Mechanisms for decreased function of B cells in aged mice and humans

Immunogenicity and safety of quadrivalent influenza vaccine among young and older adults in Tianjin, China: implication of immunosenescence as a risk factor

BACKGROUND

Older adults are more vulnerable to seasonal influenza than younger adults. The immune responses of older persons to the influenza vaccine are usually poorer than those of young individuals, which is hypothesized due to immunosenescence. We conducted a study to evaluate the immunogenicity and safety of a quadrivalent inactivated influenza vaccine (IIV4) in a total of 167 young (< 65 years, n = 79) and older (≥ 65 years, n = 88) adults from October 2021 to March 2022 in Tianjin, China. A single dose was administered to all participants. Blood samples were collected and strain-specific hemagglutination inhibition (HAI) antibody titers were measured before and 21 to 28 days after vaccination. Safety information was also collected for 28 days and 6 months after vaccination. Differences in immunogenicity and safety were compared between young and old age groups, and multivariate logistic regression was used to estimate the effect of age and other factors on HAI antibody responses.

RESULTS

Overall, geometric mean titers (GMTs) against all four vaccine strains in older adults were lower than those in the young, whereas the seroconversion rates (SCRs) were similar. Multivariate logistic regression analysis showed that age, influenza vaccination history, and pre-vaccination HAI titers were independent factors affecting SCRs and seroprotection rates (SCRs). Older age had significant negative impact on SCRs against H1N1 (OR, 0.971; 95% CI: 0.944-0.999; P = 0.042) and B/Victoria (OR, 0.964; 95% CI: 0.937-0.992; P = 0.011). In addition, there was a significant negative correlation between chronological age (years) and post-vaccination HAI titers against H1N1 (rho = -0.2298, P < 0.0001), B/Victoria (rho = -0.2235, P = 0.0037), and B/Yamagata (rho = -0.3689, P < 0.0001). All adverse events were mild (grade 1 or grade 2) that occurred within 28 days after vaccination, and no serious adverse event was observed.

CONCLUSIONS

IIV4 is immunogenic and well-tolerated in young and older adults living in Tianjin, China. Our findings also indicate that age is an independent factor associated with poorer humoral immune responses to IIV4.

Single-cell transcriptomics of peripheral blood in the aging mouse

Compositional and transcriptional changes in the hematopoietic system have been used as biomarkers of immunosenescence and aging. Here, we use single-cell RNA-sequencing to study the aging peripheral blood in mice and characterize the changes in cell-type composition and transcriptional profiles associated with age. We identified 17 clusters from a total of 14,588 single cells. We detected a general upregulation of antigen processing and presentation and chemokine signaling pathways and a downregulation of genes involved in ribosome pathways with age. In old peripheral blood, we also observed an increased percentage of cells expressing senescence markers (Cdkn1a, and Cdkn2a). In addition, we detected a cluster of activated T cells exclusively found in old blood, with lower expression of Cd28 and higher expression of Bcl2 and Cdkn2a, suggesting that the cells are senescent and resistant to apoptosis.

Primary immune responses are negatively impacted by persistent herpesvirus infections in older people: results from an observational study on healthy subjects and a vaccination trial on subjects aged more than 70 years old

Background

Advanced age is accompanied by a decline of immune functions, which may play a role in increased vulnerability to emerging pathogens and low efficacy of primary vaccinations in elderly people. The capacity to mount immune responses against new antigens is particularly affected in this population. However, its precise determinants are not fully understood. We aimed here at establishing the influence of persistent viral infections on the naive T-cell compartment and primary immune responsiveness in older adults.

Methods

We assessed immunological parameters, related to CD8⁺ and CD4⁺ T-cell responsiveness, according to the serological status for common latent herpesviruses in two independent cohorts: 1) healthy individuals aged 19y to 95y (n = 150) and 2) individuals above 70y old enrolled in a primo-vaccination clinical trial (n = 137).

Findings

We demonstrate a prevalent effect of age and CMV infection on CD8⁺ and CD4⁺ naive T cells, respectively. CMV seropositivity was associated with blunted CD4⁺ T-cell and antibody responses to primary vaccination.

Interpretation

These data provide insights on the changes in adaptive immunity over time and the associated decline in vaccine efficacy with ageing. This knowledge is important for the management of emerging infectious diseases in elderly populations.

Marrow failure and aging: The role of "Inflammaging"

Despite aging and the enormous cellular output required of the marrow every day of the lifespan, most aged patients do not suffer significant marrow failure or cytopenias, an attestation to the proliferative capacity of this system. However, as marrow and its hematopoietic stem cells age, a reduction in ability to maintain homeostasis after stress or with exposure to prolonged chronic inflammation, so-called "inflammaging," may contribute to cytopenias, inadequate immune responses, and dysplasia/leukemia. In some instances, these changes may be intrinsic to the stem cell but in others, there may be extrinsic environmental influences. In this review, the role of aging as it relates to stem cell changes, immune function, and anemia are reviewed.

Extreme disruption of heterochromatin is required for accelerated hematopoietic aging

Loss of heterochromatin has been proposed as a universal mechanism of aging across different species and cell types. However, a comprehensive analysis of hematopoietic changes caused by heterochromatin loss is lacking. Moreover, there is conflict in the literature around the role of the major heterochromatic histone methyltransferase Suv39h1 in the aging process. Here, we use individual and dual deletion of Suv39h1 and Suv39h2 enzymes to examine the causal role of heterochromatin loss in hematopoietic cell development. Loss of neither Suv39h1 nor Suv39h2 individually had any effect on hematopoietic stem cell function or the development of mature lymphoid or myeloid lineages. However, deletion of both enzymes resulted in characteristic changes associated with aging such as reduced hematopoietic stem cell function, thymic involution and decreased lymphoid output with a skewing toward myeloid development, and increased memory T cells at the expense of naive T cells. These cellular changes were accompanied by molecular changes consistent with aging, including alterations in nuclear shape and increased nucleolar size. Together, our results indicate that the hematopoietic system has a remarkable tolerance for major disruptions in chromatin structure and reveal a role for Suv39h2 in depositing sufficient H3K9me3 to protect the entire hematopoietic system from changes associated with premature aging.

Overcoming immune dysfunction in the elderly: trained immunity as a novel approach

People with advanced age have a higher susceptibility to infections and exhibit increased mortality and morbidity as the ability of the immune system to combat infections decreases with age. While innate immune cells display functional defects such as decreased phagocytosis, chemotaxis and cytokine production, adaptive immune cells exhibit reduced receptor diversity, defective antibody production and a sharp decline in naive cell populations. Successful responses to vaccination in the elderly are critical to prevent common infections such as influenza and pneumonia, but vaccine efficacy decreases in older individuals compared with young adults. Trained immunity is a newly emerging concept that showed that innate immune cells possess non-specific immunological memory established through epigenetic and metabolic reprogramming upon encountering certain pathogenic stimuli. Clinical studies suggest that trained immunity can be utilized to enhance immune responses against infections and improve the efficiency of vaccinations in adults; however, how trained immunity responses are shaped with advanced age is still an open question. In this review, we provide an overview of the age-related changes in the immune system with a focus on innate immunity, discuss current vaccination strategies for the elderly, present the concept of trained immunity and propose it as a novel approach to enhance responses against infections and vaccinations in the elderly population.

Understanding immunosenescence and its impact on vaccination of older adults

Older adults are more susceptible to viral and bacterial infection, and experience higher incidence and severity of infectious diseases. Although vaccination is the most logical solution in preventing infectious diseases, primary vaccine responses in individuals aged ≥65 years-old fail to generate complete protection. This is presumably attributed to immunosenescence, a term that describes functional differences associated with the immune system and natural age advancement. Both the innate and adaptive immune systems experience age-related impairments that contribute to insufficient protection following vaccination. This review addresses current knowledge of age-related changes that affect vaccine responsiveness; including the deficits in innate cell functions, dampened humoral and cell-mediated immune responses, current vaccination schedules for older adults, and concludes with potential strategies for improving vaccine efficacy specifically for this age group. Due to an age-related decline in immunity and poor vaccine responses, infectious diseases remain a burden among the aged population.

Dysfunction of B Cell Leading to Failure of Immunoglobulin Response Is Ameliorated by Dietary Silk Peptide in 14-Month-Old C57BL/6 Mice

Anti-aging research suggests that immunosenescent cells can play deleterious roles in the immune system. Here, young (2 months old) and old (14 months old) C57BL/6 mice received a daily oral dose (100 or 750 mg/kg/day) of acid-hydrolyzed silk peptide (SP) for a period of 5 weeks. Mouse spleen, lymph node, and serum were analyzed to determine the immune homeostasis of SP by flow cytometry, Western blotting, ELISA, and qRT-PCR. The results suggest that SP ameliorates age-related dysfunction of T and B cells. Amelioration of B cell dysfunction improved the immunoglobulin response in aged mice. Taken together, the results suggest that SP restores immune homeostasis with respect to immunosenescent cells.

The Interplay between Immunosenescence and Microbiota in the Efficacy of Vaccines

Vaccinations are among the most effective medical procedures and have had an incredible impact on almost everyone’s life. One of the populations that can benefit the most from them are elderly people. Unfortunately, in this group, vaccines are less effective than in other groups, due to immunosenescence. The immune system ages like the whole body and becomes less effective in responding to infections and vaccinations. At the same time, immunosenescence also favors an inflammatory microenvironment, which is linked to many conditions typical of the geriatrics population. The microbiota is one of the key actors in modulating the immune response and, in this review, we discuss the current evidence on the role of microbiota in regulating the immune response to vaccines, particularly in elderly people.

Immunological aging and clinical consequences

Immunosenescence is defined as the changes in the immune system associated with age. It is a progressive and irreversible process involving a decrease in the number of naïve T and B cells, NK cells cytotoxic and activity, and disruption of pro and anti-inflammatory balance by altering the production of IL-2, -4, -6, -10, -10, TNF-α, interferon γ and others. With age there is an increase in autoimmunity and generalized inflammation with simultaneous immunodeficiency, which results in greater susceptibility to infectious diseases, a decrease in reactivity to prophylactic vaccinations, the incidence of autoimmune diseases, and increased risk of infectious injury complications, exacerbation of symptoms of chronic diseases and an insufficient response to the presence of cells cancer. For years, based on the analysis of the frequency of viral and bacterial infections, immunological indicators and inflammation, attempts have been made to develop the immune risk profile (IRP) and effective methods of preventing disorders of the immune system and prolonging the functional capacity of the elderly.

Understanding the Heterogeneous Population of Age-Associated B Cells and Their Contributions to Autoimmunity and Immune Response to Pathogens

In humans and mice, susceptibility to infections and autoimmunity increases with age due to age-associated changes in innate and adaptive immune responses. Aged innate cells are also less active, leading to decreased naive T- and B-cell responses. Aging innate cells contribute to an overall heightened inflammatory environment. Naive T and B cells undergo cell-intrinsic age-related changes that result in reduced effector and memory responses. However, previously established B- and T-cell memory responses persist with age. One dramatic change is the appearance of a newly recognized population of age-associated B cells (ABCs) that has a unique cluster of differentiation (CD)21-CD23- phenotype. Here, we discuss the discovery and origins of the naive phenotype immunoglobulin (Ig)D+ versus activated CD11c+T-bet+ ABCs, with a focus on protective and pathogenic properties. In humans and mice, antigen-experienced CD11c+T-bet+ ABCs increase with autoimmunity and appear in response to bacterial and viral infections. However, our analyses indicate that CD21-CD23- ABCs include a resting, naive, progenitor ABC population that expresses IgD. Similar to generation of CD11c+T-bet+ ABCs, naive ABC response to pathogens depends on toll-like receptor stimulation, making this a key feature of ABC activation. Here, we put forward a potential developmental map of distinct subsets from putative naive ABCs. We suggest that defining signals that can harness the naive ABC response may contribute to protection against pathogens in the elderly. CD11c+T-bet+ ABCs may be useful targets for therapeutic strategies to counter autoimmunity.

Aging and influenza vaccine-induced immunity

Immunosenescence is defined as the progressive deterioration of the immune system with aging. Immunosenescence stifles the generation of protective B and T cell-mediated adaptive immunity in response to various pathogens, resulting in increased disease susceptibility and severity in the elderly population. In particular, immunosenescence has major impacts on the phenotype, function, and receptor repertoire of B and T cells in the elderly, hindering protective responses induced by seasonal influenza virus vaccination. In order to overcome the detrimental impacts of immunosenescence on protective immunity to influenza viruses, we review our current understanding of the effects of aging on adaptive immune responses to influenza and discuss current and future avenues of vaccine research for eliciting more potent anti-influenza immunity in the elderly.

Protein phosphatase 2A as a therapeutic target in inflammation and neurodegeneration

Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric enzyme that catalyzes the selective removal of phosphate groups from protein serine and threonine residues. Emerging evidence suggests that it functions as a tumor suppressor by constraining phosphorylation-dependent signalling pathways that regulate cellular transformation and metastasis. Therefore, PP2A-activating drugs (PADs) are being actively sought and investigated as potential novel anti-cancer treatments. Here we explore the concept that PP2A also constrains inflammatory responses through its inhibitory effects on various signalling pathways, suggesting that PADs may be effective in the treatment of inflammation-mediated pathologies.

B cells from young and old mice switch isotypes with equal frequencies after ex vivo stimulation

To determine whether old B cells have the same capacity to switch isotypes as young cells, we purified splenic follicular, marginal zone, and age-associated B cell subsets from C57BL/6 mice. Cells were stimulated in culture with interleukin 4 and either lipopolysaccharide or anti-CD40, and switching to IgG1 was measured by flow cytometry of surface immunoglobulin. The results show that switching was robust in follicular and marginal zone B cells from old mice and was comparable to their young counterparts. However, age-associated B cells from old mice switched poorly relative to the other subsets. Expression of activation-induced deaminase, which initiates switching, was quantified by qPCR of mRNA, and it was equal between young and old follicular B cells. Thus, in this ex vivo system, the follicular and marginal zone cells from young and old mice behaved similarly, showing that the molecular machinery to perform switching is intact in old B cells.

Immunosenescence: A systems-level overview of immune cell biology and strategies for improving vaccine responses

Immunosenescence contributes to a decreased capacity of the immune system to respond effectively to infections or vaccines in the elderly. The full extent of the biological changes that lead to immunosenescence are unknown, but numerous cell types involved in innate and adaptive immunity exhibit altered phenotypes and function as a result of aging. These manifestations of immunosenescence at the cellular level are mediated by dysregulation at the genetic level, and changes throughout the immune system are, in turn, propagated by numerous cellular interactions. Environmental factors, such as nutrition, also exert significant influence on the immune system during aging. While the mechanisms that govern the onset of immunosenescence are complex, systems biology approaches allow for the identification of individual contributions from each component within the system as a whole. Although there is still much to learn regarding immunosenescence, systems-level studies of vaccine responses have been highly informative and will guide the development of new vaccine candidates, novel adjuvant formulations, and immunotherapeutic drugs to improve vaccine responses among the aging population.

The Confluence of Sex Hormones and Aging on Immunity

The immune systems of post-pubescent males and females differ significantly with profound consequences to health and disease. In many cases, sex-specific differences in the immune responses of young adults are also apparent in aged men and women. Moreover, as in young adults, aged women develop several late-adult onset autoimmune conditions more frequently than do men, while aged men continue to develop many cancers to a greater extent than aged women. However, sex differences in the immune systems of aged individuals have not been extensively investigated and data addressing the effectiveness of vaccinations and immunotherapies in aged men and women are scarce. In this review, we evaluate age- and sex hormone-related changes to innate and adaptive immunity, with consideration about how this impacts age- and sex-associated changes in the incidence and pathogenesis of autoimmunity and cancer as well as the efficacy of vaccination and cancer immunotherapy. We conclude that future preclinical and clinical studies should consider age and sex to better understand the ways in which these characteristics intersect with immune function and the resulting consequences for autoimmunity, cancer, and therapeutic interventions.

Aging, inflammation, immunity and periodontal disease

The increased prevalence and severity of periodontal disease have long been associated with aging, such that this oral condition affects the majority of the adult population over 50 years of age. Although the immune system is a critical component for maintaining health, aging can be characterized by quantitative and qualitative modifications of the immune system. This process, termed 'immunosenescence', is a progressive modification of the immune system that leads to greater susceptibility to infections, neoplasia and autoimmunity, presumably reflecting the prolonged antigenic stimulation and/or stress responses that occur across the lifespan. Interestingly, the global reduction in the host capability to respond effectively to these challenges is coupled with a progressive increase in the general proinflammatory status, termed 'inflammaging'. Consistent with the definition of immunosenescence, it has been suggested that the cumulative effect of prolonged exposure of the periodontium to microbial challenge is, at least in part, a contributor to the effects of aging on these tissues. Thus, it has also been hypothesized that alterations in the function of resident immune and nonimmune cells of the periodontium contribute to the expression of inflammaging in periodontal disease. Although the majority of aging research has focused on the adaptive immune response, it is becoming increasingly clear that the innate immune compartment is also highly affected by aging. Thus, the phenomenon of immunosenescence and inflammaging, expressed as age-associated changes within the periodontium, needs to be more fully understood in this era of precision and personalized medicine and dentistry.

Age-related changes in the transcriptome of antibody-secreting cells

We analyzed age-related defects in B cell populations from young and aged mice. Microarray analysis of bone marrow resident antibody secreting cells (ASCs) showed significant changes upon aging, affecting multiple genes, pathways and functions including those that play a role in immune regulation, humoral immune responses, chromatin structure and assembly, cell metabolism and the endoplasmic reticulum (ER) stress response. Further analysis showed upon aging defects in energy production through glucose catabolism with reduced oxidative phosphorylation. In addition aged B cells had increased levels of reactive oxygen-species (ROS), which was linked to enhanced expression of the co-inhibitor programmed cell death (PD)-1.

Long Noncoding RNAs and RNA-Binding Proteins in Oxidative Stress, Cellular Senescence, and Age-Related Diseases

Cellular senescence is a complex biological process that leads to irreversible cell-cycle arrest. Various extrinsic and intrinsic insults are associated with the onset of cellular senescence and frequently accompany genomic or epigenomic alterations. Cellular senescence is believed to contribute to tumor suppression, immune response, and tissue repair as well as aging and age-related diseases. Long noncoding RNAs (lncRNAs) are >200 nucleotides long, poorly conserved, and transcribed in a manner similar to that of mRNAs. They are tightly regulated during various cellular and physiological processes. Although many lncRNAs and their functional roles are still undescribed, the importance of lncRNAs in a variety of biological processes is widely recognized. RNA-binding proteins (RBPs) have a pivotal role in posttranscriptional regulation as well as in mRNA transport, storage, turnover, and translation. RBPs interact with mRNAs, other RBPs, and noncoding RNAs (ncRNAs) including lncRNAs, and they are involved in the regulation of a broad spectrum of cellular processes. Like other cell fate regulators, lncRNAs and RBPs, separately or cooperatively, are implicated in initiation and maintenance of cellular senescence, aging, and age-related diseases. Here, we review the current understanding of both lncRNAs and RBPs and their association with oxidative stress, senescence, and age-related diseases.

Inflamm-Aging of Hematopoiesis, Hematopoietic Stem Cells, and the Bone Marrow Microenvironment

All hematopoietic and immune cells are continuously generated by hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) through highly organized process of stepwise lineage commitment. In the steady state, HSCs are mostly quiescent, while HPCs are actively proliferating and contributing to daily hematopoiesis. In response to hematopoietic challenges, e.g., life-threatening blood loss, infection, and inflammation, HSCs can be activated to proliferate and engage in blood formation. The HSC activation induced by hematopoietic demand is mediated by direct or indirect sensing mechanisms involving pattern recognition receptors or cytokine/chemokine receptors. In contrast to the hematopoietic challenges with obvious clinical symptoms, how the aging process, which involves low-grade chronic inflammation, impacts hematopoiesis remains undefined. Herein, we summarize recent findings pertaining to functional alternations of hematopoiesis, HSCs, and the bone marrow (BM) microenvironment during the processes of aging and inflammation and highlight some common cellular and molecular changes during the processes that influence hematopoiesis and its cells of origin, HSCs and HPCs, as well as the BM microenvironment. We also discuss how age-dependent alterations of the immune system lead to subclinical inflammatory states and how inflammatory signaling might be involved in hematopoietic aging. Our aim is to present evidence supporting the concept of “Inflamm-Aging,” or inflammation-associated aging of hematopoiesis.

Strong, but Age-Dependent, Protection Elicited by a Deoxyribonucleic Acid/Modified Vaccinia Ankara Simian Immunodeficiency Virus Vaccine

Background.  In this study, we analyzed the protective efficacy of a simian immunodeficiency virus (SIV) macaque 239 (SIVmac239) analogue of the clinically tested GOVX-B11 deoxyribonucleic acid (DNA)/modified vaccinia Ankara (MVA) human immunodeficiency virus vaccine. Methods.  The tested vaccine used a DNA immunogen mutated to mimic the human vaccine and a regimen with DNA deliveries at weeks 0 and 8 and MVA deliveries at weeks 16 and 32. Twelve weekly rectal challenges with 0.3 animal infectious doses of SIV sootey mangabey E660 (SIVsmE660) were administered starting at 6 months after the last immunization. Results.  Over the first 6 rectal exposures to SIVsmE660, <10-year-old tripartite motif-containing protein 5 (TRIM5)α-permissive rhesus macaques showed an 80% reduction in per-exposure risk of infection as opposed to a 46% reduction in animals over 10 years old; and, over the 12 challenges, they showed a 72% as opposed to a 10% reduction. Analyses of elicited immune responses suggested that higher antibody responses in the younger animals had played a role in protection. Conclusions.  The simian analogue of the GOVX-B11 HIV provided strong protection against repeated rectal challenges in young adult macaques.

MicroRNAs (MiRs) Precisely Regulate Immune System Development and Function in Immunosenescence Process

Human aging is a complex process with pivotal changes in gene expression of biological pathways. Immune system dysfunction has been recognized as one of the most important abnormalities induced by senescent names immunosenescence. Emerging evidences suggest miR role in immunosenescence. We aimed to systemically review all relevant reports to clearly state miR effects on immunosenescence process. Sensitive electronic searches carried out. Quality assessment has been performed. Since majority of the included studies were laboratory works, and therefore heterogen, we discussed miR effects on immunological aging process nonstatically. Forty-six articles were found in the initial search. After exclusion of 34 articles, 12 studies enrolled to the final stage. We found that miRs have crucial roles in exact function of immune system. MiRs are involved in the regulation of the aging process in the immune system components and target certain genes, promoting or inhibiting immune system reaction to invasion. Also, miRs control life span of the immune system members by regulation of the genes involved in the apoptosis. Interestingly, we found that immunosenescence is controllable by proper manipulation of the various miRs expression. DNA methylation and histone acetylation have been discovered as novel strategies, altering NF-κB binding ability to the miR promoter sites. Effect of miRs on impairment of immune system function due to the aging is emerging. Although it has been accepted that miRs have determinant roles in the regulation of the immunosenescence; however, most of the reports are concluded from animal/laboratory works, suggesting the necessity of more investigations in human.

B cells in the aging immune system: time to consider B-1 cells

The investigation of immune senescence has uncovered many changes in B cell development, maintenance, and function with increasing age. However, most of these studies have focused on conventional B cell subsets in the spleen. The B-1 cell subset is an essential arm of the innate immune system, which in general has been understudied in terms of immune senescence. Here, we review what is currently known about B cells during aging and go on to describe why B-1 cell biology is an important component of the aging immune system in the context of diseases that most affect the aged population.

Flow cytometric characterizations of leukocyte subpopulations in the peripheral blood of northern pig-tailed macaques (Macaca leonina)

Pig-tailed macaques (Macaca nemistrina group) have been extensively used as non-human primate animal models for various human diseases in recent years, notably for AIDS research due to their sensitivity to HIV-1. Northern pig-tailed macaques (M. leonina) are distributed in China and other surrounding Southeast Asia countries. Although northern pig-tailed macaques have been bred on a large scale as experimental animals since 2012, the reference value of normal levels of leukocytes is not available. To obtain such information, 62 blood samples from male and female healthy northern pig-tailed macaques at different ages were collected. The normal range of major leukocyte subpopulations, such as T lymphocytes, B lymphocytes, natural killer (NK) cells, monocytes, and the expression levels of activation or differentiation related molecules (CD38, HLA-DR, CCR5, CD21, IgD, CD80 and CD86) on lymphocytes were analyzed by flow cytometry. The counts of B cells decreased with age, but those of CD8(+) T cells and NK cells and the frequency of CD38(+)HLA-DR(+)CD4(+) T cells were positively correlated with age. The counts of leukocyte subpopulations were higher in males than those in females except for CD4(+) T cells. Males also showed higher expression levels of IgD and CD21 within B cells. This study provides basic data about the leukocyte subpopulations of northern pig-tailed macaques and compares this species with commonly used Chinese rhesus macaques (M. mulatta), which is meaningful for the biomedical application of northern pig-tailed macaques.

The functional VNTR of IGH enhancer HS1.2 associates with human longevity and interacts with TNFA promoter diplotype in a population of Central Italy

The dysregulation of both immune and inflammatory responses occurring with aging is believed to substantially contribute to morbidity and mortality in humans. We have already reported the association of the functional Variable Number of Tandem Repeat (VNTR) at the Immunoglobulin heavy chain (IGH) enhancer HS1.2 with Immunoglobulin levels and with several autoimmune diseases. Herein we tested the association of the VNTR at the HS1.2 enhancer with human longevity, also evaluating the possible modulatory effect of TNFA promoter diplotype (rs361525/rs1800629). HS1.2 enhancer genotypes have been determined for 193 unrelated healthy individuals from Central Italy divided into two groups: Group 1 (18-84 yrs, mean age 56.8 ± 19.4) and Group 2 (85-100 yrs, mean age 93.0 ± 3.5). Homozygous subjects for 2 allele were significantly disadvantaged in reaching higher life-expectancy (OR=0.457, p=0.021). A significant interaction between TNFA promoter diplotype status, HS1.2 2/2 genotype and the two Groups was found (p=0.014). Of note, TNFA -308A allele seems to exert a protective effect in HS1.2 2/2 carriers. These results support the hypothesis of an important role of HS1.2 VNTR in the puzzle of the immune-system regulation, evidenced also by the potential interaction with TNFA. Moreover, the previous results showing the association of HS1.2 2 allele with inflammatory phenomena are consistent with the hypothesis that this allele is a detrimental factor in reaching advanced age.

Impaired B lymphopoiesis in old age: a role for inflammatory B cells?

Continued generation of new B cells within the bone marrow is required throughout life. However, in old age, B lymphopoiesis is inhibited at multiple developmental stages from hematopoietic stem cells through the late stages of new B cell generation. While changes in B cell precursor subsets, as well as alterations in the supporting bone marrow microenvironment, in old age have been known for the last 20 years, only more recently have insights into the cellular and molecular mechanisms responsible become clarified. Our recent discovery that B cells in aged mice are pro-inflammatory and can diminish B cell generation within the bone marrow suggests a potential mechanism of inappropriate "B cell feedback" which contributes to a bone marrow microenvironment unfavorable to B lymphopoiesis. We hypothesize that the consequences of a pro-inflammatory microenvironment in old age are (1) reduced B cell generation and (2) alteration in the "read-out" of the antibody repertoire. Both of these likely ensue from reduced expression of the surrogate light chain (λ5 + VpreB) and consequently reduced expression of the pre-B cell receptor (preBCR), critical to pre-B cell expansion and Vh selection. In old age, B cell development may progressively be diverted into a preBCR-compromised pathway. These abnormalities in B lymphopoiesis likely contribute to the poor humoral immunity seen in old age.

Immune defects in the risk of infection and response to vaccination in monoclonal gammopathy of undetermined significance and multiple myeloma

The plasma cell proliferative disorders monoclonal gammopathy of undetermined significance (MGUS) and malignant multiple myeloma (MM) are characterized by an accumulation of transformed clonal plasma cells in the bone marrow and production of monoclonal immunoglobulin. They typically affect an older population, with median age of diagnosis of approximately 70 years. In both disorders, there is an increased risk of infection due to the immunosuppressive effects of disease and conjointly of therapy in MM, and response to vaccination to counter infection is compromised. The underlying factors in a weakened immune response in MGUS and MM are as yet not fully understood. A confounding factor is the onset of normal aging, which quantitatively and qualitatively hampers humoral immunity to affect response to infection and vaccination. In this review, we examine the status of immune alterations in MGUS and MM and set these against normal aging immune responses. We focus primarily on quantitative and functional aspects of B-cell immunity. Furthermore, we review the current knowledge relating to susceptibility to infectious disease in MGUS and MM, and how efficacy of conventional vaccination is affected by proliferative disease-related and therapy-related factors.

Stem cell transplantation improves aging-related diseases

Aging is a complex process of damage accumulation, and has been viewed as experimentally and medically intractable. The number of patients with age-associated diseases such as type 2 diabetes mellitus (T2DM), osteoporosis, Alzheimer's disease (AD), Parkinson's disease, atherosclerosis, and cancer has increased recently. Aging-related diseases are related to a deficiency of the immune system, which results from an aged thymus and bone marrow cells. Intra bone marrow-bone marrow transplantation (IBM-BMT) is a useful method to treat intractable diseases. This review summarizes findings that IBM-BMT can improve and treat aging-related diseases, including T2DM, osteoporosis and AD, in animal models.

Preventing or reversing immunosenescence: can exercise be an immunotherapy?

There is now a strong body of evidence demonstrating that aging is accompanied by severe alterations in the immune system, a process known as immunosenescence. Among these changes are alterations in T-cell subpopulation size, cytokine secretion pattern, cell replicative capacity and antibody production, all of which culminate in a proinflammatory state called 'inflammaging' and a diminished capacity to respond to new antigens. These alterations are closely related to the increased mortality and morbidity rates observed in this population. However, the role of exercise on the prevention or treatment of immunosenescence is virtually unknown. Data gathered from the literature regarding the effects of physical activity on immune system aging are still limited and conflicting, with existing reports either advocating benefits or asserting a lack of evidence. Exercise as part of a healthy lifestyle has already been shown to provide long-term benefits with regard to cardiovascular, cognitive, psychosocial and other aspects of the elderly. If positive effects are also observed for immunosenescence, exercise could be a highly cost-effective measure to improve human quality of life compared with other strategies currently being pursued.

CD4 T cell defects in the aged: causes, consequences and strategies to circumvent

Aging leads to reduced immunity, especially adaptive responses. A key deficiency is the poor ability to mount robust antibody response. Although intrinsic alterations in B cells with age are in part responsible, impaired CD4 T cell help makes a major contribution to the poor antibody response. Other CD4 effector responses and memory generation are also impaired. We find delayed and reduced development of CD4 T follicular help (Tfh) cells in aged mice in response to influenza infection with reduction of long-lived plasma cells. When we examine CD4 subsets we also find a shift towards Th1 and cytotoxic CD4 (ThCTL) responses. We summarize strategies to circumvent the CD4 T cell defect in aged, including adjuvants and proinflammatory cytokines. We find that we can strongly enhance responses of aged naïve CD4 T cells by using Toll-like receptor (TLR) activated dendritic cells (DC) as APC in vivo and that this leads to improved germinal center B cells and IgG antibody responses. The enhanced response of aged naïve CD4 T cells is dependent on IL-6 produced by the DC.

Aging affects the proportions of T and B cells in a group of elderly men in a developing country--a pilot study from Pakistan

Immune status is different in the elderly and the young, but whether age-associated differences are similar in developing and industrialized countries is unclear. To approach this question, peripheral blood immune cell phenotypes were analyzed by polychromatic flow cytometry in 50 young and 50 elderly men in a pilot study in a rural area of Pakistan. As a group, the elderly had a significantly lower CD4:CD8 ratio, a lower percentage of CD8+ naïve T cells, and significantly higher percentage of late-differentiated memory cells than the young. No age-associated differences were seen in B cells or NK cells. CD8+ cells as a percentage of CD3+ T cells were positively associated with plasma CRP levels but not other factors. We conclude that there are differences between the peripheral immune cell phenotypes of young and elderly Pakistani men and that these seem broadly similar to those more extensively documented in industrialized countries, despite the marked societal, nutritional, and many other differences in these populations.

Human lymphocyte repertoires in ageing

Deterioration of adaptive immunity with ageing may reflect changes in the repertoire of T cells and B cells available to respond to antigenic challenges, due to altered proportions and absolute numbers of lymphocyte subpopulations as well as changes in the repertoire of antigen receptor genes expressed by these cells. High-throughput DNA sequencing (HTS) now facilitates examination of immunoglobulin and T cell receptor gene rearrangements, and initial studies using these methods to study immune system ageing in humans have demonstrated age-related alterations in the receptor populations within lymphocyte subsets, as well as in repertoires responding to vaccination. Accurate measurement of repertoire diversity remains an experimental challenge. Studies of larger numbers of human subjects, analysis of defined lymphocyte subpopulations including antigen-specific populations, and controlling for factors such as chronic viral infections, will be important for gaining additional understanding of the impact of ageing on human lymphocyte populations.

A comparative review of aging and B cell function in mice and humans

Immune system function declines with age. Here we review and compare age-associated changes in murine and human B cell pools and humoral immune responses. We summarize changes in B cell generation and homeostasis, as well as notable changes at the subcellular level; then discuss how these changes help to explain alterations in immune responses across the adult lifespan of the animal. In each section we compare and contrast findings in the mouse, arguably the best animal model of the aging immune system, with current understanding of B cell immunity in humans.

Differences in alloimmune response between elderly and young mice

OBJECTIVE

The upper age of renal transplant recipients is rising on the transplant wait list. Age-dependent immune responsiveness to new antigens has not been thoroughly studied. This study used a mouse model of alloantibody response to neoalloantigen to study age-related differences.

METHODS

Transgenic huCD20-C57BL/6 mice were immunized intraperitoneally with BALB/c splenocytes (2.5 × 10(7)) at baseline and 1 month. Plasma samples were collected at baseline and 1 and 2 months after inoculation, frozen, and tested in a batch run (n = 22). Samples were tested by flow cytometric crossmatch for alloantibody with 2-fold serial dilution from neat to 1:640 using BALB/c splenocytes as targets. The sum of the median fluorescence intensity of the tested sample was calculated after subtracting that of an autologous serum control. Elderly mice (ELD; 42-103 weeks) at inoculation were compared with younger mice (YOU; 11-15 weeks). Statistical analysis was performed with 2-sample t test.

RESULTS

Mean age (weeks) between the groups was significantly different (ELD 69.3 ± 9.6 vs YOU 13.4 ± 1.4; P < .001). There was no difference in alloantibody between groups at baseline (ELD 0.7 ± 3.1 vs YOU 0.6 ± 0.4; P = .93). There was a higher alloantibody response at 1 month for YOU (52.9 ± 31.78) compared with ELD (5.12 ± 8.18). There was a greater difference after the 2 month (YOU 109.38 ± 66.43 vs ELD 21.97 ± 27.14; P < .0024).

CONCLUSIONS

There was a difference in response to new alloantigen in this animal model. Older animals had significantly decreased responses to new alloantigen stimulation 1 month after inoculation and even more profound decreases at 2 months compared with young animals. This model may be used to study differences in immune refractoriness to antigen signaling. It may be important to adapt clinical immunosuppression in the aged population to possible decreased responses to immune stimulation.

Young and elderly patients with type 2 diabetes have optimal B cell responses to the seasonal influenza vaccine

We evaluated immune response to the seasonal influenza vaccine in young and elderly patients with type 2 diabetes (T2D). Immune measures included the in vivo serum response to the vaccine by hemagglutination inhibition (HAI) and ELISA in 22 patients (14 young, 8 elderly) and 65 healthy age-matched controls (37 young, 28 elderly). B cell-specific biomarkers of optimal vaccine response were measured ex vivo by switched memory B cells and plasmablasts and in vitro by activation-induced cytidine deaminase (AID) in stimulated cells. Markers of systemic and B cell-intrinsic inflammation were also measured. Results show that in vivo responses, as well as B cell-specific markers identified above, decrease by age in healthy individuals but not in T2D patients. This occurred despite high levels of B cell-intrinsic inflammation (TNF-α) in T2D patients, which was surprising as we had previously demonstrated this negatively impacts B cell function. These results altogether suggest that valid protection against influenza can be achieved in T2D patients and proposed mechanisms are discussed.

Causes, consequences, and reversal of immune system aging

The effects of aging on the immune system are manifest at multiple levels that include reduced production of B and T cells in bone marrow and thymus and diminished function of mature lymphocytes in secondary lymphoid tissues. As a result, elderly individuals do not respond to immune challenge as robustly as the young. An important goal of aging research is to define the cellular changes that occur in the immune system and the molecular events that underlie them. Considerable progress has been made in this regard, and this information has provided the rationale for clinical trials to rejuvenate the aging immune system.

Heterovariant cross-reactive B-cell responses induced by the 2009 pandemic influenza virus A subtype H1N1 vaccine

BACKGROUND

The generation of heterovariant immunity is a highly desirable feature of influenza vaccines. The goal of this study was to compare the heterovariant B-cell response induced by the monovalent inactivated 2009 pandemic influenza A virus subtype H1N1 (A[H1N1]pdm09) vaccine with that induced by the 2009 seasonal trivalent influenza vaccine (sTIV) containing a seasonal influenza A virus subtype H1N1 (A[H1N1]) component in young and elderly adults.

METHODS

Plasmablast-derived polyclonal antibodies (PPAb) from young and elderly recipients of A(H1N1)pdm09 vaccine or sTIV were tested for binding activity to various influenza antigens.

RESULTS

In A(H1N1)pdm09 recipients, the PPAb titers against homotypic A(H1N1)pdm09 vaccine were similar to those against the heterovariant seasonal A(H1N1) vaccine and were similar between young and elderly subjects. The PPAb avidity was higher among elderly individuals, compared with young individuals. In contrast, the young sTIV recipients had 10-fold lower heterovariant PPAb titers against the A(H1N1)pdm09 vaccine than against the homotypic seasonal A(H1N1) vaccine. In binding assays with recombinant head and stalk domains of hemagglutinin, PPAb from the A(H1N1)pdm09 recipients but not PPAb from the sTIV recipients bound to the conserved stalk domain.

CONCLUSION

The A(H1N1)pdm09 vaccine induced production of PPAb with heterovariant reactivity, including antibodies targeting the conserved hemagglutinin stalk domain.

Immunosenescence-associated microRNAs in age and heart failure

AIMS

Ageing of the immune system, immunosenescence, is characterized by impaired lymphopoiesis, especially B-lymphocyte maturation, and is a hallmark of chronic heart failure (CHF). MicroRNAs (miRNAs) are non-coding, small RNAs, which post-transcriptionally control gene expression of multiple target genes. The miR-181 family is known to control haematopoietic lineage differentiation. Here, we study the role of the miR-181 family in immunosenescence and CHF.

METHODS AND RESULTS

We conducted a clinical study analysing peripheral blood (PB) for miRNA expression and leucocyte distribution of young healthy controls (25 ± 4 years; n = 30), aged healthy controls (64 ± 5 years; n = 13), and age-matched CHF patients (64 ± 11years; n = 18). The expression of miR-181 family members was reduced, whereas miR-34a was increased in PB of aged individuals. In particular, miR-181c was further reduced in age-matched CHF patients. In PB, we observed reduced numbers of lymphocytes, in particular cytotoxic T cells and B cells, with rising age, and the expression of miR-181 correlated with the number of B cells. Notably, in CHF patients, ischaemic heart failure was associated with a further reduction of total B cells as well as their subpopulations, such as memory B cells, compared with age-matched healthy volunteers.

CONCLUSIONS

Ageing- and CHF-associated changes in PB leucocyte subsets are paralleled by alterations in the expression of miRNAs involved in lymphopoiesis, which might play an important role in the age-related and CHF-mediated dysregulation of immune functions resulting in immunosenescence. Furthermore, miR-181c may serve as a marker for reduced immune functions in CHF patients.

Humoral immune responses are maintained with age in a long-lived ectotherm, the red-eared slider turtle

Aging is typically associated with a decrease in immune function. However, aging does not affect each branch of the immune system equally. Because of these varying effects of age on immune responses, aging could affect taxa differently based on how the particular taxon employs its resources towards different components of immune defense. An example of this is found in the humoral immune system. Specific responses tend to decrease with age while non-specific, natural antibody responses increase with age. Compared with mammals, reptiles of all ages have a slower and less robust humoral immune system. Therefore, they may invest more in non-specific responses and thus avoid the negative consequences of age on the immune system. We examined how the humoral immune system of reptiles is affected by aging and investigated the roles of non-specific, natural antibody responses and specific responses by examining several characteristics of antibodies against lipopolysaccharide (LPS) in the red-eared slider turtle. We found very little evidence of immunosenescence in the humoral immune system of the red-eared slider turtle, Trachemys scripta, which supports the idea that non-specific, natural antibody responses are an important line of defense in reptiles. Overall, this demonstrates that a taxon's immune strategy can influence how the immune system is affected by age.

AID activity in B cells strongly correlates with polyclonal antibody affinity maturation in-vivo following pandemic 2009-H1N1 vaccination in humans

The role of Activation-Induced Cytidine Deaminase (AID) in somatic hypermutation and polyclonal antibody affinity maturation has not been shown for polyclonal responses in humans. We investigated whether AID induction in human B cells following H1N1pdm09 vaccination correlated with in-vivo antibody affinity maturation against hemagglutinin domains in plasma of young and elderly individuals. AID was measured by qPCR in B cells from individuals of different ages immunized with the H1N1pdm09 influenza vaccine. Polyclonal antibody affinity in human plasma for the HA1 and HA2 domains of the H1N1pdm09 hemagglutinin was measured by antibody-antigen complex dissociation rates using real time kinetics in Surface Plasmon Resonance. Results show an age-related decrease in AID induction in B cells following H1N1pdm09 vaccination. Levels of AID mRNA before vaccination and fold-increase of AID mRNA expression after H1N1pdm09 vaccination directly correlated with increase in polyclonal antibody affinity to the HA1 globular domain (but not to the conserved HA2 stalk). In the younger population, significant affinity maturation to the HA1 globular domain was observed, which associated with initial levels of AID and fold-increase in AID after vaccination. In some older individuals (>65 yr), higher affinity to the HA1 domain was observed before vaccination and H1N1pdm09 vaccination resulted in minimal change in antibody affinity, which correlated with low AID induction in this age group. These findings demonstrate for the first time a strong correlation between AID induction and in-vivo antibody affinity maturation in humans. The ability to generate high affinity antibodies could have significant impact on the elucidation of age-specific antibody responses following vaccination and eventual clinical efficacy and disease outcome.

Antibody affinity maturation is a key aspect of an effective immune response to vaccines, likely to have an impact on clinical outcome following exposure to pathogens. Activation-Induced Cytidine Deaminase (AID) in B cells is a key enzyme involved in antibody class switching and somatic hypermutation, required for antibody affinity maturation. This human study demonstrated for the first time that induction of AID following H1N1pdm09 influenza vaccination directly correlated with in-vivo antibody affinity maturation against the hemagglutinin globular domain (HA1), containing most of the protective targets. Importantly, age differences were found. In younger adults, significant affinity maturation to the HA1 globular domain was observed, which associated with higher initial levels of AID and >2-fold-increase in AID after vaccination. With increased age, a drop in AID activity post-vaccination correlated with lower affinity maturation of the polyclonal antibody responses against the pandemic influenza HA1. However, in a subset of elderly (>65 yr), high affinity antibodies against the HA1 were present prior to vaccination but, in the absence of AID, did not undergo further maturation. Therefore, vaccination of divergent human populations, especially older individuals, should take into consideration their individual AID status and the history of exposure and vaccination against the specific pathogen.

Tristetraprolin: roles in cancer and senescence

Cancer and senescence are both complex transformative processes that dramatically alter many features of cell physiology and their interactions with surrounding tissues. Developing the wide range of cellular features characteristic of these conditions requires profound alterations in global gene expression patterns, which can be achieved by suppressing, activating, or uncoupling cellular gene regulatory pathways. Many genes associated with the initiation and development of tumors are regulated at the level of mRNA decay, frequently through the activity of AU-rich mRNA-destabilizing elements (AREs) located in their 3'-untranslated regions. As such, cellular factors that recognize and control the decay of ARE-containing mRNAs can influence tumorigenic or senescent phenotypes mediated by products of these transcripts. In this review, we discuss evidence showing how suppressed expression and/or activity of the ARE-binding protein tristetraprolin (TTP) can contribute to these processes. Next, we outline current findings linking TTP suppression to exacerbation of individual tumorigenic phenotypes, and the roles of specific TTP substrate mRNAs in mediating these effects. Finally, we survey potential mechanisms that cells may employ to suppress TTP expression in cancer, and propose potential diagnostic and therapeutic strategies that may exploit the relationship between TTP expression and tumor progression or senescence.

β-Diketone modified trastuzumab: a next-generation of Herceptin for resistant breast cancer cells?

Despite the initial efficacy of trastuzumab (commercially named Herceptin), acquired resistance in a majority of patients remains the biggest hurdle in breast cancer therapy. Recently, the Scripps Research Institute developed a method termed "instant immunity", in which antibodies (chemical programmed antibody) are rapidly induced by chemicals like β-diketone. When β-diketone is chemically linked to peptides specifically targeting cancer cells, the instant chemical programmed antibody would clear the cancer cells through antibody-dependent cellular cytotoxicity (ADCC) and complement-directed cytotoxicity (CDC). This novel strategy has a super advantage over passive immunization or immunization with recombinant or vectored vaccines because it induces a universal immune response and memory. Theoretically, combination of the cancer cell specific recognition advantage of trastuzumab and cancerous cell clearance of active immunization would be an option for trastuzumab resistant patients, which harbors both the advantages of cancer specific targeting of trastuzumab and active immunization of the "instant immunity", implicating a better clinical outcome. Further studies are needed to verify our hypothesis, which is worth validating.

HI responses induced by seasonal influenza vaccination are associated with clinical protection and with seroprotection against non-homologous strains

Vaccination against influenza induces homologous as well as cross-specific hemagglutination inhibiting (HI) responses. Induction of cross-specific HI responses may be essential when the influenza strain does not match the vaccine strain, or even to confer a basic immune response against a pandemic influenza virus. We carried out a clinical study to evaluate the immunological responses after seasonal vaccination in healthy adults 18-60 years of age, receiving the yearly voluntary vaccination during the influenza season 2006/2007. Vaccinees of different age groups were followed for laboratory confirmed influenza (LCI) and homologous HI responses as well as cross-specific HI responses against the seasonal H1N1 strain of 2008 and pandemic H1N1 virus of 2009 (H1N1pdm09) were determined. Homologous HI titers that are generally associated with protection (i.e. seroprotective HI titers ≥40) were found in more than 70% of vaccinees. In contrast, low HI titers before and after vaccination were significantly associated with seasonal LCI. Cross-specific HI titers ≥40 against drifted seasonal H1N1 were found in 69% of vaccinees. Cross-specific HI titers ≥40 against H1N1pdm09 were also significantly induced, especially in the youngest age group. More specifically, cross-specific HI titers ≥40 against H1N1pdm09 were inversely correlated with age. We did not find a correlation between the subtype of influenza which was circulating at the age of birth of the vaccinees and cross-specific HI response against H1N1pdm09. These data indicate that the HI titers before and after vaccination determine the vaccination efficacy. In addition, in healthy adults between 18 and 60 years of age, young adults appear to be best able to mount a cross-protective HI response against H1N1pdm09 or drifted seasonal influenza after seasonal vaccination.

Phenotype and functions of conventional dendritic cells are not compromised in aged mice

Aging has profound effects on the immune system, including thymic involution, reduced diversity of the T cell receptor repertoire, reduced effector T cell and B cell function and chronic increase of proinflammatory cytokine production by innate immune cells. The precise effects of aging on conventional dendritic cells (cDC), the main antigen presenting cells of the immune system, however, are not well understood. We found that in aged mice the number of cDC in the spleen and lymph nodes remained stable, whereas the number of cDC in the lungs increased with age. Whereas cDC in mice showed similar cycling kinetics in all organs tested, cDC reconstitution by aged bone marrow precursors was relatively higher than that of their young counterparts. With the exception of CD86, young and aged cDC did not differ in their expression of co-stimulatory molecules at steady state. Most toll-like receptor (TLR) ligands induced comparable upregulation of co-stimulatory molecules CD40, CD86 and B7H1 on young and aged cDC, whereas TLR2 and TLR5 stimulation resulted in reduced upregulation of CD80 and CD86 on aged cDC in vitro. In vivo, influenza infection-induced upregulation of CD86, but not other co-stimulatory molecules, was lower in aged DC. Young and aged DC were equally capable of direct and cross presentation of antigens in vitro. Transcriptome analysis did not reveal any significant difference between young and aged cDC. These data show that unlike T and B cells, the maintenance of cDC throughout the life of a healthy animal is relatively robust during the aging process.