Identification of a previously unknown antigen-specific regulatory T cell and its mechanism of suppression

The immunogenicity and protective immunity of multi-epitopes DNA prime-protein boost vaccines encoding Amastin-Kmp-11, Kmp11-Gp63 and Amastin-Gp63 against visceral leishmaniasis

Visceral leishmaniasis (VL) is the most fatal form of leishmaniasis if left untreated and 50,000 to 90,000 new cases of VL occur worldwide each year. Although various vaccines had been studied in animal models, none of them was eligible to prevent human from infections. In this study, according to the silico analysis of Leishmania Amastin, Kmp-11 and Gp63 protein, dominant epitope sequences of these proteins were selected and linked to construct dominant multi-epitopes DNA and protein vaccines (Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63) against VL. BALB/c mice were immunized with a DNA prime-protein boost immunization strategy and challenged with a new Leishmania parasite strain isolated from a VL patient. After immunization, the results including specific antibody titers, IL-4 and TNF-α levels, and CD4 and CD8 T cell proportion suggested the potent immunogenicity of the three vaccines. After infection, the results of spleen parasite burdens in the three vaccine groups were significantly lower than those of control groups, and the parasite reduction rates of Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63 groups were 89.38%, 91.01% and 88.42%, respectively. Spleen smear observation and liver histopathological changes showed that all vaccine groups could produce significant immunoprotection against VL and Amastin-Gp63 vaccine was the best. In conclusion, our work demonstrated that the three dominant multi-epitopes Amastin-Kmp-11, Amastin-Gp63 and Kmp-11-Gp63 DNA prime-protein boost vaccines might be new vaccine candidates for VL, and the Amastin-Gp63 vaccine have best efficacy.

TCR-α/β CD4- CD8- double negative T cells arise from CD8+ T cells

The cellular origin of CD4^- CD8^- (double negative, DNT) TCR-α/β⁺ T cells remains unknown. Available evidence indicates that they may derive from CD8⁺ T cells, but most published data have been obtained using cells that bear an invariant transgenic T cell receptor that recognizes an Ag that is not present in normal mice. Here, we have used complementary fate mapping and adoptive transfer experiments to identify the cellular lineage of origin of DNT cells in wild-type mice with a polyclonal T cell repertoire. We show that TCR-α/β⁺ DNT cells can be traced back to CD8⁺ and CD4⁺ CD8⁺ double positive cells in the thymus. We also demonstrate that polyclonal DNT cells generated in secondary lymphoid organs proliferate upon adoptive transfer and can regain CD8 expression in lymphopenic environment. These results demonstrate the cellular origin of DNT cells and provide a conceptual framework to understand their presence in pathological circumstances.

Case Report: Clinical and Immunological Features of a Chinese Cohort With Mycoplasma-Induced Rash and Mucositis

Dermatological disorders are the most common extrapulmonary complications of Mycoplasma pneumoniae, of which Mycoplasma-induced rash and mucositis (MIRM) has recently been proposed to be a separate diagnostic entity. MIRM could easily be misdiagnosed as atypical Stevens-Johnson syndrome by clinicians due to the unawareness of this rare disease. We retrospectively reviewed the inpatient database from Jan. 2016 to Dec. 2019 of the Children's Hospital of Fudan University. In total, five patients (mean age 5.5 years, three male) matched the diagnostic criteria of MIRM. All patients had scattered lesions and more than two sites of mucosal involvement. The serum IgA level of three patients was higher than normal. Two patients had a significant decrease in peripheral blood CD3+ T and CD4+ T cells that improved with recovery. The percentage of TCRαβ+ CD4-CD8-T cells of Patient five was higher than normal. All patients received treatments with antibiotics and corticosteroids, 3 patients received intravenous immunoglobulin. Among five patients, three patients complained of dyspigmentation, and two patients had an uneventful recovery. MIRM is a separate entity with predominant mucosal involvement and excellent prognosis that more often affects younger patients. Excessive inflammatory reactions may lead to immune disorders, including lymphopenia and a redistribution of CD4+ T cells. We recommend that pneumonia accompanied by mucocutaneous eruptions, especially in young patients, should raise clinical suspicion of MIRM.

Distinct Features of Canine Non-conventional CD4-CD8α- Double-Negative TCRαβ+ vs. TCRγδ+ T Cells

The role of conventional TCRαβ⁺CD4⁺ or TCRαβ⁺CD8α⁺ single-positive (sp) T lymphocytes in adaptive immunity is well-recognized. However, non-conventional T cells expressing TCRαβ or TCRγδ but lacking CD4 and CD8α expression [i.e., CD4⁻CD8α⁻ double-negative (dn) T cells] are thought to play a role at the interface between the innate and adaptive immune system. Dn T cells are frequent in swine, cattle or sheep and predominantly express TCRγδ. In contrast, TCRγδ⁺ T cells are rare in dogs. In this study, we identified a high proportion of canine dn T cells in the TCRαβ⁺ T cell population of PBMC, lymphatic and non-lymphatic organs. In PBMC, the frequency of this T cell subpopulation made up one third of the frequency of TCRαβ⁺CD4⁺ sp, and almost half of the frequency of TCRαβ⁺CD8α⁺ sp T cells (i.e., ~15% of all TCRαβ⁺ T cells). Among TCRαβ⁺CD4⁻CD8α⁻ dn T cells of PBMC and tissues, FoxP3⁺ cells were identified indicating regulatory potential of this T cell subset. 80% of peripheral blood FoxP3⁺TCRαβ⁺CD4⁻CD8α⁻ dn T cells co-expressed CD25, and, interestingly, also the FoxP3-negative TCRαβ⁺CD4⁻CD8α⁻ dn T cells comprised ~34% CD25⁺ cells. Some of the FoxP3-positive TCRαβ⁺CD4⁻CD8α⁻ dn T cells co-expressed GATA-3 suggesting stable function of regulatory T cells. The frequency of GATA-3 expression by FoxP3⁻TCRαβ⁺CD4⁻CD8α⁻ dn T cells was even higher as compared with TCRαβ⁺CD4⁺ sp T cells (20.6% vs. 11.9%). Albeit lacking FoxP3 and CD25 expression, TCRγδ⁺CD4⁻CD8α⁻ dn T cells also expressed substantial proportions of GATA-3. In addition, TCRαβ⁺CD4⁻CD8α⁻ dn T cells produced IFN-γ and IL-17A upon stimulation. T-bet and granzyme B were only weakly expressed by both dn T cell subsets. In conclusion, this study identifies two dn T cell subsets in the dog: (i) a large (~7.5% in Peyer's patches, ~15% in lung) population of TCRαβ⁺CD4⁻CD8α⁻ dn T cells with subpopulations thereof showing an activated phenotype, high expression of FoxP3 or GATA-3 as well as production of IFN-γ or IL-17A and (ii) a small TCRγδ⁺CD4⁻CD8α⁻ dn T cell subset also expressing GATA-3 without production of IFN-γ or IL-17A. It will be exciting to unravel the function of each subset during immune homeostasis and diseases of dogs.

Double negative T cells mediate Lag3-dependent antigen-specific protection in allergic asthma

Allergic asthma is an inflammatory disorder of the airway without satisfactory traditional therapies capable of controlling the underlying pathology. New approaches that can overcome the detrimental effects of immune dysregulation are thus desirable. Here we adoptively transfer ovalbumin (OVA) peptide-primed CD4⁻CD8⁻ double negative T (DNT) cells intravenously into a mouse model of OVA-induced allergic asthma to find that OVA-induced airway hyperresponsiveness, lung inflammation, mucus production and OVA-specific IgG/IgE production are significantly suppressed. The immunosuppressive function of the OVA-specific DNT cells is dependent on the inhibition of CD11b⁺ dendritic cell function, T follicular helper cell proliferation, and IL-21 production. Mechanistically, Lag3 contributes to MHC-II antigen recognition and trogocytosis, thereby modulating the antigen-specific immune regulation by DNT cells. The effectiveness of ex vivo-generated allergen-specific DNT cells in alleviating airway inflammation thus supports the potential utilization of DNT cell-based therapy for the treatment of allergic asthma.

Allergic asthma symptoms may be controlled, but currently no effective therapy exist to address the underlying pathology. Here the authors show, using mouse model of adoptive cell transfer, that CD4^-CD8^- T cells can suppress the function of dendritic cells and T follicular helper cells via Lag3 to provide allergen-specific protection from asthma.

Alteration of liver-infiltrated and peripheral blood double-negative T-cells in primary biliary cholangitis

BACKGROUND & AIMS

Double-negative (DN) T-cell is a unique regulatory T-cell, which is essential for maintaining immune system homoeostasis. However, the role of DN T-cells in the pathogenesis of primary biliary cholangitis (PBC) is still unknown.

METHODS

We investigated the number and function of DN T-cells in peripheral blood and liver biopsy specimens of PBC patients.

RESULTS

The number and frequency of DN T-cells significantly decreased in peripheral blood and liver tissue of PBC patients. Furthermore, the frequency of DN T-cells in PBC was negatively correlated with disease severity and positively correlated with ursodeoxycholic acid response. In vitro assays showed that perforin expression and the suppressive capability of DN T-cells on the proliferation of CD4⁺ and CD8⁺ T-cells were impaired in PBC. Finally, lithocholic acid, the most hydrophobic acid, could downregulate the proliferation and perforin expression of DN T-cells.

CONCLUSIONS

Decreased quantity and function of DN T-cells in PBC may result in the loss of immune regulations on effector CD4⁺ and cytotoxic CD8⁺ T-cells, and thereby may break the immune tolerance and promote the pathogenesis of PBC.

Human Double-Negative Regulatory T-Cells Induce a Metabolic and Functional Switch in Effector T-Cells by Suppressing mTOR Activity

The recently discovered population of TCRαβ+ CD4–/CD8– (double-negative, DN) T-cells are highly potent suppressor cells in mice and humans. In preclinical transplantation models, adoptive transfer of DN T-cells specifically inhibits alloreactive T-cells and prevents transplant rejection or graft-vs.-host disease (GvHD). Interestingly, clinical studies in patients who underwent allogeneic stem cell transplantation reveal an inverse correlation between the frequency of circulating DN T-cells and the severity of GvHD, suggesting a therapeutic potential of human DN T-cells. However, their exact mode of action has not been elucidated yet. Investigating the impact of DN T-cells on conventional T-cells, we found that human DN T-cells selectively inhibit mTOR signaling in CD4 T-cells. Given that mTOR is a critical regulator of cellular metabolism, we further determined the impact of DN T-cells on the metabolic framework of T-cells. Intriguingly, DN T-cells diminished expression of glucose transporters and glucose uptake, whereas fatty acid uptake was not modified, indicating that DN T-cells prevent metabolic adaptation of CD4 T-cells upon activation (i.e., glycolytic switch) thereby contributing to their suppression. Further analyses demonstrated that CD4 T-cells also do not upregulate homing receptors associated with inflammatory processes. In contrast, expression of central memory-cell associated cell surface markers and transcription factors were increased by DN T-cells. Moreover, CD4 T-cells failed to produce inflammatory cytokines after co-culture with DN T-cells, whereas IL-2 secretion was enhanced. Taken together DN T-cells impair metabolic reprogramming of conventional CD4 T-cells by abrogating mTOR signaling, thereby modulating CD4 T-cell functionality. These results uncover a new mechanism of DN T-cell-mediated suppression, pointing out that DN T-cells could serve as cell-based therapy to limit alloreactive immune response.

Human double negative T cells target lung cancer via ligand-dependent mechanisms that can be enhanced by IL-15

Background

The advents of novel immunotherapies have revolutionized the treatment of cancer. Adoptive cellular therapies using chimeric antigen receptor T (CAR-T) cells have achieved remarkable clinical responses in B cell leukemia and lymphoma but the effect on solid tumors including lung cancer is limited. Here we present data on the therapeutic potential of allogeneic CD3⁺CD4⁻CD8⁻ double negative T (DNT) cells as a new cellular therapy for the treatment of lung cancer and underlying mechanisms.

Methods

DNTs were enriched and expanded ex vivo from healthy donors and phenotyped by flow cytometry. Functionally, their cytotoxicity was determined against primary and established non-small-cell lung cancer (NSCLC) cell lines in vitro or through in vivo adoptive transfer into xenograft models. Mechanistic analysis was performed using blocking antibodies against various cell surface and soluble markers. Furthermore, the role of IL-15 on DNT function was determined.

Results

We demonstrated that ex vivo expanded DNTs can effectively lyse various human NSCLC cells in vitro and inhibit tumor growth in xenograft models. Expanded DNTs have a cytotoxic phenotype, as they express NKp30, NKG2D, DNAM-1, membrane TRAIL (mTRAIL), perforin and granzyme B, and secrete IFNγ and soluble TRAIL (sTRAIL). DNT-mediated cytotoxicity was dependent on a combination of tumor-expressed ligands for NKG2D, DNAM-1, NKp30 and/or receptors for TRAIL, which differ among different NSCLC cell lines. Furthermore, stimulation of DNTs with IL-15 increased expression of effector molecules on DNTs, their TRAIL production and cytotoxicity against NSCLC in vitro and in vivo.

Conclusion

Healthy donor-derived DNTs can target NSCLC in vitro and in vivo. DNTs recognize tumors via innate receptors which can be up-regulated by IL-15. DNTs have the potential to be used as a novel adoptive cell therapy for lung cancer either alone or in combination with IL-15.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0507-2) contains supplementary material, which is available to authorized users.

Immune Tolerance and Rejection in Organ Transplantation

In this chapter, we describe the history of transplantation, the multiple cell types, and mechanisms that are involved in rejection and tolerance of a transplanted organ, as well as summarize the common and promising new therapeutics used in transplant patients.

Infusion of ex-vivo expanded human TCR-αβ+ double-negative regulatory T cells delays onset of xenogeneic graft-versus-host disease

Despite the demonstration of potent immunosuppressive function of T cell receptor (TCR)-αβ⁺ double-negative regulatory T cells (DN T_regs ), scarce numbers and lack of effective expansion method limit their clinical applications. Here we describe an approach that allows for ∼3500-fold ex-vivo expansion of human DN T_regs within 3 weeks with > 97% purity. Ex-vivo-expanded DN T_regs suppress proliferation of polyclonally stimulated autologous T and B cells in vitro through direct cell-to-cell contact. In vivo, we demonstrate for the first time that infusion of human DN T_regs delayed an onset of xenogeneic graft-versus-host disease (GVHD) significantly in a humanized mouse model. Furthermore, preincubation of ex-vivo-expanded DN T_regs with a mechanistic target of rapamycin (mTOR) inhibitor rapamycin enhanced their immune regulatory function further. Taken together, this study demonstrates that human DN T_regs can be expanded ex vivo to therapeutic numbers. The expanded DN T_regs can suppress proliferation of T and B cells and attenuate GVHD, highlighting the potential clinical use of DN T_regs to mitigate GVHD.

Critical role of OX40 in the expansion and survival of CD4 T-cell-derived double-negative T cells

CD4⁺ T-cell-converted CD4⁻CD8⁻ double negative (cDNT) have strong suppressive activity in the maintenance of immune tolerance, whereas IL-2 promotes cDNT proliferation and enhances cDNT resistance to apoptosis. However, the intrinsic mechanisms that regulate the survival of cDNT are still unknown. Here we demonstrate that the OX40 molecule was highly expressed on cDNT. The expression of OX40 was necessary to promote proliferation and inhibit apoptosis of cDNT in vivo and in vitro. OX40 promoted the survival of cDNT by regulating the expression of Bcl-2, Bcl-xL, Survivin, and BCL2L11. Canonical NF-κB cell signaling played an important role in the transmission of essential division and survival signals through OX40 in cDNT. IL-2 promoted the survival of cDNT in part via elevating the expression of the OX40 molecule. IL-2 promoted OX40 expression via downregulating the PPARα expression. In conclusion, we elucidated that OX40 is a key molecule that regulates cDNT proliferation and survival. IL-2 promoted OX40 expression by downregulating the PPARα binding to the OX40 promoter, leading to the elevated expression of Bcl-2, Bcl-xL, and Survivin in cDNT, which finally resulted in the promoted proliferation and decreased apoptosis of cDNT.

Genetic interaction between two insulin-dependent diabetes susceptibility loci, Idd2 and Idd13, in determining immunoregulatory DN T cell proportion

Several immune regulatory cell types participate in the protection against autoimmune diseases such as autoimmune diabetes. Of these immunoregulatory cells, we and others have shown that peripheral CD4^-CD8^- double negative (DN) T cells can induce antigen-specific immune tolerance. Particularly, we have described that diabetes-prone mice exhibit a lower number of peripheral DN T cells compared to diabetes-resistant mice. Identifying the molecular pathways that influence the size of the DN T cell pool in peripheral lymphoid organs may thus be of interest for maintaining antigen-specific immune tolerance. Hence, through immunogenetic approaches, we found that two genetic loci linked to autoimmune diabetes susceptibility, namely Idd2 and Idd13, independently contribute to the partial restoration of DN T cell proportion in secondary lymphoid organs. We now extend these findings to show an interaction between the Idd2 and Idd13 loci in determining the number of DN T cells in secondary lymphoid organs. Using bioinformatics tools, we link potential biological pathways arising from interactions of genes encoded within the two loci. By focusing on cell cycle, we validate that both the Idd2 and Idd13 loci influence RAD51 expression as well as DN T cell progression through the cell cycle. Altogether, we find that genetic interactions between Idd2 and Idd13 loci modulate cell cycle progression, which contributes, at least in part, to defining the proportion of DN T cells in secondary lymphoid organs.

Targeting chemotherapy-resistant leukemia by combining DNT cellular therapy with conventional chemotherapy

Background

While conventional chemotherapy is effective at eliminating the bulk of leukemic cells, chemotherapy resistance in acute myeloid leukemia (AML) is a prevalent problem that hinders conventional therapies and contributes to disease relapse, and ultimately patient death. We have recently shown that allogeneic double negative T cells (DNTs) are able to target the majority of primary AML blasts in vitro and in patient-derived xenograft models. However, some primary AML blast samples are resistant to DNT cell therapy. Given the differences in the modes of action of DNTs and chemotherapy, we hypothesize that DNT therapy can be used in combination with conventional chemotherapy to further improve their anti-leukemic effects and to target chemotherapy-resistant disease.

Methods

Drug titration assays and flow-based cytotoxicity assays using ex vivo expanded allogeneic DNTs were performed on multiple AML cell lines to identify therapy-resistance. Primary AML samples were also tested to validate our in vitro findings. Further, a xenograft model was employed to demonstrate the feasibility of combining conventional chemotherapy and adoptive DNT therapy to target therapy-resistant AML. Lastly, blocking assays with neutralizing antibodies were employed to determine the mechanism by which chemotherapy increases the susceptibility of AML to DNT-mediated cytotoxicity.

Results

Here, we demonstrate that KG1a, a stem-like AML cell line that is resistant to DNTs and chemotherapy, and chemotherapy-resistant primary AML samples both became more susceptible to DNT-mediated cytotoxicity in vitro following pre-treatment with daunorubicin. Moreover, chemotherapy treatment followed by adoptive DNT cell therapy significantly decreased bone marrow engraftment of KG1a in a xenograft model. Mechanistically, daunorubicin increased the expression of NKG2D and DNAM-1 ligands on KG1a; blocking of these pathways attenuated DNT-mediated cytotoxicity.

Conclusions

Our results demonstrate the feasibility and benefit of using DNTs as an immunotherapy after the administration of conventional chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0756-9) contains supplementary material, which is available to authorized users.

TCRαβ+CD3+CD4-CD8- (double negative) T cells in autoimmunity

TCRαβ⁺CD3⁺CD4^-CD8^- "double negative" (DN) T cells comprise a small subset of mature peripheral T cells. The origin and function of DN T cells are somewhat unclear and discussed controversially. While DN T cells resemble a rare and heterogeneous T cell subpopulation in healthy individuals, numbers of TCRαβ⁺ DN T cells are expanded in several inflammatory conditions, where they also exhibit distinct effector phenotypes and infiltrate inflamed tissues. Thus, DN T cells may be involved in systemic inflammation and tissue damage in autoimmune/inflammatory conditions, including SLE, Sjögren's syndrome, and psoriasis. Here, the current understanding of the origin and phenotype of DN T cells, and their role in the instruction of immune responses, autoimmunity and inflammation will be discussed in health and disease.

Current Status of Gene Engineering Cell Therapeutics

Ex vivo manipulations of autologous patient’s cells or gene-engineered cell therapeutics have allowed the development of cell and gene therapy approaches to treat otherwise incurable diseases. These modalities of personalized medicine have already shown great promises including product commercialization for some rare diseases. The transfer of a chimeric antigen receptor or T cell receptor genes into autologous T cells has led to very promising outcomes for some cancers, and particularly for hematological malignancies. In addition, gene-engineered cell therapeutics are also being explored to induce tolerance and regulate inflammation. Here, we review the latest gene-engineered cell therapeutic approaches being currently explored to induce an efficient immune response against cancer cells or viruses by engineering T cells, natural killer cells, gamma delta T cells, or cytokine-induced killer cells and to modulate inflammation using regulatory T cells.

Microbiota promotes systemic T-cell survival through suppression of an apoptotic factor

Symbiotic microbes impact the severity of a variety of diseases through regulation of T-cell development. However, little is known regarding the molecular mechanisms by which this is accomplished. Here we report that a secreted factor, Erdr1, is regulated by the microbiota to control T-cell apoptosis. Erdr1 expression was identified by transcriptome analysis to be elevated in splenic T cells from germfree and antibiotic-treated mice. Suppression of Erdr1 depends on detection of circulating microbial products by Toll-like receptors on T cells, and this regulation is conserved in human T cells. Erdr1 was found to function as an autocrine factor to induce apoptosis through caspase 3. Consistent with elevated levels of Erdr1, germfree mice have increased splenic T-cell apoptosis. RNA sequencing of Erdr1-overexpressing cells identified the up-regulation of genes involved in Fas-mediated cell death, and Erdr1 fails to induce apoptosis in Fas-deficient cells. Importantly, forced changes in Erdr1 expression levels dictate the survival of auto-reactive T cells and the clinical outcome of neuro-inflammatory autoimmune disease. Cellular survival is a fundamental feature regulating appropriate immune responses. We have identified a mechanism whereby the host integrates signals from the microbiota to control T-cell apoptosis, making regulation of Erdr1 a potential therapeutic target for autoimmune disease.

Low Double-Negative CD3+CD4-CD8- T Cells Are Associated with Incomplete Restoration of CD4+ T Cells and Higher Immune Activation in HIV-1 Immunological Non-Responders

Failure of immune reconstitution increases the risk of AIDS or non-AIDS related morbidity and mortality in HIV-1-infected patients. CD3⁺CD4⁻CD8⁻ T cells, which are usually described as double-negative (DN) T cells, display CD4-like helper and immunoregulatory functions. Here, we have measured the percentage of DN T cells in the immune reconstituted vs. non-immune reconstituted HIV-1-infected individuals. We observed that immunological non-responders (INRs) had a low number of DN T cells after long-term antiretroviral therapy (ART), and the number of these cells positively correlated with the CD4⁺ T cell count. The ART did not result in complete suppression of immune activation recorded by the percentage of CD38⁺HLA-DR⁺CD8⁺ T cells in INRs, and a strong inverse correlation was observed between DN T cells and immune activation. A low proportion of TGF-β1⁺DN T cells was found in INRs. Further mechanism study demonstrated that the level of TGF-β1-producing DN T cells and immune activation had a negative correlation after ART. Taken together, our study suggests that DN T cells control the immunological response in HIV-1-infected patients. These findings expand our understanding of the mechanism of immune reconstitution and could develop specific treatments to return the immune system to homeostasis following initiation of HIV-1 therapy.

Potential role of IL-17-producing CD4/CD8 double negative αβ T cells in psoriatic skin inflammation in a TPA-induced STAT3C transgenic mouse model

BACKGROUND

Psoriasis is one of the most common immune-mediated chronic inflammatory skin disorders and is accompanied by erythematous scaly plaques. There is growing evidence that the IL-23/Th17 axis plays a critical role in development of the disease. It was recently shown that in addition to CD4⁺ Th17 cells, various IL-17-producing cell subsets such as CD8⁺ Tc17 cells, dermal γδ T cells, and innate lymphoid cells are also involved in the development of psoriatic inflammation in humans.

OBJECTIVE

To investigate which subsets of IL-17-producing cells are involved in psoriasis-like skin inflammation in a TPA (tumor promoter 12-O-tetradecanoylphorbol-13-acetate)-induced K14.Stat3C mouse model.

METHOD

Skin-infiltrating cells were isolated from inflamed lesions of TPA-treated K14.Stat3C transgenic mice, and analyzed for IL-17 producing cell subsets by flow cytometry.

RESULTS

We observed significantly increased numbers of IL-17-producing CD4⁺ T cells, CD8⁺ T cells and dermal γδ T cells in TPA-induced skin lesions of K14.Stat3C mice. Additionally, we found that another IL-17-producing T cell subset, αβ-TCR⁺ CD4CD8 double negative T cells (DN αβ T cells), was also increased in lesional skin. These IL-17-producing DN αβ T cells are NK1.1 negative, suggesting they are not natural killer T cells or mucosal associated invariant T cells. As well as other IL-17-producing cells, DN αβ T cells in the inflamed skin can also respond to IL-23 stimulation to produce IL-17. It is also suggested that DN αβ T cells may express retinoic acid-related orphan receptor gamma t and CC chemokine receptor 6.

CONCLUSION

In TPA-induced lesional skin of K14.Stat3C mice, IL-17-producing CD4⁺ Th17 cells, CD8⁺ Tc17 cells, dermal γδ T cells and TCR^- cells probably containing ILCs all participated in skin inflammation, which is similar to human clinical psoriatic features. Furthermore, we showed for the first time the possibility that an IL-17-producing DN αβ T cell subset is also involved in psoriatic inflammation.

Heat shock proteins and their immunomodulatory role in inflammatory arthritis

Autoimmune diseases, including inflammatory arthritis, are characterized by a loss of self-tolerance, leading to an excessive immune responses and subsequent ongoing inflammation. Current therapies are focused on dampening this inflammation, but a permanent state of tolerance is seldom achieved. Therefore, novel therapies that restore and maintain tolerance are needed. Tregs could be a potential target to achieve permanent immunotolerance. Activation of Tregs can be accomplished when they recognize and bind their specific antigens. HSPs are proteins present in all cells and are upregulated during inflammation. These proteins are immunogenic and can be recognized by Tregs. Several studies in animal models and in human clinical trials have shown the immunoregulatory effects of HSPs and their protective effects in inflammatory arthritis. In this review, an overview is presented of the immunomodulatory effects of several members of the HSP family in general and in inflammatory arthritis. These effects can be attributed to the activation of Tregs through cellular interactions within the immune system. The effect of HSP-specific therapies in patients with inflammatory arthritis should be explored further, especially with regard to long-term efficacy and safety and their use in combination with current therapeutic approaches.

Double-negative T resident memory cells of the lung react to influenza virus infection via CD11c(hi) dendritic cells

Immunity to Influenza A virus (IAV) is controlled by conventional TCRαβ(+) CD4(+) and CD8(+) T lymphocytes, which mediate protection or cause immunopathology. Here, we addressed the kinetics, differentiation, and antigen specificity of CD4(-)CD8(-) double-negative (DN) T cells. DNT cells expressed intermediate levels of TCR/CD3 and could be further divided in γδ T cells, CD1d-reactive type I NKT cells, NK1.1(+) NKT-like cells, and NK1.1(-) DNT cells. NK1.1(-) DNT cells had a separate antigen-specific repertoire in the steady-state lung, and expanded rapidly in response to IAV infection, irrespectively of the severity of infection. Up to 10% of DNT cells reacted to viral nucleoprotein. Reinfection experiments with heterosubtypic IAV revealed that viral replication was a major trigger for recruitment. Unlike conventional T cells, the NK1.1(-) DNT cells were in a preactivated state, expressing memory markers CD44, CD11a, CD103, and the cytotoxic effector molecule FasL. DNT cells resided in the lung parenchyma, protected from intravascular labeling with CD45 antibody. The recruitment and maintenance of CCR2(+) CCR5(+) CXCR3(+) NK1.1(-) DNT cells depended on CD11c(hi) dendritic cells (DCs). Functionally, DNT cells controlled the lung DC subset balance, suggesting they might act as immunoregulatory cells. In conclusion, we identify activation of resident memory NK1.1(-) DNT cells as an integral component of the mucosal immune response to IAV infection.

Hyperactive mTOR pathway promotes lymphoproliferation and abnormal differentiation in autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder characterized by defective Fas signaling, resulting in chronic benign lymphoproliferation and accumulation of TCRαβ(+) CD4(-) CD8(-) double-negative T (DNT) cells. Although their phenotype resembles that of terminally differentiated or exhausted T cells, lack of KLRG1, high eomesodermin, and marginal T-bet expression point instead to a long-lived memory state with potent proliferative capacity. Here we show that despite their terminally differentiated phenotype, human ALPS DNT cells exhibit substantial mitotic activity in vivo. Notably, hyperproliferation of ALPS DNT cells is associated with increased basal and activation-induced phosphorylation of serine-threonine kinases Akt and mechanistic target of rapamycin (mTOR). The mTOR inhibitor rapamycin abrogated survival and proliferation of ALPS DNT cells, but not of CD4(+) or CD8(+) T cells in vitro. In vivo, mTOR inhibition reduced proliferation and abnormal differentiation by DNT cells. Importantly, increased mitotic activity and hyperactive mTOR signaling was also observed in recently defined CD4(+) or CD8(+) precursor DNT cells, and mTOR inhibition specifically reduced these cells in vivo, indicating abnormal programming of Fas-deficient T cells before the DNT stage. Thus, our results identify the mTOR pathway as a major regulator of lymphoproliferation and aberrant differentiation in ALPS.

CXCR5 is critically involved in progression of lupus through regulation of B cell and double-negative T cell trafficking

The recruitment of immune cells to sites of tissue inflammation is orchestrated by chemokine/chemokine receptor networks. Among these, the CXCL13/CXCR5 axis is thought to be involved critically in systemic lupus erythematosus (SLE) and lupus nephritis pathogenesis. Beyond B cell abnormalities, another hallmark of SLE disease is the occurrence of aberrant T cell responses. In particular, double-negative (DN) T cells are expanded in the peripheral blood of patients with SLE and in lupus-prone mice. DN T cells induce immunoglobulin production, secrete proinflammatory cytokines and infiltrate inflamed tissue, including kidneys. We aimed to investigate how CXCR5 deficiency changes immune cell trafficking in murine lupus. We therefore crossed CXCR5(-/-) mice with B6/lpr mice, a well-established murine lupus model. B cell numbers and B cellular immune responses were diminished in CXCR5-deficient B6/lpr mice. In addition, we observed reduced accumulation of DN T cells in spleen and lymph nodes, paralleled by reduced splenomegaly and lymphadenopathy. In-vivo migration assays revealed reduced migration of CXCR5-deficient DN T cells into lymph nodes, and ex-vivo-activated CXCR5-deficient DN T cells failed to infiltrate kidneys of recipients. Moreover, DN T cells and B cells of CXCR5-deficient B6/lpr mice failed to migrate towards CXCL13 in vitro. We propose that CXCR5 is involved critically in B cell trafficking and germinal cell (GC) formation in murine lupus and in guiding pathogenic DN T cells into lymphoid organs and kidneys, and we therefore describe new pathomechanisms for the CXCL13/CXCR5 axis in SLE.

A disparate subset of double-negative T cells contributes to the outcome of murine fulminant viral hepatitis via effector molecule fibrinogen-like protein 2

The underlying immune-mediated mechanisms involved in virus-induced severe hepatitis have not been well elucidated. In this study, we investigated the role of CD3(+)CD4(-)CD8(-) double-negative T (DN T) cells in the pathogenesis of fulminant viral hepatitis (FVH) induced by murine hepatitis virus strain 3 (MHV-3). After MHV-3 infection, the proportions of DN T cells increased significantly in BALB/cJ mice, and splenic DN T cells expressing high levels of CD69 were recruited by MHV-3-infected hepatocytes to the liver. Serum levels of alanine aminotransferase, aspartate aminotransferase and total bilirubin increased, accompanied by massive hepatocyte necrosis. These DN T cells were predominantly consisted of a TCRαβ(+) subset expressing high levels of CD44 and did not produce cytokine except IL-2. Adoptive transfer of this subset of DN T cells to the MHV-3-infected mice resulted in an increase in murine fibrinogen-like protein 2 (mfgl2) expressions in association with massive fibrin deposition in the liver. Following MHV-3 infection, membrane mfgl2 expression and functional procoagulant activity increased remarkably in the DN T cells. Introduction of a recombinant adenovirus which encoded a microRNA specifically targeting mfgl2 gene (Ad-mfgl2-miRNA) in vivo significantly inhibited the hepatic expression of mfgl2 and improved survival in mice. However, under this condition, adoptive transfer of the DN T cells accelerated the disease progression and reversed the benefit from mfgl2 gene silence, leading to a 100 % death rate. Our results demonstrate that DN T cells contribute to the outcome of MHV-3-induced FVH via an important effector molecule mfgl2.

DNT cell inhibits the growth of pancreatic carcinoma via abnormal expressions of NKG2D and MICA in vivo

This research aimed to investigate the effects of natural killer group 2 member D (NKG2D) and its ligands major histocompatibility complex class I chain-related molecules A(MICA) in DNT cell killing pancreatic carcinoma. Antibodies adsorption was used to separate DNT cell from human peripheral blood. Human pancreatic tumor models were established via implanting BXPC-3 cells into nude mice. Then randomly divided mice into blank group, gemcitabine group and DNT group. Mice weights and mice tumor volumes were measured every 5 days. 50 days later mice were euthanized at cervical dislocation method. Tumor weights were measured. Relative tumor volume and tumor inhibition rate were calculated. Western blot and qPCR were used to detect the expressions of NKG2D and MICA in the transplanted tumors of the three groups. DNT cell significantly increased over time. The blank group tumor volume and weight were significantly larger than the other groups (p < 0.001, p < 0.001), but there were no significantly difference between DNT group and gemcitabine group (p > 0.05). Gemcitabine and DNT cell tumor inhibition rate were 40.4% and 35.5%. Western blot and qPCR showed that MICA mRNA and protein levels in blank group were significantly higher than DNT group (p = 0.001, p = 0.003). NKG2D mRNA and protein levels in blank group were significantly lower than DNT cells group (p < 0.001, p = 0.001). In conclusion DNT cell can significantly inhibit the growth of pancreatic carcinoma in vivo, and the mechanism may be involved in abnormal expressions of MICA and NKG2D.

Advances on Non-CD4 + Foxp3+ T Regulatory Cells: CD8+, Type 1, and Double Negative T Regulatory Cells in Organ Transplantation

The overwhelming body of research on T regulatory cells (Treg) has focused on CD4 + CD25 + Foxp3+ T cells. However, recent years have witnessed a resurgence in interest in CD4 - CD8+, CD4 - CD8- (double negative [DN]), and CD4 + Foxp3- type 1 Treg (Tr1) Treg and their role in controlling autoimmune diseases and in promoting the survival of organ allografts and xenografts. CD8+ and DN Treg can arise spontaneously (natural Treg) or can be induced in situ. Both CD8+ and DN Treg have been shown to enhance the survival of organ allografts and xenografts. Additionally, both can suppress alloimmune responses by contact-dependent mechanisms by either inducing apoptosis or mediating direct cytolysis of effector T cells. CD8+, DN, and Tr1 Treg can also act in a contact-independent manner by elaborating soluble immunosuppressive factors, such as TGF-β and IL-10. Applying CD8+, DN, and Tr1 Treg for enhancing the survival of organ allografts and xenografts is still in its infancy but holds significant potential. Furthermore, there is a need for a more comprehensive understanding of how current immunosuppressive therapies applied to organ transplantations affect the wide array of Treg populations.

Double-Negative αβ T Cells Are Early Responders to AKI and Are Found in Human Kidney

Ischemia-reperfusion injury (IRI) is a major cause of AKI, and previous studies established important roles for conventional CD4(+) T cells, natural killer T cells, and CD4(+)CD25(+)FoxP3(+) Tregs in AKI pathogenesis. We recently identified CD4(-)CD8(-) (double-negative; DN) T cells as an important subset of αβ T cell receptor-positive cells residing in mouse kidney. However, little is known about the pathophysiologic functions of kidney DN T cells. In this study, we phenotypically and functionally characterized murine kidney DN T cells in the steady state and in response to IRI. Unlike CD4(+) and CD8(+) T cells, DN T cells in the steady state expressed high levels of CD69, CD28, and CD40L; differentially expressed IL-27 and IL-10 anti-inflammatory cytokines; spontaneously proliferated at a very high rate; and suppressed in vitro proliferation of activated CD4(+) T cells. Within the first 3-24 hours after IRI, kidney DN T cells expanded significantly and upregulated expression of IL-10. In adoptive transfer experiments, DN T cells significantly protected recipients from AKI by an IL-10-dependent mechanism. DN T cells also made up a large fraction of the T cell compartment in human kidneys. Our results indicate that DN T cells are an important subset of the resident αβ(+) T cell population in the mammalian kidney and are early responders to AKI that have anti-inflammatory properties.

Challenges and future perspectives of T cell immunotherapy in cancer

Since the formulation of the tumour immunosurveillance theory, considerable focus has been on enhancing the effectiveness of host antitumour immunity, particularly with respect to T cells. A cancer evades or alters the host immune response by various ways to ensure its development and survival. These include modifications of the immune cell metabolism and T cell signalling. An inhibitory cytokine milieu in the tumour microenvironment also leads to immune suppression and tumour progression within a host. This review traces the development in the field and attempts to summarize the hurdles that the approach of adoptive T cell immunotherapy against cancer faces, and discusses the conditions that must be improved to allow effective eradication of cancer.

Pathological conditions re-shape physiological Tregs into pathological Tregs

CD4⁺FOXP3⁺ regulatory T cells (Tregs) are a subset of CD4 T cells that play an essential role in maintaining peripheral immune tolerance, controlling acute and chronic inflammation, allergy, autoimmune diseases, and anti-cancer immune responses. Over the past 20 years, significant progress has been made since Tregs were first characterized in 1995. Many concepts and principles regarding Tregs generation, phenotypic features, subsets (tTregs, pTregs, iTregs, and iTreg35), tissue specificity (central Tregs, effector Tregs, and tissue resident Tregs), homeostasis (highly dynamic and apoptotic), regulation of Tregs by receptors for PAMPs and DAMPs, Treg plasticity (re-differentiation to other CD4 T helper cell subsets, Th1, Th2, Tfh and Th17), and epigenetic regulation of Tregs phenotypes and functions have been innovated. In this concise review, we want to briefly analyze these eight new progresses in the study of Tregs. We have also proposed for the first time a novel concept that "physiological Tregs" have been re-shaped into "pathological Tregs" in various pathological environments. Continuing of the improvement in our understanding on this important cellular component about the immune tolerance and immune suppression, would lead to the future development of novel therapeutics approaches for acute and chronic inflammatory diseases, allergy, allogeneic transplantation-related immunity, sepsis, autoimmune diseases, and cancers.

TCR+CD4-CD8- T cells in antigen-specific MHC class I-restricted T-cell responses after allogeneic hematopoietic stem cell transplantation

Human TCRαβ(+) CD4(-)CD8(-) double-negative (DN) T cells represent a minor subset in peripheral blood, yet are important in infectious diseases and autoimmune responses. We examined the frequency of DN T cells in 17 patients after allogeneic hematopoietic stem cell transplantation (aHSCT) at 1, 2, 3, 6, and 12 months post-aHSCT and show that these cells increase early after aHSCT and decrease with time after aHSCT. DN T cells reside in the terminally differentiated effector (CD45RA(+)CCR7(-)) T-cell population and are polyclonal, determined by T-cell receptor Vβ CDR3 analysis. Gene expression analysis of ex vivo sorted DN T cells showed a distinct set of gene expression, including interleukin-8, as compared with CD4(+) or CD8(+) T cells. DN T cells contributed to MHC class I-restricted EBV-directed immune responses, defined by antigen-specific cytokine production and by detection of HLA-A*02:01-restricted EBV BMLF-1 (GLCTLVAML), LMP-2A (CLGGLLTMV), and HLA-A*24:02-restricted EBV BRLF-1 (DYCNVLNKEF) and EBNA3 (RYSIFFDY)-specific T cells. We created retroviral-transfected Jurkat cell lines with a Melan-A/MART-1-specific TCR(+) and the CD8α chain to study TCR(+) DN T cells in response to their nominal MHC class I/peptide ligand. We show that DN T cells exhibit increased TCRζ chain phosphorylation as compared with the TCR(+)CD8(+) transgenic T-cell line. DN T cells contribute to antigen-specific T-cell responses and represent an effector T-cell population that may be explored in immunotherapeutic approaches against viral infections or transformed cells.

Programmed cell death 1 and Helios distinguish TCR-αβ+ double-negative (CD4-CD8-) T cells that derive from self-reactive CD8 T cells

TCR-αβ(+) double-negative (DN; CD4(-)CD8(-)) T cells represent a poorly understood cellular subset suggested to contribute to the pathogenesis of the autoimmune disease systemic lupus erythematosus. DN T cells have been proposed to derive from CD8(+) cells. However, the conditions that govern the loss of CD8 expression after Ag encounter are unknown. In this study, we tracked the fate of CD8 T cells from transgenic TCR mice exposed to their cognate Ags as self or in the context of infection. We demonstrate that CD8 T cells lose CD8 expression and become DN only when cognate Ag is sensed as self. This process is restricted to tissues where the Ag is present. We also show that DN T cells derived from self-reactive CD8 cells express the inhibitory molecules PD-1 and Helios. These molecules identify a subset of DN T cells in normal mice. A similar population expands when CD8 T cells from repertoires enriched in self-reactive cells (Aire-deficient) are transferred into cognate hosts. Collectively, our data suggest that a subset of DN T cells, identified by the expression of PD-1 and Helios, represent self-reactive cells. Our results provide an explanation for the origin of DN T cells and introduce CD8 loss as a process associated with self-Ag encounter.

The DNA methylation signature of human TCRαβ+CD4-CD8- double negative T cells reveals CG demethylation and a unique epigenetic architecture permissive to a broad stimulatory immune response

T cell receptor (TCR) αβ+CD4-CD8- double negative T cells represent a rare T cell subset implicated in the pathogenesis of several autoimmune diseases. We investigated the DNA methylation signature of double negative T cells to gain insight into the epigenetic architecture of peripheral blood primary human double negative T cells compared to autologous CD4+ and CD8+ T cells. We identified 2984 CG sites across the genome with unique loss of DNA methylation in double negative T cells, and showed significant reduction in mRNA expression of DNA methyltransferases DNMT1, DNMT3A, and DNMT3B. DNA methylation was increased in CD8A/CD8B and CD4 consistent with epigenetic repression of both the CD8 and CD4 genetic loci in double negative T cells. We show a consistent increase in non-CG methylation in double negative T cells, a finding suggestive of pluripotency. Network analyses indicate a strong relationship between double negative T cells and functions related to cell-cell interaction, cell adhesion, and cell activation pathways. Our data also suggest a robust pro-inflammatory epigenetic signature in double negative T cells, consistent with a transcriptional permissiveness in key inflammatory cytokines including IFNγ, IL-17F, IL-12B, IL-5, IL-18, TNFSF11 (RANKL), and TNFSF13B (BLYS or BAFF). These findings highlight an epigenetic basis for a role of double negative T cells in autoimmunity.

CD30 ligand is a new therapeutic target for central nervous system autoimmunity

The CD30 ligand (CD30L)/CD30 axis plays a critical role in Th1 and Th17 cell differentiation. However, the role in the pathogenesis of central nervous system autoimmunity remains unknown. Here we show the resistance for experimental autoimmune encephalomyelitis (EAE) with markedly reduced induction of antigen-specific Th1 and Th17 cells in CD30L knockout mice. Bone marrow chimera experiments indicated that CD30L on bone marrow-derived cells were critical for the development of EAE and that CD30L reverse signaling in CD4 T cells was dispensable for the pathogenic Th17 cell differentiation at the induction phase. Adoptive transfer experiment revealed an additional role for CD30L in the environment at the effector phase. In vivo neutralization of CD30L by soluble murine CD30-Immunoglobulin fusion protein before disease onset or even after disease onset significantly ameliorated the clinical symptoms. These results indicate that CD30L/CD30 signaling is critically involved in antigen-specific CD4 T cell responses at both the induction and effector phase, thus could be a new target molecule for the treatment of central nervous system autoimmunity.

Immune cell therapy in IBD

The therapeutic landscape of IBD has undergone a dramatic transformation since the advent of biologic therapies, especially TNF inhibitors. However, 30% of patients are primary nonresponders to biologic therapy and secondary failures are frequent. Due to substantial progress in our understanding of the biology of regulatory T cells (Tregs) and in the pathways of homing to the gastrointestinal tract, novel cell-based therapies for IBD have become possible. For example, although a reductionist view, one could envisage IBD as an imbalance between the proinflammatory effectors (such as Th17 cells) and the anti-inflammatory regulators (like Tregs). Here we focus on the development of ex vivo and in vivo approaches to enhance Tregs in the gastrointestinal tract. Specifically, herein we highlight a recently concluded phase 1/2a clinical trial that investigated the safety and efficacy of a single injection of escalating doses of autologous ovalbumin-specific Tregs in patients with active Crohn's disease refractory to conventional therapy. This therapy was well tolerated and demonstrated dose-related efficacy. We also discuss the potential of directing Tregs derived through intranasal as well as epicutaneous immunization to the gastrointestinal tract by enhancing their gut homing signature and their potential to decrease gastrointestinal inflammation. Finally, the strengths and pitfalls of these new therapeutic approaches are discussed as we move forward in this largely uncharted territory.

Discovery of prognostic factors for diagnosis and treatment of epithelial-derived ovarian cancer from laying hens

Ovarian cancer is a lethal gynecological cancer causing cancer-related deaths in women worldwide. It is difficult to diagnosis at an early stage when more than 90% patients can be cured because of lack of specific symptoms and early detection markers. Most of malignant ovarian tumors are originated from the germinal epithelium of the ovary. For investigation with animal models of epithelial-derived ovarian cancer (EOC), laying hens are the most relevant animal models because they spontaneously develop EOC as occurs in women through ovulating almost every day. As in women, EOC in the hen is age-related and grossly and histologically similar to that in women. However, domesticated animals are inappropriate for research human EOC due to multiple pregnancies and lactating or seasonally anestrous. In addition, the non-spontaneous nature of rodents EOC limits clinical relevance with human EOC. Recent studies have shown that ovarian cancer could arise from epithelium from the oviduct as oviduct-related genes are up-regulated in EOC of hens. Therefore, we showed in the review: 1) characterization and classification of EOC; 2) chicken models for EOC; 3) relationship estrogen with EOC; 4) candidate prognostic factors for EOC including serpin peptidase inhibior, clade B (ovalbumin), member 3 (SERPINB3), SERPINB11, gallicin 11 (GAL11), secreted phosphoprotein 1 (SPP1) and alpha 2 macroglobulin (A2M) in normal and cancerous ovaries of laying hens; 5) biological roles of microRNAs in development of EOC. Collectively, the present reviews indicate that expression of SERPINB3, SERPINB11, GAL11, SPP1 and A2M is clearly associated with the development of ovarian carcinogenesis. These results provide new insights into the prognostic biomarkers for EOC to diagnose and to evaluate responses to therapies for treating EOC of humans.

MHC class II restricted innate-like double negative T cells contribute to optimal primary and secondary immunity to Leishmania major

Although it is generally believed that CD4⁺ T cells play important roles in anti-Leishmania immunity, some studies suggest that they may be dispensable, and that MHC II-restricted CD3⁺CD4⁻CD8⁻ (double negative, DN) T cells may be more important in regulating primary anti-Leishmania immunity. In addition, while there are reports of increased numbers of DN T cells in Leishmania-infected patients, dogs and mice, concrete evidence implicating these cells in secondary anti-Leishmania immunity has not yet been documented. Here, we report that DN T cells extensively proliferate and produce effector cytokines (IFN-γ, TNF and IL-17) and granzyme B (GrzB) in the draining lymph nodes and spleens of mice following primary and secondary L. major infections. DN T cells from healed mice display functional characteristics of protective anti-Leishmania memory-like cells: rapid and extensive proliferation and effector cytokines production following L. major challenge in vitro and in vivo. DN T cells express predominantly (> 95%) alpha-beta T cell receptor (αβ TCR), are Leishmania-specific, restricted mostly by MHC class II molecules and display transcriptional profile of innate-like genes. Using in vivo depletion and adoptive transfer studies, we show that DN T cells contribute to optimal primary and secondary anti-Leishmania immunity in mice. These results directly identify DN T cells as important players in effective and protective primary and secondary anti-L. major immunity in experimental cutaneous leishmaniasis.

Although it is generally believed that CD4⁺ T cells mediate anti-Leishmania immunity, some studies suggest that CD3⁺CD4⁻CD8⁻ (double negative, DN) T cells may play a more important role in regulating primary anti-Leishmania immunity. Here, we report that DN T cells extensively proliferate and produce effector cytokines in mice following primary and secondary L. major infections. Leishmania-reactive DN T cells utilize αβ T cell receptor (TCR) and are restricted by MHC class II molecules. Strikingly, DN T cells from healed mice display functional characteristics of protective anti-Leishmania memory-like cells: rapid and extensive proliferation, effector cytokine production in vitro and in vivo, and accelerated parasite control following secondary L. major challenge. These results directly identify DN T cells as important players in protective primary and secondary anti-L. major immunity in experimental cutaneous leishmaniasis.

The mouse idd2 locus is linked to the proportion of immunoregulatory double-negative T cells, a trait associated with autoimmune diabetes resistance

Autoimmune diseases result from a break in immune tolerance. Various mechanisms of peripheral tolerance can protect against autoimmunity, including immunoregulatory CD4(-)CD8(-) double-negative (DN) T cells. Indeed, we have previously shown that diabetes-prone mouse strains exhibit a low proportion of DN T cells relative to that of diabetes-resistant mice, and that a single autologous transfer of DN T cells can impede autoimmune diabetes development, at least in the 3A9 TCR transgenic setting. In this study, we aim to understand the genetic basis for the difference in DN T cell proportion between diabetes-resistant and diabetes-prone mice. We thus perform an unbiased linkage analysis in 3A9 TCR F2 (NOD.H2(k) × B10.BR) mice and reveal that a locus on chromosome 9, which coincides with Idd2, is linked to the proportion of DN T cells in the lymph nodes. We generate two NOD.H2(k).B10-Chr9 congenic mouse strains and validate the role of this genetic interval in defining the proportion of DN T cells. Moreover, we find that the increased proportion of DN T cells in lymphoid organs is associated with a decrease in both diabetes incidence and serum IgG Ab levels. Together, the data suggest that Idd2 is linked to DN T cell proportion and that a physiological increase in DN T cell number may be sufficient to confer resistance to autoimmune diabetes. Altogether, these findings could help identify new candidate genes for the development of therapeutic avenues aimed at modulating DN T cell number for the prevention of autoimmune diseases.

The clinical correlation of regulatory T cells and cyclic adenosine monophosphate in enterovirus 71 infection

Background

Brainstem encephalitis (BE) and pulmonary edema (PE) are notable complications of enterovirus 71 (EV71) infection.

Objective

This study investigated the immunoregulatory characterizations of EV71 neurological complications by disease severity and milrinone treatment.

Study Design

Patients <18 years with virologically confirmed EV71 infections were enrolled and divided into 2 groups: the hand, foot, and mouth disease (HFMD) or BE group, and the autonomic nervous system (ANS) dysregulation or PE group. Cytokine and cyclic adenosine monophosphate (cAMP) levels, and the regulatory T cell (Tregs) profiles of the patients were determined.

Results

Patients with ANS dysregulation or PE exhibited significantly low frequency of CD4⁺CD25⁺Foxp3⁺ and CD4⁺Foxp3⁺ T cells compared with patients with HFMD or BE. The expression frequency of CD4⁻CD8⁻ was also significantly decreased in patients with ANS dysregulation or PE. Among patients with ANS dysregulation or PE, the expression frequency of CD4⁺Foxp3⁺ increased markedly after milrinone treatment, and was associated with reduction of plasma levels IL-6, IL-8 and IL-10. Plasma concentrations of cAMP were significantly decreased in patients with ANS dysregulation or PE compared with patients with HFMD or BE; however, cAMP levels increased after milrinone treatment.

Conclusions

These findings suggested decreased different regulatory T populations and cAMP expression correlate with increased EV71 disease severity. Improved outcome after milrinone treatment may associate with increased regulatory T populations, cAMP expression and modulation of cytokines levels.

Lymphocytic profiling in thyroid cancer provides clues for failure of tumor immunity

Thyroid cancers are usually surrounded by a significant number of immune-reactive cells. Tumor-associated lymphocytes as well as background lymphocytic thyroiditis are frequently mentioned in pathology reports of patients who have undergone surgery for thyroid cancer. The nature of this lymphocytic reaction is not well understood. The fact that cancer can survive in this adverse microenvironment is indicative of immune regulation. We characterized the lymphocytic infiltration that accompanies thyroid cancer and compared it with that present in thyroid autoimmunity. We found that double-negative (DN) T cells were significantly more abundant in thyroid cancer than in thyroid autoimmunity. Although FOXP3(+) regulatory T cells were also present, DN T cells were the dominant cell type, associated with thyroid cancer. Furthermore, upon stimulation, the DN T cells associated with cancer remained unchanged, while the few (<5%) DN T cells associated with thyroid autoimmunity increased in numbers (>20%). CD25 expression on DN T cells remained unchanged after stimulation, which indicates that the increase in the absolute number of DN T cells in thyroid autoimmunity was at the expense of inactivation of single-positive T cells. We concluded that in the setting of thyroid cancer, DN T cells appear to suppress tumor immunity. In contrast, in thyroid autoimmunity, DN T cells were barely present and only increased at the expense of inactivated, single-positive T cells upon induction. Together, these findings indicate that thyroid cancer-associated DN T cells might regulate proliferation and effector function of T cells and thereby contribute to tumor tolerance and active avoidance of tumor immunity.

Isolation of double negative αβ T cells from the kidney

There is currently no standard protocol for the isolation of DN T cells from the non-lymphoid tissues despite their increasingly reported involvement in various immune responses. DN T cells are a unique immune cell type that has been implicated in regulating immune and autoimmune responses and tolerance to allotransplants(1-6). DN T cells are, however, rare in peripheral blood and secondary lymphoid organs (spleen and lymph nodes), but are major residents of the normal kidney. Very little is known about their pathophysiologic function(7) due to their paucity in the periphery. We recently described a comprehensive phenotypic and functional analysis of this population in the kidney(8) in steady state and during ischemia reperfusion injury. Analysis of DN T cell function will be greatly enhanced by developing a protocol for their isolation from the kidney. Here, we describe a novel protocol that allows isolation of highly pure ab CD4+ CD8+ T cells and DN T cells from the murine kidney. Briefly, we digest kidney tissue using collagenase and isolate kidney mononuclear cells (KMNC) by density gradient. This is followed by two steps to enrich hematopoietic T cells from 3% to 70% from KMNC. The first step consists of a positive selection of hematopoietic cells using a CD45+ isolation kit. In the second step, DN T cells are negatively isolated by removal of non-desired cells using CD4, CD8, and MHC class II monoclonal antibodies and CD1d α-galcer tetramer. This strategy leads to a population of more than 90% pure DN T cells. Surface staining with the above mentioned antibodies followed by FACs analysis is used to confirm purity.

Ex vivo converted double negative T cells suppress activated B cells

Although the ability of endogenous CD4(-)CD8(-) double negative (DN) T cells to suppress B cells has been documented, the extent to which ex vivo converted DN T cells suppress B cells activity is still being explored. The aim of this study was to determine whether and what extent ex vivo converted CD4(-)CD8(-) DN T cells suppress B cell activation and antibody production. We found that ex vivo converted DN T cells suppressed proliferation of activated B cells in a perforin and cell-cell contact dependent manner. In addition, ex vivo converted DN T cells significantly inhibited the production of IgG by stimulated B cells. This study provides evidence that ex vivo converted CD4(-)CD8(-) double negative T cells can down-regulate immune responses by suppressing B cell proliferation and IgG production, and supports efforts to develop ex vivo DN T cell therapies.

Spi6 protects alloreactive CD4(+) but not CD8 (+) memory T cell from granzyme B attack by double-negative T regulatory cell

Memory T (Tm) cells pose a major barrier to long-term transplant survival. Whether regulatory T cells (Tregs)can control them remains poorly defined. Previously,we established that double-negative (DN) Tregs suppress effector T (Teff) cells. Here, we demonstrate that DNTregs effectively suppress CD4+/CD8+Teff and CD8+Tm but not CD4+Tm cells, whereas the suppression on CD8+Tm is abrogated by perforin (PFN) deficiency in DNTregs. Consistently, in a BALB/c to B6-Rag1-/-skin transplantation, transfer of DN Tregs suppressed the rejection mediated by CD4þ/CD8+Teff and CD8+Tmcells (76.0±4.9, 87.5±5.0 and 63.0±4.7 days, respectively)but not CD4þTmcells (25.3±1.4 days). Both CD8þ effector memory T and central memory T compartments significantly reduced after DN Treg transfer. CD4+Tm highly expresses granzyme B (GzmB) inhibitor serine protease inhibitor-6 (Spi6). Spi6 deficiency renders CD4þTm susceptible to DN Treg suppression. In addition,transfer of WT DN Tregs, but not PFN-/-DN Tregs,inhibited the skin allograft rejection mediated by Spi6-/-CD4þTm(75.5±7.9 days). In conclusion, CD4+ and CD8+Tm cells differentially respond toDNTregs’ suppression.The GzmB resistance conferred by Spi6 in CD4þTm cells might hint at the physiological significance of Tmpersistence

Increased IL-17 and IL-21 producing TCRαβ+CD4−CD8− T cells in Chinese systemic lupus erythematosus patients

Background: Increased numbers of TCRαβ+CD4−CD8− T cells in the peripheral blood of systemic lupus erythematosus (SLE) patients in the United States and United Kingdom have been reported. However, the proportions of TCRαβ+CD4−CD8− T cells and their involvement in the pathogenesis of SLE in Chinese populations are yet to be determined. Methods: A total of 120 SLE patients, 38 rheumatoid arthritis (RA) patients and 43 normal control subjects were examined. The proportion of TCRαβ+CD4−CD8− T cells in the peripheral blood, Fas expression on these cells, and intracellular cytokine levels in these cells were assessed using flow cytometry. Plasma cytokine concentrations were measured using enzyme-linked immunosorbent assay. Results: The percentages of TCRαβ+CD4−CD8− T cells were increased in Chinese SLE patients, particularly in active SLE patients, correlated with decreased Fas expression on these cells. IL-17 and IL-21 levels in the blood and in TCRαβ+CD4−CD8− T cells from SLE patients were increased. Moreover, a positive correlation was evident between IL-17- and IL-21-producing TCRαβ+CD4−CD8− T cells. Conclusions: Increased TCRαβ+CD4−CD8− T cells expressing inflammatory cytokines, such as IL-17 and IL-21, may be implicated in the pathogenesis of SLE in patients. Appropriate IL-17- and/or IL-21 blockage may be utilized as a novel immunotherapeutic strategy for SLE patients.

TCRγδ(+)CD4(-)CD8(-) T cells suppress the CD8(+) T-cell response to hepatitis B virus peptides, and are associated with viral control in chronic hepatitis B

The immune mechanisms underlying failure to achieve hepatitis B e antigen (HBeAg) seroconversion associated with viral control in chronic hepatitis B (CHB) remain unclear. Here we investigated the role of CD4(-)CD8(-) T (double-negative T; DNT) cells including TCRαβ(+) DNT (αβ DNT) and TCRγδ(+) DNT (γδ DNT) cells. Frequencies of circulating DNT cell subsets were measured by flow cytometry in a retrospective cohort of 51 telbivudine-treated HBeAg-positive CHB patients, 25 immune tolerant carriers (IT), 33 inactive carriers (IC), and 37 healthy controls (HC). We found that γδ DNT cell frequencies did not significantly change during treatment, being lower at baseline (P = 0.019) in patients with HBeAg seroconversion after 52 weeks of antiviral therapy (n = 20) than in those without (n = 31), and higher in the total CHB and IT than IC and HC groups (P<0.001). αβ DNT cell frequencies were similar for all groups. In vitro, γδ DNT cells suppressed HBV core peptide-stimulated interferon-γ and tumor necrosis factor-α production in TCRαβ(+)CD8(+) T cells, which may require cell-cell contact, and could be partially reversed by anti-NKG2A. These findings suggest that γδ DNT cells limit CD8(+) T cell response to HBV, and may impede HBeAg seroconversion in CHB.

Double Negative (DN) [CD3⁺CD4⁻CD8⁻] T cells correlate with disease progression during HIV infection

Although double negative T (DNT) cells (CD3⁺CD4⁻CD8⁻) share some characteristics with T regulatory cells, the relationship between DNT cells and disease progression in HIV infection is unclear. In this study, we analyzed the relationship between DNT cells and disease progression during the first 2 years of HIV infection. We found that DNT cell numbers tended to decrease with disease progression. There was a positive correlation between DNT cells and CD4 counts. The DNT cell numbers were significantly lower in the high viral load group compared with the low viral load group. Therefore, we conclude that DNT cells correlated with disease progression in HIV infection. These data provide valuable information for further understanding of the role of DNT cells during HIV infection.