ns-9283 and Disease-Models--Animal

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Nicotinic acetylcholine receptors (nAChRs) function as ligand-gated ion channels activated by the neurotransmitter acetylcholine. Gene knockout and antisense studies coupled with pharmacological studies with nAChR agonists have documented a role of α4β2 nAChR activation in analgesia. ABT-594, for the first time, provided clinical validation to the nAChR agonist pharmacology as a novel mechanism for treatment of pain. However, ABT-594 was poorly tolerated at the efficacious doses, particularly with respect to the side effects of nausea and emesis, which is thought to be mediated by activation of the ganglionic-type (α3-containing) nAChRs. An alternate approach is to selectively modulate the α4β2 nAChR via positive allosteric modulation. Positive allosteric modulators (PAMs) are compounds that do not interact with the agonist binding sites or possess intrinsic activity at the receptor per se, but potentiate the effects of the agonist. NS9283 (also known as A-969933), the first oxadiazole analog, was found to selectively enhance the potency of a range of nAChR agonists at α4β2, but not α3β4, nAChRs. Studies reported here, along with the accompanying manuscript [1] collectively point to the conclusion, based on preclinical models, that the analgesic efficacy of clinically well-tolerated doses of ABT-594 in humans can be significantly enhanced by co-administration with the α4β2 PAM. Additionally, studies in ferrets demonstrate no exaggeration of emetic effect when ABT-594 is co-dosed with NS9283. Cardiovascular studies in anesthetized dogs achieve supra-therapeutic plasma concentrations of ABT-594 (>20-fold) without hemodynamic or electrophysiological effects using the co-administration paradigm.

Topics: Allosteric Regulation; Allosteric Site; Analgesics; Animals; Azetidines; Calcium; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Ferrets; HEK293 Cells; Hemodynamics; Humans; Low Back Pain; Male; Molecular Structure; Nicotinic Agonists; Pyridines; Rats; Rats, Sprague-Dawley; Receptors, Nicotinic; Transfection; Vomiting

Positive modulation of the neuronal nicotinic acetylcholine receptor (nAChR) α4β2 subtype by selective positive allosteric modulator NS-9283 has shown to potentiate the nAChR agonist ABT-594-induced anti-allodynic activity in preclinical neuropathic pain. To determine whether this benefit can be extended beyond neuropathic pain, the present study examined the analgesic activity and adverse effect profile of co-administered NS-9283 and ABT-594 in a variety of preclinical models in rats. The effect of the combined therapy on drug-induced brain activities was also determined using pharmacological magnetic resonance imaging. In carrageenan-induced thermal hyperalgesia, co-administration of NS-9283 (3.5 μmol/kg, i.p.) induced a 6-fold leftward shift of the dose-response of ABT-594 (ED(50)=26 vs. 160 nmol/kg, i.p.). In the paw skin incision model of post-operative pain, co-administration of NS-9283 similarly induced a 6-fold leftward shift of ABT-594 (ED(50)=26 vs. 153 nmol/kg). In monoiodo-acetate induced knee joint pain, co-administration of NS-9283 enhanced the potency of ABT-594 by 5-fold (ED(50)=1.0 vs. 4.6 nmol/kg). In pharmacological MRI, co-administration of NS-9283 was shown to lead to a leftward shift of ABT-594 dose-response for cortical activation. ABT-594 induced CNS-related adverse effects were not exacerbated in presence of an efficacious dose of NS-9283 (3.5 μmol/kg). Acute challenge of NS-9283 produced no cross sensitization in nicotine-conditioned animals. These results demonstrate that selective positive allosteric modulation at the α4β2 nAChR potentiates nAChR agonist-induced analgesic activity across neuropathic and nociceptive preclinical pain models without potentiating ABT-594-mediated adverse effects, suggesting that selective positive modulation of α4β2 nAChR by PAM may represent a novel analgesic approach.

Topics: Allosteric Regulation; Analgesics; Animals; Azetidines; Behavior, Animal; Body Temperature; Brain; Disease Models, Animal; Drug Therapy, Combination; Magnetic Resonance Imaging; Male; Nicotinic Agonists; Osteoarthritis; Oxadiazoles; Pain; Pyridines; Rats; Rats, Sprague-Dawley; Receptors, Nicotinic