Purification and partial characterization of elastase activity from rat alveolar and peritoneal macrophages

Role of elastin in spontaneously hypertensive rat small mesenteric artery remodelling

Chronic hypertension is associated with resistance artery remodelling and mechanical alterations. However, the contribution of elastin has not been thoroughly studied. Our objective was to evaluate the role of elastin in vascular remodelling of mesenteric resistance arteries (MRA) from spontaneously hypertensive rats (SHR). MRA segments from Wistar Kyoto rats (WKY) and SHR were pressurised under passive conditions at a range of physiological pressures with pressure myography. Confocal microscopy was used to determine differences in the quantity and organisation of elastin in intact pressure-fixed arteries. To assess the contribution of elastin to MRA structure and mechanics, myograph-mounted vessels were studied before and after elastase incubation. When compared with WKY, MRA from SHR showed: (1) a smaller lumen, (2) decreased distensibility at low pressures, (3) a leftward shift of the stress-strain relationship, (4) redistribution of elastin within the internal elastic lamina (IEL) leading to smaller fenestrae but no change in fenestrae number or elastin amount. Elastase incubation (1) fragmented the structure of IEL in a concentration-dependent fashion, (2) abolished all the structural and mechanical differences between strains, and (3) decreased distensibility at low pressures. The study shows the overriding role of elastin in determining vascular dimensions and mechanical properties in a resistance artery. In addition, it informs hypertensive remodelling. MRA remodelling and increased stiffness are accompanied by elastin restructuring within the IEL and elastin degradation reverses structural and mechanical alterations of SHR MRA. Differences in elastin organisation are, therefore, a central element in small artery remodelling in hypertension.

Proteinases and proteinase inhibitors during the development of pulmonary fibrosis in rat

Changes in the activities of several proteinases and their inhibitors were investigated during the development of bleomycin-induced pulmonary fibrosis in rat. Studies on the proteinase-anti-proteinase-ratio may contribute to the understanding of the mechanism of the development of pulmonary fibrosis and may help to develop therapeutic strategies to prevent tissue damage by proteolytic attack. In the acute inflammatory period the activity of metalloelastase in lung tissue increased by about 10-fold. The time course of changes in the activity of 72 kD gelatinase indicates that this gelatinase accounts at least partially for the elastolytic activity. Elastase inhibitory activity in lung tissue showed maxima at days 1 and 5 and high levels in the fibrotic phase. The increase of the elastase inhibitory activity at the beginning of the fibrotic period corresponds with elevated activity of alpha 2-macroglobulin. Alveolar fluid and alveolar macrophages did not contain elastase activity but contained high elastase inhibitory activity. During the period of chronic inflammation, the activities of the cathepsins L, B, H and S in lung tissue and in isolated alveolar macrophages were found to be strongly increased.

An elastolytic proteinase from rabbit leukocytes: purification and partial characterization

A proteinase with elastolytic activity was isolated from granules of rabbit bloodstream leukocytes, and purified to apparent homogeneity by a multi-step procedure consisting of ammonium sulfate precipitation, batch fractionation on DEAE-Sephadex A-50, and finally by preparative isoelectric focusing (IEF) on Sephadex G-75 Superfine. The molecule weight of the enzyme, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), was 28,500. This enzyme shows an isoelectric point at pH 9.0. The proteinase is active against natural elastins as well as toward Suc-(Ala)3-NA, Methoxy-Suc-(Ala)2-Pro-Val-NA, and (to a lesser extent) against Suc-(Ala)2-Pro-Leu-NA and Boc-Ala-ONp. The inhibition profile of the isolated enzyme indicates that rabbit granulocyte elastase belongs to the group of serine proteinases. Inhibition by some natural proteinase inhibitors is also observed. Unlike other mammalian elastases, it is insensitive to elastatinal.