Crohn's disease is a type of inflammatory bowel disease (IBD), and the causes are unclear but studies have linked it to autoimmunity, genetic risk factors, stress, and certain environmental conditions. Scientists have now found an association between Crohn's and Epstein-Barr virus (EBV). While EBV is a direct cause of mononucleosis, recent research has suggested that it may be related to the development of multiple sclerosis, lupus, and rheumatoid arthritis, which are also autoimmune disorders. Studies have shown that there are abnormally high levels of EBV in Crohn's disease patients.
Now reporting in Gastroenterology, researchers have determined that EBV can increase the risk of Crohn's disease. In this work, the investigators assessed military service record data and found that people who had been infected with EBV (because they carried anti-EBV antibodies) were three times more likely to have Crohn's. EBV exposure generally preceded an individual's Crohn's diagnosis by about six years.
"We went into this study not looking for EBV; we were looking for any virus that might elicit inflammatory bowel disease," noted senior study author Scott Snapper, MD, Ph.D., director of the Inflammatory Bowel Disease Center at Boston Children's Hospital. "Then, when EBV was a hit, we looked very specifically at immune responses to EBV with more detailed tests."
The scientists also looked for EBV infection in another group of 5,000 children who were relatives of Crohn's patients; this group had an average age of 11 years. However, EBV did not predict Crohn's in this case. The study authors suggested that because many of these individuals may already carry Crohn's risk factors, the results were unclear. The immune system of children may also react differently to EBV than that of adults.
"Responding to certain organisms early in life may boost the immune system in a way that prevents immune-mediated disease," Snapper suggested.
The researchers want to investigate the EBV-Crohn's link further to determine how the virus may be driving disease.
"Mechanistically, we need to understand exactly how EBV alters the immune system, leading to Crohn's disease," Snapper said. "If you could figure out the mechanisms, you could come up with new therapies."
Sources: Children's Hospital Boston, Gastroenterology