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ABSTRACT Objectives Methods Results Conclusions To investigate the effects of the heat shock protein 90 (HSP90) complex from oral lichen planus (OLP) lesion tissues on dendritic cell (DC) activation and the polarization of naïve T cells.Expression of HSP90 in OLP lesions and healthy control (HC) mucosa was evaluated by single‐cell RNA sequence, IHC, qRT‐PCR, and immunoblotting. HSP90 complex was extracted by immunoprecipitation from oral mucosa as the agonist of DCs. Expression of IFN‐α and MHC was detected by flow cytometry. After cocultured with pre‐stimulated DCs, polarization of naïve T cells was investigated by cytokine analysis.HSP90 was significantly higher in the lamina propria of OLP lesion and closely related to lymphocyte infiltration. HSP90 complex of OLP lesion activated DCs via TLR9 and increased their IFN‐α secretion and MHC II expression. Pre‐stimulated DCs increased the proportion of Th17 cells.HSP90 complex isolated from OLP lesion activated TLR9/IFN‐α of DCs and further promoted the polarization of naïve T cells toward Th17 immunity. [ABSTRACT FROM AUTHOR]

Thymic involution is a key factor in human immune aging, leading to reduced thymic output and a decline in recent thymic emigrant (RTE) naive T cells in circulation. Currently, the precise definition of human RTEs and their corresponding cell surface markers lacks clarity. Analysis of single-cell RNA-seq/ATAC-seq data distinguished RTEs by the expression of SOX4, IKZF2, and TOX and CD38 protein, whereby surface CD38hi expression universally identified CD8+ and CD4+ RTEs. We further determined the dynamics of RTEs and mature cells in a cohort of 158 individuals, including age-associated transcriptional reprogramming and shifts in cytokine production. Spectral cytometry profiling revealed two axes of aging common to naive CD8+ and CD4+ T cells: (1) a decrease in CD38++ cells (RTEs) and (2) an increase in CXCR3hi cells. Identification of RTEs enables direct assessment of thymic health. Furthermore, resolving the dynamics of naive T cell remodeling yields insight into vaccination and infection responsiveness throughout aging. [Display omitted] • Human RTEs are epigenetically and transcriptionally defined by SOX4, IKZF2, and TOX • Both CD8+ and CD4+ RTEs are characterized by high surface expression of CD38 • CD38 expression is a reliable RTE marker also under chronic and acute inflammation • Naive T cells show an age-related decline in CD38++ RTEs and an increase in CXCR3hi cells Identifying human T cells that have recently emigrated from the thymus remains problematic. Here, Bohacova et al. categorize recent thymic emigrants with high CD38 expression as their universal surface marker. Additionally, they explore the transcriptional and epigenetic landscape of naive CD8+ and CD4+ T cells, revealing shared axes of aging. [ABSTRACT FROM AUTHOR]

The cross-talk between the innate and adaptive immune response represents the first defense weapon against the threat of pathogens. Substantial evidence has shown a relationship between immune phenotype lymphocytes and COVID-19 disease severity and/or implication in susceptibility to SARS-CoV-2 infection. Recently, belonging to ABO blood groups has been investigated as a correlation factor to COVID-19 disease. This pilot study investigated lymphocyte typing in a cohort of blood donors to understand the underlying mechanism in SARS-CoV-2 infection linked to the blood group. The study cohort consisted of 20–64-year-old subjects, without comorbidities, from both sexes, who were COVID-19 vaccinated with previous or no infection history. Whole blood samples, collected at A.O.R.N. Sant'Anna and San Sebastiano Hospital (Campania Region), were processed by multiparametric cytofluorimetric assay, to characterize CD4+ helper and CD8+ cytotoxic T cell CD3+ subpopulations. The CD45RA, CCR7, CD27, CD28, CD57 and PD-1 markers were investigated to delineate the peripheral T-cell maturation stages. Differences were detected in ABO blood types in CD3+, CD4+ gated on CD3+, CD8+ and CD8+ gated on CD3+ percentage. These results contribute to identifying a memory cell "identikit" profile in COVID-19 disease, thus leading to a useful tool in precision medicine. [ABSTRACT FROM AUTHOR]

BACKGROUND: Genetic aberrations in the NFκB pathway lead to primary immunodeficiencies with various degrees of severity. We previously demonstrated that complete ablation of the RelB transcription factor, a key component of the alternative pathway, results in an early manifested combined immunodeficiency requiring stem cell transplantation. OBJECTIVE: To study the molecular basis of a progressive severe autoimmunity and immunodeficiency in three patients. METHODS: Whole exome sequencing was performed to identify the genetic defect. Molecular and cellular techniques were utilized to assess the variant impact on NFκB signaling, canonical and alternative pathway crosstalk, as well as the resultant effects on immune function. RESULTS: Patients presented with multiple autoimmune progressive severe manifestations encompassing the liver, gut, lung, and skin, becoming debilitating in the second decade of life. This was accompanied by a deterioration of the immune system, demonstrating an age-related decline in naïve T cells and responses to mitogens, accompanied by a gradual loss of all circulating CD19+ cells. Whole exome sequencing identified a novel homozygous c. C1091T (P364L) transition in RELB. The P364L RelB protein was unstable, with extremely low expression, but retained some function and could be transiently and partially upregulated following Toll-like receptor stimulation. Stimulation of P364L patient fibroblasts resulted in a marked rise in a cluster of pro-inflammatory hyper-expressed transcripts consistent with the removal of RelB inhibitory effect on RelA function. This is likely the main driver of autoimmune manifestations in these patients. CONCLUSION: Incomplete loss of RelB provided a unique opportunity to gain insights into NFκBs pathway interactions as well as the pathogenesis of autoimmunity. The P364L RelB mutation leads to gradual decline in immune function with progression of severe debilitating autoimmunity.

Objective To compare and analyze the differences in CD8+ naive, effector, memory, exhausted and regulatory T cells in order to investigate the impact of gender on the differentiation fate of CD8+ T cells in the context of type 1 diabetes (T1D) based on female and male non-obese diabetic (NOD) mice and healthy Institute for Cancer Research (ICR) mice. Methods The frequencies and phenotypes of CD8+ T cell differentiation subsets including naive T cells (TN), central memory T cells (TCM), effector T cells (TEFF), effector precursor T cells (TEP), exhausted T cells (TEX), precursor exhausted T cells (TPEX) and regulatory T cells (Tregs) in the spleen, pancreatic draining lymph nodes (pLN) and pancreas infiltrating lymphocytes (PIL) of male and female NOD mice were detected by flow cytometry. Results The frequencies of IFN-γ+, CD107a+ and CCL5+ CD8+ TEFF in pLN and PIL of female NOD mice were significantly higher than those of male NOD mice. However, the frequencies of CD8+ TN, CD8+ TCM, CD8+ TEX, CD8+ TPEX and CD122+CD8+ Tregs subsets in the spleen were significantly decreased. While there were no significant differences in the above CD8+ T cell subsets except CD8+ Tregs between female and male ICR mice. Conclusion Androgen may inhibit the differentiation of memory T cells into effector T cells and promote the exhaustion of effector T cells, leading to the difference in morbidity between the male and female mice.

T lymphocytes are pivotal in adaptive immunity. The role of the trafficking protein particle complex (TRAPPC) in regulating T‐cell development and homeostasis is unknown. Using CD4cre‐Trappc1flox/flox (Trappc1 cKO) mice, we found that Trappc1 deficiency in T cells significantly decreased cell number of naive T cells in the periphery, whereas thymic T‐cell development in Trappc1 cKO mice was identical as WT mice. In the culture assays and mouse models with adoptive transfer of the sorted WT (CD45.1+CD45.2+) and Trappc1 cKO naive T cells (CD45.2+) to CD45.1+ syngeneic mice, Trappc1‐deficient naive T cells showed significantly reduced survival ability compared with WT cells. RNA‐seq and molecular studies showed that Trappc1 deficiency in naive T cells reduced protein transport from the endoplasmic reticulum to the Golgi apparatus, enhanced unfolded protein responses, increased P53 transcription, intracellular Ca2+, Atf4‐CHOP, oxidative phosphorylation, and lipid peroxide accumulation, and subsequently led to ferroptosis. Trappc1 deficiency in naive T cells increased ferroptosis‐related damage‐associated molecular pattern molecules like high mobility group box 1 or lipid oxidation products like prostaglandin E2, leukotriene B4, leukotriene C4, and leukotriene D4. Functionally, the culture supernatant of Trappc1 cKO naive T cells significantly promoted neutrophils to express inflammatory cytokines like TNFα and IL‐6, which was rescued by lipid peroxidation inhibitor Acetylcysteine. Importantly, Trappc1 cKO mice spontaneously developed severe autoinflammatory disease 4 weeks after birth. Thus, intrinsic expression of Trappc1 in naive T cells plays an integral role in maintaining T‐cell homeostasis to avoid proinflammatory naive T‐cell death‐caused autoinflammatory syndrome in mice. This study highlights the importance of the TRAPPC in T‐cell biology. [ABSTRACT FROM AUTHOR]

The clinical expression of 22q11.2 deletion syndrome (22q11.2 DS) is extremely variable, as patients can present with recurrent or severe infections, immune dysregulation, atopic diseases, or extra-immunological manifestations. The immunological background underlying the different disease manifestations is not completely elucidated. The aim of this study was to identify the immunophenotypic peculiarities of 22q11.2 DS patients presenting with different disease expressions. This study included 34 patients with 22q11.2 DS, divided into three groups according to the clinical phenotype: isolated extra-immunological manifestations (G1), infectious phenotype with increased/severe infections (G2), and immune dysregulation (G3). The patients underwent extended immunophenotyping of the T and B lymphocytes and analysis of the circulating dendritic cells (DCs). In patients with an infectious phenotype, a significant reduction in CD3+ and CD4+ cells and an expansion of CD8 naïve cells was evidenced. On the other hand, the immunophenotype of the patients with immune dysregulation showed a skewing toward memory T cell populations, and reduced levels of recent thymic emigrants (RTEs), while the highest levels of RTEs were detected in the patients with isolated extra-immunological manifestations. This study integrates the current literature, contributing to elucidating the variability in the immune status of patients with 22q11.2DS with different phenotypic expressions, particularly in those with infectious phenotype and immune dysregulation. [ABSTRACT FROM AUTHOR]

Introduction: The lymphatic system has a pivotal role in immune homeostasis. To better understand this, we investigated the impact of Primary Lymphatic Anomalies (PLA) on lymphocyte numbers and phenotype. Methods: The study comprised (i) a retrospective cohort: 177 PLA subjects from the National Primary Lymphatic Anomaly Register with clinical and laboratory data, and (ii) a prospective cohort: 28 patients with PLA and 20 healthy controls. Patients were subdivided using established phenotypic diagnostic categories and grouped into simplex (localised tissue involvement only) and systemic (involvement of central lymphatics). Further grouping variables included genital involvement and the likelihood of co-existent intestinal lymphangiectasia. Haematology laboratory parameters were analysed in both cohorts. In the prospective cohort, prospective blood samples were analysed by flow cytometry for markers of proliferation, differentiation, activation, skin-homing, and for regulatory (CD4+Foxp3+) T cells (Treg). Results: In patients with PLA, lymphopaenia was frequent (22% of subjects), affected primarily the CD4+ T cell subset, and was more severe in subjects with systemic versus simplex patterns of disease (36% vs 9% for lymphopaenia; 70% vs 33% for CD4+ cells). B cells, NK cells and monocytes were better conserved (except in GATA2 deficiency characterised by monocytopaenia). Genital oedema and likelihood of concomitant intestinal lymphangiectasia independently predicted CD4+ T cell depletion. Analysing CD4+ and CD8+ T cells by differentiation markers revealed disproportionate depletion of naive cells, with a skewing towards a more differentiated effector profile. Systemic PLA conditions were associated with: increased expression of Ki67, indicative of recent cell division, in naive CD4+, but not CD8+ T cells; increased levels of activation in CD4+, but not CD8+ T cells; and an increased proportion of Treg. Skin-homing marker (CCR10, CLA and CCR4) expression was reduced in some patients with simplex phenotypes. Discussion: Patients with PLA who have dysfunctional lymphatics have a selective reduction in circulating lymphocytes which preferentially depletes naive CD4+ T cells. The presence of systemic disease, genital oedema, and intestinal lymphangiectasia independently predict CD4 lymphopaenia. The association of this depletion with immune activation and increased circulating Tregs suggests lymphatic-lymphocyte interactions and local inflammatory changes are pivotal in driving immunopathology. [ABSTRACT FROM AUTHOR]

The specificity of T cells is that each T cell has only one T cell receptor (TCR). A T cell clone represents a collection of T cells with the same TCR sequence. Thus, the number of different T cell clones in an organism reflects the number of different T cell receptors (TCRs) that arise from recombination of the V(D)J gene segments during T cell development in the thymus. TCR diversity and more specifically, the clone abundance distribution, are important factors in immune functions. Specific recombination patterns occur more frequently than others while subsequent interactions between TCRs and self-antigens are known to trigger proliferation and sustain naive T cell survival. These processes are TCR-dependent, leading to clone-dependent thymic export and naive T cell proliferation rates. We describe the heterogeneous steady-state population of naive T cells (those that have not yet been antigenically triggered) by using a mean-field model of a regulated birth-death-immigration process. After accounting for random sampling, we investigate how TCR-dependent heterogeneities in immigration and proliferation rates affect the shape of clone abundance distributions (the number of different clones that are represented by a specific number of cells, or clone counts). By using reasonable physiological parameter values and fitting predicted clone counts to experimentally sampled clone abundances, we show that realistic levels of heterogeneity in immigration rates cause very little change to predicted clone-counts, but that modest heterogeneity in proliferation rates can generate the observed clone abundances. Our analysis provides constraints among physiological parameters that are necessary to yield predictions that qualitatively match the data. Assumptions of the model and potentially other important mechanistic factors are discussed.

The dynamics of cell populations are frequently studied in vivo using pulse-chase DNA labeling techniques. When combined with mathematical models, the kinetic of label uptake and loss within a population of interest then allows one to estimate rates of cell production and turnover through death or onward differentiation. Here we explore an alternative method of quantifying cellular dynamics, using a cell fate-mapping mouse model in which dividing cells can be induced to constitutively express a fluorescent protein, using a Ki67 reporter construct. We use a pulse-chase approach with this reporter mouse system to measure the lifespans and division rates of naive CD4 and CD8 T cells using a variety of modeling approaches, and show that they are all consistent with estimates derived from other published methods. However we propose that to obtain unbiased parameter estimates and full measures of their uncertainty one should simultaneously model the timecourses of the frequencies of labeled cells within both the population of interest and its precursor. We conclude that Ki67 reporter mice provide a promising system for modeling cellular dynamics. [ABSTRACT FROM AUTHOR]

Background. Memory CD4+ T cells proliferation is the basis for accelerated secondary immune response. The characteristics of memory CD4+ T cells providing their faster division compared to naive CD4+ T lymphocytes are poorly understood. T cells proliferative ability is determined by their metabolism. The metabolic features of proliferating memory CD4+ T cells remain elusive. The aim. To compare the metabolic features of naive and memory CD4+ T cells in quiescence and during proliferation. Methods. Peripheral blood mononuclear cells were analyzed using flow cytometry. Dividing cells were identified by CD71 expression. Cellular glucose and fatty acid uptake was assessed using fluorescent glucose (2-NBDG) and palmitate (BODIPY-FL-C16) analogs, respectively. Glutamine transporter expression was analyzed by staining the cells with anti-ASCT2 antibodies. Mitochondrial mass and membrane potential were measured using MitoTracker Green and MitoTracker Orange, respectively. Results. Quiescent memory CD4+ T cells exhibited elevated levels of glucose and palmitate uptake when compared to naive CD4 + T lymphocytes (p < 0.001). Both subsets had increased substrate consumption when proceeding to proliferation (p < 0.001). When dividing, naive CD4+ T cells consumed more glucose and palmitate than memory CD4+ T cell (p < 0.001). Proliferation caused an increase in mitochondrial mass in naive (p < 0.001) and memory CD4+ T lymphocytes (p < 0.05). In memory CD4+ T cells, unlike naive CD4+ T lymphocytes, an increase in mitochondrial mass wasn’t accompanied by an increase in membrane potential. Conclusion. In memory CD4 + T cells, compared to naive CD4+ T lymphocytes, the metabolic change induced by proliferation is moderate and affects the mitochondrial activity to a lesser extent. Lower bioenergetic expenses of memory CD4+ T cells can contribute to their rapid proliferation during secondary immune response.

Naïve T cells and regulatory T cells, when purified, do not proliferate to the γc-cytokines IL-2, IL-7, or IL-15, despite their expression of cognate cytokine receptors. Dendritic cells (DCs) enabled the T cell proliferation to these cytokines, through cell-to-cell contact, but independent of T cell receptor stimulation. This effect lasted after separation of T cells from DCs, enabling enhanced proliferation of the T cells in DC-depleted hosts. We propose calling this a "preconditioning effect". Interestingly, IL-2 alone was sufficient to induce phosphorylation and nuclear translocation of STAT5 in T cells, but could not activate MAPK and AKT pathways and failed to induce transcription of IL-2 target genes. "Preconditioning" was necessary to activate these two pathways and induced weak Ca2+ mobilization independent of calcium release-activated channels. When preconditioning was combined with IL-2, full activation of downstream mTOR, 4E-BP1 hyperphosphorylation, and prolonged S6 phosphorylation occurred. Collectively, accessory cells provide T cell preconditioning, a unique activation mechanism, controlling cytokine-mediated proliferation of T cells. [ABSTRACT FROM AUTHOR]

This multiplex staining panel was developed to differentiate cattle T cells into conventional (CD4 and CD8) and unconventional (γδ‐TCR) subsets as well as their stage of differentiation and activation. The combination of CD45RO and CD62L allows the identification of naïve (TNaïve), central memory (TCM), effector memory (TEM) and terminal effector (TTE) T cells. Activated cattle T cells (TAV) can be identified by the cell surface expression of CD25. This panel was developed using cryopreserved cattle peripheral blood mononuclear cells (PBMCs) and tested on fresh as well as stimulated PBMCs. Therefore, this 8‐color, 10‐parameter flow cytometry panel simultaneously identifies cattle TNaïve, TAV, TCM, TEM, TTE and γδ‐TCR cells. This panel will improve our ability to examine T‐cell response to pathogens and vaccines in cattle including the potential to identify previously undescribed subpopulations. Furthermore, this panel can be readily optimized for other bovid species as many of these reagents are likely to cross react. [ABSTRACT FROM AUTHOR]

The dynamics of cell populations are frequently studied in vivo using pulse-chase DNA labeling techniques. When combined with mathematical models, the kinetic of label uptake and loss within a population of interest then allows one to estimate rates of cell production and turnover through death or onward differentiation. Here we explore an alternative method of quantifying cellular dynamics, using a cell fate-mapping mouse model in which dividing cells can be induced to constitutively express a fluorescent protein, using a Ki67 reporter construct. We use a pulse-chase approach with this reporter mouse system to measure the lifespans and division rates of naive CD4 and CD8 T cells using a variety of modeling approaches, and show that they are all consistent with estimates derived from other published methods. However we propose that to obtain unbiased parameter estimates and full measures of their uncertainty one should simultaneously model the timecourses of the frequencies of labeled cells within both the population of interest and its precursor. We conclude that Ki67 reporter mice provide a promising system for modeling cellular dynamics.

Disease course in sarcoidosis is highly variable. Bronchoalveolar lavage fluid and mediastinal lymph nodes show accumulation of activated T cells with a T-helper (Th)17.1 signature, which correlates with non-resolving sarcoidosis. We hypothesize that the peripheral blood (PB) T cell phenotype may correlate with outcome. To compare frequencies, phenotypes and function of circulating T cell populations in sarcoidosis patients with healthy controls (HCs) and correlate these parameters with outcome. We used multi-color flow cytometry to quantify activation marker expression on PB T cell subsets in treatment-naïve patients and HCs. The disease course was determined after 2-year follow-up. Cytokine production was measured after T cell stimulation in vitro. We observed significant differences between patients and HCs in several T cell populations, including CD8+ and CD4+ T cells, Th1/Th17 subsets, CD4+ T memory stem cells, regulatory T cells (Tregs) and γδ T cells. Decreased frequencies of CD4+ T cells and increased frequencies of Tregs and CD8+ γδ T cells correlated with worse outcome. Naïve CD4+ T cells displayed an activated phenotype with increased CD25 expression in patients with active chronic disease at 2-year follow-up. A distinctive Treg phenotype with increased expression of CD25, CTLA4, CD69, PD-1 and CD95 correlated with chronic sarcoidosis. Upon stimulation, both naïve and memory T cells displayed a different cytokine profile in sarcoidosis compared to HCs. Circulating T cell subpopulations of sarcoidosis patients display phenotypic abnormalities that correlate with disease outcome, supporting a critical role of aberrant T cell activation in sarcoidosis pathogenesis. • Disease course in sarcoidosis is highly variable and unpredictable. • The discovery of biomarkers to predict long-term disease outcome can help clinical decision making. • Peripheral T cells differ between patients and controls in frequency and phenotype. • Aberrantly activated naïve and regulatory T cells correlate with worse long-term outcome in sarcoidosis. • Stimulated naïve and memory T cells show an altered cytokine profile in sarcoidosis. [ABSTRACT FROM AUTHOR]

Background: Precursor T-cell acute lymphoblastic leukemia (Pre-T ALL) is a malignant neoplastic disease in which T-cells proliferate in the bone marrow. Single-cell sequencing technology could identify characteristic cell types, facilitating the study of the therapeutic mechanisms in Pre-T ALL., Methods: The single-cell sequencing data (scRNA-seq) of Pre-T ALL were obtained from public databases. Key immune cell subpopulations involved in the progression of Pre-T ALL were identified by clustering and annotating the cellular data using AUCell. Next, pseudo-temporal analysis was performed to identify the differentiation trajectories of immune cell subpopulations using Monocle. Copy number mutation landscape of cell subpopulations was characterized by inferCNV. Finally, cellphoneDB was used to analyze intercellular communication relationships., Results: A total of 10 cellular subpopulations were classified, with Pre-T ALL showing a higher proportion of NK/T cells. NK/T cells were further clustered into two subpopulations. Stem T cells showed a high expression of marker genes related to hematopoietic stem cells, Naive T cells had a high expression of CCR7, CCR7, RCAN3, and NK cells high-expressed KLRD1, TRDC. The cell proliferation was reduced and the activation of T cell was increased during the differentiation of stem T cells to Naive T cells. We observed interaction between stem T cells with dendritic cells such as CD74-COPA, CD74-MIF as well as co-inhibition-related interactions such as LGALS9-HAVCR2, TGFB1-TGFBR3., Conclusion: Stem T cells were involved in the development of Pre-T-ALL through the regulatory effects of transcription factors (TFs) KLF2 and FOS and multiple ligand-receptor pairs.

A breakdown in cellular homeostasis is thought to drive naïve T cell aging, however the link between naïve T cell homeostasis and aging in humans is poorly understood. To better address this, we developed a lymphoid organoid system that maintains resting naïve T cells for more than 2 weeks, in conjunction with high CD45RA expression. Deep phenotypic characterization of naïve T cells across age identified reduced CD45RA density as a hallmark of aging. A conversion from CD45RAhigh naive cells to a CD45RAlow phenotype was reproduced within our organoid system by structural breakdown, but not by stromal cell aging or reduced lymphocyte density, and mediated by alternative CD45 splicing. Together, these data suggest that external influences within the lymph node microenvironment may cause phenotypic conversion of naïve T cells in older adults.

Post-thymic naïve T cells constitute a key cellular arm of adaptive immunity, with a well-known characteristic of the specificity and robustness of responses to cognate foreign antigens which is presented as a form of antigen-derived peptides bound to major histocompatibility complex (MHC) molecules by antigen-presenting cells (APCs). In a steady state, however, these cells are resting, quiescent in their activity, but must keep full ranges of functional integrity to mount rapid and robust immunity to cope with various infectious pathogens at any time and space. Such unique property of resting naïve T cells is not acquired in a default manner but rather requires an active mechanism. Although our understanding of exactly how this process occurs and what factors are involved remains incomplete, a particular role of self-recognition by T cells has grown greatly in recent years. In this brief review, we discuss recent data on how the interaction of T cells with self-peptide MHC ligands regulates their functional responsiveness and propose that variable strength of self-reactivity imposes distinctly different levels of functional competence and heterogeneity.

Mathematical models encoding biological hypotheses reveal new insight into the dynamics of naive immune cells in mice from birth to old age.

The outcome of allogeneic hematopoietic cell transplantation (allo-HCT) largely depends on the development and management of graft-versus-host disease (GvHD), infections, and the occurrence of relapse of malignancies. Recent studies showed a lower incidence of chronic GvHD and severe acute GvHD in patients receiving naive T cell depleted grafts compared to patients receiving complete T cell depleted grafts. On the other hand, the incidence of acute GvHD in patients receiving cord blood grafts containing only naive T cells is rather low, while potent graft-versus-leukemia (GvL) responses have been observed. These data suggest the significance of naive T cells as both drivers and regulators of allogeneic reactions. The naive T cell pool was previously thought to be a quiescent, homogenous pool of antigen-inexperienced cells. However, recent studies showed important differences in phenotype, differentiation status, location, and function within the naive T cell population. Therefore, the adequate recovery of these seemingly innocent T cells might be relevant in the imminent allogeneic reactions after allo-HCT. Here, an extensive review on naive T cells and their contribution to the development of GvHD and GvL responses after allo-HCT is provided. In addition, strategies specifically directed to stimulate adequate reconstitution of naive T cells while reducing the risk of GvHD are discussed. A better understanding of the relation between naive T cells and alloreactivity after allo-HCT could provide opportunities to improve GvHD prevention, while maintaining GvL effects to lower relapse risk. [ABSTRACT FROM AUTHOR]

T‐bet is the lineage‐specifying transcription factor for CD4+ TH1 cells. T‐bet has also been found in other CD4+ T cell subsets, including TH17 cells and Treg, where it modulates their functional characteristics. However, we lack information on when and where T‐bet is expressed during T cell differentiation and how this impacts T cell differentiation and function. To address this, we traced the ontogeny of T‐bet‐expressing cells using a fluorescent fate‐mapping mouse line. We demonstrate that T‐bet is expressed in a subset of CD4+ T cells that have naïve cell surface markers and transcriptional profile and that this novel cell population is phenotypically and functionally distinct from previously described populations of naïve and memory CD4+ T cells. Naïve‐like T‐bet‐experienced cells are polarized to the TH1 lineage, predisposed to produce IFN‐γ upon cell activation, and resist repolarization to other lineages in vitro and in vivo. These results demonstrate that lineage‐specifying factors can polarize T cells in the absence of canonical markers of T cell activation and that this has an impact on the subsequent T‐helper response. [ABSTRACT FROM AUTHOR]

The outcome of allogeneic hematopoietic cell transplantation (allo-HCT) largely depends on the development and management of graft-versus-host disease (GvHD), infections, and the occurrence of relapse of malignancies. Recent studies showed a lower incidence of chronic GvHD and severe acute GvHD in patients receiving naive T cell depleted grafts compared to patients receiving complete T cell depleted grafts. On the other hand, the incidence of acute GvHD in patients receiving cord blood grafts containing only naive T cells is rather low, while potent graft-versus-leukemia (GvL) responses have been observed. These data suggest the significance of naive T cells as both drivers and regulators of allogeneic reactions. The naive T cell pool was previously thought to be a quiescent, homogenous pool of antigen-inexperienced cells. However, recent studies showed important differences in phenotype, differentiation status, location, and function within the naive T cell population. Therefore, the adequate recovery of these seemingly innocent T cells might be relevant in the imminent allogeneic reactions after allo-HCT. Here, an extensive review on naive T cells and their contribution to the development of GvHD and GvL responses after allo-HCT is provided. In addition, strategies specifically directed to stimulate adequate reconstitution of naive T cells while reducing the risk of GvHD are discussed. A better understanding of the relation between naive T cells and alloreactivity after allo-HCT could provide opportunities to improve GvHD prevention, while maintaining GvL effects to lower relapse risk.

Naive CD4 and CD8 T cells are cornerstones of adaptive immunity, but the dynamics of their establishment early in life and how their kinetics change as they mature following release from the thymus are poorly understood. Further, due to the diverse signals implicated in naive T cell survival, it has been a long-held and conceptually attractive view that they are sustained by active homeostatic control as thymic activity wanes. Here we use multiple modelling and experimental approaches to identify a unified model of naive CD4 and CD8 T cell population dynamics in mice, across their lifespan. We infer that both subsets divide rarely, and progressively increase their survival capacity with cell age. Strikingly, this simple model is able to describe naive CD4 T cell dynamics throughout life. In contrast, we find that newly generated naive CD8 T cells are lost more rapidly during the first 3–4 weeks of life, likely due to increased recruitment into memory. We find no evidence for elevated division rates in neonates, or for feedback regulation of naive T cell numbers at any age. We show how confronting mathematical models with diverse datasets can reveal a quantitative and remarkably simple picture of naive T cell dynamics in mice from birth into old age.

The specificity of T cells is that each T cell has only one T cell receptor (TCR). A T cell clone represents a collection of T cells with the same TCR sequence. Thus, the number of different T cell clones in an organism reflects the number of different T cell receptors (TCRs) that arise from recombination of the V(D)J gene segments during T cell development in the thymus. TCR diversity and more specifically, the clone abundance distribution, are important factors in immune functions. Specific recombination patterns occur more frequently than others while subsequent interactions between TCRs and self-antigens are known to trigger proliferation and sustain naive T cell survival. These processes are TCR-dependent, leading to clone-dependent thymic export and naive T cell proliferation rates. We describe the heterogeneous steady-state population of naive T cells (those that have not yet been antigenically triggered) by using a mean-field model of a regulated birth-death-immigration process. After accounting for random sampling, we investigate how TCR-dependent heterogeneities in immigration and proliferation rates affect the shape of clone abundance distributions (the number of different clones that are represented by a specific number of cells, or "clone counts"). By using reasonable physiological parameter values and fitting predicted clone counts to experimentally sampled clone abundances, we show that realistic levels of heterogeneity in immigration rates cause very little change to predicted clone-counts, but that modest heterogeneity in proliferation rates can generate the observed clone abundances. Our analysis provides constraints among physiological parameters that are necessary to yield predictions that qualitatively match the data. Assumptions of the model and potentially other important mechanistic factors are discussed. [ABSTRACT FROM AUTHOR]

Adoptive cellular therapy using chimeric antigen receptors (CARs) has revolutionized our treatment of relapsed B cell malignancies and is currently being integrated into standard therapy. The impact of selecting specific T cell subsets for CAR transduction remains under investigation. Previous studies demonstrated that effector T cells derived from naive, rather than central memory T cells mediate more potent antitumor effects. Here, we investigate a method to skew CAR transduction toward naive T cells without physical cell sorting. Viral-mediated CAR transduction requires ex vivo T cell activation, traditionally achieved using antibody-mediated strategies. CD81 is a T cell costimulatory molecule that when combined with CD3 and CD28 enhances naive T cell activation. We interrogate the effect of CD81 costimulation on resultant CAR transduction. We identify that upon CD81-mediated activation, naive T cells lose their identifying surface phenotype and switch to a memory phenotype. By prelabeling naive T cells and tracking them through T cell activation and CAR transduction, we document that CD81 costimulation enhanced naive T cell activation and resultantly generated a CAR T cell product enriched with naive-derived CAR T cells. [ABSTRACT FROM AUTHOR]

Lung cancer is the second cause of cancer related deaths worldwide. Chemotherapy and immunotherapy represent the current standard of care for advanced NSCLC. Platinum-based chemotherapy expands late-differentiated T cell populations. Therefore, immune restoration after chemotherapy to adjuvate the immunotherapeutic potential could be crucial. The aim of this study was to evaluate the effect of Biomodulina T (BT), a thymic polypeptide fraction, on peripheral lymphocytes subpopulations in the context of cancer disease. Additionally, whether these effects might induce a better response to CIMAvax-EGF, an epidermal growth factor (EGF) depleting immunotherapy. Eighteen advanced NSCLC patients were evaluated after being treated with platinum-based chemotherapy. We found that the frequency of terminally differentiated effector T cells re-expressing CD45RA (EMRA) CD4+ (p=0.0031) and CD8+ (p=0.0372) T cells decreased with the administration of BT, whereas CD4+ naive T cells increase in more than 70% of the patients. Remarkably, CD4+ and CD8+ T lymphocytes expressing programmed cell death receptor-1 (PD1) significantly decreased after BT administration (p=0.0005 and p<0.0001, respectively). We also found an enhancement of the anti-EGF antibody response with a large percentage of patients treated with CIMAvax-EGF reaching the good antibody response condition after four vaccine doses. Moreover, the median overall survival of patients treated with CIMAvax-EGF was 16.09 months. In conclusion, our results suggest that the immunorestoration generated by the administration of BT after first-line chemotherapy may induce a better immune response to CIMAvax-EGF that could translate into the clinical benefit of patients diagnosed with advanced NSCLC. [ABSTRACT FROM AUTHOR]

Introduction: Sambucus is a genus of the Adoxaceae family and has been widely used as a food and medicinal source. In this study, we aimed to evaluate the effects of S. javanica extracts toward T cells regulation in the 7,12-dimethylbenzene (a) anthracene (DMBA)-exposed mice. Methods: Thirty mice were used in this experiment which divided into six treatment groups and five times repetition. Three-month-old BALB/c mice were administrated with 2.8 mg.kg-1 BW of DMBA as carcinogen agent for ten times within four weeks, then continuously treated with 400 and 800 mg.kg-1 BW of S. javanica berries leaves extracts daily for two weeks. Treatment groups in this study were vehicle as negative control, DMBA 2.8 mg.kg-1 BW as positive control; BD1 group, DMBA 2.8 mg.kg-1 + berries extracts 400 mg.kg-1 BW; BD2 group, DMBA 2.8 mg.kg-1 + berries extracts 800 mg.kg-1 BW; LD1 group, DMBA 2.8 mg.kg-1 + leaves extract 400 mg.kg1 BW; and LD2 group, DMBA 2.8 mg.kg-1 + leaves extract 800 mg.kg-1 BW. The relative number of CD4+CD25+CD62L+ cells and CD4+CD62L+ cells were measured and analyzed by using flow cytometer. Results: DMBA induction decreased the relative number of CD4+CD25+CD62L+ cells while the leaves extract of S. javanica significantly increased their expression. Furthermore, DMBA promoted the relative number of CD4+CD62L+ cells expression while leaves and berries extracts of S. javanica sharply suppressed its expression. Conclusion: The results suggest that, S. javanica extracts may exert their medicinal properties by modulating T cells regulation in DMBA-induced mice.

Abstract Background Patients with end-stage renal disease (ESRD) exhibit a premature aging phenotype of immune system, which is recently concerned as a significant factor for increased risk of various morbidities. Nevertheless, there are few dates explicating the relevancy of T cell senescence to mortality. In this study, we prospectively studied the predictive value of T cell senescence for mortality in hemodialysis patients. Methods Patients who had been on hemodialysis treatment for at least 6 months were enrolled. T cell senescence determined by differentiation status was evaluated by flow cytometry. Survival outcomes were estimated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to evaluate the prognostic impact of T cell premature aging and other clinical factors on all-cause mortality. Results A total of 466 patients (277 man and 169 women) were enrolled in this study. Decreased number of naïve T cell, as the most prominent feature of T cell senescence, did not change in parallel with age in these patients. Decreased absolute count of T cell, naïve T cell, CD4+ naïve T cell were independently associated with all-cause mortality. Decreased percentage of T cell and increased percentage of CD8+central-memory T cell were also independently associated with all-cause mortality. After including all the T cell parameters in one regression model, only decreased count of naïve T cell was significantly associated with increased mortality in these patients. Conclusions Aging-associated T cell changes are aggravated in ESRD patients. For the first time, our study demonstrates that naïve T cell depletion is a strong predictor of all-cause mortality in HD patients.

Abstract Background End-stage renal disease is associated with premature ageing of the T cell immune system but inter-individual variation is substantial. The hypothesis was tested that advanced immunological T cell ageing assessed by peripheral T cell differentiation increases the long-term mortality risk after renal transplantation. Results Circulating T cells of 211 recipients of a kidney from a living donor were analyzed before and in the first year after transplantation. The number of CD31-positive naive T cells (as a marker for recent thymic emigrants) and the differentiation status of the memory T cells was assessed. Thirty recipients died during follow-up of at least 5 years. Absolute numbers of naive CD4+ (living:258 cells/μl vs. deceased:101 cells/μl, p

The specificity of T cells is that each T cell has only one T cell receptor (TCR). A T cell clone represents a collection of T cells with the same TCR sequence. Thus, the number of different T cell clones in an organism reflects the number of different T cell receptors (TCRs) that arise from recombination of the V(D)J gene segments during T cell development in the thymus. TCR diversity and more specifically, the clone abundance distribution, are important factors in immune functions. Specific recombination patterns occur more frequently than others while subsequent interactions between TCRs and self-antigens are known to trigger proliferation and sustain naive T cell survival. These processes are TCR-dependent, leading to clone-dependent thymic export and naive T cell proliferation rates. We describe the heterogeneous steady-state population of naive T cells (those that have not yet been antigenically triggered) by using a mean-field model of a regulated birth-death-immigration process. After accounting for random sampling, we investigate how TCR-dependent heterogeneities in immigration and proliferation rates affect the shape of clone abundance distributions (the number of different clones that are represented by a specific number of cells, or “clone counts”). By using reasonable physiological parameter values and fitting predicted clone counts to experimentally sampled clone abundances, we show that realistic levels of heterogeneity in immigration rates cause very little change to predicted clone-counts, but that modest heterogeneity in proliferation rates can generate the observed clone abundances. Our analysis provides constraints among physiological parameters that are necessary to yield predictions that qualitatively match the data. Assumptions of the model and potentially other important mechanistic factors are discussed.

The decreased proportion of antigen-inexperienced, naïve T cells is a hallmark of aging in both humans and mice, and contributes to reduced immune responses, particularly against novel and re-emerging pathogens. Naïve T cells depend on survival signals received during their circulation among the lymph nodes by direct contacts with stroma, in particular fibroblastic reticular cells. Macroscopic changes to the architecture of the lymph nodes have been described, but it is unclear how lymph node stroma are altered with age, and whether these changes contribute to reduced naïve T cell maintenance. Here, using 2-photon microscopy, we determined that the aged lymph node displayed increased fibrosis and correspondingly, that naïve T-cell motility was impaired in the aged lymph node, especially in proximity to fibrotic deposition. Functionally, adoptively transferred young naïve T-cells exhibited reduced homeostatic turnover in aged hosts, supporting the role of T cell-extrinsic mechanisms that regulate their survival. Further, we determined that early development of resident fibroblastic reticular cells was impaired, which may correlate to the declining levels of naïve T-cell homeostatic factors observed in aged lymph nodes. Thus, our study addresses the controversy as to whether aging impacts the composition lymph node stroma and supports a model in which impaired differentiation of lymph node fibroblasts and increased fibrosis inhibits the interactions necessary for naïve T cell homeostasis.

Lung cancer is the second cause of cancer related deaths worldwide. Chemotherapy and immunotherapy represent the current standard of care for advanced NSCLC. Platinum-based chemotherapy expands late-differentiated T cell populations. Therefore, immune restoration after chemotherapy to adjuvate the immunotherapeutic potential could be crucial. The aim of this study was to evaluate the effect of Biomodulina T (BT), a thymic polypeptide fraction, on peripheral lymphocytes subpopulations in the context of cancer disease. Additionally, whether these effects might induce a better response to CIMAvax-EGF, an epidermal growth factor (EGF) depleting immunotherapy. Eighteen advanced NSCLC patients were evaluated after being treated with platinum-based chemotherapy. We found that the frequency of terminally differentiated effector T cells re-expressing CD45RA (EMRA) CD4+ (p=0.0031) and CD8+ (p=0.0372) T cells decreased with the administration of BT, whereas CD4+ naive T cells increase in more than 70% of the patients. Remarkably, CD4+ and CD8+ T lymphocytes expressing programmed cell death receptor-1 (PD1) significantly decreased after BT administration (p=0.0005 and p

Primary sclerosing cholangitis (PSC) is an immune-mediated liver disease of unknown pathogenesis, with a high risk to develop cirrhosis and malignancies. Functional dysregulation of T cells and association with genetic polymorphisms in T cell-related genes were previously reported for PSC. Here, we genotyped a representative PSC cohort for several disease-associated risk loci and identified rs56258221 (BACH2/MIR4464) to correlate with not only the peripheral blood T cell immunophenotype but also the functional capacities of naive CD4 + T (CD4 + T N ) cells in people with PSC. Mechanistically, rs56258221 leads to an increased expression of miR4464, in turn causing attenuated translation of BACH2, a major gatekeeper of T cell quiescence. Thereby, the fate of CD4 + T N is skewed toward polarization into pro-inflammatory subsets. Clinically, people with PSC carrying rs56258221 show signs of accelerated disease progression. The data presented here highlight the importance of assigning functional outcomes to disease-associated genetic polymorphisms as potential drivers of diseases., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

We studied the effects of pregnancy-specific β1-glycoprotein (PSG) on the replicative potential of naïve T cells (CD45RA+) and immune memory T cells (CD45R0+) in vitro by evaluating the expression of the hTERT gene in combination with the proliferative activity of cells. Human PSG was obtained by the author's patented method of immunopurification using a biospecific sorbent with subsequent removal of immunoglobulin contamination on a HiTrap Protein G HP column. We used monocultures of CD45RA+ and CD45R0+ lymphocytes isolated from peripheral blood mononuclear cells of reproductive-age women. It was found that PSG in physiological concentrations inhibited the expression of the hTERT gene mRNA in naïve T cells and immune memory T cells and simultaneously reduced the number of proliferating T cells estimated by the differential gating method. At the same time, PSG reduced CD71 expression only on naïve T cells without affecting this molecule on immune memory T cells. Thus, PSG decreased the replication potential and suppressed the proliferation of T cells and immune memory T cells, which in the context of pregnancy can contribute to the formation of immune tolerance to the semi-allogeneic embryo. [ABSTRACT FROM AUTHOR]

Advanced age is associated with severe symptoms and death upon SARS-CoV-2 infection. Virus-specific CD8+ T-cell responses have shown to be protective toward critical COVID-19 manifestations, suggesting that suboptimal cellular immunity may contribute to the age-pattern of the disease. The induction of a CD8+ T-cell response against an emerging pathogen like SARS-CoV-2 relies on the activation of naive T cells. To investigate whether the primary CD8+ T-cell response against this virus is defective in advanced age, we used an in vitro approach to prime SARS-CoV-2-specific naive CD8+ T cells from healthy, unexposed donors of different age groups. Compared to younger adults, older individuals display a poor SARS-CoV-2-specific T-cell priming capacity in terms of both magnitude and quality of the response. In addition, older subjects recognize a lower number of epitopes. Our results implicate that immune aging is associated with altered primary SARS-CoV-2-specific CD8+ T-cell responses.

Circulating T helper cells with a type 17-polarized phenotype (TH17) and expansion of aquaporin-4 (AQP4)-specific T cells are frequently observed in patients with neuromyelitis optica spectrum disorder (NMOSD). However, naive T cell populations, which give rise to T helper cells, and the primary site of T cell maturation, namely the thymus, have not been studied in these patients. Here, we report the alterations of naive CD4 T cell homeostasis and the changes in thymic characteristics in NMOSD patients. Flow cytometry was performed to investigate the naive CD4+ T cell subpopulations in 44 NMOSD patients and 21 healthy controls (HC). On immunological evaluation, NMOSD patients exhibited increased counts of CD31+thymic naive CD4+ T cells and CD31-cental naive CD4+ T cells along with significantly higher fraction and absolute counts of peripheral blood CD45RA+ CD62L+ naive CD4+ T cells. Chest computed tomography (CT) images of 60 NMOSD patients and 65 HCs were retrospectively reviewed to characterize the thymus in NMOSD. Thymus gland of NMOSD patients exhibited unique morphological characteristics with respect to size, shape, and density. NMOSD patients showed exacerbated age-dependent thymus involution than HC, which showed a significant association with disease duration. These findings broaden our understanding of the immunological mechanisms that drive severe disease in NMOSD.

Functional HIV-1-specific CD8+ T cells primed from naive T cells are expected to act as effector T cells in a "shock-and-kill" therapeutic strategy for an HIV-1 cure since less functional HIV-1-specific CD8+ T cells are elicited from memory T cells in HIV-1-infected individuals on combined antiretroviral therapy (cART). CD8+ T cells specific for HIV-1 conserved and protective epitopes are candidates for such T cells. We investigated the priming with STING ligand of CD8+ T cells specific for HLA-B*52:01 or HLA-C*12:02-restricted protective epitopes from naive T cells. STING ligand 3939-cGAMP effectively primed CD8+ T cells specific for 3 of 4 HLA-B*52:01-restricted epitopes but failed to prime those specific for all 3 HLA-C*12:02-restricted epitopes from the naive T cells of HIV-1-uninfected individuals having an HLA-B*52:01-C*12:02 protective haplotype. These HLA-B*52:01-restricted CD8+ T cells had a strong ability to suppress HIV-1 replication and expressed a high level of cytolytic effector molecules. The viral suppression ability of these T cells was significantly correlated with the expression level of perforin and showed a trend for a positive correlation with the expression level of CD107a. The present study highlighted the priming with STING ligand of functional CD8+ T cells specific for protective epitopes, which T cells would contribute as effector T cells to a shock-and-kill therapy. [ABSTRACT FROM AUTHOR]

Little is known about the composition of intrahepatic immune cells and their contribution to the pathogenesis of primary sclerosing cholangitis (PSC). Herein, we aimed to create an atlas of intrahepatic T cells and thereby perform an in-depth characterization of T cells in inflamed human liver. Different single-cell RNA sequencing methods were combined with in silico analyses on intrahepatic and peripheral T cells from patients with PSC (n = 11) and healthy donors (HDs, n = 4). Multi-parameter flow cytometry and functional in vitro experiments were conducted on samples from patients with PSC (n = 24), controls with other liver diseases and HDs. We identified a population of intrahepatic naive-like CD4+ T cells, which was present in all liver diseases tested, but particularly expanded in PSC. This population had a transcriptome and T cell receptor repertoire similar to circulating naive T cells but expressed a set of genes associated with tissue residency. Their periductal location supported the concept of tissue-resident naive-like T cells in livers of patients with PSC. Trajectory inference suggested that these cells had the developmental propensity to acquire a T helper 17 (T H 17) polarization state. Functional and chromatin accessibility experiments revealed that circulating naive T cells in patients with PSC were predisposed to polarize towards T H 17 cells. We report the first atlas of intrahepatic T cells in PSC, which led to the identification of a previously unrecognized population of tissue-resident naive-like T cells in the inflamed human liver and to the finding that naive CD4+ T cells in PSC harbour the propensity to develop into T H 17 cells. The composition of intrahepatic immune cells in primary sclerosing cholangitis (PSC) and their contribution to disease pathogenesis is widely unknown. We analysed intrahepatic T cells and identified a previously uncharacterized population of liver-resident CD4+ T cells which are expanded in the livers of patients with PSC compared to healthy liver tissue and other liver diseases. These cells are likely to contribute to the pathogenesis of PSC and could be targeted in novel therapeutic approaches. [Display omitted] • First single-cell atlas of intrahepatic T cell landscape in PSC. • Identification of tissue-resident naive-like CD4+ T cells in human liver which are expanded in livers of patients with PSC. • Trajectory inference suggested a developmental propensity of these cells to acquire a T H 17 polarization state. • Functional experiments, using circulating naive CD4+ T cells, support the inferred propensity to acquire a T H 17 polarization state. • Chromatin accessibility studies revealed imprinting of naive CD4+ T cells towards effector function in PSC. [ABSTRACT FROM AUTHOR]

Circulating T helper cells with a type 17-polarized phenotype (TH17) and expansion of aquaporin-4 (AQP4)-specific T cells are frequently observed in patients with neuromyelitis optica spectrum disorder (NMOSD). However, naive T cell populations, which give rise to T helper cells, and the primary site of T cell maturation, namely the thymus, have not been studied in these patients. Here, we report the alterations of naive CD4 T cell homeostasis and the changes in thymic characteristics in NMOSD patients. Flow cytometry was performed to investigate the naive CD4+ T cell subpopulations in 44 NMOSD patients and 21 healthy controls (HC). On immunological evaluation, NMOSD patients exhibited increased counts of CD31+thymic naive CD4+ T cells and CD31-cental naive CD4+ T cells along with significantly higher fraction and absolute counts of peripheral blood CD45RA+ CD62L+ naive CD4+ T cells. Chest computed tomography (CT) images of 60 NMOSD patients and 65 HCs were retrospectively reviewed to characterize the thymus in NMOSD. Thymus gland of NMOSD patients exhibited unique morphological characteristics with respect to size, shape, and density. NMOSD patients showed exacerbated age-dependent thymus involution than HC, which showed a significant association with disease duration. These findings broaden our understanding of the immunological mechanisms that drive severe disease in NMOSD. [ABSTRACT FROM AUTHOR]

Advanced age is associated with severe symptoms and death upon SARS-CoV-2 infection. Virus-specific CD8+ T-cell responses have shown to be protective toward critical COVID-19 manifestations, suggesting that suboptimal cellular immunity may contribute to the age-pattern of the disease. The induction of a CD8+ T-cell response against an emerging pathogen like SARS-CoV-2 relies on the activation of naive T cells. To investigate whether the primary CD8+ T-cell response against this virus is defective in advanced age, we used an in vitro approach to prime SARS-CoV-2-specific naive CD8+ T cells from healthy, unexposed donors of different age groups. Compared to younger adults, older individuals display a poor SARS-CoV-2-specific T-cell priming capacity in terms of both magnitude and quality of the response. In addition, older subjects recognize a lower number of epitopes. Our results implicate that immune aging is associated with altered primary SARS-CoV-2-specific CD8+ T-cell responses. [ABSTRACT FROM AUTHOR]

Abstract Background Echovirus 30 (E-30) is one of the most frequently isolated pathogens in aseptic meningitis worldwide. To gain access to the central nervous system (CNS), E-30 and immune cells have to cross one of the two main barriers of the CNS, the epithelial blood–cerebrospinal fluid barrier (BCSFB) or the endothelial blood–brain barrier (BBB). In an in vitro model of the BCSFB, it has been shown that E-30 can infect human immortalized brain choroid plexus papilloma (HIBCPP) cells. Methods In this study we investigated the migration of different T cell subpopulations, naive and effector T cells, through HIBCPP cells during E-30 infection. Effects of E-30 infection and the migration process were evaluated via immunofluorescence and flow cytometry analysis, as well as transepithelial resistance and dextran flux measurement. Results Th1 effector cells and enterovirus-specific effector T cells migrated through HIBCPP cells more efficiently than naive CD4+ T cells following E-30 infection of HIBCPP cells. Among the different naive T cell populations, CD8+ T cells crossed the E-30-infected HIBCPP cell layer in a significantly higher number than CD4+ T cells. A large amount of effector T cells also remained attached to the basolateral side of the HIBCPP cells compared with naive T cells. Analysis of HIBCPP barrier function showed significant alteration after E-30 infection and trans- as well as paracellular migration of T cells independent of the respective subpopulation. Morphologic analysis of migrating T cells revealed that a polarized phenotype was induced by the chemokine CXCL12, but reversed to a round phenotype after E-30 infection. Further characterization of migrating Th1 effector cells revealed a downregulation of surface adhesion proteins such as LFA-1 PSGL-1, CD44, and CD49d. Conclusion Taken together these results suggest that naive CD8+ and Th1 effector cells are highly efficient to migrate through the BCSFB in an inflammatory environment. The T cell phenotype is modified during the migration process through HIBCPP cells.

Abstract Background Considering the effect of smoking on tumor immunity, we attempted to investigate the impact of smoking history on the prognostic value of circulating naïve and memory CD4+ and CD8+ T cells in advanced non-small cell lung cancer (NSCLC) treated with chemo(radio)therapy. Methods Of 196 histologically confirmed advanced NSCLC, 98 eligible ones were enrolled. Naïve and memory CD4+ and CD8+ T cells from peripheral blood were measured by flow cytometry. Kaplan–Meier curves helped estimate patients’ survival. The uni- and multivariate Cox proportional hazards regression model was employed in the assessment of the prognostic value of factors. Results Multivariate survival analyses showed that peripheral naïve CD4+ T cells independently predicted favorable overall survival (OS) in ever smokers with advanced NSCLC (P = 0.007), but unfavorable OS in never smokers with the same ailment (P = 0.012). Ever smokers presented a different distribution of naïve and memory T cells: low expression levels of naïve CD4+ T (P = 0.005), naïve CD8+ T (P = 0.031), CD4+ naïve/memory ratio (P = 0.020), and CD8+ naïve/memory ratio (P = 0.019), and high distributions of memory CD4 + T (P = 0.004), memory CD8 + T (P = 0.034), and naïve CD8/CD4 ratio (P = 0.020), when compared to never smokers. Conclusions We revealed the impact of cigarette-smoking on peripheral naïve CD4+ T cells’ prognostic value in advanced NSCLC patients. These results could help in refining personalized treatment for advanced NSCLC patients.

Bronchial asthma is a chronic inflammatory disease of the respiratory tract. T-lymphocytes play a key role in pathogenesis of this allergic disease. The reduction in number of naïve T cells and the accumulation of memory T cells in bronchial asthma are accompanied by dysregulation of T lymphocyte function. In present study, we have investigated the contents of different T lymphocyte subpopulations in peripheral blood as well as in resting and PHA-stimulated cultures, along with their proliferative capacity in patients with bronchial asthma and healthy donors. The study included 10 patients with bronchial asthma (age 45.4±11.8 years). One-half of patients was in remission state, the others having been at the stage of clinical exacerbation. The group of donors was formed by healthy individuals matched by gender and age to the patients. Based on expression of cell surface markers CD45R0, CD62L and CD197 (CCR7), the CD4+ and CD8+T lymphocytes were divided into central (Tcm) and effector memory cells (Tem), naïve T lymphocytes (Tnaïve) and terminally differentiated effector cells (Temra) using flow cytometry technique. The proliferative activity of Tcm, Tem and Tnaïve was evaluated in response to PHA as a functional marker of T cells. We have found that the percentage of peripheral CD4+TemCD62L+ and CD8+TemCD62L+ cells in the patients with asthma exacerbation was significantly reduced, if compared to the donors. Following PHA stimulation, these differences in T cell subsets between the groups of patients and donors were not detectable. We performed a correlation analysis between the memory T cell contents and age of the subjects studied. It was shown that the relative amounts of CD4+ and CD8+ memory cells increased with age in asthmatics, but not in healthy donors. Analysis of mitogen-induced proliferation showed that Tcm and Tnaïve cells proliferated more actively than other subpopulations in both groups. Meanwhile, the proliferative activity of CD4+T lymphocytes and subsets of CD8+Tcm, CD4+Tcm and CD4+Tem62L was higher in the group of asthma patients in remission state than in the patients with exacerbating disease, and healthy donors. The revealed increase in the relative number of memory T cells with age suggests that these cells participate in development of bronchial asthma. Proliferative response of the studied subpopulations, which was comparable to the donor values, suggests a functional maintenance of memory T cells and naïve T lymphocytes in bronchial asthma. The increased proliferation of some T-cell subpopulations in asthmatics in remission suggests an activated state of memory T cells. The observed decrease in the number of CD4+TemCD62L+ and CD8+TemCD62L+ in patients with asthma exacerbation may be, by our opinion, associated with an active inflammatory process in the airways.

Allergic reactions to drugs and chemicals are mediated by an adaptive immune response involving specific T cells. During thymic selection, T cells that have not yet encountered their cognate antigen are considered naive T cells. Due to the artificial nature of drug/chemical-T-cell epitopes, it is not clear whether thymic selection of drug/chemical-specific T cells is a common phenomenon or remains limited to few donors or simply does not exist, suggesting T-cell receptor (TCR) cross-reactivity with other antigens. Selection of drug/chemical-specific T cells could be a relatively rare event accounting for the low occurrence of drug allergy. On the other hand, a large T-cell repertoire found in multiple donors would underline the potential of a drug/chemical to be recognized by many donors. Recent observations raise the hypothesis that not only the drug/chemical, but also parts of the haptenated protein or peptides may constitute the important structural determinants for antigen recognition by the TCR. These observations may also suggest that in the case of drug/chemical allergy, the T-cell repertoire results from particular properties of certain TCR to recognize hapten-modified peptides without need for previous thymic selection. The aim of this review is to address the existence and the role of a naive T-cell repertoire in drug and chemical allergy. Understanding this role has the potential to reveal efficient strategies not only for allergy diagnosis but also for prediction of the immunogenic potential of new chemicals.

Chimeric antigen receptor (CAR)-T cell therapy has become an important method for the treatment of hematological tumors. Lentiviruses are commonly used gene transfer vectors for preparing CAR-T cells, and the conditions for preparing CAR-T cells vary greatly. This study reported for the first time the influence of differences in infection temperature on the phenotype and function of produced CAR-T cells. Our results show that infection at 4 degrees produces the highest CAR-positive rate of T cells, infection at 37 degrees produces the fastest proliferation in CAR-T cells, and infection at 32 degrees produces CAR-T cells with the greatest proportion of naive cells and the lowest expression of immune checkpoints. Therefore, infection at 32 degrees is recommended to prepare CAR-T cells. CAR-T cells derived from infection at 32 degrees seem to have a balance between function and phenotype. Importantly, they have increased oncolytic ability. This research will help optimize the generation of CAR-T cells and improve the quality of CAR-T cell products.

Allergic reactions to drugs and chemicals are mediated by an adaptive immune response involving specific T cells. During thymic selection, T cells that have not yet encountered their cognate antigen are considered naive T cells. Due to the artificial nature of drug/chemical-T-cell epitopes, it is not clear whether thymic selection of drug/chemical-specific T cells is a common phenomenon or remains limited to few donors or simply does not exist, suggesting T-cell receptor (TCR) cross-reactivity with other antigens. Selection of drug/chemical-specific T cells could be a relatively rare event accounting for the low occurrence of drug allergy. On the other hand, a large T-cell repertoire found in multiple donors would underline the potential of a drug/chemical to be recognized by many donors. Recent observations raise the hypothesis that not only the drug/chemical, but also parts of the haptenated protein or peptides may constitute the important structural determinants for antigen recognition by the TCR. These observations may also suggest that in the case of drug/chemical allergy, the T-cell repertoire results from particular properties of certain TCR to recognize hapten-modified peptides without need for previous thymic selection. The aim of this review is to address the existence and the role of a naive T-cell repertoire in drug and chemical allergy. Understanding this role has the potential to reveal efficient strategies not only for allergy diagnosis but also for prediction of the immunogenic potential of new chemicals. [ABSTRACT FROM AUTHOR]

Age-associated decline of immune system, termed immunosenescence, is characterized by low-grade systemic inflammation, known as inflammaging, together with T-cell functional dysregulation. Although affecting all individuals, different environmental as well genetic factors impinge on the individual's susceptibility or resilience to immunosenescence. Physical activity has been shown to improve autonomy and functionality in older adults. However, if physical activity affects immunosenescence or inflammaging remains unknown. The purpose of this study was to analyze immunosenescence and inflammaging in elderly individuals by measuring peripheral naïve T cells and interleukin (IL) -6 from peripheral blood and evaluate the impact of physical activity on T cell dysregulation and inflammaging. Thirty (30) elderly volunteers (10 males and 20 females), and 7 young controls (2 males ad 7 females), were recruited for this study. A methodology questionnaire was used to evaluate different parameters such as physical activity, and peripheral naïve CD4+ and CD8+ T cells and serum IL-6 were measured by FACS and ELISA respectively. Our results shown that naïve T cells decline, and IL-6 levels increase as older people age. Interestingly, we observed strong negative correlation between naïve T cells numbers and IL-6 levels in older adults, suggesting a direct link between reduced naïve T cell pool and increased inflammaging. Continuous physical activity during youth did not affect immunosenescence and inflammaging in elderly, but physical activity during elderly increase naïve T cell numbers and reduce inflammaging in older subjects. Our results showed reduced number of naïve T cells and increased levels of IL-6 as elder people get older. Moreover, the strong negative correlation between these parameters suggest that naïve T cells can have a direct suppressive activity over innate immune components. Furthermore, physical activity during elderly can reduce immunosenescence and inflammaging in older subjects. [ABSTRACT FROM AUTHOR]