Helicobacterpylori-induced genotoxic damage in human b lymphocytes

ABSTRACT

Helicobacter pylori [H. pylori] is recognized as the causative agent of peptic and duodenal ulcers, gastric adenocarcinoma, and low-grade mucosa-associated lymphoid tissue [MALT] lymphoma. In the present study, we investigate the genotoxic damage of lysates of H, pylori in human B lymphocytes. Human B lymphocytes were treated with 0, 10, 20, and 30 microg/mL of total protein concentration of lysates obtained from H. pylori isolates from dyspeptic patients. Direct H. pylori-induced DNA damage was investigated by the in vitro cytokinesis-block micronucleus assay which detects chromosomal fragments and maldistributed whole chromosomes. The total mean micronuclei number [tMMN] observed per 1000 binucleus B cells significantly correlated with increasing protein concentration of H pylori lysates [r[2]=0.994, p=0.006]. The highest tMMN [3.81-fold] was observed in cells treated with 30 microg/mL of H, pylori lysate [12.43 +/- 1.91] when compared with the control [3.26 +/- 0.48]. This study provides evidence of the direct effect of H, pylori in chromosomal breakage of human B lymphocytes, which might lead to the development of abnormal B cells. Long-term infection by H. pylori has been implicated in epithelial cell damage as a result of continuous induction of the immune system by bacterial antigens. However, the results of this study propose that persistent H. pylori infection could also directly damage B lymphocyte DNA from which gastric MALT lymphoma arises