Objective-Cyclosporin A (CsA) is an immunosuppressant commonly used to prevent organ rejection but is associated with hyperlipidemia and an increased risk of cardiovascular disease. Although studies suggest that CsA-induced hyperlipidemia is mediated by inhibition of low-density lipoprotein receptor (LDLr)-mediated lipoprotein clearance, the data supporting this are inconclusive. We therefore sought to investigate the role of the LDLr in CsA-induced hyperlipidemia by using Ldlr-knockout mice (Ldlr-/-). Approach and Results-Ldlr-/- and wild-Type (wt) C57Bl/6 mice were treated with 20 mg/kg per d CsA for 4 weeks. On a chow diet, CsA caused marked dyslipidemia in Ldlr-/- but not in wt mice. Hyperlipidemia was characterized by a prominent increase in plasma very low-density lipoprotein and intermediate-density lipoprotein/LDL with unchanged plasma high-density lipoprotein levels, thus mimicking the dyslipidemic profile observed in humans. Analysis of specific lipid species by liquid chromatography-Tandem mass spectrometry suggested a predominant effect of CsA on increased very low-density lipoprotein-IDL/LDL lipoprotein number rather than composition. Mechanistic studies indicated that CsA did not alter hepatic lipoprotein production but did inhibit plasma clearance and hepatic uptake of [14C]cholesteryl oleate and glycerol tri[3H]oleate-double-labeled very low-density lipoprotein-like particles. Further studies showed that CsA inhibited plasma lipoprotein lipase activity and increased levels of apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9. Conclusions-We demonstrate that CsA does not cause hyperlipidemia via direct effects on the LDLr. Rather, LDLr deficiency plays an important permissive role for CsA-induced hyperlipidemia, which is associated with abnormal lipoprotein clearance, decreased lipoprotein lipase activity, and increased levels of apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9. Enhancing LDLr and lipoprotein lipase activity and decreasing apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9 levels may therefore provide attractive treatment targets for patients with hyperlipidemia receiving CsA.
- apolipoprotein C-III
- Cyclosporin A
- Proprotein convertase subtilisin/kexin type 9