Abstract
Purpose :
Corneal lymphangiogenesis is a well-known player in the pathogenesis of dry eye disease (DED). This study is to evaluate the expression of known angiogenic factors related with lymph-/hem-angiogenesis in the cornea, conjunctiva, and lacrimal gland in the murine DED model with controlled environmental chamber (CEC).
Methods :
DED was induced by housing 9-week-old female C57BL/6 mice in a CEC that allowed for the relative low humidity (< 25%), continuous regulation of airflow, and temperature (21 to 23°C) for 3 weeks. Corneal fluorescein score was evaluated to confirm the efficacy of DED induction. Fluorescence images from the corneal whole mounts after immunohistochemical stain for lymphatic vessel endothelial hyaluronan receptor (lyve)-1 were used for analysis. The expression of m-RNA of the VEGF-A, VEGF-C, VEGF-D (Figf), Angiopoietin-2 (Angpt2), VEGFR3 (Flt4), and Substance P (Tac1) were evaluated by real-time PCR in the cornea, conjunctiva, and lacrimal gland.
Results :
Percentage of the area of lyve-1+ area of the whole corneal area increased significantly in DED group (P=0.015, Mann-Whitney U test). The expression of mRNA of the angiogenic factors were increased significantly in cornea, conjunctiva and lacrimal gland in different pattern. In cornea, all the factors except VEGFR3 showed earlier response at day 2, increased significantly compared with control (1.5~3.5 folds increase, each P<0.05, One way ANOVA), whereas VEGFR3 showed delayed response at day14 and VEGF-C/-D showed sustained increase until day 14. In conjunctiva, all the factors except Angiopoietin-2 showed significant increase at day 7 (1.6~4.8 folds, each P<0.05) and then normalized. In lacrimal glands, Substance P and VEGF-D showed sustained increase during induction period (1.8~6.8 folds) and VEGF-A/-C, Angiopoietin-2 showed early, short responses at day 2 and/or day 7 (1.6~13.6 folds).
Conclusions :
Expression of angiogenic factors showed different clustered expression patterns according to the tissue and duration of dry eye induction. The most prominent and prolonged change was observed in the lacrimal glands, which indicates the possibility of a path through the tear in the effect of angiogenic factors on cornea. However, the exact interaction and mode of action of these factors should be studied further.
This is a 2020 ARVO Annual Meeting abstract.