Aneurysm or occlusive disease--factors determining the clinical course of atherosclerosis of the infrarenal aorta.
Atherosclerosis of the infrarenal aorta results in distinct clinical entities--aortoiliac occlusive disease (AOD) and abdominal aortic aneurysm (AAA). Although loss of collagen has been implicated in AAA, collagen accumulation plays a role in AOD. In vivo collagen-gene expression can be assessed using complementary DNA for collagen types I and III alpha-chains. The purpose of this study is to compare total collagen (type I + III) and collagen types I and III messenger RNA in AAA, AOD and normal aorta. Specimens were collected from the infrarenal aorta during operation for AOD (n = 7), AAA (n = 7), autopsy, or organ procurement (normal; n = 7). Northern transfer analysis of total RNA was used to compare mRNA levels for type I and III collagen. After preliminary extraction, specimens were hydrolyzed for hydroxyproline analysis used to calculate total collagen (type I + III). Relative levels of type I (pro-a1[1]) mRNA were greater in both AOD (0.77 +/- 0.35) and AAA tissue (0.94 +/- 0.24; p = 0.6) than in normal aorta (0.02 +/- 0.03). Type III (pro-a1[III]) mRNA levels were also greater in AOD (2.52 +/- 0.19; p = 0.09) and AAA tissue (3.15 +/- 1.3) than in normals (0.97 +/- 0.47). Total collagen concentration was increased in AOD (45.6% +/- 3.1% dry weight; p less than 0.05) but not AAA tissue (27.8% +/- 4%) when compared to normal aorta (34.7% +/- 2.3%). Collagen type I and III gene expression is greater in older, diseased aorta, yet collagen accumulated only in AOD. This implies a similar synthetic response in both AOD and AAA. Thus, proteolytic degradation in AAA appears to determine collagen content and possibly the clinical course of the atherosclerotic process.
McGee
G S
GS
Department of Surgery, Feinberg Cardiovascular Institute, Chicago, Ill.
Baxter
B T
BT
Shively
V P
VP
Chisholm
R
R
McCarthy
W J
WJ
Flinn
W R
WR
Yao
J S
JS
Pearce
W H
WH
D000368:Aged; D001012:Aorta, Abdominal / Q000737:chemistry; D001014:Aortic Aneurysm / Q000209:etiology / Q000378:metabolism*; D001157:Arterial Occlusive Diseases / Q000209:etiology / Q000378:metabolism*; D001161:Arteriosclerosis / Q000150:complications*; D015152:Blotting, Northern; D003094:Collagen / Q000032:analysis* / Q000235:genetics; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007083:Iliac Artery; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis
D012333:RNA, Messenger; D003094:Collagen