Spinal IL-33/ST2 Signaling Contributes to Neuropathic Pain via Neuronal CaMKII-CREB and Astroglial JAK2-STAT3 Cascades in Mice.
BACKGROUND
Emerging evidence indicates that nerve damage-initiated neuroinflammation and immune responses, which are evidenced by the up-regulation of proinflammatory cytokines, contribute to the development of neuropathic pain. This study investigated the role of spinal interleukin (IL)-33 and its receptor ST2 in spared nerve injury (SNI)-induced neuropathic pain.


METHODS
The von Frey test and acetone test were performed to evaluate neuropathic pain behaviors (n = 8 to 12), and Western blot (n = 4 to 6), immunohistochemistry, real-time polymerase chain reaction (n = 5), and Bio-Plex (n = 5) assays were performed to understand the molecular mechanisms.


RESULTS
Intrathecal administration of ST2-neutralizing antibody or ST2 gene knockout (ST2) significantly attenuated the SNI-induced mechanical and cold allodynia. On the 7th day after SNI, the expression of spinal IL-33 and ST2 was increased by 255.8 ± 27.3% and 266.4 ± 83.5% (mean ± SD), respectively. Mechanistic studies showed that the increased expression of the spinal N-methyl-D-aspartate (NMDA) receptor subunit 1 after SNI was reduced by ST2 antibody administration or ST2. The induction of nociceptive behaviors in naive mice due to recombinant IL-33 was reversed by the noncompetitive NMDA antagonist MK-801. ST2 antibody administration or ST2 markedly inhibited the increased activation of the astroglial janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) cascade and the neuronal calcium-calmodulin-dependent kinase II (CaMKII)-cyclic adenosine monophosphate response element-binding protein (CREB) cascade after SNI. Moreover, intrathecal pretreatment with the CaMKII inhibitor KN-93 or the JAK2-STAT3 cascade inhibitor AG490 attenuated recombinant IL-33-induced nociceptive behaviors and NMDA subunit 1 up-regulation in naive mice.


CONCLUSIONS
Spinal IL-33/ST2 signaling contributes to neuropathic pain by activating the astroglial JAK2-STAT3 cascade and the neuronal CaMKII-CREB cascade.
From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institutes of Brain Science, Brain Science Collaborative Innovation Center, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
Shenbin
S
Liu
Wen-Li
WL
Mi
Qian
Q
Li
Meng-Ting
MT
Zhang
Ping
P
Han
Shan
S
Hu
Qi-Liang
QL
Mao-Ying
Yan-Qing
YQ
Wang
D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33 / Q000378:metabolism*; D053614:Janus Kinase 2 / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009437:Neuralgia / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D018123:Receptors, Interleukin / Q000172:deficiency / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; C486189:Il1rl1 protein, mouse; C506535:Il33 protein, mouse; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D018123:Receptors, Interleukin; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2