The Cytokine Interleukin-6 and the Chemokines CCL20 and CXCL13 Are Novel Biomarkers of Specific Endogenous Uveitic Entities

Abstract

Purpose: The purpose of this study was to determine levels of the cytokines IL-1β, IL-6, IL-21, IL-22, and IL-23 and the chemokines CXCL13, CCL19, CCL20, and CCL21 in aqueous humor (AH) samples from patients with specific uveitic entities.

Methods: Paired serum samples (n = 13) and AH samples (n = 111) from patients with active idiopathic granulomatous uveitis (IGU) or with uveitis associated with HLA-B27-related inflammation, Behçet's disease (BD), Vogt-Koyanagi-Harada (VKH) disease, or sarcoidosis and control patients were analyzed in two different multiplex assays.

Results: Cytokines IL-1β, IL-21, IL-22, and IL-23 were not detected in any AH sample. Chemokine CCL21 concentrations in serum were significantly higher than those in AH. CCL19 levels in AH and serum were not significantly different. Levels of CCL20 and CXCL13 in AH were significantly higher than those in serum. IL-6 was not detected in serum samples. IL-6 AH levels were significantly higher in patients with HLA-B27-associated uveitis and in BD patients than in patients with VKH disease, sarcoidosis, and IGU (P < 0.0001). CCL20 AH levels were significantly higher in HLA-B27-associated uveitis than in BD, VKH, sarcoidosis, and IGU (P = 0.001), whereas CXCL13 AH levels were significantly higher in VKH disease and IGU than in HLA-B27-associated uveitis, BD, and sarcoidosis (P = 0.007).

Conclusions: IL-6-driven immune responses are more potent in HLA-B27-associated uveitis and BD than in VKH disease, sarcoidosis, and IGU. CCL20 appears to be a specific biomarker of HLA-B27-associated uveitis, whereas CXCL13 appears to be a biomarker of VKH disease and IGU. Our findings suggest that IL-6, CCL20, and CXCL13 could serve as drug targets for treatment of specific clinical entities of endogenous uveitis.