Peripheral T cells undergoing superantigen-induced apoptosis in vivo express B220 and upregulate Fas and Fas ligand.

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen (SAg) that predominantly interacts with V(beta)8+ T cells. In vivo treatment of mice with SEB leads to an initial increase in the percentage of V(beta)8+ T cells, followed by a decrease in the numbers of these cells, eventually reaching lower levels than those found before treatment with the SAg. This decrease is due to apoptosis of the SEB-responding cells. In the present study, we use the distinct light scattering characteristics of apoptotic cells to characterize T cells that are being deleted in response to SEB in vivo. We show that dying, SEB-reactive T cells express high levels of Fas and Fas ligand (Fas-L), which are implicated in apoptotic cell death. In addition, the B cell marker B220 is upregulated on apoptotic cells. Moreover, we show that the generation of cells with an apoptotic phenotype is severely impaired in response to SEB in functional Fas-L-deficient mutant gld mice, confirming the role of the Fas pathway in SAg mediated peripheral deletion in vivo.

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Induction of Fas (Apo-1, CD95)-Mediated Apoptosis of Activated Lymphocytes by Polyclonal Antithymocyte Globulins

Blood ◽

10.1182/blood.v91.7.2360.2360_2360_2368 ◽

1998 ◽

Vol 91 (7) ◽

pp. 2360-2368 ◽

Cited By ~ 2

Author(s):

Laurent Genestier ◽

Sylvie Fournel ◽

Monique Flacher ◽

Olga Assossou ◽

Jean-Pierre Revillard ◽

...

Keyword(s):

T Cells ◽

Peripheral Blood ◽

Fas Ligand ◽

Mononuclear Cells ◽

Resting Cells ◽

Activated T Cells ◽

Peripheral Blood Mononuclear ◽

Gene And Protein Expression ◽

Fas L ◽

Induced Apoptosis

Polyclonal horse antilymphocyte and rabbit antithymocyte globulins (ATGs) are currently used in severe aplastic anemia and for the treatment of organ allograft acute rejection and graft-versus-host disease. ATG treatment induces a major depletion of peripheral blood lymphocytes, which contributes to its overall immunosuppressive effects. Several mechanisms that may account for lymphocyte lysis were investigated in vitro. At high concentrations (.1 to 1 mg/mL) ATGs activate the human classic complement pathway and induce lysis of both resting and phytohemagglutinin (PHA)-activated peripheral blood mononuclear cells. At low, submitogenic, concentration ATGs induce antibody-dependent cell cytotoxicity of PHA-activated cells, but not resting cells. They also trigger surface Fas (Apo-1, CD95) expression in naive T cells and Fas-ligand gene and protein expression in both naive and primed T cells, resulting in Fas/Fas-L interaction-mediated cell death. ATG-induced apoptosis and Fas-L expression were not observed with an ATG preparation lacking CD2 and CD3 antibodies. Susceptibility to ATG-induced apoptosis was restricted to activated cells, dependent on IL-2, and prevented by Cyclosporin A, FK506, and rapamycin. The data suggest that low doses of ATGs could be clinically evaluated in treatments aiming at the selective deletion of in vivo activated T cells in order to avoid massive lymphocyte depletion and subsequent immunodeficiency.

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A subclass of dendritic cells kills CD4 T cells via Fas/Fas-ligand-induced apoptosis.

Journal of Experimental Medicine ◽

10.1084/jem.183.4.1789 ◽

1996 ◽

Vol 183 (4) ◽

pp. 1789-1796 ◽

Cited By ~ 476

Author(s):

G Süss ◽

K Shortman

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Cd4 T Cells ◽

Fas Ligand ◽

Activated T Cells ◽

T Cell Apoptosis ◽

Peripheral T Cells ◽

Surface Staining ◽

Induced Apoptosis ◽

Antigen Presenting

Dendritic cells (DC), the most efficient antigen-presenting cells, are well equipped for activation of naive CD4+ T cells by their expression of high levels of major histocompatibility complex and costimulator molecules. We now demonstrate that some DC are equally well equipped for killing these same T cells. Murine splenic DC consist of both conventional CD8alpha- DC and a major population of CD8alpha+ DC. Whereas CD8- DC induce a vigorous proliferative response in CD4 T cells, CD8+ DC induce a lesser response that is associated with marked T cell apoptosis. By using various mixtures of T cells and DC from Fas-mutant lpr/lpr mice and Fas-ligand (FasL) mutant gld/gld mice, we show this death is due to interaction of Fas on activated T cells with FasL on CD8+ DC. Furthermore, we show by direct surface staining that CD8+ DC, but not CD8- DC, express FasL at high levels. These findings indicate that FasL+ CD8+ DC are a specialized subgroup of DC with a role in the regulation of the response of primary peripheral T cells.

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Apoptotic Role of Fas/Fas Ligand System in the Regulation of Erythropoiesis

Blood ◽

10.1182/blood.v93.3.796.403k23_796_803 ◽

1999 ◽

Vol 93 (3) ◽

pp. 796-803 ◽

Cited By ~ 9

Author(s):

R. De Maria ◽

U. Testa ◽

L. Luchetti ◽

A. Zeuner ◽

G. Stassi ◽

...

Keyword(s):

Bone Marrow ◽

Fas Ligand ◽

Control Mechanism ◽

Erythroid Differentiation ◽

Dependent Manner ◽

Normal Bone ◽

In Vivo Analysis ◽

Induced Apoptosis

The possible involvement of Fas and Fas ligand (FasL) in the regulation of erythropoiesis was evaluated. Immunohistochemistry of normal bone marrow specimens revealed that several immature erythroblasts undergo apoptosis in vivo. Analysis of bone marrow erythroblasts and purified progenitors undergoing unilineage erythroid differentiation showed that Fas is rapidly upregulated in early erythroblasts and expressed at high levels through terminal maturation. However, Fas crosslinking was effective only in less mature erythroblasts, particularly at basophilic level, where it induced apoptosis antagonized by high levels of erythropoietin (Epo). In contrast, FasL was selectively induced in late differentiating Fas-insensitive erythroblasts, mostly at the orthochromatic stage. FasL is functional in mature erythroblasts, as it was able to kill Fas-sensitive lymphoblast targets in a Fas-dependent manner. Importantly, FasL-bearing mature erythroblasts displayed a Fas-based cytotoxicity against immature erythroblasts, which was abrogated by high levels of Epo. These findings suggest the existence of a negative regulatory feedback between mature and immature erythroid cells, whereby the former cell population might exert a cytotoxic effect on the latter one in the erythroblastic island. Hypothetically, this negative feedback operates at low Epo levels to moderate the erythropoietic rate; however, it is gradually inhibited at increasing Epo concentrations coupled with enhanced erythrocyte production. Thus, the interaction of Fas and FasL may represent an apoptotic control mechanism for erythropoiesis, contributing to the regulation of red blood cell homeostasis.

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Fas/FasL Pathway Participates in Regulation of Antiviral and Inflammatory Response during Mousepox Infection of Lungs

Mediators of Inflammation ◽

10.1155/2015/281613 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 10

Author(s):

Karolina Bień ◽

Justyna Sokołowska ◽

Piotr Bąska ◽

Zuzanna Nowak ◽

Wanda Stankiewicz ◽

...

Keyword(s):

T Cells ◽

Inflammatory Response ◽

Fas Ligand ◽

Antiviral Response ◽

Target Cells ◽

Local Inflammatory Response ◽

Induced Apoptosis ◽

Deficient Mice

Fas receptor-Fas ligand (FasL) signalling is involved in apoptosis of immune cells as well as of the virus infected target cells but increasing evidence accumulates on Fas as a mediator of apoptosis-independent processes such as induction of activating and proinflammatory signals. In this study, we examined the role of Fas/FasL pathway in inflammatory and antiviral response in lungs using a mousepox model applied to C57BL6/J, B6. MRL-Faslpr/J, and B6Smn.C3-Faslgld/J mice. Ectromelia virus (ECTV) infection of Fas- and FasL-deficient mice led to increased virus titers in lungs and decreased migration of IFN-γexpressing NK cells, CD4+ T cells, CD8+ T cells, and decreased IL-15 expression. The lungs of ECTV-infected Fas- and FasL-deficient mice showed significant inflammation during later phases of infection accompanied by decreased expression of anti-inflammatory IL-10 and TGF-β1 cytokines and disturbances in CXCL1 and CXCL9 expression. Experiments in vitro demonstrated that ECTV-infected cultures of epithelial cells, but not macrophages, upregulate Fas and FasL and are susceptible to Fas-induced apoptosis. Our study demonstrates that Fas/FasL pathway during ECTV infection of the lungs plays an important role in controlling local inflammatory response and mounting of antiviral response.

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Characterization of apoptosis-resistant antigen-specific T cells in vivo.

Journal of Experimental Medicine ◽

10.1084/jem.183.5.2065 ◽

1996 ◽

Vol 183 (5) ◽

pp. 2065-2073 ◽

Cited By ~ 45

Author(s):

L Zhang ◽

R G Miller ◽

J Zhang

Keyword(s):

T Cells ◽

Small Population ◽

Peripheral Tolerance ◽

Clonal Deletion ◽

Fas L ◽

Induced Apoptosis ◽

High Level

Clonal deletion via activation-induced apoptosis (AIA) of antigen-specific T cells (ASTC) plays a very important role in the induction of peripheral tolerance. However, none of the studies performed so far has shown a complete deletion of ASTC, a small population always persisting in the periphery. The mechanism by which this small population of ASTC escapes AIA has not been determined. Since the existence of these ASTC may influence the outcome of autoimmune diseases and long-term graft survival, we have characterized the properties of these residual ASTC in vivo with the objective of determining mechanisms that may contribute to their persistence. It was found that the resistance of the residual ASTC to AIA is not due to lack of activation or Fas/Fas-L expression. Compared to those susceptible to AIA, the residual ASTC express a high level of Th2-type cytokines that may help them to escape from AIA. Furthermore, they are able to suppress proliferation of other ASTC, suggesting they may, in fact, prolong tolerance in vivo.

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Induction of Fas (Apo-1, CD95)-Mediated Apoptosis of Activated Lymphocytes by Polyclonal Antithymocyte Globulins

Blood ◽

10.1182/blood.v91.7.2360 ◽

1998 ◽

Vol 91 (7) ◽

pp. 2360-2368 ◽

Cited By ~ 167

Author(s):

Laurent Genestier ◽

Sylvie Fournel ◽

Monique Flacher ◽

Olga Assossou ◽

Jean-Pierre Revillard ◽

...

Keyword(s):

T Cells ◽

Peripheral Blood ◽

Fas Ligand ◽

Mononuclear Cells ◽

Resting Cells ◽

Activated T Cells ◽

Peripheral Blood Mononuclear ◽

Gene And Protein Expression ◽

Fas L ◽

Induced Apoptosis

Abstract Polyclonal horse antilymphocyte and rabbit antithymocyte globulins (ATGs) are currently used in severe aplastic anemia and for the treatment of organ allograft acute rejection and graft-versus-host disease. ATG treatment induces a major depletion of peripheral blood lymphocytes, which contributes to its overall immunosuppressive effects. Several mechanisms that may account for lymphocyte lysis were investigated in vitro. At high concentrations (.1 to 1 mg/mL) ATGs activate the human classic complement pathway and induce lysis of both resting and phytohemagglutinin (PHA)-activated peripheral blood mononuclear cells. At low, submitogenic, concentration ATGs induce antibody-dependent cell cytotoxicity of PHA-activated cells, but not resting cells. They also trigger surface Fas (Apo-1, CD95) expression in naive T cells and Fas-ligand gene and protein expression in both naive and primed T cells, resulting in Fas/Fas-L interaction-mediated cell death. ATG-induced apoptosis and Fas-L expression were not observed with an ATG preparation lacking CD2 and CD3 antibodies. Susceptibility to ATG-induced apoptosis was restricted to activated cells, dependent on IL-2, and prevented by Cyclosporin A, FK506, and rapamycin. The data suggest that low doses of ATGs could be clinically evaluated in treatments aiming at the selective deletion of in vivo activated T cells in order to avoid massive lymphocyte depletion and subsequent immunodeficiency.

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OXPHOS Promotes Apoptotic Resistance and Persistence in TH17 cells

10.1101/2021.10.01.462812 ◽

2021 ◽

Author(s):

Hanna S. Hong ◽

Nneka E. Mbah ◽

Mengrou Shan ◽

Kristen Loesel ◽

Lin Lin ◽

...

Keyword(s):

T Cells ◽

Cell Death ◽

Cell Fate ◽

Apoptotic Cell ◽

Metabolic Phenotype ◽

Tumor Studies ◽

A Cell

AbstractApoptotic cell death is a cell-intrinsic, immune tolerance mechanism that regulates the magnitude and resolution of T cell-mediated responses. Evasion of apoptosis is critical for the generation of memory T cells, as well as autoimmune T cells, and knowledge of the mechanisms that enable resistance to apoptosis will provide insight into ways to modulate their activity during protective and pathogenic responses. IL-17-producing CD4 T cells (TH17s) are long-lived, memory cells. These features enable their role in host defense, chronic inflammatory disorders, and anti-tumor immunity. A growing number of reports now indicate that TH17s in vivo require mitochondrial oxidative phosphorylation (OXPHOS), a metabolic phenotype that is poorly induced in vitro. To elucidate the role of OXPHOS in TH17 processes, we developed a system to polarize TH17s that metabolically resembled their in vivo counterparts. We discovered that directing TH17s to use OXPHOS promotes mitochondrial fitness, glutamine anaplerosis, and an anti-apoptotic phenotype marked by high BCL-XL and low BIM. Through competitive co-transfer experiments and tumor studies, we further revealed how OXPHOS protects TH17s from cell death while enhancing their persistence in the periphery and tumor microenvironment. Together, our work demonstrates a non-classical role of metabolism in regulating TH17 cell fate and highlights the potential for therapies that target OXPHOS in TH17-driven diseases.

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Apoptotic Role of Fas/Fas Ligand System in the Regulation of Erythropoiesis

Blood ◽

10.1182/blood.v93.3.796 ◽

1999 ◽

Vol 93 (3) ◽

pp. 796-803 ◽

Cited By ~ 181

Author(s):

R. De Maria ◽

U. Testa ◽

L. Luchetti ◽

A. Zeuner ◽

G. Stassi ◽

...

Keyword(s):

Bone Marrow ◽

Fas Ligand ◽

Control Mechanism ◽

Erythroid Differentiation ◽

Dependent Manner ◽

Normal Bone ◽

In Vivo Analysis ◽

Induced Apoptosis

Abstract The possible involvement of Fas and Fas ligand (FasL) in the regulation of erythropoiesis was evaluated. Immunohistochemistry of normal bone marrow specimens revealed that several immature erythroblasts undergo apoptosis in vivo. Analysis of bone marrow erythroblasts and purified progenitors undergoing unilineage erythroid differentiation showed that Fas is rapidly upregulated in early erythroblasts and expressed at high levels through terminal maturation. However, Fas crosslinking was effective only in less mature erythroblasts, particularly at basophilic level, where it induced apoptosis antagonized by high levels of erythropoietin (Epo). In contrast, FasL was selectively induced in late differentiating Fas-insensitive erythroblasts, mostly at the orthochromatic stage. FasL is functional in mature erythroblasts, as it was able to kill Fas-sensitive lymphoblast targets in a Fas-dependent manner. Importantly, FasL-bearing mature erythroblasts displayed a Fas-based cytotoxicity against immature erythroblasts, which was abrogated by high levels of Epo. These findings suggest the existence of a negative regulatory feedback between mature and immature erythroid cells, whereby the former cell population might exert a cytotoxic effect on the latter one in the erythroblastic island. Hypothetically, this negative feedback operates at low Epo levels to moderate the erythropoietic rate; however, it is gradually inhibited at increasing Epo concentrations coupled with enhanced erythrocyte production. Thus, the interaction of Fas and FasL may represent an apoptotic control mechanism for erythropoiesis, contributing to the regulation of red blood cell homeostasis.

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P13.17 CD95 gene silencing affects growth and invasiveness of glioma-initiating cells in a CD95L-independent manner

Neuro-Oncology ◽

10.1093/neuonc/noab180.124 ◽

2021 ◽

Vol 23 (Supplement_2) ◽

pp. ii36-ii36

Author(s):

C Quijano-Rubio ◽

M Weller

Keyword(s):

Gene Silencing ◽

Apoptotic Cell ◽

Gene Knockout ◽

Acquired Resistance ◽

Independent Manner ◽

Glioma Initiating Cells ◽

Induced Apoptosis

Abstract BACKGROUND CD95 (Fas/APO-1) holds a dual role of potential relevance in tumor development. CD95-CD95 ligand (CD95L) signaling regulates apoptotic cell death in CD95-expressing cells, but non-apoptotic, tumor-promoting CD95-CD95L signaling has been likewise described. Therapeutic stimulation of apoptotic CD95 signaling is associated with major clinical side effects. However, inhibition of tumor-promoting CD95 signaling may represent a promising treatment strategy for human cancers where potential tumor-promoting CD95 functions include invasiveness and cancer cell stemness, including glioblastoma. MATERIAL AND METHODS In this study, CD95 and CD95L expression was characterized in human glioma-initiating cells (GIC) in vitro and in vivo. CD95 and CD95L gene knockout (KO) GIC were generated by means of CRISPR-Cas9 and the effects of gene silencing were evaluated by assessing growth, clonogenicity, invasiveness and tumorigenicity in nude mice. RESULTS CD95 expression and sensitivity to exogenous CD95L-induced apoptosis were confirmed in selected GIC in vitro. CD95L expression was not detected. Upon CD95 KO, all GIC acquired resistance to CD95L-induced apoptosis. Furthermore, despite the confirmed absence of CD95L expression in vitro, CD95 KO S-24 GIC revealed decreased cell growth, inferior sphere forming capacity and decreased invasiveness. These data suggested a CD95L-independent tumor-promoting role of CD95 in S-24 GIC. In vivo, however, CD95 KO did not prolong the survival of glioma-bearing mice. Analyses of further GIC models are ongoing. CONCLUSION These data demonstrate that, unlike CD95, CD95L is not expressed in cultured human GIC and that CD95-CD95L interactions are not required for tumor-promoting CD95 signaling. Although CD95 KO is detrimental for S-24 GIC in vitro, CD95 KO alone does not affect survival in S-24 human GIC xenograft-bearing mice.

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