Predictive value of cerebrospinal fluid matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 concentrations in childhood bacterial meningitis

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.

High Concentration of Protein Oxidation Biomarker O-Tyr/Phe Predicts Better Outcome in Childhood Bacterial Meningitis

Neuronal damage in bacterial meningitis (BM) partly stems from the host´s inflammatory response and induced oxidative stress (OS). We studied the association of cerebrospinal fluid (CSF) biomarkers indicating oxidative damage to proteins with course of illness and outcome in childhood BM in Angola. Ortho-tyrosine/phenylalanine (o-Tyr/Phe), 3-chlorotyrosine/para-tyrosine (3Cl-Tyr/p-Tyr), and 3-nitrotyrosine/para-tyrosine (3NO2-Tyr/p-Tyr) concentration ratios were measured in 79 BM admission CSF samples, employing liquid chromatography coupled to tandem mass spectrometry. Besides death, disease outcomes were registered on Day 7 of treatment and one month after discharge (control visit). The outcome was graded according to the modified Glasgow Outcome Scale (GOS), which considers neurological and audiological sequelae. Children with a o-Tyr/Phe ratio below the median were more likely to present focal convulsions and secondary fever during recovery and suboptimal outcome (GOS < 5) on Day 7 and at control visit (odds ratio (OR) 2.85; 95% CI 1.14–7.14 and OR 5.23; 95% CI 1.66–16.52, respectively). Their most common sequela was ataxia on Day 7 and at control visit (OR 8.55; 95% CI 2.27–32.22 and OR 5.83; 95% CI 1.12–30.4, respectively). The association of a higher admission CSF o-Tyr/Phe ratio with a better course and outcome for pediatric BM points to a beneficial effect of OS.

Comparison of urine proteome among rat models by intraperitoneal injection with single bacteria and co-injection with two bacteria

PURPOSE

To explore and compare urine proteome changes among rat models by intraperitoneal injection with single bacteria and co-injection with two bacteria.

METHOD

Escherichia coli and Staphylococcus aureus are two common human pathogens. Three rat models were established: (i) the intraperitoneal co-injection of E. coli and S. aureus model (ES model), (ii) intraperitoneal injection of E. coli model (E model), and (iii) intraperitoneal injection of S. aureus model (S model). Urinary proteomes on days 0, 1 and 2 of the three models were analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).

RESULTS

A total of 111, 34 and 94 differential proteins were identified in the ES model, E model and S model, respectively. Among them, some differential proteins were reported to be associated with bacterial infection. Approximately 47% differential proteins in the E model overlapped with ES model, and 37% differential proteins in the S model overlapped with ES model. Compared with the E model and S model, a total of 71 unique differential proteins were identified in the ES model.

CONCLUSION

Our results indicated that (1) the urine proteome could distinguish different bacterial intraperitoneal injections models and (2) the effects of co-injection with two bacteria on the urine proteome were not simple superposition of single injection.

CSF Levels of Elongation Factor Tu Is Associated With Increased Mortality in Malawian Adults With Streptococcus pneumoniae Meningitis

Background

Mortality from bacterial meningitis, predominately caused by Streptococcus pneumoniae, exceeds 50% in sub-Saharan African countries with high HIV prevalence. Underlying causes of high mortality are poorly understood. We examined the host and pathogen proteome in the CSF of adults with proven pneumococcal meningitis (PM), testing if there was an association between differentially expressed proteins and outcome.

Materials/Methods

CSF proteomes were analyzed by quantitative Mass-Spectrometry. Spectra were identified using the Swissprot human and TIGR4 pneumococcal protein libraries. Proteins were quantitated and analyzed against mortality. Unique proteins in PM were identified against published normal CSF proteome. Random-Forest models were used to test for protein signatures discriminating outcome. Proteins of interest were tested for their effects on growth and neutrophil opsonophagocytic killing of S. pneumoniae.

Results

CSF proteomes were available for 57 Adults with PM (median age 32 years, 60% male, 70% HIV-1 co-infected, mortality 63%). Three hundred sixty individual human and 23 pneumococcal proteins were identified. Of the human protein hits, 30% were not expressed in normal CSF, and these were strongly associated with inflammation and primarily related to neutrophil activity. No human protein signature predicted outcome. However, expression of the essential S. pneumoniae protein Elongation Factor Tu (EF-Tu) was significantly increased in CSF of non-survivors [False Discovery Rate (q) <0.001]. Expression of EF-Tu was negatively co-correlated against expression of Neutrophil defensin (r 0.4 p p < 0.002), but not against complement proteins C3 or Factor H. In vitro, addition of EF-Tu protein impaired S. pneumoniae neutrophil killing in CSF.

Conclusions

Excessive S. pneumoniae EF-Tu protein in CSF was associated with reduced survival in meningitis in a high HIV prevalence population. We show EF-Tu may inhibit neutrophil mediated killing of S. pneumoniae in CSF. Further mechanistic work is required to better understand how S. pneumoniae avoids essential innate immune responses during PM through production of excess EF-Tu.

Combined therapy with ceftriaxone and doxycycline does not improve the outcome of meningococcal meningitis in mice compared to ceftriaxone monotherapy

BACKGROUND

Meningococcal meningitis (MM) is a life-threatening disease associated with approximately 10% case fatality rates and neurological sequelae in 10-20% of the cases. Recently, we have shown that the matrix metalloproteinase (MMP) inhibitor BB-94 reduced brain injury in a mouse model of MM. The present study aimed to assess whether doxycycline (DOX), a tetracycline that showed a neuroprotective effect as adjuvant therapy in experimental pneumococcal meningitis (PM), would also exert a beneficial effect when given as adjunctive therapy to ceftriaxone (CRO) in experimental MM.

METHODS

BALB/c mice were infected by the intracisternal route with a group C Neisseria meningitidis strain. Eighteen h post infection (hpi), animals were randomised for treatment with CRO [100 mg/kg subcutaneously (s.c.)], CRO plus DOX (30 mg/kg s.c.) or saline (control s.c.). Antibiotic treatment was repeated 24 and 40 hpi. Mouse survival and clinical signs, bacterial counts in cerebella, brain damage, MMP-9 and cyto/chemokine levels were assessed 48 hpi.

RESULTS

Analysis of bacterial load in cerebella indicated that CRO and CRO + DOX were equally effective at controlling meningococcal replication. No differences in survival were observed between mice treated with CRO (94.4%) or CRO + DOX (95.5%), (p > 0.05). Treatment with CRO + DOX significantly diminished both the number of cerebral hemorrhages (p = 0.029) and the amount of MMP-9 in the brain (p = 0.046) compared to untreated controls, but not to CRO-treated animals (p > 0.05). Levels of inflammatory markers in the brain of mice that received CRO or CRO + DOX were not significantly different (p > 0.05). Overall, there were no significant differences in the parameters assessed between the groups treated with CRO alone or CRO + DOX.

CONCLUSIONS

Treatment with CRO + DOX showed similar bactericidal activity to CRO in vivo, suggesting no antagonist effect of DOX on CRO. Combined therapy significantly improved mouse survival and disease severity compared to untreated animals, but addition of DOX to CRO did not offer significant benefits over CRO monotherapy. In contrast to experimental PM, DOX has no adjunctive activity in experimental MM.

The Potential Role of Matrix Metalloproteinases 8 and 9 and Myeloperoxidase in Predicting Outcomes of Bacterial Meningitis of Childhood

Background

Matrix metalloproteinases (MMPs) and myeloperoxidase (MPO) contribute to the inflammatory cascade in the cerebrospinal fluid (CSF) during bacterial meningitis. We determined levels of MPO, MMP-8, MMP-9, and tissue inhibitor of metalloproteinase- (TIMP-) 1 in the CSF of children with bacterial meningitis and investigated how these inflammatory mediators relate to each other and to the disease outcomes.

Methods

Clinical data and the diagnostic CSF samples from 245 children (median age eight months) with bacterial meningitis were obtained from a clinical trial in Latin America in 1996–2003. MMP-9 levels in the CSF were assessed by zymography, while MMP-8, MPO, and TIMP-1 concentrations were determined with immunofluorometric and enzyme-linked immunosorbent assays.

Results

MPO correlated positively with MMP-8 (rho 0.496, P < 0.001) and MMP-9 (rho 0.153, P = 0.02) but negatively with TIMP-1 (rho -0.361, P < 0.001). MMP-8 emerged as the best predictor of disease outcomes: a CSF MMP-8 concentration above the median increased the odds of death 4.9-fold (95% confidence interval 1.8–12.9).

Conclusions

CSF MMP-8 presented as an attractive prognostic marker in children with bacterial meningitis.

Chemokines and matrix metalloproteinases in cerebrospinal fluid of patients with central nervous system complications caused by varicella-zoster virus

BACKGROUND

Varicella-zoster virus (VZV) is a common viral agent causing central nervous system (CNS) infections including encephalitis, meningitis, and Ramsay Hunt syndrome. Neurological complications occur frequently despite antiviral treatment. Matrix metalloproteinases (MMPs) and cytokines are involved in the neuroinflammatory response during CNS infection. Their role in VZV CNS infections and how they differ between different CNS entities caused by VZV are poorly investigated.

METHODS

We analyzed the levels of 30 chemokines and 9 MMPs in cerebrospinal fluid (CSF) and serum from 66 patients with VZV CNS infections diagnosed by detection of VZV DNA in CSF and concomitant neurological symptoms and compared with a control group (n = 24).

RESULTS

Levels of CCL19, CXCL8, CXCL9, and CXCL10 were significantly increased and surpassing the levels in serum when analyzing all patients with VZV CNS infections whereas CXCL11 was only increased in CSF of patients with VZV meningitis. MMP-2-levels were highly elevated in CSF of all 66 VZV patients. The patients with encephalitis had the most significantly increased levels of MMPs in CSF, and MMP-3, MMP-8, and MMP-12 were exclusively increased in this group, whereas MMP-9 in CSF was increased in the patients with VZV meningitis.

CONCLUSIONS

We show that both chemokines and MMPs are elevated in the CSF of patients with VZV CNS infections. Encephalitis and meningitis patients differed with respect to other chemokines (CXCL11) and MMPs (MMP-3, MMP-8, MMP-9, and MMP-12), indicating that different location of the virus gives rise to qualitative differences in the ensuing inflammatory response. In addition, the pronounced increase of MMPs in CSF of the patients with encephalitis suggests an association to the severity of this manifestation, compared to VZV meningitis and Ramsay Hunt syndrome. The role of MMPs in association to chemokines should be further investigated to evaluate their significance in the neuropathogenesis of VZV CNS infections and as a potential target for new treatment alternatives.

Cerebrospinal Fluid Cathelicidin Correlates With the Bacterial Load and Outcomes in Childhood Bacterial Meningitis

BACKGROUND

Large cerebrospinal fluid (CSF) bacterial load in bacterial meningitis (BM) relates to poor outcome. However, the antimicrobial peptide cathelicidin seems important to host defense. We studied how cathelicidin concentrations and bacterial load in CSF relate in childhood BM and to what extent they may predict the disease outcome.

METHODS

The patient data originated from a large prospective clinical trial in Latin America in 1996-2003 in which the CSF samples were collected on admission (CSF1) and 12-24 hours later (CSF2). The cathelicidin concentrations were measured by enzyme-linked immunosorbent assay and the CSF bacterial load by real-time polymerase chain reaction. This analysis comprised 76 children with meningitis caused by Haemophilus influenzae type b (n = 44), Streptococcus pneumoniae (n = 28) or Neisseria meningitidis (n = 4).

RESULTS

The cathelicidin concentration correlated with the bacterial genome count in both samples (CSF1: ρ = 0.531, P < 0.001; CSF2: ρ = 0.553, P < 0.001). A high CSF1 ratio of cathelicidin to the bacterial genome count was associated with fewer audiologic sequelae (odds ratio: 0.11, 95% confidence interval: 0.02-0.61, P = 0.01) and more favorable neurologic outcomes (odds ratio: 3.95, 95% confidence interval: 1.22-12.8, P = 0.02), but not with better survival.

CONCLUSIONS

In conclusion, CSF cathelicidin and the bacterial load were closely related in childhood BM. A high initial cathelicidin-to-bacterial genome count ratio predicted better outcomes in survivors.

Predicting Outcome of Childhood Bacterial Meningitis With a Single Measurement of C-Reactive Protein

INTRODUCTION

C-reactive protein (CRP), a marker of inflammation, shows high serum levels in invasive bacterial infections. We investigated the potential of a single CRP measurement at different phases of acute childhood bacterial meningitis to predict outcomes.

METHODS

Using whole-blood finger-prick samples with no centrifugation, CRP was measured quantitatively on arrival and on day 3 or 4 in children participating in 2 prospective, randomized, double-blind treatment studies conducted in Latin America or Angola. The results were compared with patient outcomes.

RESULTS

Although initial CRP values from 669 children gave useful prognostic information, the 3rd or 4th day measurements taken from 275 children associated significantly with seizures, slow recovery and low scores on the Glasgow Outcome Scale, with odds ratios for CRP values above the median (62 mg/L) ranging from 2 to 6, 2 to 5, and 3 to 5 (Latin America-Angola), respectively. Hearing impairment, although not full deafness, was 3 to 7 times more likely if CRP was above the median soon after hospitalization.

CONCLUSIONS

Especially in resource-poor settings, clinicians have few simple-enough tools to identify the child with meningitis who requires maximum attention. CRP is a worthy addition.

Bacterial meningitis: insights into pathogenesis and evaluation of new treatment options: a perspective from experimental studies

Bacterial meningitis is associated with high mortality and morbidity rates. Bacterial components induce an overshooting inflammatory reaction, eventually leading to brain damage. Pathological correlates of neurofunctional deficits include cortical necrosis, damage of the inner ear and hippocampal apoptosis. The hippocampal dentate gyrus is important for memory acquisition and harbors a neuronal stem cell niche, thus being potentially well equipped for regeneration. Adjuvant therapies aimed at decreasing the inflammatory reaction, for example, dexamethasone, and those protecting the brain from injury have been evaluated in animal models of the disease. They include nonbacteriolytic antibiotics (e.g., daptomycin), metalloproteinase inhibitors and modulators of the immunological response, for example, granulocyte colony-stimulating factor. Increasing research interest has recently been focused on interventions aimed at supporting regenerative processes.

Changes in MMP-9 and TIMP-1 Concentrations in Cerebrospinal Fluid after 1 Week of Treatment of Childhood Bacterial Meningitis

We explored the changes of the initially highly upgraded cerebrospinal fluid matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of MMP 1 (TIMP-1) response during recovery of childhood bacterial meningitis and their association with outcome. The sizes of these changes varied substantially, but a steeper decrease in the MMP-9 and an increase of the TIMP-1 concentrations augured a better outcome.