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Comparative uptake of sparfloxacin and ciprofloxacin into human THP 1 monocytic cells
P Rispal1, J Grellet, C Celerier
1Department of Internal Medecine and Infectious Diseases, Haut-lévèque Hospital, Pessac, France.
Abstract:
The uptake of sparfloxacin (CAS 11542-93-9) by human monocytes was studied by comparison with ciprofloxacin (CAS 86393-32-0). The human monocytic THP 1 cells were incubated with the antibiotics for 2 h. Entry of antimicrobials into the cells was determined by means of a velocity gradient centrifugation technique and HPLC assay. Antibiotic uptake was expressed as the ratio of the intracellular to the extracellular drug concentration (IC/EC). Quinolones enter readily in monocytic cells but sparfloxacin is taken up more rapidly than ciprofloxacin. At steady-state the IC/EC ratio of sparfloxacin (9.07) is higher than IC/EC of ciprofloxacin (4.29). Characterization of quinolone uptake suggests that these drugs penetrate throughout the THP 1 membrane by passive diffusion. However, the results of the present study indicate that additional mechanisms may contribute to intracellular accumulation of ciprofloxacin and sparfloxacin. Gemfibrozil, an inhibitor of organic anion transport, increases the accumulation of ciprofloxacin but does not modify IC/EC of sparfloxacin. It can be concluded that human monocyte-like cells have functional organic anion transporters and that this way of secretion is quinolone selective.
Insights
Sparfloxacin uptake by human monocytes is faster than ciprofloxacin, indicating potential differences in cellular entry mechanisms. Human monocyte-like cells possess organic anion transporters that selectively influence quinolone secretion.
Area of Science:
- Pharmacology
- Cell Biology
- Drug Metabolism
Background:
- Human monocytes play a crucial role in immune responses and are targets for antimicrobial agents.
- Understanding the cellular uptake of fluoroquinolones like sparfloxacin and ciprofloxacin is vital for optimizing their therapeutic efficacy.
- Previous studies suggest passive diffusion as a primary mechanism for quinolone entry into cells.
Purpose of the Study:
- To compare the uptake kinetics of sparfloxacin and ciprofloxacin in human monocytic THP-1 cells.
- To investigate the potential role of organic anion transporters in the intracellular accumulation of these fluoroquinolones.
- To elucidate the mechanisms governing the differential cellular accumulation of sparfloxacin and ciprofloxacin.
Main Methods:
- Incubation of human monocytic THP-1 cells with sparfloxacin and ciprofloxacin for 2 hours.
- Determination of antimicrobial entry using velocity gradient centrifugation and High-Performance Liquid Chromatography (HPLC) assay.
- Calculation of intracellular to extracellular drug concentration ratio (IC/EC) to quantify uptake.
- Assessment of gemfibrozil's effect (an organic anion transport inhibitor) on drug accumulation.
Main Results:
- Sparfloxacin demonstrated a more rapid uptake into THP-1 cells compared to ciprofloxacin.
- The steady-state IC/EC ratio for sparfloxacin (9.07) was significantly higher than that for ciprofloxacin (4.29).
- Gemfibrozil increased ciprofloxacin accumulation but did not affect sparfloxacin accumulation, suggesting involvement of organic anion transporters in ciprofloxacin uptake.
Conclusions:
- Human monocyte-like cells possess functional organic anion transporters.
- These transporters exhibit selectivity, influencing the intracellular accumulation of quinolones.
- The findings suggest that while passive diffusion contributes to quinolone entry, active transport mechanisms also play a significant role, with differential involvement for sparfloxacin and ciprofloxacin.