IADR Abstract Archives
Epigallocatechin Gallate Protection in Salivary Gland Radiation Injury and Homeostasis
Objectives: Epigallocatechin gallate (EGCG) derived from Camelia sinensis leaves is a well-known antioxidant catechin. Our aim was to determine the biological protective effects of EGCG during homeostasis and radiation injury to salivary glands (SG).
Methods: Murine fetal ex vivo SG models were used and dose response studies conducted with EGCG 0.15-150µg/ml. For homeostasis conditions, SG were cultured for 48h to identify what EGCG dose range can support their epithelial bud growth or branching morphogenesis index (BMI). Next, SG were pre-treated with EGCG before irradiation (IR) injury, which was delivered using a linear accelerator with high energy photons (7Gy, 6MV, Varian Clinac iX), and 24-48h later the BMI was assessed. Whole-mount immunohistochemistry and quantitative PCR with Ki67, Sox2, KRT14 and AQP5 was performed to investigate whether EGCG modulates epithelial and stem/progenitor cell proliferation and differentiation. Griess assay was run for measuring reactive oxygen species (ROS) induced by IR before and after EGCG treatment. Data was statistically analyzed by one-way analysis of variance with Dunnet’s posthoc test with alpha level set at 0.05 using GraphPad Prism.
Results: EGCG 1.875-30µg/ml supported SG epithelial homeostasis and 7.5-15µg/ml EGCG prevented radiation-induced epithelial damage. In IR conditions, cellular mitosis (Ki67) was significantly increased with 7.5 and 15µg/ml EGCG at the acinar and ductal epithelial compartments when compared to non-treated SG controls; Sox2 was also highly expressed at both epithelial compartments but without statistical significance. SG ductal progenitor marker KRT14 and acinar marker AQP5 were significantly increased with EGCG 7.5µg/ml relative to non-treated SG. Moreover, EGCG 7.5µg/ml pre-treatment reduced the ROS generated by IR conditions.
Conclusions: EGCG at 7.5µg/ml can maintain epithelial homeostasis and proliferation through SG development. In IR injury models, 7.5µg/ml EGCG protected epithelial growth by increasing the proliferation of acinar and ductal progenitor cells, and producing greater antioxidant activity in the SG organ.
Methods: Murine fetal ex vivo SG models were used and dose response studies conducted with EGCG 0.15-150µg/ml. For homeostasis conditions, SG were cultured for 48h to identify what EGCG dose range can support their epithelial bud growth or branching morphogenesis index (BMI). Next, SG were pre-treated with EGCG before irradiation (IR) injury, which was delivered using a linear accelerator with high energy photons (7Gy, 6MV, Varian Clinac iX), and 24-48h later the BMI was assessed. Whole-mount immunohistochemistry and quantitative PCR with Ki67, Sox2, KRT14 and AQP5 was performed to investigate whether EGCG modulates epithelial and stem/progenitor cell proliferation and differentiation. Griess assay was run for measuring reactive oxygen species (ROS) induced by IR before and after EGCG treatment. Data was statistically analyzed by one-way analysis of variance with Dunnet’s posthoc test with alpha level set at 0.05 using GraphPad Prism.
Results: EGCG 1.875-30µg/ml supported SG epithelial homeostasis and 7.5-15µg/ml EGCG prevented radiation-induced epithelial damage. In IR conditions, cellular mitosis (Ki67) was significantly increased with 7.5 and 15µg/ml EGCG at the acinar and ductal epithelial compartments when compared to non-treated SG controls; Sox2 was also highly expressed at both epithelial compartments but without statistical significance. SG ductal progenitor marker KRT14 and acinar marker AQP5 were significantly increased with EGCG 7.5µg/ml relative to non-treated SG. Moreover, EGCG 7.5µg/ml pre-treatment reduced the ROS generated by IR conditions.
Conclusions: EGCG at 7.5µg/ml can maintain epithelial homeostasis and proliferation through SG development. In IR injury models, 7.5µg/ml EGCG protected epithelial growth by increasing the proliferation of acinar and ductal progenitor cells, and producing greater antioxidant activity in the SG organ.