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Chronic low back pain (cLBP) is a prevalent disorder. A growing body of evidence linking the pathology of the reward network to chronic pain suggests that pain sensitization may contribute to cLBP chronification via disruptions of mesocortical and mesolimbic circuits in the reward system. Resting-state (RS) functional magnetic resonance imaging (fMRI) data was acquired from 90 patients with cLBP and 74 matched pain-free controls (HCs) at baseline and after a manipulation for back pain intensification. The ventral tegmental area (VTA) was chosen as a seed region to perform RS functional connectivity (FC) analysis. Baseline rsFC of both the mesocortical (between the VTA and bilateral rostral anterior cingulate cortex (rACC) / and medial prefrontal cortex (mPFC)) and mesolimbic (between the VTA and bilateral hippocampus/parahippocampus) pathways was reduced in patients with cLBP (vs. HCs). In addition, patients exhibiting higher back pain intensity (compared to the relatively lower back pain intensity condition) also showed increases in both mesocortical and mesolimbic connectivity, implicating these pathways in pain downregulation in cLBP. Mediation analysis further isolated the mesolimbic (VTA-hippocampus/ parahippocampus) dysconnectivity as a neural mechanism mediating the association between mechanical pain sensitivity (indexed by P40 pressure) and cLBP severity. In sum, the current study demonstrates deficient mesocorticolimbic connectivity in cLBP, with the mesolimbic dysconnectivity potentially mediating the contribution of pain sensitization to pain chronification. These reward network dysfunctions and purportedly, dopaminergic dysregulations, may help us to identify key brain targets of neuromodulation in the treatment of cLBP.
There is ample evidence for the role of the immune system in developing chronic pain following peripheral nerve injury. Especially Toll-like receptors (TLRs) and their associated signaling components and pro-inflammatory cytokines such as IL-1β, induced after injury, are involved in nociceptive processes and believed to contribute to the manifestation of chronic neuropathic pain states. Whereas the inhibition of the kinase function of IRAK-4, a central kinase downstream of TLRs and IL-1 receptors (IL-1Rs), seems efficacious in various chronic inflammatory and autoimmune models, it's role in regulating chronic neuropathic pain remained elusive to date. Here, we examined whether pharmacological inhibition of IRAK-4 kinase activity using PF-06650833 and BMS-986147, two clinical-stage kinase inhibitors, is effective for controlling persistent pain following nerve injury. Both inhibitors potently inhibited TLR-triggered cytokine release in human peripheral blood mononuclear cell (PBMC) as well as human and rat whole blood cultures. BMS-986147 showing favorable pharmacokinetic (PK) properties, significantly inhibited R848-triggered plasma TNF levels in a rat in vivo cytokine release model after single oral dosing. However, BMS-986147 dose dependently reversed cold allodynia in a rat chronic constriction injury (CCI) model following intrathecal administration only, supporting the notion that central neuro-immune modulation is beneficial for treating chronic neuropathic pain. Although both inhibitors were efficacious in inhibiting IL-1β- or TLR-triggered cytokine release in rat dorsal root ganglion cultures, only partial efficacy was reached in IL-1β-stimulated human glial cultures indicating that inhibiting IRAK-4́s kinase function might be partially dispensable for human IL-1β driven neuroinflammation. Overall, our data demonstrate that IRAK-4 inhibitors could provide therapeutic benefit in chronic pain following nerve injury, and the central driver for efficacy in the neuropathic pain model as well as potential side effects of centrally available IRAK-4 inhibitors warrant further investigation to develop effective analgesia for patients in high unmet medical need.
Neck pain is a global burdensome problem, with a large proportion of neck pain cases becoming chronic. Although physical exercise is a commonly prescribed treatment, the evidence on the effectiveness of isolated exercise interventions remains limited. Traditional pairwise randomised controlled trials (RCTs) and meta-analyses are limited in only comparing two interventions. This protocol describes the design of a network meta-analysis, which enables a comparative investigation of all physical exercise interventions for which RCTs are available. We aim to systematically compare the effectiveness of different types of physical exercise in people with chronic non-specific neck pain.
Aim was to stratify the knee MRIs of the Foundation for National Institutes of Health Osteoarthritis Biomarkers Consortium (FNIH) cohort into distinct structural phenotypes based on semiquantitative assessment and to determine risk for pain and structural progression over 48 months.
Joint pain is the major clinical symptom of arthritis that affects millions of people. Controlling the excitability of knee-innervating dorsal root ganglion (DRG) neurons (knee neurons) could potentially provide pain relief. Therefore, our objective was to evaluate whether the newly engineered adeno-associated virus (AAV) serotype, AAV-PHP.S, can deliver functional artificial receptors to control knee neuron excitability following intra-articular knee injection.
Atopic dermatitis (AD) is associated with itch, pain, and sleep disturbance, all of which may contribute toward cognitive dysfunction.
Deafferentation pain (DP), a typical neuropathic pain, occurs due to peripheral or central sensory nerve injury, which causes abnormal discharge of the upstream neurons or C fibers. Current treatment methods for DP have multiple side effects. Bone marrow mesenchymal stem cells (BMSC) have been used to treat neuropathic pain because of their ability to regulate neuroinflammation. Glial cell-derived neurotrophic factor (GDNF) is a neurotrophic mediator that exerts neuroprotective effects in neurological diseases. In this study, we investigated whether DP could be alleviated by BMSCs and the underlying mechanism. In vitro study, microglia was stimulated by lipopolysaccharide and then co-cultured with BMSC, GDNF or siRNA GDNF-BMSC. In vivo study, BMSC or siRNA GDNF-BMSC was transplanted intramedullarily on the 21st day after DP surgery. The expression of inflammatory-related factors were detected by RT-PCR and ELISA, RT-PCR,flow cytometry and immunofluorescence staining were performed to detect the expression of microglial surface markers, and Western blot was used to detect the expression levels of p-NF-kb, pPI3K, and pAKT. The pain-related behavioral changes were detected 7 days after transplantation. ELISA and RT-PCR results showed that the production of inflammatory cytokines in lipopolysaccharide-stimulated microglia and DP model plasma was downregulated, while anti-inflammatory mediators were upregulated significantly following pretreatment with BMSCs or GDNF. Flow cytometry, immunofluorescence staining, and RT-PCR results showed that BMSCs inhibited the microglial M1 phenotype and promoted the M2 phenotype by secreting GDNF. Furthermore, modulation functions of BMSCs involve inhibiting NF-κB while promoting PI3K /AKT signaling pathway activation. We found that our in vivo DP model was completely deafferent and BMSC administration clearly alleviated symptoms of DP. This function was also, at least partly, achieved by GDNF. The present studies demonstrate that BMSC can inhibit neuroinflammation by transforming microglial destructive M1 phenotype into regenerative M2 phenotype, and thus alleviate DP,likely by suppressing the NF-κB signaling pathway while promoting the PI3K/AKT signaling pathway activation through producing GDNF. The present findings are in support of the potential therapeutic application of BMSCs and the pharmaceutical application of GDNF for DP.
Recently, the adenosine triphosphate (ATP) sensitive potassium channel opener levcromakalim was shown to induce migraine attacks with a far higher incidence than any previous provoking agent such as calcitonin gene-related peptide. Here, we show efficacy of ATP sensitive potassium channel inhibitors in two validated rodent models of migraine.
Previous studies regarding the quantitative sensory testing are inconsistent in migraine. We hypothesized that the quantitative sensory testing results were influenced by headache frequency or migraine phase.
Chronic low back pain (CLBP) is a highly prevalent and disabling condition in the elderly, and yet it is undertreated and understudied in this patient population. Tapentadol is a central analgesic with an improved tolerability profile that may be particularly beneficial to the elderly CLBP.