Mucosal Regeneration Research Articles

Protective effect of Dulaglutide, a GLP1 agonist, on acetic acid-induced ulcerative colitis in rats: involvement of GLP-1, TFF-3, and TGF-β/PI3K/NF-κB signaling pathway.

A chronic inflammatory condition of the colon called ulcerative colitis (UC) is characterized by mucosal surface irritation that extends from the rectum to the near proximal colon portions. The rationale of this work was to conclude if dulaglutide (Dula) could protect rats from developing colitis caused by exposure to acetic acid (AA). Rats were randomly divided into seven groups (each with eight rats): Normal control, Dula control, AA (received 2 milliliters of 3% v/v AA through the rectum), Sulfasalazine (SLZ); given SLZ (100 mg/kg) orally from day 11 to day 21 then AA intrarectally on day 22 and Dula groups ( pretreated with 50, 100 or 150 μg/kg subcutaneous injection of Dula - once weekly for three weeks and AA on day 22 to induce ulcerative colitis, colon tissues and blood samples were taken on day 23. By generating colonic histological deviations such as inflammatory processes, goblet cell death, glandular hyperplasia, and mucosa ulcers, Dula dropped AA-induced colitis. Additionally, these modifications diminished blood lactate dehydrogenase (LDH), C-reactive protein (CRP), colon weight, and the weight/length ratio of the colon. In addition, Dula decreased the oxidative stress biomarker malondialdehyde (MDA) and increased the antioxidant enzymes (total antioxidant capacity (TAC), reduced glutathione (GSH), and superoxide dismutase (SOD) concentrations). Dula also significantly reduced the expression of transforming growth factor-1 (TGF-β1), phosphatidylinositol-3-kinase (PI3K), protein kinase B (AKT) signaling pathway, and the inflammatory cytokines: nuclear factor kappa B (NF-κB), interleukin-6 (IL-6), and interferon-γ (IFN-γ) in colonic cellular structures. In addition, Dula enforced the levels of glucagon-like peptide-1 (GLP-1) and trefoil factor-3 (TFF-3) that were crucial to intestinal mucosa regeneration and healing of wounds. By modulating TGF-β1 in conjunction with other inflammatory pathways like PI3K/AKT and NF-κB, regulating the oxidant/antioxidant balance, and improving the integrity of the intestinal barrier, Dula prevented AA-induced colitis in rats.

Morphological changes in purulent wound defect of the oral mucosa when using a non-woven polymer membrane with vancomycin (experimental study)

Currently, the problem of effective treatment of purulent wounds of the oral mucosa is relevant, scientists are improving dressing materials, creating new coatings. The study tested for the first time a non-woven polymer membrane from a copolymer of vinylidene fluoride with tetrafluoroethylene with Vancomycin, presumably which will meet the requirements of an ideal dressing material. The purpose of the study is to determine the effect of a non-woven polymer membrane with Vancomycin on the regeneration of a purulent wound defect of the oral mucosa in experiment. 35 white Wistar rats were divided into three groups: first group (n = 15), in which the wound defect was left open according to the standard procedure of the wound process in the oral cavity; second group (n = 15), in which the wound defect was covered with a non-woven polymer membrane with Vancomycin; third group (served as control group), in which the rats had intact oral mucosa (n = 5). Tissue samples were collected from the area of the purulent wound on the 3rd, 7th and 14th days of the study and histological sections were prepared using a standard procedure. The indicators were calculated using the AxioVision SE64 Rel program. 4.9.1: area of loose fibrous connective tissue (%), cellular infiltration (%), granulation tissue (%).The statistical analysis of the obtained data was performed using Mann–Whitney and Wilcoxon tests in Statistica 8.0 (StatSoft, USA) software. Differences were considered statistically significant at p 0.05. It has been established that the non-woven polymer membrane from a copolymer of vinylidene fluoride with tetrafluoroethylene with Vancomycin has a beneficial effect on the regeneration of the oral mucosa in the postoperative period and reduces scar changes in the later stages of healing.

Copper hydrogen phosphate nanosheets functionalized hydrogel with tissue adhesive, antibacterial, and angiogenic capabilities for tracheal mucosal regeneration

Timely and effective interventions after tracheal mucosal injury are lack in clinical practices, which elevate the risks of airway infection, tracheal cartilage deterioration, and even asphyxiated death. Herein, we proposed a biomaterial-based strategy for the repair of injured tracheal mucosal based on a copper hydrogen phosphate nanosheets (CuHP NSs) functionalized commercial hydrogel (polyethylene glycol disuccinimidyl succinate-human serum albumin, PH). Such CuHP/PH hydrogel achieved favorable injectability, stable gelation, and excellent adhesiveness within the tracheal lumen. Moreover, CuHP NSs within the CuHP/PH hydrogel effectively stimulate the proliferation and migration of endothelial/epithelial cells, enhancing angiogenesis and demonstrating excellent tissue regenerative potential. Additionally, it exhibited significant inhibitory effects on both bacteria and bacterial biofilms. More importantly, when injected injured site of tracheal mucosa under fiberoptic bronchoscopy guidance, our results demonstrated CuHP/PH hydrogel adhered tightly to the tracheal mucosa. The therapeutic effects of the CuHP/PH hydrogel were further confirmed, which significantly improved survival rates, vascular and mucosal regeneration, reduced occurrences of intraluminal infections, tracheal stenosis, and cartilage damage complications. This research presents an initial proposition outlining a strategy employing biomaterials to mitigate tracheal mucosal injury, offering novel perspectives on the treatment of mucosal injuries and other tracheal diseases.

Novel application of bone marrow mesenchymal stem cells combined with hepatocyte growth factor on subacute vocal fold wound healing

AbstractObjectivesVocal fold (VF) scar causes solemn vocal problems for patients with previous surgery or laryngeal injury. It is also a difficult management problem for clinicians since rare superior management methods are available at present. Previous research usually focuses on the acute period of VF wound repairing, with little attention on subacute period intervention. Bone marrow mesenchymal stem cells (BMMSCs) and hepatocyte growth factor (HGF) combinations that are applied to treat VF wounds are rarely reported. The current study investigated the effects of BMMSCs‐HGF application on the regeneration of the VF mucosa during the subacute period.MethodsA bilateral wound was generated by forceps in the VF of each New Zealand White rabbit. BMMSCs are based on the acellular dermal matrix as cell carriers. Various compounds (BMMSCs‐AMD complex with or without HGF) was injected into the wounded VF at 2‐ or 4‐weeks following injury. Animals were killed at 60 days postinjection. Imaging of excised larynges was performed with the transmission electron microscope (TEM), and Immunohistochemical (IHC) analysis was also conducted.ResultsCollectively, 18 rabbits accepted injury modeling, with two of them died before repairing intervention. IHC results indicated that type‐I collagen was significantly devalued in the cluster injected with BMMSCs‐HGF than simple application of BMMSCs. The results of TEM suggested that the BMMSCs‐HGF injection can significantly reduce the collagen score.ConclusionOur preliminary study suggests opening regenerative effects of intervention for VF subacute scaring, with BMMSCs‐HGF.

Effects of biocompatible piezoelectric membranes on the development of fibrosis associated with the oral mucosal wound regeneration

Effects of biocompatible piezoelectric membranes on the development of fibrosis associated with the oral mucosal wound regeneration

Evolutionary Analysis of the Mammalian IL-17 Cytokine Family Suggests Conserved Roles in Female Fertility.

The interleukin-17 (IL-17) family includes pro-inflammatory cytokines IL-17A-F with important roles in mucosal defence, barrier integrity and tissue regeneration. IL-17A can be dysregulated in fertility complications, including pre-eclampsia, endometriosis and miscarriage. Because mammalian subclasses (eutherian, metatherian, and prototherian) have different related reproductive strategies, IL-17 genes and proteins were investigated in the three mammalian classes to explore their involvement in female fertility. Gene and protein sequences for IL-17s are found in eutherian, metatherian and prototherian mammals. Through synteny and multiple sequence protein alignment, the relationships among mammalian IL-17s were inferred. Publicly available datasets of early pregnancy stages and female fertility in therian mammals were collected and analysed to retrieve information on IL-17 expression. Synteny mapping and phylogenetic analyses allowed the classification of mammalian IL-17 family orthologs of human IL-17. Despite differences in their primary amino acid sequence, metatherian and prototherian IL-17s share the same tertiary structure as human IL-17s, suggesting similar functions. The analysis of available datasets for female fertility in therian mammals shows up-regulation of IL-17A and IL-17D during placentation. IL-17B and IL-17D are also found to be over-expressed in human fertility complication datasets, such as endometriosis or recurrent implantation failure. The conservation of the IL-17 gene and protein across mammals suggests similar functions in all the analysed species. Despite significant differences, the upregulation of IL-17 expression is associated with the establishment of pregnancy in eutherian and metatherian mammals. The dysregulation of IL-17s in human reproductive disorders suggests them as a potential therapeutic target.

Gastroduodenal injury and repair mechanisms.

Although the mucosal barrier serves as a primary interface between the environment and host, little is known about the repair of acute, superficial lesions or deeper, persistent lesions that if not healed, can be the site of increased permeability to luminal antigens, inflammation, and/or neoplasia development. Studies on acute superficial lesions have been sparse in the past year, with more focus given to novel mechanisms of mucosal protection, and the way in which mature epithelial cells or committed stem cells dedifferentiate, reprogram, proliferate, and then regenerate the gastroduodenal mucosa after injury. For this, adenoviral therapy showed organ specific targeting with mRNA and protein expression of effectors to protect against mucosal injury and ulceration. A large database of plant-based agents known to protect against injury and ulceration was published, along with studies using plant-based compounds delivered with alginates, polysaccharide/gel floating rafts, or incorporated into nanoparticles or green carbon dots to improve targeting and retention at the ulcerated lesion. With RNA technology developing rapidly, particularly single-cell RNA sequencing, important and novel data was forthcoming on mucosal regeneration. In particular, the role of interleukin-17 hub proteins in mucosal healing was highlighted. The presence and role of injury reserve cells was determined, as was the composition of ligand gradients for cell differentiation in both stomach and duodenum. The role of amphiregulin in parietal cell differentiation from lineage-restricted stem cells and the Yap1 gene signature in metaplasia vs. healing ulcers were of particular importance. Additionally, studies unveiled the important role of mesenchymal stromal cells in differentiation and repair mechanisms, in Muse cells as an exciting new therapy for mucosal repair after injury, and the role of sympathetic neurons in activating the immune system to regulate mucosal repair mechanisms. Recent studies highlight novel mechanisms that promote mucosal regeneration after injury of the gastroduodenal mucosa.

Correction of Nitrosative Stress During Reparative Regeneration of the Nasal Cavity Mucosa in an Experimental

Introduction. Nitric oxide metabolites play an important role in prolongation of the inflammatory reaction, disorders of epithelial regeneration in diseases of the upper respiratory tract. One of the promising approaches to regulating the bioactivity of nitric oxide is the use of antioxidants.The objective of the study is to evaluate the effectiveness of antioxidant therapy for the correction of nitrosative stress during reparative regeneration of the nasal mucosa in an experiment.Methods. A preclinical randomized experimental study is conducted on 160 rats, divided into 4 groups. The control group (n = 40) consists of intact animals. Animals in experimental group 1 (n = 40) do not receive treatment aſter injury; in group 2 (n = 40) anti-inflammatory treatment is prescribed. The third group consists of laboratory rats (n = 40), which are additionally injected into the nasal cavity with an antioxidant — a 15 % solution of 1,1-dimethyl-3-oxobutylphosphonic acid dimethyl ester. On days 2, 5, 10, and 14 of observation, the concentration of nitrates and nitrites and C-reactive protein in the blood of animals are determined.Results. In group 3, aſter an increase in the level of nitric oxide metabolites on day 2 aſter injury on day 5, a significant (p < 0.05) decrease was noted in comparison with other groups, and by day 10— normalization of the indicator. An increase in the level of C-reactive protein in blood serum correlated with the concentration of nitric oxide metabolites.Discussion. The optimal therapeutic effect when taking antioxidants develops when administered in the first hours aſter injury to reduce the excessive formation of reactive nitrogen radicals. However, the duration of administration should not exceed 4–5 days to avoid a significant decrease in the level of nitric oxide metabolites and deterioration of mucosal regeneration.Conclusions. Assessment of nitric oxide metabolitesin the blood at different times aſter injury is an important marker of inflammatory activity. The use of antioxidants helps to reduce the concentration of active nitrogen radicals.

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

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

Aloe emodin promotes mucosal healing by modifying the differentiation fate of enteroendocrine cells via regulating cellular free fatty acid sensitivity

The proper differentiation and reorganization of the intestinal epithelial cell population is critical to mucosal regeneration post injury. Label retaining cells (LRCs) expressing SRY-box transcription factor 9 (SOX9) promote epithelial repair by replenishing LGR5+ intestinal stem cells (ISCs). While, LRCs are also considered precursor cells for enteroendocrine cells (EECs) which exacerbate mucosal damage in inflammatory bowel disease (IBD). The factors that determine LRC-EEC differentiation and the effect of intervening in LRC-EEC differentiation on IBD remain unclear. In this study, we investigated the effects of a natural anthraquinone called aloe emodin (derived from the Chinese herb rhubarb) on mucosal healing in IBD models. Our findings demonstrated that aloe emodin effectively interfered with the differentiation to EECs and preserved a higher number of SOX9+ LRCs, thereby promoting mucosal healing. Furthermore, we discovered that aloe emodin acted as an antagonist of free fatty acid receptors (FFAR1), suppressing the FFAR1-mediated Gβγ/serine/threonine-protein kinase (AKT) pathway and promoting the translocation of forkhead box protein O1 (FOXO1) into the nucleus, ultimately resulting in the intervention of differentiation fate. These findings reveal the effect of free fatty acid accessibility on EEC differentiation and introduce a strategy for promoting mucosal healing in IBD by regulating the FFAR1/AKT/FOXO1 signaling pathway.

Chitin-glucan improves important pathophysiological features of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is one of the most frequent and debilitating conditions leading to gastroenterological referrals. However, recommended treatments remain limited, yielding only limited therapeutic gains. Chitin-glucan (CG) is a novel dietary prebiotic classically used in humans at a dosage of 1.5-3.0 g/d and is considered a safe food ingredient by the European Food Safety Authority. To provide an alternative approach to managing patients with IBS, we performed preclinical molecular, cellular, and animal studies to evaluate the role of chitin-glucan in the main pathophysiological mechanisms involved in IBS. To evaluate the roles of CG in visceral analgesia, intestinal inflammation, barrier function, and to develop computational molecular models. Visceral pain was recorded through colorectal distension (CRD) in a model of long-lasting colon hypersensitivity induced by an intra-rectal administration of TNBS [15 milligrams (mg)/kilogram (kg)] in 33 Sprague-Dawley rats. Intracolonic pressure was regularly assessed during the 9 wk-experiment (weeks 0, 3, 5, and 7) in animals receiving CG (n = 14) at a human equivalent dose (HED) of 1.5 g/d or 3.0 g/d and compared to negative control (tap water, n = 11) and positive control (phloroglucinol at 1.5 g/d HED, n = 8) groups. The anti-inflammatory effect of CG was evaluated using clinical and histological scores in 30 C57bl6 male mice with colitis induced by dextran sodium sulfate (DSS) administered in their drinking water during 14 d. HT-29 cells under basal conditions and after stimulation with lipopolysaccharide (LPS) were treated with CG to evaluate changes in pathways related to analgesia (µ-opioid receptor (MOR), cannabinoid receptor 2 (CB2), peroxisome proliferator-activated receptor alpha, inflammation [interleukin (IL)-10, IL-1b, and IL-8] and barrier function [mucin 2-5AC, claudin-2, zonula occludens (ZO)-1, ZO-2] using the real-time PCR method. Molecular modelling of CG, LPS, lipoteichoic acid (LTA), and phospholipomannan (PLM) was developed, and the ability of CG to chelate microbial pathogenic lipids was evaluated by docking and molecular dynamics simulations. Data were expressed as the mean ± SEM. Daily CG orally-administered to rats or mice was well tolerated without including diarrhea, visceral hypersensitivity, or inflammation, as evaluated at histological and molecular levels. In a model of CRD, CG at a dosage of 3 g/d HED significantly decreased visceral pain perception by 14% after 2 wk of administration (P < 0.01) and reduced inflammation intensity by 50%, resulting in complete regeneration of the colonic mucosa in mice with DSS-induced colitis. To better reproduce the characteristics of visceral pain in patients with IBS, we then measured the therapeutic impact of CG in rats with TNBS-induced inflammation to long-lasting visceral hypersensitivity. CG at a dosage of 1.5 g/d HED decreased visceral pain perception by 20% five weeks after colitis induction (P < 0.01). When the CG dosage was increased to 3.0 g/d HED, this analgesic effect surpassed that of the spasmolytic agent phloroglucinol, manifesting more rapidly within 3 wk and leading to a 50% inhibition of pain perception (P < 0.0001). The underlying molecular mechanisms contributing to these analgesic and anti-inflammatory effects of CG involved, at least in part, a significant induction of MOR, CB2 receptor, and IL-10, as well as a significant decrease in pro-inflammatory cytokines IL-1b and IL-8. CG also significantly upregulated barrier-related genes including muc5AC, claudin-2, and ZO-2. Molecular modelling of CG revealed a new property of the molecule as a chelator of microbial pathogenic lipids, sequestering gram-negative LPS and gram-positive LTA bacterial toxins, as well as PLM in fungi at the lowesr energy conformations. CG decreased visceral perception and intestinal inflammation through master gene regulation and direct binding of microbial products, suggesting that CG may constitute a new therapeutic strategy for patients with IBS or IBS-like symptoms.

Piezoelectric and Dielectric Electrospun Fluoropolymer Membranes for Oral Mucosa Regeneration: A Comparative Study.

Wound healing of the oral mucosa is an urgent problem in modern dental surgical practice. This research article presents and compares the findings of the investigations of the structural, physicochemical, and biological characteristics of two types of polymeric membranes used for the regeneration of oral mucosa. The membranes were prepared from poly(tetrafluoroethylene) (PTFE) and a copolymer of vinylidene fluoride and tetrafluoroethylene (VDF-TeFE) and analyzed via scanning electron microscopy, atomic force microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. Investigation results obtained indicate that both types of membranes are composed of thin fibers: (0.57 ± 0.25) μm for PTFE membranes and (0.43 ± 0.14) μm for VDF-TeFE membranes. Moreover, the fibers of VDF-TeFE membranes exhibit distinct piezoelectric properties, which are confirmed by piezoresponse force microscopy and X-ray diffraction. Both types of membranes are hydrophobic: (139.7 ± 2.5)° for PTFE membranes and (133.5 ± 2.0)° for VDF-TeFE membranes. In vitro assays verify that both membrane types did not affect the growth and division of mice fibroblasts of the 3T3-L1 cell line, with a cell viability in the range of 88-101%. Finally, in vivo comparative experiments carried out using Wistar rats demonstrate that the piezoelectric VDF-TeFE membranes have a high ability to regenerate oral mucosa.

Cytological examination of the nasal mucosa in rhinological patients in the postoperative period

Introduction. Cytological examination of the nasal mucosa allows one to assess the activity of inflammation and the quality of the reparative regeneration process in the postoperative period in rhinological patients. The aim of the study is to diagnose the state of regeneration of the nasal mucosa in rhinological patients in the postoperative period. Material and methods. The study examined 206 patients after septoplasty with vasotomy of the inferior turbinates for a deviated nasal septum and vasomotor rhinitis. The patients were divided into 5 groups depending on the prescribed local regeneration-correcting treatment. All patients underwent cytological examination to assess destructive changes in the epithelium according to the method of L.A. Matveeva. Patients were monitored before surgery, on the 5th, 10th, 21st, 30th, 42nd and 60th days of the postoperative period. Results. On the 5-10th day of the postoperative period, destructive processes predominated in rhinocytograms, and cell destruction indices were increased. From the 21st day, signs of proliferation were recorded, and the inflammatory reaction decreased. In the groups whose treatment regimens included reparants, rhinocytograms showed a more rapid decrease in cell destruction indices and a full restoration of cellular representation. A more pronounced reparative effect was detected in a solution of sodium deoxyribonuclease and dexpanthenol.&#x0D; Conclusion. In the postoperative period, rhinological patients after 2 months showed signs of impaired reparative regeneration. Local application of therapy restoring the nasal mucosa in the postoperative period led to cytoprotective, anti-inflammatory, earlier and more complete regenerative effects.

Abstract 262: Gastrin-dependent suppression of CCK2R+ antrum stem cells inhibits gastric atrophy and cancer initiation in C57BL/6 mice

Abstract Background The cholecystokin-2/gastrin receptor (CCK2R) is expressed by rare epithelial cells in the gastric antrum that are bone fide +4 gastric stem cells. CCK2R+ antral stem cells are relatively quiescent, divide asymmetrically, and lineage trace entire antral glands. Their stemness is sustained over time through gastrin/CCK2R signaling (Cell Stem Cell 26, 739-754, May 7, 2020). However, the role of gastrin/CCK2R signaling in antral stem cells during mucosal injury and regeneration has not been explored. Methods We generated CCK2R-CreERT2; Gastrin-BAC-DTR-P2A-TdTomato; Rosa26-ZsGreen mice in a C57BL/6 background. Hypogastrinemia was induced through diphtheria toxin-dependent ablation of antral G cells, while hypergastrinemia was achieved via Alzet pump gastrin infusion. Lineage tracing from antrum CCK2R+ stem cells was assessed quantitatively during homeostasis and also during injury in chronic H. pylori infection and MNU injury models. Results Our findings revealed that G cell ablation increased lineage tracing of CCK2R+ antral stem cells at day 14 and increased proliferation of antral epithelial cells (Ki67+ cells) (P&amp;lt;0.05). Moreover, sorted antrum CCK2R+ cells (24 hours post-tamoxifen induction) from DT-treated mice had increased organoids forming capacity and in vitro cell growth, consistent with an increase in active progenitors, while hypergastrinemia reduced their growth (P&amp;lt;0.05). Numb staining showed that G cell ablation led to increased symmetric division of CCK2R+ stem cells, while gastrin infusion maintained asymmetric division (P&amp;lt;0.05). In the chronic H. pylori infection model, after 3 months of infection, the G cell ablation group exhibited more severe gastric antral atrophy compared to controls. In the MNU injury model, after 18 weeks of injury, the G cell ablation group had a higher dysplasia score, with dysplastic lesions largely derived from CCK2R+ cells (P&amp;lt;0.05). In our ongoing studies of MNU injury, the G cell ablation group at 36 weeks showed significantly greater tumor number and size than the control groups. Single-cell RNA-seq data showed that G cell ablation led to the proliferation and expansion of CCK2R+ antral stem/progenitor cells. Conclusions In conclusion, while gastrin maintains long-term antral stem cell quiescence and self-renewal, hypogastrinemia over the short-term leads to expansion and proliferation of CCK2R+ antral stem cells, thus predisposing over the long-term to antral atrophy and cancer initiation. In C57BL/6 mice, hypergastrinemia appears to be a protective factor against antral cancer development. Citation Format: Biyun Zheng, Guodong Lian, Ermanno Malagola, Hiroki Kobayashi, Ruhong Tu, Feijing Wu, Jin Qian, Quin T. Waterbury, Yosuke Ochiai, Leah B Zamechek, Timothy C Wang. Gastrin-dependent suppression of CCK2R+ antrum stem cells inhibits gastric atrophy and cancer initiation in C57BL/6 mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 262.

Abstract 2125: The use of intestinal organoids as a preclinical screen to assess gastrointestinal (GI) toxicity and barrier integrity

Abstract Gastrointestinal (GI) toxicity is a common and often severe limiting factor in the development of antineoplastic drugs. Symptoms include diarrhoea, dehydration and ulceration which increase susceptibility to infection, partly due to damage of crypt and/or villus structures in the small intestine, impairing the barrier function. As novel targeted therapies are emerging, assessment of their potential GI toxicity remains crucial. Small intestinal (SI) organoids are 3D in vitro models of the epithelium which recapitulate the structure and function of the small intestine. We have further developed and validated the organoid model as a screening tool to predict GI toxicity and subsequent mucosal regeneration in four species: mouse, rat, dog and human. The culture conditions have been designed to mimic the stem cell niche and allow cell differentiation and proliferation to occur. All intestinal lineages were present in the organoids derived from each species and the epithelial hierarchy closely resembled that observed in vivo. The toxic effects of antineoplastic drugs on the organoids were assessed by quantification of the total cell viability upon treatment, coupled to morphometric analysis of the organoids (size, area, perimeter, and branching efficiency). Immunofluorescence and RNAseq can be used to identify the targeted cells and the toxicity mechanisms of the drugs. To further assess the effect of drugs on barrier integrity, we have developed transwell-grown cell monolayers derived from normal human small intestinal organoids. This model allows direct access to both apical and basal surfaces, which is not possible when using organoids where their geometry prevents access to the apical surface. The monolayer formation was followed by live imaging and Trans-Epithelial Electrical Resistance (TEER) measurements and treatments with toxic drugs were applied after TEER reached a plateau. The direct effect on barrier integrity was evaluated by TEER reduction, increased FITC-Dextran permeability and analysis of TJ proteins by immunofluorescence. Furthermore, effects on cell death were assessed by measuring the levels of Lactate Dehydrogenase (LDH) released into the medium by dying cells. In conclusion, our models provide an innovative in vitro solution to further study the toxic effects of drugs on the normal small intestine and to analyse direct effects on barrier integrity. The monolayer assay may also be useful for developing models of transient TJ impairment to improve the bioavailability of orally administered antineoplastic drugs. The model can be considered more representative of the normal intestine than transformed cell lines such as CaCo2. Citation Format: Valentina Ubertini, Sarah Hall, Frida Ponthan, James Wilson. The use of intestinal organoids as a preclinical screen to assess gastrointestinal (GI) toxicity and barrier integrity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2125.

Subepithelial Stromal Cells: Their Roles and Interactions with Intestinal Epithelial Cells during Gut Mucosal Homeostasis and Regeneration.

Intestinal epithelial cell activities during homeostasis and regeneration are well described, but their potential interactions with stromal cells remain unresolved. Exploring the functions of these heterogeneous intestinal mesenchymal stromal cells (iMSCs) remains challenging. This difficulty is due to the lack of specific markers for most functionally homogenous subpopulations. In recent years, however, novel clustering techniques such as single-cell RNA sequencing (scRNA-seq), fluorescence-activated cell sorting (FACS), confocal microscope, and computational remodeling of intestinal anatomy have helped identify and characterize some specific iMSC subsets. These methods help researchers learn more about the localization and functions of iMSC populations during intestinal morphogenic and homeostatic conditions. Consequently, it is imperative to understand the cellular pathways that regulate their activation and how they interact with surrounding cellular components, particularly during intestinal epithelial regeneration after mucosal injury. This review provides insights into the spatial distribution and functions of identified iMSC subtypes. It focuses on their involvement in intestinal morphogenesis, homeostasis, and regeneration. We reviewed related signaling mechanisms implicated during epithelial and subepithelial stromal cell crosstalk. Future research should focus on elucidating the molecular intermediates of these regulatory pathways to open a new frontier for potential therapeutic targets that can alleviate intestinal mucosa-related injuries.

Amphiregulin Switches Progenitor Cell Fate for Lineage Commitment During Gastric Mucosal Regeneration

Background & AimsIsthmic progenitors, tissue-specific stem cells in the stomach corpus, maintain mucosal homeostasis by balancing between proliferation and differentiation to gastric epithelial lineages. The progenitor cells rapidly adopt an active state in response to mucosal injury. However, it remains unclear how the isthmic progenitor cell niche is controlled during the regeneration of damaged epithelium. MethodsWe recapitulated tissue recovery process after acute mucosal injury in the mouse stomach. BrdU incorporation was utilized to trace newly generated cells during the injury and recovery phases. To define epithelial lineage commitment process during recovery, we performed single cell RNA-sequencing (scRNA-seq) on epithelial cells from the mouse stomachs. We validated the effects of amphiregulin (AREG) on mucosal recovery, utilizing recombinant AREG treatment or AREG deficient mice. ResultsWe determined that an EGFR ligand, AREG, can control progenitor cell lineage commitment. Based on the identification of lineage-committed subpopulations in the corpus epithelium through scRNA-seq and BrdU incorporation, we showed that isthmic progenitors mainly transition into short-lived surface cell lineages, but are less frequently committed to long-lived parietal cell lineages in homeostasis. However, mucosal regeneration after damage directs the lineage commitment of isthmic progenitors towards parietal cell lineages. During recovery, AREG treatment promoted repopulation with parietal cells, while suppressing surface cell commitment of progenitors. In contrast, TGF-alpha did not alter parietal cell regeneration, but did induce expansion of surface cell populations. AREG deficiency impairs parietal cell regeneration, but increases surface cell commitment. ConclusionsThese data demonstrate that different EGF receptor ligands can distinctly regulate isthmic progenitor-driven mucosal regeneration and lineage commitment.

A269 SEX-DEPENDENT EFFECT OF PANCREASTATIN INHIBITION ON COLON MUCOSAL INTEGRITY IN HOMEOSTATIC CONDITION

Abstract Background Sex bias in inflammatory bowel disease (IBD)-associated colorectal cancer (CRC) epidemiology is well known. Pancreastatin (PST), an epithelial cells-derived peptide overexpressed in IBD patients, regulates the endoplasmic reticulum (ER) and survival signalling involved in CRC. Pancreastatin inhibitor 8 (PSTi8), an inhibitor of PST, showed promising anti-inflammatory effects in IBD male mice model. However, no data exists regarding PST’s role in colon mucosal regeneration and epithelium maintenance. Aims Here, we investigated the impact of PSTi8 treatment on colonic epithelial cells in male and female mice under homeostatic conditions. Methods Male and female C57BL/6 mice were treated with PSTi8 (2.5mg/mL/kg, i.r.) or PBS for six days. Epithelial cells’ proliferation (Ki67) and differentiation (cytokeratin-20) were measured by immunofluorescence. Genetic markers for differentiated epithelial cells (goblet Muc2 and Tuft Dclk1), stem cells (fast-cycling Lgr5, reserve Hopx and fetal-like Ly6a), stem cell regulator (BMP4), epithelial cells lineage commitment (Atoh1, Hes1, Gfl1), ER activation (ATF6), and apoptosis (CHOP) were tested by qRT-PCR. Results PSTi8 treatment decreased epithelial cell proliferation in both sexes. The inhibition of PST lowered the differentiation of epithelial cells and mucus production and increased tuft cell gene expression in females but not in male mice. In females, PSTi8 treatment increased fast-cycling stem cells but lower reserve and fetal-like stem cells in both sexes. In addition, PST inhibition significantly downregulated BMP4, which regulates epithelial cell differentiation, in females while not altering its expression in males. In contrast, PSTi8 treatment significantly increased transcription factors regulating epithelial cells' self-renewal and lineage commitments Hes1 and GFI1 in females but decreased Atoh1 in both sexes. PST inhibition enhanced gene expression of ER stress molecules ATF6 and CHOP in female and ATF6 in male mice. CHOP remained unaltered by PST inhibition in males. Conclusions PSTi8 alters colonic epithelial regeneration, differentiation, and thus maintenance in a sex-dependent manner. Funding Agencies CIHRChildren’s Hospital Research Institute of Manitoba (CHRIM)/Research Manitoba

OP04 Endoscopic healing in paediatric IBD perpetuates a persistent signature characterized by pathogenic Th17 cells and tissue-associated molecular and microbial drivers of disease

Abstract Background Endoscopic healing (EH) is the major long-term treatment target for inflammatory bowel diseases (IBD) in adults and paediatric patients. However, EH may not represent disease clearance. Hence, risk of relapse remains high and treatment discontinuation after reaching EH often results in disease exacerbation. We aimed to identify persistent cellular, molecular and microbial drivers of IBD under EH and longitudinally collected endoscopic biopsies from paediatric patients for analysis of single T-cell and bulk transcriptomics as well as mucosa-associated microbiota. Methods We followed disease trajectories of paediatric IBD patients treated according to international guidelines and collected mucosal biopsies from the terminal ileum (TI) and sigmoid colon (SC) at baseline (T1) and after approximately 3-12 months (T2) to assess EH. Non-IBD controls showed no macroscopic or histologic signs of inflammation. Host RNA and bacterial DNA were simultaneously extracted from single biopsies for bulk RNA-seq, and 16S rRNA seq. A second biopsy was used for isolation of lamina propria mononuclear cells (LPMCs), followed by CD45+, CD3+ cell sorting and single T-cell analysis (10X Genomics). Data were quality controlled and integrated. Results 217 biopsies (135 simultaneous extraction of host RNA and bacterial DNA; 82 single T-cell analysis) from 32 paediatric IBD patients (mean age 13 ± 3.5 years, 21 Crohn’s disease [CD], 11 ulcerative colitis [UC]; T1 = 32, T2 = 32, T &amp;gt; 2 = 6) and 5 non-IBD controls were analysed. Time between T1 and T2 averages 40 ± 22 weeks. At baseline, 15 patients (14 CD, 1 UC) were newly diagnosed and 31/32 patients had active mucosal inflammation. Twenty-two patients (71%) achieved EH at T2 (SES-CED ≤2 and absence of ulcerations), mostly on anti-TNF therapy. One patient (EH at T1) experienced relapsing disease within 10 weeks after discontinuing medication. In the bulk RNA-seq, we identified 299 differential expressed genes (DEGs; corrected p-value &amp;lt;0.05, FC &amp;gt;2.0), such as DUOX2, SAA2-SAA4, FCGR3B and NOS2, that are associated with active IBD and remained upregulated in EH in contrast to non-IBD controls. In addition single cell analysis revealed an IBD-specific pathogenic Th17 cluster that continued to exist in EH and showed high correlation with top DEGs after data integration. 16S rRNA gene seq highlighted highly individual mucosa-associated bacterial profiles and a reduced α-diversity in active and EH compared to non-IBD controls. Conclusion A persisting IBD signature in EH reflects ongoing cellular, molecular and microbial activity in comparison to non-IBD controls despite EH and mucosal regeneration. These markers may provide targets for future or sequential therapies.

ECCO Grant Dissecting the role of S1PR1 modulator in the mucosal regeneration of Ulcerative Colitis

Abstract Background and Aims Ozanimod, a potent sphingosine 1-phosphate (S1P) 1/5 receptor agonist, first approved for the treatment of adults with moderately to severely active UC in the USA and in the EU, has showed promising results in terms of both tolerability and efficacy reducing inflammatory processes and inducing disease remission. The selectivity of Ozanimod for S1PR1 is 27 times that for S1PR5. Therefore, is plausible that the beneficial effects of Ozanimod are mediated by S1PR1, which is constitutively expressed not only by immune cells, but also by epithelial, endothelial, and stromal cells. However, its function on non-immune cells has been neglected. Based on preliminary data demonstrating a faster recovery of mucosal damage in mice with a conditional deletion of S1PR1 in the epithelia and endothelia compartments, our hypothesis is that the inactivation of S1PR1 not only inhibits immune cell trafficking, but also promotes tissue repair. Based on this background, the main objectives will be to exploit the Ozanimod effects during the process of mucosa healing, and to investigate the molecular pathways activated by Ozanimod on epithelial and endothelial cells. Methods Pre-clinical validation of Ozanimod, in vivo model of UC in association with conditional knockout mice for S1PR1 on epithelial and endothelial cells, stimulation of primary endothelial cells from UC patients and human induced pluripotent stem cell-derived intestinal organoids (iHOs) will be used to address our aims. Transcriptomics, functional assay, immune characterization, WB validation will be performed. Anticipated Impact In short and medium term, we will improve the knowledge on the role of S1PR1 in the processes of mucosal healing and identify the molecular pathways involved in the response to the mucosal damage mediated by the ozanimod in non-immune cells. The results of this study may improve the treatment options for UC patients.