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

Vaccinomics and adversomics: key elements for a personalized vaccinology

Vaccines are one of the most important and effective tools in the prevention of infectious diseases and research about all the aspects of vaccinology are essential to increase the number of available vaccines more and more safe and effective. Despite the unquestionable value of vaccinations, vaccine hesitancy has spread worldwide compromising the success of vaccinations. Currently, the main purpose of vaccination campaigns is the immunization of whole populations with the same vaccine formulations and schedules for all individuals. A personalized vaccinology approach could improve modern vaccinology counteracting vaccine hesitancy and giving great benefits for human health. This ambitious purpose would be possible by facing and deepening the areas of vaccinomics and adversomics, two innovative areas of study investigating the role of a series of variables able to influence the immune response to vaccinations and the development of serious side effects, respectively. We reviewed the recent scientific knowledge about these innovative sciences focusing on genetic and non-genetic basis involved in the individual response to vaccines in terms of both immune response and side effects.

Development of Respiratory Syncytial Virus Vaccine Candidates for the Elderly

Respiratory syncytial virus (RSV) is a significant threat to elderly populations and repeated infections that occur throughout life are poorly protective. To assess the role of prior RSV infections as well as elderly immune senescence on vaccine efficacy, we compared immune responses after virus-like particle (VLP) immunization of elderly cotton rats and young cotton rats, both previously RSV infected, in order to mimic the human population. We show that immunization of RSV-experienced young or elderly animals resulted in the same levels of anti-pre-F IgG, anti-G IgG, neutralizing antibody titers, and protection from challenge indicating that the delivery of F and G proteins in a VLP is equally effective in activation of protective responses in both elderly and young populations. Our results suggest that F and G protein-containing VLPs induce anti-RSV memory established in prior RSV infections equally well in both young and elderly animals and thus can be an effective vaccine for the elderly.

Preliminary evidence that daily light exposure enhances the antibody response to influenza vaccination in patients with dementia

Enhancing lighting conditions in institutions for individuals with dementia improves their sleep, circadian rhythms and well-being. Here, we report first findings that exposure to brighter light during daytime may support the immune response to the annual influenza vaccination. Eighty older institutionalised patients suffering from dementia (54 women and 26 men) continuously wore an activity tracker for 8 weeks to assess individual light exposure and rest-activity cycles. We analysed the patients’ immune response from two blood samples taken before and 4 weeks after the annual influenza vaccination. Individual antibody concentrations to three influenza virus strains (H3N2, H1N1, IB) were quantified via hemagglutination inhibition assays. By quantifying individual light exposure profiles (including daylight), we classified the patients into a low and a high light exposure group based on a median illuminance of 392.6 lux. The two light exposure groups did not differ in cognitive impairment severity, age or gender distribution. However, patients in the high light exposure group showed a significantly greater circadian rest-activity amplitude (i.e., more daytime activity and less nighttime activity) along with a significantly greater antibody titer increase to the H3N2 vaccine than patients in the low light exposure group, despite similar pre-vaccination concentrations. Sufficient seroprotective responses to all three influenza virus strains were attained for ≥75% of participants. These data provide preliminary evidence for a potentially enhanced immune response in patients with dementia when they received more daily light. Future studies are needed to determine whether regular daily light exposure may have beneficial effects on the human immune system, either directly or via a stabilising circadian sleep-wake rhythms.

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Data from individual light exposures and circadian rest-activity cycles in 80 institutionalised patients with dementia.

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Blood samples were taken before and 4 weeks after the annual influenza vaccination.

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Patients with on average higher light exposure had higher specific antibody titer ratios after the influenza strain H3N2 vaccine.

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Circadian rest-activity amplitude and inter-daily stability were also higher in the group with higher daily light exposures.

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The results provide preliminary evidencefor beneficial effects of light on the immune system in patients with dementia.

DYNAMIC cohort study evaluating metabolic predictors of influenza vaccine immune response in older adults

Immunosenescence (age-related immune dysfunction) and inflamm-aging contribute to suboptimal immune responses in older adults to standard-dose influenza vaccines, which may be exacerbated in those with metabolic co-morbidities. We sought to investigate metabolic factors/predictors of influenza vaccine immune response in an older adult (age ≥65 years) cohort in Singapore, where influenza typically circulates year-round. The primary outcome for the DYNAMIC prospective cohort study was haemagglutination-inhibition titer (HAI) response to each of the trivalent inactivated influenza vaccine strains at day 28 (D28) compared to baseline (D0), as assessed by seroconversion and D28/D0 log2 HAI fold rise. Baseline blood samples were tested for total Vitamin D (25-(OH) D) levels. We enrolled 234 participants in June-Dec 2017. Two hundred twenty completed all study visits. The median age was 71 [IQR 68-75] years, 67 (30.5%) had diabetes mellitus (DM), and the median BMI was 24.9 [IQR 22.2-27.8] kg/m². Median baseline totals 25-(OH) D was 29 [IQR: 21-29] ng/ml. Age, DM, obesity, and baseline 25-(OH) D were not associated with HAI fold rise in multivariable analysis. More recent prior influenza vaccination and higher baseline HAI titers were associated with lower HAI fold rise for influenza A/HK/H3N2. Physical activity was associated with a higher HAI fold rise for influenza A/HK/H3N2 in a dose-response relationship (p-test for trend = 0.015). Older adults with well-controlled metabolic co-morbidities retain HAI response to the influenza vaccine, and physical activity had a beneficial effect on immune response, particularly for influenza A/HK/H3N2.

Declining Prevalence of SARS-CoV-2 Antibodies among Vaccinated Nursing Home Residents and Staff Six Months after the Primary BNT162b2 Vaccination Campaign in Belgium: A Prospective Cohort Study

In the SCOPE study, we monitored SARS-CoV-2 antibodies in a national sample of residents and staff from Belgian nursing homes. Here, we report the seroprevalence among infected and infection-naive residents and staff after the primary COVID-19 vaccination campaign. Among 1554 vaccinated nursing home residents and 1082 vaccinated staff from 69 nursing homes in Belgium, we assessed the proportion having SARS-CoV-2 antibodies approximately two (April 2021), four (June 2021), and six months (August 2021) after a two-dose regimen of the BNT162b2 vaccine. We measured the seroprevalence using SARS-CoV-2 antibody rapid tests and collected socio-demographic and COVID-19 medical data using an online questionnaire. Two months after vaccination (baseline), we found a seroprevalence of 91% (95% CI: 89-93) among vaccinated residents and 99% (95% CI: 98-99) among vaccinated staff. Six months after vaccination, the seroprevalence significantly decreased to 68% (95% CI: 64-72) among residents and to 89% (95% CI; 86-91) among staff (p < 0.001). The seroprevalence was more likely to decrease among infection-naive residents, older residents, or residents with a high care dependency level. These findings emphasize the need for close monitoring of nursing home residents, as a substantial part of this population fails to mount a persistent antibody response after BNT162b2 vaccination.

Nanoparticles reduce monocytes within the lungs to improve outcomes after influenza virus infection in aged mice

Older people exhibit dysregulated innate immunity to respiratory viral infections, including influenza and SARS-CoV-2, and show an increase in morbidity and mortality. Nanoparticles are a potential practical therapeutic that could reduce exaggerated innate immune responses within the lungs during viral infection. However, such therapeutics have not been examined for effectiveness during respiratory viral infection, particular in aged hosts. Here, we employed a lethal model of influenza viral infection in vulnerable aged mice to examine the ability of biodegradable, cargo-free nanoparticles, designated ONP-302, to resolve innate immune dysfunction and improve outcomes during infection. We administered ONP-302 via i.v. injection to aged mice at day 3 after infection, when the hyperinflammatory innate immune response was already established. During infection, we found that ONP-302 treatment reduced the numbers of inflammatory monocytes within the lungs and increased their number in both the liver and spleen, without impacting viral clearance. Importantly, cargo-free nanoparticles reduced lung damage, reduced histological lung inflammation, and improved gas exchange and, ultimately, the clinical outcomes in influenza-infected aged mice. In conclusion, ONP-302 improves outcomes in influenza-infected aged mice. Thus, our study provides information concerning a practical therapeutic, which, if translated clinically, could improve disease outcomes for vulnerable older patients suffering from respiratory viral infections.

Vaccines and Vaccination against SARS-CoV-2: Considerations for the Older Population

Age is among the most prominent risk factors for developing severe COVID-19 disease, and therefore older adults are a major target group for vaccination against SARS-CoV-2. This review focusses on age-associated aspects of COVID-19 vaccines and vaccination strategies, and summarizes data on immunogenicity, efficacy and effectiveness of the four COVID-19 vaccines, which are licensed in the US and/or Europe; namely, the two mRNA vaccines by BioNTech/Pfizer (BNT162b2) and Moderna (mRNA-1273), and the adenovector vaccines developed by AstraZeneca/University Oxford (ChAdOx1-nCoV-19, AZD1222) and Janssen/Johnson&Johnson (Ad26.COV2-S), respectively. After very high protection rates in the first months after vaccination even in the older population, effectiveness of the vaccines, particularly against asymptomatic infection and mild disease, declined at later time points and with the emergence of virus variants. Many high-income countries have recently started administration of additional doses to older adults and other high-risk groups, whereas other parts of the world are still struggling to acquire and distribute vaccines for primary vaccination. Other vaccines are available in other countries and clinical development for more vaccine candidates is ongoing, but a complete overview of COVID-19 vaccine development is beyond the scope of this article.

Predictive factors for vaccine failure to guide vaccination in allogeneic hematopoietic stem cell transplant recipients

Vaccination after hematopoietic stem cell transplantation (HSCT) is essential to protect high-risk patients against potentially lethal infections. Though multiple studies have evaluated vaccine specific responses, no comprehensive analysis of a complete vaccination schedule post-HSCT has been performed and little is known about predictors for vaccine failure. In this context, allogeneic HSCT (alloHSCT) patients were included and vaccinated starting one year post-transplantation. Antibody responses were measured by Multiplex Immuno Assay for pneumococcal (PCV13), meningococcal C, diphtheria, pertussis, tetanus and Haemophilus influenza type b one month after the last vaccination and correlated to clinical and immunological parameters. Vaccine failure was defined as antibody response above vaccine-specific cut-off values for less than four out of six vaccines. Ninety-six patients were included of which 27.1% was found to have vaccine failure. Only 40.6% of all patients responded adequately to all six vaccines. In multivariate analysis, viral reactivation post-HSCT (OR 6.53; P = 0.03), B-cells <135 per mm³ (OR 7.24; P = 0.00) and NK-cells <170 per mm³ (OR 11.06; P = 0.00) were identified as predictors for vaccine failure for vaccination at one year post-alloHSCT. Measurement of antibody responses and an individualized approach for revaccination guided by clinical status and immune reconstitution of B-cells and NK-cells may improve vaccine responses.

Aging and Interferons: Impacts on Inflammation and Viral Disease Outcomes

As highlighted by the COVID-19 global pandemic, elderly individuals comprise the majority of cases of severe viral infection outcomes and death. A combined inability to control viral replication and exacerbated inflammatory immune activation in elderly patients causes irreparable immune-mediated tissue pathology in response to infection. Key to these responses are type I, II, and III interferons (IFNs), which are involved in inducing an antiviral response, as well as controlling and suppressing inflammation and immunopathology. IFNs support monocyte/macrophage-stimulated immune responses that clear infection and promote their immunosuppressive functions that prevent excess inflammation and immune-mediated pathology. The timing and magnitude of IFN responses to infection are critical towards their immunoregulatory functions and ability to prevent immunopathology. Aging is associated with multiple defects in the ability of macrophages and dendritic cells to produce IFNs in response to viral infection, leading to a dysregulation of inflammatory immune responses. Understanding the implications of aging on IFN-regulated inflammation will give critical insights on how to treat and prevent severe infection in vulnerable individuals. In this review, we describe the causes of impaired IFN production in aging, and the evidence to suggest that these impairments impact the regulation of the innate and adaptive immune response to infection, thereby causing disease pathology.

The Complex Role of Regulatory T Cells in Immunity and Aging

The immune system is a tightly regulated network which allows the development of defense mechanisms against foreign antigens and tolerance toward self-antigens. Regulatory T cells (Treg) contribute to immune homeostasis by maintaining unresponsiveness to self-antigens and suppressing exaggerated immune responses. Dysregulation of any of these processes can lead to serious consequences. Classically, Treg cell functions have been described in CD4⁺ T cells, but other immune cells also harbour the capacity to modulate immune responses. Regulatory functions have been described for different CD8⁺ T cell subsets, as well as other T cells such as γδT cells or NKT cells. In this review we describe the diverse populations of Treg cells and their role in different scenarios. Special attention is paid to the aging process, which is characterized by an altered composition of immune cells. Treg cells can contribute to the development of various age-related diseases but they are poorly characterized in aged individuals. The huge diversity of cells that display immune modulatory functions and the lack of universal markers to identify Treg make the expanding field of Treg research complex and challenging. There are still many open questions that need to be answered to solve the enigma of regulatory T cells.

The aging transplant population and immunobiology: any therapeutic implication?

PURPOSE OF REVIEW

The aim of this review is to describe the latest investigations into the immunobiology of aging and the potential impact on outcomes after mechanical circulatory support implantation and heart transplantation. This information is relevant given the growing numbers of older patients with heart failure undergoing evaluation for mechanical circulatory support device (MCSD) or heart transplantation.

RECENT FINDINGS

A host of aging-associated aspects of immune dysfunction have been described in the general population including T-cell senescence, exhaustion, and terminal dedifferentiation, as well as impaired function of innate immune cells. Another important consequence of T-cell senescence is inflammation, which is known to have a strong relationship with both heart failure and frailty in older patients. Recent data on the association between T-cell and monocyte phenotypes as well as evaluation of gene expression and adverse outcomes after MCSD suggests the potential value of immunologic assessment of MCSD and heart transplant candidates and recipients. Measurement of physical frailty represents another avenue for patient evaluation that may complement immunologic assessment. Determination of immune dysfunction and frailty prior to transplantation may have implications for choice of induction and dosing of maintenance immunosuppression.

SUMMARY

As the age of transplant and MCSD candidates and recipients continues to increase, it is important for providers to recognize the potential impact of aging-associated immune dysfunction and how it may influence candidate selection, postintervention monitoring, and adjustment of immunosuppression.

Targeting Inflammation and Immunosenescence to Improve Vaccine Responses in the Elderly

One of the most appreciated consequences of immunosenescence is an impaired response to vaccines with advanced age. While most studies report impaired antibody responses in older adults as a correlate of vaccine efficacy, it is now widely appreciated that this may fail to identify important changes occurring in the immune system with age that may affect vaccine efficacy. The impact of immunosenescence on vaccination goes beyond the defects on antibody responses as T cell-mediated responses are reshaped during aging and certainly affect vaccination. Likewise, age-related changes in the innate immune system may have important consequences on antigen presentation and priming of adaptive immune responses. Importantly, a low-level chronic inflammatory status known as inflammaging has been shown to inhibit immune responses to vaccination and pharmacological strategies aiming at blocking baseline inflammation can be potentially used to boost vaccine responses. Yet current strategies aiming at improving immunogenicity in the elderly have mainly focused on the use of adjuvants to promote local inflammation. More research is needed to understand the role of inflammation in vaccine responses and to reconcile these seemingly paradoxical observations. Alternative approaches to improve vaccine responses in the elderly include the use of higher vaccine doses or alternative routes of vaccination showing only limited benefits. This review will explore novel targets and potential new strategies for enhancing vaccine responses in older adults, including the use of anti-inflammatory drugs and immunomodulators.

Role of Aging and the Immune Response to Respiratory Viral Infections: Potential Implications for COVID-19

Aging impairs immunity to promote diseases, especially respiratory viral infections. The current COVID-19 pandemic, resulting from SARS-CoV-2, induces acute pneumonia, a phenotype that is alarmingly increased with aging. In this article, we review findings of how aging alters immunity to respiratory viral infections to identify age-impacted pathways common to several viral pathogens, permitting us to speculate about potential mechanisms of age-enhanced mortality to COVID-19. Aging generally leads to exaggerated innate immunity, particularly in the form of elevated neutrophil accumulation across murine and large animal studies of influenza infection. COVID-19 patients who succumb exhibit a 2-fold increase in neutrophilia, suggesting that exaggerated innate immunity contributes to age-enhanced mortality to SARS-CoV-2 infection. Further investigation in relevant experimental models will elucidate the mechanisms by which aging impacts respiratory viral infections, including SARS-CoV-2. Such investigation could identify therapies to reduce the suffering of the population at large, but especially among older people, infected with respiratory viruses.

Vaccines to Prevent Infectious Diseases in the Older Population: Immunological Challenges and Future Perspectives

Infectious diseases are a major cause for morbidity and mortality in the older population. Demographic changes will lead to increasing numbers of older persons over the next decades. Prevention of infections becomes increasingly important to ensure healthy aging for the individual, and to alleviate the socio-economic burden for societies. Undoubtedly, vaccines are the most efficient health care measure to prevent infections. Age-associated changes of the immune system are responsible for decreased immunogenicity and clinical efficacy of most currently used vaccines in older age. Efficacy of standard influenza vaccines is only 30-50% in the older population. Several approaches, such as higher antigen dose, use of MF59 as adjuvant and intradermal administration have been implemented in order to specifically target the aged immune system. The use of a 23-valent polysaccharide vaccine against Streptococcus pneumoniae has been amended by a 13-valent conjugated pneumococcal vaccine originally developed for young children several years ago to overcome at least some of the limitations of the T cell-independent polysaccharide antigens, but still is only approximately 50% protective against pneumonia. A live-attenuated vaccine against herpes zoster, which has been available for several years, demonstrated efficacy of 51% against herpes zoster and 67% against post-herpetic neuralgia. Protection was lower in the very old and decreased several years after vaccination. Recently, a recombinant vaccine containing the viral glycoprotein gE and the novel adjuvant AS01B has been licensed. Phase III studies demonstrated efficacy against herpes zoster of approx. 90% even in the oldest age groups after administration of two doses and many countries now recommend the preferential use of this vaccine. There are still many infectious diseases causing substantial morbidity in the older population, for which no vaccines are available so far. Extensive research is ongoing to develop vaccines against novel targets with several vaccine candidates already being clinically tested, which have the potential to substantially reduce health care costs and to save many lives. In addition to the development of novel and improved vaccines, which specifically target the aged immune system, it is also important to improve uptake of the existing vaccines in order to protect the vulnerable, older population.

Influenza vaccination in early Alzheimer's disease rescues amyloidosis and ameliorates cognitive deficits in APP/PS1 mice by inhibiting regulatory T cells

Background

Alzheimer’s disease (AD) is a neurodegenerative disorder strongly correlated with a dysfunctional immune system. Our previous results demonstrated that inactivated influenza vaccine (IIV) facilitates hippocampal neurogenesis and blocks lipopolysaccharide (LPS)-induced cognitive impairment. However, whether IIV improves cognitive deficits in an AD mouse model remains unclear. In addition, early interventions in AD have been encouraged in recent years. Here, we investigated whether IIV immunization at the preclinical stage of AD alters the brain pathology and cognitive deficits in an APP/ PS1 mouse model.

Methods

We assessed spatial learning and memory using Morris water maze (MWM). The brain β-amyloid (Aβ) plaque burden and activated microglia were investigated by immunohistochemistry. Furthermore, flow cytometry was utilized to analyze the proportions of Treg cells in the spleen. A cytokine antibody array was performed to measure the alteration of cytokines in the brain and peripheral immune system.

Results

Five IIV immunizations activated microglia, reduced the Aβ burden and improved the cognitive impairment. Simultaneously, the IIV-induced immune response broke peripheral immunosuppression by reducing Foxp3⁺ regulatory T cell (Treg) activities, whereas the restoration of Treg level in the periphery using all-trans retinoic acid (ATRA) blunted the protective effects of IIV on Aβ burden and cognitive functions. Interestingly, IIV immunization might increase proinflammatory and anti-inflammatory cytokine expression in the brain of APP/PS1 mice, enhanced microglial activation, and enhanced the clustering and phagocytosis of Aβ, thereby creating new homeostasis in the disordered immune microenvironment.

Conclusions

Altogether, our results suggest that early multiple IIV immunizations exert a beneficial immunomodulatory effect in APP/PS1 mice by breaking Treg-mediated systemic immune tolerance, maintaining the activation of microglia and removing of Aβ plaques, eventually improving cognitive deficits.

Decreased ratio of influenza-specific IgG versus IgM in response to influenza vaccination in antiretroviral-treated HIV-infected African Americans compared to Caucasians, and its direct correlation with the percentages of peripheral Tfh cells

BACKGROUND

Racial differences have been observed in the rate of bacterial infection and disease progression in HIV. Here, we evaluate racial differences in seasonal influenza vaccine responses.

METHODS

16 healthy controls (9 Caucasians (CC) and 7 African Americans (AA)) and 26 antiretroviral therapy (ART)-treated aviremic HIV+ subjects (11 CC and 15 AA) were enrolled in the current study. Blood was collected at pre-vaccination (D0) and day 14 (D14) following seasonal influenza vaccination. Serologic responses were characterized in plasma by ELISA. B and T cells were assessed by flow cytometry ex vivo.

RESULTS

The absolute counts of CD4+ CD3+ T cells and CD19+ B cells were similar in healthy controls and HIV-infected individuals, and similar in CC and AA in the two study groups. However, the percentage of peripheral T follicular helper (pTfh) cells was decreased in HIV+ AA compared to HIV+ CC. There were no racial differences in IgG antibody responses against vaccination in the two study groups. However, the ratio of anti-influenza-specific IgG versus IgM induction following vaccination was decreased in HIV+ AA compared to HIV+ CC, which was directly correlated with the percentages of pTfh cells. This racial difference and correlation were not demonstrable in healthy controls.

CONCLUSION

Here we report that HIV + AA has decreased fold induction of IgG versus IgM after influenza vaccination, which may suggest impaired class-switching from IgM to IgG in AA HIV-infected individuals.

Effect of homeostatic T-cell proliferation in the vaccine responsiveness against influenza in elderly people

Background

Seasonal influenza virus infection is a significant cause of morbimortality in the elderly. However, there is poor vaccine efficacy in this population due to immunosenescence. We aimed to explore several homeostatic parameters in the elderly that could impact influenza vaccine responsiveness.

Methods

Subjects (> 60 years old) who were vaccinated against influenza virus were included, and the vaccine response was measured by a haemagglutination inhibition (HAI) test. At baseline, peripheral CD4 and CD8 T-cells were phenotypically characterized. Thymic function and the levels of different inflammation-related biomarkers, including Lipopolysaccharide Binding Protein (LBP) and anti-cytomegalovirus (CMV) IgG antibodies, were also measured.

Results

Influenza vaccine non-responders showed a tendency of higher frequency of regulatory T-cells (Tregs) before vaccination than responders (1.49 [1.08–1.85] vs. 1.12 [0.94–1.63], respectively, p = 0.061), as well as higher expression of the proliferation marker Ki67 in Tregs and different CD4 and CD8 T-cell maturational subsets. The levels of inflammation-related biomarkers correlated with the frequencies of different proliferating T-cell subsets and with thymic function (e.g., thymic function with D-dimers, r = − 0.442, p = 0.001).

Conclusions

Age-related homeostatic dysregulation involving the proliferation of CD4 and CD8 T-cell subsets, including Tregs, was related to a limited responsiveness to influenza vaccination and a higher inflammatory status in a cohort of elderly people.

Electronic supplementary material

The online version of this article (10.1186/s12979-019-0154-y) contains supplementary material, which is available to authorized users.

Single-cell whole-genome sequencing reveals the functional landscape of somatic mutations in B lymphocytes across the human lifespan

Accumulation of mutations in somatic cells has been implicated as a cause of aging since the 1950s. However, attempts to establish a causal relationship between somatic mutations and aging have been constrained by the lack of methods to directly identify mutational events in primary human tissues. Here we provide genome-wide mutation frequencies and spectra of human B lymphocytes from healthy individuals across the entire human lifespan using a highly accurate single-cell whole-genome sequencing method. We found that the number of somatic mutations increases from <500 per cell in newborns to >3,000 per cell in centenarians. We discovered mutational hotspot regions, some of which, as expected, were located at Ig genes associated with somatic hypermutation (SHM). B cell-specific mutation signatures associated with development, aging, or SHM were found. The SHM signature strongly correlated with the signature found in human B cell tumors, indicating that potential cancer-causing events are already present even in B cells of healthy individuals. We also identified multiple mutations in sequence features relevant to cellular function (i.e., transcribed genes and gene regulatory regions). Such mutations increased significantly during aging, but only at approximately one-half the rate of the genome average, indicating selection against mutations that impact B cell function. This full characterization of the landscape of somatic mutations in human B lymphocytes indicates that spontaneous somatic mutations accumulating with age can be deleterious and may contribute to both the increased risk for leukemia and the functional decline of B lymphocytes in the elderly.

Influenza Virus Vaccination Elicits Poorly Adapted B Cell Responses in Elderly Individuals

Influenza is a leading cause of death in the elderly, and the vaccine protects only a fraction of this population. A key aspect of antibody-mediated anti-influenza virus immunity is adaptation to antigenically distinct epitopes on emerging strains. We examined factors contributing to reduced influenza vaccine efficacy in the elderly and uncovered a dramatic reduction in the accumulation of de novo immunoglobulin gene somatic mutations upon vaccination. This reduction is associated with a significant decrease in the capacity of antibodies to target the viral glycoprotein, hemagglutinin (HA), and critical protective epitopes surrounding the HA receptor-binding domain. Immune escape by antigenic drift, in which viruses generate mutations in key antigenic epitopes, becomes highly exaggerated. Because of this reduced adaptability, most B cells activated in the elderly cohort target highly conserved but less potent epitopes. Given these findings, vaccines driving immunoglobulin gene somatic hypermutation should be a priority to protect elderly individuals.

Immunosenescence Modulation by Vaccination

A decline in immune function is a hallmark of aging that leads to complicated illness from a variety of infectious diseases, cancer and other immune-mediated disorders, and may limit the ability to appropriately respond to vaccination. How vaccines might alter the senescent immune response and what are the immune correlates of protection will be addressed from the perspective of (1) stimulating a previously primed response as in the case of vaccines for seasonal influenza and herpes zoster, (2) priming the response to novel antigens such as pandemic influenza or West Nile virus, (3) vaccination against bacterial pathogens such as pneumococcus and pertussis, (4) vaccines against bacterial toxins such as tetanus and Clostridium difficile, and (5) vaccine approaches to mitigate effects of cytomegalovirus on immune senescence. New or improved vaccines developed over recent years demonstrate the considerable opportunity to improve current vaccines and develop new vaccines as a preventive approach to a variety of diseases in older adults. Strategies for selecting appropriate immunologic targets for new vaccine development and evaluating how vaccines may alter the senescent immune response in terms of potential benefits and risks in the preclinical and clinical trial phases of vaccine development will be discussed.

Older Human B Cells and Antibodies

B cells have a number of different roles in the immune response. Their excellent antigen presentation potential can contribute to the activation of other cells of the immune system, and evidence is emerging that specialized subsets of these cells, that may be increased with age, can influence the cell-mediated immune system in antitumor responses. They can also regulate immune responses, to avoid autoreactivity and excessive inflammation. Deficiencies in regulatory B cells may be beneficial in cancer but will only exacerbate the inflammatory environment that is a hallmark of aging. The B cell role as antibody producers is particularly important, since antibodies perform numerous different functions in different environments. Although studying tissue responses in humans is not as easy as in mice, we do know that certain classes of antibodies are more suited to protecting the mucosal tissues (IgA) or responding to T-independent bacterial polysaccharide antigens (IgG₂) so we can make some inference with respect to tissue-specific immunity from a study of peripheral blood. We can also make inferences about changes in B cell development with age by looking at the repertoire of different B cell populations to see how age affects the selection events that would normally occur to avoid autoreactivity, or increase specificity, to antigen.

Cytokine production in whole-blood cultures following immunization with an influenza vaccine

A clinical trial of a quadrivalent split influenza vaccine was performed in the 2014/15 season. Sixty-four subjects aged 6 months to 18 years were enrolled in order to investigate the relationship between cellular and humoral immune responses. Subjects were categorized into two groups by measuring neutralizing antibodies: non-primed naïve/primed or seroconverted/non-seroconverted groups. Whole-blood cultures were stimulated with the H1N1 split antigen before immunization and one month after the first and second immunizations for subjects < 13 years and before and one month after the first dose for those ≥ 13 years in order to investigate cytokine production. Significant amounts of IL-2, IL-12, IL-13, MCP-1, MIP-1β, and TNF-α were detected from one month after the first dose in the naïve group. In addition to these cytokines, the production of IL-1β, IL-4, IL-6, IL-8, IL-10, IL-17, G-CSF, and IFN-γ was enhanced one month after the second dose. No significant increase was noted in the primed group, except in the production of IL-10. In seroconverted subjects, the production of IL-2, IL-4, IL-8, IL-10, G-CSF, MCP-1, TNF-α, and IFN-γ increased one month after the first dose, which was earlier than in the naïve group, whereas no significant cytokine response was noted in subjects without seroconversion. Subjects ≥ 13 years were primed and the production of G-CSF, IL-4, and IL-1β increased in subjects with seroconversion. Whole-blood cultures were also stimulated with the H3N2 split antigen and similar cytokine profiles were obtained. Many cytokines and chemokines, including inflammatory cytokines, were produced in seroconverted, but not non-seroconverted subjects.

Regulation of miR-181a expression in T cell aging

MicroRNAs have emerged as key regulators in T cell development, activation, and differentiation, with miR-181a having a prominent function. By targeting several signaling pathways, miR-181a is an important rheostat controlling T cell receptor (TCR) activation thresholds in thymic selection as well as peripheral T cell responses. A decline in miR-181a expression, due to reduced transcription of pri-miR-181a, accounts for T cell activation defects that occur with older age. Here we examine the transcriptional regulation of miR-181a expression and find a putative pri-miR-181a enhancer around position 198,904,300 on chromosome 1, which is regulated by a transcription factor complex including YY1. The decline in miR-181a expression correlates with reduced transcription of YY1 in older individuals. Partial silencing of YY1 in T cells from young individuals reproduces the signaling defects seen in older T cells. In conclusion, YY1 controls TCR signaling by upregulating miR-181a and dampening negative feedback loops mediated by miR-181a targets.

Age-related differences in humoral and cellular immune responses after primary immunisation: indications for stratified vaccination schedules

Immunosenescence is characterised by reduced B and T cell responses. Evidence shows that booster vaccinations are less effective in elderly people, but data on the efficacy of primary immunisation are sparse. We conducted a monocentric, open label, phase IV trial to compare immune responses to primary vaccinations using the inactivated, adjuvanted Japanese Encephalitis vaccine by 30 elderly people (mean 69, range 61-78 years) and 30 younger people (mean 24, range 18-30 years). Humoral and cellular immune responses were analysed in relation to age and cytomegalovirus (CMV) seropositivity. Vaccine-specific antibody titres were significantly lower in elderly participants and 47% of them were non- or low responders after the two doses of the vaccine neo-antigen. The reduced humoral immune responses in elderly people correlated with reduced cytokine production, such as interferon gamma (IFN-γ) in vitro, as well as higher frequencies of late-differentiated effector and effector memory T cells and T regulatory cells. These cellular changes and lower antibody titres were particularly prominent in CMV-seropositive elderly participants. If primary vaccination before the age of 60 is not possible, elderly patients may require different vaccination strategies to ensure sufficient long-lasting immunity, such as adapted or accelerated schedules and the use of different adjuvants.

Protective role of γδ T cells in cigarette smoke and influenza infection

Airborne pathogens commonly trigger severe respiratory failure or death in smokers with lung disease. Cigarette smoking compromises the effectiveness of innate immunity against infections but the underlying mechanisms responsible for defective acquired immune responses in smokers remains less clear. We found that mice exposed to chronic cigarette smoke recovered poorly from primary Influenza A pneumonia with reduced type I and II interferons (IFNs) and viral-specific immunoglobulins, but recruited γδ T cells to the lungs that predominantly expressed interleukin 17A (IL-17A). Il-17a^-/- mice exposed to smoke and infected with Influenza A also recruited γδ T cells to the lungs, but in contrast to wild-type mice, expressed increased IFNs, made protective influenza-specific antibodies, and recovered from infection. Depletion of IL-17A with blocking antibodies significantly increased T-bet expression in γδ T cells and improved recovery from acute Influenza A infection in air, but not smoke-exposed mice. In contrast, when exposed to smoke, γδ T cell deficient mice failed to mount an effective immune response to Influenza A and showed increased mortality. Our findings demonstrate a protective role for γδ T cells in smokers and suggest that smoke-induced increase in IL-17A inhibits the transcriptional programs required for their optimal anti-viral responses. Cigarette smoke induces IL-17A expression in the lungs and inhibits γδ T-cell-mediated protective anti-viral immune responses.

Reevaluation of immune activation in the era of cART and an aging HIV-infected population

Biological aging is associated with immune activation (IA) and declining immunity due to systemic inflammation. It is widely accepted that HIV infection causes persistent IA and premature immune senescence despite effective antiretroviral therapy and virologic suppression; however, the effects of combined HIV infection and aging are not well defined. Here, we assessed the relationship between markers of IA and inflammation during biological aging in HIV-infected and -uninfected populations. Antibody response to seasonal influenza vaccination was implemented as a measure of immune competence and relationships between IA, inflammation, and antibody responses were explored using statistical modeling appropriate for integrating high-dimensional data sets. Our results show that markers of IA, such as coexpression of HLA antigen D related (HLA-DR) and CD38 on CD4+ T cells, exhibit strong associations with HIV infection but not with biological age. Certain variables that showed a strong relationship with aging, such as declining naive and CD38+ CD4 and CD8+ T cells, did so regardless of HIV infection. Interestingly, the variable of biological age was not identified in a predictive model as significantly impacting vaccine responses in either group, while distinct IA and inflammatory variables were closely associated with vaccine response in HIV-infected and -uninfected populations. These findings shed light on the most relevant and persistent immune defects during virological suppression with antiretroviral therapy.

Aging-Impaired Filamentous Actin Polymerization Signaling Reduces Alveolar Macrophage Phagocytosis of Bacteria

In elderly patients, bacterial infection often causes severe complications and sepsis. Compared to younger patients, older patients are more susceptible to sepsis caused by respiratory infection. Macrophage (Mϕ) phagocytosis of bacteria plays a critical role in the clearance of pathogens and the initiation of immune responses. It has been suggested that Mϕ exhibit age-related functional alterations, including reduced chemotaxis, phagocytosis, antibacterial defense, and the ability to generate reactive oxygen species. However, the mechanisms behind these changes remain unclear. The present study sought to determine changes in bacterial phagocytosis in aging alveolar Mϕ (AMϕ) and the underlying mechanisms. We show that bacteria initiate cytoskeleton remodeling in AMϕ through interaction with macrophage receptor with collagenous structure (MARCO), a bacterial scavenger receptor. This remodeling, in turn, promotes enhanced cell surface expression of MARCO and bacterial phagocytosis. We further demonstrate that Rac1-GTP mediates MARCO signaling and activates actin-related protein-2/3 complex, an F-actin nucleator, thereby inducing F-actin polymerization, filopodia formation, and increased cell surface expression of MARCO, all of which are essential for the execution of bacteria phagocytosis. However, AMϕ isolated from aging mice exhibit suppressed Rac1 mRNA and protein expression, which resulted in decreases in Rac1-GTP levels and actin-related protein-2/3 activation, as well as subsequent attenuation of F-actin polymerization, filopodia formation, and cell surface expression of MARCO. As a result, bacterial phagocytosis in aging AMϕ is decreased. This study highlights a previously unidentified mechanism by which aging impairs Mϕ phagocytosis of bacteria. Targeting these pathways may improve outcomes of bacterial infection in elderly patients.

Telomere Shortening, Inflammatory Cytokines, and Anti-Cytomegalovirus Antibody Follow Distinct Age-Associated Trajectories in Humans

A number of biological parameters have been cited as hallmarks of immune aging. However, it is not clear whether these multiple biological changes are the result of common underlying aging processes and follow correlated trajectories, or whether the patterns of change for multiple parameters vary across individuals and reflect heterogeneity in the aging process. Here, we have studied parameters of immune system aging through longitudinal analysis of telomere length, inflammatory cytokines, and antibody titer to cytomegalovirus (CMV) in 465 subjects ranging in age from 21 to 88 years at the first visit, with an average of 13 years (7-19 years) follow-up. We observed a highly variable rate of change in telomere length of PBMCs with a relatively slow average rate of telomere shortening (-16 bp/year). Similarly, there were significant increases with age in vivo in three inflammation-related cytokines (interferon gamma, IL-6, and IL-10) and in anti-CMV IgG titer, which varied widely across individuals as well. We further observed positive correlative changes among different inflammatory cytokines. However, we did not find significant correlations among the rate of changes in telomere length, inflammatory cytokines, and anti-CMV IgG titers. Our findings thus reveal that age-related trajectories of telomere attrition, elevated circulating inflammatory cytokines, and anti-CMV IgG are independent and that aging individuals do not show a uniform pattern of change in these variables. Immune aging processes are complex and vary across individuals, and the use of multiple biomarkers is essential to evaluation of biological aging of the immune system.

Frequencies of peripheral immune cells in older adults following seasonal influenza vaccination with an adjuvanted vaccine

As age increases, immune responses and consequently protection following vaccination to seasonal influenza is commonly believed to decrease. Possible drivers of this immune dysfunction include immunosenescence, repeated exposure to the same seasonal influenza antigens, and prior infection with cytomegalovirus (CMV). Here, to determine immune parameters distinguishing vaccine humoral responders (R) from non-responders (NR) following vaccination, we surveyed broad peripheral blood "cellular immune correlates" of older adults vaccinated with Fluad® (an adjuvanted subunit influenza vaccine containing strains H1N1, H3N2 and B). Phenotyping included αβ-T-cells, γδ-T-cells, B-cells and myeloid cells. The frequencies of most of these lymphocyte phenotypes were found to be similar in R and NR, although perhaps counterintuitively, one of the few differences seen between the two groups was higher frequencies of regulatory T-cells in R. These differences were more prominent for responses to the vaccine strains H1N1 and H3N2 than to the B strain, and in CMV-seropositive than CMV-seronegative elderly. Further, frequencies of early-differentiated CD4+ T-cells tended to be higher and frequencies of memory CD4+ T-cells tended to be lower in R than NR. There were also differences in B-cells, with higher frequencies in R compared to NR. To the best of our knowledge, these results are the first to report such differences in elderly people responding or failing to respond to adjuvanted seasonal influenza vaccination.

From lymphopoiesis to plasma cells differentiation, the age-related modifications of B cell compartment are influenced by "inflamm-ageing"

Ageing is a complex process characterized by a general decline in physiological functions with increasing morbidity and mortality. The most important aspect of ageing is the chronic inflammatory status, named "inflamm-ageing", strictly associated with the deterioration of the immune function, termed "immunosenescence". Both are causes of increased susceptibility of elderly to infectious diseases, cancer, dementia, cardiovascular diseases and autoimmunity, and of a decreased response to vaccination. It has been widely demonstrated that ageing has a strong impact on the remodelling of the B cell branch of immune system. The first evident effect is the significant decrease in circulating B cells, primarily due to the reduction of new B cell coming from bone marrow (BM) progenitors, as inflammation directly impacts on B lymphopoiesis. Besides, in aged individuals, there is a shift from naïve to memory immunoglobulins production, accompanied by the impaired ability to produce high affinity protective antibodies against newly encountered antigens. This is accompanied by the increase of expanded clones of B cells, which correlates with poor health status. Age-related modifications also occur in naïve/memory B cells subsets. Indeed, in the elderly, there is a reduction of naïve B cells, accompanied by the expansion of memory B cells that show a senescence-associated phenotype. Finally, elderly show the impaired ability of memory B cells to differentiate into plasma cells. It can be concluded that inflammation is the leading cause of the age-related impairment of B cell compartment, which play certainly a key role in the development of age-related diseases. This makes study of B cells in the aged an important tool for monitoring immunosenescence, chronic inflammatory disorders and the effectiveness of vaccines or pharmacological therapies.

Aging and the immune response to organ transplantation

An increasing number of older people receive organ transplants for various end-stage conditions. Although organ transplantation is an effective therapy for older patients (i.e., older than 65 years of age), such as in end-stage renal disease, this therapy has not been optimized for older patients because of our lack of understanding of the effect of aging and the immune response to organ transplantation. Here, we provide an overview of the impact of aging on both the allograft and the recipient and its effect on the immune response to organ transplantation. We describe what has been determined to date, discuss existing gaps in our knowledge, and make suggestions on necessary future studies to optimize organ transplantation for older people.

Age-related alterations in immune responses to West Nile virus infection

West Nile virus (WNV) is the most important causative agent of viral encephalitis worldwide and an important public health concern in the United States due to its high prevalence, severe disease, and the absence of effective treatments. Infection with WNV is mainly asymptomatic, but some individuals develop severe, possibly fatal, neurological disease. Individual host factors play a role in susceptibility to WNV infection, including genetic polymorphisms in key anti-viral immune genes, but age is the most well-defined risk factor for susceptibility to severe disease. Ageing is associated with distinct changes in immune cells and a decline in immune function leading to increased susceptibility to infection and reduced responses to vaccination. WNV is detected by pathogen recognition receptors including Toll-like receptors (TLRs), which show reduced expression and function in ageing. Neutrophils, monocyte/macrophages and dendritic cells, which first recognize and respond to infection, show age-related impairment of many functions relevant to anti-viral responses. Natural killer cells control many viral infections and show age-related changes in phenotype and functional responses. A role for the regulatory receptors Mertk and Axl in blood-brain barrier permeability and in facilitating viral uptake through phospholipid binding may be relevant for susceptibility to WNV, and age-related up-regulation of Axl has been noted previously in human dendritic cells. Understanding the specific immune parameters and mechanisms that influence susceptibility to symptomatic WNV may lead to a better understanding of increased susceptibility in elderly individuals and identify potential avenues for therapeutic approaches: an especially relevant goal, as the world's populating is ageing.

Differences in Cytokine Production during Aging and Its Relationship with Antimicrobial Peptides Production

Aging is a major health issue due to the increased susceptibility of elderly people to infectious, autoimmune, and cardiovascular diseases. Innate immunity is an important mechanism to avoid primary infections; therefore, decreasing of its activity may lead to development of infections. Antimicrobial peptides (AMPs) are effector molecules of innate immunity that can eliminate microbial invaders. The role that cytokines play in the regulation of these innate immune mechanisms needs to be explored. Serum determinations of Th1, Th2, and Th17 cytokines were performed in order to evaluate their association with AMPs human beta-defensin (HBD)-2 and LL-37 in young adults, elder adults, and elder adults with recurrent infections. Our results showed differences in interleukin (IL)-10 and IL-6 among the different groups. Inverse correlations in serum cytokine levels and HBD-2 production were identified for IL-10, IL-2, IL-4, tumor necrosis factor-α, and IL-6. Also inverse correlations were identified for IL-10, IL-4, and cathelicidin (LL-37). Such results could impact the development of immunomodulators that promote AMP production to prevent and/or contain infectious diseases in this population.

Obesity decreases B cell responses in young and elderly individuals

OBJECTIVE

To evaluate the effects of obesity-associated inflammation on influenza vaccine responses.

METHODS

In young and elderly individuals, both lean and with obesity, antibody responses to influenza vaccination were measured.

RESULTS

A decrease in in vivo vaccine responses, circulating switched memory, and transitional B cells and an increase in pro-inflammatory late/exhausted memory B cells were found. In vitro B cell function was measured by activation-induced cytidine deaminase and E47, markers of optimal antibody responses. Moreover, IL-6 production was increased, whereas IL-10 production was decreased in cultures of B cells from individuals with obesity. Markers of immune activation (TNF-α, TLR4, micro-RNAs) in unstimulated B cells were also found increased and were negatively correlated with B cell function. In order to reveal potential mechanisms, we stimulated B cells from lean individuals in vitro with leptin, the adipokine increased in obesity. Leptin increased phospho-STAT3, crucial for TNF-α production, and decreased phospho-AMPK, the energy sensing enzyme upstream of phospho-p38 MAPK and E47. Leptin-induced phospho-STAT3 and phospho-AMPK levels were similar to those in B cells from individuals with obesity.

CONCLUSIONS

These results demonstrate that leptin can be responsible for decreased B cell function in obesity.

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.”

Key differences in B cell activation patterns and immune correlates among treated HIV-infected patients versus healthy controls following influenza vaccination

BACKGROUND

There is increasing recognition of the role of B cell dysfunction in HIV pathogenesis, but little is known about how these perturbations may influence responses to vaccinations.

METHODS

Healthy controls (n=16) and antiretroviral therapy (ART)-treated aviremic HIV-infected subjects (n=26) receiving standard-of-care annual influenza vaccinations were enrolled in the present study. Total bacterial 16S rDNA levels were assessed by quantitative polymerase chain reactions in plasma. Serologic responses were characterized by ELISA, hemagglutination inhibition assay (HI), and microneutralization, and cell-mediated responses were assessed by ELISPOT (antigen-specific IgG+ antibody-secreting cells (ASCs)) and flow cytometry at pre-vaccination (D0), day 7-10 (D7) and day 14-21 (D14) post-vaccination.

RESULTS

Decreased peripheral CD4+ T cell absolute counts and increased frequencies of cycling and apoptotic B cells were found at baseline in HIV-infected subjects relative to healthy controls. In healthy controls, post-vaccination neutralizing activities were related to the frequencies of vaccine-mediated apoptosis and cycling of B cells, but not to CD4+ T cell counts. In patients, both baseline and post-vaccination neutralizing activities were directly correlated with plasma level of bacterial 16S rDNA. However, overall vaccine responses including antibody titers and fold changes were comparable or greater in HIV-infected subjects relative to healthy controls.

CONCLUSION

B cell function correlates with measures of recall humoral immunity in response to seasonal influenza vaccination in healthy controls but not in ART-treated patients.

Probiotic strain Bacillus subtilis CU1 stimulates immune system of elderly during common infectious disease period: a randomized, double-blind placebo-controlled study

Background

Bacillus probiotics health benefits have been until now quite poorly studied in the elderly population. This study aimed to assess the effects of Bacillus subtilis CU1 consumption on immune stimulation and resistance to common infectious disease (CID) episodes in healthy free-living seniors.

Results

One hundred subjects aged 60–74 were included in this randomized, double-blind, placebo-controlled, parallel-arms study. Subjects consumed either the placebo or the probiotic (2.10⁹B. subtilis CU1 spores daily) by short periodical courses of 10 days intermittently, alternating 18-day course of break. This scheme was repeated 4 times during the study. Symptoms of gastrointestinal and upper/lower respiratory tract infections were recorded daily by the subjects throughout the study (4 months). Blood, saliva and stool samples were collected in a predefined subset of the first forty-four subjects enrolled in the study. B. subtilis CU1 supplementation did not statistically significantly decrease the mean number of days of reported CID symptoms over the 4-month of study (probiotic group: 5.1 (7.0) d, placebo group: 6.6 (7.3) d, P = 0.2015). However, in the subset of forty-four randomized subjects providing biological samples, we showed that consumption of B. subtilis CU1 significantly increased fecal and salivary secretory IgA concentrations compared to the placebo. A post-hoc analysis on this subset showed a decreased frequency of respiratory infections in the probiotc group compared to the placebo group.

Conclusion

Taken together, our study provides evidence that B. subtilis CU1 supplementation during the winter period may be a safe effective way to stimulate immune responses in elderly subjects.

Immunogenicity and sustainability of the immune response in Brazilian HIV-1-infected individuals vaccinated with inactivated triple influenza vaccine

HIV-infected individuals have a higher risk of serious illnesses following infection by infection with influenza. Although anti-influenza vaccination is recommended, immunosuppression may limit their response to active immunization. We followed-up a cohort of HIV-infected individuals vaccinated against influenza to assess the immunogenicity and sustainability of the immune response to vaccination. Individuals were vaccinated 2011 with inactivated triple influenza vaccine (TIV), and they had received in 2010 the monovalent anti-A(H1N1)pdm09 vaccine. The sustainability of the immune response to A(H1N1)pdm09 at 12 months after monovalent vaccination fell, both in individuals given two single or two double doses. For these individuals, A(H1N1)pdm09 component from TIV acted as a booster, raising around 40% the number of seroprotected individuals. Almost 70% of the HIV-infected individuals were already seroprotected to A/H3N2 at baseline. Again, TIV boosted over 90% the seroprotection to A/H3N2. Anti-A/H3N2 titers dropped by 20% at 6 months after vaccination. Pre-vaccination seroprotection rate to influenza B (victoria lineage) was the lowest among those tested, seroconversion rates were higher after vaccination. Seroconversion/protection after TIV vaccination did not differ significantly across categories of clinical and demographic variables. Anti-influenza responses in Brazilian HIV-infected individuals reflected both the previous history of virus circulation in Brazil and vaccination.

Paradoxical changes in innate immunity in aging: recent progress and new directions

Immunosenescence, describing alterations, including decline of immune responses with age, is comprised of inappropriate elevations, decreases, and dysregulated immune responses, leading to more severe consequences of bacterial and viral infections and reduced responses to vaccination. In adaptive immunity, these changes include increased proportions of antigen-experienced B and T cells at the cost of naïve cell populations. Innate immune changes in aging are complex in spanning multiple cell types, activation states, and tissue context. Innate immune responses are dampened in aging, yet there is also a paradoxical increase in certain signaling pathways and cytokine levels. Here, we review recent progress and highlight novel directions for expected advances that can lead the aging field to a new era of discovery that will embrace the complexity of aging in human populations.

N-3 polyunsaturated fatty acids modulate B cell activity in pre-clinical models: Implications for the immune response to infections

B cell antigen presentation, cytokine production, and antibody production are targets of pharmacological intervention in inflammatory and infectious diseases. Here we review recent pre-clinical evidence demonstrating that pharmacologically relevant levels of n-3 polyunsaturated fatty acids (PUFA) derived from marine fish oils influence key aspects of B cell function through multiple mechanisms. N-3 PUFAs modestly diminish B cell mediated stimulation of classically defined naïve CD4(+) Th1 cells through the major histocompatibility complex (MHC) class II pathway. This is consistent with existing data showing that n-3 PUFAs suppress the activation of Th1/Th17 cells through direct effects on helper T cells and indirect effects on antigen presenting cells. Mechanistically, n-3 PUFAs lower antigen presentation and T cell signaling by disrupting the formation of lipid microdomains within the immunological synapse. We then review data to show that n-3 PUFAs boost B cell activation and antibody production in the absence and presence of antigen stimulation. This has potential benefits for several clinical populations such as the aged and obese that have poor humoral immunity. The mode of action by which n-3 PUFA boost B cell activation and antibody production remains unclear, but may involve Th2 cytokines, enhanced production of specialized proresolving lipid mediators, and targeting of protein lateral organization in lipid microdomains. Finally, we highlight evidence to show that different n-3 PUFAs are not biologically equivalent, which has implications for the development of future interventions to target B cell activity.

Delivery of GM-CSF to Protect against Influenza Pneumonia

Background

Since adaptive immunity is thought to be central to immunity against influenza A virus (IAV) pneumonias, preventive strategies have focused primarily on vaccines. However, vaccine efficacy has been variable, in part because of antigenic shift and drift in circulating influenza viruses. Recent studies have highlighted the importance of innate immunity in protecting against influenza.

Methods

Granulocyte-macrophage colony stimulating factor (GM-CSF) contributes to maturation of mononuclear phagocytes, enhancing their capacity for phagocytosis and cytokine production.

Results

Overexpression of granulocyte macrophage-colony stimulating factor (GM-CSF) in the lung of transgenic mice provides remarkable protection against IAV, which depends on alveolar macrophages (AM). In this study, we report that pulmonary delivery of GM-CSF to wild type young and aged mice abrogated mortality from IAV.

Conclusion

We also demonstrate that protection is species specific and human GM-CSF do not protect the mice nor stimulates mouse immunity. We also show that IAV-induced lung injury is the culprit for side-effects of GM-CSF in treating mice after IAV infection, and introduce a novel strategy to deliver the GM-CSF to and retain it in the alveolar space even after IAV infection.

Prolonged proinflammatory cytokine production in monocytes modulated by interleukin 10 after influenza vaccination in older adults

We evaluated in vivo innate immune responses in monocyte populations from 67 young (aged 21-30 years) and older (aged ≥65 years) adults before and after influenza vaccination. CD14(+)CD16(+) inflammatory monocytes were induced after vaccination in both young and older adults. In classical CD14(+)CD16(-) and inflammatory monocytes, production of tumor necrosis factor α and interleukin 6, as measured by intracellular staining, was strongly induced after vaccination. Cytokine production was strongly associated with influenza vaccine antibody response; the highest levels were found as late as day 28 after vaccination in young subjects and were substantially diminished in older subjects. Notably, levels of the anti-inflammatory cytokine interleukin 10 (IL-10) were markedly elevated in monocytes from older subjects before and after vaccination. In purified monocytes, we found age-associated elevation in phosphorylated signal transducer and activator of transcription-3, and decreased serine 359 phosphorylation of the negative IL-10 regulator dual-specificity phosphatase 1. These findings for the first time implicate dysregulated IL-10 production in impaired vaccine responses in older adults.