Imbalance of Circulating Th17 and Regulatory T Cells in Alzheimer's Disease: A Case Control Study

Rebuilding insight into the pathophysiology of Alzheimer's disease through new blood-brain barrier models

The blood-brain barrier is a unique function of the microvasculature in the brain parenchyma that maintains homeostasis in the central nervous system. Blood-brain barrier breakdown is a common pathology in various neurological diseases, such as Alzheimer's disease, stroke, multiple sclerosis, and Parkinson's disease. Traditionally, it has been considered a consequence of neuroinflammation or neurodegeneration, but recent advanced imaging techniques and detailed studies in animal models show that blood-brain barrier breakdown occurs early in the disease process and may precede neuronal loss. Thus, the blood-brain barrier is attractive as a potential therapeutic target for neurological diseases that lack effective therapeutics. To elucidate the molecular mechanism underlying blood-brain barrier breakdown and translate them into therapeutic strategies for neurological diseases, there is a growing demand for experimental models of human origin that allow for functional assessments. Recently, several human induced pluripotent stem cell-derived blood-brain barrier models have been established and various in vitro blood-brain barrier models using microdevices have been proposed. Especially in the Alzheimer's disease field, the human evidence for blood-brain barrier dysfunction has been demonstrated and human induced pluripotent stem cell-derived blood-brain barrier models have suggested the putative molecular mechanisms of pathological blood-brain barrier. In this review, we summarize recent evidence of blood-brain barrier dysfunction in Alzheimer's disease from pathological analyses, imaging studies, animal models, and stem cell sources. Additionally, we discuss the potential future directions for blood-brain barrier research.

All-Trans Retinoic Acid-Induced Cell Surface Heat Shock Protein 90 Mediates Tau Protein Internalization and Degradation in Human Microglia

This study investigates the role of all-trans retinoic acid (ATRA) in modulating the expression of heat shock protein 90 (Hsp90) and its influence on the uptake and degradation of tau proteins in immortalized human microglia cells. We demonstrate that ATRA significantly upregulates Hsp90 expression in a concentration-dependent manner, enhancing both extracellular and intracellular Hsp90 levels. Our results show that ATRA-treated cells exhibit increased tau protein uptake via caveolae/raft-dependent endocytosis pathways. This uptake is mediated by surface Hsp90, as evidenced by the inhibition of tau internalization using an extracellular Hsp90-selective inhibitor. Further, we establish that the exogenously added full-sized monomeric tau proteins bind to Hsp90. The study also reveals that ATRA-enhanced tau uptake is followed by effective degradation through both lysosomal and proteasomal pathways. We observed a significant reduction in intracellular tau levels in ATRA-treated cells, which was reversed by lysosome or proteasome inhibitors, suggesting the involvement of both degradation pathways. Our findings highlight the potential therapeutic role of ATRA in Alzheimer's disease and related tauopathies. By enhancing Hsp90 expression and facilitating tau degradation, ATRA could contribute to the clearance of pathological tau proteins, offering a promising strategy for mitigating neurodegeneration. This research underscores the need for further exploration into the molecular mechanisms of tau protein internalization and degradation, which could provide valuable insights into the treatment of neurodegenerative diseases.

Neuroinflammation in Alzheimer's disease: insights from peripheral immune cells

Alzheimer's disease (AD) is a serious brain disorder characterized by the presence of beta-amyloid plaques, tau pathology, inflammation, neurodegeneration, and cerebrovascular dysfunction. The presence of chronic neuroinflammation, breaches in the blood-brain barrier (BBB), and increased levels of inflammatory mediators are central to the pathogenesis of AD. These factors promote the penetration of immune cells into the brain, potentially exacerbating clinical symptoms and neuronal death in AD patients. While microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in AD, recent evidence suggests the infiltration of cerebral vessels and parenchyma by peripheral immune cells, including neutrophils, T lymphocytes, B lymphocytes, NK cells, and monocytes in AD. These cells participate in the regulation of immunity and inflammation, which is expected to play a huge role in future immunotherapy. Given the crucial role of peripheral immune cells in AD, this article seeks to offer a comprehensive overview of their contributions to neuroinflammation in the disease. Understanding the role of these cells in the neuroinflammatory response is vital for developing new diagnostic markers and therapeutic targets to enhance the diagnosis and treatment of AD patients.

Alterations in Immune Responses Are Associated with Dysfunctional Intracellular Signaling in Peripheral Blood Mononuclear Cells of Men and Women with Mild Cognitive Impairment and Alzheimer's disease

Deficits in the neuroendocrine-immune network in the periphery associated with the onset and progression of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have not been extensively studied. The present study correlatively examines the association between cell-mediated immune responses, stress hormones, amyloid precursor protein (APP) expression, peripheral blood mononuclear cells (PBMC), and intracellular signaling molecules in the pathophysiology of MCI and AD compared to adults. Serum APP, lymphocyte proliferation, total cholinesterase (TChE), butyrylcholinesterase (BChE) activities, cytokines (IL-2, IFN-γ, IL-6, and TNF-α), and intracellular signaling molecules (p-ERK, p-CREB, and p-Akt) were measured in the PBMCs of adult, old, MCI, and AD men and women initially and after 3 years in the same population. An age- and disease-associated decline in mini-mental state examination (MMSE) scores and lymphocyte proliferation of MCI and AD men and women were observed. An age- and disease-related increase in serum APP, cortisol levels, and TChE activity were observed in men and women. Enhanced production of Th1 cytokine, IL-2, pro-inflammatory cytokines, and suppressed intracellular transcription factors may promote the inflammatory environment in MCI and AD patients. The expression of CREB and Akt was lower in MCI and AD men, while the expression of p-ERK was higher, and p-CREB was lower in MCI and AD women after 3 years. These results suggest that changes in specific intracellular signaling pathways may influence alterations in cell-mediated immunity to promote disease progression in MCI and AD patients.

CD4+ T-Cell Senescence in Neurodegenerative Disease: Pathogenesis and Potential Therapeutic Targets

With the increasing proportion of the aging population, neurodegenerative diseases have become one of the major health issues in society. Neurodegenerative diseases (NDs), including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), are characterized by progressive neurodegeneration associated with aging, leading to a gradual decline in cognitive, emotional, and motor functions in patients. The process of aging is a normal physiological process in human life and is accompanied by the aging of the immune system, which is known as immunosenescence. T-cells are an important part of the immune system, and their senescence is the main feature of immunosenescence. The appearance of senescent T-cells has been shown to potentially lead to chronic inflammation and tissue damage, with some studies indicating a direct link between T-cell senescence, inflammation, and neuronal damage. The role of these subsets with different functions in NDs is still under debate. A growing body of evidence suggests that in people with a ND, there is a prevalence of CD4+ T-cell subsets exhibiting characteristics that are linked to senescence. This underscores the significance of CD4+ T-cells in NDs. In this review, we summarize the classification and function of CD4+ T-cell subpopulations, the characteristics of CD4+ T-cell senescence, the potential roles of these cells in animal models and human studies of NDs, and therapeutic strategies targeting CD4+ T-cell senescence.

The oral-brain axis: can periodontal pathogens trigger the onset and progression of Alzheimer's disease?

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a progressive cognitive decline. Sporadic AD, accounting for more than 95% of cases, may arise due to the influence of environmental factors. It was reported that periodontitis, a common oral ailment, shares several risk factors with AD, including advanced age, smoking, diabetes, and hypertension, among others. Periodontitis is an inflammatory disease triggered by dysbiosis of oral microorganisms, whereas Alzheimer's disease is characterized by neuroinflammation. Many studies have indicated that chronic inflammation can instigate brain AD-related pathologies, including amyloid-β plaques, Tau protein hyperphosphorylation, neuroinflammation, and neurodegeneration. The potential involvement of periodontal pathogens and/or their virulence factors in the onset and progression of AD by the oral-brain axis has garnered significant attention among researchers with ongoing investigations. This review has updated the periodontal pathogens potentially associated with AD, elucidating their impact on the central nervous system, immune response, and related pathological processes in the brain to provide valuable insights for future research on the oral-brain axis.

Acid sphingomyelinase as a pathological and therapeutic target in neurological disorders: focus on Alzheimer's disease

Over the past decade, numerous studies have highlighted the importance of acid sphingomyelinase (ASM) in disease treatment in humans. This enzyme functions primarily to generate ceramide, maintain the cellular membrane, and regulate cellular function. However, in the blood and brain of patients with neurological disorders, including major depression, ischemic stroke, amyotrophic lateral sclerosis, multiple sclerosis, and Alzheimer's disease (AD), elevated ASM levels significantly suggest disease onset or progression. In these diseases, increased ASM is profoundly involved in neuronal death, abnormal autophagy, neuroinflammation, blood-brain barrier disruption, hippocampal neurogenesis loss, and immune cell dysfunction. Moreover, genetic and pharmacological inhibition of ASM can prevent or ameliorate various diseases. The therapeutic effects of ASM inhibition have prompted the urgent need to develop ASM inhibitors, and several ASM inhibitors have been identified. In this review, we summarize the current knowledge on the critical roles and mechanisms of ASM in brain cells and blood that are associated with different neuropathological features, especially those observed in AD. Furthermore, we elucidate the potential possibility and limitations of existing ASM-targeting drugs according to experimental studies in neurological disorder mouse models.

Effects of Exercise Training on Immune-Related Genes and Pathways in the Cortex of Animal Models of Alzheimer's Disease: A Systematic Review

Background

Alzheimer's disease (AD) is a chronic neurodegenerative disease that affects the immune system due to the accumulation of amyloid-β (Aβ) and tau associated molecular pathology and other pathogenic processes. To address AD pathogenesis, various approaches had been conducted from drug development to lifestyle modification to reduce the prevalence of AD. Exercise is considered a prominent lifestyle modification to combat AD.

Objective

This observation prompted us to review the literature on exercise related to immune genes in the cortex of animal models of AD. We focused on animal model studies due to their prevalence in this domain.

Methods

The systematic review was conducted according to PRISMA standards using Web of Science (WoS) and PubMed databases. Any kind of genes, proteins, and molecular molecules were included in this systematic review. The list of these immune-related molecules was analyzed in the STRING database for functional enrichment analysis.

Results

We found that 17 research studies discussed immune-related molecules and 30 immune proteins. These studies showed that exercise had the ability to ameliorate dysfunction in AD-related pathways, which led to decreasing the expression of microglia-related pathways and Th17-related immune pathways. As a result of decreasing the expression of immune-related pathways, the expression of apoptosis-related pathways was also decreasing, and neuronal survival was increased by exercise activity.

Conclusions

Based on functional enrichment analysis, exercise not only could reduce apoptotic factors and immune components but also could increase cell survival and Aβ clearance in cortex samples. PROSPERO ID: CRD42022326093.

Nutrition, Immunity and Aging: Current Scenario and Future Perspectives in Neurodegenerative Diseases

Aging is a gradual decline of physiological function and tissue homeostasis and, in many instances, is related to increased (neuro)-degeneration, together with inflammation, becoming one of the most important risks for developing neurodegenerative diseases. Certain individual nutrients or foods in combination may counteract aging and associated neurodegenerative diseases by promoting a balance between the pro- and anti-inflammatory responses. Thus, nutrition could represent a powerful modulator of this fine balance, other than a modifiable risk factor to contrast inflammaging. This narrative review explores from a broad perspective the impact of nutrition on the hallmarks of aging and inflammation in Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis Syndrome (ALS), starting from nutrients up to single foods and complex dietary patterns.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.

Amyloid-β specific regulatory T cells attenuate Alzheimer's disease pathobiology in APP/PS1 mice

BACKGROUND

Regulatory T cells (Tregs) maintain immune tolerance. While Treg-mediated neuroprotective activities are now well-accepted, the lack of defined antigen specificity limits their therapeutic potential. This is notable for neurodegenerative diseases where cell access to injured brain regions is required for disease-specific therapeutic targeting and improved outcomes. To address this need, amyloid-beta (Aβ) antigen specificity was conferred to Treg responses by engineering the T cell receptor (TCR) specific for Aβ (TCRAβ). The TCRAb were developed from disease-specific T cell effector (Teff) clones. The ability of Tregs expressing a transgenic TCRAβ (TCRAβ -Tregs) to reduce Aβ burden, transform effector to regulatory cells, and reverse disease-associated neurotoxicity proved beneficial in an animal model of Alzheimer's disease.

METHODS

TCRAβ -Tregs were generated by CRISPR-Cas9 knockout of endogenous TCR and consequent incorporation of the transgenic TCRAb identified from Aβ reactive Teff monoclones. Antigen specificity was confirmed by MHC-Aβ-tetramer staining. Adoptive transfer of TCRAβ-Tregs to mice expressing a chimeric mouse-human amyloid precursor protein and a mutant human presenilin-1 followed measured behavior, immune, and immunohistochemical outcomes.

RESULTS

TCRAβ-Tregs expressed an Aβ-specific TCR. Adoptive transfer of TCRAβ-Tregs led to sustained immune suppression, reduced microglial reaction, and amyloid loads. 18F-fluorodeoxyglucose radiolabeled TCRAβ-Treg homed to the brain facilitating antigen specificity. Reduction in amyloid load was associated with improved cognitive functions.

CONCLUSIONS

TCRAβ-Tregs reduced amyloid burden, restored brain homeostasis, and improved learning and memory, supporting the increased therapeutic benefit of antigen specific Treg immunotherapy for AD.

Alzheimer's disease: The role of T lymphocytes in neuroinflammation and neurodegeneration

Alzheimer's disease, the leading cause of progressive cognitive decline globally, has been reported to be enhanced by neuroinflammation. Brain-resident innate immune cells and adaptive immune cells work together to produce neuroinflammation. Studies over the past decade have established the neuroimmune axis present in Alzheimer's disease; the crosstalk between adaptive and innate immune cells within and outside the brain is crucial to the onset and progression of Alzheimer's disease. Although the role of the adaptive immune system in Alzheimer's disease is not fully understood, it has been hypothesized that the brain's immune homeostasis is significantly disrupted, which greatly contributes to neuroinflammation. Brain-infiltrating T cells possess proinflammatory phenotypes and activities that directly contribute to neuroinflammation. The pro-inflammatory activities of the adaptive immune system in Alzheimer's disease are characterized by the upregulation of effector T cell activities and the downregulation of regulatory T cell activities in the brain, blood, and cerebrospinal fluid. In this review, we discuss the major impact of T lymphocytes on the pathogenesis and progression of Alzheimer's disease. Understanding the role and mechanism of action of T cells in Alzheimer's disease would significantly contribute to the identification of novel biomarkers for diagnosing and monitoring the progression of the disease. This knowledge could also be crucial to the development of immunotherapies for Alzheimer's disease.

Advances in the study of IL-17 in neurological diseases and mental disorders

Interleukin-17 (IL-17), a cytokine characteristically secreted by T helper 17 (Th17) cells, has attracted increasing attention in recent years because of its importance in the pathogenesis of many autoimmune or chronic inflammatory diseases. Recent studies have shown that neurological diseases and mental disorders are closely related to immune function, and varying degrees of immune dysregulation may disrupt normal expression of immune molecules at critical stages of neural development. Starting from relevant mechanisms affecting immune regulation, this article reviews the research progress of IL-17 in a selected group of neurological diseases and mental disorders (autism spectrum disorder, Alzheimer's disease, epilepsy, and depression) from the perspective of neuroinflammation and the microbiota-gut-brain axis, summarizes the commonalities, and provides a prospective outlook of target application in disease treatment.

Exploration of the shared genetic biomarkers in Alzheimer's disease and chronic kidney disease using integrated bioinformatics analysis

In order to investigate the potential link between Alzheimer's disease (AD) and chronic kidney disease (CKD), we conducted a comprehensive analysis using a bioinformatics approach. We downloaded AD and CKD datasets from the Gene Expression Omnibus database and analyzed differentially expressed genes and weighted gene co-expression networks to identify candidate genes for AD and CKD. We used a combination of the least absolute shrinkage and selection operator and random forest algorithms to select the shared genes. Subsequently, we shared genes and performed an immune infiltration analysis to investigate the association between different immune cell types and shared genes. Finally, we elucidated the relationship between the expression levels of the shared genes in disease samples and cells using single-cell analysis. Our analysis identified 150 candidate genes that may be primarily involved in immune inflammatory responses and energy metabolism pathways. We found that JunD Proto-Oncogene, ALF transcription elongation factor 1, and ZFP36 Ring Finger Protein Like 1 were the best co-diagnostic markers for AD and CKD based on the results of Least Absolute Shrinkage Selection Operator analysis and the random forest algorithm. Based on the results of immune infiltration analysis, macrophages and T-cells play a significant role in the progression of AD and CKD. Our scRNA-sequencing data showed that the 3 shared genes in AD were significantly expressed in astrocytes, excitatory neurons, oligodendrocytes, and MAIT cells. The 3 shared genes in CKD were significantly expressed in oligodendrocytes, neutrophils, fibroblasts, astrocytes, and T-cells. JunD Proto-Oncogene, ALF transcription elongation factor 1, and ZFP36 Ring Finger Protein Like 1 genes are the best diagnostic markers for AD and CKD.

Differential roles of regulatory T cells in Alzheimer's disease

Regulatory T (Treg) cells interact with a variety of resident cells and infiltrated immune cells in the central nervous system (CNS) to modulate neuroinflammation and neurodegeneration. Extracellular amyloid-β (Aβ) peptide deposition and secondary persistent inflammation due to activation of microglia, astrocytes, and infiltrated immune cells contribute to Alzheimer's disease (AD)-related neurodegeneration. The majority of evidence supports the neuroprotective effects of Treg cells in AD. In the early stages of AD, appropriate Treg cell activity is required for the induction of microglia and astrocyte phagocytic activity in order to clear A deposits and prevent neuroinflammation. Such neuroprotective impacts were in part attributed to the ability of Treg cells to suppress deleterious and/or boost beneficial functions of microglia/astrocytes. In the later stages of AD, an effective Treg cell activity needs to prevent neurotoxicity and neurodegeneration. Treg cells can exert preventive effects on Th1-, and Th17 cell-related pathologic responses, whilst potentiating Th2-mediated protective activity. The impaired Treg cell-related immunomodulatory mechanisms have been described in AD patients and in related animal models which can contribute to the onset and progression of AD. This review aimed to provide a comprehensive figure regarding the role of Treg cells in AD while highlighting potential therapeutic approaches.

[Identification of Peripheral Blood GZMK + CD8 + T Cells As Biomarkers of Alzheimer's Disease Based on Single-Cell Transcriptome]

Objective

Based on single-cell RNA sequencing (scRNA-seq) to explore immune characteristics in the peripheral blood of patients with Alzheimer's disease (AD) as biomarkers.

Methods

GSE168522, the scRNA-seq dataset of AD peripheral blood immune cells, was downloaded from the Gene Expression Omnibus (GEO) database and was analyzed in the RAD-Blood web server (http://www.bioinform.cn/RAD-Blood/). The changes in blood cell composition in AD patients were analyzed. The abnormal communications between different types of cells in AD patients were investigated by the CellChat R package.

Results

There were two kinds of CD8 + T cells in the blood of AD patients and healthy individuals, one of which highly expressed granzyme K ( GZMK) (false discovery rate [FDR]<0.05), and the other highly expressed GZMA, GZMB, and GZMH (FDR<0.05). In the blood of AD patients, the content of GZMK + CD8 + T cells was increased by 32.9% ( P=5.15E-21), their interactions with other cell types were increased, and they might be associated with AD through the abnormal signal transduction of major histocompatibility complex class Ⅰ (MHC-Ⅰ). Erythrocyte provided the main ligands, that are, human leukocyte antigen (HLA) class Ⅰ molecules, including HLA- A, HLA- B, HLA- C, and HLA- E, for the abnormal MHC-Ⅰ signaling pathway of GZMK + CD8 + T cells. The RESISTIN signaling pathway was specifically enriched in the blood of AD patients.

Conclusion

The increased content of peripheral blood GZMK + CD8 + T cells, the increased interaction between GZMK + CD8 + T cells and erythrocytes, and the enhanced RESISTIN pathway are potential blood biomarkers of AD.

Sex-based differences in effector cells of the adaptive immune system during Alzheimer's disease and related dementias

Neurological conditions such as Alzheimer's disease (AD) and related dementias (ADRD) present with many challenges due to the heterogeneity of the related disease(s), making it difficult to develop effective treatments. Additionally, the progression of ADRD-related pathologies presents differently between men and women. With two-thirds of the population affected with ADRD being women, ADRD has presented itself with a bias toward the female population. However, studies of ADRD generally do not incorporate sex-based differences in investigating the development and progression of the disease, which is detrimental to understanding and treating dementia. Additionally, recent implications for the adaptive immune system in the development of ADRD bring in new factors to be considered as part of the disease, including sex-based differences in immune response(s) during ADRD development. Here, we review the sex-based differences of pathological hallmarks of ADRD presentation and progression, sex-based differences in the adaptive immune system and how it changes with ADRD, and the importance of precision medicine in the development of a more targeted and personalized treatment for this devastating and prevalent neurodegenerative condition.

Age- and sex-related differences of periodontal bone resorption, cognitive function, and immune state in APP/PS1 murine model of Alzheimer's disease

BACKGROUND

The existence of an interconnected mechanism between cognitive disorders and periodontitis has been confirmed by mounting evidence. However, the role of age or sex differences in this mechanism has been less studied. This study aims to investigate sex and age differences in the characterization of periodontal bone tissue, immune state and cognitive function in amyloid precursor protein/presenilin 1(APP/PS1) murine model of Alzheimer's disease (AD).

METHODS

Three- and twelve-month-old male and female APP/PS1 transgenic mice and wild-type (WT) littermates were used in this study. The Morris water maze (MWM) was used to assess cognitive function. The bone microarchitecture of the posterior maxillary alveolar bone was evaluated by microcomputed tomography (micro-CT). Pathological changes in periodontal bone tissue were observed by histological chemistry. The proportions of helper T cells1 (Th1), Th2, Th17 and regulatory T cells (Tregs) in the peripheral blood mononuclear cells (PBMCs) and brain samples were assessed by flow cytometry.

RESULTS

The learning ability and spatial memory of 12-month-old APP/PS1 mice was severely damaged. The changes in cognitive function were only correlated with age and genotype, regardless of sex. The 12-month-old APP/PS1 female mice exhibited markedly periodontal bone degeneration, evidenced by the decreased bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), and bone mineral density (BMD), and the increased trabecular separation (Tb.Sp). The altered periodontal bone microarchitecture was associated with genotype, age and females. The flow cytometry data showed the increased Th1 and Th17 cells and the decreased Th2 cells in the brain and PBMC samples of 12-month-old APP/PS1 mice, compared to age- and sex-matched WT mice. However, there was no statistical correlation between age or sex and this immune state.

CONCLUSIONS

Our data emphasize that age and sex are important variables to consider in evaluating periodontal bone tissue of APP/PS1 mice, and the cognitive impairment is more related to age. In addition, immune dysregulation (Th1, Th2, and Th17 cells) was found in the brain tissue and PBMCs of APP/PS1 mice, but this alteration of immune state was not statistically correlated with sex or age.

Mild Cognitive Impairment Is Associated with Enhanced Activation of Th17 Lymphocytes in Non-Alcoholic Fatty Liver Disease

Patients with nonalcoholic fatty liver disease (NAFLD) may show mild cognitive impairment (MCI). The mechanisms involved remain unclear. The plasma concentrations of several cytokines and chemokines were measured in 71 NAFLD patients (20 with and 51 without MCI) and 61 controls. Characterization and activation of leukocyte populations and CD4⁺ sub-populations were carried out and analyzed by flow cytometry. We analyzed the cytokines released from CD4⁺ cell cultures and the mRNA expression of transcription factors and receptors in peripheral blood mononuclear cells. The appearance of MCI in NAFLD patients was associated with increased activation of CD4⁺ T lymphocytes, mainly of the Th17 subtype, increased plasma levels of pro-inflammatory and anti-inflammatory cytokines such as IL-17A, IL-23, IL-21, IL-22, IL-6, INF-γ, and IL-13, and higher expression of the CCR2 receptor. Constitutive expression of IL-17 was found in cultures of CD4⁺ cells from MCI patients, reflecting Th17 activation. High IL-13 plasma levels were predictive of MCI and could reflect a compensatory anti-inflammatory response to the increased expression of pro-inflammatory cytokines. This study identified some specific alterations of the immune system associated with the appearance of neurological alterations in MCI patients with NAFLD that could be the basis to improve and restore cognitive functions and quality of life in these patients.

An open-label multiyear study of sargramostim-treated Parkinson's disease patients examining drug safety, tolerability, and immune biomarkers from limited case numbers

BACKGROUND

The clinical utility and safety of sargramostim has previously been reported in cancer, acute radiation syndrome, autoimmune disease, inflammatory conditions, and Alzheimer's disease. The safety, tolerability, and mechanisms of action in Parkinson's disease (PD) during extended use has not been evaluated.

METHODS

As a primary goal, safety and tolerability was assessed in five PD patients treated with sargramostim (Leukine®, granulocyte-macrophage colony-stimulating factor) for 33 months. Secondary goals included numbers of CD4+ T cells and monocytes and motor functions. Hematologic, metabolic, immune, and neurological evaluations were assessed during a 5-day on, 2-day off therapeutic regimen given at 3 μg/kg. After 2 years, drug use was discontinued for 3 months. This was then followed by an additional 6 months of treatment.

RESULTS

Sargramostim-associated adverse events included injection-site reactions, elevated total white cell counts, and bone pain. On drug, blood analyses and metabolic panels revealed no untoward side effects linked to long-term treatment. Unified Parkinson's Disease Rating Scale scores remained stable throughout the study while regulatory T cell number and function were increased. In the initial 6 months of treatment, transcriptomic and proteomic monocyte tests demonstrated autophagy and sirtuin signaling. This finding paralleled anti-inflammatory and antioxidant activities within both the adaptive and innate immune profile arms.

CONCLUSIONS

Taken together, the data affirmed long-term safety as well as immune and anti-inflammatory responses reflecting clinical stability in PD under the sargramostim treatment. Confirmation in larger patient populations is planned in a future phase II evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03790670, Date of Registration: 01/02/2019, URL: https://clinicaltrials.gov/ct2/show/NCT03790670?cond=leukine+parkinson%27s&draw=2&rank=2 .

T cell aging and Alzheimer’s disease

The brain has long been considered an immune-privileged organ due to the presence of the blood-brain barrier (BBB). However, recent discoveries have revealed the underestimated role of T cells in the brain through the meningeal lymphatic system. Age is the primary risk factor for Alzheimer’s disease (AD), resulting in marked age-dependent changes in T cells. Manipulating peripheral T cell immune response has been shown to impact AD, but the relationship between T cell aging and AD remains poorly understood. Given the limited success of targeting amyloid beta (Aβ) and the growing evidence of T cells’ involvement in non-lymphoid organ aging, a deeper understanding of the relationship between T cells and AD in the context of aging is crucial for advancing therapeutic progress. In this review, we comprehensively examine existing studies on T cells and AD and offer an integrated perspective on their interconnections in the context of aging. This understanding can inform the development of new interventions to prevent or treat AD.

Immunotherapy targeting plasma ASM is protective in a mouse model of Alzheimer's disease

Acid sphingomyelinase (ASM) has been implicated in neurodegenerative disease pathology, including Alzheimer's disease (AD). However, the specific role of plasma ASM in promoting these pathologies is poorly understood. Herein, we explore plasma ASM as a circulating factor that accelerates neuropathological features in AD by exposing young APP/PS1 mice to the blood of mice overexpressing ASM, through parabiotic surgery. Elevated plasma ASM was found to enhance several neuropathological features in the young APP/PS1 mice by mediating the differentiation of blood-derived, pathogenic Th17 cells. Antibody-based immunotherapy targeting plasma ASM showed efficient inhibition of ASM activity in the blood of APP/PS1 mice and, interestingly, led to prophylactic effects on neuropathological features by suppressing pathogenic Th17 cells. Our data reveals insights into the potential pathogenic mechanisms underlying AD and highlights ASM-targeting immunotherapy as a potential strategy for further investigation.

Immune Regulatory Functions of Macrophages and Microglia in Central Nervous System Diseases

Macrophages can be characterized as a very multifunctional cell type with a spectrum of phenotypes and functions being observed spatially and temporally in various disease states. Ample studies have now demonstrated a possible causal link between macrophage activation and the development of autoimmune disorders. How these cells may be contributing to the adaptive immune response and potentially perpetuating the progression of neurodegenerative diseases and neural injuries is not fully understood. Within this review, we hope to illustrate the role that macrophages and microglia play as initiators of adaptive immune response in various CNS diseases by offering evidence of: (1) the types of immune responses and the processes of antigen presentation in each disease, (2) receptors involved in macrophage/microglial phagocytosis of disease-related cell debris or molecules, and, finally, (3) the implications of macrophages/microglia on the pathogenesis of the diseases.

The potential for treg-enhancing therapies in nervous system pathologies

While inflammation may not be the cause of disease, it is well known that it contributes to disease pathogenesis across a multitude of peripheral and central nervous system disorders. Chronic and overactive inflammation due to an effector T-cell-mediated aberrant immune response ultimately leads to tissue damage and neuronal cell death. To counteract peripheral and neuroinflammatory responses, research is being focused on regulatory T cell enhancement as a therapeutic target. Regulatory T cells are an immunosuppressive subpopulation of CD4+ T helper cells essential for maintaining immune homeostasis. The cells play pivotal roles in suppressing immune responses to maintain immune tolerance. In so doing, they control T cell proliferation and pro-inflammatory cytokine production curtailing autoimmunity and inflammation. For nervous system pathologies, Treg are known to affect the onset and tempo of neural injuries. To this end, we review recent findings supporting Treg's role in disease, as well as serving as a therapeutic agent in multiple sclerosis, myasthenia gravis, Guillain-Barre syndrome, Parkinson's and Alzheimer's diseases, and amyotrophic lateral sclerosis. An ever-broader role for Treg in the control of neurologic disease has been shown for traumatic brain injury, stroke, neurotrophic pain, epilepsy, and psychiatric disorders. To such ends, this review serves to examine the role played by Tregs in nervous system diseases with a focus on harnessing their functional therapeutic role(s).

N-acetylneuraminic acid links immune exhaustion and accelerated memory deficit in diet-induced obese Alzheimer's disease mouse model

Systemic immunity supports lifelong brain function. Obesity posits a chronic burden on systemic immunity. Independently, obesity was shown as a risk factor for Alzheimer's disease (AD). Here we show that high-fat obesogenic diet accelerated recognition-memory impairment in an AD mouse model (5xFAD). In obese 5xFAD mice, hippocampal cells displayed only minor diet-related transcriptional changes, whereas the splenic immune landscape exhibited aging-like CD4+ T-cell deregulation. Following plasma metabolite profiling, we identified free N-acetylneuraminic acid (NANA), the predominant sialic acid, as the metabolite linking recognition-memory impairment to increased splenic immune-suppressive cells in mice. Single-nucleus RNA-sequencing revealed mouse visceral adipose macrophages as a potential source of NANA. In vitro, NANA reduced CD4+ T-cell proliferation, tested in both mouse and human. In vivo, NANA administration to standard diet-fed mice recapitulated high-fat diet effects on CD4+ T cells and accelerated recognition-memory impairment in 5xFAD mice. We suggest that obesity accelerates disease manifestation in a mouse model of AD via systemic immune exhaustion.

Proinflammatory IL-17 levels in serum/cerebrospinal fluid of patients with neurodegenerative diseases: a meta-analysis study

IL-17 is one of the major proinflammatory cytokine implicated in the pathophysiology of various chronic inflammatory diseases. However, a clear association between the levels of IL-17 and various neurodegenerative diseases is inconclusive due to lack of consistent results reported in several studies. Therefore, we designed and performed a meta-analysis study to assess the levels of IL-17 cytokine in various neurodegenerative diseases. The aim of this meta-analysis study was to assess the level of IL-17 in cerebrospinal fluid/serum of the patients with neurodegenerative diseases such as Alzheimer's disease, Parkinson disease, multiple sclerosis, and amyotrophic lateral sclerosis. An extensive search was performed on electronic databases including PubMed, Cochrane, and Google Scholar to find out the relevant studies for analysis. The quality of selected studies was assessed by Newcastle-Ottawa scale for cohort and case control studies. The standardized mean difference of level of IL-17 in patients with neurodegenerative diseases and control was calculated using RevMan 5 software. A significant increase in the level of serum IL-17 was found to in the patients with neurodegenerative diseases like Alzheimer's disease (p = 0.001) and amyotrophic lateral sclerosis (p = 0.009), whereas IL-17 level in serum of Parkinson's disease (p = 0.22), multiple sclerosis (p = 0.09), and in peripheral blood mononuclear cells of MS patients (p = 0.34) was not found to be significant. IL-17 may be involved in regulation of neuronal inflammation during the pathogenesis of these neurodegenerative disease, and its specific inhibition could be a potential therapeutic target.

PR-957 Suppresses Th1 and Th17 Cell Differentiation via Inactivating PI3K/AKT Pathway in Alzheimer's Disease

PR-957 [low molecular mass polypeptide (LMP)-7 selective inhibitor] regulates T helper (Th) cell differentiation and inflammatory response in multiple neurological diseases. Hence, this study aimed to explore the effect of PR-957 on Th1/Th2/Th17 cell differentiation, therapeutic efficacy and its potential mechanisms in Alzheimer's disease (AD). The LMP7 expressions in peripheral blood mononuclear cells from 30 AD patients and 30 healthy controls (HC) were detected. PR-957 was added for the incubation of naive cluster of differentiation (CD)4⁺ T cells from AD patients, then SC79 [phosphorylated protein kinase B (pAKT) agonist] was added. LMP7, Th1 cells, and Th17 cells were upregulated, while Th2 cells were downregulated in AD patients compared to HC. Also, LMP7 was positively related to Th1 cells and Th17 cells, but it did not correlate with Th2 cells in AD patients. PR-957 treatment downregulated Th1 cells, Th17 cells, and their secreted cytokines as well as phosphorylated phosphoinositide 3-kinase (pPI3K)/PI3K and pAKT/AKT expressions in AD CD4⁺ T cells. SC79 addition upregulated pAKT/AKT expression, Th1 cells, and Th17 cells, while downregulated Th2 cells; also SC79 could alleviate the effect of PR-957 on regulating PI3K/AKT pathway and Th1, Th2, and Th17 cell differentiation in AD CD4⁺ T cells. Furthermore, PR-957 attenuated cognitive impairment and neurofibrillary tangle; also it inhibited Th17 cell differentiation and PI3K/AKT pathway in the brain and spleen of AD mice. In conclusion, PR-957 suppresses Th1 and Th17 cell differentiation, attenuates neural injury and improves cognitive function via inactivating PI3K/AKT pathway in AD.

The Development of Systemic Inflammatory Diseases in Hidradenitis Suppurativa

It is understood that the skin is a peripheral lymphoid tissue that defends against external environmental stimuli. Continuous activation from these factors, on the other hand, promotes persistent inflammation at the local location and, occasionally, tissue damage. Hidradenitis suppurativa (HS) is a typical inflammatory skin disease and becomes a source of numerous inflammatory cytokines due to the chronic intractable repeated inflamed tissues. Because inflammatory cells and cytokines circulate throughout the body from the inflamed organ, it has been hypothesized that HS-mediated skin inflammation impacts the systemic functioning of numerous organs. Recent updates to clinical and experimental investigations revealed that HS has a significant connection with systemic inflammatory disorders. We provide the details and comprehensive molecular mechanisms associated with systemic inflammatory illnesses due to HS.

Molecular Mechanisms of Neuroinflammation in Aging and Alzheimer's Disease Progression

Aging is the most prominent risk factor for late-onset Alzheimer's disease. Aging associates with a chronic inflammatory state both in the periphery and in the central nervous system, the evidence thereof and the mechanisms leading to chronic neuroinflammation being discussed. Nonetheless, neuroinflammation is significantly enhanced by the accumulation of amyloid beta and accelerates the progression of Alzheimer's disease through various pathways discussed in the present review. Decades of clinical trials targeting the 2 abnormal proteins in Alzheimer's disease, amyloid beta and tau, led to many failures. As such, targeting neuroinflammation via different strategies could prove a valuable therapeutic strategy, although much research is still needed to identify the appropriate time window. Active research focusing on identifying early biomarkers could help translating these novel strategies from bench to bedside.

A Cocktail of Polyherbal Bioactive Compounds and Regular Mobility Training as Senolytic Approaches in Age-dependent Alzheimer's: the In Silico Analysis, Lifestyle Intervention in Old Age

Alzheimer's is a principal concern globally. Machine learning is a valuable tool to determine protective and diagnostic approaches for the elderly. We analyzed microarray datasets of Alzheimer's cases based on artificial intelligence by R statistical software. This study provided a screened pool of ncRNAs and coding RNAs related to Alzheimer's development. We designed hub genes as cut points in networks and predicted potential microRNAs and LncRNA to regulate protein networks in aging and Alzheimer's through in silico algorithms. Notably, we collected effective traditional herbal medicines. A list of bioactive compounds prepared including capsaicin, piperine, crocetin, safranal, saffron oil, coumarin, thujone, rosmarinic acid, sabinene, thymoquinone, ascorbic acid, vitamin E, cyanidin, rhaponticin, isovitexin, coumarin, nobiletin, evodiamine, gingerol, curcumin, quercetin, fisetin, and allicin as an effective fusion that potentially modulates hub proteins and molecular signaling pathways based on pharmacophore model screening and chemoinformatics survey. We identified profiles of 21 mRNAs, 272 microRNAs, and eight LncRNA in Alzheimer's based on prediction algorithms. We suggested a fusion of senolytic herbal ligands as an alternative therapy and preventive formulation in dementia. Also, we provided ncRNAs expression status as novel monitoring strategies in Alzheimer's and new cut-point proteins as novel therapeutic approaches. Synchronizing fusion drugs and lifestyle could reverse Alzheimer's hallmarks to amelioration via an offset of the signaling pathways, leading to increased life quality in the elderly.

Grape Seed Extract Attenuates Demyelination in Experimental Autoimmune Encephalomyelitis Mice by Inhibiting Inflammatory Response of Immune Cells

OBJECTIVE

To examine the anti-inflammatory effect of grape seed extract (GSE) in animal and cellular models and explore its mechanism of action.

METHODS

This study determined the inhibitory effect of GSE on macrophage inflammation and Th1 and Th17 polarization in vitro. Based on the in vitro results, the effects and mechanisms of GSE on multiple sclerosis (MS)-experimental autoimmune encephalomyelitis (EAE) mice model were further explored. The C57BL/6 mice were intragastrically administered with 50 mg/kg of GSE once a day from the 3rd day to the 27th day after immunization. The activation of microglia, the polarization of Th1 and Th17 and the inflammatory factors such as tumor necrosis factor- α (TNF- α), interleukin-1 β (IL-1 β), IL-6, IL-12, IL-17 and interferon-γ (IFN-γ) secreted by them were detected in vitro and in vivo by flow cytometry, enzyme linked immunosorbent assay (ELISA), immunofluorescence staining and Western blot, respectively.

RESULTS

GSE reduced the secretion of TNF-α, IL-1 β and IL-6 in bone marrow-derived macrophages stimulated by lipopolysaccharide (P<0.01), inhibited the secretion of TNF-α, IL-1 β, IL-6, IL-12, IL-17 and IFN-γ in spleen cells of EAE mice immunized for 9 days (P<0.05 or P<0.01), and reduced the differentiation of Th1 and Th17 mediated by CD3 and CD28 factors (P<0.01). GSE significantly improved the clinical symptoms of EAE mice, and inhibited spinal cord demyelination and inflammatory cell infiltration. Peripherally, GSE downregulated the expression of toll-like-receptor 4 (TLR4) and Rho-associated kinase (ROCKII, P<0.05 or P<0.01), and inhibited the secretion of inflammatory factors (P<0.01 or P<0.05). In the central nervous system, GSE inhibited the infiltration of CD45⁺CD11b⁺ and CD45⁺CD4⁺ cells, and weakened the differentiation of Th1 and Th17 (P<0.05). Moreover, it reduced the secretion of inflammatory factors (P<0.01), and prevented the activation of microglia (P<0.05).

CONCLUSION

GSE had a beneficial effect on the pathogenesis and progression of EAE by inhibiting inflammatory response as a potential drug and strategy for the treatment of MS.

Magnesium and the Brain: A Focus on Neuroinflammation and Neurodegeneration

Magnesium (Mg) is involved in the regulation of metabolism and in the maintenance of the homeostasis of all the tissues, including the brain, where it harmonizes nerve signal transmission and preserves the integrity of the blood-brain barrier. Mg deficiency contributes to systemic low-grade inflammation, the common denominator of most diseases. In particular, neuroinflammation is the hallmark of neurodegenerative disorders. Starting from a rapid overview on the role of magnesium in the brain, this narrative review provides evidences linking the derangement of magnesium balance with multiple sclerosis, Alzheimer's, and Parkinson's diseases.

Alzheimer’s Disease: From Immune Homeostasis to Neuroinflammatory Condition

Alzheimer’s Disease is the most common cause in the world of progressive cognitive decline. Although many modifiable and non-modifiable risk factors have been proposed, in recent years, neuroinflammation has been hypothesized to be an important contributing factor of Alzheimer’s Disease pathogenesis. Neuroinflammation can occur through the combined action of the Central Nervous System resident immune cells and adaptive peripheral immune system. In the past years, immunotherapies for neurodegenerative diseases have focused wrongly on targeting protein aggregates Aβ plaques and NFT treatment. The role of both innate and adaptive immune cells has not been fully clarified, but several data suggest that immune system dysregulation plays a key role in neuroinflammation. Recent studies have focused especially on the role of the adaptive immune system and have shown that inflammatory markers are characterized by increased CD4+ Teff cells’ activities and reduced circulating CD4+ Treg cells. In this review, we discuss the key role of both innate and adaptive immune systems in the degeneration and regeneration mechanisms in the pathogenesis of Alzheimer’s Disease, with a focus on how the crosstalk between these two systems is able to sustain brain homeostasis or shift it to a neurodegenerative condition.

Association between inflammatory biomarkers and cognitive aging

Inflammatory cytokines and chemokines related to the innate and adaptive immune system have been linked to neuroinflammation in Alzheimer's Disease, dementia, and cognitive disorders. We examined the association of 11 plasma proteins (CD14, CD163, CD5L, CD56, CD40L, CXCL16, SDF1, DPP4, SGP130, sRAGE, and MPO) related to immune and inflammatory responses with measures of cognitive function, brain MRI and dementia risk. We identified Framingham Heart Study Offspring participants who underwent neuropsychological testing (n = 2358) or brain MRI (n = 2100) within five years of the seventh examination where a blood sample for quantifying the protein biomarkers was obtained; and who were followed for 10 years for incident all-cause dementia (n = 1616). We investigated the association of inflammatory biomarkers with neuropsychological test performance and brain MRI volumes using linear mixed effect models accounting for family relationships. We further used Cox proportional hazards models to examine the association with incident dementia. False discovery rate p-values were used to account for multiple testing. Participants included in the neuropsychological test and MRI samples were on average 61 years old and 54% female. Participants from the incident dementia sample (average 68 years old at baseline) included 124 participants with incident dementia. In addition to CD14, which has an established association, we found significant associations between higher levels of CD40L and myeloperoxidase (MPO) with executive dysfunction. Higher CD5L levels were significantly associated with smaller total brain volumes (TCBV), whereas higher levels of sRAGE were associated with larger TCBV. Associations persisted after adjustment for APOE ε4 carrier status and additional cardiovascular risk factors. None of the studied inflammatory biomarkers were significantly associated with risk of incident all-cause dementia. Higher circulating levels of soluble CD40L and MPO, markers of immune cell activation, were associated with poorer performance on neuropsychological tests, while higher CD5L, a key regulator of inflammation, was associated with smaller total brain volumes. Higher circulating soluble RAGE, a decoy receptor for the proinflammatory RAGE/AGE pathway, was associated with larger total brain volume. If confirmed in other studies, this data indicates the involvement of an activated immune system in abnormal brain aging.

Thymidine and 2'-deoxyuridine reduce microglial activation and improve oxidative stress damage by modulating glycolytic metabolism on the Aβ25-35-induced brain injury

Alzheimer's disease (AD) is a progressive disease with a long duration and complicated pathogenesis. Thymidine (Thy) and 2'-deoxyuridine (2'-De) are pyrimidines nucleotides that are associated with nervous system diseases. However, it remains unclear whether Thy and 2'-De exert neuroprotective effects in AD. Therefore, this study was conducted to explore the interventional effects and mechanisms of Thy and 2'-De on the Aβ_25-35-induced brain injury. Donepezil (Do, 10 mg/kg/d), Thy (20 mg/kg/d), and 2'-De (20 mg/kg/d) were administered for 4 weeks after the injection of Aβ_25-35 peptides (200 μM, i.c.v.) to mice. UPLC-MS/MS method was performed to quantify Thy and 2'-De in the hippocampus of mice brain. The cognition ability, neuronal and mitochondria damage, and levels of Aβ_1-42/Aβ_1-40, p-Tau, Na⁺ K⁺-ATPase, apoptosis, oxidative stress, immune cells, and Iba 1⁺ were measured in Aβ_25-35-induced mice. The oxygen consumption (OCR) and extracellular acidification rate (ECAR) were measured using a seahorse analyzer in Aβ_25-35-induced N9 cells. Moreover, 2-Deoxy-D-glucose (2-DG), a glycolysis inhibitor, was added to explore the mechanisms underlying the effects of Thy and 2'-De on Aβ_25-35-induced N9 cells. The expression of Iba 1⁺ and levels of CD11b⁺ and reactive oxygen species (ROS) were measured after treatment with Thy (5 μM) and 2'-De (10 μM) against 2-DG (5 mM) in Aβ_25-35-induced N9 cells. The results suggested that Do, Thy, and 2'-De improved the cognition ability, attenuated the damage to hippocampus and mitochondria, downregulated the levels of Aβ_1-42/Aβ_1-40, p-Tau, Na⁺ K⁺-ATPase, apoptosis, oxidative stress, and Iba 1⁺, and regulated the immune response induced by Aβ_25-35 against the brain injury. Furthermore, Do, Thy, and 2'-De increased ATP production and inhibited glycolysis in Aβ_25-35-induced N9 cells. Moreover, 2-DG enhanced the effects of drugs, reduced microglial activation, and attenuated oxidative stress to interfere with Aβ_25-35-induced N9 cells. In conclusion, Thy and 2'-De reduced microglial activation and improved oxidative stress damage by modulating glycolytic metabolism on the Aβ_25-35-induced brain injury.

Spontaneous and induced adaptive immune responses in Alzheimer's disease: new insights into old observations

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Although AD is primarily a neurological disorder distinguished by amyloid β plaques and intracellular neurofibrillary tangles, the immune system can impact the progression of the disease and may be targeted for therapeutic purposes. To date, most studies have focused on innate immune responses of microglia. However, emerging evidence implicates adaptive immune responses by T cells and B cells in the progression of AD. Moreover, the recent approval of an antibody that promotes amyloid β plaque clearance for AD therapy has pinpointed adaptive immunity as a fertile ground for the design of novel therapeutic approaches. Here, we highlight key studies delineating T cell and B cell responses in human AD and mouse models of AD, identify open questions on the specificity, development and impact of these responses and discuss outlooks for future studies and novel therapeutic avenues.

p38α‐MAPK‐deficient myeloid cells ameliorate symptoms and pathology of APP ‐transgenic Alzheimer's disease mice

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is pathologically characterized by extracellular deposition of amyloid‐β peptides (Aβ) and microglia‐dominated inflammatory activation in the brain. p38α‐MAPK is activated in both neurons and microglia. How p38α‐MAPK in microglia contributes to AD pathogenesis remains unclear. In this study, we conditionally knocked out p38α‐MAPK in all myeloid cells or specifically in microglia of APP‐transgenic mice, and examined animals for AD‐associated pathologies (i.e., cognitive deficits, Aβ pathology, and neuroinflammation) and individual microglia for their inflammatory activation and Aβ internalization at different disease stages (e.g., at 4 and 9 months of age). Our experiments showed that p38α‐MAPK‐deficient myeloid cells were more effective than p38α‐MAPK‐deficient microglia in reducing cerebral Aβ and neuronal impairment in APP‐transgenic mice. Deficiency of p38α‐MAPK in myeloid cells inhibited inflammatory activation of individual microglia at 4 months but enhanced it at 9 months. Inflammatory activation promoted microglial internalization of Aβ. Interestingly, p38α‐MAPK‐deficient myeloid cells reduced IL‐17a‐expressing CD4‐positive lymphocytes in 9 but not 4‐month‐old APP‐transgenic mice. By cross‐breeding APP‐transgenic mice with Il‐17a‐knockout mice, we observed that IL‐17a deficiency potentially activated microglia and reduced Aβ deposition in the brain as shown in 9‐month‐old myeloid p38α‐MAPK‐deficient AD mice. Thus, p38α‐MAPK deficiency in all myeloid cells, but not only in microglia, prevents AD progression. IL‐17a‐expressing lymphocytes may partially mediate the pathogenic role of p38α‐MAPK in peripheral myeloid cells. Our study supports p38α‐MAPK as a therapeutic target for AD patients.

Immune Response at the Crossroads of Atherosclerosis and Alzheimer's Disease

Alzheimer's disease (AD) and cardiovascular disease (CVD) are pathologies that are characterized by common signatures of vascular dysfunction and chronic inflammation that are accelerated with aging. Importantly, epidemiological studies report an independent interaction between AD and CVD and data suggest that chronic inflammation in CVD may accelerate AD development. Atherosclerosis affects most large to medium sized arteries including those supplying the cerebral circulation. Vascular dysfunction caused by atherosclerosis results in blood brain barrier breakdown, inflammation, an impaired clearance of amyloid-beta (Aβ), and finally ends with neurovascular dysfunction. Numerous data indicate that innate and adaptive immune responses shape atherogenesis and increasing evidence suggests an implication of the immune response in AD progression. Currently, mechanisms by which these two diseases are interconnected with each other are not well-defined. In this review, we discuss the recent advances in our understanding of the intertwined role of the immune response in atherosclerosis and AD and the implications of these findings for human health.

Crossing borders in Alzheimer's disease: A T cell's perspective

Alzheimer's disease (AD) is the most common form of dementia affecting millions of people worldwide. While different immunotherapies are imminent, currently only disease-modifying medications are available and a cure is lacking. Over the past decade, immunological interfaces of the central nervous system (CNS) and their role in neurodegenerative diseases received increasing attention. Specifically, emerging evidence shows that subsets of circulating CD8⁺ T cells cross the brain barriers and associate with AD pathology. To gain more insight into how the adaptive immune system is involved in disease pathogenesis, we here provide a comprehensive overview of the contribution of T cells to AD pathology, incorporating changes at the brain barriers. In addition, we review studies that provide translation of these findings by targeting T cells to combat AD pathology and cognitive decline. Importantly, these data show that immunological changes in AD are not confined to the CNS and that AD-associated systemic immune changes appear to affect brain homeostasis.

Emerging Roles of T Helper Cells in Non-Infectious Neuroinflammation: Savior or Sinner

CD4⁺ T cells, also known as T helper (Th) cells, contribute to the adaptive immunity both in the periphery and in the central nervous system (CNS). At least seven subsets of Th cells along with their signature cytokines have been identified nowadays. Neuroinflammation denotes the brain’s immune response to inflammatory conditions. In recent years, various CNS disorders have been related to the dysregulation of adaptive immunity, especially the process concerning Th cells and their cytokines. However, as the functions of Th cells are being discovered, it’s also found that their roles in different neuroinflammatory conditions, or even the participation of a specific Th subset in one CNS disorder may differ, and sometimes contrast. Based on those recent and contradictory evidence, the conflicting roles of Th cells in multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, epilepsy, traumatic brain injury as well as some typical mental disorders will be reviewed herein. Research progress, limitations and novel approaches concerning different neuroinflammatory conditions will also be mentioned and compared.

ZNF384: A Potential Therapeutic Target for Psoriasis and Alzheimer’s Disease Through Inflammation and Metabolism

Background

Psoriasis is an immune-related skin disease notable for its chronic inflammation of the entire system. Alzheimer’s disease (AD) is more prevalent in psoriasis than in the general population. Immune-mediated pathophysiologic processes may link these two diseases, but the mechanism is still unclear. This article aimed to explore potential molecular mechanisms in psoriasis and AD.

Methods

Gene expression profiling data of psoriasis and AD were acquired in the Gene Expression Omnibus (GEO) database. Gene Set Enrichment Analysis (GSEA) and single-sample GSEA (ssGSEA) were first applied in two datasets. Differentially expressed genes (DEGs) of two diseases were identified, and common DEGs were selected. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed to explore common biological pathways. Signature transcription factors (STFs) were identified and their diagnostic values was calculated by receiver operating characteristic (ROC) curve analysis in the exploration cohort and verified in the validation cohort. The expression levels of STFs were further investigated in the validation cohort and the GTEx Portal Database. Additionally, four kinds of interaction analysis were performed: correlation analysis among STFs, gene-gene, chemical-protein, and protein-ligand interaction analyses. In the end, we predicted the transcription factor that potentially regulates STFs.

Results

Biosynthesis and metabolic pathways were enriched in GSEA analysis. In ssGSEA analysis, most immunoreaction gene lists exhibited differential enrichment in psoriasis cases, whereas three receptor-related gene lists did in AD. The KEGG analysis of common DEGs redetermined inflammatory and metabolic pathways essential in both diseases. 5 STFs (PPARG, ZFPM2, ZNF415, HLX, and ANHX) were screened from common DEGs. The ROC analysis indicated that all STFs have diagnostic values in two diseases, especially ZFPM2. The correlation analysis, gene-gene, chemical-protein, and protein-ligand interaction analyses suggested that STFs interplay and involve inflammation and aberrant metabolism. Eventually, ZNF384 was the predicted transcription factor regulating PPARG, ZNF415, HLX, and ANHX.

Conclusions

The STFs (PPARG, ZFPM2, ZNF415, HLX, and ANHX) may increase the morbidity rate of AD in psoriasis by initiating a positive feedback loop of excessive inflammation and metabolic disorders. ZNF384 is a potential therapeutic target for psoriasis and AD by regulating PPARG, ZNF415, HLX, and ANHX.

The Role of Immunity in Alzheimer's Disease

With the increase in the aging population, age-related conditions such as dementia and Alzheimer's disease will become ever more prevalent in society. As there is no cure for dementia and extremely limited therapeutic options, researchers are examining the mechanisms that contribute to the progression of cognitive decline in hopes of developing better therapies and even an effective, long-lasting treatment for this devastating condition. This review will provide an updated perspective on the role of immunity in triggering the changes that lead to the development of dementia. It will detail the latest findings on Aβ- and tau-induced microglial activation, including the role of the inflammasome. The contribution of the adaptive immune system, specifically T cells, will be discussed. Finally, whether the innate and adaptive immune system can be modulated to protect against dementia will be examined, along with an assessment of the prospective candidates for these that are currently in clinical trials.

The role of Th17 cells/IL-17A in AD, PD, ALS and the strategic therapy targeting on IL-17A

Neurodegenerative diseases are a group of disorders characterized by progressive loss of certain populations of neurons, which eventually lead to dysfunction. These diseases include Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). Immune pathway dysregulation is one of the common features of neurodegeneration. Recently, there is growing interest in the specific role of T helper Th 17 cells and Interleukin-17A (IL-17A), the most important cytokine of Th 17 cells, in the pathogenesis of the central nervous system (CNS) of neurodegenerative diseases. In the present study, we summarized current knowledge about the function of Th17/IL-17A, the physiology of Th17/IL-17A in diseases, and the contribution of Th17/IL-17A in AD, PD, and ALS. We also update the findings on IL-17A-targeting drugs as potentially immunomodulatory therapeutic agents for neurodegenerative diseases. Although the specific mechanism of Th17/IL-17A in this group of diseases is still controversial, uncovering the molecular pathways of Th17/IL-17A in neurodegeneration allows the identification of suitable targets to modulate these cellular processes. Therapeutics targeting IL-17A might represent potentially novel anti-neurodegeneration drugs.

Psoriasis and Systemic Inflammatory Disorders

Psoriasis is a representative inflammatory skin disease occupied by large surface involvement. As inflammatory cells and cytokines can systemically circulate in various organs, it has been speculated that psoriatic skin inflammation influences the systemic dysfunction of various organs. Recent updates of clinical studies and experimental studies showed the important interaction of psoriasis to systemic inflammatory diseases. Furthermore, the importance of systemic therapy in severe psoriasis is also highlighted to prevent the development of systemic inflammatory diseases. In this review, we introduced representative systemic inflammatory diseases associated with psoriasis and the detailed molecular mechanisms.

Polysaccharide from Ganoderma lucidum alleviates cognitive impairment in a mouse model of chronic cerebral hypoperfusion by regulating CD4+CD25+Foxp3+ regulatory T cells

Ganoderma lucidum (G. lucidum) is a kind of edible and medicinal mushroom. G. lucidum polysaccharide-1 (GLP-1) is one of the polysaccharides purified from crude GLP. Chronic cerebral hypoperfusion (CCH) as the common pathological basis of various forms of dementia is an important cause of cognitive impairment. In this study, a step-down test was used to evaluate the cognitive ability of CCH mice. Flow cytometry was used to detect the proportion of CD4⁺CD25⁺Foxp3⁺ regulatory T (Foxp3⁺Treg) cells. ELISA analysis and western blot analysis were used to detect the transforming growth factor-β1 (TGF-β1) and Interleukin-10 (IL-10) levels that Foxp3⁺Treg cells secreted. Metabolomic analysis based on gas chromatography-mass spectrometry (GC-MS) was used to evaluate the effect of GLP-1 on dysfunctional metabolism caused by inflammation. Results indicate that GLP-1 exhibited an alleviating cognitive impairment effect on CCH mice. The mechanism was related to GLP-1 by increasing Foxp3⁺Treg cell levels to increase levels of IL-10 and TGF-β1 and regulate abnormal energy metabolism. These findings could provide preliminary results to exploit G. lucidum as a health care product or functional food for the adjuvant therapy of cognitive impairment of CCH.

Non-immune functions of inflammatory cytokines targeted by anti-psoriatic biologics: a review

PURPOSE

Psoriasis is an inflammatory disease characterized by skin thickening with silvery white desquamation due to dysregulated inflammatory pathways and elevated levels of inflammatory cytokines. Biologic agents targeting these inflammatory cytokines have brought about significant improvement in clearing psoriatic lesions in patients with moderate-to-severe psoriasis. Moreover, biologics exert both beneficial and detrimental effects on comorbidities in psoriasis, which include increased risk of cardiovascular events, metabolic syndrome, among other conditions. However, non-immune functions of cytokines targeted by biologics, and, hence, the potential risks and benefits of biologics for psoriasis to different organs/systems and comorbidities, have not been well elucidated.

RESULTS

This review summarizes current understanding of the pathogenesis of psoriasis-related comorbidities and emerging discoveries of roles of cytokines targeted in psoriasis treatment, including tumor necrosis factor α and interleukins 12, 23, and 17, aiming to complete the safety profile of each biologics and provide therapeutic implications on psoriasis-related comorbidities, and on diseases involving other organs or systems.

Neuroimmune contributions to Alzheimer's disease: a focus on human data

The past decade has seen the convergence of a series of new insights that arose from genetic and systems analyses of Alzheimer's disease (AD) with a wealth of epidemiological data from a variety of fields; this resulted in renewed interest in immune responses as important, potentially causal components of AD. Here, we focus primarily on a review of human data which has recently yielded a set of robust, reproducible results that exist in a much larger universe of conflicting reports stemming from small studies with important limitations in their study design. Thus, we are at an important crossroads in efforts to first understand at which step of the long, multiphasic course of AD a given immune response may play a causal role and then modulate this response to slow or block the pathophysiology of AD. We have a wealth of new experimental tools, analysis methods, and capacity to sample human participants at large scale longitudinally; these resources, when coupled to a foundation of reproducible results and novel study designs, will enable us to monitor human immune function in the CNS at the level of complexity that is required while simultaneously capturing the state of the peripheral immune system. This integration of peripheral and central perturbations in immune responses results in pathologic responses in the central nervous system parenchyma where specialized cellular microenvironments composed of multiple cell subtypes respond to these immune perturbations as well as to environmental exposures, comorbidities and the impact of the advancing life course. Here, we offer an overview that seeks to illustrate the large number of interconnecting factors that ultimately yield the neuroimmune component of AD.

T cells in the brain inflammation

The immune system is deeply involved in autoimmune diseases of the central nervous system (CNS), such as multiple sclerosis, N-methyl-d-aspartate (NMDA) receptor encephalitis, and narcolepsy. Additionally, the immune system is involved in various brain diseases including cerebral infarction and neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In particular, reports related to T cells are increasing. T cells may also play important roles in brain deterioration and dementia that occur with aging. Our understanding of the role of immune cells in the context of the brain has been greatly improved by the use of acute ischemic brain injury models. Additionally, similar neural damage and repair events are shown to occur in more chronic brain neurodegenerative brain diseases. In this review, we focus on the role of T cells, including CD4⁺ T cells, CD8⁺ T cells and regulatory T cells (Tregs) in cerebral infarction and neurodegenerative diseases.