Investigating Nephrotoxicity of Polymyxin Derivatives by Mapping Renal Distribution Using Mass Spectrometry Imaging

Abstract

Colistin and polymyxin B are effective treatment options for Gram-negative resistant bacteria but are used as last-line therapy due to their dose-limiting nephrotoxicity. A critical factor in developing safer polymyxin analogues is understanding accumulation of the drugs and their metabolites, which is currently limited due to the lack of effective techniques for analysis of these challenging molecules. Mass spectrometry imaging (MSI) allows direct detection of targets (drugs, metabolites, and endogenous compounds) from tissue sections. The presented study exemplifies the utility of MSI by measuring the distribution of polymyxin B1, colistin, and polymyxin B nonapeptide (PMBN) within dosed rat kidney tissue sections. The label-free MSI analysis revealed that the nephrotoxic compounds (polymyxin B1 and colistin) preferentially accumulated in the renal cortical region. The less nephrotoxic analogue, polymyxin B nonapeptide, was more uniformly distributed throughout the kidney. In addition, metabolites of the dosed compounds were detected by MSI. Kidney homogenates were analyzed using LC/MS/MS to determine total drug exposure and for metabolite identification. To our knowledge, this is the first time such techniques have been utilized to measure the distribution of polymyxin drugs and their metabolites. By simultaneously detecting the distribution of drug and drug metabolites, MSI offers a powerful alternative to tissue homogenization analysis and label or antibody-based imaging.

Imaging mass spectrometry in drug development and toxicology

“…The major advantage of MALDI IMS for distribution studies is the possibility to simultaneously detect the parent molecule and its metabolites (Nilsson et al 2015). However, detection of these small molecules is hampered by interference of matrix cluster ions.…”

Analysis of small molecule antibody–drug conjugate catabolites in rat liver and tumor tissue by liquid extraction surface analysis micro‐capillary liquid chromatography/tandem mass spectrometry

“…Recently, Kertesz et al improved the spatial resolution of the LESA approach up to 0.1 mm . Thus, further discrimination of different tissue regions such as kidney cortex and medulla can be performed as described by Nilsson et al The injection volume was set to 500 nL since clogging of the micro‐capillary LC system was observed with higher injection volumes (1 and 2 μL). This was most likely due to the fact that particles were extracted from the tissue sections clogging the micro‐capillary tubings of the LC system.…”

Prevalence of acute renal injury in patients treated with colistin

“…La nefrotoxicidad no parece estar relacionada con la dosis diaria (22)(23)(24) (mg/kg/día), sino más bien con la dosis total acumulada . La colistina se acumula en la región cortical del riñónespecialmente en las células del túbulo proximal donde los transportadores tubulares (25)(26)(27) reabsorben más de la droga .El estrés oxidativo, la apoptosis y alteraciones en los niveles de óxido (28) nítrico sintetasa también podrían jugar un rol importante en la nefrotoxicidad inducida por colistina .…”