Inulin with different degrees of polymerization protects against diet-induced endotoxemia and inflammation in association with gut microbiota regulation in mice

Societal lifestyle changes, especially increased consumption of a high-fat diet lacking dietary fibers, lead to gut microbiota dysbiosis and enhance the incidence of adiposity and chronic inflammatory disease. We aimed to investigate the metabolic effects of inulin with different degrees of polymerization on high-fat diet-fed C57BL/6 J mice and to evaluate whether different health outcomes are related to regulation of the gut microbiota. Short-chain and long-chain inulins exert beneficial effects through alleviating endotoxemia and inflammation. Antiinflammation was associated with a proportional increase in short-chain fatty acid-producing bacteria and an increase in the concentration of short-chain fatty acids. Inulin might decrease endotoxemia by increasing the proportion of Bifidobacterium and Lactobacillus, and their inhibition of endotoxin secretion may also contribute to antiinflammation. Interestingly, the beneficial health effects of long-chain inulin were more pronounced than those of short-chain inulin. Long-chain inulin was more dependent than short-chain inulin on species capable of processing complex polysaccharides, such as Bacteroides. A good understanding of inulin-gut microbiota-host interactions helps to provide a dietary strategy that could target and prevent high-fat diet-induced endotoxemia and inflammation through a prebiotic effect.

Gut Microbiota Modulation on Intestinal Mucosal Adaptive Immunity

The mammalian intestine harbors a remarkable number of microbes and their components and metabolites, which are fundamental for the instigation and development of the host immune system. The intestinal innate and adaptive immunity coordinate and interact with the symbionts contributing to the intestinal homeostasis through establishment of a mutually beneficial relationship by tolerating to symbiotic microbiota and retaining the ability to exert proinflammatory response towards invasive pathogens. Imbalance between the intestinal immune system and commensal organisms disrupts the intestinal microbiological homeostasis, leading to microbiota dysbiosis, compromised integrity of the intestinal barrier, and proinflammatory immune responses towards symbionts. This, in turn, exacerbates the degree of the imbalance. Intestinal adaptive immunity plays a critical role in maintaining immune tolerance towards symbionts and the integrity of intestinal barrier, while the innate immune system regulates the adaptive immune responses to intestinal commensal bacteria. In this review, we will summarize recent findings on the effects and mechanisms of gut microbiota on intestinal adaptive immunity and the plasticity of several immune cells under diverse microenvironmental settings.

Dietary butyrate suppresses inflammation through modulating gut microbiota in high-fat diet-fed mice

Butyrate, a key metabolite fermented by gut microbiota mainly from undigested carbohydrates such as dietary fibers is widely used as feed additive. However, mechanisms of its contributions in maintaining host health are relatively poorly revealed. The aim of this study was to investigate how butyrate impacts gut microbiota and immunity response in high-fat diet-fed mice. Gut microbial analysis exhibited that butyrate intervention increased short-chain fatty acids (SCFAs)-producing bacteria and decreased pathogenic bacteria, such as endotoxin-secreting bacteria. Our result also demonstrated that butyrate intervention enhanced fecal SCFAs concentrations, and inhibited endotoxin levels in feces and serum. Correlation analysis indicated positive relation between endotoxin level and Desulfovibrionaceae abundance. Furthermore, butyrate intervention inhibited expressions of IL-1β, IL-6 and MCP1/CCL2 in liver, as well as TLR4 in adipose tissue. Apart from inhibiting expressions of proinflammatory cytokines, butyrate exerted anti-inflammation effect through selectively modulating gut microbiota, such as increasing SCFAs-producing bacteria and decreasing endotoxin-secreting bacteria, as well as via regulating levels of microbiota-dependent metabolites and components, such as SCFAs and endotoxin.

Inulin with different degrees of polymerization modulates composition of intestinal microbiota in mice

The study aimed to analyze the global influences of dietary inulin with different degrees of polymerization (DP) on intestinal microbial communities. Six-week-old male C57BL/6J mice were treated with fructo-oligosaccharides and inulin for 6 weeks. Fecal samples were obtained at time point 0 and 6th week. 16S rRNA sequence analysis was used to measure intestinal microbiota performed on the Illumina MiSeq platform. Influences of dietary inulin on intestinal microbiota were more complex effects than bifidogenic effects, relative abundance of butyrate-producing bacteria increased after interventions. Akkermansia muciniphila, belonging to mucin-degrading species, became a dominant species in Verrucomicrobia phylum after treatment with fructo-oligosaccharides and inulin. Modulation effects of intestinal microbiota were positively correlated with DP. Lower DP interventions exhibited better effects than higher DP treatment on stimulation of probiotics. We hypothesized that Akkermansia muciniphila played an important role on maintaining balance between mucin and short chain fatty acids.

Effect of lactulose intervention on gut microbiota and short chain fatty acid composition of C57BL/6J mice

Gut microbiota have strong connections with health. Lactulose has been shown to regulate gut microbiota and benefit host health. In this study, the effect of short-term (3 week) intervention of lactulose on gut microbiota was investigated. Gut microbiota were detected from mouse feces by 16S rRNA high-throughput sequencing, and short chain fatty acids (SCFAs) were detected by gas chromatography-mass spectrometry (GC-MS). Lactulose intervention enhanced the α-diversity of the gut microbiota; increased the abundance of hydrogen-producing bacteria Prevotellaceae and Rikenellaceae, probiotics Bifidobacteriaceae and Lactobacillaceae, and mucin-degrading bacteria Akkermansia and Helicobacter; decreased the abundance of harmful bacteria Desulfovibrionaceae and branched-chain SCFAs (BCFAs). These results suggest that lactulose intervention effectively increased the diversity and improved the structure of the intestinal microbiota, which may be beneficial for host health.

Responsively Degradable Nanoarmor-Assisted Super Resistance and Stable Colonization of Probiotics for Enhanced Inflammation-Targeted Delivery

Manipulation of the gut microbiota using oral microecological preparations has shown great promise in treating various inflammatory disorders. However, delivering these preparations while maintaining their disease-site specificity, stability, and therapeutic efficacy is highly challenging due to the dynamic changes associated with pathological microenvironments in the gastrointestinal tract. Herein, a superior armored probiotic with an inflammation-targeting capacity is developed to enhance the efficacy and timely action of bacterial therapy against inflammatory bowel disease (IBD). The coating strategy exhibits suitability for diverse probiotic strains and has negligible influence on bacterial viability. This study demonstrates that these armored probiotics have ultraresistance to extreme intraluminal conditions and stable mucoadhesive capacity. Notably, the HA-functionalized nanoarmor equips the probiotics with inflamed-site targetability through multiple interactions, thus enhancing their efficacy in IBD therapy. Moreover, timely "awakening" of ingested probiotics through the responsive transferrin-directed degradation of the nanoarmor at the site of inflammation is highly beneficial for bacterial therapy, which requires the bacterial cells to be fully functional. Given its easy preparation and favorable biocompatibility, the developed single-cell coating approach provides an effective strategy for the advanced delivery of probiotics for biomedical applications at the cellular level.

Effects of phycocyanin in modulating the intestinal microbiota of mice

The health-promoting effects of phycocyanin (PC) have become widely accepted over the last two decades. In this study, we investigated the effects of different doses of PC in modulating the intestinal microbiota and the intestinal barrier in mice. Six-week-old male C57BL/6 mice were treated with PC for 28 days. Fecal samples were collected before and after PC intervention, and the microbiota were analyzed by 16S rRNA high-throughput sequencing. Bacterial abundance and diversity increased after PC intervention. Saccharolytic bacteria of the families Lachnospiraceae and Ruminococcaceae, which can produce butyric acid, increased after PC treatment. The family Rikenellaceae, which contains hydrogen-producing bacteria, also increased after PC intervention. The PC treatment reduced intestinal permeability and increased the intestinal barrier function, as demonstrated by hematoxylin-eosin staining and reduced serum lipopolysaccharide levels. The modulating effects on the intestinal microbiota were more favorable in the low-dose PC group.

Blood-Brain Barrier Permeable Chitosan Oligosaccharides Interfere with β-Amyloid Aggregation and Alleviate β-Amyloid Protein Mediated Neurotoxicity and Neuroinflammation in a Dose- and Degree of Polymerization-Dependent Manner

It is proven that β-amyloid (Aβ) aggregates containing cross-β-sheet structures led to oxidative stress, neuroinflammation, and neuronal loss via multiple pathways. Therefore, reduction of Aβ neurotoxicity via inhibiting aggregation of Aβ or dissociating toxic Aβ aggregates into nontoxic forms might be effective therapeutic methods for Alzheimer's disease (AD) treatment. This study was designed to explore interference of chitosan oligosaccharides (COS) on β-(1-42)-amyloid protein (Aβ42) aggregation and Aβ42-induced cytotoxicity. Here it was demonstrated that COS showed good blood-brain barrier (BBB) penetration ability in vitro and in vivo. The experimental results showed that COS efficiently interfered with Aβ42 aggregation in dose- and degree of polymerization (DP)-dependent manners, and COS monomer with DP6 showed the best effect on preventing conformational transition into β-sheet-rich structures. Based on the binding affinity analysis by microscale thermophoresis (MST), it was confirmed that COS could directly bind with Aβ42 in a DP-dependent manner. Our findings demonstrated that different performance of COS monomers with different DPs against Aβ42 assembly was, to some extent, attributable to their different binding capacities with Aβ42. As a result, COS significantly ameliorated Aβ42-induced cytotoxicity. Taken together, our studies would point towards a potential role of COS in treatment of AD.

Chitosan Oligosaccharides Regulate the Occurrence and Development of Enteritis in a Human Gut-On-a-Chip

Past studies on the protective effects of chitosan oligosaccharides (COS) on inflammatory bowel disease (IBD) commonly rely on animal models, because traditional cell culture systems couldn't faithfully mimic human intestinal physiology. Here a novel human gut-on-a-chip microsystem was established to further explore the regulatory effects of COS on the occurrence and development of human enteritis. By constructing an intestinal injury model caused by dextran sodium sulfate (DSS) on the chip, this study proved that COS can reduce intestinal epithelial injury by promoting the expression of the mucous layer for the first time. By establishing an inflammatory bowel disease model on the chip caused by E. coli 11775, this study demonstrated that COS can protect the intestinal epithelial barrier and vascular endothelial barrier by inhibiting the adhesion and invasion of E. coli 11775 for the first time. In addition, similar to the results in vivo, COS can decrease the inflammatory response by reducing the expression of toll-like receptor 4 protein and reducing the nuclear DNA binding rate of nuclear factor kappa-B protein on this chip. In summary, COS can be used as a potential drug to treat human IBD and the human gut-on-a-chip would be used as a platform for quick screening drugs to treat human IBD in future.

Facile General Injectable Gelatin/Metal/Tea Polyphenol Double Nanonetworks Remodel Wound Microenvironment and Accelerate Healing

Treating the most widespread complication of diabetes: diabetic wounds poses a significant clinical obstacle due to the intricate nature of wound healing in individuals with diabetes. Here a novel approach is proposed using easily applicable injectable gelatin/metal/tea polyphenol double nanonetworks, which effectively remodel the wound microenvironment and accelerates the healing process. The gelatin(Gel) crosslink with metal ions (Zr4+ ) through the amino acids, imparting advantageous mechanical properties like self-healing, injectability, and adhesion. The nanonetwork's biological functions are further enhanced by incorporating the tea polyphenol metal nanonetwork through in situ doping of the epigallocatechin gallate (EGCG) with great antibacterial, self-healing, antioxidant, and anticancer capabilities. The in vitro and in vivo tests show that this double nanonetworks hydrogel exhibits faster cell migration and favorable anti-inflammatory and antioxidant properties and can greatly reshape the microenvironment of diabetic wounds and accelerate the wound healing rate. In addition, this hydrogel is completely degraded after subcutaneous injection for 7 days, with nondetectable cytotoxicity in H&E staining of major mice organs and the serum level of liver function indicators. Considering the above-mentioned merits of this hydrogel, it is believed that the injectable gelatin/metal/tea polyphenol double nanonetworks have broad biomedical potential, especially in diabetic wound repair and tissue engineering.

High molecular weight chitosan oligosaccharide exhibited antifungal activity by misleading cell wall organization via targeting PHR transglucosidases

The fungal cell wall is an ideal target for the design of antifungal drugs. In this study we used an analog of cell wall polymer, a highly deacetylated high molecular-weight chitosan oligosaccharide (HCOS), to test its effect against pathogenic Candida strains. Results showed that HCOS was successfully incorporated into the dynamic cell wall organization process and exhibited an apparent antifungal activity against both plankton and mature fungal biofilm, by impairing the cell wall integrity. Unexpectedly, mechanistic studies suggested that HCOS exerts its activity by interfering with family members of PHR β-(1,3)-glucanosyl transferases and affecting the connection and assembly of cell wall polysaccharides. Furthermore, HCOS showed great synergistic activity with different fungicides against Candida cells, especially those in biofilm. These findings indicated HCOS has a great potential as an antifungal drug or drug synergist and proposed a novel antifungal strategy with structure-specific oligosaccharides mimicking cell wall polysaccharide fragments.

The effects of phycocyanin on bleomycin-induced pulmonary fibrosis and the intestinal microbiota in C57BL/6 mice

Phycocyanin (PC) is a light-harvesting protein isolated from Spirulina and has health benefits for a range of diseases including pulmonary fibrosis (PF). In this study, a bleomycin-induced pulmonary fibrosis model was used to determine whether PC attenuates PF and modulates the intestinal microbiota. The results showed that PC intervention attenuated the pulmonary fibrosis, demonstrated by hematoxylin-eosin staining (HE), Masson's trichrome staining, and lung dry-wet weight ratio, and PC significantly inhibited the production of interleukin-1 beta (IL-1β), tumor necrosis factor-α (TNF-α), and lipopolysaccharide (LPS). Additionally, intestinal microbiota analysis revealed that PC intervention significantly increased the bacterial diversity and richness. Correlation analysis indicated that 9 families and 17 genes were significantly associated with at least 1 physiological index. And PC intervention significantly decreased the bacteria which is related to inflammation and dramatically increased the SCFAs-producing bacteria and probiotics. These data indicated that PC can decrease the pro-inflammatory cytokines and regulate the intestinal microbiota in BLM-induced PF mice.

Hydrazone-Based Amphiphilic Brush Polymer for Fast Endocytosis and ROS-Active Drug Release

Due to the high reactivity of reactive oxygen species (ROS), it is essential to sweep them away in time. In this study, ClO--responsible amphiphilic brush polymers were prepared by free radical polymerization using two monomers consisting of polyethylene glycol as the hydrophilic part, and an alkyl chain connected by hydrazone as the hydrophobic part. The macromolecules assemble into particles with nanoscaled dimensions in a neutral buffer, which ensures quick cellular internalization. The polymer has a low critical micellization concentration and can encapsulate hydrophobic drug molecules up to 19% wt. The micelles formed by the polymer disassemble in a ClO--rich environment and release 80% of their cargo within 2 h, which possesses a faster release rate compared to the previous systems. The relatively small size and the quick response of hydrazone toward ClO- ensure a quick uptake and elimination of ROS in vitro and in vivo.

Sustained release of 5-aminosalicylic acid from azoreductase-responsive polymeric prodrugs for prolonged colon-targeted colitis therapy

Ulcerative colitis (UC) is a challenging inflammatory gastrointestinal disorder, whose therapies encounter limitations in overcoming insufficient colonic retention and rapid systemic clearance. In this study, we report an innovative polymeric prodrug nanoformulation for targeted UC treatment through sustained 5-aminosalicylic acid (5-ASA) delivery. Amphiphilic polymer-based 13.5 nm micelles were engineered to incorporate azo-linked 5-ASA prodrug motifs, enabling cleavage via colonic azoreductases. In vitro, micelles exhibited excellent stability under gastric/intestinal conditions while demonstrating controlled 5-ASA release over 24 h in colonic fluids. Orally administered micelles revealed prolonged 24-h retention and a high accumulation within inflamed murine colonic tissue. At an approximately 60% dose reduction from those most advanced recent studies, the platform halted DSS colitis progression and outperformed standard 5-ASA therapy through a 77-97% suppression of inflammatory markers. Histological analysis confirmed intact colon morphology and restored barrier protein expression. This integrated prodrug nanoformulation addresses limitations in colon-targeted UC therapy through localized bioactivation and tailored pharmacokinetics, suggesting the potential of nanotechnology-guided precision delivery to transform disease management.

Variations in metabolic enzymes cause differential changes of heparan sulfate and hyaluronan in high glucose treated cells on chip

Glycocalyx dysfunction is believed as the first step in diabetic vascular disease. However, few studies have systematically investigated the influence of HG on the glycocalyx as a whole and its major constituent glycans towards one type of cell. Furthermore, most studies utilized traditional two-dimensional (2D) cultures in vitro, which can't provide the necessary fluid environment for glycocalyx. Here, we utilized vascular glycocalyx on chips to evaluate the changes of glycocalyx and its constituent glycans in HG induced HUVECs. Fluorescence microscopy showed up-regulation of hyaluronan (HA) but down-regulation of heparan sulfate (HS). By analyzing the metabolic enzymes of both glycans, a decrease in the ratio of synthetic/degradative enzymes for HA and an increase in that for HS were demonstrated. Two substrates (UDP-GlcNAc, UDP-GlcA) for the synthesis of both glycans were increased according to omics analysis. Since they were firstly pumped into Golgi apparatus to synthesize HS, less substrates may be left for HA synthesis. Furthermore, the differential changes of HA and HS were confirmed in vessel slides from db/db mice. This study would deepen our understanding of impact of HG on glycocalyx formation and diabetic vascular disease.