Resveratrol improves renal microcirculation, protects the tubular epithelium, and prolongs survival in a mouse model of sepsis-induced acute kidney injury
2011; Elsevier BV; Volume: 81; Issue: 4 Linguagem: Inglês
10.1038/ki.2011.347
ISSN1523-1755
AutoresJoseph H. Holthoff, Zhen Wang, Kathryn A. Seely, Neriman Gökden, Philip R. Mayeux,
Tópico(s)Anesthesia and Neurotoxicity Research
ResumoThe mortality rate of patients who develop acute kidney injury during sepsis nearly doubles. The effectiveness of therapy is hampered because it is usually initiated only after the onset of symptoms. As renal microvascular failure during sepsis is correlated with the generation of reactive nitrogen species, the therapeutic potential of resveratrol, a polyphenol vasodilator that is also capable of scavenging reactive nitrogen species, was investigated using the cecal ligation and puncture (CLP) murine model of sepsis-induced acute kidney injury. Resveratrol when given at 5.5h following CLP reversed the decline in cortical capillary perfusion, assessed by intravital microscopy, at 6h in a dose-dependent manner. Resveratrol produced the greatest improvement in capillary perfusion and increased renal blood flow and the glomerular filtration rate without raising systemic pressure. A single dose at 6h after CLP was unable to improve renal microcirculation assessed at 18h; however, a second dose at 12h significantly improved microcirculation and decreased the levels of reactive nitrogen species in tubules, while improving renal function. Moreover, resveratrol given at 6, 12, and 18h significantly improved survival. Hence, resveratrol may have a dual mechanism of action to restore the renal microcirculation and scavenge reactive nitrogen species, thus protecting the tubular epithelium even when administered after the onset of sepsis. The mortality rate of patients who develop acute kidney injury during sepsis nearly doubles. The effectiveness of therapy is hampered because it is usually initiated only after the onset of symptoms. As renal microvascular failure during sepsis is correlated with the generation of reactive nitrogen species, the therapeutic potential of resveratrol, a polyphenol vasodilator that is also capable of scavenging reactive nitrogen species, was investigated using the cecal ligation and puncture (CLP) murine model of sepsis-induced acute kidney injury. Resveratrol when given at 5.5h following CLP reversed the decline in cortical capillary perfusion, assessed by intravital microscopy, at 6h in a dose-dependent manner. Resveratrol produced the greatest improvement in capillary perfusion and increased renal blood flow and the glomerular filtration rate without raising systemic pressure. A single dose at 6h after CLP was unable to improve renal microcirculation assessed at 18h; however, a second dose at 12h significantly improved microcirculation and decreased the levels of reactive nitrogen species in tubules, while improving renal function. Moreover, resveratrol given at 6, 12, and 18h significantly improved survival. Hence, resveratrol may have a dual mechanism of action to restore the renal microcirculation and scavenge reactive nitrogen species, thus protecting the tubular epithelium even when administered after the onset of sepsis. Sepsis is a disseminated inflammatory response elicited by a microbial infection1.Lee W.L. Slutsky A.S. Sepsis and endothelial permeability.N Engl J Med. 2010; 363: 689-691Crossref PubMed Scopus (362) Google Scholar and is the major cause of death among critically ill patients.2.Hotchkiss R.S. Karl I.E. The pathophysiology and treatment of sepsis.N Engl J Med. 2003; 348: 138-150Crossref PubMed Scopus (3207) Google Scholar,3.Angus D.C. Linde-Zwirble W.T. 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Sepsis and endothelial permeability.N Engl J Med. 2010; 363: 689-691Crossref PubMed Scopus (362) Google Scholar Early goal-directed therapy, consisting of fluid resuscitation and supportive treatment to protect organ perfusion, can improve survival;5.Rivers E.P. Coba V. Whitmill M. Early goal-directed therapy in severe sepsis and septic shock: a contemporary review of the literature.Curr Opin Anesthesiol. 2008; 21: 128-140Crossref PubMed Scopus (144) Google Scholar however, mortality rates still approach 30% even among adequately resuscitated patients.6.Lundy D.J. Trzeciak S. Microcirculatory dysfunction in sepsis.Crit Care Clin. 2009; 25 (viii): 721-731Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar,7.Otero R.M. Nguyen H.B. 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Microvascular dysfunction as a cause of organ dysfunction in severe sepsis.Crit Care. 2005; 9: S9-S12Crossref PubMed Scopus (140) Google Scholar Development of acute kidney injury (AKI) is common during severe sepsis and more than doubles the mortality rate to nearly 75%.10.Heemskerk S. Masereeuw R. Russel F.G. et al.Selective iNOS inhibition for the treatment of sepsis-induced acute kidney injury.Nat Rev Nephrol. 2009; 5: 629-640Crossref PubMed Scopus (124) Google Scholar Studies in rodent models have shown that the renal microcirculation is compromised during the development of sepsis.11.Wu L. Tiwari M.M. Messer K.J. et al.Peritubular capillary dysfunction and renal tubular epithelial cell stress following lipopolysaccharide administration in mice.Am J Physiol Renal Physiol. 2007; 292: F261-F268Crossref PubMed Scopus (109) Google Scholar, 12.Wu L. Gokden N. Mayeux P.R. 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Burns S.T. et al.Hemodynamic changes in the kidney in a pediatric rat model of sepsis-induced acute kidney injury.Am J Physiol Renal Physiol. 2011; 301: F209-F217Crossref PubMed Scopus (66) Google Scholar Thus, there is a pressing need for the development of novel therapeutic approaches to treat sepsis-induced AKI, which can restore perfusion of the renal microcirculation even when initiated after the onset of sepsis.6.Lundy D.J. Trzeciak S. Microcirculatory dysfunction in sepsis.Crit Care Clin. 2009; 25 (viii): 721-731Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar, 16.Trzeciak S. Cinel I. Phillip Dellinger R. et al.Resuscitating the microcirculation in sepsis: the central role of nitric oxide, emerging concepts for novel therapies, and challenges for clinical trials.Acad Emerg Med. 2008; 15: 399-413Crossref PubMed Scopus (168) Google Scholar, 17.Hollenberg S.M. Think locally: evaluation of the microcirculation in sepsis.Intensive Care Med. 2010; 36: 1807-1809Crossref PubMed Scopus (13) Google Scholar Hallmarks of sepsis include excessive generation of nitric oxide (NO),10.Heemskerk S. Masereeuw R. Russel F.G. et al.Selective iNOS inhibition for the treatment of sepsis-induced acute kidney injury.Nat Rev Nephrol. 2009; 5: 629-640Crossref PubMed Scopus (124) Google Scholar endothelial injury, and a loss of vascular reactivity,6.Lundy D.J. Trzeciak S. Microcirculatory dysfunction in sepsis.Crit Care Clin. 2009; 25 (viii): 721-731Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar,18.Zanotti-Cavazzoni S.L. Hollenberg S.M. Cardiac dysfunction in severe sepsis and septic shock.Curr Opin Crit Care. 2009; 15: 392-397Crossref PubMed Scopus (243) Google Scholar resulting in areas of local microcirculatory hypoperfusion6.Lundy D.J. Trzeciak S. Microcirculatory dysfunction in sepsis.Crit Care Clin. 2009; 25 (viii): 721-731Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar,17.Hollenberg S.M. Think locally: evaluation of the microcirculation in sepsis.Intensive Care Med. 2010; 36: 1807-1809Crossref PubMed Scopus (13) Google Scholar and areas of tissue hypoxia. This leads to a peritubular pro-oxidant microenvironment favoring the generation of reactive oxygen and reactive nitrogen species (RNS).13.Wang Z. Herzog C. Kaushal G.P. et al.Actinonin, a meprin A inhibitor, protects the renal microcirculation during sepsis.Shock. 2011; 35: 141-147Crossref PubMed Scopus (36) Google Scholar, 19.Walker L.M. York J.L. Imam S.Z. et al.Oxidative stress and reactive nitrogen species generation during renal ischemia.Toxicol Sci. 2001; 63: 143-148Crossref PubMed Scopus (98) Google Scholar, 20.Wu L. Mayeux P.R. Effects of the inducible nitric oxide synthase inhibitor L-N6-(1-iminoethyl)-lysine on microcirculation and reactive nitrogen species generation in the kidney following lipopolysaccharide administration in mice.J Pharmacol Exp Ther. 2007; 320: 1061-1067Crossref PubMed Scopus (45) Google Scholar The reaction of NO with superoxide generates peroxynitrite, a powerful oxidizing RNS that causes protein nitration, DNA damage, and mitochondrial dysfunction, all of which have been suggested to be critical to the progression of AKI during sepsis.10.Heemskerk S. Masereeuw R. Russel F.G. et al.Selective iNOS inhibition for the treatment of sepsis-induced acute kidney injury.Nat Rev Nephrol. 2009; 5: 629-640Crossref PubMed Scopus (124) Google Scholar, 12.Wu L. Gokden N. Mayeux P.R. Evidence for the role of reactive nitrogen species in polymicrobial sepsis-induced renal peritubular capillary dysfunction and tubular injury.J Am Soc Nephrol. 2007; 18: 1807-1815Crossref PubMed Scopus (113) Google Scholar, 13.Wang Z. Herzog C. Kaushal G.P. et al.Actinonin, a meprin A inhibitor, protects the renal microcirculation during sepsis.Shock. 2011; 35: 141-147Crossref PubMed Scopus (36) Google Scholar, 21.Guo R. Wang Y. Minto A.W. et al.Acute renal failure in endotoxemia is dependent on caspase activation.J Am Soc Nephrol. 2004; 15: 3093-3102Crossref PubMed Scopus (114) Google Scholar Thus, RNS generation occurring later in the progression of sepsis could be a suitable therapeutic target for agents administered after the onset of sepsis,12.Wu L. Gokden N. Mayeux P.R. Evidence for the role of reactive nitrogen species in polymicrobial sepsis-induced renal peritubular capillary dysfunction and tubular injury.J Am Soc Nephrol. 2007; 18: 1807-1815Crossref PubMed Scopus (113) Google Scholar,22.Miyaji T. Hu X. Yuen P.S. et al.Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice.Kidney Int. 2003; 64: 1620-1631Abstract Full Text Full Text PDF PubMed Scopus (231) Google Scholar but this has not yet been directly studied. Resveratrol (RES), a polyphenolic nutraceutical with vasodilatory and antioxidant activities, has been shown to be protective in various disease models,23.Baur J.A. Sinclair D.A. Therapeutic potential of resveratrol: the in vivo evidence.Nat Rev Drug Discov. 2006; 5: 493-506Crossref PubMed Scopus (3214) Google Scholar,24.Gresele P. Cerletti C. Guglielmini G. et al.Effects of resveratrol and other wine polyphenols on vascular function: an update.J Nutr Biochem. 2011; 22: 201-211Abstract Full Text Full Text PDF PubMed Scopus (140) Google Scholar including septic rats, when administered before or at the very onset of sepsis.25.Kolgazi M. Sener G. Cetinel S. et al.Resveratrol reduces renal and lung injury caused by sepsis in rats.J Surg Res. 2006; 134: 315-321Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar,26.Sebai H. Ben-Attia M. Sani M. et al.Protective effect of resveratrol on acute endotoxemia-induced nephrotoxicity in rat through nitric oxide independent mechanism.Free Radic Res. 2008; 42: 913-920Crossref PubMed Scopus (32) Google Scholar We recently showed that RES is a potent scavenger of peroxynitrite and can protect tubular epithelial cells from the damaging effects of peroxynitrite in vitro.27.Holthoff J.H. Woodling K.A. Doerge D.R. et al.Resveratrol, a dietary polyphenolic phytoalexin, is a functional scavenger of peroxynitrite.Biochem Pharmacol. 2010; 80: 1260-1265Crossref PubMed Scopus (90) Google Scholar To investigate the therapeutic potential of RES, we studied its effects on renal macro- and microcirculation and tubular epithelial RNS generation during sepsis. In the first series of experiments, we determined the acute dose effects of RES on the peritubular microcirculation, as well as its acute effects on renal blood flow (RBF) and glomerular filtration rate (GFR). Thereafter, to more closely mimic the clinical setting,28.Russell J.A. Management of sepsis.N Engl J Med. 2006; 355: 1699-1713Crossref PubMed Scopus (897) Google Scholar we used a delayed treatment regimen initiated after the onset of septic shock to examine the effects of RES on peritubular capillary failure, RNS generation, renal function, and survival. A hallmark of both clinical sepsis and experimental animal models of sepsis is severe microvascular dysfunction.6.Lundy D.J. Trzeciak S. Microcirculatory dysfunction in sepsis.Crit Care Clin. 2009; 25 (viii): 721-731Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar,29.Cepinskas G. Wilson J.X. Inflammatory response in microvascular endothelium in sepsis: role of oxidants.J Clin Biochem Nutr. 2008; 42: 175-184Crossref PubMed Scopus (73) Google Scholar Using intravital video microscopy (IVVM), we categorized the cortical distribution of peritubular capillary perfusion as continuous, intermittent, or no flow. At 6h, sham control mice had a high percentage of continuously perfused renal cortical capillaries (79±2%) and only a small percentage of capillaries with no flow (Figure 1). In contrast, at 6h post cecal ligation and puncture (CLP), the percentage of capillaries with continuous perfusion was reduced to 34±5% and the percentage of capillaries with no perfusion was increased to 45±5%. The acute effects of RES on the renal microcirculation were tested at doses of 3, 10, 30, and 100mg/kg (intraperitoneal, i.p.) administered at 5.5h post sham or CLP surgery. Capillary perfusion was then assessed at 6h. Although the highest dose of RES tested (100mg/kg) caused no obvious signs of toxicity in sham mice, this dose was lethal in CLP mice within 30min (100% mortality, n=3). Therefore, this dose was omitted from all subsequent studies. These categorical data were analyzed using the Hotelling's T2-test (see Materials and Methods) to compare the distribution between groups. Doses of 10 and 30mg/kg reversed the decline in capillary perfusion in CLP mice (Figure 1a). As a control, RES (30mg/kg, i.p.) was administered to sham mice and had no effect on capillary perfusion (data not shown). As categorical perfusion data do not address nutritive capillary flow, mean red blood cell (RBC) velocity was measured in continually flowing capillaries from the same videos analyzed in Figure 1a. At 6h, the measured mean RBC velocity in sham mice was 374±20μm/s. CLP caused a significant reduction in mean RBC velocity compared with sham (126±16μm/s; P<0.05). Resveratrol produced a bell-shaped dose–response curve for restoring RBC velocity (Figure 1b), with 10mg/kg being the most efficacious dose tested. MAP in CLP decreased from 111±7mmHg before surgery to 77±7mmHg (P<0.05) at 6h post surgery, whereas MAP in sham did not change significantly (115±7 vs. 111±6mmHg). Resveratrol at doses of 3, 10, or 30mg/kg administered at 5.5h did not affect MAP at 6h in CLP, nor did RES at a dose of 30mg/kg affect MAP in sham (Figure 2a). HR in CLP decreased from 558±49b.p.m. before surgery to 331±18b.p.m. (P<0.05) at 6h, whereas HR in sham did not change significantly (629±27 vs. 561±4b.p.m.). Resveratrol at doses of 3, 10, or 30mg/kg administered at 5.5h did not affect HR at 6h in CLP, but 30mg/kg did increase HR slightly in sham (P<0.05; Figure 2b). These data suggested that the increase in microcirculatory perfusion in CLP mice observed following RES administration was not the result of an increase in MAP or HR. As RBF is a major determinant of renal microcirculatory perfusion, the effects of RES on RBF were determined. At 5.5h after CLP or sham surgery, a baseline measurement of RBF was obtained and RES (10mg/kg) or vehicle was administered via the penile vein. A second measurement of RBF was obtained at 6h. At 5.5h, RBF was significantly lower in CLP mice compared with sham (1.1±0.2 versus 3.4±0.3ml/min per g, respectively; P<0.05; Figure 3a). At 30min post treatment, vehicle had no effect on RBF in CLP mice and RES had no effect on RBF in sham mice. In contrast, RES significantly raised RBF to 2.6±0.6ml/min per g (P<0.05 compared with CLP), a value not different from that seen in sham. To assess the acute effects of RES administration on renal function, GFR was measured in conscious mice beginning at 6h after CLP or sham surgery. CLP mice showed a significantly lower GFR at 6h compared with sham (0.36±0.04 versus 1.03±0.07ml/min per g; P<0.05). Administration of RES 30min before GFR measurement in CLP mice (Figure 3b) resulted in an acute improvement in GFR (0.54±0.04ml/min per g; P<0.05 compared with CLP). At 18h following CLP, capillary perfusion and mean RBC velocity were still low relative to sham (Figure 4). A single dose of RES (10mg/kg, i.p.) administered at 6h was unable to maintain perfusion through 18h. However, a second dose administered at 12h prevented the change in the distribution of cortical perfusion and the decline in RBC velocity (Figure 4a and b). As oxidation of dihydrorhodamine-1,2,3 is not absolutely selective for the RNS peroxynitrite,30.Crow J.P. Peroxynitrite scavenging by metalloporphyrins and thiolates.Free Rad Biol Med. 2000; 28: 1487-1494Crossref PubMed Scopus (79) Google Scholar,31.Gomes A. Fernandes E. Lima J.L. Use of fluorescence probes for detection of reactive nitrogen species: a review.J Fluoresc. 2006; 16: 119-139Crossref PubMed Scopus (140) Google Scholar two complementary approaches were used to detect the generation of peroxynitrite: (1) oxidation of dihydrorhodamine-1,2,3 to rhodamine and (2) detection of immunoreactive nitrotyrosine–protein adducts.32.Beckman J.S. Oxidative damage and tyrosine nitration from peroxynitrite.Chem Res Tox. 1996; 9: 836-844Crossref PubMed Scopus (913) Google Scholar We previously reported that rhodamine fluorescence appears in tubules bordered by capillaries with no flow, and that both rhodamine fluorescence and nitrotyrosine–protein adducts appear in the vacuoles of injured tubules.12.Wu L. Gokden N. Mayeux P.R. Evidence for the role of reactive nitrogen species in polymicrobial sepsis-induced renal peritubular capillary dysfunction and tubular injury.J Am Soc Nephrol. 2007; 18: 1807-1815Crossref PubMed Scopus (113) Google Scholar Representative pseudocolored images of rhodamine fluorescence from the sham, CLP, and CLP+RES (two doses) groups were captured from the cortices of live mice using IVVM and are presented in Figure 5a–c, respectively, along with the quantification of pixel intensity in Figure 5d. Only weak rhodamine fluorescence was observed in sham at 18h (Figure 5a), but rhodamine fluorescence was increased in tubules from CLP mice (Figure 5b). A single dose of RES (10mg/kg) administered at 6h significantly reduced rhodamine fluorescence in CLP mice, as did two doses (Figure 5d). Representative images of nitrotyrosine staining from the sham, CLP, and CLP+RES (two doses) groups are presented in Figure 5e–g, respectively. Sham tissue displayed only weak staining for nitrotyrosine–protein adducts. In contrast, at 18h after CLP, nitrotyrosine staining was intense in renal tubules but not in glomeruli. No staining was observed in the nonspecific binding control (not shown), where the anti-nitrotyrosine antibody was preincubated with 10mmol/l nitrotyrosine before use. Two doses of RES blocked the formation of nitrotyrosine–protein adducts. Both independent methods of detection (ongoing generation with rhodamine and cumulative generation with nitrotyrosine immunohistochemistry) indicated that RES reduced renal levels of RNS. The systemic inflammatory response following CLP is associated with early release of cytokines such as tumor necrosis factor-α22.Miyaji T. Hu X. Yuen P.S. et al.Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice.Kidney Int. 2003; 64: 1620-1631Abstract Full Text Full Text PDF PubMed Scopus (231) Google Scholar,33.Wang Z. Rabb H. Haq M. et al.A possible molecular basis of natriuresis during ischemic-reperfusion injury in the kidney.J Am Soc Nephrol. 1998; 9: 605-613PubMed Google Scholar and increased generation of NO.13.Wang Z. Herzog C. Kaushal G.P. et al.Actinonin, a meprin A inhibitor, protects the renal microcirculation during sepsis.Shock. 2011; 35: 141-147Crossref PubMed Scopus (36) Google Scholar To help address whether RES decreased RNS levels by decreasing NO generation, the effects of RES on serum NO levels were determined by measuring serum nitrate+nitrite concentration. At 18h, levels in CLP were significantly higher than that in sham (166±16 versus 60±5μmol/l; P 0.05 compared with CLP). At 18h, morphological changes in the CLP group were characterized by mild brush border loss, tubular degeneration, and vacuolization in the early segments of proximal tubules (Figure 6b). The two-dose RES treatment regimen reduced the morphological damage and the tubular injury score (Figure 6c and d). As RES was shown to improve renal microcirculation, RNS generation, and tubular morphology, we investigated the ability of RES to protect against the development of AKI. At 18h post CLP, two clinically used markers of AKI, blood urea nitrogen, and creatinine, were increased in CLP mice (Figure 7a and b). Although the single dose of RES (10mg/kg) administered at 6h reduced only serum creatinine levels (data not shown), two doses of RES administered at 6 and 12h post CLP significantly reduced both markers (Figure 7a and b). As serum creatinine is no longer considered a reliable marker of GFR and renal function in mice,34.Doi K. Yuen P.S. Eisner C. et al.Reduced production of creatinine limits its use as marker of kidney injury in sepsis.J Am Soc Nephrol. 2009; 20: 1217-1221Crossref PubMed Scopus (287) Google Scholar GFR and RBF were measured at 18h. CLP mice showed a significant reduction in both GFR and RBF compared with sham at 18h (Figure 7c and d). Administration of two doses of RES significantly improved (doubled) GFR from 0.20±0.06ml/min per g in CLP to 0.41±0.05ml/min per g in CLP+RES (P<0.05) and significantly improved (doubled) RBF from 1.1±0.1ml/min per g in CLP to 2.4±0.1ml/min per g in CLP+RES (P<0.05). However, RES did not restore RBF or GFR to sham levels. The ability of RES to improve renal microcirculation and restore renal function led us to investigate the potential of RES to increase survival following CLP using a clinically relevant dosing protocol starting 6h after the induction of sepsis (CLP). Two groups of mice were subjected to CLP. Beginning at 6h, one group received vehicle at 6, 12, and 18h, whereas the other group received RES (10mg/kg, i.p.) at 6, 12, and 18h. Using a defined criteria of impending mortality (core temperature of <28°C35.Warn P.A. Brampton M.W. Sharp A. et al.Infrared body temperature measurement of mice as an early predictor of death in experimental fungal infections.Lab Anim. 2003; 37: 126-131Crossref PubMed Scopus (66) Google Scholar), RES significantly improved survival (Figure 8; P<0.001 using the Mantel–Cox log rank test). Microvascular dysfunction is a strong predictor of death among septic patients.29.Cepinskas G. Wilson J.X. Inflammatory response in microvascular endothelium in sepsis: role of oxidants.J Clin Biochem Nutr. 2008; 42: 175-184Crossref PubMed Scopus (73) Google Scholar In both lipopolysaccharide20.Wu L. Mayeux P.R. Effects of the inducible nitric oxide synthase inhibitor L-N6-(1-iminoethyl)-lysine on microcirculation and reactive nitrogen species generation in the kidney following lipopolysaccharide administration in mice.J Pharmacol Exp Ther. 2007; 320: 1061-1067Crossref PubMed Scopus (45) Google Scholar,36.Tiwari M.M. Brock R.W. Kaushal G.P. et al.Disruption of renal peritubular blood flow in lipopolysaccharide-induced renal failure: role of nitric oxide and caspases.Am J Physiol Renal Physiol. 2005; 289: F1324-F1332Crossref PubMed Scopus (90) Google Scholar and CLP12.Wu L. Gokden N. Mayeux P.R. Evidence for the role of reactive nitrogen species in polymicrobial sepsis-induced renal peritubular capillary dysfunction and tubular injury.J Am Soc Nephrol. 2007; 18: 1807-1815Crossref PubMed Scopus (113) Google Scholar, 13.Wang Z. Herzog C. Kaushal G.P. et al.Actinonin, a meprin A inhibitor, protects the renal microcirculation during sepsis.Shock. 2011; 35: 141-147Crossref PubMed Scopus (36) Google Scholar, 14.Yasuda H. Yuen P.S. Hu X. et al.Simvastatin improves sepsis-induced mortality and acute kidney injury via renal vascular effects.Kidney Int. 2006; 69: 1535-1542Abstract Full Text Full Text PDF PubMed Scopus (177) Google Scholar models of sepsis-induced AKI, peritubular capillary hypoperfusion occurs rapidly and is associated with subsequent generation of peroxynitrite in the renal epithelium. As we recently showed that RES is a potent scavenger of peroxynitrite and can protect tubular epithelial cells from the damaging effects of peroxynitrite in vitro,27.Holthoff J.H. Woodling K.A. Doerge D.R. et al.Resveratrol, a dietary polyphenolic phytoalexin, is a functional scavenger of peroxynitrite.Biochem Pharmacol. 2010; 80: 1260-1265Crossref PubMed Scopus (90) Google Scholar we studied the therapeutic potential of RES using a murine model of sepsis and a clinically relevant treatment regimen. It is becoming increasingly clear that early goal-directed therapy has the greatest chance of improving the outcome in patients with severe sepsis.37.Dudley C. Maximizing renal preservation in acute renal failure.BJU Int. 2004; 94: 1202-1206Crossref PubMed Scopus (6) Google Scholar,38.Nguyen H.B. Corbett S.W. Menes K. et al.Early goal-directed therapy, corticosteroid, and recombinant human activated protein C for the treatment of severe sepsis and septic shock in the emergency department.Acad Emerg Med. 2006; 13: 109-113Crossref PubMed Google Scholar Moreover, targeting the microcirculation to preserve/restore perfusion would not only lessen injury but also promote organ recovery.39.Ince C. The microcirculation is the motor of sepsis.Crit Care. 2005; 9: S13-S19Crossref PubMed Scopus (603) Google Scholar,40.Le Dorze M. Legrand M. Payen D. et al.The role of the microcirculation in acute kidney injury.Curr Opin Crit Care. 2009; 15: 503-508Crossref PubMed Scopus (130) Google Scholar Unfortunately, effective therapy in the septic patient is hampered because therapy usually begun only after the onset of symptoms (i.e., systemic inflammatory response syndrome).28.Russell J.A. Management of sepsis.N Engl J Med. 2006; 355: 1699-1713Crossref PubMed Scopus (897) Google Scholar In this study, we examined the acute effects of RES on CLP-induced AKI using a clinically relevant course of therapy that began after the development of septic shock and the decline in renal microcirculatory perfusion. We chose to examine the effects of RES at 6h post CLP, a time when systemic inflammation had already begun22.Miyaji T. Hu X. Yuen P.S. et al.Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice.Kidney Int. 2003; 64: 1620-1631Abstract Full Text Full Text PDF PubMed Scopus (231) Google Scholar and peritubular capillary perfusion was severely reduced.13.Wang Z. Herzog C. Kaushal G.P. et al.Actinonin, a meprin A inhibitor, protects the renal microcirculation during sepsis.Shock. 2011; 35: 141-147Crossref PubMed Scopus (36) Google Scholar Within 30min of administration, RES restored both measures of peritubular capillary perfusion: categorical perfusion (an index of overall perfusion) and RBC velocity. Surprisingly, in CLP mice, RES exhibited a bell-shaped dose–response curve. Doses higher than 10mg/kg were less effective in restoring velocity or, in the case of the 100mg/kg dose, lethal within 30min. It is important to note that RES was administered i.p. rather than orally, where extremely high oral doses exhibit little signs of toxicity, presumably because of the low bioavailability of oral RES.41.Walle T. Hsieh F. DeLegge M.H. et al.High absorption but very low bioavailability of oral resveratrol in huma
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