Mycophenolate mofetil treatment reduces cholesterol-induced atherosclerosis in the rabbit

Immunosuppressive therapy has been shown to either improve or, more frequently, enhance the development of atherosclerosis. We tested the effect of mycophenolate mofetil (MMF), an inhibitor of nucleotide synthesis widely used in transplant therapy, in diet-induced atherosclerosis in the rabbit. Two groups (n=10 each) of New Zealand White (NZW) rabbits were fed a 1% cholesterol diet for 12 weeks. One group received MMF (CHOL+MMF group) by gastric gavage (30 mg/kg daily) and the other group (CHOL) received the same volume of saline by the same route. There were no differences in the serum cholesterol (mean values > or =30 mmol/l in both groups after 2 weeks) or in the triglyceride, blood sugar, total protein, and albumin serum levels and weight gain in both groups of animals. The cholesterol-fed untreated rabbits had atherosclerotic plaques covering 43.9.1+/-SD 16.40% of their thoracic aorta and 41.9+/-22. 59% of their abdominal aorta, while the MMF treated group had 18. 5+/-7.17% and 17.7+/-9.71%, respectively (P<0.01). The cholesterol content of the aorta (mg/g) in the cholesterol-fed untreated group was 4.61+/-SD 1.21 in the thoracic aorta and 4.54+/-2.07 in the abdominal aorta, whereas the MMF treated group had and 2.83+/-0.84 and 2.77+/-1.44, respectively (P<0.01). Infiltrating macrophages (RAM 11 positive cells/100 nuclei) in the intimal layer of the aorta were 58.4+/-SD26.16 in the CHOL group and 8.5+/-5.51 in the CHOL+MMF group: (P<0.001). CD18 positive cells/100 nuclei were 27.4+/-17.6 in the CHOL group and 5.3+/-3.82 in the CHOL+MMF group (P<0.01), and the intima/media ratio was 0.66+/-0.11 in the CHOL group and 0. 30+/-0.09 in the MMF treated rabbits (P<0.001). MMF also reduced proliferating smooth muscle cells (HHF35 positive) infiltrating between the macrophages. These results indicate that MMF ameliorates importantly the atherogenic potential of a high cholesterol diet and this effect is associated with a reduction in macrophage and foam cell infiltration and smooth muscle cell proliferation and infiltration. Since chronic treatment with this drug is given routinely in various clinical conditions with relatively minor side effects, consideration may be given to its use as adjuvant therapy in atherosclerotic cardiovascular disease.