A type 2 immune circuit in the stomach controls mammalian adaptation to dietary chitin

Edible hydrogel with dual network structure for weight management

Obesity, a global health crisis, is fueled by shifts in behavior and environmental factors, notably increased consumption of energy-dense processed foods and inadequate dietary fiber. Traditional weight loss methods pose safety challenges. Sodium carboxymethylcellulose (CMC), a promising dietary fiber supplement, aids weight management. However, CMC-based hydrogels have mechanical weaknesses and poor gastrointestinal retention. A new dual-network structured hydrogel here was introduced to address these issues, maintaining volume and elasticity in the digestive system without adding calories, reducing caloric density, and enhancing food elasticity for prolonged satiety. The study assessed four distinct hydrogels, analyzing their mechanical characteristics under simulated gastrointestinal conditions and biomimetic digestion to identify promising options for clinical development. This dual-network hydrogel exhibits a mechanical strength up to 100 times that of the original gel, while its swelling rate throughout the digestion process is approximately twice that of the original gel. This offers a potential solution for obesity management, providing sustained satiety and addressing the mechanical deficiencies of current hydrogels within the digestive system.

Functional fractions of Astragalus polysaccharides as a potential prebiotic to alleviate ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the intestine that is significantly influenced by an imbalance in the gut microbiota. Astragalus membranaceus, particularly its polysaccharide components, has shown therapeutic potential for the treatment of UC, although the specific active constituents and their mechanistic pathways remain to be fully elucidated. In this study, we investigated two molecular weight fractions of Astragalus polysaccharides (APS), APS1 (Mw < 10 kDa) and APS2 (10 kDa < Mw < 50 kDa), isolated by ultrafiltration, focusing on their prebiotic effects, effects on UC, and the underlying mechanism. Our results showed that both APS1 and APS2 exhibit prebiotic properties, with APS1 significantly outperforming APS2 in ameliorating UC symptoms. APS1 significantly attenuated weight loss and UC manifestations, reduced colonic pathology, and improved intestinal mucosal barrier integrity. In addition, APS1 significantly reduced the levels of inflammatory cytokines in the serum and colonic tissue, and downregulated colonic chemokines. Furthermore, APS1 ameliorated dextran sulfate sodium salt (DSS)-induced intestinal dysbiosis by promoting the growth of beneficial microbes and inhibiting the proliferation of potential pathogens, leading to a significant increase in short-chain fatty acids. In conclusion, this study highlights the potential of APS1 as a novel prebiotic for the prevention and treatment of UC.

Effect of chitin-architected spatiotemporal three-dimensional culture microenvironments on human umbilical cord-derived mesenchymal stem cells

Mesenchymal stem cell (MSC) transplantation has been explored for the clinical treatment of various diseases. However, the current two-dimensional (2D) culture method lacks a natural spatial microenvironment in vitro. This limitation restricts the stable establishment and adaptive maintenance of MSC stemness. Using natural polymers with biocompatibility for constructing stereoscopic MSC microenvironments may have significant application potential. This study used chitin-based nanoscaffolds to establish a novel MSC three-dimensional (3D) culture. We compared 2D and 3D cultured human umbilical cord-derived MSCs (UCMSCs), including differentiation assays, cell markers, proliferation, and angiogenesis. When UCMSCs are in 3D culture, they can differentiate into bone, cartilage, and fat. In 3D culture condition, cell proliferation is enhanced, accompanied by an elevation in the secretion of paracrine factors, including vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), Interleukin-6 (IL-6), and Interleukin-8 (IL-8) by UCMSCs. Additionally, a 3D culture environment promotes angiogenesis and duct formation with HUVECs (Human Umbilical Vein Endothelial Cells), showing greater luminal area, total length, and branching points of tubule formation than a 2D culture. MSCs cultured in a 3D environment exhibit enhanced undifferentiated, as well as higher cell activity, making them a promising candidate for regenerative medicine and therapeutic applications.

Synthesis, characterization and antifungal properties of maleopimaric anhydride modified chitosan

Fruit spoilage can cause huge economic losses, in which fungal infection is one of the main influencing factors, how to effectively control mould and spoilage of fruits and prolong their shelf-life has become a primary issue in the development of fruit and vegetable industry. In this study, rosin derivative maleopimaric anhydride (MPA) was combined with biodegradable and antifungal chitosan (CS) to enhance its antifungal and preservative properties. The modified compounds were characterized by FTIR, 1H NMR spectra and XRD, and the in vitro antifungal properties of the modified compounds were evaluated by the radial growth assay and the minimal inhibitory concentration assay. The preservation effect on small mandarin oranges and longan was studied. The analysis revealed that the modification product (CSMA) of MPA access to C6-OH of CS had a better antifungal effect. In addition, CSMA was more environmentally friendly and healthier than the commercially available chemical preservative (Imazalil), and had the same antifungal preservative effect in preserving small mandarin orange, and was able to extend the shelf life to >24 d. In the preservation of longan, CSMA was more effective against tissue water loss and was able to maintain the moisture in the longan pulp and extend the shelf life. Therefore, CSMA has good application potentials in longan keeping-fresh.

Synthesis, characterization and antifungal properties of dehydroabietic acid modified chitosan

The bioactivities of pristine chitosan are considerable weak compared with the commercial chemicals, which has restricted its broad application prospects in food packaging and preservation. In order to obtain a safe, biologically derived fruits preservative with excellent antifungal properties, dehydroabietic acid (DHA) was used to modify chitosan (CS). The structural characterization of modified chitosans were identified by FTIR and 1H NMR spectra. The XRD pattern showed the modified chitosan changed the crystal structure due to the modification of the amino and/or hydroxyl groups on the chitosan. Their antifungal activities against Penicillium digitutim and Penicillium italicum were investigated in vitro using the radial growth assay and the minimal inhibitory concentration assay. The study also examined the differences in antifungal effect among three modified chitosans. The results showed that DHA only conjugated thehydroxyl group at C-6, bearing free amino group at C-2, exhibited the strongest antifungal effect, with a minimum inhibitory concentration (MIC) of 200 μg/mL. In addition, a comparison of the antifungal activity of the modified compounds with different concentrations of Imazalil demonstrated that the modified biologic antifungal agent was as effective as Imazalil. CSDA can achieve 100 % inhibition of P. digitutim at concentrations >100 μg/mL and remain unchanged for a long time. Because CSDA can enhance the shelf life of longans, DHA-CS, chitosan derivatives, have tremendous promise for use in fruits preservation.

Dietary fibers affecting gastrointestinal immunity

Dietary fibers, including chitin, have a major impact on gastrointestinal (GI) physiology and immunity. Two recent articles, by Parrish et al. and Kim et al., credit depletion of dietary fibers or supplementation with chitin, with negative and positive effects, respectively, on the immune system of the murine digestive tract. This has relevant implications for food allergies and systemic metabolism.