Prevalence and virulence factors of Helicobacter pylori isolated from oral cavity of non-disease, gastritis, and gastric cancer patients

Abstract

Background/purpose: The oral cavity is considered a reservoir of Helicobacter pylori associated with gastric infection. It aimed to examine the prevalence of H. pylori strains from the oral cavity and gastric tissue of patients with different stage of gastric-diseases. Strains were further characterized for virulence genes, adhesion ability, and inflammation responses.

Materials and methods: 11 non-disease, 15 gastritis, and 15 gastric cancer participated in the study. After clinical examination, gastric biopsies, saliva and plaque samples were collected and H. pylori levels were examined by real-time PCR and cultivation. The cagA and vacA genes were investigated from the culture strains. Adhesion ability and pro-inflammatory responses were analyzed in comparison between the presence of virulent genes and disease status.

Results: Relatively poor periodontal condition was found among gastric cancer patients. Prevalence of H. pylori-positive was 84.8% and 19.5% by real-time PCR and cultivation, respectively. The cagA and vacA gene-positive strains were 52.6% and 5.3%, respectively, which were found more in gastric cancer patients. The cagA gene-positive strains were found to be higher in gastric cancer patients, and strains had significantly higher adhesion ability and pro-inflammation expressions than the cagA gene-negative strains.

Conclusion: Colonization by H. pylori in oral cavity was confirmed, and the cagA gene-positive strains play a crucial role in both adhesion and inflammatory responses. The presence of H. pylori and its virulence gene in oral cavity should be received attention. An eradication of such strains from oral cavity may help to prevent the transmission and recolonization to gastric organs.

Keywords: Adhesion ability; Gastric cancer; Helicobacter pylori; Periodontal diseases; Pro-inflammatory responses; cagA gene.

Figure 1

The expression of the cagA gene-positive and cagA gene-positive strains among the strains derived from non-cancer and cancer patients were shown as a boxplot (exhibiting five values from the bottom to the top: the minimum values, the first quartile, the median is marked by a horizontal line in the box, the third quartile, and the maximum values, respectively). Lowercase letters showed significant difference of mRNA expression in the same disease status. Capital letters showed significant difference of mRNA expression in the same cagA positive or cagA negative strains in different disease status (P < 0.05).

Figure 2

Adhesion abilities of all clinical H. pylori strains to various cell lines (A), and compared between cagA gene-positive and cagA gene-positive strains (B). Results showed as a boxplot (exhibiting five values from the bottom to the top: the minimum values, the first quartile, the median is marked by a horizontal line in the box, the third quartile, and the maximum values, respectively). Lowercase letters showed significant difference of adhesion ability between the different tested cell lines and in difference between the cagA positive or cagA negative strains in the same cell line (P < 0.05).

Figure 3

Adhesion abilities H. pylori strains to AGS and H357 cell lines showed as a boxplot (exhibiting five values from the bottom to the top: the minimum values, the first quartile, the median is marked by a horizontal line in the box, the third quartile, and the maximum values, respectively). Lowercase letters showed significant difference between the cagA positive and cagA negative strains in the same disease status. Capital letters showed significant difference in the same cagA positive or cagA negative strains in different disease status (P < 0.05).

Figure 4

Pro-inflammation expressions (IL-1β, IL-6, IL-8, and TNF-α) and presence of cagA gene in periodontal fibroblast PDL (A) and AGS (B) cells, showed as a boxplot (exhibiting five values from the bottom to the top: the minimum values, the first quartile, the median is marked by a horizontal line in the box, the third quartile, and the maximum values, respectively). Lowercase letters showed significant difference between the cagA positive and cagA negative strains in the same disease status. Capital letters showed significant difference in the same cagA positive or cagA negative strains in different disease status (P < 0.05).