Reversal of Experimental Myoglobinuric Acute Renal Failure in Rats by Quercetin, a Bioflavonoid

Preclinical evidence of reno-protective effect of quercetin on acute kidney injury: a meta-analysis of animal studies

Objective: This study evaluated the reno-protective effects of quercetin in animal models of acute kidney injury (AKI). Methods: We conducted a systematic search of literature published before April 2023 in PubMed, Web of Science, and EMBASE databases. Methodological quality was assessed by SYRCLE's RoB tool. Funnel plot, Egger's test, and Begg's test were used to determine publication bias. Results: A total of 19 studies with 288 animals were included in this meta-analysis. The methodology quality scores of the included studies ranged from 4 to 7. The results indicated that quercetin reduced blood urea nitrogen (SMD = -4.78; 95% CI: 6.45, -3.12; p < 0.01; I2 = 84%) and serum creatinine (SMD: 2.73, 95% CI: 3.66, -1.80; p < 0.01; I2 = 80%) in AKI models. The result of sensitivity analysis was stable, while the results of funnel plot indicated asymmetric. In addition, we further analyzed inflammatory cytokines, oxidative stress levels, and kidney injury scores, and found that quercetin treatment had antioxidant and anti-inflammatory effects and improved kidney injury scores in animal models of AKI. Conclusion: Quercetin exhibited a promising reno-protective effect in AKI animal models. Systematic Review Registration: PROSPERO (CRD42023433333).

Mini Review of Biochemical Basis, Diagnosis and Management of Crush Syndrome

Crush syndrome (CS) is a metabolic disorder whose victims are individuals suffered from natural disasters such as earthquake or man-made conflicts. CS complications include acute kidney injury and cardiac arrhythmia that collectively end with death if untreated immediately. These complications are accounted for the liberation of damaged muscle tissues contents, primarily myoglobin and potassium. The present mini review discusses the biochemical basis of the development of CS. In addition, diagnosis and management and the application of novel experimental therapeutics of CS are also highlighted.

Umbelliferone attenuates glycerol-induced myoglobinuric acute kidney injury through peroxisome proliferator-activated receptor-γ agonism in rats

Rhabdomyolysis is a clinical syndrome caused by damage to skeletal muscle, which consequently releases breakdown products into circulation and causes acute kidney injury (AKI) in humans. Intramuscular injection of glycerol mimics rhabdomyolysis and associated AKI. In this study, we explored the role of umbelliferone against glycerol-induced AKI in rats. Kidney function was assessed by measuring serum creatinine, urea, electrolytes, and microproteinuria. Renal oxidative stress was quantified using thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione assay. Renal histological changes were determined using periodic acid Schiff and hematoxylin-eosin staining, and immunohistology of apoptotic markers (Bax, Bcl-2) was done. Serum creatine kinase was quantified to assess glycerol-induced muscle damage. Umbelliferone attenuated glycerol-induced change in biochemical parameters, oxidative stress, histological alterations, and renal apoptosis. Pretreatment with bisphenol A diglycidyl ether, a peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist, attenuated umbelliferone-mediated protection. It is concluded that umbelliferone attenuates glycerol-induced AKI possibly through PPAR-γ agonism in rats.

N-(2-hydroxyphenyl)acetamide and its gold nanoparticle conjugation prevent glycerol-induced acute kidney injury by attenuating inflammation and oxidative injury in mice

The protective activity of N-(2-hydroxyphenyl)acetamide (NA-2) and NA-2-coated gold nanoparticles (NA-2-AuNPs) in glycerol-treated model of acute kidney injury (AKI) in mice was investigated. NA-2 (50 mg/kg) and NA-2-AuNPs (30 mg/kg) were given to the animals for four days followed by 24-h water deprivation and injection of 50% glycerol (10 ml/kg im). The animals were sacrificed on the next day. Blood and kidneys were collected for biochemical investigations (urea and creatinine), histological studies (hematoxylin and eosin; and periodic acid-Schiff staining), immunohistochemistry (actin and cyclooxygenase-2, Cox-2), and real-time RT-PCR (inducible nitric oxide synthase, iNOS; nuclear factor-κB p50, NFκB; hemeoxygenase-1, HO-1; and kidney injury molecule-1, Kim-1). NA-2 protected renal tubular necrosis and inflammation, though the result of NA-2-AuNPs was better than compound alone and it also exhibited the activity at far less dose. The test compound and its gold nano-formulation decreased the levels of serum urea and creatinine level in the treated animals. Both NA-2 and NA-2-AuNPs also conserved actin cytoskeleton, and lowered COX-2 protein expression. Moreover, the mRNA expressions of iNOS and NFkB p50 were down-regulated, and HO-1 and Kim-1 genes were up-regulated. We conclude that NA-2 and NA-2-AuNPs ameliorates kidney inflammation and injury in glycerol-induced AKI animal model via anti-oxidant and anti-inflammatory mechanisms which make it a suitable candidate for further studies. We believe that these findings will contribute in the understanding of the mechanism of action of paracetamol-like drugs and can be considered for clinical research for the prevention of AKI.

Quercetin and iron metabolism: What we know and what we need to know

Iron is a life-supporting micronutrient that is required in the human diet, and is essential for maintaining physiological homeostasis. Properly harnessing a redox-active metal such as iron is a great challenge for cells and organisms because an excess of highly reactive iron catalyzes the formation of reactive oxygen species and can lead to cell and tissue damage. Quercetin is a typical flavonoid that is commonly found in fruits and vegetables and has versatile biological effects. From a classical viewpoint, owing to its unique chemical characteristics, quercetin has long been associated with iron metabolism only in the context of its iron-chelating and ROS-scavenging activities. However, within the field of human iron biology, expanding concepts of the roles of quercetin are flourishing, and great strides are being made in understanding the interactions between quercetin and iron. This progress highlights the varied roles of quercetin in iron metabolism, which involve much more than iron chelation alone. A review of these studies provides an ideal context to summarize recent progress and discuss compelling evidence for therapeutic opportunities that could arise from a better understanding of the underlying mechanisms.

Chronic administration of quercetin prevent spatial learning and memory deficits provoked by chronic stress in rats

There are several reports that cognitive impairment is observed in stress related disorders and chronic stress impairs learning and memory. However, very few studies have looked into the possible ways of preventing this stress-induced deficit. This research study was conducted to evaluate the effects of quercetin, a natural flavonoid, with strong antioxidant and free radical scavenger properties, on chronic stress induced learning and memory deficits and oxidative stress in hippocampus. For chronic stress, rats were restrained daily for 6h/day (from 9:00 to 15:00) for 21 days in well-ventilated plexiglass tubes without access to food and water. The animals were injected with quercetin or vehicle 60 min before restraint stress over a period of 21 days. Then, rats trained with six trials per day for 6 consecutive days in the water maze. On day 28, a probe test was done to measure memory retention. In addition, oxidative stress markers in the hippocampus were evaluated. Results of this study demonstrated that chronic stress exposure rats exhibited higher escape latency during training trials and reduced time spent in target quadrant, higher escape location latency and average proximity in probe trial test. Quercetin (50mg/kg) treatment during restraint stress (21 days) markedly decreased escape latency and increased time spent in target quadrant during Morris water maze task. In comparison to vehicle treated group, chronic-stress group had significantly higher malondialdehyde (MDA) levels, significantly higher superoxide dismutase (SOD) activity and significantly lower glutathione peroxidase (GPx) activity in the hippocampus. Quercetin treatment caused a significant decrease in the hippocampus MDA levels and improves SOD and GPx activities in stressed animals. Finally, quercetin significantly decreased plasma corticosterone levels in stressed animals. Based on results of this study, chronic stress has detrimental effects on learning and memory and quercetin treatment can prevent from oxidative stress and impairment of learning and memory induced by chronic stress.

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

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.

Quercetin protects against the Aβ(25-35)-induced amnesic injury: involvement of inactivation of rage-mediated pathway and conservation of the NVU

Quercetin has demonstrated protective effects against Aβ-induced toxicity on both neurons and endothelial cells. However, whether or not quercetin has an effect on the neurovascular coupling is unclear. In the present study, we aim to investigate the anti-amnesic effects of quercetin and to explore the underlying mechanisms. Aβ(25-35) (10 nmol) was administrated to mice i.c.v. Quercetin was administrated orally for 8 days after injection. Learning and memory behaviors were evaluated by measuring spontaneous alternation in Morris Water Maze test and the step-through positive avoidance test. The regional cerebral blood flow was monitored before the Aβ(25-35) injection and on seven consecutive days after injection. Mice were sacrificed and cerebral cortices were isolated on the last day. The effects of quercetin on the neurovascular unit (NVU) integrity, microvascular function and cholinergic neuronal changes, and the modification of signaling pathways were tested. Our results demonstrate that quercetin treatment for Aβ(25-35)-induced amnesic mice improved the learning and memory capabilities and conferred robust neurovascular coupling protection, involving maintenance of the NVU integrity, reduction of neurovascular oxidation, modulation of microvascular function, improvement of cholinergic system, and regulation of neurovascular RAGE signaling pathway and ERK/CREB/BDNF pathway. In conclusion, in Aβ(25-35)-induced amnesic mice, optimal doses of quercetin administration were beneficial. Quercetin protected the NVU likely through reduction of oxidative damage, inactivation of RAGE-mediated pathway and preservation of cholinergic neurons, offering an alternative medication for Alzheimer's disease.

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 (NFκβ) 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-κβ 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.

Rhabdomyolysis and acute renal failure in severely burned patients

Rhabdomyolysis (RML) is a precarious complication in severely burned patients and the principal treatment goal is prevention of acute renal failure (ARF). This 10-year retrospective study analyses the causes for RML in severely burned patients and evaluates treatment algorithms. Eight of 714 patients (1%) were diagnosed with RML. Percentage TBSA burn was 25 ± 13%. The mean abbreviated burn severity index score (ABSI) was 9 ± 2. ARF was found in 75% (6/8) of the patients. Serum myoglobin (MB) was reduced by 41 ± 16% after 24-h treatment by solitary volume repletion (VR) and by 44 ± 20% through VR+continuous veno-venous hemodiafiltration (CVVHDF). Mortality was 50% (4/8). Peak mean CPK-levels were more than two and MB-levels more than four times higher in non-survivors than in survivors. Burns associated with RML result in poor survival. VR and CVVHDF are effective measures in treating RML. CVVHDF is effective in removing MB when using high flux filter membranes. Early CVVHDF (within 24h of diagnosis) with high-cut off membranes could reduce the risk of ARF and mortality.

N-acetylcysteine attenuates glycerol-induced acute kidney injury by regulating MAPKs and Bcl-2 family proteins

BACKGROUND

Rhabdomyolysis-induced acute kidney injury (AKI) accounts for about 10 to 40% of all cases of AKI. It is known that N-acetylcysteine (NAC) is effective in various experimental renal injury models; however, little information is available about the rat model of glycerol-induced rhabdomyolysis. In this study, we hypothesize that NAC plays a renoprotective role via the anti-apoptotic pathway.

METHODS

Male Sprague-Dawley rats were divided into four groups: (i) saline control group, (ii) NAC-treated group (N-acetylcysteine) (150 mg/kg), (iii) glycerol-treated group (50%, 8 ml/kg, IM) and (iv) NAC plus glycerol-treated group. Rats were sacrificed at 24 h after glycerol injection, and the blood and renal tissues were harvested.

RESULTS

Glycerol administration caused severe renal dysfunction, which included marked renal oxidative stress, significantly increased blood urea nitrogen (BUN) and serum creatinine levels. Histopathological findings, such as cast formation and tubular necrosis, confirmed renal impairment. We noted a marked activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), but not p-38, in the glycerol-treated group. We also observed high expression of Bax and Bad but only weak expression of Bcl-2 and Bcl-xL in the glycerol-treated group. However, NAC pretreatment significantly improved renal function and decreased the activation of ERK, JNK, Bax and Bad, whereas it increased Bcl-2 and Bcl-xL.

CONCLUSION

These results demonstrate that NAC protects against renal dysfunction, morphological damage and biochemical changes via the anti-apoptotic pathway in the glycerol-induced rhabdomyolysis model in rats.

In vitro anti-fibrotic activities of herbal compounds and herbs

BACKGROUND

We recently developed high-throughput assays of inflammation-independent anti-fibrotic activities based on TGF-beta1-induced total collagen accumulation and nodule formation in normal rat kidney fibroblasts.

METHODS

These assays were applied to examine the anti-fibrotic activities of 21 compounds isolated from plants used in Chinese medicine and methanol extracts of 12 Chinese herbs. Lactate dehydrogenase release assay and cell detachment index were used to monitor cytotoxicity. Changes in fibrogenic molecular markers were observed by reverse transcriptase quantitative polymerase chain reaction and high-content imaging analysis of immunofluorescence.

RESULTS

Three flavonoids (quercetin, baicalein and baicalin) and two non-flavonoids (salvianolic acid B and emodin) demonstrated anti-fibrotic activities in both total collagen accumulation and nodule formation assays. The remaining 16 compounds had little anti-fibrotic effect or were cytotoxic. The anti-fibrotic compounds suppressed collagen I expression at both mRNA and protein levels and also variably suppressed alpha-smooth muscle actin expression and bromodeoxyuridine incorporation. Methanol extracts of Scutellaria baicalensis Georgi, Salvia miltiorrhiza Bunge and Rheum palmatum L., which are rich sources of baicalein, baicalin, salvianolic acid B and emodin, respectively, also showed in vitro anti-fibrotic activities.

CONCLUSIONS

Five herbal compounds and three herbal extracts have in vitro anti-fibrotic activities. These data warrant further studies on these anti-fibrotic entities and suggest it a promising strategy to discover new anti-fibrotic drugs by screening more plant materials.

Quercetin prevents LPS-induced high-mobility group box 1 release and proinflammatory function

The pathogenesis of sepsis is mediated in part by the pathogen-associated molecular pattern molecule bacterial endotoxin, which stimulates macrophages to sequentially release early (e.g., TNF-alpha, IL-1beta) and late (e.g., high-mobility group box [HMGB] 1 protein) proinflammatory mediators. The recent discovery of HMGB1 as a late mediator of lethal sepsis has prompted investigation into development of several new experimental therapeutics that limit release, either blocking HMGB1 itself or its nominal receptors. Quercetin was recently identified as an experimental therapeutic that significantly protects against oxidative injury. Here, we report that quercetin attenuates lethal systemic inflammation caused by endotoxemia, even if treatment is started after the early TNF response. Quercetin treatment reduced circulating levels of HMGB1 in animals with established endotoxemia. In macrophage cultures, quercetin inhibited release as well as the cytokine activities of HMGB1, including limiting the activation of mitogen-activated protein kinase and NF-kappaB, two signaling pathways that are critical for HMGB1-induced subsequent cytokine release. Quercetin and autophagic inhibitor, wortmannin, inhibited LPS-induced type-II microtubule-associated protein 1A/1B-light chain 3 production and aggregation, as well as HMGB1 translocation and release, suggesting a potential association between autophagy and HMGB1 release. Quercetin delivery, a strategy to pharmacologically inhibit HMGB1 release that is effective at clinically achievable concentrations, now warrants further evaluation in sepsis and other systemic inflammatory disorders.

Dietary curcumin does not protect kidney in glycerol-induced acute renal failure

Generation of reactive oxygen species significantly contribute to the pathogenesis of renal injury induced by myoglobin release. The present study was performed to investigate the effects of dietary curcumin, a natural antioxidant isolated from plant Curcuma longa, in an experimental model of myoglobinuric acute renal failure. Rats received curcumin at an oral dose of 100mg/kg/day for 30 days. Renal injury was induced with injection of hypertonic glycerol (10 ml/kg 50% solution) in hind limb muscle with blood urea of 57.8+/-7.2 vs. 7.72+/-1.03 mmol/l and serum creatinine of 444.4+/-61.3 vs. 51.8+/-10.6 micromol/l, in glycerol-induced acute renal failure (ARF) vs. control rats, respectively. After 48 h rats were sacrificed and thiobarbituric acid reactive substance (TBARS), glutathione, carbonyl content and kidney cortex brush border peptidase activities were determined in serum, kidney and liver. Rats that received curcumin in addition to glycerol had significantly lower TBARS in serum but not in kidney and liver. Carbonyl content in kidney and liver was significantly elevated in curcumin and glycerol treated rats and improved in animals treated with curcumin and glycerol together. The activities of kidney cortex enzymes, aminopeptidase N, angiotensinase A and dipeptidyl peptidase IV, were reduced in glycerol as well as in curcumin treated rats. The results obtained in this study provided additional evidence that despite its limited antioxidant activity curcumin did not protect kidney in myoglobinuric model of ARF.

Flavonoid-induced acute nephropathy by Cupressus funebris Endl (Mourning Cypress)

Worldwide use of herbal therapy has increased dramatically in recent years. Most herbal therapies were not regulated as medicines, and their adverse effects often were underreported. We report a patient who developed acute renal failure, acute hepatic failure, autoimmune hemolytic anemia, and thrombocytopenia after oral intake of hot-water extract of Cupressus funebris Endl (Mourning Cypress), which is rich in flavonoids. Her renal biopsy showed acute tubular necrosis, interstitial nephritis, and hemoglobin casts. The clinical course and pathological findings were consistent with flavonoid-induced acute nephropathy. We emphasize that flavonoids are not harmless and may induce acute life-threatening renal damage.