Apolipoprotein E-depletion accelerates arterial fat deposition in the spontaneously hypertensive rat

Hypertension and atherosclerosis are often found in one patient causing serious cardiovascular events. An animal model simultaneously expressing hypertension and atherosclerosis would be useful to study such a complex risk status. We therefore attempted to introduce a null mutation of the apolipoprotein E (ApoE) gene into the spontaneously hypertensive rat (SHR) using CRISPR/Cas9 to establish a genetic model for atherosclerosis with hypertension. We successfully established SHR^ApoE(-/-) having a 13-bps deletion in the 5'-end of ApoE gene. Deletion of ApoE protein was confirmed by Western blotting. Blood pressure of SHR^ApoE(-/-) was comparable to that of SHR. Feeding the rats with high fat high cholesterol diet (HFD) caused a significant increase in LDL cholesterol as well as in triglyceride in SHR^ApoE(-/-). After 8 weeks of HFD loading, superficial fat deposition was observed both in the aorta and the mesenteric arteries of SHR^ApoE(-/-) instead of mature atheromatous lesions found in humans. In addition, a null mutation of peroxiredoxin 2 (Prdx2) was introduced into SHR^ApoE(-/-) to examine the effect of increased oxidative stress on the development of atherosclerosis. SHR with the double depletion of ApoE and Prdx2 did not show mature atheroma either. Further, salt loading did not promote development of atheroma although it accelerated the development of fat deposition. These results indicated that when compared with ApoE-knockout mice, SHR^ApoE(-/-) was more resistant to atherosclerosis even though they have severe hypertension.