Central Nervous System Mycobacterium Infection: Tuberculosis and Beyond.

Tuberculosis is a contagious infectious disease caused by Mycobacterium tuberculosis, and is the leading cause of death from a single infectious agent worldwide. Imaging plays an important role in the early diagnosis of central nervous system tuberculosis and may prevent unnecessary morbidity and mortality. This article presents an extensive review of pathogenesis, clinical symptoms, typical and atypical imaging appearances of intracranial and spinal tuberculosis, and advanced imaging of intracranial tuberculosis. Furthermore, we explore central nervous system infection of nontuberculous mycobacteria and leprosy and their imaging findings.

Nos2-/- mice infected with M. tuberculosis develop neurobehavioral changes and immunopathology mimicking human central nervous system tuberculosis.

BACKGROUND: Understanding the pathophysiology of central nervous system tuberculosis (CNS-TB) is hampered by the lack of a good pre-clinical model that mirrors the human CNS-TB infection. We developed a murine CNS-TB model that demonstrates neurobehavioral changes with similar immunopathology with human CNS-TB. METHODS: We injected two Mycobacterium tuberculosis (M.tb) strains, H37Rv and CDC1551, respectively, into two mouse strains, C3HeB/FeJ and Nos2-/- mice, either into the third ventricle or intravenous. We compared the neurological symptoms, histopathological changes and levels of adhesion molecules, chemokines, and inflammatory cytokines in the brain induced by the infections through different routes in different strains. RESULTS: Intra-cerebroventricular infection of Nos2-/- mice with M.tb led to development of neurological signs and more severe brain granulomas compared to C3HeB/FeJ mice. Compared with CDC1551 M.tb, H37Rv M.tb infection resulted in a higher neurobehavioral score and earlier mortality. Intra-cerebroventricular infection caused necrotic neutrophil-dominated pyogranulomas in the brain relative to intravenous infection which resulted in disseminated granulomas and mycobacteraemia. Histologically, intra-cerebroventricular infection of Nos2-/- mice with M.tb resembled human CNS-TB brain biopsy specimens. H37Rv intra-cerebroventricular infected mice demonstrated higher brain concentrations of inflammatory cytokines, chemokines and adhesion molecule ICAM-1 than H37Rv intravenous-infected mice. CONCLUSIONS: Intra-cerebroventricular infection of Nos2-/- mice with H37Rv creates a murine CNS-TB model that resembled human CNS-TB immunopathology, exhibiting the worst neurobehavioral score with a high and early mortality reflecting disease severity and its associated neurological morbidity. Our murine CNS-TB model serves as a pre-clinical platform to dissect host-pathogen interactions and evaluate therapeutic agents for CNS-TB.

Correlation between CNS Tuberculosis and the COVID-19 Pandemic: The Neurological and Therapeutic Insights.

The recent outbreak of Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) from Wuhan, China, was caused by a single-stranded RNA virus which has kept the entire world stranded. The outbreak was first diagnosed with respiratory illness, but recent findings of acute necrotizing hemorrhage of brain, brain encephalopathy, and the presence of the virus in the cerebrospinal fluid (CSF) have unveiled its neuroinvasivness. Various clinical features related to the central nervous system (CNS) and peripheral nervous system (PNS) due to COVID-19 infection are now identified. We demonstrate here an apparent similarity in neurological disorders of COVID-19 with CNS tuberculosis, which suggests that some anti-tubercular drugs may be used as therapeutic agents against COVID-19 infection.

A Novel In Vitro Mouse Model to Study Mycobacterium tuberculosis Dissemination Across Brain Vessels: A Combination Granuloma and Blood-Brain Barrier Mouse Model.

In vitro culture models of the blood-brain barrier (BBB) provide a useful platform to test the mechanisms of cellular infiltration and pathogen dissemination into the central nervous system (CNS). We present an in vitro mouse model of the BBB to test Mycobacterium tuberculosis (Mtb) dissemination across brain endothelial cells. One-third of the global population is infected with Mtb, and in 1%-2% of cases bacteria invade the CNS through a largely unknown process. The "Trojan horse" theory supports the role of a cellular carrier that engulfs bacteria and carries them to the brain without being recognized. We present for the first time a protocol for an in vitro BBB-granuloma model that supports the Trojan horse mechanism of Mtb dissemination into the CNS. Handling of bacterial cultures, in vivo and in vitro infections, isolation of primary astroglial and endothelial cells, and assembly of the in vitro BBB model is presented. These techniques can be used to analyze the interaction of adaptive and innate immune system cells with brain endothelial cells, cellular transmigration, BBB morphological and functional changes, and methods of bacterial dissemination. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Isolation of primary mouse brain astrocytes and endothelial cells Basic Protocol 2: Isolation of primary mouse bone marrow-derived dendritic cells Support Protocol 1: Validation of dendritic cell purity by flow cytometry Basic Protocol 3: Isolation of primary mouse peripheral blood mononuclear cells Support Protocol 2: Isolation of primary mouse spleen cells Support Protocol 3: Purification and validation of CD4+ T cells from PBMCs and spleen cells Basic Protocol 4: Isolation of liver granuloma supernatant and determination of organ load Support Protocol 4: In vivo and in vitro infection with mycobacteria Basic Protocol 5: Assembly of the BBB co-culture model Basic Protocol 6: Assembly of the combined in vitro granuloma and BBB model.

Molecular and Histologic Diagnosis of Central Nervous System Infections.

Infections of the central nervous system cause significant morbidity and mortality in immunocompetent and immunocompromised individuals. A wide variety of microorganisms can cause infections, including bacteria, mycobacteria, fungi, viruses, and parasites. Although less invasive testing is preferred, surgical biopsy may be necessary to collect diagnostic tissue. Histologic findings, including special stains and immunohistochemistry, can provide a morphologic diagnosis in many cases, which can be further classified by molecular testing. Correlation of molecular, culture, and other laboratory results with histologic findings is essential for an accurate diagnosis, and to minimize false positives from microbial contamination.

Intensified adjunctive corticosteroid therapy for CNS tuberculomas.

INTRODUCTION: Central nervous system (CNS) tuberculomas are a challenging manifestation of extrapulmonary tuberculosis often leading to neurological complications and post-treatment sequelae. The role of adjunctive corticosteroid treatment is not fully understood. Most guidelines on management of tuberculosis do not distinguish between tuberculous meningitis and CNS tuberculomas in terms of corticosteroid therapy. METHODS: We describe five patients with CNS tuberculomas who required intensified dexamethasone treatment for several months, in two cases up to 18 months. RESULTS: These patients were initially treated with the standard four-drug tuberculosis regimen and adjuvant dexamethasone. Neurological symptoms improved rapidly. However, multiple attempts to reduce or discontinue corticosteroids according to guideline recommendations led to clinical deterioration with generalized seizures or new CNS lesions. Thus, duration of adjunctive corticosteroid therapy was extended eventually leading to clinical cure and resolution of lesions. CONCLUSION: In contrast to tuberculous meningitis, the treatment for CNS tuberculomas appears to require a prolonged administration of corticosteroids. These findings need to be verified in controlled clinical studies.

Primary Pituitary Tubercular Abscess: A Case Report.

Primary pituitary tubercular abscess is a very rare disease. It may present clinically with visual loss, headache, seizure, hormonal abnormalities or with cranial nerve palsies. MRI is the diagnostic modality and shows a cystic-solid mass in the sellar and suprasellar region, isointense on T1 and T2W images with heterogeneous areas and ring enhancement on contrast. Surgery remains the initial treatment and it is approached through the trans-sphenoidal/trans-nasal or transcranial route followed by anti-tubercular therapy. We report a case of primary pituitary tubercular abscess managed successfully with a brief review of its pathology. Keywords: abscess; pituitary gland; pyogenic; sella; tuberculosis.

Central nervous system tuberculosis reactivation following intravenous iron supplementation.

Patients with inflammatory bowel disease (IBD) are often treated with tumor necrosis factor (TNF)-alpha inhibitors and are therefore at higher risk for tuberculosis (TB) reactivation. IBD patients also frequently have iron deficiency which is often treated with intravenous iron supplementation. Iron plays an important role in mycobacterial infections, and reactivation of TB has been rarely reported after iron repletion. We present a case of a 63-year-old male with a history of Crohn's disease, on treatment with adalimumab for 2 years. The patient presented with malaise, mild lethargy, low-grade fever, and hyponatremia within a week after the first dose of intravenous iron. He was diagnosed with central nervous system TB (positive cerebrospinal fluid polymerase chain reaction and culture) and responded to treatment with a four-drug regimen. The timing of TB reactivation (within a week after intravenous iron administration) suggests that iron repletion contributed to the clinical reactivation of TB. Biological plausibility and prior similar clinical observations further support the causality of this association. Considering the frequency of iron deficiency in IBD, we believe that it is worthy to further explore the potential association between intravenous iron administration and the timing of TB reactivation in patients being treated with TNF-alpha inhibitors.

Outcomes of Pediatric Central Nervous System Tuberculosis in California, 1993-2011.

BACKGROUND: Our goal was to describe the characteristics and posttreatment outcomes of pediatric patients with central nervous system (CNS) tuberculosis (TB) and to identify factors associated with poor outcome. METHODS: We included children aged 0 to 18 years with CNS TB reported to the California TB registry between 1993 and 2011. Demographics, clinical characteristics, severity of disease at presentation (Modified Medical Research Council stage I, II, or III [III is most severe]), treatment, and outcomes during the year after treatment completion were abstracted systematically from the medical and public health records. Patient outcomes were categorized as good or poor on the basis of disability in hearing, vision, language, ambulation, and development and other neurologic deficits. RESULTS: Among 151 pediatric CNS TB cases reported between 1993 and 2011 in California for which records were available, 92 (61%) cases included sufficient information to determine outcome. Overall, 55 (60%) children had a poor outcome. After we adjusted for age (0 to 4 years), children with stage III severity (vs I or II; prevalence rate ratio [PRR], 1.4 [95% confidence interval (CI), 1.1-1.9]), a protein concentration of >100 mg/dL on initial lumbar puncture (PRR, 1.2 [95% CI, 1.03-1.4]), or infarct on neuroimaging (PRR, 1.2 [95% CI, 1.04-1.3]) were at increased risk for a poor outcome. In multivariate analysis, an age of 0 to 4 years (vs >4 years; PRR, 1.4 [95% CI, 1.2-1.7]) and a stage II or III Modified Medical Research Council score (vs stage I; PRR, 1.2 [95% CI, 1.03-1.5]) remained significantly associated with poor outcome. CONCLUSIONS: Pediatric patients with CNS TB in California are left with high rates of disabling clinical sequelae after treatment. The identification of modifiable factors is critical for improving outcomes.

Tuberculosis of the central nervous system in cattle in Paraíba, Brazil / Tuberculose no sistema nervoso central de bovinos na Paraíba

This paper describes six cases of tuberculosis in the central nervous system (CNS) of cattle in the state of Paraíba in northeastern Brazil. We reviewed the autopsy reports of 851 bovine necropsies performed from 2003 to 2016. Seventy-three (8.6%) cattle were diagnosed with tuberculosis and six showed lesions in the CNS. Three cases affected cattle up to two-year-old and other three affected adults. Three cattle presented exclusively nervous signs, two had respiratory signs and weight loss and one did not present any clinical signs. At necropsy, five cattle had thickening of the leptomeninges of the cerebellum, pons, obex, spinal cord and cortex, mainly, in the region near the brain basilar Willis´ circle. Another animal, presented a single focal lesion in the cerebellum. Microscopically we observed moderate to severe granulomatous meningitis and encephalitis. Five cattle presented lesions in the lungs and mediastinal lymph nodes and three of them had disseminated lesions in other organs. In all cattle acid-fast bacilli were observed in the lesions and marked positive for immunohistochemistry with polyclonal antibody anti-Mycobacterium tuberculosis. It is concluded that bovine tuberculosis of central nervous system occurs sporadically in Paraíba, in cattle of different ages, most of them with disseminate lesions in other organs. The location of the lesions suggests that the agent invaded the brain by hematogenous route through the circle of Willis.(AU)

Descrevem-se seis casos de tuberculose no sistema nervoso central (SNC) em bovinos, no semiárido da Paraíba. Foram revisados os laudos de um total de 851 necropsias de bovinos realizadas no período de 2003 a 2016. Destes, 73 (8,6%) foram diagnosticados com tuberculose e seis apresentavam lesões no SNC. Três casos ocorreram em bovinos de até dois anos de idade e três em bovinos adultos. Três bovinos apresentaram exclusivamente sinais nervosos, dois tinham sinais respiratórios e perda de peso e um não apresentava nenhum sinal clínico. Macroscopicamente, em cinco bovinos, havia espessamento das leptomeninges do cerebelo, medula espinhal, ponte, obex, colículos e córtex, principalmente, na região basilar encefálica próxima ao polígono de Willis. Em apenas um bovino houve a presença de tubérculo único no cerebelo. Microscopicamente observou-se moderada a acentuada meningite e encefalite granulomatosa. Cinco bovinos apresentaram lesões pulmonares e nos gânglios mediastínicos e três deles tinham lesões disseminadas em outros órgãos. Em todos os bovinos foram encontrados bacilos ácido-álcool resistentes intralesionais e todos tiveram marcação positiva na técnica de imuno-histoquímica com anticorpo policlonal anti-Mycobacterium tuberculosis. Conclui-se que a tuberculose do sistema nervoso central de bovinos ocorre de forma esporádica na Paraíba, principalmente em bovinos com lesões disseminadas em outros órgãos. Sugere-se que a disseminação do agente ocorre pela via hematógena, possivelmente através do polígono de Willis.(AU)

Human tuberculosis brain promotes neuronal apoptosis but not in astrocytes with high expression of vascular endothelial growth factor.

The present study aimed to investigate the involvement of the angiogenic marker vascular endothelia growth factor (VEGF) and apoptotic markers of Bcl-2 and Bax in the neurons and astrocytes in the brain infected by Mycobacterium tuberculosis. The immunohistochemistry staining was performed to analyze the expression of the VEGF, Bcl-2 and Bax in the astrocytes and neurons. The expression of VEGF was high in neurons and astrocytes in both the infected brain and control tissues with no difference of angiogenic activity (p = 0.40). Higher Bcl-2 expression was seen in astrocytes of infected brain tissues compared to the control tissues (p = 0.004) promoted a higher anti-apoptotic activity in astrocytes. The neurons expressed strong Bax expression in the infected brain tissues compared to the control tissues (p < 0.001), which indicated more apoptosis in neurons. Thus, neuronal death and survival of infected astrocytes together with high expression of VEGF might be associated with formation of brain tuberculosis. In conclusion, neurons could be more vulnerable than astrocytes in human tuberculosis brain with high expression of VEGF.

Tuberculosis of the central nervous system in children.

BACKGROUND: Central nervous system tuberculosis (CNS TB) in children is still a socioeconomic problem in developing countries. It has varied manifestations, symptoms are nonspecific, diagnosis can be challenging, and treatment may be difficult. It is often missed or overlooked. Among the various pathological entities, tuberculous meningitis is the most common and devastating manifestation. The resultant vasculitis, infarction, and hydrocephalus can be life-threatening. It can have grave cognitive, intellectual, and endocrine sequelae if not treated in time resulting in handicap, especially in resource constraint countries. Early diagnosis and treatment of tuberculous meningitis is the single most important factor determining outcome. Tuberculous hydrocephalus needs to be recognized early, and cerebrospinal fluid diversion procedure needs to be performed in adequate time to prevent morbidity or mortality in some cases. Tuberculous pachymeningitis and arachnoiditis are rare in children. Tuberculous abscess can mimic pyogenic abscess and requires high index of suspicion. Calvarial tuberculosis is seen in children and responds well to antituberculous chemotherapy. Drug-resistant tuberculosis is a formidable problem, and alternate chemotherapy should be promptly instituted. AIM: The pathogenesis, clinical features, diagnosis, and management of central nervous system tuberculosis in children are summarized. CONCLUSION: Heightened clinical suspicion, early diagnosis, appropriate antituberculous treatment, and surgery in relevant situation are essential for a gratifying outcome and preventing complications.

Complex regulation of neutrophil-derived MMP-9 secretion in central nervous system tuberculosis.

BACKGROUND: Central nervous system tuberculosis (CNS-TB) may be fatal even with treatment. Neutrophils are the key mediators of TB immunopathology, and raised CSF matrix metalloproteinase-9 (MMP-9) which correlates to neutrophil count in CNS-TB is associated with neurological deficit and death. The mechanisms by which neutrophils drive TB-associated CNS matrix destruction are not clearly defined. METHODS: Human brain biopsies with histologically proven CNS-TB were stained for neutrophils, neutrophil elastase, and MMP-9. Neutrophil MMP-9 secretion and gene expression were analyzed using Luminex and real-time PCR. Type IV collagen degradation was evaluated using confocal microscopy and quantitative fluorescent assays. Intracellular signaling pathways were investigated by immunoblotting and chemical inhibitors. RESULTS: MMP-9-expressing neutrophils were present in tuberculous granulomas in CNS-TB and neutrophil-derived MMP-9 secretion was upregulated by Mycobacterium tuberculosis (M.tb). Concurrent direct stimulation by M.tb and activation via monocyte-dependent networks had an additive effect on neutrophil MMP-9 secretion. Destruction of type IV collagen, a key component of the blood-brain barrier, was inhibited by neutralizing neutrophil MMP-9. Monocyte-neutrophil networks driving MMP-9 secretion in TB were regulated by MAP-kinase and Akt-PI3 kinase pathways and the transcription factor NF-kB. TNFα neutralization suppressed MMP-9 secretion to baseline while dexamethasone did not. CONCLUSIONS: Multiple signaling paths regulate neutrophil-derived MMP-9 secretion, which is increased in CNS-TB. These paths may be better targets for host-directed therapies than steroids currently used in CNS-TB.

Pregabalin-induced first degree atrioventricular block in a young patient treated for pain from extrapulmonary tuberculosis.

Pregabalin, widely used in the treatment of several pain disorders, is usually well tolerated. Uncommonly, the drug may induce cardiac side effects, rarely prolongation of the PR interval. The latter has never been described in patients with healthy heart or normal renal function. We characterize a unique case of a young man with extrapulmonary tuberculosis and no detectable or known cardiac or kidney diseases, treated with pregabalin to control the severe pain due to the involvement of the spinal cord by the tuberculosis, showing an atrioventricular (AV) block due to pregabalin administration. The reported case emphasizes the need of monitoring PR interval during treatment with pregabalin, even in patients without background of cardiac or renal diseases.

TNF-dependent regulation and activation of innate immune cells are essential for host protection against cerebral tuberculosis.

BACKGROUND: Tuberculosis (TB) affects one third of the global population, and TB of the central nervous system (CNS-TB) is the most severe form of tuberculosis which often associates with high mortality. The pro-inflammatory cytokine tumour necrosis factor (TNF) plays a critical role in the initial and long-term host immune protection against Mycobacterium tuberculosis (M. tuberculosis) which involves the activation of innate immune cells and structure maintenance of granulomas. However, the contribution of TNF, in particular neuron-derived TNF, in the control of cerebral M. tuberculosis infection and its protective immune responses in the CNS were not clear. METHODS: We generated neuron-specific TNF-deficient (NsTNF(-/-)) mice and compared outcomes of disease against TNF(f/f) control and global TNF(-/-) mice. Mycobacterial burden in brains, lungs and spleens were compared, and cerebral pathology and cellular contributions analysed by microscopy and flow cytometry after M. tuberculosis infection. Activation of innate immune cells was measured by flow cytometry and cell function assessed by cytokine and chemokine quantification using enzyme-linked immunosorbent assay (ELISA). RESULTS: Intracerebral M. tuberculosis infection of TNF(-/-) mice rendered animals highly susceptible, accompanied by uncontrolled bacilli replication and eventual mortality. In contrast, NsTNF(-/-) mice were resistant to infection and presented with a phenotype similar to that in TNF(f/f) control mice. Impaired immunity in TNF(-/-) mice was associated with altered cytokine and chemokine synthesis in the brain and characterised by a reduced number of activated innate immune cells. Brain pathology reflected enhanced inflammation dominated by neutrophil influx. CONCLUSION: Our data show that neuron-derived TNF has a limited role in immune responses, but overall TNF production is necessary for protective immunity against CNS-TB.