Association of peptic ulcer with increased expression of Lewis antigens, but not vacuolating cytotoxin activity or babA2 gene status, in Helicobacter pylori strains from China

Abstract

Controversies exist regarding the virulence factors, such as vacA, babA2 and Lewis blood group antigens, of Western and Asian strains of Helicobacter pylori. The aim of the present study was to determine the significance of these potential virulence factors in the Chinese population. Seventy-two strains of H. pylori isolated from patients in Zhengzhou, China, including 43 cases of peptic ulcer (PU) and 29 cases of chronic gastritis, were determined. Vacuolating cytotoxin assay was performed by HeLa cells. The expression of Le blood group antigens (Le(a), Le(b), Le(x) and Le(y)) was performed by enzyme-linked immunosorbent assay (ELISA). babA2 gene was identified by polymerase chain reaction. Frequencies were compared using two-tailed Fisher's exact test. Cytotoxin activities were compared using Spearman's rank correction test. Vacuolating cytotoxin activity was detected in 61 of the 72 strains (84.7%), but there was no significant difference in vacuolating cytotoxin activity (83.7% vs 86.2%, P = 0.821) or titer (4.4 +/- 3.8 vs 4.2 +/- 4.1, P = 0.876) between the PU and gastritis strains. Significantly more PU strains expressed two or more Lewis antigens (Le(x), Le(y), Le(a) or Le(b)) than strains from the chronic gastritis patients (90.7% vs 65.5%, P = 0.029). Of the 43 strains from PU patients, 17 (39.5%) were positive for babA2, compared with 11 (38.5%) of the 29 strains from gastritis patients (P = 0.924). There was no significant difference in the vacuolating cytotoxin activity or titer between strains expressing two or more Lewis antigens and less than two antigens (84.5% vs 85.7%, P = 1.000; 4.4 +/- 4.2 vs 4.3 +/- 3.2, P = 0.965). Of the 72 H. pylori strains, 28 were babA2 positive, of which 24 were cytotoxic, compared with 37 of 44 babA2-negative strains (P = 1.000). The present study suggests that PU is associated with increased Lewis antigen expression, but not vacuolating cytotoxin production or the presence of babA2, in the H. pylori strains in the Chinese population.