Mouse Fas Ligand Research Articles

Cumulus cells accelerate oocyte aging by releasing soluble Fas ligand in mice.

Although previous studies have suggested that cumulus cells (CCs) accelerate oocyte aging by secreting soluble and heat-sensitive paracrine factors, the factors involved are not well characterized. Because Fas-mediated apoptosis represents a major pathway in induction of apoptosis in various cells, we proposed that CCs facilitate oocyte aging by releasing soluble Fas ligand (sFasL). In this study, we reported that when the aging of freshly ovulated mouse oocytes were studied in vitro, both the apoptotic rates of CCs and the amount of CCs produced sFasL increased significantly with the culture time. We found that oocytes expressed stable levels of Fas receptors up to 24 h of in vitro aging. Moreover, culture of cumulus-denuded oocytes in CCs-conditioned CZB medium (CM), in CZB supplemented with recombinant sFasL, or in CM containing sFasL neutralizing antibodies all showed that sFasL impaired the developmental potential of the oocytes whereas facilitating activation and fragmentation of aging oocytes. Furthermore, CCs from the FasL-defective gld mice did not accelerate oocyte aging due to the lack of functional FasL. In conclusion, we propose that CCs surrounding aging oocytes released sFasL in an apoptosis-related manner, and the released sFasL accelerated oocyte aging by binding to Fas receptors.

IL-1β regulates the mouse Fas ligand expression in corneal endothelial cells

Constitutively expressed Fas ligand (FasL) in several distinct epithelial cell types appears to protect tissues by inducing apoptosis of Fas+ immune cells during inflammatory reactions. To study the relationship of FasL and inflammation process in cornea, we examined the effects of inflammatory cytokine IL-1β on the FasL production, expression and cytotoxic function in corneal endothelial cells. In this paper, we demonstrate that IL-1β inhibits the FasL production and expression in corneal endothelial cells. The promoter activities of FasL in these cells are reduced by IL-1β in a dose-dependent manner. Finally, we also find that IL-1β block the cytotoxic effects of FasL derived from corneal endothelial cells to the Fas+ target cells. These data support the view that FasL derived from corneal endothelial cells modulate inflammation within cornea.

Attenuation of GVHD for allo-bone marrow transplantation recipient by FasL-Fas pathway in an H-2 haplotype disparate mouse combination.

In order to explore a new special and effective way to prevent graft versus host disease (GVHD) after allogenic bone marrow transplantation (allo-BMT), the stem cell antigen-1 (Sca-1) + early hematopoietic cells (EHC) from BALB/c mouse (H-2d) were introduced with exogenous mouse Fas ligand (mFasL) cDNA gene by the retrovirus-mediated gene transfer and expanded for one week, and then they were co-cultured with the spleen mononuclear cells (SMNC) from BAC mouse (H-2dxb) as one way mixed lymphocyte reaction (OWMLR). The cytotoxicity of treated BAC mouse SMNC against Na2 51CrO4 labeling SMNC from BALB/c mouse was observed. The bone marrow mononuclear cells (BMMNC) from BAC mouse treated by the above methods were transplanted into lethally-irradiated congenic BALB/c mice to observe the occurrence of GVHD. The results showed that the SMNC from BAC mouse after OWMLR with exogenous mFasL cDNA gene-transduced hematopoietic cells (HC) from BALB/c mouse in a ratio of 1 to 5 exhibited an obvious inhibition of the cytotoxicity against the BALB/c mouse spleen cells at different effector/target ratios as compared to the control group (P<0.01). The grade I GVHD or no GVHD and the 80% survival rate at day 60 post-BMT were observed in the BALB/c mouse receiving BAC mouse BMMNC treated with similar way, while the grade II - III GVHD and the 20% survival rate were noted in the control group (P<0.01). It is suggested that the attenuation of GVHD in allo-BMT recipient could be successfully achieved through FasL-Fas pathway in an H-2 haplotype disparate mouse combination.

Lethal effect of recombinant human Fas ligand in mice pretreated with Propionibacterium acnes.

Fas ligand (FasL) is a type II membrane protein. Binding of FasL to its receptor, Fas, induces apoptosis. Matrix metalloproteinase cleaves the membrane-bound human FasL to yield the active soluble form. Here, we have produced a large amount of human soluble rFasL using the yeast, Pichia pastoris. The purified rFasL was found to be glycosylated and to exist as a trimer. The rFasL was effective in inducing apoptosis in a Fas-expressing T cell or a fibroblast cell line. The ID50 of rFasL for mouse Fas-expressing T cells was about 0.5 ng/ml. The killing process with rFasL was quick. That is, >80% Fas-expressing mouse cells were killed within 1 h by a saturation concentration of human rFasL. Intravenous administration of 500 microg of human rFasL had a lethal effect in mice. When the mice were pretreated with Propionibacterium acnes, the subsequent injection of 30 microg of human rFasL induced hepatic failure and killed the mice within 24 h. These results indicated that the soluble human FasL is active in inducing apoptosis in vitro and in vivo, and its deleterious effect may be strengthened in patients who are suffering from bacterial infection.

Role of Fas Ligand in Apoptosis Induced by Hepatitis C Virus Infection

To investigate the role that Fas ligand plays in the apoptosis of hepatocytes induced by hepatitis C virus infection, we isolated a cDNA clone for human Fas ligand and examined the expression of Fas ligand in liver-infiltrating mononuclear cells obtained from patients with chronic hepatitis C. The amino acid sequence of human Fas ligand showed 76% and 77% identity with those of rat and mouse Fas ligand, respectively. When the expression of Fas ligand transcripts was tested by reverse transcription-polymerase chain reaction, the amplified signal was detected in liver-infiltrating mononuclear cells and peripheral blood mononuclear cells, whereas only a weak signal or none at all was detected in liver tissues. These findings suggest that the Fas ligand-Fas antigen system may play an important role in liver cell injury by hepatitis C virus infection.