Central and systemic endotoxin challenges exacerbate the local inflammatory response and increase neuronal death during chronic neurodegeneration

Predictive Value of Inflammation Markers for Frailty in Older Patients with CVD

Background

Chronic inflammation plays a pivotal role in the development of frailty in patients with cardiovascular diseases (CVD). Systemic inflammatory response index (SIRI) has been shown to reflect the overall inflammatory status. This study aimed to investigate the relationship between SIRI and frailty in older patients with CVD, and to develop a nomogram for predicting the risk of frailty in this population.

Methods

A total of 234 older patients with CVD were included. Inflammation markers were derived from routine blood tests, and frailty status was assessed using the FRAIL scale. Clinical and laboratory characteristics were compared between patients with or without frailty. Multivariate logistic regression was employed to identify significant variables for inclusion in the nomogram. The performance of the nomogram, including its discrimination and calibration, was rigorously evaluated.

Results

A total of 98 cases were assigned to the frailty group and 136 to the non-frailty group. Patients in the non-frailty group were generally younger, more likely to have normal kidney function, and better blood pressure control. Frail patients exhibited a higher degree of systemic inflammation compared to non-frail patients (P < 0.05). Age, LDL-C and SIRI were identified as three independent risk factors with significant potential for predicting frailty in CVD patients. Therefore, we constructed a clinical nomogram model for frailty based on age, LDL-C and SIRI. The nomogram for frailty had considerable discriminative and calibrating abilities.

Conclusion

In summary, our study demonstrated a significant association between elevated levels of inflammation markers, particularly SIRI, and an increased risk of frailty. Furthermore, by integrating age, LDL-C and SIRI, we established a nomogram to predict the risk of frailty in older patients with CVD.

Microglial activation and neuroinflammation in acute and chronic cognitive deficits in sepsis

Sepsis is characterised by dysregulated immune responses to infection, leading to multi-organ dysfunction and high rates of mortality. With increasing survival rates in recent years long-term neurological and psychiatric consequences have become more apparent in survivors. Many patients develop sepsis associated encephalopathy (SAE) which encompasses the profound but usually transient neuropsychiatric syndrome delirium but also new brain injury that emerges in the months and years post-sepsis. It is now clear that systemic inflammatory signals reach the brain during sepsis and that very significant neuroinflammation ensues. The major brain resident immune cell population, the microglia, has been implicated in acute and chronic cognitive dysfunction in animal models of sepsis based on a growing number of studies using bacterial endotoxin and in polymicrobial sepsis models such as cecal ligation and puncture. The current review explores the effects of sepsis on the brain, focussing on how systemic insults translate to microglial activation and neuroinflammation and how this disrupts neuronal function and integrity. We examine what has been demonstrated specifically with respect to microglial activation, revealing robust evidence for a role for neuroinflammation in sepsis-induced brain sequelae but less clear information on the extent of the specific microglial contribution to this, arising from findings using global knockout mice, non-selective drugs and treatments that equally target peripheral and central compartments. There is, nonetheless, clear evidence that microglia do become activated and do contribute to brain consequences of sepsis thus arguing for improved understanding of these neuroinflammatory processes toward the prevention and treatment of sepsis-induced brain dysfunction.

Ligature-induced periodontitis in a transgenic mouse model of Alzheimer's disease dysregulates neuroinflammation, exacerbates cognitive impairment, and accelerates amyloid pathology

A growing body of literature has identified periodontal disease among the modifiable risk factors for Alzheimer's disease (AD), but the mechanisms underlying this relationship is unknown. This study investigated this relationship using a ligature-induced preclinical periodontitis (Pd) model in non-transgenic (non-Tg) and 3xTg-AD mice. We found that ligature placement caused significant alveolar bone loss, with 3xTg-AD mice exhibiting exacerbated bone loss, suggesting AD-related genetic risk may amplify disease progression. Pd induced robust local inflammatory gene expression in both genotypes, but 3xTg-AD mice indicated a dysregulated immune response. Cognitive deficits were observed only in Pd-afflicted 3xTg-AD mice, specifically in hippocampus-mediated spatial memory and perirhinal cortex-mediated object recognition memory, while non-Tg mice remained unaffected. Neuroinflammatory responses varied by brain region, with the hippocampus and prefrontal cortex (PFC) showing the most pronounced changes. In these regions, 3xTg-AD mice exhibited significantly altered cytokine gene expression compared to non-Tg mice, particularly at later time points. Synaptic markers revealed vulnerabilities in 3xTg-AD mice, including reduced baseline Syp expression and dysregulated Synpo post-ligature. Pd transiently reduced glutamate receptor gene expression in both genotypes, with non-Tg mice showing persistent changes, potentially linked to preserved memory. Pd also accelerated amyloid-β (Aβ) deposition and sustained neurodegeneration in 3xTg-AD mice. Overall, this study shows that combining Pd and AD-related genetic risk exacerbates inflammation, cognitive impairment, synaptic dysfunction, Aβ pathology, and neurodegeneration. Neither insult alone was sufficient to produce these effects, highlighting the synergistic impact. These findings emphasize the need to explore anti-inflammatory interventions and downstream mechanisms to mitigate the confluence of these diseases.

Impact of COVID-19 on functional, cognitive, neuropsychiatric, and health-related outcomes in patients with dementia: A systematic review

Background

This systematic review analyzes the impact of COVID-19 on dementia patients' functional, cognitive, neuropsychiatric, and health related outcomes. It hypothesizes that dementia patients infected with SARS-CoV-2experience more pronounced deterioration compared to those who are uninfected.

Methods

Research from 01/03/2020 to 07/10/2023 was conducted using Medline, Web of Science, and Embase databases, and adhering to PRISMA guidelines and the PICO framework. The study aimed to determine if SARS-CoV-2 infection is associated with worse outcomes in dementia patients. The protocol is registered in PROSPERO (CRD42022352481), and bias was evaluated using the Newcastle-Ottawa Scale.

Results

Among 198 studies reviewed, only three met the criteria. Chen et al. (2023) identified higher mortality in SARS-CoV-2-infected dementia patients, while Merla et al. (2023) observed faster cognitive decline in infected individuals with increased hospital admissions. Additionally, Cascini et al. (2022) reported an increased risk of infection and significantly elevated mortality in dementia patients, highlighting comorbidities and antipsychotic medication use as key risk factors.

Conclusion

These limited data suggest higher mortality and cognitive decline in dementia patients following COVID-19, underscoring the need for extensive research in this area.

Sex differences in the central and peripheral omega 3 oxylipin response to acute systemic inflammation

High-density lipoprotein (HDL) oxylipins regulate inflammation, and acute systemic inflammation can precipitate cognitive impairment. Females have more HDL and stronger immune responses than males, yet higher dementia risk. Little is known about sex differences in oxylipin responses to inflammatory stimuli and potential crosstalk between acute systemic inflammation and central oxylipin signaling in either sex. In this targeted lipidomics study, we used liquid chromatography with tandem mass spectrometry (LC/MS/MS) to characterize oxylipin profiles in plasma HDL and cerebrospinal fluid (CSF) of male and female rats following an intraperitoneal interleukin-1β (IL-1β)-induced inflammatory challenge to determine whether and how peripheral and central oxylipins respond to acute systemic inflammation in both sexes. We hypothesized that females mount a greater oxylipin response to IL-1β than males and that acute activation of peripheral inflammatory pathways changes central oxylipin concentrations. We found that IL-1β altered the abundance of omega (ω)6 and ω3 oxylipins in plasma HDL and CSF of both sexes. However, IL-1β reduced global concentrations of peripheral and central oxylipins in plasma HDL and CSF, respectively, in female rats only. Reduced oxylipin concentrations in IL-1β-treated females were driven by a loss of anti-inflammatory ω3 eicosapentaenoic acid (EPA)-derived dihydroxyeicosatetraenoic acids (DiHETEs) in plasma HDL and CSF. Interestingly, plasma HDL and CSF concentrations of EPA-derived DiHETEs were only correlated in IL-1β-treated rats, suggesting increased periphery-brain crosstalk during acute systemic inflammation. Overall, the sexually dimorphic responses of peripheral and central oxylipins to acute systemic inflammation provide molecular insight into sex differences in both innate immunity and neuroinflammatory responses.NEW & NOTEWORTHY This study examines previously unexplored sex differences in oxylipin signaling cascade activation in the central nervous system and periphery during the acute phase response. This is the first study to assess and correlate oxylipins in plasma HDL and CSF in males and females following an acute systemic inflammatory challenge. This work showing reduced concentrations of anti-inflammatory ω3 EPA-derived DiHETEs in acutely inflamed females provides molecular insight into sex differences in immunity and inflammation-induced neurological changes.

CA3 Pyramidal Neuron Activation Promotes Cognitive Resilience to Inflammation-Induced Cognitive Inflexibility

AIMS

Cognitive dysfunction represents a prominent symptom in numerous prevalent mental illnesses, with systemic inflammation induced by cytokines recognized as a critical factor contributing to cognitive impairments. However, a significant proportion of individuals exposed to systemic inflammation do not develop cognitive dysfunction; instead, they exhibit adaptive responses to this adverse condition. This study aims to investigate the neural activity patterns within the hippocampus and the potential mechanisms that mediate cognitive resilience, particularly in the context of inflammation.

METHODS

We investigated the effects of systemic IL-1β (Interleukin-1β) on learning, spatial memory, and cognitive flexibility using the Barnes maze test (BMT). We further analyzed specific activity changes in the hippocampus of mice exhibiting cognitive resilience versus susceptibility through immunofluorescence, fiber photometry, and behavioral assessments. Additionally, we employed chemogenetic modulation to explore the role of dCA3 pyramidal neurons in cognitive inflexibility induced by systemic inflammation.

RESULTS

Systemic inflammation induces cognitive inflexibility while leaving learning and memory intact. Notably, dCA3 activity was elevated in cognitively resilient mice compared to their susceptible counterparts. Fiber photometry data revealed higher activity in the dorsal CA3 (dCA3) when the mice approached the previous target quadrant during the reversal stage of BMT. Importantly, the activation of CaMKII+ pyramidal neurons in the dCA3 mitigated cognitive inflexibility induced by systemic IL-1β administration.

CONCLUSIONS

Activation of hippocampal dCA3 neurons, rather than dentate gyrus (DG) neurons, enhances cognitive resilience by improving cognitive flexibility during BMT-related paradigm shifting under sustained inflammation.

Time- and Region-specific Effect of Vortioxetine on Central LPS-induced Transcriptional Regulation of NLRP3 Inflammasome

BACKGROUND

Inflammasome overactivation, multiprotein complexes that trigger inflammatory responses, plays a critical role in Major Depressive Disorder (MDD) pathogenesis and treatment responses. Indeed, different antidepressants alleviate depression-related behaviours by specifically counteracting the NLRP3 inflammasome signalling pathway. The immunomodulatory effects of vortioxetine (VTX), a multimodal antidepressant with cognitive benefits, were recently revealed to counter memory impairment induced by a peripheral lipopolysaccharide (LPS) injection 24 hours (h) postchallenge. The potential link between VTX and NLRP3, along with other inflammasomes, remains un-explored.

METHODS

The potential link between VTX and NLRP3, along with other inflammasomes, remains unexplored. Hence, adult C57BL/6J male mice (n = 73) were fed with a standard or VTX-enriched diet (600 mg/kg of food, 28 days), injected with LPS (830 μg/kg) or saline, and sacrificed 6/24 h post-LPS. At these time-points, transcriptional effects of LPS and VTX on NLRP3, NLRP1, NLRC4, AIM2 (inflammasomes), ASC and CASP1 (related subunits) and NEK7 mediator (NLRP3 regulator) were assessed in dorsal and ventral hippocampal subregions, frontal-prefrontal cortex and hypothalamus, brain regions serving behavioural-cognitive functions impaired in MDD.

RESULTS

Varied expression patterns of inflammasomes were revealed, with long-term NLRP3 and ASC transcriptional changes observed in response to LPS. It was demonstrated that VTX counteracted the LPS-mediated NLRP3 and ASC upregulation in memory-related brain areas like the dorsal hippocampus at 24 h time-point, potentially via regulating NEK7 expression. No VTX-mediated transcriptional effects were observed on other inflammasomes, reinforcing a potentially specific modulation on the NLRP3 inflammasome signalling pathway.

CONCLUSION

Thus, a novel VTX molecular mechanism in modulating the NLRP3 inflammasome in a time- and area-specific manner in the brain was highlighted, with significant clinical implications in treating depression and cognitive impairments.

The Role of Corticosteroids in Non-Bacterial and Secondary Encephalitis

Encephalitis affects 1.9 to 14.3 people per 100,000 each year, and the mortality rate varies but can be up to 40%. After the identification of a particular microorganism in a patient with encephalitis, appropriate antimicrobial therapy should be initiated. Corticosteroid therapy represents a therapeutic option in the treatment of primary central nervous system diseases due to its ability to reduce the inflammatory commitment of CNS and consequently reduce mortality rates regardless of the causative agent of injury. Corticosteroid therapy represents a therapeutic option in the treatment of primary central nervous system diseases. Their use is also recommended in meningitis with autoimmune etiology. While corticosteroids have repeatedly been used as adjunctive treatment in encephalitis of viral etiology, the scientific evidence supporting their effectiveness remains scarce. The use of standard doses recommended by the guidelines seems reasonable as an initial setting, especially when a definitive diagnosis of the causal agent is still awaited. The subsequent adjustment should be personalized based on the individual clinical response.

Maresin-like 1 Ameliorates Neuropathology of Alzheimer's Disease in Brains of a Transgenic Mouse Model

(1) Background: Impeded resolution of inflammation contributes substantially to the pathogenesis of Alzheimer's disease (AD); consequently, resolving inflammation is pivotal to the amelioration of AD pathology. This can potentially be achieved by the treatment with specialized pro-resolving lipid mediators (SPMs), which should resolve neuroinflammation in brains. (2) Methods: Here, we report the histological effects of long-term treatment with an SPM, maresin-like 1 (MarL1), on AD pathogenesis in a transgenic 5xFAD mouse model. (3) Results: MarL1 treatment reduced Aβ overload, curbed the loss of neurons in brains especially cholinergic neurons associated with cleaved-caspase-3-associated apoptotic degeneration, reduced microgliosis and the pro-inflammatory M1 polarization of microglia, curbed the AD-associated decline in anti-inflammatory Iba1+Arg-1+-M2 microglia, inhibited phenotypic switching to pro-inflammatory N1 neutrophils, promoted the blood-brain barrier-associated tight-junction protein claudin-5 and decreased neutrophil leakage in 5xFAD brains, and induced the switch of neutrophils toward the inflammation-resolving N2 phenotype. (4) Conclusions: Long-term administration of MarL1 mitigates AD-related neuropathogenesis in brains by curbing neuroinflammation and neurodegeneration, based on the histological results. These findings provide preclinical leads and mechanistic insights for the development of MarL1 into an effective modality to ameliorate AD pathogenesis.

Ferulic acid mitigated rotenone toxicity -Evoked Parkinson in rat model by featuring apoptosis, oxidative stress, and neuroinflammation signaling

Over time, Parkinson disease (PD) develops as a neurological illness. The goal of this study was to see whether ferulic acid has any neuroprotective benefits on the cerebellum of rats that have Parkinson's disease brought on by rotenone poisoning. A total of twenty-four male albino rats, in good condition, weighed between 200 and 250 g and nine to ten weeks old, were employed in the investigation. The control group received 1 ml of sunflower oil intraperitoneally (i.p.) each day. Rats' motor performance was considerably worse when given rotenone than it was in the control group. Rats given Ferulic Acid (FA) showed a substantial drop in the amount of glutathione (GSH) in the cerebellum. Moreover, the injection of FA resulted in a significant reduction in the optical density (OD) of the immune-positive reaction for α-synuclein, and the area percentage of BCL-2 and NF-kB immunological positive response. FA therapy, surprisingly, enhanced the OD of TH immunopositive response and apoptotic regulators (BCL2) in the cerebellum. Furthermore, FA boosted BCL2 expression, confirming the antiapoptotic effects of FA. Based on these results, FA is probably a good candidate to treat neurodegenerative diseases brought on by long-term exposure to rotenone.

Innate immune memory in chronic HIV and HIV-associated neurocognitive disorders (HAND): potential mechanisms and clinical implications

Although antiretroviral therapy (ART) has dramatically improved the outlook of the HIV/AIDS pandemic, people living with HIV (PLWH) on suppressive therapy are still at higher risk for a range of comorbidities including cardiovascular disease (CVD) and HIV-associated neurocognitive disorders (HAND), among others. Chronic inflammation and immune activation are thought to be an underlying cause of these comorbidities. Many of the factors thought to drive chronic inflammation and immune activation in HIV overlap with factors known to induce trained immunity. Trained immunity is a form of innate immune memory that metabolically and epigenetically reprograms innate immune cells to mount enhanced inflammatory responses upon secondary encounter with unrelated inflammatory stimuli. While this phenotype has been characterized in a variety of disease states in animals and humans, very little is known about its potential contribution to chronic HIV pathogenesis. In this review, a broad overview of innate immune memory in the periphery and the central nervous system (CNS) is provided and the evidence for trained immunity in the context of HIV is considered. In PLWH on ART, this phenotype could contribute to the chronic inflammation and immune activation associated with HIV comorbidities and could complicate HIV cure strategies due to the potential persistence of the phenotype after eradication of the virus. Further research into this immune state in the context of HIV may open the door for new therapeutics aimed at treating HIV comorbidities like HAND.

Neurological Restorative Effects of (-)-Epicatechin in a Model of Gulf War Illness

Gulf War Illness (GWI) afflicts US military personnel who served in the Persian Gulf War. Suspect causal agents include exposure to pyridostigmine (PB), permethrin (PM) and N,N-diethyl-m-toluamide (DEET). Prominent symptoms include cognitive deficits, such as memory impairment. In aging animal models, we have documented the beneficial effect of the flavanol (-)-epicatechin (Epi) on hippocampus structure and related function. Using a rat model of GWI, we examined the effects of Epi on hippocampus inflammation, oxidative stress, mitochondrial dysfunction, cell death/survival pathways, and memory endpoints. Male Wistar rats underwent 3 weeks of exposure to either vehicles or DEET, PM, PB, and stress. Subgroups of GWI rats were then allocated to receive orally 15 days of either water (vehicle) or 1 mg/kg/day of Epi treatment. Object recognition tasks were performed to assess memory. Hippocampus samples were analyzed. Epi treatment yields significant improvements in short- and long-term memory versus GWI rats. Hippocampus oxidative stress and pro-inflammatory cytokine levels showed significant increases with GWI that were largely normalized with Epi becoming comparable to controls. Significant increases in markers of hippocampus neuroinflammation and cell death were noted with GWI and were also largely reduced with Epi. Neuronal survival signaling pathways were adversely impacted by GWI and were partially or fully restored by Epi. Markers of mitochondrial function were adversely impacted by GWI and were fully restored by Epi. In conclusion, in an animal model of GWI, Epi beneficially impacts recognized markers of hippocampus neuroinflammation, oxidative stress, cell survival, neurotoxicity and mitochondrial function leading to improved memory.

Therapeutic approaches to microglial dysfunction in Alzheimer's disease: Enhancing phagocytosis and metabolic regulation

Microglia are essential in neurogenesis, synaptic pruning, and homeostasis. Nevertheless, aging, and cellular senescence may modify their role, causing them to shift from being shields to being players of neurodegeneration. In the aging brain, the population of microglia increases, followed by enhanced activity of genes related to neuroinflammation. This change increases their ability to cause inflammation, resulting in a long-lasting state of inflammation in the brain that harms the condition of neurons. In Alzheimer's Disease (AD), microglia are located inside amyloid plaques and exhibit an inflammatory phenotype characterized by a diminished ability to engulf and remove waste material, worsening the illness's advancement. Genetic polymorphisms in TREM2, APOE, and CD33 highlight the significant impact of microglial dysfunction in AD. This review examines therapeutic approaches that aim to address microglial dysfunction, such as enhancing the microglial capability to engulf and remove amyloid-β clumps and regulating microglial metabolism and mitochondrial activity. Microglial transplanting and reprogramming advancements show the potential to restore their ability to reduce inflammation. Although there has been notable advancement, there are still voids in our knowledge of microglial biology, including their relationships with other brain cells. Further studies should prioritize the improvement of human AD models, establish standardized methods for characterizing microglia, and explore how various factors influence microglial responses. It is essential to tackle these problems to create effective treatment plans that focus on reducing inflammation in the brain and protecting against damage in age-related neurodegenerative illnesses.

Systemic Inflammation Decreases Initial Brain Injury but Attenuates Neurite Extension and Synapse Formation during the Repair of Injured Brains

In this study, we explored the impact of systemic inflammation on initial brain injury and repair processes, including neurite extension and synapse formation. For this purpose, we established a brain injury model by administering adenosine triphosphate (ATP), a component of damage-associated molecular patterns (DAMPs), through stereotaxic injection into the striatum of mice. Systemic inflammation was induced by intraperitoneal injection of lipopolysaccharide (LPS-ip). Bulk RNA-sequencing (RNA-seq) analyses and immunostaining for microtubule-associated protein 2 (MAP2) and tyrosine hydroxylase (TH) showed that LPS-ip led to a reduction in initial brain injury, but inhibited neurite extension into the damaged brain. LPS-ip upregulated expression of defense response genes and anti-apoptotic genes, but decreased expression of genes associated with repair and regeneration. In addition, LPS-ip reduced levels of vGlut1 and PSD95 (markers for excitatory pre and post synapses, respectively), but had little effect on vGAT and gephyrin (markers for inhibitory pre and post synapses, respectively). Taken together, these findings suggest that systemic inflammation reduce initial damage but impede subsequent repair process.

In situ assessment of neuroinflammatory cytokines in different stages of ovine natural prion disease

Introduction

According to the neuroinflammatory hypothesis, a cytokine-mediated host innate immune response may be involved in the mechanisms that contribute to the process of neurodegeneration. Specifically, regarding prion diseases, some experimental murine models have evidenced an altered profile of inflammatory intermediaries. However, the local inflammatory response has rarely been assessed, and never in tissues from different natural models throughout the progression of neurodegeneration.

Methods

The aim of this study was to use immunohistochemistry (IHC) to in situ assess the temporal protein expression of several cytokines in the cerebellum of sheep suffering from various clinical stages of scrapie.

Results and discussion

Clear changes in the expression of most of the assessed markers were observed in the affected sheep compared to the healthy control sheep, and from different stages. In summary, this preliminary IHC study focusing in the Purkinje cell layer changes demonstrate that all cytokines or respective receptors studied (IL-1, IL-1R, IL-2R, IL-6, IL-10R, and TNFαR) except for IFNγR are disease-associated signaling proteins showing an increase or decrease in relation to the progression of clinical disease. In the future, this study will be extended to other inflammatory mediators and brain regions, focusing in particular on the release of these inflammatory mediators by astroglial and microglial populations.

Neonatal overfeeding attenuates microgliosis and hippocampal damage in an infant rat model of pneumococcal meningitis

Background

Pneumococcal meningitis (PM) triggers apoptotic neuronal and progenitor cell death in the hippocampal dentate gyrus (DG), resulting in subsequent cognitive impairment. Microglia play a crucial role in PM-induced hippocampal damage. While the lasting effects of neonatal nutrition on health are well documented, the influence of early-life overfeeding on the host response to neuroinfections remains uncertain. This study aimed to examine whether neonatal overfeeding affects the outcome of PM in the hippocampus (HC).

Material and methods

Overfeeding was induced by adjusting litter size immediately after birth. On the eleventh day of life, rats were intracisternally injected with Streptococcus pneumoniae or saline, followed by euthanasia after 24 hours for brain dissection. Histological analysis evaluated apoptosis in the DG and the extent of inflammatory infiltrate in the hippocampal fissure, while microgliosis was assessed by immunohistochemistry. The hippocampal transcriptome was analyzed using RNAseq, and the mRNA levels of specific inflammatory biomarkers were evaluated via RT-qPCR.

Results

Overfed rats exhibited 40.5% greater body mass compared to their normal-fed counterparts. Intriguingly, PM-induced apoptosis in the DG was 50% lower in overfed rats. This effect was accompanied by significant alterations in the hippocampal transcriptional profile, particularly the lack of activation of the Programmed cell death pathway in overfed infected animals. RT-qPCR analysis of Aif1 and examination of Iba1-immunostained cells revealed mild microgliosis in the HC of infected-overfed animals. This reduced microglial reaction may be attributed to the diminished activation of interferon signaling pathways, as disclosed by the transcriptome analysis, potentially preventing microglial priming. Additionally, evidence of reduced neuroinflammation in overfed rats with PM was observed through the milder activation of pathways associated with Toll-like receptors, interleukins, and chemokine signaling. Furthermore, overfed animals exhibited increased transcription of proinflammatory Il6 and anti-inflammatory Il10 genes, with the latter showing higher expression even in the absence of PM, suggesting a priming effect of overfeeding on hippocampal immune cells.

Conclusion

This study sheds light on the complex interplay between early-life overfeeding, immune response, and neuroprotection in infant rats with PM. The findings demonstrate the neuroprotective impact of early-life overfeeding in the context of PM, linked to the modulation of microglial function.

Inflammaging and Brain Aging

Progress made by the medical community in increasing lifespans comes with the costs of increasing the incidence and prevalence of age-related diseases, neurodegenerative ones included. Aging is associated with a series of morphological changes at the tissue and cellular levels in the brain, as well as impairments in signaling pathways and gene transcription, which lead to synaptic dysfunction and cognitive decline. Although we are not able to pinpoint the exact differences between healthy aging and neurodegeneration, research increasingly highlights the involvement of neuroinflammation and chronic systemic inflammation (inflammaging) in the development of age-associated impairments via a series of pathogenic cascades, triggered by dysfunctions of the circadian clock, gut dysbiosis, immunosenescence, or impaired cholinergic signaling. In addition, gender differences in the susceptibility and course of neurodegeneration that appear to be mediated by glial cells emphasize the need for future research in this area and an individualized therapeutic approach. Although rejuvenation research is still in its very early infancy, accumulated knowledge on the various signaling pathways involved in promoting cellular senescence opens the perspective of interfering with these pathways and preventing or delaying senescence.

Innate immune training restores pro-reparative myeloid functions to promote remyelination in the aged central nervous system

The reduced ability of the central nervous system to regenerate with increasing age limits functional recovery following demyelinating injury. Previous work has shown that myelin debris can overwhelm the metabolic capacity of microglia, thereby impeding tissue regeneration in aging, but the underlying mechanisms are unknown. In a model of demyelination, we found that a substantial number of genes that were not effectively activated in aged myeloid cells displayed epigenetic modifications associated with restricted chromatin accessibility. Ablation of two class I histone deacetylases in microglia was sufficient to restore the capacity of aged mice to remyelinate lesioned tissue. We used Bacillus Calmette-Guerin (BCG), a live-attenuated vaccine, to train the innate immune system and detected epigenetic reprogramming of brain-resident myeloid cells and functional restoration of myelin debris clearance and lesion recovery. Our results provide insight into aging-associated decline in myeloid function and how this decay can be prevented by innate immune reprogramming.

Chronic administration of prebiotics and probiotics ameliorates pathophysiological hallmarks of Alzheimer's disease in a APP/PS1 transgenic mouse model

Introduction: The gut microbiota (MB), although one of the main producers of Aβ in the body, in physiological conditions contributes to the maintainance of a healthy brain. Dysbiosis, the dysbalance between Gram-negative and Gram-positive bacteria in the MB increases Aβ production, contributing to the accumulation of Aβ plaques in the brain, the main histopathological hallmark of Alzheimer's disease (AD). Administration of prebiotics and probiotics, maintaining or recovering gut-MB composition, could represent a nutraceutical strategy to prevent or reduce AD sympthomathology. Aim of this research was to evaluate whether treatment with pre- and probiotics could modify the histopathological signs of neurodegeneration in hippocampal CA1 and CA3 areas of a transgenic mouse model of AD (APP/PS1 mice). The hippocampus is one of the brain regions involved in AD. Methods: Tg mice and Wt littermates (Wt-T and Tg-T) were fed daily for 6 months from 2 months of age with a diet supplemented with prebiotics (a multi-extract of fibers and plant complexes, containing inulin/fruit-oligosaccharides) and probiotics (a 50%-50% mixture of Lactobacillus rhamnosus and Lactobacillus paracasei). Controls were Wt and Tg mice fed with a standard diet. Brain sections were immunostained for Aβ plaques, neurons, astrocytes, microglia, and inflammatory proteins that were evaluated qualitatively and quantitatively by immunofluorescence, confocal microscopy and digital imaging with ImageJ software. Results: Quantitative analyses demonstrated that: 1) The treatment with pre- and probiotics significantly decreased Aβ plaques in CA3, while in CA1 the reduction was not significant; 2) Neuronal damage in CA1 Stratum Pyramidalis was significantly prevented in Tg-T mice; no damage was found in CA3; 3) In both CA1 and CA3 the treatment significantly increased astrocytes density, and GFAP and IBA1 expression, especially around plaques; 4) Microglia reacted differently in CA1 and CA3: in CA3 of Tg-T mice there was a significant increase of CD68+ phagocytic microglia (ball-and-chain phenomic) and of CX3CR1 compared with CA1. Discussion: The higher microglia reactivity could be responsible for their more efficient scavenging activity towards Aβ plaques in CA3 in comparison to CA1. Treatment with pre- and probiotics, modifying many of the physiopathological hallmarks of AD, could be considered an effective nutraceutical strategy against AD symptomatology.

Depressive symptom mediates the association between the number of chronic diseases and cognitive impairment: a multi-center cross-sectional study based on community older adults

Objective

The purpose of this study was to understand the relationship between the multiple chronic conditions (MCC), mental health and cognitive function of older adults in the community, and to propose a hypothesis that depressive symptom mediate the number of chronic diseases and cognitive impairment in older adults.

Method

Participants aged 65 years and older from 35 communities in 14 cities in Guangxi, China were recruited. The residents' depressive symptom (PHQ-9) and cognitive status (AD-8) were evaluated, Chi-square test was used to explore the effects of different socio-demographic characteristics on depressive symptom and cognitive impairment. Pearson correlation analysis and the process model 4 were used to explore the relationship between the number of chronic diseases, depressive symptom and cognitive impairment.

Result

A total of 11,582 older adults were included in our analysis. The rate of MCC reaching 26.53%. Hypertension combined with diabetes accounts for the highest proportion of two chronic diseases (13.2%). Among the combination of three chronic diseases, the highest incidence of coexisting hypertension combined with cervical/lumbar spondylosis, and rheumatoid arthritis (7.1%). In this study, depression symptoms accounted for 12.9% of older adults aged 65 and above, and cognitive impairment accounted for 27.4%. Female, older age, reside in urban areas, lower educational levels, no spouse, live alone, and MCC were risk factors for depressive symptom and cognitive impairment in older adults (P<0.05). Depressive symptom had a mediating effect in the number of chronic diseases and cognitive impairment, and the mediating effect (1.109) accounted for 44.13% of the total effect (0.247).

Conclusion

The mental health of the older adult needs to be taken seriously, and improving depressive symptom can reduce the occurrence of cognitive impairment in older patients with MCC to a certain extent.

Identifying Diagnostic Markers and Constructing Predictive Models for Oxidative Stress in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic disease characterized by inflammation and neurodegeneration of the central nervous system. Despite the significant role of oxidative stress in the pathogenesis of MS, its precise molecular mechanisms remain unclear. This study utilized microarray datasets from the GEO database to analyze differentially expressed oxidative-stress-related genes (DE-OSRGs), identifying 101 DE-OSRGs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicate that these genes are primarily involved in oxidative stress and immune responses. Through protein-protein interaction (PPI) network, LASSO regression, and logistic regression analyses, four genes (MMP9, NFKBIA, NFKB1, and SRC) were identified as being closely related to MS. A diagnostic prediction model based on logistic regression demonstrated good predictive power, as shown by the nomogram curve index and DAC results. An immune-cell infiltration analysis using CIBERSORT revealed significant correlations between these genes and immune cell subpopulations. Abnormal oxidative stress and upregulated expression of key genes were observed in the blood and brain tissues of EAE mice. A molecular docking analysis suggested strong binding potentials between the proteins of these genes and several drug molecules, including isoquercitrin, decitabine, benztropine, and curcumin. In conclusion, this study identifies and validates potential diagnostic biomarkers for MS, establishes an effective prediction model, and provides new insights for the early diagnosis and personalized treatment of MS.

Low-grade systemic inflammation stimulates microglial turnover and accelerates the onset of Alzheimer's-like pathology

Several in vivo studies have shown that systemic inflammation, mimicked by LPS, triggers an inflammatory response in the CNS, driven by microglia, characterized by an increase in inflammatory cytokines and associated sickness behavior. However, most studies induce relatively high systemic inflammation, not directly compared with the more common low-grade inflammatory events experienced in humans during the life course. Using mice, we investigated the effects of low-grade systemic inflammation during an otherwise healthy early life, and how this may precondition the onset and severity of Alzheimer's disease (AD)-like pathology. Our results indicate that low-grade systemic inflammation induces sub-threshold brain inflammation and promotes microglial proliferation driven by the CSF1R pathway, contrary to the effects caused by high systemic inflammation. In addition, repeated systemic challenges with low-grade LPS induce disease-associated microglia. Finally, using an inducible model of AD-like pathology (Line 102 mice), we observed that preconditioning with repeated doses of low-grade systemic inflammation, prior to APP induction, promotes a detrimental effect later in life, leading to an increase in Aβ accumulation and disease-associated microglia. These results support the notion that episodic low-grade systemic inflammation has the potential to influence the onset and severity of age-related neurological disorders, such as AD.

Sleep fragmentation after traumatic brain injury impairs behavior and conveys long-lasting impacts on neuroinflammation

Traumatic brain injury (TBI) causes a prolonged inflammatory response in the central nervous system (CNS) driven by microglia. Microglial reactivity is exacerbated by stress, which often provokes sleep disturbances. We have previously shown that sleep fragmentation (SF) stress after experimental TBI increases microglial reactivity and impairs hippocampal function 30 days post-injury (DPI). The neuroimmune response is highly dynamic the first few weeks after TBI, which is also when injury induced sleep-wake deficits are detected. Therefore, we hypothesized that even a few weeks of TBI SF stress would synergize with injury induced sleep-wake deficits to promote neuroinflammation and impair outcome. Here, we investigated the effects of environmental SF in a lateral fluid percussion model of mouse TBI. Half of the mice were undisturbed, and half were exposed to 5 h of SF around the onset of the light cycle, daily, for 14 days. All mice were then undisturbed 15-30 DPI, providing a period for SF stress recovery (SF-R). Mice exposed to SF stress slept more than those in control housing 7-14 DPI and engaged in more total daily sleep bouts during the dark period. However, SF stress did not exacerbate post-TBI sleep deficits. Testing in the Morris water maze revealed sex dependent differences in spatial reference memory 9-14 DPI with males performing worse than females. Post-TBI SF stress suppressed neurogenesis-related gene expression and increased inflammatory signaling in the cortex at 14 DPI. No differences in sleep behavior were detected between groups during the SF stress recovery period 15-30 DPI. Microscopy revealed cortical and hippocampal IBA1 and CD68 percent-area increased in TBI SF-R mice 30 DPI. Additionally, neuroinflammatory gene expression was increased, and synaptogenesis-related gene expression was suppressed in TBI-SF mice 30 DPI. Finally, IPA canonical pathway analysis showed post-TBI SF impaired and delayed activation of synapse-related pathways between 14 and 30 DPI. These data show that transient SF stress after TBI impairs recovery and conveys long-lasting impacts on neuroimmune function independent of continuous sleep deficits. Together, these finding support that even limited exposure to post-TBI SF stress can have lasting impacts on cognitive recovery and regulation of the immune response to trauma.

Transcriptional pathobiology and multi-omics predictors for Parkinson's disease

Early diagnosis and biomarker discovery to bolster the therapeutic pipeline for Parkinson's disease (PD) are urgently needed. In this study, we leverage the large-scale whole-blood total RNA-seq dataset from the Accelerating Medicine Partnership in Parkinson's Disease (AMP PD) program to identify PD-associated RNAs, including both known genes and novel circular RNAs (circRNA) and enhancer RNAs (eRNAs). There were 1,111 significant marker RNAs, including 491 genes, 599 eRNAs, and 21 circRNAs, that were first discovered in the PPMI cohort (FDR < 0.05) and confirmed in the PDBP/BioFIND cohorts (nominal p < 0.05). Functional enrichment analysis showed that the PD-associated genes are involved in neutrophil activation and degranulation, as well as the TNF-alpha signaling pathway. We further compare the PD-associated genes in blood with those in post-mortem brain dopamine neurons in our BRAINcode cohort. 44 genes show significant changes with the same direction in both PD brain neurons and PD blood, including neuroinflammation-associated genes IKBIP, CXCR2, and NFKBIB. Finally, we built a novel multi-omics machine learning model to predict PD diagnosis with high performance (AUC = 0.89), which was superior to previous studies and might aid the decision-making for PD diagnosis in clinical practice. In summary, this study delineates a wide spectrum of the known and novel RNAs linked to PD and are detectable in circulating blood cells in a harmonized, large-scale dataset. It provides a generally useful computational framework for further biomarker development and early disease prediction.

Microglial response to aging and neuroinflammation in the development of neurodegenerative diseases

ABSTRACT

Cellular senescence and chronic inflammation in response to aging are considered to be indicators of brain aging; they have a great impact on the aging process and are the main risk factors for neurodegeneration. Reviewing the microglial response to aging and neuroinflammation in neurodegenerative diseases will help understand the importance of microglia in neurodegenerative diseases. This review describes the origin and function of microglia and focuses on the role of different states of the microglial response to aging and chronic inflammation on the occurrence and development of neurodegenerative diseases, including Alzheimer's disease, Huntington's chorea, and Parkinson's disease. This review also describes the potential benefits of treating neurodegenerative diseases by modulating changes in microglial states. Therefore, inducing a shift from the neurotoxic to neuroprotective microglial state in neurodegenerative diseases induced by aging and chronic inflammation holds promise for the treatment of neurodegenerative diseases in the future.

Juvenile peripheral LPS exposure overrides female resilience to prenatal VPA effects on adult sociability in mice

Autism spectrum disorder (ASD) exhibits a gender bias, with boys more frequently affected than girls. Similarly, in mouse models induced by prenatal exposure to valproic acid (VPA), males typically display reduced sociability, while females are less affected. Although both males and females exhibit VPA effects on neuroinflammatory parameters, these effects are sex-specific. Notably, females exposed to VPA show increased microglia and astrocyte density during the juvenile period. We hypothesized that these distinct neuroinflammatory patterns contribute to the resilience of females to VPA. To investigate this hypothesis, we treated juvenile animals with intraperitoneal bacterial lipopolysaccharides (LPS), a treatment known to elicit brain neuroinflammation. We thus evaluated the impact of juvenile LPS-induced inflammation on adult sociability and neuroinflammation in female mice prenatally exposed to VPA. Our results demonstrate that VPA-LPS females exhibit social deficits in adulthood, overriding the resilience observed in VPA-saline littermates. Repetitive behavior and anxiety levels were not affected by either treatment. We also evaluated whether the effect on sociability was accompanied by heightened neuroinflammation in the cerebellum and hippocampus. Surprisingly, we observed reduced astrocyte and microglia density in the cerebellum of VPA-LPS animals. These findings shed light on the complex interactions between prenatal insults, juvenile inflammatory stimuli, and sex-specific vulnerability in ASD-related social deficits, providing insights into potential therapeutic interventions for ASD.

Characterization of differences in immune responses during bolus and continuous infusion endotoxin challenges using mathematical modelling

Endotoxin administration is commonly used to study the inflammatory response, and though traditionally given as a bolus injection, it can be administered as a continuous infusion over multiple hours. Several studies hypothesize that the latter better represents the prolonged and pronounced inflammation observed in conditions like sepsis. Yet very few experimental studies have administered endotoxin using both strategies, leaving significant gaps in determining the underlying mechanisms responsible for their differing immune responses. We used mathematical modelling to analyse cytokine data from two studies administering a 2 ng kg-1 dose of endotoxin, one as a bolus and the other as a continuous infusion over 4 h. Using our model, we simulated the dynamics of mean and subject-specific cytokine responses as well as the response to long-term endotoxin administration. Cytokine measurements revealed that the bolus injection led to significantly higher peaks for interleukin (IL)-8, while IL-10 reaches higher peaks during continuous administration. Moreover, the peak timing of all measured cytokines occurred later with continuous infusion. We identified three model parameters that significantly differed between the two administration methods. Monocyte activation of IL-10 was greater during the continuous infusion, while tumour necrosis factor α $ {\alpha} $ and IL-8 recovery rates were faster for the bolus injection. This suggests that a continuous infusion elicits a stronger, longer-lasting systemic reaction through increased stimulation of monocyte anti-inflammatory mediator production and decreased recovery of pro-inflammatory catalysts. Furthermore, the continuous infusion model exhibited prolonged inflammation with recurrent peaks resolving within 2 days during long-term (20-32 h) endotoxin administration.

Narrative Review: Clinical Implications and Assessment of Frailty in Patients With Advanced CKD

Frailty is a multidimensional clinical syndrome characterized by low physical activity, reduced strength, accumulation of multiorgan deficits, decreased physiological reserve, and vulnerability to stressors. Frailty has key social, psychological, and cognitive implications. Frailty is accelerated by uremia, leading to a high prevalence of frailty in patients with advanced chronic kidney disease (CKD) and end-stage kidney disease (ESKD) as well as contributing to adverse outcomes in this patient population. Frailty assessment is not routine in patients with CKD; however, a number of validated clinical assessment tools can assist in prognostication. Frailty assessment in nephrology populations supports shared decision-making and advanced communication and should inform key medical transitions. Frailty screening and interventions in CKD or ESKD are a developing research priority with a rapidly expanding literature base.

Microglia at the blood brain barrier in health and disease

The blood brain barrier (BBB) plays a crucial role in maintaining brain homeostasis by selectively preventing the entry of substances from the peripheral blood into the central nervous system (CNS). Comprised of endothelial cells, pericytes, and astrocytes, this highly regulated barrier encompasses the majority of the brain's vasculature. In addition to its protective function, the BBB also engages in significant crosstalk with perivascular macrophages (MΦ) and microglia, the resident MΦ of the brain. These interactions play a pivotal role in modulating the activation state of cells comprising the BBB, as well as MΦs and microglia, themselves. Alterations in systemic metabolic and inflammatory states can promote endothelial cell dysfunction, reducing the integrity of the BBB and potentially allowing peripheral blood factors to leak into the CNS compartment. This may mediate activation of perivascular MΦs, microglia, and astrocytes, and initiate further immune responses within the brain parenchyma, suggesting neuroinflammation can be triggered by signaling from the periphery, without primary injury or disease originating within the CNS. The intricate interplay between the periphery and the CNS through the BBB highlights the importance of understanding the role of microglia in mediating responses to systemic challenges. Despite recent advancements, our understanding of the interactions between microglia and the BBB is still in its early stages, leaving a significant gap in knowledge. However, emerging research is shedding light on the involvement of microglia at the BBB in various conditions, including systemic infections, diabetes, and ischemic stroke. This review aims to provide a comprehensive overview of the current research investigating the intricate relationship between microglia and the BBB in health and disease. By exploring these connections, we hope to advance our understanding of the role of brain immune responses to systemic challenges and their impact on CNS health and pathology. Uncovering these interactions may hold promise for the development of novel therapeutic strategies for neurological conditions that involve immune and vascular mechanisms.

Radiotherapy induces persistent innate immune reprogramming of microglia into a primed state

Over half of patients with brain tumors experience debilitating and often progressive cognitive decline after radiotherapy treatment. Microglia, the resident macrophages in the brain, have been implicated in this decline. In response to various insults, microglia can develop innate immune memory (IIM), which can either enhance (priming or training) or repress (tolerance) the response to subsequent inflammatory challenges. Here, we investigate whether radiation affects the IIM of microglia by irradiating the brains of rats and later exposing them to a secondary inflammatory stimulus. Comparative transcriptomic profiling and protein validation of microglia isolated from irradiated rats show a stronger immune response to a secondary inflammatory insult, demonstrating that radiation can lead to long-lasting molecular reprogramming of microglia. Transcriptomic analysis of postmortem normal-appearing non-tumor brain tissue of patients with glioblastoma indicates that radiation-induced microglial priming is likely conserved in humans. Targeting microglial priming or avoiding further inflammatory insults could decrease radiotherapy-induced neurotoxicity.

Delirium pathophysiology in cancer: neurofilament light chain biomarker - narrative review

Background Delirium is a debilitating disorder with high prevalence near the end of life, impacting quality of life of patients and their relatives. Timely recognition of delirium can lead to prevention and/or better treatment of delirium. According to current hypotheses delirium is thought to result from aberrant inflammation and neurotransmission, with a possible role for neuronal damage. Neurofilament light chain (NfL) is a protein biomarker in body fluids that is unique to neurons, with elevated levels when neurons are damaged, making NfL a viable biomarker for early detection of delirium. This narrative review summarises current research regarding the pathophysiology of delirium and the potential of NfL as a susceptibility biomarker for delirium and places this in the context of care for patients with advanced cancer.Results Six studies were conducted exclusively on NfL in patients with delirium. Three of these studies demonstrated that high plasma NfL levels preoperatively predict delirium in older adult patients postoperatively. Two studies demonstrated that high levels of NfL in intensive care unit (ICU) patients are correlated with delirium duration and severity. One study found that incident delirium in older adult patients was associated with increased median NfL levels during hospitalisation.Conclusions Targeted studies are required to understand if NfL is a susceptibility biomarker for delirium in patients with advanced cancer. In this palliative care context, better accessible matrices, such as saliva or urine, would be helpful for repetitive testing. Improvement of biological measures for delirium can lead to improved early recognition and lay the groundwork for novel therapeutic strategies.

Dietary inflammatory index and neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are considered a potential threat to mental health. Inflammation predominantly plays a role in the pathophysiology of NPDs. Dietary patterns are widely postulated to be involved in the physiological response to inflammation. This review aims to discuss the literature on how dietary inflammatory index (DII) is related to inflammation and, consequently, NPDs. After comprehensive scrutiny in different databases, the articles that investigated the relation of DII score and various NPDs and psychological circumstances were included. The association between dietary patterns and mental disorders comprising depression, anxiety, and stress proved the role of a proinflammatory diet in these conditions' exacerbation. Aging is another condition closely associated with DII. The impact of proinflammatory and anti-inflammatory diet on sleep quality indicated related disorders like sleep latency and day dysfunctions among the different populations are in relation with the high DII score. The potential effects of genetic backgrounds, dietary patterns, and the gut microbiome on DII are discussed as well. To plan preventive or therapeutic interventions considering the DII, these factors, especially genetic variations, should be considered as there is a growing body of literature indicating the role of personalized medicine in different NPDs. To the best of our knowledge, there is a limited number of RCTs on this subject, so future research should evaluate the causality via RCTs and look for therapeutic interventions with an eye on personalized medicine using information about DII in NPDs.

Susceptibility to acute cognitive dysfunction in aged mice is underpinned by reduced white matter integrity and microgliosis

Age is a significant but heterogeneous risk factor for acute neuropsychiatric disturbances such as delirium. Neuroinflammation increases with aging but the determinants of underlying risk for acute dysfunction upon systemic inflammation are not clear. We hypothesised that, with advancing age, mice would become progressively more vulnerable to acute cognitive dysfunction and that neuroinflammation and neuronal integrity might predict heterogeneity in such vulnerability. Here we show region-dependent differential expression of microglial transcripts, but a ubiquitously observed primed signature: chronic Clec7a expression and exaggerated Il1b responses to systemic bacterial LPS. Cognitive frailty (vulnerability to acute disruption under acute stressors LPS and double stranded RNA; poly I:C) was increased in aged animals but showed heterogeneity and was significantly correlated with reduced myelin density, synaptic loss and severity of white matter microgliosis. The data indicate that white matter disruption and neuroinflammation may be key substrates of the progressive but heterogeneous risk for delirium in aged individuals.

Hippocampal Microglia Activation Induced by Acute Pancreatic Injury in Rats

BACKGROUND

Acute pancreatitis is an inflammation of the pancreatic glandular parenchyma that causes injury with or without the destruction of pancreatic acini. Clinical and experimental evidence suggest that certain systemic proinflammatory mediators may be responsible for initiating the fundamental mechanisms involved in microglial reactivity. Here, we investigated the possible repercussions of acute pancreatitis (AP) on the production of inflammatory mediators in the brain parenchyma focusing on microglial activation in the hippocampus.

METHODS

The acute pancreatic injury in rats was induced by a pancreas ligation surgical procedure (PLSP) on the splenic lobe, which corresponds to approximately 10% of total mass of the pancreas. Blood samples were collected via intracardiac puncture for the measurement of serum amylase. After euthanasia, frozen or paraffin-embedded brains and pancreas were analyzed using qRT-PCR or immunohistochemistry, respectively.

RESULTS

Immunohistochemistry assays showed a large number of Iba1 and PU.1-positive cells in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus of the PLSP group. TNF-α mRNA expression was significantly higher in the brain from PLSP group. NLRP3 inflammasome expression was found to be significantly increased in the pancreas and brain of rats of the PLSP group. High levels of BNDF mRNA were found in the rat brain of PLSP group. In contrast, NGF mRNA levels were significantly higher in the control group versus PLSP group.

CONCLUSION

Our findings suggest that AP has the potential to induce morphological changes in microglia consistent with an activated phenotype.

Periodontitis and Neuropathic Diseases: A Literature Review

Aim

This narrative review aimed at identifying the existing scientific literature investigating periodontitis and neuropathic diseases.

Materials and Methods

A search of the literature published between 2000 and 2022 was carried out in the electronic databases of Scopus and PubMed. Studies in which the eligible articles were mainly published in English were included. Descriptive correlational studies, case-control studies, comparative studies, and cohort studies were also included. The following main keywords were used: "Neuropathic diseases," "Periodontitis," "Alzheimer's disease," and "Porphyromonas gingivalis."

Results

This narrative review found that cognitively impaired persons with severe periodontitis had a higher prevalence and incidence of periodontal diseases than the rest of the population. A significant positive correlation of salivary interleukin (IL)-1beta and immediate recall scores involved in cognition was also evident. It indicates that the most investigated parameter was whether there is any common link between periodontal disease and neurodegeneration. No randomized controlled clinical studies were found in the current literature review.

Conclusions

Based on the literature reviewed, there is currently no strong scientific evidence to support or discourage the cause-effect relationship of periodontal diseases and neurodegenerative diseases.

Microglial Senescence and Activation in Healthy Aging and Alzheimer's Disease: Systematic Review and Neuropathological Scoring

The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aβ, pTAU, and damaged synapses, being pivotal in AD pathogenesis.

Histone deacetylase 3 regulates microglial function through histone deacetylation

As the primary innate immune cells of the brain, microglia respond to damage and disease through pro-inflammatory release of cytokines and neuroinflammatory molecules. Histone acetylation is an activating transcriptional mark that regulates inflammatory gene expression. Inhibition of histone deacetylase 3 (Hdac3) has been utilized in pre-clinical models of depression, stroke, and spinal cord injury to improve recovery following injury, but the molecular mechanisms underlying Hdac3's regulation of inflammatory gene expression in microglia is not well understood. To address this lack of knowledge, we examined how pharmacological inhibition of Hdac3 in an immortalized microglial cell line (BV2) impacted histone acetylation and gene expression of pro- and anti-inflammatory genes in response to immune challenge with lipopolysaccharide (LPS). Flow cytometry and cleavage under tags & release using nuclease (CUT & RUN) revealed that Hdac3 inhibition increases global and promoter-specific histone acetylation, resulting in the release of gene repression at baseline and enhanced responses to LPS. Hdac3 inhibition enhanced neuroprotective functions of microglia in response to LPS through reduced nitric oxide release and increased phagocytosis. The findings suggest Hdac3 serves as a regulator of microglial inflammation, and that inhibition of Hdac3 facilitates the microglial response to inflammation and its subsequent clearing of debris or damaged cells. Together, this work provides new mechanistic insights into therapeutic applications of Hdac3 inhibition which mediate reduced neuroinflammatory insults through microglial response.

Glucose Transport and Utilization in the Hippocampus: From Neurophysiology to Diabetes-Related Development of Dementia

The association of diabetes with cognitive dysfunction has at least 60 years of history, which started with the observation that children with type 1 diabetes mellitus (T1D), who had recurrent episodes of hypoglycemia and consequently low glucose supply to the brain, showed a deficit of cognitive capacity. Later, the growing incidence of type 2 diabetes mellitus (T2D) and dementia in aged populations revealed their high association, in which a reduced neuronal glucose supply has also been considered as a key mechanism, despite hyperglycemia. Here, we discuss the role of glucose in neuronal functioning/preservation, and how peripheral blood glucose accesses the neuronal intracellular compartment, including the exquisite glucose flux across the blood-brain barrier (BBB) and the complex network of glucose transporters, in dementia-related areas such as the hippocampus. In addition, insulin resistance-induced abnormalities in the hippocampus of obese/T2D patients, such as inflammatory stress, oxidative stress, and mitochondrial stress, increased generation of advanced glycated end products and BBB dysfunction, as well as their association with dementia/Alzheimer's disease, are addressed. Finally, we discuss how these abnormalities are accompained by the reduction in the expression and translocation of the high capacity insulin-sensitive glucose transporter GLUT4 in hippocampal neurons, which leads to neurocytoglycopenia and eventually to cognitive dysfunction. This knowledge should further encourage investigations into the beneficial effects of promising therapeutic approaches which could improve central insulin sensitivity and GLUT4 expression, to fight diabetes-related cognitive dysfunctions.

Hyperthermia elevates brain temperature and improves behavioural signs in animal models of autism spectrum disorder

BACKGROUND

Autism spectrum disorders (ASD) are predominantly neurodevelopmental and largely genetically determined. However, there are human data supporting the idea that fever can improve symptoms in some individuals, but those data are limited and there are almost no data to support this from animal models. We aimed to test the hypothesis that elevated body temperature would improve function in two animal models of ASD.

METHODS

We used a 4 h whole-body hyperthermia (WBH) protocol and, separately, systemic inflammation induced by bacterial endotoxin (LPS) at 250 µg/kg, to dissociate temperature and inflammatory elements of fever in two ASD animal models: C58/J and Shank3B- mice. We used one- or two-way ANOVA and t-tests with normally distributed data and Kruskal-Wallis or Mann-Whitney with nonparametric data. Post hoc comparisons were made with a level of significance set at p < 0.05. For correlation analyses, data were adjusted by a linear regression model.

RESULTS

Only LPS induced inflammatory signatures in the brain while only WBH produced fever-range hyperthermia. WBH reduced repetitive behaviours and improved social interaction in C58/J mice and significantly reduced compulsive grooming in Shank3B- mice. LPS significantly suppressed most activities over 5-48 h.

LIMITATIONS

We show behavioural, cellular and molecular changes, but provide no specific mechanistic explanation for the observed behavioural improvements.

CONCLUSIONS

The data are the first, to our knowledge, to demonstrate that elevated body temperature can improve behavioural signs in 2 distinct ASD models. Given the developmental nature of ASD, evidence that symptoms may be improved by environmental perturbations indicates possibilities for improving function in these individuals. Since experimental hyperthermia in patients would carry significant risks, it is now essential to pursue molecular mechanisms through which hyperthermia might bring about the observed benefits.

Ketogenic diet changes microglial morphology and the hippocampal lipidomic profile differently in stress susceptible versus resistant male mice upon repeated social defeat

Psychological stress confers an increased risk for several diseases including psychiatric conditions. The susceptibility to psychological stress is modulated by various factors, many of them being modifiable lifestyle choices. The ketogenic diet (KD) has emerged as a dietary regime that offers positive outcomes on mood and health status. Psychological stress and elevated inflammation are common features of neuropsychiatric disorders such as certain types of major depressive disorder. KD has been attributed anti-inflammatory properties that could underlie its beneficial consequences on the brain and behavior. Microglia are the main drivers of inflammation in the central nervous system. They are known to respond to both dietary changes and psychological stress, notably by modifying their production of cytokines and relationships among the brain parenchyma. To assess the interactions between KD and the stress response, including effects on microglia, we examined adult male mice on control diet (CD) versus KD that underwent 10 days of repeated social defeat (RSD) or remained non-stressed (controls; CTRLs). Through a social interaction test, stressed mice were classified as susceptible (SUS) or resistant (RES) to RSD. The mouse population fed a KD tended to have a higher proportion of individuals classified as RES following RSD. Microglial morphology and ultrastructure were then analyzed in the ventral hippocampus CA1, a brain region known to present structural alterations as a response to psychological stress. Distinct changes in microglial soma and arborization linked to the KD, SUS and RES phenotypes were revealed. Ultrastructural analysis by electron microscopy showed a clear reduction of cellular stress markers in microglia from KD fed animals. Furthermore, ultrastructural analysis showed that microglial contacts with synaptic elements were reduced in the SUS compared to the RES and CTRL groups. Hippocampal lipidomic analyses lastly identified a distinct lipid profile in SUS animals compared to CTRLs. These key differences, combined with the distinct microglial responses to diet and stress, indicate that unique metabolic changes may underlie the stress susceptibility phenotypes. Altogether, our results reveal novel mechanisms by which a KD might improve the resistance to psychological stress.

A Lethal Combination of Delirium and Overcrowding in the Emergency Department

Delirium is a common public health concern that significantly impacts older patients admitted to the Emergency Department (ED). This condition is linked to adverse outcomes such as reduced long-term functionality, higher mortality rates, extended hospital stays, and increased medical costs. The identification of risk factors is crucial for the early recognition and management of delirium in ED patients. Aging, cognitive decline, polypharmacy, and sensory impairment are some of the most common general risk factors described in the literature. Although validated delirium assessment tools already exist, they are not practical for the fast-paced ED environment because of their extended evaluation period or specialized training request. Moreover, clear guidance is needed to select the most suitable tool for detecting delirium, balancing between the accuracy and the swiftness required in an overcrowded, high-stress, and understaffed healthcare setting. This narrative review aims to analyze the updated literature on delirium risk factors in older ED patients and focuses on the methods for better screening, managing, and treating this condition in the ED.

Noteworthy perspectives on microglia in neuropsychiatric disorders

Microglia are so versatile that they not only provide immune surveillance for central nervous system, but participate in neural circuitry development, brain blood vessels formation, blood-brain barrier architecture, and intriguingly, the regulation of emotions and behaviors. Microglia have a profound impact on neuronal survival, brain wiring and synaptic plasticity. As professional phagocytic cells in the brain, they remove dead cell debris and neurotoxic agents via an elaborate mechanism. The functional profile of microglia varies considerately depending on age, gender, disease context and other internal or external environmental factors. Numerous studies have demonstrated a pivotal involvement of microglia in neuropsychiatric disorders, including negative affection, social deficit, compulsive behavior, fear memory, pain and other symptoms associated with major depression disorder, anxiety disorder, autism spectrum disorder and schizophrenia. In this review, we summarized the latest discoveries regarding microglial ontogeny, cell subtypes or state spectrum, biological functions and mechanistic underpinnings of emotional and behavioral disorders. Furthermore, we highlight the potential of microglia-targeted therapies of neuropsychiatric disorders, and propose outstanding questions to be addressed in future research of human microglia.

Role of cytokines and reactive oxygen species in brain aging

Aging is a complex process that produces profound effects on the brain. Although a number of external factors can promote the initiation and progression of brain aging, peripheral and central changes in the immune cells with time, also play an important role. Immunosenescence, which is an age-associated decline in immune function and Inflammaging, a low-grade inflammatory state in the aging brain contribute to an elevation in cytokine and reactive oxygen species production. In this review, we focus on the pro-inflammatory state that is established in the brain as a consequence of these two phenomena and the resulting detrimental changes in brain structure, function and repair that lead to a decline in central and neuroendocrine function.

Ketogenic diet alters microglial morphology and changes the hippocampal lipidomic profile distinctively in stress susceptible versus resistant male mice upon repeated social defeat

Psychological stress confers an increased risk for several diseases including psychiatric conditions. The susceptibility to psychological stress is modulated by various factors, many of them being modifiable lifestyle choices. The ketogenic diet (KD) has emerged as a dietary regime that offers positive outcomes on mood and health status. Psychological stress and elevated inflammation are common features of neuropsychiatric disorders such as certain types of major depressive disorder. KD has been attributed anti-inflammatory properties that could underlie its beneficial consequences on the brain and behavior. Microglia are the main drivers of inflammation in the central nervous system. They are known to respond to both dietary changes and psychological stress, notably by modifying their production of cytokines and relationships among the brain parenchyma. To assess the interactions between KD and the stress response, including effects on microglia, we examined adult male mice on control diet (CD) versus KD that underwent 10 days of repeated social defeat (RSD) or remained non-stressed (controls; CTRLs). Through a social interaction test, stressed mice were classified as susceptible (SUS) or resistant (RES) to RSD. The mouse population fed a KD tended to have a higher proportion of individuals classified as RES following RSD. Microglial morphology and ultrastructure were then analyzed in the ventral hippocampus CA1, a brain region known to present structural alterations as a response to psychological stress. Distinct changes in microglial soma and arborization linked to the KD, SUS and RES phenotypes were revealed. Ultrastructural analysis by electron microscopy showed a clear reduction of cellular stress markers in microglia from KD fed animals. Furthermore, ultrastructural analysis showed that microglial contacts with synaptic elements were reduced in the SUS compared to the RES and CTRL groups. Hippocampal lipidomic analyses lastly identified a distinct lipid profile in SUS animals compared to CTRLs. These key differences, combined with the distinct microglial responses to diet and stress, indicate that unique metabolic changes may underlie the stress susceptibility phenotypes. Altogether, our results reveal novel mechanisms by which a KD might improve the resistance to psychological stress.

Effects of Probiotics on Colitis-Induced Exacerbation of Alzheimer's Disease in AppNL-G-F Mice

Alzheimer's disease (AD) is characterized by progressive cognitive decline and is a leading cause of death in the United States. Neuroinflammation has been implicated in the progression of AD, and several recent studies suggest that peripheral immune dysfunction may influence the disease. Continuing evidence indicates that intestinal dysbiosis is an attribute of AD, and inflammatory bowel disease (IBD) has been shown to aggravate cognitive impairment. Previously, we separately demonstrated that an IBD-like condition exacerbates AD-related changes in the brains of the AppNL-G-F mouse model of AD, while probiotic intervention has an attenuating effect. In this study, we investigated the combination of a dietary probiotic and an IBD-like condition for effects on the brains of mice. Male C57BL/6 wild type (WT) and AppNL-G-F mice were randomly divided into four groups: vehicle control, oral probiotic, dextran sulfate sodium (DSS), and DSS given with probiotics. As anticipated, probiotic treatment attenuated the DSS-induced colitis disease activity index in WT and AppNL-G-F mice. Although probiotic feeding significantly attenuated the DSS-mediated increase in WT colonic lipocalin levels, it was less protective in the AppNL-G-F DSS-treated group. In parallel with the intestinal changes, combined probiotic and DSS treatment increased microglial, neutrophil elastase, and 5hmC immunoreactivity while decreasing c-Fos staining compared to DSS treatment alone in the brains of WT mice. Although less abundant, probiotic combined with DSS treatment demonstrated a few similar changes in AppNL-G-F brains with increased microglial and decreased c-Fos immunoreactivity in addition to a slight increase in Aβ plaque staining. Both probiotic and DSS treatment also altered the levels of several cytokines in WT and AppNL-G-F brains, with a unique increase in the levels of TNFα and IL-2 being observed in only AppNL-G-F mice following combined DSS and probiotic treatment. Our data indicate that, while dietary probiotic intervention provides protection against the colitis-like condition, it also influences numerous glial, cytokine, and neuronal changes in the brain that may regulate brain function and the progression of AD.

The possible role of gut microbiota dysbiosis in the pathophysiology of delirium in older persons

Delirium is a clinical syndrome characterized by an acute change in attention, awareness and cognition with fluctuating course, frequently observed in older patients during hospitalization for acute medical illness or after surgery. Its pathogenesis is multifactorial and still not completely understood, but there is general consensus on the fact that it results from the interaction between an underlying predisposition, such as neurodegenerative diseases, and an acute stressor acting as a trigger, such as infection or anesthesia. Alterations in brain insulin sensitivity and metabolic function, increased blood-brain barrier permeability, neurotransmitter imbalances, abnormal microglial activation and neuroinflammation have all been involved in the pathophysiology of delirium. Interestingly, all these mechanisms can be regulated by the gut microbiota, as demonstrated in experimental studies investigating the microbiota-gut-brain axis in dementia. Aging is also associated with profound changes in gut microbiota composition and functions, which can influence several aspects of disease pathophysiology in the host. This review provides an overview of the emerging evidence linking age-related gut microbiota dysbiosis with delirium, opening new perspectives for the microbiota as a possible target of interventions aimed at delirium prevention and treatment.

Gliosis, misfolded protein aggregation, and neuronal loss in a guinea pig model of pulmonary tuberculosis

Tuberculosis, caused by Mycobacterium tuberculosis infection, is an ongoing epidemic with an estimated ten million active cases of the disease worldwide. Pulmonary tuberculosis is associated with cognitive and memory deficits, and patients with this disease are at an increased risk for Parkinson's disease and dementia. Although epidemiological data correlates neurological effects with peripheral disease, the pathology in the central nervous system is unknown. In an established guinea pig model of low-dose, aerosolized Mycobacterium tuberculosis infection, we see behavior changes and memory loss in infected animals. We correlate these findings with pathological changes within brain regions related to motor, cognition, and sensation across disease progression. This includes microglial and astrocytic proliferation and reactivity. These cellular changes are followed by the aggregation of neurotoxic amyloid β and phosphorylated tau and, ultimately, neuronal degeneration in the hippocampus. Through these data, we have obtained a greater understanding of the neuropathological effects of a peripheral disease that affects millions of persons worldwide.

Postmortem Brains from Subjects with Diabetes Mellitus Display Reduced GLUT4 Expression and Soma Area in Hippocampal Neurons: Potential Involvement of Inflammation

Diabetes mellitus (DM) is an important risk factor for dementia, which is a common neurodegenerative disorder. DM is known to activate inflammation, oxidative stress, and advanced glycation end products (AGEs) generation, all capable of inducing neuronal dysfunctions, thus participating in the neurodegeneration progress. In that process, disturbed neuronal glucose supply plays a key role, which in hippocampal neurons is controlled by the insulin-sensitive glucose transporter type 4 (GLUT4). We investigated the expression of GLUT4, nuclear factor NF-kappa B subunit p65 [NFKB (p65)], carboxymethyllysine and synapsin1 (immunohistochemistry), and soma area in human postmortem hippocampal samples from control, obese, and obese+DM subjects (41 subjects). Moreover, in human SH-SY5Y neurons, tumor necrosis factor (TNF) and glycated albumin (GA) effects were investigated in GLUT4, synapsin-1 (SYN1), tyrosine hydroxylase (TH), synaptophysin (SYP) proteins, and respective genes; NFKB binding activity in the SLC2A4 promoter; effects of increased histone acetylation grade by histone deacetylase 3 (HDAC3) inhibition. Hippocampal neurons (CA4 area) of obese+DM subjects displayed reduced GLUT4 expression and neuronal soma area, associated with increased expression of NFKB (p65). Challenges with TNF and GA decreased the SLC2A4/GLUT4 expression in SH-SY5Y neurons. TNF decreased SYN1, TH, and SYP mRNAs and respective proteins, and increased NFKB binding activity in the SLC2A4 promoter. Inhibition of HDAC3 increased the SLC2A4 expression and the total neuronal content of CRE-binding proteins (CREB/ICER), and also counterbalanced the repressor effect of TNF upon these parameters. This study revealed reduced postmortem human hippocampal GLUT4 content and neuronal soma area accompanied by increased proinflammatory activity in the brains of DM subjects. In isolated human neurons, inflammatory activation by TNF reduced not only the SLC2A4/GLUT4 expression but also the expression of some genes related to neuronal function (SYN1, TH, SYP). These effects may be related to epigenetic regulations (H3Kac and H4Kac status) since they can be counterbalanced by inhibiting HDAC3. These results uncover the improvement in GLUT4 expression and/or the inhibition of HDAC3 as promising therapeutic targets to fight DM-related neurodegeneration.

Leveraging real-world data to improve cochlear implant outcomes: Is the data available?

OBJECTIVES

A small but persistent proportion of individuals do not gain the expected benefit from cochlear implants(CI). A step-change in the understanding of factors affecting outcomes could come through data science. This study evaluates clinical data capture to assess the quality and utility of CI user's health records for data science, by assessing the recording of otitis media. Otitis media was selected as it is associated with the development of sensorineural hearing loss and may affect cochlear implant outcomes.

METHODS

A retrospective service improvement project evaluating the medical records of 594 people with a CI under the care of the University of Southampton Auditory Implant Service between 2014 and 2020.

RESULTS

The clinical records are suitable for data science research. Of the cohort studied 20% of Adults and more than 40% of the paediatric cases have a history of middle ear inflammation.

DISCUSSION

Data science has potential to improve cochlear implant outcomes and improve understanding of the mechanisms underlying poor performance, through retrospective secondary analysis of real-world data.

CONCLUSION

Implant centres and the British Cochlear Implant Group National Hearing Implant Registry are urged to consider the importance of consistently and accurate recording of patient data over time for each CI user. Data where links to hearing loss have been identified, such as middle ear inflammation, may be particularly valuable in future analyses and to inform clinical trials.

Astrocytic Cebpd Regulates Pentraxin 3 Expression to Promote Fibrotic Scar Formation After Spinal Cord Injury

Astroglial-fibrotic scars resulted from spinal cord injury affect motor and sensory function, leading to paralysis. In particular, the fibrotic scar is a main barrier that disrupts neuronal regeneration after spinal cord injury. However, the association between astrocytes and fibrotic scar formation is not yet understood. We have previously demonstrated that the transcriptional factor Cebpd contributes to astrogliosis, which promotes glial scar formation after spinal cord injury. Herein, we show that fibrotic scar formation was decreased in the epicenter region in Cebpd^-/- mice after contusive spinal cord injury and astrocytic Cebpd promoted fibroblast migration through secretion of Ptx3. Furthermore, the expression of Mmp3 was increased under recombinant protein Ptx3 treatment in fibroblasts by observing microarray data, resulting in fibroblast migration. In addition, regulation of Mmp3 occurs through the NFκB signaling pathway by using an irreversible inhibitor of IκBα phosphorylation in pretreated fibroblasts. Of note, we used the synthetic peptide RI37, which blocks fibroblast migration and decreases fibroblast Mmp3 expression in IL-1β-treated astrocyte conditioned media. Collectively, our data suggest that fibroblast migration can be affected by astrocytic Cebpd through the Ptx3/NFκB/Mmp3 axis pathway and that the RI37 peptide may act as a therapeutic medicine to inhibit fibrotic scar formation after spinal cord injury.