Acute systemic inflammation exacerbates neuroinflammation in Alzheimer's disease: IL-1β drives amplified responses in primed astrocytes and neuronal network dysfunction

Short-term high fat diet impairs memory, exacerbates the neuroimmune response, and evokes synaptic degradation via a complement-dependent mechanism in a mouse model of Alzheimer's disease

Alzheimer's Disease (AD) is a neurodegenerative disease characterized by profound memory impairments, synaptic loss, neuroinflammation, and hallmark pathological markers. High-fat diet (HFD) consumption increases the risk of developing AD even after controlling for metabolic syndrome, pointing to a role of the diet itself in increasing risk. In AD, the complement system, an arm of the immune system which normally tags redundant or damaged synapses for pruning, becomes pathologically overactivated leading to tagging of healthy synapses. While the unhealthy diet to AD link is strong, the underlying mechanisms are not well understood in part due to confounding variables associated with long-term HFD which can independently influence the brain. Therefore, we experimented with a short-term diet regimen to isolate the diet's impact on brain function without causing obesity. This project investigated the effect of short-term HFD on 1) memory, 2) neuroinflammation including complement, 3) AD pathology markers, 4) synaptic markers, and 5) in vitro microglial synaptic phagocytosis in the 3xTg-AD mouse model. Following the consumption of either standard chow or HFD, 3xTg-AD and non-Tg mice were tested for memory impairments. In a separate cohort of mice, levels of hippocampal inflammatory markers, complement proteins, AD pathology markers, and synaptic markers were measured. For the last set of experiments, BV2 microglial phagocytosis of synapses was evaluated. Synaptoneurosomes isolated from the hippocampus of 3xTg-AD mice fed chow or HFD were incubated with equal numbers of BV2 microglia. The number of BV2 microglia that phagocytosed synaptoneurosomes was tracked over time with a live-cell imaging assay. Finally, we incubated BV2 microglia with a complement receptor inhibitor (NIF) and repeated the assay. Behavioral analysis showed 3xTg-AD mice had significantly impaired long-term contextual and cued fear memory compared to non-Tg mice that was further impaired by HFD. HFD significantly increased inflammatory markers and complement expression while decreasing synaptic marker expression only in 3xTg-AD mice, without altering AD pathology markers. Synaptoneurosomes from HFD-fed 3xTg-AD mice were phagocytosed at a significantly higher rate than those from chow-fed mice, suggesting the synapses were altered by HFD. The complement receptor inhibitor blocked this effect in a dose-dependent manner, demonstrating the HFD-mediated increase in phagocytosis was complement dependent. This study indicates HFD consumption increases neuroinflammation and over-activates the complement cascade in 3xTg-AD mice, resulting in poorer memory. The in vitro data point to complement as a potential mechanistic culprit and therapeutic target underlying HFD's influence in increasing cognitive vulnerability to AD.

The role of IL-1 family of cytokines in the pathogenesis and therapy of Alzheimer's disease

Alzheimer's disease (AD) is a progressive and irreversible neurological condition that occurs with age and poses a significant global public health concern, is distinguished by the degeneration of neurons and synapses in various regions of the brain. While the exact processes behind the neurodegeneration in AD are not completely known, it is now acknowledged that inflammation may have a significant impact on the beginning and advancement of AD neurodegeneration. The severity of many neurological illnesses can be influenced by the equilibrium between pro-inflammatory and anti-inflammatory mediators. The IL-1 family of cytokines is linked to innate immune responses, which are present in both acute inflammation and chronic inflammatory diseases. Research on the role of the IL-1 family in chronic neurological disease has been concentrated on AD. In this context, there is indirect evidence suggesting its involvement in the development of the disease. This review aims to provide a summary of the contribution of every IL-1 family member in AD pathogenesis, current immunotherapies in AD disease, and present treatment possibilities for either targeting or boosting these cytokines.

Crosstalk between bone and brain in Alzheimer's disease: Mechanisms, applications, and perspectives

Alzheimer's disease (AD) is a neurodegenerative disease that involves multiple systems in the body. Numerous recent studies have revealed bidirectional crosstalk between the brain and bone, but the interaction between bone and brain in AD remains unclear. In this review, we summarize human studies of the association between bone and brain and provide an overview of their interactions and the underlying mechanisms in AD. We review the effects of AD on bone from the aspects of AD pathogenic proteins, AD risk genes, neurohormones, neuropeptides, neurotransmitters, brain-derived extracellular vesicles (EVs), and the autonomic nervous system. Correspondingly, we elucidate the underlying mechanisms of the involvement of bone in the pathogenesis of AD, including bone-derived hormones, bone marrow-derived cells, bone-derived EVs, and inflammation. On the basis of the crosstalk between bone and the brain, we propose potential strategies for the management of AD with the hope of offering novel perspectives on its prevention and treatment. HIGHLIGHTS: The pathogenesis of AD, along with its consequent changes in the brain, may involve disturbing bone homeostasis. Degenerative bone disorders may influence the progression of AD through a series of pathophysiological mechanisms. Therefore, relevant bone intervention strategies may be beneficial for the comprehensive management of AD.

Systemic inflammation attenuates the repair of damaged brains through reduced phagocytic activity of monocytes infiltrating the brain

In this study, we examined how systemic inflammation affects repair of brain injury. To this end, we created a brain-injury model by stereotaxic injection of ATP, a damage-associated molecular pattern component, into the striatum of mice. Systemic inflammation was induced by intraperitoneal injection of lipopolysaccharide (LPS-ip). An analysis of magnetic resonance images showed that LPS-ip reduced the initial brain injury but slowed injury repair. An immunostaining analysis using the neuronal marker, NeuN, showed that LPS-ip delayed removal of dead/dying neurons, despite the fact that LPS-ip enhanced infiltration of monocytes, which serve to phagocytize dead cells/debris. Notably, infiltrating monocytes showed a widely scattered distribution. Bulk RNAseq analyses showed that LPS-ip decreased expression of genes associated with phagocytosis, with PCR and immunostaining of injured brains confirming reduced levels of Cd68 and Clec7a, markers of phagocytic activity, in monocytes. Collectively, these results suggest that systemic inflammation affects properties of blood monocytes as well as brain cells, resulting in delay in clearing damaged cells and activating repair processes.

Inflammation unites diverse acute and chronic diseases

BACKGROUND

Inflammation and immunity contribute pivotally to diverse acute and chronic diseases. Inflammatory pathways have become increasingly targets for therapy. Yet, despite substantial similarity in mechanisms and pathways, the scientific, medical, pharma and biotechnology sectors have generally focused programs finely on a single disease entity or organ system. This insularity may impede progress in innovation and the harnessing of powerful new insights into inflammation biology ripe for clinical translation.

METHODS

A multidisciplinary thinktank reviewed highlights how inflammation contributes to diverse diseases, disturbed homeostasis, ageing and impaired healthspan. We explored how common inflammatory and immune mechanisms that operate in key conditions in their respective domains. This consensus review highlights the high degree of commonality of inflammatory mechanisms in a diverse array of conditions that together contribute a major part of the global burden of morbidity and mortality and present an enormous challenge to public health and drain on resources.

RESULTS

We demonstrate how that shared inflammatory mechanisms unite many seemingly disparate diseases, both acute and chronic. The examples of infection, cardiovascular conditions, pulmonary diseases, rheumatological disorders, dementia, cancer and ageing illustrate the overlapping pathogenesis. We outline opportunities to synergize, reduce duplication and consolidate efforts of the clinical, research and pharmaceutical communities. Enhanced recognition of these commonalties should promote cross-fertilization and hasten progress in this rapidly moving domain.

CONCLUSIONS

Greater appreciation of the shared mechanisms should simplify understanding seemingly disparate diseases for clinicians and help them to recognize inflammation as a therapeutic target which the development of novel therapies is rendering actionable.

Immune-mediated disruption of the blood-brain barrier after intracerebral hemorrhage: Insights and potential therapeutic targets

AIMS

Intracerebral hemorrhage (ICH) is a condition that arises due to the rupture of cerebral blood vessels, leading to the flow of blood into the brain tissue. One of the pathological alterations that occurs during an acute ICH is an impairment of the blood-brain barrier (BBB), which leads to severe perihematomal edema and an immune response.

DISCUSSION

A complex interplay between the cells of the BBB, for example, pericytes, astrocytes, and brain endothelial cells, with resident and infiltrating immune cells, such as microglia, monocytes, neutrophils, T lymphocytes, and others accounts for both damaging and protective mechanisms at the BBB following ICH. However, the precise immunological influence of BBB disruption has yet to be richly ascertained, especially at various stages of ICH.

CONCLUSION

This review summarizes the changes in different cell types and molecular components of the BBB associated with immune-inflammatory responses during ICH. Furthermore, it highlights promising immunoregulatory therapies to protect the integrity of the BBB after ICH. By offering a comprehensive understanding of the mechanisms behind BBB damage linked to cellular and molecular immunoinflammatory responses after ICH, this article aimed to accelerate the identification of potential therapeutic targets and expedite further translational research.

Systemic immune challenge exacerbates neurodegeneration in a model of neurological lysosomal disease

Mucopolysaccharidosis type IIIA (MPS IIIA) is a rare paediatric lysosomal storage disorder, caused by the progressive accumulation of heparan sulphate, resulting in neurocognitive decline and behavioural abnormalities. Anecdotal reports from paediatricians indicate a more severe neurodegeneration in MPS IIIA patients, following infection, suggesting inflammation as a potential driver of neuropathology. To test this hypothesis, we performed acute studies in which WT and MPS IIIA mice were challenged with the TLR3-dependent viral mimetic poly(I:C). The challenge with an acute high poly(I:C) dose exacerbated systemic and brain cytokine expression, especially IL-1β in the hippocampus. This was accompanied by an increase in caspase-1 activity within the brain of MPS IIIA mice with concomitant loss of hippocampal GFAP and NeuN expression. Similar levels of cell damage, together with exacerbation of gliosis, were also observed in MPS IIIA mice following low chronic poly(I:C) dosing. While further investigation is warranted to fully understand the extent of IL-1β involvement in MPS IIIA exacerbated neurodegeneration, our data robustly reinforces our previous findings, indicating IL-1β as a pivotal catalyst for neuropathological processes in MPS IIIA.

Sex-dependent effects of carbohydrate source and quantity on caspase-1 activity in the mouse central nervous system

BACKGROUND

Mounting evidence links glucose intolerance and diabetes as aspects of metabolic dysregulation that are associated with an increased risk of developing dementia. Inflammation and inflammasome activation have emerged as a potential link between these disparate pathologies. As diet is a key factor in both the development of metabolic disorders and inflammation, we hypothesize that long term changes in dietary factors can influence nervous system function by regulating inflammasome activity and that this phenotype would be sex-dependent, as sex hormones are known to regulate metabolism and immune processes.

METHODS

5-week-old male and female transgenic mice expressing a caspase-1 bioluminescent reporter underwent cranial window surgeries and were fed control (65% complex carbohydrates, 15% fat), high glycemic index (65% carbohydrates from sucrose, 15% fat), or ketogenic (1% complex carbohydrates, 79% fat) diet from 6 to 26 weeks of age. Glucose regulation was assessed with a glucose tolerance test following a 4-h morning fast. Bioluminescence in the brain was quantified using IVIS in vivo imaging. Blood cytokine levels were measured using cytokine bead array. 16S ribosomal RNA gene amplicon sequencing of mouse feces was performed to assess alterations in the gut microbiome. Behavior associated with these dietary changes was also evaluated.

RESULTS

The ketogenic diet caused weight gain and glucose intolerance in both male and female mice. In male mice, the high glycemic diet led to increased caspase-1 biosensor activation over the course of the study, while in females the ketogenic diet drove an increase in biosensor activation compared to their respective controls. These changes correlated with an increase in inflammatory cytokines present in the serum of test mice and the emergence of anxiety-like behavior. The microbiome composition differed significantly between diets; however no significant link between diet, glucose tolerance, or caspase-1 signal was established.

CONCLUSIONS

Our findings suggest that diet composition, specifically the source and quantity of carbohydrates, has sex-specific effects on inflammasome activation in the central nervous system and behavior. This phenotype manifested as increased anxiety in male mice, and future studies are needed to determine if this phenotype is linked to alterations in microbiome composition.

Oxidative stress-mediated neuroinflammation in Alzheimer's disease

Reactive oxygen species (ROS) are metabolic by-products that constitute an indispensable component of physiological processes, albeit their heightened presence may proffer substantial perils to biological entities. Such a proliferation gives rise to a gradual escalation of oxidative stress within the organism, thereby compromising mitochondrial functionality and inflicting harm upon various bodily systems, with a particular predilection for the central nervous system. In its nascent stages, it is plausible that inflammation has been a facilitator in the progression of the malady. The precise role of inflammation in Alzheimer's disease (AD) remains somewhat enigmatic, although it is conceivable that activated microglia and astrocytes might be implicated in the removal of amyloid-β (Aβ) deposits. Nonetheless, prolonged microglial activation is associated with Tau phosphorylation and Aβ aggregation. Research studies have indicated that AD brains upregulate complementary molecules, inflammatory cytokines, acute phase reacting agents, and other inflammatory mediators that may cause neurodegeneration. In this review, oxidative damage products will be discussed as potential peripheral biomarkers for AD and its early stages. The disordered excretion of pro-inflammatory cytokines, chemokines, oxygen, and nitrogen-reactive species, along with the stimulation of the complement system by glial cells, has the potential to disrupt the functionality of neuronal termini. This perturbation, in turn, culminates in compromised synaptic function, a phenomenon empirically linked to the manifestation of cognitive impairments. The management of neurodegenerative conditions in the context of dementia necessitates therapeutic interventions that specifically target the excessive production of inflammatory and oxidative agents. Furthermore, we shall deliberate upon the function of microglia and oxidative injury in the etiology of AD and the ensuing neurodegenerative processes.

Correlation between abnormal cellular immune and changes of magnetic resonance spectroscopy in patients with Alzheimer's disease

BACKGROUND

Evidence from previous studies indicates that neuroinflammation contributes to the onset of Alzheimer's Disease (AD). Moreover, cellular dysfunction is induced by impaired signaling of neurotransmitters. This study aimed to explore the correlation between cellular immune dysfunction and neurotransmitter changes through cranial Magnetic Resonance Spectroscopy (MRS) in AD patients.

METHODS

Here, 32 AD, 40 Vascular Dementia (VD), and 35 Non-Dementia Elderly Control (NDE) cases were enrolled. Flow cytometry was performed to characterize lymphocyte subsets in plasma samples. The IL-1β and Caspase-1 levels were detected by ELISA. The NLRP3 expression level was measured by Western Blot (WB). The equivalence of N-acetylaspartate (NAA), Creatine (Cr), Choline (Cho), and Inositol (MI) in bilateral hippocampi of patients was examined by MRS. The association of NAA/Cr or MI/Cr ratios with the proportion of T lymphocyte subsets or NK cell subsets was determined through single-factor correlation analysis.

RESULTS

The proportion of T lymphocyte subsets was significantly lower in the AD group than in the NDE group (P < 0.01). On the other hand, the Caspase-1, NLRP3, and IL-1β protein expression levels were significantly higher in the AD group than in the other groups. Further analysis showed that the NAA/Cr ratio was lower in the AD group than in the NDE group. Additionally, a significant positive correlation was found between the NAA/Cr ratio and the MMSE score (r = 0.81, P < 0.01). Moreover, a significant positive correlation was observed between the NAA/Cr and T lymphocyte ratios. The NAA/Cr ratio was significantly negatively correlated with the proportion of NK cells in the blood (r = －0.83, P < 0.01). A significant negative correlation was also recorded between the MI/Cr and T cell ratios in blood samples.

CONCLUSIONS

Impaired cellular immune dysfunction in AD patients was significantly correlated with abnormal MRS. Neuroimmune dysfunction may contribute to the pathogenesis of AD and alter the metabolism of neurotransmitters such as aspartic acid and MI in the brains of AD patients.

TRIAL REGISTRATION

Not applicable.

Emergence of the brain-border immune niches and their contribution to the development of neurodegenerative diseases

Historically, the central nervous system (CNS) was regarded as 'immune-privileged', possessing its own distinct immune cell population. This immune privilege was thought to be established by a tight blood-brain barrier (BBB) and blood-cerebrospinal-fluid barrier (BCSFB), which prevented the crossing of peripheral immune cells and their secreted factors into the CNS parenchyma. However, recent studies have revealed the presence of peripheral immune cells in proximity to various brain-border niches such as the choroid plexus, cranial bone marrow (CBM), meninges, and perivascular spaces. Furthermore, emerging evidence suggests that peripheral immune cells may be able to infiltrate the brain through these sites and play significant roles in driving neuronal cell death and pathology progression in neurodegenerative disease. Thus, in this review, we explore how the brain-border immune niches may contribute to the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). We then discuss several emerging options for harnessing the neuroimmune potential of these niches to improve the prognosis and treatment of these debilitative disorders using novel insights from recent studies.

Roles of Cytokines in Alzheimer's Disease

The neuroimmune system is a collection of immune cells, cytokines, and the glymphatic system that plays a pivotal role in the pathogenesis and progression of Alzheimer's disease (AD). Of particular focus are cytokines, a group of immune signaling molecules that facilitate communication among immune cells and contribute to inflammation in AD. Extensive research has shown that the dysregulated secretion of certain cytokines (IL-1β, IL-17, IL-12, IL-23, IL-6, and TNF-α) promotes neuroinflammation and exacerbates neuronal damage in AD. However, anti-inflammatory cytokines (IL-2, IL-3, IL-33, and IL-35) are also secreted during AD onset and progression, thereby preventing neuroinflammation. This review summarizes the involvement of pro- and anti-inflammatory cytokines in AD pathology and discusses their therapeutic potential.

Experimental colitis in young Tg2576 mice accelerates the onset of an Alzheimer's-like clinical phenotype

Systemic inflammation and neuroinflammation affect the natural course of the sporadic form of Alzheimer's disease (AD), as supported by epidemiological and preclinical data, and several epidemiological studies indicate a higher prevalence of AD in patients with inflammatory bowel disease. In this study, we explored whether colitis induced by dextran sulfate sodium (DSS) in young, presymptomatic/preplaque mice worsens and/or anticipates age-dependent cognitive impairment in Tg2576, a widely used mouse model of AD. We demonstrated that DSS colitis induced in young Tg2576 mice anticipates the onset age of learning and memory deficit in the Morris water maze test. To explore potential mechanisms behind the acceleration of cognitive decline in Tg2576 mice by DSS colitis, we focused on gut microbiota, systemic inflammation and neuroinflammation markers. We observed a Firmicutes/Bacteroidetes ratio change in Tg2576 DSS animals comparable to that of elderly Tg2576 mice, suggesting accelerated microbiota aging in Tg2576 DSS mice, a change not observed in C57BL6 DSS mice. We also observed substantial differences between Tg2576 and WT mice in several inflammation and neuroinflammation-related parameters as early as 3 months of age, well before plaque deposition, a picture which evolved rapidly (between 3 and 5.5 months of age) in contrast to Tg2576 and WT littermates not treated with DSS. In detail, following induction of DSS colitis, WT and Tg2576 mice exhibited contrasting features in the expression level of inflammation-evoked astrocyte-associated genes in the hippocampus. No changes in microglial features occurred in the hippocampus between the experimental groups, whereas a reduced glial fibrillary acidic protein immunoreactivity was observed in Tg2576 vs. WT mice. This finding may reflect an atrophic, "loss-of-function" profile, further exacerbated by DSS where a decreased of GFAP mRNA expression level was detected. In conclusion, we suggest that as-yet unidentified peripheral mediators evoked by DSS colitis and involving the gut-brain axis emphasize an astrocyte "loss-of-function" profile present in young Tg2576 mice, leading to impaired synaptic morphological and functional integrity as a very early sign of AD.

Effect of total flavonoids of Dracocephalum moldavica L. On neuroinflammation in Alzheimer's disease model amyloid-β (Aβ1-42)-peptide-induced astrocyte activation

One of the main pathological features noted in Alzheimer's disease (AD) is the presence of plagues of aggregated β-amyloid (Aβ1-42)-peptides. Excess deposition of amyloid-β oligomers (AβO) are known to promote neuroinflammation. Sequentially, following neuroinflammation astrocytes become activated with cellular characteristics to initiate activated astrocytes. The purpose of this study was to determine whether total flavonoids derived from Dracocephalum moldavica L. (TFDM) inhibited Aβ1-42-induced damage attributed to activated C8-D1A astrocytes. Western blotting and ELISA were used to determine the expression of glial fibrillary acidic protein (GFAP), and complement C3 to establish the activation status of astrocytes following induction from exposure to Aβ1-42. Data demonstrated that stimulation of C8-D1A astrocytes by treatment with 40 μM Aβ1-42 for 24 hr produced significant elevation in protein expression and protein levels of acidic protein (GFAP) and complement C3 accompanied by increased expression and levels of inflammatory cytokines. Treatment with TFDM or the clinically employed drug donepezil in AD therapy reduced production of inflammatory cytokines, and toxicity initiated following activation of C8-D1A astrocytes following exposure to Aβ1-42. Therefore, TFDM similar to donepezil inhibited inflammatory secretion in reactive astrocytes, suggesting that TFDM may be considered as a potential compound to be utilized in AD therapy.

Mesenchymal Stem Cells-based Cell-free Therapy Targeting Neuroinflammation

Emerging from several decades of extensive research, key genetic elements and biochemical mechanisms implicated in neuroinflammation have been delineated, contributing substantially to our understanding of neurodegenerative diseases (NDDs). In this minireview, we discuss data predominantly from the past three years, highlighting the pivotal roles and mechanisms of the two principal cell types implicated in neuroinflammation. The review also underscores the extended process of peripheral inflammation that predates symptomatic onset, the critical influence of neuroinflammation, and their dynamic interplay in the pathogenesis of NDDs. Confronting these complex challenges, we introduce compelling evidence supporting the use of mesenchymal stem cell-based cell-free therapy. This therapeutic strategy includes the regulation of microglia and astrocytes, modulation of peripheral nerve cell inflammation, and targeted anti-inflammatory interventions specifically designed for NDDs, while also discussing engineering and safety considerations. This innovative therapeutic approach intricately modulates the immune system across the peripheral and nervous systems, with an emphasis on achieving superior penetration and targeted delivery. The insights offered by this review have significant implications for the better understanding and management of neuroinflammation.

TNF-α/TNFR1 activated astrocytes exacerbate depression-like behavior in CUMS mice

Neuroinflammation is considered to be a significant mechanism contributing to depression. Several studies have reported that A1 astrocytes were highly prevalent in human neuroinflammatory and neurodegenerative diseases. However, the precise mechanism by which A1 astrocytes contribute to depression remains unclear. Clinical studies have suggested a correlation between TNF-α, an activator of A1 astrocytes, and the severity of depression. Based on these findings, we hypothesized that TNF-α might worsen depression by activating A1 astrocytes. Our previous studies indicated that Rhodomyrtone (Rho) has the potential to improve depression-like behavior in mice. However, the exact mechanism for this effect has not been fully elucidated. Importantly, it was reported that Rho alleviated skin inflammation in a mouse model of psoriasis by inhibiting the expression of TNF-α. Based on this finding, we hypothesized that rhodomyrtone may exert antidepressant effects by modulating the TNF-α pathway. However, further research is required to investigate and validate these hypotheses, shedding light on the relationships between neuroinflammation, A1 astrocytes, TNF-α, and depression. By obtaining a deeper understanding of the underlying mechanisms, these findings could lead to the development of novel antidepressant strategies that target the TNF-α pathway in the context of neuroinflammation. In vivo, based on the established chronic unpredictable mild stress (CUMS) mouse depression model, we characterized the mechanism of TNF-α and Rho during depression by using several behavioral assays, adeno-associated virus(AAV) transfection, western blotting, immunofluorescence, and other experimental methods. In vitro, we characterized the effect of Rho on inflammation in TNF-α-treated primary astrocytes. TNFR1 expression was significantly increased in the hippocampus of depression-like mice, with increased astrocytes activation and neuronal apoptosis. These processes were further enhanced with increasing levels of TNF-α in the cerebrospinal fluid of mice. However, this process was attenuated by knockdown of TNFR1 and infliximab (Inf; a TNF-α antagonist). Injection of rhodomyrtone decreased the expressions of TNFR1 and TNF-α, resulting in significant improvements in mouse depression-like behaviors and reduction of astrocyte activation. TNF-α could be involved in the pathophysiological process of depression, through mediating astrocytes activation by binding to TNFR1. By blocking this pathway, Rho may be a novel antidepressant.

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

Tooth loss impairs cognitive function in SAMP8 mice via the NLRP3/Caspase-1 pathway

OBJECTIVE

Loss of occlusal support due to tooth loss has been indicated as one of the risk factors for Alzheimer's disease. This study aimed to investigate the relationship between tooth loss and cognitive dysfunction and illustrate the role of neuroinflammation in advancing Alzheimer's disease.

MATERIALS AND METHODS

Male 5-month-old senescence-accelerated mouse strain P8 (SAMP8) mice were divided into three groups (n = 7): the C (control), S (sham-operated), and TL (tooth loss) groups. The Morris water maze (MWM) test was performed to assess spatial memory. Additionally, histopathological and molecular assessments of hippocampal tissues were performed.

RESULTS

The TL groups exhibited impaired spatial memory in the water maze. Tooth loss induced higher protein expression levels of the neuroinflammation cytokine interleukin-1β (IL-1β) in the hippocampus than in the S and C groups. Tooth loss activated the NLRP3 inflammasome and increased the expression of Caspase-1 in the hippocampus.

CONCLUSIONS

The findings indicated that tooth loss impairs cognitive function in SAMP8 mice and is closely related to the activation of NLRP3/Caspase-1 in the hippocampus.

The shift in the fatty acid composition of the circulating lipidome in Alzheimer's disease

INTRODUCTION

Fatty acids (FAs) are the building blocks of complex lipids and signaling compounds; the role of the lipidome fatty acid profile (LFA) in AD progression remains unclear.

METHODS

The LFA of plasma and cerebrospinal fluid (CSF) samples from 289 participants (103 AD patients, 92 MCI patients, and 94 controls) was determined by GC-FID. The MCI subjects were followed up for 58 ± 12.5 months.

RESULTS

In controls, CSF has a more neuroprotective LFA than plasma. In CSF, a higher content of docosahexaenoic acid was associated with a reduced risk of MCI-to-AD progression. In plasma, higher oleic acid content was associated with lower risk of AD, MCI, and MCI-to-AD progression, whereas higher levels of vaccenic acid and docosahexaenoic acid were associated with greater risk of AD and MCI, and higher rate of MCI-to-AD progression, respectively.

DISCUSSION

The circulating LFA is involved in the pathogenesis and progression of AD.

HIGHLIGHTS

The lipidome fatty acid profile in CSF and plasma was markedly different. Higher levels of vaccenic acid and lower levels of oleic acid in plasma were associated with greater risk of Alzheimer's disease. In plasma, higher levels of oleic acid were associated with a reduced risk of MCI-to-AD progression. Higher levels of docosahexaenoic acid in CSF were associated with a lower risk of MCI-to-AD progression. Higher levels of docosahexaenoic acid in plasma were associated with a greater rate of MCI-to-AD progression.

Changes in SOD and NF-κB Levels in Substantia Nigra and the Intestine through Oxidative Stress Effects in a Wistar Rat Model of Ozone Pollution

This work aimed to elucidate how O3 pollution causes a loss of regulation in the immune response in both the brain and the intestine. In this work, we studied the effect of exposing rats to low doses of O3 based on the association between the antioxidant response of superoxide dismutase (SOD) levels and the nuclear factor kappa light chains of activated B cells (NFκB) as markers of inflammation. Method: Seventy-two Wistar rats were used, divided into six groups that received the following treatments: Control and 7, 15, 30, 60, and 90 days of O3. After treatment, tissues were extracted and processed using Western blotting, biochemical, and immunohistochemical techniques. The results indicated an increase in 4-hydroxynonenal (4HNE) and Cu/Zn-SOD and a decrease in Mn-SOD, and SOD activity in the substantia nigra, jejunum, and colon decreased. Furthermore, the translocation of NFκB to the nucleus increased in the different organs studied. In conclusion, repeated exposure to O3 alters the regulation of the antioxidant and inflammatory response in the substantia nigra and the intestine. This indicates that these factors are critical in the loss of regulation in the inflammatory response; they respond to ozone pollution, which can occur in chronic degenerative diseases.

Astrocytes at the intersection of ageing, obesity, and neurodegeneration

Once considered passive cells of the central nervous system (CNS), glia are now known to actively maintain the CNS parenchyma; in recent years, the evidence for glial functions in CNS physiology and pathophysiology has only grown. Astrocytes, a heterogeneous group of glial cells, play key roles in regulating the metabolic and inflammatory landscape of the CNS and have emerged as potential therapeutic targets for a variety of disorders. This review will outline astrocyte functions in the CNS in healthy ageing, obesity, and neurodegeneration, with a focus on the inflammatory responses and mitochondrial function, and will address therapeutic outlooks.

Effect of Regulation of Chemerin/Chemokine-like Receptor 1/Stimulator of Interferon Genes Pathway on Astrocyte Recruitment to Aβ Plaques

Recruitment and accumulation of reactive astrocytes around senile plaques are common pathological features of Alzheimer's disease (AD), with unclear mechanisms. Chemerin, an adipokine implicated in neuroinflammation, acts through its receptor, chemokine-like receptor 1 (CMKLR1), which also functions as a receptor for amyloid β (Aβ). The impact of the chemerin/CMKLR1 axis on astrocyte migration towards Aβ plaques is unknown. Here we investigated the effect of CMKLR1 on astrocyte migration around Aβ deposition in APP/PS1 mice with Cmklr1 knockout (APP/PS1-Cmklr1-/-). CMKLR1-expressed astrocytes were upregulated in the cortices and hippocampi of 9-month-old APP/PS1 mice. Chemerin mainly co-localized with neurons, and its expression was reduced in the brains of APP/PS1 mice, compared to WT mice. CMKLR1 deficiency decreased astrocyte colocalization with Aβ plaques in APP/PS1-Cmklr1-/- mice, compared to APP/PS1 mice. Activation of the chemerin/CMKLR1 axis promoted the migration of primary cultured astrocytes and U251 cells, and reduced astrocyte clustering induced by Aβ42. Mechanistic studies revealed that chemerin/CMKLR1 activation induced STING phosphorylation. Deletion of STING attenuated the promotion of the chemerin/CMKLR1 axis relative to astrocyte migration and abolished the inhibitory effect of chemerin on Aβ42-induced astrocyte clustering. These findings suggest the involvement of the chemerin/CMKLR1/STING pathway in the regulation of astrocyte migration and recruitment to Aβ plaques/Aβ42.

Cognitive Deficits and Alzheimer's Disease-Like Pathologies in the Aged Chinese Tree Shrew

Alzheimer's disease (AD) is the most common chronic progressive neurodegenerative disease in the elderly. It has an increasing prevalence and a growing health burden. One of the limitations in studying AD is the lack of animal models that show features of Alzheimer's pathogenesis. The tree shrew has a much closer genetic affinity to primates than to rodents and has great potential to be used for research into aging and AD. In this study, we aimed to investigate whether tree shrews naturally develop cognitive impairment and major AD-like pathologies with increasing age. Pole-board and novel object recognition tests were used to assess the cognitive performance of adult (about 1 year old) and aged (6 years old or older) tree shrews. The main AD-like pathologies were assessed by Western blotting, immunohistochemical staining, immunofluorescence staining, and Nissl staining. Our results showed that the aged tree shrews developed an impaired cognitive performance compared to the adult tree shrews. Moreover, the aged tree shrews exhibited several age-related phenotypes that are associated with AD, including increased levels of amyloid-β (Aβ) accumulation and phosphorylated tau protein, synaptic and neuronal loss, and reactive gliosis in the cortex and the hippocampal tissues. Our study provides further evidence that the tree shrew is a promising model for the study of aging and AD.

The Role of IL-6 in Neurodegenerative Disorders

"Neurodegenerative disorder" is an umbrella term for a group of fatal progressive neurological illnesses characterized by neuronal loss and inflammation. Interleukin-6 (IL-6), a pleiotropic cytokine, significantly affects the activities of nerve cells and plays a pivotal role in neuroinflammation. Furthermore, as high levels of IL-6 have been frequently observed in association with several neurodegenerative disorders, it may potentially be used as a biomarker for the progression and prognosis of these diseases. This review summarizes the production and function of IL-6 as well as its downstream signaling pathways. Moreover, we make a comprehensive review on the roles of IL-6 in neurodegenerative disorders and its potential clinical application.

Hypoxia inducible factor-1α regulates microglial innate immune memory and the pathology of Parkinson's disease

Neuroinflammation is one of the core pathological features of Parkinson's disease (PD). Innate immune cells play a crucial role in the progression of PD. Microglia, the major innate immune cells in the brain, exhibit innate immune memory effects and are recognized as key regulators of neuroinflammatory responses. Persistent modifications of microglia provoked by the first stimuli are pivotal for innate immune memory, resulting in an enhanced or suppressed immune response to second stimuli, which is known as innate immune training and innate immune tolerance, respectively. In this study, LPS was used to establish in vitro and in vivo models of innate immune memory. Microglia-specific Hif-1α knockout mice were further employed to elucidate the regulatory role of HIF-1α in innate immune memory and MPTP-induced PD pathology. Our results showed that different paradigms of LPS could induce innate immune training or tolerance in the nigrostriatal pathway of mice. We found that innate immune tolerance lasting for one month protected the dopaminergic system in PD mice, whereas the effect of innate immune training was limited. Deficiency of HIF-1α in microglia impeded the formation of innate immune memory and exerted protective effects in MPTP-intoxicated mice by suppressing neuroinflammation. Therefore, HIF-1α is essential for microglial innate immune memory and can promote neuroinflammation associated with PD.

Engineered Macrophage Membrane-Coated Nanoparticles with Enhanced CCR2 Expression Promote Spinal Cord Injury Repair by Suppressing Neuroinflammation and Neuronal death

Spinal cord injury (SCI) is a severe neurological disorder characterized by significant disability and limited treatment options. Mitigating the secondary inflammatory response following the initial injury is the primary focus of current research in the treatment of SCI. CCL2 (C─C motif chemokine ligand 2) serves as the primary regulator responsible for inflammatory chemotaxis of the majority of peripheral immune cells, blocking the CCL2-CCR2 (C─C chemokine receptor type 2) axis has shown considerable therapeutic potential for inflammatory diseases, including SCI. In this study, it presents a multifunctional biomimetic nanoplatform (CCR2-MM@PLGA/Cur) specifically designed to target the CCL2-CCR2 axis, which consisted of an engineered macrophage membrane (MM) coating with enhanced CCR2 expression and a PLGA (poly (lactic-co-glycolic acid)) nanoparticle that encapsulated therapeutic drugs. CCR2 overexpression on MM not only enhanced drug-targeted delivery to the injury site, but also attenuated macrophage infiltration, microglia pro-inflammatory polarization, and neuronal apoptosis by trapping CCL2. Consequently, it facilitated neural regeneration and motor function recovery in SCI mice, enabling a comprehensive treatment approach for SCI. The feasibility and efficacy of this platform are confirmed through a series of in vitro and in vivo assays, offering new insights and potential avenues for further exploration in the treatment of SCI.

Exosomes secreted from induced pluripotent stem cell ameliorate the lipopolysaccharide induced neuroinflammatory response via lncRNA-0949

PURPOSE

To study the effect of exosomes derived from the induced pluripotent stem cells (iPSCs) in the neuroinflammatory response of microglia caused by lipopolysaccharide (LPS) and reveal the potential underlying mechanism.

METHODS

A permanent microglia cell line HMO6 was activated by LPS. The features of exosomes were analyzed by nano flow cytometry, Western blot and transmission electron microscope. The RNA-seq was used to analyze the difference of noncoding RNA profiles between iPSC-Exos and HMO6 derived exosomes and proved that long no-coding RNA (lncRNA-0949) was highly expressed in the iPSC-Exos. Activated HMO6 cells were cocultured with iPSC-Exos in which lncRNA-0949 was overexpressed, knocked down or normally expressed. Quantitative real-time polymerase chain reaction (RT-qPCR), Enzyme-Linked Immunosorbent Assay and Western blot assay were adopted to analyze RNA and protein expression of inflammatory factors in HMO6 cells.

RESULTS

The oxidative stress and inflammatory response of microglia were significantly attenuated with the iPSC derived exosomes treatment. LncRNA-0949 was effectively delivered into the HMO6 cells through the iPSC-Exos, which largely alleviated the production of malondialdehyde, IL-6, IL-1β and TNF-α in HMO6 cells. Overexpression of lncRNA-0949 could enhance the anti-inflammatory effect of the iPSC-Exos, and knock-down of lncRNA-0949 impaired this availability.

CONCLUSION

According to our results, lncRNA-0949 enriched exosomes from iPSC could potentially be used as a therapeutic strategy to prevent/treat neuroinflammatory diseases.

Update of the European Society of Anaesthesiology and Intensive Care Medicine evidence-based and consensus-based guideline on postoperative delirium in adult patients

Postoperative delirium (POD) remains a common, dangerous and resource-consuming adverse event but is often preventable. The whole peri-operative team can play a key role in its management. This update to the 2017 ESAIC Guideline on the prevention of POD is evidence-based and consensus-based and considers the literature between 01 April 2015, and 28 February 2022. The search terms of the broad literature search were identical to those used in the first version of the guideline published in 2017. POD was defined in accordance with the DSM-5 criteria. POD had to be measured with a validated POD screening tool, at least once per day for at least 3 days starting in the recovery room or postanaesthesia care unit on the day of surgery or, at latest, on postoperative day 1. Recent literature confirmed the pathogenic role of surgery-induced inflammation, and this concept reinforces the positive role of multicomponent strategies aimed to reduce the surgical stress response. Although some putative precipitating risk factors are not modifiable (length of surgery, surgical site), others (such as depth of anaesthesia, appropriate analgesia and haemodynamic stability) are under the control of the anaesthesiologists. Multicomponent preoperative, intra-operative and postoperative preventive measures showed potential to reduce the incidence and duration of POD, confirming the pivotal role of a comprehensive and team-based approach to improve patients' clinical and functional status.

Emerging functions and therapeutic targets of IL-38 in central nervous system diseases

Interleukin (IL)-38 is a newly discovered cytokine of the IL-1 family, which binds various receptors (i.e., IL-36R, IL-1 receptor accessory protein-like 1, and IL-1R1) in the central nervous system (CNS). The hallmark physiological function of IL-38 is competitive binding to IL-36R, as does the IL-36R antagonist. Emerging research has shown that IL-38 is abnormally expressed in the serum and brain tissue of patients with ischemic stroke (IS) and autism spectrum disorder (ASD), suggesting that IL-38 may play an important role in neurological diseases. Important advances include that IL-38 alleviates neuromyelitis optica disorder (NMOD) by inhibiting Th17 expression, improves IS by protecting against atherosclerosis via regulating immune cells and inflammation, and reduces IL-1β and CXCL8 release through inhibiting human microglial activity post-ASD. In contrast, IL-38 mRNA is markedly increased and is mainly expressed in phagocytes in spinal cord injury (SCI). IL-38 ablation attenuated SCI by reducing immune cell infiltration. However, the effect and underlying mechanism of IL-38 in CNS diseases remain inadequately characterized. In this review, we summarize the biological characteristics, pathophysiological role, and potential mechanisms of IL-38 in CNS diseases (e.g., NMOD, Alzheimer's disease, ASD, IS, TBI, and SCI), aiming to explore the therapeutic potential of IL-38 in the prevention and treatment of CNS diseases.

Structure characterisation of polysaccharides purified from Boletus aereus Bull. and its improvement on AD-like behaviours via reliving neuroinflammation in APP/PS1 mice

The water-soluble neutral polysaccharide BEP2, with a molecular weight of 26.65 kDa, was isolated from the aqueous extract obtained from the fruiting bodies of Boletus aereus Bull. BEP2 primarily comprises Gal, with specific site substitutions speculated at partial positions, such as the substitution of -OCH3 at position H-3 or the branch at position C-2 including α-L-Fucp-(1→, α-D-Manp-(1 → and α-D-Manp-(1 → 3)-α-L-Fucp-(1 → 6)-β-D-Glcp-(1→. Treatment with BEP2 significantly enhanced learning, memory, and cognitive function, while concurrently reducing the accumulation of β-amyloid and suppressing neuroinflammation within the brains of APP/PS1 mice. Based on the results of biochemical detection, gut microbiota analysis, and metabolomic profiling, we found that BEP2 significantly upregulated the abundance of two bacterial families while downregulation that of seven bacterial families within the intestinal ecosystem. Notably, the abundance of the S24-7 family was significantly increased. Treatment with BEP2 upregulated five metabolites, while downregulating three metabolites, including norepinephrine. Additionally, BEP2 decreased the levels of interleukin (IL)-1β and IL-6, regulated the activities of microglial cells and astrocytes and increased the levels of the chemokine fractalkine (CX3CL1) and its receptor on microglia (CX3CR1), as well as that of transforming growth factor (TGF)-β1. These findings confirmed the suppressive effects of BEP2 on neuroinflammation.

Increased cysteinyl-tRNA synthetase drives neuroinflammation in Alzheimer's disease

BACKGROUND

Microglia-mediated neuroinflammation in Alzheimer's disease (AD) is not only a response to pathophysiological events, but also plays a causative role in neurodegeneration. Cytoplasmic cysteinyl-tRNA synthetase (CARS) is considered to be a stimulant for immune responses to diseases; however, it remains unknown whether CARS is involved in the pathogenesis of AD.

METHODS

Postmortem human temporal cortical tissues at different Braak stages and AD patient-derived serum samples were used to investigate the changes of CARS levels in AD by immunocytochemical staining, real-time PCR, western blotting and ELISA. After that, C57BL/6J and APP/PS1 transgenic mice and BV-2 cell line were used to explore the role of CARS protein in memory and neuroinflammation, as well as the underlying mechanisms. Finally, the associations of morphological features among CARS protein, microglia and dense-core plaques were examined by immunocytochemical staining.

RESULTS

A positive correlation was found between aging and the intensity of CARS immunoreactivity in the temporal cortex. Both protein and mRNA levels of CARS were increased in the temporal cortex of AD patients. Immunocytochemical staining revealed increased CARS immunoreactivity in neurons of the temporal cortex in AD patients. Moreover, overexpression of CARS in hippocampal neurons induced and aggravated cognitive dysfunction in C57BL/6J and APP/PS1 mice, respectively, accompanied by activation of microglia and the TLR2/MyD88 signaling pathway as well as upregulation of proinflammatory cytokines. In vitro experiments showed that CARS treatment facilitated the production of proinflammatory cytokines and the activation of the TLR2/MyD88 signaling pathway of BV-2 cells. The accumulation of CARS protein occurred within dense-core Aβ plaques accompanied by recruitment of ameboid microglia. Significant upregulation of TLR2/MyD88 proteins was also observed in the temporal cortex of AD.

CONCLUSIONS

The findings suggest that the neuronal CARS drives neuroinflammation and induces memory deficits, which might be involved in the pathogenesis of AD.

Exploring the Action Mechanism and Validation of the Key Pathways of Dendrobium officinale Throat-clearing Formula for the Treatment of Chronic Pharyngitis Based on Network Pharmacology

AIM

This study investigated the molecular action mechanism of a compound herb, also known as the Dendrobium officinale throat-clearing formula (QYF), by using network pharmacology and animal experimental validation methods to treat chronic pharyngitis (CP).

METHODS

The active ingredients and disease targets of QYF were determined by searching the Batman-TCM and GeneCards databases. Subsequently, the drug-active ingredient-target and protein-protein interaction networks were constructed, and the core targets were obtained through network topology. The Metascape database was screened, and the core targets were enriched with Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes.

RESULTS

In total, 1403 and 241 potential targets for drugs and diseases, respectively, and 81 intersecting targets were yielded. The core targets included TNF, IL-6, and IL-1β, and the core pathways included PI3K-Akt. The QYF treatment group exhibited effectively improved general signs, enhanced anti-inflammatory ability in vitro, reduced serum and tissue expressions of TNF- α, IL-6, and IL-1β inflammatory factors, and decreased blood LPS levels and Myd88, TLR4, PI3K, Akt, and NF-κB p65 protein expression in the tissues.

CONCLUSION

QYF could inhibit LPS production, which regulated the expression of the TLR4/PI3K/Akt/NF-κB signaling pathway to suppress the expression of the related inflammatory factors (i.e., TNF-α, IL-6, and IL-1β), thereby alleviating the CP process.

The Effects of Different Exercise Interventions on Patients with Subjective Cognitive Decline: A Systematic Review and Network Meta-Analysis

BACKGROUND AND OBJECTIVE

Exercise is a promising non-pharmacological therapy for subjective cognitive decline, but it is unclear which type of exercise is most effective. The objective was to assess the comparative effects and ranks of all exercise-based interventions on cognitive function in patients with subjective cognitive decline (SCD).

METHOD

In this network meta-analysis, Online databases for Web of Science, PubMed, Embase, Medline, Cochrane Library and PsycINFO were searched from inception to April 30, 2023. The included studies are randomized controlled trials assessing the efficacy of exercise interventions for individuals with SCD. The primary outcome measure is memory, while secondary outcome measures encompass executive function, attention, verbal fluency, and global cognitive function. Represented using Standardized Mean Differences (SMDs) along with their 95% Confidence Intervals (CIs). Bias assessment was conducted in accordance with the 'Cochrane Risk of Bias Assessment Tool, 2nd Edition' (RoB 2). Pairwise meta-analysis was carried out using the 'meta-analysis' module within STATA 14.0, and network meta-analysis was performed using the 'mvmeta' and 'network' packages available in STATA 14.0. Registration number CRD42023289687.

RESULT

This study included a total of 11 randomized controlled trials, encompassing 1,166 patients. Mind-body exercise was found to be efficacious in enhancing or sustaining memory (SMD: 0.58, 95%CI: 0.06 ~ 1.10) and executive function (SMD: 0.41, 95%CI: 0.09 ~ 0.73) in individuals with subjective cognitive decline. Furthermore, mind-body exercise exhibited the highest probability of being the most effective measures for improving or preventing the decline in memory (surface under cumulative ranking curve (SUCRA) value: 90.4) and executive function (SUCRA value: 91.8). The second-ranked moderate-intensity aerobic exercise has also shown a positive effect on the improvement of executive function in patients with subjective cognitive decline (SMD: 0.23, 95%CI: 0.03 ~ 0.43, SUCRA value: 68.2). However, we did not observe a significant effectiveness of exercise interventions on verbal fluency, attention, and overall cognitive function in subjective cognitive decline.

CONCLUSION

Mind-body exercise may potentially be the optimal strategies for enhancing memory and executive function in individuals with subjective cognitive decline. Additionally, moderate-intensity aerobic exercise has shown a modest positive effect on executive function in subjective cognitive decline. When resources permit, practical application of these findings may be considered. Nevertheless, further support for the conclusions of this study is warranted through larger sample sizes and well-designed multicenter trials.

Causal Association Between Sepsis and Neurodegenerative Diseases: A Bidirectional Two-Sample Mendelian Randomization Study

BACKGROUND

Previous observational studies suggested an association between sepsis and neurodegenerative diseases, but causality remains unclear.

OBJECTIVE

Determining the causal association between sepsis and four neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Lewy body dementia) through bidirectional two-sample Mendelian randomization (MR) analysis.

METHODS

Genome-wide association study summary statistics for all traits were obtained from publicly available databases. Inverse variance weighted (IVW) was the primary method for evaluating causal associations. In addition, three additional MR methods (MR-Egger, weighted median, and maximum likelihood method) were employed to supplement IVW. Furthermore, various sensitivity tests were conducted to assess the reliability: 1) Cochrane's Q test for assessing heterogeneity; 2) MR-Egger intercept test and MR-PRESSO global test for evaluating horizontal pleiotropy; 3) leave-one-out sensitivity test for determining the stability.

RESULTS

The results of IVW indicated that sepsis significantly increased the risk of Alzheimer's disease (OR = 1.11, 95% CI: 1.01-1.21, p = 0.025). In addition, three additional MR methods suggested parallel results. However, no causal effect of sepsis on the three other neurodegenerative diseases was identified. Subsequently, reverse MR analysis indicated that the four neurodegenerative diseases do not causally affect sepsis. Furthermore, sensitivity tests demonstrated the reliability of the MR analyses, suggesting no heterogeneity or horizontal pleiotropy.

CONCLUSIONS

The present study contributes to a deeper comprehension of the intricate interplay between sepsis and neurodegenerative disorders, thereby offering potential avenues for the development of therapeutic agents that can effectively mitigate the multifarious complications associated with sepsis.

Infectious Diseases

Microglia, brain-resident innate immune cells, have been extensively studied in neurodegenerative contexts like Alzheimer's disease. The Coronavirus disease 2019 (COVID-19) pandemic highlighted how peripheral infection and inflammation can be detrimental to the neuroimmune milieu and initiate microgliosis driven by peripheral inflammation. Microglia can remain deleterious to brain health by sustaining inflammation in the central nervous system even after the clearance of the original immunogenic agents. In this chapter, we discuss how pulmonary infection with Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) can lead to neurovascular and neuroimmune inflammation causing the neurological syndrome of post-acute sequelae of COVID-19 (PASC). Further, we incorporate lessons from the Human Immunodeficiency Virus' (HIV's) effects on microglial functioning in the era of combined antiretroviral therapies (cART) that contribute to HIV-1 associated neurocognitive disorders (HAND). Finally, we describe roles for mixed lineage kinase 3 (MLK3) and leucine-rich repeat kinase (LRRK2) as key regulators of multiple inflammatory and apoptotic pathways important to the pathogenesis of PASC and HAND. Inhibition of these pathways provides a therapeutically synergistic method of treating both PASC and HAND.

TLR4/Rac1/NLRP3 Pathway Mediates Amyloid-β-Induced Neuroinflammation in Alzheimer's Disease

Background

Neuroinflammation plays a crucial part in the initial onset and progression of Alzheimer's disease (AD). NLRP3 inflammasome was demonstrated to get involved in amyloid-β (Aβ)-induced neuroinflammation. However, the mechanism of Aβ-triggered activation of NLRP3 inflammasome remains poorly understood.

Objective

Based on our previous data, the study aimed to identify the downstream signals that bridge the activation of TLR4 and NLRP3 inflammasome associated with Aβ.

Methods

BV-2 cells were transfected with TLR4siRNA or pretreated with a CLI-095 or NSC23766, followed by Aβ1-42 treatment. APP/PS1 mice were injected intraperitoneally with CLI-095 or NSC23766. NLRP3 inflammasome and microglia activation was detected with immunostaining and western blot. G-LISA and Rac1 pull-down activation test were performed to investigate the activation of Rac1. Real-time PCR and ELISA were used to detect the inflammatory cytokines. Aβ plaques were assessed by western blotting and immunofluorescence staining. Morris water maze test was conducted to determine the spatial memory in mice.

Results

Rac1 and NLRP3 inflammasome were activated by Aβ in both in vitro and in vivo experiments. Inhibition of TLR4 reduced the activity of Rac1 and NLRP3 inflammasome induced by Aβ1-42. Furthermore, inhibition of Rac1 blocked NLRP3 inflammasome activation mediated by TLR4. Blocking the pathway by CLI095 or NSC23766 suppressed Aβ1-42-triggered activation of microglia, reduced the expression of pro-inflammatory mediators and ameliorated the cognition deficits in APP/PS1 mice.

Conclusions

Our study demonstrated that TLR4/Rac1/NLRP3 pathway mediated Aβ-induced neuroinflammation, which unveiled a novel pathway and key contributors underlying the pathogenic mechanism of Aβ.

Targeting CB2R in astrocytes for Parkinson's disease therapy: unraveling the Foxg1-mediated neuroprotective mechanism through autophagy-mediated NLRP3 degradation

BACKGROUND

Inflammasomes in astrocytes have been shown to play a crucial role in the pathogenesis of neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD). Cannabinoid Receptor 2(CB2R), a G protein-coupled receptor (GPCR), is considered a promising therapeutic target in inflammation-related disorders. This study aims to explore the role of CB2R in regulating NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated neuroinflammation in astrocytes.

METHODS

In an in vivo animal model, specific targeting of astrocytic CB2R was achieved by injecting CB2R-specific adenovirus (or fork head box g1(foxg1) adenovirus) to knock down CB2R or administering CB2R agonists, inhibitors, etc., in the substantia nigra pars compacta (SNc) of mice. A PD mouse model was established using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induction. Animal behavioral tests, western blot, immunofluorescence, and other experiments were performed to assess the loss of midbrain tyrosine hydroxylase (TH) neurons, activation of astrocytes, and activation of the NLRP3 pathway. Primary astrocytes were cultured in vitro, and NLRP3 inflammasomes were activated using 1-methyl-4-phenylpyridinium (MPP+) or lipopolysaccharide (LPS) and adenosine triphosphate (ATP). Western blot and ELISA experiments were conducted to assess the release of inflammatory factors. Transcriptomic sequencing and CUT&RUN techniques were employed to study the CB2R regulation of the foxg1 binding site on the autophagy molecule microtubule-associated protein 1 light chain 3 beta (MAP1LC3B).

RESULTS

Astrocytic CB2R knockdown impaired the motor abilities of MPTP-induced mice, exacerbated the loss of TH neurons, and induced activation of the NLRP3/Caspase-1/interleukin 1 (IL-1β) pathway. Activation of CB2R significantly alleviated motor impairments in mice while reducing NLRP3 deposition on astrocytes. In vitro cell experiments showed that CB2R activation attenuated the activation of the NLRP3/Caspase-1/IL-1β pathway induced by LPS + ATP or MPP+. Additionally, it inhibited the binding of foxg1 to MAP1LC3B, increased astrocytic autophagy levels, and facilitated NLRP3 degradation through the autophagy-lysosome pathway.

CONCLUSION

Activation of CB2R on astrocytes effectively mitigates NLRP3-mediated neuroinflammation and ameliorates the disease characteristics of PD in mice. CB2R represents a potential therapeutic target for treating PD.

Bridging the Gap: Investigating the Link between Inflammasomes and Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is a cluster of cognitive problems that may arise after surgery. POCD symptoms include memory loss, focus inattention, and communication difficulties. Inflammasomes, intracellular multiprotein complexes that control inflammation, may have a significant role in the development of POCD. It has been postulated that the NLRP3 inflammasome promotes cognitive impairment by triggering the inflammatory response in the brain. Nevertheless, there are many gaps in the current literature to understand the underlying pathophysiological mechanisms and develop future therapy. This review article underlines the limits of our current knowledge about the NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome and POCD. We first discuss inflammasomes and their types, structures, and functions, then summarize recent evidence of the NLRP3 inflammasome's involvement in POCD. Next, we propose a hypothesis that suggests the involvement of inflammasomes in multiple organs, including local surgical sites, blood circulation, and other peripheral organs, leading to systemic inflammation and subsequent neuronal dysfunction in the brain, resulting in POCD. Research directions are then discussed, including analyses of inflammasomes in more clinical POCD animal models and clinical trials, studies of inflammasome types that are involved in POCD, and investigations into whether inflammasomes occur at the surgical site, in circulating blood, and in peripheral organs. Finally, we discuss the potential benefits of using new technologies and approaches to study inflammasomes in POCD. A thorough investigation of inflammasomes in POCD might substantially affect clinical practice.

Ginsenoside Rg2 alleviates neurovascular damage in 3xTg-AD mice with Alzheimer's disease through the MAPK-ERK pathway

Alzheimer's disease (AD) is the most common form of dementia, and ginsenoside Rg2 (Rg2) is proven to inhibit AD's progression. This study investigates the potential benefits of Rg2 treatment on 3xTg-AD mice. Following 6 weeks of gavage treatment, Rg2-treated 3xTg-AD mice exhibited improved spatial recognition memory behaviors, regional cerebral blood flow, and histopathological injury of the hippocampus, which were observed through a Y-maze test, laser Doppler flowmetry, and hematoxylin-eosin staining. Additionally, Rg2 treatment caused a decrease in the levels of amyloid beta 25-35, TNF-α, IL-1β, and IL-6, as measured by enzyme-linked immunosorbent assay, as well as a reduction in mRNA levels of IL-1β and IL-6 in 3xTg-AD mouse brains using quantitative real-time PCR. In particular, NeuN and CD31 levels were inhibited and GFAP level was elevated in 3xTg-AD mice that were observed through immunofluorescence, and these levels were all antagonized by Rg2, suggesting the effects of Rg2 on neurovascular damage, astrocyte activation, and neuronal loss. Furthermore, Western blot and qRT-PCR assays showed that Rg2 blocked the expression of ICAM-1 and VCAM-1 in 3xTg-AD mice. By Western blot, the ratios of p-ERK/ERK and p-MAPK/MAPK in 3xTg-AD mice were upregulated by Rg2 treatment, suggesting the neuroprotective effects of Rg2 may be related to the MAPK-ERK pathway. In summary, this study demonstrated the potential of Rg2 to improve AD and provided a scientific basis for research on the biological mechanism of AD and the development of Rg2.

Clinical Phenotypes of Progressive Supranuclear Palsy-The Differences in Interleukin Patterns

Progressive supranuclear palsy (PSP) is an atypical parkinsonian syndrome based on tau pathology; its clinical phenotype differs, but PSP with Richardson's syndrome (PSP-RS) and the PSP parkinsonism predominant (PSP-P) variant remain the two most common manifestations. Neuroinflammation is involved in the course of the disease and may cause neurodegeneration. However, an up-to-date cytokine profile has not been assessed in different PSP phenotypes. This study aimed to evaluate possible differences in neuroinflammatory patterns between the two most common PSP phenotypes. Serum and cerebrospinal fluid (CSF) concentrations of interleukin-1 beta (IL-1β) and IL-6 were analyzed using enzyme-linked immunosorbent assay (ELISA) kits in 36 study participants-12 healthy controls and 24 patients with a clinical diagnosis of PSP-12 PSP-RS and 12 PSP-P. Disease duration among PSP patients ranged from three to six years. All participants underwent basic biochemical testing, and neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) values were calculated. Due to a lack of neuropathological examinations, as all patients remain alive, total tau levels were assessed in the CSF. Tau levels were significantly higher in the PSP-P and PSP-RS groups compared to the healthy controls. The lowest concentrations of serum and CSF interleukins were observed in PSP-RS patients, whereas PSP-P patients and healthy controls had significantly higher interleukin concentrations. Furthermore, there was a significant correlation between serum IL-6 levels and PLR in PSP-RS patients. The results indicate the existence of distinct neuroinflammatory patterns or a neuroprotective role of increased inflammatory activity, which could cause the differences between PSPS phenotypes and clinical course. The causality of the correlations described requires further studies to be confirmed.

Activation of multiple Eph receptors on neuronal membranes correlates with the onset of optic neuropathy

BACKGROUND

Optic neuropathy is a major cause of irreversible blindness, yet the molecular determinants that contribute to neuronal demise have not been fully elucidated. Several studies have identified 'ephrin signaling' as one of the most dysregulated pathways in the early pathophysiology of optic neuropathy with varied etiologies. Developmentally, gradients in ephrin signaling coordinate retinotopic mapping via repulsive modulation of cytoskeletal dynamics in neuronal membranes. Little is known about the role ephrin signaling plays in the post-natal visual system and its correlation with the onset of optic neuropathy.

METHODS

Postnatal mouse retinas were collected for mass spectrometry analysis for erythropoietin-producing human hepatocellular (Eph) receptors. Optic nerve crush (ONC) model was employed to induce optic neuropathy, and proteomic changes during the acute phase of neuropathic onset were analyzed. Confocal and super-resolution microscopy determined the cellular localization of activated Eph receptors after ONC injury. Eph receptor inhibitors assessed the neuroprotective effect of ephrin signaling modulation.

RESULTS

Mass spectrometry revealed expression of seven Eph receptors (EphA2, A4, A5, B1, B2, B3, and B6) in postnatal mouse retinal tissue. Immunoblotting analysis indicated a significant increase in phosphorylation of these Eph receptors 48 h after ONC. Confocal microscopy demonstrated the presence of both subclasses of Eph receptors within the retina. Stochastic optical reconstruction microscopy (STORM) super-resolution imaging combined with optimal transport colocalization analysis revealed a significant co-localization of activated Eph receptors with injured neuronal cells, compared to uninjured neuronal and/or injured glial cells, 48 h post-ONC. Eph receptor inhibitors displayed notable neuroprotective effects for retinal ganglion cells (RGCs) after six days of ONC injury.

CONCLUSIONS

Our findings demonstrate the functional presence of diverse Eph receptors in the postnatal mammalian retina, capable of modulating multiple biological processes. Pan-Eph receptor activation contributes to the onset of neuropathy in optic neuropathies, with preferential activation of Eph receptors on neuronal processes in the inner retina following optic nerve injury. Notably, Eph receptor activation precedes neuronal loss. We observed a neuroprotective effect on RGCs upon inhibiting Eph receptors. Our study highlights the importance of investigating this repulsive pathway in early optic neuropathies and provides a comprehensive characterization of the receptors present in the developed retina of mice, relevant to both homeostasis and disease processes.

Immune-related signature of periodontitis and Alzheimer's disease linkage

Background: Periodontits (PD) and Alzheimer's disease (AD) are both associated with ageing and clinical studies increasingly evidence their association. However, specific mechanisms underlying this association remain undeciphered, and immune-related processes are purported to play a signifcant role. The accrual of publicly available transcriptomic datasets permits secondary analysis and the application of data-mining and bioinformatic tools for biological discovery. Aim: The present study aimed to leverage publicly available transcriptomic datasets and databases, and apply a series of bioinformatic analysis to identify a robust signature of immune-related signature of PD and AD linkage. Methods: We downloaded gene-expresssion data pertaining PD and AD and identified crosstalk genes. We constructed a protein-protein network analysis, applied immune cell enrichment analysis, and predicted crosstalk immune-related genes and infiltrating immune cells. Next, we applied consisent cluster analysis and performed immune cell bias analysis, followed by LASSO regression to select biomarker immune-related genes. Results: The results showed a 3 gene set comprising of DUSP14, F13A1 and SELE as a robust immune-related signature. Macrophages M2 and NKT, B-cells, CD4+ memory T-cells and CD8+ naive T-cells emerged as key immune cells linking PD with AD. Conclusion: Candidate immune-related biomarker genes and immune cells central to the assocation of PD with AD were identified, and merit investigation in experimental and clinical research.

Tranexamic acid improves psoriasis-like skin inflammation: Evidence from in vivo and in vitro studies

The chronic disease psoriasis is associated with severe inflammation and abnormal keratinocyte propagation in the skin. Tranexamic acid (TXA), a plasmin inhibitor, is used to cure serious bleeding. We investigated whether TXA ointment mitigated Imiquimod (IMQ)-induced psoriasis-like inflammation. Furthermore, this study investigated the effect of noncytotoxic concentrations of TXA on IL-17-induced human keratinocyte (HaCaT) cells to determine the status of proliferative psoriatic keratinocytes. We found that TXA reduced IMQ-induced psoriasis-like erythema, thickness, scaling, and cumulative scores (erythema plus thickness plus scaling) on the back skin of BALB/c mice. Additionally, TXA decreased ear thickness and suppressed hyperkeratosis, hyperplasia, and inflammation of the ear epidermis in IMQ-induced BALB/c mice. Furthermore, TXA inhibited IMQ-induced splenomegaly in BALB/c mouse models. In IL-17-induced HaCaT cells, TXA inhibited ROS production and IL-8 secretion. Interestingly, TXA suppressed the IL-17-induced NFκB signaling pathway via IKK-mediated IκB degradation. TXA inhibited IL-17-induced activation of the NLRP3 inflammasome through caspase-1 and IL1β expression. TXA inhibited IL-17-induced NLRP3 inflammasome activation by enhancing autophagy, as indicated by LC3-II accumulation, p62/SQSTM1 expression, ATG4B inhibition, and Beclin-1/Bcl-2 dysregulation. Notably, TXA suppressed IL-17-induced Nrf2-mediated keratin 17 expression. N-acetylcysteine pretreatment reversed the effects of TXA on NFκB, NLRP3 inflammasomes, and the Nrf2-mediated keratin 17 pathway in IL-17-induced HaCaT cells. Results further confirmed that in the ear skin of IMQ-induced mice, psoriasis biomarkers such as NLRP3, IL1β, Nrf2, and keratin 17 expression were downregulated by TXA treatment. TXA improves IMQ-induced psoriasis-like inflammation in vivo and psoriatic keratinocytes in vitro. Tranexamic acid is a promising future treatment for psoriasis.

Pyroptosis: the potential eye of the storm in adult-onset Still's disease

Pyroptosis, a form of programmed cell death with a high pro-inflammatory effect, causes cell lysis and leads to the secretion of countless interleukin-1β (IL-1β) and IL-18 cytokines, resulting in a subsequent extreme inflammatory response through the caspase-1-dependent pathway or caspase-1-independent pathway. Adult-onset Still's disease (AOSD) is a systemic inflammatory disease with extensive disease manifestations and severe complications such as macrophage activation syndrome, which is characterized by high-grade inflammation and cytokine storms regulated by IL-1β and IL-18. To date, the pathogenesis of AOSD is unclear, and the available therapy is unsatisfactory. As such, AOSD is still a challenging disease. In addition, the high inflammatory states and the increased expression of multiple pyroptosis markers in AOSD indicate that pyroptosis plays an important role in the pathogenesis of AOSD. Accordingly, this review summarizes the molecular mechanisms of pyroptosis and describes the potential role of pyroptosis in AOSD, the therapeutic practicalities of pyroptosis target drugs in AOSD, and the therapeutic blueprint of other pyroptosis target drugs.

Concurrent Brain Subregion Microgliosis in an HLA-II Mouse Model of Group A Streptococcal Skin Infection

The broad range of clinical manifestations and life-threatening infections caused by the Gram-positive bacterium, Streptococcus pyogenes or Group A Streptococcus (GAS), remains a significant concern to public health, with a subset of individuals developing neurological complications. Here, we examined the concurrent neuroimmune effects of subcutaneous GAS infections in an HLA-Class II (HLA) transgenic mouse model of subcutaneous GAS infection. To investigate changes in the skin-brain axis, HLA-DQ8 (DQA1*0301/DQB1*0302) mice (DQ8) were randomly divided into three groups: uninfected controls (No Inf), GAS infected and untreated (No Tx), and GAS infected with a resolution by clindamycin (CLN) treatment (CLN Tx) (10 mg/kg/5 days) and were monitored for 16 days post-infection. While the skin GAS burden was significantly reduced by CLN, the cortical and hippocampal GAS burden in the male DQ8 mice was not significantly reduced with CLN. Immunoreactivity to anti-GAS antibody revealed the presence of GAS bacteria in the vicinity of the neuronal nucleus in the neocortex of both No Tx and CLN Tx male DQ8 mice. GAS infection-mediated cortical cytokine changes were modest; however, compared to No Inf or No Tx groups, a significant increase in IL-2, IL-13, IL-22, and IL-10 levels was observed in CLN Tx females despite the lack of GAS burden. Western blot analysis of cortical and hippocampal homogenates showed significantly higher ionized calcium-binding adaptor-1 (Iba-1, microglia marker) protein levels in No Tx females and males and CLN Tx males compared to the No Inf group. Immunohistochemical analysis showed that Iba-1 immunoreactivity in the hippocampal CA3 and CA1 subregions was significantly higher in the CLN Tx males compared to the No Tx group. Our data support the possibility that the subcutaneous GAS infection communicates to the brain and is characterized by intraneuronal GAS sequestration, brain cytokine changes, Iba-1 protein levels, and concurrent CA3 and CA1 subregion-specific microgliosis, even without bacteremia.

Molecular and environmental contributors to neurological complications in sickle cell disease

Sickle cell disease (SCD) is an inherited hemoglobinopathy in which affected hemoglobin polymerizes under hypoxic conditions resulting in red cell distortion and chronic hemolytic anemia. SCD affects millions of people worldwide, primarily in Sub-Saharan Africa and the Indian subcontinent. Due to vaso-occlusion of sickled red cells within the microvasculature, SCD affects virtually every organ system and causes significant morbidity and early mortality. The neurological complications of SCD are particularly devastating and diverse, ranging from overt stroke to covert cerebral injury, including silent cerebral infarctions and blood vessel tortuosity. However, even individuals without evidence of neuroanatomical changes in brain imaging have evidence of cognitive deficits compared to matched healthy controls likely due to chronic cerebral hypoxemia and neuroinflammation. In this review, we first examined the biological contributors to SCD-related neurological complications and then discussed the equally important socioenvironmental contributors. We then discuss the evidence for neuroprotection from the two primary disease-modifying therapies, chronic monthly blood transfusions and hydroxyurea, and end with several experimental therapies designed to specifically target these complications.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

A brain cytokine-independent switch in cortical activity marks the onset of sickness behavior triggered by acute peripheral inflammation

Systemic inflammation triggers protective as well as pro-inflammatory responses in the brain based on neuronal and/or cytokine signaling, and it associates with acutely and protractedly disrupted cognition. However, the multiple mechanisms underlying the peripheral-central inflammatory signaling are still not fully characterized. We used intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) in freely moving mice with chronically implanted electrodes for recording of local field potentials (LFP) and electrocorticography (ECoG) in the hippocampus and neocortex, respectively. We show here that a sudden switch in the mode of network activity occurred in both areas starting at 10-15 min after the LPS injection, simultaneously with a robust change from exploration to sickness behavior. This switch in cortical mode commenced before any elevations in pro-inflammatory cytokines IL-1β, TNFα, CCL2 or IL-6 were detected in brain tissue. Thereafter, this mode dominated cortical activity for the recording period of 3 h, except for a partial and transient recovery around 40 min post-LPS. These effects were closely paralleled by changes in ECoG spectral entropy. Continuous recordings for up to 72 h showed a protracted attenuation in hippocampal activity, while neocortical activity recovered after 48 h. The acute sickness behavior recovered by 72 h post-LPS. Notably, urethane (1.3 mg/kg) administered prior to LPS blocked the early effect of LPS on cortical activity. However, experiments under urethane anesthesia which were started 24 h post-LPS (with neuroinflammation fully developed before application of urethane) showed that both theta-supratheta and fast gamma CA1 activity were reduced, DG delta activity was increased, and sharp-wave ripples were abolished. Finally, we observed that experimental compensation of inflammation-induced hypothermia 24-48 h post-LPS promoted seizures and status epilepticus; and that LPS decreased the threshold of kainate-provoked seizures beyond the duration of acute sickness behavior indicating post-acute inflammatory hyperexcitability. Taken together, the strikingly fast development and initial independence of brain cytokines of the LPS-induced cortical mode, its spectral characteristics and simultaneity in hippocampus and neocortex, as well as inhibition by pre-applied urethane, strongly suggest that the underlying mechanisms are based on activation of the afferent vagus nerve and its mainly cholinergic ascending projections to higher brain areas.

A novel co-culture model for investigation of the effects of LPS-induced macrophage-derived cytokines on brain endothelial cells

In order to study effects of macrophage-derived inflammatory mediators associated with systemic inflammation on brain endothelial cells, we have established a co-culture system consisting of bEnd.3 cells and LPS-activated Raw 264.7 cells and performed its cytokine profiling. The cytokine profile of the co-culture model was compared to that of mice treated with intraperitoneal LPS injection. We found that, among cytokines profiled, eight cytokines/chemokines were similarly upregulated in both in vivo mouse and in vitro co-culture model. In contrast to the co-culture model, the cytokine profile of a common mono-culture system consisting of only LPS-activated bEnd.3 cells had little similarity to that of the in vivo mouse model. These results indicate that the co-culture of bEnd.3 cells with LPS-activated Raw 264.7 cells is a better model than the common mono-culture of LPS-activated bEnd.3 cells to investigate the molecular mechanism in endothelial cells, by which systemic inflammation induces neuroinflammation. Moreover, fibrinogen adherence both to bEnd.3 cells in the co-culture and to brain blood vessels in a LPS-treated animal model of Alzheimer's disease increased. To the best of our knowledge, this is the first to utilize bEnd.3 cells co-cultured with LPS-activated Raw 264.7 cells as an in vitro model to investigate the consequence of macrophage-derived inflammatory mediators on brain endothelial cells.

A Triterpenoid Lupeol as an Antioxidant and Anti-Neuroinflammatory Agent: Impacts on Oxidative Stress in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease illustrated by neuronal dysfunctions, leading to memory weaknesses and personality changes mostly in the aged population worldwide. The exact cause of AD is unclear, but numerous studies have addressed the involvement of oxidative stress (OS), induced by reactive oxygen species (ROS), to be one of the leading causes in developing AD. OS dysregulates the cellular homeostasis, causing abnormal protein and lipid metabolism. Nutrition plays a pivotal role in modulating the antioxidant system and decreases the neuronal ROS level, thus playing an important therapeutic role in neurodegenerative diseases, especially in AD. Hence, medicinal herbs and their extracts have received global attention as a commercial source of antioxidants Lupeol. Lupeol is a pentacyclic triterpenoid and has many biological functions. It is available in fruits, vegetables, and medicinal plants. It has shown effective antioxidant and anti-inflammatory properties, and higher blood-brain barrier permeability. Also, the binding and inhibitory potentials of Lupeol have been investigated and proved to be effective against certain receptor proteins and enzymes in AD studies by computational molecular docking approaches. Therefore, AD-related research has gained interest in investigating the therapeutic effects of Lupeol. However, despite its beneficial effects in AD, there is still a lack of research in Lupeol. Hence, we compiled in this analysis all preclinical research that looked at Lupeol as an antioxidant and anti-inflammatory agent for AD.