Sodium-Glucose Transporter-2 (SGLT2; SLC5A2) Enhances Cellular Uptake of Aminoglycosides

Abstract

Aminoglycoside antibiotics, like gentamicin, continue to be clinically essential worldwide to treat life-threatening bacterial infections. Yet, the ototoxic and nephrotoxic side-effects of these drugs remain serious complications. A major site of gentamicin uptake and toxicity resides within kidney proximal tubules that also heavily express electrogenic sodium-glucose transporter-2 (SGLT2; SLC5A2) in vivo. We hypothesized that SGLT2 traffics gentamicin, and promotes cellular toxicity. We confirmed in vitro expression of SGLT2 in proximal tubule-derived KPT2 cells, and absence in distal tubule-derived KDT3 cells. D-glucose competitively decreased the uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent analog of glucose, and fluorescently-tagged gentamicin (GTTR) by KPT2 cells. Phlorizin, an SGLT2 antagonist, strongly inhibited uptake of 2-NBDG and GTTR by KPT2 cells in a dose- and time-dependent manner. GTTR uptake was elevated in KDT3 cells transfected with SGLT2 (compared to controls); and this enhanced uptake was attenuated by phlorizin. Knock-down of SGLT2 expression by siRNA reduced gentamicin-induced cytotoxicity. In vivo, SGLT2 was robustly expressed in kidney proximal tubule cells of heterozygous, but not null, mice. Phlorizin decreased GTTR uptake by kidney proximal tubule cells in Sglt2+/− mice, but not in Sglt2−/− mice. However, serum GTTR levels were elevated in Sglt2−/− mice compared to Sglt2+/− mice, and in phlorizin-treated Sglt2+/− mice compared to vehicle-treated Sglt2+/− mice. Loss of SGLT2 function by antagonism or by gene deletion did not affect gentamicin cochlear loading or auditory function. Phlorizin did not protect wild-type mice from kanamycin-induced ototoxicity. We conclude that SGLT2 can traffic gentamicin and contribute to gentamicin-induced cytotoxicity.

Fluorescent aminoglycosides reveal intracellular trafficking routes in mechanosensory hair cells

“…It has been suggested that AGs enter through other channels including transient receptor potential channels (75)(76)(77). The sodium glucose transporter SLC5A2 may also play a role in AG transport in the kidney (78). Whatever additional mechanisms of uptake are active, our data suggest that these mechanisms are universally under control of MET activity in hair cells.…”

Endotoxemia-mediated inflammation potentiates aminoglycoside-induced ototoxicity

“…Aminoglycosides and GTTR can permeate through non-selective cation channels, including the MET channel expressed by hair cells (11, 12), and TRPV4 channels expressed by endothelial cells (70, 71). The sodium-glucose transporter-2 (SGLT2) traffics aminoglycosides into cells, and facilitates aminoglycoside-induced cytotoxicity (72). LPS treatment can upregulate endothelial cation channel expression (73).…”

“…ABRs to pure tones were used to ensure normal cochlear function prior to toxicity studies and determine threshold shifts following kanamycin treatment (20, 72). Briefly, needle electrodes were placed subcutaneously below the test ear, at the vertex, with a ground electrode near the paw.…”

Pseudomonas Aeruginosa : Arsenal of Resistance Mechanisms, Decades of Changing Resistance Profiles, and Future Antimicrobial Therapies

“…In another study, sodium-dependent glucose cotransporter 2 (SGLT2) was found to be specifically expressed in renal proximal tubules but weakly expressed in cochlear cells [80]. When SGLT2 expression in a murine kidney proximal tubule cell line was knocked down by siRNA, the cellular toxicity of aminoglycosides was reduced indicating an important role for SGLT2 in aminoglycoside tissue accumulation and nephorotoxicity [80]. Further investigation and understanding of aminoglycoside associated toxicity as well as chemical development of less toxic derivatives are required to alleviate the toxic effects and improve the antimicrobial benefits of aminoglycosides.…”

“…It has been reported that binding of amikacin to the endocytic receptor megalin and uptake of aminoglycosdies via the transient receptor potential vanilloid subtype 1 (TRPV1) channel and TRPV4 results in the accumulation of amikacin and other aminoglycosides in renal proximal tubules and hair cells leading to nephortoxocity and ototoxicity [78,79]. In another study, sodium-dependent glucose cotransporter 2 (SGLT2) was found to be specifically expressed in renal proximal tubules but weakly expressed in cochlear cells [80]. When SGLT2 expression in a murine kidney proximal tubule cell line was knocked down by siRNA, the cellular toxicity of aminoglycosides was reduced indicating an important role for SGLT2 in aminoglycoside tissue accumulation and nephorotoxicity [80].…”