Abstract
Purpose :
Loss of function variants in ANGPTL7 are associated with lower intraocular pressure (IOP) and protection from multiple forms of glaucoma. ANGPTL7 is highly expressed in trabecular meshwork cells, the prominent cell type in the conventional outflow tract where outflow resistance and IOP is regulated. Here we examine the effect of a novel anti-ANGPTL7 antibody on outflow facility in perfused human donor eyes.
Methods :
Anti-ANGPTL7 IgGs were created, tested for efficacy in a 3D cell culture and rabbit models and then analyzed by epitope mapping. Peptide scanning of the epitope maps confirmed that they recognized the fibrinogen domain of ANGPTL7, suggesting that this domain is important for regulation of IOP by ANGPTL7. To monitor the effect of epitope-mapped anti-ANGPTL7 IgGs on outflow facility in human eyes (n=6), we used our specifically designed metabolic perfusion chambers in conjunction with iPerfusion software. Human donor eyes were obtained from the Miracles in Sight Eye Bank/BioSight Tissue Repository. Anterior chambers were cannulated with two 25-gauge needles, one placed under the iris and connected to a pressure reservoir for maintaining constant pressure, and the other placed in the anterior chamber and connected to an exchange reservoir. Eyes were perfused for 60 min at constant pressure of 15 mmHg to acclimate/establish stable outflow facility, while measuring flow over time. One eye was exchanged with 5 ml of anti-ANGPTL7 IgGs (40 µg/ml), and the other exchanged with 5 ml of isotype IgGs (40 µg/ml) as a control. Perfusion was continued in the presence of respective IgGs for 3 hours. Statistical analysis was performed using paired t-tests.
Results :
Outflow facility (reported as isotype IgGs vs anti-ANGPTL7 IgGs) in human eyes perfused with anti-ANGPTL7 IgGs at a constant pressure of 15mmHg showed 61% increase in facility at 2 hours (0.24±0.10 vs. 0.39±0.15 µl/min/mmHg, p=0.0011) and a 58% increase at 3 hours (0.24±0.10 vs. 0.39±0.12 µl/min/mmHg , p<0.0001), with 1 hour trending towards an increase in facility (0.23±0.06 vs. 0.43±0.22 µl/min/mmHg, a 88% increase, p=0.058).
Conclusions :
Inhibition of ANGPTL7 with IgGs rapidly and robustly increases outflow facility in human donor eyes compared to the paired contralateral control eyes. Data suggests that ANGPTL7 plays a key role in outflow resistance regulation, and represents a valuable target for treatment of ocular hypertension in glaucoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.