The spectrum of central nervous system manifestations in leprosy: a systematic review of published case reports and case series.

BACKGROUND: This systematic review aimed to investigate central nervous system (CNS) involvement in leprosy by analysing multiple cohort studies, individual cases and case series. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. PubMed, Scopus and Embase databases were searched up to 8 July 2023, using a predefined search strategy. Inclusion criteria included patients diagnosed with leprosy with evidence of CNS involvement. The quality of the included cases was evaluated using the Joanna Briggs Institute checklist. RESULTS: A total of 34 records were identified, including 18 cohort studies and 16 reports describing 27 isolated cases. Autopsies revealed macroscopic changes in the spinal cord, neurofibrillary tangles and senile plaques. Mycobacterium leprae was detected in neurons of the medulla oblongata and spinal cord using PCR and phenolic glycolipid 1 staining. Cerebrospinal fluid (CSF) analysis showed inflammatory changes, increased gamma globulins and detection of Mycobacterium leprae antigens and antibodies. In 21 patients (78%), spinal cord/brachial plexus abnormities were detected. In the majority, MRI revealed T2/fluid-attenuated inversion recovery (FLAIR) hyperintensity in the cervical cord. In patients with brainstem involvement, T2/FLAIR hyperintensity was noted in the cerebellar peduncles, facial nerve nuclei and/or other cranial nerve nuclei. Brain parenchymal involvement was noted in three patients. CONCLUSIONS: This systematic review provides evidence of CNS involvement in leprosy, based on autopsy findings, neuroimaging, CSF analysis and neurophysiological studies.

Bacterial inhibition of Fas-mediated killing promotes neuroinvasion and persistence.

Infections of the central nervous system are among the most serious infections1,2, but the mechanisms by which pathogens access the brain remain poorly understood. The model microorganism Listeria monocytogenes (Lm) is a major foodborne pathogen that causes neurolisteriosis, one of the deadliest infections of the central nervous system3,4. Although immunosuppression is a well-established host risk factor for neurolisteriosis3,5, little is known about the bacterial factors that underlie the neuroinvasion of Lm. Here we develop a clinically relevant experimental model of neurolisteriosis, using hypervirulent neuroinvasive strains6 inoculated in a humanized mouse model of infection7, and we show that the bacterial surface protein InlB protects infected monocytes from Fas-mediated cell death by CD8+ T cells in a manner that depends on c-Met, PI3 kinase and FLIP. This blockade of specific anti-Lm cellular immune killing lengthens the lifespan of infected monocytes, and thereby favours the transfer of Lm from infected monocytes to the brain. The intracellular niche that is created by InlB-mediated cell-autonomous immune resistance also promotes Lm faecal shedding, which accounts for the selection of InlB as a core virulence gene of Lm. We have uncovered a specific mechanism by which a bacterial pathogen confers an increased lifespan to the cells it infects by rendering them resistant to cell-mediated immunity. This promotes the persistence of Lm within the host, its dissemination to the central nervous system and its transmission.

Human Gut Microbiota in Health and Selected Cancers.

The majority of the epithelial surfaces of our body, and the digestive tract, respiratory and urogenital systems, are colonized by a vast number of bacteria, archaea, fungi, protozoans, and viruses. These microbiota, particularly those of the intestines, play an important, beneficial role in digestion, metabolism, and the synthesis of vitamins. Their metabolites stimulate cytokine production by the human host, which are used against potential pathogens. The composition of the microbiota is influenced by several internal and external factors, including diet, age, disease, and lifestyle. Such changes, called dysbiosis, may be involved in the development of various conditions, such as metabolic diseases, including metabolic syndrome, type 2 diabetes mellitus, Hashimoto's thyroidis and Graves' disease; they can also play a role in nervous system disturbances, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and depression. An association has also been found between gut microbiota dysbiosis and cancer. Our health is closely associated with the state of our microbiota, and their homeostasis. The aim of this review is to describe the associations between human gut microbiota and cancer, and examine the potential role of gut microbiota in anticancer therapy.

Histoplasmosis of the Central Nervous System: A Case Series between 1990 and 2019 in French Guiana.

Disseminated histoplasmosis is the most frequent acquired immunodeficiency syndrome-defining illness in French Guiana. Paradoxically, central nervous system (CNS) involvement has been scarcely described. We aimed to identify CNS histoplasmosis in our territory. We conducted an observational, multicentric, descriptive, and retrospective study including patients with proven or probable CNS histoplasmosis according to the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MGS). The study population consisted of patients admitted in one of the hospitals of French Guiana between January 1, 1990 and December 31, 2019. During the study period, 390 cases of HIV-associated histoplasmosis were recorded, in which six of them had CNS infections with Histoplasma capsulatum. The male to female sex ratio was 0.25, and the median age at diagnosis was 37.5 years. The median CD4 count was 42 cells/mm3 ([IQR: 29-60]). All patients had disseminated histoplasmosis. Usual signs of meningitis were observed in three patients and focal signs in four patients. One patient had no neurological signs. The median time between the first cerebral symptoms and diagnosis was 22.4 days (IQR 9.5-36.2). Two patients died within a month after diagnosis. In conclusion, few proven CNS localizations of histoplasmosis were observed on 30-year study in French Guiana. This low proportion suggests that the documentation of CNS involvement is often not ascertained for lack of awareness of this particular presentation, and for lack of rapid and sensitive diagnostic tools.

Case Report: Central Nervous System Immune Reconstitution Inflammatory Syndrome Related to Bacterial Meningitis.

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) describes clinical characteristics that may be observed in previously immunocompromised patients during rapid restoration of immunity function in the presence of a pathogen. There have been no reports about CNS-IRIS related to bacterial meningitis so far. Here, we report a 24-year-old pregnant female patient with bacterial meningitis. Her clinical and neuroradiological condition worsened after induced labor despite great effective anti-infective therapy. CNS-IRIS was considered. Corticosteroids were administered, and the patient gradually recovered. We present the first case of CNS-IRIS associated with bacterial meningitis.

Dietary restrictions modulate the gut microbiota: Implications for health and disease.

The health benefits of carefully restricting the energy intake in a strategic manner whilst avoiding malnutrition are widely discussed. In the recent years, the great impact of the gut microbiota on its host has been clarified more and more. Since the gut microbiota produces a number of metabolites and molecules that can affect host metabolism, modulating it with dietary restriction can influence the health and the progression of disease of its host on various levels. This review comprises 15 studies investigating the effect of different variants of fasting and caloric restriction on the gastrointestinal microbiome and its metabolites. The data suggest that changing the gut microbiota composition by dietary restriction has the potential to positively influence the progression of several diseases such as obesity, diabetes, neurological diseases or inflammatory bowel disease. Finally, the relevance of the findings for clinical practice is evaluated and approaches for future research are proposed.

The Microbiota-Gut-Brain Axis: From Motility to Mood.

The gut-brain axis plays an important role in maintaining homeostasis. Many intrinsic and extrinsic factors influence signaling along this axis, modulating the function of both the enteric and central nervous systems. More recently the role of the microbiome as an important factor in modulating gut-brain signaling has emerged and the concept of a microbiota-gut-brain axis has been established. In this review, we highlight the role of this axis in modulating enteric and central nervous system function and how this may impact disorders such as irritable bowel syndrome and disorders of mood and affect. We examine the overlapping biological constructs that underpin these disorders with a special emphasis on the neurotransmitter serotonin, which plays a key role in both the gastrointestinal tract and in the brain. Overall, it is clear that although animal studies have shown much promise, more progress is necessary before these findings can be translated for diagnostic and therapeutic benefit in patient populations.

Antifungal efficacy of isavuconazole and liposomal amphotericin B in a rabbit model of Exserohilum rostratum meningoencephalitis: A preclinical paradigm for management of CNS phaeohyphomycosis.

Treatment options for Exserohilum rostratum meningoencephalitis and other causes of phaeohyphomycosis of the central nervous system (CNS) are limited, while mortality and morbidity remain high. We therefore evaluated isavuconazole, a new antifungal triazole in comparison to liposomal amphotericin B (LAMB), in vitro and in the rabbit model of Exserohilum rostratum meningoencephalitis. We hypothesized that isavuconazole alone or in combination with LAMB or micafungin may be alternative options for treatment of CNS phaeohyphomycosis. We therefore investigated the in vitro antifungal activity of isavuconazole alone or in combination with amphotericin B deoxycholate (DAMB) or micafungin and efficacy of treatment with isavuconazole and LAMB in a rabbit model of experimental E. rostratum meningoencephalitis. Combination checkerboard plates were used to determine the minimum inhibitory concentrations, minimal lethal concentrations, fractional inhibitory concentration indices, and Bliss surface analysis of isavuconazole and amphotericin B deoxycholate (DAMB), either alone or in combination. As there were no in vitro synergistic or antagonistic interactions for either combination of antifungal agents against the E. rostratum isolates, in vivo studies were conducted with isavuconazole and LAMB as monotherapies. Rabbits were divided in following groups: treated with isavuconazole at 60 mg/kg/d (ISAV60), LAMB at 5.0 (LAMB5), 7.5 (LAMB7.5), and 10 mg/kg/d (LAMB10), and untreated controls (UC). In ISAV60-, LAMB5-, LAMB7.5-, and LAMB10-treated rabbits, significant reductions of fungal burden of E. rostratum in cerebral, cerebellar, and spinal cord tissues (P < 0.01) were demonstrated in comparison to those of UC. These antifungal effects correlated with significant reduction of CSF (1→3)-ß-D-glucan levels vs UC (P < 0.05). These data establish new translational insights into treatment of CNS phaeohyphomycosis.

Treatment and mortality outcomes in patients with other extrapulmonary cryptococcal disease compared with central nervous system disease.

BACKGROUND: Determining the extent of cryptococcal disease (CD) is key to therapeutic management. Treatment with fluconazole is only recommended for localised pulmonary disease. Induction therapy with amphotericin B (AmB) and flucytosine is recommended for disease at other sites, irrespective of central nervous system (CNS) involvement, but this is not often followed in patients without meningitis. In this study, we compared treatment and mortality between patients with CD of the CNS and other extrapulmonary (OE) sites. METHODS: This is a retrospective, single-centre study of all hospitalised patients with nonpulmonary cryptococcal infection from 2002 to 2015 who underwent lumbar puncture. Demographics, predisposing factors, comorbidities, clinical presentation, laboratory values, antifungal treatment and mortality data were collected to evaluate 90-day mortality and treatment differences between patients with OE and CNS CD. Survival analysis was performed using multivariable Cox regression analysis. RESULTS: Of 193 patients analysed, 143 (74%) had CNS CD and 50 (26%) had OE CD. Ninety-day mortality was 23% and similar between the OE and CNS CD groups (22% vs 23%, p = .9). In the comorbidity-adjusted multivariable Cox regression model, mortality risk was similar in the OE and CNS groups. Fewer patients with OE CD received induction therapy with AmB and flucytosine compared to those with CNS disease (28% vs 71.3%, p < .001). CONCLUSION: Patients with OE CD had similar 90-day mortality compared to those with CNS disease. Despite current guideline recommendations, patients with OE disease were less likely to receive appropriate induction therapy with AmB and flucytosine compared to patients with CNS disease.

Microbiota-Gut-Brain Axis: New Therapeutic Opportunities.

The traditional fields of pharmacology and toxicology are beginning to consider the substantial impact our gut microbiota has on host physiology. The microbiota-gut-brain axis is emerging as a particular area of interest and a potential new therapeutic target for effective treatment of central nervous system disorders, in addition to being a potential cause of drug side effects. Microbiota-gut-brain axis signaling can occur via several pathways, including via the immune system, recruitment of host neurochemical signaling, direct enteric nervous system routes and the vagus nerve, and the production of bacterial metabolites. Altered gut microbial profiles have been described in several psychiatric and neurological disorders. Psychobiotics, live biotherapeutics or substances whose beneficial effects on the brain are bacterially mediated, are currently being investigated as direct and/or adjunctive therapies for psychiatric and neurodevelopmental disorders and possibly for neurodegenerative disease, and they may emerge as new therapeutic options in the clinical management of brain disorders.

Neurological symptoms and mortality associated with Streptococcus gallolyticus subsp. pasteurianus in calves.

Suppurative meningitis-meningoencephalitis (M-ME) is a sporadic disease in neonatal ungulates and only a few studies have reported the involvement of Streptococcus bovis/Streptococcus equinus complex (SBSEC) members in bovine neonatal M-ME. The SBSEC taxonomy was recent revised and previous biotype II/2 was reclassified as S. gallolyticus subsp. pasteurianus (SGP). The aim of this study was to describe a case of fatal neonatal neurological syndrome associated with SGP in calves. Ten calves were monitored because of neurological hyperacute symptoms associate with bilateral hypopyon and death. They were not fed with maternal colostrum; two of them died and were subjected to bacteriological, histopathological and biomolecular analysis as well as antibiotic susceptibility test. Both animals presented lesions mostly concentrated to meninges and brain and had bilateral hypopyon. Nine strains isolated in purity from brain, ocular humors and colon were identified as S. bovis group by using the API Strep system and as S. gallolyticus by using the 16S rRNA sequence. Two of these strains where subjected to WGS analysis that confirmed the sub-species identification and the clonality of the two SGP strains. The strains were found resistant to OT, SXT, MTZ and EN and susceptible to AMP, AMC, KZ and CN. We hypothesized that the syndrome observed could be due to the lack of maternal colostrum feeding. A timely and precise diagnosis could have likely prevented the death of the calves and, since the zoonotic potential of SBSECs members is known, accurate and rapid identification is required.

Microbiota-gut brain axis involvement in neuropsychiatric disorders.

Introduction: The microbiota-gut brain (MGB) axis is the bidirectional communication between the intestinal microbiota and the brain. An increasing body of preclinical and clinical evidence has revealed that the gut microbial ecosystem can affect neuropsychiatric health. However, there is still a need of further studies to elucidate the complex gene-environment interactions and the role of the MGB axis in neuropsychiatric diseases, with the aim of identifying biomarkers and new therapeutic targets, to allow early diagnosis and improving treatments. Areas covered: To review the role of MGB axis in neuropsychiatric disorders, prediction and prevention of disease through exploitation, integration, and combination of data from existing gut microbiome/microbiota projects and appropriate other International '-Omics' studies. The authors also evaluated the new technological advances to investigate and modulate, through nutritional and other interventions, the gut microbiota. Expert opinion: The clinical studies have documented an association between alterations in gut microbiota composition and/or function, whereas the preclinical studies support a role for the gut microbiota in impacting behaviors which are of relevance to psychiatry and other central nervous system (CNS) disorders. Targeting MGB axis could be an additional approach for treating CNS disorders and all conditions in which alterations of the gut microbiota are involved.

Fecal Microbial Transplantation for Diseases Beyond Recurrent Clostridium Difficile Infection.

As microbiome research has moved from associative to mechanistic studies, the activities of specific microbes and their products have been investigated in the development of inflammatory bowel diseases, cancer, metabolic syndrome, and neuropsychiatric disorders. Findings from microbiome research have already been applied to the clinic, such as in fecal microbiota transplantation for treatment of recurrent Clostridium difficile infection. We review the evidence for associations between alterations in the intestinal microbiome and gastrointestinal diseases and findings from clinical trials of fecal microbiota transplantation. We discuss opportunities for treatment of other diseases with fecal microbiota transplantation, based on findings from small clinical and preclinical studies.

Modeling gut-brain interactions in zebrafish.

Mounting clinical and experimental evidence suggests the gut-brain interplay as a novel important paradigm in translational neuroscience, including the critical role for gut microbiota in modulating brain development and behavior, as well as neuroimmune and neuroendocrine responses. Animal models are an indispensable tool in studying the central nervous system (CNS) disorders and their mechanisms. Recently, the zebrafish (Danio rerio) has become a powerful new model organism in neuroscience, including studying the gut-brain axis. Here, we discuss zebrafish models of gut-brain interplay, endocrine and toxicological effects of zebrafish microbiota, and their impact on neuroimmune and behavioral processes. We particularly emphasize the growing utility of zebrafish models in gut-brain research, as they foster future discoveries of new interconnections between these systems.

The role of the gut microbiota in development, function and disorders of the central nervous system and the enteric nervous system.

The gut microbiota has emerged as an environmental factor that modulates the development of the central nervous system (CNS) and the enteric nervous system (ENS). Before obtaining its own microbiota, eutherian foetuses are exposed to products and metabolites from the maternal microbiota. At birth, the infants are colonised by microorganisms. The microbial composition in early life is strongly influenced by the mode of delivery, the feeding method, the use of antibiotics and the maternal microbial composition. Microbial products and microbially produced metabolites act as signalling molecules that have direct or indirect effects on the CNS and the ENS. An increasing number of studies show that the gut microbiota can modulate important processes during development, including neurogenesis, myelination, glial cell function, synaptic pruning and blood-brain barrier permeability. Furthermore, numerous studies indicate that there is a developmental window early in life during which the gut microbial composition is crucial and perturbation of the gut microbiota during this period causes long-lasting effects on the development of the CNS and the ENS. However, other functions are readily modulated in adult animals, including microglia activation and neuroinflammation. Several neurobehavioural, neurodegenerative, mental and metabolic disorders, including Parkinson disease, autism spectrum disorder, schizophrenia, Alzheimer's disease, depression and obesity, have been linked to the gut microbiota. This review focuses on the role of the microorganisms in the development and function of the CNS and the ENS, as well as their potential role in pathogenesis.

Definition and Consensus Diagnostic Criteria for Neurosarcoidosis: From the Neurosarcoidosis Consortium Consensus Group.

Importance: The Neurosarcoidosis Consortium Consensus Group, an expert panel of physicians experienced in the management of patients with sarcoidosis and neurosarcoidosis, engaged in an iterative process to define neurosarcoidosis and develop a practical diagnostic approach to patients with suspected neurosarcoidosis. This panel aimed to develop a consensus clinical definition of neurosarcoidosis to enhance the clinical care of patients with suspected neurosarcoidosis and to encourage standardization of research initiatives that address this disease. Observations: The work of this collaboration included a review of the manifestations of neurosarcoidosis and the establishment of an approach to the diagnosis of this disorder. The proposed consensus diagnostic criteria, which reflect current knowledge, provide definitions for possible, probable, and definite central and peripheral nervous system sarcoidosis. The definitions emphasize the need to evaluate patients with findings suggestive of neurosarcoidosis for alternate causal factors, including infection and malignant neoplasm. Also emphasized is the need for biopsy, whenever feasible and advisable according to clinical context and affected anatomy, of nonneural tissue to document the presence of systemic sarcoidosis and support a diagnosis of probable neurosarcoidosis or of neural tissue to support a diagnosis of definite neurosarcoidosis. Conclusions and Relevance: Diverse disease presentations and lack of specificity of relevant diagnostic tests contribute to diagnostic uncertainty. This uncertainty is compounded by the absence of a pathognomonic histologic tissue examination. The diagnostic criteria we propose are designed to focus investigations on NS as accurately as possible, recognizing that multiple pathophysiologic pathways may lead to the clinical manifestations we currently term NS. Research recognizing the clinical heterogeneity of this diagnosis may open the door to identifying meaningful biologic factors that may ultimately contribute to better treatments.

Microbiota-gut-brain axis: Interaction of gut microbes and their metabolites with host epithelial barriers.

The gastrointestinal barrier and the blood brain barrier represent an important line of defense to protect the underlying structures against harmful external stimuli. These host barriers are composed of epithelial and endothelial cells interconnected by tight junction proteins along with several other supporting structures. Disruption in host barrier structures has therefore been implicated in various diseases of the gastrointestinal tract and the central nervous system. While there are several factors that influence host barrier, recently there is an increasing appreciation of the role of gut microbiota and their metabolites in regulating barrier integrity. In the current issue of Neurogastroenterology and Motility, Marungruang et al. describe the effect of gastrointestinal barrier maturation on gut microbiota and the blood brain barrier adding to the growing evidence of microbiota-barrier interactions. In this mini-review I will discuss the effect of gut microbiota on host epithelial barriers and its implications for diseases associated with disrupted gut-brain axis.