Inulin diet uncovers complex diet-microbiota-immune cell interactions remodeling the gut epithelium

Engineered probiotics remodel the intestinal epithelial barrier and enhance bacteriotherapy for inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are often associated with compromised epithelial barriers and dysregulated gut microbiota. In this study, we revealed the synergistic effect that zinc and indole-3-carbinol (I3C) have in restoring the epithelial barrier, and co-localized them on a ZI platform, which was further conjugated to the surface of Escherichia coli Nissle 1917 (EcN). The ZI@EcN formulation effectively delivered ZI to colon tissues and extended its retention in the intestines due to the colonic colonization effect of EcN, thereby promoting the sustained release of zinc and I3C for optimal synergistic effects on epithelial barrier remodeling. The restored epithelium acts as a protective barrier, preventing the infiltration of toxins and pathogens, which significantly reduces inflammation in colonic tissues. Additionally, EcN enriched the gut microbiome, increasing the abundance of beneficial bacteria while reducing that of pathogens, demonstrating its significant efficacy in gut microbiome regulation. In dextran sulfate sodium-induced mouse colitis models, ZI@EcN exhibited substantially improved prophylactic and therapeutic efficacy with favorable safety profiles, highlighting its potential for clinical applications. STATEMENT OF SIGNIFICANCE: This study highlighted the synergistic effects that zinc and indole-3-carbinol, both derived from dietary sources, have on restoring integrity of the intestinal epithelial barrier. A platform (ZI@EcN) was also developed for the targeted delivery and sustained release of zinc and indole-3-carbinol, specifically in colonic tissues, for colitis treatment. This platform not only restores the compromised intestinal epithelial barrier but also regulates the dysbiotic gut microbiota, promoting the recovery of a healthy intestinal microenvironment and showing promise in alleviating complex symptoms in a single formulation. Furthermore, the formulation demonstrated potent prophylactic and therapeutic efficacy against colitis, with favorable safety profiles, and a strong potential for clinical applications.

CaGA nanozymes inhibit oxidative stress and protect mitochondrial function in ulcerative colitis therapy

Ulcerative colitis (UC) is a long-term inflammatory bowel disease characterized by intense inflammation of the colorectal mucosa. Overproduction of reactive oxygen species exacerbates the progression of UC, which is linked to mitochondrial impairment and dysbiosis of the intestinal microbiota. CaGA nanozymes have demonstrated efficacy in the treatment of UC. The modulation of M1 and M2 polarization of macrophages by CaGA nanozymes has been demonstrated to be useful in reducing inflammation. Furthermore, CaGA nanozymes regulate the M1 and M2 polarization of macrophages, efficiently decreasing inflammation. The oral delivery of CaGA nanozymes resulted in their enrichment in inflamed areas of the colon and effectively reduced colonic damage in mice with DSS-induced colitis by improving the repair of the intestinal barrier. An investigation of 16S rDNA sequencing revealed that CaGA nanozymes regulate populations of both pathogenic and helpful bacteria and impact the progression of ulcerative colitis by influencing the tricarboxylic acid (TCA) cycle. Thus, CaGA nanozymes may be employed in the management of ulcerative colitis to control the intestinal milieu and improve the preservation of the intestinal barrier by decreasing the invasion of inflammatory cells and restoring mitochondrial activity. STATEMENT OF SIGNIFICANCE: CaGA nanozymes exhibit multifunctional enzymatic activity, effectively eliminating cellular RONS with robust antioxidant capacity. CaGA nanoenzymes promote macrophage M1 to M2 polarization and produce anti-inflammatory effects. CaGA nanozymes increase cell viability by restoring impaired mitochondrial function, reducing reactive oxygen species (ROS) production, and restoring the ability of mitochondria to produce ATP. CaGA nanozymes modulate intestinal flora diversity and composition, potentially influencing inflammatory pathways via aromatic compound metabolism. They participate in cellular energy and biosynthesis, regulating ulcerative colitis (UC)-related intestinal function through the tricarboxylic acid (TCA) and urea cycles. Calcium ions bind to GA nanomedicine and small particles are readily absorbed by inflammatory cells, preventing diarrhea from being rapidly excreted.

Inflammatory Microenvironment-Responsive Microsphere Vehicles Modulating Gut Microbiota and Intestinal Inflammation for Intestinal Stem Cell Niche Remodeling in Inflammatory Bowel Disease

Intestinal stem cells (ISCs) engage in proliferation to maintain a stable stem cell population and differentiate into functional epithelial subpopulations. This intricate process is upheld by various signals derived from the host and gut microbiota, establishing an ISC niche. However, during inflammatory bowel disease (IBD), this signaling niche undergoes dramatic changes, leading to impaired ISC and hindered restoration of the damaged intestinal epithelial barrier. This study introduces intestinal inflammatory microenvironment-responsive microsphere vehicles designed to remodel the ISC niche, offering an approach to treat IBD. Using an advanced emulsion technique, these microsphere vehicles specifically target colonic inflammation sites, delivering a responsive release of MXene and l-arginine. This delivery system is formulated to modulate intestinal flora and immune responses effectively. l-arginine is converted into nitric oxide to regulate the gut microbiome, while MXene serves as a nanoimmunomodulator to stabilize immune homeostasis. Our findings demonstrate that the anti-inflammatory properties of the microspheres are key to promoting epithelial repair and remodeling of the ISC niche. This study highlights the role of antioxidant microspheres as anti-inflammatory agents that indirectly support ISC function and gut regeneration.

Dietary cysteine enhances intestinal stemness via CD8+ T cell-derived IL-22

A critical question in physiology is understanding how tissues adapt and alter their cellular composition in response to dietary cues. The mammalian small intestine, a vital digestive organ that absorbs nutrients, is maintained by rapidly renewing Lgr5+ intestinal stem cells (ISCs) at the intestinal crypt base. While Lgr5+ ISCs drive intestinal adaptation by altering self-renewal and differentiation divisions in response to diverse diets such as high-fat diets and fasting regimens, little is known about how micronutrients, particularly amino acids, instruct Lgr5+ ISC fate decisions to control intestinal homeostasis and repair after injury. Here, we demonstrate that cysteine, an essential amino acid, enhances the ability of Lgr5+ ISCs to repair intestinal injury. Mechanistically, the effects of cysteine on ISC-driven repair are mediated by elevated IL-22 from intraepithelial CD8αβ+ T cells. These findings highlight how coupled cysteine metabolism between ISCs and CD8+ T cells augments intestinal stemness, providing a dietary approach that exploits ISC and immune cell crosstalk for ameliorating intestinal damage.

Matrine disturbs the eimeria necatrix-induced loop of tuft cell-intestinal stem cell-goblet cell by inactivating IL-13/JAK2/STAT3 signaling

As sensors in the gut, tuft cells integrate a complex array of luminal signals to regulate the differentiation fate of intestinal stem cells (ISCs), which trigger a loop of tuft cell-ISC-goblet cell after parasitic infection. As a plant-derived alkaloid, Matrine plays a prominent role for standardizing ISC functions in Eimeria necatrix (EN)-exposed chicks. In this study, we investigated the modulation effects of Matrine on the specific intestinal epithelial cell loop in EN-exposed chicks in vivo and intestinal organoids (IOs) ex vivo. The results showed that EN infection resulted in swelling and hemorrhage of the jejunum, accompanied by the increase in levels of sIgA and inflammatory cytokines (IL-6, IL-1β, and TNF-α). And these inflammatory symptoms were effectively relieved by Matrine intervention. Concurrently, Matrine resisted the EN-induced increase in tuft cell numbers and levels of crucial pro-inflammatory factors (IL-25 and IL-13), while also reversing the differentiation of secretory cell progenitors into goblet cells. Importantly, Matrine impeded the upregulation of the inflammatory signaling pathway JAK2/STAT3 in EN-infected chicks and IOs. Conversely, exogenous supplementation of IL-13 or activation of STAT3 via Colivelin eliminated the standardization of the tuft cell-ISC-goblet cell loop by Matrine. Overall, our findings suggested that Matrine intercepted the tuft cell-ISC-goblet cell loop by reinstating IL-13/JAK2/STAT3 signaling after EN infection.

Dietary content and eating behavior in ulcerative colitis: a narrative review and future perspective

Ulcerative colitis (UC) has experienced a steady increase in global incidence and prevalence recently. Current research into UC pathogenesis focuses on the complex interplay of genetic and environmental factors with the immune system and gut microbiome, leading to disruption of the intestinal barrier. Normally, the microbiome, intestinal epithelium, and immune system interact to maintain intestinal homeostasis. However, when this equilibrium is disturbed, a harmful cycle of dysbiosis, immune dysregulation, and inflammation emerges, resulting in intestinal barrier dysfunction and UC progression. Among various risk factors, diet significantly influences epithelial barrier integrity and architectural stability through both direct and indirect mechanisms, shaping the entire UC continuum from pre-clinical prevention to active phase treatment and remission maintenance. This review provides insights into the impact of dietary content and eating behaviors on UC, focusing on specific food, food groups, nutrients, and intermittent fasting, while providing a detailed explanation of why the gut microbiota may mediate the sustained effects of diet across all stages of UC. Additionally, it addresses the limitations of current studies, explores underexamined areas in UC dietary research and proposes potential directions for future research and expansion.

Advancing therapeutic strategies for graft-versus-host disease by targeting gut microbiome dynamics in allogeneic hematopoietic stem cell transplantation: current evidence and future directions

Hematopoietic stem cell transplantation (HSCT) is a highly effective therapy for malignant blood illnesses that pose a high risk, as well as diseases that are at risk due to other variables, such as genetics. However, the prevalence of graft-versus-host disease (GVHD) has impeded its widespread use. Ensuring the stability of microbial varieties and associated metabolites is crucial for supporting metabolic processes, preventing pathogen intrusion, and modulating the immune system. Consequently, it significantly affects the overall well-being and susceptibility of the host to disease. Patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) may experience a disruption in the balance between the immune system and gut bacteria when treated with medicines and foreign cells. This can lead to secondary intestinal inflammation and GVHD. Thus, GM is both a reliable indicator of post-transplant mortality and a means of enhancing GVHD prevention and treatment after allo-HSCT. This can be achieved through various strategies, including nutritional support, probiotics, selective use of antibiotics, and fecal microbiota transplantation (FMT) to target gut microbes. This review examines research advancements and the practical use of intestinal bacteria in GVHD following allo-HSCT. These findings may offer novel insights into the prevention and treatment of GVHD after allo-HSCT.

Innate immune cells link dietary cues to normal and abnormal metabolic regulation

A slew of common metabolic disorders, including type 2 diabetes, metabolic dysfunction-associated steatotic liver disease and steatohepatitis, are exponentially increasing in our sedentary and overfed society. While macronutrients directly impact metabolism and bioenergetics, new evidence implicates immune cells as critical sensors of nutritional cues and important regulators of metabolic homeostasis. A deeper interrogation of the intricate and multipartite interactions between dietary components, immune cells and metabolically active tissues is needed for a better understanding of metabolic regulation and development of new treatments for common metabolic diseases. Responding to macronutrients and micronutrients, immune cells play pivotal roles in interorgan communication between the microbiota, small intestine, metabolically active cells including hepatocytes and adipocytes, and the brain, which controls feeding behavior and energy expenditure. This Review focuses on the response of myeloid cells and innate lymphocytes to dietary cues, their cross-regulatory interactions and roles in normal and aberrant metabolic control.

Prebiotic inulin alleviates anxiety and depression-like behavior in alcohol withdrawal mice by modulating the gut microbiota and 5-HT metabolism

BACKGROUND

Alcohol dependence (AD) is a common psychiatric disorder, often accompanied by anxiety and depression. These comorbidities are linked to disturbances in serotonin (5-HT) metabolism and gut microbiota dysbiosis. Clinical studies suggest that inulin, a prebiotic, can alleviate anxiety and depression in AD patients by affecting the gut microbiota, although the mechanisms remain unclear.

PURPOSE

The purpose of this study is to investigate the potential mechanisms by which inulin, a prebiotic, improves anxiety and depression-like behaviors in AD withdrawal mice. This research is based on the drug and food homology and intestinal treatment of encephalopathy, with the goal of developing new clinical strategies for AD treatment.

STUDY DESIGN

For this purpose, fecal samples from AD patients were analyzed to identify microorganisms associated with AD. An AD withdrawal mouse model was created, with inulin as the intervention and fluvoxamine maleate as the control. Techniques such as 16S microbiome sequencing and UPLC-TQMS-targeted metabolomics were used to assess gut microbiota, short-chain fatty acids (SCFAs) levels, and 5-HT metabolism.

METHODS

The AD withdrawal model was built using the "Drinking-in-the-dark" protocol over 6 weeks. Inulin (2 g/kg/day) and fluvoxamine maleate (30 mg/kg/day) were administered for 4 weeks. The open field test, forced swim test, and tail suspension test were used to evaluate anxiety and depression-like behaviors in mice. ELISA and qRT-PCR assessed 5-HT metabolism in the colon, blood, and prefrontal cortex, while 16S microbiome sequencing analyzed changes in gut microbiota and UPLC-TQMS examined SCFAs levels. Immunohistochemistry was used to study intestinal barrier integrity.

RESULTS

AD patients showed reduced SCFA-producing bacteria such as Faecalibacterium and Roseburia. In mice, AD withdrawal led to anxiety and depression-like behaviors, disrupted 5-HT metabolism, and gut microbiota dysbiosis. Inulin supplementation alleviated these behaviors, increased 5-HT and 5-hydroxytryptophan (5-HTP) levels, upregulated colonic tryptophan hydroxylase 1 (TPH1) expression, and promoted the growth of beneficial bacteria such as Faecalibacterium and Roseburia, while also increasing SCFAs levels.

CONCLUSION

Inulin increases the abundance of Faecalibacterium and Roseburia, enhances SCFAs production, and regulates 5-HT metabolism, improving anxiety and depression-like behaviors in AD withdrawal mice. These findings suggest that inulin may serve as a nutritional intervention for mental health in AD patients by targeting the microbiome-gut-brain axis.

Dietary fiber promotes antigen presentation on intestinal epithelial cells and development of small intestinal CD4+CD8αα+ intraepithelial T cells

The impact of dietary fiber on intestinal T cell development is poorly understood. Here we show that a low fiber diet reduces MHC-II antigen presentation by small intestinal epithelial cells (IECs) and consequently impairs development of CD4+CD8αα+ intraepithelial lymphocytes (DP IELs) through changes to the microbiota. Dietary fiber supports colonization by Segmented Filamentous Bacteria (SFB), which induces the secretion of IFNγ by type 1 innate lymphoid cells (ILC1s) that lead to MHC-II upregulation on IECs. IEC MHC-II expression caused either by SFB colonization or exogenous IFNγ administration induced differentiation of DP IELs. Finally, we show that a low fiber diet promotes overgrowth of Bifidobacterium pseudolongum, and that oral administration of B. pseudolongum reduces SFB abundance in the small intestine. Collectively we highlight the importance of dietary fiber in maintaining the balance among microbiota members that allow IEC MHC-II antigen presentation and define a mechanism of microbiota-ILC-IEC interactions participating in the development of intestinal intraepithelial T cells.

Targeting gut microbiota as a therapeutic target in T2DM: A review of multi-target interactions of probiotics, prebiotics, postbiotics, and synbiotics with the intestinal barrier

The global epidemic of type 2 diabetes mellitus (T2DM) imposes a substantial burden on public health and healthcare expenditures, thereby driving the pursuit of cost-effective preventive and therapeutic strategies. Emerging evidence suggests a potential association between dysbiosis of gut microbiota and its metabolites with T2DM, indicating that targeted interventions aimed at modulating gut microbiota may represent a promising therapeutic approach for the management of T2DM. In this review, we concentrated on the multifaceted interactions between the gut microbiota and the intestinal barrier in the context of T2DM. We systematically summarized that the imbalance of beneficial gut microbiota and its metabolites may constitute a viable therapeutic approach for the management of T2DM. Meanwhile, the mechanisms by which gut microbiota interventions, such as probiotics, prebiotics, postbiotics, and synbiotics, synergistically improve insulin resistance in T2DM are summarized. These mechanisms include the restoration of gut microbiota structure, upregulation of intestinal epithelial cell proliferation and differentiation, enhancement of tight junction protein expression, promotion of mucin secretion by goblet cells, and the immunosuppressive functions of regulatory T cells (Treg) and M2 macrophages. Collectively, these actions contribute to the amelioration of the body's metabolic inflammatory status. Our objective is to furnish evidence that supports the clinical application of probiotics, prebiotics, and postbiotics in the management of T2DM.

Unveiling the therapeutic potential and mechanism of inulin in DSS-induced colitis mice

Inulin has been reported to alleviate colitis. In this study, colitis patients' feces were used to simulate fermentation to demonstrate changes in the microbiota profile in the presence of inulin. We found inulin can reshape the gut microbiota profile of colitis patients, especially by altering the abundance of Faecalibacterium and Blautia. Interestingly, the subsequent co-culture with inulin demonstrated that inulin promoted the growth of these two strains of bacteria. The dextran sodium sulfate (DSS)-induced mouse model was used to examine the effect of inulin and its combination with two probiotics on colitis. Results showed that all three treatments can alleviate the clinical symptoms, including weight-losing, colon-shortening, and the Disease Activity Index (DAI) score. Further investigations showed that the administrations regulate colitis mice's pro- and anti-inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-10, and IL-17. Also, they alter the relative abundance of Faecalibacterium and Blautia, change the short-chain fatty acids (SCFAs) profile in the cecum and colon, and improve the intestinal barrier; specifically, the intervention increased the expressions of Claudin, Occludin, Zonula Occludens (ZO)-1, and Mucin (MUC)-2 in colonic tissues, thus restoring the colonic tissue structure and morphology of colitis mice. Collectively, our results confirm that inulin can alter the colitis patients' characteristic microbial community, and they can ameliorate experimental colitis by inhibiting the TRL4/MyD88/NF-κB signaling pathway-improving the inflammatory response and enhancing the intestinal barrier. In conclusion, we propose that inulin may hold promise as a functional food therapeutic approach for the treatment of colitis.

Goblet cells: guardians of gut immunity and their role in gastrointestinal diseases

Goblet cells (GCs) are specialised guardians lining the intestine. They play a critical role in gut defence and immune regulation. GCs continuously secrete mucus creating a physical barrier to protect from pathogens while harbouring symbiotic gut bacteria adapted to live within the mucus. GCs also form specialised GC-associated passages in a dynamic and regulated manner to deliver luminal antigens to immune cells, promoting gut tolerance and preventing inflammation. The composition of gut bacteria directly influences GC function, highlighting the intricate interplay between these components of a healthy gut. Indeed, imbalances in the gut microbiome can disrupt GC function, contributing to various gastrointestinal diseases like colorectal cancer, inflammatory bowel disease, cystic fibrosis, pathogen infections and liver diseases. This review explores the interplay between GCs and the immune system. We delve into the underlying mechanisms by which GC dysfunction contributes to the development and progression of gastrointestinal diseases. Finally, we examine current and potential treatments that target GCs and represent promising avenues for further investigation.

Nutrigenomic underpinnings of intestinal stem cells in inflammatory bowel disease and colorectal cancer development

Food-gene interaction has been identified as a leading risk factor for inflammatory bowel disease (IBD) and colorectal cancer (CRC). Accordingly, nutrigenomics emerges as a new approach to identify biomarkers and therapeutic targets for these two strongly associated gastrointestinal diseases. Recent studies in stem cell biology have further shown that diet and nutrition signal to intestinal stem cells (ISC) by altering nutrient-sensing transcriptional activities, thereby influencing barrier integrity and susceptibility to inflammation and tumorigenesis. This review recognizes the dietary factors related to both CRC and IBD and investigates their impact on the overlapping transcription factors governing stem cell activities in homeostasis and post-injury responses. Our objective is to provide a framework to study the food-gene regulatory network of disease-contributing cells and inspire new nutrigenomic approaches for detecting and treating diet-related IBD and CRC.

Improved Mass Spectrometry-Based Methods Reveal Abundant Propionylation and Tissue-Specific Histone Propionylation Profiles

Histone posttranslational modifications (PTMs) have crucial roles in a multitude of cellular processes, and their aberrant levels have been linked with numerous diseases, including cancer. Although histone PTM investigations have focused so far on methylations and acetylations, alternative long-chain acylations emerged as new dimension, as they are linked to cellular metabolic states and affect gene expression through mechanisms distinct from those regulated by acetylation. Mass spectrometry is the most powerful, comprehensive, and unbiased method to study histone PTMs. However, typical mass spectrometry-based protocols for histone PTM analysis do not allow the identification of naturally occurring propionylation and butyrylation. Here, we present improved state-of-the-art sample preparation and analysis protocols to quantitate these classes of modifications. After testing different derivatization methods coupled to protease digestion, we profiled common histone PTMs and histone acylations in seven mouse tissues and human normal and tumor breast clinical samples, obtaining a map of propionylations and butyrylations found in different tissue contexts. A quantitative histone PTM analysis also revealed a contribution of histone acylations in discriminating different tissues, also upon perturbation with antibiotics, and breast cancer samples from the normal counterpart. Our results show that profiling only classical modifications is limiting and highlight the importance of using sample preparation methods that allow the analysis of the widest possible spectrum of histone modifications, paving the way for deeper insights into their functional significance in cellular processes and disease states.

The potential of short-chain fatty acid epigenetic regulation in chronic low-grade inflammation and obesity

Obesity and chronic low-grade inflammation, often occurring together, significantly contribute to severe metabolic and inflammatory conditions like type 2 diabetes (T2D), cardiovascular disease (CVD), and cancer. A key player is elevated levels of gut dysbiosis-associated lipopolysaccharide (LPS), which disrupts metabolic and immune signaling leading to metabolic endotoxemia, while short-chain fatty acids (SCFAs) beneficially regulate these processes during homeostasis. SCFAs not only safeguard the gut barrier but also exert metabolic and immunomodulatory effects via G protein-coupled receptor binding and epigenetic regulation. SCFAs are emerging as potential agents to counteract dysbiosis-induced epigenetic changes, specifically targeting metabolic and inflammatory genes through DNA methylation, histone acetylation, microRNAs (miRNAs), and long non-coding RNAs (lncRNAs). To assess whether SCFAs can effectively interrupt the detrimental cascade of obesity and inflammation, this review aims to provide a comprehensive overview of the current evidence for their clinical application. The review emphasizes factors influencing SCFA production, the intricate connections between metabolism, the immune system, and the gut microbiome, and the epigenetic mechanisms regulated by SCFAs that impact metabolism and the immune system.

Enteric glial cells contribute to chronic stress-induced alterations in the intestinal microbiota and barrier in rats

Background

Emerging evidence has demonstrated the impact of psychological stress on intestinal microbiota, however, the precise mechanisms are not fully understood. Enteric glia, a unique type of peripheral glia found within the enteric nervous system (ENS), play an active role in enteric neural circuits and have profound effects on gut functions. In the present study, we tested the hypothesis that enteric glia are involved in the alterations in the intestinal microflora and barrier induced by chronic water-avoidance stress (WAS) in the gut.

Methods and results

Western blotting and immunohistochemical (IHC) staining were used to examine the expression of glial fibrillary acidic protein (GFAP), nitric oxide synthetase (NOS) and choline acety1transferase (ChAT) in colon tissues. 16S rDNA sequencing was performed to analyse the composition of the intestinal microbiota in rats. Changes in the tight junction proteins Occludin, Claudin1 and proliferating cell nuclear antigen (PCNA) in the colon tissues were detected after WAS. The abundance of Firmicutes, Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136 decreased significantly, whereas the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenellaceae-R-7 increased significantly in stressed rats. Meanwhile, the expression of Occludin, Claudin1 and PCNA significantly decreased after WAS. Treatment with L-A-aminohexanedioic acid (L-AA), a gliotoxin that blunts astrocytic function, obviously decreased the abundance of Actinobacteria, Ruminococcaceae_UCG-005 and Christensenel-laceae_R-7 in stressed rats and significantly increased the abundance of Proteobacteria, Lactobacillus and Lachnospiraceae_NK4A136. In addition, the protein expression of colon Occludin, Claudin1, and PCNA increased after intraperitoneal injection of L-AA. Furthermore, the expression level of NOS in colon tissues was significantly decreased, whereas that of ChAT was significantly increased following L-AA treatment.

Conclusions

Our results showed that enteric glial cells may contribute to WAS-induced changes in the intestinal microbiota and barrier function by modulating the activity of NOS and cholinergic neurones in the ENS.

Astaxanthin exerts an adjunctive anti-cancer effect through the modulation of gut microbiota and mucosal immunity

This study aimed to investigate the function of gut microbiota in astaxanthin's adjuvant anticancer effects. Our prior research demonstrated that astaxanthin enhanced the antitumor effects of sorafenib by enhancing the body's antitumor immune response; astaxanthin also regulated the intestinal flora composition of tumor-bearing mice. However, it is presently unknown whether this beneficial effect is dependent on the gut microbiota. We first used broad-spectrum antibiotics to eradicate gut microbiota of tumor-bearing mice, followed by the transplantation of fecal microbiota. The results of this study indicate that the beneficial effects of astaxanthin when combined with molecular targeting are dependent on the presence of intestinal microbiota. Astaxanthin facilitates the infiltration of CD8+ T lymphocytes into the tumor microenvironment and increases Granzyme B production by modulating the intestinal flora. Therefore, it strengthens the body's anti-tumor immune response and synergistically boosts the therapeutic efficacy of drugs. Astaxanthin stimulates the production of cuprocytes and mucus in the intestines by promoting the proliferation of Akkermansia. In addition, astaxanthin enhances the intestinal mucosal immunological function. Our research supports the unique ability of astaxanthin to sustain intestinal flora homeostasis and its function as a dietary immune booster for individuals with tumors.

Effects of Intestinal Microbiota on the Biological Transformation of Arsenic in Zebrafish: Contribution and Mechanism

Both the gut microbiome and their host participate in arsenic (As) biotransformation, while their exact roles and mechanisms in vivo remain unclear and unquantified. In this study, as3mt-/- zebrafish were treated with tetracycline (TET, 100 mg/L) and arsenite (iAsIII) exposure for 30 days and treated with probiotic Lactobacillus rhamnosus GG (LGG, 1 × 108 cfu/g) and iAsIII exposure for 15 days, respectively. Structural equation modeling analysis revealed that the contribution rates of the intestinal microbiome to the total arsenic (tAs) and inorganic As (iAs) metabolism approached 44.0 and 18.4%, respectively. Compared with wild-type, in as3mt-/- zebrafish, microbial richness and structure were more significantly correlated with tAs and iAs, and more differential microbes and microbial metabolic pathways significantly correlated with arsenic metabolites (P < 0.05). LGG supplement influenced the microbial communities, significantly up-regulated the expressions of genes related to As biotransformation (gss and gst) in the liver, down-regulated the expressions of oxidative stress genes (sod1, sod2, and cat) in the intestine, and increased arsenobetaine concentration (P < 0.05). Therefore, gut microbiome promotes As transformation and relieves As accumulation, playing more active roles under iAs stress when the host lacks key arsenic detoxification enzymes. LGG can promote As biotransformation and relieve oxidative stress under As exposure.

Phage lysins for intestinal microbiome modulation: current challenges and enabling techniques

The importance of the microbiota in the intestinal tract for human health has been increasingly recognized. In this perspective, microbiome modulation, a targeted alteration of the microbial composition, has gained interest. Phage lysins, peptidoglycan-degrading enzymes encoded by bacteriophages, are a promising new class of antibiotics currently under clinical development for treating bacterial infections. Due to their high specificity, lysins are considered microbiome-friendly. This review explores the opportunities and challenges of using lysins as microbiome modulators. First, the high specificity of endolysins, which can be further modulated using protein engineering or targeted delivery methods, is discussed. Next, obstacles and possible solutions to assess the microbiome-friendliness of lysins are considered. Finally, lysin delivery to the intestinal tract is discussed, including possible delivery methods such as particle-based and probiotic vehicles. Mapping the hurdles to developing lysins as microbiome modulators and identifying possible ways to overcome these hurdles can help in their development. In this way, the application of these innovative antimicrobial agents can be expanded, thereby taking full advantage of their characteristics.

Immunomodulatory effects of inulin and its intestinal metabolites

"Dietary fiber" (DF) refers to a type of carbohydrate that cannot be digested fully. DF is not an essential nutrient, but it plays an important part in enhancing digestive capacity and maintaining intestinal health. Therefore, DF supplementation in the daily diet is highly recommended. Inulin is a soluble DF, and commonly added to foods. Recently, several studies have found that dietary supplementation of inulin can improve metabolic function and regulate intestinal immunity. Inulin is fermented in the colon by the gut microbiota and a series of metabolites is generated. Among these metabolites, short-chain fatty acids provide energy to intestinal epithelial cells and participate in regulating the differentiation of immune cells. Inulin and its intestinal metabolites contribute to host immunity. This review summarizes the effect of inulin and its metabolites on intestinal immunity, and the underlying mechanisms of inulin in preventing diseases such as type 2 diabetes mellitus, inflammatory bowel disease, chronic kidney disease, and certain cancer types.

Inulin ameliorates metabolic syndrome in high-fat diet-fed mice by regulating gut microbiota and bile acid excretion

Background: Inulin is a natural plant extract that improves metabolic syndrome by modulating the gut microbiota. Changes in the gut microbiota may affect intestinal bile acids. We suggest that inulin may improve metabolism by inducing bile acid excretion by gut microbes. Methods: Male C57/BL mice were fed either a high-fat diet (60% calories) or a regular diet for 16 weeks, with oral inulin (10% w/w). At the end of the experiment, the gene expression levels (FGF15, CD36, Srebp-1c, FASN, and ACC) in the liver and intestines, as well as the serum levels of triglycerides (TGs), low-density lipoprotein (LDL) cholesterol, total cholesterol, and free fatty acids, were collected. The expression of FGF15 was examined using Western blot analysis. The fat distribution in the liver and groin was detected by oil red and hematoxylin and eosin staining. Simultaneously, the levels of serum inflammatory factors (alanine aminotransferase and aspartate aminotransferase) were detected to explore the side effects of inulin. Results: Inulin significantly improved glucose tolerance and insulin sensitivity, and decreased body weight and serum TG and LDL levels, in mice fed normal diet. Furthermore, inulin increased the α-diversity of the gut microbiota and increased the fecal bile acid and TG excretion in inulin-treated mice. In addition, inulin significantly reduced lipid accumulation in liver and inguinal fat, white fat weight, and hepatic steatosis. Western blot analysis showed that inulin reduced the expression of FGF15, a bile acid reabsorption protein. Conclusion: Inulin ameliorates the glucose and lipid metabolic phenotypes of mice fed a normal diet, including decreased intestinal lipid absorption, increased glucose tolerance, increased insulin sensitivity, and decreased body weight. These changes may be caused by an increase in bile acid excretion resulting from changes in the gut microbiota that affect intestinal lipid absorption.