The impact of immunosenescence on humoral immune response variation after influenza A/H1N1 vaccination in older subjects

Similar humoral responses but distinct CD4+ T cell transcriptomic profiles in older adults elicited by MF59 adjuvanted and high dose influenza vaccines

Older age (≥ 65 years) is associated with impaired responses to influenza vaccination, leading to the preferential recommendation of MF59-adjuvanted (MF59Flu) or high-dose (HDFlu) influenza vaccines for this age group in the United States. Herein, we characterized transcriptomic profiles of CD4+ T cells isolated from 234 recipients (≥ 65 years) of either MF59Flu or HDFlu vaccine, prior to vaccination and 28 days thereafter. We identified 412 and 645 differentially expressed genes (DEGs) in CD4+ T cells of older adults after receiving MF59Flu and HDFlu, respectively. DEGs in CD4+ T cells of MF59Flu recipients were enriched in 14 KEGG pathways, all of which were downregulated. DEGs in CD4+ T cells of HDFlu recipients were enriched in 11 upregulated pathways and 20 downregulated pathways. CD4+ T cells in both vaccine groups shared 50 upregulated genes and 75 downregulated genes, all of which were enriched in 7 KEGG pathways. The remaining 287 and 520 DEGs were specifically associated with MF59Flu and HDFlu, respectively. Unexpectedly, none of these DEGs was significantly correlated with influenza A/H3N2-specific HAI titers, suggesting these DEGs at the individual level may have a limited role in protection against influenza. Our findings emphasize the need for further investigation into other factors influencing immunity against influenza in older adults.

Frequencies of SARS-CoV-2 Spike Protein-Specific Memory B Cells in Human PBMCs, Quantified by ELISPOT Assay

Vaccination against SARS-CoV-2 with coronavirus vaccines that elicit protective immune responses is critical to the prevention of severe disease and mortality associated with SARS-CoV-2 infection. Understanding the adaptive immune responses to SARS-CoV-2 infection and/or vaccination will continue to aid in the development of next-generation vaccines. Studies have shown the important role of SARS-CoV-2-specific antibodies for both disease resolution and prevention of COVID-19 serious sequelae following vaccination. However, antibody responses are short-lived, highlighting the importance of studying antigen-specific B-cell responses to better understand durable immunity and immunologic memory. Since the spike protein is the main target of antibody-producing B cells, we developed a SARS-CoV-2 memory B cell ELISPOT assay to measure the frequencies of spike-specific B cells after COVID-19 infection and/or vaccination. Here, we describe in detail the methodology for using this ELISPOT assay to quantify SARS-CoV-2 spike-specific memory B cells produced by infection and/or vaccination in human PBMC samples. Application of this assay may help better understand and predict SARS-CoV-2 recall immune responses and to develop potential B cell correlates of protection at the methodological level.

Excessive daytime sleepiness is associated with impaired antibody response to influenza vaccination in older male adults

Background

The reduced effectiveness of standard-dose influenza vaccines in persons ≥65 years of age led to the preferential recommendation to use high-dose (HDFlu) or MF59-adjuvanted (MF59Flu) vaccines for this age group. Sleep is an important modulator of immune responses to vaccines and poor sleep health is common in older adults. However, potential effects of poor sleep health on immune responses to influenza vaccination in older adults remain largely unknown.

Methods

We conducted a cohort study of 210 healthy participants age ≥65 years, who received either seasonal high-dose (HDFlu) or MF59-adjuvanted (MF59Flu) influenza vaccine. We assessed sleep characteristics in this cohort by standardized questionnaires and measured the antibody titer against influenza A/H3N2 virus in serum of study participants by hemagglutination inhibition assay on the day of immunization and 28 days thereafter. We then assessed the association between sleep characteristics and antibody titers.

Results

Our results demonstrated that male, but not female, study participants with excessive daytime sleepiness had an impaired influenza A/H3N2-specific antibody response at Day 28 post-vaccination. No other associations were found between antibody titer and other sleep characteristics, including sleep quality and obstructive sleep apnea.

Conclusion

Our results provide an additional and easily measured variable explaining poor vaccine effectiveness in older adults. Our results support that gaining sufficient sleep is a simple non-vaccine interventional approach to improve influenza immune responses in older adults. Our findings extend the literature on the negative influence of excessive daytime sleepiness on immune responses to influenza vaccination in older male adults.

Age-related decline in anti-HBV antibodies in vaccinated kidney transplant recipients

BACKGROUND

Hepatitis B virus (HBV) vaccination is indicated for all end stage kidney disease patients, including all solid organ transplant candidates. Maintenance of adequate immunity is especially important for immunosuppressed solid organ recipients who are at increased risk for donor or community acquired HBV. The impact of age and immunosuppression on long-term maintenance of HBV immunity postvaccination has not been fully investigated.

METHODS

We performed a single-center retrospective study of 96 kidney transplant recipients, transplanted between July 2012 and December 2020, who had Hepatitis B surface antibody (HBsAb) levels measured pretransplantation and 1-year posttransplantation. We compared the change in HBsAb levels stratified by patient's age (<45, 45-60, and >60) and by whether or not the patient received lymphocyte depleting induction therapy.

RESULTS

Our results demonstrate that HBsAb IgG levels vary by age group, decreased significantly at 1-year posttransplant (p < .0001) and were significantly lower in the older cohort (p = .03). Among recipients who received rabbit anti-thymocyte globulin induction (rATG), the log HbsAb levels were significantly lower in the older age group (2.15 in age <45, 1.75 in age 45-60 and 1.47 in age >60, p = .01). Age group (p = .004), recipient HBcAb status (p = .002), and rATG (p = .048) were independently associated with >20% reduction in log HBsAb levels posttransplant.

CONCLUSION

Significant declines in HBsAb levels occur postkidney transplantation, especially in older individuals, thus placing exposed older kidney transplant recipients at greater risk of HBV infection and associated complications.

Immunosenescence: molecular mechanisms and diseases

Infection susceptibility, poor vaccination efficacy, age-related disease onset, and neoplasms are linked to innate and adaptive immune dysfunction that accompanies aging (known as immunosenescence). During aging, organisms tend to develop a characteristic inflammatory state that expresses high levels of pro-inflammatory markers, termed inflammaging. This chronic inflammation is a typical phenomenon linked to immunosenescence and it is considered the major risk factor for age-related diseases. Thymic involution, naïve/memory cell ratio imbalance, dysregulated metabolism, and epigenetic alterations are striking features of immunosenescence. Disturbed T-cell pools and chronic antigen stimulation mediate premature senescence of immune cells, and senescent immune cells develop a proinflammatory senescence-associated secretory phenotype that exacerbates inflammaging. Although the underlying molecular mechanisms remain to be addressed, it is well documented that senescent T cells and inflammaging might be major driving forces in immunosenescence. Potential counteractive measures will be discussed, including intervention of cellular senescence and metabolic-epigenetic axes to mitigate immunosenescence. In recent years, immunosenescence has attracted increasing attention for its role in tumor development. As a result of the limited participation of elderly patients, the impact of immunosenescence on cancer immunotherapy is unclear. Despite some surprising results from clinical trials and drugs, it is necessary to investigate the role of immunosenescence in cancer and other age-related diseases.

Factors associated with humoral immune response in older adults who received egg-free influenza vaccine

BACKGROUND

Immune responses to influenza vaccination tend to be lower among older, frequently vaccinated adults. Use of egg-free influenza vaccines is increasing, but limited data exist on factors associated with their immunogenicity in older adults.

METHODS

Community-dwelling older adults ≥ 56 years of age were enrolled in a prospective, observational study of immunogenicity of 2018-2019 influenza vaccine. Hemagglutination inhibition (HAI) antibody titers were measured pre-vaccination (Day 0) and four weeks after vaccination (Day 28) to calculate geometric mean titers, seropositivity (HAI titers ≥ 1:40), seroconversion (fourfold rise in HAI titer with post-vaccination titer ≥ 1:40) and geometric mean fold rise (GMFR). Linear regression models assessed the association of predictors of GMFR for each vaccine antigen.

RESULTS

Among 91 participants who received egg-free influenza vaccines, 84 (92.3 %) received quadrivalent recombinant influenza vaccine (RIV4, Flublok, Sanofi Pasteur), and 7 (7.7 %) received quadrivalent cell culture-based influenza vaccine (ccIIV4, Flucelvax, Seqirus). Pre-vaccination seropositivity was 52.8 % for A(H1N1), 94.5 % for A(H3N2), 61.5 % for B/Colorado and 48.4 % for B/Phuket. Seroconversion by antigen ranged from 16.5 % for A(H1N1) and B/Colorado to 37.4 % for A(H3N2); 40 participants failed to seroconvert to any antigen. Factors independently associated with higher GMFR in multivariable models included lower pre-vaccination HAI antibody titer for A(H1N1), B/Colorado and B/Phuket, and younger age for A(H1N1).

CONCLUSION

Overall pre-vaccination seropositivity was high and just over half of the cohort seroconverted to ≥ 1 vaccine antigen. Antibody responses were highest among participants with lower pre-vaccination titers. Among older adults with high pre-existing antibody titers, approaches to improve immune responses are needed.

T Cell Transcriptional Signatures of Influenza A/H3N2 Antibody Response to High Dose Influenza and Adjuvanted Influenza Vaccine in Older Adults

Older adults experience declining influenza vaccine-induced immunity and are at higher risk of influenza and its complications. For this reason, high dose (e.g., Fluzone) and adjuvanted (e.g., Fluad) vaccines are preferentially recommended for people age 65 years and older. However, T cell transcriptional activity shaping the humoral immune responses to Fluzone and Fluad vaccines in older adults is still poorly understood. We designed a study of 234 older adults (≥65 years old) who were randomly allocated to receive Fluzone or Fluad vaccine and provided blood samples at baseline and at Day 28 after immunization. We measured the humoral immune responses (hemagglutination inhibition/HAI antibody titer) to influenza A/H3N2 and performed mRNA-Seq transcriptional profiling in purified CD4+ T cells, in order to identify T cell signatures that might explain differences in humoral immune response by vaccine type. Given the large differences in formulation (higher antigen dose vs adjuvant), our hypothesis was that each vaccine elicited a distinct transcriptomic response after vaccination. Thus, the main focus of our study was to identify the differential gene expression influencing the antibody titer in the two vaccine groups. Our analyses identified three differentially expressed, functionally linked genes/proteins in CD4+ T cells: the calcium/calmodulin dependent serine/threonine kinase IV (CaMKIV); its regulator the TMEM38B/transmembrane protein 38B, involved in maintenance of intracellular Ca2+ release; and the transcriptional coactivator CBP/CREB binding protein, as regulators of transcriptional activity/function in CD4+ T cells that impact differences in immune response by vaccine type. Significantly enriched T cell-specific pathways/biological processes were also identified that point to the importance of genes/proteins involved in Th1/Th2 cell differentiation, IL-17 signaling, calcium signaling, Notch signaling, MAPK signaling, and regulation of TRP cation Ca2+ channels in humoral immunity after influenza vaccination. In summary, we identified the genes/proteins and pathways essential for cell activation and function in CD4+ T cells that are associated with differences in influenza vaccine-induced humoral immunity by vaccine type. These findings provide an additional mechanistic perspective for achieving protective immunity in older adults.

Markers of systemic inflammation are positively associated with influenza vaccine antibody responses with a possible role for ILT2(+)CD57(+) NK-cells

Background

With increasing age, overall health declines while systemic levels of inflammatory mediators tend to increase. Although the underlying mechanisms are poorly understood, there is a wealth of data suggesting that this so-called “inflammaging” contributes to the risk of adverse outcomes in older adults. We sought to determine whether markers of systemic inflammation were associated with antibody responses to the seasonal influenza vaccine.

Results

Over four seasons, hemagglutination inhibition antibody titres and ex vivo bulk peripheral blood mononuclear cell (PBMC) responses to live influenza viruses assessed via interferon (IFN)-γ/interleukin (IL)-10 production, were measured pre- and 4-weeks post-vaccination in young adults (n = 79) and older adults randomized to standard- or high-dose inactivated vaccine (n = 612). Circulating tumour necrosis factor (TNF), interleukin (IL)-6 and C-reactive protein (CRP) were also measured pre-vaccination. Post-vaccination antibody titres were significantly associated with systemic inflammatory levels; specifically, IL-6 was positively associated with A/H3N2 titres in young adults (Cohen’s d = 0.36), and in older high-dose, but not standard-dose recipients, all systemic inflammatory mediators were positively associated with A/H1N1, A/H3N2 and B titres (d = 0.10–0.45). We further show that the frequency of ILT2(+)CD57(+) CD56-Dim natural killer (NK)-cells was positively associated with both plasma IL-6 and post-vaccination A/H3N2 titres in a follow-up cohort of older high-dose recipients (n = 63). Pathway analysis suggested that ILT2(+)CD57(+) Dim NK-cells mediated 40% of the association between IL-6 and A/H3N2 titres, which may be related to underlying participant frailty.

Conclusions

In summary, our data suggest a complex relationship amongst influenza vaccine responses, systemic inflammation and NK-cell phenotype in older adults, which depends heavily on age, vaccine dose and possibly overall health status. While our results suggest that “inflammaging” may increase vaccine immunogenicity in older adults, it is yet to be determined whether this enhancement contributes to improved protection against influenza disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-022-00284-x.

Enhancing Immunogenicity of Influenza Vaccine in the Elderly through Intradermal Vaccination: A Literature Analysis

BACKGROUND

Aging and immunosenescence lead to a gradual decline in immune responses in the elderly and the immunogenicity of influenza vaccines in this age group is sub-optimal. Several approaches have been explored to enhance the immunogenicity of influenza vaccines in the elderly, including incorporating vaccine adjuvant, increasing antigen dosage, and changing the route of vaccine administration.

METHOD

We systematically compared the immunogenicity and safety of influenza vaccines administered by intradermal (ID) route and either intramuscular (IM) or subcutaneous (SC) routes in older adults aged ≥ 65.

RESULTS

Of 17 studies included in this analysis, 3 studies compared the immunogenicity of ID vaccination to that of SC vaccination and 14 studies compared ID and IM vaccinations. ID vaccination was typically more immunogenic than both IM and SC routes at the same dosage. Importantly, a minimum of 3 µg of hemagglutinin antigen could be formulated in an ID influenza vaccine without a significant loss of immunogenicity. ID administration of standard-dose, unadjuvanted influenza vaccine was as immunogenic as IM injection of adjuvanted influenza vaccine. Waning of influenza-specific immunity was significant after 6 months, but there was no difference in waning immunity between vaccinations in ID, IM, or SC routes. While ID vaccination elicited local adverse reactions more frequently than other routes, these reactions were mild and lasted for no more than 3 days.

CONCLUSIONS

We conclude that ID vaccination is superior to IM or SC routes and may be a suitable approach to compensate for the reduced immunogenicity observed in elderly adults. We also conclude that the main benefit of ID influenza vaccine lies in its dose-sparing effect. Additional research is still needed to further develop a more immunogenic ID influenza vaccine.

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

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

The Cost-Effectiveness of Vaccination of Older Adults with an MF59-Adjuvanted Quadrivalent Influenza Vaccine Compared to Other Available Quadrivalent Vaccines in Germany

Enhanced quadrivalent influenza vaccines that include an adjuvant (aQIV) or a high dose of antigen (QIV-HD), which stimulate a stronger immune response in older adults than the standard vaccine (QIVe), are now approved. The objective of this research is to compare available vaccines and determine the cost-effectiveness of immunizing persons aged 65 years and above with aQIV compared to QIVe and QIV-HD in Germany. A compartmental transmission model calibrated to outpatient visits for influenza in Germany was used to predict the number of medically attended infections using the three vaccines. The rates of hospitalizations, deaths, and other economic consequences were estimated with a decision tree using German data where available. Based on meta-analysis, the rVE of −2.5% to 8.9% for aQIV versus QIV-HD, the vaccines are similar clinically, but aQIV is cost saving compared to QIV-HD (unit cost of EUR 40.55). All results were most sensitive to changes in vaccine effectiveness. aQIV may be cost-effective compared to QIVe depending on the willingness to pay for additional benefits in Germany. As aQIV and QIV-HD are similar in terms of effectiveness, aQIV is cost saving compared to QIV-HD at current unit prices.

Analysis of Viral and Host Factors on Immunogenicity of 2018, 2019, and 2020 Southern Hemisphere Seasonal Trivalent Inactivated Influenza Vaccine in Adults in Brazil

Annual vaccination against influenza is the best tool to prevent deaths and hospitalizations. Regular updates of trivalent inactivated influenza vaccines (TIV) are necessary due to high mutation rates in influenza viruses. TIV effectiveness is affected by antigenic mismatches, age, previous immunity, and other host factors. Studying TIV effectiveness annually in different populations is critical. The serological responses to Southern-Hemisphere TIV and circulating influenza strains were evaluated in 2018−2020 among Brazilian volunteers, using hemagglutination inhibition (HI) assays. Post-vaccination titers were corrected to account for pre-vaccination titers. Our population achieved >83% post-vaccination seroprotection levels, whereas seroconversion rates ranged from 10% to 46%. TIV significantly enhanced antibody titers and seroprotection against all prior and contemporary vaccine and circulating strains tested. Strong cross-reactive responses were detected, especially between H1N1 subtypes. A/Singapore/INFIMH-16-0019/2016, included in the 2018 TIV, induced the poorest response. Significant titer and seroprotection reductions were observed 6 and 12 months after vaccination. Age had a slight effect on TIV response, whereas previous vaccination was associated with lower seroconversion rates and titers. Despite this, TIV induced high seroprotection for all strains, in all groups. Regular TIV evaluations, based on regional influenza strain circulation, should be conducted and the factors affecting response studied.

Effects of age, sex, serostatus, and underlying comorbidities on humoral response post-SARS-CoV-2 Pfizer-BioNTech mRNA vaccination: a systematic review

With the advent of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic, several vaccines have been developed to mitigate its spread and prevent adverse consequences of the Coronavirus Disease 2019 (COVID-19). The mRNA technology is an unprecedented vaccine, usually given in two doses to prevent SARS-CoV-2 infections. Despite effectiveness and safety, inter-individual immune response heterogeneity has been observed in recipients of mRNA-based vaccines. As a novel disease, the specific immune response mechanism responsible for warding off COVID-19 remains unclear at this point. However, significant evidence suggests that humoral response plays a crucial role in affording immunoprotection and preventing debilitating sequelae from COVID-19. As such, this paper focused on the possible effects of age, sex, serostatus, and comorbidities on humoral response (i.e. total antibodies, IgG, and/or IgA) of different populations post-mRNA-based Pfizer-BioNTech vaccination. A systematic search of literature was performed through PubMed, Cochrane CENTRAL, Google Scholar, Science Direct, medRxiv, and Research Square. Studies were included if they reported humoral response to COVID-19 mRNA vaccines. A total of 32 studies were identified and reviewed, and the percent differences of means of reported antibody levels were calculated for comparison. Findings revealed that older individuals, male sex, seronegativity, and those with more comorbidities mounted less humoral immune response. Given these findings, several recommendations were proposed regarding the current vaccination practices. These include giving additional doses of vaccination for immunocompromised and elderly populations. Another recommendation is conducting clinical trials in giving a combined scheme of mRNA vaccines, protein vaccines, and vector-based vaccines.

Distinct Homologous and Variant-Specific Memory B-Cell and Antibody Response Over Time after SARS-CoV-2 mRNA Vaccination

The durability of protective humoral immunity after SARS-CoV-2 vaccination and infection is largely dependent on the generation and persistence of antigen-specific isotype-switched memory B cells (MBCs) and long-lived plasma cells that reside in the bone marrow and secrete high-affinity neutralizing antibodies. The reactivity of vaccine-induced MBCs to emerging clinically significant SARS-CoV-2 variants of concern (VoCs) is largely unknown. In a longitudinal cohort study (up to 6 months following COVID-19 mRNA vaccination) we measured MBCs in concert with other functional antibody measures. We found statistically significant differences between the frequencies of MBCs responding to homologous and VoC receptor-binding domain/RBDs (Beta, Gamma, and Delta) after vaccination that persisted over time. In concert with a waning antibody response, the reduced MBC response to VoCs could translate to a weaker subsequent recall immune response and increased susceptibility to the emerging SARS-CoV-2 variant strains after vaccination.

The cost-effectiveness of an adjuvanted quadrivalent influenza vaccine in the United Kingdom

In the United Kingdom (UK), both the MF59-adjuvanted quadrivalent influenza vaccine (aQIV) and the high-dose QIV (QIV-HD) are preferred for persons aged 65 years and older but only aQIV is reimbursed by the National Health Service (NHS). The objective was to determine the potential cost-effectiveness of vaccinating adults aged 65 years and above with aQIV compared with QIV-HD in the UK. A dynamic transmission model, calibrated to match infection data from the UK, was used to estimate the impact of vaccination in 10 influenza seasons. Vaccine effectiveness was based on a meta-analysis that concluded the vaccines were not significantly different. Vaccine coverage, physician visits, hospitalizations, deaths, utility losses and NHS costs were estimated using published UK sources. The list price of aQIV was £11.88 while a range of prices were tested for QIV-HD. The price of the trivalent high-dose vaccine (TIV-HD) is £20.00 but a list price for QIV-HD is not yet available. The projected differences between the vaccines in terms of clinical cases and influenza treatment costs are minimal. Our analysis demonstrates that in order to be cost-effective, the price of QIV-HD must be similar to that of aQIV and may range from £7.57 to £12.94 depending on the relative effectiveness of the vaccines. The results of the analysis were most sensitive to variation in vaccine effectiveness and the rate of hospitalization due to influenza. Given the evidence, aQIV is cost-saving unless QIV-HD is priced lower than the existing list price of TIV-HD.

The Effect of Mango Mistletoes (Dendrophthoe pentandra) Leaves Extract on Percentage of CD4+CD28+, CD8+CD28+, and interleukin-2 Levels of Aged Balb/c Mice

BACKGROUND: Population aging is considered to be a global phenomenon today. Age-associated immune system dysfunction or “immunosenescence” is indicated by increased susceptibility to infections and chronic diseases, such as hypertension, diabetes mellitus, autoimmune diseases, heart disease, and atherosclerosis. One of the immunosenescence markers is a significant drop in CD28 and reduced proinflammatory cytokine interleukin-2 (IL-2). The mango mistletoes are deemed to have a better affinity for docking the CD28 and IL-2R receptors of α and β subunits than other plants. AIM: This study aims to determine the effect of ethanol extract of mango mistletoes on IL-2 levels, the percentage of CD4+CD28+, and the percentage of CD8+CD28+ in aged female mice. METHODS: The leaves of mango mistletoes were extracted using 96% ethanol solvent, and the extract was administered to aged female mice (18–20 months) orally with different doses for each group, namely 150, 300, and 600 mg/kg. Mango mistletoe leaves extract was administered once a day for 14 days. Then, the IL-2 levels of the mice were checked from their heart blood samples using Enzyme-Linked Immunosorbent Assay, while the percentages of CD4+CD28+ and CD8+CD28+ were examined from the spleen samples using flow cytometry. RESULTS: The ethanol extract of mango mistletoe leaves was able to increase the percentage of CD4+CD28+ significantly (p < 0.05) at doses of 300 and 600 mg/kg and increase the percentage of CD8+CD28+ significantly (p < 0.05) at a dose of 600 mg/kgBW, while other various doses had a strong enough correlation (r = 0.48) to increase IL-2 levels. CONCLUSION: The ethanol extract of mango mistletoe leaves has the good potential to inhibit the aging process in the immune system, as characterized by an increase in IL-2 levels and the percentage of CD4+CD28+ and CD8+CD28+.

Influenza vaccination: protecting the most vulnerable

Influenza virus infection causes seasonal epidemics and occasional pandemics, leading to huge morbidity and mortality worldwide. Vaccination against influenza is needed annually as protection from constantly mutating strains is required. Groups at high risk of poor outcomes include the elderly, the very young, pregnant women and those with chronic health conditions. However, vaccine effectiveness in the elderly is generally poor due to immunosenescence and may be altered due to "original antigenic sin". Strategies to overcome these challenges in the elderly include high-dose or adjuvant vaccines. Other options include vaccinating healthcare workers and children as this reduces community-level influenza transmission. Current guidelines in the UK are that young children receive a live attenuated nasal spray vaccine, adults aged >65 years receive an adjuvanted trivalent inactivated vaccine and adults aged <65 years with comorbidities receive a quadrivalent inactivated vaccine. The goal of a universal influenza vaccine targeting conserved regions of the virus and avoiding the need for annual vaccination is edging closer with early-phase trials under way.

Sex-specific differences of humoral immunity and transcriptome diversification in older adults vaccinated with inactivated quadrivalent influenza vaccines

Clinical data showed sex variability in the immune response to influenza vaccination, this study aimed to investigate differentially expressed genes (DEGs) that contribute to sex-bias immunity to quadrivalent inactivated influenza vaccines (QIVs) in the elderly. 60 healthy adults aged 60-80 yrs were vaccinated with QIVs, and gene expression was analyzed before and after vaccination. The humoral immunity was analyzed by HAI assay, and the correlation of gene expression patterns of two sex groups with humoral immunity was analyzed. The DEGs involved in type I interferon signaling pathway and complement activation of classical pathway were upregulated within 3 days in females. At Day 28, the immune response showed a male-bias pattern associated with the regulation of protein processing and complement activation of classical pathway. A list of DEGs associated with variant responses to influenza vaccination between females and males were identified by biology-driven clustering. Old females have a greater immune response to QIVs but a rapid antibody decline, while old males have the advantages to sustain a durable response. In addition, we identified genes that may contribute to the sex variations toward influenza vaccination in the aged. Our findings highlight the importance of developing personalized seasonal influenza vaccines.

Aging and CMV discordance are associated with increased immune diversity between monozygotic twins

Background

Broadly, much of variance in immune system phenotype has been linked to the influence of non-heritable factors rather than genetics. In particular, two non-heritable factors: aging and human cytolomegavirus (CMV) infection, have been known to account for significant inter-individual immune variance. However, many specific relationships between them and immune composition remain unclear, especially between individuals over narrower age ranges. Further exploration of these relationships may be useful for informing personalized intervention development.

Results

To address this need, we evaluated 41 different cell type frequencies by mass cytometry and identified their relationships with aging and CMV seropositivity. Analyses were done using 60 healthy individuals, including 23 monozygotic twin pairs, categorized into young (12–31 years) and middle-aged (42–59 years). Aging and CMV discordance were associated with increased immune diversity between monozygotic twins overall, and particularly strongly in various T cell populations. Notably, we identified 17 and 11 cell subset frequencies as relatively influenced and uninfluenced by non-heritable factors, respectively, with results that largely matched those from studies on older-aged cohorts. Next, CD4+ T cell frequency was shown to diverge with age in twins, but with lower slope than in demographically similar non-twins, suggesting that much inter-individual variance in this cell type can be attributed to interactions between genetic and environmental factors. Several cell frequencies previously associated with memory inflation, such as CD27- CD8+ T cells and CD161+ CD4+ T cells, were positively correlated with CMV seropositivity, supporting findings that CMV infection may incur rapid aging of the immune system.

Conclusions

Our study confirms previous findings that aging, even within a relatively small age range and by mid-adulthood, and CMV seropositivity, both contribute significantly to inter-individual immune diversity. Notably, we identify several key immune cell subsets that vary considerably with aging, as well as others associated with memory inflation which correlate with CMV seropositivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-021-00216-1.

Identifying Potential Candidate Hub Genes and Functionally Enriched Pathways in the Immune Responses to Quadrivalent Inactivated Influenza Vaccines in the Elderly Through Co-Expression Network Analysis

Insights into the potential candidate hub genes may facilitate the generation of safe and effective immunity against seasonal influenza as well as the development of personalized influenza vaccines for the elderly at high risk of influenza virus infection. This study aimed to identify the potential hub genes related to the immune induction process of the 2018/19 seasonal quadrivalent inactivated influenza vaccines (QIVs) in the elderly ≥60 years by using weighted gene co-expression network analysis (WGCNA). From 63 whole blood samples from16 elderly individuals, a total of 13,345 genes were obtained and divided into eight co-expression modules, with two modules being significantly correlated with vaccine-induced immune responses. After functional enrichment analysis, genes under GO terms of vaccine-associated immunity were used to construct the sub-network for identification and functional validation of hub genes. MCEMP1 and SPARC were confirmed as the hub genes with an obvious effect on QIVs-induced immunity. The MCEMP1 expression was shown to be negatively correlated with the QIVs-associated reactogenicity within 7 days after vaccination, which could be suppressed by the CXCL 8/IL-8 and exacerbated by the Granzyme-B cytotoxic mediator. Meanwhile, the SPARC expression was found to increase the immune responses to the QIVs and contribute to the persistence of protective humoral antibody titers. These two genes can be used to predict QIVs-induced adverse reaction, the intensity of immune responses, and the persistence of humoral antibody against influenza. This work has shed light on further research on the development of personalized QIVs with appropriate immune responses and long-lasting immunity against the forthcoming seasonal influenza.

The impact of physical frailty on the response to inactivated influenza vaccine in older adults

Physical frailty's impact on hemagglutination inhibition antibody titers (HAI) and peripheral blood mononuclear cell (PBMC) transcriptional responses after influenza vaccination is unclear. Physical frailty was assessed using the 5-item Fried frailty phenotype in 168 community- and assisted-living adults ≥55 years of age during an observational study. Blood was drawn before, 3, 7, and 28 days post-vaccination with the 2017-2018 inactivated influenza vaccine. HAI response to the A/H1N1 strain was measured at Days 0 and 28 using seropositivity, seroconversion, log2 HAI titers, and fold-rise in log2 HAI titers. RNA sequencing of PBMCs from Days 0, 3 and 7 was measured in 28 participants and compared using pathway analyses. Frailty was not significantly associated with any HAI outcome in multivariable models. Compared with non-frail participants, frail participants expressed decreased cell proliferation, metabolism, antibody production, and interferon signaling genes. Conversely, frail participants showed elevated gene expression in IL-8 signaling, T-cell exhaustion, and oxidative stress pathways compared with non-frail participants. These results suggest that reduced effectiveness of influenza vaccine among older, frail individuals may be attributed to immunosenescence-related changes in PBMCs that are not reflected in antibody levels.

Mitochondria, immunosenescence and inflammaging: a role for mitokines?

A global reshaping of the immune responses occurs with ageing, indicated as immunosenescence, where mitochondria and mitochondrial metabolism play an important role. However, much less is known about the role of mitochondrial stress response in this reshaping and in particular of the molecules induced by such response, collectively indicated as mitokines. In this review, we summarize the current knowledge on the role of mitokines in modulating immune response and inflammation focusing on GDF15, FGF21 and humanin and their possible involvement in the chronic age-related low-grade inflammation dubbed inflammaging. Although many aspects of their biology are still controversial, available data suggest that these mitokines have an anti-inflammatory role and increase with age. Therefore, we hypothesize that they can be considered part of an adaptive and integrated immune-metabolic mechanism activated by mitochondrial dysfunction that acts within the framework of a larger anti-inflammatory network aimed at controlling both acute inflammation and inflammaging.

Comparison of influenza hospitalization outcomes among adults, older adults, and octogenarians: a US national population-based study

OBJECTIVES

This study sought to more fully elucidate the age-related trends in influenza mortality with a secondary goal of uncovering implications for treatment and prevention.

METHODS

In this retrospective cohort analysis of data from the Nationwide Readmission Database, patients with influenza as a primary or secondary discharge diagnosis were separated into three age groups: 55 638 adults aged 20-64 years, 36 862 adults aged 65-79 years and 41 806 octogenarians aged ≥80 years. Propensity score (PS) weighting was performed to isolate age from other baseline differences. Crude and PS-weighted hazard ratios (HR) were calculated from the in-hospital all-cause 30-day mortality rate. Admission threshold bias was minimized by comparison of influenza with bacterial pneumonia mortality.

RESULTS

Adults aged 20-64 years experienced higher in-hospital 30-day mortality compared with older adults aged 65-79 years (HR 0.66; 95% CI 0.55-0.79). Octogenarians had the highest mortality rate, but this was statistically insignificant compared with the adult cohort (HR 1.09; 95% CI 0.94-1.27). This trend was not explained by admission threshold bias: the 30-day mortality rate due to in-hospital bacterial pneumonia increased consistently with age (older adult HR 1.45; 95% CI 1.32-1.59; octogenarian HR 1.99; 95% CI 1.82-2.18).

CONCLUSIONS

Adults aged 20-64 years and octogenarians were more likely to experience all-cause 30-day mortality during influenza hospitalization compared with older adults aged 65-79 years. These data emphasize the importance of prevention and suggest the need for more tailored treatment interventions based on risk stratification that includes age.

Association of Lymphopenia With Risk of Mortality Among Adults in the US General Population

Importance

Immune dysregulation can increase the risk of infection, malignant neoplasms, and cardiovascular disease, but improved methods are needed to identify and quantify immunologic hazard in the general population.

Objective

To determine whether lymphopenia is associated with reduced survival in outpatients.

Design, Setting, and Participants

This retrospective cohort study of the National Health and Nutrition Examination Survey (NHANES) included participants enrolled from January 1, 1999, to December 31, 2010, a large outpatient sample representative of the US adult population. Associations were evaluated between lymphopenia and other immunohematologic (IH) markers, clinical features, and survival during 12 years of follow-up, completed on December 31, 2011. Spearman correlations, Cox proportional hazards regression models, and Kaplan-Meier curves were used in univariable and multivariable models, allowing for nonlinear associations with bivariate cubic polynomials. Data were analyzed from September 1, 2018, through July 24, 2019.

Exposures

Absolute lymphocyte counts (ALC), red blood cell distribution width (RDW), and C-reactive protein (CRP) level.

Main Outcomes and Measures

All-cause survival.

Results

Among the 31 178 participants, the median (interquartile range) age at baseline was 45 (30-63) years, 16 093 (51.6%) were women, 16 260 (52.2%) were nonwhite, and overall 12-year rate of survival was 82.8%. Relative lymphopenia (≤1500/μL) and severe lymphopenia (≤1000/μL) were observed in 20.1% and 3.0%, respectively, of this general population and were associated with increased risk of mortality (age- and sex-adjusted hazard ratios [HRs], 1.3 [95% CI, 1.2-1.4] and 1.8 [95% CI, 1.6-2.1], respectively) due to cardiovascular and noncardiovascular causes. Lymphopenia was also associated with worse survival in multivariable models, including traditional clinical risk factors, and this risk intensified when accompanied by bone marrow dysregulation (elevated RDW) and/or inflammation (elevated CRP level). Ten-year mortality ranged from 3.8% to 62.1% based on lymphopenia status, tertile of CRP level, and tertile of RDW. A high-risk IH profile was nearly twice as common as type 2 diabetes (19.3% and 10.0% of participants, respectively) and associated with a 3-fold risk of mortality (HR, 3.2; 95% CI, 2.6-4.0). Individuals aged 70 to 79 years with low IH risk had a better 10-year survival (74.1%) than those who were a decade younger with a high-risk IH profile (68.9%).

Conclusions and Relevance

These findings suggest that lymphopenia is associated with reduced survival independently of and additive to traditional risk factors, especially when accompanied by altered erythropoiesis and/or heightened inflammation. Immune risk may be analyzed as a multidimensional entity derived from routine tests, facilitating precision medicine and population health interventions.

Analyses of Mitochondrial DNA and Immune Phenotyping Suggest Accelerated T-Cell Turnover in Treated HIV

BACKGROUND

HIV infection is associated with premature aging, and mitochondrial integrity is compromised during the aging process. Because mitochondrial toxicity is a consequence of antiretroviral therapies (ARTs), we hypothesized HIV and long-term ART would correlate with immunosenescence and mitochondrial DNA (mtDNA) pathology.

SETTING

Thirteen older HIV-infected individuals (aged >40 years) with virologic suppression (stratified by duration of ART) were compared with 10 uninfected controls well-matched for age.

METHODS

Peripheral blood T-cells were immunophenotyped to measure immune activation, proliferation, and immunosenescence in subsets. mtDNA copies per cell and the relative abundance of mtDNA carrying the "common deletion" (RACD) were quantified by droplet digital polymerase chain reaction.

RESULTS

Immune activation was higher in HIV-infected individuals than HIV-uninfected individuals in mature CD4 T-cell subsets (CD4TTM P = 0.025, CD4TEM P = 0.0020) regardless of ART duration. Cell populations from uninfected individuals were more likely to be more senescent populations in mature CD4 T-cell subsets (TTM P = 0.017), and CD8 (CD8TEMRA+ P = 0.0026). No differences were observed in mtDNA or RACD levels in any CD4 T-cell subsets, while CD8TSCM of infected individuals trended to have more mtDNA (P = 0.057) and reduced RACD (P = 0.0025).

CONCLUSIONS

HIV-infected individuals demonstrated increased immune activation, but reduced senescence in more mature T-cell subsets. Increased mtDNA content and lower RACD in CD8TSCM suggest immune activation driven turnover of these cells in HIV-infected persons.

Human T Cell Differentiation Negatively Regulates Telomerase Expression Resulting in Reduced Activation-Induced Proliferation and Survival

Maintenance of telomeres is essential for preserving T cell proliferative responses yet the precise role of telomerase in human T cell differentiation, function, and aging is not fully understood. Here we analyzed human telomerase reverse transcriptase (hTERT) expression and telomerase activity in six T cell subsets from 111 human adults and found that levels of hTERT mRNA and telomerase activity had an ordered decrease from naïve (TN) to central memory (TCM) to effector memory (TEM) cells and were higher in CD4+ than their corresponding CD8+ subsets. This differentiation-related reduction of hTERT mRNA and telomerase activity was preserved after activation. Furthermore, the levels of hTERT mRNA and telomerase activity were positively correlated with the degree of activation-induced proliferation and survival of T cells in vitro. Partial knockdown of hTERT by an anti-sense oligo in naïve CD4+ cells led to a modest but significant reduction of cell proliferation. Finally, we found that activation-induced levels of telomerase activity in CD4+ TN and TCM cells were significantly lower in old than in young subjects. These findings reveal that hTERT/telomerase expression progressively declines during T cell differentiation and age-associated reduction of activation-induced expression of hTERT/telomerase mainly affects naïve CD4+ T cells and suggest that enhancing telomerase activity could be a strategy to improve T cell function in the elderly.

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.

Influenza vaccination in the elderly: 25 years follow-up of a randomized controlled trial. No impact on long-term mortality

Influenza vaccination is proven effective in preventing influenza. However, long-term effects on mortality have never been supported by direct evidence. In this study we assessed the long-term outcome of influenza vaccination on mortality in the elderly by conducting a 25-year follow-up study of a RCT on the efficacy of influenza vaccination as baseline. The RCT had been conducted in the Netherlands 5 years before vaccination was recommended for those aged >65 and 17 years before recommending it for those aged >60. The RCT included 1838 community-dwelling elderly aged ≥ 60 that had received an intramuscular injection with the inactivated quadrivalent influenza vaccine (n = 927) or placebo (n = 911) during the 1991/1992 winter. In our follow-up study, outcomes included all-cause mortality, influenza-related mortality and seasonal mortality. Unadjusted and adjusted hazard ratios (HRs) were estimated by Cox regression and sub-hazard ratios (SHRs) by competing risk models. Secondary analyses included subgroup analyses by age and disease status. The vital status up to January 1, 2017 was provided in 1800/1838 (98%) of the cases. Single influenza vaccination did not reduce all-cause mortality when compared to placebo (adjusted HR 0.95, 95% CI 0.85−1.05). Also, no differences between vaccination and placebo group were shown for underlying causes of death or seasonal mortality. In those aged 60–64, median survival increased with 20.1 months (95% CI 2.4–37.9), although no effects on all-cause mortality (adjusted HR 0.86, 95% CI 0.72−1.03) could be demonstrated in survival analysis. In conclusion, this study did not demonstrate a statistically significant effect following single influenza vaccination on long-term mortality in community-dwelling elderly in general. We propose researchers designing future studies on influenza vaccination in the elderly to fit these studies for longer-term follow-up, and suggest age-group comparisons in observational research.

Clinical trial registry number:NTR6179.

Heterotypic Neuraminidase Antibodies Against Different A(H1N1) Strains are Elicited after Seasonal Influenza Vaccination

Neuraminidase (NA) content is not standardized in current seasonal influenza vaccines; neither anti-NA antibodies (anti-NA Abs) are measured nor is it well-defined as a correlate of humoral protection. In this work, the presence of NA1 antibodies against classical A(H1N1) and A(H1N1) pdm09 subtypes was studied before and after vaccination with seasonal vaccines containing A/California/07/2009 strain (A(H1N1) pdm09 subtype). By Enzyme-Linked Lectin Assay (ELLA; Consortium for the Standardization of Influenza Seroepidemiology), we analyzed serum samples from two different cohorts (adults and elderly). The presence of anti-NA Abs at titers ≥1/40 against classical A(H1N1) and A(H1N1) pdm09 subtypes were frequently found in both age groups, in 81.3% and 96.3% of adults and elderly, respectively. The higher titers of anti-NA Abs (NAI titers) were detected more frequently against classical A(H1N1) strains according to the expected age when the first flu infection takes place. In this way, an Original Antigenic Sin phenomenon related to NA seems to be part of the immune response against flu. Seasonal-vaccination induced homologous seroconversion against NA of A(H1N1) pdm09 subtype in 52.5% and 55.0%, and increased the Geometric Mean Titers (GMTs) in 70.0% and 78.8% of adults and elderly, respectively. Seasonal vaccination also induced a heterotypic anti-NA Abs response against classical A(H1N1) strains (seroconversion at least in 8.8% and 11.3% of adults and elderly, respectively, and an increase in GMTs of at least 28.0% in both age groups). These anti-NA Abs responses occur even though the seasonal vaccine does not contain a standardized amount of NA. This work demonstrates that seasonal vaccines containing the A(H1N1) pdm09 subtype induce a broad antibody response against NA1, that may be a target for future influenza vaccines. Our study is one of the first to analyze the presence of Abs against NA and the response mediated by NAI titers after seasonal influenza vaccination.

Sex Differences in Older Adults' Immune Responses to Seasonal Influenza Vaccination

Background: Sex differences in immune responses to influenza vaccine may impact efficacy across populations. Methods: In a cohort of 138 older adults (50-74 years old), we measured influenza A/H1N1 antibody titers, B-cell ELISPOT response, PBMC transcriptomics, and PBMC cell compositions at 0, 3, and 28 days post-immunization with the 2010/11 seasonal inactivated influenza vaccine. Results: We identified higher B-cell ELISPOT responses in females than males. Potential mechanisms for sex effects were identified in four gene clusters related to T, NK, and B cells. Mediation analysis indicated that sex-dependent expression in T and NK cell genes can be partially attributed to higher CD4+ T cell and lower NK cell fractions in females. We identified strong sex effects in 135 B cell genes whose expression correlates with ELISPOT measures, and found that cell subset differences did not explain the effect of sex on these genes' expression. Post-vaccination expression of these genes, however, mediated 41% of the sex effect on ELISPOT responses. Conclusions: These results improve our understanding of sexual dimorphism in immunity and influenza vaccine response.

Age-related immunogenicity and reactogenicity of live oral cholera vaccine CVD 103-HgR in a randomized, controlled clinical trial

Aging is accompanied by a decline in immune function which can lead to decreased responses to vaccines. Attenuated recombinant Vibrio cholerae O1 vaccine strain CVD 103-HgR elicits a rapid serum vibriocidal antibody (SVA) response and protects against cholera diarrhea in volunteer challenge studies but has not been studied in older adults. We evaluated CVD 103-HgR (PXVX0200) in adults age 46-64, compared them to previously studied adults age 18-45, and studied age-related immunogenicity across adults 18-64 years of age. Volunteers were randomized to receive a single dose of 1 × 10⁹ CFU of PXVX0200 or placebo. Immunogenicity endpoints included SVA and anti-cholera toxin (CT) antibody levels on days 1, 11, 29, 91 and 181 and lipopolysaccharide (LPS) and CT-specific IgA and IgG memory B cells on days 1, 91 and 181. Safety was assessed by comparing solicited signs and symptoms on days 1-8 and other adverse events through day 181. 2979 volunteers received vaccine, including 291 age 45-64. Day 11 seroconversion occurred in 90.4% of older adults vs 93.5%% of younger adults and met the endpoint of demonstrating non-inferiority between the two groups. Significant increases in LPS-specific IgG and IgA and CT-specific memory IgG memory B cells were seen at days 91 and 181. There appeared to be a continuous age-related decline in SVA seroconversion and geometric mean titers, but not memory B cell responses, across the 18-64 year age range. Most reactogenicity was mild and was more common in the placebo group. PXVX0200 appears safe and immunogenic in older adults. Clinical Trials Registration: clinicaltrials.gov NCT02100631.

Uptake and effectiveness of influenza vaccine in those aged 65 years and older in the United Kingdom, influenza seasons 2010/11 to 2016/17

BackgroundIn 2016/17, seasonal influenza vaccine was less effective in those aged 65 years and older in the United Kingdom. We describe the uptake, influenza-associated mortality and adjusted vaccine effectiveness (aVE) in this age group over influenza seasons 2010/11-2016/17. Methods: Vaccine uptake in 2016/17 and five previous seasons were measured using a sentinel general practitioners cohort in England; the test-negative case-control design was used to estimate pooled aVE by subtype and age group against laboratory-confirmed influenza in primary care from 2010-2017. Results: Vaccine uptake was 64% in 65-69-year-olds, 74% in 70-74-year-olds and 80% in those aged 75 and older. Overall aVE was 32.5% (95% CI: 11.6 to 48.5); aVE by sub-type was 60.8% (95% CI: 33.9 to 76.7) and 50.0% (95% CI: 21.6 to 68.1) against influenza A(H1N1)pdm09 and influenza B, respectively, but only 5.6% (95% CI: - 39.2 to 35.9) against A(H3N2). Against all laboratory-confirmed influenza aVE was 45.2% (95% CI: 25.1 to 60.0) in 65-74 year olds; - 26.2% (95% CI: - 149.3 to 36.0) in 75-84 year olds and - 3.2% (95% CI: - 237.8 to 68.5) in those aged 85 years and older. Influenza-attributable mortality was highest in seasons dominated by A(H3N2). Conclusions: Vaccine uptake with non-adjuvanted, normal-dose vaccines remained high, with evidence of effectiveness against influenza A(H1N1)pdm09 and B, though poor against A(H3N2), particularly in those aged 75 years and older. Forthcoming availability of newly licensed vaccines with wider use of antivirals can potentially further improve prevention and control of influenza in this group.

Strategies to maximize influenza vaccine impact in older adults

Older adults are disproportionately affected by influenza morbidity and mortality. In most high income countries, influenza vaccine policies target persons age ≥65 years for influenza vaccination. Many low-resource settings do not utilize seasonal influenza vaccination. Barriers to influenza prevention among older adults around the globe are multiple and some vary between high- and low-resource settings. To maximize influenza prevention in the older adult population, gaps in influenza vaccination coverage and improvements in vaccine efficacy are needed. The focus of this article is on the data for currently available vaccine strategies to maximize influenza vaccine impact, with a focus on high-resource settings. We also discuss novel influenza vaccine strategies needed for older adults worldwide.

Responders and non-responders to influenza vaccination: A DNA methylation approach on blood cells

Several evidences indicate that aging negatively affects the effectiveness of influenza vaccination. Although it is well established that immunosenescence has an important role in vaccination response, the molecular pathways underlying this process are largely unknown. Given the importance of epigenetic remodeling in aging, here we analyzed the relationship between responsiveness to influenza vaccination and DNA methylation profiles in healthy subjects of different ages. Peripheral blood mononuclear cells were collected from 44 subjects (age range: 19-90 years old) immediately before influenza vaccination. Subjects were subsequently classified as responders or non-responders according to hemagglutination inhibition assay 4-6 weeks after the vaccination. Baseline whole genome DNA methylation in peripheral blood mononuclear cells was analyzed using the Illumina® Infinium 450 k microarray. Differential methylation analysis between the two groups (responders and non-responders) was performed through an analysis of variance, correcting for age, sex and batch. We identified 83 CpG sites having a nominal p-value <.001 and absolute difference in DNA methylation of at least 0.05 between the two groups. For some CpG sites, we observed age-dependent decrease or increase in methylation, which in some cases was specific for the responders and non-responders groups. Finally, we divided the cohort in two subgroups including younger (age < 50) and older (age ≥ 50) subjects and compared DNA methylation between responders and non-responders, correcting for sex and batch in each subgroup. We identified 142 differentially methylated CpG sites in the young subgroup and 305 in the old subgroup, suggesting a larger epigenetic remodeling at older ages. Interestingly, some of the differentially methylated probes mapped in genes involved in immunosenescence (CD40) and in innate immunity responses (CXCL16, ULK1, BCL11B, BTC). In conclusion, the analysis of epigenetic landscape can shed light on the biological basis of vaccine responsiveness during aging, possibly providing new appropriate biomarkers of this process.

Transcriptomic signatures of cellular and humoral immune responses in older adults after seasonal influenza vaccination identified by data-driven clustering

PBMC transcriptomes after influenza vaccination contain valuable information about factors affecting vaccine responses. However, distilling meaningful knowledge out of these complex datasets is often difficult and requires advanced data mining algorithms. We investigated the use of the data-driven Weighted Gene Correlation Network Analysis (WGCNA) gene clustering method to identify vaccine response-related genes in PBMC transcriptomic datasets collected from 138 healthy older adults (ages 50-74) before and after 2010-2011 seasonal trivalent influenza vaccination. WGCNA separated the 14,197 gene dataset into 15 gene clusters based on observed gene expression patterns across subjects. Eight clusters were strongly enriched for genes involved in specific immune cell types and processes, including B cells, T cells, monocytes, platelets, NK cells, cytotoxic T cells, and antiviral signaling. Examination of gene cluster membership identified signatures of cellular and humoral responses to seasonal influenza vaccination, as well as pre-existing cellular immunity. The results of this study illustrate the utility of this publically available analysis methodology and highlight genes previously associated with influenza vaccine responses (e.g., CAMK4, CD19), genes with functions not previously identified in vaccine responses (e.g., SPON2, MATK, CST7), and previously uncharacterized genes (e.g. CORO1C, C8orf83) likely related to influenza vaccine-induced immunity due to their expression patterns.

An Explorative Biomarker Study for Vaccine Responsiveness after a Primary Meningococcal Vaccination in Middle-Aged Adults

Introduction

Prevention of infectious diseases in the elderly is essential to establish healthy aging. Yet, immunological aging impairs successful vaccination of the elderly. Predictive biomarkers for vaccine responsiveness in middle-aged adults may help to identify responders and non-responders before reaching old age. Therefore, we aimed to determine biomarkers associated with low and high responsiveness toward a primary vaccination in middle-aged adults, for which a tetravalent meningococcal vaccine was used as a model.

Methods

Middle-aged adults (50–65 years of age, N = 100), receiving a tetravalent meningococcal vaccination, were divided into low and high responders using the functional antibody titers at 28 days postvaccination. A total of 48 parameters, including absolute numbers of immune cells and serum levels of cytokines and biochemical markers, were determined prevaccination in all participants. Heat maps and multivariate redundancy analysis (RDA) were used to reveal immune phenotype characteristics and associations of the low and high responders.

Results

Several significant differences in prevaccination immune markers were observed between the low and high vaccine responders. Moreover, RDA analysis revealed a significant association between the prevaccination immune phenotype and vaccine responsiveness. In particular, our analysis pointed at high numbers of CD4 T cells, especially naïve CD4 and regulatory T subsets, to be associated with low vaccine responsiveness. In addition, low responders showed lower prevaccination IL-1Ra levels than high responders.

Conclusion

This explorative biomarker study shows associations between the prevaccination immune phenotype and vaccine responsiveness after a primary meningococcal vaccination in middle-aged adults. Consequently, these results provide a basis for predictive biomarker discovery for vaccine responsiveness that will require validation in larger cohort studies.

Detection and Quantification of Influenza A/H1N1 Virus-Specific Memory B Cells in Human PBMCs Using ELISpot Assay

Immune response following subsequent encounter of viruses (and vaccines) relies largely on the pool and frequencies of antigen-specific memory B cells. In addition to antibody titers, the reliable measurement of these cells in human blood (peripheral blood mononuclear cells/PBMCs or purified B cells) provides valuable information on the preparedness of the adaptive immune system to respond to infection or vaccines, and potentially supports the discovery of new quantitative correlates of protection. The Mayo Clinic Vaccine Research Group has developed and optimized a high-throughput ELISPOT-based assay for the quantification of influenza A/H1N1 virus-specific memory B cells in human PBMCs. Here, we present the materials and detailed methodology for using this assay on cryopreserved cells for the measurement of recall humoral immunity readiness (antigen-specific memory B cell frequencies) after influenza vaccination. This assay could be readily adapted to other influenza virus strains and other respiratory viruses and vaccines for use in systems biology and larger population-based studies.

Skin immunization by microneedle patch overcomes statin-induced suppression of immune responses to influenza vaccine

Recent studies indicated that in elderly individuals, statin therapy is associated with a reduced response to influenza vaccination. The present study was designed to determine effects on the immune response to influenza vaccination induced by statin administration in a mouse model, and investigate potential approaches to improve the outcome of vaccination on the background of statin therapy. We fed middle aged BALB/c mice a high fat “western” diet (WD) alone or supplemented with atorvastatin (AT) for 14 weeks, and control mice were fed with the regular rodent diet. Mice were immunized with a single dose of subunit A/Brisbane/59/07 (H1N1) vaccine, either systemically or with dissolving microneedle patches (MNPs). We observed that a greater age-dependent decline in the hemagglutinin inhibition titers occurred in systemically-immunized mice than in MNP- immunized mice. AT dampened the antibody response in the animals vaccinated by either route of vaccine delivery. However, the MNP-vaccinated AT-treated animals had ~20 times higher total antibody levels to the influenza vaccine than the systemically vaccinated group one month postvaccination. We propose that microneedle vaccination against influenza provides an approach to ameliorate the immunosuppressive effect of statin therapy observed with systemic immunization.

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody production pre- and post-vaccination is required to understand vaccine-induced immunity. This article describes a reliable point-by-point protocol to determine influenza-specific antibody titers. The first protocol describes a method to specify the antigen amounts required for hemagglutination, which standardizes the concentrations for subsequent usage in the second protocol (hemagglutination assay, HA assay). The second protocol describes the quantification of influenza-specific antibody titers against different viral strains by using a serial dilution of human serum or cell culture supernatants (hemagglutination inhibition assay, HI assay). As an applied example, we show the antibody response of a healthy cohort, which received a trivalent inactivated influenza vaccine. Additionally, the cross-reactivity between the different influenza viruses is shown and methods to minimize cross-reactivity by using different types of animal red blood cells (RBCs) are explained. The discussion highlights advantages and disadvantages of the presented assays and how the determination of influenza-specific antibody titers can improve the understanding of vaccine-related immunity.

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.

Effects of prior influenza virus vaccination on maternal antibody responses: Implications for achieving protection in the newborns

BACKGROUND

In the US, influenza vaccination is recommended annually to everyone ≥6months. Prior receipt of influenza vaccine can dampen antibody responses to subsequent vaccination. This may have implications for pregnant women and their newborns, groups at high risk for complications from influenza infection.

OBJECTIVE

This study examined effects of prior vaccination on maternal and cord blood antibody levels in a cohort of pregnant women in the US.

STUDY DESIGN

Influenza antibody titers were measured in 141 pregnant women via the hemagglutination inhibition (HAI) assay prior to receipt of quadrivalent influenza vaccine, 30days post-vaccination, and at delivery (maternal and cord blood). Logistic regression analyses adjusting for age, BMI, parity, gestational age at vaccination, and year of vaccination compared HAI titers, seroprotection, and seroconversion in women with versus without vaccination in the prior year.

RESULTS

Compared to those without vaccination in the previous year (n=50), women with prior vaccination (n=91) exhibited higher baseline antibody titers and/or seroprotection rates against all four strains after controlling for covariates. Prior vaccination also predicted lower antibody responses and seroconversion rates at one month post-vaccination. However, at delivery, there were no significant differences in antibody titers or seroprotection rates in women or newborns, and no meaningful differences in the efficiency of antibody transfer, as indicated by the ratio of cord blood to maternal antibody titers at the time of delivery.

CONCLUSION

In this cohort of pregnant women, receipt of influenza vaccine the previous year predicted higher baseline antibody titers and decreased antibody responses at one month post-vaccination against all influenza strains. However, prior maternal vaccination did not significantly affect either maternal antibody levels at delivery or antibody levels transferred to the neonate. This study is registered with the NIH as a clinical trial (NCT02148874).

Factors affecting immune responses to the influenza vaccine

Annual administration of the seasonal influenza vaccine is strongly recommended to reduce the burden of disease, particularly for persons at the highest risk for the viral infection. Even during years when there is a good match between the vaccine and circulating strains, host-related factors such as age, preexisting immunity, genetic polymorphisms, and the presence of chronic underlying conditions may compromise influenza vaccine responsiveness. The application of new methodologies and large-scale profiling technologies are improving the ability to measure vaccine immunogenicity and our understanding of the immune mechanisms by which vaccines induce protective immunity. This review attempts to summarize the general concepts of how host factors can contribute to the heterogeneity of immune responses induced by influenza vaccines.

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.

Integration of Immune Cell Populations, mRNA-Seq, and CpG Methylation to Better Predict Humoral Immunity to Influenza Vaccination: Dependence of mRNA-Seq/CpG Methylation on Immune Cell Populations

The development of a humoral immune response to influenza vaccines occurs on a multisystems level. Due to the orchestration required for robust immune responses when multiple genes and their regulatory components across multiple cell types are involved, we examined an influenza vaccination cohort using multiple high-throughput technologies. In this study, we sought a more thorough understanding of how immune cell composition and gene expression relate to each other and contribute to interindividual variation in response to influenza vaccination. We first hypothesized that many of the differentially expressed (DE) genes observed after influenza vaccination result from changes in the composition of participants' peripheral blood mononuclear cells (PBMCs), which were assessed using flow cytometry. We demonstrated that DE genes in our study are correlated with changes in PBMC composition. We gathered DE genes from 128 other publically available PBMC-based vaccine studies and identified that an average of 57% correlated with specific cell subset levels in our study (permutation used to control false discovery), suggesting that the associations we have identified are likely general features of PBMC-based transcriptomics. Second, we hypothesized that more robust models of vaccine response could be generated by accounting for the interplay between PBMC composition, gene expression, and gene regulation. We employed machine learning to generate predictive models of B-cell ELISPOT response outcomes and hemagglutination inhibition (HAI) antibody titers. The top HAI and B-cell ELISPOT model achieved an area under the receiver operating curve (AUC) of 0.64 and 0.79, respectively, with linear model coefficients of determination of 0.08 and 0.28. For the B-cell ELISPOT outcomes, CpG methylation had the greatest predictive ability, highlighting potentially novel regulatory features important for immune response. B-cell ELISOT models using only PBMC composition had lower performance (AUC = 0.67), but highlighted well-known mechanisms. Our analysis demonstrated that each of the three data sets (cell composition, mRNA-Seq, and DNA methylation) may provide distinct information for the prediction of humoral immune response outcomes. We believe that these findings are important for the interpretation of current omics-based studies and set the stage for a more thorough understanding of interindividual immune responses to influenza vaccination.

Paradoxical aging in HIV: immune senescence of B Cells is most prominent in young age

Combination antiretroviral therapies (cART)can lead to normal life expectancy in HIV-infected persons, and people aged >50 yrs represent the fastest growing HIV group. Although HIV and aging are independently associated with impaired humoral immunity, immune status in people aging with HIV is relatively unexplored. In this study influenza vaccination was used to probe age associated perturbations in the B cell compartment of HIV-negative "healthy controls" (HC) and virologically controlled HIV-infected participants on cART (HIV) (n=124), grouped by age as young (<40 yrs), middle-aged (40-59yrs) or old (>60 yrs). H1N1 antibody response at d21 post-vaccination correlated inversely with age in both HC and HIV. Immunophenotyping of cryopreserved PBMC demonstrated increased frequencies of double negative B cells and decreased plasmablasts in old compared to young HC. Remarkably, young HIV were different from young HC but similar to old HC in B cell phenotype, influenza specific spontaneous (d7) or memory (d21) antibody secreting cells. We conclude that B cell immune senescence is a prominent phenomenon in young HIV in comparison to young HC, but distinctions between old HIV and old HC are less evident though both groups manifest age-associated B cell dysfunction.

Lifestyle, socioeconomic characteristics, and medical history of elderly persons who receive seasonal influenza vaccination in a tax-supported healthcare system

BACKGROUND

Observational studies on effectiveness of influenza vaccination in the elderly are thought to be biased by healthier lifestyles and higher socioeconomic status among vaccinated vs. unvaccinated persons. We examined this hypothesis in a uniform tax-supported health care system with free-of-charge influenza vaccination to the elderly.

METHODS

We conducted a cross-sectional study among Danes aged 65-79years participating in a survey. We compared elderly persons with and without a recent (within six months) influenza vaccination in terms of (i) lifestyle and socioeconomic characteristics obtained from the survey and (ii) health factors including medical history provided by Danish registries. We compared the prevalence of study variables among vaccinated and unvaccinated persons using age- and sex-adjusted prevalence ratios (aPRs) with 95% confidence intervals (CIs).

RESULTS

Among the 4237 elderly persons completing the survey, 1718 (41%) had received an influenza vaccination. Vaccinated persons had more comorbidity than unvaccinated persons (aPR for high comorbidity level: 1.51 95% CI 1.24-1.84), were less likely to never have smoked (aPR: 0.88, 95% CI 0.80-0.97), and had a higher prevalence of physical inactivity (aPR: 1.08, 95% CI 1.03-1.13). Levels of education and income were similar in the two groups. Vaccinated persons had a higher prevalence of major physical limitations (aPR: 1.40, 95% CI 1.17-1.66) and need for assistance with activities of daily living (aPR: 1.29, 95% CI 1.13-1.47).

CONCLUSION

Elderly influenza vaccinated persons were not healthier in terms of lifestyle and burden of disease, did not have a higher socioeconomic status, and were more frail than unvaccinated persons.

Immunosenescence-Related Transcriptomic and Immunologic Changes in Older Individuals Following Influenza Vaccination

The goal of annual influenza vaccination is to reduce mortality and morbidity associated with this disease through the generation of protective immune responses. The objective of the current study was to examine markers of immunosenescence and identify immunosenescence-related differences in gene expression, gene regulation, cytokine secretion, and immunologic changes in an older study population receiving seasonal influenza A/H1N1 vaccination. Surprisingly, prior studies in this cohort revealed weak correlations between immunosenescence markers and humoral immune response to vaccination. In this report, we further examined the relationship of each immunosenescence marker (age, T cell receptor excision circle frequency, telomerase expression, percentage of CD28⁻ CD4⁺ T cells, percentage of CD28⁻ CD8⁺ T cells, and the CD4/CD8 T cell ratio) with additional markers of immune response (serum cytokine and chemokine expression) and measures of gene expression and/or regulation. Many of the immunosenescence markers indeed correlated with distinct sets of individual DNA methylation sites, miRNA expression levels, mRNA expression levels, serum cytokines, and leukocyte subsets. However, when the individual immunosenescence markers were grouped by pathways or functional terms, several shared biological functions were identified: antigen processing and presentation pathways, MAPK, mTOR, TCR, BCR, and calcium signaling pathways, as well as key cellular metabolic, proliferation and survival activities. Furthermore, the percent of CD4⁺ and/or CD8⁺ T cells lacking CD28 expression also correlated with miRNAs regulating clusters of genes known to be involved in viral infection. Integrated (DNA methylation, mRNA, miRNA, and protein levels) network biology analysis of immunosenescence-related pathways and genesets identified both known pathways (e.g., chemokine signaling, CTL, and NK cell activity), as well as a gene expression module not previously annotated with a known function. These results may improve our ability to predict immune responses to influenza and aid in new vaccine development, and highlight the need for additional studies to better define and characterize immunosenescence.

Immunogenicity of Varicella Vaccine and Immunologic Predictors of Response in a Cohort of Elderly Nursing Home Residents

BACKGROUND

 Little is known about the immunogenicity of live-attenuated Oka/Merck varicella zoster virus (VZV)-containing vaccine (hereafter, "varicella vaccine") in frail nursing homes residents nor about immune phenotypes associated with a response.

METHODS

 A cohort of 190 frail nursing home residents aged 80-102 years and a cohort of 50 community-dwelling seniors aged 60-75 years (a comparison group) received varicella vaccine. Interferon γ (IFN-γ) enzyme-linked immunospot assays were performed before and 6 weeks after vaccination. Cellular markers of immunosenescence were measured in the nursing home elderly.

RESULTS

 The average number of IFN-γ spot-forming cells at baseline was significantly lower in the elderly nursing home residents than in the community-dwelling seniors. However, following vaccination, the VZV immune response increased in both cohorts, and no difference was noted in the fold difference of the response between the 2 cohorts. Upon further examination of the elderly nursing home residents, we found that higher frequencies of regulatory T cells and cytomegalovirus-specific CD4⁺ T cells correlated negatively with the magnitude of VZV-specific responses.

CONCLUSIONS

 The Oka/Merck varicella vaccine induces VZV immunity in elderly nursing home residents that is similar to that produced in community-dwelling seniors.

CLINICAL TRIALS REGISTRATION

 NCT01328548.

Gene signatures associated with adaptive humoral immunity following seasonal influenza A/H1N1 vaccination

This study aimed to identify gene expression markers shared between both influenza hemagglutination-inhibition (HAI) and virus-neutralization antibody (VNA) responses. We enrolled 158 older subjects who received the 2010–2011 trivalent inactivated influenza vaccine (TIV). Influenza-specific HAI and VNA titers, and mRNA-sequencing were performed using blood samples obtained at Days 0, 3 and 28 post-vaccination. For antibody response at Day 28 vs Day 0, several genesets were identified as significant in predictive models for HAI (n=7) and VNA (n=35) responses. Five genesets (comprising the genes MAZ, TTF, GSTM, RABGGTA, SMS, CA, IFNG, and DOPEY) were in common for both HAI and VNA. For response at Day 28 vs Day 3, many genesets were identified in predictive models for HAI (n=13) and VNA (n=41). Ten genesets (comprising biologically related genes, such as MAN1B1, POLL, CEBPG, FOXP3, IL12A, TLR3, TLR7, and others) were shared between HAI and VNA. These identified genesets demonstrated a high degree of network interactions and likelihood for functional relationships. Influenza-specific HAI and VNA responses demonstrated a remarkable degree of similarity. Although unique geneset signatures were identified for each humoral outcome, several genesets were determined to be in common with both HAI and VNA response to influenza vaccine.