Dysregulation of C-X-C motif ligand 10 during aging and association with cognitive performance

Involvement of CXCL10 rs4256246, CXCR4 rs2228014, CCR2 rs1799864 and CXCL16 rs2277680 in the Predisposition to Schizophrenia

Chemokine ligands and their receptors have acquired less attention than pro- and anti-inflammatory cytokines in schizophrenia (SCZ). Thus, we aimed to examine the impact of functional polymorphisms of the chemokine genes CXCL10, CXCL16, CXCR4, and CCR2 in the development of SCZ. Using PCR-RFLP, we analyzed the selected polymorphisms in a Tunisian cohort composed of 200 patients with SCZ and 200 healthy controls. Our preliminary data suggest that the minor allele A of CXCL10 rs4256246 is significantly associated with likelihood of SCZ (PAdjusted = 0.00002) and more precisely to paranoid patients with late-onset SCZ (PAdjusted = 0.0007). However, the mutated allele T of CXCR4 rs2228014 showed a significant protective impact against SCZ (PAdjusted = 0.000007) and especially to male sex (PAdjusted = 0.000003). This effect persists among the undifferentiated patients with early-onset SCZ (PAdjusted = 0.002). Following the stratified analyses, CCR2 rs1799864 and CXCL16 rs2277680 were significantly correlated with the clinical symptoms among disorganized patients. As regards haplotype analysis, we noted that GATG haplotype was associated with protection against SCZ (PAdjusted = 0.0087) but the AGCG haplotype was correlated with susceptibility to this disease (PAdjusted = 0.014). Our preliminary results suggested that CXCL10 rs4256246 enhanced susceptibility to SCZ, while CXCR4 rs2228014 seemed to be protective factor. Furthermore, we identified a substantial correlation between CCR2 rs1799864 and CXCL16 rs2277680 with the clinical signs of the disorder. To validate these results and clarify the functional significance of the targeted polymorphisms in SCZ, more independent research is needed.

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.

Increased levels of GM-CSF and CXCL10 and low CD8+ memory stem T Cell count are markers of immunosenescence and severe COVID-19 in older people

BACKGROUND

Ageing leads to altered immune responses, resulting in higher susceptibility to certain infections in the elderly. Immune ageing is a heterogeneous process also associated with inflammaging, a low-grade chronic inflammation. Altered cytotoxic T cell responses and cytokine storm have previously been described in severe COVID-19 cases, however the parameters responsible for such immune response failures are not well known. The aim of our study was to characterize CD8+ T cells and cytokines associated with ageing, in a cohort of patients aged over 70 years stratified by COVID-19 severity.

RESULTS

One hundred and four patients were included in the study. We found that, in older people, COVID-19 severity was associated with (i) higher level of GM-CSF, CXCL10 (IP-10), VEGF, IL-1β, CCL2 (MCP-1) and the neutrophil to lymphocyte ratio (NLR), (ii) increased terminally differentiated CD8+T cells, and (ii) decreased early precursors CD8+ T stem cell-like memory cells (TSCM) and CD27+CD28+. The cytokines mentioned above were found at higher concentrations in the COVID-19+ older cohort compared to a younger cohort in which they were not associated with disease severity.

CONCLUSIONS

Our results highlight the particular importance of the myeloid lineage in COVID-19 severity among older people. As GM-CSF and CXCL10 were not associated with COVID-19 severity in younger patients, they may represent disease severity specific markers of ageing and should be considered in older people care.

Circulating biomarkers of inflammaging and Alzheimer's disease to track age-related trajectories of dementia: Can we develop a clinically relevant composite combination?

Alzheimer's disease (AD) is a rapidly growing global concern due to a consistent rise of the prevalence of dementia which is mainly caused by the aging population worldwide. An early diagnosis of AD remains important as interventions are plausibly more effective when started at the earliest stages. Recent developments in clinical research have focused on the use of blood-based biomarkers for improve diagnosis/prognosis of neurodegenerative diseases, particularly AD. Unlike invasive cerebrospinal fluid tests, circulating biomarkers are less invasive and will become increasingly cheaper and simple to use in larger number of patients with mild symptoms or at risk of dementia. In addition to AD-specific markers, there is growing interest in biomarkers of inflammaging/neuro-inflammaging, an age-related chronic low-grade inflammatory condition increasingly recognized as one of the main risk factor for almost all age-related diseases, including AD. Several inflammatory markers have been associated with cognitive performance and AD development and progression. The presence of senescent cells, a key driver of inflammaging, has also been linked to AD pathogenesis, and senolytic therapy is emerging as a potential treatment strategy. Here, we describe blood-based biomarkers clinically relevant for AD diagnosis/prognosis and biomarkers of inflammaging associated with AD. Through a systematic review approach, we propose that a combination of circulating neurodegeneration and inflammatory biomarkers may contribute to improving early diagnosis and prognosis, as well as providing valuable insights into the trajectory of cognitive decline and dementia in the aging population.

Blood-based biomarkers for Alzheimer's disease: Current state and future use in a transformed global healthcare landscape

Timely detection of the pathophysiological changes and cognitive impairment caused by Alzheimer's disease (AD) is increasingly pressing because of the advent of biomarker-guided targeted therapies that may be most effective when provided early in the disease. Currently, diagnosis and management of early AD are largely guided by clinical symptoms. FDA-approved neuroimaging and cerebrospinal fluid biomarkers can aid detection and diagnosis, but the clinical implementation of these testing modalities is limited because of availability, cost, and perceived invasiveness. Blood-based biomarkers (BBBMs) may enable earlier and faster diagnoses as well as aid in risk assessment, early detection, prognosis, and management. Herein, we review data on BBBMs that are closest to clinical implementation, particularly those based on measures of amyloid-β peptides and phosphorylated tau species. We discuss key parameters and considerations for the development and potential deployment of these BBBMs under different contexts of use and highlight challenges at the methodological, clinical, and regulatory levels.

Small immunological clocks identified by deep learning and gradient boosting

Background

The aging process affects all systems of the human body, and the observed increase in inflammatory components affecting the immune system in old age can lead to the development of age-associated diseases and systemic inflammation.

Results

We propose a small clock model SImAge based on a limited number of immunological biomarkers. To regress the chronological age from cytokine data, we first use a baseline Elastic Net model, gradient-boosted decision trees models, and several deep neural network architectures. For the full dataset of 46 immunological parameters, DANet, SAINT, FT-Transformer and TabNet models showed the best results for the test dataset. Dimensionality reduction of these models with SHAP values revealed the 10 most age-associated immunological parameters, taken to construct the SImAge small immunological clock. The best result of the SImAge model shown by the FT-Transformer deep neural network model has mean absolute error of 6.94 years and Pearson ρ = 0.939 on the independent test dataset. Explainable artificial intelligence methods allow for explaining the model solution for each individual participant.

Conclusions

We developed an approach to construct a model of immunological age based on just 10 immunological parameters, coined SImAge, for which the FT-Transformer deep neural network model had proved to be the best choice. The model shows competitive results compared to the published studies on immunological profiles, and takes a smaller number of features as an input. Neural network architectures outperformed gradient-boosted decision trees, and can be recommended in the further analysis of immunological profiles.

Association between Periodontal Disease and Cognitive Impairment in Adults

INTRODUCTION

Periodontitis is a severe oral infection that can contribute to systemic inflammation. A large body of evidence suggests a role for systemic inflammation in the initiation of neurodegenerative disease. This systematic review synthesized data from observational studies to investigate the association between periodontitis and neuroinflammation in adults.

METHODS AND MATERIALS

A systematic literature search of PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) was performed for studies published from the date of inception up to September 2021. Search terms for the exposure "oral disease" and outcome "dementia", "neuroinflammation" and "cognitive decline" were used. Study selection and data extraction were independently undertaken by two reviewers. The final eligible articles were included only if the exposure is periodontitis and the outcome is cognitive impairment or dementia or a topic related to this condition, and if the study was conducted in an adult population. The quality and risk of bias were assessed by Newcastle Ottawa Scale (NOS). Qualitative synthesis was used to narratively synthesize the results. Six cohort studies, three cross-sectional studies, and two case-control studies met the inclusion criteria. These eleven studies were only narratively synthesized. Meta-analysis was not performed due to the methodological heterogeneity of the studies.

RESULTS

The results of included studies show that chronic periodontitis patients with at least eight years of exposure are at higher risk of developing cognitive decline and dementia. Oral health measures such as gingival inflammation, attachment loss, probing depth, bleeding on probing, and alveolar bone loss are associated with cognitive impairment. The reduction of epidermal growth factor (EGF), interleukin 8 (IL-8), interferon γ-induced protein 10 (IP-10), and monocyte chemoattractant protein-1 (MCP-1) in addition to over expression of interleukin 1-β (IL-1β) are significant in patients suffering from cognitive decline with pre-existing severe periodontitis.

CONCLUSIONS

All the included studies show evidence of an association between periodontitis and cognitive impairment or dementia and Alzheimer's disease pathology. Nonetheless, the mechanisms responsible for the association between periodontitis and dementia are still unclear and warrant further investigation.

Genome-wide identification of murine interferon genes in microglial-mediated neuroinflammation in Alzheimer's disease

Interferons play a major role in microglial-mediated neuroinflammation in Alzheimer's disease (AD). We investigated the interferon transcriptome (AD versus non-AD) using N9 and murine microglia. We identified 64 interferon-related differentially expressed genes (DEG) in LPS-stimulated N9 microglia versus control cells, 26 DEG in microglia from 5XFAD versus wild-type mice, with 13 DEG common to both datasets. Network analyses identified potential key mediators (Cxcl10, Ifit3) of the interferon response in AD. Gene-drug interaction analysis identified therapeutics targeting interferon-related genes. These data characterize the microglial interferon response in AD, providing new targets and therapeutics directed towards interferon-related neuroinflammation in AD.

Blood-brain barrier dysfunction promotes astrocyte senescence through albumin-induced TGFβ signaling activation

Blood-brain barrier dysfunction (BBBD) and accumulation of senescent astrocytes occur during brain aging and contribute to neuroinflammation and disease. Here, we explored the relationship between these two age-related events, hypothesizing that chronic hippocampal exposure to the blood-borne protein serum albumin could induce stress-induced premature senescence (SIPS) in astrocytes via transforming growth factor beta 1 (TGFβ) signaling. We found that 1 week of albumin exposure significantly increased TGFβ signaling and senescence marker expression in cultured rat hippocampal astrocytes. These changes were preventable by pharmacological inhibition of the type I TGFβ receptor (TGFβR) ALK5. To study these effects in vivo, we utilized an animal model of BBBD in which albumin was continuously infused into the lateral ventricles of adult mice. Consistent with our in vitro results, 1 week of albumin infusion significantly increased TGFβ signaling activation and the burden of senescent astrocytes in hippocampal tissue. Pharmacological inhibition of ALK5 TGFβR or conditional genetic knockdown of astrocytic TGFβR prior to albumin infusion was sufficient to prevent albumin-induced astrocyte senescence. Together, these results establish a link between TGFβ signaling activation and astrocyte senescence and suggest that prolonged exposure to serum albumin due to BBBD can trigger these phenotypic changes.

Association between Perceived Health-Related Quality of Life and Depression with Frailty in the FRASNET Study

Frailty is a major challenge facing the aging world. The phenotype of the frail subject is still far from being satisfactorily defined. We report data on mood, cognition, and quality of life (QoL) in relation to anamnestic factors, health, and socio-economic status in the FRASNET geriatric population (1204 subjects in stable health conditions), which is an observational cohort study that includes fairly balanced groups of Italian frail (421, 35%), pre-frail (449, 37.3%) and robust (334, 27.7%) subjects. A conditional inference tree analysis revealed a substantial influence of psychological variables on frailty. The physical indicator of QoL (Short Form Survey-36-Physical Component Summary, SF-36-PCS) was the predominant variable in the full model (threshold at 39.9, p < 0.001): higher frailty was found in subjects with a caregiver and lower SF-36-PCS. Frailty was also associated with the mental indicator of QoL (Short Form Survey-36-Mental Component Summary, SF-36-MCS), depression (Geriatric Depression Scale, GDS-15), leisure activities, and level of education. In support of the prominent role of inflammation in aging and mental illness, the SF-36-PCS score was correlated with the blood concentration of C-X-C motif chemokine ligand 10 (CXCL10) (r Pearson -0.355, p = 0.015), a critical signal in cell senescence and inflammaging, while the rs7567647 variant in FN1 gene encoding a glycoprotein in the extracellular matrix was significantly associated with frailty in a multivariable model (p = 0.0006). The perception of health-related QoL and subclinical depression contribute to frailty. Their assessment could improve the identification of older patients at increased risk of adverse outcomes.

Neurons burdened by DNA double-strand breaks incite microglia activation through antiviral-like signaling in neurodegeneration

DNA double-strand breaks (DSBs) are linked to neurodegeneration and senescence. However, it is not clear how DSB-bearing neurons influence neuroinflammation associated with neurodegeneration. Here, we characterize DSB-bearing neurons from the CK-p25 mouse model of neurodegeneration using single-nucleus, bulk, and spatial transcriptomic techniques. DSB-bearing neurons enter a late-stage DNA damage response marked by nuclear factor κB (NFκB)-activated senescent and antiviral immune pathways. In humans, Alzheimer's disease pathology is closely associated with immune activation in excitatory neurons. Spatial transcriptomics reveal that regions of CK-p25 brain tissue dense with DSB-bearing neurons harbor signatures of inflammatory microglia, which is ameliorated by NFκB knockdown in neurons. Inhibition of NFκB in DSB-bearing neurons also reduces microglia activation in organotypic mouse brain slice culture. In conclusion, DSBs activate immune pathways in neurons, which in turn adopt a senescence-associated secretory phenotype to elicit microglia activation. These findings highlight a previously unidentified role for neurons in the mechanism of disease-associated neuroinflammation.

Functional and Phenotypic Diversity of Microglia: Implication for Microglia-Based Therapies for Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disease and is closely associated with the accumulation of β-amyloid (Aβ) and neurofibrillary tangles (NFTs). Apart from Aβ and NFT pathologies, AD patients also exhibit a widespread microglial activation in various brain regions with elevated production of pro-inflammatory cytokines, a phenomenon known as neuroinflammation. In healthy central nervous system, microglia adopt ramified, “surveying” phenotype with compact cell bodies and elongated processes. In AD, the presence of pathogenic proteins such as extracellular Aβ plaques and hyperphosphorylated tau, induce the transformation of ramified microglia into amoeboid microglia. Ameboid microglia are highly phagocytic immune cells and actively secrete a cascade of pro-inflammatory cytokines and chemokines. However, the phagocytic ability of microglia gradually declines with age, and thus the clearance of pathogenic proteins becomes highly ineffective, leading to the accumulation of Aβ plaques and hyperphosphorylated tau in the aging brain. The accumulation of pathogenic proteins further augments the neuroinflammatory responses and sustains the activation of microglia. The excessive production of pro-inflammatory cytokines induces a massive loss of functional synapses and neurons, further worsening the disease condition of AD. More recently, the identification of a subset of microglia by transcriptomic studies, namely disease-associated microglia (DAM), the progressive transition from homeostatic microglia to DAM is TREM2-dependent and the homeostatic microglia gradually acquire the state of DAM during the disease progression of AD. Recent in-depth transcriptomic analysis identifies ApoE and Trem2 from microglia as the major risk factors for AD pathogenesis. In this review, we summarize current understandings of the functional roles of age-dependent microglial activation and neuroinflammation in the pathogenesis of AD. To this end, the exponential growth in transcriptomic data provides a solid foundation for in silico drug screening and gains further insight into the development of microglia-based therapeutic interventions for AD.

Interconnections between Inflammageing and Immunosenescence during Ageing

Acute inflammation is a physiological response to injury or infection, with a cascade of steps that ultimately lead to the recruitment of immune cells to clear invading pathogens and heal wounds. However, chronic inflammation arising from the continued presence of the initial trigger, or the dysfunction of signalling and/or effector pathways, is harmful to health. While successful ageing in older adults, including centenarians, is associated with low levels of inflammation, elevated inflammation increases the risk of poor health and death. Hence inflammation has been described as one of seven pillars of ageing. Age-associated sterile, chronic, and low-grade inflammation is commonly termed inflammageing-it is not simply a consequence of increasing chronological age, but is also a marker of biological ageing, multimorbidity, and mortality risk. While inflammageing was initially thought to be caused by "continuous antigenic load and stress", reports from the last two decades describe a much more complex phenomenon also involving cellular senescence and the ageing of the immune system. In this review, we explore some of the main sources and consequences of inflammageing in the context of immunosenescence and highlight potential interventions. In particular, we assess the contribution of cellular senescence to age-associated inflammation, identify patterns of pro- and anti-inflammatory markers characteristic of inflammageing, describe alterations in the ageing immune system that lead to elevated inflammation, and finally assess the ways that diet, exercise, and pharmacological interventions can reduce inflammageing and thus, improve later life health.

Cellular and molecular influencers of neuroinflammation in Alzheimer's disease: Recent concepts & roles

Alzheimer's disease (AD), an extremely common neurodegenerative disorder of the older generation, is one of the leading causes of death globally. Besides the conventional hallmarks i.e. Amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs), neuroinflammation also serves as a major contributing factor in the pathogenesis of AD. There are mounting evidences to support the fundamental role of cellular (microglia, astrocytes, mast cells, and T-cells) and molecular (cytokines, chemokines, caspases, and complement proteins) influencers of neuroinflammation in producing/promoting neurodegeneration and dementia in AD. Genome-wide association studies (GWAS) have revealed the involvement of various single nucleotide polymorphisms (SNPs) of genes related to neuroinflammation with the risk of developing AD. Modulating the release of the neuroinflammatory molecules and targeting their relevant mechanisms may have beneficial effects on the onset, progress and severity of the disease. Here, we review the distinct role of various mediators and modulators of neuroinflammation that impact the pathogenesis and progression of AD as well as incite further research efforts for the treatment of AD through a neuroinflammatory approach.

Sex differences and similarities in the neuroimmune response to central administration of poly I:C

BACKGROUND

The neuroimmune system is required for normal neural processes, including modulation of cognition, emotion, and adaptive behaviors. Aberrant neuroimmune activation is associated with dysregulation of memory and emotion, though the precise mechanisms at play are complex and highly context dependent. Sex differences in neuroimmune activation and function further complicate our understanding of its roles in cognitive and affective regulation.

METHODS

Here, we characterized the physiological sickness and inflammatory response of the hippocampus following intracerebroventricular (ICV) administration of a synthetic viral mimic, polyinosinic:polycytidylic acid (poly I:C), in both male and female C57Bl/6N mice.

RESULTS

We observed that poly I:C induced weight loss, fever, and elevations of cytokine and chemokines in the hippocampus of both sexes. Specifically, we found transient increases in gene expression and protein levels of IL-1α, IL-1β, IL-4, IL-6, TNFα, CCL2, and CXCL10, where males showed a greater magnitude of response compared with females. Only males showed increased IFNα and IFNγ in response to poly I:C, whereas both males and females exhibited elevations of IFNβ, demonstrating a specific sex difference in the anti-viral response in the hippocampus.

CONCLUSION

Our data suggest that type I interferons are one potential node mediating sex-specific cytokine responses and neuroimmune effects on cognition. Together, these findings highlight the importance of using both males and females and analyzing a broad set of inflammatory markers in order to identify the precise, sex-specific roles for neuroimmune dysregulation in neurological diseases and disorders.

Identifying the Main Functional Pathways Associated with Cognitive Resilience to Alzheimer's Disease

Understanding the mechanisms involved in cognitive resilience in Alzheimer’s disease (AD) represents a promising strategy to identify novel treatments for dementia in AD. Previous findings from our group revealed that the study of aged-Tg2576 cognitive resilient individuals is a suitable tool for this purpose. In the present study, we performed a transcriptomic analysis using the prefrontal cortex of demented and resilient Tg2576 transgenic AD mice. We have been able to hypothesize that pathways involved in inflammation, amyloid degradation, memory function, and neurotransmission may be playing a role on cognitive resilience in AD. Intriguingly, the results obtained in this study are suggestive of a reduction of the influx of peripheral immune cells into the brain on cognitive resilient subjects. Indeed, CD4 mRNA expression is significantly reduced on Tg2576 mice with cognitive resilience. For further validation of this result, we analyzed CD4 expression in human AD samples, including temporal cortex and peripheral blood mononuclear cells (PBMC). Interestingly, we have found a negative correlation between CD4 mRNA levels in the periphery and the score in the Mini-Mental State Exam of AD patients. These findings highlight the importance of understanding the role of the immune system on the development of neurodegenerative diseases and points out to the infiltration of CD4⁺ cells in the brain as a key player of cognitive dysfunction in AD.

Circulating inflammatory markers impact cognitive functions in bipolar depression

BACKGROUND

Cognitive impairment is a core feature of bipolar disorder, with a prevalence of about 64.4% during episodes and 57.1% in euthymia. Recent evidences suggest that cognitive deficits in BD may follow immune dysfunction and elevated levels of inflammatory cytokines have been reported during periods of depression, mania and euthymia, suggesting the presence of a chronic, low-grade inflammatory state. The aim of the study is to investigate if immune/inflammatory markers and especially chemokines associate to cognitive performances.

METHODS

Seventy-six consecutively admitted inpatients with a depressive episode in course of bipolar disorder performed a neuropsychological evaluation with the Brief Assessment of Cognition in Schizophrenia and plasma blood levels of cytokines, chemokines and growth factors were analyzed with Luminex technology.

RESULTS

Higher levels of IL-1β, IL-6, CCL2, CCL4, CCL5, CXCL10, and bFGF are associated with the likelihood of having a poor cognitive performance.

LIMITATIONS

Limitation include the lack of a group of healthy controls and the lack of information regarding previous psychopharmacological treatments, alcohol and tobacco use.

CONCLUSIONS

Our results confirm the importance of chemokines in bipolar disorder and suggest that inflammatory markers suggestive of a low-grade inflammatory state could contribute to the neurocognitive deficits observed in depressed patients.

Superior Frontal Gyrus TOMM40-APOE Locus DNA Methylation in Alzheimer's Disease

Background:

The APOE ɛ4 allele is the strongest known genetic risk factor for sporadic Alzheimer’s disease (AD). The neighboring TOMM40 gene has also been implicated in AD due to its close proximity to APOE.

Objective:

Here we tested whether methylation of the TOMM40-APOE locus may influence ApoE protein levels and AD pathology.

Methods:

DNA methylation levels across the TOMM40-APOE locus and ApoE levels were measured in superior frontal gyrus tissues of 62 human brains genotyped for APOE and scored for AD neuropathology.

Results:

Methylation levels within the TOMM40 CpG island in the promoter or APOE CpG island in Exon 4 did not differ between APOE ɛ4 carriers versus non-carriers. However, APOE ɛ4 carriers had significantly higher methylation the APOE promoter compared with non-carriers. Although DNA methylation at TOMM40, APOE promoter region, or APOE did not differ between AD pathological groups, there was a negative association between TOMM40 methylation and CERAD scores. ApoE protein concentrations did not significantly different between APOE ɛ4 carriers and non-carriers, or between AD pathological groups. Finally, there was no correlation between ApoE protein concentrations and DNA methylation levels.

Conclusion:

APOE gene methylation may not be affected by genotype, relate to AD pathology or ApoE protein levels in the superior frontal gyrus, though, DNA methylation at the ApoE promoter differed between genotype. DNA methylation at TOMM40 associated with amyloid-β plaques and longitudinal fluid intelligence. In sum, these results suggest a complicated regulation of the TOMM40-APOE locus in the brain in controlling ApoE protein levels and AD neuropathology.

Profiling Microglia From Alzheimer's Disease Donors and Non-demented Elderly in Acute Human Postmortem Cortical Tissue

Microglia are the tissue-resident macrophages of the central nervous system (CNS). Recent studies based on bulk and single-cell RNA sequencing in mice indicate high relevance of microglia with respect to risk genes and neuro-inflammation in Alzheimer's disease (AD). Here, we investigated microglia transcriptomes at bulk and single-cell levels in non-demented elderly and AD donors using acute human postmortem cortical brain samples. We identified seven human microglial subpopulations with heterogeneity in gene expression. Notably, gene expression profiles and subcluster composition of microglia did not differ between AD donors and non-demented elderly in bulk RNA sequencing nor in single-cell sequencing.

Acute Systemic Inflammatory Response Alters Transcription Profile of Genes Related to Immune Response and Ca2+ Homeostasis in Hippocampus; Relevance to Neurodegenerative Disorders

Acute systemic inflammatory response (SIR) triggers an alteration in the transcription of brain genes related to neuroinflammation, oxidative stress and cells death. These changes are also characteristic for Alzheimer’s disease (AD) neuropathology. Our aim was to evaluate gene expression patterns in the mouse hippocampus (MH) by using microarray technology 12 and 96 h after SIR evoked by lipopolysaccharide (LPS). The results were compared with microarray analysis of human postmortem hippocampal AD tissues. It was found that 12 h after LPS administration the expression of 231 genes in MH was significantly altered (FC > 2.0); however, after 96 h only the S100a8 gene encoding calgranulin A was activated (FC = 2.9). Gene ontology enrichment analysis demonstrated the alteration of gene expression related mostly to the immune-response including the gene Lcn2 for Lipocalin 2 (FC = 237.8), involved in glia neurotoxicity. The expression of genes coding proteins involved in epigenetic regulation, histone deacetylases (Hdac4,5,8,9,11) and bromo- and extraterminal domain protein Brd3 were downregulated; however, Brd2 was found to be upregulated. Remarkably, the significant increase in expression of Lcn2, S100a8, S100a9 and also Saa3 and Ch25h, was found in AD brains suggesting that early changes of immune-response genes evoked by mild SIR could be crucial in AD pathogenesis.

The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease

The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.

CD8+ T-cells infiltrate Alzheimer's disease brains and regulate neuronal- and synapse-related gene expression in APP-PS1 transgenic mice

Neuroinflammation is a major contributor to disease progression in Alzheimer's disease (AD) and is characterized by the activity of brain resident glial cells, in particular microglia cells. However, there is increasing evidence that peripheral immune cells infiltrate the brain at certain stages of AD progression and shape disease pathology. We recently identified CD8⁺ T-cells in the brain parenchyma of APP-PS1 transgenic mice being tightly associated with microglia as well as with neuronal structures. The functional role of CD8⁺ T-cells in the AD brain is however completely unexplored. Here, we demonstrate increased numbers of intra-parenchymal CD8⁺ T-cells in human AD post-mortem hippocampus, which was replicated in APP-PS1 mice. Also, aged WT mice show a remarkable infiltration of CD8⁺ T-cells, which was more pronounced and had an earlier onset in APP-PS1 mice. To address their functional relevance in AD, we successfully ablated the pool of CD8⁺ T-cells in the blood, spleen and brain from 12 months-old APP-PS1 and WT mice for a total of 4 weeks using an anti-CD8 antibody treatment. While the treatment at this time of disease stage did neither affect the cognitive outcome nor plaque pathology, RNAseq analysis of the hippocampal transcriptome from APP-PS1 mice lacking CD8⁺ T-cells revealed highly altered neuronal- and synapse-related gene expression including an up-regulation for neuronal immediate early genes (IEGs) such as the Activity Regulated Cytoskeleton Associated Protein (Arc) and the Neuronal PAS Domain Protein 4 (Npas4). Gene ontology enrichment analysis illustrated that the biological processes "regulation of neuronal synaptic plasticity" and the cellular components "postsynapses" were over-represented upon CD8⁺ T-cell ablation. Additionally, Kegg pathway analysis showed up-regulated pathways for "calcium signaling", "long-term potentiation", "glutamatergic synapse" and "axon guidance". Therefore, we conclude that CD8⁺ T-cells infiltrate the aged and AD brain and that brain CD8⁺ T-cells might directly contribute to neuronal dysfunction in modulating synaptic plasticity. Further analysis will be essential to uncover the exact mechanism of how CD8⁺ T-cells modulate the neuronal landscape and thereby contribute to AD pathology.

Cognition Is Associated With Peripheral Immune Molecules in Healthy Older Adults: A Cross-Sectional Study

Background

Cognition in the elderly is heterogeneous. Senescence of the immune system is increasingly considered as a potential player in cognitive performance. We explored here the interplay between cognitive performance and peripheral immune molecules in healthy older individuals.

Methods

A cross-sectional study of clinically well characterized senior healthy individuals (120; 51-87 years old) previously clustered as "Good" and "Poor" performers based on established tests that evaluate memory and executive function. A plasma concentration of 30 immune molecules was assessed by multiplex analysis and correlated with parameters of cognitive performance.

Results

Participants with worse cognitive performance ("Poor") exhibited increased concentrations of IL-1β, IL-8, IL-13, and tumor necrosis factor (TNF) when compared to individuals with a better cognitive performance ("Good"). The cognitive dimensions memory and executive function, when considered separately, displayed a negative association with several immune molecules (IL-1β, IL-1RA, IL-6, IL-13, IP-10, and TNF with memory and only IL-1β with executive function), even controlling for age, sex, years of formal education, mood, and use of anti-inflammatory drugs. Regression analysis showed that several of these molecules (IL-1β, IL-6, IL-8, and IL-13) contribute to predicting whether an individual belongs to the "Good" or "Poor" cognitive performance group.

Conclusion

These results strengthen the hypothesis that increased concentrations of peripheral immune molecules, like IL-1β, are associated with worse cognitive performance in senior healthy individuals. It further highlights that some poorly studied immune molecules should be considered in the context of cognitive aging, such as IL-13, here revealed as a new player in such interaction.

Dysregulation of BDNF in Prefrontal Cortex in Alzheimer's Disease

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is essential for neurogenesis and has been implicated in Alzheimer's disease (AD). However, few studies have investigated together the epigenetic, transcriptional, and translational regulation of this peptide in the brain in relation to AD.

OBJECTIVE

To investigate mechanisms underlying how BDNF is possibly dysregulated in the brain in relation to aging and AD neuropathology.

METHODS

Prefrontal cortex tissues were acquired from the Manchester Brain Bank (N = 67). BDNF exon I, and exon IV-containing transcripts and total long 3' transcript gene expression were determined by quantitative PCR and bisulfite pyrosequencing was used to quantify DNA methylation within promoters I and IV. Protein concentrations were quantified via ELISA.

RESULTS

BDNF exon IV and total long 3' isoform gene expression levels negatively associated with donor's age at death (IV: r = -0.291, p = 0.020; total: r = -0.354, p = 0.004). Expression of BDNF exon I- containing isoform was significantly higher in Met-carriers of the rs6265 variant, compared to Val-homozygotes, when accounting for donor ages (F = 6.455, p = 0.014). BDNF total long 3' transcript expression was significantly lower in those with early AD neuropathology, compared to those without any neuropathology (p = 0.021). There were no associations between BDNF promoter I and IV methylation or protein levels with ages, rs6265 genotype or AD neuropathology status.

CONCLUSION

Prefrontal cortex BDNF gene expression is associated with aging, rs6265 carrier status, and AD neuropathology in a variant-specific manner that seems to be independent of DNA methylation influences.

Regulation of interleukin 6 by a polymorphic CpG within the frontal cortex in Alzheimer's disease

The cytokine interleukin 6 (IL-6) has been linked to the pathogenesis of Alzheimer's disease (AD). This is the first study to investigate the genetic and epigenetic interactions in the control of IL-6 in human brain and its relation to AD neuropathology in prefrontal cortex tissues from AD and controls genotyped for the SNP -174 C/G rs1800795, a polymorphic CpG in which the G allele creates a CpG site. Within CC homozygotes there were significantly higher brain levels of IL-6 protein compared to G allele carriers. The C allele that resulted in an absence of methylation at a CpG was also associated with significant changes in methylation at neighboring CpGs. Furthermore, there were significant differences in methylation between CC and CG/GG at CpG sites in the AD and control groups. That DNA methylation was altered in the brains by the presence of rs1800795, which further correlated with protein levels suggests the presence of a polymorphic CpG and genetic-epigenetic interactions in the regulation of IL-6 in the prefrontal cortex within AD brains.

The Influence of Physical Activity and Epigenomics On Cognitive Function and Brain Health in Breast Cancer

The risk of breast cancer increases with age, with the majority of women diagnosed with breast cancer being postmenopausal. It has been estimated that 25-75% of women with breast cancer experience changes in cognitive function (CF) related to disease and treatment, which compromises psychological well-being, decision making, ability to perform daily activities, and adherence to cancer therapy. Unfortunately, the mechanisms that underlie neurocognitive changes in women with breast cancer remain poorly understood, which in turn limits the development of effective treatments and prevention strategies. Exercise has great potential as a non-pharmaceutical intervention to mitigate the decline in CF in women with breast cancer. Evidence suggests that DNA methylation, an epigenetic mechanism for gene regulation, impacts CF and brain health (BH), that exercise influences DNA methylation, and that exercise impacts CF and BH. Although investigating DNA methylation has the potential to uncover the biologic foundations for understanding neurocognitive changes within the context of breast cancer and its treatment as well as the ability to understand how exercise mitigates these changes, there is a dearth of research on this topic. The purpose of this review article is to compile the research in these areas and to recommend potential areas of opportunity for investigation.

Role of eotaxin-1/CCL11 in sepsis-induced myocardial injury in elderly patients

Myocardial injury is a serious complication of sepsis. The present study aimed to identify potential biomarkers of sepsis-induced myocardial injury. Differentially expressed genes (DEGs) in patients and mice with sepsis-induced myocardial injury were identified via bioinformatic analysis. The identified DEG was tested in elderly patients with sepsis-induced myocardial injury. We identified 19 co-expressed DEGs. The most significant DEG was eotaxin-1/CCL11. We enrolled 25 controls without infections and 28 patients with sepsis-induced myocardial injury. Six of patients died within 30 days. Circulating eotaxin-1/CCL11 levels were significantly higher in patients with sepsis-induced myocardial injury than controls and were higher in non-survivors than survivors (both P < 0.01). Eotaxin-1/CCL11 was positively correlated with troponin I (r=0.48, P=0.01), B-type natriuretic peptide (BNP, r=0.44, P=0.02), and white blood cell (WBC) count (r=0.41, P=0.03). For the prediction of 30-day mortality, eotaxin-1/CCL11 had the greatest discriminatory ability (AUC 0.97) compared with troponin I (AUC 0.89), BNP (AUC 0.80), and WBC count (AUC 0.86). Taken together, eotaxin-1/CCL11 was upregulated in sepsis-injured myocardium and circulating eotaxin-1/CCL11 was a biomarker for predicting severity and mortality of elderly patients with sepsis-induced myocardial injury. These results suggest that eotaxin-1/CCL11 may become a useful biomarkers and potential therapeutic target for sepsis-induced myocardial injury.

The ageing epigenome and its rejuvenation

Ageing is characterized by the functional decline of tissues and organs and the increased risk of ageing-associated disorders. Several 'rejuvenating' interventions have been proposed to delay ageing and the onset of age-associated decline and disease to extend healthspan and lifespan. These interventions include metabolic manipulation, partial reprogramming, heterochronic parabiosis, pharmaceutical administration and senescent cell ablation. As the ageing process is associated with altered epigenetic mechanisms of gene regulation, such as DNA methylation, histone modification and chromatin remodelling, and non-coding RNAs, the manipulation of these mechanisms is central to the effectiveness of age-delaying interventions. This Review discusses the epigenetic changes that occur during ageing and the rapidly increasing knowledge of how these epigenetic mechanisms have an effect on healthspan and lifespan extension, and outlines questions to guide future research on interventions to rejuvenate the epigenome and delay ageing processes.

Inflammatory markers associated with fall recurrence and severity: The Bambuí Cohort Study of Aging

BACKGROUND

The aim of this study was to analyze the association between inflammatory markers and recurrent and severe falls in 1304 community-dwelling older adults from the Bambuí Cohort Study of Aging.

METHODS

Information about falls in the previous 12 months was collected, and classified based on recurrence (two or more falls) and severity (requirement of medical attention). The screened biomarkers included interleukins (IL-1β, IL-6, IL-10, and IL-12, TNF), chemokines (CXCL8, CXCL9, CXCL10, CCL2, and CCL5), and high-sensitive C-reactive protein (hs-PCR). Potential confounders included sociodemographic, behavioral, and health indicators. Associations were evaluated through logistic regression, using odds ratios (OR) and 95% confidence intervals (95% CI), with Stata 13.1.

RESULTS

The prevalence of recurrent and severe falls was 10.7% and 9.0%, respectively. After adjustments, elevated levels of IL-12 (OR: 1.92; 95% CI: 1.09-3.37) and CXCL9 (OR: 1.67; 95% CI: 1.05-2.66) were found to be associated with recurrent falls, while elevated levels of TNF (OR: 1.58; 95% CI: 1.01-2.50), IL-12 (OR: 2.04; 95% CI: 1.13-3.70), CXCL10 (OR: 1.75; 95% CI: 1.04-2.92), and CCL5 (OR: 1.90; 95% CI: 1.18-3.07) were associated with severe falls.

CONCLUSIONS

The results highlight a wide range of biomarkers not yet explored in the literature and suggest that inflammation may be an important component of recurrent and severe falls.

The Possible Role of Telomere Length and Chemokines in the Aging Process: A Transdiagnostic Review in Psychiatry

Background:

Psychiatric disorders are common, reaching a worldwide prevalence of 29.2%. They are associated with a high risk of premature death and with accelerated aging in clinical, molecular and neuroimaging studies. Recently, there is strong evidence suggesting a possible role of telomere length and chemokines in aging processes in psychiatric disorders.

Objective:

We aimed to review the literature on telomere length and chemokines and its association with early aging in mental illnesses on a transdiagnostic approach.

Results:

The review highlights the association between psychiatric disorders and early aging. Several independent studies have reported shorter telomere length and dysregulations on levels of circulating chemokines in schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorders, suggesting a complex interaction between these markers in a transdiagnostic level. However, studies have investigated the inflammatory markers and telomere shortening separately and associated with a particular diagnosis, rather than as a transdiagnostic biological feature.

Conclusion:

There is consistent evidence supporting the relationship between accelerated aging, telomere length, and chemokines in mental disorders, but they have been studied individually. Thus, more research is needed to improve the knowledge of accelerated senescence and its biomarkers in psychiatry, not only individually in each diagnosis, but also based on a transdiagnostic perspective. Moreover, further research should try to elucidate how the intricate association between the chemokines and telomeres together may contribute to the aging process in psychiatric disorders.

The current status of blood epigenetic biomarkers for dementia

Dementia is an overarching term which describes a group of symptoms that result in long-term decline in cognitive functioning that is significant enough to affect daily function. It is caused by a number of different diseases, the most common of which is Alzheimer's disease. Currently, there are no definitive biomarkers for preclinical or diagnostic use, or which differentiate between underlying disease types. The purpose of this review is to highlight several important areas of research on blood-based biomarkers of dementia, with a specific focus on epigenetic biomarkers. A systematic search of the literature identified 77 studies that compared blood DNA methylation between individuals with dementia and controls and 45 studies that measured microRNA. Very few studies were identified that focused on histone modifications. There were many promising findings from studies in the field of blood-based epigenetic biomarkers of dementia, however, a lack of consistency in study design, technologies, and platforms used for the biomarker measurement, as well as statistical analysis methods, have hampered progress. To date, there are very few findings that have been independently replicated across more than one study, indicating a preponderance of false-positive findings and the field has likely been plagued by positive publication bias. Here, we highlight and discuss several of the limitations of existing studies and provide recommendations for how these could be overcome in future research. A robust framework should be followed to enable development of the most valid and reproducible biomarkers with the strongest clinical utility. Defining a series of biomarkers that may be complimentary to each other could permit a stronger multifactorial biomarker to be developed that would allow for not only accurate dementia diagnosis but preclinical detection.

Pretreatment Cancer-Related Cognitive Impairment-Mechanisms and Outlook

Cognitive changes are common in patients with active cancer and during its remission. This has largely been blamed on therapy-related toxicities and diagnosis-related stress, with little attention paid to the biological impact of cancer itself. A plethora of clinical studies demonstrates that cancer patients experience cognitive impairment during and after treatment. However, recent studies show that a significant portion of patients with non-central nervous system (CNS) tumors experience cognitive decline prior to treatment, suggesting a role for tumor-derived factors in modulating cognition and behavior. Cancer-related cognitive impairment (CRCI) negatively impacts a patient’s quality of life, reduces occupational and social functioning, and increases morbidity and mortality. Furthermore, patients with cancer cachexia frequently experience a stark neurocognitive decline, suggesting peripheral tumors exert an enduring toll on the brain during this chronic paraneoplastic syndrome. However, the scarcity of research on cognitive impairment in non-CNS cancers makes it difficult to isolate psychosocial, genetic, behavioral, and pathophysiological factors in CRCI. Furthermore, clinical models of CRCI are frequently confounded by complicated drug regimens that inherently affect neurocognitive processes. The severity of CRCI varies considerably amongst patients and highlights its multifactorial nature. Untangling the biological aspects of CRCI from genetic, psychosocial, and behavioral factors is non-trivial, yet vital in understanding the pathogenesis of CRCI and discovering means for therapeutic intervention. Recent evidence demonstrating the ability of peripheral tumors to alter CNS pathways in murine models is compelling, and it allows researchers to isolate the underlying biological mechanisms from the confounding psychosocial stressors found in the clinic. This review summarizes the state of the science of CRCI independent of treatment and focuses on biological mechanisms in which peripheral cancers modulate the CNS.

The epigenetics of inflammaging: The contribution of age-related heterochromatin loss and locus-specific remodelling and the modulation by environmental stimuli

A growing amount of evidences indicates that inflammaging - the chronic, low grade inflammation state characteristic of the elderly - is the result of genetic as well as environmental or stochastic factors. Some of these, such as the accumulation of senescent cells that are persistent during aging or accompany its progression, seem to be sufficient to initiate the aging process and to fuel it. Others, like exposure to environmental compounds or infections, are temporary and resolve within a (relatively) short time. In both cases, however, a cellular memory of the event can be established by means of epigenetic modulation of the genome. In this review we will specifically discuss the relationship between epigenetics and inflammaging. In particular, we will show how age-associated epigenetic modifications concerned with heterochromatin loss and gene-specific remodelling, can promote inflammaging. Furthermore, we will recall how the exposure to specific nutritional, environmental and microbial stimuli can affect the rate of inflammaging through epigenetic mechanisms, touching also on the recent insight given by the concept of trained immunity.

Association between plasma CCL11 (eotaxin-1) and cognitive status in older adults: Differences between rural and urban dwellers

The chemokine CCL11 has been implicated in age-related cognitive deterioration in mice, yet evidence on the relationship between CCL11 and cognitive function in humans is limited. This study explored associations between CCL11 and cognition in rural and urban community-dwelling older adults. Participants were 515 urban dwellers from the 3C-Bordeaux cohort and 318 rural dwellers from the AMI cohort. Plasma CCL11 was measured using an enzyme-linked immunoassay. Mini Mental State Examination (MMSE) test scores were used as the main measure of cognitive performance. Multivariate regression analysis was used to evaluate the cross-sectional association between CCL11 and cognitive performance. CCL11 was significantly higher in rural dwellers compared to city dwellers (median [IQR]: 145 [115-201] pg/mL vs. 103 [85-129] pg/mL; p < 0.001). After adjustment for confounders, CCL11 was found to be negatively associated with cognitive performance in rural dwellers but not in city dwellers. These results suggest that CCL11 may be an independent determinant of cognitive function in older rural dwellers and that the residential environment modifies this association.