Immunohistochemical staining of H. pylori from a gastric biopsy.Image credit: KGH, Wikimedia CommonsThe results were published Friday in the journal PLOS ONE in an article titled, “Human Immune Response to H. pylori HLA Class II Epitopes Identified by Immunoinformatic Methods.” This is the first time that human immune responses to the H. pylori pathogen have been described in such detail, and the researchers believe that a vaccine against the pathogen is within reach.

Helicobacter pylori, or H. pylori, is a bacterium that infects the stomach of half of the human population, leading to chronic gastric inflammation in all of those infected while also causing other adverse health effects. It is the most common cause of peptic ulcers, and its persistence in the stomach also gradually promotes gastric cancer development.

Recently, H. pylori infection has also been found to have some beneficial effects. It has been linked to protection against unrestrained inflammation in conditions such as asthma, inflammatory bowel disease, esophageal reflux and esophageal adenocarcinoma.

"The dual personality of H. pylori is a novel, unexpected finding," said URI Assistant Research Professor Lenny Moise. Moise is one of the leaders on the project, working alongside URI Research Professor Annie De Groot and Brown Alpert Medical School Professor Steven Moss.

To investigate how H. pylori stimulates both harmful and beneficial human immune responses, the research team used the recent availability of multiple H. pylori genome sequences coupled with advances in computerized algorithms (provided to the researchers by local biotech company EpiVax, Inc.) to identify 90 H. pylori-derived peptide sequences considered as potential immune epitopes. Testing them against human immune cells, the researchers found that these sequences elicited significantly higher inflammatory and immunosuppressive responses in those patients already infected by H. pylori.

"These experiments demonstrate the utility of immunoinformatics to identify vaccine and immunotherapeutic candidates," said De Groot, director of the Institute for Immunology and Informatics located on the URI Providence campus.

The research program is funded by a $13 million National Institutes of Health award entitled “Translational Immunology Research and Accelerated [Vaccine] Development,” also known as the TRIAD program headed by De Groot.

H. pylori infection is unevenly distributed, being most prevalent in resource-poor countries (between 70-90 percent) and in as few as 10 percent or less of some Western populations. Stomach cancer, which is largely attributable to H. pylori, is responsible for 10,900 deaths per year in the United States and about 738,000 deaths annually worldwide.