Original Article
Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 14, 2014; 20(42): 15715-15726
Published online Nov 14, 2014. doi: 10.3748/wjg.v20.i42.15715
Esophageal Helicobacter pylori colonization aggravates esophageal injury caused by reflux
Yun-Xiang Chu, Wei-Hong Wang, Yun Dai, Gui-Gen Teng, Shu-Jun Wang
Yun-Xiang Chu, Wei-Hong Wang, Yun Dai, Gui-Gen Teng, Shu-Jun Wang, Department of Gastroenterology, Peking University First Hospital, Beijing 100034, China
Author contributions: Chu YX and Wang WH contributed equally to this work; Chu YX performed the majority of experiments and wrote the manuscript; Wang WH designed the study and was involved in writing of the manuscript; Dai Y, Teng GG, and Wang SJ provided technical assistance; all of the authors read and approved the final version of the manuscript.
Supported by Grants from the National Natural Science Foundation of China, No. 81172271; and the Specialized Research Fund for the Doctoral Program of Higher Education, No. 20110001110064
Correspondence to: Wei-Hong Wang, Professor, Department of Gastroenterology, Peking University First Hospital, 8 Xishiku Avenue, Xicheng District, Beijing 100034, China. wangweihong@medmail.com.cn
Telephone: +86-10-83572616 Fax: +86-10-66518105
Received: January 30, 2014
Revised: April 22, 2014
Accepted: May 12, 2014
Published online: November 14, 2014
Abstract

AIM: To investigate esophageal Helicobacter pylori (H. pylori) colonization on esophageal injury caused by reflux and the related mechanisms.

METHODS: An esophagitis model, with acid and bile reflux, was surgically produced in male rats. The rats were randomly divided into either: (1) an esophagogastroduodenal anastomosis (EGDA) group; (2) an EGDA with H. pylori infection group; (3) a pseudo-operation with H. pylori infection group; or (4) a pseudo-operation group. All rats were kept for 36 wk. Based on the location of H. pylori colonization, the EGDA rats with H. pylori infection were subdivided into those with concomitant esophageal H. pylori colonization or those with only gastric H. pylori colonization. The esophageal injuries were evaluated grossly and microscopically. The expressions of CDX2 and MUC2 were determined by real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. Ki-67 antigen expression was determined by immunohistochemistry. The mRNA levels of cyclin D1, c-Myc, Bax and Bcl-2 were determined by RT-PCR. Cell apoptosis was evaluated using the TdT-mediated dUTP nick-end labeling method.

RESULTS: Esophagitis, Barrett’s esophagus (BE), and esophageal adenocarcinoma (EAC) developed in rats that underwent EGDA. When comparing rats with EGDA and concomitant esophageal H. pylori colonization to EGDA-only rats, the severity of injury (87.9 ± 5.2 vs 77.2 ± 8.6, macroscopically, 92.5 ± 8.0 vs 83.8 ± 5.5, microscopically, both P < 0.05) and the incidences of BE (80.0% vs 33.3%, P = 0.055) and EAC (60.0% vs 11.1%, P < 0.05) were increased. These increases were associated with upregulation of CDX2 and MUC2 mRNA (10.1 ± 5.4 vs 3.0 ± 2.9, 8.4 ± 4.6 vs 2.0 ± 3.2, respectively, Ps < 0.01) and protein (8.1 ± 2.3 vs 3.3 ± 3.1, 7.3 ± 4.0 vs 1.8 ± 2.7, respectively, all P < 0.05). The expression of Ki-67 (8.9 ± 0.7 vs 6.0 ± 1.7, P < 0.01) and the presence of apoptotic cells (8.3 ± 1.1 vs 5.3 ± 1.7, P < 0.01) were also increased significantly in rats with EGDA and concomitant esophageal H. pylori colonization compared with rats with EGDA only. The mRNA levels of cyclin D1 (5.8 ± 1.9 vs 3.4 ± 1.3, P < 0.01), c-Myc (6.4 ± 1.7 vs 3.7 ± 1.2, P < 0.01), and Bax (8.6 ± 1.6 vs 5.1 ± 1.3, P < 0.01) were significantly increased, whereas the mRNA level of Bcl-2 (0.6 ± 0.3 vs 0.8 ± 0.3, P < 0.01) was significantly reduced in rats with EGDA and concomitant esophageal H. pylori colonization compared with rats with EGDA only.

CONCLUSION: Esophageal H. pylori colonization increases esophagitis severity, and facilitates the development of BE and EAC with the augmentation of cell proliferation and apoptosis in esophageal mucosa.

Keywords: Helicobacter pylori, Esophagus, Metaplasia, Adenocarcinoma, Animal model

Core tip: The relationship between gastroesophageal reflux disease and Helicobacter pylori (H. pylori) is controversial. This study demonstrates that esophageal H. pylori colonization can aggravate esophageal injury and promote the incidence of Barrett’s esophagus and esophageal adenocarcinoma. Gastric H. pylori colonization did not aggravate esophageal mucosal lesions in rats with mixed reflux. However, esophageal H. pylori infection was associated with increased cell proliferation and apoptosis in the esophagi of rats with mixed reflux. Loss of balance between cell proliferation and apoptosis may be important in H. pylori-induced esophageal malignancy.