Chitosan oligosaccharides block LPS-induced O-GlcNAcylation of NF-κB and endothelial inflammatory response

Enhancing gut barrier integrity: Upregulation of tight junction proteins by chitosan oligosaccharide through the ERK1/2 signaling pathway

OBJECTIVES

This study aimed to explore the protective mechanism of chitosan oligosaccharide (COS) against lipopolysaccharide (LPS)-induced inflammatory responses in IEC-6 cells and dextran sodium sulfate (DSS)-induced colitis in mice.

METHODS

The cell inflammation model was constructed by LPS in vitro and enteritis model by DSS in vivo.

RESULTS

Following LPS exposure, IEC-6 cell proliferation significantly decreased, epithelial cell integrity was compromised, and TNF-α and IL-1β levels were increased. However, COS pretreatment reversed these changes. In vivo, DSS-treated mice exhibited evident pathological alterations, including heightened inflammatory levels and significantly decreased expression of tight junction proteins and critical proteins in the Mitogen activated proteins kinase signaling pathway. Nevertheless, COS administration notably reduced inflammatory levels and increased the expression of tight junction proteins and key proteins in the Mitogen activated proteins kinase signaling pathway.

CONCLUSIONS

Our findings suggest that COS safeguards gut barrier integrity by upregulating tight junction proteins through the ERK1/2 signaling pathway. Therefore, COS has emerged as a promising candidate for novel drug interventions against inflammatory bowel disease.

Chitosan oligosaccharides alleviate macrophage pyroptosis and protect sepsis mice via activating the Nrf2/GPX4 pathway

In the process of sepsis, excessive occurrence of pyroptosis, a form of programmed cell death acting as a defense mechanism against pathogens, can disrupt immune responses, thus leading to tissue damage and organ dysfunction. Chitosan oligosaccharide (COS), derived from chitosan degradation, has demonstrated diverse beneficial effects. However, its impact on sepsis-induced pyroptosis remains unexplored. In the present study, ATP/LPS was utilized to induce canonical-pyroptosis in THP-1 cells, while bacterial outer membrane vesicles (OMV) were employed to trigger non-canonical pyroptosis in RAW264.7 cells. Our results revealed a dose-dependent effect of COS on both types of pyroptosis. This was evidenced by a reduction in the expression of pro-inflammatory cytokines, as well as crucial regulatory proteins involved in pyroptosis. In addition, COS inhibited the cleavage of caspase-1 and GSDMD, and reduced ASC oligomerization. The underlying mechanism revealed that COS acts an antioxidant, reducing the release of pyroptosis-induced ROS and malondialdehyde (MDA) by upregulation the expression and promoting the nuclear translocation of nuclear factor erythroid-2-related factor 2 (Nrf2), which led to an elevation of glutathione peroxidase 4 (GPX4) and superoxide dismutase (SOD). Notably, the actions of COS were completely reversed by the Nrf2 inhibitor. Consequently, COS intervention increased the survival rate of sepsis.

O-GlcNAcylation: a pro-survival response to acute stress in the cardiovascular and central nervous systems

O-GlcNAcylation is a unique monosaccharide modification that is ubiquitously present in numerous nucleoplasmic and mitochondrial proteins. The hexosamine biosynthesis pathway (HBP), which is a key branch of glycolysis, provides the unique sugar donor UDP-GlcNAc for the O-GlcNAc modification. Thus, HBP/O-GlcNAcylation can act as a nutrient sensor to perceive changes in nutrient levels and trigger O-GlcNAc modifications of functional proteins in cellular (patho-)physiology, thereby regulating diverse metabolic processes. An imbalance in O-GlcNAcylation has been shown to be a pathogenic contributor to dysfunction in metabolic diseases, including type 2 diabetes, cancer, and neurodegeneration. However, under acute stress conditions, protein O-GlcNAc modification exhibits rapid and transient upregulation, which is strongly correlated with stress tolerance and cell survival. In this context, we discuss the metabolic, pharmacological and genetic modulation of HBP/O-GlcNAc modification in the biological system, the beneficial role of O-GlcNAcylation in regulating stress tolerance for cardioprotection, and neuroprotection, which is a novel and rapidly growing field. Current evidence suggests that transient activation of the O-GlcNAc modification represents a potent pro-survival signalling pathway and may provide a promising strategy for stress-related disorder therapy.

Impacts of chitosan and its nanoformulations on the metabolic syndromes: a review

A significant public health issue worldwide is metabolic syndrome, a cluster of metabolic illnesses that comprises insulin resistance, obesity, dyslipidemia, hyperglycemia, and hypertension. The creation of natural treatments and preventions for metabolic syndrome is crucial. Chitosan, along with its nanoformulations, is an oligomer of chitin, the second-most prevalent polymer in nature, which is created via deacetylation. Due to its plentiful biological actions in recent years, chitosan and its nanoformulations have drawn much interest. Recently, the chitosan nanoparticle-based delivery of CRISPR-Cas9 has been applied in treating metabolic syndromes. The benefits of chitosan and its nanoformulations on insulin resistance, obesity, diabetes mellitus, dyslipidemia, hyperglycemia, and hypertension will be outlined in the present review, highlighting potential mechanisms for the avoidance and medication of the metabolic syndromes by chitosan and its nanoformulations.

Chitosan as excellent bio-macromolecule with myriad of anti-activities in biomedical applications - A review

The aim of the study is to explore the myriad of anti-activities of chitosan - deacylated derivative of chitin in biomedical applications. Chitosan consists of reactive residual amino groups, which can be modified chemically to obtain wide range of derivatives. These derivatives exhibit the controlled physicochemical characteristics, which in turn improve its functional properties. Such derivatives find numerous applications in the field of biomedical science, agriculture, tissue engineering, bone regeneration and environmental science. This study presents a comprehensive overview of the multifarious anti-activities of chitosan and its derivatives in the field of biomedical science including anti-microbial, antioxidant, anti-tumor, anti-HIV, anti-fungal, anti- inflammatory, anti-Alzheimer's, anti-hypertensive and anti-diabetic activity. It briefly details these anti-activities with respect to its mode of action, pharmacological effects and potential applications. It also presents the overview of current research exploring novel derivatives of chitosan and its anti- activities in the recent past. Finally, the review projects the prospective potential of chitosan and its derivatives and expects to encourage the readers to develop new drug delivery systems based on such chitosan derivatives and explore its applications in biomedical science for benefit of mankind.

O-GlcNAcylation: cellular physiology and therapeutic target for human diseases

O-linked-β-N-acetylglucosamine (O-GlcNAcylation) is a distinctive posttranslational protein modification involving the coordinated action of O-GlcNAc transferase and O-GlcNAcase, primarily targeting serine or threonine residues in various proteins. This modification impacts protein functionality, influencing stability, protein-protein interactions, and localization. Its interaction with other modifications such as phosphorylation and ubiquitination is becoming increasingly evident. Dysregulation of O-GlcNAcylation is associated with numerous human diseases, including diabetes, nervous system degeneration, and cancers. This review extensively explores the regulatory mechanisms of O-GlcNAcylation, its effects on cellular physiology, and its role in the pathogenesis of diseases. It examines the implications of aberrant O-GlcNAcylation in diabetes and tumorigenesis, highlighting novel insights into its potential role in cardiovascular diseases. The review also discusses the interplay of O-GlcNAcylation with other protein modifications and its impact on cell growth and metabolism. By synthesizing current research, this review elucidates the multifaceted roles of O-GlcNAcylation, providing a comprehensive reference for future studies. It underscores the potential of targeting the O-GlcNAcylation cycle in developing novel therapeutic strategies for various pathologies.

Pleiotropic Modulation of Chitooligosaccharides on Inflammatory Signaling in LPS-Induced Macrophages

Chitooligosaccharide (COS) is a green and non-toxic cationic carbohydrate that has attracted wide attention in recent years due to its anti-inflammatory activity. However, the anti-inflammatory mechanism of COS remains unclear. In this study, RNA-seq was used to investigate the integrated response of COS to LPS-induced damage in macrophages. The results showed that the experimental group with COS had 2570 genes with significant differences compared to the model group, and that these genes were more enriched in inflammatory and immune pathways. The KEGG results showed that COS induces the pleiotropic modulation of classical inflammatory pathways, such as the Toll-like receptor signaling pathway, NF-κB, MAPK, etc. Based on the RNA-seq data and the RT-qPCR, as well as the WB validation, COS can significantly upregulate the expression of membrane receptors, such as Tlr4, Tlr5, and MR, and significantly inhibits the phosphorylation of several important proteins, such as IκB and JNK. Overall, this study offers deep insights into the anti-inflammatory mechanism and lays the foundation for the early application of COS as an anti-inflammatory drug.

Anti-inflammatory activity of Echinosophora koreensis nakai root extract in lipopolysaccharides-stimulated RAW 264.7 cells and carrageenan-induced mouse paw edema model

ETHNOPHARMACOLOGICAL RELEVANCE

Echinosophora koreensis Nakai is an endemic plant species distributed in a limited area within the Korean province of Gangwon, including the Yanggu-gun, Inje-gun, Cheorwon-gun, Chuncheon-si, and Hongcheon-gun counties. It is used in traditional medicine to treat various disorders, such as fever, skin diseases, diuresis, and neuralgia.

MATERIALS AND METHODS

This study demonstrated the effects of E. koreensis Nakai root extract (EKRE) on lipopolysaccharide (LPS)-induced inflammatory responses in vitro and in vivo. Cell viability was assessed through a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Nitric oxide (NO) production was measured using Griess reagent. Interleukin (IL)-6 and tumor necrosis factor (TNF) levels were assessed using enzyme-linked immunosorbent assays. Inducible nitric oxide synthase (iNOS), nuclear factor kappa-B (NF-κB), and mitogen-activated protein kinase (MAPK) expression were assessed using Western blot analysis. To examine the effects of EKRE in vivo, it was administered orally at doses of 50 or 200 mg/kg for 3 days in mice. Edema in the paws was induced through λ-carrageenan injection and measured hourly for up to 5 h using calipers.

RESULTS

EKRE markedly suppressed LPS-generated NO, IL-6, and iNOS production in RAW 264.7 cells. Moreover, it suppressed the activation of the NF-κB and MAPK in LPS-stimulated cells. Furthermore, EKRE significantly inhibited carrageenan-induced edema in mouse paws. There were no significant differences in IL-6 and TNF production in paw tissue harvested from mice, but levels decreased at high EKRE concentrations (200 mg/kg).

CONCLUSION

The results of this study provided validation for EKRE-induced inhibition of inflammatory responses in vitro and in vivo. This research suggested that EKRE is a promising treatment for inflammatory disorders.

The role of O-GlcNAcylation in innate immunity and inflammation

O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) is a highly dynamic and widespread post-translational modification (PTM) that regulates the activity, subcellular localization, and stability of target proteins. O-GlcNAcylation is a reversible PTM controlled by two cycling enzymes: O-linked N-acetylglucosamine transferase and O-GlcNAcase. Emerging evidence indicates that O-GlcNAcylation plays critical roles in innate immunity, inflammatory signaling, and cancer development. O-GlcNAcylation usually occurs on serine/threonine residues, where it interacts with other PTMs, such as phosphorylation. Thus, it likely has a broad regulatory scope. This review discusses the recent research advances regarding the regulatory roles of O-GlcNAcylation in innate immunity and inflammation. A more comprehensive understanding of O-GlcNAcylation could help to optimize therapeutic strategies regarding inflammatory diseases and cancer.

Severe COVID-19-A Review of Suggested Mechanisms Based on the Role of Extracellular Matrix Stiffness

The severity of COVID-19 commonly depends on age-related tissue stiffness. The aim was to review publications that explain the effect of microenvironmental extracellular matrix stiffness on cellular processes. Platelets and endothelial cells are mechanosensitive. Increased tissue stiffness can trigger cytokine storm with the upregulated expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha and interleukin IL-6, and tissue integrity disruption, leading to enhanced virus entry and disease severity. Increased tissue stiffness in critically ill COVID-19 patients triggers platelet activation and initiates plague formation and thrombosis development. Cholesterol content in cell membrane increases with aging and further enhances tissue stiffness. Membrane cholesterol depletion decreases virus entry to host cells. Membrane cholesterol lowering drugs, such as statins or novel chitosan derivatives, have to be further developed for application in COVID-19 treatment. Statins are also known to decrease arterial stiffness mitigating cardiovascular diseases. Sulfated chitosan derivatives can be further developed for potential use in future as anticoagulants in prevention of severe COVID-19. Anti-TNF-α therapies as well as destiffening therapies have been suggested to combat severe COVID-19. The inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cells pathway must be considered as a therapeutic target in the treatment of severe COVID-19 patients. The activation of mechanosensitive platelets by higher matrix stiffness increases their adhesion and the risk of thrombus formation, thus enhancing the severity of COVID-19.

The Use of Chitosan Nanoparticles for Delivery of CpG ODN in Treatment of Allergic Balb/C Mice

Background

This study aims to prepare high stability chitosan nanoparticles (CNP) and examine the ability of CNP in CpG-ODN delivery when treating allergic mice model.

Methods

Preparation and characterization of CNP were performed by ionic gelation, dynamic light scattering, and zeta sizer. The CNP cytotoxicity and activation ability of CpG ODN delivered with CNP were tested using a cell counting kit-8 and Quanti blue method. Allergic mice were injected intraperitoneal with 10 ug ovalbumin on day 0 and 7, and then treated with intranasal CpG ODN/CpG ODN, delivered with CNP/CNP, on the third week three times per week for three weeks. The ELISA method measured cytokine and IgE profiles in the allergic mice's plasma and spleen.

Results

CNP results have sizes 27.73 nm±3.67 dan 188.23 nm±53.47, spherical in shape and non-toxic, and did not alter the NF-κB activation of CpG ODN in RAW-blue cells. The application of CpG ODN delivered by chitosan nanoparticles shows no statistical difference between groups of IFN-γ, IL-10, and IL-13 in Balb/c mice's plasma and spleen, in contrast with IgE level.

Conclusions

The results showed that using chitosan nanoparticles as a delivery system for CpG ODN has the potency to safely CpG ODN efficacy.

Potential Medical Applications of Chitooligosaccharides

Chitooligosaccharides, also known as chitosan oligomers or chitooligomers, are made up of chitosan with a degree of polymerization (DP) that is less than 20 and an average molecular weight (MW) that is lower than 3.9 kDa. COS can be produced through enzymatic conversions using chitinases, physical and chemical applications, or a combination of these strategies. COS is of significant interest for pharmacological and medical applications due to its increased water solubility and non-toxicity, with a wide range of bioactivities, including antibacterial, anti-inflammatory, anti-obesity, neuroprotective, anticancer, and antioxidant effects. This review aims to outline the recent advances and potential applications of COS in various diseases and conditions based on the available literature, mainly from preclinical research. The prospects of further in vivo studies and translational research on COS in the medical field are highlighted.

The Effect of N-Acetylation on the Anti-Inflammatory Activity of Chitooligosaccharides and Its Potential for Relieving Endotoxemia

Endotoxemia is mainly caused by a massive burst of inflammatory cytokines as a result of lipopolysaccharide (LPS) invasion. Chitooligosaccharides (COS) is expected to be a potential drug for relieving endotoxemia due to its anti-inflammatory properties. However, the structural parameters of COS are often ambiguous, and the effect of degree of acetylation (DA) of COS on its anti-inflammatory remains unknown. In this study, four COSs with different DAs (0%, 12%, 50% and 85%) and the same oligomers distribution were successfully obtained. Their structures were confirmed by ¹H NMR and MS analysis. Then, the effect of DA on the anti-inflammatory activity and relieving endotoxemia potential of COS was researched. The results revealed that COS with a DA of 12% had better anti-inflammatory activity than COSs with other DAs, mainly in inhibiting LPS-induced inflammatory cytokines burst, down-regulating its mRNA expression and reducing phosphorylation of IκBα. Furthermore, this COS showed an obviously protective effect on endotoxemia mice, such as inhibiting the increase in inflammatory cytokines and transaminases, alleviating the injury of liver and intestinal tissue. This study explored the effect of DA on the anti-inflammatory activity of COS for the first time and lays the foundation for the development of COS as an anti-inflammatory drug against endotoxemia.

Chitosan and Chitooligosaccharide: The Promising Non-Plant-Derived Prebiotics with Multiple Biological Activities

Biodegradable chitin is the second-most abundant natural polysaccharide, widely existing in the exoskeletons of crabs, shrimps, insects, and the cell walls of fungi. Chitosan and chitooligosaccharide (COS, also named chitosan oligosaccharide) are the two most important deacetylated derivatives of chitin. Compared with chitin, chitosan and COS not only have more satisfactory physicochemical properties but also exhibit additional biological activities, which cause them to be widely applied in the fields of food, medicine, and agriculture. Additionally, due to their significant ability to improve gut microbiota, chitosan and COS are deemed prospective prebiotics. Here, we introduced the production, physicochemical properties, applications, and pharmacokinetic characteristics of chitosan and COS. Furthermore, we summarized the latest research on their antioxidant, anti-inflammatory, and antimicrobial activities. Research progress on the prebiotic functions of chitosan and COS is particularly reviewed. We creatively analyzed and discussed the mechanisms and correlations underlying these activities of chitosan and COS and their physicochemical properties. Our work enriched people's understanding of these non-plant-derived prebiotics. Based on this review, the future directions of research on chitosan and COS are explored. Collectively, optimizing the production technology of chitin derivatives and enriching understanding of their biological functions will shed more light on their capability to improve human health.

The interaction of O-GlcNAc-modified NLRX1 and IKK-α modulates IL-1β expression in M1 macrophages

NOD-like receptor (NLR)X1 (NLRX1) is a negative regulator of inflammation by inhibiting nuclear factor-κB (NF-κB) signaling and downstream pro-inflammatory factors. However, its post-translational modification and how it participates in regulating the inflammatory responses in macrophages are still unclear. Here, we found that NLRX1 was modified with O-linked N-acetylglucosamine (O-GlcNAc). The interaction and co-localization between NLRX1 and O-GlcNAc transferase (OGT) was validated by co-immunoprecipitation and confocal microscopy analysis, and the nucleotide-binding domain (NBD) region of NLRX1 was required for its interaction with OGT. NLRX1 protein increased significantly after treatment with a high dose of OGT inhibitor OSMI-1. Elevated O-GlcNAcylation level promoted NLRX1 ubiquitination and decreased NLRX1 stability proved by ubiquitination and cycloheximide (CHX) chase experiments, and enhanced the interaction between NLRX1 and inhibitor of nuclear factor kappaB kinase-α (IKK-α), thus reducing the expression of inflammatory cytokine IL-1β in M1 macrophages. Together, our results indicate that the interaction between NLRX1 and O-GlcNAcylation coordinates and modulates the inflammatory process in macrophages.

Targeting Protein O-GlcNAcylation, a Link between Type 2 Diabetes Mellitus and Inflammatory Disease

Unresolved hyperglycaemia, a hallmark of type 2 diabetes mellitus (T2DM), is a well characterised manifestation of altered fuel homeostasis and our understanding of its role in the pathologic activation of the inflammatory system continues to grow. Metabolic disorders like T2DM trigger changes in the regulation of key cellular processes such as cell trafficking and proliferation, and manifest as chronic inflammatory disorders with severe long-term consequences. Activation of inflammatory pathways has recently emerged as a critical link between T2DM and inflammation. A substantial body of evidence has suggested that this is due in part to increased flux through the hexosamine biosynthetic pathway (HBP). The HBP, a unique nutrient-sensing metabolic pathway, produces the activated amino sugar UDP-GlcNAc which is a critical substrate for protein O-GlcNAcylation, a dynamic, reversible post-translational glycosylation of serine and threonine residues in target proteins. Protein O-GlcNAcylation impacts a range of cellular processes, including inflammation, metabolism, trafficking, and cytoskeletal organisation. As increased HBP flux culminates in increased protein O-GlcNAcylation, we propose that targeting O-GlcNAcylation may be a viable therapeutic strategy for the prevention and management of glucose-dependent pathologies with inflammatory components.

An Overview of Glycosylation and its Impact on Cardiovascular Health and Disease

The cardiovascular system is a complex and well-organized system in which glycosylation plays a vital role. The heart and vascular wall cells are constituted by an array of specific receptors; most of them are N- glycosylated and mucin-type O-glycosylated. There are also intracellular signaling pathways regulated by different post-translational modifications, including O-GlcNAcylation, which promote adequate responses to extracellular stimuli and signaling transduction. Herein, we provide an overview of N-glycosylation and O-glycosylation, including O-GlcNAcylation, and their role at different levels such as reception of signal, signal transduction, and exogenous molecules or agonists, which stimulate the heart and vascular wall cells with effects in different conditions, like the physiological status, ischemia/reperfusion, exercise, or during low-grade inflammation in diabetes and aging. Furthermore, mutations of glycosyltransferases and receptors are associated with development of cardiovascular diseases. The knowledge on glycosylation and its effects could be considered biochemical markers and might be useful as a therapeutic tool to control cardiovascular diseases.

O-GlcNAcylation in Ventral Tegmental Area Dopaminergic Neurons Regulates Motor Learning and the Response to Natural Reward

Protein O-GlcNAcylation is a post-translational modification that links environmental stimuli with changes in intracellular signal pathways, and its disturbance has been found in neurodegenerative diseases and metabolic disorders. However, its role in the mesolimbic dopamine (DA) system, especially in the ventral tegmental area (VTA), needs to be elucidated. Here, we found that injection of Thiamet G, an O-GlcNAcase (OGA) inhibitor, in the VTA and nucleus accumbens (NAc) of mice, facilitated neuronal O-GlcNAcylation and decreased the operant response to sucrose as well as the latency to fall in rotarod test. Mice with DAergic neuron-specific knockout of O-GlcNAc transferase (OGT) displayed severe metabolic abnormalities and died within 4-8 weeks after birth. Furthermore, mice specifically overexpressing OGT in DAergic neurons in the VTA had learning defects in the operant response to sucrose, and impaired motor learning in the rotarod test. Instead, overexpression of OGT in GABAergic neurons in the VTA had no effect on these behaviors. These results suggest that protein O-GlcNAcylation of DAergic neurons in the VTA plays an important role in regulating the response to natural reward and motor learning in mice.

Caragana rosea Turcz Methanol Extract Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Suppressing the TLR4/NF-κB/IRF3 Signaling Pathways

Caragana rosea Turcz, which belongs to the Leguminosae family, is a small shrub found in Northern and Eastern China that is known to possess anti-inflammatory properties and is used to treat fever, asthma, and cough. However, the underlying molecular mechanisms of its anti-inflammatory effects are unknown. Therefore, we used lipopolysaccharide (LPS) in RAW264.7 macrophages to investigate the molecular mechanisms that underlie the anti-inflammatory activities of a methanol extract of Caragana rosea (Cr-ME). We showed that Cr-ME reduced the production of nitric oxide (NO) and mRNA levels of iNOS, TNF-α, and IL-6 in a concentration-dependent manner. We also found that Cr-ME blocked MyD88- and TBK1-induced NF-κB and IRF3 promoter activity, suggesting that it affects multiple targets. Moreover, Cr-ME reduced the phosphorylation levels of IκBα, IKKα/β and IRF3 in a time-dependent manner and regulated the upstream NF-κB proteins Syk and Src, and the IRF3 protein TBK1. Upon overexpression of Src and TBK1, Cr-ME stimulation attenuated the phosphorylation of the NF-κB subunits p50 and p65 and IRF3 signaling. Together, our results suggest that the anti-inflammatory activity of Cr-ME occurs by inhibiting the NF-κB and IRF3 signaling pathways.

Production and Characterization of Chitooligosaccharides: Evaluation of Acute Toxicity, Healing, and Anti-Inflammatory Actions

The search for promising biomolecules such as chitooligosaccharides (COS) has increased due to the need for healing products that act efficiently, avoiding complications resulting from exacerbated inflammation. Therefore, this study aimed to produce COS in two stages of hydrolysis using chitosanases derived from Bacillus toyonensis. Additionally, this study aimed to structurally characterize the COS via mass spectrometry, to analyze their biocompatibility in acute toxicity models in vivo, to evaluate their healing action in a cell migration model in vitro, to analyze the anti-inflammatory activity in in vivo models of xylol-induced ear edema and zymosan-induced air pouch, and to assess the wound repair action in vivo. The structural characterization process pointed out the presence of hexamers. The in vitro and in vivo biocompatibility of COS was reaffirmed. The COS stimulated the fibroblast migration. In the in vivo inflammatory assays, COS showed an antiedematogenic response and significant reductions in leukocyte migration, cytokine release, and protein exudate. The COS healing effect in vivo was confirmed by the significant wound reduction after seven days of the experiment. These results indicated that the presence of hexamers influences the COS biological properties, which have potential uses in the pharmaceutical field due to their healing and anti-inflammatory action.

The Role of Chitosan Oligosaccharide in Metabolic Syndrome: A Review of Possible Mechanisms

Metabolic syndrome, a cluster of metabolic disorders including central obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension, has become a major public health problem worldwide. It is of great significance to develop natural products to prevent and treat metabolic syndrome. Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin, which is the second most abundant polymer in nature. In recent years, COS has received widespread attention due to its various biological activities. The present review will summarize the evidence from both in vitro and in vivo studies of the beneficial effects of COS on obesity, dyslipidemia, diabetes mellitus, hyperglycemia, and hypertension, and focus attention on possible mechanisms of the prevention and treatment of metabolic syndrome by COS.

Efficient Preparation of Chitooligosaccharide With a Potential Chitosanase Csn-SH and Its Application for Fungi Disease Protection

Chitosanase plays a vital role in bioactive chitooligosaccharide preparation. Here, we characterized and prepared a potential GH46 family chitosanase from Bacillus atrophaeus BSS. The purified recombinant enzyme Csn-SH showed a molecular weight of 27.0 kDa. Csn-SH displayed maximal activity toward chitosan at pH 5.0 and 45°C. Thin-layer chromatography and electrospray ionization–mass spectrometry indicated that Csn-SH mainly hydrolyzed chitosan into (GlcN)₂, (GlcN)₃, and (GlcN)₄ with an endo-type cleavage pattern. Molecular docking analysis demonstrated that Csn-SH cleaved the glycoside bonds between subsites −2 and + 1 of (GlcN)₆. Importantly, the chitosan hydrolysis rate of Csn-SH reached 80.57% within 40 min, which could reduce time and water consumption. The hydrolysates prepared with Csn-SH exhibited a good antifungal activity against Magnaporthe oryzae and Colletotrichum higginsianum. The above results suggested that Csn-SH could be used to produce active chitooligosaccharides efficiently that are biocontrol agents applicable for safe and sustainable agricultural production.

Advances in the preparation and assessment of the biological activities of chitosan oligosaccharides with different structural characteristics

Chitosan oligosaccharides (COSs) are widely used biopolymers that have been studied in relation to a variety of abnormal biological activities in the food and biomedical fields. Since different COS preparation technologies produce COS compounds with different structural characteristics, it has not yet been possible to determine whether one or more chito-oligomers are primarily responsible for the bioactivity of COSs. The inherent biocompatibility, mucosal adhesion and nontoxic nature of COSs are well documented, as is the fact that they are readily absorbed from the intestinal tract, but their structure-activity relationship requires further investigation. This review summarizes the methods used for COS preparation, and the research findings with regard to the antioxidant, anti-inflammatory, anti-obesity, bacteriostatic and antitumour activity of COSs with different structural characteristics. The correlation between the molecular structure and bioactivities of COSs is described, and new insights into their structure-activity relationship are provided.

Bioactive potential of natural biomaterials: identification, retention and assessment of biological properties

Biomaterials have had an increasingly important role in recent decades, in biomedical device design and the development of tissue engineering solutions for cell delivery, drug delivery, device integration, tissue replacement, and more. There is an increasing trend in tissue engineering to use natural substrates, such as macromolecules native to plants and animals to improve the biocompatibility and biodegradability of delivered materials. At the same time, these materials have favourable mechanical properties and often considered to be biologically inert. More importantly, these macromolecules possess innate functions and properties due to their unique chemical composition and structure, which increase their bioactivity and therapeutic potential in a wide range of applications. While much focus has been on integrating these materials into these devices via a spectrum of cross-linking mechanisms, little attention is drawn to residual bioactivity that is often hampered during isolation, purification, and production processes. Herein, we discuss methods of initial material characterisation to determine innate bioactivity, means of material processing including cross-linking, decellularisation, and purification techniques and finally, a biological assessment of retained bioactivity of a final product. This review aims to address considerations for biomaterials design from natural polymers, through the optimisation and preservation of bioactive components that maximise the inherent bioactive potency of the substrate to promote tissue regeneration.

Nrf2 Signaling Pathway in Chemoprotection and Doxorubicin Resistance: Potential Application in Drug Discovery

Doxorubicin (DOX) is extensively applied in cancer therapy due to its efficacy in suppressing cancer progression and inducing apoptosis. After its discovery, this chemotherapeutic agent has been frequently used for cancer therapy, leading to chemoresistance. Due to dose-dependent toxicity, high concentrations of DOX cannot be administered to cancer patients. Therefore, experiments have been directed towards revealing underlying mechanisms responsible for DOX resistance and ameliorating its adverse effects. Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling is activated to increase levels of reactive oxygen species (ROS) in cells to protect them against oxidative stress. It has been reported that Nrf2 activation is associated with drug resistance. In cells exposed to DOX, stimulation of Nrf2 signaling protects cells against cell death. Various upstream mediators regulate Nrf2 in DOX resistance. Strategies, both pharmacological and genetic interventions, have been applied for reversing DOX resistance. However, Nrf2 induction is of importance for alleviating side effects of DOX. Pharmacological agents with naturally occurring compounds as the most common have been used for inducing Nrf2 signaling in DOX amelioration. Furthermore, signaling networks in which Nrf2 is a key player for protection against DOX adverse effects have been revealed and are discussed in the current review.

Chitosan and chitooligosaccharides attenuate soyabean meal-induced intestinal inflammation of turbot (Scophthalmus maximus): possible involvement of NF-кB, activator protein-1 and mitogen-activated protein kinases pathways

An 8-week feeding experiment was conducted to investigate and confront the putative functions of chitosan (CTS) and chitooligosaccharide (COS) in the growth and homoeostasis of distal intestine in juvenile turbots fed diets containing soyabean meal (SBM). Three isolipidic and isonitrogenous diets were formulated by supplemented basal diet (based on a 400 g/kg SBM) with 7·5 g/kg CTS or with 2·0 g/kg COS. Our results indicated that both CTS and COS supplementation could significantly improve (i) the growth performance and feed efficiency ratio; (ii) antioxidant activity driven by metabolic enzymes (i.e. catalase, glutathione reductase, glutathione peroxidase and superoxide dismutase); (iii) glutathione levels; (iv) acid phosphatase and lysozyme activity and (v) IgM content. As a result, these two particular prebiotics were able to significantly attenuate the histological alterations due to local inflammation as well as to decrease the transcriptional levels of proinflammatory cytokines (i.e. IL-1β, IL-8 and TNF-α) and major pathway effectors (i.e. activator protein-1 (AP-1), NF-кB, p38 mitogen-activated protein kinase, c-Jun N-terminal kinase and extracellular regulated kinase). High-throughput sequencing data indicated that dietary CTS and COS could significantly decrease the diversity of intestinal bacteria but elevate the relative abundances of Bacillus, Lactobacillus and Pseudomonas genera. Altogether, these findings suggest that CTS and COS can improve growth of turbot, enhance intestinal immune and anti-oxidant systems and promote the balance of intestinal microbiota. The protective effects, elicited by these two prebiotics, against SBM-induced inflammation could be attributed to their roles in alleviating the overexpression of inflammatory cytokines by possibly down-regulating NF-кB, AP-1 and/or mitogen-activated protein kinases pathways.

Research Advances in Chitosan Oligosaccharides: From Multiple Biological Activities to Clinical Applications

Chitosan oligosaccharides (COS), hydrolysed products of chitosan, are low-molecular weight polymers with a positive charge and good biocompatibility. COS have recently been reported to possess various biological activities, including hypoglycaemic, hypolipidaemic, antioxidantantioxidant, immune regulation, anti-inflammatory, antitumour, antibacterial, and tissue engineering activities, exhibiting extensive application prospects. Currently, the biological processes and mechanisms of COS are attractive topics of study, ranging from the genetic, molecular and protein levels. This article reviews the recent discoveries about COS, especially in metabolic regulation, immune function and tissue repair, providing important insights into their multiple biological activities, medical benefits, and therapeutic mechanisms.

Immunomodulatory Effects of N-Acetyl Chitooligosaccharides on RAW264.7 Macrophages

The ongoing development of new production methods may lead to the commercialization of N-acetyl chitooligosaccharides (NACOS), such as chitosan oligosaccharides (COS). The bioactivity of NACOS, although not well detailed, differs from that of COS, as they have more acetyl groups than COS. We used two enzymatically produced NACOS with different molecular compositions and six NACOS (NACOS1–6) with a single degree of polymerization to verify their immunomodulatory effects on the RAW264.7 macrophage cell line. We aimed to identify any differences between COS and various NACOS with a single degree of polymerization. The results showed that NACOS had similar immune enhancement effects on RAW264.7 cells as COS, including the generation of reactive oxygen species (ROS), phagocytotic activity, and the production of pro-inflammation cytokines (IL-1β, IL-6, and TNF-α). However, unlike COS and lipopolysaccharide (LPS), NACOS1 and NACOS6 significantly inhibited nitric oxide (NO) production. Besides their immune enhancement effects, NACOS also significantly inhibited the LPS-induced RAW264.7 inflammatory response with some differences between various polymerization degrees. We confirmed that the NF-κB pathway is associated with the immunomodulatory effects of NACOS on RAW264.7 cells. This study could inform the application of NACOS with varying different degrees of polymerization in human health.

Resveratrol inhibits LPS-induced inflammation through suppressing the signaling cascades of TLR4-NF-κB/MAPKs/IRF3

Resveratrol (Res) is a natural compound that possesses anti-inflammatory properties. However, the protective molecular mechanisms of Res against lipopolysaccharide (LPS)-induced inflammation have not been fully studied. In the present study, RAW264.7 cells were stimulated with LPS in the presence or absence of Res, and the subsequent modifications to the LPS-induced signaling pathways caused by Res treatment were examined. It was identified that Res decreased the mRNA levels of Toll-like receptor 4 (TLR4), myeloid differentiation primary response protein MyD88, TIR domain-containing adapter molecule 2, which suggested that Res may inhibit the activation of the TLR4 signaling pathway. It suppressed the expression levels of total and phosphorylated TLR4, NF-κB inhibitor, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase, extracellular signal-regulated kinase 1/2 and interferon (IFN) regulatory factor 3 (IRF3) proteins. Following treatment with Res or specific inhibitors, the production of pro-inflammatory mediators including tumor necrosis factor-α, interleukin (IL)-6, IL-8 and IFN-β were decreased and the expression of anti-inflammatory mediator IL-10 was increased. These results suggested that Res may inhibit the signaling cascades of NF-κB, MAPKs and IRF3, which modulate pro-inflammatory cytokines. In conclusion, Res exhibited a therapeutic effect on LPS-induced inflammation through suppression of the TLR4-NF-κB/MAPKs/IRF3 signaling cascades.

Water-separated part of Chloranthus serratus alleviates lipopolysaccharide- induced RAW264.7 cell injury mainly by regulating the MAPK and Nrf2/HO-1 inflammatory pathways

Background

Chloranthus serratus (Chloranthaceae) has been used to treat bruises, rheumatoid and bone pain. However, the anti-inflammatory mechanisms of C. serratus in vitro have not been fully elucidated. The present study aimed to explore the anti-inflammatory activity and potential mechanisms of C. serratus’s separated part of water (CSSPW) in lipopolysaccharide (LPS)-induced RAW264.7 cells.

Methods

The concentrations of CSSPW were optimized by CCK-8 method. Nitric oxide (NO) content was detected by one-step method. The levels of inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA). Gene expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was detected by real-time quantitative PCR (qPCR). Immunofluorescence and DCFH-DA fluorescent probes were used to detect p65 nuclear translocation and reactive oxygen species (ROS) content, respectively. Western blotting was used to assay the protein expression of mitogen-activated protein kinases (MAPK), nuclear factor-kappa B (NF-κB) and nuclear transcription factor E2 related factor 2/haem oxygenase-1 (Nrf2/HO-1) pathways.

Results

The final concentrations of 15 ng/mL, 1.5 μg/mL and 150 μg/mL were selected as low, medium and high doses of CSSPW, respectively. CSSPW treatment significantly reduced the generation of NO, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), prostaglandinE₂ (PGE₂), iNOS mRNA and COX-2 mRNA in response to LPS stimulation. Furthermore, the protein expression of the MAPK and NF-κB pathways was suppressed by CSSPW treatment, as well as p65 nuclear translocation and ROS production. In contrast, the protein expression of the Nrf2/HO-1 pathway was markedly upregulated.

Conclusions

CSSPW exerts its anti-inflammatory effect via downregulating the production of pro-inflammatory mediators, inhibiting the activation of NF-κB and MAPK pathways, as well as activating Nrf2/HO-1 pathway in LPS-induced RAW264.7 cells.

Recent Updates in Pharmacological Properties of Chitooligosaccharides

Chemical structures derived from marine foods are highly diverse and pharmacologically promising. In particular, chitooligosaccharides (COS) present a safe pharmacokinetic profile and a great source of new bioactive polymers. This review describes the antioxidant, anti-inflammatory, and antidiabetic properties of COS from recent publications. Thus, COS constitute an effective agent against oxidative stress, cellular damage, and inflammatory pathogenesis. The mechanisms of action and targeted therapeutic pathways of COS are summarized and discussed. COS may act as antioxidants via their radical scavenging activity and by decreasing oxidative stress markers. The mechanism of COS antidiabetic effect is characterized by an acceleration of pancreatic islets proliferation, an increase in insulin secretion and sensitivity, a reduction of postprandial glucose, and an improvement of glucose uptake. COS upregulate the GLUT2 and inhibit digestive enzyme and glucose transporters. Furthermore, they resulted in reduction of gluconeogenesis and promotion of glucose conversion. On the other hand, the COS decrease inflammatory mediators, suppress the activation of NF-κB, increase the phosphorylation of kinase, and stimulate the proliferation of lymphocytes. Overall, this review brings evidence from experimental data about protective effect of COS.

Enzymatic Modifications of Chitin, Chitosan, and Chitooligosaccharides

Chitin and its N-deacetylated derivative chitosan are two biological polymers that have found numerous applications in recent years, but their further deployment suffers from limitations in obtaining a defined structure of the polymers using traditional conversion methods. The disadvantages of the currently used industrial methods of chitosan manufacturing and the increasing demand for a broad range of novel chitosan oligosaccharides (COS) with a fully defined architecture increase interest in chitin and chitosan-modifying enzymes. Enzymes such as chitinases, chitosanases, chitin deacetylases, and recently discovered lytic polysaccharide monooxygenases had attracted considerable interest in recent years. These proteins are already useful tools toward the biotechnological transformation of chitin into chitosan and chitooligosaccharides, especially when a controlled non-degradative and well-defined process is required. This review describes traditional and novel enzymatic methods of modification of chitin and its derivatives. Recent advances in chitin processing, discovery of increasing number of new, well-characterized enzymes and development of genetic engineering methods result in rapid expansion of the field. Enzymatic modification of chitin and chitosan may soon become competitive to conventional conversion methods.

O-GlcNAcylation in immunity and inflammation: An intricate system (Review)

Chronic, low‑grade inflammation associated with obesity and diabetes result from the infiltration of adipose and vascular tissue by immune cells and contributes to cardiovascular complications. Despite an incomplete understanding of the mechanistic underpinnings of immune cell differentiation and inflammation, O‑GlcNAcylation, the addition of O‑linked N‑acetylglucosamine (O‑GlcNAc) to cytoplasmic, nuclear and mitochondrial proteins by the two cycling enzymes, the O‑linked N‑acetylglucosamine transferase (OGT) and the O‑GlcNAcase (OGA), may contribute to fine‑tune immunity and inflammation in both physiological and pathological conditions. Early studies have indicated that O‑GlcNAcylation of proteins play a pro‑inflammatory role in diabetes and insulin resistance, whereas subsequent studies have demonstrated that this post‑translational modification could also be protective against acute injuries. These studies suggest that diverse types of insults result in dynamic changes to O‑GlcNAcylation patterns, which fluctuate with cellular metabolism to promote or inhibit inflammation. In this review, the current understanding of O‑GlcNAcylation and its adaptive modulation in immune and inflammatory responses is summarized.

Chitosan oligosaccharide-mediated attenuation of LPS-induced inflammation in IPEC-J2 cells is related to the TLR4/NF-κB signaling pathway

The protective mechanism of chitosan oligosaccharide (COS) against lipopolysaccharides (LPS) -induced inflammatory responses in IPEC-J2 and in mice with DSS dextran sulfate sodium (DSS) -induced colitis is reported. Upon exposure to LPS, the proliferation rate of IPEC-J2 cells markedly decreased, and epithelial cell integrity was compromised. However, COS pretreatment significantly reduced these changes. Low-concentration (200 μg/mL) COS up-regulated Toll-like receptor 4 (TLR4) and nuclear p65 expression, but inhibited LPS-induced expression of nuclear p65, IL-6, and IL-8. Addition of the TLR4 inhibitor reduced nuclear p65, IL-6, and IL-8 expression in IPEC-J2 cells exposed to COS or LPS alone, and a slight up-regulation in nuclear p65 was observed in COS and LPS co-treated cells. Medium-dose COS (600 mg/kg/d) protected against DSS-induced colitis, in which TLR4 and nuclear p65 expression levels were decreased. We postulate that the prevention of both LPS- and DSS -induced inflammatory responses in IPEC-J2 cells and mice by COS are related to the inhibition of the TLR4/NF-κB signaling pathway.

Tailored Enzymatic Synthesis of Chitooligosaccharides with Different Deacetylation Degrees and Their Anti-Inflammatory Activity

By controlled hydrolysis of chitosan or chitin with different enzymes, three types of chitooligosaccharides (COS) with MW between 0.2 and 1.2 kDa were obtained: fully deacetylated (fdCOS), partially acetylated (paCOS), and fully acetylated (faCOS). The chemical composition of the samples was analyzed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry. The synthesized fdCOS was basically formed by GlcN, (GlcN)2, (GlcN)3, and (GlcN)4. On the contrary, faCOS contained mostly GlcNAc, (GlcNAc)2 and (GlcNAc)3, while paCOS corresponded to a mixture of at least 11 oligosaccharides with different proportions of GlcNAc and GlcN. The anti-inflammatory activity of the three COS mixtures was studied by measuring their ability to reduce the level of TNF-α (tumor necrosis factor) in murine macrophages (RAW 264.7) after stimulation with a mixture of lipopolysaccharides (LPS). Only fdCOS and faCOS were able to significantly reduce the production of tumor necrosis factor (TNF)-α at 6 h after stimulation with lipopolysaccharides.

Chitosan oligosaccharides prevent doxorubicin-induced oxidative stress and cardiac apoptosis through activating p38 and JNK MAPK mediated Nrf2/ARE pathway

Doxorubicin (DOX) is one of the most effective chemotherapeutic drugs; however, the incidence of cardiotoxicity compromises its therapeutic index. Oxidative stress and apoptosis are believed to be involved in DOX-induced cardiotoxicity. Chitosan oligosaccharides (COS), the enzymatic hydrolysates of chitosan, have been reported to possess diverse biological activities including antioxidant and anti-apoptotic properties. The objective of the present study was to investigate the potential role of COS against DOX-induced cardiotoxicity, and the effects of COS on apoptosis and oxidative stress in rats and H9C2 cells. Furthermore, we also shed light on the involved pathways during the whole process. For this purpose, first, we demonstrated that COS exhibited a significant protective effect on cardiac tissue by not only inducing a decrease in body and heart growth but also ameliorated oxidative damage and ECG alterations in DOX-treated rats. Second, we found that COS reversed the decrease of cell viability induced by DOX, reduced the intracellular reactive oxygen species (ROS), increased the mitochondrial membrane potential (MMP) and Bcl-2/Bax ratio. COS treatment also results in reduced caspase-3 and caspase-9 expressions, and an increase in the phosphorylation of MAPKs (mitogen-activated protein kinases) in DOX-exposed H9C2 cells. Additionally, cellular homeostasis was re-established via stabilization of MAPK mediated nuclear factor erythroid 2-related factor 2/antioxidant-response element (Nrf2/ARE) signaling and transcription of downstream cytoprotective genes. In summary, these findings suggest that COS could be a potential candidate for the prevention and treatment of DOX-induced cardiotoxicity.

Chitooligosaccharide supplementation in low-fish meal diets for Pacific white shrimp (Litopenaeus vannamei): Effects on growth, innate immunity, gut histology, and immune-related genes expression

This study evaluated the effects of supplementing chitooligosaccharide (COS) in low fish meal (FM) diets on growth, immune response, intestine and hepatopancrease histology, and expression of inflammatory and immune-related genes in Pacific white shrimp (Litopenaeus vannamei). A basal diet was formulated using FM and soybean meal (SM) as primary protein sources and considered as a high FM (HFM) diet, then a low FM (LFM) diet was prepared by substituting 50% of FM with SM and supplemented with 0, 0.3, 0.6, 0.9, 1.2 or 1.5 g COS kg-1 diet (LFM, COS3, COS6, COS9, COS12 and COS15 diets). Each diet was fed to quadruplicate groups of shrimp (0.9 g) to apparent satiation three times daily for eight weeks. At the end of the experiment no significant changes in growth and survival rate were observed among treatments (P > 0.05). FM replacement led to significant (P < 0.05) reduction of serum lysozyme activity and significant improvements were obtained by adding 0.3 or 0.6 g kg-1 COS to the LFM diet. A significant decrease in nitric oxide synthase activity was found in LFM group and no beneficial effects could be achieved by COS application. LFM group showed higher hepatopancrease superoxide dismutase and glutathione peroxidase activities than HFM group and further enhancements were obtained by COS application. Hepatopancrease total antioxidant capacity and alkaline phosphatase activity decreased in LFM group and COS supplementation improved their values. Expression of lysozyme, crustin, Pen3 and proPo genes were significantly up-regulated in hepatopancrease of groups received 0.3-0.9 g COS kg-1 diet. FM substitution enhanced the expression of HSP70 and inflammatory genes such as AIF and TNF in hepatopancrease and intestine, and COS administration at a moderate level down-regulated their expression level. Remarkable enhancement in intestinal fold height was obtained by inclusion of 0.3 or 0.6 g COS kg-1 diet compared to the group received LFM diet. Shrimps fed HFM and COS containing diets exhibited higher number of E-cells within their hepatopancrease tubules than the LFM group. The findings in this study clearly demonstrated that COS could enhance non-specific immune response and antioxidant activity, and ameliorate the negative impacts of high SM diets on gut and hepatopancrease health in pacific white shrimp. The optimum inclusion level of COS seems to be 0.3-0.6 g kg-1 of diet.

Competitive Biological Activities of Chitosan and Its Derivatives: Antimicrobial, Antioxidant, Anticancer, and Anti-Inflammatory Activities

Chitosan is obtained from alkaline deacetylation of chitin, and acetamide groups are transformed into primary amino groups during the deacetylation. The diverse biological activities of chitosan and its derivatives are extensively studied that allows to widening the application fields in various sectors especially in biomedical science. The biological properties of chitosan are strongly depending on the solubility in water and other solvents. Deacetylation degree (DDA) and molecular weight (MW) are the most decisive parameters on the bioactivities since the primary amino groups are the key functional groups of chitosan where permits to interact with other molecules. Higher DDA and lower MW of chitosan and chitosan derivatives demonstrated higher antimicrobial, antioxidant, and anticancer capacities. Therefore, the chitosan oligosaccharides (COS) with a low polymerization degree are receiving a great attention in medical and pharmaceutical applications as they have higher water solubility and lower viscosity than chitosan. In this review articles, the antimicrobial, antioxidant, anticancer, anti-inflammatory activities of chitosan and its derivatives are highlighted. The influences of physicochemical parameters of chitosan like DDA and MW on bioactivities are also described.

Chitosan oligosaccharides enhance lipid droplets via down-regulation of PCSK9 gene expression in HepG2 cells

Chitosan oligosaccharides (COS), linear polymers of N-acetyl-D-glucosamine and deacetylated glucosamine, exhibit diverse pharmacological effects such as antimicrobial, antitumor, antioxidant and anti-inflammatory activities. Here, we explored their hypocholesterolemic effects in vivo and the molecular mechanisms of COS in hepatic cells. Our in vivo study of dyslipidemic ApoE^-/- male mice showed that COS treatment of 500 mg kg^-1 d^-1 for 4 weeks clearly reduced the lipid deposits in the aorta and significantly decreased the hepatic proprotein convertase subtilisin/kexin type 9 (PCSK9) protein levels versus HFD groups (p < 0.05). To elucidate the mechanisms behind these effects, the HepG2 cell line was treated with COS. We found that COS (200 μg/ml) increased the amount of cell-surface low-density lipoprotein receptor (LDLR) and enhanced the lipid droplets in HepG2 cells (p < 0.05). The mRNA levels of LDLR and HMG-CoA protein levels were not altered, and the mRNA levels of PCSK9 were down-regulated by COS treatment for 24 h. We also observed that the expression levels of SREBP-2 (125 kD) and HNF-1α were increased in total cell lysates, but nuclear SREBP-2 (nSREBP-2, 68 kD, the active subunit of SREBP-2) levels were decreased and FOXO3a levels increased in nuclear lysates after COS treatment for 24 h. We demonstrated that one of the reasons for regulation of lipid transfer with COS is that FOXO3a levels are up-regulated by COS, leading to a reduction in the PCSK9 promoter binding capacity of HNF-1α and thus suppressing PCSK9 gene expression, up-regulating LDLR levels, and enhancing the lipid droplets in HepG2 cells. In addition, decreased expression of the PCSK9 gene was also contributed to by down-regulation of SREBP-2 by COS. We further confirmed the effect of suppression of PCSK9 expression by COS by utilizing RNA interference to silence HNF-1α and SREBP-2. Finally, to the best of our knowledge, we are the first to demonstrate that PCSK9 expression and LDLR activity are synergistically changed by a combination of HNF-1α and SREBP-2 after COS treatment. Our findings indicate that COS may regulate PCSK9 to modulate hepatic LDLR abundance and activity.

Effect of dietary chitosan oligosaccharide supplementation on the pig ovary transcriptome

Fecundity improvement is one of the most important economic traits for the swine industry. In this study, we identified 486 differentially expressed genes associated with sow prolificacy from COS administrated sow ovaries by RNA-seq.

Antrodia cinnamomea Oligosaccharides Suppress Lipopolysaccharide-Induced Inflammation through Promoting O-GlcNAcylation and Repressing p38/Akt Phosphorylation

Antrodia cinnamomea (AC), an edible fungus growing in Taiwan, has various health benefits. This study was designed to examine the potential inhibitory effects of AC oligosaccharides on lipopolysaccharide (LPS)-induced inflammatory responses in vitro and in vivo. By trifluoroacetic acid degradation, two oligosaccharide products were prepared from AC polysaccharides at 90 °C (ACHO) or 25 °C (ACCO), which showed different oligosaccharide identities. Compared to ACCO, ACHO displayed better inhibitory effects on LPS-induced mRNA expression of pro-inflammatory cytokines including IL-6, IL-8, IL-1β, TNF-α and MCP-1 in macrophage cells. Further, ACHO significantly suppressed the inflammation in lung tissues of LPS-injected C57BL/6 mice. The potential anti-inflammatory molecular mechanism may be associated with the promotion of protein O-GlcNAcylation, which further skewed toward the marked suppression of p38 and Akt phosphorylation. Our results suggest that the suppressive effect of AC oligosaccharides on inflammation may be an effective approach for the prevention of inflammation-related diseases.