The LDL-Receptor and its Molecular Properties: From Theory to Novel Biochemical and Pharmacological Approaches in Reducing LDL-cholesterol

Aging induces region-specific dysregulation of hormone synthesis in the primate adrenal gland

Adrenal glands, vital for steroid secretion and the regulation of metabolism, stress responses and immune activation, experience age-related decline, impacting systemic health. However, the regulatory mechanisms underlying adrenal aging remain largely uninvestigated. Here we established a single-nucleus transcriptomic atlas of both young and aged primate suprarenal glands, identifying lipid metabolism and steroidogenic pathways as core processes impacted by aging. We found dysregulation in centripetal adrenocortical differentiation in aged adrenal tissues and cells in the zona reticularis region, responsible for producing dehydroepiandrosterone sulfate (DHEA-S), were highly susceptible to aging, reflected by senescence, exhaustion and disturbed hormone production. Remarkably, LDLR was downregulated in all cell types of the outer cortex, and its targeted inactivation in human adrenal cells compromised cholesterol uptake and secretion of dehydroepiandrosterone sulfate, as observed in aged primate adrenal glands. Our study provides crucial insights into endocrine physiology, holding therapeutic promise for addressing aging-related adrenal insufficiency and delaying systemic aging.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Flaxseed-derived peptides ameliorate hepatic cholesterol metabolism in Sprague-Dawley rats fed a high-cholesterol and high-fat diet

BACKGROUND

Plant peptides have been reported to have cholesterol-lowering activities. Previous research has found that ≤1 kDa flaxseed peptide (FP₅ ) reduces cholesterol absorption and synthesis in vitro. In this research, we investigated the cholesterol-lowering activity of FP₅ in Sprague-Dawley (SD) rats fed a high-cholesterol and high-fat diet. In addition, amino acid sequences of FP₅ were determined by high-performance liquid chromatography-electrospray ionization-Orbitrap mass spectrometry.

RESULTS

FP₅ supplement significantly decreased the serum and hepatic cholesterol levels and modulated the hepatic gene and protein expression of cholesterol metabolism-related enzymes or regulators (3-hydroxy-3-methylglutaryl coenzyme A reductase, Low-Density Lipoprotein Receptor (LDLR), Cholesterol 7 α-hydroxylase, Niemann-Pick C1-like 1, ATP-binding cassette transporters G5 and G8). Eleven peptides were identified from FP₅ . These peptides were characterized as hydrophobic amino acids such as leucine (L), proline (P), glycine (G), isoleucine (I) and continuous sequences, including LP, LL, LG and II, with low molecular weights.

CONCLUSION

FP₅ has a certain cholesterol-lowering activity in SD rats fed a high-cholesterol and high-fat diet. The possible mechanism for ameliorating hepatic cholesterol metabolism of FP₅ includes inhibiting hepatic cholesterol de novo synthesis, promoting the synthesis and excretion of bile acids, and inhibiting the reabsorption of bile acids during enterohepatic circulation. © 2022 Society of Chemical Industry.

Mathematical Models for Cholesterol Metabolism and Transport

Cholesterol is an essential component of eukaryotic cellular membranes. It is also an important precursor for making other molecules needed by the body. Cholesterol homeostasis plays an essential role in human health. Having high cholesterol can increase the chances of getting heart disease. As a result of the risks associated with high cholesterol, it is imperative that studies are conducted to determine the best course of action to reduce whole body cholesterol levels. Mathematical models can provide direction on this. By examining existing models, the suitable reactions or processes for drug targeting to lower whole-body cholesterol can be determined. This paper examines existing models in the literature that, in total, cover most of the processes involving cholesterol metabolism and transport, including: the absorption of cholesterol in the intestine; the cholesterol biosynthesis in the liver; the storage and transport of cholesterol between the intestine, the liver, blood vessels, and peripheral cells. The findings presented in these models will be discussed for potential combination to form a comprehensive model of cholesterol within the entire body, which is then taken as an in-silico patient for identifying drug targets, screening drugs, and designing intervention strategies to regulate cholesterol levels in the human body.

Pueraria lobata root polysaccharide alleviates glucose and lipid metabolic dysfunction in diabetic db/db mice

CONTEXT

Pueraria lobata (Willd.) Ohwi (Fabaceae) root extract can lower blood glucose levels; however, whether Pueraria lobata root polysaccharide (PLP) possesses these effects is still unknown.

OBJECTIVE

This study evaluates the therapeutic effect of PLP on diabetic metabolic syndrome.

MATERIALS AND METHODS

The db/m mice were assigned to normal control group (NC), db/db mice were divided into four groups randomly (n = 8). The db/db mice received rosiglitazone (10 mg/kg BW) or PLP (100 or 200 mg/kg BW) via oral gavage for 6 weeks. Afterward, blood glucose, insulin, and glycogen content were assayed, and insulin tolerance test (ITT), oral glucose tolerance test (OGTT) were performed. Glucose and lipid metabolism-related parameters and gene expression levels were assayed by ELISA and RT-PCR, respectively.

RESULTS

After treatment with HPLP, the values of body weight, epididymal fat, subcutaneous fat, fasting blood glucose, insulin, and HOMA-IR decreased to 45.89 ± 1.66 g, 1.65 ± 0.14 g, 1.97 ± 0.16 g, 14.84 ± 1.52 mM, 9.35 ± 0.98 mU/L, and 5.56 ± 1.26, respectively; the levels of TG, TC, LDL-C, and FFA decreased to 1.67 ± 0.11 mmol/L, 6.23 ± 0.76 mmol/L, 1.29 ± 0.07 mmol/L, and 1.71 ± 0.16 mmol/L, respectively. HPLP down-regulated PEPCK, G6PC, FOXO1, SREBP-1, and ACC mRNA expression (p < 0.01), and up-regulated GS, Akt2, PI3K, GLUT2, PPARα, and LDLR mRNA expression in the liver (p < 0.01).

DISCUSSION AND CONCLUSION

PLP exerts antidiabetic effects via activating the PI3K/AKT signalling pathway, thus improving insulin resistance, glucose, and lipid metabolism in db/db mice. Thus, PLP may be considered as a potential antidiabetic agent in clinical therapy.

Apolipoprotein B gene mutation related to familial hypercholesterolemia in an Iranian population: With or without hypothyroidism

Background:

Familial hypercholesterolemia (FH) leads to elevated low-density lipoprotein cholesterol (LDL-C) levels in plasma. Mutations of its related gene; apolipoprotein B (APOB) is seen in about two percent of the patient with FH. Thyroid disease is usually part of the exclusion criteria for the detection of FH which alters the lipid profile. We evaluated mutations in the APOB gene in patients with high LDL-C levels.

Materials and Methods:

Patients aged between 2 and 80 years with at least one LDL-C level of more than 190 mg/dl were selected (120 patients) from Isfahan Laboratories. Blood samples were obtained from all patients. Genomic DNA was extracted. Primer sequences were designed by Oligo 7.60 to amplify the desired 844 bp region of exon 26 of the APOB gene containing R3500Q and R3500W variants associated with FH.

Results:

Overall, two patients showed a heterozygous form of a common pathogenic variant in exon 26 named c. 10579 C > T (R3500W, cDNA.10707), and one patient was hypothyroidism. We also recognized another nonpathognomonic variant c. 10913G > A (rs1801701, cDNA.11041) in 13 patients, two of them were hypothyroidism.

Conclusion:

This study for the first time shows the coexistence of APOB mutation in hypothyroidism, which emphasis screening of patients with hypothyroid for FH detection.

Anti-Diabetic Effects and Mechanisms of Dietary Polysaccharides

Diabetes mellitus is a multifactorial, heterogeneous metabolic disorder, causing various health complications and economic issues, which apparently impacts the human's life. Currently, commercial diabetic drugs are clinically managed for diabetic treatment that has definite side effects. Dietary polysaccharides mainly derive from natural sources, including medicinal plants, grains, fruits, vegetables, edible mushroom, and medicinal foods, and possess anti-diabetic potential. Hence, this review summarizes the effects of dietary polysaccharides on diabetes and underlying molecular mechanisms related to inflammatory factors, oxidative stress, and diabetes in various animal models. The analysis of literature and appropriate data on anti-diabetic polysaccharide from electronic databases was conducted. In vivo and in vitro trials have revealed that treatment of these polysaccharides has hypoglycemic, hypolipidemic, antioxidant, and anti-inflammatory effects, which enhance pancreatic β-cell mass and alleviates β-cell dysfunction. It enhances insulin signaling pathways through insulin receptors and activates the PI3K/Akt pathway, and eventually modulates ERK/JNK/MAPK pathway. In conclusion, dietary polysaccharides can effectively ameliorate hyperglycemia, hyperlipidemia, low-grade inflammation, and oxidative stress in type 2 diabetes mellitus (T2DM), and, thus, consumption of polysaccharides can be a valuable choice for diabetic control.

Lipid trafficking in cardiovascular disease

The reduction of plasma apolipoprotein B (apoB) containing lipoproteins has long been pursued as the main modifiable risk factor for the development of cardiovascular disease (CVD). This has led to an intense search for strategies aiming at reducing plasma apoB-lipoproteins, culminating in reduction of overall CV risk. Despite 3 decades of progress, CVD remains the leading cause of morbidity and mortality worldwide and, as such, new therapeutic targets are still warranted. Clinical and preclinical research has moved forward from the original concept, under which some lipids must be accumulated and other removed to achieve the ideal condition in disease prevention, into the concept that mechanisms that orchestrate lipid movement between lipoproteins, cells and organelles is equally involved in CVD. As such, this review scrutinizes potentially atherogenic changes in lipid trafficking and assesses the molecular mechanisms behind it. New developments in risk assessment and new targets for the mitigation of residual CVD risk are also addressed.

Polysaccharides derived from natural sources regulate triglyceride and cholesterol metabolism: a review of the mechanisms

This paper presents a comprehensive review of hypolipidemic mechanism of polysaccharides from natural sources.