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

Detectability of cytokine and chemokine using ELISA, following sample-inactivation using Triton X-100 or heat

Clinical samples are routinely inactivated before molecular assays to prevent pathogen transmission. Antibody-based assays are sensitive to changes in analyte conformation, but the impact of inactivation on the analyte detectability has been overlooked. This study assessed the effects of commonly used inactivation-methods, Triton X-100 (0.5%) and heat (60 °C, 1 h), on cytokine/chemokine detection in plasma, lung aspirates, and nasopharyngeal samples. Heat significantly reduced analyte detectability in plasma (IL-12p40, IL-15, IL-16, VEGF, IL-7, TNF-β) by 33-99% (p ≤ 0.02), while Triton X-100 minimally affected analytes in plasma and nasopharyngeal samples (11-37%, p ≤ 0.04) and had no significant impact on lung aspirates. Structural analysis revealed that cytokines affected by heat had more hydrophobic residues and higher instability-indices. As the protein-detectability was affected differently in different sample types, the sample environment could also influence protein stability. This underscores the importance of selecting the most suitable inactivation methods for clinical samples to ensure accurate cytokine/chemokine analysis in both clinical and research settings.

Central Inflammatory Cytokines in Tuberculous Meningitis: A Systematic Review and Meta-analysis

No formal agreement exists regarding central inflammatory cytokine aberrations in tuberculosis (TB). We undertook a systematic review and meta-analysis of studies comparing cytokine levels in cerebrospinal fluid (CSF) from patients with TB compared with controls. We searched PubMed, Scopus, and Web of Science for articles published up to June 22, 2021. Studies were included in the meta-analysis if they assessed unadjusted levels of cytokines in unstimulated CSF samples and drew the comparison(s) between any of the following pairs: patients with TB versus controls without central nervous system (CNS) infection and meningitis, patients with TB versus patients with meningitis of etiologies other than Mycobacterium tuberculosis, HIV-infected patients with TB versus HIV-uninfected patients with TB, and HIV-infected patients with TB versus HIV-infected patients without TB. The primary outcome was the difference in mean CSF inflammatory cytokine levels between each of the 2 groups mentioned. The standardized mean difference was chosen to measure effect using a restricted maximum-likelihood estimator random-effects model. Of 1170 records identified, 40 studies were included in the meta-analysis. We calculated effect sizes for 30 different cytokines. About half of the studies took place in South Africa and India (18 out of 40 studies). Studies were mostly (92.5%) on patients with tuberculous meningitis (TBM), with only 3 articles of patients with neurotuberculosis and spinal TB. The quality of studies was rated as low to moderate and high with a 1.2:1 ratio. Compared with controls without CNS infection and meningitis, interferon-gamma (IFNγ), interleukin (IL)-12p40, IL-17F, IL-1β, IL-2, IL-4, IL-6, IL-8, sIL-2R, transforming growth factor beta (TGFβ), TGFβ1, and tumor necrosis factor alpha (TNFα) were increased in patients with TBM. Compared with patients with meningitis of etiologies other than M. tuberculosis or combined meningitis and nonmeningitis patients, patients with TBM had higher CSF concentrations of IFNγ, IL-13, and sIL-2R, whereas levels of IL-12p70, IL-15, IL-1Ra, IL-5, IL-7, IL-9, and sTNFR55 were decreased. Compared with patients with meningitis of bacterial etiologies other than M. tuberculosis, CSF levels of IFNγ and sIL-2R were increased in patients with TBM, whereas levels of IL-1Ra, IL-13, IL-17, and TNF R55-BP were decreased. Patients with TBM were not different from patients with CM for most CSF cytokines assessed, but IFNγ and IL-1β were increased. TNFα, IL-1β, IL-1Ra, IL-8, IFNγ, sIL-2R, IL-13, and IL-17 were higher in patients with TBM than those with viral or aseptic meningitis. Compared with HIV-negative patients with TBM, IFNγ, IL-10, IL-12p70, and IL-5 were decreased in HIV-positive patients with TBM, whereas IL-1β, TNFα, and IL-2 were increased. Elevated TNFα, IL-1β, IFNγ, IL-6, IL-17, and IFNα2 were found in HIV-positive patients with TBM compared with their counterparts without TBM. This study should be considered an explorative meta-analytic review, leading us to offer the best TBM-associated central inflammatory cytokines. Our study could prepare a panel of central cytokines as a potential aid in diagnosing TBM and its differentiation from meningitis of other etiologies.

Long-term Cognitive Outcomes in Tuberculous Meningitis

Objective

Data on cognitive changes in patients with tuberculous meningitis (TBM) are sparse. We aimed to study the cognitive profiles of patients with grade I TBM and correlate them with the cytokine values.

Methods

Prospectively, 60 patients (M:F-31:29) with grade I TBM were recruited. Clinical details were collected; CSF estimation of cytokines, neuropsychological assessment, and correlation were performed.

Results

Mean age at presentation was 32.2 years (32.2 ± 10.1), and the duration of symptoms was 29.9 days (29.9 ± 25.9), respectively. Definitive evidence of mycobacterial infection was observed in 28.3% of the patients. Mean levels of tumor necrosis factor-α (TNF-α), interferon (IFN-γ), and interleukin-6 (IL-6) were 11.57 ± 30.35, 197.02 ± 186.64, and 127.03 ± 88.71 pg/mL, respectively. TNF-α levels were significantly elevated in definitive TBM (p = 0.044). Neuropsychological tests revealed an impaired auditory verbal learning test (88.3%), followed by complex figure test (50%), spatial span test (50%), clock drawing test (48.3%), digit span test (35%), color trail tests 1 and 2 (30% and 33.3%, respectively), and animal naming test (28.3%). Elevated levels of IFN-γ and IL-6 in TBM directly correlated with the number of impaired neuropsychological tests. During follow-up, significant improvement was noticed in animal naming test (p = 0.005), clock drawing test (p = 0.003), color trail test 2 (0.02), spatial span test (p = 0.012), and digit span test (0.035). Verbal learning did not show any significant change. Overall, the neuropsychological tests showed better recovery of attention, working memory, and category fluency and showed minimal recovery of verbal learning.

Conclusions

There is subclinical evidence of cognitive impairment in patients with TBM, and this correlated with elevated cytokines. Both the frontal and temporal lobes showed varying degrees of cognitive impairment.

Serum and cerebrospinal fluid host proteins indicate stroke in children with tuberculous meningitis

Introduction

Stroke is a common complication in children with tuberculous meningitis (TBM). Host proteins may give us insight into the mechanisms of stroke in TBM and serve as biomarkers for detection of stroke, however, they have not been widely explored. In this study, we compared the concentrations of cerebrospinal fluid (CSF) and serum proteins between children who had TBM-related stroke and children with TBM without stroke.

Methods

We collected CSF and serum from 47 children consecutively admitted to the Tygerberg Academic Hospital in Cape Town, South Africa between November 2016, and November 2017, on suspicion of having TBM. A multiplex platform was used to measure the concentrations of 69 host proteins in CSF and serum from all study participants.

Results

After classification of study participants, 23 (48.9%) out of the 47 study participants were diagnosed with TBM, of which 14 (60.9%) demonstrated radiological arterial ischemic infarction. The levels of lipocalin-2, sRAGE, IP-10/ CXCL10, sVCAM-1, MMP-1, and PDGF-AA in CSF samples and the levels of D-dimer, ADAMTS13, SAA, ferritin, MCP-1/ CCL2, GDF-15 and IL-13 in serum samples were statistically different between children who had TBM-related stroke and children with TBM without stroke. After correcting for multiple testing, only the levels of sVCAM-1, MMP-1, sRAGE, and IP-10/ CXCL10 in CSF were statistically different between the two groups. CSF and serum protein biosignatures indicated stroke in children diagnosed with TBM with up to 100% sensitivity and 88.9% specificity.

Conclusion

Serum and CSF proteins may serve as biomarkers for identifying individuals with stroke amongst children diagnosed with TBM at admission and may guide us to understand the biology of stroke in TBM. This was a pilot study, and thus further investigations in larger studies are needed.

Tuberculous Meningitis: Pathogenesis, Immune Responses, Diagnostic Challenges, and the Potential of Biomarker-Based Approaches

Tuberculous meningitis (TBM) is the most devastating form of tuberculosis (TB), causing high mortality or disability. Clinical management of the disease is challenging due to limitations of the existing diagnostic approaches. Our knowledge on the immunology and pathogenesis of the disease is currently limited. More research is urgently needed to enhance our understanding of the immunopathogenesis of the disease and guide us toward the identification of targets that may be useful for vaccines or host-directed therapeutics.

Tuberculous meningitis (TBM) is the most devastating form of tuberculosis (TB), causing high mortality or disability. Clinical management of the disease is challenging due to limitations of the existing diagnostic approaches. Our knowledge on the immunology and pathogenesis of the disease is currently limited. More research is urgently needed to enhance our understanding of the immunopathogenesis of the disease and guide us toward the identification of targets that may be useful for vaccines or host-directed therapeutics. In this review, we summarize the current knowledge about the immunology and pathogenesis of TBM and summarize the literature on existing and new, especially biomarker-based, approaches that may be useful in the management of TBM. We identify research gaps and provide directions for research which may lead to the development of new tools for the control of the disease in the near future.

Host immune response to tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is a severe complication of tuberculosis predominantly affecting young children. Early treatment is vital to prevent morbidity and mortality, emphasizing the importance of early diagnosis. The lack of sensitive methods for early diagnosis is the most common cause of delay. Attempts have been made to develop simplified tests for tuberculosis, but their diagnostic power remains poor. The clinical picture of TBM is mainly driven by the host's immune response to Mycobacterium tuberculosis; therefore, identification of disease-specific biomarkers may have diagnostic and therapeutic value and improve our understanding of its pathogenesis.

METHODS

We investigated disease-specific biomarkers of childhood TBM in a cohort of children aged 3 months-13 years with symptoms and signs suggestive of meningitis. Cerebrospinal fluid (CSF) and serum from 56 patients with and 55 patients without TBM were assessed for 28 soluble mediators.

RESULTS

Unsupervised hierarchical clustering analysis revealed a disease-specific pattern of biomarkers for TBM relative to other types of meningitis. A biomarker-based diagnostic prediction model for childhood TBM based on CSF concentrations of interleukin 13 (cutoff value, 37.26 pg/mL), vascular endothelial growth factor (cutoff value, 42.92 pg/mL), and cathelicidin LL-37 (cutoff value, 3221.01 pg/mL) is presented with a sensitivity of 0.52 and a specificity of 0.95.

CONCLUSIONS

These data highlight the potential of biosignatures in the host's CSF for diagnostic applications and for improving our understanding of the pathogenesis of TBM to discover strategies to prevent immunopathological sequelae.

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

OBJECTIVE

We evaluated the levels of cerebrospinal fluid concentrations of tumor necrosis factor-α, interleukin-6, and interleukin-8 in bacterial meningitis in children.

METHODS

The study included children up to 14 years of age admitted to a pediatric ward with fever, headache, vomiting, and seizures. The diagnosis of bacterial meningitis was based on clinical features: physical examination, blood and cerebrospinal fluid cytochemical findings, Gram stain, and bacterial culture. The cerebrospinal fluid levels of tumor necrosis factor-α, interleukin-6, and interleukin-8 were measured in 57 children with bacterial meningitis, 15 with viral meningitis, and 15 controls by enzyme-linked immunosorbent assay methods.

RESULTS

The mean concentrations of cerebrospinal fluid, tumor necrosis factor-α, interleukin-6, and interleukin-8 were 1108 ± 183, 652 ± 287, and 442 ± 120 pg/mL, respectively, in children with bacterial meningitis and were significantly increased in those in the viral meningitis group (tumor necrosis factor-α : 711 ± 105, IL-6 : 272 ± 161, IL-8 : 175 ± 62 pg/mL; P < 0.001) or control (390 ± 37, 59 ± 17, 19 ± 13 pg/mL, respectively, P < 0.001). At optimum cutoff level based on the receiver operating characteristic curve, cerebrospinal fluid cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-8) showed sensitivity and specificity of 100% for the diagnosis of bacterial meningitis. For differentiation of bacterial from viral meningitis, cerebrospinal fluid level of tumor necrosis factor-α, IL-6, and IL-8 showed sensitivity and specificity of 94.7% and 86.7%, 80.7% and 53.3%, and 89.5% and 86.7%, respectively.

CONCLUSION

The increased concentration of cerebrospinal fluid tumor necrosis factor-α, interleukin-6, and interleukin-8 in children with meningitis suggests a role in the pathogenesis of bacterial meningitis and these levels might prove to be useful in children whose diagnosis is in question.

Comparison of cerebrospinal fluid in newborns and in infants ≤ 2 months old with or without meningitis

BACKGROUND

The aim of the present study was to evaluate the characteristics and accuracy of cerebrospinal fluid (CSF) parameters for neonatal meningitis, by comparing CSF data in newborns and in infants ≤ 2 months of age, with or without meningitis.

METHODS

This case-control study was performed on 120 newborns and infants ≤ 2 months old. 60 patients with meningitis were considered as the case group and 60 ill patients without meningitis were defined as the control group. Each of the two groups was divided into 0-1 months and 1-2 months old. CSF characteristics were compared in newborns in the case and control groups; in infants ≤ 2 months old in the case and control groups; and in healthy newborns and healthy infants ≤ 2 months old.

RESULTS

The mortality rate was 16.7% in the case group. The differences of CSF parameters in the case and control groups were mostly not significant, except for CSF glucose only in term newborns <7 days old (P= 0.04), and white cell count (WBC) only in 0-7-day-old term and preterm neonates (P= 0.04 and P= 0.01, respectively). Polymorphonuclear leukocyte (PMNL) level in the case group was significantly higher than in the control group (P= 0.02). CSF characteristics in healthy newborns were nearly the same as in healthy infants ≤ 2 months old. Prevalence of positive CSF culture was 31.7% in the case group. The most common pathogen was Neisseria meningitidis in the two age groups. The concomitant positive blood culture in the case group was 26.3%.

CONCLUSION

In the case of meningitis with negative CSF culture and Gram stain, diagnosis can be made on CSF parameters, clinical and laboratory findings and suspicion of meningitis. Therefore, a clinical prediction rule to classify risk for bacterial meningitis on evaluation of CSF parameters in any region should be established. More regional trials are needed to enhance the probability of diagnosis according to CSF parameters.

Prevention and treatment of nosocomial sepsis in the NICU

Nosocomial sepsis is a serious problem for neonates who are admitted for intensive care. It is associated with an increase in mortality, morbidity, and prolonged length of hospital stay. Thus, both the human and fiscal costs of these infections are high. Although the rate of nosocomial sepsis increases with the degree of both prematurity and low birth weight, no specific lab test has been shown to be very useful in improving our ability to predict who has a "real" blood-stream infection and, therefore, who needs to be treated with a full course of antibiotics. As a result, antibiotic use is double the rate of "proven" sepsis and we are facilitating the growth of resistant organisms in the neonatal intensive care unit. The purpose of this article is to describe simple changes in process, which when implemented, can reduce nosocomial infection rates in neonates and improve outcomes.

Invasion of the central nervous system by intracellular bacteria

Infection of the central nervous system (CNS) is a severe and frequently fatal event during the course of many diseases caused by microbes with predominantly intracellular life cycles. Examples of these include the facultative intracellular bacteria Listeria monocytogenes, Mycobacterium tuberculosis, and Brucella and Salmonella spp. and obligate intracellular microbes of the Rickettsiaceae family and Tropheryma whipplei. Unfortunately, the mechanisms used by intracellular bacterial pathogens to enter the CNS are less well known than those used by bacterial pathogens with an extracellular life cycle. The goal of this review is to elaborate on the means by which intracellular bacterial pathogens establish infection within the CNS. This review encompasses the clinical and pathological findings that pertain to the CNS infection in humans and includes experimental data from animal models that illuminate how these microbes enter the CNS. Recent experimental data showing that L. monocytogenes can invade the CNS by more than one mechanism make it a useful model for discussing the various routes for neuroinvasion used by intracellular bacterial pathogens.