Interaction of MMP-9 in the active phase of Graves' disease with and without ophthalmopathy

Thyroid eye disease (TED) is expressed as orbital inflammation, and serum levels of several proinflammatory cytokines have been studied among patients with Graves' disease (GD) with and without TED; however, a more sensitive and specific marker for the different phases of GD and TED is still lacking. Seventeen active TED, 16 inactive TED, 16 GD without TED, and 16 healthy controls were recruited. Serum IL-17A, MMP-2, MMP-3, and MMP-9 were measured by multiplex bead assay. TED hormone and eye parameters were evaluated, and their relationship with cytokine levels was analyzed. Serum MMP-9 was higher in active TED than healthy controls, whereas IL-17A was lower among these patients than in GD without TED and healthy controls. No differences were found in MMP-3 and MMP-2 concentrations. MMP-9 levels were lower in patients with inactive TED who underwent radioactive iodine (RAI) therapy and those on levothyroxine replacement. MMP-9 levels were elevated in patients on methimazole. A negative correlation was found between age at assessment and time of follow-up with MMP-9 levels in inactive TED. Free T3 and ophthalmometry values were positively correlated with MMP-9 in the GD without TED and inactive TED groups, respectively. In conclusion, serum MMP-9 was increased in patients with active TED and was related to the RAI treatment, longer follow-up time, and higher ophthalmometry in patients with inactive TED, as well as thyroid function in GD without TED. MMP-9 may be involved in both the active phase of TED and the active phase of inflammation related to GD.NEW & NOTEWORTHY Our study addresses clinical aspects of specific ophthalmological examination and serum cytokine concentrations of patients with Graves' disease (GD) with and without ophthalmopathy. Our findings suggest that MMP-9 may be involved in the active phase of ophthalmopathy and in the active phase of GD. The central question is whether MMP-9 is a potential target for future treatments.