The Adipokine Omentin in Late-stage Rheumatoid Arthritis and Endstage Osteoarthritis

To the Editor: In the past several years, adipokines have gained a lot of attention in the field of rheumatic diseases1. Rheumatoid arthritis (RA), for example, is associated with an altered production of adipokines1, and there is some evidence of involvement of adipokines in the pathophysiology of RA as suggested by in vitro 1 and in vivo data2,3. The term “adipokines” was originally used to describe cytokine-like factors secreted by adipose tissue, but it turned out that many adipokines are also produced at other sites including the joints1,4,5, where they might have an influence on effector cells of RA or osteoarthritis (OA) pathophysiology. As an adipokine, omentin was first found in omental adipose tissue from patients with Crohn disease6. Before this, it was identified as a secretory glycoprotein able to bind to galactofuranosyl residue on various microorganisms, suggesting a function in immune recognition of certain pathogens. It has also been described as a lactoferrin-binding protein with lactoferrin being a protein with multiple immunological functions. Omentin is highly abundant in human plasma6. It displayed antiinflammatory and antiatherogenic properties in obese patients7 … Address correspondence to Dr. K.W. Frommer, Department of Internal Medicine and Rheumatology, University of Giessen, Kerckhoff Clinic, Benekestrasse 2-8, D-61231 Bad Nauheim, Germany. E-mail: k.frommer{at}kerckhoff-klinik.de