Neisseria meningitidis activates pyroptotic pathways in a mouse model of meningitis: role of a two-partner secretion system.

There is evidence that in infected cells in vitro the meningococcal HrpA/HrpB two-partner secretion system (TPS) mediates the exit of bacteria from the internalization vacuole and the docking of bacteria to the dynein motor resulting in the induction of pyroptosis. In this study we set out to study the role of the HrpA/HrpB TPS in establishing meningitis and activating pyroptotic pathways in an animal model of meningitis using a reference serogroup C meningococcal strain, 93/4286, and an isogenic hrpB knockout mutant, 93/4286ΩhrpB. Survival experiments confirmed the role of HrpA/HrpB TPS in the invasive meningococcal disease. In fact, the ability of the hrpB mutant to replicate in brain and spread systemically was impaired in mice infected with hrpB mutant. Furthermore, western blot analysis of brain samples during the infection demonstrated that: i. N. meningitidis activated canonical and non-canonical inflammasome pyroptosis pathways in the mouse brain; ii. the activation of caspase-11, caspase-1, and gasdermin-D was markedly reduced in the hrpB mutant; iii. the increase in the amount of IL-1ß and IL-18, which are an important end point of pyroptosis, occurs in the brains of mice infected with the wild-type strain 93/4286 and is strongly reduced in those infected with 93/4286ΩhrpB. In particular, the activation of caspase 11, which is triggered by cytosolic lipopolysaccharide, indicates that during meningococcal infection pyroptosis is induced by intracellular infection after the exit of the bacteria from the internalizing vacuole, a process that is hindered in the hrpB mutant. Overall, these results confirm, in an animal model, that the HrpA/HrpB TPS plays a role in the induction of pyroptosis and suggest a pivotal involvement of pyroptosis in invasive meningococcal disease, paving the way for the use of pyroptosis inhibitors in the adjuvant therapy of the disease.

Chronic Oral Inoculation of Porphyromonas gingivalis and Treponema denticola Induce Different Brain Pathologies in a Mouse Model of Alzheimer Disease.

Periodontitis is a chronic inflammatory disease driven by dysbiosis in subgingival microbial communities leading to increased abundance of a limited number of pathobionts, including Porphyromonas gingivalis and Treponema denticola. Oral health, particularly periodontitis, is a modifiable risk factor for Alzheimer disease (AD) pathogenesis, with components of both these bacteria identified in postmortem brains of persons with AD. Repeated oral inoculation of mice with P. gingivalis results in brain infiltration of bacterial products, increased inflammation, and induction of AD-like biomarkers. P. gingivalis displays synergistic virulence with T. denticola during periodontitis. The aim of the current study was to determine the ability of P. gingivalis and T. denticola, grown in physiologically relevant conditions, individually and in combination, to induce AD-like pathology following chronic oral inoculation of female mice over 12 weeks. P. gingivalis alone significantly increased all 7 brain pathologies examined: neuronal damage, activation of astrocytes and microglia, expression of inflammatory cytokines interleukin 1ß (IL-1ß) and interleukin 6 and production of amyloid-ß plaques and hyperphosphorylated tau, in the hippocampus, cortex and midbrain, compared to control mice. T. denticola alone significantly increased neuronal damage, activation of astrocytes and microglia, and expression of IL-1ß, in the hippocampus, cortex and midbrain, compared to control mice. Coinoculation of P. gingivalis with T. denticola significantly increased activation of astrocytes and microglia in the hippocampus, cortex and midbrain, and increased production of hyperphosphorylated tau and IL-1ß in the hippocampus only. The host brain response elicited by oral coinoculation was less than that elicited by each bacterium, suggesting coinoculation was less pathogenic.

Disseminated cerebral cryptococcoma mimicking glioblastoma - A case report."

We discuss a rare instance of cryptococcoma caused by Cryptococcus gattii in a 55-year-old woman initially treated for suspected COVID bronchopneumonia. The diagnosis posed a challenge due to vague symptoms and unclear imaging findings suggesting malignancy. Postoperative samples confirmed the presence of Cryptococcus gattii through culture of brain tissue and blood. Appropriate therapy was initiated, but despite treatment, it led to a fatal outcome. The case emphasizes the crucial role of microbiologist in early diagnosis of fungal infections of Central Nervous System. Additionally, the delayed diagnosis in immunocompetent individuals highlights the critical need for early recognition and intervention to mitigate potentially fatal outcomes.

Bacteria hijack a meningeal neuroimmune axis to facilitate brain invasion.

The meninges are densely innervated by nociceptive sensory neurons that mediate pain and headache1,2. Bacterial meningitis causes life-threatening infections of the meninges and central nervous system, affecting more than 2.5 million people a year3-5. How pain and neuroimmune interactions impact meningeal antibacterial host defences are unclear. Here we show that Nav1.8+ nociceptors signal to immune cells in the meninges through the neuropeptide calcitonin gene-related peptide (CGRP) during infection. This neuroimmune axis inhibits host defences and exacerbates bacterial meningitis. Nociceptor neuron ablation reduced meningeal and brain invasion by two bacterial pathogens: Streptococcus pneumoniae and Streptococcus agalactiae. S. pneumoniae activated nociceptors through its pore-forming toxin pneumolysin to release CGRP from nerve terminals. CGRP acted through receptor activity modifying protein 1 (RAMP1) on meningeal macrophages to polarize their transcriptional responses, suppressing macrophage chemokine expression, neutrophil recruitment and dural antimicrobial defences. Macrophage-specific RAMP1 deficiency or pharmacological blockade of RAMP1 enhanced immune responses and bacterial clearance in the meninges and brain. Therefore, bacteria hijack CGRP-RAMP1 signalling in meningeal macrophages to facilitate brain invasion. Targeting this neuroimmune axis in the meninges can enhance host defences and potentially produce treatments for bacterial meningitis.

Borrelia burgdorferi Co-Localizing with Amyloid Markers in Alzheimer's Disease Brain Tissues.

BACKGROUND: Infections by bacterial or viral agents have been hypothesized to influence the etiology of neurodegenerative diseases. OBJECTIVE: This study examined the potential presence of Borrelia burgdorferi spirochete, the causative agent of Lyme disease, in brain autopsy tissue of patients diagnosed with either Alzheimer's (AD) or Parkinson's diseases. METHODS: Brain tissue sections from patients with age-matched controls were evaluated for antigen and DNA presence of B. burgdorferi using various methods. Positive Borrelia structures were evaluated for co-localization with biofilm and AD markers such as amyloid and phospho-tau (p-Tau) using immunohistochemical methods. RESULTS: The results showed the presence of B. burgdorferi antigen and DNA in patients with AD pathology and among those, one of them was previously diagnosed with Lyme disease. Interestingly, a significant number of Borrelia-positive aggregates with a known biofilm marker, alginate, were found along with the spirochetal structures. Our immunohistochemical data also showed that Borrelia-positive aggregates co-localized with amyloid and phospho-tau markers. To further prove the potential relationship of B. burgdorferi and amyloids, we infected two mammalian cell lines with B. burgdorferi which resulted in a significant increase in the expression of amyloid-ß and p-Tau proteins in both cells lines post-infection. CONCLUSION: These results indicate that B. burgdorferi can be found in AD brain tissues, not just in spirochete but a known antibiotics resistant biofilm form, and its co-localized amyloid markers. In summary, this study provides evidence for a likely association between B. burgdorferi infections and biofilm formation, AD pathology, and chronic neurodegenerative diseases.

Inositol Metabolism Regulates Capsule Structure and Virulence in the Human Pathogen Cryptococcus neoformans.

The environmental yeast Cryptococcus neoformans is the most common cause of deadly fungal meningitis in primarily immunocompromised populations. A number of factors contribute to cryptococcal pathogenesis. Among them, inositol utilization has been shown to promote C. neoformans development in nature and invasion of central nervous system during dissemination. The mechanisms of the inositol regulation of fungal virulence remain incompletely understood. In this study, we analyzed inositol-induced capsule growth and the contribution of a unique inositol catabolic pathway in fungal development and virulence. We found that genes involved in the inositol catabolic pathway are highly induced by inositol, and they are also highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. This pathway in C. neoformans contains three genes encoding myo-inositol oxygenases that convert myo-inositol into d-glucuronic acid, a substrate of the pentose phosphate cycle and a component of the polysaccharide capsule. Our mutagenesis analysis demonstrates that inositol catabolism is required for C. neoformans virulence and deletion mutants of myo-inositol oxygenases result in altered capsule growth as well as the polysaccharide structure, including O-acetylation. Our study indicates that the ability to utilize the abundant inositol in the brain may contribute to fungal pathogenesis in this neurotropic fungal pathogen. IMPORTANCE The human pathogen Cryptococcus neoformans is the leading cause of fungal meningitis in primarily immunocompromised populations. Understanding how this environmental organism adapts to the human host to cause deadly infection will guide our development of novel disease control strategies. Our recent studies revealed that inositol utilization by the fungus promotes C. neoformans development in nature and invasion of the central nervous system during infection. The mechanisms of the inositol regulation in fungal virulence remain incompletely understood. In this study, we found that C. neoformans has three genes encoding myo-inositol oxygenase, a key enzyme in the inositol catabolic pathway. Expression of these genes is highly induced by inositol, and they are highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. Our mutagenesis analysis indeed demonstrates that inositol catabolism is required for C. neoformans virulence by altering the growth and structure of polysaccharide capsule, a major virulence factor. Considering the abundance of free inositol and inositol-related metabolites in the brain, our study reveals an important mechanism of host inositol-mediated fungal pathogenesis for this neurotropic fungal pathogen.

Expression of immunoproteasome subunits in the brains of Toxoplasma gondii-infected mice.

The immunoproteasomes are specific proteasomes that clear oxidant-damaged proteins under inflammatory conditions in various diseases. Toxoplasma gondii (T. gondii) infects the central nervous system and causeencephalitis. However, the relationship between the immunoproteasomes and brain inflammation during T. gondii infection is not well characterized. In this study, we established an in vivo mouse model of T. gondii PLK strain infection via intraperitoneal injection and evaluated the expression of immunoproteasome subunits in the brains of infected mice. The results demonstrated that first, pathological changes in the brains of infected mice increase in severity over time. Second, following T. gondii infection, activated microglia and astrocytes undergo a series of functional alterations and morphological transformations, including proliferation and migration. Third, T. gondii infection induces expression of inflammatory cytokines, including IFN-γ, IL-1ß, TNF-α, and IL-6. Fourth, the immunoproteasome subunits low-molecular-weight polypeptide 2 (LMP2), LMP7, and LMP10 mRNA and protein levels are significantly upregulated in T. gondii-infected mouse brains, as shown by RT-qPCR and western blot analysis, compared with that in vehicle-treated brains, and their expression is localized in the microglia, astrocytes, and neurons of T. gondii-infected brains, as determined via immunofluorescence staining. Furthermore, the western blot mean gray value for the immunoproteasome subunits and the positive microglia and astrocyte immunohistochemical signals in the brains of T. gondii-infected mice were positively correlated, indicating that the observed relationships were highly significant. Therefore, it was concluded that the induction of the immunoproteasomes is a pathogenic mechanism underlying T. gondii infection-induced inflammation.

Inflammation-relevant microbiome signature of the stroke brain, gut, spleen, and thymus and the impact of exercise.

Stroke remains a significant unmet need in the clinic with few therapeutic options. We, and others, have implicated the role of inflammatory microbiota in stroke secondary cell death. Elucidating this inflammation microbiome as a biomarker may improve stroke diagnosis and treatment. Here, adult Sprague-Dawley rats performed 30 minutes of exercise on a motorized treadmill for 3 consecutive days prior to transient middle cerebral artery occlusion (MCAO). Stroke animals that underwent exercise showed 1) robust behavioral improvements, 2) significantly smaller infarct sizes and increased peri-infarct cell survival and 3) decreasing trends of inflammatory microbiota BAC303, EREC482, and LAB158 coupled with significantly reduced levels of inflammatory markers ionized calcium binding adaptor molecule 1, tumor necrosis factor alpha, and mouse monoclonal MHC Class II RT1B in the brain, gut, spleen, and thymus compared to non-exercised stroke rats. These results suggest that a specific set of inflammatory microbiota exists in central and peripheral organs and can serve as a disease biomarker and a therapeutic target for stroke.

Imaging of COVID-19-associated craniofacial mucormycosis: a black and white review of the "black fungus".

A subset of diabetic COVID-19 patients treated with steroids, oxygen, and/or prolonged intensive care admission develop rhino-orbito-cerebral mucormycosis. Radiologists must have a high index of suspicion for early diagnosis, which prompts immediate institution of antifungal therapy that limits morbidity and mortality. Assessment of disease extent by imaging is crucial for planning surgical debridement. Complete debridement of necrotic tissue improves survival. Imaging features reflect the angioinvasive behaviour of fungal hyphae from the Mucoraceae family, which cause necrotising vasculitis and thrombosis resulting in extensive tissue infarction. Contrast-enhanced magnetic resonance imaging (MRI) is the imaging technique of choice. The classic "black turbinate" on contrast-enhanced imaging represents localised invasive fungal rhinosinusitis (IFRS). A striking radiological feature of disseminated craniofacial disease is non-enhancing devitalised and necrotic soft tissue at the orbits and central skull base. Sinonasal and extrasinonasal non-enhancing lesions in IFRS are secondary to coagulative necrosis induced by fungal elements. Multicompartmental and extrasinonasal tissue infarction is possible without overt bone involvement and caused by the propensity of fungal elements to disseminate from the nasal cavity via perineural and perivascular routes. Fungal vasculitis can result in internal carotid artery occlusion and cerebral infarction. Remnant non-enhancing lesions after surgical debridement portend a poor prognosis. Assessment for the non-enhancing MRI lesion is crucial, as it is a sole independent prognostic factor for IFRS-specific mortality. In this review, we describe common and uncommon imaging presentations of biopsy-proven rhino-orbito-cerebral mucormycosis in a cohort of nearly 40 COVID-19 patients.

M. fortuitum-induced CNS-pathology: Deciphering the role of canonical Wnt signaling, blood brain barrier components and cytokines.

Molecular underpinning of mycobacteria-induced CNS-pathology is not well understood. In the present study, zebrafish were infected with Mycobacterium fortuitum and the prognosis of CNS-pathogenesis studied. We observed M. fortuitum triggers extensive brain-pathology. Evans blue extravasation demonstrated compromised blood-brain barrier (BBB) integrity. Further, decreased expression in tight-junction (TJ) and adherens junction complex (AJC) genes were noted in infected brain. Wnt-signaling has emerged as a major player in host-mycobacterial immunity but its involvement/role in brain-infection is not well studied. Sustained expression of wnt2, wnt3a, fzd5, lrp5/6 and ß-catenin, with concordant decline in degradation complex components axin, gsk3ß and ß-catenin regulator capn2a were observed. The surge in ifng1 and tnfa expression preceding il10 and il4 suggested cytokine-interplay critical in M. fortuitum-induced brain-pathology. Therefore, we suggest adult zebrafish as a viable model for studying CNS-pathology and using the same, conclude that M. fortuitum infection is associated with repressed TJ-AJC gene expression and compromised BBB permeability. Our results implicate Wnt/ß-catenin pathway in M. fortuitum-induced CNS-pathology wherein Th1-type signals facilitate bacterial clearance and Th2-type signals prevent the disease sequel.

Double Vision and Gait Ataxia in an Immunocompetent 9-Year-Old Girl With Intracranial Phaeohyphomycosis.

ABSTRACT: A 9-year-old girl presented with morning headaches associated with vomiting, gait ataxia, and facial and ocular motor nerve palsies. Her initial imaging was concerning for demyelinating disease. After extensive infectious and rheumatologic workup returned negative, she was treated twice with intravenous immunoglobulin and intravenous steroids with near-complete resolution each time. She returned, however, with worsening neurologic deficits and imaging revealing focal ischemic infarction in the brainstem as well as new-onset hydrocephalus. A multispecialty workup was initiated without conclusive diagnosis. A novel, noninvasive test for plasma cell-free DNA established a diagnosis of Cladophialophora bantiana that was confirmed and validated by a brain biopsy taken during a clinical decompensation. Treatment was initiated with systemic voriconazole and intraventricular amphotericin B.

Case Report: Ascending Myelo-Encephalitis after a Penetrating Injury to the Foot: An Atypical Case of Neuromelioidosis.

Organisms penetrate the central nervous system (CNS) via three routes. The commonest is the hematogenous route, and other routes include contiguous or penetrating injury or rarely via retrograde axoplasmic route. Although the axoplasmic highway is often used by viruses, only a few bacteria are known to penetrate the CNS via this route. We present a 57-year-old man who developed a penetrating injury while working in a field. Over the next 4 months, he developed pain at the site of the poorly healing wound, which ascended up the right leg and presented as a conus-cauda syndrome. Magnetic resonance imaging (MRI) showed an enhancing intradural intramedullary enhancing lesion in the conus on the right side with cord edema from D11 to L1 level. Extensive evaluation was negative, and he continued to progress to holocord myelitis and developed bilateral corticospinal tract lesions ("tractopathy") in the brain stem and internal capsule. He died after developing a right-sided cerebritis with mass effect. Tissue biopsy from the brain at the time of decompressive craniectomy grew Burkholderia pseudomallei and confirmed a diagnosis of neuromelioidosis (NM). We reviewed the literature for NM, its variable presentations, and the concept of an "infectious tractopathy" and imaging findings which could generate suspicion of this entity.

Case Report: Isolated Central Nervous System Melioidosis from a Non-Endemic Area.

Central nervous system (CNS) melioidosis is a rare neurological infectious disease which carries a high mortality. We describe a previously healthy middle-aged female, who presented to us with left-sided hemiparesis and was on antitubercular therapy from a previous presumed diagnosis of CNS tuberculoma. Non-characteristic imaging picture, multiple negative body fluid cultures, and positive Cerebrospinal fluid galactomannan led to a further delay in diagnosis. Gram stain of the tissue obtained from brain biopsy revealed Gram-negative rods in "safety pin" appearance. By picking up the colonies that appeared on blood agar and MacConkey agar, the identification of the clinical isolates was performed using VITEK® matrix (BioMérieux, Marcy-L'Etoile, France)-assisted laser desorption ionization time-of-flight mass spectrometry (VITEK MALDI TOF MS database version 3.2) which revealed Burkholderia pseudomallei. After the institution of appropriate treatment, she survived but with significant morbidity. A high index of suspicion should be kept for such previously healthy individuals belonging to non-endemic areas, where presentation is suspicious of an infective etiology, but not improving despite appropriate therapy. This may help in early recognition and institution of recommended treatment so that mortality can be avoided.

Cryptococcus neoformans-astrocyte interactions: effect on fungal blood brain barrier disruption, brain invasion, and meningitis progression.

Cryptococcus neoformans is an opportunistic, neurotropic, and encapsulated fungus that causes life-threatening cryptococcal meningitis (CM), especially in regions of the world where AIDS is endemic. The polysaccharide capsule of C. neoformans is the fungus major virulent factor, being copiously released during infection and causing immunosuppressive defects in the host. Although the capsular material is commonly associated with reactive astrocytes in fatal CM, little is known about the molecular and cellular interactions among astroglia and C. neoformans. As astrocytes also make up the neurovascular unit at the blood-brain barrier (BBB), which C. neoformans must transverse to colonize the central nervous system and cause CM; these cells may play a significant regulatory role in the prevention and progression of infection. For example, astrocytes are implicated in neurological disease including the regulation of cerebral intracranial pressure, immune function, and water homeostasis. Hence, in this review, we provide a general overview of astroglia biology and discuss the current knowledge on C. neoformans-astrocyte interactions including their involvement in the development of CM. This "gliocentric view" of cerebral cryptococcosis suggests that therapeutic interventions particularly targeting at preserving the neuroprotective function of astrocytes may be used in preventing and managing C. neoformans BBB transmigration, brain invasion, colonization, and meningitis.

Microbiome-gut-brain axis in cancer treatment-related psychoneurological toxicities and symptoms: a systematic review.

PURPOSE: The microbiome-gut-brain (MGB) axis provides a dynamic model to understand associations between the gut microbiota and psychoneurological comorbidities. The role of the MGB axis in cancer treatment-related psychoneurological symptoms (PNS) remains unknown. The purpose of this study was to conduct a systematic review of the existing literature to identify the influence of the gut microbiota on cancer and cancer treatment-related PNS and toxicities mediated by the MGB axis. METHODS: We searched the databases of PubMed, Embase, and Web of Science from their earliest records to October 2019. All studies identified in the database searches were screened by title and abstract, followed by a review of the full texts. The Johns Hopkins Nursing Evidence-Based Practice Model was adopted to assess the evidence levels and qualities; the Joanna Briggs Institute critical appraisal tools were used to assess the methodological quality and the possibility of bias for each included study. All the study findings were combined, synthesized, and presented through narrative format. RESULTS: Six studies were included in this systematic review. These studies primarily focused on cancer survivorship while receiving chemotherapy, and they were conducted between 2016 and 2019. The gut microbiome was assessed via fecal samples, which were analyzed using 16S rRNA sequencing approaches. With small-scale studies, the gut microbiota was associated with cancer treatment-related PNS, including fatigue, anxiety, depression, sleep disturbance, cognitive impairment, and chemotherapy-induced peripheral neuropathy. A higher relative abundance of Bacteroides was associated with a higher level of fear of cancer recurrence but a higher relative abundance of Lachnospiraceae.g and Ruminococcus was associated with a lower level in fear of cancer recurrence. Changes in fatigue interference were associated with the frequency of genera Faecalibacterium and Prevotella, and changes in anxiety were associated with the frequency of genera Coprococcus and Bacteroides. CONCLUSIONS: The gut microbiota showed significant associations with cancer treatment-related PNS. Recent work regarding the MGB axis in cancer psychoneurological toxicities focused primarily on individual toxicity and symptoms in cancer survivors with chemotherapy exposure. Associations between the gut microbiota and PNS should be further studied in cancer populations across different ages, cancer types, and treatment modalities.

Central nervous system aspergillosis in immunocompetent patients: Case series and literature review.

The aim of this study was to investigate the clinical characteristics of central nervous system (CNS) aspergillosis in immunocompetent patients.This study enrolled six immunocompetent patients diagnosed with CNS aspergillosis. Additionally, we reviewed the clinical profiles for 28 cases reported in the literature. The age, gender, etiology of Aspergillus infection, clinical manifestations, location of the lesion, treatment, and prognosis were analyzed.There were 19 men (average age, 54.6 ±â€Š14.3 years) and 15 women (average age, 47.0 ±â€Š19.4 years). The clinical manifestations included headache (55.9%; n = 19), visual impairment (32.4%; n = 11), diplopia (32.4%; n = 11), hemiplegia (20.6%; n = 7), fever (17.6%; n = 6), and epilepsy (8.8%; n = 3). According to the radiological features, CNS aspergillosis lesions were divided into two subtypes: parenchymal lesions in the cerebral lobes (n = 11), and meningeal lesions in the meninges (n = 23). The patients with meningeal lesions are easy to be complicated with more serious cerebrovascular diseases, such as subarachnoid hemorrhage and massive infarction. Most of the lesions in brain parenchyma were abscess formation, and magnetic resonance imaging showed ring enhancement. The clinical diagnosis of Aspergillus infection was mainly based on brain biopsy (n = 14), autopsy (n = 8), pathological examination of adjacent brain tissues (n = 7), cerebrospinal fluid (CSF) or tissue culture (n = 3), and second-generation sequencing analysis of the CSF (n = 3). Clinical improvement was achieved in 23 cases, and 11 patients succumbed to the disease. Voriconazole treatment was effective in 24 (70.6%) cases.Immunocompetent subjects are also at risk for Aspergillus infections. Concomitant cerebrovascular diseases are common in patients with CNS aspergillosis, especially in patients with meningeal aspergillosis. Parenchymal aspergillosis lesions are usually localized and manifest as brain abscesses with annular enhancement on magnetic resonance imaging. Biopsy, CSF culture, and next-generation sequencing are mainstream diagnostic modalities. Voriconazole is an effective treatment for Aspergillus infection, and early diagnosis and treatment should be highlighted.

A case of Mycobacterium bovis Bacillus Calmette-Guérin (BCG) strain meningitis and ventriculitis following BCG vaccination.

The Bacillus Calmette-Guérin (BCG) vaccine is widely used worldwide. Intracranial manifestation as an adverse event of BCG is extremely rare. A previously healthy 16-month-old boy was referred to our hospital for eye contact difficulties and progressive gait disturbance lasting two months. He was inoculated with BCG at seven months of age. Brain magnetic resonance imaging (MRI) revealed hydrocephalus with widespread and disseminated enhancement lesions with thickening of the third ventricle floor, and brain tissue pathologically showed non-caseous granulomatous inflammation. Immunosuppressive therapies were initiated because of a provisional diagnosis of neurosarcoidosis. Three months later, a positive polymerase chain reaction (PCR) result for the Mycobacterium tuberculosis complex was obtained. Eventually, M. bovis (BCG Tokyo 172 strain) was identified in the cerebrospinal fluid (CSF) and shunt tube culture. The prolonged use of antituberculosis drugs and multiple shunt replacement surgeries were needed for recovery. There was no evidence of immunodeficiency. Unfortunately, he had severe neurological sequelae of bilateral blindness and neurodevelopmental delay. Our purpose in this report was to highlight the potential for intracranial manifestations of adverse reactions related to BCG vaccination. We propose that the CSF PCR assay of Mycobacterium tuberculosis (MTB) complex should be applied repeatedly in children suspected of intractable neurosarcoidosis, with a history of BCG vaccination.

Bacteria elevate extracellular adenosine to exploit host signaling for blood-brain barrier disruption.

Bacterial meningitis remains a substantial cause of mortality worldwide and survivors may have severe lifelong disability. Although we know that meningeal bacterial pathogens must cross blood-central nervous system (CNS) barriers, the mechanisms which facilitate the virulence of these pathogens are poorly understood. Here, we show that adenosine from a surface enzyme (Ssads) of Streptococcus suis facilitates this pathogen's entry into mouse brains. Monolayer translocation assays (from the human cerebrovascular endothelium) and experiments using diverse inhibitors and agonists together demonstrate that activation of the A1 adenosine receptor signaling cascade in hosts, as well as attendant cytoskeleton remodeling, promote S. suis penetration across blood-CNS barriers. Importantly, our additional findings showing that Ssads orthologs from other bacterial species also promote their translocation across barriers suggest that exploitation of A1 AR signaling may be a general mechanism of bacterial virulence.

An Antivirulence Approach for Preventing Cryptococcus neoformans from Crossing the Blood-Brain Barrier via Novel Natural Product Inhibitors of a Fungal Metalloprotease.

Cryptococcus neoformans (Cn) is the leading cause of fungal meningitis, a deadly disease with limited therapeutic options. Dissemination to the central nervous system hinges on the ability of Cn to breach the blood-brain barrier (BBB) and is considered an attribute of Cn virulence. Targeting virulence instead of growth for antifungal drug development has not been fully exploited despite the benefits of this approach. Mpr1 is a secreted fungal metalloprotease not required for fungal growth, but rather, it functions as a virulence factor by facilitating Cn migration across the BBB. This central role for Mpr1, its extracellular location, and lack of expression in mammalian cells make Mpr1 a high-value target for an antivirulence approach aimed at developing therapeutics for cryptococcal meningitis. To test this notion, we devised a large-scale screen to identify compounds that prohibited Cn from crossing the BBB by selectively blocking Mpr1 proteolytic activity, without inhibiting the growth of Cn A phytochemical natural product-derived library was screened to identify new molecular scaffolds of prototypes unique to a Cn microecosystem. Of the 240 pure natural products examined, 3 lead compounds, abietic acid, diosgenin, and lupinine inhibited Mpr1 proteolytic activity with 50% inhibitory concentration (IC50) values of <10 µM, displayed little to no mammalian cell toxicity, and did not affect Cn growth. Notably, the lead compounds blocked Cn from crossing the BBB, without damaging the barrier integrity, suggesting the bioactive molecules had no off-target effects. We propose that these new drug scaffolds are promising candidates for the development of antivirulence therapy against cryptococcal meningitis.IMPORTANCE Fungal infections like cryptococcal meningitis are difficult to resolve because of the limited therapies available. The small arsenal of antifungal drugs reflect the difficulty in finding available targets in fungi because like mammalian cells, fungi are eukaryotes. The limited efficacy, toxicity, and rising resistance of antifungals contribute to the high morbidity and mortality of fungal infections and further underscore the dire but unmet need for new antifungal drugs. The traditional approach in antifungal drug development has been to target fungal growth, but an attractive alternative is to target mechanisms of pathogenesis. An important attribute of Cryptococcus neoformans (Cn) pathogenesis is its ability to enter the central nervous system. Here, we describe a large-scale screen that identified three natural products that prevented Cn from crossing the blood-brain barrier by inhibiting the virulence factor Mpr1 without affecting the growth of Cn We propose that compounds identified here could be further developed as antivirulence therapy that would be administered preemptively or serve as a prophylactic in patients at high risk for developing cryptococcal meningitis.