Serum sdLDL-C and Cellular SREBP2-dependent Cholesterol Levels; is there a Challenge on Targeting PCSK9?

Efficacy and Safety of Alirocumab and Evolocumab as Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Inhibitors in Familial Hypercholesterolemia: A Systematic Review and Meta-Analysis

BACKGROUND

Familial hypercholesterolemia (FH) is a prevalent and potentially fatal illness that causes a substantial elevation in low-density lipoprotein cholesterol (LDL-C).

OBJECTIVE

The aim of this study was to investigate the effects of monoclonal antibodies alirocumab and evolocumab on LDL-C and other lipid parameters, as well as their safety in familial hypercholesterolemia patients.

METHODS

A comprehensive search was done on PubMed/MEDLINE, EMBASE, Web of Science (WOS/ ISI), Scopus, ClinicalTrials (www.

CLINICALTRIALS

gov), and conferences/ congress research papers. Random effect models were used to calculate mean differences (%) and risk ratios (RRs), and confidence intervals (95%).

RESULTS

Ten studies (n=1489 patients) were included in this study. PCSK9 inhibitors decreased the levels of LDL-C by -49.59% (95%CI -55.5%, -43.67%) as compared to placebo. They also didn't alter the Treatment-Emergent Adverse Event (TEAE) and neuronal events by RR 0.92 (0.75, 1.13) and 1.31 (0.66, 2.59), respectively. PCSK9 inhibitors were effective and safe in treating patients with FH.

CONCLUSION

There was high-quality evidence showing that monoclonal antibodies (alirocumab & evolocumab) lower LDL-C (GRADE: high), lipoprotein (a) (GRADE: High), triglycerides (TG) (GRADE: High), total cholesterol (GRADE: High), non-high-density lipoprotein cholesterol (non- HDL-C) (GRADE: Moderate), and apolipoprotein B (GRADE: High), and increase the HDL-C (GRADE: High) as well as apolipoprotein A1 (GRADE: High). Comparing PCSK9 inhibitors against placebo, neither TEAE (GRADE: high) nor neuronal events (GRADE: moderate) were changed.

Serum and genetic markers related to rapid clinical progression of coronary artery disease

INTRODUCTION AND OBJECTIVES

Patients with clinically evident coronary artery disease differ in their rate of progression, which impacts prognosis. We aimed to characterize serum and genetic markers in patients with rapid clinical progression (RCP) of coronary artery disease vs those with long standing stable (LSS) disease.

METHODS

Retrospective study of cases (RCP) and controls (LSS) (1:2). Patients requiring ≥ 2 revascularizations due to atherosclerotic progression in the 10 years after a first angioplasty were considered to be RCP and those without events during the same period after the first angioplasty were considered to have LSS disease. After patient selection, we analyzed serum values, mRNA expression and genetic polymorphisms of inflammatory markers, including interleukin-6, C-reactive protein, and tumor necrosis factor (TNF)-a, and atherogenic markers consisted of proprotein convertase subtilisin/kexin type 9 (PCSK9), low-density lipoprotein receptor, sterol regulatory element binding transcription factor 2, and apolipoprotein-B.

RESULTS

The study included 180 patients (58 RCP and 122 LSS). Demographic characteristics, classic risk factors and the extent of coronary disease were similar in the 2 groups. Patients with RCP showed higher serum levels of interleukin-6 and PCSK9 and higher TNF mRNA expression. Interleukin-6 rs180075C, TNF rs3093664 non-G and PCSK9 rs2483205 T alleles conferred a risk of RCP (P<.05 in all cases). Among patients with RCP, 51.7% had all 3 risk alleles vs 18% of those with LSS (P<.001).

CONCLUSIONS

We suggest the existence of specific phenotypic and genotypic markers associated with RCP of coronary artery disease that could help to individualize the type and intensity of treatment.

Elevated Serum Small Dense Low-Density Lipoprotein Cholesterol May Increase the Risk and Severity of Coronary Heart Disease and Predict Cardiovascular Events in Patients with Type 2 Diabetes Mellitus

Background

Coronary heart disease (CHD) is a common and severe complication in type 2 diabetes mellitus (T2DM) patients. Increased amount of circulatory small dense low-density lipoprotein cholesterol (sdLDL-C) particles is known to be a sign of dyslipidemia and can result in atherosclerosis. However, the association between serum sdLDL-C levels and CHD in T2DM patients remains unclear.

Methods

A total of 3684 T2DM patients who received selective coronary angiography (CAG) were selected. For analyzing the association between sdLDL-C and CHD severity in T2DM, the patients with CHD were further divided into four subgroups according to the quartiles of sdLDL-C. A multivariate logistic regression was used for analyzing the risks and severity of CHD. A total of 3427 patients with continuous stable CHD were recruited and followed up for 5 years.

Results

Serum sdLDL-C levels in the CHD group were significantly increased compared with those in the non-CHD group [0.80 (0.49) mmol/L vs. 0.70 (0.30) mmol/L, p < 0.001]. The results from CHD subgroup analysis indicated that the sdLDL-C levels in patients with multiple-vessel disease and high Gensini score (GS) were significantly increased. By adjusting the confounding factors and analyzing with multiple logistic regression, we found that sdLDL-C independently correlated with the presence and severity of CHD (CHD: OR = 2.257; multiple-vessel disease: OR = 3.288; high GS: OR = 2.554). A total of 484 major cardiovascular events (MACEs) were documented. After Kaplan-Meier analysis and chi-squared analysis, the incidence of MACEs in the high sdLDL-C group was higher than that in the low sdLDL-C group (16.04% vs. 12.25%, p = 0.002).

Conclusion

In T2DM patients, elevated serum sdLDL-C may increase the severity of CHD and predict cardiovascular events in the future. Therefore, serum sdLDL-C may be a potential biomarker for the surveillance of CHD in T2DM patients.

Comparative Effects of Curcumin versus Nano-Curcumin on Insulin Resistance, Serum Levels of Apelin and Lipid Profile in Type 2 Diabetic Rats

BACKGROUND AND PURPOSE

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and abnormalities in insulin production. Apelin is associated with insulin resistance. According to the anti-diabetic properties of curcumin, the purpose of this study was to compare the effects of curcumin and nano-curcumin intake on insulin resistance and serum levels of fasting blood sugar (FBS), Apelin, and lipid profile (cholesterol, triglyceride, LDL, HDL and VLDL) in T2DM rats.

MATERIALS AND METHODS

Forty-eight male Wistar rats were divided into six groups: Control, diabetic, diabetic treated with two doses of curcumin (100 and 200 mg/kg) and diabetic treated with two doses of nano-curcumin (100 and 200 mg/kg). Induction of T2DM was performed by intraperitoneal injection of Nicotinamide (110 mg/kg) and Streptozotocin (45 mg/kg) in the fasting state. Rats received different doses of nano-curcumin and curcumin by gavage (daily) for 28 days. At the end of the intervention period, insulin resistance and serum levels of FBS, apelin and lipid profiles were measured.

RESULTS

Insulin resistance and serum levels of FBS, Apelin, cholesterol, triglycerides, LDL, and VLDL were significantly decreased in diabetic rats treated with curcumin and nano-curcumin (p<0.05) so that nano-curcumin in reducing lipid profile is more effective than curcumin (P<0.05). Serum level of HDL in nano-curcumin groups was significantly higher than diabetic and curcumin groups (p<0.05). Also, with increasing insulin resistance, serum level of apelin increased (P<0.05).

CONCLUSION

The therapeutic effects of curcumin and nano-curcumin were effective in decreasing insulin resistance, serum levels of FBS, apelin and lipid profile. The dose of 100 mg/kg nano-curcumin was more effective in reducing lipid profile.

Structure and Function of Proprotein Convertase Subtilisin/kexin Type 9 (PCSK9) in Hyperlipidemia and Atherosclerosis

Background:

One of the important factors in Low-Density Lipoprotein (LDL) metabolism is the LDL receptor (LDLR) by its capacity to bind and subsequently clear cholesterol derived from LDL (LDL-C) in the circulation. Proprotein Convertase Subtilisin-like Kexin type 9 (PCSK9) is a newly discovered serine protease that destroys LDLR in the liver and thereby controls the levels of LDL in plasma. Inhibition of PCSK9-mediated degradation of LDLR has, therefore, become a novel target for lipid-lowering therapy.

Methods:

We review the current understanding of the structure and function of PCSK9 as well as its implications for the treatment of hyperlipidemia and atherosclerosis.

Results:

New treatments such as monoclonal antibodies against PCSK9 may be useful agents to lower plasma levels of LDL and hence prevent atherosclerosis.

Conclusion:

PCSK9's mechanism of action is not yet fully clarified. However, treatments that target PCSK9 have shown striking early efficacy and promise to improve the lives of countless patients with hyperlipidemia and atherosclerosis.

Association Between Fat-soluble Vitamins and Lipid Profile in the Overweight Population

BACKGROUND & AIMS

It is well-known that the coronary artery stenosis is related to lipid profile. This is a descriptive cross-sectional study to investigate the relationship between the serum fat-soluble vitamins (A, E and D), circulating proprotein convertase subtilisin/kexin type 9 (PCSK9), and lipid profile in the study population.

METHODS

A total of 120 overweight subjects were participated in this study. The circulating PCSK9 and vitamin D were measured by ELISA technique. The serum vitamin A and vitamin E amounts were simultaneously measured by the HPLC method. The Serum Small Dense LDLCholesterol (sdLDL-C) values were evaluated using heparin-Mg2+ precipitation technique. The lipid profile was measured by routine laboratory techniques.

RESULTS

The serum vitamin E values correlated significantly to vitamin A (r= 0.47, P= 0.0001), VLDL-C (r= 0.30, P= 0.002), total cholesterol (r= 0.309, P= 0.001), PCSK9 (r= 0.233, P= 0.01) and total triglyceride (r= 0.61, P= 0.0001) values. The circulating PCSK9 values correlated significantly to LDL-C (r= 0.17, P= 0.05) and total cholesterol (r= 0.23, P= 0.009) values. However, there were not correlations between the levels of serum D and A vitamins, the serum LDL-C, sdLDL-C and total cholesterol values.

CONCLUSION

The data showed the correlations between serum vitamin E and PCSK9-related LDLC values lower than the normal range. Furthermore, the results suggested a nutritional need on the patents considering supplementation or fortification of vitamin E for the overweight subjects with higher LDL-C levels.

PCSK9 positively correlates with plasma sdLDL in community-dwelling population but not in diabetic participants after confounder adjustment

This study aimed to investigate the relationship between plasma proprotein convertase subtilisin kexin 9 (PCSK9) and small dense low-density lipoprptein (sdLDL) in diabetic and non-diabetic participants in a community-dwelling cohort.The plasma levels of PCSK9 and sdLDL were detected in 1766 participants (median age: 61.40 years; 733 males vs 1033 females; 383 diabetic vs 1383 non-diabetic patients) from the Pingguoyuan community of Beijing, China.Results showed that Pearson correlation analysis revealed a positive correlation between PCSK9 and sdLDL (r = 0.263, P < .001). Multiple linear regression analysis showed a significant positive correlation between plasma PCSK9 and sdLDL in the whole population study. sdLDL was used as the dependent variable, and the potential cofounders were adjusted. However, any independent relationship was not observed between circulating PCSK9 and sdLDL in the diabetic subpopulation (r = 0.269, P < .05, β = 9.591, P > .05).Thus, there is a positive correlation between plasma PCSK9 and sdLDL in a community-dwelling cohort, but not in type 2 diabetic subpopulation, after confounder adjustment.

THE EFFECT OF MELATONIN AGAINST GASTRIC OXIDATIVE STRESS AND DYSLIPIDEMIA IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

OBJECTIVE

The aim of this study was to evaluate the possible protective effects of MT against gastric oxidative stress and dyslipidemia in streptozotocin (STZ) - induced diabetic rats.

METHODS

Forty male Wistar rats were randomly divided into five groups: control, diabetic, MT 5 mg/kg+ STZ, MT 10 mg/kg+ STZ and MT 20 mg/kg+ STZ. STZ (60 mg/kg) was intraperitoneally (ip) injected as a single dose for diabetes induction. One week after STZ administration, MT was injected daily as ip for 14 days. The levels of malondialdehyde (MDA), total thiol and glutathione, as well as superoxide dismutase (SOD) and catalase activities were measured in gastric tissue. Serum concentrations of triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL) were also determined.

RESULTS

Serum glucose significantly increased in diabetic group compared to control group. STZ induced a significant decrease in gastric tissue levels of total thiol, glutathione, catalase and SOD activities and a significant increase in MDA concentration. In diabetic rats, serum TG, LDL and TC were significantly higher and HDL was significantly lower than in the control group. Treatment of diabetic rats with MT caused a significant increase in gastric total thiol content and glutathione concentration as well as SOD and catalase activities. Gastric MDA concentration and serum LDL, TG and TC were significantly lower in MT-treated groups when compared with diabetic group.

CONCLUSION

These data suggested that MT has a therapeutic effect on gastric oxidative damage and dyslipidemia induced by diabetes that possibly may be due to its antioxidant effects.

Circulating low density lipoprotein (LDL)

Low-density lipoprotein (LDL) particles are known as atherogenic agents in coronary artery diseases. They modify to other electronegative forms and may be the subject for improvement of inflammatory events in vessel subendothelial spaces. The circulating LDL value is associated with the plasma PCSK-9 level. They internalize into macrophages using the lysosomal receptor-mediated pathways. LDL uptake is related to the membrane scavenger receptors, modifications of lipid and protein components of LDL particles, vesicular maturation and lipid stores of cells. Furthermore, LDL vesicular trafficking is involved with the function of some proteins such as Rab and Lamp families. These proteins also help in the transportation of free cholesterol from lysosome into the cytosol. The aggregation of lipids in the cytosol is a starting point for the formation of foam cells so that they may participate in the primary core of atherosclerosis plaques. The effects of macrophage subclasses are different in the formation and remodeling of plaques. This review is focused on the cellular and molecular events involved in cholesterol homeostasis.

Interleukin 6 may be related to indoleamine 2,3-dioxygense function in M2 macrophages treated with small dense LDL particles

Macrophages are known as important immune cells involved in the improvement of atherosclerosis plaques. The M2 macrophages are beneficial because scavenging the non-functional components in vessel sub-endothelial space. In this study, we investigated the effects of small dense LDL (sdLDL) on the changes of indoleamine 2,3-dioxygense (IDO) and interleukin (IL6) in the differentiated M2 macrophages. The patients were selected from who underwent coronary artery angiography. The monocytes were isolated from the whole blood samples of healthy (<5% stenosis) and patient (>70% stenosis; SVD, 2VD and 3VD) subjects and, were differentiated into M2 macrophages. The IDO gene expression, activity and IL6 values were measured by RT-qPCR, colorimetry and ELISA techniques, respectively. In contrast with healthy group, the IDO gene expression and activity were significantly reduced in SVD and 2VD groups (P<0.05). Furthermore, they were conversely associated to secretion of IL6. In conclusion, the data suggested that inflammatory responses in M2 macrophages differentiated from monocytes of patients after treatment of sdLDL may be related to the reduced IDO function.