Journal of Antimicrobial Chemotherapy (2002) 49, 953-959
© 2002 The British Society for Antimicrobial Chemotherapy
Regulation of fluoroquinolone uptake by human neutrophils: involvement of mitogen-activated protein kinase
1Department of Pharmacology and 3Medical Education Development Center, Gifu University School of Medicine, 40-Tsukasamachi, Gifu 500-8705; 2Department of Orthopedic Surgery, Nagoya City University Medical School, Nagoya 467-8601; 4Department of Drug Metabolism, Drug Safety Center, Tokushima Research Institute, Otsuka Pharmaceutical Co., Ltd, Tokushima 771-0192, Japan
Received 24 September 2001; returned 13 December 2001; revised 28 January 2002; accepted 28 February 2002.
Although human neutrophils actively internalize fluoroquinolones, the precise uptake mechanism is not fully understood. In this study, we investigated the role of protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) in fluoroquinolone uptake in neutrophils. Spontaneous grepafloxacin uptake was significantly enhanced by SB203580, a p38 MAPK inhibitor, in a dose-dependent manner, but not by PD98059, a specific inhibitor of the upstream kinase that activates p44/42 MAPK. Neither inhibitor affected spontaneous ciprofloxacin or ofloxacin uptake. Phorbol myristate acetate (PMA) treatment enhanced ciprofloxacin uptake, whereas it reduced grepafloxacin uptake. These effects by PMA were significantly inhibited by the pretreatment of neutrophils with GF109203X, a specific inhibitor of PKC. PMA had no effect on ofloxacin uptake. The PMA-induced enhancement of ciprofloxacin uptake was inhibited by PD98059, but not by SB203580. On the other hand, the PMA-induced reduction of grepafloxacin uptake was not inhibited by either MAPK inhibitor. Grepafloxacin, but not ciprofloxacin or ofloxacin, strongly phosphorylated p38 MAPK. This phosphorylation of p38 MAPK was not inhibited by GF109203X pretreatment. None of these three fluoroquinolones phosphorylated p44/42 MAPK. PMA phosphorylated both p38 and p44/42 MAPK. These findings indicate that grepafloxacin negatively regulates its uptake in neutrophils, and p38 MAPK activation is involved in this down-regulation of grepafloxacin uptake. Ciprofloxacin uptake is positively regulated by the activation of PKC, and p44/42 MAPK activation is involved in this up-regulation. Neither PKC, p38 nor p44/42 MAPK is involved in the regulation of ofloxacin uptake.
Keywords: fluoroquinolone, human neutrophils, MAPK, PKC
* Corresponding author. Tel: +81-58-267-2233; Fax: +81-58-267-2959; E-mail: mniwa{at}cc.gifu-u.ac.jp
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  M. Niwa, Y. Kanamori, K. Hotta, H. Matsuno, O. Kozawa, S. Fujimoto, and T. Uematsu Priming by grepafloxacin on respiratory burst of human neutrophils: its possible mechanism J. Antimicrob. Chemother., October 1, 2002; 50(4): 469 - 478. [Abstract] [Full Text] [PDF]
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