Increase in peripheral blood mononuclear cell Toll-like receptor 2/3 expression and reactivity to their ligands in a cohort of patients with wet age-related macular degeneration

PURPOSE To investigate Toll-like receptor (TLR) expression and reactivity in patients with the wet form age-related macular degeneration (AMD). METHODS Blood samples were collected from 25 patients with wet AMD and 25 age-matched healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated with Ficoll-Hypaque density gradient centrifugation. Expression of TLR1 to TLR10 mRNAs in PBMCs from 15 patients with wet AMD and 15 controls was assessed with real-time PCR. TLR2 and TLR3 protein levels in PBMCs from six patients with wet AMD and six controls were measured with flow cytometry. After PBMCs were stimulated with peptidoglycan (PGN) and poly(I:C), the specific ligands of TLR2 and TLR3, cytokines interleukin-6 (IL-6), IL-8, VEGF, and monocyte chemoattractant protein-1 (MCP-1) production in 11 patients with wet AMD and 11 controls were assessed. RESULTS TLR2 and TLR3 mRNA and protein expression in the PBMCs of the patients with wet AMD was significantly higher than that in the controls. However, the difference in TLR1 and TLR4-10 mRNA expression between the two groups was not significant. The PBMCs of the patients with wet AMD produced more IL-6 and IL-8 proteins than the controls in response to PGN, a ligand for TLR2, and more IL-6 protein than the controls in response to poly(I:C), the ligand for TLR3. However, there was no significant difference in vascular endothelial growth factor and monocyte chemoattractant protein-1 production between the wet AMD group and the control group when the PBMCs were stimulated with PGN or poly(I:C). CONCLUSIONS Our data suggested that upregulation of TLR2 and TLR3 may be associated with the pathogenesis of wet AMD.