Spontaneous pneumothorax and alpha 1-antitrypsin deficiency

Spontaneous pneumothorax has been observed in patients with abnormal levels of alpha 1-antitrypsin. We report the case of a young woman with a low level of alpha 1-antitrypsin who presented with recurrent episodes of spontaneous pneumothorax and who required pleuroscopy, apical lung resection, and pleurodesis.     

Decreased leukotriene B4 synthesis in smokers' alveolar macrophages in vitro

Recent studies have shown that alveolar macrophages (AM) are able to release leukotrienes (LTs). Since cigarette smoking inhibits the cyclooxygenase pathway of arachidonic acid metabolism in the AM, we evaluated the LT production by AM from smokers and nonsmokers. AM were obtained from 35 volunteers, 16 nonsmokers, and 19 smokers. The cells were incubated under various conditions including stimulation with 30 microM arachidonic acid, 2 microM ionophore A23187, or both. Each experiment was performed in parallel using cells from a smoker and a nonsmoker. Lipoxygenase products were analyzed by reverse-phase high performance liquid chromatography. After stimulation, nonsmokers' AM produced LTB4 and 5-hydroxy-eicosatetraenoic acid (5-HETE). In incubations of AM with arachidonic acid and ionophore, the amounts of products formed were: LTB4, 317 +/- 56 pmol/10(6) cells and 5-HETE, 1,079 +/- 254, mean +/- SEM. No metabolites were generated under control conditions (no stimulation). In all incubations performed, the peptido-LTs (LTC4, LTD4, and LTE4) were undetectable. In comparison with AM from nonsmokers, those from smokers showed a 80-90% reduction of 5-HETE and LTB4 synthesis (P less than 0.05 to P less than 0.001 according to stimulatory conditions). This defective lipoxygenase metabolite production in AM from smokers was observed over a wide range of stimuli concentrations and incubation times; AM from smokers also had lower levels of intracellular (esterified) 5-HETE than nonsmokers' AM. We also studied blood polymorphonuclear leukocytes (PMNL) and no difference in the synthesis of 5-lipoxygenase products in these cells was noticed between smokers and nonsmokers. These data show that cigarette smoking causes a profound inhibition of the 5-lipoxygenase pathway in AM but not in blood PMNL.     

Recombinant interferon-gamma primes alveolar macrophages cultured in vitro for the release of leukotriene B4 in response to IgG stimulation

The capacity of interferon-gamma to regulate the generation and release of leukotriene B4 (LTB4) from human alveolar macrophages of normal nonsmoking individuals was evaluated. When alveolar macrophages were incubated for 60 min with heat aggregated IgG (HAIgG), they generated and released 5.7 +/- 1.7 ng of LT B4 per 10(6) cells compared to 1.9 +/- 0.4 ng from cells incubated with buffer alone, P = 0.02. When alveolar macrophages were preincubated with interferon-gamma for 24 h before activation for 60 min with heat-aggregated IgG, the soluble IgG aggregates became a significantly more effective stimulus for LTB4 release, 17.0 +/- 3.9 ng/10(6) cells, P = 0.001, compared to cells incubated in the absence of interferon-gamma and challenged with HAIgG. Interferon-gamma did not alter the response to A23187. This effect of interferon-gamma was both time and dose dependent; it also was specific since neither interferon-alpha nor interferon-beta had a regulatory effect on the release of LTB4 from cells in response to challenge with HAIgG. Preincubation of the alveolar macrophages with interferon-gamma augmented the density of IgG1 receptors by 81.5 +/- 17.3%; neither interferon-alpha nor interferon-beta effected this parameter. Furthermore, monomeric IgG1 blocked HAIgG induced LTB4 release from alveolar macrophages primed with interferon-gamma. Therefore, at least one of the mechanisms by which interferon-gamma primes alveolar macrophages for the production and release of LTB4 in response to stimulation by aggregates of IgG is that of increasing the number of receptors for this stimulus.     

Dexamethasone inhibits the production of thromboxane B2 and leukotriene B4 by human alveolar and peritoneal macrophages in culture

Cultured human alveolar and peritoneal macrophages have been shown to release thromboxane B2 and leukotriene B4. The release was facilitated by stimulation of the macrophages with opsonized zymosan A (1.2 mg/ml). The release was inhibited in a concentration-dependent manner by incubation of the cells with dexamethasone (1 nmol/l to 1 mumol/l).     

Characterization of leukotriene B4 binding sites on guinea pig lung macrophages

Specific binding sites for [3H]leukotriene B4 (LTB4) were identified on guinea pig lung macrophages, using high specific activity [3H] LTB4 in the presence or absence of unlabeled LTB4. At 0 degrees C, [3H] LTB4 binding reached equilibrium within 30 min, and addition of a large excess of unlabeled LTB4 resulted in a rapid decrease of specific binding. Binding was saturable, reversible and dependent upon the number of lung macrophages. The KD and Bmax were found to be 3.85 +/- 0.6 nM and 35 +/- 3 fmol/10(6) cells, respectively, as determined from Scatchard analysis. In competition studies for the displacement of [3H]LTB4 from binding sites, LTB4 and its analogs had the following order of potency: LTB4 (Ki = 2.9 +/- 0.8 nM) greater than 5-epi LTB4 (Ki = 58.7 +/- 0.3 nM) greater than 5-deoxy-LTB4 (Ki = 91.7 +/- 0.3 nM) greater than 12-epi LTB4 (Ki = 4.7 +/- 1.2 microM) greater than 5,12-deoxy LTB4 (Ki = 7.6 +/- 0.01 microM) greater than or equal to 12-deoxy LTB4 (Ki = 8.9 +/- 0.01 microM). LTC4 and LTD4 did not displace the [3H] LTB4 binding at concentrations up to 10 microM. [3H]LTB4 was not metabolized during the binding process as determined by reverse-phase high performance liquid chromatography. It was suggested that this binding site might be an LTB4 receptor.     

Replacement therapy of alpha 1-antitrypsin deficiency. Reversal of protease-antiprotease imbalance within the alveolar structures of PiZ subjects.

The emphysema associated with the inherited serum deficiency of alpha 1-antitrypsin appears to result from an imbalance between neutrophil elastase and its major inhibitor within the alveolar structures. In the present study we assessed the feasibility of reversing this biochemical defect within the lung via parenteral replacement therapy with an alpha 1-antitrypsin concentrate of normal plasma. A 20--40% polyethylene glycol precipitate of pooled human donor plasma was used to obtain an enriched alpha 1-antitrypsin concentrate devoid of hepatitis B antigen and immunoglobulins. Using this material, five individuals with severe serum alpha 1-antitrypsin deficiency (PiZ phenotype) and advanced emphysema received 4 g of alpha 1-antitrypsin intravenously at weekly intervals for four doses. During this period of weekly replacement therapy alpha 1-antitrypsin serum levels were maintained at greater than or equal to 70 mg/dl, the level likely required for effective antielastase protection of the lung. In addition, assessment of lower respiratory tract antielastase activity by bronchoalveolar lavage demonstrated that parenteral replacement of alpha 1-antitrypsin resulted in establishment of effective antielastase activity within the alveolar structures. There were no untoward side effects consequent to this approach to the replacement therapy of alpha 1-antitrypsin. These results demonstrate that the parenteral replacement of alpha 1-antitrypsin provides a means of obtaining elastase-antielastase balance within the lung of individuals with this serum protease inhibitor deficiency.     

Recombinant DNA-produced alpha 1-antitrypsin administered by aerosol augments lower respiratory tract antineutrophil elastase defenses in individuals with alpha 1-antitrypsin deficiency.

Alpha 1-Antitrypsin (alpha 1AT) deficiency is characterized by insufficient amounts of alpha 1AT to protect the lower respiratory tract from neutrophil elastase, resulting in emphysema. Yeast-produced recombinant alpha 1AT (rAAT) has normal antielastase function but is associated with high renal clearance, thus obviating chronic intravenous administration. As an alternative, we evaluated aerosol administration of rAAT to alpha 1AT-deficient individuals. After aerosol administration of single doses of 10-200 mg of rAAT, epithelial lining fluid (ELF) alpha 1AT antineutrophil elastase defenses were augmented in proportion to the dose of rAAT administered. ELF alpha 1AT levels and antineutrophil elastase capacity 4 h after 200 mg rAAT aerosol were increased 40-fold over preaerosol levels, and were fivefold increased over baseline at 24 h after aerosol administration. rAAT was detectable in serum after aerosol, indicating that the lower respiratory tract epithelium may be permeable to rAAT, and that aerosolized rAAT is capable of gaining access to lung interstitium. No adverse clinical effects were noted. These observations demonstrate that aerosol administration of rAAT is safe and results in significant augmentation of lung antineutrophil elastase defenses, suggesting this method is a feasible approach to therapy. Because this approach is clinically unproven, further studies will be necessary to establish the long-term clinical efficacy of aerosol therapy in alpha 1AT deficiency.     

alpha 2-Macroglobulin in patients with obstructive lung disease, with and without alpha 1-antitrypsin deficiency

Serum alpha 2-macroglobulin concentrations were measured in 178 patients with emphysema and 115 control subjects of similar age and sex distribution. The study group included 59 PI type Z patients with alpha 1-antitrypsin deficiency, five with the rare alpha 1-antitrypsin null genotype (PI Q0 or --), and seven with alpha 1-antitrypsin deficiency of the rare PI types MmaltonZ or MduarteZ. Individuals with all types of alpha 1-antitrypsin deficiency were found to have significantly increased serum concentrations of alpha 2M (p less than 0.001). These increased concentrations were associated with all types of alpha 1-antitrypsin deficiency, not only with the PI type Z. The highest alpha 2-macroglobulin concentrations were found in the PI Q0 patients (5 with emphysema, 2 with no lung disease), and these patients had almost no circulating alpha 1-antitrypsin. Raised concentrations of serum alpha 2-macroglobulin were not due to emphysema: 86 patients with emphysema, of PI type M, and the normal control subjects had similar average concentrations of alpha 2-macroglobulin. One control subject with an average alpha 2-macroglobulin concentration of only 41% of normal was found.     

Systemic necrotizing vasculitides in severe alpha1-antitrypsin deficiency

We describe the clinical presentation and outcome in a series of eight patients with systemic necrotizing vasculitis and severe alpha1-antitrypsin (AAT) deficiency followed up at three Swedish hospitals during 1968-92. We also review six other cases reported in the literature during the same period. Diagnosis of severe AAT deficiency was based on the presence of the PiZZ phenotype, or low plasma total trypsin inhibitory capacity, or a low plasma AAT concentration (10-40% of the normal mean value) and presence of the PiSZ or PiFZ phenotype. The diagnosis of systemic vasculitis was biopsy-verified in all eight patients. Pretreatment laboratory findings, treatment protocol, and outcome were reviewed in each of the 14 patients. Of the eight patients in the Swedish series, six had systemic vasculitis of the microscopic polyangiitis form, one had Wegener's granulomatosis, and another had Henoch-Schonlein purpura. In the series as a whole (n=14), median age at diagnosis was 48 years (range 44-84), the median number of affected organs was eight, and all 14 patients had skin involvement, and either renal or joint involvement (in most cases both); 71% (10/14) had emphysema; 57% (8/14) had hepatic abnormalities (two having cirrhosis, two fibrosis, and one multiple aneurysms in hepatic arteries); one patient who presented with acute ulcerative colitis developed manifest vasculitic syndrome three years later; and 64% (9/14) died, the major cause of death being renal failure. This syndrome, characterized by multiple organ involvement and fatal outcome, has been underdiagnosed. Physicians should be alert to the presence of the PiZ AAT deficiency gene in patients with systemic vasculitis, especially when the course is progressive or when the patient also has emphysema or cirrhosis. Awareness of those features may aid prompt recognition and enable early treatment.      

Spontaneous hydrogen peroxide release from alveolar macrophages of some cigarette smokers

Alveolar macrophages were retrieved by bronchoalveolar lavage (BAL) from 30 patients, 24 smokers and six nonsmokers. The macrophages were separated from other cells in the BAL fluid by glass adherence. The amount of hydrogen peroxide released into the media by these macrophages was then measured by a new method of determining hydrogen peroxide concentration. Two groups were found. Group 1, who did not spontaneously release hydrogen peroxide, were mostly nonsmokers (six of nine), and group 2, who spontaneously secreted hydrogen peroxide (87.5 +/- 17.08 nmol/10(6) macrophages [mean +/- SEM]), were all smokers (21 of 21). When the alveolar macrophages in group 1 were stimulated with phorbol myristate acetate, they secreted as much hydrogen peroxide as the stimulated macrophages of group 2 (group 1: 125.0 +/- 92.08 nmol/10(6) macrophages, group 2: 116.7 +/- 14.82 nmol/10(6) macrophages). We conclude that there is a subset of smokers whose alveolar macrophages spontaneously release hydrogen peroxide.     

Principles and clinical management of alpha 1-antitrypsin deficiency

Alpha 1-antitrypsin (alpha 1-AT) deficiency can cause a lung disease that, until a few years ago, has proved fatal to all patients diagnosed with this disease. This deficiency can now be treated with alpha 1-proteinase inhibitor, a protein derived from human plasma and delivered via intravenous infusion. Infusion therapy for alpha 1-AT deficiency can be delivered in the hospital or home environments. This article discusses the pathophysiology of alpha 1-AT deficiency and outlines nursing considerations for the intravenous clinician who is administering this therapy.     

Molecular mousetraps, alpha1-antitrypsin deficiency and the serpinopathies

Point mutations in members of the serine proteinase inhibitor or serpin superfamily cause them to change shape, polymerise and be deposited in the tissues. This process is best seen in mutants of alpha1-antitrypsin within hepatocytes to cause periodic acid-Schiff (PAS) positive inclusions and cirrhosis. An identical process underlies the PAS positive inclusions of mutants of neuroserpin within neurones to cause a dementia that we have called familial encephalopathy with neuroserpin inclusion bodies (FENIB). In both cases, there is a direct correlation between the molecular instability, the rate of intracellular polymer formation and the severity of disease. This process of polymerisation also explains the failure to secrete mutants of other members of the serpin superfamily--antithrombin, C1 inhibitor and alpha1-antichymotrypsin--to cause thrombosis, angio-oedema and emphysema, respectively. In view of the common mechanism underlying these conditions, we have grouped them together as the serpinopathies.     

New insights into the structural basis of alpha 1-antitrypsin deficiency

The serpin superfamily of serine proteinase inhibitors contains many members but the best-characterized is the plasma protein alpha 1- antitrypsin. its genetic deficiency is associated, in the homozygote, with hepatic damage that may progress to cirrhosis and hepatocellular carcinoma. Low levels of circulating alpha 1-antitrypsin fail to protect the lungs against proteolytic attack and predispose the homozygote to early onset pan-lobular emphysema, bronchiectasis and asthma. The major cause of alpha 1-antitrypsin deficiency, the Z mutation (Glu342Lys), results in the accumulation of protein in the endoplasmic reticulum of the liver. Using a structural approach, we have shown that the hepatic inclusions result from a protein-protein interaction between the reactive centre loop of one molecule and the beta-pleated sheet of a second. This loop-sheet polymerization is now also recognized to be the basis of deficiencies associated with mutations of C1-inhibitor, antithrombin and alpha 1-antichymotrypsin. Our recent solution of a crystal structure of a thermostable mutant of alpha 1-antitrypsin shows the detailed interactions that result in loop- sheet linkage and helps to explain the mechanism of action of this family of proteinase inhibitors.      

Effects of leukotriene B4 in the human lung. Recruitment of neutrophils into the alveolar spaces without a change in protein permeability.

Leukotriene B4 (LTB4) is a major product of human alveolar macrophages and has potent chemotactic activity for neutrophils (PMN) in vitro. To evaluate the effects of LTB4 in the normal human lung, we instilled LTB4 (5 X 10(-7)M, 10 ml) into a subsegment of the right middle lobe and 0.9% NaCl (10 ml) into a subsegment of the lingula using a fiberoptic bronchoscope in 12 healthy human volunteers. 4 h later, we performed bronchoalveolar lavage of the same subsegments. Compared with the NaCl instillation, LTB4 caused a large increase in lavage total cells (NaCl = 6.8 +/- 1.0 X 10(6) vs. LTB4 = 26.4 +/- 5.0 X 10(6), P less than 0.01), most of which were PMN (NaCl = 12.2 +/- 4.6% vs. LTB4 = 55.7 +/- 6.0%, P less than 0.001). In contrast, there was only a small increase in lavage total protein, and the lavage total protein correlated weakly with lavage total cells and PMN. The production of superoxide anion by the lavage PMN in response to phorbol myristate acetate was similar to that of peripheral blood PMN. The migration of lavage PMN was normal toward the chemotactic peptide FMLP, but reduced toward LTB4 and zymosan-activated human serum. Morphometric analysis using transmission electron microscopy indicated a selective loss of small granules in the lung neutrophils as compared with peripheral blood neutrophils. The data indicate that in the normal human lung, LTB4 can recruit active PMN into the airspaces without causing a significant change in the protein permeability of the epithelial barrier.     

Emphysema in nonsmokers: alpha 1-antitrypsin deficiency and other causes

Nonsmokers with signs of emphysema at an earlier age than is typical for emphysema deserve a workup for one of the less common causes of emphysema, which include alpha 1-antitrypsin deficiency, connective tissue diseases, hypocomplementemic urticarial vasculitis syndrome, intravenous drug use, human immunodeficiency virus infection, and several rare metabolic disorders.     

Modulation of alveolar macrophage leukotriene B4 released by complement component C5

The release of neutrophil chemotactic activity by the guinea pig alveolar macrophage (AM) is dependent on the fifth component of complement (C5) on the cell surface. Because one potent chemotactic factor released by AMs is leukotriene B4 (LTB4), we hypothesized that cell surface C5 may modulate LTB4 release. To test this hypothesis, human AMs obtained by bronchoalveolar lavage from 12 subjects were cultured for 4 hours in the presence of anti-C5 Fab' antibodies with stimuli. The cultures were harvested and evaluated for LTB4 by radioimmunoassay. The LTB4 levels in supernatants obtained from AMs cultured in media alone were variable (447 +/- 63 pg/ml), but the levels were increased when AMs were cultured with the stimuli-opsonized zymosan, immune complexes, or lipopolysaccharide (233%, 49%, and 114% increase, respectively, compared with macrophages cultured in media alone, p less than 0.05). Culturing the AMs with anti-C5 Fab' antibodies inhibited the release of LTB4 induced by opsonized zymosan, immune complexes, or lipopolysaccharide (78%, 41%, and 82% inhibition, respectively, p less than 0.05). Consistent with these observations, anti-C5 Fab' antibodies also decreased the neutrophil chemotactic activity of culture supernatants obtained from AMs stimulated with the same stimuli (p less than 0.001). These data suggest that AM release of LTB4 may be C5-dependent.