Alterations of high density lipoprotein subclasses in obese subjects

A new risk factor for coronary artery disease can be detected by an ApoA1 mAb-based assay

BACKGROUND

This study aimed to find coronary artery disease (CAD) related apolipoprotein A1 (ApoA1) monoclonal antibody (mAb) and to evaluate the diagnostic value of the assay based on it.

METHODS

Patients with CAD diagnosed by coronary angiography (disease group, n = 180) and healthy subjects (control group, n = 199) were recruited. The correlation between methods and CAD were evaluated by Spearman's rank correlation coefficients. Receiver operating characteristic (ROC) curve analysis was used to evaluate the auxiliary diagnostic value of methods for CAD. Odds ratios (ORs) of the test results in CAD were estimated using logistic regression analysis.

RESULTS

Measurements from an ApoA1 mAb were found significantly positively correlated with CAD (r = 0.243, P < 0.01), unlike the measurements from the ApoA1 pAb were negatively correlated with CAD (r = -0.341, P < 0.001). The areas under the ROC curve of the ApoA1 mAb and pAb measurements were 0.704 and 0.563, respectively, in patients with normal HDL-C levels. ApoA1 values from the mAb assay had a significant positive impact on CAD risk.

CONCLUSION

An ApoA1 mAb-based assay can distinguish a high-density lipoprotein (HDL) subclass positively related to CAD, which can be used to improve and reappraise CAD risk assessment.

Impaired HDL-associated enzymes and proteins in children and adolescents with weight disorders and their association with novel cardiometabolic indexes

BACKGROUND AND AIMS

Overweight/obesity (OW/OB) is associated with modifications in lipoprotein (Lp)-associated enzymes and proteins, such as cholesteryl ester transfer protein (CETP), Lp-associated phospholipase A2 (LpPLA2) and paraoxonase (PON)1. No evidence is available regarding underweight (UW). The following indexes have been proposed to better assess atherogenic risk related to weight alterations: triglycerides-glucose index (TyG), visceral adiposity index (VAI) and height-corrected lipid accumulation product (HLAP).

AIM

To analyze the presence of alterations in Lp-associated enzymes and proteins in children and adolescents with UW and OW/OB and their relation to novel cardiometabolic indexes.

METHODS AND RESULTS

Thirty male children and adolescents with UW, 66 with normal weight (NW) and 30 with OW/OB were included. Anthropometric parameters, glucose, Lp profile and the activities of CETP, LpPLA2 and PON1 were evaluated. Body mass index (BMI)-z, TyG, VAI and HLAP were calculated. UW and NW showed lower CETP activity than OW/OB (Mean ± SD) (218 ± 38vs.224 ± 26vs.237 ± 26%/mL.h; p < 0.05). UW and OW/OB showed lower PON1 activity than NW (318 ± 170vs.409 ± 200vs.310 ± 184 nmol/mL.min; p < 0.05). TyG was higher in OW/OB than UW (p < 0.01), whilst both HLAP (p < 0.05) and VAI (p < 0.01) followed a linear trend across weight categories. After adjusting for age and BMI-z, TyG was an independent predictor of CETP (r2 = 0.25, β = -0.22, p < 0.01) and LpPLA2 (r2 = 0.21,β = -0.21,p < 0.05), while VAI (r2 = 0.21,β = -0.32,p < 0.01) and HLAP (r2 = 0.20,β = -0.31,p < 0.01) of CETP.

CONCLUSIONS

Both UW and OW/OB showed impaired antioxidant PON1 activity. Moreover, TyG, VAI and HLAP were all capable of predicting alterations in crucial modulators of Lp metabolism and vascular inflammation in children and adolescents with varying degrees of alterations in body weight.

HDL in Atherosclerotic Cardiovascular Disease: In Search of a Role

For a long time, high-density lipoprotein cholesterol (HDL-C) has been regarded as a cardiovascular disease (CVD) protective factor. Recently, several epidemiological studies, while confirming low plasma levels of HDL-C as an established predictive biomarker for atherosclerotic CVD, indicated that not only people at the lowest levels but also those with high HDL-C levels are at increased risk of cardiovascular (CV) mortality. This “U-shaped” association has further fueled the discussion on the pathophysiological role of HDL in CVD. In fact, genetic studies, Mendelian randomization approaches, and clinical trials have challenged the notion of HDL-C levels being causally linked to CVD protection, independent of the cholesterol content in low-density lipoproteins (LDL-C). These findings have prompted a reconsideration of the biological functions of HDL that can be summarized with the word “HDL functionality”, a term that embraces the many reported biological activities beyond the so-called reverse cholesterol transport, to explain this lack of correlation between HDL levels and CVD. All these aspects are summarized and critically discussed in this review, in an attempt to provide a background scenario for the “HDL story”, a lipoprotein still in search of a role.

HDL Subclass Distribution Shifts with Increasing Central Adiposity

Although cross-sectional studies have shown that obesity is associated with lower concentrations of large high-density lipoprotein (HDL) subclasses, it is unknown if changes in HDL subclasses are related to changes in body fat and its distribution over time. We therefore assessed changes in HDL subclass distribution over a 5.5-year free-living follow-up period in 24 black South African women. At baseline and follow-up, body composition and body fat distribution were measured using anthropometry, dual X-ray absorptiometry, and computerized tomography. HDL subclass distribution was quantified using Lipoprint®. Over the 5.5-year follow-up period, body fat (+17.3 ± 4.5 kg, p < 0.05) and trunk fat mass (+7.4 ± 1.9%, % fat mass, FM, p < 0.05) increased, while leg fat mass (-2.53 ± 0.56%, % FM, p < 0.001) and the distribution of large (-6.43 ± 2.12%, p < 0.05) HDL subclasses decreased. A percentage decrease in large HDL subclasses was associated with a percentage increase in central fat mass (visceral adipose tissue (VAT) area, p < 0.05) and a percentage decrease in peripheral fat mass (leg fat mass). These preliminary findings suggest that a relative redistribution of body fat from the periphery to the abdominal region were associated with a decrease HDL subclass size in black South African women and provide a novel link between body fat distribution and lipidology in this population.

Insulin Resistance Predicts Atherogenic Lipoprotein Profile in Nondiabetic Subjects

BACKGROUND

Atherogenic diabetes is associated with an increased cardiovascular risk and mortality in diabetic individuals; however, the impact of insulin resistance (IR) in lipid metabolism in preclinical stages is generally underreported. For that, we evaluated the capacity of IR to predict an atherogenic lipid subfraction profile.

METHODS

Complete clinical evaluation and biochemical analysis (lipid, glucose profile, LDL, and HDL subfractions and LDL phenotype and size) were performed in 181 patients. The impact of IR as a predictor of atherogenic lipoproteins was tested by logistic regression analysis in raw and adjusted models.

RESULTS

HDL-C and Apo AI were significantly lower in individuals with IR. Individuals with IR had a higher percentage of small HDL particles, lower percentage in the larger ones, and reduced frequency of phenotype A (IR = 62%; non-IR = 83%). IR individuals had reduced probability to have large HDL (OR = 0.213; CI = 0.999-0.457) and had twice more chances to show increased small HDL (OR = 2.486; CI = 1.341-7.051). IR was a significant predictor of small LDL (OR = 3.075; CI = 1.341-7.051) and atherogenic phenotype (OR = 3.176; CI = 1.469-6.867).

CONCLUSION

IR, previously DM2 diagnosis, is a strong predictor of quantitative and qualitative features of lipoproteins directly associated with an increased atherogenic risk.

Association between ethnicity and obesity with high-density lipoprotein (HDL) function and subclass distribution

BACKGROUND

Obesity and low high-density lipoprotein-cholesterol (HDL-C) levels are associated with cardiovascular risk. Surprisingly, despite a greater prevalence of obesity and lower HDL concentrations than white women, black South African women are relatively protected against ischaemic heart disease.

METHODS

We investigated whether this apparent discrepancy may be related to different HDL function and subclass distribution in black and white, normal-weight and obese South African women (n = 40). HDL functionality was assessed by measuring paraoxonase (PON) activity, platelet activating factor acetylhydrolase (PAF-AH) activity, Oxygen Radical Absorbance Capacity (ORAC) and quantification of the expression of vascular cell adhesion molecule in endothelial cells. PON-1 and PAF-AH expression was determined in isolated HDL and serum using Western blotting. Levels of large, intermediate and small HDL subclasses were measured using the Lipoprint® system.

RESULTS

PON activity was lower in white compared to black women (0.49 ± 0.09 U/L vs 0.78 ± 0.10 U/L, p < 0.05), regardless of PON-1 protein levels. Obese black women had lower PAF-AH activity (9.34 ± 1.15 U/L vs 13.89 ± 1.21 U/L, p <0.05) and HDL-associated PAF-AH expression compared to obese white women. Compared to normal-weight women, obese women had lower large HDL, greater intermediate and small HDL; an effect that was more pronounced in white women than black women. There were no differences in antioxidant capacity or anti-inflammatory function across groups.

CONCLUSIONS

Our data show that both obesity and ethnicity are associated with differences in HDL functionality, while obesity was associated with decreases in large HDL subclass distribution. Measuring HDL functionality and subclass may, therefore, be important factors to consider when assessing cardiovascular risk.

Increased cholesterol efflux capacity in metabolic syndrome: Relation with qualitative alterations in HDL and LCAT

BACKGROUND

Metabolic syndrome (MetS) is associated with changes in HDL levels, composition and sub-fraction profile. Whether these alterations affect HDL anti-atherogenic function, specifically measured as its capacity to perform cholesterol efflux, is not yet clearly known.

OBJECTIVE

To evaluate the relation between serum cholesterol efflux capacity and the changes in HDL composition and sub-fraction profile in MetS.

METHODS

In 35 non-treated MetS patients and 15 healthy controls, HDL mediated cholesterol efflux was measured as the ability of apoB-depleted serum to accept cholesterol from cholesterol-loaded BHK cells expressing either ABCA1 or ABCG1. Additionally we determined: lipid profile, HDL sub-fractions (NMR) and LCAT mass (ELISA). Isolated HDL (δ:1.063-1.210 g/mL) was chemically characterized. Pre-β1-HDL was determined by 2D-electrophoresis in a sub-group of MetS and controls (n = 6 each).

RESULTS

Surprisingly, MetS patients presented higher ABCA1 mediated cholesterol efflux (10.4 ± 1.8 vs. 8.7 ± 0.3%; p = 0.0001), without differences in ABCG1 efflux. In MetS, HDL showed reduction in particle size and number (p < 0.02) and lower large/small HDL ratio (p = 0.05), as well as triglyceride enrichment (p = 0.0001). Pre-β1-HDL was increased in MetS (p = 0.048) and correlated with ABCA1-cholesterol efflux (r = 0.64; p = 0.042). LCAT mass showed a tendency to reduction in MetS (p = 0.08), and inversely correlated with ABCA1-cholesterol efflux (r = -0.51; p = 0.001), independently of obesity and insulin-resistance (β = -0.40, p = 0.034).

CONCLUSION

This is the first description of ABCA1 mediated cholesterol efflux in MetS. Regardless the reduced HDL-cholesterol, in vitro cholesterol efflux capacity by ABCA1 was enhanced, linked to increased pre-β1-HDL and slightly reduced in LCAT mass that would probably reflect a delay in reverse cholesterol transport occurring in MetS.

HDL and lifestyle interventions

The main lifestyle interventions to modify serum HDL cholesterol include physical exercise, weight loss with either caloric restriction or specific dietary approaches, and smoking cessation. Moderate alcohol consumption can be permitted in some cases. However, as these interventions exert multiple effects, it is often difficult to discern which is responsible for improvement in HDL outcomes. It is particularly noteworthy that recent data questions the use of HDL cholesterol as a risk factor and therapeutic target since randomised interventions and Mendelian randomisation studies failed to provide evidence for such an approach. Therefore, these current data should be considered when reading and interpreting this review. Further studies are needed to document the effect of lifestyle changes on HDL structure-function and health.

Obesity favors apolipoprotein E- and C-III-containing high density lipoprotein subfractions associated with risk of heart disease

Human HDLs have highly heterogeneous composition. Plasma concentrations of HDL with apoC-III and of apoE in HDL predict higher incidence of coronary heart disease (CHD). The concentrations of HDL-apoA-I containing apoE, apoC-III, or both and their distribution across HDL sizes are unknown. We studied 20 normal weight and 20 obese subjects matched by age, gender, and race. Plasma HDL was separated by sequential immunoaffinity chromatography (anti-apoA-I, anti-apoC-III, anti-apoE), followed by nondenaturing-gel electrophoresis. Mean HDL-cholesterol concentrations in normal weight and obese subjects were 65 and 50 mg/dl (P = 0.009), and total apoA-I concentrations were 119 and 118 mg/dl, respectively. HDL without apoE or apoC-III was the most prevalent HDL type representing 89% of apoA-I concentration in normal weight and 77% in obese (P = 0.01) individuals; HDL with apoE-only was 5% versus 8% (P = 0.1); HDL with apoC-III-only was 4% versus 10% (P = 0.009); and HDL with apoE and apoC-III was 1.5% versus 4.6% (P = 0.004). Concentrations of apoE and apoC-III in HDL were 1.5-2× higher in obese subjects (P ≤ 0.004). HDL with apoE or apoC-III occurred in all sizes among groups. Obese subjects had higher prevalence of HDL containing apoE or apoC-III, subfractions associated with CHD, whereas normal weight subjects had higher prevalence of HDL without apoE or apoC-III, subfractions with protective association against CHD.

High-density lipoprotein subfractions--what the clinicians need to know

Although the inverse relationship between plasma levels of high-density lipoprotein (HDL) and cardiovascular disease has been largely demonstrated, many observations have suggested that the assessment of HDL functionality might be more informative than a simple measurement of HDL-cholesterol plasma levels. HDLs are a class of structurally and functionally heterogeneous particles; in atherosclerosis-related diseases, changes in HDL subfraction levels and functions are frequently observed. Circulating levels of large HDL particles are decreased in dyslipidaemic conditions, while levels of small dense HDL particles are increased in patients with coronary heart disease. Furthermore, specific genetic defects in proteins involved in HDL metabolism significantly impact the distribution of HDL subpopulations. Finally, many drugs used for dyslipidaemia induce changes in HDL subfractions strictly related to cardiovascular disease. Although several methods exist to evaluate HDL subclass levels, most of them are not easily applicable in clinical practice, due to the costs and high variability. However, the possibility to measure the levels of specific HDL subfractions in patients with atherosclerosis-related diseases might help to better define their cardiovascular risk.

High-density lipoprotein subclass and particle size in coronary heart disease patients with or without diabetes

BACKGROUND

A higher prevalence of coronary heart disease (CHD) in people with diabetes. We investigated the high-density lipoprotein (HDL) subclass profiles and alterations of particle size in CHD patients with diabetes or without diabetes.

METHODS

Plasma HDL subclasses were quantified in CHD by 1-dimensional gel electrophoresis coupled with immunodetection.

RESULTS

Although the particle size of HDL tend to small, the mean levels of low density lipoprotein cholesterol(LDL-C) and total cholesterol (TC) have achieved normal or desirable for CHD patients with or without diabetes who administered statins therapy. Fasting plasma glucose (FPG), triglyceride (TG), TC, LDL-C concentrations, and HDL₃ (HDL(3b) and (3a)) contents along with Gensini Score were significantly higher; but those of HDL-C, HDL(2b+preβ2), and HDL(2a) were significantly lower in CHD patients with diabetes versus CHD patients without diabetes; The preβ₁-HDL contents did not differ significantly between these groups. Multivariate regression analysis revealed that Gensini Score was significantly and independently predicted by HDL(2a), and HDL(2b+preβ2).

CONCLUSIONS

The abnormality of HDL subpopulations distribution and particle size may contribute to CHD risk in diabetes patients. The HDL subclasses distribution may help in severity of coronary artery and risk stratification, especially in CHD patients with therapeutic LDL, TG and HDL levels.

The relationship between high density lipoprotein subclass profile and plasma lipids concentrations

HDL particles posses multiple antiatherogenic activities and the identification and differentiation of individual HDL subclasses may be useful in documentation and understanding of metabolic changes of different HDL subclasses. The major plasma lipids exist and are transported in the form of lipoprotein complexes. Hence, alterations in plasma lipids levels can interfere with the composition, content, and distribution of plasma lipoprotein subclasses that affect atherosclerosis risk. The research review major discussed the relationship between plasma lipids levels and HDL subclasses distribution. The general shift toward smaller size of HDL particle size in HTG, HCL and MHL subjects, and the changes were more prominent with the elevation of TG and TC levels which imply that HDL maturation might be abnormal and RCT pathway might be weaken, and these changes were more seriously in MHL subjects. Plasma contents of small sized HDL particles significantly higher, whereas those of large sized HDL particles were significantly lower with elevation of TG/HDL-C and TC/HDL-C ratios. Increased in the TC/HDL-C ratio alone did not influence the distributions of HDL subclasses significantly when the TG/HDL-C ratio was low (TG/HDL-C ≤ 2.5). Hence, the TG/HDL-C ratio might be more sensitive to reflect the alteration of HDL subclass distribution than the TC/HDL-C ratio. In LDL-C/HDL-C ≤ 2.3 group, the pattern of distribution in HDL subclass was in agreement with the normolipidemic subjects. Moreover, considering the relative ease of measuring TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios, as opposed to measuring HDL subclasses, these 3 ratios together may be a good indicator of HDL subclass distribution. The protective effect of increased apoA-I levels against the reduction of HDL_2b caused by elevated TG concentration. On one hand, plasma HDL-C and apoA-I appear to play a coordinated role in the assembly of HDL particles and the determination of their contents among the total subjects. On the other hand, the apoA-I level might be a more powerful factor than HDL-C to influence the distribution of HDL subclasses in hyperlipidemic subjects. At the same time, from point of HDL subclasses distribution, the plasma lipids, apos concentrations and apos ratios should be considered while assessing the CHD risk. Abnormality of HDL subclasses distribution may result in accelerated atherosclerosis, therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and distribution of HDL particles is the target of innovative pharmacological approaches to large-sized HDL particles rising, including enhanced apoA-I levels.

Reduced high-density lipoprotein 2b in non-obese type 2 diabetic patients analysed by a microfluidic chip method in a case-control study

BACKGROUND

Alterations in high-density lipoprotein (HDL) subfractions, especially in the HDL2b subfraction, have been reported in type 2 diabetes mellitus (T2DM). However, new methods for convenient and reliable quantitation of HDL2b are yet to be developed.

METHODS

Thirty-eight patients with T2DM were enrolled and age-, sex- and body mass index (BMI)-matched controls were selected from the same population. A microfluidic chip method was employed to analyse serum HDL subfractions.

RESULTS

The microfluidic chip method revealed a significant reduction in HDL2b and its ratio to total HDL in T2DM patients. There was a reverse correlation for total HDL and HDL2b, and its ratio with triglycerides, homeostasis model assessment-insulin sensitivity index (HOMA-IS) and insulin resistance index (HOMA-IR).

CONCLUSIONS

We have shown a reduction of HDL2b and its ratio to total HDL by a novel chip method in T2DM patients. The significant correlation between HDL2b and HOMA-IS and HOMA-IR may have further predictive value in clinical utility.

Relationship between apolipoprotein C-III concentrations and high-density lipoprotein subclass distribution

High-density lipoprotein (HDL) subclasses have different antiatherogenic potentials and functional properties. This work presents our findings and discussions on their metabolic implications on apolipoprotein (apo) C-III together with other apolipoprotein levels and HDL subclass distribution profile. Apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis coupled with immunodetection in 511 subjects. Concentrations of triglycerides and of apo B-100, C-II, and C-III were higher, whereas those of HDL cholesterol were lower, for subjects in the highest tertile of apo C-III levels group, which presented a typical hypertriglyceridemic lipid profile. Subjects in the middle and highest tertile of apo C-III levels groups had increased prebeta(1)-HDL, HDL(3c), HDL(3b) (only in the highest tertile of apo C-III group), and HDL(3a), but decreased HDL(2a) and HDL(2b) contents compared with subjects in the lowest tertile of apo C-III levels group. With the elevation of apo C-III together with apo C-II levels, contents of small-sized prebeta(1)-HDL increased successively and significantly; but those of large-sized HDL(2b) reduced successively and significantly. With a rise in apo C-III and apo A-I levels, those of prebeta(1)-HDL increased significantly. Moreover, subjects with high apo A-I levels showed a substantial increase in HDL(2b); on the contrary, HDL(2b) declined progressively and obviously for subjects in the low apo A-I levels with the elevation of apo C-III levels. Correlation analysis illustrated that apo C-III levels were positively associated with prebeta(1)-HDL, prebeta(2)-HDL, and HDL(3a). The particle size of HDL shifted toward smaller sizes with the increase of plasma apo C-III levels, and the shift was more remarkable when the elevation of apo C-III and apo C-II was simultaneous; and besides, higher apo A-I concentrations could modify the effect of apo C-III on HDL subclass distribution profile. Large-sized HDL(2b) particles decreased greatly for hypertriglyceridemic subjects who were characterized by elevated apo C-III and C-II accompanied with significantly lower apo A-I, which, in turn, blocked the maturation of HDL.

Effect of obesity on the plasma lipoprotein subclass profile in normoglycemic and normolipidemic men and women

OBJECTIVE

To determine the effect of obesity without the confounding effect of metabolic complications on the lipoprotein subclass profile in men and women.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 40 lean (body mass index (BMI): 18.5-25 kg/m(2)) and 40 obese (BMI: 30-45 kg/m(2)) subjects, with blood pressure <140/90 mm Hg, fasting plasma glucose concentration <100 mg per 100 ml and total triglyceride concentration <150 mg per 100 ml; all obese subjects had normal oral glucose tolerance.

MEASUREMENTS

Fasting concentrations of very low-, intermediate-, low- and high-density lipoproteins (VLDL, IDL, LDL, and HDL, respectively) and average VLDL, LDL and HDL particle sizes were evaluated by using proton nuclear magnetic resonance spectroscopy.

RESULTS

Obese compared with lean individuals of both sexes had increased plasma concentrations of VLDL (by approximately 50%), IDL (by approximately 100%), LDL (by approximately 50%), and to some extent HDL (by approximately 10%) particles (P<0.05). The contribution of large VLDL to total VLDL concentration, small LDL to total LDL concentration, and small HDL to total HDL concentration was greater in obese than lean subjects (P<0.05), resulting in larger average VLDL size but smaller average LDL and HDL sizes (P<0.05). Women, compared with men, had reduced concentrations of total VLDL particles (by approximately 10%) due to lower concentrations of large and medium VLDL and a shift toward large at the expense of small HDL particles (P<0.05), with no difference in total HDL particle concentration. IDL and total LDL concentrations and LDL subclass distribution were not different between men and women.

CONCLUSION

Obesity is associated with pro-atherogenic alterations in the lipoprotein subclass profile, which may increase cardiovascular disease risk even in the absence of classical metabolic risk factors. On the other hand, the female cardiovascular disease risk advantage is probably largely related to differences in traditional lipid risk factors (plasma triglyceride and HDL-cholesterol concentrations) because sex differences in the plasma lipoprotein subclass profile are minimal.

Dyslipidemia in obese cats

Obesity is an important endocrine disorder in cats and is a risk factor for diabetes similar to humans. The goal of this study was to examine the effect of long-term obesity and different diets (high protein, and high carbohydrate supplemented with saturated fatty acids or n-3 polyunsaturated fatty acids) on plasma lipids in the fasted and fed states in 12 lean (LEAN) and 12 obese (OBESE) cats with ultracentrifugation, and nuclear magnetic resonance spectroscopy. OBESE had higher plasma non-esterified fatty acids and triglycerides, as well as very-low-density-lipoproteins (VLDL) consisting primarily of medium-sized particles. The concentration of low-density-lipoproteins (LDL) was comparable between the groups, although OBESE had mostly very small, whereas LEAN had mostly large particles. The concentration of high-density-lipoproteins (HDL) was lower in OBESE and consisted primarily of small particles. Plasma triglycerides, and triglycerides and cholesterol in all lipoproteins increased postprandially. Different diets had little effect on lipids. Our results show that long-term obese cats develop similar lipoprotein changes to humans, yet, hypertension and atherosclerosis have not been described in obese cats. This suggests that dyslipidemia alone is not sufficient to induce hypertension and atherosclerosis. Other anti-atherogenic factors may be present in the obese, dyslipidemic cat.

Mouse models of experimental autoimmune uveitis

The mouse model of experimental autoimmune uveitis, induced by immunization of mice with the retinal protein IRBP, was developed in our laboratory 20 years ago and published in 1988. Since that time it has been adopted by many investigators and has given rise to many studies that helped elucidate genetic influences, dissect the basic mechanisms of pathogenesis and test novel immunotherapeutic paradigms. The current overview will summarize the salient features of the experimental autoimmune uveitis model and discuss its mechanisms.

Beyond HDL-cholesterol increase: phospholipid enrichment and shift from HDL3 to HDL2 in alcohol consumers

The reduction of cardiovascular mortality associated with moderate alcohol consumption is chiefly thought to be mediated by an increase of high density lipoprotein cholesterol (HDL-CH). This study highlights additional qualitative changes of HDL that might augment this antiatherogenic effect. In 279 healthy men, alcohol and nutrient consumption were evaluated. Groups 1 (n=62), 2 (n=172), and 3 (n=45) comprised subjects with alcohol consumption of 0-5.0, 5.1-30.0, and 30.1-75 g/day, respectively. Lipid analysis was performed in nonfractionated and fractionated plasma, including subfractions HDL(2a), HDL(2b), and HDL(3). No difference in LDL-cholesterol was observed. Compared with group 1, groups 2 and 3 exhibited significant increases of HDL-CH (group 1, 44 +/- 10 mg/dl; group 2, 51 +/- 11 mg/dl; group 3, 55 +/- 11 mg/dl; mean +/- SD, P<0.0005), accompanied by enhanced lipidation of HDL (increase of the HDL(2)-CH/HDL(3)-CH ratio). Moreover, phospholipid enrichment of HDL occurred in alcohol consumers, whereas the ratios between other HDL components remained constant. Multivariate analysis revealed alcohol to have the foremost statistical influence on changes of the HDL fraction, followed by body mass index and physical activity level. The increased lipidation of HDL found in alcohol consumers might augment the antiatherogenic effect of HDL-CH increase. In addition, the phospholipid enrichment of HDL might reduce the inflammatory response of atherogenesis.

Relationship Between Apolipoprotein Concentrations and HDL Subclasses Distribution

Alterations in plasma apolipoproteins levels can influence the composition, content, and distribution of plasma lipoproteins that affect the risk of atherosclerosis. This study assessed the relationship between plasma apolipoproteins levels, mainly apoAI, and HDL subclass distribution. The contents of plasma HDL subclasses were determined by two-dimensional gel electrophoresis coupled with immunodetection in 545 Chinese subjects. Compared with a low apoAI group, the contents of all HDL subclasses increased significantly both in middle and high apoAI group, and the contents of large-sized HDL(2b) increased more significantly relative to those of small-sized prebeta(1)-HDL in a high apoAI group. When apoAI and HDL-C levels increased simultaneously, in comparison to a low apoAI along with HDL-C concentration group, a significant increase (116%) was shown in HDL2b but only a slight increase (26%) in prebeta1-HDL. In addition, Pearson correlation analysis revealed that apoAI levels were positively and significantly correlated with all HDL subclasses. Multiple liner regression demonstrated that the apoAI concentrations were the most powerful predictor for HDL subclass distribution. With the elevation of apoAI concentrations, the contents of all HDL subclasses increased successively and significantly, especially, an increase in large-sized HDL(2b). Further, when apoAI and HDL-C concentrations increased simultaneously, the shift to larger HDL size was more obvious. Which, in turn, indicated that HDL maturation might be enhanced and, the reverse cholesterol transport might be strengthened along with apoAI levels which might be a more powerful factor influencing the distribution of HDL subclasses.