Chitosan Inhibits Inflammation And Adipogenesis Of Orbital Fibroblasts From Graves Ophthalmopathy

Purpose The aim of this study was to investigate the roles of chitosan on inflammation and adipogenesis of primary cultured orbital fibroblasts from Graves Ophthalmopathy(GO).Methods To investigate the effect of chitosan on cell viability of orbital fibroblasts,cell viability,apoptosis and cell cycle were determined by the Cell Counting Kit-8(CCK-8),the Annexin V-FITC/PI kit,and flow cytometry,respectively.Inflammation of orbital fibroblasts was stimulated by IL-1?.The levels of interleukin-6(IL-6)and prostaglandin E-2(PGE-2)were measured using an enzyme-linked immunosorbent assay(ELISA).The expression of cyclooxygenase-2(COX-2)was measured by real-time PCR and Western blot assay.Phosphorylation of c-Jun N-terminal kinase(JNK)was evaluated by Western blot assay.An inhibitor of JNK was used to investigate the signal transduction pathway of cytokine production.Orbital fibroblasts were co-cultured with chitosan in the adipose differentiation medium.The production of adipose cells was stained by Oil Red O.the protein levels of FABP4,adiponectin,C/EBP? and PPAR-? were evaluated by Western blot assay.The phosphorylation of AKT was also evaluated by Western blot assay.Results: The results showed that IL-1? significantly increased the expression of IL-6,PGE-2,and COX-2 in orbital fibroblasts.Phosphorylation of JNK was promoted by IL-1?.IL-6 and PGE-2 were modulated by the JNK signaling pathway as determined with inhibition experiments.Chitosan downregulated expression of IL-1?–stimulated IL-6,COX-2 and PGE-2 and downregulated phosphorylation of JNK.Orbital fibroblasts differentiated to adipose cells in differentiation medium.Chitosan inhibited the production of adipose cells dyed by Oil Red O.Chitosan significantly decreased the protein levels of FABP4,adiponectin,C/EBP? and PPAR-? with downregulation of AKT phosphorylation during adipocyte differentiation.Conclusions: Chitosan significantly inhibits inflammation and adipogenesis as well as related signaling pathways of orbital fibroblasts from GO.This indicates a possible therapeutic effect of chitosan on Graves ophthalmopathy.