title: Cellular accumulation and activity of quinolones in ciprofloxacin-resistant J774 macrophages.
abstract: Ciprofloxacin is the substrate for a multidrug resistance-related protein (MRP)-like multidrug transporter in J774 mouse macrophages, which also modestly affects levofloxacin but only marginally affects garenoxacin and moxifloxacin (J.-M. Michot et al., Antimicrob. Agents Chemother. 49:2429-2437, 2005). Two clones of ciprofloxacin-resistant cells were obtained by a stepwise increase in drug concentration (from 34 to 51 to 68 mg/liter) in the culture fluid. Compared to wild-type cells, ciprofloxacin-resistant cells showed (i) a markedly reduced ciprofloxacin accumulation (12% of control) and (ii) a two- to threefold lower sensitivity to the enhancing effect exerted by MRP-inhibitors (probenecid and MK571) on ciprofloxacin accumulation or by ciprofloxacin itself. ATP-depletion brought ciprofloxacin accumulation to similarly high levels in both wild-type and ciprofloxacin-resistant cells. Garenoxacin and moxifloxacin accumulation remained unaffected, and levofloxacin showed an intermediate behavior. DNA and protein synthesis were not impaired in ciprofloxacin-resistant cells for ciprofloxacin concentrations up to 100 mg/liter (approximately 85 and 55% inhibition, respectively, in wild-type cells). In Listeria monocytogenes-infected ciprofloxacin-resistant cells, 12-fold higher extracellular concentrations of ciprofloxacin were needed to show a bacteriostatic effect in comparison with wild-type cells. The data suggest that the resistance mechanism is mediated by an overexpression and/or increased activity of the MRP-like ciprofloxacin transporter expressed at a basal level in wild-type J774 macrophages, which modulates both the intracellular pharmacokinetics and activity of ciprofloxacin.
authors.affiliation: Unité de Pharmacologie Cellulaire et Moléculaire, UCL 7370, avenue Mounier 73, 1200 Brussels, Belgium.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Michot
authors.forename: Marie F
authors.initials: MF
authors.lastname: Heremans
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Caceres
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Mingeot-Leclercq
authors.forename: Paul M
authors.initials: PM
authors.lastname: Tulkens
authors.forename: Françoise
authors.initials: F
authors.lastname: Van Bambeke
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism*; D002460:Cell Line; D002939:Ciprofloxacin / Q000378:metabolism*; D002999:Clone Cells / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D018432:Drug Resistance, Multiple / Q000235:genetics*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D015363:Quinolones / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D015363:Quinolones; D002939:Ciprofloxacin