Differential T-cell receptor signals for T helper cell programming

Prednisolone improves hippocampal regeneration after trimethyltin-induced neurodegeneration in association with prevention of T lymphocyte infiltration

The endogenous regenerative capacity of the brain is quite weak; however, a regenerative reaction, the production of new neurons (neurogenesis), has been reported to occur in brain lesions. In addition, leukocytes are well known to infiltrate brain lesions. Therefore, leukocytes would also have a link with regenerative neurogenesis; however, their role has not been fully elucidated. In this study, we investigated leukocyte infiltration and its influence on brain tissue regeneration in a trimethyltin (TMT)-injected mouse model of hippocampal regeneration. Immunohistochemically, CD3-positive T lymphocytes were found in the hippocampal lesion of TMT-injected mice. Prednisolone (PSL) treatment inhibited T lymphocyte infiltration and increased neuronal nuclei (NeuN)-positive mature neurons and doublecortin (DCX)-positive immature neurons in the hippocampus. Investigation of bromodeoxyuridine (BrdU)-labeled newborn cells revealed the percentage of BrdU/NeuN- and BrdU/DCX-positive cells increased by PSL treatment. These results indicate that infiltrated T lymphocytes prevent brain tissue regeneration by inhibiting hippocampal neurogenesis.

Phosphorylation of hnRNP A1-Serine 199 Is Not Required for T Cell Differentiation and Function

hnRNP A1 is an important RNA-binding protein that influences many stages of RNA processing, including transcription, alternative splicing, mRNA nuclear export, and RNA stability. However, the role of hnRNP A1 in immune cells, specifically CD4+ T cells, remains unclear. We previously showed that Akt phosphorylation of hnRNP A1 was dependent on TCR signal strength and was associated with Treg differentiation. To explore the impact of hnRNP A1 phosphorylation by Akt on CD4+ T cell differentiation, our laboratory generated a mutant mouse model, hnRNP A1-S199A (A1-MUT) in which the major Akt phosphorylation site on hnRNP A1 was mutated to alanine using CRISPR Cas9 technology. Immune profiling of A1-MUT mice revealed changes in the numbers of Tregs in the mesenteric lymph node. We found no significant differences in naive CD4+ T cell differentiation into Th1, Th2, Th17, or T regulatory cells (Tregs) in vitro. In vivo, Treg differentiation assays using OTII-A1-Mut CD4+ T cells exposed to OVA food revealed migration and homing defects in the A1-MUT but no change in Treg induction. A1-MUT mice were immunized with NP- keyhole limpet hemocyanin, and normal germinal center development, normal numbers of NP-specific B cells, and no change in Tfh numbers were observed. In conclusion, Akt phosphorylation of hnRNP A1 S199 does not play a role in CD4+ T cell fate or function in the models tested. This hnRNP A1-S199A mouse model should be a valuable tool to study the role of Akt phosphorylation of hnRNP A1-S199 in different cell types or other mouse models of human disease.

Does human homology reduce the potential immunogenicity of non-antibody scaffolds?

Biologics developers are moving beyond antibodies for delivery of a wide range of therapeutic interventions. These non-antibody modalities are often based on 'natural' protein scaffolds that are modified to deliver bioactive sequences. Both human-derived and non-human-sourced scaffold proteins have been developed. New types of "non-antibody" scaffolds are still being discovered, as they offer attractive alternatives to monoclonals due to their smaller size, improved stability, and ease of synthesis. They are believed to have low immunogenic potential. However, while several human-sourced protein scaffolds have not been immunogenic in clinical studies, this may not predict their overall performance in other therapeutic applications. A preliminary evaluation of their potential for immunogenicity is warranted. Immunogenicity risk potential has been clearly linked to the presence of T "helper" epitopes in the sequence of biologic therapeutics. In addition, tolerogenic epitopes are present in some human proteins and may decrease their immunogenic potential. While the detailed sequences of many non-antibody scaffold therapeutic candidates remain unpublished, their backbone sequences are available for review and analysis. We assessed 12 example non-antibody scaffold backbone sequences using our epitope-mapping tools (EpiMatrix) for this perspective. Based on EpiMatrix scoring, their HLA DRB1-restricted T cell epitope content appears to be lower than the average protein, and sequences that may act as tolerogenic epitopes are present in selected human-derived scaffolds. Assessing the potential immunogenicity of scaffold proteins regarding self and non-self T cell epitopes may be of use for drug developers and clinicians, as these exciting new non-antibody molecules begin to emerge from the preclinical pipeline into clinical use.

SLC10A3 Is a Prognostic Biomarker and Involved in Immune Infiltration and Programmed Cell Death in Lower Grade Glioma

BACKGROUND

The association between SLC10A3 (solute carrier family 10 member 3) and lower grade glioma (LGG) remains unclear.

METHODS

We used public databases and bioinformatics analysis to analyze SLC10A3. These included The Cancer Genome Atlas, Genotype-Tissue Expansion, Chinese Glioma Genome Atlas, Human Protein Atlas, GeneCards, cBioPortal, Search Tool for the Retrieval of Interacting Genes/Proteins, Gene Expression Profiling Interactive Analysis, Tumor Immune Estimation Resource, Tumor-Immune System Interaction Database, receiver operating characteristic curve analysis, Kaplan-Meier analysis, Cox analysis, nomograms, calibration plots, gene ontology/Kyoto Encyclopedia of Genes and Genomes enrichment analysis, gene set enrichment analysis, single-sample gene set enrichment analysis, and Spearman's correlation analysis.

RESULTS

SLC10A3 was upregulated in adrenocortical carcinoma, glioblastoma, and LGG and was associated with good overall survival (OS) in adrenocortical carcinoma and poor OS in LGG and glioblastoma. SLC10A3 was increased with increased World Health Organization grade, upregulated in isocitrate dehydrogenase-wild type, 1p/19q (chromosome arms 1p and 19q) non-co-deleted, and higher in astrocytoma. Patients with LGG were grouped by the occurrence of the clinical outcome endpoints (i.e., OS, disease-specific survival [DSS], and progression-free interval events). Genetic alterations in SLC10A3 were associated with poor progression-free survival in LGG. Most of clinical characteristics were associated with the SLC10A3 expression level. SLC10A3 with diagnostic and prognostic value (OS, DSS, and progression-free interval) was an independent prognostic factor in LGG. Moreover, Nomograms (WHO grade, 1p/19q codeletion, age and SLC10A3) had moderately accurate predictive for OS and DSS. Functional analysis showed that SLC10A3 might participate in the transport of multiple substances, neurogenic signaling, immune response, and programmed cell death in LGG. SLC10A3 correlated with immune infiltration in LGG and moderately correlated with the gene signature of pyroptosis, lysosome-dependent cell death, necroptosis, apoptosis, ferroptosis, alkaliptosis, and autophagy-dependent cell death.

CONCLUSIONS

SLC10A3 is a potential diagnostic and prognostic biomarker for LGG and might be associated with substance transport, neurogenic signaling, immune infiltration, and programmed cell death in LGG.

CD4 T-Cell Subsets and the Pathophysiology of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an umbrella term for the chronic immune-mediated idiopathic inflammation of the gastrointestinal tract, manifesting as Crohn's disease (CD) or ulcerative colitis (UC). IBD is characterized by exacerbated innate and adaptive immunity in the gut in association with microbiota dysbiosis and the disruption of the intestinal barrier, resulting in increased bacterial exposure. In response to signals from microorganisms and damaged tissue, innate immune cells produce inflammatory cytokines and factors that stimulate T and B cells of the adaptive immune system, and a prominent characteristic of IBD patients is the accumulation of inflammatory T-cells and their proinflammatory-associated cytokines in intestinal tissue. Upon antigen recognition and activation, CD4 T-cells differentiate towards a range of distinct phenotypes: T helper(h)1, Th2, Th9, Th17, Th22, T follicular helper (Tfh), and several types of T-regulatory cells (Treg). T-cells are generated according to and adapt to microenvironmental conditions and participate in a complex network of interactions among other immune cells that modulate the further progression of IBD. This review examines the role of the CD4 T-cells most relevant to IBD, highlighting how these cells adapt to the environment and interact with other cell populations to promote or inhibit the development of IBD.

Recent insights into the role of Akt in CD4 T-cell activation and differentiation: alternative splicing and beyond

The activation and differentiation of CD4⁺ T cells is a complex process that is controlled by many factors. A critical component of the signaling pathway triggered following T-cell receptor (TCR) engagement is the serine threonine kinase Akt. Akt is involved in the control of many cellular processes including proliferation, metabolism, and differentiation of specific T_H-cell subsets. Recent work has shown that, depending on the nature or strength of the TCR activation, Akt may activate different sets of substrates which then lead to differential cellular outcomes. Akt plays an important role in controlling the strength of the TCR signal and several recent studies have identified novel mechanisms including control of the expression of negative regulators of TCR signaling, and the influence on regulatory T cells (Treg) and T_H17 differentiation. Many of these functions are mediated via control of the FoxO family of transcription factors, that play an important role in metabolism and Th cell differentiation. A theme that is emerging is that Akt does not function in the same way in all T-cell types. We highlight differences between CD4 and CD8 T cells as well as between Treg, T_H17, and T_FH cells. While Akt activity has been implicated in the control of alternative splicing in tumor cells, recent studies are emerging that indicate that similar functions may exist in CD4 T cells. In this mini review, we highlight some of the recent advances in these areas of Akt function that demonstrate the varied role that Akt plays in the function of CD4 T cells.

The impact of blood Transfusion on T Helper Cells and Cytokines in Transfusion-Refractory Patients: a Prospective Study

Red blood cell (RBC) transfusion can increase patients' hemoglobin levels and improve hypoxia. The factors affecting the transfusion efficacy include immune and nonimmune factors. The objective of this study was to explore the impact of blood transfusion on T helper (Th) cell ratios and levels of serum cytokines in RBC transfusion-refractory patients. In this prospective study, anemic patients receiving RBC transfusion were enrolled. Peripheral venous blood samples were extracted from patients before RBC transfusion and within 24 h after transfusion. Th cell ratios and levels of serum cytokines were detected by flow cytometry. Differences in Th cell ratios and levels of serum cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ) between pretransfusion and posttransfusion were compared. A total of 47 patients agreed to participate in this study. They were grouped according to incremental Hb levels, 20 (42.55%) patients were divided into the RBC transfusion refractory group, while 27 (57.45%) patients were in the validity group. The expected Hb increment was defined by a panel of Chinese experts. In RBC transfusion-refractory patients, Th1 and Th2 cell ratios increased while levels of serum IL-2 and IL-10 decreased after transfusion. In RBC transfusion validity patients, there were no significant changes in Th cell ratios or levels of serum cytokines between pretransfusion and posttransfusion. We found that Th1 and Th2 cell ratios increased while serum IL-2 and IL-10 levels decreased after transfusion in RBC-refractory patients.

The Pathogenicity and Synergistic Action of Th1 and Th17 Cells in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs), including ulcerative colitis and Crohn's disease, are characterized by chronic idiopathic inflammation of gastrointestinal tract. Although the pathogenesis of IBD remains unknown, intestinal immune dysfunction has been considered as the core pathogenesis. In the intestinal immune system, T helper 1 (Th1) and Th17 cells are indispensable for intestine homeostasis via preventing pathogenic bacteria invasion, regulating metabolism and functions of intestinal epithelial cells (IECs), and promoting IEC self-renewal. However, during the development of IBD, Th1 and Th17 cells acquire the pathogenicity and change from the maintainer of intestinal homeostasis to the destroyer of intestinal mucosa. Because of coexpressing interferon-γ and interleukin-17A, Th17 cells with pathogenicity are named as pathogenic Th17 cells. In disease states, Th1 cells impair IEC programs by inducing IEC apoptosis, recruiting immune cells, promoting adhesion molecules expression of IECs, and differentiating to epithelial cell adhesion molecule-specific interferon γ-positive Th1 cells. Pathogenic Th17 cells induce IEC injury by triggering IBD susceptibility genes expression of IECs and specifically killing IECs. In addition, Th1 and pathogenic Th17 cells could cooperate to induce colitis. The evidences from IBD patients and animal models demonstrate that synergistic action of Th1 and pathogenic Th17 cells occurs in the diseases development and aggravates the mucosal inflammation. In this review, we focused on Th1 and Th17 cell programs in homeostasis and intestine inflammation and specifically discussed the impact of Th1 and Th17 cell pathogenicity and their synergistic action on the onset and the development of IBD. We hoped to provide some clues for treating IBD.

Molecular Mechanisms of Anti-Neoplastic and Immune Stimulatory Properties of Oncolytic Newcastle Disease Virus

Oncolytic viruses represent interesting anti-cancer agents with high tumor selectivity and immune stimulatory potential. The present review provides an update of the molecular mechanisms of the anti-neoplastic and immune stimulatory properties of the avian paramyxovirus, Newcastle Disease Virus (NDV). The anti-neoplastic activities of NDV include (i) the endocytic targeting of the GTPase Rac1 in Ras-transformed human tumorigenic cells; (ii) the switch from cellular protein to viral protein synthesis and the induction of autophagy mediated by viral nucleoprotein NP; (iii) the virus replication mediated by viral RNA polymerase (large protein (L), associated with phosphoprotein (P)); (iv) the facilitation of NDV spread in tumors via the membrane budding of the virus progeny with the help of matrix protein (M) and fusion protein (F); and (v) the oncolysis via apoptosis, necroptosis, pyroptosis, or ferroptosis associated with immunogenic cell death. A special property of this oncolytic virus consists of its potential for breaking therapy resistance in human cancer cells. Eight examples of this important property are presented and explained. In healthy human cells, NDV infection activates the RIG-MAVs immune signaling pathway and establishes an anti-viral state based on a strong and uninhibited interferon α,ß response. The review also describes the molecular determinants and mechanisms of the NDV-mediated immune stimulatory effects, in which the viral hemagglutinin-neuraminidase (HN) protein plays a prominent role. The six viral proteins provide oncolytic NDV with a special profile in the treatment of cancer.

IL13 May Play an Important Role in Developing Eosinophilic Chronic Rhinosinusitis and Eosinophilic Otitis Media with Severe Asthma

A woman in her 50s was a super responder to benralizumab administered for the treatment of severe bronchial asthma (BA) with eosinophilic chronic rhinosinusitis with nasal polyp (ECRS) and eosinophilic otitis media (EOM). She exhibited the gradual exacerbation of ECRS/EOM despite good control of BA approximately 1 year after benralizumab initiation. Therefore, the treatment was switched to dupilumab, and the condition of the paranasal sinuses and middle ear greatly improved with the best control of her asthma. The patient reported that her physical condition was the best of her life. However, she developed a pulmonary opacity on chest computed tomography after 6 months. Histological examination of the lung parenchyma and cell differentiation of the bronchoalveolar lavage fluid indicated atypical chronic eosinophilic pneumonia, and treatment was switched to mepolizumab. Similarly to the period of benralizumab treatment, exacerbation of ECRS/EOM reduced her quality of life approximately 10 months after the administration of mepolizumab. Dupilumab was again introduced as a replacement for mepolizumab. The clinical course and consideration of the interaction between inflammatory cells led us to speculate that interleukin-13 could play a key role in the development of ECRS/EOM with severe BA.

USP12 promotes CD4+ T cell responses through deubiquitinating and stabilizing BCL10

Deubiquitinases (DUBs) regulate diverse biological processes and represent a novel class of drug targets. However, the biological function of only a small fraction of DUBs, especially in adaptive immune response regulation, is well-defined. In this study, we identified DUB ubiquitin-specific peptidase 12 (USP12) as a critical regulator of CD4⁺ T cell activation. USP12 plays an intrinsic role in promoting the CD4⁺ T cell phenotype, including differentiation, activation, and proliferation. Although USP12-deficient CD4⁺ T cells protected mice from autoimmune diseases, the immune response against bacterial infection was subdued. USP12 stabilized B cell lymphoma/leukemia 10 (BCL10) by deubiquitinating, and thereby activated the NF-κB signaling pathway. Interestingly, this USP12 regulatory mechanism was identified in CD4⁺ T cells, but not in CD8⁺ T cells. Our study results showed that USP12 activated CD4⁺ T cell signaling, and targeting USP12 might help develop therapeutic interventions for treating inflammatory diseases or pathogen infections.

Breast adipose regulation of premenopausal breast epithelial phenotype involves interleukin 10

Epidemiological studies inversely associate BMI with breast cancer risk in premenopausal women, but the pathophysiological linkage remains ill-defined. Despite the documented relevance of the 'local' environment to breast cancer progression and the well-accepted differences in transcriptome and metabolic properties of anatomically distinct fat depots, specific breast adipose contributions to the proliferative potential of non-diseased breast glandular compartment are not fully understood. To address early breast cancer causation in the context of obesity status, we compared the cellular and molecular phenotypes of breast adipose and matched breast glandular tissue from premenopausal non-obese (mean BMI = 27 kg/m2) and obese (mean BMI = 44 kg/m2) women. Breast adipose from obese women showed higher expression levels of adipogenic, pro-inflammatory, and estrogen synthetic genes than from non-obese women. Obese breast glandular tissue displayed lower proliferation and inflammatory status and higher expression of anti-proliferative/pro-senescence biomarkers TP53 and p21 than from non-obese women. Transcript levels for T-cell receptor and co-receptors CD3 and CD4 were higher in breast adipose of obese cohorts, coincident with elevated adipose interleukin 10 (IL10) and FOXP3 gene expression. In human breast epithelial cell lines MCF10A and HMEC, recombinant human IL10 reduced cell viability and CCND1 transcript levels, increased those of TP53 and p21, and promoted (MCF10A) apoptosis. Our findings suggest that breast adipose-associated IL10 may mediate paracrine interactions between non-diseased breast adipose and breast glandular compartments and highlight how breast adipose may program the local inflammatory milieu, partly by recruiting FOXP3+ T regulatory cells, to influence premenopausal breast cancer risk.

TRAF3 in T Cells Restrains Negative Regulators of LAT to Promote TCR/CD28 Signaling

The adaptor protein TNFR-associated factor 3 (TRAF3) is required for in vivo T cell effector functions and for normal TCR/CD28 signaling. TRAF3-mediated enhancement of TCR function requires engagement of both CD3 and CD28, but the molecular mechanisms underlying how TRAF3 interacts with and impacts TCR/CD28-mediated complexes to enhance their signaling remains an important knowledge gap. We investigated how TRAF3 is recruited to, and regulates, CD28 as a TCR costimulator. Direct association with known signaling motifs in CD28 was dispensable for TRAF3 recruitment; rather, TRAF3 associated with the CD28-interacting protein linker of activated T cells (LAT) in human and mouse T cells. TRAF3-LAT association required the TRAF3 TRAF-C domain and a newly identified TRAF2/3 binding motif in LAT. TRAF3 inhibited function of the LAT-associated negative regulatory protein Dok1, which is phosphorylated at an inhibitory tyrosine residue by the tyrosine kinase breast tumor kinase (Brk/PTK6). TRAF3 regulated Brk activation in T cells, limiting the association of protein tyrosine phosphatase 1B (PTP1B) with the LAT complex. In TRAF3-deficient cells, LAT complex-associated PTP1B was associated with dephosphorylation of Brk at an activating tyrosine residue, potentially reducing its ability to inhibit Dok1. Consistent with these findings, inhibiting PTP1B activity in TRAF3-deficient T cells rescued basal and TCR/CD28-mediated activation of Src family kinases. These results reveal a new mechanism for promotion of TCR/CD28-mediated signaling through restraint of negative regulation of LAT by TRAF3, enhancing the understanding of regulation of the TCR complex.

Helper T Cells in Idiopathic Membranous Nephropathy

Idiopathic membranous nephropathy (IMN) is an autoimmune disease in which the immune system produces an antibody response to its own antigens due to impaired immune tolerance. Although antibodies are derived from plasma cells differentiated by B cells, the T-B cells also contribute a lot to the immune system. In particular, the subsets of helper T (Th) cells, including the dominant subsets such as Th2, Th17, and follicular helper T (Tfh) cells and the inferior subsets such as regulatory T (Treg) cells, shape the immune imbalance of IMN and promote the incidence and development of autoimmune responses. After reviewing the physiological knowledge of various subpopulations of Th cells and combining the existing studies on Th cells in IMN, the role model of Th cells in IMN was explained in this review. Finally, the existing clinical treatment regimens for IMN were reviewed, and the importance of the therapy for Th cells was highlighted.

Ceramide Synthase 2 Null Mice Are Protected from Ovalbumin-Induced Asthma with Higher T Cell Receptor Signal Strength in CD4+ T Cells

(1) Background: six mammalian ceramide synthases (CerS1–6) determine the acyl chain length of sphingolipids (SLs). Although ceramide levels are increased in murine allergic asthma models and in asthmatic patients, the precise role of SLs with specific chain lengths is still unclear. The role of CerS2, which mainly synthesizes C22–C24 ceramides, was investigated in immune responses elicited by airway inflammation using CerS2 null mice. (2) Methods: asthma was induced in wild type (WT) and CerS2 null mice with ovalbumin (OVA), and inflammatory cytokines and CD4 (cluster of differentiation 4)+ T helper (Th) cell profiles were analyzed. We also compared the functional capacity of CD4+ T cells isolated from WT and CerS2 null mice. (3) Results: CerS2 null mice exhibited milder symptoms and lower Th2 responses than WT mice after OVA exposure. CerS2 null CD4+ T cells showed impaired Th2 and increased Th17 responses with concomitant higher T cell receptor (TCR) signal strength after TCR stimulation. Notably, increased Th17 responses of CerS2 null CD4+ T cells appeared only in TCR-mediated, but not in TCR-independent, treatment. (4) Conclusions: altered Th2/Th17 immune response with higher TCR signal strength was observed in CerS2 null CD4+ T cells upon TCR stimulation. CerS2 and very-long chain SLs may be therapeutic targets for Th2-related diseases such as asthma.

Eosinophilia/Hypereosinophilia in the Setting of Reactive and Idiopathic Causes, Well-Defined Myeloid or Lymphoid Leukemias, or Germline Disorders

OBJECTIVES

To report the findings of the 2019 Society for Hematopathology/European Association for Haematopathology Workshop within the categories of reactive eosinophilia, hypereosinophilic syndrome (HES), germline disorders with eosinophilia (GDE), and myeloid and lymphoid neoplasms associated with eosinophilia (excluding entities covered by other studies in this series).

METHODS

The workshop panel reviewed 109 cases, assigned consensus diagnosis, and created diagnosis-specific sessions.

RESULTS

The most frequent diagnosis was reactive eosinophilia (35), followed by acute leukemia (24). Myeloproliferative neoplasms (MPNs) received 17 submissions, including chronic eosinophilic leukemia, not otherwise specified (CEL, NOS). Myelodysplastic syndrome (MDS), MDS/MPN, and therapy-related myeloid neoplasms received 11, while GDE and HES received 12 and 11 submissions, respectively.

CONCLUSIONS

Hypereosinophilia and HES are defined by specific clinical and laboratory criteria. Eosinophilia is commonly reactive. An acute leukemic onset with eosinophilia may suggest core-binding factor acute myeloid leukemia, blast phase of chronic myeloid leukemia, BCR-ABL1-positive leukemia, or t(5;14) B-lymphoblastic leukemia. Eosinophilia is rare in MDS but common in MDS/MPN. CEL, NOS is a clinically aggressive MPN with eosinophilia as the dominant feature. Bone marrow morphology and cytogenetic and/or molecular clonality may distinguish CEL from HES. Molecular testing helps to better subclassify myeloid neoplasms with eosinophilia and to identify patients for targeted treatments.

AIMP1 regulates TCR signaling and induces differentiation of regulatory T cells by interfering with lipid raft association

In addition to a role in translation, AIMP1 is secreted to affect various immune cells, such as macrophages, dendritic cells, B cells, and natural killer cells. However, the direct effects of AIMP1 on T cells have not yet been reported. In this study, we investigated whether AIMP1 could modulate T cell responses directly. Results revealed that AIMP1 significantly inhibited T cell receptor (TCR)-dependent activation and proliferation of CD4 T cells, as well as decreased TCR stimuli-induced Ca²⁺ influx in CD4 T cells. In addition, microscopic analysis revealed that lipid raft association in response to TCR engagement was significantly reduced in the presence of AIMP1, and the phosphorylation of PLCγ and PI3K was also down-regulated in CD4 T cells by AIMP1. Furthermore, AIMP1 specifically enhanced the differentiation of regulatory T (Treg) cells, while it had no effect on T helper type 1 (Th1), type 2 (Th2), and type 17 (Th17) cell differentiation. Collectively, these results indicate that AIMP1 affects T cells directly by down-regulating TCR signaling complex formation and inducing Treg cell differentiation in CD4 T cells.

Imprinting and Editing of the Human CD4 T Cell Response to Influenza Virus

Immunity to influenza is unique among pathogens, in that immune memory is established both via intermittent lung localized infections with highly variable influenza virus strains and by intramuscular vaccinations with inactivated protein-based vaccines. Studies in the past decades have suggested that the B cell responses to influenza infection and vaccination are highly biased by an individual's early history of influenza infection. This reactivity likely reflects both the competitive advantage that memory B cells have in an immune response and the relatively limited diversity of epitopes in influenza hemagglutinin that are recognized by B cells. In contrast, CD4 T cells recognize a wide array of epitopes, with specificities that are heavily influenced by the diversity of influenza antigens available, and a multiplicity of functions that are determined by both priming events and subsequent confrontations with antigens. Here, we consider the events that prime and remodel the influenza-specific CD4 T cell response in humans that have highly diverse immune histories and how the CD4 repertoire may be edited in terms of functional potential and viral epitope specificity. We discuss the consequences that imprinting and remodeling may have on the potential of different human hosts to rapidly respond with protective cellular immunity to infection. Finally, these issues are discussed in the context of future avenues of investigation and vaccine strategies.

The impact of inflationary cytomegalovirus-specific memory T cells on anti-tumour immune responses in patients with cancer

Human cytomegalovirus (CMV) is a ubiquitous, persistent beta herpesvirus. CMV infection contributes to the accumulation of functional antigen-specific CD8⁺ T-cell pools with an effector-memory phenotype and enrichment of these immune cells in peripheral organs. We review here this 'memory T-cell inflation' phenomenon and associated factors including age and sex. 'Collateral damage' due to CMV-directed immune reactivity may occur in later stages of life - arising from CMV-specific immune responses that were beneficial in earlier life. CMV may be considered an age-dependent immunomodulator and a double-edged sword in editing anti-tumour immune responses. Emerging evidence suggests that CMV is highly prevalent in patients with a variety of cancers, particularly glioblastoma. A better understanding of CMV-associated immune responses and its implications for immune senescence, especially in patients with cancer, may aid in the design of more clinically relevant and tailored, personalized treatment regimens. 'Memory T-cell inflation' could be applied in vaccine development strategies to enrich for immune reactivity where long-term immunological memory is needed, e.g. in long-term immune memory formation directed against transformed cells.