Fucoidan reduces lipid accumulation by promoting foam cell autophagy via TFEB

A novel strategy to enhance inhibition of Hela cervical cancer by combining Lentinus β-glucan and autophagic flux blockage

Lentinus β-D-glucan (LNT), derived from artificially cultured mushrooms of Lentinus edodes, shows an important yet incompletely understood biological functions in cancer. In this work, the chemical structure of the refined LNT comprising a β-D-(1, 6)-branched β-D-(1,3)-glucan was further clarified via 1D- and 2D-NMR with high resolution, and its drug resistance resulted from autophagy in human cervical cancer (CC) Hela cells besides its anti-cancer function were revealed in vitro and in vivo. In detail, LNT destroyed cellular homeostasis by significantly increasing the intracellular Ca2+ levels and promoted autophagic flux in vitro Hela cells, which was found to at least partially depend on the PI3K/Akt/mTOR-mediated pathway by up-regulating LC3-II levels and down-regulating the expression of p62, PI3K, p-Akt, and mTOR in Hela cells-transplanted BALB/c nude mice. In particular, LNT-induced autophagy led to a drug resistance against LNT-induced proliferation inhibition and apoptosis in Hela cells, and the co-treatment of autophagy inhibitors and LNT significantly enhanced the inhibition of Hela cells and tumor growth in vitro and in vivo. Therefore, the combination of LNT and autophagy inhibitors will be a novel therapeutic strategy to reduce the resistance and improve the prognosis of CC patients in the clinical.

Black phosphorus quantum dots prevent atherosclerosis in high-fat diet-fed apolipoprotein E knockout mice

Atherosclerosis (AS) is the main pathological basis of cardiovascular diseases such as coronary heart disease. Black phosphorus quantum dots (BPQDs) are a novel nanomaterial with good optical properties and biocompatibility, which was applied in the treatment of AS in mice, with good results shown in our previous study. In this study, BPQDs were injected into high-fat diet-fed apolipoprotein E knockout mice as a preventive drug for 12 weeks. Simvastatin, a classic preventive drug for AS, was used as a control to verify the preventive effect of BPQDs. The results showed that after preventive treatment with BPQDs, the plaque area in mice was significantly reduced, the vascular elasticity was increased, and serum lipid levels were significantly lower than those in the model group. To explore the mechanism, macrophages were induced to become foam cells using oxidized low-density lipoprotein. We found that BPQDs treatment could increase cell autophagy, thereby regulating intracellular lipid metabolism. Taken together, these data revealed that BPQDs may serve as a functional drug in preventing the development of AS.

MiR-223 enhances lipophagy by suppressing CTSB in microglia following lysolecithin-induced demyelination in mice

BACKGROUND

Lipid droplet (LD)-laden microglia is a key pathological hallmark of multiple sclerosis. The recent discovery of this novel microglial subtype, lipid-droplet-accumulating microglia (LDAM), is notable for increased inflammatory factor secretion and diminished phagocytic capability. Lipophagy, the autophagy-mediated selective degradation of LDs, plays a critical role in this context. This study investigated the involvement of microRNAs (miRNAs) in lipophagy during demyelinating diseases, assessed their capacity to modulate LDAM subtypes, and elucidated the potential underlying mechanisms involved.

METHODS

C57BL/6 mice were used for in vivo experiments. Two weeks post demyelination induction at cervical level 4 (C4), histological assessments and confocal imaging were performed to examine LD accumulation in microglia within the lesion site. Autophagic changes were observed using transmission electron microscopy. miRNA and mRNA multi-omics analyses identified differentially expressed miRNAs and mRNAs under demyelinating conditions and the related autophagy target genes. The role of miR-223 in lipophagy under these conditions was specifically explored. In vitro studies, including miR-223 upregulation in BV2 cells via lentiviral infection, validated the bioinformatics findings. Immunofluorescence staining was used to measure LD accumulation, autophagy levels, target gene expression, and inflammatory mediator levels to elucidate the mechanisms of action of miR-223 in LDAM.

RESULTS

Oil Red O staining and confocal imaging revealed substantial LD accumulation in the demyelinated spinal cord. Transmission electron microscopy revealed increased numbers of autophagic vacuoles at the injury site. Multi-omics analysis revealed miR-223 as a crucial regulatory gene in lipophagy during demyelination. It was identified that cathepsin B (CTSB) targets miR-223 in autophagy to integrate miRNA, mRNA, and autophagy gene databases. In vitro, miR-223 upregulation suppressed CTSB expression in BV2 cells, augmented autophagy, alleviated LD accumulation, and decreased the expression of the inflammatory mediator IL-1β.

CONCLUSION

These findings indicate that miR-223 plays a pivotal role in lipophagy under demyelinating conditions. By inhibiting CTSB, miR-223 promotes selective LD degradation, thereby reducing the lipid burden and inflammatory phenotype in LDAM. This study broadens the understanding of the molecular mechanisms of lipophagy and proposes lipophagy induction as a potential therapeutic approach to mitigate inflammatory responses in demyelinating diseases.

A comparative study of the hypolipidemic effects and mechanisms of action of Laminaria japonica- and Ascophyllum nodosum-derived fucoidans in apolipoprotein E-deficient mice

The structural characteristics of fucoidans exhibit species and regional diversity. Previous studies have demonstrated that Laminaria japonica- and Ascophyllum nodosum-derived fucoidans have type I and type II fucosyl chains, respectively. These chemical differences may contribute to distinct hypolipidemic effects and mechanisms of action. Chemical analysis demonstrated that the percentage contents of sulfate, glucuronic acid, and galactose were higher in L. japonica-derived fucoidans than those of A. nodosum-derived fucoidans. In hyperlipidemic apolipoprotein E-deficient mice, both A. nodosum- and L. japonica-derived fucoidans significantly decreased the plasma and hepatic levels of total cholesterol and triglyceride, leading to the reduction of atherosclerotic plaques. Western blotting experiments demonstrated that these fucoidans significantly enhanced the expression and levels of scavenger receptor B type 1, cholesterol 7 alpha-hydroxylase A1, and peroxisome proliferator-activated receptor (PPAR)-α, contributing to circulating lipoprotein clearance and fatty acid degradation, respectively. Differentially, L. japonica-derived fucoidan significantly increased the LXR/ATP-binding cassette G8 signaling pathway in the small intestine, as revealed by real-time quantitative PCR, which may lead to further cholesterol and other lipid excretion. Collectively, these data are useful for understanding the hypolipidemic mechanisms of action of seaweed-derived fucoidans, and their potential application for the prevention and/or treatment of atherosclerotic cardiovascular diseases.

Marine Compounds and Age-Related Diseases: The Path from Pre-Clinical Research to Approved Drugs for the Treatment of Cardiovascular Diseases and Diabetes

Ageing represents a main risk factor for several pathologies. Among them, cardiovascular diseases (CVD) and type 2 diabetes mellitus (T2DM) are predominant in the elderly population and often require prolonged use of multiple drugs due to their chronic nature and the high proportion of co-morbidities. Hence, research is constantly looking for novel, effective molecules to treat CVD and T2DM with minimal side effects. Marine active compounds, holding a great diversity of chemical structures and biological properties, represent interesting therapeutic candidates to treat these age-related diseases. This review summarizes the current state of research on marine compounds for the treatment of CVD and T2DM, from pre-clinical studies to clinical investigations and approved drugs, highlighting the potential of marine compounds in the development of new therapies, together with the limitations in translating pre-clinical results into human application.

Fucoidan-induced reduction of lipid accumulation in foam cells through overexpression of lysosome genes

Atherosclerosis (AS) is the common basis for the onset of cardiovascular events. The lipid metabolism theory considers foam cell formation as an important marker for the initiation of AS. Fucoidan is an acidic polysaccharide that can reduce lipid accumulation in foam cells. Studies show that tea polysaccharides can be transported to lysosomes via the tubulin pathway. However, the specific mechanism of action of fucoidan on foam cells has not been extensively studied. Therefore, we further explored the mechanism of action of fucoidan and evaluated whether it could reduce lipid accumulation in foam cells by affecting the expression of lysosomal pathway-related genes and proteins. In this study, three inhibitors, CPZ, EIPA, and colchicine, were used to inhibit endocytosis, macropinocytosis, and the tubulin pathway, respectively, to study the pathways of action. Transcriptomics and proteomics analysis, as well as western blotting and qRT-PCR were used to determine the effects of fucoidan and the inhibitors on lysosomal genes and proteins. Fucoidan could enter foam cells through both endocytosis and via macropinocytosis, and then further undergo intracellular transport via the tubulin pathway. After fucoidan treatment, the expression of lysosomal pathway-related genes and proteins including LAMP2, AP3, AP4, MCOLN1, and TFEB in foam cells increased significantly (P < 0.01). However, the expression of lysosomal genes and proteins after colchicine intervention was comparable with that in the model group. Therefore, the tubulin pathway inhibited by colchicine is an important pathway for the transport and distribution of fucoidan within cells. In summary, fucoidan may be transported to lysosomes via the tubulin pathway and may enhance the expression of lysosomal genes, promoting autophagy, thereby accelerating lipid clearance in foam cells. Due to its significant lipid-lowering effect, it can be used in the clinical treatment of AS.

TFEB regulates the odontoblastic differentiation of dental pulp stem cells by promoting a positive feedback loop between mitophagy and glycolysis

OBJECTIVE

To evaluate the regulatory effect of transcription factor EB (TFEB) on the odontoblastic differentiation of dental pulp stem cells(DPSCs) in vivo and in vitro.

DESIGNS

RNA-seq was used to detect differentially expressed genes in differentiated DPSCs. Lysosomes and the expression of the related gene TFEB were examined in DPSCs. DPSCs were then transfected with lentivirus for TFEB-overexpression. Cell proliferation was detected using CCK-8 and EdU assays, while cell differentiation was detected using ALP and ARS detection kits. Subsequently, mitophagy and cell metabolism were examined using TEM and Seahorse. An odontoblastic differentiation model was constructed subcutaneously in nude mice. Finally, the effects of glycolysis and mitophagy inhibitors were evaluated on odontoblastic differentiation and the associated mechanisms were explored.

RESULTS

TFEB overexpression promoted a significant increase in ALP activity and the expression of differentiation-related genes in DPSCs, while it inhibited cell proliferation. In vivo, TFEB overexpression caused higher bone volume/trabecular volume(BV/TV), and an increase in collagen formation and heightened DMP-1 expression. Furthermore, Seahorse flux analysis demonstrated that TFEB promoted metabolic reprogramming. Transmission electron microscope(TEM) results indicated an increase in mitochondrial autophagosomes after TFEB overexpression, and the expression of mitophagy-related genes was also elevated. The odontoblastic differentiation of DPSCs promoted by TFEB overexpression was suppressed after the addition of 2-DG and Midiv-1. Addition of Midiv-1 reduced the glycolytic rate of DPSCs, while addition of 2-DG also decreased the mitophagy level of the cells.

CONCLUSIONS

Our results showed that TFEB promoted the odontoblastic differentiation of DPSCs and identified mitophagy and metabolic reprogramming as a positive feedback loop.

Fucoidan alleviated dextran sulfate sodium-induced ulcerative colitis with improved intestinal barrier, reshaped gut microbiota composition, and promoted autophagy in male C57BL/6 mice

Although previous research has unveiled the remedial effects of fucoidan, an extract from marine algae, on ulcerative colitis (UC), the precise mechanisms remain elusive. Animal studies have suggested a connection between autophagy and the beneficial influences of fucoidan intervention. We hypothesized that fucoidan's alleviative effects on dextran sulfate sodium (DSS)-induced UC could be ascribed to autophagy. For our study, we chose 36 male C57BL/6 mice and administered 100 or 400 mg/(kg/body weight/day) of fucoidan via gavage for 5 consecutive weeks. During the last week, the mice were given 3% DSS in drinking water to induce UC. In contrast to the DSS-induced UC model, fucoidan intervention prevented DSS-induced body weight loss, mitigated colon shortening, improved colon mucosa damage, enhanced the intestinal barrier, and reduced serum inflammatory factor concentrations. Furthermore, fucoidan intervention reshaped the gut microbiota compositions, increased the relative abundance of Bacteroidota, Muribaculaceae_unclassified, Clostridiales_unclassified, and Lachnospiraceae_NK4A136_group, and decreased the relative abundance of Firmicutes, Proteobacteria, and Escherichia-Shigella, which led to a lower Firmicutes/Bacteroidota ratio. Additionally, fucoidan treatment enhanced autophagy, as evidenced by upregulated protein expressions of BECLIN1, ATG5, ATG7, and an increased microtubule-associated-proteinlight-chain-3-II/microtubule-associated-proteinlight-chain-3-I ratio. Our findings corroborated the ameliorating effects of fucoidan intervention on DSS-induced UC through autophagy activation, reorganization of gut microbiota, and fortification of the intestinal barrier. This lends support to the therapeutic potential of fucoidan as a natural bioactive ingredient for future UC treatments in humans.

TFEB SUMOylation in macrophages accelerates atherosclerosis by promoting the formation of foam cells through inhibiting lysosomal activity

Atherosclerosis (AS) is a serious cardiovascular disease. One of its hallmarks is hyperlipidemia. Inhibiting the formation of macrophage foam cells is critical for alleviating AS. Transcription factor EB (TFEB) can limit the formation of macrophage foam cells by upregulating lysosomal activity. We examined whether TFEB SUMOylation is involved in this progress during AS. In this study, we investigated the role of TFEB SUMOylation in macrophages in AS using TFEB SUMOylation deficiency Ldlr-/- (TFEB-KR: Ldlr-/-) transgenic mice and TFEB-KR bone marrow-derived macrophages. We observed that TFEB-KR: Ldlr-/- atherosclerotic mice had thinner plaques and macrophages with higher lysosomal activity when compared to WT: Ldlr-/- mice. TFEB SUMOylation in macrophages decreased after oxidized low-density lipoprotein (OxLDL) treatment in vitro. Compared with wild type macrophages, TFEB-KR macrophages exhibited less lipid deposition after OxLDL treatment. Our study demonstrated that in AS, deSUMOylation of TFEB could inhibit the formation of macrophage foam cells through enhancing lysosomal biogenesis and autophagy, further reducing the accumulation of lipids in macrophages, and ultimately alleviating the development of AS. Thus, TFEB SUMOylation can be a switch to modulate macrophage foam cells formation and used as a potential target for AS therapy.

Current progress in the hypoglycemic mechanisms of natural polysaccharides

Unhealthy dietary pattern-induced type 2 diabetes mellitus poses a great threat to human health all over the world. Accumulating evidence has revealed that the pathophysiology of type 2 diabetes mellitus is closely associated with the dysregulation of glucose metabolism and energy metabolism, serious oxidative stress, prolonged endoplasmic reticulum stress, metabolic inflammation and intestinal microbial dysbiosis. Most important of all, insulin resistance and insulin deficiency are two key factors inducing type 2 diabetes mellitus. Nowadays, natural polysaccharides have gained increasing attention owing to their numerous health-promoting functions, such as hypoglycemic, energy-regulating, antioxidant, anti-inflammatory and prebiotic activities. Therefore, natural polysaccharides have been used to alleviate diet-induced type 2 diabetes mellitus. Specifically, this review comprehensively summarizes the underlying hypoglycemic mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates hypoglycemic mechanisms of natural polysaccharides from the perspectives of their regulatory effects on glucose metabolism, insulin resistance and mitochondrial dysfunction.

A versatile modification strategy for functional non-glutaraldehyde cross-linked bioprosthetic heart valves with enhanced anticoagulant, anticalcification and endothelialization properties

Valvular heart disease is a major threat to human health and transcatheter heart valve replacement (THVR) has emerged as the primary treatment option for severe heart valve disease. Bioprosthetic heart valves (BHVs) with superior hemodynamic performance and compressibility have become the first choice for THVR, and more BHVs have been requested for clinical use in recent years. However, several drawbacks remain for the commercial BHVs cross-linked by glutaraldehyde, including calcification, thrombin, poor biocompatibility and difficulty in endothelialization, which would further reduce the BHVs' lifetime. This study developed a dual-functional non-glutaraldehyde crosslinking reagent OX-VI, which can provide BHV materials with reactive double bonds (CC) for further bio-function modification in addition to the crosslinking function. BHV material PBAF@OX-PP was developed from OX-VI treated porcine pericardium (PP) after the polymerization with 4-vinylbenzene boronic acid and the subsequent modification of poly (vinyl alcohol) and fucoidan. Based on the functional anti-coagulation and endothelialization strategy and dual-functional crosslinking reagent, PBAF@OX-PP has better anti-coagulation and anti-calcification properties, higher biocompatibility, and improved endothelial cells proliferation when compared to Glut-treated PP, as well as the satisfactory mechanical properties and enhanced resistance effect to enzymatic degradation, making it a promising candidate in the clinical application of BHVs. STATEMENT OF SIGNIFICANCE: Transcatheter heart valve replacement (THVR) has become the main solution for severe valvular heart disease. However, bioprosthetic heart valves (BHVs) used in THVR exhibit fatal drawbacks such as calcification, thrombin and difficulty for endothelialization, which are due to the glutaraldehyde crosslinking, resulting in a limited lifetime to 10-15 years. A new non-glutaraldehyde cross-linker OX-VI has been designed, which can not only show great crosslinking ability but also offer the BHVs with reactive double bonds (CC) for further bio-function modification. Based on the dual-functional crosslinking reagent OX-VI, a versatile modification strategy was developed and the BHV material (PBAF@OX-PP) has been developed and shows significantly enhanced anticoagulant, anti-calcification and endothelialization properties, making it a promising candidate in the clinical application of BHVs.

Anti-inflammatory properties of antiangiogenic fucoidan in retinal pigment epithelium cells

Age-related macular degeneration (AMD) is a multifactorial disease in which angiogenesis, oxidative stress and inflammation are important contributing factors. In this study, we investigated the anti-inflammatory effects of a fucoidan from the brown algae Fucus vesiculosus (FV) in primary porcine RPE cells. Inflammation was induced by lipopolysaccharide (LPS), polyinosinic:polycytidylic acid (Poly I:C), Pam2CSK4 (Pam), or tumor necrosis factor alpha (TNF-α). Cell viability was tested with thiazolyl blue tetrazolium bromide (MTT) test, barrier function by measuring transepithelial electric resistance (TEER), interleukin 6 (IL-6) and interleukin 8 (IL-8) secretion in ELISA, retinal pigment epithelium-specific 65 kDa protein (RPE65) and protectin (CD59) expression in Western blot, gene expression with quantitative polymerase chain reaction (qPCR) (IL6, IL8, MERTK, PIK3CA), and phagocytotic activity in a microscopic assay. FV fucoidan did not influence RPE cell viability. FV fucoidan reduced the Poly I:C proinflammatory cytokine secretion of IL-6 and IL-8. In addition, it decreased the expression of IL-6 and IL-8 in RT-PCR. LPS and TNF-α reduced the expression of CD59 in Western blot, this reduction was lost under FV fucoidan treatment. Also, LPS and TNF-α reduced the expression of visual cycle protein RPE65, this reduction was again lost under FV fucoidan treatment. Furthermore, the significant reduction of barrier function after Poly I:C stimulation is ameliorated by FV fucoidan. Concerning phagocytosis, however, the inflammation-induced reduction was not improved by FV fucoidan. FV and proinflammatory milieu did not relevantly influence phagocytosis relevant gene expression either. In conclusion, we show that fucoidan from FV can reduce proinflammatory stimulation in RPE induced by toll-like receptor 3 (TLR-3) activation and is of high interest as a potential compound for early AMD treatment.

TFEB coordinates autophagy and pyroptosis as hepatotoxicity responses to ZnO nanoparticles

Zinc oxide nanoparticles (ZnO NPs) have drawn serious concerns about their biotoxicity due to their extensive applications in biological medicine, clinical therapeutic, daily chemical production, food and agricultural additives. In our present study, we clarified hepatotoxic mechanism of ZnO NPs through investigating the crosstalk between autophagy and pyroptosis, a remaining enigma in hepatocyte stimulated by ZnO NPs. Based on the effects of autophagy intervention by Rapamycin (Rap) and 3-Methyladenine (3-MA), and the observation of pyroptosis morphology and related indexes, the autophagy and pyroptosis simultaneously initiated by ZnO NPs were interrelated and the autophagy characterized by autophagosome production and increased expression of autophagy proteins was identified as a protective response of ZnO NPs against pyroptosis. According to the analysis of protein expression and fluorescence localization, the NLRP3 inflammasome assemble and the classical Caspase-1/GSDMD-dependent pyroptosis induced by ZnO NPs was modulated by autophagy. In this process, the adjustment of TFEB expression and nuclear translocation by gene knockout and gene overexpression, further altered the tendency of ZnO NPs-induced pyroptosis via the regulation of autophagy and lysosomal biogenesis. The knockout of TFEB gene exacerbated the pyroptosis via autophagy elimination and lysosome inhibition. While the alleviation of NLRP3 generation and pyroptosis activation was observed after treatment of TFEB gene overexpression. Additionally, the siRNA interference confirmed that TRAF-6 was involved in the TFEB-mediated global regulation of autophagy-lysosome-pyroptosis in response to ZnO NPs. Accordingly, pyroptosis induced by ZnO NPs in hepatocyte could be significantly avoided by TFEB-regulated autophagy and lysosome, further providing new insights for the risk assessment and therapeutic strategy.

Bioactive polysaccharides and their potential health benefits in reducing the risks of atherosclerosis: A review

Atherosclerosis is a kind of lipid-driven chronic inflammatory disease of arteries and is the principal pathological basis of life-threatening cardiovascular disease events, such as strokes and heart attacks. Clinically, statins are the most commonly prescribed drugs for the treatment of atherosclerosis, but prolonged use of these drugs exhibit many adverse reactions and have limited efficacy. Polysaccharides are important natural biomacromolecules widely existing in plants, animals, microorganisms and algae. They have drawn considerable attention worldwide due to their multiple healthy functions, along with their non-toxic property. Importantly, a growing number of studies have demonstrated that bioactive polysaccharides exhibit prominent efficiency in controlling atherosclerotic risk factors like hyperlipemia, hypertension, oxidative stress, and inflammation. In recent decades, various bioactive polysaccharides with different structural features and anti-atherosclerotic potential from natural sources have been isolated, purified, and characterized. The aim of this review is to focus on the research progress of natural polysaccharides in reducing the risks of atherosclerosis based on evidence of in vitro and in vivo studies from 1966 to 2022. PRACTICAL APPLICATIONS: In the future, it is still necessary to strengthen the research on the development and mechanism of polysaccharides with anti-atherosclerotic potential. These anti-atherosclerotic polysaccharides with different structural characteristics and physiochemical properties from different sources will constitute a huge source of materials for future applications, especially in functional foods and drugs. The information summarized here may serve as useful reference materials for further investigation, production, and application of these polysaccharides in functional foods and therapeutic agents.

Application of fucoidan as treatment for cardiovascular and cerebrovascular diseases

Fucoidan is a marine polysaccharide. In recent years, fucoidan has attracted wide-scale attention from the pharmaceutical industries due to its diverse biological activities such as lipid-lowering, anti-atherosclerosis, and anticoagulation. This review clarifies the pharmacological effects of fucoidan in the treatment of human cardiovascular and cerebrovascular diseases. Fucoidan exerts a hypolipidemic effect by increasing the reverse transport of cholesterol, inhibiting lipid synthesis, reducing lipid accumulation, and increasing lipid metabolism. Inflammation, anti-oxidation, and so on have a regulatory effect in the process of atherosclerosis endothelial cells, macrophages, smooth muscle cells, and so on; fucoidan can not only prevent thrombosis through anticoagulation and regulate platelet activation, but also promote the dissolution of formed thrombi. Fucoidan has a neuroprotective effect, and also has a positive effect on the prognosis of the cardiovascular and cerebrovascular. The prospects of applying fucoidan in cardio-cerebrovascular diseases are reviewed to provide some theoretical bases and inspirations for its full-scale development and utilization.

Defining Endocytic Pathways of Fucoidan-Coated PIBCA Nanoparticles from the Design of their Surface Architecture

Purpose

This work investigated the endocytic pathways taken by poly(isobutylcyanoacrylate) (PIBCA) nanoparticles differing in their surface composition and architecture, assuming that this might determine their efficiency of intracellular drug delivery.

Methods

Nanoparticles (A0, A25, A100, R0, R25 ) were prepared by anionic or redox radical emulsion polymerization using mixtures of dextran and fucoidan (0, 25, 100 % in fucoidan). Cell uptake was evaluated by incubating J774A.1 macrophages with nanoparticles. Endocytic pathways were studied by incubating cells with endocytic pathway inhibitors (chlorpromazine, genistein, cytochalasin D, methyl-ß-cyclodextrin and nocodazole) and nanoparticle uptake was evaluated by flow cytometry and confocal microscopy.

Results

The fucoidan-coated PIBCA nanoparticles A₂₅ were internalized 3-fold more efficiently than R₂₅ due to the different architecture of the fucoidan chains presented on the surface. Different fucoidan density and architecture led to different internalization pathway preferred by the cells. Large A₁₀₀ nanoparticles with surface was covered with fucoidan chains in a loop and train configuration were internalized the most efficiently, 47-fold compared with A₀, and 3-fold compared with R₀ and R₂₅ through non-endocytic energy-independent pathways and reached the cell cytoplasm.

Conclusion

Internalization pathways of PIBCA nanoparticles by J774A.1 macrophages could be determined by nanoparticle fucoidan surface composition and architecture. In turn, this influenced the extent of internalization and localization of accumulated nanoparticles within cells. The results are of interest for rationalizing the design of nanoparticles for potential cytoplamic drug delivery by controlling the nature of the nanoparticle surface.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-022-03202-4.

Sulfated glucuronomannan hexasaccharide G6S1 enhanced lipolysis and lipophagy via PPARα pathway

Nonalcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome, ranging from benign steatosis to severe non-alcoholic steatohepatitis. Recently, it has been found that lipophagy plays a pivotal role in lipid turnover, which can alleviate NAFLD in hepatocytes. In this study, we found that a highly sulfated glucuronomannan hexamer G6S1 has the ability to enhance lipophagy. When treated with G6S1, the number and the size of lipid droplet (LD) decreased significantly on hepatocytes AML12 cells. Western blot results showed that the expressions of the lipolysis-related proteins increased, while the expressions of proteins that is responsible for lipid transportation and synthesis exhibited no significant change. Immunofluorescence assay and electron microscopy results showed an increase of autophagy related protein expression level and lysosome number in hepatocytes treated with G6S1, suggesting that G6S1 could also promote lipophagy. A significant increase of peroxisome proliferator-activated receptor alpha (PPARα) expression level was detected in G6S1 treated cells, suggesting that G6S1 may promote autophagy via enhancing the expression of PPARα. In addition, these effects could be inhibited after treatment with autophagy inhibitor 3-methyladenine (3-MA) and PPARα inhibitor MK-886. These findings indicate that G6S1 can promote lipophagy via enhanced PPARα expression and can result in a slowdown of lipids accumulation.

Caffeine Inhibits Activation of the NLRP3 Inflammasome via Autophagy to Attenuate Microglia-Mediated Neuroinflammation in Experimental Autoimmune Encephalomyelitis

The activation of microglia is an important cause of central nervous system (CNS) inflammatory cell infiltration and inflammatory demyelination in experimental autoimmune encephalomyelitis (EAE). Furthermore, the proinflammatory response induced by the NLR family pyrin domain containing 3 (NLRP3) inflammasome can be amplified in microglia after NLRP3 inflammasome activation. Autophagy is closely related to the inflammatory response. Caffeine exerts anti-inflammatory and autophagy-stimulating effects, but the specific mechanism remains unclear. This study examined the mechanism underlying the anti-inflammatory effect of caffeine on EAE. In this study, C57BL/6 mice were immunized to induce EAE and treated with caffeine to observe its effect on prognosis. The effects of caffeine on autophagy and inflammation were also analysed in mouse primary microglia (PM) and the BV2 cell line. The data demonstrated that caffeine reduced the clinical score, the infiltration of inflammatory cells, the demyelination level, and the activation of microglia in EAE mice. Furthermore, caffeine increased the LC3-II/LC3-I levels and decreased the NLRP3 and P62 levels in EAE mice, whereas the autophagy inhibitor 3-methylamine (3-MA) blocked these effects. In vitro, caffeine promoted autophagy by suppressing the mechanistic target of rapamycin (mTOR) pathway and inhibited activation of the NLRP3 inflammasome. However, autophagy-related gene 5 (ATG5)-specific siRNA abolished the anti-inflammatory effect of caffeine treatment in PM and BV2 cells. Taken together, these data suggest that caffeine exerts a newly discovered effect on EAE by reducing NLRP3 inflammasome activation via the induction of autophagy in microglia.