Theanine improves the function of dendritic cells via the downregulation of cyclooxygenase-2 expression.
BACKGROUND
Tumor cells can reduce the number of dendritic cells (DCs) in the tumor environment and cause DC dysfunction through autocrine or paracrine pathways. We sought to measure cyclooxygenase-2 (COX-2) expression in bombesin-inhibited DCs treated with theanine in vitro and to explore the protection and activation effects of theanine on DCs.


METHODS
Enzyme-linked immunosorbent assay (ELISA), reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting were used to analyze the effects of theanine on COX-2 expression and interleukin (IL)-12/IL-10 secretion of bombesin-treated DCs.


RESULTS
DCs acquired an impaired phenotype as a result of bombesin treatment. Theanine increased the expression of mature DC surface molecules. The number of cell apoptosis with the treatment of bombesin and theanine significantly decreased, accounting for 15.9%, compared with 26.1% of cell apoptosis with bombesin. COX-2 expression in bombesin-treated DCs was inhibited by theanine in a dose-dependent manner. Theanine promoted DC secretion of IL-12. IL-12 levels reached (137.4 ± 4.9) pg/ml with theanine at 200 µmol/L. However, theanine inhibited the secretion of IL-10 in a dose-dependent manner. IL-10 levels were only (58.4 ± 6.9) pg/ml with theanine at 200 µmol/L.


CONCLUSIONS
Theanine inhibits the transcription and translation of COX-2 and regulates the balance of IL-10/IL-12 secretion in bombesin-inhibited DCs, leading to the recovery of a state of activation in DCs.
Department of Respiratory and Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China; Department of Respiratory and Critical Care Medicine, Zhangjiajie City Hospital, Zhangjiajie, Hunan 427000, China.
Mingsheng
M
Lei
Medical School, University of South China, Hengyang, Hunan 421001, China.
Jianhong
J
Zuo
Department of Respiratory and Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
Min
M
Li
Department of Respiratory and Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
Qihua
Q
Gu
Department of Respiratory and Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China. Email: huchengp28@yahoo.com.cn.
Chengping
C
Hu
D001839:Bombesin / Q000494:pharmacology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D003713:Dendritic Cells / Q000187:drug effects* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005971:Glutamates / Q000494:pharmacology*; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D018664:Interleukin-12 / Q000378:metabolism
D005971:Glutamates; D016753:Interleukin-10; D018664:Interleukin-12; C026166:theanine; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D001839:Bombesin