Here, by using our recently generated LDLR heterozygote (<i>Ldlr+/-</i>) hamster model with functional LDLR pathway and CETP function, we seek to evaluate the effect of a PCSK9 antibody, evolocumab, on dyslipidemia and atherosclerosis compared with ezetimibe, an effective inhibitor of cholesterol absorption, as a positive therapeutic control.
While exposing the polygenic architecture of circulating lipids and the underpinnings of dyslipidaemia, these genome-wide association studies (GWAS) have provided further evidence of the critical role that lipids play in coronary heart disease (CHD) risk, as indicated by the 2.7-fold enrichment for macrophage gene expression in atherosclerotic plaques and the association of 25 loci (such as PCSK9, APOB, ABCG5-G8, KCNK5, LPL, HMGCR, NPC1L1, CETP, TRIB1, ABO, PMAIP1-MC4R, and LDLR) with CHD.
While gain-of-function mutations aggravate the degradation of LDLR as in familial hypercholesterolemia whereas loss of function mutations reduce the ability of PCSK9 to promote the degradation of LDLR and thus lower the plasma level of LDL-C and dyslipidemia.
Our findings indicate that, in well characterized FCHL individuals, variants in LDLR and LPL provide a small contribution to this dyslipidemia, thus limiting the need for such genetic testing.
ApoE4 which differs from apoE3 by the single amino acid substitution Cys112Arg is also associated with dyslipidemia although binding of this isoform to the LDLR is unaffected.
However, the LDL-receptor binding defects for these apoE variants do not correlate well with the severity of dyslipidemia, indicating that these variants may carry additional properties that contribute to their pathogenic potential.
Recent studies on LDL receptor-deficient mice that are hyperglycemic, but exhibit no marked dyslipidemia compared with nondiabetic controls, show that diabetes in the absence of diabetes-induced hyperlipidemia is associated with an accelerated formation of atherosclerotic lesions, similar to what is seen in fat-fed nondiabetic mice.
Gene replacement therapy of human low density lipoprotein (LDL) receptor gene into the murine model of FH transiently corrected the dyslipidaemia; however, humoral and cellular immune responses to LDL receptor developed--possibly contributing to the associated hepatitis and extinguishing of transgene expression.