Alpha-Lipoic Acid Ameliorates Radiation-Induced Lacrimal Gland Injury through NFAT5-Dependent Signaling

Dry eye syndrome related to radiation therapy is relatively common and can severely impair a patient's daily life. The nuclear factor of activated T cells 5(NFAT5) is well known for its osmoprotective effect under hyperosmolar conditions, and it also has immune-modulating functions. We investigated the role of NFAT5 and the protective effect of alpha-lipoic acid(ALA) on radiation-induced lacrimal gland (LG) injuries. Rats were assigned to control, ALA only, radiation only, and ALA administered prior to irradiation groups. The head and neck area, including the LG, was evenly irradiated with 2 Gy/minute using a photon 6-MV linear accelerator. NFAT5 expression was enhanced and localized in the LG tissue after irradiation and was related to cellular apoptosis. ALA had a protective effect on radiation-induced LG injury through the inhibition of NFAT5 expression and NFAT5-dependent signaling pathways. Functional radiation-induced damage of the LG and cornea was also restored with ALA treatment. NFAT5 expression and its dependent signaling pathways were deeply related to radiation-induced dry eye, and the condition was improved by ALA treatment. Our results suggest a potential role of NFAT5 and NF-kappa B in the proinflammatory effect in LGs and cornea, which offers a target for new therapies to treat dry eye syndrome.