Klotho at the Edge of Alzheimer’s Disease and Senile Depression

Genes related to microglia polarization and immune infiltration in Alzheimer's Disease

Alzheimer's Disease (AD) remains a significant challenge due to its complex etiology and socio-economic burden. In this study, we investigated the roles of macrophage polarization-related hub genes in AD pathology, focusing on their impact on immune infiltration and gene regulation in distinct brain regions. Using Gene Expression Omnibus (GEO) datasets GSE110226 (choroid plexus) and GSE1297 (hippocampal CA1), we identified key genes-EDN1, HHLA2, KL, TREM2, and WWTR1-associated with AD mechanisms and immune responses. Based on these findings, we developed a diagnostic model demonstrating favorable calibration and clinical applicability. Furthermore, we explored molecular interactions within mRNA-transcription factor and mRNA-miRNA regulatory networks, providing deeper insights into AD progression and identifying potential therapeutic targets. The novel identification of WWTR1 and HHLA2 as biomarkers expands the diagnostic toolkit for AD, offering new perspectives on the disease's underlying immune dynamics. However, external dataset validation and further in vitro and in vivo studies are required to confirm these results and their clinical relevance.

Efficacy of selective serotonin reuptake inhibitors-related antidepressants in Alzheimer's disease: a meta-analysis

OBJECTIVE

To study the effects of selective serotonin reuptake inhibitors (SSRIs) on cognitive functions, mental improvements, and adverse effects in patients with Alzheimer's disease (AD).

METHODS

Registered in INPLASY (INPLASY202450004), five drugs (citalopram, s-citalopram, quetiapine, olanzapine, and sertraline) were selected as representatives. A comprehensive search was conducted in PubMed, EMBASE, Web of Science, and the Cochrane Library up to May 15, 2024. Search terms were combined using Boolean operators, specifically 'AND' between different categories (e.g., 'Alzheimer's Disease' AND 'SSRIs') and 'OR' within the same category (e.g., 'citalopram OR s-citalopram OR quetiapine OR olanzapine OR sertraline'), to ensure a thorough retrieval of relevant studies. The selection followed rigorous inclusion and exclusion criteria for meta-analysis.

RESULTS

Fourteen articles from 1118 were selected for meta-analysis. The indicators, including Neuropsychiatric Inventory (NPI), Mini-Mental State Examination (MMSE), Brief Psychiatric Rating Scale (BPRS), and Cornell Scale for Depression in Dementia (CSDD), were used to assess the effects of the drugs on AD treatment. According to the results of NPI, CSDD, BPRS, MMSE, and security assessments, the five antidepressants have significant advantages in AD treatment compared with placebo, while the MMSE of the patient treated with the antidepressants did not show notable changes compared with patients treated only with placebo. Statistical analyses were conducted using Review Manager 5.3, employing random-effects models to account for study heterogeneity and sensitivity analyses to test the robustness of our findings.

CONCLUSION

This study suggests that SSRI-related antidepressants have great potential values in AD treatment, and further research on the application of SSRI-related antidepressants in AD treatment is necessary.

Association between serum Klotho levels and hypothyroidism in older adults: NHANES 2007-2012

Whether Klotho plays any role in hypothyroidism is unknown. This study aimed to determine the relationship between serum Klotho levels and hypothyroidism in older adults. From the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES), 1444 older adults aged 65-79 were included in this cross-sectional study. Hypothyroidism was diagnosed using participants' reports of current medications and TSH tests. Klotho was measured using an enzyme-linked immunosorbent assay. The relationship between serum Klotho levels and hypothyroidism in older people was analyzed by one-way analysis of variance, multiple linear regression models, subgroup analyses, interaction tests, smoothed curve fitting, and threshold effects. A total of 209 (14.47%) participants were identified as having hypothyroidism. Serum Klotho (ln transformation) is independently and significantly negatively associated with the risk of hypothyroidism after complete adjustment for confounders (OR = 0.49, 95% CI 0.31-0.80; P = 0.0039). The results remained stable based on subgroup analyses and interaction tests. However, we observed an inverted U-shaped curve between the two using a smoothed curve fitting in the subgroups of 70 < age ≤ 75 years and females, with inflection points of 6.26 and 6.17, respectively. The results of our study indicate that serum Klotho levels negatively correlate with hypothyroidism among older adults.

Association of cognitive impairment with the interaction between chronic kidney disease and depression: findings from NHANES 2011-2014

BACKGROUND

Cognitive impairment (CoI), chronic kidney disease (CKD), and depression are prevalent among older adults and are interrelated, imposing a significant disease burden. This study evaluates the association of CKD and depression with CoI and explores their potential interactions.

METHOD

Data for this study were sourced from the 2011-2014 National Health and Nutritional Examination Survey (NHANES). Multiple binary logistic regression models assessed the relationship between CKD, depression, and CoI while controlling for confounders. The interactions were measured using the relative excess risk of interaction (RERI), the attributable proportion of interaction (AP), and the synergy index (S).

RESULTS

A total of 2,666 participants (weighted n = 49,251,515) were included in the study, of which 700 (16.00%) had CoI. After adjusting for confounding factors, the risk of CoI was higher in patients with CKD compared to non-CKD participants (odds ratio [OR] = 1.49, 95% confidence interval [CI]:1.12-1.99). The risk of CoI was significantly increased in patients with depression compared to those without (OR = 2.29, 95% CI: 1.73-3.03). Furthermore, there was a significant additive interaction between CKD and depression in terms of the increased risk of CoI (adjusted RERI = 2.01, [95% CI: 0.31-3.71], adjusted AP = 0.50 [95% CI: 0.25-0.75], adjusted S = 2.97 [95% CI: 1.27-6.92]).

CONCLUSION

CKD and depression synergistically affect CoI, particularly when moderate-to-severe depression co-occurs with CKD. Clinicians should be mindful of the combined impact on patients with CoI. Further research is needed to elucidate the underlying mechanisms and assess the effects specific to different CKD stages.

Distinguishing features of depression in dementia from primary psychiatric disease

Depression is a common and devastating neuropsychiatric symptom in the elderly and in patients with dementia. In particular, nearly 80% of patients with Alzheimer's Disease dementia experience depression during disease development and progression. However, it is unknown whether the depression in patients with dementia shares the same molecular mechanisms as depression presenting as primary psychiatric disease or occurs and persists through alternative mechanisms. In this review, we discuss how the clinical presentation and treatment differ between depression in dementia and as a primary psychiatric disease, with a focus on major depressive disorder. Then, we hypothesize several molecular mechanisms that may be unique to depression in dementia such as neuropathological changes, inflammation, and vascular events. Finally, we discuss existing issues and future directions for investigation and treatment of depression in dementia.

Analysis of the relationship between mild cognitive impairment and serum klotho protein and insulin-like growth factor-1 in the elderly

BACKGROUND

Mild cognitive impairment (MCI) is a mild memory or cognitive impairment.

OBJECTIVE

To explore the relationship between serum klotho (K1) protein and insulin-like growth factor-1 and mild cognitive impairment in the elderly in order to provide accurate and appropriate indicators for clinical diagnosis and treatment of MCI.

METHODS

This randomized stratified study adopted a multistage cluster sampling method. 161 elderly patients with mild cognitive impairment were included as the MCI group, and 161 healthy people matched with the MCI group in gender, age and education were selected as the control group.

RESULTS

The levels of serum K1 protein and insulin-like growth factor-1 in the MCI group were lower than those in the control group (P< 0.05). Both IGF-1 and K1 had predictive value for MCI (P< 0.05). The area under the curve (AUC) of IGF-1 for predicting MCI was 0.859 (95% CI: 0.790∼0.929), and the AUC of K1 for predicting MCI was 0.793 (95% CI: 0.694∼0.892). The value of joint prediction of the two indicators was the highest, with an AUC of 0.939 (95% CI: 0.896-0.993).

CONCLUSION

High serum K1 and insulin-like growth factor-1 are the protective factors of cognitive impairment in MCI patients. Both IGF-1 and serum K1 proteins have predictive value for MCI, and the combination of the two indicators has the highest predictive value.

The Importance of α-Klotho in Depression and Cognitive Impairment and Its Connection to Glutamate Neurotransmission-An Up-to-Date Review

Depression is a serious neuropsychiatric disease affecting an increasing number of people worldwide. Cognitive deficits (including inattention, poor memory, and decision-making difficulties) are common in the clinical picture of depression. Cognitive impairment has been hypothesized to be one of the most important components of major depressive disorder (MDD; referred to as clinical depression), although typical cognitive symptoms are less frequent in people with depression than in people with schizophrenia or bipolar disorder (BD; sometimes referred to as manic-depressive disorder). The importance of α-Klotho in the aging process has been well-documented. Growing evidence points to the role of α-Klotho in regulating other biological functions, including responses to oxidative stress and the modulation of synaptic plasticity. It has been proven that a Klotho deficit may contribute to the development of various nervous system pathologies, such as behavioral disorders or neurodegeneration. Given the growing evidence of the role of α-Klotho in depression and cognitive impairment, it is assumed that this protein may be a molecular link between them. Here, we provide a research review of the role of α-Klotho in depression and cognitive impairment. Furthermore, we propose potential mechanisms (related to oxidative stress and glutamatergic transmission) that may be important in α-Klotho-mediated regulation of mental and cognitive function.

Neuroprotective Role of Klotho on Dementia

Klotho, a gene found on chromosome 13q12, is involved in a variety of processes and signaling pathways in the human body related to vitamin D metabolism; cardiovascular, renal, musculoskeletal, and skin diseases; and cancer biology. However, more importantly, it has been linked to beneficial effects related to anti-aging. The levels of soluble Klotho in the blood have been found to decline with age, increasing the risk of age-related diseases. When the Klotho gene was silenced or defective, it caused a shorter lifespan. However, when the gene was overexpressed, it resulted in a longer lifespan. Klotho has positive benefits on the neurological system by causing a higher representation of useful longevity genes, preventing further neuronal damage, and offering neuroprotection. Thus, it has the potential to become a new treatment for many age-related diseases that cause dementia, including multiple sclerosis, Alzheimer's disease, and Parkinson's disease. In this review, we discuss the mechanisms of Klotho's benefits and roles on various organ systems, specifically on nervous system disorders that lead to dementia.

Sex differences in the association between serum α-Klotho and depression in middle-aged and elderly individuals: A cross-sectional study from NHANES 2007-2016

BACKGROUND

Klotho is a well-known anti-aging protein that exerts pleiotropic effects; however, little is known regarding serum α-Klotho in the context of depression. Here, we evaluated the association between serum α-Klotho levels and depression in middle-aged and older individuals.

METHODS

In this cross-sectional study, data were collected from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016 with a total of 5272 participants who were ≥40 years of age. Depression was evaluated using the 9-item Patient Health Questionnaire (PHQ-9). The association between serum α-Klotho levels and depression was determined on the basis of multivariable logistic regression models.

RESULTS

The mean age of the enrolled adults was 58.94 ± 10.54 years, of which 49.5 % were female. When serum α-Klotho was log10-transformed, it was significantly inversely associated with depression in females in the final adjusted model (odds ratio [OR], 0.32; 95 % confidence interval [CI], 0.12-0.85). In the contrast, serum α-Klotho (log10) was significantly positively associated with depression in males in one of the adjusted models (OR, 3.71; 95 % CI, 1.17-11.8), and this disappeared after adjusting other covariates (all P > 0.05). Based on further stratified respective analyses of females and males, the results were stable.

LIMITATIONS

The cross-sectional study could not yield any conclusions regarding causality.

CONCLUSIONS

In the present study, serum α-Klotho levels were negatively related to the prevalence of depression in middle-aged and elderly women. This study provides new evidence of sex differences in the association between serum α-Klotho levels and depression.

The fibroblast growth factor system in cognitive disorders and dementia

Cognitive impairment is the core precursor to dementia and other cognitive disorders. Current hypotheses suggest that they share a common pathological basis, such as inflammation, restricted neurogenesis, neuroendocrine disorders, and the destruction of neurovascular units. Fibroblast growth factors (FGFs) are cell growth factors that play essential roles in various pathophysiological processes via paracrine or autocrine pathways. This system consists of FGFs and their receptors (FGFRs), which may hold tremendous potential to become a new biological marker in the diagnosis of dementia and other cognitive disorders, and serve as a potential target for drug development against dementia and cognitive function impairment. Here, we review the available evidence detailing the relevant pathways mediated by multiple FGFs and FGFRs, and recent studies examining their role in the pathogenesis and treatment of cognitive disorders and dementia.

Novel approaches to increase synaptic resilience as potential treatments for Alzheimer's disease

A significant proportion of brains with Alzheimer's disease pathology are obtained from patients that were cognitively normal, suggesting that differences within the brains of these individuals made them resilient to the disease. Here, we describe recent approaches that specifically increase synaptic resilience, as loss of synapses is considered to be the first change in the brains of Alzheimer's patients. We start by discussing studies showing benefit from increased expression of neurotrophic factors and protective genes. Methods that effectively make dendritic spines stronger, specifically by acting through actin network proteins, scaffolding proteins and inhibition of phosphatases are described next. Importantly, the therapeutic strategies presented in this review tackle Alzheimer's disease not by targeting plaques and tangles, but instead by making synapses resilient to the pathology associated with Alzheimer's disease, which has tremendous potential.

The Circulating Level of Klotho Is Not Dependent upon Physical Fitness and Age-Associated Methylation Increases at the Promoter Region of the Klotho Gene

(1) Background: Higher levels of physical fitness are believed to increase the physiological quality of life and impact the aging process with a wide range of adaptive mechanisms, including the regulation of the expression of the age-associated klotho (KL) gene and protein levels. (2) Methods: Here, we tested the relationship between the DNA methylation-based epigenetic biomarkers PhenoAge and GrimAge and methylation of the promoter region of the KL gene, the circulating level of KL, and the stage of physical fitness and grip force in two groups of volunteer subjects, trained (TRND) and sedentary (SED), aged between 37 and 85 years old. (3) Results: The circulating KL level is negatively associated with chronological age in the TRND group (r = -0.19; p = 0.0295) but not in the SED group (r = -0.065; p = 0.5925). The age-associated decrease in circulating KL is partly due to the increased methylation of the KL gene. In addition, higher plasma KL is significantly related to epigenetic age-deceleration in the TRND group, assessed by the biomarker of PhenoAge (r = -0.21; p = 0.0192). (4) Conclusions: The level of physical fitness, on the other hand, does not relate to circulating KL levels, nor to the rate of the methylation of the promoter region of the KL gene, only in males.

The relationship between serum klotho and cognitive performance in a nationally representative sample of US adults

Purpose

Aging is the primary risk factor for cognitive decline. Serum klotho, as an anti-aging protein, may be involved in cognitive decline. Thus, we aim to explorer the correlation between serum klotho and cognitive performance among an older adult population in the United States.

Methods

We performed a cross-sectional study using data from NHANES 2011-2014. Serum klotho was analyzed by ELISA. Cognitive function was measured by Establish a Registry for Alzheimer's Disease (CERAD) test, Animal Fluency test and Digit Symbol Substitution Test (DSST) score. The relationship between serum klotho and cognition was analyzed by a multivariable regression model.

Results

A total of 2,171 participants aged 60-79 years were included. Median serum klotho concentration was 851.52 pg./ml (SD = 294.07). We also categorized serum klotho concentrates into quartiles. After fully adjusting pertinent variables, compared to those with lowest klotho levels (206.3-658.4 pg./ml), individuals with highest klotho concentrates (983.3-3,456 pg./ml) had a higher CERAD score [β (95%CI): 0.97 (0.25, 1.69) p = 0.008] and DSST score [β (95%CI): 1.86 (0.25, 3.47), p = 0.024].

Conclusion

Our findings indicated that, among the general population of American older adults, serum klotho concentrates may serve as a marker of cognitive health. The benefits of klotho on aging process and neurodegenerative disorders should be paid more attention.

Combined metabolic activators improve cognitive functions in Alzheimer's disease patients: a randomised, double-blinded, placebo-controlled phase-II trial

BACKGROUND

Alzheimer's disease (AD) is associated with metabolic abnormalities linked to critical elements of neurodegeneration. We recently administered combined metabolic activators (CMA) to the AD rat model and observed that CMA improves the AD-associated histological parameters in the animals. CMA promotes mitochondrial fatty acid uptake from the cytosol, facilitates fatty acid oxidation in the mitochondria, and alleviates oxidative stress.

METHODS

Here, we designed a randomised, double-blinded, placebo-controlled phase-II clinical trial and studied the effect of CMA administration on the global metabolism of AD patients. One-dose CMA included 12.35 g L-serine (61.75%), 1 g nicotinamide riboside (5%), 2.55 g N-acetyl-L-cysteine (12.75%), and 3.73 g L-carnitine tartrate (18.65%). AD patients received one dose of CMA or placebo daily during the first 28 days and twice daily between day 28 and day 84. The primary endpoint was the difference in the cognitive function and daily living activity scores between the placebo and the treatment arms. The secondary aim of this study was to evaluate the safety and tolerability of CMA. A comprehensive plasma metabolome and proteome analysis was also performed to evaluate the efficacy of the CMA in AD patients.

RESULTS

We showed a significant decrease of AD Assessment Scale-cognitive subscale (ADAS-Cog) score on day 84 vs day 0 (P = 0.00001, 29% improvement) in the CMA group. Moreover, there was a significant decline (P = 0.0073) in ADAS-Cog scores (improvement of cognitive functions) in the CMA compared to the placebo group in patients with higher ADAS-Cog scores. Improved cognitive functions in AD patients were supported by the relevant alterations in the hippocampal volumes and cortical thickness based on imaging analysis. Moreover, the plasma levels of proteins and metabolites associated with NAD + and glutathione metabolism were significantly improved after CMA treatment.

CONCLUSION

Our results indicate that treatment of AD patients with CMA can lead to enhanced cognitive functions and improved clinical parameters associated with phenomics, metabolomics, proteomics and imaging analysis. Trial registration ClinicalTrials.gov NCT04044131 Registered 17 July 2019, https://clinicaltrials.gov/ct2/show/NCT04044131.

Klotho an Autophagy Stimulator as a Potential Therapeutic Target for Alzheimer’s Disease: A Review

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease; it is the most common cause of senile dementia. Klotho, a single-pass transmembrane protein primarily generated in the brain and kidney, is active in a variety of metabolic pathways involved in controlling neurodegeneration and ageing. Recently, many studies have found that the upregulation of Klotho can improve pathological cognitive deficits in an AD mice model and have demonstrated that Klotho plays a role in the induction of autophagy, a major contributing factor for AD. Despite the close association between Klotho and neurodegenerative diseases, such as AD, the underlying mechanism by which Klotho contributes to AD remains poorly understood. In this paper, we will introduce the expression, location and structure of Klotho and its biological functions. Specifically, this review is devoted to the correlation of Klotho protein and the AD phenotype, such as the effect of Klotho in upregulating the amyloid-beta clearance and in inducing autophagy for the clearance of toxic proteins, by regulating the autophagy lysosomal pathway (ALP). In summary, the results of multiple studies point out that targeting Klotho would be a potential therapeutic strategy in AD treatment.

Assessing the joint effects of brain aging and gut microbiota on the risks of psychiatric disorders

We aim to explore the potential interaction effects of brain aging and gut microbiota on the risks of sleep, anxiety and depression disorders. The genome-wide association study (GWAS) datasets of brain aging (N = 21,407) and gut microbiota (N = 3,890) were obtained from published studies. Individual level genotype and phenotype data of psychiatric traits (including sleep, anxiety and depression) were all from the UK Biobank (N = 107,947-374,505). We first calculated the polygenic risk scores (PRS) of 62 brain aging modes and 114 gut microbiota taxa as the instrumental variables, and then constructed linear and logistic regression analyses to systematically explore the potential interaction effects of brain aging and gut microbiota on psychiatric disorders. We observed the interaction effects of brain aging and gut microbiota on sleep, anxiety and depression disorders, such as Putamen/caudate T2* vs. Rhodospirillales (β = -0.012, P = 8.4 × 10^-4) was negatively associated with chronotype, Fornix MD vs. Holdemanella (β = -0.007, P = 1.76 × 10^-2) was negatively related to general anxiety disorder (GAD) scores, and White matter lesions vs. Acidaminococcaceae (β = 0.019, P = 1.29 × 10^-3) was positively correlated with self-reported depression. Interestingly, Putamen volume vs. Intestinibacter was associated with all three psychiatric disorders, including chronotype (negative correlation), GAD scores (positive correlation) and self-reported depression (positive correlation). Our study results suggest the significant impacts of brain aging and gut microbiota on the development of sleep, anxiety and depression disorders, providing new clues for clarifying the pathogenesis of these disorders.

SAMP8 Mice as a Model of Age-Related Cognition Decline with Underlying Mechanisms in Alzheimer's Disease

Alzheimer's disease (AD) is a highly age-related cognitive decline frequently attacking the elderly. Senescence-accelerated mouse-prone 8 (SAMP8) is an ideal model to study AD, displaying age-related learning and memory disorders. SAMP8 mice exhibit most features of pathogenesis of AD, including an abnormal expression of anti-aging factors, oxidative stress, inflammation, amyloid-β (Aβ) deposits, tau hyperphosphorylation, endoplasmic reticulum stress, abnormal autophagy activity, and disruption of intestinal flora. SAMP8 mice, therefore, have visualized the understanding of AD, and also provided effective ways to find new therapeutic targets. This review focused on the age-related pathogenesis in SAMP8 mice, to advance the understanding of age-related learning and memory decline and clarify the mechanisms. Furthermore, this review will provide extensive foundations for SAMP8 mice used in therapeutics for AD.

Mechanisms of cognitive dysfunction in CKD

Cognitive impairment is an increasingly recognized major cause of chronic disability and is commonly found in patients with chronic kidney disease (CKD). Knowledge of the relationship between kidney dysfunction and impaired cognition may improve our understanding of other forms of cognitive dysfunction. Patients with CKD are at an increased risk (compared with the general population) of both dementia and its prodrome, mild cognitive impairment (MCI), which are characterized by deficits in executive functions, memory and attention. Brain imaging in patients with CKD has revealed damage to white matter in the prefrontal cortex and, in animal models, in the subcortical monoaminergic and cholinergic systems, accompanied by widespread macrovascular and microvascular damage. Unfortunately, current interventions that target cardiovascular risk factors (such as anti-hypertensive drugs, anti-platelet agents and statins) seem to have little or no effect on CKD-associated MCI, suggesting that the accumulation of uraemic neurotoxins may be more important than disturbed haemodynamic factors or lipid metabolism in MCI pathogenesis. Experimental models show that the brain monoaminergic system is susceptible to uraemic neurotoxins and that this system is responsible for the altered sleep pattern commonly observed in patients with CKD. Neural progenitor cells and the glymphatic system, which are important in Alzheimer disease pathogenesis, may also be involved in CKD-associated MCI. More detailed study of CKD-associated MCI is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention, and whether there may be novel approaches and potential therapies with wider application to this and other forms of cognitive decline.

Klotho Pathways, Myelination Disorders, Neurodegenerative Diseases, and Epigenetic Drugs

In this review we outline a rationale for identifying neuroprotectants aimed at inducing endogenous Klotho activity and expression, which is epigenetic action, by definition. Such an approach should promote remyelination and/or stimulate myelin repair by acting on mitochondrial function, thereby heralding a life-saving path forward for patients suffering from neuroinflammatory diseases. Disorders of myelin in the nervous system damage the transmission of signals, resulting in loss of vision, motion, sensation, and other functions depending on the affected nerves, currently with no effective treatment. Klotho genes and their single-pass transmembrane Klotho proteins are powerful governors of the threads of life and death, true to the origin of their name, Fates, in Greek mythology. Among its many important functions, Klotho is an obligatory co-receptor that binds, activates, and/or potentiates critical fibroblast growth factor activity. Since the discovery of Klotho a little over two decades ago, it has become ever more apparent that when Klotho pathways go awry, oxidative stress and mitochondrial dysfunction take over, and age-related chronic disorders are likely to follow. The physiological consequences can be wide ranging, potentially wreaking havoc on the brain, eye, kidney, muscle, and more. Central nervous system disorders, neurodegenerative in nature, and especially those affecting the myelin sheath, represent worthy targets for advancing therapies that act upon Klotho pathways. Current drugs for these diseases, even therapeutics that are disease modifying rather than treating only the symptoms, leave much room for improvement. It is thus no wonder that this topic has caught the attention of biomedical researchers around the world.

Anti-ageing gene therapy: Not so far away?

Improving healthspan is the main objective of anti-ageing research. Currently, innovative gene therapy-based approaches seem to be among the most promising for preventing and treating chronic polygenic pathologies, including age-related ones. The gene-based therapy allows to modulate the genome architecture using both direct (e.g., by gene editing) and indirect (e.g., by viral or non-viral vectors) approaches. Nevertheless, considering the extraordinary complexity of processes involved in ageing and ageing-related diseases, the effectiveness of these therapeutic options is often unsatisfactory and limited by their side-effects. Thus, clinical implementation of such applications is certainly a long-time process that will require many translation phases for addressing challenges. However, after overcoming these issues, their implementation in clinical practice may obviously provide new possibilities in anti-ageing medicine. Here, we review and discuss recent advances in this rapidly developing research field.

Intra- and intergenerational changes in the cortical DNA methylome in response to therapeutic intermittent hypoxia in mice

Recent evidence from our laboratory documents functional resilience to retinal ischemic injury in untreated mice derived from parents exposed to repetitive hypoxic conditioning (RHC) before breeding. To begin to understand the epigenetic basis of this intergenerational protection, we used methylated DNA immunoprecipitation and sequencing to identify genes with differentially methylated promoters (DMGPs) in the prefrontal cortex of mice treated directly with the same RHC stimulus (F0-RHC) and in the prefrontal cortex of their untreated F1-generation offspring (F1-*RHC). Subsequent bioinformatic analyses provided key mechanistic insights into how changes in gene expression secondary to promoter hypo- and hypermethylation might afford such protection within and across generations. We found extensive changes in DNA methylation in both generations consistent with the expression of many survival-promoting genes, with twice the number of DMGPs in the cortex of F1*RHC mice relative to their F0 parents that were directly exposed to RHC. In contrast to our hypothesis that similar epigenetic modifications would be realized in the cortices of both F0-RHC and F1-*RHC mice, we instead found relatively few DMGPs common to both generations; in fact, each generation manifested expected injury resilience via distinctly unique gene expression profiles. Whereas in the cortex of F0-RHC mice, predicted protein-protein interactions reflected activation of an anti-ischemic phenotype, networks activated in F1-*RHC cortex comprised networks indicative of a much broader cytoprotective phenotype. Altogether, our results suggest that the intergenerational transfer of an acquired phenotype to offspring does not necessarily require the faithful recapitulation of the conditioning-modified DNA methylome of the parent.

Validation of a priori candidate Alzheimer's disease SNPs with brain amyloid-beta deposition

The accumulation of brain amyloid β (Aβ) is one of the main pathological hallmarks of Alzheimer’s disease (AD). However, the role of brain amyloid deposition in the development of AD and the genetic variants associated with this process remain unclear. In this study, we sought to identify associations between Aβ deposition and an a priori evidence based set of 1610 genetic markers, genotyped from 505 unrelated individuals (258 Aβ+ and 247 Aβ−) enrolled in the Australian Imaging, Biomarker & Lifestyle (AIBL) study. We found statistically significant associations for 6 markers located within intronic regions of 6 genes, including AC103796.1-BDNF, PPP3R1, NGFR, KL, ABCA7 & CALHM1. Although functional studies are required to elucidate the role of these genes in the accumulation of Aβ and their potential implication in AD pathophysiology, our findings are consistent with results obtained in previous GWAS efforts.