Immunohistochemical analysis of Fas ligand expression in normal human tissues

Immunosuppressive Mechanisms of Malignant Gliomas: Parallels at Non-CNS Sites

The central nervous system (CNS) possesses powerful local and global immunosuppressive capabilities that modulate unwanted inflammatory reactions in nervous tissue. These same immune-modulatory mechanisms are also co-opted by malignant brain tumors and pose a formidable challenge to brain tumor immunotherapy. Routes by which malignant gliomas coordinate immunosuppression include the mechanical and functional barriers of the CNS; immunosuppressive cytokines and catabolites; immune checkpoint molecules; tumor-infiltrating immune cells; and suppressor immune cells. The challenges to overcoming tumor-induced immunosuppression, however, are not unique to the brain, and several analogous immunosuppressive mechanisms also exist for primary tumors outside of the CNS. Ultimately, the immune responses in the CNS are linked and complementary to immune processes in the periphery, and advances in tumor immunotherapy in peripheral sites may therefore illuminate novel approaches to brain tumor immunotherapy, and vice versa.

Gonadal steroids modulate Fas-induced apoptosis of lactotropes and somatotropes

We have previously reported that Fas activation induces apoptosis of anterior pituitary cells from rats at proestrus but not at diestrus and in an estrogen-dependent manner. In this study, we evaluated the effect of Fas activation on apoptosis of lactotropes and somatotropes during the estrous cycle and explored the action of gonadal steroids on Fas-induced apoptosis. Also, we studied whether changes in Fas expression are involved in the apoptotic response of anterior pituitary cells. Fas activation increased the percentage of TUNEL-positive lactotropes and somatotropes at proestrus but not at diestrus. FasL triggered apoptosis of somatotropes only when cells from ovariectomized rats were cultured in the presence of 17 β-estradiol (E2). Progesterone (P4) blocked the apoptotic action of the Fas/FasL system in lactotropes and somatotropes incubated with E2. Both E2 and P4 increased the percentage of cells expressing Fas at the cell membrane. Our results show that Fas activation induces apoptosis of lactotropes and somatotropes at proestrus but not at diestrus. Gonadal steroids may be involved in the apoptotic response of lactotropes and somatotropes, suggesting that Fas activation is implicated in the renewal of these pituitary subpopulations during the estrous cycle. The effect of gonadal steroids on Fas expression may be only partially involved in regulation of the Fas/FasL apoptotic pathway in the anterior pituitary gland.

The expression of p53, bcl-2, bax, fas and fasL in the primary tumour and lymph node metastases of breast cancer

PURPOSE. It is unknown to what extent lymph node metastases differ from primary tumours of breast cancer. Our aim was to investigate the similarity between primary breast tumours and the matching lymph node metastases in 59 breast cancer patients. EXPERIMENTAL DESIGN. Immunohistochemical stainings of p53, bax, bc-l2, fas and fasL were performed in primary tumours and the parallel lymph node metastases. RESULTS. When using a cut point of 10%, the concordance between primary tumours and parallel lymph node metastases in the expression of p53 was 85%, bcl-2 79%, bax 69%, fas 59% and fasL 43%. In most tumours the staining status of p53, bcl-2 and bax in the primary tumour and the corresponding lymph node did not change more than 20%. However, these variables could fluctuate in both directions. In 15-25% of the cases, nodal expression was more than 20% lower than in the primary tumours, while in 10-17% of the cases, nodal expression was more than 20% higher than in the primary tumours. In half of the tumours, fas status did not change. Most fasL positive tumours lost positivity in the lymph node metastases or showed positively staining cancer cells only in the peripheral region of the node. A phenotype analysis of combined information of tumour fas/tumour fasL/nodal fas/nodal fasL expression (+/ - ) was assessed. The most frequently observed phenotype was tumour fas - /tumour fasL + /nodal fas - /nodal fasL- (22% of the tumours), although almost all combinations were seen. CONCLUSIONS. The expression of p53, bax, bcl - 2, fas and fasL is not maintained in the matching lymph node metastases of breast cancer. Large studies comparing the expression of relevant tumour biology factors in primary tumours and parallel lymph node metastases and their impact on therapy outcome, especially in the adjuvant setting, are warranted.

Abundant Fas expression by gastrointestinal stromal tumours may serve as a therapeutic target for MegaFasL

Although the tyrosine kinase inhibitor imatinib has been shown to be an active agent in patients with gastrointestinal stromal tumours (GIST), complete remissions are almost never seen and most patients finally experience disease progression during their course of treatment. An alternative therapeutic option is to target death receptors such as Fas. We showed that a panel of imatinib-sensitive (GIST882) and imatinib-resistant (GIST48, GIST430 and GIST430K-) cell lines expressed Fas. MegaFasL, a recently developed hexameric form of soluble Fas ligand (FasL), appeared to be an active apoptosis-inducing agent in these cell lines. Moreover, MegaFasL potentiated the apoptotic effects of imatinib. Immunohistochemical evaluations, in 45 primary GISTs, underscored the relevance of the Fas pathway: Fas was expressed in all GISTs and was expressed strongly in 93%, whereas FasL was expressed at moderate and strong levels in 35 and 53% of GISTs, respectively. Fas and FasL expression were positively correlated in these primary GISTs, but there was no association between Fas or FasL expression and primary site, histological subtype, tumour size, mitotic index, risk classification, and KIT mutation status. The abundant immunohistochemical Fas and FasL expression were corroborated by western blot analysis. In conclusion, our data implicate Fas as a potential therapeutic target in GIST.

Is benign prostatic hyperplasia (BPH) an immune inflammatory disease?

OBJECTIVES

Chronic inflammation has been documented for years in benign prostatic hyperplasia (BPH), but only now has it become evident as a major factor in disease progression. This review highlights the immunologic key features of chronic inflammation in BPH and the present interpretation of these changes in the development and progression of BPH.

RESULTS

Almost all BPH specimens show inflammatory infiltrates at histologic examination, but correlation to bacterial or other foreign antigens has not been established. Recognition of prostate secretion products by autoreactive T cells and animal models on experimental prostatitis demonstrate an autoimmune component to chronic inflammation. The infiltrate consists predominantly of chronically activated CD4(+) T lymphocytes, which are permanently recruited to prostate tissue via elevated expression of interleukin 15 (IL-15) and interferon gamma (IFN-gamma), proinflammatory cytokines produced by smooth muscle and T cells, respectively. With the appearance of infiltrates, T cell-derived cytokine production of IFN-gamma, IL-2, and transforming growth factor beta increases, the former two ultimately reaching 10-fold and the latter 2-fold higher levels in fully developed BPH than in normal prostates. As "mature" BPH nodules develop, IL-4 and IL-13 expression increases >2-fold, corresponding to a T-helper (Th)0/Th2 cytokine pattern. Dysregulation of the immune response in BPH may occur via elevated expression of proinflammatory IL-17, which stimulates a multifold production of IL-6 and IL-8, key executors of stromal growth in BPH.

CONCLUSIONS

These data strongly suggest that BPH is an immune inflammatory disease. Unravelling the specific nature of immune dysregulation may help design novel drugs with these specific targets in mind.

Expression of Fas ligand and CTLA4 in adenoids has a predictive value for allergic rhinitis development in children

BACKGROUND

The balance of CD28/CTLA4-derived signals and Fas-dependent apoptosis activity is determined by the peripheral defense mechanisms and might play a role in the pathogenesis of allergy.

OBJECTIVES

The aim of the study was to investigate the expression of costimulatory and pro- and antiapoptotic molecules in adenoid T cells of children suffering from allergic rhinitis and to find out which of these molecules have a predictive value in the development of allergic rhinitis.

METHODS

The adenoids of 60 children, removed because of nasal obstruction, chronic rhinitis and recurrent respiratory infection, were evaluated. Patients were divided into two groups: group 1, suffering from chronic allergic rhinitis, and group 2, suffering from chronic rhinitis, where no specific IgE was detected, including children with a positive family history of allergy (group 2a) and children with neither a personal nor a family history of allergy (group 2b). For immunohistochemical stainings anti-CD3, anti-CD19, anti-CD4, anti-CD8, anti-CD25, anti-CD28, anti-CTLA4 (CD152), anti-bcl-2, anti-Fas, and anti-FasL antibodies were used. The number of cells expressing these molecules was identified in adenoid interfollicular spaces. The results were then analyzed in allergic and nonallergic children. During a 24-month follow-up children were re-examined for allergy and results were compared to previous immunohistochemical evaluations.

RESULTS

The expression of CD4, CD25, CD28, FasL, and CTLA4 was significantly increased in group 1 compared to group 2 (p < 0.05). However, the discriminant analysis confirmed that only CTLA4 and FasL expression fully discriminated allergic subjects from the others. During a 24-month period of observation 8 children from group 2a were also diagnosed with allergic rhinitis. All of them, especially those sensitized to mites, had an increased number of FasL+ and CTLA4+ in previously removed adenoids.

CONCLUSION

An increased number of cells with intracellular expression of FasL and CTLA4, in interfollicular spaces of adenoids, seems to be a predictive factor of the development of allergic rhinitis.

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

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.

Fas Ligand Expression and Its Correlation with Apoptosis and Proliferation in Lobund-Wistar Prostate Carcinomas

OBJECTIVE

The Fas (CD95) interaction with its receptor Fas ligand (FasL) is one of the main mechanisms of cell apoptosis. High expression of FasL has been consistently observed in a variety of human cancers. In this study, we evaluated FasL and its relationship with apoptosis and proliferation in Lobund-Wistar (L-W) cancers. The L-W rat strain develops spontaneous and induced adenocarcinomas in the anterior prostate and seminal vesicles. Although FasL expression has been observed in a subset of human prostate carcinomas, this multistage model allowed in vivo evaluation of subclones of malignant cells with a single genetic susceptibility.

METHODS

Apoptosis was evaluated in spontaneous, induced and transplanted tumors as well as metastasis using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique and transmission electron microscopy. Proliferating cell nuclear antigen (PCNA) and FasL expression were detected using immunohistochemistry and analyzed according to the number of positive cells and intensity of staining using a semiquantitive method.

RESULTS

Apoptotic indexes were significantly higher in spontaneous tumors compared to induced (p < 0.008), transplanted tumors (p < 0.0112) and metastases (p < 0.009). TUNEL-positive cells were frequently observed in the leukocytic infiltrate of the stroma in transplanted carcinomas and metastases. These findings were confirmed by electron microscopy. FasL expression was not uniformly localized in L-W carcinomas and its highest expression was observed in transplanted tumors and metastasis (p < 0.005). Moreover, PCNA indices were directly correlated with cancers showing high FasL total scores (Hscores).

CONCLUSIONS

In this model, high FasL expression was associated with cells displaying low apoptotic indexes and high PCNA index. Therefore, analysis of FasL may have clinical relevance in detecting the malignant potential of prostate cancers.

Estrogens up-regulate the Fas/FasL apoptotic pathway in lactotropes

The Fas/FasL system provides the major apoptotic mechanism for many cell types, participating in cell turnover in hormone-dependent tissues. In the present study, we localized both Fas and FasL in anterior pituitary cells, mainly in lactotropes and somatotropes. The percentage of anterior pituitary cells showing immunoreactivity for Fas or FasL was higher in cells from rats killed in proestrus than in diestrus. Also, the proportion of pituitary cells from ovariectomized (OVX) rats expressing Fas or FasL increased in the presence of 17beta-estradiol (10(-9) M). This steroid increased the percentage of lactotropes with immunoreactivity for Fas or FasL and the percentage of somatotropes expressing Fas. Activation of Fas by an agonist anti-Fas antibody (Mab-Fas) decreased the vi-ability-3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT assay)-of anterior pituitary cells from OVX rats cultured in the presence of 17beta-estradiol. Also, membrane-bound FasL decreased cell viability-[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay (MTS assay)-only when anterior pituitary cells from OVX rats were incubated with 17beta-estradiol. Moreover, FasL increased the percentage of hypodiploid anterior pituitary cells (flow cytometry). Mab-Fas increased the percentage of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL)-positive pituitary cells and lactotropes from OVX rats only when cells were incubated in the presence of 17beta-estradiol. Also, Mab-Fas triggered apoptosis of anterior pituitary cells from rats killed at proestrus but not at diestrus. Our results show that 17beta-estradiol up-regulates the expression of the Fas/FasL system in anterior pituitary cells and increases Fas-induced apoptosis in lactotropes, suggesting that Fas-induced apoptosis could be involved in the pituitary cell renewal during the estrous cycle.

Testicular germ cell tumours: the paradigm of chemo-sensitive solid tumours

Testicular germ cell tumours (TGCTs) are the most frequent solid malignant tumour in men 20-40 years of age and the most frequent cause of death from solid tumours in this age group. Up to 50% of the patients suffer from metastatic disease at diagnosis. The majority of metastatic testicular cancer patients, in contrast to most other metastatic solid tumours, can be cured with highly effective cisplatin-based chemotherapy. From a genetic point of view, almost all TGCTs in contrast to solid tumours are characterised by the presence of wild type p53. High p53 expression levels are associated with elevated Mdm2 levels and a loss of p21(Waf1/Cip1) expression suggesting a changed functionality of p53. Expression levels of other proteins involved in the regulation of cell cycle progression indicate a deregulated G1-S phase checkpoint in TGCTs. After cisplatin-induced DNA damage, the increasing levels of p53 lead to the trans-activation of a number of genes but not of p21(Waf1/Cip1), preferentially directing TGCT cells into apoptosis or programmed cell death, both via the mitochondrial and the death receptor apoptosis pathways. The sensitivity of TGCTs to chemotherapeutic drugs may lay in the susceptibility of germ cells to apoptosis. Taken together, this provides TGCT as a tumour type model to investigate and understand the molecular determinants of chemotherapy sensitivity of solid tumours. This review aims to summarise the current knowledge on the biological basis of cisplatin-induced apoptosis and response to chemotherapy in TGCTs.

Fas ligand in the uterus of the non-pregnant mouse induces apoptosis of CD4+ T cells

The role of FasL in the reproductive tissues of the non-pregnant mouse may be the induction of apoptosis of activated T cells for the prevention of unwanted inflammatory responses secondary to infection. This study was undertaken to identify cell and tissue types that typically express FasL in the uterus and oviduct of the mouse and to establish whether FasL on the surface of these cells was able to induce T cell apoptosis. FasL in the mouse uterus and oviduct was demonstrated using three independent methods: RT-PCR, Western blot and immunocytochemistry. The protein was present in the epithelial and mesenchymal cells of the uterus and showed a granular pattern in the apical epithelial portion. Although this suggests the presence of vesicles, surface expression was also detected by flow cytometry of isolated uterine cells. Exogenous administration of estradiol and progesterone had no significant effect on the expression and localization of FasL. The ability of uterine cells to induce FasL-dependent apoptosis of activated CD4+T cells was examined by incubation of phytohemagglutinin-treated T cells with cultured uterine cells. TUNEL and flow cytometric analyses showed that CD4+T cells experienced apoptosis after 5h of co-incubation. Neutralizing antibodies inhibited apoptosis demonstrating that a biologically active FasL is present in the reproductive tissues of the mouse. Results indicate that FasL is a biologically active molecule present in epithelial and mesenchymal cells of the uterus and the oviduct of the non-pregnant mouse that might restrain local immune response by induction of apoptosis of CD4+T lymphocytes.

Fas Ligand Expression Following Normothermic Liver Ischemia-Reperfusion

BACKGROUND

The aim of this study was to evaluate the role of the pro-apoptotic molecule Fas Ligand (FasL) in 120 min normothermic ischemia-reperfusion (I-R) induced apoptosis in rat liver treated or not with Z-Asp-cmk caspase inhibitor.

MATERIALS AND METHODS

Rats were divided into two groups: group 1, control, PBS administration; group 2, Z-Asp-cmk treatment. Z-Asp-cmk was injected intravenously, 2 min before induction of 120 min of normothermic liver ischemia. Immunohistochemical detection of apoptotic liver cells was carried out using the TUNEL method. Fas and FasL expression were measured by qualitative reverse transcription polymerase chain reaction (RT-PCR), Northern and western blot, and by immunofluorescence labeling, in ischemic and non-ischemic liver lobes at different times after reperfusion.

RESULTS

FasL mRNA and protein expression were increased in ischemic liver, while Fas receptor mRNA levels remained unchanged. Pre-treatment of rats with Z-Asp-cmk caspase inhibitor reduced liver apoptosis, but did not modify FasL mRNA levels.

CONCLUSIONS

These results suggest that the pro-apoptotic molecule FasL is involved in the induction of liver apoptosis following I-R.

FAS and FAS-L expression by tumor cells and lymphocytes in breast carcinomas and their lymph node metastases

FAS receptor (FAS, CD95) and FAS ligand (FAS-L, CD95-L) are complementary members of a particular apoptotic pathway that plays a major role in immune regulation. The activation of FAS-L may trigger cytotoxic mechanisms leading to the death of FAS-expressing cells. Tumor cells and tumor-infiltrating lymphocytes (TIL) may express FAS and FAS-L in various proportions, and their interplay may affect tumor behavior. In the present study, we explored the expression of FAS and FAS-L in 28 mammary carcinomas (19 ductal and 9 lobular) and in their lymph node metastases. The expression of these mediators in immunostained sections was graded and evaluated comparatively between normal and neoplastic mammary epithelium, between tumor cells and TILs, and between mammary carcinoma cells and their lymph node metastases. We demonstrated the coexpression of FAS and FAS-L by breast carcinoma cells and TIL, with FAS expressed more strongly by normal epithelial cells and TIL than tumor cells. FAS-L was better stained on tumor cells than on TIL. There was equal or greater expression of FAS and FAS-L in the primary tumors and their TIL than in the metastatic counterparts. Comparing the expression of FAS with that of FAS-L, we recorded FAS equal or stronger than FAS-L in the primary mammary tumors and the reversal of their expression, FAS-L greater than FAS in the lymph node metastases. These results are consistent with reports of studies with other tumors, suggesting that the upregulated FAS-L indicates an increased ability of tumor cells to induce apoptosis in TIL and in the normal tissues invaded. However, it is understood that the FAS/FAS-L system, although essential for apoptosis, is only a contributing factor to the complex process of tumor invasion and antitumor defense.

Tissue distribution of the death ligand TRAIL and its receptors

Recombinant human (rh) TNF-related apoptosis-inducing ligand (TRAIL) harbors potential as an anticancer agent. RhTRAIL induces apoptosis via the TRAIL receptors TRAIL-R1 and TRAIL-R2 in tumors and is non-toxic to nonhuman primates. Because limited data are available about TRAIL receptor distribution, we performed an immunohistochemical (IHC) analysis of the expression of TRAIL-R1, TRAIL-R2, the anti-apoptotic TRAIL receptor TRAIL-R3, and TRAIL in normal human and chimpanzee tissues. In humans, hepatocytes stained positive for TRAIL and TRAIL receptors and bile duct epithelium for TRAIL, TRAIL-R1, and TRAIL-R3. In brains, neurons expressed TRAIL-R1, TRAIL-R2, TRAIL-R3 but no TRAIL. In kidneys, TRAIL-R3 was negative, tubuli contorti expressed TRAIL-R1, TRAIL-R2, and TRAIL, and cells in Henle's loop expressed only TRAIL-R2. Heart myocytes showed positivity for all proteins studied. In colon, TRAIL-R1, TRAIL-R2, and TRAIL were present. Germ and Leydig cells were positive for all proteins studied. Endothelium in liver, heart, kidney, and testis lacked TRAIL-R1 and TRAIL-R2. In alveolar septa and bronchial epithelium TRAIL-R2 was expressed, brain vascular endothelium expressed TRAIL-R2 and TRAIL-R3, and in heart vascular endothelium only TRAIL-R3 was present. Only a few differences were observed between human and chimpanzee liver, brain, and kidney. In contrast to human, chimpanzee bile duct epithelium lacked TRAIL, TRAIL-R1, and TRAIL-R3, lung and colon showed no TRAIL or its receptors, TRAIL-R3 was absent in germ and Leydig cells, and vascular endothelium showed only TRAIL-R2 expression in the brain. In conclusion, comparable expression of TRAIL and TRAIL receptors was observed in human and chimpanzee tissues. Lack of liver toxicity in chimpanzees after rhTRAIL administration despite TRAIL-R1 and TRAIL-R2 expression is reassuring for rhTRAIL application in humans.

Transforming growth factor-beta1 induced hepatocyte apoptosis--a possible mechanism for growth of colorectal liver metastasis

The mechanisms of colonization and growth of metastatic liver tumors from colorectal cancers remain obscure. Forty-three resected colorectal metastatic liver tumors with surrounding livers were evaluated for apoptotic index (AI), proliferation index (PI), and immunohistochemical expressions of TGF-beta1. TGF-beta receptor II, Fas, and Fas-ligand. All the parameters were significantly higher in the peri-tumoral livers than in the tumors with the exception of PI, which was significantly high in tumors. Enhanced TGF-beta1 expression was noticed at the interface between the metastatic tumor and the adjacent liver parenchyma. The AIs of hepatocytes in the TGF-beta1-positive areas (8.7 +/- 7.5%, n = 43) were significantly higher when compared with those in the TGF-beta1-negative areas (2.4 +/- 4.5%, n = 42) (p < 0.001). However, the same kind of correlation could not be found in metastatic tumors. The enhanced expression of TGF-beta1 and hepatocyte apoptosis in the peri-tumoral liver parenchyma may suggest that TGF-beta1 plays a substantial role in the development of colorectal liver metastasis.

Placental Fas and Fas Ligand Expression in Normal Early, Term and Molar Pregnancy

To clarify the Fas and Fas-ligand status of normal and molar trophoblast, the expression of Fas and FasL by placental trophoblast populations in partial and complete hydatidiform moles was compared with that in normal first trimester and term pregnancies using an avidin-biotin peroxidase technique on frozen and formalin-fixed paraffin-embedded placental tissues with both monoclonal and polyclonal antibodies. The TUNEL technique was used to detect apoptotic cells in the same tissues. The immunoreactivity for Fas and Fas-ligand was comparable with both monoclonal and polyclonal antibodies on frozen as well as paraffin-embedded sections. In normal early and molar pregnancy there was strong FasL expression by villous cytotrophoblast and syncytiotrophoblast. However, there were significant differences in FasL expression by trophoblast subpopulations in both early and term normal pregnancy and between the same trophoblast subpopulation at different gestations, with FasL staining generally being weaker at term. Strong FasL staining by cytotrophoblast cells in the distal parts of cell columns contrasted with unstained cytotrophoblast in the proximal part of columns. Distinct trophoblast subpopulations in partial hydatidiform mole also differentially expressed FasL with reduced FasL expression in proliferating syncytiotrophoblast. In contrast there was no differential FasL expression in complete hydatidiform mole, all trophoblast subpopulations strongly expressing FasL. Unlike the differential expression of FasL there were no differences in Fas expression by trophoblast populations in normal early or term placental tissues. Fas expression was reduced in villous cytotrophoblast at term. Differential expression of Fas by different trophoblast subpopulations was noted in partial and complete hydatidiform mole. In complete mole villous cytotrophoblast and syncytiotrophoblast stained strongly compared with proliferating trophoblast. Using TUNEL labelling apoptosis was rarely detected in placental trophoblast. Differential Fas and FasL expression by trophoblast subpopulations in normal and pathological pregnancy does not appear to be related to apoptosis of trophoblast.

Altered Distribution of Metaplastic Paneth, Gastrin and Pancreatic Acinar Cells in Atrophic Gastritic Mucosa with Endocrine Cell Lesions

The mechanism of progression from gastric endocrine cell hyperplasias (ECHs) to carcinoid tumor (GCT) is still unknown. In these lesions, the distribution of metaplastic Paneth, gastrin and pancreatic acinar cells developing due to consequences of corporal mucosal atrophy has not been investigated in detail. In this study, 33 gastric endoscopic biopsies with endocrine cell lesions were examined. In all cases except 6 with solitary GCT, complete-type (small intestine) intestinal metaplasia (IM) with Paneth cells was observed. The density of lysozyme-positive Paneth cells in IMs in cases with GCTs was less than those in ECH alone. The density of gastrin-positive cells in IMs and average number of micronodules of ECHs were similar. Pancreatic acinar metaplasia (PAM) was observed in 6 cases of GCTs with ECH. The size of GCTs with ECH was smaller than those without ECH. By image analysis, the percentage of Ki67 (MIB-1, proliferation marker) expressing cells of GCTs with ECH was 5.1+/-0.6%, and GCT without ECH 7.8+/-1%. Our results indicate that few Paneth cells and many PAMs in atrophic corporal mucosa are seen more frequently in cases of GCTs with ECH, compared to those in ECH alone. Gastrin-positive cells in the corporal IM may stimulate enterochromaffin-like (ECL) cells, which may induce hyperplasia, dysplasia or neoplasia by augmenting the effects of hypergastrinemia through a paracrine mechanism on local gastrin-sensitive cells.

Evaluation of CD25, CD152, Fas-ligand expression in the adenoids of allergic and non-allergic children: a pilot study

BACKGROUND

The nasal mucosa is the initial site in the upper airways of the host defence against antigen challenge. The lymphatic structure closest to the nasal mucosa is the adenoid. Apoptotic cell death is an important mechanism for maintaining homeostasis in the immune system, and for regulating the fates of lymphocytes following encounters with self and foreign antigens. This process regulates the population of lymphocytes in peripheral lymphoid organs following exposure to various allergens.

OBJECTIVES

The objectives of this study were to find evidence for the hypothesis that the development of allergic illness depends on allergic sensitisation in the adenoid.

METHODS

In this study, cellular infiltrates in the adenoids of 12 allergic and 13 non-allergic children were evaluated. The number of positive cells for CD4, CD8, CD25, CD152, and Fas-ligand were determined using immunohistochemical stainings and imaging analysis techniques.

RESULTS

There was found a higher expression of CD25, CD152 and Fas-ligand in small, activated lymphocytes, especially in the interfollicular area of allergic patients than in the control group. The expression of FasL in activated lymphocytes, as well as in macrophages, was observed. Statistical analysis has shown a significant correlation between expression of CD152 and allergic disease, and a more intense correlation between CD25, CD152 and Fas-ligand and allergic disease. There was no statistically important divergence in the CD4/CD8 ratio in different samples.

Germ cell apoptosis in autoimmune orchitis: involvement of the Fas-FasL system

PROBLEM

The aim of this study was to determine the mechanism of germ cell death in experimental autoimmune orchitis (EAO) and the involvement of the Fas-FasL system in this process.

METHOD OF STUDY

The EAO was induced in rats by immunization with testis homogenate and adjuvants. Apoptosis was studied by light microscopy, in situ end labeling of apoptotic DNA and DNA fragmentation techniques. Fas, FasL and caspase 3 expression was detected by immunohistochemistry.

RESULTS

In rats with orchitis the number of Fas+ and FasL+ apoptotic germ cells increased from day 50, when the lesion develops, to 150 days, and correlates with the degree of testicular damage. Most spermatocytes expressing Fas were apoptotic. Many Fas+ germ cells were also immunoreactive for FasL. Moreover, these cells also expressed caspase 3.

CONCLUSIONS

In rats with EAO germ cell death occurs through an apoptotic mechanism preceding germ cell sloughing. Immunohistochemical data suggest that the Fas-FasL system mediates germ cell apoptosis in an autocrine and/or paracrine way.

HPV subtypes and immunological parameters of cervical cancer in Iceland during two time periods, 1958-1960 and 1995-1996

OBJECTIVE

Cervical cancer is a disease caused in part by an infection with an oncogenic subtype of human papillomavirus (HPV). In this study we analysed all cervical cancer samples diagnosed in Iceland during two periods, 1958-1960 and 1995-1996, and asked whether significant changes in viral or immunological parameters had occurred over a period that spanned both significant changes in sexual attitude and the implementation of organized screening for cervical cancer.

METHODS

Samples from 47 patients (46 squamous cell carcinomas (SCC) and 1 adenosquamous carcinoma (ASC)) in the first period and 30 patients (20 SCC, 4 ASC, and 6 adenocarcinomas (AC)) in the later period were analysed for viral subtype and expression of Fas, FasL, MHC class I, p53 and apoptosis.

RESULTS

AC and ASC are proportionately much more common today than 40 years ago (30% vs 2%). The distribution of HPV in cervical cancer is similar in both periods, with HPV16 found in 75% and HPV18 in 13% of cases. Other HPV types found were 31,33,45, and 59. No significant differences were found in the immunological profiles of tumors from the two periods except that a higher fraction of SCC in the later period stained positive for FasL. When SCC are compared with AC/ASC, the latter have less expression of MHC class I, less expression of Fas, and stronger FasL expression.

CONCLUSIONS

AC/ASC tumors show some immunological features that suggest that they are more resistant to immune attack than SCC.

Bax, Bcl-2, fas and Fas-L antigen expression in human seminoma: correlation with the apoptotic index

Apoptosis plays a crucial role in the regulation of spermatogenesis in male germ cells and is, at least in part, modulated by Bcl-2, Bax, and the Fas pathway. Seminomas have a favourable outcome and respond to radio-/chemotherapy with an increased rate of apoptosis. The expression of Bax, Bcl-2, Fas and Fas-ligand (Fas-L) in human seminoma was evaluated and correlated with the apoptotic index. Twenty-nine classical seminomas were examined by immunohistochemistry and Western blotting using antibodies against Bax, Bcl-2, Fas and Fas-L. Apoptosis was detected by in-situ end-labeling of fragmented DNA and the apoptotic index (AI) was determined. Expression of Fas was found in 26 (89.7%) of Fas-L in 24 seminomas (82.2%); none of the tumours expressed Bcl-2. No correlation between the AI and Fas, Fas-L or Bcl-2 expression was found. Bax was demonstrated in 20/29 tumours (69%). Bax-positive tumours showed an increased AI of 4.75 +/- 2.38% in contrast to 2.60 +/- 1.23% of the Bax-negative tumours (P = 0.002). The number of Bax-positive tumour cells and apoptotic cells revealed a significant correlation using chi2-test (P = 0.04) and linear regression (r = 0.54, P = 0.001). Therefore, Bax seems to play a determinant role in the modulation of apoptosis in human seminoma that may be linked to a favourable outcome.

The apoptotic profile of human cumulus cells changes with patient age and after exposure to sperm but not in relation to oocyte maturity

OBJECTIVE

To determine the expression of apoptosis-associated molecules on cumulus cells removed from individual oocytes of different maturity, inseminated oocytes and to investigate the possibility of an age-dependent expression.

DESIGN

Analysis of apoptosis in cumulus cells isolated from oocytes of different stages of maturity.

SETTING

Assisted reproductive technology program of the Birmingham Women's Hospital, Birmingham, UK.

PATIENT(S)

Patients undergoing intracytoplasmic sperm injection or IVF cycles.

MAIN OUTCOME MEASURE(S)

Percentage of positive cumulus cells when assessed for nuclear DNA damage using the terminal deoxyuridine nucleotide end-labeling assay or stained with antibodies [Fas, Fas ligand, the antiapoptotic protein Bcl-xl, and the RNA-binding protein (TIAR)].

RESULT(S)

Cumulus cells collected from mature oocytes showed no significant difference in the percentage of apoptotic markers compared to those recovered from immature oocytes, whereas those from patients >/=38 years differed significantly. When cumulus cells were exposed to sperm the levels of apoptotic markers altered significantly from those not exposed to sperm.

CONCLUSION(S)

The results show that the cumulus cells of human oocytes are equipped with a mechanism to undergo apoptosis and that patient age and the exposure of cumulus cells to sperm can alter their profiles of apoptotic markers.

Expression of CD95 (Fas) in sun-exposed human skin and cutaneous carcinomas

BACKGROUND

Carcinomas of the skin are by far the most common human malignancies. Continuous exposure to ultraviolet (UV) light facilitates the development of precancerous lesions (actinic keratosis [AK]) that may progress to invasive squamous carcinomas. Apoptosis, triggered by the activation of CD95 (Fas), is one of the most important defense mechanisms against UV light-induced carcinogenesis in experimental models, but the dynamics of CD95 expression in patients with sun-induced lesions are largely unknown.

METHODS

The authors studied the expression of CD95 (Fas) in biopsy samples of normal skin (not exposed to sun) and compared it with chronically sun-exposed skin (as evidenced by solar elastosis), AK, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), and keratoacanthomas (KA).

RESULTS

Normal skin keratinocytes expressed CD95 in cytoplasmic membranes and intercellular bridges in the basal layer. In chronically sun-exposed keratinocytes (solar elastosis, no evidence of dysplasia), CD95 expression was up-regulated and was observed throughout the entire thickness of the epidermis. However, in actinic keratosis there was a complete absence of Fas in approximately two-thirds of the cases (8 of 12). In invasive SCC, CD95 was expressed focally and weakly only at the sites of contact with stromal lymphocytes. Keratoacanthomas consistently expressed CD95 at the interface with the inflammatory cells. No staining was observed in BCC.

CONCLUSIONS

CD95 (Fas) up-regulation in chronically sun-exposed keratinocytes indicates an important role in the control of sun-induced damage. Further sun exposure results, however, in significant down-regulation of this defense mechanism, proportional to the degree of dysplasia.

Inverse relation of Fas-ligand and tumor-infiltrating lymphocytes in angiosarcoma: indications of apoptotic tumor counterattack

Fas and Fas-L regulate immune responses through the induction of cell death. Fas-L is commonly expressed in activated immune cells and in the endothelium. In the latter it contributes to the inhibition of transvascular cell migration by the induction of apoptosis in Fas-bearing lymphocytes. Here we investigated whether the Fas/Fas-L system may regulate lymphocyte invasion into angiosarcomas. Fas and Fas-L expression was quantitatively determined in different grade angiosarcomas (n = 40) and related to the number of extravasated tumor-infiltrating lymphocytes (TILs). Fas expression was detected in < 50% of the cases. In positive tumors both the number of Fas-positive cells and the staining intensity were highly variable and did not correlate with the number of TILs, the mean time of survival, and the histopathological tumor grade. By contrast, Fas-L expression was detected in >70% of the cases and the relative numbers of Fas-L-positive cells correlated inversely with the numbers of CD3- and CD8-positive TILs (P < or = 0.004). The survival times of patients with high Fas-L-expressing angiosarcomas were significantly reduced as compared to patients with low Fas-L-expressing tumors. Our results show that angiosarcomas with low Fas-L expression are characterized by numerous TILs, whereas sarcomas with high Fas-L expression show significantly reduced numbers of TILs. These results suggest that the Fas/Fas-L system may repress TIL invasion into angiosarcoma and by this may contribute to the evasion of the anti-tumor immune surveillance of angiosarcoma in the course of an apoptotic tumor counterattack mechanism.

Differential and mutually exclusive expression of CD95 and CD95 ligand in epithelia of normal pancreas and chronic pancreatitis

Acinar regression in chronic pancreatitis may be due to immune attack in parenchymal areas neoexpressing HLA-DR molecules. CD4+Th1 cytotoxic T cells induce apoptosis of their targets via oligomerizing CD95 (APO-1/Fas) death receptors on target cells by their CD95 ligand (CD95L). We determined the expression of CD95 and CD95L in epithelia of normal and chronically inflamed pancreatic tissues. We applied RT-PCR and Western blotting for CD95L expression profiles, serial frozen section immunohistochemistry to detect CD95, CD95L, and HLA-DR molecules, CD3, CD4, CD11c, and S-100 protein (S100p). Normal pancreases and chronic pancreatitis contain CD95L message and protein. Immunohistochemistry revealed a mutually exclusive expression of CD95 and CD95L. Physiologically, acini were CD95-/CD95L+, ducts were CD95-/CD95L-, and islets were CD95-/CD95L+. In areas of lymphohistiocytic infiltration, mainly consisting of CD3+CD4+ T cells and CD11c+, CD4+/-, S100p+ interstitial dendritic cells, and in areas of initial fibrosis, acini and ducts were HLA-DR+, acini CD95+/CD95L-, and ducts CD95+/CD95L-. Islet cells were CD95-/CD95L+ in both conditions. IFNgamma levels in protein lysates, as measured by an immunoassay, were significantly higher in chronic pancreatitis than in normal pancreas (p < 0.0003). In vitro, IFNgamma down-modulated CD95L message and protein in ASPC1 and BxPc3 pancreatic carcinoma cells. In conclusion, pancreatic epithelia differentially express CD95 and CD95L in a mutually exclusive manner. In chronic pancreatitis the CD95-/CD95L+ status is conserved in islet cells even in the vicinity of lymphohistiocytic infiltrates, whereas it is lost in acini coexpressing HLA-DR. As a potential consequence, and possibly triggered by local release of IFNgamma, CD4-Th1 cells may cognately interact with and successfully attack exocrine cells by triggering CD95 on their target without being killed by epithelial, CD95L-mediated, counterattack.