Melatonin promoted chemotaxins expression in lung epithelial cell stimulated with TNF-alpha.
BACKGROUND
Patients with asthma demonstrate circadian variations in the airway inflammation and lung function. Pinealectomy reduces the total inflammatory cell number in the asthmatic rat lung. We hypothesize that melatonin, a circadian rhythm regulator, may modulate the circadian inflammatory variations in asthma by stimulating the chemotaxins expression in the lung epithelial cell.


METHODS
Lung epithelial cells (A549) were stimulated with melatonin in the presence or absence of TNF-alpha(100 ng/ml). RANTES (Regulated on Activation Normal T-cells Expressed and Secreted) and eotaxin expression were measured using ELISA and real-time RT-PCR, eosinophil chemotactic activity (ECA) released by A549 was measured by eosinophil chemotaxis assay.


RESULTS
TNF-alpha increased the expression of RANTES (307.84 +/- 33.56 versus 207.64 +/- 31.27 pg/ml of control, p = 0.025) and eotaxin (108.97 +/- 10.87 versus 54.00 +/- 5.29 pg/ml of control, p = 0.041). Melatonin(10(-10) to 10(-6)M) alone didn't change the expression of RNATES (204.97 +/- 32.56 pg/ml) and eotaxin (55.28 +/- 6.71 pg/ml). However, In the presence of TNF-alpha (100 ng/ml), melatonin promoted RANTES (410.88 +/- 52.03, 483.60 +/- 55.37, 559.92 +/- 75.70, 688.42 +/- 95.32, 766.39 +/- 101.53 pg/ml, treated with 10(-10), 10(-9), 10(-8), 10(-7),10(-6)M melatonin, respectively) and eotaxin (151.95 +/- 13.88, 238.79 +/- 16.81, 361.62 +/- 36.91, 393.66 +/- 44.89, 494.34 +/- 100.95 pg/ml, treated with 10(-10), 10(-9), 10(-8), 10(-7), 10(-6)M melatonin, respectively) expression in a dose dependent manner in A549 cells (compared with TNF-alpha alone, P < 0.05). The increased release of RANTES and eotaxin in A549 cells by above treatment were further confirmed by both real-time RT-PCR and the ECA assay.


CONCLUSIONS
Taken together, our results suggested that melatonin might synergize with pro-inflammatory cytokines to modulate the asthma airway inflammation through promoting the expression of chemotaxins in lung epithelial cell.
Luo
FengMing
F
West China Hospital of Sichuan University, Chengdu, China. lufengming@hotmail.com
Liu
XiaoJing
X
Li
ShuangQing
S
Liu
ChunTao
C
Wang
ZengLi
Z
D002460:Cell Line; D054413:Chemokine CCL11; D018946:Chemokine CCL5 / Q000008:administration & dosage*; D019742:Chemokines, CC / Q000096:biosynthesis*; D002631:Chemotactic Factors, Eosinophil / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008550:Melatonin / Q000008:administration & dosage*; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage*
C515456:CCL11 protein, human; C515458:Ccl11 protein, rat; D054413:Chemokine CCL11; D018946:Chemokine CCL5; D019742:Chemokines, CC; D002631:Chemotactic Factors, Eosinophil; D004338:Drug Combinations; D014409:Tumor Necrosis Factor-alpha; D008550:Melatonin