Researchers at Washington University School of Medicine have published two studies associating two different gut immune cell genes to inflammatory bowel disease (IBD) and Crohn's disease.
Previous studies revealed that some Crohn’s disease patients have a mutation in the gene Atg16L1. In the first report, researchers characterized mice that were hypomorphic for Atg16L1 protein expression, and validated conclusions by analyzing intestinal tissues from patients carrying the risk allele. Reduced Atg16L1 had pronounced effects on Paneth cells, immune cells in the lining of a portion of the small intestine. While the Paneth cells survive, their ability to secrete peptide granules to defend against infection is significantly impaired.
More research needs to be done to determine why having abnormal Paneth cells would predispose a person to Crohn's disease or to what degree other genes linked to Crohn's may affect the Paneth cell.
The second study identified a rare immune cell in the lymphoid tissues that could have a therapeutic role in IBD. The new cells are a type of natural killer (NK) cells, white blood cells typically known to eliminate tumors and virus-infected cells.
Some of the signals that activate the newly discovered cells are the same signals that turn on a different immune cell with strong inflammatory properties that can promote cell death and tissue damage if chronically active. But the anti-inflammatory cells, termed NK-22 cells, have the opposite effect — they promote cell proliferation and wound healing. The finding suggests that these cells play a role in maintaining a balance in the immune system between inflammatory processes and anti-inflammatory processes.
Researchers believe that if there are methods developed to culture NK-22 cells, they may be able to use them to promote healing and protect the gastrointestinal tract from a variety of inflammatory diseases.