Atherogenesis: the role of inflammation and infection.

Atherosclerosis is no longer considered a disorder of lipid accumulation, but a disease process characterized by the dynamic interaction between endothelial dysfunction, subendothelial inflammation and the 'wound healing response' of the vascular smooth muscle cells. Prospective epidemiological studies have unequivocally demonstrated increased vascular risk in individuals with elevated levels of (i) cytokines such as interleukin-6 and tumour necrosis factor-alpha, (ii) cell adhesion molecules such as intercellular adhesion molecule-1 and P-selectin, and (iii) acute-phase proteins such as C-reactive protein, fibrinogen and serum amyloid A. Furthermore, evidence from clinical trials have demonstrated that risk reduction achieved with anti-inflammatory agents such as statins is significantly greater in patients with evidence of inflammation. A number of risk factors for atherogenesis, including infectious agents, have been shown to exert their influence via inflammatory mechanisms. However, despite compelling experimental evidence, clinical studies looking at the role of infection in atherogenesis have lacked consistency. The clinical product of this dynamic process is variable and unpredictable between individuals, even those with apparently similar risk profiles.