Disentangling the enigmatic role of ephrin signaling in chronic pain: Moving towards future anti-pain therapeutics.

Chronic pain is a common and debilitating condition with a huge social and economic burden worldwide. Currently, available drugs in clinics are not adequately effective and possess a variety of severe side effects leading to treatment withdrawal and poor quality of life. The ongoing search for new therapeutics with minimal side effects for chronic pain management remains a high research priority. Erythropoietin-producing human hepatocellular carcinoma cell receptor (Eph) is a tyrosine kinase receptor that is involved in neurodegenerative disorders, including pain. The Eph receptor interacts with several molecular switches, such as N methyl d-aspartate receptor (NMDAR), mitogen-activated protein kinase (MAPK), calpain 1, caspase 3, protein kinase a (PKA), and protein kinase Cy (PKCy), which in turn regulates pathophysiology of chronic pain. Here we highlight the emerging evidence of the Ephs/ephrin system as a possible near-future therapeutic target for the treatment of chronic pain and discuss the various mechanism of its involvement. We critically analyse the present status of Eph receptor system and conclude that extrapolating the pharmacological and genetic approaches using a strong therapeutic development framework could serve as next-generation analgesics for the management of chronic pain.

Modulation of KIF17/NR2B crosstalk by tozasertib attenuates inflammatory pain in rats.

Chronic pain is among the most burdensome and devastating disorders affecting millions of people worldwide. Recent studies suggest the role of kinesin nanomotors in development and maintenance of chronic pain. KIF17 is a member of kinesin superfamily that binds to NR2B cargo system via mLin10 scaffolding protein and makes the NMDARs functional at cell surface. NMDA receptor activation is known to induce the central sensitization and excitotoxicity which can be recognized by the glial cells followed by the release of cytokine storm at spinal and supraspinal level leading to chronic pain. In this study, we have investigated the role of aurora kinase in the regulation of KIF17 and NR2B trafficking in the animal model of chronic inflammatory pain. Tozasertib (10, 20, and 40 mg/kg i.p.), a pan aurora kinase inhibitor, significantly attenuates acute inflammatory pain and suppresses enhanced pain hypersensitivity to heat, cold, and mechanical stimuli in CFA-injected rats. Molecular investigations suggest enhanced expression of KIF17/mLin10/NR2B in L4-L5 dorsal root ganglion (DRG) and spinal cord of CFA-injected rats which was significantly attenuated on treatment with tozasertib. Moreover, tozasertib treatment significantly attenuated CFA-induced oxido-nitrosative stress and macrophage activation in DRG and microglia activation in spinal cord of rats. Findings from the current study suggest that tozasertib mediates anti-nociceptive activity by inhibiting aurora kinase-mediated KIF17/mLin10/NR2B signaling.

Multifarious Targets and Recent Developments in the Therapeutics for the Management of Bone Cancer Pain.

Bone cancer pain (BCP) is a distinct pain state showing characteristics of both neuropathic and inflammatory pain. On average, almost 46% of cancer patients exhibit BCP with numbers flaring up to as high as 76% for terminally ill patients. Patients suffering from BCP experience a compromised quality of life, and the unavailability of effective therapeutics makes this a more devastating condition. In every individual cancer patient, the pain is driven by different mechanisms at different sites. The mechanisms behind the manifestation of BCP are very complex and poorly understood, which creates a substantial barrier to drug development. Nevertheless, some of the key mechanisms involved have been identified and are being explored further to develop targeted molecules. Developing a multitarget approach might be beneficial in this case as the underlying mechanism is not fixed and usually a number of these pathways are simultaneously dysregulated. In this review, we have discussed the role of recently identified novel modulators and mechanisms involved in the development of BCP. They include ion channels and receptors involved in sensing alteration of temperature and acidic microenvironment, immune system activation, sodium channels, endothelins, protease-activated receptors, neurotrophins, motor proteins mediated trafficking of glutamate receptor, and some bone-specific mechanisms. Apart from this, we have also discussed some of the novel approaches under preclinical and clinical development for the treatment of bone cancer pain.

Kinesin Nanomotors Mediated Trafficking of NMDA-Loaded Cargo as A Novel Target in Chronic Pain.

Chronic pain is among the most prevalent burdensome disorders worldwide. The N-methyl-d-aspartate (NMDA) receptor system plays a critical role in central sensitization, a primary feature of chronic pain. Despite the proven efficacy of exogenous ligands to this receptor system in preclinical studies, evidence for the clinical efficacy of NMDA antagonists for the treatment of chronic pain is weak. Researchers are studying alternate approaches, rather than direct inhibition of the NMDA receptors in pain processing neurons. This indirect approach utilizes the modulation of molecular switches that regulates the synthesis, maturation, and transport of receptors from cellular organelles to the synaptic membrane. Kinesins are nanomotors that anterogradely transport the cargo using microtubule tracks across the neurons. Various members of the kinesin family, including KIF17, KIF11, KIF5b, and KIF21a, regulate the intracellular transport of NMDA receptors. Pharmacological targeting of these ATP-driven nanomotors could be a useful tool for manipulating the NMDAR functioning. It could provide the potential for the development of a novel strategy for the management of chronic pain.

Efficacy and safety of a nano-emulsion gel formulation of adapalene 0.1% and clindamycin 1% combination in acne vulgaris: a randomized, open label, active-controlled, multicentric, phase IV clinical trial.

BACKGROUND: Acne vulgaris is a very common skin disease with a significant detrimental effect on the quality of life of the patients. AIMS: To assess the comparative efficacy and safety of a nano-emulsion gel formulation of adapalene and clindamycin combination with its conventional formulation in the treatment of acne vulgaris of the face. It was a prospective, randomized, open label, active-controlled, multicentric, clinical trial. METHODS: Eligible patients suffering from acne vulgaris of the face were randomized to receive once-daily treatment with a nano-emulsion gel or conventional gel formulation of adapalene 0.1% and clindamycin (as phosphate) 1% combination for 12 weeks. Total, inflammatory and noninflammatory lesion counts, with grading of acne severity were carried out on a monthly basis. Safety assessments were done to determine the comparative local and systemic tolerability. Two-tailed significance testing was carried out with appropriate statistical tests, and P-values < 0.05 were considered as significant. RESULTS: 209/212 patients enrolled in the study were eligible for efficacy and safety assessments in both nano-emulsion gel (118/119 patients) and conventional gel (91/93 patients) groups. Significantly better reductions in total (79.7% vs. 62.7%), inflammatory (88.7% vs. 71.4%) and noninflammatory (74.9% vs. 58.4%) lesions were reported with the nano-emulsion gel as compared to the conventional gel (P < 0.001 for all). Mean acne severity score also reduced significantly more with the nano-emulsion formulation (1.9 ± 0.9 vs. 1.4 ± 1.0; P < 0.001) than the comparator. Significantly lower incidence and lesser intensity of adverse events like local irritation (4.2% vs. 19.8%; P < 0.05) and erythema (0.8% vs. 9.9%; P < 0.05) were recorded with the nano-emulsion gel. CONCLUSIONS: The nano-emulsion gel formulation of adapalene and clindamycin combination appears to be more efficacious and better tolerated than the conventional formulation for the treatment of acne vulgaris in Indian patients. Further studies can elucidate the comparative treatment benefits of this nano-emulsion gel formulation.