Diagnostic Usefulness of Cytokine and Chemokine Levels in the Cerebrospinal Fluid of Patients with Suspected Tuberculous Meningitis

Systemic and cerebrospinal fluid biomarkers for tuberculous meningitis identification and treatment monitoring

IMPORTANCE

Tuberculous meningitis is a life-threatening infection with high mortality and disability rates. Current diagnostic methods using cerebrospinal fluid (CSF) samples have limited sensitivity and lack predictive biomarkers for evaluating prognosis. This study's findings reveal excessive activation of the immune response during tuberculous meningitis (TBM) infection. Notably, a strong negative correlation was observed between CSF levels of monokine induced by interferon-γ (MIG) and the CSF/blood glucose ratio in TBM patients. MIG also exhibited the highest area under the curve with high sensitivity and specificity. This study suggests that MIG may serve as a novel biomarker for differentiating TBM infection in CSF or serum, potentially leading to improved diagnostic accuracy and better patient outcomes.

Recent advances in understanding the human host immune response in tuberculous meningitis

Tuberculous meningitis (TBM), the most severe form of tuberculosis, causes death in approximately 25% cases despite antibiotic therapy, and half of survivors are left with neurological disability. Mortality and morbidity are contributed to by a dysregulated immune response, and adjunctive host-directed therapies are required to modulate this response and improve outcomes. Developing such therapies relies on improved understanding of the host immune response to TBM. The historical challenges in TBM research of limited in vivo and in vitro models have been partially overcome by recent developments in proteomics, transcriptomics, and metabolomics, and the use of these technologies in nested substudies of large clinical trials. We review the current understanding of the human immune response in TBM. We begin with M. tuberculosis entry into the central nervous system (CNS), microglial infection and blood-brain and other CNS barrier dysfunction. We then outline the innate response, including the early cytokine response, role of canonical and non-canonical inflammasomes, eicosanoids and specialised pro-resolving mediators. Next, we review the adaptive response including T cells, microRNAs and B cells, followed by the role of the glutamate-GABA neurotransmitter cycle and the tryptophan pathway. We discuss host genetic immune factors, differences between adults and children, paradoxical reaction, and the impact of HIV-1 co-infection including immune reconstitution inflammatory syndrome. Promising immunomodulatory therapies, research gaps, ongoing challenges and future paths are discussed.

Development and validation of a new model for the early diagnosis of tuberculous meningitis in adults based on simple clinical and laboratory parameters

BACKGROUND

The differential diagnosis between tuberculous meningitis (TBM) and viral meningitis (VM) or bacterial meningitis (BM) remains challenging in clinical practice, particularly in resource-limited settings. This study aimed to establish a diagnostic model that can accurately and early distinguish TBM from both VM and BM in adults based on simple clinical and laboratory parameters.

METHODS

Patients diagnosed with TBM or non-TBM (VM or BM) between January 2012 and October 2021 were retrospectively enrolled from the General Hospital (derivation cohort) and Branch Hospital (validation cohort) of Ningxia Medical University. Demographic characteristics, clinical symptoms, concomitant diseases, and cerebrospinal fluid (CSF) parameters were collated. Univariable logistic analysis was performed in the derivation cohort to identify significant variables (P < 0.05). A multivariable logistic regression model was constructed using these variables. We verified the performance including discrimination, calibration, and applicability of the model in both derivation and validation cohorts.

RESULTS

A total of 222 patients (70 TBM and 152 non-TBM [75 BM and 77 VM]) and 100 patients (32 TBM and 68 non-TBM [31 BM and 37 VM]) were enrolled as derivation and validation cohorts, respectively. The multivariable logistic regression model showed that disturbance of consciousness for > 5 days, weight loss > 5% of the original weight within 6 months, CSF lymphocyte ratio > 50%, CSF glucose concentration < 2.2 mmol/L, and secondary cerebral infarction were independently correlated with the diagnosis of TBM (P < 0.05). The nomogram model showed excellent discrimination (area under the curve 0.959 vs. 0.962) and great calibration (P-value in the Hosmer-Lemeshow test 0.128 vs. 0.863) in both derivation and validation cohorts. Clinical decision curve analysis showed that the model had good applicability in clinical practice and may benefit the entire population.

CONCLUSIONS

This multivariable diagnostic model may help clinicians in the early discrimination of TBM from VM and BM in adults based on simple clinical and laboratory parameters.

Adenosine deaminase from the cerebrospinal fluid for the diagnosis of tuberculous meningitis: A meta-analysis

OBJECTIVE

To comprehensively evaluate the diagnostic efficacy of adenosine deaminase in cerebrospinal fluid (CSF) for tuberculous meningitis (TBM), and the potential influence of patients' age groups and cutoffs of measured adenosine deaminase.

METHODS

Systematic review and meta-analysis of relevant studies retrieved from PubMed, Embase, and Web of Science databases. Pooled sensitivity and specificity were calculated with a random-effect model.

RESULTS

Overall, 43 studies with 1653 patients with TBM and 3417 controls without were included. Pooled results showed that adenosine deaminase in CSF is associated with satisfactory diagnostic efficacy for TBM, with a pooled sensitivity of 0.86 (95% confidence interval [CI]: 0.82-0.90), specificity of 0.89 (95% CI: 0.86-0.91), positive likelihood ratio of 7.70 (95% CI: 6.16-9.63), and negative likelihood ratio of 0.15 (95% CI: 0.12-0.20). The pooled receiver operating characteristic (AUC) was 0.94 (95% CI: 0.91-0.96), suggesting good performance. Subgroup analyses showed good diagnostic efficacies of adenosine deaminase in CSF for both adults (AUC 0.95) and children (AUC 0.96) with TBM. AUCs indicating the diagnostic accuracies of adenosine deaminase in CSF for TBM were 0.93 for studies with cutoffs <10 U/L and and 0.94 for a cutoff =10 U/L, but only 0.90 for studies with cutoffs >10 U/L.

CONCLUSIONS

Measuring adenosine deaminase of CSF shows satisfactory diagnostic efficacy for TBM in children and adults, particularly if using a cutoff ≤10 U/L.

Increased peripheral inflammatory responses in myelin oligodendrocyte glycoprotein associated disease and aquaporin-4 antibody positive neuromyelitis optica spectrum disorder

Autoantibody-associated demyelinating diseases of the central nervous system such as myelin oligodendrocyte glycoprotein-antibody associated disease (MOGAD) and aquaporin 4-antibody positive neuromyelitis optica spectrum disorders (AQP4+ NMOSD) are rare diseases but can cause severe disability. In both diseases, associated neuroinflammation is accompanied by blood and cerebrospinal fluid cytokine and chemokine signatures, which were shown to be distinct from those observed in patients with multiple sclerosis (MS). In this study, we aimed to confirm and extend these findings by analyzing a larger number of serum cytokines, chemokines and related molecules in patients with MOGAD or AQP4+ NMOSD in comparison to MS, to better understand the pathophysiology and to identify biomarkers potentially useful in clinical practice for diagnostic and treatment purposes. A total of 65 serum cytokines, chemokines and related molecules like growth factors and soluble receptors were measured by Procartaplex multiplex immunoassays in 40 MOGAD, 40 AQP4+ NMOSD and 54 MS patients at baseline. Furthermore, follow-up samples of 25 AQP4+ NMOSD and 40 MOGAD patients were measured after 6-12 months. Selected analytes were validated in a subgroup of samples using other bead-based assays and ELISA. At baseline, 36 analytes in MOGAD and 30 in AQP4+ NMOSD were significantly increased compared to MS. K-means cluster analysis of all significantly altered molecules revealed three distinct groups: Cluster I, including 12 MOGAD, 2 AQP4+ NMOSD and 3 MS patients, had a specific association with 11 IL-6/IL-17A associated cytokines. In this cluster, 9/17 (53%) patients were children. Cluster II with 13 MOGAD, 24 AQP4+ NMOSD and 1 MS patient was associated with 31 upregulated analytes. Cluster III contained 15 MOGAD, 14 AQP4+ NMOSD and 50 MS patients. In cluster II and III the majority were adults (82% and 92%). Most measured analytes remained stable over time. Validation of selected cytokines and chemokines using other analytical methods revealed moderate to high correlation coefficients, but absolute values differed between assays. In conclusion, these results obtained by bead-based multiplex assays highlight a significant association of biomarkers of peripheral inflammation in patients with antibody-associated demyelinating diseases in comparison with MS.

Tuberculosis-specific antigen stimulated and unstimulated interferon-γ for tuberculous meningitis diagnosis: A systematic review and meta-analysis

Objective

Tuberculous meningitis (TBM) is one of the most devastating TB. Accurate identification of TBM is helpful to eliminate TB. Therefore, we assessed the performance of TBAg stimulated IFN-γ (IGRA) and unstimulated IFN-γ in blood and cerebrospinal fluid (CSF) for diagnosing TBM.

Methods

We searched Web of Science, PubMed, Embase and the Cochrane Library databases until March 2022. Bivariate and hierarchical summary receiver operating characteristic models were employed to compute summary estimates for diagnostic accuracy parameters of IGRA and unstimulated IFN-γ in blood and CSF for diagnosing TBM.

Results

28 studies including 1,978 participants and 2,641 samples met the inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUROC) of blood IGRA were separately as 0.73, 0.83, 4.32, 0.33, 13.22 and 0.86, indicating a good diagnostic accuracy of blood IGRA for detecting TBM. The summary sensitivity, specificity, PLR, NLR, DOR and AUROC of CSF IGRA were separately as 0.77, 0.91, 8.82, 0.25, 34.59 and 0.93, indicating good diagnostic accuracy of CSF IGRA for detecting TBM. The summary sensitivity, specificity, PLR, NLR, DOR and AUROC of CSF IFN-γ were separately as 0.86, 0.92, 10.27, 0.16, 65.26 and 0.95, suggesting CSF IFN-γ provided excellent accuracy for diagnosing TBM.

Conclusions

For differentiating TBM from non-TBM individuals, blood and CSF IGRA are good assays and unstimulated CSF IFN-γ is an auxiliary excellent marker.

Improving Technology to Diagnose Tuberculous Meningitis: Are We There Yet?

Diagnosis of tuberculous meningitis (TBM) remains challenging due to a paucity of high-performance diagnostics. Even those that have reasonable sensitivity are not adequate to 'rule out' TBM. Therefore, a combination of clinical factors alongside microbiological, molecular, and radiological investigations are utilized, depending on availability. A low threshold for starting empiric therapy in the appropriate clinical scenario remains crucial for good outcomes in many cases. Herein, we review the current TBM diagnostics landscape with a focus on limitations frequently encountered, such as diagnostic test performance, cost, laboratory infrastructure, and clinical expertise. Though molecular technologies, particularly GeneXpert MTB/Rif Ultra, have been a step forward, diagnosis of TBM remains difficult. We also provide an overview of promising technologies, such as cerebrospinal fluid (CSF) lactate, a new lipoarabinomannan test (FujiLAM), metagenomic next-generation sequencing, and transcriptomics that may further improve our TBM diagnostic capacity and lead to better outcomes.

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.

Diagnostic Model for Discrimination Between Tuberculous Meningitis and Bacterial Meningitis

Background

The differential diagnosis between tuberculous meningitis (TBM) and bacterial meningitis (BM) remains challenging in clinical practice. This study aimed to establish a diagnostic model that could accurately distinguish TBM from BM.

Methods

Patients with TBM or BM were recruited between January 2017 and January 2021 at Tongji Hospital (Qiaokou cohort) and Sino-French New City Hospital (Caidian cohort). The detection for indicators involved in cerebrospinal fluid (CSF) and T-SPOT assay were performed simultaneously. Multivariate logistic regression was used to create a diagnostic model.

Results

A total of 174 patients (76 TBM and 98 BM) and another 105 cases (39 TBM and 66 BM) were enrolled from Qiaokou cohort and Caidian cohort, respectively. Significantly higher level of CSF lymphocyte proportion while significantly lower levels of CSF chlorine, nucleated cell count, and neutrophil proportion were observed in TBM group when comparing with those in BM group. However, receiver operating characteristic (ROC) curve analysis showed that the areas under the ROC curve (AUCs) produced by these indicators were all under 0.8. Meanwhile, tuberculosis-specific antigen/phytohemagglutinin (TBAg/PHA) ratio yielded an AUC of 0.889 (95% CI, 0.840–0.938) in distinguishing TBM from BM, with a sensitivity of 68.42% (95% CI, 57.30%–77.77%) and a specificity of 92.86% (95% CI, 85.98%–96.50%) when a cutoff value of 0.163 was used. Consequently, we successfully established a diagnostic model based on the combination of TBAg/PHA ratio, CSF chlorine, CSF nucleated cell count, and CSF lymphocyte proportion for discrimination between TBM and BM. The established model showed good performance in differentiating TBM from BM (AUC: 0.949; 95% CI, 0.921–0.978), with 81.58% (95% CI, 71.42%–88.70%) sensitivity and 91.84% (95% CI, 84.71%–95.81%) specificity. The performance of the diagnostic model obtained in Qiaokou cohort was further validated in Caidian cohort. The diagnostic model in Caidian cohort produced an AUC of 0.923 (95% CI, 0.867–0.980) with 79.49% (95% CI, 64.47%–89.22%) sensitivity and 90.91% (95% CI, 81.55%–95.77%) specificity.

Conclusions

The diagnostic model established based on the combination of four indicators had excellent utility in the discrimination between TBM and BM.

Neurologic Complications of Tuberculosis

PURPOSE OF REVIEW

This article describes the current epidemiology, common clinical characteristics, and up-to-date evidence-based approaches to the diagnosis and management of the most common neurologic complications of tuberculosis (TB): tuberculous meningitis, intracranial tuberculoma, and spinal TB.

RECENT FINDINGS

Central nervous system (CNS) TB remains common and associated with significant mortality and neurologic sequelae worldwide. Human immunodeficiency virus (HIV) co-infection is strongly associated with both the development of and mortality due to CNS TB. Strongyloides co-infection is associated with reduced CNS inflammation and improved outcomes in the setting of tuberculous meningitis. Stroke remains a common complication of tuberculous meningitis, and emerging evidence suggests aspirin may be used in this context. Although a recent nucleic acid amplification test has demonstrated suboptimal sensitivity in the diagnosis of CNS TB, emerging diagnostic techniques include cell-free DNA, peripheral blood microRNA, metagenomic next-generation sequencing, and advanced imaging techniques, but these are not yet well validated. CNS TB is associated with high mortality even with current treatment regimens, although novel, promising strategies for treatment are under investigation, including a combination of IV isoniazid and ethambutol and high-dose rifampicin.

SUMMARY

TB can affect the nervous system in various ways and is associated with high mortality. Diagnosis remains challenging in endemic settings, with empiric treatment often initiated without a definitive diagnosis. Furthermore, optimal treatment regimens remain uncertain because current treatment for all forms of CNS TB is extrapolated from trials of tuberculous meningitis whereas the role of steroids in people with HIV and tuberculous meningitis remains controversial.

Differences in cytokine and chemokine profiles in cerebrospinal fluid caused by the etiology of cryptococcal meningitis and tuberculous meningitis in HIV patients

The roles of cytokines and chemokines in HIV-associated cryptococcal meningitis (HCM) and HIV-associated tuberculous meningitis (HTBM) are debatable. In sum, 34 HIV-infected patients without meningitis, 44 HCM patients and 27 HTBM patients were enrolled for study. The concentrations of 22 cytokines/chemokines in cerebrospinal fluid (CSF) were assayed at admission. Principal component analysis (PCA), Pearson's and logistic regression analyses were used to assess the role of cytokines/chemokines in HCM and HTBM. We found the levels of T helper (Th)17, Th1 [interleukin (IL)-12p40, interferon (IFN)-γ, tumor necrosis factor (TNF)-α and TNF-β and Th2 (IL-2/4/5/6/10)] cytokines were elevated in patients with meningitis compared with those in HIV-infected patients without central nervous system (CNS) infection. Furthermore, the IL-1Ra, IL-12p40, IL-17α and monocyte chemotactic protein-1 (MCP-1) levels were higher in HCM patients, while the IFN-γ, regulated upon activation, normal T cell expressed and secreted (RANTES) and interferon-inducible protein-10 (IP)-10 levels were higher in HTBM patients. Elevated CSF concentrations of IL-17a, TNF-β, IL-5, IL-12p40 and IL-1Rα were closely related to meningitis, but elevated IP-10, MCP-1, RANTES and IFN-γ levels and CSF white blood cells (WBCs) were protective factors against HCM. Our study suggested that HIV-infected patients with low CSF WBCs have a high risk of HCM. Th1, Th2 and Th17 cytokines/chemokines mediate differences in the pathogenesis of HCM and TBM. Overexpressed proinflammatory MCP-1, RANTES, IFN-γ and IP-10 in CSF are protective factors against HCM but not HTBM.

Diagnostic Accuracy of T-SPOT.TB Assay for Tuberculous Meningitis: An Updated Meta-Analysis

Background: The role of T-SPOT.TB (T-SPOT) assay for tuberculous meningitis (TBM) diagnosis has not been fully assessed. Here, we conducted an updated meta-analysis to evaluate the diagnostic accuracy of peripheral blood (PB) T-SPOT and cerebrospinal fluid (CSF) T-SPOT for diagnosing TBM. Methods: Relevant studies in the PubMed database, EmBase database, Cochrane database, Scopus database, Google Scholar, China National Knowledge Internet, and Wan-Fang database were retrieved from August 1, 2005, to June 22, 2020. Statistical analysis was performed using Stata, Revman, and Meta-Disc software. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), summary receiver operating characteristic curves, and the area under the curve were determined and analyzed. Results: A total of 27 studies were eligible for inclusion within the meta-analysis. The pooled sensitivity and specificity of PB T-SPOT for TBM diagnosis were 0.78 (95% CI, 0.76-0.81) and 0.68 (95% CI, 0.66-0.71), respectively, whereas the pooled PLR, NLR, and DOR were 2.80 (95% CI, 2.29-3.42), 0.32 (95% CI, 0.27-0.38), and 10.08 (95% CI, 7.21-14.08), respectively. On the other hand, the pooled sensitivity and specificity of CSF T-SPOT on diagnosing TBM were 0.76 (95% CI, 0.72-0.80) and 0.88 (95% CI, 0.85-0.90), respectively, whereas the pooled PLR, NLR, and DOR were 5.92 (95% CI, 4.25-8.25), 0.28 (95% CI, 0.21-0.39), and 29.05 (95% CI, 16.40-51.45), respectively. The area under the summary receiver operating characteristic curve values of PB T-SPOT and CSF T-SPOT for TBM diagnosis were 0.83 (95% CI, 0.80-0.86) and 0.92 (95% CI, 0.89-0.94), respectively. Conclusions: CSF T-SPOT showed a higher specificity compared with PB T-SPOT for diagnosing TBM. Both two T-SPOT assays have considerable potential in improving the diagnosis of TBM. Furthermore, the standardization of the operating procedure is further needed when performing CSF T-SPOT.