B cells and aging: molecules and mechanisms

Tobacco exposure, but not aging, shifts the frequency of peripheral blood B cell subpopulations

Several disturbances in T-cell mediated immunity have been described during aging, but immunosenescence of the B-cell compartment is less well elucidated. The peripheral blood B-cell compartment (CD19+) can be split into six main subpopulations according to the cell surface markers IgD, CD27, CD24, and CD38: Transitional, naïve, unswitched, switched, double negative and plasmablasts. We thus aimed to verify whether shifts in these subsets occur during healthy and pathological aging. We recruited three groups of aged people (> 60 years old), healthy, COPD patients, and smokers without altered pulmonary function test, and a fourth group of individuals 18-40 years old (youngs). Total B-cells percentage and absolute number were similar among the healthy aged, COPD patients, and youngs, but the smokers showed significantly higher absolute numbers. While all six B-cell subset percentages were comparable among the healthy aged, COPD patients, and youngs, smokers showed significantly higher percentages of switched B-cells and reduced naïve B-cells than the other three groups, resulting in an inverted naive:switched ratio. Analysis of the cell subset absolute numbers showed a similar trend. Overall, our results suggest that aging drives milder alterations in the distribution of peripheral blood B-cell subpopulations than in the T-cell compartment. We suggest that it is the T-cell immunosenescence that most contributes to the poor humoral immune responses in the elderly, vaccine responses included. Surprisingly it was the smokers who showed significant alterations when compared with the youngs, healthy aged, and aged COPD patients, probably as a result of the chronic immune stimulation described in active smoking subjects.

Immune aging in annual killifish

Turquoise killifish (Nothobranchius furzeri) evolved a naturally short lifespan of about six months and exhibit aging hallmarks that affect multiple organs. These hallmarks include protein aggregation, telomere shortening, cellular senescence, and systemic inflammation. Turquoise killifish possess the full spectrum of vertebrate-specific innate and adaptive immune system. However, during their recent evolutionary history, they lost subsets of mucosal-specific antibody isoforms that are present in other teleosts. As they age, the immune system of turquoise killifish undergoes dramatic cellular and systemic changes. These changes involve increased inflammation, reduced antibody diversity, an increased prevalence of pathogenic microbes in the intestine, and extensive DNA damage in immune progenitor cell clusters. Collectively, the wide array of age-related changes occurring in turquoise killifish suggest that, despite an evolutionary separation spanning hundreds of millions of years, teleosts and mammals share common features of immune system aging. Hence, the spontaneous aging observed in the killifish immune system offers an excellent opportunity for discovering fundamental and conserved aspects associated with immune system aging across vertebrates. Additionally, the species' naturally short lifespan of only a few months, along with its experimental accessibility, offers a robust platform for testing interventions to improve age-related dysfunctions in the whole organism and potentially inform the development of immune-based therapies for human aging-related diseases.

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

The immunobiology of SARS-CoV-2 infection and vaccine responses: potential influences of cross-reactive memory responses and aging on efficacy and off-target effects

Immune responses to both SARS-CoV-2 infection and its associated vaccines have been highly variable within the general population. The increasing evidence of long-lasting symptoms after resolution of infection, called post-acute sequelae of COVID-19 (PASC) or "Long COVID," suggests that immune-mediated mechanisms are at play. Closely related endemic common human coronaviruses (hCoV) can induce pre-existing and potentially cross-reactive immunity, which can then affect primary SARS-CoV-2 infection, as well as vaccination responses. The influence of pre-existing immunity from these hCoVs, as well as responses generated from original CoV2 strains or vaccines on the development of new high-affinity responses to CoV2 antigenic viral variants, needs to be better understood given the need for continuous vaccine adaptation and application in the population. Due in part to thymic involution, normal aging is associated with reduced naïve T cell compartments and impaired primary antigen responsiveness, resulting in a reliance on the pre-existing cross-reactive memory cell pool which may be of lower affinity, restricted in diversity, or of shorter duration. These effects can also be mediated by the presence of down-regulatory anti-idiotype responses which also increase in aging. Given the tremendous heterogeneity of clinical data, utilization of preclinical models offers the greatest ability to assess immune responses under a controlled setting. These models should now involve prior antigen/viral exposure combined with incorporation of modifying factors such as age on immune responses and effects. This will also allow for mechanistic dissection and understanding of the different immune pathways involved in both SARS-CoV-2 pathogen and potential vaccine responses over time and how pre-existing memory responses, including potential anti-idiotype responses, can affect efficacy as well as potential off-target effects in different tissues as well as modeling PASC.

Ageing on the impact of distribution about preformed anti-HLA and anti-MICA antibody specificities in recipients prior to initial HSCT from East China

BACKGROUND

With the development of Hematopoietic Stem Cell Transplantation (HSCT) technology, increasing numbers of elderly patients were undergoing allogeneic HSCT and elderly patients with hematologic malignancies could benefit most from it. Preformed donor-specific human leukocyte antigen (HLA) antibodies (DSA) were associated with graft failure in HLA-mismatched allogeneic HSCT and the absence of DSA was the main criterion of selecting the donor. Except for sensitization events such as transfusion, pregnancy or previous transplantation, ageing affects the humoral immune response both quantitatively and qualitatively. To evaluate the prevalence and distribution of anti-HLA and antibodies of MHC class I chain related antigens A (MICA) specificities in different age groups before initial HSCT would provide HLA and MICA specific antibody profiles under the impact of ageing, which could provide meaningful information in the process of selecting suitable HLA-mismatched donors by avoiding preformed DSA.

RESULTS

There were no significant differences in the distribution of anti-HLA class I, class II and anti-MICA antibodies among the three age groups in this study except that a significant lower negative ratio of anti-HLA class I, class II antibodies and higher positive rate of MICA antibodies with maximum mean fluorescent intensity (MFI) > 5000 in the elderly than in young age group. The distribution of antibody specificities against HLA -A, -B, -C, -DR, -DQ, -DP and MICA antigens in the three age groups were generally consistent. The anti-HLA class I antibody specificities with higher frequencies were A80,A68;B76,B45;Cw17, which were unlikely to become DSA in Chinese. Anti-HLA class II antibody specificities were more likely to become potential DSA than class I.DR7, DR9, DQ7, DQ8 and DQ9 were most likely to become potential DSA.

CONCLUSIONS

The prevalence of anti-HLA and anti-MICA antibodies increased slightly as age increased. While ageing had a small impact on the distribution of antibody specificity frequencies against HLA-A, -B, -C, -DR,-DQ, -DP and MICA antigens in recipients awaiting initial HSCT from East China. The risk of developing preformed DSA was basically consistent in the three age groups and the elderly group might be more favorable in HLA-mismatched HSCT due to higher positive rate of anti-MICA antibody.

Constitutively active CaMKII Drives B lineage acute lymphoblastic leukemia/lymphoma in tp53 mutant zebrafish

Acute lymphoblastic leukemia/lymphoma (ALL) is the most common pediatric cancer and is a malignancy of T or B lineage lymphoblasts. Dysregulation of intracellular Ca2+ levels has been observed in patients with ALL, leading to improper activation of downstream signaling. Here we describe a new zebrafish model of B ALL, generated by expressing human constitutively active CaMKII (CA-CaMKII) in tp53 mutant lymphocytes. In this model, B cell hyperplasia in the kidney marrow and spleen progresses to overt leukemia/lymphoma, with only 29% of zebrafish surviving the first year of life. Leukemic fish have reduced productive genomic VDJ recombination in addition to reduced expression and improper splicing of ikaros1, a gene often deleted or mutated in patients with B ALL. Inhibiting CaMKII in human pre-B ALL cells induced cell death, further supporting a role for CaMKII in leukemogenesis. This research provides novel insight into the role of Ca2+-directed signaling in lymphoid malignancy and will be useful in understanding disease development and progression.

Probiotic supplementation has sex-dependent effects on immune responses in association with the gut microbiota in community-dwelling older adults: a randomized, double-blind, placebo-controlled, multicenter trial

BACKGROUND/OBJECTIVES

Probiotics have been suggested as potent modulators of age-related disorders in immunological functions, yet little is known about sex-dependent effects of probiotic supplements. Therefore, we aimed to investigate sex-dependent effects of probiotics on profiles of the gut microbiota and peripheral immune cells in healthy older adults.

SUBJECTS/METHODS

In a randomized, double-blind, placebo-controlled, multicenter trial, healthy elderly individuals ≥ 65 yrs old were administered probiotic capsules (or placebo) for 12 wk. Gut microbiota was analyzed using 16S rRNA gene sequencing and bioinformatic analyses. Peripheral immune cells were profiled using flow cytometry for lymphocytes (natural killer, B, CD4+ T, and CD8+ T cells), dendritic cells, monocytes, and their subpopulations.

RESULTS

Compared with placebo, phylum Firmicutes was significantly reduced in the probiotic group in women, but not in men. At the genus level, sex-specific responses included reductions in the relative abundances of pro-inflammatory gut microbes, including Catabacter and unclassified_Coriobacteriales, and Burkholderia and unclassified Enterobacteriaceae, in men and women, respectively. Peripheral immune cell profiling analysis revealed that in men, probiotics significantly reduced the proportions of dendritic cells and CD14+ CD16- monocytes; however, these effects were not observed in women. In contrast, the proportion of total CD4+ T cells was significantly reduced in women in the probiotic group. Additionally, serum lipopolysaccharide-binding protein levels showed a decreasing tendency that were positively associated with changes in gut bacteria, including Catabacter (ρ = 0.678, P < 0.05) and Burkholderia (ρ = 0.673, P < 0.05) in men and women, respectively.

CONCLUSIONS

These results suggest that probiotic supplementation may reduce the incidence of inflammation-related diseases by regulating the profiles of the gut microbiota and peripheral immune cells in healthy elders in a sex-specific manner.

Heterologous Booster with BNT162b2 Induced High Specific Antibody Levels in CoronaVac Vaccinees

Immune responses after COVID-19 vaccination should be evaluated in different populations around the world. This study compared antibody responses induced by ChAdOx1 nCoV-19, CoronaVac, and BNT162b2 vaccines. Blood samples from vaccinees were collected pre- and post-vaccinations with the second and third doses. The study enrolled 78 vaccinees, of whom 62.8% were women, with the following median ages: 26 years-ChAdOx1 nCoV-19; 40 years-CoronaVac; 30 years-BNT162b2. Serum samples were quantified for anti-RBD IgG and anti-RBD IgA and anti-spike IgG by ELISA. After two vaccine doses, BNT162b2 vaccinees produced higher levels of anti-RBD IgA and IgG, and anti-spike IgG compared to ChAdOx1 nCoV-19 and CoronaVac vaccinees. The third dose booster with BNT162b2 induced higher levels of anti-RBD IgA and IgG, and anti-spike IgG in CoronaVac vaccinees. Individuals who reported a SARS-CoV-2 infection before or during the study had higher anti-RBD IgA and IgG production. In conclusion, two doses of the studied vaccines induced detectable levels of anti-RBD IgA and IgG and anti-spike IgG in vaccinees. The heterologous booster with BNT162b2 increased anti-RBD IgA and IgG and anti-spike IgG levels in CoronaVac vaccinees and anti-RBD IgA levels in ChAdOx1 nCoV-19 vaccinees. Furthermore, SARS-CoV-2 infection induced higher anti-RBD IgA and IgG levels in CoronaVac vaccinees.

Impact of age and comorbidities on SARS-CoV-2 vaccine-induced T cell immunity

BACKGROUND

Older age and chronic disease are important risk factors for developing severe COVID-19. At population level, vaccine-induced immunity substantially reduces the risk of severe COVID-19 disease and hospitalization. However, the relative impact of humoral and cellular immunity on protection from breakthrough infection and severe disease is not fully understood.

METHODS

In a study cohort of 655 primarily older study participants (median of 63 years (IQR: 51-72)), we determined serum levels of Spike IgG antibodies using a Multiantigen Serological Assay and quantified the frequency of SARS-CoV-2 Spike-specific CD4 + and CD8 + T cells using activation induced marker assay. This enabled characterization of suboptimal vaccine-induced cellular immunity. The risk factors of being a cellular hypo responder were assessed using logistic regression. Further follow-up of study participants allowed for an evaluation of the impact of T cell immunity on breakthrough infections.

RESULTS

We show reduced serological immunity and frequency of CD4 + Spike-specific T cells in the oldest age group (≥75 years) and higher Charlson Comorbidity Index (CCI) categories. Male sex, age group ≥75 years, and CCI > 0 is associated with an increased likelihood of being a cellular hypo-responder while vaccine type is a significant risk factor. Assessing breakthrough infections, no protective effect of T cell immunity is identified.

CONCLUSIONS

SARS-CoV-2 Spike-specific immune responses in both the cellular and serological compartment of the adaptive immune system increase with each vaccine dose and are progressively lower with older age and higher prevalence of comorbidities. The findings contribute to the understanding of the vaccine response in individuals with increased risk of severe COVID-19 disease and hospitalization.

Carriers of the p.P522R variant in PLCγ2 have a slightly more responsive immune system

BACKGROUND

The rs72824905 single-nucleotide polymorphism in the PLCG2 gene, encoding the p.P522R residue change in Phospholipase C gamma 2 (PLCγ2), associates with protection against several dementia subtypes and with increased likelihood of longevity. Cell lines and animal models indicated that p.P522R is a functional hypermorph. We aimed to confirm this in human circulating peripheral immune cells.

METHODS

We compared effects of p.P522R on immune system function between carriers and non-carriers (aged 59-103y), using in-depth immunophenotyping, functional B-cell and myeloid cell assays, and in vivo SARS-CoV-2 vaccination.

RESULTS

In line with expectations, p.P522R impacts immune cell function only slightly, but it does so across a wide array of immune cell types. Upon B-cell stimulation, we observed increased PLCγ2 phosphorylation and calcium release, suggesting increased B-cell sensitivity upon antigen recognition. Further, p.P522R-carriers had higher numbers of CD20++CD21-CD24+ naive B cells and IgG1+ memory B cells. In myeloid cells, normalized ROS production was higher upon PLCγ2-dependent stimulation. On classical monocytes, CD33 levels were elevated. Furthermore, carriers expressed lower levels of allergy-related FcεRI on several immune cell subsets. Nevertheless, carriers and non-carriers had similar serological responses to SARS-CoV-2 vaccination.

CONCLUSION

The immune system from p.P522R-carriers is slightly more responsive to stimulation than in non-carriers.

Immunoglobulin G glycans - Biomarkers and molecular effectors of aging

Immunoglobulin G (IgG) antibodies are post-translationally modified by the addition of complex carbohydrate molecules - glycans, which have profound effects on the IgG function, most significantly as modulators of its inflammatory capacity. Therefore, it is not surprising that the changes in IgG glycosylation pattern are associated with various physiological states and diseases, including aging and age-related diseases. Importantly, within the inflammaging concept, IgG glycans are considered not only biomarkers but one of the molecular effectors of the aging process. The exact mechanism by which they exert their function, however, remains unknown. In this review, we list and comment on, to our knowledge, all studies that examined changes in IgG glycosylation during aging in humans. We focus on the information obtained from studies on general population, but we also cover the insights obtained from studies of long-lived individuals and people with age-related diseases. We summarize the current knowledge on how levels of different IgG glycans change with age (i.e., the extent and direction of the change with age) and discuss the potential mechanisms and possible functional roles of changes in IgG glycopattern that accompany aging.

Gastric DLBCL clonal evolution as function of patient age

Diffuse large B cell lymphoma (DLBCL) is the most common type of NHL, accounting for about 40% of NHL cases, and is one of the most aggressive lymphomas. DLBCL is widespread in individuals aged more than 50 years old, with a maximum incidence in the seventh decade, but it may also occur in younger patients. DLBCL may occur in any immune system tissue, including those around the gastrointestinal tract, and even in the stomach, though gastric DLBCL has yet to be sufficiently investigated. This study aimed to understand changes in gastric Diffuse Large B cell lymphoma (gastric DLBCL) development with age. Immunoglobulin (Ig) heavy chain variable region genes were amplified from sections of nine preserved biopsies, from patients whose age varied between 25 and 89 years, sequenced and analyzed. We show first that identification of the malignant clone based on the biopsies is much less certain than was previously assumed; and second that, contrary to expectations, the repertoire of gastric B cell clones is more diverse among the elderly DLBCL patients than among the young.

Let-7 as a Promising Target in Aging and Aging-Related Diseases: A Promise or a Pledge

The abnormal regulation and expression of microRNA (miRNA) are closely related to the aging process and the occurrence and development of aging-related diseases. Lethal-7 (let-7) was discovered in Caenorhabditis elegans (C. elegans) and plays an important role in development by regulating cell fate regulators. Accumulating evidence has shown that let-7 is elevated in aging tissues and participates in multiple pathways that regulate the aging process, including affecting tissue stem cell function, body metabolism, and various aging-related diseases (ARDs). Moreover, recent studies have found that let-7 plays an important role in the senescence of B cells, suggesting that let-7 may also participate in the aging process by regulating immune function. Therefore, these studies show the diversity and complexity of let-7 expression and regulatory functions during aging. In this review, we provide a detailed overview of let-7 expression regulation as well as its role in different tissue aging and aging-related diseases, which may provide new ideas for enriching the complex expression regulation mechanism and pathobiological function of let-7 in aging and related diseases and ultimately provide help for the development of new therapeutic strategies.

Immunosenescence and Altered Vaccine Efficiency in Older Subjects: A Myth Difficult to Change

Organismal ageing is associated with many physiological changes, including differences in the immune system of most animals. These differences are often considered to be a key cause of age-associated diseases as well as decreased vaccine responses in humans. The most often cited vaccine failure is seasonal influenza, but, while it is usually the case that the efficiency of this vaccine is lower in older than younger adults, this is not always true, and the reasons for the differential responses are manifold. Undoubtedly, changes in the innate and adaptive immune response with ageing are associated with failure to respond to the influenza vaccine, but the cause is unclear. Moreover, recent advances in vaccine formulations and adjuvants, as well as in our understanding of immune changes with ageing, have contributed to the development of vaccines, such as those against herpes zoster and SARS-CoV-2, that can protect against serious disease in older adults just as well as in younger people. In the present article, we discuss the reasons why it is a myth that vaccines inevitably protect less well in older individuals, and that vaccines represent one of the most powerful means to protect the health and ensure the quality of life of older adults.

Efficacy of Disease Modifying Therapies in Progressive MS and How Immune Senescence May Explain Their Failure

The advent of disease modifying therapies (DMT) in the past two decades has been the cornerstone of successful clinical management of multiple sclerosis (MS). Despite the great strides made in reducing the relapse frequency and occurrence of new signal changes on neuroimaging in patients with relapsing remitting MS (RRMS) by approved DMT, it has been challenging to demonstrate their effectiveness in non-active secondary progressive MS (SPMS) and primary progressive MS (PPMS) disease phenotypes. The dichotomy of DMT effectiveness between RRMS and progressive MS informs on distinct pathogeneses of the different MS phenotypes. Conversely, factors that render patients with progressive MS resistant to therapy are not understood. Thus far, age has emerged as the main correlate of the transition from RRMS to SPMS. Whether it is aging and age-related factors or the underlying immune senescence that qualitatively alter immune responses as the disease transitions to SPMS, that diminish DMT effectiveness, or both, is currently not known. Here, we will discuss the role of immune senescence on different arms of the immune system, and how it may explain relative DMT resistance.

Interconnections between Inflammageing and Immunosenescence during Ageing

Acute inflammation is a physiological response to injury or infection, with a cascade of steps that ultimately lead to the recruitment of immune cells to clear invading pathogens and heal wounds. However, chronic inflammation arising from the continued presence of the initial trigger, or the dysfunction of signalling and/or effector pathways, is harmful to health. While successful ageing in older adults, including centenarians, is associated with low levels of inflammation, elevated inflammation increases the risk of poor health and death. Hence inflammation has been described as one of seven pillars of ageing. Age-associated sterile, chronic, and low-grade inflammation is commonly termed inflammageing-it is not simply a consequence of increasing chronological age, but is also a marker of biological ageing, multimorbidity, and mortality risk. While inflammageing was initially thought to be caused by "continuous antigenic load and stress", reports from the last two decades describe a much more complex phenomenon also involving cellular senescence and the ageing of the immune system. In this review, we explore some of the main sources and consequences of inflammageing in the context of immunosenescence and highlight potential interventions. In particular, we assess the contribution of cellular senescence to age-associated inflammation, identify patterns of pro- and anti-inflammatory markers characteristic of inflammageing, describe alterations in the ageing immune system that lead to elevated inflammation, and finally assess the ways that diet, exercise, and pharmacological interventions can reduce inflammageing and thus, improve later life health.

Should we vaccinate the better seroconverters or the most vulnerable? Game changing insights for COVID-19 vaccine prioritization policies

Background

With the rapid rise in COVID 19 cases incomparable to the number of vaccinations available, there has been a demand to prioritize the older age groups receiving the vaccine as they have more risk of morbidity and mortality and thus better outcome from vaccination.

Main body

Some studies showed a lower seroconversion rate in older group patients; thus, we discuss the necessity to reprioritize vaccinations to younger age groups who have better seroconversion rates, but we may face some ethical dilemma that could hinder our hypothesis. Decreased seroconversion rates in adults are attributable to immuno-senescence which involves a decrease in humoral and cellular-mediated immunity with age. Despite this fact, there remains some ethical dilemma that can hinder widespread vaccination of younger generations, the most important of which is the unknown long-term effects of COVID-19 vaccines due their fast-tracking under the pressure of the pandemic.

Short conclusion

Prioritizing children vaccination against COVID-19 seems an interesting strategy that can help in containing the pandemic. Resolving some ethical dilemma needs to be done before implementing such strategy.

Immunopathology and Immunosenescence, the Immunological Key Words of Severe COVID-19. Is There a Role for Stem Cell Transplantation?

The outcomes of Coronavirus disease-2019 (COVID-19) vary depending on the age, health status and sex of an individual, ranging from asymptomatic to lethal. From an immunologic viewpoint, the final severe lung damage observed in COVID-19 should be caused by cytokine storm, driven mainly by interleukin-6 and other pro-inflammatory cytokines. However, which immunopathogenic status precedes this "cytokine storm" and why the male older population is more severely affected, are currently unanswered questions. The aging of the immune system, i.e., immunosenescence, closely associated with a low-grade inflammatory status called "inflammageing," should play a key role. The remodeling of both innate and adaptive immune response observed with aging can partly explain the age gradient in severity and mortality of COVID-19. This review discusses how aging impacts the immune response to the virus, focusing on possible strategies to rejuvenate the immune system with stem cell-based therapies. Indeed, due to immunomodulatory and anti-inflammatory properties, multipotent mesenchymal stem cells (MSCs) are a worth-considering option against COVID-19 adverse outcomes.

Seropositivity in blood donors and pregnant women during the first year of SARS-CoV-2 transmission in Stockholm, Sweden

BACKGROUND

In Sweden, social restrictions to contain SARS-CoV-2 have primarily relied upon voluntary adherence to a set of recommendations. Strict lockdowns have not been enforced, potentially affecting viral dissemination. To understand the levels of past SARS-CoV-2 infection in the Stockholm population before the start of mass vaccinations, healthy blood donors and pregnant women (n = 5,100) were sampled at random between 14 March 2020 and 28 February 2021.

METHODS

In this cross-sectional prospective study, otherwise-healthy blood donors (n = 2,600) and pregnant women (n = 2,500) were sampled for consecutive weeks (at four intervals) throughout the study period. Sera from all participants and a cohort of historical (negative) controls (n = 595) were screened for IgG responses against stabilized trimers of the SARS-CoV-2 spike (S) glycoprotein and the smaller receptor-binding domain (RBD). As a complement to standard analytical approaches, a probabilistic (cut-off independent) Bayesian framework that assigns likelihood of past infection was used to analyse data over time.

SETTING

Healthy participant samples were randomly selected from their respective pools through Karolinska University Hospital. The study was carried out in accordance with Swedish Ethical Review Authority: registration number 2020-01807.

PARTICIPANTS

No participants were symptomatic at sampling, and blood donors were all over the age of 18. No additional metadata were available from the participants.

RESULTS

Blood donors and pregnant women showed a similar seroprevalence. After a steep rise at the start of the pandemic, the seroprevalence trajectory increased steadily in approach to the winter second wave of infections, approaching 15% of all individuals surveyed by 13 December 2020. By the end of February 2021, 19% of the population tested seropositive. Notably, 96% of seropositive healthy donors screened (n = 56) developed neutralizing antibody responses at titres comparable to or higher than those observed in clinical trials of SARS-CoV-2 spike mRNA vaccination, supporting that mild infection engenders a competent B-cell response.

CONCLUSIONS

These data indicate that in the first year since the start of community transmission, seropositivity levels in metropolitan in Stockholm had reached approximately one in five persons, providing important baseline seroprevalence information prior to the start of vaccination.

Hierarchy and control of ageing-related methylation networks

DNA methylation provides one of the most widely studied biomarkers of ageing. Since the methylation of CpG dinucleotides function as switches in cellular mechanisms, it is plausible to assume that by proper adjustment of these switches age may be tuned. Though, adjusting hundreds of CpG methylation levels coherently may never be feasible and changing just a few positions may lead to biologically unstable state. A prominent example of methylation-based age estimators is provided by Horvath's clock, based on 353 CpG dinucleotides, showing a high correlation (not necessarily causation) with chronological age across multiple tissue types. On this small subset of CpG dinucleotides we demonstrate how the adjustment of one methylation level leads to a cascade of changes at other sites. Among the studied subset, we locate the most important CpGs (and related genes) that may have a large influence on the rest of the sub-system. According to our analysis, the structure of this network is way more hierarchical compared to what one would expect based on ensembles of uncorrelated connections. Therefore, only a handful of CpGs is enough to modify the system towards a desired state. When propagation of the change over the network is taken into account, the resulting modification in the predicted age can be significantly larger compared to the effect of isolated CpG perturbations. By adjusting the most influential single CpG site and following the propagation of methylation level changes we can reach up to 5.74 years in virtual age reduction, significantly larger than without taking into account of the network control. Extending our approach to the whole methylation network may identify key nodes that have controller role in the ageing process.

Effective inactivated influenza vaccine for the elderly using a single-stranded RNA-based adjuvant

There is an unmet need for new influenza vaccine strategies that compensate for impaired vaccine responses in elderly individuals. Here, we evaluated the effectiveness of a single-stranded RNA (ssRNA) as an adjuvant to enhance the efficacy of inactivated influenza vaccine (IIV) in mouse models. Immunization with the ssRNA along with IIV reduced viral titers as well as pathological and inflammatory scores in the lungs after influenza challenge in aged mice. ssRNA induced balanced Th1/Th2 responses with an increase in IgA titers. Moreover, the ssRNA adjuvant markedly increased the frequency of influenza HA-specific T cells and IFN-γ production along with the expression of genes related to innate and adaptive immune systems that could overcome immunosenescence in aged mice. Our findings indicate that ssRNA is an efficient vaccine adjuvant that boosts cellular and humoral immunity in aged mice, demonstrating its potential as a novel adjuvant for currently available influenza virus vaccines for elderly individuals.

Proteomic signatures of inflammatory skin diseases: a focus on atopic dermatitis

Introduction: Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by cutaneous and systemic inflammation and barrier abnormalities. Over the past few decades, proteomic studies have been increasingly applied to AD research to compliment transcriptomic evaluations. Proteomic analyses helped identify new biomarkers of AD, allowing investigation of both the cutaneous AD profile and the systemic inflammation associated with the disease.Areas covered: This review discusses key studies that utilized various proteomic technologies to analyze AD skin and/or blood, which facilitated discovery of biomarkers related to pathogenesis, disease severity, systemic inflammation, and therapeutic response. Moreover, this review summarizes proteomic studies that helped define various AD endotypes/phenotypes. A literature search was conducted by querying Scopus, Google Scholar, PubMed/Medline, and Clinicaltrials.gov up to January 2021.Expert opinion: Use of proteomics in AD has allowed for identification of novel AD-related protein biomarkers. This approach continues to evolve and is becoming increasingly common for the study of AD, in conjunction with other -omics platforms, as proteomics shifts to quicker and more sensitive methods for detection of potential protein biomarkers. Although many biomarkers have been identified thus far, future larger studies are necessary to further correlate these markers with clinical parameters.

Age-related differences in the immune response could contribute to determine the spectrum of severity of COVID-19

Coronavirus disease 2019 (COVID-19), can present with a wide spectrum of severity. Elderly patients with cardiac, pulmonary and metabolic comorbidities are more likely to develop the severe manifestations of COVID-19, which are observed in less than 5% of the pediatric patients. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is able to induce an immune impairment and dysregulation, finally resulting in the massive release of inflammatory mediators, strongly contributing to the pulmonary and systemic manifestations in COVID-19. In children, the immune dysregulation following SARS-CoV-2 can also be responsible of a severe disease phenotype defined as multisystem inflammatory syndrome in children. As the immune system undergoes a complex process of maturation from birth to adult age, differences in the immune and inflammatory response could have a significant impact in determining the spectrum of severity of COVID-19. Indeed, children show a higher ability to respond to viral infections and a reduced baseline pro-inflammatory state compared with elderly patients. Age and comorbidities contribute to disease severity through immune-mediated mechanisms, since they are associated with a chronic increase of pro-inflammatory mediators, and cause an enhanced susceptibility to develop an immune dysregulation following SARS-CoV-2 infection. Also the expression of ACE2, the receptor of SARS-CoV-2, varies with age, and is linked to the immune and inflammatory response through a complex, and not completely elucidated, network. This paper reviews the peculiar immunopathogenic aspects of COVID-19, with a focus on the differences between adult and pediatric patients.

Immunosuppression Considerations for Older Kidney Transplant Recipients

PURPOSE OF REVIEW

While kidney transplantation improves the long-term survival of the majority of patients with end-stage kidney disease (ESKD), age-related immune dysfunction and associated comorbidities make older transplant recipients more susceptible to complications related to immunosuppression. In this review, we discuss appropriate management of immunosuppressive agents in older adults to minimize adverse events, avoid acute rejection, and maximize patient and graft survival.

RECENT FINDINGS

Physiological changes associated with senescence can impact drug metabolism and increase the risk of posttransplant infection and malignancy. Clinical trials assessing the safety and efficacy of immunosuppressive agents in older adults are lacking. Recent findings from U.S. transplant registry-based studies suggest that risk-adjusted death-censored graft failure is higher among older patients who received antimetabolite avoidance, mammalian target of rapamycin inhibitor (mTORi)-based, and cyclosporine-based regimens. Observational data suggest that risk-adjusted mortality may be increased in older patients who receive mTORi-based and cyclosporine-based regimens but lower in those managed with T-cell induction and maintenance steroid avoidance/withdrawal.

SUMMARY

Tailored immunosuppression management to improve patient and graft survival in older transplant recipients is an important goal of personalized medicine. Lower intensity immunosuppression, such as steroid-sparing regimens, appear beneficial whereas mTORi- and cyclosporine-based maintenance are associated with greater potential for adverse effects. Prospective clinical trials to assess the safety and efficacy of immunosuppression agents in older recipients are urgently needed.

Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease.

METHODS

In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation.

RESULTS

cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses.

CONCLUSIONS

Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.

Older adults: panoramic view on the COVID-19 vaccination

In December 2020, COVID-19 vaccination started in many countries, with which the world community hopes to stop the further spread of the current pandemic. More than 90% of sick and deceased patients belong to the category of older adults (65 years and older). This category of the population is most vulnerable to infectious diseases, so vaccination is the most effective preventive strategy, the need for which for older adults is indisputable. Here we briefly summarize information about age-related changes in the immune system and present current data on their impact on the formation of the immune response to vaccination. Older age is accompanied by the process of biological aging accompanied by involution of the immune system with increased susceptibility to infections and a decrease in the effect of immunization. Therefore, in the ongoing mass COVID-19 vaccination, the older adults are a growing public health concern. The authors provide an overview of the various types of COVID-19 vaccines approved for mass immunization of the population by the end of 2020, including older adults, as well as an overview of strategies and platforms to improve the effectiveness of vaccination of this population. In the final part, the authors propose for discussion a system for assessing the safety and monitoring the effectiveness of COVID-19 vaccines for the older adults.

Analysis of the heterogeneity of the BCR H-CDR3 repertoire in the bone marrow and spleen of 3-, 12-, and 20-month old mice

The number of central and peripheral B cells and their responsiveness are decreased in aged mice. The diversity of mice central and peripheral B cell repertoires with increasing age has not been elucidated. In this study, we demonstrated that there were significant differences in the usage of some V, D, and J genes in the BCR H-CDR3 repertoire of bone marrow B cells, spleen B cells and spleen memory B cells in 3-, 12-, and 20-month-old mice. In the productive, pseudogene, and out-of-frame sequences, bone marrow B cells had significant differences in 5′J trimming with age; peripheral spleen B cells and memory B cells had significant differences in N1 insertion, N2 insertion, P5’D insertion, and 5’D trimming with age. The BCR H-CDR3 repertoire diversity of mice bone marrow B cells, spleen B cells and spleen memory B cells decreased with increasing age. The proportion of overlap in bone marrow and spleen B cells, but not spleen memory B cells, of mice at different ages was lower at 3 months than at 12 and 20 months. This study is the first to report the homogeneity and heterogeneity of the CDR3 repertoire of central and peripheral B cells change as mice age, to further investigation of the decline and response of B cell immunity in young/middle/old-aged mice.

Use of seroprevalence to guide dengue vaccination plans for older adults in a dengue non-endemic country

A shift in dengue cases toward the adult population, accompanied by an increased risk of severe cases of dengue in the elderly, has created an important emerging issue in the past decade. To understand the level of past DENV infection among older adults after a large dengue outbreak occurred in southern Taiwan in 2015, we screened 1498 and 2603 serum samples from healthy residents aged ≥ 40 years in Kaohsiung City and Tainan City, respectively, to assess the seroprevalence of anti-DENV IgG in 2016. Seropositive samples were verified to exclude cross-reaction from Japanese encephalitis virus (JEV), using DENV/JEV-NS1 indirect IgG ELISA. We further identified viral serotypes and secondary DENV infections among positive samples in the two cities. The overall age-standardized seroprevalence of DENV-IgG among participants was 25.77% in Kaohsiung and 11.40% in Tainan, and the seroprevalence was significantly higher in older age groups of both cities. Although the percentages of secondary DENV infection in Kaohsiung and Tainan were very similar (43.09% and 44.76%, respectively), DENV-1 and DENV-2 spanned a wider age range in Kaohsiung, whereas DENV-2 was dominant in Tainan. As very few studies have obtained the serostatus of DENV infection in older adults and the elderly, this study highlights the need for further investigation into antibody status, as well as the safety and efficacy of dengue vaccination in these older populations.

B-cell capacity for differentiation changes with age

Background

Age‐related immune deficiencies are thought to be responsible for increased susceptibility to infection in older adults, with alterations in lymphocyte populations becoming more prevalent over time. The loss of humoral immunity in ageing was attributed to the diminished numbers of B cells and the reduced ability to generate immunoglobulin.

Aims

To compare the intrinsic B‐cell capacity for differentiation into mature plasma cells (PCs), between young and old donors, using in vitro assays, providing either effective T‐cell help or activation via TLR engagement.

Methods

B cells were isolated from healthy individuals, in younger (30–38 years) and older (60–64 years) donors. An in vitro model system of B‐cell differentiation was used, analysing 5 differentiation markers by flow cytometry, under T‐dependent (TD: CD40/BCR stimulation) or T‐independent (TI: TLR7/BCR activation) conditions. Antibody secretion was measured by ELISA and gene expression using qPCR.

Results

TI and TD differentiation resulted in effective proliferation of B cells followed by their differentiation into PC. B‐cell‐executed TI differentiation was faster, all differentiation marker and genes being expressed earlier than under TD differentiation (day 6), although generating less viable cells and lower antibody levels (day 13). Age‐related differences in B‐cell capacity for differentiation were minimal in TD differentiation. In contrast, in TI differentiation age significantly affected proliferation, viability, differentiation, antibody secretion and gene expression, older donors being more efficient.

Conclusion

Altogether, B‐cell differentiation into PC appeared similar between age groups when provided with T‐cell help, in contrast to TI differentiation, where multiple age‐related changes suggest better capacities in older donors. These new findings may help explain the emergence of autoantibodies in ageing.

Using Domain Based Latent Personal Analysis of B Cell Clone Diversity Patterns to Identify Novel Relationships Between the B Cell Clone Populations in Different Tissues

The B cell population is highly diverse and very skewed. It is divided into clones (B cells with a common mother cell). It is thought that each clone represents an initial B cell receptor specificity. A few clones are very abundant, comprised of hundreds or thousands of B cells while the majority have only a few cells per clone. We suggest a novel method - domain-based latent personal analysis (LPA), a method for spectral exploration of entities in a domain, which can be used to find the spectral spread of sub repertoires within a person. LPA defines a domain-based spectral signature for each sub repertoire. LPA signatures consist of the elements, in our case - the clones, that most differentiate the sub repertoire from the person’s abundance of clones. They include both positive elements, which describe overabundant clones, and negative elements that describe missing clones. The signatures can also be used to compare the sub repertoires they represent to each other. Applying LPA to compare the repertoires found in different tissues, we reiterated previous findings that showed that gut and blood tissues have separate repertoires. We further identify a third branch of clonal patterns typical of the lymphatic organs (Spleen, MLN, and bone marrow) separated from the other two categories. We developed a python version of LPA analysis that can easily be applied to compare clonal distributions - https://github.com/ScanLab-ossi/LPA. It could also be easily adapted to study other skewed sequence populations used in the analysis of B cell receptor populations, for instance, k-mers and V gene usage. These analysis types should allow for inter and intra-repertoire comparisons of diversity, which could revolutionize the way we understand repertoire changes and diversity.

Combination of the Probiotics Lacticaseibacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis, BB-12 Has Limited Effect on Biomarkers of Immunity and Inflammation in Older People Resident in Care Homes: Results From the Probiotics to Reduce Infections iN CarE home reSidentS Randomized, Controlled Trial

Aging is associated with a decline in many components of the immune system (immunosenescence). Probiotics may improve the immune response in older people. The objective was to determine the effect of the combination of two probiotic organisms [Lacticaseibacillus (previously known as Lactobacillus) rhamnosus GG (LGG) and Bifidobacterium animalis subsp. lactis, BB-12 (BB-12)] on a range of immune biomarkers measured in the blood of older people resident in care homes in the UK. In a randomized controlled trial, older people [aged 67-97 (mean 86) years] resident in care homes received the combination of LGG+BB-12 (1.3-1.6 × 10⁹ CFU per day) or placebo for up to 12 months. Full blood count, blood immune cell phenotypes, plasma immune mediator concentrations, phagocytosis, and blood culture responses to immune stimulation were all measured. Response to seasonal influenza vaccination was measured in a subset of participants. Paired samples (i.e., before and after intervention) were available for 30 participants per group. LGG and BB-12 were more likely to be present in feces in the probiotic group and were present at higher numbers. There was no significant effect of the probiotics on components of the full blood count, blood immune cell phenotypes, plasma immune mediator concentrations, phagocytosis by neutrophils and monocytes, and blood culture responses to immune stimulation. There was an indication that the probiotics improved the response to seasonal influenza vaccination with significantly (p = 0.04) higher seroconversion to the A/Michigan/2015 vaccine strain in the probiotic group than in the placebo group (47 vs. 15%).

Age-Related Lymphocyte Output During Disease-Modifying Therapies for Multiple Sclerosis

BACKGROUND

Patients with multiple sclerosis exhibit the same qualitative and quantitative changes in immune system cells observed in aging. In the last 20 years, multiple sclerosis patients have shown an increase in life expectancy and average age, but clinical trial inclusion criteria typically exclude patients over the age of 55 years. Therefore, disease-modifying therapies are likely administered to patients older than those enrolled in clinical trials.

OBJECTIVE

In order to investigate whether disease-modifying therapies for multiple sclerosis induce modifications to the immune system that may have (super)additive effects resulting in an acceleration of immunosenescence, we quantified the number of T-cell receptor excision circles (TRECs) and K-deleting recombination excision circles (KRECs). These molecules are contained in new T and B lymphocytes released by the thymus and bone marrow and are considered molecular age-related markers.

METHODS

The markers of aging were measured by a multiplex quantitative real-time PCR assay in 122 patients who had started therapy with interferon-beta (IFN-β), fingolimod, alemtuzumab, or natalizumab. Samples were obtained before the therapy and at 6 and 12 months of treatment. Comparisons between the variables were performed by a non-parametric statistical analysis.

RESULTS

In therapy-naive patients, a significant and direct correlation was found between a lower number of newly produced T and B cells and older age. Although disease-modifying therapies induced different changes (both increases and decreases) in the production of new T and B lymphocytes, 12 months of therapy with IFN-β or natalizumab did not affect the correlations found at baseline between the release of lymphocytes containing TRECs or KRECs and age. On the contrary, in patients treated with alemtuzumab, both correlations were lost, while in fingolimod-treated patients, only the correlation between TRECs and age disappeared.

CONCLUSIONS

This observational study indicated that different age-related changes of the new T and B lymphocyte production could be one of the reasons for the emergence, in the real-world setting, of adverse events not otherwise observed in clinical trials; thus, caution is advised when choosing disease-modifying therapies for multiple sclerosis patients.

Exercise reduces metabolic burden while altering the immune system in aged mice

Although several evidence has suggested the impact of exercise on the prevention of aging phenotypes, few studies have been conducted on the mechanism by which exercise alters the immune-cell profile, thereby improving metabolism in senile obesity. In this study, we confirmed that 4-week treadmill exercise sufficiently improved metabolic function, including increased lean mass and decreased fat mass, in 88-week-old mice. The expression level of the senescence marker p16 in the white adipose tissue (WAT) was decreased after 4-weeks of exercise. Exercise induced changes in the profiles of immune-cell subsets, including natural killer (NK) cells, central memory CD8⁺ T cells, eosinophils, and neutrophils, in the stromal vascular fraction of WAT. In addition, it has been shown through transcriptome analysis of WAT that exercise can activate pathways involved in the interaction between WAT and immune cells, in particular NK cells, in aged mice. These results suggest that exercise has a profound effect on changes in immune-cell distribution and senescent-cell scavenging in WAT of aged mice, eventually affecting overall energy metabolism toward a more youthful state.

Organoid Polymer Functionality and Mode of Klebsiella Pneumoniae Membrane Antigen Presentation Regulates Ex Vivo Germinal Center Epigenetics in Young and Aged B Cells

Antibiotic-resistant bacteria are a major global health threat that continues to rise due to a lack of effective vaccines. Of concern are Klebsiella pneumoniae that fail to induce in vivo germinal center B cell responses, which facilitate antibody production to fight infection. Immunotherapies using antibodies targeting antibiotic-resistant bacteria are emerging as promising alternatives, however, they cannot be efficiently derived ex vivo, necessitating the need for immune technologies to develop therapeutics. Here, PEG-based immune organoids were developed to elucidate the effects of polymer end-point chemistry, integrin ligands, and mode of K. pneumoniae antigen presentation on germinal center-like B cell phenotype and epigenetics, to better define the lymph node microenvironment factors regulating ex vivo germinal center dynamics. Notably, PEG vinyl sulfone or acrylate failed to sustain primary immune cells, but functionalization with maleimide (PEG-4MAL) led to B cell expansion and germinal center-like induction. RNA sequencing analysis of lymph node stromal and germinal center B cells showed niche associated heterogeneity of integrin-related genes. Incorporation of niche-mimicking peptides revealed that collagen-1 promoted germinal center-like dynamics and epigenetics. PEG-4MAL organoids elucidated the impact of K. pneumoniae outer membrane-embedded protein antigen versus soluble antigen presentation on germinal centers and preserved the response across young and aged mice.

Immunosenescence: a key player in cancer development

Immunosenescence is a process of immune dysfunction that occurs with age and includes remodeling of lymphoid organs, leading to changes in the immune function of the elderly, which is closely related to the development of infections, autoimmune diseases, and malignant tumors. T cell-output decline is an important feature of immunosenescence as well as the production of senescence-associated secretory phenotype, increased glycolysis, and reactive oxygen species. Senescent T cells exhibit abnormal phenotypes, including downregulation of CD27, CD28, and upregulation of CD57, killer cell lectin-like receptor subfamily G, Tim-3, Tight, and cytotoxic T-lymphocyte-associated protein 4, which are tightly related to malignant tumors. The role of immunosenescence in tumors is sophisticated: the many factors involved include cAMP, glucose competition, and oncogenic stress in the tumor microenvironment, which can induce the senescence of T cells, macrophages, natural killer cells, and dendritic cells. Accordingly, these senescent immune cells could also affect tumor progression. In addition, the effect of immunosenescence on the response to immune checkpoint blocking antibody therapy so far is ambiguous due to the low participation of elderly cancer patients in clinical trials. Furthermore, many other senescence-related interventions could be possible with genetic and pharmacological methods, including mTOR inhibition, interleukin-7 recombination, and NAD⁺ activation. Overall, this review aims to highlight the characteristics of immunosenescence and its impact on malignant tumors and immunotherapy, especially the future directions of tumor treatment through senescence-focused strategies.

Immunity to acute virus infections with advanced age

New infections in general, and new viral infections amongst them, represent a serious challenge to an older organism. This review discusses the age-related alterations in responsiveness to infection from the standpoint of virus:host relationship and the host physiological whole-organism and specific immune response to the virus. Changes with age in the innate and adaptive immune system homeostasis and function are reviewed briefly. This is followed by a review of specific alterations and defects in the response of older organisms (chiefly mice and humans) to acute (particularly emerging and re-emerging) viral infections, with a very brief summary of the response to latent persistent infections. Finally, we provide a brief summary of the perspectives for possible interventions to enhance antiviral immunity.

Role of Peripheral Immune Cells-Mediated Inflammation on the Process of Neurodegenerative Diseases

Neurodegenerative diseases are characterized by progressive loss of selectively vulnerable neuronal populations, which contrasts with selectively static loss of neurons due to toxic or metabolic disorders. The mechanisms underlying their progressive nature remain unknown. To date, a timely and well-controlled peripheral inflammatory reaction is verified to be essential for neurodegenerative diseases remission. The influence of peripheral inflammation on the central nervous system is closely related to immune cells activation in peripheral blood. The immune cells activation participated in the uncontrolled and prolonged inflammation that drives the chronic progression of neurodegenerative diseases. Thus, the dynamic modulation of this peripheral inflammatory reaction by interrupting the vicious cycle might become a disease-modifying therapeutic strategy for neurodegenerative diseases. This review focused on the role of peripheral immune cells on the pathological progression of neurodegenerative diseases.

Immunogenicity of H5N1 influenza vaccines in elderly adults: a systematic review and meta-analysis

Several different vaccines have been produced for human use to prevent the highly pathogenic H5N1 influenza. Some studies reported that the clinical effectiveness of influenza vaccines in older adults may be lower than in younger adults. In this study, a meta-analysis of the immunogenicity of H5N1 influenza vaccines in elderly adults was performed. Database search was conducted in EMBASE, PubMed, the Cochrane Library, Chinese VIP, Wanfang and CBM. A total of 3951 elderly adults from 10 articles were included in the meta-analysis. Compared to a single dose, two doses of H5N1 vaccines resulted in the higher seroconversion and seroprotection. For all groups treated with adjuvanted vaccines, there were significant increases (1.55- to 2.16-fold) in the seroconversion rates (SCRs) and seroprotection rates (SPRs) after two immunizations. Oil-in-water emulsion (OE)-adjuvanted 7.5 μg vaccine caused higher antibody responses than 3.75 μg of vaccine (SCR: risk ratio (RR) = 1.26 (1.19, 1.33); SPR: RR = 1.25 (1.14, 1.36)). Elderly adults exhibited slightly lower antibody responses only when given 7.5 μg of OE-adjuvanted vaccine (SCR: RR = 1.06 (1.01, 1.11)) than younger adults. After treatment with the 7.5 μg of OE-adjuvanted vaccines, the most commonly reported adverse events were injection site pain, swelling and erythema, with the incidence of 32%, 3% and 2%, respectively, and no serious adverse events were found. These data demonstrate that two doses of 7.5 µg of OE-adjuvanted H5N1 vaccine are well tolerated and induce a robust antibody response in elderly adults.

The possible pathophysiology mechanism of cytokine storm in elderly adults with COVID-19 infection: the contribution of "inflame-aging"

Purpose

Novel Coronavirus disease 2019 (COVID-19), is an acute respiratory distress syndrome (ARDS), which is emerged in Wuhan, and recently become worldwide pandemic. Strangely, ample evidences have been shown that the severity of COVID-19 infections varies widely from children (asymptomatic), adults (mild infection), as well as elderly adults (deadly critical). It has proven that COVID-19 infection in some elderly critical adults leads to a cytokine storm, which is characterized by severe systemic elevation of several pro-inflammatory cytokines. Then, a cytokine storm can induce edematous, ARDS, pneumonia, as well as multiple organ failure in aged patients. It is far from clear till now why cytokine storm induces in only COVID-19 elderly patients, and not in young patients. However, it seems that aging is associated with mild elevated levels of local and systemic pro-inflammatory cytokines, which is characterized by “inflamm-aging”. It is highly likely that “inflamm-aging” is correlated to increased risk of a cytokine storm in some critical elderly patients with COVID-19 infection.

Methods

A systematic search in the literature was performed in PubMed, Scopus, Embase, Cochrane Library, Web of Science, as well as Google Scholar pre-print database using all available MeSH terms for COVID-19, Coronavirus, SARS-CoV-2, senescent cell, cytokine storm, inflame-aging, ACE2 receptor, autophagy, and Vitamin D. Electronic database searches combined and duplicates were removed.

Results

The aim of the present review was to summarize experimental data and clinical observations that linked the pathophysiology mechanisms of “inflamm-aging”, mild-grade inflammation, and cytokine storm in some elderly adults with severe COVID-19 infection.

T Cell-Expressed microRNA-155 Reduces Lifespan in a Mouse Model of Age-Related Chronic Inflammation

Aging-related chronic inflammation is a risk factor for many human disorders through incompletely understood mechanisms. Aged mice deficient in microRNA (miRNA/miR)-146a succumb to life-shortening chronic inflammation. In this study, we report that miR-155 in T cells contributes to shortened lifespan of miR-146a-/- mice. Using single-cell RNA sequencing and flow cytometry, we found that miR-155 promotes the activation of effector T cell populations, including T follicular helper cells, and increases germinal center B cells and autoantibodies in mice aged over 15 months. Mechanistically, aerobic glycolysis genes are elevated in T cells during aging, and upon deletion of miR-146a, in a T cell miR-155-dependent manner. Finally, skewing T cell metabolism toward aerobic glycolysis by deleting mitochondrial pyruvate carrier recapitulates age-dependent T cell phenotypes observed in miR-146a-/- mice, revealing the sufficiency of metabolic reprogramming to influence immune cell functions during aging. Altogether, these data indicate that T cell-specific miRNAs play pivotal roles in regulating lifespan through their influences on inflammaging.

Lymphocyte Subgroups and KREC Numbers in Common Variable Immunodeficiency: A Single Center Study

Common variable immunodeficiency (CVID) results in defective B cell differentiation and impaired antibody production and is the most common symptomatic primary immunodeficiency. Our aim was to evaluate the correlation among B cell subgroups, κ-deleting recombination excision circle (KREC) copy numbers, and clinical and immunological data of the patients with CVID, and evaluate the patients according to classifications currently available to define the role of KREC copy numbers in the diagnosis of CVID. KREC analysis was performed using a quantitative real-time polymerase chain reaction assay, and B cell subgroups were measured by flow cytometry. The median age of the patients (n = 30) was 25 (6-69) years. Parental consanguinity ratio was 33%. The median age at diagnosis was 15 (4-59), and follow-up period was 6 (1-37) years. CD19⁺ and CD4⁺ cell counts at the time of diagnosis were low in 66.7% and 46.7% of the patients, respectively. CD19⁺ cell counts were positively correlated with KREC copy numbers in patients and healthy controls. CD19⁺ cell counts and KREC copy numbers were significantly reduced in CVID patients compared to healthy controls as expected. KRECs are quantitative markers for B cell defects. We found low CD4⁺ cell numbers, recent thymic emigrants, and lymphopenia in some of the patients at diagnosis, which reminds the heterogeneity of CVID's etiology. In this study, a positive correlation was shown between CD19⁺ cell counts and KREC copy numbers. Low KREC copy numbers indicated B cell deficiency; however, high KREC copy numbers were not sufficient to rule out CVID.

Decreased B1 and B2 Lymphocytes Are Associated With Mortality in Elderly Patients With Chronic Kidney Diseases

Aim: Loss of renal function is associated with immune deficiency; however, few studies have addressed the role of B lymphocytes in elderly patients with chronic kidney disease (CKD). In this study, we examined the distribution and the relationship of the B lymphocyte subpopulation with clinical outcomes in elderly CKD patients. Methods: In this study, a total of 380 patients (312 CKD patients and 68 non-CKD controls) were recruited. Venous blood samples were analyzed by flow cytometry to determine the following B cell subsets: total B cells (CD19+), innate B1 cells (CD19+CD5+), and conventional B2 cells (CD19+CD5-). Correlations between the B cell subsets with clinical features and patient prognosis were analyzed. Results: A total of 380 patients (mean age 82.29 ± 6.22 years, 76.3% male) were included. The median follow-up time was 37.0 months (range, 1-109 months); 109 (28.7%) patients died. The main causes of death were infections (59.6%) and cardiovascular diseases (22.9%). Correlation analysis showed that levels of serum creatinine (SCr), blood urea nitrogen (BUN), and CKD were negatively associated with B1 cells. However, lymphocytes, T lymphocytes, and estimated glomerular filtration rate (eGFR) were positively correlated with B1 cells (all P < 0.05). B2 cells were negatively associated with age, SCr, cystatin C, BUN, and CKD, and were positively correlated with hemoglobin, lymphocytes, T lymphocytes, NK cells, and eGFR (all P < 0.05). Patient survival was significantly better in patients with B cells > 0.05 × 10⁹/L, B1 cells > 0.02 × 10⁹/L, and B2 cells > 0.04 × 10⁹/L. Multivariate Cox regression analysis showed that B1 cells > 0.02 × 10⁹/L [hazard ratio (HR) = 0.502, 95% confidence interval (CI): 0.297-0.851, P = 0.010] and B2 cells > 0.04 × 10⁹/L (HR = 0.536, 95% CI: 0.319-0.901, P = 0.019) were independent protective factors for all-cause mortality. Conclusions: Our results showed that B1 and B2 cells exhibited a significantly negative correlation with the progression of CKD in elderly patients. Moreover, B1 and B2 cells were independent prognostic factors for survival, which indicates that the decrease in B cells may be associated with the progression of kidney diseases.

A Functional Assay to Assess Toxicity During Murine B Cell Development In Vitro

B lymphocytes, or B cells, are important players in immunity that produce antigen-specific immunoglobulins. As a result, they are involved in various immune-linked pathologies. To better understand, prevent, or treat B cell-associated disease and immunotoxicity, we developed an in vitro assay to model early murine B cell differentiation within the bone marrow. This model uses sorted B cell precursors cultured on a supporting stromal cell layer, which over time acquire markers of further differentiated B cells, such as surface antigens and rearranged immunoglobulin light chain. Importantly, we utilized our in vitro model to validate our previous observations that xenobiotics, such as tungsten and organotins, alter B cell development in vivo. Furthermore, gene expression can be modulated in this model using retroviral transduction, making it amenable to investigating signaling pathways involved in disruption of B cell differentiation. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Assessment of early B lymphocyte differentiation in vitro Support Protocol: Isolation of murine bone marrow Alternate Protocol 1: Addition of recombinant interleukin-7 Alternate Protocol 2: Genetic manipulation via retroviral transduction.

Plasma Cells, the Next Generation: Beyond Antibody Secretion

Plasma cells (PCs) represent the terminal differentiation step of mature B lymphocytes. These cells are most recognizable for their extended lifespan as well as their ability to secrete large amounts of antibodies (Abs) thus positioning this cell type as a key component of humoral immunity. However, it is now appreciated that PCs can have far reaching effects on pathologic as well as non-pathologic processes independent of Ab secretion. This is highlighted by recent studies showing that PCs function as key regulators of processes such as hematopoiesis as well as neuro-inflammation. In part, PCs accomplish this by integrating extrinsic signals from their environment which dictate their downstream functionality. Here we summarize the current understanding of PC biology focusing on their ever-growing functional repertoire independent of Ab production. Furthermore, we discuss potential applications of PC immunotherapy and its implementation for translational benefit.

Flow Cytometry as a Diagnostic Tool in Primary and Secondary Immune Deficiencies

Flow cytometry is an incredibly powerful diagnostic tool in the evaluation of primary and secondary immune deficiencies. Assay design and setup involves a methodological consideration of specimen collection, marker and fluorochrome selection, antibody titration, instrumentation, compensation, gating, reference range development, and cross validation. Commonly used analyses for lymphocytes are the lymphocyte subset, T-cell subset, B-cell and T-cell naive/memory, double-negative T-cell, and plasmablast panels. Flow cytometry has direct clinical applicability to the workup of severe forms of primary immune deficiency disorders and is used diagnostically and for therapeutic monitoring in the context of secondary immune deficiency disorders.

The Impact of the Microbiome on Immunosenescence

Human microbiome investigations now provide evidence that changes in the microbiome over time and their interaction with the immune, endocrine, and nervous systems are associated with a wide array of disorders. Human immunological studies typically absent a microbiome consideration in their investigations. An area of recent exploration is the role of the microbiome as a critical partner in the development and function of the human immune system in aging. It is well known that immunologic maturation is influenced by a lifetime of interactions of the host with its companion microbiome. It is generally not well recognized that intestinal microbes play an essential role in the development and expansion of gut mucosal and systemic immune function. Gut microbial communities of elderly people have different composition and behavior compared to healthy younger adults. Comorbidities associated with microbial pathogens and an aberrant immune system tend to increase with aging. This review underscores the impact of the human-microbiome interface on the development and function of the immune system and on immunosenescence. These changes have important implications regarding health and health system utilization in the elderly population.

Increased cardiovascular and atherosclerosis markers in blood of older patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is associated with increased systemic inflammation and cardiovascular risk. Although previous studies have found increased inflammatory proteins in the blood of patients with AD, detailed comparison among patients with AD of different ages is unavailable.

OBJECTIVE

To characterize the blood proteomic signature of patients with AD as a function of age.

METHODS

We used the OLINK high-throughput proteomic assay to measure serum inflammatory and cardiovascular risk proteins in 71 patients with moderate to severe AD from 3 age groups (18-40 years old [n = 26], 41-60 years old [n = 24], and >60 years old [n = 21]) compared with 37 age-matched controls. Total and allergen-specific serum IgEs were also measured.

RESULTS

When we compared patients with AD from 3 different age groups with their respective controls, we identified a total of 172 differentially expressed proteins. T_H2 chemokines (CCL13, CCL17) were consistently elevated in patients with AD across all ages (P < .05), whereas T_H1 (CXCL10) and T_H17 (KYNU, CCL20) markers incrementally increased with age in both patients with AD and healthy subjects. Elderly patients with AD (>60 years old) exhibited striking upregulation of key proinflammatory proteins, including markers of atherosclerosis (CCL4, CCL7, SORT1), cardiovascular risk (GDF15, MPO, ST2), cell adhesion (CDH3), and apoptosis (FAS; all P < .05) compared with younger patients with AD and age-matched controls. We also found that total and allergen-specific serum IgEs decreased significantly with age in patients with AD (P < .05).

CONCLUSION

Elderly patients with AD had increased levels of systemic inflammatory markers, including those associated with cardiovascular and atherosclerosis risk, which may explain their increased incidence of cardiovascular disease. This finding suggests that older patients with AD may benefit from cardiovascular disease screening and prevention.

Community-acquired pneumonia in patients with bacterial meningitis: a prospective nationwide cohort study

OBJECTIVE

Pneumonia is considered a focus of infection in patients presenting with community-acquired bacterial meningitis but the impact on disease course is unclear. The aim was to study presenting characteristics, clinical course and outcome of meningitis patients with co-existing pneumonia on admission.

METHODS

We evaluated adult patients with community-acquired bacterial meningitis with pneumonia on admission in a nationwide, prospective cohort performed from March 2006 to June 2017. We performed logistic regression analysis to identify clinical characteristics predictive of pneumonia on admission, and to quantify the effect of pneumonia on outcome.

RESULTS

Pneumonia was diagnosed on admission in 315 of 1852 (17%) bacterial meningitis episodes and confirmed by chest X-ray in 256 of 308 (83%) episodes. Streptococcus pneumoniae was the causative organism in 256 of 315 episodes (81%). Pneumonia on admission was associated with advanced age (OR 1.03 per year increase, 95% CI 1.02-1.04, p < 0.001), alcoholism (OR 1.96, 95% CI 1.23-3.14, p 0.004), cancer (OR 1.54, 95% CI 1.12-2.13, p 0.008), absence of otitis or sinusitis (OR 0.44, 95% CI 0.32-0.59, p < 0.001) and S. pneumoniae (OR 2.14, 95% CI 1.55-2.95, p < 0.001) in the multivariate analysis. An unfavourable outcome defined as a score of 1-4 on the Glasgow Outcome Scale was observed in 172 (55%) episodes and 87 patients (28%) died. Pneumonia on admission was independently associated with unfavourable outcome and mortality in the multivariate analysis (OR 1.48, 95% CI 1.12-1.96; p 0.005).

CONCLUSION

Pneumonia on admission in bacterial meningitis is a frequent coexisting infection and is independently associated with unfavourable outcome and mortality.

The presence of CLL-associated stereotypic B cell receptors in the normal BCR repertoire from healthy individuals increases with age

Background

Aging is known to induce immunosenescence, resulting in alterations in both the innate and adaptive immune system. Here we evaluated the effects of aging on B cell subsets in peripheral blood of 155 immunologically healthy individuals in four age categories (range 20-95y) via multi-parameter flow cytometry. Furthermore, we studied the naive and antigen-experienced B cell receptor (BCR) repertoire of different age groups and compared it to the clonal BCR repertoire of chronic lymphocytic leukemia (CLL), a disease typically presenting in elderly individuals.

Results

Total numbers and relative frequencies of B cells were found to decline upon aging, with reductions in transitional B cells, memory cell types, and plasma blasts in the 70 + y group. The BCR repertoire of naive mature B cells and antigen-experienced B cells did not clearly alter until age 70y. Clear changes in IGHV gene usage were observed in naive mature B cells of 70 + y individuals, with a transitional pattern in the 50-70y group. IGHV gene usage of naive mature B cells of the 50-70y, but not the 70 + y, age group resembled that of both younger (50-70y) and older (70 + y) CLL patients. Additionally, CLL-associated stereotypic BCR were found as part of the healthy control BCR repertoire, with an age-associated increase in frequency of several stereotypic BCR (particularly subsets #2 and #5).

Conclusion

Composition of the peripheral B cell compartment changes with ageing, with clear reductions in non-switched and CD27 + IgG+ switched memory B cells and plasma blasts in especially the 70 + y group. The BCR repertoire is relatively stable until 70y, whereafter differences in IGHV gene usage are seen. Upon ageing, an increasing trend in the occurrence of particular CLL-associated stereotypic BCR is observed.

Electronic supplementary material

The online version of this article (10.1186/s12979-019-0163-x) contains supplementary material, which is available to authorized users.