Inflammation-related cells in the acqueous humour of patients affected by retinitis pigmentosa

Abstract

Purpose : Recent clinical and laboratory evidence supports a possible role of inflammation in the pathogenesis of retinitis pigmentosa (RP). The present study aims to evaluate the possible presence of inflammatory cells in patients affected by RP with flow cytometric analysis of aqueous humour.

Methods : Our study included 9 patients affected by RP undergoing cataract surgery. Patients underwent a complete ophthalmological examination, fundus colour photography, optical coherence tomography (OCT), Goldmann kinetic perimetry, electroretinographic testing (ERG) and genetic testing.Subsequently, we performed flow cytometric analysis of the aqueous humour samples collected during cataract surgery and a peripheral blood (PB) sample. Flow cytometric analysis of both samples provided membrane staining targeting surface molecules, and an intracytoplasmic staining, targeting cytokines. The evaluation of surface molecules (namely CD16, CD14, CD19, CD3, CD4, CD8, CD161) permitted the identification of monocytes, NK, B, T cells, and T cells subpopulation.

Results : In all the aqueous humour (AH) samples from RP patients we found the presence of infiltrating leucocytes with lympho-monocytes characteristics, consisting of T lymphocytes (CD3+, both CD4+ and CD8+), B lymphocytes (CD19+), natural killer cells (CD16+CD3-) and monocytes (CD14+). Particularly the frequency of each infiltrating cell subset in AH was comparable to that of peripheral blood (PB) mononuclear cells(MNC) of the same patient: CD3+ 45.6% ±4.4 in PB and 49.6% ± 6.1 in AH; CD19+ 7.3% ±0.8 in PB and 5.5% ± 1.1 in AH; CD16+ 7.8% ± 1.9 in PB and 5.7% ±1.5 in AH; CD14+ 18% ± 2.6 in PB and 16.8% ± 3.5 in AH (mean value of 9 biological samples ± SE). Moroever, among CD3+ T lymphocytes, the frequency of CD3+CD4+ T cells subset showed a trend to reduction in AH compared to PBMNC even if the difference was no statistically significant (p=0.08 t test): CD4+ 61% ± 3.8 in PB and 46% ± 6 in AH (mean value of 9 biological samples ± SE).

Conclusions : The detection of inflammatory cells in the acqueus humour of patients with RP is consistent with the hypothesis of a possible role of inflammation in the pathogenesis of the disease. These findings suggest a possible future role for anti-inflammatory therapies to potentially control the clinical progression of retinal dystrophies.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.