Abstract
Purpose: :
To compare cytokine levels in aqueous humor (AH) of patients with primary open angle glaucoma (POAG) and cataract patients.
Methods: :
AH samples were obtained from patients who underwent cataract or glaucoma procedures. AH cytokines were measured using multiplex cytometric bead array analysis. Freshly enucleated dog eyes were used to isolate ocular tissues. Human cadaver eyes and dog eyes free of glaucoma were fixed with 4% paraformaldehyde, embedded in paraffin and sectioned. Localization of IL-8 was determined by immunohistochemistry and by rtPCR.
Results: :
Sixty eyes from 46 cataract patients (32 patients with unilateral samples and 14 patients with bilateral samples) and 59 eyes from 40 POAG patients (21 patients with unilateral samples and 19 patients with bilateral samples) were identified retrospectively. Age, sex and gender were comparable between the two groups. Of 13 cytokines investigated, (IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12(p70), IL-13, IL-15, IL-18, IFN-gamma, and INF-alpha2), 5 cytokines (IL-10, IL-15, IL-18, IL-6 and IL-8) were detectable in AH. IL-8 was the only cytokine with significantly (p<0.0001) higher level in AH of POAG patients (5.54 pg/ml +3.96 pg/ml) compared with cataract patients (2.52 pg/ml +1.90 pg/ml). Paired bilateral samples from the control group (n=14) and 5 paired bilateral samples from patients with asymmetric glaucoma (3 with POAG and 2 with exfoliation glaucoma) were used to investigate correlation of IL-8 level with severity of glaucomatous optic nerve damage. IL-8 levels were similar in AH from pairs of control eyes (right vs. left: 2.6 pg/ml + 2.08 pg/ml vs. 2.6 pg/ml + 2.07 pg/ml; p = 0.95), but significantly elevated in AH from eyes with more severe glaucomatous optic nerve damage among asymmetric glaucoma patients (worse vs. better eye: 6.4 pg/ml + 2.69 pg/ml vs. 2.3 pg/ml + 1.62 pg/ml; p < 0.05). IL-8 mRNA was detected in dog sclera, uveal tissues, retina and optic nerve, and IL-8 protein was detected in ciliary body, retina and optic nerve.
Conclusions: :
IL-8 level is significantly higher in glaucomatous AH and is positively corrected with glaucoma severity.Supported by the Vanderbilt Vision Research Center; Research to Prevent Blindness Unrestricted Grant; The American Glaucoma Society.
Keywords: cytokines/chemokines • inflammation • aqueous