Search Results (386)

Salmonella infects a wide range of hosts, causing gastroenteritis or systemic infection in humans and animals, highlighting the urgent need for a deeper understanding of its pathogenesis. SpvC, a critical virulence determinant of salmonella, facilitates bacterial dissemination. Gasdermin D (GSDMD) is the only gasdermin known to protect mice against acute Salmonella enteritis. Our preliminary findings indicated that SpvC counteracts GSDMD-mediated antibacterial effects to enhance bacterial dissemination, although its functional relevance to epithelial-derived GSDMD and the underlying mechanisms remain unclear. To address this, Gsdmd^−/− C57BL/6J and wild-type mice were infected with Salmonella Typhimurium (S. Typhimurium) wild-type strain and spvC deletion mutant. Our results demonstrate that SpvC compromises intestinal epithelial barrier integrity, overcoming GSDMD-mediated protection against systemic infection. Specifically, through bioinformatics analysis, LC-MS/MS, and in vivo experiments with Caco-2 cell monolayers and site-directed spvC mutants, we identified SEC23B as a novel target of SpvC. This interaction disrupts the intestinal epithelial barrier through the autophagy–pyroptosis pathway. This study identifies SEC23B as a unique cellular target of SpvC involved in GSDMD activation during S. Typhimurium systemic infection. It also reveals a novel mechanism by which Salmonella evades host defense mechanisms. Full article

Inflammatory bowel diseases (IBDs) are diseases of chronic inflammation and intestinal epithelial cell (IEC) death that affect an estimated 7 million people worldwide. Intestinal barrier restoration is the most important determinant of remission in IBD, yet there are very few existing therapies that protect IECs from damage or support epithelial repair. The goal of this study was to develop a model system and tools that can be used to identify therapeutics that promote IEC survival in IBD. We developed a Beclin-1 cleavage reporter (BICR) that detects calpain-mediated Beclin-1 cleavage and the switch from autophagy to programmed cell death. We modified BICR with the HIV Tat peptide (BICR-Tat) and tested it in a model of live bacterial stress using commensal E. coli and IEC. BICR sensitively and specifically detected calpain activity in cell-free assays, and BICR-Tat successfully detected Beclin-1 cleavage and autophagy failure in IEC. Achieving IEC survival in the microbe-challenged IBD gut would be an important advance toward intestinal barrier restoration in this intractable disease. The BICR-Tat reporter coupled with the model of microbial stress developed in this study could enable high-throughput screening approaches to identify therapeutics with the potential to achieve barrier healing and sustained remission in IBD. Full article

This study investigated whether the therapeutic efficacy of Chinese yam polysaccharide (CYP) against ulcerative colitis (UC) depends on an intact gut microbiota. A dextran sulfate sodium (DSS)-induced colitis mouse model was established, and one treatment group received broad-spectrum antibiotics (ABXs) before CYP administration to deplete the intestinal microbiota. CYP markedly attenuated colonic injury, reduced disease activity, and suppressed inflammatory mediators under both microbiota-intact and microbiota-depleted conditions. CYP also enhanced intestinal barrier integrity, as evidenced by reduced serum endotoxin levels and increased expression of MUC-2, Claudin-1, Occludin, and ZO-1. In addition, CYP improved hepatic antioxidant status by increasing GSH-Px and catalase activities and decreasing malondialdehyde levels. Moreover, CYP reduced the activation of the NF-κB and MAPK signaling pathways, with similar trends observed under microbiota-depleted conditions. Microbiota profiling showed that CYP partially corrected DSS-induced dysbiosis, whereas the ABX + CYP group exhibited distinct microbial patterns with enrichment of carbohydrate-related metabolic pathways predicted by PICRUSt2. Collectively, these findings suggest that CYP retains protective efficacy after antibiotic pretreatment, indicating that its effects may not be exclusively dependent on gut microbiota modulation, possibly involving direct actions on immune and intestinal epithelial cells. Full article

Porcine β-defensin 2 (pBD2) possesses broad-spectrum antimicrobial properties and is crucial for gastrointestinal mucosal repair. Lactic acid bacteria (LAB) serve as optimal vectors for exogenous protein delivery due to their high biosafety, intestinal colonization capacity, and ability to modulate gut microecology. In this study, we engineered a recombinant Lactobacillus paracasei strain (pPG-N1-pBD2/27-2) that efficiently secretes pBD2. In vitro, this recombinant strain significantly enhanced the proliferation and migration of porcine intestinal epithelial cells (IPEC-J2). In vivo, oral administration of pPG-N1-pBD2/27-2 markedly alleviated dextran sulfate sodium (DSS)-induced colitis in mice. This protective effect was evidenced by reduced Disease Activity Index (DAI) scores, prevention of colon shortening, and decreased colonic activities of myeloperoxidase (MPO) and eosinophil peroxidase (EPO), alongside normalized N-acetyl-β-D-glucosaminidase (NAG) levels. Histopathological analysis revealed that the treatment preserved mucosal architecture, including goblet cells and crypts, and fortified the physical barrier by upregulating tight junction proteins. Mechanistically, the recombinant strain suppressed the colonic iNOS/COX-2 inflammatory axis, decreased serum pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α), and elevated the anti-inflammatory cytokine IL-10. Furthermore, it restored systemic immune homeostasis by normalizing the proportions of splenic macrophages, T/B lymphocytes, and natural killer (NK) cells. In conclusion, pPG-N1-pBD2/27-2 mitigates colitis through a dual mechanism: reinforcing the intestinal physical barrier and rebalancing the innate–adaptive immune axis. These findings highlight the potential of pBD2-engineered probiotics as novel biological therapeutics for intestinal inflammatory diseases. Full article

Background: Vancomycin (VAN)-induced nephrotoxicity limits its clinical application. Licorice (Glycyrrhiza uralensis Fisch.) and its bioactive constituents have been reported to protect against nephrotoxicity induced by various nephrotoxic agents. This study aimed to evaluate the protective effects of licorice against VAN-induced nephrotoxicity and to explore the underlying mechanisms both in vivo and in vitro. Methods: Seven groups of male C57BL/6 mice received different treatments for 7 consecutive days. Blood, fecal and renal tissue samples were collected for the assessment of serum creatinine, renal histopathology, mitochondrial ultrastructure, oxidative stress markers, kidney injury molecule-1 (Kim-1), short-chain fatty acids (SCFAs), and uremic toxins. In human proximal tubular epithelial cells (HK-2 cells), the effects of licorice on cell viability, oxidative stress, inflammatory markers, and mitochondrial membrane potential (MMP) were further investigated. Results: Licorice significantly attenuated VAN-induced nephrotoxicity and restored glutathione peroxidase (GSH-Px) activity while reducing malondialdehyde (MDA) levels. In addition, licorice markedly ameliorated VAN-induced renal histopathological injury, as demonstrated by hematoxylin and eosin staining and transmission electron microscopy. Licorice also reversed VAN-induced intestinal microbiota dysbiosis and increased the relative abundance of SCFA-producing bacteria, including Bacteroides. Moreover, licorice treatment increased fecal SCFA contents and modulated multiple uremic toxins in both serum and renal tissue. Consistently, licorice protected HK-2 cells against VAN-induced cytotoxicity by regulating GSH, interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and MMP. Conclusions: These findings demonstrate that licorice exerts protective effects against VAN-induced nephrotoxicity in vivo and in vitro, suggesting the potential involvement of oxidative stress, mitochondrial structure and function, inflammation, intestinal microbiota-SCFAs and uremic toxins. Full article

Purpose: Inflammatory bowel disease (IBD) is a chronic inflammatory disorder strongly associated with intestinal microbial dysregulation. Although 5-aminosalicylic acid (5-ASA) is widely used in the clinical management of IBD, its therapeutic efficacy is often limited. To address this, the present study aimed to develop a bifidobacterium-derived extracellular vesicle-based drug delivery system (B-MVs@5-ASA) to enhance the therapeutic outcomes of IBD. Methods: B-MVs were isolated by PEG precipitation and loaded with 5-ASA via sonication to obtain B-MVs@5-ASA. Their morphology, particle size, zeta potential, and encapsulation efficiency were analyzed using TEM, DLS, and UV spectrophotometry. Cellular uptake, cytotoxicity (LDH and NO assays), and anti-inflammatory effects were assessed in RAW 264.7 and Caco-2 cells. A DSS-induced colitis mouse model was established to evaluate therapeutic efficacy. Cytokines (ELISA), colon histopathology (H&E), tight-junction proteins (IF), and gut microbiota composition (16S rRNA sequencing) were systematically analyzed. Results: B-MVs@5-ASA exhibited a particle size of 104.3 ± 2.81 nm and an encapsulation efficiency of 11.14% ± 3.63%. B-MVs@5-ASA exhibited the strongest anti-inflammatory effect in vitro and most effectively alleviated DSS-induced colitis in vivo, outperforming monotherapies in reducing inflammation, tissue damage, and enhancing barrier integrity. B-MVs@5-ASA further promoted goblet cell regeneration and beneficially modulated the gut microbiota by enriching Akkermansia and suppressing Escherichia, thereby restoring microbial homeostasis. Conclusions: B-MVs@5-ASA provides potent anti-inflammatory and mucosal-protective effects by modulating cytokine balance, enhancing epithelial barrier function, and reshaping gut microbiota. These findings highlight probiotic vesicle-based nanoplatforms as a safe and promising strategy for targeted IBD therapy. Full article

Dysregulation of the immune system, gut microbiota alteration, and epithelial dynamics in the colon contribute to the pathogenesis of inflammatory bowel disease (IBD). However, the role of epithelial dynamics, particularly epithelial regeneration, remains incompletely understood. CADM1 encodes an immunoglobulin-superfamily cell adhesion molecule involved in epithelial adhesion, immune cell interactions, and tumor suppression in colon and various cancers. Here, we investigated the role of CADM1 in IBD using a murine model of colitis induced by dextran sulfate sodium in both wild-type and conventional Cadm1-deficient (Cadm1^−/−) mice. Cadm1^−/− mice exhibited more severe colitis than wild-type mice with increased mortality (64% vs. 10%) and delayed recovery. Cadm1^−/− mice showed reduced numbers of Ki-67-positive cells in colonic crypts and delayed epithelial regeneration, whereas no significant differences were observed in epithelial apoptosis, intestinal permeability, or immune responses. Immunohistochemistry revealed that CADM1 expression was restricted to regenerative crypt cells in wild-type mice with nuclear accumulation of β-catenin and phospho-Akt. Furthermore, CADM1 overexpression in colon epithelial cells enhanced Tcf-transcriptional activity in a β-catenin-dependent manner. Immunohistochemistry of human IBD materials revealed that CADM1 expression also correlated with nuclear β-catenin accumulation in crypt epithelial cells. Collectively, CADM1 appears to promote colonic epithelial regeneration through the PI3K/Akt/β-catenin axis to protect against severe epithelial injury in IBD. Full article

Chemotherapy-induced mucositis (CIM) is a dose-limiting toxicity of cancer therapy that is mainly associated with mitochondrial dysfunction in epithelial cells. We investigated whether GV1001, a mitochondrial protective peptide from human telomerase reverse transcriptase (hTERT), attenuates 5-fluorouracil (5-FU)-induced mucositis in a murine model. 5-FU induced notable mortality, leukopenia, and mucositis in the gastrointestinal (GI) tract, including tongue, esophagus and small intestine. It promoted epithelial–mesenchymal transition (EMT), nuclear factor kappa-B (NF-κB) activation, systemic and mucosal inflammation, DNA damage, impaired cell proliferation, and apoptosis throughout the GI tract. GV1001 blocked 5-FU–associated mortality, significantly attenuated leukopenia, and notably prevented mucositis. GV1001 also suppressed 5-FU-induced DNA damage, EMT, loss of proliferative capacity, apoptosis, and NF-κB activation in mucosal epithelium. In normal human keratinocytes, 5-FU inhibited the cell proliferation, disrupted mitochondrial function, as evidenced by reduced mitochondrial membrane potential, increased reactive oxygen species (ROS) production, impaired electron transport chain (ETC) complex integrity, decreased ATP synthesis, and cytochrome c release into the cytosol. GV1001 markedly mitigated these 5-FU-induced mitochondrial defects. Taken together, GV1001 mitigates CIM by most likely preserving mitochondrial integrity and function, supporting its potential as a strategy to prevent cancer chemotherapy-associated mucosal injury in patients. Full article

Our previous work demonstrated that bovine milk-derived extracellular vesicles (mEVs) could alleviate the inflammatory response of mice colitis, along with hundreds of differentially expressed (DE) mRNAs. This study further analyzed the profiles of non-coding RNAs (ncRNAs) and explored the correlation with DE mRNAs by constructing ceRNA networks. Six-week-old male C57BL/6 mice were fed either a control diet or a diet added with mEVs for 30 days. Then the mice were given dextran sulphate sodium in drinking water for 7 days to induce colitis. A total of 40 miRNAs, 541 lncRNAs and 643 circRNAs exhibited changes in mEVs pretreatment group. Among these DE miRNAs, mEVs pretreatment significantly increased the expressions of miR-122, miR-147, miR-210, miR-1224, miR-148a, and miR-212, which might participate in the inflammatory response of the colitis models. The expression of Tug1 increased after mEVs pretreatment, while Snhg5 and H19 decreased, which might be involved in intestinal barrier restoration. Functional analysis of the DE ncRNAs suggested mEVs might exert protective effects not only through modulation of inflammatory responses but also by enhancing intestinal stem cell function and epithelial regeneration, which were mainly regulated by Wnt and Hippo signaling pathways according to the ceRNA networks. Full article

Three new, previously undescribed tanzawaic acids, steckwaic acids H–J (1–3), and twenty-three known natural products (4–26) were isolated from the marine algicolous fungus Penicillium steckii SCSIO 41040. Structurally, compound 3 underwent a rare hydration reaction at the double bond of its carboxylic acid side chain. The chemical structures and stereochemistry were determined using comprehensive spectroscopic analyses, including NMR, electronic circular dichroism (ECD) calculations, and high-resolution electrospray ionization mass spectrometry (HRESIMS), and verified by literature comparison. The protective effect of tanzawaic acids on inflammatory damage to the intestinal epithelial barrier was assessed using an LPS-stimulated Caco-2/THP-1 co-culture model. Notably, immunofluorescence and Western blotting assays showed that compound 10 significantly enhanced the fluorescence signals and protein expression of ZO-1 and occludin, alleviated lipopolysaccharide (LPS)-induced intestinal barrier damage in Caco-2 cells, and contributed to the re-establishment of intestinal barrier homeostasis. Our findings demonstrate the critical role of tanzawaic acids in maintaining intestinal barrier integrity, identifying them as promising lead compounds for UC treatment. Full article

Trained immunity is a concept that is currently in development and refers to the long-term functional reprogramming of innate immune cells in response to microbial or inflammatory stimuli. This process serves a dual purpose in the gastrointestinal tract, contributing to chronic inflammatory conditions like inflammatory bowel disease and maintaining host defense. The production of pro-inflammatory mediators is augmented by epigenetic and metabolic changes that are induced by the persistent activation of innate immune cells, which is triggered by microbial components and damage-associated signals. Although this increased responsiveness may initially be protective, sustained activation leads to tissue damage, epithelial barrier dysfunction, and chronic inflammation. These mechanisms are significant contributors to colorectal carcinogenesis, particularly in colitis-associated cancer. Through the activation of oncogenic signaling pathways, the establishment of a pro-tumorigenic microenvironment, and an increase in oxidative stress, trained immunity also influences tumor development. Additionally, the systemic reprogramming of hematopoietic progenitor cells has the potential to exacerbate inflammation and facilitate the progression of tumors. The identification of epigenetic and metabolic biomarkers associated with trained immunity can lead to novel diagnostic opportunities. Targeting metabolic and epigenetic pathways, as well as regulating the intestinal microbiota, is a promising therapeutic approach that could enhance the effectiveness of treatments for colorectal cancer while minimizing adverse effects on the immune system. Nevertheless, it is necessary to maintain a delicate equilibrium to suppress pathological inflammation without compromising protective immune responses. In general, trained immunity may represent a potentially relevant mechanistic link between chronic inflammation and colorectal cancer; however, its role remains context-dependent and not yet fully defined. Full article

Respiratory infections remain a leading cause of morbidity and mortality worldwide, highlighting the urgent need to better understand host defense mechanisms in the respiratory tract. Recent advances in sequencing technologies have challenged the traditional view of the lungs as sterile organs and revealed the presence of a distinct, low-biomass microbial community known as the lung microbiota. These microbial populations interact closely with airway epithelial cells and immune cells to maintain respiratory homeostasis and regulate host immune responses. In healthy lungs, microbial communities dominated by Firmicutes, Bacteroidetes, and Proteobacteria contribute to immune regulation through interactions with innate and adaptive immune pathways. Microbiota-derived signals are detected by pattern recognition receptors, activating signaling pathways that regulate cytokine production, immune cell recruitment, and T-cell differentiation. In the respiratory mucosa, microbial stimulation can also induce epithelial and antigen-presenting cells to produce B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL), which promote immunoglobulin A (IgA) class-switch recombination and support mucosal antibody responses. During pulmonary infection, disruption of microbial communities can lead to dysbiosis that amplifies inflammatory responses, impairs epithelial barrier integrity, and increases susceptibility to secondary bacterial infections. In addition to local microbial interactions, the gut–lung axis represents a key communication pathway linking intestinal microbiota with respiratory immunity through microbial metabolites such as short-chain fatty acids (SCFAs) and immune signaling networks. This review summarizes current insights into microbiota–immune crosstalk in the lung during pulmonary infection and discusses how these interactions may inform mucosal vaccine development. A deeper understanding of host–microbiota interactions may enable microbiome-informed vaccines and therapeutic strategies to improve protection against respiratory diseases. Full article

Liquid infant formula has garnered increasing attention due to its mild thermal processing and superior retention of bioactive nutrients. Within such matrices, the lipid source is a critical determinant of protein digestion behavior, yet its influence on peptide bioavailability and intestinal homeostasis remains undefined. Given that efficient peptide absorption is vital for the systemic delivery of bioactivity in infants, understanding the lipid–protein synergy is essential for formula optimization. Moreover, excessive oxidative stress is closely associated with impaired intestinal health and developmental disorders in infants, making the regulation of oxidative stress crucial for maintaining intestinal function. The present study evaluated the effects of three distinct lipid sources—soybean oil (SM), bovine milk fat (BM), and goat milk fat (GM)—on the physicochemical stability, proteolytic digestion, peptide release, intestinal absorption, and oxidative stress modulation of goat-milk-based infant formula. An integrated approach combining physicochemical characterization, in vitro simulated infant digestion, and a Caco-2 intestinal epithelial cell model was employed. we demonstrate that all three lipids (3% w/w) formed stable emulsions with uniform spherical structures and mean particle diameters of 117–300 nm, as visualized by laser confocal microscopy. Following in vitro simulation of infant gastrointestinal digestion, the SM group exhibited the most extensive protein hydrolysis, yielding the highest total peptide content (4.28 ± 0.10 mg/mL) and generated the highest number of peptides identified by LC-MS/MS (474 types). Bioinformatic analysis predicted that peptides from all groups possess potential antihypertensive, hypoglycemic, and immunomodulatory activities. The Caco-2 monolayer cell model demonstrated that although the GM group produced fewer identified peptide species than the SM group (365 types), it achieved significantly higher intestinal peptide absorption rate (55.34 ± 1.05%). Furthermore, the GM digests provided superior protection against H₂O₂-induced oxidative stress in Caco-2 cells, markedly reducing reactive oxygen species levels and suppressing the expression of pro-inflammatory cytokines TNF-α and IL-6. Collectively, these findings reveal that while soybean oil promotes more extensive proteolysis, the use of homologous goat milk lipid enhances peptide bioaccessibility and confers potential cytoprotective effects on intestinal epithelial cells, underscoring its potential as a preferred lipid source in infant formula formulations. Full article

The intestinal epithelial barrier regulates paracellular transport, and its dysfunction is associated with inflammatory and metabolic diseases. Among dietary fibers, inulin has attracted considerable attention due to its beneficial effects on intestinal health. Inulin’s actions have been attributed to protecting the structure and function of gut barrier components against inflammatory-associated damage. This review integrates preclinical and clinical studies evaluating the impact of inulin on intestinal permeability. Evidence from in vitro and in vivo models shows that inulin regulates the expression of tight junction proteins (TJPs), Paneth cell proliferation, and antimicrobial peptides, and modulates inflammatory signaling pathways. In addition, inulin prebiotic activity, via microbiota, stimulates the production of short-chain fatty acids (SCFAs) as butyrate that reinforces the barrier function. Understanding these pathways highlights the therapeutic potential of inulin as a nutritional strategy for treating barrier dysfunction. Clinical studies in obesity, metabolic disorders and inflammatory intestinal disease have associated inulin supplementation with improvements in biomarkers of intestinal permeability. Future studies are needed to test inulin’s safety in order to prevent potential risks and hazards. Full article

Oxidative stress in intestinal epithelial cells has been increasingly recognized as a key factor in various intestinal disorders. Gastrodia elata polysaccharide-2 (GEP-2), a water-soluble polysaccharide known for its antioxidant properties, has shown potential against intestinal injury. However, its effects on intestinal epithelial cells and the molecular mechanisms involved are not yet fully understood. In this study, we established a hydrogen peroxide (H₂O₂)-induced oxidative stress model using human colonic epithelial cells (NCM460) to evaluate the protective effects of GEP-2. We assessed cell viability, antioxidant enzyme activities, reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP). The results demonstrated that GEP-2 pretreatment significantly improved the viability of NCM460 cells subjected to H₂O₂ damage. Additionally, it could enhance the antioxidant defense, reduce the levels of ROS, malondialdehyde (MDA), and maintain the MMP. Transcriptomic analysis identified 169 differentially expressed genes upregulated in the glutathione metabolism. JAK-STAT pathway and downregulated in inflammation. Furthermore, it was shown that GEP-2 treatment activated the Nuclear factor erythroid 2-related factor 2 (Nrf2)/quinone oxidoreductase 1 (NQO1)-mediated antioxidant response and promoted the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway. Therefore, GEP-2 exerts multi-targeted cell protection by coordinating the Nrf2/NQO1 antioxidant axis and the JAK/STAT survival signaling pathway, providing a theoretical basis for the development of novel antioxidants. Full article