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Monoamine oxidase-B (MAO-B) is a well-established therapeutic target for Parkinson’s disease (PD); however, previous clinical studies on currently available irreversible MAO-B inhibitors have yielded disappointing neuroprotective effects. Here, we tested the therapeutic potential of KDS2010, a recently synthesized potent, selective, and reversible MAO-B inhibitor in multiple animal models of PD. We designed and synthesized a series of α-aminoamide derivatives and found that derivative KDS2010 exhibited the highest potency, specificity, reversibility, and bioavailability (> 100%). In addition, KDS2010 demonstrated significant neuroprotective and anti-neuroinflammatory efficacy against nigrostriatal pathway destruction in the mouse MPTP model of parkinsonism. Treatment with KDS2010 also alleviated parkinsonian motor dysfunction in 6-hydroxydopamine-induced and A53T mutant α-synuclein overexpression rat models of PD. Moreover, KDS2010 showed virtually no toxicity or side effects in non-human primates. KDS2010 could be a next-generation therapeutic candidate for PD. Supplementary Information The online version contains supplementary material available at 10.1007/s13311-021-01097-4.

SUMMARYIn spinal cord injury (SCI), the scar-forming reactive astrocytes with upregulated GFAP proliferate aberrantly near the injury site, allowing themselves as a prime target for transdifferentiation into neurons to replenish dead neurons. However, the conventional use of GFAP promoter to target reactive astrocytes has two inherent problems: inadvertent conversion of normal astrocytes and low efficiency due to progressive weakening of promoter activity during transdifferentiation. Here, we report that the scar-forming reactive astrocytes are selectively transdifferentiated into neurons with 87% efficiency and 96% specificity via TRANsCre-DIONE, a combination of the split-Cre system under two different promoters of GFAP and Lcn2 and a Cre-loxP-dependent inversion and expression of Neurog2 under the strong EF1α promoter. After SCI, TRANsCre-DIONE caused transdifferentiation into Isl1-positive motor neurons, reduced astrogliosis, enhanced regeneration in surrounding cells, and a significant motor recovery. Our study proposes TRANsCre-DIONE as the next-generation therapeutic approach for patients suffering from SCI.HighlightsTRANsCre-DIONE converts reactive astrocyte into neuron by over-expression of Neurog2 Reactive astrocytes are targeted using split-Cre under two promoters, GFAP and Lcn2 TRANsCre-DIONE reduces reactivity, replaces dead neurons and alleviates symptom of SCI Transdifferentiated-neurons are GABA+ in the striatum and Isl1+ in the spinal cord

Background and PurposeMonoamine oxidase-B (MAO-B) is a long-standing therapeutic target for Parkinson’s disease (PD), however, previous clinical studies demonstrated discouraging effects of currently available irreversible MAO-B inhibitors. Since KDS2010, a novel, potent, selective, and reversible MAO-B inhibitor, has been developed, here we tested its therapeutic potential in animal models of PD.Experimental ApproachWe designed and synthesized α-aminoamide derivatives and compared the specificity to MAO-B and reversibility of each compound with KDS2010. To investigate the in vivo therapeutic effect, we used MPTP mouse model with two different regimes of 3-day administration (pre-treatment or post-treatment) and 30-day administration. We assessed the therapeutic potential using behavioral and immunohistochemical analyses. Additionally, the functional recovery by KDS2010 was tested in 6-hydroxydopamine-induced and A53T-alpha-synuclein overexpression models. Lastly, to validate the potential as a clinical drug candidate, we investigated the pharmacokinetics and toxicity of KDS2010 in non-human primates.Key ResultsKDS2010 showed the highest potency, specificity, and reversibility among the α-aminoamide derivatives, with high bioavailability (>100%) and BBB permeability. KDS2010 also showed significant neuroprotective and anti-neuroinflammatory effects in the nigrostriatal pathway, leading to an alleviation of MPTP-induced parkinsonism in all administration regimes. In particular, the therapeutic effect of KDS2010 was superior to selegiline, an irreversible MAO-B inhibitor. KDS2010 also showed a potent therapeutic effect in 6-hydroxydopamine and A53T models. Moreover, KDS2010 showed virtually no toxicity or side-effect in non-human primates.Conclusion and ImplicationsKDS2010 shows excellent therapeutic potential and safety in various PD animal models. KDS2010, therefore, could be a next-generation therapeutic candidate for PD.Representative SchematicWhat is already knownKDS2010 is a recently developed potent, selective, and reversible MAO-B inhibitor.MAO-B is critical for PD pathology through astrocytic GABA and H2O2 synthesis.What this study addsKDS2010 treatment dramatically recovers from PD-related pathology and motor deficit after pre- and post-treatment regimes in several animal models of PD.KDS2010 exhibits low toxicity and excellent pharmacokinetic profile in non-human primates.What is the clinical significance?KDS2010 is a safe and promising therapeutic candidate for Parkinson’s disease.Reversible MAO-B inhibitors could be more effective for treatment of Parkinson’s disease, overcoming the short-lived actions of irreversible MAO-B inhibitors.

High-dose radiation-induced tissue damage is a major limiting factor in the medical application of nuclear technology. Herein, we tested 28-day repeated-dose toxicity of KMRC011, an agonist of toll-like receptor (TLR) 5, which is being developed as a medical countermeasure for radiation, using cynomolgus monkeys. KMRC011 (0.01, 0.02 or 0.04 mg/kg/day) was intramuscularly injected once daily for 4 weeks, and each two monkeys in both control and 0.04 mg/kg/day group were observed for an additional 2-week recovery period. There were no dose-related toxicological changes in mortality, clinical observations, body weight, food consumption, ophthalmological findings, electrocardiographs, coagulation, serum chemistry, organ weights, or urinalysis and urine chemistry. Although treatment-related changes, such as increased white blood cells, increased absolute and relative neutrophils, decreased relative lymphocytes and inflammatory lesions, were noted in the maximum dose group, these findings were not observed after the 2-week recovery period. Further, we considered that the kidneys and heart may be target organs of TLR5 agonists, as well as the spleen, and that autophagic signals can be triggered in tissue damage and the repair process. Importantly, accumulation of p62 protein, an indicator of autophagy, and a decrease of caveolin-1 protein, a regulator of TLR5 protein half-life, were found in both tissues from the highest dose group. Therefore, we conclude that the no-observed-adverse-effect level for KMRC011 may be greater than 0.04 mg/kg/day in male and female monkeys. Additionally, we propose that further studies are needed to identify the molecular signals, which are related to KMRC011-induced adverse effects.

Ginseng (Panax ginseng) is commonly used in Asia as a medicinal herb. In particular, fermented ginseng, GBCK25, has been recently developed to increase ginsenoside absorption. It also has other beneficial biological effects such as hemodynamic and anti-inflammation functions. Here, we investigated the potential toxicity of GBCK25 in Sprague–Dawley rats following 13 weeks of GBCK25 treatment by oral gavage at doses of 250, 500, or 1000 mg/kg/day and reversible toxic effects over a 4-week recovery phase. Ten male and female rats per group were randomly allocated to the main toxicology groups and five male and female rats per group were allocated to the 0 and 1000 mg/kg/day recovery groups, respectively. There was no mortality; significant clinical toxicity or microscopic findings; and changes in body weight, food consumption, hematological parameters, serum biochemistry, or absolute and relative organ weights in any of the groups. In conclusion, there were no toxicological changes upon repeated oral gavage of GBCK25 at doses of 250, 500, or 1000 mg/kg/day in Sprague–Dawley rats over 13 weeks. The no-observed-adverse-effect level of GBCK25 was 1000 mg/kg/day in both sexes of Sprague–Dawley rat.

Repeated dose oral toxicity and toxicokinetic of KDS2010, a new drug for Parkinson's disease, was investigated after 4-week repeated oral administration at 30, 50, 75, or 100 mg/kg/day in rats. Body weight and body weight gain decreased in rats of both sexes in the 75 and 100 mg/kg groups, and food consumption was reduced in male rats of the 75 and 100 mg/kg male groups. Histological alterations were observed in the kidney (urothelial hyperplasia, inflammatory cell infiltration in the renal pelvis, tubular vacuolation/degeneration, basophilic tubules, and hyaline droplets in the proximal tubules) of the 75 and 100 mg/kg male groups and the 50 and 100 mg/kg female groups. The 75 and 100 mg/kg male groups showed adverse effect in the testes (degeneration/exfoliation of germ cells, seminiferous tubules atrophy) and epididymis (cellular debris, oligospermia). These changes were partially recovered after a 2-week recovery period. However, basophilic tubules and hyaline droplets in the proximal tubules in the kidney and germ cell degeneration/exfoliation in the testis were not recovered. In toxicokinetics study, systemic exposure to KDS2010 increased proportionally in both sexes by in a dose -dependent manner. In addition, repeated administration for 4 weeks led to increased tendency of systemic exposure in both sexes compared with that in Day 1. In conclusion, KDS2010 was shown to target the kidney and testis with a no-observed-adverse-effect level of 50 and 30 mg/kg/day for males and females, respectively.

High-dose radiation-induced tissue damage is a major limiting factor in the medical application of nuclear technology. Herein, we tested 28-day repeated-dose toxicity of KMRC011, an agonist of toll-like receptor (TLR) 5, which is being developed as a medical countermeasure for radiation, using cynomolgus monkeys. KMRC011 (0.01, 0.02 or 0.04 mg/kg/day) was intramuscularly injected once daily for 4 weeks, and each two monkeys in both control and 0.04 mg/kg/day group were observed for an additional 2-week recovery period. There were no dose-related toxicological changes in mortality, clinical observations, body weight, food consumption, ophthalmological findings, electrocardiographs, coagulation, serum chemistry, organ weights, or urinalysis and urine chemistry. Although treatment-related changes, such as increased white blood cells, increased absolute and relative neutrophils, decreased relative lymphocytes and inflammatory lesions, were noted in the maximum dose group, these findings were not observed after the 2-week recovery period. Further, we considered that the kidneys and heart may be target organs of TLR5 agonists, as well as the spleen, and that autophagic signals can be triggered in tissue damage and the repair process. Importantly, accumulation of p62 protein, an indicator of autophagy, and a decrease of caveolin-1 protein, a regulator of TLR5 protein half-life, were found in both tissues from the highest dose group. Therefore, we conclude that the no-observed-adverse-effect level for KMRC011 may be greater than 0.04 mg/kg/day in male and female monkeys. Additionally, we propose that further studies are needed to identify the molecular signals, which are related to KMRC011-induced adverse effects.

Many researchers are using viruses to deliver genes of interest into the brains of laboratory animals. However, certain target brain cells are not easily infected by viruses. Moreover, the differential tropism of different viruses in monkey brain is not well established. We investigated the cellular tropism of lentivirus and adeno-associated virus (AAV) toward neuron and glia in the brain of cynomolgus monkeys (Macaca fascularis). Lentivirus and AAV were injected into putamen of the monkey brain. One month after injection, monkeys were sacrificed, and then the presence of viral infection by expression of reporter fluorescence proteins was examined. Tissues were sectioned and stained with NeuN and GFAP antibodies for identifying neuronal cells or astrocytes, respectively, and viral reporter GFP-expressing cells were counted. We found that while lentivirus infected mostly astrocytes, AAV infected neurons at a higher rate than astrocytes. Moreover, astrocytes showed reactiveness when cells were infected by virus, likely due to virus-mediated neuroinflammation. The Sholl analysis was done to compare the hypertrophy of infected and uninfected astrocytes by virus. The lentivirus infected astrocytes showed negligible hypertrophy whereas AAV infected astrocytes showed significant changes in morphology, compared to uninfected astrocytes. In the brain of cynomolgus monkey, lentivirus shows tropism for astrocytes over neurons without much reactivity in astrocytes, whereas AAV shows tropism for neurons over glial cells with a significant reactivity in astrocytes. We conclude that AAV is best-suited for gene delivery to neurons, whereas lentivirus is the best choice for gene delivery to astrocytes in the brain of cynomolgus monkeys.