Uso de quitina e quitosana como adsorventes de amônia de efluentes aquícolas: revisão de literatura / Use of chitin and quitosan as adsorvents of ammonia of aquaculture effluents: a literature review / Uso de quitina y quitosana como adsorbentes de amonia de efluentes acuícolas: revisión de literatura

Os resíduos provenientes da aquicultura são derivados da ração e da excreção dos peixes e podem estar sedimentados, suspensos ou dissolvidos, ocasionando elevados valores de DBO, DQO, nitrogênio e fósforo. A produção de camarões no Brasil tem gerado elevadas quantidades de resíduos sólidos, tendo em vista que os exoesqueletos dos camarões correspondem a cerca de 40% do seu peso total, resultando num forte impacto ambiental. Diversas pesquisas envolvendo a quitina estão sendo desenvolvidas na área de tratamento de água, devido principalmente a sua capacidade de formar filme, sendo utilizada em sistemas filtrantes. Este polissacarídeo também pode ser utilizado como agente floculante no tratamento de efluentes, como adsorvente na clarificação de óleos, e principalmente na produção de quitosana. Atualmente a quitosana possui aplicações multidimensionais, desde áreas como a nutrição humana, biotecnologia, ciência dos materiais, indústria farmacêutica, agricultura, terapia genética e proteção ambiental. A quitosana é muito eficiente na remoção de poluentes em diferentes concentrações. Apresenta alta capacidade e grande velocidade de adsorção, boa eficiência e seletividade tanto em soluções que possuem altas ou baixas concentrações. O uso da biotecnologia, através do processo de adsorção utilizando adsorventes naturais e baratos, como a quitina e quitosana, minimiza os impactos ambientais da aquicultura tanto em relação aos provocados pelo lançamento de efluentes no meio ambiente quanto aos causados pelo descarte inadequado dos resíduos do processamento de camarões.(AU)

Aquaculture residues are derived from fish feed and excretion and may be sedimented, suspended or dissolved, resulting in high BOD, COD, nitrogen and phosphorus values. Shrimp production in Brazil has generated high amounts of solid waste, since shrimp exoskeletons account for about 40% of their total weight, resulting in a strong environmental impact. Several researches involving chitin are being developed in the area of water treatment, mainly due to its ability to form film, being used in filter systems. This polysaccharide can also be used as a flocculating agent in the treatment of effluents, as an adsorbent in the clarification of oils, and especially in the production of chitosan. Currently, chitosan has multidimensional applications, from areas such as human nutrition, biotechnology, materials science, pharmaceutical industry, agriculture, gene therapy and environmental protection. Chitosan is very efficient in the removal of pollutants at different concentrations. It presents high capacity and high adsorption velocity, good efficiency and selectivity both in solutions that have high or low concentrations. The use of biotechnology, through the adsorption process using natural and cheap adsorbents such as chitin and chitosan, minimizes the environmental impacts of aquaculture both in relation to those caused by the release of effluents into the environment and those caused by the inappropriate disposal of processing residues of shrimps.(AU)

Los residuos procedentes de la acuicultura se derivan de la ración y de la excreción de los peces y pueden estar sedimentados, suspendidos o disueltos, ocasionando elevados valores de DBO, DQO, nitrógeno y fósforo. La producción de camarones en Brasil ha generado grandes cantidades de residuos sólidos, teniendo en cuenta que los exoesqueletos de los camarones corresponden a cerca del 40% de su peso total, resultando en un fuerte impacto ambiental. Varias investigaciones involucrando la quitina se están desarrollando en el área de tratamiento de agua, debido principalmente a su capacidad de formar película, siendo utilizada en sistemas filtrantes. Este polisacárido también puede ser utilizado como agente floculante en el tratamiento de efluentes, como adsorbente en la clarificación de aceites, y principalmente en la producción de quitosana. Actualmente la quitosana posee aplicaciones multidimensionales, desde áreas como la nutrición humana, biotecnología, ciencia de los materiales, industria farmacéutica, agricultura, terapia genética y protección ambiental. La quitosana es muy eficiente en la eliminación de contaminantes en diferentes concentraciones. Presenta alta capacidad y gran velocidad de adsorción, buena eficiencia y selectividad tanto en soluciones que poseen altas o bajas concentraciones. El uso de la biotecnología, a través del proceso de adsorción utilizando adsorbentes naturales y baratos, como la quitina y quitosana, minimiza los impactos ambientales de la acuicultura tanto en relación a los provocados por el lanzamiento de efluentes en el medio ambiente en cuanto a los causados por el descarte inadecuado de los residuos del procesamiento de camarones.(AU)

Gallocatechin­silver nanoparticle impregnated cotton gauze patches enhance wound healing in diabetic rats by suppressing oxidative stress and inflammation via modulating the Nrf2/HO-1 and TLR4/NF-κB pathways.

This study is designed to investigate the combination of gallocatechin (GC) and silver nanoparticles (AgNPs) for its wound healing ability in diabetic rats. Thirty male Sprague Dawley rats were randomly divided into 5 groups: 1. Normal control rats dressed with blank CGP1; 2. Diabetic rats dressed with blank CGP1; 3. Diabetic rats dressed with 13.06µM of GC; 4. Diabetic rats dressed with 26.12 µM of GC; 5. Diabetic rats dressed with 0.1% silver sulfadiazine patches. GC-AgNPs-CGP dressed diabetic rats showed significant FBG reduction, prevented the body weight losses and reduced the oxidative stress by lowering MDA content and elevated antioxidant enzymes such as SOD, CAT and GPx in wound healing skin of diabetic rats when compared to normal CGP. Besides, mRNA expression of Nrf2, Nqo-1, and Ho-1 was upregulated with downregulated expression of Keap-1 mRNA, which is supported by immunohistochemistry. Furthermore, GC-AgNPs-CGP dressing increased growth factors such as VEGF, EGF, TGF-ß, and FGF-2 while decreasing MMP-2 in the skin of diabetic wound rats. In vitro permeation study demonstrated rapid GC release and permeation with a flux of 0.061 and 0.143 mg/sq.cm/h. In conclusion, the results indicated that GC-AgNPs-CGP dressing on diabetic wound rats modulated oxidative stress and inflammation with elevated growth factors; increased collagen synthesis thereby significantly improved the wound healing and could be beneficial for the management of diabetic wounds.

Combining chitin biological conduits with small autogenous nerves and platelet-rich plasma for the repair of sciatic nerve defects in rats.

AIMS: Peripheral nerve defects are often difficult to recover from, and there is no optimal repair method. Therefore, it is important to explore new methods of repairing peripheral nerve defects. This study explored the efficacy of nerve grafts constructed from chitin biological conduits combined with small autogenous nerves (SANs) and platelet-rich plasma (PRP) for repairing 10-mm sciatic nerve defects in rats. METHODS: To prepare 10-mm sciatic nerve defects, SANs were first harvested and PRP was extracted. The nerve grafts consisted of chitin biological conduits combined with SAN and PRP, and were used to repair rat sciatic nerve defects. These examinations, including measurements of axon growth efficiency, a gait analysis, electrophysiological tests, counts of regenerated myelinated fibers and observations of their morphology, histological evaluation of the gastrocnemius muscle, retrograde tracing with Fluor-Gold (FG), and motor endplates (MEPs) distribution analysis, were conducted to evaluate the repair status. RESULTS: Two weeks after nerve transplantation, the rate and number of regenerated axons in the PRP-SAN group improved compared with those in the PRP, SAN, and Hollow groups. The PRP-SAN group exhibited better recovery in terms of the sciatic functional index value, composite action potential intensity, myelinated nerve fiber density, myelin sheath thickness, and gastrectomy tissue at 12 weeks after transplantation, compared with the PRP and SAN groups. The results of FG retrograde tracing and MEPs analyses showed that numbers of FG-positive sensory neurons and motor neurons as well as MEPs distribution density were higher in the PRP-SAN group than in the PRP or SAN group. CONCLUSIONS: Nerve grafts comprising chitin biological conduits combined with SANs and PRP significantly improved the repair of 10-mm sciatic nerve defects in rats and may have therapeutic potential for repairing peripheral nerve defects in future applications.

In ovo supplementation of chitooligosaccharide and chlorella polysaccharide affects cecal microbial community, metabolic pathways, and fermentation metabolites in broiler chickens.

The chitooligosaccharide (COS) and chlorella polysaccharide (CPS) have been used as feed supplements in the poultry industry for improving growth performance and immunity. However, the benefits of these prebiotics on the gut health of chickens when used in early nutrition are unknown. This study evaluated the effects of in ovo feeding of COS and CPS on the cecal microbiome, metabolic pathways, and fermentation metabolites of chickens. A total of 240 fertile eggs were divided into 6 groups (n = 4; 10 eggs/replicate): 1) no-injection control, 2) normal saline control, 3) COS 5 mg, 4) COS 20 mg, 5) CPS 5 mg, and 6) CPS 20 mg injection. On day 12.5 of egg incubation, test substrate was injected into the amniotic sac of eggs in respective treatments. The hatched chicks were raised for 21 D under standard husbandry practices. On day 3 and 21, cecal digesta were collected to determine microbiota by shotgun metagenomic sequencing and short-chain fatty acids by gas chromatography. The cecal microbial composition was not different (P > 0.05) among the treatment groups on day 3 but was different (P < 0.05) on day 21. At the species level, the polysaccharide-utilizing bacteria including Lactobacillus johnsonii, Bacteroides coprocola, and Bacteroides salanitronis were higher in the COS group, whereas the relative abundance of some opportunistic pathogenic bacteria were lower than those in the CPS and control groups. At the functional level, the pathways of gluconeogenesis, L-isoleucine degradation, L-histidine biosynthesis, and fatty acid biosynthesis were enriched in the COS group. In addition, propionic acid content was higher (P < 0.05) in the COS group. A network based on the correlation between the COS and other factors was constructed to illuminate the potential action mechanism of the COS in chicken early nutrition. In conclusion, in ovo inoculation of COS 5 mg showed positive effects on the cecal microbiota, metabolic pathways, and propionic acid, thus can be used as in ovo feeding to modulate the gut health of chickens.

Effects of oligochitosan on the growth, immune responses and gut microbes of tilapia (Oreochromis niloticus).

The immunomodulatory effects of oligochitosan have been demonstrated in several fish. However, the underlying mechanisms are not well characterized. The profound interplay between gut microbes and aquaculture has received much scientific attention but understanding the alternations of microbes populating in gut of tilapia (Oreochromis niloticus) fed with oligochitosan remains enigmatic. In this study, the effects of oligochitosan on the growth, immune responses and gut microbes of tilapia were investigated. The feeding trial was conducted in triplicates with the control diet supplemented with oligochitosan at different concentrations (0, 100, 200, 400 or 800 mg/kg). Following a six-week feeding trial, body weights of the fish supplemented with 200 mg/kg and 400 mg/kg oligochitosan were significantly higher than that of the control group. To address the immune responses stimulated by oligochitosan, by the quantitative real time PCR (qRT-PCR), the mRNA expression levels of CSF, IL-1ß, IgM, TLR2 and TLR3 genes from head kidney were all significantly up-regulated in the 400 mg/kg group compared to the control. To characterize the gut microbes, bacterial samples were collected from the foregut, midgut, and hindgut, respectively and were subjected to high-throughput sequencing of 16S rDNA. The results showed that significantly lower abundance of Fusobacterium was detected in the hindgut of 400 mg/kg group compared to the control. Additionally, beta-diversity revealed that both gut habitat and oligochitosan had effects on the gut bacterial assembly. To further elucidate the mechanism underlying the effects of oligochitosan on bacterial assembly, the results showed that difference dosages of dietary oligochitosan could alter the specific metabolic pathways and functions of the discriminatory bacterial taxa, resulting in the different bacterial assemblies. To test the antibacterial ability of tilapia fed with oligochitosan, when the tilapias were challenged with Aeromonas hydrophila, the mortality of groups fed with dietary oligochitosan was significantly lower than that of the control. Taken together, appropriate dietary oligochitosan could improve growth, immune responses and alter the bacterial flora in the intestine of tilapia, so as to play a role in fighting against the bacterial infection.

Effect of chitooligosaccharides on human gut microbiota and antiglycation.

Chitooligosaccharides (COS) have garnered great attention in the field of human healthcare. The prebiotic activities and antiglycation of COS were investigated using a combination of in vitro and in vivo studies. COS supplementation dramatically increased the levels of acetic acid, while reducing the concentrations of propionic and butyric acids. It also decreased the total bacterial population; however, it did not affect diversity and richness of the gut microbiota. In addition, COS modulated the gut microbiota composition by increasing Bacteroidetes, decreasing Proteobacteria and Actinobacteria, and lowering the Firmicutes/Bacteroidetes ratio. COS promoted the generation of beneficial Bacteroides and Faecalibacterium genera, while suppressing the pathogenic Klebsiella genus. The antiglycation activity of COS and acetic acid was dose-dependent. Furthermore, COS prevented the decrease of serum Nε-(carboxymethyl) lysine (CML) level caused by CML ingestion in a mouse model of diet-induced obesity. To improve host health, COS could be potential prebiotics in food products.

Enzymatic preparation of chitooligosaccharides and their anti-obesity application.

Chitooligosaccharides (COS) are derived from chitosan, which can be used as nutraceuticals and functional foods. Because of their various biological activities, COS are widely used in the food, medicine, agriculture, and other fields. COS were prepared by chitosanase  from Pseudoalteromonas sp. SY39 and their anti-obesity activity was researched in mice in this study. The effects of hydrolysis time, temperature, the ratio of enzyme to chitosan, and pH on the productivity of COS were discussed. Preparation process of COS was established in a 5-L fermenter. COS were characterized and their anti-obesity activity was studied in animal experiments. The results showed that COS could effectively reduce serum lipid levels and obesity in mice, and have a good anti-obesity activity. The preparation technology and remarkable anti-obesity activity of COS further expand their applications in the food and pharmaceutical industries.

Combating atherosclerosis with targeted Diosmin nanoparticles-treated experimental diabetes.

Diabetes with poor glycemic control is accompanying with an increased risk of disease namely atherosclerotic cardiovascular. Diosmin (DSN), which is obtained from citrus fruit used to assist the treatment of hemorrhoids or chronic venous atherosclerosis diseases, has an antioxidant, anti-hyperglycemic and anti-inflammatory effect. DSN is characterized by poor water solubility which limits its absorption by the gastrointestinal tract. To overcome this limitation, this study was designed to increase DSN bioavailability and solubility, through its loading on polymeric matrix; hydroxypropyl starch (HPS) and Poly lactide-glycolide-chitin (PLGA/chitin) to prepare Diosmin nanoparticles (DSN-NPs). Two methods were used to prepare DSN- NPs; Emulsion-solvent evaporation and Acid-base neutralization followed by further assessment on diabetes induced atherosclerosis The study was conducted on 50 animals assigned into 5 groups with 10 animals in each group: Group I: Normal rats received only normal saline, Group II: Diabetic rats, Group III: diabetic rats received oral DSN, Group IV: diabetic rats received DSN loaded HPS, Group V: diabetic rats received DSN loaded PLGA/chitin. Levels of total cholesterol, triglycerides, HDL-cholesterol, insulin, MDA and NO. plasminogen activator inhibitor-1 PAI-1), Paraoxonase-1(PON1), transforming growth factor-ß1 (TGF-ß1), NF-Ò¡B and Ang II were estimated. Our study revealed that, there was statistically significant difference between DSN treated group compared with DSN loaded HPS treated group and DSN loaded PLGA/chitin. Furthermore, the results obtained clearly disclosed no statistically significant difference between DSN loaded PLGA/chitin and control group exhibited DSN loaded PLGA/chitin has the higher ability to counteract the atherosclerosis factors induced by diabetes in all rats.

Co-administration of chitin micro-particle and Leishmania antigen proposed a new immune adjuvant against experimental leishmaniasis.

AIMS: We investigated the protective effect of chitin micro-particle (CMP) as an adjuvant against Leishmania infection in BALB/c mice. METHODS: Mice were immunized subcutaneously with soluble Leishmania antigen (SLA) plus CMP (100 µg SLA + 100 µg CMP/100 µL) as the test group. Three weeks after the last immunization, test and control groups were infected by Leishmania major (L major). Eight weeks post-infection, evaluation of parasites load in lymph nodes was performed using limiting dilution assay. Then, the spleen cell cytokine response (TNF-α, IFN-γ, IL-4, IL-10, IL-17 and IL-27) to SLA among vaccinated and nonvaccinated groups was investigated using ELISA. Serum levels of IgG1 and IgG2a were measured as well. RESULTS: The SLA plus CMP group demonstrated the protection. The responses included reduced lesion formation and lower parasite load. Also, in comparison with control group higher levels of IFN-γ and, IL-10 in the culture of spleen cells, and lower levels of IgG1 in sera were seen in SLA plus CMP group. CONCLUSION: The data supported the possibility of using CMP as a suitable adjuvant in Leishmania vaccination.

Therapeutic Effect of Chitooligosaccharide Tablets on Lipids in High-Fat Diets Induced Hyperlipidemic Rats.

Chitooligosaccharide is beneficial for inhibiting dyslipidemia and reducing atherosclerotic and hyperlipidemic risk. The purpose of this study was to investigate the cholesterol-regulating effects and potential mechanisms of Chitooligosaccharide tablets (CFTs) in high-fat diet-induced hyperlipidemic rats. The results revealed that CFTs can regulate serum lipid levels in hyperlipidemic rats in a dosage-dependent manner. Synchronously, gene expressions related to cholesterol excretion were upregulated in a dosage-dependent manner, including cholesterol 7α-hydroxylase (CYP7A1), liver X receptor α (LXRA), peroxisome proliferation-activated receptor-α (PPARα) and low-density lipoprotein receptor (LDLR), whereas cholesterol synthetic gene expressions including 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) and sterol-responsive element binding protein-2 (SREBP2) were reduced. This work highlights that CFTs have potential as natural products to prevent and treat metabolic hyperlipidemia syndrome, probably due to the reduction of cholesterol biosynthesis and through cholesterol elimination; they also improve the pathological changes of liver tissue in rats, alleviate liver damage, maintain normal lipid metabolism in the liver, ameliorate hepatic glycolipid disorders and accelerate TC operation, and reduce blood lipid levels.

Effects of palygorskite composites on growth performance and antioxidant status in broiler chickens.

This work aimed to investigate the effects of the palygorskite (PAL) composites on the growth performance and antioxidant status in broiler chickens. A total of 192 one-day-old Ross 308 broilers were randomly divided into 3 treatment groups. Broilers were fed basal diets supplemented with either 50 mg/kg chlortetracycline (CTC group), 1 g/kg ZnO/PAL (ZnO/PAL group), or 1 g/kg chitooligosaccharides/ZnO/PAL (COS/ZnO/PAL group), respectively. The results showed that PAL composites were found to exhibit similar effects on growth performance as CTC (P > 0.05). ZnO/PAL and COS/ZnO/PAL enhanced the activity of serum glutathione peroxidase (GSH-Px) compared with CTC both at 21 and 42 d (P < 0.05). Compared with the CTC group, COS/ZnO/PAL enhanced serum catalase (CAT) activity at 21 d (P < 0.05), and decreased serum malondialdehyde (MDA) content at 42 d (P < 0.05). Compared with the CTC group, ZnO/PAL decreased duodenal mucous MDA content at 21 d, while ZnO/PAL did not affect activities of superoxide dismutase (SOD) and GSH-Px in the duodenum (P > 0.05). The duodenal mucous activities of SOD and GSH-Px were the highest in the COS/ZnO/PAL group at 42 d (P < 0.05). At 21 d, broilers in the COS/ZnO/PAL group had the lowest MDA content and the highest total antioxidant capacity (T-AOC) in the jejunum (P < 0.05). Palygorskite composites decreased ileum mucous MDA content compared with CTC treated broilers at 21 d (P < 0.05). At 42 d, ileum mucous T-AOC was increased both in the ZnO/PAL and COS/ZnO/PAL groups compared with the CTC group (P < 0.05). The ileum mucous GSH-Px activities both in the ZnO/PAL and COS/ZnO/PAL groups were increased compared with the CTC group (P < 0.05). In conclusion, the broilers given the basal diet supplemented with the PAL composites exhibited similar growth performance to their counterparts in the AGP group. Additionally, the PAL composites improved the antioxidant status of broilers and the beneficial effects of COS/ZnO/PAL on the antioxidant status are more pronounced.

Gut health and serum growth hormone levels of broiler chickens fed dietary chitin and chitosan from cricket and shrimp.

Growth hormones (GH) alone does not explain the growth rate in the chicken as growth in an animal is multi-factorial. Normal morphology of the intestinal villus and crypt, with adequate regulation of intestinal nutrient transporters, is essential to a healthy gut. Nutrition plays a significant role in gut health management, but information on the effect of dietary chitin and chitosan on gut morphology, gene expression of nutrient transporter, and serum levels of GH in broiler chickens is scanty. Thus, this study aimed at evaluating the comparative effect of dietary chitin and chitosan from cricket and shrimp on the small intestinal morphology, relative gene expression of intestinal nutrient transporters and serum level of GH in the broiler. A total of 150 day-old male Cobb500 broiler chicks were randomly allotted to one of the five treatment groups (n = 30). Treatment 1 was fed basal diet only, treatments 2 to 5 were fed a basal diet with 0.5 g cricket chitin, cricket chitosan, shrimp chitin, and shrimp chitosan, respectively, per kg diet. At days 21 and 42, duodenal and jejunal samples were assessed for structural morphology and jejunum for the relative gene expression of PepT1, EAAT3, SGLT1, and SGLT5 using quantitative real-time PCR. Results bared that dietary cricket chitosan and shrimp chitosan significantly (P < 0.05) improved jejunal villus height and reduced crypt depth without improving the body weight (BW). The gut morphology of birds under cricket chitin was poor and significantly (P < 0.05) different from other treated groups. Both the dietary chitin and chitosan at day 21 and only dietary chitosan at day 42 significantly (P < 0.05) down-regulated the relative mRNA expression of PepT1, EAAT3, SGLT1, and SGLT5 of broiler chickens. Treated groups differ non-significantly at both phases, while cricket chitin numerically increased the relative expression of PepT1, EAAT3, and SGLT1. Therefore, the potential of cricket chitin to improve BW and to up-regulate nutrient transporters is worthy of further exploration.

A novel antibacterial agent based on AgNPs and Fe3O4 loaded chitin microspheres with peroxidase-like activity for synergistic antibacterial activity and wound-healing.

In this study, a novel antibacterial agent was developed based on chitin nanofibrous microspheres loaded with AgNPs and Fe3O4 nanoparticles (Ag-Fe3O4-NMs) for synergistic antibacterial activity and wound healing. Ag-Fe3O4-NMs was prepared via an in situ synthetic method which showed an excellent porosity and wettability. Moreover, Ag-Fe3O4-NMs were capable of sustained release of Ag+ and catalysed the decomposition of low H2O2 concentrations to generate hydroxyl radical (OH). The OH and Ag+ showed higher antibacterial activity and inhibited the toxicity with high dose of AgNPs and H2O2. In vitro biocompatibility results suggested that Ag-Fe3O4-NMs have low toxicity and low hemolysis. Thus, a novel antibacterial agent with enhanced synergistic antibacterial activity was obtained by combination of Ag-Fe3O4-NMs and H2O2 at a low and biologlically safe dosage, which could facilitate fibroblast growth, accelerate epithelialization, and promote the healing rate of infected wounds.

Preparation of N-succinyl-chitin nanoparticles and their applications in otoneurological pathology.

Succinyl-chitin (SCH) nanoparticles were obtained by acylation of partially deacetylated chitin (DCH) nanofibers. Introduction of the succinyl moiety induced a partial amorphization of DCH, as viewed by X-ray diffraction, and increased the fractal dimension of the colloids from df = 1.2 (DCH) to 1.5-1.7 (SCH), as revealed by light scattering. The spherically symmetric form of the colloids remained almost unchanged, as indicated by the range of structure-sensitive ratios 1.0 < Rg/Rh < 1.2; the hydrodynamic diameter ranged from 200 to 300 nm. The cytoprotective activity of the SCH nanoparticles was evaluated in vivo in an acute hearing pathology model (220-250 g male Wistar rats, n = 90) following prophylactic and therapeutic administrations. Ototropic action was estimated using the amplitude of otoacoustic emissions at the frequency of the distortion product otoacoustic emissions in the range of 4-6.4 kHz before acoustic stimulation, as well as at 1 h, 24 h, and 7 days after acoustic stimulation. A dispersion of 0.3% SCH nanoparticles demonstrated prolonged ototropic action and earlier regeneration of hearing functions when compared to a meglumine sodium succinate solution. Thus, intravenous administration of the SCH nanoparticles increases the cycling time of exogenous succinate and improves biodistribution in tissues possessing a hemato-labyrinth barrier.

Glucan-Chitin Particles Enhance Th17 Response and Improve Protective Efficacy of a Multivalent Antigen (rCpa1) against Pulmonary Coccidioides posadasii Infection.

Developing an effective and safe recombinant vaccine requires microbe-specific antigens combined with an adjuvant/delivery system to strengthen protective immunity. In this study, we designed and expressed a multivalent recombinant Coccidioides polypeptide antigen (rCpa1) that consists of three previously identified antigens (i.e., Ag2/Pra, Cs-Ag, and Pmp1) and five pathogen-derived peptides with high affinity for human major histocompatibility complex class II (MHC-II) molecules. The purified rCpa1 was encapsulated into four types of yeast cell wall particles containing ß-glucan, mannan, and chitin in various proportions or was mixed with an oligonucleotide (ODN) containing two methylated dinucleotide CpG motifs. This multivalent antigen encapsulated into glucan-chitin particles (GCP-rCpa1) showed significantly greater reduction of fungal burden for human HLA-DR4 transgenic mice than the other adjuvant-rCpa1 formulations tested. Among the adjuvants tested, both GCPs and ß-glucan particles (GPs) were capable of stimulating a mixed Th1 and Th17 response. Mice vaccinated with GCP-rCpa1 showed higher levels of interleukin 17 (IL-17) production in T-cell recall assays and earlier lung infiltration by activated Th1 and Th17 cells than GP-rCpa1-vaccinated mice. Both C57BL/6 and HLA-DR4 transgenic mice that were vaccinated with the GCP-rCpa1 vaccine showed higher survival rates than mice that received GCPs alone. Concurrently, the GCP-rCpa1 vaccine stimulated greater infiltration of the injection sites by macrophages, which engulf and process the vaccine for antigen presentation, than the GP-rCpa1 vaccine. This is the first attempt to systematically characterize the presentation of a multivalent coccidioidomycosis vaccine encapsulated with selected adjuvants that enhance the protective cellular immune response to infection.

Chitin Oligosaccharide Modulates Gut Microbiota and Attenuates High-Fat-Diet-Induced Metabolic Syndrome in Mice.

Gut microbiota has been proved to be an indispensable link between nutrient excess and metabolic syndrome, and chitin oligosaccharide (NACOS) has displayed therapeutic effects on multiple diseases such as cancer and gastritis. In this study, we aim to confirm whether NACOS can ameliorate high-fat diet (HFD)-induced metabolic syndrome by rebuilding the structure of the gut microbiota community. Male C57BL/6J mice fed with HFD were treated with NACOS (1 mg/mL) in drinking water for five months. The results indicate that NACOS improved glucose metabolic disorder in HFD-fed mice and suppressed mRNA expression of the protein regulators related to lipogenesis, gluconeogenesis, adipocyte differentiation, and inflammation in adipose tissues. Additionally, NACOS inhibited the destruction of the gut barrier in HFD-treated mice. Furthermore, 16S ribosome RNA sequencing of fecal samples demonstrates that NACOS promoted the growth of beneficial intestinal bacteria remarkably and decreased the abundance of inflammogenic taxa. In summary, NACOS partly rebuilt the microbial community and improved the metabolic syndrome of HFD-fed mice. These data confirm the preventive effects of NACOS on nutrient excess-related metabolic diseases.

Surfactant-stable and pH-sensitive liposomes coated with N-succinyl-chitosan and chitooligosaccharide for delivery of quercetin.

Layer-by-layer (LbL) self-assembly of multilayered liposomes is used to improve the stability of conventional liposomes. In this study, the LbL technology was used to prepare novel multilayered liposomes from chitooligosaccharide and N-succinyl-chitosan. We propose that this preparation can be used as a transdermal drug delivery system (TDDS) to enhance stability against surfactants and control drug release. Particle size increased with the number of layers in the multilayer and the zeta potential varied between positive and negative values with alternate deposition of polyelectrolytes. Finally, approximately 300-400nm-thick four-layered liposomes were prepared. These liposomes were more stable against surfactants and showed a relatively high release of quercetin at pH 5.5 than the uncoated liposomes as assessed via in vitro drug release and skin permeation studies. In summary, the multilayered liposomes showed potential for use as a surfactant-stable TDDS that effectively enhanced the permeation of quercetin, a poorly soluble drug, into the skin.

An oral absorbent, surface-deacetylated chitin nano-fiber ameliorates renal injury and oxidative stress in 5/6 nephrectomized rats.

In this study, we report that surface-deacetylated chitin nano-fibers (SDACNFs) are more effective in decreasing renal injury and oxidative stress than deacetylated chitin powder (DAC) in 5/6 nephrectomized rats. An oral administration of low doses of SDACNFs (40mg/kg/day) over a 4 week period resulted in a significant decrease in serum indoxyl sulfate, creatinine and urea nitrogen levels, compared with a similar treatment with DAC or AST-120. The SDACNFs treatment also resulted in an increase in antioxidant potential, compared with that for DAC or AST-120. Immunohistochemical analyses also demonstrated that SDACNFs treated CRF rats showed a decrease in the amount of accumulated 8-OHdG compared with the CRF group. These results suggest that the ingestion of SDCH-NF results in a significant reduction in the levels of pro-oxidants, such as uremic toxins, in the gastrointestinal tract, thereby inhibiting the subsequent development of oxidative stress in the systemic circulation.

Oral Administration of Surface-Deacetylated Chitin Nanofibers and Chitosan Inhibit 5-Fluorouracil-Induced Intestinal Mucositis in Mice.

This study investigated the prophylactic effects of orally administered surface-deacetylated chitin nanofibers (SDACNFs) and chitosan against 5-fluorouracil (5-FU)-induced intestinal mucositis, which is a common side effect of 5-FU chemotherapy. SDACNFs and chitosan abolished histological abnormalities associated with intestinal mucositis and suppressed hypoproliferation and apoptosis of intestinal crypt cells. These results indicate that SDACNF and chitosan are useful agents for preventing mucositis induced by anti-cancer drugs.

Comparative anti-psoriatic efficacy studies of clobetasol loaded chitin nanogel and marketed cream.

In the present study chitin nanogel loaded with anti-psoriatic drug clobetasol was developed (CLCNG) for its topical delivery in psoriasis. CLCNG had the particle size of 132±14nm, with gel like consistency, stability in refrigerator, having higher drug release properties at acidic pH. CLCNG exhibited significant toxicity towards HaCaT and THP-1cell lines by MTT assay. The uptake of nanogel by HaCaT cell lines was confirmed by fluorescent microscopy. CLCNG at 0.35mg/ml exhibited significant anti-inflammatory activity with an average of 65% and 70% inhibition in COX and LOX activities expressed in THP-1 cells. In vitro skin permeation studies revealed the increased transdermal flux with fragmented stratum corneum and loosened epidermal layers in CLCNG treated samples, compared with control drug solution. The in vivo anti-psoriatic studies done on imiquimod model confirmed the potential benefits of the nanogel for the topical delivery of clobetasol in psoriasis.