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Alternative polyadenylation in the 3' UTR (3' UTR-APA) is a mode of gene expression regulation, fundamental for mRNA stability, translation and localization. In the immune system, it was shown that upon T cell activation, there is an increase in the relative expression of mRNA isoforms with short 3' UTRs resulting from 3' UTR-APA. However, the functional significance of 3' UTR-APA remains largely unknown. Here, we studied the physiological function of 3' UTR-APA in the regulation of Myeloid Cell Leukemia 1 (MCL1), an anti-apoptotic member of the Bcl-2 family essential for T cell survival. We found that T cells produce two MCL1 mRNA isoforms (pA1 and pA2) by 3' UTR-APA. We show that upon T cell activation, there is an increase in both the shorter pA1 mRNA isoform and MCL1 protein levels. Moreover, the less efficiently translated pA2 isoform is downregulated by miR-17, which is also more expressed upon T cell activation. Therefore, by increasing the expression of the more efficiently translated pA1 mRNA isoform, which escapes regulation by miR-17, 3' UTR-APA fine tunes MCL1 protein levels, critical for activated T cells' survival. Furthermore, using CRISPR/Cas9-edited cells, we show that depletion of either pA1 or pA2 mRNA isoforms causes severe defects in mitochondria morphology, increases apoptosis and impacts cell proliferation. Collectively, our results show that MCL1 alternative polyadenylation has a key role in the regulation of MCL1 protein levels upon T cell activation and reveal an essential function for MCL1 3' UTR-APA in cell viability and mitochondria dynamics., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The selenoprotein family includes 25 members, many of which are antioxidant or redox regulating enzymes. A unique member of this family is Selenoprotein I (SELENOI), which does not catalyze redox reactions, but instead is an ethanolamine phosphotransferase (Ept). In fact, the characteristic selenocysteine residue that defines selenoproteins lies far outside of the catalytic domain of SELENOI. Furthermore, data using recombinant SELENOI lacking the selenocysteine residue have suggested that the selenocysteine amino acid is not directly involved in the Ept reaction. SELENOI is involved in two different pathways for the synthesis of phosphatidylethanolamine (PE) and plasmenyl PE, which are constituents of cellular membranes. Ethanolamine phospholipid synthesis has emerged as an important process for metabolic reprogramming that occurs in pluripotent stem cells and proliferating tumor cells, and this review discusses roles for upregulation of SELENOI during T cell activation, proliferation, and differentiation. SELENOI deficiency lowers but does not completely diminish de novo synthesis of PE and plasmenyl PE during T cell activation. Interestingly, metabolic reprogramming in activated SELENOI deficient T cells is impaired and this reduces proliferative capacity while favoring tolerogenic to pathogenic phenotypes that arise from differentiation. The implications of these findings are discussed related to vaccine responses, autoimmunity, and cell-based therapeutic approaches.

COVID-19 is characterized by a dysregulation of inflammatory cytokines ultimately resulting a cytokine storm that can result in significant morbidity and mortality. We developed an in-vitro assay using activated peripheral blood mononuclear cells (PBMCs) stimulated with lipopolysaccharide (LPS) or CD3 + CD28 to examine secretion of cytokines from antigen presenting cells (APCs) and T cells, respectively, in donor patients with a history of COVID-19 (convalescent) and uninfected negative controls. We hypothesized that a novel antioxidant called Tempol may decrease cytokines from activated peripheral blood cells from both COVID-19 patients and normal donors. Preincubation of immune cells with Tempol resulted in a significant (P < 0.05) decrease in multiple T cell and APC-derived cytokines from both cells of COVID-19 (n = 7) and uninfected donors (n = 7). These preliminary results suggest that Tempol has strong in-vitro anti-cytokine activity and supports additional studies examining the use of Tempol for the treatment of COVID-19., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

The function of a T cell depends on its subtype and activation state. Here, we show that imaging of the autofluorescence lifetime signals of quiescent and activated T cells can be used to classify the cells. T cells isolated from human peripheral blood and activated in culture using tetrameric antibodies against the surface ligands CD2, CD3 and CD28 showed specific activation-state-dependent patterns of autofluorescence lifetime. Logistic regression models and random forest models classified T cells according to activation state with 97-99% accuracy, and according to activation state (quiescent or activated) and subtype (CD3 + CD8 + or CD3 + CD4 + ) with 97% accuracy. Autofluorescence lifetime imaging can be used to non-destructively determine T-cell function.

The incidence of papillary thyroid cancer (PTC) with concomitant Hashimoto thyroiditis (HT) is increasing. Interleukin (IL)-10 is a cytokine previously reported to be elevated in this condition. Evidence from multiple human malignancies showed IL-10 participated in tumor immunity and exhibited therapeutic potential. The aim of this study is to investigate whether IL-10 interferes with tumor immunity in PTC with concomitant HT. Expression of IL-10 and major histocompatibility complex (MHC) class Ⅰ were compared with PTC tissues with or without concomitant HT. PTC cell lines K1 and TPC-1 were stimulated with IL-10 and analyzed for MHC class Ⅰ expression afterward. T-cell activation, production of IL-2 and interferon (IFN)-γ and programmed death-1 (PD-1) expression were assessed by coculture of donor peripheral blood lymphocytes (PBLs) with IL-10-pretreated PTC cells. Programmed death-ligand 1 (PD-L1) expression was measured in PTC tissues and IL-10-pretreated cells of K1 and TPC-1. Increased levels of IL-10 and MHC class Ⅰ were observed in PTC with concomitant HT. IL-10 stimulation increased MHC class Ⅰ expression of PTC cells in vitro. Coculture of PBLs with IL-10-pretreated PTC cells enhanced T-cell activation (% cluster of differentiation [CD]25+ of CD3+T cells) and increased IL-2 production along with decreased IFN-γ secretion and PD-1 expression. Reduced PD-L1 expression was seen in PTC + HT tissue samples and IL-10-stimulated PTC cell lines. Elevated IL-10 expression in PTC with concomitant HT restores MHC class Ⅰ expression and interferes with tumor immunity. The potential mechanism of IL-10 in tumor immunity needs further investigation., (© Endocrine Society 2020.)

T cell activation by dendritic cells (DCs) involves forces exerted by the T cell actin cytoskeleton, which are opposed by the cortical cytoskeleton of the interacting antigen-presenting cell. During an immune response, DCs undergo a maturation process that optimizes their ability to efficiently prime naïve T cells. Using atomic force microscopy, we find that during maturation, DC cortical stiffness increases via a process that involves actin polymerization. Using stimulatory hydrogels and DCs expressing mutant cytoskeletal proteins, we find that increasing stiffness lowers the agonist dose needed for T cell activation. CD4 + T cells exhibit much more profound stiffness dependency than CD8 + T cells. Finally, stiffness responses are most robust when T cells are stimulated with pMHC rather than anti-CD3ε, consistent with a mechanosensing mechanism involving receptor deformation. Taken together, our data reveal that maturation-associated cytoskeletal changes alter the biophysical properties of DCs, providing mechanical cues that costimulate T cell activation., Competing Interests: DB, VC, LA, JB No competing interests declared, (© 2020, Blumenthal et al.)

The promising outcomes of immune-checkpoint based immunotherapies in cancer have provided a proportional perspective ahead of exploiting similar approaches in allotransplantation. Belatacept (CTLA-4-Ig) is an example of costimulation blockers successfully exploited in renal transplantation. Due to the wide range of regulatory molecules characterized in the past decades, some of these molecules might be candidates as immunomodulators in the case of tolerance induction in transplantation. Although there are numerous attempts on the apprehension of the effects of co-signaling molecules on immune response, the necessity for a better understanding is evident. By increasing the knowledge on the biology of co-signaling pathways, some pitfalls are recognized and improved approaches are proposed. The blockage of CD80/CD28 axis is an instance of evolution toward more efficacy. It is now evident that anti-CD28 antibodies are more effective than CD80 blockers in animal models of transplantation. Other co-signaling axes such as PD-1/PD-L1, CD40/CD154, 2B4/CD48, and others discussed in the present review are examples of critical immunomodulatory molecules in allogeneic transplantation. We review here the outcomes of recent experiences with co-signaling molecules in preclinical studies of solid organ transplantation., (© 2019 Wiley Periodicals, Inc.)

Tumour-associated macrophages (TAMs) inhibit the killing effect of T lymphocytes on tumour cells through the immunocheckpoint programmed death ligand-1 (PD-L1)/programmed death-1 (PD-1) axis. TAMs-targeted therapy is a promising approach that could be used to reverse the immunosuppressive tumour microenvironment. Here, we further report CMPB90-1, a novel natural polysaccharide from Cordyceps militaris, could function as an anti-tumour modulator that resets TAMs from a tumour-promoting M2 phenotype to a tumour-killing M1 phenotype. This process involves reversing the functional inhibition of T lymphocytes by inhibiting the PD-L1/PD-1 axis between TAMs and T lymphocytes. Mechanistically, the membrane receptor of CMPB90-1 binding to M2 macrophages was identified by tandem mass spectrometry. CMPB90-1 converts immunosuppressive TAMs via binding to toll-like receptor 2 (TLR2), which causes the release of Ca 2+ and the activation of p38, Akt and NF-κB, or ERK. This process then leads to the polarization of TAMs from M2 phenotype to the M1 phenotype. In vivo experiment shows that CMPB90-1 is able to polarize TAMs into the M1 phenotype and has anti-tumour effects with improved safety. Additionally, the anti-tumour effects of CMPB90-1 in vivo depend on the phenotypic conversion of TAMs. The results demonstrated that CMPB90-1 could be developed as a potential immune-oncology treatment reagent., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Recent evidences suggested that Mesenchymal stem cells (MSCs) may be involved in tumor formation by modulating of the tumor microenvironment, but it is still unclear the potential of MSCs in the malignant transformation of oral mucosa. Using a chemically-induced oral carcinogenesis model by 4-nitroquinoline-1-oxide (4NQO), we generated precancerous lesions and cancerous lesions in the oral cavity of rats. Flow cytometric analysis on lesions derived single cell suspension revealed an increase in the proportion of MSCs and a decreased proportion of T cell during oral mucosa malignancy. Moreover, MSCs showed increased immunosuppression capacity on T cell proliferation during mucosa malignancy. At last, we demonstrated that higher frequency of lesions resident MSCs was correlated with more Ki67 expression in the lesion, which indicated higher cellular proliferative status in the lesions. Our study demonstrated that MSCs may play an important role in oral mucosa malignant transformation through regulating T cell proliferation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

T-lymphocytes are the principle coordinators of the immune defense system and play a major role in the protection of our body against infections, intruders of non-self, and malignancies. To mount an immune response, T-cells need to be effectively employed to tissue sites of infection or inflammation and establish contacts with antigen-presenting cells (APCs) or malignant cells. Understanding how T-cells navigate toward their recruitment sites would offer new therapeutic opportunities. Advancement in the hardware and software upgrades of microscopy technology has created several efficient and easy-to-operate live cell imaging platforms. In this protocol, we present a generalized and simple-to-follow protocol for live cell imaging of migrating T-cells, which can also be adopted to visualize real-time tracking of intracellular signaling events.

The ability of activated T-lymphocytes to transmigrate toward certain chemokine is one of their characteristic functional properties. Here, we provide step-wise details about an in vitro technique to quantify the kinetics of chemotactic behavior of LFA-1-stimulated T-lymphocytes. The method described herein utilizes a noninvasive electrical impedance-based detection system to monitor T-cell chemotaxis in real-time.

Background: The immune response during P. falciparum infection is a two-edged sword, involving dysregulation of the inflammatory responses with several types of immune cells participating. Here we examined T-cell, monocyte/macrophage and neutrophil activation during P. falciparum infection by using soluble activation markers for these leukocyte subsets., Methods: In a prospective cross-sectional study clinical data and blood samples were collected from adults in Mozambique with P. falciparum infection, with (n = 70) and without (n = 61) co-infection with HIV-1, as well as HIV-infected patients with similar symptoms but without malaria (n = 58) and healthy controls (n = 52). Soluble (s)CD25, sCD14, sCD163 and myeloperoxidase (MPO) as markers for T-cell, monocyte/macrophage and neutrophil activation, respectively as well as CX3CL1, granzyme B and TIM-3 as markers of T-cell subsets and T-cell exhaustion, were analyzed., Results: All patient groups had raised levels of activation markers compared with healthy controls. Levels of sCD25 and MPO increased gradually from patient with HIV only to patient with malaria only, with the highest levels in the HIV/malaria group. In the malaria group as a whole, MPO, sCD14 and in particular sCD25 were correlated with disease severity. sCD163, sCD25 and in particular MPO correlated with the degree of parasitemia as assessed by qPCR. Patients with falciparum malaria also had signs of T-cell subset activation (i.e. increased granzyme B and CX3CL1) and T-cell exhaustion as assessed by high levels of TIM-3 particularly in patients co-infected with HIV., Conclusion: Our data support a marked immune activation in falciparum malaria involving all major leukocyte subsets with particular enhanced activation of neutrophils and T-cells in patients co-infected with HIV. Our findings also support a link between immune activation and immune exhaustion during falciparum malaria, particularly in relation to T-cell responses in patients co-infected with HIV.

Background/aim: Novel information on the role of endogenous compounds in regulating physiological and pathological process are of interest, as it may lead to the development of better strategies for disease management. The role of angiotensin II and the signaling of type 1 angiotensin II receptor (AGT1R) in T-lymphocyte activation and interleukin-2 (IL-2) production are largely unknown., Materials and Methods: Jurkat T-cells were treated with AGT1R inhibitor candesartan and stimulated with phorbol myristate acetate (PMA) and ionomycin. T-Cell activation, associated cytokine production and levels of signaling proteins were evaluated by flow cytometry and western blot analysis., Results: Candesartan significantly suppressed PMA and ionomycin-induced CD25 expression and IL-2 production. Regarding the molecular mechanism involved, we showed that such suppressive effects of blocking of AGT1R by candesartan resulted in the significant inhibition of ERK activation in PMA-stimulated Jurkat T-cells. The effect of ERK inhibition on T-cell activation was further confirmed. Treatment with FR180204, a specific ERK inhibitor, reduced T-cell activation and IL-2 secretion., Conclusion: AGT1R signaling is essential for T-cell activation and IL-2 production, and the inhibition of this pathway suppressed T-cell activation via an ERK-dependent mechanism., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Introduction: The burden of non-communicable diseases such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVDs) has drastically increased in developing countries over the years. Although recent evidence points to chronic immune activation to be a significant aspect in the pathogenesis and development of T2DM and CVDs, the exact role of T cells is not fully understood. Therefore, we aim to investigate T cell function and cardio vascular risk in T2DM. In addition, the therapeutic effect of blood glucose-lowering drugs to reverse hyperglycaemia induced T cell dysfunction and myocardial infarction will be reviewed., Methods: This will be a systematic review and meta-analysis of published studies assessing T cell activation and cardiovascular risk in adults with T2DM. The search strategy will include medical subject headings (MeSH) words for PubMed/MEDLINE database. The search terms will also be adapted to grey literature, Embase and Cochrane Central Register of Controlled Trials electronic databases. Studies will be independently screened by two reviewers using predefined criteria. Relevant eligible full texts will be screened and data will be extracted. Data extraction will be performed using a pre-piloted structured form. To assess the quality and strengths of evidence across selected studies, the Grading of Recommendations Assessment Development and Evaluation approach will be used. The Cochran's Q statistic and the I 2 statistics will be used to analyse statistical heterogeneity between studies. If included studies show substantial level of statistical heterogeneity, a random-effects meta-analysis will be performed using R statistical software., Discussions: This review will not require ethical approval, and the findings will be disseminated through peer-reviewed publication and conferences. Although other previous studies have reported deregulated T cell function in hyperglycaemia, the underlying mechanisms remain controversial. However, evidence suggests that T cells may be a key component in the development of T2DM and CVDs as its complication. Furthermore, they are a potential diagnostic and therapeutic target in the management of the disease., Systematic Review Registration: PROSPERO CRD42018099745.

Introduction: Due to the ability of pathogen-associated molecular patters and tumor necrosis factor receptor (TNFR) family costimulatory agonists to boost T cell responses, studies have combined Toll-like receptor (TLR) ligands with TNFR family costimulatory receptor agonists to induce impressive and long-lasting T cell responses. Although some studies have determined how these combinatorial vaccines promote enhanced T cell responses, much remains unknown about the mechanism used by these combinations to promote synergistic T cell responses - especially in settings of infectious diseases or cancer., Areas Covered: In this review, we look in detail at the signaling pathways induced by combinatorial targeting of TLR and TNFR family costimulatory members that help them promote synergistic T cell responses. Understanding this can greatly aid the development of novel vaccine regimens that promote cellular immune responses, which is essential for treating certain infectious diseases and cancer., Expert Opinion: Vaccines against some infectious diseases as well as therapeutic cancer vaccines require cellular immunity. Therefore, we evaluate here how signaling pathways induced by TLR ligand and costimulatory agonist combinations promote enhanced T cell responses during immunization with model antigens, viral pathogens, or tumor antigens. Once pathways that drive these combinatorial vaccines to boost T cell activation are identified, they can be incorporated in vaccines designed to target pathogens or cancer.

TCR-signaling strength generally correlates with peptide-MHC binding affinity; however, exceptions exist. We find high-affinity, yet non-stimulatory, interactions occur with high frequency in the human T cell repertoire. Here, we studied human TCRs that are refractory to activation by pMHC ligands despite robust binding. Analysis of 3D affinity, 2D dwell time, and crystal structures of stimulatory versus non-stimulatory TCR-pMHC interactions failed to account for their different signaling outcomes. Using yeast pMHC display, we identified peptide agonists of a formerly non-responsive TCR. Single-molecule force measurements demonstrated the emergence of catch bonds in the activating TCR-pMHC interactions, correlating with exclusion of CD45 from the TCR-APC contact site. Molecular dynamics simulations of TCR-pMHC disengagement distinguished agonist from non-agonist ligands based on the acquisition of catch bonds within the TCR-pMHC interface. The isolation of catch bonds as a parameter mediating the coupling of TCR binding and signaling has important implications for TCR and antigen engineering for immunotherapy., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Both respiratory syncytial virus (RSV) and influenza A virus (IAV) may infect human peripheral blood mononuclear leukocytes (PBMC) during the immune response to viral challenge as the cells are recruited to the respiratory tract. The current studies demonstrated differences in PBMC responses to the two viruses very early after exposure, including reduced fos protein and CD69 expression and IL-2 production by RSV-exposed T lymphocytes. Exposure to RSV resulted in reduced lymphocyte proliferation despite evidence of a virus-specific T lymphocyte frequency equivalent to that for influenza virus. Reduced RSV-induced proliferation was not due to apoptosis, which was itself reduced relative to that of influenza virus-exposed T lymphocytes. The data indicate that differential immune responses to RSV and influenza virus are determined early after exposure of human PBMC and support the concept that the anamnestic immune response that might prevent clinically evident reinfection is attenuated very soon after exposure to RSV. Thus, candidate RSV vaccines should be expected to reduce but not prevent clinical illness upon subsequent infection by RSV. Furthermore, effective therapeutic agents for RSV are likely to be needed, especially for high-risk populations, even after vaccine development., (© 2017 Wiley Periodicals, Inc.)

Nucleotide-binding oligomerization domain (Nod)-containing proteins Nod1 and Nod2 play important roles in the innate immune response to pathogenic microbes, but mounting data suggest these pattern recognition receptors might also play key roles in adaptive immune responses. Targeting Nod1 and Nod2 signaling pathways in T cells is likely to provide a new strategy to modify inflammation in a variety of disease states, particularly those that depend on Ag-induced T cell activation. To better understand how Nod1 and Nod2 proteins contribute to adaptive immunity, this study investigated their role in alloantigen-induced T cell activation and asked whether their absence might impact in vivo alloresponses using a severe acute graft versus host disease model. The study provided several important observations. We found that the simultaneous absence of Nod1 and Nod2 primed T cells for activation-induced cell death. T cells from Nod1 × 2 -/- mice rapidly underwent cell death upon exposure to alloantigen. The Nod1 × 2 -/- T cells had sustained p53 expression that was associated with downregulation of its negative regulator MDM2. In vivo, mice transplanted with an inoculum containing Nod1 × 2 -/- T cells were protected from severe graft versus host disease. The results show that the simultaneous absence of Nod1 and Nod2 is associated with accelerated T cell death upon alloantigen encounter, suggesting these proteins might provide new targets to ameliorate T cell responses in a variety of inflammatory states, including those associated with bone marrow or solid organ transplantation., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Once activated, T cells gain the ability to access both healthy and inflamed nonlymphoid tissues. They are then reactivated to remain in the tissue and exert their effector function only if they encounter their specific Ag. In this study, we set out to determine if the same is true for B cells using a mouse model of CNS autoimmunity that incorporates both T and B cell recognition of a myelin autoantigen. Both T and B cells were common infiltrates of spinal cords in diseased mice. However, unlike T cells, anti-myelin B cells were excluded from the inflamed tissue. Further, CNS B cells did not have a phenotype consistent with Ag-specific activation as it occurs in lymphatic tissue. Instead, they expressed elevated levels of CD80, indicating that B cells may contribute to local inflammation through nonantigen-specific mechanisms., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for hematologic and immunologic diseases. However, graft-versus-host disease (GVHD) may develop when donor-derived T cells recognize and damage genetically distinct normal host tissues. In addition to TCR signaling, costimulatory pathways are involved in T cell activation. CD27 is a TNFR family member expressed on T cells, and its ligand, CD70, is expressed on APCs. The CD27/CD70 costimulatory pathway was shown to be critical for T cell function and survival in viral infection models. However, the role of this pathway in allo-HCT is previously unknown. In this study, we have examined its contribution in GVHD pathogenesis. Surprisingly, Ab blockade of CD70 after allo-HCT significantly increases GVHD. Interestingly, whereas donor T cell- or bone marrow-derived CD70 plays no role in GVHD, host-derived CD70 inhibits GVHD as CD70 -/- hosts show significantly increased GVHD. This is evidenced by reduced survival, more severe weight loss, and increased histopathologic damage compared with wild-type hosts. In addition, CD70 -/- hosts have higher levels of proinflammatory cytokines TNF-α, IFN-γ, IL-2, and IL-17. Moreover, accumulation of donor CD4 + and CD8 + effector T cells is increased in CD70 -/- versus wild-type hosts. Mechanistic analyses suggest that CD70 expressed by host hematopoietic cells is involved in the control of alloreactive T cell apoptosis and expansion. Together, our findings demonstrate that host CD70 serves as a unique negative regulator of allogeneic T cell response by contributing to donor T cell apoptosis and inhibiting expansion of donor effector T cells., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Recent work investigating exercise induced changes in immunocompetence suggests that some of the ambiguity in the literature is resultant from different cell isolation protocols and mitogen selection. To understand this effect, we compared post-exercise measures of T cell activation and proliferation using two different stimulation methods (costimulation through CD28 or stimulation with phytohaemagglutinin [PHA]). Further, we investigated whether exercise induced changes are maintained when T cell isolation from whole blood is delayed overnight in either a room temperature or chilled (4°C) environment. As expected, an increased proliferation response was observed post-exercise in T cells isolated from whole blood of previously trained individuals immediately after blood collection. Also, cells stimulated with PHA after resting overnight in whole blood were not adversely impacted by the storage conditions. In contrast, allowing cells to rest overnight in whole blood prior to stimulation through CD28, lessened the proliferation observed by cells following exercise rendering both the room temperature and chilled samples closer to the results seen in the control condition. Changes in early markers of activation (CD25), followed a similar pattern, with activation in PHA stimulated cells remaining fairly robust after overnight storage; whereas cell activation following stimulation through CD3+CD28 was disproportionately decreased by the influence of overnight storage. These findings indicate that decisions regarding cell stimulation methods need to be paired with the timeline for T cell isolation from whole blood. These considerations will be especially important for field based studies of immunocompetence where there is a delay in getting whole blood samples to a lab for processing as well as clinical applications where a failure to isolate T cells in a timely manner may result in loss of the response of interest., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Compelling data suggest that lymphocyte depletion following T cell depleting therapy may induce prolonged CD4 T cell lymphopenia and trigger lymphocyte activation in some patients. These profound and non-reversible immune changes in T cell pool subsets are the consequence of both impaired thymic renewal and peripheral homeostatic proliferation. Chronic viral challenges by CMV play a major role in these immune alterations. Even when the consequences of CD4 T cell lymphopenia have been now well described, recent studies shed new light on the clinical consequences of immune activation. In this review, we will first focus on the mechanisms involved in T cell pool reconstitution after T cell depletion and further consider the clinical consequences of ATG-induced T cell activation and senescence in renal transplant recipients., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Schistosomiasis is a nontransplacental helminth infection. Chronic infection during pregnancy suppresses allergic airway responses in offspring. We addressed the question whether in utero exposure to chronic schistosome infection (Reg phase) in mice affects B-cell and T-cell development. Therefore, we focused our analyses on T-cell differentiation capacity induced by epigenetic changes in promoter regions of signature cytokines in offspring. Here, we show that naïve T cells from offspring of schistosome infected female mice had a strong capacity to differentiate into T H 1 cells, whereas T H 2 differentiation was impaired. In accordance, reduced levels of histone acetylation of the IL-4 promoter regions were observed in naïve T cells. To conclude, our mouse model revealed distinct epigenetic changes within the naïve T-cell compartment affecting T H 2 and T H 1 cell differentiation in offspring of mothers with chronic helminth infection. These findings could eventually help understand how helminths alter T-cell driven immune responses induced by allergens, bacterial or viral infections, as well as vaccines., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Germinal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture, which is consistent with recent studies. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls. Moreover, we found that the transcription factor BATF was transiently induced in LZ GC B cells in a Foxo1-dependent manner and that deletion of BATF similarly led to GC disruption. Thus, our results are consistent with a model where the switch from the LZ to the DZ is triggered after receipt of T cell help, and suggest that Foxo1-mediated BATF up-regulation is at least partly involved in this switch., (© 2017 Inoue et al.)

T-cell-mediated immune responses aim to protect mammals against cancers and infections, and are also involved in the pathogenesis of various inflammatory or autoimmune diseases. Cellular uptake and the utilization of nutrients is closely related to the T-cell fate decision and function. Research in this area has yielded surprising findings in the importance of amino-acid transporters for T-cell development, homeostasis, activation, differentiation and memory. In this review, we present current information on amino-acid transporters, such as LAT1 (l-leucine transporter), ASCT2 (l-glutamine transporter) and GAT-1 (γ-aminobutyric acid transporter-1), which are critically important for mediating peripheral naive T-cell homeostasis, activation and differentiation, especially for Th1 and Th17 cells, and even memory T cells. Mechanically, the influence of amino-acid transporters on T-cell fate decision may largely depend on the mechanistic target of rapamycin complex 1 (mTORC1) signaling. These discoveries remarkably demonstrate the role of amino-acid transporters in T-cell fate determination, and strongly indicate that manipulation of the amino-acid transporter-mTORC1 axis could ameliorate many inflammatory or autoimmune diseases associated with T-cell-based immune responses.

Plasmacytoid dendritic cells (pDCs) are known mainly for their secretion of type I IFN upon viral encounter. We describe a CD2 hi CD5 + CD81 + pDC subset, distinguished by prominent dendrites and a mature phenotype, in human blood, bone marrow, and tonsil, which can be generated from CD34 + progenitors. These CD2 hi CD5 + CD81 + cells express classical pDC markers, as well as the toll-like receptors that enable conventional pDCs to respond to viral infection. However, their gene expression profile is distinct, and they produce little or no type I IFN upon stimulation with CpG oligonucleotides, likely due to their diminished expression of IFN regulatory factor 7. A similar population of CD5 + CD81 + pDCs is present in mice and also does not produce type I IFN after CpG stimulation. In contrast to conventional CD5 - CD81 - pDCs, human CD5 + CD81 + pDCs are potent stimulators of B-cell activation and antibody production and strong inducers of T-cell proliferation and Treg formation. These findings reveal the presence of a discrete pDC population that does not produce type I IFN and yet mediates important immune functions previously attributed to all pDCs.

Type 2 phosphatidylinositol-5-phosphate 4-kinase (PI5P4K) converts phosphatidylinositol-5-phosphate to phosphatidylinositol-4,5-bisphosphate. Mammals have three enzymes PI5P4Kα, PI5P4Kβ, and PI5P4Kγ, and these enzymes have been implicated in metabolic control, growth control, and a variety of stress responses. Here, we show that mice with germline deletion of type 2 phosphatidylinositol-5-phosphate 4-kinase gamma (Pip4k2c), the gene encoding PI5P4Kγ, appear normal in regard to growth and viability but have increased inflammation and T-cell activation as they age. Immune cell infiltrates increased in Pip4k2c(-/-) mouse tissues. Also, there was an increase in proinflammatory cytokines, including IFNγ, interleukin 12, and interleukin 2 in plasma of Pip4k2c(-/-) mice. Pip4k2c(-/-) mice had an increase in T-helper-cell populations and a decrease in regulatory T-cell populations with increased proliferation of T cells. Interestingly, mammalian target of rapamycin complex 1 (mTORC1) signaling was hyperactivated in several tissues from Pip4k2c(-/-) mice and treating Pip4k2c(-/-) mice with rapamycin reduced the inflammatory phenotype, resulting in a decrease in mTORC1 signaling in tissues and a decrease in proinflammatory cytokines in plasma. These results indicate that PI5P4Kγ plays a role in the regulation of the immune system via mTORC1 signaling.

We conducted a case-controlled study of the associations of CCR5-Δ32 heterozygosity with human immunodeficiency virus type 1 (HIV-1) reservoir size, lymphocyte activation, and CCR5 expression in 114 CCR5(Δ32/WT) and 177 wild-type CCR5 AIDS Clinical Trials Group participants receiving suppressive antiretroviral therapy. Overall, no significant differences were found between groups for any of these parameters. However, higher levels of CCR5 expression correlated with lower amounts of cell-associated HIV-1 RNA. The relationship between CCR5-Δ32 heterozygosity, CCR5 expression, and markers of HIV-1 persistence is likely to be complex and may be influenced by factors such as the duration of ART., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Ion channels are crucially important for the activation and proliferation of T lymphocytes, and thus, for the function of the immune system. Previous studies on the effects of channel blockers on T cell proliferation reported variable effectiveness due to differing experimental systems. Therefore our aim was to investigate how the strength of the mitogenic stimulation influences the efficiency of cation channel blockers in inhibiting activation, cytokine secretion and proliferation of T cells under standardized conditions. Human peripheral blood lymphocytes were activated via monoclonal antibodies targeting the TCR-CD3 complex and the co-stimulator CD28. We applied the blockers of Kv1.3 (Anuroctoxin), KCa3.1 (TRAM-34) and CRAC (2-Apb) channels of T cells either alone or in combination with rapamycin, the inhibitor of the mammalian target of rapamycin (mTOR). Five days after the stimulation ELISA and flow cytometric measurements were performed to determine IL-10 and IFN-γ secretion, cellular viability and proliferation. Our results showed that ion channel blockers and rapamycin inhibit IL-10 and IFN-γ secretion and cell division in a dose-dependent manner. Simultaneous application of the blockers for each channel along with rapamycin was the most effective, indicating synergy among the various activation pathways. Upon increasing the extent of mitogenic stimulation the anti-proliferative effect of the ion channel blockers diminished. This phenomenon may be important in understanding the fine-tuning of T cell activation., (Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.)

It remains unclear how localized radiotherapy for cancer metastases can occasionally elicit a systemic antitumor effect, known as the abscopal effect, but historically, it has been speculated to reflect the generation of a host immunotherapeutic response. The ability to purposefully and reliably induce abscopal effects in metastatic tumors could meet many unmet clinical needs. Here, we describe a mathematical model that incorporates physiologic information about T-cell trafficking to estimate the distribution of focal therapy-activated T cells between metastatic lesions. We integrated a dynamic model of tumor-immune interactions with systemic T-cell trafficking patterns to simulate the development of metastases. In virtual case studies, we found that the dissemination of activated T cells among multiple metastatic sites is complex and not intuitively predictable. Furthermore, we show that not all metastatic sites participate in systemic immune surveillance equally, and therefore the success in triggering the abscopal effect depends, at least in part, on which metastatic site is selected for localized therapy. Moreover, simulations revealed that seeding new metastatic sites may accelerate the growth of the primary tumor, because T-cell responses are partially diverted to the developing metastases, but the removal of the primary tumor can also favor the rapid growth of preexisting metastatic lesions. Collectively, our work provides the framework to prospectively identify anatomically defined focal therapy targets that are most likely to trigger an immune-mediated abscopal response and therefore may inform personalized treatment strategies in patients with metastatic disease., (©2016 American Association for Cancer Research.)

The objective of this study was to investigate serum adenosine deaminase (ADA) activity as a marker of T lymphocyte activation and parameters of oxidative stress and antioxidant defence in hyperemesis gravidarum (HG). Serum ADA activity, malondialdehyde (MDA), catalase (CAT) and glutathione peroxidase (GPx) levels were investigated in 40 pregnant women with the HG and 40 with healthy pregnancies, in a descriptive study. Although serum ADA and CAT were measured to be higher in HG group, the difference was not significant. Serum MDA and GPx levels were significantly elevated in women with HG when compared with those without HG. The significance of changes in lipid peroxidation and T-cell activation in the pathogenesis of HG and whether this is a cause or a compensatory reaction to HG requires further investigations with larger multicentre trials.

Calcium ions (Ca(2+)) are a ubiquitous transducer of cellular signals controlling key processes such as proliferation, differentiation, secretion and metabolism. In the context of T cells, stimulation through the T cell receptor has been shown to induce the release of Ca(2+) from intracellular stores. This sudden elevation within the cytoplasm triggers the opening of ion channels in the plasma membrane allowing an influx of extracellular Ca(2+) that in turn activates key molecules such as calcineurin. This cascade ultimately results in gene transcription and changes in the cellular state. Traditional methods for measuring Ca(2+) include spectrophotometry, conventional flow cytometry (CFC) and live cell imaging techniques. While each method has strengths and weaknesses, none can offer a detailed picture of Ca(2+) mobilisation in response to various agonists. Here we report an Imaging Flow Cytometry (IFC)-based method that combines the throughput and statistical rigour of CFC with the spatial information of a microscope. By co-staining cells with Ca(2+) indicators and organelle-specific dyes we can address the spatiotemporal patterns of Ca(2+) flux in Jurkat cells after stimulation with anti-CD3. The multispectral, high-throughput nature of IFC means that the organelle co-staining functions to direct the measurement of Ca(2+) indicator fluorescence to either the endoplasmic reticulum (ER) or the mitochondrial compartments without the need to treat cells with detergents such as digitonin to eliminate cytoplasmic background. We have used this system to look at the cellular localisation of Ca(2+) after stimulating cells with CD3, thapsigargin or ionomycin in the presence or absence of extracellular Ca(2+). Our data suggest that there is a dynamic interplay between the ER and mitochondrial compartments and that mitochondria act as a sink for both intracellular and extracellular derived Ca(2+). Moreover, by generating an NFAT-GFP expressing Jurkat line, we were able to combine mitochondrial Ca(2+) measurements with nuclear translocation. In conclusion, this method enables the high throughput study of spatiotemporal patterns of Ca2(+) signals in T cells responding to different stimuli., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Regeneration of the immune system after hematopoietic stem cell transplantation (HSCT) is a slow process. We attempted to identify problems in the recovery of the immune system by examining expressions of early event cell cycle proteins Myc, Jun, and Fos, as well as DNA binding of Myc, activating protein 1 (AP-1), and CD4 cell activation values, in phytohemagglutinin-activated T lymphocytes taken from patients after HSCT. HSCT patients showed lower protein expression levels of Myc and Jun, as well as Myc and AP-1 DNA-binding levels, as compared to healthy controls. C-Jun was lower in long-term survivors of HSCT than short-term survivors. Adenosine triphosphate (ATP) values in CD4 cells were also lower in HSCT patients than healthy controls, but showed a time-dependent increase post-transplant. Non-surviving patients showed lower levels of both Fos protein and ATP as compared to surviving patients and a negative correlation between Fos values and lymphocyte percentage that was not present in surviving patients. There was a strong positive correlation between Fos values and lymphocyte percentage and between AP-1 values and white blood count, in patients without graft-versus-host disease (GVHD), that did not exist in patients who suffered from GVHD. Patients 2 years post-HSCT showed a positive correlation between AP-1 and Myc DNA-binding protein values, similar to those values found in healthy controls. Our study identified significant factors that account for the delay in immune reconstitution after transplant; this knowledge may improve the management of post-HSCT patients.

microRNAs (miRNAs) are a class of small non-coding RNAs acting as post-transcriptional regulators of gene expression and play fundamental roles in regulating immune response and autoimmunity. We show that memory T-lymphocytes express higher levels of miR-21 compared to naïve T-lymphocytes and that miR-21 expression is induced upon TCR engagement of naïve T-cells. We identify bona fide miR-21 targets by direct immuno-purification and profiling of AGO2-associated mRNAs in Jurkat cells over-expressing miR-21. Our analysis shows that, in T-lymphocytes, miR-21 targets genes are involved in signal transduction. Coherently, TCR signalling is dampened upon miR-21 over-expression in Jurkat cells, resulting in lower ERK phosphorylation, AP-1 activation and CD69 expression. Primary human lymphocytes in which we impaired miR-21 activity, display IFN-γ production enhancement and stronger activation in response to TCR engagement as assessed by CD69, OX40, CD25 and CD127 analysis. By intracellular staining of the endogenous protein in primary T-lymphocytes we validate three key regulators of lymphocyte activation as novel miR-21 targets. Our results highlight an unexpected function of miR-21 as a negative modulator of signal transduction downstream of TCR in T-lymphocytes., (Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: Traumatic brain injury (TBI), a significant cause of death and disability, causes, as in any injury, an acute, innate immune response. A key component in the transition between innate and adaptive immunity is the processing and presentation of antigen by professional antigen presenting cells (APCs). Whether an adaptive immune response to brain injury is beneficial or detrimental is not known. Current efforts to understand the contribution of the immune system after TBI have focused on neuroinflammation and brain-infiltrating immune cells. Here, we characterize and target TBI-induced expansion of peripheral immune cells that may act as potential APCs. Because MHC Class II-associated invariant peptide (CLIP) is important for antigen processing and presentation, we engineered a competitive antagonist (CAP) for CLIP, and tested the hypothesis that peptide competition could reverse or prevent neurodegeneration after TBI., Results: We show that after fluid percussion injury (FPI), peripheral splenic lymphocytes, including CD4+ and CD8+ T cells, regulatory T cells (Tregs), and γδ T cells, are increased in number within 24 hours after FPI. These increases were reversed by CAP treatment and this antagonism of CLIP also reduced neuroinflammation and neurodegeneration after TBI. Using a mouse deficient for the precursor of CLIP, CD74, we observed decreased peripheral lymphocyte activation, decreased neurodegeneration, and a significantly smaller lesion size following TBI., Conclusion: Taken together, the data support the hypothesis that neurodegeneration following TBI is dependent upon antigen processing and presentation that requires CD74.

The unsaponifiable fraction (UF) of extra virgin olive oil (EVOO) possesses anti-inflammatory properties and exerts preventative effects in murine models of inflammatory bowel disease (IBD). The present study was designed to determine the in vitro effects of UF on blood and intestinal T cells from IBD patients and healthy subjects. The T cell phenotype was investigated by flow cytometry and cytokine secretion was determined by ELISA. The presence of UF of EVOO promoted apoptosis and attenuated activation of intestinal and blood T cells isolated from IBD patients, decreasing the frequency of CD69(+) and CD25(+) T cells and, also, the secretion of IFN-γ. Moreover, UF reduced the expression of the gut homing receptor integrin β7 on blood T cells from IBD patients. In conclusion, UF modulates the activity and the gut homing capacity of T cells, and might therefore be considered as a dietary complement with an anti-inflammatory role in IBD patients., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Defining the association of non-AIDS-defining events with inflammation and immune activation among human immunodeficiency virus (HIV)-infected persons with antiretroviral therapy (ART)-associated virological suppression is critical to identifying interventions to decrease the occurrence of these events., Methods: We conducted a case-control study of HIV-infected subjects who had achieved virological suppression within 1 year after ART initiation. Cases were patients who experienced non-AIDS-defining events, defined as myocardial infarction, stroke, non-AIDS-defining cancer, non-AIDS-defining serious bacterial infection, or death. Controls were matched to cases on the basis of age, sex, pre-ART CD4(+) T-cell count, and ART regimen. Peripheral blood mononuclear cells and plasma specimens obtained at the visit before ART initiation (hereafter, baseline), the visit approximately 1 year after ART initiation (hereafter, year 1), and the visit immediately preceding the non-AIDS-defining event (hereafter, pre-event) were analyzed for activated CD4(+) and CD8(+) T cells, plasma interleukin 6 (IL-6) level, soluble tumor necrosis factor receptor I (sTNFR-I) level, sTNFR-II level, soluble CD14 level, kynurenine-to-tryptophan (KT) ratio, and D-dimer level. Conditional logistic regression analysis was used to study the association between biomarkers and outcomes, with adjustment for potential confounders., Results: Higher IL-6 level, sTNFR-I level, sTNFR-II level, KT ratio, and D-dimer level at year 1 were associated with the occurrence of a non-AIDS-defining event. Significant associations were also seen between non-AIDS-defining events and values of these biomarkers in specimens obtained at baseline and the pre-event time points. Effects remained significant after control for confounders. T-cell activation was not significantly related to outcomes., Conclusions: Interventional trials to decrease the incidence of non-AIDS-defining events among HIV-infected persons with virological suppression should consider targeting the pathways represented by these soluble markers. Clinical Trials Registration. NCT00001137., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

People may reach the upper limits of the human life span at least partly because they have maintained more appropriate immune function, avoiding changes to immunity termed "immunosenescence." Exceptionally long-lived people may be enriched for genes that contribute to their longevity, some of which may bear on immune function. Centenarian offspring would be expected to inherit some of these, which might be reflected in their resistance to immunosenescence, and contribute to their potential longevity. We have tested this hypothesis by comparing centenarian offspring with age-matched controls. We report differences in the numbers and proportions of both CD4(+) and CD8(+) early- and late-differentiated T cells, as well as potentially senescent CD8(+) T cells, suggesting that the adaptive T-cell arm of the immune system is more "youthful" in centenarian offspring than controls. This might reflect a superior ability to mount effective responses against newly encountered antigens and thus contribute to better protection against infection and to greater longevity.

Pontin is a chromatin remodeling factor that possesses both ATPase and DNA helicase activities. Based on high expression in lymphoid tissues, we examined whether Pontin has a T cell-specific function. We generated Pontin(f/f);Lck-Cre mice, in which Pontin can be conditionally deleted in T cells and then explored T cell-specific function of Pontin in vivo. Here, we show that specific abrogation of Pontin expression in T cells almost completely blocked development of αβ T cells at the β-selection checkpoint by inducing cell apoptosis indicating that Pontin is essential for early T cell development. Pontin-deficient thymocytes show a comparable expression level of T cell receptor (TCR)β chain, but have enhanced activation of p53 and Notch signaling compared to wild-type thymocytes. Intriguingly, the developmental block of αβ T cells can be partially rescued by loss of p53. Together, our data demonstrate a novel role of Pontin as a crucial regulator in pre-TCR signaling during T cell development., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Versican is an extracellular matrix (ECM) proteoglycan that interacts with cells by binding to non-integrin and integrin receptors and to other ECM components that associate with the cell surface. Recent studies have shown also that versican interacts with myeloid and lymphoid cells promoting their adhesion and production of inflammatory cytokines. Versican is produced by stromal cells, as well as leukocytes, and is markedly increased in inflammation. Inflammatory agonists, such as double-stranded RNA mimetics (e.g., poly I:C), stimulate stromal cells, smooth muscle cells and fibroblasts, to produce fibrillar ECMs enriched in versican and hyaluronan (HA) that interact with leukocytes promoting their adhesion. Interference with the incorporation of versican into this ECM blocks monocyte adhesion and dampens the inflammatory response. Tumor cells also express elevated levels of versican which interact with myeloid cells to promote an inflammatory response, through stimulating cytokine release, and metastasis. In addition, myeloid cells, such as macrophages in tumors, synthesize versican which affects tumor cell phenotypes, inflammation, and subsequent metastasis. Versican, by binding to hyaluronan, influences T lymphocyte phenotypes and in part controls the ability of these cells to synthesize and secrete cytokines that influence the immune response. Collectively, these studies indicate that versican as an ECM molecule plays a central role in inflammation and as a result it is emerging as a potential target promising wide therapeutic benefits., (Copyright © 2014 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.)

Following activation, T cells are released from lymph nodes to traffic via the blood to effector sites. The re-entry of these activated T cells into tissues represents a critical step for them to carry out local effector functions. Here we have assessed defects in effector T cells that are acutely depleted in Myosin-IIA (MyoIIA) and show a T cell intrinsic requirement for this motor to facilitate the diapedesis step of extravasation. We show that MyoIIA accumulates at the rear of T cells undergoing trans-endothelial migration. T cells can extend protrusions and project a substantial portion of their cytoplasm through the endothelial wall in the absence of MyoIIA. However, this motor protein plays a crucial role in allowing T cells to complete the movement of their relatively rigid nucleus through the endothelial junctions. In vivo, this defect manifests as poor entry into lymph nodes, tumors and into the spinal cord, during tissue-specific autoimmunity, but not the spleen. This suggests that therapeutic targeting of this molecule may allow for differential attenuation of tissue-specific inflammatory responses.

Background: Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections induce robust, generalized inflammatory responses that begin during acute infection and lead to pathological systemic immune activation, fibrotic damage of lymphoid tissues, and CD4⁺ T-cell loss, pathogenic processes that contribute to disease progression., Methods: To better understand the contribution of tumor necrosis factor (TNF), a key regulator of acute inflammation, to lentiviral pathogenesis, rhesus macaques newly infected with SIVmac239 were treated for 12 weeks in a pilot study with adalimumab (Humira), a human anti-TNF monoclonal antibody., Results: Adalimumab did not affect plasma SIV RNA levels or measures of T-cell immune activation (CD38 or Ki67) in peripheral blood or lymph node T cells. However, compared with untreated rhesus macaques, adalimumab-treated rhesus macaques showed attenuated expression of proinflammatory genes, decreased infiltration of polymorphonuclear cells into the T-cell zone of lymphoid tissues, and weaker antiinflammatory regulatory responses to SIV infection (ie, fewer presumed alternatively activated [ie, CD163⁺] macrophages, interleukin 10-producing cells, and transforming growth factor β-producing cells), along with reduced lymphoid tissue fibrosis and better preservation of CD4⁺ T cells., Conclusions: While HIV/SIV replication drives pathogenesis, these data emphasize the contribution of the inflammatory response to lentiviral infection to overall pathogenesis, and they suggest that early modulation of the inflammatory response may help attenuate disease progression.

Activated T cells have classically been thought to progress unidirectionally through discrete phenotypic states and differentiate into static lineages. It is increasingly evident, however, that T cells exhibit much more complex and flexible dynamic behaviors than initially appreciated, and that these behaviors influence the efficacy of T cell responses to immunological challenges. In this review, we discuss how new technologies for monitoring the dynamics of T cells are enhancing the resolution of the fine phenotypic and functional heterogeneity within populations of T cells and revealing how individual T cells transition among a continuum of states. Such insights into the dynamic properties of T cells should improve immune monitoring and inform strategies for therapeutic interventions., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the effects of T-cell-derived cytokines on gene and protein expression of chemokines in a human RPE cell line (ARPE-19)., Methods: We used an in vitro coculture system in which the RPE and CD3/CD28-activated T-cells were separated by a membrane. RPE cell expression of chemokine genes was quantified using three different types of microarrays. Protein expression was determined by single and multiplex ELISA and immunoblotting., Results: Coculture with activated T-cells increased RPE mRNA and protein expression of chemokines CCL2 (MCP-1); CCL5 (RANTES); CCL7 (MCP-3); CCL8 (MCP-2); CXCL1 (GRO-α); IL8 (CXCL8); CXCL9 (MIG); CXCL10 (IP10); CXCL11 (ITAC); and CX3CL1 (fractalkine). CCL7, CXCL9, CXCL10, and CXCL11 were secreted significantly more in the apical direction. Using recombinant human cytokines and neutralizing antibodies, we identified IFNγ and TNFα as the two major T-cell-derived cytokines responsible for the RPE response. For CCL5, CXCL9, CXCL10, CXCL11, CXCL16, and CX3CL1, we observed a synergistic effect of IFNγ and TNFα in combination. CCL20, CXCL1, CXCL6, and IL8 were negatively regulated by IFNγ., Conclusions: RPE cells responded to exposure to T-cell-derived cytokines by upregulating expression of multiple chemokines related to microglial, T-cell, and monocyte chemotaxis and activation. This inflammatory stress response may have implications for immune homeostasis in the retina, and for the further understanding of inflammatory ocular diseases such as uveitis and AMD.

We have previously reported that functionally active μ-opioid receptors (MOR) are constitutively expressed at relatively low levels by developing T cells in the thymus. However, very little is known about the regulation of MOR expression by immature T cells. In this report, we first attempted to determine the effect of T cell receptor-induced T cell activation on the expression of MOR. We activated T cells with either the combination of anti-CD3 and CD28, or with superantigen, and observed a substantial increase in MOR transcript expression. We also chose to examine the effect of cytokine-mediated T cell activation on the expression of this opioid receptor. We selected certain cytokines that play a role in T cell development and are known to be present at functional levels in the thymus gland. Our results show that interferon γ (IFNγ), IL-1β, and IL-2, and in particular transforming growth factor-β (TGFβ), all induced significant increases in MOR transcript expression. On the other hand, both TNFα and IL-7 exhibited much weaker effects on MOR expression. These results show that MOR expression by developing T cells is strongly regulated by several cytokines involved in T cell development in the thymus gland.

Many of the receptors which are responsible for the responses to the common drugs of abuse belong to the G protein-coupled receptor (GPCR) family. In this special issue of the Journal of Neuroimmune Pharmacology a collection of papers is presented which deals with signaling events that are important for the function of these receptors. Because these receptors are expressed by both neuronal and immune cells, and because these receptors play a complex role in regulating function in both the nervous and immune systems, a more complete understanding of the regulation of expression of these receptors is essential. Moreover, once these receptors are expressed and activated, a complex series of signaling events are initiated that can have substantial significance. We have only a limited understanding of these signaling events, but with more complete information, we may be able to control the undesirable and/or desirable consequences of receptor activation by drugs of abuse.

Background: Human induced pluripotent stem cells (iPSCs) possess remarkable self-renewal capacity and the potential to differentiate into novel cell types, such as mesenchymal stem cells (MSCs). iPSC-MSCs have been shown to enhance tissue regeneration and attenuate tissue ischaemia; however, their contribution to the immune regulation of Th2-skewed allergic rhinitis (AR) and asthma remains unclear., Objective: This study compared the immunomodulatory effects of iPSC-MSCs and bone marrow-derived MSCs (BM-MSCs) on lymphocyte proliferation, T-cell phenotypes and cytokine production in peripheral blood mononuclear cells (PBMCs) in patients with AR, and investigated the possible molecular mechanisms underlying the immunomodulatory properties of iPSC-MSCs., Methods: In co-cultures of PBMCs with iPSC-MSCs or BM-MSCs, lymphocyte proliferation was evaluated using 3H-thymidine (3H-TdR) uptake, carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE) assays; the regulatory T-cell (Treg) phenotype was determined by flow cytometry, and cytokine levels were measured using an enzyme-linked immunosorbent assay. The immunomodulatory properties of both MSCs were further evaluated using NS398 and transwell experiments., Results: Similar to BM-MSCs, we determined that iPSC-MSCs significantly inhibit lymphocyte proliferation and promote Treg response in PBMCs (P < 0.05). Accordingly, the cytokine milieu (IFN-γ, IL-4, IL-5, IL-10 and IL-13) in the supernatants of PBMCs changed significantly (P < 0.05). The immunomodulatory properties of iPSC-MSCs and BM-MSCs were associated with prostaglandin E2 (PGE2) production and cell-cell contact., Conclusions: These data demonstrate that iPSC-MSCs are capable of modulating T-cell phenotypes towards Th2 suppression through inducing Treg expansion, suggesting that iPSC-MSCs can be used as an alternative candidate to adult MSCs to treat allergic airway diseases., (© 2012 John Wiley & Sons A/S.)

Allergic contact dermatitis is the quintessential example of a delayed-in-time and T-cell-mediated immune response. In the last decade, many of the molecular events required to initiate (or block) such a response have been uncovered. Textbook and journal reviews have emphasized the costimulatory requirements, with less focus on the coinhibitory signals that are of equal importance in understanding this central event of adaptive immunity. To fill this gap, we offer a compendium of discoveries characterizing the ligand-receptor pairs inhibiting T-cell activation and of selected illnesses and therapeutic applications that illuminate their role in health and disease.