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.

Cardiovascular disease parameters in periodontitis.

BACKGROUND: Recently, there has been an increasing in the impact of oral health on atherosclerosis and subsequent cardiovascular disease. The aim of this study is to investigate the association between chronic periodontitis and cardiovascular risk markers. METHODS: Forty patients with periodontitis and 40 healthy gender-, body mass index-, and age-matched individuals were compared by measuring total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, levels of cytokines, antibodies against oxidized low-density lipoprotein, thiobarbituric acid reactive substances, total and differential white blood cell counts, and the non-linear index of refraction. RESULTS: The levels of triglycerides and high-density lipoprotein in periodontitis patients were significantly higher and lower, respectively (P = 0.002 and P = 0.0126), compared to controls. Total cholesterol, low-density lipoprotein, and lipid peroxide levels were the same in both groups (P = 0.2943, P = 0.1284, and P = 0.067, respectively). Interleukin (IL)-6 and -8, antibodies against oxidized low-density lipoprotein, and leukocyte and neutrophil counts were significantly higher in periodontitis patients (P <0.05). The value of the non-linear index of refraction of low-density lipoprotein solutions was higher in the controls (P = 0.015) compared to individuals with periodontitis. CONCLUSION: Our results confirmed and further strengthened the suggested association between coronary artery disease and periodontitis.

Non-linear Optical Responses of Low-Density Lipoprotein are Associated with Intima-Media Thickness of Carotid Artery in Athletes.

We investigated the association between the degree of oxidative modification of LDL particles by non-linear optical response of LDL (Z-scan technique) and the presence of subclinical atherosclerosis in different segments of the carotid artery. We recruited high-intensity athlete runners (n = 44) and controls (n = 51) to participate in the study. The carotid intima-media thickness (cIMT), interleukin 10 (IL-10), TNF-alpha, and the non-linear optical responses of LDL particle (Z-scan) were assessed. In athletes, the mean cIMT differed between genders, with higher values observed in female athletes compared to male athletes (P < 0.05). Higher mean values for cIMT were seen in the right carotid arteries of female athletes as compared to female controls (P < 0.05). Higher levels of TNF-alpha and IL-10 were found in athletes (P < 0.05). Yet, ΔΓpv (transmittance curve) of Z-scan in athletes was higher than in the non-athletes, indicating less oxidation in LDL particles of athletes (P < 0.05). There was an inverse association between the ΔΓpv and cIMT in the right internal carotid segments (ß = -0.163, P < 0.05) in all subjects, and between the VO2max and the mean cIMT (ß = -0.003, P < 0.05) in male subjects. The present study shows that the Z-scan technique enabled to detect less oxidative modifications in LDL particles from athletes. This effect was associated with cIMT in a gender-dependent mode.

Antihypertensive therapy increases natural immunity response in hypertensive patients.

AIMS: The aim of this work was to evaluate the effects of treatment of hypertension on the autoantibodies to apolipoprotein B-derived peptides (anti-ApoB-D peptide Abs) response, inflammation markers and vascular function. MAIN METHODS: Eighty-eight patients with hypertension (stage 1 or 2) were recruited and advised to receive perindopril (4mg), hydrochlorothiazide (25mg), or indapamide (1.5mg) for 12weeks in a blinded fashion. Office and 24-h ambulatory blood pressure monitoring (24h ABPM), flow-mediated dilatation (FMD), nitrate-induced dilatation (NID), titers of IgG and IgM anti-ApoB-D peptide Abs, hsCRP, and interleukins (IL-8 and IL-10) were evaluated at baseline and 12weeks after therapies. KEY FINDINGS: All treatments reduced office BP, and improved FMD (P<0.05 vs. baseline). The NID was improved only in the perindopril arm (P<0.05 vs. baseline). The 24h-ABPM was reduced with perindopril and hydrochlorothiazide therapies (P<0.05 vs. baseline), but not with indapamide, and this effect was followed by increase in titers of IgM Anti-ApoB-D peptide Abs (P<0.05 vs. baseline), without modifications in titers IgG Anti-ApoB-D peptide Abs and interleukins. Multivariable regression analysis has shown that change in the titers of IgM anti-ApoB-D peptide was associated with the changes in FMD (ß -0.347; P<0.05). SIGNIFICANCE: These findings shed light to a possible modulator effect of the antihypertensive therapy on the natural immunity responses and vascular function.

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.

Obesity modulates the immune response to oxidized LDL in hypertensive patients.

Obesity and hypertension have been recognized as inflammatory diseases capable of activating the immune system, thus contributing to an increased cardiovascular risk. However, the link between adaptive immunity, obesity, and hypertension is poorly understood. We investigated the relationship of the body mass index (BMI) on the inflammatory, vascular, and immune responses in patients with hypertension naïve of anti-hypertensive treatment. Hypertensive patients (N = 88) were divided into three groups: normal weight (NW), overweight (OW), and obese (OB) subjects. Anti-oxidized LDL autoantibodies (anti-oxLDL Abs), anti-ApoB-D peptide (anti-ApoB-D) Abs, interleukin (IL)-8 and IL-10, flow-mediated dilation (FMD) of the brachial artery, and 24-h ambulatory blood pressure monitoring (ABPM) were assessed. OB patients presented lower levels of anti-oxLDL Abs and IL-10, higher levels of IL-8, and impaired FMD, when compared to NW and OW (P < 0.05), without differences between groups regarding anti-ApoB-D Abs. After adjusting for age, systolic and diastolic blood pressure, anti-oxLDL Abs were inversely correlated with BMI and waist circumference (r = -0.24, P = 0.02 and r = -0.25, P = 0.02, respectively), whereas ApoB-D correlated with 24-h ABPM (r = 0.22, P = 0.05 for systolic, and r = 0.29, P = 0.01 for diastolic blood pressure). Regression analyses showed inverse associations of anti-oxLDL Abs with BMI (ß = -0.05, P = 0.01) and waist circumference (ß = -0.01, P = 0.02); anti-ApoB-D Abs were associated with systolic and diastolic 24-h ABPM (ß = 0.96, P = 0.04; ß = 1.02, P = 0.005, for systolic and diastolic 24-h ABPM, respectively). Among hypertensive patients, obesity modulates the immune and inflammatory milieu, determining an unfavorable balance of cytokines and reduction in titers of anti-oxLDL Abs. Twenty-four hour ABPM is associated with titers of anti-ApoB-D Abs.

Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique.

Modifications in low-density lipoprotein (LDL) have emerged as a major pathogenic factor of atherosclerosis, which is the main cause of morbidity and mortality in the western world. Measurements of the heat diffusivity of human LDL solutions in their native and in vitro oxidized states are presented by using the Z-Scan (ZS) technique. Other complementary techniques were used to obtain the physical parameters necessary to interpret the optical results, e.g., pycnometry, refractometry, calorimetry, and spectrophotometry, and to understand the oxidation phase of LDL particles. To determine the sample's thermal diffusivity using the thermal lens model, an iterative one-parameter fitting method is proposed which takes into account several characteristic ZS time-dependent and the position-dependent transmittance measurements. Results show that the thermal diffusivity increases as a function of the LDL oxidation degree, which can be explained by the increase of the hydroperoxides production due to the oxidation process. The oxidation products go from one LDL to another, disseminating the oxidation process and caring the heat across the sample. This phenomenon leads to a quick thermal homogenization of the sample, avoiding the formation of the thermal lens in highly oxidized LDL solutions.

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.

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.

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.

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.