Autophagy and Hsp70 activation alleviate oral epithelial cell death induced by food-derived hypertonicity

• Published in: Cell stress & chaperones Vol. 25; no. 2; pp. 253 - 264
• Main Authors: Yang, Ji, Zhang, Huijie, Sun, Sujiao, Wang, Xue, Guan, Ying, Mi, Qili, Zeng, Wanli, Xiang, Haiying, Zhu, Huadong, Zou, Xin, You, Yunfei, Xiang, Yang, Gao, Qian
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Science + Business Media 01-03-2020; Springer Netherlands; Springer Nature B.V
• Subjects: Adult; Apoptosis; Autophagy; Autophagy - drug effects; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cancer Research; Cell activation; Cell Biology; Cell death; Cell Line; Cell survival; Chewing; Crosstalk; Epithelial cells; Epithelial Cells - cytology; Epithelial Cells - metabolism; Epithelium; Female; Food; Food industry; Food processing industry; Glucose; Glucose - chemistry; Healthy Volunteers; HSP70 Heat-Shock Proteins - physiology; Hsp70 protein; Humans; Hypertonicity; Immunology; Male; Mortality; Mouth Mucosa - cytology; Mouth Mucosa - metabolism; Neurosciences; Oral hygiene; ORIGINAL PAPER; Osmolar Concentration; Osmolarity; Osmotic Pressure; Phagocytosis; Plant extracts; Sodium chloride; Sodium Chloride - chemistry; Stimulation; Stress response; Terpenes - pharmacology; Time dependence; Young Adult; Heat shock proteins; Hypertonic; Osmolarity; Autophagy; Handelin; Mouth
• ISSN: 1355-8145; 1466-1268
• DOI: 10.1007/s12192-020-01068-2

Stable intracellular and intercellular osmolarity is vital for all physiological processes. Although it is the first organ that receives food, the osmolarity around the mouth epithelium has never been systematically investigated. We found that oral epithelial cells are a population of ignored cells routinely exposed to hypertonic environments mainly composed of saline, glucose, etc. in vivo after chewing food. By using cultured oral epithelial cells as an in vitro model, we found that the hypotonic environments caused by both high NaCl and high glucose induced cell death in a dose- and time-dependent manner. Transcriptomics revealed similar expression profiles after high NaCl and high glucose stimulation. Most of the common differentially expressed genes were enriched in “mitophagy” and “autophagy” according to KEGG pathway enrichment analysis. Hypertonic stimulation for 1 to 6 h resulted in autophagosome formation. The activation of autophagy protected cells from high osmolarity-induced cell death. The activation of Hsp70 by the pharmacological activator handelin significantly improved the cell survival rate after hypertonic stimulation. The protective role of Hsp70 activation was partially dependent on autophagy activation, indicating a crosstalk between Hsp70 and autophagy in hypertonic stress response. The extract of the handelin-containing herb Chrysanthemum indicum significantly protected oral epithelial cells from hypertonic-induced death, providing an inexpensive way to protect against hypertonic-induced oral epithelial damage. In conclusion, the present study emphasized the importance of changes in osmolarity in oral health for the first time. The identification of novel compounds or herbal plant extracts that can activate autophagy or HSPs may contribute to oral health and the food industry.