OC 49.1 - 3K3A-Activated Protein C treatment exerts anti-inflammatory and blood barrier stabilizing effects in the retina, and inhibits choroidal neovascularization

Monday, June 26, 2023

14:45 – 15:00 ET

Room: 515

Session Available As: On-Demand

Presenting Author(s)

Tami Livnat, Prof. (she/her/hers)

Head - Basic Research Laboratory, Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheb
Tel Aviv University
Tel Aviv, Tel Aviv, Israel

Co-Author(s)

YW

Yehonatan Weinberger

MD
Rabin Medical Center, Ophthalmology Department and Laboratory of Eye Research Felsenstein Medical Research Center, Petah-Tikva, Israel
Petah-Tikva, Tel Aviv, Israel
JF

José A Fernández

MD Phd
Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA
San Diego, California, United States
GB

Gil Ben-David

MD
Rabin Medical Center, Ophthalmology Department and Laboratory of Eye Research Felsenstein Medical Research Center, Petah-Tikva, Israel
Petah-Tikva, Tel Aviv, Israel
DP

Dahlia Palevski

MD Phd
Rabin Medical Center, Ophthalmology Department and Laboratory of Eye Research Felsenstein Medical Research Center, Petah-Tikva, Israel
Petah-Tikva, Tel Aviv, Israel
IB

Ivan Budnik

MD Phd
University of IOWA
Iowa city, Iowa, United States
Sarina Levy-Mendelovich, MD

Senior Pediatric Hemato-oncologist
The National Hemophilia Center, and Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Ramat Gan, Israel
Tel Aviv, HaMerkaz, Israel
YN

Yael Nisgav

Msc
Rabin Medical Center, Ophthalmology Department and Laboratory of Eye Research Felsenstein Medical Research Center, Petah-Tikva, Israel
Petah-Tikva, Tel Aviv, Israel
DW

Dov Weinberger

MD
Rabin Medical Center, Ophthalmology Department and Laboratory of Eye Research Felsenstein Medical Research Center, Petah-Tikva, Israel
Petah-Tikva, Tel Aviv, Israel
Gili Kenet, MD

Director
The National Hemophilia Center, and Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer, Tel Aviv University, Tel Aviv, Israel
Yehud-Monosson, HaMerkaz, Israel
JG

John H. Griffin

Phd
Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA
San Diego, California, United States

Background: Choroidal neovascularization (CNV) is a major cause of vision loss in neovascular age-related macular degeneration (nAMD). Blood-retina barrier (BRB) disruption and inflammation exacerbate the progression of nAMD. There is an unmet need for pleiotropic agents to tighten the BRB, impede inflammation, and preserve vision. 3K3A-Activated Protein C (APC) is a recombinant variant of the physiological anticoagulant APC with cytoprotective properties. We previously demonstrated that 3K3A-APC treatment inhibits CNV growth and reduces vascular endothelial growth factor (VEGF) levels. Moreover, we confirmed the anti-inflammatory properties of 3K3A-APC in the retina using a posterior inflammation murine model.

Aims: To study the ability of 3K3A-APC to inhibit inflammation and stabilize the BRB in a CNV murine model.

Methods: CNV was triggered in C57BL/6J mice by laser and confirmed by fluorescein angiography (FA). Murine recombinant 3K3A-APC was injected intravitreally. Inflammatory cell recruitment was determined in retinal flatmounts using myeloid anti-CD11b and microglial anti-Ib1a antibodies. NLRP3 inflammasome activation was assessed by immunostaining of cryosections with anti-NLRP3 and anti-IL-1β antibodies. Retinal blood barrier integrity was studied by tracing Zonula Occludens 1 (ZO1) in LPS-triggered eyes. CNV volume and vascular penetration were evaluated using 3D confocal imaging of FITC-dextran.

Results: 3K3A-APC treatment significantly decreased myeloid and microglia cell number and recruitment to the retinal pigment epithelium (RPE)-choroid area (Figure 1). 3K3A-APC treatment inhibited inflammasome activation, determined by lower levels of NLRP3 and its downstream effector IL-1β. ZO1 clustering in the RPE border, noted in 3K3A-APC treated eyes, suggests a barrier protective effect of 3K3A-APC on outer BRB. 3K3A-APC treatment limited the leakage and induced regression of CNV.

Conclusion(s): Our results suggest that 3K3A‐APC may modulate CNV progression by suppressing inflammation and tightening the BRB.
Our data and the 3K3A-APC clinical safety profile suggest that 3K3A-APC should be considered a new therapeutic option for retinal disease.

Learning Objectives:

Describe the impact of 3K3A-APC treatment on myeloid and microglia cell activation and recruitment in the context of choroidal neovascularization.
Analyze the role of the NLRP3 inflammasome, IL-1β, and VEGF in the development of CNV and how 3K3A-APC treatment affects their levels.
Evaluate the use of fluorescein angiography as a surrogate marker for in vivo evaluation of the efficacy of 3K3A-APC treatment against leaking CNV lesions.