Nuclear Magnetic Resonance Lipoprotein Subclasses and the APOE Genotype Influence Carotid Atherosclerosis in Patients with Systemic Lupus Erythematosus

Mechanistic insight into premature atherosclerosis and cardiovascular complications in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is associated with a significant risk of cardiovascular disease (CVD), which substantially increases disease mortality and morbidity. The overall mechanisms associated with the development of premature atherosclerosis and CVD in SLE remain unclear, but has been considered as a result of an intricate interplay between the profound immune dysregulation and traditional CVD risk factors. Aberrant systemic inflammation in SLE may lead to an abnormal lipid profile and dysfunction, which can further fuel the pro-atherosclerotic environment. The existence of a strong imbalance between endothelial damage and vascular repair/angiogenesis promotes vascular injury, which is the early step in the progression of atherosclerotic CVD. Profound innate and adaptive immune dysregulation, characterized by excessive type I interferon burden, aberrant macrophage, platelet and complements activation, neutrophil dysregulation and neutrophil extracellular traps formation, uncontrolled T cell activation, and excessive autoantibody production and immune complex formation, have been proposed to promote accelerated CVD in SLE. While designing targeted therapies to correct the dysregulated immune activation may be beneficial in the treatment of SLE-related CVD, much additional work is needed to determine how to translate these findings into clinical practice. Additionally, a number of biomarkers display diagnostic potentials in improving CVD risk stratification in SLE, further prospective studies will help understand which biomarker(s) will be the most impactful one(s) in assessing SLE-linked CVD. Continued efforts to identify novel mechanisms and to establish criteria for assessing CVD risk as well as predicting CVD progression are in great need to improve CVD outcomes in SLE.

Relationship between Apolipoprotein E Genotype and Lipoprotein Profile in Patients with Coronary Heart Disease

(1) Background: Apolipoprotein E(ApoE) plays a critical role in lipid transport. The specific allele of APOE being expressed is associated with the development of coronary heart disease (CHD), however the specific mechanisms by which ApoE drives disease are unclear. In this study, we investigated the relationship between APOE allele, lipoprotein metabolome, and CHD severity to provide evidence for the efficacy of clinical cholesterol-lowering therapy; (2) Methods: Blood samples were collected from 360 patients with CHD that were actively being treated with statins. The lipoprotein profile, including particle numbers, particle size, and lipoprotein composition concentrates, was measured by nuclear magnetic resonance (NMR) spectroscopy. The severity of CHD was determined by quantifying coronary angiography results using the Gensini scoring system; (3) Results: We found there was no significant difference in low-density lipoprotein cholesterol (LDL-C) levels among ε2+ (ε2 allele carriers, consisting of ε2/ε2 and ε2/ε3 genotypes), ε3 (consisting of ε3/ε3 and ε2/ε4 genotypes), and ε4+ (ε4 allele carriers, consisting of ε3/ε4 and ε4/ε4 genotypes) participants receiving statin treatment. Compared with the ε3 group, patients with the ε2+ genotype showed lower concentrations of total low-density lipoprotein (LDL), small-LDL, and middle-LDL particles, as well as a larger LDL size, higher very low-density lipoprotein (VLDL) composition concentrates, and higher intermediate density lipoprotein (IDL) composition concentrates. The ε4+ group showed higher concentrations of total LDL, small LDL particles, and LDL compositions with smaller LDL size. The higher level of small LDL concentration was associated with a high Gensini score (B = 0.058, p = 0.024). Compared with the ε3 group, the risk of increased branch lesions in the ε2+ group was lower (OR = 0.416, p = 0.027); (4) Conclusions: The specific allele of APOE being expressed can affect the severity of CHD by altering components of the lipoprotein profile, such as the concentration of small LDL and LDL size.

Asymptomatic Carotid Atherosclerosis Cardiovascular Risk Factors and Common Hypertriglyceridemia Genetic Variants in Patients with Systemic Erythematosus Lupus

SLE is associated with increased cardiovascular risk. The objective of this study was to determine the prevalence of asymptomatic carotid atherosclerosis to analyze its relationship with dyslipidemia and related genetic factors in a population of patients with SLE. Seventy-one SLE female patients were recruited. Carotid ultrasound, laboratory profiles, and genetic analysis of the ZPR1, APOA5, and GCKR genes were performed. SLE patients were divided into two groups according to the presence or absence of carotid plaques. Patients with carotid plaque had higher plasma TG (1.5 vs. 0.9 mmol/L, p = 0.001), Non-HDL-C (3.5 vs. 3.1 mmol/L, p = 0.025), and apoB concentrations (1.0 vs. 0.9 g/L, p = 0.010) and a higher prevalence of hypertension (80 vs. 37.5%, p = 0.003) than patients without carotid plaque. The GCKR C-allele was present in 83.3% and 16.7% (p = 0.047) of patients with and without carotid plaque, respectively. The GCKR CC genotype (OR = 0.026; 95% CI: 0.001 to 0.473, p = 0.014), an increase of 1 mmol/L in TG concentrations (OR = 12.550; 95% CI: 1.703 to 92.475, p = 0.013) and to be hypertensive (OR = 9.691; 95% CI: 1.703 to 84.874, p = 0.040) were independently associated with carotid atherosclerosis. In summary, plasma TG concentrations, CGKR CC homozygosity, and hypertension are independent predictors of carotid atherosclerosis in women with SLE.

Low-density lipoprotein from active SLE patients is more atherogenic to endothelial cells than low-density lipoprotein from the same patients during remission

OBJECTIVES

SLE patients have an enhanced risk of atherosclerosis and cardiovascular disease. However, the increased prevalence of cardiovascular disease is not fully explained by traditional Framingham cardiovascular risk factors. Specific features of low-density lipoprotein (LDL) particles, other than plasma concentration, may induce accelerated atherosclerosis at early stages in these patients. Thus, we aimed to explore the impact of LDL from both active and inactive SLE patients on human aortic endothelial cells.

METHODS

Human aortic endothelial cells were stimulated with the same concentration of LDL particles isolated from pooled serum that was collected from 13 SLE patients during both active and inactive states. Gene expression and cell migration assays were performed.

RESULTS

Circulating LDL particles obtained from healthy volunteers and SLE patients in both remission and flare states were comparable in terms of number, cholesterol and triglyceride content, and net electric charge. Stimulation of cells with LDL from active SLE patients induced the expression of vascular cell adhesion molecule 1 (∼2.0-fold, P < 0.05), monocyte chemoattractant protein 1 (∼2.0-fold, P < 0.05) and matrix metallopeptidase 2 (∼1.6-fold, P < 0.01) compared with cells stimulated with LDL from inactive SLE patients. Additionally, LDL extracted from active patients increased cell migration in a wound-healing assay (1.4-fold, P < 0.05).

CONCLUSION

Our data show that, at the same LDL concentration, LDL from active SLE patients had increased proatherogenic effects on endothelial cells compared with LDL from the same patients when in an inactive or remission state.

High-density lipoprotein functionality in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous disease which is characterized with excessive inflammation and autoantibodies, macrophage and complement activation, and subsequently immunologically mediated tissue damage. In spite of improved treatments of SLE, these patients experience premature atherosclerosis and the rate of mortality among them remains high. Autoantibodies and circulating immune complexes might contribute to the pathogenesis of atherosclerosis by injuring the endothelium, as well as inducing pro-inflammatory and pro-adhesive endothelial cell phenotypes, as well as altering the metabolism of lipoproteins involved in atherogenesis. Hence, high levels of atherogenic lipoproteins (like low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL)) and low levels of high-density lipoprotein (HDL-C) are important risk factors for atherosclerotic cardiovascular complications in SLE patients but these traditional risk factors fail to fully explain the increased risk of cardiovascular disease (CVD) in these patients. The exact mechanism by which inflammation decreases HDL levels is not defined, but decreases in apoA-I production and lecithin cholesterol acyltransferase (LCAT) activity, as well as increased serum amyloid A (SAA), endothelial lipase and secretory phospholipase A2 activity (PLA2) could all contribute. In addition, during inflammation multiple changes in HDL structure occur, leading to alterations in HDL function which may be implicated in the CVD complications of SLE. Therefore, this review will aim to identify the mechanisms implicated in HDL dysfunction which occurs in SLE patients.

Inflammatory joint diseases and atherosclerosis: time to look beyond the 'lipid paradox'

PURPOSE OF REVIEW

Uncertainty persists about the contribution of lipids to the increased risk of cardiovascular disease (CVD) among rheumatoid arthritis and other inflammatory joint disease (IJD) patients. In reviewing recent research, we consider potential insights gained by quantifying lipoprotein particles directly, rather than by their lipid content.

RECENT FINDINGS

Although inflammation often decreases LDL cholesterol (LDL-C), and anti-inflammatory medications often increase LDL-C, both inflammation and anti-inflammatory medications can increase atherogenic Apolipoprotein B (ApoB)-containing lipoprotein particles, attenuated by statins. CVD risk factors, that is, smoking, obesity, ApoB, may increase years prior to IJD diagnosis. Increased risks of nonatherosclerotic myocardial and pulmonary disease, heart failure and mortality may be directly related to disease activity, inflammation, and possibly to HDL particles and function.

SUMMARY

For IJD patients, higher cumulative lifetime exposure to CVD risk factors accelerates atherosclerosis and subsequent CVD risk that is underestimated by current risk factor levels. CVD risk reduction in IJD requires aggressive and earlier reduction in CVD risk factors (ApoB lipoproteins, smoking, hypertension, diabetes, lack of physical activity), in addition to control of disease activity and inflammation. Lipid-lowering medications can attenuate anti-inflammatory medication-induced increases in ApoB and LDL-C, but can also reduce CVD risk due to cumulative lifetime exposure.

Low-density lipoprotein net charge is a risk factor for atherosclerosis in lupus patients independent of lipid concentrations

AIMS

Patients with systemic lupus erythematosus (SLE) suffer from accelerated atherosclerosis. Their most common cause of death is a cardiovascular disease (CVD), in spite of the presence of moderate lipid alterations and normal cardiovascular risk scores. However, cholesterol still accumulates in the arteries of SLE patients, so we aim to identify additional factors that may help explain the residual risk that exists in these patients. We focus on investigating whether the net charge contributes significantly to both the development and the progression of atherosclerosis in patients with SLE.

METHODS

The lipoproteins from 78 patients with SLE and 32 controls were isolated via sequential ultracentrifugation. Lipoprotein subclasses distributions were analyzed via nuclear magnetic resonance spectroscopy and the net charges of very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were measured using a Zetasizer Nano-ZS. The degree of atherosclerosis (carotid intima-media thickness [cIMT]) was determined in all the participants.

RESULTS

Each lipoprotein class exhibited a negative net charge. IDL and LDL net charge correlated negatively with cIMT (r = -0.274, P = 0.034; r = -0.288; P = 0.033, respectively) in patients with SLE. This effect was independent of age, body mass index (BMI), gender, tobacco consumption, high-sensitivity C-reactive protein (hsCRP), lipid concentration and lipoprotein particle number. LDL net charge explained 4% of the cIMT variability among these patients; this contribution was also independent of age, BMI, gender, tobacco consumption, lipids levels, apolipoproteins and hsCRP.

CONCLUSIONS

Low-density lipoprotein net charge may be considered a new independent contributor to subclinical atherosclerosis in SLE patients. The observed relationship was independent of lipid concentrations and extends the prominent role that IDL and LDL play in cardiovascular risk.

Synergism between apolipoprotein E Ɛ4 allele and paraoxonase (PON1) 55-M allele is associated with risk of systemic lupus erythematosus

Evidences indicate that abnormal lipid metabolism and lipid peroxidation can affect the progression of complications in systemic lupus erythematosus (SLE) patients. Apolipoprotein E (ApoE) and paraoxonase-1 (PON1) play important role in lipid metabolism and protection of lipid peroxidation. The polymorphisms of ApoE and paraoxonase (PON1) L55M (Met < Leu) allele genes lead to disorders in lipid metabolism and are related to atherosclerosis. This study is the first investigation to examine the possible association between ApoE and PON1-L55M polymorphisms and correlation with serum arylesterase (ARE) activities of PON, levels of malondialdehyde (MDA), neopterin, and lipid lipoprotein in SLE patients from Iranian western population. The present case-control study consisted of 107 SLE patients and 101 gender- and age-matched, unrelated, healthy controls from Iran's western population. The ApoE and PON1-L55M genotypes were identified using PCR-RFLP method. The serum level of MDA, neopterin, lipid levels, and ARE activity were determined by HPLC, commercial kits, and spectrophotometry, respectively. Our results showed that ApoE ε4 and PON1-55M alleles act synergistically to increase the risk of SLE by 1.47 times (p = 0.038). We found that the frequency of ApoE Ɛ3/Ɛ4 genotype was higher in SLE patients (11.2%) compared with control subjects (5%), although the difference was not significant (p = 0.087). This study for the first time not only demonstrates that ApoE Ɛ4 and PON-55M alleles synergistically increase the risk of SLE but also reveals that serum levels of MDA, neopterin, and LDL-C are high in SLE patients. This information may be in value for evaluating SLE progression and in the elucidation of the mechanisms of the disease pathogenesis.

Cardiovascular disease in systemic lupus erythematosus: A comprehensive update

Heightened rates of both cardiovascular (CV) events and subclinical atherosclerosis, documented by imaging and vascular function techniques are well established in systemic lupus erythematosus (SLE). While traditional CV factors such as smoking, dyslipidemia, diabetes mellitus (DM), hypertension, central obesity and hyperhomocysteinemia have been reported to be prevalent in lupus patients, they do not fully explain the high rates of ischemic events so far reported, implying that other factors inherent to disease itself could account for the enhanced risk, including disease duration, activity and chronicity, psychosocial factors, medications, genetic variants and altered immunological mechanisms. Though the exact pathogenesis of atherosclerosis in the setting of lupus remains ill defined, an imbalance between endothelial damage and atheroprotection seems to be a central event. Insults leading to endothelial damage in the setting of lupus include oxidized low density lipoprotein (oxLDL), autoantibodies against endothelial cells and phospholipids, type I interferons (IFN) and neutrophil extracellular traps (NETs) directly or through activation of type I IFN pathway. Increased oxidative stress, reduced levels of the normally antioxidant high density lipoprotein (HDL), increased levels of proinflammatory HDL (piHDL) and reduced paraoxonase activity have been related to increased oxLDL levels. On the other hand, impaired atheroprotective mechanisms in lupus include decreased capacity of endothelial repair-partly mediated by type I IFN- and dampened production of atheroprotective autoantibodies. In the present review, traditional and disease related risk factors for CV disease (CVD) in the setting of chronic autoimmune disorders with special focus on SLE will be discussed.

Angiotensin type 1 receptor A1166C polymorphism and systemic lupus erythematosus: correlation with cellular immunity and oxidative stress markers

Angiotensin II, one of the rennin–angiotensin system components, is important in the cardiovascular hemodynamic and plays an important role in the development of cardiovascular disease in systemic lupus erythematosus (SLE) patients. The angiotensin II, through interaction with angiotensin II type 1 receptor (AGTR1), promotes proliferation, inflammation and fibrosis. The single nucleotide polymorphism of the AGTR1 (dbSNP: rs5186) gene can be associated with development and progression of SLE disease. The aims of this study were to compare the frequency of AGTR1 rs5186 in SLE patients with healthy individuals and to evaluate possible association between AGTR1 A1166C gene polymorphism and serum level of lipids, neopterin and malondialdehyde in SLE patients from a population of West Iran. One hundred SLE patients and 98 healthy subjects were studied. The AGTR1 A1166C polymorphism was detected by polymerase chain reaction– restriction fragment length polymorphism method and the serum lipid profile was obtained by enzymatic method. Neopterin and malondialdehyde were detected using high-performance liquid chromatography. We did not detect significant association between AGTR1 A1166C polymorphism and the risk of SLE. The levels of triglyceride (225 ± 118 mg/dl), neopterin (30 ± 24 nmol/l) and malondialdehyde (25 ± 9.6 nmol/l) in SLE patients were significantly higher than those in control subjects (139 ± 56 mg/dl, p = 0.03, 6.4 ± 2, p = 0.03, 9.4 ± 2.5 nmol/l, p = 0.01, respectively). Individuals with AGTR1 AC + CC genotype had higher levels of total cholesterol and malondialdehyde compared with those with AGTR1 AA genotype. SLE patients with either AGTR1 AA or AGTR1AC + CC genotype had significantly higher malondialdehyde or neopterin levels compared with the corresponding control subjects. In conclusion, although the present study did not find any association between AGTR1 A1166C polymorphism and the risk of SLE, the presence of this polymorphism was associated with higher levels of malondialdehyde and higher concentration of neopterin in patients.

Longitudinal Evaluation of Lipoprotein Variables in Systemic Lupus Erythematosus Reveals Adverse Changes with Disease Activity and Prednisone and More Favorable Profiles with Hydroxychloroquine Therapy

OBJECTIVE

Systemic lupus erythematosus (SLE) is associated with accelerated atherosclerotic cardiovascular disease. Patients with SLE have adverse lipoprotein variables, but little is known about how these change with treatment and disease activity. The nuclear magnetic resonance LipoProfile test contains a glycoprotein signal-termed GlycA, an inflammatory marker, which has not been evaluated in SLE. We assessed patients longitudinally to determine how lipoproteins and GlycA change with active SLE.

METHODS

Sera from selected clinical visits of patients in the Hopkins Lupus Cohort were analyzed for lipoprotein and GlycA levels. Univariate and multivariate analyses were performed to evaluate lipoprotein variables and their relationship to ethnicity, disease activity, prednisone use, and hydroxychloroquine (HCQ) therapy.

RESULTS

Fifty-two patients were included over 229 visits. Adverse changes in lipoprotein variables with disease activity were demonstrated. For each point increase in the Systemic Lupus Erythematosus Disease Activity Index, there was a decrease in high-density lipoprotein (HDL) even after adjusting for corticosteroid use. Prednisone was associated with higher very low-density lipoprotein, low-density lipoprotein, HDL, and triglycerides. HCQ was associated with more favorable variables. GlycA levels were higher than in normal populations and increased with disease activity.

CONCLUSION

Adverse changes in lipoprotein profiles were associated with SLE activity and prednisone therapy. This gives insight into mechanisms of atherosclerosis in SLE. Favorable lipoprotein variables occurred in those taking HCQ. GlycA increased with disease activity and was higher than in healthy populations.

Improving Assessment of Lipoprotein Profile in Type 1 Diabetes by 1H NMR Spectroscopy

Patients with type 1 diabetes (T1D) present increased risk of cardiovascular disease (CVD). The aim of this study is to improve the assessment of lipoprotein profile in patients with T1D by using a robust developed method 1H nuclear magnetic resonance spectroscopy (1H NMR), for further correlation with clinical factors associated to CVD. Thirty patients with T1D and 30 non-diabetes control (CT) subjects, matched for gender, age, body composition (DXA, BMI, waist/hip ratio), regular physical activity levels and cardiorespiratory capacity (VO_2peak), were analyzed. Dietary records and routine lipids were assessed. Serum lipoprotein particle subfractions, particle sizes, and cholesterol and triglycerides subfractions were analyzed by 1H NMR. It was evidenced that subjects with T1D presented lower concentrations of small LDL cholesterol, medium VLDL particles, large VLDL triglycerides, and total triglycerides as compared to CT subjects. Women with T1D presented a positive association with HDL size (p<0.005; R = 0.601) and large HDL triglycerides (p<0.005; R = 0.534) and negative (p<0.005; R = -0.586) to small HDL triglycerides. Body fat composition represented an important factor independently of normal BMI, with large LDL particles presenting a positive correlation to total body fat (p<0.005; R = 0.505), and total LDL cholesterol and small LDL cholesterol a positive correlation (p<0.005; R = 0.502 and R = 0.552, respectively) to abdominal fat in T1D subjects; meanwhile, in CT subjects, body fat composition was mainly associated to HDL subclasses. VO_2peak was negatively associated (p<0.005; R = -0.520) to large LDL-particles only in the group of patients with T1D. In conclusion, patients with T1D with adequate glycemic control and BMI and without chronic complications presented a more favourable lipoprotein profile as compared to control counterparts. In addition, slight alterations in BMI and/or body fat composition showed to be relevant to provoking alterations in lipoproteins profiles. Finally, body fat composition appears to be a determinant for cardioprotector lipoprotein profile.

APOA5 variants predispose hyperlipidemic patients to atherogenic dyslipidemia and subclinical atherosclerosis

BACKGROUND

Triglycerides (TG) are the initiators of the metabolic changes leading to the atherogenic dyslipidemia, which is a major inducer of atherosclerosis as a result of quantitative and qualitative changes in lipoprotein subclass distributions. We hypothesized that variation at the of APOA5 gene locus, encoding apoAV, a key regulator of TG levels, significantly affect lipoprotein subclass distributions toward a more atherogenic pattern in both hyperTG patients and dyslipemic patients.

METHODS

We recruited four hundred and twenty-two subjects attending a Lipid Clinic, prior to lipid-lowering treatment. We genotyped two APOA5 variants, rs662799 (-1131T>C) and rs3135506 (S19W). Circulating lipoproteins were determined by nuclear magnetic resonance (NMR). Intima-media thickness (IMT) was evaluated using B-mode ultrasound.

RESULTS

Carriers of the rare alleles of rs662799 and rs3135506 compared to common allele homozygotes, had a significantly proatherogenic profile of the VLDL and LDL subclasses, resulting in increased concentrations of the proatherogenic subclasses, large VLDLs (+133%, p<0.001) and small LDLs (+34%, p=0.014). Significant changes in smaller HDL (+71%, p=0.032), as well as an 18% decrease in large HDL (p=0.046), were also been observed. This atherogenic NMR subclass distribution was significantly associated with increased carotid IMT. The observed effects were significantly stronger in patients with a BMI≥25 kg/m2 and in male and female patients with a waist circumference≥90 cm or ≥85 cm, respectively.

CONCLUSION

In a dyslipemic population, genetic variants of APOA5 modulate lipoprotein subclass distributions, inducing an atherogenic profile associated with IMT defined subclinical atherosclerosis.

The pleiotropic role of HDL in autoimmune diseases

As is widely known, the classic function of HDL is reverse cholesterol transport (RCT), thus removing cholesterol from peripheral tissues. Early epidemiological studies, such as Framingham's, stated that increased HDL levels were associated with a significant decrease in relative risk for cardiovascular disease (CVD) mortality. However, those with heightened expectations in recent years for the development of therapeutic targets to increase HDL levels have been disappointed, because efforts have demonstrated the opposite effect on cardiovascular and global mortality. However, in contrast, studies have highlighted the complexity and the intriguing role of HDL in different pathological conditions, such as infections, neoplasms, and autoimmune diseases. In this review an attempt is made to summarize some biological pathways that link HDL function with the immune system, and its possible clinical repercussions in autoimmune diseases.

Circulating FABP4 is a marker of metabolic and cardiovascular risk in SLE patients

The aim of this study is to determine if circulating fatty acid-binding protein 4 (FABP4) plasma levels are a possible marker of metabolic risk in SLE patients. Circulating levels of adipose FABP4 are associated with adiposity, insulin resistance (IR), metabolic syndrome, diabetes and cardiovascular diseases. Patients affected by systemic lupus erythematosus (SLE) show an accelerated atherosclerosis that cannot be entirely explained by traditional cardiovascular risk factors. Sixty consecutive patients with SLE and 34 non-SLE age-matched controls were recruited for the study. Total plasma lipids and circulating FABP4 were determined. Subclinical atherosclerosis was evaluated by measuring carotid intimae-media thickness (c-IMT) by sonography, and the distribution of lipoprotein subclasses was analysed by nuclear magnetic resonance (NMR) spectroscopy. In the SLE group, FABP4 was associated with IR, atherogenic dyslipidaemia, as measured by NMR, and the presence of subclinical atherosclerosis. In multivariate analyses FABP4 was associated with increased c-IMT independent of the inflammatory state of the patient. In sum, circulating FABP4 is involved in the metabolic disturbances of SLE affecting lipid metabolism and IR, and it could be a biomarker of atherosclerosis in this population.