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Angiopoietin concentrations in diabetic retinopathy

J I Patel^1,2, P G Hykin¹, Z J Gregor¹, M Boulton³ and I A Cree²

¹ Moorfields Eye Hospital, London, UK
² Institute of Ophthalmology, London, UK
³ School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK

Correspondence to:
Correspondence to:
MrJ I Patel
Department of Pathology, Institute of Ophthalmology, 11–43 Bath Street, London EC1V 9EL, UK; jigs37{at}hotmail.com

Background/aim: Angiopoietin 1 and 2 interact with vascular endothelial growth factor (VEGF) to promote angiogenesis in animal and in vitro models. Although VEGF concentrations are elevated, there is little information regarding angiopoietin concentration in the vitreous of patients with diabetic retinopathy.

Methods: Angiopoietin concentrations were measured by luminescence immunoassay in vitreous samples from 17 patients with non-proliferative diabetic retinopathy (NPDR) and clinically significant diabetic macular oedema (CSMO), 10 patients with proliferative diabetic retinopathy (PDR), and five patients with macular hole (controls) obtained at pars plana vitrectomy.

Results: Angiopoietin 1 concentrations were low in patients with macular hole (median 17 pg/ml) while in NPDR with CSMO they were 2002 pg/ml (range 289–5820 pg/ml) and in PDR 186 pg/ml (range 26–2292 pg/ml). Angiopoietin 2 concentrations in NPDR with CSMO were a median of 4000 pg/ml (range 1341–14 329 pg/ml). For both macular hole and PDR patients angiopoietin 2 was below the limit of detection.

Conclusions: Angiopoietin 2 concentration was twice that of angiopoietin 1 in NPDR with CSMO. Angiopoietin 2 is the natural antagonist of angiopoietin 1 which is thought to act as an anti-permeability agent. The predominance of angiopoietin 2 may allow VEGF induced retinal vascular permeability in patients with CSMO. The relatively low concentration of both angiopoietin 1 and 2 in patients with proliferative diabetic retinopathy may reflect the established nature of the neovascularisation in cases proceeding to vitrectomy.

Abbreviations: BSA, bovine serum albumin; CSMO, clinically significant diabetic macular oedema; FAZ, foveolar avascular zone; FFA, fundus fluorescein angiography; FTMH, full thickness macular hole; LIA, luminescence immunoassay; NPDR, non-proliferative diabetic retinopathy; OCT, optical coherence tomography; PBS, phosphate buffer saline; PDR, proliferative diabetic retinopathy; VEGF, vascular endothelial growth factor

Keywords: diabetic retinopathy; angiopoietin

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