Insulin-like Growth Factor-1 and IGF Binding Proteins Predict All-Cause Mortality and Morbidity in Older Adults

The Quest for Eternal Youth: Hallmarks of Aging and Rejuvenating Therapeutic Strategies

The impressive achievements made in the last century in extending the lifespan have led to a significant growth rate of elderly individuals in populations across the world and an exponential increase in the incidence of age-related conditions such as cardiovascular diseases, diabetes mellitus type 2, and neurodegenerative diseases. To date, geroscientists have identified 12 hallmarks of aging (genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, mitochondrial dysfunction, impaired nutrient sensing, cellular senescence, stem cell exhaustion, defective intercellular communication, chronic inflammation, and gut dysbiosis), intricately linked among each other, which can be targeted with senolytic or senomorphic drugs, as well as with more aggressive approaches such as cell-based therapies. To date, side effects seriously limit the use of these drugs. However, since rejuvenation is a dream of mankind, future research is expected to improve the tolerability of the available drugs and highlight novel strategies. In the meantime, the medical community, healthcare providers, and society should decide when to start these treatments and how to tailor them individually.

Tartrate-resistant acid phosphatase (TRAP/ACP5) promotes bone length, regulates cortical and trabecular bone mass, and maintains growth plate architecture and width in a sex- and site-specific manner in mice

Tartrate-resistant acid phosphatase (TRAP) serum levels reflect osteoclast number, bone remodeling activity, and fracture risk. Deletion or loss of function of TRAP results in short stature in mice and man. Yet, the impact and mechanisms of TRAP for the site- and sex-specific development of bone and cartilage is not well understood. Here, we use a global TRAP knockout (TRAPKO) and wildtype littermate control (WT) mice of both sexes to investigate TRAP as a possible sex- and site-specific regulator of bone and growth plate development. TRAPKO mice of both sexes weighed less and had shorter tibial length than their WT, features that were more accentuated in male than female TRAPKO mice. These changes were not associated with a general reduction in growth as not all organs displayed a proportionally lower mass, and serum IGF-1 was unchanged. Using μCT and site-specificity analysis of the cortical bone revealed wider proximal tibia, a higher trabecular thickness, and lower trabecular separation in male TRAPKO compared to WT mice, an effect not seen in female mice. Histomorphometric analysis revealed that the growth plate height as well as height of terminal hypertrophic chondrocytes were markedly increased, and the number of columns was decreased in TRAPKO mice of both sexes. These effects were more accentuated in female mice. Proliferation and differentiation of bone marrow derived macrophages into osteoclasts, as well as C-terminal cross links were normal in TRAPKO mice of both sexes. Collectively, our results show that TRAP regulates bone and cartilage development in a sex-and site-specific manner in mice.

Identification of functional rare coding variants in IGF-1 gene in humans with exceptional longevity

Diminished signaling via insulin/insulin-like growth factor-1 (IGF-1) axis is associated with longevity in different model organisms. IGF-1 gene is highly conserved across species, with only few evolutionary changes identified in it. Despite its potential role in regulating lifespan, no coding variants in IGF-1 have been reported in human longevity cohorts to date. This study investigated the whole exome sequencing data from 2,487 individuals in a cohort of Ashkenazi Jewish centenarians, their offspring, and controls without familial longevity to identify functional IGF-1 coding variants. We identified two likely functional coding variants IGF-1:p.Ile91Leu and IGF-1:p.Ala118Thr in our longevity cohort. Notably, a centenarian specific novel variant IGF-1:p.Ile91Leu was located at the binding interface of IGF-1 - IGF-1R, whereas IGF-1:p.Ala118Thr was significantly associated with lower circulating levels of IGF-1. We performed extended all-atom molecular dynamics simulations to evaluate the impact of Ile91Leu on stability, binding dynamics and energetics of IGF-1 bound to IGF-1R. The IGF-1:p.Ile91Leu formed less stable interactions with IGF-1R's critical binding pocket residues and demonstrated lower binding affinity at the extracellular binding site compared to wild-type IGF-1. Our findings suggest that IGF-1:p.Ile91Leu and IGF-1:p.Ala118Thr variants attenuate IGF-1R activity by impairing IGF-1 binding and diminishing the circulatory levels of IGF-1, respectively. Consequently, diminished IGF-1 signaling resulting from these variants may contribute to exceptional longevity in humans.

The effect of IGFBP3 gene knockout by the CRISPR/Cas9 system on the IGF-1 pathway in murine cells

BACKGROUND

The IGF-1 signaling pathway has been deeply involved in the aging mechanism. The insulin-like growth factor binding protein 3 (IGFBP-3) is a protein that binds to IGF-1 that regulates growth, survival, and aging.

OBJECTIVE

The purpose of this study was to investigate the impact of the IGFBP3 gene knockout (KO) on the expressions of aging-related proteins and genes using the CRISPR/Cas9 system.

METHODS

The IGFBP3 gene knockout (KO) was performed by the CRISPR/Cas9 system. Sanger DNA sequencing and Indel analyses were used to verify the induction of mutation.

RESULTS

First, Sanger DNA sequencing was used to analyze the IGFBP3 gene knockout in murine cells (B16F1). The isolation of three colonies with the mutated DNA sequences in the IGFBP3 gene was validated. In addition, the expression levels of the IGFBP3 gene and protein in the edited B16F1 cells were lower than in those of normal B16F1 cells in western blot analysis as well as RT-PCR and qPCR. Moreover, IGFBP3 gene KO cells enhanced the level of SA-ß-gal staining and short telomere length compared to normal B16F1 cells. In particular, it was found that the expression levels of senescence-related proteins such as PI3K, AKT1, PDK1, and p53 were higher in IGFBP3 gene KO cells than in normal cells in both the absence and presence of IGF-1.

CONCLUSIONS

Therefore, the above findings could provide a clue that IGFBP3 could play a key role in the aging mechanism.

The vasoprotective role of IGF-1 signaling in the cerebral microcirculation: prevention of cerebral microhemorrhages in aging

Aging is closely associated with various cerebrovascular pathologies that significantly impact brain function, with cerebral small vessel disease (CSVD) being a major contributor to cognitive decline in the elderly. Consequences of CSVD include cerebral microhemorrhages (CMH), which are small intracerebral bleeds resulting from the rupture of microvessels. CMHs are prevalent in aging populations, affecting approximately 50% of individuals over 80, and are linked to increased risks of vascular cognitive impairment and dementia (VCID). Hypertension is a primary risk factor for CMHs. Vascular smooth muscle cells (VSMCs) adapt to hypertension by undergoing hypertrophy and producing extracellular matrix (ECM) components, which reinforce vessel walls. Myogenic autoregulation, which involves pressure-induced constriction, helps prevent excessive pressure from damaging the vulnerable microvasculature. However, aging impairs these adaptive mechanisms, weakening vessel walls and increasing susceptibility to damage. Insulin-like Growth Factor 1 (IGF-1) is crucial for vascular health, promoting VSMC hypertrophy, ECM production, and maintaining normal myogenic protection. IGF-1 also prevents microvascular senescence, reduces reactive oxygen species (ROS) production, and regulates matrix metalloproteinase (MMP) activity, which is vital for ECM remodeling and stabilization. IGF-1 deficiency, common in aging, compromises these protective mechanisms, increasing the risk of CMHs. This review explores the vasoprotective role of IGF-1 signaling in the cerebral microcirculation and its implications for preventing hypertension-induced CMHs in aging. Understanding and addressing the decline in IGF-1 signaling with age are crucial for maintaining cerebrovascular health and preventing hypertension-related vascular injuries in the aging population.

Cognitive reserve proxies are associated with age-related cognitive decline - Not age-related gait speed decline

Cognition and gait share brain substrates in aging and dementia. Cognitive reserve (CR) allows individuals to cope with brain pathology and delay cognitive impairment and dementia. Yet, evidence for that CR is associated with age-related cognitive decline is mixed, and evidence for that CR is associated with age-related gait decline is limited. In 1,079 older (M Age = 75.4 years; 56.0% women) LonGenity study participants without dementia at baseline and up to 12 years of annual follow-up (M follow-up = 3.9 years, SD = 2.5 years), high CR inferred from cognitive (education years), physical (number of blocks walked per day; weekly physical activity days), and social (volunteering/working; living with someone) proxies were associated with slower rates of age-related decline in global cognition - not gait speed decline. Thus, cognitive, physical, and social CR proxies are associated with cognitive decline in older adults without dementia. The multifactorial etiology and earlier decline in gait than cognition may render it less modifiable by CR proxies later in life.

Feasible mechanisms and therapeutic potential of food probiotics to mitigate diabetes‐associated cancers: A comprehensive review and in silico validation

People with diabetes mellitus (DM) and hyperglycemia are linked with cancer risk. Diabetes and cancer have been corroborated by high morbidity and mortality rates. Studies revealed that elevated levels of insulin secretions trigger insulin‐like growth factor 1 (IGF‐1) production. Moreover, IGF‐1 is a key regulator involved in promoting cancer cell progression and is linked with DM. Cancer drug resistance and ototoxic effects can adversely affect the health and lifespan of an individual. However, naturally derived bioactive compounds are gaining attention for their nontoxic properties and specific behavior. Likewise, probiotics have also been regarded as safe and successful alternatives to treat DM‐linked cancers. The present review aims to highlight the therapeutic potential and feasible functions of probiotics to mitigate or inhibit DM‐associated cancers. Meanwhile, the intracellular signaling cascades involved in promoting DM‐linked cancer are enumerated for future prospective research. However, metabolomics interactions and protein–protein interactions are to be discussed for deeper insights into affirmative principles in diabetic‐linked cancers. Drug discovery and innovative preclinical evaluation need further adjuvant and immune‐enhancement therapies. Furthermore, the results of the in silico assessment could provide scientific excellence of IGF‐1 in diabetes and cancer. Overall, this review summarizes the mechanistic insights and therapeutic targets for diabetes‐associated cancer.

Developmentally dynamic changes in DNA methylation in the human pancreas

Development of the human pancreas requires the precise temporal control of gene expression via epigenetic mechanisms and the binding of key transcription factors. We quantified genome-wide patterns of DNA methylation in human fetal pancreatic samples from donors aged 6 to 21 post-conception weeks. We found dramatic changes in DNA methylation across pancreas development, with > 21% of sites characterized as developmental differentially methylated positions (dDMPs) including many annotated to genes associated with monogenic diabetes. An analysis of DNA methylation in postnatal pancreas tissue showed that the dramatic temporal changes in DNA methylation occurring in the developing pancreas are largely limited to the prenatal period. Significant differences in DNA methylation were observed between males and females at a number of autosomal sites, with a small proportion of sites showing sex-specific DNA methylation trajectories across pancreas development. Pancreas dDMPs were not distributed equally across the genome and were depleted in regulatory domains characterized by open chromatin and the binding of known pancreatic development transcription factors. Finally, we compared our pancreas dDMPs to previous findings from the human brain, identifying evidence for tissue-specific developmental changes in DNA methylation. This study represents the first systematic exploration of DNA methylation patterns during human fetal pancreas development and confirms the prenatal period as a time of major epigenomic plasticity.

IGF‑1 inhibits palmitic acid‑induced mitochondrial apoptosis in macrophages

Insulin growth factor‑1 (IGF‑1) is an endocrine regulator that plays an important role in normal growth and development. IGF‑1 mediated effects may result in protecting macrophages from immunometabolic response. However, it is unclear whether IGF‑1 has a protective effect on fatty acid‑induced macrophages damage. In the present study, THP‑1 cells were differentiated into macrophages and stimulated with palmitic acid (PA) in the absence or presence of IGF‑1. Macrophages apoptosis was measured by Cell Counting Kit‑8 assay, flow cytometry, Hoechst 33342 staining and western blotting. The mitochondrial damage was evaluated using JC‑1 staining and mitochondrial reactive oxygen species detection. The activation of mitophagy was assessed using immunofluorescence and western blotting. As a result, IGF‑1 significantly restored the survival rate in macrophages, while the apoptosis was inhibited through mitochondrial pathway. In addition, IGF‑1 protected the mitochondrial damage induced by PA. Furthermore, PA induced mitophagy via phosphatase and tensin homolog‑induced putative kinase protein 1/Parkin, which was reversed by IGF‑1. Taken together, the present study demonstrated the protective effect of IGF‑1 on PA‑induced mitochondrial apoptosis in macrophages, which might provide a potential therapeutic strategy for treatment of lipotoxicity.

Ketosis Suppression and Ageing (KetoSAge): The Effects of Suppressing Ketosis in Long Term Keto-Adapted Non-Athletic Females

Most studies on ketosis have focused on short-term effects, male athletes, or weight loss. Hereby, we studied the effects of short-term ketosis suppression in healthy women on long-standing ketosis. Ten lean (BMI 20.5 ± 1.4), metabolically healthy, pre-menopausal women (age 32.3 ± 8.9) maintaining nutritional ketosis (NK) for > 1 year (3.9 years ± 2.3) underwent three 21-day phases: nutritional ketosis (NK; P1), suppressed ketosis (SuK; P2), and returned to NK (P3). Adherence to each phase was confirmed with daily capillary D-beta-hydroxybutyrate (BHB) tests (P1 = 1.9 ± 0.7; P2 = 0.1 ± 0.1; and P3 = 1.9 ± 0.6 pmol/L). Ageing biomarkers and anthropometrics were evaluated at the end of each phase. Ketosis suppression significantly increased: insulin, 1.78-fold from 33.60 (± 8.63) to 59.80 (± 14.69) pmol/L (p = 0.0002); IGF1, 1.83-fold from 149.30 (± 32.96) to 273.40 (± 85.66) µg/L (p = 0.0045); glucose, 1.17-fold from 78.6 (± 9.5) to 92.2 (± 10.6) mg/dL (p = 0.0088); respiratory quotient (RQ), 1.09-fold 0.66 (± 0.05) to 0.72 (± 0.06; p = 0.0427); and PAI-1, 13.34 (± 6.85) to 16.69 (± 6.26) ng/mL (p = 0.0428). VEGF, EGF, and monocyte chemotactic protein also significantly increased, indicating a pro-inflammatory shift. Sustained ketosis showed no adverse health effects, and may mitigate hyperinsulinemia without impairing metabolic flexibility in metabolically healthy women.

Novel small molecules inhibit proteotoxicity and inflammation: Mechanistic and therapeutic implications for Alzheimer's Disease, healthspan and lifespan- Aging as a consequence of glycolysis

Inflammation drives many age-related, especially neurological, diseases, and likely mediates age-related proteotoxicity. For example, dementia due to Alzheimer's Disease (AD), cerebral vascular disease, many other neurodegenerative conditions is increasingly among the most devastating burdens on the American (and world) health system and threatens to bankrupt the American health system as the population ages unless effective treatments are developed. Dementia due to either AD or cerebral vascular disease, and plausibly many other neurodegenerative and even psychiatric conditions, is driven by increased age-related inflammation, which in turn appears to mediate Abeta and related proteotoxic processes. The functional significance of inflammation during aging is also supported by the fact that Humira, which is simply an antibody to the pro-inflammatory cytokine TNF-a, is the best-selling drug in the world by revenue. These observations led us to develop parallel high-throughput screens to discover small molecules which inhibit age-related Abeta proteotoxicity in a C. elegans model of AD AND LPS-induced microglial TNF-a. In the initial screen of 2560 compounds (Microsource Spectrum library) to delay Abeta proteotoxicity, the most protective compounds were, in order, phenylbutyrate, methicillin, and quetiapine, which belong to drug classes (HDAC inhibitors, beta lactam antibiotics, and tricyclic antipsychotics, respectably) already robustly implicated as promising to protect in neurodegenerative diseases, especially AD. RNAi and chemical screens indicated that the protective effects of HDAC inhibitors to reduce Abeta proteotoxicity are mediated by inhibition of HDAC2, also implicated in human AD, dependent on the HAT Creb binding protein (Cbp), which is also required for the protective effects of both dietary restriction and the daf-2 mutation (inactivation of IGF-1 signaling) during aging. In addition to methicillin, several other beta lactam antibiotics also delayed Abeta proteotoxicity and reduced microglial TNF-a. In addition to quetiapine, several other tricyclic antipsychotic drugs also delayed age-related Abeta proteotoxicity and increased microglial TNF-a, leading to the synthesis of a novel congener, GM310, which delays Abeta as well as Huntingtin proteotoxicity, inhibits LPS-induced mouse and human microglial and monocyte TNF-a, is highly concentrated in brain after oral delivery with no apparent toxicity, increases lifespan, and produces molecular responses highly similar to those produced by dietary restriction, including induction of Cbp inhibition of inhibitors of Cbp, and genes promoting a shift away from glycolysis and toward metabolism of alternate (e.g., lipid) substrates. GM310, as well as FDA-approved tricyclic congeners, prevented functional impairments and associated increase in TNF-a in a mouse model of stroke. Robust reduction of glycolysis by GM310 was functionally corroborated by flux analysis, and the glycolytic inhibitor 2-DG inhibited microglial TNF-a and other markers of inflammation, delayed Abeta proteotoxicity, and increased lifespan. These results support the value of phenotypic screens to discover drugs to treat age-related, especially neurological and even psychiatric diseases, including AD and stroke, and to clarify novel mechanisms driving neurodegeneration (e.g., increased microglial glycolysis drives neuroinflammation and subsequent neurotoxicity) suggesting novel treatments (selective inhibitors of microglial glycolysis).

Muscle Strength and Biochemical Markers as Predictors of Depression in Hemodialysis Patients: A Cross-Sectional Study

Patients with chronic renal failure, many of which treated with hemodialysis, present a high prevalence of impaired muscle strength which suggest that muscle mass parameters may be used as markers for changes in muscle in these patients. Measurement of handgrip strength (HGS) is a common, simple, and quick measure of muscle function an indicator of overall muscle strength which has been associated with physical activity and several anthropometric traits. Intercellular adhesion molecule-1 (ICAM-1) and insulin-like growth factor-1 (IGF-1) are biochemical markers associated with inflammatory processes which are a common consequence of dialysis. Additionally, hemodialysis patients frequently present signs of malnutrition and depression. This cross-sectional study aimed to evaluate if muscle and biochemical markers could be used to predict the risk of depression in hemodialysis patients. Several anthropometric parameters, nutrient intake, depression state and the serum levels of ICAM-1 and IGF-1 were determined and Pearson's correlation coefficient and/or Spearman's correlation coefficient were used to test the correlation between them. Our results do not show a correlation between HGF, IGF-1 and ICAM-1 with the depression status of the patients, but mid-arm muscle circumference (MAMC) was statistically and positively correlated with depression. Additionally, ICAM-1 levels were negatively correlated with HGS, MAMC, and IGF-1. Overall, the results of the present study suggest that HGS may be used as an indicator of cardiovascular diseases and MAMC may be a good predictor of the level of depression in hemodialysis patients, although further studies are required.

IGF-1 and Risk of Morbidity and Mortality From Cancer, Cardiovascular Diseases, and All Causes in EPIC-Heidelberg

CONTEXT

The functional status of organs, such as the liver, involved in IGF-1 signaling pathways influences circulating levels of IGF-1 and hence its relationship to risk of chronic disease and mortality, yet this has received limited attention.

OBJECTIVE

To examine the relationship between IGF-1 and risk of morbidity and mortality from cancer, cardiovascular diseases (CVD), and all causes, accounting for liver function.

METHODS

This study was a case-cohort design nested within EPIC-Heidelberg. IGF-1 was measured in 7461 stored serum samples collected from 1994 to 1998. Median follow-up for incident mortality events was 17.5 years. The case-cohort included a subcohort of 1810 men and 1890 women, in addition to 1668 incident cases of cancer (623 breast, 577 prostate, 202 lung, and 268 colorectal), and 1428 cases of CVD (707 myocardial infarctions and 723 strokes) and 2441 cases of death.

RESULTS

Higher IGF-1 levels showed direct associations with risks of breast (1.25; 95% CI [1.06-1.47]) and prostate (1.31; [1.09-1.57]) cancers. Restricted cubic splines plots and models including IGF-1 as quintiles revealed a U-shaped relationship between the biomarker and mortality. Participants with the lowest and the highest levels of IGF-1 experienced higher hazards of mortality from cancer, CVD, and all causes. The U-shaped form of the relationship persisted but was attenuated in analyses including only participants without any indications of liver dysfunction.

CONCLUSION

This large population-based prospective study showed that both individuals with lowest and highest levels of circulating IGF-1 were at increased risk of deaths from cancer, CVD, and all causes. For individuals with low IGF-1, the excess risks of death were more pronounced among individuals with liver cancer and cirrhosis but were also present among individuals without elevated liver enzymes.

Insulin-Like Growth Factor 1 and Risk of Cardiovascular Disease: Results From the UK Biobank Cohort Study

CONTEXT

Relationships between insulin-like growth factor 1 (IGF-1) levels and cardiovascular disease (CVD) in the general population remain unclear.

OBJECTIVE

This study aims to investigate the association of circulating IGF-1 concentrations with CVD from a population-based cohort study.

METHODS

A total of 394 082 participants without CVD and cancer at baseline from UK Biobank were included with measurements of serum IGF-1 at baseline. Main outcomes were incidence of CVD, including CVD mortality, coronary heart disease (CHD), myocardial infarction (MI), heart failure (HF), and stroke.

RESULTS

Over a median 11.6 years of follow-up, UK Biobank documented 35 803 incident CVD cases, including 4231 from CVD-related death, 27 051 from CHD, 10 014 from MI, 7661 from HF, and 6802 from stroke. Dose-response analysis showed a U-shaped relationship between IGF-1 levels and cardiovascular events. Compared with the third quintile of IGF-1, the lowest category of IGF-1 was associated with increased risk of CVD (hazard ratio 1.128; 95% CI, 1.093 to 1.164), CVD mortality (1.294; 1.181 to 1.418), CHD (1.118; 1.078 to 1.159), MI (1.071; 1.008 to 1.139), HF (1.185; 1.107 to 1.268), and stroke (1.149, 1.070 to 1.235); also, the highest category was associated with increased risk of CVD (1.056; 1.020 to 1.094), CVD mortality (1.111; 1.000 to 1.236), CHD (1.070; 1.028 to 1.114), MI (1.111; 1.041 to 1.187) and HF (1.098; 1.015 to 1.188) after multivariable adjustment.

CONCLUSION

This study indicates that both low and high levels of circulating IGF-1 are associated with increased risk of CVD in general population. These results highlight the importance of monitoring IGF-1 status on cardiovascular health.

Obese Asthma Phenotype Is Associated with hsa-miR-26a-1-3p and hsa-miR-376a-3p Modulating the IGF Axis

Clarifying inflammatory processes and categorising asthma into phenotypes and endotypes improves asthma management. Obesity worsens severe asthma and reduces quality of life, although its specific molecular impact remains unclear. We previously demonstrated that hsa-miR-26a-1-3p and hsa-miR-376a-3p, biomarkers related to an inflammatory profile, discriminate eosinophilic from non-eosinophilic asthmatics. We aimed to study hsa-miR-26a-1-3p, hsa-miR-376a-3p, and their target genes in asthmatic subjects with or without obesity to find biomarkers and comprehend obese asthma mechanisms. Lung tissue samples were obtained from asthmatic patients (n = 16) and healthy subjects (n = 20). We measured miRNA expression using RT-qPCR and protein levels (IGF axis) by ELISA in confirmation samples from eosinophilic (n = 38) and non-eosinophilic (n = 39) obese (n = 26) and non-obese (n = 51) asthma patients. Asthmatic lungs showed higher hsa-miR-26a-1-3p and hsa-miR-376a-3p expression than healthy lungs. A study of seven genes regulated by these miRNAs revealed differential expression of IGFBP3 between asthma patients and healthy individuals. In obese asthma patients, we found higher hsa-miR-26a-1-3p and IGF-1R values and lower values for hsa-miR-376a-3p and IGFBP-3. Hsa-miR-26a-1-3p and IGFBP-3 were directly and inversely correlated with body mass index, respectively. Hsa-miR-26a-1-3p and hsa-miR-376a-3p could be used as biomarkers to phenotype patients with eosinophilic and non-eosinophilic asthma in relation to comorbid obesity.

Insulin resistance, cognition, and Alzheimer disease

Chronic diseases of aging are increasingly common. Dementia, often due to multiple etiologies including Alzheimer disease (AD), is at the forefront. Previous studies have reported higher rates of dementia among persons with diabetes, yet less is known about how insulin resistance relates to cognition. This article reviews recently published data on the relationship of insulin resistance to cognition and AD, and remaining knowledge gaps in the field are discussed. A structured review of studies was conducted over a 5-year period, investigating insulin and cognitive function in adults with a baseline mean age of ≥65 years. This search yielded 146 articles, of which 26 met the predetermined inclusion and exclusion criteria. Among the nine studies that specifically examined insulin resistance and cognitive dysfunction and/or decline, eight studies suggest an association, but some only in subanalyses. Results are mixed in studies relating insulin to structural and functional changes on brain imaging, and data on intranasal insulin for cognition remain unclear. Future avenues are proposed to elucidate the impact of insulin resistance on brain structure and function, including cognition, in persons with and without AD.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Mechanisms of ageing: growth hormone, dietary restriction, and metformin

Tackling the mechanisms underlying ageing is desirable to help to extend the duration and improve the quality of life. Life extension has been achieved in animal models by suppressing the growth hormone-insulin-like growth factor 1 (IGF-1) axis and also via dietary restriction. Metformin has become the focus of increased interest as a possible anti-ageing drug. There is some overlap in the postulated mechanisms of how these three approaches could produce anti-ageing effects, with convergence on common downstream pathways. In this Review, we draw on evidence from both animal models and human studies to assess the effects of suppression of the growth hormone-IGF-1 axis, dietary restriction, and metformin on ageing.

Cell non-autonomous regulation of cerebrovascular aging processes by the somatotropic axis

Age-related cerebrovascular pathologies, ranging from cerebromicrovascular functional and structural alterations to large vessel atherosclerosis, promote the genesis of vascular cognitive impairment and dementia (VCID) and exacerbate Alzheimer's disease. Recent advances in geroscience, including results from studies on heterochronic parabiosis models, reinforce the hypothesis that cell non-autonomous mechanisms play a key role in regulating cerebrovascular aging processes. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) exert multifaceted vasoprotective effects and production of both hormones is significantly reduced in aging. This brief overview focuses on the role of age-related GH/IGF-1 deficiency in the development of cerebrovascular pathologies and VCID. It explores the mechanistic links among alterations in the somatotropic axis, specific macrovascular and microvascular pathologies (including capillary rarefaction, microhemorrhages, impaired endothelial regulation of cerebral blood flow, disruption of the blood brain barrier, decreased neurovascular coupling, and atherogenesis) and cognitive impairment. Improved understanding of cell non-autonomous mechanisms of vascular aging is crucial to identify targets for intervention to promote cerebrovascular and brain health in older adults.

Hallmarks of aging: An expanding universe

Aging is driven by hallmarks fulfilling the following three premises: (1) their age-associated manifestation, (2) the acceleration of aging by experimentally accentuating them, and (3) the opportunity to decelerate, stop, or reverse aging by therapeutic interventions on them. We propose the following twelve hallmarks of aging: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, disabled macroautophagy, deregulated nutrient-sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. These hallmarks are interconnected among each other, as well as to the recently proposed hallmarks of health, which include organizational features of spatial compartmentalization, maintenance of homeostasis, and adequate responses to stress.

Role of endocrine PACAP in age-related diseases

Pituitary adenylate cyclase activating polypeptide (PACAP) is a conserved neuropeptide, which confers diverse anti-aging endocrine and paracrine/autocrine effects, including anti-apoptotic, anti-inflammatory and antioxidant action. The results of the in vivo and in vitro experiments show that increasing emphasis is being placed on the diagnostic/prognostic biomarker potential of this neuropeptide in a wide array of age-related diseases. After the initial findings regarding the presence and alteration of PACAP in different body fluids in physiological processes, an increasing number of studies have focused on the changes of its levels in various pathological conditions associated with advanced aging. Until 2016 - when the results of previous human studies were reviewed - a vast majority of the studies had dealt with age-related neurological diseases, like cerebrovascular and neurodegenerative diseases, multiple sclerosis, as well as some other common diseases in elderly such as migraine, traumatic brain injury and post-traumatic stress disorder, chronic hepatitis and nephrotic syndrome. The aim of this review is to summarize the old and the new results and highlight those 'classical' and emerging clinical fields in which PACAP may become subject to further investigation as a diagnostic and/or prognostic biomarker in age-related diseases.

Targeting IGF1R signaling for brain aging and Alzheimer's disease

The role of IGF1R signaling in the brain and its relationship to aging and neurological dysfunction is controversial. Because it was shown that low IGF1R activity consistently improved myocardial bioenergetics and function in hearts from aging mice, but not hearts from young mice, it was of interest to investigate this relationship in brain aging. We used CRISPR technology to develop a mouse model with targeted replacement of mouse IGF1R with the equivalent of the human R407H (IGF1RR407H) variant enriched in centenarians with a reduction in IGF1R protein activity. Middle-aged mice show improved cognitive performance thus possibly modeling IGF1R signaling in the aging brain, similar to what was reported in the aging heart. Because Alzheimer's disease (AD) is an age-related disease, specific IGF1RR407H pathways could be therapeutic targets in mice with AAV vector-based AD as well as for overall brain aging.

Diets with higher insulinaemic potential are associated with increased risk of overall and cardiovascular disease-specific mortality

Hyperinsulinaemia and insulin resistance have been proposed to be associated with mortality risk, and diet can modulate insulin response. However, whether dietary patterns with high insulinaemic potential are associated with mortality remains unknown. We prospectively examined the associations between hyperinsulinaemic diets and the risk of total and cause-specific mortality in a large nationally representative population. Dietary factors were assessed by 24-h recalls. Two empirical dietary indices for hyperinsulinaemia (EDIH) and insulin resistance (EDIR) were developed to identify food groups most predictive of biomarkers for hyperinsulinaemia (C-peptide and insulin) and insulin resistance (homoeostatic model assessment for insulin resistance), respectively. Deaths from date of the first dietary interview until 31 December 2015 were identified by the National Death Index. Multivariable hazard ratios (HR) and 95 % CI were calculated using Cox regression models. During a median follow-up of 7·8 years, 4904 deaths were documented among 40 074 participants. For EDIH, the multivariable-adjusted HR (comparing extreme quintiles) were 1·20 (95 % CI 1·09, 1·32, P-trend<0·001) for overall mortality and 1·41 (95 % CI 1·15, 1·74, P-trend = 0·002) for CVD mortality. Similar associations were observed for EDIR with HR of 1·18 (95 % CI 1·07, 1·29, P-trend < 0·001) for total and 1·35 (95 % CI 1·09, 1·67, P-trend = 0·005) for CVD mortality. After further adjustments for BMI and diabetes, these positive associations were somewhat attenuated. Our findings suggested that diets with higher insulinaemic potential are associated with increased risk of overall and CVD-specific mortality.

Lower insulin level is associated with sarcopenia in community-dwelling frail and non-frail older adults

Background

Sarcopenia is common among older individuals with and without type 2 diabetes mellitus (T2DM). There are conflicting evidence in support of the role of insulin in the development of age-related and T2DM-related sarcopenia. We investigated the relationships between the levels of fasting insulin and other blood biomarkers related to insulin or lipid metabolism with the presence of sarcopenia in two independent studies.

Materials and methods

In 246 pre-frail frail older individuals with (n = 41) and without T2DM (n = 205) in the Singapore Frailty Interventional Trial, sarcopenia was defined by low appendicular lean mass (ALM) relative to total body mass (skeletal muscle index, SMI = ALM/height2) and low lower limb strength or gait speed according to the Asian Working Group for Sarcopenia (AWGS) criteria released in 2019, and related to levels of fasting insulin and glucose, C-peptide, IGF-1, leptin, and active ghrelin. This investigation was validated in another independent study sample of 189 robust and pre-frail frail elderly in the Singapore Longitudinal Aging Study Wave 2 (SLAS-2).

Results

Compared to non-sarcopenic individuals, those with sarcopenia and possible sarcopenia showed significantly lower fasting insulin (p < 0.05) in pre-frail/frail and non-frail older individuals. Consistent trends of relationships were observed for serum levels of C-peptide, IGF-1, leptin, and active ghrelin. In multivariable logistic regression models, sarcopenia was independently associated with low insulin (p < 0.05). Levels of fasting insulin, C-peptide, and leptin were also significantly associated with BMI, SMI, knee extension strength, gait speed, and physical activity score.

Conclusion

Dysregulated insulin secretion in diabetic and non-diabetic older individuals may play an important role in age-related and diabetes-related sarcopenia.

Decreased lifespan in female "Munchkin" actors from the cast of the 1939 film version of The Wizard of Oz does not support the hypothesis linking hypopituitary dwarfism to longevity

In laboratory mice, pituitary dwarfism caused by genetic reduction or elimination of the activity of growth hormone (GH) significantly extends lifespan. The effects of congenital pituitary dwarfism on human longevity are not well documented. To analyse the effects of untreated pituitary dwarfism on human lifespan, the longevity of a diverse group of widely known little people, the 124 adults who played "Munchkins" in the 1939 movie The Wizard of Oz was investigated. Survival of "Munchkin" actors with those of controls defined as cast members of The Wizard of Oz and those of other contemporary Academy Award winning Hollywood movies was compared. According to the Kaplan-Meier survival curves, survival of female and male "Munchkin" actors was shorter than cast controls and Hollywood controls of respective sexes. Cox regression analyses showed that female "Munchkin" actors had significantly higher risk ratios compared to both female cast controls (RR, 1.70; 95% CI, 1.05 to 2.77) and female Hollywood controls (RR, 1.52; 95% CI, 1.03 to 2.24). Similar trends were also discernible for men, albeit point estimates were not significant. The lack of lifespan extension in "Munchkin" actors does not support the hypothesis that hereditary GH deficiency regulates longevity in humans.

Association of dietary inflammatory potential with risk of overall and cause-specific mortality

Inflammation is a central mechanism in metabolic disorders associated with morbidity and mortality and dietary factors can modulate inflammation. We aimed to prospectively investigate the association between an empirically developed, food-based dietary inflammatory pattern (EDIP) score and the risk of overall and cause-specific mortality, using data from the US National Health and Nutrition Examination Survey from 1999 to 2014. EDIP score was derived by entering thirty-nine predefined commonly consumed food groups into the reduced rank regression models followed by stepwise linear regression, which was most predictive of two plasma inflammation biomarkers including C-reactive protein and leucocyte count among 25 500 US adults. This score was further validated in a testing set of 9466 adults. Deaths from baseline until 31 December 2015 were identified through record linkage to the National Death Index. During a median follow-up of 7·8 years among 40 074 participants, we documented 4904 deaths. Compared with participants in the lowest quintile of EDIP score, those in the highest quintile had a higher risk of overall death (hazard ratio (HR) = 1·19, 95 % CI 1·08, 1·32, P_trend = 0·002), and deaths from cancer (HR = 1·41, 95 % CI 1·14, 1·74, P_trend = 0·017) and CVD (HR = 1·22, 95 % CI 0·98, 1·53, P_trend = 0·211). When stratified by age, the association of EDIP with overall mortality was stronger among individuals under 65 years of age (P_interaction = 0·001). Diets with a higher inflammatory potential were associated with increased risk of overall and cancer-specific mortality. Interventions to reduce the adverse effect of pro-inflammatory diets may potentially promote health and longevity.

Relative Trajectories of Gait and Cognitive Decline in Aging

BACKGROUND

Gait and cognition decline with advancing age, and presage the onset of dementia. Yet, the relative trajectories of gait and cognitive decline in aging are poorly understood-particularly among those with the motoric cognitive risk (MCR) syndrome. This study compared changes in simple and complex gait performance and cognition, as a function of age and MCR.

METHODS

We examined gait and cognitive functions of 1 095 LonGenity study participants (mean age = 75.4 ± 6.7 years) with up to 12 years of annual follow-up. Participants were of Ashkenazi Jewish descent, free of dementia, ambulatory, and had a 12.2% MCR prevalence at baseline. Gait speed was measured at usual pace walking (single-task walking, STW-speed) and walking while talking (WWT-speed). Eleven neuropsychological test scores were examined separately, and as a global cognition composite. Linear mixed-effects models adjusted for baseline sex, education, parental longevity, cognitive impairment, and global health were used to estimate changes in gait and cognition, as a function of age and MCR.

RESULTS

STW-speed, WWT-speed, and cognitive tests performance declined in a nonlinear (accelerating) fashion with age. STW-speed declined faster than WWT-speed and cognitive test scores. People with MCR showed faster rates of decline on figure copy and phonemic fluency.

CONCLUSIONS

Gait declines at a faster rate than cognition in aging. People with MCR are susceptible to faster decline in visuospatial, executive, and language functions. This study adds important knowledge of trajectories of gait and cognitive decline in aging, and identifies MCR as a risk factor for accelerated cognitive decline.

Physiological Systems in Promoting Frailty

Frailty is a complex syndrome affecting a growing sector of the global population as medical developments have advanced human mortality rates across the world. Our current understanding of frailty is derived from studies conducted in the laboratory as well as the clinic, which have generated largely phenotypic information. Far fewer studies have uncovered biological underpinnings driving the onset and progression of frailty, but the stage is set to advance the field with preclinical and clinical assessment tools, multiomics approaches together with physiological and biochemical methodologies. In this article, we provide comprehensive coverage of topics regarding frailty assessment, preclinical models, interventions, and challenges as well as clinical frameworks and prevalence. We also identify central biological mechanisms that may be at play including mitochondrial dysfunction, epigenetic alterations, and oxidative stress that in turn, affect metabolism, stress responses, and endocrine and neuromuscular systems. We review the role of metabolic syndrome, insulin resistance and visceral obesity, focusing on glucose homeostasis, adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and nicotinamide adenine dinucleotide (NAD+ ) as critical players influencing the age-related loss of health. We further focus on how immunometabolic dysfunction associates with oxidative stress in promoting sarcopenia, a key contributor to slowness, weakness, and fatigue. We explore the biological mechanisms involved in stem cell exhaustion that affect regeneration and may contribute to the frailty-associated decline in resilience and adaptation to stress. Together, an overview of the interplay of aging biology with genetic, lifestyle, and environmental factors that contribute to frailty, as well as potential therapeutic targets to lower risk and slow the progression of ongoing disease is covered. © 2022 American Physiological Society. Compr Physiol 12:1-46, 2022.

Declining Levels and Bioavailability of IGF-I in Cardiovascular Aging Associate With QT Prolongation-Results From the 1946 British Birth Cohort

Background

As people age, circulating levels of insulin-like growth factors (IGFs) and IGF binding protein 3 (IGFBP-3) decline. In rat cardiomyocytes, IGF-I has been shown to regulate sarcolemmal potassium channel activity and late sodium current thus impacting cardiac repolarization and the heart rate-corrected QT (QTc). However, the relationship between IGFs and IGFBP-3 with the QTc interval in humans, is unknown.

Objectives

To examine the association of IGFs and IGFBP-3 with QTc interval in an older age population-based cohort.

Methods

Participants were from the 1946 Medical Research Council (MRC) National Survey of Health and Development (NSHD) British birth cohort. Biomarkers from blood samples at age 53 and 60-64 years (y, exposures) included IGF-I/II, IGFBP-3, IGF-I/IGFBP-3 ratio and the change (Δ) in marker levels between the 60-64 and 53y sampled timepoints. QTc (outcome) was recorded from electrocardiograms at the 60-64y timepoint. Generalized linear multivariable models with adjustments for relevant demographic and clinical factors, were used for complete-cases and repeated after multiple imputation.

Results

One thousand four hundred forty-eight participants were included (48.3% men; QTc mean 414 ms interquartile range 26 ms). Univariate analysis revealed an association between low IGF-I and IGF-I/IGFBP-3 ratio at 60-64y with QTc prolongation [respectively: β -0.30 ms/nmol/L, (95% confidence intervals -0.44, -0.17), p < 0.001; β-28.9 ms/unit (-41.93, -15.50), p < 0.001], but not with IGF-II or IGFBP-3. No association with QTc was found for IGF biomarkers sampled at 53y, however both ΔIGF-I and ΔIGF-I/IGFBP-3 ratio were negatively associated with QTc [β -0.04 ms/nmol/L (-0.08, -0.008), p = 0.019; β -2.44 ms/unit (-4.17, -0.67), p = 0.007] while ΔIGF-II and ΔIGFBP-3 showed no association. In fully adjusted complete case and imputed models (reporting latter) low IGF-I and IGF-I/IGFBP-3 ratio at 60-64y [β -0.21 ms/nmol/L (-0.39, -0.04), p = 0.017; β -20.14 ms/unit (-36.28, -3.99), p = 0.015], steeper decline in ΔIGF-I [β -0.05 ms/nmol/L/10 years (-0.10, -0.002), p = 0.042] and shallower rise in ΔIGF-I/IGFBP-3 ratio over a decade [β -2.16 ms/unit/10 years (-4.23, -0.09), p = 0.041], were all independently associated with QTc prolongation. Independent associations with QTc were also confirmed for other previously known covariates: female sex [β 9.65 ms (6.65, 12.65), p < 0.001], increased left ventricular mass [β 0.04 ms/g (0.02, 0.06), p < 0.001] and blood potassium levels [β -5.70 ms/mmol/L (-10.23, -1.18) p = 0.014].

Conclusion

Over a decade, in an older age population-based cohort, declining levels and bioavailability of IGF-I associate with prolongation of the QTc interval. As QTc prolongation associates with increased risk for sudden death even in apparently healthy people, further research into the antiarrhythmic effects of IGF-I on cardiomyocytes is warranted.

Role of circulating molecules in age-related cardiovascular and metabolic disorders

Studies analyzing heterochronic parabiosis mice models showed that molecules in the blood of young mice rejuvenate aged mice. Therefore, blood-based therapies have become one of the therapeutic approaches to be considered for age-related diseases. Blood includes numerous biologically active molecules such as proteins, metabolites, hormones, miRNAs, etc. and accumulating evidence indicates some of these change their concentration with chronological aging or age-related disorders. The level of some circulating molecules showed a negative or positive correlation with all-cause mortality, cardiovascular events, or metabolic disorders. Through analyses of clinical/translation/basic research, some molecules were focused on as therapeutic targets. One approach is the supplementation of circulating anti-aging molecules. Favorable results in preclinical studies let some molecules to be tested in humans. These showed beneficial or neutral results, and some were inconsistent. Studies with rodents and humans indicate circulating molecules can be recognized as biomarkers or therapeutic targets mediating their pro-aging or anti-aging effects. Characterization of these molecules with aging, testing their biological effects, and finding mimetics of young systemic milieu continue to be an interesting and important research topic to be explored.

Extending human healthspan and longevity: a symposium report

For many years, it was believed that the aging process was inevitable and that age-related diseases could not be prevented or reversed. The geroscience hypothesis, however, posits that aging is, in fact, malleable and, by targeting the hallmarks of biological aging, it is indeed possible to alleviate age-related diseases and dysfunction and extend longevity. This field of geroscience thus aims to prevent the development of multiple disorders with age, thereby extending healthspan, with the reduction of morbidity toward the end of life. Experts in the field have made remarkable advancements in understanding the mechanisms underlying biological aging and identified ways to target aging pathways using both novel agents and repurposed therapies. While geroscience researchers currently face significant barriers in bringing therapies through clinical development, proof-of-concept studies, as well as early-stage clinical trials, are underway to assess the feasibility of drug evaluation and lay a regulatory foundation for future FDA approvals in the future.

The antagonistic pleiotropy of insulin-like growth factor 1

While insulin-like growth factor-1 (IGF-1) is a well-established modulator of aging and longevity in model organisms, its role in humans has been controversial. In this study, we used the UK Biobank (n = 440,185) to resolve previous ambiguities in the relationship between serum IGF-1 levels and clinical disease. We examined prospective associations of serum IGF-1 with mortality, dementia, vascular disease, diabetes, osteoporosis, and cancer, finding two generalized patterns: First, IGF-1 interacts with age to modify risk in a manner consistent with antagonistic pleiotropy; younger individuals with high IGF-1 are protected from disease, while older individuals with high IGF-1 are at increased risk for incident disease or death. Second, the association between IGF-1 and risk is generally U-shaped, indicating that both high and low levels of IGF-1 may be detrimental. With the exception of a more uniformly positive relationship between IGF-1 and cancer, these effects were remarkably consistent across a wide range of conditions, providing evidence for a unifying pathway that determines risk for most age-associated diseases. These data suggest that IGF-1 signaling could be harmful in older adults, who may actually benefit from the attenuation of biological growth pathways.

Einstein-Nathan Shock Center: translating the hallmarks of aging to extend human health span

The overarching mission of the Einstein-Nathan Shock Center (E-NSC) is to make scientific discoveries in geroscience, leveraging on the expertise in our center in 6 out of the 7 pillars of aging, and to translate their effects towards drug discovery. The relevance of this basic biology of aging discoveries to humans will be confirmed through the unique gero-human resource at E-NSC. This is achieved through services provided by E-NSC, connectivity among its members, attracting worldwide investigators, and providing them with the opportunities to become future leaders. The two central components of the E-NSC are (a) cutting-edge research programs and (b) unique E-NSC research support cores. E-NSC scientists lead NIH-supported cutting-edge research programs that integrate key hallmarks of aging including proteostasis/autophagy, metabolism/inflammaging, genetic/epigenetics, stem cells/regeneration, and translational aging/longevity. Since the inception of the E-NSC, the well-integrated, collaborative, and innovative nature of the multiple supporting state-of-the-art E-NSC research cores form the bedrock of research success at the E-NSC. The three state-of-the-art E-NSC research cores, (i) Proteostasis of Aging Core (PAC), (ii) the Health Span Core (HSC), and (iii) the Human Multi-Omics Core (HMOC), have allowed impressive expansion of translational biological research programs. Expansion was facilitated through the wealth of data coming from genomics/proteomics and metabolomic analysis on human longevity studies, due to access to a variety of biological samples from elderly subjects in clinical trials with aging-targeting drugs, and new drug design services via the PAC to target the hallmarks of aging.

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

Effect of longevity genetic variants on the molecular aging rate

We conducted a genome-wide association study of 1320 centenarians from the New England Centenarian Study (median age = 104 years) and 2899 unrelated controls using >9 M genetic variants imputed to the HRC panel of ~65,000 haplotypes. The genetic variants with the most significant associations were correlated to 4131 proteins that were profiled in the serum of a subset of 224 study participants using a SOMAscan array. The genetic associations were replicated in a genome-wide association study of 480 centenarians and ~800 controls of Ashkenazi Jewish descent. The proteomic associations were replicated in a proteomic scan of approximately 1000 Ashkenazi Jewish participants from a third cohort. The analysis replicated a protein signature associated with APOE genotypes and confirmed strong overexpression of BIRC2 (p < 5E-16) and under-expression of APOB in carriers of the APOE2 allele (p < 0.05). The analysis also discovered and replicated associations between longevity variants and slower changes of protein biomarkers of aging, including a novel protein signature of rs2184061 (CDKN2A/CDKN2B in chromosome 9) that suggests a genetic regulation of GDF15. The analyses showed that longevity variants correlate with proteome signatures that could be manipulated to discover healthy-aging targets.

Can Blood-Circulating Factors Unveil and Delay Your Biological Aging?

According to the World Health Organization, the population of over 60 will double in the next 30 years in the developed countries, which will enforce a further raise of the retirement age and increase the burden on the healthcare system. Therefore, there is an acute issue of maintaining health and prolonging active working longevity, as well as implementation of early monitoring and prevention of premature aging and age-related disorders to avoid early disability. Traditional indicators of biological age are not always informative and often require extensive and expensive analysis. The study of blood factors is a simple and easily accessible way to assess individual health and supplement the traditional indicators of a person's biological age with new objective criteria. With age, the processes of growth and development, tissue regeneration and repair decline; they are gradually replaced by enhanced catabolism, inflammatory cell activity, and insulin resistance. The number of senescent cells supporting the inflammatory loop rises; cellular clearance by autophagy and mitophagy slows down, resulting in mitochondrial and cellular damage and dysfunction. Monitoring of circulated blood factors not only reflects these processes, but also allows suggesting medical intervention to prevent or decelerate the development of age-related diseases. We review the age-related blood factors discussed in recent publications, as well as approaches to slowing aging for healthy and active longevity.

Relationship Between Serum IGF-1 and BMI Differs by Age

BACKGROUND

Serum levels of insulin-like growth factor 1 (IGF-1) and body mass index (BMI) are both associated with susceptibility to age-related diseases. Reports on the correlation between them have been conflicting, with both positive to negative correlations reported. However, the age ranges of the participants varied widely among these studies.

METHODS

Using data on 4241 participants (aged 24-110) from the Long Life Family Study, we investigated the relationship between IGF-1 and BMI by age groups using regression analysis.

RESULTS

When stratified by age quartile, the relationship between IGF-1 and BMI varied: in the first quartile (Q1, 20-58 years) the relationship was negative (β = -0.2, p = .002); in Q2 (58-66 years) and Q3 (67-86 years) the relationship was negative (β = -0.07, β = -0.01, respectively) but nonsignificant; and in Q4 (87-110 years) the relationship was positive (β = 0.31, p = .0002). This pattern did not differ by sex. We observed a similar age-related pattern between IGF-1 and BMI among participants in the third National Health and Nutritional Examination Survey.

CONCLUSIONS

Our results that the relationship between IGF-1 and BMI differs by age may explain some of the inconsistency in reports about their relationship and encourage additional studies to understand the mechanisms underlying it.

Blood-based biomarkers in hypothalamic-pituitary axes for the risk of dementia or cognitive decline: a systematic review and meta-analysis

Blood-based biomarkers are ideal candidates for dementia prediction. This systematic review and meta-analysis aimed to evaluate longitudinal relationships of blood hormones and hormone-binding proteins in hypothalamic-pituitary (HP) axes with dementia or cognitive decline. PubMed, MEDLINE, EMBASE, PsycINFO, and BIOSIS were systematically searched from 1919 to June 2020. Fifteen types of hormones and four types of hormone-binding proteins were measured in 48 prospective studies. Increased risk of dementia or cognitive decline could be predicted by elevated blood concentrations of free-thyroxine (free-T4, RR = 1.06, p = 0.001) and sex hormone-binding globulin (SHBG, RR = 1.10, p = 0.025). Lower thyroid-stimulating hormone (TSH) levels within (RR = 1.28, p < 0.001) and below (RR = 1.27, p = 0.004) the normal range were both risky. Current evidence suggests the alterations of multiple blood molecules in HP axes, especially TSH, free-T4, and SHBG precede the incidence of dementia or cognitive decline. The underpinning etiology remains to be elucidated in the future.

Insulin-Like Growth Factors in Development, Cancers and Aging

Since their discovery in the late 1950s, insulin-like growth factors (IGFs) have attracted significant interest in multiple areas of biology and medicine, including endocrinology, pediatrics, growth, metabolism, nutrition, aging, and oncology [...].