Upregulated ex vivo expression of stress-responsive inflammatory pathway genes by LPS-challenged CD14(+) monocytes in frail older adults

A Study of Physical Resilience and Aging (SPRING): Conceptual framework, rationale, and study design

Understanding the physiological basis of physical resilience to clinical stressors is crucial for the well-being of older adults. This article presents a novel framework to discover the biological underpinnings of physical resilience in older adults as part of the "Characterizing Resiliencies to Physical Stressors in Older Adults: A Dynamical Physiological Systems Approach" study, also known as The Study of Physical Resilience and Aging (SPRING). Physical resilience, defined as the capacity of a person to withstand clinical stressors and quickly recover or improve upon a baseline functional level, is examined in adults aged 55 years and older by studying the dynamics of stress response systems. The hypothesis is that well-regulated stress response systems promote physical resilience. The study employs dynamic stimulation tests to assess energy metabolism, the hypothalamic-pituitary-adrenal axis, the autonomic nervous system, and the innate immune system. Baseline characteristics influencing resilience outcomes are identified through deep phenotyping of physical and cognitive function, as well as of biological, environmental, and psychosocial characteristics. SPRING aims to study participants undergoing knee replacement surgery (n = 100), bone and marrow transplantation (n = 100), or anticipating dialysis initiation (n = 60). Phenotypic and functional measures are collected pre-stressor and at multiple times after stressor for up to 12 months to examine resilience trajectories. By improving our understanding of physical resilience in older adults, SPRING has the potential to enhance resilient outcomes to major clinical stressors. The article provides an overview of the study's background, rationale, design, pilot phase, implementation, and implications for improving the health and well-being of older adults.

Are Skeletal Muscle Changes during Prolonged Space Flights Similar to Those Experienced by Frail and Sarcopenic Older Adults?

Microgravity exposure causes several physiological and psychosocial alterations that challenge astronauts' health during space flight. Notably, many of these changes are mostly related to physical inactivity influencing different functional systems and organ biology, in particular the musculoskeletal system, dramatically resulting in aging-like phenotypes, such as those occurring in older persons on Earth. In this sense, sarcopenia, a syndrome characterized by the loss in muscle mass and strength due to skeletal muscle unloading, is undoubtedly one of the most critical aging-like adverse effects of microgravity and a prevalent problem in the geriatric population, still awaiting effective countermeasures. Therefore, there is an urgent demand to identify clinically relevant biological markers and to underline molecular mechanisms behind these effects that are still poorly understood. From this perspective, a lesson from Geroscience may help tailor interventions to counteract the adverse effects of microgravity. For instance, decades of studies in the field have demonstrated that in the older people, the clinical picture of sarcopenia remarkably overlaps (from a clinical and biological point of view) with that of frailty, primarily when referred to the physical function domain. Based on this premise, here we provide a deeper understanding of the biological mechanisms of sarcopenia and frailty, which in aging are often considered together, and how these converge with those observed in astronauts after space flight.

Sex-specific transcriptome differences in a middle-aged frailty cohort

Background

Frailty is a clinical syndrome described as reduced physiological reserve and increased vulnerability. Typically examined in older adults, recent work shows frailty occurs in middle-aged individuals and is associated with increased mortality. Previous investigation of global transcriptome changes in a middle-aged cohort from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study demonstrated inflammatory genes and pathways were significantly altered by frailty status and race. Transcriptome differences in frailty by sex remain unclear. We sought to discover novel genes and pathways associated with sex and frailty in a diverse middle-aged cohort using RNA-Sequencing.

Methods

Differential gene expression and pathway analyses were performed in peripheral blood mononuclear cells for 1) frail females (FRAF, n = 4) vs non-frail females (NORF, n = 4), 2) frail males (FRAM, n = 4) vs non-frail males (NORM, n = 4), 3) FRAM vs FRAF, and 4) NORM vs NORF. We evaluated exclusive significant genes and pathways, as well as overlaps, between the comparison groups.

Results

Over 80% of the significant genes exclusive to FRAF vs NORF, FRAM vs NORM, and FRAM vs FRAF, respectively, were novel and associated with various biological functions. Pathways exclusive to FRAF vs NORF were associated with reduced inflammation, while FRAM vs NORM exclusive pathways were related to aberrant musculoskeletal physiology. Pathways exclusive to FRAM vs FRAF were associated with reduced cell cycle regulation and activated catabolism and Coronavirus pathogenesis.

Conclusions

Our results indicate sex-specific transcriptional changes occur in middle-aged frailty, enhancing knowledge on frailty progression and potential therapeutic targets to prevent frailty.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03326-7.

Biomarkers shared by frailty and sarcopenia in older adults: A systematic review and meta-analysis

BACKGROUND

Physical frailty and sarcopenia show extensive clinical similarities. Whether biomarkers exist that are shared by the two conditions is presently unclear.

METHODS

We conducted a systematic review and meta-analysis of cross-sectional and longitudinal studies that investigated the association of frailty and/or sarcopenia with biomarkers as a primary or secondary outcome in adults aged 60 years and older. Only studies published in English that defined frailty using a validated scale and/or questionnaire and diagnosed sarcopenia according to the presence of muscle atrophy plus dynapenia or low physical function were included. Studies were identified from a systematic search of MEDLINE and SCOPUS databases from inception through August 2020. The quality of reporting of each study was assessed by using the Quality Assessment Tool for Observational Cohort, Cross-Sectional and Case-Control studies of the National Institute of Health. A meta-analysis was conducted when at least three studies investigated the same biomarker in both frailty and sarcopenia. Pooled effect size was calculated based on standard mean differences and random-effect models. Sensitivity analysis was performed based on age and the setting where the study was conducted.

RESULTS

Eighty studies (58 on frailty and 22 on sarcopenia) met the inclusion criteria and were included in the qualitative analysis. Studies on frailty included 33,160 community-dwellers, hospitalized, or institutionalized older adults (60-88 years) from 21 countries. Studies on sarcopenia involved 4904 community-living and institutionalized older adults (68-87.6 years) from 9 countries. Several metabolic, inflammatory, and hematologic markers were found to be shared between the two conditions. Albumin and hemoglobin were negatively associated with both frailty and sarcopenia. Interleukin 6 was associated with frailty and sarcopenia only in people aged < 75. Community-dwelling older adults with frailty and sarcopenia had higher levels of tumor necrosis factor alpha compared with their robust and non-sarcopenic counterparts.

CONCLUSIONS

A set of metabolic, hematologic, and inflammatory biomarkers was found to be shared by frailty and sarcopenia. These findings fill a knowledge gap in the quest of biomarkers for these conditions and provide a rationale for biomarker selection in studies on frailty and sarcopenia.

Research progress of gut microbiota and frailty syndrome

Frailty is a clinical syndrome caused by homeostasis imbalance. It is characterized by marked vulnerability to endogenous or exogenous stressors, reduced self-care ability, and increased mortality risk. This aging-related syndrome is common in individuals older than 65 years and carries an increased risk for poor health outcomes. These include falls, incident disability, incapacity, and mortality. In addition, it can result in a poor prognosis for other comorbidities. With the aging population, frailty increases the burden of adverse health outcomes. Studies on frailty are at their infancy. In addition, there is a lack of thorough understanding of its pathogenesis. Several studies have suggested that frailty is caused by chronic inflammation due to enhanced intestinal permeability following gut microbiota imbalance as well as pathogen-related antibodies entering the circulation system. These result in musculoskeletal system disorders and neurodegenerative diseases. However, this assumption has not been validated in large cohort-based studies. Several studies have suggested that inflammation is not the only cause of frailty. Hence, further studies are necessary to extend our understanding of its pathogenesis. This review summarizes the research findings in the field and expands on the possible role of the gut microbiota in frailty syndrome.

Fostering healthy aging: The interdependency of infections, immunity and frailty

Untangling the interdependency of infections, immunity and frailty may help to clarify their roles in the maintenance of health in aging individuals, and the recent COVID-19 pandemic has further highlighted such priority. In this scoping review we aimed to systematically collect the evidence on 1) the impact of common infections such as influenza, pneumonia and varicella zoster on frailty development, and 2) the role played by frailty in the response to immunization of older adults. Findings are discussed under a unifying framework to identify knowledge gaps and outline their clinical and public health implications to foster a healthier aging. Twenty-nine studies (113,863 participants) selected to answer the first question provided a moderately strong evidence of an association between infections and physical as well as cognitive decline - two essential dimensions of frailty. Thirteen studies (34,520 participants) investigating the second aim, showed that frailty was associated with an impaired immune response in older ages, likely due to immunosenescence. However, the paucity of studies, the absence of tools to predict vaccine efficacy, and the lack of studies investigating the efficacy of newer vaccines in presence of frailty, strongly limit the formulation of more personalized immunization strategies for older adults. The current evidence suggests that infections and frailty repeatedly cross each other pathophysiological paths and accelerate the aging process in a vicious circle. Such evidence opens to several considerations. First, the prevention of both conditions pass through a life course approach, which includes several individual and societal aspects. Second, the maintenance of a well-functioning immune system may be accomplished by preventing frailty, and vice versa. Third, increasing the adherence to immunization may delay the onset of frailty and maintain the immune system homeostasis, beyond preventing infections.

The impact of ageing on monocytes and macrophages

Ageing is a global burden. Increasing age is associated with increased incidence of infections and cancer and decreased vaccine efficacy. This increased morbidity observed with age, is believed to be due in part to a decline in adaptive immunity, termed immunosenescence. However not all aspects of immunity decrease with age as ageing presents with systemic low grade chronic inflammation, characterised by elevated concentrations of mediators such as IL-6, TNFα and C Reactive protein (CRP). Inflammation is a strong predictor of morbidity and mortality, and chronic inflammation is known to be detrimental to a functioning immune system. Although the source of the inflammation is much discussed, the key cells which are believed to facilitate the inflammageing phenomenon are the monocytes and macrophages. In this review we detail how macrophage and monocyte phenotype and function change with age. The impact of ageing on macrophages includes decreased phagocytosis and immune resolution, increased senescent-associated markers, increased inflammatory cytokine production, reduced autophagy, and a decrease in TLR expression. With monocytes there is an increase in circulating CD16⁺ monocytes, decreased type I IFN production, and decreased efferocytosis. In conclusion, we believe that monocytes and macrophages contribute to immunosenescence and inflammageing and as a result have an important role in defective immunity with age.

Immunity to acute virus infections with advanced age

New infections in general, and new viral infections amongst them, represent a serious challenge to an older organism. This review discusses the age-related alterations in responsiveness to infection from the standpoint of virus:host relationship and the host physiological whole-organism and specific immune response to the virus. Changes with age in the innate and adaptive immune system homeostasis and function are reviewed briefly. This is followed by a review of specific alterations and defects in the response of older organisms (chiefly mice and humans) to acute (particularly emerging and re-emerging) viral infections, with a very brief summary of the response to latent persistent infections. Finally, we provide a brief summary of the perspectives for possible interventions to enhance antiviral immunity.

Discovery, development, and future application of senolytics: theories and predictions

Senescent cells accumulate with aging and at etiological sites of multiple diseases, including those accounting for most morbidity, mortality, and health costs. Senescent cells do not replicate, can release factors that cause tissue dysfunction, and yet remain viable. The discovery of senolytic drugs, agents that selectively eliminate senescent cells, created a new route for alleviating age‐related dysfunction and diseases. As anticipated for agents targeting fundamental aging mechanisms that are ‘root cause’ contributors to multiple disorders, potential applications of senolytics are protean. We review the discovery of senolytics, strategies for translation into clinical application, and promising early signals from clinical trials.

Tinnitus, hearing loss and inflammatory processes in an older Portuguese population

Objective: Tinnitus is associated with various conditions such as presbycusis, infectious, autoimmune and many other diseases. Our study aims to identify an association between inflammatory markers and the presence of tinnitus or hearing loss (HL).Design: Exploratory study including a structured interview, complete ENT observation, audiological and inflammatory markers evaluation.Study Sample: Sixty women and 54 men (55 to 75 years) from the Portuguese population, with or without sensory presbycusis and/or tinnitus.Results: IL10 levels were significantly lower in participants with tinnitus than in those without tinnitus. Moreover, TGF-β was lower in older participants (p = 0.034), IL1α was higher in participants with tonal tinnitus (p = 0.033), and IL2 was lower in participants who reported partial or complete residual inhibition (p = 0.019). Additionally, we observed a negative correlation between tinnitus duration and IL10 levels (r= -.281), and between HSP70 levels and tinnitus loudness (r= -.377). TNF-α and HSP70 levels appears to be sensitive to the time when samples were collected (morning or afternoon).Conclusions: The results of our study showing fluctuations in inflammatory markers along the hearing loss process, reinforce the idea that inflammatory mechanisms are involved in hearing loss pathogenesis but also in tinnitus. IL10 levels appear significantly altered in tinnitus but not in hearing loss.

Aging, sex, inflammation, frailty, and CMV and HIV infections

Aging is characterized by significant immune remodeling at both cellular and molecular levels, also known as immunosenescence. Older adults often manifest a chronic low-grade inflammatory phenotype. These age-related immune system changes have increasingly been recognized not only to lead to immune functional decline and increased vulnerability to infections, but also to play an important role in many chronic conditions such as frailty in older adults. In addition to sex as an important biological factor, chronic viral infections including that by human immunodeficiency virus (HIV) and cytomegalovirus (CMV) are all known to have major impact on the aging immune system. This article provides an overview of our current understanding of aging immunity, sex, inflammation, frailty, and HIV and CMV infections.

Inflammatory Pathways to Anemia in the Frail Elderly

Anemia is a common, yet often overlooked, geriatric syndrome characterized by reduced hemoglobin levels and associated with adverse health outcomes and early mortality. Evidence suggests that anemia is an independent risk factor for frailty in older adults. In this article, the authors review the evidence for the role of chronic inflammation in the pathogenesis of anemia in the frail elderly. Understanding the relationships between anemia, frailty, and chronic inflammation will pave the way for the development of novel interventional strategies for the treatment and prevention of anemia and, likely, also frailty in older adults.

Chronic Low-grade Inflammatory Phenotype (CLIP) and Senescent Immune Dysregulation

PURPOSE

The aim was to provide an overview of chronic low-grade inflammatory phenotype (CLIP) and evidence for its role in the pathogenesis of frailty and other chronic conditions as well as potential causative factors and interventions.

METHODS

We reviewed evidence from published clinical and laboratory studies and summarized the opinions of experts from published reviews.

FINDINGS

CLIP is a low-grade, systemic, unresolved, and smoldering chronic inflammatory state clearly indicated by a 2- to 4-fold increase in serum levels of inflammatory mediators, such as interleukin-6 and C-reactive protein. It involves many other cellular and molecular inflammatory mediators. CLIP typically occurs during aging, also known as "inflammaging," and is an integral part of the spectrum of immunosenescence. Causative factors likely include persistent viral infections, particularly chronic cytomegalovirus infection, cellular senescence, failure to eliminate degraded materials and waste products, dysregulated microbiota and gut permeability, obesity, and others. Substantial evidence supports CLIP as a powerful contributing factor to frailty and many other chronic conditions and adverse health outcomes. Many of the inflammatory mediators and their regulatory mechanisms in CLIP may serve as potential targets for therapeutic intervention. However, development of new interventional strategies for CLIP and its associated chronic conditions should take the complexity of the inflammatory network into consideration. Nonpharmacologic interventions, such as caloric restriction and exercise, may have significant impact on CLIP and its causative factors, leading to substantial health benefits. Metformin and resveratrol have anti-inflammatory property and may serve as a promising therapeutic agent for treatment of CLIP and frailty.

IMPLICATIONS

CLIP is a chronic inflammatory pathophysiologic process that plays an important role in the pathogenesis of frailty and many other chronic conditions. Improving our understanding of this phenotype may provide opportunities to identify potential targets of effective prevention and therapeutic strategies for frailty and other CLIP-associated conditions.

Influence of Aging and Environment on Presentation of Infection in Older Adults

In older adults, pathophysiologic, clinical, and environmental factors all affect the presentation of infections. We explore how age-related changes influence the manifestation and evaluation of infections in this population. Specific topics include immunosenescence, age-related organ-specific physiologic changes, and frailty. We also describe clinical factors influencing infection risk and presentation in older adults, including temperature regulation, cognitive decline, and malnutrition. Finally, we discuss the influence of the setting in which older adults reside on the clinical evaluation of infection. Understanding the influence of all these changes may facilitate the prevention, early recognition, and treatment of infections in older adults.

The Biology of Aging and Cancer: Frailty, Inflammation, and Immunity

The majority of patients with common malignancies are older adults. Intrinsic complex biological changes of aging along with inflammation, immunosenescence, age-associated chronic diseases, and extrinsic environmental and psychosocial factors have significant impact on not only development and behavior of individual malignancies, but also physiologic reserve and vulnerability of older patients who suffer from them. As a result, clinical practice of geriatric oncology demands integration of careful geriatric assessment and management. This article provides an overview of basic biology of aging and its relationship with cancer. After a brief introduction about the definition and mechanisms of aging, as well as age-related biological and physiological changes, the discussion mainly focuses on recent development and insights into the relationship of frailty, inflammation, and immunity with cancer, highlighting how the new knowledge can help further improve assessment and treatment of older patients with malignancies and promote cancer research.

Frailty Status in Older Adults Is Related to Alterations in Indoleamine 2,3-Dioxygenase 1 and Guanosine Triphosphate Cyclohydrolase I Enzymatic Pathways

BACKGROUND

Frailty is a multidimensional syndrome correlated to the loss of homeostasis and increased vulnerability to stressors, which is associated with increase in the risk of disability, comorbidity, hospitalization, and death in the elderly. It is based on the interplay of physiological, psychological, social, and environmental factors.

OBJECTIVES

Because aging involves a detrimental immune response, this work aimed to assess the possible role of chronic low-grade immune stimulation on frailty status in the elderly.

METHODS

Biomarkers involved in indoleamine 2,3-dioxygenase 1 and guanosine triphosphate cyclohydrolase I enzymatic pathways (namely neopterin, tryptophan, kynurenine, phenylalanine, tyrosine, and nitrite) were analyzed in a population of Spanish older adults aged 65 years and above, and their relationships with frailty status were evaluated.

RESULTS

Significant increases in neopterin levels, kynurenine/tryptophan ratio, and phenylalanine/tyrosine ratio, and significant decreases in tryptophan, nitrite and tyrosine concentrations in frail individuals compared with nonfrail persons were obtained. Significant correlations were also observed between immune biomarkers, indicating they change in parallel, thus, pointing to interrelated causes. Besides, reference ranges for a number of immune biomarkers in the population of robust older adults were established for the first time.

CONCLUSIONS

Results obtained in the present study are consistent with the idea that frailty status in the elderly is associated with an additional degree of immune stimulation, manifested in a more intense disturbance of indoleamine 2,3-dioxygenase 1 and guanosine triphosphate cyclohydrolase I pathways than in nonfrail or prefrail older adults.

Frailty and sarcopenia as the basis for the phenotypic manifestation of chronic diseases in older adults

Frailty is a functional status that precedes disability and is characterized by decreased functional reserve and increased vulnerability. In addition to disability, the frailty phenotype predicts falls, institutionalization, hospitalization and mortality. Frailty is the consequence of the interaction between the aging process and some chronic diseases and conditions that compromise functional systems and finally produce sarcopenia. Many of the clinical manifestations of frailty are explained by sarcopenia which is closely related to poor physical performance. Reduced regenerative capacity, malperfusion, oxidative stress, mitochondrial dysfunction and inflammation compose the sarcopenic skeletal muscle alterations associated to the frailty phenotype. Inflammation appears as a common determinant for chronic diseases, sarcopenia and frailty. The strategies to prevent the frailty phenotype include an adequate amount of physical activity and exercise as well as pharmacological interventions such as myostatin inhibitors and specific androgen receptor modulators. Cell response to stress pathways such as Nrf2, sirtuins and klotho could be considered as future therapeutic interventions for the management of frailty phenotype and aging-related chronic diseases.

Translating the Science of Aging into Therapeutic Interventions

Life and health span have been extended in experimental animals using drugs that are potentially translatable into humans. Considerable effort is needed beyond the usual steps in drug development to devise the models, and realistic preclinical and clinical trial strategies are required to advance these agents into clinical application. It will be important to focus on subjects who already have symptoms or are at imminent risk of developing disorders related to fundamental aging processes, to use short-term, clinically relevant outcomes, as opposed to long-term outcomes, such as health span or life span, and to validate endpoint measures so they are acceptable to regulatory agencies. Funding is a roadblock, as is shortage of investigators with combined expertise in the basic biology of aging, clinical geriatrics, and investigational new drug clinical trials. Strategies for developing a path from the bench to the bedside are reviewed for interventions that target fundamental aging mechanisms.

TNF Drives Monocyte Dysfunction with Age and Results in Impaired Anti-pneumococcal Immunity

Monocyte phenotype and output changes with age, but why this occurs and how it impacts anti-bacterial immunity are not clear. We found that, in both humans and mice, circulating monocyte phenotype and function was altered with age due to increasing levels of TNF in the circulation that occur as part of the aging process. Ly6C⁺ monocytes from old (18–22 mo) mice and CD14⁺CD16⁺ intermediate/inflammatory monocytes from older adults also contributed to this “age-associated inflammation” as they produced more of the inflammatory cytokines IL6 and TNF in the steady state and when stimulated with bacterial products. Using an aged mouse model of pneumococcal colonization we found that chronic exposure to TNF with age altered the maturity of circulating monocytes, as measured by F4/80 expression, and this decrease in monocyte maturation was directly linked to susceptibility to infection. Ly6C⁺ monocytes from old mice had higher levels of CCR2 expression, which promoted premature egress from the bone marrow when challenged with Streptococcus pneumoniae. Although Ly6C⁺ monocyte recruitment and TNF levels in the blood and nasopharnyx were higher in old mice during S. pneumoniae colonization, bacterial clearance was impaired. Counterintuitively, elevated TNF and excessive monocyte recruitment in old mice contributed to impaired anti-pneumococcal immunity since bacterial clearance was improved upon pharmacological reduction of TNF or Ly6C⁺ monocytes, which were the major producers of TNF. Thus, with age TNF impairs inflammatory monocyte development, function and promotes premature egress, which contribute to systemic inflammation and is ultimately detrimental to anti-pneumococcal immunity.

As we age, levels of inflammatory cytokines in the blood and tissues increase. Although this appears to be an inevitable part of aging, it ultimately contributes to declining health. Epidemiological studies indicate that older adults with higher than age-average levels of inflammatory cytokines are at increased risk of acquiring, becoming hospitalized with and dying of Streptococcus pneumoniae pneumonia but how age-associated inflammation increased susceptibility to was not entirely clear. We demonstrate that the increase in the inflammatory cytokine TNF that occurs with age cause monocytes to leave the bone marrow prematurely and these immature monocytes produce more inflammatory cytokines when stimulated with bacterial products, thus further increasing levels of inflammatory cytokines in the blood. Furthermore, although old mice have higher levels of these inflammatory monocytes arriving at the site of S. pneumoniae, they are not able to clear the bacteria. By pharmacologically or genetically removing the inflammatory cytokine TNF or reducing the number of inflammatory monocytes we were able to restore antibacterial immunity in aged mice. Thus we demonstrate that monocytes are both influenced by and contributors to age-associated inflammation and that chronic exposure to age-associated inflammation increases susceptibility to S. pneumoniae due to altering monocyte maturity and function.

Frailty predictors and outcomes among older patients with cardiovascular disease: Data from Fragicor

The aim of this study was to evaluate predictive factors for frailty among older outpatient adults with cardiovascular disease (CVD) and to assess the predictive value of frailty in regard to mortality, disability and hospitalization at 1-year follow-up. A prospective cohort study was carried out with subjects over 65 years of age from an outpatient Cardiology clinic, with at least one CVD. At baseline, we classified frailty as proposed by Fried, i.e.; unintentional weight loss (10lbs in the past year), self-reported exhaustion, weakness (measured by grip strength), slow walking speed, and low physical activity. A frail person was defined by the presence of three or more criteria, prefrail by one or two and robust by the absence of them. Disability, previous hospitalizations, falls, morphometric and socio-demographic variables were collected; as well as the presence of CVD and hemodynamic parameters (HP): systolic (SPB) and diastolic blood pressure (DBP), heart rate (HR) and ejection fraction (EF). At 1-year follow-up, the outcomes assessed were: disability, number of hospitalizations and death. 172 subjects were included in this study with a mean age of 77 years old. The prevalence of frail was 39.8%, prefrail 51.5% and robust was 8.7%. Among the CVD and HP evaluated, myocardial infarction (MI), presence of three or more CVDs, lower SPB and DBP were significant and independent factors associated with the frailty phenotype. At 1-year follow up, frailty was an independent predictor for disability (Odds Ratio (OR): 3.94 (1.59-9.75); p=0.003) and it increased death probability by three times if compared to the robust group. In conclusion, older outpatients with CVD have a higher probability to be frail than older adults who do not have a CVD. Low SPB and DBP must always be taken into consideration due to their high association with frailty. It is also important to diagnose frailty in this population due to the high association with mortality and disability.

Understanding frailty, aging, and inflammation in HIV infection

Frailty is a clinical syndrome initially characterized in geriatric populations with a hallmark of age-related declines in physiologic reserve and function and increased vulnerability to adverse health outcomes. Recently, frailty has increasingly been recognized as a common and important HIV-associated non-AIDS (HANA) condition. This article provides an overview of our current understanding of frailty and its phenotypic characteristics and evidence that they are related to aging and to chronic inflammation that is associated with aging and also with long-term treated HIV infection. The etiology of this chronic inflammation is unknown but we discuss evidence linking it to persistent infection with cytomegalovirus in both geriatric populations and people living with HIV infection.

Clinical strategies and animal models for developing senolytic agents

Aging is associated with increasing predisposition to multiple chronic diseases. One fundamental aging process that is often operative at sites of the pathology underlying chronic age-related diseases is cellular senescence. Small molecule senolytic agents are being developed. For successful drug development: 1) appropriate animal models of human age-related diseases need to be devised. 2) Models have to be made in which it can be proven that beneficial phenotypic effects are actually caused through clearing senescent cells by putative senolytic agents, as opposed to "off-target" effects of these agents on non-senescent cells. 3) Models are needed to test efficacy of drugs and to uncover potential side effects of senolytic agents. Development of the optimal animal models and clinical trial paradigms for senolytic agents warrants an intensive effort, since senolytic agents, if successful in delaying, preventing, alleviating, or reversing age-related diseases as a group would be transformative.

Frailty syndrome: an overview

Frailty is a common and important geriatric syndrome characterized by age-associated declines in physiologic reserve and function across multiorgan systems, leading to increased vulnerability for adverse health outcomes. Two major frailty models have been described in the literature. The frailty phenotype defines frailty as a distinct clinical syndrome meeting three or more of five phenotypic criteria: weakness, slowness, low level of physical activity, self-reported exhaustion, and unintentional weight loss. The frailty index defines frailty as cumulative deficits identified in a comprehensive geriatric assessment. Significant progress has recently been made in understanding the pathogenesis of frailty. Chronic inflammation is likely a key pathophysiologic process that contributes to the frailty syndrome directly and indirectly through other intermediate physiologic systems, such as the musculoskeletal, endocrine, and hematologic systems. The complex multifactorial etiologies of frailty also include obesity and specific diseases. Major clinical applications include risk assessment and stratification. This can be applied to the elderly population in the community and in a variety of care settings. Frailty may also be useful for risk assessment in surgical patients and those with cardiovascular diseases, cancer, or human immunodeficiency virus infection, as well as for assessment of vaccine effectiveness in older adults. Currently, exercise and comprehensive geriatric interdisciplinary assessment and treatment are key interventions for frailty. As understanding of the biologic basis and complexity of frailty further improves, more effective and targeted interventional strategies and innovative geriatric-care models will likely be developed.

Frailty in elderly people

Frailty is the most problematic expression of population ageing. It is a state of vulnerability to poor resolution of homoeostasis after a stressor event and is a consequence of cumulative decline in many physiological systems during a lifetime. This cumulative decline depletes homoeostatic reserves until minor stressor events trigger disproportionate changes in health status. In landmark studies, investigators have developed valid models of frailty and these models have allowed epidemiological investigations that show the association between frailty and adverse health outcomes. We need to develop more efficient methods to detect frailty and measure its severity in routine clinical practice, especially methods that are useful for primary care. Such progress would greatly inform the appropriate selection of elderly people for invasive procedures or drug treatments and would be the basis for a shift in the care of frail elderly people towards more appropriate goal-directed care.

Cellular senescence and the senescent secretory phenotype: therapeutic opportunities

Aging is the largest risk factor for most chronic diseases, which account for the majority of morbidity and health care expenditures in developed nations. New findings suggest that aging is a modifiable risk factor, and it may be feasible to delay age-related diseases as a group by modulating fundamental aging mechanisms. One such mechanism is cellular senescence, which can cause chronic inflammation through the senescence-associated secretory phenotype (SASP). We review the mechanisms that induce senescence and the SASP, their associations with chronic disease and frailty, therapeutic opportunities based on targeting senescent cells and the SASP, and potential paths to developing clinical interventions.

Blood CD33(+)HLA-DR(-) myeloid-derived suppressor cells are increased with age and a history of cancer

Myeloid-derived suppressor cells are increased with age and elevated in donors with a history of cancer; an age-related effect has never been shown in humans.

As we age, the composition of our peripheral leukocytes changes dramatically. Many of these alterations contribute to the general immune dysfunction that burdens the elderly, which in turn, contributes to increased susceptibility to disease. MDSCs represent a heterogeneous population of immunosuppressive leukocytes that are elevated in the peripheral blood of cancer patients. Given the relation between cancer incidence and age, this study examined the frequency of peripheral blood CD33(+)HLA-DR(−) MDSCs across three cohorts: healthy adults (19–59 years old), community-dwelling seniors (61–76 years old), and frail elderly (67–99 years old). This analysis is the first to demonstrate that MDSCs and specifically the CD11b(+)CD15(+) MDSC subset are increased with age. Proinflammatory cytokines that are required for the differentiation of MDSCs (e.g., TNF-α, IL-6, and IL-1β) were similarly found to be increased in the serum of the frail elderly. Furthermore, the proportion of MDSCs and the CD11b(+)CD15(+) subset were found to be elevated significantly in elderly donors with a history of cancer. This age-related elevation in the frequency of MDSCs may contribute to the increased cancer incidence that occurs with age. Further investigation into the functional consequences of elevated MDSCs will provide valuable insight into the progression of age-related pathologies.

Translating advances from the basic biology of aging into clinical application

Recently, lifespan and healthspan have been extended in experimental animals using interventions that are potentially translatable into humans. A great deal of thought and work is needed beyond the usual steps in drug development to advance these findings into clinical application. Realistic pre-clinical and clinical trial paradigms need to be devised. Focusing on subjects with symptoms of age-related diseases or frailty or who are at imminent risk of developing these problems, measuring effects on short-term, clinically relevant outcomes, as opposed to long-term outcomes such as healthspan or lifespan, and developing biomarkers and outcome measures acceptable to regulatory agencies will be important. Research funding is a major roadblock, as is lack of investigators with combined expertise in the basic biology of aging, clinical geriatrics, and conducting investigational new drug clinical trials. Options are reviewed for developing a path from the bench to the bedside for interventions that target fundamental aging processes.

The frailty syndrome: a comprehensive review

The frailty syndrome is defined as unintentional weight and muscle loss, exhaustion, and declines in grip strength, gait speed, and activity. Evidence with respect to the clinical definition, epidemiology, mechanisms, interactions, assessment, prevention, and treatment of frailty in the older adult is reviewed.

Frailty, inflammation, and immunity

Frailty is an important geriatric syndrome that is characterized by multisystem dysregulation, leading to decreased physiological reserve and increased vulnerability for adverse health outcomes. A large number of studies have shown a heightened inflammatory state marked by elevated levels of inflammatory molecules, such as IL-6 and C-reactive protein (CRP), and increased counts of white blood cell (WBC) and WBC subpopulations in frail older adults. It has been postulated that this heightened inflammatory state, or chronic inflammation, may play an important role in the pathogenesis of frailty, directly or through its detrimental influence to other physiologic systems. Inflammatory and immune activation mediated by monocytes and macrophages demonstrated by upregulated expression of specific stress responsive inflammatory pathway genes and elevated neopterin levels may contribute, at least in part, to this chronically heightened inflammatory state in frailty. Decrease in lipopolysaccharide (LPS)-induced proliferation of the peripheral blood mononuclear cells (PBMCs), one of the functional readouts of the innate immune system, has also been observed in frail older adults. In the adaptive immune system, significant frailty-associated alterations have been identified in the T-cell compartment including expansion of CD8(+) and CCR5(+) T cells and loss of CD28 expression, above and beyond age-related senescent remodeling. Moreover, frailty is associated with impaired antibody responses to pneumococcal and influenza immunization and poor clinical protection against influenza infection in community-dwelling older adults. Taken together, these findings demonstrate significant inflammatory and immune dysregulation in frail older adults and highlight the need for strategies to improve the immune function for this vulnerable elderly population.

Relationship between cytomegalovirus (CMV) IgG serology, detectable CMV DNA in peripheral monocytes, and CMV pp65(495-503)-specific CD8+ T cells in older adults

In immunocompetent individuals, cytomegalovirus (CMV) is thought to persist in a latent state in monocytes and myeloid progenitor cells, establishing a lifelong infection. In CMV-seropositive older adults, aging has been associated with both expansion of CMV pp65(495-503)-specific CD8(+) T cell clones and shrinkage of the T cell repertoire that characterize T cell immunosenescence. In fact it has been suggested that chronic CMV infection is a driving force in age-related T cell immunosenescence. In older adults, chronic CMV infection is conventionally diagnosed by positive IgG serology which does not distinguish between past and persistent infections. To better define the relationship between chronic CMV infection and expansion of CMV pp65(495-503)-specific CD8(+) T cells, we directly assessed CMV viral DNA in monocyte-enriched peripheral blood mononuclear cells in 16 HLA-A2-positive elderly volunteers (mean age = 83 years). While all participants had positive CMV IgG serology by enzyme-linked immunosorbent assays, only nine (56%) had detectable CMV DNA by nested polymerase chain reaction. These nine individuals had significantly higher percentages of CMV pp65(495-503) tetramer-positive CD8(+) T cells (median = 1.3%) than those without detectable CMV DNA (median = 0.1%; p < 0.001). Absolute CMV IgG antibody titers did not differ between these two groups (median = 54.6 vs 44.2 EU/ml, respectively, p = 0.4). CMV IgM titers were negative for all 16 participants, suggesting that recent primary CMV infection was unlikely. These results demonstrate a strong association between the presence of CMV DNA in peripheral monocytes and the expansion of CD8(+) T cells specific for the CMV immunodominant epitope pp65(495-503). Although the sample size in this study is relatively small, these findings provide initial evidence suggesting the heterogeneity of CMV IgG-seropositive older adult population and CMV viral DNA detection in peripheral monocytes as an informative tool to better understand the relationship between chronic CMV infection and T cell immunosenescence.

Frailty is associated with impairment of vaccine-induced antibody response and increase in post-vaccination influenza infection in community-dwelling older adults

Annual immunization with a trivalent inactivated vaccine (TIV) is considered efficacious for prevention of seasonal influenza in older adults. However, significant controversy exists in the current literature regarding the clinical effectiveness of TIV immunization in this highly heterogeneous population. Frailty is an important geriatric syndrome characterized by decreased physiologic reserve and increased vulnerability to stressors. Using a validated set of frailty criteria, we conducted a prospective observational study to evaluate TIV-induced strain-specific hemagglutination inhibition (HI) antibody titers and post-vaccination rates of influenza-like illness (ILI) and infection in frail and nonfrail older adults. The results indicate that frailty was associated with significant impairment in TIV-induced strain-specific HI titers and increased rates of ILI and laboratory-confirmed influenza infection. These findings suggest that assessing frailty status in the elderly may identify those who are less likely to respond to TIV immunization and be at higher risk for seasonal influenza and its complications.

Dysregulation of human Toll-like receptor function in aging

Studies addressing immunosenescence in the immune system have expanded to focus on the innate as well as the adaptive responses. In particular, aging results in alterations in the function of Toll-like receptors (TLRs), the first described pattern recognition receptor family of the innate immune system. Recent studies have begun to elucidate the consequences of aging on TLR function in human cohorts and add to existing findings performed in animal models. In general, these studies show that human TLR function is impaired in the context of aging, and in addition there is evidence for inappropriate persistence of TLR activation in specific systems. These findings are consistent with an overarching theme of age-associated dysregulation of TLR signaling that likely contributes to the increased morbidity and mortality from infectious diseases found in geriatric patients.

IL-6-independent association of elevated serum neopterin levels with prevalent frailty in community-dwelling older adults

BACKGROUND

neopterin is a monocyte/macrophage-derived immune activation marker and its levels increase with age. Frailty is an important clinical syndrome of old age. Previous studies have shown significant association between elevated interleukin-6 (IL-6) levels and frailty. The objective of this study was to evaluate IL-6-independent association of serum neopterin levels with prevalent frailty.

METHODS

this is a cross-sectional study in community-dwelling older adults recruited from residential and retirement communities in Baltimore, MD, USA. Frailty was determined using validated screening criteria. Serum neopterin and IL-6 levels were measured using standard enzyme-linked immunosorbent assay. Pearson correlation and multivariate linear regression analysis was performed to assess the relationship between log(neopterin) and log(IL-6). Odds ratios (ORs) for frailty were calculated using log(neopterin) and log(IL-6) as continuous measures and across tertiles of neopterin and IL-6 levels, adjusting for age, race, sex, education and body mass index.

RESULTS

one hundred and thirty-three individuals with a mean age of 84 years (range 72-97) completed the study. Neopterin levels were significantly higher in frail older adults than those in non-frail controls [median: 8.94 versus 8.35 nM, respectively, P < 0.001 t-test on log(neopterin)]. Log(neopterin) was significantly associated with prevalent frailty, adjusting for log(IL-6). Participants in the top tertile of neopterin had OR of 3.80 [95% confidence interval (CI) = 1.36-10.6, P < 0.01] for frailty. As expected, participants in the top tertile of IL-6 had OR of 3.29 (95% CI = 1.21-7.86, P < 0.05) for frailty. Log(neopterin) correlated with log(IL-6) (correlation coefficient = 0.19, P < 0.05). Moreover, OR for participants in the top neopterin tertile remained significant after adjusting for IL-6 (OR = 3.97, 95% CI = 1.15-13.72, P < 0.05).

CONCLUSION

elevated neopterin levels had IL-6-independent association with prevalent frailty, suggesting potential monocyte/macrophage-mediated immune activation in the frail elderly.

Association of detectable cytomegalovirus (CMV) DNA in monocytes rather than positive CMV IgG serology with elevated neopterin levels in community-dwelling older adults

In immunocompetent persons, cytomegalovirus (CMV) is thought to persist primarily in monocytes and myeloid progenitor cells, establishing a chronic infection. In older adults, chronic CMV infection is typically diagnosed by a positive IgG serology. While many studies have shown CMV-specific T-cell expansion in CMV seropositive older individuals, significant heterogeneity has also been observed in this elderly population. In a study of 71 community-dwelling older adults, we assessed CMV viral DNA in peripheral monocytes by nested PCR and compared the relationships of detectable CMV DNA and IgG serology with serum levels of neopterin, a marker for monocyte/macrophage-mediated immune activation. The results showed that 52 (73.2%) participants were CMV seropositive, of whom 30 (57.5%) had detectable CMV DNA. CMV seropositive and seronegative participants did not differ in their neopterin levels, but individuals with detectable CMV DNA had higher neopterin than those without (10.6 ± 4.4 vs 8.0 ± 1.9 nM, respectively, p<.0001) adjusting for demographic and clinical covariates and interferon (IFN)-γ levels. In addition, there was no association between IgG titers and neopterin. These findings suggest that detection of CMV viral DNA in monocytes may be an informative tool to evaluate chronic CMV infection and its potential role in monocyte/macrophage-mediated immune activation in the elderly.

Acute kidney injury in older adults

Aging kidneys undergo structural and functional changes that decrease autoregulatory capacity and increase susceptibility to acute injury. Acute kidney injury associates with duration and location of hospitalization, mortality risk, progression to chronic kidney disease, and functional status in daily living. Definition and diagnosis of acute kidney injury are based on changes in creatinine, which is an inadequate marker and might identify patients when it is too late. The incidence of acute kidney injury is rising and increases with advancing age, yet clinical studies have been slow to address geriatric issues or the heterogeneity in etiologies, outcomes, or patient preferences among the elderly. Here we examine some of the current literature, identify knowledge gaps, and suggest potential research questions regarding acute kidney injury in older adults. Answering these questions will facilitate the integration of geriatric issues into future mechanistic and clinical studies that affect management and care of acute kidney injury.

Inflammation and immune system alterations in frailty

Frailty is an important geriatric syndrome characterized by multisystem dysregulation. Substantial evidence suggests heightened inflammatory state and significant immune system alterations in frailty. A heightened inflammatory state is marked by increases in levels of inflammatory molecules (interleukin 6 and C-reactive protein) and counts of white blood cell and its subpopulations, which may play an important role in the pathogenesis of frailty, directly or through its detrimental influence on other physiologic systems. Alterations in the innate immune system include decreased proliferation of the peripheral blood mononuclear cells and upregulated monocytic expression of specific stress-responsive inflammatory pathway genes. In the adaptive immune system, although little information is available about potential B-cell changes, significant alterations have been identified in the T-cell compartment, including increased counts of CD8+, CD8+CD28-, CCR5+T cells, above and beyond age-related senescent immune remodeling.

Associations of neutrophil and monocyte counts with frailty in community-dwelling disabled older women: results from the Women's Health and Aging Studies I

Frailty is an important geriatric syndrome that predicts disability and mortality. Substantial evidence suggests that inflammation marked by elevated IL-6 levels and total white blood cell (WBC) counts contribute to this syndrome. However, the relationships of WBC subpopulations, the important inflammatory and immune cells, with frailty have not been investigated. To address this important question, we conducted cross-sectional polytomous logistic regression analyses evaluating associations between baseline WBC differential counts and prevalent frailty (defined by the validated Fried's criteria) of 558 disabled women aged 65-101 years and 548 women aged 70-79 living in the community, both from the Women's Health and Aging Studies. The results showed that high neutrophil and monocyte counts were associated with frailty in disabled older women, albeit these associations did not reach statistical significance in women aged 70-79, adjusting for age, race, education, body mass index, smoking, and antibiotic use. In addition, the identified associations were independent of IL-6. No significant associations of lymphocyte, eosinophil, or basophil counts with frailty were observed. These findings provide initial insight into potential roles of neutrophils and monocytes in the pathogenesis of frailty and a basis for further investigation into their function and regulation in frail older women.

Upregulated monocytic expression of CXC chemokine ligand 10 (CXCL-10) and its relationship with serum interleukin-6 levels in the syndrome of frailty

Frailty is an important geriatric syndrome that predicts disability and mortality. Substantial evidence suggests inflammation marked by elevated IL-6 levels as a key pathophysiologic factor that contributes to frailty. CXCL-10, a potent pro-inflammatory chemokine, has increased levels with age and is implicated in several inflammatory conditions. To better understand molecular mechanisms of inflammation activation in frailty, we evaluated monocytic expression of CXCL-10 and other inflammatory pathway genes by pathway-specific gene array analysis and quantitative RT-PCR. Frailty status was determined by the validated criteria. Sixteen pairs of community-dwelling frail and age-, race-, and sex-matched non-frail participants (mean age 83 years, range 72-94) completed the study. Here we report that frail participants had higher CXCL-10 expression levels than matched non-frail controls (1.05+/-0.88 versus 0.53+/-0.39, p=0.04). CXCL-10 expression correlated with IL-6 levels only in frail participants (Spearman correlation coefficient r=0.52, p=0.03). Furthermore, frailty-associated CXCL-10 upregulation was highly correlated with IL-6 elevation, both measured by frail-over-non-frail ratios (r=0.93, p<0.0001). These findings suggest upregulated monocytic expression of CXCL-10 as an important molecular mechanism that contributes to inflammation activation in frail older adults. Therapeutic implications include potential development of CXCL-10-based interventional strategies for the prevention and treatment of frailty in older adults.