{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T12:29:02Z","timestamp":1790771342274,"version":"4.1.0"},"reference-count":39,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2024,3,12]],"date-time":"2024-03-12T00:00:00Z","timestamp":1710201600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institute of Allergy and Infectious Diseases of the National Institutes of Health","award":["R01AI146160"],"award-info":[{"award-number":["R01AI146160"]}]},{"name":"National Institute of Allergy and Infectious Diseases of the National Institutes of Health","award":["R01HL167828"],"award-info":[{"award-number":["R01HL167828"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pharmaceutics"],"abstract":"<jats:p>Accumulation of polymyxins in the lung epithelial cells can lead to increased mitochondrial oxidative stress and pulmonary toxicity. Aminoglycosides and polymyxins are used, via intravenous and pulmonary delivery, against multidrug-resistant Gram-negative pathogens. Our recent in vitro and animal studies demonstrated that the co-administration of polymyxins with aminoglycosides decreases polymyxin-induced pulmonary toxicity. The aim of this study was to investigate the in vitro transport and uptake of polymyxin B and tobramycin in human lung epithelial Calu-3 cells and the mechanism of reduced pulmonary toxicity resulting from this combination. Transport, intracellular localization, and accumulation of polymyxin B and tobramycin were investigated using doses of 30 mg\/L polymyxin B, 70 mg\/L tobramycin, and the combination of both. Adding tobramycin significantly (p &lt; 0.05) decreased the polymyxin B-induced cytotoxicity in Calu-3 cells. The combination treatment significantly reduced the transport and uptake of polymyxin B and tobramycin in Calu-3 cells, compared to each drug alone, which supported the reduced pulmonary toxicity. We hypothesized that cellular uptake of polymyxin B and tobramycin shared a common transporter, megalin. We further investigated the megalin expression of Calu-3 cells using confocal microscopy and evaluated megalin activity using a megalin substrate, FITC-BSA, and a megalin inhibitor, sodium maleate. Both polymyxin B and tobramycin significantly inhibited FITC-BSA uptake by Calu-3 cells in a concentration-dependent manner. Sodium maleate substantially inhibited polymyxin B and tobramycin transport and cellular accumulation in the Calu-3 cell monolayer. Our study demonstrated that the significantly reduced uptake of polymyxin B and tobramycin in Calu-3 cells is attributed to the mechanism of action that determines that polymyxin B and tobramycin share a common transporter, megalin.<\/jats:p>","DOI":"10.3390\/pharmaceutics16030389","type":"journal-article","created":{"date-parts":[[2024,3,12]],"date-time":"2024-03-12T12:14:40Z","timestamp":1710245680000},"page":"389","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Tobramycin Reduces Pulmonary Toxicity of Polymyxin B via Inhibiting the Megalin-Mediated Drug Uptake in the Human Lung Epithelial Cells"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5221-2502","authenticated-orcid":false,"given":"Maizbha Uddin","family":"Ahmed","sequence":"first","affiliation":[{"name":"Department of Industrial and Molecular Pharmaceutics, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Li","sequence":"additional","affiliation":[{"name":"Monash Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1438-6990","authenticated-orcid":false,"given":"Qi (Tony)","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Industrial and Molecular Pharmaceutics, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,3,12]]},"reference":[{"key":"ref_1","first-page":"3291","article-title":"New pharmacokinetic\/pharmacodynamic studies of systemically administered colistin against Pseudomonas aeruginosa and Acinetobacter baumannii in mouse thigh and lung infection models: Smaller response in lung infection","volume":"70","author":"Cheah","year":"2015","journal-title":"J. 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