Role of SerpinA3 in the Pathogenesis of Graves' Orbitopathy in Orbital Fibroblasts.

Purpose: We investigated the implications of SerpinA3, a secretory serine protease inhibitor, in inflammation and adipogenesis of Graves' orbitopathy (GO). To identify its precise function in GO pathogenesis, we evaluated the role of SerpinA3 in the inflammation and adipogenesis of GO.

Methods: SerpinA3 expression was compared between GO (n = 30) and normal participants (n = 28) in orbital tissue explants using real-time PCR. Orbital fibroblasts from GO (n = 3) and normal participants (n = 3) were transfected with or without small interfering RNA against SerpinA3 before IL-1β stimulation. Western blotting assessed inflammatory cytokine and signaling molecule expression. Adipogenic differentiation was assessed using Oil Red O staining, and adipogenic marker expression was determined through Western blotting. Enzyme-linked immunosorbent assay was used to compare prostaglandin E2 (PGE2) and hyaluronan levels in GO (n = 4) and normal participants (n = 3).

Results: SerpinA3 transcript levels were significantly higher in GO orbital tissues. Silencing SerpinA3 suppressed the IL-1β-induced expression of IL-6, IL-8, monocyte chemotactic protein 1, intercellular adhesion molecule 1, cyclooxygenase 2, and PGE2 and attenuated the levels of phosphorylated nuclear factor κB, Akt, extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. Moreover, silencing SerpinA3 reduced hyaluronan production, adipogenic differentiation, and adipogenic marker expression, including peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding proteins α and β, adipocyte protein 2, adiponectin, and leptin.

Conclusions: Silencing SerpinA3 attenuated the expression of proinflammatory mediators, adipogenic differentiation, and hyaluronan production. Our results indicate that SerpinA3 plays a significant role in GO and may serve as a novel therapeutic target.