The unmet need in the elderly: how immunosenescence, CMV infection, co-morbidities and frailty are a challenge for the development of more effective influenza vaccines

Ageing and obesity similarly impair antibody responses

Ageing is characterized by increased low-grade chronic inflammation, which is a significant risk factor for morbidity and mortality of elderly individuals. Similar to ageing, obesity is considered to be an inflammatory predisposition associated with chronic activation of immune cells and consequent local and systemic inflammation. Both ageing and obesity are characterized by reduced innate and adaptive immune responses. This review focuses on B cells, how they may contribute, at least locally, to low-grade chronic inflammation in ageing and obesity and on the mechanisms involved.

Preserved antiviral adaptive immunity following polyclonal antibody immunotherapy for severe murine influenza infection

Passive immunotherapy may have particular benefits for the treatment of severe influenza infection in at-risk populations, however little is known of the impact of passive immunotherapy on the formation of memory responses to the virus. Ideally, passive immunotherapy should attenuate the severity of infection while still allowing the formation of adaptive responses to confer protection from future exposure. In this study, we sought to determine if administration of influenza-specific ovine polyclonal antibodies could inhibit adaptive immune responses in a murine model of lethal influenza infection. Ovine polyclonal antibodies generated against recombinant PR8 (H1N1) hemagglutinin exhibited potent prophylactic capacity and reduced lethality in an established influenza infection, particularly when administered intranasally. Surviving mice were also protected against reinfection and generated normal antibody and cytotoxic T lymphocyte responses to the virus. The longevity of ovine polyclonal antibodies was explored with a half-life of over two weeks following a single antibody administration. These findings support the development of an ovine passive polyclonal antibody therapy for treatment of severe influenza infection which does not affect the formation of subsequent acquired immunity to the virus.

Disorganization of the splenic microanatomy in ageing mice

The precise mechanisms responsible for immunosenescence still remain to be determined, however, considering the evidence that disruption of the organization of primary and secondary lymphoid organs results in immunodeficiency, we propose that this could be involved in the decline of immune responses with age. Therefore, we investigated the integrity of the splenic microarchitecture in mice of increasing age and its reorganization following immune challenge in young and old mice. Several differences in the anatomy of the spleen with age in both the immune and stromal cells were observed. There is an age-related increase in the overall size of the white pulp, which occurs primarily within the T-cell zone and is mirrored by the enlargement of the T-cell stromal area, concurrent to the distinct boundary between T cells and B cells becoming less defined in older mice. In conjunction, there appears to be a loss of marginal zone macrophages, which is accompanied by an accumulation of fibroblasts in the spleens from older animals. Furthermore, whereas the reorganization of the white pulp is resolved after several days following antigenic challenge in young animals, it remains perturbed in older subjects. All these age-related changes within the spleen could potentially contribute to the age-dependent deficiencies in functional immunity.

T-Cell Immunity to Influenza in Older Adults: A Pathophysiological Framework for Development of More Effective Vaccines

One of the most profound public health consequences of immune senescence is reflected in an increased susceptibility to influenza and other acute respiratory illnesses, as well as a loss of influenza vaccine effectiveness in older people. Common medical conditions and mental and psychosocial health issues as well as degree of frailty and functional dependence accelerate changes associated with immune senescence. All contribute to the increased risk for complications of influenza infection, including pneumonias, heart diseases, and strokes that lead to hospitalization, disability, and death in the over 65 population. Changes in mucosal barrier mechanisms and both innate and adaptive immune functions converge in the reduced response to influenza infection, and lead to a loss of antibody-mediated protection against influenza with age. The interactions of immune senescence and reduced adaptive immune responses, persistent cytomegalovirus infection, inflammaging (chronic elevation of inflammatory cytokines), and dysregulated cytokine production, pose major challenges to the development of vaccines designed to improve T-cell-mediated immunity. In older adults, the goal of vaccination is more realistically targeted to providing clinical protection against disease rather than to inducing sterilizing immunity to infection. Standard assays of antibody titers correlate with protection against influenza illness but do not detect important changes in cellular immune mechanisms that correlate with vaccine-mediated protection against influenza in older people. This article will discuss: (i) the burden of influenza in older adults and how this relates to changes in T-cell function, (ii) age-related changes in different T-cell subsets and immunologic targets for improved influenza vaccine efficacy in older, and (iii) the development of correlates of clinical protection against influenza disease to expedite the process of new vaccine development for the 65 and older population. Ultimately, these efforts will address the public health need for improved protection against influenza in older adults and “vaccine preventable disability.”

The Effectiveness of Influenza Vaccination in Different Groups

Annual administration of the seasonal influenza vaccine, especially to persons known to be at elevated risk for developing serious complications, is the focus of current efforts to reduce the impact of influenza. The main factors influencing estimated inactivated influenza vaccine efficacy and effectiveness, the results obtained in different population groups, current vaccination strategies and the possible advantages of new vaccines are discussed. The available evidence suggests that influenza vaccines are less effective in the elderly than in young adults, but vaccination is encouraged by public health institutions due to higher mortality and complications. There is no consensus on universal vaccination of children yet economic studies suggest that yearly paediatric vaccination is cost saving. The benefits of herd immunity generated by paediatric vaccination require further study. Newer vaccines should be more and more-broadly protective, stable, easy to manufacture and administer and highly immunogenic across all population groups.

Inflammaging decreases adaptive and innate immune responses in mice and humans

Both the innate and adaptive immune systems decline with age, causing greater susceptibility to infectious diseases and reduced responses to vaccination. Diseases are more severe in elderly than in young individuals and have a greater impact on health outcomes such as morbidity, disability and mortality. Aging is characterized by increased low-grade chronic inflammation, called "inflammaging", measured by circulating levels of TNF-α, IL-6 and CRP, as well as by latent infections with viruses such as cytomegalovirus. Inflammaging has received considerable attention because it proposes a link between changes in immune cells and a number of diseases and syndromes typical of old age. In this review we aim at summarizing the current knowledge on pathways contributing to inflammaging, on immune responses down-regulated by inflammation and mechanisms proposed. The defects in the immune response of elderly individuals presented in this review should help to discover avenues for effective intervention to promote healthy aging.

B Cell-Specific Biomarkers for Optimal Antibody Responses to Influenza Vaccination and Molecular Pathways That Reduce B Cell Function with Aging

This review highlights recent findings on the effects of aging on influenza vaccine responses, with major emphasis on T and B cells, which are significantly impaired by aging. We discuss changes in T cell production and thymic output; T cell subsets; and TCR repertoire, function, and response to latent persistent infection. We also discuss changes in B cell subsets, repertoire, and function, and how function is impaired by increased intrinsic B cell inflammation and reduced signal transduction. This review presents age-related effects on antigen-presenting cells, summarizes recent studies, including our own, aimed at the identification of biomarkers of protective vaccine responses, and provides examples of recent technical advances and insights into human vaccine responses that are helping to define the features associated with successful vaccination and that may enable a more predictive vaccinology in the future.

Telomere Length as an Indicator of the Robustness of B- and T-Cell Response to Influenza in Older Adults

BACKGROUND

Telomeres provide a key mechanism for protecting the integrity of chromosomes and their attrition after cell division and during aging are evident in lymphocytes. However, the significance of telomere shortening in age-associated decline of immune function is unknown.

METHODS

We selected 22 HLA-A2-positive healthy older adults who have relatively short or long telomere lengths to compare their antibody response against the influenza vaccine, and their CD8(+) T-cell response against an influenza antigen.

RESULTS

B cells from individuals with a robust antibody response to the influenza vaccine had significantly longer telomeres than those with a poor antibody response. Monocyte-derived antigen-presenting cells of both short and long telomere groups induced similar expansions of influenza M1-specific CD8(+) T cells. Vaccination did not increase M1-specific CD8(+) T cells in blood, but M1-specific CD8(+) T cells from the long telomere group exhibited significantly greater expansion in vitro than those from the short telomere group. Finally, M1-specific CD8(+) T cells that underwent more expansions had significantly longer telomeres than cells with fewer divisions.

CONCLUSIONS

Telomere length is positively associated with a robust lymphocyte response, and telomere attrition may contribute to the age-associated decline of adaptive immunity.

Thymic emigration patterns in patients with type 2 diabetes treated with metformin

Recent data suggest that thymic output, which provides the naive T cells necessary for the normal functioning of T-cell-dependent immunosurveillance cellular immunity including anti-cancer protection, can be disturbed in the course of type 2 diabetes. Metformin, an anti-diabetic drug commonly confirmed as an agent with many potential anti-cancer activities, might be helpful in this immune correction. The profile of thymic output was evaluated in the current study on the basis of the signal-joint T-cell receptor excision circle (sjTREC) concentration in peripheral blood polymorphonuclear cells and thymic emigrant content in peripheral blood evaluated from CD127 and/or CD132 antigen expression. It was revealed that recent thymic emigrants and more differentiated CD127(+) CD132(+) cell populations were decreased among naive T cells and CD8(+) T cells, whereas RTE count was increased in CD4(+) T cells, and the CD127(+) CD132(+) cell population was less numerous than in non-diabetic participants. Terminally differentiated thymic emigrants, i.e. CD127(-) CD132(+) cells, were increased in naive T cells and in CD8(+) T cells. Metformin affects mainly the early phases of thymic export, increasing CD127(+) CD132(-) and CD127(+) CD132(+) cell populations in naive T cells and the CD127(+) CD132(-) population in CD4(+) T lymphocytes. It could be concluded that type 2 diabetes deteriorates thymic immunostasis. The decreased thymic output could be compensated by metformin, especially with regard to CD4(+) naive T cells. It is the first time that therapy with metformin has been documented by us as particularly useful in the control and normalization of thymus function, regarding correction of early populations of thymic emigrants.

Gene expression markers of age-related inflammation in two human cohorts

INTRODUCTION

Chronically elevated circulating inflammatory markers are common in older persons but mechanisms are unclear. Many blood transcripts (>800 genes) are associated with interleukin-6 protein levels (IL6) independent of age. We aimed to identify gene transcripts statistically mediating, as drivers or responders, the increasing levels of IL6 protein in blood at older ages.

METHODS

Blood derived in-vivo RNA from the Framingham Heart Study (FHS, n=2422, ages 40-92 yrs) and InCHIANTI study (n=694, ages 30-104 yrs), with Affymetrix and Illumina expression arrays respectively (>17,000 genes tested), were tested for statistical mediation of the age-IL6 association using resampling techniques, adjusted for confounders and multiple testing.

RESULTS

In FHS, IL6 expression was not associated with IL6 protein levels in blood. 102 genes (0.6% of 17,324 expressed) statistically mediated the age-IL6 association of which 25 replicated in InCHIANTI (including 5 of the 10 largest effect genes). The largest effect gene (SLC4A10, coding for NCBE, a sodium bicarbonate transporter) mediated 19% (adjusted CI 8.9 to 34.1%) and replicated by PCR in InCHIANTI (n=194, 35.6% mediated, p=0.01). Other replicated mediators included PRF1 (perforin, a cytolytic protein in cytotoxic T lymphocytes and NK cells) and IL1B (Interleukin 1 beta): few other cytokines were significant mediators.

CONCLUSIONS

This transcriptome-wide study on human blood identified a small distinct set of genes that statistically mediate the age-IL6 association. Findings are robust across two cohorts and different expression technologies. Raised IL6 levels may not derive from circulating white cells in age related inflammation.

A Novel Dynamic Model for Health Economic Analysis of Influenza Vaccination in the Elderly

Introduction

New vaccines are being developed to improve the efficacy of seasonal influenza immunization in elderly persons aged ≥65 years. These products require clinical and economic evaluation to aid policy decisions.

Methods

To address this need, a two-part model has been developed, which we have applied to examine the potential clinical and economic impact of vaccinating elderly persons with adjuvanted trivalent inactivated influenza vaccine (aTIV) relative to conventional trivalent (TIV) and quadrivalent (QIV) vaccines. We compared outcomes in the US population for (1) aTIV in persons aged ≥65 years and QIV in all other age cohorts; (2) QIV in all cohorts; (3) TIV in all cohorts. Low, average, and high intensity seasons with low, average, and high vaccine match scenarios were compared. Probabilistic sensitivity analysis was conducted within each discrete scenario to explore the impact of variation in model inputs on potential outcomes.

Results

Assuming current vaccination coverage rates in the US population with (a) 25% better efficacy of adjuvanted versus non-adjuvanted vaccine against any strain and (b) 35% better efficacy of non-adjuvanted vaccine against matched B versus mismatched B strains, use of aTIV in persons aged ≥65 years and QIV in persons <65 years could reduce influenza cases by 11,166–1,329,200, hospitalizations by 1365–43,674, and deaths by 421–11,320 versus use of QIV in all cohorts. These outcomes are reflected in a corresponding increase in quality-adjusted life-years (QALYs) of 3003–94,084. If the prevalence of mismatched influenza B was >54.5% of all circulating strains, use of QIV in all cohorts would offset the clinical benefits of aTIV. Elderly aTIV or QIV vaccination was associated with improved outcomes over non-adjuvanted TIV in many of the scenarios, particularly in low match seasons of any intensity. Total cost savings (including direct and indirect healthcare costs plus productivity impacts) with aTIV in the elderly versus QIV in the whole population ranged from $27 million (low intensity, low match) to $934 million (high intensity, high match). Univariate sensitivity analysis of relative vaccine prices in the average intensity, average match scenario indicated that aTIV could be marginally cost saving relative to QIV at the currently published Medicare price for influenza vaccines offering enhanced efficacy in the elderly. Elderly vaccination with aTIV was associated with a higher overall cost compared with TIV in only two scenarios (low intensity with average or high match); the incremental cost/QALY relative to TIV was $9980 in the average match scenario and $28,800 in the high match scenario.

Conclusions

Vaccination of persons aged ≥65 years with aTIV has the potential to provide clinical and economic benefit relative to QIV and TIV. The new model allows the assessment of various alternative strategies for available influenza vaccines.

Funding

Novartis Vaccines.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-015-0076-8) contains supplementary material, which is available to authorized users.

Current and next generation influenza vaccines: Formulation and production strategies

Vaccination is the most effective method to prevent influenza infection. However, current influenza vaccines have several limitations. Relatively long production times, limited vaccine capacity, moderate efficacy in certain populations and lack of cross-reactivity are important issues that need to be addressed. We give an overview of the current status and novel developments in the landscape of influenza vaccines from an interdisciplinary point of view. The feasibility of novel vaccine concepts not only depends on immunological or clinical outcomes, but also depends on biotechnological aspects, such as formulation and production methods, which are frequently overlooked. Furthermore, the next generation of influenza vaccines is addressed, which hopefully will bring cross-reactive influenza vaccines. These developments indicate that an exciting future lies ahead in the influenza vaccine field.

Immunostimulatory effects of RACK1 pseudosubstrate in human leukocytes obtained from young and old donors

Aims of this study were to investigate the ability of RACK1 pseudosubstrate alone or in combination with classical immune stimuli to activate human leukocytes, and to restore age-associated immune defects.A total of 25 donors (17 old donors, 77-79 yrs; 8 young donors, 25-34 yrs) were enrolled. To evaluate the effect of RACK1 pseudosubstrate on cytokine production and CD86 expression the whole blood assay was used. Cultures were treated with RACK1 pseudosubstrate in the presence or absence of lipopolysaccharide (LPS) or phytohaemagglutinin (PHA) and incubated for 24 h or 48 h for LPS-induced CD86 expression, TNF-α, IL-6, IL-8, IL-10 production, and PHA-induced IL-4, IL-10, IFN-γ, respectively. RACK1 pseudosubstrate alone induced IL-6, IL-8, and CD86 expression in both young and old donors, and IFN-γ in old donors. In combination with LPS an increase in IL-8, IL-10 and TNF-α was observed, also resulting in restoration of age-associated defective production, while no changes in the other parameters investigated were found.Even if based on a small sample size, these results suggest the possibility to by-pass some of age-associated immune alterations, which may be beneficial in situations were natural immune stimulation is required, and highlight a different role of PKCβ in immune cells activation.

Presence of circulating Her2-reactive CD8 + T-cells is associated with lower frequencies of myeloid-derived suppressor cells and regulatory T cells, and better survival in older breast cancer patients

Introduction

Breast cancer is one of the most common cancers among women. Its incidence is increasing in many countries and a higher number of older women are now being diagnosed with the disease. Immune parameters are implicated in disease progression, and the frequencies of both myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), associated with tumour burden, have been suggested to be indicators of poor prognosis in cases of metastatic breast cancer.

Methods

Here, we have assessed the frequency of peripheral Tregs and MDSCs in relation to in vitro T cell responses to Her2 antigen in 40 untreated breast cancer patients 65 to 87 years of age at diagnosis.

Results

The five-year survival rate of patients who mounted a CD8+ T cell response to Her2 peptides and had a lower frequency of Lin⁻CD14⁺HLA-DR⁻MDSCs was 100% compared to only 38% in patients without Her2-reactive CD8+ T cells and with higher frequencies of MDSCs (P = 0.03). Patients who lacked a CD8 response to Her2 tended to have higher frequencies of MDSCs. Similarly, patients who lacked a CD8 response to Her2 and had higher frequencies of CD4⁺Foxp3⁺CD127^lowCD25⁺ Tregs had only 50% survival compared to the 100% survival of patients who did mount a CD8 response and had lower frequencies of Tregs (P = 0.03). A similar trend was observed for activated (CD4⁺CD45RA⁻Foxp3^hi) but not resting Tregs (CD4⁺CD45RA⁺FoxP3⁺). This survival advantage was observed in both metastatic and non-metastatic patients.

Conclusions

Our data demonstrate a negative role of both MDSCs and Tregs in the prognosis of breast cancer patients, the mechanism of which might be through dampening favourable CD8+ T cell immune responses to tumour-associated antigens.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0541-z) contains supplementary material, which is available to authorized users.

Vaccination in the elderly: what can be recommended?

The age-associated increased susceptibility to infectious disease would suggest that vaccination should be a route to promote healthy aging and keep our seniors autonomous and independent. While vaccination represents a cost-effective and efficient strategy at community level, the ability of the immune system to mount a protective immune response is still unpredictable at the level of the individual. Thus, at a similar age, some individuals, including the elderly, might still be 'good' responders while some other, even younger, would definitely fail to mount a protective response. In this review, the current burden of vaccine-preventable diseases in the aging and aged population will be detailed with the aim to identify the ideal vaccine candidates over the age of 50 years. This article will conclude with potential strategies to reduce, as best as possible, this burden and the imperative need to overcome barriers in extending current vaccine coverage towards to a lifelong vaccine schedule.

Cytomegalovirus (CMV) seropositivity decreases B cell responses to the influenza vaccine

Cytomegalovirus (CMV)-seropositivity has been shown to have a negative effect on influenza vaccine-specific antibody responses. In this paper, we confirm and extend these results showing for the first time, a negative association between CMV-seropositivity and B cell predictive biomarkers of optimal vaccine responses. These biomarkers are switched memory B cells and AID in CpG-stimulated B cell cultures measured before vaccination which positively correlate with the serum response to the influenza vaccine. We also found that CMV-seropositivity is associated with increased levels of B cell-intrinsic inflammation and these both correlate with lower B cell function. Finally, CMV-seropositivity is associated with decreased percentages of individuals responding to the vaccine in both young and elderly individuals.

Predictors of the antibody response to influenza vaccination in older adults with type 2 diabetes

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic inflammatory diseases of the elderly. Its development is related to the alteration of the immune system with aging characterized by immunosenescence and inflamm-aging. In turn, T2DM also alters the immune response. As a consequence, older people with T2DM are more susceptible to influenza and to its complications as compared with healthy controls. Vaccination against influenza has shown poor efficacy in the older population and even less efficacy in patients with diabetes. We studied here the antibody response to vaccination in healthy and diabetic elderly participants.

RESEARCH DESIGN AND METHODS

In 2 groups of elderly participants (healthy N=119 and T2DM N=102), we measured the immunogenicity of influenza vaccine by hemagglutination inhibition assays. We assessed several blood and functional parameters as potential predictors of the vaccine efficacy.

RESULTS

We found no difference between antibody responses in diabetic elderly compared with healthy elderly. Among the biological and functional determinants, the cytomegalovirus (CMV) serostatus played a more prominent role in determining the magnitude of response. We concluded that in addition to age and diabetic status, immunological history such as CMV status should be taken into account. None of the other biological or functional parameters studied could be reliably linked to the vaccine antibody response in older adults who are not frail including those with well-controlled diabetes.

CONCLUSIONS

Our data strongly suggest that influenza vaccine should be administered to elderly patients with T2DM; however, the immune determinants of the antibody response to influenza vaccination should be further investigated.

On-label and off-label use of high-dose influenza vaccine in the United States, 2010-2012

High-dose inactivated, influenza vaccine was licensed by the FDA in December 2009 for adults aged 65 y and older. The ACIP did not issue or state a preference for a specific vaccine in the elderly population. The extent of its on-label and off-label use is unknown. Using the MarketScan Commercial Claims and Encounters and the Medicare Supplemental database, we identified individuals who received the high-dose influenza vaccine or the standard, seasonal trivalent influenza vaccine between January 1, 2010 and December 31, 2012. For people aged ≥65 y, we used multivariable regression to assess the association between patient and provider level variables and high-dose influenza vaccine versus standard influenza vaccine. We characterized all off-label high-dose vaccine administered to people younger than 65 y of age, and investigated whether sicker patients were targeted for off-label use by examining the association between various comorbid conditions and receipt of the high-dose vaccine among adults aged 18-64. Among patients aged ≥65 y who received an influenza vaccine, 18.4% received the high-dose vaccine. Uptake was minimal in 2010, but 25% and 32% of influenza shots were the high-dose formulation in 2011 and 2012, respectively. Almost 27,000 seniors received a second high-dose vaccine with a median of 368 d (IQR: 350-387 days) between doses. Older age, family practice physicians, and having PPO insurance were positively associated with receiving high-dose vaccine. There were 36,624 off-label high-dose vaccines administered. Half of the patients receiving off-label doses were aged 50-64. Adults aged 18-64 y receiving high-dose vaccine were more likely to have chronic comorbidities than people receiving standard influenza vaccine; however, there was not one specific illness that seemed to be targeted by physicians. In the first 3 y since licensure, use of the high-dose vaccine among seniors has been limited. The safety of this vaccine should be monitored closely among 2 groups of people - seniors receiving repeat doses and people <65.

Influence of the microbiome on response to vaccination

In order for vaccines to be effective within a given population not only do large numbers of people need to be vaccinated, but a large proportion of those vaccinated must develop protective immunity. The mechanisms that lead to a poor immune response to vaccination are complex and poorly understood, but include both genetic and environmental factors. The bacteria that exist throughout the human body, known as the microbiome, play a variety of roles in the development of the immune system. This is particularly true during infancy when the microbiome and the immune response are developing in tandem. Most vaccines are administered in early childhood to prevent outbreaks of devastating childhood diseases. Understanding the impact that the early microbiome plays in response to vaccination will improve our understanding of vaccine efficacy.

Detection of influenza A/H1N1-specific human IgG-secreting B cells in older adults by ELISPOT assay

B cells play an important role in humoral immunity and antibody production. Use of a B cell ELISPOT assay to quantify antigen-specific B cells can assist other assays to achieve a more complete profile of the humoral immune response after vaccination. We utilized a B cell ELISPOT assay to measure the number of influenza A/H1N1-specific B cells at key timepoints after seasonal influenza vaccination in 106 older adults (50-74 years of age). Blood was drawn from these subjects on Day 0, Day 3, Day 28, and Day 75 after vaccination to represent baseline, early, peak, and late response, respectively, of influenza A/H1N1-specific B cells. A significant increase in A/H1N1-specific B cells (median 36 spot-forming units/SFUs per 200,000 cells, p<0.0001) was seen on Day 28 compared to baseline and Day 3, and this number decreased (23 SFUs, p<0.0001) by Day 75, but not to baseline level. These data suggest that the B cell ELISPOT can be used to profile and monitor the humoral immune responses in older subjects after influenza vaccination, and serve as an immune signature marker.

Immune biomarkers predictive of respiratory viral infection in elderly nursing home residents

OBJECTIVE

To determine if immune phenotypes associated with immunosenescence predict risk of respiratory viral infection in elderly nursing home residents.

METHODS

Residents ≥ 65 years from 32 nursing homes in 4 Canadian cities were enrolled in Fall 2009, 2010 and 2011, and followed for one influenza season. Following influenza vaccination, peripheral blood mononuclear cells (PBMCs) were obtained and analysed by flow cytometry for T-regs, CD4+ and CD8+ T-cell subsets (CCR7+CD45RA+, CCR7-CD45RA+ and CD28-CD57+) and CMV-reactive CD4+ and CD8+ T-cells. Nasopharyngeal swabs were obtained and tested for viruses in symptomatic residents. A Cox proportional hazards model adjusted for age, sex and frailty, determined the relationship between immune phenotypes and time to viral infection.

RESULTS

1072 residents were enrolled; median age 86 years and 72% female. 269 swabs were obtained, 87 were positive for virus: influenza (24%), RSV (14%), coronavirus (32%), rhinovirus (17%), human metapneumovirus (9%) and parainfluenza (5%). In multivariable analysis, high T-reg% (HR 0.41, 95% CI 0.20-0.81) and high CMV-reactive CD4+ T-cell% (HR 1.69, 95% CI 1.03-2.78) were predictive of respiratory viral infection.

CONCLUSIONS

In elderly nursing home residents, high CMV-reactive CD4+ T-cells were associated with an increased risk and high T-regs were associated with a reduced risk of respiratory viral infection.

IFNγ⁻TNFα⁻IL2⁻MIP1α⁻CD107a⁺PRF1⁺ CD8 pp65-Specific T-Cell Response Is Independently Associated With Time to Death in Elderly Humans

Persistent cytomegalovirus (CMV) infection has been suggested to be a major driving force in the immune deterioration and an underlying source of age-related diseases in the elderly. CMV antibody titers are associated with lower responses to vaccination, cardiovascular diseases, frailty, and mortality. CMV infection is also associated with shorter T-cell telomeres and replicative senescence. Although an age-related deregulation of CMV-specific T-cell responses could be an underlying cause of the relationship between CMV and immune defects, strong and polyfunctional responses are observed in elderly individuals, casting uncertainty on their direct role in age-related immune frailty. In this study, we longitudinally followed a cohort of healthy donors aged over 50 years, assessing their mortality rates and time to death during a 2-year period. Specific T-cell responses to the immunodominant antigen pp65 (IFNγ, TNFα, IL2, MIP1α, CD107a, and perforin production) were analyzed at the beginning of the 2-year observation period. A cytotoxic CD8 pp65-specific T-cell response, without cytokine or chemokine coexpression, was independently associated with all-cause mortality in these elderly individuals. This pp65-specific CD8 T-cell response could be a useful tool to identify individuals with depressed immune function and a higher risk of death.

B cell function and influenza vaccine responses in healthy aging and disease

Influenza vaccination is less effective in elderly as compared to young individuals. Several studies have addressed the identification of immune biomarkers able to monitor or predict a protective humoral immune response to the vaccine. In this review, we summarize these data, with emphasis on the effects of aging on influenza vaccine-specific B cell responses in healthy individuals and patients with Type-2 Diabetes, HIV and cardiovascular diseases.

Childhood environments and cytomegalovirus serostatus and reactivation in adults

Childhood adversity, defined in terms of material hardship or physical or emotional maltreatment has been associated with risk for infection with cytomegalovirus (CMV) among children and adolescents, and with CMV reactivation in children and adults. The present study examined whether different dimensions of childhood experience-those pertaining to socioeconomic status (SES), physical environment, or family relationships-relate differentially to CMV serostatus and reactivation during adulthood. Participants were 140 healthy adults, aged 18-55years (41% female; 64% white). Childhood environments were assessed retrospectively and included family SES (parental housing tenure); childhood neighborhood environment (urban residence; physical conditions; safety; and social atmosphere); residential exposures (parental smoking and physical condition of home); and family relationships (parental divorce; warmth; harmony; dysfunction; parental bonding). Approximately 39% (n=53) of participants were CMV+. In individual analyses controlling for age, sex, race, body mass, current adult SES and smoking status, fewer years of parental home ownership, having a parent who smoked, and living in a poorly maintained or unsafe neighborhood each were associated with greater odds of infection with CMV. By comparison, in individual analyses limited to CMV+ participants, less family warmth, less harmony, greater dysfunction, and suboptimal parental bonding each were related to higher antibody levels, independent of the aforementioned covariates. Findings were not attributable to current adult perceptions of psychological stress or relative levels of emotional stability. These results suggest that different types of childhood adversity may be associated with differential effects on CMV infection and latency.

Inflammatory and myeloid-associated gene expression before and one day after infant vaccination with MVA85A correlates with induction of a T cell response

Background

Tuberculosis (TB) remains a global health problem, with vaccination likely to be a necessary part of a successful control strategy. Results of the first Phase 2b efficacy trial of a candidate vaccine, MVA85A, evaluated in BCG-vaccinated infants were published last year. Although no improvement in efficacy above BCG alone was seen, cryopreserved samples from this trial provide an opportunity to study the immune response to vaccination in this population.

Methods

We investigated blood samples taken before vaccination (baseline) and one and 28 days post-vaccination with MVA85A or placebo (Candin). The IFN-γ ELISpot assay was performed at baseline and on day 28 to quantify the adaptive response to Ag85A peptides. Gene expression analysis was performed at all three timepoints to identify early gene signatures predictive of the magnitude of the subsequent adaptive T cell response using the significance analysis of microarrays (SAM) statistical package and gene set enrichment analysis.

Results

One day post-MVA85A, there is an induction of inflammatory pathways compared to placebo samples. Modules associated with myeloid cells and inflammation pre- and one day post-MVA85A correlate with a higher IFN-γ ELISpot response post-vaccination. By contrast, previous work done in UK adults shows early inflammation in this population is not associated with a strong T cell response but that induction of regulatory pathways inversely correlates with the magnitude of the T cell response. This may be indicative of important mechanistic differences in how T cell responses develop in these two populations following vaccination with MVA85A.

Conclusion

The results suggest the capacity of MVA85A to induce a strong innate response is key to the initiation of an adaptive immune response in South African infants but induction of regulatory pathways may be more important in UK adults. Understanding differences in immune response to vaccination between populations is likely to be an important aspect of developing successful vaccines and vaccination strategies.

Trial registration

ClinicalTrials.gov number NCT00953927

Better immunity in later life: a position paper

Ageing is the greatest challenge that health-care systems will have to deal with this century. This is because a wide spectrum of pathological impairments emerge in the later part of the human life course which sharply increase mortality and reduce quality of life. Dysfunction of the immune system with advancing age is of crucial importance to the development of disability in later life and finally death. Understanding immune ageing, immunosenescence, has long been recognised as an essential prerequisite for the delivery of effective interventions which will improve late life health. Ten years ago, the ImAginE consortium undertook a broad ranging series of projects which added significantly to our understanding of how fundamental ageing mechanisms drove immune decline. In the decade which followed, abundant evidence has accumulated from nonhuman model systems that ageing results from the progressive operation of a relatively few common processes which act across the major organ systems. These advances in fundamental understanding both allow better clarification of the potential cross-system dysregulation that occurs in ageing and open new avenues for intervention. Over the course of a 2-day workshop, the original ImAginE participants have considered these issues and present some suggestions for current priority areas in immunosenescence.

Consistent associations between measures of psychological stress and CMV antibody levels in a large occupational sample

Cytomegalovirus (CMV) is a herpes virus that has been implicated in biological aging and impaired health. Evidence, largely accrued from small-scale studies involving select populations, suggests that stress may promote non-clinical reactivation of this virus. However, absent is evidence from larger studies, which allow better statistical adjustment for confounding and mediating factors, in more representative samples. The present study involved a large occupational cohort (N=887, mean age=44, 88% male). Questionnaires assessed psychological (i.e., depression, anxiety, vital exhaustion, SF-12 mental health), demographic, socioeconomic (SES), and lifestyle variables. Plasma samples were analyzed for both the presence and level of CMV-specific IgG antibodies (CMV-IgG), used as markers for infection status and viral reactivation, respectively. Also assessed were potential biological mediators of stress-induced reactivation, such as inflammation (C-reactive protein) and HPA function (awakening and diurnal cortisol). Predictors of CMV infection and CMV-IgG among the infected individuals were analyzed using logistic and linear regression analyses, respectively. Confirming prior reports, lower SES (education and job status) was positively associated with infection status. Among those infected (N=329), higher CMV-IgG were associated with increased anxiety (β=.14, p<.05), depression (β=.11, p=.06), vital exhaustion (β=.14, p<.05), and decreased SF-12 mental health (β=-.14, p<.05), adjusting for a range of potential confounders. Exploratory analyses showed that these associations were generally stronger in low SES individuals. We found no evidence that elevated inflammation or HPA-function mediated any of the associations. In the largest study to date, we established associations between CMV-IgG levels and multiple indicators of psychological stress. These results demonstrate the robustness of prior findings, and extend these to a general working population. We propose that stress-induced CMV replication warrants further research as a psychobiological mechanism linking stress, aging and health.

Tailored vaccines targeting the elderly using whole inactivated influenza vaccines bearing cytokine immunomodulators

Influenza and its complications disproportionately affect the elderly, leading to high morbidity and mortality in this ever-increasing population. Despite widespread vaccination efforts, the current influenza vaccines are less effective in the elderly; hence newer vaccine strategies are needed to improve their efficacy in this age group. We have previously shown that co-presentation of cytokines on the surface of inactivated influenza virus particles affords better protection from lethal homotypic viral challenge in young adult mice than conventional non-adjuvanted whole inactivated vaccine. Here, we determined the efficacy of these vaccine formulations in Balb/c mice "aged" to 17 months ("aged mice") along with the addition of a membrane-bound interleukin-12 (IL-12) vaccine formulation. Our investigations found that a single low-dose intramuscular vaccination with inactivated whole influenza vaccine co-presenting IL-12 was sufficient to provide enhanced protection from subsequent influenza challenge as compared with non-adjuvanted whole inactivated vaccine. Our results indicate that incorporation of cytokines such as IL-12 in a membrane-bound formulation in whole inactivated vaccine may provide a means to lower the vaccine dose while eliciting enhanced protective responses in the elderly, an age group that responds poorly to current vaccination regimens.

Nutrition, diet and immunosenescence

Ageing is characterized by immunosenescence and the progressive decline in immunity in association with an increased frequency of infections and chronic disease. This complex process affects both the innate and adaptive immune systems with a progressive decline in most immune cell populations and defects in activation resulting in loss of function. Although host genetics and environmental factors, such as stress, exercise and diet can impact on the onset or course of immunosenescence, the mechanisms involved are largely unknown. This review focusses on identifying the most significant aspects of immunosenescence and on the evidence that nutritional intervention might delay this process, and consequently improve the quality of life of the elderly.

Ageing, immunity and influenza: a role for probiotics?

Influenza is a major cause of death in the over 65s. Increased susceptibility to infection and reduced response to vaccination are due to immunosenscence in combination with medical history and lifestyle factors. Age-related alterations in the composition of the gut microbiota have a direct impact on the immune system and it is proposed that modulation of the gut microbiota using pre- and probiotics could offer an opportunity to improve immune responses to infections and vaccination in older people. There is growing evidence that probiotics have immunomodulatory properties, which to some extent are strain-dependent, and are strongly influenced by ageing. Randomised controlled trials suggest that probiotics may reduce the incidence and/or severity of respiratory infections, although there is limited data on older people. A small number of studies have examined the potential adjuvant effects of selected probiotics for vaccination against influenza; however, the data is inconsistent, particularly in older people. This review describes the impact of age-related changes in the gut on the immune response to respiratory infections and evaluates whether restoration of gut microbial homoeostasis by probiotics offers an opportunity to modulate the outcome of respiratory infections and vaccination against influenza in older people. Although there is promising evidence for effects of probiotics on human health, there is a lack of consistent data, perhaps partly due to strain-specific differences and an influence of the age of the host. Further research is critical in evaluating the potential use of probiotics in respiratory infections and vaccination in the ageing population.

Immunosenescence, aging, and systemic lupus erythematous

Senescence is a normal biological process that occurs in all organisms and involves a decline in cell functions. This process is caused by molecular regulatory machinery alterations, and it is closely related to telomere erosion in chromosomes. In the context of the immune system, this phenomenon is known as immunosenescence and refers to the immune function deregulation. Therefore, functions of several cells involved in the innate and adaptive immune responses are severely compromised with age progression (e.g., changes in lymphocyte subsets, decreased proliferative responses, chronic inflammatory states, etc.). These alterations make elderly individuals prone to not only infectious diseases but also to malignancy and autoimmunity. This review will explore the molecular aspects of processes related to cell aging, their importance in the context of the immune system, and their participation in elderly SLE patients.

The effect of age on thymic function

Age-related regression of the thymus is associated with a decline in naïve T cell output. This is thought to contribute to the reduction in T cell diversity seen in older individuals and linked with increased susceptibility to infection, autoimmune disease, and cancer. Thymic involution is one of the most dramatic and ubiquitous changes seen in the aging immune system, but the mechanisms which underlying this process are poorly understood. However, a picture is emerging, implicating the involvement of both extrinsic and intrinsic factors. In this review we assess the role of the thymic microenvironment as a potential target that regulates thymic involution, question whether thymocyte development in the aged thymus is functionally impaired, and explore the kinetics of thymic involution.

A novel B cell population revealed by a CD38/CD24 gating strategy: CD38(-)CD24 (-) B cells in centenarian offspring and elderly people

The B cell arm of adaptive immunity undergoes significant modifications with age. Elderly people are characterized by impaired B cell responses reflected in a reduced ability to effectively respond against viruses and bacteria. Alterations of immunity with advancing age (immunosenescence) have been widely studied in centenarians who are considered a good example of successful aging. In recent years, attention has shifted to centenarian offspring (CO) as a model of people genetically advantaged for healthy aging and longevity. Here, we describe the preliminary characterization of a proposed new population of memory B cells, defined as CD19(+)CD38(-)CD24(-), which we find at higher frequencies in the elderly but less so in CO than healthy age-matched random controls. In addition, we found a decreased expression of RP105 (CD180), a toll-like receptor-associated molecule, on these cells. CD180 downregulation may potentially be a marker of immunosenescence. Moreover, we show that these CD19(+)CD38(-)CD24(-) B cells produce TNF and hypothesize that their observed expansion in the elderly might contribute to the increased inflammatory status sometimes designated "inflamm-aging."

Long-term immunogenicity of an AS03-adjuvanted influenza A(H1N1)pdm09 vaccine in young and elderly adults: an observer-blind, randomized trial

BACKGROUND

This study (NCT00979602) evaluated the immunogenicity and relative protective efficacy of one dose of influenza A(H1N1)pdm09 vaccine with or without AS03 (an α-tocopherol oil-in-water emulsion based Adjuvant System).

METHODS

Four thousands and forty-eight healthy adults aged ≥ 18 years were randomized (1:1) to receive one dose of either the adjuvanted split virion (3.75 μg hemagglutinin antigen [HA]/AS03) or non-adjuvanted (15 μg HA) vaccine. Hemagglutination inhibition [HI] antibody response was evaluated before vaccination and at Days 21, 42 and 182 (Month 6). Safety of the study vaccines was evaluated during the entire study duration.

RESULTS

At Day 21, both study vaccines induced HI immune responses meeting the US regulatory criteria in subjects 18-64 years (seroprotection rate [SPR]: 98.0% [97.1-98.6]; seroconversion rate [SCR]: 89.7% [88.0-91.2] in the AS03-adjuvanted group; SPR: 91.4% [89.9-92.8]; SCR: 74.6% [72.3-76.9] in the non-adjuvanted group) and >64 years of age (SPR: 86.0% [82.5-89.0]; SCR: 75.3% [71.1-79.2] in the AS03-adjuvanted group; SPR: 69.1% [64.6-73.3]; SCR: 56.7% [52.0-61.3] in the non-adjuvanted group). The AS03-adjuvanted vaccine induced higher HI geometric mean titers than the non-adjuvanted vaccine at all time points. At Month 6, only subjects 18-64 years of age from both vaccine groups still met the US regulatory criteria (SPR: 82.1% [80.0-84.1]; SCR: 62.3% [59.6-64.8] in the AS03-adjuvanted group; SPR: 75.3% [72.9-77.5]; SCR: 53.7% [51.0-56.4] in the non-adjuvanted group). Protective efficacy was not evaluated due to low number of RT-qPCR-confirmed A(H1N1)pdm09 influenza cases. Through Month 12, 216 serious adverse events (in 157 subjects: 84 in the AS03-adjuvanted and 73 in the non-adjuvanted group) and 12 potentially immune mediated diseases (5 in the AS03-adjuvanted and 7 in the non-adjuvanted group) were reported.

CONCLUSION

A single dose of either adjuvanted or non-adjuvanted influenza A(H1N1)pdm09 vaccine induced protective HI antibody levels against the A/California/7/2009 strain that persisted through Month 6 in the 18-64 years population.

Human T cell aging and the impact of persistent viral infections

Aging is associated with a dysregulation of the immune response, loosely termed “immunosenescence.” Each part of the immune system is influenced to some extent by the aging process. However, adaptive immunity seems more extensively affected and among all participating cells it is the T cells that are most altered. There is a large body of experimental work devoted to the investigation of age-associated differences in T cell phenotypes and functions in young and old individuals, but few longitudinal studies in humans actually delineating changes at the level of the individual. In most studies, the number and proportion of late-differentiated T cells, especially CD8+ T cells, is reported to be higher in the elderly than in the young. Limited longitudinal studies suggest that accumulation of these cells is a dynamic process and does indeed represent an age-associated change. Accumulations of such late-stage cells may contribute to the enhanced systemic pro-inflammatory milieu commonly seen in older people. We do not know exactly what causes these observed changes, but an understanding of the possible causes is now beginning to emerge. A favored hypothesis is that these events are at least partly due to the effects of the maintenance of essential immune surveillance against persistent viral infections, notably Cytomegalovirus (CMV), which may exhaust the immune system over time. It is still a matter of debate as to whether these changes are compensatory and beneficial or pathological and detrimental to the proper functioning of the immune system and whether they impact longevity. Here, we will review present knowledge of T cell changes with aging and their relation to chronic viral and possibly other persistent infections.

Dose response kinetics of CD8 lymphocytes from young animals transfused into old animals and challenged with influenza

Transfusion of autologous leukocytes after prolonged storage has been proposed as a means of rejuvenating the immune system of older individuals. The rationale for this approach is that age related immune decline is associated with a diminished pool of naïve T cells following atrophy of the thymus and reduction in thymic output. The presence of high levels of naïve T cells within the blood of young individuals could provide a boost to the immune system of an older “self” through a rejuvenation of the naïve T cell pool. However what remains unresolved is whether the cells could be incorporated effectively into the T cell pool of the host and whether effectors could be generated. Using CD45 congenic mice in our experiments we show that the transfusion of young donor cells into older congenic host animals leads to their successful incorporation into the peripheral T cell pool. When the recipients were challenged with influenza virus, specific effector CD8 cells were generated which were of both host and donor origin. We found no relationship between the number of responder cells of donor origin at the time of assay and the number of cells injected.

An empirical approach towards the efficient and optimal production of influenza-neutralizing ovine polyclonal antibodies demonstrates that the novel adjuvant CoVaccine HT™ is functionally superior to Freund's adjuvant

Passive immunotherapies utilising polyclonal antibodies could have a valuable role in preventing and treating infectious diseases such as influenza, particularly in pandemic situations but also in immunocompromised populations such as the elderly, the chronically immunosuppressed, pregnant women, infants and those with chronic diseases. The aim of this study was to optimise current methods used to generate ovine polyclonal antibodies. Polyclonal antibodies to baculovirus-expressed recombinant influenza haemagglutinin from A/Puerto Rico/8/1934 H1N1 (PR8) were elicited in sheep using various immunisation regimens designed to investigate the priming immunisation route, adjuvant formulation, sheep age, and antigen dose, and to empirically ascertain which combination maximised antibody output. The novel adjuvant CoVaccine HT™ was compared to Freund’s adjuvant which is currently the adjuvant of choice for commercial production of ovine polyclonal Fab therapies. CoVaccine HT™ induced significantly higher titres of functional ovine anti-haemagglutinin IgG than Freund’s adjuvant but with fewer side effects, including reduced site reactions. Polyclonal hyperimmune sheep sera effectively neutralised influenza virus in vitro and, when given before or after influenza virus challenge, prevented the death of infected mice. Neither the age of the sheep nor the route of antigen administration appeared to influence antibody titre. Moreover, reducing the administrated dose of haemagglutinin antigen minimally affected antibody titre. Together, these results suggest a cost effective way of producing high and sustained yields of functional ovine polyclonal antibodies specifically for the prevention and treatment of globally significant diseases.