Lipophilic cationic drugs increase the permeability of lysosomal membranes in a cell culture system

Abstract

Lysosomes accumulate many drugs several fold higher compared to their extracellular concentration. This mechanism is believed to be responsible for many pharmacological effects. So far, uptake and release kinetics are largely unknown and interactions between concomitantly administered drugs often provoke mutual interference. In this study, we addressed these questions in a cell culture model. The molecular mechanism for lysosomal uptake kinetics was analyzed by live cell fluorescence microscopy in SY5Y cells using four drugs (amantadine, amitriptyline, cinnarizine, flavoxate) with different physicochemical properties. Drugs with higher lipophilicity accumulated more extensively within lysosomes, whereas a higher pK(a) value was associated with a more rapid uptake. The drug-induced displacement of LysoTracker was neither caused by elevation of intra-lysosomal pH, nor by increased lysosomal volume. We extended our previously developed numerical single cell model by introducing a dynamic feedback mechanism. The empirical data were in good agreement with the results obtained from the numerical model. The experimental data and results from the numerical model lead to the conclusion that intra-lysosomal accumulation of lipophilic xenobiotics enhances lysosomal membrane permeability. Manipulation of lysosomal membrane permeability might be useful to overcome, for example, multi-drug resistance by altering subcellular drug distribution.

Lysosomal Sequestration Determines Intracellular Imatinib Levels

“…In line with our observations, it has been reported that drugs that sequester to lysosomes can reach final intracellular concentrations that are much higher than the drug concentrations in the surrounding medium (Kornhuber et al, 2010;Fu et al, 2014).…”

“…As amantadine accumulates preferentially in lysosomes (Kornhuber et al, 2010), we reasoned that amantadine may prevent imatinib from being sequestered into lysosomes, thereby decreasing the IUR of imatinib. Therefore, we investigated whether the IUR of imatinib in HEK293/Neo, K562, SD-1, and GIST-T1 cells was inhibited by bafilomycin A1, a strong inhibitor of the vacuolar type H(1)-ATPase (Mattsson et al, 1991), and NH 4 Cl, a well known lysosomotropic compound.…”

Cationic liposomes promote antigen cross-presentation in dendritic cells by alkalizing the lysosomal pH and limiting the degradation of antigens

“…4,40,41 Our data demonstrate that the ability of nanomaterials to regulate lysosomal pH of the target APCs plays a major role in antigen cross-presentation and elicitation of CD8 + T-cell response. Based on our data presented here as well as other previous reports suggesting endolysosomal destabilization triggered by CLs and lipophilic cationic drugs, 42,43 we speculate that CL-mediated alkalization of lysosomal pH in DCs reduces the extent or kinetics of antigen degradation, which leads to CL-induced disruption of endolysosomal membranes, cytosolic delivery of protein antigens, and ultimately, promotion of antigen cross-presentation and cross-priming of antigen-specific CD8 + T-cells. To address these issues, future studies will need to further delineate the underlining mechanisms of CL-mediated cross-presentation and cross-priming and to validate the results in vivo.…”

Annexin A5 stimulates autophagy and inhibits endocytosis

“…3B, KH and IAA in the histogram) and with LysoTracker Red (see Fig. 3A, two upper panels and KH and IAA in the histogram below), a membrane-diffusible probe that accumulates in acidic organelles, especially lysosomes (Kornhuber et al, 2010), was higher in KH than in IAA. Interestingly, the cellular localisation of annexin A5 is different in the two media.…”