Role of Notch signalling in intestinal epithelium

Résumé: Chez les mammifères, les intestins sont les organes ayant le plus haut taux de renouvellement cellulaire dans l'organisme. L'épithélium intestinal se renouvelle complètement en moins d'une semaine. Il se compose de projections (villosités) et d'invaginations (cryptes) qui ont toutes deux des fonctions bien distinctes. Les cellules de l'intestin sont constamment produites à partir de cellules souches, situées dans la crypte, qui se différencient en cellules proliférantes transitoires, puis en cellules caliciformes, de Paneth, entéroendocrine ou en entérocytes. Ces cellules migrent dans leurs lieux spécifiques pour accomplir leur fonction physiologique pour finalement mourir. A cours de mon travail de thèse, j'ai étudié le rôle de la voie de signalisation de Notch dans le renouvellement cellulaire et dans le processus de l'homéostase des cellules de l'intestin marin en utilisant le système Cre-loxP pour induire la délétion des gènes Notch1, Notch2, Jaggedl et RBP-Jk. Bien que l'inactivation de Notch1 avec ou sans Jagged1, ou celle de Notch2, n'aboutissent à aucun phénotype, une déficience pour RBP-Jk, ou pour Notch1 et Notch2 simultanément, conduit au développement d'un impressionnant phénotype. Au niveau de la crypte, une rapide et importante modification des cellules apparaît: les cellules proliférantes sont devenues des cellules caliciformes qui ont perdu la capacité de se renouveler. Ces résultats impliquent la voie Notch en tant que nouvelle clé de voûte dans le maintien des cellules qui s'auto-renouvellent dans l'épithélium intestinal. Un rôle similaire a été proposé pour la voie Wnt, laquelle n'est cependant, pas affectée dans nos souris. C'est pourquoi ces deux voies sont essentielles dans le maintien de la prolifération dans les cryptes intestinales. Ce travail a aussi proposé un mécanisme par lequel la voie Notch contrôlerait l'intégrité du cycle cellulaire dans les cellules de la crypte intestinale, ceci en inhibant la transcription d'un inhibiteur du cycle cellulaire, la protéine p27KIP1. De plus, l'inactivation de RBP-Jk dans les adénomes développés par les souris APCmin induisent la différenciation de cellules tumorales en cellules caliciformes. Comme autre effet, la localisation histologique des cellules de Paneth est également affectée par la délétion de RBP-Jk ou de Notch1/Notch2, suggérant un rôle pour la voie Notch dans le compartiment des cellules de Paneth. Finalement, ce travail démontre que les cellules progénitrices de l'intestin ont besoin d'une convergence fonctionnelle des voie Wnt et Notch. Ces résultats préliminaires peuvent être considérés comme un concept pour l'utilisation d'inhibiteurs de secrétase-γ (inhibiteurs de Notch) à des fins thérapeutiques pour les cancers colorectaux. Summary The mammalian intestine has one of the highest cellular turnover rates in the body. The complete intestinal epithelium is renewed in less than a week. It is divided into spatially distinct compartments in the form of finger-like projections (villi) and flask-shaped invaginations (crypts) that are dedicated to specific functions. Intestinal cells are constantly produced from a stem cell reservoir that gives rise to proliferating transient amplifying cells, which subsequently differentiate and home to their specific compartments before dying after having fulfilled their physiological function. In this thesis project, the physiological role of the Notch signalling cascade in the marine intestine was studied. Inducible tissue specific inactivation of Notch1, Notch2, Jagged1 and RBP-Jk genes was applied to assess their role in the maintenance of intestinal homeostasis and cell fate determination. The analysis unequivocally revealed that Notch1, Notch1 and Jagged1 combined as well as Notch2 are dispensable for intestinal homeostasis and lineage differentiation. However, deficiency of RBP-Jk as well as the simultaneous inactivation of both Notch1 and Notch2 receptors unveiled a striking phenotype. In these mice, a rapid and massive conversion of proliferative crypt cells into post-mitotic goblet cells was observed. These results identify the Notch pathway as a key player for the maintenance of the proliferative crypt compartment. A similar role was implicated for the Wnt cascade, which, however, was not affected in the different tissue specific Notch signalling deficient mice. Thus, the Wnt and Notch signalling pathways are essential for the self-renewal capacity of the intestinal epithelium. Furthermore, our results suggest a molecular mechanism for Notch signalling mediated control of cell cycle regulation within the crypt. The Notch cascade inhibits expression of the cyclin-dependent kinase inhibitor p27KIP1 and thereby maintains proliferation of the intestinal progenitor cells. In addition, the inactivation of RBP-Jk in adenomas developed by APCmin mice resulted in the differentiation of tumour cells into goblet cells. Finally, Notch deficiency affected differentiated Paneth cells, suggesting that Notch may play a role in the Paneth cell compartment. In summary, this work clearly demonstrates that undifferentiated, proliferative cells in intestinal crypts require the concerted activation of the RBP-Jk-mediated Notch signalling and the Wnt cascade. In addition, our preliminary results can be considered as a "proof-of-principle" for the use of γ-secretase inhibitors for therapeutic modalities for colorectal cancer.

Documento de salud infantil

2ª edición publicada en 2014: http://www.repositoriosalud.es/handle/10668/1758

Dietoterapia en paciente con linfangiectasia intestinal primaria y ascitis quilosa de repetición.

OBJECTIVES Primary intestinal lymphangiectasia is a lymphatic system's disorder, where lymphatic drainage is blockaged. Clinically it produces malabsorption, protein-losing enteropathy, hypogammaglobulin in blood, and several degrees of malnutrition. Its treatment is not easy and includes dietetic-therapy and drugs. MATERIAL AND METHOD A 35-year-old-woman case report is exposed. She has recurrent chylosa ascites, requiring several admissions and evacuatory paracentesis. After food-fat was replaced by medium-chain triacyl-glicerol-enriched diet, a clinical, analytical and anthropometric improvement was demonstrated. CONCLUSIONS The major way of treatment in intestinal lymphangiectasia in this case is the employement of specific-diet and adaptaded-basic-food. It's difficult and high collaboration of the patient is required, being necessary medical revisions during the whole life, due to the not well known evolution of this long-standing disease.

Validation and clinical use of the CECA, a disease-specific quality of life questionnaire for patients with anogenital Condylomata Acuminata

The aim of this validation study was to assess the measurement properties of the CECA (Spanish acronym for the Specific Questionnaire for Condylomata Acuminata) in patients with anogenital condylomas. A total of 247 patients aged > 18 years completed the questionnaire on 2 occasions as well as the Dermatology Life Quality Index (DLQI). The CECA questionnaire showed good internal consistency (Cronbach's alpha values of 0.86 and 0.91 in the emotional and sexual activity dimensions) and good testretest reliability (intraclass correlation coefficient 0.76 emotional dimension, 0.82 sexual activity dimension). Patients with de novo lesions and those with more extensive lesions and larger number of warts showed poorer health-related quality of life. CECA and DLQI scores correlated moderately. Patients whose lesions cleared at follow-up or with a reduction of >or= 50% showed a better improvement of health-related quality of life. The CECA questionnaire is a valid, reliable and sensitive tool for the assessment of health-related quality of life in patients with anogenital warts.

Reseccion intestinal masiva. Proceso de adaptacion nutricional

INTRODUCTION Massive small bowel resection (MSBR) with a remnant jejunum shorter than 60 cm produces severe water, electrolytes, vitamins and protein-caloric depletion. While waiting for a viable intestinal transplantation, most of MSBR patients depend on total parenteral nutrition (TPN). CLINICAL CASE 32 years old male, with MSBR due to sectioning trauma of the superior mesenteric artery root. First surgical intervention: jejunostomy with small bowel, right colon, and spleen resection. Six months later: jejunocolic anastomosis with 12-cm long jejunum remnant and prophylactic cholecystectomy. NUTRITIONAL INTERVENTION: 1st phase. Hemodynamic stabilization and enteral stimulation (6 months): TPN + enteral nutrition with elemental formula + oral glucohydroelectrolitic solution (OGHS) + 15 g/d of oral glutamine + omeprazol. Clinical course indicators: biochemistry, I/L balance. 2a phase. Digestive adaptation with colonic integration (8 months): replacement of TPN by part-time peripheral PN. Progressive cooked diet complemented with pancreatic poly-enzyme preparation, omeprazol, OGHS, glutamine, elemental formula. Clinical course indicators: biochemistry, diuresis, weight and feces. 3a phase. Auto-sufficiency without parenteral dependence: fragmented free oral diet supplemented with pancreatic poly-enzyme preparation, mineralized beverages, enteral formula supplement, Ca and Mg oral supplements, oral multivitamin and mineral preparation, monthly IM vitamin B12. Current situation actual (52 months): slight ponderal gain, diuresis > liter/day, 2-3 normal feces, no clinical signs of any deficiency and normal blood levels of micronutrients. CONCLUSION It may be possible to withdraw from PN in MSBR considering, as in this case, favorable age and etiology and early implementation of an appropriate protocol of remnant adaptation.

Resección intestinal masiva: Proceso de adaptación intestinal.

Carta al Director de J. M. Moreno Villares, sobre el artículo: Leyva Martínez S, Fernández Lloret S, Martín Ruiz JL. Resección intestinal masiva. Proceso de adaptación intestinal. Nutr Hosp 2007; 22:616-20; y réplica de los autores (Leyva Martínez S).

Is the RET proto-oncogene involved in the pathogenesis of intestinal neuronal dysplasia type B?

Hirschsprung disease (HSCR) is defined by the absence of intramural ganglia of Meissner and Auerbach along variable lengths of the gastrointestinal tract. Intestinal neuronal dysplasia (IND) type B is characterized by the malformation of the parasympathetic submucous plexus of the gut. A connection appears to exist between these two enteric nervous system abnormalities. Due to the major role played by the RET proto-oncogene in HSCR, we sought to determine whether this gene was also related to INDB. dHPLC techniques were employed to screen the RET coding region in 23 patients presenting with INDB and 30 patients with a combined HSCR+INDB phenotype. In addition, eight RET single nucleotide polymorphisms (SNPs) were strategically selected and genotyped by TaqMan technology. The distribution of SNPs and haplotypes was compared among the different groups of patients (INDB, HSCR+INDB, HSCR) and the controls. We found several RET mutations in our patients and some differences in the distribution of the RET SNPs among the groups of study. Our results suggest an involvement of RET in the pathogenesis of intestinal INDB, although by different molecular mechanisms than those leading to HSCR. Further investigation is warranted to elucidate these precise mechanisms and to clarify the genetic nature of INDB.

Tratamiento nutricional del fallo intestinal y potenciales mecanismos de estimulación.

Severe forms of intestinal failure represent one of the most complex pathologies to manage, in both children and adults. In adults, the most common causes are chronic intestinal pseudo-obstruction and severe short bowel syndrome following large intestinal resections, particularly due to massive mesenteric ischemic, within the context of cardiopathies occurring with atrial fibrillation. The essential management after stabilizing the patient consists in nutritional support, either by parenteral or enteral routes, with tolerance to oral diet being the final goal of intestinal adaptation in these pathologies. Surgery may be indicated in some cases to increase the absorptive surface area. Parenteral nutrition is an essential support measure that sometimes has to be maintained for long time, even forever, except for technique-related complications or unfavorable clinical course that would lead to extreme surgical alternatives such as intestinal transplantation. Hormonal therapy with trophism-stimulating factors opens new alternatives that are already being tried in humans.

Results of the 2nd scientific workshop of the ECCO (III): basic mechanisms of intestinal healing.

The second scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal healing for the disease course of inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms, markers for disease prediction, detection and monitoring of intestinal healing, impact of intestinal healing on the disease course of IBD as well as therapeutic strategies. The results of this workshop are presented in four separate manuscripts. This section describes basic mechanisms of intestinal healing, identifies open questions in the field and provides a framework for future studies.

Inhibitory receptors specific for MHC class I educate murine NK cells but not CD8αα intestinal intraepithelial T lymphocytes.

The engagement of inhibitory receptors specific for major histocompatibility complex class I (MHC-I) molecules educates natural killer (NK) cells, meaning the improvement of the response of activation receptors to subsequent stimulation. It is not known whether inhibitory MHC-I receptors educate only NK cells or whether they improve the responsiveness of all cell types, which express them. To address this issue, we analyzed the expression of inhibitory MHC-I receptors on intestinal intraepithelial lymphocytes (iIELs) and show that T-cell receptor (TCR)-αβ CD8αα iIELs express multiple inhibitory receptors specific for MHC-I molecules, including CD94/NKG2A, Ly49A, and Ly49G2. However, the presence of MHC-I ligand for these receptors did not improve the response of iIELs to activation via the TCR. The absence of iIEL education by MHC-I receptors was not related to a lack of inhibitory function of these receptors in iIELs and a failure of these receptors to couple to the TCR. Thus, unlike NK cells, iIELs do not undergo an MHC-I-guided education process. These data suggest that education is an NK cell-specific function of inhibitory MHC-I receptors.

La prevención de la obesidad infantil desde la atención primaria

Boletín semanal para profesionales sanitarios de la Secretaría General de Salud Pública y Participación Social de la Consejería de Salud

La participación infantil en las políticas de salud

Boletín semanal para profesionales sanitarios de la Secretaría General de Salud Pública y Participación Social de la Consejería de Salud

El reconocimiento de la diferencia, la solidaridad y la igualdad de oportunidades, valores fundamentales en la atención infantil temprana

Boletín semanal para profesionales sanitarios de la Secretaría General de Salud Pública y Participación Social de la Consejería de Salud