PURPOSE: Multidrug resistance (MDR) represents a major obstacle to the success of antimicrobial fluoroquinolone (FQ) therapy. MDR-associated efflux protein pumps antimicrobial agents out of the corneal cells, leading to suboptimal eradication of microbes. This article examines whether long-term FQ (levofloxacin, ofloxacin, and gatifloxacin) therapy can modify the MDR phenotype (P-glycoprotein [P-gp]) on corneal epithelial cells (Statens Seruminstitut Rabbit Cornea [SIRC]). METHODS: To study the effect of FQ, SIRC cells without any exposure to FQ (control) were compared with the cells exposed to ofloxacin, levofloxacin, and gatifloxacin at a concentration of 10 μg/mL for 3 weeks. Efflux activity of P-gp was assessed by in vitro uptake studies (fluorescent and radioactive), flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: In the presence of FQ, elevated P-gp expression was noted with uptake, flow cytometry, and qRT-PCR analyses. This study confirms that long-term exposure to antibiotics, particularly FQ, can induce overexpression of P-gp efflux transporter present on the corneal cells. P-gp overexpression is commonly noticed in anticancer drug resistance cell lines; however, for the first time, this report describes overexpression of P-gp due to FQ exposure. CONCLUSIONS: Based on this result, it is suggested that strategies should be developed and implemented not only to overcome resistance to ocular pathogen but also to FQ-induced cellular resistance.
PURPOSE: Multidrug resistance (MDR) represents a major obstacle to the success of antimicrobial fluoroquinolone (FQ) therapy. MDR-associated efflux protein pumps antimicrobial agents out of the corneal cells, leading to suboptimal eradication of microbes. This article examines whether long-term FQ (levofloxacin, ofloxacin, and gatifloxacin) therapy can modify the MDR phenotype (P-glycoprotein [P-gp]) on corneal epithelial cells (Statens Seruminstitut Rabbit Cornea [SIRC]). METHODS: To study the effect of FQ, SIRC cells without any exposure to FQ (control) were compared with the cells exposed to ofloxacin, levofloxacin, and gatifloxacin at a concentration of 10 μg/mL for 3 weeks. Efflux activity of P-gp was assessed by in vitro uptake studies (fluorescent and radioactive), flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: In the presence of FQ, elevated P-gp expression was noted with uptake, flow cytometry, and qRT-PCR analyses. This study confirms that long-term exposure to antibiotics, particularly FQ, can induce overexpression of P-gp efflux transporter present on the corneal cells. P-gp overexpression is commonly noticed in anticancer drug resistance cell lines; however, for the first time, this report describes overexpression of P-gp due to FQ exposure. CONCLUSIONS: Based on this result, it is suggested that strategies should be developed and implemented not only to overcome resistance to ocular pathogen but also to FQ-induced cellular resistance.
Authors: Robert W Robey; Kenneth K K To; Orsolya Polgar; Marius Dohse; Patricia Fetsch; Michael Dean; Susan E Bates Journal: Adv Drug Deliv Rev Date: 2008-12-16 Impact factor: 15.470