Proinflammatory Effects of Calprotectin in Graves' Orbitopathy.

: Early detection and control of inflammation are important to manage Graves' orbitopathy (GO). We investigated the effects of calprotectin (S100A8/A9) on orbital fibroblast inflammation and GO pathogenesis.: We measured serum calprotectin, and mRNA expression in orbital fat/connective tissue from GO patients and healthy controls, and proinflammatory cytokines in primary cultured orbital fibroblasts.: The serum levels of S100A8/A9 and the expression of mRNA in orbital tissue were higher in the GO patients than in the healthy controls. The serum calprotectin levels positively correlated with the clinical activity score and serum thyroid-stimulating immunoglobulin levels. In cultured GO orbital fibroblasts, S100A8/A9 increased the expression of interleukin (IL)-6, IL-8, and monocyte chemotactic protein-1, as well as the phosphorylation of extracellular signal-regulated kinase and nuclear factor-κB.: We demonstrated the potential of calprotectin as a biomarker of GO severity and proinflammatory responses to S100A8/A9 in GO orbital fibroblasts.