title: Differences in gastric mucosal microbiota profiling in patients with chronic gastritis, intestinal metaplasia, and gastric cancer using pyrosequencing methods.
abstract: BACKGROUND
  Helicobacter pylori (H. pylori) infection plays an important role in the early stage of cancer development. However, various bacteria that promote the synthesis of reactive oxygen and nitrogen species may be involved in the later stages. We aimed to determine the microbial composition of gastric mucosa from the patients with chronic gastritis, intestinal metaplasia, and gastric cancer using 454 GS FLX Titanium.
  
  
  METHODS
  Gastric mucosal biopsy samples were collected from 31 patients during endoscopy. After the extraction of genomic DNA, variable region V5 of the 16S rRNA gene was amplified. PCR products were sequenced using 454 high-throughput sequencer. The composition, diversity, and richness of microbial communities were compared between three groups.
  
  
  RESULTS
  The composition of H. pylori-containing Epsilonproteobacteria class appeared to be the most prevalent, but the relative increase in the Bacilli class in the gastric cancer group was noticed, resulting in a significant difference compared with the chronic gastritis group. By analyzing the Helicobacter-dominant group at a family level, the relative abundance of Helicobacteraceae family was significantly lower in the gastric cancer group compared with chronic gastritis and intestinal metaplasia groups, while the relative abundance of Streptococcaceae family significantly increased. In a UPGMA clustering of Helicobacter-dominant group based on UniFrac distance, the chronic gastritis group and gastric cancer group were clearly separated, while the intestinal metaplasia group was distributed in between the two groups. The evenness and diversity of gastric microbiota in the gastric cancer group was increased compared with other groups.
  
  
  CONCLUSIONS
  In Helicobacter predominant patients, the microbial compositions of gastric mucosa from gastric cancer patients are significantly different to chronic gastritis and intestinal metaplasia patients. These alterations of gastric microbial composition may play an important, as-yet-undetermined role in gastric carcinogenesis of Helicobacter predominant patients.
authors: Department of Internal Medicine, Hanyang University Guri Hospital, Gyeonggi-Do, Korea.
authors: Chang Soo
authors: CS
authors: Eun
authors: Byung Kwon
authors: BK
authors: Kim
authors: Dong Soo
authors: DS
authors: Han
authors: Seon Young
authors: SY
authors: Kim
authors: Kyung Mo
authors: KM
authors: Kim
authors: Bo Youl
authors: BY
authors: Choi
authors: Kyu Sang
authors: KS
authors: Song
authors: Yong Sung
authors: YS
authors: Kim
authors: Jihyun F
authors: JF
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D015373:Bacterial Typing Techniques; D044822:Biodiversity; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology*; D005756:Gastritis / Q000382:microbiology*; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007410:Intestinal Diseases / Q000382:microbiology* / Q000473:pathology; D008297:Male; D008679:Metaplasia / Q000382:microbiology; D064307:Microbiota; D008875:Middle Aged; D011446:Prospective Studies; D013274:Stomach Neoplasms / Q000382:microbiology
keywords: 16S ribosomal RNA; H. pylori; carcinogenesis; gastric cancer