Journals | Policy | Permission

Journal of Clinical Medicine Research

Original Article

Volume 11, Number 10, October 2019, pages 676-681

Ezetimibe Monotherapy Reduces Serum Levels of Platelet-Activating Factor Acetylhydrolase in Patients With Dyslipidemia

Dyslipidemia causes cardiovascular disease (CVD) due to atherosclerosis of the arterial vessel wall, and is the foremost cause of premature mortality and disability-adjusted life years [1]. Ezetimibe selectively inhibits the intestinal absorption of cholesterol and related phytosterols. In the IMPROVE-IT study, the combination of ezetimibe plus simvastatin therapy in patients with post-acute coronary syndrome significantly reduced cardiovascular events compared to simvastatin monotherapy [2].

Ezetimibe monotherapy has been shown to reduce atherothrombotic complications after superficial plaque erosion [3] and to attenuate atherosclerosis associated with lipid reduction and the inhibition of inflammation [4]. We previously reported that ezetimibe monotherapy for dyslipidemia patients reduced the serum levels of total cholesterol (T-chol), low-density lipoprotein cholesterol (LDL-chol), and non-high-density lipoprotein cholesterol (non-HDL-chol), especially in metabolic syndrome (MetS) (Zenith Trial) [5]. But ezetimibe is not recommended as a fist choice for dyslipidemia.

Platelet-activating factor acetylhydrolase (PAF-AH) activity is a circulating enzymatic biomarker of inflammation that is primarily bound to LDL-chol [6]. We previously reported that PAF-AH activity was associated with paroxysmal atrial fibrillation [6] and HDL-associated PAF-AH activity was associated with diabetes mellitus (DM) and the coronary artery calcification score [7]. PAF-AH activity was also associated with both unstable and stable coronary heart disease [8] and was an independent predictor of coronary artery disease (CAD) [9].

HDL-chol efflux capacity (HDL-CEC), one of the functions of HDL-chol, has a strong inverse association with atherosclerosis [10]. We previously reported the efficacy of HDL-CEC against atherosclerosis and CAD [11-15].

In this study, we investigated PAF-AH and HDL-CEC in dyslipidemia patients receiving ezetimibe monotherapy.

Kumagai et al previously reported the effects of ezetimibe on dyslipidemia patients with MetS (Zenith Trial) [5]. Each subject signed an informed consent form after the protocol was explained. Patients who were treated with ezetimibe for dyslipidemia from January 2009 to August 2011 at Fukuoka University Hospital and its related hospitals in the Kyushu area of Japan were enrolled. Patients who were pretreated with statin after a 4-week washout period were enrolled. Serum samples were collected at baseline and after 16 weeks of treatment with ezetimibe. The patients were divided into MetS and non-MetS groups. Male, the presence of MetS, and a lower ratio of LDL-chol to HDL-chol were independent factors that predicted a good response to ezetimibe monotherapy. For this investigation, the Zenith Trial including the current investigation was approved by the Independent Review Board (IRB) of Fukuoka University (2017M160) and conducted according to the Declaration of Helsinki regarding investigations in humans. We excluded 16 patients from the Zenith Trial due to insufficient blood sample volumes, and finally analyzed 42 patients.

Serum lipoprotein-associated phospholipase A2 was measured by a spectrophotometric assay using an automatic analyzer (JCA-BM6010, JEOL, Ltd, Tokyo, Japan) [16]. HDL-associated PAF-AH (HDL-PAF-AH) activity was measured in apolipoprotein B-depleted serum, which was separated by precipitation of apo-B using phosphotungstate acid/MgCl₂. The value of LDL-associated PAF-AH (LDL-PAF-AH) activity was taken to be the value of PAF-AH activity in whole serum minus the value of HDL-PAF-AH activity, as previously described [6, 7].

HDL-CEC was measured by an ex vivo technique, as previously described [11-15]. 3H-cholesterol-labeled J774 macrophage cells were incubated with apoB-depleted serum samples for 4 h. Radiolabeled cholesterol counts in macrophage and medium were measured by a liquid scintillation analyzer (Tri-Carb 2900TR, Perkin Elmer Co., Ltd, MA, USA). HDL-CEC was calculated as HDL-CEC (%) = (radioactivity in the medium/radioactivity in the medium + macrophages) × 100/cholesterol efflux activity in serum-free medium.

Age, gender, body mass index (BMI), history of hypertension (HT), DM, and CAD were evaluated. BMI was calculated as weight (kg)/height² (m²).

Serum levels of white blood cell (WBC), high-sensitivity C-reactive protein (hs-CRP), blood urea nitrogen (BUN), creatinine (Cr), aspartate aminotransferase (AST), alkaline phosphatase (ALT), T-chol, TG, LDL-chol, HDL-chol, remnant-like particle-cholesterol (RLP-chol), and adiponectin were evaluated at the Fukuoka University Hospital Laboratory Unit or by SRL Corporation, as reported previously [5].

All data analyses were performed using the SAS (Statistical Analysis System) Software Package (Ver. 9.4, SAS Institute Inc., Cary, NC, USA) at Fukuoka University (Fukuoka, Japan). Continuous variables with a normal distribution were expressed as mean ± standard deviation and compared between groups by Student’s t-test. Continuous variables with a non-normal distribution were expressed as median (interquartile range) and compared between groups by the Wilcoxon rank sum test. Categorical variables were compared between groups by a Chi-square analysis. The baseline laboratory data and the data after 16 weeks of treatment were compared by the paired t-test for continuous variables with a normal distribution and by the Wilcoxon signed rank test for continuous variables with a non-normal distribution. A value of P < 0.05 was considered significant.

Table 1 shows the patient characteristics. In all patients, average age, BMI, and the percentages of male, HT, DM, and CAD were 61.0 ± 8.8 years, 26.3 ± 3.4 kg/m², 59.5% (n = 25), 87.8% (n = 36), 57.1% (n = 24), and 11.9% (n = 5), respectively. The percentage of DM in the MetS group was significantly greater than that in non-MetS group (MetS group: 77.3% vs. non-MetS group: 35.0%, P = 0.006).

Click to view

Table 1. Patient Characteristics

Laboratory data at baseline and after 16 weeks of treatment with ezetimibe are shown in Table 2. At baseline, TG and RLP-chol in the MetS group were significantly higher than those in the non-MetS group (TG: 178 ± 61 mg/dL vs. 120 ± 64 mg/dL, P = 0.004 and RLP-chol: 7.4 (6.8 - 9.1) mg/dL vs. 4.6 (3.7 - 5.5) mg/dL, P = 0.0002). T-chol, HDL-chol, LDL-chol, and adiponectin in the MetS group were not significantly different than those in the non-MetS group. T-chol and LDL-chol were significantly decreased during 16 weeks of treatment with ezetimibe in all patients (T-chol: baseline 242 ± 33 mg/dL, 16 weeks of treatment: 208 (191 - 223) mg/dL, P < 0.0001; and LDL-chol: 165 ± 29 mg/dL, 127 (113 - 144) mg/dL, P < 0.0001) and in both the MetS (T-chol: 249 ± 35 mg/dL, 213 ± 39 mg/dL, P < 0.0001 and LDL-chol: 171 ± 30 mg/dL, 134 ± 31 mg/dL, P < 0.0001) and non-MetS (T-chol: 234 ± 29 mg/dL, 210 ± 21 mg/dL, P < 0.0001 and LDL-chol: 158 ± 26 mg/dL, 132 ± 24 mg/dL, P < 0.0001) groups. RLP-chol was significantly decreased after 16 weeks of treatment with ezetimibe in all patients (6.4 (4.4 - 7.8) mg/dL, 4.8 (4.0 - 6.9) mg/dL, P = 0.003) and the MetS group (7.4 (6.8 - 9.1) mg/dL, 6.5 ± 2.5 mg/dL, P < 0.0001), but not the non-MetS group (4.6 (3.7 - 5.5) mg/dL, 4.5 ± 1.4 mg/dL, P = 0.1). After 16 weeks of treatment with ezetimibe, TG and RLP-chol in the MetS group were still significantly higher than those in the non-MetS group (TG: 166 ± 51 mg/dL vs. 118 (96 - 129) mg/dL, P = 0.01 and RLP-chol: 6.5 ± 2.5 mg/dL vs. 4.5 ± 1.4 mg/dL, P = 0.01).

Click to view

Table 2. Laboratory Data on Pre- and Post-Treatment With Ezetimibe for 16 Weeks

Data regarding PAF-AH and HDL-CEC are shown in Figure 1. There were no significant differences between the MetS and non-MetS groups at baseline. PAF-AH and LDL-PAF-AH were significantly decreased after 16 weeks of treatment with ezetimibe in all patients (PAF-AH: 521 ± 164 U/L, 450 ± 155 U/L, P < 0.0001 and LDL-PAF-AH: 499 ± 163 U/L, 428 ± 154 U/L, P < 0.0001) and in both the MetS (PAF-AH: 506 ± 108 U/L, 431 ± 119 U/L, P < 0.0001 and LDL-PAF-AH: 514 ± 109 U/L, 450 ± 119 U/L, P < 0.0001), and non-MetS (PAF-AH: 537 ± 203 U/L, 473 ± 180 U/L, P < 0.0001 and LDL-PAF-AH: 486 ± 202 U/L, 411 ± 178 U/L, P < 0.0001) groups. HDL-PAF-AH and HDL-CEC were not significantly changed by 16 weeks of treatment in either of all patients, the MetS group, or the non-MetS group.

Click for large image

Figure 1. Platelet-activating factor acetylhydrolase activity and high-density lipoprotein cholesterol efflux capacity. PAF-AH (a), HDL-PAF-AH (b), LDL-PAF-AH activity (c) and HDL-CEC (d) at baseline and after 16 weeks of treatment in all patients and in the MetS and non-MetS groups. PAF-AH: platelet-activating factor acetylhydrolase; HDL-PAF-AH: high-density lipoprotein-associated PAF-AH; LDL-PAF-AH: low-density lipoprotein-associated PAF-AH; HDL-CEC: high-density lipoprotein cholesterol efflux capacity; MetS: metabolic syndrome. *P < 0.05.

We investigated the effects of ezetimibe monotherapy for PAF-AH and HDL-CEC in patients with dyslipidemia. Ezetimibe significantly reduced PAF-AH and LDL-PAF-AH in addition to reducing T-chol and LDL-chol regardless of the presence or absence of MetS, and did not change the levels of HDL-PAF-AH and HDL-CEC.

Ezetimibe improved T-chol and LDL-chol in all patients and in both the MetS and non-MetS groups. These are reasonable effects of ezetimibe due to the selective inhibition of intestinal absorption of cholesterol. Ezetimibe also improved RLP-chol in all patients and the MetS group, but not the non-MetS group, because the level of RLP-chol in the non-MetS group was within the normal range at baseline. The incidence of diabetes in the MetS group was significantly higher than that in the non-MetS group, because diabetes is one of the diagnostic criteria of MetS [17].

Packard et al reported that inflammatory markers, especially PAF-AH, are predictors of coronary events [9]. Tsimikas et al reported that an increased PAF-AH level was associated with MetS, and the incidences of both fatal and non-fatal CVD [18]. In this study, ezetimibe significantly reduced PAF-AH in both the MetS and non-MetS groups. Ezetimibe selectively inhibits the intestinal absorption of cholesterol and decreases serum LDL-chol. Since PAF-AH is reportedly strongly influenced by LDL-chol [18], it is possible that ezetimibe significantly reduced PAF-AF due to its effect of lowering LDL-chol. These results indicate that ezetimibe monotherapy may have a potential role in suppressing CVD regardless of the presence or absence of MetS. We previously reported the efficacies of HDL-PAF-AH and LDL-PAF-AH [6, 7]. In this study, HDL-PAF-AH was not significantly improved after 16 weeks of treatment with ezetimibe monotherapy because almost no PAF-AH was detected in apoB-depleted serum (LDL-PAF-AH). In this study, isolation of PAF-AH into HDL- and LDL-PAF-AH might be unrelated to the efficacy of ezetimibe monotherapy.

HDL-CEC is one of the effects of HDL-chol against atherosclerosis [10]. In this study, ezetimibe monotherapy was expected to improve HDL-CEC, since previous reports demonstrated that ezetimibe affects reverse cholesterol transport [19, 20]. On the other hand, it was reported that treatment with a combination of atorvastatin plus ezetimibe did not increase HDL-CEC [21, 22]. Ezetimibe monotherapy did not improve HDL-CEC in this study. Although we previously reported that total CEC was positively correlated with HDL-chol levels [12], ezetimibe monotherapy did not change the levels of HDL-chol in this study. Taken together the results of PAF-AH, ezetimibe monotherapy had an effect for LDL-chol-associated factors rather than HDL-chol-associated factors.

This study has several limitations. For example, a sufficient sample size was needed for several investigations. Although we discontinued statin treatment with a 4-week washout period before enrollment, statins may exert a legacy effect for CVD [23]. Ezetimibe monotherapy decreased levels of both LDL-chol and LDL-PAF-AH, and delta LDL-chol was significantly associated with changes in LDL-PAF-AH (data not shown). The reduction of LDL-PAF-AH might be due to the reduction of LDL-chol. We can expect that ezetimibe monotherapy would have an atheroprotective effect in addition to an LDL-chol-lowering effect, since PAF-AH has been shown to be an independent predictor of atherosclerosis regardless of the lipid profile [9].

In conclusion, ezetimibe significantly reduced PAF-AH in addition to reducing T-chol and LDL-chol regardless of the presence or absence of MetS.

Acknowledgments

None to declare.

Financial Disclosure

None to declare.

Conflict of Interest

None to declare.

Informed Consent

In the Zenith Trial, each subject signed an informed consent form after the protocol was explained. For this investigation, the Zenith Trial including the current investigation was approved by the Independent Review Board (IRB) of Fukuoka University (2017M160). In current investigation, there was no informed consent because the current investigation was a retrospective study.

Author Contributions

Acquisition: YS, K. Tano and NKK; conception and design: YS and SM; analysis: K. Tano, YM, YS and NKK; interpretation: K. Tashiro, TK and SM.

1. Catapano AL, Graham I, De Backer G, Wiklund O, Chapman MJ, Drexel H, Hoes AW, et al. 2016 ESC/EAS guidelines for the management of dyslipidaemias. Eur Heart J. 2016;37(39):2999-3058.
   doi pubmed
2. Murphy SA, Cannon CP, Blazing MA, Giugliano RP, White JA, Lokhnygina Y, Reist C, et al. Reduction in Total Cardiovascular Events With Ezetimibe/Simvastatin Post-Acute Coronary Syndrome: The IMPROVE-IT Trial. J Am Coll Cardiol. 2016;67(4):353-361.
   doi pubmed
3. Honda K, Matoba T, Antoku Y, Koga JI, Ichi I, Nakano K, Tsutsui H, et al. Lipid-Lowering therapy with ezetimibe decreases spontaneous atherothrombotic occlusions in a rabbit model of plaque erosion: a role of serum oxysterols. Arterioscler Thromb Vasc Biol. 2018;38(4):757-771.
   doi pubmed
4. Tie C, Gao K, Zhang N, Zhang S, Shen J, Xie X, Wang JA. Ezetimibe attenuates atherosclerosis associated with lipid reduction and inflammation inhibition. PLoS One. 2015;10(11):e0142430.
   doi pubmed
5. Naoko Kumagai S-iM, Bo Zhang, Keita Noda, Keijiro Saku, Zenith Trial Investigators. Effects of ezetimibe on hypercholesterolemia in the lipid profile in patients with metabolic syndrome: Zenith Trial. IJC Metabolic & Endocrine. 2013;1:7-12.
   doi
6. Okamura K, Miura S, Zhang B, Uehara Y, Matsuo K, Kumagai K, Saku K. Ratio of LDL- to HDL-associated platelet-activating factor acetylhydrolase may be a marker of inflammation in patients with paroxysmal atrial fibrillation. Circ J. 2007;71(2):214-219.
   doi pubmed
7. Mitsutake R, Miura S, Zhang B, Saku K. HDL-associated factors provide additional prognostic information for coronary artery disease as determined by multi-detector row computed tomography. Int J Cardiol. 2010;143(1):72-78.
   doi pubmed
8. Samsamshariat S, Basati G, Movahedian A, Pourfarzam M, Sarrafzadegan N. Elevated plasma platelet-activating factor acetylhydrolase activity and its relationship to the presence of coronary artery disease. J Res Med Sci. 2011;16(5):674-679.
   doi pubmed
9. Packard CJ, O'Reilly DS, Caslake MJ, McMahon AD, Ford I, Cooney J, Macphee CH, et al. Lipoprotein-associated phospholipase A2 as an independent predictor of coronary heart disease. West of Scotland Coronary Prevention Study Group. N Engl J Med. 2000;343(16):1148-1155.
   doi pubmed
10. Khera AV, Cuchel M, de la Llera-Moya M, Rodrigues A, Burke MF, Jafri K, French BC, et al. Cholesterol efflux capacity, high-density lipoprotein function, and atherosclerosis. N Engl J Med. 2011;364(2):127-135.
    doi pubmed
11. Imaizumi S, Miura S, Takata K, Takamiya Y, Kuwano T, Sugihara M, Ike A, et al. Association between cholesterol efflux capacity and coronary restenosis after successful stent implantation. Heart Vessels. 2016;31(8):1257-1265.
    doi pubmed
12. Norimatsu K, Kuwano T, Miura SI, Shimizu T, Shiga Y, Suematsu Y, Miyase Y, et al. Significance of the percentage of cholesterol efflux capacity and total cholesterol efflux capacity in patients with or without coronary artery disease. Heart Vessels. 2017;32(1):30-38.
    doi pubmed
13. Shimizu T, Miura S, Tanigawa H, Kuwano T, Zhang B, Uehara Y, Saku K. Rosuvastatin activates ATP-binding cassette transporter A1-dependent efflux ex vivo and promotes reverse cholesterol transport in macrophage cells in mice fed a high-fat diet. Arterioscler Thromb Vasc Biol. 2014;34(10):2246-2253.
    doi pubmed
14. Takata K, Imaizumi S, Kawachi E, Suematsu Y, Shimizu T, Abe S, Matsuo Y, et al. Impact of cigarette smoking cessation on high-density lipoprotein functionality. Circ J. 2014;78(12):2955-2962.
    doi pubmed
15. Uehara Y, Ando S, Yahiro E, Oniki K, Ayaori M, Abe S, Kawachi E, et al. FAMP, a novel apoA-I mimetic peptide, suppresses aortic plaque formation through promotion of biological HDL function in ApoE-deficient mice. J Am Heart Assoc. 2013;2(3):e000048.
    doi pubmed
16. Kosaka T, Yamaguchi M, Soda Y, Kishimoto T, Tago A, Toyosato M, Mizuno K. Spectrophotometric assay for serum platelet-activating factor acetylhydrolase activity. Clin Chim Acta. 2000;296(1-2):151-161.
    doi
17. Despres JP, Lemieux I. Abdominal obesity and metabolic syndrome. Nature. 2006;444(7121):881-887.
    doi pubmed
18. Tsimikas S, Willeit J, Knoflach M, Mayr M, Egger G, Notdurfter M, Witztum JL, et al. Lipoprotein-associated phospholipase A2 activity, ferritin levels, metabolic syndrome, and 10-year cardiovascular and non-cardiovascular mortality: results from the Bruneck study. Eur Heart J. 2009;30(1):107-115.
    doi pubmed
19. Briand F, Naik SU, Fuki I, Millar JS, Macphee C, Walker M, Billheimer J, et al. Both the peroxisome proliferator-activated receptor delta agonist, GW0742, and ezetimibe promote reverse cholesterol transport in mice by reducing intestinal reabsorption of HDL-derived cholesterol. Clin Transl Sci. 2009;2(2):127-133.
    doi pubmed
20. Davidson MH, Voogt J, Luchoomun J, Decaris J, Killion S, Boban D, Glass A, et al. Inhibition of intestinal cholesterol absorption with ezetimibe increases components of reverse cholesterol transport in humans. Atherosclerosis. 2013;230(2):322-329.
    doi pubmed
21. Nicholls SJ, Ray KK, Ballantyne CM, Beacham LA, Miller DL, Ruotolo G, Nissen SE, et al. Comparative effects of cholesteryl ester transfer protein inhibition, statin or ezetimibe on lipid factors: The ACCENTUATE trial. Atherosclerosis. 2017;261:12-18.
    doi pubmed
22. Lee CJ, Choi S, Cheon DH, Kim KY, Cheon EJ, Ann SJ, Noh HM, et al. Effect of two lipid-lowering strategies on high-density lipoprotein function and some HDL-related proteins: a randomized clinical trial. Lipids Health Dis. 2017;16(1):49.
    doi pubmed
23. Kashef MA, Giugliano G. Legacy effect of statins: 20-year follow up of the West of Scotland Coronary Prevention Study (WOSCOPS). Glob Cardiol Sci Pract. 2016;2016(4):e201635.
    doi pubmed

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial 4.0 International License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Journal of Clinical Medicine Research is published by Elmer Press Inc.