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Previous investigations have demonstrated the adverse impacts of fluoride on Sertoli cells (SCs), such as oxidative stress and apoptosis. SCs are the crucial cellular components that can create the immune privileged environment in testis. However, the effect of fluoride on SCs immune privilege is unknown. In this study, mouse SCs were exposed to sodium fluoride with varying concentrations of 10 −5 , 10 −4 , and 10 −3 mol/L to establish the model of fluoride-treated SCs (F-SCs) in vitro. After 48 h of incubation, F-SCs were transplanted underneath the kidney capsule of mice for 21 days, or cocultured with spleen lymphocytes for another 48 h. Immunohistochemical analysis of GATA4 in SCs grafts underneath kidney capsule presented less SCs distribution and obvious immune cell infiltration in F-SCs groups. In addition, the levels of FasL protein and mRNA in non-cocultured F-SCs decreased with the increase of fluoride concentration. When cocultured with F-SCs, lymphocytes presented significantly high cell viability and low apoptosis in F-SCs groups. Protein and mRNA expressions of FasL in cocultured F-SCs and Fas in lymphocytes were reduced, and the caspase 8 and caspase 3 mRNA levels were also decreased in fluoride groups in a dose-dependent manner. These findings indicated that fluoride influenced the testicular immune privilege through disturbing the Fas/FasL system. [ABSTRACT FROM AUTHOR]

Com os avanços terapêuticos que incluem o mesilato de imatinibe, o transplante de medula óssea e a infusão de linfócito do doador, a perspectiva de vida dos portadores de leucemia mielóide crônica (LMC) tem aumentado significativamente e a doença pode não ser fatal. No entanto, os mecanismos biológicos que privilegiam a seleção das células hematopoéticas malignas sobre as células normais na LMC, responsáveis pelo insucesso terapêutico em muitos casos, ainda não estão totalmente esclarecidos. Alterações no processo de apoptose celular e escape das células leucêmicas à resposta imune antitumoral poderiam explicar, em parte, a vantagem seletiva dessas células. O processo de apoptose celular pode ser desencadeado pelas vias intrínseca ou extrínseca. A extrínseca é dependente da interação de receptores de morte celular, como a ligação do receptor Fas com seu receptor, o Fas ligante (FasL). A expressão diminuída de Fas e aumentada de FasL na célula leucêmica podem aumentar sua sobrevida tornando-a resistente à apoptose. Esse artigo descreve a relação entre LMC e o sistema Fas/FasL, sua possível importância no prognóstico e escape das células leucêmicas à resposta imune.With therapeutic advances that include imatinib mesylate, bone marrow transplantation and donor lymphocyte infusion, life expectancy of chronic myeloid leukemia carriers has increased significantly and the disease might not be fatal. However, the biological mechanisms that favor the selection of malignant clone cells over normal cells, in most cases responsible for the lack of therapeutic success, are still unclear. Alterations in cellular apoptosis process and escape of the leukemic cells from the anti-tumor immune response can explain, in part, the selective advantages of these cells. The apoptosis process or programmed cell death can be triggered by intrinsic or extrinsic pathways. The extrinsic is dependent on the interaction of cell death receptors, such as the Fas receptor and its agonist, the Fas ligand (FasL). A diminished expression of Fas and increased of FasL in leukemic cell may increase its survival, thereby making it resistant to apoptosis. This paper describes the relation between chronic myeloid leukemia and the Fas/FasL system and its possible importance in prognosis and in escape of the leukemic cells from the immune system.

Acute liver failure (ALF) is a life threatening disease for which only few treatment options exist. The molecular pathways of disease progression are not well defined, but the death receptor Fas (CD95/Apo-1) appears to play a pivotal role in hepatocyte cell death and the development of ALF. Here, we explored posttranscriptional gene silencing of Fas by RNAi to inhibit pathophysiological gene expression. For targeting Fas expression in mice, Fas siRNA was formulated with the liver-specific siRNA delivery system DBTC. Treatment of mice with DBTC/siRNA reduced Fas expression in the liver, but not in the spleen, lung, kidney or heart. Furthermore, silencing of Fas receptor was effective in blocking or reducing several aspects of ALF when it was tested in mice exposed to galactosamine/lipopolysaccharide (G/L), a well-known model of ALF. The application of DBTC/siRNA 48 h prior G/L exposure resulted in amelioration of hepatic perfusion, reduction of hepatocellular death and increase of survival rate. The administration of DBTC/siRNA formulation further diminished the inflammatory response upon G/L challenge, as indicated by a marked decrease of TNFα mRNA expression. However, IL-6 plasma concentration remained unaffectedly by DBTC/siRNA formulation. Since the specific silencing of hepatic Fas expression only partially protected from inflammation, but completely attenuated apoptotic and necrotic cell death as well as microcirculatory dysfunction, the development of therapeutic strategies with DBTC lipoplex formulations to treat ALF should be combined with anti-inflammatory strategies to reach maximal therapeutic efficacy. [ABSTRACT FROM AUTHOR]

This study explored the effects of nuclear factor-kappa B (NF-κB) inhibitor Bay 11-7082 on Fas/FasL system and Fas-mediated apoptosis in cell line HL-60 cells. The mRNA and protein levels of Fas, FasL, and X-linked inhibitor of apoptosis protein (XIAP) were detected by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry (FCM); the level of sFasL was evaluated by enzyme-linked immunosorbent assay (ELISA); and apoptosis was determined by FCM. After treatment with Bay 11-7082, the mRNA and protein levels of FasL and XIAP in HL-60 cells were significantly lower than in the controls ( P < 0.05), but the mRNA and protein levels of Fas and sFasL did not change significantly ( P > 0.05). Apoptotic rate of HL-60 cells treated with Bay 11-7082 was significantly higher than in the controls ( P < 0.05). Therefore, we conclude that Bay 11-7082 can enhance Fas-mediated apoptosis in HL-60 cells by downregulating FasL and XIAP levels. [ABSTRACT FROM AUTHOR]

Abstract: Lindane, an organochlorine pesticide, is known to impair testicular functions and fertility. To elucidate the mechanism(s) underpinning the gonadal effects of lindane, we sought to investigate the levels of apoptosis-related proteins, namely cytochrome c, caspase-3 and-9, Fas and FasL in the testis of adult rats. Furthermore, the study aims to delineate whether nuclear factor kappa B (NF-κB) is involved in meditating the testicular effects of lindane. Animals were administered with a single dose of lindane (5mg/kg body weight) and sacrificed at specific post-treatment intervals (0, 3, 6, 12, 24 and 72h). Significant elevations in the levels of cytosolic cytochrome c with a parallel increase in pro-caspase-9 were observed as early as 6h following exposure. Time-dependent elevations in the levels of Fas, FasL and caspase-3 were observed. Immunofluorescence studies revealed increased colocalization of Fas and caspase-3 in peritubular germ cells. FasL levels were increased in Sertoli and peritubular germ cells. The cytoplasmic levels of NF-κB p65 decreased from 3h following exposure with a maximal decline at 12 and 24h. Changes in the localization of NF-κB were observed with maximal nuclear translocation in germ cells at 12 and 24h. Terminal deoxynucleotidyl transferase-mediated dUTP nickend-labeling (TUNEL) assay revealed a time-dependent increase in the number of apoptotic cells. Taken together, the data illustrate induction of testicular apoptosis in adult rats following exposure to a single dose of lindane. Early activation of NF-κB in contrast to late increase in Fas expression suggests a pro-apoptotic role of NF-κB in testicular response to lindane. [Copyright &y& Elsevier]

The role played by the Fas/FasL system in the activation of apoptosis during the spermatogenesis of the spotted ray Torpedo marmorata was investigated. By immunohistochemical and western blot techniques it was demonstrated that the Fas/FasL system is amply represented during spermatogenesis of T. marmorata and it could act both via a paracrine and autocrine route: paracrine at the level of immature and mature cysts, autocrine only in mature cysts. [ABSTRACT FROM AUTHOR]

The effects of L-glutamate on activation-induced cell death (AICD) of human activated (1 μg ml−1 phytohemagglutinin plus 2 U ml−1 interleukin-2; 8 days) T lymphocytes were studied by measuring anti-CD3 monoclonal antibody (10 μg ml−1; 18 h)-induced cell apoptosis (Annexin V and propidium iodide staining).L-Glutamate (1 × 10−8–1 × 10−4 M) significantly (P0.01) inhibited AICD in a concentration-dependent manner (EC50=6.3 × 10−8 M; maximum inhibition 54.8±6.3% at 1 × 10−6 M).The L-glutamate inhibitory effect was pharmacologically characterized as mediated by group I mGlu receptors, since mGlu receptor agonists reproduced this effect. The EC50 values were: 3.2 × 10−7 M for (1S,3R)-ACPD; 4.5 × 10−8 M for quisqualate; 1.0 × 10−6 M for (S)-3,5-DHPG; 2.0 × 10−5 M for CHPG.Group I mGlu receptor antagonists inhibited the effects of quisqualate 1.0 × 10−6 M. The IC50 values calculated were: 8.7 × 10−5, 4.3 × 10−6 and 6.3 × 10−7 M for AIDA, LY 367385 and MPEP, respectively.L-Glutamate (1 × 10−6 M; 18 h) significantly (P0.05) inhibited FasL expression (40.8±11.3%) (cytofluorimetric analysis), whereas it did not affect Fas signalling.Expression of both mGlu1 and mGlu5 receptor mRNA by T lymphocytes and T-cell lines, as demonstrated by reverse transcriptase–PCR analysis, suggests that L-glutamate-mediated inhibition of AICD was exerted on T cells.These data depict a novel role for L-glutamate in the regulation of the immune response through group I mGlu receptor-mediated mechanisms.British Journal of Pharmacology (2006) 148, 760–768. doi:10.1038/sj.bjp.0706746; published online 5 June 2006 [ABSTRACT FROM AUTHOR]

Background Erythema multiforme (EM) and Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) are determined by a dysregulation of cellular immunity. Objectives To evaluate the effector role of cellular immunity and the involvement of the CD40/CD40 ligand (CD40L) system in the pathogenesis of EM and SJS/TEN. Methods Biopsy specimens from eight patients with EM and six with SJS/TEN were stained for immunohistochemical examination using the alkaline phosphatase/antialkaline phosphatase method. The monoclonal antibodies used included those to CD1a, CD4, CD8, CD40, CD40L, CD68, Fas, Fas ligand (FasL) and myeloperoxidase. Results The cellular infiltrate in both EM and SJS/TEN lesions was composed mainly of T lymphocytes and CD68+ macrophages. We also detected large amounts of neutrophils. Fas and FasL were very highly expressed in SJS and TEN, but weakly in EM. CD40 staining was strong in all tissue sections; there were numerous CD40L+ cells in SJS/TEN but much fewer in EM. Conclusions Activated T lymphocytes and macrophages, but also neutrophils, are presumably the main triggers of mucocutaneous damage in the SJS/TEN disease spectrum. The Fas/FasL system is significantly expressed in SJS/TEN lesions, but not in EM, where this apoptotic pathway presumably does not play a pivotal role in the epidermal damage. We suggest that the CD40/CD40L system may represent an important pathway of induction of SJS/TEN lesions, while in EM it would contribute to the immunoinflammation only as a second-line mechanism. [ABSTRACT FROM AUTHOR]

Failure to perform the Fas-related apoptosis pathway can account for tumor resistance both to chemotherapeutic agents and to immunological effectors. We studied the role of NK-κB in Fas-resistance, employing the Fas-sensitive human T-lymphoma HuT78 cell line and its Fas-resistant variants HuT78B1 and HuT78G9. All these cell lines expressed high levels of constitutively activated NF-κB. Pretreatment of cells with NF-κB inhibitors (PDTC, MG132, or SN50) strongly enhanced CH11-induced apoptosis in HuT78 and Hut78G9 cells, while only MG132 showed a similar potentiating effect in HuT78B1. The described synergism was significantly inhibited by pretreatment with the anti-Fas-blocking antibody ZB4 or with the pancapsase inhibitor Z-VAD-FMK, but not by capsase-8 or -9 inhibitors. Overall, these data suggest that NF-κB inhibition may restore the Fas-pathway in Fas-resistant NF-κB-overexpressing tumors. [ABSTRACT FROM AUTHOR]

SUMMARY Since in coeliac disease mucosal flattening has been suggested to result from an increased enterocyte apoptosis triggered by Fas/Fas ligand system and perforin cytolytic granules, we looked for a similar mechanism in autoimmune enteropathy. Moreover, we tried to assess whether enterocyte autoantibodies, which are the hallmark of autoimmune enteropathy, may be involved in triggering enterocyte apoptosis in this condition. Immunohistochemical staining with anti-Fas, -FasL and -perforin MoAb, and TUNEL technique were applied on endoscopic duodenal biopsies of two autoimmune enteropathy patients, two untreated coeliac patients and two biopsied controls. Cytotoxicity assays were carried out by incubating peripheral blood mononuclear cells from a healthy subject (effectors) with enterocytes primed with patient or control sera (targets). In autoimmune enteropathy a large number of enterocytes were apoptotic, as in coeliac disease, whereas neither Fas/Fas ligand or perforin expressions were up-regulated. On the other hand, antibody-dependent cellular cytotoxicity assay revealed the ability of sera from patients with autoimmune enteropathy to mediate enterocyte death through apoptosis. These results point to enterocyte autoantibody-dependent cellular cytotoxicity as the prevalent mechanism of increased enterocyte apoptosis in autoimmune enteropathy but not in coeliac disease. [ABSTRACT FROM AUTHOR]

Loss of germ cells is very common during various stages of mammalian spermatogenesis. Although cell death, particularly apoptosis, has been implicated, our understanding of the mechanisms underlying germ cell death is still limited. In order to elucidate the extent and mechanism of germ cell death, this review first covers what is known of germ cell degeneration in the normal testes of fetal, neonatal, and adult mice from electron microscopy (EM) and from terminal dUTP nick-end labeling (TUNEL) staining. The issue of whether the Fas and Fas ligand (FasL) system is involved in the induction of germ cell apoptosis in normal and damaged testes is then addressed, including consideration of both the ischemia-reperfusion model of testicular torsion and the estrogen-treated testis model of environmental endocrine disruption. Finally, this review proposes that different molecular pathways may be triggered to induce male germ cell apoptosis, depending upon the physiological and pathological states of the germ cells. [ABSTRACT FROM AUTHOR]

Survival and apoptosis are of major importance in the osteoclast life cycle. As osteoclasts have short lifespan, any alteration that prolongs their viability may cause enhanced osteoclast activity. Hence, the regulation of OC apoptosis has been recognized as a critical factor in bone remodeling. An imbalance in bone remodeling due to increased osteoclast activity leads to most adult bone diseases such as osteoporosis, rheumatoid arthritis and multiple myeloma. Therefore, manipulating osteoclast death would be a viable therapeutic approach in ameliorating bone diseases, with accelerated resorption. Over the last few decades we have witnessed the unraveling of many of the intracellular mechanisms responsible for osteoclast apoptosis. Thus, an understanding of the underlying mechanisms by which osteoclasts undergo programmed cell death and the regulators that modulate that activity will undoubtedly provide an insight into the development of pharmacological agents to treat such pathological bone diseases., Competing Interests: The authors declare that there are no conflicts of interest., (© 2019 Published by Elsevier Inc.)