH oxidase activity. PL3S concentration-dependently inhibited calcium mobilization caused by FMLP but not thapsigargin. Furthermore, PL3S attenuated the FMLP-induced protein kinase B (AKT) and p38 mitogen-activated protein kinase phosphorylation. However, PL3S had no effect on FMLP-induced phosphorylation of extracellular regulated kinase and c-Jun N-terminal kinase. In summary, these results indicate that the suppressive effects of PL3S on human neutrophil respiratory burst and degranulation are at least partly mediated by inhibition of calcium, AKT, and p38 signaling pathways.

Topical p38 MAPK inhibition reduces bacterial growth in an in vivo burn wound model

BACKGROUND

Although the inflammatory response is a prerequisite for wound healing, excessive activation of the innate immune system can induce epithelial cell damage and apoptosis, which may further compromise dermal integrity. In a noninfectious burn wound model, we previously demonstrated that topical inhibition of p38 MAPK, an important inflammatory signaling pathway, attenuated epithelial cell damage and apoptosis. We now question whether attenuating local inflammation would weaken bacterial wound resistance and compromise host defense.

METHODS

Rats received 30% total body surface area burn, and the wound was treated with topical application of a p38 MAPK inhibitor or vehicle. At 24 hours after injury, burn wounds were inoculated with Pseudomonas aeruginosa. At 48 hours postinjury, animals were sacrificed, and the burn wound was analyzed.

RESULTS

Inoculating burn wounds induced significant bacterial growth. Dermal inflammatory changes were markedly accentuated in the inoculated animals. Topical p38 MAPK inhibition reduced the proinflammatory cytokine expression in the burn wounds and neutrophil sequestration with or without bacterial inoculation. Interestingly, the bacterial wound growth was significantly attenuated in animals treated with topical p38 MAPK inhibitor.

CONCLUSIONS

Topical p38 MAPK inhibition attenuated wound inflammation without interfering with bacterial host defense. Attenuation of excessive burn wound inflammatory signaling may prevent secondary damage of the dermal barrier and reduce the growth of opportunistic pathogens.

Regulation of leukocyte degranulation by cGMP-dependent protein kinase and phosphoinositide 3-kinase: potential roles in phosphorylation of target membrane SNARE complex proteins in rat mast cells

We examined the roles of cGMP-dependent protein kinase (PKG) and PI3K in degranulation induced by fMLF and by FcepsilonRI cross-linking. In rat basophilic leukemia-2H3 cells expressing formyl peptide receptor, the PKG inhibitors KT5823 and Rp-8-Br-PET-cGMP, as well as the PI3K inhibitor LY294002, reduced agonist-stimulated beta-hexosaminidase release in a dose-dependent manner. These inhibitors also abolished vesicular fusion with the plasma membrane, as evidenced by diminished annexin V staining. Agonist-induced degranulation was completely blocked when LY294002 was applied together with one of the PKG inhibitors, suggesting an additive and possibly synergistic effect. In contrast, the PKG inhibitors did not affect fMLF-induced intracellular calcium mobilization and Akt phosphorylation. Likewise, LY294002 did not alter fMLF-induced elevation of intracellular cGMP concentration, and the inhibitory effect of LY294002 was not reversed by a cell-permeable analog of cGMP. Treatment with fMLF induced phosphorylation of soluble N-ethylmaleimide-sensitive factor-attachment protein (SNAP)-23, syntaxins 2, 4, and 6, and Monc18-3. The induced phosphorylation of SNAP-23 and syntaxins 2 and 4 was blocked by Rp-8-Br-PET-cGMP and LY294002. However, LY294002 was less effective in inhibiting Munc18-3 phosphorylation. The induced phosphorylation of syntaxin 6 was not effectively blocked by either Rp-8-Br-PET-cGMP or LY294002. Treatment of human neutrophils with the PKG inhibitors and LY294002 reduced enzyme release from primary, secondary, and tertiary granules. These results suggest that PKG and PI3K are involved in degranulation, possibly through phosphorylation of target membrane SNAP receptor proteins and their binding proteins.

INFLAMMATORY/CARDIOVASCULAR-METABOLIC RESPONSES IN A RAT MODEL OF BURN INJURY WITH SUPERIMPOSED INFECTION

Infection remains the major cause of morbidity and mortality in burn patients. Furthermore, the use of antibiotics in such patients has led to the prevalence of antibiotic-resistant microbial infections; one such infection in intensive care unit turns out to be caused by the enterococcal organisms. Our laboratory studies have used a rat model of bum injury and Enterococcus faecalis infection. Sprague-Dawley male rats ( approximately 250 g) were initially given an intragastric gavage of the antibiotic ciprofloxacin for 3 days. This procedure allowed for decontamination of intestine of gram-negative and some gram-positive organisms. The remainders of the gram-positive organisms were, to a large extent, Enterococci. After the decontamination procedure, rats were intra-abdominally inoculated with E. faecalis; inoculation involved preparation of sterilized rat fecal pellets impregnated with E. faecalis (10 colony-forming units) and their implants through a midline abdominal wall incision. Some of the rats that were implanted with the fecal pellets were subject to full-thickness skin bums ( approximately 30% total body surface area; 95 degrees C water for 7 s). Sham abdominal infection rats received a sterile pellet only; sham bum procedure consisted of exposing the skin to room temperature water. All sham and bum and/or E. faecalis infection procedures were carried out on rats under pentobarbital anesthesia. Inflammation and innate host defense-related responses were assessed via measurements of neutrophil effector responses, i.e., oxygen anion free radical (O2)/eIastase production, CD11b/CD18 expression, apoptosis, and tissue infiltration. Determining epithelial lactulose permeability, microvascular albumin leakage, and epithelial tight junction integrity assessed the status of intestinal function/structural derangements. The animals' metabolic and cardiovascular integrity was evaluated determining blood pH, p02, pC02, heart rate, respiratory rate, blood pressure, and cardiac output. Whereas the aforementioned measurements were carried out at 24 to 48 h postbum injury with and without the Enterococcal infection, animal mortality was determined for up to 5 days after the experimental injuries. The results of the studies indicated that whereas bum or E. faecalis infection alone did not produce significant mortality, the dual insult with bum and E. faecalis infection resulted in significant animal death accompanied by relatively more profound metabolic and cardiovascular derangements. Inappropriately heightened neutrophil effector responses were present with bum alone as well as with the dual bum and infection complications. These studies suggest that animal models of bum injury with Enterococcal infection complications simulate the adverse outcomes bum patients infected with Enterococcal organisms.

PEPTIDOGLYCAN OF STAPHYLOCCUS AUREUS INDUCES ENHANCED LEVELS OF MATRIX METALLOPROTEINASE-9 IN HUMAN BLOOD ORIGINATING FROM NEUTROPHILS

Enhanced plasma levels of matrix metalloproteinase 9 (MMP-9) detected in patients with severe sepsis are thought to contribute to the development of organ dysfunction in endotoxemia. We have recently reported that peptidoglycan, the major wall component of gram-positive bacteria, increases MMP-9 levels in lung and liver and organ injury in the rat. Thus far, it is unclear whether MMP-9 is part of the septic response to peptidoglycan in human blood. The aim of the present study was to examine the regulation of MMP-9 by peptidoglycan in human leukocytes. The addition of peptidoglycan to whole human blood caused enhanced levels of MMP-9 after 1 h of incubation (306 vs. 75 ng/mL, P < or = 0.05) and onward, as measured by enzyme-linked immunoabsorbant assay. In neutrophil cultures, MMP-9 values increased significantly after 30 min of incubation with peptidoglycan (242 vs. 121 ng/mL, P < or = 0.05), whereas muramyl dipeptide had no effect. In contrast, adherent monocytes released insignificant amounts of MMP-9. To examine whether the released MMP-9 resulted from de novo synthesis, intracellular and secreted MMP-9 was measured during stimulation of neutrophils. The total MMP-9 values (the sum of intracellular and secreted MMP-9) before and after stimulation were mainly unaltered. The enhanced MMP-9 levels induced by peptidoglycan was attenuated by inhibitors of p38 mitogen-activated protein kinases (MAPK), (SB202190, 25 microM) and ERK1/2 (PD98059, 25 microM) and inhibitors of Src Tyrosine kinase (PP2, 5 microM) and PI3-K (LY294002, 25 microM).

Optimisation of a human neutrophil elastase assay and investigation of the effect of sesquiterpene lactones

Neutrophil granulocytes are effector cells in innate and humoral immunity. They are involved in inflammatory processes by releasing pro-inflammatory enzymes, such as the human neutrophil elastase (HNE). We here report an optimisation of an HNE release assay using microplates. Special attention has been directed to overcome the often observed activation of neutrophils during isolation from fresh blood. This so-called basal stimulation can take place without addition of external stimulants and can cause severe problems during the assay. We demonstrated that bovine serum albumin (BSA), lipopolysaccharide (LPS), use of different blood donors, heparin and ethylenediaminetetraacetic acid (EDTA) do not cause basal stimulation, but may be due to mechanical stress and the immune system of the blood donor. Here, the number of eosinophils may play a role in the induction of activation. Basal stimulation was overcome when a hypertonic solution, such as sucrose- with N-(2-hydroxyethyl)-piperazine-N'-2-ethanesulfonic acid (HEPES) buffer, was used during centrifugation and the isolated granulocytes were left in phosphate buffered saline (PBS) for 30 min before stimulation. Sesquiterpene lactones (SLs), known for their anti-inflammatory activity were used for evaluation of the assay and were observed to inhibit HNE release at micromolar concentrations. Whereas N-formyl-methionyl-leucylphenylalanine (fMLP), platelet-activating factor (PAF) and basal stimulation resulted in similar IC50 values, phorbol-12-myristate-13-acetate (PMA) as a stimulant needed higher concentrations of SLs. The molecular inhibitory mechanism of SLs is discussed.

Dapsone suppresses human neutrophil superoxide production and elastase release in a calcium-dependent manner

BACKGROUND

Dapsone (4,4'-diaminodiphenyl sulphone) is a powerful therapeutic tool in many skin diseases including neutrophilic dermatoses. The drug has an outstanding therapeutic efficacy against many skin diseases characterized by neutrophil-rich infiltrates; however, mechanisms of its action are poorly understood.

OBJECTIVES

We investigated the effects of dapsone on respiratory and secretory functions of human neutrophils triggered by the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), the physiological agonist C5a, and phorbol myristate acetate (PMA).

METHODS

Human neutrophils were isolated from venous blood obtained from healthy donors. We detected extracellular production of superoxide (O(2) (-)) by cytochrome C reduction assay, and intracellular production of O(2) (-) by flow cytometry. Neutrophil elastase release was measured by the cleavage of the specific elastase substrate N-methoxysuccinyl-Ala-Ala-Pro-Val-p-nitroanilide. Measurement of cytosolic free calcium concentration was performed using the calcium-reactive fluorescence probe, Fluo-3.

RESULTS

Dapsone suppressed intra- and extracellular production of O(2) (-) and elastase release triggered by fMLP and C5a, but not by PMA. Both fMLP and C5a signalled the above pathways by inducing calcium influx, but PMA functions bypassed calcium influx. Dapsone was capable of antagonizing the induction of calcium influx.

CONCLUSIONS

These findings suggest that one mechanism of the anti-inflammatory action of dapsone is inhibition of calcium-dependent functions of neutrophils including release of tissue-damaging oxidants and proteases in the affected skin.

A serine proteinase inhibitor isolated from Tamarindus indica seeds and its effects on the release of human neutrophil elastase

Proteinaceous inhibitors with high inhibitory activities against human neutrophil elastase (HNE) were found in seeds of the Tamarind tree (Tamarindus indica). A serine proteinase inhibitor denoted PG50 was purified using ammonium sulphate and acetone precipitation followed by Sephacryl S-300 and Sephadex G-50 gel filtration chromatographies. Inhibitor PG50 showed a Mr of 14.9 K on Sephadex G-50 calibrated column and a Mr of 11.6 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PG50 had selective activity while cysteine proteinases (papain and bromelain) and serine proteinases (porcine pancreatic elastase and bovine chymotrypsin) were not inhibited, it was strongly effective against serine proteinases such as bovine trypsin and isolated human neutrophil elastase. The IC50 value was determined to be 55.96 microg.mL-1. PG50 showed neither cytotoxic nor haemolytic activity on human blood cells. After pre-incubation of PG50 with cytochalasin B, the exocytosis of elastase was initiated using PAF and fMLP. PG50 exhibited different inhibition on elastase release by PAF, at 44.6% and on release by fMLP, at 28.4%. These results showed that PG50 preferentially affected elastase release by PAF stimuli and this may indicate selective inhibition on PAF receptors.

Role of PDE4 in superoxide anion generation through p44/42MAPK regulation: a cAMP and a PKA-independent mechanism

We investigated the generation of reactive oxygen species (ROS) from bronchoalveolar lavage (BAL) cells of either control or LPS-exposed rats and the effects of PDE4 inhibitors on ROS production. The PDE4 inhibitors, rolipram and Ariflo (cilomilast, SB 207499) dose-dependently (0.1-10 microm) inhibited fMLP-induced superoxide anion (O(2)(*-)) production (IC(50)s: 0.03 and 0.55 microm, respectively) in BAL cells of Wistar rats collected 3 h after an LPS-aerosol (200 micrograms ml(-1), 1 h). These BAL contained 85-95% neutrophils (BAL cells enriched in neutrophils). In contrast, BAL cells collected at the end of the challenge contained only macrophages and in these conditions, rolipram and Ariflo (0.1-10 microm) could only inhibit 25 and 45% of fMLP-induced O(2)(*-) release, respectively. We also observed that the inhibition of p44/42(MAPK) by PD98059 (1-10 microm) increased O(2)(*-) release by BAL cells enriched in neutrophils, but not by macrophages, and prevented the inhibition of O(2)(*-) production induced by PDE4 inhibitors. Western blot analysis showed that PDE4 inhibitors strongly activated p44/42(MAPK) in BAL cells enriched in neutrophils but not in macrophages. And in these cells, PDE4 and p44/42(MAPK) were co-immunoprecipitated by a polyclonal anti-PDE4 antibody. The following cell permeable-cAMP analogues, dbcAMP (10 microm-1 mm), 8-CPT-cAMP (1 mm) and 8-pMeOPT-2'-O-Me-cAMP (0.5 mm), could not reduce fMLP-induced O(2)(*-) production and both PKA inhibitors, PKA inhibitor 14-22 amide myristoylated (50 nm-1 microm) and H-89 (100 nm-1 microm), did not affect the decrease of O(2)(*-) release induced by PDE4 inhibitors in BAL cells enriched in neutrophils. These data suggest that PDE4 inhibitors decreased fMLP-induced O(2)(*-) release in BAL cells enriched in neutrophils but not in macrophages, through p44/42(MAPK) activation by a cAMP- and a PKA-independent mechanism.

Primary granule release from human neutrophils is potentiated by soluble fibrinogen through a mechanism depending on multiple intracellular signaling pathways

N-Formyl-methionyl-leucyl-phenylalanine (fMLP) is a potent activator of neutrophil degranulation. The intracellular signaling mechanisms involved in the potentiating effect of fibrinogen on fMLP-induced primary granule release from human neutrophils were investigated. Fibrinogen caused a significant leftward shift of the concentration-response curve of fMLP-induced elastase release. An antibody against Mac-1 (CD11b/CD18) prevented the potentiating effect of fibrinogen, suggesting that soluble fibrinogen potentiates fMLP-induced degranulating effect by a mechanism mediated by the integrin Mac-1. Fibrinogen enhanced fMLP-induced tyrosine phosphorylation in human neutrophils and markedly enhanced the phosphorylation of mitogen-activated protein kinases (MAPK) caused by fMLP. However, U0126, an inhibitor of p44/42 MAPK activation, or SB-203580, an inhibitor of p38 MAPK, did not alter the effect of fibrinogen on fMLP-induced elastase release. Wortmannin, a phosphatidylinositol 3-kinase (PI3K) kinase inhibitor, and genistein, a nonspecific tyrosine kinase inhibitor, strongly inhibited fMLP-induced elastase release both in the presence and in the absence of fibrinogen. An Akt/PKB inhibitor failed to alter the potentiating effect of fibrinogen, suggesting that the effect of fibrinogen is mediated by Akt-independent pathways. Go6976, an inhibitor of classical PKC isoforms, caused a significant inhibition of fMLP-induced elastase release in the presence or absence of fibrinogen, while nonselective inhibitors of PKC, Ro 31-8220, GF-109203X, and staurosporine, caused potentiation of fMLP-induced elastase release. We conclude that fibrinogen potentiation of primary granule release induced by fMLP is mediated by the integrin CD11b/CD18 through pathways dependent on PI3K and tyrosine kinases, but other regulatory mechanisms may be also involved.

Distinct ligand-dependent roles for p38 MAPK in priming and activation of the neutrophil NADPH oxidase

In response to certain cytokines and inflammatory mediators, the activity of the neutrophil NADPH oxidase enzyme is primed for enhanced superoxide production when the cells receive a subsequent oxidase-activating stimulus. The relative role of p38 MAPK in the priming and activation processes is incompletely understood. We have developed a 2-step assay that allows the relative contributions of p38 MAPK activity in priming to be distinguished from those involved in oxidase activation. Using this assay, together with in vitro kinase assays and immunochemical studies, we report that p38 MAPK plays a critical role in TNFalpha priming of the human and porcine NADPH oxidase for superoxide production in response to complement-opsonized zymosan (OpZ), but little, if any, role in neutrophil priming by platelet-activating factor (PAF) for OpZ-dependent responses. The OpZ-mediated activation process per se is independent of p38 MAPK activity, in contrast to oxidase activation by fMLP, where 70% of the response is eliminated by p38 MAPK inhibitors regardless of the priming agent. We further report that incubation of neutrophils with TNFalpha results in the p38 MAPK-dependent phosphorylation of a subpopulation of p47(phox) and p67(phox) molecules, whereas PAF priming results in phosphorylation only of p67(phox). Despite these phosphorylations, TNFalpha priming does not result in significant association of either of these oxidase subunits with neutrophil membranes, demonstrating that the molecular basis for priming does not appear to involve preassembly of the NADPH oxidase holoenzyme/cytochrome complex prior to oxidase activation.

The effect of sesquiterpene lactones on the release of human neutrophil elastase

Sesquiterpene lactones (SLs) are natural products responsible for the anti-inflammatory activity of a variety of medicinal plants, mainly from the Asteraceae family. Here, we investigated whether they also influence the process of exocytosis of pro-inflammatory enzymes, such as the human neutrophil elastase (HNE). Altogether, eight structurally different SLs from the eudesmanolide, guaianolide, pseudoguaianolide, and germacranolide type were studied. Neutrophils were isolated from fresh human blood. After pre-incubation with different concentrations of the respective SL and cytochalasin B, the exocytosis of elastase was initiated either by platelet activating factor or N-formyl-methionyl-leucyl-phenylalanine. Inhibition of HNE release was measured by p-nitroaniline formation. The SLs exhibited an inhibitory effect on elastase release from neutrophils challenged either by platelet activating factor or N-formyl-methionyl-leucyl-phenylalanine. Concentration-response curves were recorded and the IC(50) values ranged from 2 to 30 microM. Studies on isolated HNE showed that a selective direct inhibition on HNE can be excluded. Interestingly, the inhibitory activity did not correlate with the number of alpha,beta-unsaturated carbonyl functions. The structure-activity relationship and the molecular mechanism are discussed.

Mitogen-activated protein kinases in the intensive care unit: prognostic potential

OBJECTIVE

To evaluate the prognostic significance of the activational status of p38, specifically progression to multiple organ dysfunction syndrome (MODS), in a group of severely injured trauma patients.

SUMMARY BACKGROUND DATA

To date, therapeutic manipulation of the host immunoinflammatory response has not affected the outcome of patients with MODS. A major concern is the inability to identify the patient most at risk so as to enable early intervention.

METHODS

Nineteen trauma patients underwent bronchoalveolar lavage (BAL). Cells obtained were plated, stimulated with lipopolysaccharide (LPS), and then harvested at varying time points after stimulation. p38 was evaluated by Western blot.

RESULTS

Nineteen patients were categorized into two groups according to baseline and LPS-stimulated p38 activation in cells obtained by BAL. Group 1 demonstrated a 10-fold increase in p38 activation with LPS treatment over unstimulated controls. Group 2 had high baseline levels of p38 that were unresponsive to subsequent LPS stimulation. Both groups were similar with respect to age, gender, shock (systolic blood pressure < 90), Injury Severity Score, APACHE II, lactate levels, base deficit, blood transfusions, and the cell differential of BAL fluid. However, patients in group 2 had a greater incidence of progression to MODS as defined by the Marshall MOD score, a longer duration of mechanical ventilation, a longer stay in the intensive care unit, and a longer overall hospital stay than group 1.

CONCLUSIONS

These results demonstrate the prognostic significance of p38 activation in predicting outcome in critically ill trauma patients. Furthermore, these results demonstrate that trauma populations identical by current scoring systems contain a mixture of patients with markedly different outcomes as identified by p38 activation. Measurement of p38 may enable early identification of a subgroup of patients at increased risk for MODS to permit effective therapeutic intervention.

Inhibition of p38 mitogen-activated protein kinase: dose-dependent suppression of leukocyte and endothelial response after endotoxin challenge in humans

OBJECTIVE

We studied the activity of a single oral dose of RWJ-67657, a synthetic p38 mitogen-activated protein kinase inhibitor, in preventing dual leukocyte/endothelial activation after endotoxin infusion in healthy volunteers.

DESIGN

Prospective placebo-controlled study.

SETTING

Intensive care unit at a university medical center.

SUBJECTS

Twenty-one healthy male volunteers.

INTERVENTIONS

Endotoxin (4 ng/kg) as a 1-min infusion. According to randomization, the volunteers received placebo (n = 6) or 1400 mg (n = 4), 700 mg (n = 6), or 350 mg (n = 5) of RWJ-67657.

MEASUREMENTS AND MAIN RESULTS

Neutrophil activation was investigated by analyzing the extent of membrane expression of adhesion markers by calibrated flow cytometry. Circulating intercellular adhesion molecule-1 and E-selectin were measured by enzyme-linked immunosorbent assays. The endotoxin-induced shedding of L-selectin was diminished in a dose-dependent manner (p <.0001). High-dose RWJ-67657 prevented up-regulation of the integrins CD11b (p <.01) and CD 66b (p <.01) on neutrophils. The endotoxin-induced increase in circulating intercellular adhesion molecule-1 and circulation E-selectin was almost completely prevented by high-dose RWJ-67657.

CONCLUSION

A single oral dose of RWJ-67657 prevented neutrophil and endothelial activation after endotoxin infusion.

Acute hypoxemia in humans enhances the neutrophil inflammatory response

The neutrophil (PMN) is regarded as a key component in the hyperinflammatory response known as the systemic inflammatory response syndrome. Acute respiratory distress syndrome (ARDS) and subsequent multiple organ failure (MOF) are related to the severity of this hyperinflammation. ICU patients who are at highest risk of developing MOF may have acute hypoxic events that complicate their hospital course. This study was undertaken to evaluate the effects of acute hypoxia and subsequent hypoxemia on circulating PMNs in human volunteers. Healthy subjects were exposed to a changing O2/N2 mixture until their O2 saturation (SaO2) reached a level of 68% saturation. These subjects were then exposed to room air and then returned to their baseline SaO2. PMNs were isolated from pre- and post-hypoxemic arterial blood samples and were then either stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or PMA alone, or they were primed with L-alpha-phosphatidylcholine, beta-acetyl-gamma-O-alkyl (PAF) followed by fMLP activation. Reactive oxygen species generation as measured by superoxide anion production was enhanced in primed PMNs after hypoxemia. Protease degranulation as measured by elastase release was enhanced in both quiescent PMNs and primed PMNs after fMLP activation following the hypoxemic event. Adhesion molecule upregulation as measured by CD11b/CD18, however, was not significantly changed after hypoxemia. Apoptosis of quiescent PMNs was delayed after the hypoxemic event. TNFalpha, IL-1, IL-6, and IL-8 cytokine levels were unchanged following hypoxemia. These results indicate that relevant acute hypoxemic events observed in the clinical setting enhance several PMN cytotoxic functions and suggest that a transient hypoxemic insult may promote hyperinflammation.

The involvement of L-gamma-glutamyl-L-cysteinyl-glycine (glutathione/GSH) in the mechanism of redox signaling mediating MAPK(p38)-dependent regulation of pro-inflammatory cytokine production

Redox regulation of mitogen-activated protein kinase (MAPK(p38))-mediated pro-inflammatory cytokine production is not well characterized in the alveolar epithelium. It was hypothesized that the involvement of the MAPK(p38) pathway in regulating lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-alpha and interleukin-6 secretion is redox-sensitive and affected by NAC, an antioxidant and a precursor of glutathione, and L-buthionine-(S,R)-sulfoximine, an irreversible inhibitor of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in GSH biosynthesis. Exposure of fetal alveolar type II epithelial cells to Escherichia coli-derived LPS induced, in a time-dependent manner, the phosphorylation/activation of MAPK(p38) (peak at 15min). In addition, LPS up-regulated the phosphorylation of MAPK(p38) in a dose-dependent manner. The effect of LPS on the MAPK(p38) pathway was associated with the activation of MAPK-activated protein kinase, which phosphorylated the small 27kDa heat-shock protein (Hsp27). LPS induced the phosphorylation of Hsp27 in a time- and dose-dependent manner. Selective blockage of the MAPK(p38) pathway by a pyridinyl-imidazole (SB-203580) abrogated LPS-induced release of TNF-alpha and IL-6. Pre-treatment with NAC reduced LPS-mediated secretion of TNF-alpha and IL-6. Incubation of cells with NAC induced intracellular accumulation of GSH, but reduced the concentration of GSSG. On the other hand, pre-treatment with BSO augmented LPS-mediated secretion of TNF-alpha and IL-6. In addition, BSO induced intracellular accumulation of GSSG, but reduced the concentration of GSH. Whereas NAC blocked the phosphorylation/activation of MAPK(p38), BSO amplified the LPS-mediated effect on MAPK(p38). These results indicated that intracellular redox signaling plays an important role in regulating LPS-induced activation of the MAPK(p38) pathway and MAPK(p38)-mediated regulation of LPS-dependent inflammatory cytokine production in the alveolar epithelium.

Redox/ROS regulation of lipopolysaccharide-induced mitogen-activated protein kinase (MAPK) activation and MAPK-mediated TNF-alpha biosynthesis

Redox and ROS regulation of MAPK-mediated TNF-alpha biosynthesis is not well characterized. It was hypothesized that the involvement of the MAPK pathway in regulating LPS-mediated TNF-alpha secretion is redox-dependent, NF-kappaB-sensitive and attenuated by N-acetyl-L-cysteine (NAC) and other antioxidants. In alveolar epithelial cells, LPS induced a time- and dose-dependent phosphorylation of MAPK(p38). This was associated with the activation of MAPK-activated protein kinase, which phosphorylated the small heat-shock protein, Hsp27. MAPK(p38) inhibition (SB-203580) abrogated LPS-induced TNF-alpha production. MAPK(ERK) blockade (PD-98059) attenuated TNF-alpha secretion, an effect synergistically amplified in the presence of SB-203580. Regulation of NF-kappaB by selective inhibitors revealed that this pathway is partially involved in regulating LPS-mediated TNF-alpha secretion. Whereas the proteasome inhibitor, MG-132, had no effect on LPS-mediated TNF-alpha production, CAPE, sulfasalazine and SN-50, a cell-permeant NF-kappaB inhibitor, attenuated but did not abrogate TNF-alpha biosynthesis. LPS up-regulated ROS, an effect abrogated by 4'-hydroxy-3'-methoxy-acetophenone and NAC, which reduced TNF-alpha secretion, induced the accumulation of GSH, reduced the concentration of GSSG, and blockaded the phosphorylation/activation of MAPK(p38) pathway. ROS induced MAPK(p38) phosphorylation and selective antioxidants, including the permeant GSH precursor, gamma-GCE, reduced ROS-dependent MAPK(p38) phosphorylation. These results indicate that the MAPK pathway and MAPK-mediated regulation of TNF-alpha production is redox-dependent, GSH-mediated and requires, at least in part, a NF-kappaB/ROS-sensitive mechanism.

Differential vulnerability to oxidative stress in rat cardiac myocytes versus fibroblasts

OBJECTIVES

This study was designed to test the hypothesis that cardiac myocytes have greater vulnerability to oxidative stress compared with cardiac fibroblasts.

BACKGROUND

The function of cardiac myocytes differs from that of fibroblasts in the heart, but differences in their response to oxidative stress have not been extensively studied.

METHODS

Cardiomyocytes and fibroblasts from F344 neonatal rat hearts were cultured and exposed to different concentrations of hydrogen peroxide (H(2)O(2)) and menadione (superoxide generator). The mitogen-activated protein kinase (MAPK) proteins were assayed after oxidative stress; cell death was determined by trypan blue staining and deoxyribonucleic acid (DNA) ladder electrophoresis.

RESULTS

The cardiac myocytes were significantly more vulnerable than the fibroblasts to oxidative damage, showing substantial DNA fragmentation and consistently poor cell survival after exposure to H(2)O(2) (100 to 800 microM), while the cardiac fibroblasts demonstrated little or no DNA fragmentation, and superior cell survival rates both over time (from 1 to 72 h after 100 microM) and across increasing doses of H(2)O(2) (100 to 800 microM). The p42/44 extracellular signal-regulated kinases were phosphorylated in both cell types after exposure to H(2)O(2), but significantly more in cardiac fibroblasts. However, p38 MAPK and c-jun NH(2)-terminal kinase were phosphorylated more in the cardiac myocytes compared to cardiac fibroblasts. This was also the case after exposure to menadione.

CONCLUSION

Taken together, these results suggest that oxidative stress causes greater injury and cell death in cardiac myocytes compared with cardiac fibroblasts. It is possible that the signaling differences via the MAPK family may partly mediate the observed differences in vulnerability and functional outcomes of the respective cell types.

Macrophage cyclooxygenase expression, immunosuppression, and cardiopulmonary dysfunction after blunt chest trauma

BACKGROUND

Two series of experiments were performed in swine who received severe blunt chest trauma. The goals were to determine the time course of constitutive and inducible cyclooxygenase (COX) isozyme expression in pulmonary macrophages (Mphis), and to determine whether COX expression and cardiopulmonary dysfunction were altered when neutrophils (PMNs) were pharmacologically depleted with cyclophosphamide (CYC).

METHODS

In series 1 (n = 17), anesthetized, mechanically ventilated swine were subjected to right chest trauma via captive bolt gun, hemorrhage, and a 60-minute shock period. In series 2 (n = 41), CYC (50 mg/kg intravenously) was administered 4 days before trauma, and the shock period was shortened to 30 minutes. In both series, hemodynamic support and supplemental oxygen were provided for an additional 60 to 90 minutes after shock. Mphis were isolated from serial bilateral bronchoalveolar lavages (BALs) and COX protein expression was measured with Western blots.

RESULTS

In series 1, death occurred in 11 of 17. In survivors, Mphi COX-1 peaked at > 100 times baseline in both right BAL and left BAL by 60 minutes (before resuscitation). Changes in Mphi COX-2 were minimal. In series 2, before trauma, CYC (n = 16) reduced circulating and BAL PMNs by > 90% relative to control (n = 25, both p < 0.05) with no complicating side effects. After trauma, death occurred in 11 of 25 controls versus 9 of 16 with CYC. In survivors, PaO2/FIO2 was < 250 and PaCO2 was 25% higher on constant minute ventilation, indicating mismatched ventilation/perfusion; both changes were reduced with CYC (p < 0.05). In controls, bilateral histologic damage included edema, alveolar hemorrhage, and interstitial infiltrates. These changes were reduced by one third with CYC (p = 0.08). Trauma-induced changes in BAL protein, BAL elastase, or Mphi COX expression were not lessened by CYC.

CONCLUSION

After unilateral chest trauma, Mphi COX-1, not COX-2, is induced bilaterally and before fluid resuscitation; CYC prevented PMN infiltration and attenuated structural and functional changes after resuscitation, which suggests that PMNs have a role in the pathogenic mechanism of secondary lung injury; Mphi COX expression and other injury markers were not altered by CYC; and since Mphis continued to express proinflammatory COX protein even after pretreatment with a powerful nonspecific immunosuppressant, and since there is residual alveolar capillary damage even in the absence of PMNs, it is logical to conclude that no single cell type or mediator is a practical therapeutic target and that novel resuscitation strategies must address multiple elements in the inflammatory cascade.