Author + information
- Gemma Vilahur, PhD∗ (, )
- Manuel Gutiérrez, MD,
- Laura Casaní, PhD, DVM,
- Judit Cubedo, PhD,
- Antoni Capdevila, MD,
- Guillem Pons-Llado, MD,
- Francesc Carreras, MD,
- Alberto Hidalgo, MD and
- Lina Badimon, PhD
- ↵∗Cardiovascular Research Center, Hospital de la Santa Creu i Sant Pau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
Epidemiological studies have consistently reported that high-density lipoprotein (HDL) cholesterol levels are inversely associated with the risk of cardiovascular disease (CVD) (1). In fact, plasma-derived and synthetic HDL, and/or its derivatives, have been shown to exert various cardiovascular protective effects ranging from reverse cholesterol transport, atherosclerotic plaque stabilization, improvement of endothelial dysfunction (2), and most lately, limiting infarct size (3). However, in this latter regard, it remains unknown whether the presence of cardiovascular risk factors attenuates HDL-related cardiovascular protection. We investigated whether the presence of high low-density lipoprotein cholesterol levels, a prominent risk factor for CVD, affects ability of HDL to exert direct cardioprotective effects. We conducted this study in a pre-clinical animal model of myocardial infarction (MI) as a biological readout of the differential effects of HDL when formed in a high-cholesterol pathological environment.
Young healthy pigs were distributed to receive during 10 days either a regular normocholesterolemic chow (NC) or a high-cholesterol diet (HyC) (non-HDL cholesterol 38.2 ± 3.5 mg/dl vs. 218.6 ± 27.6 mg/dl, respectively; p < 0.0001). On day 10, HDLs were isolated from NC- and HyC-fed animals by sequential ultracentrifugation (NCHDL and HyCHDL, respectively) and were quantified, sterilized, lyophilized, and kept at −80°C until use. Another set of young healthy pigs were randomized to receive 2 intravenous infusions 3 days apart of NCHDL (15 mg/kg; n = 6), HyCHDL (15 mg/kg; n = 6), or vehicle (phosphate-buffered saline; n = 6). One day after the second infusion, animals were subjected to 60-min closed-chest coronary balloon occlusion followed by reperfusion (experimental MI). Echocardiography revealed that 60 min of ischemia significantly and similarly worsened left ventricle ejection fraction in all animals showing the homogeneity of the employed methodological approach (vehicle: 19.6 ± 4.8%; NCHDL: 20.6 ± 3.2%; HyCHDL: 17.3 ± 2.1%; p < 0.05 vs. prior MI induction). Three days post-MI, all animals underwent cardiac magnetic resonance, and the following sequences were acquired: 1) “cine” (balanced steady-state free precession) imaging sequence to assess wall motion and cardiac function; 2) T2-short tau inversion recovery sequence to assess myocardial edema; 3) T2* to evaluate intramyocardial hemorrhage; 4) early gadolinium enhancement to evaluate the degree of no-reflow; and 5) late gadolinium enhancement to assess the extent of myocardial necrosis. Data were normally distributed (Shapiro-Wilk Test) and analysis of variance, Fisher least significant difference, and post-hoc Student-Newman-Keuls analyses were performed. A value of p < 0.05 was considered significant.
Infusion of NCHDL before MI resulted in a significantly smaller infarct size, in terms of both absolute infarct mass and percentage of the left ventricle, compared with vehicle-infused animals (Table 1). This protective effect did not occur in animals infused with HyCHDL. T2-weighted sequences revealed no differences in the extent of area-at-risk among the 3 groups. Consequently, the extent of salvage myocardium was significantly larger in the NCHDL-administered group compared with the HyCHDL and vehicle control groups. The extent of no-reflow was also significantly attenuated in the NCHDL-infused group compared with HyCHDL and vehicle animals and directly correlated with the extent of necrosis (p < 0.05; R = 0.63). No differences were observed between HyCHDL-recipient animals and vehicle controls with regard to infarct size, myocardial salvage, and no-reflow. The extent of hemorrhage was comparable among the 3 groups. Although left ventricular ejection fraction assessed 3 days post-MI did not differ between the groups (Table 1), left ventricular volumes significantly improved in NCHDL-recipient animals compared with HyCHDL- and vehicle-infused animals.
We describe, for the first time, that hypercholesterolemia, a common risk factor for CVD, impairs the cardioprotective properties commonly associated with HDL. We provide evidence that HDL particles formed in a high low-density lipoprotein cholesterol niche lose their capability to attenuate myocardial damage in the setting of MI. As such, the degree of cardiac injury and cardiac impairment observed in HyCHDL-infused animals is comparable to that observed in vehicle-infused animals. These observations suggest that the presence of comorbidities may alter HDL’s beneficial properties. Particularly noteworthy, in contrast to primary prevention, the association between HDL cholesterol and cardiovascular events is altered in patients with established CVD (4), and HDL-raising therapies in CVD patients have yielded disappointing results (5). Further studies are warranted to fully characterize HDL functionality and structural remodeling in different clinical conditions.
Please note: This work was supported by grants from the Ministry of Science and Education of Spain (SAF2012-40208 to Dr. Vilahur and SAF2013-42962-R to Dr. Badimon), and from Instituto de Salud Carlos III (RIC-RD12/0042/0027 and TERCEL RD12/0019/0026 to Dr. Badimon). All grants were co-financed by European Union Funds, Fondo Europeo de Desarrollo Regional (FEDER) “Una manera de hacer Europa.” This work was also supported by a grant from the Spanish Society of Cardiology (FEC 2012 to Dr. Vilahur) and a grant from the Muy Ilustrísima Administración from the Hospital de la Santa Creu I Sant Pau (to Dr. Gutiérrez). All authors have reported that they have no relationships relevant to the contents of this paper to disclose. The authors thank Fundación Jesús Serra, Barcelona, for continuous support.
- 2015 American College of Cardiology Foundation