Assessment of Advanced Glycation End Products and Receptors and the Risk of Dementia

Osteoporosis and Alzheimer´s disease (or Alzheimer´s disease and Osteoporosis)

Alzheimer's disease (AD) and osteoporosis are two diseases that mainly affect elderly people, with increases in the occurrence of cases due to a longer life expectancy. Several epidemiological studies have shown a reciprocal association between both diseases, finding an increase in incidence of osteoporosis in patients with AD, and a higher burden of AD in osteoporotic patients. This epidemiological relationship has motivated the search for molecules, genes, signaling pathways and mechanisms that are related to both pathologies. The mechanisms found in these studies can serve to improve treatments and establish better patient care protocols.

Diabetes mellitus and risk of incident dementia in APOE ɛ4 carriers: an updated meta-analysis

BACKGROUND AND AIM

Diabetes raises the risk of dementia, mortality, and cognitive decline in the elderly, potentially because of hereditary variables such as APOE. In this study, we aim to evaluate Diabetes mellitus and the risk of incident dementia in APOE ɛ4 carriers.

METHOD

We thoroughly searched PubMed (Medline), Scopus, and Google Scholar databases for related articles up to September 2023. The titles, abstracts, and full texts of articles were reviewed; data were extracted and analyzed.

RESULT

This meta-analysis included nine cohorts and seven cross-sectional articles with a total of 42,390 population. The study found that APOE ɛ4 carriers with type 2 diabetes (T2D) had a 48% higher risk of developing dementia compared to non-diabetic carriers (Hazard Ratio;1.48, 95%CI1.36-1.60). The frequency of dementia was 3 in 10 people (frequency: 0.3; 95%CI (0.15-0.48). No significant heterogeneity was observed. Egger's test, which we performed, revealed no indication of publication bias among the included articles (p = 0.2).

CONCLUSION

Overall, diabetes increases the risk of dementia, but further large-scale studies are still required to support the results of current research.

Hypertension, Neurodegeneration, and Cognitive Decline

Elevated blood pressure is a well-established risk factor for age-related cognitive decline. Long linked to cognitive impairment on vascular bases, increasing evidence suggests a potential association of hypertension with the neurodegenerative pathology underlying Alzheimer disease. Hypertension is well known to disrupt the structural and functional integrity of the cerebral vasculature. However, the mechanisms by which these alterations lead to brain damage, enhance Alzheimer pathology, and promote cognitive impairment remain to be established. Furthermore, critical questions concerning whether lowering blood pressure by antihypertensive medications prevents cognitive impairment have not been answered. Recent developments in neurovascular biology, brain imaging, and epidemiology, as well as new clinical trials, have provided insights into these critical issues. In particular, clinical and basic findings on the link between neurovascular dysfunction and the pathobiology of neurodegeneration have shed new light on the overlap between vascular and Alzheimer pathology. In this review, we will examine the progress made in the relationship between hypertension and cognitive impairment and, after a critical evaluation of the evidence, attempt to identify remaining knowledge gaps and future research directions that may advance our understanding of one of the leading health challenges of our time.

Intake of dietary advanced glycation end products may be associated with depression and sleep quality in young adults

BACKGROUND

This study examined the relationship between dietary intake of advanced glycation end products (dAGEs) and depression and sleep quality in young adults.

METHODS

This study, which included 420 university students (F = 80.2 %; M = 19.8 %), is observational and cross-sectional. Dietary AGEs intakes of individuals were taken with a 24-h food consumption record system. Measuring the depression status of the participants was evaluated with the Beck Depression Inventory (BDI), and the assessment of their sleep quality was evaluated with the Pittsburg Sleep Quality Index (PSQI). Individuals' dAGEs intakes were divided into three equal groups (low, medium, and high). The energy was adjusted in all analyzes of dAGEs intake. Study data were analyzed with the SPSS (27.0 version) and GraphPad program (8.0 version).

RESULTS

The BDI and PSQI total score averages of individuals in the high dAGEs intake group were higher than the other groups, and this difference was statistically significant (p < 0.001). There is no significant difference between individuals' dAGEs intakes and energy and macronutrient intakes. Students' dAGEs intake was affected by BDI (β = 0.722, 95 % Cl = 0.639;0.811) and PSQI (β = 0.286, 95 % Cl = 0.179;0.431) scores (p < 0.001). This effect persisted even when various confounding factors were included (age, gender, smoking, body mass index, chronic disease) (p < 0.001).

LIMITATIONS

These data are cross-sectional, which limits the generalizability of results and establishing cause-effect relationships.

CONCLUSION

There may be an association between dAGEs intake and the development of depression and sleep quality in young adults. Clinical intervention studies using objective measurement methods should be conducted on this issue in the future.

Associations of Serum Insulin and Related Measures With Neuropathology and Cognition in Older Persons With and Without Diabetes

OBJECTIVE

To examine associations of serum insulin and related measures with neuropathology and cognition in older persons.

METHODS

We studied 192 older persons (96 with diabetes and 96 without, matched by sex and balanced by age-at-death, education, and postmortem interval) from a community-based, clinical-pathologic study of aging, with annual evaluations including neuropsychological testing (summarized into global cognition and 5 cognitive domains) and postmortem autopsy. We assessed serum insulin, glucose, leptin, adiponectin, hemoglobin A1C, advanced glycation-end products (AGEs), and receptors for advanced glycation-end products, and calculated the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and adiponectin-to-leptin ratio. Using adjusted regression analyses, we examined the associations of serum measures with neuropathology of cerebrovascular disease and Alzheimer's disease, and with the level of cognition proximate-to-death.

RESULTS

Higher HOMA-IR was associated with the presence of brain infarcts and specifically microinfarcts, and higher HOMA-IR and leptin were each associated with subcortical infarcts. Further, higher leptin levels and lower adiponectin-to-leptin ratios were associated with the presence of moderate-to-severe atherosclerosis. Serum insulin and related measures were not associated with the level of Alzheimer's disease pathology, as assessed by global, as well as amyloid burden or tau tangle density scores. Regarding cognitive outcomes, higher insulin and leptin levels, and lower adiponectin and receptors for advanced glycation-end products levels, respectively, were each associated with lower levels of global cognition.

INTERPRETATION

Peripheral insulin resistance indicated by HOMA-IR and related serum measures was associated with a greater burden of cerebrovascular neuropathology and lower cognition. ANN NEUROL 2024;95:665-676.

The AGE-RAGE axis associates with chronic pulmonary diseases and smoking in the Rotterdam study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma associate with high morbidity and mortality. High levels of advanced glycation end products (AGEs) were found in tissue and plasma of COPD patients but their role in COPD and asthma is unclear.

METHODS

In the Rotterdam Study (n = 2577), AGEs (by skin autofluorescence (SAF)), FEV1 and lung diffusing capacity (DLCOc and DLCOc /alveolar volume [VA]) were measured. Associations of SAF with asthma, COPD, GOLD stage, and lung function were analyzed using logistic and linear regression adjusted for covariates, followed by interaction and stratification analyses. sRAGE and EN-RAGE associations with COPD prevalence were analyzed by logistic regression.

RESULTS

SAF associated with COPD prevalence (OR = 1.299 [1.060, 1.591]) but not when adjusted for smoking (OR = 1.106 [0.89, 1.363]). SAF associated with FEV1% predicted (β=-3.384 [-4.877, -1.892]), DLCOc (β=-0.212 [-0.327, -0.097]) and GOLD stage (OR = 4.073, p = 0.001, stage 3&4 versus 1). Stratified, the association between SAF and FEV1%predicted was stronger in COPD (β=-6.362 [-9.055, -3.670]) than non-COPD (β=-1.712 [-3.306, -0.118]). Association of SAF with DLCOc and DLCOc/VA were confined to COPD (β=-0.550 [-0.909, -0.191]; β=-0.065 [-0.117, -0.014] respectively). SAF interacted with former smoking and COPD prevalence for associations with lung function. Lower sRAGE and higher EN-RAGE associated with COPD prevalence (OR = 0.575[0.354, 0.931]; OR = 1.778[1.142, 2.768], respectively).

CONCLUSIONS

Associations between SAF, lung function and COPD prevalence were strongly influenced by smoking. SAF associated with COPD severity and its association with lung function was more prominent within COPD. These results fuel further research into interrelations and causality between SAF, smoking and COPD.

TAKE-HOME MESSAGE

Skin AGEs associated with prevalence and severity of COPD and lung function in the general population with a stronger effect in COPD, calling for further research into interrelations and causality between SAF, smoking and COPD.

Shared Proteins and Pathways of Cardiovascular and Cognitive Diseases: Relation to Vascular Cognitive Impairment

One of the primary goals of systems medicine is the detection of putative proteins and pathways involved in disease progression and pathological phenotypes. Vascular cognitive impairment (VCI) is a heterogeneous condition manifesting as cognitive impairment resulting from vascular factors. The precise mechanisms underlying this relationship remain unclear, which poses challenges for experimental research. Here, we applied computational approaches like systems biology to unveil and select relevant proteins and pathways related to VCI by studying the crosstalk between cardiovascular and cognitive diseases. In addition, we specifically included signals related to oxidative stress, a common etiologic factor tightly linked to aging, a major determinant of VCI. Our results show that pathways associated with oxidative stress are quite relevant, as most of the prioritized vascular cognitive genes and proteins were enriched in these pathways. Our analysis provided a short list of proteins that could be contributing to VCI: DOLK, TSC1, ATP1A1, MAPK14, YWHAZ, CREB3, HSPB1, PRDX6, and LMNA. Moreover, our experimental results suggest a high implication of glycative stress, generating oxidative processes and post-translational protein modifications through advanced glycation end-products (AGEs). We propose that these products interact with their specific receptors (RAGE) and Notch signaling to contribute to the etiology of VCI.

Skin autofluorescence, reflecting accumulation of advanced glycation end products, and the risk of dementia in a population-based cohort

Conditions such as hyperglycemia and oxidative stress lead to the formation of advanced glycation end products (AGEs), which are harmful compounds that have been implicated in dementia. Within the Rotterdam Study, we measured skin AGEs as skin autofluorescence, reflecting long-term accumulation of AGEs, and determined their association with the risk of dementia and with brain magnetic resonance imaging (MRI) measures. Skin autofluorescence was measured between 2013 and 2016 in 2922 participants without dementia. Of these, 1504 also underwent brain MRI, on which measures of brain atrophy and cerebral small vessel disease were assessed. All participants were followed for the incidence of dementia until 2020. Of 2922 participants (mean age 72.6 years, 57% women), 123 developed dementia. Higher skin autofluorescence (per standard deviation) was associated with an increased risk of dementia (hazard ratio 1.21 [95% confidence interval 1.01-1.46]) and Alzheimer's disease (1.19 [0.97-1.47]), independently of age and other studied potential confounders. Stronger effects were seen in apolipoprotein E (APOE) ε4 carriers (1.34 [0.98-1.82]) and in participants with diabetes (1.35 [0.94-1.94]). Participants with higher skin autofluorescence levels also had smaller total brain volumes and smaller hippocampus volumes on MRI, and they had more often lacunes. These results suggest that AGEs may be involved in dementia pathophysiology.

Communal interaction of glycation and gut microbes in diabetes mellitus, Alzheimer's disease, and Parkinson's disease pathogenesis

Diabetes and its complications, Alzheimer's disease (AD), and Parkinson's disease (PD) are increasing gradually, reflecting a global threat vis-à-vis expressing the essentiality of a substantial paradigm shift in research and remedial actions. Protein glycation is influenced by several factors, like time, temperature, pH, metal ions, and the half-life of the protein. Surprisingly, most proteins associated with metabolic and neurodegenerative disorders are generally long-lived and hence susceptible to glycation. Remarkably, proteins linked with diabetes, AD, and PD share this characteristic. This modulates protein's structure, aggregation tendency, and toxicity, highlighting renovated attention. Gut microbes and microbial metabolites marked their importance in human health and diseases. Though many scientific shreds of evidence are proposed for possible change and dysbiosis in gut flora in these diseases, very little is known about the mechanisms. Screening and unfolding their functionality in metabolic and neurodegenerative disorders is essential in hunting the gut treasure. Therefore, it is imperative to evaluate the role of glycation as a common link in diabetes and neurodegenerative diseases, which helps to clarify if modulation of nonenzymatic glycation may act as a beneficial therapeutic strategy and gut microbes/metabolites may answer some of the crucial questions. This review briefly emphasizes the common functional attributes of glycation and gut microbes, the possible linkages, and discusses current treatment options and therapeutic challenges.

Association of Advanced Glycation End Products with Cognitive Function: HealthyDance Study

Background

The current research on advanced glycosylation end products (AGEs) and cognitive function is limited.

Objective

We aimed to investigate the relationship between multiple plasma AGEs and cognitive function and mild cognitive impairment (MCI).

Methods

Baseline data from The Lifestyle and Healthy Aging of Chinese Square Dancer Study was used in this cross-sectional study. Ultra-high-performance liquid chromatography tandem mass spectrometry was used to determine plasma levels of carboxymethyl lysine (CML), carboxyethyl lysine (CEL), and methyl imidazolinone (MG-H1). Four cognitive tests were used to obtain the four cognitive domain scores and the composite z scores. The Petersen criteria were used to diagnose MCI. The data were analyzed by multivariable linear and logistic regression models.

Results

This study included 1,018 participants (median age 61.0 years, 87.3% female). After multivariate adjustment, the βs of the highest quartile of CML and CEL compared to the lowest quartile were -0.28 (-0.38, -0.17) and -0.13 (-0.23, -0.03), respectively, for the composite z score. For the four cognitive domains, CML was negatively correlated with memory, attention, and executive function, and CEL was negatively associated with memory and language function. In addition, higher CML was associated with a higher odds of MCI. MG-H1 was not associated with cognitive function.

Conclusions

High plasma AGE levels were correlated with poorer cognitive function, particularly CML and CEL, higher levels of CML were also associated with higher odds of MCI. To clarify the effects of different AGEs on cognitive function and the underlying mechanisms, further longitudinal and experimental studies are needed.

Pathophysiological Aspects and Therapeutic Armamentarium of Alzheimer's Disease: Recent Trends and Future Development

Alzheimer's disease (AD) is the primary cause of dementia and is characterized by the death of brain cells due to the accumulation of insoluble amyloid plaques, hyperphosphorylation of tau protein, and the formation of neurofibrillary tangles within the cells. AD is also associated with other pathologies such as neuroinflammation, dysfunction of synaptic connections and circuits, disorders in mitochondrial function and energy production, epigenetic changes, and abnormalities in the vascular system. Despite extensive research conducted over the last hundred years, little is established about what causes AD or how to effectively treat it. Given the severity of the disease and the increasing number of affected individuals, there is a critical need to discover effective medications for AD. The US Food and Drug Administration (FDA) has approved several new drug molecules for AD management since 2003, but these drugs only provide temporary relief of symptoms and do not address the underlying causes of the disease. Currently, available medications focus on correcting the neurotransmitter disruption observed in AD, including cholinesterase inhibitors and an antagonist of the N-methyl-D-aspartate (NMDA) receptor, which temporarily alleviates the signs of dementia but does not prevent or reverse the course of AD. Research towards disease-modifying AD treatments is currently underway, including gene therapy, lipid nanoparticles, and dendrimer-based therapy. These innovative approaches aim to target the underlying pathological processes of AD rather than just managing the symptoms. This review discusses the novel aspects of pathogenesis involved in the causation of AD of AD and in recent developments in the therapeutic armamentarium for the treatment of AD such as gene therapy, lipid nanoparticles, and dendrimer-based therapy, and many more.

Targeting redox imbalance in neurodegeneration: characterizing the role of GLP-1 receptor agonists

Reactive oxygen species (ROS) have emerged as essential signaling molecules regulating cell survival, death, inflammation, differentiation, growth, and immune response. Environmental factors, genetic factors, or many pathological condition such as diabetes increase the level of ROS generation by elevating the production of advanced glycation end products, reducing free radical scavengers, increasing mitochondrial oxidative stress, and by interfering with DAG-PKC-NADPH oxidase and xanthine oxidase pathways. Oxidative stress, and therefore the accumulation of intracellular ROS, determines the deregulation of several proteins and caspases, damages DNA and RNA, and interferes with normal neuronal function. Furthermore, ROS play an essential role in the polymerization, phosphorylation, and aggregation of tau and amyloid-beta, key mediators of cognitive function decline. At the neuronal level, ROS interfere with the DNA methylation pattern and various apoptotic factors related to cell death, promoting neurodegeneration. Only few drugs are able to quench ROS production in neurons. The cross-linking pathways between diabetes and dementia suggest that antidiabetic medications can potentially treat dementia. Among antidiabetic drugs, glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been found to reduce ROS generation and ameliorate mitochondrial function, protein aggregation, neuroinflammation, synaptic plasticity, learning, and memory. The incretin hormone glucagon-like peptide-1 (GLP-1) is produced by the enteroendocrine L cells in the distal intestine after food ingestion. Upon interacting with its receptor (GLP-1R), it regulates blood glucose levels by inducing insulin secretion, inhibiting glucagon production, and slowing gastric emptying. No study has evidenced a specific GLP-1RA pathway that quenches ROS production. Here we summarize the effects of GLP-1RAs against ROS overproduction and discuss the putative efficacy of Exendin-4, Lixisenatide, and Liraglutide in treating dementia by decreasing ROS.

Higher dietary advanced glycation products intake is associated with increased risk of dementia, independent from genetic predisposition

BACKGROUND

Dietary advanced glycation end products (AGEs) might exert adverse effects on cognition. The associations between dietary AGEs and long-term risk of dementia are yet to be assessed in large population studies. We aimed to explore whether elevated dietary AGEs intake is associated with increased risk of dementia, and whether this association might be affected by genetic risk.

METHODS

A prospective cohort study, which included a total of 93,830 participants (aged≥ 50 years) free from dementia at baseline of the UK Biobank study (2006-2010) and had at least two 24-h dietary assessments and were followed up until 2021. Dietary AGEs, including Nε-(1-Carboxyethyl)-l-lysine (CEL), Nε-(carboxymethyl) lysine (CML), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were estimated via averaged data from the multiple 24-h food assessments according to the ultra-performance LC-tandem MS based dAGEs database. Incidence of all-cause dementia was ascertained through hospital inpatient and mortality records. Multivariable Cox regression models were utilized to estimate hazards ratios (HRs) and 95% confidence interval (CI) of dementia risk associated with dietary AGEs.

RESULTS

During a median follow-up of 11.9 years, 728 participants developed dementia. In multivariable adjusted model, when comparing the highest with the lowest tertile of intake level, HRs (95% CI) of dementia were 1.43 (1.16, 1.76) for total AGEs Z score, 1.53 (1.25, 1.89) for CEL, 1.27 (1.03, 1.56) for CML and 1.24 (1.02, 1.52) for MG-H1 (all P trend<0.01). There was no significant interaction between dietary AGEs intake, genetic risk and APOE ε4 carrier status for dementia.

CONCLUSIONS

Higher intakes of dietary AGEs including CEL, CML and MG-H1 were associated with a higher risk of dementia, independent from genetic risk, highlighting the significance of dietary AGEs restriction for dementia prevention.

Association between Urinary AGEs and Circulating miRNAs in Children and Adolescents with Overweight and Obesity from the Italian I.Family Cohort: A Pilot Study

Modern dietary habits are linked to high exposure to Advanced Glycation End products (AGEs) mainly due to the dramatic increase in the consumption of highly processed foods in recent years. Body levels of these compounds vary with food intake and are almost interconnected with age and health status, formally embodying indicators of oxidative stress and inflammation in adults. However, the relationship between AGEs and health issues has not been definitively understood in children, and several pediatric investigations have produced conflicting evidence. Besides, despite extensive research, there are no universally accepted analytical techniques for measuring AGE levels in the human body, with several approaches available, each with its advantages and disadvantages. This pilot study aimed to investigate the association between urinary AGEs, measured using spectrofluorimetry-based assays, and circulating microRNAs (c-miRNAs) in a subsample (n = 22) of Italian children participating in the I.Family Study. Anthropometric measurements, biochemical markers, and miRNA profiles were assessed. The first indication of a relationship between urinary AGEs and c-miRNAs in the context of obesity was found. Specifically, four miRNAs, hsa-miR-10b-5p, hsa-miR-501-5p, hsa-miR-874-3p, and hsa-miR-2355-5p were significantly associated with levels of urinary AGEs. The association between AGEs, obesity, inflammation markers, and specific miRNAs highlights the complex interplay between these factors and their potential impact on cellular and tissue homeostasis. The discovery of altered c-miRNAs profiling has the potential to offer innovative methods for assessing early changes in the body's AGE pool and allow recognition of an increased risk of disease susceptibility, routinely undetected until metabolic complications are identified.

Preventive Effect of Indian Gooseberry (Phyllanthus emblica L.) Fruit Extract on Cognitive Decline in High-Fat Diet (HFD)-Fed Rats

SCOPE

Methylglyoxal (MG)-derived advanced glycation end products (AGEs) directly bind to the receptor for advanced glycation end products (RAGE), subsequently exacerbating obesity and obesity-induced cognitive decline. Indian gooseberry (Phyllanthus emblica L.) fruit has antiobesity properties. However, the underlying mechanism by which Indian gooseberry fruit prevents obesity-induced cognitive decline remains unclear.

METHODS AND RESULTS

This study aims to investigate the preventive effect of a water extract of Indian gooseberry fruit (WEIG) and its bioactive compound gallic acid (GA) on the obesity-induced cognitive decline through MG suppression and gut microbiota modulation in high-fat diet (HFD)-fed rats. Trapping MG, WEIG, and GA significantly ameliorate fat accumulation in adipose tissue and learning and memory deficits. Mechanistically, WEIG and GA administration effectively reduces brain MG and AGE levels and subsequently reduces insulin resistance, inflammatory cytokines, MDA production, and Alzheimer's disease-related proteins, but increases both antioxidant enzyme activities and anti-inflammatory cytokine with inhibiting RAGE, MAPK, and NF-κB levels in HFD-fed rats. Additionally, WEIG and GA supplementation increases the relative abundances of Bacteroidetes, Gammaproteobacteria, and Parasutterella, which negatively correlate with MG, inflammatory cytokine, and Alzheimer's disease-related protein expressions.

CONCLUSION

This novel finding provides a possible mechanism by which WEIG prevents obesity-induced cognitive decline through the gut-brain axis.

Advanced Glycation End-Products and Their Effects on Gut Health

Dietary advanced glycation end-products (AGEs) are a heterogeneous group of compounds formed when reducing sugars are heated with proteins, amino acids, or lipids at high temperatures for a prolonged period. The presence and accumulation of AGEs in numerous cell types and tissues are known to be prevalent in the pathology of many diseases. Modern diets, which contain a high proportion of processed foods and therefore a high level of AGE, cause deleterious effects leading to a multitude of unregulated intracellular and extracellular signalling and inflammatory pathways. Currently, many studies focus on investigating the chemical and structural aspects of AGEs and how they affect the metabolism and the cardiovascular and renal systems. Studies have also shown that AGEs affect the digestive system. However, there is no complete picture of the implication of AGEs in this area. The gastrointestinal tract is not only the first and principal site for the digestion and absorption of dietary AGEs but also one of the most susceptible organs to AGEs, which may exert many local and systemic effects. In this review, we summarise the current evidence of the association between a high-AGE diet and poor health outcomes, with a special focus on the relationship between dietary AGEs and alterations in the gastrointestinal structure, modifications in enteric neurons, and microbiota reshaping.

Hypertension, Neurovascular Dysfunction, and Cognitive Impairment

Hypertension affects a significant proportion of the adult and aging population and represents an important risk factor for vascular cognitive impairment and late-life dementia. Chronic high blood pressure continuously challenges the structural and functional integrity of the cerebral vasculature, leading to microvascular rarefaction and dysfunction, and neurovascular uncoupling that typically impairs cerebral blood supply. Hypertension disrupts blood-brain barrier integrity, promotes neuroinflammation, and may contribute to amyloid deposition and Alzheimer pathology. The mechanisms underlying these harmful effects are still a focus of investigation, but studies in animal models have provided significant molecular and cellular mechanistic insights. Remaining questions relate to whether adequate treatment of hypertension may prevent deterioration of cognitive function, the threshold for blood pressure treatment, and the most effective antihypertensive drugs. Recent advances in neurovascular biology, advanced brain imaging, and detection of subtle behavioral phenotypes have begun to provide insights into these critical issues. Importantly, a parallel analysis of these parameters in animal models and humans is feasible, making it possible to foster translational advancements. In this review, we provide a critical evaluation of the evidence available in experimental models and humans to examine the progress made and identify remaining gaps in knowledge.

Chrysin-phospholipid complex-based solid dispersion for improved anti-aging and neuroprotective effects in mice

The present study aimed to improve the neuroprotective effect of chrysin (CHR) by combining two formulation techniques, phospholipid (PL) complexation and solid dispersion (SD). CHR-phospholipid complex (CHR-PLC) was prepared through solvent evaporation. The molar ratio CHR/PL (1:3), which exhibited the highest complexation efficiency, was selected for the preparation of CHR-PLC loaded SD (CHR-PLC-SD) with 2-hydroxypropyl β cyclodextrin (2-HPβCD) and polyvinylpyrrolidone 8000. CHR-PLC/2-HPβCD (1:2, w/w) displayed the highest aqueous solubility of CHR (5.86 times more than that of plain CHR). CHR-SD was also prepared using 2-HPβCD for comparison. The in vitro dissolution of CHR-PLC-SD4 revealed an enhancement in the dissolution rate over CHR-PLC (1:3), CHR-SD, and plain CHR by six times. The optimum formulations and plain CHR were evaluated for their neuroprotective effect on brain aging induced by D-galactose in mice. The results demonstrated a behavioral activity elevation, an increase of AMPK, LKB1, and PGC1α brain contents as well as a reduction of AGEs, GFAP, NT-3, TNF-α, and NF-κβ brain contents when compared with those of the D-galactose control group. Thus, the developed formulations stimulated neurogenesis and mitochondrial biogenesis as well as suppressed neuroinflammation and neurodegeneration. The order of activity was as follows: CHR-PLC-SD4 > CHR-PLC (1:3) > CHR-SD > plain CHR.

Prevailing Antagonistic Risks in Pleiotropic Associations with Alzheimer's Disease and Diabetes

BACKGROUND

The lack of efficient preventive interventions against Alzheimer's disease (AD) calls for identifying efficient modifiable risk factors for AD. As diabetes shares many pathological processes with AD, including accumulation of amyloid plaques and neurofibrillary tangles, insulin resistance, and impaired glucose metabolism, diabetes is thought to be a potentially modifiable risk factor for AD. Mounting evidence suggests that links between AD and diabetes may be more complex than previously believed.

OBJECTIVE

To examine the pleiotropic architecture of AD and diabetes mellitus (DM).

METHODS

Univariate and pleiotropic analyses were performed following the discovery-replication strategy using individual-level data from 10 large-scale studies.

RESULTS

We report a potentially novel pleiotropic NOTCH2 gene, with a minor allele of rs5025718 associated with increased risks of both AD and DM. We confirm previously identified antagonistic associations of the same variants with the risks of AD and DM in the HLA and APOE gene clusters. We show multiple antagonistic associations of the same variants with AD and DM in the HLA cluster, which were not explained by the lead SNP in this cluster. Although the ɛ2 and ɛ4 alleles played a major role in the antagonistic associations with AD and DM in the APOE cluster, we identified non-overlapping SNPs in this cluster, which were adversely and beneficially associated with AD and DM independently of the ɛ2 and ɛ4 alleles.

CONCLUSION

This study emphasizes differences and similarities in the heterogeneous genetic architectures of AD and DM, which may differentiate the pathogenic mechanisms of these diseases.

Receptor for Advanced Glycation End Product, Organ Crosstalk, and Pathomechanism Targets for Comprehensive Molecular Therapeutics in Diabetic Ischemic Stroke

Diabetes mellitus, a well-established risk factor for stroke, is related to higher mortality and poorer outcomes following the stroke event. Advanced glycation end products(AGEs), their receptors RAGEs, other ligands, and several other processes contribute to the cerebrovascular pathomechanism interaction in the diabetes-ischemic stroke combination. Critical reappraisal of molecular targets and therapeutic agents to mitigate them is required to identify key elements for therapeutic interventions that may improve patient outcomes. This scoping review maps evidence on the key roles of AGEs, RAGEs, other ligands such as Leukotriene B4 (LTB4), High-mobility group box 1 (HMGB1) nuclear protein, brain-kidney-muscle crosstalk, alternate pathomechanisms in neurodegeneration, and cognitive decline related to diabetic ischemic stroke. RAGE, HMGB1, nitric oxide, and polyamine mechanisms are important therapeutic targets, inflicting common consequences of neuroinflammation and oxidative stress. Experimental findings on a number of existing-emerging therapeutic agents and natural compounds against key targets are promising. The lack of large clinical trials with adequate follow-up periods is a gap that requires addressing to validate the emerging therapeutic agents. Five therapeutic components, which include agents to mitigate the AGE-RAGE axis, improved biomarkers for risk stratification, better renal dysfunction management, adjunctive anti-inflammatory-antioxidant therapies, and innovative neuromuscular stimulation for rehabilitation, are identified. A comprehensive therapeutic strategy that features all the identified components is needed for outcome improvement in diabetic stroke patients.

Severe Neuro-COVID is associated with peripheral immune signatures, autoimmunity and neurodegeneration: a prospective cross-sectional study

Growing evidence links COVID-19 with acute and long-term neurological dysfunction. However, the pathophysiological mechanisms resulting in central nervous system involvement remain unclear, posing both diagnostic and therapeutic challenges. Here we show outcomes of a cross-sectional clinical study (NCT04472013) including clinical and imaging data and corresponding multidimensional characterization of immune mediators in the cerebrospinal fluid (CSF) and plasma of patients belonging to different Neuro-COVID severity classes. The most prominent signs of severe Neuro-COVID are blood-brain barrier (BBB) impairment, elevated microglia activation markers and a polyclonal B cell response targeting self-antigens and non-self-antigens. COVID-19 patients show decreased regional brain volumes associating with specific CSF parameters, however, COVID-19 patients characterized by plasma cytokine storm are presenting with a non-inflammatory CSF profile. Post-acute COVID-19 syndrome strongly associates with a distinctive set of CSF and plasma mediators. Collectively, we identify several potentially actionable targets to prevent or intervene with the neurological consequences of SARS-CoV-2 infection.

Pharmacological thiamine levels as a therapeutic approach in Alzheimer's disease

of the study.

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.

The Effects of Dietary Advanced Glycation End-Products on Neurocognitive and Mental Disorders

Advanced glycation end products (AGEs) are glycated proteins or lipids formed endogenously in the human body or consumed through diet. Ultra-processed foods and some culinary techniques, such as dry cooking methods, represent the main sources and drivers of dietary AGEs. Tissue accumulation of AGEs has been associated with cellular aging and implicated in various age-related diseases, including type-2 diabetes and cardiovascular disease. The current review summarizes the literature examining the associations between AGEs and neurocognitive and mental health disorders. Studies indicate that elevated circulating AGEs are cross-sectionally associated with poorer cognitive function and longitudinally increase the risk of developing dementia. Additionally, preliminary studies show that higher skin AGE accumulation may be associated with mental disorders, particularly depression and schizophrenia. Potential mechanisms underpinning the effects of AGEs include elevated oxidative stress and neuroinflammation, which are both key pathogenetic mechanisms underlying neurodegeneration and mental disorders. Decreasing dietary intake of AGEs may improve neurological and mental disorder outcomes. However, more sophisticated prospective studies and analytical approaches are required to verify directionality and the extent to which AGEs represent a mediator linking unhealthy dietary patterns with cognitive and mental disorders.

Effect of Cannabidiol on the Neural Glyoxalase Pathway Function and Longevity of Several C. elegans Strains Including a C. elegans Alzheimer's Disease Model

Cannabidiol is a nonpsychoactive phytocannabinoid produced by the Cannabis sativa plant and possesses a wide range of pharmacological activities, including anti-inflammatory, antioxidant, and neuroprotective activities. Cannabidiol functions in a neuroprotective manner, in part through the activation of cellular antioxidant pathways. The glyoxalase pathway detoxifies methylglyoxal, a highly reactive metabolic byproduct that can accumulate in the brain, and contributes to the severity of neurodegenerative diseases, including Alzheimer's disease. While cannabidiol's antioxidant properties have been investigated, it is currently unknown how it may modulate the glyoxalase pathway. In this research paper, we examine the effects of Cannabidiol on cerebellar neurons and in several Caenorhabditis elegans strains. We determined that a limited amount of Cannabidiol can prevent methylglyoxal-mediated cellular damage through enhancement of the neural glyoxalase pathway and extend the lifespan and survival of C. elegans, including a transgenic C. elegans strain modeling Alzheimer's disease.

Shared Molecular Mechanisms among Alzheimer’s Disease, Neurovascular Unit Dysfunction and Vascular Risk Factors: A Narrative Review

Alzheimer’s disease (AD) is the most common type of dementia, affecting 24 million individuals. Clinical and epidemiological studies have found several links between vascular risk factors (VRF), neurovascular unit dysfunction (NVUd), blood-brain barrier breakdown (BBBb) and AD onset and progression in adulthood, suggesting a pathogenetic continuum between AD and vascular dementia. Shared pathways between AD, VRF, and NVUd/BBB have also been found at the molecular level, underlining the strength of this association. The present paper reviewed the literature describing commonly shared molecular pathways between adult-onset AD, VRF, and NVUd/BBBb. Current evidence suggests that VRF and NVUd/BBBb are involved in AD neurovascular and neurodegenerative pathology and share several molecular pathways. This is strongly supportive of the hypothesis that the presence of VRF can at least facilitate AD onset and progression through several mechanisms, including NVUd/BBBb. Moreover, vascular disease and several comorbidities may have a cumulative effect on VRF and worsen the clinical manifestations of AD. Early detection and correction of VRF and vascular disease by improving NVUd/BBBd could be a potential target to reduce the overall incidence and delay cognitive impairment in AD.

Protein degradation-associated mechanisms that are affected in Alzheimer´s disease

Alzheimer's disease (AD) is the most common type of dementia associated with age-related neurodegeneration. Alteration of several molecular mechanisms has been correlated with the progression of AD. In recent years, dysregulation of proteostasis-associated pathways has emerged as a potential risk factor for neurodegenerative diseases. This review investigated the ubiquitin-proteasome system, lysosome-associated degradation, endoplasmic-reticulum-associated degradation, and the formation of advanced glycation end products. These pathways involved in proteostasis have been reported to be altered in AD, suggesting that their study may be critical for identifying new biomarkers and target molecules for AD.

Role and Therapeutic Potential of RAGE Signaling in Neurodegeneration

Activation of the receptor for advanced glycation end products (RAGE) has been shown to play an active role in the development of multiple neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. Although originally identified as a receptor for advanced glycation end products, RAGE is a pattern recognition receptor able to bind multiple ligands. The final outcome of RAGE signaling is defined in a context and cell type specific manner and can exert both neurotoxic and neuroprotective functions. Contributing to the complexity of the RAGE signaling network, different RAGE isoforms with distinctive signaling capabilities have been described. Moreover, multiple RAGE ligands bind other receptors and RAGE antagonism can significantly affect their signaling. Here, we discuss the outcome of celltype specific RAGE signaling in neurodegenerative pathologies. In addition, we will review the different approaches that have been developed to target RAGE signaling and their therapeutic potential. A clear understanding of the outcome of RAGE signaling in a cell type- and disease-specific manner would contribute to advancing the development of new therapies targeting RAGE. The ability to counteract RAGE neurotoxic signaling while preserving its neuroprotective effects would be critical for the success of novel therapies targeting RAGE signaling.

Advanced glycation end product intake during pregnancy and offspring allergy outcomes: A Prospective cohort study

BACKGROUND

Associations have been shown between concurrent assessment of dietary intake of advanced glycation end products (AGEs) and childhood allergic outcomes. We examined the association between maternal AGEs intake and development of offspring asthma, wheeze, atopic dermatitis, allergic rhinitis and food allergies, and sought to determine whether the intake of AGEs was associated with cord sera cytokines/chemokines.

METHODS

Pregnant women ≥16 years were recruited in the Healthy Start study, a prospective pre-birth cohort from Colorado (N = 1410). The analysis included 962 dyads with adequate diet (≥2 recalls) and allergy outcome details. AGEs intake was estimated for each mother by matching intakes reported using 24-h dietary recalls during pregnancy to a reference database of commonly consumed foods' AGEs values. Child diagnoses of asthma and allergies up to 8 years were obtained from electronic medical records. Cord sera cytokines and chemokines were analysed in a subset (N = 462) of children.

RESULTS

The median [IQR] AGEs intake for the overall sample was 11,919 kU/day [8293, 16,573]. Unadjusted analysis showed a positive association between maternal AGEs intake in pregnancy and rhinitis up to 8 years of age (HR = 1.03; 95% CI: 1.01, 1.06), but the association was attenuated and no longer significant in adjusted models (HR = 1.01; 95% CI: 0.98, 1.04). Both adjusted and unadjusted models showed no associations between AGEs intake in pregnancy and any of the other outcomes (p > .05). There were no significant associations between any cytokine or chemokine measured and AGEs intake or any of the outcomes studied (p > .05).

CONCLUSION

The study showed that maternal AGEs intake was not associated with offspring asthma and allergy outcomes. AGEs exposure during pregnancy may not have the same impact on child development as postnatal exposure.

Linking Oxidative Stress and Proteinopathy in Alzheimer's Disease

Proteinopathy and excessive production of reactive oxygen species (ROS), which are the principal features observed in the Alzheimer’s disease (AD) brain, contribute to neuronal toxicity. β-amyloid and tau are the primary proteins responsible for the proteinopathy (amyloidopathy and tauopathy, respectively) in AD, which depends on ROS production; these aggregates can also generate ROS. These mechanisms work in concert and reinforce each other to drive the pathology observed in the aging brain, which primarily involves oxidative stress (OS). This, in turn, triggers neurodegeneration due to the subsequent loss of synapses and neurons. Understanding these interactions may thus aid in the identification of potential neuroprotective therapies that could be clinically useful. Here, we review the role of β-amyloid and tau in the activation of ROS production. We then further discuss how free radicals can influence structural changes in key toxic intermediates and describe the putative mechanisms by which OS and oligomers cause neuronal death.

Modifiable Risk Factors in Alzheimer Disease and Related Dementias: A Review

PURPOSE

Although Alzheimer disease and related dementias (ADRDs) have long been considered nonpreventable and even an inevitable consequence of aging, recent findings from longitudinal studies indicate a downtrend in age-adjusted incidence and prevalence of ADRDs in Western countries. This remarkable trend might be the result of improved management of so-called modifiable risk factors. The aim of this review is to present evidence of modifiable factors of ADRDs in a life-course approach.

METHODS

A PubMed database search was conducted between November and December 2020 to identify relevant studies evaluating the role of modifiable risk factors in the development of ADRDs. Key words (Alzheimer's disease and modifiable risk factors) were used and specific inclusion and exclusion criteria applied.

FINDINGS

This review identifies modifiable factors for ADRDs divided into early-life, middle-life, and late-life risk factors, depending on the available window of preventive action. According to life course exposure, factors can be protective or deleterious for ADRDs that participate in the underlying pathophysiologic complexity of these diseases as well as the complexity for public health measures implementations.

IMPLICATIONS

The available evidence derived from epidemiologic, preclinical, interventional studies suggest that modifiable risk factors for ADRDs offer opportunities for therapeutic and preventive actions.

The use of the soluble receptor for advanced glycation-end products (sRAGE) as a potential biomarker of disease risk and adverse outcomes

The soluble receptor for advanced glycation end-products (sRAGE) has been classically considered a sink for pro-inflammatory RAGE ligands and as such has been associated with protection from inflammatory stress and disease. An alternative, though not mutually exclusive view is that high levels of sRAGE in circulation reflect the overstimulation of cell surface RAGE which if persistent, lead to the amplification of pro-inflammatory processes and the exacerbation of pathological states. With these two scenarios in mind this review focuses on the potential role of sRAGE as a prospective biomarker of disease risk and adverse outcomes.

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The prognostic value of measuring sRAGE levels in blood is subjected to debate.

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Raised sRAGE levels may result from the overstimulation of cell surface RAGE.

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Raised sRAGE may reflect chronic inflammation and multimorbidity rather than a healthy state.

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sRAGE is a promising biomarker of disease risk and adverse outcomes.