2. Academic Validation
  3. Loxapine, an antipsychotic drug, suppresses intracellular multiple-antibiotic-resistant Salmonella enterica serovar Typhimurium in macrophages

Loxapine, an antipsychotic drug, suppresses intracellular multiple-antibiotic-resistant Salmonella enterica serovar Typhimurium in macrophages

  • J Microbiol Immunol Infect. 2019 Aug;52(4):638-647. doi: 10.1016/j.jmii.2019.05.006.
Ching-Yi Yang 1,  Cheng-Yun Hsu 1,  Chun-Sheng Fang 2,  Chung-Wai Shiau 3,  Ching S Chen 4,  Hao-Chieh Chiu 5
Affiliations

Affiliations

  • 1 Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 10048, Taiwan.
  • 2 Drug Development Center, China Medical University, Taichung 40402, Taiwan.
  • 3 Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei 11221, Taiwan.
  • 4 Drug Development Center, China Medical University, Taichung 40402, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40447, Taiwan.
  • 5 Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 10048, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 10002, Taiwan. Electronic address: [email protected].
PMID: 31239204 DOI: 10.1016/j.jmii.2019.05.006
Abstract

Background: The emergence of multiple-antibiotic-resistant (MAR) Salmonella has been a serious threat worldwide. Salmonella can invade into host cells and evade the attacks of host humoral defenses and Antibiotics. Thus, a new Antibacterial agent capable of inhibiting intracellular Salmonella is highly needed.

Methods: The anti-intracellular activity and cytotoxicity of drugs on intracellular bacteria and macrophages were assayed using intracellular CFU assay and MTT cell viability assay, respectively. The uptake of gentamicin into macrophage and the effect of Autophagy Inhibitor on loxapine's anti-intracellular Salmonella activity were assessed by using image-based high-content system. The expression of Bacterial genes was measured by Real-Time PCR. The efflux pump activity of bacteria was measured by Hoechst accumulation assays.

Results: With our efforts, an antipsychotic drug, loxapine, was identified to exhibit high potency in suppressing intracellular MAR S. Typhimurium, Staphylococcus aureus, Shigella flexneri or Yersinia enterocolitica. Subsequent investigations indicated that loxapine's anti-intracellular bacteria activity was not associated with increased penetration of gentamicin into bacteria and macrophages. Loxapine didn't inhibit Bacterial growth in broth at concentration up to 500 μM and has no effect on Salmonella's type III secretion system genes' expression. Blockage of Autophagy also didn't reverse loxapine's anti-intracellular activity. Lastly, loxapine suppressed Bacterial efflux pump activity in all bacteria tested.

Conclusion: Altogether, our data suggested that loxapine might suppress intracellular bacteria through inhibiting of Bacterial efflux pumps. In LIGHT of its unique activity, loxapine represents a promising lead compound with translational potential for the development of a new Antibacterial agent against intracellular bacteria.

Keywords

Autophagy; Efflux pump; High-content assay; Phenothiazine; Type III secretion system.

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