Circulating regulatory T cells as biomarkers for macular edema associated with non-infectious uveitis

Abstract

Purpose: To evaluate the profile of circulating levels of regulatory T cells (Treg) in patients with macular edema (ME) related to non-infectious uveitis and its relationship with central retinal thickness (CRT), anatomical classification, and therapeutical management.

Methods: Twenty-one patients with ME associated with non-infectious uveitis and 10 healthy subjects from 3 tertiary referral centers in Spain were included. Blood samples were obtained at baseline (T0) when patients presented with ME (considered as CRT > 300 μm, measured by optical coherence tomography [OCT]) and also when ME improved after treatment (T1, CRT <300 μm). Peripheral blood mononuclear cells (PBMCs) were obtained by Ficoll gradient from heparinized blood and Treg (CD3⁺CD4⁺Foxp3+CD25^hi) levels in PBMCs were determined by flow cytometry.<br />

Results: Patients with ME at T0 had significantly lower Treg levels than controls (2.08±0.24 % vs. 3.13±0.39 %, P<0.05). Resolution of ME seemed to be accompanied by an increase in Treg levels, although the difference did not reach statistical significance (T0 2.08±0.24 %, vs T1 2.98±0.83 %, P=0.247). Remarkably, patients who received systemic immunomodulatory therapy (IMT) showed a significant increase in Treg levels compared to those who received local therapy (dexamethasone intravitreal implant, periocular triamcinolone injection), (82±40 % improvement vs. -17±7 %, P<0.05).<br />

Conclusions: Our preliminary data suggest that Treg levels may serve as biomarkers of ME associated with non-infectiuos uveitis, as patients with ME showed reduced levels of Treg compared to healthy subjects. Moreover, ME resolution appeared to correlate with an increase in Treg levels, particularly in those patients receiving systemic IMT.