The study team identified five new gene regions that raise the risk of early-onset IBD, on chromosomes 16, 22, 10, 2 and 19. The most significant finding was at chromosome locus 16p11, which contains the IL27 gene that carries the code for a cytokine, or signaling protein, also called IL27. "This cytokine acts on a biological pathway, the T-helper 17 pathway, which plays a key role in causing intestinal inflammation," said Hakonarson. T helper 17 cells are recently discovered cells that lead to severe inflammation and tissue injury in autoimmune diseases. IBD is an autoimmune disease, in which a person's immune system runs out of control and attacks the body.
"There are many cytokines in our immune system, but our research strongly suggests that IL27 has a primary causative role in IBD," added Hakonarson. "This gene discovery makes sense in terms of our functional understanding of the disease."
Some current IBD drugs are monoclonal antibodies that act on another cytokine, called tumor necrosis factor, which contributes to inflammation. Although much research remains to be done, the current study may provide a basis for developing drugs that target the cytokine IL27's action, for patients with the disease-causing IL27 gene variant.
One strength of the current study, in addition to its large sample size, is the collaboration of many leading pediatric IBD research programs. In addition to The Children's Hospital of Philadelphia, other centers with principal investigators who played key roles were the Hospital for Sick Children of the University of Toronto; the University of Edinburgh, UK; Cedars Sinai Medical Center, Los Angeles; Emory University, Atlanta; and the IRCCS-CSS Hospital, S. Giovanni Rotondo, Italy.
|Contact: John Ascenzi|
Children's Hospital of Philadelphia