Advanced lipoprotein profile identifies atherosclerosis better than conventional lipids in type 1 diabetes at high cardiovascular risk

BACKGROUND AND AIMS

People with type 1 diabetes (T1D) present lipoprotein disturbances that could contribute to their increased cardiovascular disease (CVD) risk. We evaluated the relationship between lipoprotein alterations and atherosclerosis in patients with T1D.

METHODS AND RESULTS

Cross-sectional study in subjects with T1D, without previous CVD, but high-risk (≥40 years, nephropathy, or ≥10 years of evolution of diabetes with another risk factor). The presence of plaque (intima-media thickness ≥1.5 mm) in the different carotid segments was determined by ultrasound. The advanced lipoprotein profile was analysed by magnetic resonance imaging (¹H NMR). We included 189 patients (42% women, 47.8 ± 10.7 years, duration of diabetes 27.3 ± 10.1 years, HbA1c 7.5% [7-8]). Those with carotid plaques (35%) were older, with longer diabetes duration, had a higher prevalence of hypertension, and showed lower and smaller LDL particles (LDL-P) and HDL particles (HDL-P), but higher VLDL particles (VLDL-P). Some LDL, HDL and VLDL-related parameters were associated with atherosclerosis in sex, age and statin use adjusted models (p < 0.05), but after adjusting for multiple confounders, including conventional lipid parameters, only HDL-P (OR 0.440 [0.204-0.951]; p = 0.037), medium HDL-P (OR 0.754 [0.590-0.963]; p = 0.024), HDL-P cholesterol content (OR 0.692 [0.495-0.968]; p = 0.032), ¹H NMR LDL-P number/conventional LDL-cholesterol (OR 1.144 [1.026-1.275]; p = 0.015), and ¹H NMR non-HDL particle number/conventional non-HDL-cholesterol ratios (OR 1.178 [1.019-1.361], p = 0.026) remained associated with atherosclerosis.

CONCLUSIONS

In adults with T1D at high-risk, variables related to HDL, LDL and total atherogenic particle number are independently associated with preclinical atherosclerosis. Advanced lipoprotein profiling could be used to identify those at the highest risk of CVD.

Low-density lipoprotein encapsulated thiosemicarbazone metal complexes is active targeting vehicle for breast, lung, and prostate cancers

Cancer is a leading cause of death worldwide and affects society in terms of the number of lives lost. Current cancer treatments are based on conventional chemotherapy which is nonspecific in targeting cancer. Therefore, intensive efforts are underway to better target cancer-specific cells while minimizing the side effects on healthy tissues by using LDL particles as active drug delivery vehicles. The goal is to encapsulate anticancer agents thiosemicarbazone metal-ligand complexes into LDL particles to increase the cytotoxic effect of the agent by internalization through LDL receptors into MCF7, A549, and C42 cancer cell lines as segregate models for biological evaluations targeting tubulin. Zeta potential data of LDL-particles encapsulated anticancer agents showed an acceptable diameter range between 66–91 nm and uniform particle morphology. The results showed cell proliferation reduction in all tested cell lines. The IC₅₀ values of LDL encapsulated thiosemicarbazone metal-ligand complexes treated with MCF7, A549, and C42 ranged between 1.18–6.61 µM, 1.17–9.66 µM, and 1.01–6.62 µM, respectively. Western blot analysis showed a potent decrease in tubulin expression when the cell lines were treated with LDL particles encapsulated with thiosemicarbazone metal-ligand complexes as anticancer agents. In conclusion, the data provide strong evidence that LDL particles are used as an active drug delivery strategy for cancer therapy.

Triglyceride-rich lipoprotein and LDL particle subfractions and their association with incident type 2 diabetes: the PREVEND study

Background

Triglyceride-rich lipoproteins particles (TRLP) and low density lipoprotein particles (LDLP) vary in size. Their association with β-cell function is not well described. We determined associations of TRLP and LDLP subfractions with β-cell function, estimated as HOMA-β, and evaluated their associations with incident T2D in the general population.

Methods

We included 4818 subjects of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study without T2D at baseline. TRLP and LDLP subfraction concentrations and their average sizes were measured using the LP4 algorithm of the Vantera nuclear magnetic resonance platform. HOMA-IR was used as measure of insulin resistance. HOMA-β was used as a proxy of β-cell function.

Results

In subjects without T2D at baseline, very large TRLP, and LDL size were inversely associated with HOMA-β, whereas large TRLP were positively associated with HOMA-β when taking account of HOMA-IR. During a median follow-up of 7.3 years, 263 participants developed T2D. In multivariable-adjusted Cox regression models, higher concentrations of total, very large, large, and very small TRLP (reflecting remnants lipoproteins) and greater TRL size were associated with an increased T2D risk after adjustment for relevant covariates, including age, sex, BMI, HDL-C, HOMA-β, and HOMA-IR. On the contrary, higher concentrations of large LDLP and greater LDL size were associated with a lower risk of developing T2D.

Conclusions

Specific TRL and LDL particle characteristics are associated with β-cell function taking account of HOMA-IR. Moreover, TRL and LDL particle characteristics are differently associated with incident T2D, even when taking account of HOMA-β and HOMA-IR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01348-w.

Riboflavin-Sensitized Photooxidation of Low-Density-Lipoprotein (LDL) Cholesterol: A Culprit in the Development of Cardiovascular Diseases (CVDs)

The oxidation of human low-density-lipoprotein (LDL) particles is responsible for the development of cardiovascular diseases (CVDs). In the present study, the occurrence of riboflavin-sensitized photooxidation of LDL particles was examined in an in vitro system. The presence of light, oxygen, and photosensitizer (50 μM riboflavin) caused the riboflavin-sensitized photooxidation of human LDL particles thereby increasing in the conjugated dienes (CDs) by 32.5 ± 4.8% (p < 0.05), indicating that this could serve as a major culprit in the development of CVDs. A 1 h radiation caused a 63.6 ± 0.3% degradation of the riboflavin content, and this indicates the extremely fast reaction of the riboflavin-sensitized photooxidation. The singlet oxygen quenching capacity of β-carotene was determined at three different concentrations (10, 50, and 100 μM), exhibiting both antioxidant and prooxidant effects, depending on the concentrations used. In addition, ascorbic acid displayed a high incorporation rate into the LDL particles, implying its potential in preventing riboflavin photosensitization of LDL particles. To the best of our knowledge, this is the first report on the riboflavin-sensitized photooxidation of LDL particles in an in vitro system, proposing a new possible mechanism in the development of CVDs.

Atherogenic properties of LDL particles after switching from Truvada or Kivexa plus lopinavir/r to lamivudine plus lopinavir/r: OLE-MET substudy

BACKGROUND

The objective of this study was to determine the impact of tenofovir or abacavir discontinuation on low-density lipoprotein (LDL) phenotype and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity in HIV-infected patients treated with lopinavir/ritonavir plus 2 nucleos(t)ide reverse transcriptase inhibitors (NRTI).

METHODS

Multicenter, open-label study. Patients were randomized to continue with lopinavir/ritonavir plus 2 NRTI (triple therapy) or to switch to lopinavir/ritonavir plus lamivudine (dual therapy). LDL phenotype (by gradient gel electrophoresis) and Lp-PLA2 (by 2-thio-PAF) were determined at baseline and week 48.

RESULTS

Forty-four patients included (triple therapy n = 19, dual therapy n = 25): men 63.6%, age 41.5 years (25-61), Framingham score 4.9% (0.2-22). Tenofovir was part of the regimen in 28 (63.6%) patients. Dual therapy patients were younger (p = 0.013) and had lower baseline apolipoprotein A1 (p = 0.029). At week 48, there were no changes in standard lipid measurements, except ApoA1/Apo B, which increased in dual therapy (p = 0.038) with no differences between arms. At week 48, no change in LDL phenotype was found in either arm. No changes in total Lp-PLA2 activity or the relative distribution of LDL and HDL particles were found at week 48 in either arm.

CONCLUSIONS

Discontinuing the third nucleos(t)ide, mainly tenofovir and abacavir, in a lopinavir/ritonavir-containing regimen was not associated with a deleterious effect on LDL phenotype nor in Lp-PLA2 activity.

Mendelian randomization analysis in three Japanese populations supports a causal role of alcohol consumption in lowering low-density lipid cholesterol levels and particle numbers

BACKGROUND AND AIMS

While alcohol consumption is known to increase plasma high-density lipoprotein (HDL) cholesterol levels, its relationship with low-density lipoprotein (LDL) cholesterol levels is unclear. Aldehyde dehydrogenase 2 (ALDH2) is a rate-controlling enzyme in alcohol metabolism, but a large number of Japanese people have the inactive allele. Here, we conducted a Mendelian randomization analysis using the ALDH2 genotype to clarify a causal role of alcohol on circulating cholesterol levels and lipoprotein particle numbers.

METHODS

This study was conducted in three independent general Japanese populations (men, n = 2289; women, n = 1940; mean age 63.3 ± 11.2 years). Alcohol consumption was assessed using a questionnaire. Lipoprotein particle numbers were determined by nuclear magnetic resonance spectroscopy.

RESULTS

Alcohol consumption increased linearly in proportion to the number of subjects carrying the enzymatically active *1 allele in men (p < 0.001). The *1 allele was also positively associated with HDL cholesterol level (adjusted mean ± standard error, *1*1: 60 ± 0.5, *1*2: 56 ± 0.6, *2*2: 55 ± 1.3 mg/dl, p < 0.001) and inversely associated with LDL cholesterol level (116 ± 0.9, 124 ± 1.1, 130 ± 2.6 mg/dl, p < 0.001). The *1 allele was also positively associated with HDL particle numbers (per-allele: 2.60 ± 0.32 μmol/l, p < 0.001) and inversely associated with LDL particle numbers (-67.8 ± 19.6 nmol/l, p = 0.001). Additional Mendelian randomization analysis failed to clarify the involvement of cholesteryl ester transfer protein in alcohol-related changes in lipoprotein cholesterol levels. No significant association was observed in women, presumably due to their small amount of alcohol intake.

CONCLUSIONS

Alcohol consumption has a causal role in not only increasing HDL cholesterol levels but also decreasing LDL cholesterol levels and particle numbers.

Oxidative stress and hemoglobin-cholesterol adduct in renal patients with different LDL phenotypes

PURPOSE

Unfavorable lipid profile is a major risk factor for cardiovascular disease in renal pathology. In this study, we compared chronic renal patients and healthy controls with different LDL phenotypes (A or B) in respect of various biochemical parameters related to cardiovascular disease.

METHODS

Oxidative stress and anti-oxidative defense parameters [thiobarbituric acid-reacting substances (TBARS), total oxidative status (TOS), total anti-oxidative status (TAS), total protein sulfhydryl (-SH) groups], as well as red blood cell cholesterol distribution were assessed in 40 renal patients and 40 control subjects by standardized assays. LDL particle diameters were determined by polyacrylamide gradient gel electrophoresis. LDL particles are subdivided according to their size into large LDL A phenotype (diameter >25.5 nm) and small LDL B phenotype (diameter ≤25.5 nm).

RESULTS

Renal patients with LDL A phenotype had increased oxidative stress (TOS: p < 0.01, and TBARS: p < 0.001) and decreased total SH- groups (p < 0.001) compared to controls with the same LDL phenotype. A notable decrease in hemoglobin-cholesterol adduct was detected in patients with LDL A phenotype (p < 0.001) and LDL B phenotype (p < 0.05) compared with appropriate controls. LDL B phenotype was characterized with increased TBARS (p < 0.05) compared with LDL A phenotype in control group.

CONCLUSION

Increased oxidative stress, decreased anti-oxidative defense followed with unfavorable changes in hemoglobin-cholesterol binding capacity, could have important influence on cardiovascular disease risk in renal patients regardless of LDL phenotype.

The effect of LDL particles on the behaviour of epithelial noncancer and cancer cell lines after in vitro induced injury

Cell spreading capability and cell proliferation are the major processes in wound healing of injured epithelia as well as in tumour progression. The effect of low-density lipoprotein (LDL) particles as a major extracellular source of cholesterol was evaluated in the re-epithelisation assay of in vitro induced injury. We selected two noncancer cell lines with different dependence on LDL concentrations, the kidney epithelial cells (MDCK) with higher dependence and keratinocytes (HaCaT) with lower dependence on LDL, and three cancer cell lines originating from epithelial cells: A549 (alveolar), CaCo-2 (intestinal) and RT4 (urothelial). All cells were incubated in a control medium, in an LDL-enriched medium or in an LDL-deficient medium. The LDL-enriched medium stimulated cell spreading of MDCK cells which, together with increased proliferation of these cells, resulted in an enhanced re-epithelisation of in vitro induced injury. LDL deficiency caused lower cell spreading which resulted in a decreased re-epithelisation despite the higher proliferation of MDCK cells in this medium. The re-epithelisation of keratinocytes (HaCaT) was not affected by altered LDL concentrations. In cancer cell lines A549, CaCo-2 and RT4, wide heterogeneity regarding cell proliferation and spreading capability was observed after treatment with different LDL concentrations. LDL had no influence on actin filament and tight junction distribution in any of the tested cell lines. The cholesterol content of all cell types, except for CaCo-2 cells, proved to be independent of the LDL level. Further research of the beneficial effects of LDL is needed to prove LDL as a safe enhancer of epithelial wound healing.

Nuclear magnetic resonance-determined lipoprotein subclasses and carotid intima-media thickness in type 1 diabetes

BACKGROUND

Dyslipidemia has been linked to vascular complications of Type 1 diabetes (T1DM). We investigated the prospective associations of nuclear magnetic resonance-determined lipoprotein subclass profiles (NMR-LSP) and conventional lipid profiles with carotid intima-media thickness (IMT) in T1DM.

METHODS

NMR-LSP and conventional lipids were measured in a subset of Diabetes Control and Complications Trial (DCCT) participants (n = 455) at study entry ('baseline', 1983-89), and were related to carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC Year 12 (2004-2006). Associations were defined using multiple linear regression stratified by gender, and following adjustment for HbA1c, diabetes duration, body mass index, albuminuria, DCCT randomization group, smoking status, statin use, and ultrasound devices.

RESULTS

In men, significant positive associations were observed between some baseline NMR-subclasses of LDL (total IDL/LDL and large LDL) and common and/or internal carotid IMT, and between conventional total- and LDL-cholesterol and non-HDL-cholesterol and common carotid IMT, at EDIC Year 12; these persisted in adjusted analyses (p < 0.05). Large LDL particles and conventional triglycerides were positively associated with common carotid IMT changes over 12 years (p < 0.05). Inverse associations of mean HDL diameter and large HDL concentrations, and positive associations of small LDL with common and/or internal carotid IMT (all p < 0.05) were found, but did not persist in adjusted analyses. No significant associations were observed in women.

CONCLUSION

NMR-LSP-derived LDL particles, in addition to conventional lipid profiles, may help in identifying men with T1DM at highest risk for vascular disease.

Associations of small dense low-density lipoprotein and adiponectin with complications of type 2 diabetes

BACKGROUND

Small dense low-density lipoprotein (sd-LDL) has been demonstrated to be associated with cardiovascular diseases (CVD). The proposed atherogenic properties of hypoadiponectinemia might be mediated through increased sd-LDL. In this study, the associations of sd-LDL with cardiovascular and other complications of diabetes, and also with plasma levels of adiponectin, were investigated in diabetic patients.

METHODS

173 patients, with documented type 2 diabetes mellitus, were enrolled in this cross-sectional study. Laboratory, anthropometric, and clinical characteristics were all determined. The presence of CVD, hypertention, and microalbuminuria were also evaluated. Homeostasis model assessment of insulin resistance was calculated.

RESULTS

Sd-LDL concentrations were significantly lower in patients with CVD than those without CVD (p = 0.020); and also lower in hypertensive patients relative to non-hypertensive ones (p = 0.008). Serum levels of adiponectin were significantly lower in patients with CVD (p < 0.001), and hypertension (p = 0.002), compared with those without each of these complications. Sd-LDL and adiponectin concentrations were positively correlated (r = 0.36, p < 0.001). Sd-LDL was also significantly associated with HbA1c (r = 0.24, p = 0.002).

CONCLUSION

Our data suggest that decreased levels of adiponectin might be associated with developing complications of diabetes. This study did not provide any supportive results for the association of increased sd-LDL concentrations with CVD; neither for its association with other complications of diabetes.