Evaluation of T-cell aging-related immune phenotypes in the context of biological aging and multimorbidity in the Health and Retirement Study

Socioeconomic status is negatively associated with immunosenescence but positively associated with inflammation among middle-aged women in Cebu, Philippines

BACKGROUND

Socioeconomic status (SES) gradients in health are well-documented, and while biological pathways are incompletely understood, chronic inflammation and accelerated immune aging (immunosenescence) among lower SES individuals have been implicated. However, previous findings have come from samples in higher income countries, and it is unclear how generalizable they are to lower- and middle-income countries (LMIC) with different infectious exposures and where adiposity-an important contributor to chronic inflammation-might show different SES patterning. To address this gap, we explored associations between SES and inflammation and immunosenescence in a sample of women in Cebu, Philippines.

METHODS

Data came from the mothers of the Cebu Longitudinal Health and Nutrition Survey birth cohort (mean age: 47.7, range: 35-69 years). SES was measured as a combination of annual household income, education level, and assets. Chronic inflammation was measured using C-reactive protein (CRP) in plasma samples from 1,834 women. Immunosenescence was measured by the abundance of exhausted CD8T (CD8 + CD28-CD45RA-) and naïve CD8T and CD4T cells, estimated from DNA methylation in whole blood in a random subsample of 1,028. Possible mediators included waist circumference and a collection of proxy measures of pathogen exposure.

RESULTS

SES was negatively associated with the measures of immunosenescence, with slight evidence for mediation by a proxy measure for pathogen exposure from the household's drinking water source. In contrast, SES was positively associated with CRP, which was explained by the positive association with waist circumference.

CONCLUSIONS

Similar to higher income populations, in Cebu there is an SES-gradient in pathogen exposures and immunosenescence. However, lifestyle changes occurring more rapidly among higher SES individuals is contributing to a positive association between SES and adiposity and inflammation. Our results suggest more studies are needed to clarify the relationship between SES and inflammation and immunosenescence across LMIC.

Aging-Related Immune Cell Phenotypes and Mortality in the Framingham Heart Study

Background

The global increase in human life expectancy is evident. The total number of individuals aged 60 or above is anticipated to reach 2 billion by 2050. Aging, an inherently complex process, manifests prominently in the changes observed in the immune system. A notable marker of immune system aging is the presence of Aging-Related Immune Cell Phenotypes (ARIPs). Despite their significance, the connections between various ARIPs and mortality have not been thoroughly investigated. We prospectively investigated 16 different ARIPs using flow cytometry, namely, CD4/CD8 ratio, Granzyme B + CD8/Granyzme B + CD4, TN/TM = Tn / (Teff + Tem + Tcm) for TN/TM CD4 + and TN/TM CD8 + ratios, Th17/CD4 + Treg, Tc17/CD8 + Treg, Th17, Tc17, CD4 + Temra, CD8 + Temra, CD4 + CD25 + FoxP3+ (CD4 + Treg), CD8 + CD25 + FoxP3+ (CD8 + Treg) CD4 + CD27-, CD4 + CD28-CD27-, CD8 + CD27-, CD8 + CD28-CD27- and IL-6 in relation to survival outcome among dementia-free Framingham Heart Study (FHS) offspring cohort participants who attended the seventh exam (1998-2001).

Results

Among 996 participants (mean age 62 years, range 40 to 88 years, 52% female), the survival rate was 65% during 19 years of follow-up. For the model adjusting for age, sex, and cytomegalovirus (CMV) serostatus, higher CD4/CD8 and Tc17/CD8 + Treg ratios were significantly associated with lower all-cause mortality (HR:0.86 [0.76-0.96], 0.84 [0.74-0.94], respectively) and higher CD8 regulatory cell levels (CD8 + CD25 + FoxP3+) were associated with higher all-cause mortality (HR = 1.17, [1.03-1.32]). Higher IL-6 levels were associated with higher all-cause, cardiovascular, and non-cardiovascular mortality (HR = 1.43 [1.26-1.62], 1.70 [1.31-2.21], and 1.36 [1.18-1.57], respectively).

The Phenotypic Characterization of the Oldest Italian Man from December 28, 2020, to September 23, 2021, A.T., Strengthens the Idea That the Immune System can Play a Key Role in the Attainment of Extreme Longevity

In this paper, we present demographic, clinical, anamnestic, cognitive, and functional data, as well as haematological, haematochemical, immunological, and genetic parameters of an exceptional individual: A.T., a semi-supercentenarian who held the title of the oldest living Italian male centenarian from 28 December 2020, to 23 September 2021. The purpose of this study is to provide fresh insights into extreme phenotypes, with a particular focus on immune-inflammatory parameters. To the best of our knowledge, this study represents the first phenotypic investigation of a semi-supercentenarian, illustrating both INFLA-score, a metric designed to assess the cumulative impact of inflammatory markers and indicators of age-related immune phenotype (ARIP), recognized as significant gauges of biological ageing. The aim of this study was, indeed, to advance our understanding of the role of immune-inflammatory responses in achieving extreme longevity. The results of laboratory tests, as well as clinical history and interview data, when compared to the results of our recent study on Sicilian centenarians, demonstrate an excellent state of health considering his age. Consistent with previous studies, we observed increased IL-6 inflammatory markers and INFLA score in A.T. More interestingly, the semi-supercentenarian showed values of ARIP indicators such as naïve CD4+ cells, CD4+/CD8+ ratio, and CD4+TN/TM ratio in the range of young adult individuals, suggesting that his immune system's biological age was younger than the chronological one. The results support the notion that the immune system can play a role in promoting extreme longevity. However, this does not rule out the involvement of other body systems or organs in achieving extreme longevity.

Immune cells are associated with mortality: the Health and Retirement Study

Introduction

Age-related immunosenescence is characterized by changes in immune cell subsets and is associated with mortality. However, since immunosenescence is associated with other concurrent age-related changes such as inflammation and multi-organ dysfunction, it is unclear whether the association between age-related immunosenescence and mortality is independent of other concurrent age-related changes. To address these limitations, we evaluated the independent association between immune cell subsets and mortality after adjustment for age-related inflammation and biologic age.

Methods

Data for this study was obtained from the 2016 interview of the Health and Retirement Study (N=6802). Cox proportional hazards regression models were used to estimate the association between 25 immune cell subsets (11 T-cell subsets, 4 B-cell subsets, 3 monocyte subsets, 3 natural killer cell subsets, 3 dendritic cell subsets, and neutrophils) and 4-year mortality adjusting for covariates such as the Klemera-Doubal algorithm biological age, chronological age, gender, race/ethnicity, BMI, smoking status, comorbidity index, CMV seropositivity, and inflammatory latent variable comprising C-reactive protein, and 4 cytokines (interleukin-10, interleukin-1 receptor antagonist, interleukin-6, and soluble tumor necrosis factor).

Results

Four hundred and seventy-six participants died during the study period with an overall median follow up time of 2.5 years. After controlling for covariates and adjustment for sample-weights, total T cells [HR: 0.86, p=0.004], NK CD56LO cells [HR: 0.88, p=0.005], and neutrophils [HR: 1.22, p=0.004] were significantly associated with mortality.

Conclusions

These findings support the idea that an aging immune system is associated with short-term mortality independent of age-related inflammation or other age-related measures of physiological dysfunction. If replicated in other external cohorts, these findings could identify novel targets for both monitoring and intervention to reduce the age-related mortality.

Chronic Stress and Latent Virus Reactivation: Effects on Immune Aging, Chronic Disease Morbidity, and Mortality

OBJECTIVES

Social stress has been shown to affect immune functioning. Past research has found that chronic social stress and latent viral infections accelerate immune aging, leading to chronic disease morbidity and mortality. Chronic stress may also reactivate latent viral infections, like cytomegalovirus (CMV), accelerating the aging of the immune system.

METHOD

Utilizing panel survey data from 8,995 U.S. adults aged 56 or older from the Health and Retirement Study, this study investigates whether chronic stress interacts with CMV positivity to drive aging of the immune system, multimorbidity, and mortality.

RESULTS

Results of moderated mediation analysis indicate that the effect of CMV positivity on morbidity and mortality as mediated by immune aging indicators is amplified by chronic stress.

DISCUSSION

These findings suggest that immune aging is a biological pathway underlying the stress process and help explain past findings in the literature on stress and health.

COVID-19-Related Age Profiles for SARS-CoV-2 Variants in England and Wales and States of the USA (2020 to 2022): Impact on All-Cause Mortality

Since 2020, COVID-19 has caused serious mortality around the world. Given the ambiguity in establishing COVID-19 as the direct cause of death, we first investigate the effects of age and sex on all-cause mortality during 2020 and 2021 in England and Wales. Since infectious agents have their own unique age profile for death, we use a 9-year time series and several different methods to adjust single-year-of-age deaths in England and Wales during 2019 (the pre-COVID-19 base year) to a pathogen-neutral single-year-of-age baseline. This adjusted base year is then used to confirm the widely reported higher deaths in males for most ages above 43 in both 2020 and 2021. During 2020 (+COVID-19 but no vaccination), both male and female population-adjusted deaths significantly increased above age 35. A significant reduction in all-cause mortality among both males and females aged 75+ could be demonstrated in 2021 during the widespread COVID-19 vaccination period; however, deaths below age 75 progressively increased. This finding arises from a mix of vaccination coverage and year-of-age profiles of deaths for the different SARS-CoV-2 variants. In addition, specific effects of age around puberty were demonstrated, where females had higher deaths than males. There is evidence that year-of-birth cohorts may also be involved, indicating that immune priming to specific pathogen outbreaks in the past may have led to lower deaths for some birth cohorts. To specifically identify the age profile for the COVID-19 variants from 2020 to 2023, we employ the proportion of total deaths at each age that are potentially due to or 'with' COVID-19. The original Wuhan strain and the Alpha variant show somewhat limited divergence in the age profile, with the Alpha variant shifting to a moderately higher proportion of deaths below age 84. The Delta variant specifically targeted individuals below age 65. The Omicron variants showed a significantly lower proportion of overall mortality, with a markedly higher relative proportion of deaths above age 65, steeply increasing with age to a maximum around 100 years of age. A similar age profile for the variants can be seen in the age-banded deaths in US states, although they are slightly obscured by using age bands rather than single years of age. However, the US data shows that higher male deaths are greatly dependent on age and the COVID variant. Deaths assessed to be 'due to' COVID-19 (as opposed to 'involving' COVID-19) in England and Wales were especially overestimated in 2021 relative to the change in all-cause mortality. This arose as a by-product of an increase in COVID-19 testing capacity in late 2020. Potential structure-function mechanisms for the age-specificity of SARS-CoV-2 variants are discussed, along with potential roles for small noncoding RNAs (miRNAs). Using data from England, it is possible to show that the unvaccinated do indeed have a unique age profile for death from each variant and that vaccination alters the shape of the age profile in a manner dependent on age, sex, and the variant. The question is posed as to whether vaccines based on different variants carry a specific age profile.

From Immunosenescence to Aging Types-Establishing Reference Intervals for Immune Age Biomarkers by Centile Estimation

Immunological aging type definition requires establishing reference intervals from the distribution of immunosenescence biomarkers conditional on age. For 1605 individuals (18-97 years), we determined the comprehensive immune age index IMMAX from flow-cytometry-based blood cell sub-populations and identified age-specific centiles by fitting generalized additive models for location, scale, and shape. The centiles were uncorrelated with age and facilitated the categorization of individuals as immunologically slow or fast aging types. Using its 50th percentile as a reference, we rescaled the IMMAX to equivalent years of life (EYOL) and computed the immunological age gap as the difference between EYOL and chronological age. Applied to preliminary baseline and follow-up measurements from 53 participants of the Dortmund Vital Study (Clinical-Trials.gov Identifier: NCT05155397), the averaged changes in the IMMAX and EYOL conformed to the 5-year follow-up period, whereas no significant changes occurred concerning IMMAX centiles and age gap. This suggested that the participants immunologically adapted to aging and kept their relative positions within the cohort. Sex was non-significant. Methodical comparisons indicated that future confirmatory analyses with the completed follow-up examinations could rely on percentile curves estimated by simple linear quantile regression, while the selection of the immunosenescence biomarker will greatly influence the outcome, with IMMAX representing the preferable choice.

Cytomegalovirus and Epstein-Barr virus co-infected young and middle-aged adults can have an aging-related T-cell phenotype

Cytomegalovirus (CMV) is known to alter circulating effector memory or re-expressing CD45RA⁺ (TemRA) T-cell numbers, but whether Epstein-Barr virus (EBV) does the same or this is amplified during a CMV and EBV co-infection is unclear. Immune cell numbers in blood of children and young, middle-aged, and senior adults (n = 336) were determined with flow cytometry, and additional multivariate linear regression, intra-group correlation, and cluster analyses were performed. Compared to non-infected controls, CMV-seropositive individuals from all age groups had more immune cell variance, and CMV⁺ EBV^- senior adults had more late-differentiated CD4⁺ and CD8⁺ TemRA and CD4⁺ effector memory T-cells. EBV-seropositive children and young adults had a more equal immune cell composition than non-infected controls, and CMV^- EBV⁺ senior adults had more intermediate/late-differentiated CD4⁺ TemRA and effector memory T-cells than non-infected controls. CMV and EBV co-infected young and middle-aged adults with an elevated BMI and anti-CMV antibody levels had a similar immune cell composition as senior adults, and CMV⁺ EBV⁺ middle-aged adults had more late-differentiated CD8⁺ TemRA, effector memory, and HLA-DR⁺ CD38^- T-cells than CMV⁺ EBV^- controls. This study identified changes in T-cell numbers in CMV- or EBV-seropositive individuals and that some CMV and EBV co-infected young and middle-aged adults had an aging-related T-cell phenotype.

Circulating immune cell phenotypes are associated with age, sex, CMV, and smoking status in the Framingham Heart Study offspring participants

Understanding the composition of circulating immune cells with aging and the underlying biologic mechanisms driving aging may provide molecular targets to slow the aging process and reduce age-related disease. Utilizing cryopreserved cells from 996 Framingham Heart Study (FHS) Offspring Cohort participants aged 40 and older (mean 62 years, 48% female), we report on 116 immune cell phenotypes including monocytes, T-, B-, and NK cells and their subtypes, across age groups, sex, cytomegalovirus (CMV) exposure groups, smoking and other cardiovascular risk factors. The major cellular differences with CMV exposure were higher Granzyme B+ cells, effector cells, and effector-memory re-expressing CD45RA (TEMRA) cells for both CD4+ and CD8+. Older age was associated with lower CD3+ T cells, lower naïve cells and naïve/memory ratios for CD4+ and CD8+. We identified many immune cell differences by sex, with males showing lower naïve cells and higher effector and effector memory cells. Current smokers showed lower pro-inflammatory CD8 cells, higher CD8 regulatory type cells and altered B cell subsets. No significant associations were seen with BMI and other cardiovascular risk factors. Our cross-sectional observations of immune cell phenotypes provide a reference to further the understanding of the complexity of immune cells in blood, an easily accessible tissue.

Personality and aging-related immune phenotype

An aging-related immune phenotype (ARIP) has been defined as a decrease in naïve T cells (T_N) relative to the accumulation of memory T cells (T_M). Recent research implicates ARIP measures, such as CD4 +T_N/T_M and CD8 +T_N/T_M ratios, in multimorbidity and mortality. This study examined whether psychological dispositions that assess how people think, feel, and behave are related to CD4 +T_N/T_M and CD8 +T_N/T_M. Participants were adults aged 50-104 years (N = 4798; 58% women, Mean Age= 67.95, SD= 9.56) from the Health and Retirement Study. Data on CD4 +T_N/T_M and CD8 +T_N/T_M were obtained in 2016. Data on personality, demographic factors, and potential clinical (body mass index, disease burden), behavioral (smoking, alcohol, physical activity), psychological (depressive symptoms, stress), and biological (cytomegalovirus IgG antibodies) mediating factors were obtained in 2014/2016. Controlling for demographic factors, higher conscientiousness was related to higher CD4 +T_N/T_M and CD8 +T_N/T_M. To a lesser extent, higher neuroticism and lower extraversion were associated with lower CD4 +T_N/T_M. Physical activity, and to a lesser extent BMI and disease burden, were the most robust mediators between personality and ARIP measures. Cytomegalovirus IgG level mediated the association between conscientiousness and both CD4 +T_N/T_M and CD8 +T_N/T_M. This study provides novel evidence that personality is related to ARIP. Higher conscientiousness and, to a lesser extent, higher extraversion may be protective against age-related immunophenotype change, whereas neuroticism may be a risk factor.

What's the role of thymus in diabetes mellitus?

Diabetes mellitus is considered as an autoimmune inflammatory and age-related disease. As an important immune organ, the thymus is involved in the immune response and inflammatory response process. Therefore, there may be a link between changes in thymus function and diabetes. Based on previous studies, we hypothesized that thymus dysfunction due to aging and other reasons leads to changes in the generation of various inflammatory-immune cells and inflammatory cytokines that regulate insulin resistance, and then participates in the development of diabetes and its complications. Therefore, thymus may be a key factor in diabetes and complications, and it may be a promising therapeutic strategy to improve the thymus function for patients with diabetes. The purpose of this review is to summarize and discuss recent advances in the influence of thymus function on diabetes, especially its potential mechanisms.

Age-related changes in peripheral T-cell subpopulations in elderly individuals: An observational study

The age-related decline in T-cell function among elderly individuals remains unclear. We thus investigated the interrelationship between T-cell subsets and age to identify the changes in T-cell phenotypes and develop an age prediction model for the elderly population. A total of 127 individuals aged >60 years were divided into three groups (youngest-old group, 61-70 years, n = 34; middle-old group, 71-80 years, n = 53; and oldest-old group, ≥ 81 years, n = 40). The percentage of CD8+CD28- cells (P = 0.001) was highest in the oldest-old group and then followed by the middle-old group, while the youngest-old group was the lowest. Both females and males demonstrated significant decreases in the absolute counts of CD4+CD45RA+ cells (P = 0.020; P = 0.002) and CD8+CD28+ cells (P = 0.015; P = 0.005) with age. Multivariate linear regression showed that the percentage of CD8+CD28- cells (P < 0.001) was an independent predictor of aging after adjusting for sex, body mass index, hospitalization duration, smoking, drinking, chronic medical illness, and medications at admission. In conclusion, our results suggest that aging in elderly individuals is accompanied by a decrease in the counts of T-cell subpopulations. CD8+CD28- cells may be potential targets for elderly individuals in antiaging-related immunosenescence.

Links between inflammation and immune functioning with cognitive status among older Americans in the Health and Retirement Study

Elevated inflammation and poor immune functioning are tied to worse cognitive health. Both processes are fundamental to aging and are strongly implicated in the development of age-related health outcomes, including cognitive status. However, results from prior studies evaluating links between indicators of inflammation and immune function and cognitive impairment have been inconsistent due to biomarker selection, sample selection, and cognitive outcome. Using the Health and Retirement Study (HRS), a nationally representative study of older adults in the United States, we assessed how indicators of inflammation (neutrophil-lymphocyte ratio (NLR), albumin, CRP, IL6, IL10, IL-1Ra, sTNFR1, and TGFβ1) and immune functioning (CMV, CD4+ TN/TM, and CD8+ TN/TM) are associated with cognitive status. First, to examine the association between each biomarker and cognitive status, we tested whether markers of inflammation and immune functioning varied across cognitive status categories. We found that dementia and cognitive impairment without dementia (CIND) were associated with elevated inflammation and poorer immune functioning across biomarkers except for CD4+ TN/TM. Next, we estimated multinomial logistic regression models to assess which biomarkers would continue to be associated with dementia and CIND, net of each other. In these models, albumin, cytokines, CMV, CD4+ TN/TM, and CD8+ TN/TM are associated with cognitive status. Because poor immune functioning and increased inflammation are associated with cognitive impairment, improving immune functioning and reducing inflammation may provide a mechanism for reducing ADRD risk in the population.

Calibrating a Comprehensive Immune Age Metric to Analyze the Cross Sectional Age-Related Decline in Cardiorespiratory Fitness

Cardiorespiratory fitness (CRF) is essential for sustained work ability in good health, but declines with aging, as does the functionality of the immune system, the latter process commonly referred to as immunosenescence. This study aimed to compare the capacity of immunosenescence biomarkers with chronological age for predicting low CRF in a cross-sectional sample recruited from the regional working population. CRF was determined by submaximal bicycle ergometer testing in a cross-sectional sample of 597 volunteers aged 20-70 years from the 'Dortmund Vital Study' (DVS, ClinicalTrials.gov Identifier: NCT05155397). Low CRF was scored if the ergometer test was not completed due to medical reasons or if the power output projected to a heart rate of 130 bpm divided by body mass was below sex-specific reference values of 1.25 W/kg for females and 1.5 W/kg for males, respectively. In addition to established biomarkers of immunosenescence, we calibrated a comprehensive metric of immune age to our data and compared its predictive capacity for low CRF to chronological age, while adjusting our analysis for the influence of sex, obesity, and the level of regular physical activity, by applying univariate and multiple logistic regression. While obesity, low physical activity, chronological and immune age were all associated with increased probability for low CRF in univariate analyses, multiple logistic regression revealed that obesity and physical activity together with immune age, but not chronological age, were statistically significant predictors of low CRF outcome. Sex was non-significant due to the applied sex-specific reference values. These results demonstrate that biological age assessed by our immunological metric can outperform chronological age as a predictor for CRF and indicate a potential role for immunosenescence in explaining the inter-individual variability of the age-related decline in cardiorespiratory fitness.