Aging

Temporally controlling cre recombination through tamoxifen (Tam) induction has many advantages for biomedical research. Most studies report Tam induction at early post-natal/juvenile (<2 m.o.) mouse ages, but age-related neurodegeneration and aging studies can require cre induction in older mice (>12 m.o.). While anecdotally reported as problematic, there are no published comparisons of Tam mediated cre induction at early and late ages. Here, microglial-specific Cx3cr1creERT2 mice were crossed to a floxed NuTRAP reporter to compare cre induction at early (3-6 m.o.) and late (20 m.o.) ages. Specificity and efficiency of microglial labeling at 21-22 m.o. were identical in mice induced with Tam at 3-6 m.o. or 20 m.o. of age. Age-related microglial translatomic changes were also similar regardless of Tam induction age. Each cre and flox mouse line should be validated independently, however, these findings demonstrate that Tam-mediated cre induction can be performed even into older mouse ages.

Aging-related decline in immune function is associated with diseases like cancer, atherosclerosis, and neurodegenerative conditions. This study aimed to improve the aging gut microbiota and immune system by introducing a prebiotic oligosaccharide, 2-fucosyllactose (2-FL), abundant in human breast milk with established health benefits in infants and animal models. 2-FL was consumed at either of two doses versus placebo by 89 healthy older individuals (average age = 67.3 years) in a 6-week randomized controlled trial. Although the primary endpoint (significant change in the cytokine response score) was not met, consumers of the prebiotic experienced increased levels of Bifidobacterium in the gut microbiota, along with elevated serum levels of insulin, high-density lipoprotein (HDL) cholesterol, and fibroblast growth factor 21 (FGF21) hormone. Multi-omics analysis indicated a systemic response to 2-FL, which could be detected in blood and urine, showcasing the potential of this prebiotic to provide diverse benefits to aging individuals.

BackgroundCompared to cancer-free persons, cancer survivors of the same chronological age (CA) have increased physiological dysfunction, i.e., higher biological age (BA), which may lead to higher morbidity and mortality. We estimated BA using eight aging metrics: BA computed by Klemera Doubal method (KDM-BA), phenotypic age (PhenoAge), five epigenetic clocks (ECs, Horvath, Hannum, Levine, GrimAge, and pace of aging (POA)), and subjective age (SA). We tested if aging constructs were associated with total cancer prevalence and all-cause mortality in cancer survivors and controls, i.e., cancer-free persons, in the Health and Retirement Study (HRS), a large population-based study. MethodsIn 2016, data on BA-KDM, PhenoAge, and SA were available for 946 cancer survivors and 4,555 controls; data for the five ECs were available for 582 cancer survivors and 2,805 controls. Weighted logistic regression was used to estimate the association between each aging construct and cancer prevalence (odds ratio, OR, 95%CI). Weighted Cox proportional hazards regression was used to estimate the associations between each aging construct and cancer incidence as well as all-cause mortality (hazard ratio, HR, 95%CI). To study all BA metrics (except for POA) independent of CA, we estimated age acceleration as residuals of BA regressed on CA. ResultsAge acceleration for each aging construct and POA were higher in cancer survivors than controls. In a multivariable-adjusted model, five aging constructs (age acceleration for Hannum, Horvath, Levine, GrimAge, and SA) were associated with cancer prevalence. Among all cancer survivors, age acceleration for PhenoAge and four ECs (Hannum, Horvath, Levine, and GrimAge), was associated with higher all-cause mortality over 4 years of follow-up. PhenoAge, Hannum, and GrimAge were also associated with all-cause mortality in controls. The highest HR was observed for GrimAge acceleration in cancer survivors: 2.03 (95% CI, 1.58-2.60). In contrast, acceleration for KDM-BA and POA was significantly associated with mortality in controls but not in cancer survivors. When all eight aging constructs were included in the same model, two of them (Levine and GrimAge) were significantly associated with mortality among cancers survivors. None of the aging constructs were associated with cancer incidence. ConclusionVariations in the associations between aging constructs and mortality in cancer survivors and controls suggests that aging constructs may capture different aspects of aging and that cancer survivors may be experiencing age-related physiologic dysfunctions differently than controls. Future work should evaluate how these aging constructs predict mortality for specific cancer types.

Aging interventions have progressed in recent years due to the growing curiosity about how lifestyle impacts longevity. This study assessed the effects of SRW Laboratories Cel System nutraceutical range on epigenetic methylation patterns, inflammation, physical performance, body composition, and epigenetic biomarkers of aging. A 1-year study was conducted with 51 individuals, collecting data at baseline, 3 months, 6 months, and 12 months. Participants were encouraged to walk 10 minutes and practice 5 minutes of mindfulness daily. Significant improvements in muscle strength, body function, and body composition metrics were observed. Epigenetic clock analysis showed a decrease in biological age with significant reductions in stem cell division rates. Immune cell subset analysis indicated significant changes, with increases in eosinophils and CD8T cells and decreases in B memory, CD4T memory, and T-regulatory cells. Predicted epigenetic biomarker proxies (EBPs) showed significant changes in retinol/TTHY, a regulator of cell growth, proliferation, and differentiation, and deoxycholic acid glucuronide levels, a metabolite of deoxycholic acid generated in the liver. Gene ontology analysis revealed significant CpG methylation changes in genes involved in critical biological processes related to aging, such as oxidative stress-induced premature senescence, pyrimidine deoxyribonucleotide metabolic process, TRAIL binding, hyaluronan biosynthetic process, neurotransmitter loading into synaptic vesicles, pore complex assembly, collagen biosynthetic process, protein phosphatase 2A binding activity, and activation of transcription factor binding. Our findings suggest that the Cel System supplement range may effectively reduce biological age and improve health metrics, warranting further investigation into its mechanistic pathways and long-term efficacy.

BackgroundDIMT1 is a highly conserved methyltransferase that functions as an N6,N6-dimethyladenosine transferase responsible for modifying two adjacent adenosines in the 18S rRNA. This protein is also a crucial, yet catalytically independent, ribosome maturation factor essential for the biogenesis of the 40S small ribosomal subunit. Given the established roles of ribosome biogenesis and methylation dynamics in biological aging, we investigated the relationship between DIMT1 expression and chronological donor age in Mesenchymal Stromal Cells (MSCs). MethodsTranscriptomic data for DIMT1 from a publicly available human MSC dataset (n = 61 donors, age range: 17-84 years) were analyzed. Pearson correlation and simple linear regression were performed to assess the association between normalized gene expression and donor age. ResultsA statistically significant positive correlation was identified between DIMT1 expression and donor age (Pearson r = 0.4282, R2 = 0.183, p = 0.0006). Linear regression modeling demonstrated that expression increases with advancing age, exhibiting a slope of 0.0045. ConclusionDIMT1 expression demonstrates a statistically significant positive correlation with donor age in MSCs, though age explains only 18.3% of expression variance. This relationship warrants further investigation of DIMT1 as a component of multi-gene aging signatures. The observed pattern may reflect compensatory responses in ribosome biogenesis or altered methylation dynamics associated with aging, though mechanistic validation is required.

Sepsis can lead to acute respiratory distress syndrome (ARDS) and is associated with a high mortality rate. This study investigated cellular senescence-related genes in sepsis and sepsis-induced ARDS to identify novel biomarkers. Using bioinformatics analyses including WGCNA and machine learning on public datasets, six hub genes (NFIL3, GARS, PIGM, DHRS4L2, CLIP4, LY86) were identified. These genes showed strong diagnostic value and were associated with immune cell infiltration and key pathways. Validation in lipopolysaccharide (LPS)-stimulated neutrophils showed significant upregulation of NFIL3. The findings highlight the role of cellular senescence in pathogenesis and identify promising therapeutic targets for sepsis-induced ARDS.

ObjectiveRecently, we demonstrated cholesterol accelerating colorectal cancer (CRC) progression via squalene epoxidase (SQLE) reduction, activating the {beta}-catenin oncogenic pathway while downregulating the p53 pathway, mediated by the inhibition of GSK3{beta} activity (GSK3{beta}pS9). However, the interrelationship between cholesterol increase and CRC progression with aging has never been determined. DesignWe utilized case data from public databases and human specimens to assess the relationship between cholesterol accumulation and CRC progression with aging. Digital image analysis-machine learning with multiplex fluorescence-immunohistochemistry evaluated the effects of SQLE, p53WT, p53MT, and GSK3{beta}pS9 (hereafter candidates) on the survival of CRC patients. Also, the prognostic and diagnostic abilities were assessed by a time-dependent receiver operating characteristic (timeROC) and a ROC curve with and without the discriminant score for the candidates as a single or whole, respectively. ResultsWe found an accumulation of cholesterol and cholesteryl ester in tissues with aging, which led to the acceleration of CRC progression through substantial decreases of SQLE, p53WT, p53MT expressions and inhibition of GSK3{beta} activity in advanced CRCs. Retrospective studies demonstrated that SQLE significantly impacted the shortened progression-free survival of the population with progressive pathological severity and high CRC risk beyond the age of 50. Clinical assays further showed the excellent prognostic and diagnostic abilities of SQLE and GSK3{beta}pS9 but also the substantial diagnostic potential of the combined candidate for the aged high-risk CRC population. ConclusionWe provide new insights into the relationship between cholesterol increase and CRC progression with aging and identify valuable biomarkers for aged populations with high-risk CRC.

Motor and cognitive aging can severely affect life quality of elderly people and burden health care systems. In search for diagnostic behavioral biomarkers, it has been suggested that walking speed can predict forms of cognitive decline, but in humans, it remains challenging to separate the effects of biological aging and lifestyle. We examined a possible association of motor and cognitive decline in Drosophila, a genetic model organism of healthy aging. Long term courtship memory is present in young flies but absent already during mid life (4-8 weeks). By contrast, courtship learning index and short term memory (STM) are surprisingly robust and remain stable through mid (4-8 weeks) and healthy late life (>8 weeks), until courtship performance collapses suddenly at [~]4.5 days prior to death. By contrast, climbing speed declines gradually during late life (>8 weeks). The collapse of courtship performance and short term memory close to the end of life are not related to the gradual late life decline in climbing speed. Thus, during healthy aging in Drosophila, climbing and courtship motor behaviors decline differentially, unlikely share a common cause, and motor and cognitive performance decline are not closely associated to each other.

Pharmacological interventions targeting the aging process hold significant promise for improving the quality of life in the elderly and reducing healthcare costs. Rapamycin, in particular, has exhibited significant anti-aging and lifespan-extending effects across multiple model organisms. However, chronic rapamycin administration may also lead to various adverse reactions since it reshapes energy metabolism. Here, using Drosophila melanogaster as a model, we show that life-prolonging doses of rapamycin significantly modify animal feeding behavior. Long-term administration of rapamycin decreased protein preference in females while enhancing their sugar intake. Utilizing a chemically defined diet, we identified that changes in amino acid and sugar feeding preferences emerged as early as the second day of rapamycin treatment, preceding any detectable decline in fecundity. However, rapamycin-induced changes in macronutrient feeding preferences were not observed in males and sterile mutant females. Overall, our study suggests that the modification of feeding behavior could be a non-negligible side effect of rapamycin treatment, which is influenced by both sex and reproductive status.

Cellular senescence and DNA methylation are primary aging mechanisms emerging as a potential means of monitoring human aging and evaluating interventions thought to either accelerate or slow an individuals aging trajectory. However, it is largely unknown whether cellular senescence and signatures of methylation of the specific CpG islands that comprise various epigenetic clocks correlate in humans. We have measured the cellular senescence biomarker, p16 and the five most used epigenetic aging clocks in 251 patients with breast cancer, 49 age-matched non-cancer controls, and 48 patients undergoing cytotoxic chemotherapy treatment. Chemotherapy, a known clinically-relevant inducer of aging, increased expression of p16 but not levels of the most common epigenetic clocks (DNAm-Horvath, PhenoAge, GrimAge, mPoA), with the exception of DNAm-Hannum. Chemotherapy-induced changes in p16 were associated with increased levels of a subset of SASPs, PARC, TNFRII, ICAM1, and TNFa. Cross-sectionally, there was weak to no correlation between p16 expression and epigenetic clocks in cancer patients or non-cancer controls. GrimAge and PhenoAge were the most correlated with p16 (r<0.3), with no correlation between p16 and the pace of aging epigenetic clock. Together, these data show that there is a general discordance between measures of cellular senescence and epigenetic clocks with the senescence marker p16 but not epigenetic clocks of aging responding to a clinically relevant inducer of human aging, cytotoxic chemotherapy.

MicroRNAs (miRNAs) have been demonstrated to modulate life span in the invertebrates C. elegans and Drosophila by targeting conserved pathways of aging, such as insulin/IGF-1 signaling (IIS). However, a role for miRNAs in modulating human longevity has not been fully explored. Here we investigated novel roles of miRNAs as a major epigenetic component of exceptional longevity in humans. By profiling the miRNAs in B-cells from Ashkenazi Jewish centenarians and 70-year-old controls without a longevity history, we found that the majority of differentially expressed miRNAs were upregulated in centenarians and predicted to modulate the IIS pathway. Notably, decreased IIS activity was found in B cells from centenarians who harbored these upregulated miRNAs. miR-142-3p, the top upregulated miRNA, was verified to dampen the IIS pathway by targeting multiple genes including GNB2, AKT1S1, RHEB and FURIN. Overexpression of miR-142-3p improved the stress resistance under genotoxicity and induced the impairment of cell cycle progression in IMR90 cells. Furthermore, mice injected with a miR-142-3p mimic showed reduced IIS signaling and improved longevity-associated phenotypes including enhanced stress resistance, improved diet/aging-induced glucose intolerance, and longevity-associated change of metabolic profile. These data suggest that miR-142-3p is involved in human longevity through regulating IIS-mediated pro-longevity effects. This study provides strong support for the use of miR-142-3p as a novel therapeutic to promote longevity or prevent aging/aging-related diseases in human.

BackgroundPhosphatidylinositol transfer protein-1 (pitp-1) is involved in phosphoinositide turnover. The role of pitp-1 in promoting healthy longevity remains unknown. Our previous work showed that the phosphoinositide turnover genes dagl-1 and dgk-5 regulates lifespan, as overexpression of dagl-1 or knockdown of dgk-5 prolongs lifespan and enhances oxidative stress resistance through TOR signaling. As pitp-1 is a key component of this pathway, we investigated its role in lifespan regulation and the underlying mechanisms, aiming to clarify whether it represents a critical regulator of healthy longevity and how it coordinates conserved signaling pathways to regulate aging. MethodsC. elegans mutants, RNAi-mediated knockdown, and transgenic overexpression were applied to assess lifespan, motility, stress resistance. Temporal and tissue-specific RNAi were applied to identify the critical time window and tissue for pitp-1-mediated lifespan regulation. TOR signaling was measured by phosphorylated S6 kinase and puromycin incorporation, and transcriptomic analysis identified affected pathways. Resultspitp-1 negatively regulates lifespan and healthspan in Caenorhabditis elegans. Genetic deletion or RNAi-mediated knockdown of pitp-1 extends lifespan, attenuates age-related motility decline, and increases oxidative stress resistance. Temporal and spatial analyses reveal that suppression of pitp-1 in neurons during early adulthood is sufficient to promote healthy longevity. Mechanistically, these beneficial effects upon pitp-1 reduction are mediated by suppressing TOR signaling. Conversely, pitp-1 overexpression shortens lifespan and impairs healthspan via TOR activation. Moreover, pitp-1 is transcriptionally repressed by DAF-16 downstream of insulin/IGF-1 signaling (IIS), and contributes to IIS-mediated lifespan extension. ConclusionThese findings identify pitp-1 as a novel regulator of healthy aging that integrates IIS and TOR pathways, providing new insights into conserved mechanisms for promoting healthy longevity.

Cellular senescence is a key mechanism of skeletal aging in both physiological and accelerated conditions, such as radiotherapy. This study aimed to identify common differentially regulated microRNAs (miRs) across these contexts. We performed miR sequencing on three models: femurs from young (5-month-old) versus old (24-month-old) mice; focally radiated versus non-radiated femurs; and osteocytes from young versus old mice. Osteocytes were included in the comparison, as they have the longest lifespan in the mineralized bone matrix and they form 90-95% of all mesenchymal bone cell types. Among the three groups, miR-135a-5p and miR-671-5p were the common (i.e., shared) miRs that were downregulated, and miR-183-5p, a miR that regulates the WNT pathway, was the only shared upregulated miR, while miR-155-5p, a miR that regulates the Senescence-Associated Secretory Phenotype (SASP), was elevated in two conditions. The WNT-pathway has been positively associated with bone health and Sclerostin, a WNT-pathway inhibitor produced and secreted by osteocytes, has been implicated in accelerated skeletal deterioration following radiation. Thus, we used a neutralizing antibody to Sclerostin (Scl-Ab), to assess genes related to the WNT pathway and senescence, which are regulated by miR-183-5p and miR-155-5p, respectively. We further performed miR sequencing in radiated bones from mice treated with Scl-Ab and identified miR-133a-3p, a key miR that inhibits bone metabolism and function, which is upregulated in accelerated skeletal aging (i.e., focal radiation) downregulated by Scl-Ab. Overall, our study identifies potential regulatory gene pathways that modulate skeletal aging in the presence and absence of a WNT activator, Scl-Ab.

Aging clocks have emerged as the primary tools for measuring biological aging and have been developed for a wide range of single-omic measurements. Epigenetic aging clocks showed high accuracy in age prediction, however, their biological interpretation is still a challenging task. Transcriptomics aging clocks provide better interpretability but worse age prediction accuracy. To exploit the benefits of both omics techniques, the main goal of this study was to develop the first multi-omics aging clocks based on combined epigenetics and transcriptomics features. For this purpose, we utilized a dataset where reduced representation bisulfite sequencing (RRBS) and RNA-seq measurements were measured at the same time for peripheral blood samples of 182 individuals. Then we trained machine learning models (ElasticNet) using the methylation and gene expression features at the same time. While the most accurate models tended to use exclusively methylation features, we were able to develop highly accurate multi-omics aging clocks too (called CpGenAge). Both the canonical and the non-canonical Nf-{kappa}B signaling pathways, with the genes EDA, EDA2R, EDARADD, and CD70, were overrepresented among the gene expression features of the multi-omics aging clocks. The EDARADD, which is a unique hallmark of aging, was represented among both the gene expression and methylation features. By developing single-omic clocks on the same multi-omics dataset, we found that epigenetic age acceleration and transcriptomics age acceleration do not correlate with each other, further supporting the benefits of our multi-omics approach. In summary, here, we demonstrate that multi-omics aging clocks are useful tools to investigate aging and biological age at the multi-omics level.

Lipids are a heterogenous class of molecules involved in signaling, cell structure and energy storage. Lipid metabolism is dysregulated in aging and aging-related diseases such as cancer, metabolic disorders, and neurodegeneration. In this study, we developed a biological age predictor - a Lipid Aging Clock - based on human serum lipidome data of pancreatic ductal adenocarcinoma (PDAC) patients, that has a Pearson correlation coefficient of 0.81 to chronological age with a median absolute error of 4.5 years. This shows that it is possible to build aging clocks measuring aging from pathological cohorts. We find that LipidAgeAcceleration is increased in both PDAC and pancreatitis, indicating that these pancreatic conditions accelerate aging or that individuals with age acceleration or more likely to acquire them (or both). Furthermore, the lipid age clock is predictive of PDAC survival, where positive accelerated Lipid Age is associated with an 86% higher mortality risk. Among the lipid species associated with LipidAgeAcceleration, Ceramides, Sphingomyelins and Glycerophosphocholines, have statistically significant hazard ratios, and directly impact increased mortality. Pathway analysis of lipid species selected by the lipid clock further identifies age-dependent dysregulation of specific lipid pathways, including Sphingolipid, Glycerolipid, Glycerophospholipid metabolism, and steroid biosynthesis. Sphingolipid metabolism is significantly dysregulated in both aging and PDAC, connecting aging dynamics and cancer mortality. Moreover, sphingolipids are involved in inflammatory processes, and therefore the lipid aging clock could be, at least in part, reflecting inflammaging and is likely influenced by age-related alterations to the immune system. In summary, our work shows that lipid alterations are a robust biological age predictor with utility in cancer and aging research, as well as in predicting disease-associated outcomes.

The death toll of the COVID-19 pandemic has been unprecedented, due to both the high number of SARS-CoV-2 infections and the seriousness of the disease resulting from these infections. Here, we present mortality rates and case fatality rates for COVID-19 over the past year compared with other historic leading causes of death in the United States. Among the risk categories considered, COVID-19 is the third leading cause of death for individuals 40 years old and over, with an overall annual mortality rate of 325 deaths per 100K individuals, behind only cancer (385 deaths per 100K individuals) and heart disease (412 deaths per 100K individuals). In addition, for individuals 40 years old and over, the case fatality rate for COVID-19 is greater than the case fatality rate for motor vehicle accidents. In particular, for the age group 40-49, the relative case fatality rate of COVID-19 is 1.5 fold (95% CI: [1.3, 1.7]) that of a motor vehicle accident, demonstrating that SARS-CoV-2 infection may be significantly more dangerous than a car crash for this age group. For older adults, COVID-19 is even more dangerous, and the relative case fatality rate of COVID-19 is 29.4 fold (95% CI: [23.2, 35.7]) that of a motor vehicle accident for individuals over 80 years old. On the other hand, motor vehicle accidents have a 4.5 fold (95% CI: [3.9, 5.1]) greater relative case fatality rate compared to COVID-19 for the age group of 20-29 years. These results highlight the severity of the COVID-19 pandemic especially for adults above 40 years of age and underscore the need for large-scale preventative measures to mitigate risks for these populations. Given that FDA-authorized COVID-19 vaccines have now been validated by multiple studies for their outstanding real-world effectiveness and safety, vaccination of all individuals who are over 40 years of age is one of the most pressing public health priorities of our time.

BackgroundEpigenetic clocks based on DNA methylation (DNAm) are widely used indicators of biological aging; however, most established models have been developed using EPIC arrays and non-Japanese populations. The Methylation Screening Array (MSA), a cost-efficient platform with reduced CpG content, has not been evaluated for its capacity to support biological age estimation and biomarker prediction in Japanese cohorts. MethodsDNAm profiles and clinical laboratory measurements were obtained from 166 Japanese participants for model development; an independent cohort of 48 individuals processed at a separate institute was used for validation. A linear regression model was trained using the Elastic Net method to predict phenotypic age from MSA-derived methylation data, and a two-stage modeling (residual learning) framework integrating EPIC-based clock predictions with MSA-specific residual predictions was evaluated. Additional models were constructed to examine the predictability of 59 clinical biomarkers and their log-transformed variants, including sex-stratified analyses. ResultsThe MSA-based model accurately predicted phenotypic age in the validation dataset; prediction performance improved when the EPIC-based estimates were incorporated through the residual learning framework. Several clinical biomarkers, particularly those related to leukocyte composition and sex hormone regulation, were also predicted from the MSA data, although some markers were strongly affected by sex. Some of the nine constituent phenotypic age biomarkers were not individually predicted. ConclusionsMSA methylation profiles contain sufficient biological information for reliable prediction of epigenetic aging markers in Japanese individuals. These findings demonstrate the feasibility of applying cost-efficient MSA-based DNAm profiling for biological age prediction and provide a methodological foundation for expanding epigenetic biomarker applications in Japan.

Methylation-based epigenetic clocks are among the most accurate tools for predicting chronological age. Although DNA methylation (DNAm) at genomic CpG sites is linked to various regulatory mechanisms, the biological interpretability of epigenetic clocks remains surprisingly limited. One primary mechanism by which DNAm is thought to influence gene regulation is by modulating transcription factor binding activity. In this study, we examine established epigenetic clocks to assess the regulatory potential of their predictive CpGs during the aging process. Our analysis reveals that generally most CpG sites used by epigenetic clocks do not overlap known transcription factor binding sites (TFBSs), indicating that changes in TFBS dynamics may not account for prediction accuracy of these models. On the other hand, by identifying age-associated CpGs that overlap TFBSs, we identified transcription factors that may be involved in the aging process. Specifically, the TFBSs of ZBED1, NFE2, CEBPB, FOXP1, EGR1, SP1, PAX5, and MAZ were particularly enriched for age-associated CpGs, while RBPJ, NFIC, RELA, IKZF1, STAT3, and USF2 were significantly protected against methylation changes. By focusing on TFBS-associated CpGs, combined with additional feature selection and engineering steps, we developed an alternative, TFMethyl Clock model, outperforming several existing approaches. Target genes of model-selected, age-predictive CpGs are enriched in the interleukin-1b production and long- chain fatty acid metabolism pathways. In contrast, these CpGs themselves are enriched mainly at binding sites of NR2C2 TF. Furthermore, approximately three-fourths of the target genes downstream of age- predictive CpGs exhibit significant age-related changes, suggesting that our approach captures deeper insights into possible methylation-driven biological aging processes. Our findings demonstrate that incorporating regulatory loci into the design of epigenetic predictors may provide mechanistic insights into the aging process while maintaining or even improving the predictive power.

BackgroundImmunosenescence is an age-associated decrease in function of immune cells precipitated by a variety of mechanisms and affecting nearly every immune cell subset. In myeloid cell subsets, aging reduces numbers of phagocytes and impairs their functional abilities, including antigen presentation, phagocytosis, and bacterial clearance. Recently, we have described an aging effect on several functions indicating immunosenescence in monocytes, including impaired mitochondrial function and reduced inflammatory cytokine gene expression during stimulation with lipopolysaccharide (LPS). We hypothesized that circulating factors altered by the aging process underly these changes. Growth/differentiation factor-15 (GDF-15) is a distant member of the transforming growth factor-beta superfamily that has known anti-inflammatory effects in macrophages and has recently been shown to be highly differentially expressed during aging. We used biobanked serum and plasma samples to assay circulating GDF-15 levels in subjects from our previous studies and examined correlations between GDF-15 levels and monocyte mitochondrial function and inflammatory responses. ResultsMonocyte interleukin-6 production due to lipopolysaccharide stimulation was negatively correlated to plasma GDF-15 levels. Additionally, serum GDF-15 was positively correlated to circulating CD16+ monocyte proportions and negatively correlated to monocyte mitochondrial respiratory capacity. ConclusionsThe results of these analyses suggest that GDF-15 is a potential circulating factor affecting a variety of monocyte functions and promoting monocyte immunosenescence, and thus may be an attractive candidate for therapeutic intervention to ameliorate this.

This study evaluated whether the lactic acid bacteria Lactococcus lactis subsp. cremoris strain FC (FC) could ameliorate host defenses and cognitive ability and extend the lifespan of Caenorhabditis elegans, a model of senescence. The lifespan and resistance to physical, chemical, and biological stressors were compared between C. elegans fed FC and those fed Escherichia coli OP50 (OP), an international standard food for C. elegans. Living FC successfully extended the health span, enhanced host defense, and ameliorated the cognitive ability of the nematodes; even the exopolysaccharides (EPSes) of FC could extend the lifespan of C. elegans. The chemotaxis index, which was used to evaluate the senescence of sensory neurons, tended to decrease with aging; however, it was more stable in worms fed FC and was significantly higher than that of the control worms at 7 days of age. The worms fed FC were tolerant to Salmonella enterica serovar Enteritidis or Staphylococcus aureus infection and had better survival than the control worms fed OP. FC showed beneficial effects in C. elegans daf-16 and pmk-1 mutants, but not in skn-1 mutants. Since SKN-1 is the C. elegans ortholog of Nrf2, we measured the transcription of heme oxygenase-1 (HO-1), which is regulated by Nrf2, in murine macrophages and found that HO-1 mRNA expression was increased >5 times by inoculation with either FC cells or heat-killed bacteria with EPSes. Thus, both FC and the EPSes can affect longevity via the SKN-1/Nrf2 pathway in both nematodes and mammalian cells. IMPORTANCEAgeing is one of our greatest challenges. The World Health Organization proposed the concept of "Active Ageing" might encourage people to continue to work according to their capacities and preferences as they grow old and would prevent or delay disabilities and chronic diseases that are costly to both individuals and the society, considering that disease prevention is more economical than treatment. Probiotic bacteria such as lactobacilli are living microorganisms that exert beneficial effects on human health when ingested in sufficient amounts and can promote longevity. The significance of this study is that it revealed the anti-senescence and various beneficial effects of the probiotic representative bacterium Lactococcus lactis subsp. cremoris strain FC and its exopolysaccharides in the nematode Caenorhabditis elegans.