Peritoneal Mesothelium Research Articles

Transforming growth factor beta 1(TGFβ1) and progesterone differentially regulate matrix metalloproteinases (MMPs) in human normal endometrium and endometriosis

IL-1β, TNF-α and TGFβ1 are increased in peritoneal fluid samples from women with endometriosis. Invasion of ectopic endometrium into peritoneal mesothelium requires matrix metalloproteinases (MMPs) for tissue remodeling. Menstruation is preceded by progesterone withdrawal, collagen degradation and matrix remodeling predominantly through induction MMPs and recruitment of invading neutrophils. Thus, elucidation of the mechanism underlying regulation of MMP gene expression in the endometrium will be helpful for understanding normal menstruation but also treatment of endometriosis.

Splenic localization of the peritoneal mesothelioma: case report and literature revue

Peritoneal mesothelioma is a rare form of malignant mesothelioma, making up <30% of diagnosed mesothelioma cases. Because of a lack of specific symptoms (abdominal pain, abdominal swelling), normally it is diagnosed in advanced stages, sometimes in a surgical emergency (intestinal obstruction, severe ascites) and occasionally during image procedures or laparoscopy which can show a mass developing from peritoneal mesothelium surfaces, or an accumulation of small irregularities that may be tumors or plaques. The reported case refers to a particular localization of a peritoneal mesothelioma, the spleen, discovered only after a splenectomy, due to the clinical and radiological suspect of a rupture.

Abstract 1527: Hepatocyte growth factor modulates adhesion of ovarian cancer cells to the peritoneum mesothelium through p70 S6 kinase

Abstract Ovarian cancer has the highest mortality of all gynecological cancers. These deaths are mainly due to the highly metastatic characteristic with already widespread peritoneal dissemination and malignant ascites at the time of diagnosis. However the molecular mechanisms that regulate ovarian cancer progression are poorly understood. A key step in this process is the adhesion of ovarian cancer cells to the peritoneal mesothelium. Hepatocyte growth factor (HGF) is present at high concentrations in ovarian cancer ascitic fluid. We show here a role for HGF signaling in the regulation of the peritoneal adhesion of ovarian cancer cells. HGF increased binding of ovarian cancer cells to peritoneal extracellular matrix (ECM) proteins fibronectin and laminin and their receptors α5, α6, and β1 integrin expression. Blockade of HGF resulted in reduced attachment of ovarian cancer cells to these ECM proteins, with a concomitant reduction of α5, α6, and β1 integrin expression, confirming that the effect was HGF specific. Similarly, the peritoneal ECM adhesion could be reversed by neutralizing antibodies to α5, α6, and β1 integrin. The adhesive phenotype and integrin expression activated by HGF could be blocked by specific inhibition of p70 S6 kinase (p70S6K) using short hairpin RNA or small molecule inhibitor, suggesting that HGF transmits the signal through p70S6K. Importantly, it also inhibited adhesion to primary human peritoneal mesothelial cells. These results identify a potential novel mechanism for HGF-induced peritoneal adhesion, which is mediated through p70S6K through regulation of α5, α6, and β1 integrin (This work is supported by the Hong Kong Research Grants Council Grant HKU7599/05M to A.S.T.W.). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1527. doi:10.1158/1538-7445.AM2011-1527

The Fallopian Tube-Peritoneal Junction

Junctions between different types of epithelia are hot spots for carcinogenesis, but the junction of the peritoneal mesothelium with the fallopian tubal epithelium, the tubal-peritoneal junction, has not been characterized earlier. A total of 613 junctional foci in 228 fallopian tube specimens from 182 patients who underwent surgery for a variety of indications, including 27 risk-reducing salpingo-oophorectomy specimens, were studied. Edema, congestion, and dilated lymphatic channels were commonly present. Transitional metaplasia was found at the junction in 20% of patients and mesothelial hyperplasia in 17%. Inflammation at the junction was seen predominantly in patients with salpingitis, torsion, or tubal pregnancy. Ovarian-type stroma was found at the junction in 5% of patients, and was found elsewhere in the tubal lamina propria in an additional 27% of patients. Findings in risk-reducing salpingo-oophorectomy specimens in women with BRCA mutations, a personal history of breast cancer, and/or a family history of breast/ovarian cancer were similar to those in controls. Transitional metaplasia specifically localizes to this junction, and is the probable source of Walthard cell nests. The recently highlighted significance of fimbrial tubal epithelium in the origin of serous ovarian carcinomas and a study suggesting that mucinous and Brenner tumors may arise from transitional-type epithelium in this location suggest that the tubal-peritoneal junction may play a role in the development of these tumors. This is the first comprehensive description of a hitherto unrecognized transitional zone in the adnexa.

Peritoneal repairing cells: a type of bone marrow derived progenitor cells involved in mesothelial regeneration

The peritoneal mesothelium exhibits a high regenerative ability. Peritoneal regeneration is concomitant with the appearance, in the coelomic cavity, of a free-floating population of cells whose origin and functions are still under discussion. We have isolated and characterized this cell population and we have studied the process of mesothelial regeneration through flow cytometry and confocal microscopy in a murine model lethally irradiated and reconstituted with GFP-expressing bone marrow cells. In unoperated control mice, most free cells positive for mesothelin, a mesothelial marker, are green fluorescent protein (GFP). However, 24 hrs after peritoneal damage, free mesothelin+/ GFP+ cells appear in peritoneal lavages. Cultured lavage peritoneal cells show colocalization of GFP with mesothelial (mesothelin, cytokeratin) and fibroblastic markers. Immunohistochemical staining of the peritoneal wall also revealed colocalization of GFP with mesothelial markers and with procollagen-1 and smooth muscle α-actin. This was observed in the injured area as well as in the surrounding not-injured peritoneal surfaces. These cells, which we herein call peritoneal repairing cells (PRC), are very abundant 1 week after surgery covering both the damaged peritoneal wall and the surrounding uninjured area. However, they become very scarce 1 month later, when the mesothelium has completely healed. We suggest that PRC constitute a type of monocyte-derived cells, closely related with the tissue-repairing cells known as ‘fibrocytes’ and specifically involved in peritoneal reparation. Thus, our results constitute a synthesis of the different scenarios hitherto proposed about peritoneal regeneration, particularly recruitment of circulating progenitor cells and adhesion of free-floating coelomic cells.

Abstract 5190: GnRH promotes peritoneal adhesion and dissemination of ovarian cancer cells

Abstract Ovarian cancer has the highest mortality of all gynecological cancers. It is often diagnosed at a late stage characterized by widespread peritoneal dissemination and malignant ascites. A key initial step in metastasis is the adhesion of ovarian cancer cells to the peritoneal mesothelium and extracellular matrix (ECM). Gonadotropin-releasing hormone (GnRH) receptor is present in 80% of ovarian carcinomas and its role in ovarian cancer cell migration/invasion has recently been revealed. Here, we show for the first time a role for GnRH in promoting ovarian cancer cell adhesion to the peritoneum. We observed that GnRH agonist (GnRHa)-stimulated cells were able to adhere to the peritoneal mesothelium efficiently. Moreover, the expression of integrins (α2, α5 and β1) in ECM recognition for collagen I, laminin, and fibronectin were upregulated and activated by GnRHa. The adhesion of ovarian cancer cells to the mesothelium/ECM components activated by GnRHa could be blocked by neutralizing antibodies to α2, α5 and β1 integrin. Knockdown of the GnRH receptor using small interfering RNA significantly abrogated the GnRH-induced cell adhesion and integrin expression, confirming that these effects were GnRH receptor specific. Furthermore, we showed that downregulation of β1 integrin and GnRH receptor with short hairpin RNA-mediated gene silencing significantly reduced ascites formation and intra-abdominal metastasis in intraperitoneal xenografts of human ovarian cancer in nude mice. These results indicate that GnRH may play a critical role in the peritoneal adhesion and dissemination of ovarian carcinomas and could be a promising target in ovarian cancer (This work is supported by the Hong Kong Research Grants Council Grant HKU778108 to A.S.T.W.). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5190.

Hereditary renal adysplasia, pulmonary hypoplasia and Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome: a case report

BackgroundHereditary renal adysplasia is an autosomal dominant trait with incomplete penetrance and variable expression that is usually associated with malformative combinations (including Müllerian anomalies) affecting different mesodermal organs such as the heart, lung, and urogenital system.Case reportA case showing pulmonary hypoplasia, hip dysplasia, hereditary renal adysplasia, and Mayer-Rokitansky-Kuster-Hauser syndrome in adulthood is reported here. The i.v. pyelography showed right renal agenesis with a normal left kidney and ureter. Ultrasound and Magnetic Resonance Imaging also showed right renal agenesis with multicystic embryonary remnants in the right hemipelvis probably corresponding to a dysgenetic kidney. An uretrocystoscopy showed absence of ectopic ureter and of the right hemitrigone. She was scheduled for a diagnostic laparoscopy and creation of a neovagina according to the McIndoe technique with a prosthesis and skin graft. Laparoscopy confirmed the absence of the uterus. On both sides, an elongated, solid, rudimentary uterine horn could be observed. Both ovaries were also elongated, located high in both abdominal flanks and somewhat dysgenetics. A conventional cytogenetic study revealed a normal female karyotype 46, XX at a level of 550 GTG bands. A CGH analysis was performed using a 244K oligoarray CGH detecting 11 copy number variants described as normal variants in the databases. The 17q12 and 22q11.21 microdeletions described in other MRKH patients were not present in this case. Four years after operation her evolution is normal, without symptoms and the neovagina is adequately functional. The geneticists have studied her family history and the pedigree of the family is shown.ConclusionsWe suggest that primary damage to the mesoderm (paraaxil, intermediate, and lateral) caused by mutations in a yet unidentified gene is responsible for: 1) skeletal dysplasia, 2) inappropriate interactions between the bronchial mesoderm and endodermal lung bud as well as between the blastema metanephric and ureteric bud, and eventually 3) Müllerian anomalies (peritoneal mesothelium) at the same level. These anomalies would be transmitted as an autosomal dominant trait with incomplete penetrance and variable expressivity.

Oxidative stress‐dependent increase in ICAM‐1 expression promotes adhesion of colorectal and pancreatic cancers to the senescent peritoneal mesothelium

Intercellular adhesion molecule-1 (ICAM-1) has been implicated in adhesion of colorectal and pancreatic cancer cells (of the SW480 and PSN-1 line, respectively) to the peritoneal mesothelium. It has been demonstrated that ICAM-1 expression increases with senescence in some cell types, however, the significance of this phenomenon in the context of malignant dissemination remains elusive. In this report we show that the adherence of SW480 and PSN-1 cells to senescent human omentum-derived mesothelial cells (HOMCs) in vitro is greater than to early-passage cells and that the effect is mediated by ICAM-1. Senescent HOMCs display increased expression of ICAM-1 mRNA and cell surface protein. The development of this phenotype is related to increased oxidative stress in senescent cells. The augmented ICAM-1 expression in HOMCs can be reduced by culturing cells with antioxidants; in contrast, exposure of HOMCs to an oxidant, t-BHP, leads to cellular senescence and increased ICAM-1 expression. The effect is partly mediated by activation of p38 MAPK and AP-1 signaling pathways. Finally, culture of HOMCs in the presence of a strong antioxidant, PBN, significantly reduces the senescence-associated increase in SW480 and PSN-1 cancer cell binding. These results indicate that increased oxidative stress and increased expression of ICAM-1 in senescent HOMCs may facilitate peritoneal adhesion of selected colorectal and pancreatic cancers.

The Interstitial Lymphatic Peritoneal Mesothelium Axis in Portal Hypertensive Ascites: When in Danger, Go Back to the Sea

Portal hypertension induces a splanchnic and systemic low-grade inflammatory response that could induce the expression of three phenotypes, named ischemia-reperfusion, leukocytic, and angiogenic phenotypes.During the splanchnic expression of these phenotypes, interstitial edema, increased lymph flow, and lymphangiogenesis are produced in the gastrointestinal tract. Associated liver disease increases intestinal bacterial translocation, splanchnic lymph flow, and induces ascites and hepatorenal syndrome. Extrahepatic cholestasis in the rat allows to study the worsening of the portal hypertensive syndrome when associated with chronic liver disease. The splanchnic interstitium, the mesenteric lymphatics, and the peritoneal mesothelium seem to create an inflammatory pathway that could have a key pathophysiological relevance in the production of the portal hypertension syndrome complications. The hypothetical comparison between the ascitic and the amniotic fluids allows for translational investigation. From a phylogenetic point of view, the ancestral mechanisms for amniotic fluid production were essential for animal survival out of the aquatic environment. However, their hypothetical appearance in the cirrhotic patient is considered pathological since ultimately they lead to ascites development. But, the adult human being would take advantage of the potential beneficial effects of this “amniotic-like fluid” to manage the interstitial fluids without adverse effects when chronic liver disease aggravates.

Paratesticular Mesothelioma. Report of a Case With Comprehensive Review of Literature

Paratesticular mesotheliomas are rare tumors with 223 cases described so far. The sole plausible causative factor so far ascertained in the pathogenesis of these tumors is asbestos, which however is found in only around 30% to 40% of such cases. The age range of affected individuals is wide, mostly adults and the elderly, but also includes young people and children. The most common presenting symptom is either hydrocele of unknown origin or intrascrotal mass. When hydrocele is the presenting symptom, these tumors are often clinically overlooked and the diagnosis is delayed. Most paratesticular mesotheliomas arise in the tunica vaginalis, but primary tumors of the spermatic cord and epididymis are also on record. Tumors arising from the peritoneal mesothelium of a hernia sac are excluded from this group. The correct diagnosis is almost always made after histologic examination of the operative specimen. Immunohistochemistry and electron microscopy are always helpful and sometimes necessary tools for diagnosis. So far very few cases have been identified or suspected preoperatively on cytologic examination. Three clinicopathologic types of malignant mesotheliomas of the male genital tract are recognized: diffuse tubulo-papillary mesothelioma, well-differentiated papillary mesothelioma, and multicystic mesothelioma. The histologic subtypes are almost always pure epithelial or biphasic. The differential diagnosis is mainly with serous papillary tumors arising from Mullerian vestiges, but several diverse primary or secondary tumors also need to be considered. A clinicopathologic evaluation of a case of tunical diffuse mesothelioma in a 74-year-old male from the AMR Series is the starting point for this general review.

Asbestos Exposure and Gestational Trophoblastic Disease: A Hypothesis

Among 2,968 women and girls exposed to crocidolite (blue asbestos) at Wittenoom, three cases of choriocarcinoma and three cases of hydatidiform mole have been identified (crude incidence rate of 9.9 per 1000 women and 1.7 per 1000 deliveries for choriocarcinoma and hydatidiform mole, respectively). The women with choriocarcinoma were resident at Wittenoom at the time of disease development, whereas hydatidiform mole occurred much later in women who had first been exposed to asbestos as young girls. Four of the six cases were known to have lived with asbestos company workers who brought their dusty work-clothes home for washing. Asbestos fibers have been reported in the lung, the pleural and peritoneal mesothelium, and the human ovary. They have also been detected in placental digests of live and stillborn infants. This cluster of gestational trophoblastic diseases has some biological plausibility for asbestos causation. Taking an occupational and residential history and examining pathologic specimens for asbestos fibers or bodies may prove useful in patients with gestational trophoblastic disease.

Peritoneal pseudomyxoma

The authors report a case of Pseudomyxoma Peritonei (PP) which was referred to their attention. PP is a rare pathology which is manifested by an autonomous growth of amorphous mucous material in the peritoneal cavity and serosa. PP may be caused by the perforation of a "mucinous cystoadenoma" with secretion of cellular material capable of implanting itself and spreading throughout the peritoneal cavity, or the presence of a mucocele of the appendix, or lastly the possibility of the intrabdominal transformation of the peritoneal mesothelium into mucin-secreting tissue.

Senescent Peritoneal Mesothelial Cells Promote Ovarian Cancer Cell Adhesion: The Role of Oxidative Stress-Induced Fibronectin

Adhesion of ovarian cancer cells to the peritoneal mesothelium is a key step in the malignant progression of the disease. In an in vitro study, we showed that the adherence of ovarian cancer cells (of the OVCAR-3, SKOV-3, and A2780 cell lines) to senescent human omentum-derived peritoneal mesothelial cells (HOMCs) was greater than to early passage cells. The process was mediated primarily by the increased interaction of the alpha5beta1 integrin on cancer cells with HOMC-associated fibronectin (FN). In comparison with early passage HOMCs, senescent cells exhibited increased FN mRNA expression levels and produced significantly more FN. To assess the effect of senescence-associated oxidative stress on FN release, HOMCs were rendered senescent by exposure to an oxidant, tert-butyl hydroperoxide. Treatment with tert-butyl hydroperoxide resulted in a significant increase in HOMC FN mRNA and protein expression levels. The effect of oxidative stress on FN synthesis was found to be mediated by transforming growth factor-beta1, whose signaling pathway was controlled at upstream and downstream levels by p38 MAPK. The activity of p38 MAPK increased markedly in senescent HOMCs. Treatment of HOMCs with antioxidants significantly attenuated senescence-associated increases in p38 MAPK activity, production of both transforming growth factor-beta1 and FN, and ovarian cancer cell adhesion. These data indicate that oxidative stress that accompanies senescence may increase FN production by HOMCs and thus facilitate binding and dissemination of ovarian cancer cells.

HGF and BMP-7 Ameliorate High Glucose–Induced Epithelial-to-Mesenchymal Transition of Peritoneal Mesothelium

Over time, peritoneal dialysis results in functional and structural alterations of the peritoneal membrane, but the underlying mechanisms and whether these changes are reversible are not completely understood. Here, we studied the effects of high levels of glucose, which are found in the dialysate, on human peritoneal mesothelial cells (HPMCs). We found that high concentrations of glucose induced epithelial-to-mesenchymal transition (EMT) of HPMC, suggested by decreased expression of E-cadherin and increased expression of alpha-smooth muscle actin, fibronectin, and type I collagen and by increased cell migration. Normalization of glucose concentration on day 2 reversed the phenotypic transformation, but the changes were irreversible after 7 d of stimulation with high glucose. In addition, exposure of HPMC to high glucose resulted in a decreased expression of the antifibrotic cytokines, hepatocyte growth factor (HGF) and bone morphogenic protein 7 (BMP-7). Exogenous treatment with HGF resulted in a dosage-dependent prevention of high glucose-induced EMT. Both BMP-7 peptide and gene transfection with an adenoviral vector of BMP-7 also protected HPMCs from EMT. Furthermore, adenoviral BMP-7 transfection decreased peritoneal EMT and ameliorated peritoneal thickening in an animal model of peritoneal dialysis. In summary, high concentrations of glucose induce a reversible EMT of HPMCs, associated with decreased production of HGF and BMP-7. Treatment of HPMCs with HGF or BMP-7 blocks high glucose-induced EMT, and BMP-7 ameliorates peritoneal fibrosis in an animal model of peritoneal dialysis.

Peritoneal Mesothelial Cells as a Target of Local Aldosterone Action: Upregulation of Connective Tissue Growth Factor Expression via Serum- and Glucocorticoid-Inducible Protein Kinase 1

Background/Aims: Peritoneal fibrosis can lead to the discontinuation of continuous ambulatory peritoneal dialysis. The present study investigated the direct effect of aldosterone, which influences tissue fibrosis, and its cellular mechanism using cultured rat peritoneal mesothelial cells (RPMCs). Materials andMethods: The expression of aldosterone synthase (CYP11B2), mineralocorticoid receptors, 11β-hydroxysteroid dehydrogenase 2, serum- and glucocorticoid-inducible protein kinase 1 (SGK1) and connective tissue growth factor (CTGF) was evaluated using reverse transcriptase-polymerase chain reaction and Western blot. The ability of RPMCs to produce aldosterone was examined by enzyme immunoassay. Small interfering RNA of SGK1 was transfected to determine the role of SGK1. Results: CYP11B2, mineralocorticoid receptors and 11β-hydroxysteroid dehydrogenase 2 were expressed in RPMCs. The release of aldosterone from RPMCs into the culture medium was confirmed. Stimulation of RPMCs with the addition of aldosterone significantly increased SGK1 expression and phosphorylation and CTGF upregulation, and these effects were completely inhibited by the mineralocorticoid receptor antagonist spironolactone. SGK1 gene silencing abrogated aldosterone-induced CTGF expression. Conclusion: The local aldosterone system exists and acts directly as a profibrotic factor in the peritoneal mesothelium.

Induction of mesothelioma by a single intrascrotal administration of multi-wall carbon nanotube in intact male Fischer 344 rats

The present study assessed a carcinogenic hazard of multi-wall carbon nanotube (MWCNT) in intact (not genetically modified) rodents. MWCNT (1 mg/kg body weight, 7 animals), crocidolite (2 mg/kg body weight, 10 animals) or vehicle (2% carboxymethyl cellulose, 5 animals) was administered to male Fischer 344 rats (12 weeks old) by a single intrascrotal injection. Rats were autopsied immediately after death, when becoming moribund or at the end of the maximal observation period scheduled to be 52 weeks. After 37-40 weeks, however, 6 MWCNT-treated animals died or became moribund due to intraperitoneally disseminated mesothelioma (6/7, 85.7%) with bloody ascites. Peritoneal mesothelium was generally hypertrophic, and numerous nodular or papillary lesions of mesothelioma and mesothelial hyperplasia were developed. While mesothelioid cells were predominant in relatively early stage tumors, advanced stage mesotheliomas were constituted by 2 portions occupied by mesothelioid cells on the surface and spindle-shaped sarcomatous cells in the depth. In the latter, the histological transition was apparently observed between these 2 portions. Mesotheliomas were invasive to adjacent organs and tissues, and frequently metastasized into the pleura. Only 1 rat survived for 52 weeks in the MWCNT-treated group, and similar findings except mesothelioma were observed. All 10 crocidolite-treated and 5 vehicle-treated rats survived for 52 weeks without any particular changes except deposition of asbestos in the former case. It is thus indicated that MWCNT possesses carcinogenicity causing mesothelioma at a high rate in intact male rats under the present experimental conditions. The present data identifies a carcinogenic hazard of MWCNT and will serve as one of the indispensable evidences to be used for the risk assessment crucial for not only protection and improvement of human health and welfare, but also safe and acceptable development and prevalence of this and similar upcoming materials.

Normal saline induces oxidative stress in peritoneal mesothelial cells

Background Peritoneal adhesions are the most common complication of the abdominal surgery. Normal saline is frequently used to rinse the peritoneal cavity during abdominal surgery, although there is no well-established data describing effect of such procedure on the process of formation of peritoneal adhesions. Methods Effect of 0.9% NaCl solution on viability, oxidative stress, and fibrinolytic activity of human peritoneal mesothelial cells maintained in in vitro culture was evaluated. Results Exposure of mesothelial cells to 0.9% NaCl induces oxidative stress, derangement of their structure with subsequent increased release of tissue factor (+75%) and plasminogen activator inhibitor-1 (+19%), and simultaneous suppression of tissue plasminogen activator release (−39%). In effect, ration tissue plasminogen activator/plasminogen activator inhibitor-1 was reduced in 0.9% NaCl-treated cells by 50%. Pretreatment of cells with precursor of glutathione synthesis: l-2-oxothiazolidine-4-carboxylic acid prevented these changes. Conclusions Oxidative stress in the peritoneal mesothelium caused by 0.9% NaCl activates their procoagulant activity and impairs fibrinolytic properties of these cells. These effects disqualify 0.9% NaCl as rinsing solution during abdominal surgery.

Vascular Endothelial Growth Factor Expression in Peritoneal Mesothelial Cells Undergoing Transdifferentiation

To analyze gene expression of localized peritoneal tissue structures in a rodent model of peritoneal fibrosis. Female Sprague Dawley rats were treated with an intraperitoneal injection of an adenovirus expressing active transforming growth factor-beta or control adenovirus. Four and 7 days after infection, animals were sacrificed and frozen sections of parietal peritoneum were subjected to immunofluorescence-aided laser capture microdissection in order to isolate vascular, mesothelial, and submesothelial structures. RNA was extracted from microdissected tissue and gene expression was analyzed by quantitative reverse-transcript polymerase chain reaction. We analyzed genes involved in angiogenesis, epithelial-to-mesenchymal transdifferentiation, and fibrosis. Vascular endothelial growth factor and alpha-smooth muscle actin expression was analyzed with immunohistochemistry of formalin-fixed tissue. Transforming growth factor-beta(1) induced expression of Snail and alpha-smooth muscle actin genes in the peritoneal mesothelium. This same cell population also demonstrated increased gene expression of vascular endothelial growth factor. The distribution of this growth factor was confirmed by immunohistochemistry. The fibrogenic growth factor, connective tissue growth factor, was also strongly induced in the peritoneal mesothelium. Using immunofluorescence-aided laser capture microdissection, we were able to study gene expression in subcompartments of the peritoneal tissue. We demonstrated that mesothelial cells exhibiting mesenchymal transdifferentiation are associated with increased expression of genes associated with fibrosis and angiogenesis.

Vitronectin and Its Receptors Partly Mediate Adhesion of Ovarian Cancer Cells to Peritoneal Mesothelium in vitro

Epithelial ovarian cancer cells metastasize by implanting onto the peritoneal mesothelial surface of the abdominal cavity. Adhesive molecules that lead to this implantation remain unclear. The aim of our study was to focus on the role of vitronectin (Vn) and its receptors, α_v integrins and urokinase plasminogen activator receptor (uPAR), in the interactions of ovarian adenocarcinoma cells (IGROV1 and SKOV3 cell lines) with mesothelial cells (MeT-5A cell line and primary cultures). For all cell lines, immunofluorescence staining disclosed the presence of Vn over the whole cell surface and in thin continuous deposits underlining the cell periphery. Recruitment of Vn receptors to cell-cell contact sites was also revealed. We developed two distinct methods for the evaluation of in vitro cell-cell adhesion using cocultures of the tumor and mesothelial cells. Both adhesion assays revealed a strong ability of ovarian cancer cells to adhere preferentially to mesothelial intercellular junctions. Adhesion of ovarian carcinoma cells to mesothelial cells was significantly inhibited using anti-Vn-, -α_v-integrin- and -uPAR-blocking antibodies or cyclic peptide cRGDfV. These results evidence the ability of ovarian carcinoma cells to bind to peritoneal mesothelium in vitroand strongly suggest that Vn and its receptors contribute to this crucial event.

Increased Dialysate Levels of Phospholipids Containing Unsaturated Fatty Acid Are Associated with Increased Peritoneal Transport Rate

High peritoneal transport status in end-stage renal disease patients receiving peritoneal dialysis was shown to be associated with increased morbidity and mortality. Although the pathogenesis of increased peritoneal transport is still not clear, previous studies have demonstrated that phospholipids (PLs) are present on the peritoneal mesothelium and when added to dialysate can decrease the peritoneal fluid absorption rate and increase peritoneal fluid removal. In the present report, we explored the relationship between peritoneal transport and dialysate loss of endogenous PLs.We evaluated 48 prevalent continuous ambulatory peritoneal dialysis patients with high or low peritoneal transport in a cross-sectional study. The 4-hour dwell dialysate PL profile was analyzed by high-performance liquid chromatography coupled with electrospray ionization ion trap mass spectrometry. The patients' peritoneal small solute transport rate was assessed by D/P(Cr) at 4 h and their fluid transport by kinetic modeling.While there were no significant differences between the 2 groups in age, sex, diabetic status and time on dialysis, high transporters had a significantly higher D/P(Cr) and peritoneal fluid absorption rate (K(e)) than low transporters. The PLs in dialysate effluents mainly consisted of PLs containing unsaturated fatty acid, and the concentrations, as well as the amount, of PLs were significantly elevated in the dialysate of high transporters as compared to low transporters.Our results showed that dialysate from high transporters exhibited elevated levels of PLs, especially PLs containing unsaturated fatty acid, suggesting a possible loss of peritoneal surface-active PLs in peritoneal dialysis, and this loss may contribute to the alteration in peritoneal transport.