Content and turnover of extracellular matrix protein in human “Non-specific” and inflammatory abdominal aortic aneurysms

Abstract

Inflammatory aneurysms (IAs) have peculiar macroscopic and histological aspects which make them very different from nonspecific aneurysms (NSAs). These morphological differences seem to be determined by significant modifications of the extracellular matrix. Extracellular matrix protein component concentrations were determined biochemically in infrarenal aortic biopsies from 10 NSAs, five IAs and five non-aneurysmal aortic controls. The concentration of each wall component was expressed in % w/w (relative concentration) and in mg/wall longitudinal cm (absolute concentration) with reference to total protein recovered after hydrolysis and amino acid analysis. The biochemical results were correlated with the histological and ultrastructural features of the specimens. A significant increase in total collagen was observed in the two groups of aneurysms, with respect to the controls (NSA = 285%, IA = 382%). In contrast the 80-90% decrease in the relative concentration of elastin observed in both types of aneurysm was less marked (NSA = 55%, IA = 39%). This fall was not significant when expressed in mg/cm, although elastin derived peptide (EDP) levels in the plasma of these patients was significantly higher than in age-matched controls. The concentration of the soluble collagen fraction appeared significantly higher (Mann-Whitney, p < 0.05) in the IAs with respect to the NSAs, whilst no differences were observed between the two groups regarding the concentration of insoluble elastin and of wall and plasma EDPs. As well as providing evidence of increased elastin turnover, this study emphasises the conspicuous modifications of collagen deposition in the wall of abdominal aortic aneurysms which appeared more marked in the inflammatory group.(ABSTRACT TRUNCATED AT 250 WORDS)