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J R Hoidal

Publications and source records attributed to J R Hoidal.

At least 73 records · Page 4Linked to original sources
PubMed1993

Metalloproteinases and tissue inhibitor of metalloproteinases in mesothelial cells. Cellular differentiation influences expression.

Mesothelial cells play a critical role in the remodeling process that follows serosal injury. Although mesothelial cells are known to synthesize a variety of extracellular matrix components including types I, III, and IV collagens, their potential to participate in matrix degradation has not been explored. We now report that human pleural and peritoneal mesothelial cells express interstitial collagenase, 72- and 92-kD gelatinases (type IV collagenases), and the counterregulatory tissue inhibitor of metalloproteinases (TIMP). Our initial characterization of the mesothelial cell metalloenzymes and TIMP has revealed: (a) they are likely identical to corresponding molecules secreted by other human cells; (b) they are secreted rather than stored in an intracellular pool; (c) a primary site of regulation occurs at a pretranslational level; (d) phorbol myristate acetate, via activation of protein kinase C, upregulates expression of collagenase, 92-kD gelatinase, and TIMP, but has no effect on expression of 72-kD gelatinase; and (e) lipopolysaccharide fails to upregulate the biosynthesis of either metalloproteinases or TIMP. Of particular interest is the observation that the state of cellular differentiation has a striking influence on the expression of metalloenzymes and TIMP, such that epitheloid cells display a more matrix-degradative phenotype (increased 92-kD gelatinase and decreased TIMP) than their fibroblastoid counterparts. We speculate that mesothelial cells directly participate in the extracellular matrix turnover that follows serosal injury via elaboration of metalloproteinases and TIMP. Additionally, the reactive cuboidal mesothelium which is characteristic of the early response to serosal injury may manifest a matrix-degenerative phenotype favoring normal repair rather than fibrosis.

Adult↗
PubMed1992

Human neutrophil proteinase 3: mapping of the substrate binding site using peptidyl thiobenzyl esters.

A series of peptidyl thiobenzyl esters was used to map the active site of human leukocyte proteinase 3. The steady-state kinetics parameters reveal the following features regarding the substrate specificity of proteinase 3 and its putative active site: (a) the preferred P1 residue is a small hydrophobic amino acid such as aminobutyric acid, norvaline, valine or alanine (in decreasing order of preference); (b) the enzyme has an extended active site; and (c) its active site is similar to that of the related serine proteinases leukocyte elastase and leukocyte cathepsin G.

Amino Acid Sequence↗
PubMed1992

Structure, chromosomal assignment, and expression of the gene for proteinase-3. The Wegener's granulomatosis autoantigen.

Proteinase-3 (PR-3) is a neutral serine proteinase present in the azurophil granules of human polymorphonuclear leukocytes. It degrades a variety of extracellular matrix proteins including elastin in vitro and causes emphysema when administered by tracheal insufflation to hamsters. It is identical to the target autoantigen (c-ANCA) associated with Wegener's granulomatosis and to myeloblastin, a serine proteinase first identified in HL-60 leukemia cells. In this study, the gene encoding PR-3 was cloned and sequenced. The gene spans approximately 6.5 kilobase pairs and consists of five exons and four introns. The genomic organization of PR-3 is similar to that of the other serine proteinases expressed in hemopoietic cells. Each residue of the catalytic triad of PR-3 is located on a separate exon, and the positions of the residues within the exons are similar to those in human leukocyte elastase and cathepsin G. The phase and placement of the introns in the PR-3 gene are also similar to those in human leukocyte elastase and cathepsin G. The 400-base pair (bp) 5'-flanking sequence of the PR-3 gene contains a TATA box at position 379. There is no CAAT box promoter element. The 3'-untranslated region is 200 bp, extending from a TGA stop codon to the site of polyadenylation 10 bp after the canonical AATAAA signal. Amplification of PR-3 from a human/hamster hybrid cell line localizes the gene to human chromosome 19. Evidence from Northern analysis suggests that PR-3 expression is primarily confined to the promyelocytic/myelocytic stage of bone marrow development.

Amino Acid Sequence↗
PubMed1992

Pulmonary epithelial cell urokinase-type plasminogen activator. Induction by interleukin-1 beta and tumor necrosis factor-alpha.

Diffuse alveolar damage, presenting clinically as adult respiratory distress syndrome, is characterized initially by widespread intra-alveolar fibrin deposition. Alveolar epithelial cells play a central role in the subsequent repair process. We have recently shown that alveolar epithelial cells have the capacity to promote fibrinolysis (Marshall, B. C., Sageser, D. S., Rao, N. V., Emi, M., and Hoidal, J. R. (1990) J. Biol. Chem. 265, 8198-8204) and may therefore directly participate in the extensive remodeling that follows acute lung injury. Because the tissue repair process occurs in an acute inflammatory setting, we investigated the effects of inflammatory mediators on urokinase-type plasminogen activator (u-PA) expression by pulmonary epithelial cells. We found that interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) upregulated PA activity in A549 human pulmonary epithelial cells. Biosynthetic labeling and immunoprecipitation showed that both cytokines caused marked accumulation of newly synthesized u-PA. Northern blot analyses demonstrated that both IL-1 beta and TNF-alpha induced relatively rapid accumulation of u-PA mRNA which did not require de novo protein synthesis and was substantially inhibited by glucocorticoids. Nuclear run-off transcription studies showed that both cytokines caused rapid transcriptional activation of the u-PA gene. While the effects of IL-1 beta and TNF-alpha were qualitatively similar, some differences emerged. Most notably, TNF-alpha led to a more sustained accumulation of u-PA mRNA than did IL-1 beta. In contrast to their effects on u-PA expression, IL-1 beta and TNF-alpha had minimal effect on PA inhibitor-1 expression. These effects of IL-1 beta and TNF-alpha, mediators known to play a key role in acute lung injury and inflammation, may promote lysis of alveolar fibrin by alveolar epithelium, thereby aiding in restoration of normal lung architecture.

Blotting, Northern↗
PubMed1992

Role of surface complexed iron in oxidant generation and lung inflammation induced by silicates.

Inhalation of silicates induces a variety of lung diseases in humans. The molecular mechanism(s) by which these dusts cause disease is not known. Because several naturally occurring mineral oxides have large amounts of transition metal ions on their surfaces, we tested the hypothesis that surface complexation of iron may be an important determinant of their ability to induce disease. Silica, crocidolite, kaolinite, and talc complexed considerable concentrations of Fe3+ onto their surfaces from both in vitro and in vivo sources. The potential biological importance of iron complexation was assessed by examining the relationship between surface [Fe3+] and the ability of silicates to mediate oxidative degradation of deoxyribose in vitro, induce a respiratory burst and elicit leukotriene B4 (LTB4) release by alveolar macrophages (AM) in vitro, and cause acute alveolitis after intratracheal insufflation. For these studies, three varieties of silicate dusts were used: iron-loaded, wetted (unmodified), and deferoxamine-treated to remove Fe3+. The ability of silicates to catalyze oxidant generation in an ascorbate/H2O2 system in vitro, to trigger respiratory burst activity and LTB4 release by AM, and to induce acute lung inflammation in the rat all increased with surface complexed Fe3+. The results of these studies suggest that surface complexation of iron may be an important determinant in the pathogenesis of disease after silicate exposure.

Adsorption↗
PubMed1992

Regulation of xanthine dehydrogenase and xanthine oxidase activity and gene expression in cultured rat pulmonary endothelial cells.

The central importance of xanthine dehydrogenase (XDH) and xanthine oxidase (XO) in the pathobiochemistry of a number of clinical disorders underscores the need for a comprehensive understanding of the regulation of their expression. This study was undertaken to examine the effects of cytokines on XDH/XO activity and gene expression in pulmonary endothelial cells. The results indicate that IFN-gamma is a potent inducer of XDH/XO activity in rat lung endothelial cells derived from both the microvasculature (LMVC) and the pulmonary artery. In contrast, interferon-alpha/beta, tumor necrosis factor-alpha, interleukin-1 or -6, lipopolysaccharide and phorbol myristate acetate have no demonstrable effect. The increase in XDH/XO activity requires new protein synthesis. By Northern analysis, IFN-gamma markedly increases the level of the 5.0-kb XDH/XO mRNA in LMVC. The increase is due, in part, to increased transcription rate of the XDH/XO gene. Transcriptional activation does not require new protein synthesis. The physiologic relevance of these observations was evaluated by administering IFN-gamma to rats. Intraperitoneal administration leads to an increased XDH/XO activity and XDH/XO mRNA level in rat lungs. In sum, IFN-gamma is a potent and biologically relevant inducer of XDH/XO expression; the major site of upregulation occurs at the transcriptional level.

Animals↗
PubMed1991

Characterization of proteinase-3 (PR-3), a neutrophil serine proteinase. Structural and functional properties.

Proteinase 3 (PR-3) is a human polymorphonuclear leukocyte (PMNL) serine proteinase that degrades elastin in vitro and causes emphysema when administered by tracheal insufflation to hamsters (Kao, R. C., Wehner, N. G., Skubitz, K. M., Gray, B. H., and Hoidal, J. R. (1988) J. Clin. Invest. 82, 1963-1973). We have determined the primary structure of several PR-3 peptides and have analyzed catalytic properties of the enzyme. The enzyme has considerable amino acid sequence homology with two other well characterized PMNL neutral serine proteinases, elastase and cathepsin G. Furthermore, the NH2-terminal amino acid sequence of PR-3 is identical to that of the target antigen of the anti-neutrophil cytoplasmic autoantibodies associated with Wegener's granulomatosis. PR-3 degrades a variety of matrix proteins including fibronectin, laminin, vitronectin, and collagen type IV. It shows no or minimal activity against interstitial collagens types I and III, respectively. The analysis of peptides generated by PR-3 digestion of insulin chains and the activity profile against a panel of chromogenic synthetic peptide substrates show that PR-3 prefers small aliphatic amino acids (alanine, serine, and valine) at the P1 site. The elastase-like specificity of PR-3 is consistent with its striking sequence homology to elastase at substrate binding sites. PR-3 is inhibited by alpha 1-proteinase inhibitor (ka = 8.1 x 10(6) M-1 S-1; delay time = 25 ms) and alpha 2-macroglobulin (ka = 1.1 x 10(7) M-1 S-1; delay time = 114 ms) but not by alpha 1-anti-chymotrypsin. In contrast to elastase and cathepsin G, PR-3 is not inhibited by secretory leukoprotease inhibitor and is weakly inhibited by eglin c. Thus, PR-3 is distinct from the other PMNL proteinases.

Amino Acid Sequence↗
PubMed1990

Hypothesis: is lung disease after silicate inhalation caused by oxidant generation?

Inhaled silicate dusts may cause lung disease through their surface coordination of iron with subsequent oxidant generation via the Fenton reaction. Pneumoconiosis, irritant bronchitis, focal emphysema, and carcinoma may be produced by oxidants either directly through lipid peroxidation and protein inactivation, or indirectly by oxidant-mediated release of cytokines such as platelet-derived growth factor. The increased incidence of tuberculosis observed among silicate workers could be explained by accumulation of iron complexed by dust particles in the lung and made available to dormant mycobacteria as a virulence factor.

Dust↗
PubMed1990

Alveolar epithelial cell plasminogen activator. Characterization and regulation.

Intra-alveolar fibrin deposition is one of the pathological hallmarks of acute lung injury. Because alveolar epithelial cells play a central role in the repair process following acute lung injury, this study was undertaken to examine their potential to produce a plasminogen activator (PA). We now report the synthesis and secretion of PA by rat alveolar epithelial cells with the catalytic properties of a urokinase-type (u-PA) rather than tissue-type plasminogen activator. Studies of regulation of epithelial cell u-PA revealed: 1) phorbol myristate acetate (PMA) but not the inactive structural analog 4 alpha-PMA upregulated u-PA synthesis, putatively via the protein kinase C pathway; 2) PMA induction of u-PA activity was substantially inhibited by dexamethasone and completely inhibited by cycloheximide; 3) unstimulated alveolar epithelial cells had no detectable u-PA mRNA, whereas PMA exposure led to activation of the u-PA gene and accumulation of a 2.5-kilobase u-PA mRNA; and 4) cycloheximide did not abolish this induction of u-PA mRNA suggesting that intermediate protein synthesis was not necessary for the activation of transcription. In light of their capacity to promote fibrinolysis and their strategic anatomic location, alveolar epithelial cells are likely to play a key role in the extensive remodelling process that follows acute lung injury.

Amiloride↗
PubMed1990

Hydroxyl radical generating activity of hydrous but not calcined kaolin is prevented by surface modification with dipalmitoyl lecithin.

The catalytic activity of kaolin, an aluminum silicate, for generating hydroxyl radicals (.OH) from hydrogen peroxide (H2O2) was studied in a chemical system that measured .OH as evolution of methane (CH4) from dimethyl sulfoxide. In the presence of a reducing agent and 10 mM H2O2, hydrous and calcined kaolin generated mean +/- SE CH4 concentrations of 1634 +/- 328 and 1395 +/- 29 ppm, respectively. Surface modification with dipalmitoyl lecithin, the lipid of pulmonary surfactant, blocked generation of .OH in hydrous kaolin (38 +/- 38 ppm CH4) but not in calcined kaolin (875 +/- 262 ppm CH4). The catalytic activity of kaolin for producing .OH from H2O2 may be important in the pathogenesis of kaolin toxicity, and calcined kaolin may be more toxic than hydrous kaolin because the calcined form is resistant to surface modification by lipids of pulmonary surfactant.

Humans↗
PubMed1990

Cellularity of the alveolar walls in smokers and its relation to alveolar destruction. Functional implications.

Inflammatory cells are believed to play an important role in the pathogenesis of emphysema; however, a relationship between presence of cells in the lung parenchyma and its destruction has never been shown. The aim of this study was to quantitate alveolar septal cellularity in smokers' lungs and to investigate its relationship with parenchymal destruction and lung function. The lungs of 23 smokers (SS) undergoing thoracotomy for localized pulmonary lesions were compared with those of eight nonsmokers (NS) and five smokers (AS) who died suddenly of nonrespiratory causes. Pulmonary function tests were performed within 1 wk of surgery in SS. For each subject, we quantitated alveolar wall cells (CELLS), an index of alveolar wall destruction (DI), and the mean linear intercept (Lm). As no significant differences were found between S and AS with regard to these indices, we combined them (Group S) for comparison with NS. Although Lm was not significantly different between S and NS, (0.331 +/- 0.072 versus 0.288 +/- 0.038), CELLS and DI were higher in S than in NS (48 +/- 8 versus 25 +/- 2 cells/mm, p less than 0.001; 47 +/- 20 versus 17 +/- 5, p less than 0.001, respectively). Further, CELLS and DI were significantly correlated (r = 0.799, p less than 0.001). The number of polymorphonuclear cells (PMN) in S can exceed that in NS by as much as 5-fold; however, PMN were inversely correlated with parenchymal destruction (DI) (r = 0.598, p less than 0.01). Thus, smokers' lungs have alveolar septal hypercellularity, possibly inflammatory, and closely related to destruction involving cells other than the PMN.

Aged↗
PubMed1990

Sulfated polysaccharides prevent human leukocyte elastase-induced acute lung injury and emphysema in hamsters.

Studies were designed to explore the possibility that sulfated polysaccharides had the potential to prevent human leukocyte elastase (HLE)-induced lung injury. Arteparon (GAGPS), heparin, heparan sulfate, chondroitin sulfate, and dextran sulfate, but not dextran, inhibited HLE-mediated hydrolysis of succinyl-ala2-val-pNA. GAGPS, used as a paradigmatic sulfated polysaccharide, was a potent inhibitor of elastolysis in vitro. GAGPS given intratracheally prevented acute injury and emphysema in hamsters when administered up to 8 h before HLE insufflation. The results suggest that sulfated polysaccharides may be potent inhibitors of HLE-mediated lung injury.

Animals↗