Age‐associated adipose tissue inflammation promotes monocyte chemotaxis and enhances atherosclerosis

Although aging enhances atherosclerosis, we do not know if this occurs via alterations in circulating immune cells, lipid metabolism, vasculature, or adipose tissue. Here, we examined whether aging exerts a direct pro‐atherogenic effect on adipose tissue in mice. After demonstrating that aging augmented the inflammatory profile of visceral but not subcutaneous adipose tissue, we transplanted visceral fat from young or aged mice onto the right carotid artery of Ldlr ^−/− recipients. Aged fat transplants not only increased atherosclerotic plaque size with increased macrophage numbers in the adjacent carotid artery, but also in distal vascular territories, indicating that aging of the adipose tissue enhances atherosclerosis via secreted factors. By depleting macrophages from the visceral fat, we identified that adipose tissue macrophages are major contributors of the secreted factors. To identify these inflammatory factors, we found that aged fat transplants secreted increased levels of the inflammatory mediators TNFα, CXCL2, and CCL2, which synergized to promote monocyte chemotaxis. Importantly, the combined blockade of these inflammatory mediators impeded the ability of aged fat transplants to enhance atherosclerosis. In conclusion, our study reveals that aging enhances atherosclerosis via increased inflammation of visceral fat. Our study suggests that future therapies targeting the visceral fat may reduce atherosclerosis disease burden in the expanding older population.     

Aortic VCAM‐1: an early marker of vascular inflammation in collagen‐induced arthritis

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in rheumatoid arthritis (RA). There are limited experimental data on vascular involvement in arthritis models. To study the link between CVD and inflammation in RA, we developed a model of vascular dysfunction and articular inflammation by collagen‐induced arthritis (CIA) in C57Bl/6 (B6) mice. We studied the expression of vascular inflammatory markers in CIA with and without concomitant hyperlipidic diet (HD). Collagen‐induced arthritis was induced with intradermal injection of chicken type‐II collagen followed by a boost 21 days later. Mice with and without CIA were fed a standard diet or an HD for 12 weeks starting from the day of the boost. Arthritis severity was evaluated with a validated clinical score. Aortic mRNA levels of vascular cell adhesion molecule‐1 (VCAM‐1), inducible nitric oxide synthase (iNOS) and interleukin‐17 were analysed by quantitative RT‐PCR. Vascular cell adhesion molecule‐1 localization in the aortic sinus was determined by immunohistochemistry. Atherosclerotic plaque presence was assessed in aortas. Collagen‐induced arthritis was associated with increased expression of VCAM‐1, independent of diet. VCAM‐1 overexpression was detectable as early as 4 weeks after collagen immunization and persisted after 15 weeks. The HD induced atheroma plaque formation and aortic iNOS expression regardless of CIA. Concomitant CIA and HD had no additive effect on atheroma or VCAM‐1 or iNOS expression. CIA and an HD diet induced a distinct and independent expression of large‐vessel inflammation markers in B6 mice. This model may be relevant for the study of CVD in RA.     

Age-associated adipose tissue inflammation promotes monocyte chemotaxis and enhances atherosclerosis

Although aging enhances atherosclerosis, we do not know if this occurs via alterations in circulating immune cells, lipid metabolism, vasculature, or adipose tissue. Here, we examined whether aging exerts a direct pro-atherogenic effect on adipose tissue in mice. After demonstrating that aging augmented the inflammatory profile of visceral but not subcutaneous adipose tissue, we transplanted visceral fat from young or aged mice onto the right carotid artery of Ldlr^−/− recipients. Aged fat transplants not only increased atherosclerotic plaque size with increased macrophage numbers in the adjacent carotid artery, but also in distal vascular territories, indicating that aging of the adipose tissue enhances atherosclerosis via secreted factors. By depleting macrophages from the visceral fat, we identified that adipose tissue macrophages are major contributors of the secreted factors. To identify these inflammatory factors, we found that aged fat transplants secreted increased levels of the inflammatory mediators TNFα, CXCL2, and CCL2, which synergized to promote monocyte chemotaxis. Importantly, the combined blockade of these inflammatory mediators impeded the ability of aged fat transplants to enhance atherosclerosis. In conclusion, our study reveals that aging enhances atherosclerosis via increased inflammation of visceral fat. Our study suggests that future therapies targeting the visceral fat may reduce atherosclerosis disease burden in the expanding older population.     

The role of monocytosis and neutrophilia in atherosclerosis

Monocytosis and neutrophilia are frequent events in atherosclerosis. These phenomena arise from the increased proliferation of hematopoietic stem and multipotential progenitor cells (HSPCs) and HSPC mobilization from the bone marrow to other immune organs and circulation. High cholesterol and inflammatory signals promote HSPC proliferation and preferential differentiation to the myeloid precursors (i.e., myelopoiesis) that than give rise to pro‐inflammatory immune cells. These cells accumulate in the plaques thereby enhancing vascular inflammation and contributing to further lesion progression. Studies in animal models of atherosclerosis showed that manipulation with HSPC proliferation and differentiation through the activation of LXR‐dependent mechanisms and restoration of cholesterol efflux may have a significant therapeutic potential.     

Age‐associated downregulation of vasohibin‐1 in vascular endothelial cells

Vasohibin‐1 (VASH1) is an angiogenesis‐inhibiting factor synthesized by endothelial cells (ECs) and it also functions to increase stress tolerance of ECs, which function is critical for the maintenance of vascular integrity. Here, we examined whether the expression of VASH1 would be affected by aging. We passaged human umbilical vein endothelial cells (HUVECs) and observed that VASH1 was downregulated in old HUVECs. This decrease in VASH1 expression with aging was confirmed in mice. To explore the mechanism of this downregulation, we compared the expression of microRNAs between old and young HUVECs by performing microarray analysis. Among the top 20 microRNAs that were expressed at a higher level in old HUVECs, the third highest microRNA, namely miR‐22‐3p, had its binding site on the 3′ UTR of VASH1 mRNA. Experiments with microRNA mimic and anti‐miR revealed that miR‐22‐3p was involved at least in part in the downregulation of VASH1 in ECs during replicative senescence. We then clarified the significance of this defective expression of VASH1 in the vasculature. When a cuff was placed around the femoral arteries of wild‐type mice and VASH1‐null mice, neointimal formation was augmented in the VASH1‐null mice accompanied by an increase in adventitial angiogenesis, macrophage accumulation in the adventitia, and medial/neointimal proliferating cells. These results indicate that in replicative senescence, the downregulation of VASH1 expression in ECs was caused, at least in part, by the alteration of microRNA expression. Such downregulation of VASH1 might be involved in the acceleration of age‐associated vascular diseases.     

Aging‐related carcinoembryonic antigen‐related cell adhesion molecule 1 signaling promotes vascular dysfunction

Aging is an independent risk factor for cardiovascular diseases and therefore of particular interest for the prevention of cardiovascular events. However, the mechanisms underlying vascular aging are not well understood. Since carcinoembryonic antigen‐related cell adhesion molecule 1 (CEACAM1) is crucially involved in vascular homeostasis, we sought to identify the role of CEACAM1 in vascular aging. Using human internal thoracic artery and murine aorta, we show that CEACAM1 is upregulated in the course of vascular aging. Further analyses demonstrated that TNF‐α is CEACAM1‐dependently upregulated in the aging vasculature. Vice versa, TNF‐α induces CEACAM1 expression. This results in a feed‐forward loop in the aging vasculature that maintains a chronic pro‐inflammatory milieu. Furthermore, we demonstrate that age‐associated vascular alterations, that is, increased oxidative stress and vascular fibrosis, due to increased medial collagen deposition crucially depend on the presence of CEACAM1. Additionally, age‐dependent upregulation of vascular CEACAM1 expression contributes to endothelial barrier impairment, putatively via increased VEGF/VEGFR‐2 signaling. Consequently, aging‐related upregulation of vascular CEACAM1 expression results in endothelial dysfunction that may promote atherosclerotic plaque formation in the presence of additional risk factors. Our data suggest that CEACAM1 might represent an attractive target in order to delay physiological aging and therefore the transition to vascular disorders such as atherosclerosis.     

The dynamics of gut‐associated microbial communities during inflammation

Our intestine is host to a large microbial community (microbiota) that educates the immune system and confers niche protection. Profiling of the gut‐associated microbial community reveals a dominance of obligate anaerobic bacteria in healthy individuals. However, intestinal inflammation is associated with a disturbance of the microbiota—known as dysbiosis—that often includes an increased prevalence of facultative anaerobic bacteria. This group contains potentially harmful bacterial species, the bloom of which can further exacerbate inflammation. Here, we review the mechanisms that generate changes in the microbial community structure during inflammation. One emerging concept is that electron acceptors generated as by‐products of the host inflammatory response feed facultative anaerobic bacteria selectively, thereby increasing their prevalence within the community. This new paradigm has broad implications for understanding dysbiosis during gut inflammation and identifies potential targets for intervention strategies.     

Age‐associated synapse elimination in mouse parasympathetic ganglia

Little is known about the effects of aging on synapses in the mammalian nervous system. We examined the innervation of individual mouse submandibular ganglion (SMG) neurons for evidence of age‐related changes in synapse efficacy and number. For approximately 85% of adult life expectancy (30 months) the efficacy of synaptic transmission, as determined by excitatory postsynaptic potential (EPSP) amplitudes, remains constant. Similarly, the number of synapses contacting individual SMG neurons is also unchanged. After 30 months of age, however, some neurons (23%) dramatically lose synaptic input exhibiting both smaller EPSP amplitude and fewer synaptic boutons. Attenuation of both the amplitude and frequency of miniature EPSPs was also observed in neurons from aged animals. Electron micrographs revealed that, although there were many vesicle‐laden preganglionic axonal processes in the vicinity of the postsynaptic membrane, the number of synaptic contacts was significantly lower in old animals. These results demonstrate primary, age‐associated synapse elimination with functional consequences that cannot be explained by pre‐ or postsynaptic cell death. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 214–226, 2004     

Aging influences the cardiac macrophage phenotype and function during steady state and during inflammation

Aging‐mediated immune dysregulation affects the normal cardiac immune cell phenotypes and functions, resulting in cardiac distress. During cardiac inflammation, immune activation is critical for mounting the regenerative responses to maintain normal heart function. We investigated the impact of aging on myeloid cell phenotype and function during cardiac inflammation induced by a sub‐lethal dose of LPS. Our data show that hearts of old mice contain more myeloid cells than the hearts of young mice. However, while the number of monocytic‐derived suppressor cells did not differ between young and old mice, monocytic‐derived suppressor cells from old mice were less able to suppress T‐cell proliferation. Since cardiac resident macrophages (CRMs) are important for immune surveillance, clearance of dead cells, and tissue repair, we focused our studies on CRMs phenotype and function during steady state and LPS treatment. In the steady state, we observed significantly more MHC‐II^low and MHC‐II^high CRMs in the hearts of old mice; however, these populations were decreased in both young and aged mice upon LPS treatment and the decrease in CRM populations correlated with defects in cardiac electrical activity. Notably, mice treated with a liver X receptor (LXR) agonist showed an increase in MerTK expression in CRMs of both young and old mice, which resulted in the reversal of cardiac electrical dysfunction caused by lipopolysaccharide (LPS). We conclude that aging alters the phenotype of CRMs, which contributes to the dysregulation of cardiac electrical dysfunction during infection in aged mice.     

Age‐related sensitivity to endotoxin‐induced liver inflammation: Implication of inflammasome/IL‐1β for steatohepatitis

Aging is associated with increased vulnerability to inflammatory challenge. However, the effects of altered inflammatory response on the metabolic status of tissues or organs are not well documented. In this study, we present evidence demonstrating that lipopolysaccharide (LPS)-induced upregulation of the inflammasome/IL-1β pathway is accompanied with an increased inflammatory response and abnormal lipid accumulation in livers of aged rats. To monitor the effects of aging on LPS-induced inflammation, we administered LPS (2 mg kg⁻¹) to young (6-month old) and aged (24-month old) rats and found abnormal lipid metabolism in only aged rats with increased lipid accumulation in the liver. This lipid accumulation in the liver was due to the dysregulation of PPARα and SREBP1c. We also observed severe liver inflammation in aged rats as indicated by increased ALT levels in serum and increased Kupffer cells in the liver. Importantly, among many inflammation-associated factors, the aged rat liver showed chronically increased IL-1β production. Increased levels of IL-1β were caused by the upregulation of caspase-1 activity and inflammasome activation. In vitro studies with HepG2 cells demonstrated that treatment with IL-1β significantly induced lipid accumulation in hepatocytes through the regulation of PPARα and SREBP1c. In summary, we demonstrated that LPS-induced liver inflammation and lipid accumulation were associated with a chronically overactive inflammasome/IL-1β pathway in aged rat livers. Based on the present findings, we propose a mechanism of aging-associated progression of steatohepatitis induced by endotoxin, delineating a pathogenic role of the inflammasome/IL-1β pathway involved in lipid accumulation in the liver.     

Contribution of vascular cell-derived cytokines to innate and inflammatory pathways in atherogenesis

Inflammation is a central element of atherogenesis. Innate pathways contribute to vascular inflammation. However, the initial molecular process(es) starting atherogenesis remain elusive. The various risk factors, represented by particular compounds (activators), may cause altered cellular functions in the endothelium (e.g. vascular endothelial cell activation or -dysfunction), in invading cells (e.g. inflammatory mediator production) or in local vessel wall cells (e.g. inflammatory mediators, migration), thereby triggering the innate inflammatory process. The cellular components of innate immunology include granulocytes, natural killer cells and monocytes. Among the molecular innate constituents are innate molecules, such as the toll-like receptors or innate cytokines. Interleukin-1 (IL-1) and IL-6 are among the innate cytokines. Cytokines are potent activators of a great number of cellular functions relevant to maintain or commove homeostasis of the vessel wall. Within the vessel wall, vascular smooth muscle cells (SMCs) can significantly contribute to the cytokine-dependent inflammatory network by: (i) production of cytokines, (ii) response to cytokines and (iii) cytokine-mediated interaction with invading leucocytes. The cytokines IL-1 and IL-6 are involved in SMC-leucocyte interaction. The IL-6 effects are proposed to be mediated by trans-signalling. Dysregulated cellular functions resulting from dysregulated cytokine production may be the cause of cell accumulation, subsequent low-density lipoprotein accumulation and deposition of extracellular matrix (ECM). The deposition of ECM, increased accumulation of leucocytes and altered levels of inflammatory mediators may constitute an 'innate-immunovascular-memory' resulting in an ever-growing response to anew invasion. Thus, SMC-fostered inflammation, promoted by invading innate cells, may be a potent component for development and acceleration of atherosclerosis.     

Positive crosstalk between arginase‐II and S6K1 in vascular endothelial inflammation and aging

Augmented activities of both arginase and S6K1 are involved in endothelial dysfunction in aging. This study was to investigate whether or not there is a crosstalk between arginase and S6K1 in endothelial inflammation and aging in senescent human umbilical vein endothelial cells and in aging mouse models. We show increased arginase‐II (Arg‐II) expression/activity in senescent endothelial cells. Silencing Arg‐II in senescent cells suppresses eNOS‐uncoupling, several senescence markers such as senescence‐associated‐β‐galactosidase activity, p53‐S15, p21, and expression of vascular adhesion molecule‐1 (VCAM1) and intercellular adhesion molecule‐1 (ICAM1). Conversely, overexpressing Arg‐II in nonsenescent cells promotes eNOS‐uncoupling, endothelial senescence, and enhances VCAM1/ICAM1 levels and monocyte adhesion, which are inhibited by co‐expressing superoxide dismutase‐1. Moreover, overexpressing S6K1 in nonsenescent cells increases, whereas silencing S6K1 in senescent cells decreases Arg‐II gene expression/activity through regulation of Arg‐II mRNA stability. Furthermore, S6K1 overexpression exerts the same effects as Arg‐II on endothelial senescence and inflammation responses, which are prevented by silencing Arg‐II, demonstrating a role of Arg‐II as the mediator of S6K1‐induced endothelial aging. Interestingly, mice that are deficient in Arg‐II gene (Arg‐II^?/?) are not only protected from age‐associated increase in Arg‐II, VCAM1/ICAM1, aging markers, and eNOS‐uncoupling in the aortas but also reveal a decrease in S6K1 activity. Similarly, silencing Arg‐II in senescent cells decreases S6K1 activity, demonstrating that Arg‐II also stimulates S6K1 in aging. Our study reveals a novel mechanism of mutual positive regulation between S6K1 and Arg‐II in endothelial inflammation and aging. Targeting S6K1 and/or Arg‐II may decelerate vascular aging and age‐associated cardiovascular disease development.     

Age‐associated cholesterol reduction triggers brain insulin resistance by facilitating ligand‐independent receptor activation and pathway desensitization

In the brain, insulin plays an important role in cognitive processes. During aging, these faculties decline, as does insulin signaling. The mechanism behind this last phenomenon is unclear. In recent studies, we reported that the mild and gradual loss of cholesterol in the synaptic fraction of hippocampal neurons during aging leads to a decrease in synaptic plasticity evoked by glutamate receptor activation and also by receptor tyrosine kinase (RTK) signaling. As insulin and insulin growth factor activity are dependent on tyrosine kinase receptors, we investigated whether the constitutive loss of brain cholesterol is also involved in the decay of insulin function with age. Using long‐term depression (LTD) induced by application of insulin to hippocampal slices as a read‐out, we found that the decline in insulin function during aging could be monitored as a progressive impairment of insulin‐LTD. The application of a cholesterol inclusion complex, which donates cholesterol to the membrane and increases membrane cholesterol levels, rescued the insulin signaling deficit and insulin‐LTD. In contrast, extraction of cholesterol from hippocampal neurons of adult mice produced the opposite effect. Furthermore, in vivo inhibition of Cyp46A1, an enzyme involved in brain cholesterol loss with age, improved insulin signaling. Fluorescence resonance energy transfer (FRET) experiments pointed to a change in receptor conformation by reduced membrane cholesterol, favoring ligand‐independent autophosphorylation. Together, these results indicate that changes in membrane fluidity of brain cells during aging play a key role in the decay of synaptic plasticity and cognition that occurs at this late stage of life.     

Age‐related degeneration of the egg‐laying system promotes matricidal hatching in Caenorhabditis elegans

The identification and characterization of age‐related degenerative changes is a critical goal because it can elucidate mechanisms of aging biology and contribute to understanding interventions that promote longevity. Here, we document a novel, age‐related degenerative change in C. elegans hermaphrodites, an important model system for the genetic analysis of longevity. Matricidal hatching—intra‐uterine hatching of progeny that causes maternal death—displayed an age‐related increase in frequency and affected ~70% of mated, wild‐type hermaphrodites. The timing and incidence of matricidal hatching were largely independent of the levels of early and total progeny production and the duration of male exposure. Thus, matricidal hatching appears to reflect intrinsic age‐related degeneration of the egg‐laying system rather than use‐dependent damage accumulation. Consistent with this model, mutations that extend longevity by causing dietary restriction significantly delayed matricidal hatching, indicating age‐related degeneration of the egg‐laying system is controlled by nutrient availability. To identify the underlying tissue defect, we analyzed serotonin signaling that triggers vulval muscle contractions. Mated hermaphrodites displayed an age‐related decline in the ability to lay eggs in response to exogenous serotonin, indicating that vulval muscles and/or a further downstream function that is necessary for egg laying degenerate in an age‐related manner. By characterizing a new, age‐related degenerative event displayed by C. elegans hermaphrodites, these studies contribute to understanding a frequent cause of death in mated hermaphrodites and establish a model of age‐related reproductive complications that may be relevant to the birthing process in other animals such as humans.     

Age‐related modulation of angiogenesis‐regulating factors in the swine meniscus

An in‐depth knowledge of the native meniscus morphology and biomechanics in its different areas is essential to develop an engineered tissue. Meniscus is characterized by a great regional variation in extracellular matrix components and in vascularization. Then, the aim of this work was to characterize the expression of factors involved in angiogenesis in different areas during meniscus maturation in pigs. The menisci were removed from the knee joints of neonatal, young and adult pigs, and they were divided into the inner, intermediate and outer areas. Vascular characterization and meniscal maturation were evaluated by immunohistochemistry and Western blot analysis. In particular, expression of the angiogenic factor Vascular Endothelial Growth Factor (VEGF) and the anti‐angiogenic marker Endostatin (ENDO) was analysed, as well as the vascular endothelial cadherin (Ve‐CAD). In addition, expression of Collagen II (COLL II) and SOX9 was examined, as markers of the fibro‐cartilaginous differentiation. Expression of VEGF and Ve‐CAD had a similar pattern in all animals, with a significant increase from the inner to the outer part of the meniscus. Pooling the zones, expression of both proteins was significantly higher in the neonatal meniscus than in young and adult menisci. Conversely, the young meniscus revealed a significantly higher expression of ENDO compared to the neonatal and adult ones. Analysis of tissue maturation markers showed an increase in COLL II and a decrease in SOX9 expression with age. These preliminary data highlight some of the changes that occur in the swine meniscus during growth, in particular the ensemble of regulatory factors involved in angiogenesis.     

Enhanced inflammation and attenuated tumor suppressor pathways are associated with oncogene‐induced lung tumors in aged mice

Aging is often accompanied by a dramatic increase in cancer susceptibility. To gain insights into how aging affects tumor susceptibility, we generated a conditional mouse model in which oncogenic Kras^G12D was activated specifically in lungs of young (3–5 months) and old (19–24 months) mice. Activation of Kras^G12D in old mice resulted in shorter survival and development of higher‐grade lung tumors. Six weeks after Kras^G12D activation, old lung tissues contained higher numbers of adenomas than their young tissue counterparts. Lung tumors in old mice displayed higher proliferation rates, as well as attenuated DNA damage and p53 tumor suppressor responses. Gene expression comparison of lung tumors from young and old mice revealed upregulation of extracellular matrix‐related genes in young tumors, indicative of a robust cancer‐associated fibroblast response. In old tumors, numerous inflammation‐related genes such as Ccl7, IL‐1β, Cxcr6, and IL‐15ra were consistently upregulated. Increased numbers of immune cells were localized around the periphery of lung adenomas from old mice. Our experiments indicate that more aggressive lung tumor formation in older Kras^G12D mice may be in part the result of subdued tumor suppressor and DNA damage responses, an enhanced inflammatory milieu, and a more accommodating tissue microenvironment.     

Long noncoding RNA THRIL promotes foam cell formation and inflammation in macrophages

Tumor necrosis factor-α (TNF-α) and heterogenous nuclear ribonucleoprotein L (hnRNPL)-related immunoregulatory lincRNA (THRIL) is a long noncoding RNA (lncRNA) involved in various inflammatory diseases. However, its role in atherosclerosis is not known. In this study, we aimed to investigate the function of THRIL in mediating macrophage inflammation and foam cell formation. The expression of THRIL was quantified in THP-1 macrophages after treatment with oxidized low-density lipoprotein (oxLDL). The effect of THRIL overexpression and knockdown on oxLDL-induced inflammatory responses and lipid accumulation was determined. THRIL-associated protein partners were identified by RNA pull-down and RNA immunoprecipitation assays. We show that THRIL is upregulated in macrophages after oxLDL treatment. Knockdown of THRIL blocks oxLDL-induced expression of interleukin-1β (IL-1β), IL-6, and TNF-α and lipid accumulation. Conversely, ectopic expression of THRIL enhances inflammatory gene expression and lipid deposition in oxLDL-treated macrophages. Moreover, THRIL depletion increases cholesterol efflux from macrophages and the expression of ATP-binding cassette transporter (ABC) A1 and ABCG1. FOXO1 is identified as a protein partner of THRIL and promotes macrophage inflammation and lipid accumulation. Furthermore, overexpression of FOXO1 restores lipid accumulation and inflammatory cytokine production in THRIL-depleted macrophages. In conclusion, our data suggest a model where THRIL interacts with FOXO1 to promote macrophage inflammation and foam cell formation. THRIL may represent a therapeutic target for atherosclerosis.     

Age‐associated microRNA expression in human peripheral blood is associated with all‐cause mortality and age‐related traits

Recent studies provide evidence of correlations of DNA methylation and expression of protein‐coding genes with human aging. The relations of microRNA expression with age and age‐related clinical outcomes have not been characterized thoroughly. We explored associations of age with whole‐blood microRNA expression in 5221 adults and identified 127 microRNAs that were differentially expressed by age at P < 3.3 × 10^?4 (Bonferroni‐corrected). Most microRNAs were underexpressed in older individuals. Integrative analysis of microRNA and mRNA expression revealed changes in age‐associated mRNA expression possibly driven by age‐associated microRNAs in pathways that involve RNA processing, translation, and immune function. We fitted a linear model to predict ‘microRNA age’ that incorporated expression levels of 80 microRNAs. MicroRNA age correlated modestly with predicted age from DNA methylation (r = 0.3) and mRNA expression (r = 0.2), suggesting that microRNA age may complement mRNA and epigenetic age prediction models. We used the difference between microRNA age and chronological age as a biomarker of accelerated aging (Δage) and found that Δage was associated with all‐cause mortality (hazards ratio 1.1 per year difference, P = 4.2 × 10^?5 adjusted for sex and chronological age). Additionally, Δage was associated with coronary heart disease, hypertension, blood pressure, and glucose levels. In conclusion, we constructed a microRNA age prediction model based on whole‐blood microRNA expression profiling. Age‐associated microRNAs and their targets have potential utility to detect accelerated aging and to predict risks for age‐related diseases.