Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of FasL

  • soluble fasl

  • Terms modified by FasL

  • fasl expression

  • Selected Abstracts

    Expression of FasL in squamous cell carcinomas of the cervix and cervical intraepithelial neoplasia and its role in tumor escape mechanism,

    CANCER, Issue 5 2006
    Ramy Ibrahim M.D.
    Abstract BACKGROUND To date, several mechanisms have been described by which malignant cells escape from the immune system. One of these is through the expression of FasL. The authors hypothesized that the Fas/FasL interaction enables cervical carcinoma cells to induce apoptosis of the cells of the immune system and thereby escape from them. METHODS The authors tested the expression of FASL on the surface of cervical carcinoma tissues. Next, they stained the same cervical tissues with anti-human leukocyte common antigen and TUNEL to identify apoptotic cells. An in vitro functional assay was then done to test if the FASL expressed on the surface of cervical carcinoma cell lines was or was not responsible for inducing apoptosis in T-cells. Finally, they compared the expression of FASL on normal and dysplastic cervical tissues. RESULTS Ninety-four percent of the cervical carcinoma tissues the authors tested expressed FasL and the majority of the apoptotic cells in the specimens were leukocytes with very few tumor cells. In the in vitro functional assay, only the Fasl expressing cell line and not the Fasl negative cell line was able to induce apoptosis of the Fas-expressing Jurkat cells. On examining the normal cervical tissues, the authors found that the expression of Fasl was confined to the basal cell layer with loss of expression observed in the suprabasal layers, which made it an immune privileged site. Conversely, there was persistent expression of FasL in the dysplastic layers in cervical dysplasia and squamous cell carcinoma specimens. CONCLUSIONS The findings of the current study support the authors' hypothesis that persistent expression of FasL plays a role in the ability of cervical carcinoma cells to escape from the immune system. Cancer 2006. Published 2006 by the American Cancer Society. [source]

    Fas and Fas ligand expression on germinal center type-diffuse large B-cell lymphoma is associated with the clinical outcome

    Yasushi Kojima
    Abstract:, In recent years, diffuse large B-cell lymphoma (DLBCL) has been classified by DNA microarray analysis into the germinal center B-cell-like (GC) type, the activated B-cell-like (ABC) type and type 3. The latter two types can be collectively categorized as the non-GC (NGC) type. From the prognostic perspective, the GC type has a favorable clinical outcome when compared with the NGC type. The protein Fas induces apoptosis of lymphocytes by binding with the Fas ligand (FasL), and escape from such apoptosis is considered to lead to malignant transformation of the cells and unrestricted growth of lymphoma. We proposed a hypothesis that Fas/FasL expression could be possibly related with a better survival of GC type DLBCL and evaluated 69 DLBCL cases immunohistochemically with CD10, Bcl-6, MUM1, Fas and FasL. These lymphomas were classified as GC type (positive for CD10 or Bcl-6 and negative for MUM1) or NGC type. The GC type had a better overall survival rate than the NGC type (P = 0.0723). Among markers as given above, positive CD10 was the most significant prognostic factor for overall survival in total DLBCL (P < 0.05). In the GC type, Fas and FasL expressions were significantly associated with a favorable overall survival (Fas: P < 0.005; FasL: P < 0.05). Hence, Fas or FasL expression might contribute to a better prognosis of this type of DLBCL. [source]

    The role of Fas ligand as an effector molecule in corneal graft rejection

    Abstract Previous studies have shown that the expression of Fas ligand (FasL; CD95L) by donor corneas is critical to their survival when placed on allogeneic recipients. Since there have been reports that the cornea expresses Fas, we tested the idea that FasL on lymphoid cells could be an effector molecule during rejection episodes. When FasL defective BALB/c- gld mice were engrafted with allogeneic corneas, significantly more of these corneas were accepted than by normal BALB/c mice. However, this was not due to impaired FasL-mediated effector function in these mice as the allogeneic corneas did not express detectable Fas by Western blot or RT-PCR analysis. Furthermore, donor corneas without Fas were given no survival advantage, but were rejected similar to wild-type donor allogeneic corneas. Examination of the T cell compartment in gld mice revealed that these cells express higher levels of Fas and are more susceptible to Fas-mediated death than wild-type cells. These results indicate that FasL is not an effector molecule in corneal graft rejection and that gld mice show reduced graft rejection due to greater susceptibility of their T cells to Fas-mediated apoptosis. [source]

    Involvement of mitochondrial signaling pathways in the mechanism of Fas-mediated apoptosis after spinal cord injury

    Wen Ru Yu
    Abstract Activation of the Fas receptor has been recently linked to apoptotic cell death after spinal cord injury (SCI). Although it is generally considered that Fas activation mediates apoptosis predominantly through the extrinsic pathway, we hypothesized that intrinsic mitochondrial signaling could be involved in the underlying mechanism of Fas-induced apoptosis after SCI. In the present study, we utilized the FejotaTM clip compression model of SCI at T5,6 in C57BL/6 Fas-deficient (lpr) and wild-type mice. Complementary studies were conducted using an in vitro model of trauma or a Fas-activating antibody to induce apoptosis in primary neuronal,glial mixed spinal cord cultures. After in vivo SCI, lpr mice, in comparison with wild-type mice, exhibited reduced numbers of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells at the lesion, reduced expression of truncation of Bid (tBid), apoptosis-inducing factor, activated caspase-9 and activated caspase-3, and increased expression of the antiapoptotic proteins Bcl-2 and Bcl-xL. After in vitro neurotrauma or the induction of Fas signaling by the Jo2 activating antibody, lpr spinal cord cultures showed an increased proportion of cells retaining mitochondrial membrane integrity and a reduction of tBid expression, caspase-9 and caspase-3 activation, and TUNEL-positive cells as compared to wild-type spinal cord cultures. The neutralization of Fas ligand (FasL) protected against traumatically induced or Fas-mediated caspase-3 activation and the loss of mitochondrial membrane potential and tBid expression in wild-type spinal cord cultures. However, in lpr spinal cord cultures, FasL neutralization had no protective effects. In summary, these data provide direct evidence for the induction of intrinsic mitochondrial signaling pathways following Fas activation after SCI. [source]

    Apoptosis in oral lichen planus

    Evelyn Neppelberg
    Apoptotic cell death may be a contributory cause of basal cell destruction in oral lichen planus (OLP). Therefore, the purpose of this study was to investigate the rate of apoptosis in OLP and the expression of two proteins (FasR and FasL) regulating this process. Biopsies from 18 patients with histologically diagnosed OLP were investigated, with comparison to normal oral mucosa of healthy persons. For visualisation of DNA fragmentation, the TUNEL method was used. In order to characterise the infiltrating cell population (CD3, CD4, CD8) and expression of FasR and FasL, we used an immunohistochemical technique. The results showed that T cells dominated in the subepithelial cell infiltrate. Within the epithelium the apoptotic cells were confined to the basal cell layer, and more apoptotic cells were seen in areas with basal cell degeneration and atrophic epithelium. There was a prominent expression of FasR/FasL in OLP, with a rather uniform distribution throughout the inflammatory cell infiltrate. In the epithelium, the FasR/FasL expression was more abundant in the basal cell area compared to the suprabasal cell layer. In conclusion, apoptosis within the epithelium is significantly increased in situ in OLP compared to normal oral mucosa, and seems to be related to the epithelial thickness. [source]

    In vivo UVB irradiation induces clustering of Fas (CD95) on human epidermal cells

    Bo Bang
    Abstract:,In vitro studies with human cell lines have demonstrated that the death receptor Fas plays a role in ultraviolet (UV)-induced apoptosis. The purpose of the present study was to investigate the relation between Fas expression and apoptosis as well as clustering of Fas in human epidermis after a single dose of UVB irradiation. Normal healthy individuals were irradiated with three minimal erythema doses (MED) of UVB on forearm or buttock skin. Suction blisters from unirradiated and irradiated skin were raised, and Fas, FasL, and apoptosis of epidermal cells were quantified by flow cytometry. Clustering of Fas was demonstrated by confocal laser scanning microscopy on cryostat sections from skin biopsies. Soluble FasL in suction blister fluid was quantified by ELISA. Flow cytometric analysis demonstrated increased expression intensity of Fas after irradiation, with 1.6-, 2.2- and 2.7-fold increased median expression at 24, 48 and 72 h after irradiation, respectively (n = 4). Apoptosis was demonstrated by the TUNEL reaction, and the maximum of apoptotic cells was detected at 48 h after irradiation. Double-staining for Fas and TUNEL showed that apoptosis was restricted to the Fas-positive epidermal subpopulation, but there was no correlation between the intensities of Fas expression and TUNEL reaction. Median expression intensity of FasL-positive cells transiently decreased to 0.9- and 0.8-fold of the preirradiation respective level after 24 h and 48 h, respectively, and returned to the respective preirradiation level at 72 h after irradiation (n = 4). Concentrations of soluble FasL in suction blister fluid from UVB-irradiated skin did not differ from those in unirradiated skin (n = 5). Confocal laser scanning microscopy showed a rapid clustering of Fas within 30 min after irradiation. A simultaneous clustering of the adapter signalling protein FADD suggested that Fas clustering has a functional significance. Our results are in accordance with previous findings from in vitro studies, and suggest that Fas is activated in vivo in human epidermis after UVB exposure. [source]

    Caspase-8- and JNK-dependent AP-1 activation is required for Fas ligand-induced IL-8 production

    FEBS JOURNAL, Issue 9 2007
    Norihiko Matsumoto
    Despite a dogma that apoptosis does not induce inflammation, Fas ligand (FasL), a well-known death factor, possesses pro-inflammatory activity. For example, FasL induces nuclear factor ,B (NF-,B) activity and interleukin 8 (IL-8) production by engagement of Fas in human cells. Here, we found that a dominant negative mutant of c-Jun, a component of the activator protein-1 (AP-1) transcription factor, inhibits FasL-induced AP-1 activity and IL-8 production in HEK293 cells. Selective inhibition of AP-1 did not affect NF-,B activation and vice versa, indicating that their activations were not sequential events. The FasL-induced AP-1 activation could be inhibited by deleting or introducing the lymphoproliferation (lpr) -type point mutation into the Fas death domain (DD), knocking down the Fas-associated DD protein (FADD), abrogating caspase-8 expression with small interfering RNAs, or using inhibitors for pan-caspase and caspase-8 but not caspase-1 or caspase-3. Furthermore, wildtype, but not a catalytically inactive mutant, of caspase-8 reconstituted the FasL-induced AP-1 activation in caspase-8-deficient cells. Fas ligand induced the phosphorylation of two of the three major mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) but not p38 MAPK. Unexpectedly, an inhibitor for JNK but not for MAPK/ERK kinase inhibited the FasL-induced AP-1 activation and IL-8 production. These results demonstrate that FasL-induced AP-1 activation is required for optimal IL-8 production, and this process is mediated by FADD, caspase-8, and JNK. [source]

    Effect of H. pylori on the Expression of TRAIL, FasL and their Receptor Subtypes in Human Gastric Epithelial Cells and their Role in Apoptosis

    HELICOBACTER, Issue 5 2004
    Jan Hendrik Martin
    ABSTRACT Background and Aims., In the human stomach expression of TNF-related apoptosis inducing ligand (TRAIL) and its receptors and the modulatory role of Helicobacter pylori are not well described. Therefore, we investigated the effect of H. pylori on the expression of TRAIL, FasL and their receptors (TRAIL-R1-R4, Fas) in gastric epithelial cells and examined their role in apoptosis. Materials and Methods., mRNA and protein expression of TRAIL, FasL and their receptors were analyzed in human gastric epithelial cells using RT-PCR, Western blot, and immunohistochemistry. Gastric epithelial cells were incubated with FasL, TRAIL and/or H. pylori, and effects on expression, cell viability and epithelial apoptosis were monitored. Apoptosis was analyzed by histone ELISA, DAPI staining and immunohistochemistry. Results., TRAIL, FasL and their receptor subtypes were expressed in human gastric mucosa, gastric epithelial cell primary cultures and gastric cancer cells. TRAIL, FasL and H. pylori caused a time- and concentration-dependent induction of DNA fragmentation in gastric cancer cells with synergistic effects. In addition, H. pylori caused a selective up-regulation of TRAIL, TRAIL-R1 and Fas mRNA and protein expression in gastric cancer cells. Conclusions., Next to FasL and Fas, TRAIL and all of its receptor subtypes are expressed in the human stomach and differentially modulated by H. pylori. TRAIL, FasL and H. pylori show complex interaction mediating apoptosis in human gastric epithelial cells. These findings might be important for the understanding of gastric epithelial cell kinetics in patients with H. pylori infection. [source]

    Functional alterations of liver innate immunity of mice with aging in response to CpG-oligodeoxynucleotide,

    HEPATOLOGY, Issue 5 2008
    Toshinobu Kawabata
    Immune functions of liver natural killer T (NKT) cells induced by the synthetic ligand ,-galactosylceramide enhanced age-dependently; hepatic injury and multiorgan dysfunction syndrome (MODS) induced by ligand-activated NKT cells were also enhanced. This study investigated how aging affects liver innate immunity after common bacteria DNA stimulation. Young (6 weeks) and old (50-60 weeks) C57BL/6 mice were injected with CpG oligodeoxynucleotides (CpG-ODN), and the functions of liver leukocytes were assessed. A CpG-ODN injection into the old mice remarkably increased tumor necrosis factor (TNF) production in Kupffer cells, and MODS and lethal shock were induced, both of which are rarely seen in young mice. Old Kupffer cells showed increased Toll-like receptor-9 expression, and CpG-ODN challenge augmented TNF receptor and Fas-L expression in liver NKT cells. Experiments using mice depleted of natural killer (NK) cells by anti-asialoGM1 antibody (Ab), perforin knockout mice, and mice pretreated with neutralizing interferon (IFN)-, Ab demonstrated the important role of liver NK cells in antitumor immunity. The production capacities of old mice for IFN-,, IFN-,, and perforin were much lower than those of young mice, and the CpG-induced antitumor cytotoxicity of liver NK cells lessened. Lethal shock and MODS greatly decreased in old mice depleted/deficient in TNF, FasL, or NKT cells. However, depletion of NK cells also decreased serum TNF levels and FasL expression of NKT cells, which resulted in improved hepatic injury and survival, suggesting that NK cells are indirectly involved in MODS/lethal shock induced by NKT cells. Neutralization of TNF did not reduce the CpG-induced antitumor effect in the liver. Conclusion: Hepatic injury and MODS mediated by NKT cells via the TNF and FasL-mediated pathway after CpG injection increased, but the antitumor activity of liver NK cells decreased with aging. (HEPATOLOGY 2008.) [source]

    Hepatocytes as cytotoxic effector cells can induce cell death by CD95 ligand-mediated pathway,

    HEPATOLOGY, Issue 6 2006
    Clifford S. Guy
    The liver plays an increasingly recognized role in the host's immune responses. The direct contribution of hepatocytes as effector cells to local immunity, pathogen containment, and liver disease is not determined. This in vitro study examined whether hepatocytes can eliminate other cells via a CD95 ligand (CD95L or FasL)/CD95 (Fas),mediated mechanism and whether this cytotoxic activity can be modulated by cytokines such as interferon gamma (IFN-,) or tumor necrosis factor alpha (TNF-,). We have found that normal woodchuck and human hepatocytes, both cultured and primary freshly isolated, as well as human HepG2 cells, intrinsically transcribe not only CD95 but also CD95L when examined by reverse transcription-polymerase chain reaction (RT-PCR) assays. The functional competence of CD95L, which was detectable in hepatocytes and HepG2 cells by Western blotting, was confirmed in bioassays by induction of apoptosis of CD95-bearing P815 and LS102.9 cell targets and validated by inhibition of the cell killing with CD95 antagonistic antibody or with a general caspase inhibitor. Furthermore, exposure of cultured hepatocytes to IFN-, or their stable transfection with IFN-, cDNA or TNF-, cDNA increased hepatocyte CD95L/CD95,mediated cell killing. In conclusion, hepatocytes express both CD95L and CD95 and they can induce death of other cells by a CD95L-dependent mechanism. IFN-, and, to a lesser extent, TNF-, can enhance hepatocyte CD95L-mediated cytotoxicity. This suggests that the local cytokine environment may modulate the hepatocyte contribution to liver immunity. (HEPATOLOGY 2006;43:1231,1240.) [source]

    Inflammation and drug hepatotoxicity: Aggravation of injury or clean-up mission?,

    HEPATOLOGY, Issue 5 2005
    Hartmut Jaeschke
    BACKGROUND & AIMS Inflammatory mediators released by nonparenchymal inflammatory cells in the liver have been implicated in the progression of acetaminophen (APAP) hepatotoxicity. Among hepatic nonparenchymal inflammatory cells, we examined the role of the abundant natural killer (NK) cells and NK cells with T-cell receptors (NKT cells) in APAP-induced liver injury. METHODS C57BL/6 mice were administered a toxic dose of APAP intraperitoneally to cause liver injury with or without depletion of NK and NKT cells by anti-NK1.1 monoclonal antibody (MAb). Serum alanine transaminase (ALT) levels, liver histology, hepatic leukocyte accumulation, and cytokine/chemokine expression were assessed. RESULTS Compared with APAP-treated control mice, depletion of both NK and NKT cells by anti-NK1.1 significantly protected mice from APAP-induced liver injury, as evidenced by decreased serum ALT level, improved survival of mice, decreased hepatic necrosis, inhibition of messenger RNA (mRNA) expression for interferon-gamma (IFN-gamma), Fas ligand (FasL), and chemokines including KC (Keratinocyte-derived chemokine); MIP-1 alpha (macrophage inflammatory protein-1 alpha); MCP-1 (monocyte chemoattractant protein-1); IP-10 (interferon-inducible protein); Mig (monokine induced by IFN-gamma) and decreased neutrophil accumulation in the liver. Hepatic NK and NKT cells were identified as the major source of IFN-gamma by intracellular cytokine staining. APAP induced much less liver injury in Fas-deficient (lpr) and FasL-deficient (gld) mice compared with that in wild-type mice. CONCLUSIONS NK and NKT cells play a critical role in the progression of APAP-induced liver injury by secreting IFN-gamma, modulating chemokine production and accumulation of neutrophils, and up-regulating FasL expression in the liver, all of which may promote the inflammatory response of liver innate immune system, thus contributing to the severity and progression of liver injury downstream of the metabolism of APAP and depletion of reduced glutathione (GSH) in hepatocytes. [source]

    CD8+ T-cell interaction with HCV replicon cells: Evidence for both cytokine- and cell-mediated antiviral activity

    HEPATOLOGY, Issue 6 2003
    Chen Liu
    The interaction between the host immune response and infected hepatocytes plays a central role in the pathogenesis of hepatitis C virus (HCV). The lack of a suitable animal or in vitro model has hindered our understanding of the host T-cell/HCV interaction. Our aim was to develop an in vitro model to study the mechanisms of HCV-specific T-cell-mediated antiviral and cytolytic function. The HCV replicon was HLA typed and lymphocytes were obtained from an HLA class I-matched subject. CD8+ T cells were expanded with 2 HCV-specific/HLA-restricted peptides for NS3. Lymphocyte preparations were cocultured with HCV replicon (FCA1) and control (Huh7) cells labeled with 51Cr. After a 48-hour incubation, the cells were harvested for RNA extraction. Standard blocking assays were performed in the presence of anti-interferon gamma (IFN-,), anti-tumor necrosis factor , (TNF-,), and anti-FasL. Cytolytic activity was measured by 51Cr release. HCV replicon cells express homozygous HLA-A11 alleles and present HCV nonstructural proteins. HCV-specific expansion of CD8+ cells led to a 10-fold decrease in HCV replication by Northern blot analysis and 21% specific lysis of FCA1 cells (compared with 2% of control Huh7 cells). Twenty percent of this antiviral activity was independent of T-cell binding, suggesting cytokine-mediated antiviral activity. The CD8+ antiviral effect was markedly reduced by blocking either IFN-, or FasL but was unaffected by blocking TNF-,. In conclusion, HCV-specific CD8+ cells inhibit viral RNA replication by cytokine-mediated and direct cytolytic effects. This T-cell/HCV subgenomic replicon system represents a model for the investigation of CD8 cell interaction with HCV-infected hepatocytes. [source]

    Mechanisms of cell death induced by suicide genes encoding purine nucleoside phosphorylase and thymidine kinase in human hepatocellular carcinoma cells in vitro

    HEPATOLOGY, Issue 3 2001
    Tim U. Krohne
    For gene therapy of hepatocellular carcinoma (HCC), the Escherichia coli purine nucleoside phosphorylase (PNP)/fludarabine suicide gene system may be more useful than the herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system as a result of a stronger bystander effect. To analyze the molecular mechanisms involved in PNP/fludarabine-mediated cell death in human HCC cells in comparison with HSV-tk/GCV, we transduced human HCC cells of the cell lines, HepG2 and Hep3B, with PNP or HSV-tk using adenoviral vectors, followed by prodrug incubation. Both systems predominantly induced apoptosis in HepG2 and Hep3B cells. PNP/fludarabine induced strong p53 accumulation and a more rapid onset of apoptosis in p53-positive HepG2 cells as compared with p53-negative Hep3B cells, but efficiency of tumor cell killing was similar in both cell lines. In contrast, HSV-tk/GCV,induced apoptosis was reduced in p53-negative Hep3B cells as compared with p53-positive HepG2 cells. HSV-tk/GCV, but not PNP/fludarabine, caused up-regulation of Fas in p53-positive HepG2 cells and of Fas ligand (FasL) in both HCC cell lines. These results demonstrate cell line,specific differences in response to treatment with PNP/fludarabine and HSV-tk/GCV, respectively, and indicate that PNP/fludarabine may be superior to HSV-tk/GCV for the treatment of human HCC because of its independence from p53 and the Fas/FasL system. (HEPATOLOGY 2001;34:511-518.) [source]

    c-FLIP expression in colorectal carcinomas: association with Fas/FasL expression and prognostic implications

    HISTOPATHOLOGY, Issue 2 2007
    P Korkolopoulou
    Aims:, Disruption of apoptotic cell death has been implicated in tumour aggressiveness in colonic carcinogenesis. The Fas,Fas ligand (FasL) system is involved in the execution of apoptosis induced by the immune system. c-FLIP protein constitutes an inhibitor of Fas and other (TRAIL) death receptor-mediated apoptosis. The aim of this study was to investigate the simultaneous expression of Fas, FasL and c-FLIP in relation to standard clinicopathological parameters and patients' outcome in colorectal cancer. Methods and results:, Levels of Fas, FasL and c-FLIP protein expression were quantified immunohistochemically in paraffin-embedded tissues from 90 patients. Immunopositivity was detected for Fas, FasL and c-FLIP in 71%, 35.5% and 68.8% of cases, respectively. Concurrent expression of Fas/FasL was seen in 28 samples (31%), of which 24 (85.7%) also displayed c-FLIP positivity (P = 0.04). c-FLIP overexpression (> 10%) tended to prevail marginally in higher stage tumours (P = 0.09). Additionally, FasL and c-FLIP adversely affected survival on both univariate (P = 0.001 and P = 0.0024, respectively) and multivariate analysis [hazard ratio (HR) 3.491, P = 0.005 and HR 2.960, P = 0.036, respectively]. Conclusions:, The frequent expression and coexpression of Fas, FasL and c-FLIP in colorectal carcinoma implicates c-FLIP as an inhibitor of the Fas,FasL-induced death pathway in these tumours. Moreover, c-FLIP conveys independent prognostic information in the presence of classical prognosticators. [source]

    Gene expression characteristics of CD28null memory phenotype CD8+ T cells and its implication in T-cell aging

    Monchou Fann
    Summary:, Accumulation of CD28nullCD8+ T cells is considered as one of the hallmarks of aging in the human immune system. However, the precise changes of CD28nullCD8+ T cells, compared to those of the precursor CD28+CD8+ memory T cells, have not been determined. In this study, we present an analysis of the global gene expression profiles of CD28+ and CD28null memory phenotype CD8+ T cells. These two CD8+ T subsets exhibited an overall similar gene expression profile with only a few dozen genes that were differentially expressed. A wide range of functions, including co-stimulation, effector activity, signaling, and transcription, were possessed by these differentially expressed genes, reflecting significant functional changes of CD28null memory phenotype CD8+ T cells from their CD28+ counterparts. In addition, CD28null memory CD8+ T cells expressed several natural killer cell receptors and high levels of granzymes, perforin, and FasL, indicating an increasing capacity for cytotoxicity during memory CD8+ T-cell aging. Interestingly, in vitro culture of these two subsets with interleukin-15 showed that similar gene expression changes occurred in both subsets. Our analysis provides the gene expression portraits of CD28null memory phenotype CD8+ T cells and alteration from their CD28+ counterparts and suggests potential mechanisms of T-cell aging. [source]

    Roles of proinflammatory cytokines and the Fas/Fas ligand interaction in the pathogenesis of inflammatory myopathies

    IMMUNOLOGY, Issue 1pt2 2009
    Masahiro Kondo
    Summary Within the lesions of inflammatory myopathies, muscle fibres and invading mononuclear cells express Fas and Fas ligand (FasL), respectively. However, the roles of the Fas/FasL interaction in the pathogenesis of inflammatory myopathies are not fully understood. In the present study, we investigated the roles of proinflammatory cytokines and the Fas/FasL system in the pathogenesis of inflammatory myopathies. In vitro culturing of muscle cells with the proinflammatory cytokines interferon-,, tumour necrosis factor-,, and interleukin (IL)-1, synergistically increased Fas expression, susceptibility to Fas-mediated apoptosis, and the expression of cytoplasmic caspases 8 and 3. In addition, culturing of muscle cells with activated CD4+ T cells induced muscle cell apoptosis, which was partially inhibited by anti-FasL antibody. We also tested the possibility that T helper (Th) 17, which is an IL-17-producing helper T-cell subset that plays crucial roles in autoimmune and inflammatory responses, participates in the pathogenesis of inflammatory myopathies. Interestingly, in vitro culturing of dendritic cells with anti-Fas immunoglobulin M (IgM) or activated CD4+ T cells induced the expression of mRNA for IL-23p19, but not for IL-12p35, in addition to proinflammatory cytokines. Furthermore, IL-23p19 and IL-17 mRNAs were detected in the majority of biopsy samples from patients with inflammatory myopathies. Taken together, these results suggest that proinflammatory cytokines enhance Fas-mediated apoptosis of muscle cells, and that the Fas/FasL interaction between invading dendritic cells and CD4+ T cells induces local production of IL-23 and proinflammatory cytokines, which can promote the proliferation of Th17 cells and enhance Fas-mediated apoptosis of muscle cells, respectively. [source]

    Fas ligand-induced murine pulmonary inflammation is reduced by a stable decoy receptor 3 analogue

    IMMUNOLOGY, Issue 2 2003
    Mark A. Wortinger
    Summary Fas ligand (FasL)-induced lung inflammation has recently been suggested to play an important role in the pathogenesis of acute respiratory disease syndrome (ARDS). In order to further explore this connection, we established a FasL-induced murine model of pulmonary inflammation. Instillation of recombinant FasL (rFasL) into the lung induced neutrophil infiltration and increased pulmonary permeability, as evidenced by increased total protein in the airspace; both occur in patients with ARDS. These effects were accompanied with a rapid induction of proinflammatory mediators: cytokine granulocyte,macrophage colony-stimulating factor (GM-CSF) and the chemokines macrophage inflammatory protein-2 (MIP-2) and KC. Pretreatment with a FasL antagonist, a decoy receptor 3 analogue (DcR3 analogue), reduced neutrophil infiltration into the airspace and resulted in a highly significant reduction in the levels of GM-CSF, MIP-2 and KC in bronchoalveolar lavage (BAL) fluid. We postulate that rFasL may be responsible for induction of proinflammatory chemokines and cytokines in the lung, which in turn attract neutrophil infiltration into the airspace. This proinflammatory process and the associated pulmonary permeability may, in part, explain the association of FasL with severe pulmonary inflammation, such as ARDS, and shed new light on FasL and its role in lung injury. [source]

    Life and death within germinal centres: a double-edged sword

    IMMUNOLOGY, Issue 2 2002
    Liliana Guzman-Rojas
    Summary Within germinal centres, B lymphocytes are destined to die by apoptosis via Fas signalling, unless they are positively rescued by antigen and by signals initiated by CD40,CD154 interactions. Thus, while the germinal centre microenvironment can become a virtual graveyard for most B lymphocytes that fail to bind antigen with high affinity, it concomitantly provides the necessary stimuli for the survival of cells that successfully accomplish affinity maturation. Such dichotomy in the physiology of germinal centre reaction that results in survival of the functional B-cell repertoire and the elimination of abnormal cells, dictates the fate towards B-cell homeostasis or disease. Consequently, the death and survival-signalling arms within germinal centres predominantly reside on the timely and controlled expression of Fas and its ligand (FasL), and CD40 and CD154, respectively. In keeping with this notion, lymphoproliferation or deficient immunity are documented landmarks of inactivation of either the Fas/FasL or CD40/CD154 signalling pathways. The present review considers two different scenarios in the control of B-cell survival and death within germinal centres. The first is an idealistic scenario, in which a discriminatory and co-ordinate signalling initiated by the CD40/CD154 and Fas/FasL pairs, respectively, leads the rescue of the functional B-cell repertoire and the elimination of the abnormal phenotype. The second is a gloomy scenario in which both the lack and the hyperexpression of either receptor/ligand pairs, are seen as equally deleterious. [source]

    Expression of Fas and Fas ligand in human testicular germ cell tumours

    E. Baldini
    Summary In the present study, we analysed the expression of Fas ligand (FasL) and its cognate receptor Fas in 14 seminomatous testicular germ cell tumours (TGCT) and six normal testicular tissues obtained following orchiectomy. Tissue samples have been processed to prepare either total RNA or protein extracts or fixed and embedded in paraffin for immunohistochemistry (IHC) experiments. Quantitative RT-PCR experiments demonstrated in TGCT a significant (p < 0.01) increase of the FasL mRNA expression of 21.1 ± 5.4 fold, with respect to normal tissues. On the contrary, in the same cancer tissues, the levels of Fas mRNA were significantly (p < 0.01) reduced to 0.27 ± 0.06 fold. These observations were confirmed in western blot experiments showing a significant increase of FasL and a concomitant decrease of Fas proteins in testicular cancer tissues, with respect to normal testis. Moreover, IHC experiments showed a strong FasL immuno-reactivity in six out of eight TGCT samples analysed, while Fas immuno-positivity was found in cancer cells of only two TGCT tissues. In addition, in all tumour samples, infiltrating lymphocytes were Fas positive. However, no correlation could be observed between Fas or FasL mRNA variations and clinical parameters such as patient's age, TNM stage or tumour size. We also compared the serum levels of soluble FasL (sFasL) of 15 patients affected by seminomatous TGCT, of four patients with non-seminomatous TGCT and six age-matched healthy males. No significant differences in sFasL serum level could be identified. In conclusion, our data demonstrated that the majority of seminomas are characterized by an increased expression of FasL and a concomitant reduction of Fas, with respect to human normal testis, and that sFasL serum level is not a tumour marker for patients affected by TGCT. [source]

    CD95L mediates tumor counterattack in vitro but induces neutrophil-independent tumor rejection in vivo

    Frederik H. Igney
    Abstract Many tumors express CD95L (CD178, FasL, APO-1L) and may thus kill tumor-infiltrating lymphocytes, a phenomenon called tumor counterattack. However, presently it is not clear whether tumor counterattack is a relevant immune escape mechanism. To characterize the effect of CD95L expression of tumor cells on tumor-specific T cells, we established an in vitro system with TCR tg T cells and a model tumor antigen. Preactivated antitumor T cells were able to kill CD95L, and CD95L+ tumor cells. CD95L+ tumor cells killed activated T cells in vitro and inhibited the expansion of cytotoxic antitumor T cells in mixed lymphocyte tumor reactions. In vivo CD95L expression led to delayed tumor growth or complete tumor rejection. Neutrophils were not responsible for the delayed growth of the CD95L+ tumors tested. In mice with neutrophils deficient for important cytotoxicity mechanisms (p47phox,/, or iNOS,/, mice), CD95L+ tumors grew similarly as in wild-type mice. Incidence and growth rate of CD95L+ tumors in mice injected with a neutrophil-depleting or an isotype control antibody was the same. In CD95-deficient lpr mice, tumor growth was not altered as compared to wild-type mice. Taken together, CD95L mediated tumor counterattack in vitro, but led to neutrophil-independent tumor rejection in vivo. [source]

    IL-12 receptor-mediated upregulation of FasL in human ovarian carcinoma cells

    Elieser Gorelik
    Abstract The expression and functions of IL-12 receptor (IL-12R) in human ovarian carcinoma cell lines have been investigated. Ovarian carcinoma cells express both the IL-12R,1 and the IL-12R,2 subunits. IL-12R crosslinking resulted in phosphorylation of Tyk2, p44 (ERK1) and Akt kinases and activation of STATs 2, 3, 4 and 5. IL-12 induced substantial upregulation of Fas ligand (FasL) surface expression in ovarian carcinoma cells paralleled by an increased ability to induce apoptosis in Jurkat cells and PHA-activated lymphocytes. The induction of surface expression of FasL by IL-12 was not due to upregulation of FasL gene expression, but resulted from downregulation of matrix metalloproteinases (MMPs)-3 and -7 and consequently reduced cleavage of FasL from the cell surface. These findings bring new insights into the significance of IL-12-mediated effects in nonlymphoid cancer cells that might be of importance for improving the design of IL-12-based therapies for ovarian cancer. © 2004 Wiley-Liss, Inc. [source]

    Fas ligand expressed in colon cancer is not associated with increased apoptosis of tumor cells in vivo

    Aileen Houston
    Abstract Expression of Fas ligand (FasL/CD95L) may help to maintain colon cancers in a state of immune privilege by inducing apoptosis of antitumor immune effector cells. Colon tumor-derived cell lines appear to be relatively insensitive to apoptosis mediated by their own or exogenous FasL in vitro, despite expression of cell surface Fas. In our present study, we sought to investigate if FasL upregulated in human colon cancers leads to any increase in apoptosis of the tumor cells in vivo. FasL and Fas receptor (APO-1/CD95) expression by tumor cells were detected immunohistochemically. Apoptotic tumor cell death was detected by immunohistochemistry for caspase-cleaved cytokeratin-18. FasL expression did not correlate with the extent of apoptosis of tumor cells. There was no significant local difference in the frequency of apoptosis of tumor cells between tumor nests that expressed FasL (mean = 2.4%) relative to those that did not (mean = 2.6%) (p = 0.625, n = 10; Wilcoxon signed rank). FasL expressed by the tumor cells appeared to be functional, since FasL expression in tumor nests correlated with diminished infiltration of tumor-infiltrating lymphocytes (TILs). TILs were detected using immunohistochemistry for CD45. Expression of FasL by tumor nests was associated with a mean 4-fold fewer TILs relative to FasL-negative nests (range 2.4,33-fold, n = 10, p < 0.003). Together, our results indicate that colon tumors are insensitive to FasL-mediated apoptosis in vivo. © 2003 Wiley-Liss, Inc. [source]

    Participation of the Fas and Fas ligand systems in apoptosis during atrophy of the rat submandibular glands

    Shigeru Takahashi
    Summary Most acinar cells and some duct cells undergo apoptosis during atrophy of the submandibular gland. The present study was designed to elucidate whether Fas and its receptor ligand (FasL) are involved during apoptotic atrophy of the gland. The excretory duct of the right submandibular gland of rats was doubly ligated with metal clips from 1 to 14 days for induction of gland atrophy. Control rats were untreated. Fas and FasL expression in the atrophied submandibular gland was detected using immunohistochemistry (IHC) and Western immunoblot. Expression of activated caspase 8 and activated caspase 3 was also detected with IHC. Fas-positive acinar and duct cells and FasL-positive duct cells increased in the atrophic glands at 3 and 5 days after duct ligation when apoptotic cells were commonly observed. Thereafter, Fas- and FasL-positive cells declined in number. Patterns of expression of Fas and FasL using Western immunoblots concurred with the IHC results. Activated caspase 8-positive cells were present at every time interval but peaked at 3 and 5 days following duct ligation. The cells showing immunoreaction for activated caspase 3 first appeared on day 3, with the peak in apoptosis, after which they decreased. The results indicate that the Fas/FasL systems likely play an important role in apoptotic pathways during atrophy of the submandibular gland. [source]

    The central role of Fas-ligand cell signaling in inflammatory lung diseases

    G. A. DosReis
    Abstract Following inflammation and injury in the lung, loss of epithelial cell precursors could determine the balance between tissue regeneration and fibrosis. This review discusses evidence that proapoptotic Fas-Fas ligand (FasL) signaling plays a central role in pulmonary inflammation, injury and fibrosis. FasL signaling induces inflammatory apoptosis in epithelial cells and alveolar macrophages, with concomitant IL-1, and chemokine release, leading to neutrophil infiltration. FasL signaling plays a critical role in models of acute lung injury, idiopathic pulmonary fibrosis and silicosis; blockade of Fas-FasL interactions either prevents or attenuates pulmonary inflammation and fibrosis. Serologic and immunohistochemical studies in patients support a major pathogenic role of Fas and FasL molecules in inflammatory lung diseases. Identification of the pathogenic role of FasL could facilitate the discovery of more effective treatments for currently untreatable inflammatory lung diseases. [source]

    Contribution of apoptotic cell death to renal injury

    Alberto Ortiz
    Abstract Cell number abnormalities are frequent in renal diseases, and range from the hypercellularity of postinfectious glomerulonephritis to the cell depletion of chronic renal atrophy. Recent research has shown that apoptosis and its regulatory mechanisms contribute to cell number regulation in the kidney. The role of apoptosis ranges from induction to repair and progression of renal injury. Death ligands and receptors, such as TNF and FasL, proapoptotic and antiapoptotic Bcl-2 family members and caspases have all been shown to participate in apoptosis regulation in the course of renal injury. These proteins represent potential therapeutic targets, which should be further explored. [source]

    FAP-1-mediated activation of NF-,B induces resistance of head and neck cancer to fas-induced apoptosis

    Eva Wieckowski
    Abstract Molecular mechanisms responsible for tumor resistance to apoptosis often involve the Fas/FasL pathway. While squamous cell carcinomas of the head and neck (SCCHN) express both Fas and FasL, their resistance to self-induced apoptosis or apoptosis mediated by Fas agonistic antibody (CH-11Ab) was independent of the level of Fas surface expression or the presence of soluble Fas in supernatants of primary or metastatic SCCHN cell lines. By in vitro immunoselection, using PCI-15A cell line treated with successive cycles of CH-11 Ab, Fas-resistant sublines with the parental genotype were selected. Such sublines failed to cleave caspase-8 upon Fas engagement and were resistant to CH-11 Ab, although they remained sensitive to VP-16 or staurosporin. In the presence of cycloheximide, the selected SCCHN sublines become susceptible to CH-11 Ab, and showed cleavage of caspase-8, suggesting that apoptosis resistance was mediated by an inhibitory protein(s) acting upstream of caspase-8. Overexpression of Fas-associated phosphatase 1 (FAP-1), but not cellular FLICE-inhibitory protein (cFLIP) in SCCHN sublines was documented by Western blots and RT-PCR analyses. The FAP-1+ selected sublines also downregulated cell surface Fas. A high phosphorylation level of I,B,, NF,B activation and upregulation of Bcl-2 expression were observed in the FAP-1+ sublines. Treatment with the phosphatase inhibitor, orthovanadate, or silencing of FAP-1 with siRNA abolished their resistance to apoptosis, suggesting that FAP-1 phosphatase activity could be responsible for NF-,B activation and resistance of SCCHN cells to Fas-mediated apoptosis. J. Cell. Biochem. 100: 16,28, 2007. © 2006 Wiley-Liss, Inc. [source]

    FasL/Fas pathway is involved in dengue virus induced apoptosis of the vascular endothelial cells,,

    Hongwu Liao
    Abstract The hallmark of the dengue hemorrhagic fever/dengue shock syndrome is hematologic abnormality. The pathogenesis of dengue hemorrhagic fever/dengue shock syndrome remains unknown. Our work showed that the dengue virus serotype-2 induced apoptosis in human umbilical vein endothelial cells. Fas (CD95), Tumor Necrosis Factor receptors, and Tumor Necrosis Factor-related apoptosis-inducing ligand receptors are the most common death receptors, which can induce apoptosis. Compared with the untreated human umbilical vein endothelial cells, Fas expression was increased both in the mRNA level and on the surface of infected human umbilical vein endothelial cells. FasL was expressed at similar levels on human umbilical vein endothelial cells over a course of dengue virus serotype-2 infection, but the expression in mRNA level was increased in infected human umbilical vein endothelial cells. It is possible that there is soluble FasL secreted from human umbilical vein endothelial cells in the supernatant. Tumor Necrosis Factor-related apoptosis-inducing ligand receptor 1 and Tumor Necrosis Factor receptors 1,2 were constantly very low, whereas Tumor Necrosis Factor-related apoptosis-inducing ligand receptors 2,4 decreased after dengue virus serotype-2 infection. This result suggested that dengue virus serotype-2 may inhibit Tumor Necrosis Factor-related apoptosis-inducing ligand receptors-induced apoptosis. The apoptotic rates in human umbilical vein endothelial cells were decreased upon the addition of caspase family inhibitors. In addition, activated caspase 8 and caspase 3 were also observed by Western blot following dengue virus serotype-2 infection. Thus, it is shown that the Fas/FasL pathway may participate in dengue virus-induced apoptosis of vascular endothelial cells in vitro. J. Med. Virol. 82:1392,1399, 2010. © 2010 Wiley-Liss, Inc. [source]

    Lifeguard/neuronal membrane protein 35 regulates Fas ligand-mediated apoptosis in neurons via microdomain recruitment

    Miriam Fernández
    Abstract Fas ligand (FasL)-receptor system plays an essential role in regulating cell death in the developing nervous system, and it has been implicated in neurodegenerative and inflammatory responses in the CNS. Lifeguard (LFG) is a protein highly expressed in the hippocampus and the cerebellum, and it shows a particularly interesting regulation by being up-regulated during postnatal development and in the adult. We show that over-expression of LFG protected cortical neurons from FasL-induced apoptosis and decreased caspase-activation. Reduction of endogenous LFG expression by small interfering RNA sensitized cerebellar granular neurons to FasL-induced cell death and caspase-8 activation, and also increased sensitivity of cortical neurons. In differentiated cerebellar granular neurons, protection from FasL-induced cell death could be attributed exclusively to LFG and appears to be independent of FLICE inhibitor protein. Thus, LFG is an endogenous inhibitor of FasL-mediated neuronal death and it mediates the FasL resistance of CNS differentiated neurons. Finally, we also demonstrate that LFG is detected in lipid rafts microdomains, where it may interact with Fas receptor and regulate FasL-activated signaling pathways. [source]

    Activated JNK brings about accelerated apoptosis of Bcl-2-overexpressing C6 glioma cells on treatment with tamoxifen

    Madhavi S. Moodbidri
    Abstract Tamoxifen causes apoptosis of malignant glial cells at a concentration that does not kill normal astrocytes. C6 glioma cells were stably transfected with a vector expressing Bcl-2 under the control of metallothionin promoter. Low leaky Bcl-2 expression offered complete protection against tamoxifen-induced apoptosis. High Bcl-2 levels, on the other hand, accelerated the apoptosis, with Bcl-2-overexpressing clones dying within 48 h of tamoxifen treatment as compared to 6 days for parental C6 cells. Overexpressed Bcl-2 is localized primarily in mitochondria and to a much lower extent in endoplasmic reticulum (ER). Only a minor fraction of the overexpressed Bcl-2 gets phosphorylated in tamoxifen-treated cells and the phosphorylation does not affect its binding to Bax. Tamoxifen treatment of Bcl-2-overexpressing clones was found to result in activation of c-Jun N-terminal kinase (JNK) and p38 kinase. Inhibition of JNK but not p38 kinase completely abrogated the accelerated apoptosis. Constitutively expressed endogenous c-Jun was found to be phosphorylated, resulting in increased activator protein 1 (AP-1) DNA-binding activity. Expression of Fas ligand (FasL), an AP-1 transcriptional target, increased during accelerated cell death. This presumably brought about activation of caspase 8, as inhibition of caspase 8 blocked the apoptosis. The JNK/c-Jun/AP-1/FasL pathway could be considered as a potential target for the therapy of gliomas. [source]

    Transplantation of mesenchymal stem cells in a canine disc degeneration model

    Akihiko Hiyama
    Abstract Transplantation of mesenchymal stem cells (MSCs) is effective in decelerating disc degeneration in small animals; much remains unknown about this new therapy in larger animals or humans. Fas-ligand (FasL), which is only found in tissues with isolated immune privilege, is expressed in IVDs, particularly in the nucleus pulposus (NP). Maintaining the FasL level is important for IVD function. This study evaluated whether MSC transplantation has an effect on the suppression of disc degeneration and preservation of immune privilege in a canine model of disc degeneration. Mature beagles were separated into a normal control group (NC), a MSC group, and the disc degeneration (nucleotomy-only) group. In the MSC group, 4 weeks after nucleotomy, MSCs were transplanted into the degeneration-induced discs. The animals were followed for 12 weeks after the initial operation. Subsequently, radiological, histological, biochemical, immunohistochemical, and RT-PCR analyses were performed. MSC transplantation effectively led to the regeneration of degenerated discs. FACS and RT-PCR analyses of MSCs before transplantation demonstrated that the MSCs expressed FasL at the genetic level, not at the protein level. GFP-positive MSCs detected in the NP region 8 weeks after transplantation expressed FasL protein. The results of this study suggest that MSC transplantation may contribute to the maintenance of IVD immune privilege by the differentiation of transplanted MSCs into cells expressing FasL. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:589,600, 2008 [source]