Functional characteristics of bronchial epithelium obtained by brushing from asthmatic and normal subjects

Airways epithelial cells may be involved in the pathogenesis of asthma, but their role remains to be determined. Epithelial cells can release large amounts of 15-hydroxy-eicosatetranoic acid (15-HETE) and smaller amounts of prostaglandin E2 (PGE2) as well as fibronectin, a mediator involved in epithelial repair after injury. Epithelial cells obtained after bronchial brushing of 16 asthmatic (age 38 +/- 5 yr) and 11 normal subjects (age 36 +/- 5 yr) were studied. The percentage of epithelial cells was assessed by immunocytochemistry using an anti-cytokeratin antibody. The viability of the cells was assessed by trypan blue exclusion. The release of 15-HETE PGE2 and fibronectin was studied in resting cells and after A23187 calcium ionophore stimulation. Epithelial cells always comprised more than 86% of cells recovered, and the viability of epithelial cells was significantly (p < 0.001, Mann-Whitney U test) greater in normal subjects (54 +/- 5%) compared with asthmatic subjects (13 +/- 1%). The release of 15-HETE and fibronectin by resting epithelial cells was significantly greater in asthmatics (p < 0.05, Mann-Whitney U test) than in normal subjects. A23187 significantly (p < 0.05, Wilcoxon W test) increased the release of 15-HETE and fibronectin. There was no significant difference in the release of PGE2 by resting cells from either asthmatics or normal subjects, but challenge with A23187 induced a significant (p < 0.03, Wilcoxon W test) increase in PGE2 from cells of asthmatics but not from cells of normal subjects. This study shows that epithelial cells are activated and less viable in asthma and suggests a role for these cells in asthma.

Interferon gamma regulation of de novo protein synthesis in human dermal fibroblasts in culture is anatomic site dependent

The propensity of the skin of the lower anterior leg to be involved in Graves' dermopathy prompted an examination of the specific protein synthesis and response to interferon gamma in cultured fibroblasts from this area. Confluent cultures from normal skin of the lower leg and from the abdomen of the same three donors were pulse labeled with [35S]methionine for 3 h and subjected to two-dimensional protein gel electrophoresis and fluorography. Protein spots were mapped using a computer-driven program and the relative densities of the resolvable spots analyzed. Fibroblasts from the two anatomic sites display distinct patterns of de novo protein synthesis. Of the 157 abundant spots arbitrarily chosen for analysis, 31% varied substantially in levels of expression between the sites. A number of proteins appear to be expressed only in cultures derived from one of the two anatomic sites. Interferon gamma (100 U/ml) present in the culture medium for 48 h influenced the abundance of a number of proteins in a site-specific manner. Among them, plasminogen activator inhibitor type-1 was induced three to five times in the leg cultures, whereas this same polypeptide was down-regulated in abdominal fibroblasts. A 54-kD protein was induced in interferon-treated cultures from both sites at least 50 times. It appears that fibroblasts from different regions of the integument are intrinsically distinct in terms of both their protein synthetic programs and their responses to cytokines.

The adverse effect of fibrin-clot inhibiting drugs on intravesical bacillus Calmette-Guérin efficacy for superficial bladder cancer

Bacillus Calmette-Guérin (BCG) is currently thought to act as a biological immune modifier in effecting antitumour activity. Recent evidence suggests that BCG binding to fibronectin (FN), a tissue glycoprotein, may be a prerequisite step in initiating this response. Drugs inhibiting the availability of exposed FN in the bladder after urothelial disruption may adversely affect the efficacy of BCG. Data are presented of 45 patients with tumour limited to mucosa (pTa) or carcinoma in situ (CIS) given intravesical BCG therapy, with (group 1) or without (group 2) fibrin clot-inhibiting drugs concurrently during treatment. The success rate of 11.1% for group 1 (1/9) patients was significantly less than that of 69.4% for group 2 (25/36), (chi 2 = 7.79, P < 0.01 Fisher's exact test) supporting the suggestion that the concurrent administration of fibrin-clot inhibiting drugs may adversely affect the outcome of BCG therapy.

Effect of retinyl acetate on the assembly of the fibronectin extracellular matrix and the processing of the fibronectin receptor beta subunit of confluent C3H/10T1/2 mouse embryo fibroblasts

The mouse embryo fibroblast cell line, C3H/10T1/2, synthesized and deposited a large amount of fibronectin especially in the pericellular matrix. Confluent cultures of these cells cultured in the presence of 0.3 micrograms/ml of retinyl acetate released cell surface fibronectin and the extracellular matrix fibronectin fibrils were disorganized. The immunoblot analysis demonstrated that the number of the fibronectin receptor was decreased in the prolonged culturing of retinyl acetate-treated cells. Immunoprecipitation of 35S-methionine pulse-chase labeled cell extracts by antifibronectin receptor antibody indicated that about one-half of the pre-beta subunit was processed and converted to the mature form in control cells, and only about one-fourth of the pre-beta subunit was processed in the retinyl acetate-treated confluent cells. 1-deoxymannojirimycin (MNJ), which is an inhibitor of oligosaccharide processing, induced disorganization of the extracellular matrix fibronectin assembly similar to that observed with retinyl acetate. The results of this study suggest that a mechanism of action of retinyl acetate is inhibition of the glycosylation during processing of the fibronectin receptor, a step necessary for fibronectin binding and for assembly of the extracellular matrix.

Immunohistochemical distribution of extracellular matrix proteins as a diagnostic parameter in healthy and diseased gingiva

This study showed histopathological findings of the extracellular matrix in healthy, inflamed, and hyperplastic human gingiva with immunohistochemical techniques. The distribution of collagen types V and VI, as well as of glycoprotein fibronectin, shows that they are extracellular matrix structural components which differentiate the tissue pathology. The orientation of the collagen fibers, the intensity of the fluorescent staining, the thickness of the fibrillar component, and the topographical localization of the connective tissue proteins are important parameters for tissue morphology. Therefore, bacterial deposits and the pharmacodynamic properties of drugs associated with gingival hyperplasia lead to an alteration of the matrix compared to the healthy tissues. This may be important in the tissue pathology in cases when the medical history of the patient is not known, as well as in forensic medicine.

Effects of three antiarthritic drugs on fibronectin and keratan sulfate synthesis by cultured canine articular cartilage chondrocytes

Because articular chondrocytes are a target for drugs that can influence the integrity of cartilage, we investigated the effects of 3 antiarthritic drugs, glycosaminoglycan polysulfate, diclofenac-Na, and S-adenosylmethionine sulfate p-toluenesulfonate on total protein, fibronectin, and DNA synthesis, as well as on extradomain-A fibronectin and keratan sulfate content. Glycosaminoglycan polysulfate stimulated dose-dependent incorporation of [35S]methionine into protein and fibronectin, whereas incorporation of [3H]thymidine into DNA was unaffected. Total fibronectin, extradomain-A fibronectin, and keratan sulfate content were high in chondrocyte cultures treated with glycosaminoglycan polysulfate. In contrast, fibronectin and DNA synthesis, as well as extradomain-A fibronectin and keratan sulfate content were unaffected by diclofenac-Na. S-Adenosyl-methionine decreased dose-dependently the synthesis of fibronectin, as well as the content of fibronectin and keratan sulfate. At the highest concentration of S-adenosyl-methionine tested, findings suggest that cell viability was impaired as assessed by the release of lactate dehydrogenase into the media.

Impaired attachment of hepatocytes to extracellular matrix components after chronic ethanol administration

BACKGROUND

Previous studies have shown that the assembly and properties of the hepatocyte plasma membrane are altered by ethanol administration, indicating possible changes in the receptor-mediated binding of the plasma membrane to extracellular matrix substrates. In the present study, the effects of chronic ethanol consumption on the ability of hepatocytes to attach to various components of the extracellular matrix were investigated.

EXPERIMENTAL DESIGN

Rats were pair-fed for 5 weeks with a liquid diet containing either ethanol (as 36% of total calories) or isocaloric carbohydrate. The effects of ethanol treatment on hepatocyte-extracellular matrix interactions was ascertained by determining the ability of isolated hepatocytes to attach to various extracellular matrix substrates.

RESULTS

The attachment of hepatocytes, isolated from the ethanol-fed rats, to laminin-coated plates was significantly decreased compared with hepatocytes from chow-fed or pair-fed controls. Greater decreases in attachment were seen when higher numbers of hepatocytes were seeded in the plates. Similar inhibitions of attachment were also observed when fibronectin or type I collagen were used as matrices. Time-course cell attachment assays indicated that the maximum extent of attachment rather than the rate of attachment was primarily altered by chronic ethanol feeding. Hepatocytes from the ethanol-fed rats also detached more readily from the matrix-coated plates than those from the controls. A reduced number of functional surface receptors for matrix components is likely the most important factor that accounts for the ethanol-induced impairment of hepatocyte attachment.

CONCLUSIONS

These results indicate that chronic ethanol administration impairs the interactions of hepatocytes with their extracellular matrix and that this defect could lead to alterations of hepatocyte structure and function.

Reorganization of the cytoskeleton and morphological changes induced by 1,25-dihydroxyvitamin D3 in C3H/10T1/2 mouse embryo fibroblasts: relation to inhibition of proliferation

The effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) on cell morphology, the cytoskeleton, and fibronectin were studied in three lines of C3H/10T1/2 mouse embryo fibroblasts in which the antiproliferative effect of the hormone had previously been investigated. We showed that 1,25(OH)2D3 induced morphological changes in the nontransformed C3H/10T1/2 Cl 8 cells, which flattened and spread out markedly. Visualization of actin and tubulin by immunocytochemistry disclosed a reorganization of the microfilament and microtubular systems. 1,25(OH)2D3 also induced an increase in cell-surface-associated fibronectin. These changes were only slight in the transformed cell line C3H/10T1/2 Cl 16 and absent in the transformed C3H/10T1/2 TPA 482 cell line. These effects were correlated with the growth inhibition induced by the hormone, and this suggests a possible relationship between the 1,25(OH)2D3-induced alterations of cell shape and of the cytoskeleton and the effects of the hormone on cell proliferation.

Adrenocorticotrophic hormone fails to alter plasma fibrinogen and fibronectin values in calves but does so in rabbits

The intramuscular administration of adrenocorticotrophic hormone (ACTH) to calves, in either a short-acting form (cosyntrophin) or a longer-acting form (ACTHAR Gel), failed to induce any alteration in circulating fibrinogen or fibronectin values, despite marked elevations in plasma cortisol concentrations. With the longer-acting ACTH, plasma cortisol was elevated for at least 12 h following treatment and induced the expected physiological response of an elevation in blood glucose. In contrast, both forms of ACTH induced marked increases (p < 0.01) in plasma fibrinogen and fibronectin when administered to rabbits. The elevation in the circulating levels of these proteins was first observed 24 h after ACTH administration, by which time plasma corticosteroid values had returned to pre-treatment values. With both ACTH preparations the increases in the circulating levels of these proteins were sustained for at least 96 h. The results suggest that, in cattle, the well-recognized increases in plasma fibrinogen values following stress are not associated with the concomitant increase in plasma cortisol. Further, the results clearly illustrate the marked species differences in the response of acute-phase reactant proteins to elevated glucocorticoids.

Blood coagulation, fibrinolytic and inhibitory profiles in renal transplant recipients: comparison of cyclosporine and azathioprine

Renal transplant recipients treated with cyclosporine (CS) have been reported to be at increased risk of thrombotic complications. The present study was intended to examine the blood coagulation, fibrinolytic, and inhibitory systems in such patients. Eight transplant recipients on maintenance immunosuppression with CS and prednisone were studied. Five transplant recipients maintained on azathioprine (AZA) and prednisone and 32 normal volunteers served as controls. Plasma antigen concentrations and/or activities of various proteins in the above pathways were measured. Both the CS and AZA groups exhibited significant elevations of factor IX activity, von Willebrand factor (vWF), D-dimer, protein C and tissue type plasminogen activator (t-PA) levels when compared with the normal controls. In addition, CS group showed a significant elevation of alpha 2-macroglobulin activity and AZA group showed a significant reduction in factor XII activity when compared with the normal controls. Comparison of data from CS and AZA groups revealed higher factor XII activity and vWF concentration in the former group. In conclusion, transplant recipients treated with long-term cyclosporine and prednisone exhibited significant elevation of plasma vWF, D-dimer and protein C concentrations. In addition, both CS and AZA-treated transplant recipients showed increased plasma concentrations of D-dimer and t-PA. The latter observations suggest in vivo thrombin generation, fibrin formation and degradation.

In vitro particulate adherence to fibronectin: correlation with in vivo particulate adherence to sites of bladder injury

This study examined the role of fibronectin in promoting particulate attachment to sites of urothelial injury. Variables influencing adherence of the rat transitional carcinoma cell line 4909 and "non-cellular" styrene-divinylbenzene microspheres to fibronectin were studied in an in vitro system. A soluble synthetic peptide fragment (Gly-Arg-Gly-Asp-Ser [GRGDS]) duplicating the receptor binding domain of fibronectin (RGD) was used to determine whether cell adherence could be inhibited by fibronectin receptor blockade. In vitro findings were correlated with an in vivo assay of both cellular and non-cellular particulate adherence to injured urothelium. Time, plated cell density, substrate concentration, GRGDS concentration, and cell viability, were all found to be significant independent variables influencing in vitro cellular adherence (p less than 0.0001). Receptor blockade with GRGDS significantly decreased in vitro tumor cell adherence to fibronectin. In vitro microsphere binding increased as a direct function of fibronectin concentration but was not time dependent (p less than 0.0001 and p = 0.14 for fibronectin concentration and time respectively). The in vivo adherence of both tumor cells and microspheres was significantly increased in injured bladders compared to controls (p less than 0.01). Receptor blockade with GRGDS failed to inhibit in vivo cell adherence to sites of urothelial injury. Microspheres proved to be competitive inhibitors of cellular adherence in competitive binding assays. In vitro microsphere binding demonstrated a pH dependence with maximal binding at pH 7.2. These data suggest that in vitro tumor cell adherence to fibronectin differs from in vivo tumor cell adherence to sites of urothelial injury. Manipulations which inhibit in vitro adherence, specifically fibronectin receptor blockade and cell death, fail to effect in vivo binding to the extreme that non-cellular particulate appears to bind to the same site, and with similar affinity, as cellular particles.

The biological effects of fluoride on tooth development: possible use of cell culture systems

The action of fluoride on tooth development and the observed side-effects of fluorosis are not yet fully understood. The authors briefly review the literature relating to hypotheses on dental fluorosis and describe in vitro cell culture techniques which could help to clarify the biological effect of fluoride on dental pulpal cells.

Increased adherence of monocytes to fibronectin in bronchiectasis. Regulatory effects of bacterial lipopolysaccharide and role of CD11/CD18 integrins

Regulated adherence of monocytes to extracellular matrix is a prerequisite for accumulation of mononuclear phagocytes during pulmonary infection and inflammation. We have obtained monocytes from patients with an inflammatory lung disease (bronchiectasis) and from control subjects and have compared their adherence to fibronectin. Spontaneous adherence of monocytes from the control subjects was 20 +/- 2%, whereas that of patients' cells was markedly higher and correlated with the severity of airway inflammation: 65 +/- 5% and 40 +/- 8% in patients with purulent and mucoid sputum, respectively. Endotoxin and cytokines from areas of airway disease are likely to be responsible for the observed monocyte activation, since: (1) endotoxin was detectable in all of the patients but in none of the control subjects; (2) LPS produced a dose-related increase in adherence of normal monocytes in vitro (maximal 65 +/- 2% adherence at 1 microgram/ml of LPS); (3) recombinant cytokines and LPS produced additive effects on monocyte adherence in vitro. The adherence of the patients' monocytes to fibronectin was substantially mediated by CD11/CD18 integrins, via both RGD-dependent and RGD-independent mechanisms. These data indicate that signals arising from foci of infection and inflammation can influence the adherence of monocytes, and they are likely to be determinants of the accumulation of mononuclear phagocytes in the lungs of patients with bronchiectasis.

[The plasma fibronectin content and its significance in patients with bronchial asthma]

Reduction of the content of fibronectin in blood plasma depending on severity and form of the disease was revealed in patients with infection-dependent bronchial asthma. Discreteness of influence of autologous leucocytes upon the concentration of fibronectin in plasma, caused by the factor of hormone dependence of the disease was discovered. It was determined that tactivin recovers capability of leucocytes in the patients with hormone dependent asthma directly (monocytes) or indirectly (Lymphocytes, neutrophils) to produce fibronectin.

Different action of heparin and fucoidan on arterial smooth muscle cell proliferation and thrombospondin and fibronectin metabolism

Fucoidan, a sulfated fucopolysaccharide of marine algae is able to inhibit the proliferation of arterial smooth muscle cells half maximally at a concentration of 80 to 100 micrograms/ml culture medium. In comparable concentrations heparin was significantly less active than the fucopolysaccharide. Sulfation of fucoidan was found to be essential for expression of antiproliferative activity. The inhibitory effect of fucoidan is a time-dependent event with highest effectiveness during the first 6 h. Fucoidan does not influence the overall rate of synthesis of cell proteins and glycoconjugates, but led to substantial alterations in the synthesis and secretion of fibronectin and thrombospondin. Immunoprecipitation and quantitation revealed that the incorporation of [35S]methionine into fibronectin is reduced whereas thrombospondin synthesis was increased. The effect on fibronectin was not shared by heparin. Desulfation of the fucopolysaccharide abolished the observed modulation. Binding experiments with [125I]fucoidan indicate a saturable binding and a maximum of 2.8 x 10(6) bound molecules per cell. Fucoidan binding sites can be only partly displaced by heparin. The results suggest that both heparin and the structurally unrelated sulfated fucopolysaccharide act as an antiproliferative agent but differ in their modulation of cell metabolism.

Analysis of the interaction between human plasma fibronectin and gelatin by affinity electrophoresis

The interaction between human plasma fibronectin and gelatin was analyzed by affinity electrophoresis, in which the fibronectin was subjected to electrophoresis in a 4% polyacrylamide gel in the presence and absence of gelatin, as an affinity ligand, and the fibronectin band was stained by an immunoblotting method. The apparent dissociation constants (Kd) of fibronectin for gelatin were calculated from affinity plots based on the original affinity equation at different pHs, urea concentrations, and temperatures. The fibronectin exhibited much lower affinity in the presence of urea. The Kds at 37 degrees C were 1.49 X 10(-7) M, 2.50 X 10(-6) M, and 3.58 X 10(-6) M with 2 M, 3 M, and 4 M urea, respectively. The van't Hoff plots of Kd values against absolute temperature (T) showed that the value of log Kd decreased in proportion to the increase in the value of 1/T within the range of 15-50 degrees C. The standard enthalpy, the standard free energy change at 37 degrees C, and the entropy change at 37 degrees C for association were calculated to be -124.7 kJ/mol, -33.23 kJ/mol, and -295.1 J/mol/deg, respectively. These results suggest that a hydrophilic interaction, such as hydrogen bond or van der Waals interaction, plays an important role in the binding of plasma fibronectin to gelatin.

Oxidative damage to fibronectin. II. The effect of H2O2 and the hydroxyl radical

The effect of H2O2 and the hydroxyl radical (.OH) on fibronectin was investigated. .OH was generated in three ways: (i) by radiolysis with 60Co under N2O, or by the Fenton system using either (ii) equimolar Fe(2+)-EDTA and H2O2 or (iii) H2O2 and catalytic amounts of Fe(2+)-EDTA recycled with ascorbate. Each system had a different effect. H2O2 alone caused no changes, even at an 800-fold molar excess. Radiolytic .OH caused a rapid loss of tryptophan fluorescence, an increase in bityrosine fluorescence, and extensive crosslinking. The Fenton system using Fe-EDTA, H2O2, and ascorbate caused a loss in tryptophan fluorescence, a smaller increase in bityrosine than was seen with radiolytic .OH, and a threefold increase in carbonyl groups. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis fragmentation of fibronectin was seen. In contrast, when .OH was generated with equimolar Fe-EDTA and H2O2, the only change was a small increase in bityrosine fluorescence at the highest dose of oxidant. None of the systems used affected cysteine. All the changes except the loss of tryptophan by radiolytic .OH were completely inhibited with mannitol. The differences seen with radiolytic .OH and the Fe-EDTA, H2O2, ascorbate system were not solely due to O2 in the latter system since similar results were obtained under N2. The differences between radiolytic .OH and the Fenton systems could be partly due to the components of the latter systems reacting with .OH and thus competing with fibronectin. Our results demonstrate that the extent and type of fibronectin damage by .OH is dependent on the mode of radical generation.

Dose-response studies on the effect of n-3 polyunsaturated fatty acids on lipids and haemostasis

We have studied the dose-response effects of dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA's) on lipids and haemostasis. Ten healthy males were each given 1.3 g, 4 g or 9 g of n-3 PUFA's daily for 6-week periods. Bleeding time, HDL-cholesterol and plasminogen activator inhibitor increased with the dose of n-3 PUFA. Plasma fibrinogen and triglyceride levels were reduced in a dose-dependent fashion. After ingestion of 1.3 g of n-3 PUFA's plasma fibrinogen decreased from 9 to 7 mumol/l and HDL-cholesterol increased from 1.2 to 1.3 mmol/l. The bleeding time was prolonged from 5 to 6.5 min while triglyceride levels decreased from 1.2 to 0.9 mmol/l after ingestion of 4 g of n-3 PUFA's. Dietary supplementation with the highest daily dose (9 g) reduced plasma levels of triglycerides, fibrinogen and von Willebrand factor, while bleeding time, plasminogen activator antigen, plasminogen activator inhibitor and the ratio of HDL-cholesterol to total cholesterol increased.

[The regulation of DNA synthesis by fibronectin and its proteolytic products in the skin fibroblasts of healthy donors and patients with systemic scleroderma and rheumatoid arthritis]

To study the effect of fibronectin isolated from plasma and culture media and the effect of its tryptic hydrolyzates on DNA synthesis, cultured skin fibroblasts of healthy donors and these of patients with systemic scleroderma (SSD) and rheumatoid arthritis (RA) were employed. It was shown that both fibronectin and total products of its proteolysis markedly stimulated DNA synthesis only in skin fibroblasts of patients with SSD. Fibronectin fragments inhibited DNA synthesis in all fibroblast strains studied. The effect of fibronectin and all its Gel fragments on the DNA synthesis in skin fibroblasts of patients with SSD was dose-dependent. The activity of total fibronectin tryptate, Gel-fragment-free tryptate, and Gel fragments themselves depended on the duration of fibronectin proteolysis, i. e. on the size of the fragments obtained. Culture media collected after treatment of fibroblast monolayer with trypsin and subsequent removal of fibronectin Gel fragments had mitogenic effect on skin fibroblasts, especially on those of patients with SSD and RA. It is supposed that fibronectin Gel fragments are inhibitors of growth factors produced by fibroblasts. The results suggest that fibronectin and its fragments have an important regulatory role in fibroblast proliferation.

Fibronectin network recovery in confluent PtK2 cells after acrylamide treatment

Confluent PtK2 cells 4 hr treated with 5 mM acrylamide were FN-detected by indirect immunofluorescence. The initial fibrillar-FN network was replaced by an alveolar-type network located at the cell-cell contacts areas in the form of a thick frame with a lace-like appearance. Afterwards, acrylamide removal was obtained by several washes with fresh FCS-free culture medium. Then, PtK2 cells were returned to the incubator for 20 hr. Cell recovery was indicated by reversion of the initial fibrillar-FN network. These data show that FN reversion was possible without any changes in shape and cytoplasmic organization of non-motile growing cells.