HDL in Immune-Inflammatory Responses: Implications beyond Cardiovascular Diseases

Benchtop Proton NMR Spectroscopy for High-Throughput Lipoprotein Quantification in Human Serum and Plasma

We report the successful development and translation of high-field nuclear magnetic resonance (NMR) based comprehensive lipoprotein analysis to routine benchtop systems. This demonstrates the potential to reimagine population level cardiovascular disease risk analysis and individual level screening based on blood sampling. Using a quantitative calibration approach, we obtained stable and reproducible results from multiple sites, despite reduced spectral dispersion and sensitivity at lower field strengths. Our study shows that 25 out of 28 major lipoprotein parameters, including key cardiometabolic risk markers, were faithfully measured using benchtop NMR systems within 15 min. This development has significant implications for making a powerful diagnostic tool widely available, enhancing the potential for longitudinal personalized medicine through molecular phenotyping in the clinic.

New perspectives on the high-density lipoprotein system and its role in the prevention and treatment of atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

The causal role of high-density lipoprotein (HDL) in atherosclerotic cardiovascular disease (CVD) remains debated. Considering recent evidence, the purpose of this review is to a provide a focused update and new perspectives on HDL and CVD.

RECENT FINDINGS

A Mendelian randomization study demonstrated an increased risk of CVD when HDL-cholesterol was predominantly transported in larger HDL particles and a decreased risk of CVD when HDL-cholesterol was predominantly transported in smaller HDL particles. Moreover, another Mendelian randomization study demonstrated that concentration and content of medium HDL particles is associated with CVD. A Mendelian randomization study that utilized stratified analyses demonstrated that individuals with HDL-cholesterol 50 mg/dl or less were at increased risk of CVD. Lastly, the AEGIS-II trial demonstrated that CSL112, a human apolipoprotein A-I that increases cholesterol efflux, did not significantly reduce cardiovascular events in patients at very high risk. Exploratory analyses showed that patients treated with CSL112 had numerically lower rates of cardiovascular events.

SUMMARY

Qualitative markers of HDL may be causally related to CVD. There is a need for ongoing research into HDL therapeutics that promote the biological properties of HDL. The optimal cohort or disease state that will benefit from these therapies needs to be identified.

Investigating the binding products between human apolipoproteins and oxidized 1-palmitoyl-2-arachidonyl-sn-glycerol-3-phosphocholine by micellar electrokinetic chromatography

A micellar electrokinetic chromatography (MEKC) method has been developed to investigate the binding products between human apolipoproteins (Apos) and oxidized 1-palmitoyl-2-arachidonoyl-sn‑glycero-3-phosphocholine (ox-PAPC) products. The optimal MEKC separation buffer was composed of a solution mixture of 10 mM sodium phosphate, 50 mM bile salts (50 % sodium cholate and 50 % sodium deoxycholate), 30 % (v/v)1-propanol and 70 % (v/v) water, pH 7.4. The optimal MEKC sample buffer was composed of 70 % (v/v) PBS buffer and 30 % (v/v) MeOH. The selected separation voltage was 20 kV, and the capillary temperature was 25℃. The MEKC profiles of ox-PAPC products showed good separations and repeatability. The MEKC profiles of apos and their binding products also showed good repeatability. For the analysis of native PAPC (n-PAPC), the method is linear in the range of 0.00-6.00 mg/mL with a correlation coefficient 0.9984. The concentration limit of detection (LOD) is 0.29 mg/mL. The concentration limit of quantitation (LOQ) is 0.98 mg/mL. The binding reactions between several important human apolipoproteins (Apos A-I, A-II, C-I, C-II, C-III and E) and native PAPC, ox-PAPC products have been investigated. The concentrations of Apos and ox-PAPC products for binding reactions have been examined. The optimal binding buffer selected was 70 % (v/v) PBS buffer and 30 % (v/v) MeOH. The binding reaction was performed at 37 ℃ for 3 hr. The results indicated that ox-PAPC products bound to Apos A-I, A-II, C-I, and E more strongly than n-PAPC. However, both ox-PAPC products and n-PAPC did not bind to Apos C-II and C-III strongly. The results suggested pro-inflammatory properties of Apos A-I, A-II, C-I, and E, and implied one of the molecular mechanisms resulting in dysfunctional HDL particles. This study also demonstrated the feasibility of investigating the binding reactions between human apolipoproteins and ox-PAPC products by MEKC.

Association between atherogenic index of plasma and chronic diarrhea: a cross-sectional study of the NHANES 2005-2010

BACKGROUND

Chronic diarrhea (CD), a common chronic condition resulting from various mechanisms, has chronic inflammation as a primary determinant. Despite recent research exploring the potential mechanisms linking lipids and diarrhea, clinical studies on the relationship between lipids and the onset of CD are limited. This study aimed to investigate the association between the atherogenic index of plasma (AIP) and CD risk.

METHODS

This cross-sectional study used data from the 2005-2010 NHANES. The association between AIP and CD was examined through multiple linear regression analyses. A smooth curve-fitting algorithm was applied to assess the potential non-linear dose-response relationship between AIP and CD, and subgroup analyses were conducted.

RESULTS

Among 5,948 participants, 440 (7.4%) had CD. After adjusting for potential confounders, AIP was significantly associated with CD (OR, 1.57; 95% CI, 1.08-2.30; P = 0.018). The highest AIP quartile (Q4; 0.18 to 0.92) showed an adjusted OR for CD of 1.51 (95% CI, 1.10-2.07; P = 0.011) versus the lowest quartile (Q1; -1.15 to -0.25). Subgroup analyses indicated that diabetic individuals with higher AIP had a higher CD risk (OR, 3.84; 95% CI, 1.45-10.15), with an observed additive interaction (P for interaction = 0.045).

CONCLUSIONS

This study demonstrates a significant association between AIP and CD risk. AIP may serve as a promising indicator for assessing CD risk, offering valuable insights for prevention and treatment strategies.

Leukocyte telomere length change in children with obesity in the context of an isocaloric fructose restriction intervention

BACKGROUND

Few studies have evaluated changes in leukocyte telomere length (LTL) over a short time period (e.g. 1 week). LTL shortening is accelerated by exposure to inflammation and reactive oxygen species (ROS) damage.

METHODS

In the context of an isocaloric fructose restriction study that was conducted with 43 Black and Latinx children over a 9-day period, we evaluated the relationship between metabolic health at baseline and metabolic changes and LTL at baseline and %LTL change over the follow-up period. Linear regression models were used to assess associations between metabolic correlates and LTL at baseline and LTL changes over 9 days.

RESULTS

Overall children lost - 0.05 ± 0.14 T/S units or - 2.98 ± 8.74% total change over the follow-up period. Higher concentrations of HDL-C, APO-AI and a greater % of large HDL-C at baseline were associated with reduced LTL attrition rates at day 10 (p < 0.01; p < 0.01 and p = 0.02 respectively). Increases in APO-AI over the follow-up period were associated with increased LTL attrition over the follow-up period (p = 0.03).

CONCLUSIONS

In this short term isocaloric fructose restriction study, LTL at baseline and changes in LTL over 9 days were associated with HDL-C and APO-AI and not with any other non-HDL-C lipids. Additional, larger studies are necessary to better understand the interplay between short term fructose restriction, LTL changes and HDL-C/APO-AI.

HDL-replacement therapy: From traditional to emerging clinical applications

The unique and multifaceted properties of high-density lipoproteins (HDL)-ranging from cholesterol efflux to anti-inflammatory, anti-oxidant, and immunomodulatory effects-have prompted their direct use, particularly in cardiovascular ischemic conditions. Recent advances have extended the interest in HDL-based treatments to novel applications, from improving stent biocompatibility, to treatment of heart failure to central nervous system (CNS) disorders. Strategies to harness HDL's therapeutic potential have evolved from the direct use of isolated HDL in animal models to reconstituted HDL (rHDL) in humans. For these latter, the use of isolated apoA-I associated with different phospholipids has been the most frequent approach, also involving apparently beneficial mutants, such as the apo A-I Milano (AIM). From the initial very promising results, particularly with this mutant in coronary patients, later studies have mostly been non-confirmatory, although issues such as possible inadequate dose/response and unexpected immunological properties have come to light. Most recently a study on isolated plasma HDL in coronary patients (AEGIS-II) provided overall negative findings, but a clear fall of major cardiovascular events was recorded when restricting analysis to hypercholesterolemic patients. Emerging approaches, including gene therapy and plant-derived recombinant HDL formulations, hold promise for enhancing the accessibility and efficacy of HDL-based interventions. At this time, an improved approach to heart failure treatment also appears feasible, and a better understanding of the role played by HDL in the CNS may lead to significant improvements in the handling of some dramatic diseases at this level. While challenges persist, the evolving landscape of HDL replacement therapies offers hope for significant progress in addressing both cardiovascular and non-cardiovascular conditions.

The association between triglyceride to high-density-lipoprotein cholesterol ratio and calcific aortic valve disease: a retrospective study

BACKGROUND

The ratio of triglycerides to high-density-lipoprotein cholesterol (TG/HDL-C) is increasingly recognized as a practical marker for insulin resistance and cardiovascular risk assessment. This retrospective study investigates the potential of the TG/HDL-C ratio to predict the development of calcific aortic valve disease (CAVD), thereby extending its applicability in cardiovascular diagnostics.

METHODS

Data from 400 individuals, comprising 200 patients with diagnosed CAVD and 200 matched healthy controls, were analyzed. Clinical parameters were compared between groups, and logistic regression was utilized to explore the association of the TG/HDL-C ratio with CAVD. The diagnostic performance of the TG/HDL-C ratio was assessed using receiver operating characteristic (ROC) curves.

RESULTS

The TG/HDL-C ratio was notably higher in the CAVD group than in the controls (Z = -7.98, P < 0.001). Multivariable logistic regression analysis indicated that the TG/HDL-C ratio is an independent predictor of CAVD after adjusting for confounders including gender. The ROC curve analysis revealed that the TG/HDL-C ratio achieved a sensitivity of 80.5%, a specificity of 59.5%, and an area under the curve (AUC) of 0.731 (P < 0.001), confirming its efficacy in predicting CAVD.

CONCLUSIONS

High TG/HDL-C ratio was significantly associated with the occurrence of CAVD, and the TG/HDL-C ratio could be used as a potential diagnostic tool and risk assessment indicator for CAVD.

CLINICAL TRIAL NUMBER

Not applicable.

Identification of key modules in metabolic syndrome induced by second-generation antipsychotics based on co-expression network analysis

Background

Second-generation antipsychotics (SGAs) frequently cause metabolic syndrome (MetS), which raises the risk of heart disease, type 2 diabetes, morbid obesity, atherosclerosis, and hypertension. MetS also impairs cognitive function in patients with schizophrenia. However, the fundamental reasons of MetS caused by SGAs are not yet fully understood. Thus, we aimed to identify potential therapeutic targets for MetS induced by SGAs.

Methods

The serum biochemical parameters and the RNA-sequencing of peripheral blood mononuclear cells were measured in three groups (healthy controls and patients with schizophrenia with and without MetS taking SGAs). The study of the weighted gene co-expression network was utilized to pinpoint modules that were significantly connected to clinical markers.

Results

Statistical analysis showed significant differences in triglyceride and high-density lipoprotein among the three groups. The TNF signaling pathway, TGF-β signaling pathway, fatty acid metabolism, NF-kappa B signaling pathway, MAPK signaling pathway, and Toll-like receptor signaling pathway were the pathways that were primarily enriched in the two unique co-expression network modules that were found. Finally, five specific genes (TNF, CXCL8, IL1B, TIMP1, and ESR1) associated with metabolism and immunity pathways were identified.

Conclusions

This study indicated that SGAs differentially induced MetS of patients with schizophrenia through metabolic and inflammation-related pathways. Therefore, the potential side effects of drugs on inflammatory processes need to be considered when using SGAs for the treatment of schizophrenia.

Unraveling the Pleiotropic Role of High-Density Lipoproteins (HDLs) in Autoimmune Rheumatic Diseases

Autoimmune rheumatic diseases (ARDs) exhibit an elevated incidence of cardiovascular disease (CVD). The elevation of inflammatory and immune stress accompanying ARDs contributes to atherosclerosis development and alterations in lipid metabolism and lipoprotein profile add to cardiovascular (CV) risk. The plasma concentration of high-density lipoprotein cholesterol (HDLc) is inversely related to CVD and serves as a discriminator of CV risk. However, this association is not unequivocal, and changes in HDL functionality appear to emerge as a better indicator of CV risk, albeit difficult to measure and monitor clinically. The modulation of HDLc itself can bring benefits in controlling autoimmunity and reducing ARD activity. Understanding HDL function and each peculiarity involved in ARDs enables to seek means to prevent ischemic outcomes associated with CVD, in the face of the residual CV risk persisting even with controlled disease activity and classic risk factors. By comprehending HDL's structural and functional nuances, it will be possible to develop more effective strategies to manage the evolution and outcomes of ARDs. It is also necessary to standardize diagnostic methods and establish different markers for each specific disease allowing the design of intervention strategies to restore HDL functionality, reduce residual CV, and prevent, alleviate, or even suppress ARD activity.

The Impact of Acute Ammonia Nitrogen Stress on Serum Biochemical Indicators and Spleen Gene Expression in Juvenile Yellowfin Tuna (Thunnus albacares)

The presence of ammonia nitrogen in water has a significant impact on the serum and spleen of fish, potentially leading to changes in substances such as proteins in the serum while also causing damage to the immune function of the spleen. To investigate the effects of ammonia nitrogen (NH3-N) stress on juvenile yellowfin tuna (Thunnus albacares), this study established three NH3-N concentrations, 0, 5, and 10 mg/L, denoted as L0, L1, and L2, respectively. Serum and spleen samples were collected at 6, 24, and 36 h. The effects of different NH3-N concentrations and exposure times on the physiological status of juvenile fish were investigated by analyzing serum biochemical indices and splenic gene expression. The results indicate that in the L1 group, the serum high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), complement 3 (C3) and complement 4 (C4) levels, and acid phosphatase (ACP) activity showed a trend of initially increasing and then decreasing. In the L2 group, the serum low-density lipoprotein cholesterol (LDL-C), HDL-C, and C4 levels and ACP activity also displayed an initially rising and then declining trend, while TG, C3, and creatinine (CRE) levels and alkaline phosphatase (AKP) activity showed an upward trend. In the L1 group, glutathione peroxidase 1b (GPX1b), interleukin 10 (IL-10), interleukin 6 receptor (IL-6r), and tumor necrosis factor alpha (TNF-α) gene expression levels in the spleen exhibited a trend of first increasing and then decreasing. In the L2 group, IL-10, IL-6r, tumor necrosis factor beta (TNF-β), caspase 2 (casp2), and caspase 9 (casp9) gene expression levels in the spleen also showed an initial increase followed by a decrease. When NH3-N levels are below 5 mg/L, it is recommended to limit stress exposure to no more than 36 h for the juvenile fish. For concentrations ranging from 5 to 10 mg/L, stress should be strictly controlled to within 24 h. Exposure to high NH3-N levels may affect biochemical indicators such as serum lipid metabolism, immunity, and metabolism in juvenile fish, and may damage the expression of antioxidant, immune gene, and apoptosis factors in the spleen. This study aims to deepen our understanding of the effects of NH3-N on juvenile tuna, with the goal of establishing effective water quality monitoring and management strategies. This will ensure the quality of aquaculture water, reduce the harm caused by NH3-N to juvenile yellowfin tuna, and enhance aquaculture efficiency and product quality.

The Composition of the HDL Particle and Its Capacity to Remove Cellular Cholesterol Are Associated with a Reduced Risk of Developing Active Inflammatory Rheumatoid Arthritis

In rheumatoid arthritis (RA), the risk of cardiovascular death is 50% higher compared to the general population. This increased risk is partly due to the systemic inflammation characteristic of RA and changes in the lipoprotein profiles. This study investigated plasma lipid levels, lipid ratios, and the composition and functionality of high-density lipoprotein (HDL) in control individuals and RA subjects based on the disease's inflammatory score (DAS28). This study included 50 control (CTR) individuals and 56 subjects with RA, divided into remission/low-activity disease (DAS28 < 3.2; n = 13) and active disease (DAS28 ≥ 3.2; n = 43). Plasma lipids (total cholesterol, TC; triglycerides, TG) and the HDL composition (TC; TG; phospholipids, PL) were determined using enzymatic methods; apolipoprotein B (apoB) and apoA-1 were measured by immunoturbidimetry. HDL-mediated cholesterol efflux and anti-inflammatory activity were assessed in bone marrow-derived macrophages. Comparisons were made using the Mann-Whitney test, and binary logistic regression was used to identify the predictors of active RA. A p-value < 0.05 was considered significant. TC, HDLc, and the TC/apoB ratio were higher in RA subjects compared to the CTR group. Subjects with active disease exhibited higher levels of TG and the TG/HDLc ratio and lower levels of HDLc, the TG/apoB ratio, TC, and apoA-1 in HDL particles compared to those with remission/low-activity RA. Increased levels of HDLc [odds ratio (OR) 0.931, 95% CI = 0.882-0.984], TC/apoB (OR 0.314, 95% CI = 0.126-0.78), HDL content in TC (OR 0.912, 95% CI = 0.853-0.976), PL (OR 0.973, 95% CI = 0.947-1.000), and apoA-1 (OR 0.932, 95% CI = 0.882-0.985) were associated with a decreased risk of active disease, but BMI (OR 1.169, 95% CI = 1.004-1.360) and TG (OR 1.031, 95% CI = 1.005-1.057) were positively associated with active disease. A reduction in HDL-mediated cholesterol efflux increased the OR for active RA by 26.2%. The plasma levels of HDLc, along with the composition and functionality of HDL, influence the inflammatory score in RA and may affect the development of cardiovascular disease.

Cytokine profiles and their correlation with clinical and blood parameters in rheumatoid arthritis and systemic lupus erythematosus

The abnormal biological activity of cytokines and their imbalance are implicated in developing rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Cytokine levels were measured in RA and SLE patients and compared to healthy controls using the Wilcoxon rank sum test and Kruskal-Wallis test. The relationship between cytokine levels and blood and clinical parameters was assessed using Spearman's correlation test. Compared to healthy controls, both RA and SLE patients exhibited elevated levels of GM-CSF, CX3CL1, IFN-α2, IL-12p70, IL-17A, TNF-α, IL-1β, and IFN-γ, which is evidence of their shared inflammatory signature. IL-2 levels were elevated exclusively in RA patients, while MCP-1 and IL-10 were uniquely increased in SLE patients. Notably, TNF-α showed the most significant increase in SLE patients. IL-4 was elevated in SLE patients with nephritis, correlating with IL-6, IL-10, sCD40L, and IL-8, suggesting B cell involvement in lupus nephritis. The negative correlation between CX3CL1 and TNF-α with HDL in RA and SLE respectively, highlights the potential association of these inflammatory markers with cardiovascular risk. These findings underscore the complex cytokine interplay in RA and SLE. CX3CL1 emerges as a potential therapeutic target for RA, while TNF-α and IL-4 show promise as therapeutic targets for SLE.

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.

Exploring the Association Between Systemic Lupus Erythematosus and High-Density Lipoproteins: A Systematic Review and Meta-Analysis

OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune disease with inflammation as a critical feature. Recently, high-density lipoprotein cholesterol (HDLc) have been evidenced to have anti-inflammatory effects, suggesting a potential link between HDL and SLE that needs to be thoroughly studied. The aim was to explore the association between SLE and HDLc through a systematic review with meta-analysis.

METHODS

A systematic review with meta-analysis was conducted to assess mean differences in HDL levels between patients with SLE and healthy controls. Both qualitative and quantitative syntheses were performed, including an assessment of heterogeneity using I2, a publication bias evaluation, a methodologic quality assessment, and a forest plot under a random effects model. Subgroup analyses were conducted based on disease activity and the report of corticosteroid dosage.

RESULTS

A total of 53 studies were included in the qualitative synthesis, and 35 studies were included in the quantitative synthesis, comprising 3,002 patients with SLE and 2,123 healthy controls. Mean HDL levels were found to be lower in patients with SLE as follows: in the meta-analysis including all articles -6.55 (95% confidence interval [CI] -8.77 to -4.33); in patients with mild disease activity -5.46 (95% CI -8.26 to -2.65); in patients with moderate or severe disease activity -9.42 (95% CI -15.49 to -3.34); in patients using corticosteroids -5.32 (95% CI -10.35 to -0.29); and in studies with excellent methodologic quality -8.71 (95% CI -12.38 to -5.03).

CONCLUSION

HDL levels appear to be quantitatively altered in patients with SLE, suggesting a potential contribution to immune dysregulation, highlighting the importance of HDL in autoimmune diseases.

Impaired high-density lipoprotein function and endothelial barrier stability in severe anaphylaxis

BACKGROUND

Growing evidence demonstrates the importance of high- and low-density lipoprotein cholesterol in certain immune and allergy-mediated diseases.

OBJECTIVE

This study aimed to evaluate levels of high- and low-density lipoprotein cholesterol and apolipoproteins A1 and B in sera from a cohort of patients presenting with hypersensitivity reactions. We further assessed the function of high-density lipoprotein particles as well as their involvement in the molecular mechanisms of anaphylaxis.

METHODS

Lipid profile determination was performed in paired (acute and baseline) serum samples from 153 patients. Thirty-eight experienced a non-anaphylactic reaction and 115 had an anaphylactic reaction (88 moderate and 27 severe). Lecithin cholesterol acyl transferase activity was assessed in patient sera, and we also evaluated macrophage cholesterol efflux in response to the serum samples. Last, the effect of anaphylactic-derived high-density lipoprotein (HDL) particles on the endothelial barrier was studied. Detailed methods are provided in the Methods section in this article's Online Repository available at www.jacionline.org.

RESULTS

Serum samples from severe anaphylactic reactions show statistically significant low levels of HDL cholesterol, low-density lipoprotein cholesterol, and apolipoproteins A1 and B, which points to their possible role as biomarkers. Specifically, HDL particles play a protective role in cardiovascular diseases. Using functional human serum cell assays, we observed impaired capacity of apolipoprotein B-depleted serum to induce macrophage cholesterol efflux in severe anaphylactic reactions. In addition, purified HDL particles from human anaphylactic sera failed to stabilize and maintain the endothelial barrier.

CONCLUSION

These results encourage further research on HDL functions in severe anaphylaxis, which may lead to new diagnostic and therapeutic strategies.

Analysis of hyperlipidemia risk factors among pilots based on physical examination data: A study using a multilevel propensity score models

Pilot tends to have a high prevalence of dyslipidemia. The present study aimed to identify key factors of pilot hyperlipidemia through thorough analysis of physical examination data, and to provide pilot-targeted health guidance to manage hyperlipidemia risks. The physical examination data of 1,253 pilot inpatients from January 2019 to June 2022, were evaluated and divided into two groups based on whether or not the pilot had hyperlipidemia. A total of three multivariate analysis models including logistic model, multilevel model and boosting propensity score were applied to find the risk factors of pilot hyperlipidemia. In the group of pilots with hyperlipidemia, four risk factors, including thrombin time, carbohydrate antigen 199, lymphocyte count and rheumatoid factor, were significantly different from pilots without hyperlipidemia, which might be positively associated with the incidence of hyperlipidemia. In future studies regarding pilots, whether hyperlipidemia is connected to abnormalities in thrombin time, carbohydrate antigen 199 and rheumatoid factor should be further explored. Based on the findings of the present study, pilot health management should be more refined and personalized, and attention should be paid to the risk factors of hyperlipidemia including diet and lifestyle.

Association between neutrophil to high-density lipoprotein cholesterol ratio (NHR) and depression symptoms among the United States adults: a cross-sectional study

BACKGROUND

Depression acts as a noteworthy worldwide public health challenge. Identifying accessible biomarkers is crucial for early diagnosis and intervention. The relationship between depression in adult Americans and the neutrophil to high-density lipoprotein cholesterol ratio (NHR) was investigated in this research.

METHODS

The relationship between NHR and depressive symptoms was analyzed utilizing National Health and Nutrition Examination Survey data from 2005 to 2018 and the Patient Health Questionnaire-9. The study included 33,871 participants with complete NHR and depression data. Adjusted multivariable logistic regression models were used to account for possible confounders, and subgroup analyses were conducted to investigate effect changes.

RESULTS

Elevated NHR levels were positively correlated with a heightened risk of depression (OR = 1.03, 95% CI: 1.01-1.05, P < 0.0005). After the NHR was divided into tertiles, those in the top tertile had an 18% higher chance of developing depression than those in the bottom tertile (OR = 1.18; 95% CI: 1.05-1.32; P for trend = 0.0041). Subgroup analyses revealed variations in this association based on race and marital status. Additionally, the relationship between NHR and depression demonstrated a U-shaped pattern, with a significant breakpoint identified at an NHR of 6.97.

CONCLUSION

These results imply that the NHR may be a potential biomarker for depression risk, with implications for early detection and personalized treatment. Further research is needed to elucidate the mechanisms underlying the NHR-depression link and establish causality.

Microbial community-scale metabolic modelling predicts personalized short-chain fatty acid production profiles in the human gut

Microbially derived short-chain fatty acids (SCFAs) in the human gut are tightly coupled to host metabolism, immune regulation and integrity of the intestinal epithelium. However, the production of SCFAs can vary widely between individuals consuming the same diet, with lower levels often associated with disease. A systems-scale mechanistic understanding of this heterogeneity is lacking. Here we use a microbial community-scale metabolic modelling (MCMM) approach to predict individual-specific SCFA production profiles to assess the impact of different dietary, prebiotic and probiotic inputs. We evaluate the quantitative accuracy of our MCMMs using in vitro and ex vivo data, plus published human cohort data. We find that MCMM SCFA predictions are significantly associated with blood-derived clinical chemistries, including cardiometabolic and immunological health markers, across a large human cohort. Finally, we demonstrate how MCMMs can be leveraged to design personalized dietary, prebiotic and probiotic interventions aimed at optimizing SCFA production in the gut. Our model represents an approach to direct gut microbiome engineering for precision health and nutrition.

Association of plasma high-density lipoprotein cholesterol level with risk of stress urinary incontinence in women: a retrospective study

BACKGROUND

Studies have found that high density lipoprotein cholesterol (HDL-C) levels are linked to a variety of diseases. However, evidence for the relationship between stress urinary incontinence (SUI) and HDL-C remain limited.

METHODS

590 eligible women were enrolled. Basic characteristic, gynecological examinations and blood sampling were collected. The examination of the possible link between HDL-C and SUI was done using univariate and multivariate logistic regression. Feature importance ranking and Receiver operating characteristic (ROC) curves were performed to further evaluate the association between HDL-C and SUI in women.

RESULTS

A significant association was found between HDL-C and SUI in women, revealing higher HDL-C levels were related to a lower risk of SUI (OR 0.238; 95%CI: 0.091-0.623; P < 0.01) after adjustment for potential key confounders. The AUC for the SUI predicted by the combined HDL-C was 0.845 (95%CI: 0.798-0.891, P < 0.001). The feature importance ranking revealed that vaginal delivery, HDL-C were the top two important factors.

CONCLUSIONS

HDL-C levels were correlated with the development of SUI. In addition to physical and surgical treatments, HDL-C may offer the possibility of potential targeted treatment and prevention of SUI afterwards.

Effect of IL-6R blockade on plasma lipids and clinical outcomes among hospitalized patients with COVID-19 infection

Plasma lipid levels are modulated by systemic infection and inflammation; it is unknown whether these changes reflect inflammatory responses or caused directly by pathogen presence. We explored the hypothesis that anti-inflammatory intervention via interleukin 6 receptor (IL-6R) blockade would influence plasma lipid levels during severe infection and evaluated the association of plasma lipid changes with clinical outcomes. Sarilumab (monoclonal antibody blocking IL-6R) efficacy was previously assessed in patients with coronavirus disease 2019 (COVID-19) (NCT04315298). This analysis determined whether strong inflammatory reduction by sarilumab in patients with COVID-19 pneumonia of increasing severity (severe, critical, multisystem organ dysfunction) affected plasma lipid changes between day 1 and day 7 of study therapy. Baseline lipid levels reflected the presence of acute systemic infection, characterized by very low HDL-C, low LDL-C, and moderately elevated triglycerides (TGs). Disease severity was associated with progressively more abnormal lipid levels. At day 7, median lipid levels increased more in the sarilumab versus placebo group (HDL-C +10.3%, LDL-C +54.7%, TG +32% vs. HDL-C +1.7%, LDL-C +15.4%, TG +8.8%, respectively). No significant association between lipid changes and clinical outcomes was observed. In conclusion, severe-to-critical COVID-19 pneumonia causes profound HDL-C depression that is only modestly responsive to strong anti-IL-6R inflammatory intervention. Conversely, LDL-C depression is strongly responsive to IL-6R blockade, with LDL-C levels likely returning to the predisease set point. These results advance our understanding of the complex relationship between serum lipids and infection/inflammation and suggest that HDL-C depression during acute contagious disease is driven by infection and not IL-6-mediated inflammation.

High-density lipoprotein mimetic nano-therapeutics targeting monocytes and macrophages for improved cardiovascular care: a comprehensive review

The prevalence of cardiovascular diseases continues to be a challenge for global health, necessitating innovative solutions. The potential of high-density lipoprotein (HDL) mimetic nanotherapeutics in the context of cardiovascular disease and the intricate mechanisms underlying the interactions between monocyte-derived cells and HDL mimetic showing their impact on inflammation, cellular lipid metabolism, and the progression of atherosclerotic plaque. Preclinical studies have demonstrated that HDL mimetic nanotherapeutics can regulate monocyte recruitment and macrophage polarization towards an anti-inflammatory phenotype, suggesting their potential to impede the progression of atherosclerosis. The challenges and opportunities associated with the clinical application of HDL mimetic nanotherapeutics, emphasize the need for additional research to gain a better understanding of the precise molecular pathways and long-term effects of these nanotherapeutics on monocytes and macrophages to maximize their therapeutic efficacy. Furthermore, the use of nanotechnology in the treatment of cardiovascular diseases highlights the potential of nanoparticles for targeted treatments. Moreover, the concept of theranostics combines therapy and diagnosis to create a selective platform for the conversion of traditional therapeutic medications into specialized and customized treatments. The multifaceted contributions of HDL to cardiovascular and metabolic health via highlight its potential to improve plaque stability and avert atherosclerosis-related problems. There is a need for further research to maximize the therapeutic efficacy of HDL mimetic nanotherapeutics and to develop targeted treatment approaches to prevent atherosclerosis. This review provides a comprehensive overview of the potential of nanotherapeutics in the treatment of cardiovascular diseases, emphasizing the need for innovative solutions to address the challenges posed by cardiovascular diseases.

Association between Mycoplasma pneumoniae infection, high‑density lipoprotein metabolism and cardiovascular health (Review)

The association between Mycoplasma pneumoniae (M. pneumoniae) infection, high-density lipoprotein metabolism and cardiovascular disease is an emerging research area. The present review summarizes the basic characteristics of M. pneumoniae infection and its association with high-density lipoprotein and cardiovascular health. M. pneumoniae primarily invades the respiratory tract and damages the cardiovascular system through various mechanisms including adhesion, invasion, secretion of metabolites, production of autoantibodies and stimulation of cytokine production. Additionally, the present review highlights the potential role of high-density lipoprotein for the development of prevention and intervention of M. pneumoniae infection and cardiovascular disease, and provides suggestions for future research directions and clinical practice. It is urgent to explore the specific mechanisms underlying the association between M. pneumoniae infection, high-density lipoprotein metabolism, and cardiovascular disease and analyze the roles of the immune system and inflammatory response.

LOW HIGH-DENSITY LIPOPROTEIN LEVEL ASSOCIATED WITH ENHANCED INFLAMMATORY RESPONSE AND ONE-YEAR PERSISTENCE OF LONG COVID IN PATIENTS UNDERGOING HEMODIALYSIS: A CROSS-SECTIONAL COHORT STUDY

Background: Long-term consequences of COVID-19, known as long COVID, present distinctive hurdles for patients receiving hemodialysis treatment. Reduced levels of high-density lipoprotein (HDL) (< 1.22 mmol/L) have previously been demonstrated to be associated with heightened susceptibility to COVID-19 and immediate COVID-19-related adverse outcomes in this patient population. However, the potential association between HDL levels and the persistence of long COVID has not been examined within the hemodialysis cohort. The present study aimed to explore the relationship between HDL levels and inflammatory responses one year after COVID-19 among patients undergoing hemodialysis. Methods: A total of 80 patients treated with hemodialysis, aged 55 (44-62.5) years, with a dialysis vintage of 45 (21-78.6) months and a history of COVID-19, were enrolled in this cross-sectional cohort study. Among them, 45 (56.2%) were diagnosed with long COVID, while 35 (43.8%) had fully recovered. Lipid profiles and inflammatory markers, such as serum C-reactive protein, and interleukins -6 and -17, were assessed one year post-infection. Results: Patients experiencing long COVID exhibited significantly lower HDL levels compared to fully recovered individuals: 1.19 (1.06-1.76) vs 1.66 (1.32-1.92) mmol/L (p < 0.0001). The HDL cut-off point of less than 1.22 mmol/L demonstrated a sensitivity of 84.9% and specificity of 95.3% to predict one-year long COVID persistence in our cohort. Among the patients with HDL levels < 1.22 mmol/L, elevated concentrations of C-reactive protein (р = 0.003), interleukin-6 (p = 0.005), and interleukin-17 (p < 0.0001) were evident compared to those with HDL concentrations exceeding 1.22 mmol/L. Subsequent subgroup analysis revealed a more pronounced inflammatory profile in patients concurrently experiencing long COVID and exhibiting low HDL levels. Conclusion: The obtained results suggest that a low level of HDL (< 1.22 mmol/L) may exacerbate the inflammatory response in patients undergoing hemodialysis, potentially contributing to the persistence of long COVID even a year after infection. Future research is necessary to elucidate the pathogenetic mechanisms of this relationship and explore potential strategies to improve patient outcomes.

Associations between circulating cardiovascular disease risk factors and cognitive performance in cognitively healthy older adults from the NuAge study

Introduction

Cardiovascular disease risk factors (CVRFs) contribute to the development of cognitive impairment and dementia.

Methods

This study examined the associations between circulating CVRF biomarkers and cognition in 386 cognitively healthy older adults (mean age = 78 ± 4 years, 53% females) selected from the Quebec Longitudinal Study on Nutrition and Successful Aging (NuAge). Memory, executive function, and processing speed were assessed at baseline and 2-year follow-up. CVRF biomarkers included total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglycerides, glucose, insulin, high sensitivity C-reactive protein (hs-CRP), homocysteine, protein carbonyls, and cortisol. Linear mixed models were used to determine associations between individual CVRF biomarkers and cognition at both time points.

Results

HDL-C was most consistently associated with cognition with higher values related to better performance across several domains. Overall, stronger and more consistent relationships between CVRF biomarkers and cognition were observed in females relative to males.

Discussion

Findings suggest that increases in the majority of circulating CVRFs are not associated with worse cognition in cognitively healthy older adults.

HDL anti-inflammatory function is impaired and associated with high SAA1 and low APOA4 levels in aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating disease with high morbidity and mortality rates. Within 24 hours after aSAH, monocytes are recruited and enter the subarachnoid space, where they mature into macrophages, increasing the inflammatory response and contributing, along with other factors, to delayed neurological dysfunction and poor outcomes. High-density lipoproteins (HDL) are lipid-protein complexes that exert anti-inflammatory effects but under pathological conditions undergo structural alterations that have been associated with loss of functionality. Plasma HDL were isolated from patients with aSAH and analyzed for their anti-inflammatory activity and protein composition. HDL isolated from patients lost the ability to prevent VCAM-1 expression in endothelial cells (HUVEC) and subsequent adhesion of THP-1 monocytes to the endothelium. Proteomic analysis showed that HDL particles from patients had an altered composition compared to those of healthy subjects. We confirmed by western blot that low levels of apolipoprotein A4 (APOA4) and high of serum amyloid A1 (SAA1) in HDL were associated with the lack of anti-inflammatory function observed in aSAH. Our results indicate that the study of HDL in the pathophysiology of aSAH is needed, and functional HDL supplementation could be considered a novel therapeutic approach to the treatment of the inflammatory response after aSAH.

Associations between neighborhood socioeconomic deprivation, IFNγ, and high-density lipoprotein particle size: Data from the Washington, D.C. cardiovascular health and needs assessment

INTRODUCTION

Neighborhood socioeconomic deprivation is associated with increased cardiovascular risk factors, including inflammation. Inflammation plays an important role in modifying the cardioprotective function of high-density lipoprotein (HDL). Moreover, recent studies suggest that very high HDL is associated with adverse cardiovascular disease (CVD) outcomes. Thus, we sought to explore the relationships between neighborhood socioeconomic deprivation as a marker of chronic stress, inflammation, proprotein convertase subtilisin/kexin type 9 (PCSK9) (a core component of the HDL proteome), HDL characterisitcs, and biological aging as a predictor of CVD and all-cause mortality.

METHODS

Sixty African American subjects were recruited to the NIH Clinical Center as part of a community-based participatory research-designed observational study. Neighborhood deprivation index (NDI), a marker of neighborhood socioeconomic deprivation, was measured using US Census data. HDL characteristics (cholesterol, particle number, size, subspecies) were determined from NMR lipoprotein profiling, and plasma cytokines (IL-1β, IL-6, IL-8, TNFα, IFNγ) were measured using an ELISA-based multiplex technique. Epigenetic clock biomarkers of aging were measured using DNA methylation data obtained from participants' buffy coat samples. We used linear regression modeling adjusted for atherosclerotic cardiovascular disease (ASCVD) risk score, body mass index (BMI), and lipid-lowering medication use to investigate relationships of interest.

RESULTS

NDI directly associated with large HDL particle count (H7P) and IFNγ and trended toward significance with HDL-C and PCSK9. IFNγ and PCSK9 then directly associated with H7P. H7P also directly associated with higher DNA methylation phenotypic age (PhenoAge).

CONCLUSION

We highlight associations between neighborhood socioeconomic deprivation, IFNγ, PCSK9, HDL subspecies, and epigenetic biomarkers of aging. Taken together, our findings suggest indirect pathways linking neighborhood deprivation-related stress and inflammation to HDL and immune epigenetic changes. Moreover, these results add to recent work showing the pathogenicity of high HDL levels and underscore the need to understand how chronic stress-related inflammation and lipoprotein subspecies relate to CVD risk across diverse populations.

Dysfunctional high-density lipoprotein in chronic inflammatory rheumatic diseases

Background

The mechanism explaining low cholesterol concentrations in chronic inflammatory rheumatic disease (CIRD) is incompletely understood. We hypothesized that chronic inflammation impairs the functionality of high-density lipoprotein (HDL), for example, by oxidative processes.

Objectives

Assessment of oxidized HDL (HDLox), a marker of dysfunctional HDL, in newly diagnosed patients with CIRD before and after initiation of immunosuppressive therapy and comparison of HDLox values of patients with CIRD to non-CIRD controls.

Design

Prospective observational trial.

Methods

The study was conducted on 44 newly diagnosed CIRD patients, who were initiated on immunosuppressive therapy (baseline). A total of 136 patients without CIRD served as control. Lipid profiles including HDLox levels and C-reactive protein (CRP) were measured in both groups at baseline. In CIRD patients, measurements were repeated 12 weeks after baseline. Validated outcome tools for disease activity and function were assessed at baseline and 12 weeks.

Results

A total of 33 (75%) patients with rheumatoid arthritis, 7(16%) with axial spondyloarthritis, and 4 (9%) with systemic lupus erythematosus were included. Groups were comparable for age and BMI. CIRD patients had higher HDLox concentrations (1.57 versus 0.78, p = 0.02) and tended to have lower low-density lipoprotein cholesterol, HDL cholesterol, and cholesterol concentrations compared to controls. HDLox (1.57 versus 1.4, p = 0.26) and CRP levels (2.1 versus 0.7 mg/dl, p < 0.01) decreased in CIRD patients from baseline to follow-up.

Conclusion

CIRD is associated with an impairment of the anti-inflammatory properties of HDL as reflected by an increase in HDLox concentrations. This effect may contribute to the increased cardiovascular risk in chronic inflammatory diseases.

Changes in Metabolic Health and Sedentary Behavior in Obese Children and Adolescents

Obesity is becoming more common among children and adolescents. As in adults, obesity in the pediatric population is associated with an increased risk of metabolic disorders and diseases. In the related literature, little attention has been devoted to evaluating how metabolic health and sedentary behavior change in the obese pediatric population. Therefore, this study aimed to assess changes in metabolic health and sedentary behavior in obese children aged 7-12 and adolescents aged 13-17. For this single-center hospital-based prospective observational study, we included 202 Polish children and adolescents aged 7-17 years. We performed blood pressure measurements and collected blood samples to assess metabolic health markers. Based on the performed measurements, we also calculated additional indexes and ratios: BMI, WHtR, ABSI, VAI, and HOMA-IR. The analysis of the results showed clear and significant differences between the study groups. The older boys and girls were identified with higher values of anthropometric ratios, blood pressure, time spent sitting, and lower HDL cholesterol values (p < 0.05). The analysis also revealed a strong-to-moderate correlation between age and anthropometric ratios, blood pressure, HDL cholesterol, and sitting time (p < 0.05). Obese children and adolescents included in this study represent poor metabolic health and are at great risk of developing other metabolic diseases such as type 2 diabetes, hypertension, or metabolic syndrome. This risk increases with age; therefore, a number of preventive and therapeutic actions should be taken in overweight and obese children and adolescents to avoid further metabolic complications.

Associations between serum cholesterol and immuno-phenotypical characteristics of circulatory B cells and Tregs

Blood lipids play a major role in the manifestation of cardiovascular diseases. Recent research suggested that there are connections between cholesterol levels and immunological alterations. We investigated whether there is an association between serum cholesterol levels (total, HDL, LDL) and immune cells (B cell and regulatory T cells [Tregs]). The analysis was based on data from 231 participants of the MEGA study in Augsburg, Germany, recruited between 2018 and 2021. Most participants was examined two different times within a time period of 9 months. At every visit, fasting venous blood samples were taken. Immune cells were analyzed immediately afterwards using flow cytometry. Using multivariable-adjusted linear regression models, the associations between blood cholesterol concentrations and the relative quantity of several B cell and Treg subsets were analyzed. We found that particularly HDL cholesterol concentrations were significantly associated to some immune cell subpopulations: HDL cholesterol showed significant positive associations with the relative frequency of CD25++ Tregs (as proportion of all CD4+CD25++ T cells) and conventional Tregs (defined as the proportion of CD25+CD127- cells on all CD45RA- CD4+ T cells). Regarding B cells, HDL cholesterol values were inversely associated with the cell surface expression of IgD and with naïve B cells (CD27- IgD+ B cells). In conclusion, HDL cholesterol levels were associated with modifications in the composition of B cell and Tregs subsets demonstrating an important interconnection between lipid metabolism and immune system. Knowing that this association exists might be crucial for a deeper and more comprehensive understanding of the pathophysiology of atherosclerosis.

Anti-Inflammatory Effects of Allocryptopine via the Target on the CX3CL1-CX3CR1 axis/GNB5/AKT/NF-κB/Apoptosis in Dextran Sulfate-Induced Mice

Allocryptopine (ALL) is an isoquinoline alkaloid extracted from Macleaya cordata(Willd). R. Br., which has been claimed to have anti-inflammatory and neuroprotection properties. However, the mechanism by which ALL ameliorates inflammatory bowel disease (IBD) remains unclear. Here, we used network pharmacology and quantitative proteomic approaches to investigate the effect of ALL on IBD pathogenesis. Network pharmacology predicted potential targets and signaling pathways of ALL's anti-IBD effects. As predicted by network pharmacology, gene ontology (GO) analysis, in terms of the proteomic results, showed that the immune response in mucosa and antimicrobial humoral response were enriched. Further study revealed that the ALL-related pathways were the chemokine signaling pathway and apoptosis in the Kyoto Encyclopedia of Genes and Genomes (KEGG). In addition, we identified AKT1 as a hub for the critical pathways through protein-protein interaction (PPI) network analysis. Similar to mesalazine (MES), Western blot verified that ALL downregulated upstream chemokine CX3CL1 and GNB5 content to reduce phosphorylation of AKT and NF-κB, as well as the degree of apoptosis, to improve inflammatory response in the colon. Our research may shed light on the mechanism by which ALL inhibits the CX3CL1/GNB5/AKT2/NF-κB/apoptosis pathway and improves the intestinal barrier to reduce colitis response and act on the CX3CL1-CX3CR1 axis to achieve neuroprotection.

Serum LDL-C/HDL-C ratio and the risk of carotid plaques: a longitudinal study

BACKGROUND

Dyslipidemia contributes to an increased risk of carotid atherosclerosis. However, the association between the ratio of low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol (HDL-C) and carotid plaque formation has not been well documented. This study aims to assess the role of LDL-C/HDL-C in the risk of carotid plaque formation in a Chinese population.

METHODS

We followed 2,191 participants who attended the annual routine health examination. Cox proportional hazards regression, restricted cubic spline (RCS), and subgroup analysis were applied to evaluate the association between the LDL-C/HDL-C ratio and carotid plaques. The hazard ratio (HR) and 95% confidence interval (CI) were used to estimate the strength of the association.

RESULTS

Among 2,191 participants, 388 had incident carotid plaques detected, with a median follow-up time of 1.05 years. Compared with subjects younger than 45 years, those aged 45 to 59 years (HR: 2.00, 95% CI: 1.55-2.58) and over 60 years (HR: 3.36, 95% CI: 2.47-4.58) had an increased risk of carotid plaque formation. Males (HR: 1.26, 95% CI: 1.01-1.56), diabetes (HR: 1.46, 95% CI: 1.06-2.01) and a high LDL-C/HDL-C ratio (HR: 1.22, 95% CI: 1.07-1.38) were significantly linked with the occurrence of carotid plaques. After adjusting for potential confounding factors, we observed that a high LDL-C/HDL-C ratio promoted carotid plaque events (HR: 1.30, 95% CI: 1.12-1.50). The RCS analysis revealed a significant nonlinear association. The association was stronger among females (P-interaction < 0.05).

CONCLUSION

A high LDL-C/HDL-C ratio could accelerate the occurrence of carotid plaques. Older men with diabetes and dyslipidemia are the critical target population. Women may be more likely to benefit from lipid-lowering interventions and thus avoid carotid plaque formation.

High-density lipoprotein revisited: biological functions and clinical relevance

Previous interest in high-density lipoproteins (HDLs) focused on their possible protective role in atherosclerotic cardiovascular disease (ASCVD). Evidence from genetic studies and randomized trials, however, questioned that the inverse association of HDL-cholesterol (HDL-C) is causal. This review aims to provide an update on the role of HDL in health and disease, also beyond ASCVD. Through evolution from invertebrates, HDLs are the principal lipoproteins, while apolipoprotein B-containing lipoproteins first developed in vertebrates. HDLs transport cholesterol and other lipids between different cells like a reusable ferry, but serve many other functions including communication with cells and the inactivation of biohazards like bacterial lipopolysaccharides. These functions are exerted by entire HDL particles or distinct proteins or lipids carried by HDL rather than by its cholesterol cargo measured as HDL-C. Neither does HDL-C measurement reflect the efficiency of reverse cholesterol transport. Recent studies indicate that functional measures of HDL, notably cholesterol efflux capacity, numbers of HDL particles, or distinct HDL proteins are better predictors of ASCVD events than HDL-C. Low HDL-C levels are related observationally, but also genetically, to increased risks of infectious diseases, death during sepsis, diabetes mellitus, and chronic kidney disease. Additional, but only observational, data indicate associations of low HDL-C with various autoimmune diseases, and cancers, as well as all-cause mortality. Conversely, extremely high HDL-C levels are associated with an increased risk of age-related macular degeneration (also genetically), infectious disease, and all-cause mortality. HDL encompasses dynamic multimolecular and multifunctional lipoproteins that likely emerged during evolution to serve several physiological roles and prevent or heal pathologies beyond ASCVD. For any clinical exploitation of HDL, the indirect marker HDL-C must be replaced by direct biomarkers reflecting the causal role of HDL in the respective disease.

Lack of ApoA-I in ApoEKO Mice Causes Skin Xanthomas, Worsening of Inflammation, and Increased Coronary Atherosclerosis in the Absence of Hyperlipidemia

Background:

HDL (high-density lipoprotein) and its major protein component, apoA-I (apolipoprotein A-I), play a unique role in cholesterol homeostasis and immunity. ApoA-I deficiency in hyperlipidemic, atheroprone mice was shown to drive cholesterol accumulation and inflammatory cell activation/proliferation. The present study was aimed at investigating the impact of apoA-I deficiency on lipid deposition and local/systemic inflammation in normolipidemic conditions.

Methods:

ApoE deficient mice, apoE/apoA-I double deficient (DKO) mice, DKO mice overexpressing human apoA-I, and C57Bl/6J control mice were fed normal laboratory diet until 30 weeks of age. Plasma lipids were quantified, atherosclerosis development at the aortic sinus and coronary arteries was measured, skin ultrastructure was evaluated by electron microscopy. Blood and lymphoid organs were characterized through histological, immunocytofluorimetric, and whole transcriptome analyses.

Results:

DKO were characterized by almost complete HDL deficiency and by plasma total cholesterol levels comparable to control mice. Only DKO showed xanthoma formation and severe inflammation in the skin-draining lymph nodes, whose transcriptome analysis revealed a dramatic impairment in energy metabolism and fatty acid oxidation pathways. An increased presence of CD4⁺ T effector memory cells was detected in blood, spleen, and skin-draining lymph nodes of DKO. A worsening of atherosclerosis at the aortic sinus and coronary arteries was also observed in DKO versus apoE deficient. Human apoA-I overexpression in the DKO background was able to rescue the skin phenotype and halt atherosclerosis development.

Conclusions:

HDL deficiency, in the absence of hyperlipidemia, is associated with severe alterations of skin morphology, aortic and coronary atherosclerosis, local and systemic inflammation.

HDL functionality in type 1 and type 2 diabetes: new insights

PURPOSE OF REVIEW

To critically appraise new insights into HDL structure and function in type 1 diabetes (T1DM) and type 2 diabetes (T2DM).

RECENT FINDINGS

In young T1DM patients with early renal impairment and a high inflammatory score, both HDL antioxidative activity and endothelial vasodilatory function were impaired, revealing a critical link between HDL dysfunction, subclinical vascular damage, systemic inflammation and end organ damage. HDL may inhibit development of T2DM by attenuating endoplasmic reticulum (ER) stress and apoptotic loss of pancreatic β-cells, an effect due in part to ABC transporter-mediated efflux of specific oxysterols with downstream activation of the hedghehog signalling receptor, Smoothened. The apoM-sphingosine-1-phosphate complex is critical to HDL antidiabetic activity, encompassing protection against insulin resistance, promotion of insulin secretion, enhanced β-cell survival and inhibition of hepatic glucose production. Structure-function studies of HDL in hyperglycemic, dyslipidemic T2DM patients revealed both gain and loss of lipidomic and proteomic components. Such changes attenuated both the optimal protective effects of HDL on mitochondrial function and its capacity to inhibit endothelial cell apoptosis. Distinct structural components associated with individual HDL functions.

SUMMARY

Extensive evidence indicates that both the proteome and lipidome of HDL are altered in T1DM and T2DM, with impairment of multiple functions.

Understanding Myeloperoxidase-Induced Damage to HDL Structure and Function in the Vessel Wall: Implications for HDL-Based Therapies

Atherosclerosis is a disease of increased oxidative stress characterized by protein and lipid modifications in the vessel wall. One important oxidative pathway involves reactive intermediates generated by myeloperoxidase (MPO), an enzyme present mainly in neutrophils and monocytes. Tandem MS analysis identified MPO as a component of lesion derived high-density lipoprotein (HDL), showing that the two interact in the arterial wall. MPO modifies apolipoprotein A1 (apoA-I), paraoxonase 1 and certain HDL-associated phospholipids in human atheroma. HDL isolated from atherosclerotic plaques depicts extensive MPO mediated posttranslational modifications, including oxidation of tryptophan, tyrosine and methionine residues, and carbamylation of lysine residues. In addition, HDL associated plasmalogens are targeted by MPO, generating 2-chlorohexadecanal, a pro-inflammatory and endothelial barrier disrupting lipid that suppresses endothelial nitric oxide formation. Lesion derived HDL is predominantly lipid-depleted and cross-linked and exhibits a nearly 90% reduction in lecithin-cholesterol acyltransferase activity and cholesterol efflux capacity. Here we provide a current update of the pathophysiological consequences of MPO-induced changes in the structure and function of HDL and discuss possible therapeutic implications and options. Preclinical studies with a fully functional apoA-I variant with pronounced resistance to oxidative inactivation by MPO-generated oxidants are currently ongoing. Understanding the relationships between pathophysiological processes that affect the molecular composition and function of HDL and associated diseases is central to the future use of HDL in diagnostics, therapy, and ultimately disease management.

HDL and reverse cholesterol transport in humans and animals: Lessons from pre-clinical models and clinical studies

The ability to accept cholesterol from cells and to promote reverse cholesterol transport (RCT) represents the best characterized antiatherogenic function of HDL. Studies carried out in animal models have unraveled the multiple mechanisms by which these lipoproteins drive cholesterol efflux from macrophages and cholesterol uptake to the liver. Moreover, the influence of HDL composition and the role of lipid transporters have been clarified by using suitable transgenic models or through experimental design employing pharmacological or nutritional interventions. Cholesterol efflux capacity (CEC), an in vitro assay developed to offer a measure of the first step of RCT, has been shown to associate with cardiovascular risk in several human cohorts, supporting the atheroprotective role of RCT in humans as well. However, negative data in other cohorts have raised concerns on the validity of this biomarker. In this review we will present the most relevant data documenting the role of HDL in RCT, as assessed in classical or innovative methodological approaches.

HDL and persistent inflammation immunosuppression and catabolism syndrome

PURPOSE OF REVIEW

This study reviews the mechanisms of HDL cholesterol immunomodulation in the context of the mechanisms of chronic inflammation and immunosuppression causing persistent inflammation, immunosuppression and catabolism syndrome (PICS) and describes potential therapies and gaps in current research.

RECENT FINDINGS

Low HDL cholesterol is predictive of acute sepsis severity and outcome. Recent research has indicated apolipoprotein is a prognostic indicator of long-term outcomes. The pathobiologic mechanisms of PICS have been elucidated in the past several years. Recent research of the interaction of HDL pathways in related chronic inflammatory diseases may provide insights into further mechanisms and therapeutic targets.

SUMMARY

HDL significantly influences innate and adaptive immune pathways relating to chronic disease and inflammation. Further research is needed to better characterize these interactions in the setting of PICS.

Lipids and Lipoproteins in Health and Disease: Focus on Targeting Atherosclerosis

Despite advances in pharmacotherapy, intervention devices and techniques, residual cardiovascular risks still cause a large burden on public health. Whilst most guidelines encourage achieving target levels of specific lipids and lipoproteins to reduce these risks, increasing evidence has shown that molecular modification of these lipoproteins also has a critical impact on their atherogenicity. Modification of low-density lipoprotein (LDL) by oxidation, glycation, peroxidation, apolipoprotein C-III adhesion, and the small dense subtype largely augment its atherogenicity. Post-translational modification by oxidation, carbamylation, glycation, and imbalance of molecular components can reduce the capacity of high-density lipoprotein (HDL) for reverse cholesterol transport. Elevated levels of triglycerides (TGs), apolipoprotein C-III and lipoprotein(a), and a decreased level of apolipoprotein A-I are closely associated with atherosclerotic cardiovascular disease. Pharmacotherapies aimed at reducing TGs, lipoprotein(a), and apolipoprotein C-III, and enhancing apolipoprotein A-1 are undergoing trials, and promising preliminary results have been reported. In this review, we aim to update the evidence on modifications of major lipid and lipoprotein components, including LDL, HDL, TG, apolipoprotein, and lipoprotein(a). We also discuss examples of translating findings from basic research to potential therapeutic targets for drug development.