Neutrophils recruited to the myocardium after acute experimental myocardial infarct generate hypochlorous acid that oxidizes cardiac myoglobin.

Myocardial inflammation following acute myocardial infarct (AMI) is associated with risk of congestive heart failure. Pro-inflammatory neutrophils were recruited to the damaged myocardium 24 h after permanent coronary ligation in rats to induce AMI as judged by the presence of immune-positive myeloperoxidase (MPO) in the tissues; MPO generates the oxidant hypochlorous acid (HOCl). Neutrophils were absent in hearts from Control (untreated) and surgical Sham. Similarly, rats exposed to 1 h coronary ligation (Ischemia) showed no neutrophil infiltrate. Concomitantly, MPO activity increased in left ventricular (LV) homogenates prepared from the AMI group and this was inhibited by paracetamol and the nitroxide TEMPO. The same LV-homogenates showed increased 3-chlorotyrosine/tyrosine ratios (biomarker for MPO-activity). Combined 2D gel/Western blot indicated cardiac myoglobin (Mb) was modified after AMI. Subsequent MALDI-TOF and LC-MS/MS analysis of isolated protein spots revealed increased Mb oxidation in hearts from the AMI group relative to Control, Sham and Ischemia groups. Peptide mass mapping revealed oxidation of Met9 and Met132 to the corresponding sulfoxides yet Cys67 remained unmodified. Therefore, neutrophil-generated HOCl can oxidize cardiac Mb after AMI and this may impact on its function within the affected myocardium: oxidized Mb maybe a useful marker of myocardial inflammation.

Selenium inhibits renal oxidation and inflammation but not acute kidney injury in an animal model of rhabdomyolysis.

UNLABELLED: Acute kidney injury (AKI) is a manifestation of rhabdomyolysis (RM). Extracellular myoglobin accumulating in the kidney after RM promotes oxidative damage, which is implicated in AKI. AIM: To test whether selenium (Se) supplementation diminishes AKI and improves renal function. RESULTS: Dietary selenite increased Se in the renal cortex, as demonstrated by X-ray fluorescence microscopy. Experimental RM-stimulated AKI as judged by increased urinary protein/creatinine, clusterin, and kidney injury molecule-1 (KIM-1), decreased creatinine clearance (CCr), increased plasma urea, and damage to renal tubules. Concentrations of cholesterylester (hydro)peroxides and F2-isoprostanes increased in plasma and renal tissues after RM, while aortic and renal cyclic guanidine monophosphate (cGMP; marker of nitric oxide (NO) bioavailability) decreased. Renal superoxide dismutase-1, phospho-P65, TNFα gene, MCP-1 protein, and the 3-chloro-tyrosine/tyrosine ratio (Cl-Tyr/Tyr; marker of neutrophil activation) all increased after RM. Dietary Se significantly decreased renal lipid oxidation, phospho-P65, TNFα gene expression, MCP-1 and Cl-Tyr/Tyr, improved NO bioavailability in aorta but not in the renal microvasculature, and inhibited proteinuria. However, CCr, plasma urea and creatinine, urinary clusterin, and histopathological assessment of AKI remained unchanged. Except for the Se++ group, renal angiotensin-receptor-1/2 gene/protein expression increased after RM with parallel increases in MEK1/2 inhibitor-sensitive MAPkinase (ERK) activity. INNOVATION: We employed synchrotron radiation to identify Se distribution in kidneys, in addition to assessing reno-protection after RM. CONCLUSION: Se treatment has some potential as a therapeutic for AKI as it inhibits oxidative damage and inflammation and decreases proteinuria, albeit histopathological changes to the kidney and some plasma and urinary markers of AKI remain unaffected after RM.

Cosupplementation with a synthetic, lipid-soluble polyphenol and vitamin C inhibits oxidative damage and improves vascular function yet does not inhibit acute renal injury in an animal model of rhabdomyolysis.

We investigated whether cosupplementation with synthetic tetra-tert-butyl bisphenol (BP) and vitamin C (Vit C) ameliorated oxidative stress and acute kidney injury (AKI) in an animal model of acute rhabdomyolysis (RM). Rats were divided into groups: Sham and Control (normal chow), and BP (receiving 0.12% w/w BP in the diet; 4 weeks) with or without Vit C (100mg/kg ascorbate in PBS ip at 72, 48, and 24h before RM induction). All animals (except the Sham) were treated with 50% v/v glycerol/PBS (6 mL/kg injected into the hind leg) to induce RM. After 24h, urine, plasma, kidneys, and aortae were harvested. Lipid oxidation (assessed as cholesteryl ester hydroperoxides and hydroxides and F(2)-isoprostanes accumulation) increased in the kidney and plasma and this was coupled with decreased aortic levels of cyclic guanylylmonophosphate (cGMP). In renal tissues, RM stimulated glutathione peroxidase (GPx)-4, superoxide dismutase (SOD)-1/2 and nuclear factor kappa-beta (NFκß) gene expression and promoted AKI as judged by formation of tubular casts, damaged epithelia, and increased urinary levels of total protein, kidney-injury molecule-1 (KIM-1), and clusterin. Supplementation with BP±Vit C inhibited the two indices of lipid oxidation, down-regulated GPx-4, SOD1/2, and NF-κß gene responses and restored aortic cGMP, yet renal dysfunction and altered kidney morphology persisted. By contrast, supplementation with Vit C alone inhibited oxidative stress and diminished cast formation and proteinuria, while other plasma and urinary markers of AKI remained elevated. These data indicate that lipid- and water-soluble antioxidants may differ in terms of their therapeutic impact on RM-induced renal dysfunction.

Phenolic antioxidants tert-butyl-bisphenol and vitamin E decrease oxidative stress and enhance vascular function in an animal model of rhabdomyolysis yet do not improve acute renal dysfunction.

Rhabdomyolysis (RM) caused by severe burn releases extracellular myoglobin (Mb) that accumulates in the kidney. Extracellular Mb is a pro-oxidant. This study tested whether supplementation with tert-butyl-bisphenol (BP) or vitamin E (Vit E, as α-tocopherol) at 0.12% w/w in the diet inhibits acute renal failure (ARF) in an animal model of RM. After RM-induction in rats, creatinine clearance decreased (p < 0.01), proteinuria increased (p < 0.001) and renal-tubule damage was detected. Accompanying ARF, biomarkers of oxidative stress (lipid oxidation and hemeoxygenase-1 (HO-1) gene and protein activity) increased in the kidney (p < 0.05). Supplemented BP or Vit E decreased lipid oxidation (p < 0.05) and HO-1 gene/activity and restored aortic cyclic guanylyl monophosphate in control animals (p < 0.001), yet ARF was unaffected. Antioxidant supplementation inhibited oxidative stress, yet was unable to ameliorate ARF in this animal model indicating that oxidative stress in kidney and vascular cells may not be causally related to renal dysfunction elicited by RM.