Intraperitoneal supplementation of iron alleviates dextran sodium sulfate-induced colitis by enhancing intestinal barrier function

Butyrate Prevents the Pathogenic Anemia-Inflammation Circuit by Facilitating Macrophage Iron Export

Most patients with inflammatory bowel disease (IBD) develop anemia, which is attributed to the dysregulation of iron metabolism. Reciprocally, impaired iron homeostasis also aggravates inflammation. How this iron-mediated, pathogenic anemia-inflammation crosstalk is regulated in the gut remains elusive. Herein, it is for the first time revealed that anemic IBD patients exhibit impaired production of short-chain fatty acids (SCFAs), particularly butyrate. Butyrate supplementation restores iron metabolism in multiple anemia models. Mechanistically, butyrate upregulates ferroportin (FPN) expression in macrophages by reducing the enrichment of histone deacetylase (HDAC) at the Slc40a1 promoter, thereby facilitating iron export. By preventing iron sequestration, butyrate not only mitigates colitis-induced anemia but also reduces TNF-α production in macrophages. Consistently, macrophage-conditional FPN knockout mice exhibit more severe anemia and inflammation. Finally, it is revealed that macrophage iron overload impairs the therapeutic effectiveness of anti-TNF-α antibodies in colitis, which can be reversed by butyrate supplementation. Hence, this study uncovers the pivotal role of butyrate in preventing the pathogenic circuit between anemia and inflammation.

Effects of Spinach Extract and Licorice Extract on Growth Performance, Antioxidant Capacity, and Gut Microbiota in Weaned Piglets

Anemia and weaning stress are important factors affecting piglet growth performance. Spinach extract and licorice extract have been used to improve anemia and antioxidant capacity, respectively. However, whether they have synergistic effects has not been reported. To evaluate the effects of mixed spinach extract and licorice extract on growth performance, serum biochemistry, antioxidant capacity, and gut microbiota in weaned piglets, a total of 160 weaned piglets were randomly allotted to four treatments with four replications of 10 piglets each. The four treatments were as follows: control (CON) group (basal diet), spinach extract (SE) group (basal diet + 1.5 kg/t spinach extract), licorice extract (LE) group (basal diet + 400 g/t licorice extract), and spinach extract and licorice extract (MIX) group (basal diet + 1.5 kg/t spinach extract + 400 g/t licorice extract). The results showed that, compared with the CON group, diets supplemented with spinach extract and licorice extract significantly increased the average daily gain (p < 0.05), while considerably reducing the feed-to-gain ratio (p < 0.05). Moreover, the MIX group exhibited a significant up-regulation of serum total protein, globulin, albumin, glucose, and triglyceride levels in comparison to the CON group (p < 0.05). Meanwhile, both the anemia and antioxidant capacity of piglets were effectively improved. Notably, the MIX group achieved even better results than the individual supplementation in terms of enhancing growth performance, which could potentially be attributed to the increased abundance of the Rikenellaceae_RC9_gut_group. These results demonstrated that the supplementation of diets with spinach extract and licorice extract improves the absorption of nutrients from the diet and antioxidant capacity in weaned piglets.

Excess iron intake induced liver injury: The role of gut-liver axis and therapeutic potential

Excessive iron intake is detrimental to human health, especially to the liver, which is the main organ for iron storage. Excessive iron intake can lead to liver injury. The gut-liver axis (GLA) refers to the bidirectional relationship between the gut and its microbiota and the liver, which is a combination of signals generated by dietary, genetic and environmental factors. Excessive iron intake disrupts the GLA at multiple interconnected levels, including the gut microbiota, gut barrier function, and the liver's innate immune system. Excessive iron intake induces gut microbiota dysbiosis, destroys gut barriers, promotes liver exposure to gut microbiota and its derived metabolites, and increases the pro-inflammatory environment of the liver. There is increasing evidence that excess iron intake alters the levels of gut microbiota-derived metabolites such as secondary bile acids (BAs), short-chain fatty acids, indoles, and trimethylamine N-oxide, which play an important role in maintaining homeostasis of the GLA. In addition to iron chelators, antioxidants, and anti-inflammatory agents currently used in iron overload therapy, gut barrier intervention may be a potential target for iron overload therapy. In this paper, we review the relationship between excess iron intake and chronic liver diseases, the regulation of iron homeostasis by the GLA, and focus on the effects of excess iron intake on the GLA. It has been suggested that probiotics, fecal microbiota transfer, farnesoid X receptor agonists, and microRNA may be potential therapeutic targets for iron overload-induced liver injury by protecting gut barrier function.

Tuning the Microstructures of Electrospray Multicore Alginate Microspheres for the Enhanced Delivery of Astaxanthin

Multicore alginate microspheres (MCPs) have been demonstrated as promising carriers for bioactive substances. Herein, the influence of the size of the inner core on the bioaccessibility of astaxanthin (AST) was investigated using both in vitro and in vivo methods. MCPs with different inner core sizes were fabricated in which the oil-in-water emulsion with different oil droplet sizes was embedded in alginate microspheres (AST@MCPs) via the electrospray technology. The AST@MCPs appeared as a uniform sphere with an average size of 300 μm. The AST encapsulation efficiency in the AST@MCPs was determined to be more than 68%, which was independent of the inner core size. The bioaccessibility of AST increased from 38.3 to 83.2% as the size of the inner core decreased. Furthermore, the anti-inflammatory activity of AST@MCPs after in vitro simulated digestion was evaluated by LPS-induced RAW264.7 cells. The results suggested that AST@MCPs with a smaller inner core size exhibited a stronger anti-inflammatory activity, which further proved the results obtained from in vitro simulated digestion. As expected, the oral administration of AST@MCPs significantly mitigated colitis symptoms in DSS-induced ulcerative colitis mice. Compared with AST@MCPs with larger inner cores, AST@MCPs with smaller inner cores reflect stronger anti-inflammatory activity in vivo. These results suggested that the bioaccessibility of AST in MCPs increased significantly with the decrease in the inner core size, which may be attributed to the rapid formation of micelles in the intestine. This work provides a simple and efficient strategy to prepare microspheres for the enhanced delivery of AST, which has important implications for the design of health-promoting foods.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Recent advances on emerging nanomaterials for diagnosis and treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic idiopathic inflammatory disorder that affects the entire gastrointestinal tract and is associated with an increased risk of colorectal cancer. Mainstream clinical testing methods are time-consuming, painful for patients, and insufficiently sensitive to detect early symptoms. Currently, there is no definitive cure for IBD, and frequent doses of medications with potentially severe side effects may affect patient response. In recent years, nanomaterials have demonstrated considerable potential for IBD management due to their diverse structures, composition, and physical and chemical properties. In this review, we provide an overview of the advances in nanomaterial-based diagnosis and treatment of IBD in recent five years. Multi-functional bio-nano platforms, including contrast agents, near-infrared (NIR) fluorescent probes, and bioactive substance detection agents have been developed for IBD diagnosis. Based on a series of pathogenic characteristics of IBD, the therapeutic strategies of antioxidant, anti-inflammatory, and intestinal microbiome regulation of IBD based on nanomaterials are systematically introduced. Finally, the future challenges and prospects in this field are presented to facilitate the development of diagnosis and treatment of IBD.

Role of micronutrients in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an autoimmune intestinal disease that includes ulcerative colitis, Crohn's disease, and indeterminate colitis. Patients with IBD are often at risk for malnutrition, including micronutrient deficiencies, due to dietary restrictions and poor intestinal absorption. Micronutrients, including vitamins and minerals, play an important role in the human body's metabolism and maintenance of tissue functions. This article reviews the role of micronutrients in IBD. Micronutrients can affect the occurrence and progression of IBD by regulating immunity, intestinal flora, oxidative stress, intestinal barrier function, and other aspects. Monitoring and timely supplementation of micronutrients are important to delay progression and improve clinical symptoms in IBD patients.

Role of iron in host-microbiota interaction and its effects on intestinal mucosal growth and immune plasticity in a piglet model

Iron is an essential trace element for both the host and resident microbes in the gut. In this study, iron was administered orally and parenterally to anemic piglets to investigate the role of iron in host-microbiota interaction and its effects on intestinal mucosal growth and immune plasticity. We found that oral iron administration easily increased the abundance of Proteobacteria and Escherichia-Shigella, and decreased the abundance of Lactobacillus in the ileum. Furthermore, similar bacterial changes, namely an increase in Proteobacteria, Escherichia-Shigella, and Fusobacterium and a reduction in the Christensenellaceae_R-7_group, were observed in the colon of both iron-supplemented groups. Spearman's correlation analysis indicated that the changed Fusobacterium, Fusobacteria and Proteobacteria in the colon were positively correlated with hemoglobin, colon and spleen iron levels. Nevertheless, it was found that activated mTOR1 signaling, improved villous height and crypt depth in the ileum, enhanced immune communication, and increased protein expression of IL-22 and IL-10 in the colon of both iron-supplemented groups. In conclusion, the benefits of improved host iron outweigh the risks of altered gut microbiota for intestinal mucosal growth and immune regulation in treating iron deficiency anemia.

Iron-rich Candida utilis improves intestinal health in weanling piglets

AIM

This study aimed to investigate the effects of substituting inorganic iron in the diet of weanling piglets with iron-rich Candida utilis on gut morphology, immunity, barrier, and microbiota.

METHODS AND RESULTS

Seventy-two healthy 28-day-old Duroc × Landrace × Yorkshire desexed male weanling piglets were randomly assigned to 2 groups (n = 6), with 6 pens per group and 6 piglets in each pen. The control group was fed a basal diet containing ferrous sulfate (104 mg kg-1 iron), while the experimental group was fed a basal diet supplemented with iron-rich C. utilis (104 mg kg-1 iron). The results show that the growth performance of weanling piglets showed no significantly differences (P > 0.05). Iron-rich C. utilis significantly elevated villus height and decreased crypt depth in the duodenum and jejunum (P < 0.05). Additionally, there was a significant increase in SIgA content, a down-regulated of pro-inflammatory factors expression, and an up-regulated of anti-inflammatory factors expression in the jejunum and ileum of piglets fed iron-rich C. utilis (P < 0.05). The mRNA expression levels of ZO-1, Claudin-1, Occludin, and Mucin2 in the jejunum were significantly increased by iron-rich C. utilis, and were significantly increased ZO-1 and Claudin-1 in the ileum (P < 0.05). The colonic microbiota, however, was not significantly affected by iron-rich C. utilis (P > 0.05).

CONCLUSION

Iron-rich C. utilis improved intestinal morphology and structure, as well as intestinal immunity and intestinal barrier function.

Hydroethanolic Extract of Fritillariae thunbergii Bulbus Alleviates Dextran Sulfate Sodium-Induced Ulcerative Colitis by Enhancing Intestinal Barrier Integrity

The incidence of ulcerative colitis (UC), an inflammatory disorder of the gastrointestinal tract, has rapidly increased in Asian countries over several decades. To overcome the limitations of conventional drug therapies, including biologics for UC management, the development of herbal medicine-derived products has received continuous attention. In this study, we evaluated the beneficial effects of a hydroethanolic extract of Fritillariae thunbergii Bulbus (FTB) in a mouse model of DSS-induced UC. The DSS treatment successfully induced severe colonic inflammation and ulceration. However, the severity of colitis was reduced by the oral administration of FTB. Histopathological examination showed that FTB alleviated the infiltration of inflammatory cells (e.g., neutrophils and macrophages), damage to epithelial and goblet cells in the colonic mucosal layer, and fibrotic lesions. Additionally, FTB markedly reduced the gene expression of proinflammatory cytokines and extracellular matrix remodeling. Immunohistochemical analysis showed that FTB alleviated the decrease in occludin and zonula occludens-1 expression induced by DSS. In a Caco-2 monolayer system, FTB treatment improved intestinal barrier permeability in a dose-dependent manner and increased tight junction expression. Overall, FTB has potential as a therapeutic agent through the improvement of tissue damage and inflammation severity through the modulation of intestinal barrier integrity.

Adjunctive therapeutic effects of micronutrient supplementation in inflammatory bowel disease

Growing evidence suggests that micronutrient status may have some impact on the course of inflammatory bowel disease (IBD). However, micronutrient deficiencies are easily overlooked during the treatment of IBD patients. There have been many studies on micronutrient supplementation, in which several clinical trials have been conducted targeting vitamin D and iron, but the current research is still preliminary for other vitamins and minerals. This review provides an overview of the adjunctive therapeutic effects of micronutrient supplementation in IBD, to summarize the available evidence, draw the attention of clinicians to micronutrient monitoring and supplementation in patients with IBD, and also provide some perspectives for future research directions.

Zeaxanthin Dipalmitate-Enriched Emulsion Stabilized with Whey Protein Isolate-Gum Arabic Maillard Conjugate Improves Gut Microbiota and Inflammation of Colitis Mice

In the present study, protein-polysaccharide Maillard conjugates were used as novel emulsifiers and bioactive carriers. Effects and potential mechanisms of zeaxanthin dipalmitate (ZD)-enriched emulsion stabilized with whey protein isolate (WPI)-gum Arabic (GA) conjugate (WPI-GA-ZD) and ZD-free emulsion (WPI-GA) on gut microbiota and inflammation were investigated using a model of dextran sulfate sodium (DSS)-induced colitis in mice. As a result, supplementation with WPI-GA and WPI-GA-ZD improved the serum physiological and biochemical indicators, decreased the expression of pro-inflammatory cytokines and related mRNA, as well as increased the tight junction proteins to a certain extent. 16S rDNA sequencing analyses showed that supplementation with WPI-GA and WPI-GA-ZD presented differential modulation of gut microbiota and played regulatory roles in different metabolic pathways to promote health. Compared with WPI-GA, the relative abundances of Akkermansia, Lactobacillus and Clostridium_IV genera were enriched by the intervention of WPI-GA-ZD. Overall, the designed carotenoid-enriched emulsion stabilized with protein-polysaccharide conjugates showed potential roles in promoting health.

Aqueous extract of Paeoniae Radix Alba (Paeonia lactiflora Pall.) ameliorates DSS-induced colitis in mice by tunning the intestinal physical barrier, immune responses, and microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is a chronic non-specific intestinal inflammatory disease, the pathogenesis of which is strongly associated with the compromised intestinal barrier. Paeoniae Radix Alba (PRA), the root of Paeonia lactiflora Pall., is a well-known traditional Chinese medicine and an adaptogen used in Hozai, exhibiting appreciable anti-inflammatory and immunomodulatory activity. Nevertheless, the role and mechanism of PRA in UC have yet to be elucidated.

AIM OF THE STUDY

This study was set out to examine the ameliorative effects of the aqueous extract of PRA (i.e., PRA dispensing granule, PRADG) on dextran sulfate sodium (DSS)-induced colitis.

MATERIALS AND METHODS

The chemical components of PRADG was analyzed by HPLC. Colitis model mice were induced by free access to water containing 2.5% DSS for 10 consecutive days, and concurrently, PRADG (0.1025 and 0.41 g/kg) or Salazosulfapyridine (SASP, 450 mg/kg) was given orally from day 1-10. Body weight, disease activity index (DAI), colon length, histologic scoring, and inflammatory response were assessed. Additionally, IL-23/IL-17 axis and tight junction (TJ) proteins, as well as gut microbiota were also investigated under the above-mentioned regimen.

RESULTS

Eight main chemical constituents of CPT were revealed with HPLC analysis. Noticeably, PRADG could effectively lower body weight loss as well as DAI scores, alleviate colon shortening, and reduce the levels of proinflammatory cytokines in mice with colitis. Further exploration found that increment of TJ proteins expression (ZO-1, occludin and claudin-1) and inhibition of IL-23/IL-17 axis-modulated inflammation were observed in PRADG-treated mice. Additionally, the diversity of gut microbiota and the relative abundance of beneficial bacteria were increased following PRADG treatment.

CONCLUSIONS

PRADG could be sufficient to ameliorate colitis by regulating the intestinal physical barrier, immune responses, and gut microbiota in mice. Our findings highlight that PRADG might be a prospective remedy for UC.

Dietary High Dose of Iron Aggravates the Intestinal Injury but Promotes Intestinal Regeneration by Regulating Intestinal Stem Cells Activity in Adult Mice With Dextran Sodium Sulfate-Induced Colitis

The effects of excessive dietary iron intake on the body have been an important topic. The purpose of this study was to investigate the effects of high-dose iron on intestinal damage and regeneration in dextran sodium sulfate (DSS)-induced colitis model mice. A total of 72 8-week-old adult C57BL/6 mice were randomly divided into two dietary treatment groups: the basal diet supplemented with 45 (control) and 450 mg/kg iron (high-iron) from ferrous sulfate. The mice were fed different diets for 2 weeks, and then 2.5% DSS was orally administered to all mice for 7 days. Samples of different tissues were collected on days 0, 3, and 7 post administration (DPA). High-iron treatment significantly decreased the relative weight of the large intestine at 7 DPA but not at 0 DPA or 3 DPA. High dietary iron increased the jejunal villus width at 0 DPA, decreased the villus width and the crypt depth of the jejunum at 3 DPA, and decreased the number of colonic crypts at 7 DPA. Meanwhile, high dietary iron decreased the number of goblet cells in the jejunal villi and the Paneth cells in the jejunal crypts at 0 DPA, increased the number of goblet cells per crypt of the colon at 3 DPA, and the number of Paneth cells in the jejunal crypts, the goblet cells in the colon, the Ki67-positive proliferating cells in the colon, and the Sex-determining region Y-box transcription factor 9⁺ (SOX9) cells in the jejunum crypts and colon at 7 DPA. The organoid formation rate was increased by high-iron treatments at 3 DPA and 7 DPA. High dietary iron treatment decreased the mRNA level of jejunal jagged canonical Notch ligand 2 (Jag-2) at 0 DPA and bone morphogenetic protein 4 (Bmp4) and neural precursor cell-expressed developmentally downregulated 8 (Nedd8) in the jejunum and colon at 7 DPA, whereas it increased the mRNA expression of the serum/glucocorticoid-regulated kinase 1 (Sgk1) in the colon at 3 DPA. The results suggested that a high dose of iron aggravated intestinal injury but promoted intestinal repair by regulating intestinal epithelial cell renewal and intestinal stem cell activity in adult mice with colitis.