Calcium-sensing receptor antagonism or lithium treatment ameliorates aminoglycoside-induced cell death in renal epithelial cells

Abstract

The aminoglycoside antibiotic gentamicin elicits proximal tubular toxicity and cell death. In calcium-sensing receptor (CaR)-transfected HEK-293 (CaR-HEK) cells and CaR-expressing proximal tubule-derived opossum kidney (OK) cells, chronic gentamicin treatment elicits dose-dependent, caspase-mediated apoptotic cell death. Here we investigated whether the renal cell toxicity of the CaR agonist gentamicin could be prevented by CaR antagonism or by lithium cotreatment which may interfere with receptor-mediated signalling. Chronic treatment of OK and CaR-HEK cells with low concentrations of gentamicin elicited cell death, an effect that was ameliorated by cotreatment with the CaR negative allosteric modulator (calcilytic) NPS-89636. This calcilytic also attenuated CaR agonist-induced ERK activation in these cells. In addition, 1 mM LiCl, equivalent to its therapeutic plasma concentration, also inhibited gentamicin-induced toxicity in both cell types. This protective effect of lithium was not due to the disruption of phosphatidylinositol-mediated gentamicin uptake as the cellular entry of Texas red-conjugated gentamicin into OK and CaR-HEK cells was unchanged by lithium treatment. However, the protective effect of lithium was mimicked by glycogen synthase 3beta inhibition. Together, these data implicate CaR activation and a lithium-inhibitable signalling pathway in the induction of cell death by gentamicin in renal epithelial cells in culture.

Protective Effects ofN-Acetylcysteine Amide (NACA) on Gentamicin-Induced Apoptosis in LLC-PK1 Cells

“…The characteristic apoptotic morphological features were elicited by a significantly higher Gen concentration than the target plasma concentration aimed for in antibiotic therapy. 10,11 This phenomenon has been reported previously 3,12,13 and may reflect low uptake of Gen in vitro. 4,13 p38 MAPK plays an important role in inflammatory responses and apoptosis.…”

“…10,11 This phenomenon has been reported previously 3,12,13 and may reflect low uptake of Gen in vitro. 4,13 p38 MAPK plays an important role in inflammatory responses and apoptosis. 14 Here we report that Gen causes p38 MAPK phosphorylation and iNOS induction and that the specific p38 MAPK inhibitor SB203580 and the selective iNOS inhibitor AG reduce Gen-induced apoptosis.…”

Statins inhibit aminoglycoside accumulation and cytotoxicity to renal proximal tubule cells

“…Additionally, the optimal concentration required in vivo for efficacy is around 20 times lower than the concentration used in vitro. Thus, one possible refinement of our in vitro model might be to use lower AG concentration over longer time periods [31]. However, it is important to note that (a) although the concentrations we have used are higher than those attained for efficacy, many patients achieve much higher concentrations, which is when they run into problems with nephrotoxicity; and (b) gentamicin toxicity in vivo does not solely depend on the plasma concentration, but more so A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 A c c e p t e d M a n u s c r i p …”

“…OK cells retain megalin-mediated protein binding and uptake, dependent on GTP-protein function, comparable to in vivo situations [14,15,29,30] and have previously been used to investigate AG cytotoxicity [31] and the biochemistry of statin renal transport [32]. We also cultured OK cells on trans-well membrane inserts to promote polarity and megalin expression [33].…”

Biomimetic Membranes as a Tool to Study Competitive Ion-Exchange Processes on Biologically Active Sites

“…The importance of the effects of Ca 2+ , Mg 2+ and ATP and other phosphorylated species on cardiac action potentials was recently as well emphasized (Michailova & McCulloch, 2008). A similar case of a competitive ion mechanism can be in interaction of the exogenous lithium ion with negatively-charged inositol phospholipids which is considered to be relevant in treatment of bipolar disorders (Atack at al., 1995;Gibbons at al., 2008). Presented here potential-dependent local concentration redistribution of ions at the membrane binding sites undoubtedly adds a new dimension in interpretation of above effects.…”