The pathogenesis of pulmonary emphysema.
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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.
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The definition and the classification of bullae are recalled and documented by some examples. Two types of bullae are opposed : bulla found in normal parenchyma and bulla associated with widespread emphysematous lesions. The biochemical and biological mechanisms of the emphysematous changes are briefly described, with a distinction of two different pathogenesis : on one hand, an inherited defect in connective tissue synthesis as in Marfan syndrome, and on the other hand, an unbalance between proteases and antiproteases. The pathologist's contribution to the classification of the surgical forms of emphysema is documented by an electron microscopic study of lung biopsy in some cases : two cases with bullae (a Marfan syndrome and an alpha 1 AT deficiency of the Pi Z phenotype) with diffuse panlobular emphysema; and 4 cases of bullae without radiological evidence of emphysema. The elastic fibres were modified only in the 2 first cases but were normal in the others. A follow up of such cases is needed.
The characteristics of emphysema and cirrhosis in Pi ZZ (alpha-1-antitrypsin deficiency) and SZ patients are reviewed. The clinical and laboratory data have been incorporated into a simple hypothesis on the development of these diseases. The PiZ protein can not be secreted normally from the liver cells. The accumulation of alpha-1-antitrypsin in the liver may result in cirrhosis, and the deficiency in serum to emphysema.
Previously, it had been shown that T-lymphocytes are the predominant inflammatory cells found in the alveolar wall of smokers and their numbers correlated with the extent of emphysema. However, the phenotype of these cells was not defined. The aim of this study was to describe the different T-cell phenotypes and investigate the possible presence of apoptosis in the lung parenchyma of smokers. Samples from lungs were obtained at surgery from 15 patients who smoked and six who had never smoked. Samples were frozen and prepared for histological and immunocytochemical examination. Slides were stained for CD3+, CD4+, CD8+, gammadelta T-cells, CD56 natural killers ((NK) cells), and elastase (neutrophils). Anti-CD95 monoclonal antibodies and in situ end-labelling techniques were used to detect Fas expression and apoptosis. Positive staining cells were expressed as cells-mm alveolar wall-, percentage of total cells, and Fas/APO and apoptosis index. Emphysema was identified macroscopically, microscopically and reported as present or absent. All subjects had pulmonary function tests before surgery. Neutrophils were the predominant cell in the lung parenchyma of nonsmokers and smokers without emphysema. In smokers with emphysema, the CD3+ and CD8+ were the predominant cells (p<0.05) in the alveolar wall. gammadelta cells were increased in all smokers and no increased numbers of NK cells was found. The T-cell numbers x mm alveolar wall(-1) showed a bilinear relationship with the amount smoked increasing at an inflection point of 30 packs yr(-1) (R2= 0.345; p < 0.01). Apoptosis in smokers showed a bilinear relationship with the amount smoked increasing sharply in smokers with emphysema (R2=0.3613; p < 0.009). It is concluded that the pathogenesis of emphysema might be mediated by T-lymphocytes, mainly CD8+ cytolytic T-cells, and that apoptosis might be one of the mechanisms of lung destruction leading to the development of emphysema. If this is the case, it could be speculated that T-cell inflammation is a response to antigenic stimuli originating in the lung and induced by cigarette smoking.
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The core fucosylation (alpha1,6-fucosylation) of glycoprotein is widely distributed in mammalian tissues. Recently alpha1,6-fucosylation has been further reported to be very crucial by the study of alpha1,6-fucosyltransferase (Fut8)-knock-out mice, which shows the phenotype of emphysema-like changes in the lung and severe growth retardation. In this study, we extensively investigated the effect of core fucosylation on alpha3beta1 integrin and found for the first time that Fut8 makes an important contribution to the functions of this integrin. The role of core fucosylation in alpha3beta1 integrin-mediated events has been studied by using Fut8(+/+) and Fut8(-/-) embryonic fibroblasts, respectively. We found that the core fucosylation of alpha3beta1 integrin, the major receptor for laminin 5, was abundant in Fut8(+/+) cells but was totally abolished in Fut8(-/-) cells, which was associated with the deficient migration mediated by alpha3beta1 integrin in Fut8(-/-) cells. Moreover integrin-mediated cell signaling was reduced in Fut8(-/-) cells. The reintroduction of Fut8 potentially restored laminin 5-induced migration and intracellular signaling. Collectively, these results suggested that core fucosylation is essential for the functions of alpha3beta1 integrin.
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Klotho mice, which exhibit multiple phenotypes resembling human aging, develop pulmonary emphysema. In this study, to clarify the mechanism of their emphysematous change through development, we evaluated the expression of matrix metalloproteinase (MMP)-2, 9 and the tissue inhibitors of matrix metalloproteinase (TIMP)-1, 2 in the lungs of Klotho mice and wild type mice. Klotho mice showed obvious air space enlargement at 5 weeks of age, but not at 2 weeks of age. Immunohistochemical analysis revealed that expression of MMP-9 was increased in Klotho mice compared with wild type at 5 weeks of age. Western blot analysis and gelatin zymography also revealed that the expression and the gelatinolytic activity of MMP-9 were increased in the lungs of Klotho mice. The expression of TIMP-1 decreased in the lungs of Klotho mice. MMP-2 and TIMP-2 showed no significant differences at 5 weeks of age. At 2 weeks of age, there were no significant differences in the expressions of MMP-9 and TIMP-1 between Klotho and wild type mice. These findings suggest that imbalance of MMP-9 and TIMP-1 is associated with the development of pulmonary emphysema in Klotho mice.
A case is described of Niemann-Pick type C2 disease presenting an infantile pneumopathic phenotype known to occur in this recently established, second, minor complementation group of Niemann-Pick type C (NPC) disease. However, the pulmonary involvement was unique, being dominated, in addition to the usual storage macrophage infiltration of the alveolar and septal compartments, by irregular emphysema attributed to storage cell migration into the bronchiolar lumen. The latter modified considerably the X-ray findings and hindered the initial clinical diagnosis. Otherwise, the storage phenotype, including the range of stored lipids, storage distribution, and cell and organ pathology, was found to be identical to that in the whole Niemann-Pick type C disease group dominated by NPC1. The biochemical findings (cholesterol esterification level) corresponded to the classical biochemical phenotype. Emphysema should thus be considered as a variant of the pulmonary NPC2 storage process, governed most probably by an epigenetic mechanism responsible for storage macrophage migration into the bronchiolar compartment.
We present three patients with homozygous alpha-1-antitrypsin deficiency and pulmonary emphysema. They demonstrate the typical patterns of this syndrome: panlobular emphysema, early age of onset, serum alpha-1-antitrypsin below 35% of normal and phenotype PiZZ. We discuss epidemiology, pathogenesis and clinical manifestations, and review the experience concerning replacement therapy using alpha-1-antitrypsin derived from human plasma. We strongly point out the importance of stopping cigarette smoking in such patients.
An increased risk for the development of emphysema occurs in all carriers of deficient variants of Alpha-1-Antitrypsin (A1AT). A DNA polymorphism in the 3' promoter region of A1AT gene (locus Pi), which is important for a modulation of gene expression in a response to inflammation, seems to be an additional genetic risk factor for emphysema. In the study, we present two relatively young patients with panlobular lung emphysema associated with a normal level of A1AT in serum. To contribute to our knowledge about a molecular basis of the pulmonary changes, the evaluation of A1AT phenotype with the use of an isoelectrofocusing of serum proteins and the analysis of DNA polymorphism in the 3' region of A1AT gene (Taq I RFLP) have been performed. The obtained results indicate on a necessity to include procedures of A1AT phenotyping and locus Pi genotyping in both the population screening of patients and the detailed clinical diagnostics of young patients with emphysema and/or COPD.
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