Functional Comparison for Lipid Metabolism and Intestinal and Fecal Microflora Enzyme Activities between Low Molecular Weight Chitosan and Chitosan Oligosaccharide in High-Fat-Diet-Fed Rats

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.

Integrating omics and network pharmacology reveals the anti-constipation role of chitosan with different molecular weights in constipated mice

This study aimed to reveal the constipation-relieving role of chitosan (COS) with different molecular weights (1 kDa, 3 kDa and 244 kDa). Compared with COS3K (3 kDa) and COS240K (244 kDa), COS1K (1 kDa) more significantly accelerated gastrointestinal transit and defecation frequency. These differential effects were reflected in the regulation of specific gut microbiota (Desulfovibrio, Bacteroides, Parabacteroides and Anaerovorax) and short-chain fatty acids (propionic acid, butyric acid and valeric acid). RNA-sequencing found that the differential expressed genes (DEGs) caused by different molecular weights of COS were mainly enriched in intestinal immune-related pathways, especially cell adhesion molecules. Furthermore, network pharmacology revealed two candidate genes (Clu and Igf2), which can be regarded as the key molecules for the differential anti-constipation effects of COS with different molecular weights. These results were further verified by qPCR. In conclusion, our results provide a novel research strategy to help understand the differences in the anti-constipation effects of chitosan with different molecular weights.

Antidiabetic Properties of Chitosan and Its Derivatives

Diabetes mellitus is a chronic metabolic disorder. In addition to taking medication, adjusting the composition of the diet is also considered one of the effective methods to control the levels of blood glucose. Chitosan and its derivatives are natural and versatile biomaterials with health benefits. Chitosan has the potential to alleviate diabetic hyperglycemia by reducing hepatic gluconeogenesis and increasing skeletal muscle glucose uptake and utility. Scientists also focus on the glucose-lowering effect of chitosan oligosaccharide (COS). COS supplementation has the potential to alleviate abnormal glucose metabolism in diabetic rats by inhibiting gluconeogenesis and lipid peroxidation in the liver. Both high and low molecular weight chitosan feeding reduced insulin resistance by inhibiting lipid accumulation in the liver and adipose tissue and ameliorating chronic inflammation in diabetic rats. COS can reduce insulin resistance but has less ability to reduce hepatic lipids in diabetic rats. A clinical trial showed that a 3-month administration of chitosan increased insulin sensitivity and decreased body weight and triglycerides in obese patients. Chitosan and COS are considered Generally Recognized as Safe; however, they are still considered to be of safety concerns. This review highlights recent advances of chitosan and its derivatives in the glucose-lowering/antidiabetic effects and the safety.

Biomaterial-Based Therapeutic Strategies for Obesity and Its Comorbidities

Obesity is a global public health issue that results in many health complications or comorbidities, including type 2 diabetes mellitus, cardiovascular disease, and fatty liver. Pharmacotherapy alone or combined with either lifestyle alteration or surgery represents the main modality to combat obesity and its complications. However, most anti-obesity drugs are limited by their bioavailability, target specificity, and potential toxic effects. Only a handful of drugs, including orlistat, liraglutide, and semaglutide, are currently approved for clinical obesity treatment. Thus, there is an urgent need for alternative treatment strategies. Based on the new revelation of the pathogenesis of obesity and the efforts toward the multi-disciplinary integration of materials, chemistry, biotechnology, and pharmacy, some emerging obesity treatment strategies are gradually entering the field of preclinical and clinical research. Herein, by analyzing the current situation and challenges of various new obesity treatment strategies such as small-molecule drugs, natural drugs, and biotechnology drugs, the advanced functions and prospects of biomaterials in obesity-targeted delivery, as well as their biological activities and applications in obesity treatment, are systematically summarized. Finally, based on the systematic analysis of biomaterial-based obesity therapeutic strategies, the future prospects and challenges in this field are proposed.

Protective Effect of Chitosan Oligosaccharide against Hydrogen Peroxide-Mediated Oxidative Damage and Cell Apoptosis via Activating Nrf2/ARE Signaling Pathway

Chitosan oligosaccharide (COS), hydrolyzed and deacetylated from chitosan, has been reported to possess varieties of biological activities. Alzheimer's disease (AD) is a multifactorial progressive neurodegenerative disorder characterized by cognitive decline and memory loss, where oxidative stress was reported to be an overwhelming cause of the occurrence of AD. We have previously reported that COS could significantly decrease cell death, ROS generation, and lipid peroxidation, though the potential mechanism was yet to be determined. This study was designed to investigate the neuroprotective effect of COS against hydrogen peroxide (H2O2)-induced oxidative stress and apoptosis in neuronal SH-SY5Y cells. Our results indicated that COS could dose-dependently scavenge H2O2 in the cell-free systems. Accordingly, COS markedly decreased H2O2-induced cell apoptosis and intracellular ROS generation, while increased antioxidant capacity in SH-SY5Y cells. Further, COS significantly reduced the expression of Bax and upregulated Bcl-2. The mRNA and protein expression levels of nuclear Nrf2, heme oxygenase 1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO1) were significantly increased upon COS treatment. Moreover, Nrf2-siRNA evidently reversed the promotive effect of COS on expression levels of HO-1 and NQO1, and ARE-driven transcriptional activity as determined by double-luciferase reporter gene assay. Besides, COS reversed H2O2-mediated increased phosphorylation of ERK1/2 and p38 MAPK. In conclusion, our findings indicate that COS could protect SH-SY5Y cells from oxidative damage and apoptosis via regulating Nrf2/ARE signaling pathway, which may provide new applications for the prevention and treatment of AD.

Chitosan Oligosaccharide Ameliorates Metabolic Syndrome Induced by Overnutrition via Altering Intestinal Microbiota

Chitosan oligosaccharides (COS) play a prebiotic role in many ways, whereas its function on microbiota is not fully understood. In this study, the effects of COS on metabolic syndrome were initially investigated by testing changes in the physiological indicators after adding COS to the diet of mice with high fat (group H) and low fat (group L). The results showed that COS markedly inhibited the accumulation of body weight and liver fat induced by high-fat diet, as well as restored the elevated concentration of blood glucose and fasting insulin to normal levels. Next, changes of the murine intestinal microbiota were examined. The results exhibited that COS reduced with-in-sample diversity, while the between-sample microbial diversity enhanced. Specifically, COS enriched Clostridium paraputrificum and Clostridium ramosum in the mice on a high-fat diet, while the abundance of Clostridium cocleatum was reduced. As a comparison, Parabacteroides goldsteinii and Bacteroides uniformis increased their abundance in response to COS in the low-fat diet group. Noticeably, a large amount of Akkermansia muciniphila was enriched in both high-fat or low-fat diet groups. Among the differential fecal bacteria, Clostridium ramosume was found to be positively interacted with Faecalibacterim prausnitzii and Clostridium paraputrificum; Clostridium paraputrificum had a positive interactions with Lactococcus chungangensis and Bifidobacterium mongoliense, suggesting that COS probably ameliorate metabolic syndrome through the microbiota in view of the lipid-lowering effects of these interacted bacteria. Furthermore, the gene expression data revealed that COS improved the functions related to intestinal barrier and glucose transport, which could be the trigger and consequence of the variations in gut microbiota induced by COS. Additionally, correlation analysis found that intestinal bacteria are related to physiological parameters, which further supports the mediating role of gut microbiota in the beneficial effect of COS. In summary, our research results provide new evidence for the prebiotic effects of COS.

Low molecular weight chitosan oligosaccharides (LMW-COSs) prevent obesity-related metabolic abnormalities in association with the modification of gut microbiota in high-fat diet (HFD)-fed mice

In this study, the two enzymatic low molecular weight chitosan oligosaccharides (LMW-COSs), LMW-COS-H and LMW-COS-L, were prepared with average MWs of 879.6 Da and 360.9 Da, respectively. Compared to LMW-COS-L, the LMW-COS-H was more effective in improving high-fat diet (HFD)-induced metabolic abnormalities, such as obesity, hyperlipidemia, low-grade inflammation and insulin resistance. The subsequent analysis of gut microbiota showed that the supplement of LMW-COSs caused overall structural and genus/species-specific changes in the gut microbiota, which were significantly correlated with the metabolic parameters. Specifically, both of the LMW-COSs significantly decreased the relative abundance of inflammatory bacteria such as Erysipelatoclostridium and Alistipes, whereas that of the beneficial intestinal bacteria (such as Akkermansia and Gammaproteobacteria) increased significantly. This study suggested that there were potential prebiotic functions of LMW-COSs in HFD fed mice, which regulated the dysfunctional gut microbiota, alleviated low-grade inflammation and maintained the intestinal epithelial barrier.

The new coumarin compound Bis 3 ameliorates cognitive disorder and suppresses brain-intestine-liver systematic oxidative stress in high-fat diet mice

High-fat diet (HFD)-induced systemic oxidative damage is critical to the pathological process of obesity and is associated with energy metabolism and cognitive disorders. In our previous research, the coumarin derivative Bis 3 was shown to improve neurological disorders as a potent free radical scavenger. In this study, a 12-week high-fat diet model was established, and mice were randomly divided into 3 groups: standard diet, high-fat diet, and high-fat diet with Bis 3 treatment. Our results demonstrated that Bis 3 attenuated body weight gain and inhibited the development of insulin resistance in high-fat diet-fed mice. Bis 3 protected against high fat-induced intestinal barrier integrity damage and lipid content disorder. HFD-induced hepatocyte lipid metabolism disorder and hepatocyte damage were also alleviated by Bis 3. Moreover, the results of cognitive tests indicated that Bis 3 attenuated high fat-induced cerebral dysfunction, such as cognitive disorders. Importantly, Bis 3 simultaneously ameliorated oxidative stress in the digestive and central nervous systems. These findings suggest that Bis 3 protects against systematic oxidative stress in HFD-induced obese mice, balancing insulin resistance, lipid metabolic disorders, and cognitive disorders through its antioxidative effects, indicating that Bis 3, a novel free radical scavenger, might represent a new therapeutic strategy for high fat-induced chronic systemic redox imbalance.

Molecular Mechanisms of the Anti-obesity Properties of Agardhiella subulata in Mice Fed a High-Fat Diet

The overweight and obese population has skyrocketed, resulting in a high incidence of metabolic disorders. Agardhiella subulata (AS) contains a variety of beneficial components, such as sulfur-containing polysaccharides (dietary fiber) and astaxanthin, which is considered to have anti-obesity potential. In this study, we investigated the effects and possible mechanisms of dietary AS on high-fat diet (HFD)-induced obesity in mice. AS supplementation significantly reduced HFD-induced weight gain (19%) and the visceral adiposity index (4.1%). In addition, the level of total cholesterol, triglyceride, and low-density lipoprotein was significantly decreased; adiponectin was significantly increased in serum and fecal triglyceride excretion was significantly higher in mice fed AS compared with mice on an HFD. Preadipocyte factor 1 and Sry-box transcription factor 9 that were significantly higher than the levels found for the HFD group lead to reduced adipogenesis. Moreover, accompanying the lipolysis and fatty acid β-oxidation that occur in the AS group, the concentration of non-esterified fatty acids was lowered to 0.4 ± 0.1 mEq/L. In addition, peroxisome proliferator-activated receptor γ and phosphorylation acetyl-CoA carboxylase increased 1.5- and 1-fold, thus increasing the expression of adiponectin and the activation of AMPK and ultimately resulting in lower blood glucose levels. The results of this study suggest that AS supplementation increases lipid excretion and improves energy metabolism to prevent obesity in mice fed a HFD.

The potential roles of chitosan oligosaccharide in prevention of kidney injury in obese and diabetic conditions

Obesity is closely associated with insulin resistance (IR). The most likely links between the two are obesity-mediated systemic low-grade chronic inflammation, endoplasmic reticulum stress and mitochondrial dysfunction, which are all known to contribute to the development of type 2 diabetes (T2DM) and eventually diabetic nephropathy (DN). Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin commonly found in exoskeletons of crustaceans such as shrimp and crab as well as the cell walls of fungi. COS has various biological effects including lipid lowering, anti-inflammation, anti-diabetes, and anti-oxidant effects. Therefore, COS is a potential new therapeutic agent for treatment of the obesity-induced DN condition. It is an abundant natural polymer and therefore freely available. This review includes information regarding the relationship between obesity, IR, T2DM, and DN as well as the potential usefulness of COS in controlling lipid and cholesterol metabolism, T2DM and kidney injury models in both in vivo and in vitro studies. However, evidence is limited regarding the effect of COS on the DN model. Further studies, especially in obesity-induced DN, are needed to support the mechanisms proposed in this 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.

Effects of Chitosan Oligosaccharide on Plasma and Hepatic Lipid Metabolism and Liver Histomorphology in Normal Sprague-Dawley Rats

Chitosan oligosaccharide is known to ameliorate hypercholesterolemia and diabetes. However, some studies found that chitosan oligosaccharide might induce mild to moderate hepatic damage in high-fat (HF) diet-induced obese rats or diabetic rats. Chitosan oligosaccharide can be as a dietary supplement, functional food, or drug. Its possible toxic effects to normal subjects need to be clarified. This study is designed to investigate the effects of chitosan oligosaccharide on plasma and hepatic lipid metabolism and liver histomorphology in normal Sprague-Dawley rats. Diets supplemented with 5% chitosan oligosaccharide have been found to induce liver damage in HF diet-fed rats. We therefore selected 5% chitosan oligosaccharide as an experimental object. Rats were divided into: a normal control diet group and a normal control diet +5% chitosan oligosaccharide group. The experimental period was 12 weeks. The results showed that supplementation of 5% chitosan oligosaccharide did not significantly change the body weight, food intake, liver/adipose tissue weights, plasma lipids, hepatic lipids, plasma levels of AST, ALT, and TNF-α/IL-6, hepatic lipid peroxidation and anti-oxidative enzyme activities, fecal lipids, and liver histomorphology in normal rats. These findings suggest that supplementation of 5% chitosan oligosaccharide for 12 weeks may not induce lipid metabolism disorder and liver toxicity in normal rats.

Effects of dietary chitosan on growth rate, small intestinal morphology, nutrients apparent utilization and digestive enzyme activities of growing Huoyan geese

Dietary chitosan (CS) supplementation could improve the growth rate, small intestinal morphology, nutrients apparent digestibility and digestive enzyme activities in pigs, broiler chickens, rats and fish, whereas no data has been reported about the effect of CS on the growing Huoyan geese. Therefore, this study was designed to investigate the effects of CS on growth rate, small intestinal morphology, nutrients apparent utilization and digestive enzyme activities of growing Huoyan geese. Three hundred and twenty (28 days of age, gender balance) Huoyan geese were randomly divided into control, CS100, CS200 and CS400 groups (based on BW) with 20 geese per pen and 4 replicates pen per group, and the feeding experiment lasted for 4 weeks. The 4 diets contained 0, 100, 200 and 400 mg CS per kg feed, respectively. The results showed that CS200 groups had higher average daily gain, final BW, apparent utilization of DM and CP, and lower feed/gain ratio compared with the control group (P < 0.05). Meanwhile, CS100 and CS200 groups had higher villus height, villus height/crypt depth ratio and lower crypt depth in duodenum and jejunum than those in the control group (P < 0.05). The geese in CS100 and CS200 groups had higher villus height, villus height/crypt depth ratio and lower crypt depth of ileum compared with those in control and CS400 groups (P < 0.05). In addition, compared with the control group, CS200 group has higher trypsin activities and lower lipase activities in duodenal, jejunal and ileal contents (P < 0.05). The results suggested that addition of 200 mg/kg CS had positive effects on growth rate, small intestinal morphology, nutrients apparent utilization and digestive enzyme activities of growing Huoyan geese.

Effects of dietary supplementation of chitosan on carcass composition and meat quality in growing Huoyan geese

This present study was conducted to investigate the effects of dietary supplementation of chitosan (CS) on carcass composition and meat quality in growing Huoyan geese. A total of 320 (28-day-old) growing Huoyan geese (sex balance) with similar body weight were randomly divided into the following 4 main groups: basal diet (control), basal diet + 100 mg/kg CS (CS₁₀₀), basal diet + 200 mg/kg CS (CS₂₀₀), and basal diet + 400 mg/kg CS (CS₄₀₀) groups. Each group includes 4 replicates with 20 geese per replicate, and the feeding trail lasted for 4 wk. The results showed that the geese in CS₂₀₀ group had lower abdominal fat percentage, b∗ value, shear force, crude fat content, and drip loss of breast and thigh muscle than those in the control group (P < 0.05). In addition, the CS₂₀₀ group had higher glutamic acid, glycine, lysine, valine, total nonessential amino acids, total essential amino acids, total amino acids, C22:0, C16:1, C18:1, C20:1, C20:2, C20:5, total monounsaturated fatty acids concentration and polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA) ratio and lower total SFA, total PUFA concentration, and total n-6:n-3 ratio in breast muscle than the control group (P < 0.05). Taken together, these results indicated that addition of 200 mg/kg CS improved meat quality in growing Huoyan geese through altering slaughter performance, meat traits, amino acids, and fatty acids composition.

Effects of dietary supplementation of chitosan on immune function in growing Huoyan geese

This present experiment was performed to investigate the effects of dietary supplementation of chitosan (CS) on immune function in growing Huoyan geese. A total of 320 28-day-old healthy growing Huoyan geese (sex balance) with similar body weight were randomly allotted into control, CS100, CS200, and CS400 groups. Each group includes 4 replicates with 20 geese per replicate, and the feeding trial lasted for 4 wk. The 4 diets contained 0, 100, 200, and 400 mg CS per kg feed, respectively. The results showed that compared with the control group, the relative weight of thymus, serum concentrations of IGF-I, INS, GH, T3, T4, IgM, IgG, IgA, complement C3, and IL-2 in CS200 group were significantly higher at both 42 and 56 D of age, respectively (P < 0.05). In addition, relative weight of bursa of fabricius (BF), spleen, serum complement C4, and TNF-a concentrations in CS200 group were higher at 56 D of age (P < 0.05), no differences were observed at 42 D of age (P > 0.05). These results indicated that addition of 200 mg/kg CS enhanced immune organs weight, serum concentrations of immunoglobulins, complements, hormone, as well as cytokines, and improved immune function of growing Huoyan geese.

Residues of acidic chitinase cause chitinolytic activity degrading chitosan in porcine pepsin preparations

Commercially available porcine pepsin preparations have been used for the production of chitooligosaccharides with various biomedical activities. However, the origin of this activity is not well understood. Here we show that the chitosan-degrading activity is conferred by residues with chitinolytic activity of truncated forms of acidic chitinase (Chia) persisting in the pepsin preparation. Chia is an acid-stable and pepsin-resistant enzyme that degrades chitin to produce N-acetyl-D-glucosamine dimer. We found that Chia can be truncated by pepsin under stomach-like conditions while maintaining its enzymatic activity. Similarly to the full-length protein, truncated Chia as well as the pepsin preparations digested chitosan with different degrees of deacetylation (DD: 69-84%) with comparable degradation products. The efficiency was DD-dependent with a marked decrease with higher DD, indicating that the chitosan-degrading activity in the pepsin preparation is due to the chitinolytic activity rather than chitosanolytic activity. We suggest that natural or recombinant porcine Chia are suitable for producing chitooligosaccharides for biomedical purposes.

Chitosan Oligosaccharide Ameliorates Nonalcoholic Fatty Liver Disease (NAFLD) in Diet-Induced Obese Mice

Nonalcoholic fatty liver disease (NAFLD) is a global epidemic, and there is no standard and efficient therapy for it. Chitosan oligosaccharide (COS) is widely known to have various biological effects, and in this study we aimed to evaluate the liver-protective effect in diet-induced obese mice for an enzymatically digested product of COS called COS23 which is mainly composed of dimers and trimers. An integrated analysis of the lipidome and gut microbiome were performed to assess the effects of COS23 on lipids in plasma and the liver as well as on intestinal microbiota. Our results revealed that COS23 obviously attenuated hepatic steatosis and ameliorated liver injury in diet-induced obese mice. The hepatic toxic lipids—especially triglycerides (TGs) and free fatty acids (FFAs)—were decreased dramatically after COS23 treatment. COS23 regulated lipid-related pathways, especially inhibiting the expressions of FFA-synthesis-related genes and inflammation-related genes. Furthermore, COS23 could alter lipid profiles in plasma. More importantly, COS23 also decreased the abundance of Mucispirillum and increased the abundance of Coprococcus in gut microbiota and protected the intestinal barrier by up-regulating the expression of tight-junction-related genes. In conclusion, COS23, an enzymatically digested product of COS, might serve as a promising candidate in the clinical treatment of NAFLD.

A Review of the Preparation, Analysis and Biological Functions of Chitooligosaccharide

Chitooligosaccharide (COS), which is acknowledged for possessing multiple functions, is a kind of low-molecular-weight polymer prepared by degrading chitosan via enzymatic, chemical methods, etc. COS has comprehensive applications in various fields including food, agriculture, pharmacy, clinical therapy, and environmental industries. Besides having excellent properties such as biodegradability, biocompatibility, adsorptive abilities and non-toxicity like chitin and chitosan, COS has better solubility. In addition, COS has strong biological functions including anti-inflammatory, antitumor, immunomodulatory, neuroprotective effects, etc. The present paper has summarized the preparation methods, analytical techniques and biological functions to provide an overall understanding of the application of COS.

Islet-like clusters derived from skeletal muscle-derived stem/progenitor cells for autologous transplantation to control type 1 diabetes in mice

A population of muscle-derived stem/progenitor cells (MDSPCs) contained in skeletal muscle is responsible for muscle regeneration. MDSPCs from mouse muscle have been shown to be capable of differentiating into pancreatic islet-like cells. However, the potency of MDSPCs to differentiate into functional islet-like cluster remains to be confirmed. The therapeutic potential of autologous MDSPCs transplantation on type 1 diabetes still remains unclear. Here, we investigated a four-stage method to induce the differentiation of MDSPCs into insulin-producing clusters in vitro, and tested the autologous transplantation to control type 1 diabetes in mice. MDSPCs isolated from the skeletal muscles of mice possessed the ability to form islet-like clusters through several stages of differentiation. The expressions of pancreatic progenitor-related genes, insulin, and islet-related genes were significantly upregulated in islet-like clusters determined by the quantitative reverse transcription polymerase chain reaction. The autologous islet-like clusters transplantation effectively improved hyperglycaemia and glucose intolerance and increased the survival rate in streptozotocin-induced diabetic mice without the use of immunosuppressants. Taken together, these results provide evidence that MDSPCs from murine muscle tissues are capable of differentiating into insulin-producing clusters, which possess insulin-producing ability in vitro and in vivo, and have the potential for autologous transplantation to control type 1 diabetes.

Effects of low-molecular-weight chitosan on the growth performance, intestinal morphology, barrier function, cytokine expression and antioxidant system of weaned piglets

Background

Chitosan was used as an alternative to promote the growth of weaned piglets. And low-molecular-weight chitosan (LC) is one of chitosan derivatives and maintain beneficial biological properties of chitoson. The present experiment was carried out to examine the effects of LC on the growth performance, intestinal morphology, barrier function, cytokine expression, and antioxidant system of weaned piglets.

Results

A total of 40 piglets weaned at 21 d of age, with average body weight 6.37 ± 0.08 kg, were randomly assigned (5 pens/diet; 4 pigs/pen) to 2 treatments (a basal diet and the basal diet supplemented with 50 mg/kg LC) and were fed for 28 d. Compared with the control group, average daily feed intake (ADFI), and the expression of intestinal barrier protein ZO-1 was increased (P < 0.05) when the piglets fed the diet supplemented with LC. No significant differences were found in average daily gain (ADG, P > 0.05), gain-to-feed ratio (G:F, P > 0.05), the incidence of diarrhea (P > 0.05), or the antioxidant capacity (P > 0.05) between two groups. The expression of IL-1β and TNF-α in jejunal mucosa were significantly decreased (P < 0.05) in piglets fed the LC-supplemented diet in comparison to the control.

Conclusion

The results of this study indicate that dietary supplementation with LC at 50 mg/kg was effective for enhancing the growth performance in weaned piglets, improving intestinal barrier function and alleviating intestinal inflammation.

Anti-Obesity Effect of Chitosan Oligosaccharide Capsules (COSCs) in Obese Rats by Ameliorating Leptin Resistance and Adipogenesis

Obesity is a global disease that causes many metabolic disorders. However, effective agents for the prevention or treatment of obesity remain limited. This study investigated the anti-obesity effect and mechanism of chitosan oligosaccharide capsules (COSCs) on rats suffering from obesity induced by a high-fat diet (HFD). After the eight-week administration of COSCs on obese rats, the body weight gain, fat/body ratio, and related biochemical indices were measured. The hepatic expressions of the leptin signal pathway (JAK2-STAT3) and gene expressions of adipogenesis-related targets were also determined. Our data showed that COSCs can regulate body weight gain, lipids, serum alanine aminotransferase, and aspartate aminotransferase, as well as upregulate the hepatic leptin receptor-b (LepRb) and the phosphorylation of JAK2 and STAT3. Meanwhile, marked increased expressions of liver sterol regulatory element-binding protein-1c, fatty acid synthase, acetyl-CoA carboxylase, 3-hydroxy-3-methylglutaryl-CoA reductase, adiponectin, adipose peroxisome proliferator-activated receptor γ, CCAAT-enhancer binding protein α, adipose differentiation-related protein, and SREBP-1c were observed. The results suggested that COSCs activate the JAK2-STAT3 signaling pathway to alleviate leptin resistance and suppress adipogenesis to reduce lipid accumulation. Thus, they can potentially be used for obesity treatment.

Marine polysaccharides attenuate metabolic syndrome by fermentation products and altering gut microbiota: An overview

Marine polysaccharides (MPs), including plant, animal, and microbial-derived polysaccharides, can alleviate metabolic syndrome (MetS) by different regulation mechanisms. MPs and their derivatives can attenuate MetS by vary cellular signal pathways, such as peroxisome proliferator-activated receptor, 5' adenosine monophosphate-activated protein kinase, and CCAAT/enhancer binding protein-α. Also, most of MPs cannot be degraded by human innate enzymes, but they can be degraded and fermented by human gut microbiota. The final metabolic products of these polysaccharides are usually short-chain fatty acids (SCFAs), which can change the gut microbiota ecology by altering the existing percentage of special microorganisms. In addition, the SCFAs and changed gut microbiota can regulate enteroendocrine hormone secretion, blood glucose, lipid metabolism levels, and other MetS symptoms. Here, we summarize the up-to-date findings on the effects of MPs, particularly marine microbial-derived polysaccharides, and their metabolites on attenuating MetS.

Fish Oil Supplementation Alleviates the Altered Lipid Homeostasis in Blood, Liver, and Adipose Tissues in High-Fat Diet-Fed Rats

This study investigated the effects of dietary supplementation of fish oil on the signals of lipid metabolism involved in hepatic cholesterol and triglyceride influx and excretion in high-fat diet (HFD)-fed rats. Fish oil (FO) repressed body (HFD, 533 ± 18.2 g; HFD+FO, 488 ± 28.0 g, p < 0.05) and liver weights (HFD, 5.7 ± 0.6 g/100 g of body weight; HFD+FO, 4.8 ± 0.4 g/100 g of body weight, p < 0.05) in HFD-fed rats. Fish oil could also improve HFD-induced imbalance of lipid metabolism in blood, liver, and adipose tissues including the significant decreases in plasma and liver total cholesterol (TC) (plasma-HFD, 113 ± 33.6 mg/dL; HFD+FO, 50.0 ± 5.95 mg/dL, p < 0.05; liver-HFD, 102 ± 13.0 mg/g liver; [corrected] HFD+FO, 86.6 ± 7.81 mg/g liver, [corrected] p < 0.05), blood, liver, and adipose triglyceride (TG) (blood-HFD, 52.5 ± 20.4 mg/dL; HFD+FO, 29.8 ± 4.30 mg/dL, p < 0.05; liver-HFD, 56.2 ± 10.0 mg/g liver; [corrected] HFD+FO, 30.3 ± 5.28 mg/g liver, [corrected] p < 0.05; adipose-HFD, 614 ± 73.2 mg/g liver, [corrected] HFD+FO, 409 ± 334 mg/g of adipose tissue, [corrected] p < 0.05), and low density (HFD, 79.8 ± 40.9 mg/dL; HFD+FO, 16.6 ± 5.47 mg/dL, p < 0.05) and very-low-density (HFD, 49.7 ± 33.3 mg/dL; HFD+FO, 10.4 ± 3.45 mg/dL, p < 0.05) lipoprotein and the significant increases in fecal TC (HFD, 12.2 ± 0.67 mg/g feces; [corrected] HFD+FO, 16.3 ± 2.04 mg/g feces, [corrected] < 0.05) and TG (HFD, 2.09 ± 0.10 mg/g feces; [corrected] HFD+FO, 2.38 ± 0.22 mg/g feces, [corrected] p < 0.05) and lipoprotein lipase activity of adipose tissues (HFD, 16.6 ± 3.64 μM p-nitrophenol; HFD+FO, 24.5 ± 4.19 μM p-nitrophenol, p < 0.05). Moreover, fish oil significantly activated the protein expressions of hepatic lipid metabolism regulators (AMPKα and PPARα) and significantly regulated the lipid-transport-related signaling molecules (ApoE, MTTP, ApoB, Angptl4, ApoCIII, ACOX1, and SREBPF1) in blood or liver of HFD-fed rats. These results suggest that fish oil supplementation improves HFD-induced imbalance of lipid homeostasis in blood, liver, and adipose tissues in rats.

Low-Molecular-Weight Chitosan Supplementation Increases the Population of Prevotella in the Cecal Contents of Weanling Pigs

Low-molecular-weight chitosan (LC) promoted growth in weaned piglets as an alternative to feed-grade antibiotics. To investigate the influence of LC supplementation on piglets' gut microbiome and compare the differences in community composition between LC and antibiotics with ZnO addition, we assessed the cecal microbial community by 16S rRNA gene sequencing with three treatments consisting of basal diet (CTR group), basal diet with low-molecular-weight chitosan (LC group), and basal diet with antibiotic and ZnO (AZ group). LC decreased pH more than AZ did in the cecum (both compared to CTR). Beta diversity analysis showed that community structure was distinctly different among the CTR, LC, and AZ treatments, indicating that either LC or AZ treatment modulated the piglet microbiota. Bacteroidetes, Firmicutes, and Proteobacteria dominated the community [>98% of operational taxonomic units (OTUs)] in piglet cecal contents. Compared to CTR, both LC, and AZ increased the relative abundance of Bacteroidetes while they decreased the count of Firmicutes and AZ decreased the population of Proteobacteria. In CTR the top four abundant genera were Prevotella (~10.4%), Succinivibrio (~6.2%), Lactobacillus (~5.6%), and Anaerovibrio (5.4%). Both LC and AZ increased the relative abundance of Prevotella but decreased the ratio of Lactobacillus when they compared with CTR. Moreover, LC increased the relative abundance of Succinivibrio and Anaerovibrio while AZ decreased them. The microbial function prediction showed LC enriched more pathways in the metabolism of cofactors and vitamins than CTR or AZ did. LC may potentially function as an alternative to feed-grade antibiotics in weaned piglets due to its beneficial regulation of the intestinal microbiome.