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Monoclonal antibodies against calcitonin gene-related peptide (CGRP) or its receptor are efficacious for the prevention of migraine headaches. The downstream molecular mechanisms following ligand-receptor blockade by which these antibodies prevent CGRP signaling through CGRP receptors have not been demonstrated.
Learn More >Using structure- and ligand-based design principles, a novel series of piperidyl chromane arylsulfonamide Na1.7 inhibitors was discovered. Early optimization focused on improvement of potency through refinement of the low energy ligand conformation and mitigation of high in vivo clearance. An in vitro hepatotoxicity hazard was identified and resolved through optimization of lipophilicity and LLE to arrive at GNE-616 (24), a highly potent, metabolically stable, subtype selective inhibitor of Na1.7. Compound 24 showed a robust PK/PD response in a Na1.7 dependent mouse model and site-directed mutagenesis was used to identify residues critical for the isoform selectivity profile of 24.
Learn More >CC chemokine receptor 2 (CCR2) is a part of the chemokine receptor family, an important class of therapeutic targets. These class A G-protein coupled receptors (GPCRs) are involved in mammalian signaling pathways and control cell migration toward endogenous CC chemokine ligands, named for the adjacent cysteine motif on their N terminus. Chemokine receptors and their associated ligands are involved in a wide range of diseases and thus have become important drug targets. CCR2, in particular, promotes the metastasis of cancer cells and is also implicated in autoimmunity-driven type-1 diabetes, diabetic nephropathy, multiple sclerosis, asthma, atherosclerosis, neuropathic pain, and rheumatoid arthritis. Although promising, CCR2 antagonists have been largely unsuccessful to date. Here, we investigate the effect of an orthosteric and an allosteric antagonist on CCR2 dynamics by coupling long-timescale molecular dynamics simulations with Markov-state model theory. We find that the antagonists shift CCR2 into several stable inactive conformations that are distinct from the crystal structure conformation and disrupt a continuous internal water and sodium ion pathway, preventing transitions to an active-like state. Several metastable conformations present a cryptic drug-binding pocket near the allosteric site that may be amenable to targeting with small molecules. Without antagonists, the apo dynamics reveal intermediate conformations along the activation pathway that provide insight into the basal dynamics of CCR2 and may also be useful for future drug design.
Learn More >Some variables have been proposed as predictors of efficacy of OnabotulinumtoxinA in chronic migraine patients, but data available are inconclusive. We aimed to analyse the influence of single nucleotide polymorphisms in the response to OnabotulinumtoxinA.
Learn More >Drug discovery research on new pain targets with human genetic validation, including the voltage-gated sodium channel NaV1.7, is being pursued to address the unmet medical need for chronic pain and the rising opioid epidemic. As part of early research efforts on this front, we have previously developed NaV1.7 inhibitory peptide-antibody conjugates with tarantula venom-derived GpTx-1 toxin peptides with extended half-life (80 h) in rodents but only moderate in vitro activity (hNaV1.7 IC50 = 250 nM) and without in vivo activity. We identified the more potent peptide JzTx-V from our natural peptide collection and improved its selectivity against other sodium channel isoforms through positional analoging. Here we report utilization of the JzTx-V scaffold in a peptide-antibody conjugate and architectural variations in linker, peptide loading, and antibody attachment site. We found conjugates with 100x improved in vitro potency relative to complementary GpTx-1 analogs, but pharmacokinetic and bioimaging analyses of these JzTx-V conjugates revealed a shorter than expected plasma half-life in vivo with accumulation in the liver. In an attempt to increase circulatory serum levels, we sought the reduction of the net +6 charge of the JzTx-V scaffold whilst retaining a desirable NaV in vitro activity profile. The conjugate of a JzTx-V peptide analog with a +2 formal charge maintained NaV1.7 potency with 18-fold improved plasma exposure in rodents. Balancing the loss in peptide and conjugate potency associated with the reduction of net charge necessary for improved target exposure resulted in a compound with moderate activity in a NaV1.7-dependent pharmacodynamic model but requires further optimization to identify a conjugate that can fully engage NaV1.7 in vivo.
Learn More >Neuropathy is a dose-limiting side effect of many chemotherapeutics, including bortezomib. The mechanisms underlying this condition are not fully elucidated even if a contribution of neuroinflammation was suggested. Here, we investigated the role of a chemokine family, the prokineticins (PKs), in the development of bortezomib-induced peripheral neuropathy (BIPN), and we used a PK receptor antagonist to counteract the development and progression of the pathology.
Learn More >In the past decade, migraine research has identified novel drug targets. In this review, we discuss recent data on emerging anti-migraine therapies.
Learn More >Bidirectional selection of mice for high (HA) and low (LA) swim stress-induced analgesia (SSIA) is associated with a divergent response to opioids. In the current study, we investigated whether the genetic divergence in opioid system activity between HA and LA mice also affects cannabinoid sensitivity. Additionally, we also investigated whether the endocannabinoid system mediates SSIA in these lines. Numerous reports support the existence of pharmacological and molecular interactions between the opioid and cannabinoid systems along the pain pathways, as both systems utilize the same G-protein subtype for signal transduction. Mice from both lines were treated with a non-selective CB/CB agonist, WIN55,212-2 and their behavior was evaluated according to the tetrad paradigm assessing antinociception, catalepsy, hypothermia and locomotor activity. Surprisingly, the engagement of CB receptors in SSIA was not confirmed. G-protein activation was studied in different brain regions and the spinal cord in the [S]GTPγS assay. It was shown that WIN55,212-2 produced more potent antinociception in HA than in LA mice. Also, HA mice displayed stronger cannabinoid-induced catalepsy in the bar test. However, LA mice were more sensitive to the hypothermic effect of WIN55,212-2. The intensity of behavioral responses to WIN55,212-2 was correlated with increased G-protein activation in the periaqueductal gray matter, frontal cortex, striatum and thalamus in HA mice. A weak response to WIN55,212-2 in LA mice could depend on impaired CB receptor signaling. In conclusion, differences in both opioid and cannabinoid sensitivity between HA and LA mice could stem from alterations in intracellular second messenger mechanisms involving G-protein activation.
Learn More >Opioids are a mainstay of acute pain management but can have many adverse effects, contributing to problematic long-term use. Opioid tolerance (increased dose needed for analgesia) and opioid-induced hyperalgesia (paradoxical increase in pain with opioid administration) can contribute to both poorly controlled pain and dose escalation. Hyperalgesia is particularly problematic as further opioid prescribing is largely futile. The mechanisms of opioid tolerance and hyperalgesia are complex, involving μ opioid receptor signalling pathways that offer opportunities for novel analgesic alternatives. The intracellular scaffold protein β-arrestin-2 is implicated in tolerance, hyperalgesia, and other opioid side-effects. Development of agonists biased against recruitment of β-arrestin-2 could provide analgesic efficacy with fewer side-effects. Alternative approaches include inhibition of peripheral μ opioid receptors and blockade of downstream signalling mechanisms, such as the non-receptor tyrosine kinase Src or N-methyl-D-aspartate receptors. Furthermore, it is prudent to use multimodal analgesic regimens to reduce reliance on opioids during the perioperative period. In the third paper in this Series we focus on clinical and mechanism-based understanding of tolerance and opioid-induced hyperalgesia, and discuss current and future strategies for pain management.
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