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The tight-skin (Tsk) mouse is a genetic model of pulmonary emphysema. In this mouse, right ventricular hypertrophy (RVH) starts to develop at approximately 8 months of age, probably as a consequence of the emphysema. The aim of the present study was to investigate cardiac collagen synthesis, content, and types both before and during the development of RVH. Collagen synthesis, assessed by the [3H]proline incorporation method, was significantly increased in the right ventricle of 3-month-old Tsk mice. This was accompanied by a marked increase in right ventricle collagen content. Collagen typing showed no difference from controls. At 8 months of age collagen synthesis had returned to control values, right ventricular collagen content was elevated but held lower values than at 3 months, and collagen typing showed a prevalence of the more compliant type III. By 16 months of age, right ventricular collagen content had returned to control values and there was a shift in collagen types due to a relative increase of the more rigid type I. At 24 months of age right ventricular collagen content was increased again and collagen type I continued to predominate. These results suggest a dynamic role for collagen both before and during the development of RVH secondary to emphysema.

Diffuse subtypes of cutaneous lymphoid hyperplasia (CLH; n = 18) and primary malignant follicular center cell lymphoma of the skin (FCCL, n = 11) were diagnosed by conventional histology, immunophenotyping on paraffin sections, and gene rearrangement analysis. We then counted on semithin, Azur A-stained sections of resin-re-embedded biopsy specimens the relative numbers of apoptotic bodies among all lymphoid cells (apoptotic index [AI]). The diagnostic value of AI was compared to that of mitotic indices (MI) and percentages of various cell types in the cutaneous infiltrate. Features of cellular infiltrates distinguishing to two groups of lesions, in the order of decreasing significance, were percent large lymphoid cells, percent medium-sized lymphoid cells (both higher in FCCL); percent small lymphoid cells, percent epithelioid/giant cells, and percent histiocytes/macrophages (all three higher in CLH). However, of all parameters tested, AI had the greatest discriminant value (median in FCCL 1.11%, in CLH 0.14%; p = 8 x 10(-6)). Two cases, diagnosed as CLH with all morphologic and immunologic methods used, showed B-cell monoclonality at the DNA level. Linear discriminant analysis determined the following order of distinctive power of variables: 1) AI; 2) MI; 3) percent small lymphoid cells; 4) percent medium-sized lymphoid cells; 5) percent large lymphoid cells; 6) percent epithelioid/giant cells; and 7) percent histiocytes/macrophages. The present study thus establishes AI as an important parameter in the differentiation of diffuse CLH from diffuse cutaneous FCCL.

The tight-skin (Tsk) mouse is a genetic model of pulmonary emphysema linked to a deficiency of serum antielastase. In this mouse occurrence of connective tissue abnormalities in various organs (systemic scleroderma) has been reported. The aim of the present work was to study lung collagen synthesis and deposition in Tsk mice. No differences in the collagen synthesis rate and morphology at the ultrastructural level were found in Tsk mice at birth. At 2 months of age, a marked increase in collagen was observed within the alveolar septa. At this time, an increased lung collagen synthesis, assessed by determining prolyl hydroxylase activity and incorporation of radiolabeled proline, was found in Tsk mice with respect to control mice. However, due to the ongoing parenchymal destruction, the values of total lung collagen at 6 and 12 months of age were only moderately but significantly increased with respect to those observed at 2 months. As a consequence, a progressive accumulation of lung collagen fibers was observed in the residual septa. The increase in collagen deposition was accompanied by a relative increase in type I collagen. Although the data in the literature would suggest a genetic cause for the lung collagen change in Tsk mice, the data presented here indicate that the change in lung collagen metabolism may be a part of a remodeling process taking place after lung destruction.

Although an elastolytic activity in eosinophil-rich cell fractions from mice has been reported, this enzyme has not been purified and characterized as yet in any mammalian species. Eosinophilic elastase was isolated from human eosinophil fragments (cytosomes) obtained from normal and eosinophilic subjects. The enzyme was purified to apparent electrophoretic homogeneity by fast protein liquid chromatography. The enzyme shows the same physical properties of the major elastase isoenzyme of human neutrophils. In addition, like monocyte elastase, it reacts with a monoclonal antibody against human neutrophil elastase. The biochemical similarities observed between the above-mentioned enzymes and the immunolocalization findings strongly support the idea that human eosinophils and neutrophils contain the same enzyme activity. Eosinophils show immunoreactive material in both types of dense cytoplasmic granules. This observation supports the current hypothesis that the different types of eosinophilic granules represent successive morphological stages of maturation.

The tight-skin (Tsk) mouse is a model of genetically determined emphysema. The cause for the development of the lung lesion is unknown. In the present study we investigated the lung morphometry and the serum elastase inhibitory capacity (EIC) of Tsk mice. Mean interalveolar distance was significantly greater (+60%) in Tsk mice than in C57 Bl/6J, NMRI, and Balb/c mice, which have similar values. Serum of Tsk mice against mouse leukocyte elastase (MLE) has significantly lower EIC values than that of NMRI, Balb/c (-64%), and C57 Bl/6J (-50%) mice. Similar results were obtained when porcine pancreatic elastase (PPE) was used. Against human leukocyte elastase (HLE), however, there was no difference among the strains, all of which had high EIC values. Preincubation of mouse (C57 Bl/6J) serum with chloramine-T (CT) resulted in an almost complete inhibition of EIC against MLE and PPE but only in a 20% inhibition against HLE using a synthetic substrate. Using elastin Congo Red as substrate, CT inhibited EIC against MLE and PPE by approximately 70% but did not affect the EIC against HLE. These results indicate that (1) the Tsk mouse can be considered a model of severe inborn deficiency of serum antielastase activity which is associated with emphysema; and (2) MLE and PPE can be considered interchangeable in studies of serum EIC in the mouse. On the other hand, the differences between MLE and HLE preclude the use of HLE for EIC determination in this species.

The tight-skin (Tsk) mouse has recently been proposed as a genetic model of emphysema. In the present study, the development of emphysema was investigated in these mice with histological, biochemical, and ultrastructural methods at 4 days and at 1 and 2 months of life. At 4 days after birth, histological examination of the lungs revealed only a mild enlargement of the primary sacculi. Neither biochemical nor ultrastructural changes were seen however at this time. At 1 month of age, the histological examination showed marked emphysema-like changes, characterized by enlargment of air spaces accompanied by destruction of alveolar walls. Biochemical analysis showed a marked decrease in insoluble elastin content and a significant increase in salt-extractable collagen. Ultrastructural investigation revealed edema fluid in the interstitium and broken and disorganized elastic fibers. All these findings strikingly resemble the changes which occur in the lungs early after an instillation of elastase. In the 2-month-old Tsk mice the histological lesion progressed in severity. The ultrastructural findings were similar to those observed at 1 month, and the biochemical changes showed no signs of recovery. Thus, in these mice, the emphysematous lesion develops very rapidly between 4 days and 1 month of life and shows the characteristics of an elastolytic process which is still ongoing at 2 months of age.

The tight-skin (Tsk) mouse has recently been proposed as a genetic model of emphysema. A morphometric study has shown that emphysema develops quickly, between 15 days and 1 month after birth. Previous biochemical and ultrastructural investigations of the lungs of 1- and 2-month-old Tsk mice revealed the presence of an ongoing elastolytic process. The goal of the present study was to investigate the role of mouse leukocyte elastase (MLE) in the development of emphysema in 1-month-old Tsk mice. Using electron microscopy and an immunogold labeling technique with rabbit anti-MLE IgG, MLE was localized within the lung neutrophils of control and Tsk mice. MLE was also found associated with elastin in the alveolar septa of Tsk but not of control mice. Little or no labeling was associated with other components (collagen, pneumocytes, and endothelium) of alveolar septa of Tsk mice. Lung elastin of control mice, or of control mice rendered emphysematous with porcine pancreatic elastase, showed negligible gold particle density when incubated with gold-conjugated rabbit IgG. Thus, under the present experimental conditions, an aspecific labeling of elastin is unlikely. This study indicates that MLE may be one of the factors responsible for the rapid development of emphysema in Tsk mice.

Using an experimental model of pancreatitis in the rat, the role of trypsin and elastase in mediating lung vascular injury in this condition was examined. The induction of pancreatitis by injection of sodium cholate in the pancreas resulted in a significant decrease in serum trypsin inhibitory capacity, and in a complete saturation of serum elastase inhibitory capacity matched by the appearance of endothelial injury of pulmonary capillaries and edema formation. The complete lack of serum elastase inhibitory capacity was associated with the presence of elastase activity in serum and bronchoalveolar lavage (BAL) fluids. The pretreatment of animals with N-furoyl saccharin (a potent inhibitor of many serine proteinases) prevented lung capillary injury and the imbalance of serum proteinase-anti-proteinase activities as well as the appearance of any elastolytic activity in serum and BAL fluids. These findings which clearly demonstrate the protease dependence of the pulmonary vascular injury in our experimental model, strongly suggested a major role for elastase(s). The suppression, in the experimental model, of the serum elastase inhibitory capacity by using chloramine-T resulted in an earlier onset of lung vascular damage, a marked worsening of pulmonary lesions, and an increase of elastolytic levels in serum and BAL fluids. Furthermore the physical properties of the protein molecule with enzyme activity detected in BAL fluids were consistent with those of rat pancreatic elastase. The reported data strongly support the hypothesis that pancreatic elastase plays a major role in the development of pulmonary vascular injury after acute pancreatitis.