Elucidating the causal nexus and immune mediation between frailty and chronic kidney disease: integrative multi-omics analysis.

BACKGROUND: Empirical research has consistently documented the concurrent manifestation of frailty and chronic kidney disease (CKD). However, the existence of a reverse causal association or the influence of confounding variables on these correlations remains ambiguous. METHODS: Our analysis of 7,078 participants from National Health and Nutrition Examination Survey(NHANES) (1999-2018) applied weighted logistic regression and Mendelian Randomization (MR) to investigate the correlation between the frailty index (FI) and renal function. The multivariate MR analysis was specifically adjusted for type 2 diabetes and hypertension. Further analysis explored 3282 plasma proteins to link FI to CKD. A two-step network MR highlighted immune cells' mediating roles in the FI-CKD relationship. RESULT: Genetically inferred FI and various renal function markers are significantly correlated, as supported by NHANES analyses. Multivariate MR analysis revealed a direct causal association between the FI and CKD. Additionally, our investigation into plasma proteins identified Tmprss11D and MICB correlated with FI and CKD, respectively. A two-step network MR to reveal 15 immune cell types, notably Central Memory CD4+ T cells and Lymphocytes, as crucial mediators between FI and CKD. CONCLUSION: Our work establishes a causal connection between frailty and CKD, mediated by specific immune cell profiles. These findings highlight the importance of immune mechanisms in the frailty-CKD interplay and suggest that targeting shared risk factors and immune pathways could improve management strategies for these conditions. Our research contributes to a more nuanced understanding of frailty and CKD, offering new avenues for intervention and patient care in an aging population.

Circulating Angiogenic and Senescent T Lymphocytes in Ageing and Frailty.

BACKGROUND: There is a need to identify vascular and geroscience-relevant markers and mediators that can physiologically link ageing to vascular disease. There is evidence of specific T cell subsets, all influenced by age, that exert positive and negative effects on vascular health. CD31+, termed angiogenic T cells, have been linked to vascular repair whereas CD28null, termed senescent T cells, display pro-inflammatory and cytotoxic effector functions. OBJECTIVE: This study sought to determine the combined influence of increasing age and frailty status on these circulating CD31+ and CD28null T cell subsets. METHODS: This cross-sectional study recruited four different cohorts of men and women; young (20-30 years, n=22), older (65-75 years, n=17), robust non-frail (76+ years, n=17), and frail (76+ years, n=15) adults. Frailty was determined using the Fried Frailty method. T cell subsets were determined by whole blood flow cytometry based on the expression of CD3, CD4, CD8, CD31 and CD28. Cognitive impairment (CI) was measured via the Montreal Cognitive Assessment test. RESULTS: Whether expressed as circulating counts or as a % of total T cells, there was a progressive decrease (p<0.05) in CD31+ T cells with increasing age but paradoxically higher values (p<0.05) in the frail compared to the robust non-frail group. These changes were similar in the CD4+ and CD8+ fractions. CD28null T cells were considerably higher (p<0.05) in the frail compared to the robust non-frail group, including in the CD8+ (47% vs 29%, p<0.05) and CD4+ (4% vs 1%, p<0.05) fractions. CD28null T cell percentage was also higher (p<0.05) in those with moderate CI compared to mild CI and normal function. CONCLUSION: CD8+CD28null T cells are considerably elevated in frailty and with cognitive impairment and may serve as a useful target for intervention. Currently, the utility of CD31+ T cells as an ageing biomarker may be confined to healthy ageing cohorts.

Mitochondrial Oxidative Stress Regulates FOXP3+ T-Cell Activity and CD4-Mediated Inflammation in Older Adults with Frailty.

In healthy older adults, the immune system generally preserves its response and contributes to a long, healthy lifespan. However, rapid deterioration in immune regulation can lead to chronic inflammation, termed inflammaging, which accelerates pathological aging and diminishes the quality of life in older adults with frailty. A significant limitation in current aging research is the predominant focus on comparisons between young and older populations, often overlooking the differences between healthy older adults and those experiencing pathological aging. Our study elucidates the intricate immunological dynamics of the CD4/Treg axis in frail older adults compared to comparable age-matched healthy older adults. By utilizing publicly available RNA sequencing and single-cell RNA sequencing (scRNAseq) data from peripheral blood mononuclear cells (PBMCs), we identified a specific Treg cell subset and transcriptional landscape contributing to the dysregulation of CD4+ T-cell responses. We explored the molecular mechanisms underpinning Treg dysfunction, revealing that Tregs from frail older adults exhibit reduced mitochondrial protein levels, impairing mitochondrial oxidative phosphorylation. This impairment is driven by the TNF/NF-kappa B pathway, leading to cumulative inflammation. Further, we gained a deeper understanding of the CD4/Treg axis by predicting the effects of gene perturbations on cellular signaling networks. Collectively, these findings highlight the age-related relationship between mitochondrial dysfunction in the CD4/Treg axis and its role in accelerating aging and frailty in older adults. Targeting Treg dysfunction offers a critical basis for developing tailored therapeutic strategies aimed at improving the quality of life in older adults.

Links Between Inflammation, Mood, and Physical Function Among Older Adults With HIV.

OBJECTIVES: People living with human immunodeficiency virus (PLWH) treated with antiretrovirals have life spans similar to their HIV-negative peers. Yet, they experience elevated inflammation-related multimorbidity. Drawing on biopsychosocial determinants of health may inform interventions, but these links are understudied in older PLWH. We investigated cross-sectional relationships between psychosocial factors (mood, loneliness, and stigma), inflammatory markers, and age-related health outcomes among 143 PLWH aged 54-78 years. METHOD: Participants provided blood samples for serum cytokine and C-reactive protein (CRP) analyses, completed surveys assessing psychosocial factors and health, and completed frailty assessments. Regression models tested relationships between key psychosocial-, inflammation, and age-related health variables, adjusting for relevant sociodemographic and clinical factors. RESULTS: Participants with more depressive symptoms had higher composite cytokine levels than those with fewer depressive symptoms (ß = 0.22, t(126) = 2.71, p = .008). Those with higher cytokine levels were more likely to be prefrail or frail (adjusted odds ratio = 1.72, 95% confidence interval = 1.01-2.93) and reported worse physical function (ß = -0.23, t(129) = -2.64, p = .009) and more cognitive complaints (ß = -0.20, t(129) = -2.16, p = .03) than those with lower cytokine levels. CRP was not significantly related to these outcomes; 6-month fall history was not significantly related to inflammatory markers. DISCUSSION: Novel approaches are needed to manage comorbidities and maximize quality of life among older PLWH. Illustrating key expected biopsychosocial links, our findings highlight several factors (e.g., depressive symptoms, poorer physical function) that may share bidirectional relationships with chronic inflammation, a key factor driving morbidity. These links may be leveraged to modify factors that drive excessive health risk among older PLWH.

Impaired Functional T-Cell Response to SARS-CoV-2 After Two Doses of BNT162b2 mRNA Vaccine in Older People.

Long-term care facility (LTCF) older residents display physiological alterations of cellular and humoral immunity that affect vaccine responses. Preliminary reports suggested a low early postvaccination antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The aim of this study was to focus on the specific T-cell response. We quantified S1-specific IgG, neutralizing antibody titers, total specific IFNγ-secreting T cells by ELISpot, and functionality of CD4+- and CD8+-specific T cells by flow cytometry, after two doses of the BNT162b2 vaccine in younger and older people, with and without previous COVID-19 infection (hereafter referred to as COVID-19-recovered and COVID-19-naive subjects, respectively). Frailty, nutritional, and immunosenescence parameters were collected at baseline in COVID-19-naive older people. We analyzed the immune response in 129 young adults (median age 44.0 years) and 105 older residents living in a LCTF (median age 86.5 years), 3 months after the first injection. Humoral and cellular memory responses were dramatically impaired in the COVID-19-naive older (n = 54) compared with the COVID-19-naive younger adults (n = 121). Notably, older participants' neutralizing antibodies were 10 times lower than the younger's antibody titers (p < 0.0001) and LCTF residents also had an impaired functional T-cell response: the frequencies of IFNγ+ and IFNγ+IL-2+TNFα+ cells among specific CD4+ T cells, and the frequency of specific CD8+ T cells were lower in COVID-19-naive older participants than in COVID-19-naive young adults (p < 0.0001 and p = 0.0018, respectively). However, COVID-19-recovered older participants (n = 51) had greater antibody and T-cell responses, including IFNγ+ and IFNγ+IL-2+TNFα+-specific CD4+ T cells (p < 0.0001), as well as TNFα+-specific CD8+ T cells (p < 0.001), than COVID-19-naive older adults. We also observed that "inflammageing" and particularly high plasma levels of TNFα was associated to poor antibody response in the older participants. In conclusion, our results show that the COVID-19-naive older people had low counts and impaired specific CD4+ and CD8+ T cells, in addition to impaired antibody response, and that specific studies are warranted to assess the efficiency of SARS-CoV-2 mRNA-based vaccines, as in other immunocompromised subjects. Our study also shows that, despite their physiological alterations of immunity, vaccination is highly efficient in boosting the prior natural memory response in COVID-19-recovered older people.

The impact of physical frailty on the response to inactivated influenza vaccine in older adults.

Physical frailty's impact on hemagglutination inhibition antibody titers (HAI) and peripheral blood mononuclear cell (PBMC) transcriptional responses after influenza vaccination is unclear. Physical frailty was assessed using the 5-item Fried frailty phenotype in 168 community- and assisted-living adults ≥55 years of age during an observational study. Blood was drawn before, 3, 7, and 28 days post-vaccination with the 2017-2018 inactivated influenza vaccine. HAI response to the A/H1N1 strain was measured at Days 0 and 28 using seropositivity, seroconversion, log2 HAI titers, and fold-rise in log2 HAI titers. RNA sequencing of PBMCs from Days 0, 3 and 7 was measured in 28 participants and compared using pathway analyses. Frailty was not significantly associated with any HAI outcome in multivariable models. Compared with non-frail participants, frail participants expressed decreased cell proliferation, metabolism, antibody production, and interferon signaling genes. Conversely, frail participants showed elevated gene expression in IL-8 signaling, T-cell exhaustion, and oxidative stress pathways compared with non-frail participants. These results suggest that reduced effectiveness of influenza vaccine among older, frail individuals may be attributed to immunosenescence-related changes in PBMCs that are not reflected in antibody levels.

New Insights for BPIFB4 in Cardiovascular Therapy.

Aging is the most relevant risk factor for cardiovascular diseases which are the main cause of mortality in industrialized countries. In this context, there is a progressive loss of cardiovascular homeostasis that translates in illness and death. The study of long living individuals (LLIs), which show compression of morbidity toward the end of their life, is a valuable approach to find the key to delay aging and postpone associate cardiovascular events. A contribution to the age-related decline of cardiovascular system (CVS) comes from the immune system; indeed, it is dysfunctional during aging, a process described as immunosenescence and comprises the combination of several processes overpowering both innate and adaptative immune system. We have recently discovered a longevity-associated variant (LAV) in bactericidal/permeability-increasing fold-containing family B member 4 (BPIFB4), which is a secreted protein able to enhance endothelial function through endothelial nitric oxide synthase (eNOS) activation and capable to protect from hypertension, atherosclerosis, diabetic cardiopathy, frailty, and inflammaging. Here, we sum up the state of the art of the mechanisms involved in the main pathological processes related to CVD (atherosclerosis, aging, diabetic cardiopathy, and frailty) and shed light on the therapeutic effects of LAV-BPIFB4 in these contexts.

Frailty Is Associated With Neutrophil Dysfunction Which Is Correctable With Phosphoinositol-3-Kinase Inhibitors.

Neutrophil dysfunction has been described with age, appears exaggerated in infection, with altered phosphoinositol signaling a potential mechanism. However, functional aging is heterogeneous. Frailty is a negative health status and is more common in older adults. We hypothesized that neutrophil migration may be compromised in frailty, associated with the degree of frailty experienced by the older person. We compared measures of frailty, neutrophil function, and systemic inflammation in 40 young and 77 older community-dwelling adults in the United Kingdom. Systemic neutrophils exhibited an age-associated reduction in the accuracy of migration (chemotaxis) which was further blunted with frailty. The degree of migratory inaccuracy correlated with physical (adjusted hand grip strength) and cognitive (Stroop test) markers of frailty. Regression analysis demonstrated that age, Charlson comorbidity index, and frailty index were able to predict neutrophil chemotaxis. Reduced chemotaxis of neutrophils from frail adults could be reversed using selective PI3K inhibitors. Exposure of neutrophils from young adults to plasma from chronically inflamed frail older adults could not recapitulate the migratory deficit in vitro, and there were no relationships with systemic inflammation and neutrophil dysfunction. Frailty exaggerated the neutrophil deficits seen with advanced age but aspects of the frailty-associated deficit in neutrophil function are rescuable and thus potentially form a therapeutic target to improve outcomes from infection in older adults.

The emerging role of T follicular helper (TFH) cells in aging: Influence on the immune frailty.

The world population is undergoing a rapid expansion of older adults. Aging is associated with numerous changes that affect all organs and systems, including every component of the immune system. Immunosenescence is a multifaceted process characterized by poor response to vaccine and higher incidence of bacterial and viral infections, cancer, cardiovascular and autoimmune diseases. Immunosenescence has been associated with chronic low-grade inflammation referred to as inflammaging, whose underlying mechanisms remain incompletely elucidated, including age-related changes affecting components of the innate and adaptive immune system. T follicular helper (TFH) cells, present in lymphoid organs and in peripheral blood, are specialized in providing cognate help to B cells and are required for the production of immunoglobulins. Several subsets of TFH cells have been identified in humans and mice and modifications in TFH cell phenotype and function progressively occur with age. Dysfunctional TFH cells play a role in cancer, autoimmune and cardiovascular diseases, all conditions particularly prevalent in elderly subjects. A specialized population of Treg cells, named T follicular regulatory (TFR) cells, present in lymphoid organs and in peripheral blood, exerts opposing roles to TFH cells in regulating immunity. Indeed, changes in TFH/TFR cell ratio constitute a relevant feature of aging. Herein we discuss the cellular and molecular changes in both TFH cells and TFR cells that occur in aging and recent findings suggesting that TFH cells and/or their subsets could be involved in atherosclerosis, cancer, and autoimmunity.

Frailty, markers of immune activation and oxidative stress in HIV infected elderly.

People living with HIV-1 experience an accelerated aging due to the persistent and chronic activation of the immune system. This phenomenon conduces to immune exhaustion and precipitate immunosenescence. In general, frailty is defined as a syndrome of physiological degeneration in the elderly. Circulating naïve and memory T cells were studied by flow cytometry in non-frail and frail HIV-1-infected groups. Thymopoiesis, cell activation, senescence and cell proliferation were analyzed by CD31, HLA-DR/CD38, CD28/CD57 and Ki-67 expression, respectively. Plasma levels of sCD14 and MDA were measured by ELISA. Frail infected individuals showed a reduced number of memory T cells, both CD4+ and CD8+ populations. Activated CD3+CD4+HLA-DR+ T cells were lower in frail individuals, and directly correlated with CD3+CD8+HLA-DR+ and CD8M cells. Senescent CD8+CD28-CD57+ cells were reduced in frail HIV-1 infected individuals and inversely correlated with CD8RTE, CD8N and CD3+CD4+HLA-DR+. Higher plasma levels of sCD14 and MDA were found in HIV-1 infected frail individuals. Our data show association among frailty, markers of immune activation and oxidative stress. Understanding the immune mechanisms underlying frailty status in HIV-1 population is of high relevance not only for the prediction of continuing longevity but also for the identification of potential strategies for the elderly.

Inflammation, Frailty and Cardiovascular Disease.

Chronic inflammation, which is called "inflamm-aging" , is characterized by an increased level of inflammatory cytokines in response to physiological and environmental stressors, and causes the immune system to function consistently at a low level, even though it is not effective. Possible causes of inflammaging include genetic susceptibility, visceral obesity, changes in gut microbiota and permeability, chronic infections and cellular senescence. Inflammation has a role in the development of many age-related diseases, such as frailty. Low grade chronic inflammation can also increase the risk of atherosclerosis and insulin resistance which are the leading mechanisms in the development of cardiovascular diseases (CVD). As it is well known that the risk of CVD is higher in older people with frailty and the risk of frailty is higher in patients with CVD, there may be relationship between inflammation and the development of CVD and frailty. Therefore, this important issue will be discussed in this chapter.

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.

Frailty syndrome is associated with changes in peripheral inflammatory markers in prostate cancer patients undergoing androgen deprivation therapy.

OBJECTIVE: To evaluate the role of peripheral inflammation (leukocyte differential count, the proinflammatory cytokines IL-beta, TNF-α, IL-6, IL-8, and the inflammatory markers fibrinogen and C-reactive protein [CRP]) in frailty syndrome in patients with prostate cancer (CaP) undergoing antiandrogen therapy (ADT). METHODS: A total of 46 men between 51 and 92 years of age with CaP and receiving ADT were classified as frail, prefrail or robust according to the Fried scale. A geriatric assessment was performed, based on the Minimental State Examination for cognitive function, the Barthel index for basic activities of daily living, the Yesavage scale for geriatric depression, and the Athens insomnia scale. In addition, blood samples were collected to assess peripheral inflammation biomarkers including proinflammatory cytokines, fibrinogen, CRP and leukocyte differential count, as well as other biochemical and hematological parameters. RESULTS: A significant negative correlation between the severity of frailty syndrome and lymphocyte count was observed (P < 0.01). The concentration of IL-6 (P < 0.05), CRP (P < 0.05), and fibrinogen (P < 0.01) were significantly associated with frailty syndrome, but not of TNF-α, IL-beta, or IL-8. The severity of frailty syndrome was not dependent upon the clinical disease stage at diagnosis, the time elapsed since CaP diagnosis, the presence of metastases, or prostatectomy. CONCLUSIONS: Further research into the role of leukocyte subtypes and peripheral inflammation and the associated adverse outcomes in patients with CaP under ADT is warranted in order to tailor interventions aimed at reducing symptoms of frailty syndrome, such as loss of muscle strength and low physical activity.

Frailty is associated with elevated CRP trajectories and higher numbers of neutrophils and monocytes.

BACKGROUND: With aging, the human immune system undergoes several changes. The clinical relevance of these changes, however, is relatively unknown. We investigated immunological aspects of human aging in relation to frailty in the Doetinchem Cohort Study (DCS). METHODS: We calculated a frailty index score based on 36 health parameters for each individual in the DCS with data obtained in the period 2008-2016. The frailty index was used to define three health groups ('healthy', 'intermediate', and 'frail'), stratified by age and sex. In a subcohort (n = 289, 60-85 years, selected by balanced random sampling per frailty group), we collected blood samples between October 2016 and March 2017 to determine absolute numbers of leukocyte subsets. In addition, cytomegalovirus serostatus was assessed. C-reactive protein (CRP) levels were longitudinally assessed in four consecutive plasma samples per individual. These samples had been previously collected (1993-2013) as part of the DCS at regular time intervals and spanning a period of >15 years. RESULTS: We observed higher numbers of myeloid derived neutrophils and monocytes in the frail group compared to the healthy group in both men and women, and, retrospectively, consistently higher CRP concentrations over a period of >15 years. An increase in CRP concentration with age was found in women, but not in men. Frailty was not associated with cytomegalovirus serostatus or with changes in lymphoid derived T-, B-, or NK-cell numbers. CONCLUSION: Frail elderly, compared to their age- and sex-matched peers, endure a chronic and stable low-grade inflammation, which is associated with a myeloid cell lineage expansion. These findings could help to monitor clinically significant immunological decline in the elderly.

Multifactorial immunodeficiency in frail elderly patients: Contributing factors and management.

Immunodeficiency in the elderly is multifactorial. The analysis of etiological factors demonstrates the major role of immunosenescence and protein-energy malnutrition (PEM) with high prevalence deficiencies in micronutrients such as vitamin D, zinc, or vitamin E in people aged above 75 years. PEM contributes to the numerous consequences of frailty syndrome, and mainly to susceptibility to infections including fungal infections, which are usually observed in immunodeficient patients. Particular attention should thus be paid to these patients. However, these peculiarities of the immune system aging and the aging-related vulnerability can lead to diagnostic delays and treatment escalation, mainly with antibiotics, as well as to a loss of time resulting in a loss of opportunity for patients. Antibiotic escalation also leads to microbiological selection pressure in frail elderly people, which can be deleterious in the long-term in case of opportunistic infections. Guidelines are mainly based on the identification and management of frailty, especially in terms of nutrition. The identification of nutritional risk, dietary management, mood vigilance, and a functional approach are the four pillars of the management strategy. These elements are part of a global geriatric assessment and care.

Immunological alterations in frail older adults: A cross sectional study.

Frailty is a progressive physiologic decline in multiple body systems, characterized by loss of function, loss of physiologic reserve, and increased vulnerability to disease and death. This condition is induced by a complex and multifactorial interaction between genetic, biological, physical, psychological and environmental factors. To understand the interplay between the age-related decline of the immune response, and the upregulation of the inflammatory response, the so called inflammaging, we investigated the role of different inflammatory mediators on frailty status in the elderly. The study was performed in a population of 180 older adults (≥65 years), who were classified according to Fried's frailty phenotype. Plasma concentrations of neopterin, tryptophan, kynurenine, phenylalanine, tyrosine as well as kynurenine/tryptophan (Kyn/Trp) and phenylalanine/tyrosine (Phe/Tyr) ratios were analyzed as immune stimulation biomarkers. In addition, nitrite and C-reactive protein levels were measured as indicators of nitric oxide production and acute inflammation, respectively. Significant increases in neopterin, C-reactive protein and Kyn/Trp ratio, and decreases in tryptophan and nitrite concentrations in frail individuals compared with non-frail group were found. Both Kyn/Trp and Phe/Tyr ratios were significantly and positively correlated with neopterin. A positive correlation between kynurenine and tryptophan was also observed. Four parameters, i.e., neopterin, tryptophan, nitrite and C-reactive protein, were found to be strongly related to frailty status, although only nitrite confirmed its role of predictor after multiple regression analysis, supporting its use as a potential biomarker of frailty. Further investigation is required to strengthen the consistence and reproducibility of these findings, and to establish this parameter as a clinical biomarker of frailty.

The pulmonary rehabilitation regimen: a treatment for frailty and 'inflammaging'?

Pulmonary rehabilitation is an exercise-based intervention that improves walking endurance, strength, functional independence, wellbeing and the risk of re-admission to hospital. It was developed for patients recovering from acute exacerbations of chronic obstructive pulmonary disease, and sometimes other long-term inflammatory lung diseases. Many other conditions have a chronic inflammatory component, including type 2 diabetes, obesity, osteoarthritis and old age. Such background inflammation is linked to a range of adverse outcomes, including all-cause mortality, sarcopenia and other markers of frailty. Exercise, including pulmonary rehabilitation, has an anti-inflammatory effect on innate immune chemistry, and improves outcomes in a variety of conditions, although for most diagnostic groups there is no consistent structured programme similar to pulmonary rehabilitation. The authors contend that the pulmonary rehabilitation model could be used generically to treat other chronic and post-acute inflammatory states and thereby reduce the risk of frailty and other adverse outcomes.