High-density lipoprotein functionality in cholesterol efflux in early childhood is related to the content ratio of triglyceride to cholesterol.

Cholesterol efflux capacity (CEC), commonly measured as a useful risk marker of atherosclerotic cardiovascular disease, depends on high-density lipoprotein (HDL) functionality and its concentration. We defined the relative HDL functionality in cholesterol efflux, not influenced by HDL concentration, as the ratio of measured CEC to standardized CEC (stCEC) based on HDL-cholesterol (HDL-C) of each individual using the curve regression equation obtained from the correlation. HDL-C, CEC, and CEC/stCEC levels in the < 28-day-old participants (neonates) were significantly low compared to those of the ≥ 28-day-old participants, indicating that the low CEC levels in the neonates depend on not only lower HDL-C but also lower HDL functionality. The low level of CEC/stCEC was remarkable in neonates born at < 34 weeks of gestation and did not improved to the reference level (1.000) until the infantile period. The relatively low or high CEC/stCEC ratios in neonates and infants were associated with lower or higher HDL-TG and HDL-TG/HDL-C ratio, respectively. However, no apparent effect of HDL-TG and HDL-TG/HDL-C ratio on CEC/stCEC was observed in the ≥ 1-year-old participants, indicating that HDL functionality in cholesterol efflux could be associated with the various HDL particles with various lipid compositions, but not just with HDL-TG and HDL-TG/HDL-C ratio.

Relation between peripheral blood inflammatory indices and severity of central retinal artery occlusion.

Background: Central retinal artery occlusion (CRAO) has been identified as an acute emergency resulting in vision loss, with its pathogenesis potentially involving systemic inflammation and abnormal lipid metabolism. Over recent years, it has been established that peripheral blood inflammatory indices, including the neutrophil-to-lymphocyte ratio (NLR), the systemic immunoinflammatory index (SII), and the monocyte-to-high-density lipoprotein ratio (MHR), play significant roles in assessing systemic inflammation and lipid metabolism. However, the role of these indices in assessing the severity of CRAO has rarely been explored. This study aimd to investigate the relationship between these inflammatory indices and the severity of CRAO. Methods: This was a retrospective clinical study with a total of 49 CRAO patients and 50 age- and sex-matched controls involved. The patients with CRAO were divided into three groups (13 with incomplete CRAO, 16 with subtotal CRAO and 20 with total CRAO). Data were compared across these groups, and additionally, correlation analysis, restricted cubic spline plots, and receiver operating characteristic curve analysis were performed. Results: The values of NLR, SII and MHR were significantly higher in the CRAO group compared to controls (NLR: 2.49(1.71,3.44) vs 1.60(1.24,1.97), P<0.001; SII: 606.46(410.25,864.35) vs 403.91(332.90,524.31), P=0.001; MHR: 0.33(0.26,0.44) vs 0.25(0.21,0.34), P<0.001). MHR was also significantly higher in total CRAO than in incomplete CRAO and subtotal CRAO (0.41(0.32,0.60) vs 0.29(0.21,0.43), P=0.036; 0.41(0.32,0.60) vs 0.29(0.23,0.38), P=0.017). Significant positive associations were found between MHR, NLR, SII and both the incidence (all P<0.001) and severity (P<0.001, P<0.001, P=0.003, respectively) of CRAO. MHR had a linear relationship with both the occurrence and severity of CRAO (P-overall=0.013, P-non-linear=0.427 and P-overall=0.013, P-non-linear=0.825). Combining MHR and NLR significantly improved diagnostic efficacy for CRAO and total CRAO, with area under the curve of 0.816 and 0.827, respectively, compared to using MHR alone (0.705 and 0.816). Conclusion: Elevated levels of peripheral blood NLR, SII, and MHR are positively associated with CRAO incidence, highlighting their potential as early predictive markers. The combined NLR and MHR index further enhances diagnostic accuracy and may facilitate timely assessment of CRAO severity by ophthalmologists and internists.

The association between serum HDL levels and infertility among American women aged 20-44 years: A retrospective cross-sectional study of NHANES, 2013-2020.

BACKGROUND: Infertility is a significant national public health concern, and the World Health Organization (WHO) predicts that it will rank as the third most prevalent disease following tumors, cardiovascular and cerebrovascular diseases. The impact of dysfunctional lipoproteins on female infertility remains relatively understudied; therefore, the research focuses on exploring the relationship between serum high-density lipoprotein (HDL) concentration and infertility. METHODS: This is a retrospective cross-sectional study where we employed multivariate logistic regression analysis to examine the association between serum HDL concentrations and female infertility. The strength of association was quantified using odds ratios (OR) along with their corresponding 95% confidence intervals and statistical significance was evaluated at a level of P < 0.05 (two-tailed). RESULTS: The study found that there was a significant correlation between serum HDL and infertility without adjusting the model (OR = 0.62, 95%CI 0.48-0.82, P<0.001). After adjusting for covariates, a weak correlation between HDL and infertility remained (OR = 0.70, 95%CI 0.49-1.00). When HDL concentrations were divided into quartiles, there was a trend of strengthened correlation between HDL and infertility risk with the increase in HDL concentrations. Specifically, individuals in the highest concentration quartile exhibited a 44.0% lower risk of infertility compared to those in the lowest concentration quartile (95% CI 0.38-0.84). In the age-stratified analysis, after adjusting for covariates, the correlation between HDL and infertility was statistically insignificant across all age groups. Furthermore, after categorizing HDL levels into quartiles, we observed a dose-dependent trend between HDL and the reduction of female infertility risk in the adjusted models of the secondary infertility group. Specifically, in the adjusted model, the high-concentration group exhibited a 67.0% lower risk of infertility compared to the low-concentration group (OR = 0.33; 95% CI: 0.12-0.940, P = 0.04). CONCLUSION: Our research findings suggest weak negative correlation between serum HDL and female infertility. However, upon stratified analysis by age, the correlation between HDL and infertility did not attain statistical significance. In cases of secondary infertility, a subtle dose-dependent trend was observed between serum HDL and infertility.

Association between high-density lipoprotein-related inflammation index and periodontitis: insights from NHANES 2009-2014.

BACKGROUND: Periodontitis, a persistent inflammatory condition, significantly impairs individuals' overall quality of life. Lymphocyte-to-high-density lipoprotein cholesterol ratio (LHR), monocyte-to-high-density lipoprotein cholesterol ratio (MHR), neutrophil-to-high-density lipoprotein cholesterol ratio (NHR), and platelet-to-high-density lipoprotein cholesterol ratio (PHR) are new convenient and economical biomarkers. However, whether the above high-density lipoprotein-related inflammatory biomarkers are associated with periodontitis has rarely been investigated. Therefore, the research endeavor focused on uncovering potential relationships. METHODS: The research encompassed a diverse and extensive sample, comprising 9,470 participants, selected from the National Health and Nutrition Examination Survey spanning the years 2009 to 2014. The association between high-density lipoprotein-related inflammatory biomarkers and periodontitis was explored utilizing a multivariable logistic regression model with weighted analysis. Additionally, the study employed smoothed curve fitting to explore potential nonlinear relationships. Further stratified analyses and interaction tests were performed. RESULTS: This study indicated no apparent association between MHR and PHR with periodontitis, whereas LHR and NHR demonstrated a statistically significant positive relationship with the prevalence of periodontitis. In the fully adjusted model, participants belonging to the highest tertile of both LHR and NHR showed a notably higher likelihood of having periodontitis compared to those in the lowest tertile (LHR: OR = 1.22, 95% CI: 1.06, 1.39; NHR: OR = 1.27, 95% CI: 1.09, 1.49). Furthermore, smooth curve fitting was employed to investigate the potential nonlinear relationship between LHR, NHR, and periodontitis. The results indicated that there was a significant increase in the occurrence of periodontitis when Log2 (LHR) exceeded 1.01 and Log2(NHR) surpassed 2.16 (Log2(LHR): OR = 1.42; 95% CI: 1.19, 1.69; Log2(NHR): OR = 1.40; 95% CI: 1.15, 1.71). The subgroup analysis revealed that the associations between periodontitis and either LHR or NHR, separately, were more pronounced among individuals under the age of 50 and those without hypertension. CONCLUSIONS: This cross-sectional study revealed a positive relationship between LHR、NHR and periodontitis, particularly when these indicators exceeded their thresholds. LHR and NHR may serve as potential inflammatory markers for identifying periodontitis, thereby facilitating early warning for both patients and dentists, and enabling early intervention in the oral environment. Besides, extensive prospective cohort investigations are essential to confirm and solidify this observation.

Impact of gluten-free diet (GFD) on some of cardiovascular risk factors: a systematic review and meta-analysis.

A gluten-free diet (GFD) may have a stronger potential impact on reducing cardiovascular (CV) risk factors, according to research evidence. We investigated the impact of GFD on CV risk variables by doing a systematic review and meta-analysis for this reason. We conducted a thorough database search starting on January 1, 2000, and ending on July 12, 2022. We used random-effects models to pool the data. Totally 19 articles met the eligible criteria and were included. Pooled findings indicated that intervention with GFD has a significantly beneficial effect on high-density lipoprotein (HDL) (WMD: 4.80 mg/dl, 95% CI: 2.09, 7.51, P = 0.001), systolic blood pressure (SBP) (WMD: -2.96 mmHg; 95% CI: -4.11, -1.81, P < 0.001), and C-reactive protein (CRP) (WMD: -0.40, mg/l, 95% CI: -0.67, -0.14, P = 0.002) levels. In celiac patients as well as with an intervention duration of more than 48 weeks, GFD increased TC and HDL compared to non-celiac patients and with an intervention duration lower than 48 weeks, respectively. The results of the present study showed that GFD can have a significant and beneficial effect on HDL, SBP, and CRP.

Establishment and validation of a nomogram model containing a triglyceride-glucose index and neutrophil-to-high-density lipoprotein ratio for predicting major adverse cardiac events in patients with ST-segment elevation myocardial infarction.

OBJECTIVE: To analyze the predictive value of the triglyceride-glucose (TyG) index and neutrophil-to-high-density lipoprotein ratio (NHR) for in-hospital major adverse cardiac events (MACE) after percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI), and to establish an associated nomogram model. METHODS: In this retrospective study, we collected data from consecutive STEMI patients who underwent PCI from October 2019 to June 2023 at the Second People's Hospital of Hefei and the Second Affiliated Hospital of Anhui Medical University, as training and validation sets. Stepwise regression and multivariate logistic regression analysis were performed to screen independent risk factors, and a nomogram model was constructed and evaluated for its predictive efficacy. RESULTS: The TyG index, NHR, urea, diastolic blood pressure, hypertension, and left ventricular ejection fraction were independent risk factors for in-hospital MACE after PCI, and were used to construct the nomogram model. The C-index of the training and validation sets were 0.799 and 0.753, respectively, suggesting that the model discriminated well. Calibration and clinical decision curves also demonstrated that the nomogram model had good predictive power. CONCLUSION: In STEMI patients, increased TyG index and NHR were closely related to the occurrence of in-hospital MACE after PCI. Our constructed nomogram model has some value for predicting the occurrence of in-hospital MACE in STEMI patients.

Two-way Dispatched function in Sonic hedgehog shedding and transfer to high-density lipoproteins.

The Sonic hedgehog (Shh) signaling pathway controls embryonic development and tissue homeostasis after birth. This requires regulated solubilization of dual-lipidated, firmly plasma membrane-associated Shh precursors from producing cells. Although it is firmly established that the resistance-nodulation-division transporter Dispatched (Disp) drives this process, it is less clear how lipidated Shh solubilization from the plasma membrane is achieved. We have previously shown that Disp promotes proteolytic solubilization of Shh from its lipidated terminal peptide anchors. This process, termed shedding, converts tightly membrane-associated hydrophobic Shh precursors into delipidated soluble proteins. We show here that Disp-mediated Shh shedding is modulated by a serum factor that we identify as high-density lipoprotein (HDL). In addition to serving as a soluble sink for free membrane cholesterol, HDLs also accept the cholesterol-modified Shh peptide from Disp. The cholesteroylated Shh peptide is necessary and sufficient for Disp-mediated transfer because artificially cholesteroylated mCherry associates with HDL in a Disp-dependent manner, whereas an N-palmitoylated Shh variant lacking C-cholesterol does not. Disp-mediated Shh transfer to HDL is completed by proteolytic processing of the palmitoylated N-terminal membrane anchor. In contrast to dual-processed soluble Shh with moderate bioactivity, HDL-associated N-processed Shh is highly bioactive. We propose that the purpose of generating different soluble forms of Shh from the dual-lipidated precursor is to tune cellular responses in a tissue-type and time-specific manner.

Increased oxidative stress biomarkers in central serous chorioretinopathy.

Current data suggest that oxidative stress may play an important role in the occurrence of acute central serous chorioretinopathy (CSC), as chorioretinal integrity may be affected by disruption of the patient's metabolic redox balance, indicating the need for biomarkers. In addition to oxidative stress, high-density lipoprotein (HDL) dysfunction due to dyslipidemia can also lead to many types of physical discomfort. However, little is known about the pathophysiology of the disease resulting from oxidative stress and HDL dysfunction in CSC. The aim of this study was to investigate whether serum oxidative stress and HDL functionality markers have an impact on CSC disease. The case series of this study included 33 consecutive patients with treatment-naïve acute CSC. Thirty-five healthy volunteers of similar age were included in this study as non-CSC controls. Serum samples of the participants were taken and routine lipid values, serum Total Antioxidant Status (TAS), Total Oxidant Status (TOS), Oxidized Low Density Lipoprotein (ox-LDL), and Paraoxonase (PON1) levels were measured quantitatively. Serum oxidative stress index (OSI) was then calculated. Serum Ox-LDL, TOS and OSI levels in the acute CSC group, consisting of patients who had never been treated before and had no other disease, were statistically significantly higher than the control group. Conversely, serum PON1 and TAS levels were lower in CSC than in the control group. The relationship between CSC and deterioration in serum redox balance and decrease in PON1 activity, an important marker of HDL functionality, was demonstrated for the first time through this study. According to the literature, serum levels of these biomarkers, which identify acute/chronic inflammation and oxidative stress, have not been measured before in CSC disease. Finally, it is conceivable that redox balance and HDL functionality may be important in the diagnosis and treatment of the acute phase of CSC.

Molecular mechanisms of the regulatory action of high-density lipoproteins on the endothelial function.

Endothelial dysfunction underlies the pathogenesis of many diseases, primarily cardiovascular diseases. Epidemiological studies have shown an inverse dependence between the plasma level of high-density lipoproteins (HDL) and cardiovascular diseases. The results of experimental studies indicate that the antiatherogenic effect of HDL is associated not only with their participation in the reverse transport of excess cholesterol, but also with their regulatory effect on the functions of cells of various organs and tissues, including endothelial cells. The purpose of this review is to consider recent data on the participation of plasma receptors and related intracellular signaling pathways in the mechanism of protective effect of HDL on endothelial cell functions. Understanding the mechanisms of cell function regulation under the influence of HDL is an important step for the development of new ways of pharmacological correction of impaired endothelial functions and creation of effective endothelial protection drugs.

Impaired HDL antioxidant and anti-inflammatory functions are linked to increased mortality in acute heart failure patients.

AIMS: Acute heart failure (AHF) is typified by inflammatory and oxidative stress responses, which are associated with unfavorable patient outcomes. Given the anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL), this study sought to examine the relationship between impaired HDL function and mortality in AHF patients. The complex interplay between various HDL-related biomarkers and clinical outcomes remains poorly understood. METHODS: HDL subclass distribution was quantified by nuclear magnetic resonance spectroscopy. Lecithin-cholesterol acyltransferase (LCAT) activity, cholesterol ester transfer protein (CETP) activity, and paraoxonase (PON-1) activity were assessed using fluorometric assays. HDL-cholesterol efflux capacity (CEC) was assessed in a validated assay using [3H]-cholesterol-labeled J774 macrophages. RESULTS: Among the study participants, 74 (23.5 %) out of 315 died within three months after hospitalization due to AHF. These patients exhibited lower activities of the anti-oxidant enzymes PON1 and LCAT, impaired CEC, and lower concentration of small HDL subclasses, which remained significant after accounting for potential confounding factors. Smaller HDL particles, particularly HDL3 and HDL4, exhibited a strong association with CEC, PON1 activity, and LCAT activity. CONCLUSIONS: In patients with AHF, impaired HDL CEC, HDL antioxidant and anti-inflammatory function, and impaired HDL metabolism are associated with increased mortality. Assessment of HDL function and subclass distribution could provide valuable clinical information and help identify patients at high risk.

Relationships between HDL subpopulation proteome and HDL function in overweight/obese people with and without coronary heart disease.

BACKGROUND AND AIMS: The structure-function relationships of high-density lipoprotein (HDL) subpopulations are not well understood. Our aim was to examine the interrelationships between HDL particle proteome and HDL functionality in subjects with and without coronary heart disease (CHD). METHODS: We isolated 5 different HDL subpopulations based on charge, size, and apolipoprotein A1 (APOA1) content from the plasma of 33 overweight/obese CHD patients and 33 age-and body mass index (BMI)-matched CHD-free subjects. We measured the relative molar concentration of HDL-associated proteins by liquid chromatography tandem mass spectrometry (LC-MS/MS) and assessed particle functionality. RESULTS: We quantified 110 proteins associated with the 5 APOA1-containing HDL subpopulations. The relative molar concentration of these proteins spanned five orders of magnitude. Only 10 proteins were present in >1% while 73 were present in <0.1% concentration. Only 6 of the 10 most abundant proteins were apolipoproteins. Interestingly, the largest (α-1) and the smallest (preß-1) HDL particles contained the most diverse proteomes. The protein composition of each HDL subpopulation was altered in CHD cases as compared to controls with the most prominent differences in preß-1 and α-1 particles. APOA2 concentration was positively correlated with preß-1 particle functionality (ABCA1-CEC/mg APOA1 in preß-1) (R2 = 0.42, p = 0.005), while APOE concentration was inversely correlated with large-HDL particle functionality (SRBI-CEC/mg APOA1 in α-1+α-2) (R2 = 0.18, p = 0.01). CONCLUSIONS: The protein composition of the different HDL subpopulations was altered differentially in CHD patients. The functionality of the small and large HDL particles correlated with the protein content of APOA2 and APOE, respectively. Our data indicate that distinct particle subspecies and specific particle associated proteins provide new information about the role of HDL in CHD.

Low platelet to high-density lipoprotein ratio predicts poor short-term prognosis in hepatitis B-related acute-on-chronic liver failure.

BACKGROUND: Acute-on-chronic liver failure (ACLF) is characterized by a systemic inflammatory response, predominantly associated with hepatitis B virus in the Asia-Pacific region, with a high short-term mortality rate. The platelet to high-density lipoprotein ratio (PHR) has been used to predict the prognosis of patients with various inflammatory diseases. We aim to is to use the PHR to predict the short-term prognosis of patients with HBV-ACLF. METHOD: In this study, we retrospectively analyzed clinical data from 270 HBV-ACLF patients. Using logistic regression, we identified independent risk factors for short-term mortality and developed a prognostic model. This model was then validated, compared, and its clinical utility assessed via decision curve analysis (DCA). RESULTS: Among the 270 HBV-ACLF patients, 98 patients died within 28 days. The deceased group exhibited a higher proportion of severe hepatic encephalopathy and ascites. Additionally, there was a statistically significant difference (P = 0.046) in the novel inflammation scoring system, PHR, between the two groups. Following stringent variable selection, PHR was identified as a predictive factor for short-term mortality in HBV-ACLF patients using logistic regression analysis (OR: 0.835 (0.756-0.999), P = 0.009), and it exhibited a synergistic effect with certain traditional scores. The prognostic model constructed based on PHR demonstrated a superior ability to predict short-term mortality compared to traditional scores such as Child-Turcotte-Pugh (AUC: 0.889). Evaluation using calibration curves and decision curve analysis (DCA) suggested its practical utility. CONCLUSION: PHR can predict short-term mortality in patients, with a low PHR upon admission being associated with an increased risk of death.

Proteomic Profiling of HDL in Newly Diagnosed Breast Cancer Based on Tumor Molecular Classification and Clinical Stage of Disease.

The association between high-density lipoprotein (HDL) cholesterol and breast cancer (BC) remains controversial due to the high complexity of the HDL particle and its functionality. The HDL proteome was determined in newly diagnosed BC classified according to the molecular type [luminal A or B (LA or LB), HER2, and triple-negative (TN)] and clinical stage of the disease. Women (n = 141) aged between 18 and 80 years with BC, treatment-naïve, and healthy women [n = 103; control group (CT)], matched by age and body mass index, were included. Data-independent acquisition (DIA) proteomics was performed in isolated HDL (D = 1.063-1.21 g/mL). Results: Paraoxonase1, carnosine dipeptidase1, immunoglobulin mMu heavy chain constant region (IGHM), apoA-4, and transthyretin were reduced, and serum amyloid A2 and tetranectin were higher in BC compared to CT. In TNBC, apoA-1, apoA-2, apoC-2, and apoC-4 were reduced compared to LA, LB, and HER2, and apoA-4 compared to LA and HER2. ComplementC3, lambda immunoglobulin2/3, serpin3, IGHM, complement9, alpha2 lysine rich-glycoprotein1, and complement4B were higher in TNBC in comparison to all other types; complement factor B and vitamin D-binding protein were in contrast to LA and HER2, and plasminogen compared to LA and LB. In grouped stages III + IV, tetranectin and alpha2-macroglobulin were reduced, and haptoglobin-related protein; lecithin cholesterol acyltransferase, serum amyloid A1, and IGHM were increased compared to stages I + II. Conclusions: A differential proteomic profile of HDL in BC based on tumor molecular classification and the clinical stage of the disease may contribute to a better understanding of the association of HDL with BC pathophysiology, treatment, and outcomes.

Reconstituted HDL ameliorated renal injury of diabetic kidney disease in mice.

Diabetic kidney disease (DKD) is a devastating kidney disease and lacks effective therapeutic interventions. The present study was aimed to determine whether reconstituted high-density lipoprotein (rHDL) ameliorated renal injury in eNOS-/- dbdb mice, a mouse model of DKD. Three groups of mice, wild type C57BLKS/J (non-diabetes), eNOS-/- dbdb (diabetes), and eNOS-/- dbdb treated with rHDL (diabetes+rHDL) with both males and females were used. The rHDL nanoparticles were administered to eNOS-/- dbdb mice at Week 16 at 5 µg/g body weight in ~100 µL of saline solution twice per week for 4 weeks via retroorbital injection. We found that rHDL treatment significantly blunted progression of albuminuria and GFR decline observed in DKD mice. Histological examinations showed that the rHDLs significantly alleviated glomerular injury and renal fibrosis, and inhibited podocyte loss. Western blots and immunohistochemical examinations showed that increased protein abundances of fibronectin and collagen IV in the renal cortex of eNOS-/- dbdb mice were significantly reduced by the rHDLs. Taken together, the present study suggests a renoprotective effect of rHDLs on DKD.

Association of HDL and LDL levels with osteoporosis in rheumatoid arthritis: a retrospective cohort study.

OBJECTIVES: A correlation exists between lipids and osteoporosis (OP), as well as between lipids and rheumatoid arthritis (RA). However, lipids, the relationship between RA and OP is still unclear. This study mainly investigates the relationship between lipid levels and OP risk in RA patients. METHODS: Retrospective collection of RA patient data from July 2017 to May 2022, encompassing baseline demographics, treatment regimens, laboratory results, and bone mineral density (BMD) measurements. Analyses, stratified by BMD subgroups, were conducted using propensity score matching (PSM) based on age, sex, and baseline duration, and binary logistic regression to examine the interplay between lipoprotein levels and other risk factors. The relationship between continuous variables and OP risk was assessed using restricted cubic spline (RCS), followed by a reanalysis of the correlation between varying lipoprotein levels and different factors, segmented according to RCS-determined cutoffs. RESULTS: The study included 2673 RA patients. Binary logistic regression revealed significant associations between high-density lipoprotein (HDL), low-density lipoprotein (LDL), and RA-OP (p < 0.01). Specifically, HDL emerged as a protective factor against OP (OR = 0.40, 95% CI 0.250-0.629; p < 0.001), whereas LDL was identified as a risk factor (OR = 1.56, 95% CI 1.290-1.890; p < 0.001). Furthermore, HDL (RCS cutoff point 1.28 mmol/L) showed a negative, linear correlation with RA-related OP, while LDL (RCS cutoff point 2.63 mmol/L) demonstrated a positive, linear correlation. CONCLUSIONS: The levels of HDL and LDL may be indicators of OP occurrence in RA patients.

Foam fractionation studies of recombinant human apolipoprotein A-I.

Apolipoprotein A-I (apoA-I), the primary protein component of plasma high-density lipoproteins (HDL), is comprised of two structural regions, an N-terminal amphipathic α-helix bundle domain (residues 1-184) and a hydrophobic C-terminal domain (residues 185-243). When a recombinant fusion protein construct [bacterial pelB leader sequence - human apoA-I (1-243)] was expressed in Escherichia coli shaker flask cultures, apoA-I was recovered in the cell lysate. By contrast, when the C-terminal domain was deleted from the construct, large amounts of the truncated protein, apoA-I (1-184), were recovered in the culture medium. Consequently, following pelB leader sequence cleavage in the E. coli periplasmic space, apoA-I (1-184) was secreted from the bacteria. When the pelB-apoA-I (1-184) fusion construct was expressed in a 5 L bioreactor, substantial foam production (~30 L) occurred. Upon foam collection and collapse into a liquid foamate, SDS-PAGE revealed that apoA-I (1-184) was the sole major protein present. Incubation of apoA-I (1-184) with phospholipid vesicles yielded reconstituted HDL (rHDL) particles that were similar in size and cholesterol efflux capacity to those generated with full-length apoA-I. Mass spectrometry analysis confirmed that pelB leader sequence cleavage occurred and that foam fractionation did not result in unwanted protein modifications. The facile nature and scalability of bioreactor-based apolipoprotein foam fractionation provide a novel means to generate a versatile rHDL scaffold protein.

Genome-wide association study for metabolic syndrome reveals APOA5 single nucleotide polymorphisms with multilayered effects in Koreans.

BACKGROUND AND PURPOSE: Genome-wide association studies (GWAS) of metabolic syndrome (MetS) have predominantly focused on non-Asian populations, with limited representation from East Asian cohorts. Moreover, previous GWAS analyses have primarily emphasized the significance of top single nucleotide polymorphisms (SNPs), poorly explaining other SNP signals in linkage disequilibrium. This study aimed to reveal the interaction between rs651821 and rs2266788, the principal variants of apolipoprotein A5 (APOA5), within the most significant loci identified through GWAS on MetS. METHODS: GWAS on MetS and its components was conducted using the data from the Korean Genome and Epidemiology Study (KoGES) city cohort comprising 58,600 individuals with available biochemical, demographic, lifestyle factors, and the most significant APOA5 locus was analyzed further in depth. RESULTS: According to GWAS of MetS and its diagnostic components, a significant association between the APOA5 SNPs rs651821/rs2266788 and MetS/triglycerides/high-density lipoprotein phenotypes was revealed. However, a conditional analysis employing rs651821 unveiled a reversal in the odds ratio for rs2266788. Therefore, rs651821 and rs2266788 emerged as independent and opposing signals in the extended GWAS analysis, i.e., the multilayered effects. Further gene-environment interaction analyses regarding lifestyle factors such as smoking, alcohol consumption, and physical activity underscored these multilayered effects. CONCLUSION: This study unveils the intricate interplay between rs651821 and rs2266788 derived from MetS GWAS. Removing the influence of lead SNP reveals an independent protective signal associated with rs2266788, suggesting a multilayered effect between these SNPs. These findings underline the need for novel perspectives in future MetS GWAS.

Quantification of high-density lipoprotein particle number by proton nuclear magnetic resonance: don't believe the numbers.

PURPOSE OF REVIEW: Proton nuclear magnetic resonance (NMR) can rapidly assess lipoprotein concentrations and sizes in biological samples. It may be especially useful for quantifying high-density lipoprotein (HDL), which exhibits diverse particle sizes and concentrations. We provide a critical review of the strengths and limitations of NMR for quantifying HDL subclasses. RECENT FINDINGS: Recent studies using NMR have shed light on HDL's role in various disorders, ranging from residual cardiovascular risk to host susceptibility to infection. However, accurately quantifying HDL particle number, size, and concentration (HDL-P) remains a challenge. Discrepancies exist between NMR and other methods such as gel electrophoresis, ion mobility analysis and size-exclusion chromatography in estimating the abundance of HDL species and the ratio of apolipoprotein A-I (APOA1) to HDL particles. SUMMARY: NMR is a low-cost method for quantifying HDL-P that is readily applicable to clinical and translational studies. However, inconsistencies between the results of NMR quantification of HDL-P and other independent methods hinder the interpretation of NMR results. Because proton NMR apparently fails to accurately quantify the sizes and concentrations of HDL, the relevance of such studies to HDL biology poses challenges. This limits our understanding of pathophysiological implications of HDL-P as determined by NMR, particularly in determining cardiovascular disease (CVD) risk.

ABCA1 deficiency causes tissue-specific dysregulation of the SREBP2 pathway in mice.

ABCA1 plays an essential role in the formation of high-density lipoprotein (HDL), and its mutations cause Tangier disease (TD), a familial HDL deficiency. In addition to the disappearance of HDL, TD patients exhibit cholesterol deposition in peripheral tissues through a mechanism poorly understood, which may contribute to the development of premature atherosclerosis. We and others previously showed that ABCA1 deficiency causes hyperactivation of the SREBP2 pathway in vitro. Here, we show using Abca1 knockout mice that ABCA1 deficiency leads to tissue-specific dysregulation of SREBP2 activity in a nutritional status-dependent manner, which may underlie the pathophysiology of TD.