Interleukin-8 in serum and cerebrospinal fluid from patients with meningococcal disease

Comparison of the inflammatory response of brain microvascular and peripheral endothelial cells following infection with Neisseria meningitidis

The interaction of Neisseria meningitidis with both peripheral and brain endothelial cells is a critical event in the development of invasive meningococcal disease. In this study, we used in vitro models based on human brain microvascular endothelial cells (HBMEC), and peripheral endothelial EA.hy926 cells, to investigate their roles in the inflammatory response towards meningococcal infection. Both cell lines were infected with two pathogenic N. meningitidis isolates and secretion of the cytokine interleukin-6 (IL-6), the CXC chemokine IL-8 and the monocyte chemoattractant protein-1 (MCP-1) were estimated by ELISA. Neisseria meningitidis was able to stimulate the production of IL-6 and IL-8 by HBMEC and EA.hy926 cells in a time- and concentration-dependent manner. Interestingly, HBMEC released significant higher amounts of IL-6 and IL-8. Moreover, we observed that heat-killed bacteria stimulated high levels of IL-8. In addition, capsule expression had an inhibitory effect on IL-8 release. We extended our study and included serogroup C strains belonging to sequence type 11 clonal complex (cc) from a recent outbreak in France, as well as isolates belonging to the hypervirulent clonal complexes cc8, cc18, cc32 and cc269 and analyzed their ability to induce the secretion of IL-8 from both cell lines. Although individual variations were observed among different isolates, no clear correlations were observed between strain origin, clinical presentation and IL-8 levels.

Combined inhibition of C5 and CD14 efficiently attenuated the inflammatory response in a porcine model of meningococcal sepsis

Background

Fulminant meningococcal sepsis, characterized by overwhelming innate immune activation, mostly affects young people and causes high mortality. This study aimed to investigate the effect of targeting two key molecules of innate immunity, complement component C5, and co-receptor CD14 in the Toll-like receptor system, on the inflammatory response in meningococcal sepsis.

Methods

Meningococcal sepsis was simulated by continuous intravenous infusion of an escalating dose of heat-inactivated Neisseria meningitidis administered over 3 h. The piglets were randomized, blinded to the investigators, to a positive control group (n = 12) receiving saline and to an interventional group (n = 12) receiving a recombinant anti-CD14 monoclonal antibody together with the C5 inhibitor coversin.

Results

A substantial increase in plasma complement activation in the untreated group was completely abolished in the treatment group (p = 0.006). The following inflammatory mediators were substantially reduced in plasma in the treatment group: Interferon-γ by 75% (p = 0.0001), tumor necrosis factor by 50% (p = 0.01), Interleukin (IL)-8 by 50% (p = 0.03), IL-10 by 40% (p = 0.04), IL-12p40 by 50% (p = 0.03), and granulocyte CD11b (CR3) expression by 20% (p = 0.01).

Conclusion

Inhibition of C5 and CD14 may be beneficial in attenuating the detrimental effects of complement activation and modulating the cytokine storm in patients with fulminant meningococcal sepsis.

Invited review: Neisseria meningitidis lipopolysaccharides in human pathology

Neisseria meningitidis causes meningitis, fulminant septicemia or mild meningococcemia attacking mainly children and young adults. Lipopolysaccharides (LPS) consist of a symmetrical hexa-acyl lipid A and a short oligosaccharide chain and are classified in 11 immunotypes. Lipid A is the primary toxic component of N. meningitidis . LPS levels in plasma and cerebrospinal fluid as determined by Limulus amebocyte lysate (LAL) assay are quantitatively closely associated with inflammatory mediators, clinical symptoms, and outcome. Patients with persistent septic shock, multiple organ failure, and severe coagulopathy reveal extraordinarily high levels of LPS in plasma. The cytokine production is compartmentalized to either the circulation or to the subarachnoid space. Mortality related to shock increases from 0% to > 80% with a 10-fold increase of plasma LPS from 10 to 100 endotoxin units/ml. Hemorrhagic skin lesions and thrombosis are caused by up-regulation of tissue factor which induces coagulation, and by inhibition of fibrinolysis by plasminogen activator inhibitor 1 (PAI-1). Effective antibiotic treatment results in a rapid decline of plasma LPS (half-life 1—3 h) and cytokines, and reduced generation of thrombin, and PAI-1. Early antibiotic treatment is mandatory. Three intervention trials to block lipid A have not significantly reduced the mortality of meningococcal septicemia.

Early detection of neonatal group B streptococcus sepsis and the possible diagnostic utility of IL-6, IL-8, and CD11b in a human umbilical cord blood in vitro model

Background

Group B streptococcus (GBS) infection remains a major cause of neonatal morbidity and mortality, and GBS III is the predominant strain in early-onset GBS neonatal sepsis. To avoid both over- and undertreatment of infants with nonspecific signs of infection, early diagnostic tools are warranted. The aim of this study was to identify biomarkers with high sensitivity and specificity in an early stage of GBS infection. A secondary aim was to assess the utility of a human umbilical cord blood (HUCB) model system of early-onset neonatal sepsis.

Methods

Umbilical cord blood samples from 20 healthy term pregnancies were stimulated for 2 hours with a GBS III isolate from a patient and a commercially available GBS Ia strain. Nonstimulated samples served as controls. Leukocyte surface markers (CD11b, CD64, toll-like receptor [TLR] 2, TLR4, and TLR6) were analyzed by flow cytometry and soluble biomarkers by enzyme-linked immunosorbent assay (interleukin [IL]-6 and -8; interferon-γ-inducing protein [IP]-10; and S100b). The area under the receiver operating characteristic curve (AUC) was calculated for the markers.

Results

GBS III gave the highest responses and AUC values for all biomarkers. Only IL-6 and IL-8 displayed an AUC approaching 0.8 for both GBS serotypes (P<0.001). IL-8 >5,292 pg/mL had both a sensitivity and a specificity of 1.00. IL-6 >197 pg/mL had both a sensitivity and a specificity of 0.95 for GBS III stimulation. CD11b on granulocytes and monocytes was the leukocyte surface marker with the highest AUC values for both GBS serotypes.

Conclusion

In agreement with previous studies, IL-6, IL-8, and potentially CD11b could be useful in diagnosing neonatal GBS infection in an early stage. Our HUCB early-onset neonatal sepsis model may be useful for evaluating biomarkers of neonatal sepsis. The HUCB of neonates with risk factors for sepsis might even be used for diagnostic purposes, but requires further study.

The amino acid sequence of Neisseria lactamica PorB surface-exposed loops influences Toll-like receptor 2-dependent cell activation

Toll-like receptors (TLRs) play a major role in host mucosal and systemic defense mechanisms by recognizing a diverse array of conserved pathogen-associated molecular patterns (PAMPs). TLR2, with TLR1 and TLR6, recognizes structurally diverse bacterial products such as lipidated factors (lipoproteins and peptidoglycans) and nonlipidated proteins, i.e., bacterial porins. PorB is a pan-neisserial porin expressed regardless of organisms' pathogenicity. However, commensal Neisseria lactamica organisms and purified N. lactamica PorB (published elsewhere as Nlac PorB) induce TLR2-dependent proinflammatory responses of lower magnitude than N. meningitidis organisms and N. meningitidis PorB (published elsewhere as Nme PorB). Both PorB types bind to TLR2 in vitro but with different apparent specificities. The structural and molecular details of PorB-TLR2 interaction are only beginning to be unraveled and may be due to electrostatic attraction. PorB molecules have significant strain-specific sequence variability within surface-exposed regions (loops) putatively involved in TLR2 interaction. By constructing chimeric recombinant PorB loop mutants in which surface-exposed loop residues have been switched between N. lactamica PorB and N. meningitidis PorB, we identified residues in loop 5 and loop 7 that influence TLR2-dependent cell activation using HEK cells and BEAS-2B cells. These loops are not uniquely responsible for PorB interaction with TLR2, but NF-κB and MAP kinases signaling downstream of TLR2 recognition are likely influenced by a hypothetical "TLR2-binding signature" within the sequence of PorB surface-exposed loops. Consistent with the effect of purified PorB in vitro, a chimeric N. meningitidis strain expressing N. lactamica PorB induces lower levels of interleukin 8 (IL-8) secretion than wild-type N. meningitidis, suggesting a role for PorB in induction of host cell activation by whole bacteria.

Coadministration of the cyanobacterial lipopolysaccharide antagonist CyP with antibiotic inhibits cytokine production by an in vitro meningitis model infected with Neisseria meningitidis

OBJECTIVES

In this study, the objective was to determine the anti-inflammatory properties of CyP, a cyanobacterial lipopolysaccharide (LPS) antagonist, used in combination with antibiotic chemotherapy during infection of an in vitro meningitis model infected with Neisseria meningitidis (meningococcus).

METHODS

Monocultures of human meningioma cells and meningioma-primary human macrophage co-cultures were infected with meningococci (10(2)-10(8) cfu/monolayer) or treated with isolated outer membranes or purified LPS (0.1-100 ng/monolayer) from N. meningitidis. CyP (1-20 μg/monolayer) was added at intervals from t = 0 to 4 h, with and without benzylpenicillin (1-20 μg/monolayer). The antagonistic effect of CyP and its adjunctive properties to benzylpenicillin administration was determined by measuring cytokine levels in culture supernatants after 24 h.

RESULTS

CyP significantly inhibited (P < 0.05) the secretion of interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1 and RANTES ('regulated upon activation, normal T cell expressed and secreted') (overall reduction levels from 50% to >95%) by meningioma cell lines and meningioma-macrophage co-cultures challenged with either live meningococci or bacterial components. Inhibition was effective when CyP was added within 2 h of challenge (P < 0.05) and was still pronounced by 4 h. In the co-culture model, CyP alone partially inhibited IL-1β secretion, but did not prevent tumour necrosis factor (TNF)-α secretion, whereas penicillin alone inhibited IL-1β and TNF-α but conversely did not reduce MCP-1 and RANTES secretion. However, coadministration of CyP and penicillin in both models had an additive effect and restored the overall inhibitory profile.

CONCLUSIONS

CyP inhibits cytokine production in an in vitro meningitis model and augments the anti-inflammatory response when combined with benzylpenicillin. Administration of an LPS antagonist with antibiotic merits consideration in the emergency treatment of patients presenting with meningococcal infection.

A new dynamic porcine model of meningococcal shock

The objective of this study was to establish a porcine analog of human meningococcal sepsis for pathophysiological investigations and possible future therapy in severe sepsis. Heat-killed Neisseria meningitidis was continuously infused in sublethal concentrations into 10 anesthetized 30-kg pigs (sepsis group). The dose was doubled every 30 min. Six pigs received saline only (control group). The changes described in the succeeding paragraphs were observed in the sepsis group but not in the control group. MAP was aimed to be kept normal by fluid infusion but declined after 3 h in parallel with a decrease in systemic vascular resistance. Pulmonary arterial pressure increased considerably after 30 to 45 min. A massive plasma extravasation was shown by increased hematocrit and a 50% reduction in plasma albumin content. Fluid accumulated in lungs, muscles, and jejunum, as shown by increased wet-dry ratios. Peak inspiratory pressures and fraction of inspired oxygen had to be increased. The cytokines TNF-alpha, IL-1beta, IL-6, IL-8, IL-10, and IL-12 increased markedly. Neutrophils fell to zero-levels, and platelets were markedly reduced. Thrombin-antithrombin complexes increased notably after 120 min. This is the first large animal model of sepsis using whole Neisseria meningitidis. The model simulates well central aspects of human meningococcal sepsis and could be used for future interventional studies.

CC and CXC chemokine levels in children with meningococcal sepsis accurately predict mortality and disease severity

Introduction

Chemokines are a superfamily of small peptides involved in leukocyte chemotaxis and in the induction of cytokines in a wide range of infectious diseases. Little is known about their role in meningococcal sepsis in children and their relationship with disease severity and outcome.

Methods

Monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP) 1α, growth-related gene product (GRO)-α and interleukin (IL)-8 were measured in 58 children with meningococcal sepsis or septic shock on admission and 24 hours thereafter. Nine patients died. Serum chemokine levels of survivors and nonsurvivors were compared, and the chemokine levels were correlated with prognostic disease severity scores and various laboratory parameters.

Results

Extremely high levels of all chemokines were measured in the children's acute-phase sera. These levels were significantly higher in nonsurvivors compared with survivors and in patients with septic shock compared with patients with sepsis (P < 0.0001). The cutoff values of 65,407 pg/ml, 85,427 pg/ml and 460 pg/ml for monocyte chemoattractant protein, for IL-8 and for macrophage inflammatory protein 1α, respectively, all had 100% sensitivity and 94–98% specificity for nonsurvival. Chemokine levels correlated better with disease outcome and severity than tumor necrosis factor (TNF)-α and correlated similarly to interleukin (IL)-6. In available samples 24 hours after admission, a dramatic decrease of chemokine levels was seen.

Conclusion

Initial-phase serum levels of chemokines in patients with meningococcal sepsis can predict mortality and can correlate strongly with disease severity. Chemokines may play a key role in the pathophysiology of meningococcal disease and are potentially new targets for therapeutic approaches.

Cytokine activation in purulent pericarditis caused by Neisseria meningitidis serogroup C

Herein, we report a case of purulent pericarditis caused by Neisseria meningitidis serogroup C in a previously healthy 5-year-old boy, which was detected in pericardial fluid by polymerase chain reaction. The concentrations of interleukin-6, interferon-gamma and interleukin-10 in pericardial fluid were notably increased compared with serum. The role of polymerase chain reaction, counterimmunoelectrophoresis and latex agglutination test in the diagnosis, as well as the participation of cytokines in the pathogenesis of meningococcal pericarditis, are discussed.

Comparative analysis of cytokine gene expression in cerebrospinal fluid of horses without neurologic signs or with selected neurologic disorders

OBJECTIVE

To determine gene transcription for cytokines in nucleated cells in CSF of horses without neurologic signs or with cervical stenotic myelopathy (CSM), West Nile virus (WNV) encephalitis, equine protozoal myeloencephalitis (EPM), or spinal cord trauma.

ANIMALS

41 horses (no neurologic signs [n = 12], CSM [8], WNV encephalitis [9], EPM [6], and spinal cord trauma [6]).

PROCEDURES

Total RNA was extracted from nucleated cells and converted into cDNA. Gene expression was measured by use of real-time PCR assay and final quantitation via the comparative threshold cycle method.

RESULTS

Cytokine genes expressed by nucleated cells of horses without neurologic signs comprised a balance between proinflammatory tumor necrosis factor-alpha (TNF-alpha), anti-inflammatory cytokines (interleukin [IL]-10 and transforming growth factor [TGF]-beta), and Th1 mediators (interferon [IFN]-gamma). Cells of horses with CSM mainly expressed genes for TNF-alpha, TGF-beta, and IL-10. Cells of horses with WNV encephalitis mainly expressed genes for IL-6 and TGF-beta. Cells of horses with EPM mainly had expression of genes for IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma, and TGF-beta. Cells from horses with spinal cord trauma had expression mainly for IL-6; IFN-gamma; TGF-beta; and less frequently, IL-2, IL-10, and TNF-alpha. Interleukin-8 gene expression was only detected in CSF of horses with infectious diseases.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite the small number of CSF samples for each group, results suggest distinct gene signatures expressed by nucleated cells in the CSF of horses without neurologic signs versus horses with inflammatory or traumatic neurologic disorders.

Cytokine responses to fungal pathogens in Kupffer Cells are Toll-like receptor 4 independent and mediated by tyrosine kinases

Disseminated fungal infections are increasing. However, the interactions between the body's largest population of tissue macrophages, the Kupffer cells and the fungal pathogens are scarcely understood. The aim of this study was to examine the involvement of Toll-like receptor 4 (TLR4) signalling in cytokine production, using primary cultures of rat and murine Kupffer cells exposed to Aspergillus fumigatus and Candida albicans hyphae and conidia. All fungal components induced the release of tumour necrosis factor-alpha (TNF-alpha), but with delayed kinetics compared with lipopolysaccharide (LPS). Candida albicans was the most potent inducer of TNF-alpha protein and mRNA and the only inducer of interleukin-10 (IL-10) in rat Kupffer cells. All fungal components induced enhanced mRNA levels of macrophage inhibitory protein-2 (MIP-2) in the cells, similar to LPS. Inhibitors of Src tyrosine kinases added to cells prior to stimulation led to attenuation in the release of both TNF-alpha (60%, P < 0.05) and IL-10 (70%, P < 0.05) induced by C. albicans conidia but did not influence the LPS-mediated cytokine release. Murine Kupffer cells (C57BL/10J) also released TNF-alpha as well as the chemokines keratinocyte-derived chemokine (KC) and MIP-2 in response to fungal component. Surprisingly, Kupffer cells from TLR4-deficient C57BL/ScCr mice exhibited significantly enhanced production of KC and MIP-2 upon stimulation by fungal components compared with control littermates (P < 0.05). Our study demonstrates that Aspergillus and Candida components induce cytokine production in rat Kupffer cells and that the response to C. albicans conidia involves Src tyrosine kinases. The experiments with TLR4-deficient Kupffer cells suggest that the cytokine response in these cells to fungal component is not mediated by TLR4.

Activation of human meningeal cells is modulated by lipopolysaccharide (LPS) and non-LPS components of Neisseria meningitidis and is independent of Toll-like receptor (TLR)4 and TLR2 signalling

The interactions of Neisseria meningitidis with cells of the meninges are critical to progression of the acute, compartmentalized intracranial inflammatory response that is characteristic of meningococcal meningitis. An important virulence mechanism of the bacteria is the ability to shed outer membrane (OM) blebs containing lipopolysaccharide (LPS), which has been assumed to be the major pro-inflammatory molecule produced during meningitis. Comparison of cytokine induction by human meningeal cells following infection with wild-type meningococci, LPS-deficient meningococci or after treatment with OM isolated from both organisms, demonstrated the involvement of non-LPS bacterial components in cell activation. Significantly, recognition of LPS-replete OM did not depend on host cell expression of Toll-like receptor (TLR)4, the accessory protein MD-2 or CD14, or the recruitment of LPS-accessory surface proteins heat shock protein (HSP)70, HSP90alpha, chemokine receptor CXCR4 and growth differentiation factor (GDF)5. In addition, recognition of LPS-deficient OM was not associated with the expression of TLR2 or any of these other molecules. These data suggest that during meningococcal meningitis innate recognition of both LPS and non-LPS modulins is dependent on the expression of as yet uncharacterized pattern recognition receptors on cells of the meninges. Moreover, the biological consequences of cellular activation by non-LPS modulins suggest that clinical intervention strategies based solely on abrogating the effects of LPS are likely to be only partially effective.

A predominantly anti-inflammatory cytokine profile is associated with disease severity in meningococcal sepsis

OBJECTIVE

This study aimed to determine whether an anti-inflammatory profile in meningococcal disease is associated with an increased risk of severe disease or septic shock.

DESIGN AND SETTING

Prospective observational study in a tertiary care children's hospital.

PATIENTS AND PARTICIPANTS

63 children with confirmed meningococcal disease.

INTERVENTIONS

Plasma concentrations of interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF) were assayed on admission. Receiver operator characteristic curve analysis was used to determine optimum thresholds for IL-1Ra:TNF, IL-1Ra:IL-6 and IL-1Ra:IL-8 ratios.

MEASUREMENTS AND RESULTS

Median IL-1Ra:TNF and IL-1Ra:IL-6 ratios were significantly higher in severe disease with septic shock than in severe disease without septic shock and in non severe disease (IL-1Ra:TNF 263 vs. 185 vs. 108; IL-1Ra:IL-6 139 vs. 23 vs. 17). Median IL-1Ra:IL-8 ratios were not significantly different in the three groups. A significantly larger proportion of children with high IL-1Ra:TNF-alpha and IL-1Ra:IL-6 ratios developed severe disease with septic shock than those with a low ratios (95.2% vs. 4.8%; 76.2% vs. 23.8%).

CONCLUSIONS

An anti-inflammatory profile appears to be associated with the development of severe disease and septic shock in meningococcal sepsis. This may imply that experimental new therapies of pro-inflammatory cytokine inhibition and anti-inflammatory cytokines in meningococcal disease could be detrimental.

Cytokines involved in CNS manifestations caused by Mycoplasma pneumoniae

Mycoplasma pneumoniae sometimes causes central nervous system manifestations, which may involve the host immune response, as the organism does not directly damage neural cells, or release toxins. Therefore we measured the levels of interleukin-6, interleukin-8, interleukin-18, interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta1 in serum and cerebrospinal fluid samples from patients who manifested central nervous system manifestations during acute M. pneumoniae infection. The subjects were nine patients with early-onset encephalitis (central nervous system disease onset within 7 days from the onset of fever), four with late-onset encephalitis (onset at 8 days or later), three with encephalitis but without fever, and three with aseptic meningitis. Intrathecal elevations of interleukin-6 and interleukin-8 in all four types of central nervous system manifestations, and of interleukin-18 in late-onset encephalitis were observed. None of the cerebrospinal fluid samples contained detectable levels of interferon-gamma, tumor necrosis factor-alpha, or transforming growth factor-beta1. In conclusion, interleukin-6, interleukin-8, and interleukin-18 might be involved in the inflammatory process leading to the central nervous system manifestations caused by M. pneumoniae.

Serum interleukin-8 in children with biliary atresia: relationship with disease stage and biochemical parameters

Biliary atresia (BA) is a neonatal obliterative cholangiopathy of unknown etiology. Despite the Kasai procedure, hepatic fibrosis and portal hypertension (PH) still occur. Interleukin-8 (IL-8) is an important mediator of inflammation and immune response in human disease. The objective of this study was to investigate the potential role of IL-8 in the pathogenesis of the progressive, sclerosing, inflammatory process and fibrosis in BA. A total of 60 pediatric patients with BA and 15 healthy children were evaluated. The mean ages of BA patients and controls were 6.3 +/- 0.6 and 6.7 +/- 1.1 years, respectively. The patients were classified into two groups according to their clinical outcomes: patients with jaundice (total bilirubin +/- 25.5 micromol/l) and patients without jaundice (total bilirubin < 25.5 micromol/l). The IL-8 levels in serum samples were determined by commercially available enzyme-linked immunosorbent assay. Serum IL-8 levels were higher in the BA patients than in healthy children (236.2 +/- 60.1 vs. 34.5 +/- 12.1 pg/ml, P < 0.001). Patients with jaundice had lower levels of albumin but had greater levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase compared with patients without jaundice. Serum IL-8 levels in the jaundice group were significantly higher than in those without jaundice (516.5 +/- 130.0 vs. 49.3 +/- 10.4 pg/ml, P < 0.0005). Furthermore, patients with PH had higher IL-8 levels than those without PH (378.1 +/- 102.2 vs. 106.6 +/- 48.4 pg/ml, P < 0.005). In the jaundice-free group, IL-8 levels were elevated in patients with PH compared with those without PH (79.0 +/- 17.4 vs. 19.7 +/- 5.8 pg/ml, P < 0.005). The present study demonstrated elevation of serum IL-8 levels in children with BA. Serum IL-8 levels were also higher in patients with jaundice compared with patients without jaundice. These findings suggest that IL-8 may play a significant role in the pathogenesis of BA.

Outer membrane vesicles (OMVs) and detoxified lipooligosaccharide (dLOS) obtained from Brazilian prevalent N. meningitidis serogroup B strains protect mice against homologous and heterologous meningococcal infection and septic shock

Neisseria meningitidis (N. meningitidis) is a serious bacterial pathogen that causes life-threatening invasive bacterial infections especially in children below 2 years of age, teenagers and young adults. We have investigated the protective potential of outer membrane vesicles (OMVs) and detoxified lipooligosaccharide (dLOS) obtained from Brazilian prevalent N. meningitidis serogroup B strains. Swiss mice were immunized with different combinations of OMV and dLOS from N. meningitidis serogroup B strains compared to a reference vaccine (VA-MENGOC-BC), Cuba). The OMVs + dLOS from Brazilian prevalent strains induced higher bactericidal antibody titers against homologous and heterologous target strains and stronger inhibition of thrombocytopenia as compared to the reference vaccine. When the challenge was performed with the B strain, all immunogens tested showed similar survival rates (80%) significantly higher than the control group. Bacterial clearance against the group B strain was comparable for animals immunized with the tested immunogen and the reference vaccine. Inclusion of dLOS from the B strain with the OMV, induced a similar clearance of C strain bacteria as compared to VA-MENGOC-BC. The immunogens, as well as the reference vaccine drastically inhibited increases in TNF-alpha and IL-6 plasma levels after challenge. In conclusion, the OMV/dLOS formulation obtained from Brazilian prevalent strains of N. meningitidis has a remarkable performance protecting mice against the lethal effects of meningococcal challenge showing a good potential as a vaccine and should be considered for clinical evaluation.

Complement activation and complement-dependent inflammation by Neisseria meningitidis are independent of lipopolysaccharide

Fulminant meningococcal sepsis has been termed the prototypical lipopolysaccharide (LPS)-mediated gram-negative septic shock. Systemic inflammation by activated complement and cytokines is important in the pathogenesis of this disease. We investigated the involvement of meningococcal LPS in complement activation, complement-dependent inflammatory effects, and cytokine or chemokine production. Whole blood anticoagulated with lepirudin was stimulated with wild-type Neisseria meningitidis H44/76 (LPS+), LPS-deficient N. meningitidis H44/76lpxA (LPS-), or purified meningococcal LPS (NmLPS) at concentrations that were relevant to meningococcal sepsis. Complement activation products, chemokines, and cytokines were measured by enzyme-linked immunosorbent assays, and granulocyte CR3 (CD11b/CD18) upregulation and oxidative burst were measured by flow cytometry. The LPS+ and LPS- N. meningitidis strains both activated complement effectively and to comparable extents. Purified NmLPS, used at a concentration matched to the amount present in whole bacteria, did not induce any complement activation. Both CR3 upregulation and oxidative burst were also induced, independent of LPS. Interleukin-1beta (IL-1beta), tumor necrosis factor alpha, and macrophage inflammatory protein 1alpha production was predominantly dependent on LPS, in contrast to IL-8 production, which was also markedly induced by the LPS- meningococci. In this whole blood model of meningococcal sepsis, complement activation and the immediate complement-dependent inflammatory effects of CR3 upregulation and oxidative burst occurred independent of LPS.

Plasma interferon-gamma and interleukin-10 concentrations in systemic meningococcal disease compared with severe systemic Gram-positive septic shock

OBJECTIVE

To analyze plasma interferon-gamma and interleukin-10 concentrations in patients with systemic meningococcal disease and patients with severe Gram-positive septic shock caused by Streptococcus pneumoniae or Staphylococcus aureus. To study the in vitro cytokine (interferon-gamma and interleukin-10) responses in a whole blood model boosted with heat-killed Neisseria meningitidis, S. pneumoniae, and S. aureus before and after treatment with recombinant interleukin-10 or recombinant interferon-gamma.

DESIGN

Experimental study.

SETTING

Laboratory.

SUBJECTS

Plasma samples were collected from patients with systemic meningococcal disease (n = 66) and patients with severe Gram-positive septic shock caused by S. pneumoniae (n = 4) or S. aureus (n = 3).

INTERVENTIONS

Whole blood was boosted with heat-killed N. meningitidis, S. pneumoniae, and S. aureus (1 x 106 colony forming units/mL), and plasmas were analyzed for interleukin-10 or interferon-gamma at 0, 5, 12, and 24 hrs. Furthermore, recombinant interleukin-10 or recombinant interferon-gamma was added before bacteria, and the effect on the secretion of interferon-gamma and interleukin-10, respectively, was analyzed after 24 hrs.

MEASUREMENTS AND MAIN RESULTS

The median concentration of interferon-gamma was 15 pg/mL and of interleukin-10 was 10,269 pg/mL in patients with meningococcal septic shock (n = 24) compared with median interferon-gamma concentration of 3400 pg/mL and interleukin-10 concentration of 465 pg/mL in patients with severe Gram-positive shock (p =.001). Increased interferon-gamma concentrations were associated with case fatality (p =.011). In a whole blood model we demonstrated that 1 x 106 colony forming units/mL of N. meningitidis induced more interleukin-10 but less interferon-gamma than S. pneumoniae. S. aureus induced minimal secretion of both cytokines. Recombinant interleukin-10 efficiently down-regulated the secretion of interferon-gamma, and vice versa, as shown in a whole blood model.

CONCLUSION

We speculate whether high concentrations of interleukin-10 contribute to the low concentrations of interferon-gamma in fulminant meningococcal septicemia. In addition, it appears as if interferon-gamma plays a minor role in the pathophysiology of meningococcal septic shock.

Chemotactic activity of CXCL5 in cerebrospinal fluid of children with bacterial meningitis

CXCL5 (epithelial-cell-derived neutrophil-activating protein (ENA-)78) is a CXC-chemokine that specifically acts on neutrophils. To obtain insight into the extent of local presence and action of CXCL5 during bacterial meningitis, we measured its concentrations in cerebrospinal fluid (CSF) of patients with culture-proven bacterial meningitis (n=14), aseptic meningitis (n=6), and controls (n=32) and compared these results with levels of other CXC-chemokines, CXCL8- (interleukin-8) and CXCL1-related oncogene (growth-related oncogene (GRO)-alpha). Patients with bacterial meningitis had profoundly elevated CSF concentrations of all three chemokines. CXCL5 was not detectable in patients with aseptic meningitis or control subjects. CSF from patients with bacterial meningitis exerted chemotactic activity towards neutrophils, which was partially inhibited by neutralizing antibodies against CXCL5 and CXCL8, but not CXCL1. CSF from controls exerted minor chemotactic activity, which could be strongly enhanced by the addition of recombinant CXCL5, CXCL8 or CXCL1. During bacterial meningitis, CXCL5 is elevated in CSF, where it is involved in the recruitment of neutrophils to the central nervous system.

New and old diagnostic markers of meningitis in cerebrospinal fluid (CSF)

Five new markers (tumor necrosis factor TNF-alpha, interleukin IL-1 beta, IL-6, IL-8, lipopolysaccharide binding protein (LBP)) and 11 old classical markers were evaluated in 180 cerebrospinal fluid (CSF) and serum pairs to discriminate acute bacterial meningitis (BM) on admission from aseptic (viral) meningitis (AM), bacterial meningitis treated with antibiotics (TM) from AM, and AM from multiple sclerosis (MS). Statistical tests were computed which classified correctly > or =90% of the patients with BM, TM, AM at a sum minimum of false positive plus false negative results, and which reached additionally > or =90% sensitivity and specificity. To discriminate BM from AM, CSF IL-6 test > or =500 ng/l and CSF IL-1 beta test > or =8 ng/l besides CSF lactate test > or =3.5mM/l and CSF granulocyte test > or =150 M/l were revealed. CSF lactate test > or =3.2 mmol/l discriminated TM from AM. CSF leukocyte test > or =35 M/l discriminated AM from MS. Tests with the new markers were more laborious, expensive, and time consuming compared to CSF lactate test. Test candidates, detecting > or =80% of patients with > or =80% sensitivity and specificity, were evaluated with CSF TNF-alpha, IL-8 and LBP, serum IL-6, CSF leukocytes, lymphocytes and monocytes, Qglucose, CSF total protein, albumin, and Qalbumin. All tests should be reviewed in context of clinical findings to diagnose BM reliably.

Pathophysiology of meningococcal meningitis and septicaemia

Neisseria meningitidis is remarkable for the diversity of interactions that the bacterium has with the human host, ranging from asymptomatic nasopharyngeal colonisation affecting virtually all members of the population; through focal infections of the meninges, joints, or eye; to the devastating and often fatal syndrome of meningococcal septic shock and purpura fulminans.

Absolute neutrophil count in aseptic and bacterial meningitis related to time of lumbar puncture

Previous studies have demonstrated that during the first 24 hours of illness caused by aseptic meningitis, polymorphonuclear cells predominate in cerebrospinal fluid and decline afterward. To test the hypothesis that the absolute neutrophil count and percentage of polymorphonuclear cells in cerebrospinal fluid of bacterial meningitis patients are elevated and sustained after 24 hours compared with that of patients with aseptic meningitis. Seventy-two patients with aseptic meningitis and 13 with bacterial meningitis participated. All patients with aseptic meningitis and four patients with bacterial meningitis were followed-up prospectively. The patients were enrolled in four groups according to the interval between onset of symptoms and performance of the lumbar puncture (<12 hours, 12-24 hours, 24-36 hours, and >36 hours). In aseptic meningitis the mean absolute neutrophil count was 182, 164, 79, and 68 cells/mm(3), respectively (P = 0.025). In bacterial meningitis the absolute neutrophil count was 28, 1,466, 5,853, and 235 cells/mm(3), respectively. The mean percentage of polymorphonuclear cells in aseptic meningitis was 49%, 46%, 40%, and 26%, respectively (P = 0.038); in bacterial meningitis, 70%, 83%, 81%, and 58%, respectively. The findings suggest that the absolute neutrophil count and the polymorphonuclear cell percentage in cerebrospinal fluid have different kinetics in aseptic vs. bacterial meningitis.

Inhibition of long-term potentiation by interleukin-8: implications for human immunodeficiency virus-1-associated dementia

Human immunodeficiency virus type 1 (HIV-1)-infected mononuclear phagocytes (MP; brain macrophages and microglia) secrete a number of toxic factors that affect the pathogenesis of HIV-1-associated dementia (HAD). The identification and relative role of each MP toxin for neuronal dysfunction during HAD are not well understood. Interleukin-8 (IL-8), a CXC chemokine involved in leukocyte activation and chemotaxis, is constitutively produced by MP, and elevated levels of IL-8 mRNA were detected in the brains of patients with HIV-1 encephalitis (HIVE) by both ribonuclease protection assays and real-time PCR. To determine the role that IL-8 might play in the neuronal dysfunction in HAD, we studied its effect on synaptic transmission and plasticity in the CA1 region of hippocampus, the seat of learning and memory. Bath application of IL-8 (50 ng/ml) to rat hippocampal slices had no effect on basal synaptic transmission. However, IL-8 was shown to inhibit long-term potentiation (LTP) in a concentration-dependent manner. In control and IL-8-treated slices, the LTP magnitudes were 167.8% +/- 11.9% (mean +/- SE; n = 17) and 122.2% +/- 16.2% of basal levels (n = 13), respectively. These differences were statistically significant (P < 0.05). Preincubation of hippocampal slices with a monoclonal CXCR2 antibody (2 microg/ml) but not control IgG (2 microg/ml) blocked IL-8-induced inhibition of LTP. The expression of CXCR2 receptors in the CA1 region was shown by Western blot assays. The induction of IL-8 in HAD, its inhibition of LTP, and the expression of its receptor, CXCR2, in the hippocampus all suggest that it plays a role in the cognitive dysfunction associated with HAD.

Circulating inflammatory mediators predict shock and mortality in febrile patients with microbial infection

The host response to microbial infection is associated with the release of inflammatory mediators. We hypothesized that the type and degree of the systemic response as reflected by levels of circulating mediators predict morbidity and mortality, according to the invasiveness of microbial infection. We prospectively studied 133 medical patients with fever and culture-proven microbial infection. For 3 days after inclusion, the circulating levels of activated complement C3a, interleukin (IL)-6, and secretory phospholipase A(2) (sPLA(2)) were determined daily. Based on results of microbiological studies performed for up to 7 days, patients were classified as having local infections (Group 1, n = 80 positive local cultures or specific stains for fungal or tuberculous infections) or bacteremia (Group 2, n = 52 plus 1 patient with malaria parasitemia). Outcome was assessed as the development of septic shock and as mortality up to 28 days after inclusion. Fifteen patients (11%) developed septic shock and overall mortality was 18% (n = 24). Bacteremia was associated with shock and shock predisposed to death. Circulating mediator levels were generally higher in Group 2 than in Group 1. Circulating levels of IL-6 and sPLA(2) were higher in patients developing septic shock and in nonsurvivors, particularly in Group 1. High C3a was particularly associated with nonsurvival in Group 2. In Group 1, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the peak sPLA(2) for shock development was 0.79 (P < 0.05). The AUC of the ROC curve of the peak IL-6 and sPLA(2) for mortality was 0.69 and 0.68 (P < 0.05), respectively. In Group 2, the AUC of the ROC for peak C3a predicting mortality was 0.73 (P < 0.05). In conclusion, in medical patients with fever and microbial infection, the systemic inflammatory host response predicts shock and death, at an early stage, dependent on the invasiveness of microbial infection. The results suggest a differential pathogenetic role of complement activation on the one hand and release of cytokine and lipid mediators on the other in bacteremic and local microbial infections, respectively. They may partly explain the failure of strategies blocking proinflammatory cytokines or sPLA(2) in human sepsis and may extend the basis for attempts to inhibit complement activation at an early stage in patients at risk of dying from invasive microbial infections.

Interaction of Neisseria meningitidis with human meningeal cells induces the secretion of a distinct group of chemotactic, proinflammatory, and growth-factor cytokines

The interactions of Neisseria meningitidis with cells of the leptomeninges are pivotal events in the progression of bacterial leptomeningitis. An in vitro model based on the culture of human meningioma cells was used to investigate the role of the leptomeninges in the inflammatory response. Following challenge with meningococci, meningioma cells secreted specifically the proinflammatory cytokine interleukin-6 (IL-6), the CXC chemokine IL-8, the CC chemokines monocyte chemoattractant protein 1 (MCP-1) and regulated-upon-activation, normal-T-cell expressed and secreted protein (RANTES), and the cytokine growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF). A temporal pattern of cytokine production was observed, with early secretion of IL-6, IL-8, and MCP-1 followed by later increases in RANTES and GM-CSF levels. IL-6 was induced equally by the interactions of piliated and nonpiliated meningococci, whereas lipopolysaccharide (LPS) had a minimal effect, suggesting that other, possibly secreted, bacterial components were responsible. Induction of IL-8 and MCP-1 also did not require adherence of bacteria to meningeal cells, but LPS was implicated. In contrast, efficient stimulation of RANTES by intact meningococci required pilus-mediated adherence, which served to deliver increased local concentrations of LPS onto the surface of meningeal cells. Secretion of GM-CSF was induced by pilus-mediated interactions but did not involve LPS. In addition, capsule expression had a specific inhibitory effect on GM-CSF secretion, which was not observed with IL-6, IL-8, MCP-1, or RANTES. Thus, the data demonstrate that cells of the leptomeninges are not inert but are active participants in the innate host response during leptomeningitis and that there is a complex relationship between expression of meningococcal components and cytokine induction.

Interleukin-8 levels in children with bacterial, tuberculous and aseptic meningitis

OBJECTIVE

lnterleukin-8 (IL-8) is produced in monocytes and vascular endothelial cells in response to stimulation with bacteria or lipopolysaccharides, and is released from these cells into blood stream or tissue fluid.

METHODS

Cerebrospinal fluid (CSF) levels of interleukin-8 in 56 children with nonbacterial, bacterial and tuberculous meningitis (TBM), and in 15 control subjects were analyzed to evaluate the involvement of this cytokine in the pathogenesis acute bacterial meningitis and their discriminative value between different etiologies of meningitis. The kinetics of IL-8 concentrations during the course of bacterial meningitis was also evaluated in patients. IL-8 levels were significantly higher in bacterial and TBM than in aseptic meningitis and in control subjects (p < 0.0001).

RESULTS

There was no difference in the levels of IL-8 between the non-bacterial meningitis and control groups. The analysis of the kinetics of production of IL-8 in patients with bacterial meningitis showed that the SSF concentrations of this cytokine decreased to undetectable values in recovery stage. Conversely in patients with TBM the concentrations of IL-8 were elevated in two weeks after beginning the specific treatment.

CONCLUSION

The results suggest that determining IL-8 levels may be useful in the differential diagnosis.

Outer membrane vesicles from Neisseria meningitidis: effects on cytokine production in human whole blood

The Norwegian group B meningococcal outer membrane vesicle (OMV) vaccine consists of outer membrane proteins (OMPs) as main antigens with significant amounts of lipopolysaccharide (LPS; 5-9% relative to protein). We have studied the ability of this OMV vaccine preparation to induce secretion of pro-inflammatory cytokines, tumour necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8) and anti-inflammatory cytokines, interleukin 4 (IL-4), interleukin 10 (IL-10) and interleukin 13 (IL-13) in a human whole blood model. Plasma levels of TNF-alpha, IL-1beta, IL-6 and IL-8 were massively increased; mean peak levels of TNF-alpha 44 696+/-7764, IL-1beta 38 043+/-5411, IL-6 10 057+/-1619 and IL-8 30 449+/-5397 pg/ml were obtained with an OMV-LPS concentration of 1 microg/ml; corresponding levels in control plasmas were below the detection limit of the assay. Mean maximal level of IL-10 (2540+/-144 pg/ml) was obtained at OMV-LPS concentration of 10 microg/ml, after 24 h; while the level in control plasma was below detection limit. OMV-LPS did not induce release of IL-4 and IL-13 in doses from 0.001-10 microg/ml. The present results show that OMVs from meningococci have potent pro-inflammatory properties and are likely to contribute to the observed local and systemic inflammatory effects.

Systemic neutralization of interleukin-8 markedly reduces neutrophilic pleocytosis during experimental lipopolysaccharide-induced meningitis in rabbits

Interleukin-8 (IL-8) is elevated in the cerebrospinal fluid (CSF) of patients with meningitis and is proposed to participate in subarachnoid-space pleocytosis. However, intracisternal injection of IL-8 into rabbits failed to induce indices typical of meningitis (leukocyte, tumor necrosis factor, or protein accumulation in the CSF or histopathological changes), indicating that merely increasing the CSF level of this chemokine is insufficient to induce inflammation in this anatomical site. IL-8 treatment did not affect inflammatory responses to subsequently intracisternally administered lipopolysaccharide (LPS). IL-8 was chemotactic for rabbit neutrophils in vitro, and subcutaneous injection of IL-8 (diluted in buffer or CSF) proved the in vivo activity of this peptide and suggested the absence of an IL-8 inhibitor in normal rabbit CSF. LPS-dependent pleocytosis was only slightly diminished by intracisternally administered murine anti-rabbit IL-8 monoclonal antibody (MAb) WS-4 but was dramatically reduced by intravenously administered MAb. Therefore, elevated CSF IL-8 levels may contribute to, but cannot solely account for, neutrophil influx into the subarachnoid space during meningitis. However, inhibition of IL-8 activity of the bloodstream side of the blood-brain barrier effectively reduces pleocytosis, indicating a central role of IL-8 in neutrophil influx into CSF during bacterial meningitis. Thus, inhibition of IL-8 is a possible therapeutic target for adjunct treatment of meningitis.

Plasma granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor levels in critical illness including sepsis and septic shock: relation to disease severity, multiple organ dysfunction, and mortality

OBJECTIVE

To define the circulating levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) during critical illness and to determine their relationship to the severity of illness as measured by the Acute Physiology and Chronic Health Evaluation (APACHE) II score, the development of multiple organ dysfunction, or mortality.

DESIGN

Prospective cohort study.

SETTING

University hospital intensive care unit.

PATIENTS

A total of 82 critically ill adult patients in four clinically defined groups, namely septic shock (n = 29), sepsis without shock (n = 17), shock without sepsis (n = 22), and nonseptic, nonshock controls (n = 14).

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

During day 1 of septic shock, peak plasma levels of G-CSF, interleukin (IL)-6, and leukemia inhibitory factor (LIF), but not GM-CSF, were greater than in sepsis or shock alone (p < .001), and were correlated among themselves (rs = 0.44-0.77; p < .02) and with the APACHE II score (rs = 0.25-0.40; p = .03 to .18). G-CSF, IL-6, and UF, and sepsis, shock, septic shock, and APACHE II scores were strongly associated with organ dysfunction or 5-day mortality by univariate analysis. However, multiple logistic regression analysis showed that only septic shock remained significantly associated with organ dysfunction and only APACHE II scores and shock with 5-day mortality. Similarly, peak G-CSF, IL-6, and LIF were poorly predictive of 30-day mortality.

CONCLUSIONS

Plasma levels of G-CSF, IL-6, and LIF are greatly elevated in critical illness, including septic shock, and are correlated with one another and with the severity of illness. However, they are not independently predictive of mortality, or the development of multiple organ dysfunction. GM-CSF was rarely elevated, suggesting different roles for G-CSF and GM-CSF in human septic shock.

sICAM-1 and TNF-alpha induce MIP-2 with distinct kinetics in astrocytes and brain microvascular endothelial cells

The dysfunction of the blood-brain barrier (BBB) occurring after traumatic brain injury (TBI) is mediated by intracerebral neutrophil accumulation, chemokine release (e.g., interleukin (IL)-8) and upregulation of adhesion molecules (e.g., intercellular adhesion molecule (ICAM)-1). In patients with severe TBI, we previously found that elevated cerebrospinal fluid (CSF) IL-8 and soluble (s)ICAM-1 correlate with BBB dysfunction, and this prompted us to concomitantly monitor IL-8, sICAM-1 and their stimulator tumor necrosis factor (TNF)-alpha in CSF. Potential mechanisms for upregulation of the IL-8 analogue, murine macrophage inflammatory protein (MIP)-2, and sICAM-1 at the BBB were studied using cultured mouse astrocytes and brain microvascular endothelial cells (MVEC). In CSF of seven patients, IL-8 and sICAM-1 were elevated for 19 days after severe TBI, whereas TNF-alpha exceeded normal values on 9 days. Stimulation of MVEC and astrocytes with TNF-alpha simultaneously induced the release of MIP-2 reaching saturation by 4-8 hr and of sICAM-1 increasing continuously from 2-4 hr to 12 hr. Augmented sICAM-1 production correlated with enhanced membrane-bound (m)ICAM-1 expression in both cell types (r(s) = 0.96 and 0.90, P < 0.0001), but was markedly higher in astrocytes. The release of sICAM-1 was not influenced by IL-8 or MIP-2, although astrocytes and MVEC expressed the IL-8/MIP-2 receptor (CXCR-2) as determined by FACS analysis. Instead, we found that sICAM-1 strongly induced MIP-2 secretion by both cell types with kinetics differing from those evoked by TNF-alpha. If added together, sICAM-1 and TNF-alpha synergistically induced MIP-2 production suggesting the involvement of two different pathways for MIP-2 regulation.

C-reactive protein, procalcitonin and interleukin-8 in the primary diagnosis of infections in cancer patients

The diagnostic utility of C-reactive protein (CRP), procalcitonin (PCT) and interleukin-8 (IL-8) were studied in 66 cancer patients with suspected infection (39 with definite foci of infection, 17 with antibiotic responses without foci and 10 with neoplastic fever without infection) and 26 patients scheduled for chemotherapy. The infection group (n=56) had higher median CRP (91 versus 19 mg/l, P<0. 001), PCT (0.28 versus 0.12 ng/ml, P<0.001) and IL-8 values (27.7 versus 16.9 pg/ml, P=0.032) than the non-infection group (n=36). In patients with suspected infection, only PCT was a good marker to discriminate bacteraemia with an area under the receiver operating characteristics curve of 0.92 (95% confidence interval (CI), 0.77-1. 0), but even PCT was less well able to differentiate between non-bacteraemic infections and neoplastic fever (0.56; 95% CI, 0. 35-0.77). In conclusion, PCT was a good indicator for bacteraemia, but none of the three markers were reliable indicators for minor infections in non-neutropenic cancer patients.

Interleukin-8 is increased in cerebrospinal fluid of children with severe head injury

OBJECTIVE

To determine interleukin (IL)-8 concentrations in ventricular cerebrospinal fluid from children with severe traumatic brain injury (TBI).

DESIGN

Prospective study.

SETTING

University children's hospital.

PATIENTS

Twenty-seven children hospitalized with severe TBI (Glasgow Coma Scale score < or =8), seven children with cerebrospinal fluid culture-positive bacterial meningitis, and twenty-four age-equivalent controls.

INTERVENTIONS

Placement of an intraventricular catheter and continuous drainage of cerebrospinal fluid.

MEASUREMENTS AND MAIN RESULTS

Median [range] cerebrospinal fluid IL-8 concentration in children with TBI (0-12 hrs) (4,452.5 [0-20,000] pg/mL) was markedly greater than that in controls (14.5 [0-250]) (p < .0001) and equivalent to concentrations in children with meningitis (5,300 [1,510-22,000] pg/mL) (p = .33). Cerebrospinal fluid IL-8 remained increased in children with severe TBI for up to 108 hrs after injury. Univariate logistic regression analysis demonstrated an association between cerebrospinal fluid IL-8 and child abuse (p = .07) and mortality (p = .01). Multivariate analysis demonstrated a strong, independent association between cerebrospinal fluid IL-8 and mortality (p = .01).

CONCLUSIONS

The data are consistent with an acute inflammatory component of TBI in children and suggest an association between cerebrospinal fluid IL-8 and outcome after TBI. IL-8 may represent a potential target for anti-inflammatory therapy.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.

Occult bacteremia in young febrile children

The evaluation of nontoxic-appearing, young, febrile children has been a subject of considerable debate. Of young, nontoxic-appearing children aged 3 to 36 months with temperatures of 39 degrees C or more and no clear source, approximately 2% to 3% have occult bacteremia. Of these bacteremias, approximately 90% are caused by S. pneumoniae, 5% by nontyphoidal Salmonella sp., and 1% by N. meningitidis. Most children with occult pneumococcal bacteremia improve spontaneously, but approximately 25% of untreated patients have persistent bacteremia or develop new focal infections, including 3% to 6% who develop meningitis. Occult meningococcal bacteremia, although rare, has frequent complications, including meningitis in approximately 40% and death in approximately 4%. Less is known about the natural history of untreated occult nontyphoidal Salmonella bacteremia. Empiric antibiotic treatment of children with occult bacteremia decreases the rate of complications, including meningitis. Few disagree that febrile, young children at risk for occult bacteremia require a careful clinical evaluation and close follow-up. The benefits of laboratory screening and selective empiric antibiotic treatment of febrile children at risk for occult bacteremia have to be weighed against the costs of screening tests and blood cultures, inconvenience, temporary discomfort to patients, risk for side effects of antibiotics, and the role of antibiotics in the development of bacterial resistance. Although great debate exists concerning the role of empiric antibiotics, a strategy for obtaining blood cultures and empirically administering antibiotics on the basis of an increased ANC, in addition to close clinical follow-up, may be effective in reducing the frequency and severity of uncommon but adverse sequelae. A highly effective S. pneumoniae bacterial conjugate vaccine will soon be available, which will benefit all children, and will alter the ways that clinicians evaluate fully immunized young, febrile children.

Matrix metalloproteinases contribute to the blood-brain barrier disruption during bacterial meningitis

In this study, we investigated the involvement of matrix metalloproteinases (MMPs) in the pathophysiology of bacterial meningitis. By using an enzyme immunoassay, high concentrations of MMP-9 were detected in the cerebrospinal fluid (CSF) of adult patients with bacterial meningitis but not in controls, and in patients with Guillain-Barré syndrome. Moreover, we observed significantly elevated concentrations of the tissue inhibitor of metalloproteinase-1 (TIMP-1) in the CSF of patients with bacterial meningitis, compared with controls. In a rat model of meningococcal meningitis, intracisternal injection of heat-killed meningococci caused a disruption of the blood-brain barrier (BBB), an increase in intracranial pressure, and CSF pleocytosis paralleled by the occurrence of MMP-9 activity in the CSF 6 hours after meningococcal challenge. The MMP inhibitor batimastat (BB-94) significantly reduced the BBB disruption and the increase in intracranial pressure irrespective of the time of batimastat administration (15 minutes before and 3 hours after meningococcal challenge) but failed to significantly reduce CSF white blood cell counts. In conclusion, our results suggest that MMPs are involved in the alterations of BBB permeability during experimental meningococcal meningitis.

Interleukin-8 and markers of neutrophil degranulation in pleural effusions

In order to know the degree of interleukin-8 (IL-8) production in the pleural space and its relationship to neutrophil activation, IL-8, neutrophil elastase (NE), and myeloperoxidase (MPO) were assessed in blood and pleural fluid (PF) of 219 patients with pleural effusions. Correlations between blood and PF IL-8, NE, and MPO were either absent or weak, except for IL-8 in transudates (r = 0.6745, p < 0.001). PF IL-8, NE, and MPO concentrations in cases of empyema were higher than in cases of effusion of other causes (p < 0.001). No significant differences in inflammatory markers were observed between parapneumonic and tuberculous fluids. IL-8, NE, and MPO levels in malignant, nonspecific, and transudative effusions were lower than in those due to infection, the lowest levels corresponding to transudates. No significant correlation was observed between PF IL-8 and neutrophil count in any group; in contrast, IL-8 was associated with NE and MPO in empyema (r = 0.7545, and r = 0.7283; p < 0.001), tuberculosis (r = 0.4016, p = 0.008 and r = 0.6545, p < 0.001), and nonspecific effusions (r = 0.3748, p = 0.007 and r = 0.3085, p = 0.028). Our results indicate that local production of markers of the nonspecific inflammatory response is high in both chronic and acute pleural infection, and suggest a role for IL-8 in the release of NE and MPO.

Cytokine Regulation of Human Microglial Cell IL-8 Production

IL-8 involvement in neutrophil activation and chemotaxis may be important in inflammatory responses within the central nervous system, secondary to meningitis, encephalitis, and traumatic injury. The source of IL-8 within the brain during these inflammatory processes, however, is unknown. To explore the role of microglia in the production of IL-8, human fetal microglia, which are the resident macrophages of the brain, were treated with LPS and pro- and anti-inflammatory cytokines to determine their effects on IL-8 production. We found that IL-8 protein levels increased in response to LPS or IL-1β, or to TNF-α, which also corresponded to elevated IL-8 mRNA levels by RT-PCR. Pretreatment with IL-4, IL-10, or TGF-β1 potently inhibited the stimulatory effects of these proinflammatory agents. These findings indicate that human microglia synthesize IL-8 in response to proinflammatory stimuli, and that anti-inflammatory cytokines down-regulate the production of this chemokine. These results may have important therapeutic implications for certain central nervous system insults involving inflammation.

The production of macrophage inflammatory protein-1alpha in the cerebrospinal fluid at the initial stage of meningitis in children

Neutrophils in the cerebrospinal fluid (CSF) increase during the initial stage of meningitis. Some cytokines induce the accumulation of such neutrophils, and we and other investigators have revealed transient increases in the levels of granulocyte-colony stimulating factor (G-csf) and IL-8 in the CSF of patients with meningitis. To explore the coordination of other cytokines with G-csf and IL-8 in the neutrophil accumulation in the CSF, we herein investigated macrophage inflammatory protein-1alpha (MIP-1alpha), which can induce the infiltration of neutrophils. The modulation of MIP-1alpha levels in the CSF in children with bacterial (n = 10) and aseptic (n = 22) meningitis was examined using an ELISA. MIP-1alpha levels in the CSF were detectable at the stage with symptoms of meningitis: 289.9 +/- 270.7 ng/L in the bacterial meningitis group and 16.1 +/- 12.5 ng/L in the aseptic meningitis group. These levels decreased with the improvement of symptoms. MIP-1alpha was not detectable (<6 ng/L) in all of the control patients without meningitis (n = 19). The MIP-1alpha levels in the CSF showed a significant correlation with the CSF neutrophil counts (r = 0.750, p < 0.0001; n = 80) of meningitis, and the values of MIP-1alpha (log ng/L)/neutrophil counts (log/L) ratio were calculated (1.003 +/- 0.576). The MIP-1alpha levels in the serum were significantly lower than those in the CSF (p = 0.0464). We found MIP-1alpha mRNA in the CSF cells by the reverse transcriptase-PCR method, and high levels of MIP-1alpha protein in the culture media from mononuclear cells in the CSF in vitro. In summary, The MIP-1alpha level increases in the CSF at the symptomatic stage of meningitis in children, and its cellular source is, in part, mononuclear cells which have infiltrated the CSF. We propose that MIP-1alpha, in addition to G-csf and IL-8, plays an important role in the accumulation of neutrophils in the CSF of patients with meningitis.

The Pattern of Interleukin-1β (IL-1β) and Its Modulating Agents IL-1 Receptor Antagonist and IL-1 Soluble Receptor Type II in Acute Meningococcal Infections

Interleukin-1β (IL-1β) is considered an important mediator in the pathogenesis of septic shock or bacterial meningitis. Its activity is specifically modulated by IL-1 receptor antagonist (IL-1Ra) and IL-1 soluble receptor type II (IL-1sRII). We now describe the time-course of IL-1β and these modulating agents in 59 patients with acute meningococcal infections, the prototype human disease of acute endotoxin exposure. Plasma IL-1β was increased only in severe shock and normalized within 12 to 24 hours, indicating that patients were admitted in an early stage of cytokine activation. Increased IL-1β values in cerebrospinal fluid (CSF ) were confined to patients with meningitis. Plasma IL-1Ra was elevated in both shock and nonshock patients, extremely high values being measured in severe shock. High concentrations of IL-1Ra in CSF were found in meningitis. Plasma IL-1Ra peaked shortly after IL-1β and decreased steeply in 1 to 2 days, followed by sustained moderately elevated levels in shock patients. Interestingly, IL-1sRII showed a completely different pattern. At admission, both nonshock and shock patients manifested a similar moderate increase of plasma IL-1sRII. However, during recovery plasma IL-1sRII further increased reaching maximal concentrations 3 to 5 days after admission, 1 to 2 days after normalization of IL-1Ra. In shock patients this increase was more prominent than in nonshock patients. It is hypothesized that this increase in plasma IL-1sRII can be explained by a synergistic effect of dexamethasone and endotoxin. A second interesting observation was that, unlike the pattern in plasma, IL-1sRII levels in CSF paralleled those of IL-1β and IL-1Ra. This suggests different modulation of IL-1β activity in the subarachnoid space and the plasma compartment. We conclude that: (1) During the early stage of meningococcal infections IL-1Ra modulates IL-1 activity, whereas during recovery IL-1sRII may be more important. (2) Modulation in CSF and in the plasma compartment are differentially regulated.

The Pattern of Interleukin-1β (IL-1β) and Its Modulating Agents IL-1 Receptor Antagonist and IL-1 Soluble Receptor Type II in Acute Meningococcal Infections

Interleukin-1β (IL-1β) is considered an important mediator in the pathogenesis of septic shock or bacterial meningitis. Its activity is specifically modulated by IL-1 receptor antagonist (IL-1Ra) and IL-1 soluble receptor type II (IL-1sRII). We now describe the time-course of IL-1β and these modulating agents in 59 patients with acute meningococcal infections, the prototype human disease of acute endotoxin exposure. Plasma IL-1β was increased only in severe shock and normalized within 12 to 24 hours, indicating that patients were admitted in an early stage of cytokine activation. Increased IL-1β values in cerebrospinal fluid (CSF ) were confined to patients with meningitis. Plasma IL-1Ra was elevated in both shock and nonshock patients, extremely high values being measured in severe shock. High concentrations of IL-1Ra in CSF were found in meningitis. Plasma IL-1Ra peaked shortly after IL-1β and decreased steeply in 1 to 2 days, followed by sustained moderately elevated levels in shock patients. Interestingly, IL-1sRII showed a completely different pattern. At admission, both nonshock and shock patients manifested a similar moderate increase of plasma IL-1sRII. However, during recovery plasma IL-1sRII further increased reaching maximal concentrations 3 to 5 days after admission, 1 to 2 days after normalization of IL-1Ra. In shock patients this increase was more prominent than in nonshock patients. It is hypothesized that this increase in plasma IL-1sRII can be explained by a synergistic effect of dexamethasone and endotoxin. A second interesting observation was that, unlike the pattern in plasma, IL-1sRII levels in CSF paralleled those of IL-1β and IL-1Ra. This suggests different modulation of IL-1β activity in the subarachnoid space and the plasma compartment. We conclude that: (1) During the early stage of meningococcal infections IL-1Ra modulates IL-1 activity, whereas during recovery IL-1sRII may be more important. (2) Modulation in CSF and in the plasma compartment are differentially regulated.

Interleukin-8 released into the cerebrospinal fluid after brain injury is associated with blood-brain barrier dysfunction and nerve growth factor production

Interleukin (IL) 8 was measured in CSF of 14 patients with severe traumatic brain injury. IL-8 levels were significantly higher in CSF (up to 8,000 pg/ml) than serum (up to 2,400 pg/ml) (p < 0.05), suggesting intrathecal production. Maximal IL-8 values in CSF correlated with a severe dysfunction of the blood-brain barrier. Nerve growth factor (NGF) was detected in CSF of 7 of 14 patients (range of maximal NGF: 62-12,130 pg/ml). IL-8 concentrations were significantly higher in these patients than in those without NGF (p < 0.01). CSF containing high IL-8 (3,800-7,900 pg/ml) induced greater NGF production in cultured astrocytes (202-434 pg/ml) than samples with low IL-8 (600-1,000 pg/ml), which showed a smaller NGF increase (0-165 pg/ml). Anti-IL-8 antibodies strongly reduced (52-100%) the release of NGF in the group of high IL-8, whereas in the group with low IL-8, this effect was lower (0-52%). The inability of anti-IL-8 antibodies to inhibit the synthesis of NGF completely may depend on cytokines like tumor necrosis factor alpha and IL-6 found in these CSF samples, which may act in association with IL-8. Thus, IL-8 may represent a pivotal cytokine in the pathology of brain injury.

Different release of cytokines into the cerebrospinal fluid following surgery for intra- and extra-axial brain tumours

To elucidate the role of cytokines in brain repair processes and in local inflammation after neurosurgical procedures, cerebrospinal fluid (CSF) samples from 8 patients with intra-axial tumours and 8 patients with extra-axial tumours were analysed for interleukin (IL)-1 beta, IL-1 receptor antagonist (IL-1 ra), IL-6, IL-8, IL-10, and tumour necrosis factor (TNF)-alpha at the beginning and after surgery. Levels of IL-6 and IL-8 increased dramatically in all patients just hours after surgery and fell during subsequent days. IL-1 beta was found only in low amounts in the CSF of both patient groups. Other cytokines demonstrated different courses. In patients with intra-axial tumours IL-1 ra peaked two to four hours after surgery with a subsequent decrease. In patients with extra-axial tumours there was a continuous low-level IL-1 ra release into the CSF without a peak. TNF-alpha was not present in detectable levels in the CSF after surgery for extra-axial tumours but was found to peak two to four hours after surgery for intra-axial tumours. IL-10 was detected in the CSF of both patient groups, but a higher peak was seen after surgery for extra-axial tumours. These results suggest different requirements for the cytokine response and an involvement of different cell types in cytokine release. However, the analysis of the CSF from both patient groups showed no differences in cell counts and populations, with a mild pleocytosis being present in both patient groups after surgery. Therefore, we conclude that after surgery for extra-axial tumours cytokines were predominately produced by non-immune cells stimulated through hypoxia or mechanical irritation. After surgery for intra-axial tumours with a significant brain injury immune cells-activated by necrotic material-seen to be involved in the process of cytokine synthesis. In these cases an additional IL-1ra and TNF-alpha peak was found and these cytokines may be markers for cerebral injury.