High affinity capture and concentration of quinacrine in polymorphonuclear neutrophils via vacuolar ATPase-mediated ion trapping: Comparison with other peripheral blood leukocytes and implications for the distribution of cationic drugs

Abstract

Many cationic drugs are concentrated in acidic cell compartments due to low retro-diffusion of the protonated molecule (ion trapping), with an ensuing vacuolar and autophagic cytopathology.In solid tissues, there is evidence that phagocytic cells, e.g., histiocytes, preferentially concentrate cationic drugs. We hypothesized that peripheral blood leukocytes could differentially take up a fluorescent model cation, quinacrine, depending on their phagocytic competence. Quinacrine transport parameters were determined in purified or total leukocyte suspensions at 37°C. Purified polymorphonuclear leukocytes (PMNLs, essentially neutrophils) exhibited a quinacrine uptake velocity inferior to that of lymphocytes, but a consistently higher affinity (apparent K M 1.1 vs. 6.3 µM, respectively). However, the vacuolar (V)-ATPase inhibitor bafilomycin A1 prevented quinacrine transport or initiated its release in either cell type. PMNLs capture most of the quinacrine added at low concentrations to fresh peripheral blood leukocytes compared with lymphocytes and monocytes (cytofluorometry). Accumulation of the autophagy marker LC3-II occurred rapidly and at low drug concentrations in quinacrine-treated PMNLs (significant at 2.5 µM, 2 h). Lymphocytes contained more LAMP1 than PMNLs, suggesting that the mass of lysosomes and late endosomes is a determinant of quinacrine uptake V max . PMNLs, however, exhibited the highest capacity for pinocytosis (uptake of fluorescent dextran into endosomes).The selectivity of quinacrine distribution in peripheral blood leukocytes may be determined by the collaboration of a non-concentrating plasma membrane transport mechanism, tentatively identified as pinocytosis in PMNLs, with V-ATPase-mediated concentration. Intracellular reservoirs of cationic drugs are a potential source of toxicity (e.g., loss of lysosomal function in phagocytes).

Autophagic flux inhibition and lysosomogenesis ensuing cellular capture and retention of the cationic drug quinacrine in murine models

“…1A ), thus qualifying more precisely as myofibroblasts ( Hinz, 2007 ). As reported for various cells of human origin ( Marceau et al, 2009 ; Marceau, Roy & Bouthillier, 2014 ; Roy et al, 2013 ), these cells from wild type C57BL/6 mice accumulated quinacrine under the form of perinuclear and cytosolic granules and vacuoles, depending on the drug concentration (250 nM–5 µM), as judged by the intrinsic green fluorescence of the drug ( Fig. 1B ).…”

“…The concentration of cationic drugs (weak bases) in acidic cell compartments is well documented, at least in cultured cells ( De Duve et al, 1974 ; Marceau et al, 2012 ) and freshly isolated peripheral blood leukocytes ( Roy et al, 2013 ). A general model is emerging: the proton pump vacuolar (V)-ATPase is the driving force that mediates the concentration and retention of such amines, mainly in the late endosome-lysosome continuum.…”

“…Intriguing tissue or cell type specificities were described for the formation of cationic drug reservoirs. Thus, in vitro , macrophages concentrate more amiodarone than do smooth muscle cells ( Morissette et al, 2009 ); freshly isolated neutrophils exhibit a higher affinity but lower V max than lymphocytes for the transport of quinacrine ( Roy et al, 2013 ). In vivo , the lipophilic amine clofazimine is redistributed from adipose tissue to macrophage-rich organs, such as the spleen and liver, as a function of time ( Baik et al, 2013 ).…”

“…In previous studies, we have exploited the inherently fluorescent drug quinacrine to perform quantitative transport and morphological studies of human cells ( Marceau et al, 2009 ; Roy et al, 2013 ; Marceau, Roy & Bouthillier, 2014 ). Formerly used as an antiprotozoal drug, quinacrine considerably accumulates over time during chronic dosing in tissues such as the liver, lungs and spleen in vivo ( Huang et al, 2006 ; Ehsanian, Van Waes & Feller, 2011 ).…”

Quinacrine Inhibits Candida albicans Growth and Filamentation at Neutral pH

“…The pharmacologic effects of QNC remain incompletely defined but include the inhibition of nucleic acid synthesis through DNA intercalation and antiprostaglandin and antiplatelet effects due to the inhibition of phospholipase A2 and antilipolytic activity, the inhibition of platelet aggregation, and accumulation within neutrophils (9)(10)(11)(12).…”