Analysis of cytomegalovirus-specific T-cell responses in patients with hypertension: comparison of assay methods and antigens

Associations of circulating T-cell subsets with carotid artery stiffness: the multiethnic study of atherosclerosis

Arterial stiffness measured by total pulse wave velocity (T-PWV) is associated with an increased risk of multiple age-related diseases. T-PWV can be described by structural (S-PWV) and load-dependent (LD-PWV) arterial stiffening. T-cells have been implicated in arterial remodeling, arterial stiffness, and hypertension in humans and animals; however, it is unknown whether T-cells are risk factors for T-PWV or its components. Therefore, we evaluated the cross-sectional associations of peripheral T-cell subpopulations with T-PWV, S-PWV, and LD-PWV. Peripheral blood T-cells were characterized using flow cytometry, and carotid artery stiffness was measured using B-mode ultrasound to calculate T-PWV at the baseline examination in a participant subset of the Multi-Ethnic Study of Atherosclerosis (MESA, n = 1,984). A participant-specific exponential model was used to calculate S-PWV and LD-PWV based on elastic modulus and blood pressure gradients. The associations between five primary (P-significance < 0.01) and 25 exploratory (P-significance < 0.05) immune cell subpopulations, per 1-SD increment, and arterial stiffness measures were assessed using adjusted linear regression models. For the primary analysis, higher CD4+CD28-CD57+, but not CD8+CD28-CD57+, T-cells were associated with higher LD-PWV (β = 0.04 m/s, P < 0.01) after adjusting for covariates. None of the remaining T-cell subpopulations in the primary analysis were associated with T-PWV or S-PWV. For the exploratory analysis, several memory and differentiated/senescence-associated CD4+ and CD8+ T-cell subpopulations were associated with greater T-PWV, S-PWV, and LD-PWV after adjusting for covariates. In conclusion, we highlight novel associations in humans between CD4+ and CD8+ memory and differentiated/senescence-associated T-cell subpopulations and measures of arterial stiffness in MESA. These results warrant longitudinal, prospective studies that examine changes in T-cell subpopulations and arterial stiffness in humans.NEW & NOTEWORTHY We investigated associations between T-cells and novel measures of structural and load-dependent arterial stiffness in a large multiethnic cohort. The primary analysis revealed that pro-inflammatory, senescence-associated CD4+CD28-CD57+ T-cells were associated with higher load-dependent arterial stiffness. An exploratory analysis revealed that multiple pro-inflammatory CD4+ and CD8+ T-cell subpopulations were associated with both higher structural and load-dependent arterial stiffness. These results suggest that pro-inflammatory T-cells may contribute to arterial stiffness through both arterial remodeling and elevated blood pressure.

The role of T cells in vascular aging, hypertension, and atherosclerosis

Vascular dysfunction has emerged as a significant risk factor for the development of cardio- and cerebrovascular diseases (CVDs), which are currently the leading cause of morbidity and mortality worldwide. T lymphocytes (T cells) have been shown to be important modulators of vascular function in primary aging and CVDs, likely by producing inflammatory cytokines and reactive oxygen species that influence vasoprotective molecules. This review summarizes the role of T cells on vascular function in aging, hypertension, and atherosclerosis in animals and humans, and discusses potential T-cell targeted therapeutics to prevent, delay, or reverse vascular dysfunction.

T-Cell Senescence in Human Metabolic Diseases

Immunosenescence denotes a state of dysregulated immune cell function characterized by a confluence of factors, including arrested cell cycle, telomere shortening, markers of cellular stress, mitochondrial dysfunction, loss of proteostasis, epigenetic reprogramming, and secretion of proinflammatory mediators. This state primarily manifests during the aging process but can also be induced in various pathological conditions, encompassing chronic viral infections, autoimmune diseases, and metabolic disorders. Age-associated immune system alterations extend to innate and adaptive immune cells, with T-cells exhibiting heightened susceptibility to immunosenescence. In particular, senescent T-cells have been identified in the context of metabolic disorders such as obesity, diabetes, and cardiovascular diseases. Recent investigations suggest a direct link between T-cell senescence, inflammation, and insulin resistance. The perturbation of biological homeostasis by senescent T-cells appears intricately linked to the initiation and progression of metabolic diseases, particularly through inflammation-mediated insulin resistance. Consequently, senescent T-cells are emerging as a noteworthy therapeutic target. This review aims to elucidate the intricate relationship between metabolic diseases and T-cell senescence, providing insights into the potential roles of senescent T-cells in the pathogenesis of metabolic disorders. Through a comprehensive examination of current research findings, this review seeks to contribute to a deeper understanding of the complex interplay between immunosenescence and metabolic health.

Association of T-cell receptor repertoires and arterial stiffness in patients with essential hypertension

BACKGROUND

Abnormal immune responses, particularly T-cell activity, are linked to vascular complications in hypertension, but mechanisms remain unknown. Our study aims to explore the association between arterial stiffness, assessed by brachial-ankle pulse wave velocity (baPWV), and T-cell receptor (TCR) repertoires in essential hypertension patients, focusing on understanding the role of T cells in the development of arterial stiffness in this population.

METHODS

The study included 301 essential hypertension patients and 48 age-matched normotensive controls. Essential hypertension patients were stratified into high (baPWV ≥1400 cm/s, n = 213) and low (baPWV <1400 cm/s, n = 88) baPWV groups. High-throughput sequencing analyzed peripheral TCRβ repertoires.

RESULTS

Significant TCRβ repertoire differences were observed between essential hypertension and normotensive groups, as well as between high and low baPWV essential hypertension subgroups. Specifically, patients in the high baPWV group exhibited notable variations in the utilization of specific TCR beta joining (TRBJ) and variable (TRBV) genes compared to the low baPWV group. These alterations were accompanied by reduced TCRβ diversity (represented by diversity 50 s), increased percentages of the largest TCRβ clones, and a higher number of TCRβ clones exceeding 0.1%. The presence of specific TCRβ clones was detected in both groups. Furthermore, reduced diversity 50s and elevated percentages of the largest TCRβ clones were independently correlated with baPWV, emerging as potential risk factors for increased baPWV in essential hypertension patients.

CONCLUSION

TCR repertoires were independently associated with arterial stiffness in patients with essential hypertension, implicating a potential role for dysregulated T-cell responses in the pathogenesis of arterial stiffness in this patient population.Trial registration: ChiCTR2100054414.

Associations of circulating T-cell subsets in carotid artery stiffness: the Multi-Ethnic Study of Atherosclerosis

Background

Arterial stiffness measured by total pulse wave velocity (T-PWV) is associated with increased risk of multiple age-related diseases. T-PWV can be described by structural (S-PWV) and load-dependent (LD-PWV) arterial stiffening. T-cells have been associated with arterial remodeling, blood pressure, and arterial stiffness in humans and animals; however, it is unknown whether T-cells are related to S-PWV or LD-PWV. Therefore, we evaluated the cross-sectional associations of peripheral T-cell subpopulations with T-PWV, S-PWV, and LD-PWV stiffness.

Methods

Peripheral blood T-cells were characterized using flow cytometry and the carotid artery was measured using B-mode ultrasound to calculate T-PWV at the baseline examination in a subset of the Multi-Ethnic Study of Atherosclerosis (MESA, n=1,984). A participant-specific exponential model was used to calculate S-PWV and LD-PWV based on elastic modulus and blood pressure gradients. The associations between five primary (p-significance<0.01) and twenty-five exploratory (p-significance<0.05) immune cell subpopulations, per 1-SD increment, and arterial stiffness measures were assessed using adjusted, linear regressions.

Results

For the primary analysis, higher CD4+CD28-CD57+ T-cells were associated with higher LD-PWV (β=0.04 m/s, p<0.01) after adjusting for co-variates. For the exploratory analysis, T-cell subpopulations that commonly shift with aging towards memory and differentiated/immunosenescent phenotypes were associated with greater T-PWV, S-PWV, and LD-PWV after adjusting for co-variates.

Conclusions

In this cross-sectional study, several T-cell subpopulations commonly associated with aging were related with measures of arterial stiffness. Longitudinal studies that examine changes in T-cell subpopulations and measures of arterial stiffness are warranted.

CD8+ T-cell metabolism is related to cerebrovascular reactivity in middle-aged adults

Cerebrovascular reactivity (CVR) decreases with advancing age, contributing to increased risk of cognitive impairment; however, the mechanisms underlying the age-related decrease in CVR are incompletely understood. Age-related changes to T cells, such as impaired mitochondrial respiration, increased inflammation, likely contribute to peripheral and cerebrovascular dysfunction in animals. However, whether T-cell mitochondrial respiration is related to cerebrovascular function in humans is not known. Therefore, we hypothesized that peripheral T-cell mitochondrial respiration would be positively associated with CVR and that T-cell glycolytic metabolism would be negatively associated with CVR. Twenty middle-aged adults (58 ± 5 yr) were recruited for this study. T cells were separated from peripheral blood mononuclear cells. Cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR, a marker of glycolytic activity) were measured using extracellular flux analysis. CVR was quantified using the breath-hold index (BHI), which reflects the change in blood velocity in the middle-cerebral artery (MCAv) during a 30-s breath-hold. In contrast to our hypothesis, we found that basal OCR in CD8+ T cells (β = -0.59, R2 = 0.27, P = 0.019) was negatively associated with BHI. However, in accordance with our hypothesis, we found that basal ECAR (β = -2.20, R2 = 0.29, P = 0.015) and maximum ECAR (β = -50, R2 = 0.24, P = 0.029) were negatively associated with BHI in CD8+ T cells. There were no associations observed in CD4+ T cells. These associations appeared to be primarily mediated by an association with the pressor response to the breath-hold test. Overall, our findings suggest that CD8+ T-cell respiration and glycolytic activity may influence CVR in humans.NEW & NOTEWORTHY Peripheral T-cell metabolism is related to in vivo cerebrovascular reactivity in humans. Higher glycolytic metabolism in CD8+ T cells was associated with lower cerebrovascular reactivity to a breath-hold in middle-aged adults, which is possibly reflective of a more proinflammatory state in midlife.

Proficiency tests to evaluate the impact on assay outcomes of harmonized influenza-specific Intracellular Cytokine Staining (ICS) and IFN-ɣ Enzyme-Linked ImmunoSpot (ELISpot) protocols

The magnitude and quality of cell-mediated immune responses elicited by natural infection or vaccination are commonly measured by Interferon-ɣ (IFN-ɣ) Enzyme-Linked ImmunoSpot (ELISpot) and Intracellular Cytokine Staining (ICS). To date, laboratories apply a variety of in-house procedures which leads to diverging results, complicates interlaboratory comparisons and hampers vaccine evaluations. During the FLUCOP project, efforts have been made to develop harmonized Standard Operating Procedures (SOPs) for influenza-specific IFN-ɣ ELISpot and ICS assays. Exploratory pilot studies provided information about the interlaboratory variation before harmonization efforts were initiated. Here we report the results of two proficiency tests organized to evaluate the impact of the harmonization effort on assay results and the performance of participating FLUCOP partners. The introduction of the IFN-ɣ ELISpot SOP reduced variation of both background and stimulated responses. Post-harmonization background responses were all lower than an arbitrary threshold of 50 SFU/million cells. When stimulated with A/California and B/Phuket, a statistically significant reduction in variation (p < 0.0001) was observed and CV values were strongly reduced, from 148% to 77% for A/California and from 126% to 73% for B/Phuket. The harmonizing effect of applying an ICS SOP was also confirmed by an increased homogeneity of data obtained by the individual labs. The application of acceptance criteria on cell viability and background responses further enhanced the data homogeneity. Finally, as the same set of samples was analyzed by both the IFN-ɣ ELISpot and the ICS assays, a method comparison was performed. A clear correlation between the two methods was observed, but they cannot be considered interchangeable. In conclusion, proficiency tests show that a limited harmonization effort consisting of the introduction of SOPs and the use of the same in vitro stimulating antigens leads to a reduction of the interlaboratory variation of IFN-ɣ ELISpot data and demonstrate that substantial improvements for the ICS assay are achieved as comparable laboratory datasets could be generated. Additional steps to further reduce the interlaboratory variation of ICS data can consist of standardized gating templates and detailed data reporting instructions as well as further efforts to harmonize reagent and instrument use.

Human Cytomegalovirus Infection and Cardiovascular Disease: Current Perspectives

Infections with human cytomegalovirus (HCMV) are often asymptomatic in healthy adults but can be severe in people with a compromised immune system. While several studies have demonstrated associations between cardiovascular disease in older adults and HCMV seropositivity, the underlying mechanisms are unclear. We review evidence published within the last 5 years establishing how HCMV can contribute directly and indirectly to the development and progression of atherosclerotic plaques. We also discuss associations between HCMV infection and cardiovascular outcomes in populations with a high or very high burden of HCMV, including patients with renal or autoimmune disease, transplant recipients, and people living with HIV.

Cytomegalovirus-specific CD8+ T-cell responses are associated with arterial blood pressure in people living with HIV

People living with HIV (PLHIV) are at increased risk for cardiovascular disease (CVD), and immunity against cytomegalovirus (CMV) may be a contributing factor. We hypothesized that enhanced T-cell responses against CMV and CMV-IgG antibody-levels are associated with higher arterial blood pressure in PLHIV. We assessed serum CMV-IgG, systolic- (SBP) and diastolic- (DBP) blood pressure, pulse pressure (PP), traditional risk factors, activated CD8+ T-cells (CD38+HLA-DR+), senescent CD8+ T-cells (CD28-CD57+) and interleukin-6 (IL-6) in 60 PLHIV and 31 HIV-uninfected controls matched on age, gender, education and comorbidity. In PLHIV, expression of interleukin-2, tumor necrosis factor-α and interferon-γ was measured by intracellular-cytokine-staining after stimulation of T-cells with CMV-pp65 and CMV-gB. Associations between CMV-specific immune responses and hypertension, SBP, DBP or PP were assessed by multivariate logistic and linear regression models adjusted for appropriate confounders. The median age of PLHIV was 47 years and 90% were male. Prevalence of hypertension in PLHIV was 37% compared to 55% of HIV-uninfected controls. CMV-specific CD8+ T-cell responses were independently associated with higher PP (CMV-pp65; β = 2.29, p = 0.001, CMV-gB; β = 2.42, p = 0.001) in PLHIV. No significant differences were found with regard to individual measures of SBP and DBP. A possible weak association was found between CMV-IgG and hypertension (β = 1.33, p = 0.049) after adjustment for age, smoking and LDL-cholesterol. HIV-related factors, IL-6, CD8+ T-cell activation or CD8+ T-cell senescence did not mediate the associations, and no associations were found between CMV-specific CD4+ T-cell responses and blood pressure in PLHIV. In conclusion, increased arterial blood pressure in PLHIV may be affected by heightened CMV-specific CD8+ T-cell responses.

Prevalence of Epstein-Barr virus, human papillomavirus, cytomegalovirus and herpes simplex virus type 1 in patients with diabetes mellitus type 2 in south-eastern Poland

A microbiota is a complex ecosystem of microorganisms consisting of bacteria, viruses, protozoa, and fungi living in different niches of the human body, which plays an essential role in many metabolic functions. Modifications in the microbiota composition can lead to several diseases, including metabolic disorders. The aim of this study was to analyze the prevalence of four viruses which can cause persistent infections-Epstein-Barr virus (EBV), human papillomavirus (HPV), cytomegalovirus (CMV), and herpes simplex virus type 1 (HSV-1) in patients with diabetes mellitus type 2 (DM2). Blood, saliva and oral swabs were collected from all the study participants. The nested-PCR technique was used to detect the viral DNA. DNA of at least one virus was detected in 71.1% of diabetic patients and in 30% of individuals without diabetes. In patients with diabetes EBV DNA was detected the most frequently (25.4%), followed by HPV- 19.1%, HSV- 10.4% and CMV- 5.2%. A higher percentage of EBV+HPV co-infection was found among men (30.8%). EBV DNA was statistically more often detected in patients living in rural areas (53.7%), while HPV (91.5%) and EBV+HPV co-infection (22.2%) prevailed among patients from urban areas. In patients with a DM2 history longer than 10 years viral infection was detected more frequently. The prevalence of EBV, HPV and the EBV+HPV co-infection was significantly higher in diabetic patients than in individuals without diabetes. The frequency of these infections depended on the duration of the disease (DM2).

Increased frequency of CD4+CD57+ senescent T cells in patients with newly diagnosed acute heart failure: exploring new pathogenic mechanisms with clinical relevance

Recent animal studies showed T cells have a direct pathogenic role in the development of heart failure (HF). However, which subsets of T cells contribute to human HF pathogenesis and progression remains unclear. We characterized immunologic properties of various subsets of T cells and their clinical implications in human HF. Thirty-eight consecutive patients with newly diagnosed acute HF (21 males, mean age 66 ± 16 years) and 38 healthy control subjects (21 males, mean age 62 ± 12 years) were enrolled. We found that pro-inflammatory mediators, including CRP, IL-6 and IP-10 and the frequencies of CD57⁺ T cells in the CD4⁺ T cell population were significantly elevated in patients with acute HF compared to control subjects. A functional analysis of T cells from patients with acute HF revealed that the CD4⁺CD57⁺ T cell population exhibited a higher frequency of IFN-γ- and TNF-α- producing cells compared to the CD4⁺CD57⁻ T cell population. Furthermore, the frequency of CD4⁺CD57⁺ T cells at baseline and its elevation at the six-month follow-up were significantly related with the development of cardiovascular (CV) events, which were defined as CV mortality, cardiac transplantation, or rehospitalization due to HF exacerbation. In conclusion, CD4⁺CD57⁺ senescent T cells showed more inflammatory features and polyfunctionality and were associated with clinical outcome in patients with acute HF. More detailed study for senescent T cells might offer new opportunities for the prevention and treatment of human HF.