Chitosan oligosaccharide ameliorated obesity by reducing endoplasmic reticulum stress in diet-induced obese rats

Mechanism of action of the bile acid receptor TGR5 in obesity

G protein-coupled receptors (GPCRs) are a large family of membrane protein receptors, and Takeda G protein-coupled receptor 5 (TGR5) is a member of this family. As a membrane receptor, TGR5 is widely distributed in different parts of the human body and plays a vital role in regulating metabolism, including the processes of energy consumption, weight loss and blood glucose homeostasis. Recent studies have shown that TGR5 plays an important role in glucose and lipid metabolism disorders such as fatty liver, obesity and diabetes. With the global obesity situation becoming more and more serious, a comprehensive explanation of the mechanism of TGR5 and filling the gaps in knowledge concerning clinical ligand drugs are urgently needed. In this review, we mainly explain the anti-obesity mechanism of TGR5 to promote the further study of this target, and show the electron microscope structure of TGR5 and review recent studies on TGR5 ligands to illustrate the specific binding between TGR5 receptor binding sites and ligands, which can effectively provide new ideas for ligand research and promote drug research.

Anti-Obesity Effects of Chitosan and Its Derivatives

The number of obese people in the world is rising, leading to an increase in the prevalence of type 2 diabetes and other metabolic disorders. The search for medications including natural compounds for the prevention of obesity is an urgent task. Chitosan polysaccharide obtained through the deacetylation of chitin, and its derivatives, including short-chain oligosaccharides (COS), have hypolipidemic, anti-inflammatory, anti-diabetic, and antioxidant properties. Chemical modifications of chitosan can produce derivatives with increased solubility under neutral conditions, making them potential therapeutic substances for use in the treatment of metabolic disorders. Multiple studies both in animals and clinical trials have demonstrated that chitosan improves the gut microbiota, restores intestinal barrier dysfunction, and regulates thermogenesis and lipid metabolism. However, the effect of chitosan is rather mild, especially if used for a short periods, and is mostly independent of chitosan's physical characteristics. We hypothesized that the major mechanism of chitosan's anti-obesity effect is its flocculant properties, enabling it to collect the chyme in the gastrointestinal tract and facilitating the removal of extra food. This review summarizes the results of the use of COS, chitosan, and its derivatives in obesity control in terms of pathways of action and structural activity.

Anti-Obesity Effect and Mechanism of Chitooligosaccharides Were Revealed Based on Lipidomics in Diet-Induced Obese Mice

Chitooligosaccharide (COS) is a natural product from the ocean, and while many studies have reported its important role in metabolic diseases, no study has systematically elaborated the anti-obesity effect and mechanism of COS. Herein, COSM (MW ≤ 3000 Da) was administered to diet-induced obese mice by oral gavage once daily for eight weeks. The results show that COSM administration reduced body weight; slowed weight gain; reduced serum Glu, insulin, NEFA, TC, TG, and LDL-C levels; increased serum HSL and HDL-C levels; improved inflammation; and reduced lipid droplet size in adipose tissue. Further lipidomic analysis of adipose tissue revealed that 31 lipid species are considered to be underlying lipid biomarkers in COS therapy. These lipids are mainly enriched in pathways involving insulin resistance, thermogenesis, cholesterol metabolism, glyceride metabolism and cyclic adenosine monophosphate (cAMP), which sheds light on the weight loss mechanism of COS. The Western blot assay demonstrated that COSM intervention can improve insulin resistance, inhibit de novo synthesis, and promote thermogenesis and β-oxidation in mitochondria by the AMPK pathway, thereby alleviating high-fat diet-induced obesity. In short, our study can provide a more comprehensive direction for the application of COS in obesity based on molecular markers.

Marine Chitosan-Oligosaccharide Ameliorated Plasma Cholesterol in Hypercholesterolemic Hamsters by Modifying the Gut Microflora, Bile Acids, and Short-Chain Fatty Acids

This study evaluated the cholesterol-alleviating effect and underlying mechanisms of chitosan-oligosaccharide (COS) in hypercholesterolemic hamsters. Male hamsters (n = 24) were divided into three groups in a random fashion, and each group was fed one particular diet, namely a non-cholesterol diet (NCD), a high-cholesterol diet (HCD), and an HCD diet substituting 5% of the COS diet for six weeks. Subsequently, alterations in fecal bile acids (BAs), short-chain fatty acids (SCFAs), and gut microflora (GM) were investigated. COS intervention significantly reduced and increased the plasma total cholesterol (TC) and high-density lipoprotein-cholesterol (HDL-C) levels in hypercholesteremic hamsters. Furthermore, Non-HDL-C and total triacylglycerols (TG) levels were also reduced by COS supplementation. Additionally, COS could reduce and increase food intake and fecal SCFAs (acetate), respectively. Moreover, COS had beneficial effects on levels of BAs and GM related to cholesterol metabolism. This study provides novel evidence for the cholesterol-lowering activity of COS.

GRP78 Activity Moderation as a Therapeutic Treatment against Obesity

Glucose-regulated protein 78 (GRP78), a molecular chaperone, is overexpressed in patients suffering from obesity, fatty liver, hyperlipidemia and diabetes. GRP78, therefore, can be not only a biomarker to predict the progression and prognosis of obesity and metabolic diseases but also a potential therapeutic target for anti-obesity treatment. In this paper, GRP78 inhibitors targeting its ATPase domain have been reviewed. Small molecules and proteins that directly bind GRP78 have been described. Putative mechanisms of GRP78 in regulating lipid metabolism were also summarized so as to investigate the role of GRP78 in obesity and other related diseases and provide a theoretical basis for the development and design of anti-obesity drugs targeting GRP78.

In Vivo and In Silico Investigation of the Anti-Obesity Effects of Lactiplantibacillus plantarum Combined with Chia Seeds, Green Tea, and Chitosan in Alleviating Hyperlipidemia and Inflammation

The increasing prevalence of obesity has become a demanding issue in both high-income and low-income countries. Treating obesity is challenging as the treatment options have many limitations. Recently, diet modification has been commonly applied to control or prevent obesity and its risks. In this study, we investigated novel therapeutic approaches using a combination of a potential probiotic source with prebiotics. Forty-eight adult male Sprague–Dawley rats were selected and divided into seven groups (eight rats per group). The first group was fed a high-fat diet, while the second group was a negative control. The other five groups were orally administered with a probiotic, Lactiplantibacillus plantarum (L. plantarum), and potential prebiotics sources (chia seeds, green tea, and chitosan) either individually or in combination for 45 days. We collected blood samples to analyze the biochemical parameters and dissected organs, including the liver, kidney, and pancreas, to evaluate obesity-related injuries. We observed a more significant decrease in the total body weight by combining these approaches than with individual agents. Moreover, treating the obese rats with this combination decreased serum catalase, superoxide dismutase, and liver malondialdehyde levels. A histopathological examination revealed a reduction in obesity-related injuries in the liver, kidney, and pancreas. Further docking studies indicated the potential role of chia seeds and green tea components in modulating obesity and its related problems. Therefore, we suggest that the daily administration of a pre- and probiotic combination may reduce obesity and its related problems.

Effects of Chitosan Oligosaccharide on Production Performance, Egg Quality and Ovarian Function in Laying Hens with Fatty Liver Syndrome

Simple Summary

Fatty liver syndrome (FLS) often occurs in caged laying hens and can cause decreases in production performance. Chitosan oligosaccharide (COS), degraded from chitin or chitosan, has been demonstrated to prevent metabolic diseases in rodents. In this work, we found that dietary COS supplementation could improve production performance and egg quality in laying hens with FLS. Further study indicated that improved ovarian morphology and function may be involved in these beneficial effects of COS. Specifically, dietary COS supplementation decreased oxidative stress, inflammation and apoptosis in the ovaries of laying hens with FLS. This study provides evidence for the application of COS to improve production performance and egg quality in laying hens with FLS.

Abstract

This study aimed to investigate the role of chitosan oligosaccharide (COS) as an additive in the feed of laying hens with fatty liver syndrome (FLS). Effects on production performance, egg quality as well as ovarian function were determined. A total of 360 Lohmann Pink-shell laying hens (28 weeks old) were randomly assigned to 5 groups (6 replicates × 12 birds). Hens were fed with a basal diet and a high-energy low-protein (HELP) diet supplemented with 0, 200, 400 and 800 mg/kg COS. COS reversed the lowered laying rates, increased feed-to-egg ratios and decreased albumen heights and Haugh units induced by the HELP diet. Additionally, COS improved the ovarian morphologies damaged by the HELP diet. Furthermore, COS enhanced antioxidant enzyme activities, reduced malonaldehyde levels and downregulated the mRNA expressions of nuclear factor kappa B, pro-inflammation cytokine genes and pro-apoptosis-related genes, while it upregulated the mRNA expression of anti-apoptosis-related genes in the ovaries of HELP-diet-fed hens. These findings suggested that dietary COS supplementation could improve production performance and egg quality in laying hens with FLS, and these beneficial effects were linked to improved ovarian morphology, which was attributed to decreased oxidative stress, inflammation and apoptosis in the ovaries.

Effect of chitooligosaccharides with a specific degree of polymerization on multiple targets in T2DM mice

Chitooligosaccharides (COS) are found naturally in the ocean and present a variety of physiological activities, of which hypoglycemic action has attracted considerable research attention. This study aimed to assess the therapeutic effect of COS on mice suffering from type 2 diabetes mellitus (T2DM). COS effectively reduced blood glucose and blood lipid levels and improved glucose tolerance. Furthermore, COS revealed strong inhibitory activity against α-glucosidase, reducing postprandial blood glucose levels. Molecular docking data showed that COS might interact with surrounding amino acids to form a complex and decrease α-glucosidase activity. Additionally, COS enhanced insulin signal transduction and glycogen synthesis while restricting gluconeogenesis in the liver and muscles, reducing insulin resistance (IR) as a result. Moreover, COS effectively protected and restored islet cell function to increase insulin secretion. These results indicated that COS exhibited a significant hypoglycemic effect with multi-target participation. Therefore, COS may serve as a new preventive or therapeutic drug for diabetes to alleviate metabolic syndrome.

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.

Chitosan Oligosaccharide Inhibits the Synthesis of Milk Fat in Bovine Mammary Epithelial Cells through AMPK-Mediated Downstream Signaling Pathway

Simple Summary

In order to study the effect of chitosan oligosaccharides on milk fat synthesis of bovine mammary epithelial cells (BMECs), we did a series of related experiments. The results showed that chitosan oligosaccharide (COS) could inhibit the fatty acid synthesis and promote milk fat decomposition and oxidation through AMPK/SREBP1/SCD1, AMPK/HSL and AMPK/PPARα signaling pathways to reduce the milk fat content in bovine mammary epithelial cells. We elucidated the important role of COS in BMECs lipid metabolism. COS may be the potential small-molecule component in milk cow molecular breeding to regulate milk fat synthesis and metabolism. These findings will help us to further understand the mechanism of COS on milk fat metabolism.

Abstract

Chitosan oligosaccharide (COS) is a variety of oligosaccharides, and it is also the only abundant basic amino oligosaccharide in natural polysaccharides. Chitosan oligosaccharide is a low molecular weight product of chitosan after enzymatic degradation. It has many biological effects, such as lipid-lowering, antioxidant and immune regulation. Previous studies have shown that chitosan oligosaccharide has a certain effect on fat synthesis, but the effect of chitosan oligosaccharide on milk fat synthesis of bovine mammary epithelial cells (BMECs) has not been studied. Therefore, this study aimed to investigate chitosan oligosaccharide’s effect on milk fat synthesis in bovine mammary epithelial cells and explore the underlying mechanism. We treated bovine mammary epithelial cells with different concentrations of chitosan oligosaccharide (0, 100, 150, 200, 400 and 800 μg/mL) for 24 h, 36 h and 48 h respectively. To assess the effect of chitosan oligosaccharide on bovine mammary epithelial cells and determine the concentration and time for chitosan oligosaccharide treatment on cells, several in vitro cellular experiments, including on cell viability, cycle and proliferation were carried out. The results highlighted that chitosan oligosaccharide (100, 150 μg/mL) significantly promoted cell viability, cycle and proliferation, increased intracellular cholesterol content, and reduced intracellular triglyceride and non-esterified fatty acids content. Under the stimulation of chitosan oligosaccharide, the expression of genes downstream of Phosphorylated AMP-activated protein kinase (P-AMPK) and AMP-activated protein kinase (AMPK) signaling pathway changed, increasing the expression of peroxisome proliferator-activated receptor alpha (PPARα) and hormone-sensitive lipase (HSL), but the expression of sterol regulatory element-binding protein 1c (SREBP1) and its downstream target gene stearoyl-CoA desaturase (SCD1) decreased. In conclusion, these results suggest that chitosan oligosaccharide may inhibit milk fat synthesis in bovine mammary epithelial cells by activating the AMP-activated protein kinase signaling pathway, promoting the oxidative decomposition of fatty acids and inhibiting fatty acid synthesis.

Marine Chitooligosaccharide Alters Intestinal Flora Structure and Regulates Hepatic Inflammatory Response to Influence Nonalcoholic Fatty Liver Disease

In this study, C57BL/6 mice were given an HFHSD diet for 8 weeks to induce hepatic steatosis and then given COSM solution orally for 12 weeks. The study found that the HFHSD diet resulted in steatosis and insulin resistance in mice. The formation of NAFLD induced by HFHSD diet was related to the imbalance of intestinal flora. However, after COSM intervention, the abundance of beneficial bacteria increased significantly, while the abundance of harmful bacteria decreased significantly. The HFHSD diet also induced changes in intestinal bacterial metabolites, and the content of short-chain fatty acids in cecal contents after COSM intervention was significantly higher than that in the model group. In addition, COSM not only improved LPS levels and barrier dysfunction in the ileum and colon but upregulated protein levels of ZO-1, occludin, and claudin in the colon and downregulated the liver LPS/TLR4/NF-κB inflammatory pathway. We concluded that the treatment of marine chitooligosaccharide COSM could improve the intestinal microflora structure of the fatty liver and activate an inflammatory signaling pathway, thus alleviating the intrahepatic lipid accumulation induced by HFHSD.

Anti-obesity effects of galacto-oligosaccharides in obese rats

Galacto-oligosaccharides (GOS) are commonly used as prebiotic with a variety of known metabolic benefits; however, whether GOS plays a protective role in obesity remains unknown. Here, we demonstrate that GOS prevented obesity in a rat model of obesity induced by a high-fat diet. Our results showed that GOS effectively slowed weight gain in diet-induced obese rats without affecting energy intake. GOS significantly suppressed the hypertrophy and hyperplasia of white adipose tissue and markedly reduced the ratio of the fat/body. Consistently, GOS significantly improved serum total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels, indicating the weight loss activity of GOS. Interestingly, GOS also significantly increased the expression levels of browning proteins, including uncoupling protein 1, peroxisome proliferator-activated receptor-γ, peroxisome proliferator-activated receptor-γ coactivator 1α, and PR domain 16, in both white and brown adipose tissue. Furthermore, we found that GOS markedly increased the expression levels of liver X receptor α, peroxisome proliferation-activated receptor-α, low-density lipoprotein receptor, and cholesterol 7α-hydroxylase proteins in the liver of obese rats. Taken together, we concluded that GOS inhibits obesity by accelerating the browning of white fat cells and the thermogenesis of brown fat cells and that GOS improves host lipid homeostasis by promoting cholesterol catabolism.

Pharmacokinetics, bioavailability and tissue distribution of chitobiose and chitotriose in rats

Chitooligosaccharides (COSs) have various physiological activities and broad application prospects; however, their pharmacokinetics and tissue distribution remain unclear. In this study, a sensitive and selective ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method for determining chitobiose (COS 2) and chitotriose (COS 3) in rat serum and tissues was developed. This method was successfully validated based on FDA guidelines in terms of selectivity, calibration curves (lower limit of quantification was 0.002 µg/mL for COS 2 and 0.02 µg/mL for COS 3), precision (intra-day relative standard deviation of 0.04%-3.55% and inter-day relative standard deviation of 1.94%-11.63%), accuracy (intra-day relative error of - 1.81%-11.06% and inter-day relative error of - 9.41%-8.63%), matrix effects, recovery (97.10%-101.29%), stability, dilution integrity, and carry-over effects. Then, the method was successfully applied to the pharmacokinetics and tissue distribution study of COS 2 and COS 3 after intragastric and intravenous administration. After intragastric administration, COS 2 and COS 3 were rapidly absorbed, reached peak concentrations in the serum after approximately 0.45 h, and showed rapid elimination with clearances greater than 18.82 L/h/kg and half-lives lower than 6 h. The absolute oral bioavailability of COS 2 and COS 3 was 0.32%-0.52%. COS 2 and COS 3 were widely distributed in Wistar rat tissues and could penetrated the blood-brain barrier without tissue accumulation.

Feeding of cuticles from Tenebrio molitor larvae modulates the gut microbiota and attenuates hepatic steatosis in obese Zucker rats

Insect biomass obtained from large-scale mass-rearing of insect larvae has gained considerable attention in recent years as an alternative and sustainable source of food and feed. A byproduct from mass-rearing of insect larvae is the shed cuticles - the most external components of insects which are a relevant source of the polysaccharide chitin. While it has been shown that chitin modulates the gut microbiota and ameliorates lipid metabolic disorders in obese rodent models, feeding studies dealing with isolated insects' cuticles are completely lacking. Thus, the present study tested the hypothesis that dietary insects' cuticles modulate the gut microbiome and improve hepatic lipid metabolism in obese Zucker rats. To test this hypothesis, three groups of obese Zucker rats were fed a nutrient-adequate, semisynthetic basal diet which was supplemented with either 0% (group O), 1.5% (group O1.5) or 3.0% (group O3.0) Tenebrio molitor cuticles at the expense of cellulose. Oil red O-stained liver sections showed a marked lipid accumulation, but lipid accumulation was clearly less in group O3.0 than in groups O and O1.5. In line with this, hepatic lipid concentrations were 30% lower in group O3.0 than in group O (p < 0.05). No differences were observed across the obese groups regarding liver concentrations of methionine, S-adenosylmethionine and homocysteine. Analysis of cecal microbial community at the family level revealed that the relative abundances of Bifidobacteriaceae, Coriobacteriaceae Erysipelotrichaceae, Lactobacillaceae, Prevotellaceae, Sutterellaceae, unknown Deltaproteobacteria and unknown Firmicutes were higher and those of Anaeroplasmataceae, Desulfovibrionaceae, Eubacteriaceae, Ruminococcaceae, Saccharibacteria and unknown Clostridiales were lower in group O3.0 compared to group O (p < 0.05). Cecal digesta concentrations of total short-chain fatty acids, acetate and butyrate were higher in group O3.0 than in group O (p < 0.05). Targeted plasma metabolomics revealed 53 metabolites differing between groups, amongst which two indole metabolites, indole-3-propionic acid and 3-indoxylsulfate, were markedly elevated in group O3.0 compared to groups O1.5 and O. Regarding that increased abundances of bacteria of the Actinobacteria phylum and Lactobacillaceae family in the gut have been reported to be associated with antisteatotic, hepatoprotective and antiinflammatory effects, the pronounced increases of Bifidobacteriaceae and Coriobacteriaceae (both Actinobacteria), and of Lactobacillaceae in group O3.0 might have contributed to the amelioration of fatty liver.

ER stress in obesity pathogenesis and management

Given the unprecedented global pandemic of obesity, a better understanding of the etiology of adiposity will be necessary to ensure effective management of obesity and related complications. Among the various potential factors contributing to obesity, endoplasmic reticulum (ER) stress refers to a state of excessive protein unfolding or misfolding that is commonly found in metabolic diseases including diabetes mellitus, insulin resistance (IR), and non-alcoholic fatty liver disease, although its role in obesogenesis remains controversial. ER stress is thought to drive adiposity by dampening energy expenditure, making ER stress a likely therapeutic target for the management of obesity. We summarize the role of ER stress and the ER stress response in the onset and development of obesity, and discuss the underlying mechanisms involved with a view to identifying novel therapeutic strategies for obesity prevention and management.

Protective effect and mechanism of chitooligosaccharides on acetaminophen-induced liver injury

Currently, drug-induced liver injury caused by acetaminophen (APAP) is the second leading cause of human liver transplantation. The only clinical antidote treatment for APAP-induced liver injury is N-acetyl-L-cysteine (NAC), which has many side effects. Chitooligosaccharides (COS) are processed from naturally occurring chitin through chemical desalting and deproteinization, biological enzymatic hydrolysis and other processes. In this study, we constructed in vitro and in vivo models of APAP-induced liver injury to study COS of two molecular weights (MWs), which are COST (MW ≤ 1000 Da) and COSM (MW ≤ 3000 Da). The results showed that COST and COSM can significantly reduce the levels of serum ALT and AST and liver MDA, TNF-α, IL-1β and IL-6, and increase the levels and activity of GSH, SOD, GSH-Px and CAT. A mechanistic study found that COST and COSM can significantly reduce the expression of liver CYP2E1, Keap1, p-ASK1/ASK1, p-MKK4/MKK4, p-JNK/JNK, Caspase-3 and Bax and increase the expression of Nrf2, HO-1, eNOS, SOD and Bcl-XL. COST and COSM can inhibit toxic APAP metabolism, inhibit oxidative damage and the apoptosis pathway, increase activation of the liver antioxidant pathway, and ultimately ameliorate APAP-induced liver oxidative damage.

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.

Effect of different bile acids on the intestine through enterohepatic circulation based on FXR

Farnesoid X receptor (FXR) is a nuclear receptor for bile acids (BAs) that is widely expressed in the intestine, liver and kidney. FXR has important regulatory impacts on a wide variety of metabolic pathways (such as glucose, lipid, and sterol metabolism) and has been recognized to ameliorate obesity, liver damage, cholestasis and chronic inflammatory diseases. The types of BAs are complex and diverse. BAs link the intestine with the liver through the enterohepatic circulation. BAs derivatives have entered clinical trials for liver disease. In addition to the liver, the intestine is also targeted by BAs. This article reviews the effects of different BAs on the intestinal tract through the enterohepatic circulation from the perspective of FXR, aiming to elucidate the effects of different BAs on the intestinal tract and lay a foundation for new treatment methods.

Chitin and Chitosan Derivatives as Biomaterial Resources for Biological and Biomedical Applications

Chitin is a long-chain polymer of N-acetyl-glucosamine, which is regularly found in the exoskeleton of arthropods including insects, shellfish and the cell wall of fungi. It has been known that chitin can be used for biological and biomedical applications, especially as a biomaterial for tissue repairing, encapsulating drug for drug delivery. However, chitin has been postulated as an inducer of proinflammatory cytokines and certain diseases including asthma. Likewise, chitosan, a long-chain polymer of N-acetyl-glucosamine and d-glucosamine derived from chitin deacetylation, and chitosan oligosaccharide, a short chain polymer, have been known for their potential therapeutic effects, including anti-inflammatory, antioxidant, antidiarrheal, and anti-Alzheimer effects. This review summarizes potential utilization and limitation of chitin, chitosan and chitosan oligosaccharide in a variety of diseases. Furthermore, future direction of research and development of chitin, chitosan, and chitosan oligosaccharide for biomedical applications is discussed.

Targeted treatment of alcoholic liver disease based on inflammatory signalling pathways

Targeted therapy is an emerging treatment strategy for alcoholic liver disease (ALD). Inflammation plays an important role in the occurrence and development of ALD, and is a key choice for its targeted treatment, and anti-inflammatory treatment has been considered beneficial for liver disease. Surprisingly, immune checkpoint inhibitors have become important therapeutic agents for hepatocellular carcinoma (HCC). Moreover, studies have shown that the combination of inflammatory molecule inhibitors and immune checkpoint inhibitors can exert better effects than either alone in mouse models of HCC. This review discusses the mechanism of hepatic ethanol metabolism and the conditions under which inflammation occurs. In addition, we focus on the potential molecular targets in inflammatory signalling pathways and summarize the potential targeted inhibitors and immune checkpoint inhibitors, providing a theoretical basis for the targeted treatment of ALD and the development of new combination therapy strategies for HCC.

Chitosan protects liver against ischemia-reperfusion injury via regulating Bcl-2/Bax, TNF-α and TGF-β expression

The study aimed to investigate the potential attenuation effect of chitosan in liver ischemia/reperfusion injury (I/R), and its relevant protective mechanisms. Chitosan (200 mg/kg) has been administered orally for 30 days, later animals underwent liver 45 min ischemia and reperfusion for 60 min. Following treatment with chitosan, the levels of serum aminotransferases and lactate dehydrogenase were significantly reduced. Similarly, hepatic (GSH, SOD, CAT, GST and GPx) were enhanced, and the level of tissue malondialdehyde (MDA) was decreased. In addition, inflammatory cytokinesis (TNF-α and TGF-β) have recorded a significant decrease in their mRNA expression and protein levels using qPCR and ELISA respectively. Marked reduction of apoptosis has been indicated by the elevation in BCL2, and decreasing in BAX, Caspace-3 and Cytochrome-c expression levels, which furthermore confirmed by DNA fragmentation assay. The enhancement of the previous parameters resulted in a marked improvement in the liver architectures after chitosan administration. In conclusion, chitosan has proved its efficiency as an anti-inflammatory and antioxidant agent through its inhibitory effect of cytokines and reducing ROS respectively. In addition, chitosan could modulate the changes in histological structure and alleviate apoptosis induced by liver I/R, which recommend it as an efficient agent for protection against liver I/R injury.