Andrea Moreira Monteiro

High circulating autoantibodies against human oxidized low-density lipoprotein are related to stable and lower titers to unstable clinical situation

BACKGROUND Oxidized lipoproteins and antibodies anti-oxidized low-density lipoprotein (anti-oxLDL) have been detected in human plasma and in atherosclerotic lesions. However, the role of these autoantibodies in the maintenance of vascular health or in the pathogenesis of acute vascular insults remains unclear. We examined the relationship of human immunoglobulin G (IgG) anti-oxLDL antibodies with cardiovascular disease risk markers in stable subjects and in patients after an acute coronary syndrome (ACS). METHODS Titers of human anti-oxLDL antibodies were measured in hypertensive subjects in primary prevention (n=94), without other risk factors, and in individuals after a recent ACS event who also had metabolic syndrome (n=116). Autoantibodies against copper ion oxidized LDL were measured by enzyme-linked-immunosorbent assay. RESULTS Anti-oxLDL titers were higher in hypertensive patients and these subjects presented lower high sensitivity C-reactive protein (hs-CRP) than those with ACS (p<0.0001). We found significant correlations between anti-oxLDL and hs-CRP (r=-0.284), body mass index (r=-0.256), waist circumference (r=-0.368), apolipoprotein B (r=-0.191), glucose (r=-0.303), systolic blood pressure (r=0.319), diastolic blood pressure (r=0.167), high-density lipoprotein cholesterol (r=0.224) and apolipoprotein A1 (r=0.257) (p<0.02 for all). After multiple linear regression hs-CRP, fasting glucose and waist circumference remained independently and inversely associated with anti-oxLDL. CONCLUSIONS Acute inflammatory and metabolic conditions decrease titers of human antibodies of IgG class against oxidized LDL, and that circulating anti-oxLDL antibodies could be associated with a protective role in atherosclerosis.

Early increase in autoantibodies against human oxidized low-density lipoprotein in hypertensive patients after blood pressure control.

BACKGROUND Oxidized lipoproteins and antioxidized low-density lipoprotein (anti-oxLDL) antibodies (Abs) have been detected in plasma in response to blood pressure (BP) elevation, suggesting the participation of the adaptive immune system. Therefore, treatment of hypertension may act on the immune response by decreasing oxidation stimuli. However, this issue has not been addressed. Thus, we have here analyzed anti-oxLDL Abs in untreated (naive) hypertensive patients shortly after initiation of antihypertensive therapeutic regimens. METHODS Titers of anti-oxLDL Abs were measured in subjects with recently diagnosed hypertension on stage 1 (n = 94), in primary prevention of coronary disease, with no other risk factors, and naive of antihypertensive medication at entry. Subjects were randomly assigned to receive perindopril, hydrochlorothiazide (HCTZ), or indapamide (INDA) for 12 weeks, with additional perindopril if necessary to achieve BP control. Abs against copper-oxidized LDL were measured by enzyme-linked immunosorbent assay. RESULTS Twelve-week antihypertensive treatment reduced both office-based and 24-h ambulatory BP measurements (P < 0.0005). The decrease in BP was accompanied by reduction in thiobarbituric acid-reactive substances (TBARS) (P < 0.05), increase in anti-oxLDL Ab titers (P < 0.005), and improvement in flow-mediated dilation (FMD) (P < 0.0005), independently of treatment. Although BP was reduced, we observed favorable changes in anti-oxLDL titers and FMD. CONCLUSIONS We observed that anti-oxLDL Ab titers increase after antihypertensive therapy in primary prevention when achieving BP targets. Our results are in agreement with the concept that propensity to oxidation is increased by essential hypertension and anti-oxLDL Abs may be protective and potential biomarkers for the follow-up of hypertension treatment.

Effect of Oxidation on the Structure of Human Low- and High-Density Lipoproteins

This work presents a controlled study of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) structural changes due to in vitro oxidation with copper ions. The changes were studied by small-angle x-ray scattering (SAXS) and dynamic light scattering (DLS) techniques in the case of LDL and by SAXS, DLS, and Z-scan (ZS) techniques in the case of HDL. SAXS data were analyzed with a to our knowledge new deconvolution method. This method provides the electron density profile of the samples directly from the intensity scattering of the monomers. Results show that LDL particles oxidized for 18 h show significant structural changes when compared to nonoxidized particles. Changes were observed in the electrical density profile, in size polydispersity, and in the degree of flexibility of the APO-B protein on the particle. HDL optical results obtained with the ZS technique showed a decrease of the amplitude of the nonlinear optical signal as a function of oxidation time. In contrast to LDL results reported in the literature, the HDL ZS signal does not lead to a complete loss of nonlinear optical signal after 18 h of copper oxidation. Also, the SAXS results did not indicate significant structural changes due to oxidation of HDL particles, and DLS results showed that a small number of oligomers formed in the sample oxidized for 18 h. All experimental results for the HDL samples indicate that this lipoprotein is more resistant to the oxidation process than are LDL particles.

Enhancement on the Europium emission band of Europium chlortetracycline complex in the presence of LDL

Low-density lipoprotein (LDL) particles are the major cholesterol-carrying lipoprotein in the human circulation from the liver to peripheral tissues. High levels of LDL-Cholesterol (LDL-C) are known risk factor for the development of coronary artery disease (CAD). The most common approach to determine the LDL-C in the clinical laboratory involves the Friedewald formula. However, in certain situations, this approach is inadequate. In this paper we report on the enhancement on the Europium emission band of Europium chlortetracycline complex (CTEu) in the presence of LDL. The emission intensity at 615 nm of the CTEu increases with increasing amounts of LDL. This phenomenon allowed us to propose a method to determine the LDL concentration in a sample composed by an aqueous solution of LDL. With this result we obtained LDL calibration curve, LOD (limit of detection) of 0.49 mg/mL and SD (standard deviation) of 0.003. We observed that CTEu complex provides a wider dynamic concentration-range for LDL determination than that from Eu-tetracycline previously. The averaged emission lifetimes of the CTEu and CTEu with LDL (1.5 mg/mL) complexes were measured as 15 and 46 micros, respectively. Study with some metallic interferents is presented.

Measurement of the nonlinear optical response of low-density lipoprotein solutions from patients with periodontitis before and after periodontal treatment: evaluation of cardiovascular risk markers

Abstract. The Z-Scan (ZS) technique in the thermal regime has been used to measure the nonlinear optical response of low-density lipoprotein (LDL). The ZS technique is carried out in LDL from 40 patients with chronic periodontitis before and after three, six, and 12 months of periodontal treatment. Clinical parameters such as probing depths, bleeding on probing, total and differential white blood cells counts, lipid profiles, cytokine levels, and antibodies against oxidized LDL are also determined and compared over time. Before the treatment, the ZS experimental results reveal that the LDL particles of these patients are heavily modified. Only after 12 months of the periodontal treatment, the ZS results obtained reveal behavioral characteristics of healthy particles. This conclusion is also supported by complementary laboratorial analysis showing that the periodontal treatment induces systemic changes in several inflammatory markers.

Antioxidant status and biomarkers of oxidative stress in bovine leukemia virus-infected dairy cows.

Bovine leukemia virus (BLV) is among the most widespread livestock pathogens in many countries. Despite advances in understanding the pathogenesis of this disease, little is known about the involvement of oxidative stress. Therefore, this study examined the antioxidant status and the markers of oxidative stress in BLV-infected dairy cows. BLV infection was associated with an increase in triacylglycerol levels, a decrease in glutathione peroxidase (GSH-Px) activity and a tendency toward lower superoxide dismutase activity in the infected animals. No significant difference was observed in other markers of oxidative stress (i.e., conjugated dienes, hydroperoxides and malondialdehyde) in the infected animals compared to controls. A novel method for the analysis of oxidative stress, Z-scan based on the measurement of the mean-value of θ in low density lipoprotein indicated that the infected animals had low-density lipoprotein particles that were slightly less modified than those from the healthy group. Thus, we conclude that BLV infection is associated with a selective decrease in GSH-Px activity without any alteration in the common plasma markers of oxidative stress.

Adaptive immunity is related to coronary artery disease severity after acute coronary syndrome in subjects with metabolic syndrome

Metabolic syndrome (MetS) is an inflammatory state associated with high coronary disease risk. Inflammation and adaptive immunity modulate atherosclerosis and plaque instability. We examined early changes in anti-oxidized low-density lipoprotein (LDL) (anti-oxLDL) autoantibodies (Abs) in patients with MetS after an acute coronary syndrome (ACS). Patients of both genders (n=116) with MetS were prospectively included after an acute myocardial infarction (MI) or hospitalization due to unstable angina. Anti-oxLDL Abs (IgG class) were assayed at baseline, three and six weeks after ACS. The severity of coronary disease was evaluated by the Gensini score. We observed a decrease in anti-oxLDL Abs titers (p<0.002 vs. baseline), mainly in males (p=0.01), in those under 65 y (p=0.03), and in subjects with Gensini score above median (p=0.04). In conclusion, early decrease in circulating anti-oxLDL Abs is associated with coronary disease severity among subjects with MetS.

Novel fluorescent probe for low density lipoprotein, based on the enhancement of Europium emission band.

We report here the observation of the enhancement of Europium-tetracycline complex emission in Low Density Lipoprotein (LDL) solutions. Europium emission band of tetracycline solution containing Europium (III) chloride hexahydrate was tested to obtain effective enhancement in the presence of native LDL and oxidized LDL. Europium emission lifetime in the presence of lipoproteins was measured, resulting in a simple method to measure the lipoproteins quantity in an aqueous solution at physiological pH. This method shows that the complex can be used as a sensor to determine the different states of native and oxidized LDL in biological fluids.

Effects of two lipid lowering therapies on immune responses in hyperlipidemic subjects

AIMS To compare the effects of two of the most effective lipid-lowering therapies with similar LDL-cholesterol reduction capacity on the innate and adaptive immune responses through the evaluation of autoantibodies anti-oxidized LDL (anti-oxLDL Abs) and electronegative LDL [LDL(-)] levels. MAIN METHODS We performed a prospective, randomized, open label study, with parallel arms and blinded endpoints. One hundred and twelve subjects completed the study protocol and received rosuvastatin 40 mg or ezetimibe/simvastatin 10/40 mg for 12 weeks. Lipids, apolipoproteins, LDL(-), and anti-oxLDL Abs (IgG) were assayed at baseline and end of study. KEY FINDINGS Main clinical and laboratory characteristics were comparable at baseline. Lipid modifications were similar in both treatment arms, however, a significant raise in anti-oxLDL Abs levels was observed in subjects treated with rosuvastatin (p=0.026 vs. baseline), but not in those receiving simvastatin/ezetimibe. (p=0.233 vs. baseline), thus suggesting modulation of adaptive immunity by a potent statin. Titers of LDL(-) were not modified by the treatments. SIGNIFICANCE Considering atherosclerosis as an immune disease, this study adds new information, showing that under similar LDL-cholesterol reduction, the choice of lipid-lowering therapy can differently modulate adaptive immune responses.

Serum levels of IgG antibodies against oxidized LDL and atherogenic indices in HIV-1-infected patients treated with protease inhibitors.

Abstract Background: Antibodies against low-density lipoproteins (LDLs) that have been oxidized are associated with development of atherosclerotic lesions. In individuals infected with human immunodeficiency virus type 1 (HIV-1) with or without therapy, dyslipidemia and increased cardiovascular risk are observed. Methods: Serum levels of IgG antibodies against oxidized LDLs (IgG anti-oxLDL Abs) were determined by assay in 151 HIV-1-infected patients. Of these, 42 patients did not receive anti-retroviral therapy (ART-naïve), whereas 109 received highly active anti-retroviral therapy (HAART) consisting of lopinavir/ritonavir (LOP/r; n=50), efavirenz (EFV; n=30) and nevirapine (NVP; n=29) associated with nucleoside reverse transcriptase inhibitors. HIV-1 seronegative individuals (n=43) participated in the study. The following parameters were quantified: total cholesterol and its fractions, atherogenic indices (AIs), apolipoproteins A1 and B100, high sensitivity C-reactive protein, CD4+ and CD8+ T cells, and HIV-1-RNA. Results: Levels of IgG anti-oxLDL Abs were significantly higher (p<0.05) in the LOP/r group compared with the EFV and/or NVP and the seronegative group: median 0.32 (0.15, 0.58; 95% confidence interval) vs. 0.25 (0.13, 0.53) vs. 0.18 (0.04, 0.38), respectively. HIV-1-infected ART-naïve patients (n=42) presented antibodies levels similar to those observed for the LOP/r group, 0.33 (0.13, 0.63; p>0.05). The levels of IgG anti-oxLDL Abs correlated with an increase in AIs (r=0.216; p=0.036) and triglycerides (r=0.220; p=0.044) in the LOP/r group, and AIs in the ART-naïve group (r=0.300; p=0.046). Conclusions: Patients treated with LOP/r showed higher levels of IgG anti-oxLDL Abs compared with patients treated with EFV or NVP regimens, and these levels were associated with an increase in AIs.