Inflammatory Markers and Genes: Epidemiologic Studies on their Roles in Cardiovascular Disease

Established cardiovascular risk factors such as hypertension, hyperlipidemia, diabetes mellitus and smoking do not fully explain the occurrence of cardiovascular disease; although the majority of patients have at least one of these risk factors, a substantial proportion of cases occurs in individuals that have none.1 As such, further insight is required into the pathophysiology of cardiovascular disease and in factors that may identify individuals at high risk. One of the most relevant insights in atherosclerosis of the past years is the recognition of the role of inflammation.2 Research on inflammatory markers, both experimental and epidemiological, has taken flight, and several of these markers have been implicated in cardiovascular disease.3 This development was accompanied by an expansion of research on genetic variation that may influence inflammatory processes. The field of genetics has rapidly evolved over the last years because of improved technology and methodology in combination with the emergence of large, publicly available genetic databases.4 The purpose of this thesis was to expand the knowledge on inflammatory markers and inflammatory genes that may play a part in the pathophysiology of cardiovascular disease. We focused on factors that have drawn increased attention in the recent years, such as C-reactive protein (CRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2), and examined their roles in both atherothrombotic disease and in heart failure. Most studies were conducted within the Rotterdam Study, a population- based cohort study among 7983 men and women aged 55 years and over living in a well-defined suburb of Rotterdam, the Netherlands.5 During a visit of the participants to the research center, blood was drawn in order to assess inflammatory markers and genetic variation. Several measures of atherosclerosis were assessed at the research center, and furthermore, participants were followed-up for the occurrence of coronary events and heart failure. Specifically, the main research questions we examined were as follows. With regard to inflammation, atherosclerosis and coronary events: - Is CRP serum level associated with atherosclerosis and coronary events? - Is variation in the CRP gene and variation in the complement factor H gene associated with coronary events, and do these genes interact to predict disease? - Is Lp-PLA2 activity associated with atherosclerosis? With regard to inflammation and heart failure: - What is the distribution of echocardiographic parameters in an asymptomatic population, and do these parameters predict mortality? - Are the inflammatory markers CRP and Lp-PLA2 associated with the occurrence of heart failure?