Medications that target tumor necrosis factor alpha (TNFα), a protein involved in inflammation, have revolutionized the management of certain autoimmune diseases, but paradoxically, these agents might provoke the development of other autoimmune conditions.

In an Alimentary Pharmacology & Therapeutics study of 17,018 individuals with autoimmune diseases who were treated with anti-TNFα medications—mostly infliximab, etanercept, and adalimumab—and 63,308 individuals who were not, treatment with etanercept—but not other anti-TNFα agents—was linked with an elevated risk of developing inflammatory bowel disease: a two-fold increased risk of Crohn’s disease and a two-fold increased risk of ulcerative colitis.

“This study established that there is an increased risk of developing inflammatory bowel disease in individuals taking etanercept. Recognition of this phenomenon is important for clinicians taking care of these patients,” said lead author Joshua Korzenik, MD, of Brigham and Women’s Hospital, in Boston, MA. “Perhaps more importantly, this study suggests that inflammatory bowel disease may be one of the autoimmune diseases that can be provoked by anti-TNFα agents. This suggests that there may be a common mechanism of immune dysregulation underpinning these diseases.”