Adult intestinal stem cells: Critical drivers of epithelial homeostasis and regeneration. Nat Rev Mol Cell Biol. 2014;15:19-33. [PMID: 24326621 DOI: 10.1038/nrm3721]

New insights in amino sugar metabolism by the gut microbiome

Gut microorganisms inhabiting the intestinal tract play key roles in host's health and disease. A properly functioning gut microbiome requires the availability of adequate carbon, nitrogen and energy sources. One of the main sources of energy for intestinal bacteria are glycans, of which amino sugars are important components. Amino sugars are a class of carbohydrates in which one or more hydroxyl groups are substituted with amino groups. However, bacterial utilization of amino sugars and their impact on the gut microbiome and host health have not been thoroughly assessed. In this review, we summarize the latest discoveries about amino sugar metabolism by gut microbes, paying particular attention to the metabolism of N-acetyl-galactosamine (GalNAc), one of the most abundant amino sugars in the intestine, and its potential implications for microbial functionality and host health.

The gut-skin axis: a bi-directional, microbiota-driven relationship with therapeutic potential

This review explores the emerging term "gut-skin axis" (GSA), describing the bidirectional signaling that occurs between the skin and the gastrointestinal tract under both homeostatic and disease conditions. Central to GSA communication are the gut and skin microbiota, the microbial communities that colonize these barrier surfaces. By influencing diverse host pathways, including innate immune, vitamin D receptor, and Aryl hydrocarbon receptor signaling, a balanced microbiota contributes to both tissue homeostasis and host defense. In contrast, microbiota imbalance, or dysbiosis at one site, can lead to local barrier dysfunction, resulting in the activation of signaling pathways that can disrupt tissue homeostasis at the other site, potentially leading to inflammatory skin conditions such as atopic dermatitis and psoriasis, or gut diseases like Inflammatory Bowel Disease. To date, most research on the GSA has examined the impact of the gut microbiota and diet on skin health, but recent studies show that exposing the skin to ultraviolet B-light can beneficially modulate both the gut microbiome and intestinal health. Thus, despite the traditional focus of clinicians and researchers on these organ systems as distinct, the GSA offers new opportunities to better understand the pathogenesis of cutaneous and gastrointestinal diseases and promote health at both sites.

Modulation of intestinal signal transduction pathways: Implications on gut health and disease

The gastrointestinal (GI) tract is essential for nutrient absorption and protection against pathogens and toxins. Its epithelial lining undergoes continuous renewal every 3-5 days, driven by intestinal stem cells (ISCs). ISCs are primarily of two types: actively proliferating crypt base columnar cells (CBCs), marked by Lgr5 expression, and quiescent label-retaining cells (+4 LRCs), which act as reserves during stress or injury. Key signaling pathways, such as Wnt/β-catenin, Notch, bone morphogenetic proteins (BMPs), and epidermal growth factor (EGF), are crucial in maintaining epithelial homeostasis. These pathways regulate ISCs proliferation and their differentiation into specialized epithelial cells, including goblet cells, paneth cells, enteroendocrine cells, and enterocytes. Disruptions in ISCs signaling can arise from extrinsic factors (e.g., dietary additives, heavy metals, pathogens) or intrinsic factors (e.g., genetic mutations, metabolic changes). Such disruptions impair tight junction integrity, induce inflammation, and promote gut dysbiosis, often perpetuating a cycle of intestinal dysfunction. Chronic ISCs dysregulation is linked to severe intestinal disorders, including colorectal cancer (CRC) and inflammatory bowel disease (IBD). This review emphasizes the critical role of ISCs in maintaining epithelial renewal and how various factors disrupt their signaling pathways, jeopardizing intestinal health and contributing to diseases. It also underscores the importance of protecting ISCs function to mitigate the risk of inflammation-related disorders. It highlights how understanding these regulatory mechanisms could guide therapeutic strategies for preserving GI tract integrity and treating related conditions.

Pdia3 deficiency exacerbates intestinal injury by disrupting goblet and Paneth cell function during ischemia/reperfusion

Intestinal ischemia/reperfusion (I/R) injury is a severe medical condition associated with high mortality rates due to its disruption of intestinal homeostasis and impairment of mucosal defenses. The intestinal epithelium, particularly goblet and Paneth cells, plays a critical role in maintaining gut barrier integrity. Protein disulfide isomerase A3 (PDIA3) is involved in protein folding within intestinal epithelial cells (IECs) and has been linked to the stress response during I/R injury. This study aims to explore the role of PDIA3 in preserving intestinal integrity and immune function during I/R injury. Our study employed both human and mouse models to investigate PDIA3's expression and function. The correlation between PDIA3 expression and disease severity was analyzed using statistical tests, including Pearson's correlation coefficient. An intestinal I/R model was established in intestinal epithelium-specific conditional knockout mice lacking the Pdia3 gene. Single-cell RNA sequencing, immunohistochemistry, and transcriptomic analysis were used to assess PDIA3 expression in various intestinal cell types and to evaluate its role in epithelial differentiation and immune responses. PDIA3 was found to be highly expressed in healthy IECs, especially in goblet and Paneth cells. Its expression was reduced in patients with mesenteric artery ischemia and Pdia3-deficient mice, leading to severe intestinal damage, including impaired goblet and Paneth cell function, reduced antimicrobial peptide production, and altered gut microbiota. Treatment with recombinant defensin α1, an antimicrobial peptide secreted by Paneth cells, significantly alleviated the adverse effects of Pdia3 deficiency, restoring gut microbiota balance and reducing inflammation in the intestinal I/R injury mice. Taken together, our findings suggest that Pdia3 plays a vital role in maintaining intestinal barrier function and immune defense. Its deficiency exacerbates I/R-induced intestinal damage by impairing epithelial differentiation, mucus production, and antimicrobial peptide secretion. Targeting Pdia3 and associated pathways offers promising therapeutic strategies for mitigating I/R injury and restoring intestinal homeostasis.

Experimental toolkit to study the oncogenic role of WNT signaling in colorectal cancer

Colorectal cancer (CRC) is linked to the WNT/β-catenin signaling as its primary driver. Aberrant activation of WNT/β-catenin signaling is closely correlated with increased incidence, malignancy, poorer prognosis, and even higher cancer-related death. Research over the years has postulated various experimental models that have facilitated an understanding of the complex mechanisms underlying WNT signaling in CRC. In the present review, we have comprehensively summarized the in vitro, in vivo, patient-derived, and computational models used to study the role of WNT signaling in CRC. We discuss the use of CRC cell lines and organoids in capturing the molecular intricacies of WNT signaling and implementing xenograft and genetically engineered mouse models to mimic the tumor microenvironment. Patient-derived models, including xenografts and organoids, provide valuable insights into personalized medicine approaches. Additionally, we elaborated on the role of computational models in simulating WNT signaling dynamics and predicting therapeutic outcomes. By evaluating the advantages and limitations of each model, this review highlights the critical contributions of these systems to our understanding of WNT signaling in CRC. We emphasize the need to integrate diverse model systems to enhance translational research and clinical applications, which is the primary goal of this review.

Intestinal epithelial cells in health and disease

This comprehensive review delves into the pivotal role of intestinal epithelial cells in the context of various diseases. It provides an in-depth analysis of the diverse types and functions of these cells, explores the influence of multiple signaling pathways on their differentiation, and elucidates their critical roles in a spectrum of diseases. The significance of the gastrointestinal tract in maintaining overall health is extremely important and cannot be exaggerated. This complex and elongated organ acts as a crucial link between the internal and external environments, making it vulnerable to various harmful influences. Preserving the normal structure and function of the gut is essential for well-being. Intestinal epithelial cells serve as the primary defense mechanism within the gastrointestinal tract and play a crucial role in preventing harmful substances from infiltrating the body. As the main components of the digestive system, they not only participate in the absorption and secretion of nutrients and the maintenance of barrier function but also play a pivotal role in immune defense. Therefore, the health of intestinal epithelial cells is of vital importance for overall health.

Chlorpyrifos Inhibits Intestinal Stem Cell Proliferation and Differentiation at the Acceptable Daily Intake and Disrupts Immune Responses at High Doses

The acceptable daily intake (ADI) and maximum residue limits in food for chlorpyrifos (CPF), a widely used organophosphorus pesticide, may damage the intestine. Here, we evaluated damage to the intestine by CPF at the ADI (0.01 mg/kg bodyweight/day) and at 10 times the ADI (10ADI; 0.1 mg/kg bodyweight/day) in mice after 8 weeks of exposure and evaluated the resulting immune response to an enterotoxigenic Escherichia coli (ETEC) infection. CPF at the ADI dose significantly disrupted the intestinal integrity and intestinal stem cell functionality, which may be associated with reduced indole-3-propionic acid levels. However, mice in the 10ADI group exhibited only elevated pro-inflammatory cell and cytokine levels. During ETEC infection, intestinal mucosal immunity was activated by the 10ADI dose, as indicated by increased regulatory T cells and IL-10 levels, which were associated with decreased fecal butyric acid content. Our study demonstrated that the effects of pesticide residues appear to be dose-specific, bringing attention to the health risk at the ADI level.

Bixin alleviates radiation-induced intestinal damage via inflammation regulation and barrier recovery

PURPOSE

Radiotherapy for cancer treatment or unintentional exposure to ionizing radiation causes severe damage to the unaffected tissues of the digestive system, including gastrointestinal (GI) tract. Radiation exposure leads to an inflammatory response, and uncontrolled inflammation exacerbates radiation-induced tissue injury. Bixin is a liposoluble apocarotenoid isolated from Bixa orrellana seeds, which effectively attenuates several inflammatory diseases. In this study, we investigated whether bixin mitigated radiation-induced intestinal damage through an examination of its role in inflammation and the protection of the epithelial barrier.

MATERIALS AND METHODS

To determine the therapeutic effects of bixin in treating radiation-induced intestinal damage, we carried out histological analyses, inflammatory response examinations, and barrier function assessments using a mouse model of radiation-induced enteropathy.

RESULTS

We uncovered that bixin effectively mitigates radiation-induced enteropathy by suppressing the inflammatory response, reducing inflammatory cell accumulation, and limiting cytokine expression in the radiation-induced intestinal injury. In a mouse model of acute radiation-induced intestinal injury, treatment with bixin enhanced nuclear factor erythroid-2-related factor 2 (NRF2) activation and promoted tight junction expression in the epithelium, while also hindering bacterial translocation to the mesenteric lymph nodes.

CONCLUSION

Bixin represents a potential therapeutic candidate for the treatment of radiation-induced enteropathy.

The signature of the small intestinal epithelial and immune cells in health and diseases

ABSTRACT

The small intestine is essential for digestion, nutrient absorption, immune regulation, and microbial balance. Its epithelial lining, containing specialized cells like Paneth and tuft cells, is crucial for maintaining intestinal homeostasis. Paneth cells produce antimicrobial peptides and growth factors that support microbial regulation and intestinal stem cells, while tuft cells act as chemosensors, detecting environmental changes and modulating immune responses. Along with immune cells such as intraepithelial lymphocytes, innate lymphoid cells, T cells, and macrophages, they form a strong defense system that protects the epithelial barrier. Disruptions in this balance contribute to chronic inflammation, microbial dysbiosis, and compromised barrier function-key features of inflammatory bowel disease, celiac disease, and metabolic syndromes. Furthermore, dysfunctions in the small intestine and immune cells are linked to systemic diseases like obesity, diabetes, and autoimmune disorders. Recent research highlights promising therapeutic strategies, including modulation of epithelial and immune cell functions, probiotics, and gene editing to restore gut health and address systemic effects. This review emphasizes the pivotal roles of small intestinal epithelia and immune cells in maintaining intestinal homeostasis, their involvement in disease development, and emerging treatments for intestinal and systemic disorders.

Bacillus subtilis Fed to Sows Promotes Intestinal Development and Regulates Mucosal Immunity in Offspring

Diarrhea in piglets causes intestinal inflammation and epithelial damage. Weaned piglets fed with Bacillus subtilis (B.S) have enhanced intestinal mucosal immunity and reduces diarrhea in piglets. However, the immune system of newborn piglets is immature, and B.S cannot effectively activate the intestinal mucosal reaction when given directly. This research explored the impact of the maternal supplementation of B.S-Dia during the final 35 days of gestation on piglet intestinal development and mucosal immunity. The results demonstrated that B.S-Dia administration significantly increased the body weight, jejunal villus height, and crypt depth in the piglets. In addition, B.S-Dia also significantly increased the proliferative activity of intestinal epithelial cells, as evidenced by proliferating cell nuclear antigen (PCNA) staining and the elevated mRNA expression of the proliferation-related gene (c-Myc). Furthermore, B.S-Dia supplementation also reinforced the intestinal mucosal barrier by increasing goblet cell numbers and upregulating the mRNA expression of antimicrobial peptides, such as Muc2 and Lyz-1. Finally, elevated levels of IL-4 and IFN-γ, along with an increased abundance of CD3+ T cells, revealed that the intestinal mucosal immunity of piglets was improved after B.S-Dia administration. Our study indicates that feeding B.S-Dia to sow spromotes intestinal development and improves intestinal mucosal immunity in piglets.

Engineering the Future of Regenerative Medicines in Gut Health with Stem Cell-Derived Intestinal Organoids

The advent of intestinal organoids, three-dimensional structures derived from stem cells, has significantly advanced the field of biology by providing robust in vitro models that closely mimic the architecture and functionality of the human intestine. These organoids, generated from induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), or adult stem cells, possess remarkable capabilities for self-renewal, differentiation into diverse intestinal cell types, and functional recapitulation of physiological processes, including nutrient absorption, epithelial barrier integrity, and host-microbe interactions. The utility of intestinal organoids has been extensively demonstrated in disease modeling, drug screening, and personalized medicine. Notable examples include iPSC-derived organoids, which have been effectively employed to model enteric infections, and ESC-derived organoids, which have provided critical insights into fetal intestinal development. Patient-derived organoids have emerged as powerful tools for investigating personalized therapeutics and regenerative interventions for conditions such as inflammatory bowel disease (IBD), cystic fibrosis, and colorectal cancer. Preclinical studies involving transplantation of human intestinal organoids into murine models have shown promising outcomes, including functional integration, epithelial restoration, and immune system interactions. Despite these advancements, several challenges persist, particularly in achieving reproducibility, scalability, and maturation of organoids, which hinder their widespread clinical translation. Addressing these limitations requires the establishment of standardized protocols for organoid generation, culture, storage, and analysis to ensure reproducibility and comparability of findings across studies. Nevertheless, intestinal organoids hold immense promise for transforming our understanding of gastrointestinal pathophysiology, enhancing drug development pipelines, and advancing personalized medicine. By bridging the gap between preclinical research and clinical applications, these organoids represent a paradigm shift in the exploration of novel therapeutic strategies and the investigation of gut-associated diseases.

Titanium dioxide nanoparticles disturb glucose homeostasis in association with impaired enteroendocrine cell differentiation

Gut hormones secreted by enteroendocrine cells play a critical role in maintaining glucose homeostasis. However, the adverse endocrine effects related to glucose homeostasis caused by food additives are not well understood. This work aims to investigate the effects of titanium dioxide nanoparticles (TiO2 NPs) in comparison to titanium dioxide microparticles (TiO2 MPs) on glucose homeostasis, with a specific focus on the enteroendocrine cells and gut hormones. Our research found that exposure to 1 % (w/w) TiO2 NPs, unlike TiO2 MPs, resulted in elevated blood glucose levels and impaired glucose tolerance in mice. Notably, 1 % (w/w) TiO2 NPs significantly influenced the differentiation of the intestinal epithelium while not causing any notable histological changes or affecting cell proliferation in the mouse ileum. Furthermore, the levels of gut hormones, including glucagon-like peptide-1 (GLP-1), peptide YY (PYY) and cholecystokinin (CCK), released from mouse ileum tissues were also significantly reduced following exposure to 1 % (w/w) TiO2 NPs. Using the intestinal organoid model, we also discovered that 20 μg/mL TiO2 NPs impaired enteroendocrine cell differentiation, reduced basal GLP-1 secretion levels, and disrupted the GLP-1 secretion response to nutrient stimuli. Our research highlights the detrimental effects of TiO2 NPs as potential intestinal endocrine disruptor and underscores the need to optimize their particle size for safe use in the food industry.

Effects of 1,3-Dioleoyl-2-palmitoylglycerol on Intestine Structural and Functional Development in Early Life

1,3-Dioleoyl-2-palmitoyl-glycerol (OPO) is a specific triglyceride in human breast milk, and it has been added to infant formula to mimic human breast milk fat. Existing studies only focused on its effects on fatty acid and calcium absorption, as well as the intestinal microbial composition; however, effects of OPO on the early-life development of intestine were still unclear. Our study explored the effects of OPO on intestinal epithelial structure and barrier construction in neonatal mice and the involvement of intestinal microorganisms. OPO supplementation significantly increased the number of intestinal stem cells, which in turn promoted villus and crypt, and promoted goblet cell and Paneth cell differentiation. OPO also promotes epithelial barrier integrity by increasing the expression of mucin 2, lysozyme 1, and tight junction proteins. Furthermore, the benefits of OPO were associated with the higher abundance of beneficial bacteria (unclassified_f_Muribaculaceae, Akkermansia, Bifidobacterium, and Blautia) and elevated butyrate levels. This study demonstrates the efficacy of OPO on intestinal health in neonatal mice beyond defecation, expands the understanding of the biological functions of OPO, and expands its application in intestinal health products targeting special populations, such as the elderly or individuals with intestinal fragility or injury.

Vagal pathway activation links chronic stress to decline in intestinal stem cell function

Chronic stress adversely affects intestinal health, but the specific neural pathways linking the brain to intestinal tissue are not fully understood. Here, we show that chronic stress-induced activation of the central amygdala-dorsal motor nucleus of the vagus (CeA-DMV) pathway accelerates premature aging and impairs the stemness of intestinal stem cells (ISCs). This pathway influences ISC function independently of the microbiota, the hypothalamic-pituitary-adrenal (HPA) axis, the immune response, and the sympathetic nervous system (SNS). Under chronic stress, DMV-mediated vagal activation prompts cholinergic enteric neurons to release acetylcholine (ACh), which engages ISCs via the M3 muscarinic acetylcholine receptor (CHRM3). This interaction activates the p38 mitogen-activated protein kinase (MAPK) pathway, triggering growth arrest and mitochondrial fragmentation, thereby accelerating an aging-like decline in ISCs. Together, our findings provide insights into an alternative neural mechanism that links stress to intestinal dysfunction. Strategies targeting the DMV-associated vagal pathway represent potential therapeutic approaches for stress-induced intestinal diseases.

Therapeutic activation of IL-22-producing innate lymphoid cells enhances host defenses to Clostridioides difficile infection

Clostridioides difficile causes debilitating colitis via secreted toxins that disrupt the intestinal barrier, and toxemia is associated with severe disease. Thus, therapies that fortify the intestinal barrier will reduce the severity of infection. Innate lymphoid cells (ILCs) are critical in the defense against acute C. difficile infection and represent a promising therapeutic target to limit disease. Here, we report that oral administration of the Toll-like receptor (TLR) 7 agonist R848 limits intestinal damage and protects mice from lethal C. difficile infection without impacting pathogen burden or altering the intestinal microbiome. R848 induced interleukin (IL)-22 secretion by ILCs, leading to STAT3 phosphorylation in the intestinal epithelium and increased stem cell proliferation. Genetic ablation of ILCs, IL-22, or epithelial-specific STAT3 abrogated R848-mediated protection. R848 reduced intestinal permeability following infection and limited systemic toxin dissemination. Combined, these data identify an immunostimulatory molecule that activates IL-22 production in ILCs to enhance host tissue defenses following C. difficile infection.

Bacteroides fragilis 839 ameliorates anti-tuberculosis drugs-induced liver injury by suppressing inflammation and regulating gut microbiota in mice

Anti-tuberculosis drug-induced liver injury (ATB-DILI), caused by first-line anti-tuberculosis (anti-TB) drugs, disrupts treatment and increases the risk of drug resistance. The gut microbiota and intestinal barrier integrity play key roles in ATB-DILI susceptibility through the liver-gut axis. Probiotics, such as Bacteroides fragilis 839 (BF839), have shown therapeutic potential in modulating gut microbiota and inflammatory responses. In this study, we investigated the protective effects of BF839 on ATB-DILI in a mouse model of HRZE-induced liver injury. BF839 administration significantly alleviated HRZE-induced liver injury by reducing ALT, AST, AKP, and MDA levels, enhancing SOD and GSH levels, and improving liver histopathology. These effects were associated with restored gut microbiota diversity, enhanced intestinal barrier function, and reduced inflammatory responses. Our findings suggest that BF839 may serve as a potential preventive strategy for ATB-DILI.

Abortive PDCoV infection triggers Wnt/β-catenin pathway activation, enhancing intestinal stem cell self-renewal and promoting chicken resistance

Porcine deltacoronavirus (PDCoV) is an emerging coronavirus causing economic losses to swine industries worldwide. PDCoV can infect chickens under laboratory conditions, usually with no symptoms or mild symptoms, and may cause outbreaks in backyard poultry and wildfowl, posing a potential risk of significant economic loss to the commercial poultry industry. However, the reasons for such a subdued reaction after infection are not known. Here, using chicken intestinal organoid monolayers, we found that although PDCoV infects them nearly as well as porcine intestinal organoid monolayers, infection did not result in detectable amounts of progeny virus. In ex vivo and in vivo experiments using chickens, PDCoV infection failed to initiate interferon and inflammatory responses. Additionally, infection did not result in a disrupted intestinal barrier nor a reduced number of goblet cells and mucus secretion, as in pigs. In fact, the number of goblet cells increased as did the secreted mucus, thereby providing an enhanced protective barrier. Ex vivo PDCoV infection in chicken triggered activation of the Wnt/β-catenin pathway with the upregulation of Wnt/β-catenin pathway genes (Wnt3a, Lrp5, β-catenin, and TCF4) and Wnt target genes (Lgr5, cyclin D1, and C-myc). This activation stimulates the self-renewal of intestinal stem cells (ISCs), accelerating ISC-mediated epithelial regeneration by significant up-regulation of PCNA (transiently amplifying cells), BMI1 (ISCs), and Lyz (Paneth cells). Our data demonstrate that abortive infection of PDCoV in chicken cells activates the Wnt/β-catenin pathway, which facilitates the self-renewal and proliferation of ISCs, contributing to chickens' resistance to PDCoV infection.IMPORTANCEThe intestinal epithelium is the main target of PDCoV infection and serves as a physical barrier against pathogens. Additionally, ISCs are charged with tissue repair after injury, and promoting rapid self-renewal of intestinal epithelium will help to re-establish the physical barrier and maintain intestinal health. We found that PDCoV infection in chicken intestinal organoid monolayers resulted in abortive infection and failed to produce infectious virions, disrupt the intestinal barrier, reduce the number of goblet cells and mucus secretion, and induce innate immunity, but rather increased goblet cell numbers and mucus secretion. Abortive PDCoV infection activated the Wnt/β-catenin pathway, enhancing ISC renewal and accelerating the renewal and replenishment of shed PDCoV-infected intestinal epithelial cells, thereby enhancing chicken resistance to PDCoV infection. This study provides novel insights into the mechanisms underlying the mild or asymptomatic response to PDCoV infection in chickens, which is critical for understanding the virus's potential risks to the poultry industry.

Inflamed Intestinal Epithelial Cells From Patients With Ulcerative Colitis Restore a Noninflamed Transcriptional Profile Upon In Vitro Expansion

Ulcerative colitis (UC) is characterized by chronic relapsing inflammation starting from the rectum and distal colon, which in severe disease cases may affect the entire colon. Intestinal stem cells (ISCs) directly isolated from inflamed UC colonic tissue specimens have been found to present an inflammatory gene expression profile. However, a critical issue is whether these cells retain memory of exposure to inflammation and/or therapeutics. Here, we aimed to investigate whether human intestinal epithelial cells retain the inflammatory state observed in vivo when expanded in vitro as 3D cultured organoids to assess their suitability for therapeutic transplantation. ISCs were isolated from noninflammatory bowel disease controls (noninflamed; n = 18), as well as from colonoscopy-obtained biopsies of the sigmoid colon from individuals diagnosed with UC (inflamed), who were glucocorticoid naïve (n = 19). Moreover, ISCs were collected from all patients with inflammatory bowel disease following prednisolone treatment. Epithelial cells were cultured as 3D intestinal organoids in media to support stem cell maintenance and differentiation. Subsequently, the 3D intestinal organoids were harvested at the end of passage 2 for bulk RNA sequencing. The data revealed that the cellular phenotype of in vitro-cultured epithelial cells isolated from inflamed tissue did not maintain the hallmarks of inflammation observed in the ulcerated environment from which the cells were initially obtained. Our findings indicate that the autologous reinsertion of in vitro-expanded ISCs in active stages of UC may aid in intestinal healing, which calls for future clinical studies. Additionally, a link between organoid morphology and the inflammatory state of the tissue of origin was identified, as organoids derived from inflamed colon exhibited a lower degree of circularity.

Colonic epithelial-derived FGF1 drives intestinal stem cell commitment toward goblet cells to suppress inflammatory bowel disease

Understanding the molecular mechanisms that regulate intestinal epithelial cell (IEC) renewal provides potential targets for inflammatory bowel disease (IBD). Growing evidence has highlighted the importance of epithelial signals in regulating intestinal stem cell (ISC) differentiation. However, it remains unclear which IEC-derived cytokines can precisely regulate ISC commitment toward specific mature cells. Here we systematically analyze all fibroblast growth factors (FGFs) expression and find that colonic FGF1 levels are inversely correlated with the severity of IBD in mouse models and patients. IEC-specific Fgf1 deletion leads to impaired goblet cell differentiation and exacerbated colitis, while pharmacological administration of recombinant FGF1 (rFGF1) alleviates colitis by enhancing goblet cell differentiation and improving colonic epithelial integrity. Mechanistic studies reveal that rFGF1 directs ISC differentiation toward goblet cells via FGFR2-TCF4-ATOH1 signaling axis. In conclusion, our study identifies an epithelial niche-derived FGF1 that regulates ISC commitment toward goblet cells, shedding light on strategies for treating IBD.

Cell origin and microenvironment: The players of differentiation capacity in human mesenchymal stem cells

Mesenchymal stem cells (MSCs) have several important properties that make them desirable for regenerative medicine. These properties include immunomodulatory ability, growth factor production, and differentiation into various cell types. Despite extensive research and promising results in clinical trials, our understanding of MSC biology, their mechanism of action, and their targeted and routine use in clinics is limited. Differentiation of human MSCs (hMSCs) is a complex process influenced by various elements such as growth factors, pharmaceutical compounds, microRNAs, 3D scaffolds, and mechanical and electrical stimulation. Research has shown that different culture conditions can affect the differentiation potential of hMSCs obtained from multiple fetal and adult sources. Additionally, it seems that what affects the differentiation capacities of these cells is their secretory characteristics, which are influenced by the origin of the cells and the local microenvironment where the cells are located. The review can provide insights into the microenvironment-based mechanisms involved in MSC differentiation, which can be valuable for future therapeutic applications.

Role of the Aryl Hydrocarbon Receptor in the Self-Renewal, Differentiation, and Immunomodulation of Adult Stem Cells

Adult stem cells are a rare population of undifferentiated cells present in almost all body tissues. Depending on their location, stem cells can differentiate into various tissue types, primarily contributing to maintenance, repair, and immune system regulation. Stem cell therapies have significant potential in regenerative medicine and treatment of inflammatory diseases. However, many factors must be considered for successful clinical commercialization, including enhancing therapeutic potential, ensuring product differentiation, and optimizing the manufacturing process for large-scale production. The development of sophisticated regulatory mechanisms may enhance therapeutic applications. The aryl hydrocarbon receptor (AhR) is expressed in all adult stem cells, and its activation and function are tightly regulated. Understanding the role and regulation of AhR is crucial for developing effective stem cell therapies. This review examines the role of the AhR in regulating the fundamental characteristics of adult stem cells, which may contribute to advancing adult stem cell therapies.

Advances and applications of gut organoids: modeling intestinal diseases and therapeutic development

Gut organoids are 3D cellular structures derived from adult or pluripotent stem cells, capable of closely replicating the physiological properties of the gut. These organoids serve as powerful tools for studying gut development and modeling the pathogenesis of intestinal diseases. This review provides an in-depth exploration of technological advancements and applications of gut organoids, with a focus on their construction methods. Additionally, the potential applications of gut organoids in disease modeling, microenvironmental simulation, and personalized medicine are summarized. This review aims to offer perspectives and directions for understanding the mechanisms of intestinal health and disease as well as for developing innovative therapeutic strategies.

Mitochondrial damage-associated molecular patterns: New perspectives for mitochondria and inflammatory bowel diseases

Mitochondria are key regulators of inflammatory responses and mitochondrial dysfunction is closely linked to various inflammatory diseases. Increasing genetic and experimental evidence suggests that mitochondria play a critical role in inflammatory bowel disease (IBD). In the complex environment of the intestinal tract, intestinal epithelial cells (IECs) and their mitochondria possess unique phenotypic features, shaping each other and regulating intestinal homeostasis and inflammation through diverse mechanisms. Here, we focus on intestinal inflammation in IBD induced by mitochondrial damage-associated molecular patterns (mtDAMPs), which comprise mitochondrial components and metabolic products. The pathogenic mechanisms of mtDAMP signaling pathways mediated by two major mtDAMPs, mitochondrial DNA (mtDNA) and mitochondrial reactive oxygen species (mtROS), are discussed.

Stem Cell Markers LGR5, LGR4 and Their Immediate Signalling Partners are Dysregulated in Preeclampsia

Leucine-rich repeat-containing G protein-coupled receptors 5/4 (LGR5/LGR4) are critical stem cell markers in epithelial tissues including intestine. They agonise wingless-related integration site (WNT) signalling. Until now, LGR5/LGR4 were uncharacterised in placenta, where analogous functions may exist. We characterised LGR5/LGR4, their ligands/targets in human placenta, with further assessments on dysregulation in preeclampsia/fetal growth restriction (FGR). LGR5 mRNA was unaltered in first trimester (n = 11), preterm (n = 9) and term (n = 11) placental lysate. LGR5 was enriched in human trophoblast stem cells (hTSCs) and downregulated with differentiation to extravillous trophoblasts (p < 0.0215) and syncytiotrophoblasts (p < 0.0350). In situ hybridisation localised LGR5 to unique, proliferative MKI67 + mononuclear trophoblasts underlying syncytium which concurred with proposed progenitor identities in single-cell transcriptomics. LGR5 expression was significantly reduced in placentas from early-onset preeclampsia (p < 0.0001, n = 81 versus n = 19 controls), late-onset preeclampsia (p = 0.0046, n = 20 versus n = 33 controls) and FGR (p = 0.0031, n = 34 versus n = 17 controls). LGR4 was elevated in first trimester versus preterm and term placentas (p = 0.0412), in placentas with early-onset preeclampsia (p = 0.0148) and in FGR (p = 0.0417). Transcriptomic analysis and in vitro hTSC differentiation to both trophoblast lineages suggested LGR4 increases with differentiation. Single-nucleus RNA sequencing of placental villous samples supported LGR5 and LGR4 localisation findings. Hypoxia/proinflammatory cytokine treatment modelling elements experienced by the placenta in placental insufficiency pathogenesis did not significantly alter LGR5/LGR4. Ligands R-spondins 1/3/4, and neutralising targets ring finger protein 43 (RNF43) and zinc and ring finger 3 (ZNRF3) were also reduced in placentas from preeclamptic pregnancies. This study is the first to describe LGR5/LGR4 and their signalling partner expression in human placenta. Their dysregulations in the preeclamptic placenta allude to disruptions to integral trophoblast stem cell function/differentiation that may occur during placental development related to WNT signalling.

Tuft cells transdifferentiate to neural-like progenitor cells in the progression of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is partly initiated through the transdifferentiation of acinar cells to metaplasia, which progresses to neoplasia and cancer. Tuft cells (TCs) are chemosensory cells not found in the normal pancreas but arise in cancer precursor lesions and diminish during progression to carcinoma. These metaplastic TCs (mTCs) suppress tumor progression through communication with the tumor microenvironment, but their fate during progression is unknown. To determine the fate of mTCs during PDA progression, we created a dual recombinase lineage trace model, wherein a pancreas-specific FlpO was used to induce tumorigenesis, while a tuft-cell specific Pou2f3CreERT/+ driver was used to induce expression of a tdTomato reporter. We found that mTCs in carcinoma transdifferentiate into neural-like progenitor cells (NRPs), a cell type associated with poor survival in patients. Using conditional knockout and overexpression systems, we found that Myc activity in mTCs is necessary and sufficient to induce this tuft-to-neuroendocrine transition (TNT).

Human Milk Oligosaccharide LNnT Promotes Intestinal Epithelial Growth and Maturation During the Early Life of Infant Mice

Lacto-N-neotetraose (LNnT) is a prevalent neutral core human milk oligosaccharides (HMOs) recognized for its numerous benefits to infant health. In infant formula, galactooligosaccharide (GOS) are frequently used as substitutes for HMOs. However, the regulatory roles of LNnT and GOS in early intestinal development are not yet fully understood. This study aims to elucidate the effects of LNnT and GOS on intestinal development during early life. Our findings show that administering LNnT or GOS significantly increased the spleen and liver indices of infant mice at postnatal day 21. Immunofluorescence and qPCR analysis showed that feeding LNnT significantly promoted the proliferation and differentiation of intestinal stem cells (ISCs) in the colon of infant mice at postnatal day 21, and increased the expression of differentiation markers of goblet cells, intestinal epithelial cells, Paneth cells, and intestinal endocrine cells. Conversely, feeding GOS had no significant effect on the proliferation and differentiation of ISCs. Furthermore, intestinal microbiota analysis showed that LNnT increased the microbiota associated with intestinal regeneration and ISCs proliferation and differentiation in infant mice at postnatal day 21. In conclusion, LNnT promoted ISCs proliferation and differentiation in the colon and alters the composition and function of the intestinal microbiota to support intestinal development in infant mice.

Digital PCR characterizes epithelial cell populations in murine duodenal organoids

Three-dimensional cultures are powerful tools to recapitulate animal and human tissues. Under the influence of specific growth factors, adult stem cells differentiate and organize into 3D cultures named organoids. The molecular phenotyping of these structures is an essential step for validating an organoid model. However, the limited number of organoids generated in culture yields very low amounts of genetic material, making phenotyping difficult. Recently, digital PCR (dPCR) techniques have become available for the highly sensitive detection of genetic material at low concentrations. The aim of this work was to apply dPCR to the identification of the various cell populations expected to be present in murine duodenal organoids. Results show the potential use of dPCR as a genetic characterization tool for organoids.

Intestinal Foxl1+ cell-derived CXCL12 maintains epithelial homeostasis by modulating cellular metabolism

Several mesenchymal cell populations are known to regulate intestinal stem cell (ISC) self-renewal and differentiation. However, the influences of signaling mediators derived from mesenchymal cells other than ISC niche factors on epithelial homeostasis remain poorly understood. Here, we show that host and microbial metabolites, such as taurine and gamma-aminobutyric acid (GABA), act on PDGFRαhigh Foxl1high sub-epithelial mesenchymal cells to regulate their transcription. In addition, we found that CXC chemokine ligand 12 (CXCL12) produced from Foxl1high sub-epithelial mesenchymal cells induces epithelial cell cycle arrest through modulation of the mevalonate-cholesterol synthesis pathway, which suppresses tumor progression in ApcMin/+ mice. We identified that Foxl1high sub-epithelial cells highly express CXCL12 among colonic mesenchymal cells. Foxl1-cre; Cxcl12f/f mice showed an increased number of Ki67+ colonic epithelial cells. CXCL12-induced Ca2+ mobilization facilitated phosphorylation of AMPK in intestinal epithelial cells, which inhibits the maturation of sterol regulatory element-binding proteins (SREBPs) that are responsible for mevalonate pathway activation. Furthermore, Cxcl12 deficiency in Foxl1-expressing cells promoted tumor development in the small and large intestines of ApcMin/+ mice. Collectively, these results demonstrate that CXCL12 secreted from Foxl1high mesenchymal cells manipulates intestinal epithelial cell metabolism, which links to the prevention of tumor progression in ApcMin/+ mice.

PRMT5 Maintains Homeostasis of the Intestinal Epithelium by Modulating Cell Proliferation and Survival

Intestinal homeostasis is sustained by self-renewal of intestinal stem cells, which continuously divide and produce proliferative transit-amplifying (TA) and progenitor cells. Protein arginine methyltransferases 5 (PRMT5) plays a crucial role in regulating homeostasis of various mammalian tissues. However, its function in intestinal homeostasis remains elusive. In this study, conditional knockout of Prmt5 in the mouse intestinal epithelium leads to a reduction in stem cell population, suppression of cell proliferation, and increased cell apoptosis within the intestinal crypts, accompanied with shortened gut length, decreased mouse body weight, and eventual animal mortality. Additionally, Prmt5 deletion or its enzymatic inhibition in intestinal organoids in vitro also shows resembling cellular phenotypes. Methylome profiling identifies 90 potential Prmt5 substrates, which are involved in RNA-related biological processes and cell division. Consistently, Prmt5 depletion in intestinal organoids leads to aberrant alternative splicing in a subset of genes related to the mitotic cell cycle. Furthermore, Prmt5 loss triggers p53-mediated apoptosis in the intestinal epithelium. Collectively, the findings uncover an indispensable role of PRMT5 in promoting cell proliferation and survival, as well as maintaining stem cells in the gut epithelium.

Dual independent mechanisms underlying gut epithelial remodeling upon sugar substitute consumption

Intestinal epithelial cells (IECs) are dynamically regulated by luminal contents, including dietary ingredients, food additives, and microbiota-derived metabolites. Although sugar substitutes are commonly used as food additives for their sweet taste and lower calorie content, there is limited experimental evidence regarding their potential to drive gut remodeling. In this study, we designed experimental models for short-term consumption of erythritol, a natural sugar alcohol widely used as a sugar substitute, and investigated its effects on gut remodeling and the underlying mechanisms. Our findings indicate that erythritol consumption induces hyperplasia in tuft cells (TCs) and goblet cells (GCs), as well as enhances the activity of intestinal stem cells-increases in expression levels of leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5), the key intestinal stem cell marker, in the number of proliferating stem cells, and facilitation of their differentiation into villi cells-while maintaining the number of Lgr5+ intestinal stem cells. Notably, the enhanced stem cell activity was observed even in Trpm5 knockout mice, suggesting that it is mechanistically independent of TC hyperplasia. Instead, we demonstrated the functional involvement of the gut microbiota, as antibiotic treatment abolished this effect, and fecal material transfer from erythritol-consumed mice replicated the enhancement of stem cell activity in recipient mice. Furthermore, we identified acetate as the metabolite responsible for enhancing stem cell activity. These findings suggest the functional decoupling of TC hyperplasia and the enhancement of stem cell activity, providing a potential therapeutic avenue for gut epithelial diseases.

Organoid-based in vitro system and reporter for the study of Cryptosporidium parvum sexual reproduction

Many advances have been made recently in our understanding of Cryptosporidium's asexual cycle and sexual differentiation. However, the process of fertilization, which is required for transmission of infectious oocysts, is not well understood. Typical cancer cell-based culture only allows robust exploration of asexual cycle and sexual differentiation of Cryptosporidium. To facilitate exploration of sexual reproduction in C. parvum we developed an organoid-based culture system that supports Cryptosporidium's full life cycle and a novel fertilization reporter. Organoid derived monolayers (ODMs) supported fertilization and oocyst production and maintained the infection for up to 3 weeks. ODM derived oocysts were infectious in vivo. Fertilization was confirmed by successfully mating two strains of C. parvum and with a novel fertilization switch reporter. The fertilization switch reporter utilizes a DiCre system in which cre fragments are expressed under the control of sexual stage promoters resulting in a rapamycin-inducible switch in fluorescent protein expression from mCherry to mNeonGreen after fertilization that is spatially and temporally controlled. This results in mCherry positive parasites in the first generation and offspring that express mNeonGreen. In vivo validation of the fertilization switch reporter demonstrated the precision and efficiency of the fertilization switch reporter and confirmed excision of the mCherry gene sequence only after rapamycin treatment. The start of a second generation of parasites was also shown in the ODMs and rarely in HCT8s. Use of this reporter in ODMs can help investigate the Cryptosporidium lifecycle post sexual differentiation in a physiologically relevant in vitro system.

H3K36 methylation regulates cell plasticity and regeneration in the intestinal epithelium

Plasticity is needed during development and homeostasis to generate diverse cell types from stem and progenitor cells. Following differentiation, plasticity must be restricted in specialized cells to maintain tissue integrity and function. For this reason, specialized cell identity is stable under homeostatic conditions; however, cells in some tissues regain plasticity during injury-induced regeneration. While precise gene expression controls these processes, the regulatory mechanisms that restrict or promote cell plasticity are poorly understood. Here we use the mouse small intestine as a model system to study cell plasticity. We find that H3K36 methylation reinforces expression of cell-type-associated genes to maintain specialized cell identity in intestinal epithelial cells. Depleting H3K36 methylation disrupts lineage commitment and activates regenerative gene expression. Correspondingly, we observe rapid and reversible remodelling of H3K36 methylation following injury-induced regeneration. These data suggest a fundamental role for H3K36 methylation in reinforcing specialized lineages and regulating cell plasticity and regeneration.

Organismal mucosal immunology: A perspective through the eyes of game theory

In complex organisms, functional units must interact cohesively to maintain homeostasis, especially within mucosal barriers that house diverse, specialized cell exposed to constant environmental challenges. Understanding how homeostasis at mucosal barriers is maintained and how its disruption can lead to autoimmune diseases or cancer, requires a holistic view. Although omics approaches and systems immunology have become powerful tools, they are not without limitations; interpretations may reflect researchers' assumptions, even if other explanations exist. In this perspective, I propose that applying game theory concepts to mucosal immunology could help interpret complex data, offering fresh perspectives and supporting the exploration of alternative scenarios. By framing the mucosal immune system as a network of strategic interactions with multiple possible outcomes, game theory, which analyzes strategic interactions and decision-making processes, could illuminate novel cell types and functions, cell interactions, and responses to pathogens and commensals, leading to a more comprehensive understanding of immune homeostasis and diseases. In addition, game theory might encourage researchers to consider a broader range of possibilities, reduce the risk of myopic thinking, and ultimately enable a more refined and comprehensive understanding of the complexity of the immune system at mucosal barriers. This perspective aims to introduce game theory as a complementary framework for mucosal immunologists, encouraging them to incorporate these concepts into data interpretation and system modeling.

Yeast cell wall polysaccharides accelerate yet in-feed antibiotic delays intestinal development and maturation via modulating gut microbiome in chickens

BACKGROUND

It is important to promote intestinal development and maturation of chicks for feed digestion and utilization, intestinal health, and disease resistance. This study aimed to investigate the effects of dietary yeast cell wall polysaccharides (YCWP) addition on intestinal development and maturation of chickens and its potential action mechanism.

METHODS

180 one-day-old male Arbor Acres broilers were randomly assigned to three groups containing control (basal diets without any antibiotics or anticoccidial drug), bacitracin methylene disalicylate (BMD)-treated group (50 mg/kg) and YCWP-supplemented group (100 mg/kg).

RESULTS

Compared with control group, in-feed antibiotic BMD continuous administration significantly decreased crypt depth (d 21) and villus height (d 42) along with mucosal maltase activity (d 42) in the ileum (P < 0.05). Also, BMD markedly downregulated gene expression levels of β-catenin, lysozyme, occludin and FABP-2 (d 21) and innate immune related genes CD83 and MHC-I mRNA levels (d 42, P < 0.05), and decreased goblet cell counts in the ileum of chickens (d 21 and d 42, P < 0.05). While, TLR-2, TLR-6 and iNOS mRNA abundances were notably upregulated by BMD treatment (d 42, P < 0.05). Nevertheless, dietary YCWP addition significantly increased the ratio of villus height to crypt depth (d 21), villus surface area (d 21 and d 42), ileal alkaline phosphatase and maltase activities as well as goblet cell (d 21 and d 42) and IgA-producing plasma cell numbers as compared to BMD treatment (d 21, P < 0.05). YCWP addition also upregulated gene expression levels of Lgr5, Wnt/β-catenin signaling pathway related gene (Wnt3, β-catenin, d 21; β-catenin, d 42), intestinal cells proliferation marker Ki-67 and barrier function related genes (occludin, d 21 and d 42, P < 0.05). Moreover, YCWP significantly increased antigen presenting cell marker related genes (MHC-II, d 21; CD83 and MHC-I, d 42), TLR-1, TLR-2 and TLR-6 mRNA levels (d 21, P < 0.05). Cecal microbiome analysis showed that YCWP addition obviously improved cecal microbial composition, as indicated by increasing relative abundance of Fournierella, Psychrobacter and Ruminiclostridium on d 21, and Alistipes and Lactobacillus on d 42, which were positively related with gut development and maturation related indexes (P < 0.05).

CONCLUSION

Collectively, YCWP promoted yet antibiotic BMD delayed intestinal morphological and immunological development linked with modulating gut microbiome in chickens.

Development of Sheep Intestinal Organoids for Studying Deoxynivalenol-Induced Toxicity

Sheep are an important livestock species whose gastrointestinal tract is essential for overall health. Feed contaminants such as bacterial toxins and mycotoxins severely damage the sheep intestine, yet the mechanisms remain mostly elusive partially due to the lack of physiologically relevant in vitro models. Here, we investigated molecular mechanisms underlying deoxynivalenol (DON)-induced toxicity by developing intestinal organoids from isolated intestinal crypts of Hu sheep. The organoids had a central lumen and monolayer epithelium, and could be continuously passaged, cryopreserved, and resuscitated. Histological and transcriptomic analysis showed that the intestinal organoids recapitulate the cell lineages and gene expression characteristics of the original intestinal tissues. Statistical analysis indicated that DON exposure significantly inhibited organoid formation efficiency, as well as the proliferation and activity of intestinal organoid cells. RNA-seq and Western blotting analysis further revealed that DON exposure induces intestinal toxicity by inhibiting the PI3K/AKT/GSK3β/β-catenin signaling pathway. Our study provides a novel example of organoid application in toxicity studies and reveals the signaling pathway involved in DON-induced toxicity in sheep, which is of great significance for improving mitigation strategies for DON.

Celiac Disease: A Transitional Point of View

Celiac disease (CeD) is a chronic, lifelong, multifactorial, polygenic, and autoimmune disorder, characteristically triggered by exposure to the exogenous factor "gluten" in genetically predisposed individuals, with resulting duodenal inflammation and enteropathy, as well as heterogeneous multisystemic and extraintestinal manifestations. The immunopathogenesis of CeD is complex, favored by a peculiar human leukocyte antigen (HLA) genetic predisposition, leading to gluten presentation by antigen-presenting cells to CD4+ T helper (Th) cells, T cell-B cell interactions, and production of specific antibodies, resulting in the immune-mediated killing of enterocytes and, macroscopically, in duodenal inflammation. Here, the most relevant correlations between cellular and molecular aspects and clinical manifestations of this complex disease are reviewed, with final considerations on nutritional aspects for disease management.

The MYO1B and MYO5B motor proteins and the sorting nexin SNX27 regulate apical targeting of membrane mucin MUC17 in enterocytes

A dense glycocalyx, composed of the megaDalton-sized membrane mucin MUC17, coats the microvilli in the apical brush border of transporting intestinal epithelial cells, called enterocytes. The formation of the MUC17-based glycocalyx in the mouse small intestine occurs at the critical suckling-weaning transition. The glycocalyx extends 1 µm into the intestinal lumen and prevents the gut bacteria from directly attaching to the enterocytes. To date, the mechanism behind the positioning of MUC17 to the brush border is not known. Here, we show that the actin-based motor proteins MYO1B and MYO5B, and the sorting nexin SNX27, regulate apical targeting of MUC17 in enterocytes. We demonstrate that MUC17 turnover at the brush border is slow and controlled by MYO1B and SNX27. Furthermore, we report that MYO1B regulates MUC17 protein levels in enterocytes, whereas MYO5B specifically governs MUC17 levels at the brush border. Together, our results extend our understanding of the apical targeting of membrane mucins and provide mechanistic insights into how defective positioning of MUC17 renders enterocytes sensitive to bacterial challenges.

Immunohistochemical evaluation of LGR5, CD71, CD138 and CXCR3 markers in the small bowel mucosa of participants with celiac disease and persons with normal bowel mucosa

Celiac disease (CD) is a chronic autoimmune disease of the small bowel mucosa that develops because of the altered immune response to gluten, which leads to intestinal epithelium damage and villous atrophy. However, studies on regeneration of the damaged small bowel mucosa and density of intestinal stem cells (ISC) in CD persons are still scarce. We aimed to evaluate the number of small bowel mucosa cells positive for LGR5, CD138/Syndecan-1, CD71 and CXCR3 in CD and in controls with normal bowel mucosa; to find relationship between these markers and degree of small intestinal atrophy and to compare these results with our previous data about the number of CD103 + , IDO + DCs, FOXP3 + Tregs, enterovirus (EV) density and serum zonulin level. The paraffin sections of the small bowel biopsies were obtained from 26 children with CD (median age 6.5 years), and from 20 controls with normal intestinal mucosa (median age 14.2 years) and from the tissue bank of the Department of Pathology of Tartu University Hospital (from 18 participants with CD including 14 children (median age 13.2 years) and from 11subjects with normal small bowel mucosa, including one child aged 4.8 years. The number of LGR5 + , CD71 + , CD138 + , and CXCR3 + cells was evaluated using immunohistochemistry. The median number of CD138 + and CXCR3 + cells was significantly higher in the small bowel mucosa in CD compared with normal mucosa (p = 0.0002 for CD138 and p = 0.006 for CXCR3). The median number of CD71 + cells was significantly higher in normal small bowel mucosa (p = 0.005). The number of LGR5 + cells did not differ between persons with CD and those with normal small bowel mucosa (p = 0.7). A markedly increased number of CD138 + and CXCR3 + cells in the small bowel mucosa of participants with CD confirms their role in the pathogenesis of this disease. There was no expected marked difference in the density of any of the studied markers between lower or higher grade of small bowel atrophy and level of tTG-IgA in CD.

Reduced Expression of REG4 as a Sign of Altered Goblet Cell Function in Necrotizing Enterocolitis

OBJECTIVE

 Defective Goblet cells have been proposed to be involved in necrotizing enterocolitis (NEC). The aim was to study the expression of the Goblet cell marker REG4 and its potential involvement in NEC in preterm infants with and without NEC.

STUDY DESIGN

 Seventy histologically intact intestinal biopsies were studied: 43 were collected during surgery due to NEC (NEC group: 26.5 ± 3.0 weeks' gestational age [wGA]), and 27 from individuals who underwent surgery due to other conditions (Control group; 36.1 ± 4.5 wGA). The tissue samples were immunohistochemically stained for REG4. REG4 expression was quantified with a semiautomated digital image analysis and with clinical data compared between the groups.

RESULTS

 REG4 expression was lower in the NEC group than in the Control group (p = 0.035). Low REG4 expression correlated to the risk of NEC (p = 0.023). In a multivariable logistic regression analysis including GA and REG4 expression for NEC risk, only GA (p < 0.001) and not REG4 expression (p = 0.206) was associated with NEC risk.

CONCLUSION

 This study concludes that Goblet cell dysfunction may be involved in NEC development, as low expression of the Goblet cell marker REG4 was related to an increased NEC risk in preterm infants. Maturity could however not be excluded as a potential confounder for REG4 expression.

KEY POINTS

· REG4 is a specific Goblet cell marker not yet studied in NEC.. · REG4 was quantified in intestinal biopsies from infants with and without NEC.. · REG4 expression was lower in infants with NEC, and expression seems to be maturity dependent..

Sodium carboxymethylcellulose disrupts intestinal cell homeostasis by repressing Notch signaling in Drosophila

Sodium carboxymethylcellulose (CMC), a cellulose derivative, is mainly used in food industry as additives. However, its supplementation has potentially negative effects on organisms. In this study, the effects of CMC on the physiological parameters and intestinal homeostasis in organisms were investigated using Drosophila melanogaster as a model. The results show that CMC did not affect survival and fecundity in flies at three detected concentrations. The puc activity analysis revealed that the CMC did not induce apoptosis in adult midgut. In adults treated with 5 % CMC, the midgut contained fewer progenitor cells and showed reduced mitosis compared to control flies. In addition, an increased enteroendocrine (EE) cells ratio was observed in midgut of 5 % CMC-fed flies. The RT-qPCR results revealed that notch expression was downregulated in 5 % CMC-fed flies, whereas no significant differences in mRNA expression levels were found for genes involved in midgut development. Consistently, the number of Notch positive clones was reduced in flies treated with 5 % CMC compared to controls. Taken together, our results suggest that CMC disrupts intestinal cell homeostasis by repressing Notch signaling. These findings provide a new perspective on the effects of CMC on organisms.

Ontogeny and function of the intestinal epithelial and innate immune cells during early development of chicks: to explore in ovo immunomodulatory nutrition

Intestinal epithelial cells (IECs) and innate immune cells in the gastrointestinal tract (GIT) of chickens play crucial roles in pathogens defense and maintaining gut health. However, their effectiveness influenced with their developmental and functional stages during pre and post hatch periods of chick. During embryonic development, differentiation and migration of these innate immune systems are tightly regulated by diverse cellular and molecular factors. The maturation and functionality of IECs are histologically evident starting embryonic day (ED) 14. Moreover, the innate immun cells, such as dendritic cells (DCs), macrophages, natural killer (NK) cells, and gamma-delta (γδ) T cells have showed developmental expression varation, while most identified by the 3rd days of incubation and capable of responsing to their cognate ligands of pathogens by ED 17, it may not efficient during posthatch period. In modern poultry production, in ovo feeding of bioactive substances is a topic of interest to maximize the protection capability of hatched chicks by enhancing improvement on the development of innate immune systems. However, their actions and effects on each distinct innate immune involved response are inconsistent and not clearly understood. Thus, summarizing the ontogeny and function of IECs, innate immunity systems, and interaction mechanisms of in ovo feeding of bioactive substances could provide baseline information for designing targeted in ovo feeding interventions to modulate cell waise specific innate immune systems.

WNT4 promotes the symmetric fission of crypt in radiation-induced intestinal epithelial regeneration

BACKGROUND

Radiotherapy for pelvic malignant tumors inevitably causes intestinal tissue damage. The regeneration of intestinal epithelium after radiation injury relies mainly on crypt fission. However, little is known about the regulatory mechanisms of crypt fission events.

METHODS

The effects of WNT4 on crypt regeneration and the symmetry of crypt fission were examined using a mouse small intestinal organoid culture model. Three-dimensional (3D) reconstructed images of organoids were applied to assess the symmetry of crypt fission and Paneth cell localization upon manipulation of WNT4 expression. The effect of WNT4 on the expression of β-catenin target genes was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). The in vivo effect of WNT4 overexpression mediated by adeno-associated virus (AAV) on symmetric fission of crypt was investigated using a radiation-injured mouse model.

RESULTS

WNT4 has a special function of promoting symmetric fission of small intestinal crypts, although it inhibits budding, stemness, and cell proliferation on organoids. WNT4 promotes the correct localization of Paneth cells in the crypt base by regulating the expression of EphB3, thereby promoting the symmetric fission of small intestinal crypts. WNT4 negatively regulates the canonical WNT/β-catenin signaling pathway, and it promotes symmetric crypt fission in a ROR2 receptor-dependent manner. Moreover, in patients and animal models of radiation-induced intestinal injury, we found that the regenerated crypts are irregular in size and shape, Paneth cells are mislocalized, and the expression of WNT4 is decreased while EphB3 is increased. Importantly, restoration of WNT4 expression mediated by AAV effectively promotes symmetric crypt fission and thus improves the regularity of regenerating crypts in mice with radiation-induced injury.

CONCLUSIONS

Our study highlights the critical role of WNT4 in the regulation of crypt fission and provides WNT4 as a potential therapeutic target for radiation enteritis.

The plasticity of epithelial cells and its potential in the induced differentiation of gastric cancer

Cell plasticity refers to the deviation of cells from normal terminal differentiation states when faced with environmental and genetic toxic stresses, resulting in the phenomenon of transforming into other cell or tissue phenotypes. Unlocking phenotype plasticity has been defined as a hallmark of malignant tumors. The stomach is one of the organs in the body with the highest degree of self-renewal and exhibits significant cell plasticity. In this paper, based on the review of the characteristics of normal differentiation of gastric epithelial cells and their markers, the four main phenotypes of gastric epithelial cell remodeling and their relationship with gastric cancer (GC) are drawn. Furthermore, we summarize the regulatory factors and mechanisms that affect gastric epithelial cell plasticity and outline the current status of research and future prospection for the treatment targeting gastric epithelial cell plasticity. This study has important theoretical reference value for the in-depth exploration of epithelial cell plasticity and the tumor heterogeneity caused by it, as well as for the precise treatment of GC.

Alterations in Ileal Secretory Cells of The DSS-Induced Colitis Model Mice

Inflammatory bowel disease is triggered by abnormalities in epithelial barrier function and immunological responses, although its pathogenesis is poorly understood. The dextran sodium sulphate (DSS)-induced colitis model has been used to examine inflammation in the colon. Damage to mucosa primality occurs in the large intestine and scarcely in the small intestine. To evaluate the effect on the ileum, we histologically analyzed the inflammatory and recovery phases in DSS model mice, and 40 kDa FITC-dextran was used to investigate barrier function. In the inflammatory phase, histological damage was insignificant. However, expanded crypts, hypertrophic goblet and Paneth cells, increased mucus production and secretion were observed. The cellular morphology was restored to that of the control in the recovery phase. According to in situ hybridization and lectin histochemistry, the expression of intestinal stem cell markers, secretory cell differentiation factors, and glycosylation of secretory granules in Paneth cells differed in the DSS model. DSS-treatment did not influence the barrier function in the ileum, and FITC-dextran did not diffuse via the paracellular pathway into the mucosa. However, cells incorporating FITC appeared even under normal conditions. The number of FITC-positive Paneth cells was lower in the DSS group than the control group. Our results showed morphological and functional alterations in ileal epithelial cells, especially secretory cells, in the DSS colitis model.

A statistical approach for systematic identification of transition cells from scRNA-seq data

Decoding cellular state transitions is crucial for understanding complex biological processes in development and disease. While recent advancements in single-cell RNA sequencing (scRNA-seq) offer insights into cellular trajectories, existing tools primarily study expressional rather than regulatory state shifts. We present CellTran, a statistical approach utilizing paired-gene expression correlations to detect transition cells from scRNA-seq data without explicitly resolving gene regulatory networks. Applying our approach to various contexts, including tissue regeneration, embryonic development, preinvasive lesions, and humoral responses post-vaccination, reveals transition cells and their distinct gene expression profiles. Our study sheds light on the underlying molecular mechanisms driving cellular state transitions, enhancing our ability to identify therapeutic targets for disease interventions.

Cell-based and extracellular vesicle-based MSC therapies for acute radiation syndrome affecting organ systems

Exposure to ionizing radiation can induce harmful biological effects on the human body, particularly in cases of high-dose γ-irradiation affecting the gastrointestinal tract, bone marrow, skin and lung. Such exposures lead to lethal outcomes as individuals experience a breakdown in their immune system's ability to defend against pathogens, predisposing them to sepsis-induced multiple organ failures. Mesenchymal stromal/stem cells (MSCs) possess diverse biological characteristics, including immunomodulation, anti-inflammation and tissue regeneration. Off-the-shelf culture-expanded human bone marrow- or adipose tissue-derived MSCs are clinically available to treat graft-versus-host disease following hematopoietic cell transplantation and perianal fistulas in Crohn's disease in Japan. While preclinical studies showcase encouraging outcomes in radiation-induced injuries, the effectiveness of MSC transplantation in addressing acute radiation syndrome affecting organs in irradiated individuals is limited. Recent studies have highlighted MSC-releasing extracellular vesicles as nanoparticle substances responsible for outlining the mechanism of action and have identified various components, including proteins and microRNA, that serve as functional molecules. MSC-releasing extracellular vesicle-based therapy emerges as a promising avenue, offering a potential solution to the challenges posed by radiation-induced injuries. However, further investigation is required, especially regarding whether MSC-releasing extracellular vesicles have regenerative effects on tissue-resident stem cells. These unresolved issues represent key aspects that need to be addressed to optimize the therapeutic potential of cell-based and extracellular vesicle-based MSC therapies for interventions in the context of radiation-induced injuries.

New insight in treating autoimmune diseases by targeting autophagy

Autophagy is a highly conserved biological process in eukaryotes, which degrades cellular misfolded proteins, damaged organelles and invasive pathogens in the lysosome-dependent manner. Autoimmune diseases caused by genetic elements, environments and aberrant immune responses severely impact patients' living quality and even threaten life. Recently, numerous studies have reported autophagy can regulate immune responses, and play an important role in autoimmune diseases. In this review, we summarised the features of autophagy and autophagy-related genes, enumerated some autophagy-related genes involved in autoimmune diseases, and further overviewed how to treat autoimmune diseases through targeting autophagy. Finally, we outlooked the prospect of relieving and curing autoimmune diseases by targeting autophagy pathway.

Bile acid disorders and intestinal barrier dysfunction are involved in the development of fatty liver in laying hens

The pathogenesis of fatty liver is highly intricate. The role of the gut-liver axis in the development of fatty liver has gained increasing recognition in recent years. This study was conducted to explore the role of bile acid signaling and gut barrier in the pathogenesis of fatty liver. A total of 100 "Jing Tint 6" laying hens, 56-week-old, were used and fed basal diets until 60 weeks of age. At the end of the experiment, thirty individuals were selected based on the degree of hepatic steatosis. The hens with minimal hepatic steatosis (< 5 %) were chosen as healthy controls, while those with severe steatosis (> 33 %) in the liver were classified as the fatty liver group. Laying hens with fatty liver and healthy controls showed significant differences in body weight, liver index, abdominal fat ratio, feed conversion ratio (FCR), albumin height, Haugh unit, and biochemical indexes. The results of bile acid metabolomics revealed a clear separation in hepatic bile acid profiles between the fatty liver group and healthy controls, and multiple secondary bile acids were decreased in the fatty liver group, indicating disordered bile acid metabolism. Additionally, the mRNA levels of farnesoid X receptor (FXR) and genes related to bile acid transport were significantly decreased in both the liver and terminal ileum of hens with fatty liver. Moreover, the laying hens with fatty liver exhibited significant decreases in ileal crypt depth, the number of goblet cells, and the mRNA expression of tight junction-related proteins, alongside a significant increase in ileal permeability. Collectively, these findings suggest that disordered bile acids, suppressed FXR-mediated signaling, and impaired intestinal barrier function are potential factors promoting the development of fatty liver. These insights indicate that regulating bile acids and enhancing intestinal barrier function may become new preventive and therapeutic strategies for fatty liver in the near future.

Hidradenitis suppurativa pathogenesis: Extrinsic factors

While genetic predisposition and immune dysregulation are recognized as key contributors to the development of hidradenitis suppurativa, accumulating research points to the influence of extrinsic factors in the pathogenesis of this condition. This review explores the roles of mechanical stress, altered skin and gut microbiome, tobacco smoking, diet, and paradoxical drug reactions as drivers of hidradenitis suppurativa onset and progression. A holistic management approach addressing these factors may be encouraged to improve disease outcomes. Further research is needed to fully determine the causal role of these extrinsic factors and their impact on treatment strategies.

STARD7 maintains intestinal epithelial mitochondria architecture, barrier integrity, and protection from colitis

Susceptibility to inflammatory bowel diseases (IBDs), Crohn's disease (CD), and ulcerative colitis (UC) is linked with loss of intestinal epithelial barrier integrity and mitochondria dysfunction. Steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain-containing protein 7 (STARD7) is a phosphatidylcholine-specific (PC-specific) lipid transfer protein that transports PC from the ER to the mitochondria, facilitating mitochondria membrane stabilization and respiration function. The aim of this study was to define the contribution of STARD7 in the regulation of the intestinal epithelial mitochondrial function and susceptibility to colitis. In silico analyses identified significantly reduced expression of STARD7 in patients with UC, which was associated with downregulation of metabolic function and a more severe disease phenotype. STARD7 was expressed in intestinal epithelial cells, and STARD7 knockdown resulted in deformed mitochondria and diminished aerobic respiration. Loss of mitochondria function was associated with reduced expression of tight junction proteins and loss of intestinal epithelial barrier integrity that could be recovered by AMPK activation. Stard7+/- mice were more susceptible to the development of DSS-induced and Il10-/- spontaneous models of colitis. STARD7 is critical for intestinal epithelial mitochondrial function and barrier integrity, and loss of STARD7 function increases susceptibility to IBD.