Interleukin-6 protects annulus fibrosus cell from apoptosis induced by interleukin-1 beta in vitro.
OBJECTIVE
To investigate the effect of interleukin-6 (IL-6) on the apoptosis of annulus fibrosus (AF) cell induced by interleukin-1beta (IL-1beta).


METHODS
Cultured AF cells were divided into 6 groups and treated with no drug, 10 ng/mL IL-6, 10 ng/mL IL-1beta, 10 ng/mL IL-1beta and Z-VAD-FMK (a caspase-9 inhibitor), 10 ng/mL IL-1beta and 10 ng/mL IL-6, 10 ng/mL IL-1beta and 100 ng/mL IL-6, respectively. After three days of culture, the apoptosis rate, the positive rates of caspase-3, -8, and -9 of AF cells were detected with flow cytometry.


RESULTS
The apoptosis rates of cells in group 1 to 6 were 2.67% +/- 1.08%, 2.71% +/- 0.53%, 20.37% +/- 1.57%, 11.34% +/- 0.67%, 18.17% +/- 0.74%, and 9.42% +/- 1.08%, respectively. There was no significant difference between group 1 and 2, while the apoptosis rates of group 4, 5, and 6 were significantly lower than group 3 (P = 0.001, P = 0.172, and P = 0.001, respectively). Positive rates of caspase-3 in group 5 (12.35% +/- 0.64%) and 6 (9.26% +/- 0.36%) were significantly lower than group 3 (17.14% +/- 0.72%; P = 0.001 and P < 0.001, respectively). And positive rates of caspase-9 in group 5 (15.13% +/- 1.45%) and 6 (10.17% +/- 2.50%) were significantly lower than group 3 (19.4% +/- 0.98% ; P = 0.014 and P = 0.004, respectively). But there was not obvious change of caspase-8 activity after IL-6 was added.


CONCLUSIONS
IL-6 is capable of protecting AF cells from IL-1beta induced apoptosis in vitro. Mechanism of the protection is related with the inhibition of caspase-3 and -9 activities.
Duan
De-Yu
DY
Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022. duandeyu@21cn.com
Yang
Shu-Hua
SH
Xiong
Xiao-Qian
XQ
Shao
Zeng-Wu
ZW
Wang
Hong
H
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D007403:Intervertebral Disc / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D011817:Rabbits
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D053583:Interleukin-1beta; D015850:Interleukin-6; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone