Foam cells are white blood cells that have taken up oxidized low-density lipoprotein (LDL). After they accumulate large amounts of cytoplasmic membranes they become foam cells. Foam cells play an important role in the development of arteriosclerosis. A study by Napolitano et al. showed that lycopene inhibited the transformation of macrophage cells into foam cells, when treated with oxidized LDL . The researchers found that lycopene decreased the formation of cholesterol esters, decreased scavenger receptor activity but attenuated the production of anti-inflammatory cytokines. Although lycopene inhibited the formation of foam cells it also demonstrated a pro-inflammatory effect.
A study by the Changhai Hospital in China, led by Liu demonstrated that lycopene inhibited arteriosclerosis by reducing inflammatory agents in hyperhomocysteninemic rats . These are rats with elevated homocysteine blood levels, which are known to increase the risk of venous thrombosis. The researchers found that lycopene modulated the expression of inflammatory agents in a favorable manner: nitric oxide level (nitric oxide is produced by endothelial cells to relax surrounding smooth muscles, resulting in vasodilatation and increased blood flow) was increased whereas the levels of endothelin-1, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1 and interleukin-8 were reduced. . Another in-vitro study lead by Frederiksen showed no protective effect of lycopene on atherosclerosis, lipid oxidation or cholesterol level. They supplemented the diet of rabbits with a commercial tomato extract for 16 weeks. The plasma levels of lycopene increased significantly but no effect was observed on biochemical and cytological parameters.
A Taiwanese study showed that the intake of tomato products reduced platelet aggregation and could help to prevent trombosis. They came to this conclusion after treating stimulated human platelets with different levels of lycopene. The antiplatelet activity of lycopene may be caused by the inhibition of phospholipase C activation and activation of the formations of cyclic guanosine monophosphate.
 Napolitano M, De Pascale C, Wheeler-Jones C, Botham KM, Bravo E. "Effects of lycopene on the induction of foam cell formation by modified LDL." Am J Physiol Endocrinol Metab. 2007 Dec;293(6):E1820-7.
 Liu X, Qu D, He F, Lu Q, Wang J, Cai D. " Effect of lycopene on the vascular endothelial function and expression of inflammatory agents in hyperhomocysteinemic rats." Asia Pac J Clin Nutr. 2007;16
 Frederiksen H, Rasmussen SE, Schrøder M, Bysted A, Jakobsen J, Frandsen H, Ravn-Haren G, Mortensen A. " Dietary supplementation with an extract of lycopene-rich tomatoes does not reduce atherosclerosis in Watanabe Heritable Hyperlipidemic rabbits." Br J Nutr. 2007 Jan;97(1):6-10.
 Hsiao G, Wang Y, Tzu NH, Fong TH, Shen MY, Lin KH, Chou DS, Sheu JR. "Inhibitory effects of lycopene on in vitro platelet activation and in vivo prevention of thrombus formation." J Lab Clin Med. 2005 Oct;146(4):216-26.