Collagen and elastin gene expression in aortic aneurysms

Background. The decreased elastin concentration found in abdominal aortic aneurysms (AAAs) may result from a differential synthetic response wherein elastin gene expression fails to increase in parallel with type I procollagen (COL I) gene expression. The purpose of this study is to determine tissue mRNA levels for elastin and COL I in AAAs compared with levels in normal, age-matched aorta and to determine the relationship between aging and COL I gene expression. Methods. Total RNA exacted from normal infrarenal aortic tissue (n = 7) and AAA (n = 10) tissue was subjected to Northern analysis. Mean values for COL I, elastin, and α-tubulin mRNA levels were compared by use of the Student t test. Age and COL I mRNA levels were analyzed by regression analysis. Results. COL I mRNA was increased significantly in AAAs (1.18 ± 0.13) compared with normal aortas (0.14 ± 0.05). A commensurate increase in elastin mRNA (AAAs, 0.11 ± 0.02, vs normal aortas, 0.39 ± 0.2) was absent. There was no correlation between age and COL gene expression. Conclusions. The decreased elastin concentration relative to collagen in AAAs may be explained, in part, by the changes in message level of elastin and collagen. The enhanced COL I gene expression in AAAs is unrelated to age.