αVβ8 integrin- a potential druggable target to prevent posterior capsular opacification (PCO)

Abstract

Purpose : Fibrotic posterior capsular opacification (PCO), the major post cataract surgery (PCS) complication, is driven by transforming growth factor β (TGFβ) signaling. However, the mechanisms that activate the TGFβ pathway PCS are not well understood. Previously, we found that αV-integrins are critical for the activation of TGFβ signaling in fibrotic PCO pathogenesis. Here we identify the functionally important β subunit that heterodimerizes with αV-integrin to drive fibrotic PCO, and test whether blocking its function is an efficacious PCO preventative.

Methods : Mice lacking β8 integrin from the lens (β8ITG cKO) and wildtype controls were subjected to lens fiber cell removal which mimics cataract surgery. The dynamic localization of epithelial-mesenchymal transition (EMT) markers (α smooth muscle actin, fibronectin, tenascin C, collagen I), a fiber cell marker (aquaporin 0), a proliferation marker (ki67) and a downstream marker of canonical TGFβ signaling (pSMAD3) were determined by immunolocalization. RNAseq was performed on RNA isolated from lens epithelial cells (LCs) of control and β8ITG cKO mice at 0 hr. & 24 hrs. PCS. ADWA-11, an αVβ8 integrin blocking antibody, was administered to wildtype mice PCS to evaluate its potential to inhibit fibrotic PCO.

Results : β8ITG cKO LCs proliferated less, and did not undergo a qualitative fibrotic response PCS. This was associated with highly attenuated canonical TGFβ signaling PCS while the addition of active TGFβ to β8ITG cKO eyes PCS rescued both the TGFβ signaling defect and fibrotic responses. RNAseq found that a total of 834 genes exhibited altered expression levels in β8ITG cKO LCs at 24 hrs. PCS compared to control. These include key fibrotic and inflammatory markers and a profibrotic regulator, gremlin-1. The αVβ8 integrin antagonist ADWA-11 blocks TGFβ signaling and subsequent fibrotic responses at 3 days PCS in wildtype mice, a response that was maintained through 5 days PCS.

Conclusions : Blocking αVβ8 integrin function can prevent LC fibrosis PCS as it ameliorates TGFβ activation and fibrotic response by LCs PCS. These results suggest that ADWA-11 or related αVβ8 integrin function blocking reagents could be effective therapeutics preventing PCO development.

This is a 2020 ARVO Annual Meeting abstract.