Antibacterial and Immunosuppressive Effects of OPS-2071, a Candidate Therapy for Inflammatory Bowel Disease.

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Although many types of drug are used, clinical outcomes are still unsatisfactory. Previous studies have suggested that intestinal bacteria are involved in the pathogenesis of IBD. Accordingly, in an IBD model we evaluated the therapeutic effects of OPS-2071, a low-absorption quinolone antibacterial agent indicated for intestinal infection, and investigated its mechanism of action. METHODS: The therapeutic effects of OPS-2071 and comparison therapies were evaluated using naive CD4 + T cell-transfer IBD model mice. In vitro inhibition of LPS-induced TNF-α production and inhibitory effects on T cell responses stimulated using anti-CD3/CD28 antibody-loaded beads were evaluated using mouse splenocytes and human peripheral blood mononuclear cells. In addition, in vitro activities against bacteria implicated in IBD pathogenesis were tested. RESULTS: OPS-2071 dose-dependently decreased both colonic weight/length ratio and the colitis histological score as compared with the vehicle group. The therapeutic effect of OPS-2071 was equivalent to that of anti-IL-12/23 (p40) antibody. In vitro, OPS-2071 suppressed TNF-α production induced by LPS stimulation and T cell responses in a dose-dependent manner. At high concentrations, these effects were comparable to those of existing immunosuppressive agents, such as prednisolone, in both mouse and human cells. OPS-2071 also showed antibacterial activity against IBD-related bacteria. CONCLUSIONS: Our results suggest that OPS-2071 had both immunosuppressive and antibacterial effects. This dual effect makes OPS-2071 a unique and promising candidate for IBD.

In Vitro and In Vivo Antibacterial Activities of a Novel Quinolone Compound, OPS-2071, against Clostridioides difficile.

OPS-2071 is a novel quinolone antibacterial agent characterized by low oral absorption that reduces the risk of adverse events typical of fluoroquinolone class antibiotics. The in vitro and in vivo antibacterial activities of OPS-2071 against Clostridioides difficile were evaluated in comparison to vancomycin and fidaxomicin. OPS-2071 exhibited potent antibacterial activity against 54 clinically isolated C. difficile strains with a MIC of 0.125 µg/ml (MIC50) and 0.5 µg/ml (MIC90), making it more active than vancomycin on a concentration basis (MIC50, 2 µg/ml; MIC90, 4 µg/ml) and comparable to fidaxomicin (MIC50, 0.063 µg/ml; MIC90, 8 µg/ml). OPS-2071 showed equally potent antibacterial activity against both hypervirulent and nonhypervirulent strains, while a significant difference in susceptibility to fidaxomicin was observed. Spontaneous resistance to OPS-2071 and vancomycin was not observed; however, resistance to fidaxomicin was observed at 4× MIC. The mutant prevention concentration of OPS-2071 was 16-fold lower than those of fidaxomicin and vancomycin, and the postantibiotic effect of OPS-2071 was longer than those of fidaxomicin and vancomycin. Also, OPS-2071 showed low systemic exposure, with OPS-2071 having 2.9% oral bioavailability at 1 mg/kg in rats. Furthermore, OPS-2071 showed significant in vivo efficacy at 0.0313 mg/kg/day (50% effective doses), 39.0-fold and 52.1-fold lower than those of vancomycin and fidaxomicin, respectively, in a hamster model of C. difficile infection. OPS-2071 has the potential to become a new therapeutic option for treating C. difficile infection.