US researchers have developed a non-invasive method to identify bacteria that cause inflammation when they cross the gut barrier, potentially opening the door for new ways to treat diseases like obesity, liver disease, inflammatory bowel disease (IBD), cancer, and some neurological conditions.
Investigators from Cedars-Sinai Medical Centre and the National Institute of Allergy and Infectious Diseases in the US studied antibodies present in the body to identify which specific gut microbes may have activated the immune system in a particular disease. They published their findings in the peer-reviewed journal Science Translation Medicine in August.
“Microbes crossing the gut barrier frequently generate inflammation and activation of the immune system, which are fundamental hallmarks of many inflammatory disorders,” Vujkovic-Cvijin, assistant professor in the Department of Biomedical Sciences and Gastroenterology at Cedars-Sinai and one of the authors of the study, said in a statement.
“By understanding which specific microbes are crossing the gut and causing inflammation in a disease, we then can devise methods to get rid of those microbes to stop the disease,” he added.
To do this, the researchers utilised a high throughput sequencing technique to calculate the IgG score – a measure of the quantity of antibodies present against a gut microbe strain. Moreover, this allowed them to study previous immune responses of the body towards this inflammation and not just ongoing inflammation.
Antibodies are molecules produced by the immune system that combine with bacteria, viruses, and other foreign objects to neutralise them. IgG or ‘Immunoglobulin G’ is a type of antibody that accounts for more than 75% of all antibodies produced by our immune cells.
Understanding Inflammatory Bowel Disease
To validate this method, the researchers applied the technique to study individuals with IBD and found several bacteria such as Collinsella, Bifidobacterium, Lachnospiraceae and Ruminococcaceae were targeted by the immune system. This was not the case in healthy control subjects.
They built a database containing the information of different gut microbiota present in human guts and then used the sequencing technique to identify the bacteria species that caused increased IgG levels.
“Many of the bacteria we identified haven’t been thought of as potential causative drivers of this disease,” Vujkovic-Cvijin said. He added that the microbial activity may be relevant to IBD’s progression, possibly yielding a therapeutic target for the disease.
Suzanne Devkota, a co-author of the study said that the effects of bacteria migrating out of the gut into other tissues needed to be better understood, prompting the development of a non-invasive tool to do this.
The team plans to continue its study to understand the mechanism in which the identified gut bacteria cause inflammation and contribute to the progression of IBD.