Brain pharmacology of intrathecal antisense oligonucleotides revealed through multimodal imaging.

Intrathecal (IT) delivery and pharmacology of antisense oligonucleotides (ASOs) for the CNS have been successfully developed to treat spinal muscular atrophy. However, ASO pharmacokinetic (PK) and pharmacodynamic (PD) properties remain poorly understood in the IT compartment. We applied multimodal imaging techniques to elucidate the IT PK and PD of unlabeled, radioactively labeled, or fluorescently labeled ASOs targeting ubiquitously expressed or neuron-specific RNAs. Following lumbar IT bolus injection in rats, all ASOs spread rostrally along the neuraxis, adhered to meninges, and were partially cleared to peripheral lymph nodes and kidneys. Rapid association with the pia and arterial walls preceded passage of ASOs across the glia limitans, along arterial intramural basement membranes, and along white-matter axonal bundles. Several neuronal and glial cell types accumulated ASOs over time, with evidence of probable glial accumulation preceding neuronal uptake. IT doses of anti-GluR1 and anti-Gabra1 ASOs markedly reduced the mRNA and protein levels of their respective neurotransmitter receptor protein targets by 2 weeks and anti-Gabra1 ASOs also reduced binding of the GABAA receptor PET ligand 18F-flumazenil in the brain over 4 weeks. Our multimodal imaging approaches elucidate multiple transport routes underlying the CNS distribution, clearance, and efficacy of IT-dosed ASOs.

pH-Dependent 5-Aminosalicylates Releasing Preparations Do Not Affect Thiopurine Metabolism.

BACKGROUND/AIMS: Thiopurines are key drugs in maintenance therapy for treating inflammatory bowel disease (IBD). Time-dependent 5-aminosalicylates (5-ASA) releasing preparations (time-dependent 5-ASA) increase 6-thioguanine nucleotide (6-TGN), an active metabolite of thiopurines. However, the effects of pH-dependent 5-ASA releasing preparations (pH-dependent 5-ASA) on thiopurine metabolism were not reported. METHODS: We conducted a retrospective study of 134 IBD patients who received thiopurine treatment. The 6-methylmercaptopurine (6-MMP)/6-TGN values after taking the same dose of thiopurine preparations for at least 28 days were included. RESULTS: There was a significant decrease in the 6-MMP/6-TGN ratio in time-dependent 5-ASA compared with group without 5-ASA preparations and the pH-dependent 5-ASA group (p = 0.008 and < 0.001 respectively). Spearman's rank correlation coefficient indicated a negative relationship between the daily oral dose of time-dependent 5-ASA and the 6-MMP/6-TGN ratio (r = -0.362, p = 0.003). Multivariate logistic regression analysis was performed in the groups with 6-MMP/6-TGN ratios of 1 or more and less than 1. The use of time-dependent 5-ASA and concomitant allopurinol negatively affected the independent 6-MMP/6-TGN ratio (p = 0.006 and 0.007 respectively). CONCLUSION: Our study revealed that time-dependent but not pH-dependent 5-ASA decreases the 6-MMP/6-TGN ratio. We also confirmed that concomitant allopurinol results in a low 6-MMP/6TGN ratio.

Structural optimization and additional targets identification of antisense oligonucleotide G3139 encapsulated in a neutral cytidinyl-lipid combined with a cationic lipid in vitro and in vivo.

Antisense oligonucleotides (ASOs) usually contain a fully phosphorothioate (PS) backbone, which possibly interact with many genes and proteins under intracellular conditions. G3139 is an ASO that targets Bcl-2 mRNA and induces cell apoptosis. Here, we report a kind of cytidinyl-lipid combined with a cationic lipid (DNCA/CLD, molar ration, 28:3, named mix), which may interact with oligonucleotides via H-bond formation, pi-stacking and electrostatic interaction, accompanied by low zeta potentials. The IC50 value of G3139 delivered by mix-lipid reduced from above 20 µM to 0.158 µM for MCF-7/ADR, and exhibited stronger antiproliferation upon other cancer cell lines. In addition, PS modification in the 3'-half of G3139 (especially at positions 13-16) enhanced serum stability, target specificity and anticancer activity. Also, a locked nucleic acid (LNA) gapmer G3139 (LNA-G3139) showed superior antiproliferation (78.5%) and Bcl-2 mRNA suppression effects (85.5%) at 200 nM, mainly due to its high complementary RNA affinity. More apoptosis-associated targets were identified, and a lower level of non-specific protein binding (HSA) revealed that both antisense and aptamer mechanisms might simultaneously exist. A combination of a new delivery system and chemical modifications, such as in LNA-G3139, may have potential clinical application prospects in the future.

Fear memory consolidation in sleep requires protein kinase A.

It is well established that protein kinase A (PKA) is involved in hippocampal dependent memory consolidation. Sleep is also known to play an important role in this process. However, whether sleep-dependent memory consolidation involves PKA activation has not been clearly determined. Using behavioral observation, animals were categorized into sleep and awake groups. We show that intrahippocampal injections of the PKA inhibitor Rp-cAMPs in post-contextual fear conditioning sleep produced a suppression of long-term fear memory, while injections of Rp-cAMPs during an awake state, at a similar time point, had no effect. In contrast, injections of the PKA activator Sp-cAMPs in awake state, rescued sleep deprivation-induced memory impairments. These results suggest that following learning, PKA activation specifically in sleep is required for the consolidation of long-term memory.

Nitric oxide modulates ATP-evoked currents in mouse Leydig cells.

Testosterone synthesis within Leydig cells is a calcium-dependent process. Intracellular calcium levels are regulated by different processes including ATP-activated P2X purinergic receptors, T-type Ca2+ channels modulated by the luteinizing hormone, and intracellular calcium storages recruited by a calcium-induced calcium release mechanism. On the other hand, nitric oxide (NO) is reported to have an inhibitory role in testosterone production. Based on these observations, we investigated the interaction between the purinergic and nitrergic systems in Leydig cells of adult mice. For this purpose, we recorded ATP-evoked currents in isolated Leydig cells using the whole cell patch clamp technique after treatment with L-NAME (300 µM and 1 mM), L-arginine (10, 100, 300, and 500 µM), ODQ (300 µM), and 8-Br-cGMP (100 µM). Our results show that NO produced by Leydig cells in basal conditions is insufficient to change the ATP-evoked currents and that extra NO provided by adding 300 µM L-arginine positively modulates the current through a mechanism involving the NO/cGMP signaling pathway. Thus, we report an interaction between the nitrergic and purinergic systems in Leydig cells and suggest that Ca2+ entry via the purinergic receptors can be regulated by NO.

Optic nerve regeneration in the mouse is a complex trait modulated by genetic background.

Purpose: The present study is designed to identify the influences of genetic background on optic nerve regeneration using the two parental strains (C57BL/6J and DBA/2J) and seven BXD recombinant inbred mouse strains. Methods: To study regeneration in the optic nerve, Pten was knocked down in the retinal ganglion cells using adenoassociated virus (AAV) delivery of shRNA, and a mild inflammatory response was induced with an intravitreal injection of zymosan with CPT-cAMP. The axons of the retinal ganglion cells were damaged by optic nerve crush (ONC). Following a 12-day survival period, regenerating axons were labeled by cholera toxin B, and 2 days later, the regenerating axons within the optic nerve were examined. The number of axons at 0.5 mm and 1 mm from the crush site were counted. In addition, we measured the distance that five axons had grown down the nerve and the longest distance a single axon reached. Results: The analysis revealed a considerable amount of differential axonal regeneration across the seven BXD strains and the parental strains. There was a statistically significant difference (p=0.014 Mann-Whitney U test) in the regenerative capacity in the number of axons reaching 0.5 mm from a low of 236.1±24.4 axons in the BXD102 mice to a high of 759.8±79.2 axons in the BXD29 mice. There were also statistically significant differences (p=0.014 Mann-Whitney U test) in the distance axons traveled. Looking at a minimum of five axons, the shortest distance was 787.2±46.5 µm in the BXD102 mice, and the maximum distance was 2025.5±223.3 µm in the BXD29 mice. Conclusions: Differences in genetic background can have a profound effect on axonal regeneration causing a threefold increase in the number of regenerating axons at 0.5 mm from the crush site and a 2.5-fold increase in the distance traveled by at least five axons in the damaged optic nerve.

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of Gi-protein inhibitor.

BACKGROUND: Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as inflammatory cytokines and chemokines. The involvement of Gi protein in mediating LPS effects has been demonstrated in murine macrophages and various cell types of human origin. PURPOSE: The aim of the present work was to evaluate the potential of a Gi-protein inhibitor encapsulated in liposomes in reducing the inflammatory effects induced by LPS in monocytes/macrophages. MATERIALS AND METHODS: Guanosine 5'-O-(2-thiodiphosphate) (GOT), a guanosine diphosphate analog that completely inhibits G-protein activation by guanosine triphosphate and its analogs, was encapsulated into liposomes and tested for anti-inflammatory effects in LPS-activated THP1 monocytes or THP1-derived macrophages. The viability of monocytes/macrophages after incubation with different concentrations of free GOT or liposome-encapsulated GOT was assessed by MTT assay. MAPK activation and production of IL1ß, TNFα, IL6, and MCP1 were assessed in LPS-activated monocytes/macrophages in the presence or absence of free or encapsulated GOT. In addition, the effect of free or liposome-encapsulated GOT on LPS-stimulated monocyte adhesion to activated endothelium and on monocyte chemotaxis was evaluated. RESULTS: We report here that GOT-loaded liposomes inhibited activation of MAPK and blocked the production of the cytokines IL1ß, TNFα, IL6, and MCP1 induced by LPS in monocytes and macrophages. Moreover, GOT encapsulated in liposomes reduced monocyte adhesion and chemotaxis. All demonstrated events were in contrast with free GOT, which showed reduced or no effect on monocyte/macrophage activation with LPS. CONCLUSION: This study demonstrates the potential of liposomal GOT in blocking LPS proinflammatory effects in monocytes/macrophages.

Nitric oxide modulates ATP-evoked currents in mouse Leydig cells

Testosterone synthesis within Leydig cells is a calcium-dependent process. Intracellular calcium levels are regulated by different processes including ATP-activated P2X purinergic receptors, T-type Ca2+ channels modulated by the luteinizing hormone, and intracellular calcium storages recruited by a calcium-induced calcium release mechanism. On the other hand, nitric oxide (NO) is reported to have an inhibitory role in testosterone production. Based on these observations, we investigated the interaction between the purinergic and nitrergic systems in Leydig cells of adult mice. For this purpose, we recorded ATP-evoked currents in isolated Leydig cells using the whole cell patch clamp technique after treatment with L-NAME (300 μM and 1 mM), L-arginine (10, 100, 300, and 500 μM), ODQ (300 μM), and 8-Br-cGMP (100 μM). Our results show that NO produced by Leydig cells in basal conditions is insufficient to change the ATP-evoked currents and that extra NO provided by adding 300 μM L-arginine positively modulates the current through a mechanism involving the NO/cGMP signaling pathway. Thus, we report an interaction between the nitrergic and purinergic systems in Leydig cells and suggest that Ca2+ entry via the purinergic receptors can be regulated by NO.

Nusinersen: antisense oligonucleotide to increase SMN protein production in spinal muscular atrophy.

Patients with spinal muscular atrophy (SMA) have an autosomal recessive disease that limits their ability to produce survival motor neuron (SMN) protein in the CNS resulting in progressive wasting of voluntary muscles. Detailed studies over several years have demonstrated that phosphorothioate and 2'-O-methoxyethyl- modified antisense oligonucleotides (ASOs) targeting the ISS-N1 site increase SMN2 exon 7 inclusion, thus increasing levels of SMN protein in a dose- and time-dependent manner in liver, kidney and skeletal muscle, and CNS tissues only when administered intrathecally. On a dose basis, nusinersen was found to be the most potent ASO for SMN2 splicing correction in the CNS of adult mice. After nusinersen was found to increase levels of SMN protein in the CNS of mice and subhuman primates without causing significant adverse events, it was advanced into clinical studies in patients with SMA. These trials in SMA patients have demonstrated significant improvements in various measures of motor function and in progression to movement developments not normally seen in SMA patients. In addition, there have been significant extensions in life expectancy. These findings led to the U.S. and European approval of nusinersen for use in SMA patients of all ages.

Tat-Tagged and Folate-Modified N-Succinyl-chitosan (Tat-Suc-FA) Self-assembly Nanoparticle for Therapeutic Delivery OGX-011 to A549 Cells.

The objective of this study was to develop a novel type of an antisense oligonucleotide (OGX-011) loaded Tat-tagged and folate-modified N-succinyl-chitosan (Tat-Suc-FA) nanoparticles (NPs) for improving tumor targetability. In this study, Tat-Suc-FA/OGX-011NPs were prepared and its physicochemical characterizations were also evaluated. The nanoparticles showed an average diameter of 73 ± 16.6 nm, the zeta potential of +23.6 ± 0.3 mV, and a high entrapment efficiency of 89.6 ± 6.6%. Transmission electron microscopy analysis showed the nanoparticles were mostly spherical and well dispersed. The delivery efficiency of this system was investigated both in vitro and in vivo. In comparison with nontargeted Lipofectamin2000/OGX-011 and free OGX-011, Tat-Suc-FA/GOX-011 showed the highest apoptosis rate of 14.2% ± 1.8% and significant uptake in A549 cells. Tat-Suc-FA NPs loaded with GOX-011 induced significant down-regulation of s-CLU mRNA and protein levels in A549 cells. In A549 tumor-bearing mice model, Tat-Suc-FA/GOX-011 produced a more efficient down-regulation of s-CLU compared to Lipofectamin2000/OGX-011. Furthermore, the combined use of Tat-Suc-FA/OGX-011 with DDP chemotherapy showed a most significant inhibition of tumor growth and greatly enhanced the survival rate of A549 tumor-bearing mice. These findings suggested successful application of Tat-Suc-FA NPs for the high efficiency and specificity in therapeutic delivery of OGX-011 to A549 cells.

A population pharmacokinetic meta-analysis of custirsen, an antisense oligonucleotide, in oncology patients and healthy subjects.

AIMS: Custirsen (OGX-011/TV-1011), a second-generation antisense oligonucleotide that reduces clusterin production, is under investigation with chemotherapy in prostate and lung cancer. This meta-analysis evaluated the population pharmacokinetics (PK) of custirsen in cancer patients and healthy subjects. METHODS: The population PK analysis used custirsen plasma concentrations from five Phase 1 studies, one Phase 1/2 study, and one Phase 3 study in two stages. Cancer patients received multiple doses of custirsen (40-640 mg intravenously over 120 min) with chemotherapy; healthy subjects received single or multiple doses (320-640 mg). An interim population PK model was developed using a nonlinear mixed-effect approach incorporating data from four Phase 1 or 1/2 studies, followed by model refinement and inclusion of two Phase 1 and one Phase 3 studies. RESULTS: The final model was developed with 5588 concentrations from 631 subjects with doses of 160-640 mg. Custirsen PK was adequately described by a three-compartment model with first-order elimination. For a representative 66-year-old individual with body weight 82 kg and serum creatinine level 0.933 mg dl-1 , the estimated typical (95% CI) parameter values were clearance (CL) = 2.36 (2.30-2.42) l h-1 , central volume of distribution (V1 ) = 6.08 (5.93-6.23) l, peripheral volume of distribution (V2 ) = 1.13 (1.01-1.25) l, volume of the second peripheral compartment (V3 ) = 15.8 (14.6-17.0) l, inter-compartmental clearance Q2 = 0.0755 (0.0689-0.0821) l h-1 , and Q3 = 0.0573 (0.0532-0.0614) l h-1 . Age, weight and serum creatinine were predictors of CL; age was a predictor of Q3 . CONCLUSION: A population PK model for custirsen was successfully developed in cancer patients and healthy subjects, including covariates contributing to variability in custirsen PK.

Custirsen in combination with docetaxel and prednisone for patients with metastatic castration-resistant prostate cancer (SYNERGY trial): a phase 3, multicentre, open-label, randomised trial.

BACKGROUND: Clusterin is a chaperone protein associated with treatment resistance and upregulated by apoptotic stressors such as chemotherapy. Custirsen is a second-generation antisense oligonucleotide that inhibits clusterin production. The aim of the SYNERGY trial was to investigate the effect of custirsen in combination with docetaxel and prednisone on overall survival in patients with metastatic castration-resistant prostate cancer. METHODS: SYNERGY was a phase 3, multicentre, open-label, randomised trial set at 134 study centres in 12 countries. Patients were eligible for participation if they had: metastatic castration-resistant prostate cancer and had received no previous chemotherapy; prostate-specific antigen greater than 5 ng/mL; and a Karnofsky performance score of 70% or higher. Patients were randomly assigned 1:1 centrally to either the docetaxel, prednisone, and custirsen combination or docetaxel and prednisone alone. Patients were not masked to treatment allocation. Randomisation was stratified by opioid use for cancer-related pain and radiographic evidence of progression. All patients received docetaxel 75 mg/m2 intravenously with 5 mg of prednisone orally twice daily. Patients assigned docetaxel, prednisone, and custirsen received weekly doses of custirsen 640 mg intravenously after three loading doses of 640 mg. The primary endpoint was overall survival analysed in the intention-to-treat population. Patients who received at least one study dose were included in the safety analysis set. This trial is registered with ClinicalTrials.gov, number NCT01188187. The trial is completed and final analyses are reported here. FINDINGS: Between Dec 10, 2010, and Nov 7, 2012, 1022 patients were enrolled to the trial, of whom 510 were assigned docetaxel, prednisone, and custirsen and 512 were allocated docetaxel and prednisone. No difference in overall survival was recorded between the two groups (median survival 23·4 months [95% CI 20·9-24·8] with docetaxel, prednisone, and custirsen vs 22·0 months [19·5-24·0] with docetaxel and prednisone; hazard ratio [HR] 0·93, 95% CI 0·79-1·10; p=0·415). The most common adverse events of grade 3 or worse in the docetaxel, prednisone and custirsen group (n=501) compared with the docetaxel and prednisone alone group (n=499) were neutropenia (grade 3, 63 [13%] vs 28 [6%]; grade 4, 98 [20%] vs 77 [15%]), febrile neutropenia (grade 3, 52 [10%] vs 31 [6%]; grade 4, four [1%] vs two [<1%]), and fatigue (grade 3, 53 [11%] vs 41 [8%]; grade 4, three [1%] vs one [<1%]). One or more serious adverse events were reported for 214 (43%) of 501 patients treated with docetaxel, prednisone, and custirsen and 181 (36%) of 499 receiving docetaxel and prednisone alone. Adverse events were attributable to 23 (5%) deaths in the docetaxel, prednisone, and custirsen group and 24 (5%) deaths in the docetaxel and prednisone alone group. INTERPRETATION: Addition of custirsen to first-line docetaxel and prednisone was reasonably well tolerated, but overall survival was not significantly longer for patients with metastatic castration-resistant prostate cancer treated with this combination, compared with patients treated with docetaxel and prednisone alone. FUNDING: OncoGenex Technologies.

The Effects of 2'-O-Methoxyethyl Containing Antisense Oligonucleotides on Platelets in Human Clinical Trials.

A thorough analysis of clinical trial data in the Ionis integrated safety database (ISDB) was performed to determine if there is a class effect on platelet numbers and function in subjects treated with 2'-O-methoxyethyl (2'MOE)-modified antisense oligonucleotides (ASOs). The Ionis ISDB includes over 2,600 human subjects treated with 16 different 2'MOE ASOs in placebo-controlled and open-label clinical trials over a range of doses up to 624 mg/week and treatment durations as long as 4.6 years. This analysis showed that there is no class generic effect on platelet numbers and no incidence of confirmed platelet levels below 50 K/µL in subjects treated with 2'MOE ASOs. Only 7 of 2,638 (0.3%) subjects treated with a 2'MOE ASO experienced a confirmed postbaseline (BSLN) platelet count between 100 and 50 K/µL. Three of sixteen 2'MOE ASOs had >10% incidence of platelet decreases >30% from BSLN, suggesting that certain sequences may associate with clinically insignificant platelet declines. Further to these results, we found no evidence that 2'MOE ASOs alter platelet function, as measured by the lack of clinically relevant bleeding in the presence or absence of other drugs that alter platelet function and/or number and by the results from trials conducted with the factor XI (FXI) ASO.

Lipid Nanoparticles Loaded with an Antisense Oligonucleotide Gapmer Against Bcl-2 for Treatment of Lung Cancer.

PURPOSE: Bcl-2 is an anti-apoptotic gene that is frequently overexpressed in human cancers. G3139 is an antisense oligonucleotide against bcl-2 that has shown limited efficacy in clinical trials. Here, we report the synthesis of a new antisense oligonucleotide containing additional chemical modifications and its delivery using nanoparticles. METHODS: An oligonucleotide G3139-GAP was synthesized, which has 2'-O-methyl nucleotides at the 5' and 3' ends based on a "gapmer" design. Furthermore, G3139-GAP was incorporated into lipid nanoparticles (LNPs) composed of DOTAP/egg PC/cholesterol/Tween 80. The LNP-loaded G3139-GAP was evaluated in A549 lung cancer cells both in vitro and in a murine xenograft model for biological activity and therapeutic efficacy. RESULTS: The LNPs showed excellent colloidal and serum stability, and high encapsulation efficiency for G3139-GAP. They have a mean particle diameter and zeta potential of 134 nm and 9.59 mV, respectively. G3139-GAP-LNPs efficiently downregulated bcl-2 expression in A549 cells, as shown by 40% and 83% reduction in mRNA and protein levels, respectively. Furthermore, G3139-GAP-LNPs were shown to inhibit tumor growth, prolong survival, and downregulate tumor bcl-2 expression in an A549 murine xenograft tumor model. These data indicate that G3139-GAP-LNPs have excellent anti-tumor efficacy and warrant further evaluation.

Lipid-modified oligonucleotide conjugates: Insights into gene silencing, interaction with model membranes and cellular uptake mechanisms.

The ability of oligonucleotides to silence specific genes or inhibit the biological activity of specific proteins has generated great interest in their use as research tools and therapeutic agents. Unfortunately, their biological applications meet the limitation of their poor cellular accessibility. Developing an appropriate delivery system for oligonucleotides is essential to achieve their efficient cellular uptake. In the present work a series of phosphorothioate lipid-oligonucleotide hybrids were synthesized introducing covalently single or double lipid tails at both 3'- and 5'-termini of an antisense oligonucleotide. Gene transfections in cultured cells showed antisense luciferase inhibition without the use of a transfecting agent for conjugates modified with the double-lipid tail at 5'-termini. The effect of the double lipid-tailed modification was further studied in detail in several model membrane systems as well as in cellular uptake experiments. During these studies the spontaneous formation of self-assembled microstructures is clearly observed. Lipidation allowed the efficient incorporation of the oligonucleotide in HeLa cells by a macropinocytosis mechanism without causing cytotoxicity in cells or altering the binding properties of the oligonucleotide conjugates. In addition, both single- and double-tailed compounds showed a similar behavior in lipid model membranes, making them useful in nucleotide-based technologies.

Thiolated alginate-based multiple layer mucoadhesive films of metformin forintra-pocket local delivery: in vitro characterization and clinical assessment.

INTRODUCTION: Periodontal disease broadly defines group of conditions in which the supportive structure of the tooth (periodontium) is destroyed. Recent studies suggested that the anti-diabetic drug metformin hydrochloride (MF) has an osteogenic effect and is beneficial for the management of periodontitis. OBJECTIVE: Development of strong mucoadhesive multiple layer film loading small dose of MF for intra-pocket application. METHODOLOGY: Multiple layer film was developed by double casting followed by compression method. Either 6% carboxy methyl cellulose sodium (CMC) or sodium alginate (ALG) constituted the inner drug (0.6%) loaded layer. Thiolated sodium alginate (TSA; 2 or 4%) constituted the outer drug free layers to enhance mucoadhesion and achieve controlled drug release. Optimized formulation was assessed clinically on 20 subjects. RESULTS: Films were uniform, thin and hard enough for easy insertion into periodontal pockets. Based on water uptake and in vitro drug release, CMC based film with 4% TSA as an outer layer was the optimized formulation with enhanced mucoadhesion and controlled drug release (83.73% over 12 h). SEM showed the effective fabrication of the triple layer film in which connective lines between the layers could be observed. FTIR examination suggests possibility of hydrogen bonding between the -NH groups of metformin and -OH groups of CMC. DSC revealed the presence of MF mainly in the amorphous form. Clinical results indicated improvement of all clinical parameters six months post treatment. CONCLUSION: The results suggested that local application of the mucoadhesive multiple layer films loaded with metformin hydrochloride was able to manage moderate chronic periodontitis.

Integrated Safety Assessment of 2'-O-Methoxyethyl Chimeric Antisense Oligonucleotides in NonHuman Primates and Healthy Human Volunteers.

The common chemical and biological properties of antisense oligonucleotides provide the opportunity to identify and characterize chemical class effects across species. The chemical class that has proven to be the most versatile and best characterized is the 2'-O-methoxyethyl chimeric antisense oligonucleotides. In this report we present an integrated safety assessment of data obtained from controlled dose-ranging studies in nonhuman primates (macaques) and healthy human volunteers for 12 unique 2'-O-methoxyethyl chimeric antisense oligonucleotides. Safety was assessed by the incidence of safety signals in standardized laboratory tests for kidney and liver function, hematology, and complement activation; as well as by the mean test results as a function of dose level over time. At high doses a number of toxicities were observed in nonhuman primates. However, no class safety effects were identified in healthy human volunteers from this integrated data analysis. Effects on complement in nonhuman primates were not observed in humans. Nonhuman primates predicted safe doses in humans, but over predicted risk of complement activation and effects on platelets. Although limited to a single chemical class, comparisons from this analysis are considered valid and accurate based on the carefully controlled setting for the specified study populations and within the total exposures studied.

P2Y13 receptors mediate presynaptic inhibition of acetylcholine release induced by adenine nucleotides at the mouse neuromuscular junction.

It is known that adenosine 5'-triphosphate (ATP) is released along with the neurotransmitter acetylcholine (ACh) from motor nerve terminals. At mammalian neuromuscular junctions (NMJs), we have previously demonstrated that ATP is able to decrease ACh secretion by activation of P2Y receptors coupled to pertussis toxin-sensitive Gi/o protein. In this group, the receptor subtypes activated by adenine nucleotides are P2Y12 and P2Y13. Here, we investigated, by means of pharmacological and immunohistochemical assays, the P2Y receptor subtype that mediates the modulation of spontaneous and evoked ACh release in mouse phrenic nerve-diaphragm preparations. First, we confirmed that the preferential agonist for P2Y12-13 receptors, 2-methylthioadenosine 5'-diphosphate trisodium salt hydrate (2-MeSADP), reduced MEPP frequency without affecting MEPP amplitude as well as the amplitude and quantal content of end-plate potentials (EPPs). The effect on spontaneous secretion disappeared after the application of the selective P2Y12-13 antagonists AR-C69931MX or 2-methylthioadenosine 5'-monophosphate triethylammonium salt hydrate (2-MeSAMP). 2-MeSADP was more potent than ADP and ATP in reducing MEPP frequency. Then we demonstrated that the selective P2Y13 antagonist MRS-2211 completely prevented the inhibitory effect of 2-MeSADP on MEPP frequency and EPP amplitude, whereas the P2Y12 antagonist MRS-2395 failed to do this. The preferential agonist for P2Y13 receptors inosine 5'-diphosphate sodium salt (IDP) reduced spontaneous and evoked ACh secretion and MRS-2211 abolished IDP-mediated modulation. Immunohistochemical studies confirmed the presence of P2Y13 but not P2Y12 receptors at the end-plate region. Disappearance of P2Y13 receptors after denervation suggests the presynaptic localization of the receptors. We conclude that, at motor nerve terminals, the Gi/o protein-coupled P2Y receptors implicated in presynaptic inhibition of spontaneous and evoked ACh release are of the subtype P2Y13. This study provides new insights into the types of purinergic receptors that contribute to the fine-tuning of cholinergic transmission at mammalian neuromuscular junction.