[Epithelial cell in intestinal homeostasis and inflammatory bowel diseases]. / Rôle de la cellule épithéliale dans l'homéostasie intestinale et les maladies inflammatoires chroniques de l'intestin.

Crohn's disease (CD) and ulcerative colitis (UC) are the principal inflammatory bowel diseases (IBD) which physiopathology is currently poorly elucidated. During these diseases, the participation of the epithelial cell in the installation and the perpetuation of the intestinal inflammation is now clearly implicated. In fact, the intestinal epithelium located at the interface between the internal environment and the intestinal luminal, is key to the homeostatic regulation of the intestinal barrier. This barrier can schematically be regarded as being three barriers in one: a physical, chemical and immune barrier. The barrier function of epithelial cell can be altered by various mechanisms as occurs in IBD. The goal of this article is to review the literature on the role of the epithelial cell in intestinal homeostasis and its implication in the IBD.

Tolllike receptor 4 (TLR4) polymorphisms in Tunisian patients with Crohn's disease: genotype-phenotype correlation.

BACKGROUND: The immune responses to bacterial products through the pattern recognition receptor (PRR) play a pivotal role in pathogenesis of Crohn's disease. A recent study described an association between CD and some gene coding for bacterial receptor like NOD2/CARD15 gene and TLR4. In this study, we sought to determine whether TLR4 gene was associated with Crohn's disease (CD) among the Tunisian population and its correlation with clinical manifestation of the disease. METHODS: 90 patients with CD and 80 healthy individuals are genotyped for the Asp299Gly and Thr399Ile polymorphisms by restriction fragment length polymorphism analysis. RESULTS: The allele and genotype frequency of the TLR4 polymorphisms did not differ between patients and controls. The genotype-phenotype correlation permitted to show that the Thr399Ile polymorphism was associated with early onset disease. CONCLUSION: this study reported the absence of association between CD and TLR4 gene in the Tunisian population, but this gene could play a role in clinical expression of the disease.

Crohn's disease and polymorphism of heat shock protein gene HSP70-2 in the Tunisian population.

BACKGROUND AND AIMS: Crohn's disease is a multifactorial disorder with a pivotal role of the genetic component. HSP70-2 gene, located in IBD3 region, has a PstI polymorphic site associated recently with Crohn's disease especially with a perforating form. In this study, we sought to determine whether this polymorphism was associated with Crohn's disease in the Tunisian population and its correlation with clinical manifestation of the disease. METHODS: In all, 148 patients with Crohn's disease and 81 healthy individuals were genotyped for the HSP70-2 PstI polymorphism by restriction fragment length polymorphism analysis. RESULTS: The allele and genotype frequency of the PstI polymorphism did not differ between patients and controls. Furthermore, this polymorphism was not associated with specific disease behavior. CONCLUSION: This study reported the absence of association between Crohn's disease and HSP70-2 gene in the Tunisian population. The allele A of PstI polymorphism was not associated with phenotype of the disease.

[The pathophysiology of irritable bowel syndrome]. / Physiopathologie du syndrome de l'intestin irritable.

The irritable bowel syndrome (IBS) is a frequent gastrointestinal disorder (10 -15% of the population). It is characterized by chronic abdominal pain with modification in the bowel habits. The diagnosis is based of ROME II criteria. The pathophysiology of the SII remains unknown . It result from visceral hypersensitivity with anomalies of the digestive motility. These anomalies are secondary of dysfunction of the brain - gut axis modulated by environmental and the psychosocial factors. The understanding of the pathophysiological mechanisms of the SII and in particular the function of the brain-gut axis will permit a better handling of the patients. Indeed, the present knowledge of the neurotransmitter implied in the communication between the central nervous system and the digestive tract are currently the basis of the new therapies aimed to modulate the mechanisms implicated in the causation of the several symptoms of IBS. These novel pharmacotherapy should reduce the indirect societal and costs of IBS.

CARD15/NOD2 in a Tunisian population with Crohn's disease.

Crohn's disease (CD) is a heterogeneous disorder. A genetic linkage to chromosome 16 (IBD1) has been previously observed and replicated in unrelated populations. Recently, in this region, NOD2/CARD15 has been identified as a susceptibility gene. The aim of this report is to determine whether this gene is implicated in CD in a Tunisian population. One hundred thirty patients with CD and 90 healthy individuals were genotyped for the three common NOD2 variants (C2104T in exon 4, G2722C in exon 8, and 3020insC in exon 11). Furthermore, the 11 exons of the NOD2 gene were sequenced in 20 patients with CD. Results showed that the frequency of the CARD15 variants in the Tunisian population is significantly lower than that observed in the European and American population. Direct sequencing of CARD15 did not permit us to identify a characteristic mutation in our population. No association was confirmed between CD and the NOD2 gene in our Tunisian population. Furthermore, the NOD2/CARD15 gene has a variable association with CD in different populations. These results indicate the genetic variation of CD in different ethnic groups.

[Genetics of inflammatory bowel disease]. / Genetique des maladies inflammatoires cryptogenetiques de l'intestin.

The Inflammatory Bowel Disease (IBD) are multifactorial diseases involving the interaction of genetic and environmental factors. In genetic terms, the IBD are polygenic and multigenic disorders with incomplete penetrance. In the late decade, investigators have applied the complementary techniques of genome-wide scanning and candidate gene analysis to search susceptibility genes. The IBD susceptibility regions, widely replicated, are in chromosomes 16 (IBD1), 12 (IBD2) and 6 (IBD3). Recently, a significant association have been reported with Crohn's disease and NOD2/ CARD15 gene. This gene is an appropriate candidate gene because its localization and function. More studies is necessary to confirm this association, search an other variants of this gene and other candidate gene. This studies provide best comprehension of the disease pathogenesis and deliver clinical application.