Anti‐proliferative effect of rhein,an anthraquinone isolated from Cassia species,on Caco‐2 human adenocarcinoma cells

In recent years, the use of anthraquinone laxatives, in particular senna, has been associated with damage to the intestinal epithelial layer and an increased risk of developing colorectal cancer. In this study, we evaluated the cytotoxicity of rhein, the active metabolite of senna, on human colon adenocarcinoma cells (Caco‐2) and its effect on cell proliferation. Cytotoxicity studies were performed using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT), neutral red (NR) and trans‐epithelial electrical resistance (TEER) assays whereas ³H‐thymidine incorporation and Western blot analysis were used to evaluate the effect of rhein on cell proliferation. Moreover, for genoprotection studies Comet assay and oxidative biomarkers measurement (malondialdehyde and reactive oxygen species) were used. Rhein (0.1–10 μg/ml) had no significant cytotoxic effect on proliferating and differentiated Caco‐2 cells. Rhein (0.1 and 1 μg/ml) significantly reduced cell proliferation as well as mitogen‐activated protein (MAP) kinase activation; by contrast, at high concentration (10 μg/ml) rhein significantly increased cell proliferation and extracellular‐signal‐related kinase (ERK) phosphorylation. Moreover, rhein (0.1–10 μg/ml): (i) did not adversely affect the integrity of tight junctions and hence epithelial barrier function; (ii) did not induce DNA damage, rather it was able to reduce H₂O₂‐induced DNA damage and (iii) significantly inhibited the increase in malondialdehyde and reactive oxygen species (ROS) levels induced by H₂O₂/Fe²⁺. Rhein was devoid of cytotoxic and genotoxic effects in colon adenocarcinoma cells. Moreover, at concentrations present in the colon after a human therapeutic dosage of senna, rhein inhibited cell proliferation via a mechanism that seems to involve directly the MAP kinase pathway. Finally, rhein prevents the DNA damage probably via an anti‐oxidant mechanism.     

Ablation of ceramide synthase 2 exacerbates dextran sodium sulphate‐induced colitis in mice due to increased intestinal permeability

Ceramides mediate crucial cellular processes including cell death and inflammation and have recently been implicated in inflammatory bowel disease. Ceramides consist of a sphingoid long‐chain base to which fatty acids of various length can be attached. We now investigate the effect of alerting the ceramide acyl chain length on a mouse model of colitis. Ceramide synthase (CerS) 2 null mice, which lack very‐long acyl chain ceramides with concomitant increase of long chain bases and C16‐ceramides, were more susceptible to dextran sodium sulphate‐induced colitis, and their survival rate was markedly decreased compared with that of wild‐type littermates. Using mixed bone‐marrow chimeric mice, we showed that the host environment is primarily responsible for intestinal barrier dysfunction and increased intestinal permeability. In the colon of CerS2 null mice, the expression of junctional adhesion molecule‐A was markedly decreased and the phosphorylation of myosin light chain 2 was increased. In vitro experiments using Caco‐2 cells also confirmed an important role of CerS2 in maintaining epithelial barrier function; CerS2‐knockdown via CRISPR‐Cas9 technology impaired barrier function. In vivo myriocin administration, which normalized long‐chain bases and C16‐ceramides of the colon of CerS2 null mice, increased intestinal permeability as measured by serum FITC‐dextran levels, indicating that altered SLs including deficiency of very‐long‐chain ceramides are critical for epithelial barrier function. In conclusion, deficiency of CerS2 influences intestinal barrier function and the severity of experimental colitis and may represent a potential mechanism for inflammatory bowel disease pathogenesis.     

Cell wall fraction of Enterococcus hirae ameliorates TNF-alpha-induced barrier impairment in the human epithelial tight junction

Aims: The evaluation of the effects of Enterococcus hirae, an intestinal bacterium in the adjacent mucosa (mucosal bacterium), on tumour necrosis factor‐alpha (TNF‐α)‐induced barrier impairment in human epithelial Caco‐2 cells. Methods and Results: The filter‐grown Caco‐2 monolayers were used as an intestinal epithelial model system. In Caco‐2 cells, heat‐killed E. hirae ATCC 9790^T suppressed the TNF‐α‐induced barrier impairment and increase in interleukin‐8 (IL‐8) secretion, but lipase‐ and mutanolysin‐treated E. hirae ATCC 9790^T did not have these effects. It was demonstrated that lipoteichoic acid (LTA) from E. hirae ATCC 9790^T is responsible for Caco‐2 cells’ recovery from TNF‐α‐induced impairments. In addition, Caco‐2 cells had the same response to Toll‐like receptor 2 (TLR2) ligand, Pam₃Cys‐Ser‐(Lys)₄ as they did to LTA. Increased expression of zonula occludens‐1 was observed by the addition of E. hirae ATCC 9790^T to TNF‐α‐treated Caco‐2 cells, and decreased expression of myosin light chain kinase was observed by the addition of LTA and Pam₃Cys‐Ser‐(Lys)₄; this, in turn, led to barrier enforcement. Conclusions: Enterococcus hirae ATCC 9790^T cell wall fractions, such as LTA, protect against intestinal impairment by regulation of epithelial tight junction via TLR2 signalling. Significance and Impact of the Study: Enterococcus hirae could be useful in the treatment of inflammatory bowel disease, as well as other intestinal disorders.     

The human intestinal epithelial cell line Caco-2; pharmacological and pharmacokinetic applications

The gastrointestinal tract remains the most popular and acceptable route of administration for drugs. It offers the great advantage of convenience and many compounds are well absorbed and thereby provide acceptable plasma concentration-time profiles. Currently there is considerable interest from the pharmaceutical industry in development of cell culture systems that would mimic the intestinal mucosa in order to evaluate strategies for investigating and/or enhancing drug absorption. The intestinal epithelial cells of primary interest, from the standpoint of drug absorption and metabolism, are the villus cells, which are fully differentiated cells. Anin vitro cell culture system consisting of a monolayer of viable, polarized and fully differentiated villus cells, similar to that found in the small intestine, would be a valuable tool in the study of drug and nutrient transport and metabolism.The Caco-2 cell line, which exhibits a well-differentiated brush border on the apical surface and tight junctions, and expresses typical small-intestinal microvillus hydrolases and nutrient transporters, has proven to be the most popularin vitro model (a) to rapidly assess the cellular permeability of potential drug candidates, (b) to elucidate pathways of drug transport (e.g., passive versus carrier mediated), (c) to assess formulation strategies designed to enhance membrane permeability, (d) to determine the optimal physicochemical characteristics for passive diffusion of drugs, and (e) to assess potential toxic effects of drug candidates or formulation components on this biological barrier. Since differentiated Caco-2 cells express various cytochrome P450 isoforms and phase II enzymes such as UDP-glucuronosyltransferases, sulfotransferases and glutathione-S-transferases, this model could also allow the study of presystemic drug metabolism.     

SHP‐2 Phosphatase Prevents Colonic Inflammation by Controlling Secretory Cell Differentiation and Maintaining Host‐Microbiota Homeostasis

Polymorphisms in the PTPN11 gene encoding for the tyrosine phosphatase SHP‐2 were described in patients with ulcerative colitis. We have recently demonstrated that mice with an intestinal epithelial cell‐specific deletion of SHP‐2 (SHP‐2^IEC‐KO) develop severe colitis 1 month after birth. However, the mechanisms by which SHP‐2 deletion induces colonic inflammation remain to be elucidated. We generated SHP‐2^IEC‐KO mice lacking Myd88 exclusively in the intestinal epithelium. The colonic phenotype was histologically analyzed and cell differentiation was determined by electron microscopy and lysozyme or Alcian blue staining. Microbiota composition was analyzed by 16S sequencing. Results show that innate defense genes including those specific to Paneth cells were strongly up‐regulated in SHP‐2‐deficient colons. Expansion of intermediate cells (common progenitors of the Goblet and Paneth cell lineages) was found in the colon of SHP‐2^IEC‐KO mice whereas Goblet cell number was clearly diminished. These alterations in Goblet/intermediate cell ratio were noticed 2 weeks after birth, before the onset of inflammation and were associated with significant alterations in microbiota composition. Indeed, an increase in Enterobacteriaceae and a decrease in Firmicutes were observed in the colon of these mice, indicating that dysbiosis also occurred prior to inflammation. Importantly, loss of epithelial Myd88 expression inhibited colitis development in SHP‐2^IEC‐KO mice, rescued Goblet/intermediate cell ratio, and prevented NFκB hyperactivation and inflammation. These data indicate that SHP‐2 is functionally important for the maintenance of appropriate barrier function and host‐microbiota homeostasis in the large intestine. J. Cell. Physiol. 231: 2529–2540, 2016. © 2016 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc.     

Integrin α8β1 regulates adhesion,migration and proliferation of human intestinal crypt cells via a predominant RhoA/ROCK‐dependent mechanism

Background. Integrins are transmembrane αβ heterodimer receptors that function as structural and functional bridges between the cytoskeleton and ECM (extracellular matrix) molecules. The RGD (arginine‐glycine‐aspartate tripeptide motif)‐dependent integrin α8β1 has been shown to be involved in various cell functions in neuronal and mesenchymal‐derived cell types. Its role in epithelial cells remains unknown. Results. Integrin α8β1 was found to be expressed in the crypt cell population of the human intestine but was absent from differentiating and mature epithelial cells of the villus. The function of α8β1 in epithelial crypt cells was investigated at the cellular level using normal HIECs (human intestinal epithelial cells). Specific knockdown of α8 subunit expression using an shRNA (small‐hairpin RNA) approach showed that α8β1 plays important roles in RGD‐dependent cell adhesion, migration and proliferation via a RhoA/ROCK (Rho‐associated kinase)‐dependent mechanism as demonstrated by active RhoA quantification and pharmacological inhibition of ROCK. Moreover, loss of α8β1, through RhoA/ROCK, impairs FA (focal adhesion) complex integrity as demonstrated by faulty vinculin recruitment. Conclusions. Integrin α8β1 is expressed in epithelial cells. In intestinal crypt cells, α8β1 is closely involved in the regulation of adhesion, migration and cell proliferation via a predominant RhoA/ROCK‐dependent mechanism. These results suggest an important role for this integrin in intestinal crypt cell homoeostasis.     

Rotavirus infection induces cytoskeleton disorganization in human intestinal epithelial cells: implication of an increase in intracellular calcium concentration

Rotavirus infection is the most common cause of severe infantile gastroenteritis worldwide. In vivo, rotavirus exhibits a marked tropism for the differentiated enterocytes of the intestinal epithelium. In vitro, differentiated and undifferentiated intestinal cells can be infected. We observed that rotavirus infection of the human intestinal epithelial Caco-2 cells induces cytoskeleton alterations as a function of cell differentiation. The vimentin network disorganization detected in undifferentiated Caco-2 cells was not found in fully differentiated cells. In contrast, differentiated Caco-2 cells presented Ca(2+)-dependent microtubule disassembly and Ca(2+)-independent cytokeratin 18 rearrangement, which both require viral replication. We propose that these structural alterations could represent the first manifestations of rotavirus-infected enterocyte injury leading to functional perturbations and then to diarrhea.     

Colorectal Cancers Mimic Structural Organization of Normal Colonic Crypts

Colonic crypts are stereotypical structures with distinct stem cell, proliferating, and differentiating compartments. Colorectal cancers derive from colonic crypt epithelia but, in contrast, form morphologically disarrayed glands. In this study, we investigated to which extent colorectal cancers phenocopy colonic crypt architecture and thus preserve structural organization of the normal intestinal epithelium. A subset of colon cancers showed crypt-like compartments with high WNT activity and nuclear β-Catenin at the leading tumor edge, adjacent proliferation, and enhanced Cytokeratin 20 expression in most differentiated tumor epithelia of the tumor center. This architecture strongly depended on growth conditions, and was fully reproducible in mouse xenografts of cultured and primary colon cancer cells. Full crypt-like organization was associated with low tumor grade and was an independent prognostic marker of better survival in a collection of 221 colorectal cancers. Our findings suggest that full activation of preserved intestinal morphogenetic programs in colon cancer requires in vivo growth environments. Furthermore, crypt-like architecture was linked with less aggressive tumor biology, and may be useful to improve current colon cancer grading schemes.     

Live Faecalibacterium prausnitzii in an apical anaerobic model of the intestinal epithelial barrier

Faecalibacterium prausnitzii, an abundant member of the human commensal microbiota, has been proposed to have a protective role in the intestine. However, it is an obligate anaerobe, difficult to co‐culture in viable form with oxygen‐requiring intestinal cells. To overcome this limitation, a unique apical anaerobic model of the intestinal barrier, which enabled co‐culture of live obligate anaerobes with the human intestinal cell line Caco‐2, was developed. Caco‐2 cells remained viable and maintained an intact barrier for at least 12 h, consistent with gene expression data, which suggested Caco‐2 cells had adapted to survive in an oxygen‐reduced atmosphere. Live F. prausnitzii cells, but not ultraviolet (UV)‐killed F. prausnitzii, increased the permeability of mannitol across the epithelial barrier. Gene expression analysis showed inflammatory mediators to be expressed at lower amounts in Caco‐2 cells exposed to live F. prausnitzii than UV‐killed F. prausnitzii, This, consistent with previous reports, implies that live F. prausnitzii produces an anti‐inflammatory compound in the culture supernatant, demonstrating the value of a physiologically relevant co‐culture system that allows obligate anaerobic bacteria to remain viable.     

MicroRNA‐21 regulates intestinal epithelial tight junction permeability

Increased tight junction (TJ) barrier permeability, induced by tumour necrosis factor (TNF)‐α, may lead to the defects in TJ barrier and subsequent development of inflammation. Recent evidence suggests that miR‐21 is implicated in inflammatory diseases. However, the physiological role of miR‐21 in intestinal permeability remains elusive. This study aimed to explore the role of miR‐21 in intestinal epithelial tight junction permeability. The filter‐grown Caco‐2 monolayers model system was established to mimic intestinal barrier defect. The tight junction proteins were detected by immunofluorescence and western blot analysis. The expression of miR‐21 was assessed by real‐time polymerase chain reaction (PCR). We found that the expression of miR‐21 was increased significantly in TNF‐α induced intestinal TJ barrier defect model. miR‐21 overexpression significantly enhanced while miR‐21 knockdown significantly decreased intestinal permeability. In addition, miR‐21 overexpression significantly increased while miR‐21 knockdown significantly decreased the levels of interleukin‐6, interleukin‐8 and prostaglandin E2 in cell culture medium. Furthermore, miR‐21 positively regulated Akt phosphorylation and negatively regulated Phosphatase and tensin homolog (PTEN) expression in Caco‐2 cells. Our results suggest that miR‐21 may regulate intestinal epithelial tight junction permeability through PTEN/PI3K/Akt signalling pathway. This promotes the feasibility of targeting miR‐21 in the clinical to preserve the intestinal barrier. Copyright © 2015 John Wiley & Sons, Ltd.     

Structural and molecular insights into novel surface‐exposed mucus adhesins from Lactobacillus reuteri human strains

The mucus layer covering the gastrointestinal tract is the first point of contact of the intestinal microbiota with the host. Cell surface macromolecules are critical for adherence of commensal bacteria to mucus but structural information is scarce. Here we report the first molecular and structural characterization of a novel cell‐surface protein, Lar_0958 from Lactobacillus reuteri JCM 1112^T, mediating adhesion of L. reuteri human strains to mucus. Lar_0958 is a modular protein of 133 kDa containing six repeat domains, an N‐terminal signal sequence and a C‐terminal anchoring motif (LPXTG). Lar_0958 homologues are expressed on the cell‐surface of L. reuteri human strains, as shown by flow‐cytometry and immunogold microscopy. Adhesion of human L. reuteri strains to mucus in vitro was significantly reduced in the presence of an anti‐Lar_0958 antibody and Lar_0958 contribution to adhesion was further confirmed using a L. reuteri ATCC PTA 6475 lar_0958 KO mutant (6475‐KO). The X‐ray crystal structure of a single Lar_0958 repeat, determined at 1.5 Å resolution, revealed a divergent immunoglobulin (Ig)‐like β‐sandwich fold, sharing structural homology with the Ig‐like inter‐repeat domain of internalins of the food borne pathogen Listeria monocytogenes. These findings provide unique structural insights into cell‐surface protein repeats involved in adhesion of Gram‐positive bacteria to the intestine.     

Regulation of intestinal stem cells in mammals and Drosophila

The digestive systems in mammals and Drosophila are quite different in terms of their complexity and organization, but their biological functions are similar. The Drosophila midgut is a functional equivalent of the mouse small intestine. Adult intestinal stem cells (ISCs) have been identified in both the mouse small intestine and Drosophila midgut. The anatomy and cell renewal in the Drosophila midgut are similar to those in the mouse small intestine: the intestinal epithelium in both systems is a tube composed of epithelial cells with absorptive and secretory functions; the Notch signaling controls absorptive versus secretory fate decisions in the intestinal epithelium; cell renewal in both systems starts from stem cells in the basal cell layer, and the differentiated cells then move toward the lumen. However, it is clear that the stem cells in the two systems are regulated in different ways. In this review, we will compare cell renewal and stem cell regulation in the two systems. J. Cell. Physiol. 222:33–37, 2010. © 2009 Wiley‐Liss, Inc.     

Caenorhabditis is a metazoan host for Legionella

We investigated whether nematodes contribute to the persistence, differentiation and amplification of Legionella species in soil, an emerging source for Legionnaires' disease. Here we show that Legionella spp. colonize the intestinal tracts of Caenorhabditis nematodes leading to worm death. Susceptibility to Legionella is influenced by innate immune responses governed by the p38 mitogen‐activated protein kinase and insulin/insulin growth factor‐1 receptor signalling pathways. We also show that L. pneumophila colonizes the intestinal tract of nematodes cultivated in soil. To distinguish between transient infection and persistence, plate‐fed and soil‐extracted nematodes‐fed fluorescent strains of L. pneumophila were analysed. Bacteria replicated within the nematode intestinal tract, did not invade surrounding tissue, and were excreted as differentiated forms that were transmitted to offspring. Interestingly, the ultrastructural features of the differentiated bacterial forms were similar to cyst‐like forms observed within protozoa, amoeba and mammalian cell lines. While intestinal colonization of L. pneumophila dotA and icmT mutant strains did not alter the survival rate of nematodes in comparison to wild‐type strains, nematodes colonized with the dot/icm mutant strains exhibited significantly increased levels of germline apoptosis. Taken together, these studies show that nematodes may serve as natural hosts for these organisms and thereby contribute to their dissemination in the environment and suggest that the remarkable ability of L. pneumophila to subvert host cell signalling and evade mammalian immune responses evolved through the natural selection associated with cycling between protozoan and metazoan hosts.     

The c‐MYC‐ABCB5 axis plays a pivotal role in 5‐fluorouracil resistance in human colon cancer cells

c‐MYC overexpression is frequently observed in various cancers including colon cancer and regulates many biological activities such as aberrant cell proliferation, apoptosis, genomic instability, immortalization and drug resistance. However, the mechanism by which c‐MYC confers drug resistance remains to be fully elucidated. In this study, we found that the c‐MYC expression level in primary colorectal cancer tissues correlated with the recurrence rate following 5‐fluorouracil (5‐FU)‐based adjuvant chemotherapy. Supporting this finding, overexpression of exogenous c‐MYC increased the survival rate following 5‐FU treatment in human colon cancer cells, and knockdown of endogenous c‐MYC decreased it. Furthermore, c‐MYC knockdown decreased the expression level of ABCB5, which is involved in 5‐FU resistance. Using a chromatin immunoprecipitation assay, we found that c‐MYC bound to the ABCB5 promoter region. c‐MYC inhibitor (10058‐F4) treatment inhibited c‐MYC binding to the ABCB5 promoter, leading to a decrease in ABCB5 expression level. ABCB5 knockdown decreased the survival rate following 5‐FU treatment as expected, and the ABCB5 expression level was increased in 5‐FU‐resistant human colon cancer cells. Finally, using a human colon cancer xenograft murine model, we found that the combined 5‐FU and 10058‐F4 treatment significantly decreased tumorigenicity in nude mice compared with 5‐FU or 10058‐F4 treatment alone. 10058‐F4 treatment decreased the ABCB5 expression level in the presence or absence of 5‐FU. In contrast, 5‐FU treatment alone increased the ABCB5 expression level. Taken together, these results suggest that c‐MYC confers resistance to 5‐FU through regulating ABCB5 expression in human colon cancer cells.     

Oxygen and contact with human intestinal epithelium independently stimulate virulence gene expression in enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) are important intestinal pathogens causing acute and persistent diarrhoeal illness worldwide. Although many putative EAEC virulence factors have been identified, their association with pathogenesis remains unclear. As environmental cues can modulate bacterial virulence, we investigated the effect of oxygen and human intestinal epithelium on EAEC virulence gene expression to determine the involvement of respective gene products in intestinal colonisation and pathogenesis. Using in vitro organ culture of human intestinal biopsies, we established the colonic epithelium as the major colonisation site of EAEC strains 042 and 17‐2. We subsequently optimised a vertical diffusion chamber system with polarised T84 colon carcinoma cells for EAEC infection and showed that oxygen induced expression of the global regulator AggR, aggregative adherence fimbriae, E. coli common pilus, EAST‐1 toxin, and dispersin in EAEC strain 042 but not in 17‐2. Furthermore, the presence of T84 epithelia stimulated additional expression of the mucinase Pic and the toxins HlyE and Pet. This induction was dependent on physical host cell contact and did not require AggR. Overall, these findings suggest that EAEC virulence in the human gut is modulated by environmental signals including oxygen and the intestinal epithelium.     

Generation and characterization of DSPP‐Cerulean/DMP1‐Cherry reporter mice

To gain a better understanding of the progression of progenitor cells in the odontoblast lineage, we have examined and characterized the expression of a series of GFP reporters during odontoblast differentiation. However, previously reported GFP reporters (pOBCol2.3‐GFP, pOBCol3.6‐GFP, and DMP1‐GFP), similar to the endogenous proteins, are also expressed by bone‐forming cells, which made it difficult to delineate the two cell types in various in vivo and in vitro studies. To overcome these difficulties we generated DSPP‐Cerulean/DMP1‐Cherry transgenic mice using a bacterial recombination strategy with the mouse BAC clone RP24‐258g7. We have analyzed the temporal and spatial expression of both transgenes in tooth and bone in vivo and in vitro. This transgenic animal enabled us to visualize the interactions between odontoblasts and surrounding tissues including dental pulp, ameloblasts and cementoblasts. Our studies showed that DMP1‐Cherry, similar to Dmp1, was expressed in functional and fully differentiated odontoblasts as well as osteoblasts, osteocytes and cementoblasts. Expression of DSPP‐Cerulean transgene was limited to functional and fully differentiated odontoblasts and correlated with the expression of Dspp. This transgenic animal can help in the identification and isolation of odontoblasts at later stages of differentiation and help in better understanding of developmental disorders in dentin and odontoblasts.     

Insights into amebiasis using a human 3D‐intestinal model

Entamoeba histolytica is the causative agent of amebiasis, an infectious disease targeting the intestine and the liver in humans. Two types of intestinal infection are caused by this parasite: silent infection, which occurs in the majority of cases, and invasive disease, which affects 10% of infected persons. To understand the intestinal pathogenic process, several in vitro models, such as cell cultures, human tissue explants or human intestine xenografts in mice, have been employed. Nevertheless, our knowledge on the early steps of amebic intestinal infection and the molecules involved during human–parasite interaction is scarce, in part due to limitations in the experimental settings. In the present work, we took advantage of tissue engineering approaches to build a three‐dimensional (3D)‐intestinal model that is able to replicate the general characteristics of the human colon. This system consists of an epithelial layer that develops tight and adherens junctions, a mucus layer and a lamina propria‐like compartment made up of collagen containing macrophages and fibroblast. By means of microscopy imaging, omics assays and the evaluation of immune responses, we show a very dynamic interaction between E. histolytica and the 3D‐intestinal model. Our data highlight the importance of several virulence markers occurring in patients or in experimental models, but they also demonstrate the involvement of under described molecules and regulatory factors in the amoebic invasive process.     

Homeosis and polyposis: A tale from the mouse

Homeobox genes play essential roles in specifying the fates of different cell types during embryogenesis. In Drosophila, the homeotic gene caudal is important for the generation of posterior structures. In the mouse, the caudal homologue Cdx2 has been implicated in directing early processes in intestinal morphogenesis and in the maintenance of the differentiated phenotype. A recent study showed that Cdx2 null mutation was embryonically lethal, whereas Cdx2^+/? mice developed multiple intestinal polyps in the proximal colon in addition to developmental defects⁽¹⁾. There are striking phenotypic similarities and differences between Cdx2^+/? and other mice predisposed to intestinal neoplasia. The possible role of Cdx2 in human colorectal tumorigenesis is discussed.     

Cryptosporidium parvum increases intestinal permeability through interaction with epithelial cells and IL‐1β and TNFα released by inflammatory monocytes

Intestinal epithelial cells form a single layer separating the intestinal lumen containing nutriments and microbiota from the underlying sterile tissue and therefore play a key role in maintaining homeostasis. We investigated the factors contributing to the alteration of the epithelial barrier function during Cryptosporidium parvum infection. Infected polarized epithelial cell monolayers exhibit a drop in transepithelial resistance associated with a delocalization of E‐cadherin and β‐catenin from their intercellular area of contact, the adherens junction complex. In neonatal mice infected by C. parvum, the increased permeability is correlated with parasite development and with an important recruitment of Ly6c⁺ inflammatory monocytes to the subepithelial space. TNFα and IL‐1β produced by inflammatory monocytes play a key role in the loss of barrier function. Our findings demonstrate for the first time that both the parasite and inflammatory monocytes contribute to the loss of intestinal barrier function during cryptosporidiosis.