Cancer-associated pain is debilitating. Understanding the mechanisms that cause it can inform drug development that may improve quality of life in patients. Here, we found that the reduced abundance of potassium channels called TRESK in dorsal root ganglion (DRG) neurons sensitized nociceptive sensory neurons and cancer-associated pain. Overexpressing TRESK in DRG neurons suppressed tumor-induced neuronal hyperexcitability and pain hypersensitivity in bone metastasis model rats, whereas knocking down TRESK increased neuronal hyperexcitability and pain hypersensitivity in normal rats. Mechanistically, tumor-associated production of vascular endothelial growth factor (VEGF) activated the receptor VEGFR2 on DRGs, which increased the abundance of the calcineurin inhibitor DSCR1, which, in turn, decreased calcineurin-mediated activation of the transcription factor NFAT, thereby reducing the transcription of the gene encoding TRESK. Intrathecal application of exogenous calcineurin to tumor-bearing rats rescued TRESK abundance and abrogated both DRG hyperexcitability and pain hypersensitivity, whereas either inhibition or knockdown of calcineurin in normal rats reduced TRESK abundance and increased DRG excitability and pain sensitivity. These findings identify a potentially targetable mechanism that may cause bone metastasis–associated pain in cancer patients.

Since the mid-1980s, there has been a resurgence of severe forms of invasive group A streptococcal (GAS) disease in many countries and regions. However, there has not been any systemic epidemiologic analysis of GAS disease reported in mainland China. To analyse the molecular epidemiology of GAS disease, 86 strains from patients in different regions of mainland China were collected. The collection sites included blood, pus, wounds, the epipharynx and other sites. A total of 21 different emm types were identified in the isolates. In both invasive and non-invasive isolates, M1 (29?1 %) and M12 (23?3 %) were the most prevalent types, a different distribution to M type distributions reported in other countries. Furthermore, minor emm gene sequence alterations were noted for six types. Several important GAS virulence factors were detected by PCR using specific primers. The speB and slo genes were detected in all isolates and were species specific. Four superantigen genes, speA, speC, smeZ and ssa, were found in 52 % (45/86), 51 % (44/86), 82 % (71/86) and 23 % (27/86) of isolates, respectively. M1 isolates harboured more speA (84 %) and fewer speC genes (44 %), while M12 isolates had fewer speA (35 %) and more speC genes (100 %). There was also an association between some virulence genes and isolation sites, perhaps due to the correlation between the emm type distribution and virulence gene occurrence. For two important virulence genes related to necrotizing fasciitis, the sil gene was only carried by 11 of 86 isolates, and no sil gene contained the start codon ATA. The sla gene rarely occurred in GAS isolates, only four of 86 GAS strains being positive, including two isolates obtained from blood. In antimicrobial susceptibility tests, the overall rate of drug resistance in GAS isolates was higher than reported rates in other countries, and the resistance rates to erythromycin, tetracycline and clindamycin were 91?8, 93?4 and 80 %, respectively. This epidemiological study may help to understand the pathogenesis of GAS disease and aid in vaccine development.

Previously we have demonstrated that brain-derived neurotrophic factor (BDNF) contributes to spinal long-term potentiation (LTP) and pain hypersensitivity through activation of GluN2B-containing N-methyl-D-aspartate (GluN2B-NMDA) receptors in rats following spinal nerve ligation (SNL). However, the molecular mechanisms by which BDNF impacts upon GluN2B-NMDA receptors and spinal LTP still remain unclear. In this study, we first documented that Fyn kinase-mediated phosphorylation of GluN2B subunit at tyrosine 1472 (pGluN2B) was involved in BDNF-induced spinal LTP and pain hypersensitivity in intact rats. Second, we revealed a co-localization of Fyn and GluN2B-NMDA receptor in cultured dorsal horn neurons, implying that Fyn is a possible intermediate kinase linking BDNF/TrkB signaling with GluN2B-NMDA receptors in the spinal dorsal horn. Furthermore, we discovered that both SNL surgery and intrathecal active Fyn could induce an increased expression of dorsal horn pGluN2B, as well as pain hypersensitivity in response to von Frey filaments stimuli; and more importantly, all these actions were effectively abrogated by pre-treatment with either PP2 or ifenprodil to respectively inhibit Fyn kinase and GluN2B-NMDA receptors activity. Moreover, we found that intrathecal administration of BDNF scavenger TrkB-Fc prior to SNL surgery, could prevent the nerve injury-induced increase of both pFyn and pGluN2B expression, and also inhibit the mechanical allodynia in neuropathic rats. Collectively, these results suggest that Fyn kinase-mediated pGluN2B is critical for BDNF-induced spinal LTP and pain hypersensitivity in SNL rats. Therefore, the BDNF-Fyn-GluN2B signaling cascade in the spinal dorsal horn may constitute a key mechanism underlying central sensitization and neuropathic pain development after peripheral nerve injury.

Outbreaks in humans, caused by Streptococcus suis serotype 2 (SS2), were reported in 1998 and 2005 in China. However, the mechanism of SS2-associated infection remains unclear. For the first time, a 2-D gel approach combined with MS was used to establish a comprehensive 2-D reference map for aiding our understanding of the pathogenicity of SS2. The identification of 694 out of 834 processed spots revealed 373 proteins. Most of the identified proteins were located in the cytoplasm and were involved in energy metabolism, protein synthesis, and cellular processes. Proteins that were abundant in the 2-DE gels could be linked mainly to housekeeping functions in carbohydrate metabolism, protein quality control and translation. 2-DE of secretory proteins was performed using IPG strips of pH 4-7. Among the 102 protein spots processed, 87 spots representing 77 proteins were successfully identified. Some virulence-associated proteins of SS2 were found, including arginine deiminase, ornithine carbamoyl-transferase, carbamate kinase, muramidase-released protein precursor, extracellular factor, and suilysin. Enolase and endopeptidase have been proposed as putative virulence-associated factors in this study. The 2-D reference map might provide a powerful tool for analyzing the virulence factor and the regulatory network involved in the pathogenicity of this microorganism.

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Peripheral nerve functional recovery after injuries relies on both axon regeneration and remyelination. Both axon regeneration and remyelination require intimate interactions between regenerating neurons and their accompanying Schwann cells. Previous studies have shown that motor and sensory neurons are intrinsically different in their regeneration potentials. Moreover, denervated Schwann cells accompanying myelinated motor and sensory axons have distinct gene expression profiles for regeneration-associated growth factors. However, it is unknown whether differential motor and sensory functional recovery exists. If so, the particular one among axon regeneration and remyelination responsible for this difference remains unclear. Here, we aimed to establish an adult rat sciatic nerve crush model with the nonserrated microneedle holders and measured rat motor and sensory functions during regeneration. Furthermore, axon regeneration and remyelination was evaluated by morphometric analysis of electron microscopic images on the basis of nerve fiber classification. Our results showed that Aα fiber-mediated motor function was successfully recovered in both male and female rats. Aδ fiber-mediated sensory function was partially restored in male rats, but completely recovered in female littermates. For both male and female rats, the numbers of regenerated motor and sensory axons were quite comparable. However, remyelination was diverse among myelinated motor and sensory nerve fibers. In detail, Aβ and Aδ fibers incompletely remyelinated in male, but not female rats, whereas Aα fibers fully remyelinated in both sexes. Our result indicated that differential motor and sensory functional recovery in male but not female adult rats is associated with remyelination rather than axon regeneration after sciatic nerve crush.

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Cancer-associated pain is debilitating. However, the mechanism underlying cancer-induced spontaneous pain and evoked pain remains unclear. Here, using behavioral tests with immunofluorescent staining, overexpression, and knockdown of TRESK methods, we found an extensive distribution of TRESK potassium channel on both CGRP+ and IB4+ nerve fibers in the hindpaw skin, on CGRP+ nerve fibers in the tibial periosteum which lacks IB4+ fibers innervation, and on CGRP+ and IB4+ dorsal root ganglion (DRG) neurons in rats. Moreover, we found a decreased expression of TRESK in the corresponding nerve fibers within the hindpaw skin, the tibial periosteum and the DRG neurons in bone cancer rats. Overexpression of TRESK in DRG neurons attenuated both cancer-induced spontaneous pain (partly reflect skeletal pain) and evoked pain (reflect cutaneous pain) in tumor-bearing rats, in which the relief of evoked pain is time delayed than spontaneous pain. In contrast, knockdown of TRESK in DRG neurons produced both spontaneous pain and evoked pain in naïve rats. These results suggested that the differential distribution and decreased expression of TRESK in the periosteum and skin, which is attributed to the lack of IB4+ fibers innervation within the periosteum of the tibia, probably contribute to the behavioral divergence of cancer-induced spontaneous pain and evoked pain in bone cancer rats. Thus, the assessment of spontaneous pain and evoked pain should be accomplished simultaneously when evaluating the effect of some novel analgesics in animal models. Also, this study provides solid evidence for the role of peripheral TRESK in both cancer-induced spontaneous pain and evoked cutaneous pain.