Prophylactic Treatment with Baloxavir Protects Mice from Lethal Infection with Influenza A and B Viruses.

Influenza remains a worldwide health concern. Antiviral drugs are considered as one of the useful options for its prevention as a complementary measure to vaccination. Baloxavir acid selectively inhibits the cap-dependent endonuclease of influenza viruses and exhibits marked viral titre reduction in patients. Here, we describe the prophylactic potency of baloxavir acid against lethal infection with influenza A and B viruses in mice. BALB/c mice were subcutaneously administered once with baloxavir acid suspension, or orally administered once daily for 10 days with oseltamivir phosphate solution at human relevant doses. Next, the mice were intranasally inoculated with A/PR/8/34 (H1N1) or B/Hong Kong/5/72 strain at 24 to 96 h after the initial dosing. Prophylactic treatment with the antiviral drugs significantly reduced the lung viral titres and prolonged survival time. In particular, baloxavir acid showed a greater suppressive effect on lung viral titres compared to oseltamivir phosphate. In this model, baloxavir acid maintained significant prophylactic effects against influenza A and B virus infections when the plasma concentration at the time of infection was at least 0.88 and 3.58 ng/mL, respectively. The significant prophylactic efficacy observed in our mouse model suggests the potential utility of baloxavir marboxil for prophylaxis against influenza in humans.

Discovery of a novel olefin derivative as a highly potent and selective acetyl-CoA carboxylase 2 inhibitor with in vivo efficacy.

Novel acetyl-CoA carboxylase 2 (ACC2) selective inhibitors were identified by the conversion of the alkyne unit of A-908292 to the olefin linker. Modification of the center and left part of the lead compound 1b improved the ACC2 inhibitory activity and CYP450 inhibition profile, and afforded a highly selective ACC2 inhibitor 2e which showed in vivo efficacy in C57BL/6 mice.

Comparative Characterization of Hepatic Distribution and mRNA Reduction of Antisense Oligonucleotides Conjugated with Triantennary N-Acetyl Galactosamine and Lipophilic Ligands Targeting Apolipoprotein B.

TriantennaryN-acetyl galactosamine (GalNAc, GN3) and lipophilic ligands such as cholesterol andα-tocopherol conjugations dramatically improve the distribution and efficacy of second-generation antisense oligonucleotides (ASOs) in the whole liver. To characterize ligands for delivery to liver cells based on pharmacokinetics and efficacy, we used a locked nucleic acid gapmer of ASO targeting apolipoprotein B as a model compound and evaluated the amount of ASO and apolipoprotein B mRNA in the whole liver, hepatocytes, and nonparenchymal (NP) cells as well as plasma total cholesterol after administration of ASO conjugated with these ligands to mice. Compared with unconjugated ASO, GN3 conjugation increased the amount (7-fold) and efficacy (more than 10-fold) of ASO in hepatocytes only and showed higher efficacy than the increased rate of the amount of ASO. On the other hand, lipophilic ligand conjugations led to increased delivery (3- to 5-fold) and efficacy (5-fold) of ASO to both hepatocytes and NP cells. GN3 and lipophilic ligand conjugations increased the area under the curve of ASOs and the pharmacodynamic duration but did not change the half-life in hepatocytes and NP cells compared with unconjugated ASO. In the liver, the phosphodiester bond between ASO and these ligands was promptly cleaved to liberate unconjugated ASO. These ligand conjugations reduced plasma total cholesterol compared with unconjugated ASO, although these ASOs were well tolerated with no elevation in plasma transaminases. These findings could facilitate ligand selection tailored to liver cells expressed in disease-related genes and could contribute to the discovery and development of RNA interference-based therapy.

Cationic amino acid transporter 1-mediated L-arginine transport at the inner blood-retinal barrier.

The purpose of this study was to identify the transporter mediating l-arginine transport at the inner blood-retinal barrier (BRB). The apparent uptake clearance of [(3)H]L-arginine into the rat retina was found to be 118 microL/(min.g retina), supporting a carrier-mediated influx transport of L-arginine at the BRB. [(3)H]L-arginine uptake by a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2 cells), used as an in vitro model of the inner BRB, was primarily an Na(+)-independent and saturable process with Michaelis-Menten constants of 11.2 microM and 530 microM. This process was inhibited by rat cationic amino acid transporter (CAT) 1-specific small interfering RNA as well as substrates of CATs, L-arginine, L-lysine, and L-ornithine. The expression of cationic amino acid transporter (CAT) 1 mRNA was 25.9- and 796-fold greater than that of CAT3 in TR-iBRB2 and magnetically isolated rat retinal vascular endothelial cells, respectively. The expression of CAT1 protein was detected in TR-iBRB2 cells and immunostaining of CAT1 was observed along the rat retinal capillaries. In conclusion, CAT1 is localized in retinal capillary endothelial cells and at least in part mediates L-arginine transport at the inner BRB. This process seems to be closely involved in visual functions by supplying precursors of biologically important molecules like nitric oxide in the neural retina.