Epithelial-Connective Tissue Cross-Talk Is Essential for Regeneration of Intestinal Epithelium

Regulation of Shh/Bmp4 Signaling Pathway by DNA Methylation in Rectal Nervous System Development of Fetal Rats with Anorectal Malformation

OBJECTIVE

To study the influence of gene methylation in the Shh/Bmp4 signaling pathway on the enteric nervous system in the rectum of rat embryos with anorectal malformations (ARMs).

METHODS

Pregnant Sprague Dawley rats were divided into three groups; two groups treated with either ethylene thiourea (ETU induce ARM) or ETU+5-azacitidine (5-azaC inhibit DNA methylation) and a normal control group. The levels of DNA methyltransferases (DNMT1, DNMT3a, DNMT3b), the methylation status of the Shh gene promoter region and the expression of the key components were detected by PCR, immunohistochemistry and western blotting.

RESULTS

The expression of DNMTs in the rectal tissue of the ETU and ETU+5-azaC groups was higher than that of the control. The expression of DNMT1, DNMT3a and methylation level of the Shh gene promoter in the ETU group was higher than in the ETU+5-azaC group (P < 0.01). The methylation level of the Shh gene promoter was higher in the ETU+5-azaC group than in the control. The Shh and Bmp4 expression in the ETU and ETU+5-azaC groups were lower than in the control, and their expression in the ETU group was also lower than in the ETU+5-azaC group.

CONCLUSION

The methylation status of genes in the rectum of the ARM rat model may be changed by intervention. The low methylation level of the Shh gene may promote the expression of key Shh/Bmp4 signaling pathway components.

Altered epithelial barrier functions in the colon of patients with spina bifida

Our objectives were to better characterize the colorectal function of patients with Spina Bifida (SB). Patients with SB and healthy volunteers (HVs) completed prospectively a standardized questionnaire, clinical evaluation, rectal barostat, colonoscopy with biopsies and faecal collection. The data from 36 adults with SB (age: 38.8 [34.1-47.2]) were compared with those of 16 HVs (age: 39.0 [31.0-46.5]). Compared to HVs, rectal compliance was lower in patients with SB (p = 0.01), whereas rectal tone was higher (p = 0.0015). Ex vivo paracellular permeability was increased in patients with SB (p = 0.0008) and inversely correlated with rectal compliance (r = - 0.563, p = 0.002). The expression of key tight junction proteins and inflammatory markers was comparable between SB and HVs, except for an increase in Claudin-1 immunoreactivity (p = 0.04) in SB compared to HVs. TGFβ1 and GDNF mRNAs were expressed at higher levels in patients with SB (p = 0.02 and p = 0.008). The levels of acetate, propionate and butyrate in faecal samples were reduced (p = 0.04, p = 0.01, and p = 0.02, respectively). Our findings provide evidence that anorectal and epithelial functions are altered in patients with SB. The alterations in these key functions might represent new therapeutic targets, in particular using microbiota-derived approaches.Clinical Trials: NCT02440984 and NCT03054415.

Low lethal doses of Streptococcus iniae caused enteritis in Siberian sturgeon (Acipenser baerii)

In aquaculture, the incidence of enteritis due to Streptococcus iniae infection in Siberian sturgeon (Acipenser baerii) has increased in recent years. The pathogenesis of S. iniae is largely unknown due to the paucity of experimental studies on fish intestinal inflammation. In this study, S. iniae infection of A. baerii juveniles was induced by anal intubation of 0.15 mL at a low lethal dose (2 × 10⁷ CFU/mL). Intestinal pathology and gene expression studies were conducted within 10 days of the experiment. Histopathological examination showed severe intestinal lesions, inflammatory cell infiltration, intestinal submucosa edema, epithelial cell shedding and necrosis. Predominant symptoms of exudative inflammation, metamorphic inflammation and proliferative inflammation on days 1-3, 4-6, and 7-10 post infection were shown, respectively. Ultrastructural observations also revealed fractured microvilli and shedding on days 4-6. Intestinal villi gradually repaired during the subsequent 7-10 days post infection. Expression of the pro-inflammatory cytokines, tumor necrosis factor and interleukin 1β were up-regulated on days 1-3 followed by a significant decrease on day 5, ultimately reaching control levels on day 10 post infection. A similar pattern was shown in mucus cells, involving mucin secretion and expression of the mucin encoding gene, Mucin-2. These results showed the cellular response to S. iniae infection associated with inflammatory genes expression in the Siberian sturgeon.

Origin and maintenance of the intestinal cancer stem cell

Colorectal cancer is one of the most common cancers in the western world and its incidence is steadily increasing. Understanding the basic biology of both the normal intestine and of intestinal tumorigenesis is vital for developing appropriate and effective cancer therapies. However, relatively little is known about the normal intestinal stem cell or the hypothetical intestinal cancer stem cell, and there is much debate surrounding these areas. This review briefly describes our current understanding of the properties of both the intestinal stem cell and the intestinal cancer stem cell. We also discuss recent theories regarding the origin of the intestinal cancer stem cell, and the signals required for its maintenance and proliferation. Finally, we place the relevance of cancer stem cell research into context by discussing potential clinical applications of targeting the intestinal cancer stem cell.

Co-culture of intestinal epithelial and stromal cells in 3D collagen-based environments

AIM

To investigate the co-culture of established intestinal epithelial cell lines and stromal cells in a series of collagen-based environments for production of tissue-engineered intestinal epithelium for in vitro investigations.

MATERIALS & METHODS

Intestinal epithelial cells were co-cultured with fibroblasts on a range of supporting collagen matrices including commercially available Promogran and on collagen-based gels.

RESULTS

Epithelial growth was achieved with one combination of vimentin-expressing stromal and cytokeratin-expressing intestinal epithelial cells grown on collagen gels supplemented with Matrigel, and held at an air-liquid interface.

CONCLUSIONS

Collagen-based gels can support the co-culture of intestinal epithelial and stromal cells resulting in the growth of an epithelium that has some morphological similarity to normal intestinal tissue.

Acid, bile, and CDX: the ABCs of making Barrett's metaplasia

Barrett's esophagus, a squamous-to-columnar cell metaplasia that develops as a result of chronic gastroesophageal reflux disease (GERD), is a risk factor for esophageal adenocarcinoma. The molecular events underlying the pathogenesis of Barrett's metaplasia are poorly understood, but recent studies suggest that interactions among developmental signaling pathways, morphogenetic factors, and Caudal homeobox (Cdx) genes play key roles. Strong expression of Cdx genes normally is found in the intestine but not in the esophagus and stomach. When mice are genetically engineered so that their gastric cells express Cdx, the stomach develops a metaplastic, intestinal-type epithelium similar to that of Barrett's esophagus. Exposure to acid and bile has been shown to activate the Cdx promoter in certain esophageal cell lines, and Cdx expression has been found in inflamed esophageal squamous epithelium and in the specialized intestinal metaplasia of Barrett's esophagus. Barrett's metaplasia must be sustained by stem cells, which might be identified by putative, intestinal stem cell markers like leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and doublecortin and CaM kinase-like-1 (DCAMKL-1). Emerging concepts in tumor biology suggest that Barrett's cancers may develop from growth-promoting mutations in metaplastic stem cells or their progenitor cell progeny. This report reviews the roles of developmental signaling pathways and the Cdx genes in the development of normal gut epithelia and the potential mechanisms whereby GERD may induce the esophageal expression of Cdx genes and other morphogenetic factors that mediate the development of Barrett's metaplasia. The role of stem cells in the development of metaplasia and in carcinogenesis and the potential for therapies directed at those stem cells also is addressed.

Novel findings in the pathogenesis of esophageal columnar metaplasia or Barrett's esophagus

PURPOSE OF REVIEW

In esophageal metaplasia the transdifferentiation of the epithelium is the result of longstanding gastroesophageal reflux disease that causes inflammation of the esophageal squamous mucosa, and occasionally is followed by replacement of the squamous epithelium by a columnar type of mucosa. For a long time, the molecular mechanisms involved in metaplasia were poorly understood. This review focuses on several recent findings on the molecular mechanisms involved in esophageal columnar metaplasia.

RECENT FINDINGS

Our recent findings on bone morphogenetic protein 4 and other recent discoveries in the field of cell signaling that take place during the sequence of inflammation and epithelial transdifferentiation are highlighted. In this process, several embryonic pathways that were silenced in the adult esophagus, and factors that are normally involved in the homeostasis of the large intestine, seem to be induced. These factors may mediate transdifferentiation of the esophageal epithelium.

SUMMARY

Although there are many aspects that need further investigation, it seems that in columnar metaplasia of the esophagus inductive morphogenes such as bone morphogenetic protein 4 are important for development and differentiation. Development of specialized intestinal type of metaplasia is the result of a succession of events, in which the effect of stromal factors is followed by expression of intestine-specific factors.

Intestinal homeostasis and neoplasia studied using conditional transgenesis

Constitutive mouse models of intestinal neoplasia, such as the Apc(min/+) (multiple intestinal neoplasia) mouse have proven valuable tools both for furthering our understanding of tumorigenesis and for the development of therapeutic strategies. However, the in vivo study of a number of genes has been precluded by their absolute requirement during embryonic development. This has led to the development of conditional strategies that allow gene regulation in vivo. This review describes the principal techniques used to achieve conditional transgenesis within the mouse intestine, with a particular focus upon the Cre-Lox and Tet-regulable systems. Further, we discuss how these techniques are being used to dissect the mechanisms governing both normal homeostasis and neoplastic development within the intestine.

Matrix metalloproteinases in inflammatory bowel disease: boon or a bane?

Matrix metalloproteinases (MMPs) are a family of Zn(2+)-dependent extracellular matrix (ECM) degrading endopeptidases that share common functional domains, activation mechanisms, and collectively have the capacity to degrade all types of ECM proteins. In addition to playing a central role in ECM turnover, MMPs proteolytically activate or degrade a variety of nonmatrix substrates including chemokines, cytokines, growth factors, and junctional proteins. Thus, they are increasingly recognized as critical players in inflammatory response. Indeed, accumulating data from several studies indicate that they are the predominant proteases involved in the pathogenesis of inflammatory bowel disease (IBD) via their influence on the function and migration of inflammatory cells, mucosal ulceration, as well as matrix deposition and degradation. Some MMPs are constitutively expressed and play a protective role in IBD through their effect on cellular homeostasis, while others are induced during inflammation-mediated tissue damage. This article focuses on the role of the various MMPs in IBD, discussing their physiologic and pathogenetic role in the context of intestinal defense, mucosal inflammatory response, and immune cell-epithelial interaction.

Regulating MHC expression for cellular therapeutics

BACKGROUND

In the past decade, regenerative medicine and cell-based therapies have emerged as new science and technology, with the main goal of repairing, replacing, or regenerating new tissues. A critical issue in this field is the high polymorphism of HLA, which compromises immune acceptance. The lentivirus-mediated delivery of short-hairpin RNAs (shRNAs) has proved to be an efficient method to inhibit the translation of a specific gene.

STUDY DESIGN AND METHODS

A lentiviral-based vector system was used for drug-inducible expression of shRNA sequences that target either beta2-microglobulin (beta2m) or HLA heavy-chain transcripts.

RESULTS

The transduction of inducible RNA interference cassettes containing the sequences for shRNAs targeting beta2m or HLA heavy chain suppressed HLA class I expression by up to 90 percent in HeLa and B-lymphocyte cell lines as well as in peripheral blood monocytes. The expression of HLA class I antigens was fully restored in these cells after the drug had been discontinued. It was demonstrated that HLA class I knockdown was effective in preventing antibody-mediated cell lysis and CD8+ T-cell response. The residual HLA expression in HLA-silenced cells may provide sufficient protection against natural killer cell-mediated lysis.

CONCLUSIONS

These data demonstrate the feasibility of controlling HLA expression by genetically modifying cell-based therapeutics to overcome the limitations of immune rejection, bringing cellular therapies closer to reality.