Expression and function of ghrelin in rheumatoid arthritis

Activation of the immune system in rheumatoid arthritis (RA) is accompanied by perturbations in energy homeostasis. Pro-inflammatory cytokines lead to metabolic changes which results in increased mortality among RA patients. Ghrelin is a gastric hormone that is secreted in response to nutrient starvation and it is a major regulator of blood glucose levels. Increased production of ghrelin has been linked to anti-inflammatory effects in models of chronic inflammation. In this study we investigated the expression of ghrelin, its receptor GHR-S and activating enzyme GOAT in synovial material in RA under inflammatory and standard conditions. Furthermore effects of ghrelin on production of pro-inflammatory cytokines in synovial fibroblasts from RA are shown. Ghrelin, GHR-S and GOAT were expressed in RA and osteoarthritis (OA) synovial tissue. Incubation of RA and OA synovial fibroblasts with TNF significantly increased GHRS-S and ghrelin protein levels, whereas cortisol in high concentrations (