Background: Previous studies of urine proteome patterns in humans using capillary electrophoresis coupled to mass spectrometry (CE-MS) allowed the identification of polypeptide patterns indicative of coronary artery disease in symptomatic patients. The aim of this study is the use of urine proteomics in ApoE-/- mice to diagnose early stages of atherosclerosis, to establish a monitoring tool for anti-atherosclerotic interventions, and to establish a discovery tool for novel proteins driving atherosclerosis.
Methods and Results: Urine of ApoE-/- mice either on high fat diet (HFD) or regular diet (RD) was collected at different time points after initiation of diet (after 0, 7, 9, 12 and 15 weeks); urine of wild-type mice on HFD and RD was used to exclude diet-related changes in proteome pattern. CE-MS of 64 urine specimens showed a specific upregulation of 16 polypeptides in ApoE-/- mice on HFD. In a blinded test set of another 21 urine specimens, markers were further validated and allowed the differentiation of ApoE-/- mice on HFD vs. RD with a sensitivity of 95% and specificity of 90%. Sequencing of polypeptides identified collagen type I, α1-antitrypsin, epidermal growth factor (EGF), and kidney androgen regulated protein (KAP). To provide further confirmation that the newly identified proteins are relevant in humans, presence of collagen type I, α1-antitrypsin, and EGF was also confirmed in human atherosclerotic plaque using Immuno-histochemistry.
Conclusion: Urine proteome analysis allows the noninvasive detection of early atherosclerosis and can be used to monitor anti-atherosclerotic therapy and represents a novel discovery tool for the identification of proteins relevant in atherogenesis and which are potential therapeutic targets.