T hybridoma αβ gene transfected in a murine T cell hybridoma: Role of CD4 molecule in vitro and in vivo—Engraftment in SCID mice induces T cell maturation

Interleukin-27 (IL-27) is a cytokine known to have both proinflammatory and immunoregulatory functions. The latter appear to dominate in vivo, where IL-27 suppresses TH17 responses and promotes the differentiation of Tr1 cells expressing interferon-γ and IL-10 and lacking forkhead box P3 (Foxp3). Accordingly, IL-27 receptor α (Il27ra)–deficient mice suffer from exacerbated immune pathology when infected with various parasites or challenged with autoantigens. Because the role of IL-27 in human and experimental mouse colitis is controversial, we studied the consequences of Il27ra deletion in the mouse T cell transfer model of colitis and unexpectedly discovered a proinflammatory role of IL-27. Absence of Il27ra on transferred T cells resulted in diminished weight loss and reduced colonic inflammation. A greater fraction of transferred T cells assumed a Foxp3+ phenotype in the absence of Il27ra, suggesting that IL-27 functions to restrain regulatory T cell (Treg) development. Indeed, IL-27 suppressed Foxp3 induction in vitro and in an ovalbumin-dependent tolerization model in vivo. Furthermore, effector cell proliferation and IFN-γ production were reduced in the absence of Il27ra. Collectively, we describe a proinflammatory role of IL-27 in T cell–dependent intestinal inflammation and provide a rationale for targeting this cytokine in pathological situations that result from a breakdown in peripheral immune tolerance.

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Bacterial Pathogens Induce Abscess Formation by CD4+ T-Cell Activation via the CD28–B7-2 Costimulatory Pathway

Infection and Immunity ◽

10.1128/iai.68.12.6650-6655.2000 ◽

2000 ◽

Vol 68 (12) ◽

pp. 6650-6655 ◽

Cited By ~ 37

Author(s):

Arthur O. Tzianabos ◽

Anil Chandraker ◽

Wiltrud Kalka-Moll ◽

Francesca Stingele ◽

Victor M. Dong ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Pathogenic Bacteria ◽

Cell Activation ◽

Bacterial Pathogens ◽

Abscess Formation

ABSTRACT Abscesses are a classic host response to infection by many pathogenic bacteria. The immunopathogenesis of this tissue response to infection has not been fully elucidated. Previous studies have suggested that T cells are involved in the pathologic process, but the role of these cells remains unclear. To delineate the mechanism by which T cells mediate abscess formation associated with intra-abdominal sepsis, the role of T-cell activation and the contribution of antigen-presenting cells via CD28-B7 costimulation were investigated. T cells activated in vitro by zwitterionic bacterial polysaccharides (Zps) known to induce abscess formation required CD28-B7 costimulation and, when adoptively transferred to the peritoneal cavity of naı̈ve rats, promoted abscess formation. Blockade of T-cell activation via the CD28-B7 pathway in animals with CTLA4Ig prevented abscess formation following challenge with different bacterial pathogens, including Staphylococcus aureus,Bacteroides fragilis, and a combination ofEnterococcus faecium and Bacteroides distasonis. In contrast, these animals had an increased abscess rate following in vivo T-cell activation via CD28 signaling. Abscess formation in vivo and T-cell activation in vitro required costimulation by B7-2 but not B7-1. These results demonstrate that abscess formation by pathogenic bacteria is under the control of a common effector mechanism that requires T-cell activation via the CD28–B7-2 pathway.

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Dendritic cell-derived IL-2 production is regulated by IL-15 in humans and in mice

Blood ◽

10.1182/blood-2004-03-1059 ◽

2005 ◽

Vol 105 (2) ◽

pp. 697-702 ◽

Cited By ~ 65

Author(s):

Sonia Feau ◽

Valeria Facchinetti ◽

Francesca Granucci ◽

Stefania Citterio ◽

David Jarrossay ◽

...

Keyword(s):

Dendritic Cells ◽

T Cell ◽

Molecular Mechanisms ◽

Interleukin 2 ◽

Adaptive Immune ◽

Deficient Mice ◽

Mouse System

Abstract Dendritic cells (DCs) are involved in the initiation and regulation of innate and adaptive immune responses. Several molecular mechanisms regulate these diverse DC functions, and we have previously reported that mouse dendritic cells (mDCs) can produce interleukin-2 (IL-2) in vitro and in vivo, in response to microbial activation and T-cell-mediated stimuli. This property is shared by different DC subtypes, including Langerhans cells. Here we show that, on appropriate stimulation, human DCs, both plasmacytoid and myeloid subtypes, also express IL-2. Interestingly, the production of IL-2 by myeloid DCs is induced by T-cell-mediated stimuli and depends on the presence of IL-15. The key role of this cytokine in regulating IL-2 production was also confirmed in the mouse system. In particular, we could show that DCs from IL-15-deficient mice were strongly impaired in the ability to produce IL-2 after interactions with different microbial stimuli. Our results indicate that DC-produced IL-2 is tightly coregulated with the expression of IL-15.

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An in vitro system of T cell maturation-effect of cytokines and of thymic epithelial cells ♦ 865

Pediatric Research ◽

10.1203/00006450-199804001-00886 ◽

1998 ◽

Vol 43 ◽

pp. 150-150

Author(s):

Athena P Kourtis ◽

Francis K Lee ◽

Christian Ibegbu ◽

Edmund Waller ◽

Andre J Nahmias

Keyword(s):

T Cell ◽

Epithelial Cells ◽

Cell Maturation ◽

Thymic Epithelial Cells ◽

In Vitro System ◽

T Cell Maturation

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L-arginine depletion by PEG-arginase I, a new potential therapy for acute lymphoblastic leukemia.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.6580 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. 6580-6580

Author(s):

Ofelia Crombet Ramos ◽

Claudia Hernandez ◽

Kevin Morrow ◽

John T. Cole ◽

Paulo Rodriguez

Keyword(s):

Cell Proliferation ◽

Acute Lymphoblastic Leukemia ◽

T Cell ◽

De Novo ◽

Remission Rate ◽

Lymphoblastic Leukemia ◽

Arginase I

6580 Background: Advances in therapies have resulted in an overall complete remission rate of approximately 85% for childhood acute lymphoblastic leukemia (ALL). In contrast, the overall remission rate of adults with leukemia continues to be poor, only about 40% in cases of T cell-ALL (T-ALL). Therefore, it is imperative to generate new therapies that alone or in combination with other treatments could potentially increase the percentages of complete responders or be used to treat the refractory ALL population. Our published results show that a pegylated form of human arginase I (peg-Arg I) prevented T-ALL cell proliferation in vitro and in vivo through the induction of tumor cell apoptosis. Interestingly, the anti-leukemic effects induced by peg-Arg I did not affect the anti-tumor activity of normal T cells, suggesting an anti-tumor specific effect. Our hypothesis states that peg-Arg I has an anti-tumoral effect on B-ALL and T-ALL cells in vitro and that the sensitivity of ALL cells to peg-Arg I depends on their expression of argininosuccinate synthase (ASS) and their ability to produce L-arginine de novo from citrulline. Methods: Malignant T cell proliferation was tested using nonradioactive cell proliferation yellow tretrazolium salt kit. Apoptosis studies were based on the expression of annexin V. Western blot assays were conducted to determine enzymatic expression in different cell lines. Results: The results of our in vitro experiments showed that peg-Arg I had a pro-apoptotic and anti-proliferattive effect on B-ALL cells similar to the one previously seen on T-ALL cells. These effects can be overcome in cell lines able that express ASS and therefore to produce L-arginine de novo. Conclusions: Our results suggest the role of ASS in the ALL-apoptosis induced by peg-Arg-I. Our next steps include: _Understand why ASS-expressing ALL cells do not undergo apoptosis when cultured with peg-Arg-I_Determine the role of ASS in the anti-leukemic effect induced by peg-Arg-I in vivo. Completion of this research is expected to lead to a better understanding of how peg-Arg-I kills ALL cells and could provide the foundation for a novel therapy for ALL patients.

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Notch Regulation by the Fbw7/hcdc4/Sel-10 Ubiquitin Ligase.

Blood ◽

10.1182/blood.v108.11.1420.1420 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1420-1420

Author(s):

Jonathan E. Grim ◽

Olga Sala ◽

Nack Gyun Chung ◽

Jerald Radich ◽

Barbara J. Varnum-Finney ◽

...

Keyword(s):

T Cell ◽

Ubiquitin Ligase ◽

Heterozygous Mutation ◽

Candidate Peptide ◽

Human T Cell ◽

Notch Protein ◽

Important Regulator

Abstract T-cell neoplasms frequently sustain mutations in the Notch1 gene, leading to the expression of constitutively active Notch proteins. Such mutations often target the C-terminal PEST domain, which is known to be involved in protein stability. The ubiquitin ligase Fbw7/hdcd4/Sel-10 is a tumor suppressor that negatively regulates Notch function by targeting the Notch protein for ubiquitination and proteasomal degradation. Although the PEST domain is known to be important for Fbw7/Notch interactions, the specific residues that regulate binding of Notch to Fbw7 have not been defined. Based on the structural motifs (known as phosphodegrons) common to known substrates of Fbw7, we have identified two candidate peptide sequences within the Notch protein and have generated a series of mutants in these regions. Using co-immunoprecipitation assays, we show that one potential phosphodegron that is outside of the PEST domain does not appear to influence Notch binding to Fbw7. However, a second potential phosphodegron is present within the PEST domain and contains a conserved threonine residue (T2512) which is central to binding of Fbw7 to Notch. A mutant in which this residue is replaced by alanine (T2512A) shows a prolonged half life when compared to wild type Notch ICD, supporting its role in Notch stability. To evaluate the role of Fbw7 mediated Notch degradation in vitro and in vivo, we used lentiviral vectors to transfect hematopoietic cells with shRNA targeting Fbw7. These studies demonstrate that Fbw7 knockdown leads to phenotypes consistent with increased Notch activity. Because Notch is commonly mutated in human leukemias, we hypothesized that Fbw7 may also sustain mutations that lead to loss of Notch regulation. We evaluated primary human T cell leukemias for mutations in Fbw7 and found that 1 of 23 samples contains a heterozygous mutation in the Fbw7 common region (R505C). We show that this mutant is deficient in binding to Notch, suggesting that Fbw7 mutation may contribute to the deregulation of Notch that is commonly seen in T-cell neoplasms. Together, this work shows that Fbw7 is an important regulator of Notch function whose mutation may be an important step in leukemogenesis.

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