The Effects of Phellinus linteus Polysaccharide Extracts on Cholesterol Efflux in Oxidized Low-Density Lipoprotein–Loaded THP-1 Macrophages

Atheroprotective Effect of Fucoidan in THP-1 Macrophages by Potential Upregulation of ABCA1

Targeting foam cells reduces the risk and pathophysiology of atherosclerosis, of which they are one of its early hallmarks. The precise mechanism of action of fucoidan, a potential anti-atherogenic drug, is still unknown. Our objective was to assess the ability of fucoidan to regulate expression of ATP-binding cassette transporter A1 (ABCA1) in ox-LDL-induced THP-1 macrophages. Molecular docking was used to predict how fucoidan interacts with anti-foam cell markers, and further in vitro experiments were performed to evaluate the protective effect of fucoidan on modulating uptake and efflux of lipids. THP-1 macrophages were protected by 50 µg/mL of fucoidan and were then induced to form foam cells with 25 µg/mL of ox-LDL. Expression levels were assessed using RT-qPCR, and an Oil Red O stain was used to observe lipid accumulation in THP-1 macrophages. In addition, ABCA1 protein was examined by Western blot, and cellular cholesterol efflux was determined using fluorescently labeled cholesterol. Under a light microscope, decreased lipid accumulation in ox-LDL-induced-THP-1 macrophages pre-treated with fucoidan showed a significant effect, although it did not affect the expression of scavenger receptors (SR-AI and CD36). It is interesting to note that fucoidan dramatically increased the gene and protein expression of ABCA1, perhaps via the liver X receptor-α (LXR-α). Moreover, fucoidan's ability to increase and control the efflux of cholesterol from ox-LDL-induced THP-1 macrophages revealed how it may alter ABCA1's conformation and have a major effect on how it interacts with apolipoprotein A (ApoA1). In vitro results support a rationale for predicting fucoidan and its interaction with its receptor targets' predicted data, hence validating its anti-atherogenic properties and suggesting that fucoidan could be promising as an atheroprotective.

Structural diversity and bioactivity of polysaccharides from medicinal mushroom Phellinus spp.: A review

Phellinus spp., an important medicinal fungus mushroom extensively cultivated and consumed in East Asia for over 2000 years, is traditionally considered a precious food supplement and medicinal ingredient. Published studies showed that the polysaccharides are major bioactive macromolecules from Phellinus spp. (PPs) with multiple health-promoting effects, including immunomodulatory, anti-cancer, anti-inflammatory, hepatoprotective, hypoglycemic, hypolipidemic, antioxidant, and other bioactivities. Although the polysaccharides extracted from the fruiting body, mycelium, and fermentation broth of Phellinus spp. have been extensively studied for the extraction and purification methods, structural characteristics, and pharmacological activities, the knowledge for their structures and bioactivity relationship, toxicologic effects, and pharmacokinetic profile is limited. This review systematically summarizes the recent progress in the isolation and purification, chemical structures, bioactivities, and the underlying mechanisms of PPs. Information from this review provides insights into the further development of polysaccharides from PPs as therapeutic agents and functional foods.

The anti-atherosclerotic effects of natural polysaccharides: from phenomena to the main mechanisms of action

Polysaccharides (PSs) of plant origin have a variety of biological activities, anti-atherosclerotic including, but their use in atherosclerosis therapy is hindered by insufficient knowledge on the cellular and molecular mechanisms of action. In this review, the influence of several natural PSs on the function of macrophages, viral activity, and macrophage cholesterol metabolism has been discussed considering the tight interplay between these aspects in the pathogenesis of atherosclerosis. The anti-atherosclerotic activities of natural PSs related to other mechanisms have been also explored. Directions for further research of anti-atherosclerotic effects of natural PSs have been outlined, the most promising of which can be nutrigenomic studies.

Analysis of Low Molecular Weight Substances and Related Processes Influencing Cellular Cholesterol Efflux

Cholesterol efflux is the key process protecting the vascular system from the development of atherosclerotic lesions. Various extracellular and intracellular events affect the ability of the cell to efflux excess cholesterol. To explore the possible pathways and processes that promote or inhibit cholesterol efflux, we applied a combined cheminformatic and bioinformatic approach. We performed a comprehensive analysis of published data on the various substances influencing cholesterol efflux and found 153 low molecular weight substances that are included in the Chemical Entities of Biological Interest (ChEBI) database. Pathway enrichment was performed for substances identified within the Reactome database, and 45 substances were selected in 93 significant pathways. The most common pathways included the energy-dependent processes related to active cholesterol transport from the cell, lipoprotein metabolism and lipid transport, and signaling pathways. The activators and inhibitors of cholesterol efflux were non-uniformly distributed among the different pathways: the substances influencing ‘biological oxidations’ activate cholesterol efflux and the substances influencing ‘Signaling by GPCR and PTK6’ inhibit efflux. This analysis may be used in the search and design of efflux effectors for therapies targeting structural and functional high-density lipoprotein deficiency.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

A Review: The Bioactivities and Pharmacological Applications of Phellinus linteus

Phellinus linteus is a popular medicinal mushroom that is widely used in China, Korea, Japan, and other Asian countries. P. linteus comprises various bioactive components, such as polysaccharides, triterpenoids, phenylpropanoids, and furans, and has proven to be an effective therapeutic agent in traditional Chinese medicine for the treatment and the prevention of various diseases. A number of studies have reported that P. linteus possesses many biological activities useful for pharmacological applications, including anticancer, anti-inflammatory, immunomodulatory, antioxidative, and antifungal activities, as well as antidiabetic, hepatoprotective, and neuroprotective effects. This review article briefly presents the recent progress made in understanding the bioactive components, biological activities, pharmacological applications, safety, and prospects of P. linteus, and provides helpful references and promising directions for further studies of P. linteus.

LIGHT is increased in patients with coronary disease and regulates inflammatory response and lipid metabolism in oxLDL-induced THP-1 macrophages

Inflammation is critical for the progression of hyperlipidemia. Although the exact mechanism through which inflammation affects hyperlipidemia is not very clear, evidence suggests that the tumor necrosis factor superfamily member 14 (TNFSF14/LIGHT)LIGHT might regulate lipid metabolism. In this study we investigated the expression of LIGHT in patients with different stages of coronary disease. The expression of lipid metabolism-related enzymes and inflammation-related proteins were further explored in oxidized low-density lipoproteins (oxLDL)-induced THP-1 macrophages. We found that LIGHT is highly expressed and companied with severe inflammations in patients with coronary disease. LIGHT significantly enhanced inflammation response in oxLDL-induced THP-1 macrophages. We further demonstrated that LIGHT markedly decreased the levels of lipolytic genes and increased the expressions of lipogenic genes in oxLDL-induced THP-1 macrophages. In addition, our results showed that LIGHT exerts its pro-inflammatory and pro-lipogenesis roles through activating nuclear factor-kappa B (NF-κB) signaling pathway. Taken together our study has demonstrated that LIGHT NF-κB-dependently exacerbates inflammation response and promotes lipid accumulation, and provided a new potential target for treatment of hyperlipidemia-related disease.