Worldwide the incidence of diabetes mellitus type 2 (DM2) is increasing and present an ever growing factor of expenditure in the health systems of especially the western world. At the time of diagnosis about 50% of these patients exhibit complications, especially in the form of atherosclerosis. The development of atherosclerosis and atherothrombosis may be delayed by intensive treatment of dyslipidemia, insulin resistance and dysrequlation of diabetes as well.
Typically, risk factors for atherothrombosis in diabetes patients are monitored on blood samples such as measurements of the regulation of diabetes (HbAlc) combined with measurements of cholesterol fractions and triglycerides (dyslipidemia). ECG, sensitive CRP, and marker enzymes of heart ischemia are used for screening of cardiac atherosclerosis and thrombosis as well as for diagnostic and monitoring purposes.
Additionally, it is necessary to evaluate clinical symptoms of atherosclerosis thus involving a complex range of tests and clinical evaluations in order to obtain a realistic assessment of the risk factors.
An integrated measurement of the level and risk of atherosclerosis and/or atherothrombosis in patients, such as diabetes patients, would facilitate and enable early intervention thus providing considerable health and economic gains.
Griffin, E. et al. (Nature Medicine, Vol. 7, No. 7, July 2001, pp 840-846) have shown that a glucose mediated increase in CD36 mRNA translation efficiency results in increased expression of the macrophage scavenger receptor CD36 and that expression of CD36 was increased in endarterectomy lesions from patients with a history of hyperglycemia. Thus, the increased translation of CD36 transcripts under high glucose conditions provides a mechanism for accelerated atherosclerosis in diabetics. Griffin et al. use immunocytochemistry on human carotid artery lesions and human peripheral blood mononuclear cells to detect the levels of CD36 expression.
Liang C-P et al.(JCI113:763-73, 2004) found, in a study using macrophages from ob/ob mice, evidence that an increased CD36 protein expression in insulin resistant macrophages is caused by defective insulin signalling, and that defective macrophage insulin signalling predisposes to foam cell formation and atherosclerosis in insulin-resistant states. JP published patent application No. 2000180447 describes a method and a reaction kit for detecting a CD36 antigen in an organism sample such as blood as a marker for the presence of and/or the degree of acute myocardial infarction. However, a correlation between the presence of CD36 antigen in a blood sample of a patient or subject and a risk of said patient or subject developing atherosclerosis is not shown or mentioned in JP 2000180447.
Moreover, it is known that a drop in the CD36 levels in cells of a patient after initiating protease inhibitor therapy relative to the level prior to protease inhibitor therapy is predictive of the subsequent development of lipodystrophy associated with antiretroviral therapy. The level of CD36 is measured in cells using flow cytometric analysis. The cells may be monocytes from a blood sample or a fraction thereof (CA patent application No. 2289365).
Thus, it appears that measurements of the membrane bound CD36 protein as a marker molecule for atherosclerosis related conditions has a diagnostic potential. However, with the present state of the art, such measurements will involve the use of immunocytochemistry and/or flow cytometry which require the use of complicated apparatuses and which are not readily useful for a standard hospital laboratory.
There is a need for a simple and cost efficient method to predict those at risk of developing atherosclerosis and/or atherothrombosis. Said method would provide an integrated measurement of the influence of several risk factors in one analysis of a blood plasma sample by measuring the level of a circulating analyte such as an unbound protein or fraction thereof or soluble complex comprising said protein or fraction present in blood plasma.