Relationship Between CagA,CagE Genes Of Helicobacter Pylori And Secretion Of IL-8 In Different Clinical Gastric Diseases

Background: Helicobacter pylori (HP) infection is almost always associated with gastric mucosa inflammation.but more advanced diseases such as peptic ulcers and gastric cancer occur only in part of infected patients. Although the pathogenesis of HP infection is not understood,several factors have been proposed as possible virulent determinants. Traditionally CagA is considered as virulent determinant and the production of CagA protein is reported the marker of virulence. CagA positive strain induce interleukin-8 (IL-8) secretion from gastric epithelial cells. However, recent studies have indicated that it is other genes in Cag Pathogenicity Island (CagPAI) that are responsible for IL-8 induction. CagE gene is located in CagPAI downstream. CagE may closely associate with IL-8 secretion.Aim: To detect the association between CagA and CagE genes. To explore the pathogenic mechanism of HP. To investigate distribution of HP virulent strain in different gastric diseases.Methods: Under endoscopy we obtain 105 patients' gastric biopsy specimens which were used to detect presence of HP by bacteria culture,UreA-PCR and 14C-Urease Breathing Test . We test CagA gene and CagE gene with PCR method from those HP positive specimens. We further detect the level of IL-8 in local gastric mucosa with ELISA.Results: Total HP positive specimens are 88 cases. (1).67 cases were infected with strains possessing CagA gene and 62 cases with CagE gene. The positive rate of CagA gene was significantly higher in CAG 85.7%(13/21), GU 82.1%(23/28)and GC 86.7% (13/15) than in CSG54.1%( 13/24) (P<0.05). (2). CagA gene has close relationship with CagE gene (P<0.01). (3). The level of IL-8 in local gastric mucosa from patients with CagA gene is higher in CAG, GU and GC than in CSG (P<0.05). Patients with CagA and CagE gene positive have more IL-8 secretion than those with negative genes (p<0.05).Conclutions: CagA is a virulent factor concerning with advanced diseases. CagA gene closely related with CagE gene and they both promote secretion of IL-8 in local gastric mucosa which will play key role in advanced gastric diseases.