Characterization of cytotoxic Citrobacter braakii isolated from human stomach

作者：Meng-Chao Yu, Fangyu Xie, Chengzhen Xu, Ting Yu, Yixuan Wang, Shuzhen Liang, Quanjiang Dong, Lili Wang · 发表于：FEBS Open Bio · 年份：2024 · DOI：10.1002/2211-5463.13770 · 被引用次数：5 · 研究领域：Helicobacter pylori-related gastroenterology studies、Probiotics and Fermented Foods、Infections and bacterial resistance

Citrobacter braakii (C. braakii) is an anaerobic, gram-negative bacterium that has been isolated from the environment, food, and humans. Infection by C. braakii has been associated with acute mucosal inflammation in the intestine, respiratory tract, and urinary tract. However, the pathogenesis of C. braakii in the gastric mucosa has not yet been clarified. In this study, the bacterium was detected in 35.5% (61/172) of patients with chronic gastritis (CG) and was closely associated with the severity of mucosal inflammation. Citrobacter braakii P1 isolated from a patient with CG exhibited urease activity and acid resistance. It contained multiple secretion systems, including a complete type I secretion system (T1SS), T5aSS and T6SS. We then predicted the potential pilus-related adhesins. Citrobacter braakii P1 diffusely adhered to AGS cells and significantly increased lactate dehydrogenase (LDH) release; the adhesion rate and LDH release were much lower in HEp-2 cells. Strain P1 also induced markedly increased mRNA and protein expression of IL-8 and TNF-α in AGS cells, and the fold increase was much higher than that in HEp-2 cells. Our results demonstrate proinflammatory and cytotoxic role of C. braakii in gastric epithelial cells, indicating the bacterium is potentially involved in inducing gastric mucosa inflammation.