Relative Overexpression of Macrophage-Derived Cytokines in Orbital Adipose Tissue from Patients with Graves’ Ophthalmopathy

Abstract

Graves’ ophthalmopathy (GO) is an autoimmune disorder involving the adipose and connective tissues of the orbit. The study of cytokines present in these tissues may reveal the nature of the cells and immune responses involved in GO pathogenesis. In the current study, we performed relative quantification of the expression of cytokine genes in orbital adipose tissue from patients with GO (n = 6) and normal individuals (n = 2). Real-time RT-PCR was performed using fluorescent probes and primers for cytokines including IL-1β, IL-2, IL-4, IL-5, IL-8, IL-10, IFN-γ, and TNF-α. Results showed IL-1β to be the gene having the greatest fold expression increase over normal in four of six patients. TNF-α was increased in all six GO patients. In addition, IL-8, IL-10, and IFN-γ were increased in five of six GO patients. We found no evidence of either IL-4 or IL-5 expression in any of the GO or normal samples. The increased expression of the macrophage-derived cytokines IL-1β, TNF-α, and IL-10 suggests the presence of macrophage activation and ongoing antigen presentation within the orbit in GO. In addition, the overexpression of IFN-γ, without evidence of IL-4 or IL-5 expression, supports the concept that cell-mediated, rather than humoral, immunity plays the predominant role in pathogenesis of this disorder.