Biomarkers of human immunosenescence: impact of Cytomegalovirus infection

Cytomegalovirus durably primes neutrophil oxidative burst

Cytomegalovirus (CMV) is a ubiquitous herpes virus that infects most humans, thereafter persisting lifelong in tissues of the host. It is a known pathogen in immunosuppressed patients, but its impact on immunocompetent hosts remains less understood. Recent data have shown that CMV leaves a significant and long-lasting imprint in host immunity that may confer some protection against subsequent bacterial infection. Such innate immune activation may come at a cost, however, with potential to cause immunopathology. Neutrophils are central to many models of immunopathology, and while acute CMV infection is known to influence neutrophil biology, the impact of chronic CMV infection on neutrophil function remains unreported. Using our murine model of CMV infection and latency, we show that chronic CMV causes persistent enhancement of neutrophil oxidative burst well after resolution of acute infection. Moreover, this in vivo priming of marrow neutrophils is associated with enhanced formyl peptide receptor expression, and ultimately constitutive c-Jun N-terminal kinase phosphorylation and enhanced CD14 expression in/on circulating neutrophils. Finally, we show that neutrophil priming is dependent on viral load, suggesting that naturally infected human hosts will show variability in CMV-related neutrophil priming. Altogether, these findings represent a previously unrecognized and potentially important impact of chronic CMV infection on neutrophil responsiveness in immunocompetent hosts.

Interferon-gamma FlowSpot assay for the measurement of the T-cell response to cytomegalovirus

Objectives

We describe a new method, FlowSpot, to assess CMV-specific T-cell response by quantification of interferon-gamma (IFN-γ). CMV-specific, T-cell-released IFN-γ was captured by flow beads and measured via flow cytometry. In the present study, we used FlowSpot to assess CMV-specific T-cell response in healthy individuals. The FlowSpot results were compared with those of serological analysis and enzyme-linked immunospot (ELISpot) assay.

Methods

Experimental results and parameter analysis were investigated by using serological, ELISpot, and FlowSpot assays.

Results

The levels of IFN-γ, which is released from CMV-specific T-cells, were measured, and the results and parameter analysis showed a good correlation between FlowSpot and ELISpot. However, FlowSpot was more sensitive and better reflected the strength of IFN-γ secretion than did ELISpot.

Conclusions

Compared to ELISpot, FlowSpot has a high sensitivity and is cost and time effective. Thus, this method can be used in wider clinical and scientific applications.

T cell aging as a risk factor for autoimmunity

Immune aging is a complex process rendering the host susceptible to cancer, infection, and insufficient tissue repair. Many autoimmune diseases preferentially occur during the second half of life, counterintuitive to the concept of excess adaptive immunity driving immune-mediated tissue damage. T cells are particularly susceptible to aging-imposed changes, as they are under extreme proliferative pressure to fulfill the demands of clonal expansion and of homeostatic T cell repopulation. T cells in older adults have a footprint of genetic and epigenetic changes, lack mitochondrial fitness, and fail to maintain proteostasis, diverging them from host protection to host injury. Here, we review recent progress in understanding how the human T-cell system ages and the evidence detailing how T cell aging contributes to autoimmune conditions. T cell aging is now recognized as a risk determinant in two prototypic autoimmune syndromes; rheumatoid arthritis and giant cell arteritis. The emerging concept adds susceptibility to autoimmune and autoinflammatory disease to the spectrum of aging-imposed adaptations and opens new opportunities for immunomodulatory therapy by restoring the functional intactness of aging T cells.

The influence of physical activity level and cytomegalovirus serostatus on the cytokine levels of young individuals

The practice of physical activity (PA) is a non-pharmacological variable that alters the immune response through changes in cytokines and cellular immunity. Inversely latent cytomegalovirus (CMV) infection prematurely ages the immune system and contributes to the chronic inflammatory condition in several diseases and in aging. This study aimed to compare the association of the PA level and CMV serostatus on whole blood mitogen-stimulated cytokine production of young individuals. The resting blood samples were collected from 100 volunteers of both sexes assigned to one of six groups according to the degree of PA and CMV serostatus: sedentary CMV- (n = 15), moderate physical activity CMV- (moderate PA CMV -, n = 15), high physical activity CMV- (high PA CMV-, n = 15), sedentary CMV+ (n = 20), moderate physical activity CMV + (moderate PA CMV+, n = 20) and high physical activity CMV + (high PA CMV +, n = 20). The collected peripheral blood got diluted in supplemented RPMI-1640 culture medium and incubated for 48 hours with a 2% concentration of phytohemagglutinin at 37ºC and CO2 at 5%. The supernatants were collected and used for the IL-6, IL-10, TNF-α, and INF-γ analysis by the ELISA method. The IL-10 concentration was higher in the Moderate PA and High PA groups when compared to the sedentary group, regardless of CMV status. The physically active (moderate and high PA) CMV+ individuals presented lower concentrations of IL-6 and TNF-α compared to CMV+ sedentary individuals, and the sedentary CMV+ subjects had a higher concentration of INF-γ compared to Sedentary CMV- subjects (p < 0.05). In summary, it is possible to infer that PA is key to controlling inflammation related to CMV infection. The stimulation of physical exercise is an important factor in controlling many diseases at the populational level.

Prospective Evaluation of CD45RA+/CCR7- Effector Memory T (TEMRA) Cell Subsets in Patients with Primary and Secondary Brain Tumors during Radiotherapy of the Brain within the Scope of the Prospective Glio-CMV-01 Clinical Trial

Radiotherapy (RT) of the brain is a common treatment for patients with high-grade gliomas and brain metastases. It has previously been shown that reactivation of cytomegalovirus (CMV) frequently occurs during RT of the brain. This causes neurological decline, demands antiviral treatment, and is associated with a worse prognosis. CMV-specific T cells are characterized by a differentiated effector memory phenotype and CD45RA+ CCR7- effector memory T (T_EMRA) cells were shown to be enriched in CMV seropositive individuals. In this study, we investigated the distribution of T_EMRA cells and their subsets in the peripheral blood of healthy donors and, for the first time, prospectively within the scope of the prospective Glio-CMV-01 clinical trial of patients with high-grade glioma and brain metastases during radiation therapy as a potential predictive marker. First, we developed a multicolor flow cytometry-based assay to monitor the frequency and distribution of T_EMRA cells in a longitudinal manner. The CMV serostatus and age were considered as influencing factors. We revealed that patients who had a reactivation of CMV have significantly higher amounts of CD8+ T_EMRA cells. Further, the distribution of the subsets of T_EMRA cells based on the expression of CD27, CD28, and CD57 is highly dependent on the CMV serostatus. We conclude that the percentage of CD8+ T_EMRA cells out of all CD8+ T cells has the potential to serve as a biomarker for predicting the risk of CMV reactivation during RT of the brain. Furthermore, this study highlights the importance of taking the CMV serostatus into account when analyzing T_EMRA cells and their subsets.

The role of late-differentiated T cells, a proxy for IFN-γ-production, in older adults' social networks

Interferon-γ (IFN-γ), an inflammatory biomarker that promotes antiviral immunity, may be a prerequisite for sociability. IFN-γ production in older adulthood is driven by late-differentiated CD8+ T cells, particularly CD28-and CD57+ subsets, which increase with age, reduce immune response, and increase chronic disease risk. The present study investigated the relationship between late-differentiated T cells (LDTC) and sociability in a longitudinal study of healthy aging. 139 older adults (Mage = 77.95, range 65-93; 58% female, 57% college educated, and 94% Caucasian) provided data at up to 10 occasions (M = 7). Social network size and diversity and cytomegalovirus (CMV) status were collected at every wave. Percentage of LDTC was measured at up to 4 waves and averaged for each participant. There were no significant main effects of LDTC or interactions between LDTC and time on social network size or diversity. Adjustment for baseline age, gender, and sensitivity analyses including CMV and imputed data did not change results. IFN-γ may not play a role in dictating social behavior in older adults. Alternately, LDTC may not have accurately represented circulating levels of IFN-γ. Future work should continue exploring IFN-γ and social behavior, particularly as it relates to age-related changes. The role of IFN-γ-producing, late-differentiated T cells in older adults' social networks.

How Can We Improve the Vaccination Response in Older People? Part II: Targeting Immunosenescence of Adaptive Immunity Cells

The number of people that are 65 years old or older has been increasing due to the improvement in medicine and public health. However, this trend is not accompanied by an increase in quality of life, and this population is vulnerable to most illnesses, especially to infectious diseases. Vaccination is the best strategy to prevent this fact, but older people present a less efficient response, as their immune system is weaker due mainly to a phenomenon known as immunosenescence. The adaptive immune system is constituted by two types of lymphocytes, T and B cells, and the function and fitness of these cell populations are affected during ageing. Here, we review the impact of ageing on T and B cells and discuss the approaches that have been described or proposed to modulate and reverse the decline of the ageing adaptive immune system.

Contemporary nutrition-based interventions to reduce risk of infection among elderly long-term care residents: A scoping review

Background

Elderly long-term care residents (ELTCRs) face considerable burden of infection, especially evident during the COVID-19 pandemic. The nutritional status of the host can influence susceptibility to infection by altering immune system integrity, therefore, nutrition-based interventions may be a viable complement to existing infection prevention measures.

Objective

This scoping review sought to identify nutritional interventions and factors that have the strongest evidence to benefit ELTCRs, and thus best poised for rigorous clinical trial evaluation and subsequent implementation.

Methods

A database search of OVID-Medline, OVID-Embase, and Web of Science was performed from 2011 to 2021 to identify nutritional intervention studies which attribute to changes in infection in contemporary ELTCR settings. Articles were screened in duplicate and data extraction completed by a single reviewer, while a second reviewer verified the data which was fitted to identify evidence for nutritional interventions related to reducing rates of infection among ELTCRs.

Results

The search identified 1018 studies, of which 11 (nine clinical trials and two observational cohort studies) satisfied screening criteria. Interventions that significantly reduced risk of infection included whey protein (any infection), Black Chokeberry (urinary tract infection), and vitamin D (acute respiratory tract infection, skin and soft tissue infection). Both zinc and a dedicated meal-plan significantly improved lymphocyte parameters. Vitamin D deficiency was associated with the development of respiratory tract infections. Probiotic and soy-based protein interventions did not significantly affect risk of infection or lymphocyte parameters, respectively.

Conclusion

The current scoping review was effective in identifying the use of nutrition-based interventions for infection prevention among ELTCRs. In this study, some nutrition-based interventions were observed to significantly influence the risk of infection among ELTCRs. Nutritional interventions such as vitamin D (preventing deficiency/insufficiency), Black Chokeberry juice, zinc gluconate, whey protein, and varied and nutrient dense meal plans may be suitable for future rigorous clinical trial evaluation.

T and B Cell Composition and Cytokine Producing Capacity Before and After Bariatric Surgery

Morbid obesity is associated with a chronic state of low-grade inflammation, which may lead to accelerated differentiation of T and B cells. These differentiated immune cells are strongly cytotoxic and have an increased pro-inflammatory cytokine producing capacity. Furthermore, the anti-inflammatory function of the T and B cells decreases. The aim of this study was to evaluate the effect of morbid obesity on the subset profile and cytokine producing capacity of T and B cells. Subsequently, we assessed whether bariatric surgery affected the subset profile and cytokine producing capacity of these cells. We determined the proportion of T and B cell subsets and their cytokine producing capacity in peripheral blood collected from 23 morbidly obese patients before and three months after bariatric surgery using flow-cytometry. We compared this with the results of 25 lean controls. Both CD4+ and CD8+ T cells showed a more differentiated subset profile in morbidly obese patients as compared to lean controls, which was not recovered three months after bariatric surgery. The B cell composition of morbidly obese patients after bariatric surgery adjusted towards the profile of lean controls. However, the IL-2 and IFN-γ producing capacity of CD8+ T cells and the IL-2, IFN-γ, TNF-α and IL-10 producing capacity of B cells was not restored three months after bariatric surgery. In conclusion, the data suggest that the immune system has the capacity to recover from the detrimental effects of morbid obesity within three months after bariatric surgery in terms of cell composition; however, this was not seen in terms of cytokine producing capacity. The full restoration of the immune system after bariatric surgery may thus take longer.

Clinical perspectives on the age-related increase of immunosuppressive activity

The aging process is associated with a remodeling of the immune system involving chronic low-grade inflammation and a gradual decline in the function of the immune system. These processes are also called inflammaging and immunosenescence. The age-related immune remodeling is associated with many clinical changes, e.g., risk for cancers and chronic infections increases, whereas the efficiency of vaccination and immunotherapy declines with aging. On the other hand, there is convincing evidence that chronic inflammatory states promote the premature aging process. The inflammation associated with aging or chronic inflammatory conditions stimulates a counteracting immunosuppression which protects tissues from excessive inflammatory injuries but promotes immunosenescence. Immunosuppression is a driving force in tumors and chronic infections and it also induces the tolerance to vaccination and immunotherapies. Immunosuppressive cells, e.g., myeloid-derived suppressor cells (MDSC), regulatory T cells (Treg), and type M2 macrophages, have a crucial role in tumorigenesis and chronic infections as well as in the tolerance to vaccination and immunotherapies. Interestingly, there is substantial evidence that inflammaging is also associated with an increased immunosuppressive activity, e.g., upregulation of immunosuppressive cells and anti-inflammatory cytokines. Given that both the aging and chronic inflammatory states involve the activation of immunosuppression and immunosenescence, this might explain why aging is a risk factor for tumorigenesis and chronic inflammatory states and conversely, chronic inflammatory insults promote the premature aging process in humans.

Cytomegalovirus Infection Associated with Smaller Total Cortical Surface Area in Schizophrenia Spectrum Disorders

OBJECTIVES

Cytomegalovirus (CMV) congenital infection and in immunodeficiency can have deleterious effects on human cortex. In immunocompetent adults, the putative association between CMV infection and cortical measures has not been explored. We hypothesized that CMV exposure is associated with smaller cortical surface area or cortical thinning mainly in patients with schizophrenia spectrum disorders.

STUDY DESIGN

We included 67 adult patients with schizophrenia spectrum disorders and 262 adult healthy controls. We measured circulating CMV IgG antibody concentrations with solid-phase immunoassay techniques. We measured the total cortical surface area, regional cortical surface areas and the overall mean cortical thickness based on T1-weighted MRI scans processed in FreeSurfer v6.0.

STUDY RESULTS

In the whole sample analysis, we found a significant diagnostic group-by-CMV status interaction on the total surface area (P = .020). Among patients, CMV antibody positivity was significantly associated with smaller total surface area (P = .002, partial eta2 = 0.138) whereas no such association was found in healthy controls (P = .059). Post hoc analysis among patients showed that higher CMV antibody concentrations were also significantly associated with smaller total surface area (P = .038), and that CMV antibody positivity was significantly inversely associated with 14 left and 16 right regional surface areas mainly in the frontal and temporal lobes. CMV infection was not associated with the overall mean cortical thickness.

CONCLUSIONS

The results are indicative of a cortical surface area vulnerability to CMV infection in patients with schizophrenia spectrum disorders but not in healthy controls. CMV infection may contribute to the established cortical surface area aberrations in schizophrenia.

Turnover of Murine Cytomegalovirus-Expanded CD8+ T Cells Is Similar to That of Memory Phenotype T Cells and Independent of the Magnitude of the Response

The potential of memory T cells to provide protection against reinfection is beyond question. Yet, it remains debated whether long-term T cell memory is due to long-lived memory cells. There is ample evidence that blood-derived memory phenotype CD8⁺ T cells maintain themselves through cell division, rather than through longevity of individual cells. It has recently been proposed, however, that there may be heterogeneity in the lifespans of memory T cells, depending on factors such as exposure to cognate Ag. CMV infection induces not only conventional, contracting T cell responses, but also inflationary CD8⁺ T cell responses, which are maintained at unusually high numbers, and are even thought to continue to expand over time. It has been proposed that such inflating T cell responses result from the accumulation of relatively long-lived CMV-specific memory CD8⁺ T cells. Using in vivo deuterium labeling and mathematical modeling, we found that the average production rates and expected lifespans of mouse CMV-specific CD8⁺ T cells are very similar to those of bulk memory-phenotype CD8⁺ T cells. Even CMV-specific inflationary CD8⁺ T cell responses that differ 3-fold in size were found to turn over at similar rates.

Vitamin D and the Immune System in Menopause: A Review

Menopause is a normal phenomenon in a woman’s life cycle involving multiple health-related issues that contribute to physical instability. Changes in the immune system in postmenopausal women are caused by estrogen deprivation along with age. Increased proinflammatory serum marker levels, cytokine responses in body cells, decreased CD4 T and B lymphocyte levels, and natural killer cell cytotoxic activity are also observed during postmenopause. Moreover, vitamin D, in addition to its classical effects on calcium homeostasis and bone density, plays an important role. Current evidence indicates that vitamin D regulates innate and adaptive immune responses; however, vitamin D deficiency is linked to increased autoimmune activity and infection susceptibility. This review provides an overview of the consequences of immune alterations as an outcome of aging in postmenopausal women and the benefit of vitamin D supplementation.

CMV exposure drives long-term CD57+ CD4 memory T-cell inflation following allogeneic stem cell transplant

Donor and recipient cytomegalovirus (CMV) serostatus correlate with transplant-related mortality that is associated with reduced survival following allogeneic stem cell transplant (SCT). Prior epidemiologic studies have suggested that CMV seronegative recipients (R-) receiving a CMV-seropositive graft (D+) experience inferior outcomes compared with other serostatus combinations, an observation that appears independent of viral reactivation. We therefore investigated the hypothesis that prior donor CMV exposure irreversibly modifies immunologic function after SCT. We identified a CD4+/CD57+/CD27- T-cell subset that was differentially expressed between D+ and D- transplants and validated results with 120 patient samples. This T-cell subset represents an average of 2.9% (D-/R-), 18% (D-/R+), 12% (D+/R-), and 19.6% (D+/R+) (P < .0001) of the total CD4+ T-cell compartment and stably persists for at least several years post-SCT. Even in the absence of CMV reactivation post-SCT, D+/R- transplants displayed a significant enrichment of these cells compared with D-/R- transplants (P = .0078). These are effector memory cells (CCR7-/CD45RA+/-) that express T-bet, Eomesodermin, granzyme B, secrete Th1 cytokines, and are enriched in CMV-specific T cells. These cells are associated with decreased T-cell receptor diversity (P < .0001) and reduced proportions of major histocompatibility class (MHC) II expressing classical monocytes (P < .0001), myeloid (P = .024), and plasmacytoid dendritic cells (P = .0014). These data describe a highly expanded CD4+ T-cell population and putative mechanisms by which prior donor or recipient CMV exposure may create a lasting immunologic imprint following SCT, providing a rationale for using D- grafts for R- transplant recipients.

Pathophysiology of Circulating Biomarkers and Relationship With Vascular Aging: A Review of the Literature From VascAgeNet Group on Circulating Biomarkers, European Cooperation in Science and Technology Action 18216

Impairment of the arteries is a product of sustained exposure to various deleterious factors and progresses with time; a phenomenon inherent to vascular aging. Oxidative stress, inflammation, the accumulation of harmful agents in high cardiovascular risk conditions, changes to the extracellular matrix, and/or alterations of the epigenetic modification of molecules, are all vital pathophysiological processes proven to contribute to vascular aging, and also lead to changes in levels of associated circulating molecules. Many of these molecules are consequently recognized as markers of vascular impairment and accelerated vascular aging in clinical and research settings, however, for these molecules to be classified as biomarkers of vascular aging, further criteria must be met. In this paper, we conducted a scoping literature review identifying thirty of the most important, and eight less important, biomarkers of vascular aging. Herein, we overview a selection of the most important molecules connected with the above-mentioned pathological conditions and study their usefulness as circulating biomarkers of vascular aging.

Quantification of T-cell dynamics during latent cytomegalovirus infection in humans

Cytomegalovirus (CMV) infection has a major impact on the T-cell pool, which is thought to be associated with ageing of the immune system. The effect on the T-cell pool has been interpreted as an effect of CMV on non-CMV specific T-cells. However, it remains unclear whether the effect of CMV could simply be explained by the presence of large, immunodominant, CMV-specific memory CD8+ T-cell populations. These have been suggested to establish through gradual accumulation of long-lived cells. However, little is known about their maintenance. We investigated the effect of CMV infection on T-cell dynamics in healthy older adults, and aimed to unravel the mechanisms of maintenance of large numbers of CMV-specific CD8+ T-cells. We studied the expression of senescence, proliferation, and apoptosis markers and quantified the in vivo dynamics of CMV-specific and other memory T-cell populations using in vivo deuterium labelling. Increased expression of late-stage differentiation markers by CD8+ T-cells of CMV+ versus CMV- individuals was not solely explained by the presence of large, immunodominant CMV-specific CD8+ T-cell populations. The lifespans of circulating CMV-specific CD8+ T-cells did not differ significantly from those of bulk memory CD8+ T-cells, and the lifespans of bulk memory CD8+ T-cells did not differ significantly between CMV- and CMV+ individuals. Memory CD4+ T-cells of CMV+ individuals showed increased expression of late-stage differentiation markers and decreased Ki-67 expression. Overall, the expression of senescence markers on T-cell populations correlated positively with their expected in vivo lifespan. Together, this work suggests that i) large, immunodominant CMV-specific CD8+ T-cell populations do not explain the phenotypical differences between CMV+ and CMV- individuals, ii) CMV infection hardly affects the dynamics of the T-cell pool, and iii) large numbers of CMV-specific CD8+ T-cells are not due to longer lifespans of these cells.

Antimicrobial stewardship in the ICU in COVID times: the known unknowns

Since the start of the COVID-19 pandemic, there has been concern about the concomitant rise of antimicrobial resistance. While bacterial co-infections seem rare in COVID-19 patients admitted to hospital wards and intensive care units (ICUs), an increase in empirical antibiotic use has been described. In the ICU setting, where antibiotics are already abundantly—and often inappropriately—prescribed, the need for an ICU-specific antimicrobial stewardship programme is widely advocated. Apart from essentially warning against the use of antibacterial drugs for the treatment of a viral infection, other aspects of ICU antimicrobial stewardship need to be considered in view of the clinical course and characteristics of COVID-19. First, the distinction between infectious and non-infectious (inflammatory) causes of respiratory deterioration during an ICU stay is difficult, and the much-debated relevance of fungal and viral co-infections adds to the complexity of empirical antimicrobial prescribing. Biomarkers such as procalcitonin for the decision to start antibacterial therapy for ICU nosocomial infections seem to be more promising in COVID-19 than non-COVID-19 patients. In COVID-19 patients, cytomegalovirus reactivation is an important factor to consider when assessing patients infected with SARS-CoV-2 as it may have a role in modulating the patient immune response. The diagnosis of COVID-19-associated invasive aspergillosis is challenging because of the lack of sensitivity and specificity of the available tests. Furthermore, altered pharmacokinetic/pharmacodynamic properties need to be taken into account when prescribing antimicrobial therapy. Future research should now further explore the ‘known unknowns’, ideally with robust prospective study designs.

Cytomegalovirus infection and IQ in patients with severe mental illness and healthy individuals

Cytomegalovirus (CMV) infection in immunocompetent adults is usually asymptomatic, but results in lifelong latency. Infection occurring congenitally or in immunodeficiency can lead to cognitive impairment. We aimed to investigate the associations between CMV exposure and intelligence quotient (IQ) in patients with schizophrenia spectrum disorders (SZS), bipolar spectrum disorders (BDS) and healthy controls (HC). CMV immunoglobulin G antibody concentrations were measured by immunoassay and expressed as dichotomous measures (seropositive/CMV+ vs. seronegative/CMV-). Based on a significant CMV-by-diagnosis-by-sex interaction on IQ, we investigated main and interaction effects of CMV and sex on IQ in each diagnostic category. Significant CMV-by-sex interactions were found in patient groups. In SZS, CMV+ female patients (n = 50) had significantly lower IQ than CMV- female patients (n = 33), whereas CMV+ (n = 48) and CMV- (n = 45) male patients did not differ in IQ. In BDS, CMV+ (n = 49) and CMV- (n = 37) female patients did not differ in IQ, whereas CMV+ male patients (n = 33) had significantly higher IQ than CMV- male patients (n = 32). Among HC, CMV+ (n = 138) and CMV- (n = 118) male participants as well as CMV+ (n = 125) and CMV- (n = 93) female participants did not differ in IQ. Our findings suggest that CMV exposure may affect IQ in patients with severe mental illness but not HC.

Impact of CMV and age on T cell subsets defined by CD161, CD300a, and/or CD57 expression in healthy Andalusians

Immunosenescence affects innate and adaptive immunity impairing the response to pathogens and vaccines. Chronic infection with cytomegalovirus (CMV) has been shown to drive 'early immunosenescence' and can considerably impact both the function and phenotype of immune cells, especially T cells. We have previously shown that the expression of CD57, CD300a, and CD161 was differentially affected by age and chronic CMV infection, indicating that these markers are a hallmark of CMV infection and T cell ageing. The aim of this present study was to clarify whether these three markers define distinct T cell subpopulations with a specific functional and molecular signature. Specifically, we analyzed the effect of age and chronic CMV infection on the functionality of T cells according to CD161, CD300a, and CD57 expression. We found that these markers defined different T cell subsets, both at the phenotypic and functional levels. CD57 was the best biomarker for CD4+ T cell cytotoxicity and was a hallmark of CMV infection. CD300a+ T cells were heterogeneous and included different cell subsets. The population of CD161+ T cells dramatically decreased with age, independently of CMV infection, and represented a sign of age-associated immune system alterations. The latter could contribute to an increased risk of autoimmune disease and infection in older adults. Our results underline the importance of better understanding the factors involved in the immunosenescence process to be able to uncover new biomarkers and open new avenues for the investigation and development of novel age-related disease therapies.

Hallmarks of T cell aging

The aged adaptive immune system is characterized by progressive dysfunction as well as increased autoimmunity. This decline is responsible for elevated susceptibility to infection and cancer, as well as decreased vaccination efficacy. Recent evidence indicates that CD4⁺ T cell-intrinsic alteratins contribute to chronic inflammation and are sufficient to accelerate an organism-wide aging phenotype, supporting the idea that T cell aging plays a major role in body-wide deterioration. In this Review, we propose ten molecular hallmarks to represent common denominators of T cell aging. These hallmarks are grouped into four primary hallmarks (thymic involution, mitochondrial dysfunction, genetic and epigenetic alterations, and loss of proteostasis) and four secondary hallmarks (reduction of the TCR repertoire, naive-memory imbalance, T cell senescence, and lack of effector plasticity), and together they explain the manifestation of the two integrative hallmarks (immunodeficiency and inflammaging). A major challenge now is weighing the relative impact of these hallmarks on T cell aging and understanding their interconnections, with the final goal of defining molecular targets for interventions in the aging process.

Latent CMV Infection Is Associated With Lower Influenza Virus-Specific Memory T-Cell Frequencies, but Not With an Impaired T-Cell Response to Acute Influenza Virus Infection

Latent infection with cytomegalovirus (CMV) is assumed to contribute to the age-associated decline of the immune system. CMV induces large changes in the T-cell pool and may thereby affect other immune responses. CMV is expected to impact especially older adults, who are already at higher risk of severe disease and hospitalization upon infections such as influenza virus (IAV) infection. Here, we investigated the impact of CMV infection on IAV-specific CD8⁺ T-cell frequencies in healthy individuals (n=96) and the response to IAV infection in older adults (n=72). IAV-specific memory T-cell frequencies were lower in healthy CMV⁺ older individuals compared to healthy CMV^- older individuals. Upon acute IAV infection, CMV serostatus or CMV-specific antibody levels were not negatively associated with IAV-specific T-cell frequencies, function, phenotype or T-cell receptor repertoire diversity. This suggests that specific T-cell responses upon acute IAV infection are not negatively affected by CMV. In addition, we found neither an association between CMV infection and inflammatory cytokine levels in serum during acute IAV infection nor between cytokine levels and the height of the IAV-specific T-cell response upon infection. Finally, CMV infection was not associated with increased severity of influenza-related symptoms. In fact, CMV infection was even associated with increased IAV-specific T-cell responses early upon acute IAV infection. In conclusion, although associated with lower frequencies of memory IAV-specific T cells in healthy individuals, CMV infection does not seem to hamper the induction of a proper T-cell response during acute IAV infection in older adults.

Age and CMV-Infection Jointly Affect the EBV-Specific CD8+ T-Cell Repertoire

CD8+ T cells play an important role in protection against viral infections. With age, changes in the T-cell pool occur, leading to diminished responses against both new and recurring infections in older adults. This is thought to be due to a decrease in both T-cell numbers and T-cell receptor (TCR) diversity. Latent infection with cytomegalovirus (CMV) is assumed to contribute to this age-associated decline of the immune system. The observation that the level of TCR diversity in the total memory T-cell pool stays relatively stable during aging is remarkable in light of the constant input of new antigen-specific memory T cells. What happens with the diversity of the individual antigen-specific T-cell repertoires in the memory pool remains largely unknown. Here we studied the effect of aging on the phenotype and repertoire diversity of CMV-specific and Epstein-Barr virus (EBV)-specific CD8+ T cells, as well as the separate effects of aging and CMV-infection on the EBV-specific T-cell repertoire. Antigen-specific T cells against both persistent viruses showed an age-related increase in the expression of markers associated with a more differentiated phenotype, including KLRG-1, an increase in the fraction of terminally differentiated T cells, and a decrease in the diversity of the T-cell repertoire. Not only age, but also CMV infection was associated with a decreased diversity of the EBV-specific T-cell repertoire. This suggests that both CMV infection and age can impact the T-cell repertoire against other antigens.

Age-dependency of terminal ileum tissue resident memory T cell responsiveness profiles to S. Typhi following oral Ty21a immunization in humans

BACKGROUND

The impact of aging on the immune system is unequivocal and results in an altered immune status termed immunosenescence. In humans, the mechanisms of immunosenescence have been examined almost exclusively in blood. However, most immune cells are present in tissue compartments and exhibit differential cell (e.g., memory T cells -TM) subset distributions. Thus, it is crucial to understand immunosenescence in tissues, especially those that are exposed to pathogens (e.g., intestine). Using a human model of oral live attenuated typhoid vaccine, Ty21a, we investigated the effect of aging on terminal ileum (TI) tissue resident memory T (TRM) cells. TRM provide immediate adaptive effector immune responsiveness at the infection site. However, it is unknown whether aging impacts TRM S. Typhi-responsive cells at the site of infection (e.g., TI). Here, we determined the effect of aging on the induction of TI S. Typhi-responsive TRM subsets elicited by Ty21a immunization.

RESULTS

We observed that aging impacts the frequencies of TI-lamina propria mononuclear cells (LPMC) TM and TRM in both Ty21a-vaccinated and control groups. In unvaccinated volunteers, the frequencies of LPMC CD103- CD4+ TRM displayed a positive correlation with age whilst the CD4/CD8 ratio in LPMC displayed a negative correlation with age. We observed that elderly volunteers have weaker S. Typhi-specific mucosal immune responses following Ty21a immunization compared to adults. For example, CD103+ CD4+ TRM showed reduced IL-17A production, while CD103- CD4+ TRM exhibited lower levels of IL-17A and IL-2 in the elderly than in adults following Ty21a immunization. Similar results were observed in LPMC CD8+ TRM and CD103- CD8+ T cell subsets. A comparison of multifunctional (MF) profiles of both CD4+ and CD8+ TRM subsets between elderly and adults also showed significant differences in the quality and quantity of elicited single (S) and MF responses.

CONCLUSIONS

Aging influences tissue resident TM S. Typhi-specific responses in the terminal ileum following oral Ty21a-immunization. This study is the first to provide insights in the generation of local vaccine-specific responses in the elderly population and highlights the importance of evaluating tissue immune responses in the context of infection and aging.

TRIAL REGISTRATION

This study was approved by the Institutional Review Board and registered on ClinicalTrials.gov (identifier NCT03970304 , Registered 29 May 2019 - Retrospectively registered).

Cytomegalovirus and herpes simplex type 1 infections and immunological profile of community-dwelling older adults

Chronic infections, such as cytomegalovirus (CMV) and herpes simplex virus type 1 (HSV-1), contribute to the inflammation process among older adults and are associated with the immunosenescence process. The aim was to identify the immunological profile associated with CMV and HSV-1 infections among older adults. This is a cross-sectional study, carried out with 1492 participants from the Bambuí Cohort Study of Aging - Minas Gerais, Brazil. For analysis purposes, we considered the presence of immunoglobulin G (IgG) for CMV and HSV-1 in the participants' serum, assessed by the enzyme-linked immunosorbent assay (ELISA); outcomes were defined by titration above the median (>160 UR/mL for HSV-1 and >399.5 U/mL for CMV). In order to assess the immunological profile, the following biomarkers were considered: IL-1beta, IL-10, IL-12, TNF, CXCL8, CXCL9, CXCL10, CCL2, CCL5, IL-6 and CRP; the first four being categorized as detectable levels or not, and the others using the Classification and Regression Tree (CART) method. The analysis was adjusted for sociodemographic variables, health behaviors and health conditions. The seroprevalence of anti CMV and anti HSV-1 antibodies was 99.4% and 97.0%, respectively. Higher concentrations of CXCL8 and CCL5 chemokines were associated with lower antibody titers for CMV, and higher concentrations of CXCL9, IL-6 and CRP were associated with higher levels of antibodies to CMV. Moreover, intermediate levels of CXCL10 were also associated with higher levels of antibodies to CMV. In HSV-1 infection, intermediate levels of CXCL9, CCL5 and IL-6 were less likely to have higher antibody titers for this infection. On the other hand, higher levels of CXCL10 and CRP were positively associated with higher antibody titers for HSV-1. The results describe important immunological changes and reinforce the potential effect of CMV and HSV-1 on the immunosenescence process.

Presence of Senescent and Memory CD8+ Leukocytes as Immunocenescence Markers in Skin Lesions of Elderly Leprosy Patients

Leprosy is an infectious disease that remains endemic in approximately 100 developing countries, where about 200,000 new cases are diagnosed each year. Moreover, multibacillary leprosy, the most contagious form of the disease, has been detected at continuously higher rates among Brazilian elderly people. Due to the so-called immunosenescence, characterized by several alterations in the quality of the immune response during aging, this group is more susceptible to infectious diseases. In view of such data, the purpose of our work was to investigate if age-related alterations in the immune response could influence the pathogenesis of leprosy. As such, we studied 87 individuals, 62 newly diagnosed and untreated leprosy patients distributed according to the age range and to the clinical forms of the disease and 25 healthy volunteers, who were studied as controls. The frequency of senescent and memory CD8⁺ leukocytes was assessed by immunofluorescence of biopsies from cutaneous lesions, while the serum levels of IgG anti-CMV antibodies were analyzed by chemiluminescence and the gene expression of T cell receptors' inhibitors by RT-qPCR. We noted an accumulation of memory CD8⁺ T lymphocytes, as well as reduced CD8⁺CD28⁺ cell expression in skin lesions from elderly patients, when compared to younger people. Alterations in LAG3 and PDCD1 gene expression in cutaneous lesions of young MB patients were also observed, when compared to elderly patients. Such data suggest that the age-related alterations of T lymphocyte subsets can facilitate the onset of leprosy in elderly patients, not to mention other chronic inflammatory diseases.

Pathogen Burden, Blood Biomarkers and Functional Ageing in Community-Dwelling Older Adults

BACKGROUND

Lifelong accumulation of latent or persistent or repeated infections may be a contributing factor to the deterioration of physical and cognitive function associated with functional ageing, but the evidence is limited and the biological underpinnings are unclear.

METHODS

We profiled the seropositivity for common viral, bacterial and plasmodial pathogens of local importance in community-living older adults in two studies involving 745 older adults (mean age 67.0, SD: 7.7 years), and 142 older adults (mean age 72.7, SD: 8.3 years). Pathogen load was related to different sets of age-related physical and cognitive measures of functional ageing and the frailty index, and plasma levels of biomarkers of inflammation, innate and adaptive immunity, and other physiological functions.

RESULTS

High pathogen load was associated with impaired gait speed (GS), (p<0.015), functional mobility (POMA) (p<0.029), cognitive function (MMSE) (p<<0.05), and increased frailty index (FI) (p<<0.05). High pathogen load was significantly associated with C3a complement activity (p<0.001), matrix metalloproteinase-7, macrophage inflammatory protein-1α (p<0.05), and monocyte chemoattractant protein 2 (p=0.028). Blood biomarkers did not fully explain the observed association between pathogen load and functional ageing measures.

CONCLUSIONS

The present study provides novel evidence linking lifelong cumulated numbers of latent, persistent or repeated infection to functional ageing, plausibly via inflammatory and immune and other biological factors.

Transcriptomics analysis for the identification of potential age-related genes and cells associated with three major urogenital cancers

Age is one of the most important risk factors of the occurrence for tumor patients. The majority of patients with urogenital cancers are the elderly, whose clinical characteristics are greatly affected by age and ageing. Our study aimed to explore age-related genes, cells, and biological changes in three common urogenital cancers via integrative bioinformatics analysis. First, mRNA (count format) and clinical data for bladder cancer, prostate cancer and renal cell carcinoma were downloaded from the Cancer Genome Atlas (TCGA). Through the comparison of clinicopathological characteristics, genes expression and cells infiltration between the old group and the young group, it was found that the clinical characteristics, genes and cells in the tumor microenvironment of different ages were quite different. And 4 key cells, 14 hub genes and some potential pathways were identified and considered as important factors. More importantly, we analyzed the differential landscape of the genes and cells from different perspectives, and confirmed its importance. In conclusion, we identified genes and cell types associated with age-related changes in the tumour microenvironment in urogenital cancer patients. These genes and cell types may play a critical role in the age-associated differences in clinicopathological characteristics among urogenital cancers, thus providing a link between ageing and cancer occurrence. The findings of this study may pave the way for the development of age-tailored approaches to treat cancer and other age-related diseases.

How age and infection history shape the antigen-specific CD8+ T-cell repertoire: Implications for vaccination strategies in older adults

Older adults often show signs of impaired CD8⁺ T‐cell immunity, reflected by weaker responses against new infections and vaccinations, and decreased protection against reinfection. This immune impairment is in part thought to be the consequence of a decrease in both T‐cell numbers and repertoire diversity. If this is indeed the case, a strategy to prevent infectious diseases in older adults could be the induction of protective memory responses through vaccination at a younger age. However, this requires that the induced immune responses are maintained until old age. It is therefore important to obtain insights into the long‐term maintenance of the antigen‐specific T‐cell repertoire. Here, we review the literature on the maintenance of antigen‐experienced CD8⁺ T‐cell repertoires against acute and chronic infections. We describe the complex interactions that play a role in shaping the memory T‐cell repertoire, and the effects of age, infection history, and T‐cell avidity. We discuss the implications of these findings for the development of new vaccination strategies to protect older adults.

Uraemia-induced immune senescence and clinical outcomes in chronic kidney disease patients

BACKGROUND

Patients with chronic kidney disease (CKD) are more prone to develop premature age-related diseases. Data on immune senescence are scarce in CKD populations, except in end-stage renal disease and dialysis. We designed a longitudinal prospective study to evaluate immune senescence at different CKD stages and its influence on CKD patient outcomes.

METHODS

Clinical and biological data collections were performed on 222 patients at different CKD stages [1-2 (n = 85), 4 (n = 53) and 5 (n = 84)]. Immune senescence biomarkers were measured by cytometry on T cells (CD28, CD57, CD45RA, CD31, γH2A.X) or by quantitative polymerase chain reaction [relative telomere length (RTL)] on peripheral blood mononuclear cells and analysed according to CKD stages and outcomes.

RESULTS

CKD was associated with an increase in immune senescence and inflammation biomarkers, as follows: low thymic output (197 ± 25 versus 88 ± 13 versus 73 ± 21 CD4+CD45RA+CD31+ T cells/mm3), an increased proportion of terminally differentiated T cells (CD8+CD28-CD57+) (24 ± 18 versus 32 ± 17 versus 35 ± 19%) restricted to cytomegalovirus-positive patients, telomere shortening (1.11 ± 0.36 versus 0.78 ± 0.24 versus 0.97 ± 0.21 telomere:single copy ratio) and an increase in C-reactive protein levels [median 2.9 (range 1.8-4.9) versus 5.1 (27-9.6) versus 6.2 (3.4-10.5) mg/L]. In multivariate analysis, shorter RTL was associated with death {hazard ratio [HR] 4.12 [95% confidence interval (CI) 1.44-11.75]}. Low thymic output was associated with infections [HR 1.79 (95% CI (1.34-9.58)] and terminally differentiated CD8+ T-cell expansion with a risk of cardiovascular events [CEs; HR 4.86 (95% CI 1.72-13.72)].

CONCLUSION

CKD was associated with premature immune ageing. Each of these alterations increased the risk of specific age-related diseases, such as RTL and death, thymic function and infections and terminally differentiated CD8+ T-cell expansion and CEs.

Exploratory study on immune phenotypes in Alzheimer's disease and vascular dementia

BACKGROUND AND PURPOSE

The differentiation of Alzheimer's disease (AD) dementia from vascular dementia (VaD) and mixed-type dementia (mixed dementia) requires stepwise analysis and usually occurs late in the disease process. Early diagnosis and therapy monitoring would benefit greatly from the identification of biomarkers of neurodegeneration, especially blood biomarkers. To this end, the aim of the present pilot study was to investigate differences in the distribution of peripheral T-cell populations in patients with AD compared to VaD and mixed dementia.

METHODS

Flow cytometry was performed on blood samples from 11 patients with AD, six with VaD and six with mixed dementia, as well as 17 healthy control subjects (HCs). CD4+ and CD8+ T cells were typed for expression of CD45, CD27, CD28, CD25, FoxP3, CCR4 and CCR6; the other leukocytes were also assessed. Functionally, immune cell uptake of the β-amyloid (Aβ) toxic fragment (Aβ_1-42 ) was also evaluated.

RESULTS

A higher proportion of CD4+CD28- memory T cells and a reciprocal reduction of CD4+CD28+CD27+ naïve T lymphocytes was detected in all patient groups relative to controls. Significantly fewer CD4+CD25+FoxP3 regulatory T cells were present in patients with VaD, and significantly more CCR6+ and CCR4+ CD4+ T cells in those with AD. Higher CCR6+ T-cell frequencies were also present in patients with mixed dementia, potentially due to the inflammation and immune cell chemoattraction triggered by Aβ.

CONCLUSIONS

The present study was a comprehensive investigation comparing different kinds of dementia, revealing differentially expressed peripheral markers that are potentially useful for early AD, VaD and mixed dementia diagnoses, and that would assist in proper treatments for these disparate diseases. Validation is now required.

Targeting Infectious Agents as a Therapeutic Strategy in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent dementia in the world. Its cause(s) are presently largely unknown. The most common explanation for AD, now, is the amyloid cascade hypothesis, which states that the cause of AD is senile plaque formation by the amyloid β peptide, and the formation of neurofibrillary tangles by hyperphosphorylated tau. A second, burgeoning theory by which to explain AD is based on the infection hypothesis. Much experimental and epidemiological data support the involvement of infections in the development of dementia. According to this mechanism, the infection either directly or via microbial virulence factors precedes the formation of amyloid β plaques. The amyloid β peptide, possessing antimicrobial properties, may be beneficial at an early stage of AD, but becomes detrimental with the progression of the disease, concomitantly with alterations to the innate immune system at both the peripheral and central levels. Infection results in neuroinflammation, leading to, and sustained by, systemic inflammation, causing eventual neurodegeneration, and the senescence of the immune cells. The sources of AD-involved microbes are various body microbiome communities from the gut, mouth, nose, and skin. The infection hypothesis of AD opens a vista to new therapeutic approaches, either by treating the infection itself or modulating the immune system, its senescence, or the body's metabolism, either separately, in parallel, or in a multi-step way.

Factors associated with immunosenescence during early adulthood in HIV-infected patients after durable efficient combination antiretroviral therapy

Perinatally HIV-infected patients face the consequences of both chronic infection effects per se and long-term combination antiretroviral therapy (cART) on immunosenescence. Aims of our study were to evaluate which factors independently contribute to immunosenescence in HIV-infected young adults with a very different HIV infection duration (perinatally HIV-infected young individuals -pHIVy- and age-matched non perinatally HIV-infected youths –npHIVy), after durable  efficient cART. We considered low thymic and bone marrow output, respectively evaluated by quantifying T-cell receptor excision circles (TRECs), K-deleting recombination excision circles (KRECs), and shorter telomeres lenght (TL) as surrogate biomarkers of immunosenescence. Twenty-one pHIVy and 19 npHIVy (with a mean HIV duration of 3–8 years) were included; mean age was 27 years for both groups. Immunosenescence biomarkers were comparable between pHIVy and npHIVy (despite longer HIV-infection, higher frequency of AIDS events, past cART-free periods and concomitant chronic viral infections in pHIVy). At the multivariate analysis, CD4+ was the only variable independently associated with TRECs and TL. Our data suggest that a good level of thymic activity can compensate the deleterious effects of past periods without cART, if HIV replication is suppressed for a sufficient time.

Age-related factors that affect B cell responses to vaccination in mice and humans

Aging significantly changes the ability to respond to vaccinations and infections. In this review, we summarize published results on age-related changes in response to infection with the influenza virus and on the factors known to increase influenza risk infection leading to organ failure and death. We also summarize how aging affects the response to the influenza vaccine with a special focus on B cells, which have been shown to be less responsive in the elderly. We show the cellular and molecular mechanisms contributing to the dysfunctional immune response of the elderly to the vaccine against influenza. These include a defective interaction of helper T cells (CD4+) with B cells in germinal centers, changes in the microenvironment, and the generation of immune cells with a senescence-associated phenotype. Finally, we discuss the effects of aging on metabolic pathways and we show how metabolic complications associated with aging lead to immune dysfunction.

Race/Ethnic and Educational Disparities in the Association Between Pathogen Burden and a Laboratory-Based Cumulative Deficits Index

BACKGROUND

Disparities in adult morbidity and mortality may be rooted in patterns of biological dysfunction in early life. We sought to examine the association between pathogen burden and a cumulative deficits index (CDI), conceptualized as a pre-clinical marker of an unhealthy biomarker profile, specifically focusing on patterns across levels of social disadvantage.

METHODS

Using the data from the National Health and Nutrition Examination Survey 2003-2004 wave (aged 20-49 years), we examined the association of pathogen burden, composed of seven pathogens, with the CDI. The CDI comprised 28 biomarkers corresponding to available clinical laboratory measures. Models were stratified by race/ethnicity and education level.

RESULTS

The CDI ranged from 0.04 to 0.78. Nearly half of Blacks were classified in the high burden pathogen class compared with 8% of Whites. Among both Mexican Americans and other Hispanic groups, the largest proportion of individuals were classified in the common pathogens class. Among educational classes, 19% of those with less than a high school education were classified in the high burden class compared with 7% of those with at least a college education. Blacks in the high burden pathogen class had a CDI 0.05 greater than those in the low burden class (P < 0.05). Whites in the high burden class had a CDI only 0.03 greater than those in the low burden class (P < 0.01).

DISCUSSION

Our findings suggest there are significant social disparities in the distribution of pathogen burden across race/ethnic groups, and the effects of pathogen burden may be more significant for socially disadvantaged individuals.

Network topology dynamics of circulating biomarkers and cognitive performance in older Cytomegalovirus-seropositive or -seronegative men and women

Background

Cytokines are signaling molecules operating within complex cascade patterns and having exceptional modulatory functions. They impact various physiological processes such as neuroendocrine and metabolic interactions, neurotrophins’ metabolism, neuroplasticity, and may affect behavior and cognition. In our previous study, we found that sex and Cytomegalovirus (CMV)-serostatus may modulate levels of circulating pro- and anti-inflammatory cytokines, metabolic factors, immune cells, and cognitive performance, as well as associations between them.

Results

In the present study, we used a graph-theoretical approach to investigate the network topology dynamics of 22 circulating biomarkers and 11 measures of cognitive performance in 161 older participants recruited to undergo a six-months training intervention. For network construction, we applied coefficient of determination (R²) that was calculated for all possible pairs of variables (N = 33) in four groups (CMV⁻ men and women; CMV⁺ men and women). Network topology has been evaluated by clustering coefficient (CC) and characteristic path length (CPL) as well as local (E_local) and global (E_global) efficiency, showing the degree of network segregation (CC and E_local) and integration (CPL and E_global). We found that networks under consideration showed small-world networks properties with more random characteristics. Mean CC, as well as local and global efficiency were highest and CPL shortest in CMV⁻ males (having lowest inflammatory status and highest cognitive performance). CMV⁻ and CMV⁺ females did not show any significant differences. Modularity analyses showed that the networks exhibit in all cases highly differentiated modular organization (with Q-value ranged between 0.397 and 0.453).

Conclusions

In this work, we found that segregation and integration properties of the network were notably stronger in the group with balanced inflammatory status. We were also able to confirm our previous findings that CMV-infection and sex modulate multiple circulating biomarkers and cognitive performance and that balanced inflammatory and metabolic status in elderly contributes to better cognitive functioning. Thus, network analyses provide a useful strategy for visualization and quantitative description of multiple interactions between various circulating pro- and anti-inflammatory biomarkers, hormones, neurotrophic and metabolic factors, immune cells, and measures of cognitive performance and can be in general applied for analyzing interactions between different physiological systems.

Cellular aging over 13 years associated with incident antinuclear antibody positivity in the Baltimore Longitudinal Study of Aging

Age-associated increases in antinuclear antibodies (ANA) in the general population are commonly noted but the mechanisms underlying this observation are unclear. This study aims to evaluate whether shorter peripheral blood mononuclear cell (PBMC) telomere length, a marker of more advanced biological age, is associated with ANA positivity prevalence and incidence in middle and older aged autoimmune disease-free individuals from the Baltimore Longitudinal Study of Aging (BLSA). Telomere length was measured by Southern Blot and categorized into tertiles. ANA was measured in a 1:80 and a 1:160 dilution of sera by immunofluorescence using HEp-2 cells (seropositive = 3 or 4). Multiple logistic regression was used to estimate the odds ratios and 95% confidence intervals of ANA positivity comparing the shorter tertiles of telomere length to the longest tertile for two cross-sectional points in time and then longitudinally to assess the association between shorter telomere length and incident ANA positivity. Cross-sectional analyses were adjusted for sex, race and BMI (N = 368 baseline, N = 370 follow-up) and longitudinal analyses were adjusted for sex, race, BMI and time between baseline and follow-up (N = 246). No statistically significant cross-sectional associations were observed at baseline or follow-up. Among those where ANA negative at baseline, individuals with shorter telomeres were more likely to be ANA positive at follow-up, an average 13 years later. Individuals with short telomeres at both time periods were more likely to be ANA positive. Findings suggest that ANA positivity in the general population may be indicative of immune dysfunction resulting from advanced cellular aging processes.

Research progress on immune aging and its mechanisms affecting geriatric diseases

Immunosenescence, also known as immune aging, refers to the degeneration, compensation, and reconstruction of the immune system with aging. Immune aging is an important factor in the increased susceptibility of the elderly to infectious diseases, malignant tumors, and a variety of chronic diseases and has long been a hotspot in geriatrics and immunology research. In this paper, the characteristics and progression of immune aging are briefly reviewed for clinicians' reference.

Allostatic stress load and CMV serostatus impact immune response to maximal exercise in collegiate swimmers

Collegiate athletes are exposed to varying levels of academic and physical stressors, placing them at increased risk for stress-activated latent viral infections. However, the impact of allostatic stress load on the immune response to maximal exercise in athletes remains largely unknown. This study examined the effects of a 7-mo training period and cytomegalovirus (CMV) serostatus on immune cell response to high-intensity swim tests within a group of collegiate swimmers. Samples were collected from 15 National Collegiate Athletic Association Division I swimmers (9 men, 6 women: 19.87 ± 0.64 yr) before and after exhaustive in-pool swims at 2 time points (V₁: immediately post-season 1 and V₃: beginning of season 2). An additional off-season (V₂) time point was collected in a subset of 9 swimmers. Natural killer (NK) cell, B cell, and T cells were quantified by flow cytometry. Linear mixed models were used to determine the effects of exercise, time point, and CMV serostatus (α = 0.05). Resting senescent CD8+ T cells were higher in CMV-seropositive participants at V₃ (P = 0.005). CMV-seronegative participants had a decrease in resting senescent CD8+ T cells from V₁ to V₃ (P = 0.021). After acute exercise, CMV-seropositive participants had lower naïve CD8+ T cells (P < 0.001) and higher senescent CD8+ T cells (P < 0.001). Increased cumulative stress levels did not appear to affect B-cell and NK-cell compartments. Immune response to exercise was impacted by CMV serostatus and allostatic stress load. Young CMV-seropositive athletes exposed to elevated stressors should be monitored to determine long-term effects of training and academic stressors.NEW & NOTEWORTHY Allostatic stress load is associated with impaired immune response to maximal exercise in cytomegalovirus (CMV)-seropositive subjects but not in CMV-seronegative young healthy adults.

Immunosenescence and Its Hallmarks: How to Oppose Aging Strategically? A Review of Potential Options for Therapeutic Intervention

Aging is accompanied by remodeling of the immune system. With time, this leads to a decline in immune efficacy, resulting in increased vulnerability to infectious diseases, diminished responses to vaccination, and a susceptibility to age-related inflammatory diseases. An age-associated immune alteration, extensively reported in previous studies, is the reduction in the number of peripheral blood naïve cells, with a relative increase in the frequency of memory cells. These two alterations, together with inflamm-aging, are considered the hallmarks of immunosenescence. Because aging is a plastic process, it is influenced by both nutritional and pharmacological interventions. Therefore, the role of nutrition and of immunomodulation in immunosenescence is discussed, due to the multifactorial influence on these hallmarks. The close connection between nutrition, intake of bioactive nutrients and supplements, immune function, and inflammation demonstrate the key role of dietary strategies as regulators of immune response and inflammatory status, hence as possible modulators of the rate of immunosenescence. In addition, potential options for therapeutic intervention are clarified. In particular, the use of interleukin-7 as growth factor for naïve T cells, the function of checkpoint inhibitors in improving T cell responses during aging and, the potential of drugs that inhibit mitogen-activated protein kinases and their interaction with nutrient signaling pathways are discussed. Finally, it is suggested that the inclusion of appropriate combinations of toll-like receptor agonists may enhance the efficacy of vaccination in older adults.

Age related human T cell subset evolution and senescence

T cells are fundamental effector cells against viruses and cancers that can be divided into different subsets based on their long-term immune protection and immediate immune response effects. The percentage and absolute number of these subsets change with ageing, which leads to a reduced immune response in older individuals. Stem cell memory T cells (T_SCM) represent a small population of memory T cells with enhanced proliferation and differentiation properties that are endowed with high potential for maintaining T cell homeostasis. However, whether these cells change with ageing and gender remains unknown. Here, we assayed the distribution of T_SCM and other T cell subsets in peripheral blood from 92 healthy subjects (44 females and 48 males) ranging from 3 to 88 years old by flow cytometry. We found that CD4+ and CD8+ T_SCM in the circulation have relatively stable frequencies, and the absolute number of CD8+ T_SCM decreased with age; however, the ratio of T_SCM to the CD4+ or CD8+ naïve population increased with age. Unlike the obvious changes in other T cell subsets with age and gender, the stable level of T_SCM in peripheral blood may support their capacity for sustaining long-term immunological memory, while their importance may increase together with ageing.

Effect of whole foods and dietary patterns on markers of subclinical inflammation in weight-stable overweight and obese adults: a systematic review

Context

Reduction of subclinical inflammation is a potential target for chronic disease management. Adiposity is a known modifier of meta-inflammation; however, the influence of dietary factors is less clear.

Objective

This review examines evidence from human trials evaluating effects of whole foods or dietary patterns on circulating inflammatory markers in weight-stable overweight and obese adults. It is the first review to investigate effects of diet on inflammation, independent of changes in adiposity.

Data Sources

The Ovid MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched.

Data Extraction

Data extraction was conducted using the Cochrane Collaboration Handbook for Systematic Reviews of Interventions.

Data Analysis

Study quality was evaluated using the Cochrane Collaboration Risk of Bias Assessment tool. Thirty-three studies were included assessing effects of 17 foods and dietary patterns on 39 inflammatory markers.

Conclusions

Overall, foods and dietary patterns were not found to have significant effects on inflammatory markers in weight-stable individuals. Inconsistencies among studies were largely due to methodological limitations. Future research should invest in longer intervention periods and standardization of inflammatory marker panels paired with novel technologies, while ensuring anthropometric measures are monitored and adequately controls are used.

Systematic Review Registration

Prospero registration number CRD42017067765.

Impact of CMV upon immune aging: facts and fiction

Aging is accompanied by significant defects in immunity and compromised responses to new, previously unencountered microbial pathogens. Most humans carry several persistent or latent viruses as they age, interacting with the host immune systems for years. In that context maybe the most studied persistent virus is Cytomegalovirus, infamous for its ability to recruit very large T cell responses which increase with age and to simultaneously evade elimination by the immune system. Here we will address how lifelong CMV infection and the immunological burden of its control might affect immune reactivity and health of the host over time.

A Longitudinal Study of the Association Between Persistent Pathogens and Incident Depression Among Older U.S. Latinos

Depression is estimated to affect more than 6.5 million Americans 65 years of age and older and compared with non-Latino whites older U.S. Latinos have a greater incidence and severity of depression, warranting further investigation of novel risk factors for depression onset among this population. We used data on 771/1,789 individuals ≥60 years of age from the Sacramento Area Latino Study on Aging (1998-2008) who were tested for cytomegalovirus (CMV), herpes simplex virus, varicella zoster, Helicobacter pylori, Toxoplasma gondii, and C-reactive protein (CRP) and interleukin-6 (IL-6) level. Among those without elevated depressive symptoms at baseline, we examined the association between each pathogen, inflammatory markers and incident depression over up to nearly 10 years of follow-up using discrete-time logistic regression. We found that only CMV seropositivity was statistically significantly associated with increased odds of incident depression (odds ratio [OR]: 1.38, 95% confidence interval [CI]: 1.00-1.90) in the total sample as well as among women only (OR: 1.70, 95% CI: 1.01-2.86). These associations were not mediated by CRP or IL-6 levels. Our findings suggest that CMV seropositivity may serve as an important risk factor for the onset of depression among older U.S. Latinos, but act outside of inflammatory pathways.

Effects of bariatric surgery on telomere length and T-cell aging

BACKGROUND

Obesity adversely affects health and is associated with subclinical systemic inflammation and features of accelerated aging, including the T-cell immune system. The presence of metabolic syndrome (MetS) may accelerate, while bariatric surgery might reverse these phenomena. To examine the effects of MetS and bariatric surgery on T-cell aging, we measured relative telomere length (RTL) and T-cell differentiation status in obese patients before and after bariatric surgery.

METHODS

WHO II/III classified obese patients scheduled for bariatric surgery were included: 41 without MetS and 67 with MetS. RTL and T-cell differentiation status were measured in circulating CD4⁺ and CD8⁺ T cells via flow cytometry. T-cell characteristics were compared between patients with and without MetS prior to and at 3, 6, and 12 months after surgery considering effects of age, cytomegalovirus-serostatus, and weight loss.

RESULTS

Thymic output, represented by numbers of CD31-expressing naive T cells, showed an age-related decline in patients with MetS. MetS significantly enhanced CD8⁺ T-cell differentiation. Patients with MetS had significant lower CD4⁺ RTL than patients without MetS. Within the first 6 months after bariatric surgery, RTL increased in CD4⁺ T cells after which it decreased at month 12. A decline in both thymic output and more differentiated T cells was seen following bariatric surgery, more pronounced in the MetS group and showing an association with percentage of body weight loss.

CONCLUSIONS

In obese patients, MetS results in attrition of RTL and accelerated T-cell differentiation. Bariatric surgery temporarily reverses these effects. These data suggest that MetS is a risk factor for accelerated aging of T cells and that MetS should be a more prominent factor in the decision making for eligibility for bariatric surgery.

Combined Plasma Elevation of CRP, Intestinal-Type Fatty Acid-Binding Protein (I-FABP), and sCD14 Identify Older Patients at High Risk for Health Care-Associated Infections

Background

We hypothesized that low-grade inflammation was driven by microbial translocation and associated with an increased risk of health care-associated infections (HAIs).

Methods

We included 121 patients aged 75 years or over in this prospective cohort study. High-sensitivity C-reactive protein (hs-CRP), I-FABP, and sCD14-as markers for low-grade inflammation, intestinal epithelial barrier integrity, and monocyte activation, respectively-were measured at admission.

Results

HAIs occurred during hospitalization in 62 (51%) patients. Elevated hs-CRP (≥6.02 mg/L, ie, the median) was associated with a significantly higher HAI risk when I-FABP was in the highest quartile (odds ratio [OR], 4; 95% confidence interval [95% CI], 1.39-11.49; p = .010). In patients with hs-CRP elevation and highest-quartile I-FABP, sCD14 elevation (≥0.65 µg/mL, ie, the median) was associated with an 11-fold higher HAI risk (OR, 10.8; 95% CI, 2.28-51.1; p = .003). Multivariate analyses adjusted for invasive procedures and comorbidities did not change the associations linking the three markers to the HAI risk.

Conclusion

Increased levels of hs-CRP, I-FABP, and sCD14 may reflect loss of intestinal epithelial barrier integrity with microbial translocation leading to monocyte activation and low-grade inflammation. In our cohort, these markers identified patients at high risk for HAIs.

Expanded peripheral CD4+CD28null T cells and its association with atherosclerotic changes in patients with end stage renal disease on hemodialysis

End-stage renal disease (ESRD) patients, including those on hemodialysis, possess a high risk for cardiovascular diseases, as the first leading cause of death among them. Traditional risk factors do not utterly elucidate this. Throughout the last two decades, CD4⁺CD28^null T cells; an unusual subset of T lymphocytes, was detected high with excess cardiovascular (CV) mortality. We aimed to investigate the circulating CD4⁺CD28^null T cells frequency in ESRD patients on hemodialysis and to evaluate their relationship with atherosclerotic changes. High-resolution carotid ultrasonography was done to assess the common carotid artery intima media thickness in a number of ESRD patients, accordingly patients were selected and subdivided into two groups; 30 with atherosclerosis (mean [SD] age, 51.6 [6.3] years) and 30 without (mean [SD] age, 48.9 [5.5] years). Another 30 healthy individuals (mean [SD] age, 48.5 [6.8] years) were enrolled. Analysis of CD4⁺CD28^null T-cells frequency by flow-cytometry was performed in all studied subjects. CD4⁺CD28^null T cell percentage was significantly higher in ESRD patients, (mean [SD], 7.3 [2.7] %) compared to healthy individuals (mean [SD], 3.0 [0.8] %), (p < 0.001). Additionally, the expansion of these unusual T lymphocytes was significantly higher in ESRD patients with atherosclerotic changes (mean [SD], 9.47 [0.75] %) compared to those without atherosclerosis (mean [SD], 5.22 [2.14] %), (p < 0.001). In conclusion circulating CD4⁺CD28^null T lymphocyte population showed expansion in ESRD patients, and of interest in correlation to preclinical atherosclerotic changes.

Association between human herpes virus seropositivity and frailty in the elderly: A systematic review and meta-analysis

Frailty is an emerging geriatric syndrome characterized by decreased physiologic reserve and increased vulnerability to environmental factors. Several studies have examined the association between persistent cytomegalovirus (CMV) infection and poor clinical outcomes in the elderly, but the results are often contradictory. Here, we performed a systematic review and meta-analysis to analyze the association between human herpesvirus seropositivity [CMV, Epstein-Barr virus (EBV), Varicella zoster virus (VZV), and Herpes simplex virus (HSV)] and frailty in elderly people. Searches were performed in PubMed, SCOPUS, Lilacs, IBECS, and Web of Science databases. We used the odds ratio (OR) as a measure of the association between herpesvirus infections and frailty. Summary estimates were calculated using random-effects models. Six studies were included in the present systematic review. The data from 2559 elderly subjects were analyzed; 1571 of the subjects had ages between 60 and 79 years, and 988 of the subjects were older than 80. We found an association between CMV seropositivity and frailty in the elderly aged 60-79 years (OR 2.33, CI 95% 1.48-3.67) but not in the oldest-old subjects (OR 0.67, CI 95% 0.42-1.05). Moreover, no association was found between EBV, VZV, and HSV infections and frailty. Current evidence suggests an association between CMV seropositivity and frailty in individuals aged 60-79 years old.

An immunological age index in bipolar disorder: A confirmatory factor analysis of putative immunosenescence markers and associations with clinical characteristics

OBJECTIVES

The study aims to generate an immunological age (IA) trait on the basis of immune cell differentiation parameters, and to test whether the IA is related to age and disease characteristics.

METHODS

Forty-four euthymic type I bipolar disorder patients were included in this study. Five immunosenescence-related parameters were assessed: proportions of late-differentiated cells (e.g., CD3+CD8+CD28-CD27- and CD3-CD19+IgD-CD27-), and the expression of CD69, CD71, and CD152 after stimulation. Confirmatory factor analysis was applied to generate an IA trait underling the 5 measures.

RESULTS

The best-fit model was constituted by 4 parameters that were each related to an underlying IA trait, with 1 cell population positively correlated (CD3+CD8+CD28-CD27- [λ = 0.544, where λ represents the loading of the parameter onto the IA trait] and 3 markers negatively correlated (CD69 [λ = -0.488], CD71 [λ = -0.833], and CD152 [λ = -0.674]). The IA trait was associated with chronological age (β = 0.360, p = .013) and the number of previous mood episodes (β = 0.426, p = .006). In a mediation model, 84% of the effect between manic episodes, and IA was mediated by body mass index.

CONCLUSION

In bipolar disorder type I, premature aging of the immune system could be reliably measured using an index that validated against chronological age, which was related to adverse metabolic effects of the disease course.

Social networks in relation to self-reported symptomatic infections in individuals aged 40-75 - the Maastricht study

Background

Most infections are spread through social networks (detrimental effect). However, social networks may also lower infection acquisition (beneficial effect). This study aimed to examine associations between social network parameters and prevalence of self-reported upper and lower respiratory, gastrointestinal and urinary tract infections in a population aged 40–75.

Methods

In this population-based cross-sectional cohort study (N = 3004, mean age 60.0 ± 8.2 years, 49% women), infections within the past two months were assessed by self-administered questionnaires. Social network parameters were assessed using a name generator questionnaire. To examine the associated beneficial and detrimental network parameters, univariable and multivariable logistic regression was used.

Results

Participants reported an average of 10 people (alters) with whom they had 231 contacts per half year. Prevalences were 31.1% for upper respiratory, 11.5% for lower respiratory, 12.5% for gastrointestinal, and 5.7% for urinary tract infections. Larger network size, and a higher percentage of alters that were friends or acquaintances were associated with higher odds of upper respiratory, lower respiratory and/or gastrointestinal infections (detrimental). A higher total number of contacts, higher percentages of alters of the same age, and higher percentages of family members/acquaintances were associated with lower odds of upper respiratory, lower respiratory and/or gastrointestinal infections (beneficial).

Conclusion

We identified both detrimental and beneficial associations of social network parameters with the prevalence of infections. Our findings can be used to complement mathematical models on infection spread, as well as to optimize current infectious disease control.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3197-3) contains supplementary material, which is available to authorized users.

Differences in the association between persistent pathogens and mood disorders among young- to middle-aged women and men in the U.S

BACKGROUND

A growing literature supports the role of immune system alterations in the etiology of mood regulation, yet there is little population-based evidence regarding the association between persistent pathogens, inflammation and mood disorders among younger women and men in the U.S.

METHODS

We used data from the National Health and Nutrition Examination Survey III on individuals 15-39 years of age assessed for major depression, dysthymia, and/or bipolar disorder I and tested for cytomegalovirus (N=6825), herpes simplex virus (HSV)-1 (N=5618) and/or Helicobacter pylori (H. pylori) (N=3167) seropositivity as well as C-reactive protein (CRP) level (N=6788). CMV immunoglobulin G (IgG) antibody level was also available for a subset of women (N=3358). We utilized logistic regression to estimate the odds ratio (OR) and 95% confidence interval (CI) for the association between pathogens, CRP levels and each mood disorder overall and among women and men, separately.

RESULTS

H. pylori seropositivity was associated with increased odds of dysthymia (OR 2.37, 95% confidence interval (CI): 1.07, 5.24) among women, but decreased odds among men (OR 0.51, 95% CI: 0.28, 0.92). CMV seropositivity was also associated with lower odds of depression (OR 0.54, 95% CI: 0.32, 0.91) among men, while elevated CMV IgG level was marginally associated with increased odds of mood disorders among women. Associations were not mediated by CRP level.

CONCLUSIONS

Our findings suggest that persistent pathogens such as CMV and H. pylori may differentially influence mood disorders among women and men, warranting further investigation into biological and/or sociocultural explanations for the contrasting associations observed.