Intestinal Regeneration Research Articles

DOP116 Preclinical characterization of IMU-856, an orally available epigenetic modulator of gut barrier function and regeneration

Abstract Background A dysfunctional intestinal mucosal barrier is a key pathophysiological hallmark and driver of a broad range of gastrointestinal diseases, including inflammatory bowel disease (IBD). To date, there are no adequate treatment strategies to ameliorate impaired barrier function. IMU-856 is an orally available and systemically acting small molecule modulator of sirtuin 6 (SIRT6), a histone/non-histone protein deacetylase and transcriptional regulator that targets the restoration of intestinal barrier function and regeneration of bowel epithelium without having any direct effect on the immune system. A double-blind, randomized, placebo-controlled phase 1/1b clinical trial of IMU-856 has been completed [1]. IMU-856 was shown to be safe and well-tolerated with a benign adverse event profile and pharmacokinetics that allow once-daily dosing. In Part C, a ‘proof of concept study’ in patients with celiac disease, IMU-856 demonstrated positive effects in four key dimensions of clinical outcome: protecting gut architecture, improving patients' symptoms severity, biomarker response and enhancing nutrient absorption. Methods In the presented preclinical studies, the target specificity and effects of IMU-856 on intestinal barrier function and regeneration were elucidated by in-vitro sirtuin activity assays, transepithelial electrical resistance (TEER) assays, dextran sulphate sodium (DSS)-induced colitis mouse models and gene expression analysis (bulk RNA sequencing). Moreover, potential immune suppressive effects of IMU-856 were assessed in stimulated human peripheral blood mononuclear cells (PBMCs). Multiple biomarkers related to health of intestinal epithelium and of enteric function were also assessed in preclinical studies and in the phase 1 trial. Results IMU-856 is a highly selective and potent modulator of SIRT6. In TEER assays, IMU-856 treatment enhanced the epithelial barrier recovery of Caco-2 monolayers after a destructive cytokine challenge and modulated tight junction protein levels. IMU-856 demonstrated activity in acute DSS-induced colitis models by reducing the severity of colitis, improving the mucosal architecture and preserving functional enterocytes (upregulation of enterocyte marker genes and the plasma biomarker citrulline). No effects of IMU-856 on T-cell proliferation and cytokine secretion (interferon-g (IFN-g)) were observed in human PBMCs. Conclusion IMU-856 data indicate restoration of intestinal barrier function and promotion of physiological mucosal regeneration without direct immunosuppressive effects and may therefore offer potential for the treatment of IBD and other gastrointestinal diseases with compromised barrier function.

DOP034 Intestinal stem cell dysfunction is driven by loss of HMGCS2-mediated ketogenic response in Ulcerative colitis and represents a novel therapeutic target

Abstract Background Intestinal stem cells (ISCs) continuously divide and differentiate into multiple lineages of enterocytes, a process that places high energy demands. Recent evidence implicates bioenergetic failure of ISCs with non-resolving inflammation in Ulcerative Colitis (UC)1. Methods In newly diagnosed, treatment-naïve UC patients, we characterized mitochondrial oxidative phosphorylation (OXPHOS) and metabolic proteins in epithelial and ISCs, performed single-cell RNA sequencing (scRNA-seq) to identify deregulated metabolic pathways, and assessed their biological relevance on intestinal regeneration with in-depth ex vivo metabolic platforms, including SCENITH (Single Cell Energetic Metabolism by Profiling Translation Inhibition). Results Single-cell quantitative immunofluorescence showed loss of mitochondrial OXPHOS Complex I and IV in UC (n=10/group; p<0.0001) and UC-derived organoids (n=20/group; p<0.0001), suggesting bioenergetic failure transmitted from ISCs to daughter epithelial cells. scRNA-seq of ISCs from active UC revealed significant ketogenesis pathway, downregulation, with HMGCS2 as the top downregulated gene (FC -2.76, p<0.0001). HMGCS2, the rate-limiting mitochondrial matrix ketogenesis enzyme, produces the ketone body βHB which, alongside providing metabolites for the TCA cycle, has important roles in stem cell fate-signalling2 (Figure 1). HGMCS2 expression was reduced along the crypt axis in active UC (n=20/group; p<0.001). Moreover, we find via colorimetric assay that colonic organoids produce and secrete βHB, and this is reduced in active UC (n= 5/group, p <0.001). βHB supplementation of UC organoids restores ISC function, measured via growth assay (n=5/group, p<0.05, Figure 2). Further scRNA-seq of βHB treated UC organoids revealed that βHB aids mitochondrial function and reduces cellular stress in ISCs, lowering expression of genes associated with stress and protein misfolding (HSPD1 and VDAC3), while increasing mitophagy (PINK1). Functionally, we confirm this by showing βHB restored OXPHOS capacity in UC organoids using SCENITH (n=3/group, p<0.05). βHB also reduced cellular and mitochondrial reactive oxygen species, measured via Cellrox (n=9/group, p<0.01). In UC organoids, fenofibrate (PPARα agonist), induced HMGCS2 expression (p<0.001) and βHB production (p<0.05). Finally, HMGCS2 protein expression significantly increased in responders to therapy with mucosal healing (n=4 paired samples, p<0.05). Conclusion We provide the first combined evidence of mitochondrial dysfunction and ketogenesis failure (‘primary’ and ‘backup’ energy failure) in UC. Crucially, restoring ketogenesis reverses the ISC pathogenic defect thus, opening a new ‘immuno-metabolic’ therapeutic approach in UC.

DOP012 Promising effects of IMU-856, an orally available epigenetic modulator of barrier regeneration - biomarker findings from a Phase 1 clinical study

Abstract Background A dysfunctional intestinal mucosal barrier is a key pathophysiological hallmark and driver of a broad range of gastrointestinal diseases including inflammatory bowel disease (IBD). To date, there are no adequate treatment strategies to ameliorate impaired barrier function. IMU-856 is an orally available and systemically acting small molecule modulator of sirtuin 6 (SIRT6), a histone/non-histone protein deacetylase which serves as a transcriptional regulator of intestinal barrier function and regeneration of bowel epithelium. In preclinical studies, IMU-856´s mechanism of action has been shown to avoid suppression of immune cells. This could present a new approach to treat intestinal barrier function associated diseases without the serious consequences associated with many immunosuppressive therapies. Methods This was a first-in-human, double-blind, randomized, placebo-controlled clinical trial of IMU-856 in healthy volunteers and patients with celiac disease. In the multiple ascending dose part, healthy human subjects were dosed once-daily for 14 consecutive days with IMU-856 at three different dose levels or placebo. Phase 1b was designed to assess safety and tolerability of IMU-856 at two different dose levels in patients with celiac disease during periods of gluten-free diet and a 15-day gluten challenge. Further objectives included pharmacokinetics and the assessment of histological changes. Biomarkers reflecting intestinal enterocyte function, intestinal integrity, nutrient absorption and general gut health were analyzed to assess the effect on the overall protection of gut architecture. Results IMU-856 was safe and well-tolerated with a benign adverse event profile and pharmacokinetics that allow once-daily dosing. There were no systematic clinically relevant findings relative to safety and tolerability. Treatment with IMU-856 improved the mass, metabolic function and health of intestinal enterocytes as measured by nutrient uptake as well as several biomarkers for intestinal function and integrity as well as general gut health [1]. Conclusion IMU-856 is a safe, highly selective and potent epigenetic modulator, showing signals of improving the intestinal barrier function in patients with celiac disease undergoing a gluten challenge.The positive effects of IMU-856 on various biomarkers for intestinal function, overall health and integrity in conjunction with the protection of gut architecture show that IMU-856 may offer extensive potential in other gastrointestinal diseases with compromised intestinal barrier function like IBD.

A feedback loop between Paxillin and Yorkie sustains Drosophila intestinal homeostasis and regeneration

Balanced self-renewal and differentiation of stem cells are crucial for maintaining tissue homeostasis, but the underlying mechanisms of this process remain poorly understood. Here, from an RNA interference (RNAi) screen in adult Drosophila intestinal stem cells (ISCs), we identify a factor, Pax, which is orthologous to mammalian PXN, coordinates the proliferation and differentiation of ISCs during both normal homeostasis and injury-induced midgut regeneration in Drosophila. Loss of Pax promotes ISC proliferation while suppressing its differentiation into absorptive enterocytes (ECs). Mechanistically, our findings demonstrate that Pax is a conserved target gene of the Hippo signaling pathway in both Drosophila and mammals. Subsequent investigations have revealed Pax interacts with Yki and enhances its cytoplasmic localization, thereby establishing a feedback regulatory mechanism that attenuates Yki activity and ultimately inhibits ISCs proliferation. Additionally, Pax induces the differentiation of ISCs into ECs by activating Notch expression, thus facilitating the differentiation process. Overall, our study highlights Pax as a pivotal component of the Hippo and Notch pathways in regulating midgut homeostasis, shedding light on this growth-related pathway in tissue maintenance and intestinal function.

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.

EGCG protects intestines of mice and pelvic cancer patients against radiation injury via the gut microbiota/D-tagatose/AMPK axis

Background and purposeRadiation-induced intestinal injury (RIII) compromises the clinical utility of pelvic radiotherapy (RT). We aimed to explore the protective effect and underlying mechanism of (−)-epigallocatechin-3-gallate (EGCG) on RIII. Materials and methodsWe evaluated the protective effect of EGCG on intestine in RIII mouse model and pelvic cancer patients, while explored the underlying mechanism through (1) 16S rRNA sequencing, (2) metabolomic profiles, (3) fresh sterile fecal filtrate (SFF) transplantation, and (4) transcriptome sequencing. ResultsEGCG efficiently prevented RIII in mouse, as reflected by improved survival, alleviated intestinal structure damage, promoted intestinal regeneration, and ameliorated gut microbiota dysbiosis. Prophylactic EGCG intervention reduced the severity of RIII in patients receiving pelvic RT. Mechanistically, the protective effect of EGCG could be transferred to other mice by SFF transplantation. EGCG enriched gut microbiota-derived metabolite D-tagatose, and oral administration of D-tagatose reproduced the radio-protective effect of EGCG via activating AMPK. ConclusionOral EGCG may be a promising strategy for preventing RIII clinically, and warrant further investigation in prospective randomized phase III trials.

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

BackgroundRadiotherapy for pelvic malignant tumors inevitably causes intestinal tissue damage. The regeneration of intestinal epithelium after radiation injury relies mainly on crypt fission. However, little is known about the regulatory mechanisms of crypt fission events.MethodsThe effects of WNT4 on crypt regeneration and the symmetry of crypt fission were examined using a mouse small intestinal organoid culture model. Three-dimensional (3D) reconstructed images of organoids were applied to assess the symmetry of crypt fission and Paneth cell localization upon manipulation of WNT4 expression. The effect of WNT4 on the expression of β-catenin target genes was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). The in vivo effect of WNT4 overexpression mediated by adeno-associated virus (AAV) on symmetric fission of crypt was investigated using a radiation-injured mouse model.ResultsWNT4 has a special function of promoting symmetric fission of small intestinal crypts, although it inhibits budding, stemness, and cell proliferation on organoids. WNT4 promotes the correct localization of Paneth cells in the crypt base by regulating the expression of EphB3, thereby promoting the symmetric fission of small intestinal crypts. WNT4 negatively regulates the canonical WNT/β-catenin signaling pathway, and it promotes symmetric crypt fission in a ROR2 receptor-dependent manner. Moreover, in patients and animal models of radiation-induced intestinal injury, we found that the regenerated crypts are irregular in size and shape, Paneth cells are mislocalized, and the expression of WNT4 is decreased while EphB3 is increased. Importantly, restoration of WNT4 expression mediated by AAV effectively promotes symmetric crypt fission and thus improves the regularity of regenerating crypts in mice with radiation-induced injury.ConclusionsOur study highlights the critical role of WNT4 in the regulation of crypt fission and provides WNT4 as a potential therapeutic target for radiation enteritis.Graphical

Intestinal stem cells in intestinal homeostasis and colorectal tumorigenesis.

Colorectal cancer (CRC), one of the most common tumors in the world, is generally proposed to be generated from intestinal stem cells (ISCs). Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5)-positive ISCs are located at the bottom of the crypt and harbor self-renewal and differentiation capacities, serving as the resource of all intestinal epithelial cells and CRC cells as well. Here we review recent progress in ISCs both in non-tumoral and tumoral contexts. We summarize the molecular mechanisms of ISC self-renewal, differentiation, and plasticity for intestinal homeostasis and regeneration. We also discuss the function of ISCs in colorectal tumorigenesis as cancer stem cells and summarize fate dynamic, competition, niche regulation, and remote environmental regulation of ISCs for CRC initiation and propagation.

Paneth Cells: Dispensable yet Irreplaceable for the Intestinal Stem Cell Niche.

Intestinal stem cells replenish the epithelium throughout life by continuously generating intestinal epithelial cell types, including absorptive enterocytes, and secretory goblet, endocrine, and Paneth cells. This process is orchestrated by a symphony of niche factors required to maintain intestinal stem cells and to direct their proliferation and differentiation. Among the various mature intestinal epithelial cell types, Paneth cells are unique in their location in the stem cell zone, directly adjacent to intestinal stem cells. Although Paneth cells were first described as an epithelial cell component of the innate immune system due to their expression of anti-microbial peptides, they have been proposed to be niche cells due to their close proximity to intestinal stem cells and expression of niche factors. However, function as a niche cell has been debated since mice lacking Paneth cells retain functional stem cells that continue to replenish the intestinal epithelium. In this review, we summarize the intestinal stem cell niche, including the Notch, Wnt, growth factor, mechanical, and metabolic niche, and discuss how Paneth cells might contribute to these various components. We also present a nuanced view of the Paneth cell as a niche cell. Although not required, Paneth cells enhance stem cell function, particularly during intestinal development and regeneration. Furthermore, we suggest that Paneth cell loss induces ISC remodeling to adjust their niche demands.

Tuft cells promote human intestinal epithelium regeneration as reserve stem cells after irradiation

Intestinal epithelium regeneration is crucial for homeostatic maintenance of the intestinal functions. A recent study published in Nature uncovers tuft cells as an unexpected key player in the regenerative process. Human tuft cells, traditionally recognized for their involvement in immune defense and pathogen protection, were found to exhibit stem cell-like properties following radiation-induced injury. These cells not only resist damage but also have the ability to generate functional stem cells, promoting the repair of the intestinal epithelium. This finding suggests that tuft cells may function as a reserve pool of stem cells, essential for efficient intestinal regeneration after injury.

Molecular Dynamics and Spatial Response of Proliferation and Apoptosis in Wound Healing and Early Intestinal Regeneration of sea cucumber Apostichopus japonicus

The sea cucumber, Apostichopus japonicus, exhibits significant regenerative capabilities. To ensure survival and reduce metabolic costs under adverse conditions, A. japonicus can expel intestine, respiratory trees and other internal organs. It takes only 14 days to regenerate a fully connected, lumen-containing intestine. Despite numerous reports characterizing the cellular events in intestinal regeneration, limited investigation has been conducted on the molecular events that occur during wound healing and the initial stages of regeneration after evisceration. Here, we identified differentially expressed genes (DEGs) during wound healing (6 hours post-evisceration, Aj6hpe) and early intestinal regeneration (Aj1dpe, Aj3dpe, Aj7dpe). Cell proliferation and apoptosis were detected by EdU and TUNEL assays, respectively. Results demonstrated that calcium ion and neuroactive ligand-receptor interaction were involved in the transmission of injury signals from evisceration to Aj1dpe. The main events occurring in the wound healing and early regeneration process were autophagy, apoptosis, dedifferentiation, migration and shutdown of feeding. Cell proliferation was primarily observed during the lumen formation stage. Maximal number of apoptotic cells were found during wound healing stage (6 hpe - 1 dpe). Consequently, the immune response is mainly mobilized by neural regulation after evisceration. Our findings bridge the gap between evisceration and regeneration, illuminating the molecular events that mediate damage response and initiate regeneration. This study significantly advances our understanding of the mechanisms underlying intestinal regeneration.

Eicosapentaenoic acid enhances intestinal stem cell-mediated colonic epithelial regeneration by activating the LSD1-WNT signaling pathway.

Inflammatory bowel disease (IBD) is often associated with impaired proliferation and differentiation of intestinal stem cells (ISCs). Eicosapentaenoic acid (EPA), which is predominantly found in fish oil, has been recognized for its intestinal health benefits, although the potential mechanisms are not well understood. This study aimed to investigate the regulatory role and mechanism of EPA in colonic epithelial regeneration, specifically from the perspective of ISCs. Wild-type mice whose diet was supplemented with 5% EPA-enriched fish oil were subjected to dextran sulfate sodium (DSS) to induce colitis. We utilized intestinal organoids, ISC-specific lysine-specific demethylase 1 (LSD1) knockout mice, and WNT inhibitor-treated mice to explore how EPA influences ISC proliferation and differentiation. ISC proliferation, differentiation and apoptosis were assessed using tdTomato and propidium iodide tracer testing, histological analyses, and immunofluorescence staining. EPA treatment significantly mitigated the symptoms of DSS-induced acute colitis, as evidenced by lower body weight loss and decreased disease activity index, histological scores and proinflammatory cytokine levels. Additionally, EPA increased the numbers of proliferative cells, absorptive cells, goblet cells, and enteroendocrine cells, which enhanced the regeneration of intestinal epithelium. Pretreatment with EPA increased ISC proliferation and differentiation, and protected against TNF-α-induced cell death in intestinal organoids. Mechanistically, EPA upregulated G protein-coupled receptor 120 (GPR120) to induce LSD1 expression, which facilitated ISC proliferation and differentiation in organoids. ISC-specific ablation of LSD1 negated the protective effect of EPA on DSS-induced colitis in mice. Moreover, EPA administration activated the WNT signaling pathway downstream of LSD1 in ISCs, while inhibiting WNT signaling abolished the beneficial effects of EPA. These findings demonstrate that EPA promotes ISC proliferation and differentiation, thereby enhancing colonic epithelial regeneration through the activation of LSD1-WNT signaling. Consequently, dietary supplementation with EPA represents a promising alternative therapeutic strategy for managing IBD.

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.

Liver X receptor unlinks intestinal regeneration and tumorigenesis

Uncontrolled regeneration leads to neoplastic transformation1, 2–3. 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.

Chromatin remodelling in damaged intestinal crypts orchestrates redundant TGFβ and Hippo signalling to drive regeneration.

Cell state dynamics underlying successful tissue regeneration are undercharacterized. In the intestine, damage prompts epithelial reprogramming into revival stem cells (revSCs) that reconstitute Lgr5+ intestinal stem cells (ISCs). Here single-nuclear multi-omics of mouse crypts regenerating from irradiation shows revSC chromatin accessibility overlaps with ISCs and differentiated lineages. While revSC genes themselves are accessible throughout homeostatic epithelia, damage-induced remodelling of chromatin in the crypt converges on Hippo and the transforming growth factor-beta (TGFβ) signalling pathway, which we show is transiently activated and directly induces functional revSCs. Combinatorial gene expression analysis further suggests multiple sources of revSCs, and we demonstrate TGFβ can reprogramme enterocytes, goblet and paneth cells into revSCs and show individual revSCs form organoids. Despite this, loss of TGFβ signalling yields mild regenerative defects, whereas interference in both Hippo and TGFβ leads to profound defects and death. Intestinal regeneration is thus poised for activation by a compensatory system of crypt-localized, transient morphogen cues that support epithelial reprogramming and robust intestinal repair.

Soy polysaccharide maintains colonic homeostasis to protect from dextran sulphate sodium-induced colitis by modulating gut microbiota and intestinal epithelial regeneration

Soy polysaccharide maintains colonic homeostasis to protect from dextran sulphate sodium-induced colitis by modulating gut microbiota and intestinal epithelial regeneration

Gelsolin regulates intestinal stem cell regeneration and Th17 cellular function

Intestinal stem cells (ISCs) are responsible for intestinal homeostasis and are important for the regeneration of damaged intestine. We established an ionizing radiation (IR)-induced intestinal injury model and observed that Gelsolin KO mice had increased radiosensitivity. The deletion of Gelsolin aggravated intestinal damage and reduced the number of ISCs after lethal IR. The intestinal organoid experiments showed that Gelsolin deletion inhibited ISCs function after IR. Notably, RNA sequencing and RT-PCR results showed IL-17 signaling pathway was down-regulated and Th17 cells differentiation was inhibited in Gelsolin KO mice. Moreover, recombinant IL-17 A ameliorated IR-induced intestinal injury and promoted ISCs regeneration. To figure out the role of Gelsolin in Th17 cells differentiation, flow cytometry was used and we found that Gelsolin targets Th17 cells functionality via the p-STAT3/RORγt axis. By establishing the co-culture system, we proved that Th17 cells promoted self-renewal and budding abilities in Gelsolin-deficient organoids. Finally, we found that Gelsolin was protective against DSS-induced colitis and that this protective effect was not specific or limited to the IR induced intestinal injury model. Based on these results, we proved Gelsolin maintained the regeneration of ISCs by sustaining Th17 cells functions via the p-STAT3/RORγt axis.Graphical abstract

Irisin promotes intestinal epithelial cell proliferation via Wnt/β-catenin and focal adhesion kinase signaling pathways

The regeneration of epithelia is crucial for maintaining intestinal homeostasis. Irisin is an exercise-induced hormone originally found to be secreted by skeletal muscles, thereby regulating energy metabolism. Recent studies have revealed that irisin protected against gut inflammation. However, the direct effects of irisin on the intestinal epithelial cells remain to be elucidated. In this study, mouse intestinal organoids were used to assess the effects of irisin on the proliferation of the intestinal epithelial cells. At a concentration of 100 ng/mL irisin significantly increased the growth of the intestinal organoids and upregulated the Wnt/β-catenin and focal adhesion kinase (FAK) signaling pathway genes. Notably, a FAK inhibitor 14 blocked the effects of irisin on the proliferation of the intestinal epithelial cells by inhibiting FAK phosphorylation, as well as the expressions of Wnt target genes. Furthermore, irisin (100 ng/mL) improved the recovery of the intestinal organoids from cellular damages caused by TNF-α, and markedly increased the expression of Wnt target genes in the intestinal epithelial cells. Taken together, irisin activates Wnt/β-catenin and FAK signaling pathways in the intestinal epithelial cells, thereby promoting intestinal epithelial self-renewal under normal homeostatic conditions and intestinal epithelial regeneration upon damages.

BMP suppresses Wnt signaling via the Bcl11b-regulated NuRD complex to maintain intestinal stem cells

Lgr5+ intestinal stem cells (ISCs) are crucial for the intestinal epithelium renewal and regeneration after injury. However, the mechanism underlying the interplay between Wnt and BMP signaling in this process is not fully understood. Here we report that Bcl11b, which is downregulated by BMP signaling, enhances Wnt signaling to maintain Lgr5+ ISCs and thus promotes the regeneration of the intestinal epithelium upon injury. Loss of Bcl11b function leads to a significant decrease of Lgr5+ ISCs in both intestinal crypts and cultured organoids. Mechanistically, BMP suppresses the expression of Bcl11b, which can positively regulate Wnt target genes by inhibiting the function of the Nucleosome Remodeling and Deacetylase (NuRD) complex and facilitating the β-catenin-TCF4 interaction. Bcl11b can also promote intestinal epithelium repair after injuries elicited by both irradiation and DSS-induced inflammation. Furthermore, Bcl11b deletion prevents proliferation and tumorigenesis of colorectal cancer cells. Together, our findings suggest that BMP suppresses Wnt signaling via Bcl11b regulation, thus balancing homeostasis and regeneration in the intestinal epithelium.

Single-cell resolution of intestinal regeneration in pythons without crypts illuminates conserved vertebrate regenerative mechanisms

Canonical models of intestinal regeneration emphasize the critical role of the crypt stem cell niche to generate enterocytes that migrate to villus ends. Burmese pythons possess extreme intestinal regenerative capacity yet lack crypts, thus providing opportunities to identify noncanonical but potentially conserved mechanisms that expand our understanding of regenerative capacity in vertebrates, including humans. Here, we leverage single-nucleus RNA sequencing of fasted and postprandial python small intestine to identify the signaling pathways and cell-cell interactions underlying the python's regenerative response. We find that python intestinal regeneration entails the activation of multiple conserved mechanisms of growth and stress response, including core lipid metabolism pathways and the unfolded protein response in intestinal enterocytes. Our single-cell resolution highlights extensive heterogeneity in mesenchymal cell population signaling and intercellular communication that directs major tissue restructuring and the shift out of a dormant fasted state by activating both embryonic developmental and wound healing pathways. We also identify distinct roles of BEST4+ enterocytes in coordinating key regenerative transitions via NOTCH signaling. Python intestinal regeneration shares key signaling features and molecules with mammalian gastric bypass, indicating that conserved regenerative programs are common to both. Our findings provide different insights into cooperative and conserved regenerative programs and intercellular interactions in vertebrates independent of crypts which have been otherwise obscured in model species where temporal phases of generative growth are limited to embryonic development or recovery from injury.