Renshen Baidusan Regulates Autophagy to Repair Mucosa in Ulcerative Colitis / 中国实验方剂学杂志

ObjectiveTo explore the mechanism of Renshen Baidusan in repairing intestinal mucosa in ulcerative colitis （UC） by regulating autophagy to scavenge peroxides. MethodThe mouse model of UC was induced by free drinking of 3.0% dextran sulphate sodium （DSS） solution. Sixty male C57BL/6J mice were randomized into normal， model， mesalazine （0.3 g·kg-1）， and high-， medium-， and low-dose （12.35， 8.22， 4.11 g·kg-1， respectively） Renshen Baidusan groups （n=10）. The mice were administrated with corresponding drugs by gavage for 7 consecutive days. The colon tissue was stained with hematoxylin-eosin （HE） to reveal the pathological changes， and Alcian blue-Periodic acid Scheff （PAS/AB） staining was employed to observe the goblet cell changes. The fluorescence expression of reactive oxygen species （ROS） in the colon tissue was detected by the immunofluorescence assay. The activity of superoxide dismutase （SOD） and the content of malondialdehyde （MDA） were measured by the biochemical methods. Western blot was employed to determine the expression levels of proliferating cell nuclear antigen （PCNA）， microtubule-associated protein 1 light chain 3 （LC3）， leucine-rich repeat-containing G protein-coupled receptor 5 （LGR5）， and p62. ResultDestroyed mucosal epithelial structure， intestinal gland destruction， loss of goblet cells， and massive infiltration of inflammatory cells appeared in the model group. Compared with the normal group， the model group showed increased tissue damage injury （TDI） score of the colon tissue， decreased SOD activity and LC3Ⅱ/Ⅰ， PCNA value， and elevated levels of p62， MDA， ROS， and LGR5 （P<0.05）. Compared with the model group， different doses of Renshen Baidusan decreased the TDI score， promoted the generation of new goblet cells， elevated the levels of PCNA， LGR5， SOD， and LC3Ⅱ/Ⅰ， and lowered the levels of p62， MDA， and ROS （P<0.05）. Moreover， the low dose group showed the best performance （P<0.05）. ConclusionRenshen Baidusan can promote intestinal epithelial repair by activating intestinal autophagy， alleviating oxidative stress， and promoting intestinal stem cell proliferation and differentiation.

Role of intestinal stem cells in prevention of radiation-induced intestinal injury / 中华放射医学与防护杂志

At present, there is no effective treatment method of radiation-induced intestinal injury. Clinically, only symptomatic remission therapy can be used. Intestinal stem cells (ISCs) have strong renewal ability, which is an important part of intestinal structure regeneration. To promote the recovery of the number and function of ISCs has been a research hotspot in the treatment of radiation gastrointestinal syndrome. This article introduces the important role of ISCs in the protection of radiation-induced intestinal injury and its clinical application significance from the classification and regulatory mechanism of ISCs, and drugs that regulate the damage, apoptosis and repair of stem cells, so as to provide reference for the future research on the role of intestinal stem cells in radiation protection.

Mechanism and influencing factors of Lgr5 in intestinal stem cells / 医学研究生学报

The leucine repeat-rich G-protein-coupled receptor 5 (Lgr5), which expressed at the bottom of the crypt, not only acts as a marker of intestinal stem cells, but also induces cytonemes for transfering signaling effectors by internalization, influences proliferation by Wnt /β-catenin pathway, and promotes cytoskeletal structure, cell adhesion of intestinal stem cells（ISCs） via the IQGAP1. In addition, Lgr5 can be affected by the regulation of IL-1β、IL-22、miR-100-5p and others. Besides, intestinal microbiota change the localization of Lgr5+ cells in cript to induce apoptosis increased. Therefore，Lgr5 is influenced by many factors, which may play an important role in the proliferation, differentiation and stability of ISCs.

Effect of Rheum officinale on activity of intestinal stem cells in Drosophila melanogaster induced by SDS toxicity / 中草药

Objective: To explore the effect of Rheum officinale extracts (ROE) on activity of intestinal stem cells of Drosophila melanogaster. Methods: The control group was fed with normal cornmeal-yeast medium, and the experimental group was fed with cornmeal-yeast medium containing 0.05 or 0.1 g/mL ROE. In the experiment, the gut damage was induced by feeding D. melanogaster with toxic compounds. The effects of ROE on survival rate, number and morphology of progenitor cells, proliferation and differentiation of intestinal stem cells, expression of reactive oxygen species (ROS), number of intestinal epithelial dead cells and life span of D. melanogaster were detected and analyzed. Results: ROE (0.05 and 0.1 g/mL) could increase the survival rate of D. melanogaster induced by toxic compounds. ROE (0.1 g/mL) could decrease SDS-induced ROS levels, reduce the number of intestinal epithelial dead cells, inhibit excessive proliferation and differentiation of intestinal stem cell, alleviate the excessive accumulation of progenitor cells, thereby maintain homeostasis in the gut. In addition, ROE could prolong the lifespan of D. melanogaster. Conclusion: ROE can inhibit excessive proliferation and differentiation of intestinal stem cells, enhance gut immune function, and prolong the life span of D. melanogaster.

Stem Cells in the Intestine: Possible Roles in Pathogenesis of Irritable Bowel Syndrome

Irritable bowel syndrome is one of the most common functional gastrointestinal (GI) disorders that significantly impair quality of life in patients. Current available treatments are still not effective and the pathophysiology of this condition remains unclearly defined. Recently, research on intestinal stem cells has greatly advanced our understanding of various GI disorders. Alterations in conserved stem cell regulatory pathways such as Notch, Wnt, and bone morphogenic protein/TGF-β have been well documented in diseases such as inflammatory bowel diseases and cancer. Interaction between intestinal stem cells and various signals from their environment is important for the control of stem cell self-renewal, regulation of number and function of specific intestinal cell types, and maintenance of the mucosal barrier. Besides their roles in stem cell regulation, these signals are also known to have potent effects on immune cells, enteric nervous system and secretory cells in the gut, and may be responsible for various aspects of pathogenesis of functional GI disorders, including visceral hypersensitivity, altered gut motility and low grade gut inflammation. In this article, we briefly summarize the components of these signaling pathways, how they can be modified by extrinsic factors and novel treatments, and provide evidenced support of their roles in the inflammation processes. Furthermore, we propose how changes in these signals may contribute to the symptom development and pathogenesis of irritable bowel syndrome.

Physiological understanding of host-microbial pathogen interactions in the gut

The gut epithelial barrier, which is composed of the mucosal layer and the intestinal epithelium, has multiple defense mechanisms and interconnected regulatory mechanisms against enteric microbial pathogens. However, many bacterial pathogens have highly evolved infectious stratagems that manipulate mucin production, epithelial cell-cell junctions, cell death, and cell turnover to promote their replication and pathogenicity in the gut epithelial barrier. In this review, we focus on current knowledge about how bacterial pathogens regulate mucin levels to circumvent the epithelial mucus barrier and target cell-cell junctions to invade deeper tissues and increase their colonization. We also describe how bacterial pathogens manipulate various modes of epithelial cell death to facilitate bacterial dissemination and virulence effects. Finally, we discuss recent investigating how bacterial pathogens regulate epithelial cell turnover and intestinal stem cell populations to modulate intestinal epithelium homeostasis.

Establishment of lineage tracing method of mice small intestinal stem cell and application in radiation injury / 解放军医学杂志

Objective To establish a lineage tracing method with Lgr5-EGFP-CreERT2/ROSA26-stop-EYFP mouse for observing the role of Lgr5+ intestinal stem cells in the renovation of small intestine tissue, and investigate the effects of radiation on the reconstruction of small intestinal stem cell tissue. Methods-Lgr5-EGFP-CreERT2/ROSA26-stop-EYFP mice were identified by genotype analysis. Tamoxifen was used to induce the expression of fluorescent protein in mice. The differentiation of intestinal stem cells induced by Tamoxifen was observed by laser confocal microscopy. Lgr5-EGFP-CreERT2/ROSA26-stop-EYFP mice were irradiated with60Co γ-rays, and the effects of irradiation on the reconstruction of small intestinal stem cell tissue were examined. Results-Double positive mice were obtained by identification of Lgr5 gene (174bp) in DNA extraction from the mice tail with PCR method. In mice treated with single injection of Tamoxifen (100mg/kg), it was observed by laser confocal scanning microscopy that the Lgr5+ intestinal stem cells started dividing at the 5th day after inducement, reached the top of the villi at the 7th day, fluorescence appeared in a few of whole intestinal villi at the 14th day, and spread over more intestinal villi with dense fluorescence at the 45th day. However, in mice exposed to 15Gy irradiation, the intestinal villi fell off seriously without fluorescence in crypts. Conclusion-The lineage tracing model of intestinal stem cell has been successfully established and then used to evaluate the irradiation injuries to intestinal stem cells.

Célula tronco tumoral: novo conceito em carcinogênese colorretal / Câncer stem cells: a new concept in colorectal carcinogenesis

Apesar dos grandes avanços obtidos pelos estudos utilizando técnicas de biologia molecular diversas controvérsias persistem a respeito do mecanismo de carcinogênese colorretal. Ao longo do último ano, entretanto, observamos na literatura o surgimento de um novo conceito referente à existência de um conjunto de células situadas nas bases das criptas intestinais, as quais apresentam características bastante distintas do restante das células epiteliais. Estas células, denominadas como células tronco intestinais, apresentam-se de forma indiferenciada e com um ciclo de vida com duração superior a um ano. Desta forma, justifica-se assim nestas células a possibilidade da ocorrência de um acúmulo de mutações, etapa considerada essencial para o desenvolvimento do processo neoplásico, e que seria improvável de ocorrer em um colonócito normal, cujo ciclo de vida dura em média cinco dias. Outra importante evidência da participação destas células tronco no mecanismo de carcinogênese foi demonstrada por estudos capazes de reproduzir a formação de tecidos neoplásicos com a mesma característica do tumor original, a partir do implante de um reduzido número destas células em modelos experimentais, o que não se obtém através do implante de um grande número de células tumorais normais. Sabendo-se que a presença de uma mutação do gene APC é uma etapa precoce no processo de carcinogênese colorretal, acredita-se que esta exerça este papel contribuindo para a ocorrência de uma superpopulação de células tronco intestinais, levando a um desequilíbrio proliferativo na mucosa intestinal.

Despite the great number of studies using molecular biology tools several questions remain about the mechanisms of colorectal carcinogenesis. A recent concept has emerged from the literature regarding the existence of a specific group of indiferentiated cells situated at the bottom of intestinal crypts with a long life cycle that may last more than one year, described as intestinal stem cells. This particular property may explain the expected occurrence of a sequence of mutations necessary to the development of a carcinoma, which cannot be observed in a normal colonocyte with a mean cycle life of five days. Another important evidence to this concept is the induction in rodents of a tumor with similar characteristics to the original human carcinoma by injection of a small number of these stem cells, which is not achieved by using large number of normal cancer cells. It is suggested that mutation of APC gene, present as an early step in most colorectal carcinomas, may contribute to a superpopulation of intestinal stem cells with consequent disturbance of proliferative epithelial balance.

Cloning and functional analysis of the promoter region of an intestinal stem cell specific expressed gene,Musashi-1 / 肠外与肠内营养

Objective:To clone and functionally analyze the promoter region of an intestinal specific expressed gene,Musashi-1.Methods:The 5' flanking region of MSI-1 gene was cloned from C57BL/6J mouse genomic DNA using PCR-mediated recombination.Expression of MSI-1 mRNA was determined in Colon26 and B16 cell lines using Northern Blotting.Various 5′-deletion recombination plasmids were constructed and transfected transiently into the Colon26 cell line.Luciferase reporter assay was performed to determine the relative transcriptional activities of various 5′-deltion fragments.Results:MSI-1 mRNA was expressed in both Colon26 and B16 cell lines,but much higher in Colon26 cell line.The transcriptional activity of DNA fragment from 73bp downstream to 4 939bp upstream the(MSI-1) gene transcriptional start site was 29.9 fold of the pGL3-basic empty vector.Conclusion:(pSMI+73~)-4 939 has the transcriptional activity and can be regarded as the promoter of MSI-1 gene.A cis-acting element lies between 4 011bp to 4 939 bp upstream the transcriptional start site of(MSI-1) gene,which may be responsible for the tissue specific expression of MSI-1 gene.The cloning of MSI-1 gene promoter is a precondition for the isolation and purification of intestinal stem cells using this promoter.