The distinct metabolism between large and small HDL indicates unique origins of human apolipoprotein A4

Potential of CETP inhibition in treating dyslipidemia in systemic lupus erythematosus: Novel and comprehensive evidence from clinical studies and Mendelian randomization

OBJECTIVE

Cardiovascular diseases from abnormal lipid metabolism significantly increase mortality in systemic lupus erythematosus (SLE). The causal link between dyslipidemia and SLE is unclear.

METHODS

Lipid metabolism in patients with SLE was evaluated based on clinical data from 511 patients with SLE and 706 healthy individuals. Bidirectional Mendelian randomization (MR) was employed to assess causal links between 179 plasma lipid metabolites, lipid-lowering drug targets, and SLE risk. Genetic instruments from GWAS and eQTL data were used to evaluate CETP and APOA4 effects. Peripheral blood CETP and apolipoprotein levels in SLE patients were validated via ELISA.

RESULTS

SLE patients exhibited reduced HDL-C (P < 0.0001), APOA1 (P < 0.0001), and APOA4 (P < 0.0001), alongside elevated triglycerides (TG, P < 0.0001), APOC3, APOD, and APOF. MR identified three lipid metabolites-PC(18:2_20:4), TG(56:6), and TG(58:7)-as causal factors for SLE (P < 2.79E-5). CETP inhibition significantly reduced SLE risk via HDL-C modulation (OR = 0.72, P = 3.38E-08) and influenced LDL-C, TG, and apolipoproteins. Clinical validation confirmed elevated CETP and reduced APOA4 in SLE, correlating with disease activity. APOA4 activation showed protective effects, while PCSK9 inhibition lacked relevance.

CONCLUSION

Bidirectional Mendelian randomization analyses confirmed dyslipidemia as a causal antecedent to SLE, with no evidence of reverse causation. A variety of MR analyses and clinical validation indicated that targeting HDL-C regulation offers significant advantages for managing dyslipidemia in patients with SLE, with CETP identified as the optimal pharmacological target.

Advances in Apolipoprotein-A4 Biosensing Assays for Depression Diagnosis

Apolipoprotein-A4 (Apo-A4) is a plasma protein that plays a role in various physiological and behavioral-emotional reactions when faced with stress. Studies have shown a close relationship between Apo-A4 and the onset of depression and its symptoms. However, there is currently no reliable laboratory approach to confirm the diagnosis of depression. Therefore, the development of a precise and effective technique to assess Apo-A4 might help in the early detection and screening of depression and other related psychiatric diseases, as well as in tracking and managing the course of treatment. As technology advances, biosensors have become quick, accurate, and sensitive tools for personal care and illness diagnosis. Biosensors for measuring and detecting Apo-A4 levels have recently been designed. These studies emphasized the development of accurate and sensitive diagnostic and measurement techniques. This review attempts to give a general overview of the role of Apo-A4 in depression and introduce established biosensors for its detection and measurement.

High-fat diet alters retinal lipid composition and gene expression networks in mice

BACKGROUND

High-fat diet (HFD) was suggested to be associated with several retinal diseases, including age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR). Nevertheless, our understanding of the mechanisms governing retinal lipid metabolic homeostasis remains limited, with little attention focused on the influence of HFD on different retinal cell types. To address this gap, we established a high-fat model using mice fed with HFD for a duration of 6 months. Then, we conducted a comparative analysis of the retinal lipidome and proteome between normal diet (ND) and HFD-fed mice to explore the impacts of HFD on retinal lipid metabolism and gene expression network. Furthermore, we also investigated the impacts of HFD on retina in single-cell resolution by single-cell transcriptome sequencing.

RESULTS

We found that a long-term HFD significantly altered the lipid composition of the retina, with a dramatically elevated cholesterylesters (CE), phosphatidylcholine (PC), and phosphatidylglycerol (PG) level and a decreased eicosanoid level. Proteomic analysis revealed that the primary bile acid biosynthesis pathway was over-activated in HFD retinas. By using single-cell transcriptome analysis, we identified different regulation of gene expression in MG and rod cells in a high-fat environment, whereas the previously identified activation of the bile acid synthesis pathway was predominantly found in MG cells, and may be regulated by alternative pathways of bile acid synthesis, suggesting the critical roles of MG cells in retinal lipid metabolism.

CONCLUSIONS

Taken together, by multi-omics studies, we unveiled that HFD leading to the development of retinal diseases may be regulated by alternative pathways of bile acid synthesis, and our study will shed light on the treatment of these diseases.

A genotype-phenotype transformer to assess and explain polygenic risk

Genome-wide association studies have linked millions of genetic variants to biomedical phenotypes, but their utility has been limited by lack of mechanistic understanding and widespread epistatic interactions. Recently, Transformer models have emerged as a powerful machine learning architecture with potential to address these and other challenges. Accordingly, here we introduce the Genotype-to-Phenotype Transformer (G2PT), a framework for modeling hierarchical information flow among variants, genes, multigenic systems, and phenotypes. As proof-of-concept, we use G2PT to model the genetics of TG/HDL (triglycerides to high-density lipoprotein cholesterol), an indicator of metabolic health. G2PT predicts this trait via attention to 1,395 variants underlying at least 20 systems, including immune response and cholesterol transport, with accuracy exceeding state-of-the-art. It implicates 40 epistatic interactions, including epistasis between APOA4 and CETP in phospholipid transfer, a target pathway for cholesterol modification. This work positions hierarchical graph transformers as a next-generation approach to polygenic risk.

Activating transcription factor 3 regulates hepatic apolipoprotein A4 upon metabolic stress

The liver plays essential roles in maintaining systemic glucolipid homeostasis under ever changing metabolic stressors. Metabolic dysregulation can lead to both adaptive and maladaptive changes that impact systemic physiology. Here, we examined disparate genetic and environmental metabolic stressors and identified apolipoprotein A4 (ApoA4) as a circulating protein upregulated in liver-specific KOs for carnitine palmitoyltransferase 2 and pyruvate carboxylase. We found this upregulation to be exacerbated by fasting and high-fat or ketogenic diets. Unique among these models was a concomitant increase in activating transcription factor 3 (Atf3). Liver-specific overexpression of Atf3 resulted in increased ApoA4 expression in a sex-dependent manner. To understand the requirement of Atf3 to metabolic stress, we generated liver-specific Atf3, Cpt2 double KO mice. These experiments demonstrated the requirement for Atf3 in the induction of ApoA4 mRNA, ApoA4 protein, and serum triglycerides that were also sex-dependent. These experiments reveal the roles of hepatic Atf3 and ApoA4 in response to metabolic stress in vivo.

Uncovering the health implications of abandoned mines through protein profiling of local residents

Residents in areas with abandoned mines risk significant exposure to abundant heavy metals in the environment. However, current clinical indicators cannot fully reflect the health changes associated with abandoned mine exposure. The aim of this study was to identify biological changes in the residents of abandoned mine areas via proteomic analysis of their blood. Blood samples were collected from abandoned mine and control areas, and mass spectrometry was used for protein profiling. A total of 138 unique or common proteins that were differentially expressed in low-exposure abandoned mine area (LoAMA) or high-exposure abandoned mine area (HiAMA) compared to non-exposure control area (NEA) were analyzed, and identified 4 clusters based on functional similarity. Among the 10 proteins that showed specific change in LoAMA, 4 proteins(Apolipoprotein M, Apolipoprotein E, Apolipoprotein L1, and Cholesteryl ester transfer protein) were cluded in cluster 1(plasma lipoprotein remodeling), and linked to proteins that showed specific change in protein expression in HiAMA. Therefore, it is suggested that 4 proteins are changed at low exposure to an abandoned mine (or initial exposure), and then at high exposure, changes in various proteins involved in linked plasma lipoprotein remodeling are induced, which might triggered by the 4 proteins. Interestingly, in addition to plasma lipoprotein remodeling, proteins involved in other functional networks were changed in the high exposure group. These were all directly or indirectly linked to the 4 biomarkers(Apolipoprotein M, Apolipoprotein E, Apolipoprotein L1, and Cholesteryl ester transfer protein) that changed during low exposure. This suggests their potential utility in identifying areas impacted by abandoned mines. Especially, proteins involved in lipid metabolism and renal function-related diseases in individuals exposed to heavy metals in abandoned mine areas were correlated. Chronic kidney disease is predominantly instigated by cardiovascular disease and is commonly accompanied by dyslipidemia.

Elevated lipopolysaccharide binding protein in Alzheimer's disease patients with APOE3/E3 but not APOE3/E4 genotype

Introduction

The role of lipopolysaccharide binding protein (LBP), an inflammation marker of bacterial translocation from the gastrointestinal tract, in Alzheimer's disease (AD) is not clearly understood.

Methods

In this study the concentrations of LBP were measured in n = 79 individuals: 20 apolipoprotein E (APOE)3/E3 carriers with and 20 without AD dementia, and 19 APOE3/E4 carriers with and 20 without AD dementia. LBP was found to be enriched in the 1.21-1.25 g/mL density fraction of plasma, which has previously been shown to be enriched in intestinally derived high-density lipoproteins (HDL). LBP concentrations were measured by ELISA.

Results

LBP was significantly increased within the 1.21-1.25 g/mL density fraction of plasma in APOE3/E3 AD patients compared to controls, but not APOE3/E4 patients. LBP was positively correlated with Clinical Dementia Rating (CDR) and exhibited an inverse relationship with Verbal Memory Score (VMS).

Discussion

These results underscore the potential contribution of gut permeability to bacterial toxins, measured as LBP, as an inflammatory mediator in the development of AD, particularly in individuals with the APOE3/E3 genotype, who are genetically at 4-12-fold lower risk of AD than individuals who express APOE4.

Understanding HDL Metabolism and Biology Through In Vivo Tracer Kinetics

HDL (high-density lipoprotein), owing to its high protein content and small size, is the densest circulating lipoprotein. In contrast to lipid-laden VLDL (very-low-density lipoprotein) and LDL (low-density lipoprotein) that promote atherosclerosis, HDL is hypothesized to mitigate atherosclerosis via reverse cholesterol transport, a process that entails the uptake and clearance of excess cholesterol from peripheral tissues. This process is mediated by APOA1 (apolipoprotein A-I), the primary structural protein of HDL, as well as by the activities of additional HDL proteins. Tracer-dependent kinetic studies are an invaluable tool to study HDL-mediated reverse cholesterol transport and overall HDL metabolism in humans when a cardiovascular disease therapy is investigated. Unfortunately, HDL cholesterol-raising therapies have not been successful at reducing cardiovascular events suggesting an incomplete picture of HDL biology. However, as HDL tracer studies have evolved from radioactive isotope- to stable isotope-based strategies that in turn are reliant on mass spectrometry technologies, the complexity of the HDL proteome and its metabolism can be more readily addressed. In this review, we outline the motivations, timelines, advantages, and disadvantages of the various tracer kinetics strategies. We also feature the metabolic properties of select HDL proteins known to regulate reverse cholesterol transport, which in turn underscore that HDL lipoproteins comprise a heterogeneous particle population whose distinct protein constituents and kinetics likely determine its function and potential contribution to cholesterol clearance.

Precision Nutrition and Cardiovascular Disease Risk Reduction: the Promise of High-Density Lipoproteins

PURPOSE OF REVIEW

Emerging evidence supports the promise of precision nutritional approaches for cardiovascular disease (CVD) prevention. Here, we discuss current findings from precision nutrition trials and studies reporting substantial inter-individual variability in responses to diets and dietary components relevant to CVD outcomes. We highlight examples where early precision nutrition research already points to actionable intervention targets tailored to an individual's biology and lifestyle. Finally, we make the case for high-density lipoproteins (HDL) as a compelling next generation target for precision nutrition aimed at CVD prevention. HDL possesses complex structural features including diverse protein components, lipids, size distribution, extensive glycosylation, and interacts with the gut microbiome, all of which influence HDL's anti-inflammatory, antioxidant, and cholesterol efflux properties. Elucidating the nuances of HDL structure and function at an individual level may unlock personalized dietary and lifestyle strategies to optimize HDL-mediated atheroprotection and reduce CVD risk.

RECENT FINDINGS

Recent human studies have demonstrated that HDL particles are key players in the reduction of CVD risk. Our review highlights the role of HDL and the importance of personalized therapeutic approaches to improve their potential for reducing CVD risk. Factors such as diet, genetics, glycosylation, and gut microbiome interactions can modulate HDL structure and function at the individual level. We emphasize that fractionating HDL into size-based subclasses and measuring particle concentration are necessary to understand HDL biology and for developing the next generation of diagnostics and biomarkers. These discoveries underscore the need to move beyond a one-size-fits-all approach to HDL management. Precision nutrition strategies that account for personalized metabolic, genetic, and lifestyle data hold promise for optimizing HDL therapies and function to mitigate CVD risk more potently. While human studies show HDL play a key role in reducing CVD risk, recent findings indicate that factors such as diet, genetics, glycosylation, and gut microbes modulate HDL function at the individual level, underscoring the need for precision nutrition strategies that account for personalized variability to optimize HDL's potential for mitigating CVD risk.