Search Results (884)

Microglia, the brain’s resident innate immune cells, play a fundamental role in maintaining neural homeostasis and mediating responses to injury or infection. Upon activation, microglia undergo morphological and functional changes, including phenotypic switching between pro- and anti-inflammatory types and the release of different inflammatory mediators. These processes contribute to neuroprotection and the pathogenesis of various central nervous system (CNS) disorders. Mast cells, although sparsely located in the brain, exert a significant influence on neuroinflammation through their interactions with microglia. Through degranulation and secretion of different mediators, mast cells disrupt the blood–brain barrier and modulate microglial responses, including alteration of microglial phenotypes. Notably, mast cell-derived factors, such as histamine, interleukins, and tryptase, activate microglia through various pathways including protease-activated receptor 2 and purinergic receptors. These interactions amplify inflammatory cascades via various signaling pathways. Previous studies have revealed an exceedingly complex crosstalk between mast cells and microglia suggesting a bidirectional regulation of CNS immunity, implicating their cooperation in both neurodegenerative progression and repair mechanisms. Here, we review some of the diverse communication pathways involved in this complex interplay. Understanding this crosstalk may offer novel insights into the cellular dynamics of neuroinflammation and highlight potential therapeutic targets for a variety of CNS disorders. Full article

Schizophrenia is a challenging multifactorial neuropsychiatric disease that involves interactions between genetic susceptibility and environmental insults. Increasing evidence implicates viral infections as significant environmental contributors, particularly during sensitive neurodevelopmental periods. This review synthesises current findings on the viral hypothesis of schizophrenia, encompassing a wide array of neurotropic viruses, including influenza viruses, herpesviruses (HSV-1 and 2, CMV, VZV, EBV, HHV-6 and 8), hepatitis B and C viruses, HIV, HERVs, HTLV, Zika virus, BoDV, coronaviruses (including SARS-CoV-2), and others. These pathogens can contribute to schizophrenia through mechanisms such as direct microinvasion, persistent central nervous system infection, immune-mediated neuroinflammation, molecular mimicry, and the disturbance of the blood–brain barrier. Prenatal exposure to viral infections can trigger maternal immune activation, resulting in cytokine-mediated alterations in the neurological development of the foetus that persist into adulthood. Genetic studies highlight the role of immune-related loci, including major histocompatibility complex polymorphisms, in modulating susceptibility to infection and neurodevelopmental outcomes. Clinical data also support the “mild encephalitis” hypothesis, suggesting that a subset of schizophrenia cases involve low-grade chronic neuroinflammation. Although antipsychotics have some immunomodulatory effects, adjunctive anti-inflammatory therapies show promise, particularly in treatment-resistant cases. Despite compelling associations, pathogen-specific links remain inconsistent, emphasising the need for longitudinal studies and integrative approaches such as viromics to unravel causal relationships. This review supports a “multi-hit” model in which viral infections interfere with hereditary and immunological susceptibilities, enhancing schizophrenia risk. Elucidating these virus–immune–brain interactions may facilitate the discovery of biomarkers, targeted prevention, and novel therapeutic strategies for schizophrenia. Full article

The focal “hot spot” neuropathologies in COVID-19 infection are revealing footprints of a hidden underlying collapse of a novel ultrafast ultradian Piezo2 signaling system within the nervous system. Paradoxically, the same initiating pathophysiology may underpin the systemic findings in COVID-19 infection, namely the multiorgan SARS-CoV-2 infection-induced vascular pathologies and brain–body-wide systemic pro-inflammatory signaling, depending on the concentration and exposure to infecting SARS-CoV-2 viruses. This common initiating microdamage is suggested to be the primary damage or the acquired channelopathy of the Piezo2 ion channel, leading to a principal gateway to pathophysiology. This Piezo2 channelopathy-induced neural switch could not only explain the initiation of disrupted cell–cell interactions, metabolic failure, microglial dysfunction, mitochondrial injury, glutamatergic synapse loss, inflammation and neurological states with the central involvement of the hippocampus and the medulla, but also the initiating pathophysiology without SARS-CoV-2 viral intracellular entry into neurons as well. Therefore, the impairment of the proposed Piezo2-induced quantum mechanical free-energy-stimulated ultrafast proton-coupled tunneling seems to be the principal and critical underlying COVID-19 infection-induced primary damage along the brain axes, depending on the loci of SARS-CoV-2 viral infection and intracellular entry. Moreover, this initiating Piezo2 channelopathy may also explain resultant autonomic dysregulation involving the medulla, hippocampus and heart rate regulation, not to mention sleep disturbance with altered rapid eye movement sleep and cognitive deficit in the short term, and even as a consequence of long COVID. The current opinion piece aims to promote future angles of science and research in order to further elucidate the not entirely known initiating pathophysiology of SARS-CoV-2 infection. Full article

Primary amoebic meningoencephalitis (PAM) is a rapidly progressive and fulminant disease that affects the central nervous system caused by the free-living amoeba Naegleria fowleri. The adhesion to extracellular matrix (ECM) proteins is considered as one of the key steps in the success of the infection and could represent an interesting target to be explored in the prevention and treatment of the disease. In this work, the effect of two sesquiterpenes with proven anti-Naegleria activity on the adhesion of the parasite was evaluated using an in vitro ECM-based model, compared with the reference drugs amphotericin B and staurosporine. Both laurinterol and (+)-elatol inhibited the adhesion of the N. fowleri trophozoites to the main proteins of the ECM when treating them at different concentrations and exposure times. This work not only reinforces the therapeutic potential of laurinterol and (+)-elatol against N. fowleri infection but also introduces the application of ECM-based adhesion assays as a novel and valuable tool for screening candidate compounds that disrupt host–pathogen interactions critical to PAM pathogenesis. Full article

The agents of prion diseases have the capacity to efficiently infect susceptible hosts by peripheral routes and to project to clinical target areas of the central nervous system (CNS) via peripheral nerves. Understanding the process of prion spread from the site of infection to the CNS may allow us to identify novel therapeutic strategies. To investigate the mechanism involved in the intranerval transit of 263K scrapie prions in golden Syrian hamsters (GSHs), we transected the sciatic nerve at increasing times post-footpad injection and recorded the incubation periods as estimates of the efficiency of infection. We calculated that intranerval transit of this strain of scrapie is at least 10 times faster than previously reported and may reach 50 mm/day, similar to other neurotropic viruses. By in vivo exposure/injection of sciatic nerves to 263K infectivity, we have also shown that prion entry likely occurs via nerve terminals rather than by direct contact with the sciatic nerve. Application of this experimental approach in other forms of prion diseases could allow verification of the timing of neuroinvasion, a relevant parameter for the definition of therapeutic interventions. Full article

Objective: The interactions between the central nervous system (CNS) and the immune system suggest that immune mechanisms may be effective in the pathogenesis of epilepsy and epileptic seizures. Although studies on the natural immune response and epilepsy are continuing, it is not yet clear whether the interaction of the current immune system is due to epilepsy itself or antiepileptic drugs (AEDs), since epileptic patients also use AEDs There are a limited number of studies that have reported an increased incidence of upper respiratory tract infections (URTIs) in patients during levetiracetam (LEV) treatment. Therefore, we aimed to report our experience regarding the effect of LEV monotherapy on the complete blood count (CBC), immunoglobulin (Ig) levels, and lymphocyte subgroups in the interictal period in children and adolescents with epilepsy. Methods: This study enrolled 31 children who presented with epilepsy and underwent LEV monotherapy for at least one year (patient group) and 43 healthy children (control group). The CBC parameters (hemoglobin (hb), lymphocytes, leukocytes, neutrophils, and platelets), Ig levels (IgA, IgM, IgG, and IgE), and lymphocyte subsets (CD3, CD4, CD8, CD4/CD8 ratio, CD19, CD56, NKT cells, and Treg cells) were measured and compared between the two groups. The patients were also investigated regarding the frequency and types of infections that they experienced in the first month and first year of the study, and these data were compared between the patient group and the control group. In addition, the same parameters and the frequency of infection were compared among the patient subgroups (focal and generalized seizures). Results: The results of the present study indicate that there were no significant differences in the CBC parameters, lymphocyte subsets, or Ig levels between the patient group and the control group. The comparison among the patient subgroups was similar; however, the CD4/CD8 ratio was lower in the patient subgroup with focal seizures. In addition, there were no significant differences in the frequency or type of infections experienced one month and one year of the study between the patient group and the control group, and likewise for the patient subgroups (focal and generalized seizures). Conclusions: The present study demonstrated that LEV monotherapy did not increase the incidence of infection, and there were no significant effects on the CBC or on the humoral or cellular immune system in epileptic children. These findings also suggest that the CD4/CD8 ratio among lymphocyte subgroups is lower in patients with focal seizures. However, the epilepsy subgroups had a relatively small sample size; therefore, further prospective studies involving a larger patient population are needed to establish the association between LEV monotherapy and lymphocyte subgroups in patients with epilepsy. Full article

The effective suppression of inflammation using disease-modifying therapies is essential in the treatment of multiple sclerosis (MS). Anti-CD20 monoclonal antibodies are commonly used long-term as maintenance therapies, largely due to the lack of reliable biomarkers to guide dosing and evaluate treatment response. However, prolonged use increases the risk of infections and other immune-mediated side effects. The unique ability of brain-derived blood extracellular vesicles (EVs) to cross the blood–brain barrier and reflect the central nervous system (CNS) immune status has sparked interest in their potential as biomarkers. This study aimed to assess whether blood-derived L1CAM⁺ EVs could serve as biomarkers of treatment response to rituximab (RTX) in patients with relapsing-remitting MS (RRMS). Serum samples (n = 25) from the baseline (month 0) and after 6 months were analyzed from the RTX arm of the ongoing randomized clinical trial OVERLORD-MS (comparing anti-CD20 therapies in RRMS patients) and were compared with serum samples from healthy controls (n = 15). Baseline cerebrospinal fluid (CSF) samples from the same study cohort were also included. EVs from both serum and CSF samples were characterized, considering morphology, size, and concentration, using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The immunophenotyping of EV surface receptors was performed using flow cytometry with the MACSPlex exosome kit, while label-free quantitative proteomics of EV protein cargo was conducted using a proximity extension assay (PEA). TEM confirmed the presence of EVs with the expected round morphology with a diameter of 50–150 nm. NTA showed significantly higher concentrations of L1CAM⁺ EVs (p < 0.0001) in serum total EVs and EBNA1⁺ EVs (p < 0.01) in serum L1CAM⁺ EVs at baseline (untreated) compared to in healthy controls. After six months of RTX therapy, there was a significant reduction in L1CAM⁺ EV concentration (p < 0.0001) and the downregulation of TNFRSF13B (p = 0.0004; FC = −0.49) in serum total EVs. Additionally, non-significant changes were observed in CD79B and CCL2 levels in serum L1CAM⁺ EVs at baseline compared to in controls and after six months of RTX therapy. In conclusion, L1CAM⁺ EVs in serum showed distinct immunological profiles before and after rituximab treatment, underscoring their potential as dynamic biomarkers for individualized anti-CD20 therapy in MS. Full article

Introduction: Acute Myeloid Leukemia (AML) is a hematologic malignancy characterized by the clonal expansion of myeloid progenitors. While it primarily affects the bone marrow, extramedullary relapse occurs in 3–5% of cases, and it is linked to poor prognosis. Central nervous system (CNS) involvement presents diagnostic challenges due to nonspecific symptoms. CNS manifestations include leptomeningeal dissemination, nerve infiltration, parenchymal lesions, and myeloid sarcoma, occurring at any disease stage and frequently asymptomatic. Methods: A 62-year-old man with a recent history of AML in remission presented with diplopia and aching paresthesias in the left periorbital region spreading to the left frontal area. The diagnostic workup included neurological and hematological evaluation, lumbar puncture, brain CT, brain magnetic resonance imaging (MRI) with contrast, and dermatological evaluation with skin biopsy due to the appearance of nodular skin lesions on the abdomen and thorax. Results: Neurological evaluation showed hypoesthesia in the left mandibular region, consistent with left trigeminal nerve involvement, extending to the periorbital and frontal areas, and impaired adduction of the left eye with divergent strabismus in the primary position due to left oculomotor nerve palsy. Brain MRI showed an equivocal thickening of the left oculomotor nerve without enhancement. Cerebrospinal fluid (CSF) analysis initially showed elevated protein (47 mg/dL) with negative cytology; a repeat lumbar puncture one week later detected leukemic cells. Skin biopsy revealed cutaneous AML localization. A diagnosis of AML relapse with CNS and cutaneous localization was made. Salvage therapy with FLAG-IDA-VEN (fludarabine, cytarabine, idarubicin, venetoclax) and intrathecal methotrexate, cytarabine, and dexamethasone was started. Subsequent lumbar punctures were negative for leukemic cells. Due to high-risk status and extramedullary disease, the patient underwent allogeneic hematopoietic stem cell transplantation. Post-transplant aplasia was complicated by septic shock; the patient succumbed to an invasive fungal infection. Conclusions: This case illustrates the diagnostic complexity and poor prognosis of extramedullary AML relapse involving the CNS. Early recognition of neurological signs, including cranial nerve dysfunction, is crucial for timely diagnosis and management. Although initial investigations were negative, further analyses—including repeated CSF examinations and skin biopsy—led to the identification of leukemic involvement. Although neuroleukemiosis cannot be confirmed without nerve biopsy, the combination of clinical presentation, neuroimaging, and CSF data strongly supports the diagnosis of extramedullary relapse of AML. Multidisciplinary evaluation remains essential for detecting extramedullary relapse. Despite treatment achieving CSF clearance, the prognosis remains unfavorable, underscoring the need for vigilant clinical suspicion in hematologic patients presenting with neurological symptoms. Full article

With the rise in immunocompromised individuals and patients with immune-related comorbidities such as COVID-19, the rate of fungal infections is growing. This increase, along with the current plateau in antifungal drug development, has made understanding the pathogenesis and dissemination of these organisms more pertinent than ever. The mouse model of fungal infection, while informative on a basic scientific level, has severe limitations in terms of translation to the human disease. Here we present data supporting the implementation of the human cerebral organoid model, which is generated from human embryonic stem cells and accurately recapitulates relevant brain cell types and structures, to study fungal infection and dissemination to the central nervous system (CNS). This approach provides direct insight into the relevant pathogenesis of specific fungal organisms in human tissues where in vivo models are impossible. With this model system we assessed the specific brain tropisms and cellular effects of fungal pathogens known to cross the blood–brain barrier (BBB), such as Cryptococcus neoformans. We determined the effects of this fungal pathogen on the overall gross morphology, cellular architecture, and cytokine release from these model organoids. Furthermore, we demonstrated that C. neoformans penetrates and invades the organoid tissue and remains present throughout the course of infection. These results demonstrate the utility of this new model to the field and highlight the potential for this system to elucidate fungal pathogenesis to develop new therapeutic strategies to prevent and treat the disseminated stages of fungal diseases such as cryptococcal meningitis. Full article

While viral pathogens are often subdivided into neurotropic and non-neurotropic categories, systemic inflammation caused by non-neurotropic viruses still possesses the ability to alter the central nervous system (CNS). Studies of CNS disease induced by viral infection, whether neurotropic or not, are presented with a unique set of challenges. First, because brain biopsies are rarely necessary to diagnose viral-associated neurological disorders, antemortem tissue samples are not readily available for study and human pathological studies must rely on end-stage, postmortem evaluations. Second, in vitro models fail to fully capture the nuances of an intact immune system, necessitating the use of animal models to fully characterize pathogenesis and identify potential therapeutic approaches. Non-human primates (NHP) represent a particularly attractive animal model in that they overcome many of the limits posed by more distant species and most closely mirror human disease pathogenesis and susceptibility. Here, we review NHP infection models of viruses known to infect and/or replicate within cells of the CNS, including West Nile virus, the equine encephalitis viruses, Zika virus, and herpesviruses, as well as those known to alter the immune status of the brain in the absence of significant CNS penetrance, including human immunodeficiency virus (HIV) in the current era of combination antiretroviral therapy (cART) and the coronavirus of severe acute respiratory syndrome (SARS)-CoV−2. This review focuses on viruses with an established role in causing CNS disease, including encephalitis, meningitis, and myelitis and NHP models of viral infection that are directly translatable to the human condition through relevant routes of infection, comparable disease pathogenesis, and responses to therapeutic intervention. Full article

Exophiala dermatitidis is an emerging black yeast recognized in both superficial and life-threatening infections, including those in immunocompetent hosts. This narrative review focuses on recent developments (mostly between 2019 and 2025) in two major areas. First, we examined the clinical and epidemiological background of E. dermatitidis, with particular focus on its involvement in cystic fibrosis and CARD9 deficiency, as well as central nervous system, ocular, and systemic infections. Second, we address the molecular basis of its pathogenicity, with particular attention to melanin production, capsule formation, and metabolic adaptation. We also discuss diagnostic challenges and antifungal susceptibility, highlighting gaps between laboratory studies and clinical outcomes. Full article

Treatment for HIV infection has become more manageable due to advances in combination antiretroviral therapy (cART). However, HIV still significantly affects the central nervous system (CNS) in infected individuals, even with effective plasma viral suppression, due to persistent viral reservoirs and chronic neuroinflammation. This ongoing inflammation contributes to the development of HIV-associated neurocognitive disorders (HANDs), including dementia and Alzheimer’s disease-like pathology. These complications are particularly prevalent among the aging population with HIV. This review aims to provide a comprehensive overview of HAND, with a focus on the contribution of oxidative stress induced by HIV-mediated reactive oxygen species (ROS) production through viral proteins such as gp120, Tat, Nef, Vpr, and reverse transcriptase. In addition, we discuss current and emerging therapeutic interventions targeting HAND, including antioxidant strategies and poly (ADP-ribose) polymerase (PARP) inhibitors. These are potential adjunctive approaches to mitigate neuroinflammation and oxidative damage in the CNS. Full article

Introduction: Sepsis-associated encephalopathy (SAE) is an acute brain dysfunction secondary to systemic infection, occurring without direct central nervous system involvement. Despite its clinical relevance, reliable biomarkers for diagnosing SAE and assessing its severity remain limited. This study aimed to evaluate the feasibility of amide proton transfer-weighted (APTw) chemical exchange saturation transfer (CEST) MRI as a non-invasive molecular imaging technique for detecting metabolic alterations related to neuroinflammation in SAE. Using a lipopolysaccharide (LPS)-induced rat model, we focused on hippocampal changes associated with neuronal inflammation. Materials and Methods: Twenty-one Sprague–Dawley rats (8 weeks old, male) were divided into three groups: control (CTRL, n = 7), LPS-induced sepsis at 5 mg/kg (LPS05, n = 7), and 10 mg/kg (LPS10, n = 7). Sepsis was induced via a single intraperitoneal injection of LPS. APTw imaging was performed using a 7 T preclinical MRI system, and signal quantification in the hippocampus was conducted using the magnetization transfer ratio asymmetry analysis. Results and Discussion: APTw imaging at 7 T demonstrated significantly elevated hippocampal APTw signals in SAE model rats (LPS05 and LPS10) compared to the control (CTRL) group: CTRL (−1.940 ± 0.207%) vs. LPS05 (−0.472 ± 0.485%) (p < 0.001) and CTRL vs. LPS10 (−0.491 ± 0.279%) (p < 0.001). However, no statistically significant difference was observed between the LPS05 and LPS10 groups (p = 0.994). These results suggest that APTw imaging can effectively detect neuroinflammation-related metabolic alterations in the hippocampus. Conclusion: Our findings support the feasibility of APTw CEST imaging as a non-invasive molecular MRI technique for SAE, with potential applications in diagnosis, disease monitoring, and therapeutic evaluation. Full article

Pseudorabies virus (PRV) can infect a wide range of animal species, including swine and rodents. Infection in pigs is associated with significant economic losses in the global pork industry and is characterized by acute, often fatal disease, as well as central nervous system (CNS) invasion, which leads to neurological manifestations. Although PRV replication has been extensively characterized in certain murine neuronal cell lines such as Neuro-2a, the mechanisms underlying PRV-induced neuroinflammatory injury and necroptosis remain largely unclear. In this study, Kunming mice and mouse astrocytes (C8-D1A) were infected with PRV-GXLB-2013 at different doses to evaluate neurological injury and inflammatory responses. Given that the NF-κB/MLKL signaling pathway was found to be activated during PRV infection, a selective MLKL inhibitor, necrosulfonamide (NSA), was applied to investigate the role of necroptosis in PRV-induced neuroinflammatory damage. Mice infected with higher viral doses showed increased mortality, severe neurological symptoms, elevated brain inflammation, and pathological changes. In C8-D1A cells, PRV infection significantly upregulated inflammatory cytokines and key components of the NF-κB/MLKL pathway. Importantly, NSA treatment markedly reduced these inflammatory responses, mitochondrial damage, and cellular necrosis. Collectively, these findings suggest that PRV infection triggers neuroinflammatory injury through the activation of necroptosis and the NF-κB/MLKL signaling pathway. This study provides novel mechanistic insights into PRV-induced neurological damage and highlights potential therapeutic targets for intervention. Full article

The gut microbiota constitutes a complex community of microorganisms (including bacteria, viruses, fungi, and protozoa) within the intestinal tract. Over the years, an increasing number of studies have highlighted the bidirectional communication between the gut microbiota and the central nervous system (CNS), a relationship commonly referred to as the “microbiota–gut–brain axis”. In particular, the crosstalk between the gut microbiota and the brain has been associated with the pathogenesis and progression of various CNS disorders. Phages, or bacteriophages, viruses that specifically infect bacteria, constitute the most abundant viral component within the gut microbiota. However, despite their abundance and significance in the gut microbial community, studies exploring the relationship between phages and the CNS remain surprisingly limited. This review examines the biological interplay between gut-resident phages and the CNS. Furthermore, we discuss the current literature linking phages to CNS-related pathologies. Full article