Measurement of levels of tumor necrosis factor-alpha and interleukin-1 beta in the CSF of patients with meningitis of different etiologies: utility in the differential diagnosis

Immunologic biomarkers for bacterial meningitis

Meningitis is defined as the inflammation of the meninges that is most often caused by various bacterial and viral pathogens, and is associated with high rates of mortality and morbidity. Early detection of bacterial meningitis is essential to appropriate antibiotic therapy. Alterations in immunologic biomarkers levels have been considered the diagnostic approach in medical laboratories for the identifying of infections. The early increasing immunologic mediators such as cytokines and acute phase proteins (APPs) during bacterial meningitis have made they significant indicators for laboratory diagnosis. Immunology biomarkers showed wide variable sensitivity and specificity values that influenced by different reference values, selected a certain cutoff point, methods of detection, patient characterization and inclusion criteria, as well as etiology of meningitis and time of CSF or blood specimens' collection. This study provides an overview of different immunologic biomarkers as diagnostic markers for the identification of bacterial meningitis and their efficiencies in the differentiating of bacterial from viral meningitis.

TNF-α blockade suppresses pericystic inflammation following anthelmintic treatment in porcine neurocysticercosis

Background

Neurocysticercosis (NCC) is an infection of the brain with the larval cyst of the tapeworm, Taenia solium. Cysticidal treatment induces parasite killing resulting in a post inflammatory response and seizures, which generally requires corticosteroid treatment to control inflammation. The nature of this response and how to best control it is unclear. We investigated the anti-inflammatory effects of pretreatment with etanercept (ETN), an anti-tumor necrosis factor agent, or dexamethasone (DEX), a high potency corticosteroid, on the post treatment inflammatory response in naturally infected pigs with neurocysticercosis after a single dose of the cysticidal drug praziquantel (PZQ).

Methodology/Principal findings

We followed the methods from a previously developed treatment model of NCC in naturally infected swine. The four study groups of infected pigs included 3 groups treated with PZQ on day 0: PZQ-treated alone (100 mg/kg PO; n = 9), pretreated with dexamethasone (DEX, 0.2 mg/kg IM administered on days -1, +1 and +3; n = 6), and pretreated with etanercept (ETN, 25 mg IM per animal on days -7 and 0; n = 6). The fourth group remained untreated (n = 3). As measured by quantitative RT-PCR, ETN pretreatment depressed transcription of a wide range of proinflammatory, regulatory and matrix protease encoding genes at 120 hr post PZQ treatment in capsules of cysts that demonstrated extravasated Evans Blue (EB) (a measure of blood brain barrier dysfunction) compared to animals not receiving ETN. Transcription was significantly depressed for the proinflammatory genes tumor necrosis factor (TNF)-α, and interferon (IFN)-γ; the inflammation regulating genes cytotoxic T-lymphocyte-associated protein (CTLA)4, interleukin (IL)-13 and transforming growth factor (TGF)-β; the tissue remodeling genes matrix metalloprotease (MMP)1 and 9, tissue inhibitors of metalloproteases (TIMP)1 and 2, and the genes regulating endothelial function vascular endothelial growth factor (VEGF)1, angiopoietin (Ang)1, Ang 2, and platelet endothelial cell adhesion molecule (PECAM)-1. In contrast, transcription was only modestly decreased in the DEX pretreated pigs compared to PZQ alone, and only for TNF-α, IL-6, IFN-γ, TGF-β and Ang1. IL-10 was not affected by either ETN or DEX pretreatments. The degree of inflammation, assessed by semi-quantitative inflammatory scores, was modestly decreased in both ETN and DEX pretreated animals compared to PZQ treated pigs whereas cyst damage scores were moderately decreased only in cysts from DEX pretreated pigs. However, the proportion of cysts with EB extravasation was not significantly changed in ETN and DEX pretreated groups.

Conclusions/Significance

Overall, TNF-α blockade using ETN treatment modulated expression of a large variety of genes that play a role in induction and control of inflammation and structural changes. In contrast the number of inflammatory cells was only moderately decreased suggesting weaker effects on cell migration into the inflammatory capsules surrounding cysts than on release of modulatory molecules. Taken together, these data suggest that TNF-α blockade may provide a viable strategy to manage post-treatment pericystic inflammation that follows antiparasitic therapy for neurocysticercosis.

Infection of the brain with larvae of the tapeworm Taenia solium is called neurocysticercosis (NCC), a disease with varied and serious neurological symptoms. Therapy requires antiparasitic drugs and corticosteroids to prevent seizures caused by treatment due to inflammation around dying parasites. The gene expression of the proinflammatory molecule tumor necrosis factor alpha (TNF-α) is increased in NCC. We treated three groups of naturally infected pigs with an antiparasitic drug: one group was also pretreated with an anti-TNF-α inhibitor, the second one with a corticosteroid, and the third was not pretreated. All pigs were infused with Evans blue dye (EB), which leaks where the blood brain barrier is damaged by inflammation around cysts. We compared the expression of several genes involved in inflammation, healing and fibrosis and regulation of vascular function in tissues surrounding cysts. In inflamed samples showing leaked EB, the inhibition of TNF-α suppressed nearly all the genes assessed, and this suppression was significantly stronger than the moderate decrease caused by corticosteroid pretreatment on most of the genes. On microscopic examination, the inflammation observed was slightly decreased with both pretreatments in relation to the group that was not pretreated. We believe that the inflammatory route that includes TNF-α should be further explored in the search for better management of inflammation directed to degenerating cysts.

Treatment strategies for central nervous system infections: an update

INTRODUCTION

Central nervous system infection continues to be an important cause of mortality and morbidity worldwide. Our incomplete knowledge on the pathogenesis of how meningitis-causing pathogens cause CNS infection and emergence of antimicrobial resistance has contributed to the mortality and morbidity. An early empiric antibiotic treatment is critical for the management of patients with bacterial meningitis, but early recognition of bacterial meningitis continues to be a challenge.

AREAS COVERED

This review gives an overview on current therapeutic strategies for CNS infection with a focus on recent literature since 2010 on bacterial meningitis. Bacterial meningitis is a medical emergency, requiring early recognition and treatment. The selection of appropriate empiric antimicrobial regimen, after incorporating the epidemiology of bacterial meningitis, impact of vaccination, emergence of antimicrobial-resistant bacteria, role of adjunctive therapy and the current knowledge on the pathogenesis of meningitis and associated neuronal injury are covered.

EXPERT OPINION

Prompt treatment of bacterial meningitis with an appropriate antibiotic is essential. Optimal antimicrobial treatment of bacterial meningitis requires bactericidal agents able to penetrate the blood-brain barrier, with efficacy in cerebrospinal fluid. Emergence of CNS-infecting pathogens with resistance to conventional antibiotics has been increasingly recognized, but development of new antibiotics has been limited. More complete understanding of the microbial and host factors that are involved in the pathogenesis of bacterial meningitis and associated neurologic sequelae is likely to help in developing new strategies for the prevention and therapy of bacterial meningitis.

Characterization of DNase activity and gene in Streptococcus suis and evidence for a role as virulence factor

Background

The Gram-positive bacterium Streptococcus suis serotype 2 is an important swine pathogen and emerging zoonotic agent. Multilocus sequence typing allowed dividing S. suis serotype 2 into sequence types (STs). The three major STs of S. suis serotype 2 from North America are 1 (most virulent), 25 (intermediate virulence) and 28 (less virulent). Although the presence of DNase activity in S. suis has been previously reported, little data is available. The aim of this study was to investigate DNase activity in S. suis according to STs, to characterize the activity and gene, and to provide evidence for a potential role in virulence.

Results

We showed that ST1 and ST28 strains exhibited DNase activity that was absent in ST25 strains. The lack of activity in ST25 isolates was associated with a 14-bp deletion resulting in a shifted reading frame and a premature stop codon. The DNase of S. suis P1/7 (ST1) was cell-associated and active on linear DNA. A DNase-deficient mutant of S. suis P1/7 was found to be less virulent in an amoeba model. Stimulation of macrophages with the DNase mutant showed a decreased secretion of pro-inflammatory cytokines and matrix metalloproteinase-9 compared to the parental strain.

Conclusions

This study further expands our knowledge of S. suis DNase and its potential role in virulence.

The Expression of Interleukin-1b and miRNA-146a in the Cerebral Cortex of Acute Escherichia Coli Meningitis Immature Rat Model

The main limitation to advances in treatment of bacterial meningitis and its complications is the incomplete knowledge of the pathogenesis and pathophysiology of this disease. The aim of this research is to detect the expression of interleukin (IL)-1β as pro-inflammatory cytokine and miRNA (miR)-146a as post transcriptional inflammation associated microRNA (miRNA) in the cerebral cortex of acute Escherichia coli (E. coli) meningitis immature rat model. Immature rats in the post natal day 11 (PN11) were used to construct a model of acute E. coli meningitis and served as controls. The expression of IL-1β and miR-146a were detected in the cerebral cortex by reverse transcription polymerase chain reaction (RT-PCR) and real-time quantitative PCR (qPCR) analysis respectively, 24 hours after bacterial inoculation. In the cerebral cortical tissue of acute E. coli meningitis immature rat model the IL-1β expression was significantly upregulated while the miR-146a expression was significantly downregulated. This study tried to add a new insight on the molecular basis of the E. coli meningitis pathogenesis at its very early stage through detecting the expression of IL-1β and miR-146a in the cerebral cortex of the infected immature rats. Consequently, modulation of the IL-1β- miR-146a axis may be a new target for treatment of acute E. coli meningitis.

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.

The SspA subtilisin-like protease of Streptococcus suis triggers a pro-inflammatory response in macrophages through a non-proteolytic mechanism

Background

Streptococcus suis is a major swine pathogen worldwide that causes meningitis, septicemia, arthritis, and endocarditis. Using animal models, a surface-associated subtilisin-like protease (SspA) has recently been shown to be an important virulence factor for S. suis. In this study, we hypothesized that the S. suis SspA subtilisin-like protease may modulate cytokine secretion by macrophages thus contributing to the pathogenic process of meningitis.

Results

Phorbol 12-myristate 13-acetate-differentiated U937 macrophages were stimulated with recombinant SspA prior to monitor cytokine secretion by ELISA. Our results indicated that the recombinant SspA was able to dose-dependently induce IL-1β, IL-6, TNF-α, CXCL8 and CCL5 secretion in macrophages. The heat-inactivated protease was still able to induce cytokine secretion suggesting a non-proteolytic mechanism of macrophage activation. Using specific kinase inhibitors, evidence were bought that cytokine secretion by macrophages stimulated with the recombinant SspA involves the mitogen-activated protein kinase signal transduction pathway. While stimulation of macrophages with low concentrations of recombinant SspA was associated to secretion of high amounts of CCL5, the use of recombinant SspA at a high concentration resulted in low amounts of CCL5 detected in the conditioned medium. This was found to be associated with a proteolytic degradation of CCL5 by SspA. The ability of SspA to induce cytokine secretion in macrophages was confirmed using a mutant of S. suis deficient in SspA expression.

Conclusion

In conclusion, this study identified a new mechanism by which the S. suis SspA may promote central nervous system inflammation associated with meningitis.

Adhesion molecule levels in serum and cerebrospinal fluid in children with bacterial meningitis and sepsis

BACKGROUND

Adhesion molecules play a role in leukocyte recruitment during central nervous system (CNS) inflammation.

AIM

This study was designed to compare serum, cerebrospinal fluid (CSF) concentrations of adhesion molecules in children with meningitis and sepsis, and to evaluate their sources.

SETTING

This study was carried out at Pediatric Department, King Abdulaziz University Hospital from January 2007 to June 2008.

DESIGN

Serum and CSF samples were collected on admission from meningitis (n = 40), sepsis (n = 20) patients, and sera from controls (n = 20).

MATERIALS AND METHODS

Endothelial (E), leukocyte (L), platelet (P) selectins intercellular cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecules-1 (VCAM-1) were measured using ELISA.

STATISTICS

ANOVA and Spearman's correlations were used. Adhesion molecules with albumin concentration were estimated in CSF/serum to calculate concentration quotients.

RESULTS

In meningitis, serum sE-, sL-, sP-selectins sICAM-1, sVCAM-1 levels were higher than controls. Compared to sepsis, serum sE-selectin, sL-selectin, sVCAM-1, CSF-sL-selectin, CSF-sVCAM-1, VCAM-1 ratio and index were higher, while serum sP-selectin was lower than meningitis. sE-selectin ratio, CSF sICAM-1 were higher in meningitis with positive than negative culture. The sE-selectin index was higher in meningitis with neurological complication than those without it. In meningitis, correlation was found between CSF protein and CSF white blood cell counts (WBCs), CSF sICAM-1, CSF sVCAM-1 and between CSF sE-selectin and CSF sICAM-1.

CONCLUSIONS

This study supports the role of adhesion molecules especially sL-selectin, sVCAM-1 in meningitis and suggests further research to determine their use as biomarkers for meningitis and use of their antagonists as therapeutic for CNS inflammation. The presence of discrepancy of CSF/serum ratios for molecules of same molecular weight suggest intrathecal shedding in addition to diffusion through the blood-CSF barrier.

Hemoglobin and Streptococcus suis cell wall act in synergy to potentiate the inflammatory response of monocyte-derived macrophages

Streptococcus suis, a major swine pathogen world-wide, can trigger macrophages to secrete large amounts of proinflammatory cytokines, which increase the permeability of the blood—brain barrier. In this study, we hypothesized that hemoglobin may potentiate the inflammatory response of human macrophages stimulated with a S. suis cell-wall preparation. Monocyte-derived macrophages were stimulated with the S. suis cell-wall preparation in the presence or absence of human hemoglobin, and the secretion of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6, and IL-8 was analyzed by enzyme-linked immunosorbent assays. The cell-wall preparation induced dose-dependent IL-1β, TNF-α, IL-6, and IL-8 responses in macrophages. Hemoglobin potentiated the cell-wall induced inflammatory response, resulting in a significantly higher secretion of all the cytokines. The S. suis cell-wall preparation in combination with hemoglobin activated macrophage intracellular kinases involved in inflammatory signaling pathways. In conclusion, hemoglobin, which may be released in vivo by the action of S. suis suilysin on red blood cells, contributes to raising the levels of pro-inflammatory mediators by acting in synergy with S. suis cell-wall components. This phenomenon may contribute to the development and the severity of meningitis.

Lack of value of routine analysis of cerebrospinal fluid for prediction and diagnosis of external drainage–related bacterial meningitis

Object

Routine microbiological and chemical analysis of cerebrospinal fluid (CSF) is often performed to diagnose external drainage–related bacterial meningitis (ED-BM) at an early stage. A cohort study was performed to investigate the value of several commonly used CSF parameters for the prediction and diagnosis of ED-BM.

Methods

In a cohort of 230 consecutive patients in whom external drains had been placed, CSF samples were collected daily, prospectively evaluated for the presence of bacteria using Gram stain and microbiological culture, and analyzed for leukocyte count, protein concentration, glucose concentration, and ratio of CSF glucose to blood glucose. In addition, the CSF concentration of interleukin-6 (IL-6) was determined. The definition of ED-BM was based on positive culture results in combination with clinical symptoms. A matched case–control study was performed to evaluate the cohort longitudinally and to control for biasing factors such as duration of external drainage.

External drainage–related bacterial meningitis developed in 22 patients (9.6%). Results from analyses of 1516 CSF samples showed no significant differences between the patients in whom ED-BM developed and a control group without ED-BM during the first 3 days of infection or during the 3 days preceding the infection with regard to leukocyte count, protein concentration, glucose concentration, and CSF/blood glucose ratio. No significant difference between groups was found for the CSF IL-6 concentration during the 3 days preceding the infection. In the matched case–control study, none of the parameters had significant predictive or diagnostic value for ED-BM in analyses using absolute values, ratios, and differences between the current and previous day’s values. A comparison of the results from Gram stains and CSF cultures showed that the Gram staining had a very high specificity (99.9%) but a low sensitivity (18% [four of 22 patients] on the 1st day of infection and 60% [nine of 15 patients] on the 2nd day).

Conclusions

Severe disturbances in the CSF of patients with external drains limit the value of routine CSF analysis for prediction or diagnosis of ED-BM. Routine Gram stain of CSF has also limited predictive or diagnostic value due to its low sensitivity in screening for ED-BM.

Differential regulation of type I and type II interleukin-1 receptors in focal brain inflammation

Most pathologies of the brain have an inflammatory component, associated with the release of cytokines such as interleukin-1beta (IL-1beta) from resident and infiltrating cells. The IL-1 type I receptor (IL-1RI) initiates a signalling cascade but the type II receptor (IL-1RII) acts as a decoy receptor. Here we have investigated the expression of IL-1beta, IL-1RI and IL-1RII in distinct inflammatory lesions in the rat brain. IL-1beta was injected into the brain to generate an inflammatory lesion in the absence of neuronal cell death whereas neuronal death was specifically induced by the microinjection of N-methyl-D-aspartate (NMDA). Using TaqMan RT-PCR and ELISA, we observed elevated de novo IL-1beta synthesis 2 h after the intracerebral microinjection of IL-1beta; this de novo IL-1beta remained elevated 24 h later. There was a concomitant increase in IL-1RI mRNA but a much greater increase in IL-1RII mRNA. Immunostaining revealed that IL-1RII was expressed on brain endothelial cells and on infiltrating neutrophils. In contrast, although IL-1beta and IL-1RI were elevated to similar levels in response to NMDA challenge, the response was delayed and IL-1RII mRNA expression was unchanged. The lesion-specific expression of IL-1 receptors suggests that the receptors are differentially regulated in a manner not directly related to the endogenous level of IL-1 in the CNS.

Increased diffusion of soluble adhesion molecules in meningitis, severe sepsis and systemic inflammatory response without neurological infection is associated with intrathecal shedding in cases of meningitis

OBJECTIVE

Sepsis and systemic inflammatory response syndrome (SIRS) result in the release in plasma of inflammatory cytokines and soluble forms of adhesion molecules in relation to endothelial activation. This study was designed to compare cerebrospinal fluid (CSF) concentrations of adhesion molecules in meningitis and SIRS without neurological infection and to evaluate in meningitis whether they originate from passive diffusion through damaged blood-CSF barrier or from local production.

DESIGN

Prospective observational study.

SETTING

University hospital medical intensive care unit.

PATIENTS

Nineteen patients with meningitis and 41 patients with sepsis or SIRS without cerebrospinal infection consecutively admitted to the critical care unit over an 18-month period.

INTERVENTIONS

Soluble forms of adhesion molecules (ICAM-1, VCAM-1, E-selectin) and cytokines (interleukin (IL)-1beta and TNF-alpha) were measured in paired CSF and blood samples.

RESULTS

Serum concentrations of soluble adhesion molecules and cytokines were increased in the two groups, without significant differences. The CSF concentrations were elevated in both cases, whereas patients with meningitis demonstrated significantly higher CSF concentrations of soluble ICAM-1, VCAM-1, E-selectin, and TNF-alpha ( p<0.001), with higher corresponding CSF/serum ratios. Correlations between CSF and serum concentrations were found only in meningitis. These correlations were strong for soluble ICAM-1 (r(2)=0.7, p<0.001) and E-selectin (r(2)=0.9, p<0.001), but weaker for VCAM-1. VCAM-1 CSF/serum ratios were increased, in comparison with ICAM-1 and E-selectin CSF/serum ratios, despite similar molecular weights. Serum and CSF levels of cytokines and adhesion molecules were not predictive of death for the whole population, except concentrations of ICAM-1 significantly increased in non-surviving patients ( p<0.05).

CONCLUSIONS

The CSF soluble adhesion molecules are increased in sepsis, SIRS and meningitis. In meningitis, the correlation between CSF and serum concentrations of adhesion molecules and the presence of a discrepancy of CSF/serum ratios for molecules of the same molecular weight may suggest intrathecal shedding in addition to diffusion through blood-CSF barrier.

Cytokine profile in cerebrospinal fluid of children with echovirus type 4 meningitis

Cytokines play a role in meningeal inflammation and leukocyte recruitment. Research has demonstrated that levels of different cytokines are elevated in aseptic and viral meningitis. Unfortunately, previous data were confounded by the inclusion of multiple viral agents as a study group. The aims of the study were to determine the cerebrospinal fluid concentrations of various cytokines in an outbreak of a single viral agent and to correlate between cytokine levels and leukocytes. Cerebrospinal fluid samples, collected during an outbreak of echovirus type 4 meningitis in infants and children in Israel, were tested for routine characteristics. In addition, cytokine levels were measured in 71 meningitis patients and compared with those of 11 nonmeningitis patients. Concentrations of interleukin-6 (2417 +/- 2713 vs 28 +/- 20 pg/mL; P < 0.01) and interferon gamma (36 +/- 38 vs 4.8 +/- 0.9 pg/mL; P < 0.01) were significantly higher in patients with meningitis than in the control group, whereas soluble intercellular adhesion molecule-1 (1.12 +/- 2.6 vs 0.06 +/- 0.1 ng/mL) levels did not differ significantly. In addition, only interleukin-6 levels correlated with leukocyte counts in viral meningitis patients. Interleukin-6 was the most sensitive and specific characteristic in predicting meningitis in this homogeneous group of patients. Furthermore, only interleukin-6 correlated with leukocyte counts in the cerebrospinal fluid.

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.

IL-1 receptor type 1 gene-deficient mice demonstrate an impaired host defense against pneumococcal meningitis

The fatality rate associated with Streptococcus pneumoniae meningitis remains high despite adequate antibiotic treatment. IL-1 is an important proinflammatory cytokine, which is up-regulated in brain tissue after the induction of meningitis. To determine the role of IL-1 in pneumococcal meningitis we induced meningitis by intranasal inoculation with 8 x 10(4) CFU of S. pneumoniae and 180 U of hyaluronidase in IL-1R type I gene-deficient (IL-1R(-/-)) mice and wild-type mice. Meningitis resulted in elevated IL-1alpha and IL-1beta mRNA and protein levels in the brain. The absence of an intact IL-1 signal was associated with a higher susceptibility to develop meningitis. Furthermore, the lack of IL-1 impaired bacterial clearance, as reflected by an increased number of CFU in cerebrospinal fluid of IL-1R(-/-) mice. The characteristic pleocytosis of meningitis was not significantly altered in IL-1R(-/-) mice, but meningitis was associated with lower brain levels of cytokines. The mortality was significantly higher and earlier in the course of the disease in IL-1R(-/-) mice. These results demonstrate that endogenous IL-1 is required for an adequate host defense in pneumococcal meningitis.

[Central nervous tuberculosis in patients non-VIH: seven case reports]

PURPOSE

Tuberculosis involving the central nervous system (CNS) is rarely observed in non immuno-compromised hosts. We report herin the various clinical, biological and radiological manifestations observed in 7 patients with CNS tuberculosis.

METHODS

Clinical and biological records of 7 patients with CNS tuberculosis were retrospectively studied. All patients had encephalic CT-scan and MRI in the course of the disease.

RESULTS

5 women and 2 men with a mean age of 38.4 years initially initially presented with headache (n = 6), fever (n = 5), meningeal irritation (n = 3), localizing neurological signs (n = 1). Lumbar punction revealed lymphocytic meningitis (n = 6/7). Mycobacterium tuberculosis or bovis was isolated in 3 patients only. Cerebral tomodensitography or magnetic resonance imaging were initially normal in most of cases (n = 4/7), but discovered in the course of disease basilar meningitis (n = 6), hydrocephalus (n = 6), abcess or tuberculoma (n = 4). In all the patients, initiation of the treatment was complicated by clinical and/or biological deterioration, called paradoxal reaction, leading in all cases to glucocorticoid adjunction, with various final results. Indeed, 4 patients developed neurological sequelae. No patient died.

CONCLUSION

CNS tuberculosis is a rare disease in non immunocompromised patients whose diagnostic may be difficult due to the absence of specific clinical symptoms, negative initial radiological examination, as well as delayed and often negative bacterial isolation. Paradoxal reaction appeared to be frequent despite specific antibiotherapy and underlines the beneficial effects of addictive corticosteroids.

Brain cytokines and disease

Cytokines (e.g. various interleukins and subfamily members, tumor necrosis factors, interferons, chemokines and growth factors) act in the brain as immunoregulators and neuromodulators. Over a decade ago, the integrative article 'Immunoregulators in the Nervous System' (Neurosci Biobehav Rev 1991; 15: 185-215) provided a comprehensive framework of pivotal issues on cytokines and the nervous system that recently have been extensively studied. Cytokine profiles in the brain, including cytokine generation and action, have been studied in multiple models associated with neuropathophysiological conditions. These include: (1) acute conditions and disorders such as stroke (cerebral ischemia or infarction and intracranial hemorrhage), traumatic brain injury, spinal cord injury and acute neuropathies; (2) chronic neurodegenerative disorders and chronic conditions, including Alzheimer's disease, Parkinson's disease, neuropathic pain, epilepsy and chronic neuropathies; (3) brain infections, including bacterial meningitis and encephalitis; (4) brain tumors; (5) neuroimmunological disorders per se, such as multiple sclerosis; (5) psychiatric disorders, including schizophrenia and depression; (6) neurological and neuropsychiatric manifestations associated with non- central nervous system (CNS) disorders such as peripheral cancer, liver, kidney and metabolic compromise, and peripheral infectious and inflammatory conditions; and (7) cytokine immunotherapy, which can be accompanied by neuropsychiatric manifestations when administered either via peripheral or brain routes. Cytokine profiles have also been studied in multiple animal models challenged with inflammatory, infectious, chemical, malignant and stressor insults. Essentially data show that cytokines play a pivotal role in multiple neuropathophysiological processes associated with different types of disorders and insults. Cytokine expression and action in the brain shows a different profile across conditions, but some similarities exist. Under a defined temporal sequence, cytokine involvement in neuroprotection or the induction of a deleterious pathophysiological cascade and in resolution/healing is proposed depending on the type of cytokine. In the brain, functional interactions among cytokines, balance between pro-inflammatory and anti-inflammatory cytokines and functional interactions with neurotransmitters and neuropeptides play a pivotal role in the overall cytokine profile, pattern of neuropathophysiological cascades, and quality and magnitude of neuropsychiatric manifestations. In this brief review various selected cytokine-related issues with relevance to the brain are discussed.

Patterns of cytokines and soluble cellular receptors in the sera of children with acute chagas' disease

Cytokines and soluble cellular receptors are involved in inflammatory processes and probably in the pathogenesis of parasite and bacterial diseases. In a previous study, we reported increased levels of soluble receptors of interleukin-2 (sIL2-R) in children with acute Chagas' disease, one of the main parasitic infections that is endemic in Latin America. We sought to analyze the pattern of different cytokines and soluble receptors in the sera of children with chagasic infection. Children with acute and indeterminate stages of Chagas' disease, as well as nonchagasic children, were studied. Sera were assayed by enzyme-linked immunosorbent assay to measure the levels of tumor necrosis factor alpha (TNF-alpha), IL-6, IL-2, IL-8, IL-12, sIL-2R, and the soluble receptors of CD8 and CD4 (sCD8 and sCD4). sIL-2R and sCD8 showed the highest levels in serum in acutely infected children, decreasing after specific antiparasite therapy. Chronic children showed a pattern similar to the one of nonchagasic children. Although they were not statistically significant, TNF-alpha, IL-6, and sCD4 showed a tendency to reach high levels in the acutely infected group, whereas IL-2, IL-8, and IL-12 did not reveal changes with respect to the noninfected children. In summary, we report here the patterns of cytokines and soluble receptors in in the sera of children infected with Trypanosoma cruzi; we found significantly increased levels of sIL-2R and sCD8 in acute infection that decreased after therapy, and high levels of TNF-alpha, IL-6, and sCD4 in some of the acute patients. The measurement of sIL-2R and sCD8 may provide a useful tool in the follow-up of children with Chagas' disease.

The pathogenesis of febrile seizures: is there a role for specific infections?

Although fever is regarded as the main trigger in the pathogenesis of febrile seizures (FS), it is not supposed to be the unique causative factor. In FS, there is a strong familial predisposition. This does not exclude infections as a causative factor because subtle genetic polymorphisms have been demonstrated to affect the course of infections. We review the literature on: (1) the role of fever, especially the height of temperature, its cause, and metabolic effects induced by temperature; (2) the role of heredity; (3) the role of cytokines which play a role in the induction of fever; and (4) the role of type of infection, with emphasis on newly identified agents and improved diagnostic techniques. With modern molecular techniques such as PCR, viruses have been detected in the CSF far more often than previously thought, even in the absence of pleocytosis of the CSF. This makes it difficult to distinguish FS from acute encephalitis. FS may be caused by neuroinvasion or intracerebral activation of viruses. Further studies should focus on these options because therapeutic intervention is possible and may prevent late sequelae such as recurrent FS and subsequent epilepsy.

Persistent expression of cytokines in the chronic stage of CVB3-induced myocarditis in NMRI mice

Coxsackievirus B3 (CVB3)-induced myocarditis in NMRI mice represents a model for studying the pathogenesis of this chronic heart disease. Previously, we reported on specific cytokine patterns during the acute stage of myocarditis since cytokines are thought to play the important role in this cardiomyopathy. In this study, the expression of various cytokine mRNAs and CVB3-RNA kinetics was examined with particular emphasis on the late phase of myocarditis, by using reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization (ISH) and immunohistochemistry (IHC). In addition, replicating and persisting CVB3-RNAs were semiquantified by PCR-ELISA. Distinct histopathological changes responsible for ongoing heart disease were found and characterized by increased fibrosis, persistent cellular infiltration and degenerated necrotic myocytes. One of the most important findings of this study was that the mRNA-expression of TNF- alpha, IL-1 alpha, interferon- gamma, IL-10, IL-18, macrophage inflammatory protein-1 alpha (MIP-1 alpha), transforming growth factor- beta (TGF- beta) and inducible nitric oxide synthase (iNOS) persisted as long as 98 days after the virus infection. The induction of IL-10 as well as IFN- gamma mRNAs was also verified by ISH and IHC at days 28 and 98 p.i. The clearly apparent persistence of the viral genomes in the myocardium of infected mice was confirmed by seminested PCR, ISH, and PCR-enzyme linked immunoabsorbent assay (ELISA), showing the highest amount of viral RNA in myocardial cells at day 7 after infection. These data indicate that the persistence of viral RNA is associated with persistently high levels of cytokine mRNAs which, when translated, could severely contribute to pathological changes and injury of connective tissue in the chronic stage of myocarditis.

Neonatal bacterial meningitis

Despite major improvements in infant intensive care, neonatal meningitis remains a devastating disease. Survivors of bacterial meningitis are at high-risk for life-long neurological handicaps, and despite a reduction in mortality, the morbidity of neonatal meningitis has not changed substantially over the last thirty years. A substantial improvement in outcome is unlikely to result from further refinements in ICU technology or new antibiotics. However, recent advancements in our understanding of the pathogenesis of meningitis and the pathophysiology of brain injury in meningitis may provide the opportunity to interrupt the mechanisms that allow bacteria to enter the central nervous system and initiate the inflammatory response. Strategies aimed at modulating the inflammatory response must be chosen carefully, so as not to disrupt normal host responses needed for the infant to recover from the infectious episode.

Mononuclear cells and cytokines in the cerebrospinal fluid of echovirus 30 meningitis patients

The local immune response to echovirus 30 meningitis in children was investigated in 2 ways: using flow cytometry to examine the mononuclear cell and lymphocyte subsets and enzyme-linked immunosorbent assays to examine the cerebrospinal fluid (CSF) levels of cytokines, including monocyte chemoattractant protein-1 (MCP-1), interferon gamma (IFN-gamma) and interleukin-12 (IL-12). The numbers of macrophages in the CSF were increased, in particular during the early part of the acute stage. The levels of MCP-1, which is responsible for the accumulation of macrophages, as well as those of IFN-gamma and IL-12, which play important roles in the activation of macrophages and T helper (Th) 1 cells, respectively, were increased in the CSF of patients compared with the levels found in the controls. Likewise, numbers of activated CD4 + and CD8 + T lymphocytes were increased in the CSF. Since the ratio of CD4/CD8 correlated with the age of the patients, CD8 + T lymphocytes in the CSF might play a more important role in younger children.

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.

Value of cerebrospinal fluid leukocyte aggregation in distinguishing the causes of meningitis in children

BACKGROUND

Current laboratory tests often cannot distinguish between bacterial and aseptic meningitis rapidly and accurately. The ability to make a prompt diagnosis has important implications for the management and outcome of children with meningitis. The observation that leukocytes aggregate in the cerebrospinal fluid (CSF) has been previously reported, and it has been advocated as a reliable method to distinguish the causes of meningitis in children.

OBJECTIVE

To investigate the utility of CSF leukocyte aggregation as a screening test to distinguish between bacterial and aseptic meningitis.

METHODS

We compared the clinical and laboratory indices of 109 prospectively enrolled patients with meningitis (67 bacterial, 23 viral, 19 undefined etiology) and evaluated the validity of the CSF leukocyte aggregation test. The predefined leukocyte aggregation scores (LAS) were compared among the types of meningitis, and correlations with other markers of inflammation were calculated.

RESULTS

The median LAS was significantly higher (P < 0.001) in the bacterial (32.1%; range, 0 to 84.1%) than in the viral (0%; range, 0 to 16.6%) or undefined (0%; range, 0 to 20.7%) groups. The optimal sensitivity of the leukocyte aggregation test, 98.5 to 92.5%, was demonstrated with LAS values of 0 to 3%. The corresponding specificity was 64.3 to 88.1%. The peripheral white blood cell (WBC) count, serum C-reactive protein, CSF WBC count, blood culture, CSF Gram stain and CSF culture were inferior to the LAS as screening tests when compared individually. The LAS was as effective as CSF protein, TNF-alpha, IL-1-beta, IL-6 and IL-8 to predict bacterial meningitis. In a logistic regression model that included routine laboratory tests, the best predictor of bacterial meningitis was the LAS (odds ratio, 1.6 to 3.7). Significant correlations were demonstrated between the LAS and CSF protein, CSF WBC count, IL-1-beta, IL-6 and IL-8. Duration of symptoms before diagnosis, pretreatment with antibiotics, HIV-1 infection status and CSF red blood cell count did not significantly alter the LAS.

CONCLUSIONS

There is no single test to diagnose the etiology of meningitis in children promptly and accurately. The finding of leukocyte aggregation in CSF might be of value as a sensitive adjunctive screening tool for the timely diagnosis of bacterial meningitis, recognizing that it has low specificity and potential practical limitations.

Cerebrospinal fluid tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-8 as diagnostic markers of cerebrospinal fluid infection in neurosurgical patients

OBJECTIVE

To evaluate whether cerebrospinal fluid concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, or IL-8 may be used as diagnostic markers for the differential diagnosis of aseptic vs. bacterial meningitis and/or ventriculitis in neurosurgical patients.

DESIGN

Prospective, observational study.

SETTING

University teaching hospital.

SUBJECTS

A total of 112 cerebrospinal fluid samples from 14 asymptomatic patients with normal cerebrospinal fluid after neurosurgery, 27 asymptomatic and 19 symptomatic patients with postneurosurgical aseptic meningitis, 32 patients with postneurosurgical cerebrospinal fluid infection, and 20 with severe subarachnoid and/or cerebral hemorrhage.

MEASUREMENTS AND MAIN RESULTS

Specific ELISA kits were used to analyze TNF-alpha, IL-1beta, IL-6, and IL-8 concentrations on cerebrospinal fluid samples. Elevations in cerebrospinal fluid concentrations of TNF-alpha, IL-1beta, IL-6, and IL-8 were induced by different diseases or neurosurgical procedures, but cerebrospinal fluid bacterial infection induced the highest concentrations. To discriminate between aseptic cerebrospinal fluid pleocytosis and cerebrospinal fluid infection with a specificity of 95%, cerebrospinal fluid leukocyte count >1700/mL, TNF-alpha >150 pg/mL, and IL-1beta >90 pg/mL showed sensitivities of 51%, 74%, and 90%, respectively. Sufficiently sensitive and specific cutoff points could not be found for cerebrospinal fluid IL-6 or IL-8.

CONCLUSION

Cerebrospinal fluid IL-1beta appears to be the best biochemical marker of cerebrospinal fluid infection in neurosurgical patients.

Inhibition of Escherichia coli-induced meningitis by carboxyfullerence

The effect of a water-soluble malonic acid derivative of carboxyfullerence (C60) against Escherichia coli-induced meningitis was tested. C60 can protect the mice from E. coli-induced death in a dose-dependent manner. C60 administered intraperitoneally as late as 9 h after E. coli injection was still protective. The C60-treated mice had less tumor necrosis factor alpha and interleukin-1beta production by staining of brain tissue compared to the levels of production for nontreated mice. The E. coli-induced increases in blood-brain barrier permeability and inflammatory neutrophilic infiltration were also inhibited. These data suggest that C60 is a potentially therapeutic agent for bacterial meningitis.

Detection of influenza virus RNA by reverse transcription-PCR and proinflammatory cytokines in influenza-virus-associated encephalopathy

Eleven children with acute encephalopathy associated with an influenza virus infection were treated during the 1997-1998 influenza season. Reverse transcription-polymerase chain reaction (RT-PCR) assay was used to detect the viral genome in peripheral blood and cerebrospinal fluid (CSF) samples. The results were compared with those of control influenza patients without neurological complications. Viral RNA was detected only in the peripheral blood mononuclear cells of one patient with influenza-virus-associated encephalopathy (1 of 9; 11%) and in the CSF of another patient (1 of 11;9%). RT-PCR was negative in the blood of all the controls, but the percentage of RT-PCR-positive samples in the two groups was not significantly different. Cytokines and soluble cytokine receptors in plasma and CSF were then quantified using an enzyme-linked immunosorbent assay. The CSF concentrations of soluble tumor necrosis factor receptor-1 were elevated in two patients and interleukin-6 (IL-6) was elevated in one patient with influenza-virus-associated encephalopathy. On the other hand, the plasma concentrations of IL-6 were elevated in four of nine patients. The number of encephalopathy patients who had elevated plasma concentrations of IL-6 100 pg/ml was significantly higher than that of controls (P= .01). In conclusion, the infrequent detection of the viral genome in the CSF and blood showed that direct invasion of the virus into the central nervous system was an uncommon event. Proinflammatory cytokines and soluble cytokine receptors may mediate the disease. The high plasma concentration of IL-6 could be an indicator of the progression to encephalopathy.

Beta-2-microglobulin and ferritin in cerebrospinal fluid for evaluation of patients with meningitis of different etiologies

To determine whether or not the beta-2-microglobulin (beta2-m) and/or ferritin levels in cerebrospinal fluid (CSF) can be used as markers for the differential diagnosis of meningitis and determination of the response to treatment, 122 subjects with etiologically well-characterized diagnoses were classified into three groups: bacterial meningitis (n = 5; mean age +/- SD. 1.0+/-1.0 year), viral meningitis (n = 39; 5.9+/-3.8 years), and a non-meningitis group (n = 78; 5.2+/-4.9 years). The levels of beta2-m and ferritin in CSF were determined by means of a latex photometric immunoassay. The statistical significance of the data was analyzed with the Mann Whitney U-test. A receiver operating characteristic curve was used to evaluate the diagnostic accuracy of each prediction marker. This study indicated that (1) the levels of beta2-m and ferritin in CSF were related with age in the non-meningitis group: subjects of up to 5 months of age exhibited higher concentrations of these proteins than ones of above 6 months of age (beta2-m, 1.89+/-1.13 vs. 0.84+/-0.65 mg/l. P < 0.01; ferritin, 2.97+/-2.04 vs. 1.81+/-1.34 microg/l, P = 0.09); (2) the beta2-m level was significantly higher in the CSF of patients with viral meningitis than in ones without meningitis (2.41+/-1.23 vs. 0.84+/-0.65 mg/l, P < 0.01): the best cut-off value was 1.2 mg/l (3) the ferritin level was significantly higher in the CSF of patients with bacterial meningitis than in ones with viral meningitis (43.24+/-39.49 vs. 6.81+/-7.41 microg/l, P < (.01): the best cut-off value was 7.5 microg/l; and (4) sequential measurement of the CSF ferritin level was of value for determination of the response to antibiotic treatment for bacterial meningitis. These results only apply to patients of greater than 6 months of age. beta2-m and ferritin in the CSF can be used as an ancillary tool for diagnostic guidance in the acute phase of meningitis and determination of the response to treatment for bacterial meningitis.

Interleukin-1beta-induced fever in young and old Long-Evans rats

Aging is associated with a blunted or absent fever response to naturally occurring infections or to the peripheral administration of bacterial products and proinflammatory cytokines, including interleukin-1beta (IL-1beta). Whether old rats also exhibit an attenuated fever response when challenged with direct brain administration of IL-1beta is unknown. Here we investigated the fever response of young (3-5 mo) and old (24-26 mo) Long-Evans rats to the intracerebroventricular microinfusion of IL-1beta. Core body temperature was monitored by telemetry in freely moving rats. Intracerebroventricularly administered IL-1beta induced comparable increases in body temperature in young and old Long-Evans rats. In the two groups, IL-1beta-induced fever was similar both in latency to peak fever and maximal fever response, whether the cytokine was administered 2 h after lights on or just before lights off. These data show that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of IL-1beta.

Cytokine-induced fever in obese (fa/fa) and lean (Fa/Fa) Zucker rats

In earlier work, we reported that genetically obese (fa/fa) Zucker rats exhibited significantly greater anorexia than did lean (Fa/Fa) Zucker rats to intracerebroventricular infusion of interleukin (IL)-1beta. Here, we investigated the fever response of obese (fa/fa) and lean (Fa/Fa) Zucker rats to intracerebroventricular microinfusion of IL-1beta as well as to the following other cytokines: IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha). Core body temperature was monitored by a radiotelemetry system in freely moving rats. The results show that 1) both IL-1beta and IL-6 induce fevers in obese and lean rats; 2) IL-1beta induces a significantly higher fever response in obese rats than it does in lean rats; 3) IL-6 induces a significantly higher fever response in lean rats than it does in obese rats; 4) IL-2 induces a moderate fever response in lean but not obese rats; 5) TNF-alpha induces a similar fever response in obese and lean rats; and 6) the fevers induced by each effective cytokine have different time courses. Thus obese (fa/fa) and lean (Fa/Fa) Zucker rats show differential responsiveness to the intracerebroventricular microinfusion of various classes of cytokines. This suggests that genetic obesity in the fa/fa Zucker rat is associated with differential cytokine action on thermoregulatory mechanisms.

In vivo IL-1beta-induced modulation of G-protein alphaO subunit subclass in the hypothalamic ventromedial nucleus: implications to IL-1beta-associated anorexia

The intracerebroventricular (i.c.v.) administration of interleukin-1beta (IL-1beta) induces anorexia in rats at doses that yield estimated pathophysiological concentrations in the cerebrospinal fluid. IL-1beta also induces anorexia when administered into the hypothalamic ventromedial nucleus (VMN), an important brain site for the control of feeding. A variety of guanine nucleotide binding protein (G-protein) coupled receptors (e. g., for neurotransmitters and neuropeptides) participate in the integrative regulation of feeding. Our previous studies reported that the VMN G-protein alphaO common subunit subclass is involved in the control of normal feeding, and that IL-1beta modulates calcium channel currents via a pertussis toxin (PTX)-sensitive G-protein (GalphaO/Galphai). Here, we examined the profile of GalphaO protein expression in the hypothalamic VMN during IL-1beta-induced anorexia. Intracerebroventricular microinfusion of IL-1beta (0.5 to 8.0 ng/24 h for 72 h) into the third cerebral ventricle dose-dependently induced anorexia (p<0.001) and decreased the VMN GalphaO common protein levels (p<0.001). Heat-inactivated IL-1beta and IL-1beta plus IL-1 receptor antagonist (a competitive inhibitor of IL-1beta action) had no effect on food intake or on VMN GalphaO common protein content. RT-PCR analysis of VMN RNA from IL-1beta-treated rats generated an expression profile for GalphaO common subunit; however, no modulation at the mRNA level was observed. The results suggest that anorexia induced by the central administration of IL-1beta involves modification of G-protein alphaO common subunit profile in the central nervous system.

Chemokines and chemotaxis of leukocytes in infectious meningitis

Chemokines constitute a constantly growing family of small inflammatory cytokines. They have been implied in many different diseases of the CNS including trauma, stroke and inflammation, e.g., multiple sclerosis. In this review we focus on the role of chemokines in infectious meningitis of bacterial or viral origin. In experimental bacterial meningitis induced by Listeria monocytogeneses both CXC and CC chemokines namely MIP-1alpha, MIP-1beta and MIP-2 are produced intrathecally by meningeal macrophages and leukocytes which infiltrate into the CNS. In patients with bacterial meningitis, IL-8, GROalpha, MCP-1, MIP-1alpha and MIP-1beta are detectable in the CSF. These chemokines contribute to CSF mediated chemotaxis on neutrophils and PBMC in vitro. In viral meningitis IL-8, IP-10 and MCP-1 are identified in the CSF to be responsible for chemotactic activity on neutrophils, PBMC and activated T cells. Taken collectively these data indicate that the recruitment of leukocytes in infectious meningitis involves the intrathecal production of chemokines.

Interleukin-1beta system (ligand, receptor type I, receptor accessory protein and receptor antagonist), TNF-alpha, TGF-beta1 and neuropeptide Y mRNAs in specific brain regions during bacterial LPS-induced anorexia

Bacterial lipopolysaccharide (LPS) or endotoxin induces neurological manifestations including anorexia. It is proposed that LPS-induced cytokine production is involved in the generation of neurological manifestations and in neuroinflammatory/immunological responses during gram-negative infections. For example, LPS-induced effects can be blocked or ameliorated by the interleukin-1 receptor antagonist (IL-1Ra). Here, sensitive and specific RNase protection assays were used to investigate the effects of the intracerebroventricular (i.c.v.) administration of LPS on mRNA levels of interleukin-1beta (IL-1beta) system components, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, and neuropeptide Y (NPY) in the cerebellum, hippocampus, and hypothalamus. The same brain region sample was analyzed with all of the antisense probes. The data show simultaneous local induction of multiple cytokine components messenger ribonucleic acids (mRNAs) within specific brain regions in anorectic rats responding to i.c.v. administered LPS (500 ng/rat). Interleukin-1beta and IL-1Ra had a similar mRNA induction profile (hypothalamus > cerebellum > hippocampus). Interleukin-1 receptor type I (IL-1RI) mRNA also increased in all three brain regions examined, and the soluble form of IL-1 receptor accessory protein (IL-1R AcP II) mRNA was induced in the hypothalamus. Tumor necrosis factor-alpha mRNA levels increased in the hypothalamus > hippocampus > cerebellum. Levels of membrane bound IL-1R AcP, TGF-beta1, and NPY mRNAs did not change significantly in any brain region. The results suggest that: (1) endogenous up-regulation of IL-1beta and TNF-alpha in the hypothalamus contribute to LPS-induced anorexia; and (2) the ratio IL-1Ra/IL-1beta, and IL-1beta <--> TNF-alpha interactions may have implications for gram-negative infections associated with high levels of LPS in the brain-cerebrospinal fluid.

Interleukin-1beta (IL-1beta)-induced modulation of the hypothalamic IL-1beta system, tumor necrosis factor-alpha, and transforming growth factor-beta1 mRNAs in obese (fa/fa) and lean (Fa/Fa) Zucker rats: implications to IL-1beta feedback systems and cytokine-cytokine interactions

Interleukin-1beta (IL-1beta) induces anorexia, fever, sleep changes, and neuroendocrine alterations when administered into the brain. Here, we investigated the regulation of the IL-1beta system (ligand, receptors, receptor accessory protein, and receptor antagonist), tumor necrosis factor-alpoha (TNF-alpha), transforming growth factor (TGF)-beta1, and TGF-alpha mRNAs in the hypothalamus of obese (fa/fa) and lean (Fa/Fa) Zucker rats in response to the intracerebroventricular microinfusion of IL-1beta (8.0 ng/24 hr for 72 hr, a dose that yields estimated pathophysiological concentrations in the cerebrospinal fluid). IL-1beta increased IL-1beta, IL-1 receptor types I and II (IL-1RI and IL-1RII), IL-1 receptor accessory protein soluble form (IL-1R AcP II), IL-1 receptor antagonist (IL-1Ra), TNF-alpha, and TGF-beta1 mRNAs in the hypothalamus from obese and lean rats. IL-1beta-induced IL-1beta system and ligand (IL-1beta, TNF-alpha, and TGF-beta1) mRNA profiles were highly intercorrelated in the same samples. Levels of membrane-bound IL-1R AcP and TGF-alpha mRNAs did not change. Heat-inactivated IL-1beta had no effect. The data suggest 1) the operation of an IL-1beta feedback system (IL-1beta/IL-1RI/IL-1R Acp II/IL-1RII/IL-1Ra) and 2) potential cytokine-cytokine interactions with positive (IL-1beta <--> TNF-alpha) and negative (TGF-beta1 --> IL-1beta/TNF-alpha) feedback. Dysregulation of the IL-1beta feedback system and the TGF-beta1/IL-1beta-TNF-alpha balance may have implications for neurological disorders associated with high levels of IL-1beta in the brain.

Distribution of tumor necrosis factor receptor messenger RNA in normal and herpes simplex virus infected trigeminal ganglia in the mouse

PURPOSE

to investigate the distribution of p55 and p75 tumor necrosis factor (TNF) receptor mRNA in normal murine trigeminal ganglia, and in murine trigeminal ganglia acutely infected with McKrae strain herpes simplex virus (HSV).

METHODS

in situ hybridization with antisense 35S-labeled riboprobes for mRNA encoding both the p55 and p75 TNF receptor (TNFR) subtypes was used in normal and HSV-infected murine trigeminal ganglia. Sense riboprobes were used as controls.

RESULTS

in situ hybridization with both p55 and p75 riboprobes produced a strong autoradiographic signal over many, but not all, trigeminal sensory neurons. Signal for mRNA encoding both TNFR subtypes was also present over the arachnoid layers surrounding trigeminal ganglia. Acute ocular HSV infection was accompanied by an intense leukocytic infiltrate into the ophthalmic portion of the trigeminal ganglia, and, in this setting, increased p55 and p75 mRNA signal was closely related to the location and number of infiltrating white blood cells. The distribution and number of trigeminal sensory neurons expressing mRNA for the two TNFR subtypes did not appear to change following infection. Signal over control sections hybridized with sense p55 and p75 TNFR cRNA probes was comparable to background.

CONCLUSIONS

the observed distribution of p55 and p75 TNFR mRNA over trigeminal sensory neurons and over the arachnoid layers surrounding trigeminal ganglia supports suggestions that TNF has a direct effect on neurons, either as a neuromodulator or neurotrophic factor, and that TNF may play a central role in blood-brain barrier regulation. Increased signal for TNFR mRNA in acutely infected trigeminal ganglia appears to reflect infiltration by receptor-bearing white blood cells.

Functional relationships between sensory nerve fibers and mast cells of dura mater in normal and inflammatory conditions

In this study, we have characterized the phenotype of mast cells in rat dura mater and their topological and functional relationships with C-fibers in normal and inflammatory conditions. Three mast cell populations with different size, morphology and localization were characterized by their content of specific neutral serine proteases. They showed immunoreactivity corresponding to rat mast cell protease I, rat mast cell protease II, or both proteases. Using confocal microscopy, all three mast cell types were observed in close apposition (distance less than 100 nm) to calcitonin gene-related peptide- and substance P-immunoreactive nerve fibers in both controls and rats infected with the nematode Nippostrongylus brasiliensis. After nematode infection or neonatal treatment with capsaicin, a large increase in the number of rat mast cell protease II-immunoreactive mast cells was found within dura mater segments (+1478% and +596%, respectively), without concomitant changes of rat mast cell protease I- or rat mast cell protease I/II-immunoreactive mast cells. Under both these conditions, the increase in mast cell number was accompanied by a significant increase in rat mast cell protease II level within tissue extracts (+281% after nematode infection and +36% after capsaicin treatment). The functional interaction of mast cells with sensory nerve fibers in the dura mater was assessed by evaluating [3H]histamine synthesis after administration of L-[3H]histidine, an index of mast cell activity. The H3 receptor agonist (R)-alpha-methylhistamine (15 mg/kg, i.p.) had no effect, but administration of the H3 receptor antagonist, thioperamide (10 mg/kg, i.p.), resulted in a significant increase of [3H]histamine synthesis (+62%). This effect was reduced in neonatal capsaicin-treated rats, but not completely suppressed (+35%), very likely because of partial denervation, as assessed by monitoring calcitonin gene-related peptide immunoreactivity. It is concluded that, in the dura mater, as in peripheral tissues, sensory nerve fibers and mast cells actively synthesizing and releasing histamine form a short inhibitory feedback loop involving prejunctional H3 receptors that could regulate the release of pro-inflammatory mediators, thus limiting the extent of inflammatory reactions.

Cerebrospinal fluid analysis in clinical diagnosis

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Interleukin 6 in cerebrospinal fluid of patients with meningitis is not a useful diagnostic marker in the differential diagnosis of meningitis

We assayed interleukin 6 (IL-6) concentrations in cerebrospinal fluid (CSF) from patients affected by meningitis of different aetiologies, and verified whether IL-6 can be used as a diagnostic marker in the differential diagnosis of meningitis. We used a monoclonal antibody enzyme immunoassay to test 98 CSF samples classified as pyogenic (15), viral (15), self-resolving aseptic meningitis (20), other infectious meningitis (9), neoplastic (4) and normal CSF from patients with (20) and without (15) non-infectious neurological diseases. CSF IL-6 concentrations were increased in pyogenic meningitis (100%) and in more than 50% of viral and other subarachnoid space infections, and rarely in patients without central nervous system infections. Though patients affected by pyogenic meningitis showed the highest levels of CSF IL-6, only a cut-off point > or = 10000 pg/mL was able to discriminate pyogenic meningitis from those of other aetiologies with a specificity > or = 94% and a positive predictive value of > or = 0.75 but the sensitivity was < or = 60%. Therefore, CSF IL-6 concentration is not a good diagnostic marker in the differential diagnosis of meningitis.

Is TNF-alpha a prognostic factor in patients with sepsis?

OBJECTIVE: To determine tumor necrosis factor-alpha (TNF-alpha) levels in a prospective study in 58 hospitalized patients in a department of internal medicine (63 episodes, 29 in immunocompromised patients) during a 7-month period. METHODS: Patients fulfilling the following criteria were included: clinical evidence of acute infection, temperature >38.2 degrees C, tachycardia >90 beats/min, tachypnea >20 breaths/min. Samples were taken from day 1 up to day 13 after an infection was diagnosed, and TNF-alpha was determined by enzyme immunoassay. RESULTS: In 29 episodes (46.0%) the infection was microbiologically documented. The median of the TNF-alpha levels in the Gram-negative episodes was significantly higher than that in the Gram-positive episodes (p=0.002). Thirteen of 63 episodes (20.6%) had a fatal outcome. With respect to all measured values, the non-survivors had a significantly higher median of TNF-alpha levels than the survivors (p=0.0001). There was, however, great interpatient and intrapatient variability in TNF-alpha levels; thus, no unequivocal correlation between TNF-alpha and outcome could be documented. CONCLUSIONS: Our data indicate that the influence of the infecting organism on TNF-alpha kinetics is less pronounced than that of the underlying disease.

Differential responsiveness of obese (fa/fa) and lean (Fa/Fa) Zucker rats to cytokine-induced anorexia

Pathophysiological and pharmacological concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in the cerebrospinal fluid (CSF) induce anorexia in normal rats. Obesity in humans and rodents is associated with increased TNF-alpha messenger RNA and protein levels in various cell types. This suggests that obese individuals may have differential regulation of cytokine production and dissimilar responsiveness to cytokines. In the present study, we investigated the effects of the intracerebroventricular (ICV) microinfusion of TNF-alpha (50, 100, and 500 ng/rat), IL-1 beta (1.0, 4.0, and 8.0 ng), and TNF-alpha (100 ng) plus IL-1 beta (1.0 ng) on obese (fa/fa) and lean (Fa/Fa) Zucker rats. The results show that: TNF-alpha and IL-1 beta, and the concomitant administration of TNF-alpha and IL-1 beta decreased the short-term (4 hours), nighttime (12 hours), and total daily food intakes in obese and lean rats; IL-1 beta was more potent relative to TNF-alpha; obese rats showed greater responsiveness to IL-1 beta: 8.0 ng IL-1 beta, for example, decreased the 12-hour food intake by 52% in obese and 22% in lean rats. On the other hand, obese and lean rats did not exhibit a significantly different responsiveness to the anorexia induced by 50, 100, or 500 ng TNF-alpha at the 4-hour period; and the concomitant ICV administration of TNF-alpha and IL-1 beta induced anorexia with additive (4-hour period) or synergistic (12-hour and 24-hour periods) effects in obese rats. The effect of TNF-alpha plus IL-1 beta in lean rats was greater than additive for the 12-hour and 24-hour periods. The difference in suppression of total daily food intake by TNF-alpha plus IL-1 beta in obese (-43%) versus lean (-23%) rats was significantly different (p < 0.01). The results show that obese (fa/fa) and lean (Fa/Fa) Zucker rats have differential responsiveness to the ICV microinfusion of two different classes of cytokines.

Molecular regulation of the brain interleukin-1 beta system in obese (fa/fa) and lean (Fa/Fa) Zucker rats

Interleukin-1 beta (IL-1 beta) induces anorexia when administered acutely or chronically into the cerebrospinal fluid (CSF) at doses that yield estimated pathophysiological concentrations. Enhanced sensitivity to IL-1 beta-induced anorexia has been observed in animal models of obesity, including the obese (fa/fa) Zucker rat. Obesity is also associated with increased tumor necrosis factor-alpha mRNA expression in adipose tissue. This suggests that obese individuals may have dissimilar sensitivity to cytokine action and differential regulation of cytokine production. In this study, we investigated the regulation of the IL-1 beta system (IL-1 beta, IL-1 receptor type I (IL-1RI) and IL-1 receptor antagonist (IL-1Ra)) in the central nervous system (CNS) in response to the chronic intracerebroventricular (i.c.v.) microinfusion (via osmotic minipumps) of 8 ng IL-1 beta/24 h/72 h-a dose that yields estimated pathophysiological concentrations in the CSF. IL-1 beta, IL-1RI and IL-1Ra mRNAs were determined by sensitive RNase protection assays in brain target regions for IL-1 beta (cerebellum, parieto-frontal cortex, hippocampus, hypothalamus and midbrain). The results show that chronic i.c.v. microinfusion of IL-1 beta increased the IL-1 beta mRNA, IL-1R1 mRNA and IL-1Ra mRNA levels in the hypothalamus > cerebellum in both obese (fa/fa) and lean (Fa/Fa) Zucker rats. IL-1 beta mRNA levels also increased in the cortex, hippocampus and midbrain of obese (fa/fa) rats. The profiles of IL-1 beta mRNA, IL-1RI mRNA and IL-1Ra mRNA in the same hypothalamic samples obtained from obese or lean rats were highly intercorrelated. However, no significant differences in the level of IL-1 beta system mRNAs induction were observed in any brain region between obese and lean rats. On the other hand, levels of rat glyceraldehyde 3-phosphate dehydrogenase mRNA were fairly constant, and heat-inactivated IL-1 beta (8 ng/24 h/72 h) had no effect on IL-1 beta, IL-1RI and IL-1Ra mRNAs levels in any brain region. The data suggest: (1) the operation of an IL-1 beta feedback system (IL-1 beta/IL-1Ra/IL-1RI) in brain regions; (2) that enhanced sensitivity of obese rats to IL-1 beta-induced anorexia is not dependent on changes in the brain IL-1 beta system at the mRNA level; and (3) that the present novel approach can be used to investigate the molecular basis of cytokine action in the CNS.

Tumor necrosis factor-alpha, lymphotoxin, interleukin (IL)-6, IL-10, IL-12 and perforin mRNA expression in mononuclear cells in response to acetylcholine receptor is augmented in myasthenia gravis

Myasthenia gravis (MG) is a neuromuscular disorder mediated by autoantibodies against the nicotinic acetylcholine receptor (AChR) on the postsynaptic membrane of the neuromuscular junction. The production of antibodies is regulated by T cells by means of immunoregulatory cytokines. To investigate the involvement of TNF-alpha, lymphotoxin (LT), IL-6, IL-10, IL-12 and perforin in MG, numbers of cytokine mRNA expressing blood mononuclear cells (MNC) were examined in patients with MG and controls. LT belongs to the Th1 cell related cytokines, IL-6 and IL-10 to the Th2 type, TNF-alpha is produced by both Th1 and Th2 cells, IL-12 induces T cell switch towards the Th1 type and perforin is an effector molecule inducing cell lysis. Short term culture of MNC with AChR revealed augmented levels of AChR-reactive TNF-alpha, LT, IL-6, IL-10, IL-12 and perforin mRNA expressing cells in MG compared to levels obtained without AChR or in presence of control antigen. AChR-reactive TNF-alpha, IL-6, IL-10, IL-12 and perforin mRNA expressing cells were higher in MG than controls. These findings suggest that the cytokines TNF-alpha, LT, IL-6, IL-10 and IL-12, and the cytolytic effector molecule perforin are also involved in MG.

Regulation of brain interleukin-1 beta (IL-1 beta) system mRNAs in response to pathophysiological concentrations of IL-1 beta in the cerebrospinal fluid

Interleukin-1 beta (IL-1 beta) is released during pathophysiological processes. IL-1 beta induces neurological manifestations when administered into the cerebrospinal fluid (CSF) at pathophysiological concentrations detected during central nervous system (CNS) infections and other neurological disorders. In the present study, we investigated the regulation of the IL-1 beta system in the CNS in response to the chronic intracerebroventricular (icv) microinfusion of IL-1 beta at estimated pathophysiological concentrations in the CSF. IL-1 receptor type I (IL-1RI), IL-1 receptor antagonist (IL-1Ra), and IL-1 beta mRNAs were determined by sensitive RNase protection assays in brain target regions for IL-1 beta (cerebellum, parieto-frontal cortex, hippocampus, and midbrain). The results show that chronic icy microinfusion of IL-1 beta induced significant anorexia, increased the cerebellar IL-1RI mRNA content, increased IL-1Ra and IL-1 beta mRNAs levels in the cerebellum > midbrain > cortex > hippocampus, and induced profiles of IL-1RI mRNA, IL-1Ra mRNA, and IL-1 beta mRNA that were highly intercorrelated. On the other hand, levels of rat glyceraldehyde 3-phosphate dehydrogenase mRNA and 18S rRNA were fairly constant, and heat-inactivated IL-1 beta had no effect on food intake or on IL-1RI, IL-1Ra, and IL-1 beta mRNAs levels in any brain region. The data suggest the operation of an IL-1 beta feedback system (IL-1 beta/ IL-1Ra/IL-1RI) in brain regions. Dysregulation of the CNS IL-1 beta feedback system may have pathophysiological significance. This may be reflected, for example, in the pathogenicity and severity of neurological diseases, such as CNS infections.

Interleukin-8 in cerebrospinal fluid from patients with septic and aseptic meningitis

Using a monoclonal antibody enzyme immunoassay, the concentration of interleukin-8 (IL-8) in cerebrospinal fluid (CSF) from 52 patients suspected of having meningitis was studied. The CSF IL-8 concentration was significantly higher in septic meningitis of known and unknown etiology than in aseptic meningitis and significantly higher in aseptic meningitis than in patients without meningitis. The CSF levels of IL-8 correlated with the levels of tumor necrosis factor-alpha, leukocyte count, neutrophil count, protein level, CSF/blood glucose ratio, and the number of days patients were hospitalized. The IL-8 values used to distinguish septic from aseptic meningitis, at a cut-off point of 3.00 micrograms/l, showed a sensitivity of 81%, a specificity of 92%, and a positive predictive value of 96%. The results suggest that determining IL-8 levels may be useful in the differential diagnosis of meningitis.