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Waseem Ahamed Shihabuddeen, Yasuo Yanagi, Richard Yu Ming Chuan, Veluchamy A Barathi, Xiaomeng Wang, Gemmy Chui Ming Cheung; Detailed phenotypic investigation of HtrA1 transgenic mice model. Invest. Ophthalmol. Vis. Sci. 2021;62(8):268.
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© ARVO (1962-2015); The Authors (2016-present)
High-temperature requirement 1 (HtrA1) is linked with age-related macular degeneration(AMD)/polypoidal choroidal vasculopathy (PCV). Reportedly, polypoidal lesions, choroidal neovascularization(CNV) and lipid deposition are some of the common phenotypes of HtrA1 transgenic mice model. Moreover, overexpressed HtrA1 in mice RPE cells is associated with change in Bruch membrane composition. This study aims to clarify the phenotype of HtrA1 Tg mice in detail and to investigate the underlying pathophysiological mechanism of AMD and PCV.
In-vivo imaging was performed using funduscopy and optical coherence tomography (Micron,Phoenix), fluorescein angiography (FA: Micron), indocyanine green angiography (ICGA: HRA2, Heidelberg),and optical coherence tomography angiography (OCT-A: Plex Elite, Carl Zeiss). Eyes were sectioned or flat-mounted for Hematoxylin and eosin (H&E) and Immunofluorescence staining using CD31 (endothelial marker), APOE (drusen component), F4/80 (macrophage marker) and vitronectin antibodies to investigate the neovascularization, drusen formation, and infiltration of macrophage. Laser-induced CNV model was used to evaluate the role of HtrA1 on CNV activity.
We examined 60 Tg and 15 wild type aged mice (23 – 30 months). Abnormal subretinal lesions [(Tg -33% (20/60) and WT – 7% (1/15)] were detected on color fundus photography and OCT. ICGA images represent from middle to late phase hyperfluorescent nodules corresponding to the areas of white material deposition [Tg - 40% (4/10)], whereas no leakage was observed in FA. En-face OCT-A and cross-sectional OCT-A failed to confirm vascular flow signals. In addition, IHC stains showed no difference in APOE and CD31 between HtrA1 Tg and wild type mice groups which is supported by the mRNA sequencing data. From H&E stains, we confirmed that lesions are in fact RPE cell migrations. Retina and RPE flatmount demonstrated increase macrophage infiltration and activation in HtrA1 Tg mice. Laser induced CNV in young HtrA1 Tg mice(n=12 for HtrA1 and WT) showed increased leakage from CNV compared to wild type mice (P<0.05).
The subretinal lesions from mice have different composition compared to that of humans observed in PCV. Hence, these drusen-like deposits might be the representation of immune cells which have been migrated into the subretinal space. Such subclinical inflammation may have resulted in the increased activity of laser-induced CNV.
This is a 2021 ARVO Annual Meeting abstract.
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