Lack of association among TNF-α gene expression,-308 polymorphism (G > A) and virulence markers of Helicobacter pylori

Background: Tumor necrosis factor plays a critical role in the pathogenesis of gastric diseases such as gastric cancer, and an abnormal inflammatory response has frequently been observed in dyspeptic patients. Helicobacter pylori infection can induce a gastric mucosal inflammatory response that may be influenced by -308 (G > A) polymorphisms and gene expression of the TNF-alpha gene. Methods: One hundred and thirty-four gastric biopsy samples were collected from patients of both genders (61 male and 73 female, mean age 40.3 +/- 24.2 years) with gastric symptoms. The -308 (G > A) polymorphism of TNF-alpha was characterized using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The expression level was measured using real-time PCR, and relative quantification (RQ) was calculated using the comparative CT method (2(Delta Delta CT)). Results: The analysis revealed an increase in TNF-alpha gene expression in patients with gastritis; on the other hand, no statistical differences were observed in patients with gastric cancer. In addition, no association was found among -308 polymorphism genotypes, virulence markers, or TNF-alpha gene expression. Conclusions: Helicobacter pylori induces a large increase in TNF-alpha expression in patients with gastritis, regardless of tissue inflammation, but after the tissue becomes neoplastic, the presence of bacteria did not influence expression. These results suggest that the TNF-alpha pathway may play an important role in the progression from gastritis to gastric cancer