TIE1 and TEK signalling, intraocular pressure, and primary open-angle glaucoma: a Mendelian randomization study

Skanda Rajasundaram; Nazlee Zebardast; Puja Mehta; Anthony P Khawaja; Alasdair Warwick; Katherine Duchinski; Stephen Burgess; Dipender Gill; Ayellet V Segrè; Janey Wiggs

doi:10.1186/s12967-023-04737-9

TIE1 and TEK signalling, intraocular pressure, and primary open-angle glaucoma: a Mendelian randomization study

J Transl Med. 2023 Nov 24;21(1):847. doi: 10.1186/s12967-023-04737-9.

Authors

Skanda Rajasundaram^{1

2}, Nazlee Zebardast^{3

4}, Puja Mehta^{5

6

7}, Anthony P Khawaja⁸, Alasdair Warwick^{8

9}, Katherine Duchinski^{3

4

5}, Stephen Burgess⁸, Dipender Gill⁹, Ayellet V Segrè^#^{10

3

4}, Janey Wiggs^#^{3

4

5}

Affiliations

¹ Faculty of Medicine, Imperial College London, London, UK. skandarajasundaram@gmail.com.
² Department of Ophthalmology, Harvard Medical School, Boston, MA, USA. skandarajasundaram@gmail.com.
³ Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
⁴ Ocular Genomics Institute, Massachusetts Eye and Ear, Boston, MA, USA.
⁵ Broad Institute of MIT and Harvard, Cambridge, MA, USA.
⁶ NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK.
⁷ UCL Institute of Cardiovascular Science, London, UK.
⁸ MRC Biostatistics Unit, University of Cambridge, Cambridge, UK.
⁹ Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
¹⁰ Faculty of Medicine, Imperial College London, London, UK.

^# Contributed equally.

Abstract

Background: In primary open-angle glaucoma (POAG), lowering intraocular pressure (IOP) is the only proven way of slowing vision loss. Schlemm's canal (SC) is a hybrid vascular and lymphatic vessel that mediates aqueous humour drainage from the anterior ocular chamber. Animal studies support the importance of SC endothelial angiopoietin-TEK signalling, and more recently TIE1 signalling, in maintaining normal IOP. However, human genetic support for a causal role of TIE1 and TEK signalling in lowering IOP is currently lacking.

Methods: GWAS summary statistics were obtained for plasma soluble TIE1 (sTIE1) protein levels (N = 35,559), soluble TEK (sTEK) protein levels (N = 35,559), IOP (N = 139,555) and POAG (N_cases = 16,677, N_controls = 199,580). Mendelian randomization (MR) was performed to estimate the association of genetically proxied TIE1 and TEK protein levels with IOP and POAG liability. Where significant MR estimates were obtained, genetic colocalization was performed to assess the probability of a shared causal variant (PP_shared) versus distinct (PP_distinct) causal variants underlying TIE1/TEK signalling and the outcome. Publicly available single-nucleus RNA-sequencing data were leveraged to investigate differential expression of TIE1 and TEK in the human ocular anterior segment.

Results: Increased genetically proxied TIE1 signalling and TEK signalling associated with a reduction in IOP (- 0.21 mmHg per SD increase in sTIE1, 95% CI = - 0.09 to - 0.33 mmHg, P = 6.57 × 10^-4, and - 0.14 mmHg per SD decrease in sTEK, 95% CI = - 0.03 to - 0.25 mmHg, P = 0.011), but not with POAG liability. Colocalization analysis found that the probability of a shared causal variant was greater for TIE1 and IOP than for TEK and IOP (PP_shared/(PP_distinct + PP_shared) = 0.98 for TIE1 and 0.30 for TEK). In the anterior segment, TIE1 and TEK were preferentially expressed in SC, lymphatic, and vascular endothelium.

Conclusions: This study provides novel human genetic support for a causal role of both TIE1 and TEK signalling in regulating IOP. Here, combined evidence from cis-MR and colocalization analyses provide stronger support for TIE1 than TEK as a potential IOP-lowering therapeutic target.

Keywords: Colocalization; Intraocular pressure; Mendelian randomization; Primary open-angle glaucoma; TEK; TIE1.

Publication types

Research Support, Non-U.S. Gov't
Research Support, N.I.H., Extramural

MeSH terms

Angiopoietins
Animals
Glaucoma, Open-Angle* / drug therapy
Glaucoma, Open-Angle* / genetics
Humans
Intraocular Pressure* / genetics
Mendelian Randomization Analysis

Substances

Angiopoietins

Abstract

Publication types

MeSH terms

Substances

Grants and funding