Expression of the alpha-1-antitrypsin gene in mononuclear phagocytes of normal and alpha-1-antitrypsin-deficient individuals

Dexamethasone-mediated repression of MUC5AC gene expression in human lung epithelial cells

Glucocorticoids regulate gene expression via binding of the ligand-activated glucocorticoid receptor (GR) to glucocorticoid-responsive elements (GRE) in target gene promoters. The MUC5AC gene, which encodes the protein backbone of an abundant secreted airway mucin, has several putative GRE cis-elements in its 5' sequence. Mechanism(s) whereby glucocorticoids regulate mucin genes have not previously been described. In this study, the glucocorticoid dexamethasone (Dex) decreased MUC5AC mRNA abundance in A549 and NCI-H292 cell lines and primary differentiated normal bronchial epithelial cells by 50-80%, suggesting a common mechanism of MUC5AC gene repression in human lung epithelial cells. Kinetic analyses showed that MUC5AC mRNA was not significantly decreased until 6 h after Dex exposure, and that nuclear translocation of GR was biphasic, suggesting that Dex-mediated cis-repression of MUC5AC gene expression was a delayed response of GR translocation. Transfection analyses demonstrated that Dex transcriptionally repressed the MUC5AC promoter. Electrophoretic mobility shift assays with wild-type and mutant oligonucleotide probes showed that GR bound to two GRE cis-sites (nucleotides -930 to -912 and -369 to -351) in the MUC5AC promoter. Analyses of mutated MUC5AC promoter constructs demonstrated that NF-kappaB cis-sites were not involved in Dex-mediated repression of MUC5AC. Dex did not alter mRNA stability of MUC5AC transcripts. Taken together, the data indicate that Dex transcriptionally mediates repression of MUC5AC gene expression in human lung epithelial cells at quiescent states after binding of GR to one or more GRE cis-elements in the MUC5AC promoter.

Polymers of Z alpha1-antitrypsin co-localize with neutrophils in emphysematous alveoli and are chemotactic in vivo

The molecular mechanisms that cause emphysema are complex but most theories suggest that an excess of proteinases is a crucial requirement. This paradigm is exemplified by severe deficiency of the key anti-elastase within the lung: alpha(1)-antitrypsin. The Z mutant of alpha(1)-antitrypsin has a point mutation Glu342Lys in the hinge region of the molecule that renders it prone to intermolecular linkage and loop-sheet polymerization. Polymers of Z alpha(1)-antitrypsin aggregate within the liver leading to juvenile liver cirrhosis and the resultant plasma deficiency predisposes to premature emphysema. We show here that polymeric alpha(1)-anti-trypsin co-localizes with neutrophils in the alveoli of individuals with Z alpha(1)-antitrypsin-related emphysema. The significance of this finding is underscored by the excess of neutrophils in these individuals and the demonstration that polymers cause an influx of neutrophils when instilled into murine lungs. Polymers exert their effect directly on neutrophils rather than via inflammatory cytokines. These data provide an explanation for the accelerated tissue destruction that is characteristic of Z alpha(1)-antitrypsin-related emphysema. The transition of native Z alpha(1)-antitrypsin to polymers inactivates its anti-proteinase function, and also converts it to a proinflammatory stimulus. These findings may also explain the progression of emphysema in some individuals despite alpha(1)-antitrypsin replacement therapy.

Alpha1-antitrypsin deficiency. 4: Molecular pathophysiology

The molecular basis of alpha(1)-antitrypsin deficiency is reviewed and is shown to be due to the accumulation of mutant protein as ordered polymers within the endoplasmic reticulum of hepatocytes. The current goals are to determine the cellular response to polymeric alpha(1)-antitrypsin and to develop therapeutic strategies to block polymerisation in vivo.

Oncostatin M induced alpha1-antitrypsin (AAT) gene expression in Hep G2 cells is mediated by a 3' enhancer

alpha(1)-Antitrypsin (AAT) is the major serine proteinase inhibitor (SERPIN A1) in human plasma. Its target proteinase is neutrophil elastase and its main physiological function is protection of the lower respiratory tract from the destructive effects of neutrophil elastase during an inflammatory response. Circulating levels of AAT rise 2-3-fold during inflammation and the liver produces most of this increase. The cytokines oncostatin M (OSM) and interleukin-6 have been shown to be mainly responsible for this effect, which is mediated via the interaction of cytokine-inducible transcription factors with regulatory elements within the gene. In the present study, we report for the first time that OSM stimulation of hepatocyte AAT occurs via an interaction between the hepatocyte promoter and an OSM-responsive element at the 3'-end of the AAT gene. This effect is mediated by the transcription factor signal transducer and activator of transcription 3 ('STAT 3') binding to an OSM-responsive element (sequence TTCTCTTAA), and this site is distinct from, but close to, a previously reported interleukin-6-responsive element.

Polymers of alpha(1)-antitrypsin are chemotactic for human neutrophils: a new paradigm for the pathogenesis of emphysema

Plasma deficiency of alpha(1)-antitrypsin is most commonly due to the Z mutation ((342)Glu--> Lys) and is associated with early-onset panlobular emphysema. The lung disease in these patients is attributed to the relative deficiency of circulating alpha(1)-antitrypsin resulting in uncontrolled neutrophil-derived proteolytic activity. We have previously demonstrated that the local deficiency of Z alpha(1)-antitrypsin is exacerbated by the formation of polymers within the lung and now show that this polymerization not only inactivates alpha(1)-antitrypsin but also converts the molecule to a chemoattractant for human neutrophils. The chemotactic action of polymeric alpha(1)-antitrypsin was substantially greater than that seen with other conformers, was of similar magnitude to C5a, and was apparent over a range of physiologically relevant concentrations (EC(50) 0.0045 +/- 0.002 mg/ml). The biologic activity of polymeric alpha(1)-antitrypsin was confirmed by the demonstration that polymers, but not native alpha(1)-antitrypsin, induced neutrophil shape change and stimulated myeloperoxidase release and neutrophil adhesion. Polymeric alpha(1)-antitrypsin had no effect on basal or N-formyl-Met-Leu-Phe- stimulated superoxide anion release or constitutive apoptosis. The chemotactic properties of polymeric alpha(1)-antitrypsin may provide an explanation for the excessive neutrophils found in the lungs of Z alpha(1)-antitrypsin homozygotes and suggests a new paradigm for the pathogenesis of emphysema in these patients.

Muc-5/5ac mucin messenger RNA and protein expression is a marker of goblet cell metaplasia in murine airways

Airway inflammation, hyperreactivity, increased number of goblet cells, and mucus overproduction characterize asthma. Respiratory challenge with ovalbumin (OVA) of sensitized mice has been shown by several laboratories to cause pulmonary pathology similar to that observed in human allergic asthma. Recently, interleukin (IL)-13 has been shown to be a central mediator in this process. Because the airways of healthy mice have few, if any, mucus-producing cells, an increase in the number of these cells likely reflects induction of mucin-gene expression. The purpose of this study was to identify mucin genes induced as a result of airway goblet-cell metaplasia (GCM) in mice sensitized and challenged with OVA or in mice treated with IL-13 alone. BALB/c mice were sensitized by intraperitoneal injection (Days 0, 4, 7, 11, and 14) and intranasal instillation (Day 14) of 100 microg of OVA in saline, and then challenged by intranasal instillation (Days 25, 26, and 27) of the same. IL-13-treated mice received 5 microg of IL-13 by intranasal instillation on three consecutive days. Control mice were given saline alone. All mice were studied 24 h after the last challenge. Histologic analysis of the lungs revealed both a striking peribronchial and perivascular lymphocytic and eosinophilic inflammation and airway GCM in OVA-treated mice, and also airway GCM without inflammation in IL-13-treated mice. Northern blot analysis of lung RNA demonstrated (1) expression of Muc-5/5ac messenger RNA (mRNA) in OVA-treated and IL-13-treated mice, but not in control mice; (2) expression of Muc-1 mRNA at comparable levels in all mice regardless of treatment; and (3) no expression of Muc-2 or Muc-3 mRNA in control or treated mice. Western blot analysis demonstrated the expression of Muc-5/5ac protein (both apomucin and glycosylated mucin) in lung lysates of OVA-treated (but not control) mice, and also the expression of Muc-5/5ac mucins in the bronchoalveolar lavage fluid of OVA-treated and IL-13-treated mice. These findings demonstrate that airway GCM is associated with the induction of pulmonary expression of Muc-5/5ac mRNA and mucin in murine models of allergic asthma.

Modulation of elastase binding to elastin by human alveolar macrophage-derived lipids

Human neutrophil elastase (HNE), an enzyme secreted by activated neutrophils, can bind to and degrade extracellular matrix including human lung elastin. This protease is believed to play an important role in several destructive processes including pulmonary emphysema. In this study, we hypothesized that an alveolar macrophage (AM) product or products may interact with neutrophil elastase (NE) and modulate its binding to elastin. Elastase binding to elastase was evaluated by a modified elastase functional assay using a synthetic substrate. Supernatants from cultured AM inhibited elastase binding to elastin at a dose-dependent manner without inhibiting functional elastase activity. The AM products had a heterogeneous molecular weight ranging from 440,000 to 54,000. The activity was heat-stable, but was lost after ultracentrifugation. After lipid fractionation, neither the aqueous nor the lipid fractions contained activity, suggesting that the factor may be a lipid complex. Culture supernatants from smokers' AM released significantly higher amounts of the factor than nonsmokers. In addition, high-molecular-weight elastase was present in bronchoalveolar lavage fluid (BALF) obtained from patients with pneumonia. Most of the in vivo high-molecular-weight elastase was lost after lipid extraction. In conclusion, macrophages release a factor or factors, probably lipid, which can interact with NE and inhibit its binding to human lung elastin without inhibiting elastase activity. This macrophage-derived factor may play a role in protecting the lung from NE by partitioning elastase into the airspace and thus protecting the interstitial connective tissue matrix from elastase degradation.

alpha1-antitrypsin genotypes and the acute-phase response to open heart surgery

A mutation in the 3' region of the alpha1-antitrypsin (alpha1-AT) gene is associated with chronic obstructive pulmonary disease (COPD). However, the reason for this association is unknown. The mutation does not cause alpha1-AT deficiency but in vitro studies suggest it could attenuate the rise in alpha1-AT levels during the acute-phase response. Therefore, we sought an association between the 3' mutation and a reduced rise in alpha1-AT levels following open heart surgery, a known trigger of the acute-phase response. We genotyped 198 patients and identified 31 with the 3' mutation. Their alpha1-AT rise was compared with the remaining 167 wild type subjects. Multiple linear regression analysis identified sex, urgency of surgery, and surgical pump time as significant independent predictors of the rise in alpha1-AT. However, we found no association between the 3' mutation and a reduced rise in alpha1-AT. We also identified patients who had the Z and S alpha1-AT deficiency mutations and found a significant reduction in the rise in alpha1-AT in individuals who were heterozygous for the Z mutation compared with wild type subjects. However, when the rise in alpha1-AT was expressed as a percentage of the basal level, there was no significant difference between individuals who had the S or Z mutations compared with wild type. Therefore, an attenuated alpha1-AT acute-phase response does not explain previous associations of the 3' and S mutations with COPD. However, a deficient acute-phase rise in alpha1-AT may contribute to the susceptibility to COPD associated with the Z mutation.

Respiratory carcinoma cell lines. MUC genes and glycoconjugates

Lung carcinoma cell lines are being used in many laboratories to study various airway epithelial functions, including mucin gene expression. To identify model systems for investigating regulation of MUC5/5AC gene expression and secretion of MUC5/5AC mucins in airway epithelial cells, we evaluated the expression of several mucin genes in six carcinoma cell lines of respiratory tract origin. RNA was extracted from A549, Calu-3, NCI H292, Calu-6, RPMI 2650, and A-427 cells; MUC1, MUC2, MUC4, MUC5/5AC, and MUC5B messenger RNA (mRNA) expression was determined. By Northern analyses, all cell lines expressed MUC1 mRNA, whereas MUC2 mRNA was not detectable in any of the cell lines. RPMI 2650 cell lines expressed only MUC1 mRNA. NCI-H292 cells expressed MUC4 and low levels of MUC5/5AC mRNA. Calu-3 and A549 cells expressed MUC5/5AC mRNA; A549 cells also expressed MUC5B mRNA. Glycoconjugates secreted by lung carcinoma cells were also examined. By wheat germ lectin analysis, Calu-3, H292, and A549 cells secreted high molecular weight glycoproteins having N-acetylglucosamine and/or sialic acid moieties. Western blot analyses with an anti-MUC5:TR-3A antibody demonstrated that Calu-3 and A549 cells secreted MUC5/5AC mucins. All six carcinoma cell lines secreted large, radiolabeled, sulfated macromolecules; the majority were proteoglycans that were digested by hyaluronidase. However, Calu-3 cells also secreted sulfated high molecular-weight glycoproteins that were immunoprecipitated by anti-MUC5:TR-3A antibody. These studies demonstrated that Calu-3 and A549 cell lines expressed high and moderate amounts of MUC5/5AC mRNA and MUC5/5AC mucins, whereas H292 cells expressed lesser amounts. These cell lines should prove useful for studies of MUC5/5AC gene expression and MUC5/5AC biosynthesis, trafficking, and secretions in airway epithelial cells.

Local control of alpha1-proteinase inhibitor levels: regulation of alpha1-proteinase inhibitor in the human cornea by growth factors and cytokines

Alpha 1-proteinase inhibitor is a major serine proteinase inhibitor in the human cornea involved in the protection of the avascular corneal tissue against proteolytic damage. This inhibitor is upregulated systemically during infection, inflammation and injury. Cytokines that mediate the acute phase response such as IL-1beta and IL-2 increased alpha1-proteinase inhibitor present in corneal organ culture media. This released inhibitor represented mainly newly synthesized protein. However, IL-6, a general inducer of the acute phase response that upregulates alpha1-proteinase inhibitor in all other tissues and cells tested, failed to alter corneal alpha1-proteinase inhibitor levels over the tested period of 24 h. In addition to IL-1beta and IL-2, alpha1-proteinase inhibitor levels in the corneal organ culture medium increased following the addition of FGF-2 and IGF-I. The effect of the above growth factors and cytokines was relatively fast with maximal induction observed within the first 5 h. Among the tested growth factors and cytokines, IL-1beta was the most potent and increased total corneal alpha1-proteinase inhibitor levels approximately 2.4-fold in the cornea organ culture medium. Newly, synthesized alpha1-proteinase secreted into the medium increased 3.9-fold. In addition to the effect on corneal alpha1-proteinase inhibitor, IL-1beta also increased the amount of alpha1-proteinase inhibitor released by monocytes and macrophages but not by HepG2, CaCo2, and MCF-7 cells within 24 h. These results suggest that the cornea can locally control levels of alpha1-proteinase inhibitor in response to an inflammatory insult.

Oncostatin M is a potent stimulator of alpha1-antitrypsin secretion in lung epithelial cells: modulation by transforming growth factor-beta and interferon-gamma

alpha1-Antitrypsin (alpha1-AT) plays a key role in lung homeostasis. Although the hepatocyte is considered as the primary source of alpha1-AT, we have previously demonstrated that rat alveolar epithelial type II cells as well as the human A549 cell line synthesize alpha1-AT, suggesting its local production within the lung. In the present study, we showed that oncostatin M, as opposed to interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), or IL-6, is a potent stimulator of alpha1-AT synthesis in the human A549 cell line. The oncostatin M-induced alpha1-AT secretion is modulated by interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) at both the protein and mRNA levels. IFN-gamma decreases oncostatin M-induced alpha1-AT secretion. By contrast, TGF-beta in combination with oncostatin M induces a dramatic and synergistic upregulation that is not observed in the HepG2 hepatocyte cell line. Our results suggest that during an inflammatory process, alveolar epithelial cells may contribute to the antiprotease defense within the lung.

Alpha 1-antitrypsin and protease complexation is induced by lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha in monocytes

Local regulation of alpha1-antitrypsin (alpha1-AT) may have importance in maintenance of the protease-antiprotease balance in the microenvironment of inflammatory cells. We therefore studied whether lipopolysaccharide (LPS), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNFalpha) affect the pericellular concentration of alpha1-AT in human peripheral blood mononuclear cells (PBMC). PBMC taken from normal healthy volunteers were treated with LPS, IL-1beta, and TNFalpha, and the concentration of human alpha1-AT in conditioned supernatants was measured. When compared with unstimulated control supernatants (147 +/- 19 ng/ml), LPS (439 +/- 66 ng/ml; p < or = 0.001), IL-1beta (263 +/- 37 ng/ml; p < or = 0.01), and TNFalpha (316 +/- 59 ng/ml; p < or = 0.05) induced a 2- to 3-fold increase of alpha1-AT. Up-regulation of alpha1-AT protein correlated with an increase in alpha1-AT mRNA, suggesting a simultaneous increase in alpha1-AT synthesis. Despite the increase in alpha1-AT concentration, functional antiprotease activity could not be detected. Furthermore, protease activity was present in all samples, with the amount of activity being inversely related to the amount of alpha1-AT measured in supernatants. These findings suggest that local inflammatory conditions up-regulate alpha1-AT production by monocytes which complex with a protease derived from the PBMC population.

Regulation of the serine proteinase inhibitor (SERPIN) gene alpha 1-antitrypsin: a paradigm for other SERPINs

alpha 1-antitrypsin (AAT) is the archetypal member of the serine proteinase inhibitor (SERPIN) gene family. AAT is an acute-phase reactant and the plasma concentration increases three- to four-fold during the inflammatory response. In hepatocytes this increase is mediated primarily by the cytokine interleukin-6 (IL-6) via the transcription factor NF-IL6. The AAT gene contains at least two enhancer elements, one at the 5' end of the gene and the other at the 3' end. Functional studies performed in mammalian hepatoma cells (Hep G2) using constructs containing these AAT enhancer regions linked to a reporter gene have demonstrated that the 5' enhancer is dominant under basal conditions and that, following stimulation with IL-6, both enhancers are essential and the 3' enhancer plays a major role. We have identified a mutation associated with lung disease which occurs in the 3' AAT enhancer; the mutation occurs at a binding site for the ubiquitous transcription factor Oct-1. The functional significance of this mutation is a deficient IL-6 response. Using the AAT gene as a model, we describe the interactions which occur between transcription factors within the 3' enhancer and also those which take place between the 5' and 3' enhancers. These studies shed light on the molecular mechanism of the acute-phase response which could possibly be extended to other members of the SERPIN gene family.

Unidirectional upregulation of the synthesis of the major iron proteins, transferrin-receptor and ferritin, in HepG2 cells by the acute-phase protein alpha1-antitrypsin

BACKGROUND/AIMS

We have previously shown that the hepatic acute-phase protein alpha1-antitrypsin (alpha1-AT) is an important mediator of changes in iron metabolism in the course of anaemia of chronic disease. Alpha1-AT profoundly reduces growth of erythroid cells by interfering with transferrin-mediated iron uptake. In the present work we investigate the effects of alpha1-AT on hepatic iron metabolism, as the liver plays a central role in body iron metabolism and in metabolic changes during acute-phase response.

METHODS

The human hepatoma cell line Hep G2 was cultured in RPMI 1640+10% FCS. The effect of alpha1-AT on transferrin-receptor binding was investigated in equilibrium binding assays with 125I-transferrin. Expression of transferrin receptor was determined by saturation experiments and intracellular ferritin was measured in cell lysates after incubating cells either alone or with alpha1-AT. To determine iron regulatory protein binding activity to iron responsive elements we used gel retardation assays and Northern blot analysis was carried out to investigate transferrin receptor and ferritin mRNA expression.

RESULTS

Alpha1-AT completely prevented transferrin from binding to its receptor and internalization of the transferrin-transferrin receptor complex on HepG2. In addition, alpha1-AT caused a distinct increase in iron regulatory protein binding activity to iron responsive elements, which is characteristic of iron deprivation. Normally, the synthesis of transferrin receptor and ferritin is regulated bidirectionally, but alpha1-AT promoted a unidirectional regulation. Alpha1-AT increased the synthesis of both transferrin receptor and ferritin and, moreover, increased cellular amounts of transferrin receptor mRNA and ferritin H-chain mRNA.

CONCLUSIONS

The effect of alpha1-AT on transferrin receptor synthesis appears to be mediated via activation of iron responsive element binding affinity of iron regulatory protein leading to an increased stability of transferrin receptor mRNA. Changes in ferritin, however, may be related to a transcriptionally mediated, iron-independent pathway which overrides the influence of activated iron regulatory protein. These specific changes in iron metabolism are the very ones seen in the course of anaemia of chronic disease. Our results emphasize the central role of alpha1-AT as a mediator of altered iron metabolism, characteristic of anaemia of chronic disease, not only with respect to erythroid cells but also with respect to liver cells.

Low density lipoprotein catabolism is enhanced by the cleaved form of alpha-1-antitrypsin

The frequent occurrence of hypocholesterolaemia following inflammatory processes is well known but unexplained. Elevated plasma levels of serine proteinase inhibitors (serpins) and their complexes with target enzymes have been demonstrated in inflammatory, malignant and infectious diseases which are also often accompanied by low plasma cholesterol levels. Under inflammatory conditions, uncomplexed, but cleaved inactive serpins arising from slow deacylation of the serpin-proteinase complex may be present in the circulation. To determine the influence of native and cleaved forms of serpins, such as alpha-1-antitrypsin (AAT), on lipoprotein metabolism, we investigated the effect of these forms on low density lipoprotein (LDL) catabolism in human HepG2 cell line. We have found that the cleaved form of AAT in concentrations from 125 to 2000 nmol l-1 stimulates LDL binding to the HepG2 cells, by up to 49% with a subsequent increase in LDL uptake and degradation of up to 79 and 65% respectively. Native AAT was also found to increase LDL binding and internalization by 20-25%, independently of the amount of AAT added, an effect most probably due to the cleaved form of AAT produced by local proteolysis of native AAT incubated in the cell culture. Moreover we have shown that the cleaved form of AAT interacts with LDL in vitro, and that such an interaction abolishes AAT ability to stimulate LDL binding and internalization. This study for the first time describes the ability of the cleaved form of AAT to stimulate LDL binding and internalization in HepG2 cell culture, and provides evidence that hypocholesterolaemia occurring during inflammatory processes may be mediated by cleaved forms of serpins.

Review: alpha 1-antitrypsin deficiency associated liver disease

alpha 1-Antitrypsin (alpha 1-AT) deficiency is the most common genetic cause of liver disease in children and genetic disease for which children undergo liver transplantation. It also causes cirrhosis and hepatocellular carcinoma in adults. Studies by Sveger in Sweden have shown that only a subgroup of the population with homozygous PiZZ alpha 1-AT deficiency develop clinically significant liver injury. Other studies have shown that the mutant alpha 1-AT Z molecule undergoes polymerization in the endoplasmic reticulum and that a subpopulation of alpha 1-AT-deficient individuals may be susceptible to liver injury because they also have a trait that reduces the efficiency by which the mutant alpha 1-AT Z molecule is degraded in the endoplasmic reticulum.

Baseline characteristics of enrollees in the National Heart, Lung and Blood Institute Registry of alpha 1-antitrypsin deficiency. Alpha 1-Antitrypsin Deficiency Registry Study Group

OBJECTIVE

alpha 1-Antitrypsin (alpha 1-AT) deficiency is a hereditary disorder characterized by a high risk for the development of emphysema at an early age. In 1988, the National Heart, Lung and Blood Institute, National Institutes of Health, initiated a registry of individuals with alpha 1-AT deficiency to help define the natural history and clinical course of this disorder. This article describes demographic and clinical characteristics of subjects enrolled in the Registry at baseline.

DESIGN

Prospective longitudinal natural history study.

SETTING

Thirty-seven clinical centers in the United States (36 centers) and Canada (one center).

PATIENTS

There were 1,129 subjects 18 years of age or older with severe deficiency of alpha 1-AT, defined as having serum alpha 1-AT levels < or = 11 mumol/L confirmed by a Central Phenotyping Laboratory, or a ZZ or ZNull genotype identified by genomic DNA analysis.

RESULTS

Most enrollees were symptomatic white subjects in their fourth to sixth decade, with a ZZ phenotype, a history of having smoked cigarettes, and pulmonary function tests demonstrating a pattern consistent with emphysema. Interestingly, only a small percentage were current smokers on enrollment, suggesting that this population is amenable to smoking cessation. A subgroup of individuals in the Registry with relatively normal lung function were younger, more likely to have never smoked and more likely to have come to medical attention owing to a family history of alpha 1-AT deficiency rather than symptomatic involvement.

CONCLUSIONS

These results emphasize the need for increased awareness and early detection of alpha 1-AT deficiency. In this endeavor, dissemination of the information contained in the Registry to health-care professionals and the general population, along with initiation of appropriate preventative measures before significant lung damage has occurred, could have considerable benefits for individuals with this condition.

alpha 1-Proteinase inhibitor in gingival crevicular fluid of humans with adult periodontitis: serpinolytic inhibition by doxycycline

The serum protein, alpha 1-proteinase inhibitor (alpha 1-PI), defends the host against serine proteinases, e.g. PMN elastase. Using a rabbit anti-serum against human alpha 1-PI, this protein in GCF was quantified from a standard curve constructed from dot-blot analysis and characterized by Western blot. GCF was collected on filter paper strips from healthy (H), gingivitis (G) and adult periodontitis (AP) patients, then extracted with Tris/NaCl/CaCl2 buffer, pH 7.6. alpha 1-PI concentration increased with G and was highest in AP subjects. H sites only showed intact alpha 1-PI (52 kDa); no degradation fragments (48 kDa) were detected. In G and AP subjects, alpha 1-PI degradation fragments were seen in 17% and 71% of GCF samples, respectively. Both collagenase and alpha 1-PI-degrading activities in GCF increased with severity of inflammation (GCF flow). Moreover, the alpha 1-PI degrading (or serpinolytic) activity was characterized as a matrix metalloproteinase, probably collagenase, based on its in vitro response to a panel of different proteinase inhibitors including doxycycline. We propose: (1) that collagenase promotes periodontal breakdown not only by degrading collagen, but also by depleting alpha 1-PI regulation of elastase and other serine-proteinases, thereby favoring a broader attack on extracellular matrix (ECM) constituents, and (2) based on a recent longitudinal double-blind study using the techniques described above for alpha 1-PI analysis, that low-dose doxycycline administration to humans with adult periodontitis can inhibit this broad cascade of ECM degradation.

Endothelial cell associated anti-elastolytic activity

Addition of cultured and then carefully-washed bovine pulmonary artery endothelial cells (EC) decreased (p < 0.05) human neutrophil elastase activity (HNE) in vitro. HNE activity was also decreased (p < 0.05) by addition of histone or protamine treated EC. However, addition of papain or trypsin treated EC decreased HNE activity less than addition of untreated cells suggesting that a protein rather than a difference in cell surface charge was responsible. Other observations suggest that EC anti-elastolytic activity was not due to binding of antiprotease from culture media but was dependent on EC protein synthesis. First, addition of EC grown previously in serum-free media decreased HNE activity the same (p < 0.05) as addition of EC cultured in media containing serum. Second, addition of EC treated beforehand with cycloheximide decreased HNE activity less than (p < 0.05) addition of untreated control EC. We conclude that EC most likely make and have anti-elastolytic activity on their surfaces and speculate that EC associated anti-elastolytic activity may modulate inflammatory, repair and other biologic processes involving neutrophil elastase.

Visna-maedi virus-induced expression of interleukin-8 gene in sheep alveolar cells following experimental in vitro and in vivo infection

Visna-maedi virus is a lentivirus which causes inflammatory disorders in sheep, including a chronic interstitial lung disease resembling that observed in human immunodeficiency virus type 1 (HIV 1) infection. In view of our previous demonstration of the production of neutrophil chemotactic activity by alveolar macrophages, and given the lymphocytic and neutrophilic nature of the alveolar cell infiltrate in both naturally and experimentally infected animals, we hypothesized that interleukin-8 (IL8) could be a candidate for at least part of the chemotactic activity we described. In this study, we investigated IL8 mRNA expression following visna-maedi virus infection. Northern analysis of total RNA using an ovine IL8-specific probe demonstrated that the IL8 gene is upregulated in alveolar macrophages as a consequence of in vitro infection and in alveolar cells from experimentally infected animals. Using a semi-quantitative RT-PCR method, we showed that various levels of IL8 mRNA are expressed by alveolar cells from infected animals and that they correlate with the intensity of the lesions. In conclusion, visna-maedi virus is able to induce IL8 mRNA expression in sheep alveolar cells. Results from in vivo infected animals suggest that IL8 could play a role in the early build-up of visna-maedi virus-induced lesions.

Inhalation toxicity of diborane in rats assessed by bronchoalveolar lavage examination

Changes in bronchoalveolar lavage fluid (BALF) and blood were examined to assess the toxic effects of diborane (B2H6, CAS: 19287-45-7) on the lung. Male Wistar rats were exposed to diborane at 20 ppm (intended concentration) for 4 h (phase I study) to evaluate time-course changes up to 14 days, and at 10 or 1 ppm (intended concentrations) to assess the dose-effect relationship after 3 days (phase II study). BALF parameters [leukocyte counts, alpha 1-antitrypsin (alpha 1-AT), superoxide dismutase (SOD), total protein, phospholipids etc.] were examined and biochemical and histopathological studies were also carried out. In the phase I study, neutrophils (%) in BALF increased on the day of exposure and then decreased gradually for 3 days. Rapid and marked increases in alpha 1-AT and SOD activity in BALF were detected on the day of exposure, and phospholipids had sharply increased on day 3. After 14 days, these parameters in the exposed rats had returned to their background level and alpha 1-AT decreased significantly. In the phase II study, total protein, alpha 1-AT activity and phospholipids in BALF showed dose-dependent increases, and serum alpha 1-AT activity increased significantly. Alveolar capillary and alveolar cell damage were confirmed in rats exposed to 20 ppm, 10 ppm or 1 ppm diborane for 4 h by evaluating the parameters examined. The protection system appeared to start operating immediately after exposure, and the recovery mechanism seemed to start operating 1 day after exposure and cease by day 14. The no-observed-effect level could not be observed.

Differences in distribution and synthesis of the functional opponents alpha 1-proteinase inhibitor and neutrophil elastase in eukaryotic cells

Alpha 1-proteinase inhibitor (alpha 1-Pi) is the main physiological inhibitor of neutrophil elastase, a serine protease that has been implicated in tissue degradation at inflammatory sites. We report here on an immunocytochemical study of various eukaryotic cells in order to show their content of alpha 1-Pi. The proteinase inhibitor is present in undifferentiated and differentiated HL-60 and U937 cells, in myeloblasts and neutrophils, and also in tissues such as liver, kidney, colon and eye where local inflammatory processes can take place. Labelling of HL-60, U937, neutrophils and HepG2 cells with [35S] methionine followed by immunoprecipitation of cell homogenates with an anti-alpha 1-Pi antibody revealed that these cells can synthesize alpha 1-Pi de novo, and secrete large amounts of the newly synthesized molecule into the medium. In contrast, neutrophil elastase is only present in white blood cells of myeloid and monocytic lineage but not in other tissues investigated which contain alpha 1-Pi. The results demonstrate the possibility of ubiquitous local synthesis of alpha 1-Pi ready to inhibit the elastase which is imported into the affected tissues during inflammatory processes by circulating cells of the haematopoietic system.

Differential recognition of alpha 1-antitrypsin-elastase and alpha 1-antichymotrypsin-cathepsin G complexes by the low density lipoprotein receptor-related protein

Two multifunctional receptors, low density lipoprotein receptor-related protein (LRP) and gp330, have been implicated in the cellular uptake and degradation of a wide spectrum of functionally diverse ligands including plasma lipoproteins, proteases, and proteinase-inhibitor complexes. The two receptors show distinct tissue-specific expression patterns, suggesting different physiological functions. We have examined the cellular degradation of two serine proteinase inhibitor (serpin)-protease complexes, alpha 1-antitrypsin-neutrophil elastase (alpha 1AT.NEL) and alpha 1-antichymotrypsin-cathepsin G (alpha 1ACT.CathG) by normal murine fibroblasts (MEF) expressing LRP, and by a mutant fibroblast cell line (PEA13) which is genetically deficient for LRP. alpha 1AT.NEL complexes bound to LRP on ligand blots and were degraded efficiently by the MEF cells, but not by PEA13 cells. Degradation of the complexes was also significantly reduced by antibodies directed against LRP, further suggesting that fibroblasts require LRP for the cellular uptake and degradation of alpha 1AT.NEL complexes. In contrast to alpha 1AT.NEL, MEF cells did not degrade alpha 1ACT.CathG complexes. However, these complexes were rapidly degraded by the rat embryonal carcinoma cell line L2p58 which abundantly expresses gp330, raising the possibility that the alpha 1ACT.CathG complex might be recognized by gp330. Both complexes were efficiently metabolized by the hepatoma cell line HepG2, presumably involving the serpin-enzyme complex receptor. The differential recognition of serpin-protease complexes by fibroblasts and hepatoma cells, however, indicates that LRP, gp330, and the serpin-enzyme complex receptor are distinct proteins.

Increasing expression of the normal human CFTR cDNA in cystic fibrosis epithelial cells results in a progressive increase in the level of CFTR protein expression, but a limit on the level of cAMP-stimulated chloride secretion

Cystic fibrosis (CF) results from mutations of the CF transmembrane conductance regulator (CFTR) gene and the consequent defective regulation of cAMP-stimulated Cl- permeability across epithelial cell apical membranes. Given that in vitro transfer of normal CFTR cDNA corrects this defect and that recombinant adenovirus (Ad) vectors can transfer the normal human CFTR cDNA in vivo, Ad vectors have significant potential in the development of effective strategies for CF gene therapy. One concern is whether CFTR overexpression achievable with Ad vectors may have untoward effects on cAMP-stimulated Cl- efflux. To address this, the CF pancreatic epithelial cell line CFPAC-1 was infected with increasing doses of AdCFTR, a recombinant Ad containing the normal CFTR cDNA, and analyzed for CFTR mRNA and protein levels and CFTR function. As the AdCFTR dose increased [multiplicity of infection (moi) 0-1,000], CFTR mRNA and protein levels increased. However, while CFTR function measured by cAMP-stimulated 36Cl- efflux was observed with low doses of the vector (moi 20), there was no further increase in CFTR function with increasing doses of AdCFTR (moi from 20 to 1,000). These data suggest that after AdCFTR-mediated gene transfer, epithelial cells limit the level of cAMP-stimulated Cl- secretion despite increasing levels of CFTR protein.

Increased expression of tissue factor mRNA and procoagulant activity in ovine lentivirus-infected alveolar macrophages

To link ovine lentivirus infection to lung tissue damage, we studied the procoagulant response in alveolar macrophages from experimentally infected lambs and in in vitro infected alveolar macrophages. We cloned ovine tissue factor cDNA and analysed its in vitro expression by Northern blotting. Visna-maedi virus induced tissue factor mRNA. In order to correlate this mRNA induction with its cellular function, we analysed macrophage procoagulant activity after in vitro and in vivo infection. The procoagulant activity was increased by interaction with the virus in both cases. Thus, visna-maedi virus-induced expression of tissue factor mRNA was associated with enhanced macrophage procoagulant activity. These findings indicate an active role of alveolar macrophages in the pathogenesis of these inflammatory lung lesions.

Gene transfer to freshly isolated human respiratory epithelial cells in vitro using a replication-deficient adenovirus containing the human cystic fibrosis transmembrane conductance regulator cDNA

Cystic fibrosis (CF) results from mutations of the CF transmembrane conductance regulator (CFTR) gene and subsequent defective regulation of cAMP-stimulated chloride (Cl-) permeability across the apical membrane of epithelial cells. In vitro transfer of normal CFTR cDNA corrects this defect, and studies in experimental animals have shown successful gene transfer to airway epithelium in vivo using a recombinant adenoviral vector containing the human CFTR cDNA (AdCFTR), supporting the feasibility of in vivo AdCFTR-mediated gene therapy for the respiratory manifestations of CF. One step in applying this therapy to CF patients is to evaluate the safety and efficacy of AdCFTR-mediated gene transfer in the actual target for human gene therapy, human airway epithelium. The present study demonstrates that AdCFTR restores cAMP-stimulated Cl- permeability in human CF bronchial epithelial cells. In addition, the study utilizes freshly isolated human airway epithelial cells from the nose and/or bronchi of normal individuals and/or individuals with CF to demonstrate that after in vitro AdCFTR-mediated gene transfer: (i) AdCFTR DNA does not replicate as a function of dose and time; (ii) CF epithelial cells express AdCFTR-mediated normal human CFTR mRNA; and (iii) CF epithelial cells, including terminally differentiated ciliated cells (the most common airway epithelial cell type), express the normal human CFTR protein. Together, these data support the use of AdCFTR in human gene therapy trials and suggest that biologic efficacy should be achievable in vivo.

Changes of immunoreactivity in alpha 1-antitrypsin in patients with autoimmune diseases

Recent studies from this laboratory have shown that a monoclonal antibody prepared against a specific epitope on alpha 1-antitrypsin is a valuable diagnostic marker for autoimmune conditions. In the present study we have further characterized this monoclonal antibody and reassessed its diagnostic value in screening samples from patients with various autoimmune conditions. alpha 1-Antitrypsin was micropurified from patients with selected autoimmune conditions and from normal donors. The purified alpha 1-antitrypsin isolated from patients with autoimmune conditions and normal donors was deglycosylated using both a mixture of exoglycosidases and endoglycosidase F. The immunoreactivity of the native and deglycosylated alpha 1-antitrypsin was examined using both a monoclonal antibody and a polyclonal antibody in enzyme linked immunosorbent assay (ELISA) and radioimmunoassay (RIA), respectively. It was noted that alpha 1-antitrypsin isolated from patients with autoimmune diseases generated a displacement curve dissimilar to alpha 1-antitrypsin purified from normal donors or alpha 1-antitrypsin from patients with autoimmune diseases subjected to deglycosylation when these samples were examined by ELISA using the monoclonal antibody. However, when the polyclonal antibody was used for these studies, no difference was found between the native and deglycosylated alpha 1-antitrypsin suggesting that the monoclonal antibody recognized an epitope not detectable by the polyclonal antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-1 antitrypsin gene exon use in stimulated lymphocytes

AIMS

To investigate the expression of mRNA transcripts containing exon A or B in lymphocyte cultures.

METHODS

An in situ hybridisation technique, using synthetic, biotinylated oligonucleotide probes was deployed to allow the demonstration of exon A, exon B, or the normal hepatocyte message containing exon C.

RESULTS

Lymphocytes used the same alternative splicing technique as monocytes in the generation of their alpha-1 antitrypsin message. They also provided data on the frequency of exon A and B expression in cells from different subjects. Most circulating granulocytes failed to show the alpha-1 antitrypsin message, suggesting that this protein is synthesised in the marrow and represents a stored protein component in polymorph and circulating nuclear lymphocytes.

CONCLUSIONS

In situ hybridisation is a sensitive technique for the detection of individual gene exon use in cell populations. Lymphocytes show the same promoter use as that described for monocytes.

Alpha-1 antitrypsin response of stimulated alveolar macrophages

Alpha-1 antitrypsin messenger RNA (A1AT mRNA) was determined in alveolar macrophages and in peripheral blood monocytes of healthy individuals using a sensitive RNase protection assay. Determinations were made of bacterial lipopolysaccharide (LPS) stimulated and unstimulated cells. We found that the amount of A1AT mRNA increased 7.3 and 14 times after 4 h of incubation with LPS for monocytes and macrophages, respectively (relative to total RNA). The increase was 12.3 and 14.8 times, respectively, when expressed as increase per cell. In both cell types there was wide interindividual variation in LPS response: 2-36 and 5-12 times for monocytes and macrophages, respectively. The possible significance of A1AT production of monocytes and macrophages may be the local control of granulocytic proteases such as elastase and cathepsin G.

Constitutive and modulated expression of the human alpha 1 antitrypsin gene. Different transcriptional initiation sites used in three different cell types

alpha 1-Antitrypsin (alpha 1 AT) is plasma glycoprotein that constitutes the principle inhibitor of neutrophil elastase in tissue fluids. It has been considered a prototype for liver-derived acute phase proteins in that its concentration in plasma increases three- to fourfold during the host response to inflammation/tissue injury. However, recent studies have shown that alpha 1 AT is expressed in several types of extrahepatic cells, including mononuclear phagocytes and enterocytes, and that there are distinct transcriptional units used in hepatocytes and at least one extra-hepatic cell type, blood monocytes. In this study, we have used a combination of ribonuclease protection assays, primer elongation analysis, and transcriptional run-on assays to further characterize mechanisms of basal and modulated alpha 1 AT gene expression in hepatocytes, enterocytes, and macrophages. The hepatoma cell line HepG2, intestinal epithelial cell line Caco2, and primary cultures of human peripheral blood monocytes were used as examples of the cell types. The results indicate that there are three macrophage-specific transcriptional initiation sites upstream from a single hepatocyte-specific transcriptional initiation site. Macrophages use these sites during basal and modulated expression. Hepatoma cells use the hepatocyte-specific transcriptional initiation site during basal and modulated expression but also switch on transcription from the upstream macrophage transcriptional initiation sites during modulation by the acute phase mediator interleukin 6 (IL-6). Caco2 cells use the hepatocyte-specific transcriptional initiation site during basal expression. There is a marked increase in the use of this site and an increase in the rate of transcriptional elongation of alpha 1 AT mRNA during differentiation of Caco2 cells from crypt-type to villous-type enterocytes. Caco2 cells also switch on transcription from the upstream macrophage transcriptional initiation sites during modulation by IL-6. These results provide further evidence that there are differences in the mechanisms of constitutive and regulated expression of the alpha 1 AT gene in at least three different cell types, HepG2-derived hepatocytes, Caco2-derived enterocytes and mononuclear phagocytes.

In vivo transfer of the human cystic fibrosis transmembrane conductance regulator gene to the airway epithelium

Direct transfer of the normal cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene to airway epithelium was evaluated using a replication-deficient recombinant adenovirus (Ad) vector containing normal human CFTR cDNA (Ad-CFTR). In vitro Ad-CFTR-infected CFPAC-1 CF epithelial cells expressed human CFTR mRNA and protein and demonstrated correction of defective cAMP-mediated Cl- permeability. Two days after in vivo intratracheal introduction of Ad-CFTR in cotton rats, in situ analysis demonstrated human CFTR gene expression in lung epithelium. PCR amplification of reverse transcribed lung RNA demonstrated human CFTR transcripts derived from Ad-CFTR, and Northern analysis of lung RNA revealed human CFTR transcripts for up to 6 weeks. Human CFTR protein was detected in epithelial cells using anti-human CFTR antibody 11-14 days after infection. While the safety and effectiveness remain to be demonstrated, these observations suggest the feasibility of in vivo CFTR gene transfer as therapy for the pulmonary manifestations of CF.

Expression of the secretory leukoprotease inhibitor gene in epithelial cells

The secretory leukoprotease inhibitor (SLPI) gene codes for a 12-kD protein that within the lung protects the airway epithelium from neutrophil elastase. Screening of 228 alleles in 114 individuals for sequence differences by RNase protection of genomic DNA revealed no detectable polymorphisms in SLPI gene exons II-IV. SLPI gene expression in the lung was demonstrated by identifying SLPI mRNA transcripts in bronchial epithelial cells freshly isolated from normals. Cell lines derived from mucosal surfaces (HS-24 bronchial squamous cell carcinoma, HeLa cervical carcinoma) actively transcribe the SLPI gene and contain SLPI mRNA transcripts, while lung fibroblasts demonstrate no evidence of SLPI gene expression. SLPI mRNA transcripts appear to be relatively stable, with mRNA levels only mildly affected by inhibition of RNA synthesis. Chromatin DNA of HS-24 cells demonstrates two DNase I hypersensitivity sites within the 5' flanking region of exon I of the SLPI gene, whereas fibroblast chromatin has no DNase I accessible sites in the same region. Further analysis of the 5' flanking region demonstrated two contiguous transcription start sites, CAAT and TATA boxes, and several potential regions of known DNA binding proteins. Overall, the SLPI gene appears to be a relatively nonpolymorphic, stable gene that is constitutively expressed at specific tissue sites, but has the potential to be modulated at both the transcriptional and posttranscriptional levels.

Adenovirus-mediated transfer of a recombinant alpha 1-antitrypsin gene to the lung epithelium in vivo

The respiratory epithelium is a potential site for somatic gene therapy for the common hereditary disorders alpha 1-antitrypsin (alpha 1AT) deficiency and cystic fibrosis. A replication-deficient adenoviral vector (Ad-alpha 1AT) containing an adenovirus major late promoter and a recombinant human alpha 1AT gene was used to infect epithelial cells of the cotton rat respiratory tract in vitro and in vivo. Freshly isolated tracheobronchial epithelial cells infected with Ad-alpha 1AT contained human alpha 1AT messenger RNA transcripts and synthesized and secreted human alpha 1AT. After in vivo intratracheal administration of Ad-alpha 1AT to these rats, human alpha 1AT messenger RNA was observed in the respiratory epithelium, human alpha 1AT was synthesized and secreted by lung tissue, and human alpha 1AT was detected in the epithelial lining fluid for at least 1 week.

Risk factors for emphysema. Cigarette smoking is associated with a reduction in the association rate constant of lung alpha 1-antitrypsin for neutrophil elastase

The increased risk of developing emphysema among individuals who smoke cigarettes and who have normal levels of alpha 1-antitrypsin (alpha 1AT) is hypothesized to result from a decrease in the antineutrophil elastase capacity of the lower respiratory tract alpha 1AT of smokers compared with nonsmokers. To evaluate this hypothesis we compared the time-dependent kinetics of the inhibition of neutrophil elastase by lung alpha 1AT from healthy, young cigarette smokers (n = 8) and nonsmokers (n = 12). alpha 1-antitrypsin was purified from lavage fluid using affinity and molecular sieve chromatography, and the association rate constant (k assoc) for neutrophil elastase quantified. The k assoc of smoker plasma alpha 1AT (9.5 +/- 0.5 X 10(6) M-1s-1) was similar to that of nonsmoker plasma (9.3 +/- 0.7 X 10(6) M-1s-1, P greater than 0.5). In marked contrast, the k assoc of smoker lower respiratory tract alpha 1AT was significantly lower than that of nonsmoker alpha 1AT (6.5 +/- 0.4 X 10(6) M-1s-1 vs. 8.1 +/- 0.5 X 10(6) M-1s-1, P less than 0.01). Furthermore, the smoker lower respiratory tract alpha 1AT k assoc was significantly less than that of autologous plasma (P less than 0.01). When considered in the context of the concentration of alpha 1AT in the lower respiratory tract epithelial lining fluid, the inhibition time for neutrophil elastase of smoker lung alpha 1AT was twofold greater than that of nonsmoker lung alpha 1AT (smoker: 0.34 +/- 0.05 s vs. nonsmoker: 0.17 +/- 0.05 s, P less than 0.01). Consequently, for concentrations of alpha 1AT in the lower respiratory tract it takes twice as long for an equivalent amount of neutrophil elastase to be inhibited in the smoker's lung compared with the nonsmoker's lung. These observations support the concept that cigarette smoking is associated with a decrease in the lower respiratory tract neutrophil elastase inhibitory capacity, thus increasing the vulnerability of the lung to elastolytic destruction and thereby increasing the risk for the development of emphysema.

Alpha 1-antitrypsin deficiency and liver disease

Alpha 1-antitrypsin (alpha 1AT) deficiency, one of the most common lethal hereditary disorders among Caucasians, is associated with emphysema in adults, while in children it is associated with liver disease. Produced in the liver and released into the plasma, alpha 1AT serves as the body's major inhibitor of neutrophil elastase, a powerful proteolytic enzyme capable of degrading extracellular structural proteins. The pathogenesis of the liver disease associated with alpha 1AT deficiency is not as well understood, but is clearly linked to specific mutations in coding exons of the alpha 1AT gene, and the resulting accumulation of alpha 1AT within hepatocytes. At present, therapy for the liver disease associated with alpha 1AT deficiency is symptomatic, with liver transplantation as a last resort. New strategies are being developed to suppress the accumulation of alpha 1AT by transferring the normal gene into the liver.

Exclusion of an exon in monocyte alpha-1-antitrypsin mRNA after stimulation of U937 cells by interleukin-6

Monocytes potentially express two mRNA species by alternative splicing of exons at the 5' end of the gene. During inflammation the plasma concentration of AAT can increase about three-fold. In a myelomonocytic cell line (U937), under basal conditions, two AAT mRNA species are produced. After stimulation by interleukin-6 (IL-6) one mRNA species is produced resulting from the exclusion of the second monocyte exon. These findings demonstrate a novel way in which the expression of mRNA can be modified in a single cell type.

Molecular analysis of the heterogeneity among the P-family of alpha-1-antitrypsin alleles

The rare P-family of alpha 1-antitrypsin (alpha 1AT) variants is defined by the position of migration of the alpha 1AT protein on isoelectric focusing of serum (IEF) between the common M and S variants. To begin to examine the molecular heterogeneity among the P-type alleles, two unrelated subjects and their families identified by IEF to be carrying a P allele were analyzed. The first, Plowell, is a deficiency allele associated with reduced serum alpha 1AT levels, and the second, Psaint albans, is associated with normal serum levels. DNA sequence analysis of Plowell, the more anodal of the two variants on IEF analysis, showed that if differed from the normal M1(Val213) allele by a single base and amino acid substitution Asp256 GAT----Val GTT. In contrast, Psaint albans, a slightly more cathodally positioned variant on IEF analysis, differed from the coding exons of the normal M1(Val213) allele by two mutations, Asp341 GAC----Asn AAC, and a silent substitution in the same codon as the Plowell variant, Asp256 GAT----Asp GAC. Evaluation of Plowell mRNA transcripts by Northern and cytoblot analyses demonstrated they were of normal size and amount, and Plowell mRNA transcripts could be translated normally in vitro. Retroviral insertion of the Plowell cDNA into the genome of 3T3 fibroblasts demonstrated that it directed the synthesis of alpha 1AT, but at levels 24% that of the Psaint albans cDNA or the normal M1 (Val213) cDNA, with a pattern of biosynthesis consistent with the concept that the Plowell alpha 1AT deficiency state results from intracellular degradation of the newly synthesized Plowell protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of tumor necrosis factor secretion in leukocytes from alpha-1-antitrypsin deficient humans

Alpha-1-antitrypsin (AT) is one of several alpha-globulins which have been shown to be inhibitors of human peripheral blood monocyte TNF secretion in vitro. AT deficiency states exist, within which individuals of either the PiSS or PiZZ phenotype have reduced hepatocyte and mononuclear phagocyte AT secretion when compared to normal PiMM subjects. Here we have compared the capacity of peripheral blood monocytes of all three phenotypes to respond to both enhancers and inhibitors of TNF secretion. All monocytes exposed to lipopolysaccharide (LPS), interferon-gamma (IFN-gamma) and endotoxin, PGE2, transforming growth factor-beta 1, whole plasma alpha-globulins, purified AT and IL-6 responded equally with respect to the secretion of TNF. Our findings show that the regulation of TNF secretion in leukocytes from AT deficient humans is normal and suggest that defective AT secretion alone does not result in the aberrant regulation of TNF secretion.

Alpha 1-antitrypsin Wbethesda: molecular basis of an unusual alpha 1-antitrypsin deficiency variant

Molecular analysis of alpha 1-antitrypsin (alpha 1AT) Wbethesda revealed that it differs from the normal M1 (Ala213) allele by a single base mutation causing an amino acid substitution Ala336 GCT----Thr ACT. Evaluation of alpha 1AT biosynthesis directed by the Wbethesda allele showed that although Wbethesda alpha 1AT mRNA was translated normally in vitro, transfection of the Wbethesda cDNA into COS-I cells was associated with human alpha 1AT secretion of 50% that of cells transfected with a normal alpha 1AT cDNA. The pattern of alpha 1AT biosynthesis was not intracellular accumulation as observed with the common Z alpha 1AT deficiency allele, but reduced intracellular alpha 1AT, suggesting intracellular degradation of the newly synthesized Wbethesda molecule. Together these observations suggest that in heterozygous combination with a Z or Null alpha 1AT allele, the Wbethesda variant causes "alpha 1AT deficiency", thus classifying it as an alpha 1AT "at risk" allele for emphysema.

Alpha 1-antitrypsin deficiency, emphysema, and liver disease. Genetic basis and strategies for therapy

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Biased accumulation of T lymphocytes with "memory"-type CD45 leukocyte common antigen gene expression on the epithelial surface of the human lung

Expression of alternatively spliced products of the CD45 leukocyte common antigen gene identifies two populations of blood T cells: "naive" T cells (containing CD45R-IV mRNA transcripts, CD45 220, 205 kD surface proteins detected with antibody 2H4) that respond poorly to recall antigens, and "memory" T cells (containing CD45R-0 mRNA transcripts, expressing CD45 180 kD protein, detected with antibody UCHL1) that respond promptly to recall antigens. While blood contains approximately equal numbers of "naive" and "memory" T cells, it is known that UCHL1+ "memory" T cells accumulate at sites of chronic inflammation. To test the concept that "memory" T cells are a feature of the T lymphocyte populations present in tissues chronically exposed to antigens in normals as well as in individuals with chronic inflammation, we evaluated T lymphocytes obtained from blood and the epithelial surface of the lower respiratory tract of normal individuals for the expression of specific CD45 surface protein isoforms and corresponding mRNA transcripts. Flow cytometric analysis of CD45 220, 205, and 180 kD surface proteins demonstrated that lung T cells of normals are dominated by UCHL1+ "memory" cells (86 +/- 2%) while autologous blood T cells have equal proportions of "memory" UCHL1+ and "naive" 2H4+ T cells. In addition, polymerase chain reaction analysis of CD45 mRNA transcripts revealed that the lung cells expressed CD45R-0 mRNA transcripts but 17-fold fewer CD45R-IV mRNA transcripts than autologous blood T cells (p less than 0.01). The pattern of lung T cells being dominated by CD45R-0 mRNA+, UCHL1+ "memory" T cells was also observed in individuals with chronic beryllium disease, an example of a chronic inflammatory disease in which antigen-specific T cells accumulate on the pulmonary epithelial surface. Like the normals, the lung T cells of the beryllium disease patients were dominated by CD45R-0 mRNA transcript+, UCHL1+, T cells. However, on a quantitative basis, the beryllium patients contained far greater numbers of T cells, i.e., the T cell populations on the surface of the normal and inflamed lung are similar in character ("memory" T cells) but differ in numbers (there are far more in the chronic inflammatory state). Thus, T cell populations on the epithelial surface of the normal lung likely reflect the chronic exposure to a diverse set of antigens, with a pattern that is qualitatively similar to that observed among T cells accumulating in response to a single antigen.

Biosynthesis and secretion of M- and Z-type alpha 1-proteinase inhibitor by human monocytes. Effect of inhibitors of glycosylation and of oligosaccharide processing on secretion and function

The biosynthesis and secretion of M-type and Z-type alpha 1-antitrypsin was studied in human monocytes. In monocytes of PiMM individuals alpha 1-antitrypsin represented 0.08% of the newly synthesized proteins and 0.44% of the secreted proteins. Two molecular forms of alpha 1-antitrypsin could be identified: a 51-kDa intracellular form, susceptible to endoglucosaminidase H, thus representing the high-mannose type precursor form and a 56-kDa form resistant to endoglucosaminidase H which was secreted into the medium. Inhibition of de novo glycosylation by tunicamycin impaired the secretion of M-type alpha 1-antitrypsin by about 75% whereas inhibition of oligosaccharide processing by the mannosidase II inhibitor swainsonine did not alter the secretion of M-type alpha 1-antitrypsin. alpha 1-Antitrypsin secreted by human monocytes was functionally active as measured by complex formation with porcine pancreatic elastase. Even unglycosylated alpha 1-antitrypsin secreted by human monocytes treated with tunicamycin formed a complex with elastase. In monocytes of PiZZ individuals the secretion of alpha 1-antitrypsin was decreased. 72% of newly synthesized M-type alpha 1-antitrypsin, but only 35% of newly synthesized Z-type alpha 1-antitrypsin were secreted during a labeling period of 3 h with [35S]methionine. The 51-kDa form of Z-type alpha 1-antitrypsin accumulated intracellularly, whereas the 56-kDa form was secreted. Inhibition of oligosaccharide processing by swainsonine did not alter the decreased secretion of Z-type alpha 1-antitrypsin, whereas inhibition of de novo glycosylation by tunicamycin blocked the secretion of Z-type alpha 1-antitrypsin completely.

Molecular basis of alpha 1-antitrypsin deficiency and emphysema associated with the alpha 1-antitrypsin Mmineral springs allele

The Mmineral springs alpha 1-antitrypsin (alpha 1AT) allele, causing alpha 1AT deficiency and emphysema, is unique among the alpha 1AT-deficiency alleles in that it was observed in a black family, whereas most mutations causing alpha 1AT deficiency are confined to Caucasian populations of European descent. Immobilized pH gradient analysis of serum demonstrated that alpha 1AT Mmineral springs migrated cathodal to the normal M2 allele. Evaluation of Mmineral springs alpha 1AT as an inhibitor of neutrophil elastase, its natural substrate, demonstrated markedly lower than normal function. Characterization of the alpha 1AT Mmineral springs gene demonstrated that it differed from the common normal M1(Ala213) allele by a single-base substitution causing the amino acid substitution Gly-67 (GGG)----Glu-67 (GAG). Capitalizing on the fact that this mutation creates a polymorphism for the restriction endonuclease AvaII, family analysis demonstrated that the Mmineral springs alpha 1AT allele was transmitted in an autosomal-codominant fashion. Evaluation of genomic DNA showed that the index case was homozygous for the alpha 1AT Mmineral springs allele. Cytoplasmic blot analysis of blood monocytes of the Mmineral springs homozygote demonstrated levels of alpha 1AT mRNA transcripts comparable to those in cells of a normal M1 (Val213) homozygote control. Evaluation of in vitro translation of Mmineral springs alpha 1AT mRNA transcripts demonstrated a normal capacity to direct the translation of alpha 1AT. Evaluation of secretion of alpha 1AT by the blood monocytes by pulse-chase labeling with [35S]methionine, however, demonstrated less secretion by the Mmineral springs cells than normal cells. To characterize the posttranslational events causing the alpha 1AT-secretory defect associated with the alpha 1AT Mmineral springs gene, retroviral gene transfer was used to establish polyclonal populations of murine fibroblasts containing either a normal human M1 alpha 1AT cDNA or an Mmineral springs alpha 1AT cDNA and expressing comparable levels of human alpha 1AT mRNA transcripts. Pulse-chase labeling of these cells with [35S]methionine demonstrated less secretion of human alpha 1AT from the Mmineral springs cells than from the M1 cells, and evaluation of cell lysates also demonstrated lower amounts of intracellular human alpha 1AT in the Mmineral springs cells than in the normal M1 control cells. Thus, the Gly-67 --> Glu mutation that characterizes Mmineral springs causes reduced alpha 1AT secretion on the basis of aberrant posttranslational alpha 1AT biosynthesis by a mechanism distinct from that associated with the alpha 1AT Z allele, whereby intracellular aggregation of the mutant protein is etiologic of the alpha 1AT-secretory defect. Furthermore, for the alpha 1AT protein that does reach the circulation, this mutation markedly affects the ability of the molecule to inhibit neutrophil elastase; i.e., the alpha 1AT Mmineral springs allele predisposes to emphysema on the basis of serum apha 1AT deficiency coupled with alpha AT dysfunction.

Macrophages and polymorphonuclear neutrophils in lung defense and injury

Phagocytes, in particular macrophages and PMN, are now recognized as major components of inflammatory and immunologic reactions in the lung. Normally, macrophages represent the majority of phagocytes in the lower respiratory tract. These lung macrophages are morphologically and functionally heterogenous and include alveolar, interstitial, intravascular, and airway macrophages, each with characteristic morphologic and functional features. Through the presence of surface receptors for numerous ligands and through their large number of secretory products, lung macrophages can respond to environmental factors and account for most of the clearance of microparticles and microorganisms in the distal airways and the alveolar spaces. In addition, macrophages also play an important role in inflammatory processes through the release of oxygen radicals and proteolytic enzymes. Through the release of several cytokines, i.e., growth-promoting and inhibiting factors, lung macrophages may also influence both matrix damage and repair processes. Macrophages can also contribute to the alveolitis by recruitment of inflammatory and immune cells. This latter contribution is best demonstrated in migration movement of PMN. The normal distal airways generally contain a small number of PMN, but the pulmonary vascular bed represents a large reservoir of PMN. Some of them are in intimate contact with the endothelium, forming the so-called marginating pool of PMN. Because the capillary lumen is separated only from the alveolar space by a monolayer of endothelial and epithelial cells on each side of a thin interstitial matrix, it is likely that some inhibitory mechanism exists to prevent PMN from migrating towards the alveolar space. Such inhibitors of PMN migration are present both in serum and in the alveolar space, some being released by alveolar macrophages. However, alveolar macrophages can also secrete factors called chemotaxins that attract PMN to the airways, and this supports a central role for alveolar macrophages in the regulation of PMN traffic in the lungs. Thus, secretory products of alveolar macrophages are part of the regulatory mechanisms of PMN mobility and adherence that appears to be crucial in the initiation of some inflammatory reactions. The contribution of phagocytes to the defense against infection and tumor has been documented mostly in vitro. Thus, both oxygen radicals, in particular hydroxyl radicals and proteases such as lysozyme, are potent bactericidal agents. That phagocytes are also important defenders of the lungs in vivo is best supported by the observations in immunodeficient patients and animal models.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular basis of alpha 1-antitrypsin deficiency and emphysema associated with the alpha 1-antitrypsin Mmineral springs allele

The Mmineral springs alpha 1-antitrypsin (alpha 1AT) allele, causing alpha 1AT deficiency and emphysema, is unique among the alpha 1AT-deficiency alleles in that it was observed in a black family, whereas most mutations causing alpha 1AT deficiency are confined to Caucasian populations of European descent. Immobilized pH gradient analysis of serum demonstrated that alpha 1AT Mmineral springs migrated cathodal to the normal M2 allele. Evaluation of Mmineral springs alpha 1AT as an inhibitor of neutrophil elastase, its natural substrate, demonstrated markedly lower than normal function. Characterization of the alpha 1AT Mmineral springs gene demonstrated that it differed from the common normal M1(Ala213) allele by a single-base substitution causing the amino acid substitution Gly-67 (GGG)----Glu-67 (GAG). Capitalizing on the fact that this mutation creates a polymorphism for the restriction endonuclease AvaII, family analysis demonstrated that the Mmineral springs alpha 1AT allele was transmitted in an autosomal-codominant fashion. Evaluation of genomic DNA showed that the index case was homozygous for the alpha 1AT Mmineral springs allele. Cytoplasmic blot analysis of blood monocytes of the Mmineral springs homozygote demonstrated levels of alpha 1AT mRNA transcripts comparable to those in cells of a normal M1 (Val213) homozygote control. Evaluation of in vitro translation of Mmineral springs alpha 1AT mRNA transcripts demonstrated a normal capacity to direct the translation of alpha 1AT. Evaluation of secretion of alpha 1AT by the blood monocytes by pulse-chase labeling with [35S]methionine, however, demonstrated less secretion by the Mmineral springs cells than normal cells. To characterize the posttranslational events causing the alpha 1AT-secretory defect associated with the alpha 1AT Mmineral springs gene, retroviral gene transfer was used to establish polyclonal populations of murine fibroblasts containing either a normal human M1 alpha 1AT cDNA or an Mmineral springs alpha 1AT cDNA and expressing comparable levels of human alpha 1AT mRNA transcripts. Pulse-chase labeling of these cells with [35S]methionine demonstrated less secretion of human alpha 1AT from the Mmineral springs cells than from the M1 cells, and evaluation of cell lysates also demonstrated lower amounts of intracellular human alpha 1AT in the Mmineral springs cells than in the normal M1 control cells. Thus, the Gly-67 --> Glu mutation that characterizes Mmineral springs causes reduced alpha 1AT secretion on the basis of aberrant posttranslational alpha 1AT biosynthesis by a mechanism distinct from that associated with the alpha 1AT Z allele, whereby intracellular aggregation of the mutant protein is etiologic of the alpha 1AT-secretory defect. Furthermore, for the alpha 1AT protein that does reach the circulation, this mutation markedly affects the ability of the molecule to inhibit neutrophil elastase; i.e., the alpha 1AT Mmineral springs allele predisposes to emphysema on the basis of serum apha 1AT deficiency coupled with alpha AT dysfunction.

Characterization of the intracellular mechanism causing the alpha-1-antitrypsin Nullgranite falls deficiency state

The alpha-1-antitrypsin (alpha 1AT) Null alleles are those for which no alpha 1AT can be detected in the serum attributable to the gene. The intracellular consequences of the various substitution, deletion, and insertion mutations causing the Null state can be categorized into two groups: those associated with detectable alpha 1AT mRNA transcripts and those with no detectable alpha 1AT mRNA transcripts. To classify the intracellular mechanism associated with the Nullgranite falls allele (Tyr160 TAC, C deletion, 5' frameshift----Stop160 TAG), a Nullgranite falls homozygote was evaluated. Genotypic diagnosis of the Nullgranite falls homozygous state was determined using the polymerase chain reaction and Nullgranite falls specific primers. Total cellular RNA extracted from alveolar macrophages of the index case was compared to that from a normal M1 homozygote for the presence of alpha 1AT mRNA transcripts using Northern blot analysis and hybridization to either a 32P-labeled full length alpha 1AT cDNA probe or (as a control) a 32P-labeled gamma-actin cDNA probe. Although the macrophages of both the Nullgranite falls homozygote and the normal showed gamma-actin mRNA transcripts in comparable amounts, Nullgranite falls macrophages contained no detectable alpha 1AT mRNA transcripts whereas the normal had the expected 1.8 kb alpha 1AT mRNA transcripts. Thus, the Nullgranite falls allele can be classified along with Nullbellingham as a Null allele associated with no detectable alpha 1AT mRNA. These observations highlight the marked heterogeneity in the molecular processes causing the Null state, despite an identical phenotype at the clinical level.