Mechanisms and consequences of phagocyte adhesion to endothelium

ERK1/2 Has Divergent Roles in LPS-Induced Microvascular Endothelial Cell Cytokine Production and Permeability

ABSTRACT

Endothelial cells play a major role in inflammatory responses to infection and sterile injury. Endothelial cells express Toll-like receptor 4 (TLR4) and are activated by LPS to express inflammatory cytokines/chemokines, and to undergo functional changes, including increased permeability. The extracellular signal-regulated kinase 1/2 (ERK1/2) mediates pro-inflammatory signaling in monocytes and macrophages, but the role of ERK1/2 in LPS-induced activation of microvascular endothelial cells has not been defined. We therefore studied the role of ERK1/2 in LPS-induced inflammatory activation and permeability of primary human lung microvascular endothelial cells (HMVEC). Inhibition of ERK1/2 augmented LPS-induced IL-6 and vascular cell adhesion protein (VCAM-1) production by HMVEC. ERK1/2 siRNA knockdown also augmented IL-6 production by LPS-treated HMVEC. Conversely, ERK1/2 inhibition abrogated permeability and restored cell-cell junctions of LPS-treated HMVEC. Consistent with the previously described pro-inflammatory role for ERK1/2 in leukocytes, inhibition of ERK1/2 reduced LPS-induced cytokine/chemokine production by primary human monocytes. Our study identifies a complex role for ERK1/2 in TLR4-activation of HMVEC, independent of myeloid differentiation primary response gene (MyD88) and TIR domain-containing adaptor inducing IFN-β (TRIF) signaling pathways. The activation of ERK1/2 limits LPS-induced IL-6 production by HMVEC, while at the same time promoting HMVEC permeability. Conversely, ERK1/2 activation promotes IL-6 production by human monocytes. Our results suggest that ERK1/2 may play an important role in the nuanced regulation of endothelial cell inflammation and vascular permeability in sepsis and injury.

Pulmonary function changes in rats with taurocholate-induced pancreatitis are attenuated by pretreatment with melatonin

Melatonin is a free radical scavenger and broad-spectrum antioxidant with immunomodulatory effects. We studied the effects of melatonin on changes in lung function, oxidative/nitrosative stress, and inflammatory cell sequestration in an acute pancreatitis (AP)-associated lung inflammation model. Acute pancreatitis was induced by injection of 5% sodium taurocholate into the pancreatic duct of rats. Animals were randomized into control, AP, and a melatonin pretreatment (10 mg/kg)/AP group. Functional residual capacity (FRC), lung compliance (Cchord), expiratory flow rate at 50% (FEF50), airway resistance index (RI), and peak expiratory flow rate (PEF) were evaluated. White blood cell count (WBC) and hydrogen peroxide, lung lavage fluid WBC, methylguanidine, protein, lactic dehydrogenase (LDH), nitric oxide (NO), and leukotriene B4 (LTB4) levels were determined. Lung wet-to-dry weight ratio, peroxynitrite, and inducible nitric oxide synthase (NOS) mRNA and protein were measured. AP induction resulted in reductions in FRC, Cchord, FEF50, and PEF, and increase in RI and lung wet-to-dry weight ratio. Blood and lung lavage fluid WBC, lavage fluid LDH, protein, and blood hydrogen peroxide also increased. Levels of hydroxyl radicals, nitric oxide, and LTB4 in lung lavage fluid, inducible NOS mRNA, protein expression, and peroxynitrite in lung tissue also were significantly elevated. Pretreatment with melatonin attenuated obstructive and restrictive ventilatory insufficiency induced by AP. Blood and lavage WBC, lavage LDH and protein, lung edema, oxidative/nitrosative stress, and lipoxygenase pathway derivatives were also significantly attenuated by melatonin. We conclude that melatonin decreases AP-induced obstructive and restrictive lung function changes via its antioxidant and anti-inflammatory properties.

The clinical course of acute pancreatitis and the inflammatory mediators that drive it

Acute pancreatitis (AP) is a common emergency condition. In the majority of cases, it presents in a mild and self-limited form. However, about 20% of patients develop severe disease with local pancreatic complications (including necrosis, abscess, or pseudocysts), systemic organ dysfunction, or both. A modern classification of AP severity has recently been proposed based on the factors that are causally associated with severity of AP. These factors are both local (peripancreatic necrosis) and systemic (organ failure). In AP, inflammation is initiated by intracellular activation of pancreatic proenzymes and/or nuclear factor-κB. Activated leukocytes infiltrate into and around the pancreas and play a central role in determining AP severity. Inflammatory reaction is first local, but may amplify leading to systemic overwhelming production of inflammatory mediators and early organ failure. Concomitantly, anti-inflammatory cytokines and specific cytokine inhibitors are produced. This anti-inflammatory reaction may overcompensate and inhibit the immune response, rendering the host at risk for systemic infection. Currently, there is no specific treatment for AP. However, there are several early supportive treatments and interventions which are beneficial. Also, increasing the understanding of the pathogenesis of systemic inflammation and the development of organ dysfunction may provide us with future treatment modalities.

Thrombin generation in vitro and in vivo, and disturbed tissue factor regulation in patients with acute pancreatitis

BACKGROUND

Being a central link between inflammation and coagulation, tissue factor (TF) and its inhibitor (TFPI) might be associated with the severity of acute pancreatitis (AP) and the development of organ failure (OF).

METHODS

The study comprises 9 severe AP patients with OF and 24 reference patients (11 mild AP and 13 severe AP without OF). Plasma samples were collected on admission. TF-induced thrombin generation in plasma samples was studied using the thrombogram method. In vivo thrombin generation was estimated by prothrombin fragment F1+2. Free and total TFPI levels were measured. To evaluate coagulation status the activated partial thromboplastin time, prothrombin time, platelet count, D-dimer, fibrinogen, antithrombin (AT) 3 and protein C (PC) were determined.

RESULTS

There was no significant difference in F1+2 levels between the patient groups. Patients with severe AP tended to show low platelet counts, PC and AT3 levels, and high D-dimer levels. In 11 patients the standard TF stimulation did not trigger thrombin generation in the thrombogram. All deaths occurred in these patients. Free TFPI levels and free/total TFPI ratios were significantly higher in these patients and in non-survivors.

CONCLUSION

Failure of TF-initiated thrombin generation in the thrombogram assay explained by high levels of circulating free TFPI may be associated with OF and mortality in AP. and IAP.

Patients with acute pancreatitis complicated by organ failure show highly aberrant monocyte signaling profiles assessed by phospho-specific flow cytometry

OBJECTIVES

To outline signaling profiles and transmigration capacity of monocytes of patients with severe acute pancreatitis.

DESIGN

Prospective study.

SETTING

University hospital intensive care unit.

PATIENTS

Thirteen patients with severe acute pancreatitis. All patients had organ dysfunction (acute respiratory distress syndrome in 12, renal dysfunction in eight). Healthy volunteers served as reference subjects.

INTERVENTIONS

Blood samples were collected after admission to the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

Phosphorylation of nuclear factor-kappaB and p38, signal transducers and activators of transcription (STATs) 1, 3, 5, and extracellular signal-regulated kinases 1/2 in appropriately stimulated and nonstimulated samples were studied using phospho-specific whole-blood flow cytometry. Monocyte chemotactic protein-1-induced transmigration of monocytes among mononuclear cells obtained by density gradient centrifugation was studied using Transwell cell culture inserts covered with confluent layer of endothelial EA-HY cells. Phosphorylation levels of nuclear factor-kappaB induced by tumor necrosis factor, bacterial lipopolysaccharide, muramyl dipeptide, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis were significantly lower in patients' monocytes than monocytes of healthy reference subjects, whereas mitogen-activated protein kinase p38 phosphorylation levels were normal. Phosphorylation levels induced by interleukin-6 in STAT1 and STAT3 and by combination of phorbol 12-myristate 13-acetate and calcium ionophore A23187 in extracellular signal-regulated kinases 1/2, members of a mitogen-activated protein kinase family, were depressed in patients' monocytes, whereas phosphorylation levels induced by granulocyte-macrophage colony-stimulating factor in STAT5 was normal. In nonstimulated samples, phosphorylation levels were normal. The transmigration percentage of patients' monocytes was significantly lower than that of reference monocytes.

CONCLUSIONS

In severe acute pancreatitis, monocytes show impaired nuclear factor kappaB and STAT1 activation, which may increase susceptibility to secondary infections. p38 activation is normal and STAT3 activation is depressed, which may contribute to maintenance of systemic inflammation. Extracellular signal-regulated kinases 1/2 activation is impaired, which may depress monocytes' transmigration and may consequently increase risk of infection. Monitoring of monocyte signaling profiles may aid in finding new therapeutic approaches and predictors of outcome of severe acute pancreatitis.

Sodium/hydrogen exchange inhibition with cariporide reduces leukocyte adhesion via P-selectin suppression during inflammation

BACKGROUND AND PURPOSE

The Na(+)/H(+) exchange (NHE) inhibitor cariporide is known to ameliorate ischaemia/reperfusion (I/R) injury by reduction of cytosolic Ca(2+) overload. Leukocyte activation and infiltration also mediates I/R injury but whether cariporide reduces I/R injury by affecting leukocyte activation is unknown. We studied the effect of cariporide on thrombin and I/R induced leukocyte activation and infiltration models and examined P-selectin expression as a potential mechanism for any identified effects.

EXPERIMENTAL APPROACH

An in vivo rat mesenteric microcirculation microscopy model was used with stimulation by thrombin (0.5 micro ml(-1)) superfusion or ischaemia (by haemorrhagic shock for 60 min) and reperfusion (90 min).

KEY RESULTS

Treatment with cariporide (10 mg kg(-1) i.v.) significantly reduced leukocyte rolling, adhesion and extravasation after thrombin exposure. Similarly, cariporide reduced leukocyte rolling (54+/-6.2 to 2.4+/-1.0 cells min(-1), P<0.01), adherence (6.3+/-1.9 to 1.2+/-0.4 cells 100 microm(-1), P<0.01) and extravasation (9.1+/-2.1 to 2.4+/-1.1 cells per 20 x 100 microm perivascular space, P<0.05), following haemorrhagic shock induced systemic ischaemia and reperfusion. The cell adhesion molecule P-selectin showed a profound decrease in endothelial expression following cariporide administration in both thrombin and I/R stimulated groups (35.4+/-3.2 vs 14.2+/-4.1% P-selectin positive cells per tissue section, P<0.01).

CONCLUSIONS AND IMPLICATIONS

The NHE inhibitor cariporide is known to limit reperfusion injury by controlling Ca(2+) overload but these data are novel evidence for a vasculoprotective effect of NHE inhibition at all levels of leukocyte activation, an effect which is likely to be mediated at least in part by a reduction of P-selectin expression.

Genetic immunodeficiency diseases

The approach to the patient with genetic immunodeficiency is multidisciplinary, and requires close interaction between the primary care physician, immunologist, and other specialists. Dermatologists may play a key role in both the diagnosis of immunodeficiency based on recurrent infection or specific cutaneous abnormalities and in the management of cutaneous complications. The availability of bone marrow and stem cell transplantation has been life-saving for many affected children. The underlying genetic basis is now known for most forms of immunodeficiency, which has facilitated confirmation of patient diagnosis and prenatal diagnosis. Gene therapy has already been initiated for severe combined immunodeficiency, and will certainly play a growing role in therapy of this group of disorders in the future.

Early inflammatory response in acute pancreatitis is little affected by body mass index

OBJECTIVE

Obesity is a known risk factor for severe acute pancreatitis (AP), but the mechanism by which it affects the severity of AP is not fully understood. The main objective of this study was to investigate the relationship between obesity and inflammatory markers in AP.

MATERIAL AND METHODS

Thirty patients with AP who developed organ failure (Group I) and 87 patients with AP who survived without organ failure (Group II) were studied. Patients' height and weight were measured at admission for calculation of body mass index (BMI). Blood samples were taken at admission for measurement of plasma interleukin (IL)-1beta, IL-6, IL-10, IL-1 receptor antagonist, procalcitonin, C-reactive protein (CRP) and monocyte human leucocyte antigen (HLA)-DR expression.

RESULTS

Group I patients had higher BMI values (median 26.2 kg/m2) than Group II patients (25.2 kg/m2), p =0.033. Both CRP values and monocyte HLA-DR expression showed a significant correlation with BMI (Spearman's rank correlation r=0.32, p =0.003 and r= -0.33, p = 0.002, respectively). The correlation between BMI and monocyte HLA-DR expression was significant in Group II patients (r = -0.34, p =0.002) but not in Group I patients (r = -0.02, p >0.05). There was no correlation between BMI and IL-1beta, IL-6, IL-10, IL-1 receptor antagonist or procalcitonin.

CONCLUSIONS

BMI did not affect either proinflammatory or anti-inflammatory cytokine levels in early AP. However, in patients with mild AP, BMI correlated positively with CRP levels and inversely with monocyte HLA-DR expression, which might reflect an amplified inflammatory response in these patients. Taken together, acute inflammatory response in AP, which ultimately determines the severity of AP, was little affected by BMI.

Infusion of Hypertonic Saline (7.5%) Does Not Change Neutrophil Oxidative Burst or Expression of Endothelial Adhesion Molecules After Abdominal Hysterectomy

BACKGROUND

Previous studies found hypertonicity to affect neutrophils in intact laboratory animals and in human blood cell cultures. We investigated whether infusion of hypertonic saline in a clinical relevant dose before hysterectomy affected peripheral blood neutrophils and their response to surgery.

METHODS

Fifteen women scheduled for open abdominal hysterectomy were randomized double-blindly to infusion of 4 mL/kg 7.5% NaCl, 4 mL/kg 0.9% NaCl, or 32 mL/kg 0.9% NaCl over 20 minutes. Blood was collected at baseline, after infusion, 1, 4, and 24 hours postoperatively for the determination of leukocyte and differential count, neutrophil membrane expression of endothelial adhesion molecules by flow cytometry, and O2- -generation by superoxide dismutase-inhibitable reduction of cytochrome C.

RESULTS

Surgery induced well-known changes in the number and distribution of white blood cells, reduced the expression of adhesion molecules, and halved the superoxide production unrelated to the tonicity or volume of the infused fluids.

CONCLUSION

Infusion of a clinically relevant dose of hypertonic saline has no detectable effect on the membrane expression of endothelial adhesion molecules or O2- -generation in circulating neutrophils after elective abdominal hysterectomy.

Identification of a phenotypically and functionally distinct population of long-lived neutrophils in a model of reverse endothelial migration

Recent studies have demonstrated that neutrophils are not a homogenous population of cells. Here, we have identified a subset of human neutrophils with a distinct profile of cell-surface receptors [CD54(high), CXC chemokine receptor 1(low) (CXCR1(low))], which represent cells that have migrated through an endothelial monolayer and then re-emerged by reverse transmigration (RT). RT neutrophils, when in contact with endothelium, were rescued from apoptosis, demonstrate functional priming, and were rheologically distinct from neutrophils that had not undergone transendothelial migration. In vivo, 1-2% of peripheral blood neutrophils in patients with systemic inflammation exhibit a RT phenotype. A smaller population existed in healthy donors ( approximately 0.25%). RT neutrophils were distinct from naïve circulatory neutrophils (CD54(low), CXCR1(high)) and naïve cells after activation with formyl-Met-Leu-Phe (CD54(low), CXCR1(low)). It is important that the RT phenotype (CD54(high), CXCR1(low)) is also distinct from tissue-resident neutrophils (CD54(low), CXCR1(low)). Our results demonstrate that neutrophils can migrate in a retrograde direction across endothelial cells and suggest that a population of tissue-experienced neutrophils with a distinct phenotype and function are present in the peripheral circulation in humans in vivo.

Pentoxifylline reduces indirect lung injury of fresh water drowning in canis

BACKGROUND

Previous studies have suggested that pentoxifylline (PTX) exerts multiple beneficial effects on the inflammatory cascade, particularly on the function of neutrophils. We investigated whether continuous infusion of PTX could reduce indirect lung injury (ILI) caused by fresh water drowning and if so, what is the possible molecular mechanism.

METHODS

Twenty 4 male canis were divided randomly into control group, fresh water drowning group (right lung), drowning treated with PTX group and PTX alone group. At different time points after drowning, the changes of hemodynamic parameters and wet/dry weight of indirect lung (left lung) tissues were compared among these 4 groups. Other measures included lung histopathology, PMN infiltration assessed by immune staining, CD11b, ICAM-1 mRNA and TNF-alphamRNA in left lung detected by RT-PCR. NF-kappaB activation in blood neutrophils and lungs were measured with electrophoretic mobility shift assay (EMSA).

RESULTS

Animals treated with PTX showed a significant reduction in lung injury. PTX suppressed drowning-induced ICAM-1 and TNF-alphamRNA elevation and inhibited NF-kappaB activation in blood neutrophils and lungs.

CONCLUSIONS

Continuous infusion of PTX reduces ILI caused by fresh water drowning. PTX decreases expression of ICAM-1 and TNF-alpha, possibly via inhibition of NF-kappaB.

Aberrant TNF secretion by whole blood in healthy subjects with a history of reactive arthritis: time course in adherent and non-adherent cultures

BACKGROUND

The pathogenesis of reactive arthritis (ReA) apparently involves aberrations in innate immune functions such as monocyte tumour necrosis factor (TNF) generation.

OBJECTIVE

To investigate TNF production in healthy subjects with previous yersinia triggered reactive arthritis.

METHODS

The study comprised HLA-B27 positive subjects with previous reactive arthritis (B27+ReA+), and B27+ReA- and B27-ReA- subjects (n = 15 each). Whole blood TNF production was induced by lipopolysaccharide (LPS), which binds to CD14/TLR4 on the monocyte surface, or by a combination of phorbol 12-myristate 13-acetate (PMA) and Ca(2+) ionophore A23187, which activates monocytes independently of cell surface receptors. To further evaluate the possible role of adhesion mediated signalling on TNF production, blood samples were incubated in adherent or non-adherent conditions. TNF levels in culture supernatants were measured using an automated immunoassay analyser. The CD14(-159)C/T genotype was determined by a cycle minisequencing method.

RESULTS

B27+ReA+ supernatants had higher TNF levels than B27+ReA- supernatants in PMA/A23187 wells in two hour (p = 0.004) and four hour cultures (p = 0.001). Rapid initial TNF release took place in adherent but not in non-adherent conditions. This adhesion associated difference was greater in the B27+ReA+ group than in the B27+ReA- or B27-ReA- group in response to PMA/A23187 (p values <0.001), and greater in the B27+ReA+ group than in the B27-ReA- group in response to LPS (p = 0.021). CD14(-159)T was associated allele dose dependently with an increase in the LPS induced TNF secretion allele (p = 0.030).

CONCLUSIONS

SUBJECTS

who have recovered from yersinia arthritis show enhanced TNF production, which may be regulated at the level of monocyte adhesion.

Activation of neutrophils and monocytes by a leukocyte-depleting filter used throughout cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass elicits systemic inflammation. Depletion of circulating leukocytes might alleviate inflammatory response. We studied the effects of a leukocyte-depleting filter on phagocyte activation during cardiopulmonary bypass.

METHODS

Fifty patients undergoing coronary artery bypass grafting were randomly allocated into an arterial line leukocyte filter group (n = 25) with a Pall LeukoGuard 6 leukocyte-depleting filter (LG6; Pall Biomedical, Portsmouth, United Kingdom) and a control group without any filter (n = 25). Blood sampling took place from arterial line at predetermined time points. In the filter group, the sample was taken immediately before the filter; to evaluate activation at the site, an additional sample was taken immediately after the filter. CD11b/CD18 and L-selectin expressions and basal production of hydrogen peroxide were determined with whole-blood flow cytometry, and plasma lactoferrin level was determined with enzyme-linked immunosorbent assay.

RESULTS

Neutrophil CD11b expression was higher in the filter group than in the control group (P < .001). Likewise, monocyte CD11b expression, neutrophil hydrogen peroxide production, and lactoferrin plasma levels were all significantly higher, whereas neutrophil and monocyte counts and neutrophil L-selectin expression were all significantly lower in the filter group (all P < .001). At 5 minutes of CPB, CD11b expression increased across the filter on neutrophils (median difference 197 relative fluorescence units, range 45-431 relative fluorescence units, P < .001) and monocytes (median difference 26 relative fluorescence units, range -68-111 relative fluorescence units, P < .001).

CONCLUSION

The LG6 arterial line leukocyte filter is ineffective in its principal task of diminishing phagocyte activation during cardiopulmonary bypass.

Effects of unfractionated heparin, low molecular weight heparin and r-hirudin on leukocyte adhesion in ischemia/reperfusion

Activation of the coagulation cascade during myocardial ischemia and reperfusion may contribute to the post-ischemic inflammatory response, mostly via generation of thrombin. We assessed the effect of the anticoagulants unfractionated heparin (UFH), low molecular weight heparin (LMWH) and r-hirudin on leukocyte adhesion and emigration after ischemia and reperfusion in rats. The rat cremaster muscle was prepared for intravital microscopy. One hundred and twenty minutes of ischemia were followed by 90 min of reperfusion. Saline (control), UFH, LMWH or r-hirudin were given 15 min prior to reperfusion and infused for the rest of the observation period. Dosages per kilogram of body weight were (bolus, infusion): saline, 3 ml, 3 ml/h; UFH, 400 IU, 100 IU/h; LMWH, 100 IU, 3 ml/h saline; or r-hirudin, 0.3 mg, 0.15 mg/h. In collecting venules, rolling, adherent, and extravasated leukocytes were counted from recordings of the intravital microscopy. All three anticoagulants similarly attenuated post-ischemic endothelial leukocyte adhesion. In contrast, emigration of leukocytes was only attenuated by r-hirudin. The emigration efficiency of adherent leukocytes (control, 1.21) was unchanged after UFH (1.74), and LMWH (1.51) but decreased after r-hirudin treatment (0.12). The different efficacy of the three anticoagulants in affecting emigration of adherent leukocytes suggests a specific role for the direct thrombin inhibitor r-hirudin in attenuating the post-ischemic inflammatory response. This effect may contribute to the benefits of direct thrombin inhibitors seen in clinical studies after treatment for acute coronary syndromes.

Immune effect of hypertonic saline: fact or fiction?

Hypertonicity affects many parts of the immune system. Animal studies and experiments in isolated cell cultures show that hypertonicity reversibly suppresses several neutrophil functions and at the same time up-regulates T-lymphocyte function. Infusion of hypertonic saline with or without colloids may thus, besides providing efficient plasma volume expansion, ameliorate the detrimental consequences on the immune function of trauma, shock, reperfusion, and major surgery. However, the few clinical studies conducted to date, specifically addressing the immune effect of hypertonic saline infusion, have shown little, if any, effect on markers of immune function, and larger clinical trials have not demonstrated benefit in terms of morbidity or mortality. Thus, as opposed to animal and cell-culture studies, the immune-modulating properties of hypertonic saline infusion would appear to be of limited value in clinical practice. This review presents in vitro studies, animal experiments, and clinical trials which investigated the consequences of hypertonic saline on markers of immune function.

Leukocyte and endothelial cell interactions in sepsis: relevance of the protein C pathway

OBJECTIVE

To give an overview of leukocyte and endothelial cell interactions in sepsis and to explore the role of the protein C pathway in modulating the innate immune response via its anti-inflammatory properties.

DATA SOURCE

Novel in vitro data and a MEDLINE search for the terms "activated protein C," "recombinant human activated protein C," "inflammation," "leukocyte adhesion," and "sepsis" were used, along with clinical trial databases from the PROWESS trial and a phase I human endotoxin trial evaluating recombinant human activated protein C (drotrecogin alfa [activated]).

DATA EXTRACTION AND SYNTHESIS

The protein C pathway is positioned at the interface between the endothelium and the leukocyte response of the innate immune system. Activated protein C (APC) possesses profibrinolytic, anti-inflammatory, and anti-apoptotic properties, acting as an endothelial cell and microvascular modulator in opposition to thrombin and the proinflammatory cytokines. Distribution of the receptor for APC, endothelial protein C receptor, was detected on effector cells of the innate immune response. This suggests a further role for the protein C pathway in regulating inflammation. In neutrophils and eosinophils, an endothelial protein C receptor-mediated APC response leads to reduced migration in response to cytokine gradients. Endothelial protein C receptor may also suppress the apoptotic response in monocytes and enhance the expression of the adhesion integrin CD11b in granulocytes. The microvascular, anti-inflammatory influence of APC in sepsis is supported by suppression of endothelial cell adhesion molecules and the ability of APC to protect the endothelium from inflammatory insult.

CONCLUSIONS

The coordinated effects of the protein C pathway on the endothelium and the leukocyte response of the innate immune system are supported by potential restriction of endothelial protein C receptor expression to cells of the innate immune system and by suppression of adhesion molecule expression on the endothelium by APC. Reduced neutrophil migration in response to cytokines is also mediated by endothelial protein C receptor. Further clinical studies will be needed to define the intrinsic role of the protein C pathway in coordinating the innate immune response in endothelium-based inflammation.

Phagocyte immunodeficiencies and their infections

Primary immunodeficiencies (PIDs) primarily affecting the phagocytes (neutrophils and macrophages) typically predispose patients to infections. However, one of the most clinically important features of these disorders is their relatively narrow spectrum of disease-specific infections. Invasive aspergillosis in the absence of immune suppression is essentially seen only in chronic granulomatous disease; disseminated nontuberculous mycobacterial infection in the absence of immune suppression is seen predominantly in patients with defects of the IFN-gamma/IL-12 axis. In contrast, infections that are relatively common in some of the PIDs affecting the lymphoid system (Pneumocystis jiroveci and Streptococcus pneumoniae) are extremely uncommon in PIDs affecting phagocytes. Therefore careful attention to the microbiology laboratory early in the course of evaluation of a patient with recurrent infections and suspected of having a PID will help steer the workup in the appropriate direction. Over the last few years, there have been major advances in the molecular and cellular understandings of PIDs affecting phagocytes. As the field of PIDs becomes broader and more clinical and molecular definition becomes available, it is increasingly important to be able to identify likely pathways for investigation early in the evaluation. Here we have updated some of the more rapidly evolving aspects of PIDs affecting phagocytes, with a special emphasis on the associated microbiology.

Pentoxifylline reduces acute lung injury in chronic endotoxemia

BACKGROUND

Pentoxifylline (PTX) attenuates end-organ injury in models of sepsis and hemorrhage. PTX is thought to act by inhibiting phosphodiesterase, thus increasing cAMP and decreasing tumor necrosis factor-alpha (TNF-alpha) synthesis. The effects of PTX on neutrophil and endothelial cell adhesion molecules and, ultimately, organ injury in a chronic endotoxemia model have not been studied. We hypothesized that continuous infusion of PTX reduces acute lung injury (ALI) caused by chronic lipopolysaccharide (LPS) exposure.

MATERIALS AND METHODS

Male Sprague-Dawley rats were given continuous infusion of LPS, PTX + LPS combined, or saline (sham) by implantable pumps. Neutrophil CD11b expression, lung histopathology, lung intercellular adhesion molecule-1 (ICAM-1) expression assessed by immune staining, serum TNF-alpha, serum interleukin-6 (IL-6), and bronchoalveolar lavage (BAL) IL-8 were evaluated at different time points. Lung injury was graded in a blinded fashion from 0 (normal) to 4 (severe) for interstitial inflammation, neutrophil infiltration, congestion, and edema. Total lung injury score (TLIS) was calculated by adding listed categories. White cell count in the peripheral blood and in the BAL was also performed.

RESULTS

Animals treated with PTX + LPS showed a significant reduction in lung injury score, a marked decrease in ICAM-1 expression, and a significant decrease in IL-8 levels in the BAL and serum IL-6 levels when compared with LPS-treated animals.

CONCLUSIONS

Continuous infusion of PTX reduces ALI caused by chronic endotoxemia. The effect seems to be a result of decreased expression of endothelial and epithelial ICAM-1 and modulation of proinflammatory cytokine synthesis.

Serum levels of mast cell tryptase, vascular endothelial growth factor and basic fibroblast growth factor in patients with acute pancreatitis

PURPOSE

Mast cell tryptase, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) possibly play a role in the pathogenesis of acute pancreatitis (AP). The aim is to describe their serum levels in relation to severity of AP.

METHODS

Seventy patients with AP were studied. Thirty-one had mild acute pancreatitis and 39 severe AP of whom 21 developed organ dysfunction. Serum concentration of tryptase was determined with fluoroimmunoassay (UniCAP), and VEGF and bFGF with ELISA at admission and on days 1, 2, and 7 post-hospitalization.

RESULTS

The peak tryptase levels and tryptase levels at 2nd day after symptom onset, although mostly within normal range, were significantly higher in patients with organ dysfunction than in patients without organ dysfunction (6.6 microg/l (inter quartile range 4.8 to 12.6) versus 4.0 microg/l (2.7 to 6.2); P = 0.018 and 6.0 microg/l (4.4 to 7.6) versus 3.4 microg/l (2.3 to 4.8); P = 0.006, respectively). Median serum VEGF and bFGF concentrations increased during follow-up, were significantly higher on day 7 than on days 0, 1, and 2, but were not related to development of organ dysfunction.

CONCLUSIONS

Mast cell activation, as defined by serum tryptase levels, may play a role in the development of remote organ dysfunction in patients with AP. However, neither tryptase nor the factors VEGF and bFGF serve as predictors of organ dysfunction in clinical AP.

Effects of magnetic cell separation on monocyte adhesion to endothelial cells under flow

Studies on monocyte adhesion are frequently limited by spontaneous changes of CD11b and CD62L during cell purification. Most isolation protocols for flow cytometric analysis that overcome this problem cannot be used when large numbers of living cells are needed for functional adhesion assays. This study investigated whether magnetic cell separation of monocytes with a paramagnetic bead against CD33 is a feasible method combining high yield with a low degree of spontaneous activation. As determined by flow cytometry, isolation of magnetically tagged monocytes at 4 degrees C did not alter the expression of CD11b and CD62L when compared to whole blood controls. Warming the cells slowly to room temperature immediately before starting the adhesion assay in a parallel plate flow chamber at 37 degrees C prevented further upregulation of adhesion molecules due to rewarming. When adhesion of magnetically tagged monocytes was compared with untouched monocytes that had been isolated via depletion of contaminating leukocytes, videomicroscopy showed that labelling CD33 neither affected rolling nor firm adhesion to human umbilical venous endothelial cells under flow. Finally, the subsequent upregulation of tissue factor expression on adherent monocytes indicates that magnetically separated monocytes responded properly to activating stimuli during cell adhesion. We conclude that magnetic cell separation via CD33 represents a feasible method for cell separation whenever large numbers of non-activated monocytes are needed for adhesion assays under flow.

Degranulation of primary and secondary granules in adherent human neutrophils

The aim of this study was to investigate whether neutrophil adhesion to extracellular matrix proteins like fibronectin, fibrinogen, and albumin influence the release proteins from primary and secondary granules of neutrophils stimulated by phorbol-myristate-acetate (PMA) and formyl-methionyl-leucyl-phenylalanine (f-MLP). Isolated granulocytes plated on wells coated with fibronectin, fibrinogen, and albumin were stimulated with f-MLP (10-7 mol/l), PMA (10-9 mol/l), Mn2+ (5 mmol/l), or combinations of these stimuli, and the degree of adhesion to protein-coated surfaces and the amount of granule proteins released was quantified during 90 min of incubation. PMA, in combination with Mn2+, induced a maximum release of approximately 80% of the intracellular content of lactoferrin and human neutrophil lipocalin (HNL) and 15-20% of the myeloperoxidase (MPO) content regardless of the protein used. PMA or f-MLP alone induced 30-40% release of lactoferrin and HNL depending on the protein that the cells were plated on. Adhesion and release of lactoferrin and HNL were quantitatively related when induced by PMA and PMA plus Mn2+, but not by f-MLP. The mean release of lactoferrin and HNL showed a significant negative relationship to the viability of the cells. In conclusion, adhesion modulates neutrophil degranulation, but it is not always quantitatively related or related in time.

Markers of inflammation in sepsis

Pathophysiology of sepsis is characterised by a whole body inflammatory reaction and concurrent activation of the host's anti-inflammatory mechanisms. The balance between pro- and anti-inflammatory reactions is critical for the outcome of the patient. Strongly activated phagocytes and high levels of proinflammatory cytokines occur in patients who are at risk of developing circulatory shock and multiple organ dysfunction. Extensive anti-inflammatory reaction, which is characterised by the presence of high levels of circulating anti-inflammatory cytokines and impaired innate and adaptive immune functions, renders critically ill patients prone to secondary infections. Evaluation of the immune-inflammatory status on admission to the hospital may be helpful in the early identification of patients who are bound to develop organ dysfunction. Such patients could possibly benefit from a mode of therapy aimed at modifying the course of inflammatory response. The use of inflammatory markers may also improve diagnosis of severe infection. The present review summarises the studies on markers of inflammation and immune suppression used, first, as predictors of organ dysfunction in patients with systemic inflammation, and, second, as indicators of infection in adults and neonates.

Cariporide (HOE 642) attenuates leukocyte activation in ischemia and reperfusion

Cariporide (HOE 642) ameliorates myocardial ischemia/reperfusion (I/R) injury, by the well established reduction of cytosolic [Ca(2+)] in cardiac myocytes through inhibition of Na(+)/H(+) exchange. However, postischemic inflammation also contributes to I/R injury. We tested the hypothesis that cariporide also modulates the inflammatory response. The effect of cariporide on L-selectin expression by human leukocytes in vitro and leukocyte adhesion and emigration in the reperfused rat cremaster muscle in vivo were studied. The rat cremaster muscle was exteriorized for intravital videomicroscopy, induction of ischemia (90 min), and reperfusion (90 min). Eleven rats were pretreated with cariporide (9 mg/kg body weight IV) whereas 11 rats received saline. Leukocyte adhesion was quantified offline. Human venous blood was incubated with cariporide (3 micromol/L) or saline, stimulated with formyl- methionine-leucine-phenylalanine (10(-10)-10(-6) mol/L), and granulocyte L-selectin expression was analyzed by flow cytometry. Cariporide reduced leukocyte rolling and adhesion by approximately 35% and 45%, respectively, after 30 min of reperfusion. Leukocyte extravasation was decreased by approximately 85% after 90 min. Cariporide increased L-selectin shedding at each formyl-methionine-leucine-phenylalanine concentration, reducing the 50% effective dose from 9.95 to 4.68 nmol/L. Thus, cariporide may ameliorate I/R injury not only by the known reduction of cytosolic [Ca(2+)] in cardiomyocytes, but also by attenuating leukocyte-dependent inflammatory responses. Promotion of L-selectin shedding from activated leukocytes may present a mechanism underlying this newly detected effect.

IMPLICATIONS

This study provides evidence that inhibition of Na(+)/H(+) exchange by cariporide (HOE 642) attenuates the postischemic inflammatory response. Leukocyte adhesion and emigration, assessed by in vivo microscopy, were markedly reduced in rat cremaster muscle, possibly because of increased L-selectin shedding of activated leukocytes as demonstrated by flow cytometry.

Cellular markers of systemic inflammation and immune suppression in patients with organ failure due to severe acute pancreatitis

BACKGROUND

Few data are available on cellular markers of systemic inflammation and immune suppression in early acute pancreatitis. The aim of this study was to describe the cellular immune inflammatory status of patients with acute pancreatitis in relation to development of organ failure.

METHODS

Prospective study including 89 patients who presented within 72 h of onset of pain. Fifty-eight of them had mild disease (Grade I group), 19 had severe disease with no organ dysfunction (Grade II group) and 12 had severe disease with organ dysfunction (Grade III group). Serial blood samples were collected on admission and following 2 days. Phagocyte surface markers were analysed using flow cytometry.

RESULTS

The proportion of HLA-DR-positive monocytes, a marker of immune suppression, and CD11b expression level on neutrophils and monocytes, a marker of systemic inflammation, were related to Grades I-III (P for trend <0.001). In Grade III patients, the proportion of HLA-DR-positive monocytes was low on presentation, or decreased rapidly during follow-up, whereas CD11b expression levels were persistently high. L-selectin and monocyte CD14 expression levels were not related to disease severity.

CONCLUSIONS

Immune suppression develops early, rapidly and unexpectedly in patients with acute pancreatitis. Monitoring immune inflammatory status may provide the means by which to identify patients who benefit from biological response modifier therapy.

Effect of mechanical deformation of neutrophils on their CD18/ICAM-1-dependent adhesion

Mechanical deformation of polymorphonuclear leukocytes (PMN) changes their expression of the surface adhesion molecule CD11b/CD18. We tested the hypothesis that mechanical deformation of PMN enhances their adhesiveness. Purified human PMN were deformed through either 5- or 3-microm polycarbonate membrane filters and allowed to adhere to 96-well plates coated with human recombinant intercellular adhesion molecule-1 (ICAM-1). Flow cytometric studies showed that deformation of PMN increased CD11b/CD18 expression (P < 0.01). PMN adhesion to ICAM-1-coated plates was dependent on the magnitude of cell deformation (5 microm, 63.8 +/- 8.1%, P < 0.04; 3 microm, 232.4 +/- 20.9%, P < 0.01). Priming of PMN (0.5 nM N-formyl-methionyl-leucyl-phenylalanine) before deformation (5 microm) increased PMN adhesion (63.8 +/- 8.1 vs. 105.3 +/- 16.4%; P < 0.04). Stimulation (5% zymosan-activated plasma) of PMN after deformation resulted in increased adhesion, and the degree of increase was dependent on the magnitude of PMN deformation (stimulation, 50.6 +/- 4%; 5-microm filtration and stimulation, 62.9 +/- 6.6%; 3-microm filtration and stimulation, 249.9 +/- 24.2%; P < 0.01). This study shows that mechanical deformation of PMN causes an increase in PMN adhesiveness to ICAM-1 that was enhanced by both priming of PMN before deformation and stimulation after cell deformation.

Procalcitonin strip test in the early detection of severe acute pancreatitis

BACKGROUND

Early identification of patients who subsequently develop severe acute pancreatitis would enable the selection of patients who may benefit from early intensive management. Because severe acute pancreatitis is characterized by the development of systemic inflammation the authors studied whether procalcitonin, a marker of systemic inflammation, differentiated between patients with mild and severe acute pancreatitis.

METHODS

On admission and 24 h thereafter, serum procalcitonin level was measured by a rapid, semiquantitative PCT-Q test and serum C-reactive protein (CRP) by an immunoturbidimetric method in a consecutive series of 162 patients with acute pancreatitis. There were 38 severe and 124 mild cases. The accuracy of procalcitonin and CRP in predicting severe acute pancreatitis was compared with that of Ranson and Acute Physiology and Chronic Health Evaluation (APACHE) II scores.

RESULTS

The PCT-Q test was more accurate in predicting severe acute pancreatitis (sensitivity 92 per cent and specificity 84 per cent at 24 h) than CRP, APACHE II score and Ranson score. Its negative predictive value was high (97 per cent at 24 h), and it detected each patient who developed subsequent organ failure (n = 22).

CONCLUSION

The PCT-Q test was a useful screening method for detecting severe acute pancreatitis. It is simple and quick to perform and, unlike currently available multiple factor scoring systems, can easily be adopted into routine clinical practice.

Procalcitonin, soluble interleukin-2 receptor, and soluble E-selectin in predicting the severity of acute pancreatitis

OBJECTIVE

To investigate whether marker(s) of systemic inflammation detect, at an early stage of acute pancreatitis, patients who may ultimately develop severe disease.

DESIGN

Prospective study.

SETTING

University hospital emergency unit.

PATIENTS

Thirty patients with mild acute pancreatitis (SEV0 group) and 27 with severe acute pancreatitis. Of the latter, 11 did not develop organ failure (SEV1 group), whereas the other 16 patients developed acute respiratory failure and 9 of them also developed renal failure (SEV2 group).

INTERVENTIONS

Blood samples were collected at admission to the hospital (T0), and at 12 hrs (T12) and 24 hrs (T24 after admission.

MEASUREMENTS AND MAIN RESULTS

The plasma concentrations of procalcitonin (PCT), soluble E-selectin (sE-selectin), soluble interleukin-2 receptor (sIL-2R), and the serum concentration of C-reactive protein (CRP) were monitored. PCT levels at T0 were significantly higher in the SEV1 group (median 0.4 ng/mL, range 0.2-2.3) and the SEV2 group (0.8 ng/mL, 0.2-73.5) than in the SEV0 group (0.3 ng/mL, 0.1-3, p < .05 and p < .001, respectively). At T12, PCT level in the SEV2 group was significantly higher than that in the SEV1 group (2.2 ng/mL, 0.2-86.6 vs. 0.4 ng/mL, 0.3-2.8, p = .05), as it also was at T24 (2.2 ng/mL, 0.4-73.3 vs. 0.5 ng/mL, 0.3-4, p < .01). Among SEV2 patients, PCT concentration correlated negatively with the time elapsed between admission and the diagnosis of organ failure. At T12, sIL-2R levels of the SEV1 group (1,011 U/mL, range 334-2,211) and the SEV2 group (1,495 U/ml, range 514-4,526) both differed significantly from the SEV0 group (636 U/ml, range 356-1,678, p < .05 and p < .001, respectively) as they also did at T24. Although CRP level in the SEV1 group at T12 did not differ from the SEV0 group, the difference between SEV2 (272 microg/mL, range 46-462) and SEV0 was significant (53 microg/mL, range 5-243, p < 0.01). sE-selectin levels did not differ between groups.

CONCLUSIONS

At admission to hospital, concentrations of PCT, but not those of CRP, sE-selectin, or sIL-2R, are higher in patients with severe acute pancreatitis than in patients with mild pancreatitis. PCT test had sensitivity of 94% and specificity of 73% for development of organ failure. PCT may be useful to identify the patients who benefit from novel therapies aimed at modifying the course of systemic inflammation.

Synthesis and glycan priming activity of acetylated disaccharides

Five disaccharides related in structure to the glycans of vertebrate mucins have been chemically synthesized using orthogonal blocking, coupling and deblocking techniques. These include 2-naphthylmethyl 3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl-( 1 --> 4)-2-acetamido-3,6-di-O-acetyl-2-deoxy-beta-D-glucopyranoside (6), 2-naphthylmethyl 2-aceta-mido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl-(1 --> 3)-2,4,6-tri-O-acetyl-beta-D-galactopyranoside (14), 2-naph-thylmethyl2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl-(1 --> 3)-2-acetamido-4,6-di- O-acetyl-2-deoxy-alpha-D-galactopyranoside (20), 2-naphthylmethyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl-(1 --> 3)-2-acetamido-4,6-di-O-acetyl-2-deoxy-alpha-D-galactopyranoside (23) and 2-naphthylmethyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glu-copyranosyl-(1 --> 6)-2-acetamido-3,4-di-O-acetyl-2-deoxy-alpha-D-galactopyranoside (27). These per-O-acetylated compounds were fed to U-937 cells to test their ability to prime oligosaccharide synthesis, inhibit glycoprotein biosynthesis and alter adhesion to E-selectin expressed on endothelial cells. The results show that 6, 14, and 20 served as substrates for oligosaccharide synthesis. The generation of glycoside-primed glycans altered the formation of glycoproteins on the cell surface and inhibited cell adhesion dependent on E-selectin.

Pathophysiologic basis of sepsis: considerations for future strategies of intervention

OBJECTIVE

To analyze the implications for therapeutic advances in the treatment of sepsis and septic shock based on the mechanisms underlying the response to microbial infection.

DATA SOURCES

Clinical trials and experimental models designed to determine the key mechanisms involved in cellular and molecular processes of inflammatory reactions.

STUDY SELECTION

Analyses of normal immune reactions to microbial infection, processes involved in the development of sepsis, and reasons for frequent failure of regimens based on current therapeutic rationales.

DATA EXTRACTION/SYNTHESIS

Review of the data suggests that the dysregulation of the immune system resulting in sepsis/septic shock is ineffectually blocked by interfering with the action of inflammatory mediators or cascades, as these processes may be too complex to be easily antagonized. Rather, blockade of the action of microbial products or of the intracellular processes activated by receptor interaction with these products may provide a more promising therapeutic alternative.

CONCLUSIONS

The sepsis syndrome induced by microbial pathogens reflects excessive stimulation of the processes of innate immunity. Bacterial components reacting with specific receptors activate intracellular processes, resulting in the release of excessive amounts of mediators of inflammation as well as triggering multiple complex proteolytic cascades. Blockade or antagonism of the actions of individual intermediary messenger molecules has proved therapeutically unsuccessful, because blockade of mediators alone does not block the direct activation of processes such as coagulation and complement. The dysregulation that characterizes sepsis may be amenable to blockade of the bacterial components or to the intracellular pathways triggered by these products.