Small dense low-density lipoprotein cholesterol is a useful marker of metabolic syndrome in patients with coronary artery disease

Clinical significance of small dense low-density lipoprotein cholesterol measurement in type 2 diabetes

Low-density lipoprotein cholesterol (LDL-C) is known to be a causal substance of atherosclerosis, but its usefulness as a predictive biomarker for atherosclerotic cardiovascular disease (ASCVD) is limited. In patients with type 2 diabetes (T2D), LDL-C concentrations do not markedly increase, while triglycerides (TG) concentrations are usually elevated. Although TG is associated with ASCVD risk, they do not play a direct role in the formation of atheromatous plaques. TG changes the risk of ASCVD in a way that is dependent on LDL-C, and TG is the primary factor in reducing LDL particle size. Small dense (sd)LDL, a potent atherogenic LDL subfraction, best explains the "Atherogenic Duo" of TG and LDL-C. Although hypertriglyceridemia is associated with small-sized LDL, patients with severe hypertriglyceridemia and low LDL-C rarely develop ASCVD. This suggests that quantifying sdLDL is more clinically relevant than measuring LDL size. We developed a full-automated direct sdLDL-C assay, and it was proven that sdLDL-C is a better predictor of ASCVD than LDL-C. The sdLDL-C level is specifically elevated in patients with metabolic syndrome and T2D who have insulin resistance. Due to its clear link to metabolic dysfunction, sdLDL-C could be named "metabolic LDL-C." Insulin resistance/hyperinsulinemia promotes TG production in the liver, causing steatosis and overproduction of VLDL1, a precursor of sdLDL. sdLDL-C is closely associated with steatotic liver disease and chronic kidney disease, which are common complications in T2D. This review focuses on T2D and discusses the clinical significance of sdLDL-C including its composition, pathophysiology, measurements, association with ASCVD, and treatments.

Specific Increase in Small Dense Low-Density Lipoprotein-Cholesterol Levels beyond Triglycerides in Patients with Diabetes: Implications for Cardiovascular Risk of MAFLD

AIMS

Small dense (sd) low-density lipoprotein (LDL)-cholesterol (C) is the most powerful predictor of cardiovascular (CV) disease among lipid biomarkers and is generated by hypertriglyceridemia and insulin resistance. Metabolic dysfunction-associated fatty liver disease (MAFLD) is a newly proposed liver disease with a high CV risk. We investigated the specific association of sdLDL-C with MAFLD beyond triglycerides (TG) and obesityMethods: Participants were 839 non-alcoholic drinkers with type 2 diabetes enrolled in a regional diabetes cohort. Fatty liver (FL) and visceral fat area (VFA) was detected by computed tomography scan. sdLDL-C and LDL-TG were measured by our established homogeneous assay. TG rich lipoprotein (TRL) was calculated by subtracting LDL-C plus HDL-C from total-C. Grade of sdLDL-C (≤ 24, 25-34, 35-44, and ≥ 45 mg/dL) was classified according to the Hisayama study.

RESULTS

Compared to non-FL counterparts, FL subjects were younger, predominantly male and smokers; and had higher body mass index (BMI), VFA, hemoglobin A1c, C-peptide, TG, and sdLDL-C, while had similar levels of LDL-C, LDL-TG, and TRL-C. Multivariate logistic analysis revealed that sdLDL-C was the most powerful lipid parameter for identifying FL, independent of TG, HDL-C, BMI, and VFA. The independent association between TG and FL was lost when sdLDL-C was added to the analysis. These results remained the same when lipid-lowering drug users were excluded. After adjustment for confounders, the odds ratio for FL was 2.4-2.7 at sdLDL ≥ 35 mg/dL based on sdLDL ≤ 24 mg/dL.

CONCLUSIONS

sdLDL-C levels are specifically elevated in patients with diabetes and MAFLD, independent of TG and VFA, suggesting liver-centered metabolic abnormalities.

Relationship between small dense low density lipoprotein and cardiovascular events in patients with acute coronary syndrome undergoing percutaneous coronary intervention

BACKGROUND

Residual risk remained significant despite effective low density lipoprotein cholesterol (LDL-C) lowering treatment. Small dense low density lipoprotein cholesterol (sdLDL-C) as part of LDL-C has been found to be predictor of coronary heart disease (CHD) and cardiovascular (CV) events in patients with stable CHD independently of LDL-C. However, to date, few studies have explored the role of sdLDL-C in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI). Accordingly, this study aimed to evaluate the association of sdLDL-C with CV events in patients with ACS undergoing PCI.

METHODS

Patients hospitalized with ACS undergoing PCI were enrolled and followed up for 18 months. The risk of sdLDL-C for CV events was compared according to sdLDL-C quartiles. The primary outcome was major cardiovascular and cerebrovascular adverse events (MACCE), which was the composite of all cause of death, nonfatal myocardial infarction (MI), nonfatal stroke or unplanned repeat revascularization. A Cox proportional hazards regression model was performed to estimate the risk of CV events. Subgroup analysis according to diabetes status and LDL-C were performed separately for MACCE.

RESULTS

A total of 6092 patients were included in the analysis (age: 60.2 ± 10.13 years, male: 75.3%, BMI: 25.9 ± 3.33 kg/m², dyslipidemia: 74.1% and diabetes: 44.5%). During 18 months of follow-up, 320 (5.2%) incident CV events occurred. Compared to the lowest sdLDL-C quartile group, patients in the highest quartile had a greater risk of CV events after multivariable adjustment (HR 1.92; 95% CI 1.37-2.70). In addition, it was mainly due to the increase of unplanned repeat revascularization. In the subgroup analyses, significant association was observed regardless of level of LDL-C and diabetes status.

CONCLUSIONS

Patients with elevated sdLDL-C have a higher risk of CV events in Chinese patients with ACS undergoing PCI, providing additional value for better risk assessment.

Hypertriglyceridemia is a major factor associated with elevated levels of small dense LDL cholesterol in patients with metabolic syndrome

BACKGROUND

We aimed to determine the major contributing component of metabolic syndrome (MetS) that results in an elevated small dense LDL cholesterol (sdLDL-C) concentration and sdLDL-C/LDL-C ratio.

METHODS

Four hundred and forty-seven subjects (225 men; 222 women) with MetS were randomly selected from the Korean Metabolic Syndrome Research Initiatives-Seoul cohort study. Age- and sex-matched healthy controls (181 men; 179 women) were also randomly selected from the same cohort.

RESULTS

A comparison of the median values of the sdLDL-C concentration between subgroups, divided according to whether subjects met or did not meet the criteria for each MetS component in patients with MetS, revealed a significant difference in the sdLDL-C concentration only between subgroups divided according to whether subjects met or did not meet the triglyceride (TG) criteria (P<0.05 for each gender). The TG level showed a good correlation with sdLDL-C concentration (correlation coefficients [r]=0.543 for men; 0.653 for women) and the sdLDL-C/LDL-C ratio (r=0.789 for men; 0.745 for women). Multiple linear regression analyses conducted for the MetS group concordantly identified TG as one of the most significant contributors to sdLDL-C concentration (β=0.1747±0.0105, P<0.0001) and the sdLDL-C/LDL-C ratio (β=6.9518±0.3011, P<0.0001).

CONCLUSIONS

Among five MetS components, only the abnormal TG level was a differentiating factor for sdLDL-C concentration and sdLDL-C/LDL-C ratio. These results were reproducible in both genders, with or without MetS.

HDL2/HDL3 Ratio Changes, Metabolic Syndrome Markers, and Other Factors in a Japanese Population

AIM AND METHODS

The high-density lipoprotein 2 cholesterol (HDL2-C) to HDL3-C ratio is associated with insulin resistance, high-molecular-weight adiponectin (HMW-Ad), and metabolic syndrome (MetS) components and is useful for evaluating MetS in Japanese individuals. We investigated potential associations between changes in HDL2-C/HDL3-C and changes in MetS components, insulin resistance, adipocytokine, lipids, and lifestyle habits in 892 Japanese subjects who underwent annual health examinations twice at a mean interval of 1.1 years. Study subjects were divided into three groups on the basis of HDL2-C/HDL3-C changes.

RESULTS

Average changes in waist circumference (WC) and HDL-C were significantly lower and higher, respectively, in the 0 to ＜0.5 and ≥0.5 HDL2-C/HDL3-C change groups compared with those in the reference group (＜0 HDL2-C/HDL3-C change). Among MetS components, average changes in HDL2-C/HDL3-C were associated with changes in WC and HDL-C. Average changes in HMW-Ad and the homeostasis model assessment of insulin resistance were significantly higher and lower, respectively, in the ≥0.5 HDL2-C/HDL3-C change group compared with those in the reference group. In addition, the average low-density lipoprotein cholesterol (LDL-C) gradually decreased as HDL2-C/HDL3-C increased. The average change in LDL-C was significantly lower in the 0 to ＜0.5 and ≥0.5 HDL2-C/HDL3-C change groups than in the reference group. Moreover, a ≥0.5 HDL2-C/HDL3-C change positively correlated with good lifestyle statuses in terms of smoking, physical activity, and alcohol consumption.

CONCLUSION

Changes in HDL2-C/HDL3-C inversely correlated with changes in WC, insulin resistance, and LDL-C and positively correlated with HMW-Ad and good lifestyle habits. Therefore, HDL2-C/HDL3-C changes comprise a useful marker for both MetS and atherogenic conditions in Japanese population.

Flaxseed oil intake reduces serum small dense low-density lipoprotein concentrations in Japanese men: a randomized, double blind, crossover study

BACKGROUND

The effects of alpha-linolenic acid (ALA) on cardiovascular risk factors considerably vary between published reports. Therefore, we investigated the effects of 12-week supplementation with flaxseed oil (FO), which is a rich source of ALA, on cardiovascular risk factors such as serum small dense low-density lipoprotein (sd-LDL) concentrations.

METHODS

In a randomized, double blind, crossover study, 15 subjects ingested 10 g of FO or corn oil (CO), containing 5.49 g and 0.09 g of ALA, respectively, once daily with dinner. Blood samples were collected at 0, 4 and 12 weeks, and were used for analysis of serum lipid, lipid-related proteins, serum fatty acids and serum sd-LDL cholesterol. Differences during the test period were identified using a repeated-measures analysis of variance (ANOVA) for within-group effects. Group differences were identified using paired t-test at each blood sampling time point.

RESULTS

ALA and eicosapentaenoic acid concentrations were significantly higher in the FO period at 4 and 12 weeks than in the CO period. No significant differences in docosahexaenoic acid concentrations were observed between two periods, and cholesteryl ester transfer protein and apolipoprotein B concentrations were significantly lower in the FO period than in the CO period at 12 weeks. FO supplementation was associated with a significant decrease in sd-LDL concentrations at 4 and 12 weeks, and CO supplementation had no effect. Moreover, sd-LDL concentrations were significantly lower in the FO period than in the CO period at 4 weeks. Among subjects with triglyceride (TG) concentrations of >100 mg/dl, FO supplementation markedly reduced sd-LDL concentrations at 4 and 12 weeks compared with baseline. Sd-LDL concentrations significantly differed between the periods at both 4 and 12 weeks.

CONCLUSION

This study indicates that the FO, which is a rich source of ALA, leads to lower sd-LDL cholesterol concentrations.

Gender disparity in LDL-induced cardiovascular damage and the protective role of estrogens against electronegative LDL

Background

Increased levels of the most electronegative type of LDL, L5, have been observed in the plasma of patients with metabolic syndrome (MetS) and ST-segment elevation myocardial infarction and can induce endothelial dysfunction. Because men have a higher predisposition to developing coronary artery disease than do premenopausal women, we hypothesized that LDL electronegativity is increased in men and promotes endothelial damage.

Methods

L5 levels were compared between middle-aged men and age-matched, premenopausal women with or without MetS. We further studied the effects of gender-influenced LDL electronegativity on aortic cellular senescence and DNA damage in leptin receptor–deficient (db/db) mice by using senescence-associated–β-galactosidase and γH2AX staining, respectively. We also studied the protective effects of 17β-estradiol and genistein against electronegative LDL–induced senescence in cultured bovine aortic endothelial cells (BAECs).

Results

L5 levels were higher in MetS patients than in healthy subjects (P < 0.001), particularly in men (P = 0.001). LDL isolated from male db/db mice was more electronegative than that from male or female wild-type mice. In addition, LDL from male db/db mice contained abundantly more apolipoprotein CIII and induced more BAEC senescence than did female db/db or wild-type LDL. In the aortas of db/db mice but not wild-type mice, we observed cellular senescence and DNA damage, and the effect was more significant in male than in female db/db mice. Pretreatment with 17β-estradiol or genistein inhibited BAEC senescence induced by male or female db/db LDL and downregulated the expression of lectin-like oxidized LDL receptor-1 and tumor necrosis factor-alpha protein.

Conclusion

The gender dichotomy of LDL-induced cardiovascular damage may underlie the increased propensity to coronary artery disease in men.

Small dense LDL cholesterol is a robust therapeutic marker of statin treatment in patients with acute coronary syndrome and metabolic syndrome

BACKGROUND

Small dense low-density lipoprotein (sd-LDL) is an atherogenic LDL subfraction and often increased in metabolic syndrome (MetS). This study aimed to determine whether sd-LDL cholesterol (sd-LDL-C) is a therapeutic marker of statin treatment in patients with acute coronary syndrome (ACS) and MetS.

METHODS

We examined 71 patients with ACS and 50 non-ACS subjects with normal coronary arteries (controls). The patients with ACS were treated with life-style modifications (n=36) or those plus 20mg atorvastatin daily (n=35) for 6 months. We measured sd-LDL-C by a novel detergent-based homogenous assay and calculated buoyant LDL-C (b-LDL-C).

RESULTS

The patients with ACS had higher sd-LDL-C than did the controls (30±14 vs. 22±8 mg/dl, p<0.001). Furthermore, sd-LDL-C was higher in the patients with ACS and MetS (n=31) than in those without MetS (n=40) (35±17 vs. 27±11 mg/dl, p<0.05). Atorvastatin reduced LDL-C and sd-LDL-C by 31% (102±23 to 70±28 mg/dl, p<0.0001) and 24% (29±15 to 22±13 mg/dl, p<0.01). The reduction in sd-LDL-C by atorvastatin was 5.5-fold greater in the patients with ACS and MetS than in those without MetS (p<0.001). Contrary, that in b-LDL-C was similar between the groups.

CONCLUSIONS

sd-LDL-C is a superior therapeutic marker of statin treatment in patients with ACS and MetS.

Apolipoprotein B and non-high-density lipoprotein cholesterol are better risk markers for coronary artery disease than low-density lipoprotein cholesterol in hypertriglyceridemic metabolic syndrome patients

BACKGROUND

Metabolic syndrome is highly prevalent in the general population. Small dense low-density lipoprotein (sd-LDL) particles have been considered as a risk marker in metabolic syndrome diagnosis. Apolipoprotein B (ApoB) concentration reflects the number of LDL particles and is closely associated with atherosclerosis. The aim of this study was to compare the associations of ApoB, non-high-density lipoprotein cholesterol (NHDL-C), and low-density lipoprotein cholesterol (LDL-C) with metabolic syndrome and its relationship with significant coronary stenosis (SCS) in a Tunisian population.

METHODS

We enrolled 192 patients, who underwent coronary angiography. The body mass index, blood lipids, fasting glucose, insulin concentration, and blood pressure of every patient were measured. Metabolic syndrome was diagnosed according to the International Diabetes Federation criteria.

RESULTS

The frequency of metabolic syndrome was 58.3%. The comparison of the lipidic parameters between subject with and without metabolic syndrome showed a significant increase in ApoB and NHDL-C but not in LDL-C. By considering triglyceride (TG) limits (TG ≤ 0.9 mmol/L and TG > 1.70 mmol/L), we noted no differences in ApoB, NHDL-C, and LDL-C between subjects with and without metabolic syndrome in triglyceridemia ≤0.9 mmol/L. In triglyceridemia >1.70 mmol/L, a significant increase in ApoB and NHDL-C, but not in LDL-C, was noted. These results seem to consolidate the probability of increased sd-LDL in hypertriglyceridemic metabolic syndrome subjects. Indeed, in our study the odds ratio (OR) of SCS associated with metabolic syndrome is 3.81 (P = 0.007) in the studied population. This risk increases to 8.70 (P = 0.026) in hypertriglyceridemic subjects and seems to be associated with ApoB and NHDL-C (OR = 1.87, P = 0.038; OR = 1.26, P = 0.048).

CONCLUSIONS

This study suggests that ApoB and NHDL-C seem to be more correlated to SCS in metabolic syndrome with hypertriglyceridemia than LDL-C.

Association between carotid atherosclerosis and metabolic syndrome: results from the ISMIR study

The metabolic syndrome (MetS) has previously been associated with an early marker of atherosclerosis, the carotid intima-media thickness (IMT). From the ISMIR (Ispessimento Medio Intimale e Rischio cardiovascolare [media-intima thickness and cardiovascular risk]) study population of 479 asymptomatic participants, we identified 80 participants with MetS. Carotid IMT and plaques were evaluated by ultrasonography. Blood samples were obtained from all participants. Participants with MetS had a significantly higher prevalence of a carotid IMT > 0.80 mm (P = .004) and of carotid plaques (P < .001) as compared with participants without MetS. Carotid IMT was significantly correlated with fasting triglycerides and fibrinogen levels both in participants with MetS and in those without MetS (all P < .01). In contrast, IMT correlated with fasting plasma glucose, serum creatinine, and uric acid levels only in participants without MetS. Our study confirms the association between MetS and carotid atherosclerosis. In MetS, a significant correlation between carotid IMT and triglycerides and fibrinogen levels was found.

Effects of different statin treatments on small dense low-density lipoprotein in patients with metabolic syndrome

AIM

To compare the effects of different low-density lipoprotein (LDL) cholesterol-lowering statin treatments on small dense LDL (sd-LDL) in hypercholesterolemic patients with metabolic syndrome (MetS).

METHODS

Forty hypercholesterolemic MetS patients ?30 years of age were randomized to rosuvas-tatin (n=17) or other statins (n=23) groups. In the other statins group, those taking atorvastatin (n=12) were also evaluated separately. Statin doses were 10 mg/day rosuvastatin, 20 mg/day atorvas-tatin, 40 mg/day simvastatin, and 40 mg/day pravastatin. Treatment duration was planned to be 8 weeks. Sd-LDL levels were assessed at baseline and at the completion of treatment.

RESULTS

After treatment, sd-LDL levels were significantly reduced in all 3 groups (from 29.6+/-24.8 mg/dL to 8.9+/-8.5 mg/dL in the rosuvastatin group, p=0.001; from 26.2+/-15 mg/dL to 14.8+/-9.6 mg/dL in the atorvastatin group, p=0.02; and from 29.1+/-16.5 mg/dL to 14.7+/-11.2 mg/dL in the other statins group, p=0.0001). There was no significant difference in the mean percent changes among groups.

CONCLUSION

Significant reduction in sd-LDL levels was observed after 8 weeks of statin treatment in hypercholesterolemic patients with MetS. This effect was similar for all statins and can be considered a class effect.

Myo-inositol treatment increases serum plasmalogens and decreases small dense LDL, particularly in hyperlipidemic subjects with metabolic syndrome

BACKGROUND AND AIM

We have previously shown that serum plasmalogen levels positively correlate with HDL, and significantly decrease with aging, and may be related to LDL particle size. The objective of the present study was to investigate the effects of increased serum plasmalogens on lipidosis, particularly the appearance of atherogenic small dense LDL (sdLDL), of subjects with hyperlipidemia and metabolic syndrome (MetS).

METHODS AND RESULTS

The effects of increased serum plasmalogen levels, induced by 2 wk of myo-inositol treatment, on several clinical and biochemical parameters were examined in 17 hyperlipidemic subjects including some with MetS. After myo-inositol treatment, significant increases in plasmalogen-related parameters, particularly ChoPlas, and significant decreases in atherogenic cholesterols including sdLDL, were observed. Among the hyperlipidemic subjects treated with myo-inositol, compared to subjects without MetS, subjects with MetS had a significant increase in plasmalogens and a tendency towards reduced sdLDL, high sensitivity C-reactive protein (hsCRP), and blood glucose levels. Correlation analyses between the measured parameters showed that plasmalogens, as well as HDL, function as beneficial factors, and that sdLDL is a very important risk factor that shows positive correlations with many other risk factors.

CONCLUSION

These results suggest that increased plasmalogen biosynthesis and/or serum levels are especially effective in improving MetS among hyperlipidemic subjects with MetS.

Effects of statin on small dense low-density lipoprotein cholesterol and remnant-like particle cholesterol in heterozygous familial hypercholesterolemia

AIM

The effects of statin on small dense low-density lipoprotein cholesterol (sd-LDL-C) and remnant-like particle cholesterol (RLP-C) levels in heterozygous familial hypercholesterolemia (FH) have not been examined. This study aimed to clarify the effects of statin on sd-LDL-C and RLP-C levels in heterozygous FH.

METHODS

Seventeen patients with heterozygous FH were randomly assigned to 2 mg/day pitavastatin or 10 mg/day atorvastatin. At baseline and 12 weeks after treatment with statin, we measured sd-LDL-C and RLP-C levels.

RESULTS

Sd-LDL-C levels significantly decreased from 43 +/- 24 to 16 +/- 10 mg/dL (-63%, p=0.001) in the pitavastatin group, and from 44 +/- 17 to 19 +/- 10 mg/dL (-55%, p<0.001) in the atorvastatin group. RLP-C levels decreased from 8.4 +/- 2.8 to 6.6 +/- 2.7 mg/dL (-16%, p=0.156) in the pitava-statin group, and from 9.8 +/- 4.7 to 5.9 +/- 5.4 mg/dL (-45%, p=0.044) in the atorvastatin group. There were no significant differences in percent changes of sd-LDL-C (p=0.370) and RLP-C levels (p=0.097) between the two groups.

CONCLUSIONS

Sd-LDL-C measured by the heparin-magnesium precipitation method and RLP-C levels in heterozygous FH were decreased by 12 weeks of statin therapy. Statin might have additional anti-atherogenic effects by reducing not only LDL-C but also sd-LDL-C and RLP-C.