scholarly journals Novel Role of p53 in Septic Immunosuppression: Involvement in Loss and Dysfunction of CD4+ T Lymphocytes

2018 ◽  
Vol 51 (1) ◽  
pp. 452-469 ◽  
Author(s):  
Hui Zhang ◽  
Cheng-Feng Xu ◽  
Chao Ren ◽  
Tian-Tian Wu ◽  
Ning Dong ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Lymphocytes ◽  
Cell Loss ◽  
Immune Dysfunction ◽  
Jurkat Cells ◽  
Cell Counting ◽  
Genetic Knockout

Background/Aims: Immunosuppression frequently occurs during the development of sepsis and is closely associated with poor outcome. Characteristics of immunosuppressive CD4+ T lymphocytes in sepsis have been reported to include dramatic cell loss and inactivation. p53 acts as a pivotal transcription factor in regulating cell proliferation and apoptosis, which control tumorigenesis. However, few studies have investigated the universal role of p53 in immune cells, especially in the development of sepsis. Methods: A mouse model of sepsis was produced by cecal ligation and puncture (CLP), and isolated splenic CD4+ T cells or Jurkat cells were exposed to lipopolysaccharide (LPS) stimulation in vitro. We used genetic knockout (p53-/-) mice or the specific inhibitor pifithrin-α (PFT) to investigate the regulatory mechanisms of p53. Cell proliferation ability was assessed using a Cell Counting Kit-8 assay, and apoptotic cells were stained with annexin V/propidium iodide and then analyzed using a FACScan flow cytometer. Protein and mRNA expression levels were measured by western blotting and real-time PCR, and cytokine levels in culture supernatants were determined by enzyme-linked immunosorbent assay. Results: Splenic CD4+ T lymphocytes from CLP mice expressed gradually elevated p53 mRNA and protein levels, which resulted in extracellular regulated protein kinase 1/2 inactivation and expression of apoptotic molecules. Specific inhibition of p53 by PFT or genetic knockout (p53-/-) maintained CD4+ T lymphocyte homeostasis, as indicated by protection from cell loss and restoration of immune function. A medium dose of PFT improved the survival rate of mice, while mortality rate showed only a slight improvement in p53-/- mice compared with wild-type mice. The in vitro responses to LPS were consistent with these results, and upregulation of p53 clearly affected the proliferation, apoptosis, and immune dysfunction of CD4+ T lymphocytes. In addition, we confirmed the regulatory effect of p53 in Jurkat cells, and inhibition of p53 by either inhibition or short hairpin RNA transduction markedly protected cells from LPS stimulation. Conclusion: Elevation of p53 in T lymphocytes during sepsis or endotoxin challenge might be responsible for inhibiting cell proliferation and enhancing both apoptosis and immune dysfunction of T cells.

miR-369-3p serves as prognostic factor and regulates cancer progression of hepatocellular carcinoma

2021 ◽  
Author(s):  
Can Chen ◽  
Yi Zong ◽  
Jiaojiao Tang ◽  
Ruisheng Ke ◽  
Lizhi Lv ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Proliferation ◽  
Cancer Progression ◽  
Cell Counting ◽  
Migration And Invasion ◽  
Pcr Analysis ◽  
Reverse Transcription Pcr ◽  
Huh7 Cells

Background: The aim of this study was to investigate the role of miR-369-3p in hepatocellular carcinoma (HCC). Materials & methods: The expression levels of miR-369-3p were detected using the quantitative real-time reverse transcription-PCR analysis. The cell counting kit-8 and transwell assays were used to explore the effects of miR-369-3p on cell proliferation, migration and invasion of HCC cells. Results: The miR-369-3p expression was downregulated in HCC tissues and cell lines, in comparison to the normal controls, respectively. In vitro, overexpression of miR-369-3p in Hep 3B and Huh7 cells inhibited cell proliferation, migration and invasion. SOX4 was a direct target of miR-369-3p. Conclusion: Our results suggested that miR-369-3p may be a tumor suppressor in HCC by targeting SOX4.

scholarly journals Influenza virus-specific CD4+ T helper type 2 T lymphocytes do not promote recovery from experimental virus infection.

1994 ◽  
Vol 180 (4) ◽  
pp. 1273-1282 ◽  
Author(s):  
M B Graham ◽  
V L Braciale ◽  
T J Braciale
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Lymphocytes ◽  
Cd4 T Cells ◽  
Primary Role ◽  
T Helper ◽  
Helper Type

T lymphocytes play a primary role in recovery from viral infections and in antiviral immunity. Although viral-specific CD8+ and CD4+ T cells have been shown to be able to lyse virally infected targets in vitro and promote recovery from lethal infection in vivo, the role of CD4+ T lymphocytes and their mechanism(s) of action in viral immunity are not well understood. The ability to further dissect the role that CD4+ T cells play in the immune response to a number of pathogens has been greatly enhanced by evidence for more extensive heterogeneity among the CD4+ T lymphocytes. To further examine the role of CD4+ T cells in the immune response to influenza infection, we have generated influenza virus-specific CD4+ T cell clones from influenza-primed BALB/c mice with differential cytokine secretion profiles that are defined as T helper type 1 (Th1) clones by the production of interleukin 2 (IL-2) and interferon gamma (IFN-gamma), or as Th2 clones by the production of IL-4, IL-5, and IL-10. Our studies have revealed that Th1 clones are cytolytic in vitro and protective against lethal challenge with virus in vivo, whereas Th2 clones are noncytolytic and not protective. Upon further evaluation of these clonal populations we have shown that not only are the Th2 clones nonprotective, but that pulmonary pathology is exacerbated as compared with control mice as evidenced by delayed viral clearance and massive pulmonary eosinophilia. These data suggest that virus-specific CD4+ T cells of the Th2 subset may not play a primary role in virus clearance and recovery and may lead to immune mediated potentiation of injury.

Coordinate expression and proliferative role of HOXB genes in activated adult T lymphocytes

1994 ◽  
Vol 14 (7) ◽  
pp. 4872-4877
Author(s):  
A Carè ◽  
U Testa ◽  
A Bassani ◽  
E Tritarelli ◽  
E Montesoro ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Retinoic Acid ◽  
T Cell ◽  
T Lymphocytes ◽  
T Cell Activation ◽  
Cell Activation ◽  
Rnase Protection ◽  
Activated T Lymphocytes

We investigated the expression of HOXB cluster genes in purified phytohemagglutinin (PHA)-activated T lymphocytes from normal adult peripheral blood by reverse transcription PCR and RNase protection. These genes are not expressed in quiescent T cells, except for barely detectable B1 RNA. After the PHA stimulus, HOXB gene activation initiates coordinately as a rapid induction wave in the 3'-->5' cluster direction (i.e., from HOXB1 through B9 genes). Thus, (i) expression of the foremost 3'-located B1 and B2 genes peaks 10 min after PHA addition and then rapidly declines, (ii) activation of B3, B4, and B5 begins 10 min after PHA addition and peaks at later times (i.e., at 120 min for B5), (iii) B6, B7, and B9 are expressed at a low level starting at later times (45 to 60 min), and (iv) B8 remains silent. Treatment of PHA-activated T lymphocytes with antisense oligonucleotides to B2 or B4 mRNA causes a drastic inhibition of T-cell proliferation and a decreased expression of T-cell activation markers (i.e., interleukin 2 and transferrin receptors). Similarly, treatment of CEM-CCRF, Peer, and SEZ627 T acute lymphocytic leukemia cell lines with anti-B4 oligomer markedly inhibits cell proliferation. Finally, T cells stimulated by a low dosage of PHA in the presence of 1 microM retinoic acid show a marked increase of both HOXB expression, particularly B2, and cell proliferation. These studies provide novel evidence on the role of HOX genes in adult cell proliferation. (i) Coordinate, early activation of HOXB genes from the 3'-->5' cluster side apparently underlies T-cell activation. (ii) The expression pattern in adult PHA-activated T cells is strikingly similar to that observed in retinoic acid-induced teratocarcinoma cells (A. Simeone, D. Acampora, L. Arcioni, P. W. Andres, E. Boncinelli, and F. Mavilio, Nature (London) 346:763-766, 1990), thus suggesting that molecular mechanisms underlying HOX gene expression in the earliest stages of development may also operate in activated adult T lymphocytes.

scholarly journals LncRNA EBLN3P promotes the progression of osteosarcoma through modifying the miR-224-5p/Rab10 signaling axis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuhong Dai ◽  
Ning Li ◽  
Ming Zhou ◽  
Yue Yuan ◽  
Ding Yue ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Cell Counting ◽  
Luciferase Assay ◽  
Migration And Invasion ◽  
Osteosarcoma Cell ◽  
Regulatory Loop

AbstractThe treatment of patients with advanced-stage osteosarcoma represents a major challenge, with very few treatments currently approved. Although accumulating evidence has demonstrated the importance of lncRNAs in osteosarcoma, the current knowledge on the functional roles and molecular mechanisms of lncRNA endogenous born avirus-like nucleoprotein (EBLN3P) is limited. At present, the expressions of EBLN3P and miR-224-5p in osteosarcoma tissues were quantified by reverse transcription-quantitative PCR assay, and the expression of Ras-related protein 10 (Rab10) in osteosarcoma tissues was quantified by immunohistochemistry and western-blotting. The bioinformatics prediction software ENCORI was used to predict the putative binding sites of EBLN3P, Rab10 and miR-224-5p. The regulatory role of EBLN3P or miR-224-5p on cell proliferation, migration and invasion ability were verified by Cell Counting Kit-8, wound healing and Transwell assays, respectively. The interaction among EBLN3P, miR-224-5p and Rab10 were testified by luciferase. The increased expression of EBLN3P and Rab10 and decreased expression of miR-224-5p were observed in osteosarcoma tissues and cell lines. Besides, the overexpression of EBLN3P or knockdown of miR-224-5p were revealed to promote the proliferation, migration and invasion of osteosarcoma cells. Bioinformatics analysis and luciferase assay revealed that EBLN3P could directly interacted with miR-224-5p to attenuate miR-224-5p binding to the Rab10 3′-untranslated region. Furthermore, the mechanistic investigations revealed activation of the miR-224-5p/Rab10 regulatory loop by knockdown of miR‐372-3p or overexpression of Rab10, thereby confirming the in vitro role of EBLN3P in promoting osteosarcoma cell proliferation, migration and invasion. To the best of our knowledge, the present study is the first to demonstrate that EBLN3P may act as a competitive endogenous RNA to modulate Rab10 expression by competitive sponging to miR-224-5p, leading to the regulation of osteosarcoma progression, which indicates a possible new approach to osteosarcoma diagnosis and treatment.

Two Novel WT-1 Derived Peptides Induce CD4+ peptide–specific T Cell Proliferation in Patients with Myelodysplastic Syndrome (MDS)

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5432-5432
Author(s):  
Monica Bocchia ◽  
Micaela Ippoliti ◽  
Marzia Defina ◽  
Rosaria Crupi ◽  
Maristella Tassi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cytotoxic Activity ◽  
Cd4 T Cells ◽  
Cd4 T Cell ◽  
T Cell Proliferation ◽  
Wt1 Protein

Abstract The Wilms tumor gene WT1 is overexpressed in hematopoietic malignancies such as Myelodysplastic syndromes and leukemias and the WT1 protein was demonstrated to be an attractive target antigen for an immunotherapeutic approach to these diseases. Most of the efforts have been focused to the search for immunogenic peptides suitable for inducing cytotoxic T lymphocytes (CTLs) and to less extent for CD4+ T lymphocytes with potential cytotoxic activity. On this matter, in our previous experience with a p210-derived peptide vaccine developed for chronic myeloid leukemia patients with minimal residual disease, the main immune and therapeutic effect observed after vaccinations appeared to be mediated by peptide-specific CD4+ T cells induced by the longest peptide (25 mer) included in our vaccine. CML-peptide specific T cells were found to be either CD4+/perforin+ or CD4+/CD25+/Foxp3+ and we recently showed their direct cytotoxicity against a CML cell line. Thus to pursue a vaccine strategy mainly devoted to a similar CD4+ T cell immune response, we screened WT1 protein through Syfpeithi database to identify original peptides with a suitable length (23–25 amino acids) to be processed by several HLA class II molecules and to induce a strong CD4+ T cell stimulation. Additionally, in order to maximize the immunogenic potential of the novel peptides, we focused our attention on areas of the protein with known CTLs/CD4 T cells immunogenic epitopes. We identified two peptides that fulfilled these requirements: SEPQQMGSDVRDLNALLPAVPSLGG (WT1-iso5 64–88) which includes 5 amino acid from the alternative splicing derived isoform 5 of WT1 and the first 20 aa of “canonical” WT1 sequence and RPFMCAYPGCNKRYFKLSHLQMHSR (WT1321–345). Both 25mer peptides showed strong HLA binding properties for HLA-DRB1*0101, HLADRB1* 0401, HLA-DRB1*0701, HLA-DRB1*1101, HLA-DRB1*1501 and HLADRB1* 0301( DR17). We first tested them in vitro for their capability to induce peptide-specific CD4+ T cells. Briefly, CD4+ T cells freshly isolated from PBMC were cultured for 21 days in 5% AB human serum media while undergoing to 3 rounds of stimulation with autologous CD14+ cells and both WT1-iso5 64–88 and WT1 321–345 peptides at 20μg/ml in the presence of IL-15. This in vitro stimulation was performed in 3 normal subjects and in 3 MDS patients with high levels of bone marrow WT1 transcript (2 patients presenting a low-International Prognostic Scoring System (IPSS) refractory anemia (RA) and 1 with intermediate IPSS RA). In all 3 healthy donors tested, both peptides were able to induce peptide specific CD4+ T cell proliferation as measured by standard 3HThymidine assay, with a stimulation index (SI) ranging from 2.0 to 2.5 regardless of their HLA-DR phenotype ( SI= cpm CD4+ T cells plus test peptides/CD4+ T cell alone or CD4+ T cells plus control peptides; peptide-specific T cell proliferation was considered positive for SI≥2). Similar results were obtained in all 3 MDS patients in which WT1-iso5 64–88 and WT1 321–345 induced peptide-specific CD4+ T cell proliferation with a SI value of 2.5, 2.9 and 3.0 respectively. In conclusion the present study identified 2 novel WT1-derived 25 mer peptides which were able to easily induce in vitro a peptide-specific CD4+ T cell response in MDS patients. WT1-specific CD4+ T cells proliferated with similar SI values in normal donors and in WT1 positive MDS patients, the latter being highly exposed to this antigen and thus potentially tolerant to it. A possible cytotoxic activity of these WT1-specific CD4+ T cells is under evaluation and in vivo vaccinations of low-intermediate IPSS MDS patients with these peptides are planned.

scholarly journals Interleukin-35 promotes progression of prostate cancer and inhibits anti-tumour immunity

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Jialin Zhu ◽  
Yan Wang ◽  
Dai Li ◽  
Haonan Zhang ◽  
Zhi Guo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Proliferation ◽  
T Cells ◽  
Cd8 T Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tumour Immunity ◽  
Immunohistochemical Stains

Abstract Background Interleukin-35 (IL-35) has been reported to play an important role in the progression of cancers. The role of IL-35 in prostate cancer (PCA) is not well understood. In this study, we investigated the effects of IL-35 on PCA and its immunoregulatory effect on PCA. Methods The protein and mRNA expression of IL-35 in PCA cells was detected by western blot and RT-PCR. The invasion and migration of cells were detected using transwell and wound‐healing assays. A CCK-8 assay was conducted to observe cell proliferation. In vivo, IL-35 plasma concentration was test by enzyme-linked immunosorbent assay. The role of IL-35 in tumour cell proliferation and angiogenesis of mice was detected by immunohistochemical stains. The mouse survival and tumour volumes were calculated, and lung metastasis rate was detected by HE staining. The modulatory effects of IL-35 on myeloid-derived inhibitory cells (MDSCs), regulatory T cells (Tregs), CD4+ T cells and CD8+ T cells from PCA mice were investigated by immunohistochemical stains and flow cytometry. Results High levels of IL-35 significantly promoted the migration, invasion and cell proliferation of PCA cells in vitro. IL-35 was associated with tumour growth, metastasis and poor prognosis in PCA mice. Additionally, high levels of IL-35 significantly increased the proportions of MDSCs and Tregs and decreased the proportions of CD4+ and CD8+ T cells in the spleen, blood and tumour microenvironment. The IL-35 neutralizing antibody played the opposite role. Conclusions IL-35 contributed to the progression of PCA through promoting cell proliferation and tumour angiogenesis. IL-35 might limit the anti-tumour immune response by upregulating the proportions of Tregs and MDSCs and by reducing the proportions of CD4+ and CD8+ T cells. IL-35 might serve as a novel therapeutic target for PCA.

scholarly journals Host Restriction Factors Modulating HIV Latency and Replication in Myeloid Cells

2021 ◽  
Author(s):  
Guido Poli ◽  
Isabel Pagani ◽  
Pietro Demela ◽  
Silvia Ghezzi ◽  
Elisa Vicenzi
Keyword(s):  
T Cells ◽  
T Lymphocytes ◽  
Virus Replication ◽  
Myeloid Cells ◽  
Viral Reservoir ◽  
Restriction Factors ◽  
Virtual Absence ◽  
Hiv 1

In addition to CD4+ T lymphocytes, myeloid cells, and, particularly, differentiated macrophages, are targets of the human immunodeficiency virus type-1 (HIV-1) infection via interaction of gp120Env with CD4 and CCR5 or CXCR4. Both T cells and macrophages support virus replication although with substantial differences. In contrast to activated CD4+ T lymphocytes, HIV-1 replication in macrophages occurs in nondividing cells and it is characterized by virtual absence of cytopathicity both in vitro and in vivo. These general features should be considered in evaluating the role of cell-associated restriction factors aiming at preventing of curtailing virus replication in macrophages and T cells particularly in the context of designing strategies to tackle the viral reservoir in infected individuals receiving combination antiretroviral therapy. In this regard, we will here also discuss a model of reversible HIV-1 latency in primary human macrophages and the role of host factor determining restriction or reactivation of virus replication in myeloid cells.

scholarly journals Susceptibility of Bovine Antigen-Presenting Cells to Infection by Bovine Herpesvirus 1 and In Vitro Presentation to T Cells: Two Independent Events

1999 ◽  
Vol 73 (6) ◽  
pp. 4840-4846 ◽  
Author(s):  
Ximena Renjifo ◽  
Carine Letellier ◽  
Günther M. Keil ◽  
Jamila Ismaili ◽  
Alain Vanderplasschen ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Bovine Herpesvirus ◽  
T Cell Proliferation ◽  
Bovine Herpesvirus 1 ◽  
Herpesvirus 1 ◽  
Antigen Presenting

ABSTRACT The aim of the present study was to develop an in vitro system for presentation of bovine herpesvirus 1 (BHV-1) antigens to bovine T lymphocytes and to characterize the antigen-presenting cells (APC) which efficiently activate CD4+ T cells. Two approaches were used to monitor the infection of APC by BHV-1 as follows: (i) detection of viral glycoproteins at the cell surface by immunofluorescence staining and (ii) detection of UL26 transcripts by reverse transcription-PCR. The monocytes were infected, while dendritic cells (DC) did not demonstrate any detectable viral expression. These data suggest that monocytes are one site of replication, while DC are not. The capacities of monocytes and DC to present BHV-1 viral antigens in vitro were compared. T lymphocytes (CD2+ or CD4+) from BHV-1 immune cattle were stimulated in the presence of APC previously incubated with live or inactivated wild-type BHV-1. DC stimulated strong proliferation of Ag-specific T cells, while monocytes were poor stimulators of T-cell proliferation. When viral attachment to the surface of the APC was inhibited by virus pretreatment with soluble heparin, T-cell proliferation was dramatically decreased. Unexpectedly, incubation of DC and monocytes with the deletion mutant BHV-1 gD−/−, which displays impaired fusion capacity, resulted in strong activation of T lymphocytes by both APC types. Collectively, these results indicate that presentation of BHV-1 antigens to immune T cells is effective in the absence of productive infection and suggest that BHV-1 gD−/− mutant virus could be used to induce virus-specific immune responses in cattle.

TCR and DNAM Dependent Lysis of Acute Monocytic Leukemia (AMoL) by Vg9Vd2 T Lymphocytes.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1041-1041
Author(s):  
Julie Gertner-Dardenne ◽  
Eloise Perrot ◽  
Thomas Prebet ◽  
Aude Charbonnier ◽  
Helene Sicard ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
T Lymphocytes ◽  
Myeloid Leukemia ◽  
Ex Vivo ◽  
Acute Myeloid

Abstract Abstract 1041 Poster Board I-63 BACKGROUNd: Compelling evidences have demonstrated the role of the immune system in the control of acute myeloid leukemia (AML). So far, T cells and natural killer (NK) cells are the major immune effectors shown to be involved in AML control. The graft-versus-leukemia (GVL) effect following allogenic stem cell transplantation as well as donor lymphocyte infusions indicate that T lymphocytes can control and eliminate AML cells. Leukemia-specific antigenic peptides have been characterized (proteinase-3 and Wilms tumor 1 protein) and serve as targets for peptide-based vaccine trials in AML. Allogenic NK cells have anti-leukemic activity as shown by killer cell inhibitory receptor (KIR)-mismatched haplo-identical stem cell transplantation. Less is known regarding the role of gd T cells in the control of AML. Recently the reconstitution of Vd1 T lymphocytes post transplantation has been shown to correlate with a better prognosis. In the present study, we have analyzed gd T cells in patients with AML and in a mouse model of human AML and focused on (Vg9) Vd2 T cells, the main subset of circulating gd T cells with anti-neoplastic activity. Human Vg9Vd2 T lymphocytes can be activated by nonpeptidic antigens such as the mevalonate pathway-derived isopentenyl pyrophosphate or synthetic phosphoantigen such as bromohydrin pyrophosphate (BrHPP). This population may be suitable for the adoptive immunotherapy of acute myeloid leukemia (AML). However little is known about the frequency, the function and the mechanisms underlying Vg9Vd2 T-cell recognition of AML. We have focused this study on AMoL which are targets of NK and ab T cells. OBJECTIVE OF THE STUDY to describe Vg9Vd2 T cells in patients with AML and investigate their ability to induce an effective cytotoxic response against autologous AML blast in vitro and in vivo. EXPERIMENTAL PROCEDURe: We compared the phenotype and the absolute circulating Vg9Vd2 T cell levels in the blood and the bone marrow (BM) in 12 patients with AMoL (FAB AML-M4 and -M5) and 12 healthy volunteers (HV) using multi parametric flow cytometry. All patients and volunteers gave written informed consent. Vg9Vd2 T cells of AML patient were expanded ex vivo using BrHPP or Zoledronic acid plus IL2. The functions of expanded Vg9Vd2 T cells were assessed in vitro by their cytotoxicity against leukemic blasts (CD107a staining, 51Cr assay) and in vivo in immunodeficient mice transplanted with human AML cell line (U937). In these experiments, the ability of adoptively transferred Vg9Vd2 T cells to migrate into BM and improve mice survival was assessed after i.v. infusion of U937 cells into healthy female NOD-SCID, common _-chain knockout mice (NOG mice). Mice were then treated twice i.v. with 40.106 Vg9Vd2 T cells. RESULTs: Vg9Vd2 T lymphocytes are present in the blood as well as BM of AMoL patients at a lower frequency as compared to HV (median 2.07/μl vs 34/μL respectively P<0.001). Vg9Vd2 T lymphocytes from AML patients are endowed with in vitro proliferation in response to BrHPP or Zoledronic acid plus IL2 but lower than HV (fold increase median 33 versus 69, P=0.051). Expanded Vg9Vd2 express activation markers (CD69 and CCR5) and exhibit an effector/memory phenotype (CD45RA- CD27-). Their lytic potential toward autologous AML blast was equivalent to those of HV by 51Cr experiments and CD107a staining and involves the perforin-granzyme pathway. Their activity depends on both TCRVd2 and DNAX accessory molecule-1 (DNAM-1) as demonstrated by antibody blockade. In vivo data show that, upon sacrifice, Vg9Vd2 were detected in BM, spleen and blood of mice. Preliminary Kaplan-Meier analysis of pooled cohorts of Vg9Vd2-treated and untreated mice reveals that mice receiving Vg9Vd2 T cells displayed superior survival compared with untreated controls (P=0.0047). CONCLUSIOn: Altogether, our data indicate that Vg9Vd2 T cells are decreased in AML patients and have a more limited expansion potential. However, they are able to kill autologous AML blast upon stimulation in a TCRVd2 as well as the DNAM-1 receptor dependent manner. These results provide a rationale for the clinical evaluation of adoptive transfer of ex vivo expanded allogenic Vg9Vd2T cells or direct activation of Vg9Vd2T cells with IL2 + phosphoantigens in patients with AML. Disclosures: No relevant conflicts of interest to declare.

Regulation of Fas/Fas Ligand-Mediated Apoptosis in Megakaryocytes by Nuclear Factor of Activated T Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4023-4023
Author(s):  
Laleh S. Arabanian ◽  
Satu Kyttälä ◽  
Ivonne Habermann ◽  
Gerhard Ehninger ◽  
Alexander Kiani
Keyword(s):  
T Cells ◽  
T Lymphocytes ◽  
Fas Ligand ◽  
Jurkat Cells ◽  
Biological Role ◽  
Regulatory Function ◽  
Nuclear Factor ◽  
Activated T Cells ◽  
In Cells

Abstract Abstract 4023 Poster Board III-959 Bone marrow megakaryocytes are the precursors of peripheral blood platelets and therefore constitute an integral part of primary haemostasis, thrombosis and wound healing. Platelets have also been implicated in the regulation of inflammation and other immune responses, but the role of megakaryocytes in this context is less clear. The calcineurin-dependent transcription factor NFAT (Nuclear Factor of Activated T cells) is a master regulator of cytokine production in T lymphocytes and therefore central for T cell-dependent immune reactions. We have previously shown that NFAT is strongly expressed in megakaryocytes and is required for the transcription of specific megakaryocytic genes. The biological role of NFAT in megakaryocytes, however, is unknown. Here we show that activation of the calcineurin/NFAT pathway in either primary megakaryocytes or CMK megakaryocytic cells forces the cells to go into apoptosis. Cell death in megakaryocytes is induced by treating the cells with the calcium ionophore ionomycin and at least partially suppressed by either the pan-caspase inhibitor zVAD or the calcineurin inhibitor cyclosporin A (CsA). Ionomycin stimulation of megakaryocytes leads to the expression of Fas Ligand (FasL), a pro-apoptotic member of the tumor necrosis factor superfamily. Expression of FasL was detectable as early as six hours after stimulation on the membrane of ionomycin-treated megakaryocytes, was augmented in cells stably overexpressing NFATc2, and was suppressed in cells either pretreated with CsA or expressing the specific peptide inhibitor of NFAT, VIVIT. To investigate the physiological relevance of FasL expression on megakaryocytes, we performed cocultures of megakaryocytes with Fas-expressing T lymphocytes, in which CMK cells were either left unstimulated or prestimulated with ionomycin and then added to Jurkat cells. The presence of ionomycin-stimulated CMK cells, but not of unstimulated cells or cells stimulated in the presence of CsA, significantly induced apoptosis in Jurkat cells. Overexpression of NFATc2 in CMK cells enhanced their potency to induce apoptosis in Jurkat cells, while cells expressing VIVIT were less effective. Apoptosis induction of Jurkat cells by stimulated CMK cells was partially blocked by the presence of either a neutralizing antibody against FasL or an antagonistic antibody to Fas during the coculture period, indicating involvement of the FasL/Fas apoptosis pathway. These results have several implications. First, they represent the first clear evidence for a biological function of the calcineurin/NFAT pathway in megakaryocytes, namely the regulation of Fas/FasL-dependent apoptosis. Second, they underline that the biological role of megakaryocytes is not restricted to the production of proteins and other cellular structures for platelet assembly, but that this population of cells fulfills an independent regulatory function in the context of the surrounding tissue. Our results suggest that this regulatory function may include the induction of Fas/FasL-dependent apoptosis in bystander cells under certain conditions, for example the elimination of activated T cells in inflammatory situations. Disclosures: No relevant conflicts of interest to declare.

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