Interrelationships between postprandial lipoprotein B:CIII particle changes and high-density lipoprotein subpopulation profiles in mixed hyperlipoproteinemia

Preparation and activity analysis of recombinant human high-density lipoprotein

Population studies have consistently shown a highly inverse correlation between plasma concentration of high-density lipoprotein and the risk of atherosclerotic cardiovascular disease in humans. High-density lipoprotein (HDL) as a therapeutic target is an intense area of ongoing investigation. Aiming to solve the shortcomings of native HDL application, we prepared recombinant human HDL (rhHDL) that contains a similar composition and has similar functions with native HDL. Six kinds of recombinant human apolipoproteins (rhapo)-rhapoA-I, rhapoA-II, rhapoA-IV, rhapoC-I, rhapoC-II, and rhapoE-were expressed in Pichia pastoris and purified with chromatography. By the facilitation of cholate, six kinds of rhapo penetrated among the phosphatidylcholine acyl chains. After purification by density-gradient centrifugation, rhHDL was acquired. Based on morphological observation, we confirmed that the micellar complexes of rhapo with phosphatidylcholine and cholesterol were prepared. We carried on comparative studies in vitro and in vivo between native HDL and rhHDL. Cellular cholesterol efflux assays showed that rhHDL could promote the efflux of excess cholesterol from macrophages. Furthermore, rhHDL has similar effects with native HDL on the blood lipid metabolism in hyperlipidemic mice. In conclusion, rhHDL has similar effects on antiatherosclerosis with native HDL through reverse cholesterol transport, antioxidative, and antithrombotic properties. It could be used as a therapeutic HDL-replacement agent.

The relationship between high density lipoprotein subclass profile and apolipoprotein concentrations

The HDL fraction in human plasma is heterogeneous in terms of size, shape, composition, and surface charge. The HDL subclasses contents were quantified by 2-dimensional non-denaturing gel electrophoresis, immunoblotting, and image analysis. This research review systematically analyzed the relationship between the contents of HDL subclasses and the concentrations and ratios of the 5 major plasma apolipoproteins (apo). As the concentration of apoA-I increases, the contents of all HDL subclasses increase significantly. The most significant association was observed between large-sized HDL2b contents and apoA-I. ApoA-II played a dual function in the contents of HDL subclasses, and both small-sized HDL3b and HDL3a and large-sized HDL2b tended to increase with apoA-II concentration. An increase in the concentrations of apoC-II, C-III, and B-100 resulted in higher levels of small-sized HDL particles and lower levels of large-sized HDL particles. Plasma apoB- 100, apoC-II, and apoC-III appear to play a coordinated role in assembly of HDL particles and the determination of their contents. Higher concentrations of apoA-I could inhibit the reduction in content of large-sized HDL2b effected by apoB-100, C-II, and C-III. The preβ1-HDL contents increased significantly and those of HDL2b declined progressively with an increased apoB-100/apoA-I or a decreased apoC-III/apoC-II ratio. In summary, each apo has distinct but interrelated roles in HDL particle generation and metabolism. ApoA-I and apoC-II concentrations are independent determinants of HDL subtypes in circulation and apoA-I levels might be a more powerful factor to influence HDL subclasses distribution. Moreover, apoB- 100/apoA-I ratio could reliably and sensitively reflect the HDL subclass profile.

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.

Relationship between apolipoproteins and the alteration of HDL subclasses in hyperlipidemic subjects

BACKGROUND

To elucidate the relationship between the apolipoproteins, especially apoA-I and the alteration of HDL subclasses in hyperlipidemic, HTC and HTG subjects.

METHODS

ApoA-I contents of plasma HDL subclasses were quantitated by two-dimensional gel electrophoresis coupled with immunodetection in 233 normolipidemic subjects and 312 hyperlipidemic subjects (132 HTC and 180 HTG subjects). Making use of the mean +/-1 SD of apoA-I levels, we further subdivided normolipidemic, hyperlipidemic, HTC and HTG subjects into 3 subgroups, respectively.

RESULTS

Subjects in the middle and low apoA-I subgroups had decreased HDL-C and apoA-I while increased TG, apoB100, apoCII, apoCIII and apoE concentrations. With the reduction of apoA-I concentrations, the apoA-I contents of all HDL subclasses decreased successively and significantly. The relative percentage of small-sized HDL increased significantly while those of large-sized HDL(2a), HDL(2b) decreased significantly in hyperlipidemic, especially in HTG group. Multiple liner regression result revealed that apoA-I was positively and significantly correlated with all HDL subclasses and apoA-I level influenced the distribution of HDL subclasses powerfully in hyperlipidemic subjects.

CONCLUSIONS

Both the rate and efficiency of RCT might be weakened more seriously in hyperlipidemic, especially in HTG subjects with low apoA-I levels. ApoA-I level might be a powerful factor correlated with the distributions of HDL subclasses.

Alterations of high-density lipoprotein subclasses in hypercholesterolemia and combined hyperlipidemia

BACKGROUND

Alterations in plasma lipid levels can influence the composition, content, and distribution of plasma lipoprotein subclasses that effect atherosclerosis risk. Hypercholesterolemia and combined hyperlipidemia are common forms of atherogenic dyslipoproteinemia. This study evaluates the alterations of high-density lipoprotein (HDL) subclasses in hypercholesterolemic and combined hyperlipidemic subjects.

METHODS

Apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis in 242 normolipidemic subjects, 66 hypercholesterolemic subjects and 59 combined hyperlipidemic subjects.

RESULTS

Compared with the normolipidemic subjects, apolipoprotein A-I contents of small-sized pre-beta1-HDL, HDL3c, HDL3b and HDL3a were significantly higher in both hypercholesterolemic subjects (p<.01, p<.05, p<.01 and p<.05, respectively) and combined hyperlipidemic subjects (p<.01, p<.05, p<.01 and p<.01, respectively). In contrast, apolipoprotein A-I contents of large-sized HDL2a and HDL2b were significantly lower in hypercholesterolemic subjects (p<.05 and p<.01, respectively) as well as combined hyperlipidemic subjects (p<.01 and p<.01, respectively). In addition, pre-beta1-HDL increased significantly (p<.05) while HDL2a and HDL2b decreased significantly (p<.05 and p<.01, respectively) in combined hyperlipidemic group versus hypercholesterolemic subjects. With the elevation of triglyceride levels, pre-beta1-HDL, and HDL3a increased successively, however, HDL2a and HDL2b decreased successively in subjects with total cholesterol levels greater than 240 mg/dl.

CONCLUSIONS

The particle size of HDL shifted towards smaller size in hypercholesterolemic subjects, and that the shift was more prominent in combined hyperlipidemic subjects. The alternations mentioned above indicate that HDL maturation might be abnormal, and reverse cholesterol transport (RCT) might be weakened.

Alterations of high density lipoprotein subclasses in obese subjects

The object of this study was to investigate the characteristics of lipid metabolism in obese subjects, with particular emphasis on the alteration of HDL subclass contents and distributions. A population of 581 Chinese individuals was divided into four groups (25 underweight subjects, 288 of desirable weight, 187 overweight, and 45 obese) according to body mass index (BMI). Apoprotein A-I (apoA-I) contents of plasma HDL sub-classes were determined by 2-D gel electrophoresis associated with an immunodetection method. The concentrations of TG and the apoA-I content of pre-beta 1-HDL were significantly higher (P < 0.01 and P < 0.01, respectively), but the levels of HDL cholesterol, and the apoA-I contents of HDL2a and HDL2b were significantly lower (P < 0.01, P < 0.05, and P < 0.01, respectively) in obese subjects than in subjects having a desirable weight. Moreover, with the elevation of BMI, small-sized pre-beta 1-HDL increased gradually and significantly, whereas large-sized HDL2b decreased gradually and significantly. Meanwhile, the variations in HDL subclass distribution were more obvious with the elevation of TG levels in obese as well as overweight subjects. In addition, Pearson correlation analysis revealed that BMI and TG levels were positively correlated with pre-beta 1-HDL but negatively correlated with HDL2b. Multiple regression analysis also showed that TG concentrations were associated independently and positively with high pre-beta 1-HDL and independently and negatively with low HDL2b in obese and overweight subjects. The HDL particle size was smaller in obese and overweight subjects. The shift to smaller size was more obvious with the elevation of BMI and TG, especially TG levels. These observations, in turn, indicated that HDL maturation might be abnormal, and reverse cholesterol transport might be impaired.

Alterations of high-density lipoprotein subclasses in endogenous hypertriglyceridemia

BACKGROUND

To investigate the alterations of high-density lipoprotein (HDL) subclasses in endogenous hypertriglyceridemic subjects.

METHODS

Apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis in 236 normolipidemic subjects (including 146 males and 90 females) and 176 endogenous hypertriglyceridemic subjects (including 103 males and 73 females).

RESULTS

Apolipoprotein A-I contents of small-sized pre-beta1-HDL and HDL3a were significantly higher (P < .01 and P < .01, respectively), but those of large-sized HDL2a and HDL2b were significantly lower (P < .01 and P < .01, respectively) in hypertriglyceridemic subjects versus normolipidemic subjects. Moreover, with the elevation of triglyceride levels, small-sized pre-beta1-HDL and HDL3a increased successively; however, large-sized HDL2a and HDL2b decreased successively. Males had significantly higher apolipoprotein A-I contents of small-sized pre-beta1-HDL and HDL3b (P < .05 and P < .05, respectively), but lower contents of large-sized HDL2b (P < .01) than females in both normolipidemic and hypertriglyceridemic subjects.

CONCLUSIONS

The particle size of HDL shifted toward smaller size in hypertriglyceridemic subjects, especially in male subjects. Of note, the shift was more obvious with the elevation of triglyceride levels. The changes mentioned above indicate that HDL maturation might be abnormal and reverse cholesterol transport might be weakened.

Relationship between plasma lipid concentrations and HDL subclasses

BACKGROUND

It is generally accepted that different high-density lipoprotein (HDL) subclasses have distinct but interrelated metabolic functions. HDL is known to directly influence the atherogenic process and changes in HDL subclasses distribution may be related to the incidence and prevalence of atherosclerosis.

METHODS

Apo-AI contents(mg/l) of plasma HDL subclasses were determined by 2-dimensional gel electrophoresis coupled with immunodetection for apo-AI. Four hundred forty-two Chinese adults subjects aged 33 to 78 years were assigned to different groups according to the third Report of NCEP (ATP III) guidelines. The subjects were first divided into 2 groups, normal and high TG, then further classified by plasma TC, HDL-C and LDL-C concentrations. The subjects were also divided into TC desirable and TC high groups.

RESULTS

Apo-A contents of prebeta(1)-HDL were higher while HDL(2b) were lower in high TG subjects vs. the corresponding normal TG subjects according to plasma TC and LDL-C concentrations. With the increase of plasma TC concentrations, apo-AI contents of prebeta(1)-HDL were significantly higher in high TC subgroup vs. TC desirable subgroup in normal TG subjects. With the decrease of HDL-C concentrations, apo-AI contents of HDL(2b) tended to decrease in normal TG subjects. And, with the increases of LDL-C concentration, in normal TG subjects, apo-AI contents of prebeta(1)-HDL and HDL(3b) were significantly higher and those of HDL(2b) were significantly lower in very high LDL-C subgroup vs. LDL-C optimal subgroup. On the other hand, apo-AI contents of prebeta(1)-HDL and HDL(3a) were significantly higher, while HDL(2a) and HDL(2b) were significantly lower in high TG and very high TG subgroup vs. normal TG subgroup within either TC desirable or TC high subjects. In a multivariate linear regression model, TG and TC concentrations were all associated independently and positively with high prebeta(1)-HDL; however, HDL-C were inversely associated with high prebeta(1)-HDL. And TG and TC concentrations were all associated independently and negatively with low HDL(2b), but HDL-C and apo-AI were positively associated with low HDL(2b).

CONCLUSIONS

With the increase of plasma TG, TC, LDL-C or the decrease of plasma HDL-C concentrations, there was a general shift toward smaller-sized HDL, which, in turn, indicates that reverse cholesterol transport might be weakened and HDL maturation might be abnormal. Plasma TG concentration is a more important factor than TC concentration on the changes of HDL subclass distribution. Moreover, when TG is normal and HDL-C decreased, large-size HDL particles tended to decrease.

Alterations of HDL subclasses in hyperlipidemia

BACKGROUND

It is generally accepted that different high-density lipoprotein (HDL) subclasses have distinct but interrelated metabolic functions. HDL is known to directly influence the atherogenic process and changes in HDL subclasses distribution may be related to the incidence and prevalence of atherosclerosis.

METHOD

The relative apolipoprotein (apo)A-I contents (% apoA-I) of plasma HDL subclasses were determined by two-dimensional gel electrophoresis coupled with immunodetection for apoA-I, in 39 hypercholesterolemic (HTC) subjects, 97 hypertriglyceridemic (HTG) subjects and 32 mixed hyperlipidemic (MHL) subjects, and 124 normolipidemic subjects.

RESULTS

The relative apoA-I contents of prebeta(1)-HDL, prebeta(2)-HDL, HDL(3c), HDL(3b) and HDL(3a) significantly increased while HDL(2a) and HDL(2b) significantly decreased in hyperlipidemic subjects. In HTC subjects of hyperlipidemia, the concentrations of prebeta(1)-HDL were significantly lower and HDL(2b) concentrations were significantly higher than in HTG and MHL subjects. In HTG subjects, the concentrations of HDL(3a) were significantly higher and the concentrations of HDL(2b) were lower than in HTC and MHL subjects. In total hyperlipidemic subjects, plasma triglyceride (TG) concentrations showed positive correlation with prebeta(1)-HDL, prebeta(2)-HDL, HDL(3b) and HDL(3a) and negative correlation with HDL(2a) and HDL(2b). The total cholesterol (TC) concentrations showed positive correlation with the relative apoA-I contents of prebeta(1)-HDL and HDL(3b), whereas the HDL-C concentrations showed negative correlation with the relative apoA-I contents of prebeta(1)-HDL and HDL(3a) and positive correlation with those of HDL(2a) and HDL(2b). The relative apoA-I contents of prebeta(1)-HDL, prebeta(2)-HDL, HDL(3b), and HDL(3a) were positively correlated whereas those of HDL(2a) and HDL(2b) were negatively correlated with TG/HDL-C ratio.

CONCLUSION

The particle size of HDL in hyperlipidemic subjects shifted towards smaller sizes, which, in turn, indicates that the maturation of HDL may be abnormal in hyperlipidemic subjects.