Development of a serum profile for healthy aging

Impact of dietary walnuts, a nutraceutical option, on circulating markers of metabolic dysregulation in a rodent cachectic tumor model

BACKGROUND

Nutraceutical foods, like walnuts which are rich in immunonutrients, can have medicinal benefits. Dietary walnuts have been shown to slow or prevent tumor growth in mice genetically programmed to grow breast or prostate tumors. This study investigated whether walnuts could exert the same preventable effect in a transplantable carcinoma rat model.

METHODS

Eighteen rats were randomly fed a diet containing walnuts (10% of food by weight), and 36 were fed a diet without walnuts (control) for 21 days. On day 22, 18 control diet rats were switched to the walnut diet. All other animals remained on their same diet. Within each diet group, 6 rats were implanted with the Ward colon carcinoma (TB), and 12 were sham-operated. Five days later, 6 sham-operated animals were weight-matched to a TB and then pair-fed for the remainder of the study. The remaining 6 sham-operated, or non-tumor-bearing rats, were ad-lib fed.

RESULTS

The tissue of the walnut-eating rats showed higher omega-3 fatty acid (immunonutrient) content which did not slow or prevent tumor growth or the loss of lean and fat mass typical of this TB model. In addition, blood glucose, insulin, IGF-1, and adiponectin levels were significantly lower in the TB, demonstrating metabolic dysregulation. Again, these changes were unaltered by consuming walnuts. Plasma proteomics identified six proteins elevated in the TB, but none could be connected with the observed metabolic dysregulation.

CONCLUSION

Although walnuts' rich immunonutrient content prevented tumor growth in genetically programmed mice models, there was no effect in this model.

Relationship of Haptoglobin Phenotypes With Sarcopaenia in Patients With Congestive Heart Failure

BACKGROUND

Systemic inflammation in patients with chronic heart failure (CHF) contributes to age-related muscle loss or sarcopaenia. However, the relationship of plasma haptoglobin (Hp), an acute-phase reactant, with muscle and physical health in CHF is unknown.

METHODS

This study investigated the associations of plasma haptoglobin levels and phenotypes with handgrip strength (HGS), appendicular skeletal muscle index (ASMI) and physical capacity in healthy controls (n=67) and CHF patients (n=61) aged 55-73 years.

RESULTS

Patients with CHF had higher plasma Hp levels and higher proportions of Hp2-2 phenotype when compared with healthy controls. Plasma Hp2-1 and Hp2-2 levels were negatively associated with HGS and ASMI in healthy controls and CHF (both p<0.05). A negative association of plasma Hp2-2 with gait speed and plasma Hp2-1 with daily steps count was also found in CHF (p<0.05). Patients with Hp2 phenotype showed higher expressions of inflammation and oxidative stress markers, as well as low scores on quality of life parameters.

CONCLUSIONS

Circulating Hp may be a valuable biomarker for assessing muscle health and physical capacity in CHF.

Mitochondrial-derived peptides: New markers for cardiometabolic dysfunction

Great attention is being paid to the evaluation of new markers in blood circulation for the estimation of tissue metabolism disturbance. This endogenous disturbance may contribute to the onset and progression of cardiometabolic disease. In addition to their role in energy production and metabolism, mitochondria play a main function in cellular mechanisms, including apoptosis, oxidative stress and calcium homeostasis. Mitochondria produce mitochondrial-derived peptides that mediate the transcriptional stress response by translocating into the nucleus and interacting with deoxyribonucleic acid. This class of peptides includes humanin, mitochondrial open reading frame of the 12S ribosomal ribonucleic acid type c (MOTS-c) and small humanin-like peptides. Mitochondrial-derived peptides are regulators of metabolism, exerting cytoprotective effects through antioxidative stress, anti-inflammatory responses and antiapoptosis; they are emerging biomarkers reflecting mitochondrial function, and the circulating concentration of these proteins can be used to diagnose cardiometabolic dysfunction. The aims of this review are: (1) to describe the emerging role for mitochondrial-derived peptides as biomarkers; and (2) to discuss the therapeutic application of these peptides.

Can Serum Nitrosoproteome Predict Longevity of Aged Women?

Aging is characterized by increase in reactive oxygen (ROS) and nitrogen (RNS) species, key factors of cardiac failure and disuse-induced muscle atrophy. This study focused on serum nitroproteome as a trait of longevity by adopting two complementary gel-based techniques: two-dimensional differential in gel electrophoresis (2-D DIGE) and Nitro-DIGE coupled with mass spectrometry of albumin-depleted serum of aged (A, n = 15) and centenarian (C, n = 15) versus young females (Y, n = 15). Results indicate spots differently expressed in A and C compared to Y and spots changed in A vs. C. Nitro-DIGE revealed nitrosated protein spots in A and C compared to Y and spots changed in A vs. C only (p-value < 0.01). Nitro-proteoforms of alpha-1-antitripsin (SERPINA1), alpha-1-antichimotripsin (SERPINA3), ceruloplasmin (CP), 13 proteoforms of haptoglobin (HP), and inactive glycosyltransferase 25 family member 3 (CERCAM) increased in A vs. Y and C. Conversely, nitrosation levels decreased in C vs. Y and A, for immunoglobulin light chain 1 (IGLC1), serotransferrin (TF), transthyretin (TTR), and vitamin D-binding protein (VDBP). Immunoblottings of alcohol dehydrogenase 5/S-nitrosoglutathione reductase (ADH5/GSNOR) and thioredoxin reductase 1 (TRXR1) indicated lower levels of ADH5 in A vs. Y and C, whereas TRXR1 decreased in A and C in comparison to Y. In conclusion, the study identified putative markers in C of healthy aging and high levels of ADH5/GSNOR that can sustain the denitrosylase activity, promoting longevity.

Systematic review and analysis of human proteomics aging studies unveils a novel proteomic aging clock and identifies key processes that change with age

The development of clinical interventions that significantly improve human healthspan requires robust markers of biological age as well as thoughtful therapeutic targets. To promote these goals, we performed a systematic review and analysis of human aging and proteomics studies. The systematic review includes 36 different proteomics analyses, each of which identified proteins that significantly changed with age. We discovered 1,128 proteins that had been reported by at least two or more analyses and 32 proteins that had been reported by five or more analyses. Each of these 32 proteins has known connections relevant to aging and age-related disease. GDF15, for example, extends both lifespan and healthspan when overexpressed in mice and is additionally required for the anti-diabetic drug metformin to exert beneficial effects on body weight and energy balance. Bioinformatic enrichment analyses of our 1,128 commonly identified proteins heavily implicated processes relevant to inflammation, the extracellular matrix, and gene regulation. We additionally propose a novel proteomic aging clock comprised of proteins that were reported to change with age in plasma in three or more different studies. Using a large patient cohort comprised of 3,301 subjects (aged 18-76 years), we demonstrate that this clock is able to accurately predict human age.

A model for comprehensive oral biological age score with oral and systemic clinical parameters

BACKGROUND

Biological age reflects the functional status of an individual. The purpose of the study was to develop a model for estimating oral biological age with oral and systemic parameters.

METHODS

A total of 248 subjects who had a routine health check were assessed with oral and general clinical examination. Chi-square test was performed to screen oral clinical candidate indicators. General parameters were analyzed by Pearson correlation coefficient and principal component analysis to develop a general biological age score. A final comprehensive model of oral biological age score was established by combining oral and general biological age score.

RESULTS

A total of eight oral indicators (mucosal blood blister, mucosal dryness, impacted tooth, missing teeth, residual crowns, dental calculus, gingival hyperemia, and gingival recession) and 10 general clinical indicators (triglyceride, creatinine, blood urea nitrogen, glucose, total cholesterol, mean erythrocyte hemoglobin concentration, mean erythrocyte hemoglobin, uric acid, body weight, and systolic blood pressure) were selected for oral and general biological age score, respectively (r > 0.25, P < 0.05). A model of comprehensive oral biological age score was then formed by principal component analysis: 0.046 triglyceride + 0.010 creatinine + 0.141 blood urea nitrogen + 0.048 glucose + 0.068 total cholesterol + 0.014 mean erythrocyte hemoglobin concentration + 0.082 mean erythrocyte hemoglobin + 0.001 uric acid + 0.020 body weight + 0.005 systolic blood pressure + 0.037 oral biological age score -10.908. The score was increased accordingly with CA.

CONCLUSION

Oral biological age can be easily estimated clinically by the model of comprehensive oral biological age score using oral and systemic clinical parameters by general practitioners.

Age-Associated Changes in the Immune System and Blood⁻Brain Barrier Functions

Age is associated with altered immune functions that may affect the brain. Brain barriers, including the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB), are important interfaces for neuroimmune communication, and are affected by aging. In this review, we explore novel mechanisms by which the aging immune system alters central nervous system functions and neuroimmune responses, with a focus on brain barriers. Specific emphasis will be on recent works that have identified novel mechanisms by which BBB/BCSFB functions change with age, interactions of the BBB with age-associated immune factors, and contributions of the BBB to age-associated neurological disorders. Understanding how age alters BBB functions and responses to pathological insults could provide important insight on the role of the BBB in the progression of cognitive decline and neurodegenerative disease.

Age and Periodontal Health - Immunological View

PURPOSE OF THE REVIEW

Aging clearly impacts a wide array of systems, in particular the breadth of the immune system leading to immunosenescence, altered immunoactivation, and coincident inflammaging processes. The net result of these changes leads to increased susceptibility to infections, increased neoplastic occurrences, and elevated frequency of autoimmune diseases with aging. However, as the bacteria in the oral microbiome that contribute to the chronic infection of periodontitis is acquired earlier in life, the characteristics of the innate and adaptive immune systems to regulate these members of the autochthonous microbiota across the lifespan remains ill defined.

RECENT FINDINGS

Clear data demonstrate that both cells and molecules of the innate and adaptive immune response are adversely impacted by aging, including in the oral cavity, yielding a reasonable tenet that the increased periodontitis noted in aging populations is reflective of the age-associated immune dysregulation. Additionally, this facet of host-microbe interactions and disease needs to accommodate the population variation in disease onset and progression, which may also reflect an accumulation of environmental stressors and/or decreased protective nutrients that could function at the gene level (ie. epigenetic) or translational level for production and secretion of immune system molecules.

SUMMARY

Finally, the majority of studies of aging and periodontitis have emphasized the increased prevalence/severity of disease with aging, all based upon chronological age. However, evolving areas of study focusing on "biological aging" to help account for population variation in disease expression, may suggest that chronic periodontitis represents a co-morbidity that contributes to "gerovulnerability" within the population.

Plasma proteomic signature of age in healthy humans

To characterize the proteomic signature of chronological age, 1,301 proteins were measured in plasma using the SOMAscan assay (SomaLogic, Boulder, CO, USA) in a population of 240 healthy men and women, 22-93 years old, who were disease- and treatment-free and had no physical and cognitive impairment. Using a p ≤ 3.83 × 10-5 significance threshold, 197 proteins were positively associated, and 20 proteins were negatively associated with age. Growth differentiation factor 15 (GDF15) had the strongest, positive association with age (GDF15; 0.018 ± 0.001, p = 7.49 × 10-56 ). In our sample, GDF15 was not associated with other cardiovascular risk factors such as cholesterol or inflammatory markers. The functional pathways enriched in the 217 age-associated proteins included blood coagulation, chemokine and inflammatory pathways, axon guidance, peptidase activity, and apoptosis. Using elastic net regression models, we created a proteomic signature of age based on relative concentrations of 76 proteins that highly correlated with chronological age (r = 0.94). The generalizability of our findings needs replication in an independent cohort.

Proteomics and metabolomics in ageing research: from biomarkers to systems biology

Age is the single greatest risk factor for a wide range of diseases, and as the mean age of human populations grows steadily older, the impact of this risk factor grows as well. Laboratory studies on the basic biology of ageing have shed light on numerous genetic pathways that have strong effects on lifespan. However, we still do not know the degree to which the pathways that affect ageing in the lab also influence variation in rates of ageing and age-related disease in human populations. Similarly, despite considerable effort, we have yet to identify reliable and reproducible 'biomarkers', which are predictors of one's biological as opposed to chronological age. One challenge lies in the enormous mechanistic distance between genotype and downstream ageing phenotypes. Here, we consider the power of studying 'endophenotypes' in the context of ageing. Endophenotypes are the various molecular domains that exist at intermediate levels of organization between the genotype and phenotype. We focus our attention specifically on proteins and metabolites. Proteomic and metabolomic profiling has the potential to help identify the underlying causal mechanisms that link genotype to phenotype. We present a brief review of proteomics and metabolomics in ageing research with a focus on the potential of a systems biology and network-centric perspective in geroscience. While network analyses to study ageing utilizing proteomics and metabolomics are in their infancy, they may be the powerful model needed to discover underlying biological processes that influence natural variation in ageing, age-related disease, and longevity.

Increased levels of hyper-stable protein aggregates in plasma of older adults

Proteins that misfold into hyper-stable/degradation-resistant species during aging may accumulate and disrupt protein homeostasis (i.e., proteostasis), thereby posing a survival risk to any organism. Using the method diagonal two-dimensional (D2D) SDS-PAGE, which separates hyper-stable SDS-resistant proteins at a proteomics level, we analyzed the plasma of healthy young (<30 years) and older (60-80 years) adults. We discovered the presence of soluble SDS-resistant protein aggregates in the plasma of older adults, but found significantly lower levels in the plasma of young adults. We identified the inflammation-related chaperone protein haptoglobin as the main component of the hyper-stable aggregates. This observation is consistent with the growing link between accumulations of protein aggregates and aging across many organisms. It is plausible higher amounts of SDS-resistant protein aggregates in the plasma of older adults may reflect a compromise in proteostasis that may potentially indicate cellular aging and/or disease risk. The results of this study have implications for further understanding the link between aging and the accumulation of protein aggregates, as well as potential for the development of aging-related biomarkers. More broadly, this novel application of D2D SDS-PAGE may be used to identify, quantify, and characterize the degradation-resistant protein aggregates in human plasma or any biological system.

Proteome analysis in the assessment of ageing

Based on demographic trends, the societies in many developed countries are facing an increasing number and proportion of people over the age of 65. The raise in elderly populations along with improved health-care will be concomitant with an increased prevalence of ageing-associated chronic conditions like cardiovascular, renal, and respiratory diseases, arthritis, dementia, and diabetes mellitus. This is expected to pose unprecedented challenges both for individuals and societies and their health care systems. An ultimate goal of ageing research is therefore the understanding of physiological ageing and the achievement of 'healthy' ageing by decreasing age-related pathologies. However, on a molecular level, ageing is a complex multi-mechanistic process whose contributing factors may vary individually, partly overlap with pathological alterations, and are often poorly understood. Proteome analysis potentially allows modelling of these multifactorial processes. This review summarises recent proteomic research on age-related changes identified in animal models and human studies. We combined this information with pathway analysis to identify molecular mechanisms associated with ageing. We identified some molecular pathways that are affected in most or even all organs and others that are organ-specific. However, appropriately powered studies are needed to confirm these findings based in in silico evaluation.

Aging is not a disease: implications for intervention

Aging of biological systems occurs in spite of numerous complex pathways of maintenance, repair and defense. There are no gerontogenes which have the specific evolutionary function to cause aging. Although aging is the common cause of all age-related diseases, aging in itself cannot be considered a disease. This understanding of aging as a process should transform our approach towards interventions from developing illusory anti-aging treatments to developing realistic and practical methods for maintaining health throughout the lifespan. The concept of homeodynamic space can be a useful one in order to identify a set of measurable, evidence-based and demonstratable parameters of health, robustness and resilience. Age-induced health problems, for which there are no other clear-cut causative agents, may be better tackled by focusing on health mechanisms and their maintenance, rather than only disease management and treatment. Continuing the disease-oriented research and treatment approaches, as opposed to health-oriented and preventive strategies, are economically, socially and psychologically unsustainable.

Secretory defect and cytotoxicity: the potential disease mechanisms for the retinitis pigmentosa (RP)-associated interphotoreceptor retinoid-binding protein (IRBP)

Interphotoreceptor retinoid-binding protein (IRBP) secreted by photoreceptors plays a pivotal role in photoreceptor survival and function. Recently, a D1080N mutation in IRBP was found in patients with retinitis pigmentosa, a frequent cause of retinal degeneration. The molecular and cellular bases for pathogenicity of the mutation are unknown. Here, we show that the mutation abolishes secretion of IRBP and results in formation of insoluble high molecular weight complexes via disulfide bonds. Co-expression of protein disulfide isomerase A2 that regulates disulfide bond formation or introduction of double Cys-to-Ala substitutions at positions 304 and 1175 in D1080N IRBP promoted secretion of the mutated IRBP. D1080N IRBP was not transported to the Golgi apparatus, but accumulated in the endoplasmic reticulum (ER), bound with the ER-resident chaperone proteins such as BiP, protein disulfide isomerase, and heat shock proteins. Splicing of X-box-binding protein-1 mRNA, expression of activating transcription factor 4 (ATF4), and cleavage of ATF6 were significantly increased in cells expressing D1080N IRBP. Moreover, D1080N IRBP induced up-regulation and nuclear translocation of the C/EBP homologous protein, a proapoptotic transcription factor associated with the unfolded protein response. These results indicate that loss of normal function (nonsecretion) and gain of cytotoxic function (ER stress) are involved in the disease mechanisms of D1080N IRBP. Chemical chaperones and low temperature, which help proper folding of many mutated proteins, significantly rescued secretion of D1080N IRBP, suggesting that misfolding is the molecular basis for pathogenicity of D1080N substitution and that chemical chaperones are therapeutic candidates for the mutation-caused blinding disease.

Proteomic profiles reveal age-related changes in coelomic fluid of sea urchin species with different life spans

Sea urchins have a different life history from humans and traditional model organisms used to study the process of aging. Sea urchins grow indeterminately, reproduce throughout their life span and some species have been shown to exhibit negligible senescence with no increase in mortality rate at advanced ages. Despite these properties, different species of sea urchins are reported to have very different natural life spans providing a unique model to investigate cellular mechanisms underlying life span determination and negligible senescence. To gain insight into the biological changes that accompany aging in these animals, proteomic profiles were examined in coelomic fluid from young and old sea urchins of three species with different life spans: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate life span. The proteomic profiles of cell-free coelomic fluid were complex with many proteins exhibiting different forms and extensive post-translational modifications. Approximately 20% of the protein spots on 2-D gels showed more than two-fold change with age in each of the species. Changes that are consistent with age in all three species may prove to be useful biomarkers for age-determination for these commercially fished marine invertebrates and also may provide clues to mechanisms of negligible senescence. Among the proteins that change with age, the ectodomain of low-density lipoprotein receptor-related protein 4 (LRP4) was significantly increased in the coelomic fluid of all three sea urchin species suggesting that the Wnt signaling pathway should be further investigated for its role in negligible senescence.

Profiling plasma peptides for the identification of potential ageing biomarkers in Chinese Han adults

Advancing age is associated with cardiovascular disease, diabetes mellitus and cancer, and shows significant inter-individual variability. To identify ageing-related biomarkers we performed a proteomic analysis on 1890 Chinese Han individuals, 1136 males and 754 females, aged 18 to 82 years, using weak cation exchange magnetic bead based MALDI-TOF-MS analysis. The study identified 44 peptides which varied in concentration in different age groups. In particular, apolipoprotein A-I (ApoA1) concentration gradually increased between 18 to 50 years of age, the levels of fibrinogen alpha (FGA) decreased over the same age span, while albumin (ALB) was significantly degraded in middle-aged individuals. In addition, the plasma peptide profiles of FGA and four other unidentified proteins were found to be gender-dependent. Plasma proteins such as FGA, ALB and ApoA1 are significantly correlated with age in the Chinese Han population and could be employed as indicative ageing-related biomarkers.

DEFOG: discrete enrichment of functionally organized genes

High-throughput biological experiments commonly result in a list of genes or proteins of interest. In order to understand the observed changes of the genes and to generate new hypotheses, one needs to understand the functions and roles of the genes and how those functions relate to the experimental conditions. Typically, statistical tests are performed in order to detect enriched Gene Ontology categories or pathways, i.e. the categories are observed in the genes of interest more often than is expected by chance. Depending on the number of genes and the complexity and quantity of functions in which they are involved, such an analysis can easily result in hundreds of enriched terms. To this end we developed DEFOG, a web-based application that facilitates the functional analysis of gene sets by hierarchically organizing the genes into functionally related modules. Our computational pipeline utilizes three powerful tools to achieve this goal: (1) GeneMANIA creates a functional consensus network of the genes of interest based on gene-list-specific data fusion of hundreds of genomic networks from publicly available sources; (2) Transitivity Clustering organizes those genes into a clear hierarchy of functionally related groups, and (3) Ontologizer performs a Gene Ontology enrichment analysis on the resulting gene clusters. DEFOG integrates this computational pipeline within an easy-to-use web interface, thus allowing for a novel visual analysis of gene sets that aids in the discovery of potentially important biological mechanisms and facilitates the creation of new hypotheses. DEFOG is available at http://www.mooneygroup.org/defog.

Proteomic screening of glycoproteins in human plasma for frailty biomarkers

The application of proteomics methodology for analyzing human blood samples is of increasing importance as a noninvasive method for understanding, detecting, and monitoring disease. In particular, glycoproteomic analysis may be useful in the study of age-related diseases and syndromes, such as frailty. This study demonstrates the use of methodology for isolating plasma glycoproteins using lectins, comparing the glycoproteome by frailty status using two-dimensional polyacrylamide gel electrophoresis and identifying glycoproteins using mass spectrometry. In a pilot study, we found seven glycoproteins to differ by at least twofold in prefrail compared with nonfrail older adults, including haptoglobin, transferrin, and fibrinogen, consistent with known inflammatory and hematologic changes associated with frailty. Enzyme-linked immunosorbent assay analysis found that plasma transferrin concentration was increased in frail and prefrail older adults compared with nonfrail, confirming our proteomic findings. This work provides evidence for using a reproducible methodology for conducting clinical proteomic comparative studies of age-related diseases.

Human serum N-glycan profiles are age and sex dependent

BACKGROUND

protein glycosylation varies with the physiological and pathological status of the cell. Consequently, analysis of protein-linked glycans has growing importance both in basic glycobiological research and as a potential tool for monitoring the physiological state in humans.

DESIGN, SETTING AND PARTICIPANTS

a total of 265 healthy northern Chinese men and women were grouped by age and gender. The mean age in males and females was similar.

OBJECTIVE

the study is aimed to evaluate the effects of the age and gender on the human serum N-glycans profiles in the clinical diagnose of ageing and disease.

METHODS

the 265 human serum N-glycan profiles were obtained by DNA sequencer-assisted fluorophore-assisted carbohydrate electrophoresis. Comparison of N-glycan profiles was carried out among the different genders and age groups and the data were analysed with the GeneMapper software.

RESULTS

age-related changes in the three N-glycan structures (NGA2F, NGA2FB and NA2F) were observed. Interestingly, fucosylation of N-glycans was significantly different (P < 0.0001) between men and women: more core-α-1,6-fucosylated glycans were detected in women, whereas more branching-α-1,3-fucosylated N-glycans were seen in men.

CONCLUSIONS

the N-glycome profile in serum is gender and age dependent. This should be taken into consideration in the development of serum glycome markers.