Accumulation of memory T cells from childhood to old age: Central and effector memory cells in CD4+ versus effector memory and terminally differentiated memory cells in CD8+ compartment

[Age-related changes in the immune system and cognitive disorders in vascular dementia and Alzheimer's disease]

The immune mechanisms of cognitive impairment are considered. Various causal relationships of the development of immune and neurodegenerative disorders, including vascular dementia (VD) and Alzheimer's disease (AD), are analyzed. It has been shown that age-related adaptive restructuring of immunity leads to the fact that lymphocytic immunity as a whole begins to work in an intermediate metastable state. The dominant role of immune factors in the development of VD and AD is highlighted. It is concluded that the pathogenesis of neurodegenerative diseases is associated with a decrease in antibody activity. The number of cytokines in aging animals is significantly reduced which leads to a decrease in the level of the immune response of the cell.

Normal Aging and Its Role in Cancer Metastasis

Metastasis is the most common cause of death, with treatments failing to provide a durable response. Aging is a key prognostic factor in many cancers. Emerging data suggest that normal age-related changes in the tumor microenvironment can contribute to metastatic progression. These changes encompass secreted factors, biophysical changes, and changes in both stromal and immune cell populations. These data also highlight the importance of conducting studies in preclinical models of appropriate age. Ultimately, therapies may also need to be tailored to reflect patient age, as markers of metastatic disease differ in young and aged populations. In this review, we will discuss some of the changes that occur during aging that increase the metastatic capacity of tumor cells.

The "Virtual Digital Twins" Concept in Precision Nutrition

Nutritional and lifestyle changes remain at the core of healthy aging and disease prevention. Accumulating evidence underscores the impact of genetic, metabolic, and host gut microbial factors on individual responses to nutrients, paving the way for the stratification of nutritional guidelines. However, technological advances that incorporate biological, nutritional, lifestyle, and health data at an unprecedented scale and depth conceptualize a future where preventative dietary interventions will exceed stratification and will be highly individualized. We herein discuss how genetic information combined with longitudinal metabolomic, immune, behavioral, and gut microbial parameters, and bioclinical variables could define a digital replica of oneself, a "virtual digital twin," which could serve to guide nutrition in a personalized manner. Such a model may revolutionize the management of obesity and its comorbidities, and provide a pillar for healthy aging.

Children From the Age of Three Show a Developmental Switch in T-Cell Differentiation

Every sixth child suffers from hypertrophy of the adenoid, a secondary lymphoid organ, at least once in childhood. Little is known about the impact of pathogen-provocation vs. developmental impact on T-cell responses after 1 year of age. Therefore, developmental and infection-driven influences on the formation of T-cell-compartments and -multifunctionality in adenoids were analyzed taking into account patient's history of age and inflammatory processes. Here, we show that in adenoids of 102 infants and children similar frequencies of naïve, effector, and memory T-cells were accumulated, whereby history of suffering from subsequent infection symptoms resulted in lower frequencies of CD4⁺ and CD8⁺ T-cells co-expressing several cytokines. While patients suffering from sole nasal obstruction had balanced Th1- and Th17-compartments, Th1 dominated in patients with concomitant upper airway infections. In addition, analysis of cytokine co-expressing CD4⁺ and CD8⁺ T-cells showed that children at the age of three or older differed significantly from those being 1- or 2-years old, implicating a developmental switch in T-cell differentiation at that age. Yet, dissecting age and infectious history of the patients revealed that while CD8⁺ T-cell differentiation seems to be triggered by development, CD4⁺ T-cell functionality is partly impaired by infections. However, this functionality recovers by the age of 3 years. Thus, 3 years of age seems to be a critical period in an infant's life to develop robust T-cell compartments of higher quality. These findings identify important areas for future research and distinguish an age period in early childhood when to consider adjusting the choice of treatment of infections.

A novel humanized mouse model to study the function of human cutaneous memory T cells in vivo in human skin

Human skin contains a population of memory T cells that supports tissue homeostasis and provides protective immunity. The study of human memory T cells is often restricted to in vitro studies and to human PBMC serving as primary cell source. Because the tissue environment impacts the phenotype and function of memory T cells, it is crucial to study these cells within their tissue. Here we utilized immunodeficient NOD-scid IL2rγ^null (NSG) mice that carried in vivo-generated engineered human skin (ES). ES was generated from human keratinocytes and fibroblasts and was initially devoid of skin-resident immune cells. Upon adoptive transfer of human PBMC, this reductionist system allowed us to study human T cell recruitment from a circulating pool of T cells into non-inflamed human skin in vivo. Circulating human memory T cells preferentially infiltrated ES and showed diverse functional profiles of T cells found in fresh human skin. The chemokine and cytokine microenvironment of ES closely resembled that of non-inflamed human skin. Upon entering the ES T cells assumed a resident memory T cell-like phenotype in the absence of infection, and a proportion of these cutaneous T cells can be locally activated upon injection of monocyte derived dendritic cells (moDCs) that presented Candida albicans. Interestingly, we found that CD69⁺ memory T cells produced higher levels of effector cytokines in response to Candida albicans, compared to CD69^- T cells. Overall, this model has broad utility in many areas of human skin immunology research, including the study of immune-mediated skin diseases.

In-depth immune cellular profiling reveals sex-specific associations with frailty

Background

With advancing age, the composition of leukocyte subpopulations in peripheral blood is known to change, but how this change differs between men and women and how it relates to frailty is poorly understood. Our aim in this exploratory study was to investigate whether frailty is associated with changes in immune cell subpopulations and whether this differs between men and women. Therefore, we performed in-depth immune cellular profiling by enumerating a total of 37 subpopulations of T cells, B cells, NK cells, monocytes, and neutrophils in peripheral blood of 289 elderly people between 60-87 years of age. Associations between frailty and each immune cell subpopulation were tested separately in men and women and were adjusted for age and CMV serostatus. In addition, a random forest algorithm was used to predict a participant’s frailty score based on enumeration of immune cell subpopulations.

Results

In the association study, frailty was found to be associated with increased numbers of neutrophils in both men and in women. Frailer women, but not men, showed higher numbers of total and CD16^- monocytes, and lower numbers of both CD56⁺ T cells and late differentiated CD4⁺ TemRA cells. The random forest algorithm confirmed all the findings of the association studies in men and women. In men, the predictive accuracy of the algorithm was too low (5.5%) to warrant additional conclusions on top of the ones derived from the association study. In women however, the predictive accuracy was higher (23.1%), additionally revealing that total T cell numbers and total lymphocyte numbers also contribute in predicting frailty.

Conclusions

In-depth immune cellular profiling revealed consistent associations of frailty with elevated numbers of myeloid cell subpopulations in both men and women. Furthermore, additional associations were found between frailty and lower numbers of some T cell subpopulations, in women only. Thus, our study indicates sex-specific associations of immune subpopulations with frailty. We hope that our study will prompt further investigation into the sex-specific immune mechanisms associated with the development of frailty.

Innate Immune Cells and Their Contribution to T-Cell-Based Immunotherapy

In recent years, immunotherapy has become the most promising therapy for a variety of cancer types. The development of immune checkpoint blockade (ICB) therapies, the adoptive transfer of tumor-specific T cells (adoptive cell therapy (ACT)) or the generation of T cells engineered with chimeric antigen receptors (CAR) have been successfully applied to elicit durable immunological responses in cancer patients. However, not all the patients respond to these therapies, leaving a consistent gap of therapeutic improvement that still needs to be filled. The innate immune components of the tumor microenvironment play a pivotal role in the activation and modulation of the adaptive immune response against the tumor. Indeed, several efforts are made to develop strategies aimed to harness innate immune cells in the context of cancer immunotherapy. In this review, we describe the contribution of innate immune cells in T-cell-based cancer immunotherapy and the therapeutic approaches implemented to broaden the efficacy of these therapies in cancer patients.

Strength Endurance Training but Not Intensive Strength Training Reduces Senescence-Prone T Cells in Peripheral Blood in Community-Dwelling Elderly Women

Aging is characterized by a progressive decline in immune function known as immunosenescence. Although the causes of immunosenescence are likely to be multifactorial, an age-associated accumulation of senescent T cells and decreased naive T-cell repertoire are key contributors to the phenomenon. On the other hand, there is a growing consensus that physical exercise may improve immune response in aging. However, the optimum training modality required to obtain beneficial adaptations in older subjects is lacking. Therefore, we aimed to investigate the effects of exercise modality on T-cell phenotypes in older women. A total of 100 women (aged ≥ 65 years) were randomized to either intensive strength training (80% of one-repetition maximum ), strength endurance training (40% one-repetition maximum), or control (stretching exercise) for 2-3 times per week during 6 weeks. The T-cell percentages and absolute counts were determined using flow cytometry and a hematology analyzer. C-reactive protein was measured using immunonephelometry. We report for the first time that 6 weeks of strength endurance training significantly decreased the basal percentage and absolute counts of senescence-prone T cells, which was positively related to the number of training sessions performed. Conceivably, training protocols with many repetitions-at a sufficiently high external resistance-might assist the reduction of senescence-prone T cells in older women.

COVID-19 pathophysiology: A review

In December 2019, a novel coronavirus, now named as SARS-CoV-2, caused a series of acute atypical respiratory diseases in Wuhan, Hubei Province, China. The disease caused by this virus was termed COVID-19. The virus is transmittable between humans and has caused pandemic worldwide. The number of death tolls continues to rise and a large number of countries have been forced to do social distancing and lockdown. Lack of targeted therapy continues to be a problem. Epidemiological studies showed that elder patients were more susceptible to severe diseases, while children tend to have milder symptoms. Here we reviewed the current knowledge about this disease and considered the potential explanation of the different symptomatology between children and adults.

Bone marrow is the preferred site of memory CD4+ T cell proliferation during recovery from sepsis

Sepsis survivors suffer from increased vulnerability to infections, and lymphopenia presumably contributes to this problem. The mechanisms of the recovery of memory CD4+ T cells after sepsis remain elusive. We used the cecal ligation and puncture mouse model of sepsis to study the restoration of the memory CD4+ T cells during recovery from sepsis. Then, adoptive transfer of antigen-specific naive CD4+ T cells followed by immunization and BrdU labeling were performed to trace the proliferation and migration of memory CD4+ T cells. We revealed that the bone marrow (BM) is the primary site of CD4+ memory T cell homing and proliferation after sepsis-induced lymphopenia. Of interest, BM CD4+ T cells had a higher basal proliferation rate in comparison with splenic T cells. These cells also show features of resident memory T cells yet have the capacity to migrate outside the BM niche and engraft secondary lymphoid organs. The BM niche also sustains viability and functionality of CD4+ T cells. We also identified IL-7 as the major inducer of proliferation of the BM memory CD4+ T cells and showed that recombinant IL-7 improves the recovery of these cells. Taken together, we provide data on the mechanism and location of memory CD4+ T cell proliferation during recovery from septic lymphopenia, which are of relevance in studying immunostimulatory therapies in sepsis.

Single-cell transcriptomics identifies an effectorness gradient shaping the response of CD4+ T cells to cytokines

Naïve CD4⁺ T cells coordinate the immune response by acquiring an effector phenotype in response to cytokines. However, the cytokine responses in memory T cells remain largely understudied. Here we use quantitative proteomics, bulk RNA-seq, and single-cell RNA-seq of over 40,000 human naïve and memory CD4⁺ T cells to show that responses to cytokines differ substantially between these cell types. Memory T cells are unable to differentiate into the Th2 phenotype, and acquire a Th17-like phenotype in response to iTreg polarization. Single-cell analyses show that T cells constitute a transcriptional continuum that progresses from naïve to central and effector memory T cells, forming an effectorness gradient accompanied by an increase in the expression of chemokines and cytokines. Finally, we show that T cell activation and cytokine responses are influenced by the effectorness gradient. Our results illustrate the heterogeneity of T cell responses, furthering our understanding of inflammation.

Cytokines critically control the differentiation and functions of activated naïve and memory T cells. Here the authors show, using multi-omics and single-cell analyses, that naïve and memory T cells exhibit distinct cytokine responses, in which an ‘effectorness gradient’ is depicted by a transcriptional continuum, which shapes the downstream genetic programs.

Uremia-Associated Ageing of the Thymus and Adaptive Immune Responses

Progressive loss of renal function is associated with a series of changes of the adaptive immune system which collectively constitute premature immunological ageing. This phenomenon contributes significantly to the mortality and morbidity of end-stage renal disease (ESRD) patients. In this review, the effect of ESRD on the T cell part of the adaptive immune system is highlighted. Naïve T cell lymphopenia, in combination with the expansion of highly differentiated memory T cells, are the hallmarks of immunological ageing. The decreased production of newly formed T cells by the thymus is critically involved. This affects both the CD4 and CD8 T cell compartment and may contribute to the expansion of memory T cells. The expanding populations of memory T cells have a pro-inflammatory phenotype, add to low-grade inflammation already present in ESRD patients and destabilize atherosclerotic plaques. The effect of loss of renal function on the thymus is not reversed after restoring renal function by kidney transplantation and constitutes a long-term mortality risk factor. Promising results from animal experiments have shown that rejuvenation of the thymus is a possibility, although not yet applicable in humans.

Influence of age on the efficacy of immune checkpoint inhibitors in advanced cancers: a systematic review and meta-analysis

Background: Immune checkpoint inhibitors (ICIs) represent a paradigm shift in the development of cancer treatment. However, it remains to be clarified whether the benefits that they confer differ according to patient age. We conducted a systematic review and meta-analysis to assess age differences in the benefits of ICI treatment.Methods: We systematically searched the PubMed database for randomised controlled trials of ICIs, including PD-1, PD-L1 and CTLA-4 inhibitors across multiple cancer types, such as melanoma, lung cancer and gastric cancer. We extracted trials including hazard ratios (HRs) for death stratified by patient age (cut-off age, 65 years). The primary objective of this study was to assess the difference in ICI efficacy between younger and older patients. We calculated pooled HRs and 95% confidence intervals (CIs) for younger and older cancer patients, and assessed data heterogeneity.Results: We identified 3999 studies in our search. Of these, 24 eligible randomised trials, including a total of 8157 (57%) younger and 6104 (43%) older cancer patients, fulfilled the criteria for our study and were thus further analysed. The pooled HRs of the younger and older patients were 0.76 (95% CI: 0.69-0.84) and 0.80 (95% CI: 0.71-0.86), respectively; the difference in ICI efficacy between younger and older cancer patients was not significant (p = .82). Regarding the PD-1 and PD-L1 inhibitors, the survival benefit was similar in both age groups (HR: 0.74; p = .96), whereas for the CTLA-4 inhibitors, there tended to be less survival benefit for older versus younger patients (HR: 0.90 and 0.77, respectively; p = .26).Conclusions: The survival benefit conferred by ICI was not age-dependent, amongst patients aged 65 years or younger. However, age-dependent benefits may vary amongst different types of ICIs.

Inflammaging is associated with shifted macrophage ontogeny and polarization in the aging mouse ovary

The fertility of women declines sharply after age 35 and is essentially lost upon menopause at age 51. The ovary plays an important part in aging-associated changes in women's physiology since it is an essential component of both the reproductive and endocrine systems. Several previous studies in mice have shown that the ovarian tissue goes through drastic changes over the course of aging and exhibits signs of aging-associated chronic inflammation (inflammaging), which may contribute to the marked decline of oocyte quality in aged individuals. To further examine aging-associated gene expression changes in the ovary and to characterize the development of inflammaging, we performed detailed transcriptomic analysis of whole ovaries from mice of six different age groups over the mouse reproductive lifespan and identified more than 5000 genes with significant expression change over the course of aging. Intriguingly, we found aging-associated changes in the expression of several markers that indicate alterations in the composition of ovarian macrophages, which are known to be central players of inflammaging. Using flow cytometry, we analyzed and compared macrophage populations and polarization in young and old ovaries and found a significant increase in monocyte recruitment and macrophage alternative activation (M2) in the old ovaries compared to those in young. Our results are consistent with previous findings of aging-associated increase of fibrosis in the ovarian stromal extracellular matrix, and they provide new clues about the development of inflammaging in the mammalian ovary.

Diversity of Salmonella Typhi-responsive CD4 and CD8 T cells before and after Ty21a typhoid vaccination in children and adults

Typhoid fever is a life-threatening disease caused by the human-restricted pathogen Salmonella enterica serovar Typhi (S. Typhi). The oral live attenuated Ty21a typhoid vaccine protects against this severe disease by eliciting robust, multifunctional cell-mediated immunity (CMI), shown to be associated with protection in wild-type S. Typhi challenge studies. Ty21a induces S. Typhi-responsive CD8+ and CD4+ T cells but little is known about the response to this vaccine in children. To address this important gap in knowledge, we have used mass cytometry to analyze pediatric and adult pre- and post-Ty21a vaccination CMI in an autologous S. Typhi antigen presentation model. Here, using conventional supervised analytical tools, we show adult T cells are more multifunctional at baseline than those obtained from children. Moreover, pediatric and adult T cells respond similarly to Ty21a vaccination, but adult responders remain more multifunctional. The use of the unsupervised dimensionality reduction tool tSNE (t-distributed Stochastic Neighbor Embedding) allowed us to confirm these findings, as well as to identify increases and decreases in well-defined specific CD4+ and CD8+ T-cell populations that were not possible to uncover using the conventional gating strategies. These findings evidenced age-associated maturation of multifunctional S. Typhi-responsive T-cell populations, including those which we have previously shown to be associated with protection from, and/or delayed onset of, typhoid disease. These findings are likely to play an important role in improving pediatric vaccination strategies against S. Typhi and other enteric pathogens.

Moroccan lymphocyte subsets reference ranges: age, gender, ethnicity, and socio-economic factors dependent differences

Lymphocyte subsets reference ranges are helpful for a precise diagnosis and therapy of various diseases. We attempted in the current study to establish Moroccan lymphocyte reference range and reveal age, gender, ethnicity, income, and instructional levels dependent differences. Lymphocyte subsets percentage and absolute count were determined by 4-color flow cytometry in a population study of 145 adults Moroccan healthy volunteers. Analysis showed significant age-dependent changes. Age was associated with a decrease of naïve CD4+ and CD8+ T cells and an increase of memory CD4+ or CD8+ T cells. Activated CD4+ CD38+ and CD8+ CD38+ T cells, Treg as well as NK cell showed age-dependent alterations. In contrast, B cells remained unchanged. A higher percentage of CD3+ and CD4+ T cells was observed in females while CD8+, B and NK cells count were higher in men. Ethnicity, instructional levels, and personal income seem to not influence lymphocyte subsets reference values. This study provides reference ranges for lymphocyte subsets of healthy Moroccan adults. These results can be used for other North African (Maghrebian) countries considering their geographic, ethnic, economic, and cultural similarities.

How the ageing microenvironment influences tumour progression

Most cancers arise in individuals over the age of 60. As the world population is living longer and reaching older ages, cancer is becoming a substantial public health problem. It is estimated that, by 2050, more than 20% of the world's population will be over the age of 60 - the economic, healthcare and financial burdens this may place on society are far from trivial. In this Review, we address the role of the ageing microenvironment in the promotion of tumour progression. Specifically, we discuss the cellular and molecular changes in non-cancerous cells during ageing, and how these may contribute towards a tumour permissive microenvironment; these changes encompass biophysical alterations in the extracellular matrix, changes in secreted factors and changes in the immune system. We also discuss the contribution of these changes to responses to cancer therapy as ageing predicts outcomes of therapy, including survival. Yet, in preclinical studies, the contribution of the aged microenvironment to therapy response is largely ignored, with most studies designed in 8-week-old mice rather than older mice that reflect an age appropriate to the disease being modelled. This may explain, in part, the failure of many successful preclinical therapies upon their translation to the clinic. Overall, the intention of this Review is to provide an overview of the interplay that occurs between ageing cell types in the microenvironment and cancer cells and how this is likely to impact tumour metastasis and therapy response.

Moderate levels of physical fitness maintain telomere length in non-senescent T CD8+ cells of aged men

OBJECTIVES

Immunosenescence is an age-associated change characterized by a decreased immune response. Although physical activity has been described as fundamental for maintaining the quality of life, few studies have evaluated the effects of different levels of exercise on telomere length in aged populations. The present study aimed to analyze the effects of different levels of physical activity, classified by the Maximal oxygen consumption (VO2 max) values, on the telomere length of memory Cluster of differentiation (CD) CD4+(CD45ROneg and CD45RO+), effector CD8+CD28neg, and CD8+CD28+ T cells in aged individuals.

METHODS

Fifty-three healthy elderly men (aged 65-85 years) were included in this study. Their fitness level was classified according to the American College of Sports Medicine (ACSM) for VO2 max (mL/kg/min). Blood samples were obtained from all participants to analyze the percentage of CD3, CD4, CD8, CD28+, naïve, and subpopulations of memory T cells by using flow cytometry. Furthermore, using the Flow-FISH methodology, the CD4+CD45RO+, CD4+CD45ROneg, CD8+CD28+, and CD8+CD28negT cell telomere lengths were measured.

RESULTS

There was a greater proportion of effector memory T CD4+ cells and longer telomeres in CD8+CD28+ T cells in the moderate physical fitness group than in the other groups. There was a higher proportion of terminally differentiated memory effector T cells in the low physical fitness group.

CONCLUSION

A moderate physical activity may positively influence the telomere shortening of CD28+CD8+T cells. However, additional studies are necessary to evaluate the importance of this finding with regard to immune function responses in older men.

Overview of Basic Immunology and Clinical Application

Tumor exists as a complex network of structures with an ability to evolve and evade the host immune surveillance mechanism. The immune milieu which includes macrophages, dendritic cells, natural killer cells, neutrophils, mast cells, B cells, and T cells are found in the core, the invasive margin, or the adjacent stromal or lymphoid component of the tumor. The immune infiltrate is heterogeneous and varies within a patient and between patients of the same tumor histology. The location, density, functionality, and cross-talk between the immune cells in the tumor microenvironment influence the nature of immune response, prognosis, and treatment outcomes in cancer patients. Therefore, an understanding of the characteristics of the immune cells and their role in tumor immune surveillance is of paramount importance to identify immune targets and to develop novel immune therapeutics in the war against cancer. In this chapter, we provide an overview of the individual components of the human immune system and the translational relevance of predictive biomarkers.

Establishment of normative ranges of the healthy human immune system with comprehensive polychromatic flow cytometry profiling

Existing normative flow cytometry data have several limitations including small sample sizes, incompletely described study populations, variable flow cytometry methodology, and limited depth for defining lymphocyte subpopulations. To overcome these issues, we defined high-dimensional flow cytometry reference ranges for the healthy human immune system using Human Immunology Project Consortium methodologies after carefully screening 127 subjects deemed healthy through clinical and laboratory testing. We enrolled subjects in the following age cohorts: 18–29 years, 30–39, 40–49, and 50–66 and enrolled cohorts to ensure an even gender distribution and at least 30% non-Caucasians. From peripheral blood mononuclear cells, flow cytometry reference ranges were defined for >50 immune subsets including T-cell (activation, maturation, T follicular helper and regulatory T cell), B-cell, and innate cells. We also developed a web tool for visualization of the dataset and download of raw data. This dataset provides the immunology community with a resource to compare and extract data from rigorously characterized healthy subjects across age groups, gender and race.

Evolution of pathologic T-cell subsets in patients with atopic dermatitis from infancy to adulthood

BACKGROUND

The circulating immune phenotype was defined in adults and young children with early atopic dermatitis (AD), but chronologic changes in the blood of infants and children with AD through adolescence have not been explored.

OBJECTIVE

We sought to compare immune activation and cytokine polarization in the blood of 0- to 5-year-old (n = 39), 6- to 11-year-old (n = 26), 12- to 17-year-old (n = 21) and 18-year-old or older (n = 43) patients with AD versus age-matched control subjects.

METHODS

Flow cytometry was used to measure IFN-γ, IL-9, IL-13, IL-17, and IL-22 cytokine levels in CD4⁺/CD8⁺ T cells, with inducible costimulator molecule and HLA-DR defining midterm and long-term T-cell activation, respectively, within skin-homing/cutaneous lymphocyte antigen (CLA)⁺ versus systemic/CLA^- T cells. Unsupervised clustering differentiated patients based on their blood biomarker frequencies.

RESULTS

Although CLA⁺ T_H1 frequencies were significantly lower in infants with AD versus all older patients (P < .01), frequencies of CLA⁺ T_H2 T cells were similarly expanded across all AD age groups compared with control subjects (P < .05). After infancy, CLA^- T_H2 frequencies were increased in patients with AD in all age groups, suggesting systemic immune activation with disease chronicity. IL-22 frequencies serially increased from normal levels in infants to highly significant levels in adolescents and adults compared with levels in respective control subjects (P < .01). Unsupervised clustering aligned the AD profiles along an age-related spectrum from infancy to adulthood (eg, inducible costimulator molecule and IL-22).

CONCLUSIONS

The adult AD phenotype is achieved only in adulthood. Unique cytokine signatures characterizing individual pediatric endotypes might require age-specific therapies. Future longitudinal studies, comparing the profile of patients with cleared versus persistent pediatric AD, might define age-specific changes that predict AD clearance.

Long-term use of interferon-β in multiple sclerosis increases Vδ1-Vδ2-Vγ9- γδ T cells that are associated with a better outcome

Background

We previously reported that Vδ2⁺Vγ9⁺ γδ T cells were significantly decreased in multiple sclerosis (MS) patients without disease-modifying therapies (untreated MS) and were negatively correlated with Expanded Disability Status Scale (EDSS) scores, suggesting protective roles of Vδ2⁺Vγ9⁺ γδ T cells. Interferon-β (IFN-β) is one of the first-line disease-modifying drugs for MS. However, no previous studies have reported changes in γδ T cell subsets under IFN-β treatment. Therefore, we aimed to clarify the effects of the long-term usage of IFN-β on γδ T cell subsets in MS patients.

Methods

Comprehensive flow cytometric immunophenotyping was performed in 35 untreated MS and 21 MS patients on IFN-β for more than 2 years (IFN-β-treated MS) including eight super-responders fulfilling no evidence of disease activity criteria, and 44 healthy controls (HCs).

Results

The percentages of Vδ2⁺Vγ9⁺ cells in γδ T cells were significantly lower in untreated and IFN-β-treated MS patients than in HCs. By contrast, the percentages of Vδ1⁻Vδ2⁻Vγ9⁻ cells in γδ T cells were markedly higher in IFN-β-treated MS patients than in HCs and untreated MS patients (both p < 0.001). A significant negative correlation between the percentages of Vδ2⁺Vγ9⁺ cells in γδ T cells and EDSS scores was confirmed in untreated MS but not evident in IFN-β-treated MS. Moreover, class-switched memory B cells were decreased in IFN-β-treated MS compared with HCs (p < 0.001) and untreated MS patients (p = 0.006). Interestingly, the percentages of Vδ1⁻Vδ2⁻Vγ9⁻ cells in γδ T cells were negatively correlated with class-switched memory B cell percentages in all MS patients (r = − 0.369, p = 0.005), and the percentages of Vδ1⁻Vδ2⁻Vγ9⁻ cells in Vδ1⁻Vδ2⁻ γδ T cells were negatively correlated with EDSS scores only in IFN-β super-responders (r = − 0.976, p < 0.001).

Conclusions

The present study suggests that long-term usage of IFN-β increases Vδ1⁻Vδ2⁻Vγ9⁻ γδ T cells, which are associated with a better outcome, especially in IFN-β super-responders. Thus, increased Vδ1⁻Vδ2⁻Vγ9⁻ cells together with decreased class-switched memory B cells may contribute to the suppression of disease activity in MS patients under IFN-β treatment.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1574-5) contains supplementary material, which is available to authorized users.

Age related human T cell subset evolution and senescence

T cells are fundamental effector cells against viruses and cancers that can be divided into different subsets based on their long-term immune protection and immediate immune response effects. The percentage and absolute number of these subsets change with ageing, which leads to a reduced immune response in older individuals. Stem cell memory T cells (T_SCM) represent a small population of memory T cells with enhanced proliferation and differentiation properties that are endowed with high potential for maintaining T cell homeostasis. However, whether these cells change with ageing and gender remains unknown. Here, we assayed the distribution of T_SCM and other T cell subsets in peripheral blood from 92 healthy subjects (44 females and 48 males) ranging from 3 to 88 years old by flow cytometry. We found that CD4+ and CD8+ T_SCM in the circulation have relatively stable frequencies, and the absolute number of CD8+ T_SCM decreased with age; however, the ratio of T_SCM to the CD4+ or CD8+ naïve population increased with age. Unlike the obvious changes in other T cell subsets with age and gender, the stable level of T_SCM in peripheral blood may support their capacity for sustaining long-term immunological memory, while their importance may increase together with ageing.

Frontline Science: Exhaustion and senescence marker profiles on human T cells in BRGSF-A2 humanized mice resemble those in human samples

This work sought to confirm the human-like expression of exhaustion and senescence markers in a mouse model with a humanized immune system (HIS): the Balb/c Rag2^KO IL2rgc^KO Sirpα^NOD Flk2^KO HLA-A2^HHD (BRGSF-A2) mouse reconstituted with human CD34⁺ cord blood cells. With regard to senescence markers, the percentage of CD57⁺ T cells was higher in the bone marrow (BM) than in the spleen or blood. The same was true for KLRG1⁺ hCD8⁺ T cells. With regard to exhaustion markers, the percentage of programmed death 1 (PD-1⁺ ) T cells was higher in the BM than in the spleen or blood; the same was true for TIGIT⁺ hCD4⁺ cells. These tissue-specific differences were related to both higher proportions of memory T cells in BM and intrinsic differences in expression within the memory fraction. In blood samples from HIS mice and healthy human donors (HDs), we found that the percentage of KLRG1⁺ cells among hCD8⁺ T cells was lower in HIS compared to HDs. The opposite was true for CD4⁺ T cells. Unexpectedly, a high frequency of KLRG1⁺ cells was observed among naive T cells in HIS mice. CD57 expression on T cells was similar in blood samples from HIS mice and HDs. Likewise, PD-1 expression was similar in the two systems, although a relatively low proportion of HIS hCD4⁺ T cells expressed TIGIT. The BRGSF-A2 HIS mouse's exhaustion and senescence profile was tissue specific and relatively human like; hence, this mouse might be a valuable tool for determining the preclinical efficacy of immunotherapies.

A longitudinal study of the stability, variability, and interdependencies among late-differentiated T and NK cell subsets in older adults

The stability and variability of older adults' late-differentiated peripheral blood T and natural killer (NK) cells over time remains incompletely quantified or understood. We examined the variability and change over time in T and NK cell subsets in a longitudinal sample of older adults; the effects of sex, cytomegalovirus (CMV) serostatus, and chronic disease severity on immune levels and trajectories; and interdependencies among T and NK cell subsets. Older adults (N = 149, age 64-94 years, 42% male) provided blood every 6 months for 2.5 years (up to 5 waves) to evaluate late-differentiated CD8 T cells (CD28-, CD57+) and CD56dimNK cells (CD57+, NKG2C+, FcɛRIγ-). In multilevel models, most of the variance in immune subsets reflected stable differences between people. However, CD56dimNK cell subsets (CD57+ and FcɛRIγ-) also increased with age, whereas T cell subsets did not. Independent of age, all subsets examined were higher in CMV-positive older adults. Men had higher levels of CD56dim CD57+ than women. Chronic disease was not associated with any immune subset investigated. T and NK cell subsets correlated within each cell type, but interdependencies differed by CMV serostatus. Our results suggest the accumulation of these stable cell populations may be driven less by chronological aging, even less by chronic disease severity, and more by CMV, which may differentially skew T and NK cell differentiation.

A Mathematical Model of the Effects of Aging on Naive T Cell Populations and Diversity

The human adaptive immune response is known to weaken in advanced age, resulting in increased severity of pathogen-born illness, poor vaccine efficacy, and a higher prevalence of cancer in the elderly. Age-related erosion of the T cell compartment has been implicated as a likely cause, but the underlying mechanisms driving this immunosenescence have not been quantitatively modeled and systematically analyzed. T cell receptor diversity, or the extent of pathogen-derived antigen responsiveness of the T cell pool, is known to diminish with age, but inherent experimental difficulties preclude accurate analysis on the full organismal level. In this paper, we formulate a mechanistic mathematical model of T cell population dynamics on the immunoclonal subpopulation level, which provides quantitative estimates of diversity. We define different estimates for diversity that depend on the individual number of cells in a specific immunoclone. We show that diversity decreases with age primarily due to diminished thymic output of new T cells and the resulting overall loss of small immunoclones.

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.

Switching renal transplant recipients to belatacept therapy: results of a real-life gradual conversion protocol

Conversion to belatacept immunosuppression is a therapeutic option for renal-transplant recipients with calcineurin inhibitors (CNI) toxicity, but it associates with high risk of acute rejection. Gradual conversion and serial immune monitoring with urinary chemokine CXCL9 may allow increasing safety of this maneuver. We converted kidney transplant recipients with signs of toxicity to CNI or other immunosuppressive drugs to belatacept over a 2-month period. We monitored renal function, metabolic profile, and circulating lymphocyte subsets. We also quantified urinary CXCL9 over a 12-month follow-up period. Between September 2016 and March 2017, 35 patients were successfully switched to belatacept immunosuppression at 3.3 (1.3-7.2) years after transplant. Two patients had a reversible rise in serum creatinine, associated with acute rejection in one case. Urinary CXCL9 increased before serum creatinine. After conversion, blood pressure and HbA1c significantly declined while eGFR and proteinuria remained stable. The percentage of circulating effector T cells and memory B cells significantly declined. Conversion from CNI to belatacept, in this setting, was feasible and safe, provided it was performed over a 2-month time-period. Monitoring urinary CXCL9 may further increase safety through earlier identification of patients at risk for acute rejection. The procedure associates with improved blood pressure, metabolic profile, and reduced circulating effector T and B cells.

Increased attrition of memory T cells during sepsis requires 2B4

Recent seminal studies have revealed that laboratory mice differ from adult humans with regard to the frequency, number, and distribution of memory T cells. Because our data show that memory T cells are more susceptible to sepsis-induced death than naive T cells, in this study we developed a model in which mice possess a memory T cell compartment more similar to that of adult humans, to better study immune responses during sepsis in the more physiologically relevant context of high frequencies of memory T cells. Using this model, we found that CD44hi memory T cells significantly upregulated the coinhibitory molecule 2B4 during sepsis, and 2B4+ memory T cells coexpressed markers of both activation and exhaustion. Genetic deficiency in 2B4 resulted in decreased mortality during sepsis. Mechanistically, this decreased mortality was associated with reduced caspase-3/7+ apoptotic T cells in 2B4-/- relative to WT, septic hosts. These results were corroborated by analysis of PBMCs isolated from human patients with sepsis, which showed increased frequencies of caspase-3/7+ apoptotic cells among 2B4+ relative to 2B4- T cells. Thus, 2B4 plays a critical role in sepsis-induced apoptosis in both murine memory T cells and those isolated from human patients with sepsis.

How a well-adapting immune system remembers

The adaptive immune system is able to protect us from a large variety of pathogens, even ones it has not seen yet. Can predicting the future pathogen distribution help in protection? We find that a combination of probabilistic forecasting and occasional sampling of the current environment reduces infection costs—a scheme easily implemented by the memory repertoire. The proposed theoretical framework offers a modular recipe for updating the memory repertoire, which quantitatively predicts the strength of the immune response in flu-vaccination experiments, unlike other update schemes. It also links the observed early life dynamics of the memory pool to the sparseness properties of the pathogen distribution and competitive receptor dynamics for pathogens.

An adaptive agent predicting the future state of an environment must weigh trust in new observations against prior experiences. In this light, we propose a view of the adaptive immune system as a dynamic Bayesian machinery that updates its memory repertoire by balancing evidence from new pathogen encounters against past experience of infection to predict and prepare for future threats. This framework links the observed initial rapid increase of the memory pool early in life followed by a midlife plateau to the ease of learning salient features of sparse environments. We also derive a modulated memory pool update rule in agreement with current vaccine-response experiments. Our results suggest that pathogenic environments are sparse and that memory repertoires significantly decrease infection costs, even with moderate sampling. The predicted optimal update scheme maps onto commonly considered competitive dynamics for antigen receptors.

Characteristics of regulatory T-cell populations before and after Ty21a typhoid vaccination in children and adults

Typhoid fever, caused by the pathogen Salmonella enterica serovar Typhi (S. Typhi), is a serious global health concern. Challenge studies with wild type S. Typhi identified associations between gut-homing regulatory T cells (Treg) and development of typhoid disease. Whether oral live-attenuated Ty21a vaccination induces gut-homing Treg remains unclear. Here, we analyze pediatric and adult Treg pre- and post-Ty21a vaccination in an autologous S. Typhi-antigen presentation model to address this knowledge gap. We show that peripheral memory Treg populations change from childhood to adulthood, but not following Ty21a vaccination. Unsupervised dimensionality reduction with t-distributed stochastic neighbor embedding (tSNE) identifies homing, memory, and functional features which evidence age-associated maturation of multifunctional S. Typhi-responsive Treg, which were not impacted by Ty21a vaccination. These findings improve understanding of pediatric regulatory T cells, while identifying age-related differences in S. Typhi-responsive Treg, which may aid in the development of improved pediatric vaccination strategies against S. Typhi.

Early immunologic changes during the onset of atopic dermatitis

OBJECTIVE

Atopic dermatitis (AD), which is commonly called eczema, is the most common chronic inflammatory skin disease. The pipeline of new targeted treatments is currently expanding, a development that is largely based on our increasing understanding of disease mechanisms. Mechanistic insights have long been based on long-standing adult AD. Recently, studies also investigated early pediatric AD at disease onset, and revealed several differences in barrier and immune properties when compared with long-standing adult AD. This review focuses on immunological changes very early in life that predispose to the development of AD, and summarizes characteristics of the molecular AD phenotype in this age group.

DATA SOURCES

Review of published literature.

STUDY SELECTIONS

Studies investigating human AD at disease onset in newborns, toddlers, and young children, in comparison with adults with long-standing disease.

RESULTS

Already in cord blood, increased Th2 and decreased Th1 levels were found to increase the risk of AD development. Both pediatric and adult AD share Th2/Th22 activation and defects in lipid barrier deposition and tight junction formation, but Th1 activation and epidermal differentiation complex defects are largely absent in pediatric AD.

CONCLUSION

Immune changes predisposing to AD development are present very early in life. During the first months of disease, AD shows various differences in immune and barrier properties from long-standing adult AD, which might necessitate tailored treatment approaches depending on the age of the patient.

Age-Associated Heterogeneity of Ty21a-Induced T Cell Responses to HLA-E Restricted Salmonella Typhi Antigen Presentation

Human-restricted Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of typhoid fever—a life-threatening disease of great global health significance, particularly in the developing world. Ty21a is an oral live-attenuated vaccine that protects against the development of typhoid disease in part by inducing robust T cell responses, among which multifunctional CD8⁺ cytotoxic T lymphocytes (CTL) play an important role. Following Ty21a vaccination, a significant component of adult CTL have shown to be targeted to S. Typhi antigen presented by the conserved major histocompatibility complex (MHC) class Ib molecule, human leukocyte antigen-E (HLA-E). S. Typhi challenge studies have shown that baseline, multifunctional HLA-E responsive T cells are associated with protection from, and delayed onset of, typhoid disease. However, despite the overwhelming burden of typhoid fever in school-aged children, and due to limited availability of pediatric samples, incomplete information is available regarding these important HLA-E-restricted responses in children, even though studies have shown that younger children may be less likely to develop protective cell mediated immune (CMI) responses than adults following vaccination. To address this gap, we have studied this phenomenon in depth by using mass cytometry to analyze pediatric and adult T cell responses to HLA-E-restricted S. Typhi antigen presentation, before and after Ty21a vaccination. Herein, we show variable responses in all age strata following vaccination among T effector memory (T_EM) and T effector memory CD45RA⁺ (T_EMRA) cells based on conventional gating analysis. However, by utilizing the dimensionality reduction tool tSNE (t-distributed Stochastic Neighbor Embedding), we are able to identify diverse, highly multifunctional gut-homing- T_EM and T_EMRA clusters of cells which are more abundant in adult and older pediatric participants than in younger children. These findings highlight a potential age-associated maturation of otherwise conserved HLA-E restricted T cell responses. Such insights, coupled with the marked importance of multifunctional T cell responses to combat infection, may better inform future pediatric vaccination strategies against S. Typhi and other infectious diseases.

The clinical implication of CD45RA+ naïve T cells and CD45RO+ memory T cells in advanced pancreatic cancer: a proxy for tumor biology and outcome prediction

Naïve and memory T cells play a pivotal role in solid tumor pathogenesis but their role in pancreatic cancer progression remains elusive. Thus, we aimed to investigate their clinical potential in advanced pancreatic cancer (APC). Flow cytometry was performed to evaluate the level of baseline peripheral naïve and memory T cells from 137 APC patients before receiving first‐line chemotherapy. Interrelationships between naïve, memory T cells and clinicopathological variables were evaluated using Pearson’s correlation. The prognostic impact of naïve and memory T cells were assessed by Kaplan‐Meier analysis and Cox regression. The correlation between naïve/memory T cells and tumor progression was investigated by Student’s t test. CD4⁺ naïve/memory ratio showed close correlations with hemoglobin, red blood cell (RBC), absolute neutrophil count (ANC) and platelet while CD8⁺ naïve/memory ratio was correlated with hemoglobin, RBC and CEA. Higher baseline lever of CD4⁺CD45RO⁺/CD4⁺ was correlated with better overall survival (OS) (P = 0.036). Patients with CD4⁺ naïve/memory ratio ≥0.36 had a poorer OS than those with CD4⁺ naïve/memory ratio <0.36 (P = 0.021). In addition, CD4⁺ naïve/memory ratio showed independent prognostic impact (HR 1.427, 95% CI 1.033‐1.973, P = 0.031). Furthermore, poorer clinical response was correlated with higher level of CD8⁺ naïve/memory ratio after the third cycle of chemotherapy (P = 0.01). Besides, patients with a lower level of CD8⁺ naïve/memory ratio had longer progression‐free survival (PFS) (P = 0.028). We propose CD4⁺ naïve/memory ratio as a novel prognostic biomarker for APC. In addition, CD8⁺ naïve/memory ratio can be a candidate marker for predicting PFS and the change of its level may reflect the progression of APC.

Aging and End Stage Renal Disease Cause A Decrease in Absolute Circulating Lymphocyte Counts with A Shift to A Memory Profile and Diverge in Treg Population

There is a growing number of elderly kidney transplant (Ktx) recipients. Elderly recipients present lower acute rejection rates but higher incidence of infection and malignancies. Aging per se seems to result in a shift to memory profile and chronic kidney disease (CKD) in premature immunological aging. Understanding aging and CKD effects on the immune system can improve elderly Ktx immunosuppression. We analyzed the effects of aging and CKD in the immune system, comparing healthy adults (HAd) (n=14, 26±2y), healthy elderly (HEld) (n=15, 79±7y), end stage renal disease (ESRD) adults (EnAd) (n=18, 36±7y) and ESRD elderly (EnEld) (n=31, 65±3y) prior to Ktx regarding their naïve, memory and regulatory T and B peripheral lymphocytes. Aging and ESRD presented additive effect decreasing absolute numbers of B and T-lymphocytes, affecting memory, naive and regulatory subsets without synergic effect. Both resulted in higher percentages of T memory subsets and opposing effects on regulatory T (TREG) subsets, higher percentage in aging and lower in ESRD. Combined effect of aging and ESRD also resulted in higher regulatory B cell percentages. In addition to global lymphopenia and TCD4⁺ memory shift in both aging and ESRD, aging shifts to an immunoregulatory profile, inducing a increase in TREG percentages, contrasting with ESRD that decreases TREGs. Differential immunosuppression regimens for elderly Ktx may be required. (ClinicalTrials.gov number: NTC01631058).

Impact of aging on inflammatory and immune responses during elastin peptide-induced murine emphysema

Deterioration of lung functions and degradation of elastin fibers with age are accelerated during chronic obstructive pulmonary disease (COPD). Excessive genesis of soluble elastin peptides (EP) is a key factor in the pathophysiology of COPD. We have previously demonstrated that 6-wk-old mice exhibited emphysematous structural changes associated with proinflammatory immune response after EP instillation. In this study, we investigated the consequences of aging on inflammatory, immune, and histological criteria associated with murine emphysema progression after EP exposure. Young (6 wk old) and elderly (15 mo old) C57BL/6J mice were endotracheally instilled with EP, and, at various time points after treatment, the inflammatory cell profiles from bronchoalveolar lavage fluids (BALF) and the T-lymphocyte phenotypes, at local and systemic levels, were analyzed by flow cytometry. Lungs were also prepared to allow morphological and histological analysis by confocal microscopy. Elderly mice exhibited an earlier development of pulmonary emphysema, characterized by an increase of the inflammatory and lymphocytic infiltrates, extracellular matrix breakdown, and airspace enlargement compared with young mice. This age-dependent parenchymal tissue remodeling was associated with an increase of the matrix metalloproteinase expressions and desmosine levels in BALF and/or sera of EP-treated mice. In addition, both the proportion of CD4⁺CD28^- and CD8⁺CD28^- T cells in the tissues of EP-treated mice and the interferon-γ levels in the EP-specific memory T-cell clones were significantly higher in elderly versus younger mice. This study demonstrates that aging accelerates emphysema development and that this effect is linked to increased EP production and their effects on inflammatory and immune response.

Sepsis erodes CD8+ memory T cell-protective immunity against an EBV homolog in a 2B4-dependent manner

Epstein-Barr virus (EBV) reactivation commonly occurs following sepsis, but the mechanisms underlying this are unknown. We utilized a murine EBV homolog (gHV) and the cecal ligation and puncture model of polymicrobial sepsis to study the impact of sepsis on gHV reactivation and CD8⁺ T cell immune surveillance following a septic insult. We observed a significant increase in the frequency of gHV-infected germinal center B cells on day 7 following sepsis. This increase in viral load was associated with a concomitant significant decrease in the frequencies of gHV-specific CD8⁺ T cells, as measured by class I MHC tetramers corresponding to the immunodominant viral epitopes. Phenotypic analysis revealed an increased frequency of gHV-specific CD8⁺ T cells expressing the 2B4 coinhibitory receptor in septic animals compared with sham controls. We sought to interrogate the role of 2B4 in modulating the gHV-specific CD8⁺ T cell response during sepsis. Results indicated that in the absence of 2B4, gHV-specific CD8⁺ T cell populations were maintained during sepsis, and gHV viral load was unchanged in 2B4^-/- septic animals relative to 2B4^-/- sham controls. WT CD8⁺ T cells upregulated PD-1 during sepsis, whereas 2B4^-/- CD8⁺ T cells did not. Finally, adoptive transfer studies revealed a T cell-intrinsic effect of 2B4 coinhibition on virus-specific CD8⁺ T cells and gHV viral load during sepsis. These data demonstrate that sepsis-induced immune dysregulation erodes antigen-specific CD8⁺ responses against a latent viral infection and suggest that blockade of 2B4 may better maintain protective immunity against EBV in the context of sepsis.

Immunosenescence and Respiratory Infections Among Nursing Home Residents

Residents of nursing homes are at high risk of infectious complications due to respiratory infection. The nursing home setting places residents at high risk given the frequent contact among residents and by staff along with the possibility for continuous introduction of respiratory viruses from the community. Nursing home residents are among the most frail members of society. They have multiple comorbidities that can increase their risk of infection. Immunosenescence plays an important role in not only rendering these seniors susceptible in infection, particularly viral respiratory infection, but also interferes with protection. That is, the ability to mount a robust immune response to influenza and pneumococcal vaccine increase the risk. There have been a number of T cell deficits described in this population. CD4+ T cells, in particular T-regs and CMV-reactive CD4+ T cells, have been shown to be predictive of respiratory viral infection in this population. Although evidence exists that T cell subsets may correlate better with response to vaccine and protection, antibody responses to influenza vaccine remains an important correlate in this population. Large-scale epidemiologic studies are needed to establish better correlation between biomarkers for protection and respiratory and other pathogens that circulate in nursing homes.

Distinct transcriptomic profiles of early-onset atopic dermatitis in blood and skin of pediatric patients

BACKGROUND

Atopic dermatitis (AD) predominantly affects young children, but our understanding of AD pathogenesis is based on skin and blood samples from long-standing adult AD. Genomic biopsy profiling from early pediatric AD showed significant Th2 and Th17/Th22-skewing, without the characteristic adult Th1 up-regulation. Because obtaining pediatric biopsies is difficult, blood gene expression profiling may provide a surrogate for the pediatric skin signature.

OBJECTIVE

To define the blood profile and associated biomarkers of early moderate-to-severe pediatric AD.

METHODS

We compared microarrays and reverse transcription polymerase chain reaction (RT-PCR) of blood cells from 28 AD children (<5 years and within 6 months of disease onset) to healthy control blood cells. Differentially expressed genes (DEGs) in blood (fold change [FCH] > 1.2 and false discovery rate [FDR] < 0.05) were then compared with skin DEGs.

RESULTS

Eosinophil and Th2 markers (IL5RA, IL1RL1/ST2, HRH4, CCR3, SIGLEC8, PRSS33, CLC from gene arrays; IL13/IL4/CCL22 from RT-PCR) were up-regulated in early pediatric AD blood, whereas IFNG/Th1 was decreased. Th1 markers were negatively correlated with clinical severity (EASI, pruritus, transepidermal water loss [TEWL]), whereas Th2/Th17-induced interleukin (IL)-19 was positively correlated with SCORAD. Although a few RT-PCR-defined immune markers (IL-13/CCL22) were increased in blood, as previously also reported for skin, minimal overlap based on gene array DEGs was seen.

CONCLUSION

The whole blood signature of early moderate-to-severe pediatric AD blood cells show predominantly a Th2/eosinophil profile; however, markers largely differ from the skin profile. Given their complementarity, pooling of biomarkers from blood and skin may improve profiling and predictions, providing insight regarding disease course, allergic comorbidity development, and response to systemic medications.

Age Correlates with Response to Anti-PD1, Reflecting Age-Related Differences in Intratumoral Effector and Regulatory T-Cell Populations

Purpose: We have shown that the aged microenvironment increases melanoma metastasis, and decreases response to targeted therapy, and here we queried response to anti-PD1.Experimental Design: We analyzed the relationship between age, response to anti-PD1, and prior therapy in 538 patients. We used mouse models of melanoma, to analyze the intratumoral immune microenvironment in young versus aged mice and confirmed our findings in human melanoma biopsies.Results: Patients over the age of 60 responded more efficiently to anti-PD-1, and likelihood of response to anti-PD-1 increased with age, even when we controlled for prior MAPKi therapy. Placing genetically identical tumors in aged mice (52 weeks) significantly increased their response to anti-PD1 as compared with the same tumors in young mice (8 weeks). These data suggest that this increased response in aged patients occurs even in the absence of a more complex mutational landscape. Next, we found that young mice had a significantly higher population of regulatory T cells (Tregs), skewing the CD8+:Treg ratio. FOXP3 staining of human melanoma biopsies revealed similar increases in Tregs in young patients. Depletion of Tregs using anti-CD25 increased the response to anti-PD1 in young mice.Conclusions: While there are obvious limitations to our study, including our inability to conduct a meta-analysis due to a lack of available data, and our inability to control for mutational burden, there is a remarkable consistency in these data from over 500 patients across 8 different institutes worldwide. These results stress the importance of considering age as a factor for immunotherapy response. Clin Cancer Res; 24(21); 5347-56. ©2018 AACR See related commentary by Pawelec, p. 5193.

Rapamycin Prolongs Graft Survival and Induces CD4+IFN-γ+IL-10+ Regulatory Type 1 Cells in Old Recipient Mice

BACKGROUND

Although the elderly represents a rapidly growing population among transplant recipients, age-specific aspects have not been considered sufficiently in clinical trials. Moreover, age-specific effects of immunosuppressive therapies remain poorly understood.

METHODS

Here, we assessed the impact of rapamycin on alloimmune responses in old recipients using a fully major histocompatibility complex-mismatched murine transplantation model.

RESULTS

Old untreated recipients displayed a prolonged skin graft survival compared to their young counterparts, an observation that confirmed data of our previous experiments. Rapamycin led to a significant prolongation of graft survival in both young and old recipients. However, graft survival was age-dependent and extended in old versus young recipients (19 days vs 12 days, P = 0.004). This age-specific effect was not linked to changes in frequencies or subset composition of either cluster of differentiation (CD)8 or CD4 T cells. Moreover, antiproliferative effects of rapamycin on CD8 and CD4 T cells as assessed by in vivo bromdesoxyuridine incorporation were comparable and age-independent. In contrast, the systemic production of IL-10 was markedly elevated in old recipients treated with rapamycin. In parallel to this shift in cytokine balance, IFN-γ/IL-10 double-positive regulatory type 1 cells emerged during T helper type 1 differentiation of old T helper cells in presence of rapamycin. Similarly, CD4IFN-γIL-10 cells expanded among Foxp3-negative cells after in vivo treatment of old recipients with rapamycin.

CONCLUSIONS

Our results highlight novel aspects of age-dependent immunosuppressive effects of rapamycin, with relevance for age-specific immunosuppressive regimens.

Human T Cell Development, Localization, and Function throughout Life

Throughout life, T cells coordinate multiple aspects of adaptive immunity, including responses to pathogens, allergens, and tumors. In mouse models, the role of T cells is studied in the context of a specific type of pathogen, antigen, or disease condition over a limited time frame, whereas in humans, T cells control multiple insults simultaneously throughout the body and maintain immune homeostasis over decades. In this review, we discuss how human T cells develop and provide essential immune protection at different life stages and highlight tissue localization and subset delineation as key determinants of the T cell functional role in immune responses. We also discuss how anatomic compartments undergo distinct age-associated changes in T cell subset composition and function over a lifetime. It is important to consider age and tissue influences on human T cells when developing targeted strategies to modulate T cell-mediated immunity in vaccines and immunotherapies.

Memory T cells skew toward terminal differentiation in the CD8+ T cell population in patients with acute myeloid leukemia

Stem cell memory T (T_SCM) and central memory T (T_CM) cells can rapidly differentiate into effector memory (T_EM) and terminal effector (T_EF) T cells, and have the most potential for immunotherapy. In this study, we found that the frequency of T_SCM and T_CM cells in the CD8+ population dramatically decreased together with increases in T_EM and T_EF cells, particularly in younger patients with acute myeloid leukemia (AML) (< 60 years). These alterations persisted in patients who achieved complete remission after chemotherapy. The decrease in T_SCM and T_CM together with the increase in differentiated T_EM and T_EF subsets in CD8+ T cells may explain the reduced T cell response and subdued anti-leukemia capacity in AML patients.

Parameters of the Immune System and Vitamin D Levels in Old Individuals

Aim

The increased number of individuals older than 80 years, centenarians, and supercentenarians is not a synonym for healthy aging, since severe infections, hospitalization, and disability are frequently observed. In this context, a possible strategy is to preserve the main characteristics/functions of the immune system with the aim to cause less damage to the organism during the aging process. Vitamin D acts on bone marrow, brain, breast, malignant cells, and immune system and has been recommended as a supplement. We aimed to evaluate whether immune parameters and vitamin D serum levels are correlated.

Methods

We evaluated some features of the immune system using the peripheral blood of individuals older than 80 years (n = 12) compared to young subjects (n = 10). In addition, we correlated these findings with vitamin D serum levels.

Results

Old individuals presented metabolic parameters of healthy aging and maintained preserved some features of immunity such as CD4/CD8 ratio, and low production of pro-inflammatory cytokines after stimulus. On the other hand, we observed increase in the frequency of myeloid-derived suppressor cells, reduction in circulating leukocytes, in the percentage of total CD8+, and in CD8+ Naïve T cells, in addition to increase in the percentage of CD8+ effector memory re-expressing CD45RA (EMRA) T cells. We found seropositivity for CMV in 97.7%, which was correlated with the decrease of CD8+ Naïve T cells and increase in CD8+ EMRA T cells. Vitamin D levels were insufficient in 50% of old individuals and correlated positively with total CD8+ T cells and negatively with CD8+ EMRA T cells.

Conclusion

In the studied population, longevity was correlated to maintenance of some immune parameters. Considering the limitations of the study as size of the sample and lack of functional assays, it was found that vitamin D in old individuals was correlated to some features of the immune system, mainly in the CD8 compartment.

Aging and lymphocyte changes by immunomodulatory therapies impact PML risk in multiple sclerosis patients

New potent immunomodulatory therapies for multiple sclerosis (MS) are associated with increased risk for progressive multifocal leukoencephalopathy (PML). It is unclear why a subset of treated patients develops PML, but patient age has emerged as an important risk factor. PML is caused by the JC virus and aging is associated with immune senescence, which increases susceptibility to infection. With the goal of improving PML risk stratification, we here describe the lymphocyte changes that occur with disease-modifying therapies (DMTs) associated with high or moderate risk toward PML in MS patients, how these changes compare to immune aging, and which measures best correlate with risk. We reviewed studies examining how these therapies alter patient immune profiles, which revealed the induction of changes to lymphocyte number and/or function that resemble immunosenescence. Therefore, the immunosuppressive activity of these MS DMTs may be enhanced in the context of an immune system that is already exhibiting features of senescence.

Decreased circulating T regulatory lymphocytes in obese patients undergoing bariatric surgery

OBJECTIVE

It has been previously demonstrated that T lymphocytes may be involved in the development of hypertension and microvascular remodeling, and that circulating T effector lymphocytes may be increased in hypertension. In particular, Th1 and Th 17 lymphocytes may contribute to the progression of hypertension and microvascular damage while T-regulatory (Treg) lymphocytes seem to be protective in this regard. However, no data is available about patients with severe obesity, in which pronounced microvascular alterations were observed.

DESIGN AND METHODS

We have investigated 32 severely obese patients undergoing bariatric surgery, as well as 24 normotensive lean subjects and 12 hypertensive lean subjects undergoing an elective surgical intervention. A peripheral blood sample was obtained before surgery for assessment of CD4+ T lymphocyte subpopulations. Lymphocyte phenotype was evaluated by flow cytometry in order to assess T-effector and Treg lymphocytes.

RESULTS

A marked reduction of several Treg subpopulations was observed in obese patients compared with controls, together with an increased in CD4+ effector memory T-effector cells.

CONCLUSION

In severely obese patients, Treg lymphocytes are clearly reduced and CD4+ effector memory cells are increased. It may be hypothesized that they might contribute to the development of marked microvascular alterations previously observed in these patients.