Progressive multiple sclerosis (PMS) is an autoimmune demyelinating disease of the central nervous system (CNS) in humans. PMS is defined by neuroinflammation and axonal damage with advancing neurological disabilities, although the underlying molecular mechanisms remain uncertain. To gain insight into the proteomic aspects of PMS, we used mass spectrometry to investigate proteomic profiles and specific protein changes in matched CNS tissues (white matter, cortex, and lesions) from persons with PMS and age/sex-matched other disease controls (ODCs). These studies were examined further using proteomes of primary human neural cell types (e.g., neurons, astrocytes, microglia, oligodendrocyte progenitor cells/OPCs) and CNS tissues from PMS mouse models. Extracellular matrix (ECM) related proteins, including the annexin, S100, and AHNAK protein families, were significantly enriched in PMS white matter, especially within demyelinated lesions compared to ODC tissues. These enriched proteins showed increased abundance in astrocytes, microglia, and OPCs compared to neurons. Annexin, S100, and AHNAK family proteins were also increased in the CNS of the cuprizone and experimental autoimmune encephalitis mouse models. These findings highlight the importance of ECM protein induction in CNS glial cells during PMS while providing potential therapeutic targets for future investigation. The underlying molecular mechanisms of neuroinflammation and axonal damage in progressive multiple sclerosis remains unclear. Here, authors show proteomics results of human progressive multiple sclerosis brain tissues and found extracellular matrix proteins (annexin, S100, AHNAK families) were enriched in lesions and white matter.

Hexavalent chromium (Cr[VI]), one of the major heavy metals in fine particulate matter (PM2.5), has been linked to increased risks of neurological impairment and brain cancer. However, the direct effect of Cr(VI) on brain cells remains unclear. In this study, we investigated the cell type–specific cytotoxicity of Cr(VI) at environmentally relevant concentrations to cultured human neurons and astrocytes. Our findings showed that higher concentrations of Cr(VI) were required to induce cell death in human astrocytes (IC50 of 32.05 µM at 24 h) than in the human neurons (IC50 of 24.55 µM at 24 h). The neurotoxicity effects associated with elevated intracellular chromium levels included DNA damage (decreased poly[ADP–ribose] polymerase expression), mitochondria-mediated apoptosis (increased caspase 3/7 activation), and autophagy (increased light chain 3 [LC3]–II to LC3–I levels accompanied by decreased p62 expression). Activation of the MAPK signalling pathway triggered Cr(VI) –induced brain death. Furthermore, Cr(VI) exposure induced S–phase accumulation in U-87 MG cells by altering cell cycle–related protein expression, specifically by upregulating CDK inhibitors (p21, p27, and p53) and downregulating cyclin B, cyclin D, and CDK4. Together, these findings demonstrate that the mechanisms underlying Cr(VI)-induced neurotoxicity were similar between the two cell types and further highlight the importance of increased awareness of chromium pollution and its impact on human health.

Long COVID (LC) is a multisystem, post-infectious conditions diagnosed ≥3 months after acute SARS-CoV-2 infection and marked by relapsing, persistent, or progressive symptoms, especially fatigue, post-exertional symptom exacerbation and neuropsychiatric syndromes. We synthesized evidence suggesting that LC arises from intersecting pathways including viral persistence, intestinal dysbiosis and barrier compromise with microbial translocation, innate immune activation with neutrophil extracellular traps (NET) and thromboinflammation, and immune dysregulation with features of exhaustion and autoimmunity. These processes adversely impact blood-brain barrier (BBB) function and lead to neuroinflammation. We propose a mechanistic model in which viral antigens and translocated microbial products amplify pro-inflammatory networks promoting immunothrombosis and tissue hypoperfusion. Hematogenous and gut-brain pathways may then deliver inflammatory mediators to the central nervous system (CNS), resulting in BBB disruption and glial activation that underpin nervous system disorders in LC. Treatment regimens aimed at lowering antigen load, restoring mucosal barrier integrity and modulating myeloid/coagulation pathways may warrant investigation as novel therapeutic strategies to treat LC.

Prevalence and incidence of HIV among people aged 50 years and older continue to rise worldwide, generating increasing awareness among care providers, scientists, and the HIV community about the importance of brain health in older adults with HIV. Many age-related factors that adversely affect brain health can occur earlier and more often among people with HIV, including epigenetic ageing, chronic medical conditions (eg, cardiovascular disease), and age-related syndromes (eg, frailty). Extensive dialogue between HIV community leaders, health-care providers, and scientists has led to the development of a multidimensional response strategy to protect and enhance brain health in people ageing with HIV that spans across public health, clinical spaces, and research spaces. This response strategy was informed by integrated ageing care frameworks and is centred on prevention, early detection, and management of brain health issues associated with HIV (eg, neurocognitive disorders), with specific considerations for low-resource or middle-resource countries. A collaborative, international, and data-informed update of the diagnostic criteria for HIV-associated neurocognitive disorders is a cornerstone of the proposed response strategy. The proposed response strategy includes a dynamic, international, online knowledge hub that will provide a crucial community resource for emerging evidence on the brain health of people ageing with HIV.

With the declaration of monkeypox virus (MPXV) infection as a global health emergency in 2022 by the World Health Organization and its ongoing presence, orthopoxviruses have garnered increasing attention, including their capacity to cause neurological disease. Indeed, the mpox syndrome caused by MPXV infection is recapitulated in humans for several other orthopoxviruses, including variola (VARV, the cause of smallpox), vaccinia (VACV), camelpox (CMPX) and cowpox (CPXV) viruses, albeit with variable disease severities. In addition to prototypic signs and symptoms of Orthopoxvirus infections, such as fever, swollen lymph nodes, malaise and skin lesions, MPXV-infected individuals also develop neurological syndromes such as headaches, myalgias, seizures, altered consciousness and encephalopathy/encephalitis. MRI of the brains of MPXV-infected persons can display hyperintensities consistent with brain oedema. Pleocytosis has also been reported in the CSF from persons with MPXV infections, implying active infection of the CNS. Of note, newborn rodents, or animals with severe combined immune deficiency, were found to be susceptible to MPXV infection with evidence that the virus can cross the blood-brain barrier. In the present review, we highlight the current understanding of Orthopoxvirus neuropathogenesis together with germane diagnostic and therapeutic considerations.

HIV-1 persists in the body even when treatment suppresses viral replication. This persistence is due in part to the virus integrating into the DNA of infected cells. While it is known that HIV-1 can integrate into many different tissues, it remains unclear whether integration patterns differ across anatomical sites. This study investigated how the location and characteristics of HIV-1 integration sites vary across distinct tissues in people living with HIV-1 subtype B during the early years of the pandemic, before modern treatment was widely available. Integration site data were obtained from matched samples from the esophagus, blood, stomach, duodenum, and colon, and from unmatched brain tissue. We evaluated how frequently the virus integrated near different genomic features, including gene regions, repetitive elements, and predicted DNA structures, and compared integration patterns across tissues and individuals. We show that integration site patterns differ by tissue. In brain tissue, HIV integrates less frequently into genes and more frequently into specific repetitive elements and accessible regions of DNA. We also find that integration near unusual DNA shapes varies by tissue, and that certain integration hotspots are shared while others are unique. Genes involved in HIV-1-related diseases are frequently targeted across tissues. This study reveals that HIV-1 integration patterns are shaped by the tissue environment. These findings suggest that the long-term persistence of HIV-1 depends in part on tissue-specific integration site features, with potential implications for disease risk and treatment strategies. Kohio et al. map HIV-1 integration sites across multiple tissues from early infections. The results identify brain-specific patterns and tissue-dependent preferences that may influence HIV persistence and disease risk. HIV can stay in the body for life by hiding inside the DNA of infected cells. This makes it hard to completely remove the virus, even with strong treatment. In this study, researchers explored whether HIV hides in different ways depending on where in the body the infected cells are found. They examined tissues from several parts of the body from people living with HIV before modern treatments were available. The study found that HIV inserts its genetic material in different spots depending on the tissue. For example, in the brain, the virus avoids genes and hides in less active parts of the DNA. These findings may help scientists understand why HIV acts differently in different areas of the body, which could improve future treatments.

Peroxisomes are membrane-bounded organelles that contribute to a range of physiological functions in eukaryotic cells. In the central nervous system (CNS), peroxisomes are implicated in several vital homeostatic functions including, but not limited to, reactive oxygen species signaling and homeostasis; generation of critical myelin sheath components (including ether phospholipids); biosynthesis of neuroprotective docosahexaenoic acid; breakdown of neurotoxic metabolites (such as very-long chain fatty acids); and, intriguingly, glial activation and response to inflammatory stimuli. Indeed, peroxisomes play a critical role in modulating inflammatory responses and are key regulators of the mitochondrial antiviral signaling (MAVS) protein-mediated response to infections. The importance of peroxisomes in CNS physiology is exemplified by the peroxisome biogenesis disorders (PBDs), a spectrum of inherited disorders of peroxisome assembly and/or abundance, that are characterized in part by neurological manifestations ranging from severe cerebral malformations to vision and hearing loss, depending on the individual disorder. Recently, peroxisome dysfunction has been implicated in neurological diseases associated with neuroinflammation including Alzheimer’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and Parkinson’s disease while also contributing to the pathogenesis of neurotropic viruses including SARS-CoV-2, Human Pegivirus, HIV-1 and Zika virus. In the present review, we examine the diverse roles that peroxisomes serve in CNS health before reviewing more recent studies investigating peroxisome dysfunction in inflammatory brain disorders and also highlight potential peroxisomal targets for diagnostic biomarkers and therapeutic interventions.

Despite effective viral suppression with modern antiretroviral therapy (ART), HIV-1 persists in latent reservoirs across multiple tissues. Integration into the host genome is essential for viral persistence, yet the characteristics of these reservoir sites across anatomical locations remain poorly understood. To address this, we analyzed integration sites from matched esophagus, PBL/PBMC, stomach, duodenum, colon, and unmatched brain tissue samples of individuals infected with HIV-1 subtype B. The virus used in this study was from 1993, an early stage of the HIV pandemic, providing insights into integration patterns before extensive ART use. Our analysis examined genomic feature enrichment, proximity to non-B DNA structures, integration hotspots, and site overlap across tissues and individuals. We identified a distinct integration pattern in brain tissue, characterized by reduced gene targeting and increased enrichment in Short Interspersed Nuclear Elements (SINEs) and DNase I hypersensitivity sites (DHS). Tissue-specific preferences for integration near non-B DNA structures were evident, alongside shared and unique hotspots across tissues and individuals. Notably, genes associated with HIV-related diseases were frequent integration targets. These findings underscore the complex interplay between viral integration, host genetics, and tissue-specific factors, highlighting the potential role of integration sites in disease development. ### Competing Interest Statement The authors have declared no competing interest.

Cadmium is a non-essential element and neurotoxin that causes neuroinflammation, which leads to neurodegenerative diseases and brain cancer. To date, there are no specific or effective therapeutic agents to control inflammation and alleviate cadmium-induced progressive destruction of brain cells. Fluoroquinolones (FQs), widely used antimicrobials with effective blood-brain barrier penetration, show promise in being repurposed as anti-inflammatory drugs. Therefore, we aimed to test the efficacy of repurposed FQs for the treatment of cadmium-induced inflammation using cultures of U-87 MG human astrocytes and primary human astrocytes. Both FQs abrogated cadmium-induced interleukin (IL)-6 and IL-8 release from human astrocytes in a concentration and time-dependent manner, although levofloxacin had a stronger inhibitory effect than moxifloxacin. The downregulation of inflammatory cytokine release occurred with a concomitant reduction in cadmium-induced elevations in p65 nuclear factor-κB (NF-κB) and extracellular signal-regulated kinases (ERKs) 1/2 phosphorylation. Additionally, levofloxacin treatment significantly alleviated cadmium-induced activation of phosphorylated NF-κB translocation and toll-like receptor (TLR)-4/signal transducer and activator of transcription (STAT) 3 signaling. Transcriptome analysis revealed that modulation of inflammation-related pathways was the most enriched after FQ treatment. Our data suggest that FQs, particularly levofloxacin, attenuate the inflammatory process mediated by cadmium in human astrocytes. These effects may be mediated, at least in part, by inhibition of immune pathways regulated by TLR4, STAT3, ERK MAPK, and NF-κB.

Neuropsychiatric disorders including depression or anxiety are common in persons with post-COVID-19 condition (PCC). In a clinical cohort, interleukin (IL)-1beta, -2, -6, -8, -10, and TNF-alpha were significantly elevated in serum from PCC compared to control subjects while serum IL-6 levels were selectively increased among PCC subjects with depression. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection of primary human neural cells showed viral replication in astrocytes, although IL-6 was released by abortively-infected microglia. In C57BL6/J mice intranasally infected with mouse-adapted SARS-CoV-2, viral RNA was detected in the lungs and multiple brain regions, which persisted in 33 % of infected animals up to 21 days post-infection (dpi), associated with increased brainstem IL-6 expression. As catecholamines are implicated in mood and anxiety, we analyzed monoamine oxidase (MAO) expression, revealing elevated transcript and protein levels for both MAO isoforms in infected human and mouse brain tissues, particularly in glial cells, which was correlated with increased MAO enzymatic activity. Neurobehavioral assessments showed depressive behaviors until 7dpi, transitioning to anxiety behaviors by 21dpi among virus-infected mice, which was attenuated by MAO inhibition. These findings highlight the immunometabolic mechanisms, involving cytokine-enzyme interactions that contribute to PCC-associated neuropsychiatric syndromes while also identifying potential diagnostic and therapeutic options.

Objective:To discover microRNA (miRNA)-RNA transcript interactions dysregulated in brains from persons with HIV-associated neurocognitive disorder (HAND), we investigated RNA expression using machine learning tools.Design:Brain-derived host RNA transcript and miRNA expression was examined from persons with or without HAND using bioinformatics platforms.Methods:By combining next generation sequencing, droplet digital (dd)PCR quantitation of HIV-1 genomes, with bioinformatics and statistical tools, we investigated differential RNA expression in frontal cortex from persons without HIV [HIV(-)], with HIV without brain disease [HIV(+)], with HAND, or HAND with encephalitis (HIVE).Results:Expression levels for 147 transcripts and 43 miRNAs showed a minimum four-fold difference between clinical groups with a predominance of antiviral (type I interferon) signaling-related, neural cell maintenance-related, and neurodevelopmental disorder-related genes that was validated by gene ontology and molecular pathway inferences. Scale of signal-to-noise ratio (SSNR) and biweight midcorrelation (bicor) analyses identified 14 miRNAs and 45 RNA transcripts, which were highly correlated and differentially expressed (P <= 0.05). Machine learning applications compared regression models predicated on HIV-1 DNA, or RNA viral quantities that disclosed miR-4683 and miR-154-5p were dominant variables associated with differential expression of host RNAs. These miRNAs were also associated with antiviral-related, cell maintenance-related, and neurodevelopmental disorder-related genes.Conclusion:Antiviral as well as neurodevelopmental disorder-related pathways in brain were associated with HAND, based on correlated RNA transcripts and miRNAs. Integrated molecular methods with machine learning offer insights into disease mechanisms, underpinning brain-related biotypes among persons with HIV that could direct clinical care.

Objective: To discover microRNA (miRNA)-RNA transcript interactions dysregulated in brains from persons with HIV-associated neurocognitive disorder (HAND), we investigated RNA expression using machine learning tools. Design: Brain-derived host RNA transcript and miRNA expression was examined from persons with or without HAND using bioinformatics platforms. Methods: By combining next generation sequencing, droplet digital (dd)PCR quantitation of HIV-1 genomes, with bioinformatics and statistical tools, we investigated differential RNA expression in frontal cortex from persons without HIV (HIV[-]), with HIV without brain disease (HIV[+]), with HIV-associated neurocognitive disorder (HAND), or HAND with encephalitis (HIVE). Results: Expression levels for 147 transcripts and 43 miRNAs showed a minimum 4-fold difference between clinical groups with a predominance of antiviral (Type I interferon) signaling-, neural cell maintenance-, and neurodevelopmental disorder-related genes that was validated by gene ontology and molecular pathway inferences. Scale of signal-to-noise ratio (SSNR) and biweight midcorrelation (bicor) analyses identified 14 miRNAs and 45 RNA transcripts, which were highly correlated and differentially expressed (p ≤ 0.05). Machine learning applications compared regression models predicated on HIV-1 DNA, or RNA viral quantities that disclosed miR-4683 and miR-154-5p were dominant variables associated with differential expression of host RNAs. These miRNAs were also associated with antiviral-, cell maintenance-, and neurodevelopmental disorder-related genes. Conclusions: Antiviral as well as neurodevelopmental disorder-related pathways in brain were associated with HAND, based on correlated RNA transcripts and miRNAs. Integrated molecular methods with machine learning offer insights into disease mechanisms, underpinning brain-related biotypes among persons with HIV that could direct clinical care.

Limosilactobacillus reuteri is an immunomodulatory bacterium enriched in non-industrialized microbiomes, making it a therapeutic candidate for chronic diseases. However, effects of L. reuteri strains in mouse models of multiple sclerosis have been contradictory. Here, we show that treatment of spontaneous relapsing-remitting experimental autoimmune encephalomyelitis (EAE) mice with L. reuteri R2lc, a strain that activates the aryl hydrocarbon receptor (AhR) through the pks gene cluster, resulted in severe pathology. In contrast, a pks mutant and a pks-negative strain (PB-W1) failed to exacerbate EAE and exhibited reduced pathology compared to R2lc despite earlier disease onset in PB-W1 mice. Differences in pathology occurred in parallel with a pks-dependent downregulation of AhR-related genes, reduced occludin expression in the forebrain, and altered concentrations of immune cells. This work establishes a molecular foundation for strain-specific effects on autoimmunity, which has implications for our understanding of how microbes contribute to chronic conditions and the selection of microbial therapeutics.

Understanding how viruses affect cellular pathways during infection may facilitate development of host cell-targeted therapeutics with broad-spectrum antiviral activity. The interferon (IFN) response is critical for reducing replication and pathogenesis of many viruses including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. Mounting evidence indicates that peroxisomes which are best known as metabolic organelles, function in the IFN response. Recently, we reported that the Wnt/β-catenin signaling pathway strongly suppresses peroxisome biogenesis. Here, we show that SARS-CoV-2 infection activates Wnt/β-catenin signaling and hypothesized that pharmacological inhibition of this pathway would result in increased peroxisome formation and enhanced IFN production. Indeed, Wnt/β-catenin signaling potently inhibits replication of SARS-CoV-2 and other pathogenic RNA viruses in vitro and reduces viral load, inflammation and clinical symptoms in a mouse model of COVID-19. As such, targeting this cellular pathway may have prophylactic and/or therapeutic value in reducing the disease burden caused by emerging viral pathogens.

Objectives: The aim of this study was to define the frequency, risk factors, and clinical outcomes of both AIDS-defining and non-AIDS-defining neurologic infections among people with HIV (PWH). Design: We conducted a retrospective observational cohort study by linking the clinical database at the Southern Alberta HIV Clinic (SAC) with the regional hospital and microbiology databases to identify cases and the associated morbidity and mortality for these neurologic infections from 1995 to 2018. Methods: Neurologic infections were categorized into AIDS-defining and non-AIDS defining. Annual incidence rates per 1000 person-years were calculated. Cox proportional hazards models estimated adjusted hazard ratios (aHR) and 95% confidence intervals of risk factors for neurologic infections in PWH and mortality outcomes. Results: Among 2910 PWH contributing 24 237 years of follow-up, 133 (4.6%) neurologic infections were identified; 107 (80%) were AIDS-defining and 26 (20%) non-AIDS defining. While the incidence of AIDS-defining neurologic infections declined over time, no change was seen in incidence of non-AIDS defining infections. The risk of having any neurologic infection was greater among black PWH (aHR = 2.5 [1.6–4.0]) (vs. white PWH) and those with a CD4 + T-cell nadir of less than 200 cells/μl (aHR = 6.6 [4.0–11.1]) (vs. ≥200 cells/μl). More AIDS-defining neurologic infections occurred in PWH with lower CD4 + T-cell counts and higher HIV viral loads. PWH with any neurologic infections experienced more seizures, strokes, all-cause mortality (aHR = 2.2 [1.5–3.2] and HIV-related mortality (aHR = 6.4 [3.9–10.7] (vs. no neurologic infection). Conclusion: Both AIDS and non-AIDS defining neurologic infections continue to occur in PWH resulting in significant morbidity and mortality. Early diagnosis and initiation of ART remain crucial in preventing neurological infections in PWH.

Neuroinflammation coupled with demyelination and neuro-axonal damage in the central nervous system (CNS) contribute to disease advancement in progressive multiple sclerosis (P-MS). Inflammasome activation accompanied by proteolytic cleavage of gasdermin D (GSDMD) results in cellular hyperactivation and lytic death. Using multiple experimental platforms, we investigated the actions of GSDMD within the CNS and its contributions to P-MS. Brain tissues from persons with P-MS showed significantly increased expression of GSDMD, NINJ1, IL-1 beta, and -18 within chronic active demyelinating lesions compared to MS normal appearing white matter and nonMS (control) white matter. Conditioned media (CM) from stimulated GSDMD+/+ human macrophages caused significantly greater cytotoxicity of oligodendroglial and neuronal cells, compared to CM from GSDMD-/- macrophages. Oligodendrocytes and CNS macrophages displayed increased Gsdmd immunoreactivity in the central corpus callosum (CCC) of cuprizone (CPZ)-exposed Gsdmd+/+ mice, associated with greater demyelination and reduced oligodendrocyte precursor cell proliferation, compared to CPZ-exposed Gsdmd-/-animals. CPZ-exposed Gsdmd+/+ mice exhibited significantly increased G-ratios and reduced axonal densities in the CCC compared to CPZ-exposed Gsdmd-/-mice. Proteomic analyses revealed increased brain complement C1q proteins and hexo-kinases in CPZ-exposed Gsdmd-/-animals. [18F]FDG PET imaging showed increased glucose metabolism in the hippocampus and whole brain with intact neurobehavioral performance in Gsdmd-/-animals after CPZ exposure. GSDMD activation in CNS macrophages and oligodendrocytes contributes to inflammatory demyelination and neuroaxonal injury, offering mechanistic and potential therapeutic insights into P-MS pathogenesis.