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From immature to mature epithelium: unveiling structural dynamics and transcriptional programs in rainbow trout intestinal barrier.

The intestinal epithelium is crucial for nutrient absorption, immune defense, and barrier function in farmed fish. However, the molecular mechanisms underlying its development and maturation in salmonids remain poorly characterized, hindering our ability to address pervasive gut health challenges in aquaculture. In this study, we use the RTgutGC cell line to implement an epithelial maturation model with the aim of characterizing the global transcriptional program in rainbow trout (Oncorhynchus mykiss). We evaluated in vitro culture conditions to generate a polarized epithelial barrier with high transepithelial electrical resistance (TEER = 75.8 Ω × cm2), low permeability (6.2 × 10-6 cm/s), and well-defined apical specializations, including microvilli-like structures and clusters of these structures (brush border). Comparative transcriptomic profiling between immature (7 days post-seeding, dps) and mature (28 dps) epithelia revealed 3,817 differentially expressed genes (DEGs). Functional enrichment analysis showed that maturation was characterized by the downregulation of proliferative and ribosomal pathways and the concerted upregulation of processes critical for barrier function, including transmembrane transport, proteolysis, cell adhesion, extracellular matrix organization, and tight junction assembly. We identified a core set of 60 genes indicators of epithelial maturation, encompassing solute transporters (slc26a6, slc43a2), tight junction proteins (tjp1, cldn1, cldn3, cldn5, cldn18, among others), and structural components essential for microvilli formation and polarization (cdhr5b, pard6a). By integrating ultrastructural, functional, and transcriptomic data, this study established a framework for future mechanistic investigations into gut development and maturation in vitro. This set of mature epithelium indicators has diverse applications, such as the design of nutritional and pharmacological interventions to improve gut health and resilience in farmed fish.

Animals

Increasing gut short-chain fatty acids protects intestinal barrier function but does not spare muscle glycogen or impact aerobic performance.

Animal studies suggest gut microbiota-derived short-chain fatty acids (SCFA) provide an intestinal barrier-protecting, glycogen-sparing energy source that increases aerobic endurance performance, but confirmation in humans is needed. This study aimed to determine whether increasing colonic SCFA availability impacts intestinal barrier function, substrate metabolism, muscle glycogen and aerobic performance in healthy adults. Using a randomized, double-blind, crossover design 12 active men (age 18-30&#xa0;years;40.0&#xa0;&#xb1;&#xa0;7.1&#xa0;mL/kg/min) performed prescribed exercise and consumed a provided diet supplemented with acetylated and butyrylated high-amylose maize starch engineered to deliver SCFA to the colon (HAMS-A/B) or low-amylose maize starch (LAMS) for 7 days, separated by a 2 week washout. Indirect calorimetry, stable isotopes and blood, muscle and urine biomarkers were measured on intervention day 8 while participants completed 90&#xa0;min of steady-state cycle ergometry (ExSS; 60 &#xb1; 5%) followed by a 5&#xa0;km treadmill time trial. HAMS-A/B, relative to LAMS, increased faecal and serum SCFA. Multiple markers of intestinal barrier damage and permeability were lower, and the respiratory exchange ratio during ExSS was higher (0.02 [95% confidence interval (CI): 0.01, 0.03], Ptreatment&#xa0;<&#xa0;0.001) following HAMS-A/B versus LAMS. However no between-treatment difference in glucose turnover, muscle glycogen depletion (14&#xa0;&#xb5;mol/kg/g dry wt. [95% CI: -116, 143], Pinteractio n&#xa0;=&#xa0;0.613) or TT performance (5&#xa0;s [95%CI: -44, 54], Ptreatment&#xa0;=&#xa0;0.816) was observed. Increasing colonic and circulating SCFA modestly altered substrate oxidation and preserved intestinal barrier function during endurance exercise. However effects were not sufficient to spare muscle glycogen or increase aerobic endurance performance, leaving the practical relevance unclear and underscoring challenges inherent in translating promising preclinical findings to humans. KEY POINTS: Animal studies suggest gut microbiota-derived short-chain fatty acids (SCFA) provide an intestinal barrier-protecting, glycogen-sparing energy source that increases aerobic endurance performance, but confirmation in humans is lacking. A gut microbiota-targeted dietary supplementation strategy was used to deliver SCFA to the colon and successfully increased colonic and systemic SCFA concentrations in healthy, physically active adults before and during an endurance exercise bout and aerobic performance test. Increasing colonic and systemic SCFA availability preserved intestinal barrier function but did not impact glucose turnover, alter protein expression in muscle or spare muscle glycogen during endurance exercise. Increasing colonic and systemic SCFA availability did not impact aerobic endurance performance.

Humans

Intestinal barriers to water-soluble macromolecules.

Neonates of some species of mammals absorb water-soluble macromolecules from the lumen of the gut to the circulation. This is a means for providing the neonate with passive immunological protection. The accepted model for absorption of macromolecules, particularly immunoglobulin G (IgG), has at least three phases: adherence of the macromolecule to the brush border on enterocytes; internalization of the macromolecule within the enterocytes; and egress of the macromolecule into the lamina propria. With regard to the absorption of IgG, adherence is thought to be a specific reaction of ligand (IgG) with a plasmalemma binding site. Pinocytosis is activated and internalization follows. Egress into the lamina propria occurs at the basal-lateral membrane by a process of reverse pinocytosis. Unbound (unprotected) macromolecules that are internalized in the pinocytosic fluid are shunted off to lysosomes and either digested or stored therein. Neonatal rodents fit this model for macromolecular absorption. However, in another group of neonates (e.g., pig, cow, horse), nonselected absorption takes place, in that IgG and other macromolecules are transported from the gut lumen to the blood. In a third group of neonates, (e.g., human, guinea pig) absorption of IgG is either of low order or nonexistent. Since neonatal mammals possess a mechanism for absorbing macromolecules, there is the potential for internalizing toxic macromolecules if the toxin is presented to the neonate's enterocytes in competitive amounts. Adults retain remnants of the neonatal absorptive mechanism.

Adult

Kefir and Its By-Products Supplementation Reduces Inflammation and Oxidative Stress, Improves Intestinal Barrier Integrity, and Modulates the Gut Microbiota in Animal Models of Inflammatory Bowel Disease: A Systematic Review.

UNLABELLED: Kefir is a beverage obtained by fermenting milk or sugary solutions with a symbiotic community of bacteria and yeasts, presenting promising antimicrobial, antioxidant, and immunomodulatory properties. This systematic review aimed to synthesize evidence from preclinical studies evaluating the effects of kefir or its by-products on biomarkers of inflammation, oxidative stress, and gut health in animal models of IBD. A systematic review was conducted in accordance with PRISMA guidelines, utilizing the PubMed/MEDLINE, Web of Science, Embase, and Scopus databases. The quality of the studies was assessed using SYRCLE&#x2019;s Risk of Bias tool. Sixteen experimental studies were included, comprising 585 rodents with chemically induced colitis. The interventions included traditional milk kefir, rice and water kefir, as well as isolated microorganisms and kefir-derived supernatants. Most studies reported reductions in inflammatory cytokines (TNF-&#x3b1;, IL-1&#x3b2;, IL-6) and inflammatory enzymes (iNOS, COX-2, MPO), along with increases in anti-inflammatory cytokines (IL-10, IL-4). Reductions in MDA and H&#x2082;O&#x2082; were reported, supporting the antioxidant effects of kefir and its derivatives. Changes in antioxidant enzyme activity, including SOD, were also observed. In addition, kefir modulated gut microbiota composition, upregulated the expression of tight junction proteins, and influenced immune and molecular signaling pathways. Improvements were also observed in clinical parameters of IBD models, including disease activity index, rectal bleeding, and histological damage. Kefir and its derivatives exhibit beneficial effects on inflammation, oxidative stress, gut permeability, and immune modulation in animal models of IBD, suggesting a potential alternative for treating these diseases in humans. Although the findings are promising, heterogeneity among study protocols and methodological limitations highlight the need for further studies. Registration PROSPERO number: CRD420251062931. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s12602-026-10948-5.

Animal model

The intestinal mucosal barrier to intact antigenic protein. Difference between colon and small intestine.

The integrity of the normal mature intestinal mucosal barrier to unaltered proteins was evaluated with tritiated bovine albumin in rats. Intact H3-BSA placed into either colon or small intestinal lumen regularly reached the bloodstream in quantities sufficient to be antigenic or toxigenic, although the fraction of H3-BSA absorbed from the colon (0.13 per cent) was significantly smaller than that absorbed from the small intestine (1.7 per cent). These studies support the possibility that uptake of ingested or bacterial antigens from the normal gut may be involved in the pathogenesis of local intestinal and systemic disease in man.

Animals

Eagle-Derived Weissella confusa EG05 Prevents LPS-Induced Enteritis Through Modulation of Inflammation, Gut Barrier, And Microbiota.

Intestinal enteric inflammation can seriously harm animal health and lead to massive economic losses in livestock production. Probiotics have become a promising alternative to antibiotics for preventing and controlling enteritis. In this study, a novel lactic acid bacterium (LAB) was isolated from eagle feces and identified as Weissella confusa EG05 (W. confusa EG05), and its probiotic characteristics and protective effects on lipopolysaccharide (LPS)-induced enteritis in mice were evaluated. In vitro experiments showed that W. confusa EG05 has strong antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), good tolerance to acidic and bile salt conditions, high auto-aggregation ability and surface hydrophobicity, and no hemolytic activity. Whole-genome analysis further confirmed its safety and probiotic potential by revealing genes involved in adhesion, immune regulation, and stress tolerance. In mouse experiments, pretreatment with W. confusa EG05 alleviated LPS-induced intestinal pathological damage, inhibited the secretion of pro-inflammatory cytokines (TNF-&#x3b1;, IFN-&#x3b3;, IL-6), promoted the expression of anti-inflammatory cytokine IL-10, enhanced the activities of antioxidant enzymes, and up-regulated the expression of tight junction proteins (Occludin, ZO-1). In addition, W. confusa EG05 restored gut microbiota homeostasis disturbed by LPS, increasing the abundance of beneficial genera and decreasing harmful bacteria. Taken together, these results suggest that W. confusa EG05 can effectively prevent LPS-induced enteritis in mice by modulating the inflammatory response, enhancing antioxidant capacity, protecting the intestinal barrier and the reshaping gut microbiota. These results indicate that W. confusa EG05 exhibits prominent probiotic potential in mouse models, providing a strain resource for the future development of microecological preparations.

Weissella confusa EG05

Cetobacterium somerae ZNN-1 promotes goblet cell differentiation through glutamine-mediated Notch signaling suppression.

INTRODUCTION: The gut microbiota acts as a crucial mediator in the interaction between the diet components and the host metabolism. However, the molecular mechanism by which the gut microbiota adapts to dietary components and subsequently regulates host physiological responses remains unclear. OBJECTIVES: This study aimed to investigate the response of gut microbiota to a plant-based protein diet (soybean meal, SM) and the effects of gut microbiota on host intestinal barrier function, along with the underlying mechanisms in a fish model. METHODS: Histopathological examination, and transepithelial electrical resistance test were used to evaluate the effects of Cetobacterium somerae on intestinal barrier function. Potential molecular mechanisms were validated by integrating whole-genome sequencing, microbiota composition sequencing, transcriptomics, and metabolomics, and utilizing in vitro cell models and mouse-derived organoid models. RESULTS: The results revealed that the SM diet significantly increased the abundance of Cetobacterium somerae in fish. Administration of C.somerae ZNN-1, a dominant strain isolated from the intestine of fish fed with the SM diet, enhanced the intestinal barrier function, particularly increasing the number of goblet cells in the intestine. Whole genome analysis of C. somerae ZNN-1 showed carbohydrate metabolism-associated genes were the most abundant in its metabolic modules. C.somerae ZNN-1 supplementation significantly inhibited the Notch signaling pathway in fish intestine. Metabolomics analysis revealed that administration of C.somerae ZNN-1 increased the glutamine level in fish gut. In vitro experiments demonstrated that glutamine regulated the differentiation of goblet cell by inhibiting the Notch signaling pathway in both human intestinal epithelial cell model and mouse intestinal organoid model. CONCLUSION: C. somerae served as a key bacterium adapted to soybean meal-derived carbohydrates, and it promoted goblet cell differentiation by inhibiting the Notch pathway. This study provides a new perspective for unraveling the interaction mechanisms among diet components, intestinal microbiota and host health.

Animals

Long noncoding RNA GAS5 disrupts intestinal epithelial barrier function by increasing small vault RNA levels.

Disruptions in the integrity of the intestinal epithelium occur commonly in inflammatory bowel disease (IBD) and critical surgical disorders, but the underlying mechanisms remain largely unknown. Here we identified long noncoding RNA GAS5 as a repressor of intestinal mucosal growth and the function of the gut epithelial barrier. The levels of tissue GAS5/Gas5 increased in mouse intestinal mucosa after colitis and septic stress, as well as in human intestinal mucosa from patients with IBD. Transient and tissue-specific knockdown of Gas5 in mice using CRISPR/Cas9 enhanced the renewal of the mucosa of the small intestine, increased the levels of tight junction (TJ) proteins ZO-1, ZO-2, claudin-1, and claudin-2, and improved gut barrier function. Conversely, ectopic overexpression of GAS5 in intestinal organoids and in cultured intestinal epithelium cells decreased the levels of these TJ proteins and caused epithelial barrier dysfunction. Mechanistic studies revealed that GAS5 acted as a transcriptional enhancer of the gene (2. AUTHOR: Do you mean "genes"?) encoding small noncoding vault RNAs (vtRNAs) and that GAS5 repressed TJ expression by increasing the levels of vtRNAs. Together, our results indicate that GAS5 disrupts the integrity of the intestinal epithelium by impairing mucosal growth and epithelial barrier function and that it represses TJ expression, at least in part, via vtRNAs.

Animals

[Routes of E. coli 055 bacterial penetration through the intestinal wall in gnotobiotic and ordinary animals].

Peculiarities of permeability of intestinal barrier in germfree animals for enteropathogenic E. coli 055 were studied. Both germfree and conventional guinea pigs and rats were used. An increase of bacteriemia was revealed in gnotobiotes during the first day of oral E. coli 055 monocontamination; bacteriemia was transient in conventional animals. Under electron microscopy alterations of intercellular contacts and formation of spaces between enterocytes containing numerous microorganisms were found in the intestinal mucous membrane in gnotobiotes. Also more pronounced changes of microvessels of the intestinal mucous membrane were discovered in gnotobiotes. The processes of ingestionan and digestion of Escherichia coli by enterocytes and leukocytes were noted in conventional animals. The revealed derangements of the intestinal barrier in gnotobiotes explain the cause of higher bacteriemia in germfree animals. An important role of the microbial factor in the formation of intestinal barrier is indicated by the data obtained.

Animals

Opposite metabolic and gut responses to oral glutamine in male and female mice with diet-induced obesity.

Obesity is often associated with sex-dependent metabolic complications, to which altered intestinal barrier function and gut microbiota contribute. Glutamine supplementation has previously shown beneficial effects on gut barrier function and glycemic control. We thus aimed to characterize, in male and female mice, the effects of oral glutamine supplementation during high-fat-diet-induced obesity. Male and female C57BL/6 mice received a standard (SD) or high-fat diet (HFD; 60 % kcal from fat) for 14&#xa0;weeks (W14). From W12 onward, mice received glutamine in drinking water (2&#xa0;g/kg/day) or no supplementation. Body composition, glucose tolerance, insulin sensitivity, intestinal permeability, colonic inflammatory response, cecal microbiota and inflammatory/endocrine adipose response were assessed. In both male and female mice, glutamine supplementation failed to improve body weight and body composition. However, glutamine reduced glucose intolerance in HFD-fed males (AUC reduced by 14.57 %) that was associated with a partial restoration of plasma resistin and insulin and a trend toward limiting adipose inflammatory response. In males, glutamine did not affect gut microbiota composition and colonic response. Conversely, in HFD-fed females, glutamine supplementation led to gut microbiota changes (increase in Bacteroidota and Pseudomonadota phyla; increase in Muribaculaceae and Tannerellaceae families), increased colonic inflammatory markers (Il1b, Tlr4, Myd88, Irf3), increased inflammatory response in subcutaneous adipose tissue and increased HOMA-IR. Finally, HFD-fed mice exhibited sex-specific responses to glutamine supplementation with protective effects in males and harmful effects in females that need to be further deeply explored.

Animals

Probiotic-derived extracellular vesicles as food-based nanocarriers: Mechanisms, functional applications, and future perspectives in food systems.

Probiotic-derived extracellular vesicles (PDEVs) are a promising type of postbiotic nanoparticle derived by fermentation of probiotics, and have gained growing interest as a potential application in food science and nutrition. These are lipid bilayer vesicles of nanoscale, which are naturally released by probiotic cells and contain a wide variety of bioactive molecules, such as proteins, nucleic acids, and metabolites. Moreover, PDEVs are highly stable, biocompatible, and can be easily engineered to have surfaces with high functionality, which makes them good candidates in functional engineering. In contrast to traditional live probiotics, PDEVs overcome the difficulties of preserving microbial viability during processing and storage, thus providing superior safety, stability, and predictable biological performance. This is a systematic review of the various functions of PDEVs in food systems. We conclude on the processes through which PDEVs control intestinal barrier integrity, alter gut microbiota composition, and alter host immune responses, and their potential to enhance gut health when added to functional foods. In addition to their health-promoting effects, PDEVs have shown significant potential as natural antimicrobial agents to preserve food and as effective nanocarriers of hydrophobic bioactive compounds, including fucoxanthin, to improve their stability, bioavailability, and targeted delivery. Moreover, PDEVs can be used as new regulators of microbial fermentation. However, it should be noted that a lot of the evidence that is available is still preliminary and the effectiveness of these applications in real food-processing and storage conditions has not been fully proven. Although they have potential, there are a number of challenges that still hinder the widespread use of PDEVs in the food industry. These involve the creation of scalable and cost-effective production processes, batch-to-batch consistency, vesicle stability in a variety of food matrices, and regulatory and safety considerations. Other emerging engineering approaches, such as surface functionalization and cargo loading, are also discussed in this review and could further increase the specificity, functionality, and application versatility of PDEVs in food systems. Moving forward, the incorporation of PDEVs into the next generation functional foods, novel food preservation methods, and customized nutrition plans should be prioritized in future studies. Further developments in these fields can make PDEVs useful platforms at the interface of food microbiology, nanotechnology, and human health.

Probiotics

[Animal study on radioactive antigenic fractions isolated from V.cholerae. I. The Ch 1 + 2 fraction].

The Ch 1 + 2 fraction has been marked by means of culture of Vibrio cholerae Ogawa HK1 on a synthetic medium containing leucine H3. The antigen distribution has been then studied before and after vaccination with the same non-marked antigen in normal and axenic mice, at the same time by the demonstration of radioactivity and radioimmunofluorescence in intestine, spleen, liver, kidney and thymus. Whichever the administration route, intestine and spleen are first stimulated, then more intensively with the second injection or ingestion. When administrated per os the fraction crosses the intestinal barrier and is fixed on the main lymphoid organs: intestine, spleen, thymus. After ingestion or injection into axenic mice, spleen is the first organ stimulated.

Animals

[Mechanism of Tianshu Capsules in treating migraine rats based on gut microbiota].

This study aims to investigate the therapeutic effect of Tianshu Capsules(TS) on migraine rat model and explore its potential mechanism of action from the perspectives of the structure of the gut microbiota and functional pathway regulation. A migraine rat model was established via subcutaneous injection of nitroglycerin. The Sprague-Dawley rats were randomly divided into a control group, a model group, a low-dose TS group, a medium-dose TS group, a high-dose TS group, and an ibuprofen group. The efficacy of TS in improving migraine was evaluated by general condition observation and measurement of the craniofacial pain threshold. The expression of the gene c-fos in the trigeminal ganglion was determined by quantitative real-time polymerase chain reaction(PCR). The contents of endothelin-1(ET-1), calcitonin gene-related peptide(CGRP), and 5-hydroxytryptamine(5-HT) in serum were measured by enzyme-linked immunosorbent assay(ELISA). Fecal samples were subjected to metagenomic sequencing for systematic analysis of gut microbial diversity, taxonomic composition difference, and functional pathway changes of Kyoto Encyclopedia of Genes and Genomes(KEGG), and their correlations with behavioral and biochemical indices were further evaluated. The results show that TS significantly improves the increased body temperature and decreased craniofacial pain threshold in migraine rats. It also markedly suppresses the elevated expression levels of the gene c-fos in the trigeminal ganglion and reduces the levels of ET-1, CGRP, and 5-HT in serum. Metagenomic beta diversity analysis and differential taxonomic abundance analysis reveal that the migraine model induces significant gut microbiota dysbiosis, characterized by enrichment of harmful genera, including Streptococcus and Enterococcus, as well as a decline in the abundance of beneficial bacteria such as Allobaculum, Eubacterium, and Muribaculum. Functional pathway analysis results of KEGG further reveal that the relative abundances of pathways associated with biosynthesis of phenylalanine, tyrosine, and tryptophan, bacterial secretion system, citrate cycle, and biosynthesis of secondary metabolites are significantly decreased in the model group. TS intervention increased the abundance of the genus, such as Parabacteroides, Eubacterium, Allobaculum, and Muribaculum, while decreasing levels of microbiota, including Staphylococcus. TS also significantly upregulated pathways associated with barrier function(tight junction), amino acid biosynthesis pathways, and biosynthesis pathways of neurotransmitter precursors such as cysteine and methionine metabolism. In addition, it downregulated inflammatory pathways(Toll and IMD signaling) and pathways related to Staphylococcus aureus infection, thereby restoring the structure and function of the microbiota to a state close to those of the normal group. Spearman correlation analysis reveals that partial gut microbiota are significantly associated with migraine-related behavioral and biochemical indices(c-fos, ET-1, CGRP, and 5-HT). In conclusion, TS can regulate the disrupted gut microbiota structure and microbial functions related to neurotransmitter metabolism, intestinal barrier function, and inflammatory regulation in migraine model rats, which may be one of the potential key ways through which TS exert its anti-migraine effect.

Animals

Deficiency of IL-22-binding protein enhances the ability of the gut microbiota to protect against enteric pathogens.

Interleukin 22 (IL-22) promotes intestinal barrier integrity, stimulating epithelial cells to enact defense mechanisms against enteric infections, including the production of antimicrobial peptides. IL-22 binding protein (IL-22BP) is a soluble decoy encoded by the Il22ra2 gene that decreases IL-22 bioavailability, attenuating IL-22 signaling. The impact of IL-22BP on gut microbiota composition and functioning is poorly understood. We found that Il22ra2-/- mice are better protected against Clostridioides difficile and Citrobacter rodentium infections. This protection relied on IL-22-induced antimicrobial mechanisms before the infection occurred, rather than during the infection itself. Indeed, the gut microbiota of Il22ra2-/- mice mitigated infection of wild-type (WT) mice when transferred via cohousing or by cecal microbiota transplantation. Indicator species analysis of WT and Il22ra2-/- mice with and without cohousing disclosed that IL22BP deficiency yields a gut bacterial composition distinct from that of WT mice. Manipulation of dietary fiber content, measurements of intestinal short-chain fatty acids and oral treatment with acetate disclosed that resistance to C. difficile infection is related to increased production of acetate by Il22ra2-/--associated microbiota. Together, these findings suggest that IL-22BP represents a potential therapeutic target for those at risk for or with already manifest infection with this and perhaps other enteropathogens.

Animals

Crohn's disease.

Crohn's disease is a relapsing systemic inflammatory disease, mainly affecting the gastrointestinal tract with extraintestinal manifestations and associated immune disorders. Genome wide association studies identified susceptibility loci that--triggered by environmental factors--result in a disturbed innate (ie, disturbed intestinal barrier, Paneth cell dysfunction, endoplasmic reticulum stress, defective unfolded protein response and autophagy, impaired recognition of microbes by pattern recognition receptors, such as nucleotide binding domain and Toll like receptors on dendritic cells and macrophages) and adaptive (ie, imbalance of effector and regulatory T cells and cytokines, migration and retention of leukocytes) immune response towards a diminished diversity of commensal microbiota. We discuss the epidemiology, immunobiology, amd natural history of Crohn's disease; describe new treatment goals and risk stratification of patients; and provide an evidence based rational approach to diagnosis (ie, work-up algorithm, new imaging methods [ie, enhanced endoscopy, ultrasound, MRI and CT] and biomarkers), management, evolving therapeutic targets (ie, integrins, chemokine receptors, cell-based and stem-cell-based therapies), prevention, and surveillance.

Colonic Diseases

[Epithelial barriers of the intestine. Significance and function in defense against infection].

The epithelial surface of the intestinal tract provides for an important barrier between the organism and its environment. However, it permits the passage into the tissues of limited amounts of macromolecules and/or particles, especially bacteria. These functions are age- and species-dependent, and they are closely related to nonspecific and specific immune reactions. Continuous and intimate contact between antigenic material from the gut lumen and immunocompetent cells takes place in gut-associated lymphoid tissues.

Bacterial Infections

Phytolacca acinosa Roxb. induces intestinal toxicity through the histamine-MLCK-tight junction axis: Integrated evidence from proteomics, metabolomics, intestinal organoids and epithelial barrier validation.

Phytolacca acinosa Roxb. (PR) is a saponin-rich medicinal plant associated with gastrointestinal toxicity, but the mechanisms underlying PR-induced intestinal barrier injury remain unclear. In this study, raw PR extract was analytically characterized by UPLC-ZenoTOF-MS/MS, confirming triterpenoid saponins as the predominant constituents. C57BL/6&#x202f;J mice were orally exposed to characterized PR extract (1.20 or 12.0&#x202f;g/kg for 5&#x202f;h), and Caco-2 cells and mouse intestinal organoids were used to assess epithelial toxicity and barrier disruption. Histopathology, ELISA, FITC-dextran permeability assays, immunofluorescence, CCK-8, LDH release, western blotting, DIA-based proteomics and untargeted metabolomics were integrated to define toxicological mechanisms. PR induced dose-dependent intestinal inflammation and barrier dysfunction, with the ileum as the most sensitive target. PR increased serum DAO and D-lactate and intestinal TNF-&#x3b1; and IL-1&#x3b2;, disrupted organoid morphology, enhanced epithelial permeability, and reduced ZO-1 expression. Proteomics revealed changes in inflammatory, lipid-metabolic, cytoskeletal and tight-junction pathways, including upregulation of MLCK3 and phospholipase-related proteins and downregulation of ZO-1 and ZO-2. Metabolomics identified histidine metabolism disturbance and histamine accumulation. Integrated multi-omics and pharmacological validation indicated that histamine activated the PLC/IP&#x2083;/Ca&#xb2;&#x207a;/CaM/MLCK cascade, promoting MLC phosphorylation, tight-junction disassembly and epithelial leakiness. MLCK inhibition partially restored ZO-1/ZO-2 expression and attenuated PR-induced epithelial injury. These findings identify the histamine-MLCK-tight junction axis as a key mechanism of PR-induced intestinal toxicity and support hazard identification of saponin-rich PR exposure.

Animals

A Review on Heat Stress in Broiler Chickens: Mechanisms, Effects and Mitigation Strategies.

BACKGROUND: Heat stress (HS) is a major environmental challenge for broilers, particularly under rising global temperatures and high humidity. Broiler chickens are highly susceptible because of their rapid growth rate, high metabolic heat production, limited thermoregulatory capacity and genetic selection for fast growth. OBJECTIVE: This review aims to synthesise current evidence, evaluate the effectiveness of existing mitigation strategies, identify key knowledge gaps and provide future research directions to improve broiler resilience, welfare and productivity under increasingly HS conditions. METHODS: This review synthesised evidence published between 2010 and 2025 on the physiological, metabolic, intestinal, immunological and productive consequences of HS and evaluated mitigation strategies. RESULTS: The reviewed studies demonstrate that HS reduces feed intake by approximately 10%-30%, suppresses body weight gain and feed efficiency and increases mortality, with severity depending on temperature, humidity and broiler genotype. HS disrupts carbohydrate, protein and lipid metabolism; induces acid-base imbalance and oxidative stress; compromises intestinal barrier integrity; alters gut microbiota; suppresses immune function; and reduces meat quality. Nutritional interventions, including dietary electrolyte balance, antioxidants, vitamins, selenium, zinc, phytogenic compounds, probiotics, betaine and optimised feeding strategies, environmental management and genetic approaches, including naked-neck and frizzle genes, can partially alleviate these adverse effects. However, inconsistencies among studies persist because of differences in broiler strains, environmental conditions, dietary formulations and experimental protocols. CONCLUSION: HS substantially compromises broiler health, welfare, productivity and meat quality. Nutritional, environmental and genetic approaches can partially mitigate its adverse effects; however, further research is needed to improve broiler resilience under increasingly HS conditions.

Animals