Role of heme oxygenase-1 in polymyxin B-induced nephrotoxicity in rats

Abstract

Polymyxin B (PMB) is a cationic polypeptide antibiotic with activity against multidrug-resistant Gram-negative bacteria. PMB-induced nephrotoxicity consists of direct toxicity to the renal tubules and the release of reactive oxygen species (ROS) with oxidative damage. This study evaluated the nephroprotective effect of heme oxygenase-1 (HO-1) against PMB-induced nephrotoxicity in rats. Adult male Wistar rats, weighing 286 ± 12 g, were treated intraperitoneally once a day for 5 days with saline, hemin (HO-1 inducer; 10 mg/kg), zinc protoporphyrin (ZnPP) (HO-1 inhibitor; 50 μmol/kg, administered before PMB on day 5), PMB (4 mg/kg), PMB plus hemin, and PMB plus ZnPP. Renal function (creatinine clearance, Jaffe method), urinary peroxides (ferrous oxidation of xylenol orange version 2 [FOX-2]), urinary thiobarbituric acid-reactive substances (TBARS), renal tissue thiols, catalase activity, and renal tissue histology were analyzed. The results showed that PMB reduced creatinine clearance (P < 0.05), with an increase in urinary peroxides and TBARS. The PMB toxicity caused a reduction in catalase activity and thiols (P < 0.05). Hemin attenuated PMB nephrotoxicity by increasing the catalase antioxidant activity (P < 0.05). The combination of PMB and ZnPP incremented the fractional interstitial area of renal tissue (P < 0.05), and acute tubular necrosis in the cortex area was also observed. This is the first study demonstrating the protective effect of HO-1 against PMB-induced nephrotoxicity.

Fig 1

Mean (±standard deviation [SD]) urinary peroxides in the saline, hemin, ZnPP, PMB, PMB plus hemin, and PMB plus ZnPP groups. #, significantly different from the saline group (P < 0.05); *, significantly different from the PMB group (P < 0.05).

Fig 2

Mean (±SD) TBARS levels in the saline, hemin, ZnPP, PMB, PMB plus hemin, and PMB plus ZnPP groups. #, significantly different from the saline group (P < 0.05); *, significantly different from the PMB group (P < 0.05).

Fig 3

Mean (±SD) thiols in the saline, hemin, ZnPP, PMB, PMB plus hemin, and PMB plus ZnPP groups. #, significantly different from the saline group (P < 0.05).

Fig 4

Mean (±SD) catalase activity in the saline, hemin, ZnPP, PMB, PMB plus hemin, and PMB plus ZnPP groups. #, significantly different from the saline group (P < 0.05); *, significantly different from the PMB group (P < 0.05).

Fig 5

Histological sections of renal tissue obtained from the different groups: saline (A), PMB (B), PMB plus ZnPP (C), and PMB plus hemin (D). Magnification, ×400.