Superoxide dismutase activity of Helicobacter pylori per se from 158 clinical isolates and the characteristics

Abstract

We investigated the correlation between the SOD activity of Helicobacter pylori (H. pylori) and gastroduodenal diseases and the characteristics of strains exposed to oxidative stress. Two sequenced strains, 26695 and J99, and clinical isolates from 156 Japanese patients with gastroduodenal diseases such as gastric cancer (n = 59) and non-cancer (n = 97) were used. SOD activities of all 158 isolates were measured and were divided into three groups: high-SOD activity (>0.22, n = 2), moderate-SOD activity (0.15 0.22, n = 16) and low-SOD activity (<0.15, n = 140). Expressions of H. pylori Fe-SOD were examined by western blotting with anti-H. pylori Fe-SOD antibody prepared inhouse, and the profiles of Fe-SOD activity were investigated by zymogram with activity staining in native-PAGE. The characteristics of strains from high-SOD and low-SOD groups were examined under oxidative stress by paraquat. The average of H. pylori SOD activity was significantly higher in the cancer group than in the non-cancer group (P < 0.05). However, irrespective of SOD activity level, the amount of Fe-SOD expressed was variable among individual strains. Zymogram revealed a single band in moderate-SOD and low-SOD strains, but multiple bands in high-SOD strains were observed. These bands were confirmed as H. pylori Fe-SOD. Under oxidative stress with paraquat, low-SOD strains were drastically eliminated without inducible SOD activity; however, high-SOD strains were still viable with increased SOD activity. This study is the first to exhibit the characteristics of high-SOD activity strains representing multiple bands in zymograms and the correlation between H. pylori SOD activity and gastric cancer. Key words

Helicobacter pylori Virulence Factors—Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

“…Except for colonization, SOD expression is crucial for bacterial growth and survival primarily in the host microenvironment with a high intensity of oxidative stress [128]. Furthermore, there is a relationship between SOD activity and the onset and progress of gastric diseases [129].…”

Polyamine- and NADPH-dependent generation of ROS during Helicobacter pylori infection: A blessing in disguise

“…Moreover, it has been reported that the enzyme SodB is essential for H. pylori to colonize mice [77], demonstrating that O 2 •− and/or H 2 O 2 are effectively released in vivo and target the bacteria in the gastric mucosa. It has been also shown that the H. pylori strains that are associated with gastric cancer exhibit more SOD activity than those carried by patients with gastritis or gastric and duodenal ulcers, further evidencing that SodB has a major function in the virulence of H. pylori [79]. …”

Pathogenesis of Helicobacter pylori Infection

“…ROS can damage major cellular constituents if the host is unable to quench the free radical overproduction . Both the bacterium and gastric cells respond to oxidative stress by altering the activity of their antioxidant systems. A study showed that H. pylori can interfere with the antioxidant response of the host.…”