Alterations in lipoprotein defense against oxidative stress in metabolic syndrome

Alopecia Areata: A Review of the Role of Oxidative Stress, Possible Biomarkers, and Potential Novel Therapeutic Approaches

Alopecia areata (AA) is a dermatological condition characterized by non-scarring hair loss. Exact etiopathogenesis of AA is still unknown although it is known that several factors contribute to the collapse of the hair-follicle (HF)-immune-privileged (IP) site. Oxidative stress (OS) plays an important role in skin diseases. The aim of this review was to clarify the role of OS in AA pathogenesis and diagnosis, and to discuss potential treatment options. Oxidative-stress markers are altered in serum and skin samples of patients with AA, confirming a general pro-oxidative status in patients with AA. OS induces MHC class I chain-related A (MICA) expression in HF keratinocytes that activates the receptor NKG2D, expressed in NK cells and CD8+ T cytotoxic cells leading to destabilization of the HF immune-privileged site through the production of IFN-γ that stimulates JAK1 and JAK2 pathways. OS also activates the KEAP1-NRF2 pathway, an antioxidant system that contributes to skin homeostasis. In addition, a decrease of ATG5 and LC3B in the hair matrix and an increase in p62 levels indicates a reduction of intrafollicular autophagy during the evolution of AA. Potential biomarkers of OS in AA could be: malondialdehyde (MDA), advanced glycation end-products (AGEs), and ischemic-modified albumin (IMA). JAK inhibitors are the new frontier in treatment of AA and the use of nutraceuticals that modulate the OS balance, in combination with standard treatments, represent promising therapeutic tools.

Oxidative stress and antioxidant markers in patients with alopecia areata: A comparative cross-sectional study

Background

Alopecia areata is a chronic inflammatory skin disease. Oxidative stress may contribute to the pathogenesis of this condition.

Aim

To evaluate the serum oxidative stress markers and antioxidant capacity in patients with alopecia areata.

Methods

This cross-sectional study was performed on 40 patients with alopecia areata and 40 healthy controls. The fasting blood sugar, C-reactive protein, lipid profile, and serum oxidative markers, including advanced glycation end products and advanced oxidation protein products, were measured in this study. Also, antioxidant enzymes, including paraoxonase-1, lecithin-cholesterol acyltransferase and serum ferric-reducing antioxidant power, were determined.

Results

The serum levels of advanced glycation end products and advanced oxidation protein products were significantly higher in patients with alopecia areata, compared to the controls (P < 0.001), whereas the levels of ferric-reducing antioxidant power, paraoxonase-1 and lecithin-cholesterol acyltransferase were significantly lower in patients with alopecia areata, compared to the controls (P < 0.001). The mean fasting blood sugar level was significantly higher in patients with alopecia areata, compared to the controls. The ferric reducing antioxidant power level was significantly associated with the percentage of hair loss (P = 0.01, r = 0.4) and the serum C-reactive protein level (P = 0.03, r = -0.3) in patients with alopecia areata.

Limitations

Since the current study had a cross-sectional design, no cause-effect relationship was established between alopecia areata and oxidative stress. The sample size of our study was also small.

Conclusion

Based on the present results, the oxidant-antioxidant enzymatic system is impaired in alopecia areata due to the increased oxidative products and decreased antioxidant activity.

Proatherogenic Sialidases and Desialylated Lipoproteins: 35 Years of Research and Current State from Bench to Bedside

This review summarizes the main achievements in basic and clinical research of atherosclerosis. Focusing on desialylation as the first and the most important reaction of proatherogenic pathological cascade, we speak of how desialylation increases the atherogenic properties of low density lipoproteins and decreases the anti-atherogenic properties of high density lipoproteins. The separate sections of this paper are devoted to immunogenicity of lipoproteins, the enzymes contributing to their desialylation and animal models of atherosclerosis. In addition, we evaluate the available experimental and diagnostic protocols that can be used to develop new therapeutic approaches for atherosclerosis.

Activity of Lipoprotein-Associated Enzymes in Indigenous Children Living at Different Altitudes

BACKGROUND

High altitude is associated with hypobaric hypoxia, and metabolic modifications. In particular, alterations to lipoprotein-associated enzymes have been reported under hypoxia.

OBJECTIVE

To determine the association between paraoxonase 1 (PON-1) and Cholesteryl-ester transfer protein (CETP) activities and altitude in two groups of Argentinean Indigenous schoolchildren living at different altitudes.

METHODS

A cross-sectional study compared 151 schoolchildren from San Antonio de los Cobres (SAC), 3,750 m, with 175 schoolchildren from Chicoana (CH), 1,400 m. Anthropometric data, lipids, apolipoprotein (apo) A-I, apo B, plus PON-1 and CETP activities were determined.

RESULTS

The prevalence of overweight/obesity was significantly lower in SAC than in CH. Z- BMI (0.3 vs 0.7), Apo A-I/Apo B (1.67 vs. 1.85) and PON-1 (170 vs. 243 nmol/mL.min) were significantly lower in SAC than in CH, respectively. Total cholesterol (156 vs 144 mg/dL), triglycerides (TG) (119 vs. 94 mg/dL), apo A-I (133 vs. 128 mg/dL), apo B (84 vs. 73 mg/dL), hematocrit (48 vs. 41%), transferrin (295 vs. 260 mg/dL) and CETP (181 vs. 150%/mL.h) were significantly higher in SAC than in CH. There was a significant univariate association between altitude and transferrin (r0.38), hematocrit (r0.75), TG (r0.24), apo B (r0.29), PON-1 (r-0.40), and CETP (r0.37). Multiple linear regression analyses showed that altitude was significantly associated with children's TG (β = 0.28, R² = 0.14), HDL-C (β = ‒0.27; R² = 0.23), apo B (β = 0.32; R² = 0.14), CETP (β = 0.38; R² = 0.15) and PON-1 (β = ‒0.36; R² = 0.16), adjusted for age, gender and BMI.

CONCLUSION

SAC children presented a more atherogenic lipid profile, plus lower PON1 and higher CETP activities, than CH children.

Poor glycemic control in type 2 diabetes enhances functional and compositional alterations of small, dense HDL3c

High-density lipoprotein (HDL) possesses multiple biological activities; small, dense HDL3c particles displaying distinct lipidomic composition exert potent antiatherogenic activities which can be compromised in dyslipidemic, hyperglycemic insulin-resistant states. However, it remains indeterminate (i) whether such functional HDL deficiency is related to altered HDL composition, and (ii) whether it originates from atherogenic dyslipidemia, dysglycemia, or both. In the present work we analyzed compositional characteristics of HDL subpopulations and functional activity of small, dense HDL3c particles in treatment-naïve patients with well-controlled (n=10) and poorly-controlled (n=8) type 2 diabetes (T2D) and in normolipidemic age- and sex-matched controls (n=11). Our data reveal that patients with both well- and poorly-controlled T2D displayed dyslipidemia and low-grade inflammation associated with altered HDL composition. Such compositional alterations in small, dense HDL subfractions were specifically correlated with plasma HbA1c levels. Further analysis using a lipidomic approach revealed that small, dense HDL3c particles from T2D patients with poor glycemic control displayed additional modifications of their chemical composition. In parallel, antioxidative activity of HDL3c towards oxidation of low-density lipoprotein was diminished. These findings indicate that defective functionality of small, dense HDL particles in patients with T2D is not only affected by the presence of atherogenic dyslipidemia, but also by the level of glycemic control, reflecting compositional alterations of HDL.

Lifestyle intervention enhances high-density lipoprotein function among patients with metabolic syndrome only at normal low-density lipoprotein cholesterol plasma levels

BACKGROUND

Metabolic syndrome (MetS) is associated with altered lipoprotein metabolism and impairment in the functionality of small, dense high-density lipoprotein (HDL) particles secondary to compositional alterations.

OBJECTIVE

The objective of this study was to investigate the capacity of a lifestyle program to improve the composition and antioxidative function (AOX) of small dense HDL3c in MetS.

METHODS

Patients with MetS (n = 33) not taking lipid-lowering drugs were recruited to follow a 12-week educational program to reduce caloric intake and to increase physical activity. HDL subfractions were preparatively isolated by isopycnic density-gradient ultracentrifugation. AOX of HDL3c was assessed as its capacity to inhibit low-density lipoprotein oxidation induced by an azoinitiator.

RESULTS

AOX of HDL3c was significantly improved (mean reduction in the propagation rate of low-density lipoprotein oxidation by HDL3c, -6.8%, P = .03) and systemic oxidative stress, assessed as plasma levels of 8-isoprostanes, tended to decrease in normocholesterolemic MetS patients (low-density lipoprotein cholesterol [LDL-C] < 130 mg/dL) but not in patients with elevated LDL-C levels and in the whole study population. In both the whole study population and the normocholesterolemic subgroup, lifestyle intervention resulted in a significant degree of normalization of HDL3c composition, (enrichment in apolipoprotein A-I and cholesteryl esters, depletion in triglycerides), which was more pronounced at LDL-C < 130 mg/dL.

CONCLUSION

In patients with MetS, a lifestyle program improves AOX of small, dense HDL in subjects with normal LDL-C levels. Correction of HDL composition, involving partial normalization of apoA-I content and core lipid composition, 2 central features of the lipid hydroperoxide-inactivating capacity of HDL, may account for this effect.

Antioxidant properties of high-density lipoproteins are impaired in women with polycystic ovary syndrome

OBJECTIVE

To determine the relationships among the inflammatory index, intrinsic oxidation levels, lipid and apolipoprotein (apo)A-I concentrations of high-density lipoprotein (HDL), and polycystic ovary syndrome (PCOS).

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENT(S)

A total of 425 patients with PCOS and 441 control women were included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The HDL inflammatory index (HII) was determined using a cell-free fluorometric assay. Intrinsic HDL oxidation levels, HDL-free cholesterol, HDL-cholesterol ester, HDL-triglyceride, serum apoA-I, and malondialdehyde levels were also measured.

RESULT(S)

The mean HII value and the frequency of HII ≥1 were significantly higher in the PCOS group (0.77 ± 0.54, 27.1%) than in the control group (0.53 ± 0.37, 8.4%). These values were also higher in each of the 4 PCOS phenotypes based on the Rotterdam criteria than in the controls, and higher in patients with hyperandrogenism (HA) + oligo- and/or anovulation (OA) phenotype than in those with OA + polycystic ovary (PCO) phenotype. Furthermore, patients with PCOS with OA + PCO had lower malondialdehyde and intrinsic HDL oxidation levels compared with those with HA. Multivariate regression analysis demonstrated that PCOS, HDL-cholesterol ester, and E2 levels were the main predictors of HII value.

CONCLUSION(S)

The impairment of HDL antioxidant/anti-inflammatory function in PCOS is related to HA status, increased oxidative stress, and abnormalities in HDL components and thus may contribute to PCOS pathogenesis and increase the risks of future cardiovascular diseases.

Oxidative stress in phenylketonuria: future directions

Phenylketonuria represents the most prevalent inborn error of amino acid metabolism. In early diagnosed patients adequate and continued dietary treatment results in a good neurologic outcome. Natural protein and phenylalanine-restricted diet, even if rich in fruits and vegetables, represents a serious risk for nutritional deficiencies, albeit universally accepted. In the last few years, a growing number of reports have been describing oxidative stress as a concern in phenylketonuric patients. The diet itself includes good sources of dietary antioxidants (phytochemicals, some vitamins and minerals) but also a risk factor for some deficiencies (selenium, zinc, ubiquinone-10 and L-carnitine). Additionally, the extreme stringency of the diet may impose a reduced synthesis of endogenous antioxidants (like ubiquinone-10 and glutathione). Furthermore, increased phenylalanine levels, and its metabolites, may enhance the endogenous synthesis of reactive species and free radicals and/or interfere with the endogenous synthesis of enzymatic antioxidants (like glutathione peroxidase). Therefore, oxidative stress will probably increase, mainly in late diagnosed patients or in those with bad metabolic control. Considering the known association between oxidative stress, obesity and cardiovascular disease, it seems advisable to look further to the impact of oxidative stress on body macromolecules and structures (like lipoprotein oxidation), especially in phenylketonuric patients with late diagnosis or bad metabolic control, in order to prevent future increased risks. Recommendations for PKU patient's clinical follow-up improvement and educational goals are included.

Lipid packing determines protein-membrane interactions: challenges for apolipoprotein A-I and high density lipoproteins

Protein and protein-lipid interactions, with and within specific areas in the cell membrane, are critical in order to modulate the cell signaling events required to maintain cell functions and viability. Biological bilayers are complex, dynamic platforms, and thus in vivo observations usually need to be preceded by studies on model systems that simplify and discriminate the different factors involved in lipid-protein interactions. Fluorescence microscopy studies using giant unilamellar vesicles (GUVs) as membrane model systems provide a unique methodology to quantify protein binding, interaction, and lipid solubilization in artificial bilayers. The large size of lipid domains obtainable on GUVs, together with fluorescence microscopy techniques, provides the possibility to localize and quantify molecular interactions. Fluorescence Correlation Spectroscopy (FCS) can be performed using the GUV model to extract information on mobility and concentration. Two-photon Laurdan Generalized Polarization (GP) reports on local changes in membrane water content (related to membrane fluidity) due to protein binding or lipid removal from a given lipid domain. In this review, we summarize the experimental microscopy methods used to study the interaction of human apolipoprotein A-I (apoA-I) in lipid-free and lipid-bound conformations with bilayers and natural membranes. Results described here help us to understand cholesterol homeostasis and offer a methodological design suited to different biological systems.

Oxidative stress and metabolic changes after continuous positive airway pressure treatment according to previous metabolic disorders in sleep apnea-hypopnea syndrome patients

Sleep apnea-hypopnea syndrome (SAHS) is characterized by recurrent episodes of hypoxia/reoxygenation, which seems to promote oxidative stress. SAHS patients experience increases in hypertension, obesity, and dyslipidemia, and the oxidative state has been related to the genesis of these disorders. The purpose of this study was to examine the changes in oxidative stress markers and metabolic parameters in S AHS patients after 1 month of treatment with continuous positive airway pressure (CPAP), in relation to their previous metabolic disorders. The study included 78 SAHS patients who required CPAP. The patients were classified according to their disorders, including hypertension, obesity, and dyslipidemia. Measurements were made before and after 1 month of treatment with CPAP. The diastolic blood pressure decreased after treatment in all the patients, significantly so in those who were nondyslipidemic, obese, or hypertensive (the systolic pressure also fell in these latter patients). Plasma oxidative stress biomarkers showed a significant antioxidant capacity and increased activity (P<0.05) after treatment, more so in the nondyslipidemic and hypertensive patients. Furthermore, serum lipid peroxidation levels decreased after CPAP (P<0.01). No change was observed in insulin resistance (IR) after CPAP treatment in any of the different disorders. In conclusion, oxidative stress markers improved significantly after CPAP treatment in SAHS patients, especially in the nondyslipidemic and hypertensive patients. Moreover, the blood pressure decreased after CPAP treatment, particularly in the obese, nondyslipidemic, and hypertensive patients. No significant change in IR was found in any of the SAHS patients after CPAP treatment.

Relationship between the diagnostic components of metabolic syndrome (MS) and cognition by ApoE genotype in the elderly

The purpose of this study was to find out the effect of the ApoE genotype on the relationship between metabolic syndrome (MS) and its diagnostic components and cognitive impairment in the elderly. A total of 2944 subjects aged over 60 years were analyzed from the data of Gwangju Dementia and Mild Cognitive Impairment Study. We examined demographic characteristics, current and past illness history, drug history, Korean version-mini-mental state examination (K-MMSE). We also examined ApoE genotype and analyzed associated factors with MS. The MS was present in 53.8% of the subjects (36.8% of men and 61.1% of women). On multiple logistic regression analysis, MS was not associated with the cognitive impairment (K-MMSE score <18) adjusted for age, sex, and educational level. The interactive effect between systolic and diastolic blood pressure (SBP, and DBP, respectively) and ApoE on cognition was not significant (all p>0.3), but the interactive effect between triglyceride (TG), high-density-lipoprotein-cholesterol (HDLc) and ApoE on cognition was significant after adjustment for age, sex, and education (B=-0.285, Wald=4.194, p=0.041; B=0.372, Wald=4.134, p=0.042). These results suggest that blood TG and HDLc may affect cognitive function in the elderly in the presence of ApoE varepsilon4 allele.

Alterations in the high density lipoprotein phenotype and HDL-associated enzymes in subjects with metabolic syndrome

Patients with metabolic syndrome (MetS) usually have low high density lipoprotein cholesterol (HDL-C) levels. We determined the HDL distribution profile as well as the HDL-related lipoprotein associated phospholipase A(2) (HDL-LpPLA(2)) and paraoxonase-1 (PON1) activities in subjects with MetS (n = 189) but otherwise healthy. Age and sex-matched individuals (n = 166) without MetS served as controls. The lower HDL-C concentration in MetS patients was due to a reduction in both large and small HDL subclasses (P < 0.001 and P < 0.05, respectively). As the number of MetS components increased, the HDL phenotype comprised of a greater percentage of small HDL-3 and less large HDL-2 subclasses, resulting in a decreased HDL-2/HDL-3 ratio (P < 0.001 for all trends). Multivariate analysis revealed that HDL-2 levels and the HDL-2/HDL-3 ratio significantly and independently correlated with HDL-C (positively) and TG (negatively) levels. HDL-3 concentration significantly and independently positively correlated with HDL-C and TG levels. HDL-LpPLA(2) activity was decreased in MetS patients (P < 0.01), a phenomenon that may contribute to the defective antiatherogenic activity of HDL in MetS. PON1 activity did not differ between groups. We conclude that MetS, in addition to the decrease in HDL-C concentration, is associated with alterations in the HDL phenotype, which is comprised of a greater percentage of small HDL subclasses. Furthermore, HDL-LpPLA(2) activity is decreased in MetS patients.