Zinc enhances intestinal epithelial barrier function through the PI3K/AKT/mTOR signaling pathway in Caco-2 cells

Demonstration of the effective intestinal immunity activity of a high branched rhamnogalacturonan-I type pectin polysaccharide from wolfberry via exploration its interaction with mechanical barrier

Rhamnogalacturonan-I type pectin polysaccharide from wolfberry has immunity activity, but its intestinal immunity activity and structure-activity relationship in the small intestine was still unclear. This study comparatively investigated the intestinal immune activity of wolfberry-derived high and low branched Rhamnogalacturonan-I type pectin polysaccharides (H-LBP and L-LBP) and explored the interaction mechanism with mechanical barrier. In the normal mechanical barrier model, both H-LBP and L-LBP could cross mechanical barrier with transport rates of 23.2 % and 25 %, thereby directly enhancing macrophage viability and phagocytic ability after crossing the mechanical barrier. The transport mechanism of H-LBP in mechanical barrier included the clathrin- and caveolin-mediated pathways. In the damaged mechanical barrier model, H-LBP could significantly enhance mechanical barrier integrity, reduce the production of neurotransmitter (NO) and inflammatory cytokine (TNF-α), thereby exerting indirectly intestinal immune activity. Transcriptome analysis showed that the interaction mechanism between H-LBP and damaged mechanical barrier mainly involved signaling pathway regulating cell growth and survival (PI3K-AKT). Western blot experiment and molecular docking simulation confirmed that H-LBP could reduce the expression of p-PI3K, p-AKT and cleaved Caspase3. H-LBP had stronger directly and indirectly intestinal immune activity than L-LBP. These findings were useful for the application of H-LBP in improving intestinal immunity oral formulations.

Effects of co-exposure to microplastics and perfluorooctanoic acid on the Caco-2 cells

As plastics are produced and used, humans are inevitably exposed to microplastics (MPs) on a daily basis. The pollution of MPs has aroused widespread human concern. Perfluorooctanoic acid (PFOA), a persistent organic pollutant (POP), can be adsorbed by microplastics and may exacerbate human health hazards. In this study, we investigated the effects of co-exposure of PET MPs and PFOA on the human intestinal tract in terms of both cytotoxicity and intestinal barrier through in vitro experiments. The results showed that PFOA induced cellular oxidative stress, mitochondrial dysfunction exerted cytotoxic effects, and inhibited tight junction (TJ) protein expression causing intestinal barrier damage. PET MPs can synergize with PFOA to exacerbate the deleterious effects on the intestinal tract by decreasing cell membrane permeability to increase PFOA accumulation in the cell and enhancing the ability of PFOA to inhibit zonula occludens-1 (ZO-1) proteins.

A plasma metabolomic analysis revealed the metabolic regulatory mechanism of the water extract of Dendrobium huoshanense in improving streptozotocin-induced type 1 diabetes model rats

D. huoshanense is a traditional Chinese medicine with antidiabetes effects, but the underlying metabolic regulatory mechanism remains unknown. Plasma metabolomic analysis was applied to assess the metabolic regulatory mechanism underlying the alleviation of streptozotocin-induced type 1 diabetes (STZ-T1D) by D. huoshanense. The successfully STZ-T1D model rats were assigned to the model group, the model + water extract of D. huoshanense (DHWE) group, and the model + metformin (MET) group. They were administered the corresponding medication by gavage. After 28 days, the plasma levels of glucose, malondialdehyde (MDA), C-reactive protein (CRP), and total antioxidant capacity (T-AOC) were determined. Morphological changes in the pancreatic islet tissue were analyzed via hematoxylin and eosin (H&E) staining. The expression of occludin-1, zonula occludens protein 1 (ZO-1) and protein kinase RNA-like endoplasmic reticulum kinase (PERK) in the ileum tissue was determined via western blotting. Nontargeted metabolome analysis of the plasma was performed via ultrahigh-performance liquid chromatography. The results revealed that DHWE reduced blood glucose, C-reactive protein, and MDA levels; increased plasma T-AOC; improved intestinal mucous integrity and pancreatic islet morphological structure; and alleviated intestinal endoplasmic reticulum stress. Plasma metabolomics revealed that DHWE significantly increased the levels of ascorbic acid 2-sulfate, L-thyroxine, phosphatidylcholine (PC) (14:0e/5:0), and PC (16:1e/4:0); decreased the levels of D-(-)-fructose and indole-3-lactic acid; and significantly affected ascorbate and aldarate metabolism and glyoxylate and dicarboxylate metabolism in STZ-T1D rats (p < 0.05), and the effects on the citric acid cycle and pyruvate metabolism tended to be significant (p < 0.1). This study confirmed that DHWE alleviated STZ-T1D by reducing oxidative stress and the inflammatory response, enhancing intestinal mucosa integrity and affecting mainly the energy metabolism and vitamin C metabolism of STZ-T1D rats.

Zinc Glycine supplementation improves bone quality in meat geese by modulating gut microbiota, SCFA's, and gut barrier function through Wnt10b/NF-κB axis

Bone disorders are characterized by leg abnormalities and alterations in gut microbiota, which are linked with destruction of bone structure and increased risk of fractures. Zinc (Zn) plays a crucial role in normal bone homeostasis and has been proven to be highly effective against leg problems. The effects of different Zn sources on bone quality were evaluated in this study. A total of 300 one-d-old Wanpu mixed-sexed geese fed 2 basal diets added with best suited levels of 80 mg/kg inorganic zinc (ZnSO4), and 80 mg/kg Organic zinc (Zn-Glycine) for 60 d. Tibia bone mineral density (BMD), ash percentage, and tibia length increased with dietary Zn source (P < 0.05). Micro-computed tomography analysis revealed that Zn-Glycine improved bone mass, potentially due to an increased abundance of Firmicutes and higher SCFA production in the cecum. Dietary Zn Glycine addition reduced intestinal permeability, upregulated the protein expression of tight junction protein (Zonula Occludens-1, Claudin-1), downregulated diamine oxidase (DAO) levels, and increased the abundance of Lactobacillus and Bifidobacterium, which was accompanied by a reduction in inflammatory cytokines levels in the serum, tibia, and cecum. In terms of bone turnover, Zn-Glycine increased alkaline phosphatase (ALP) and other bone markers (Runt-related transcription factor 2- Runx2, Osteoprotegerin- OPG, Osteocalcin- OCN, Suppressor of mother against decapentaplegic- SMAD) expression, resulting in a decrease in osteoclast number and a reduction in serum bone resorption biomarkers, including serum tartrate-resistant acid phosphatase activity and tibia nuclear factor of activated T-cells (NFATC1) and tumor necrosis factor receptor associated factor 6 (TRAF-6) (P < 0.05). Zn-Glycine also enhanced antioxidant capacity by increasing catalase (CAT) and glutathione peroxidase (GSH-PX), resulting in reduced reactive oxygen species (ROS) and malondialdehyde (MDA) production (P<0.05). Zn-Glycine at 80mg/kg in the diet actively reduced (P<0.05) the expression of cell-death-associated proteins (Beclin-1, Caspase-3). Additionally, Zn-Glycine improved intestinal morphology (villus height, villus-to-crypt ratio), supporting efficient nutrient absorption. Immunofluorescence analysis of tibia showed higher expression of wingless type-10b (Wnt-10b) and reduced expression of nuclear factor-kappa B (NF-κB) in Zn-Glycine group compared to ZnSO4 group. These findings underscore the significance of the gut-bone axis and provide new insights into the effect of Zn-Glycine on bone health in meat geese through a key signaling pathway.

Hydroxy-selenomethionine helps cows to overcome heat stress by enhancing antioxidant capacity and alleviating blood-milk barrier damage

Heat stress can lead to decreased feed intake, apoptosis of mammary epithelial cells, and decreased milk yield and quality. Selenium is an important element in the composition of at least 25 selenoproteins. Hydroxy-selenomethionine (HMSeBA) is a novel organic selenium that has been shown to have a better deposition effect. However, whether HMSeBA alleviates damage to the mammary gland blood-milk barrier caused by heat stress and how this affects the performance of dairy cows remain largely unexplored. Therefore, 32 healthy Holstein cows with similar gestation days (150.41 ± 20.07 d), milk yield (36.15 ± 3.02 kg) and parity (3.25 ± 0.51) were selected and randomly divided into two total mixed rations with different selenium (Se) sources: sodium selenite (SSe) and HMSeBA. This study evaluated the outcomes of HMSeBA on antioxidant capacity, immunity, and blood-milk barrier damage in dairy cows during heat stress by collecting the samples of blood, rumen fluid and mammary gland biopsy. The experiment was conducted over 35 d, including a 5-day pre-feeding period and a 30-day experimental period. The temperature and humidity index (THI) were all above 80 throughout the experiment period. The results showed that HMSeBA decreased the respiratory rate (P < 0.001) and the content of inflammatory cytokines in the serum and increased the content of immune factors and antioxidant capacity (P < 0.05). In addition, HMSeBA reduced the expression of inflammatory cytokines and heat shock proteins in mammary gland (P < 0.05). Hematoxylin-eosin-stained pathological sections showed massive thickening of acinar walls and severe destruction of glandular structures in the SSe group, but the structure of the acinar mammary gland in the HMSeBA group was intact. Furthermore, HMSeBA promoted the expression of the phosphatidylinositol 3-kinase (PI3K, P < 0.001)/protein kinase B (AKT, P = 0.011)/mammalian target of rapamycin (mTOR, P = 0.008) pathway and improved the expression of zonula occludens-1 (ZO-1, P = 0.014) and occluding (OCLN, P = 0.012) in the mammary gland, suggesting less damage caused by heat stress to the blood-milk barrier. Our results demonstrated that HMSeBA can improve the antioxidant capacity and immunity of dairy cows and the expression of tight junction proteins in mammary gland to help alleviate the blood-milk barrier damage by heat stress, which could reduce the damage of heat stress on milk yield.

Zinc and Inflammatory Bowel Disease: From Clinical Study to Animal Experiment

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract (GI) with a high incidence rate globally, and IBD patients are often accompanied by zinc deficiency. This review aims to summarize the potential therapeutic value of zinc supplementation in IBD clinical patients and animal models. Zinc supplementation can relieve the severity of IBD especially in patients with zinc deficiency. The clinical severity of IBD were mainly evaluated through some scoring methods involving clinical performance, endoscopic observation, blood biochemistry, and pathologic biopsy. Through conducting animal experiments, it has been found that zinc plays an important role in alleviating clinical symptoms and improving pathological lesions. In both clinical observation and animal experiment of IBD, the therapeutic mechanisms of zinc interventions have been found to be related to immunomodulation, intestinal epithelial repair, and gut microbiota's balance. Furthermore, the antioxidant activity of zinc was clarified in animal experiment. Appropriate zinc supplementation is beneficial for IBD therapy, and the present evidence highlights that alleviating zinc-deficient status can effectively improve the severity of clinical symptoms in IBD patients and animal models.

Dachaihu decoction alleviates septic intestinal epithelial barrier disruption via PI3K/AKT pathway based on transcriptomics and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Dachaihu decoction (DCH) is a famous and ancient TCM formula, extensively utilized for over 1800 years in treating gastrointestinal and inflammatory conditions. Our previous study showed that DCH ameliorated intestinal damage and modulated the gut microflora in septic rats. However, the material basis for these effects and the underlying mechanism of action remains ill-defined. We aimed to explore the pharmaceutical ingredients of DCH and its mechanism in mitigating sepsis-induced intestinal epithelial barrier disruption (IEBD).

MATERIALS AND METHODS

Ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) was used to identify DCH composition. A septic rat model and Caco-2 cells were employed to investigate DCH's effects on IEBD. Transcriptomics and network pharmacology were used to predict potential mechanisms, which were further validated by molecular docking and dynamics simulations. The Modified Murine Sepsis Score (mMSS) and histological assessments were performed. Serum fluorescence intensity of FD4 and the expression of Occludin were evaluated to assess intestinal barrier integrity. And p-PI3K P85, PI3K P85, p-AKT, AKT, Bax and Bcl-2 were determined by Western blot. Cell viability was determined using CCK-8 assay, IL-6 and TNF-α by ELISA and quantitative Real-time PCR (RT-qPCR). The integrity and permeability of single layer of Caco-2 cells were assessed via transepithelial resistance (TEER), alkaline phosphatase (ALP) activity and FD4 permeability.

RESULTS

UHPLC-HRMS identified 180 compounds in DCH. DCH significantly reduced mMSS, improved pathological conditions in the ileum, decreased FD4 serum fluorescence, and enhanced Occludin expression. Transcriptomic and network pharmacology analyses identified the PI3K/AKT pathway as a critical mechanism of action. Molecular docking and dynamics simulations confirmed strong binding of DCH components to PIK3R1. DCH upregulated p-PI3K and p-AKT in ileum tissue of septic rats. DCH improved cell viability, decreased IL-6 and TNF-α, promoted cell survival and Occludin level, and upregulated p-PI3K and p-AKT in LPS-stimulated Caco-2 cells. DCH also maintained TEER, ALP activity and decreased FD4 permeability and these effects were reversed by PI3K inhibitor, LY294002. DCH also downregulated Bax expression and increased Bcl-2 levels in both septic rats and LPS-stimulated Caco-2 cells.

CONCLUSION

DCH ameliorates sepsis-induced IEBD via PI3K/AKT pathway activation, offering a novel therapeutic perspective for sepsis-related intestinal dysfunction.

Gold nanocomposites in colorectal cancer therapy: characterization, selective cytotoxicity, and migration inhibition

The third most prevalent type of cancer in the world, colorectal cancer, poses a significant treatment challenge due to the nonspecific distribution, low efficacy, and high systemic toxicity associated with chemotherapy. To overcome these limitations, a targeted drug delivery system with a high cytotoxicity against cancer cells while maintaining a minimal systemic side effects represents a promising therapeutic approach. Therefore, the aim of this study was to develop an efficient gold nanocarrier for the targeted delivery of the anticancer agent everolimus to Caco-2 cells. A novel gold nanocomposite (EV-β-CD-HA-Chi-AuNCs) functionalized with a targeting ligand (hyaluronic acid), a permeation enhancement excipient (chitosan), and an anticancer inclusive compound consisting of beta-cyclodextrin and everolimus was proposed and prepared via Turkevich method. Characterization was performed with a UV spectrometer, FTIR, Zetasizer, and HRTEM. Its drug release profile was also evaluated in media with three different pH values. Cytotoxicity and biocompatibility studies were performed on a colorectal cancer cell line (Caco-2) and a normal fibroblast line (MRC-5), respectively, via xCELLigence real-time cellular analysis (RTCA) technology. The inhibitory effect on migration was also further tested via the xCELLigence RTCA technique and a scratch assay. Characterization studies revealed the successful formation of EV-β-CD-HA-Chi-AuNCs with a size and charge which are suitable for the use as targeted drug delivery carrier. In the cytotoxic study, the EV-β-CD-HA-Chi-AuNCs showed a lower IC50 (16 ± 1 µg/ml) than the pure drug (25 ± 3 µg/ml) toward a colorectal cell line (Caco-2). In the biocompatibility study, the EV-β-CD-HA-Chi-AuNCs have minimal toxicity, while the pure drug has severe toxicity toward healthy fibroblasts (MRC-5) despite its low concentration. In the cell migration study, the EV-β-CD-HA-Chi-AuNCs also showed a greater inhibitory effect than the pure drug. Compared with the pure drug, the EV-β-CD-HA-Chi-AuNCs exhibit an excellent selective cytotoxicity between cancerous colorectal Caco-2 cells and healthy MRC-5 cells, making it a potential carrier to carry the drug to the cancerous site while maintaining its low toxicity to the surrounding environment. In addition, an increase in the cytotoxic activity of the EV-β-CD-HA-Chi-AuNCs toward cancerous colorectal Caco-2 cells was also observed, which can potentially improve the treatment of colorectal cancer.

Dietary Dihydromyricetin Zinc Chelate Supplementation Improves the Intestinal Health of Magang Geese

To fulfill the nutritional requirements of poultry, effective Zn supplementation is required due to Zn deficiency in basic feed. In this study, we investigated the effects of DMY-Zn (dihydromyricetin zinc chelate) on the growth performance, morphology, and biochemical indices; the expression of intestinal barrier-related genes; the intestinal microflora; and the cecum metabolome of Magang geese. A total of 300 14-day-old Magang geese (equal number of males and females) with an average body weight of 0.82 ± 0.08 kg were randomly divided into five groups and fed a basal diet; these groups were given DMY-Zn (low, medium, or high level of DMY-Zn with 30, 55, or 80 mg/kg Zn added to the basal diet) or ZnSO4 (80 mg/kg Zn added) for 4 weeks. Our results revealed that DMY-Zn significantly impacts growth and biochemical indices and plays a significant role in regulating the intestinal barrier and microflora. DMY-Zn is involved in the upregulation of intestinal barrier gene (ZO1 and MUC2) expression, as well as upregulated Zn-related gene expression (ZIP5). On the other hand, a low concentration of DMY-Zn increased the ɑ diversity index and the abundance of Lactobacillus and Faecalibacterium. Additionally, a cecal metabolomics study showed that the main metabolic pathways affected by DMY-Zn were the pentose phosphate pathway, the biosynthesis of different alkaloids, and the metabolism of sphingolipids. In conclusion, DMY-Zn can reduce feed intake, increase the expression of intestinal barrier-related genes, help maintain the intestinal microflora balance, and increase the abundance of beneficial bacteria in the intestine to improve intestinal immunity.

Xenotransplanted human organoids identify transepithelial zinc transport as a key mediator of intestinal adaptation

Short bowel syndrome (SBS) leads to severe morbidity and mortality. Intestinal adaptation is crucial in improving outcomes. To understand the human gene pathways associated with adaptation, we perform single-cell transcriptomic analysis of human small intestinal organoids explanted from mice with experimental SBS. We show that transmembrane ion pathways, specifically the transepithelial zinc transport pathway genes SLC39A4 and SLC39A5, are upregulated in SBS. This discovery is corroborated by an external dataset, bulk RT-qPCR, and Western blots. Oral zinc supplementation is shown to improve survival and weight gain of SBS mice and increase the proliferation of intestinal crypt cells in vitro. Finally, we identify the upregulation of SLC39A5 and associated transcription factor KLF5 in biopsied intestinal tissue specimens from patients with SBS. Thus, we identify zinc supplementation as a potential therapy for SBS and describe a xenotransplantation model that provides a platform for discovery in other intestinal diseases.

A New Strategy for Dietary Nutrition to Improve Intestinal Homeostasis in Diarrheal Irritable Bowel Syndrome: A Perspective on Intestinal Flora and Intestinal Epithelial Interaction

BACKGROUND AND OBJECTIVES

Although a reasonable diet is essential for promoting human health, precise nutritional regulation presents a challenge for different physiological conditions. Irritable Bowel Syndrome (IBS) is characterized by recurrent abdominal pain and abnormal bowel habits, and diarrheal IBS (IBS-D) is the most common, seriously affecting patients' quality of life. Therefore, the implementation of precise nutritional interventions for IBS-D has become an urgent challenge in the fields of nutrition and food science. IBS-D intestinal homeostatic imbalance involves intestinal flora disorganization and impaired intestinal epithelial barrier function. A familiar interaction is evident between intestinal flora and intestinal epithelial cells (IECs), which together maintain intestinal homeostasis and health. Dietary patterns, such as the Mediterranean diet, have been shown to regulate gut flora, which in turn improves the body's health by influencing the immune system, the hormonal system, and other metabolic pathways.

METHODS

This review summarized the relationship between intestinal flora, IECs, and IBS-D. It analyzed the mechanism behind IBS-D intestinal homeostatic imbalance by examining the interactions between intestinal flora and IECs, and proposed a precise dietary nutrient intervention strategy.

RESULTS AND CONCLUSION

This increases the understanding of the IBS-D-targeted regulation pathways and provides guidance for designing related nutritional intervention strategies.

Effect of Organic, Nano, and Inorganic Zinc Sources on Growth Performance, Antioxidant Function, and Intestinal Health of Young Broilers

The study aimed to determine the effects of different zinc sources on growth performance, antioxidant function, and intestinal health of broilers. In total, 240 Ross 308 male broilers with similar weight were randomly assigned to 4 treatments, including zinc sulfate, methionine zinc (Zn-Met), glycine zinc (Zn-Gly), and nano-zinc oxide (ZnO-NPs), with 80 mg zinc/kg diet supplementation. The experiment lasted for 21 days. Results showed dietary supplemental Zn-Gly and Zn-Met increased average daily gain during 1-14 days (P = 0.011), and Zn-Gly, Zn-Met, and ZnO-NP supplementation decreased the ratio of feed to gain during 1-21 days (P = 0.003) compared to zinc sulfate. ZnO-NPs supplementation tended to increase total SOD activity (P = 0.068) and had higher serum IgA content and lower MDA level than the other three groups (P < 0.05). Compared with zinc sulfate, Zn-Met and ZnO-NP supplementation decreased TNF-α mRNA expression (P = 0.048). However, serum biochemical indices, intestinal morphology, and mRNA expressions of tight junction proteins were not affected by different zinc sources (P > 0.05). A differential trend was observed in the beta diversity of bacterial communities among four groups (P = 0.082). The LEfSe analysis showed that bacterial genera Blautia, Ruminococcaceae, Clostridia, Anaerostipes, Eubacterium_ventriosum, Merdibacter, and Oscillospira were enriched in the ZnSO4 group, and the genera Eubacterium_hallii and Anaerotruncus were enriched in the Zn-Gly group. The genera UCG-009 and UCG010 were enriched in ZnO-NPs and Zn-Met groups, respectively. It should be stated dietary supplemental Zn-Met improved growth performance, ZnO-NPs promoted IgA production and reduced occurrences of oxidative stress and inflammation, and different zinc sources enriched different jejunal bacteria genera.

Comprehensive review of milk fat globule membrane proteins across mammals and lactation periods in health and disease

Milk fat globule membrane (MFGM) is a three-layer membrane-like structure encasing natural milk fat globules (MFGs). MFGM holds promise as a nutritional supplement because of the numerous physiological functions of its constituent protein. This review summarizes and compares the differences in MFGM protein composition across various species, including bovines, goats, camels, mares, and donkeys, and different lactation periods, such as colostrum and mature milk, as assessed by techniques such as proteomics and mass spectrometry. We also discuss the health benefits of MFGM proteins throughout life. MFGM proteins promote intestinal development, neurodevelopment, and glucose and lipid metabolism by upregulating tight junction protein expression, brain function-related genes, and glucose and fatty acid biosynthesis processes. We focus on the mechanisms underlying these beneficial effects of MFGM proteins. MFGM proteins activate key substances in in signaling pathways, such as the phosphatidylinositol 3-kinase/protein kinase B, mitogen-activated protein kinase, and myosin light chain kinase signaling pathways. Overall, the consumption of MFGM proteins plays an essential role in conferring health benefits, some of which are important throughout the mammalian life cycle.

Two Doses of Zn Induced Different Microbiota Profiles and Dietary Zinc Supplementation Affects the Intestinal Microbial Profile, Intestinal Microarchitecture and Immune Response in Pigeons

We aimed to explore the effects of two different doses of Zn on the fecal microbiota in pigeons and the correlation between these effects and intestinal immune status. Zn doses affected pigeon growth performance, and pigeons in the T60 (60 mg/kg Zn) and T90 (90 mg/kg Zn) groups exhibited higher villus height and crypt depth in duodenum and ileum compared to the control group, respectively. Supplementation with Zn increased the expression of the IL8, CD798, TJP and NKTR genes (p < 0.05), while enhancing serum immunoglobulin (Ig) G, IgM, and IgA concentrations compared to the control pigeons (p < 0.05). T60 treatment reduced relative Actinobacteriota abundance, while Lactobacillus spp. abundance was highest in the T90 group compared to the two other groups. The core functional genera significantly associated with immune indices in these pigeons were Rhodococcus erythropolis and Lactobacillus ponti. Our findings will help facilitate the application of dietary Zn intake in pig production.

Potential of nutraceuticals in celiac disease

Celiac Disease (CD) is the most common hereditarily-based food intolerance worldwide and a chronic inflammatory condition. The current standard treatment for CD involves strict observance and compliance with a gluten-free diet (GFD). However, maintaining a complete GFD poses challenges, necessitating the exploration of alternative therapeutic approaches. Nutraceuticals, bioactive products bridging nutrition and pharmaceuticals, have emerged as potential candidates to regulate pathways associated with CD and offer therapeutic benefits. Despite extensive research on nutraceuticals in various diseases, their role in CD has been relatively overlooked. This review proposes comprehensively assessing the potential of different nutraceuticals, including phytochemicals, fatty acids, vitamins, minerals, plant-based enzymes, and dietary amino acids, in managing CD. Nutraceuticals exhibit the ability to modulate crucial CD pathways, such as regulating gluten fragment accessibility and digestion, intestinal barrier function, downregulation of tissue transglutaminase (TG2), intestinal epithelial morphology, regulating innate and adaptive immune responses, inflammation, oxidative stress, and gut microbiota composition. However, further investigation is necessary to fully elucidate the underlying cellular and molecular mechanisms behind the therapeutic and prophylactic effects of nutraceuticals for CD. Emphasizing such research would contribute to future developments in CD therapies and interventions.

Combination of Hydrolysable Tannins and Zinc Oxide on Enterocyte Functionality: In Vitro Insights

The management of gastrointestinal disease in animals represents a significant challenge in veterinary and zootechnic practice. Traditionally, acute symptoms have been treated with antibiotics and high doses of zinc oxide (ZnO). However, concerns have been raised regarding the potential for microbial resistance and ecological detriment due to the excessive application of this compound. These concerns highlight the urgency of minimizing the use of ZnO and exploring sustainable nutritional solutions. Hydrolysable tannins (HTs), which are known for their role in traditional medicine for acute gastrointestinal issues, have emerged as a promising alternative. This study examined the combined effect of food-grade HTs and subtherapeutic ZnO concentration on relevant biological functions of Caco-2 cells, a widely used model of the intestinal epithelial barrier. We found that, when used together, ZnO and HTs (ZnO/HTs) enhanced tissue repair and improved epithelial barrier function, normalizing the expression and functional organization of tight junction proteins. Finally, the ZnO/HTs combination strengthened enterocytes' defense against oxidative stress induced by inflammation stimuli. In conclusion, combining ZnO and HTs may offer a suitable and practical approach for decreasing ZnO levels in veterinary nutritional applications.

Effects of Dietary Valine Chelated Zinc Supplementation on Growth Performance, Antioxidant Capacity, Immunity, and Intestine Health in Weaned Piglets

This study was conducted to investigate the effects of dietary valine chelated zinc (ZnVal) supplementation on growth performance, antioxidant capacity, immunity, and intestine health in weaned piglets. A total of 240 healthy 35-day-old weaned piglets (Duroc × Landrace × Yorkshire, average weight 10.70 ± 0.14 kg) were randomly divided into five groups with six replicate pens and eight piglets per pen. Dietary treatments were a corn-soybean meal basal diet supplemented with 0, 25, 50, 75, and 100 mg/kg ZnVal, respectively. The experiment lasted for 28 days. Results showed that average daily gain (ADG) was increased (P < 0.05) by ZnVal with 75-100 mg/kg supplementation on days 15-28 and with 50-100 mg/kg supplementation on days 1-28. Supplementation of 25-100 mg/kg ZnVal reduced (P < 0.01) the diarrhea rate of weaned piglets on days 1 to 14 and 1 to 28. Dietary supplementation with 25-100 mg/kg ZnVal increased (P < 0.05) copper/zinc-superoxide dismutase (Cu/Zn-SOD) and decreased malonaldehyde (MDA) activities in the serum on day 14 and 28. Supplementation of 25-100 mg/kg ZnVal increased (P < 0.05) glutathione peroxidase (GSH-Px) activity in serum on day 14. Additionally, the supplementation of 75 mg/kg ZnVal significantly increased the activity of superoxide dismutase (SOD) and Cu/Zn-SOD in the liver (P < 0.05). Furthermore, the supplementation of 25-100 mg/kg ZnVal significantly increased the total antioxidant capacity (T-AOC) in the liver (P < 0.05). Higher (P < 0.05) concentrations of IgG in the serum were measured from piglets supplemented with 75-100 mg/kg ZnVal on day 14 and dietary supplementation with 25-100 mg/kg ZnVal increased the level of immunoglobulin G (IgG) in serum on day 28 (P < 0.05). In addition, higher (P < 0.05) concentrations of immunoglobulin A (IgA) in the duodenum and ileum were measured from piglets supplemented with 75 mg/kg ZnVal and the supplementation of 25-100 mg/kg ZnVal also showed a higher (P < 0.05) concentration of immunoglobulin G (IgG) in duodenum. Supplementation of 50-100 mg/kg ZnVal increased the villus height and villus height/crypt depth of jejunum (P < 0.05). Moreover, dietary supplementation with 75-100 mg/kg ZnVal showed a higher (P < 0.05) concentration of zinc in the liver and supplementation of 50-100 mg/kg ZnVal increased (P < 0.05) the concentration of zinc in the heart, spleen, and kidney. In conclusion, the present research showed that supplementation of ZnVal improves growth performance by increasing antioxidant capacity and immunity and regulating intestinal morphology and the optimal inclusion level of ZnVal was 65~80 mg/kg.

Zinc alleviates thermal stress-induced damage to the integrity and barrier function of cultured chicken embryonic primary jejunal epithelial cells via the MAPK and PI3K/AKT/mTOR signaling pathways

Zinc (Zn) could alleviate the adverse effect of high temperature (HT) on intestinal integrity and barrier function of broilers, but the underlying mechanisms remain unclear. We aimed to investigate the possible protective mechanisms of Zn on primary cultured broiler jejunal epithelial cells exposed to thermal stress (TS). In Exp.1, jejunal epithelial cells were exposed to 40℃ (normal temperature, NT) and 44℃ (HT) for 1, 2, 4, 6, or 8 h. Cells incubated for 8 h had the lowest transepithelial resistance (TEER) and the highest phenol red permeability under HT. In Exp.2, the cells were preincubated with different Zn sources (Zn sulfate as iZn and Zn proteinate with the moderate chelation strength as oZn) and Zn supplemental levels (50 and 100 µmol/L) under NT for 24 h, and then continuously incubated under HT for another 8 h. TS increased phenol red permeability, lactate dehydrogenase (LDH) activity and p-PKC/PKC level, and decreased TEER, cell proliferation, mRNA levels of claudin-1, occludin, zona occludens-1 (ZO-1), PI3K, AKT and mTOR, protein levels of claudin-1, ZO-1 and junctional adhesion molecule-A (JAM-A), and the levels of p-ERK/ERK, p-PI3K/PI3K and p-AKT/AKT. Under HT, oZn was more effective than iZn in increasing TEER, occludin, ZO-1, PI3K, and AKT mRNA levels, ZO-1 protein level, and p-AKT/AKT level; supplementation with 50 μmol Zn/L was more effective than 100 μmol Zn/L in increasing cell proliferation, JAM-A, PI3K, AKT, and PKC mRNA levels, JAM-A protein level, and the levels of p-ERK/ERK and p-PI3K/PI3K; furthermore, supplementation with 50 μmol Zn/L as oZn had the lowest LDH activity, and the highest ERK, JNK-1, and mTOR mRNA levels. Therefore, supplemental Zn, especially 50 μmol Zn/L as oZn, could alleviate the TS-induced integrity and barrier function damage of broiler jejunal epithelial cells possibly by promoting cell proliferation and tight junction protein expression via the MAPK and PI3K/AKT/mTOR signaling pathways.

Beneficial effect of heat-killed Lactiplantibacillus plantarum L-137 on intestinal barrier function of rat small intestinal epithelial cells

Heat-killed Lactiplantibacillus plantarum L-137 (HK L-137) has been suggested to enhance the intestinal barrier in obese mice, leading to improvement of metabolic abnormalities and adipose tissue inflammation, and in healthy humans with overweight, leading to improvement of systemic inflammation. However, its detailed mechanism of action has not been clarified. Therefore, this study investigated the effects of HK L-137 on the permeability of rat small intestinal epithelial IEC-6 cells, tight junction-related gene and protein expression and localization, and intracellular signaling pathways involved in barrier function. Treatment of IEC-6 cells with HK L-137 for 26 h significantly reduced the permeability to fluorescein isothiocyanate-dextran (FD-4). HK L-137 also increased gene and protein expression of zonula occludens-1 (ZO-1), an important tight junction protein, without affecting the localization. Furthermore, inhibition of the extracellular signal-regulated kinase (ERK)1/2 pathway in IEC-6 cells canceled the HK L-137-related reduction in permeability to FD-4. Phosphorylation of ERK in IEC-6 cells was induced 15 min after the addition of HK L-137. These results suggest that HK L-137 reduces intestinal permeability partly through activating the ERK pathway and increasing expression of the ZO-1 gene and protein. Enhancement of intestinal barrier function with HK L-137 might be effective in preventing and treating leaky gut, for which no specific therapeutic tool has been established.

Betaine addition to the diet alleviates intestinal injury in growing rabbits during the summer heat through the AAT/mTOR pathway

BACKGROUND

The aim of this experiment was to investigate the effect of different levels of betaine (Bet) inclusion in the diet on the intestinal health of growing rabbits under summer heat. A total of 100 weaned Qixing meat rabbits aged 35 d with body weight of 748.61 ± 38.59 g were randomly divided into 5 treatment groups: control group (basal diet) and Bet groups (basal diet + 0.75, 1.0, 1.5 or 2.0 g/kg Bet). The average daily temperature in the rabbitry during the experiment was 30.48 °C and the relative humidity was 69.44%.

RESULTS

Dietary addition of Bet had no significant effect on growth performance and health status of growing rabbits (P > 0.05), but it increased ileal secretory immunoglobulin A content compared to the control under summer heat (P < 0.05). Addition of 0.75 g/kg Bet up-regulated jejunal IL-4, down-regulated ileal TNF-α expression (P < 0.05). The addition of 1.0 g/kg Bet increased the villi height (VH) in the jejunum (P < 0.05). Serum glucose levels were reduced, and the expression of SLC6A20 was up-regulated in jejunum and ileum of rabbits fed with 1.5 g/kg Bet (P < 0.05). When added at 2.0 g/kg, Bet reduced serum HSP70 content, increased jejunal VH, and up-regulated duodenal SLC7A6, SLC38A2, mTOR and 4EBP-2 expression (P < 0.05). Correlation analysis revealed that intestinal mTOR expression was significantly and positively correlated with SLC7A6, SLC38A2, SLC36A1 and IL-4 expression (P < 0.05).

CONCLUSIONS

Dietary addition of Bet can up-regulate the expression of anti-inflammatory factors through the AAT/mTOR pathway, improve the intestinal immune function, alleviate intestinal damage in growing rabbits caused by summer heat, and improve intestinal health.

miR-138-5p ameliorates intestinal barrier disruption caused by acute superior mesenteric vein thrombosis injury by inhibiting the NLRP3/HMGB1 axis

Background

Acute superior mesenteric venous thrombosis (ASMVT) decreases junction-associated protein expression and intestinal epithelial cell numbers, leading to intestinal epithelial barrier disruption. Pyroptosis has also recently been found to be one of the important causes of mucosal barrier defects. However, the role and mechanism of pyroptosis in ASMVT are not fully understood.

Methods

Differentially expressed microRNAs (miRNAs) in the intestinal tissues of ASMVT mice were detected by transcriptome sequencing (RNA-Seq). Gene expression levels were determined by RNA extraction and reverse transcription-quantitative PCR (RT-qPCR). Western blot and immunofluorescence staining analysis were used to analyze protein expression. H&E staining was used to observe the intestinal tissue structure. Cell Counting Kit-8 (CCK-8) and fluorescein isothiocyanate/propidine iodide (FITC/PI) were used to detect cell viability and apoptosis, respectively. Dual-luciferase reporter assays prove that miR-138-5p targets NLRP3.

Results

miR-138-5p expression was downregulated in ASMVT-induced intestinal tissues. Inhibition of miR-138-5p promoted NLRP3-related pyroptosis and destroyed tight junctions between IEC-6 cells, ameliorating ASMVT injury. miR-138-5p targeted to downregulate NLRP3. Knockdown of NLRP3 reversed the inhibition of proliferation, apoptosis, and pyroptosis and the decrease in tight junction proteins caused by suppression of miR-138-5p; however, this effect was later inhibited by overexpressing HMGB1. miR-138-5p inhibited pyroptosis, promoted intestinal epithelial tight junctions and alleviated ASMVT injury-induced intestinal barrier disruption via the NLRP3/HMGB1 axis.

Zinc proteinate with moderate chelation strength enhances zinc absorption by upregulating the expression of zinc and amino acid transporters in primary cultured duodenal epithelial cells of broiler embryos

Recent study showed that zinc (Zn) and amino acid transporters may be involved in enhancing Zn absorption from Zn proteinate with moderate chelation strength (Zn-Prot M) in the duodenum of broilers. However, the specific mechanisms by which Zn-Prot M promotes the above Zn absorption are unknown. Therefore, in this study, 3 experiments were conducted to investigate specific and direct effects of Zn-Prot M and Zn sulfate (ZnS) on Zn absorption and expression of related transporters in primary duodenal epithelial cells of broiler embryos so as to preliminarily address possible mechanisms. In experiment 1, cells were treated with 100 μmol Zn/L as ZnS or Zn-Prot M for 20, 40, 60, 80, 100, or 120 min. Experiment 2 consisted of 3 sub-experiments. In experiment 2A, cells were treated with a Zn-unsupplemented basal medium (Control) or the basal medium supplemented with 100 or 200 μmol Zn/L as ZnS or Zn-Prot M for 60 min; in experiment 2B, cells were treated with a Zn-unsupplemented basal medium (Control) or the basal medium supplemented with 200 μmol Zn/L of as the ZnS or Zn-Prot M for 120 min; in experiment 2C, cells were treated with a Zn-unsupplemented basal medium (Control) or the basal medium supplemented with 400 or 800 μmol Zn/L as ZnS or Zn-Prot M for 120 min. In experiment 3, cells were treated with a Zn-unsupplemented basal medium (Control) or the basal medium supplemented with 400 μmol Zn/L as ZnS or Zn-Prot M for 120 min. The results of experiment 1 indicated that the minimum incubation time for saturable Zn absorption was determined to be 50.83 min using the best fit line. The results in experiment 2 demonstrated that a Zn concentration of 400 μmol/L and an incubation time of 120 min were suitable to increase the absorption of Zn from Zn-Prot M compared to ZnS. In experiment 3, Zn absorption across cell monolayers was significantly increased by Zn addition (P < 0.05), and was significantly greater with Zn-Prot M than with ZnS (P < 0.05). Compared to the control, Zn addition significantly decreased Zn transporter 10 and peptide-transporter 1 mRNA expression levels and increased y + L-type amino transporter 2 (y + LAT2) protein abundance (P < 0.05). Moreover, protein expression levels of zrt/irt-like protein 3 (ZIP3), zrt-irt-like protein 5 (ZIP5), and y + LAT2 were significantly greater for Zn-Prot M than for ZnS (P < 0.05). These findings suggest that Zn-Prot M promote Zn absorption by increasing ZIP3, ZIP5 and y + LAT2 protein expression levels in primary duodenal epithelial cells.

Urolithin A conjugation with NSAIDs inhibits its glucuronidation and maintains improvement of Caco-2 monolayers' barrier function

Urolithin A (UA) is an ellagitannin-derived postbiotic metabolite which emerged as a promising health-boosting agent, promoting mitophagy, improving skeletal muscle function, and suppressing the inflammatory response. However, phase II intestinal metabolism severely limits its biopotency, leading to the formation of nonactive glucuronides. To address this constraint, a set of new UA derivatives (UADs), conjugated with nonsteroidal anti-inflammatory drugs (NSAIDs), was synthesized. The bioavailability and inhibitory activity of UADs against UA-glucuronidation were evaluated using differentiated Caco-2 cell monolayers. Parallelly, after the administration of tested substances, the transepithelial electrical resistance (TEER) of the cell monolayers was continuously monitored using the CellZscope device. Though investigated UADs did not penetrate Caco-2 monolayers, all of them significantly suppressed the glucuronidation rate of UA, while conjugates with diclofenac increased the concentration of free molecule on the basolateral side. Moreover, esters of UA with diclofenac (DicloUA) and aspirin (AspUA) positively influenced cell membrane integrity. Western blot analysis revealed that some UADs, including DicloUA, increased the expression of pore-sealing tight junction proteins and decreased the level of pore-forming claudin-2, which may contribute to their beneficial activity towards the barrier function. To provide comprehensive insight into the mechanism of action of DicloUA, Caco-2 cells were subjected to transcriptomic analysis. Next-generation sequencing (NGS) uncovered substantial changes in the expression of genes involved, for instance, in multivesicular body organization and zinc ion homeostasis. The results presented in this study offer new perspectives on the beneficial effects of modifying UA's structure on its intestinal metabolism and bioactivity in vitro.

Luteolin/ZnO nanoparticles attenuate neuroinflammation associated with diabetes via regulating MicroRNA-124 by targeting C/EBPA

OBJECTIVE

The most prevalent brain-specific microRNA, MicroRNA-124, exhibits anti-inflammatory properties. Luteolin nano-formulation with Zn oxide in the form of L/ZnO NPs may boost anti-diabetic properties; however, its beneficial effect on miRNAs is yet unknown in diabetes. The effectiveness of L/ZnONPs supplements in preventing diabetic neurodegeneration by modulating inflammatory responses in a diabetic model was investigated.

METHODS

A diabetic rat model was induced by a high-fat diet and streptozotocin (30 mg/kg I.P.). Plasma glucose, insulin, and HOMR-IR levels, as well as cytokines, lipid peroxidation, GSH/GSSG, and glucose transporter 1, were determined along with the tight junction proteins occludin (OCLN) and zona occludens 1 (ZO-1). Moreover, the expressions of brain CCAAT/enhancer-binding protein (C/EBPA mRNA), miR-124, glial fibrillary acidic protein (GFAP), and NF-kBp65 were measured alongside the histological investigation.

RESULTS

The results revealed that L/ZnO NPs were able to diminish lipid peroxidation, increase the activity of antioxidant enzymes, and reduce inflammation under oxidative stress. Consequently, it was able to reduce hyperglycemia, elevate insulin levels, and improve insulin resistance. Besides, L/ZnO NPs upregulate miR-124, reduce C/EBPA mRNA, increase BCl-2, and inhibit apoptosis. The results indicate that diabetes raises BBB permeability via tight junction protein decline, which is restored following L/ZnO NPs treatment. Luteolin/ZnO NPs regulate miR-124 and microglia polarization by targeting C/EBPA and are expected to alleviate inflammatory injury via modulation of the redox-sensitive signal transduction pathways. Luteolin/ZnO NPs have a novel target for the protection of the BBB and the prevention of neurological complications in diabetes.

The mechanism of traditional medicine in alleviating ulcerative colitis: regulating intestinal barrier function

Ulcerative colitis (UC) is an idiopathic inflammatory disease mainly affects the large bowel and the rectum. The pathogenesis of this disease has not been fully elucidated, while the disruption of the intestinal barrier function triggered by various stimulating factors related to the host genetics, immunity, gut microbiota, and environment has been considered to be major mechanisms that affect the development of UC. Given the limited effective therapies, the treatment of this disease is not ideal and its incidence and prevalence are increasing. Therefore, developing new therapies with high efficiency and efficacy is important for treating UC. Many recent studies disclosed that numerous herbal decoctions and natural compounds derived from traditional herbal medicine showed promising therapeutic activities in animal models of colitis and have gained increasing attention from scientists in the study of UC. Some of these decoctions and compounds can effectively alleviate colonic inflammation and relieve clinical symptoms in animal models of colitis via regulating intestinal barrier function. While no study is available to review the underlying mechanisms of these potential therapies in regulating the integrity and function of the intestinal barrier. This review aims to summarize the effects of various herbal decoctions or bioactive compounds on the severity of colonic inflammation via various mechanisms, mainly including regulating the production of tight junction proteins, mucins, the composition of gut microbiota and microbial-associated metabolites, the infiltration of inflammatory cells and mediators, and the oxidative stress in the gut. On this basis, we discussed the related regulators and the affected signaling pathways of the mentioned traditional medicine in modulating the disruption or restoration of the intestinal barrier, such as NF-κB/MAPK, PI3K, and HIF-1α signaling pathways. In addition, the possible limitations of current studies and a prospect for future investigation and development of new UC therapies are provided based on our knowledge and current understanding. This review may improve our understanding of the current progression in studies of traditional medicine-derived therapies in protecting the intestinal barrier function and their roles in alleviating animal models of UC. It may be beneficial to the work of researchers in both basic and translational studies of UC.

Consumption of honey ameliorates lipopolysaccharide-induced intestinal barrier dysfunction via upregulation of tight junction proteins

PURPOSE

The leaky gut barrier is an important factor leading to various inflammatory gastrointestinal disorders. The nutritional value of honey and variety of its health benefits have long been recognized. This study was undertaken to assess the role of Indian mustard honey in preventing lipopolysaccharide (LPS)-induced intestinal barrier dysfunction using a combination of in vitro and in vivo experimental model systems.

METHODS

LPS was used to induce intestinal barrier damage in a trans-well model of Caco-2 cells (1 µg/ml) and in Swiss albino mice (5 mg/kg body weight). Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) were used to analyse sugar and phenolic components in honey samples. The Caco-2 cell monolayer integrity was evaluated by transepithelial electrical resistance (TEER) and paracellular permeability assays. The histopathology of intestinal tissue was analysed by haematoxylin and eosin dual staining. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to quantify the transcription of genes. The protein expression was analysed by immunofluorescence, western blot and ELISA-based techniques.

RESULTS

The in vitro data showed that honey prevented LPS-induced intestinal barrier dysfunction dose dependently as was measured by TEER and paracellular flux of FITC-dextran dye. Further, the in vivo data showed a prophylactic effect of orally administered honey as it prevented the loss of intestinal barrier integrity and villus structure. The cellular localization and expression of tight junction (TJ) proteins were upregulated along with downregulation of pro-inflammatory cytokines in response to the administration of honey with LPS.

CONCLUSIONS

The findings of this study suggest a propitious role of honey in the maintenance of TJ protein integrity, thereby preventing LPS-induced intestinal barrier disintegration.

Specific Milk Composition of miR-30b Transgenic Mice Associated with Early Duodenum Maturation in Offspring with Lasting Consequences for Growth

BACKGROUND

Milk composition is complex and includes numerous components essential for offspring growth and development. In addition to the high abundance of miR-30b microRNA, milk produced by the transgenic mouse model of miR-30b-mammary deregulation displays a significantly altered fatty acid profile. Moreover, wild-type adopted pups fed miR-30b milk present an early growth defect.

OBJECTIVE

This study aimed to investigate the consequences of miR-30b milk feeding on the duodenal development of wild-type neonates, a prime target of suckled milk, along with comprehensive milk phenotyping.

METHODS

The duodenums of wild-type pups fed miR-30b milk were extensively characterized at postnatal day (PND)-5, PND-6, and PND-15 using histological, transcriptomic, proteomic, and duodenal permeability analyses and compared with those of pups fed wild-type milk. Milk of miR-30b foster dams collected at mid-lactation was extensively analyzed using proteomic, metabolomic, and lipidomic approaches and hormonal immunoassays.

RESULTS

At PND-5, wild-type pups fed miR-30b milk showed maturation of their duodenum with 1.5-fold (P < 0.05) and 1.3-fold (P < 0.10) increased expression of Claudin-3 and Claudin-4, respectively, and changes in 8 duodenal proteins (P < 0.10), with an earlier reduction in paracellular and transcellular permeability (183 ng/mL fluorescein sulfonic acid [FSA] and 12 ng/mL horseradish peroxidase [HRP], respectively, compared with 5700 ng/mL FSA and 90 ng/mL HRP in wild-type; P < 0.001). Compared with wild-type milk, miR-30b milk displayed an increase in total lipid (219 g/L compared with 151 g/L; P < 0.05), ceramide (17.6 μM compared with 6.9 μM; P < 0.05), and sphingomyelin concentrations (163.7 μM compared with 76.3 μM; P < 0.05); overexpression of 9 proteins involved in the gut barrier (P < 0.1); and higher insulin and leptin concentrations (1.88 ng/mL and 2.04 ng/mL, respectively, compared with 0.79 ng/mL and 1.06 ng/mL; P < 0.01).

CONCLUSIONS

miR-30b milk displays significant changes in bioactive components associated with neonatal duodenal integrity and maturation, which could be involved in the earlier intestinal closure phenotype of the wild-type pups associated with a lower growth rate.

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.

Aryl hydrocarbon receptor utilises cellular zinc signals to maintain the gut epithelial barrier

Zinc and plant-derived ligands of the aryl hydrocarbon receptor (AHR) are dietary components affecting intestinal epithelial barrier function. Here, we explore whether zinc and the AHR pathway are linked. We show that dietary supplementation with an AHR pre-ligand offers protection against inflammatory bowel disease in a mouse model while protection fails in mice lacking AHR in the intestinal epithelium. AHR agonist treatment is also ineffective in mice fed zinc depleted diet. In human ileum organoids and Caco-2 cells, AHR activation increases total cellular zinc and cytosolic free Zn2+ concentrations through transcription of genes for zinc importers. Tight junction proteins are upregulated through zinc inhibition of nuclear factor kappa-light-chain-enhancer and calpain activity. Our data show that AHR activation by plant-derived dietary ligands improves gut barrier function at least partly via zinc-dependent cellular pathways, suggesting that combined dietary supplementation with AHR ligands and zinc might be effective in preventing inflammatory gut disorders.

Zinc-Rutin Particles Ameliorate DSS-Induced Acute and Chronic Colitis via Anti-inflammatory and Antioxidant Protection of the Intestinal Epithelial Barrier

In patients suffering from inflammatory bowel diseases (IBDs), the immune system is disrupted and the intestinal barrier function is compromised. Here, six zinc-flavonoid particles were produced by one-step reaction via changing flavonoids (myricetin, quercetin, and rutin) and solvent (water and ethanol), and then their cytocompatibility and ability to scavenge H2O2, free radicals, and LPS-induced ROS were compared. Zinc-rutin particles (W-ZnRT) composed of rutin (78.92 wt %), Na12[ZnPO4]12·12H2O (6.76 wt %), and crystal water were screened out because W-ZnRT exhibited 80.8 ± 15% cell viability against RAW264.7, could rapidly scavenge 78.1 ± 1% of H2O2 and 71.6 ± 2% of DPPH within 30 min, and reduced LPS-increased intracellular ROS to normal levels. In addition, the therapeutic effects of rutin and W-ZnRT were also compared in dextran sulfate sodium (DSS)-induced acute and chronic colitis in mice. W-ZnRT was superior to rutin alone in chronic colitis (n = 9), although they were equally effective in acute colitis (n = 7). Compared to rutin, 11 oral doses of W-ZnRT (40 mg kg-1) significantly improved intestinal permeability (p = 0.0299) and colon length (p = 0.0025), reduced intestinal proinflammatory factors (IL-6, IL-1β, and TNF-α), and upregulated tight junction proteins to maintain intestinal barrier function. Taken together, these results identified W-ZnRT as an efficient and safe therapeutic strategy for IBD.

Critical Signaling Transduction Pathways and Intestinal Barrier: Implications for Pathophysiology and Therapeutics

The intestinal barrier is a sum of the functions and structures consisting of the intestinal mucosal epithelium, mucus, intestinal flora, secretory immunoglobulins, and digestive juices. It is the first-line defense mechanism that resists nonspecific infections with powerful functions that include physical, endocrine, and immune defenses. Health and physiological homeostasis are greatly dependent on the sturdiness of the intestinal barrier shield, whose dysfunction can contribute to the progression of numerous types of intestinal diseases. Disorders of internal homeostasis may also induce barrier impairment and form vicious cycles during the response to diseases. Therefore, the identification of the underlying mechanisms involved in intestinal barrier function and the development of effective drugs targeting its damage have become popular research topics. Evidence has shown that multiple signaling pathways and corresponding critical molecules are extensively involved in the regulation of the barrier pathophysiological state. Ectopic expression or activation of signaling pathways plays an essential role in the process of shield destruction. Although some drugs, such as molecular or signaling inhibitors, are currently used for the treatment of intestinal diseases, their efficacy cannot meet current medical requirements. In this review, we summarize the current achievements in research on the relationships between the intestinal barrier and signaling pathways. The limitations and future perspectives are also discussed to provide new horizons for targeted therapies for restoring intestinal barrier function that have translational potential.

Sucrose-induced hyperglycemia dysregulates intestinal zinc metabolism and integrity: risk factors for chronic diseases

Objective

Zinc is an essential micronutrient that is critical for many physiological processes, including glucose metabolism, regulation of inflammation, and intestinal barrier function. Further, zinc dysregulation is associated with an increased risk of chronic inflammatory diseases such as type II diabetes, obesity, and inflammatory bowel disease. However, whether altered zinc status is a symptom or cause of disease onset remains unclear. Common symptoms of these three chronic diseases include the onset of increased intestinal permeability and zinc dyshomeostasis. The specific focus of this work is to investigate how dietary sources of intestinal permeability, such as high sucrose consumption, impact transporter-mediated zinc homeostasis and subsequent zinc-dependent physiology contributing to disease development.

Method

We used in vivo subchronic sucrose treatment, ex vivo intestinal organoid culture, and in vitro cell systems. We analyze the alterations in zinc metabolism and intestinal permeability and metabolic outcomes.

Results

We found that subchronic sucrose treatment resulted in systemic changes in steady-state zinc distribution and increased 65Zn transport (blood-to-intestine) along with greater ZIP14 expression at the basolateral membrane of the intestine. Further, sucrose treatment enhanced cell survival of intestinal epithelial cells, activation of the EGFR-AKT-STAT3 pathway, and intestinal permeability.

Conclusion

Our work suggests that subchronic high sucrose consumption alters systemic and intestinal zinc homeostasis linking diet-induced changes in zinc homeostasis to the intestinal permeability and onset of precursors for chronic disease.

ZnUMBA - a live imaging method to detect local barrier breaches

Epithelial barrier function is commonly analyzed using transepithelial electrical resistance, which measures ion flux across a monolayer, or by adding traceable macromolecules and monitoring their passage across the monolayer. Although these methods measure changes in global barrier function, they lack the sensitivity needed to detect local or transient barrier breaches, and they do not reveal the location of barrier leaks. Therefore, we previously developed a method that we named the zinc-based ultrasensitive microscopic barrier assay (ZnUMBA), which overcomes these limitations, allowing for detection of local tight junction leaks with high spatiotemporal resolution. Here, we present expanded applications for ZnUMBA. ZnUMBA can be used in Xenopus embryos to measure the dynamics of barrier restoration and actin accumulation following laser injury. ZnUMBA can also be effectively utilized in developing zebrafish embryos as well as cultured monolayers of Madin-Darby canine kidney (MDCK) II epithelial cells. ZnUMBA is a powerful and flexible method that, with minimal optimization, can be applied to multiple systems to measure dynamic changes in barrier function with spatiotemporal precision.

A novel 4-cell in-vitro blood-brain barrier model and its characterization by confocal microscopy and TEER measurement

The blood-brain barrier (BBB) is a protective cellular anatomical layer with a dynamic micro-environment, tightly regulating the transport of materials across it. To achieve in-vivo characteristics, an in-vitro BBB model requires the constituent cell types to be layered in an appropriate order. A cost-effective in-vitro BBB model is desired to facilitate central nervous system (CNS) drug penetration studies. Enhanced integrity of tight junctions observed during the in-vitro BBB establishment and post-experiment is essential in these models. We successfully developed an in-vitro BBB model mimicking the in-vivo cell composition and a distinct order of seeding primary human brain cells. Unlike other in-vitro BBB models, our work avoids the need for pre-coated plates for cell adhesion and provides better cell visualization during the procedure. We found that using bovine collagen-I coating, followed by bovine fibronectin coating and poly-L-lysine coating, yields better adhesion and layering of cells on the transwell membrane compared to earlier reported use of collagen and poly-L-lysine only. Our results indicated better cell visibility and imaging with the polyester transwell membrane as well as point to a higher and more stable Trans Endothelial Electrical Resistance values in this plate. In addition, we found that the addition of zinc induced higher claudin 5 expressions in neuronal cells. Dolutegravir, a drug used in the treatment of HIV, is known to appear in moderate concentrations in the CNS. Thus, dolutegravir was used to assess the functionality of the final model and cells. Using primary cells and an in-house coating strategy substantially reduces costs and provides superior imaging of cells and their tight junction protein expression. Our 4-cell-based BBB model is a suitable experimental model for the drug screening process.

The effects of arginine and branched-chain amino acid supplementation to reduced-protein diet on intestinal health, cecal short-chain fatty acid profiles, and immune response in broiler chickens challenged with Eimeria spp

We investigated the effects of supplementing arginine (Arg) and branched-chain amino acids (BCAA) in broilers fed reduced-protein diets and challenged with Eimeria spp. All birds were fed the same starter diet meeting Cobb 500 nutrient specifications from d 1 to 9. Four grower diets: positive control (PC) with 20.0% crude protein (CP); reduced-protein negative control (NC) with 17.5% CP; or NC supplemented with Arg or BCAA at 50% above recommendations (ARG or BCAA) were fed to the birds from d 9 to 28. Birds were allocated in a 2 × 4 factorial arrangement (4 diets, each with or without challenge), with 8 replicates per treatment. On d 14, the challenge groups were orally gavaged with mixed Eimeria spp. Intestinal permeability was higher (P < 0.05) in NC than PC, whereas the permeability of ARG and BCAA groups did not differ significantly from PC. On d 28, a significant interaction (P < 0.01) was observed in CD8⁺: CD4⁺ ratios in cecal tonsils (CT), Eimeria challenge increased the ratios in all groups except for the ARG group. On d 21, a significant interaction was found for CD4⁺CD25⁺ percentages in CT (P < 0.01) that Eimeria challenge increased the percentages only in PC and NC groups. On d 21 and 28, significant interactions (P < 0.01) were found for macrophage nitric oxide (NO) production. In nonchallenged birds, NO was higher in the ARG group than other groups, but in challenged birds, NO was higher in both ARG and BCAA groups. On d 21, a significant interaction was found for bile anticoccidial IgA concentrations (P < 0.05) that Eimeria challenge increased IgA only in NC and ARG groups. The results suggest that a reduced-protein diet exacerbates the impact of the Eimeria challenge on intestinal integrity, but this could be mitigated by Arg and BCAA supplementations. Arginine and BCAA supplementations in reduced-protein diets could be beneficial for broilers against Eimeria infection by enhancing the immune responses. The beneficial effects of Arg supplementation tended to be more pronounced compared to BCAA supplementation.

Enterocyte-specific deletion of metal transporter Zip14 (Slc39a14) alters intestinal homeostasis through epigenetic mechanisms

Zinc has anti-inflammatory properties using mechanisms that are unclear. Zip14 (Slc39a14) is a zinc transporter induced by proinflammatory stimuli and is highly expressed at the basolateral membrane of intestinal epithelial cells (IECs). Enterocyte-specific Zip14 ablation (Zip14ΔIEC) in mice was developed to study the functions of this transporter in enterocytes. This gene deletion led to increased intestinal permeability, increased IL-6 and IFNγ expression, mild endotoxemia, and intestinal dysbiosis. RNA sequencing was used for transcriptome profiling. These analyses revealed differential expression of specific intestinal proinflammatory and tight junction (TJ) genes. Binding of transcription factors, including NF-κβ, STAT3, and CDX2, to appropriate promoter sites of these genes supports the differential expression shown with chromatin immunoprecipitation assays. Total histone deacetylase (HDAC), and specifically HDAC3, activities were markedly reduced with Zip14 ablation. Intestinal organoids derived from ΔIEC mice display TJ and cytokine gene dysregulation compared with control mice. Differential expression of specific genes was reversed with zinc supplementation of the organoids. We conclude that zinc-dependent HDAC enzymes acquire zinc ions via Zip14-mediated transport and that intestinal integrity is controlled in part through epigenetic modifications.NEW & NOTEWORTHY We show that enterocyte-specific ablation of zinc transporter Zip14 (Slc39a14) results in selective dysbiosis and differential expression of tight junction proteins, claudin 1 and 2, and specific cytokines associated with intestinal inflammation. HDAC activity and zinc uptake are reduced with Zip14 ablation. Using intestinal organoids, the expression defects of claudin 1 and 2 are resolved through zinc supplementation. These novel results suggest that zinc, an essential micronutrient, influences gene expression through epigenetic mechanisms.

Dietary Zinc Glycine Supplementation Improves Tibia Quality of Meat Ducks by Modulating the Intestinal Barrier and Bone Resorption

Leg problems characterized by gait abnormity and bone structure destruction are associated with a high risk of fractures and continuous pain in poultry. Zinc (Zn) acts a pivotal part in normal bone homeostasis and has proven to be highly effective in alleviating leg problems. Therefore, the effects of graded concentration of Zn on bone quality were evaluated in this study. A total of 512 1-d-old male ducks were fed 4 basal diets added 30 mg/kg Zn, 60 mg/kg Zn, 90 mg/kg Zn, and 120 mg/kg Zn as Zn glycine for 35 d. Tibia Zn content, ash percentage, and breaking strength linearly increased with dietary elevated Zn level (P < 0.05). Broken-line analysis revealed that the recommended level of Zn from Zn glycine was 55.13 mg/kg and 64.48 mg/kg based on tibia ash and strength, respectively. To further confirm the role of dietary Zn glycine addition on bone characteristics, data from birds fed either 60 mg/kg Zn as Zn sulfate (ZnSO₄), 30 mg/kg Zn, or 60 mg/kg Zn in the form of Zn glycine indicated that birds given 60 mg/kg Zn from Zn glycine diet exhibited higher tibia ash, strength, and trabecular volume compared to those fed the 30 mg/kg Zn diet (P < 0.05). Dietary 60 mg/kg Zn as Zn glycine addition decreased intestinal permeability, upregulated the mRNA expression of tight junction protein, and increased the abundance of Lactobacillus and Bifidobacterium, which was companied by declined the level of inflammatory cytokines in both the ileum and bone marrow. Regarding bone turnover, the diet with 60 mg/kg Zn from Zn glycine induced osteoprotegerin expression and thus decreased osteoclast number and serum bone resorption biomarker levels including serum tartrate-resistant acid phosphatase activity and C-terminal cross-linked telopeptide of type I collagen level when compared to 30 mg/kg Zn diet (P < 0.05). Except for the upregulation in runt-related transcription factor 2 transcription, the experimental treatments did not apparently change the bone formation biomarker contents in serum. Additionally, Zn glycine displayed a more efficient absorption rate, evidenced by higher serum Zn level, and thus had potentially greater a protective role in the intestine barrier and tibia mass as compared to ZnSO₄. Collectively, the dietary supplementation of 60 mg/kg in the form of Zn glycine could suppress bone resorption mediated by osteoclast and consequently improve tibial quality of meat ducks, in which enhanced intestinal integrity and optimized gut microbiota might be involved.

Dietary trace mineral pattern influences gut microbiota and intestinal health of broilers

Dietary trace minerals can impact gut flora, which can further affect intestinal health. However, the dietary balance pattern of trace minerals for the intestinal health of broilers needs to be explored. The present study was conducted to investigate the effect of the dietary pattern of Cu, Fe, Mn, Zn, and Se on the intestinal morphology, microbiota, short-chain fatty acid concentrations, antioxidant status, and the expression of tight junction proteins in broilers. A total of 240 1-d-old Arbor Acres male broilers were randomly assigned to one of five treatments with six replicate cages of eight birds per cage for each treatment. The birds were fed the corn-soybean meal basal diet supplemented with five combination patterns of trace minerals for 42 d. The dietary treatments were as follows: the inorganic sources were added to the diet based on the recommendations of the current National Research Council (NRC, T1) and Ministry of Agriculture of P.R. China (MAP) (T2) for broiler chicks, respectively; the inorganic sources were added to the diet at the levels based on our previous results of inorganic trace mineral requirements for broilers (T3); the organic sources were added to the diet at the levels considering the bioavailabilities of organic trace minerals for broilers described in our previous studies (T4); and the organic sources were added to the diet based on the recommendations of the current MAP for broiler chicks (T5). The results showed that broilers from T1 had lower (P < 0.05) crypt depth (CD), and a higher (P < 0.05) villus height: CD in duodenum on day 21 and lower CD (P < 0.05) in jejunum on day 42 than those from T3 and T4. Broilers from T1, T3, and T5 had a higher (P < 0.05) Shannon index in cecum on day 21 than those from T4. Broilers from T1 had a higher (P < 0.05) abundance of Lactobacillus in ileum on day 21 than those from T2 and T3. Broilers from T1, T2, and T5 had a higher (P < 0.05) valeric acid concentrations in cecum on day 42 than those from T3 and T4. In addition, Birds from T2 had higher (P < 0.05) Claudin-1 mRNA levels in jejunum on day 42 than those from T3 and T4. And birds from T3, T4, and T5 had a higher (P < 0.05) Occludin protein expression levels in duodenum on day 42 than those from T2. These results indicate that dietary pattern of Cu, Fe, Mn, Zn, and Se influenced gut flora and intestinal health of broilers, and the appropriate pattern of Cu, Fe, Mn, Zn, and Se in the diet for intestinal health of broilers would be Cu 12 mg, Fe 229 mg, Mn 81 mg, Zn 78 mg, and Se 0.24 mg/kg (1 to 21 d of age), and Cu 11 mg, Fe 193 mg, Mn 80 mg, Zn 73 mg, and Se 0.22 mg/kg (22 to 42 d of age), when the trace minerals as inorganic sources were added to diets according to the recommendations of the current NRC.

Determination of the optimal dietary zinc content for pigs between 10 and 30 kg body weight

The Zn requirement of pigs immediately after weaning is more investigated compared to the Zn requirement in the growth period between 10 and 30 kg. Unabsorbed and excessive dietary Zn is excreted mainly through feces, and spreading pig slurry to fields can cause environmental issues because high levels of Zn can impair plant growth and contribute to the development of antimicrobial resistance genes in microorganisms. Therefore, more precise knowledge of Zn requirements and dietary Zn recommendations is important. The present study investigated the optimal dietary Zn content for 10- to 30-kg pigs. The study used 150 pigs weaned at 28 d of age (day 0) and supplied with 1,474 mg dietary Zn/kg the first 2 wk post-weaning. After 2 wk, pigs were randomly distributed according to body weight (BW; 10.1 ± 0.3 kg) and sex, to individually housing, and fed a diet supplemented with either 0, 30, 60, 120, or 240 mg Zn/kg (from ZnO), resulting in total dietary Zn contents of 80, 92, 117, 189, and 318 mg/kg until week 6 post-weaning. BW, feed intake, and fecal scores were recorded, and samples of blood (weeks 2, 3, 5, and 6) and tissues (week 6) were collected. The feed intake, growth, feed efficiency, relative weight of the pancreas and liver, Zn concentration in the liver, and pancreatic digestive enzyme activity were unaffected by dietary Zn content (P > 0.12). The serum Zn level decreased (P < 0.01) by up to 24% from weeks 2 to 3. The serum Zn concentrations in weeks 5 and 6 were similar to in week 2 when 117, 189, and 318 mg Zn/kg were provided, while with 80 and 92 mg Zn/kg the serum Zn concentration was lower (P < 0.01) than in week 2. The serum Zn concentration reached a plateau in weeks 5 and 6, and breakpoints were calculated at 126 ± 17 and 102 ± 6 mg Zn/kg, respectively. Bone Zn status was greater (P < 0.01) with 189 than 80 mg Zn/kg and a breakpoint was calculated at 137 ± 19 mg Zn/kg. According to performance, the Zn requirement for 10- to 30-kg pigs can be fulfilled with 80 mg total Zn/kg, but based on serum and bone Zn status, the optimal total dietary Zn content is 102 to 137 mg/kg. The latter corresponds to a daily Zn intake (requirement) of 103 to 138 mg when calculated from the average feed intake during weeks 3 to 6 (1,005 g/d). Importantly, the presented results are obtained in pigs supplied with 1,474 mg Zn/kg from ZnO the first 2 wk post-weaning and a high level of phytase (1,000 phytase units) in the diet throughout the experiment.

Human Milk Exosomes Induce ZO-1 Expression via Inhibition of REDD1 Expression in Human Intestinal Epithelial Cells

Human milk exosomes (HMEs) enhance intestinal barrier function and contribute to an improvement in inflammation and mucosal injury, such as necrotizing enteritis (NEC), in infants. Here, we aimed to elucidate the intracellular factors involved in HME-induced expression of zonula occludens-1 (ZO-1), a tight junction protein, in Caco-2 human intestinal epithelial cells. HME treatment for 72 h significantly increased transepithelial electrical resistance in these cells. The mean ZO-1 protein levels in cells treated with HME for 72 h were significantly higher than those in the control cells. The mRNA and protein levels of regulated in development and DNA damage response 1 (REDD1) in HME-treated cells were significantly lower than those in the control cells. Although HME treatment did not increase the mechanistic target of rapamycin (mTOR) level in Caco-2 cells, it significantly increased the phosphorylated mTOR (p-mTOR) level and p-mTOR/mTOR ratio. The ZO-1 protein levels in cells treated with an inducer of REDD1, cobalt chloride (CoCl₂) alone were significantly lower than those in the control cells. However, ZO-1 protein levels in cells co-treated with HME and CoCl₂ were significantly higher than those in cells treated with CoCl₂ alone. Additionally, REDD1 protein levels in cells treated with CoCl₂ alone were significantly higher than those in the control cells. However, REDD1 protein levels in cells co-treated with HME and CoCl₂ were significantly lower than those in cells treated with CoCl₂ alone. This HME-mediated effect may contribute to the development of barrier function in the infant intestine and protect infants from diseases.

Protective Mechanism of Ethyl Gallate against Intestinal Ischemia-Reperfusion Injury in Mice by in Vivo and in Vitro Studies Based on Transcriptomics

Intestinal ischemia-reperfusion injury (IIRI) is a common clinical disease that can be life-threatening in severe cases. This study aimed to investigate the effects of ethyl gallate (EG) on IIRI and its underlying mechanisms. A mouse model was established to mimic human IIRI by clamping the superior mesenteric artery. Transcriptomics techniques were used in conjunction with experiments to explore the potential mechanisms of EG action. Intestinal histomorphological damage, including intestinal villi damage and mucosal hemorrhage, was significantly reversed by EG. EG also alleviated the oxidative stress, inflammation, and intestinal epithelial apoptosis caused by IIRI. 2592 up-regulated genes and 2754 down-regulated genes were identified after EG treatment, and these differential genes were enriched in signaling pathways, including fat digestion and absorption, and extracellular matrix (ECM) receptor interactions. In IIRI mouse intestinal tissue, expression of the differential protein matrix metalloproteinase 9 (MMP9), as well as its co-protein NF-κB-p65, was significantly increased, while EG inhibited the expression of MMP9 and NF-κB-p65. In Caco-2 cells in an established oxygen-glucose deprivation/reperfusion model (OGD/R), EG significantly reversed the decrease in intestinal barrier trans-epithelial electrical resistance (TEER). However, in the presence of MMP9 inhibitors, EG did not reverse the decreasing trend in TEER. This study illustrates the protective effect and mechanism of action of EG on IIRI and, combined with in vivo and in vitro experiments, it reveals that MMP9 may be the main target of EG action. This study provides new scientific information on the therapeutic effects of EG on IIRI.

18β-Glycyrrhetinic acid altered the intestinal permeability in the human Caco-2 monolayer cell model

PURPOSE

Glycyrrhizin (GL) and its metabolites 18α-glycyrrhetinic acid (18α-GA) and 18β-glycyrrhetinic acid (18β-GA) are used as traditional medicine and food sweeteners. As the major rout of their administration is oral way, therefore their impact on intestinal epithelial cells are investigated.

METHODS

The effects of GL and its metabolites on cell viability using MTT assay, on cytotoxicity using LDH release, on integrity of intestinal epithelial cells by measuring the transepithelial electrical resistance (TEER) and Luciferase permeability tests, on the expression of tight junction proteins at mRNA and protein level by qPCR and western blot techniques, and ultimately on the rate of test compounds absorption via Caco-2 cells monolayer were investigated.

RESULTS

MTT assay showed a concentration- and time-dependent decrease in metabolic activity of Caco-2 cells induced by GL, 18α-GA, and 18β-GA, while only 18β-GA increased the LDH leakage. The monolayer integrity of Caco-2 cells in TEER assay only was affected by 18β-GA. The permeability of paracellular transport marker was increased by 18α-GA and 18β-GA and not GL. In transport studies, only metabolites were able to cross from Caco-2 cells monolayer. qPCR analyses revealed that 18β-GA upregulated the expression of claudin-1 and -4, occludin, junctional adhesion molecules and zonula occludens-1, while 18α-GA upregulated only claudin-4. The expression of claudin-4 at protein level was downregulated non-significantly at 50 μM concentration of 18β-GA.

CONCLUSION

Our results suggest that 18β-GA may cause cellular damages at higher concentrations on gastrointestinal cells and requires a remarkable attention of the nutraceutical and pharmaceutical industries.

The Assessment of Dietary Organic Zinc on Zinc Homeostasis, Antioxidant Capacity, Immune Response, Glycolysis and Intestinal Microbiota in White Shrimp (Litopenaeus vannamei Boone, 1931)

This study aimed to assess dietary organic zinc on zinc homeostasis, antioxidant capacity, immune response, glycolysis and intestinal microbiota in white shrimp (Litopenaeus vannamei Boone, 1931). Six experimental diets were formulated: Control, zinc free; S120, 120 mg·kg-1 zinc from ZnSO4·7H2O added into control diet; O30, O60, O90 and O120, 30, 60, 90 and 120 mg·kg-1 zinc from Zn-proteinate added into control diet, respectively. The results showed that organic zinc significantly promoted zinc content and gene expression of ZnT1, ZIP11 and MT in the hepatopancreas and enhanced antioxidant capacity and immunity (in terms of increased activities of T-SOD, Cu/Zn SOD, PO, LZM, decreased content of MDA, upregulated expressions of GST, G6PDH, ProPO, LZM and Hemo, and increased resistance to Vibrio parahaemolyticus). Organic zinc significantly upregulated GluT1 expression in the intestine, increased glucose content of plasma and GCK, PFK and PDH activities of hepatopancreas, and decreased pyruvate content of hepatopancreas. Organic zinc improved intestinal microbiota communities, increased the abundance of potentially beneficial bacteria and decreased the abundance of potential pathogens. Inorganic zinc (S120) also had positive effects, but organic zinc (as low as O60) could achieve better effects. Overall, organic zinc had a higher bioavailability and was a more beneficial zinc resource than inorganic zinc in shrimp feeds.

The Impact of Zinc and Zinc Homeostasis on the Intestinal Mucosal Barrier and Intestinal Diseases

Zinc is an essential trace element for living organisms, and zinc homeostasis is essential for the maintenance of the normal physiological functions of cells and organisms. The intestine is the main location for zinc absorption and excretion, while zinc and zinc homeostasis is also of great significance to the structure and function of the intestinal mucosal barrier. Zinc excess or deficiency and zinc homeostatic imbalance are all associated with many intestinal diseases, such as IBD (inflammatory bowel disease), IBS (irritable bowel syndrome), and CRC (colorectal cancer). In this review, we describe the role of zinc and zinc homeostasis in the intestinal mucosal barrier and the relevance of zinc homeostasis to gastrointestinal diseases.

Activation of the zinc-sensing receptor GPR39 promotes T-cell reconstitution after hematopoietic cell transplant in mice

Prolonged lymphopenia represents a major clinical problem after cytoreductive therapies such as chemotherapy and the conditioning required for hematopoietic stem cell transplant (HCT), contributing to the risk of infections and malignant relapse. Restoration of T-cell immunity depends on tissue regeneration in the thymus, the primary site of T-cell development, although the capacity of the thymus to repair itself diminishes over its lifespan. However, although boosting thymic function and T-cell reconstitution is of considerable clinical importance, there are currently no approved therapies for treating lymphopenia. Here we found that zinc (Zn) is critically important for both normal T-cell development and repair after acute damage. Accumulated Zn in thymocytes during development was released into the extracellular milieu after HCT conditioning, where it triggered regeneration by stimulating endothelial cell production of BMP4 via the cell surface receptor GPR39. Dietary supplementation of Zn was sufficient to promote thymic function in a mouse model of allogeneic HCT, including enhancing the number of recent thymic emigrants in circulation although direct targeting of GPR39 with a small molecule agonist enhanced thymic function without the need for prior Zn accumulation in thymocytes. Together, these findings not only define an important pathway underlying tissue regeneration but also offer an innovative preclinical approach to treat lymphopenia in HCT recipients.

The role of orally ingested milk fat globule membrane on intestinal barrier functions evaluated with a suckling rat pup supplementation model and a human enterocyte model

Milk fat globule membrane (MFGM), the membrane surrounding secreted fat droplets in milk, contains components involved in a wide range of bioprocesses including cell proliferation and differentiation. The intestine is relatively immature and permeable at birth. Since MFGM is partly resistant to digestion in infancy, we hypothesized that orally ingested MFGM promotes intestinal development by enhancing intestinal barrier functions in early life. An established suckling rat model was used; Sprague-Dawley rats were bred, and litters were culled to 10 pups/dam. Pups were supplemented orally with MFGM (0, 100, or 300 mg/kg/day) from postnatal day 1 to 20. Intestine samples were collected for histology, qRT-PCR, immunoblotting, and immunohistochemistry analysis. Additionally, differentiated Caco-2 cells were used to assess effects of MFGM on the human intestinal barrier. Control and MFGM-supplemented rat pups showed similar growth. Intestinal differentiation and expression of tight junction proteins in jejunum and colon were significantly increased by orally ingested MFGM, and MFGM supplementation significantly activated PI3K/Akt/mTOR, MAPK, and MLCK signaling pathways, suggesting that MFGM promotes intestinal development by triggering various signaling pathways. In human enterocytes (polarized Caco-2 cells), MFGM (400 µg/mL for 72 h) decreased permeability, as revealed by increased transepithelial electrical resistance. In Caco-2 cells, MFGM also enhanced expression of tight junction proteins, including claudin-4 and ZO-2. In conclusion, orally ingested MFGM may exert beneficial roles in intestinal development by activating various cell signaling pathways to upregulate tight junction proteins and thereby increasing intestinal barrier functions.

Babies, Bugs, and Barriers: Dietary Modulation of Intestinal Barrier Function in Early Life

The intestinal barrier is essential in early life to prevent infection, inflammation, and food allergies. It consists of microbiota, a mucus layer, an epithelial layer, and the immune system. Microbial metabolites, the mucus, antimicrobial peptides, and secretory immunoglobulin A (sIgA) protect the intestinal mucosa against infection. The complex interplay between these functionalities of the intestinal barrier is crucial in early life by supporting homeostasis, development of the intestinal immune system, and long-term gut health. Exclusive breastfeeding is highly recommended during the first 6 months. When breastfeeding is not possible, milk-based infant formulas are the only safe alternative. Breast milk contains many bioactive components that help to establish the intestinal microbiota and influence the development of the intestinal epithelium and the immune system. Importantly, breastfeeding lowers the risk for intestinal and respiratory tract infections. Here we review all aspects of intestinal barrier function and the nutritional components that impact its functionality in early life, such as micronutrients, bioactive milk proteins, milk lipids, and human milk oligosaccharides. These components are present in breast milk and can be added to milk-based infant formulas to support gut health and immunity. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.