Collagen characterisation and cell transformation in human atherosclerosis

Abstract

COLLAGEN comprises 40–60% of the protein^1,2 and 30% of the weight³ of human fibrous atherosclerotic plaques. Its deposition in the arterial intima is largely responsible for the occlusive and irreversible nature of coronary and cerebral arterial disease. Four genetically distinct types of collagen have been identified in mammalian tissues and atleast five structural genes are involved in their synthesis⁴. The transcription of these various genes seems to be tissue specific. Type I collagen is found in tendon, bone and adult skin, type II is found in cartilage and intervertebral disk, and type IV is restricted to basement membrane. Type III collagen was observed first in newborn human skin⁵ and has been isolated and characterised from human aorta and leiomyoma⁶. Initial reports identified both types I and III in human aorta^4,7. We have now found that fibrous atherosclerotic plaques contain proportions of these two collagens which are different from those occurring in normal arterial wall.