Low-density Lipoprotein Receptor Research Articles

Evaluation of the pathogenic variants in the APOB, LDLR, and APOE genes in the Czech subjects: Preliminary report

Evaluation of the pathogenic variants in the APOB, LDLR, and APOE genes in the Czech subjects: Preliminary report

Efficacy of evinacumab by low-density lipoprotein receptor genotype and function in patients with homozygous familial hypercholesterolaemia: A subanalysis from the ELIPSE open-label extension study

Efficacy of evinacumab by low-density lipoprotein receptor genotype and function in patients with homozygous familial hypercholesterolaemia: A subanalysis from the ELIPSE open-label extension study

Carbamoyl phosphate synthase 1 (CPS1), a mitochondrial enzyme of the urea cycle, is involved in LDL receptor modulation: In vitro studies

Carbamoyl phosphate synthase 1 (CPS1), a mitochondrial enzyme of the urea cycle, is involved in LDL receptor modulation: In vitro studies

Optimo-LDLr: An integrated in silico model with enhanced predictive power for LDL receptor variants, unraveling hot spot pathogenic residues

Optimo-LDLr: An integrated in silico model with enhanced predictive power for LDL receptor variants, unraveling hot spot pathogenic residues

Pharmacological modulation of LDL receptor by small interfering RNA and antibodies anti-PCSK9: An in vitro study

Pharmacological modulation of LDL receptor by small interfering RNA and antibodies anti-PCSK9: An in vitro study

LIPC-E97G gain-of-function variant protects from dyslipidemia and atherosclerosis in mice independently of the LDL receptor

LIPC-E97G gain-of-function variant protects from dyslipidemia and atherosclerosis in mice independently of the LDL receptor

Resistance to drug therapy made it possible to identify a digenic mutation of LDLR gene in heterozygosity

Resistance to drug therapy made it possible to identify a digenic mutation of LDLR gene in heterozygosity

Deletions in the 3’UTR of the LDLR gene: A genetic cause of familial hypobetalipoproteinemia

Deletions in the 3’UTR of the LDLR gene: A genetic cause of familial hypobetalipoproteinemia

A Rapid and Scalable Multiplex PCR-Based Next-Generation Amplicon Sequencing Method for Familial Hypercholesterolemia Genetic Screening.

Familial hypercholesterolemia (FH) is a frequently underdiagnosed genetic disorder characterized by elevated low-density lipoprotein (LDL) levels. Genetic testing of LDLR, APOB, and PCSK9 genes can identify variants in up to 80% of clinically diagnosed patients. However, limitations in time, scalability, and cost have hindered effective next-generation sequencing of these genes. Additionally, pharmacogenomic variants are associated with statin-induced adverse effects in FH patients. To address these challenges, we developed a multiplex primer-based amplicon sequencing approach for FH genetic testing. Multiplex primers were designed for the exons of the LDLR, APOB, and PCSK9 genes, as well as for pharmacogenomic variants rs4149056 (SLCO1B1:c.521T > A), rs2306283 (SLCO1B1:c.388A > G), and rs2231142 (ABCG2:c.421C > A). Analytical validation using samples with known pathogenic variants and clinical validation with 12 FH-suspected probands were conducted. Library preparation was based on a bead-based tagmentation method, and sequencing was conducted on the NovaSeq 6000 platform. Our approach ensured no amplicon dropouts, with over 100× coverage on each amplicon. Known variants in 2 samples were successfully detected. Further, we identified one heterozygous LDLR (p.Glu228Ter) variant and 2 homozygous cases of LDLR (p.Lys294Ter) and LDLR (p.Ser177Leu) variants in patients. Pharmacogenomic analysis revealed that overall 3 patients may require reduced statin doses. Our approach offered reduced library preparation time (approximately 3 h), greater scalability, and lower costs (under $50) for FH genetic testing. Our method effectively sequences LDLR, APOB, and PCSK9 genes including pharmacogenomic variants that will guide appropriate screening and statin dosing, thus increasing both efficiency and affordability.

PCSK9 inhibitor effectively alleviated cognitive dysfunction in a type 2 diabetes mellitus rat model.

The incidence of diabetes-associated cognitive dysfunction (DACD) is increasing; however, few clinical intervention measures are available for the prevention and treatment of this disease. Research has shown that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, particularly SBC-115076, have a protective effect against various neurodegenerative diseases. However, their role in DACD remains unknown. In this study, we aimed to explore the impact of PCSK9 inhibitors on DACD. Male Sprague-Dawley (SD) rats were used to establish an animal model of type 2 diabetes mellitus (T2DM). The rats were randomly divided into three groups: the Control group (Control, healthy rats, n = 8), the Model group (Model, rats with T2DM, n = 8), and the PCSK9 inhibitor-treated group (Treat, T2DM rats treated with PCSK9 inhibitors, n = 8). To assess the spatial learning and memory of the rats in each group, the Morris water maze (MWM) test was conducted. Hematoxylin-eosin staining and Nissl staining procedures were performed to assess the structural characteristics and functional status of the neurons of rats from each group. Transmission electron microscopy was used to examine the morphology and structure of the hippocampal neurons. Determine serum PCSK9 and lipid metabolism indicators in each group of rats. Use qRT-PCR to detect the expression levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) in the hippocampal tissues of each group of rats. Western blot was used to detect the expression of PCSK9 and low-density lipoprotein receptor (LDLR) in the hippocampal tissues of rats. In addition, a 4D label-free quantitative proteomics approach was used to analyse protein expression in rat hippocampal tissues. The expression of selected proteins in hippocampal tissues was verified by parallel reaction monitoring (PRM) and immunohistochemistry (IHC). The results showed that the PCSK9 inhibitor alleviated cognitive dysfunction in T2DM rats. PCSK9 inhibitors can reduce PCSK9, total cholesterol (TC), and low-density lipoprotein (LDL) levels in the serum of T2DM rats. Meanwhile, it was found that PCSK9 inhibitors can reduce the expression of PCSK9, IL-1β, IL-6, and TNF-α in the hippocampal tissues of T2DM rats, while increasing the expression of LDLR. Thirteen potential target proteins for the action of PCSK9 inhibitors on DACD rats were identified. PRM and IHC revealed that PCSK9 inhibitors effectively counteracted the downregulation of transthyretin in DACD rats. This study uncovered the target proteins and specific mechanisms of PCSK9 inhibitors in DACD, providing an experimental basis for the clinical application of PCSK9 inhibitors for the potential treatment of DACD.

Contrasting effects of intracellular and extracellular human PCSK9 on inflammation, lipid alteration and cell death

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the major regulators of low-density lipoprotein receptor (LDLR). Information on role and regulation of PCSK9 in lung is very limited. Our study focuses on understanding the role and regulation of PCSK9 in the lung. PCSK9 levels are higher in Bronchoalveolar lavage fluid (BALF) of smokers with or without chronic obstructive pulmonary diseases (COPD) compared to BALF of nonsmokers. PCSK9-stimulated cells induce proinflammatory cytokines and activation of MAPKp38. PCSK9 transcripts are highly expressed in healthy individuals compared to COPD, pulmonary fibrosis or pulmonary systemic sclerosis. Cigarette smoke extract reduce PCSK9 levels in undifferentiated pulmonary bronchial epithelial cells (PBEC) but induce in differentiated PBEC. PCSK9 inhibition affect biological pathways, induces lipid peroxidation, and higher level of apoptosis in response to staurosporine. Our results suggest that higher levels of PCSK9 in BALF acts as an inflammatory marker. Furthermore, extracellular and intracellular PCSK9 play different roles.

Protein Corona-Directed Cellular Recognition and Uptake of Polyethylene Nanoplastics by Macrophages.

The widespread use of plastic products in daily life has raised concerns about the health hazards associated with nanoplastics (NPs). When exposed, NPs are likely to infiltrate the bloodstream, interact with plasma proteins, and trigger macrophage recognition and clearance. In this study, we focused on establishing a correlation between the unique protein coronal signatures of high-density (HDPE) and low-density (LDPE) polyethylene (PE) NPs with their ultimate impact on macrophage recognition and cytotoxicity. We observed that low-density and high-density lipoprotein receptors (LDLR and SR-B1), facilitated by apolipoproteins, played an essential role in PE-NP recognition. Consequently, PE-NPs activated the caspase-3/GSDME pathway and ultimately led to pyroptosis. Advanced imaging techniques, including label-free scattered light confocal imaging and cryo-soft X-ray transmission microscopy with 3D-tomographic reconstruction (nano-CT), provided powerful insights into visualizing NPs-cell interactions. These findings underscore the potential risks of NPs to macrophages and introduce analytical methods for studying the behavior of NPs in biological systems.

The low-density lipoprotein receptor contributes to carotenoid homeostasis by regulating tissue uptake and fecal elimination

ObjectiveCarotenoids are lipophilic plant molecules with antioxidant properties. Some carotenoids such as β-carotene also serve as vitamin A precursors, playing a key role in human health. Carotenoids are transported in lipoproteins with other lipids such as cholesterol, however, the mechanisms responsible for carotenoid storage in tissues and their non-enzymatic elimination remain relatively unexplored. The goal of this study was to examine the contribution of the low-density lipoprotein receptor (LDLR) in the bodily distribution and disposal of carotenoids. MethodsWe employed mice lacking one or both carotenoid-cleaving enzymes as suitable models for carotenoid accumulation. We examined the contribution of LDLR in carotenoid distribution by crossbreeding these mice with Ldlr-/- mice or overexpressing LDLR in the liver. ResultsOur results show that LDLR plays a dual role in carotenoid homeostasis by simultaneously favoring carotenoid storage in the liver and adipose tissue while facilitating their fecal elimination. ConclusionsOur results highlight a novel role of the LDLR in carotenoid homeostasis, and unveil a previously unrecognized disposal pathway for these important bioactive molecules.

The receptor VLDLR binds Eastern Equine Encephalitis virus through multiple distinct modes

Eastern Equine Encephalitis virus (EEEV) is an alphavirus that can cause severe diseases in infected humans. The very low-density lipoprotein receptor (VLDLR) was recently identified as a receptor of EEEV. Herein, we performed cryo-electron microscopy structural and biochemistry studies on the specific interactions between EEEV and VLDLR. Our results show that VLDLR binds EEEV at three different sites A, B and C through its membrane-distal LDLR class A (LA) repeats. Site A is located in the cleft in between the E1-E2 heterodimers. Site B is located near the connecting β ribbon of E2 and is in proximity to site A, while site C is on the domain B of E2. The binding of VLDLR LAs to EEEV is in complex modes, including the LA1-2 and LA3-5 mediated two major modes. Disruption of the LA1-2 mediated binding significantly affect the cell attachment of EEEV. However, the mutation W132G of VLDLR impairs the binding of LA3, drives the switch of the binding modes, and significantly enhances the attachment of EEEV to the cell. The W132G variant of VLDLR could be identified in human genome and SNP sequences, implying that people with similar mutations in VLDLR may be highly susceptible to EEEV infection.

Molecular Determinants for Photodynamic Therapy Resistance and Improved Photosensitizer Delivery in Glioma.

Gliomas account for 24% of all the primary brain and Central Nervous System (CNS) tumors. These tumors are diverse in cellular origin, genetic profile, and morphology but collectively have one of the most dismal prognoses of all cancers. Work is constantly underway to discover a new effective form of glioma therapy. Photodynamic therapy (PDT) may be one of them. It involves the local or systemic application of a photosensitive compound-a photosensitizer (PS)-which accumulates in the affected tissues. Photosensitizer molecules absorb light of the appropriate wavelength, initiating the activation processes leading to the formation of reactive oxygen species and the selective destruction of inappropriate cells. Research focusing on the effective use of PDT in glioma therapy is already underway with promising results. In our work, we provide detailed insights into the molecular changes in glioma after photodynamic therapy. We describe a number of molecules that may contribute to the resistance of glioma cells to PDT, such as the adenosine triphosphate (ATP)-binding cassette efflux transporter G2, glutathione, ferrochelatase, heme oxygenase, and hypoxia-inducible factor 1. We identify molecular targets that can be used to improve the photosensitizer delivery to glioma cells, such as the epithelial growth factor receptor, neuropilin-1, low-density lipoprotein receptor, and neuropeptide Y receptors. We note that PDT can increase the expression of some molecules that reduce the effectiveness of therapy, such as Vascular endothelial growth factor (VEGF), glutamate, and nitric oxide. However, the scientific literature lacks clear data on the effects of PDT on many of the molecules described, and the available reports are often contradictory. In our work, we highlight the gaps in this knowledge and point to directions for further research that may enhance the efficacy of PDT in the treatment of glioma.

Dysregulated lipid metabolism and intervertebral disc degeneration: the important role of ox-LDL/LOX-1 in endplate chondrocyte senescence and calcification

BackgroundLipid metabolism disorders are associated with degeneration of multiple tissues and organs, but the mechanism of crosstalk between lipid metabolism disorder and intervertebral disc degeneration (IDD) has not been fully elucidated. In this study we aim to investigate the regulatory mechanism of abnormal signal of lipid metabolism disorder on intervertebral disc endplate chondrocyte (EPC) senescence and calcification. MethodsHuman intervertebral disc cartilage endplate tissue, cell model and rat hyperlipemia model were performed in this study. Histology and immunohistochemistry were used to human EPC tissue detection. TMT-labelled quantitative proteomics was used to detect differential proteins, and MRI, micro-CT, safranin green staining and immunofluorescence were performed to observe the morphology and degeneration of rat tail intervertebral discs. Flow cytometry, senescence-associated β-galactosidase staining, alizarin red staining, alkaline phosphatase staining, DCFH-DA fluorescent probe, and western blot were performed to detect the expression of EPC cell senescence, senescence-associated secretory phenotype, calcification-related proteins and the activation of cell senescence-related signaling pathways. ResultsOur study found that the highly expressed oxidized low-density lipoprotein (ox-LDL) and Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) in human degenerative EPC was associated with hyperlipidemia (HLP). TMT-labelled quantitative proteomics revealed enriched pathways such as cell cycle regulation, endochondral bone morphogenesis and inflammation. The rat model revealed that HLP could induce ox-LDL, LOX-1, senescence and calcification markers high expression in EPC. Moreover, we demonstrated that ox-LDL-induced EPCs senescence and calcification were dependent on the LOX-1 receptor, and the ROS/P38-MAPK/NF-κB signaling pathway was implicated in the regulation of senescence induced by ox-LDL/LOX-1 in cell model.ConclusionsSo our study revealed that ox-LDL/LOX-1-induced EPCs senescence and calcification through ROS/P38-MAPK/NF-κB signaling pathway, providing information on understanding the link between lipid metabolism disorders and IDD.

Therapeutic biomaterials with liver X receptor agonists based on the horizon of material biology to regulate atherosclerotic plaque regression in situ for devices surface engineering.

Percutaneous coronary interventional is the main treatment for coronary atherosclerosis. At present, most studies focus on blood components and smooth muscle cells to achieve anticoagulation or anti-proliferation effects, while the mediated effects of materials on macrophages are also the focus of attention. Macrophage foam cells loaded with elevated cholesterol is a prominent feature of atherosclerotic plaque. Activation of liver X receptor (LXR) to regulate cholesterol efflux and efferocytosis and reduce the number of macrophage foam cells in plaque is feasible for the regression of atherosclerosis. However, cholesterol efflux promotion remains confined to targeted therapies. Herein, LXR agonists (GW3965) were introduced on the surface of the material and delivered in situ to atherogenic macrophages to improve drug utilization for anti-atherogenic therapy and plaque regression. LXR agonists act as plaque inhibition mediated by multichannel regulation macrophages, including lipid metabolism (ABCA1, ABCG1 and low-density lipoprotein receptor), macrophage migration (CCR7) and efferocytosis (MerTK). Material loaded with LXR agonists significantly reduced plaque burden in atherosclerotic model rats, most importantly, it did not cause hepatotoxicity and adverse reactions such as restenosis and thrombosis after material implantation. Both in vivo and in vitro evaluations confirmed its anti-atherosclerotic capability and safety. Overall, multi-functional LXR agonist-loaded materials with pathological microenvironment regulation effect are expected to be promising candidates for anti-atherosclerosis and have potential applications in cardiovascular devices surface engineering.

The PerioGene North Study Uncovers Serum Proteins Related to Periodontitis

The sequalae of periodontitis include irreversible degradation of tooth-supporting structures and circulatory spread of inflammatory mediators. However, the serum protein profile in periodontitis is not well described, which is partly attributable to the limited number of studies based on large and well-characterized periodontitis cohorts. This study aims to identify novel, circulating inflammation-related proteins associated with periodontitis within the PerioGene North case-control study, which includes 478 cases with severe periodontitis and 509 periodontally healthy controls. The serum concentrations of high-sensitivity C-reactive protein (hs-CRP) and a panel of 45 inflammation-related proteins were analyzed using targeted proteomics. A distinguishable serum protein profile was evident in periodontitis cases. The protein pattern could separate cases from controls with a sensitivity of 0.81 and specificity of 0.81 (area under the curve = 0.87). Adjusted levels for hs-CRP and 24 of the 45 proteins were different between cases and controls. High levels of hs-CRP and matrix metalloproteinase–12, and low levels of epidermal growth factor (EGF) and oxidized low-density lipoprotein receptor 1 (OLR-1) were detected among the cases. Furthermore, the levels of C-C motif chemokine–19, granulocyte colony-stimulating factor–3 (CSF-3), interleukin-7 (IL-7), and hs-CRP were significantly higher in cases with a high degree of gingival inflammation. The levels of CSF-3 and tumor necrosis factor ligand superfamily member–10 TNFSF-10 were higher in cases with many deep periodontal pockets. The PerioGene North study includes detailed clinical periodontal data and uncovers a distinct serum protein profile in periodontitis. The findings of lower EGF and OLR-1 among the cases are highlighted, as this has not been presented before. The role of EGF and OLR-1 in periodontitis pathogenesis and as possible future biomarkers should be further explored.

Abstract Tu016: Alleviating Aortic Valve Calcification By Blocking TNFα Receptors

Background: Tumor Necrosis Factor-alpha (TNFα) is a key inflammatory cytokine involved in calcific aortic valve disease (CAVD). Following mechanical stress, activated monocytes, macrophages induce TNFα signaling in aortic valve (AoV). The activated TNFα binds to its own receptors, TNFR1 and TNFR2, in which TNFR1 has a death domain likely to cause cell death in AoV. Subsequently, the release of extracellular vesicles (calcium and inorganic phosphates) following inflammatory process results in valve calcification and stenosis. Hypothesis: Blocking TNFα-mediated inflammation by genetic knockout of Tnfr1/Tnfr2 slowdown CAVD progression in mice. Methods and Results: Using a mouse model of CAVD with deletion of Ldlr, low-density lipoprotein receptor, we compared the disease progression in mice fed with standard and high fat diet. To get better understanding on the role of TNFα in CAVD, Ldlr -/- mice (3 months old) on the TNFR1 and TNFR2 knockout background, were also fed with high fat diet for 3 months ( Ldlr -/- ; Tnfr1 -/- : Tnfr2 -/- ). Aortic valve function was analyzed by using echocardiogram and it showed decreased AoV velocity and increased ejection fraction in Ldlr -/- ; Tnfr1 -/- : Tnfr2 -/- compared to Ldlr -/- ; Tnfr1 +/- : Tnfr2 +/- group. The pathological changes such as fibrosis, calcium and collagen deposition seen under routine and specialized histological staining methods were reduced in TNF receptors knockout group. Next, using customized designed for PCR arrays, we examined the expression of 62 candidate genes involved in inflammation, apoptosis, extracellular matrix remodeling or aortic valve stenosis pathways. The top downregulated genes in the Ldlr -/- ; Tnfr1 -/- : Tnfr2 -/- group compared to Ldlr -/- ; Tnfr1 +/- : Tnfr2 +/- group are (Col3a1, MMp7, Klk1) whereas the top upregulated gene are (Igf1r and MMp14). We are currently validating these findings by using qPCR and immunofluorescence. Conclusion: Our findings reveal blocking TNFα signaling receptors downregulate the genes related to inflammatory cytokine activation and aortic valve stenosis in the Ldlr knockout mice fed with high fat diet. Blockage of TNFα likely reduces apoptosis and inflammation while improves extracellular matrix remodeling to slowdown CAVD progression. Our findings thus suggest a new therapeutic strategy for CAVD.

Abstract Mo102: Swine Model of Heart Failure with Preserved Ejection Fraction Driven by Lipoprotein Lipase Inhibition and Enhanced Cardiac Low-Density Lipoprotein Receptor Expression

Background: Heart failure with preserved ejection fraction (HFpEF) poses an escalating public health threat, marked by growing incidence and high mortality. In the cardiometabolic phenogroup of HFpEF that includes diabetes and obesity, intramyocardial lipid content is a prognostic indicator of diastolic dysfunction and adverse outcome. Our group recently reported a mouse model of cardiometabolic HFpEF wherein myocardial lipotoxicity was induced by systemic inhibition of lipoprotein lipase (LPL) with Poloxamer 407 (P407) and cardiac overexpression of the LDL receptor (LDLR), conditions that have been documented in clinical HFpEF. The model demonstrates myocardial lipid accumulation, fibrosis, arrhythmia, and diastolic dysfunction. To reproduce this model in large animals we implemented the same protocol in pigs. Methods: Female Yorkshire swine (~25 Kg) were subjected to one of two protocols including: 1) single intracoronary (i.c.) injection of 10 13 AAV9-cTnT-LDLR particles and biweekly intraperitoneal (i.p.) P407 at 1g/Kg, (high dose, n=2), or 2) Double i.c. injections of 10 13 AAV9-cTnT-LDLR particles and biweekly i.p. P407 at 0.25g/Kg) (low dose, n=2). Cardiac structure and function were evaluated by MRI, and hemodynamics measured by PV-Loop at baseline, 4, 8, and 12 weeks. Blood was collected biweekly for complete blood count (CBC), basic biochemistry, and liver and lipid panels. Tissues were collected for protein and histopathological analysis. Results: In both strategies, the animals developed high LDL-cholesterol and cardiac hypertrophy with preserved EF. High dose P407 led to higher triglycerides, VLDL, HDL, liver injury (ALT > 200U/L), and steatosis at 4 weeks. One of the 2 pigs died at 3 weeks. Low dose P407 and high dose viral particles induced HFpEF at ~12 weeks with increased LV mass, relative wall thickness, end-diastolic pressure, and tau. Serum LDL-C accumulated from an initial value of 161 to 344.5mg/dL at 12 weeks. No significant liver injury was present until week 12 (ALT<88 U/L, AST<59 U/L). Both strategies did not exhibit abnormalities in CBC or other biochemical parameters. Conclusions: Low dose inhibition of LPL combined with cardiac overexpression of LDLR confers HFpEF in swine.