Human aortic intima protein composition during initial stages of atherogenesis

Protein extracted from 24 human aortic intimas (6–33 years old) with 9 M urea mixture, were studied after separation by two-dimensional gel electrophoresis (2-DE) and silver staining. The protein composition of normal intima in 4 cases, each without any gross changes in the thoracic aorta, displayed similarity. In each 2-DE protein pattern of these intimas about 150 polypeptide spots were detectable/mg of wet tissue. Major and medium polypeptides were described by relative molecular weight M r in kilodaltons (kDa) and relative charge C r. Major proteins found were actin (P 44−18; M r = 44 kDa; C r = −18), tropomyosin-like proteins (P 34−29, P 35−28.5, P 36−31) and two glycoproteins (G 35−27, G 35−23.5). Several new major and medium extracellular proteins were demonstrated in fibro-fatty lesions as well as in the lesion-free intimas adjacent to lesion in 3 cases. Many of these proteins appeared to originate from plasma: albumin, IgG, α 1-antitrypsin, transferrin, haptoglobin β-chain, apo A-II, fibrinogen β-chain, α 2-HS glycoprotein and α 1-antichymotrypsin. Visual comparison of intimal protein patterns from 17 different cases with varying degree of fatty streaks in the thoracic aorta, showed variability in 2 polypeptides P 32−17.8 and P 32–19.8 as well as 4 plasma proteins albumin, at-antitrypsin, transferrin and apo A-I. This study suggests that changes in protein composition may occur in the human aortic intima during the initial histological stages of atherogenesis providing potentially useful markers for their identification and pathophysiological evaluation.