HMGB1 level in cerebrospinal fluid as a complimentary biomarker for the diagnosis of tuberculous meningitis

Diagnosis of extra pulmonary tuberculosis: An update on novel diagnostic approaches

Tuberculosis (TB) remains a major global public health problem worldwide. Though Pulmonary TB (PTB) is mostly discussed, one in five cases of TB present are extrapulmonary TB (EPTB) that manifests conspicuous diagnostic and management challenges with respect to the site of infection. The diagnosis of EPTB is often delayed or even missed due to insidious clinical presentation, pauci-bacillary nature of the disease, and lack of laboratory facilities in the resource limited settings. Culture, the classical gold standard for the diagnosis of tuberculosis, suffers from increased technical and logistical constraints in EPTB cases. Other than culture, several other tests are available but their feasibility and effciacy for the detection of EPTB is still the matter of interest. We need more specific and precise test/s for the various forms of EPTB diagnosis which can easily be applied in the routine TB control program is required. A test that can contribute remarkably towards improving EPTB case detection reducing the morbidity and mortality is the utmost requirement. In this review we described the scenario of molecular and other noval methods available for laboratory diagnosis of EPTB, and also discussed the challenges linked with each diagnostic method. This review will make the readers aware of new emerging diagnostic techniques in the field of EPTB diagnosis. They can make an informed decision to choose the appropriate one according to the test availability, their clinical settings and financial considerations.

Potential significance of high-mobility group protein box 1 in cerebrospinal fluid

High-mobility group protein box 1 (HMGB1) is a cytokine with multiple functions (according to its subcellular location) that serves a marker of inflammation. CSF HMGB1 could be the part of pathological mechanisms that underlie the complications associated with CNS diseases. HMGB1 actively or passively released into the CSF is detected in the CSF in many diseases of the central nervous system (CNS) and thus may be useful as a biomarker. Pathological alterations in distant areas were observed due to lesions in a specific region, and the level of HMGB1 in the CSF was found to be elevated. Reducing the HMGB1 level via intraventricular injection of anti-HMGB1 neutralizing antibodies can improve the outcomes of CNS diseases. The results indicated that CSF HMGB1 could serve as a biomarker for predicting disease progression and may also act as a pathogenic factor contributing to pathological alterations in distant areas following focal lesions in the CNS. In this mini-review, the characteristics of HMGB1 and progress in research on CSF HMGB1 as a biomarker of CNS diseases were discussed. CSF HMGB1 is useful not only as a biomarker of CNS diseases but may also be involved in interactions between different brain regions and the spinal cord.

Validation of host cerebrospinal fluid protein biomarkers for early diagnosis of tuberculous meningitis in children: a replication and new biosignature discovery study

The diagnosis of tuberculous meningitis (TBM) in children is often delayed due to diagnostic difficulties. New tools are urgently needed to improve the diagnosis of the disease in this vulnerable group. The present study aimed to validate the accuracy of recently identified host cerebrospinal (CSF) biomarkers as candidates for the diagnosis of TBM in children. We collected CSF samples from 87 children aged 3 months to 13 years, that were consecutively admitted at a tertiary hospital in Cape Town, South Africa, on suspicion of having TBM. We evaluated the concentrations of 67 selected host protein biomarkers using a multiplex platform. Previously identified 3-marker (VEGF-A + IFN-γ + MPO) and 4-marker (IFN-γ + MPO + ICAM-1 + IL-8) signatures diagnosed TBM with AUCs of 0.89 (95% CI, 0.81-0.97) and 0.87 (95% CI, 0.79-0.95) respectively; sensitivities of 80.6% (95% CI, 62.5-92.5%) and 81.6% (95% CI, 65.7-92.3%), and specificities of 86.8% (71.9-95.6%) and 83.7% (70.4-92.7%) respectively. Furthermore, a new combination between the analytes (CC4b + CC4 + procalcitonin + CCL1) showed promise, with an AUC of 0.98 (95% CI, 0.94-1.00). We have shown that the accuracies of previously identified candidate CSF biomarkers for childhood TBM was reproducible. Our findings augur well for the future development of a simple bedside test for the rapid diagnosis of TBM in children.

Anti-HMGB1 antibody is a potential characteristic autoantibody for Sjögren's syndrome

Sjögren's syndrome (SS) is a common chronic inflammatory autoimmune disease that affects about 0.33–0.77% population in China. The positive for antinuclear antibodies (ANA) is one of the key features of SS, which shows a nuclear fine speckled (AC-4) pattern in an indirect immunofluorescent antibody test (IIFT). About 70% of ANA-positive SS patients have detectable anti-SS-A and/or SS-B antibodies, which indicates that other autoantibodies may present in SS patients. The anti-HMGB1 antibodies in 93 SS patients and 96 healthy controls were investigated with in-house developed ELISA and immunoblotting, and the locations of HMGB1 and fluorescent pattern of anti-HMGB1 antibody were investigated with IIFT. The contribution of anti-HMGB1 antibody in ANA-IF was evaluated with Cas9-induce HMGB1 knockout B16 cells. The anti-HMGB1 antibody level is higher in SS patients (9.96 ± 5.55 RU/ml) than in healthy controls (4.9 ± 1.4 RU/ml). With ROC curve analysis, when taking 8 RU/ml as the cutoff value, the sensitivity, specificity, and the area under the curve were 64.5%, 96.9%, and 0.83, respectively. A total of 18 patients (20.7%) with nuclear fine speckled (AC-4) pattern in ANA-IF test were anti-HMGB1 antibody positive only. With commercial antibody, anti-HMGB1 antibody showed the same nuclear fine speckled (AC-4) pattern. The serum from ANA-IF (+), SS-A (−), and SS-B (−) SS patients showed nuclear fine speckled (AC-4) pattern in wildtype B16 cells, but no fluorescence in HMGB1 knockout B16 cells. Anti-HMGB1 antibody may be one of the characteristic autoantibodies of SS in addition to anti-SS-A and SS-B. The detection of anti-HMGB1 antibody can provide more laboratory evidence for clinical diagnosis of SS.

HMGB1, anti-HMGB1 antibodies, and ratio of HMGB1/anti-HMGB1 antibodies as diagnosis indicator in fever of unknown origin

To evaluate the feasibility of serum HMGB1, anti-HMGB1 antibodies, and HMGB1/anti-HMGB1 ratio as a diagnosis indicator of initial clinical classification in patients with fever of unknown origin (FUO). Ninety-four patients with classical FUO and ninety healthy controls were enrolled in this study. The subjects’ clinical data and serum were collected. The serum concentration of HMGB1 was detected by a commercial HMGB1 ELISA kit, while the serum concentration of anti-HMGB1 antibodies were detected by an in-house built anti-HMGB1 antibodies ELISA kit and further confirmed by immunoblotting. According to the hospital diagnosis on discharge, ninety-four FUO patients were divided into four groups, Infectious disease subgroup, autoimmune disease subgroup, malignant tumor subgroup, and undetermined subgroup. The concentrations of HMGB1 in the infectious disease subgroup and autoimmune disease subgroup were higher than those in the malignant tumor subgroup, undetermined subgroup, and healthy control group. The concentration of anti-HMGB1 antibodies in autoimmune disease subtype group was higher than those in other subgroups as well as healthy control group. According to the distribution of HMGB1 and anti-HMGB1 in scatter plots of the patients with FUO, we found that the ratio of serum HMGB1/anti-HMGB1 is an ideal clinical indicator for differential diagnosis of different subtypes of FUO. The best cut-off was 0.75, and the sensitivity, specificity, and AUC were 66.67%, 87.32%, and 0.8, respectively. Correlation analysis showed that serum concentration of HMGB1 was moderately correlated with CRP in infectious diseases subgroup, and the serum concentration of anti-HMGB1 antibodies was strongly correlated with erythrocyte sedimentation rate in autoimmune disease subgroup. Our study had showed that serum HMGB1/anti-HMGB1 antibodies ratio can help clinicians identify FUO subtypes, thereby avoiding many unnecessary examinations and tests, and improving the effectiveness of clinical diagnosis and treatment of FUO.

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.

The pathogenesis of tuberculous meningitis

Tuberculosis (TB) remains a leading cause of death globally. Dissemination of TB to the brain results in the most severe form of extrapulmonary TB, tuberculous meningitis (TBM), which represents a medical emergency associated with high rates of mortality and disability. Via various mechanisms the Mycobacterium tuberculosis (M.tb) bacillus disseminates from the primary site of infection and overcomes protective barriers to enter the CNS. There it induces an inflammatory response involving both the peripheral and resident immune cells, which initiates a cascade of pathologic mechanisms that may either contain the disease or result in significant brain injury. Here we review the steps from primary infection to cerebral disease, factors that contribute to the virulence of the organism and the vulnerability of the host and discuss the immune response and the clinical manifestations arising. Priorities for future research directions are suggested.