Role of unusual CD4<Superscript>+</Superscript> CD28<Superscript>−</Superscript> T cells in acute coronary syndrome

Acute coronary syndrome (ACS) is a group of clinical symptoms that results from complete or partial occlusive thrombus, which is caused by coronary an atherosclerotic plaque rupture or erosion. According to a recent study, CD4⁺ CD28⁻ T cells are found in atherosclerotic plaques and the peripheral circulation blood in patients with ACS, these cells play an important role in plaque ruptures. CD4⁺ CD28⁻ T cells are an unusual subset of helper cells, which expand and have harmful effects in ACS. In this review, we discuss the current issues on the generation of CD4⁺ CD28⁻ T cells and focus on their phenotypic and functional characteristics relevant to the development of cardiovascular events. Targeting the CD4⁺ CD28⁻ T cells subset in ACS could provide novel therapeutic means to prevent acute life-threatening coronary events.     

Lung cancer patients’ CD4<Superscript>+</Superscript> T cells are activated in vitro by MHC II cell-based vaccines despite the presence of myeloid-derived suppressor cells

BACKGROUND: Advanced non-small cell lung cancer (NSCLC) remains an incurable disease. Immunotherapies that activate patients' T cells against resident tumor cells are being developed; however, these approaches may not be effective in NSCLC patients due to tumor-induced immune suppression. A major cause of immune suppression is myeloid-derived suppressor cells (MDSC). Because of the strategic role of CD4(+) T lymphocytes in the activation of cytotoxic CD8(+) T cells and immune memory, we are developing cell-based vaccines that activate tumor-specific CD4(+) T cells in the presence of MDSC. The vaccines are NSCLC cell lines transfected with costimulatory (CD80) plus major histocompatibility complex class II (MHC II) genes that are syngeneic to the recipient. The absence of invariant chain promotes the presentation of endogenously synthesized tumor antigens, and the activation of MHC II-restricted, tumor-antigen-specific CD4(+) T cells. METHODS: Potential vaccine efficacy was tested in vitro by priming and boosting peripheral blood mononuclear cells from ten NSCLC patients who had varying levels of MDSC. CD4(+) T cell activation was quantified by measuring Type 1 and Type 2 cytokine release. RESULTS: The vaccines activated CD4(+) T cells from all ten patients, despite the presence of CD33(+)CD11b(+) MDSC. Activated CD4(+) T cells were specific for NSCLC and did not cross-react with tumor cells derived from non-lung tissue or normal lung fibroblasts. CONCLUSIONS: The NSCLC vaccines activate tumor-specific CD4(+) T cells in the presence of potent immune suppression, and may be useful for the treatment of patients with NSCLC.     

Defective CD4<Superscript>+</Superscript>CD25<Superscript>+</Superscript>regulatory T cell functioning in collagen-induced arthritis: an important factor in pathogenesis,counter-regulated by endogenous IFN-γ

Mice with a deficiency in IFN-γ or IFN-γ receptor (IFN-γR) are more susceptible to collagen-induced arthritis (CIA), an experimental autoimmune disease that relies on the use of complete Freund's adjuvant (CFA). Here we report that the heightened susceptibility of IFN-γR knock-out (KO) mice is associated with a functional impairment of CD4⁺CD25⁺ T_reg cells. Treatment of wild-type mice with depleting anti-CD25 antibody after CFA-assisted immunisation with collagen type II (CII) significantly accelerated the onset of arthritis and increased the severity of CIA. This is an indication of a role of T_reg cells in the effector phase of CIA. IFN-γR deficiency did not affect the number of CD4⁺CD25⁺ T cells in the central and peripheral lymphoid tissues. In addition, CD4⁺CD25⁺ T cells isolated from naive IFN-γR KO mice had a normal potential to suppress T cell proliferation in vitro. However, after immunisation with CII in CFA, the suppressive activity of CD4⁺CD25⁺ T cells became significantly more impaired in IFN-γR-deficient mice. Moreover, expression of the mRNA for Foxp3, a highly specific marker for T_reg cells, was lower. We further demonstrated that the effect of endogenous IFN-γ, which accounts for more suppressive activity in wild-type mice, concerns both T_reg cells and accessory cells. Our results demonstrate that the decrease in T_reg cell activity in CIA is counter-regulated by endogenous IFN-γ.     

Peripheral survival of naïve CD8<Superscript>+</Superscript> T cells

Maintenance of a sufficient population of naïve CD8⁺ T cells in the peripheral lymphoid compartment is critical for immunocompetence. Peripheral T cell number is a function of T cell generation, survival, and death. Homeostasis, a critical balance between survival and death, must exist to prevent either lymphopenia or lymphocytosis. In the current review, we discuss known requirements for the survival of naïve peripheral CD8⁺ T cells as well as mechanisms of death when survival signals are lost. We also discuss associations between survival and homeostasis-driven proliferation, and highlight the gaps in our knowledge of these critical processes.     

Characterization of MHC class-I restricted TCRαβ<Superscript>+</Superscript> CD4<Superscript>−</Superscript> CD8<Superscript>−</Superscript> double negative T cells recognizing the gp100 antigen from a melanoma patient after gp100 vaccination

The immune attack against malignant tumors require the concerted action of CD8⁺ cytotoxic T lymphocytes (CTL) as well as CD4⁺ T helper cells. The contribution of T cell receptor (TCR) αβ⁺ CD4⁻ CD8⁻ double-negative (DN) T cells to anti-tumor immune responses is widely unknown. In previous studies, we have demonstrated that DN T cells with a broad TCR repertoire are present in humans in the peripheral blood and the lymph nodes of healthy individuals. Here, we characterize a human DN T cell clone (T4H2) recognizing an HLA-A2-restricted melanoma-associated antigenic gp100-peptide isolated from the peripheral blood of a melanoma patient. Antigen recognition by the T4H2 DN clone resulted in specific secretion of IFN-γ and TNF. Although lacking the CD8 molecule the gp100-specifc DN T cell clone was able to confer antigen-specific cytotoxicity against gp100-loaded target cells as well as HLA-A2⁺ gp100 expressing melanoma cells. The cytotoxic capacity was found to be perforin/granzymeB-dependent. Together, these data indicate that functionally active antigen-specific DN T cells recognizing MHC class I-restricted tumor-associated antigen (TAA) may contribute to anti-tumor immunity in vivo. A. Mackensen and K. Fischer contributed equally to this work and should be considered joint senior authors. This work was supported by the Deutsche Forschungsgemeinschaft (MA 1351/5-1, KFO 146) and NIH grants CA90873, CA102280, 104947 (MIN). Companion paper: “Relationship between CD8-dependent antigen recognition, T cell functional avidity, and tumor cell recognition” by Tamson V. Moore et al. doi: .     

Assessment of CD4<Superscript>+</Superscript> T cells specific for the tumor antigen SSX-1 in cancer-free individuals

Proteins encoded by genes of the SSX family are specifically expressed in tumors and are therefore relevant targets for cancer immunotherapy. One of the first identified family members, SSX-1, is expressed in a large fraction of synovial sarcomas as a fusion protein together with the product of the SYT gene. In addition, the full-length SSX-1 antigen is frequently expressed in tumors of several other histological types such as sarcoma, melanoma, hepatocellular carcinoma, ovarian cancer and myeloma. To date, however, SSX-1 specific T cell responses have not been investigated and no SSX-1 derived T cell epitopes have been described. Here, we have assessed the presence of CD4(+) T cells directed against the SSX-1 antigen in circulating lymphocytes of cancer-free individuals. After a single in vitro stimulation with a pool of peptides spanning the entire SSX-1 protein we could detect and isolate SSX-1-specific CD4(+) T cells from 5/5 donors analyzed. SSX-1-specific polyclonal populations isolated from these cultures recognized peptides located in three distinct regions of the protein containing clusters of sequences with significant predicted binding to frequently expressed MHC class II alleles. Characterization of specific clonal CD4(+) T cell populations derived from one donor allowed the identification of several naturally processed epitopes recognized in association with HLA-DR. These data document the existence of a significant repertoire of CD4(+) T cells specific for SSX-1 derived sequences in circulating lymphocytes of any individual that can be exploited for the development of both passive and active immunotherapeutic approaches to control disease evolution in cancer patients.     

Preliminary study: Treatment with intramuscular interferon beta-1a results in increased levels of IL-12Rβ2<Superscript>+</Superscript> and decreased levels of IL23R<Superscript>+</Superscript> CD4<Superscript>+</Superscript> T - Lymphocytes in multiple sclerosis

Background  

There are a lack of biomarkers which can be used to predict clinical outcomes for multiple sclerosis (MS) patients receiving interferon beta (IFN-β). Thus the objective of this study was to characterize changes in CD4+ T-lymphocyte expression in an unbiased manner following initiation of intramuscular (IM) IFN-β-1a treatment, and then to verify those findings using marker-specific assays.     

IL-4 inducibility in NKT cells,naïve CD4<Superscript>+</Superscript> T cells and TCR-γ δ T cells

NKT cells, na?ve CD4(+) T cells, and TCR-gammadelta T cells belong to distinct T cell lineages but all express T cell receptors generated through random combinatorial joining of V-(D)-J genes. These distinct lineage T cells also possess the property of promptly activating the IL-4 gene upon T cell receptor stimulation. A comparative accounting of features as they pertain to IL-4 inducibility in these three distinct lineage T cells is provided here.     

TGF-β modulates the functionality of tumor-infiltrating CD8<Superscript>+</Superscript> T cells through effects on TCR signaling and Spred1 expression

This study demonstrates that CD8⁺ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-β contributed markedly to the tumor-infiltrating CD8⁺ T cells’ (TILs) reduced functionality, which could be reversed using a small molecule TGF-β inhibitor. Upon T-cell receptor (TCR) activation, the activation of ITK and ERK kinases were reduced in CD8⁺ TILs, as compared to splenic CD8⁺ T cells: TGF-β inhibitor could reverse this phenomenon. This study demonstrates for the first time the association of the Spred-1 gene, an inhibitor of the Ras/MAPK pathway, with CD8⁺ TILs and TGF-β activity. Spred-1 was upregulated in CD8⁺ TILs and TGF-β enhanced the expression of Spred-1 in effector/memory CD8⁺ T cells and not in rested/memory CD8⁺ T cells. Based on these findings, this study supports the hypothesis that TGF-β mediates an inhibitory mechanism on CD8⁺ TILs involving TCR-signaling blockade and the upregulation of Spred-1, thus implicating Spred-1 as a potential new target for future anti-tumor immune studies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. M. G. di Bari and M. E. C. Lutsiak contributed equally to this work.     

Identification of Hydroxysteroid (17β) dehydrogenase type 12 (HSD17B12) as a CD8<Superscript>+</Superscript> T-cell-defined human tumor antigen of human carcinomas

Hydroxysteroid (17β) dehydrogenase type 12 (HSD17B12) is a multifunctional isoenzyme functional in the conversion of estrone to estradiol (E2), and elongation of long-chain fatty acids, in particular the conversion of palmitic to archadonic (AA) acid, the precursor of sterols and the inflammatory mediator, prostaglandin E₂. Its overexpression together with that of COX-2 in breast carcinoma is associated with a poor prognosis. We have identified the HSD17B12_114–122 peptide (IYDKIKTGL) as a naturally presented HLA-A*0201 (HLA-A2)-restricted CD8⁺ T-cell-defined epitope. The HSD17B12_114–122 peptide, however, is poorly immunogenic in its in vitro ability to induce peptide-specific CD8⁺ T cells. Acting as an “optimized peptide”, a peptide (TYDKIKTGL), which is identical to the HSD17B12_114–122 peptide except for threonine at residue 1, was required for inducing in vitro the expansion of CD8⁺ T-cell effectors cross-reactive against the HSD17B12_114–122 peptide. In IFN-γ ELISPOT assays, these effector cells recognize HSD17B12_114–122 peptide-pulsed target cells, as well as HLA-A2⁺ squamous cell carcinoma of the head and neck (SCCHN) and breast carcinoma cell lines overexpressing HSD17B12 and naturally presenting the epitope. Whereas growth inhibition of a breast carcinoma cell line induced by HSD17B12 knockdown was only reversed by AA, in a similar manner, the growth inhibition of the SCCHN PCI-13 cell line by HSD17B12 knockdown was reversed by E2 and AA. Our findings provide the basis for future studies aimed at developing cancer vaccines for targeting HSD17B12, which apparently can be functional in critical metabolic pathways involved in inflammation and cancer.     

<Emphasis Type="Italic">SNCA</Emphasis> alleles rs356219 and rs356165 are associated with Parkinson’s disease and increased α-synuclein gene expression in CD45<Superscript>+</Superscript> blood cells

Impaired metabolism of α-synuclein (SNCA) and its aggregation are key molecular events underlying Parkinson’s disease (PD). Emerging data show that there is a connection between PD and the gene locus containing the SNCA gene. Meta-analyses have demonstrated a highly significant PD connection with single nucleotide polymorphisms (SNPs) rs356165 (A/G) and rs356219 (A/G) in the SNCA gene. We conducted SNP genotyping in 260 PD patients (n = 260) and 262 healthy people (n = 262) from northwestern regions of Russia. Linkage disequilibrium was registered between rs356219 and rs356165 alleles (D' = 0.926). It was confirmed that G alleles (rs356165 and rs356219) are associated with increased risk of PD development. For the first time, we have evaluated the relationship between rs356165 and rs356219 and levels of SNCA mRNA and α-synuclein protein in CD45⁺ peripheral blood cells in drug-naïve PD patients (n = 43) and controls (n = 39). Both the level of mRNA SNCA gene and that of α-synuclein protein were increased in carriers of rs356219 and rs356165 compared to carriers with AA genotype in control group (in the group of healthy people) (p = 0.046 and p = 0.039, respectively). Linkage disequilibrium was shown between associated marker alleles. Our data suggest that rs356165 and rs356219 allele variants may affect the PD development by up-regulation of SNCA expression.