For some time, specialists who study arthritis have been interested in a substance called interleukin-6 (IL-6). IL-6 is a chemical that produces inflammatory effects in the body, and levels of IL-6 are elevated in people who have rheumatoid arthritis (RA). In a piece published in the journal Rheumatology, two rheumatologists presented the results of a systematic review of articles published on pain and mood in RA since 2005. They wanted to learn more about what effect IL-6 might have on pain, mood, and fatigue in people with RA.
The evidence, the authors concluded, supports the theory that IL-6 plays a key role in the development of RA-related fatigue. It also appears that a relationship exists between IL-6 and mood disorders — for one, the research showed that IL-6 is one of the most consistently elevated chemicals in RA patients with major depressive disorder. In addition, IL-6 plays a major role in stimulating what’s known as the hypothalamic-pituitary-adrenal (HPA) axis, which is the body’s central stress-response system, and patients with RA have impaired activity of the HPA axis. Finally, drugs that inhibit IL-6 (for example, tocilizumab [brand name Actemra], sarilumab [Kevzara], and sirukumab [Plivensia]) can play an important role in treating RA.
The importance of this new review lies in its conclusion that IL-6 not only plays a role in the way in which RA develops, but that it also contributes to what the authors referred to as the “secondary characteristics” of RA — pain, mood, and fatigue. As a result, they wrote, physicians who prescribe IL-6 inhibitors for their patients might want to advise them that the medications can not only help with pain, but with other problems as well.