LCAT-dependent conversion of prebeta1-HDL into alpha-migrating HDL is severely delayed in hemodialysis patients

HDL Function across the Lifespan: From Childhood, to Pregnancy, to Old Age

The function of high-density lipoprotein (HDL) particles has emerged as a promising therapeutic target and the measurement of HDL function is a promising diagnostic across several disease states. The vast majority of research on HDL functional biology has focused on adult participants with underlying chronic diseases, whereas limited research has investigated the role of HDL in childhood, pregnancy, and old age. Yet, it is apparent that functional HDL is essential at all life stages for maintaining health. In this review, we discuss current data regarding the role of HDL during childhood, pregnancy and in the elderly, how disturbances in HDL may lead to adverse health outcomes, and knowledge gaps in the role of HDL across these life stages.

Changes in the size and electrophoretic mobility of HDL subpopulation particles in chronic kidney disease

BACKGROUND

High-density lipoprotein (HDL) is a heterogeneous group of particles with anti-atherogenic properties whose metabolism is alterated in chronic kidney disease (CKD). The aim of this study was to evaluate the particle size and mobility of HDL subpopulations in non-dialysis CKD patients.

METHODS

The study involved 42 non-dialysis CKD patients (stages 3a-4) and 18 control subjects. HDL was separated by non-denaturing two-dimensional polyacrylamide gradient gel electrophoresis (2D-PAGGE) and eight HDL subpopulations; preβ1, preβ2a-c, and α1-4 were distinguished. The size and electrophoretic mobility of HDL subpopulation particles were compared between the groups, and a regression analysis was conducted.

RESULTS

In CKD patients, the mean sizes of α-HDL and preβ2-HDL particles were significantly lower compared to the control group (8.42 ± 0.32 nm vs. 8.64 ± 0.26 nm, p = 0.014; 11.45 ± 0.51 vs. 12.34 ± 0.78 nm, p = 0.003, respectively). The electrophoretic mobility of preβ2-HDL relative to α-HDL was significantly higher in CKD patients compared to the control group (Rf 0.65 ± 0.06 vs. 0.53 ± 0.10, p = 0.002). The size and mobility of HDL subpopulations correlated with eGFR values (p < 0.01). These relationships remained statistically significant after adjusting for age, gender, statin treatment, apolipoprotein AI, total cholesterol, and triglyceride levels.

DISCUSSION

CKD affects the size and mobility of HDL particles, which can be related to HDL dysfunction. The magnitude of HDL size and mobility changes depended on CKD stage and differed for individual HDL subpopulations, which indicates that some stages of HDL metabolism may be more affected by the presence of chronic kidney disease.

Measures of high-density lipoprotein function in men and women with severe aortic stenosis

BACKGROUND

Calcification of the aortic valve is a common heart valve disorder, in some cases leading to clinically impactful severe aortic stenosis (AS). Sex-specific differences in aortic valve calcification (ACV) exist, with women having a lower burden of calcification than men as measured by computed tomography; however, the pathophysiological mechanism that leads to these differences remains unclear.

METHODS

Using cultured human Tamm-Horsfall protein 1 (THP-1) macrophages and human aortic valve interstitial cells, the effects of high-density lipoprotein (HDL) particles isolated from the plasma of men and women with severe AS were studied for cholesterol efflux capacity (CEC).

RESULTS

HDL-CEC was assessed in 46 patients with severe AS, n = 30 men, n = 16 women. ATP-Binding Cassette A1 (ABCA1)-mediated HDL-CEC was measured from human cultured THP-1 macrophages to plasma HDL samples. Women with severe AS had more ABCA1-mediated HDL-CEC, as compared to men (8.50 ± 3.90% cpm vs. 6.80 ± 1.50% cpm, P = 0.04). HDL pre-β1 and α-particles were higher in woman than in men by spectral density, (pre-β1 HDL, 20298.29 ± 1076.15 vs. 15,661.74 ± 789.00, P = 0.002, and α-HDL, 63006.35 ± 756.81 vs. 50,447.00 ± 546.52, P = 0.03). Lecithin-cholesterol acyltransferase conversion of free cholesterol into cholesteryl esters was higher in women than men (16.44 ± 9.11%/h vs. 12.00 ± 8.07%/h, P = 0.03).

CONCLUSIONS

Sex-specific changes in various parameters of HDL-CEC were found in patients with severe AS. Sex-based modifications in HDL functionality by HDL-CEC might account for the reduced burden of calcification in women vs. men with severe AS. Therefore, future studies should target sex-related pathways in AS to help to improve understanding and treatment of AS. Sex specifc differences in AVC and differences associated with HDL function in men and women with severe AS. When compared to men, women had higher preβ-HDL and α-HDL migrating particles, higher cholesterol efflux to HDL, and higher lecithin cholesterol acyl transferase (LCAT) activity, possibly indicating that improved reverse cholesterol transport may be protective against worsened calcification.

Cholesterol efflux promoting function of high-density lipoproteins in calcific aortic valve stenosis

Background and aims

Cholesterol efflux capacity is a functional property of high-density lipoproteins (HDL) reflecting the efficiency of the atheroprotective reverse cholesterol transport process in humans. Its relationship with calcific aortic valve stenosis (CAVS) has not been fully assessed yet.

Methods

We evaluated HDL-CEC in a patient population with varying degrees of aortic valvular calcific disease, assessed using echocardiography and cardiac computed tomography. Measurement of biomarkers that reflect osteogenic and tissue remodeling, along with dietary and gut microbiota-derived metabolites were performed.

Results

Patients with moderate-severe CAVS had significantly lower HDL-CEC compared to both control and aortic sclerosis subjects (mean: 6.09%, 7.32% and 7.26%, respectively). HDL-CEC displayed negative correlations with peak aortic jet velocity and aortic valve calcium score, indexes of CAVS severity (ρ = -0.298, p = 0.002 and ρ = -0.358, p = 0.005, respectively). In multivariable regression model, HDL-CEC had independent association with aortic valve calcium score (B: -0.053, SE: 0.014, p < 0.001), GFR (B: -0.034, SE: 0.012, p = 0.007), as well as with levels of total cholesterol (B: 0.018, SE: 0.005, p = 0.002).

Conclusion

These results indicate an impairment of HDL-CEC in moderate-severe CAVS and may contribute to identify potential novel targets for CAVS management.

High-Density Lipoproteins and the Kidney

Dyslipidemia is a typical trait of patients with chronic kidney disease (CKD) and it is typically characterized by reduced high-density lipoprotein (HDL)-cholesterol(c) levels. The low HDL-c concentration is the only lipid alteration associated with the progression of renal disease in mild-to-moderate CKD patients. Plasma HDL levels are not only reduced but also characterized by alterations in composition and structure, which are responsible for the loss of atheroprotective functions, like the ability to promote cholesterol efflux from peripheral cells and antioxidant and anti-inflammatory proprieties. The interconnection between HDL and renal function is confirmed by the fact that genetic HDL defects can lead to kidney disease; in fact, mutations in apoA-I, apoE, apoL, and lecithin–cholesterol acyltransferase (LCAT) are associated with the development of renal damage. Genetic LCAT deficiency is the most emblematic case and represents a unique tool to evaluate the impact of alterations in the HDL system on the progression of renal disease. Lipid abnormalities detected in LCAT-deficient carriers mirror the ones observed in CKD patients, which indeed present an acquired LCAT deficiency. In this context, circulating LCAT levels predict CKD progression in individuals at early stages of renal dysfunction and in the general population. This review summarizes the main alterations of HDL in CKD, focusing on the latest update of acquired and genetic LCAT defects associated with the progression of renal disease.

Current Understanding of the Relationship of HDL Composition, Structure and Function to Their Cardioprotective Properties in Chronic Kidney Disease

In the general population, the ability of high-density lipoproteins (HDLs) to promote cholesterol efflux is a predictor of cardiovascular events, independently of HDL cholesterol levels. Although patients with chronic kidney disease (CKD) have a high burden of cardiovascular morbidity and mortality, neither serum levels of HDL cholesterol, nor cholesterol efflux capacity associate with cardiovascular events. Important for the following discussion on the role of HDL in CKD is the notion that traditional atherosclerotic cardiovascular risk factors only partially account for this increased incidence of cardiovascular disease in CKD. As a potential explanation, across the spectrum of cardiovascular disease, the relative contribution of atherosclerotic cardiovascular disease becomes less important with advanced CKD. Impaired renal function directly affects the metabolism, composition and functionality of HDL particles. HDLs themselves are a heterogeneous population of particles with distinct sizes and protein composition, all of them affecting the functionality of HDL. Therefore, a more specific approach investigating the functional and compositional features of HDL subclasses might be a valuable strategy to decipher the potential link between HDL, cardiovascular disease and CKD. This review summarizes the current understanding of the relationship of HDL composition, metabolism and function to their cardio-protective properties in CKD, with a focus on CKD-induced changes in the HDL proteome and reverse cholesterol transport capacity. We also will highlight the gaps in the current knowledge regarding important aspects of HDL biology.

Low-Density Lipoprotein Cholesterol/High-Density Lipoprotein Cholesterol Ratio and Carotid Intima-Media Thickness: A Cohort Study in China

Low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (LDL-C/HDL-C) ratio may carry additional information and has been suggested as a better predictor for atherosclerosis progression and cardiovascular disease (CVD) than LDL-C and HDL-C alone. Therefore, we aim to explore the association between LDL-C/HDL-C ratio and high carotid intima-media thickness (CIMT) risk in a large Cohort in Beijing, China. This cohort study included 13,612 adults without high CIMT at first entry and who attended the baseline examination and at least one follow-up annual examination between 2009 and 2016. We used multivariable Cox regression to estimate hazard ratios (HR) with their 95% confidence intervals (CI) for the association between LDL-C/HDL-C ratio and risk of high CIMT. During 37,912 person-years of follow-up, 1996 (1268 men and 728 women) developed high CIMT. Compared with the first quartile of LDL-C/HDL-C ratio, the risk of high CIMT was significantly increased for the fourth quartile of LDL-C/HDL-C ratio (HR = 1.51, 95% CI: 1.29-1.78). We observed a significant association between LDL-C/HDL-C ratio and high CIMT risk comparing LDL-C/HDL-C ratio >2.78 with LDL-C/HDL-C ratio ≤2.78 and significant dose-response relationship between LDL-C/HDL-C ratio and risk of high CIMT. The restricted cubic spline showed a significant nonlinear association between LDL-C/HDL-C ratio and the risk of high CIMT (p_{non-linearity} = 0.009). We identify a significant association between LDL-C/HDL-C ratio and the risk of high CIMT in the Chinese Cohort study. Future studies are needed to evaluate the effectiveness of reducing LDL-C/HDL-C ratio treatment on the development of high CIMT.

Preβ1-high-density lipoprotein metabolism is delayed in patients with chronic kidney disease not on hemodialysis

BACKGROUND

Preβ1-high-density lipoprotein (HDL) is a lipid-poor cholesterol acceptor that is converted to lipid-rich HDL by lecithin-cholesterol acyltransferase (LCAT). In patients receiving hemodialysis, preβ1-HDL metabolism is hampered even if HDL cholesterol is normal. Hemodialysis may affect preβ1-HDL metabolism by releasing lipases from the vascular wall due to heparin.

OBJECTIVES

We investigated whether preβ1-HDL metabolism is delayed in patients with chronic kidney disease (CKD) who are not receiving hemodialysis.

METHODS

We examined 44 patients with Stage 3 or higher CKD and 22 healthy volunteers (Control group). The patients with CKD were divided into those without renal replacement therapy (CKD group, n = 22) and those undergoing continuous ambulatory peritoneal dialysis (CAPD group, n = 22). Plasma preβ1-HDL concentrations were determined by immunoassay. During incubation at 37°C, we used 5,5-dithio-bis (2-nitrobenzoic acid) (DTNB) to inhibit LCAT activity and defined the conversion halftime of preβ1-HDL (CHT_preβ1) as the time required for the difference in preβ1-HDL concentration in the presence and absence of 5,5-DTNB to reach half the baseline concentration.

RESULTS

The absolute and relative preβ1-HDL concentrations were higher, and CHT_preβ1 was longer in the CKD and CAPD groups than in the Control group. Preβ1-HDL concentration was significantly correlated with CHT_preβ1 but not with LCAT activity in patients with CKD and CAPD.

CONCLUSION

Preβ1-HDL metabolism is delayed in patients with CKD who are not on hemodialysis. This preβ1-HDL metabolic delay may progress as renal function declines.

LDL-cholesterol to HDL-cholesterol ratio discordance with lipid parameters and carotid intima-media thickness: a cohort study in China

Background

The discordance of the low-density lipoprotein cholesterol-to-high-density lipoprotein cholesterol (LDL-C/HDL-C) ratio with alterative lipid parameters may explain the inconsistent association of CIMT with the LDL-C/HDL-C ratio. Therefore, this study aimed to explore the associations between LDL-C/HDL-C ratio discordance with alternative lipid parameters and elevated carotid intima-media thickness (CIMT) risk in a large cohort in Beijing, China.

Methods

In total, 13,612 adults who didn’t have elevated CIMT at baseline and who participated in at least one follow-up of annual examination between 2009 and 2016 were included in this cohort study. A multivariable Cox regression model was utilized to evaluate the associations of discordance of the LDL-C/HDL-C ratio with TC, TGs, LDL-C and HDL-C with elevated CIMT risk.

Results

During 37,999 person-years of follow-up, 2004 individuals (1274 men and 730 women) developed elevated CIMT. Among individuals with normal TC and TGs, 16.6 and 15.2% individuals had a discordantly high LDL-C/HDL-C ratio, respectively, and the risk of elevated CIMT increased by 1.54 (95% CI 1.33, 1.77) and 1.53 (95% CI 1.33, 1.76), respectively, comparing to individuals with a concordantly low LDL-C/HDL-C ratio. A high LDL-C/HDL-C ratio could significantly increase elevated CIMT risk regardless of discordance/concordance with LDL-C and HDL-C (P < 0.001). A low LDL-C/HDL-C ratio with discordantly normal HDL-C and high LDL-C (13.2% of individuals) had a 32% (HR = 1.32, 95% CI 1.11, 1.57) higher risk of elevated CIMT than concordantly low LDL-C and normal HDL-C. Sensitivity analysis by excluding CIMT developed in the first 2 years follow-up further confirmed the above results.

Conclusions

A high LDL-C/HDL-C ratio could significantly increase elevated CIMT risk regardless of discordance/concordance with TC, TGs, LDL-C and HDL-C Even a low LDL-C/HDL-C ratio with discordantly high LDL-C and normal HDL-C could also significantly increase CIMT risk. Individuals should maintain both the LDL-C/HDL-C ratio and LDL-C at normal levels to prevent elevated CIMT.

Paraoxonase 1 and atherosclerosis-related diseases

A direct and an indirect relationship between paraoxonase 1 (PON1) and atherosclerosis exists. Given PON1's physical location within high-density lipoprotein (HDL) particles and its recognized enzyme activity, it is certainly reasonable to suggest that PON1 facilitates the antiatherogenic nature of HDL particles. PON1 also plays a role in regulating reverse cholesterol transport, antioxidative, anti-inflammatory, antiapoptotic, vasodilative, and antithrombotic activities and several endothelial cell functions. HDL dysfunctionality is a more recent issue and seems to be centered on pathological conditions affecting HDL structure and size profiles. This review is focused on the role of PON1 status in different atherosclerosis-related diseases that we have studied over the last twenty years (coronary heart disease, acute ischemic stroke, diabetes mellitus type 2, end-stage renal disease, chronic obstructive pulmonary disease, and sarcoidosis) with the aim to determine the true value of PON1 as a biomarker. The role of PON1 in cancer is also covered, as risk factors and mechanisms underlying both atherosclerosis and cancer share common features.

Lipid-modifying therapy in chronic kidney disease: Pathophysiological and clinical considerations

Chronic kidney disease (CKD), which affects >10% of the population worldwide, is associated with a dramatically increased rate of cardiovascular disease (CVD). More people with CKD will die from CVD than develop end-stage renal disease with dialysis-dependency. However, the contribution of classical atherosclerotic cardiovascular risk factors is less evident than in the general population. Particularly, the relationship between dyslipidemia and CVD morbidity and mortality in CKD patients is not as evident as in the general population. While LDL cholesterol-lowering drugs such as statins significantly reduce the rate of cardiovascular events in the general population, their role in patients with end-stage renal disease has been questioned. This could be caused by a shift from atherosclerotic to non-atherosclerotic CVD in patients with advanced CKD, which cannot be effectively prevented by lipid-lowering drugs. In addition, many lines of evidence suggest that impaired renal function directly affects the metabolism, composition and functionality of lipoproteins, which may affect their responsiveness to pharmacological interventions. In this review, we highlight the challenges for the therapeutic application of lipid-lowering treatment strategies in CKD and discuss why treatment strategies used in the general population cannot be applied uncritically to CKD patients.

Plasma Levels of Preβ1-HDL Are Significantly Elevated in Non-Dialyzed Patients with Advanced Stages of Chronic Kidney Disease

In chronic kidney disease (CKD), the level of high-density lipoprotein (HDL) decreases markedly, but there is no strong inverse relationship between HDL-cholesterol (HDL-C) and cardiovascular diseases. This indicates that not only the HDL-C level, but also the other quantitative changes in the HDL particles can influence the protective functionality of these particles, and can play a key role in the increase of cardiovascular risk in CKD patients. The aim of the present study was the evaluation of the parameters that may give additional information about the HDL particles in the course of progressing CKD. For this purpose, we analyzed the concentrations of HDL containing apolipoprotein A-I without apolipoprotein A-II (LpA-I), preβ1-HDL, and myeloperoxidase (MPO), and the activity of paraoxonase-1 (PON-1) in 68 patients at various stages of CKD. The concentration of HDL cholesterol, MPO, PON-1, and lecithin-cholesterol acyltransferase (LCAT) activity were similar in all of the analyzed stages of CKD. We did not notice significant changes in the LpA-I concentrations in the following stages of CKD (3a CKD stage: 57 ± 19; 3b CKD stage: 54 ± 15; 4 CKD stage: 52 ± 14; p = 0.49). We found, however, that the preβ1-HDL concentration and preβ1-HDL/LpA-I ratio increased along with the progress of CKD, and were inversely correlated with the estimated glomerular filtration rate (eGFR), even after adjusting for age, gender, triacylglycerols (TAG), HDL cholesterol, and statin therapy (β = −0.41, p < 0.001; β = −0.33, p = 0.001, respectively). Our results support the earlier hypothesis that kidney disease leads to the modification of HDL particles, and show that the preβ1-HDL concentration is significantly elevated in non-dialyzed patients with advanced stages of CKD.

Moderate Renal Impairment Does Not Impact the Ability of CSL112 (Apolipoprotein A-I [Human]) to Enhance Cholesterol Efflux Capacity

CSL112 (apolipoprotein A‐I [human]) is a novel intravenous formulation of plasma‐derived apolipoprotein A‐I (apoA‐I) that enhances cholesterol efflux capacity. Renal impairment is a common comorbidity in acute myocardial infarction patients and is associated with impaired lipid metabolism. The aim of this phase 1 study was to assess the impact of moderate renal impairment on the pharmacokinetic and pharmacodynamic profile of CSL112. Sixteen subjects with moderate renal impairment and 16 age‐, sex‐, and weight‐matched subjects with normal renal function participated in the study. Within each renal function cohort, subjects were randomized 3:1 to receive a single intravenous infusion of CSL112 2 g (n = 6) or placebo (n = 2) or CSL112 6 g (n = 6) or placebo (n = 2). At baseline, subjects with moderate renal impairment versus normal renal function had higher total cholesterol efflux, ABCA1‐dependent cholesterol efflux capacity, and pre‐β1‐high‐density lipoprotein (HDL) levels. Infusing CSL112 resulted in similar, immediate, robust, dose‐dependent elevations in apoA‐I and cholesterol efflux capacity in both renal function cohorts and significantly greater elevations in pre‐β1‐HDL (P < .05) in moderate renal impairment. Lecithin‐cholesterol acyltransferase activity, demonstrated by a time‐dependent change in the ratio of unesterified to esterified cholesterol, did not differ by renal function. No meaningful changes in proatherogenic lipid levels were observed. Moderate renal impairment did not impact the ability of CSL112 to enhance cholesterol efflux capacity. CSL112 may represent a novel therapy to reduce the risk of early recurrent cardiovascular events following acute myocardial infarction in patients with or without moderate renal impairment.

HDL functionality and cardiovascular outcome among nondialysis chronic kidney disease patients

CVD remains the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD profoundly affects HDL composition and functionality, but whether abnormal HDL independently contributes to cardiovascular events in CKD patients remains elusive. In the present study, we assessed whether compositional and functional properties of HDL predict cardiovascular outcome among 526 nondialysis CKD patients who participate in the CARE FOR HOMe study. We measured HDL cholesterol, the content of HDL-associated proinflammatory serum amyloid A (SAA), and activities of the HDL enzymes paraoxonase and lipoprotein-associated phospholipase A2 (Lp-PLA₂). In addition, we assessed the antioxidative activity of apoB-depleted serum. During a mean follow-up of 5.1 ± 2.1 years, 153 patients reached the predefined primary endpoint, a composite of atherosclerotic cardiovascular events including cardiovascular mortality and death of any cause. In univariate Cox regression analyses, lower HDL-cholesterol levels, higher HDL-associated SAA content, and lower paraoxonase activity predicted cardiovascular outcome, while Lp-PLA₂ activity and antioxidative capacity did not. HDL-cholesterol and HDL-paraoxonase activity lost their association with cardiovascular outcome after adjustment for traditional cardiovascular and renal risk factors, while SAA lost its association after further adjustment for C-reactive protein. In conclusion, our data suggest that neither HDL quantity nor HDL composition or function independently predict cardiovascular outcome among nondialysis CKD patients.

Managing Diabetes and Cardiovascular Risk in Chronic Kidney Disease Patients

We discuss mechanisms of increased cardiovascular disease (CVD) in patients with chronic kidney disease (CKD) and strategies for managing cardiovascular (CV) risk in these patients. Our focus was mainly on decreasing CV events and progression of microvascular complications by reducing levels of glucose and lipids. We searched PubMed with no limit on the date of the article. All articles were discussed among all authors. We chose pertinent articles, and searched their references in turn for additional relevant publications.

Lipid-Lowering Therapy in CKD: Should We Use It and in Which Patients

BACKGROUND

Chronic kidney disease is associated with a 15-fold increase in the risk of death and a 30-fold increase in the risk of cardiovascular events even prior to dialysis initiation, and this situation remains unchanged following the initiation of the dialysis procedure. Lipoprotein structure and function, especially the anti-oxidative properties of high-density lipoprotein, are altered. In this study, the effectiveness of lipid-lowering therapy on mortality and cardiovascular outcomes is explored.

SUMMARY

Mortality is inversely associated with the cholesterol level. The degree of inflammation and wasting is a stronger predictor of mortality than are cholesterol levels. Treatment with statins reduces the risk of death and cardiovascular outcomes among patients not yet requiring renal replacement therapy, but is not effective once dialysis is initiated, most likely because other processes, such as inflammation, not affected by lipid-lowering therapy, dominate in the causal pathway leading to adverse outcomes. Fenofibrate is also useful in reducing cardiovascular outcomes and the progression of renal disease among patients with type 2 diabetes not yet requiring dialysis. While the lipid-lowering therapy is effective in patients with the nephrotic syndrome, no long-term outcome studies regarding hard outcomes are available.

KEY POINTS

The great increase in cardiovascular outcomes in patients with kidney disease is likely due to a consequence of properties that are unresponsive to the lipid-lowering therapy, most likely inflammation. The lipid-lowering therapy is useful in patients who are not yet in need of dialysis but does not reduce mortality in dialysis patients.

Elevated levels of preβ1-high-density lipoprotein are associated with cholesterol ester transfer protein, the presence and severity of coronary artery disease

Background

Preβ1-high-density lipoprotein (preβ1-HDL), plays an important role in reverse cholesterol transport and exhibits potent risk for coronary artery disease (CAD). However, the association of plasma preβ1-HDL and cholesterol ester transfer protein (CETP) levels in CAD patients and the relationship of preβ1-HDL with extent of CAD are debatable.

Methods

Preβ1-HDL and CETP levels were measured by enzymed-linked immunosorbent assay (ELISAs) in 88 acute coronary syndromes (ACS), 79 stable coronary artery disease (SCAD) patients and 85 control subjects. The correlation analyses, multiple linear regression analyses and logistic regression analyses were performed, respectively.

Results

The preβ1-HDL and CETP levels in ACS patients were significantly higher than those in SCAD patients and both of them were higher than controls’. Preβ1-HDL levels were positively associated with CETP (R = 0.348, P = 0.000), the diameter of stenosis (R = 0.253, P = 0.005), the number of vessel disease (R = 0.274, P = 0.002) and Gensini score (R = 0.227, P = 0.009) in CAD patients. Stepwise multiple linear regression analyses showed that CETP was one of the determinants of preβ1-HDL levels. Logistic regression analysis revealed that elevated preβ1-HDL and CETP were potential risk factors for both ACS and SCAD.

Conclusion

The elevated preβ1-HDL levels may change with CETP concentrations in CAD patients and were related to the presence and severity of CAD.

Treatment of Hyperlipidemia Changes With Level of Kidney Function-Rationale

Lipoprotein abnormalities such as low levels of high-density lipoprotein (HDL) and high triglycerides (TGs), associated with the metabolic syndrome, are also associated with subsequent decline in kidney function. Patients with end-stage kidney disease also exhibit low HDL and high TGs and a modest reduction in low-density lipoprotein (LDL), although the mechanisms responsible for these changes differ when patients with end-stage kidney disease are compared with those having metabolic syndrome with normal kidney function, as do lipoprotein structures. Among dialysis patients, oxidized LDL, levels of TG-rich intermediate-density lipoprotein, and low HDL are associated with aortic pulsewave velocity and other markers of atherosclerosis. Statins are effective in reducing LDL and do decrease risk of cardiovascular events in patients with CKD not requiring dialysis but have no significant effect on outcomes, including all-cause mortality among dialysis patients. Similarly gemfibrozil and other fibrates lower TGs, increase HDL, and reduce cardiovascular events, but not mortality, among patients with CKD not requiring dialysis but have no significant effect on cardiovascular outcomes in dialysis patients. There is potential clinical benefit in treating elevated LDL, TGs, and low HDL in patients with CKD using statins or fibrates in those not yet requiring dialysis.

Etiology and management of dyslipidemia in children with chronic kidney disease and end-stage renal disease

Lipids are essential components of cell membranes, contributing to cell fuel, myelin formation, subcellular organelle function, and steroid hormone synthesis. Children with chronic kidney disease (CKD) and end-stage renal disease (ESRD) exhibit various co-morbidities, including dyslipidemia. The prevalence of dyslipidemias in children with CKD and ESRD is high, being present in 39-65% of patients. Elevated lipid levels in children without renal disease are a risk factor for cardiovascular disease (CVD), while the risk for CVD in pediatric CKD/ESRD is unclear. The pathogenesis of dyslipidemia in CKD features various factors, including increased levels of triglycerides, triglyceride-rich lipoproteins, apolipoprotein C3 (ApoC-III), decreased levels of cholesterylester transfer protein and high-density lipoproteins, and aberrations in serum very low-density and intermediate-density lipoproteins. If initial risk assessment indicates that a child with advanced CKD has 2 or more co-morbidities for CVD, first-line treatment should consist of non-pharmacologic management such as therapeutic lifestyle changes and dietary counseling. Pharmacologic treatment of dyslipidemia may reduce the incidence of CVD in children with CKD/ESRD, but randomized trials are lacking. Statins are the only class of lipid-lowering drugs currently approved by the U.S. Food and Drug Administration (FDA) for use in the pediatric population. FDA-approved pediatric labeling for these drugs is based on results from placebo-controlled trial results, showing 30-50% reductions in baseline low-density lipoprotein cholesterol. Although statins are generally well tolerated in adults, a spectrum of adverse events has been reported with their use in both the clinical trial and post-marketing settings.

HDL abnormalities in nephrotic syndrome and chronic kidney disease

Normal HDL activity confers cardiovascular and overall protection by mediating reverse cholesterol transport and through its potent anti-inflammatory, antioxidant, and antithrombotic functions. Serum lipid profile, as well as various aspects of HDL metabolism, structure, and function can be profoundly altered in patients with nephrotic range proteinuria or chronic kidney disease (CKD). These abnormalities can, in turn, contribute to the progression of cardiovascular complications and various other comorbidities, such as foam cell formation, atherosclerosis, and/or glomerulosclerosis, in affected patients. The presence and severity of proteinuria and renal insufficiency, as well as dietary and drug regimens, pre-existing genetic disorders of lipid metabolism, and renal replacement therapies (including haemodialysis, peritoneal dialysis, and renal transplantation) determine the natural history of lipid disorders in patients with kidney disease. Despite the adverse effects associated with dysregulated reverse cholesterol transport and advances in our understanding of the underlying mechanisms, safe and effective therapeutic interventions are currently lacking. This Review provides an overview of HDL metabolism under normal conditions, and discusses the features, mechanisms, and consequences of HDL abnormalities in patients with nephrotic syndrome or advanced CKD.

Residual Cardiovascular Risk in Chronic Kidney Disease: Role of High-density Lipoprotein

Although reducing low-density lipoprotein-cholesterol (LDL-C) levels with lipid-lowering agents (statins) decreases cardiovascular disease (CVD) risk, a substantial residual risk (up to 70% of baseline) remains after treatment in most patient populations. High-density lipoprotein (HDL) is a potential contributor to residual risk, and low HDL-cholesterol (HDL-C) is an established risk factor for CVD. However, in contrast to conventional lipid-lowering therapies, recent studies show that pharmacologic increases in HDL-C levels do not bring about clinical benefits. These observations have given rise to the concept of dysfunctional HDL where increases in serum HDL-C may not be beneficial because HDL loss of function is not corrected by or even intensified by the therapy. Chronic kidney disease (CKD) increases CVD risk, and patients whose CKD progresses to end-stage renal disease (ESRD) requiring dialysis are at the highest CVD risk of any patient type studied. The ESRD population is also unique in its lack of significant benefit from standard lipid-lowering interventions. Recent studies indicate that HDL-C levels do not predict CVD in the CKD population. Moreover, CKD profoundly alters metabolism and composition of HDL particles and impairs their protective effects on functions such as cellular cholesterol efflux, endothelial protection, and control of inflammation and oxidation. Thus, CKD-induced perturbations in HDL may contribute to the excess CVD in CKD patients. Understanding the mechanisms of vascular protection in renal disease can present new therapeutic targets for intervention in this population.

Acquired lecithin:cholesterol acyltransferase deficiency as a major factor in lowering plasma HDL levels in chronic kidney disease

OBJECTIVES

It has been suggested that a low plasma high-density lipoprotein cholesterol (HDL-C) level contributes to the high cardiovascular disease risk of patients with chronic kidney disease (CKD), especially those undergoing haemodialysis (HD). The present study was conducted to gain further understanding of the mechanism(s) responsible for the low HDL-C levels in patients with CKD and to separate the impact of HD from that of the underlying CKD.

METHODS

Plasma lipids and lipoproteins, HDL subclasses and various cholesterol esterification parameters were measured in a total of 248 patients with CKD, 198 of whom were undergoing HD treatment and 40 healthy subjects.

RESULTS

Chronic kidney disease was found to be associated with highly significant reductions in plasma HDL-C, unesterified cholesterol, apolipoprotein (apo)A-I, apoA-II and LpA-I:A-II levels in both CKD cohorts (with and without HD treatment). The cholesterol esterification process was markedly impaired, as indicated by reductions in plasma lecithin:cholesterol acyltransferase (LCAT) concentration and activity and cholesterol esterification rate, and by an increase in the plasma preβ-HDL content. HD treatment was associated with a further lowering of HDL levels and impaired plasma cholesterol esterification. The plasma HDL-C level was highly significantly correlated with LCAT concentration (R = 0.438, P < 0.001), LCAT activity (R = 0.243, P < 0.001) and cholesterol esterification rate (R = 0.149, P = 0.031). Highly significant correlations were also found between plasma LCAT concentration and levels of apoA-I (R = 0.432, P < 0.001), apoA-II (R = 0.275, P < 0.001), LpA-I (R = 0.326, P < 0.001) and LpA-I:A-II (R = 0.346, P < 0.001).

CONCLUSION

Acquired LCAT deficiency is a major cause of low plasma HDL levels in patients with CKD, thus LCAT is an attractive target for therapeutic intervention to reverse dyslipidaemia, and possibly lower the cardiovascular disease risk in these patients.

Dialysis Modalities and HDL Composition and Function

Lipid abnormalities may have an effect on clinical outcomes of patients on dialysis. Recent studies have indicated that HDL dysfunction is a hallmark of ESRD. In this study, we compared HDL composition and metrics of HDL functionality in patients undergoing hemodialysis (HD) or peritoneal dialysis (PD) with those in healthy controls. We detected a marked suppression of several metrics of HDL functionality in patients on HD or PD. Compositional analysis revealed that HDL from both dialysis groups shifted toward a more proinflammatory phenotype with profound alterations in the lipid moiety and protein composition. With regard to function, cholesterol efflux and anti-inflammatory and antiapoptotic functions seemed to be more severely suppressed in patients on HD, whereas HDL-associated paraoxonase activity was lowest in patients on PD. Quantification of enzyme activities involved in HDL metabolism suggested that HDL particle maturation and remodeling are altered in patients on HD or PD. In summary, our study provides mechanistic insights into the formation of dysfunctional HDL in patients with ESRD who are on HD or PD.

High-density lipoprotein: structural and functional changes under uremic conditions and the therapeutic consequences

High-density lipoprotein (HDL) has attracted interest as a therapeutic target in cardiovascular diseases in recent years. Although many functional mechanisms of the vascular protective effects of HDL have been identified, increasing the HDL plasma level has not been successful in all patient cohorts with increased cardiovascular risk. The composition of the HDL particle is very complex and includes diverse lipids and proteins that can be modified in disease conditions. In patients with chronic kidney disease (CKD), the accumulation of uremic toxins, high oxidative stress, and chronic micro-inflammatory conditions contribute to changes in the HDL composition and may also account for protein/lipid modifications. These conditions are associated with a decreased protective function of HDL. Therefore, the HDL quantity and the functional quality of the particle must be considered. This review summarizes the current knowledge of dyslipidemia in CKD patients, the effects of lipid-modulating therapy, and the structural modifications of HDL that are associated with dysfunction.

Changes in serum inflammatory markers are associated with changes in apolipoprotein A1 but not B after the initiation of dialysis

BACKGROUND

Few studies have examined the changes in lipoproteins over time and how inflammation is associated with lipoprotein concentrations among patients with end-stage renal disease on dialysis. One possible explanation for the association of low LDL cholesterol concentration and adverse outcomes is that inflammation reduces selected apolipoprotein concentrations.

METHODS

Serum samples were collected from a subsample of patients enrolled into the Comprehensive Dialysis Study every 3 months for up to 1 year. We examined the relation between temporal patterns in levels of inflammatory markers and changes in apolipoproteins (apo) A1 and B and the apo B/A1 ratio using linear mixed effects modeling and adjusting for potential confounders.

RESULTS

We enrolled 266 participants from 56 dialysis facilities. The mean age was 62 years, 45% were women and 26% were black. Apo A1 was lower among patients with higher Quetelet's (body mass) index (BMI), diabetes mellitus and atherosclerosis. Apo B was lower among older patients, patients with higher serum creatinine and patients with lower BMI. Over the course of a year, apo A1 changed inversely with serum concentrations of the acute phase proteins C-reactive protein (CRP) and α1 acid glycoprotein (α1AG), while apo B did not. Changes in α1AG were more strongly associated with changes in apolipoprotein concentrations than were changes in CRP; increases in α1AG were associated with decreases in apo A1 and increases in the apo B/A1 ratio.

CONCLUSIONS

Changes in inflammatory markers were associated with changes in apo A1, but not apo B over 1 year, suggesting that reductions in high-density lipoprotein cholesterol are associated with inflammation, either of which could mediate cardiovascular risk, but not supporting a hypothesis linking increased risk of low levels of apo B containing lipoproteins to the risk associated with inflammation.

Increase of electronegative-LDL-fraction ratio and IDL-cholesterol in chronic kidney disease patients with hemodialysis treatment

Background

It is known that the increased level of IDL and oxidized LDL are associated with risk of cardiovascular disease, and the lipoprotein abnormalities accelerate atherosclerosis. Cardiovascular disease is a major cause of mortality in chronic kidney disease patients with hemodialysis treatment (HD-Ps). Therefore, the estimation of lipoprotein profiles is important for prevention of cardiovascular disease in HD-Ps. We previously established an anion-exchange chromatographic method for measurement of cholesterol level in subclasses of HDL and LDL, IDL, VLDL, and chylomicron. An electronegative-LDL-fraction contained minimally oxidized-LDL. Lipoprotein profile can be accurately and conveniently determined by the new method.

Finding

In this study, lipoprotein profiles in HD-Ps and age-matched healthy subjects were estimated by using our established anion-exchange chromatographic method. The ratio of electronegative-LDL-cholesterol to total LDL-cholesterol and IDL-cholesterol in HD-Ps were significant higher than those in healthy subjects.

Conclusions

The results suggest that the ratio of electronegative-LDL-cholesterol to total LDL-cholesterol and IDL-cholesterol obtained by the new method may serve as useful markers for risk of cardiovascular disease in HD-Ps.

Imaging apolipoprotein AI in vivo

Coronary disease risk increases inversely with high-density lipoprotein (HDL) level. The measurement of the biodistribution and clearance of HDL in vivo, however, has posed a technical challenge. This study presents an approach to the development of a lipoprotein MRI agent by linking gadolinium methanethiosulfonate (Gd[MTS-ADO3A]) to a selective cysteine mutation in position 55 of apo AI, the major protein of HDL. The contrast agent targets both liver and kidney, the sites of HDL catabolism, whereas the standard MRI contrast agent, gadolinium-diethylenetriaminepentaacetic acid-bismethylamide (GdDTPA-BMA, gadodiamide), enhances only the kidney image. Using a modified apolipoprotein AI to create an HDL contrast agent provides a new approach to investigate HDL biodistribution, metabolism and regulation in vivo.

Disturbed apolipoprotein A-I-containing lipoproteins in fish-eye disease are improved by the lecithin:cholesterol acyltransferase produced by gene-transduced adipocytes in vitro

We report the in vitro efficacy of recombinant LCAT produced by lcat gene-transduced proliferative adipocytes (ccdPA/lcat), which has been developed for enzyme replacement therapy. ApoA-I-specific immunodetection in combination with 1D and 2D gel electrophoreses showed that the disturbed high-density lipoprotein subpopulation profile was clearly ameliorated by the in vitro incubation with ccdPA/lcat-derived recombinant LCAT. Thus, these results using ccdPA/lcat strongly suggest the cell implantation could contribute the enzyme replacement for the patients with LCAT deficiency.

Profiles of inflammatory markers and lipoprotein subclasses in patients undergoing continuous ambulatory peritoneal dialysis

BACKGROUND

Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) often have inflammation and dyslipidemia that accelerate to atherosclerosis. This study aimed to evaluate chronic inflammation and dyslipidemia in CAPD patients.

METHODS

We measured inflammatory markers and lipoprotein subclasses in 20 CAPD patients (12 men and 8 women, aged 59.5 ± 9.9 y) and 20 gender-matched controls. Lipoproteins were separated by high-performance liquid chromatography (HPLC) using an anion-exchange column.

RESULTS

High-sensitivity C-reactive protein and serum amyloid A protein (SAA) were higher among CAPD patients vs. controls (1.6 ± 2.2 vs. 0.8 ± 1.2 mg/l, p<0.05; 11.9 ± 12.8 vs. 4.5 ± 2.4 mg/l). HPLC analysis revealed that chylomicron, VLDL, and IDL cholesterol levels were higher among CAPD vs. controls. In contrast, HDL cholesterol was lower among CAPD patients vs. controls. In the subgroup analysis, SAA levels were significantly lower among patients receiving CAPD for >3 y than among controls. However, IDL cholesterol was consistently higher among CAPD patients vs. controls.

CONCLUSIONS

CAPD patients have chronic inflammation and dyslipidemia. IDL cholesterol is the only lipoprotein subclass that is consistently elevated regardless of CAPD duration. More attention should be paid to dyslipidemia in the management of the CAPD patients.

Self-management and biomedical outcomes of a cooking, and exercise program for patients with chronic kidney disease

BACKGROUND

Limited research has been done on integrating cooking and exercise classes into the routine care of chronic kidney disease (CKD) patients. The main purpose of the research was to determine whether the addition of these services would slow the progression of certain CKD parameters.

METHODS

The study evaluated 5 endpoints, at baseline, 6 months, and 12 months: urinary protein, blood pressure, urinary sodium, glomerular filtration rate, and total cholesterol between 2 groups (control group receiving CKD standard care and experimental group receiving standard care plus cooking and exercise classes). Eighty percent of the experimental group was hypothesized to improve in 4 out of the 5 endpoints versus ≤50% in the control group with a P-value of 0.05. An overall difference of 30% was anticipated between the 2 groups. The research also compared self-efficacy and health status outcomes using a self-management questionnaire.

RESULTS

Forty randomly assigned patients participated in the study (17 controls and 23 experimental). In the control group, 2 of 17 people improved in at least 4 of the 5 endpoints. In the experimental group, 14 of 23 people improved in at least 4 of the 5 endpoints.

CONCLUSIONS

Sixty-one percent of experimental subjects showed improvements in 4 of 5 endpoints, showing a significant difference overall when compared with the control group (12% improved in 4 out of 5 endpoints). In looking at the trend in qualitative measures from the comparison of the self-management questionnaire, the overall trend showed more improved answers with the experimental group versus the control group.

Association of the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio and concentrations of plasma lipids with high-density lipoprotein subclass distribution in the Chinese population

BACKGROUND

To evaluate the relationship between the low-density lipoprotein cholesterol (LDL-C)/high-density lipoprotein cholesterol (HDL-C) ratio and HDL subclass distribution and to further examine and discuss the potential impact of LDL-C and HDL-C together with TG on HDL subclass metabolism.

RESULTS

Small-sized prebeta1-HDL, HDL3b and HDL3a increased significantly while large-sized HDL2a and HDL2b decreased significantly as the LDL-C/HDL-C ratio increased. The subjects in low HDL-C level (< 1.03 mmol/L) who had an elevation of the LDL-C/HDL-C ratio and a reduction of HDL2b/prebeta1-HDL regardless of an undesirable or high LDL-C level. At desirable LDL-C levels (< 3.34 mmol/L), the HDL2b/prebeta1-HDL ratio was 5.4 for the subjects with a high HDL-C concentration (> or = 1.55 mmol/L); however, at high LDL-C levels (> or = 3.36 mmol/L), the ratio of LDL-C/HDL-C was 2.8 in subjects, and an extremely low HDL2b/prebeta1-HDL value although with high HDL-C concentration.

CONCLUSION

With increase of the LDL-C/HDL-C ratio, there was a general shift toward smaller-sized HDL particles, which implied that the maturation process of HDL was blocked. High HDL-C concentrations can regulate the HDL subclass distribution at desirable and borderline LDL-C levels but cannot counteract the influence of high LDL-C levels on HDL subclass distribution.

Lipid and lipoprotein metabolism in chronic kidney disease

The risk of cardiovascular events and mortality increases as renal function declines although the relative risk of mortality contributed by the standard Framingham risk factors are altered or replaced. Low-density lipoprotein (LDL) cholesterol does not predict mortality but low high-density lipoprotein (HDL) cholesterol and triglycerides remain risk factors. The lipoproteins within each class are shifted to smaller, more dense isoforms. The accumulation of apolipoprotein B-containing lipoproteins, including lipoprotein(a) results primarily from decreased clearance rather than from increased synthesis. Lipoprotein(a) levels are also associated with cardiovascular outcome among dialysis patients. Decreased clearance of very low-density lipoprotein and intermediate-density lipoprotein is a result of decreased lipoprotein lipase, structural alterations in the lipoproteins rendering them poorer substrates, and a decrease in receptor number for these proteins. HDL levels are decreased as a result of an increased fractional catabolic rate both among obese patients with normal renal function and among dialysis patients, but the mechanisms responsible for increased HDL fractional catabolic rate may differ. In patients with advanced kidney disease, HDL fails to mature normally as a result of decreased lecithin cholesterol ester transfer protein, leaving cholesterol ester-poor, triglyceride-rich HDL(3) and pre-beta HDL. HDL in patients with chronic kidney disease is a less effective antioxidative agent than is HDL from normal subjects because of a decrease in paroxonase activity, allowing the accumulation of oxidized LDL.

Mechanisms for increased cardiovascular disease in chronic kidney dysfunction

PURPOSE OF REVIEW

Patients with chronic kidney disease (CKD) have the highest risk for atherosclerotic cardiovascular disease (CVD). Current interventions have been insufficiently effective in lessening excess incidence and mortality from CVD in patients with CKD versus other high-risk groups. This review focuses on traditional and CKD-related risks as well as key mechanisms of macrophage foam cell formation that underlie the excess CVD in the setting of CKD.

RECENT FINDINGS

Hyperlipidemia, particularly increased low-density lipoprotein (LDL) cholesterol, is the key factor in atherogenesis in the general population, but has not been found to be the overriding risk for greater CVD in CKD, especially as renal damage progresses. Although higher incidence of CVD in CKD is not due to higher serum lipids per se, CKD is associated with abnormal lipid metabolism that is proatherogenic. CKD-related risks, including inflammation and disturbances in mineral metabolism, have been implicated. In addition, perturbations of the macrophage, a cell that is central in atherogenesis, may be important.

SUMMARY

The mechanisms underlying the heightened risk for CVD in CKD have been the focus of intense study and may relate to the combined effects of traditional and CKD-specific risks involving inflammation and lipid metabolism, especially perturbation of macrophage cholesterol homeostasis.

Formation of prebeta1-HDL during lipolysis of triglyceride-rich lipoprotein

Prebeta1-HDL, a putative discoid-shaped high-density lipoprotein (HDL) is known to participate in the retrieval of cholesterol from peripheral tissues. In this study, to clarify potential sources of this lipoprotein, we conducted heparin injection on four Japanese volunteer men and found that serum triglyceride (TG) level decreased in parallel with the increase in serum nonesterified fatty acids and plasma lipoprotein lipase (LPL) protein mass after heparin injection. Plasma prebeta1-HDL showed considerable increases at 15 min after the heparin injection in all of the subjects. In contrast, serum HDL-C levels did not change. Gel filtration with fast protein liquid chromatography system (FPLC) study on lipoprotein profile revealed that in post-heparin plasma, low-density lipoprotein and alphaHDL fractions did not change, whereas there was a considerable decrease in very low-density lipoprotein (VLDL) fraction and an increase in prebeta1-HDL fraction when compared with those in pre-heparin plasma. We also conducted in vitro analysis on whether prebeta1-HDL was produced during VLDL lipolysis by LPL. One hundred microliters of VLDL extracted from pooled serum by ultracentrifugation was incubated with purified bovine milk LPL at 37 degrees C for 0-120 min. Prebeta1-HDL concentration increased in a dose dependent manner with increased concentration of added LPL in the reaction mixture and with increased incubation time, indicating that prebeta1-HDL was produced during lipolysis of VLDL by LPL. Taken these in vivo and in vitro analysis together, we suggest that lipolysis of VLDL particle by LPL is an important source for formation of prebeta1-HDL.

Plasma pre beta1-HDL level is elevated in unstable angina pectoris

Pre beta1-HDL, a minor HDL subfraction consisting of apolipoprotein A-I (apoA-I), phospholipids and unesterified cholesterol, plays an important role in reverse cholesterol transport. Plasma pre beta1-HDL levels have been reported to be increased in patients with coronary artery disease (CAD) and dyslipidemia. To clarify the clinical significance of measuring plasma pre beta1-HDL levels, we examined those levels in 112 patients with CAD, consisting of 76 patients with stable CAD (sCAD) and 36 patients with unstable angina pectoris (uAP), and in 30 patients without CAD as controls. The pre beta1-HDL levels were determined by immunoassay using a specific monoclonal antibody (Mab55201) that we established earlier. The mean pre beta1-HDL level in the CAD patients was significantly higher than the level in the controls (34.8+/-12.9 mg/L vs. 26.6+/-6.9 mg/L, p<0.001). In addition, the mean pre beta1-HDL level was markedly higher in the uAP subgroup than in the sCAD subgroup (43.1+/-11.5mg/L vs. 30.9+/-11.7 mg/L, p<0.0001). These tendencies remained even after excluding dyslipidemic subjects. These results suggest that elevation of the plasma pre beta1-HDL level is associated with the atherosclerotic phase of CAD and may be useful for identifying patients with uAP.

Hyperlipidemia in chronic kidney disease

The risk of cardiovascular events and mortality increases as renal function declines. The standard Framingham risk factors contributing to the relative risk of mortality (RRM) are altered or replaced. While obesity predicts loss of renal function, among dialysis patients obesity predicts survival rather than mortality. Among dialysis patients, Low Density Lipoprotein cholesterol (LDL) does not predict mortality; however other risk factors, such as low High Density Lipoprotein cholesterol (HDL) and increased intermediate density lipoproteins (IDL), remain cardiovascular risk factors. While HDL levels are decreased as a result of an increased fractional catabolic rate (FCR) both among obese patients with normal renal function and among dialysis patients, the mechanisms responsible for increased HDL FCR may differ. In patients with advanced kidney disease, HDL fails to mature normally as a result of decreased lecithin cholesterol ester transfer protein (LCAT), leaving cholesterol ester-poor, triglyceride (TG)-rich HDL3 and pre-beta-HDL. Chronic kidney disease (CKD) is associated with insulin resistance, providing another potential mechanistic link to low HDL levels. Increased TG levels are found in an expanded Intermediate Density Lipoprotein (IDL) pool and are associated with mortality risk. Lipoprotein (a) (LP(a)) levels are increased. In patients without renal disease, the concentration of Lp(a) is inversely associated with the size of the apo (a) isoform inherited; Lp (a) levels are increased in patients with kidney disease as consequence of increased concentrations, primarily of the high molecular weight isoform resulting from decreased clearance. Lp (a) levels are also associated with cardiovascular outcome among dialysis patients.

GFR, Body Mass Index, and Low High-Density Lipoprotein Concentration in Adults With and Without CKD

BACKGROUND

Low high-density lipoprotein (HDL) cholesterol level is common in patients with chronic kidney disease, but associations between severity of chronic kidney disease, obesity, and HDL level have not been well defined.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

Within a large integrated health care delivery system, we identified all adult individuals without diabetes who had measured kidney function (estimated glomerular filtration rate [eGFR]), body mass index (BMI), and HDL level, but no substantial proteinuria, confounding medications, or prior renal replacement therapy.

PREDICTORS

The primary predictors for our analyses were eGFR and BMI.

OUTCOMES

Low HDL cholesterol level was the outcome. We performed multivariable logistic regression to investigate whether the relationship between BMI and low HDL level (men, <40 mg/dL; women, <50 mg/dL) varied as a function of eGFR.

RESULTS

Of 380,207 individuals who met cohort entry criteria, there were 26,089 (7%) with chronic kidney disease by eGFR level. Compared with eGFR of 60 mL/min/1.73 m(2) or greater, lower eGFR category (in mL/min/1.73 m(2)) was associated with an increased adjusted odds of low HDL level independent of BMI and other confounders. However, there was a significant interaction between eGFR and BMI (P < 0.001). In separate models stratified by eGFR category (>or=60, 45 to 59, and 30 to 44 mL/min/1.73 m(2)), greater BMI was associated with a graded increased adjusted odds of low HDL level in each eGFR category, but this relationship was attenuated in patients with lower eGFR.

LIMITATIONS

Information for undiagnosed diabetes and proteinuria was unavailable.

CONCLUSIONS

Decreased eGFR is independently associated with greater odds of having a low HDL level. Across a spectrum of eGFR, greater BMI was associated with lower HDL level, but the magnitude of this association was diminished at lower eGFR, suggesting that other factors may also contribute to low HDL levels in patients with advanced chronic kidney disease.