Intestinal Proliferation Research Articles

Human small intestinal infection by SARS-CoV-2 is characterized by a mucosal infiltration with activated CD8+ T cells

The SARS-CoV-2 pandemic has so far claimed over three and a half million lives worldwide. Though the SARS-CoV-2 mediated disease COVID-19 has first been characterized by an infection of the upper airways and the lung, recent evidence suggests a complex disease including gastrointestinal symptoms. Even if a direct viral tropism of intestinal cells has recently been demonstrated, it remains unclear, whether gastrointestinal symptoms are caused by direct infection of the gastrointestinal tract by SARS-CoV-2 or whether they are a consequence of a systemic immune activation and subsequent modulation of the mucosal immune system. To better understand the cause of intestinal symptoms we analyzed biopsies of the small intestine from SARS-CoV-2 infected individuals. Applying qRT-PCR and immunohistochemistry, we detected SARS-CoV-2 RNA and nucleocapsid protein in duodenal mucosa. In addition, applying imaging mass cytometry and immunohistochemistry, we identified histomorphological changes of the epithelium, which were characterized by an accumulation of activated intraepithelial CD8+ T cells as well as epithelial apoptosis and subsequent regenerative proliferation in the small intestine of COVID-19 patients. In summary, our findings indicate that intraepithelial CD8+ T cells are activated upon infection of intestinal epithelial cells with SARS-CoV-2, providing one possible explanation for gastrointestinal symptoms associated with COVID-19.

Regulation of the Autonomic Nervous System on Intestine.

Intestine is composed of various types of cells including absorptive epithelial cells, goblet cells, endocrine cells, Paneth cells, immunological cells, and so on, which play digestion, absorption, neuroendocrine, immunological function. Intestine is innervated with extrinsic autonomic nerves and intrinsic enteric nerves. The neurotransmitters and counterpart receptors are widely distributed in the different intestinal cells. Intestinal autonomic nerve system includes sympathetic and parasympathetic nervous systems, which regulate cellular proliferation and function in intestine under physiological and pathophysiological conditions. Presently, distribution and functional characteristics of autonomic nervous system in intestine were reviewed. How autonomic nervous system regulates intestinal cell proliferation was discussed. Function of autonomic nervous system on intestinal diseases was extensively reviewed. It might be helpful to properly manipulate autonomic nervous system during treating different intestinal diseases.

How to Obtain a Mega-Intestine with Normal Morphology: In Silico Modelling of Postnatal Intestinal Growth in a Cd97-Transgenic Mouse

Intestinal cylindrical growth peaks in mice a few weeks after birth, simultaneously with crypt fission activity. It nearly stops after weaning and cannot be reactivated later. Transgenic mice expressing Cd97/Adgre5 in the intestinal epithelium develop a mega-intestine with normal microscopic morphology in adult mice. Here, we demonstrate premature intestinal differentiation in Cd97/Adgre5 transgenic mice at both the cellular and molecular levels until postnatal day 14. Subsequently, the growth of the intestinal epithelium becomes activated and its maturation suppressed. These changes are paralleled by postnatal regulation of growth factors and by an increased expression of secretory cell markers, suggesting growth activation of non-epithelial tissue layers as the origin of enforced tissue growth. To understand postnatal intestinal growth mechanistically, we study epithelial fate decisions during this period with the use of a 3D individual cell-based computer model. In the model, the expansion of the intestinal stem cell (SC) population, a prerequisite for crypt fission, is largely independent of the tissue growth rate and is therefore not spontaneously adaptive. Accordingly, the model suggests that, besides the growth activation of non-epithelial tissue layers, the formation of a mega-intestine requires a released growth control in the epithelium, enabling accelerated SC expansion. The similar intestinal morphology in Cd97/Adgre5 transgenic and wild type mice indicates a synchronization of tissue growth and SC expansion, likely by a crypt density-controlled contact inhibition of growth of intestinal SC proliferation. The formation of a mega-intestine with normal microscopic morphology turns out to originate in changes of autonomous and conditional specification of the intestinal cell fate induced by the activation of Cd97/Adgre5.

Protein arginine methyltransferase 1 regulates cell proliferation and differentiation in adult mouse adult intestine

BackgroundAdult stem cells play an essential role in adult organ physiology and tissue repair and regeneration. While much has been learnt about the property and function of various adult stem cells, the mechanisms of their development remain poorly understood in mammals. Earlier studies suggest that the formation of adult mouse intestinal stem cells takes place during the first few weeks after birth, the postembryonic period when plasma thyroid hormone (T3) levels are high. Furthermore, deficiency in T3 signaling leads to defects in adult mouse intestine, including reduced cell proliferation in the intestinal crypts, where stem cells reside. Our earlier studies have shown that protein arginine methyltransferase 1 (PRMT1), a T3 receptor coactivator, is highly expressed during intestinal maturation in mouse.MethodsWe have analyzed the expression of PRMT1 by immunohistochemistry and studied the effect of tissue-specific knockout of PRMT1 in the intestinal epithelium.ResultsWe show that PRMT1 is expressed highly in the proliferating transit amplifying cells and crypt base stem cells. By using a conditional knockout mouse line, we have demonstrated that the expression of PRMT1 in the intestinal epithelium is critical for the development of the adult mouse intestine. Specific removal of PRMT1 in the intestinal epithelium results in, surprisingly, more elongated adult intestinal crypts with increased cell proliferation. In addition, epithelial cell migration along the crypt-villus axis and cell death on the villus are also increased. Furthermore, there are increased Goblet cells and reduced Paneth cells in the crypt while the number of crypt base stem cells remains unchanged.ConclusionsOur finding that PRMT1 knockout increases cell proliferation is surprising considering the role of PRMT1 in T3-signaling and the importance of T3 for intestinal development, and suggests that PRMT1 likely regulates pathways in addition to T3-signaling to affect intestinal development and/or homeostasis, thus affecting cell proliferating and epithelial turn over in the adult.

Acceleration of Small Intestine Development and Remodeling of the Microbiome Following Hyaluronan 35 kDa Treatment in Neonatal Mice.

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined.

MiR-802 regulates Paneth cell function and enterocyte differentiation in the mouse small intestine

The intestinal epithelium is a complex structure that integrates digestive, immunological, neuroendocrine, and regenerative functions. Epithelial homeostasis is maintained by a coordinated cross-talk of different epithelial cell types. Loss of integrity of the intestinal epithelium plays a key role in inflammatory diseases and gastrointestinal infection. Here we show that the intestine-enriched miR-802 is a central regulator of intestinal epithelial cell proliferation, Paneth cell function, and enterocyte differentiation. Genetic ablation of mir-802 in the small intestine of mice leads to decreased glucose uptake, impaired enterocyte differentiation, increased Paneth cell function and intestinal epithelial proliferation. These effects are mediated in part through derepression of the miR-802 target Tmed9, a modulator of Wnt and lysozyme/defensin secretion in Paneth cells, and the downstream Wnt signaling components Fzd5 and Tcf4. Mutant Tmed9 mice harboring mutations in miR-802 binding sites partially recapitulate the augmented Paneth cell function of mice lacking miR-802. Our study demonstrates a broad miR-802 network that is important for the integration of signaling pathways of different cell types controlling epithelial homeostasis in the small intestine.

Microbial recognition regulates intestinal epithelial growth in homeostasis and disease.

The intestine is constantly exposed to a dynamic community of microbes. Intestinal epithelial cells respond to microbes through evolutionarily conserved recognition pathways, such as the immune deficiency (IMD) pathway of Drosophila, the Toll-like receptor (TLR) response of flies and vertebrates, and the vertebrate nucleotide-binding oligomerization domain (NOD) pathway. Microbial recognition pathways are tightly controlled to respond effectively to pathogens, tolerate the microbiome, and limit intestinal disease. In this review, we focus on contributions of different model organisms to our understanding of how epithelial microbe recognition impacts intestinal proliferation and differentiation in homeostasis and disease. In particular, we compare how microbes and subsequent recognition by the intestine influences barrier integrity, intestinal repair and tumorigenesis in Drosophila, zebrafish, mice, and organoids. In addition, we discuss the importance of microbial recognition in homeostatic intestinal growth and discuss how immune pathways directly impact stem cell and crypt dynamics.

Neonatal Intestinal Macrophages Promote Microvascular Development through an IGF‐1‐dependent Mechanism and Lack of Macrophage‐derived IGF‐1 Predisposes Newborn Mice to Necrotizing Enterocolitis

Defective intestinal microvascular development has been previously shown to play a role in necrotizing enterocolitis (NEC) pathogenesis. Decreased serum levels of IGF-1 in premature infants are associated with a higher risk of developing NEC and we recently found that serum and intestinal tissue IGF-1 level are decreased in a neonatal mouse NEC model. In the embryo, macrophages have been reported to promote angiogenesis. Here we hypothesize that neonatal intestinal macrophages promote endothelial cell proliferation and angiogenesis by producing IGF-1, thus protecting against NEC development. For this purpose, we first examined the role of IGF-1 on intestinal endothelial cell sprouting in vitro using IGF-1 and IGF-1R inhibitor and on intestinal endothelial cell proliferation in vivo using IGF-1R inhibitor. Secondly, using mice with IGF-1-deficient-macrophages and IGF-1-sufficient littermates, we assessed whether macrophage-derived IGF-1 plays a role in perinatal microvascular development by examining endothelial cell proliferation in vivo and endothelial cell sprouting in vitro in Matrigel co-cultures. Finally, we examined whether macrophage-derived IGF-1 protects against NEC. We found that, neonatal intestinal CX3CR1+ macrophages were essential for small intestinal endothelial cells to sprout in Matrigel, which process was further enhanced by exogenous IGF-1 and inhibited by the selective IGF-1R inhibitor picropodophyllin (PPP). Intestinal endothelial cell proliferation was also inhibited by PPP in vivo, to a similar extent as observed during NEC development. Furthermore, neonatal IGF-1-deficient macrophages significantly decreased pro-angiogenic activity in vitro. Mice with IGF-1-deficient-macrophages had less robust intestinal endothelial proliferation and decreased intestinal VEGF protein expression in vivo. Lastly, pups with IGF-1-deficient macrophages had increased incidence of severe NEC-like intestinal injury and mortality. In conclusion, neonatal intestinal macrophages are critical for promoting intestinal microvascular growth and for protecting pups from NEC development via IGF-1 production.

Efficacy and Safety of Systemic and Locoregional Cisplatin Chronotherapy in Rats with Ovarian Carcinoma.

AimAlterations in circadian rhythms caused by tumor growth are thought to be clinically relevant as they affect the prognosis and treatment response. We aimed to evaluate the chronotherapeutic approach in rats with ovarian cancer receiving cisplatin intravenously (IV) or with hyperthermic intraperitoneal chemoperfusion (HIPEC) and to assess daily variations in tumor and intestinal epithelium proliferation.MethodsIn the pilot study, we used 12 intact rats and 12 rats with transplantable ovarian cancer, which were euthanized at ZT0 (08:00, lights on), ZT6, ZT12 and ZT18. In the main study, we used 45 rats with transplantable ovarian cancer. Animals were randomized into five groups: control, HIPEC with cisplatin at ZT0 (08:00), HIPEC with cisplatin at ZT12 (20:00), IV cisplatin at ZT0 and IV cisplatin at ZT12. We assessed the proliferation rate of tumor and small intestinal epithelium, apoptosis in small intestinal epithelium, and levels of γ-H2AX (DNA damage/repair marker) in kidneys and liver. Survival was calculated in each group.ResultsAscitic ovarian cancer disrupted daily variations in intestinal epithelium proliferation and DNA damage/repair in rats. Ovarian carcinoma exhibited no daily variation in mitotic activity. In animals receiving IV cisplatin, massive cell damage in the renal medulla and cystic changes within renal tubules were observed, unlike in rats receiving HIPEC. Tumor mitotic activity was lower in morning-treated groups. The median survival of rats in the control group was 8.5 days (95% CI 6.0–22.0), in HIPEC at ZT0 40.5 days (95% CI 28.0–47.0, p<0.001) and in HIPEC at ZT12 32.0 days (95% CI 28.0–37.0, p<0.001).ConclusionIn a rat model, ovarian tumor growth disrupted daily variations in intestinal epithelium proliferation and caused genotoxic stress in tumor-free tissues. HIPEC with cisplatin at ZT0 had a better efficacy/toxicity profile than HIPEC with cisplatin at ZT12 and IV administration at both time points.

JAM‐A signals through the Hippo pathway to regulate intestinal epithelial proliferation

The intestinal mucosa is lined by a columnar epithelial monolayer that serves as a dynamic interface, regulating barrier function and homeostasis. Perturbation of homeostasis, including changes in intestinal epithelial cell (IEC) proliferation and migration, can give rise to pathological states including ulcerative colitis and cancer. Regulation of proliferation and migration is a complex process coordinated, in part, by signaling events emanating from tight junction proteins at cell-cell contacts. One tight junction protein that has been linked to regulation of cellular proliferation is Junctional Adhesion Molecule A (JAM-A). JAM-A forms homodimers in cis and trans through interactions between its extracellular immunoglobulin-like domains. Loss of JAM-A results in enhanced IEC proliferation that has been linked to loss of homophilic interactions and Akt-dependent, beta-catenin signaling. However, JAM-A contributions to other signaling pathways that regulate cell proliferation are poorly understood. Since the Hippo signaling pathway is a well-known regulator of cellular proliferation, differentiation, and apoptosis, we examined whether loss of JAM-A alters Hippo pathway activity. We assessed activity of the Hippo transcriptional coactivator, Yes-1 Associated Protein (YAP), in JAM-A deficient IEC by gene-reporter activity assay and immunoblotting and observed significant increases, suggesting that JAM-A may interact with Hippo pathway constituents upstream of YAP. Immunolabeling studies with monolayers of IEC revealed association of JAM-A with two Hippo pathway constituents, Large Tumor Suppressor Kinase (LATS1) and Merlin. Co-immunoprecipitation experiments confirmed LATS1 and Merlin association with JAM-A. Moreover, phosphoprotein specific immunoblotting studies on JAM-A deficient IEC revealed decreased Hippo pathway activity characterized by decreased LATS1 activity and subsequent increased YAP activity. Such findings are consistent with JAM-A signaling upstream of Merlin and LATS1 and coordinating downstream Hippo signaling. Since there is evidence suggesting that dimerization of JAM-A is a required signal that suppresses IEC proliferation, we performed experiments using an exogenous overexpression system to study effects of a dimerization deficient JAM-A mutant on Hippo signaling. Phosphoprotein specific immunoblotting and EdU incorporation revealed that overexpression of full-length JAM-A resulted in activation of Hippo signaling, suppressing cell proliferation compared to empty vector control cells. However, overexpression of a dimerization defective JAM-A mutant protein lacking the distal immunoglobulin loop (DL1) was unable to activate Hippo signaling and suppress cell proliferation. Based on these observations, we propose that homodimerization of JAM-A functions as a cell-cell contact sensor, initiating downstream Hippo signaling to suppress IEC proliferation. These findings have important implications for understanding effects of altered proliferation on mucosal wound repair, as well as in morbidity associated with certain cancers which have been reported to express decreased levels of JAM-A protein.

33 Profiling miRNA transcripts in the equine hindgut by quantitative PCR

Gastrointestinal (GI) homeostasis in a horse results from dynamic interactions between a horse's gut physiology and the microbes in the various compartments. MicroRNAs (miRNA), single-stranded 20–22 basepair RNA molecules involved in post-transcriptional control of gene expression, have been implicated as an essential mechanism for control of gastrointestinal physiology and communication between host and microbe. Researchers have described how host-derived miRNAs influence microbial communities' composition in the GI. We have recently described how the pelvic flexure separates distinct microbial populations in the equine hindgut and subsequently have wondered if equine miRNA transcripts expressed by GI tissues could have a role in maintaining this separation. Investigations to characterize miRNAs' expression profile and other non-coding RNAs in the equine GI tract are limited. To address this, it is critical that we first know something about the expression of non-coding transcripts in the equine GI. This study investigated miRNA expression in tissues of the hindgut surrounding the pelvic flexure. RNA was isolated from the intestinal epithelium of 3 4-year-old American Quarter Horses collected from the right and left ventral colon (VC), pelvic flexure (PF), and right and left dorsal colon (DC). The miRNA transcripts were reverse transcribed using the miScript II RT kit, and relative abundance was quantified using the miScript SYBR Green PCR kit and primer sets for 286 annotated mature equine miRNAs. Biological replicates were pooled, and differential expression was determined following normalization by the delta Ct = Ct(target) – Ct(sample) method. A total of 230 miRNA transcripts were expressed in at least one GI location, with 60 expressed in all 5 locations. Twenty-eight transcripts had expression restricted to a single site, 5 of which were only expressed in the pelvic flexure. Additionally, 42 transcripts have patterns of expression across a subset of anatomical locations. Notably, 10 transcripts were expressed in the VC and PF, 5 transcripts were expressed in the DC and PF, and 15 transcripts were expressed in the VC and DC but not PF. Pathway and target analysis for the miRNAs with compartment restricted expression was performed using DIANA TOOLS. Of note, miRNA transcripts expressed only in the PF were predicted to target genes in the Hippo signaling pathway, which is associated with the regulation of intestinal tissue proliferation and homeostasis. Further investigation of miRNA expression in the equine hindgut will improve our understanding of gastrointestinal homeostasis's regulatory processes.

Kampo medicines Rikkunshito and Hangeshashinto prevent cisplatin-induced intestinal mucosal injury in rats

Background/PurposeWe examined the effects and mechanisms of rikkunshito (RKT) and hangeshashinto (HST) on cisplatin-induced mucosal injuries in the rat small bowel. MethodsJuvenile rats were divided into 6 groups: sham control, cisplatin injection without kampo medicines, and cisplatin injection with oral administration of low and high doses of RKT (1000 mg/kg and 2000 mg/kg) and HST (500 mg/kg and 1000 mg/kg). Fecal condition, intestinal morphological changes, enterocyte proliferation, and enterocyte apoptosis were assessed. ResultsDiarrhea and atrophy of ileal villi observed in the cisplatin group were significantly improved in all kampo groups. Injury scores of the jejunum were significantly lower with RKT (2000 mg/kg) and HST (500 and 1000 mg/kg) than with cisplatin, and those of the ileum were significantly lower with HST (500 and 1000 mg/kg) than with cisplatin. Enterocyte proliferation of the jejunum was significantly increased with RKT (2000 mg/kg) and HST (500 mg/kg) compared with cisplatin, and those of the ileum were significantly increased in all kampo groups compared with the cisplatin group. Jejunal and ileal apoptosis following cisplatin administration was significantly inhibited by HST. ConclusionsRKT and HST prevented cisplatin-induced intestinal mucosal injury with increasing proliferation of intestinal epithelial cells. HST also attenuated cisplatin-induced crypt cell apoptosis.

A28 CHARACTERIZING THE ROLE OF NR4A1 IN THE REGULATION OF INTESTINAL SMOOTH MUSCLE CELL PHENOTYPE AND FUNCTION

Abstract Background Intestinal fibrosis and stricture formation are common complications of Crohn’s disease (CD). Recently, smooth muscle hypertrophy/hyperplasia have gained greater recognition as a driver of stricture formation, rather than an increase in fibrosis alone. Despite advances in treatment of CD, current therapies do little to prevent or reverse strictures. NR4A1 is an orphan nuclear receptor that is anti-fibrotic in non-intestinal systems and exhibits anti-proliferative effects in smooth muscle cells (SMCs). NR4A1 gene variants have been associated with increased risk of IBD, however, mechanisms regulating NR4A1 expression and its role in intestinal SMC function have not been investigated. Aims To characterize the role of NR4A1 presence and activation in modulating intestinal SMC phenotype. Methods Primary intestinal SMCs were isolated from Nr4a1+/+and Nr4a1-/-mice. A commercially sourced human primary intestinal SMC line was also used. Mass spectrometry identified proteomic differences between Nr4a1+/+and Nr4a1-/-SMCs. To assess the role of NR4A1 in regulating SMC growth, basal and platelet-derived growth factor-BB (PDGF-BB)-induced proliferation were quantified. NR4A1 activation was induced by selective agonists, cytosporone B (Csn-B) and 6-mercaptopurine (6-MP). Cellular respirometry was used to determine metabolism in Nr4a1+/+and Nr4a1-/-SMCs. Expression of NR4A1 and phenotypic switching mediators were assessed by qPCR. Immunofluorescence was used to assess contractile markers and cell morphology. Results Proteomic analysis revealed increased expression of proteins related to the cell cycle, metabolism, and extracellular matrix synthesis in Nr4a1-/-SMCs. Nr4a1+/+SMCs upregulated proteins involved in smooth muscle contraction and was supported by higher mRNA levels of myocardin and lower Krüppel-like factor 4. Nr4a1-/-cells were more proliferative compared to Nr4a1+/+cells under basal conditions. Treating human intestinal SMCs with Csn-B attenuated proliferation induced by PDGF-BB. Similar effects were observed in Nr4a1+/+SMCs, however, the anti-proliferative effect of Csn-B was absent in Nr4a1-/-cells. Nr4a1-/-SMCs had higher maximal respiration, spare respiratory capacity, and glycolysis. NR4A1 expression was rapidly induced by Csn-B/6-MP and PDGF-BB, the latter suggesting a potential negative feedback mechanism to control mitogen-induced SMC proliferation. Conclusions Our results suggest that NR4A1 is a regulator of intestinal SMC proliferation, bioenergetics, and phenotype. Its induction by mitogens may contribute to a negative feedback loop to control smooth muscle growth. These data support targeting NR4A1 to treat excessive smooth muscle hypertrophy/hyperplasia that contributes to tissue remodelling observed in fibrostenotic CD. Funding Agencies CCC, CIHR

Differential effects of commensal bacteria on progenitor cell adhesion, division symmetry and tumorigenesis in the Drosophila intestine

Microbial factors influence homeostatic and oncogenic growth in the intestinal epithelium. However, we know little about immediate effects of commensal bacteria on stem cell division programs. In this study, we examined the effects of commensal Lactobacillus species on homeostatic and tumorigenic stem cell proliferation in the female Drosophila intestine. We identified Lactobacillus brevis as a potent stimulator of stem cell divisions. In a wild-type midgut, L. brevis activates growth regulatory pathways that drive stem cell divisions. In a Notch-deficient background, L. brevis-mediated proliferation causes rapid expansion of mutant progenitors, leading to accumulation of large, multi-layered tumors throughout the midgut. Mechanistically, we showed that L. brevis disrupts expression and subcellular distribution of progenitor cell integrins, supporting symmetric divisions that expand intestinal stem cell populations. Collectively, our data emphasize the impact of commensal microbes on division and maintenance of the intestinal progenitor compartment.

Remote ischemic conditioning avoids the development of intestinal damage after ischemia reperfusion by reducing intestinal inflammation and increasing intestinal regeneration.

Midgut volvulus is a potentially life-threatening condition which is based on intestinal ischemia and reperfusion (I/R) injury. Remote ischemia conditioning (RIC) applied to a limb can protect distant organs such as heart and kidney. The aims of this study were to investigate the effect of RIC on a model of midgut volvulus and to explore its underlying mechanism of action. Six-weeks old C57BL/6 mice were studied: (a) sham (n = 4): laparotomy alone. (b) Intestinal I/R injury (n = 5): occlusion of the superior mesenteric artery (SMA) for 45min followed by reperfusion. (c) Intestinal I/R (as in group above) with RIC immediately after reperfusion (n = 5). RIC consisted of 4 cycles of 5min hind limb ischemia followed by 5min reperfusion. 24-h after laparotomy, animals were euthanized, and the small intestine (same distance from cecum) was harvested. The intestine was examined for inflammatory cytokines (TNF-α and IL-6), epithelial proliferation marker Ki67 and stem cell marker Lgr5 expression. Compared to sham, the small intestine of IR mice had more intestinal damage, increased expression of inflammatory cytokines, decreased intestinal proliferation and stem cell activity. RIC significantly counteracted all these changes. Remote ischemia conditioning avoids intestinal damage due to I/R injury. This beneficial effect is associated with decreased intestinal inflammation and enhanced intestinal regeneration. This study implicates that RIC is a novel non-invasive intervention to reduce the intestinal damage occurring in midgut volvulus.

Defined matrices bring IBD to 3D.

An immune cell population enriched in inflamed gut tissue is shown to play a role in driving CD44+ intestinal organoid proliferation, while also regulating extracellular matrix deposition and remodelling in a synthetic hydrogel platform.

The Role of pHi in Intestinal Epithelial Proliferation-Transport Mechanisms, Regulatory Pathways, and Consequences.

During the maturation of intestinal epithelial cells along the crypt/surface axis, a multitude of acid/base transporters are differentially expressed in their apical and basolateral membranes, enabling processes of electrolyte, macromolecule, nutrient, acid/base and fluid secretion, and absorption. An intracellular pH (pHi)-gradient is generated along the epithelial crypt/surface axis, either as a consequence of the sum of the ion transport activities or as a distinctly regulated entity. While the role of pHi on proliferation, migration, and tumorigenesis has been explored in cancer cells for some time, emerging evidence suggests an important role of the pHi in the intestinal stem cells (ISCs) proliferative rate under physiological conditions. The present review highlights the current state of knowledge about the potential regulatory role of pHi on intestinal proliferation and differentiation.

R-Spondin1 enhances wnt signaling and decreases weight loss in short bowel syndrome zebrafish

BackgroundR-spondins, including R-spondin 1 (RSPO1), are a family of Wnt ligands that help to activate the canonical Wnt/β-catenin pathway, which is critical for intestinal epithelial cell proliferation and maintenance of intestinal stem cells. This proliferation underpins the epithelial expansion, or intestinal adaptation (IA), that occurs following massive bowel resection and short bowel syndrome (SBS). The purpose of this study was to identify if recombinant human RSPO1 (rhRSPO1) could be serially administered to SBS zebrafish to enhance cellular proliferation and IA. MethodsAdult male zebrafish were assigned to four groups: sham + PBS, SBS + PBS, sham + rhRSPO1, and SBS + rhRSPO1. Sham fish had a laparotomy alone. SBS fish had a laparotomy with distal intestinal ligation and creation of a proximal stoma. Fish were weighed at initial surgery and then weekly. rhRSPO1 was administered post-operatively following either a one- or two-week dosing schedule with either 3 or 5 intraperitoneal injections, respectively. Fish were harvested at 7 or 14 days with intestinal segments collected for analysis. ResultsRepeated intraperitoneal injection of rhRSPO1 was feasible and well tolerated. At 7 days, intestinal epithelial proliferation was increased by rhRSPO1. At 14 days, SBS + rhRSPO1 fish lost significantly less weight than SBS + PBS fish. Measurements of intestinal surface area were not increased by rhRSPO1 administration but immunofluorescent staining for β-catenin and gene expression for cyclin D1 was increased. ConclusionsIntraperitoneal injection of rhRSPO1 decreased weight loss in SBS zebrafish with increased β-catenin + cells and cyclin D1 expression at 14 days, indicating improved weight maintenance might result from increased activation of the canonical Wnt pathway.

Serotonin as a Mitogen in the Gastrointestinal Tract: Revisiting a Familiar Molecule in a New Role.

Serotonin signaling is ubiquitous in the gastrointestinal (GI) system, where it acts as a neurotransmitter in the enteric nervous system (ENS) and influences intestinal motility and inflammation. Since its discovery, serotonin has been linked to cellular proliferation in several types of tissues, including vascular smooth muscle, neurons, and hepatocytes. Activation of serotonin receptors on distinct cell types has been shown to induce well-known intracellular proliferation pathways. In the GI tract, potentiation of serotonin signaling results in enhanced intestinal epithelial proliferation, and decreased injury from intestinal inflammation. Furthermore, activation of the type 4 serotonin receptor on enteric neurons leads to neurogenesis and neuroprotection in the setting of intestinal injury. It is not surprising that the mitogenic properties of serotonin are pronounced within the GI tract, where enterochromaffin cells in the intestinal epithelium produce 90% of the body’s serotonin; however, these proliferative effects are attributed to increased serotonin signaling within the ENS compartment as opposed to the intestinal mucosa, which are functionally and chemically separate by virtue of the distinct tryptophan hydroxylase enzyme isoforms involved in serotonin synthesis. The exact mechanism by which serotonergic neurons in the ENS lead to intestinal proliferation are not known, but the activation of muscarinic receptors on intestinal crypt cells indicate that cholinergic signaling is essential to this signaling pathway. Further understanding of serotonin’s role in mucosal and enteric nervous system mitogenesis may aid in harnessing serotonin signaling for therapeutic benefit in many GI diseases, including inflammatory bowel disease, malabsorptive conditions, and cancer.

Dose-response and functional role of whey permeate as a source of lactose and milk oligosaccharides on intestinal health and growth of nursery pigs.

Two experiments were conducted to evaluate dose-response and supplemental effects of whey permeate on growth performance and intestinal health of nursery pigs. In experiment (exp.) 1, 1,080 pigs weaned at 6.24 kg body weight (BW) were allotted to five treatments (eight pens/treatment) with increasing levels of whey permeate in three phases (from 10% to 30%, 3% to 23%, and 0% to 9% for phase 1, 2, and 3, respectively) fed until 11 kg BW and then fed a common phase 4 diet (0% whey permeate) until 25 kg BW in a 48-d feeding trial. Feed intake and BW were measured at the end of each phase. In exp. 2, 1,200 nursery pigs at 7.50 kg BW were allotted to six treatments (10 pens/treatment) with increasing levels of whey permeate from 0% to 18.75% fed until 11 kg BW. Feed intake and BW were measured during 11 d. Six pigs per treatment (1 per pens) were euthanized to collect the jejunum to evaluate tumor necrosis factor-alpha, interleukin-8 (IL-8), transforming growth factor-beta 1, mucin 2, histomorphology, digestive enzyme activity, crypt cell proliferation rate, and jejunal mucosa-associated microbiota. Data were analyzed using contrasts in the MIXED procedure and a broken-line analysis using the NLIN procedure of SAS. In exp. 1, increasing whey permeate had a quadratic effect (P < 0.05) on feed efficiency (G:F; maximum: 1.35 at 18.3%) in phase 1. Increasing whey permeate linearly increased (P < 0.05) average daily gain (ADG; 292 to 327 g/d) and G:F (0.96 to 1.04) of pigs in phase 2. In exp. 2, increasing whey permeate linearly increased (P < 0.05) ADG (349 to 414 g/d) and G:F (0.78 to 0.85) and linearly increased (P < 0.05) crypt cell proliferation rate (27.8% to 37.0%). The breakpoint from a broken-line analysis was obtained at 13.6% whey permeate for maximal G:F. Increasing whey permeate tended to change IL-8 (quadratic, P = 0.052; maximum: 223 pg/mg at 10.9%), to decrease Firmicutes:Bacteroidetes (P = 0.073, 1.59 to 1.13), to increase (P = 0.089) Bifidobacteriaceae (0.73% to 1.11%), and to decrease Enterobacteriaceae (P = 0.091, 1.04% to 0.52%) and Streptococcaceae (P = 0.094, 1.50% to 0.71%) in the jejunal mucosa. In conclusion, dietary inclusion of whey permeate increased the growth of nursery pigs from 7 to 11 kg BW. Pigs grew most efficiently with 13.6% whey permeate. Improvement in growth performance is partly attributed to stimulating intestinal immune response and enterocyte proliferation with positive changes in jejunal mucosa-associated microbiota in nursery pigs.