Tales from the crypt: new insights into intestinal stem cells

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.

High-throughput assay for predicting diarrhea risk using a 2D human intestinal stem cell-derived model

Gastrointestinal toxicities (GITs) in clinical trials often lead to dose-limitations that reduce drug efficacy and delay treatment optimization. Preclinical animal models do not accurately replicate human physiology, leaving few options for early detection of GITs, such as diarrhea, before human studies. Chemotherapeutic agents, known to cause clinical diarrhea, frequently target mitotic cells. Therefore, we hypothesized a model utilizing proliferative cell populations derived from human intestinal crypts would predict clinical diarrhea occurrence with high accuracy. Here, we describe the development of a diarrhea prediction assay utilizing RepliGut® Planar, a primary intestinal stem cell-derived platform. To evaluate the ability of this model to predict clinical diarrhea risk, we assessed toxicity of 30 marketed drugs by measuring cell proliferation (EdU incorporation), cell abundance (nuclei quantification), and barrier formation (TEER) in cells derived from three human donors. Dose response curves were generated for each drug, and the IC15 to Cmax ratio was used to identify a threshold for assay positivity. This model accurately predicted diarrhea potential, achieving an accuracy of 91 % for proliferation, 90 % for abundance, and 88 % for barrier formation. In vitro toxicity screening using primary proliferative cells may reduce clinical diarrhea and ultimately lead to safer and more effective treatments for patients.

Nondigestible stachyose alleviates cyclophosphamide-induced small intestinal mucosal injury in mice by regulating intestinal exosomal miRNAs, independently of the gut microbiota

Stachyose has traditionally been considered to exert prebiotic effects primarily through its interaction with gut microbiota. However, this study reveals a novel mechanism by which stachyose alleviates cyclophosphamide (CY)-induced small intestinal mucosa disruption by regulating the intestinal exosomal miRNAs, without relying on the gut microbiota. Specifically, stachyose significantly mitigates CY-caused damage to the intestinal permeability, oxidative stress, and the structure of intestinal villi and crypts in pseudo-germ-free (PGF) mice. The immunofluorescence staining and qPCR analyses show that stachyose treatment restores CY-caused abnormal changes on the levels of tight junction proteins including MUC2, Occludin, Claudin-1, and ZO-1, and pro-inflammatory cytokines including TNF-α, IL-1β, and IL-2. Furthermore, by conducting fecal miRNA transplantation experiment, we further demonstrated that, similar to stachyose, stachyose-shaped intestinal miRNAs protect against CY-induced intestinal mucosal damage in PGF mice. In summary, this study provides new scientific evidence for the direct interaction between nondigestible stachyose and the proximal small intestine. It also opens new avenues for further investigation into the systemic nutritional functions of stachyose, particularly the health benefits of stachyose in the upper gastrointestinal tract.

The Duodenal Microenvironment in Functional Dyspepsia

Functional dyspepsia (FD) is a chronic gastrointestinal disorder without a readily identifiable organic cause, resulting in bothersome upper abdominal symptoms. It is a highly prevalent disorder of which the pathophysiology remains mostly elusive, despite intensive research efforts. However, recent studies have found alterations in the microenvironment of the duodenum in patients with FD. In this review we summarize the duodenal microenvironment in homeostatic conditions and the alterations found in patients with FD, highlighting the similarities and discrepancies between different studies. The most consistent findings, being an impaired duodenal barrier and duodenal immune activation, are reviewed. We discuss the potential triggers for these observed alterations, including psychological comorbidities, luminal alterations and food related triggers. In summary, this review presents the evidence of molecular and cellular changes in patients with FD, with an impaired duodenal barrier and activated mucosal eosinophils and mast cells, challenging the notion that FD is purely functional, and offering different targets for potential future treatments.

Probiotic Lactobacillus rhamnosus GG Alleviates Prehypertension and Restores Gut Health and Microbiota in NaCl-Induced Prehypertensive Rats

Probiotics could be used as adjuvant treatments in prehypertension management to restore gut microbiota dysbiosis caused by a high-salt diet. This study investigated the antihypertensive effects of the probiotic Lactobacillus rhamnosus strain GG (LGG) on high-salt diet-induced prehypertensive rats. Eighteen Sprague-Dawley rats were assigned equally into three groups: normotensive fed on a normal diet (ND), prehypertensive induced on a 4% NaCl high-salt diet (HSD), and prehypertensive induced on an HSD treated with LGG at 1 × 109 CFU daily for 8 weeks (LGG). Weekly changes in water, food, body weight, diastolic blood pressure (DBP), systolic blood pressure (SBP), and mean arterial pressure (MAP) were monitored. Serum levels of Na, K, Cl, ALB, Ca, and TP were measured at the end of treatment, along with morphological and histomorphometric changes in the small intestine. Stool samples collected before (W0) and 8 weeks after treatment (W8) were sequenced for bacterial 16S rDNA metagenomics. Probiotic LGG significantly reduces average DBP, SBP, and MAP while improving gut integrity through intact intestine morphology, higher villus heights, and a V/C ratio. At the genus level, the LGG group's gut microbiota composition is more similar to the HSD profile at W0 but shifts to the ND profile after treatment at W8. Thus, probiotic LGG lowers blood pressure indices, improves serum biochemistry profile, restores small intestinal integrity barrier, and modulates gut microbiota profile, indicating its potential as an adjuvant treatment for prehypertension and the significance of gut health in blood pressure regulation.

Oral absorption mechanisms of polysaccharides and potential as carriers for the construction of nano-delivery systems: A review

Polysaccharides have garnered increasing attention in recent years for their potential in oral drug delivery within biomaterials and pharmaceuticals, owing to their excellent physicochemical properties, bioactivity, and low toxicity. However, the absorption of polysaccharides encounters multiple challenges posed by the biological, chemical, mechanical, and immune barriers of the intestinal mucosa. Therefore, elucidating the mechanisms by which polysaccharides traverse the intestinal mucosa for oral absorption is essential for their further development and application. Current studies have identified several polysaccharide absorption pathways, including transcellular transport, paracellular transport, M cell and Peyer's patches mediated transport, and intestinal flora mediated transport. Furthermore, numerous studies have demonstrated that polysaccharides can enhance the solubility, gastrointestinal stability, and permeability of small molecule components, which significantly improves their bioavailability. More importantly, nano-delivery systems utilizing polysaccharides as carriers have shown great promise in enhancing the targeting of small molecule components, thereby opening new avenues for drug delivery applications. We hope this review will provide theoretical support and inspiration for a deeper understanding of oral absorption mechanisms and the potential of polysaccharides in the development of nano-delivery systems.

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.

Osteoarthritis treatment via the GLP-1-mediated gut-joint axis targets intestinal FXR signaling

Whether a gut-joint axis exists to regulate osteoarthritis is unknown. In two independent cohorts, we identified altered microbial bile acid metabolism with reduced glycoursodeoxycholic acid (GUDCA) in osteoarthritis. Suppressing farnesoid X receptor (FXR)-the receptor of GUDCA-alleviated osteoarthritis through intestine-secreted glucagon-like peptide 1 (GLP-1) in mice. GLP-1 receptor blockade attenuated these effects, whereas GLP-1 receptor activation mitigated osteoarthritis. Osteoarthritis patients exhibited a lower relative abundance of Clostridium bolteae, which promoted the formation of ursodeoxycholic acid (UDCA), a precursor of GUDCA. Treatment with C. bolteae and Food and Drug Administration-approved UDCA alleviated osteoarthritis through the gut FXR-joint GLP-1 axis in mice. UDCA use was associated with lower risk of osteoarthritis-related joint replacement in humans. These findings suggest that orchestrating the gut microbiota-GUDCA-intestinal FXR-GLP-1-joint pathway offers a potential strategy for osteoarthritis treatment.

Sympathetic-Mediated Intestinal Cell Death Contributes to Gut Barrier Impairment After Stroke

Tissue injury induced by stroke is traditionally thought to be localised to the brain. However, there is an accumulating body of evidence to demonstrate that stroke promotes pathophysiological consequences in peripheral tissues including the gastrointestinal system. In this study, we investigated the mechanisms underlying gut permeability after stroke. We utilised the clinically relevant experimental model of stroke called permanent intraluminal middle cerebral artery occlusion (pMCAO) to examine the effect of cerebral ischaemia on the gut. We detected stroke-induced gut permeability at 5 h after pMCAO. At this timepoint, we observed significantly elevated intestinal epithelial cell death in post-stroke mice compared to their sham-operated counterparts. At 24 h after stroke onset when the gut barrier integrity is restored, our findings indicated that post-stroke intestinal epithelium had higher expression of genes associated with fructose metabolism, and hyperplasia of intestinal crypts and goblet cells, conceivably as a host compensatory mechanism to adapt to the impaired gut barrier. Furthermore, we discovered that stroke-induced gut permeability was mediated by the activation of the sympathetic nervous system as pharmacological denervation decreased the stroke-induced intestinal epithelial cell death, goblet cell and crypt hyperplasia, and gut permeability to baseline levels. Our study identifies a previously unknown mechanism in the brain-gut axis by which stroke triggers intestinal cell death and gut permeability.

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.

Methyltransferase-like 3-mediated RNA N6-methyladenosine contributes to immune dysregulation: diagnostic biomarker and therapeutic target

Methyltransferase-like 3 (METTL3) plays a crucial role in post-transcriptional gene regulation. Substantial evidence links METTL3 to various immune dysfunctions, such as the suppression of antiviral immunity during viral infections and the disruption of immune tolerance in conditions like autoimmune diseases, myeloid leukemia, skin cancers, and anticancer immunotherapy. However, a thorough review and analysis of this evidence is currently missing, which limits the understanding of METTL3's mechanisms and significance in immune dysfunctions. This review aims to elucidate the roles and mechanisms of METTL3 in these immune issues, highlighting its connections and proposing new insights into its modulation of immune responses. Analysis results in this review suggest that METTL3 hampers antiviral immunity, worsens viral replication and infection, and disrupts immune tolerance; conversely, regulating METTL3 enhances antiviral immunity and facilitates viral clearance. Moreover, clinical data corroborates these findings, showing that METTL3 overexpression is associated with increased susceptibility to viral infections and autoimmune conditions. This review establishes a theoretical basis for considering METTL3 as a novel regulator, an important diagnostic biomarker, and a potential target for treating immune dysfunctions.

Effects of high-level ghrelin on intestinal epithelial cell proliferation, nutrient transport and intestinal mucosal immune barrier in chickens

1. Chicken ghrelin (GH) plays an important role in regulating growth hormone secretion, immunity and gastrointestinal motility. This study utilised haematoxylin-eosin staining, quantitative reverse transcription PCR and western blotting to examine the effects of high-level ghrelin on the proliferation of small intestinal epithelial cells, intestinal nutrient transport and the mucosal immune barrier in chicks.2. Eighty, 17-d-old layer type chicks were randomly divided into two groups: control (C treated with sterile phosphate buffer) and the ghrelin-treated group (GH; intraperitoneally injected with 0.5 nM GH per 100 g body weight). At 1, 3 and 5 d post-injection, six chicks from each group were randomly selected for sampling of the duodenum and ileum.3. Administering GH reduced the expression of proliferating cell nuclear antigen protein in the duodenum and leucine-rich repeat-containing G protein-coupled receptor 5 mRNA in both the duodenum and ileum. In addition, GH affected villus height and ratio of villus height to crypt (H/C) depth in these sections and fatty acid binding protein 6 expression in the ileum. The relative mRNA levels of oligopeptide transporter 1, solute carrier family 3 member 1, solute carrier family 1 member 1 and solute carrier family 5 member 1 were decreased by GH.4. Birds treated with GH had a decrease in duodenal intraepithelial lymphocytes, Paneth cells and ileal goblet cells. There was a reduction in mucin 2 mRNA in goblet cells and lysozyme C and phospholipaseA2 mRNA in Paneth cells. Additionally, the relative mRNA levels of avian β-defensin 1 (AvBD1), AvBD6 and AvBD7 in the duodenum and ileum decreased with GH administration.5. The GH inhibited proliferation of chicken duodenal epithelial cells and decreased surface area available for intestinal villus absorption. This affected the transport of intestinal amino acids, glucose and bile acids and impaired the function of the mucosal immune barrier in both the duodenum and ileum.

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.

Growth of the maternal intestine during reproduction

The organs of many female animals are remodeled by reproduction. Using the mouse intestine, a striking and tractable model of organ resizing, we find that reproductive remodeling is anticipatory and distinct from diet- or microbiota-induced resizing. Reproductive remodeling involves partially irreversible elongation of the small intestine and fully reversible growth of its epithelial villi, associated with an expansion of isthmus progenitors and accelerated enterocyte migration. We identify induction of the SGLT3a transporter in a subset of enterocytes as an early reproductive hallmark. Electrophysiological and genetic interrogations indicate that SGLT3a does not sustain digestive functions or enterocyte health; rather, it detects protons and sodium to extrinsically support the expansion of adjacent Fgfbp1-positive isthmus progenitors, promoting villus growth. Our findings reveal unanticipated specificity to physiological organ remodeling. We suggest that organ- and state-specific growth programs could be leveraged to improve pregnancy outcomes or prevent maladaptive consequences of such growth.

Rumen-protected methionine and lysine supplementation to the low protein diet improves animal growth through modulating colonic microbiome in lambs

BACKGROUND

Dietary protein level and amino acid (AA) balance are crucial determinants of animal health and productivity. Supplementing rumen-protected AAs in low-protein diets was considered as an efficient strategy to improve the growth performance of ruminants. The colon serves as a crucial conduit for nutrient metabolism during rumen-protected methionine (RPMet) and rumen-protected lysine (RPLys) supplementation, however, it has been challenging to clarify which specific microbiota and their metabolites play a pivotal role in this process. Here, we applied metagenomic and metabolomic approaches to compare the characteristic microbiome and metabolic strategies in the colon of lambs fed a control diet (CON), a low-protein diet (LP) or a LP diet supplemented with RPMet and RPLys (LR).

RESULTS

The LP treatment decreased the average daily weight gain (ADG) in lambs, while the LR treatment tended to elicit a remission in ADG. The butyrate molar concentration was greater (P < 0.05), while acetate molar concentration (P < 0.05) was lower for lambs fed the LP and LR diets compared to those fed the CON diet. Moreover, the LP treatment remarkably decreased total AA concentration (P < 0.05), while LR treatment showed an improvement in the concentrations of methionine, lysine, leucine, glutamate, and tryptophan. Metagenomic insights proved that the microbial metabolic potentials referring to biosynthesis of volatile fatty acids (VFAs) and AAs in the colon were remarkably altered by three dietary treatments. Metagenomic binning identified distinct microbial markers for the CON group (Alistipes spp., Phocaeicola spp., and Ruminococcus spp.), LP group (Fibrobacter spp., Prevotella spp., Ruminococcus spp., and Escherichia coli), and LR group (Akkermansia muciniphila and RUG099 spp.).

CONCLUSIONS

Our findings suggest that RPMet and RPLys supplementation to the low-protein diet could enhance the microbial biosynthesis of butyrate and amino acids, enriche the beneficial bacteria in the colon, and thereby improve the growth performance of lambs.

The intestinal barrier: a pivotal role in health, inflammation, and cancer

The intestinal barrier serves as a boundary between the mucosal immune system in the lamina propria and the external environment of the intestinal lumen, which contains a diverse array of microorganisms and ingested environmental factors, including pathogens, food antigens, toxins, and other foreign substances. This barrier has a central role in regulating the controlled interaction between luminal factors and the intestinal immune system. Disruptions of intestinal epithelial cells, which serve as a physical barrier, or the antimicrobial peptides and mucins they produce, which act as a chemical barrier, can lead to a leaky gut. In this state, the intestinal wall is unable to efficiently separate the intestinal flora and luminal contents from the intestinal immune system. The subsequent activation of the immune system has an important role in the pathogenesis of inflammatory bowel disease, as well as in metabolic dysfunction-associated steatohepatitis, primary sclerosing cholangitis, and colorectal cancer. Dysregulated intestinal barrier integrity has also been described in patients with chronic inflammatory diseases outside the gastrointestinal tract, including rheumatoid arthritis and neurodegenerative disorders. Mechanistic studies of barrier dysfunction have revealed that the subsequent local activation and systemic circulation of activated immune cells and the cytokines they secrete, as well as extracellular vesicles, promote proinflammatory processes within and outside the gastrointestinal tract. In this Review, we summarise these findings and highlight several new therapeutic concepts currently being developed that attempt to control inflammatory processes via direct or indirect modulation of intestinal barrier function.

Genistein alleviates colitis by suppressing inflammation and modulating colonic Marvinbryantia formatexigens abundance and metabolites

As an active ingredient of leguminous plants, genistein is extremely important for alleviating various human diseases. However, the regulatory effect of genistein on intestinal microbiota in alleviating enteritis is still unclear. In this study, the effect of genistein in alleviating dextran sodium sulfate (DSS)-induced colitis and the potential microbial metabolic regulation mechanism were explored. First, the effect of genistein on DSS-induced colitis was studied in mice. Then antibiotics were used to inhibit intestinal bacteria to verify that intestinal microorganisms play an important role in alleviating colitis of genistein. Finally, mice were administrated with live differential bacterium to confirm that genistein can regulate intestinal microorganisms to treat colitis. The results indicated that genistein alleviated DSS-induced colonic inflammation by inhibiting the Nuclear factor kappa-B and Cyclooxygenase-2/Prostaglandin E2 pathway. Genistein alleviated DSS-induced intestinal injury and decreased Mucin 2 secretion. Supplementation with genistein attenuated the DSS-induced decrease in the alpha diversity of gut bacteria. Genistein increased the abundance of Lachnospiraceae and Marvinbryantia formatexigens, increased the concentration of short chain fatty acids in colitis. After antibiotics depleted the intestinal bacteria, genistein lost the effect of relieving colitis, indicating that genistein must relieve colitis through the intestinal bacteria. Mice fed with living Marvinbryantia formatexigens increased short-chain fatty acids and relieved colitis. The present study demonstrates that genistein alleviated colonic inflammation by regulating intestinal bacterium of Marvinbryantia formatexigens and increasing short-chain fatty acid production.

Dietary cysteine enhances intestinal stemness via CD8+ T cell-derived IL-22

A critical question in physiology is understanding how tissues adapt and alter their cellular composition in response to dietary cues. The mammalian small intestine, a vital digestive organ that absorbs nutrients, is maintained by rapidly renewing Lgr5+ intestinal stem cells (ISCs) at the intestinal crypt base. While Lgr5+ ISCs drive intestinal adaptation by altering self-renewal and differentiation divisions in response to diverse diets such as high-fat diets and fasting regimens, little is known about how micronutrients, particularly amino acids, instruct Lgr5+ ISC fate decisions to control intestinal homeostasis and repair after injury. Here, we demonstrate that cysteine, an essential amino acid, enhances the ability of Lgr5+ ISCs to repair intestinal injury. Mechanistically, the effects of cysteine on ISC-driven repair are mediated by elevated IL-22 from intraepithelial CD8αβ+ T cells. These findings highlight how coupled cysteine metabolism between ISCs and CD8+ T cells augments intestinal stemness, providing a dietary approach that exploits ISC and immune cell crosstalk for ameliorating intestinal damage.

Oat β-glucan enhances gut barrier function and maintains intestinal homeostasis in naturally aging mice

In the process of aging, adverse changes such as weakened intestinal barrier function, increased chronic inflammation, and decreased gut microbiota diversity often occur. We explored the protective effects of Oat β-glucan (BG) on the gut homeostasis of naturally aging mice. The study shows that daily intervention with 400 mg/kg BG effectively modulates the intestinal mucosal structure, mechanical barrier function [Zonula occludens-1 (ZO-1), occludin, and claudin], and anti-inflammatory [Tumor Necrosis Factor-α (TNF-α), Interleukin-6 (IL-6), and IL-1β], as well as antioxidant responses in aging mice. Spearman correlation analyses showed that BG supplementation increased acetate levels by 1.8-fold, propionate levels by 2.5-fold, and butyrate-derived GABA levels by 2.5-fold. Additionally, BG supplementation improved the gut microbiota, increasing the abundance of beneficial bacteria like Bacteroidota, Prevotellaceae, Coprobacillaceae, and Faecalibacterium. These microbes metabolize BG to produce short-chain fatty acids (SCFAs), activating butanoate and propanoate metabolic pathways to maintain intestinal homeostasis. In conclusion, this study identifies the therapeutic effects of BG in regulating intestinal barrier homeostasis and gut microbiota, providing new insights for nutritional intervention strategies in the elderly.

Cumulative experience meets modern science: Remarkable effects of TongXieYaoFang formula on facilitating intestinal mucosal healing and secretory function

ETHNOPHARMACOLOGICAL RELEVANCE

TongXieYaoFang (TXYF), a classical formula used in Traditional Chinese Medicine, is renowned for its efficacy in treating chronic abdominal pain and diarrhoea. Modern research suggests that fundamental relief from these symptoms depends on complete intestinal mucosal healing, which normalises gut secretory functions. Consensus between traditional and modern medical theories indicates that TXYF is particularly suitable for treating the remission phase of ulcerative colitis (UC). Unfortunately, its potential in the remission phase has not received sufficient attention, and its use has been largely limited to a supportive role during the acute phase.

AIM OF THE STUDY

This study aimed to elucidate the efficacy of TXYF in promoting intestinal mucosal healing and enhancing gut secretory function during the non-acute damage phase, as well as to identify the underlying mechanisms contributing to its effects.

METHODS

A mouse model of dextran sulphate sodium salt (DSS)-induced colitis was optimised to specifically evaluate the effects of TXYF on mucosal healing during the repair phase. The effects of TXYF on murine colon function were assessed by measuring faecal pellet count and water content, and further evaluated through immunohistochemical analyses. The underlying mechanisms of action of TXYF were elucidated using mouse intestinal organoid cultures, intestinal stem cell (ISCs) transplantation, immunofluorescence, and western blotting. Active components of TXYF were identified via LC-MS/MS analysis and integrated with network pharmacology for bioinformatics assessment.

RESULTS

TXYF significantly promoted mucosal healing, as reflected by reduced disease activity scores, increased colon length, enhanced epithelial proliferation, and decreased histological damage. Furthermore, TXYF enhanced the recovery of critical intestinal functions, including barrier integrity, absorption, secretion, and motility. Notably, the improvement in the secretory function was particularly pronounced. Mechanistically, these therapeutic effects were mediated by the upregulation of the Atonal homolog 1/SAM pointed domain containing ETS transcription factor/Mucin 2 pathway, which facilitates the differentiation and maturation of ISCs into goblet cells, thereby contributing to both mucosal repair and enhanced secretory function.

CONCLUSIONS

Our study demonstrated that TXYF significantly promotes intestinal mucosal healing and enhances secretory function. These findings offer a solid basis for exploring the potential applications of TXYF in UC management during the remission phase.

Prmt5 is essential for intestinal stem cell maintenance and homeostasis

Intestinal homeostasis relies on the continuous renewal of intestinal stem cells (ISCs), which could be epigenetically regulated. While protein arginine methyltransferase 5 (Prmt5) is known to play a key role in multiple organs as an epigenetic modifier, its specific function in maintaining intestinal homeostasis remains to be elucidated. Here, we show that Prmt5 is highly expressed in mouse crypts. The deletion of Prmt5 results in ISCs deficiency, ectopic localization of Paneth cells, and spontaneous colitis. Mechanistically, Prmt5 sustains a high level of H3K27ac accumulation by inhibiting Hdac9 expression in the intestinal epithelium, and maintains the stemness of ISCs in a cell-autonomous manner. Notably, inhibition of histone deacetylases can rescue both self-renewal and differentiation capacities of Prmt5-depleted ISCs. These findings highlight Prmt5 as a critical regulator in intestinal epithelium development and tissue homeostasis.

Unraveling the function of TSC1-TSC2 complex: implications for stem cell fate

BACKGROUND

Tuberous sclerosis complex is a genetic disorder caused by mutations in the TSC1 or TSC2 genes, affecting multiple systems. These genes produce proteins that regulate mTORC1 activity, essential for cell function and metabolism. While mTOR inhibitors have advanced treatment, maintaining long-term therapeutic success is still challenging. For over 20 years, significant progress has linked TSC1 or TSC2 gene mutations in stem cells to tuberous sclerosis complex symptoms.

METHODS

A comprehensive review was conducted using databases like Web of Science, Google Scholar, PubMed, and Science Direct, with search terms such as "tuberous sclerosis complex," "TSC1," "TSC2," "stem cell," "proliferation," and "differentiation." Relevant literature was thoroughly analyzed and summarized to present an updated analysis of the TSC1-TSC2 complex's role in stem cell fate determination and its implications for tuberous sclerosis complex.

RESULTS

The TSC1-TSC2 complex plays a crucial role in various stem cells, such as neural, germline, nephron progenitor, intestinal, hematopoietic, and mesenchymal stem/stromal cells, primarily through the mTOR signaling pathway.

CONCLUSIONS

This review aims shed light on the role of the TSC1-TSC2 complex in stem cell fate, its impact on health and disease, and potential new treatments for tuberous sclerosis complex.

HMGA1 is a crucial mediator of colon tumorigenesis driven by the loss of APC

Colorectal cancer is the second leading cause of cancer death in the United States. The adenomatous polyposis coli (APC) pathway plays a critical role in colorectal tumorigenesis, but the mechanism is not fully understood. In this issue of the JCI, Luo and colleagues used genetically engineered mouse models to show that high mobility group A (HMGA1) is a critical mediator in the development of colon tumors driven by the loss of the Apc gene. HMGA1 activated the transcription of Achaete-Scute Family BHLH Transcription Factor 2 (ASCL2), which regulated intestinal stemness and promoted colon tumorigenesis.

Dietary fermented mixed ingredient product enhances growth performance and intestinal stem cell-mediated epithelial regeneration through Wnt/β-catenin pathway in layer chicks

This study aimed to investigate the effects of dietary supplements of fermented mixed ingredient product (FMIP) on the growth performance, intestinal health, and immune performance of layer hens during the brooding period. Four hundred eighty healthy one-day-old layer chicks were randomly divided into four groups (six replicates/group, twenty hens/replicate) and were fed with different experimental diets for eight weeks (from day 1 to day 56): (1) Corn-soybean-base diet (CON); (2) Chlortetracycline group (CTC; CON diet supplemented with 0.5g/kg chlortetracycline); (3) 4 % fermented mixed ingredient product (4 % FMIP); (4) 8 % fermented mixed ingredient product (8 % FMIP). The results showed that, compared with the CON group, feeding with CTC, 4 % or 8 % FMIP increased the average daily feed intake (ADFI), average daily gain (ADG), immune organs index, serum IgA, IgM, and IgG levels, as well as the apparent metabolic rates of dry matter, crude protein, crude fiber, and crude ash (P < 0.05). Meanwhile, FMIP supplementation improved jejunal morphology and barrier function, as reflected by increased villus height and transepithelial electrical resistance, decreased DAO activity in serum, and up-regulated Occludin protein expression (P < 0.05). Additionally, FMIP supplementation significantly increased protein expression of the stem cell markers (SOX9 and Lgr5), proliferative cell marker (PCNA), and differentiated absorptive cell marker (Villin) (P < 0.05). The immunofluorescence results were consistent with the above results, and FMIP groups have the same effects as the CTC group. Furthermore, the CTC or 4 % FMIP treatment group resulted in a remarkable increase in Wnt/β-catenin signaling proteins (including β-catenin, TCF4, c-Myc, and Cyclin-D1) compared with the CON group (P < 0.05). In conclusion, dietary supplementation of 4 % FMIP improves growth and immune performance, and promotes the intestinal stem cell expansion of layer chicks through Wnt/β-catenin pathway activation.

Transport functions of intestinal lymphatic vessels

Lymphatic vessels are crucial for fluid absorption and the transport of peripheral immune cells to lymph nodes. However, in the small intestine, the lymphatic fluid is rich in diet-derived lipids incorporated into chylomicrons and gut-specific immune cells. Thus, intestinal lymphatic vessels have evolved to handle these unique cargoes and are critical for systemic dietary lipid delivery and metabolism. This Review covers mechanisms of lipid absorption from epithelial cells to the lymphatics as well as unique features of the gut microenvironment that affect these functions. Moreover, we discuss details of the intestinal lymphatics in gut immune cell trafficking and insights into the role of inter-organ communication. Lastly, we highlight the particularities of fat absorption that can be harnessed for efficient lipid-soluble drug distribution for novel therapies, including the ability of chylomicron-associated drugs to bypass first-pass liver metabolism for systemic delivery. In all, this Review will help to promote an understanding of intestinal lymphatic-systemic interactions to guide future research directions.

Intestinal stem cell niche: An upcoming area of immense importance in gastrointestinal disorders

The intestinal stem cell (ISC) niche is vital for maintaining the integrity and function of the intestinal epithelium. ISC populations, characterized by their high proliferation and multipotency, reside within a specialized microenvironment at the base of crypts. Crypt base columnar (CBC) cells at the deepest part of crypts serve as replicating ISCs, while position 4 label-retaining cells (LRCs) located higher up in the crypts are also important for ISC maintenance during experiments. The interplay between CBCs, position 4 LRCs, transient amplifying (TA) cells and other niche components, including the pericrypt stromal cells, ensures a continuous supply of differentiated epithelial cells. Recent advancements in ISC biomarker studies have provided valuable insights into their molecular signatures, regulatory pathways and roles in the pathogenesis of intestinal disorders. Understanding the ISC niche has significant therapeutic implications, as manipulating ISC behaviors and regenerating damaged or diseased intestinal tissue show promise for novel therapeutic approaches. ISC organoids have also provided a platform for studying intestinal diseases and testing personalized therapies. This comprehensive review covers the anatomical composition, physiological regulation, ISC biomarker studies, contribution to intestinal disorder pathogenesis and potential therapeutic implications of the ISC niche.

First-in-class ultralong-target-residence-time p38α inhibitors as a mitosis-targeted therapy for colorectal cancer

Colorectal cancer (CRC) constitutes the second leading cause of cancer-related death worldwide and advanced CRCs are resistant to targeted therapies, chemotherapies and immunotherapies. p38α (Mapk14) has been suggested as a therapeutic target in CRC; however, available p38α inhibitors only allow for insufficient target inhibition. Here we describe a unique class of p38α inhibitors with ultralong target residence times (designated ULTR-p38i) that robustly inhibit p38α downstream signaling and induce distinct biological phenotypes. ULTR-p38i monotherapy triggers an uncontrolled mitotic entry by activating Cdc25 and simultaneously blocking Wee1. Consequently, CRC cells undergo mitotic catastrophe, resulting in apoptosis or senescence. ULTR-p38i exhibit high selectivity, good pharmaco-kinetic properties and no measurable toxicity with strong therapeutic effects in patient-derived CRC organoids and syngeneic CRC mouse models. Conceptually, our study suggests ultralong-target-residence-time kinase inhibitors as an alternative to covalent inhibitors, which, because of the lack of cysteine residues, cannot be generated for many kinase cancer targets.

Recombinant Saccharomyces cerevisiae EBY100/pYD1-FaeG: a candidate for an oral subunit vaccine against F4+ ETEC infection

Diarrheal diseases attributable to multidrug-resistant F4+ enterotoxigenic Escherichia coli (ETEC) are escalating in severity, posing significant risks to the health and safety of both humans and animals. This study used Saccharomyces cerevisiae EBY100 to display the FaeG subunit of F4 colonizing factor as an oral vaccine against F4+ ETEC infection. Mice were orally immunized twice with 108 CFU of EBY100/pYD1-FaeG, followed by a challenge with F4+ ETEC EC6 on day 7 post-immunization. The results showed that the recombinant strain EBY100/pYD1-FaeG orally enhanced the growth of the small intestine villi, significantly boosted the expression of tight junction proteins (ZO-1, Occludin, MUC2, and Claudin) (P < 0.05), and modulated the gut microbiota composition. Additionally, immunization with EBY100/pYD1-FaeG also upregulated the levels of IL-2, IL-4, and IFN-γ in the intestines of mice (P < 0.01), while serum IgG and fecal sIgA titer significantly increased (P < 0.05). These immune responses enhanced the capacity to fight against ETEC, leading to an increased survival rate of mice and relieved damage to tissues and organs of mice infection. In summary, the study suggested that the recombinant Saccharomyces cerevisiae EBY100/pYD1-FaeG could effectively stimulate the immune response and generate specific antibodies against F4+ ETEC, showing its potential to serve as a subunit oral vaccine candidate for preventing F4+ ETEC infection.IMPORTANCEThe multidrug-resistant F4+ enterotoxigenic Escherichia coli (ETEC) strains are the primary clinical pathogens responsible for post-weaning diarrhea in piglets, resulting in substantial economic losses in the pig farming industry. In the study, we developed an oral vaccine candidate, Saccharomyces cerevisiae EBY100/pYD1-FaeG, to prevent diarrhea caused by multidrug-resistant F4+ ETEC. Oral administration of EBY100/pYD1-FaeG significantly enhanced immune responses, improved intestinal health, and provided protection against F4+ ETEC infection in mice. This approach offers a potential application prospect for preventing F4+ ETEC infections that lead to post-weaning diarrhea in clinical settings and provides a promising solution for addressing the growing threat of antibiotic resistance in bacterial pathogens.

Shaping epithelial tissues by stem cell mechanics in development and cancer

Adult stem cells balance self-renewal and differentiation to build, maintain and repair tissues. The role of signalling pathways and transcriptional networks in controlling stem cell function has been extensively studied, but there is increasing appreciation that mechanical forces also have a crucial regulatory role. Mechanical forces, signalling pathways and transcriptional networks must be coordinated across diverse length and timescales to maintain tissue homeostasis and function. Such coordination between stem cells and neighbouring cells dictates when cells divide, migrate and differentiate. Recent advances in measuring and manipulating the mechanical forces that act upon and are produced by stem cells are providing new insights into development and disease. In this Review, we discuss the mechanical forces involved when epithelial stem cells construct their microenvironment and what happens in cancer when stem cell niche mechanics are disrupted or dysregulated. As the skin has evolved to withstand the harsh mechanical pressures from the outside environment, we often use the stem cells of mammalian skin epithelium as a paradigm for adult stem cells shaping their surrounding tissues.

Cell signaling communication within papillary craniopharyngioma revealed by an integrated analysis of single-cell RNA sequencing and bulk RNA sequencing

OBJECTIVE

This study aims to elucidate the primary signaling communication among papillary craniopharyngioma (PCP) tumor cells.

METHODS

Five samples of PCP were utilized for single-cell RNA sequencing. The most relevant ligand and receptor interactions among different cells were calculated using the CellChat package in R software. Bulk RNA sequencing of 11 tumor samples and five normal controls was used to investigate the pair interactions detected by single-cell RNA sequencing.

RESULTS

Fibroblasts were not found in ACP, whereas they were detected in PCP. InferCNV revealed high CNV scores for the clusters of epithelial cells and fibroblasts using immune cells as a reference. Epithelial Mesenchymal Transition, Interferon Gamma Response, p53 Pathway, and Estrogen Response Early are pathways commonly shared by fibroblasts and epithelial cells, ranking high in priority. The Wnt signaling pathway and PI3K-Akt signaling pathway play a crucial role in facilitating communication between epithelial cells and fibroblasts. Neutrophils were recognized as the main receivers of incoming signals, with ANXA1-FPR1 and MIF-(CD74 + CXCR2) being identified as the primary signals transmitted from fibroblasts to neutrophils.

CONCLUSION

Through analyzing the communication of essential signaling pathways, ligands, and receptors among epithelial cells, fibroblasts, and neutrophils in PCP tumor tissues, we have identified certain molecules with promising prognostic and therapeutic potential.

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.

Motif distribution and DNA methylation underlie distinct Cdx2 binding during development and homeostasis

Transcription factors guide tissue development by binding to developmental stage-specific targets and establishing an appropriate enhancer landscape. In turn, DNA and chromatin modifications direct the genomic binding of transcription factors. However, how transcription factors navigate chromatin features to selectively bind a small subset of all the possible genomic target loci remains poorly understood. Here we show that Cdx2-a lineage defining transcription factor that binds distinct targets in developing versus adult intestinal epithelial cells-has a preferential affinity for a non-canonical CpG-containing motif in vivo. A higher frequency of this motif at embryonic Cdx2 targets and methylated state of the CpG during development enables selective Cdx2 binding and activation of developmental enhancers and genes. In adult cells, demethylation at these enhancers prevents ectopic Cdx2 binding, instead directing Cdx2 to its canonical motif without a CpG. This shift in Cdx2 binding facilitates Ctcf and Hnf4 recruitment, establishing super-enhancers during development and homeostatic enhancers in adult cells, respectively. Induced DNA methylation in adult mouse epithelium or cultured cells recruits Cdx2 to developmental targets, promoting corecruitment of partner transcription factors. Thus, Cdx2's differential CpG motif preferences enable it to navigate distinct DNA methylation profiles, activating genes specific to appropriate developmental stages.

Differential pathological changes in colon microenvironments in acute and chronic mouse models of inflammatory bowel disease

Inflammatory bowel disease is a chronic condition characterized by inflammation of the gastrointestinal tract, resulting from an abnormal immune response to normal stimuli, such as food and intestinal flora. Since the etiology of this disease remains largely unknown, murine models induced by the consumption of dextran-sodium sulfate serve as a pivotal tool for studying colon inflammation. In this study, we employed both acute and chronic colitis mouse models induced by varying durations of dextran-sodium sulfate consumption to investigate the pathological and immunologic characteristics throughout the disease course. During the acute phase, activated innate inflammation marked by M1 macrophage infiltration was prominent. In contrast, the chronic phase was characterized by tissue remodeling, with a significant increase in M2 macrophages and lymphocytes. RNA-sequencing revealed genetic changes in acute and chronic colitis, marked by the maintenance of genomic integrity in the acute phase and extracellular matrix dynamics in the chronic phase. These phase-specific alterations reflect the multifaceted physiological processes involved in the initiation and progression of inflammation in the large intestine, underscoring the necessity for distinct experimental approaches for each phase. The findings demonstrate that the factors shaping the large intestinal immune microenvironment change specifically during the acute and chronic phases of experimental inflammatory bowel disease, highlighting the importance of developing therapeutic strategies that align with the disease course.

Myosin light chain kinase-mediated epithelial barrier dysfunction as a potential pathogenic mechanism of afatinib-induced diarrheas: A study in human colonoid model

Diarrheas are an important adverse effect of afatinib, a tyrosine kinase inhibitor (TKI) anti-cancer drug, leading to mortality and morbidity in cancer patients with their pathophysiological mechanisms related to intestinal barrier dysfunctions being poorly understood. This study aimed to investigate the effect of afatinib on intestinal epithelial barrier integrity using a human colon-derived organoid model (colonoids). Afatinib (0.5 μM) significantly decreased the transepithelial electrical resistance (TEER) by ∼60% and increased apical-to-basolateral dextran flux by > 20 folds without causing apparent cytotoxicity in human colonoids. The delocalization of zonula occludens-1 (ZO-1) and a decrease in mRNA and protein expression of claudin-4 and ZO-1 were also observed in the afatinib-treated human colonoids. Afatinib induced nuclear translocation of nuclear factor kappa B (NF-κB) as well as mRNA and protein expression of NF-κB targets including tumor necrosis factor (TNF)-alpha, interleukin-8 (IL-8), and inducible nitric oxide synthase (iNOS) indicating the initiation of the NF-κB-mediated epithelial inflammatory responses. Interestingly, afatinib induced mRNA and protein expression of myosin light chain (MLC) kinase (MLCK) and MLC phosphorylation, a known inducer of intestinal epithelial barrier disruption. Treatment with iNOS inhibitor (1400W) or MLCK inhibitor (ML-7) reversed the effect of afatinib on mRNA expressions of ZO-1 and claudin-4, and TEER. Collectively, our results indicate that afatinib induces intestinal epithelial barrier dysfunction via mechanisms involving NF-κB-iNOS-MLCK pathways. This finding may pave the way for developing therapeutic strategies to reduce adverse effects and enhance efficacy of TKI in cancer patients.

Neuro-Mesenchymal Interaction Mediated by a β2-Adrenergic Nerve Growth Factor Feedforward Loop Promotes Colorectal Cancer Progression

SIGNIFICANCE

Our work demonstrates that the bidirectional interplay between sympathetic nerves and NGF-expressing CAFs drives colorectal tumorigenesis. This study also offers novel mechanistic insights into catecholamine action in colorectal cancer. Inhibiting the neuro-mesenchymal interaction by TRK blockade could be a potential strategy for treating colorectal cancer.

Alternative Splicing at the Crossroad of Inflammatory Bowel Diseases and Colitis-Associated Colon Cancer

The risk of developing colorectal cancer (CRC) is increased in ulcerative colitis patients compared to the general population. This increased risk results from the state of chronic inflammation, a well-known tumour-promoting condition. This review explores the pathologic and molecular characteristics of colitis-associated colon cancer (CAC), emphasizing the distinct features from sporadic CRC. We focus on the key signalling pathways involved in the transition to CAC, highlighting the emerging role of alternative splicing in these processes, namely on how inflammation-induced alternative splicing can significantly contribute to the increased CRC risk observed among UC patients. This review calls for more transcriptomic studies to elucidate the molecular mechanisms through which inflammation-induced alternative splicing drives CAC pathogenesis. A better understanding of these splicing events is crucial as they may reveal novel biomarkers for disease progression and have the potential to target changes in alternative splicing as a therapeutic strategy.

NAC regulates metabolism and cell fate in intestinal stem cells

Intestinal stem cells (ISCs) face the challenge of integrating metabolic demands with unique regenerative functions. Studies have shown an intricate interplay between metabolism and stem cell capacity; however, it is still not understood how this process is regulated. Combining ribosome profiling and CRISPR screening in intestinal organoids, we identify the nascent polypeptide-associated complex (NAC) as a key mediator of this process. Our findings suggest that NAC is responsible for relocalizing ribosomes to the mitochondria and regulating ISC metabolism. Upon NAC inhibition, intestinal cells show decreased import of mitochondrial proteins, which are needed for oxidative phosphorylation, and, consequently, enable the cell to maintain a stem cell identity. Furthermore, we show that overexpression of NACα is sufficient to drive mitochondrial respiration and promote ISC identity. Ultimately, our results reveal the pivotal role of NAC in regulating ribosome localization, mitochondrial metabolism, and ISC function, providing insights into the potential mechanism behind it.

Impact of different feed intake levels on intestinal morphology and epithelial cell differentiation in piglets

This study aimed to investigate the effect of feed intake levels on the development of intestinal morphology and epithelial cell differentiation in piglets. Sixty-four 35-d-old healthy weaned piglets ([Large White × Landrace] × Duroc) with an initial weight (6.93 ± 0.12 kg) were randomly divided into 4 groups (100%, 80%, 40%, and 20% feed intake) with 8 replicates of 2 pigs each. Samples were collected on days 3 and 7. The results revealed that with an increase in feed restriction degree and time, the body weight and organ index of piglets significantly decreased, and the villus height (VH) and crypt depth of the duodenum, jejunum, and ileum also decreased linearly (P < 0.05). After 3 d of feed restriction, jejunal ki67, endocrine cells, goblet cells, and villus endocrine/VH all decreased linearly, but the villus cup/VH ratio increased linearly, and the 40% and 20% were significantly higher than those of the 100% and 80% (P < 0.05). There was also a linear decrease in jejunal ki67, endocrine cells, goblet cells, and villous endocrine/VH in piglets fed 7 d of food restriction; however, the villus goblet cells/VH ratio in the 20% was significantly higher than that in the 40% group and was not different from that in the 80% (P < 0.05). During 3 d of feed restriction, the expression of jejunal differentiation marker genes showed a linear decreasing trend (P < 0.05) but increased linearly after 7 d of feed restriction. The expression levels of interleukin17 (IL-17) and IL-22 also increased linearly (P < 0.05). Kyoto Encyclopedia of Genes and Genomes and gene set enrichment analysis analyses indicated that the PPAR signaling pathway, ECM-receptor interaction, and Th1, Th2, and Th17 cell differentiation were significantly enriched in these processes. real-time quantitative polymerase chain reaction demonstrated that both PPAR and ECM-receptor interactions were significantly activated during 7 d of feeding restriction (P < 0.05). The results showed that with an increase in feed restriction intensity and time, the intestinal morphology and epithelial cell proliferation and differentiation were significantly reduced, except for the goblet cells. This phenomenon is related to the regulation of intestinal differentiation by IL-17 and IL-22 secreted by the Th cells.

Long-range organization of intestinal 2D-crypts using exogenous Wnt3a micropatterning

Intestinal epithelial cells are segregated into proliferative crypts and differentiated regions. This organization relies on specific signals, including Wnt3a, which regulates cell proliferation within crypts, and Eph/Ephrin, which dictates cell positioning along the crypt-villus axis. However, studying how the spatial distributions of these signals influences crypt-villus organization is challenging both in vitro and in vivo. Here we show that micropatterns of Wnt3a can govern the size, shape and long-range organization of crypts in vitro. By adjusting the spacing between Wnt3a ligand patterns at the microscale over large surfaces, we override endogenous Wnt3a to precisely control the distribution and long-range order of crypt-like regions in primary epithelial monolayers. Additionally, an agent-based model integrating Wnt3a/BMP feedback and Eph/Ephrin repulsion effectively replicates experimental tissue compartmentalization, crypt size, shape, and organization. This combined experimental and computational approach offers a framework to study how signaling pathways help organize intestinal epithelial tissue.

Advancing therapeutic strategies for graft-versus-host disease by targeting gut microbiome dynamics in allogeneic hematopoietic stem cell transplantation: current evidence and future directions

Hematopoietic stem cell transplantation (HSCT) is a highly effective therapy for malignant blood illnesses that pose a high risk, as well as diseases that are at risk due to other variables, such as genetics. However, the prevalence of graft-versus-host disease (GVHD) has impeded its widespread use. Ensuring the stability of microbial varieties and associated metabolites is crucial for supporting metabolic processes, preventing pathogen intrusion, and modulating the immune system. Consequently, it significantly affects the overall well-being and susceptibility of the host to disease. Patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) may experience a disruption in the balance between the immune system and gut bacteria when treated with medicines and foreign cells. This can lead to secondary intestinal inflammation and GVHD. Thus, GM is both a reliable indicator of post-transplant mortality and a means of enhancing GVHD prevention and treatment after allo-HSCT. This can be achieved through various strategies, including nutritional support, probiotics, selective use of antibiotics, and fecal microbiota transplantation (FMT) to target gut microbes. This review examines research advancements and the practical use of intestinal bacteria in GVHD following allo-HSCT. These findings may offer novel insights into the prevention and treatment of GVHD after allo-HSCT.

Liver X receptor unlinks intestinal regeneration and tumorigenesis

Uncontrolled regeneration leads to neoplastic transformation1-3. The intestinal epithelium requires precise regulation during continuous homeostatic and damage-induced tissue renewal to prevent neoplastic transformation, suggesting that pathways unlinking tumour growth from regenerative processes must exist. Here, by mining RNA-sequencing datasets from two intestinal damage models4,5 and using pharmacological, transcriptomics and genetic tools, we identified liver X receptor (LXR) pathway activation as a tissue adaptation to damage that reciprocally regulates intestinal regeneration and tumorigenesis. Using single-cell RNA sequencing, intestinal organoids, and gain- and loss-of-function experiments, we demonstrate that LXR activation in intestinal epithelial cells induces amphiregulin (Areg), enhancing regenerative responses. This response is coordinated by the LXR-ligand-producing enzyme CYP27A1, which was upregulated in damaged intestinal crypt niches. Deletion of Cyp27a1 impaired intestinal regeneration, which was rescued by exogenous LXR agonists. Notably, in tumour models, Cyp27a1 deficiency led to increased tumour growth, whereas LXR activation elicited anti-tumour responses dependent on adaptive immunity. Consistently, human colorectal cancer specimens exhibited reduced levels of CYP27A1, LXR target genes, and B and CD8 T cell gene signatures. We therefore identify an epithelial adaptation mechanism to damage, whereby LXR functions as a rheostat, promoting tissue repair while limiting tumorigenesis.

Safety, clinical activity, pharmacodynamics, and pharmacokinetics of IMU-856, a SIRT6 modulator, in coeliac disease: a first-in-human, randomised, double-blind, placebo-controlled, phase 1 trial

BACKGROUND

IMU-856 is an orally available and systemically acting small molecule modulator of sirtuin 6 (SIRT6), a protein that serves as a transcriptional regulator of bowel epithelium regeneration. We aimed to evaluate the safety, clinical activity, pharmacodynamics, and pharmacokinetics of IMU-856 in healthy participants and in patients with coeliac disease.

METHODS

This study reports the results from a completed first-in-human, three-part, double-blind, randomised, placebo-controlled, clinical trial of IMU-856 in healthy participants and patients with coeliac disease done in Australia and New Zealand. In part A, healthy participants were enrolled in six cohorts and randomly assigned (3:1) using a block randomisation algorithm to receive single ascending doses of IMU-856 ranging from 10 mg to 160 mg or matching placebo. Based on the results from part A, three doses were selected for part B to evaluate the safety, tolerability, and pharmacokinetics of IMU-856 once daily for 14 days using the same randomisation algorithm. Part C enrolled patients with well controlled coeliac disease. Participants were centrally randomised 1:1:1 using an interactive web response system to receive either low dose or high dose of IMU-856 or placebo once daily for 28 days that included a 15-day gluten challenge starting on day 14. The primary objective was safety and tolerability of IMU-856. Safety analyses were done on all patients who received at least one dose of the study drug. The trial is registered with the ANZCTR registry (ACTRN12620000901909).

FINDINGS

Between July 27, 2020, and Oct 28, 2022, 71 healthy participants were enrolled in part A and B and assigned to either placebo (n=19) or IMU-856 (n=52). In part A and B, the IMU-856 doses were 10 mg (n=6), 20 mg (n=6), 40 mg (n=13), 80 mg (n=12), 120 mg (n=4), 160 mg (n=11). 43 patients with coeliac disease were enrolled in part C and assigned to either placebo (n=14), IMU-856 80 mg (n=14), or IMU-856 160 mg (n=15). Treatment-emergent adverse events (TEAEs) occurred in 24 (73%) of 33 participants in part A and 15 (79%) of 19 participants in part B receiving any dose of IMU-856 compared with six (50%) of 12 participants in part A and five (71%) of seven participants in part B with placebo. TEAEs were mainly mild in severity. In part C, TEAEs occured in 26 (90%) of 29 patients on any dose of IMU-856 and ten (71%) of 14 receiving placebo; the most common TEAEs with any dose of IMU-856 by preferred term were headache (13 [45%] of 29), nausea (nine [31%]), diarrhoea (eight [28%]), and abdominal distension (seven [24%]). Two serious adverse events occurred with IMU-856 treatment (one in part B [bacterial myocarditis] and one in part C [biliary colic]), both of which were unrelated to IMU-856. No dose-limiting toxicities, systematic safety laboratory changes, or deaths occurred during the study. In part C, mean decrease in villous height was -20·9 μm (SD 34·8) among patients who received IMU-856 80 mg, -22·5 μm (51·1) among those who received IMU-856 160 mg, and -60·3 μm (52·2) among those who received placebo.

INTERPRETATION

The favourable safety profile, along with preliminary activity, suggests that IMU-856 should be studied in future trials of coeliac disease.

FUNDING

Immunic Australia.

Licensing and niche competition in spermatogenesis: mathematical models suggest complementary regulation of tissue maintenance

To maintain and regenerate adult tissues after injury, division and differentiation of tissue-resident stem cells must be precisely regulated. It remains elusive which regulatory strategies prevent exhaustion or overgrowth of the stem cell pool, whether there is coordination between multiple mechanisms, and how to detect them from snapshots. In Drosophila testes, somatic stem cells transition to a state that licenses them to differentiate, but remain capable of returning to the niche and resuming cell division. Here, we build stochastic mathematical models for the somatic stem cell population to investigate how licensing contributes to homeostasis. We find that licensing, in combination with differentiation occurring in pairs, is sufficient to maintain homeostasis and prevent stem cell extinction from stochastic fluctuations. Experimental data have shown that stem cells are competing for niche access, and our mathematical models demonstrate that this contributes to the reduction in the variability of stem cell numbers but does not prevent extinction. Hence, a combination of both regulation strategies, licensing with pairwise differentiation and competition for niche access, may be needed to reduce variability and prevent extinction simultaneously.

Advanced Endoscopic Imaging to Predict Clinical Outcomes in Inflammatory Bowel Disease

Advanced endoscopic imaging including high-definition endoscopy, confocal laser endomicroscopy (CLE) and endocytoscopy (EC) serve as an adjunct to predict clinical outcomes in inflammatory bowel disease (IBD). CLE can identify gut barrier dysfunction which correlates with disease behavior and long-term disease outcome. EC allows the assessment of histologic activity. Future controlled studies are warranted to define a definite role of these novel technologies in the management of patients with IBD.

Dietary and metabolic effects on intestinal stem cells in health and disease

Diet and nutritional metabolites exhibit wide-ranging effects on health and disease partly by altering tissue composition and function. With rapidly rising rates of obesity, there is particular interest in how obesogenic diets influence tissue homeostasis and risk of tumorigenesis; epidemiologically, these diets have a positive correlation with various cancers, including colorectal cancer. The gastrointestinal tract is a highly specialized, continuously renewing tissue with a fundamental role in nutrient uptake and is, in turn, influenced by diet composition and host metabolic state. Intestinal stem cells are found at the base of the intestinal crypt and can generate all mature lineages that comprise the intestinal epithelium and are uniquely influenced by host diet, metabolic by-products and energy dynamics. Similarly, tumour growth and metabolism can also be shaped by nutrient availability and host diet. In this Review, we discuss how different diets and metabolic changes influence intestinal stem cells in homeostatic and pathological conditions, as well as tumorigenesis. We also discuss how dietary changes and composition affect the intestinal epithelium and its surrounding microenvironment.

Curcumin alleviated dextran sulfate sodium-induced ulcerative colitis via inhibition of the Wnt/β-catenin signaling pathway and regulation of the differentiation of intestinal stem cells

In this study, we investigated the regulatory role of curcumin in the differentiation of intestinal stem cells (ISCs) in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) model mice and explored whether this effect was mediated by the Wnt/β-catenin signaling pathway. We conducted experiments in DSS-induced UC model mice to observe changes in intestinal morphology through HE staining and detect the expression of key proteins in the Wnt/β-catenin signaling pathway. According to these findings, curcumin was found to have a significant impact on the differentiation of ISCs. These results indicated that curcumin inhibited the Wnt/β-catenin signaling pathway and restored ISC differentiation. The effects of curcumin on the Wnt/β-catenin signaling pathway were further confirmed using Wnt/β-catenin agonists. These findings provide a new perspective for understanding the behavior of ISCs in the context of inflammation and offer new insights into the development of novel therapeutic strategies and drugs for UC.

Type III interferons induce pyroptosis in gut epithelial cells and impair mucosal repair

Tissue damage and repair are hallmarks of inflammation. Despite a wealth of information on the mechanisms that govern tissue damage, mechanistic insight into how inflammation affects repair is lacking. Here, we investigated how interferons influence tissue repair after damage to the intestinal mucosa. We found that type III, not type I or type II, interferons delay epithelial cell regeneration by inducing the upregulation of Z-DNA-binding protein 1 (ZBP1). Z-nucleic acids formed following intestinal damage are sensed by ZBP1, leading to caspase-8 activation and the cleavage of gasdermin C (GSDMC). Cleaved GSDMC drives epithelial cell death by pyroptosis and delays repair of the large or small intestine after colitis or irradiation, respectively. The type III interferon/ZBP1/caspase-8/GSDMC axis is also active in patients with inflammatory bowel disease (IBD). Our findings highlight the capacity of type III interferons to delay gut repair, which has implications for IBD patients or individuals exposed to radiation therapies.

Mesenchymal GDNF promotes intestinal enterochromaffin cell differentiation

Enteroendocrine cells (EECs) differentiate and mature to form functionally distinct populations upon migration along the intestinal crypt-villus axis, but how niche signals affect this process is poorly understood. Here, we identify expression of Glial cell line-derived neurotrophic factor (GDNF) in the intestinal subepithelial myofibroblasts (SEMFs), while the GDNF receptor RET was expressed in a subset of EECs, suggesting GDNF-mediated regulation. Indeed, GDNF-RET signaling induced increased expression of EEC genes including Tph1, encoding for the rate-limiting enzyme for 5-hydroxytryptamine (5-HT, serotonin) biosynthesis, and increased the frequency of 5-HT+ enterochromaffin cells (ECs) in mouse organoid culture experiments and in vivo. Moreover, expression of the 5-HT receptor Htr4 was enriched in Lgr5+ intestinal stem cells (ISCs) and 5-HT reduced the ISC clonogenicity. In summary, our results show that GDNF-RET signaling regulate EEC differentiation, and suggest 5-HT as a potential niche factor regulating Lgr5+ ISC activity, with potential implications in intestinal regeneration.

ABL1‒YAP1 axis in intestinal stem cell activated by deoxycholic acid contributes to hepatic steatosis

BACKGROUND

Yes-associated protein 1 (YAP1) regulates the survival, proliferation, and stemness of cells, and contributes to the development of metabolic dysfunction associated fatty liver disease (MAFLD). However, the regulatory role of intestinal YAP1 in MAFLD still remains unclear.

METHODS

Terminal ileal specimens were used to compare intestinal YAP1 activation in patients with and without MAFLD. Mice targeted for knocking out YAP1 in the intestinal epithelium were fed a high-fat diet (HFD) for 8 consecutive weeks. In a separate group, the mice were fed an HFD supplemented with the bile acid binder cholestyramine (CHO) or a low-fat diet with deoxycholic acid (DCA). Immunofluorescence, Immunohistochemistry, Western blot, RT-qPCR, ELISA, 16S rDNA sequencing, tissue and enteroid culture techniques were used to evaluate the effects of an HFD or DCA on the gut‒liver axis in mice or humans.

RESULTS

Intestinal YAP1 was activated in both humans with MAFLD and mice fed an HFD. In in vivo studies, YAP1 knockout in intestinal epithelial cells of mice alleviated the hepatic steatosis induced by an HFD, and mitigated the adverse effects of HFD on the gut‒liver axis, including the upregulation of lipopolysaccharide (LPS) and inflammation levels, enrichment of intestinal Gram-negative bacteria, and inhibition of intestinal stem cell (ISC) differentiation into the goblet and Paneth cells. High-fat feeding (HFF) produced high concentrations of DCA. The consumption of DCA mimics these HFF-induced changes, and is accompanied by the activation of Abelson tyrosine-protein kinase 1 (ABL1) and its direct substrate, YAP1, in the terminal ileum. In vitro studies further confirmed that DCA upregulated the tyrosine phosphorylation of YAP1Y357 in ISC by activating ABL1, which inhibited the differentiation of ISCs into secretory cells.

CONCLUSIONS

Our findings reveal that the activation of the ABL1‒YAP1 axis in ISCs by DCA contributes to hepatic steatosis through the gut‒liver axis, which may provide a potential intestinal therapeutic target for MAFLD.

A hybrid epithelial-mesenchymal transition program enables basal epithelial cells to bypass stress-induced stasis and contributes to a metaplastic breast cancer progenitor state

BACKGROUND

Human mammary epithelial cell (HMEC) cultures encounter a stress-associated barrier termed stasis, during which most cells adopt a senescence-like phenotype. From these cultures, rare variants emerge from the basal epithelial population, re-initiating growth. Variants exhibit pre-malignant properties, including an aberrant epigenetic program that enables continued proliferation and acquisition of genetic changes. Following oncogenic transformation, variants produce tumors that recapitulate the histopathological characteristics of metaplastic breast cancer (MBC), a rare and aggressive subtype marked by the differentiation of neoplastic epithelium into squamous and mesenchymal elements.

METHODS

Using a serum-free HMEC culture system, we probed the capacity for phenotypic plasticity inherent to basal epithelial cell populations from human breast tissue as they navigated stasis and emerged as variant populations.

RESULTS

We observed robust activation of a TGF-β-dependent epithelial-mesenchymal transition (EMT) program in basal epithelial cells during stasis, followed by subsequent attenuation of this program in emerging variants. Inhibition of the TGF-β pathway or depleting the EMT regulators Snail or Slug allowed basal epithelial cells to collectively bypass stasis, demonstrating that cellular dysfunction and arrest resulting from TGF-β and EMT activation are central to this in vitro barrier. The spontaneous emergence of variants from stasis cultures was associated with a restricted EMT trajectory, characterized by the stabilization of hybrid EMT states associated with greater proliferative capacity, rather than progressing to a complete mesenchymal state characterized by irreversible growth arrest. Epigenetic mechanisms, which contributed to the dysregulated growth control characteristic of the variant phenotype, also contributed to the stability of the hybrid EMT program in variants. By overcoming the cellular dysfunction and growth arrest resulting from TGF-β and complete EMT, variants exhibited a higher oncogenic transformation efficiency compared to pre-stasis basal epithelial cells. Inhibiting the TGF-β pathway prior to stasis significantly reduced EMT in the basal epithelial population, alleviated selective pressure driving variant emergence, and also enhanced oncogenic transformation efficiency, resulting in tumors with markedly diminished metaplastic differentiation.

CONCLUSIONS

This study reveals how an epigenetic program governs basal epithelial cell fate decisions and contributes to the development of MBC progenitors by restricting access to terminal mesenchymal states that induce growth arrest and, instead, favoring hybrid EMT states with enhanced tumorigenic potential.