Fibrinogen promotes adhesion of monocytic to human mesothelioma cells.

Adhesion between monocytic and mesothelioma or pleural mesothelial cells influences stromal remodeling in pleural neoplasia. We found that cultured monocytic cells (U937) adhere to either human pleural mesothelioma (MS-1) or mesothelial (MeT5A) cells in vitro. 125I-fibrinogen bound specifically and saturably to either cell line, and specific fibrinogen binding increased upon stimulation of these cells with proinflammatory agents such as phorbol myristate (PMA), lipopolysaccharide (LPS) or tumor necrosis factor (TNF-alpha). We purified the fibrinogen receptor protein from a membrane fraction of MS-1 cells and identified it by immunoprecipitation as intercellular adhesion molecule (ICAM-1). Anti-ICAM-1 antibody or antisense oligonucleotides inhibited fibrinogen-mediated cell adhesion and binding of 125I-fibrinogen to mesothelioma or mesothelial cells. Cultured monocytic cells adhere to either mesothelioma or mesothelial cells, and the interaction is promoted by fibrinogen binding ICAM-1 at the cell surface. ICAM-1 is expressed by mesothelioma cells and CD 11b by macrophages in the fibrinous mesothelioma tumor stroma. The data suggest a common mechanism by which monocytic cells could adhere to either malignant mesothelioma cells or the mesothelial surface in pleural neoplasia.

Tissue factor pathway inhibitor in tetracycline-induced pleuritis in rabbits.

Pleural fibrin deposition that promotes loculation and fibrosis after pleural injury is initiated by tissue factor (TF). In this study, we sought to determine if tissue factor pathway inhibitor (TFPI), an inhibitor of the TF-factor VIIa complex, was likewise expressed in tetracycline (TCN)-induced pleural injury and, if so, whether TFPI was locally elaborated. Pleural fluid TFPI activity approximated that of plasma by 24 h and doubled by 3 days after intrapleural TCN. By contrast, pleural fluid coagulation factors VII and V remained below plasma concentrations at these intervals. Immunohistochemical studies demonstrated TF, TFPI and fibrin localized in pleural and subpleural tissues and within intrapleural adhesions. TFPI activity and mRNA were also elaborated by rabbit pleural mesothelial cells and lung fibroblasts. TFPI is locally expressed and pleural fluid TFPI exceeds plasma levels during TCN-induced pleural injury. Resident cells as well as extravasation likely contribute to intrapleural TFPI. TFPI expression temporally and anatomically approximates that of TF and may limit TF-induced fibrin deposition in evolving TCN-induced pleuritis.

Epithelioid sarcoma of penis.

A case of epithelioid sarcoma of the penis in a thirty-two-year-old man is presented. It had been present for two and one-half years as a small nodule on the ventral aspect at the base of the penis that eventually grew to large dimensions causing pain and extreme dysuria. A local resection was done; however, when tumor recurred, penectomy was undertaken followed by an incomplete course of radiotherapy. Fifteen months after surgery the patient was free of local recurrence but was in poor condition with metastases to regional and distant lymph nodes, lungs, and scalp--a pattern of spread characteristic of these tumors. This is a typical example of epithelioid sarcoma clinically, histologically, and ultrastructurally, despite the rare location.

Thyroid C cells in the DiGeorge anomaly: a quantitative study.

The developmental field defect in the DiGeorge anomaly (DGA) principally affects derivatives of the third and fourth branchial pouches (areas containing a large population of cephalic neural crest cells), including the ultimobranchial body (UB), the reputed source of thyroid calcitonin-producing cells (C cells) in humans. To evaluate the content of C cells in children with DGA, sections of the thyroid in 16 cases of DGA (group I) (8 incomplete and 8 complete forms) and 16 age-matched controls (group II) were stained by immunoperoxidase for calcitonin and chromogranin. Eleven of 16 (69%) cases in group I [4 of 8 (50%) of the complete and 7 of 8 (88%) of of the incomplete cases] and 14 of 16 (88%) of group II exhibited positive-staining cells for both markers, either individually or in small clusters within the follicular epithelial basement membrane. The average number of C cells per high-power field (HPF) (400x) for group I was 1.6 +/- 0.9 and for group II 4.9 +/- 1.7 (P < .005). Although the percentage of positive incomplete DGA cases was the same as that of the control cases, the average number of C cells/HPF was 2.0 +/- 1.1 and similar to that of complete DGA cases (1.2 +/- 0.6). These results demonstrated that C cells are present in the thyroid of patients with DGA more frequently than expected, although in deficient numbers when compared quantitatively to age-matched controls showing a normal infantile pattern of thyroid C cell distribution. Although this observation confirms that there is deficiency of thyroid C cell development in DGA and is in keeping with the assumption that the cells are of neural crest origin, our data raise the possibility of an additional source of C cells, perhaps from thyroid endoderm, in a manner analogous to the endocrine cells of the gut and respiratory tract.

Pseudomelanosis duodeni in an adolescent male: case report and review of the literature.

Pseudomelanosis duodeni is rarely seen in children. It manifests endoscopically as peppery speckles in the duodenal mucosa. This pigment corresponds principally to accumulation of ferrous sulfide in macrophages within the lamina propria. We report the case of a 16-year-old boy with ectodermal dysplasia who underwent renal transplantation for vesicoureteral reflux and later developed epigastric pain. Endoscopic and pathologic findings in the duodenal mucosa were typical of pseudomelanosis duodeni. A review of the literature reveals shared clinical features among reported adult and pediatric cases, including chronic renal failure, use of antihypertensive medication and oral iron supplementation, and/or presence of gastric hemorrhage.

Tissue factor pathway inhibitor expression by human pleural mesothelial and mesothelioma cells.

The mesothelial lining of the pleura and malignant mesothelioma promote fibrin deposition in pleural injury or neoplasia via expression of tissue factor (TF). It was hypothesized that these cells might also regulate intrapleural coagulation by elaborating TF pathway inhibitor (TFPI). TFPI activity and antigen in pleural fluids were assayed from patients with congestive heart failure (CHF), pneumonia, empyema, metastatic pleural cancer and malignant mesothelioma. The authors also assessed expression of TF and TFPI messenger ribonucleic acid (mRNA) as well as TFPI activity and antigen by human pleural mesothelial cells, malignant mesothelioma cells (MS-1 cell line) and human lung fibroblasts. Immunohistochemical analyses of normal, fibrotic, and neoplastic pleura were performed to determine whether TFPI antigen was expressed in vivo. The study revealed that TFPI was present in transudates from patients with CHF and exudative pleural effusions from patients with pneumonia, empyema or pleural carcinoma. TFPI mRNA, activity and antigen were expressed by pleural mesothelial cells, MS-1 cells and lung fibroblasts. Cytokines and serum stimulated a significant early increase in TF mRNA levels with minimal enhancement of TFPI mRNA, activity and antigen levels. TFPI antigen was found in normal, fibrotic and neoplastic pleural tissues. The current observations indicate that tissue factor pathway inhibitor is locally expressed in pleural disease, but that it does not prevent the development of a prothrombotic environment favouring local fibrin deposition in pleural inflammation or cancer.

Urokinase receptor in human malignant mesothelioma cells: role in tumor cell mitogenesis and proteolysis.

Urokinase (uPA) interacts with its receptor (uPAR) to promote proteolysis and tumor migration, functions of potential importance in the pathogenesis of malignant mesothelioma. Immunohistochemistry of human malignant mesothelioma tissue and mesothelioma cells (MS-1) showed that mesothelioma cells express uPAR. We isolated uPAR from MS-1 cells by metabolic labeling and showed that it could be induced by phorbol myristate acetate (PMA), lipopolysaccharide (LPS), a transforming growth factor-beta (TGF-beta) or tumor necrosis factor-alpha (TNF-alpha). Experiments with MS-1 cells showed that uPA binding was saturable, specific, and reversible with a mean dissociation constant (Kd) of 5.4 +/- 1.1 nM. Binding was inhibited by a blocking antibody to uPAR and by the uPA amino-terminal fragment (ATF), but not by low molecular weight uPA. uPAR expression was regulated transcriptionally and translationally; antisense oligonucleotides blocked expression of uPAR protein. Plasminogen activator inhibitor-1 (PAI-1) inhibited PA activity of preformed uPA/uPAR complexes and increased cycling of the receptor from the cell surface. Stimulation of subconfluent MS-1 cells by high molecular weight or recombinant uPA, but not ATF or low molecular weight fragment, caused concentration-dependent incorporation of [3H]thymidine. These data indicate a novel mechanism by which malignant mesothelioma cells localize pericellular proteolysis and concurrently regulate tumor cell proliferation.

Differential expression of the urokinase receptor in fibroblasts from normal and fibrotic human lungs.

Binding of urokinase-type plasminogen activator (uPA) to a specific receptor (uPAR) on human lung fibroblasts enables it to regulate cellular proteolysis and remodeling of the extracellular matrix. Binding studies with radiolabeled uPA indicated that both normal and fibrotic lung fibroblasts express the receptor, but cells from fibrotic tissues bound significantly more uPA (P < 0.001). Phorbol myristate acetate, lipopolysaccharide, transforming growth factor-beta (TGF-beta), and tumor necrosis factor-alpha (TNF-alpha) increased uPA binding and plasminogen activation at the cell surface, with a greater maximal effect on fibrotic than on normal fibroblasts. Excess unlabeled uPA, specific antibody, or antisense oligonucleotides inhibited uPA binding. Ribonuclease (RNase) protection assays showed higher levels of uPAR messenger ribonuleic acid (mRNA) in each of the five fibrotic cell lines than in normal fibroblasts. uPA was mitogenic for normal as well as fibrotic fibroblasts, indicating that receptor binding concurrently localizes cellular proteolytic activity and stimulates mitogenesis. Morphometry and immunohistochemical analysis showed that uPAR, as well as uPA, was increased in fibroblasts in fibrotic lung tissue. Increased expression of uPAR by fibrotic lung fibroblasts and enhanced urokinase binding induced by proinflammatory cytokines suggest a novel mechanism by which fibroblast-mediated matrix remodeling and proliferation may be regulated in interstitial lung diseases.

Chemokine involvement in tetracycline-induced pleuritis.

Sclerosants such as tetracycline (TCN) have often been used in the control of malignant pleural effusions. Although the resultant inflammatory response is probably important in the ensuing pleural fibrosis, the signals responsible for the cellular influx into the pleural space following TCN instillation are not well understood. This study, therefore, sought to determine whether the chemokines interleukin-8 (IL-8), growth-related protein (Gro), and monocyte chemotactic protein-1 (MCP-1) were locally elaborated within the first 72 h following intrapleural TCN administration. TCN induced an exudative effusion with high lactate dehydrogenase activity. Although there was no significant change in the pleural fluid total leukocyte content, the median polymorphonuclear neutrophil concentration decreased from 1.067x10(6) to 2.03x10(5) cells x mL(-1) between 24 and 72 h, whereas the median macrophage concentration increased from 1.44x10(5) to 5.98x10(5) cells x mL(-1) over the same period. Furthermore, IL-8, Gro and MCP-1 concentrations decreased between 24 and 72 h. Immunocytochemistry indicated expression of IL-8 by pleural mesothelial cells 24 h, but not 72 h, following TCN administration. The data suggest that local elaboration of interleukin-8 and growth-related protein, in part of mesothelial origin, may influence neutrophil recruitment in tetracycline-induced pleuritis.

Regulation of fibrin deposition by malignant mesothelioma.

Malignant mesothelioma (MM) is a locally aggressive tumor that spreads by poorly understood mechanisms. Because neoplastic spread has been linked to altered fibrin turnover, we used immunohistochemistry of nine MM and three fibrous tumors of the pleura to confirm in vivo fibrin deposition and expression of selected coagulation and fibrinolytic reactants in MM. Tumor-associated fibrin was readily detectable at site of tissue invasion. Little fibrin was distributed within the tumor, but tissue factor and tissue factor pathway inhibitor, urokinase, urokinase receptor, and plasminogen activator inhibitors 1 and 2 were all detected in either epithelioid or sarcomatous areas of MM. We used the MS-1 human pleural mesothelioma cell line to determine how expression of these reactants is regulated. Fibrinolytic activity of MS-1 is mainly due to urokinase and is responsive to cytokine stimulation. Functional extrinsic activation and prothrombinase complexes assemble at the cell surface. MM express procoagulants as well as fibrinolytic reactants in vivo and in vitro that promote local fibrin formation and remodeling. Fibrin deposition occurs primarily at areas of tissue invasion and could promote local extension of this neoplasm. Sparsity of fibrin within the central portions of the tumor stroma suggests that local resorption of transitional fibrin occurs at sites of established MM.