Journal of Biomedical Science

Cholinergic neurons in the dorsal motor nucleus of the vagus (DMN) in the brainstem are a key source of efferent vagus nerve fibers that regulate vital functions, including heart rate and inflammation. Whether the integrity of DMN cholinergic neurons is affected during Alzheimer's disease (AD) remains unknown. Here, in female and male mice with experimental AD (5xFAD), which exhibit age-dependent memory impairment, basal forebrain cholinergic neurodegeneration, and microglial alterations, we observe a reduction in cholinergic neuron density in the DMN at 6 and 10 months of age. Furthermore, while an important physiological function of DMN cholinergic signaling, such as suppression of heart rate, is preserved in control mice upon electrical DMN stimulation, the extent of suppression diminishes with age in both female and male 5xFAD mice. In addition, while electrical DMN stimulation lowers pro-inflammatory cytokine levels in control mice subjected to endotoxemia, this anti-inflammatory effect is diminished with age in 5xFAD mice, with females showing earlier dysfunction at 6 months. These results reveal previously unrecognized age-dependent cholinergic deficits in the DMN and disrupted brain - to - periphery vagus nerve circuits in experimental AD. These findings advance our understanding of AD mechanisms and are of interest for the development of conceptually novel therapies.

Whether the nodal vulnerability in dementia is solely represented by changes in cellular abundance or attrition of cellular transcriptomic landscape attribute to that transition in aging brain is yet to uncover with minutiae. To understand this complication, we have analyzed two snRNA-seq data specific to (I) dorsolateral prefrontal cortex (DLPFC): A comprehensive study of cellular profiling among cognitively normal and pathological ageing and dementia (AD) brain, (II) occipital cortex (OC) in the context of Nasu-Hakola disease along with a tissue level bulk RNA-seq data corresponds to temporal cortex. We pinpoint cellular subpopulations their proportional changes within the nodal points and their transcriptomic profiling. In DLPFC we observed alteration of mitochondrial and synaptic maintenance program in the pathological manifestation of disease. In OC we noticed depleted upper layer CUX2 neuron, PVALB and SST neurons on the contrary an enrichment of RORB and LAMP5 neurons with compromised metabolic states in the disease context. Glial populations are marked by representation of fibrous astrocyte, neuronal-supporting subpopulations associated with extracellular matrix remodeling programs. Proportional increment of intermediate myelinating oligodendrocyte and a decrease in mature myelinating subpopulation highlighted a compromised myelin repair attempt. In temporal cortex at tissue level we observed transcriptomic landscape adopted a neuroglial phenotypes in dementia brain. Cell-Chat analysis demonstrated a shift in cellular coordination towards glial population from neuron in NHD brain. A single cell-based drug reprofiling approach identified efatutazone and balaglitazone as broad-spectrum candidates for major cell types in occipital cortex, whereas major actionable biological targets belong to CDK subtypes and proteasome subunits. Overall, our findings imply cellular persistence do not necessarily substantiate molecular preservation, also the coexistence of cellular vulnerability alongside selective remodeling features, present a cellular framework on how to cope up with degenerative changes.

Subtle variations in the activity and signaling of PERK, an endoplasmic reticulum kinase, can shift stress response outcomes. PERK has three commonly occurring exonic single-nucleotide variants frequently inherited together as part of the PERK haplotype B (PERK B), which occurs in 28% of the global population and is associated with several chronic neurodegenerative diseases, although its impact on PERK activity remains controversial. We hypothesized that PERK-B was associated with increased activity, altering stress response and stress tolerance, and that minorly but consistently elevated PERK activity, in combination with additional environmental or genetic risk factors, would lead to adverse outcomes. Comparison of stress response between PERK A, the major PERK haplotype, and PERK B in neuronal cultures using novel knock-in PERK-B mice alongside wild-type PERK A mice revealed differential, transient changes. Following ER stress, astrocyte-containing neuronal cultures, but not neuron-only cultures expressing PERK B exhibited similar levels of eIF2 phosphorylation, the canonical PERK substrate at PERK peak activation point (2h), but showed higher levels at 4 to 6 h, consistent with altered kinetics of PERK signaling. PERK-B neuronal cultures pretreated with a low dose PERK-specific activator exhibited increased vulnerability to N-methyl-D-aspartate-induced death compared to PERK-A neuronal cultures, indicating impaired acquired stress tolerance. Additionally, neuron-astrocyte coculture experiments revealed that the observed difference in acquired stress tolerance was dependent on the astrocyte genotype. The association of PERK-B with transient changes in stress response and reduced stress tolerance with higher vulnerability to cellular stress, albeit transient and small/moderate in size, has clinical relevance based on its potential contribution to the overall genetic vulnerability in neurodegenerative diseases.

Neuroinflammation is a hallmark of several chronic neurodegenerative disorders, including Parkinson's disease (PD) and other synucleinopathies, and is closely associated with microglial activation. The inflammasome adaptor protein apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC) undergoes oligomerization upon inflammasome activation, resulting in the formation of ASC specks. These structures are recognized by microglia as damage-associated molecular patterns (DAMPs), thereby promoting inflammatory signaling. Recent studies have demonstrated that extracellular ASC specks associate with amyloid-{beta} (A{beta}), and that uptake of ASC-A{beta} composites by microglia amplifies pro-inflammatory responses. Although ASC specks have also been shown to potentiate -synuclein (Syn) preformed fibril-induced pathology, their interaction with monomeric Syn and their effects on inflammasome activation remain poorly understood. Here, we co-stimulated murine SIM-A9 microglia with ASC-Syn assemblies and evaluated their effects on NLRP3 inflammasome activation. Electron microscopy revealed a close association between ASC fibrils and Syn monomers. Exposure of microglia to ASC-Syn enhanced NLRP3 inflammasome activation, as evidenced by increased ASC speck formation, caspase-1 activation, and secretion of IL-1{beta} and IL-18, when compared to ASC or Syn alone. In addition, immunohistochemical analyses of post mortem brain tissue from patients with dementia with Lewy bodies demonstrated ASC expression in regions exhibiting Syn pathology and showed ASC co-localization with Syn within Lewy bodies. Collectively, these findings identify ASC-Syn assemblies as potent amplifiers of NLRP3 inflammasome signaling and suggest a mechanism through which they may contribute to sustained neuroinflammation in synucleinopathies.

Huntington disease (HD) is a fatal, neurodegenerative disorder driven by a CAG trinucleotide repeat expansion in the huntingtin (HTT) gene, resulting in neuronal toxicity and brain atrophy, initially in the most vulnerable brain region striatum and expanding to the cortex and other brain regions along disease progression. While cell-autonomous mechanisms within neurons have been extensively characterized, how brain waste clearance pathways at the brain's borders change during disease progression remains poorly understood. In this study, we investigated the structural and functional adaptations of border-associated macrophages (BAMs) in the zQ175DN knock-in mouse model of HD. Immunohistochemical analysis revealed an age-dependent, selective reduction in the CD206 Lyve1 subset of leptomeningeal BAMs in 16-month-old zQ175DN mice, which tightly correlated with a profound impairment in cerebrospinal fluid (CSF) flow velocity and perivascular influx. To determine whether BAMs actively drives this CSF flow, we selectively depleted these populations of macrophages in 10-month-old zQ175DN mice via intracerebroventricular (i.c.v.) injection of clodronate liposomes (CLO). Chemical ablation of BAMs significantly exacerbated global CSF dynamic impairment, indicted by decreasing CSF fluorescent tracer distribution across perivascular parenchymal channels. Crucially, this CSF flow failure resulted in a marked accumulation of extranuclear mutant huntingtin (mHTT) aggregates in the zQ175DN HD mouse brain, while intranuclear inclusions were not significantly altered. Furthermore, BAMs depletion did not alter microglial or astrocytic gliosis in the brain, demonstrating that the exacerbation of mHTT load is a byproduct of brain waste clearance dysfunction. Together, our results indicate that BAMs are non-redundant regulators of CSF flow dynamics at the brain borders, offering a unique non-neuronal therapeutic target to combat HD.

Extracellular cold-inducible RNA-binding protein (eCIRP) is a crucial neuroinflammatory mediator in ischemic stroke and alcohol-induced memory impairment. We have recently discovered that amyloid{beta} causes microglia to release eCIRP, prompting us to investigate its role in Alzheimer's disease (AD). We found that eCIRP levels were significantly elevated in the cerebrospinal fluid (CSF) and plasma of AD patients compared with age-matched non-AD subjects, as well as in hTau.P301S mice (a model of AD tauopathy) compared with wildtype control mice. Plasma eCIRP strongly correlated with astrocyte activation marker glial fibrillary acidic protein (GFAP) in AD patients. eCIRP induced neurotoxic astrocyte-specific genes and astrocyte release of proinflammatory and neurotoxic factors in C8-D1a cells, primary murine astrocytes and intracerebroventricular eCIRP-injected C57BL/6 mice brains. In particular, eCIRP increased Complement 3, an astrocytic marker involved in neuroinflammation-associated neurodegeneration. Primary astrocytes from TREM-1 knockout mice were resistant to eCIRP induction of neurotoxic astrocytes. eCIRP increased TREM-1 expression and activation in astrocytes. Blocking CIRP/TREM-1 interaction using peptide M3, effectively attenuated eCIRP's induction of neurotoxic astrocytes. Thus, eCIRP strongly correlates with astrocyte reactivity in AD patients, and eCIRP induces neurotoxic astrocytes via TREM-1, which is attenuated by M3, suggesting a novel therapeutic opportunity to target neurotoxic astrocytes in AD.

Microglial activation in response to aggregated -synuclein (-syn) accumulation is a pathological hallmark of Parkinson disease (PD). A distinct activated microglial state, disease-associated microglia (DAM), has been identified across multiple neurodegenerative disorders, including PD. However, the transcriptional and epigenetic programs governing DAM differentiation remain unclear. Here, we show that neuronal -syn overexpression drives progressive microglial state transitions toward DAM, accompanied by increased phagocytic activity and enhanced cytokine and chemokine production. Integrative transcriptomic and chromatin accessibility analyses reveal a hierarchical NF-{kappa}B--AP-1--IRF regulatory program underlying these state transitions. Microglial NF-{kappa}B p65 (RelA) or IRF4 deficiency impairs microglial progression toward DAM, with RelA and IRF4 governing early microglial activation and subsequent DAM differentiation, respectively. Enrichment of NF-{kappa}B, AP-1, and IRF motifs in DAM in human PD supports conservation of this regulatory program across species. Together, our findings establish RelA and IRF4 as sequential, stage-specific regulators that coordinate -syn-induced DAM differentiation in PD.

Herpes zoster (HZ), caused by varicella zoster virus (VZV) reactivation, is common in older adults with declining cell-mediated immune protection. A modestly efficacious live attenuated (ZVL) and a highly efficacious recombinant adjuvanted (RZV) zoster vaccine protect against HZ. To uncover the mechanism(s) associated with the superior efficacy of RZV, we developed a controlled human infection model consisting of intradermal administration of attenuated vOka VZV to older adults previously vaccinated with RZV or ZVL. Infiltration of VZV-specific CD4+ and CD8+ T cell clonotypes at the infection site was quicker and higher in RZV than ZVL recipients [≥]5 years post-immunization due to the persistence of RZV-induced gE-reactive CD4+ and CD8+ T cell clonotypes in blood. High CD4+ cytotoxic T lymphocyte frequencies in blood on Day 1 post-inoculation predicted control of VZV replication. Persistence of circulating RZV-induced CD4+ and CD8+ CTL and rapid migration to sites of VZV replication are potential mechanisms underlying durable protection against HZ.

Background: Low-density lipoprotein cholesterol (LDL-C) is an established risk factor for atherosclerotic cerebrovascular disease, but its effects on the cerebral microcirculation are poorly defined. We investigated whether LDL-C is associated with pericyte dysfunction in acute ischemic stroke (AIS) and explored underlying mechanisms. Methods: Serum soluble platelet-derived growth factor receptor-{beta} (sPDGFR{beta}) was measured in two independent AIS cohorts (n=97 and n=86). Cerebral pericyte transcriptional responses to LDL-C were analyzed by single-cell RNA sequencing in Apoe-knockout mice fed control or high-fat diet (n=4 [male/female: 2/2]/group), and cultured human brain pericytes were exposed to purified human LDL cholesterol with or without N-acetyl-L-cysteine. Results: Higher serum sPDGFR{beta} was associated with greater neurological deficit and circulating neurofilament light chain. LDL-C positively correlated with sPDGFR{beta} in both clinical cohorts. High-fat diet induced coordinated suppression of type-I interferon pathways, and a positive shift in reactive oxygen species-related transcriptional programs in mouse pericytes; exploratory sex-by-diet analyses suggested larger transcriptional responses in females. In cultured human pericytes, LDL-C induced oxidative-stress, lipid-handling, and ferroptosis-associated transcriptional programs while suppressing type-I interferon signaling. Cross-species enrichment analysis showed that LDL-C-induced and -repressed signatures in cultured pericytes aligned with the sex-by-diet interaction in Apoe-knockout mice. LDL-C also reduced cell-surface PDGFR{beta} and increased sPDGFR{beta} release in cultured pericytes, which were significantly attenuated by N-acetyl-L-cysteine, whereas LDH activity increased numerically but not significantly. Conclusions: Clinical and experimental findings support an LDL-pericyte axis linking atherogenic lipid stress to cerebral microvascular dysfunction, with possible sex-dependent modulation of oxidative stress and type-I interferon signaling as potential mechanisms.

Mosquito-borne orthoflaviviruses pose a significant threat to human and animal health worldwide. In Europe, West Nile (WNV), Usutu (USUV) and Bagaza (BAGV) viruses have expanded their geographic distribution and are detected with increasing frequency. Following the emergence of BAGV in 2021, we investigated the circulation dynamics and genomic diversity of orthoflaviviruses in southern Portugal, where their epidemiology remains poorly understood. Active Orthoflavivirus surveillance was conducted in birds and mosquitoes during 2021-2023 using serological and molecular assays, complemented by viral genome sequencing and phylogenomic analyses. Viral RNA was detected in 3.5% (41/1,171) of birds, while seroneutralization assays identified an overall seroprevalence of 55.3% (503/910). WNV RNA (lineage-1, strains WMed-1.2 and WMed-1.3) was detected annually in resident birds, including Alectoris rufa, Cyanopica cooki and Garrulus glandarius (1.5%, 18/1,171), and in Culex univittatus mosquitoes (0.8%, 2/255). Together with a WNV-specific seroprevalence of 28.5% (259/910) in birds, these findings support sustained local circulation. USUV RNA (Africa 3.1 sub-lineage) was detected in A. rufa in 2021 and 2023 (0.2%, 2/1,171), but seroprevalence was low (1.3%, 8/623), consistent with intermittent circulation. BAGV RNA (genotype-2) was detected only during the 2021 outbreak in A. rufa and Emberiza calandra (1.8%, 21/1,171), although BAGV-specific antibodies (6.6%, 60/910) were detected for up to two years after the outbreak, suggesting continued exposure or low-level circulation. Overall, our findings reveal contrasting circulation dynamics of orthoflaviviruses in southern Portugal. Sustained WNV circulation implies the need to strengthen avian and human surveillance in Portugal to better assess its public health risk, while the sporadic detection of USUV and BAGV underscores the value of long-term, integrated One Health surveillance for improving early warning and preparedness for emerging mosquito-borne diseases.

Objective: Autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) frequently present as overlap syndromes, characterized by shared sexual dimorphism and elevated intestinal Veillonella dispar (V. dispar) abundance, yet exhibiting distinct hallmark pathological manifestations. This study aimed to elucidate the shared pathogenesis, phenotypic differentiation mechanisms and sex-specific predisposition of AIH and PBC induced by V. dispar. Methods: Clean-grade and germ-free (GF) mice were employed to establish AIH and PBC models. Model induction involved oral gavage of V. dispar and intraperitoneal injection of either liver-specific antigen S100 (for AIH) or a pyruvate dehydrogenase complex E2 subunit (PDC-E2) mimetic peptide (for PBC). Single-cell RNA sequencing, metabolomics, transmission electron microscopy, western blotting, and flow cytometry were utilized to elucidate the underlying mechanisms. Results: V. dispar successfully induced autoimmune liver disease-like features in mice, characterized by significant intrahepatic B cell infiltration. Mechanistically, V. dispar caused systemic arginine reduction, leading to intrinsic apoptosis of gonadal stromal cells and a subsequent reduction in testosterone. This decreased testosterone weakened its inhibitory effect on B cell activating factor (BAFF) secretion, thereby amplifying B cell-mediated immune responses. Furthermore, in the presence of S100 or PDC-E2 mimetic peptide, V. dispar also facilitated Th17 cell activation, which guided the phenotypic differentiation into AIH or PBC, respectively. Consistent with these findings, our clinical observations revealed that patients with AIH and PBC tended to harbor enriched V. dispar, along with lower serum arginine and testosterone. In addition, elevated serum levels of BAFF and IL-17 were also observed in these patients. Conclusion: V. dispar induces reduced testosterone levels and upregulation of BAFF, leading to intrahepatic B cell expansion, which serves as the common pathogenic basis for AIH and PBC. The presence of S100 and PDC-E2 subsequently drives further maturation of these expanded B cells and promotes Th17 cell activation, thereby determining the phenotypic divergence between AIH and PBC.

Traumatic brain injury (TBI) is one of the world's leading causes of death and disability and a major risk factor for dementias. The primary dementia associated with TBI is chronic traumatic encephalopathy (CTE), a neurodegenerative disease classified as a tauopathy, in which toxic tau molecules lead to disease pathologies and degeneration. The processes that lead to tauopathy and subsequent dementia after TBI remain unclear. Here, we built upon the finding that seizures after TBI may be a mechanism leading to tauopathy, by dissecting the functions of the metabotropic glutamate receptor 5 - cellular prion protein (mGluR5-PrPC) pathway. We delivered TBI to larval in a blast paradigm, and quantified aggregation of Tau via a genetically-encoded Tau-GFP fusion reporter. Zebrafish larvae lacking prp2 (homolog of mammalian cellular Prion Protein, PrPC) displayed a 168% increase in post-traumatic seizures activity after TBI. An mGluR5 agonist (CHPG) reduced post-traumatic seizures, whereas an mGluR5 antagonist (MPEP) increased post-traumatic seizures. Moreover, agonizing mGluR5 reduced tau aggregation and antagonizing mGluR5 increased tau burden. Larvae seizing from convulsants, rather than TBI, were treated with CHPG/MPEP and provided a similar pattern of outcomes, suggesting seizures may be a factor needed for mGluR5 activity to influence tau aggregation. The PrPC-mGluR5 pathway is proposed as one candidate pathomechanism linking TBI to subsequent seizures and tauopathy, and thus it warrants investigation as a target for prophylactic interventions.

Huntington&'s disease (HD) is characterized by progressive accumulation of mutant huntingtin (mHTT), neurodegeneration and motor dysfunction. Increasing evidence implicates impaired glymphatic function and loss of perivascular aquaporin 4 (AQP4) polarization in HD, suggesting that defective brain waste clearance may contribute to disease pathogenesis. Whether restoration of AQP4&-mediated glymphatic transport can ameliorate HD pathology remains unknown. We tested whether genetic restoration of AQP4 improves glymphatic function and HD&-associated phenotypes in heterozygous zQ175 knock-in mice. At 2 months of age, premanifest zQ175 mice received a single retro-orbital injection of BBB-penetrant AAV9&-PHP.eB encoding the AQP4 (M1 isoform). Glymphatic transport was assessed by intracisternal injection of fluorescent BSA 647 and quantification of parenchymal influx and drainage to the deep cervical lymph nodes. Perivascular AQP4 localization, mHTT aggregation, gliosis, DARPP32 immunoreactivity, CSF neurofilament light chain (NfL) and total Tau, structural brain volumes by 11.7T MRI, and motor behavior were assessed longitudinally through 12 months of age. AAV9&-PHP.eB&-AQP4 produced widespread brain expression and restored perivascular AQP4 localization in the striatum and cortex of zQ175 mice. AQP4 overexpression significantly increased glymphatic tracer influx into brain parenchyma and BSA-647 drainage to the deep cervical lymph nodes. At 12 months, AQP4 restoration reduced CSF NfL and total Tau concentrations, mHTT aggregate number and mean aggregate size, and striatal Iba1 positive microglia and GFAP-positive astrocytes (P < 0.05). AQP4 overexpression also preserved striatal DARPP32 immunoreactivity and significantly attenuated striatal atrophy measured by MRI. Female zQ175 mice showed improved balance-beam performance and locomotor activity, while effects on motor performance in males did not reach statistical significance. AQP4 overexpression attenuated body-weight loss in both sexes. No detectable structural, behavioral or body-weight abnormalities were observed following sustained AQP4 overexpression in wild-type mice. In summary, restoration of AQP4 enhances glymphatic transport and is associated with reduced proteopathic, neuroinflammatory and neurodegenerative phenotypes in zQ175 HD mice. These findings provide proof-of-concept that impaired glymphatic function is a modifiable component of HD pathology and support AQP4&-mediated restoration of brain waste clearance pathways as a potential disease-modifying therapeutic strategy.

Experimental models of Parkinson's disease (PD) traditionally involve direct perturbations of the functioning of dopamine (DA) neurons. However, PD is increasingly recognized as multifactorial in origin and involving both cell-autonomous vulnerability factors and non-cell-autonomous triggers including inflammatory signals deriving from bacterial or viral infections. Notably, genes associated with early-onset familial PD as PRKN (Parkin) and PINK1, are ubiquitously expressed and have been implicated in immune regulation, further supporting a role for inflammation in disease etiology. In the present study, we tested the hypothesis that alternate Polyinosinic:polycytidylic acid (Poly(I:C)), mimicking viral infection, and lipopolysaccharides (LPS), mimicking bacterial infection, may induce sufficient brain inflammation to impair the DA system in Parkin-deficient mice and recapitulate some of the systemic features of PD. We developed a protocol with alternating Poly(I:C) and LPS, inducing acute peripheral inflammation in both genotypes, with consistent body weight loss and an increase of fecal lipocalin-2. Modest levels of neuroinflammation were present six months after the treatment, with higher levels of the microglial marker Iba1 in the dorsal striatum and reduced levels of the astrocyte marker GFAP in the mesencephalon, potentially indicating reduced neuronal support in the longer term. Finally, we find that this alternating Poly(I:C)/LPS treatment does not induce dopaminergic denervation or motor dysfunctions, even in Parkin KO mice. Taken together, our findings suggest that repeated short-term exposure to pathogen-derived signals is insufficient to induce DA system impairment in young adult Parkin deficient mice. Instead, induction of PD-like pathology may require a convergence of factors, including a prolonged or recurrent inflammatory burden, aging, genetic susceptibility, and potentially additional environmental or cellular stressors, that together create a pathogenic "perfect storm". Thus, in its current form, the paradigm developed in the present study should not be regarded as a fully representative model of PD. Rather, it provides proof of concept that temporally alternating inflammatory stimuli can shape non-motor symptom-like phenotypes and underscores the need for future animal model research to incorporate interacting risk factors, disease duration, and age-dependent vulnerability.

Oligodendrocyte (OLG) injury and loss are increasingly recognized as major determinants of demyelination and remyelination failure in multiple sclerosis (MS), alongside conventional immune-mediated processes. However, the mechanism underlying OLG injury and remyelination failure remains incompletely understood. Astrocyte-oligodendrocyte interactions mediated by Connexin (Cx)-43-Cx47 gap junction (GJ) communication and leukemia inhibitory factor (LIF)-LIFR/gp130 signaling are critical for oligodendroglial survival, homeostasis, and myelination. Despite their established role, how these pathways are altered during neuroinflammatory diseases remains unclear. To address this, we integrated a murine {beta}-coronavirus (RSA59)-induced in vivo model with enriched primary oligodendrocyte precursor cell (OPC) and mature OLG cultures to investigate the effect of RSA59 infection on OLGs, Cx47-mediated GJ communication, and LIF-LIFR/gp130 Signaling. We observed that RSA59 directly targets oligodendroglial lineage cells, including OPCs and mature OLGs, and induces apoptosis in mature OLGs. Despite increased OPC abundance, RSA59 infection reduces the expression of mature and myelinating markers CNPase and MBP, raising the possibility of impaired oligodendrocyte maturation and myelination. RSA59 infection also differentially regulates Cx47-mediated GJ communication and LIF-LIFR/gp130 signaling, crucial for OLG survival and homeostasis. Furthermore, our studies demonstrate that extracellular signal-regulated kinase (ERK), a downstream effector of LIF signaling, phosphorylates the Cx47 C-terminal domain (Cx47CT) at Serine-372 residue, identifying a previously unreported mechanism. Collectively, these findings reveal that RSA59 infection disrupts interconnected oligodendroglial communication and survival pathways, providing mechanistic insights into virus-induced chronic demyelination pathology. The study further identifies Cx47-mediated GJ communication and LIF-LIFR/gp130 signaling as crucial therapeutic targets, and highlights ERK-dependent Cx47CT phosphorylation as a potential regulatory mechanism.

TAR DNA-binding protein-43 (TDP-43) alterations are a key hallmark of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerative disorders. Increasing evidence links these conditions to viral infections, but it is not known if and how viral pathogens may be affected by disease-associated TDP-43. We found that ALS/FTD-linked forms of human TDP-43 prevent infection by herpes simplex virus type-1 (HSV-1), a common neurotropic virus. This cell-autonomous protective effect was conserved across different TDP-43 mutations, sporadic ALS, and C9ORF72-ALS, in neural and non-neural cell types, and in patient-derived cells and animal models. In addition to restricting infection, TDP-43 mutation prevented inflammatory and cell stress-related responses to HSV-1 exposure. TDP-43 knockdown but not overexpression was sufficient to protect cells from HSV-1 infection, implicating a loss-of-function mechanism. Neurons with TDP-43 mutation had disruptions in adhesion-related pathways and, accordingly, had reduced early-stage viral binding and entry. Further analyses revealed alternative RNA splicing and impairment of focal adhesion kinase (FAK/PTK2), a key mediator of cell-adhesion pathways. Inhibition of FAK was sufficient to decrease HSV-1 infection, and genetic enhancement of functional but not inactive FAK promoted infectivity in cells with TDP-43 mutation. Together, these data indicate that TDP-43 affects virus-host interactions by influencing adhesion pathways required for viral infection.

Midbrain organoids (MOs) can be powerful tools to study brain diseases, yet one shortcoming is the lack of microglia due to their mesodermal developmental origin. Previous studies have incorporated iPSC-derived microglia (iMG), but their immature phenotype restricts the applicability to model age-related neuroinflammatory processes relevant to diseases such as Parkinson's Disease (PD). To address this, we have incorporated MOs with human postmortem PD microglia, iPSC-derived microglial progenitors (iMP), and iMG. Postmortem microglia had a higher infiltration capacity resulting in more microglia per organoid, while iMP had a higher migration capacity reaching the core of the organoid. Compared to iPSC-derived cells, more infiltrated postmortem PD microglia were HLA Class II positive and CD68 positive. This novel approach of integrating postmortem microglia into organoids opens new avenues for modelling age-related neuroinflammatory diseases.Ongoing methodological advancements like our study will offer the field a valuable tool for studying human microglia biology in both health and disease.

Apigenin is an abundant, bioactive phytochemical with reported therapeutic potential and neuroprotective effects in a variety of age-related disease models. However, the extent to which apigenin may promote healthspan and protect against neurodegeneration-associated proteotoxicity has not been thoroughly investigated, and the biological processes/mechanisms that underlie its protective effects remain unclear. To determine if apigenin increases healthspan, we performed lifespan assays in conjunction with measures of aging-relevant physiological function in wild-type C. elegans. We found that chronic exposure to apigenin extended median lifespan and improved multiple readouts of healthspan, including pharyngeal pumping, locomotor activity, and age-related macromolecular damage accumulation. Additional analyses of transgenic reporter strains and transcriptomic profiling (RNA-seq) indicated that apigenin primarily modulated redox-sensitive stress signaling and pathways associated with cellular homeostasis in aging animals. Finally, in transgenic C. elegans strains expressing the pathological Alzheimer's disease-associated proteins amyloid-beta or tau, we found that apigenin had similar beneficial effects on lifespan, healthspan, and proteotoxicity-associated functional impairments. Together, our results support apigenin as a potential healthspan-promoting intervention that acts in part through reductions in oxidative stress-associated signaling, with beneficial effects that extend to models of Alzheimer's disease-associated proteotoxicity.

Microglia are essential immune cells of the brain parenchyma which are responsible for maintaining homeostasis and responding to brain injury. When activated, they induce immune signaling and become phagocytic. In the context of neurodegenerative diseases, they exhibit both pro- and anti-inflammatory properties. Human endogenous retroviruses (HERVs) are the remnants of ancient retroviral germline infections that integrated into the human genome, and their expression has been directly linked to microglial-mediated neurodegenerative diseases. Despite this, HERV expression is not consistently included in analyses characterizing microglia. Investigating the function of microglia across different diseases is critical for elucidating mechanisms of disease progression and for the development of effective therapeutic interventions. Approaches to studying microglia include isolation from post-mortem brain tissues, differentiation from peripheral blood monocytes or differentiation of induced pluripotent stem cells (iPSC). Ex vivo brain derived microglia (BdMG) are considered most physiologically relevant, but constraints including the unpredictable timing of availability, labor-intensive protocols, and low yields reduce their practicality. Existing alternatives are iPSC-derived microglia (iMG) and monocyte-derived microglia (MDMi) models that circumvent sample accessibility and scalability issues. Here, we explored the transcriptome and proteome of these three microglia sources and identified a common microglia surface marker expression profile, establishing that MDMi and iMG exhibit similar phenotypes relative to BdMG. We also identified a common HERV expression profile across BdMG, iMG and MDMi, indicating deeper similarities across different sources. Altogether, our findings indicate that given the phenotypic similarities of the 2 models, MDMi represent a practical and reliable model for investigating microglial function with iMG models serving for more molecular based approaches, such as CRISPRa/i.

Behavioral disinhibition is a hallmark symptom of behavioral variant frontotemporal dementia (bvFTD). There is no cure or strategy to slow progression, mainly due to little understanding of how disinhibition occurs and the mechanisms underlying self-control. To date, disinhibition has not been demonstrated in an FTD model. We designed a paradigm to assess disinhibition, separating general cognitive capacity, and found that aged mutant mice display increased impulsive choice but have intact cognition, suggestive of early-mid- stage bvFTD-associated symptoms. Further, the neural mechanisms underlying self-control are dissociable from impulsive choice; CaMKIIlower case Greek alpha- and somatostatin-expressing neurons in the medial prefrontal cortex, but not the classical anterior cingulate cortex, were activated during self-control. Together, we demonstrate behavioral disinhibition in mutant mice and identified specific regions and cell types that underlie self-control. This paradigm is viable for future work dissecting neural circuits underling impulsive choice and self-control behavior in bvFTD and other neurological conditions.