Bailing Hou

The inhibitor of calcium/calmodulin-dependent protein kinase II KN93 attenuates bone cancer pain via inhibition of KIF17/NR2B trafficking in mice

The N-methyl-d-aspartate receptor (NMDAR) containing subunit 2B (NR2B) is critical for the regulation of nociception in bone cancer pain, although the precise molecular mechanisms remain unclear. KIF17, a kinesin motor, plays a key role in the dendritic transport of NR2B. The up-regulation of NR2B and KIF17 transcription results from an increase in phosphorylated cAMP-response element-binding protein (CREB), which is activated by calcium/calmodulin-dependent protein kinase II (CaMKII). In this study, we hypothesized that CaMKII-mediated KIF17/NR2B trafficking may contribute to bone cancer pain. Osteosarcoma cells were implanted into the intramedullary space of the right femurs of C3H/HeJ mice to induce progressive bone cancer-related pain behaviors. The expression of spinal t-CaMKII, p-CaMKII, NR2B and KIF17 after inoculation was also evaluated. These results showed that inoculation of osteosarcoma cells induced progressive bone cancer pain and resulted in a significant up-regulation of p-CaMKII, NR2B and KIF17 expression after inoculation. Intrathecal administration of KN93, a CaMKII inhibitor, down-regulated these three proteins and attenuated bone cancer pain in a dose- and time-dependent manner. These findings indicated that CaMKII-mediated KIF17/NR2B trafficking may contribute to bone cancer pain, and inhibition of CaMKII may be a useful alternative or adjunct therapy for relieving cancer pain.

CREB-regulated transcription coactivator 1 enhances CREB-dependent gene expression in spinal cord to maintain the bone cancer pain in mice.

Background cAMP response element binding protein (CREB)-dependent gene expression plays an important role in central sensitization. CREB-regulated transcription coactivator 1 (CRTC1) dramatically increases CREB-mediated transcriptional activity. Brain-derived neurotrophic factor, N-methyl-d-aspartate receptor subunit 2B, and miRNA-212/132, which are highly CREB responsive, function downstream from CREB/CRTC1 to mediate activity-dependent synaptic plasticity and in turn loops back to amplify CREB/CRTC1 signaling. This study aimed to investigate the role of spinal CRTC1 in the maintenance of bone cancer pain using an RNA interference method. Results Osteosarcoma cells were implanted into the intramedullary space of the right femurs of C3H/HeNCrlVr mice to induce bone cancer pain. Western blotting was applied to examine the expression of spinal phospho-Ser133 CREB and CRTC1. We further investigated effects of repeated intrathecal administration with Adenoviruses expressing CRTC1-small interfering RNA (siRNA) on nociceptive behaviors and on the upregulation of CREB/CRTC1-target genes associated with bone cancer pain. Inoculation of osteosarcoma cells induced progressive mechanical allodynia and spontaneous pain, and resulted in upregulation of spinal p-CREB and CRTC1. Repeated intrathecal administration with Adenoviruses expressing CRTC1-siRNA attenuated bone cancer–evoked pain behaviors, and reduced CREB/CRTC1-target genes expression in spinal cord, including BDNF, NR2B, and miR-212/132. Conclusions Upregulation of CRTC1 enhancing CREB-dependent gene transcription in spinal cord may play an important role in bone cancer pain. Inhibition of spinal CRTC1 expression reduced bone cancer pain. Interruption to the positive feedback circuit between CREB/CRTC1 and its targets may contribute to the analgesic effects. These findings may provide further insight into the mechanisms and treatment of bone cancer pain.

The effects of dexmedetomidine pretreatment on the pro- and anti-inflammation systems after spinal cord injury in rats

Excessive inflammatory responses play important roles in the aggravation of secondary damage to an injured spinal cord. Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist, has recently been implied to be neuroprotective in clinical anesthesia, but the underlying mechanism is elusive. As signaling through Toll-like receptor 4 (TLR4) and nicotinic receptors (nAChRs, notably α7nAChR) play important roles in the pro- and anti-inflammation systems in the central nervous system, respectively, this study investigated whether and how they were modulated by DEX pretreatment in a rat model of spinal cord compression. The model was used to mimic perioperative compressive spinal cord injury (SCI) during spinal correction. DEX preconditioning improved locomotor scores after SCI, which was accompanied by increased α7nAChR and acetylcholine (Ach, an endogenous ligand of α7nAChR) expression as well as PI3K/Akt activation. However, there was a decrease in Ly6h (a negative regulator for α7nAChR trafficking), TLR4, PU.1 (a critical transcriptional regulator of TLR4), HMGB1 (an endogenous ligand of TLR4), and caspase 3-positive cells, which was prevented by intrathecal preconditioning with antagonists of either α2R, α7nAChR or PI3K/Akt. In addition, application of an α7nAChR agonist produced effects similar to those of DEX after SCI, while application of an α7nAChR antagonist reversed these effects. Furthermore, both α7nAChR and TLR4 were mainly co-expressed in NeuN-positive cells of the spinal ventral horn, but not in microglia or astrocytes after SCI. These findings imply that the α2R/PI3K/Akt/Ly6h and α7nAChR/PI3K/Akt/PU.1 cascades are required for upregulated α7nAChR and downregulated TLR4 expression by DEX pretreatment, respectively, which provided a unique insight into understanding DEX-mediated neuroprotection.

Positive feedback regulation between microRNA-132 and CREB in spinal cord contributes to bone cancer pain in mice

cAMP response element‐binding protein (CREB)‐dependent gene expression plays an important role in central sensitization. CREB‐regulated transcription coactivator 1 (CRTC1) dramatically increase CREB‐mediated transcriptional activity. microRNA‐132 (miR‐132), which is highly CREB‐responsive, functions downstream from CREB/CRTC1 to mediate activity‐dependent synaptic plasticity and in turn loops back to amplify CREB/CRTC1 signalling. This study aimed to investigate the positive feedback regulation between miR‐132 and CREB in spinal cord in the maintenance of bone cancer pain.

Kinesin superfamily protein 17 contributes to the development of bone cancer pain by participating in NR2B transport in the spinal cord of mice

Τreatment of bone cancer pain remains a challenge, while the mechanisms causing the pain remain elusive. We demonstrated that the expression of the N‑methyl‑D‑aspartate (NMDA) receptor NR2B subunit was upregulated in mice with bone cancer pain. Kinesin superfamily protein 17 (KIF17), a recently characterized member of the kinesin superfamily proteins, has been demonstrated to transport and deliver the NR2B subunit to dendrites in mammalian neurons. In the present study, we induced bone cancer pain via femur bone cavity osteosarcoma NCTC 2472 tumor cell implantation (TCI) in mice. The results showed that TCI in mice increased the number of spontaneous flinches, mechanical allodynia events, expression of spinal KIF17 and NR2B subunits. Intrathecal administration of KIF17 antisense oligodeoxynucleotide (ODN) attenuated the behavioral signs of bone cancer pain and suppressed the increased expression of NR2B induced by TCI. In addition, KIF17 binds to a protein complex that contains mLin‑10 to transport NR2B, and we determined that the increase of mLin‑10 was suppressed following admini-stration. Thus, these findings suggested that KIF17 contributed to the development of bone cancer pain in the spinal cord through NR2B transport and that mLin‑10 may also play a role in pain development.

The activation of spinal astrocytes contributes to preoperative anxiety-induced persistent post-operative pain in a rat model of incisional pain

Preoperative anxiety, a clinically significant problem for many patients undergoing surgery, is associated with prolonged and exacerbated post‐operative pain. To date, the mechanisms of preoperative anxiety‐induced persistent post‐operative pain remain unclear. The present study aimed to provide a rat model of preoperative anxiety‐induced persistent post‐operative pain using the single‐prolonged stress (SPS) procedure to induce preoperative anxiety‐like behaviours, and to explore the role of spinal astrocytes in this phenomenon.

Mas-Related Gene (Mrg) C Activation Attenuates Bone Cancer Pain via Modulating Gi and NR2B.

Objective This study is to investigate the role of Mas-related gene (Mrg) C in the pathogenesis and treatment of bone cancer pain (BCP). Methods BCP mouse model was established by osteosarcoma cell inoculation. Pain-related behaviors were assessed with the spontaneous lifting behavior test and mechanical allodynia test. Expression levels of MrgC, Gi, and NR2B in the spinal cord were detected with Western blot analysis and immunohistochemistry. Results Pain-related behavior tests showed significantly increased spontaneous flinches (NSF) and decreased paw withdrawal mechanical threshold (PWMT) in mouse models of BCP. Western blot analysis showed that, compared with the control group and before modeling, all the expression levels of MrgC, Gi, and NR2B in the spinal cord of BCP mice were dramatically elevated, which were especially increased at day 7 after operation and thereafter, in a time-dependent manner. Moreover, the treatment of MrgC agonist BAM8-22 significantly up-regulated Gi and down-regulated NR2B expression levels, in the spinal cord of BCP mice, in a time-dependent manner. On the other hand, anti-MrgC significantly down-regulated Gi expression, while dramatically up-regulated NR2B expression, in the BCP mice. Similar results were obtained from the immunohistochemical detection. Importantly, BAM8-22 significantly attenuated the nociceptive behaviors in the BCP mice. Conclusion Our results indicated the MrgC-mediated Gi and NR2B expression alterations in the BCP mice, which might contribute to the pain hypersensitivity. These findings may provide a novel strategy for the treatment of BCP in clinic.

Association between intraoperative hypotension and 30-day mortality, major adverse cardiac events, and acute kidney injury after non-cardiac surgery: A meta-analysis of cohort studies

BACKGROUND The association between intraoperative hypotension (IOH) and postoperative outcomes is not fully understood. We performed a meta-analysis to determine whether IOH is associated with increased risk of 30-day mortality, major adverse cardiac events (MACEs) and acute kidney injury (AKI) after non-cardiac surgery. METHODS We searched PubMed and Embase through May 2016 to identify cohort studies that investigated the association between IOH and risk of 30-day mortality, MACEs, or AKI in adult patients after non-cardiac surgery. Ascertainment of IOH and assessment of outcomes were defined by the individual study. Considering the level of clinical heterogeneity, adjusted odds ratios (ORs) with 95% confidence interval (CIs) were pooled using a random-effects model. This meta-analysis is registered on PROSPERO (CRD42016049405). RESULTS We included 14 cohort studies that were heterogeneous in terms of definition of IOH. IOH alone was associated with increased risk of 30-day mortality (OR 1.29 [95% CI, 1.19-1.41]), MACEs (OR 1.59 [95% CI, 1.23-2.05]), especially myocardial injury (OR 1.67 [95% CI, 1.31-2.13]), and AKI (OR 1.39 [95% CI, 1.09-1.77]). Triple low (IOH coincident with low bispectral index and low minimum alveolar concentration) also predicts increased risk of 30-day mortality (OR 1.32 [95% CI, 1.03-1.68]). CONCLUSIONS IOH alone significantly increases the risk of postoperative 30-day mortality, MACEs, especially myocardial injury, and AKI in adult patients after non-cardiac surgery. Triple low also predicts increased risk of 30-day mortality after non-cardiac surgery. These findings provide evidence that IOH should be recognized as an independent risk factor for postoperative adverse outcomes after non-cardiac surgery.