Serum levels of chemokines correlate with disease activity in patients with retinal vasculitis

Retinal vasculitis (RV) is characterised pathologically by migration of leucocytes across the blood–retinal barrier leading to oedema and photoreceptor cell dysfunction. Chemokines are a family of small molecules involved in leucocyte migration. In this study, levels of chemokines were measured in serum from patients with RV and correlated with disease activity and drug treatment. Serum samples (n=100; 25 active, 75 inactive) were obtained from 50 patients with RV, and levels of the chemokines MIP-1α, macrophage inflammatory protein-1β (MIP-1β) and monocyte chemoattractant protein-1 (MCP-1) were measured by ELISA. For longitudinal analysis levels of the same chemokines were measured in six consecutive serum samples from 10 of the above patients. Chemokine levels were correlated with disease activity and current drug treatment for each sample. Sera from 20 healthy individuals were used as control samples. Serum levels of MIP-1β were significantly raised in patients with RV, whether active or not, compared to healthy controls (P=0.04). Levels of MIP-1β and MCP-1 correlated with disease activity in some patients and with prednisolone levels in patients on this treatment alone. MIP-1α levels were not detectable in all samples but were present in significantly more samples from patients with active or inactive RV compared with healthy controls. Serum levels of the chemokines MIP-1β and MIP-1α, but not MCP-1 were raised in patients with retinal vasculitis. Longitudinal analysis suggested that MIP-1β and MCP-1 levels were controlled by drug treatment, particularly prednisolone. These data demonstrate that chemokines are involved in the pathogenesis of RV and may act as novel therapeutic targets.