Expression of PDGF-A, TGFb and VCAM-1 during the developmental stages of experimental atherosclerosis

A considerable number of growth factors, cytokines, and adhesion molecules are implicated in the development of atherosclerotic lesions. These molecules interact in a complex network influencing the evolution of several processes, such as lipid metabolism, cellular proliferation and tissue repair. The aim of this study was to evaluate the expression of the growth factors PDGF-A, and TGFb, and the adhesion molecule VCAM-1 in the sequential steps of experimental atherogenesis.

Forty-two New Zealand white male rabbits were divided into 4 groups. The group A rabbits (n = 8) received normal diet and served as control animals. The remaining groups were fed with a diet enriched with 1% cholesterol and 6% corn oil. The rabbits of group B (n = 9) were sacrificed 1 month after the beginning of the study, of group C (n = 15) after 2 months and of group D (n = 10) after 3 months. In tissue sections of the aortic arch the antibodies of the prementioned factors were detected immunohistochemically.

In group A only TGFb and PDGF-A were detectable. In lesions of the first month PDGF-A expression was high but declined towards the third month. VCAM-1 expression was getting more intense up to the second month and subsided thereafter. TGFb expression intensified towards the third month. Changes in the expression of these factors were statistically significant.

PDGF-A, responsible for the uncontrollable growth of smooth muscle cells, and VCAM-1, regulating monocyte recruitment in the intima, acts mainly during the early stages of atherogenesis. TGFb, one of the main factors controlling the formation of connective tissue matrix, has a gradually increasing expression towards the third month contributing probably to the fibrous plaque formation.