Fas Ligand Gene Expression Research Articles

Highly Up-Regulation of Fas Ligand Gene Expression after Increasing in Oxidized Low-Density Lipoprotein

Oxidized low-density lipoprotein (ox-LDL) shows many harmful effects such as induction of apoptosis on function of endothelial cell (EC). Fas ligand (FASL) induces apoptosis in divergent pathological conditions. EC apoptosis which induced by ox-LDL is related with FASL. In this study, we aimed to determine how different ox-LDL levels affect FASL expression in ECs. We treated human umbilical vein endothelial cells (HUVECs) with two different concentration of ox-LDL. FASL gene expression in groups was detected by quantitative polymerase chain reaction (qPCR). We compared FASL gene expression level between the groups according to ∆∆Ct method. FASL gene expression was statistic significantly up-regulated in the group treated higher amounts of ox-LDL (P

Effect of Eight Weeks of Resistance Training and Consumption of Tribulus Terrestris on Androgenic Receptor-1, Fas Ligand Gene Expression, and Lipid Profiles in Rats Exposed to Stanozolol

Background: Protective effect of medicinal plants on the heart has been reported, but the effect of resistance training (RT) and Tribulus terrestris (TT) on the heart exposed to anabolic-androgenic steroids (AAS) abuse is still unknown. Objectives: The present study aimed to investigate the effect of RT and TT on androgen receptor-1 (ar-1), Fas ligand (fasl) gene expression and lipid profiles in rats exposed to stanozolol (S). Methods: Thirty-five male rats were selected and divided into 7 groups as follows: (1) sham (normal saline/Sh), (2) stanozolol (S), (3) S+100 mg/kg TT (S+TT100), (4) S+ 50 mg/kg TT (S+TT50), (5) S+RT+TT, (6) S+RT+TT100, and (7) S+RT+TT50. Over a course of eight-week period, groups 3, 4, 6, and 7 received 50 and 100 mg/kg/d doses of TT peritoneally and groups 5-7 performed three sessions of increasing RT per week. Results: RT decreased plasma cholesterol and low-density lipoprotein cholesterol (LDL-C) levels, as well as ar-1 and fasl gene expression in S-exposed rats (P<0.05). TT50, TT100, SRTT100, and SRTT50 reduced ar-1 and fasl gene expressions (P<0.05). TT50 reduced triglyceride (TG), cholesterol and increased high-density lipoprotein-cholesterol (HDL-C) (P≤0.01), and TT100 decreased LDL-C levels (P<0.05). Additionally, SRTT100 reduced TG, cholesterol, and LDL-C levels and increased HDL-C level (P<0.05), and SRTT50 decreased cholesterol level and increased HDL-C level in S-exposed rats (P<0.05). Conclusion: RT and consumption of TT appear to have protective effects on the improvement of apoptosisdependent androgen receptor-1 and lipid profile in S-exposed rats.

Promotion of extrinsic apoptosis pathway in HCT-116 human colorectal cancer cell line by sodium butyrate as histone deacetylase inhibitor

Background: Colorectal cancer (CRC) has already been considered the fourth leading cause of mortality worldwide as the genes involved in apoptotic pathways and alterations of reversible epigenetic have an important role in the progression of CRC. Objectives: The current study aimed to evaluate the effect of sodium butyrate as a histone deacetylase inhibitor on the alterations of the gene expression of FAS, Fas ligand (FASL), Death receptor 4 in HCT-116 CRC cell line. Methods: HCT-116 cell line was cultured in Dulbeccoʼs Modified Eagle Medium. The cytotoxicity effect of sodium butyrate on HCT-116 was evaluated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide assay for three incubation times (i.e., 24, 48, and 72 h). The half-maximal inhibitory concentration (IC50) values were determined. The optimum concentration was within the range of 6.25-200 mM. The cellular ribonucleic acid was extracted, and complementary deoxyribonucleic acid was synthesized. Finally, the alterations of the gene expression of FAS, FASL, DR4, DR5, and TRAIL were assessed by real-time polymerase chain reaction (PCR). Results: The IC50 levels for three incubation times were 50, 12.5, and 6.25 mM, respectively. The obtained results of real-time PCR demonstrated a significant increase in the gene expression of TRAIL, DR5, and FAS in comparison to that of the untreated cells as the control group at the three incubation times. The DR4 gene expression significantly increased in comparison to that reported for the control group at 48 and 72 h of incubation. In addition, FASL gene expression remarkably decreased at the three incubation times. Conclusions: Sodium butyrate could show cytotoxicity effect on CRC cell lines through the induction of death receptors in the extrinsic apoptotic pathway. The obtained results of this study revealed that the optimum effect of sodium butyrate is an incubation time-dependent and concentration-dependent manner.

Fas and Fas ligand gene polymorphisms in Turkish patients with Familial Mediterranean Fever

Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disorder characterized by recurrent fever, serositis, abdominal pain, arthritis, arthralgia and erysipelas like erythema. Fas and Fas ligand molecules play a central role in the apoptosis signaling of various cell types including neutrophils. Neutrophils are the major cell population involved in acute inflammation in patients with FMF and the role of Fas and Fas ligand molecules in this cells of FMF patients may be crucial. Therefore, in the present study, we aimed to investigate whether the Fas cell surface receptor gene (FAS); NM_000043.5: c.-671A>G (rs1800682, MvaI) and Fas ligand gene (FASLG), NM_000639.2: c.-844C>T (rs763110, BsrD1) functional polymorphisms in patients with FMF and their relation to the main clinical features of the disease. The polymorphisms in the promoter regions of FAS c.-671A>G and FASLG c.-844C>T were investigated in 97 non-related FMF patients and 70 non-related healthy controls by using PCR-RFLP technique. The frequencies of FAS c-671AG genotype and G allele were not significantly different between FMF patients and healthy subjects. The frequency of FASLG -844TC genotype was found significantly different between the patients with FMF and healthy controls whereas T or C allele frequency was not significantly different between the groups. Haplotype frequencies of the studied polymorphisms were also not significantly different between FMF patients and controls. There were no correlations between the studied FAS c.-671A>G and FASLG c.-844C>T polymorphisms and the main clinical features of FMF such as fever, arthritis, abdominal and chest pain, arthralgia and erysipelas-like erythema. Our findings suggest that FAS c.-671AG genotype or G allele and FASLG c.-844 allele are not to be a risk factor, whereas FASLG c.-844TC genotype may be protective in the studied Turkish population. According to our results we may suggest that although not statistically significant, higher frequencies of FASLG c.-844CC genotype in FMF patients may be related to delayed apoptosis of neutrophils and ultimately cause neutrophilic inflammation by increasing FASLG expression.

Testosterone induces apoptosis in vascular smooth muscle cells via extrinsic apoptotic pathway with mitochondria-generated reactive oxygen species involvement

Testosterone exerts both beneficial and harmful effects on the cardiovascular system. Considering that testosterone induces reactive oxygen species (ROS) generation and ROS activate cell death signaling pathways, we tested the hypothesis that testosterone induces apoptosis in vascular smooth muscle cells (VSMCs) via mitochondria-dependent ROS generation. Potential mechanisms were addressed. Cultured VSMCs were stimulated with testosterone (10(-7) mol/l) or vehicle (2-12 h) in the presence of flutamide (10(-5) mol/l), CCCP (10(-6) mol/l), mimetic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP; 3 × 10(-5) mol/l), Z-Ile-Glu(O-ME)-Thr-Asp(O-Me) fluoromethyl ketone (Z-IETD-FMK; 10(-5) mol/l), or vehicle. ROS were determined with lucigenin and dichlorodihydrofluorescein; apoptosis, with annexin V and calcein; O2 consumption, with a Clark-type electrode, and procaspases, caspases, cytochrome c, Bax, and Bcl-2 levels by immunoblotting. Testosterone induced ROS generation (relative light units/mg protein, 2 h; 162.6 ± 16 vs. 100) and procaspase-3 activation [arbitrary units, (AU), 6 h; 166.2 ± 19 vs. 100]. CCCP, MnTMPyP, and flutamide abolished these effects. Testosterone increased annexin-V fluorescence (AU, 197.6 ± 21.5 vs. 100) and decreased calcein fluorescence (AU, 34.4 ± 6.4 vs. 100), and O2 consumption (nmol O2/min, 18.6 ± 2.0 vs. 34.4 ± 3.9). Testosterone also reduced Bax-to-Bcl-2 ratio but not cytochrome-c release from mitochondria. Moreover, testosterone (6 h) induced cleavage of procaspase 8 (AU, 161.1 ± 13.5 vs. 100) and increased gene expression of Fas ligand (2(ΔΔCt), 3.6 ± 1.2 vs. 0.7 ± 0.5), and TNF-α (1.7 ± 0.4 vs. 0.3 ± 0.1). CCCP, MnTMPyP, and flutamide abolished these effects. These data indicate that testosterone induces apoptosis in VSMCs via the extrinsic apoptotic pathway with the involvement of androgen receptor activation and mitochondria-generated ROS.

Emodin induces cytotoxic effect in human breast carcinoma MCF-7 cell through modulating the expression of apoptosis-related genes

Context: The poor prognostic outcome of breast cancer is largely due to its resistance to cancer therapies. Development of therapeutic agents that can inhibit growth and induce apoptosis in breast cancer cells can help solve the problem. Emodin is an active anthraquinone that has been reported to have diverse biological effects.Objective: In this study, the anticancer effects of emodin on growth inhibition, apoptosis induction and the expression of apoptosis-related genes in MCF-7 cells were investigated.Materials and methods: Growth inhibition induced by emodin was investigated by the MTS assay and the colony formation assay; while emodin-induced apoptosis was determined by the COMET assay and DNA fragmentation detection. Emodin (35 μM)-induced alterations in the expression of apoptotic-related genes were detected by using real-time PCR.Results: Emodin had significant growth inhibitory effects on MCF-7 cells with IC50 = 7.22 µg/ml (∼30 μM). It also exerted a concentration-dependant inhibitory effect on the colony-forming ability of MCF-7 cells with IC50 = 7.60 µg/ml (∼30 µM). Hallmarks of apoptosis, such as single-strand DNA breakage and DNA fragmentation, were observed in emodin-treated MCF-7 cells. The gene expression of Fas ligand (FASL) was up-regulated (p < 0.01) but those of MCL1, CCND1 and C-MYC were down-regulated (p < 0.05) in emodin-treated MCF-7 cells.Discussion and conclusion: This study indicated that emodin could induce growth inhibition and apoptosis in MCF-7 cells through the modulation of the expression of apoptosis-related genes. The growth inhibitory effects of emodin might involve both the intrinsic and the extrinsic apoptotic pathways and cell cycle arrest.

The effect of rotative stress on CAII, FAS, FASL, OSCAR, and TRAP gene expression in osteoclasts

This study was designed to explore the effects of rotative stress on carbonic anhydrase II (CAII), TNF receptor superfamily member 6 (FAS), FAS ligand (FASL), osteoclast-associated receptor (OSCAR), and tartrate-resistant acid phosphatase (TRAP) gene expression in osteoclasts. Osteoclasts were induced from RAW264.7 cells cultured in medium containing recombinant murine soluble receptor activator of NF-Kβ ligand (sRANKL). The mRNA and protein expression of CAII, FAS, FASL, OSCAR, and TRAP genes in osteoclasts was detected by RT-PCR and Western blot, respectively, after osteoclasts were loaded at various rotative stress strengths and times. No significant differences in mRNA and protein expression were observed between any of the control groups (P > 0.05). Importantly, rotative stress had a significant effect on the mRNA and protein expression of these genes (P < 0.05). We found a negative relationship between rotative stress strength and prolonged loading time and the expression of FAS/FASL genes in osteoclasts. In addition, there was a positive relationship between rotative stress strength and prolonged loading time and the expression of CAII, OSCAR, or TRAP genes in osteoclasts. Based on these results, rotative stress has a significant effect on CAII, FAS, FASL, OSCAR, and TRAP gene expression in osteoclasts.

Fas ligand gene expression is directly regulated by stress-inducible heat shock transcription factor-1

Heat shock transcription factor-1 (HSF-1) is the primary stress responsive transcription factor that regulates expression of heat shock proteins (Hsps) in response to elevated temperature. We show that the transcriptional activity of HSF-1 can also directly mediate hyperthermia-induced Fas ligand (FasL) expression in activated T cells. We identify a conserved region within the human FasL promoter spanning from -276 to -236 upstream of the translational start site that contains two 15 bp non-identical adjacent HSF-1-binding sites or heat shock elements (HSEs) separated by 11 bp. Both the distal HSE (HSE1) (extending from -276 to -262) and the proximal HSE (HSE2) (spanning from -250 to -236) consist of two perfect and one imperfect nGAAn pentamers. We show the direct binding of HSF-1 to these elements and that mutation of these sites abrogates the ability of HSF-1 to bind and drive promoter activity. HSF-1 associates with these elements in a cooperative manner to mediate optimal promoter activity. We propose that the ability of HSF-1 to mediate stress-inducible expression of FasL extends its classical function as a regulator of Hsps to encompass a function for this transcription factor in the regulation of immune function and homeostasis.

317. DIFFERENTIAL EFFECTS OF cAMP AND CRH IN CELL VIABILITY AND CELL FUSION OF CYTOTROPHOBLASTIC CELLS

Cell fusion of cytotrophoblasts is critical for a successful pregnancy, and is marked biochemically by proteins such as human chorionic gonadotrophin (hCG) and syncytin, and morphologically as large multi-nucleated cells. Placental corticotrophin releasing hormone (CRH) plays diverse roles during pregnancy and has been linked to the length of gestation. It is well accepted that CRH expression could be upregulated by some hormones, such as hCG via cellular cAMP, and that trophoblastic cell fusion can be induced by Forskolin (increases cAMP). We have shown, by reporter gene assay in human primary placental cells, that 8-Br-cAMP increased CRH gene expression. Thus, it is of interest to determine the roles of 8-Br-cAMP and CRH on trophoblast cell viability and cell fusion. Treatment with 8-Br-cAMP for 72 h significantly inhibited BeWo cell viability (MTT assay) by 29.7% (50 μM) and 54.8% (100 μM), and increased both apoptotic and necrotic cells (FACS analysis). 8-Br-cAMP (100 μM, 48 h) resulted in the appearance of nuclear fragments (DAPI stain) and Fas ligand gene expression by 6.8-fold (real-time RT-PCR). Syncytin 1 mRNA increased by 3.2-fold (real-time RT-PCR) and hCG secretion increased by 4-fold (ELISA assay). The formation of syncytium (CellMask and Hoechst co-stain) could clearly be seen by 72 h. CRH mRNA increased with 8-Br-cAMP treatment of BeWo cells (15-fold at 48 h). Treatment with CRH (100 nM) had a mild inhibitory effect on cell growth (~18%) but no effect on cell viability, up-regulated the expression of syncytin 1 mRNA (2.3-fold at 48 h) and induced cell fusion (72 h), but had no effect on hCG secretion. In summary, we show that 8-Br-cAMP and CRH are both potential inducers of cytotrophoblast cell fusion, and there is a dissociation between morphological and biochemical differentiation. Our data also indicates that the process of cell fusion can be associated with both apoptotic and non-apoptotic events.

Toll-like receptors, chemokine receptors and death receptor ligands responses in SARS coronavirus infected human monocyte derived dendritic cells

BackgroundThe SARS outbreak in 2003 provides a unique opportunity for the study of human responses to a novel virus. We have previously reported that dendritic cells (DCs) might be involved in the immune escape mechanisms for SARS-CoV. In this study, we focussed on the gene expression of toll-like receptors (TLRs), chemokine receptors (CCRs) and death receptor ligands in SARS-CoV infected DCs. We also compared adult and cord blood (CB) DCs to find a possible explanation for the age-dependent severity of SARS.ResultsOur results demonstrates that SARS-CoV did not modulate TLR-1 to TLR-10 gene expression but significantly induced the expression of CCR-1, CCR-3, and CCR-5. There was also strong induction of TNF-related apoptosis-inducing ligand (TRAIL), but not Fas ligand gene expression in SARS-CoV infected DCs. Interestingly, the expressions of most genes studied were higher in CB DCs than adult DCs.ConclusionThe upregulation of chemokines and CCRs may facilitate DC migration from the infection site to the lymph nodes, whereas the increase of TRAIL may induce lymphocyte apoptosis. These findings may explain the increased lung infiltrations and lymphoid depletion in SARS patients. Further explorations of the biological significance of these findings are warranted.

Importance of forkhead transcription factor Fkhl18 for development of testicular vasculature

Forkhead transcription factors are characterized by a winged helix DNA binding domain, and the members of this family are classified into 20 subclasses by phylogenetic analyses. Fkhl18 is structurally unique, and is classified into FoxS subfamily. We found Fkhl18 expression in periendothelial cells of the developing mouse fetal testis. In an attempt to clarify its function, we generated mice with Fkhl18 gene disruption. Although KO mice developed normally and were fertile in both sexes, we frequently noticed unusual blood accumulation in the fetal testis. Electron microscopic analysis demonstrated frequent gaps, measuring 100-400 nm, in endothelial cells of blood vessels. These gaps probably represented ectopic apoptosis of testicular periendothelial cells, identified by caspase-3 expression, in KO fetuses. No apoptosis of endothelial cells was noted. Fkhl18 suppressed the transcriptional activity of FoxO3a and FoxO4. Considering that Fas ligand gene expression is activated by Foxs, the elevated activity of Foxs in the absence of Fkhl18 probably explains the marked apoptosis of periendothelial cells in Fkhl18 KO mice.

Death receptors in cervical cancer

Death-prone T cells might increase the risk of developing cervical cancer, according to a study on page 967. Sun and colleagues show that women with cervical cancer are more likely to have T cells that are genetically programmed to express high levels of the death-inducing molecule FAS ligand (FASL).Most cervical cancers are associated with human papillomavirus (HPV) infection. But not all HPV-infected women develop cervical cancer, suggesting that other factors contribute to cancer progression. A recent study linked cervical cancer with a genetic polymorphism in the gene encoding the death receptor FAS, which triggers apoptosis when bound by its ligand FASL. However, these findings are controversial as other studies failed to confirm this association. Figure T cells homozygous for the −844C FASL polymorphism express more FASL when activated. Sun and colleagues now find that a naturally occurring polymorphism in the FASL promoter was three times more prevalent in Chinese women with cervical cancer than in cancer-free controls. T cells with this single nucleotide polymorphism (−844C) expressed more FASL and were more prone to cell death after stimulation with cervical cancer cells than T cells without the polymorphism (−844T). Although the mechanism remains obscure, the authors suggest that an increased propensity for cell death might limit the ability of tumor-specific T cells to eradicate tumor cells. The −844C polymorphism was recently found to improve the binding of a transcription factor that helps drive FASL gene expression, and to increase FASL protein levels on fibroblasts. In that study, the polymorphism was linked to the autoimmune disease systemic lupus erythematosus (SLE). The link to SLE was postulated to result from increased FAS-mediated cell death, which might facilitate the release of nuclear antigens that are then targeted by the immune response.

The Use Of Real-Time Quantitative Polymerase Chain Reaction To Detect Hypermethylation Of The Cpg Islands In The Promoter Region Flanking The Gstp1 Gene To Diagnose Prostate Carcinoma

We developed a real-time, quantitative, methylation sensitive polymerase chain reaction (PCR) protocol to analyze hypermethylation of the CpG islands in the promoter region of the pi class glutathione-S-transferase gene GSTP1 in prostate cancer tissue. A total of 21 prostate cancer and 72 benign prostate hyperplasia (BPH) tissue samples were analyzed. Genomic DNA was digested with restriction enzyme, followed by real-time quantitative PCR amplification. Cycle threshold values were used to determine whether cancer genome was present in these tissues. A cutoff cycle threshold value of 35 was arbitrarily assigned. Samples with a cycle threshold of 35 or less were considered positive for prostate cancer. Conventional nested PCR was also performed for comparison. The mean cycle threshold values plus or minus standard deviation in prostate cancer and BPH cases were 30.12 +/- 2.88 and 37.77 +/- 2.72, respectively. All prostate cancer samples analyzed showed positive results, while 5 of the 72 BPH samples tested positive. Conventional nested PCR data indicated that 19 of 21 prostate cancer cases were positive for the methylation change, while 71 of 72 BPH cases tested negative. The test limitations of real-time PCR and the nested PCR protocols were determined to be 0.048 and 0.64 ng. DNA, respectively. We established a novel protocol for detecting the methylation change in the 5' regulatory sequence flanking the GSTP1 gene. The sensitivity of this protocol was superior to that of conventional nested PCR. The data also suggest that this novel protocol may accurately discriminate prostate carcinoma from BPH.

Molecular mechanisms of aortic wall remodeling in response to hypertension

Objective: The molecular basis of vascular response to hypertension is largely unknown. Both cellular and extracellular components are critical. In the current study we tested the hypothesis that there is a balance between vascular cell proliferation and cell death during vessel remodeling in response to hypertension. Methods: A midthoracic aortic coarctation was created in rats to induce an elevation of blood pressure proximal to the coarctation. The time course was 1 and 3 days and 1, 2, and 4 weeks for the study of the proximal aorta. Ribonuclease protection assay and Western blot analysis were used to evaluate gene expression of growth and apoptosis-related cytokines with two sets of multiple probes, rCK-3 and rAPO-1. Cell proliferation was determined with BrdU (5-bromo-2′-deoxyuridine) incorporation. Apoptosis was examined with TUNEL (transferase-mediated dUTP nick end-labeling). Morphometry was performed on histologic sections. Results: Coarctation produced hypertension in the proximal aorta, 118 ± 9 mm Hg versus 94 ± 6 mm Hg in controls (P <.002). Both messenger RNA and protein levels of transforming growth factor (TGF)–β1 and TGF-β3 were increased (P <.005 vs controls). Messenger RNA and protein of Bcl-xS and Fas ligand, known as proapoptotic factors, were both reduced after coarctation (P <.005 vs controls). There was increased BrdU incorporation at 3 days and 1 and 2 weeks (P <.001 vs controls). There were no remarkable changes in the apoptosis rate until 4 weeks later. Conclusion: Cell proliferation was stimulated at 3 days, and apoptosis was halted until 4 weeks. These changes were associated with upregulation of TGF-β and downregulation of Bcl-xS and Fas ligand gene expression. These findings suggest that a coordinated regulation of cell proliferation and cell death contributes to arterial remodeling in response to acute sustained elevation of blood pressure. Cell proliferation precedes apoptosis by 2 weeks in this procedure. (J Vasc Surg 2001;33:570-8.)

Quantitation of Fas and Fas ligand gene expression in human ovarian, cervical and endometrial carcinomas using real-time quantitative RT-PCR.

Alterations in the expression of Fas (CD95/APO-1) and its ligand (FasL) have been demonstrated in various types of cancers as a mechanism for tumour cell to escape from the immune system. In the present study, we evaluated the expression of the Fas and FasL genes in a wide range of primary gynaecological carcinomas. These included 31 ovarian, 29 cervical and 25 endometrial carcinoma tissues as well as four ovarian and three cervical carcinoma cell lines. Our real-time quantitative reverse transcription polymerase chain reaction analysis revealed that down-regulation of Fas expression is more prominent than the up-regulation of FasL expression in all types of gynaecological cancer studied. This down-regulation of Fas expression was also true for the seven carcinoma cell lines. Only one cervical carcinoma cell line, DoT, exhibited a high level of FasL expression. These results indicated that down-regulation of Fas expression is a common abnormality in many types of cancers including gynaecological cancers, whereas an increase in FasL expression is not a common phenomenon in these cancers. © 2000 Cancer Research Campaign

Gene expression of fas ligand in Kupffer cells following rat orthotopic liver transplantation

Gene expression of fas ligand in Kupffer cells following rat orthotopic liver transplantation

Differential effects of B7-1 and B7-2 on the costimulation of mouse nonspecific cytotoxic T lymphocyte development in response to anti-CD3 antibody.

Despite extensive study, the relative contribution of B7-1 and B7-2 molecules to the costimulation of cytotoxic T lymphocyte (CTL) activation remains controversial. We used blocking mAbs to B7-1 and B7-2 molecules to determine the role of these B7 family members in the in vitro induction of mouse nonspecific CTL in response to soluble anti-CD3 mAb. Optimal induction of anti-CD3-activated killer-T (AK-T) cells was found to require interactions with B7-2 on residual accessory cells in nylon wool-nonadherent spleen cell preparations during the first 12 h of culture in the presence of anti-CD3 mAb. Because B7-1 is not expressed at high enough levels on residual accessory cells in primary T cell cultures to be an effective ligand for CD28, we used LPS-stimulated B cells, which express substantial B7-1, in addition to B7-2, to determine the contribution of B7-1 to AK-T cell development. Compared with B7-2, the contribution of B7-1 to the costimulation of AK-T cells in this system was modest because anti-B7-1 mAb had only a minimal inhibitory effect on the generation of cytotoxicity, whereas anti-B7-2 mAb strongly inhibited AK-T cell development. Anti-CD3-induced cytotoxicity of T cells from CD4 knockout mice and CD4-depleted nylon wool-nonadherent spleen cells from wild-type mice was inhibited by anti-B7-2 mAb, implying that B7-2 is able to bind directly to CD28 on CD8+ T cells and costimulate their activation. B7-1 blockade, on the other hand, did not affect the costimulation of CD8+ T cells. Blockade of B7-2/ CD28 interactions with anti-B7-2 mAb strongly inhibited granzyme B, but not perforin or Fas ligand gene expression, suggesting an explanation for the inhibitory effect of anti-B7-2 mAb on AK-T cell development. These data indicate that B7-2 is superior to B7-1 as a costimulator of mouse AK-T cell induction.

On/off switching fas–ligand gene expression in liver by Cre/Loxp adenovirus vector system

On/off switching fas–ligand gene expression in liver by Cre/Loxp adenovirus vector system

Anti-CD3-activated killer T cells: Interleukin-6 modulates the induction of major histocompatibility complex-unrestricted cytotoxicity and the expression of genes coding for cytotoxic effector molecules.

We have investigated the role of interleukin-6 (IL-6) in the induction of major histocompatibility complex (MHC)-unrestricted cytotoxicity, as well as granzyme B, perforin, and Fas ligand gene expression, following mouse T lymphocyte activation with anti-CD3 monoclonal antibody (mAb). The generation of anti-CD3-activated killer-T (AK-T) cells was inhibited when anti-IL-6 neutralizing mAb was added at initiation of culture but not 24 h later, indicating that IL-6 is involved at an early stage of AK-T cell development. However, AK-T cell induction in the presence of exogenous IL-6 did not result in enhanced cytotoxicity, suggesting that saturating levels of IL-6 are normally synthesized in AK-T cell cultures. The inhibitory effect of IL-6 neutralization on AK-T cell generation could not be attributed to a defect in AK-T cell proliferation or to an inability of AK-T cells to recognize and adhere to P815 tumor target cells. However, IL-2 synthesis and CD25 expression were downregulated in AK-T cell cultures performed in the presence of anti-IL-6 mAb. In addition, IL-6 neutralization resulted in decreased expression of granzyme B and perforin, but not Fas ligand, mRNA. Exogenous IL-2 (50 U/ml) added at initiation of culture completely reversed the inhibitory effect of anti-IL-6 mAb on AK-T cell development, restoring CD25 expression and tumoricidal activity, as well as granzyme B and perforin mRNA expression, to control levels. We conclude that IL-6 modulates AK-T cell induction through an IL-2-dependent mechanism.

Expression of Fas and Fas ligand in renal grafts with acute and chronic rejection in the rat model.

The Fas system-based rejection mechanism has not been studied well in terms of cytotoxic T cell activity in graft rejection. We investigated the Fas and Fas ligand level in renal grafts with acute and chronic rejection in a rat model using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Fas ligand in renal allografts was detected as early as 1 day after transplantation in an acute rejection model. It was highly expressed at day 4 and began to decline at day 6 after transplantation. In contrast, Fas ligand in normal kidneys was almost undetectable. Fas ligand in isografts was increased, but the expression level was much lower than in allografts. Interestingly, when Fas ligand expression began to decline in renal allografts, it increased in the spleens of recipients. Fas ligand expression in chronically rejecting allografts was slightly increased, but it was stronger than in isografts. In contrast to Fas ligand gene expression, Fas was constitutively expressed in isografts, allografts, and normal kidneys. However, the Fas level in renal allografts was higher than in normal kidneys. Our data demonstrated that the Fas system might play an important role in acute and chronic rejection by causing apoptosis, and the spleen may eliminate the lymphocytes strongly expressing Fas ligand after completion of the acute rejection.