Whole orbital tissue culture identifies imatinib mesylate and adalimumab as potential therapeutics for Graves' ophthalmopathy

Background and aims Biologicals and small inhibitory molecules are used to treat inflammatory diseases, but their efficacy varies upon clinical application. Using a whole orbital tissue culture system, we tested the potential efficacy of imatinib mesylate (a tyrosine kinase inhibitor that blocks platelet-derived growth factor (PDGF)-receptor, c-Abl and c-Kit activity) and adalimumab (an anti-TNF-alpha antibody) for the treatment of Graves' ophthalmopathy (GO). Methods Orbital fat tissue from GO patients (n=10) was cultured with or without imatinib mesylate or adalimumab. PDGF-B and tumour necrosis factor (TNF)-alpha mRNA expression levels were determined in the primary orbital tissue, and interleukin (IL)-6 and hyaluronan were measured in tissue-culture supernatants. Results Imatinib mesylate significantly (p=0.005) reduced IL-6 and hyaluronan production. The inhibition of hyaluronan production correlated positively and significantly (p<0.05) with the PDGF-B mRNA level in the primary tissue. Adalimumab also significantly (p=0.005) reduced IL-6 production. The amount of IL-6 inhibition correlated positively with the TNF-alpha mRNA level in the primary tissue, but this was not significant. Conclusions Imatinib mesylate can be expected to reduce inflammation and tissue remodelling in GO, while adalimumab can be mainly expected to reduce inflammation. This in vitro tissue-culture model may, in future, prove valuable to test novel therapeutics for their presumed effect in GO as well as in other inflammatory diseases.