Cerebrospinal fluid TNF-α, IL-6, and IL-8 in children with bacterial meningitis

Biomarkers in paediatric bacterial meningitis: a systematic review and meta-analysis of diagnostic test accuracy

BACKGROUND

Biomarkers for paediatric bacterial meningitis are essential for an accurate diagnosis.

OBJECTIVES

To perform a systematic review of diagnostic accuracy on cerebrospinal fluid (CSF) and blood biomarkers for paediatric bacterial meningitis.

DATA SOURCES

Databases Medline, Excerpta Medica Database, Scopus, and Web of Science were used.

STUDY ELIGIBILITY CRITERIA

Eligible studies were those on novel diagnostic CSF and blood biomarkers from which data on biomarker concentration or diagnostic accuracy could be abstracted.

PARTICIPANTS

Paediatric patients (0-18 years) suspected of a central nervous system (CNS) infection.

ASSESSMENT OF RISK OF BIAS

The Quality Assessment tool for Diagnostic Accuracy Studies (QUADAS)-2 tool was used to assess risk of bias.

METHODS OF DATA SYNTHESIS

The difference in biomarker concentrations were assessed by calculating standardized and weighted mean differences. A random-effects meta-analysis model was used. Hierarchical summary receiver-operating characteristic curves were constructed.

RESULTS

We identified 3435 studies, of which 112 articles on 113 individual biomarkers (CSF n = 90 and blood n = 23) were included. In CSF, C-reactive protein (CRP), Interleukin (IL)-6, Tumor necrosis factor (TNF)-α, and Interleukin (IL)-8 showed the largest mean differences between bacterial meningitis and viral meningitis and IL-6, TNF-α, and IL-8 between bacterial meningitis and no CNS infection/inflammation. CSF CRP and ferritin showed excellent discrimination for bacterial versus viral meningitis (summary area under the curve [sAUC] 0.94; 95% CI, 0.92-0.97, sAUC 0.94; 95% CI, 0.90-1.0). CSF IL-6 and procalcitonin showed excellent discrimination for bacterial versus nonbacterial meningitis and versus no CNS infection/inflammation (sAUC IL-6: 0.98; 95% CI, 0.96-1.00, sAUC procalcitonin: 0.96; 95% CI, 0.94-0.99). Procalcitonin in blood showed good discrimination (AUC, 0.89; 95% CI, 0.68-1.00).

DISCUSSION

We identified several CSF biomarkers with high diagnostic accuracy for the diagnosis of bacterial meningitis, including IL-6, procalcitonin, CRP, and ferritin. None of the blood biomarkers exhibited excellent discrimination for paediatric bacterial meningitis. Validation of these biomarkers in prospective, well-designed studies of diagnostic accuracy performed in children with suspected meningitis is needed.

Escherichia Coli K1-colibactin meningitis induces microglial NLRP3/IL-18 exacerbating H3K4me3-synucleinopathy in human inflammatory gut-brain axis

Escherichia coli K1 (E. coli K1) meningitis early occurs in the gastrointestinal and causes severe damage to the central nervous system, including lifelong neurological complications in survivors. However, the cellular mechanism by which E. coli K1 may cause neuropathies is not well understood due to the lack of relevant human multi-organ models for studying multifaceted systemic inflammation across the gut-brain axis. Here, we reconstruct a multicellular model of the human gut-brain axis to identify the neuropathogenic mechanism driven by E. coli K1-colibactin meningitis. We observed that E. coli K1-genotoxic colibactin induced intestinal and peripheral interleukin 6, causing the blood-brain barrier injury and endothelial inflammation via the p38/p65 pathways. Serpin-E1 from the damaged cerebral endothelia induces reactive astrocytes to release IFN-γ, which reduces microglial phagocytosis of E. coli K1 and exacerbates detrimental neuroinflammation via NLRP3/IL-18 axis. Microglial IL-18 elevates neuronal reactive oxidative stress that worsens DNA double-strand breaks in E. coli K1-infected neurons, leading to H3K4 trimethylation and phosphorylation of alpha-synuclein. Our findings suggest therapeutic strategies for post-bacterial meningitis treatment to potentially prevent the initiation of synucleinopathy.

Diagnostic Accuracy of Procalcitonin in Bacterial Infections of the CNS: An Updated Systematic Review, Meta-Analysis, and Meta-Regression

OBJECTIVES

To evaluate diagnostic accuracy of serum and cerebrospinal fluid (CSF) procalcitonin for diagnosing CNS bacterial infections.

DATA SOURCES

We searched MEDLINE, Cochrane Central Register of Controlled Trials, and International Web of Science databases from January 1, 2016, to September 30, 2022.

STUDY SELECTION

Randomized controlled trials and observational studies, either prospective or retrospective, focusing on procalcitonin as a biomarker for CNS infections.

DATA EXTRACTION

We screened and extracted studies independently and in duplicate. We assessed risk of bias using the revised Quality Assessment for Studies of Diagnostic Accuracy tool. Data for diagnostic sensitivity and specificity were pooled using the bivariate or hierarchical model, as appropriate.

DATA SYNTHESIS

Of 5,347 citations identified, 23 studies were included. Overall, CSF procalcitonin showed slightly higher pooled sensitivity, specificity, and positive likelihood ratio compared with serum procalcitonin. In adults, pooled sensitivity of CSF procalcitonin was 0.89 (95% CI, 0.71-0.96), specificity 0.81 (95% CI, 0.66-0.91); pooled sensitivity of serum procalcitonin was 0.82 (95% CI, 0.58-0.94), specificity 0.77 (95% CI, 0.60-0.89). In children, pooled sensitivity of CSF procalcitonin was 0.96 (95% CI, 0.88-0.99), specificity 0.91 (95% CI, 0.72-0.97); pooled sensitivity of serum procalcitonin was 0.90 (95% CI, 0.75-0.97), specificity 0.83 (95% CI, 0.67-0.92). In post-neurosurgical patients, pooled sensitivity of CSF procalcitonin was 0.82 (95% CI, 0.53-0.95), specificity 0.81 (95% CI, 0.63-0.91); pooled sensitivity of serum procalcitonin was 0.65 (95% CI, 0.33-0.88), specificity 0.61 (95% CI, 0.41-0.78). Logistic regression revealed between-study heterogeneity higher for serum than CSF procalcitonin. For the latter, threshold variability was found as source of heterogeneity.

CONCLUSIONS

In children and critical post-neurosurgical patients, CSF procalcitonin gains superior sensitivity and specificity compared with serum procalcitonin. Overall, CSF procalcitonin appears to have a higher pooled positive likelihood ratio compared with serum procalcitonin.

Diagnostic Utility of Cerebrospinal Fluid White Blood Cell Components for the Identification of Bacterial Meningitis in Infants

BACKGROUND

To evaluate the diagnostic and predictive utility of cerebrospinal fluid (CSF) white blood cell (WBC) components in the diagnosis of bacterial meningitis in infants discharged from the neonatal intensive care unit (NICU).

METHODS

We identified a cohort of infants discharged from a Pediatrix NICU between 1997 and 2020 who did not have an immunodeficiency, had at least 1 CSF culture collected within the first 120 days of life, and at least 1 CSF laboratory specimen obtained on the day of culture collection. We only included an infant's first CSF culture and excluded cultures from CSF reservoirs and those growing contaminants or nonbacterial organisms. We examined the utility of CSF WBC components to diagnose or predict bacterial meningitis by calculating sensitivity, specificity, positive and negative predictive values, likelihood ratios, and area under the receiver operating curve (AUC) at different cutoff values for each parameter. We performed subgroup analysis excluding infants treated with antibiotics the day before CSF culture collection.

RESULTS

Of the 20 756 infants that met the study inclusion criteria, 320 (2%) were diagnosed with bacterial meningitis. We found (AUC [95% CI]) CSF WBC count (0.76 [0.73-0.79]), CSF neutrophil count (0.74 [0.70-0.78]), and CSF neutrophil percent (0.71 [0.67-0.75]) had the highest predictive values for bacterial meningitis, even when excluding infants with early antibiotic administration.

CONCLUSIONS

No single clinical prediction rule had the optimal discriminatory power for predicting culture-proven bacterial meningitis, and clinicians should be cautious when interpreting CSF WBC parameters in infants with suspected meningitis.

Cytokine profile in patients with acute bacterial meningitis

BACKGROUND

Bacterial meningitis is a life-threatening disease with high mortality and common long-term sequelae. The inflammatory response in the subarachnoid space, modulated by different cytokines, plays a major role in the pathogenesis of acute central nervous system infections. We aimed to examine correlations of interleukin (IL)-6, IL-8, IL-10, IL-12(p40), and tumor necrosis factor (TNF)-α levels with disease severity, complications, and outcome in patients with acute bacterial meningitis.

METHODS

The study involved 30 patients with bacterial meningitis/meningoencephalitis admitted to the University Hospital St. George, Plovdiv over a period of 4 years. Patients were selected based on clinical presentation and laboratory abnormalities, consistent with a neuroinfection. Enzyme-linked immunosorbent assay was used to measure the studied cytokines in both cerebrospinal fluid (CSF) and serum in parallel. For microbiological diagnosis multiplex, polymerase chain reaction, and CSF culture were used.

RESULTS

In patients with acute bacterial meningitis CSF levels of IL-6, IL-8, IL-10, and TNF-α are significantly increased than in serum. CSF TNF-α, CSF IL-8, and CSF IL-10 had a moderate negative correlation to CSF glucose. It was found that serum IL-8 is significantly elevated in patients who experienced neurological complications, have severe clinical course, and in deceased patients. CSF IL-10 is increased only in patients with severe acute bacterial meningitis.

CONCLUSION

Among patients with acute bacterial meningitis serum IL-8 could delineate these with increased risk of neurological complications, severe clinical course, and fatal outcome. Serum IL-8 and CSF IL-10 could be used as indicators of disease severity.

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.

The neurotoxic branch of the kynurenine pathway is highly activated in the central nervous system of patients with pneumococcal meningitis

BACKGROUND

Acute bacterial meningitis (ABM) causes excessive activation of N-methyl-D-aspartate receptors (NMDAr), leading to cortical and hippocampal neuron death. As opposite, enteroviral meningitis is more frequently benign. The kynurenine (KYN) pathway is the major catabolic route of tryptophan (TRP) and some of its metabolites are agonists or antagonists of NMDAr.

METHODS

In order to investigate the pathogen-specific patterns of KYN pathway modulation in the central nervous system of children with acute meningococcal (MM), pneumococcal (PM) or enteroviral (VM) meningitis, the cerebrospinal fluid (CSF) concentrations of TRP, KYN, kynurenic acid (KYNA) and quinolinic acid (QUINA) were evaluated by ultra-high performance liquid chromatography (uHPLC) coupled to mass spectrometry. In addition, CSF levels of IL-6, IL-10 and TNF-α were quantified by multi-analyte flow assay. The data was mined and integrated using statistical and machine learning methods.

RESULTS

The three forms of meningitis investigated herein up-regulated the neurotoxic branch of the KYN pathway within the intrathecal space. However, this response, represented by the concentration of QUINA, was six and nine times higher in PM patients compared to MM or VM, respectively. CSF levels of IL-6, TNF-α, and IL-10 were increased in MM and PM patients when compared to controls. In VM, CSF IL-6 and IL-10, but not TNF-α were increased compared to controls, although not reaching the high levels found in bacterial meningitis. No correlation was found between the concentrations or the ratios of any pair of KYN metabolites and any cytokine or standard cytochemical parameter tested.

CONCLUSIONS

CNS infection with meningococci, pneumococci, and enteroviruses intrathecally activate the KYN pathway, favoring its neurotoxic branch. However, in PM, higher CSF levels of QUINA, compared to MM and VM, may contribute to its poorer neurologic outcome.

Cerebrospinal fluid cytokines and chemokines exhibit distinct profiles in bacterial meningitis and viral meningitis

Differential diagnosis of bacterial meningitis (BM) and viral meningitis (VM) is a critical clinical challenge, as the early and accurate identification of the causative agent determines the appropriate treatment regimen and markedly improves patient outcomes. Clinical and experimental studies have demonstrated that the pathogen and the host immune response contribute to mortality and neurological sequelae. As BM is associated with the activation of an inflammatory cascade, the patterns of pro- and anti-inflammatory cytokines/chemokines (CTs/CKs) present in the cerebrospinal fluid (CSF) in response to the immune assault may be useful as sensitive markers for differentiating BM from VM. In the present study, the ability of CTs/CKs in the CSF to differentiate between BM and VM was investigated. For this, biochemical markers and CT/CK profiles were analysed in 145 CSF samples, divided into three groups: BM (n=61), VM (n=58) and the control group (C; n=26) comprising patients with meningism. The CSF concentrations of monocyte chemoattractant protein-1, interleukin (IL)-8, IL-1β, IL-6, macrophage inflammatory protein-1α (MIP-1α), epithelial-neutrophil activating peptide, IL-10, tumour necrosis factor-α (TNF-α), proteins and white blood cells were significantly higher and the CSF glucose level was significantly lower in the BM group compared with the VM and C groups (P<0.01). Correlation analysis identified 28 significant correlations between various CTs/CKs in the BM group (P<0.01), with the strongest positive correlations being for TNF-α/IL-6 (r=0.75), TNF-α/MIP-1α (r=0.69), TNF-α/IL-1β (r=0.64) and IL-1β/MIP-1α (r=0.64). To identify the optimum CT/CK patterns for predicting and classifying BM and VM, a dataset of 119 BM and VM samples was divided into training (n=90) and testing (n=29) subsets for use as input for a Random Forest (RF) machine learning algorithm. For the 29 test samples (15 BM and 14 VM), the RF algorithm correctly classified 28 samples, with 92% sensitivity and 93% specificity. The results show that the patterns of CT/CK levels in the CSF can be used to aid discrimination of BM and VM.

One-year-old boy with refractory Listeria monocytogenes meningitis due to persistent hypercytokinemia

We had a case of Listeria monocytogenes (LM) meningitis complicated with hypercytokinemia and hemophagocytic lymphohistiocytosis in a healthy 22-month-old boy. He was admitted to our hospital with a fever, vomiting, mild consciousness disturbances, and extraocular muscle paralysis. Magnetic resonance imaging (MRI) revealed bilateral deep white matter lesions. After receiving ampicillin, meropenem, and gentamicin, his cerebrospinal fluid (CSF) culture results turned negative on the third day of hospitalization. However, the fever intermittently persisted, and it took approximately 40 days to completely resolve. During this period, various inflammatory cytokine levels, particularly neopterin, in the blood and CSF remained elevated. Therefore, long-term administration of corticosteroids in addition to antibiotics was required. The use of dexamethasone appeared to be effective for neurological disorders such as consciousness disturbance and extraocular muscle paralysis associated with abnormal brain MRI findings. LM meningitis may present with encephalopathy and persistent fever due to hypercytokinemia. In such cases, corticosteroid therapy should be considered.

Inflammatory Markers Combined With Metalloproteinase-9, Neopterin, and S100B Concentrations May Indicate the Pathogenesis of Central Nervous System Diseases in Children

The identification of central nervous system inflammation etiology leads to adjusted therapy. We analyzed the potential inflammatory and neuro-axonal damage markers in children. Our target was to correlate the findings with a disease's course or a sequalae risk and assess their clinical usefulness. The study included 96 children with symptoms of central nervous system inflammation who underwent diagnostics. The research group involved 24 children with autoimmune disorders and 31 with neuroinfection. The control group included patients with both etiologies excluded. We analyzed the results of routine laboratory tests together with chosen serum (neopterin, interleukin [IL]-1β, IL-6) and CSF (metalloproteinase [MMP]-9, S100B protein) markers. In the whole cohort, CSF MMP-9 correlated with CSF cytosis and serum IL-6 and CRP. In the undivided neuroinflammatory group, CSF S100B correlated with serum IL-6 and IgM concentrations. CSF cytosis was associated with CSF MMP-9 and serum neopterin levels. Among the infective patients, IL-6 was linked with increased CSF MMP-9. We conclude that astroglial protein S100B, neopterin, and cytokine concentrations may enable predicting long-term consequences, whereas CSF MMP-9 concentration may reflect the actual central nervous system injury regardless of etiology.

Group B Streptococcal Neonatal Meningitis

Neonatal bacterial meningitis is a devastating disease, associated with high mortality and neurological disability, in both developed and developing countries. Streptococcus agalactiae, commonly referred to as group B Streptococcus (GBS), remains the most common bacterial cause of meningitis among infants younger than 90 days. Maternal colonization with GBS in the gastrointestinal and/or genitourinary tracts is the primary risk factor for neonatal invasive disease. Despite prophylactic intrapartum antibiotic administration to colonized women and improved neonatal intensive care, the incidence and morbidity associated with GBS meningitis have not declined since the 1970s. Among meningitis survivors, a significant number suffer from complex neurological or neuropsychiatric sequelae, implying that the pathophysiology and pathogenic mechanisms leading to brain injury and devastating outcomes are not yet fully understood. It is imperative to develop new therapeutic and neuroprotective approaches aiming at protecting the developing brain. In this review, we provide updated clinical information regarding the understanding of neonatal GBS meningitis, including epidemiology, diagnosis, management, and human evidence of the disease's underlying mechanisms. Finally, we explore the experimental models used to study GBS meningitis and discuss their clinical and physiologic relevance to the complexities of human disease.

Deciphering the TLR transcriptome and downstream signaling pathway in cerebrospinal fluid in pediatric meningitis

OBJECTIVE/DESIGN

Pediatric meningitis is characterized by a colossal inflammatory response to the pathogen in the central nervous system (CNS). This unabated inflammatory response persists even after the removal of the pathogen by antibiotics/steroids causing collateral damage to CNS tissue. Toll-like receptors (TLRs) are the key players in the recognition and elicitation of innate-immune response against bacterial/viral components in cerebrospinal fluid (CSF). Till date, the precise understanding of TLR-triggered inflammatory response in pediatric meningitis is lacking. The present study was designed to delineate the role of TLR transcriptome and downstream signaling pathways in CSF of pediatric meningitis.

METHODS

Children in the age group of > 3 months to 12 years with pediatric meningitis were included. A total of 249 cases of pediatric meningitis (bacterial = 89, viral = 160) were included. In addition, 71 children who tested negative to the pathogen in CSF tap and did not have signs of infection clinically constituted the controls. RNA was extracted from the CSF samples of both cases and controls. The relative gene expression profile of 42 TLR signaling pathway genes was performed. For the analysis of secretory cytokines and chemokines in CSF, Luminex assay was performed.

RESULTS

We report global upregulation of TLR genes in patients with acute bacterial meningitis (ABM). The downstream signaling molecules were upregulated as well. The CSF of pediatric ABM patients revealed a predominant pro-inflammatory milieu marked by increased levels of pro-inflammatory cytokines. A significant correlation between poor clinical outcomes of patients and an increased expression of TLR/pro-inflammatory cytokine genes was observed.

CONCLUSION

Our findings provide support for future studies exploring TLR-based adjunct therapy to limit the neurological sequelae, owing to persistent inflammation in pediatric ABM patients.

Cognitive and Neuronal Link With Inflammation: A Longitudinal Study in People With and Without HIV Infection

BACKGROUND

Across many settings, lack of virologic control remains common in people with HIV (PWH) because of late presentation and lack of retention in care. This contributes to neuronal damage and neurocognitive impairment, which remains prevalent. More evidence is needed to understand these outcomes in both PWH and people without HIV (PWOH).

METHODS

We recruited PWH initiating antiretroviral therapy and PWOH at 2 sites in the United States. One hundred eight adults were enrolled (56 PWOH and 52 PWH), most of whom had a second assessment at least 24 weeks later (193 total assessments). Tumor necrosis factor alpha, monocyte chemotactic protein-1 (MCP-1), neopterin, soluble CD14, and neurofilament light chain protein (NFL) were measured in plasma and cerebrospinal fluid (CSF). Using multivariate models including Bayesian model averaging, we analyzed factors associated with global neuropsychological performance (NPT-9) and CSF NFL at baseline and over time.

RESULTS

At baseline, higher CSF MCP-1 and plasma sCD14 were associated with worse NPT-9 in PWH, while CSF HIV RNA decrease was the only marker associated with improved NPT-9 over time. Among PWH, higher CSF neopterin was most closely associated with higher NFL. Among PWOH, higher CSF MCP-1 was most closely associated with higher NFL. After antiretroviral therapy initiation, decrease in CSF MCP-1 was most closely associated with NFL decrease.

CONCLUSION

Monocyte-associated CSF biomarkers are highly associated with neuronal damage in both PWH and PWOH. More research is needed to evaluate whether therapies targeting monocyte-associated inflammation may ameliorate HIV-associated neurobehavioral diseases.

Combined testing of cerebrospinal fluid IL-12 (p40) and serum C-reactive protein as a possible discriminator of acute bacterial neuroinfections

INTRODUCTION

Central nervous system infections (CNS) are life-threatening diseases, with meningitis being the most common. Viral infections are usually self-limiting diseases but bacterial pathogens are associated with higher mortality rates and persistent neurological sequelae. We aimed to study the role of IL-6, IL-8, IL-10, IL-12(p40), TNF-α cytokines, classical cerebrospinal fluid (CSF) parameters, and serum C-reactive protein levels (CRP) for discriminating bacterial from viral central nervous system infections.

MATERIAL AND METHODS

This prospective study included 80 patients with clinical signs and abnormal cerebrospinal fluid laboratory findings typical for neuroinfection admitted to St. George University Hospital-Plovdiv. Routine methods such as direct microscopy, culturing and identification were used for microbiological analysis as well as latex-agglutination test and multiplex PCR. Cytokines' concentrations were measured by ELISA. CRP and CSF parameters were collected from the patients' medical records.

RESULTS

We observed the highest discriminatory power among cytokines for cerebrospinal IL-12(p40) (AUC = 0.925; p = 0.000). CSF protein levels were the best predictor for bacterial neuroinfection (AUC = 0.973; p = 0.000). The AUC for the serum CRP as a stand-alone biomarker was estimated to be 0.943. The discriminatory power can be increased up to 0.995 (p = 0.000) when combining cerebrospinal fluid IL-12(p40) and serum CRP, with an optimal cut-off value of 144 (Sensitivity 100%; Specificity 90.9%).

CONCLUSION

The combined testing of CSF IL-12(p40) and serum CRP is associated with the highest diagnostic accuracy.

Toll-like receptor linked cytokine profiles in cerebrospinal fluid discriminate neurological infection from sterile inflammation

Rapid determination of an infective aetiology causing neurological inflammation in the cerebrospinal fluid can be challenging in clinical practice. Post-surgical nosocomial infection is difficult to diagnose accurately, as it occurs on a background of altered cerebrospinal fluid composition due to the underlying pathologies and surgical procedures involved. There is additional diagnostic difficulty after external ventricular drain or ventriculoperitoneal shunt surgery, as infection is often caused by pathogens growing as biofilms, which may fail to elicit a significant inflammatory response and are challenging to identify by microbiological culture. Despite much research effort, a single sensitive and specific cerebrospinal fluid biomarker has yet to be defined which reliably distinguishes infective from non-infective inflammation. As a result, many patients with suspected infection are treated empirically with broad-spectrum antibiotics in the absence of definitive diagnostic criteria. To begin to address these issues, we examined cerebrospinal fluid taken at the point of clinical equipoise to diagnose cerebrospinal fluid infection in 14 consecutive neurosurgical patients showing signs of inflammatory complications. Using the guidelines of the Infectious Diseases Society of America, six cases were subsequently characterized as infected and eight as sterile inflammation. Twenty-four contemporaneous patients with idiopathic intracranial hypertension or normal pressure hydrocephalus were included as non-inflamed controls. We measured 182 immune and neurological biomarkers in each sample and used pathway analysis to elucidate the biological underpinnings of any biomarker changes. Increased levels of the inflammatory cytokine interleukin-6 and interleukin-6-related mediators such as oncostatin M were excellent indicators of inflammation. However, interleukin-6 levels alone could not distinguish between bacterially infected and uninfected patients. Within the patient cohort with neurological inflammation, a pattern of raised interleukin-17, interleukin-12p40/p70 and interleukin-23 levels delineated nosocomial bacteriological infection from background neuroinflammation. Pathway analysis showed that the observed immune signatures could be explained through a common generic inflammatory response marked by interleukin-6 in both nosocomial and non-infectious inflammation, overlaid with a toll-like receptor-associated and bacterial peptidoglycan-triggered interleukin-17 pathway response that occurred exclusively during infection. This is the first demonstration of a pathway dependent cerebrospinal fluid biomarker differentiation distinguishing nosocomial infection from background neuroinflammation. It is especially relevant to the commonly encountered pathologies in clinical practice, such as subarachnoid haemorrhage and post-cranial neurosurgery. While requiring confirmation in a larger cohort, the current data indicate the potential utility of cerebrospinal fluid biomarker strategies to identify differential initiation of a common downstream interleukin-6 pathway to diagnose nosocomial infection in this challenging clinical cohort.

Role of Bacterial and Host DNases on Host-Pathogen Interaction during Streptococcus suis Meningitis

Streptococcus suis is a zoonotic agent causing meningitis in pigs and humans. Neutrophils, as the first line of defense against S. suis infections, release neutrophil extracellular traps (NETs) to entrap pathogens. In this study, we investigated the role of the secreted nuclease A of S. suis (SsnA) as a NET-evasion factor in vivo and in vitro. Piglets were intranasally infected with S. suis strain 10 or an isogenic ssnA mutant. DNase and NET-formation were analyzed in cerebrospinal fluid (CSF) and brain tissue. Animals infected with S. suis strain 10 or S. suis 10ΔssnA showed the presence of NETs in CSF and developed similar clinical signs. Therefore, SsnA does not seem to be a crucial virulence factor that contributes to the development of meningitis in pigs. Importantly, DNase activity was detectable in the CSF of both infection groups, indicating that host nucleases, in contrast to bacterial nuclease SsnA, may play a major role during the onset of meningitis. The effect of DNase 1 on neutrophil functions was further analyzed in a 3D-cell culture model of the porcine blood–CSF barrier. We found that DNase 1 partially contributes to enhanced killing of S. suis by neutrophils, especially when plasma is present. In summary, host nucleases may partially contribute to efficient innate immune response in the CSF.

Chitosan-Gentamicin Conjugate Hydrogel Promoting Skin Scald Repair

Our earlier research indicated that chitosan-gentamicin conjugate (CS-GT) possesses superior antimicrobial activity and good water solubility. To develop CS-GT-based scald dressings, the antibacterial properties of CS-GT were further studied, and the biosafety of CS-GT and the healing mechanism of CS-GT hydrogel was systematically explored in this article. It was found that cell viability shows a declined inclination with the prolonged culture time and the increased concentration of CS-GT. After three day’s culture, the cell viability could still remain at 79.72% when CS-GT concentration was as high as 1000 μg/mL. On the other hand, the hemolysis rate of CS-GT was lower than 5% when its concentration is 800 μg/mL. Therefore CS-GT has good cytocompatibility and hemocompatibility. A wound-healing experiment has shown that the skin healing rate of CS-GT hydrogel was the highest at 99.61%, followed by the positive control (wet burn ointment) 94.98%, GT hydrogel 87.50%, and matrix 77.39%. The blank control group, however, possessed the lowest healing rate of 75.45%. Further analysis indicated that CS-GT hydrogel could promote the synthesis of total protein (TP) in skin granulation tissue, resulting in the enhanced hydroxyproline (HYP) content, which facilitated collagen fibrogenesis, reduced cytokine expression in an inflammatory response, and, ultimately, accelerated wound healing. To sum up, CS-GT hydrogel is a promising scald dressing.

Cerebrospinal fluid inflammatory markers in children with aseptic meningitis

Aseptic meningitis is one of the most common inflammatory disorders of the meninges of the central nervous system (CNS). The aim of our study was to investigate the cytokine profiles in the CSF and in the serum of children with aseptic meningitis to determine their role in CNS inflammation. Sixty-eight (68) children were kept under observation. Cytokine profile of CSF and blood (based on the results of determining of IL-1β, IL-4, IL-10, TNF-α levels) and procalcitonin in children were revealed, meningitis severity were estimated by AMSS score. It was found that in the majority of patients with aseptic meningitis, the levels of IL-1β, TNF-α, IL-10 in CSF were increased and exceeded the serum cytokines levels. The severe course of meningitis was characterized by significantly higher concentrations of IL-1β and TNF-α in CSF, which was confirmed by positive correlation between AMSS score and IL-1β concentration (r=0.46, p<0.01), IL-10 (r=0.32, p<0.01), TNF-α (r=0.62, p<0.05). The IL-10/TNF-α ratio was – 17.8. PCT level in CSF was within normal limits in the majority of patients with meningitis. Increasing of anti-inflammatory cytokine levels in aseptic meningitis contributes to preventing of excessive inflammatory/immune responses in the brain. This can cause a longer diseases course and a longer recovery period. This can an indicate active production of cytokines in the central nervous system due to intrathecal inflammation and activation of immune responses caused by viral infection, but not due to penetration across the blood-brain barrier.

Cytokine characteristic of cerebrospinal fluid from children with enteroviral meningitis compared to bacterial meningitis

Background

Enteroviruses are the most common etiological agent for viral encephalitis, but it is uncertain whether the cytokines have the ability to differentiate enteroviral meningitis (EVM) from bacterial meningitis (BM).

Methods

A retrospective study was performed at the Children's Hospital, Zhejiang University School of Medicine from August 2016 and August 2019. CSF and/or blood specimens were collected for microbiological culture, viruses, and cytokine detection.

Results

Forty‐three patients were confirmed with meningitis, 27 patients with EVM, and 16 with BM. Children with EVM were older compared with BM and Control group (P < .001). The most common presenting symptom in children with EVM was fever (96.3%) followed by headache (88.9%) and vomiting (66.7%). The occurrence of seizure was lower in both EVM and BM groups (P < .001). Serum IL‐6 and serum IL‐10 were lower in EVM group than BM (P = .02) and control group (IL‐6, P = .01; IL‐10, P < .001). IL‐6, IL‐10, and IFN‐γ levels showed obviously increase in CSF (P < .001, respectively) in EVM group, while only IL‐6 increased in CSF (P < .001) in BM group. CSF concentrations of cytokines IL‐6, IL‐10, TNF, and IFN‐γ in children with EVM and BM were both higher than Control group (P < .001). But compared EVM group to BM group, CSF IL‐2 (P = .13), IL‐6 (P = .37), IL‐10 (P = .98), TNF (P = .54), and IFN‐γ (P = .53) showed no difference between two groups.

Conclusions

CSF cytokines elevated in both virus and bacterial meningitis, while serum elevation only occurred in bacterial infection. Still, we could not distinguish enteroviral meningitis from bacterial meningitis with the parameters of CSF cytokines IL‐2, IL‐6, IL‐10, TNF, and IFN‐γ.

Aptamer-modified gold nanoparticles for rapid aggregation-based detection of inflammation: an optical assay for interleukin-6

A proof-of-concept aptamer-based optical assay is described for the determination of the immuno signalling molecule interleukin-6 (IL-6), a key marker of acute inflammation. The optical assay is based on the aggregation of gold nanoparticles (AuNP) coated in two complimentary "sandwich-style" aptamers, each with different IL-6 target moieties. IL-6 will recognise the complimentary aptamer pair and bind to it, thereby causing the aggregation of the corresponding functionalised nanoparticles. The aggregation of the AuNPs after exposure to IL-6 induces a visible colour change from red to pink, with a corresponding change in the absorption maximum from 520 to 540 nm. The change in the absorption maximum can be monitored visually, or by using a spectrophotometer or a plate reader. The optimal size and functionalisation of aptamer-coated AuNPs, and the potential assay formats were investigated using UV-vis spectrophotometry, transmission electron microscopy, and dynamic light scattering. The optical assay was applied for detecting mouse IL-6 in a mixed protein solution as a representative biological sample. The assay works in the 3.3 to 125 μg·mL-1 IL-6 concentration range, and the detection limit (at S/N = 3) is 1.95 μg·mL-1. This study was performed as a proof-of-concept demonstration of this versatile assay design, with a view to developing a similar assay for use in clinical samples in future. Graphical abstractSchematic representation of the aggregation of aptamer-functionalised nanoparticles in the presence of interleukin-6 (IL-6). The presence of mouse IL-6 in a mixed protein solution leads to a visible colour change, and a change in the absorption spectrum of the nanoparticles.

Significance of cerebrospinal fluid inflammatory markers for diagnosing external ventricular drain–associated ventriculitis in patients with severe traumatic brain injury

Objective

The aim of this study was to investigate the diagnostic potential of the inflammatory markers interleukin-6 (IL-6), total leukocyte count (TLC), and protein in the CSF and IL-6, C-reactive protein, and white blood cell count in the serum for the early diagnosis of ventriculitis in patients with traumatic brain injury (TBI) and an external ventricular drain compared with patients without ventriculitis.

Methods

Retrospective data from 40 consecutive patients with TBI and an external ventricular drain treated in the authors’ intensive care unit between 2013 and 2017 were analyzed. For all markers, arithmetical means and standard deviations, area under the curve (AUC), cutoff values, sensitivity, specificity, positive likelihood ratio (LR), and negative LR were calculated and correlated with presence or absence of ventriculitis.

Results

There were 35 patients without ventriculitis and 5 patients with ventriculitis. The mean ± SD IL-6 concentration in CSF was significantly increased, with 6519 ± 4268 pg/mL at onset of ventriculitis compared with 1065 ± 1705 pg/mL in patients without ventriculitis (p = 0.04). Regarding inflammatory markers in CSF, IL-6 showed the highest diagnostic potential for differentiation between the presence and absence of ventriculitis (AUC 0.938, cutoff 4064 pg/mL, sensitivity 100%, specificity 92.3%, positive LR 13, and negative LR 0), followed by TLC (AUC 0.900, cutoff 64.5 /µL, sensitivity 100%, specificity 80%, positive LR 5.0, and negative LR 0) and protein (AUC 0.876, cutoff 31.5 mg/dL, sensitivity 100%, specificity 62.5%, positive LR 2.7, and negative LR 0).

Conclusions

The level of IL-6 in CSF has the highest diagnostic value of all investigated inflammatory markers for detecting ventriculitis in TBI patients at an early stage. In particular, CSF IL-6 levels higher than the threshold of 4064 pg/mL were significantly associated with the probability of ventriculitis.

Identification of Potential Cerebrospinal Fluid Biomarkers To Discriminate between Infection and Sterile Inflammation in a Rat Model of Staphylococcus epidermidis Catheter Infection

Staphylococcus epidermidis cerebrospinal fluid (CSF) shunt infection is a common complication of hydrocephalus treatment, creating grave neurological consequences for patients, especially when diagnosis is delayed. The current method of diagnosis relies on microbiological culture; however, awaiting culture results may cause treatment delays, or culture may fail to identify infection altogether, so newer methods are needed.

Staphylococcus epidermidis cerebrospinal fluid (CSF) shunt infection is a common complication of hydrocephalus treatment, creating grave neurological consequences for patients, especially when diagnosis is delayed. The current method of diagnosis relies on microbiological culture; however, awaiting culture results may cause treatment delays, or culture may fail to identify infection altogether, so newer methods are needed. To investigate potential CSF biomarkers of S. epidermidis shunt infection, we developed a rat model allowing for serial CSF sampling. We found elevated levels of interleukin-10 (IL-10), IL-1β, chemokine ligand 2 (CCL2), and CCL3 in the CSF of animals implanted with S. epidermidis-infected catheters compared to sterile controls at day 1 postinfection. Along with increased chemokine and cytokine expression early in infection, neutrophil influx was significantly increased in the CSF of animals with infected catheters, suggesting that coupling leukocyte counts with inflammatory mediators may differentiate infection from sterile inflammation. Mass spectrometry analysis revealed that the CSF proteome in sterile animals was similar to that in infected animals at day 1; however, by day 5 postinfection, there was an increase in the number of differently expressed proteins in the CSF of infected compared to sterile groups. The expansion of the proteome at day 5 postinfection was interesting, as bacterial burdens began to decline by this point, yet the CSF proteome data indicated that the host response remained active, especially with regard to the complement cascade. Collectively, these results provide potential biomarkers to distinguish S. epidermidis infection from sterile postoperative inflammation.

Role of beta-2-microglobulin as a biomarker in very preterm and extremely preterm infants with CNS inflammation

Background

Premature infants are at risk for severe sepsis and meningitis, both infections associated with high mortality and morbidity. Cerebro-spinal fluid (CSF) culture is the gold standard method for meningitis diagnosis, but interpretation of biochemical parameters of CSF is essential at the moment of the analysis in order to start the appropriate treatment. The main objective of this study was to determine whether levels of CSF beta-2-microglobulin (B2M) were elevated in preterm infants with CNS infections or other inflammatory processes, and to establish if there were differences in B2M concentrations amongst various inflammatory settings (sepsis, meningitis, and progressive post-hemorrhagic ventricular dilatation (PHVD)).

Methods

This is a retrospective study of all very preterm and extremely preterm infants (< 32 weeks of gestation) admitted to our NICU between 2012 and 2017. All those who underwent a lumbar puncture during their stay as part of a sepsis work-up or PHVD were considered for inclusion. CSF biochemical parameters and B2M were tested in all of the patients.

Results

Fifty-nine patients were included in the study. In patients with CNS infections, the median value of B2M was 8.69 mg/L (3.92–18.5). B2M levels above 3.92 mg/L showed greater sensitivity and specificity than leukocyte levels in discriminating between patients with CNS infections or other inflammatory processes and those without CNS inflammation.

Conclusions

In this population, CSF B2M proved to be an effective biomarker to discriminate between patients with CNS infections and other inflammatory processes and those without CNS inflammation.

Value of MRI enhanced FLAIR sequence examination combined with CSF TNF-α detection in the early diagnosis of neonatal purulent meningitis

This study aimed to investigate the value of MRI enhanced fluid-attenuated inversion recovery (FLAIR) combined with TNF-α in cerebrospinal fluid in the diagnosis of neonatal purulent meningitis. Fifty neonates with purulent meningitis were randomly selected in the purulency group, 50 patients with viral meningitis (VM) in the virus group and 50 neonates without purulent meningitis in the no meningitis group. All neonates were selected from April 2015 to May 2018 in Women and Children's Hospital (Linyi, China). Clinical baseline data of the three groups were compared, and logistic regression analysis was conducted to analyze the risk factors of the disease. The risk factors of neonatal purulent meningitis include white bold cell count, TNF-α, encephaledema, encephaledema combined with abnormal EEG, erythrocyte sedimentation rate and FLAIR sequential apparent diffusion coefficient (ADC). TNF-α in cerebrospinal fluid combined with FLAIR sequential ADC obtained higher sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy and AUC than single TNF-α in cerebrospinal fluid examination or single FLAIR sequence. MRI enhanced FLAIR sequence scan combined with TNF-α in cerebrospinal fluid has the highest rate in early diagnosis of neonatal purulent meningitis, and it is worthy of clinical promotion.

Tumor necrosis factor alpha and interleukin-1 beta levels in cerebrospinal fluid examination for the diagnosis of ventriculoperitoneal shunt-related ventriculitis

PURPOSE

Ventriculitis is known to develop after chronic inflammation and bacterial invasion of the ventricular surface with a recurrence of shunt infections. The aim of this study is to evaluate the diagnostic value of elevation in cerebrospinal fluid (CSF) interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) together with CSF culture and laboratory test results in the diagnosis of ventriculoperitoneal (VP) shunt-related ventriculitis, which is known to be more problematic than conventional shunt infection.

METHODS

The study included a total of 34 patients with a VP shunt due to hydrocephalus, who presented with a headache, fever, and shunt infection at the Emergency Department and had a pre-diagnosis of ventriculitis. Nineteen patients were diagnosed with shunt-related infection or ventriculitis using the CSF obtained from the shunt pump. The IL-1β and TNF-α levels from the CSF samples of all patients were measured using the Micro ELISA immunoassay method.

RESULTS

CSF direct microscopic observation revealed that the mean cell count, IL-1β level, CRP level, and blood leukocyte level were higher in patients with ventriculitis compared to those diagnosed with shunt infection (p = 0.02, p = 0.009, p = 0.004, and p = 0.009, respectively). The probability of predicting positive culture outcome was 92.7% with 90.9% sensitivity and 82.6% specificity when IL-1β values exceeded 4.0 pg/ml. TNF-α values did not show a significant, reliable pattern compared to IL-1β.

CONCLUSIONS

IL-1β is a reliable parameter which shall be used in the diagnosis of ventriculitis by predicting positive culture outcome with high sensitivity and specificity.

CSF inflammatory markers differ in gram-positive versus gram-negative shunt infections

Background

Cerebrospinal fluid (CSF) shunt placement is frequently complicated by bacterial infection. Shunt infection diagnosis relies on bacterial culture of CSF which can often produce false-negative results. Negative cultures present a conundrum for physicians as they are left to rely on other CSF indices, which can be unremarkable. New methods are needed to swiftly and accurately diagnose shunt infections. CSF chemokines and cytokines may prove useful as diagnostic biomarkers. The objective of this study was to evaluate the potential of systemic and CSF biomarkers for identification of CSF shunt infection.

Methods

We conducted a retrospective chart review of children with culture-confirmed CSF shunt infection at Children’s Hospital and Medical Center from July 2013 to December 2015. CSF cytokine analysis was performed for those patients with CSF in frozen storage from the same sample that was used for diagnostic culture.

Results

A total of 12 infections were included in this study. Patients with shunt infection had a median C-reactive protein (CRP) of 18.25 mg/dL. Median peripheral white blood cell count was 15.53 × 10³ cells/mL. Those with shunt infection had a median CSF WBC of 332 cells/mL, median CSF protein level of 406 mg/dL, and median CSF glucose of 35.5 mg/dL. An interesting trend was observed with gram-positive infections having higher levels of the anti-inflammatory cytokine interleukin (IL)-10 as well as IL-17A and vascular endothelial growth factor (VEGF) compared to gram-negative infections, although these differences did not reach statistical significance. Conversely, gram-negative infections displayed higher levels of the pro-inflammatory cytokines IL-1β, fractalkine (CX₃CL₁), chemokine ligand 2 (CCL2), and chemokine ligand 3 (CCL3), although again these were not significantly different. CSF from gram-positive and gram-negative shunt infections had similar levels of interferon gamma (INF-γ), tumor necrosis factor alpha (TNF-α), IL-6, and IL-8.

Conclusions

This pilot study is the first to characterize the CSF cytokine profile in patients with CSF shunt infection and supports the distinction of chemokine and cytokine profiles between gram-negative and gram-positive infections. Additionally, it demonstrates the potential of CSF chemokines and cytokines as biomarkers for the diagnosis of shunt infection.

Recommendations for cerebrospinal fluid analysis

Diseases of the central nervous system (CNS) mean for the human organism a potentially dangerous situation. An investigation of cerebrospinal fluid (CSF) provides important information about a character of CNS impairment in the decision-making diagnostic and therapeutic algorithm. The authors present a brief overview of available cerebrospinal fluid assays, shortened indication criteria, a recommended algorithm of CSF assessment in different suspected diseases, and a view of the external quality system. The whole portfolio of obtainable CSF methodology is further subdivided according to the adequate choice into the first and inevitable basic routine panel, and following complicated analyses of highly specialized character. The basic panel is considered for standard laboratories, the complete specialized assessment should be provided by a super-consulting laboratory.

High neopterin and IP-10 levels in cerebrospinal fluid are associated with neurotoxic tryptophan metabolites in acute central nervous system infections

Background

The host response to intruders in the central nervous system (CNS) may be beneficial but could also be harmful and responsible for neurologic symptoms and sequelae in CNS infections. This immune response induces the activation of the kynurenine pathway (KP) with the production of neuroactive metabolites. Herein, we explored cytokine and KP responses in cerebrospinal fluid (CSF) and serum in patients with encephalitis, aseptic, and bacterial meningitis.

Methods

Cytokines were measured in CSF and serum by multiplex assay in adult patients with encephalitis of infectious, autoimmune or unknown etiology (n = 10), aseptic meningitis (ASM, n = 25), acute bacterial meningitis (ABM, n = 6), and disease control patients with similar symptoms but without pleocytosis in CSF (n = 42). Liquid chromatography-tandem mass spectrometry (LC-MS/ MS) was used to measure KP metabolites in CSF and serum.

Results

A characteristic pattern of increasing cytokine levels and KP metabolites was found in CSF from encephalitis to ASM, with the highest levels in ABM. In ASM and ABM, most inflammatory mediators, including IL-6, IL-8, and IFN-inducible protein-10 (IP-10), showed markedly elevated levels in CSF compared with serum, indicating production within the CNS. In contrast to most mediators, the highest level of IP-10 was found in the ASM group, suggesting a potential role for IP-10 in aseptic/viral meningitis. Neopterin and IP-10 were associated with marked changes in KP metabolites in CSF with increasing kynurenine/tryptophan ratio reflecting indoleamine 2,3-dioxygenase activity. Neopterin, a marker of IFN-γ activity, was associated with an unfavorable balance between neuroprotective and neurotoxic tryptophan metabolites.

Conclusion

We show that parenchymal and meningeal inflammations in CNS share a characteristic cytokine profile with a general immune response in the CSF with limited influence from the systemic circulation. IFN-γ activity, assessed by neopterin and IP-10 levels, may play a role in the activation of the KP pathway in these patients, potentially mediating neurotoxic effects.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1366-3) contains supplementary material, which is available to authorized users.

Cytokine profiles in cerebrospinal fluid of patients with meningitis at a tertiary general hospital in China

BACKGROUND

There has been a great deal of evidence indicating that cytokines participate in meningeal inflammation. Different cytokine profiles may be presented in central nervous system (CNS) infection due to different pathogens. We have attempted to investigate cytokine profiles in cerebrospinal fluid (CSF) of patients with CNS infection.

METHODS

Forty-three patients with CNS infection including tuberculous meningitis, purulent meningitis and cryptococcal meningitis were enrolled and 11 patients with normal CSF were enrolled as control group. The concentrations of Th1-, Th2- and Th17-type cytokines in CSF were detected using multiplex cytokine assay. Furthermore, the correlation between CSF cytokines and CSF parameters in CNS infection was analyzed.

RESULTS

The CSF levels of IL-1β, IL-4, IL-6, IL-10, IL-17, IL-23, IL-33, IFN-γ, TNF-α and sCD40L among the patients with CNS infection were all higher than control group (all P < 0.05). A remarkable elevation of CSF IL-6 in the patients with CNS infection was observed with the least overlap of the CSF concentrations compared to controls. Moreover, CSF IL-6 levels were strongly negatively correlated with CSF glucose and the CSF/blood glucose ratio (r = -0.4375, P = 0.0042; r = -0.4991, P = 0.0009).

CONCLUSIONS

The excessive activation of immune response characterized by elevated levels of CSF Th1-, Th2- and Th17-type cytokines has been observed during CNS infection. Furthermore, we observed negative correlations between CSF IL-6 levels and CSF glucose and CSF/blood glucose ratio in CNS infection. And we suggested that combined CSF IL-6 levels with CSF glucose may serve as a novel biomarker pool for the differential of CNS infection.

Characteristic Comparison of Meningitis and Non-meningitis of Streptococcus suis in an Experimentally Infected Porcine Model

This study tested the differences of meningitis and non-meningitis of Streptococcus suis (SS). In this study, an infected pig model of streptococcal meningitis was established. Compared with the non-meningitis Streptococcus suis group (JZLQ001 group), the meningitis Streptococcus suis group (JZLQ022) exhibited neurological symptoms, such as ataxia and foaming at the mouth, and the brain showed a large area of congestion at 5 days post-infection (p.i.). Moreover, bacterial counts, white blood cells (WBCs), neutrophils, and blood glucose in the blood reached a peak and were significantly higher than those of the JZLQ001 group at 3 days p.i. These values then decreased at 5 days p.i. However, the content of total protein in the blood was lower in the JZLQ022 group than that in the JZLQ001 group, and the difference was most significant at 5 days p.i. When neurological symptoms appeared on 5 days p.i., the bacterial counts in the brain in the JZLQ022 group were significantly higher than those in the JZLQ001 group. The levels of cytokines in the peripheral blood and cerebrospinal fluid (CSF) were an important indicator of inflammation. By ELISA detection, the secretion levels of IL-6, IL-8, and IL-17 in the peripheral blood in the JZLQ022 group were significantly higher than those in the JZLQ001 group at 12 and 24 h and 3 days p.i.; however, TNF-α showed no difference. At 5 days p.i., the secretion levels of IL-6, IL-8, and IL-17 in the JZLQ022 group were significantly lower than those in the JZLQ001 group. The results were similar in CSF. HE staining revealed that the JZLQ022 group exhibited neuronophagia and hyperemia in the brain, but no change was found in the JZLQ001 group. A further study investigating the impact of meningitis Streptococcus suis on blood-brain barrier (BBB) integrity found that the brain tissue content of endogenous IgG in the JZLQ022 group was significantly higher than that in the JZLQ001 group. The present study demonstrated that pigs infected with meningitis and non-meningitis Streptococcus suis exhibit significant differences in immunological aspects such as bacterial counts, WBCs, neutrophils, blood glucose and total protein in the peripheral blood, the secretion levels of IL-6, IL-8, and IL-17, and BBB integrity. These data provide the necessary evidence to better understand SS meningitis.

The combination of cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 concentrations for the diagnosis of postneurosurgical bacterial meningitis: A prospective study

Background

The differential diagnosis between postneurosurgical bacterial meningitis and aseptic meningitis remains challenging both for the clinician and the laboratory. Combinations of markers, as opposed to single ones, may improve diagnosis and thereby survival.

Methods

This prospective cohort study included patients with suspected bacterial meningitis after neurosurgery. The patients were divided into two groups according to the diagnostic criteria of meningitis involving a postneurosurgical bacterial meningitis group and a postneurosurgical aseptic meningitis group. Four biomarkers, including cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 were assayed separately, and three algorithms were constructed using a linear combination. The area under the receiver operating characteristic curve was used to compare their performances.

Results

A cohort of 112 patients was enrolled in our study. Forty-three patients were diagnosed with postneurosurgical bacterial meningitis, and the cerebrospinal fluid values of their biomarkers were higher in patients with postneurosurgical bacterial meningitis than with postneurosurgical aseptic meningitis. The area under the receiver operating characteristic curves for the detection of postneurosurgical bacterial meningitis were 0.803 (95% confidence interval [CI], 0.724–0.883) for procalcitonin; 0.936 (95% CI, 0.895–0.977) for lactate; 0.771 (95% CI, 0.683–0.860) for interleukin-8; 0.860 (95% CI, 0.797–0.929) for interleukin-10; 0.937 (95% CI, 0.897–0.977) for the composite two-marker test; 0.945 (95% CI, 0.908–0.982) for the composite three-marker test and 0.954 (95% CI, 0.922–0.989) for the composite of all tests. The area under the receiver operating characteristic curves of the combination tests were greater than those of the single markers.

Conclusions

Combining information from several markers improved the diagnostic accuracy in detecting postneurosurgical bacterial meningitis.

Leucine-rich alpha-2 glycoprotein in the cerebrospinal fluid is a potential inflammatory biomarker for meningitis

BACKGROUND

Leucine-rich alpha-2 glycoprotein (LRG) is a novel biomarker for inflammatory diseases. We evaluated the levels of LRG, interleukin (IL)-6, and tumor necrosis factor (TNF)-α in the cerebrospinal fluid (CSF) of children with meningitis.

METHODS

CSF samples from 10 patients with bacterial meningitis (BM) and 10 with aseptic meningitis (AM) were evaluated. Samples from 10 patients with febrile status (FS) were used as controls. LRG levels were measured using a two-site enzyme immunoassay. IL-6 and TNF-α levels were measured using a multiplex bead-based assay. CSF examination of patients with BM at the convalescent stage was also conducted.

RESULTS

LRG and TNF-α levels in patients with BM, and IL-6 levels in patients with BM and AM showed significant increase compared with those in FS. Patients with BM at the convalescent stage showed significantly diminished LRG and IL-6 levels. LRG and IL-6 levels in CSF were indicated to be effective predictors for BM (LRG, AUC = 0.91; IL-6, AUC = 0.85). Only LRG levels showed a significant difference between patients with BM and AM (AUC = 0.78, P = 0.034).

CONCLUSIONS

LRG level could be a sensitive inflammatory biomarker for inflammatory diseases of the central nervous system, comparable with IL-6 level.

Advances in Biomarker-Guided Therapy for Pediatric- and Adult-Onset Neuroinflammatory Disorders: Targeting Chemokines/Cytokines

The concept and recognized components of “neuroinflammation” are expanding at the intersection of neurobiology and immunobiology. Chemokines (CKs), no longer merely necessary for immune cell trafficking and positioning, have multiple physiologic, developmental, and modulatory functionalities in the central nervous system (CNS) through neuron–glia interactions and other mechanisms affecting neurotransmission. They issue the “help me” cry of neurons and astrocytes in response to CNS injury, engaging invading lymphoid cells (T cells and B cells) and myeloid cells (dendritic cells, monocytes, and neutrophils) (adaptive immunity), as well as microglia and macrophages (innate immunity), in a cascade of events, some beneficial (reparative), others destructive (excitotoxic). Human cerebrospinal fluid (CSF) studies have been instrumental in revealing soluble immunobiomarkers involved in immune dysregulation, their dichotomous effects, and the cells—often subtype specific—that produce them. CKs/cytokines continue to be attractive targets for the pharmaceutical industry with varying therapeutic success. This review summarizes the developing armamentarium, complexities of not compromising surveillance/physiologic functions, and insights on applicable strategies for neuroinflammatory disorders. The main approach has been using a designer monoclonal antibody to bind directly to the chemo/cytokine. Another approach is soluble receptors to bind the chemo/cytokine molecule (receptor ligand). Recombinant fusion proteins combine a key component of the receptor with IgG1. An additional approach is small molecule antagonists (protein therapeutics, binding proteins, and protein antagonists). CK neutralizing molecules (“neutraligands”) that are not receptor antagonists, high-affinity neuroligands (“decoy molecules”), as well as neutralizing “nanobodies” (single-domain camelid antibody fragment) are being developed. Simultaneous, more precise targeting of more than one cytokine is possible using bispecific agents (fusion antibodies). It is also possible to inhibit part of a signaling cascade to spare protective cytokine effects. “Fusokines” (fusion of two cytokines or a cytokine and CK) allow greater synergistic bioactivity than individual cytokines. Another promising approach is experimental targeting of the NLRP3 inflammasome, amply expressed in the CNS and a key contributor to neuroinflammation. Serendipitous discovery is not to be discounted. Filling in knowledge gaps between pediatric- and adult-onset neuroinflammation by systematic collection of CSF data on CKs/cytokines in temporal and clinical contexts and incorporating immunobiomarkers in clinical trials is a challenge hereby set forth for clinicians and researchers.

Elevated cerebrospinal fluid tumour necrosis factor is associated with acute and long-term neurocognitive impairment in cerebral malaria

Systemic tumour necrosis factor-α (TNF-α) may contribute to the pathogenesis of cerebral malaria (CM) by promoting endothelial activation and parasite sequestration. However, less is known about the role of central nervous system (CNS) TNF-α in CM. We assessed plasma (n=249) and cerebrospinal fluid (CSF) (n=167) TNF-α levels in Ugandan children with CM, plasma TNF-α in Ugandan community control children (n=198) and CSF TNF-α in North American control children who had recovered from leukaemia (n=13). Plasma and CSF TNF-α were measured by magnetic bead assay. We compared plasma and CSF TNF-α levels in children with CM to mortality, acute and chronic neurologic deficits and long-term neurocognitive impairment. Plasma and CSF TNF-α levels were higher in CM than control children (P<.0001 for both). CSF TNF-α levels were higher in children who had neurologic deficits at discharge or 6-month follow-up (P≤.05 for both). Elevated CSF but not plasma TNF-α was associated with longer coma duration (Spearman's rho .18, P=.02) and deficits in overall cognition in children 5 years and older (β coefficient -.74, 95% CI -1.35 to -0.13, P=.02). The study findings suggest that CNS TNF-α may be involved in the development of acute and chronic neurologic and cognitive sequelae in children with CM.

Neonatal Meningitis: Overcoming Challenges in Diagnosis, Prognosis, and Treatment with Omics

Neonatal meningitis is a devastating condition. Prognosis has not improved in decades, despite the advent of improved antimicrobial therapy and heightened index of suspicion among clinicians caring for affected infants. One in ten infants die from meningitis, and up to half of survivors develop significant lifelong complications, including seizures, impaired hearing and vision, and delayed or arrested development of such basic skills as talking and walking. At present, it is not possible to predict which infants will suffer poor outcomes. Early treatment is critical to promote more favorable outcomes, though diagnosis of meningitis in infants is technically challenging, time-intensive, and invasive. Profound neuronal injury has long been described in the setting of neonatal meningitis, as has elevated levels of many pro- and anti-inflammatory cytokines. Mechanisms of the host immune response that drive clearance of the offending organism and underlie brain injury due to meningitis are not well understood, however. In this review, we will discuss challenges in diagnosis, prognosis, and treatment of neonatal meningitis. We will highlight transcriptomic, proteomic, and metabolomic data that contribute to suggested mechanisms of inflammation and brain injury in this setting with a view toward fruitful areas for future investigation.

Interleukin 6 in the Cerebrospinal Fluid as a Biomarker for Onset of Vasospasm and Ventriculitis After Severe Subarachnoid Hemorrhage

OBJECTIVE

The aim of the study was to investigate the diagnostic potential of interleukin 6 (IL-6) and other soluble biomarkers in serum and cerebrospinal fluid (CSF) for early diagnosis of cerebral vasospasm (cVS_SAH) and external ventricular drain-associated ventriculitis (VC_SAH) and to separate these conditions from aneurysmal subarachnoid hemorrhage (aSAH) without further complication (SAH^w/o/c).

METHODS

The concentrations of serum biomarkers and markers in the CSF were collected in 63 consecutive patients with aSAH and external ventricular drainage. Arithmetical means and standard deviations, area under the curve (AUC), cutoff values (C-OFF), sensitivity (SE), and specificity (SP) were calculated for markers and their correlation with SAH^w/o/c, cVS_SAH, and VC_SAH.

RESULTS

Clinical courses included 27 patients with cVS_SAH, 17 with VC_SAH, and 19 with SAH^w/o/c. Mean ± standard deviation_CSFIL-6 values were 7588 ± 4580 pg/mL at onset of VC_SAH and 4102 ± 4970 pg/mL for cVS_SAH and higher than 234 ± 239 pg/mL in SAH^w/o/c (P < 0.001). _CSFIL-6 showed excellent diagnostic potential for differing between VC_SAH and SAH^w/o/c (AUC, 1.00; C-OFF, 707; SE, 100%; SP, 100%), and a moderate diagnostic potential for differing VC_SAH from cVS_SAH (AUC, 0.757; C-OFF, 3100 pg/Ml; SE, 86.7%; SP, 70.6%). The concentration of _CSFIL-6 within the cVS_SAH group was significantly increased compared with SAH^w/o/c (AUC, 0.937; C-OFF, 530 pg/mL; SE, 87.5%; SP, 91.7%).

CONCLUSIONS

_CSFIL-6 is increased after aSAH in patients with cVS_SAH or VC_SAH. Patients with a _CSFIL-6 level higher than a C-OFF of 3100 pg/mL have an increased likelihood for VC_SAH; patients with _CSFIL-6 levels between 530 and 3100 pg/mL have an increased posttest probability for cVS_SAH.

Cerebrospinal fluid cytokines in the diagnosis of bacterial meningitis in infants

BACKGROUND

Bacterial meningitis poses diagnostic challenges in infants. Antibiotic pretreatment and low bacterial density diminish cerebrospinal fluid (CSF) culture yield, while laboratory parameters do not reliably identify bacterial meningitis. Pro and anti-inflammatory cytokines are elevated in bacterial meningitis and may be useful diagnostic adjuncts when CSF cultures are negative.

METHODS

In a prospective cohort study of infants, we used cytometric bead arrays to measure tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1), IL-6, IL-8, IL-10, and IL-12 in CSF. Receiver operating characteristic (ROC) analyses and Principal component analysis (PCA) were used to determine cytokine combinations that identified bacterial meningitis.

RESULTS

Six hundred and eighty four infants < 6 mo were included; 11 had culture-proven bacterial meningitis. IL-6 and IL-10 were the individual cytokines possessing greatest accuracy in diagnosis of culture proven bacterial meningitis (ROC analyses; area under the concentration-time curve (AUC) 0.91; 0.9103 respectively), and performed as well as, or better than combinations identified using ROC and PCA. CSF cytokines were highly correlated with each other and with CSF white blood cell count (WBC) counts in infants with meningitis. A subset of antibiotic pretreated culture-negative subjects demonstrated cytokine patterns similar to culture positive subjects.

CONCLUSION

CSF cytokine levels may aid diagnosis of bacterial meningitis, and facilitate decision-making regarding treatment for culture negative meningitis.

Edaravone attenuates hippocampal damage in an infant mouse model of pneumococcal meningitis by reducing HMGB1 and iNOS expression via the Nrf2/HO-1 pathway

AIM

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a free radical scavenger that has shown potent antioxidant, anti-inflammatory and neuroprotective effects in variety of disease models. In this study, we investigated whether edaravone produced neuroprotective actions in an infant mouse model of pneumococcal meningitis.

METHODS

C57BL/6 mice were infected on postnatal d 11 by intracisternal injection of a certain inoculum of Streptococcus pneumoniae. The mice received intracisternal injection of 10 μL of saline containing edaravone (3 mg/kg) once a day for 7 d. The severity of pneumococcal meningitis was assessed with a clinical score. In mice with severe meningitis, the survival rate from the time of infection to d 8 after infection was analyzed using Kaplan-Meier curves. In mice with mild meningitis, the CSF inflammation and cytokine levels in the hippocampus were analyzed d 7 after infection, and the clinical neurological deficit score was evaluated using a neurological scoring system d 14 after infection. The nuclear factor (erythroid-derived 2)-like 2 knockout (Nrf2 KO) mice and heme oxygenase-1 knockout (HO-1 KO) mice were used to confirm the involvement of Nrf2/HO-1 pathway in the neuroprotective actions of edaravone.

RESULTS

In mice with severe meningitis, edaravone treatment significantly increased the survival rate (76.4%) compared with the meningitis model group (32.2%). In mice with mild meningitis, edaravone treatment significantly decreased the number of leukocytes and TNF- levels in CSF, as well as the neuronal apoptosis and protein levels of HMGB1 and iNOS in the hippocampus, but did not affect the high levels of IL-10 and IL-6 in the hippocampus. Moreover, edaravone treatment significantly improved the neurological function of mice with mild meningitis. In Nrf2 KO or HO-1 KO mice with the meningitis, edaravone treatment was no longer effective in improving the survival rate of the mice with severe meningitis (20.2% and 53.6%, respectively), nor it affected the protein levels of HMGB1 and iNOS in the hippocampus of the mice with mild meningitis.

CONCLUSION

Edaravone produces neuroprotective actions in a mouse model of pneumococcal meningitis by reducing neuronal apoptosis and HMGB1 and iNOS expression in the hippocampus via the Nrf2/HO-1 pathway. Thus, edaravone may be a promising agent for the treatment of bacterial meningitis.

Bipolar Disorder: Role of Inflammation and the Development of Disease Biomarkers

Bipolar disorder is a severe and enduring psychiatric condition which in many cases starts during early adulthood and follows a relapsing and remitting course throughout life. In many patients the disease follows a progressive path with brief periods of inter-episode recovery, sub-threshold symptoms, treatment resistance and increasing functional impairment in the biopsychosocial domains. Knowledge about the neurobiology of bipolar disorder is increasing steadily and evidence from several lines of research implicates immuno-inflammatory mechanisms in the brain and periphery in the etiopathogenesis of this illness and its comorbidities. The main findings are an increase in the levels of proinflammatory cytokines during acute episodes with a decrease in neurotrophic support. Related to these factors are glial cell dysfunction, neuro-endocrine abnormalities and neurotransmitter aberrations which together cause plastic changes in the mood regulating areas of the brain and neuroprogression of the bipolar diathesis. Research in the above mentioned areas is providing an opportunity to discover novel biomarkers for the disease and the field is reaching a point where major breakthroughs can be expected in the not too distant future. It is hoped that with new discoveries fresh avenues will be found to better treat an otherwise recalcitrant disease.

Patterns of Local and Systemic Cytokines in Bacterial Meningitis and its Relation with Severity and Long-Term Sequelae

Bacterial meningitis (BM) is a pyogenic infection present in the subarachnoid space, potentially fatal and frequently associated with neurological sequelae. During BM, cytokines (CTs) are locally produced. We sought to determine the CTs' clinical role as disease severity predictors in adults, which is not completely clear. Using a bead-based flow cytometric assay, levels of six CTs were determined in cerebrospinal fluid (CSF) and plasma from 18 adult BM patients and 19 uninfected controls. Long-term neurological sequelae were evaluated using the Glasgow Outcome Scale (GOS). All evaluated CTs were higher in CSF than in plasma, and the levels of CSF interleukin (IL)-6, IL-8, IL-10, IL-1β, and tumor necrosis factor-α and plasma IL-10 and IL-12p70 were significantly higher in patients with severe sepsis than with sepsis, suggesting an association with clinical severity. There was a strong negative correlation between CSF IL-6 and plasma IL-12p70 with GOS score, supporting the possible role of these CTs in the development of neurological long-term sequelae. These findings could be helpful to identify candidates to receive neuroprotective treatments and early physiotherapy schemes.

Interleukin-6 in cerebrospinal fluid as a biomarker of acute meningitis

BACKGROUND

Microbiological culture of cerebrospinal fluid is the gold standard to differentiate between aseptic and bacterial meningitis, but this method has low sensitivity. A fast and reliable new marker would be of interest in clinical practice.

OBJECTIVE

Interleukin-6, secreted by T cells in response to meningeal pathogens and quickly delivered into cerebrospinal fluid, was evaluated as a marker of acute meningitis.

DESIGN AND METHODS

A total of 150 cerebrospinal fluid samples were analysed by an electrochemiluminescence method, selected according to patient diagnosis: (a) bacterial meningitis confirmed by positive culture (n = 26); (b) bacterial meningitis with negative culture or not performed (n = 15); (c) viral meningitis confirmed by polymerase chain reaction or immunoglobulin G determination (n = 23); (d) viral meningitis with polymerase chain reaction negative or not performed (n = 42); and (e) controls (n = 44).

RESULTS

Cerebrospinal fluid interleukin-6 concentration showed significant differences between all pathologic groups and the control group (P < 0.001). As a diagnostic tool for bacterial meningitis, interleukin-6 showed an area under the curve of 0.937 (95% confidence intervals: 0.895-0.978), significantly higher than those of classical biomarkers. An interleukin-6 cutoff of 1418 pg/mL showed 95.5% sensitivity and 77.5% specificity, whereas a value of 15,060 pg/mL showed 63.6% sensitivity and 96.7% specificity, for diagnosis of bacterial meningitis.

CONCLUSION

Interleukin-6 measured by electrochemiluminescence method is a promising marker for early differentiation between aseptic and bacterial meningitis. More studies are needed to validate clinical implications for future practice in an emergency laboratory.

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.