Regulatory T cells constrain the TCR repertoire of antigen‐stimulated conventional CD4 T cells

To analyze the potential role of Tregs in controlling the TCR repertoire breadth to a non‐self‐antigen, a TCRβ transgenic mouse model (EF4.1) expressing a limited, yet polyclonal naïve T‐cell repertoire was used. The response of EF4.1 mice to an I‐Ab‐associated epitope of the F‐MuLV envelope protein is dominated by clones expressing a Vα2 gene segment, thus allowing a comprehensive analysis of the TCRα repertoire in a relatively large cohort of mice. Control and Treg‐depleted EF4.1 mice were immunized, and the extent of the Vα2‐bearing, antigen‐specific TCR repertoire was characterized by high‐throughput sequencing and spectratyping analysis. In addition to increased clonal expansion and acquisition of effector functions, Treg depletion led to the expression of a more diverse TCR repertoire comprising several private clonotypes rarely observed in control mice or in the pre‐immune repertoire. Injection of anti‐CD86 antibodies in vivo led to a strong reduction in TCR diversity, suggesting that Tregs may influence TCR repertoire diversity by modulating costimulatory molecule availability. Collectively, these studies illustrate an additional mechanism whereby Tregs control the immune response to non‐self‐antigens.     

树突状表皮T细胞在胸腺内发育的研究进展

树突状表皮T淋巴细胞(DETC),特异性分布在表皮组织内,在皮肤免疫监视,皮肤伤面愈合中发挥重要作用.小鼠DETC发育仅涉及胚胎14.5 ～ 18 d这一短暂时间窗,而后则不再产生这类细胞.本综述拟从DETC T细胞受体(TCR)基因重排特点及调控机制,DETC在胸腺中的阳性选择及调控机制等方面进行论述,以期对DETC...     

Cytotoxic activity and T cell receptor repertoire in tumor-infiltrating lymphocytes of adrenal cell carcinomas

The cytotoxic activity and T cell receptor (TCR) V repertoire in tumor-infiltrating lymphocytes (TIL) of three primary adrenal cell carcinomas were analyzed. Fresh, non-cultured TIL from two of the three tumors showed low but significant lysis of the autologous tumor, and for one of the patients this activity was strongly enhanced upon culture in interleukin-2. An allogeneic adrenal cell carcinoma line and the K562 or Daudi targets included as controls were not killed. Phenotypic analysis of freshly isolated TIL demonstrated that the cells from the two patients that demonstrated cytolytic capacity mainly consisted of CD45RO⁺ T cells. In vitro cultured TIL lines from these patients demonstrated a high percentage of CD8⁺ cells expressing either the V6 gene or the V8 gene product, as measured with a panel of mAb specific for TCR V and V gene products. Analysis of the TCR V gene mRNA expression in freshly isolated non-cultured TIL, using a polymerase-chain-reaction-assisted cDNA-amplification assay, confirmed the strong expression of the genes coding for the TCR V6 or the V8. This assay also demonstrated a more restricted TCR V gene usage in the TIL as compared to peripheral blood lymphocytes from the same patient.This study was supported by the Swedish Cancer Society and by the Cancer Society in Stockholm     

Vdelta1 T cell receptor binds specifically to MHC I chain related A: molecular and biochemical evidences

Human MHC class I chain-related A (MICA) is a tumor-associated antigen that can be recognized by Vdelta1 subset of tumor-infiltrating gammadelta T cells. We previously reported that immobilized recombinant MICA protein could induce the proliferation of tumor-infiltrating Vdelta1 gammadelta T cells in vitro. But there has been no direct evidence showing the engagement of gammadelta T cell receptors (TCR) of the induced cells with MICA. In the current investigation, we show that MICA induces specific cytolytic activity of the expanded gammadelta T cells. We expressed the coupled V domains from the MICA-induced T cells as a single polypeptide chain Vdelta Vgamma TCR (gammadelta scTCR). Such scTCR can specifically bind MICA of HeLa cells. Direct interaction of gammadelta scTCRs with in vitro expressed MICA was monitored using an IAsys biosensor. We found that the Vdelta1 scTCR can specifically bind to immobilized MICA molecule and MICA alpha1alpha2 domains are responsible for the binding reaction.     

T cells are crucial for the anti-metastatic effect of anti-epidermal growth factor receptor antibodies

Experimental evidences supporting the epidermal growth factor receptor (EGFR) as an important molecule for tumor metastasis had been accumulated. Currently, anti-EGFR monoclonal antibodies (mAbs) constitute a promising approach for the treatment of patients with metastatic tumors. However, the mechanisms associated with the potent anti-metastatic effect of these mAbs have not been completely elucidated due to the lack of appropriate syngeneic preclinical models. In this paper, we have investigated the effects of 7A7, an antibody specific to murine EGFR, on the metastatic properties of D122 murine lung carcinoma. 7A7 mAb significantly impaired metastatic spread of D122 cells in C57BL/6 mice by direct anti-proliferative and pro-apoptotic effects on tumor metastasis. 7A7 mAb capacity to inhibit EGFR activation on D122 cells could contribute to its anti-metastatic effect. In addition, 7A7 mAb was able to induce in vitro antibody-dependent cell-mediated cytotoxicity on D122 cells. Interestingly, 7A7 mAb treatment increased the number of natural killer cells, T lymphocytes and dendritic cells infiltrating the metastatic sites. More strikingly, depletion of CD8⁺ and CD4⁺ T cells in vivo completely abrogated the 7A7 mAb anti-metastatic activity whereas function of natural killer cells was irrelevant. This study supports an in vivo role for T cell response in the mechanism of action of anti-EGFR mAbs, suggesting the induction of an adjuvant effect. This work was supported by the Cuban Government.     

T cell receptor-mediated signaling induces GRP78 expression in T cells: the implications in maintaining T cell viability

The 78-kDa glucose-regulated protein (GRP78) is an important molecular chaperone in the endoplasmic reticulum (ER) induced by various stresses. This study showed that stimulation with anti-CD3 mAb, PMA plus ionomycin, or an antigen increased the levels of GRP78 mRNA in primary T cells, which was inhibited by Ca²⁺ chelators EGTA and BAPTA-AM and by an inhibitor of calcineurin FK506. In addition, the specific knockdown of GRP78 protein expression induced apoptosis in mouse EL-4 T cell line associated with CHOP induction and caspase-3 activation. Furthermore, overexpression of GRP78 inhibited PMA/ionomycin-induced cell death in EL-4 cells. Collectively, GRP78 expression is induced by TCR activation via a Ca²⁺-dependent pathway and may play a critical role in maintaining T cell viability in the steady and TCR-activated states. These results suggest a novel regulatory mechanism and an essential function of GRP78 in T cells.     

Cancer of the gastrointestinal tract results in a restricted T-cell repertoire dependent upon tumor differentiation

We investigated the influence of tumor tissue differentiation on the diversity of TCR repertoire. CDR3 spectratypes of CD4⁺ and CD8⁺ T cell subsets were analyzed from 27 patients with gastrointestinal tract tumors exhibiting varying degrees of differentiation. A CDR3 spectratype complexity scoring system was used to quantify the diversity of TCR repertoire. Each patient was matched with an age-matched healthy group to control for age variability. Results show that the complexity scores (TCR repertoire diversity) have a significant correlation with the degree of tumor differentiation, which provides useful information for understanding immune response in cancer patients.     

Neurokinin-1 Receptor Signaling Is Required for Efficient Ca2+ Flux in T-Cell-Receptor-Activated T Cells

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T cell receptor repertoire of CD4+ and CD8+ T cell subsets in the allogeneic bone marrow transplant recipient

Allogeneic bone marrow transplantation (BMT) has become a therapy of choice for the treatment of certain malignancies and hematopoietic disorders. However, immunodeficiencies following BMT continue to cause significant morbidity and mortality. We have compared the T cell receptor (TCR) repertoire of BMT patients and healthy control individuals by staining peripheral blood mononuclear cells with fluorochrome-labeled TCR-specific antibodies. Several patients exhibited a biased pattern of TCR expression atypical of the healthy controls, yet no particular TCR bias characterized all patients. For example, we found that 2%–8% of T cell from healthy individuals expressed the V19 TCR. One BMT patient exhibited V19 expression on more than 60% of peripheral T cells, while additional patients expressed V19 on less than 1% of T cells. The patients with the most extreme skewing of TCR types suffered from graft-versus-host disease. The causes of skewed TCR V expression patterns in BMT patients are not fully understood, yet some researchers have suggested that an oligoclonal expansion of CD8⁺ T cell populations may be largely responsible. To test this hypothesis, we examined the TCR V repertoire of CD4⁺ and CD8⁺ T cell populations. We found that biased V expression characterized both CD4⁺ and CD8⁺ T cell populations, sometimes within a single individual. Thus, therapies directed toward CD8⁺ T cells alone may not fully correct repertoire abnormalities following BMT.     

Mushroom acidic glycosphingolipid induction of cytokine secretion from murine T cells and proliferation of NK1.1 alpha/beta TCR-double positive cells in vitro

Interferon (IFN)-γ and interleukin (IL)-4 regulate many types of immune responses. Here we report that acidic glycosphingolipids (AGLs) of Hypsizigus marmoreus and Pleurotus eryngii induced secretion of IFN- γ and IL-4 from T cells in a CD11c-positive cell-dependent manner similar to that of α-galactosylceramide (α-GalCer) and isoglobotriaosylceramide (iGb3), although activated T cells by AGLs showed less secretion of cytokine than those activated by α-GalCer. In addition, stimulation of these mushroom AGLs induced proliferation of NK1.1 α/β TCR-double positive cells in splenocytes. Administration of a mixture of α-GalCer and AGLs affected the stimulation of α-GalCer and generally induced a subtle Th1 bias for splenocytes but induced an extreme Th2 bias for thymocytes. These results suggested that edible mushroom AGLs contribute to immunomodulation.     

Differential requirements for proliferation of CD4+ and gammadelta+ T cells to spirochetal antigens

Alphabeta+ and gammadelta+ T cells have different mechanisms of epitope recognition and are stimulated by antigens of different chemical nature. An immunization model with antigens from the spirochete Brachyspira hyodysenteriae was used to examine the requirements for proliferation of circulating porcine CD4+ and gammadelta+ T cells in mixed lymphocyte cultures. CD4+ T cells only responded to stimulation with B. hyodysenteriae antigens, whereas gammadelta+ T cells proliferated when cultures were stimulated with either spirochetal antigens or interleukin-2 (IL-2). T cells that had proliferated expressed high levels of IL-2-receptor-alpha (IL-2Ralpha). Furthermore, neutralization of IL-2 at the beginning of the culture period was more efficient in blocking gammadelta+ than CD4+ T cell proliferation. Immunization induced interferon-gamma (IFN-gamma) production by CD4+ T cells, whereas only a small fraction of the antigen-stimulated gammadelta+ T cells produced this cytokine. Our results indicate that, under the same environmental conditions, CD4+ T cell functions are more tightly regulated when compared to gammadelta+ T cells. We conclude that these differences are due, in part, to the enhanced gammadelta+ T cell responsiveness to IL-2.     

T cell receptor recognition via cooperative conformational plasticity

Although T cell receptor cross-reactivity is a fundamental property of the immune system and is implicated in numerous autoimmune pathologies, the molecular mechanisms by which T cell receptors can recognize and respond to diverse ligands are incompletely understood. In the current study we examined the response of the human T cell lymphotropic virus-1 (HTLV-1) Tax-specific T cell receptor (TCR) A6 to a panel of structurally distinct haptens coupled to the Tax 11-19 peptide with a lysine substitution at position 5 (Tax5K, LLFG[K-hapten]PVYV). The A6 TCR could cross-reactively recognize one of these haptenated peptides, Tax-5K-4-(3-Indolyl)-butyric acid (IBA), presented by HLA-A*0201. The crystal structures of Tax5K-IBA/HLA-A2 free and in complex with A6 reveal that binding is mediated by a mechanism of cooperative conformational plasticity involving conformational changes on both sides of the protein-protein interface, including the TCR complementarity determining region (CDR) loops, Valpha/Vbeta domain orientation, and the hapten-modified peptide. Our findings illustrate the complex role that protein dynamics can play in TCR cross-reactivity and highlight that T cell receptor recognition of ligand can be achieved through diverse and complex molecular mechanisms that can occur simultaneously in the interface, not limited to molecular mimicry and CDR loop shifts.     

Regulatory KIR+RA+ T cells accumulate with age and are highly activated during viral respiratory disease

Severe respiratory viral infectious diseases such as influenza and COVID‐19 especially affect the older population. This is partly ascribed to diminished CD8⁺ T‐cell responses a result of aging. The phenotypical diversity of the CD8⁺ T‐cell population has made it difficult to identify the impact of aging on CD8⁺ T‐cell subsets associated with diminished CD8⁺ T‐cell responses. Here we identify a novel human CD8⁺ T‐cell subset characterized by expression of Killer‐cell Immunoglobulin‐like Receptors (KIR⁺) and CD45RA (RA⁺). These KIR⁺RA⁺ T cells accumulated with age in the blood of healthy individuals (20–82 years of age, n = 50), expressed high levels of aging‐related markers of T‐cell regulation, and were functionally capable of suppressing proliferation of other CD8⁺ T cells. Moreover, KIR⁺RA⁺ T cells were a major T‐cell subset becoming activated in older adults suffering from an acute respiratory viral infection (n = 36), including coronavirus and influenza virus infection. In addition, older adults with influenza A infection showed that higher activation status of their KIR⁺RA⁺ T cells associated with longer duration of respiratory symptoms. Together, our data indicate that KIR⁺RA⁺ T cells are a unique human T‐cell subset with regulatory properties that may explain susceptibility to viral respiratory disease at old age.     

Cross-primed CD8+ cytotoxic T cells induce severe Helicobacter-associated gastritis in the absence of CD4+ T cells

BACKGROUND: Although previous studies have reported important roles of CD4(+) type 1-helper T cells and regulatory T cells in Helicobacter-associated gastritis, the significance of CD8(+) cytotoxic T cells remains unknown. To study the roles of CD8(+) T cells, we examined the immune response in the gastric mucosa of Helicobacter felis-infected major histocompatibility complex (MHC) class II-deficient (II(-/-)) mice, which lack CD4(+) T cells. MATERIALS AND METHODS: Stomachs from H. felis-infected wild-type and infected MHC II(-/-) mice were examined histologically and immunohistochemically. Gastric acidity and serum levels of anti-H. felis antibodies were measured. The expression of pro-inflammatory and anti-inflammatory cytokine, Fas-ligand, perforin, and Foxp3 genes in the gastric mucosa was investigated. RESULTS: H. felis-infected MHC II(-/-) mice developed severe gastritis, accompanied by marked infiltration of CD8(+) cells. At 1 and 2 months after inoculation, mucosal inflammation and atrophy were more severe in MHC II(-/-) mice, although gastritis had reached similar advanced stages at 3 months after inoculation. There was little infiltration of CD4(+) cells, and no Foxp3-positive cells were detected in the gastric mucosa of the infected MHC II(-/-) mice. The expression of the interleukin-1beta and Fas-ligand genes was up regulated, but that of Foxp3 was down regulated in the infected MHC II(-/-) mice. Serum levels of anti-H. felis antibodies were lower in the infected MHC II(-/-) mice, despite severe gastritis. CONCLUSIONS: The present study suggests that cross-primed CD8(+) cytotoxic T cells can induce severe H.-associated gastritis in the absence of CD4(+) helper T cells and that Foxp3-positive cells may have an important role in the control of gastric inflammation.     

Engineering T cells for immunotherapy of primary human hepatocellular carcinoma

Liver cancers, majority of which are primary hepatocellular carcinoma(HCC), continue to be on the rise in the world. Furthermore, due to the lack of effective treatments, liver cancer ranks the 4~(th) most common cause of male cancer deaths. Novel therapies are urgently needed. Over the last few years,immunotherapies, especially the checkpoint blockades and adoptive cell therapies of engineered T cells,have demonstrated a great potential for treating malignant tumors including HCC. In this review, we summarize the current ongoing research of antigen-specific immunotherapies including cancer vaccines and adoptive cell therapies for HCC. We briefly discuss the HCC cancer vaccine and then focus on the antigen-specific T cells genetically engineered with the T cell receptor genes(TCRTs) and the chimeric antigen receptor genes(CARTs). We first review the current options of TCRTs and CARTs immunotherapies for HCC, and then analyze the factors and parameters that may help to improve the design of TCRTs and CARTs to enhance their antitumor efficacy and safety. Our goals are to render readers a panoramic view of the current stand of HCC immunotherapies and provide some strategies to design better TCRTs and CARTs to achieve more effective and durable antitumor effects.     

Roles of TRAF3 in T cells: many surprises

Tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) is broadly involved in different receptor-mediated signaling pathways. Considerable progress was made recently in understanding the role of TRAF3 in T cell biology. Here we review these new findings about how TRAF3 participates in T cell development and function. The different roles of TRAF3 in distinct immune cells are also compared. That TRAF3 is required for T cell effector functions, and invariant Natural Killer T cell function and development, was unexpected. Another surprising finding is that TRAF3 normally restrains regulatory T cell development. It is now clear that TRAF3 regulates signaling to T cells not only through costimulatory members of the TNFR superfamily, but also through the T cell receptor complex, and cytokine receptors. The diverse roles it plays support the multifaceted nature of this molecule. How TRAF3 mediates integration of different signaling cascades is an important topic for future study.     

Aging impacts CD103+CD8+ T cell presence and induction by dendritic cells in the genital tract

As women age, susceptibility to systemic and genital infections increases. Tissue‐resident memory T cells (TRMs) are CD103⁺CD8⁺ long‐lived lymphocytes that provide critical mucosal immune protection. Mucosal dendritic cells (DCs) are known to induce CD103 expression on CD8⁺ T cells. While CD103⁺CD8⁺ T cells are found throughout the female reproductive tract (FRT), the extent to which aging impacts their presence and induction by DCs remains unknown. Using hysterectomy tissues, we found that endometrial CD103⁺CD8⁺ T cells were increased in postmenopausal compared to premenopausal women. Endometrial DCs from postmenopausal women were significantly more effective at inducing CD103 expression on allogeneic naïve CD8⁺ T cells than DCs from premenopausal women; CD103 upregulation was mediated through membrane‐bound TGFβ signaling. In contrast, cervical CD103⁺ T cells and DC numbers declined in postmenopausal women with age. Decreases in DCs correlated with decreased CD103⁺ T cells in endocervix, but not ectocervix. Our findings demonstrate a previously unrecognized compartmentalization of TRMs in the FRT of postmenopausal women, with loss of TRMs and DCs in the cervix with aging, and increased TRMs and DC induction capacity in the endometrium. These findings are relevant to understanding immune protection in the FRT and to the design of vaccines for women of all ages.     

Regulation of growth and survival of activated T cells by cell-transducing inhibitors of Ras

We describe the development of cell-penetrating inhibitors of Ras and study their ability to inhibit T cell activation. The inhibitors transduced T cells in a time and concentration-dependent manner and interacted with endogenous Ras. Anti-CD3/CD28-activated cells when treated with the inhibitors, exhibited a notable reduction in cell size, diminished proliferative capacity, and were more prone to apoptosis. Similarly, lymphocytes activated by antigen in vivo, exhibited accelerated apoptosis when treated with the inhibitors ex vivo. Our data reveal a pro-survival role for Ras in activated primary T cells and describe a new methodology for regulating its activity.

Structured summary

MINT-6802882: RAF1 (uniprotkb:P04049) physically interacts (MI:0218) with RAS (uniprotkb:P01112) by anti tag co-immunoprecipitation (MI:0007)