Intestinal epithelial organoids: regeneration and maintenance of the intestinal epithelium

The emerging role of intestinal stem cells in ulcerative colitis

Ulcerative colitis (UC) is a chronic idiopathic inflammatory disease affecting the colon and rectum. Characterized by recurrent attacks, UC is often resistant to traditional anti-inflammatory therapies, imposing significant physiological, psychological, and economic burdens on patients. In light of these challenges, innovative targeted therapies have become a new expectation for patients with UC. A crucial pathological feature of UC is the impairment of the intestinal mucosal barrier, which underlies aberrant immune responses and inflammation. Intestinal stem cells (ISCs), which differentiate into intestinal epithelial cells, play a central role in maintaining this barrier. Growing studies have proved that regulating the regeneration and differentiation of ISC is a promising approach to treating UC. Despite this progress, there is a dearth of comprehensive articles describing the role of ISCs in UC. This review focuses on the importance of ISCs in maintaining the intestinal mucosal barrier in UC and discusses the latest findings on ISC functions, markers, and their regulatory mechanisms. Key pathways involved in ISC regulation, including the Wnt, Notch, Hedgehog (HH), Hippo/Yap, and autophagy pathways, are explored in detail. Additionally, this review examines recent advances in ISC-targeted therapies for UC, such as natural or synthetic compounds, microbial preparations, traditional Chinese medicine (TCM) extracts and compounds, and transplantation therapy. This review aims to offer novel therapeutic insights and strategies for patients who have long struggled with UC.

Inhibition of the Wnt/β‑catenin signaling pathway and SOX9 by XAV939 did not alleviate inflammation in a dextran sulfate sodium‑induced ulcerative colitis model

The Wnt/β-catenin signaling pathway has been reported to be hyperactivated during the pathogenesis of ulcerative colitis (UC). The present study aimed to explore the therapeutic efficacy of the Wnt/β-catenin signaling inhibitor XAV939 in mitigating UC symptoms. Utilizing a dextran sulfate sodium (DSS)-induced UC mouse model, the present study aimed to evaluate the impact of XAV939 on intestinal morphology through hematoxylin and eosin staining and to measure the expression levels of critical proteins in the Wnt/β-catenin signaling cascade. XAV939 did not exert a significant influence on the morphological features and inflammatory status of the intestinal epithelium. However, XAV939 was found to effectively suppress the Wnt/β-catenin signaling pathway and its downstream target SOX9. This suppression implied a reduction in the differentiation of intestinal stem cells into secretory cell progenitor cells. Additionally, XAV939 was ineffective at reversing the DSS-induced decrease in expression levels of Villin and peroxisome proliferator-activated receptor γ, which suggested that it did not facilitate the differentiation of intestinal absorptive cells. The present findings indicated that the Wnt/β-catenin signaling pathway may not be the predominant mechanism in the pathogenesis of DSS-induced UC.

Toxicological assessments based on intestine 3D organoids reveal environmental low-dose nanosized microplastics (NPs) exposure aggravates radiation-induced intestine injury

BACKGROUND

Intestinal organoid has emerged as an energetic tool for modeling intestine physiology and relevant diseases in vitro. Here, we reported that development of intestinal organoids could be used to explore the toxicology mechanism for combination effects of low dose nanoplastic (NPs) chronic exposure and acute radiation on intestine injury, the two classical chemical and physical substances.

METHODS

Integrated acute radiation-induced intestine injury model in vivo and mice intestinal organoids in vitro were conducted in this study.

RESULTS

First, through in vivo study, we found low dose NPs exposure could aggravate acute radiation-induced intestine injury including exacerbating damaged intestinal epithelial structure, shortened and fractured intestinal villi. Second, using an intestinal organoid model, we observed that low-dose NPs reduced radiation-induced proliferation and exacerbated inflammatory damage, which promoted inflammatory damage through elevated TGF-β1 expression, increased Smad3 phosphorylation, and diminished Smad7 expression. Furthermore, immunohistochemical and Western blot analyses of intestinal tissues further confirmed that low-dose nanoplastics enhance radiation-induced intestinal damage via activation of the TGF-β1/p-Smad3 signaling pathway.

CONCLUSION

This study demonstrates that low-dose NPs may exacerbate the radiation-induced intestinal damage and inflammation process in vivo and in vitro. Our study highlights, for the first time, the potential for intestine organoids serving as powerful tool for explore the combination effects of two chemical and physical substances in toxicology investigation.

Cultivating complexity: Advancements in establishing in vitro models for the mucus-adhering gut microbiota

A healthy mucus is essential for maintaining intestinal homeostasis and overall well-being. In recent years, extensive research focused on understanding the intricate interactions between mucus and the gut microbiota. Mucus-adhering bacteria play crucial roles in preserving barrier integrity, epithelial permeability and mucus architecture, as well as in the colonization resistance against pathogens. Unravelling the significance of these microorganisms in human health and disease is challenging, primarily because most of the studies on the human gut microbiota rely on faecal samples, which do not fully represent the microecological complexity found in the intestinal mucosa. This review discusses novel strategies to specifically target and evaluate the mucosal microbiota, such as culturomics applied to mucosal biopsies or brushings, intestinal organoids and artificial in vitro models incorporating mucus.

10-Eicosanol Alleviates Patulin-Induced Cell Cycle Arrest and Apoptosis by Activating AKT (Protein Kinase B) in Porcine Intestinal Epithelial Cells

Patulin (PAT) is a fungal toxin prevalent in apples and apple products and associated with several toxic effects, potentially harming multiple organs, including the kidneys, liver, and colon. However, the precise molecular mechanism through which PAT affects the intestines remains comprehensively unclear. Therefore, this study aims to investigate the molecular effects of PAT on the intestinal epithelium. Gene expression profiling was conducted, hypothesizing that PAT induces cell cycle arrest and apoptosis through the PI3K-Akt signaling pathway. Cell cycle analysis, along with Annexin-V and propidium iodide staining, confirmed that PAT induced G2/M phase arrest and apoptosis in IPEC-J2 cells. Additionally, PAT activated the expression of cell cycle-related genes (CDK1, CCNB1) and apoptosis-related genes (BCL6, CASP9). Treatment with SC79, an AKT activator, mitigated cell cycle arrest and apoptosis. To identify natural products that could mitigate the harmful effects of PAT in small intestinal epithelial cells in pigs, the high-throughput screening of a natural product library was conducted, revealing 10-Eicosanol as a promising candidate. In conclusion, our study demonstrates that 10-Eicosanol alleviates PAT-induced cell cycle arrest and apoptosis in IPEC-J2 cells by activating AKT.

Non-TGFβ profibrotic signaling in ulcerative colitis after in vivo experimental intestinal injury in humans

Although impaired regeneration is important in many gastrointestinal diseases including ulcerative colitis (UC), the dynamics of mucosal regeneration in humans are poorly investigated. We have developed a model to study these processes in vivo in humans. Epithelial restitution (ER) and extracellular matrix (ECM) regulation after an experimental injury of the sigmoid colonic mucosa was assessed by repeated high-resolution endoscopic imaging, histological assessment, RNA sequencing, deconvolution analysis, and 16S rDNA sequencing of the injury niche microbiome of 19 patients with UC in remission and 20 control subjects. Human ER had a 48-h lag before induction of regenerative epithelial cells [wound-associated epithelial (WAE) and transit amplifying (TA) cells] along with the increase of fibroblast-derived stem cell growth factor gremlin 1 mRNA (GREM1). However, UC deconvolution data showed rapid induction of inflammatory fibroblasts and upregulation of major structural ECM collagen mRNAs along with tissue inhibitor of metalloproteinase 1 (TIMP1), suggesting increased profibrotic ECM deposition. No change was seen in transforming growth factor β (TGFβ) mRNA, whereas the profibrotic cytokines interleukin 13 (IL13) and IL11 were upregulated in UC, suggesting that human postinjury responses could be TGFβ-independent. In conclusion, we found distinct regulatory layers of regeneration in the normal human colon and a potential targetable profibrotic dysregulation in UC that could lead to long-term end-organ failure, i.e., intestinal damage.NEW & NOTEWORTHY The study reveals the regulatory dynamics of epithelial regeneration and extracellular matrix remodeling after experimental injury of the human colon in vivo and shows that human intestinal regeneration is different from data obtained from animals. A lag phase in epithelial restitution is associated with induction of stromal cell-derived epithelial growth factors. Postinjury regeneration is transforming growth factor β-independent, and we find a profibrotic response in patients with ulcerative colitis despite being in remission.

Organoids as regenerative medicine for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disorder with an increasing global prevalence. Managing disease activity relies on various pharmacological options. However, the effectiveness of current therapeutics is limited and not universally applicable to all patients and circumstances. Consequently, developing new management strategies is necessary. Recent advances in endoscopically obtained intestinal biopsy specimens have highlighted the potential of intestinal epithelial organoid transplantation as a novel therapeutic approach. Experimental studies using murine and human organoid transplantations have shown promising outcomes, including tissue regeneration and functional recovery. Human trials with organoid therapy have commenced; thus, this article provides readers with insights into the necessity and potential of intestinal organoid transplantation as a new regenerative therapeutic option in clinical settings and explores its associated challenges.

Protective effect of zinc gluconate on intestinal mucosal barrier injury in antibiotics and LPS-induced mice

Objective

The aim of the study is to investigate the function and mechanism of Zinc Gluconate (ZG) on intestinal mucosal barrier damage in antibiotics and Lipopolysaccharide (LPS)-induced mice.

Methods

We established a composite mouse model by inducing intestinal mucosal barrier damage using antibiotics and LPS. The animals were divided into five groups: Control (normal and model) and experimental (low, medium, and high-dose ZG treatments). We evaluated the intestinal mucosal barrier using various methods, including monitoring body weight and fecal changes, assessing pathological damage and ultrastructure of the mouse ileum, analyzing expression levels of tight junction (TJ)-related proteins and genes, confirming the TLR4/NF-κB signaling pathway, and examining the structure of the intestinal flora.

Results

In mice, the dual induction of antibiotics and LPS led to weight loss, fecal abnormalities, disruption of ileocecal mucosal structure, increased intestinal barrier permeability, and disorganization of the microbiota structure. ZG restored body weight, alleviated diarrheal symptoms and pathological damage, and maintained the structural integrity of intestinal epithelial cells (IECs). Additionally, ZG reduced intestinal mucosal permeability by upregulating TJ-associated proteins (ZO-1, Occludin, Claudin-1, and JAM-A) and downregulating MLCK, thereby repairing intestinal mucosal barrier damage induced by dual induction of antibiotics and LPS. Moreover, ZG suppressed the TLR4/NF-κB signaling pathway, demonstrating anti-inflammatory properties and preserving barrier integrity. Furthermore, ZG restored gut microbiota diversity and richness, evidenced by increased Shannon and Observed features indices, and decreased Simpson's index. ZG also modulated the relative abundance of beneficial human gut bacteria (Bacteroidetes, Firmicutes, Verrucomicrobia, Parabacteroides, Lactobacillus, and Akkermansia) and harmful bacteria (Proteobacteria and Enterobacter), repairing the damage induced by dual administration of antibiotics and LPS.

Conclusion

ZG attenuates the dual induction of antibiotics and LPS-induced intestinal barrier damage and also protects the intestinal barrier function in mice.

Intestinal Mucosal Immune Barrier: A Powerful Firewall Against Severe Acute Pancreatitis-Associated Acute Lung Injury via the Gut-Lung Axis

The pathogenesis of severe acute pancreatitis-associated acute lung injury (SAP-ALI), which is the leading cause of mortality among hospitalized patients in the intensive care unit, remains incompletely elucidated. The intestinal mucosal immune barrier is a crucial component of the intestinal epithelial barrier, and its aberrant activation contributes to the induction of sustained pro-inflammatory immune responses, paradoxical intercellular communication, and bacterial translocation. In this review, we firstly provide a comprehensive overview of the composition of the intestinal mucosal immune barrier and its pivotal roles in the pathogenesis of SAP-ALI. Secondly, the mechanisms of its crosstalk with gut microbiota, which is called gut-lung axis, and its effect on SAP-ALI were summarized. Finally, a number of drugs that could enhance the intestinal mucosal immune barrier and exhibit potential anti-SAP-ALI activities were presented, including probiotics, glutamine, enteral nutrition, and traditional Chinese medicine (TCM). The aim is to offer a theoretical framework based on the perspective of the intestinal mucosal immune barrier to protect against SAP-ALI.

A Strainer-Based Platform for the Collection and Immunolabeling of Porcine Epidemic Diarrhea Virus-Infected Porcine Intestinal Organoid

The development of organoid research has raised new requirements for this methodology. In a previous study, we demonstrated that an emerging protocol achieved the collection, loading, and programmed immunolabeling of mouse intestinal organoids based on a strainer platform. To uncover the applied potential of this novel methodology on organoids from other species, the strainer platform was utilized to characterize the porcine epidemic diarrhea virus (PEDV)-infected porcine intestinal organoid model. Based on a previous study, some steps were changed to improve the efficiency of the assay by simplifying the reagent addition procedure. In addition, we redefined the range of strainer sizes on porcine intestinal organoids, showing that strainers with pore sizes of 40 and 70 μm matched the above protocol well. Notably, the strainer platform was successfully used to label viral proteins, laying the foundation for its application in the visualization of viral infection models. In summary, the potential of the strainer platform for organoid technology was explored further. More extensive exploration of this platform will contribute to the development of organoid technology.

Stem cell-derived intestinal organoids: a novel modality for IBD

The organoids represent one of the greatest revolutions in the biomedical field in the past decade. This three-dimensional (3D) micro-organ cultured in vitro has a structure highly similar to that of the tissue and organ. Using the regeneration ability of stem cells, a 3D organ-like structure called intestinal organoids is established, which can mimic the characteristics of real intestinal organs, including morphology, function, and personalized response to specific stimuli. Here, we discuss current stem cell-based organ-like 3D intestinal models, including understanding the molecular pathophysiology, high-throughput screening drugs, drug efficacy testing, toxicological evaluation, and organ-based regeneration of inflammatory bowel disease (IBD). We summarize the advances and limitations of the state-of-the-art reconstruction platforms for intestinal organoids. The challenges, advantages, and prospects of intestinal organs as an in vitro model system for precision medicine are also discussed. Key applications of stem cell-derived intestinal organoids. Intestinal organoids can be used to model infectious diseases, develop new treatments, drug screens, precision medicine, and regenerative medicine.

The protective role of Lactobacillus rhamnosus GG postbiotic on the alteration of autophagy and inflammation pathways induced by gliadin in intestinal models

Celiac disease (CD) is an autoimmune enteropathy caused by an abnormal immune response to gliadin peptides in genetically predisposed individuals. For people with CD, the only available therapy thus far is the lifelong necessity for a gluten-free diet (GFD). Innovative therapies include probiotics and postbiotics as dietary supplements, both of which may benefit the host. Therefore, the present study aimed to investigate the possible beneficial effects of the postbiotic Lactobacillus rhamnosus GG (LGG) in preventing the effects induced by indigested gliadin peptides on the intestinal epithelium. In this study, these effects on the mTOR pathway, autophagic function, and inflammation have been evaluated. Furthermore, in this study, we stimulated the Caco-2 cells with the undigested gliadin peptide (P31-43) and with the crude gliadin peptic-tryptic peptides (PTG) and pretreated the samples with LGG postbiotics (ATCC 53103) (1 × 108). In this study, the effects induced by gliadin before and after pretreatment have also been investigated. The phosphorylation levels of mTOR, p70S6K, and p4EBP-1 were increased after treatment with PTG and P31-43, indicating that the intestinal epithelial cells responded to the gliadin peptides by activating the mTOR pathway. Moreover, in this study, an increase in the phosphorylation of NF-κβ was observed. Pretreatment with LGG postbiotic prevented both the activation of the mTOR pathway and the NF-κβ phosphorylation. In addition, P31-43 reduced LC3II staining, and the postbiotic treatment was able to prevent this reduction. Subsequently, to evaluate the inflammation in a more complex intestinal model, the intestinal organoids derived from celiac disease patient biopsies (GCD-CD) and controls (CTR) were cultured. Stimulation with peptide 31-43 in the CD intestinal organoids induced NF-κβ activation, and pretreatment with LGG postbiotic could prevent it. These data showed that the LGG postbiotic can prevent the P31-43-mediated increase in inflammation in both Caco-2 cells and in intestinal organoids derived from CD patients.