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Advancing chimeric antigen receptor (CAR)-engineered adoptive T cells for the treatment of solid cancers is a major focus in the field of immunotherapy,given impressive recent clinical responses in hematological malignancies. Prostate cancer may be amenable to T cell-based immunotherapy since several tumor antigens,including prostate stem-cell antigen (PSCA),are widely over-expressed in metastatic disease. While antigen selectivity of CARs for solid cancers is crucial,it is problematic due to the absence of truly restricted tumor antigen expression and potential safety concerns with on-target off-tumor" activity. Here View Publication

Graft‐versus‐host disease is mediated by donor‐derived T cells reactive against the recipient's broadly expressed minor histocompatibility antigens (mHA). Regulatory T cells (Treg) have been explored as a therapeutic approach for chronic GVHD (cGVHD). The promising results from polyclonal Treg trials in this setting have led us to develop a Treg product specific for mismatched minor antigens between patient and donor (mTreg),circumventing broad immune suppression risks. HLA‐matched siblings of opposite sexes were used to obtain the sister's CD4+CD25hiCD127low Treg for co‐culture with the respective brother's dendritic cells as a source of mismatched mHA. We have established the optimal culture conditions resulting in the highest mTreg proliferation and viability. Comprehensive phenotyping during the ex vivo selection shows PD‐1,CTLA‐4,CD39 and HLA‐DR expression. Transcriptomic analysis revealed a switch in metabolic process,and up‐regulation of functional Treg genes. Furthermore,mTreg possess specific and potent suppressive activity,in which there is a dependency on cell‐to‐cell contact and a role for HLA class II expression on mTreg. This protocol would allow the generation of Treg specific to an array of mHA from the recipient's healthy tissues,likely providing a directed and strong suppression of cGVHD. We optimised a protocol for mHA‐specific Treg (mTreg) selection in an HLA‐matched context while defining its phenotype,transcriptional state and function. mTreg were highly activated and exerted specific,HLA class II‐,contact‐dependent suppression. This protocol can be explored as a highly personalised antigen‐specific Treg‐based therapy in future clinical trials for cGVHD. View Publication

Suppression of the cytotoxic T cell (CTL) immune response has been proposed as one mechanism for immune evasion in cancer. In this study,we have explored the underlying basis for CTL suppression in the context of B cell malignancies. We document that human B cells have an intrinsic ability to resist killing by freshly isolated cytotoxic T cells (CTLs),but are susceptible to lysis by IL-2 activated CTL blasts and CTLs isolated from immunotherapy-treated patients with chronic lymphocytic leukemia (CLL). Impaired killing was associated with the formation of dysfunctional non-lytic immune synapses characterized by the presence of defective linker for activation of T cells (LAT) signaling and non-polarized release of the lytic granules transported by ADP-ribosylation factor-like protein 8 (Arl8). We propose that non-lytic degranulation of CTLs are a key regulatory mechanism of evasion through which B cells may interfere with the formation of functional immune synapses by CTLs. View Publication

This study investigates the impact of minimal residual disease (MRD) on relapse in patients with acute myeloid leukemia (AML),focusing on its interaction with immune cells function. A total of 49 AML patients were enrolled in this prospective study and categorized into four groups: MRD − positive with relapse,MRD − positive without relapse,MRD − negative with relapse,and MRD − negative without relapse. Peripheral blood T lymphocyte subpopulations were analyzed using ten-color flow cytometry. CD4 + T cells were co-cultured with leukemia cell lines to assess the impact of CD4 + T cells on leukemia cell proliferation,apoptosis,and cytokine release. In MRD − positive patients,relapsed individuals exhibited significantly higher levels of CD4 + T cells,regulatory T (Treg) cells,and CD4 + CD45RA + naïve T cells compared to non-relapsed patients ( P < 0.0001,P = 0.0016,and P = 0.0066,respectively). Conversely,in MRD − negative patients,relapsed individuals showed a significantly lower percentage of Treg cells ( P = 0.0068). Furthermore,we observed that CD4 + T cells were associated with enhanced leukemia cell proliferation and reduced apoptosis,along with markedly increased IL-10 expression. The available data raise the possibility that CD4 + T cell-derived IL-10 participates in immune microenvironment regulation,a process that may have implications for MRD maintenance and disease recurrence in AML. View Publication

N6-methyladenosine (m6A) modification is involved in diverse immunoregulation,while the relationship between m6A modification and immune tolerance post kidney transplantation remains unclear. Expression of Wilms tumor 1-associating protein (WTAP),an m6A writer,was firstly detected in tolerant kidney transplant recipients (TOL). Then the role of WTAP on regulatory T (Treg) cell differentiation and function in CD4+ T cells from kidney transplant recipients with immune rejection (IR) was investigated. The potential target of WTAP and effect of WTAP on immune tolerance in vivo were subsequently verified. WTAP was upregulated in CD4+ T cells of TOL and positively correlated with Treg cell proportion. In vitro,WTAP overexpression promoted Treg cell differentiation and enhanced Treg cell-mediated suppression toward na?ve T cells. Forkhead box other 1 (Foxo1) was identified as a target of WTAP. WTAP enhanced m6A modification of Foxo1 mRNA in coding sequence (CDS) region,leading to up-regulation of Foxo1. Overexpression of m6A demethylase removed the effect of WTAP overexpression,while Foxo1 overexpression reversed these effects. WTAP overexpression alleviated allograft rejection in model mice,as evidenced by reduced inflammatory response and increased Treg population. Our study suggests that WTAP plays a positive role in induction of immune tolerance post kidney transplant by promoting Treg cell differentiation and function. leading to up-regulation of Foxo1. Overexpression of m6A demethylase removed the effect of WTAP overexpression while Foxo1 overexpression reversed these effects. WTAP overexpression alleviated allograft rejection in model mice as evidenced by reduced inflammatory response and increased Treg population. Our study suggests that WTAP plays a positive role in induction of immune tolerance post kidney transplant by promoting Treg cell differentiation and function." View Publication

Spontaneous control of human immunodeficiency virus (HIV) is generally associated with an enhanced capacity of CD8+ T cells to eliminate infected CD4+ T cells,but the molecular characteristics of these highly functional CD8+ T cells are largely unknown. In the present study,using single-cell analysis,it was shown that HIV-specific,central memory CD8+ T cells from spontaneous HIV controllers (HICs) and antiretrovirally treated non-controllers have opposing transcriptomic profiles. Genes linked to effector functions and survival are upregulated in cells from HICs. In contrast,genes associated with activation,exhaustion and glycolysis are upregulated in cells from non-controllers. It was shown that HIV-specific CD8+ T cells from non-controllers are largely glucose dependent,whereas those from HICs have more diverse metabolic resources that enhance both their survival potential and their capacity to develop anti-HIV effector functions. The functional efficiency of the HIV-specific CD8+ T cell response in HICs is thus engraved in their memory population and related to their metabolic programme. Metabolic reprogramming in vitro through interleukin-15 treatment abrogated the glucose dependency and enhanced the antiviral potency of HIV-specific CD8+ T cells from non-controllers. View Publication

Natural killer (NK) cells have been originally defined by their naturally occurring" effector function. However� View Publication

The viral infection of higher vertebrates elicits potent innate and adaptive host immunity. However,an excessive or inappropriate immune response also may lead to host pathology that often is more severe than the direct effects of viral replication. Therefore,several mechanisms exist that regulate the magnitude and class of the immune response. Here,we have examined the potential involvement of regulatory T (Treg) cells in limiting pathology induced by influenza A virus (IAV) infection. Using lymphocyte-deficient mice as hosts,we showed that Treg cell reconstitution resulted in a significant delay in weight loss and prolonged survival following infection. The adoptively transferred Treg cells did not affect the high rate of IAV replication in the lungs of lymphocyte-deficient hosts,and therefore their disease-ameliorating effect was mediated through the suppression of innate immune pathology. Mechanistically,Treg cells reduced the accumulation and altered the distribution of monocytes/macrophages in the lungs of IAV-infected hosts. This reduction in lung monocytosis was associated with a specific delay in monocyte chemotactic protein-2 (MCP-2) induction in the infected lungs. Nevertheless,Treg cells failed to prevent the eventual development of severe disease in lymphocyte-deficient hosts,which likely was caused by the ongoing IAV replication. Indeed,using T-cell-deficient mice,which mounted a T-cell-independent B cell response to IAV,we further showed that the combination of virus-neutralizing antibodies and transferred Treg cells led to the complete prevention of clinical disease following IAV infection. Taken together,these results suggested that innate immune pathology and virus-induced pathology are the two main contributors to pathogenesis during IAV infection. View Publication

Increasing amounts of pathogen replication usually lead to a proportionate increase in size and effector differentiation of the CD8(+) T cell response,which is attributed to increased Ag and inflammation. Using a murine CMV that is highly sensitive to the antiviral drug famciclovir to modulate virus replication,we found that increased virus replication drove increased effector CD8(+) T cell differentiation,as expected. Paradoxically,however,increased virus replication dramatically decreased the size of the CD8(+) T cell response to two immunodominant epitopes. The decreased response was due to type I IFN-dependent depletion of conventional dendritic cells and could be reproduced by specific depletion of dendritic cells from day 2 postinfection or by sterile induction of type I IFN. Increased virus replication and type I IFN specifically inhibited the response to two immunodominant epitopes that are known to be dependent on Ag cross-presented by DCs,but they did not inhibit the response to inflationary" epitopes whose responses can be sustained by infected nonhematopoietic cells. Our results show that type I IFN can suppress CD8(+) T cell responses to cross-presented Ag by depleting cross-presenting conventional dendritic cells." View Publication

The PDE2,cyclic GMP-stimulated,and the PDE4,cyclic AMP-specific enzymes provide the major,detectable cyclic AMP phosphodiesterase activities in murine thymocytes. In the absence of the cyclic GMP,PDE4 activity predominated (approximately 80% total) but in the presence of low (10 microM) cyclic GMP concentrations,PDE2 activity constituted the major PDE activity in thymocytes (approximately 80% total). The PDE4 selective inhibitor rolipram dose-dependently inhibited thymocyte PDE4 activity (IC50 approximately 65 nM). PDE2 was dose-dependently activated (EC50 approximately 1 microM) by cyclic GMP and inhibited by erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA) (IC50 approximately 4 microM). EHNA was shown to serve as a selective inhibitor of PDE-2 activity as assessed from studies using separated PDE1,PDE2,PDE3 and PDE4 species from hepatocytes as well as human PDE2 and PDE4 enzymes. EHNA completely ablated the ability of cyclic GMP to activate PDE2 activity,whilst having a much smaller inhibitory effect on the unstimulated PDE2 activity. EHNA exhibited normal Michaelian kinetics of inhibition for the cyclic GMP-stimulated PDE2 activity with Hill plots near unity. Apparent negative co-operative effect were seen in the absence of cyclic GMP with Hill coefficients of approximately 0.3 for inhibition of PDE2 activity. Within 5 min of challenge of thymocytes with the lectin phytohaemagglutinin (PHA) there was a transient decrease (approximately 83%) in PDE-4 activity and in PDE2 activity (approximately 40%). Both anti-TCR antibodies also caused an initial reduction in the PDE4 activity which was followed by a sustained and profound increase in activity. In contrast to that observed with PHA,anti-TCR/CD3 antisera had little effect on PDE2 activity. It is suggested that,dependent upon the intracellular concentrations of cyclic GMP,thymocyte cyclic AMP metabolism can be expected to switch from being under the predominant control of PDE4 activity to that determined predominantly by PDE2 activity. These activities may be rapidly and differentially regulated following ligation of different cell surface receptors. View Publication

The molecular mechanisms regulating CD8 + cytotoxic T lymphocytes (CTL) are not fully understood. Here,we show that the peroxisome proliferator–activated receptor δ (PPARδ) suppresses CTL cytotoxicity by inhibiting RelA DNA binding. Treatment of Apc Min/+ mice with the PPARδ agonist GW501516 reduced the activation of normal and tumor-associated intestinal CD8 + T cells and increased intestinal adenoma burden. PPARδ knockout or knockdown in CTLs increased their cytotoxicity against colorectal cancer cells,whereas overexpression of PPARδ or agonist treatment decreased it. Correspondingly,perforin,granzyme B,and IFNγ protein and mRNA levels were higher in PPARδ knockout or knockdown CTLs and lower in PPARδ overexpressing or agonist-treated CTLs. Mechanistically,we found that PPARδ binds to RelA,interfering with RelA–p50 heterodimer formation in the nucleus,thereby inhibiting its DNA binding in CTLs. Thus,PPARδ is a critical regulator of CTL effector function. Significance: Here,we provide the first direct evidence that PPARδ plays a critical role in suppressing the immune response against tumors by downregulating RelA DNA-binding activity. This results in decreased expression of perforin,granzyme B,and IFNγ. Thus,PPARδ may serve as a valuable target for developing future cancer immunotherapies. View Publication

RATIONALE: Tolerogenic dendritic cells and natural regulatory T cells have been implicated in the process of infectious tolerance in human allergic asthma. However,the significance of the influence of natural regulatory T cells on tolerogenic dendritic cells in the disease has not been investigated. OBJECTIVES: We aimed to characterize the mechanism of induction of the tolerogenic phenotype in circulating blood dendritic cells by allergic asthmatic natural regulatory T cells. METHODS: The study was performed in a cohort of 21 subjects with allergic asthma,21 healthy control subjects,and 21 subjects with nonallergic asthma. We cultured blood dendritic cells with natural regulatory T cells to study the induction of tolerogenic dendritic cells. Flow cytometry and proliferation assays were employed to analyze phenotype and function of dendritic cells as well as IL-10 production from natural regulatory T cells. MEASUREMENTS AND MAIN RESULTS: Dendritic cells cultured with natural regulatory T cells up-regulated IL-10,down-regulated costimulatory molecules,and stimulated the proliferation of CD4(+)CD25(-) effector T cells less potently. Allergic asthmatic natural regulatory T cells were significantly less efficient in inducing this tolerogenic phenotype of dendritic cells compared with healthy control and nonallergic asthmatic counterparts. Furthermore,this defective function of natural regulatory T cells was associated with their decreased IL-10 expression,disease severity,and could be reversed by oral corticosteroid therapy. CONCLUSIONS: These results provided the first evidences of impaired induction of tolerogenic dendritic cells mediated by natural regulatory T cells in human allergic asthma. View Publication