title: Polymyxin B Nephrotoxicity: From Organ to Cell Damage.
abstract: Polymyxins have a long history of dose-limiting toxicity, but the underlying mechanism of polymyxin B-induced nephrotoxicity is unclear. This study investigated the link between the nephrotoxic effects of polymyxin B on renal metabolic functions and mitochondrial morphology in rats and on the structural integrity of LLC-PK1 cells. Fifteen Wistar rats were divided into two groups: Saline group, rats received 3 mL/kg of 0.9% NaCl intraperitoneally (i.p.) once a day for 5 days; Polymyxin B group, rats received 4 mg/kg/day of polymyxin B i.p. once a day for 5 days. Renal function, renal hemodynamics, oxidative stress, mitochondrial injury and histological characteristics were assessed. Cell membrane damage was evaluated via lactate dehydrogenase and nitric oxide levels, cell viability, and apoptosis in cells exposed to 12.5 μM, 75 μM and 375 μM polymyxin B. Polymyxin B was immunolocated using Lissamine rhodamine-polymyxin B in LLC-PK1 cells. Polymyxin B administration in rats reduced creatinine clearance and increased renal vascular resistance and oxidative damage. Mitochondrial damage was confirmed by electron microscopy and cytosolic localization of cytochrome c. Histological analysis revealed tubular dilatation and necrosis in the renal cortex. The reduction in cell viability and the increase in apoptosis, lactate dehydrogenase levels and nitric oxide levels confirmed the cytotoxicity of polymyxin B. The incubation of LLC-PK1 cells resulted in mitochondrial localization of polymyxin B. This study demonstrates that polymyxin B nephrotoxicity is characterized by mitochondrial dysfunction and free radical generation in both LLC-PK1 cells and rat kidneys. These data also provide support for clinical studies on the side effects of polymyxin B.
authors.affiliation: Experimental Laboratory of Animal Models (LEMA), School of Nursing of the University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Maria de Fátima Fernandes
authors.initials: Mde F
authors.lastname: Vattimo
authors.affiliation: Experimental Laboratory of Animal Models (LEMA), School of Nursing of the University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Mirian
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Experimental Laboratory of Animal Models (LEMA), School of Nursing of the University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Cassiane Dezoti
authors.initials: CD
authors.lastname: da Fonseca
authors.affiliation: Experimental Laboratory of Animal Models (LEMA), School of Nursing of the University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Luciana Barros de Moura
authors.initials: LB
authors.lastname: Neiva
authors.affiliation: Nephrology Division, Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Edson Andrade
authors.initials: EA
authors.lastname: Pessoa
authors.affiliation: Nephrology Division, Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Fernanda Teixeira
authors.initials: FT
authors.lastname: Borges
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018374:LLC-PK1 Cells; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009336:Necrosis; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D011112:Polymyxin B / Q000493:pharmacokinetics / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D009569:Nitric Oxide; D045304:Cytochromes c; D007770:L-Lactate Dehydrogenase; D011112:Polymyxin B