Changes of Serum Inflammatory Molecules and Their Relationships with Visual Function in Retinitis Pigmentosa

Abstract

Purpose: Retinal degeneration involves neuroinflammation, and pro-inflammatory cytokines/chemokines are markedly increased in the eyes of patients with retinitis pigmentosa (RP). In this study, we investigated the changes of serum cytokines/chemokines in RP, and their relationships with visual parameters.

Methods: Forty-five consecutive patients with typical RP aged 20 to -39 years and 28 age-matched and gender-matched controls were included. Fifteen cytokines (interleukin [IL]-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, IL-13, 1L-15, IL-17, IL-23, interferon [IFN]-γ, and tumor necrosis factor [TNF]-α, TNF-β) and 9 chemokines (eotaxin, growth-related oncogene [GRO]-α, I-309, IL-8, IFN-γ-inducible protein [IP]-10, monocyte chemotactic protein [MCP]-1, MCP-2, regulated activation normal T-cell expressed and secreted [RANTES], and thymus and activated regulated chemokine [TARC]) in the serum were simultaneously measured by a multiplexed immunoarray (Q-Plex). Relationships between these cytokines/chemokines and indices of central vision, such as visual acuity (VA), the values of static perimetry tests (Humphrey Field analyzer, the central 10-2 program), and optical coherence tomography measures were analyzed in the patients with RP.

Results: Among the 15 cytokines and 9 chemokines, serum IL-8 and RANTES levels were significantly increased in patients with RP compared with controls (IL-8: P < 0.0001; RANTES: P < 0.0001). Among the elevated cytokines/chemokines, the levels of IL-8 were negatively correlated with VA (ρ = 0.3596 and P = 0.0165), and the average retinal sensitivity of four central points (ρ = -0.3691 and P = 0.0291), and 12 central points (ρ = -0.3491 and P = 0.0398), as well as the central subfield thickness (ρ = -0.3961 and P = 0.0094), and ellipsoid zone width (ρ = -0.3841 and P = 0.0120).

Conclusions: Peripheral inflammatory response may be activated and serum IL-8 levels are associated with central vision in patients with RP.

Figure 1.

Relationships between the levels of serum interleukin (IL)-8 and visual function in patients with retinitis pigmentosa (RP). The scatterplot shows the levels of serum IL-8 and visual acuity (VA) (A), the MD values in Humphrey Field Analyzer (HFA) 10-2 tests (B), the average sensitivity of 4 central points (C), and the average sensitivity of 12 central points (D).

Figure 2.

Relationships between the levels of serum interleukin (IL)-8 and OCT parameters in patients with retinitis pigmentosa (RP). The scatterplot shows the relation between the levels of serum IL-8 and each of central subfield thickness (CST) (A) and the ellipsoid zone (EZ) width (B).