Asparaginase-like protein 1 expression in curettage independently predicts lymph node metastasis in endometrial carcinoma: a multicentre study

OBJECTIVE

Correct preoperative identification of high-risk patients is important to optimise surgical treatment and improve survival. We wanted to explore if asparaginase-like protein 1 (ASRGL1) expression in curettage could predict lymph node metastases and poor outcome, potentially improving preoperative risk stratification.

DESIGN

Multicentre study.

SETTING

Ten hospitals in Norway, Sweden and Belgium.

POPULATION

Women diagnosed with endometrial carcinoma.

METHODS

ASRGL1 expression in curettage specimens from 1144 women was determined by immunohistochemistry.

MAIN OUTCOME MEASURES

ASRGL1 status related to disease-specific survival, lymph node status, preoperative imaging parameters and clinicopathological data.

RESULTS

ASRGL1 expression had independent prognostic value in multivariate survival analyses, both in the whole patient population (hazard ratio (HR) 1.63, 95% CI 1.11-2.37, P = 0.012) and in the low-risk curettage histology subgroup (HR 2.54, 95% CI 1.44-4.47, P = 0.001). Lymph node metastases were more frequent in women with low expression of ASRGL1 compared with women with high ASRGL1 levels (23% versus 10%, P < 0.001), and low ASRGL1 level was found to independently predict lymph node metastases (odds ratio 2.07, 95% CI 1.27-3.38, P = 0.003).

CONCLUSIONS

Low expression of ASRGL1 in curettage independently predicts lymph node metastases and poor disease-specific survival.

TWEETABLE ABSTRACT

Low ASRGL1 expression in curettage predicts lymph node metastasis and poor survival in endometrial carcinoma.

Placental inflammation in pre-eclampsia by Nod-like receptor protein (NLRP)3 inflammasome activation in trophoblasts

Pre-eclampsia is associated with increased levels of cholesterol and uric acid and an inflamed placenta expressing danger-sensing pattern recognition receptors (PRRs). Crystalline cholesterol and uric acid activate the PRR Nod-like receptor protein (NLRP)3 inflammasome to release interleukin (IL)-1β and result in vigorous inflammation. We aimed to characterize crystal-induced NLRP3 activation in placental inflammation and examine its role in pre-eclampsia. We confirmed that serum total cholesterol and uric acid were elevated in pre-eclamptic compared to healthy pregnancies and correlated positively to high sensitivity C-reactive protein (hsCRP) and the pre-eclampsia marker soluble fms-like tyrosine kinase-1 (sFlt-1). The NLRP3 inflammasome pathway components (NLRP3, caspase-1, IL-1β) and priming factors [complement component 5a (C5a) and terminal complement complex (TCC)] were co-expressed by the syncytiotrophoblast layer which covers the placental surface and interacts with maternal blood. The expression of IL-1β and TCC was increased significantly and C5a-positive regions in the syncytiotrophoblast layer appeared more frequent in pre-eclamptic compared to normal pregnancies. In-vitro activation of placental explants and trophoblasts confirmed NLRP3 inflammasome pathway functionality by complement-primed crystal-induced release of IL-1β. This study confirms crystal-induced NLRP3 inflammasome activation located at the syncytiotrophoblast layer as a mechanism of placental inflammation and suggests contribution of enhanced NLRP3 activation to the harmful placental inflammation in pre-eclampsia.

Increased microvascular proliferation is negatively correlated to tumour blood flow and is associated with unfavourable outcome in endometrial carcinomas

Background:

We aimed to study the angiogenic profile based on histomorphological markers in endometrial carcinomas in relation to imaging parameters obtained from preoperative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) and to explore the potential value of these markers to identify patients with poor outcome.

Methods:

In fifty-four surgically staged endometrial carcinoma patients, immunohistochemical staining with factor VIII and Ki67 allowed assessment of microvessel density (MVD) and microvascular proliferation reflecting tumour angiogenesis. In the same patients, preoperative pelvic DCE-MRI and DWI allowed the calculation of parameters describing tumour microvasculature and microstructure in vivo.

Results:

Microvascular proliferation was negatively correlated to tumour blood flow (Fb) (r=−0.36, P=0.008), capillary permeability surface area product (PS) (r=−0.39, P=0.004) and transfer from the blood to extravascular extracellular space (EES) (Ktrans) (r=−0.40, P=0.003), and was positively correlated to tumour volume (r=0.34; P=0.004). High-tumour microvascular proliferation, low Fb and low Ktrans were all significantly associated with reduced progression/recurrence-free survival (P<0.05).

Conclusion:

Disorganised angiogenesis with coexisting microvascular proliferation and low tumour blood flow is a poor prognostic factor supporting that hypoxia is associated with progression and metastatic spread in endometrial carcinomas.

Increased endoplasmic reticulum stress in decidual tissue from pregnancies complicated by fetal growth restriction with and without pre-eclampsia

OBJECTIVES

Endoplasmic reticulum (ER) stress has been implicated in both pre-eclampsia (PE) and fetal growth restriction (FGR), and is characterised by activation of three signalling branches: 1) PERK-pEIF2α, 2) ATF6 and 3) splicing of XBP1(U) into XBP1(S). To evaluate the contribution of ER stress in the pathogenesis of PE relative to FGR, we compared levels of ER stress markers in decidual tissue from pregnancies complicated by PE and/or FGR.

STUDY DESIGN

Whole-genome transcriptional profiling was performed on decidual tissue from women with PE (n = 13), FGR (n = 9), PE+FGR (n = 24) and controls (n = 58), and used for pathway and targeted transcriptional analyses of ER stress markers. The expression and cellular localisation of ER stress markers was assesses by Western blot and immunofluorescence analyses.

RESULTS

Increased ER stress was observed in FGR and PE+FGR, including both the PERK-pEIF2α and ATF6 signalling branches, whereas ER stress was less evident in isolated PE. However, these cases demonstrated elevated levels of XBP1(U) protein. ATF6 and XBP1 immunoreactivity was detected in most (>80%) extravillous trophoblasts, decidual cells and macrophages. No difference in the proportion of immunopositive cells or staining pattern was observed between study groups.

CONCLUSIONS

Increased PERK-pEIF2α and ATF6 signalling have been associated with decreased cellular proliferation and may contribute to the impaired placental growth characterising pregnancies with FGR and PE+FGR. XBP1(U) has been proposed as a negative regulator of ER stress, and increased levels in PE may reflect a protective mechanism against the detrimental effects of ER stress.

STOX2 but not STOX1 is differentially expressed in decidua from pre-eclamptic women: data from the Second Nord-Trondelag Health Study

Variation in the Storkhead box-1 (STOX1) gene has previously been associated with pre-eclampsia. In this study, we assess candidate single nucleotide polymorphisms (SNPs) in STOX1 in an independent population cohort of pre-eclamptic (n = 1.139) and non-pre-eclamptic (n = 2.269) women (the HUNT2 study). We also compare gene expression levels of STOX1 and its paralogue, Storkhead box-2 (STOX2) in decidual tissue from pregnancies complicated by pre-eclampsia and/or fetal growth restriction (FGR) (n = 40) to expression levels in decidual tissue from uncomplicated pregnancies (n = 59). We cannot confirm association of the candidate SNPs to pre-eclampsia (P > 0.05). For STOX1, no differential gene expression was observed in any of the case groups, whereas STOX2 showed significantly lower expression in deciduas from pregnancies complicated by both pre-eclampsia and FGR as compared with controls (P = 0.01). We further report a strong correlation between transcriptional alterations reported previously in choriocarcinoma cells over expressing STOX1A and alterations observed in decidual tissue of pre-eclamptic women with FGR.

Placental expression of glycophosphatidylinositol (GPI)-anchored proteins in paroxysmal nocturnal haemoglobinuria

Paroxysmal nocturnal haemoglobinuria (PNH) is a clonal stem cell disorder in which a defect of glycophosphatidylinositol (GPI)-anchored proteins leads to higher morbidity and mortality because of intravascular haemolysis, haemoglobinuria, pancytopenia and an increased frequency of thrombotic events. We report here the clinical features of a pregnant woman with PNH and present an immunhistochemical analysis of complement regulators, leukocyte activation markers and placental alkaline phosphatase (PALP) on syncytiotrophoblasts and inflammatory cells in her placenta. Placental tissue from normal deliveries served as controls. The patient had severe PNH with haemolysis, thrombosis episodes and signs of bone marrow failure. Placental syncytiotrophoblasts and villous cells of fetal origin in both normal placentas and the placenta from the PNH patient expressed PALP and the complement regulators CD46, CD55 and CD59. Additionally, CD11b-positive leukocytes of presumed maternal origin were negative for CD15 in the PNH placenta, while they stained positive within the villous space and in normal placentas. These findings show that fetally derived cells in the PNH placenta expressed GPI-linked molecules that are known to be of importance for a successful pregnancy outcome.

Minimal residual disease in ovarian cancer as a target for complement-mediated mAb immunotherapy

Ovarian cancer is potentially well suited for local monoclonal antibody (mAb) immunotherapy, because it remains within the peritoneal cavity for a long period of time before giving rise to distant metastases. At the stage of minimal residual disease, the cells appear to be in a state of dormancy (G(0)) or at least have lower rates of tumour cell proliferation. They should be a promising target for immunotherapy. Here we first examined the cell-cycle expression of CD59 and decay-accelerating factor (DAF; CD55) on four different ovarian carcinoma cell lines, using simultaneous flow cytometric analysis of DNA content or the cell-cycle-specific nuclear proliferation protein Ki67 and CD59 or DAF surface expression. We found that CD59 and DAF are stably expressed throughout the cell cycle. The polyvalent approach to target-independent antigens to improve the efficiency of mAb complement (C)-mediated damages was promising, and tumour cells become sensitive to C damage, when incubated with cross-linked mAb against different tumour-associated antigens. Although, such immune complex-mediated C activation was rather ineffective in killing the cells, it could be potentiated by the addition of blocking mAb against CD59 and DAF. Our results suggest that the activities of intrinsic C regulators must be neutralized to make minimal residual disease a promising target for antibody therapy.

Ascitic complement system in ovarian cancer

Ovarian cancer spreads intraperitoneally and forms fluid, whereby the diagnosis and therapy often become delayed. As the complement (C) system may provide a cytotoxic effector arm for both immunological surveillance and mAb-therapy, we have characterised the C system in the intraperitoneal ascitic fluid (AF) from ovarian cancer patients. Most of the AF samples showed alternative and classical pathway haemolytic activity. The levels of C3 and C4 were similar to or in the lower normal range when compared to values in normal sera, respectively. However, elevated levels of C3a and soluble C5b-9 suggested C activation in vivo. Malignant cells isolated from the AF samples had surface deposits of C1q and C3 activation products, but not of C5b-9 (the membrane attack complex; MAC). Activation could have become initiated by anti-tumour cell antibodies that were detected in the AFs and/or by changes on tumour cell surfaces. The lack of MAC was probably due to the expression of C membrane regulators CD46, CD55 and CD59 on the tumour cells. Soluble forms of C1 inhibitor, CD59 and CD46, and the alternative pathway inhibitors factor H and FHL-1 were present in the AF at concentrations higher than in serum samples. Despite the presence of soluble C inhibitors it was possible to use AF as a C source in antibody-initiated killing of ovarian carcinoma cells. These results demonstrate that although the ovarian ascitic C system fails as an effective immunological surveillance mechanism, it could be utilised as an effector mechanism in therapy with intraperitoneally administrated mAbs, especially if the intrinsic C regulators are neutralised.

Secretion of soluble complement inhibitors factor H and factor H-like protein (FHL-1) by ovarian tumour cells

We observed that the soluble complement regulators factor H and factor H-like protein were abundantly present in ascites samples as well as in primary tumours of patients with ovarian cancer. RT-PCR and immunoblotting analyses showed that the two complement inhibitors were constitutively produced by the ovarian tumour cell lines SK-OV-3 and Caov-3, but not PA-1 or SW626 cells. The amounts of factor H-like protein secreted were equal to those of factor H. This is exceptional, because e.g. in normal human serum the concentration of factor H-like protein is below 1/10th of that of factor H. In ascites samples the mean level of factor H-like protein (130+/-55 microg ml(-1)) was 5.5-fold higher than in normal human serum (24+/-3 microg ml(-1)). Ovarian tumour cells thus preferentially synthesise factor H-like protein, the alternatively spliced short variant of factor H. The tumour cells were found to bind both (125)I-labelled factor H and recombinant factor H-like protein to their surfaces. Surprisingly, the culture supernatants of all of the ovarian tumour cell lines studied, including those of PA-1 and SW626 that did not produce factor H/factor H-like protein, promoted factor I-mediated cleavage of C3b to inactive iC3b. Subsequently, the PA-1 and SW626 cell lines were found to secrete a soluble form of the membrane cofactor protein (CD46). Thus, our studies reveal two novel complement resistance mechanisms of ovarian tumour cells: (i) production of factor H-like protein and factor H and (ii) secretion of soluble membrane cofactor protein. Secretion of soluble complement inhibitors could protect ovarian tumour cells against humoral immune attack and pose an obstacle for therapy with monoclonal antibodies.

[Mifepristone--a controversial drug with great potential]

BACKGROUND

Antiprogestins, agents that inhibit the action of progesterone, are among the most controversial and yet the more interesting therapeutic compounds developed over the past 20 years.

MATERIAL AND METHODS

We present a review of the literature identified through limited searches on Medline, Cochrane and the Internet, with a discussion of the biological, clinical, political and ethical aspects of this important drug.

RESULTS

The first effective antiprogestin in clinical use was mifepristone (also known as RU 486). This agent provides the most effective and safest means of medical abortion. It may also be used as a contraceptive and delivery-inducing agent and in the treatment of spontaneous abortion, ectopic pregnancies, leiomyoma, endometriosis, intrauterine fetal death, Cushing's syndrome and progesterone-dependent malignancies.

INTERPRETATION

The introduction of mifepristone as an abortion-inducing agent has created intense political, ethical and moral controversies which have delayed clinical investigations and evaluations for potential expanded use.

Early pregnancy termination with mifepristone and misoprostol in Norway

OBJECTIVES

Medical abortion was first introduced in Norway in April 1998. The aims of this study were to assess the efficacy, side effects, and acceptability of medical abortion using mifepristone orally and misoprostol vaginally in a Norwegian population.

DESIGN

The study included the first 226 pregnant women with gestational age of <63 days who requested nonsurgical abortion during the first year in the first Norwegian hospital using this regimen.

METHODS

All women received a single dose of mifepristone 600 mg orally, followed at 48 hours by 800 microg misoprostol vaginally. Treatment outcome and complications were the principal outcome measures. We also measured the rates of side effects such as abdominal pain and bleeding and the women's acceptability of treatment.

RESULTS

Abortion was successful in 95%, surgical evacuation became necessary in 4%, and the pregnancy continued in one woman. During the study period the method was chosen by 23% of those requesting abortion before 63 days amenorrhea; 80% would use the method again; 81% would recommend it to a friend; in retrospect, 69% would not have been willing to be randomly allocated to either a medical or a surgical method.

CONCLUSIONS

The combination of orally administrated mifepristone and vaginally administrated misoprostol is an abortion method that is both effective and safe, has few side effects and is well accepted by Norwegian women.

[Pathophysiology and clinical manifestations in pre-eclampsia]

BACKGROUND

Preeclampsia is a progressive, multisystem disorder characterised by hypertension and proteinuria. A body of evidence suggest a genetic basis; it is generally accepted that the underlying pathological processes are in the placenta.

MATERIAL AND METHODS

This article is a review of the pathophysiology of preeclampsia based on literature mainly obtained through PubMed and Medline searches.

RESULTS

A poorly perfused placenta, secondary to defective placental invasion of the spiral arteries, may lead to hypoxia and insufficient perfusion and cause release of cytokines which damage endothelial cells and cause dysfunction. Women with preeclampsia have markedly elevated concentrations of triglyceride-rich lipoproteins. Lipid peroxidation also causes endothelial dysfunction and thus contributes to preeclampsia. Placenta is one source of the lipid peroxides. Antioxidant deficiency is also a predisposing factor. Hyperhomocysteinaemia, protein S and protein C deficiency, and activated protein C resistance appear to be involved in the pathophysiology of severe preeclampsia and early onset preeclampsia.

INTERPRETATION

The new information about mechanisms for development of preeclampsia gives a basis for new treatment modalities.

[HELLP syndrome]

BACKGROUND

The HELLP syndrome (H = hemolysis, EL = elevated liver enzymes, LP = low platelets) is a pregnancy complication which affects 10-20% of cases of severe preeclampsia.

MATERIAL AND METHODS

The article is a review of the literature.

RESULTS

Approximately 70% of HELLP syndrome cases occur before delivery, 15% as early as in the second trimester, the remainder after delivery. The classical HELLP syndrome is characterised by abdominal pain, pathological liver tests and low platelets. However, some cases are atypical; hypertension and abdominal pain may both be absent. Genetic as well as immunologic factors are involved in the pathogenesis. There is an imbalance in the coagulation process in the placenta. Activated leukocytes and macrophages induce production of cytokines that may reach the general circulation and cause endothelial dysfunction. In the HELLP syndrome fibrin deposits are also found in the vessels and in the liver sinusoides.

INTERPRETATION

A mother with a classic HELLP syndrome should be delivered after stabilisation of the clinical condition. A partial HELLP syndrome can be observed. Treatment with corticosteroids is beneficial.

[Pre-eclampsia--a review]

BACKGROUND

Preeclampsia is characterized by hypertension and proteinuria with or without oedema.

MATERIAL AND METHODS

The authors highlight some aspects of preeclampsia: epidemiology, classification, clinical evaluation and treatment.

RESULTS

The condition may be classified as light or severe. Preeclampsia can induce damage to the placenta, liver, kidneys and brain, in addition to complications like the HELLP syndrome, placental abruption and eclampsia. Thrombocyte activation may cause activation of the coagulation system and thrombocytopenia. Early onset preeclampsia (< 34 weeks) is often associated with placental infarcts and reduced fetal growth.

INTERPRETATION

We focus on early signs and close clinical surveillance. The diastolic blood pressure should be estimated with Korotkoffs' phase V. Patients with early onset preeclampsia should be hospitalized, as should women with hypertension and newly developed proteinuria. Antihypertensive treatment is discussed. Cases with reduced fetal growth and those with severe preeclampsia should in most cases be delivered preterm. Vaginal delivery is preferable. Labour may be induced by oxtocin, following cervical prostaglandin stimulation as indicated. In such cases cardiotocography surveillance during labour should be performed. Caesarean section may be performed in selected cases. Patients with mild preeclampsia can await spontaneous vaginal delivery at term, but delivery should be induced if they proceed past term.

Decreased expression of protectin (CD59) in gut epithelium in ulcerative colitis and Crohn's disease

Without adequate protection, the cells of the human body would be susceptible to destruction by the complement system. The main defense against complement lysis is a molecule called protectin (CD59) that is widely distributed in human tissues. Because the complement system has been suggested to be involved in the pathogenesis of inflammatory bowel diseases, we examined the expression of protectin in the colonic epithelium of patients with ulcerative colitis or Crohn's disease and controls. Colorectal specimens from 6 patients with ulcerative colitis, 8 patients with Crohn's disease, and 4 controls were obtained from surgical resections. Frozen sections of the specimens were immunostained for protectin using the Bric 229 monoclonal antibody. The expression of protectin was found to be decreased in the epithelium of patients with ulcerative colitis. In patients with Crohn's disease, the epithelial expression of protectin was decreased in diseased areas of gut while the expression did not significantly differ from that in controls in macroscopically normal areas. There was no difference in the expression of protectin on vascular endothelium, mononuclear cells, or smooth muscle. The reduction in epithelial expression of protectin in patients with ulcerative colitis or Crohn's disease may render epithelial cells vulnerable to complement lysis and lead to the destruction of gut epithelium as seen typically in these diseases.

[The complement system--structure, activation, regulation and function]

Activation of the complement system plays a key role in normal inflammatory response to injury but may cause substantial injury when activated inappropriately. The cascade is activated through classical, alternative and lectin pathways. The human complement system is in most cases well controlled by the host, and inappropriate activation and host cell destruction are prevented. The control is mainly mediated by complement regulatory proteins. The use of powerful methodologies in molecular biology, biochemistry and physiology has led to impressive advances in our knowledge of the mechanisms of complement activation and regulation and its role as either a protective or pathogenic factor in human disease. With respect to disease pathogenesis, the complexity of the cascades provides opportunities for several different therapeutic targets within the pathways, and we are about to witness the availability of a variety of complement modulators for specific therapies. This article reviews biological aspects of this important immunological effector mechanism.

Complement-regulatory proteins in ovarian malignancies

Ovarian cancer has features that makes it well-suited for MAb adjuvant immunotherapy. Several of the MAbs used in clinical trials mediate cancer cell destruction by activation of complement (C). In this study, therefore, we examined the ability of ovarian-tumor cells to resist C attack. We found that the C regulators membrane cofactor protein (MCP, CD46) and protectin (CD59) were strongly expressed in the tumor cells in all 28 benign and malignant tumors examined. Decay-accelerating factor (DAF; CD55) was more heterogeneously expressed, and only 75% of the tumors exhibited a moderate amount of DAF in the tumor cells. In adenoma cells, CD59 and DAF were preferentially located apically, while in adenocarcinoma cells they were expressed also at the basolateral cell surface. The ovarian-carcinoma cell lines SK-OV-3, Caov-3, SW626 and PA-1 expressed both the 58- and the 68-kDa isoforms of MCP. DAF was present as a glycosyl-phosphatidylinositol(GPI)-anchored 70-kDa glycoprotein. The surface-expression level of DAF varied, and correlated with the vulnerability of the cells to C-mediated lysis. CD59 was expressed as a GPI-linked 19- to 25-kDa protein exhibiting multiple glycosylation variants. The surface expression of CD59 correlated with the amount of the main 1.9 + 2.1-kb CD59 mRNA transcripts. Neutralization of CD59 with an anti-CD59 MAb significantly enhanced C-mediated killing of the cell lines. Low expression of C regulators on the PA-1 teratocarcinoma cell line was associated with high sensitivity to C lysis. Thus, the expression of C regulators on malignant ovarian cells may constitute a tumor escape mechanism, and is a critical parameter to be examined when MAb therapy is being considered.

Resistance of ovarian teratocarcinoma cell spheroids to complement-mediated lysis

We have shown previously that it is possible to target complement-mediated killing against cultured ovarian tumour cells in vitro. As malignant ovarian cells usually grow in solid nodules in vivo, we have in the present study examined the effectiveness of complement killing against ovarian teratocarcinoma cells (PA-1) growing in three-dimensional tumour microspheroids (TMSs). Our study shows that PA-1 cells growing in TMSs are less susceptible to complement-mediated killing than cells growing in monolayer cultures, even after neutralization of protectin (CD59), the main inhibitor of complement lysis. Cells in suspension and cells growing in TMSs showed a similar expression of membrane co-factor protein (MCP, CD46) and CD59. Decay-accelerating factor (DAF, CD55) was not detected on the surface of cells in suspension, but appeared focally on the outermost cell layers of the TMSs. Complement-activating antibodies bound to all PA-1 cells in suspension but only to the most peripherally located cells in TMSs, even though the target antigens were similarly expressed in the two systems. Antibody-induced complement activation on PA-1 cells in suspension led to C3 and C5b-9 deposition on most cells, while C3 and C5b-9 were only found on the outermost layers of the TMSs. The increased complement resistance of tumour cells growing in three-dimensional spheroids is partly because of an insufficient penetration of antibodies and complement into the TMSs. TMSs are a useful model for the development of more efficient ways to kill malignant cells in micrometastases with monoclonal antibodies and complement.

Characterisation of the complement-regulatory proteins decay-accelerating factor (DAF, CD55) and membrane cofactor protein (MCP, CD46) on a human colonic adenocarcinoma cell line

To avoid destruction by complement, normal and malignant cells express membrane glycoproteins that restrict complement activity. These include decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46) and protectin (CD59), which are all expressed on colonic adenocarcinoma cells in situ. In this study we have characterised the C3/C5 convertase regulators DAF and MCP on the human colonic adenocarcinoma cell line HT29. DAF was found to be a glycosyl-phosphatidylinositol-anchored 70-kDa glycoprotein. Blocking experiments with F(ab')2 fragments of the anti-DAF monoclonal antibody BRIC 216 showed that DAF modulates the degree of C3 deposition and mediates resistance to complement-mediated killing of the cells. The expression and function of DAF were enhanced by tumour necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1 beta). Cells incubated with interferon gamma (IFN gamma) did not alter their DAF expression. Two MCP forms were expressed, with molecular masses of approximately 58 kDa and 68 kDa, the lower form predominating. MCP expression was up-regulated by IL-1 beta, but not by TNF alpha or INF gamma. Expression of DAF and MCP promotes resistance of colonic adenocarcinoma cells to complement-mediated damage, and represents a possible mechanism of tumour escape.

Identification of the complement regulatory protein CD59 in human colostrum and milk

PROBLEM

Complement lytic activity has been demonstrated, and a potential for its activation is present in human colostrum and milk. This necessitates the presence of regulatory mechanisms protecting epithelial cells in the oropharynx and the gastrointestinal tract of the infant, the milk cellular elements, and bacteria colonizing the oropharynx and the gastrointestinal tract. Lactoferrin and C1 inhibitor have been attributed such a role. However, it is likely that additional protection against the cytolytic activity of the membrane attack complex is required. This has lead us to investigate the presence of the complement regulatory protein CD59 in human colostrum and milk, and to further characterize the source of secretion.

METHOD

Samples of human colostrum and milk were obtained from volunteers at different stages of lactation, and separated into fat, skim milk, and milk cellular elements by centrifugation. Normal human mammary gland tissues were obtained from patients undergoing biopsy for benign conditions. SDS-PAGE and Western blotting, and an immuno dot-blot assay were used to identify CD59 in human milk. Immunohistochemistry was performed on all tissue samples and cytospins of the milk cellular elements, using monoclonal antibodies to CD59.

RESULTS

CD59 was present in cell-free colostrum and milk as a 19-25 kDa glycoprotein. No variation in CD59 levels was detected between colostrum and milk. CD59 was present in great amounts in the cytoplasm and was highly expressed on the surface membrane on mammary gland acinar and ductal epithelial cells, while the milk cellular elements contained CD59 mainly in their cytoplasm.

CONCLUSION

The complement regulatory protein CD59 present in cell-free human colostrum and milk may exert its effects both in the mammary gland and in the oropharynx and gastrointestinal tract of the infant. The lobuloalveolar epithelial cells in the mammary gland are the likely source of secretion.

Down-regulation of CD59 (protectin) expression on human colorectal adenocarcinoma cell lines by levamisole

The vulnerability of tumour cells to complement-mediated immune attack is regulated by membrane associated molecules. Recently, we have shown that the expression of the membrane attack complex inhibitor CD59 is enhanced on colonic adenocarcinoma cells compared to normal colonic epithelial cells. CD59 was shown, in the same study, to protect the tumour cells from complement-mediated lysis. Levamisole (LMS), used in conjunction with 5-fluorouracil as adjuvant therapy, reduces the incidence of colon cancer relapse following surgical resection. This led to our investigation of the effect of LMS on CD59 expression and function on the human colorectal cell lines HT29 and Caco-2. When cultured in the presence of 10 microM LMS, the cells reduced their expression of CD59 in a time-dependent manner. LMS treated HT29 cells were more sensitive to lysis by complement than control cells, and the reduction in CD59 expression was shown to be partly responsible for this. A reduction in CD59 expression will augment complement-mediated immune surveillance and may contribute to LMSs anti-tumour activity in vivo.

Identification of the complement regulatory proteins CD46, CD55, and CD59 in human fallopian tube, endometrium, and cervical mucosa and secretion

PROBLEM

Complement lytic activity has been demonstrated, and a potential for its activation is present in human cervical and tubal secretions and in the endometrium. This necessitates the presence of regulatory mechanisms for protection of the sperm and the implanting allogeneic conceptus in the female genital tract. Complement regulatory proteins demonstrated on sperm and in seminal fluid have been attributed such a role. It is however likely that additional protection is required for a successful conception and implantation to take place. This lead us to investigate the distribution of the complement regulatory factors in cervical mucus and mucosa, uterine endometrium, and fallopian tube.

METHOD

Endometrium and cervical mucosa were obtained from patients undergoing hysterectomy for benign conditions, and specimens were selected from different stages of the menstrual cycle. Fallopian tubes were obtained from patients submitted for sterilization, while cervical mucus was aspirated from volunteers undergoing gynecological examination. Immunohistochemistry was performed on all tissue samples, using monoclonal antibodies to membrane cofactor protein (MCP), decay accelerating factor (DAF), CD59 and complement receptor 1 (CR1). Western blot analysis was performed on cervical mucus under nonreducing conditions.

RESULTS

MCP, DAF, and CD59 were found to be expressed in human endometrium and fallopian tube. No variation in expression was detected throughout the menstrual cycle. CR1 was not expressed. Soluble forms of DAF and CD59 were found to be present in cervical mucus.

CONCLUSION

The complement regulatory proteins MCP, DAF, and CD59 are expressed throughout the female genital tract, and may thus play an important role in protecting the traversing sperm and implanting blastocyst from complement mediated damage.

The influence of tumour necrosis factor-alpha, interleukin-1 beta and interferon-gamma on the expression and function of the complement regulatory protein CD59 on the human colonic adenocarcinoma cell line HT29

CD59 is a 18-25 kDa glycoprotein which, by inhibiting the formation of the membrane attack complex, protects homologous cells from complement mediated damage. We have described recently the expression and complement regulatory function of CD59 on colonic adenocarcinoma cells both in vivo and in vitro. In this study we have examined the influence of cytokines on the expression and complement regulatory function of CD59 on the colonic adenocarcinoma cell line HT29. CD59 expression on the HT29 cells was up-regulated after stimulation by mononuclear cells activated by mixed lymphocyte reaction and by culture supernatants from activated mononuclear cells. Similarly, a dose-dependent increase in CD59 expression was observed after stimulation with both tumour necrosis factor-alpha and interleukin-1 beta. A dose-dependent increase in the level of CD59 expression was also seen using low concentrations of interferon-gamma (IFN-gamma), while CD59 expression on cells cultured with high IFN-gamma concentrations was comparable to non-stimulated cells. Cytokine treated cells were more resistant to lysis by homologous complement than non-stimulated cells, and the increase in CD59 expression was shown to be partially responsible for this. The present data strengthen the role of CD59 as a possible participant in tumour escape.

The expression of CD59 in normal human nervous tissue

The expression of CD59, a complement regulator of the formation and function of the terminal cytolytic membrane attack complex, was studied in human normal nervous tissue by immunohistochemical markers using two monoclonal antibodies 1F5 and MEM43. CD59 was present on Schwann cells, neurons and endothelial cells in the peripheral nervous system (PNS), and on Schwann cells in culture. In the central nervous system (CNS) CD59 was found predominantly on endothelial cells. There was also a diffuse staining of white and grey matter of the spinal cord and brain, presumably of microglia, oligodendrocytes, astrocytes and neurons, as these cells were CD59 positive in culture. Furthermore, CD59 was detected in the cerebrospinal fluid (CSF) of healthy individuals. CD59 in the PNS and CNS was glycosyl-phosphatidylinositol linked and had a molecular weight of 19,000-25,000. The presence of CD59 on various cells of the nervous system and in the CSF suggests that regulation of complement activation by this protein is important in neural host defence mechanisms.

Fc gamma-receptor activity of placental annexin II

We have previously produced a MoAb, B1D6, against a placental FcR. The antigen isolated using F(ab')2-fragments of B1D6 exhibits Fc-binding properties with low affinity for IgG. The antigen is a single-chained glycoprotein with a molecular weight of approximately 37 kDa and a pI of about 7.0-8.5. Amino acid sequences from enzymatic digests of the antigen indicated that it is annexin II. Immunoreactivity using anti-annexin antisera and purified placental annexin II have further established the specificity of B1D6 to annexin II. The B1D6 epitope appears to be intramembraneous and intracellular on placental syncytiotrophoblasts, monocytes and other cells investigated.

Expression and function of CD59 on colonic adenocarcinoma cells

The expression and function of CD59, a 19-25 kDa membrane glycoprotein that inhibits formation of the membrane attack complex of complement, was analyzed on normal and malignant human colonic epithelial cells. Analysis by immunofluorescence demonstrated a weak apical expression of CD59 on normal intestinal epithelium, with an increased expression on adenocarcinoma cells. The expression of CD59 was greatest on tumor cells with poor differentiation. The functional activity of CD59 on human adenocarcinoma cells was investigated using the colonic adenocarcinoma cell line HT29. CD59 on HT29 cells was glycosyl-phosphatidylinositol-linked, and had a molecular mass of 19-25 kDa. HT29 cells expressed approximately four times more CD59 than leukocytes, and showed a high resistance to antibody-dependent complement-mediated lysis. Blocking of CD59 with divalent antigen-binding F(ab')2 fragments of the anti-CD59 monoclonal antibody 1F5 resulted in a dose-dependent increase in complement-mediated lysis, suggesting that CD59 may be of importance in protecting colonic adenocarcinoma cells against complement-mediated cytolysis.