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We endeavored to identify objective blood biomarkers for pain, a subjective sensation with a biological basis, using a stepwise discovery, prioritization, validation, and testing in independent cohorts design. We studied psychiatric patients, a high risk group for co-morbid pain disorders and increased perception of pain. For discovery, we used a powerful within-subject longitudinal design. We were successful in identifying blood gene expression biomarkers that were predictive of pain state, and of future emergency department (ED) visits for pain, more so when personalized by gender and diagnosis. MFAP3, which had no prior evidence in the literature for involvement in pain, had the most robust empirical evidence from our discovery and validation steps, and was a strong predictor for pain in the independent cohorts, particularly in females and males with PTSD. Other biomarkers with best overall convergent functional evidence for involvement in pain were GNG7, CNTN1, LY9, CCDC144B, and GBP1. Some of the individual biomarkers identified are targets of existing drugs. Moreover, the biomarker gene expression signatures were used for bioinformatic drug repurposing analyses, yielding leads for possible new drug candidates such as SC-560 (an NSAID), and amoxapine (an antidepressant), as well as natural compounds such as pyridoxine (vitamin B6), cyanocobalamin (vitamin B12), and apigenin (a plant flavonoid). Our work may help mitigate the diagnostic and treatment dilemmas that have contributed to the current opioid epidemic.
Learn More >Based on few clinical trials, flunarizine is considered a first-line prophylactic treatment for migraine in several guidelines. In this meta-analysis, we examined the pooled evidence for its effectiveness, tolerability, and safety. Prospective randomized controlled trials of flunarizine as a prophylaxis against migraine were identified from a systematic literature search, and risk of bias was assessed for all included studies. Reduction in mean attack frequency was estimated by calculating the mean difference (MD), and a series of secondary outcomes-including adverse events (AEs)-were also analyzed. The database search yielded 879 unique records. Twenty-five studies were included in data synthesis. We scored 31/175 risk of bias items as "high," with attrition as the most frequent bias. A pooled analysis estimated that flunarizine reduces the headache frequency by 0.4 attacks per 4 weeks compared with placebo (5 trials, 249 participants: MD -0.44; 95% confidence interval -0.61 to -0.26). Analysis also revealed that the effectiveness of flunarizine prophylaxis is comparable with that of propranolol (7 trials, 1151 participants, MD -0.08; 95% confidence interval -0.34 to 0.18). Flunarizine also seems to be effective in children. The most frequent AEs were sedation and weight increase. Meta-analyses were robust and homogenous, although several of the included trials potentially suffered from high risk of bias. Unfortunately, reporting of AEs was inconsistent and limited. In conclusion, pooled analysis of data from partially outdated trials shows that 10-mg flunarizine per day is effective and well tolerated in treating episodic migraine-supporting current guideline recommendations.
Learn More >Orosensory thermal trigeminal afferent neurons respond to cool, warm, and nociceptive hot temperatures with the majority activated in the cool range. Many of these thermosensitive trigeminal orosensory afferent neurons also respond to capsaicin, menthol and/or mustard oil (allyl isothiocyanate, AITC) at concentrations found in foods and spices. There is significant but incomplete overlap between afferent trigeminal neurons that respond to heat and to the above chemesthetic compounds. Capsaicin sensitizes warm trigeminal thermoreceptors and orosensory nociceptors; menthol attenuates cool thermoresponses.
Learn More >Osteoarthritis, the leading cause of chronic joint pain, is studied through different animal models, but none of them is ideal in terms of reliability and translational value. In this pilot study of female rats, 3 surgical models of osteoarthritic pain, destabilization of the medial meniscus (DMM), cranial cruciate ligament transection (CCLT), and the combination of both surgical models (COMBO) and 1 chemical model [intra-articular injection of monosodium iodoacetate (MIA)] were compared for their impact on functional pain outcomes [static weight-bearing (SWB) and punctate tactile paw withdrawal threshold (PWT)] and spinal neuropeptides [substance P (SP), calcitonin gene-related peptide (CGRP), bradykinin (BK), and somatostatin (SST)]. Six rats were assigned to each model group and a sham group. Both the chemical model (MIA) and surgical COMBO model induced functional alterations in SWB and PWT, with the changes being more persistent in the surgical combination group. Both models also produced an increase in levels of pro-nociceptive and anti-nociceptive neuropeptides at different timepoints. Pain comparison with the MIA model showed the advantage of a surgical model, especially the combination of the DMM and CCLT models, whereas each surgical model alone only led to temporary functional alterations and no change in neuropeptidomics.
Learn More >To examine the hypothesis that surprising experiences of headache triggers are associated with daily headache activity.
Learn More >The aim of the present study was to further elucidate the role of JAK2/STAT3-CAV-1-NR2B on painful diabetic neuropathy.
Learn More >Most drug epidemics in the United States have disproportionately affected nonwhite communities. Notably, the current opioid epidemic is heavily concentrated among low-income white communities, and the roots of this racial/ethnic phenomenon have not been adequately explained.
Learn More >Fibromyalgia (FM) is a chronic illness characterised by the presence of generalised musculoskeletal pain among other symptoms, which reduce the quality of life of the patient. Clinical interventions such as patient education on central pain management could lead to promising results. The aim of this study is to evaluate the effectiveness of education techniques on the main symptoms such as pain, quality of life, anxiety, functionality or catastrophisation in the treatment of FM.
Learn More >Migraine is a debilitating disease that affects almost 15% of the population worldwide and is the first cause of disability in people under 50 years of age, yet its etiology and pathophysiology remain incompletely understood. Recently, small molecules and therapeutic antibodies that block the calcitonin gene-related peptide (CGRP) signaling pathway have reduced migraine occurrence and aborted acute attacks of migraine in clinical trials and provide prevention in patiens with episodic and chronic migraine. Heterogeneity is present within each diagnosis and a patient's response to treatment, suggesting migraine as a final common pathway potentially activated by multiple mechanisms, e.g. not all migraine attacks respond or are prevented by anti-CGRP pharmacological interventions. Consequently, other unique mechanisms central to migraine pathogenesis may present new targets for drug development. Pituitary adenylate cyclase-activating peptide (PACAP) is an attractive novel target for treatment of migraines. We generated a specific, high affinity, neutralizing monoclonal antibody (ALD1910) with reactivity to both PACAP38 and PACAP27. In vitro, ALD1910 effectively antagonizes PACAP38 signaling through the PAC1-R, VPAC1-R, and VPAC2-R. ALD1910 recognizes a non-linear epitope within PACAP and blocks its binding to the cell surface. To test ALD1910 antagonistic properties directed against endogenous PACAP, we developed an umbellulone-induced rat model of neurogenic vasodilation and parasympathetic lacrimation. In vivo, this model demonstrates that the antagonistic activity of ALD1910 is dose-dependent, retaining efficacy at doses as low as 0.3 mg/kg. These results indicate that ALD1910 represents a potential therapeutic antibody to address PACAP-mediated migraine.
Learn More >Pain has a useful protective role; through avoidance learning, it helps to decrease the probability of engaging in tissue-damaging, or otherwise dangerous experiences. In our modern society, the experience of acute post-surgical pain and the development of chronic pain states represent an unnecessary negative outcome. This has become an important health issue as more than 30% of the US population reports experiencing "unnecessary" pain at any given time. Opioid therapies are often efficacious treatments for severe and acute pain; however, in addition to their powerful analgesic properties, opioids produce potent reinforcing properties and their inappropriate use has led to the current opioid overdose epidemic in North America. Dissecting the allostatic changes occurring in nociceptors and neuronal pathways in response to pain are the first and most important steps in understanding the physiologic changes underlying the opioid epidemic. Full characterization of these adaptations will provide novel targets for the development of safer pharmacotherapies. In this review, we highlight the current efforts toward safer opioid treatments and describe our current knowledge of the interaction between pain and opioid systems.
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