Pleiotropic renal actions of erythropoietin

Delayed treatment with erythropoietin attenuates renal fibrosis in mouse model of unilateral ureteral obstruction

OBJECTIVES

Erythropoietin (EPO) exerts tissue-protective effects on various organs including the kidney. However, the effects of EPO on established renal fibrosis remain unclear. In this study, we aimed to examine the therapeutic potential of EPO against established renal fibrosis.

METHODS

Renal fibrosis was induced in mice by unilateral ureteral obstruction (UUO) and the mice were treated with recombinant human EPO (rhEPO) daily during 7 and 13 days after UUO. The degrees of renal fibrosis, myofibroblast accumulation, and macrophage infiltration; the mRNA expression levels of transforming growth factor (TGF)-β1 and α1(I) collagen; and the protein levels of Kelch-like ECH-associated protein 1 (Keap1) and nuclear NF-E2-related factor 2 (Nrf2) in the kidneys were assessed on day 14 after UUO.

RESULTS

Treatment with rhEPO significantly decreased fibrosis, myofibroblast accumulation, and α1(I) collagen mRNA expression, but it did not significantly affect TGF-β1 mRNA expression. Although treatment with rhEPO did not significantly affect the total number of interstitial macrophages, it significantly decreased the number of CD86-positive cells (M1 macrophages), while significantly increased the number of CD206-positive cells (M2 macrophages) in the interstitium. Treatment with rhEPO did not affect the Keap1/Nrf2 protein level or the peripheral blood hematocrit value.

CONCLUSIONS

These results indicate for the first time that EPO exerts antifibrotic effects against the evolution of established renal fibrosis, possibly by influencing the polarization of infiltrating macrophages.

Expression and Variations in EPO Associated with Oxygen Metabolism in Tibetan Sheep

After a long period of adaptive evolution, Tibetan sheep have adapted to the plateau environment in terms of genetics, physiology and biochemistry, but the mechanism of hypoxia adaptation has not been fully elucidated, and the functional genes and molecular mechanisms regulating the hypoxia adaptation of Tibetan sheep need to be further studied. In this study, Tibetan sheep were selected as the research object, and the mRNA expression levels of the hypoxa-related gene EPO in heart, lung, kidney, liver, spleen and longissimus dorsi muscle of Hu sheep (100 m) and Tibetan sheep at different altitudes (2500 m, 3500 m, 4500 m) were assessed by RT-qPCR. The SNPs loci were detected by sequencing and Kompetitive Allele-Specific PCR (KASP) technology, then the correlation between genetic polymorphism and blood gas was analyzed. The results show that the expression of the EPO gene was the highest in the kidney, indicating that the expression of EPO gene had tissue differences. The expression levels of the EPO gene in the heart, lung and liver of Tibetan sheep at a 4500 m altitude were significantly higher than those in Hu sheep (p < 0.05), and the levels in the hearts of Tibetan sheep increased with the increase in altitude. Three mutations were identified in the EPO gene, the SNPs (g.855 A > C) in exon 1 and the SNPs (g.1985 T > G and g.2115 G > C) in exon 4, which were named EPO-SNP1, EPO-SNP2 and EPO-SNP3, respectively, and all three SNPs showed three genotypes. Correlation analysis showed that g.2115 G > C sites were significantly correlated with pO2 (p < 0.05), and haplotype combinations were significantly correlated with pO2 (p < 0.05). Thesee results suggest that the expression of the EPO gene is altitude-differentiated and organ-differentiated, and the EPO gene variants have significant effects on pO2, which may be beneficial to the adaptation of Tibetan sheep to hypoxia stress.

Evolving Strategies in the Treatment of Anaemia in Chronic Kidney Disease: The HIF-Prolyl Hydroxylase Inhibitors

Chronic kidney disease (CKD) affects approximately 10% of the worldwide population; anaemia is a frequent complication. Inadequate erythropoietin production and absolute or functional iron deficiency are the major causes. Accordingly, the current treatment is based on iron and erythropoiesis stimulating agents (ESAs). Available therapy has dramatically improved the management of anaemia and the quality of life. However, safety concerns were raised over ESA use, especially when aiming to reach near-to-normal haemoglobin levels with high doses. Moreover, many patients show hypo-responsiveness to ESA. Hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD) inhibitors (HIF-PHIs) were developed for the oral treatment of anaemia in CKD to overcome these concerns. They simulate the body's exposure to moderate hypoxia, stimulating the production of endogenous erythropoietin. Some molecules are already approved for clinical use in some countries. Data from clinical trials showed non-inferiority in anaemia correction compared to ESA or superiority for placebo. Hypoxia-inducible factor-prolyl hydroxylase domain inhibitors may also have additional advantages in inflamed patients, improving iron utilisation and mobilisation and decreasing LDL-cholesterol. Overall, non-inferiority was also shown in major cardiovascular events, except for one molecule in the non-dialysis population. This was an unexpected finding, considering the lower erythropoietin levels reached using these drugs due to their peculiar mechanism of action. More data and longer follow-ups are necessary to better clarifying safety issues and further investigate the variety of pathways activated by HIF, which could have either positive or negative effects and could differentiate HIF-PHIs from ESAs.

Hypoxia-Inducible Factor Stabilizers in End Stage Kidney Disease: "Can the Promise Be Kept?"

Anemia is a common complication of chronic kidney disease (CKD). The prevalence of anemia in CKD strongly increases as the estimated Glomerular Filtration Rate (eGFR) decreases. The pathophysiology of anemia in CKD is complex. The main causes are erythropoietin (EPO) deficiency and functional iron deficiency (FID). The administration of injectable preparations of recombinant erythropoiesis-stimulating agents (ESAs), especially epoetin and darbepoetin, coupled with oral or intravenous(iv) iron supplementation, is the current treatment for anemia in CKD for both dialysis and non-dialysis patients. This approach reduces patients' dependence on transfusion, ensuring the achievement of optimal hemoglobin target levels. However, there is still no evidence that treating anemia with ESAs can significantly reduce the risk of cardiovascular events. Meanwhile, iv iron supplementation causes an increased risk of allergic reactions, gastrointestinal side effects, infection, and cardiovascular events. Currently, there are no studies defining the best strategy for using ESAs to minimize possible risks. One class of agents under evaluation, known as prolyl hydroxylase inhibitors (PHIs), acts to stabilize hypoxia-inducible factor (HIF) by inhibiting prolyl hydroxylase (PH) enzymes. Several randomized controlled trials showed that HIF-PHIs are almost comparable to ESAs. In the era of personalized medicine, it is possible to envisage and investigate specific contexts of the application of HIF stabilizers based on the individual risk profile and mechanism of action.

Erythropoietin in Lupus: Unanticipated Immune Modulating Effects of a Kidney Hormone

Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease with variable clinical presentation, typically characterized by a relapsing-remitting course. SLE has a multifactorial pathogenesis including genetic, environmental, and hormonal factors that lead to loss of tolerance against self-antigens and autoantibody production. Mortality in SLE patients remains significantly higher than in the general population, in part because of the limited efficacy of available treatments and the associated toxicities. Therefore, novel targeted therapies are urgently needed to improve the outcomes of affected individuals. Erythropoietin (EPO), a kidney-produced hormone that promotes red blood cell production in response to hypoxia, has lately been shown to also possess non-erythropoietic properties, including immunomodulatory effects. In various models of autoimmune diseases, EPO limits cell apoptosis and favors cell clearance, while reducing proinflammatory cytokines and promoting the induction of regulatory T cells. Notably, EPO has been shown to reduce autoimmune response and decrease disease severity in mouse models of SLE. Herein, we review EPO's non-erythropoietic effects, with a special focus on immune modulating effects in SLE and its potential clinical utility.

Anemia in patients of diabetic kidney disease

Anemia is the major complication resulting from chronic kidney disease (CKD) and also a risk factor for cardiovascular events and a poor quality of life (QoL). Diabetic kidney disease (DKD) is the major cause of CKD. Initially, insulin resistance has been reported to increase erythropoiesis, but it might be a minor issue. DKD-related anemia developed earlier and was more severe than non-DKD-related anemia based on more complicated mechanisms, including greater bleeding tendency associated with antiplatelet effect, less O2 sensing due to autonomic neuropathy or renin-angiotensin-aldosterone system inhibitor use, inhibitory effect of inflammatory cytokines, urinary loss of erythropoietin (EPO), and poor response to EPO. In DKD patients, prompt correction of anemia allows for a better cardiovascular outcome and QoL, which are similar to the promising effect of anemia correction in CKD patients. However, current evidence recommended that the avoidance of a high or normalized hemoglobin (Hb) level has been suggested in the treatment of anemia in DKD patients. Despite that EPO has a pleotropic effect on renal protection from animal studies, the renal benefit was less evident in CKD and DKD patients. Recently, the antidiabetic agent, sodium glucose cotransporter-2 inhibitors (SGLT2i), has been reported to exhibit the renal benefits due to the tubulo-glomerular feedback in addition to sugar control. It may also be due to less renal ischemic through higher EPO levels, followed by higher Hb levels. More studies are needed to clarify the link between the renal benefit of SGLT2i and EPO production.

Prevention of contrast-induced nephropathy with single bolus erythropoietin in patients with diabetic kidney disease: A randomized controlled trial

AIM

Contrast-induced-nephropathy (CIN) is associated with poor outcomes, thus prevention of CIN may be of clinical value. Erythropoietin (EPO) has been shown to elicit tissue-protective effects in experimental models and in clinical studies of acute kidney injury. We therefore evaluated its effectiveness for prevention of CIN after coronary angiography (CA) ± percutaneous coronary intervention (PCI) in diabetic patients with chronic kidney disease.

METHODS

A prospective, randomized, controlled trial was carried out in 138 diabetic patients with eGFR <60 mL/min who underwent non-urgent CA ± PCI. Patients received normal saline and n-acetyl cysteine before CA, with or without 50,000 U of EPO administered 30 min prior to CA. CIN was defined as an increase in serum creatinine of at least 0.5 mg/dL during the first 2 days after exposure to contrast media. Primary outcome was the incidence of CIN. Secondary outcomes were the sensitivity and positive predictive value (PPV) of Cystatin C (CC) and Neutrophil-gelatinase-associated-lipocalin (NGAL) for diagnosis of CIN.

RESULTS

The observed incidence of CIN was 8.7%, significantly lower than the expected for such high-risk population. The administration of EPO prior to CA did not reduce the incidence of CIN (9.7% vs. 7.6%, P = 0.65). CC and NGAL demonstrated a low sensitivity (16.6%) and low PPV (6.7 and 33.3%, respectively) for detecting CIN.

CONCLUSION

The administration of EPO prior to CA did not reduce the incidence of CIN. Additional prospective research with a larger sample size and in other patient categories is essential to further define the potential protective effect of EPO on prevention of CIN.

Possible Inhibitory Effect of Erythropoiesis-Stimulating Agents at the Predialysis Stage on Early-Phase Coronary Events after Hemodialysis Initiation

BACKGROUND

We examined whether the use of erythropoiesis-stimulating agents (ESAs) to correct anemia at the predialysis stage could inhibit early-phase coronary events after hemodialysis initiation.

METHODS

We enrolled 242 patients with chronic kidney disease who had received continued medical treatments and initiated maintenance hemodialysis from 1 September 2000 to 31 December 2014 at Toujinkai Hospital. Patients with a previous history of blood transfusion or any cardiovascular events or interventions were excluded. The coronary events were followed for 1 year after initiation of hemodialysis.

RESULTS

Coronary events occurred in 51 of 242 patients: 10 patients had acute coronary syndrome [9 with percutaneous coronary intervention (PCI), 1 without intervention], and 41 had elective coronary revascularization (38 PCI and 3 coronary artery bypass graft). ESA was administered in 118 of 242 patients (48.8%). In stepwise logistic analysis, coronary events were positively associated with nonuse of ESA at the predialysis stage (odds ratio 2.66, p = 0.005) and diabetes mellitus (odds ratio 5.33, p < 0.001). When dividing the patients into 4 subgroups by blood hemoglobin (Hb) level (8.5 g/dl) and the use/nonuse of ESA, coronary event-free survival rates were higher (p = 0.005) in those with Hb ≥8.5 g/dl, ESA+ (86.6%, n = 82) and tended to be higher (p = 0.055) in those with Hb <8.5 g/dl, ESA+ (86.1%, n = 36) than in patients with Hb <8.5 g/dl, ESA- (68.6%, n = 86) in a Kaplan-Meier analysis.

CONCLUSIONS

The use of ESA to correct anemia at the predialysis stage may inhibit early-phase coronary events after hemodialysis initiation.

Impact of Continuous Erythropoietin Receptor Activator on Selected Biomarkers of Cardiovascular Disease and Left Ventricle Structure and Function in Chronic Kidney Disease

Background. Cardiovascular morbidity and mortality are very high in patients with chronic kidney disease (CKD). The purpose of this study is to evaluate the impact of continuous erythropoietin receptor activator (CERA) on selected biomarkers of cardiovascular disease, left ventricle structure, and function in CKD. Material and Methods. Peripheral blood was collected from 25 CKD patients before and after CERA treatment and 20 healthy subjects. In serum samples, we assessed inflammatory markers (IL-1β, TNF-RI, TNF-RII, sFas, sFasL, MMP-9, TIMP-1, and TGF-β1), endothelial dysfunction markers (sE-selectin, sICAM-1, and sVCAM-1), and volume-related marker (NT-proBNP). All subjects underwent echocardiography and were evaluated for selected biochemical parameters (Hb, creatinine, and CRP). Results. Evaluated biomarkers and echocardiographic parameters of left ventricle structure were significantly increased but left ventricle EF was significantly decreased in CKD patients compared to controls. After CERA treatment, we observed a significant increase of Hb and left ventricle EF and a significant decrease of NT-proBNP and MMP-9. There was a significant negative correlation between Hb and TNF-RI, sICAM-1, and IL-1β. Conclusions. Our results indicate that selected biomarkers related to cardiovascular risk are significantly increased in CKD patients compared to controls. CERA treatment has anti-inflammatory action, diminishes endothelial dysfunction, and improves left ventricle function in these patients.

Erythropoiesis-stimulating agent slows the progression of chronic kidney disease: a possibility of a direct action of erythropoietin

BACKGROUND

Controversy exists regarding the renoprotective effect of erythropoiesis-stimulating agent (ESA) in progressive chronic kidney disease (CKD) with renal anemia. In this study, we examined whether ESA therapy has a renoprotective effect in progressive CKD.

METHODS

The subjects in this retrospective observational study were 68 non-dialysis dependent CKD patients with renal anemia. We compared the progression rate (PR), defined by the slope of the linear regression line of estimated glomerular filtration rate, measured during 6 months just before and after the start of ESA therapy. We also investigated the factors affecting renoprotective efficacy of ESA therapy against the progression of CKD.

RESULTS

Median (interquartile range) PR decreased significantly from 6.2 (3.7-12.7) to 4.0 (-0.3 to 7.3) mL/min/1.73 m(2)/year after the start of ESA therapy. Blood pressure levels and rate of medication with renin-angiotensin system inhibitors were comparable between the two periods. Next, we investigated the factors affecting renoprotective efficacy of ESA therapy against the progression of CKD. Thirty patients were good renal responders, defined as those with the ratio of post-/pre-PR of <0.5 and the difference of pre- minus post-PR >5.0 mL/min/1.73 m(2)/year, and 38 patients were poor renal responders who did not meet the definition of good renal responders. Multivariable logistic regression analysis showed that weekly ESA dose, but not increase in hemoglobin level, was a significant and independent determinant of the renoprotective effect of ESA.

CONCLUSION

ESA therapy slows the progression of CKD and part of the effect might be attributed to the direct renoprotective action of ESA.

Mitochondrial Quality Control as a Therapeutic Target

In addition to oxidative phosphorylation (OXPHOS), mitochondria perform other functions such as heme biosynthesis and oxygen sensing and mediate calcium homeostasis, cell growth, and cell death. They participate in cell communication and regulation of inflammation and are important considerations in aging, drug toxicity, and pathogenesis. The cell's capacity to maintain its mitochondria involves intramitochondrial processes, such as heme and protein turnover, and those involving entire organelles, such as fusion, fission, selective mitochondrial macroautophagy (mitophagy), and mitochondrial biogenesis. The integration of these processes exemplifies mitochondrial quality control (QC), which is also important in cellular disorders ranging from primary mitochondrial genetic diseases to those that involve mitochondria secondarily, such as neurodegenerative, cardiovascular, inflammatory, and metabolic syndromes. Consequently, mitochondrial biology represents a potentially useful, but relatively unexploited area of therapeutic innovation. In patients with genetic OXPHOS disorders, the largest group of inborn errors of metabolism, effective therapies, apart from symptomatic and nutritional measures, are largely lacking. Moreover, the genetic and biochemical heterogeneity of these states is remarkably similar to those of certain acquired diseases characterized by metabolic and oxidative stress and displaying wide variability. This biologic variability reflects cell-specific and repair processes that complicate rational pharmacological approaches to both primary and secondary mitochondrial disorders. However, emerging concepts of mitochondrial turnover and dynamics along with new mitochondrial disease models are providing opportunities to develop and evaluate mitochondrial QC-based therapies. The goals of such therapies extend beyond amelioration of energy insufficiency and tissue loss and entail cell repair, cell replacement, and the prevention of fibrosis. This review summarizes current concepts of mitochondria as disease elements and outlines novel strategies to address mitochondrial dysfunction through the stimulation of mitochondrial biogenesis and quality control.

Acute Kidney Injury in Cardiac Surgery and Cardiac Intensive Care

Acute kidney injury (AKI) is a serious postoperative complication following cardiac surgery. Despite the incidence of AKI requiring temporary renal replacement therapy being low, it is nonetheless associated with high morbidity and mortality. Therefore, preventing AKI associated with cardiac surgery can dramatically improve outcomes in these patients. The pathogenesis of AKI is multifactorial and many attempts to prevent or treat renal injury have been met with limited success. In this article, we will discuss the incidence and risk factors for cardiac surgery associated AKI, including the pathophysiology, potential biomarkers of injury, and treatment modalities.

Molecular mechanisms of ischemic preconditioning in the kidney

More effective therapeutic strategies for the prevention and treatment of acute kidney injury (AKI) are needed to improve the high morbidity and mortality associated with this frequently encountered clinical condition. Ischemic and/or hypoxic preconditioning attenuates susceptibility to ischemic injury, which results from both oxygen and nutrient deprivation and accounts for most cases of AKI. While multiple signaling pathways have been implicated in renoprotection, this review will focus on oxygen-regulated cellular and molecular responses that enhance the kidney's tolerance to ischemia and promote renal repair. Central mediators of cellular adaptation to hypoxia are hypoxia-inducible factors (HIFs). HIFs play a crucial role in ischemic/hypoxic preconditioning through the reprogramming of cellular energy metabolism, and by coordinating adenosine and nitric oxide signaling with antiapoptotic, oxidative stress, and immune responses. The therapeutic potential of HIF activation for the treatment and prevention of ischemic injuries will be critically examined in this review.

Impact of anemia treatment with methoxy polyethylene glycol-epoetin beta on polymorphonuclear cells apoptosis in predialysis patients with chronic kidney disease

BACKGROUND

Some data in literature indicate increased apoptosis of polymorphonuclear cells (PMNs) in chronic kidney disease (CKD), what seems to be connected with anemia. Erythropoiesis-stimulating agents, used in anemia treatment in CKD may affect cells apoptosis. Aim of this study was to investigate impact of anemia treatment with methoxy polyethylene glycol-epoetin beta (CERA) on PMNs apoptosis in predialysis patients with CKD.

METHODS

Percentage of early and late apoptotic PMNs was measured by flow cytometry based on annexin V and propidium iodide binding. CD90 (Fas), CD95L (FasL), CD16 and CD11b expression on PMNs were evaluated by flow cytometry after incubation with respective monoclonal antibody.

RESULTS

Percentage of PMNs in early and late apoptosis in CKD patients before CERA treatment was significantly higher to control group, which was accompanied by significantly higher Fas and Fas-L expression and significantly lower expression of CD16. CERA treatment downregulated significantly percentage of early, apoptotic PMNs but percentage of late apoptotic cells did not change and was still significantly higher to control group. In all investigated groups we observed a significant negative correlation between hemoglobin concentration and percentage of apoptotic PMNs, as well as Fas and FasL expression and significant positive correlation between Hb and CD16 expression.

CONCLUSIONS

Our results indicate that PMNs apoptosis is increased in predialysis patients with CKD and anemia treatment with CERA may diminish readiness of PMNs to undergo apoptosis. This antiapoptotic impact of anemia treatment with CERA seems to concern early apoptotic PMNs before they undergo to late, irreversible stage of apoptosis.

Effect of recombinant human erythropoietin on mitomycin C-induced oxidative stress and genotoxicity in rat kidney and heart tissues

Mitomycin C (MMC) is an antineoplastic agent used for the treatment of several human malignancies. Nevertheless, the prolonged use of the drug may result in a serious heart and kidney injuries. Recombinant human erythropoietin (rhEPO) has recently been shown to exert an important cytoprotective effect in experimental brain injury and ischemic acute renal failure. The aim of the present work is to investigate the cardioprotective and renoprotective effects of rhEPO against MMC-induced oxidative damage and genotoxicity. Our results showed that MMC induced oxidative stress and DNA damage. rhEPO administration in any treatment conditions decreased oxidative damage induced by MMC. It reduced malondialdehyde and protein carbonyl levels. rhEPO ameliorated reduced glutathione plus oxidized glutathione modulation and the increased catalase activity after MMC treatment. Furthermore, rhEPO restored DNA damage caused by MMC. We concluded that rhEPO administration especially in pretreatment condition protected rats against MMC-induced heart and renal oxidative stress and genotoxicity.

Activation of mitochondrial function and Hb expression in non-haematopoietic cells by an EPO inducer ameliorates ischaemic diseases in mice

BACKGROUND AND PURPOSE

Many organs suffer from ischaemic injuries that reduce their ability to generate sufficient energy, which is required for functional maintenance and repair. Erythropoietin (EPO) ameliorates ischaemic injuries by pleiotropic effects. The aim of this study was to investigate the effect and mechanism of a small molecule EH-201, and found it as a potent EPO inducer and its effect in non-haematopoietic cells for therapeutic potential in ischemic disorders.

EXPERIMENTAL APPROACH

Mice kidney slices, primary hepatocytes, primary cardiomyocytes and C2C12 myoblasts were treated with EH-201. The effects of this treatment on EPO, Hb expression and mitochondrial biogenesis were analysed. In vivo, doxorubicin-induced cardiomyopathic mice were treated with EH-201. The mice were subjected to an endurance test, electrocardiography and echocardiography, and a histological examination of the isolated hearts was performed. EH-201 was also administered to cisplatin-induced nephropathic mice.

KEY RESULTS

In non-haematopoietic cells, EH-201 was potent at inducing EPO. EH-201 also stimulated mitochondrial biogenesis and enhanced the expression of Hb by a mechanism dependent on EPO-mediated signalling. In mechanistic studies, using EPO and EPO receptor-neutralizing antibodies, we confirmed that EH-201 enhances EPO-EPOR autocrine activity. EH-201 robustly increased the endurance performance activity of healthy and cardiomyopathic mice during hypoxic stress, enhanced myocardial mitochondrial biogenesis and Hb expression, and also improved cardiac function. EH-201 ameliorated anaemia and renal dysfunction in nephropathic mice.

CONCLUSIONS AND IMPLICATIONS

The enhancement and recovery of cellular functions through the stimulation of mitochondrial activity and Hb production in non-haematopoietic cells by an inducer of endogenous EPO has potential as a therapeutic strategy for ischaemic diseases.

Darbepoetin alpha reduces oxidative stress and chronic inflammation in atherosclerotic lesions of apo E deficient mice in experimental renal failure

Background

Cardiovascular morbidity and mortality is very important in patients with chronic renal failure. This occurs even in mild impairment of renal function and may be related to oxidative stress and chronic inflammation. The nephrectomized apo E knockout mouse is an accepted model for evaluating atherosclerosis in renal dysfunction. Erythropoietin derivates showed anti-oxidative and anti-inflammatory effects. Therefore, this study evaluates the effects of Darbepoetin on markers of oxidative stress and chronic inflammation in atherosclerotic lesions in apo E knockout mice with renal dysfunction.

Methods

Apo E knockout mice underwent unilateral (Unx, n = 20) or subtotal (Snx, n = 26) nephrectomy or sham operation (Sham, n = 16). Mice of each group were either treated with Darbepoetin or saline solution, a part of Snx mice received a tenfold higher dose of Darbepoetin. The aortic plaques were measured and morphologically characterized. Additional immunhistochemical analyses were performed on tissue samples taken from the heart and the aorta.

Results

Both Unx and Snx mice showed increased expression of markers of oxidative stress and chronic inflammation. While aortic plaque size was not different, Snx mice showed advanced plaque stages when compared to Unx mice. Darbepoetin treatment elevated hematocrit and lowered Nitrotyrosin as one marker of oxidative stress, inflammation in heart and aorta, plaque stage and in the high dose even plaque cholesterol content. In contrast, there was no influence of Darbepoetin on aortic plaque size; high dose Darbepoetin treatment resulted in elevated renal serum parameters.

Conclusion

Darbepoetin showed some protective cardiovascular effects irrespective of renal function, i.e. it improved plaque structure and reduced some signs of oxidative stress and chronic inflammation without affecting plaque size. Nevertheless, the dose dependent adverse effects must be considered as high Darbepoetin treatment elevated serum urea. Elevation of hematocrit might be a favorable effect in anemic Snx animals but a thrombogenic risk in Sham animals.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

Erythropoietin-mediated protection in kidney transplantation: nonerythropoietic EPO derivatives improve function without increasing risk of cardiovascular events

The protective, nonerythropoietic effects of erythropoietin (EPO) have become evident in preclinical models in renal ischaemia/reperfusion injury and kidney transplantation. However, four recently published clinical trials using high-dose EPO treatment following renal transplantation did not reveal any protective effect for short-term renal function and even reported an increased risk of thrombosis. This review focusses on the current status of protective pathways mediated by EPO, the safety concerns using high EPO dosage and discusses the discrepancies between pre-clinical and clinical studies. The protective effects are mediated by binding of EPO to a heteromeric receptor complex consisting of two β-common receptors and two EPO receptors. An important role for the activation of endothelial nitric oxide synthase is proposed. EPO-mediated cytoprotection still has enormous potential. However, only nonerythropoietic EPO derivatives may induce protection without increasing the risk of cardiovascular events. In preclinical models, nonerythropoietic EPO derivatives, such as carbamoylated EPO and ARA290, have been tested. These EPO derivatives improve renal function and do not affect erythropoiesis. Therefore, nonerythropoietic EPO derivatives may be able to render EPO-mediated cytoprotection useful and beneficial for clinical transplantation.

Cardiac antiapoptotic and proproliferative effect of recombinant human erythropoietin in a moderate stage of chronic renal failure in the rat

Objective:

Recombinant human erythropoietin (rhEPO) therapy under circumstances of moderate chronic renal failure (CRF), with yet lower kidney and heart lesion, may have a protective cardiac effect beyond the correction of anemia, whose mechanism deserves better elucidation, namely by clarifying the impact on gene expression profile of markers of apoptosis, inflammation, proliferation, angiogenesis, and lesion/stress in the heart.

Materials and Methods:

Four groups of rats were studied over a period of 15 weeks (n=7 each): control—without surgery and without drug treatment; rhEPO—treated with 50 IU/kg/week of rhEPO—beta; CRF—submitted to partial nephrectomy (3/4); CRF + rhEPO—CRF with rhEPO treatment after the 3rd week of surgery. The heart was collected in order to evaluate the gene expression, by real-time qPCR, of markers of apoptotic machinery, inflammation/immunology, proliferation/angiogenesis, and lesion/stress.

Results:

The main findings obtained were (a) CRF rats have demonstrated overexpression of EPO-R in the heart without changes on EPO expression, together with overexpression of Bax/Bcl2 ratio, PCNA, and IL-2; (b) rhEPO therapy on the heart of the rats with CRF induced by partial 3/4 nephrectomy promoted nonhematopoietic protection, demonstrated by the apoptosis prevention, viewed by the Bax/Bcl2 balance, by the promotion of proliferation, due to PCNA increment, and by the immunomodulatory action, expressed by a trend to prevent the IL-2 increment.

Conclusion:

In this model of moderate CRF, rhEPO treatment showed important cardiac nonhematopoietic effects, expressed mainly by the antiapoptotic and the proproliferative action, suggesting that early rhEPO therapy in moderate stages of CRF might have further therapeutic benefits.

Cardiorenal syndrome: pathophysiology and potential targets for clinical management

Combined dysfunction of the heart and the kidneys, which can be associated with haemodynamic impairment, is classically referred to as cardiorenal syndrome (CRS). Cardiac pump failure with resulting volume retention by the kidneys, once thought to be the major pathophysiologic mechanism of CRS, is now considered to be only a part of a much more complicated phenomenon. Multiple body systems may contribute to the development of this pathologic constellation in an interconnected network of events. These events include heart failure (systolic or diastolic), atherosclerosis and endothelial cell dysfunction, uraemia and kidney failure, neurohormonal dysregulation, anaemia and iron disorders, mineral metabolic derangements including fibroblast growth factor 23, phosphorus and vitamin D disorders, and inflammatory pathways that may lead to malnutrition-inflammation-cachexia complex and protein-energy wasting. Hence, a pathophysiologically and clinically relevant classification of CRS based on the above components would be prudent. With the existing medical knowledge, it is almost impossible to identify where the process has started in any given patient. Rather, the events involved are closely interrelated, so that once the process starts at a particular point, other pathways of the network are potentially activated. Current therapies for CRS as well as ongoing studies are mostly focused on haemodynamic adjustments. The timely targeting of different components of this complex network, which may eventually lead to haemodynamic and vascular compromise and cause refractoriness to conventional treatments, seems necessary. Future studies should focus on interventions targeting these components.

The protective effect of recombinant human erythropoietin against cisplatin-induced renal and hepatic dysfunctions in Wistar rats

Cisplatin (Cisp) is one of the most effective chemotherapeutic drugs. However, the dose of Cisp is greatly limited by its toxicity. Recombinant human erythropoietin (rhEPO), a hormone that regulates hematopoiesis, has also been shown to exert tissue-protective effects. The purpose of this study was to explore the protective effect of rhEPO against Cisp-induced renal and liver dysfunctions. Adult male Wistar rats were divided into six groups of six each: control, rhEPO-alone group, Cisp-alone group and rhEPO + Cisp group (pretreatment, cotreatment and posttreatment conditions). Our results showed that Cisp-induced a marked renal and liver failure characterized by a significant decrease in body weight, organ weight and organ ratio and a significant increase in creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, G-glutamyl transferase, alkaline phosphatase, bilirubin conjugated and bilirubin total levels in serum. Histological examination showed that Cisp caused kidney alterations. rhEPO treatments restored body weight, organ weight and organ ratio as well as serum biochemical parameters changed due to Cisp exposure.

Induction of DNA fragmentation, chromosome aberrations and micronuclei by cisplatin in rat bone-marrow cells: protective effect of recombinant human erythropoietin

Cisplatin (Cisp) is one of the most effective chemotherapeutic agents. However, at higher doses several side effects may occur. Recombinant human erythropoietin (rhEPO), a glycoprotein regulating haematopoiesis, has recently been shown to exert an important cyto-protective effects in many tissues. The purpose of this study was to explore whether rhEPO protects against Cisp-induced genotoxicity in rat bone-marrow cells. Adult male Wistar rats were divided into six groups of 18 animals each: control group, rhEPO-alone group, Cisp-alone group and three rhEPO+Cisp-groups (pre-, co- and post-treatment condition, respectively). Our results show that Cisp induced a noticeable genotoxic effect in rat bone-marrow cells. In all types of treatment, rhEPO significantly decreased the frequency of micronuclei, the percentage of chromosome aberrations and the level of DNA damage. The protective effect of rhEPO was more efficient when it was administrated 24h before exposure to Cisp.

Erythropoietin attenuated vascular dysfunction and inflammation by inhibiting NADPH oxidase-derived superoxide production in nitric oxide synthase-inhibited hypertensive rat aorta

Erythropoietin (EPO), used clinically for renal anemia, reportedly exerts beneficial pleiotropic effects in various tissues. Recent studies suggest that nitric oxide (NO) plays an important role in EPO-induced tissue protection. The present study investigated whether recombinant human EPO (rHuEPO) exhibits vasoprotective effects even in the NO synthase-inhibited state. Rats that received a NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), in drinking water (0.7 mg/ml) were treated with rHuEPO (75 U/kg, s.c.) three times a week for 2 weeks. The administration of rHuEPO to L-NAME-treated rats had no effect on hematocrit values or increased blood pressure. Vasodilation in response to acetylcholine in the aortic ring was impaired in the L-NAME-treated rats, and improved by rHuEPO. Immunohistochemical staining revealed that infiltration by macrophages and expression of osteopontin were enhanced in the L-NAME-treated rat aorta, and the overexpression was suppressed by rHuEPO. rHuEPO also attenuated medial hyperplasia. Activation of Akt signaling was evident in rHuEPO-treated rats as the increased expression of phosphorylated Akt. rHuEPO enhanced the expression of antioxidant enzymes such as Cu/Zn-superoxide dismutase and heme oxygenase-1 in the aorta. In addition, rHuEPO reduced NADPH oxidase-dependent superoxide production and enhanced the expression of suppressor of cytokine signaling-1(SOCS-1) in the L-NAME-treated rat aorta. These results suggest that a low dose of rHuEPO results in the normalization of endothelial function and vascular inflammation beyond hematopoiesis even in a pharmacologically NO synthase-inhibited state. These effects might be due to the antioxidant properties of rHuEPO. SOCS-1 overexpression would play an important role in suppressing NADPH oxidase activation.

A nonerythropoietic derivative of erythropoietin inhibits tubulointerstitial fibrosis in remnant kidney

BACKGROUND

The tissue-protective effects of erythropoietin (EPO) have been extensively investigated, and EPO administration can raise the hemoglobin (Hb) concentration. Recently, we reported that carbamylated erythropoietin (CEPO) protected kidneys from ischemia-reperfusion injury as well as EPO.

METHODS

To investigate the clinical applications of CEPO, we next evaluated the long-term therapeutic effect of CEPO using a tubulointerstitial model rat. We randomized remnant kidney model rats to receive saline, EPO, or CEPO for 8 weeks.

RESULTS

CEPO- and EPO-treated rats had improved serum creatinine levels compared with saline-treated remnant kidney model rats, although the Hb level was significantly increased in EPO-treated rats. Two-photon microscopy revealed that EPO/CEPO significantly ameliorated tubular epithelial cell damage assessed by endocytosis. In addition, CEPO or EPO protected endothelial cells with a sustained blood flow rate. EPO or CEPO suppressed the number of TUNEL-positive apoptotic cells with weak αSMA staining. Furthermore, PCR analysis demonstrated that TGF-β and type I collagen expression was attenuated in EPO- or CEPO-treated rats, accompanied by a significant decrease in interstitial fibrosis.

CONCLUSION

We established a long-term therapeutic approach to protect tubulointerstitial injury with CEPO, and thus, the therapeutic value of this approach warrants further attention and preclinical studies.

Protective effect of recombinant human erythropoietin against cisplatin-induced oxidative stress and nephrotoxicity in rat kidney

Cisplatin (Cisp) is one of the most widely used chemotherapeutic agents for the treatment of several human malignancies. The efficacy of Cisp is dose dependent and at higher doses serious kidney injury may occur. Recombinant human erythropoietin (rhEPO) has recently been shown to exert an important cytoprotective effect in experimental brain injury and ischemic acute renal failure. The aim of the present study was to explore whether rhEPO administration is protective against Cisp-induced oxidative damage and renal injury. Our results showed that Cisp induced a marked oxidative stress and renal failure. Administration of rhEPO (pre-, co- or postadministration with regard to Cisp) decreased oxidative damage induced by Cisp. Recombinant human EPO reduced malondialdehyde and protein carbonyl levels. Recombinant human EPO also prevented glutathione depletion and ameliorated the increased catalase activity induced by Cisp treatment. Furthermore, rhEPO restored creatinine and blood urea nitrogen levels increased by Cisp. We concluded that rhEPO administration especially in pretreatment condition protected rats against Cisp-induced renal oxidative stress and nephrotoxicity.

Recombinant human erythropoietin prevents cisplatin-induced genotoxicity in rat liver and heart tissues via an antioxidant process

Cisplatin (Cisp) is one of the most effective chemotherapeutic agents. However, at higher doses, liver and heart injuries may occur. Recombinant human erythropoietin (rhEPO) has recently been shown to exert an important cytoprotective effect in many tissues. For that reason, we tried to check the protective effect of rhEPO against Cisp-induced genotoxicity and oxidative stress in liver and heart tissues. Our experiments were performed using six groups of adult male Wistar rats. The control group was treated only with saline solution. The rhEPO group was given a single dose of rhEPO. The Cisp group was given a single injection of Cisp. The rhEPO+Cisp groups were given rhEPO simultaneously, 24 hours before, and 5 days after Cisp injection. Our results clearly showed that Cisp induced noticeable DNA damage in the liver and heart, accompanied by a significant increase in protein carbonyl level, reduced glutathione (GSH) depletion, and a decrease in catalase activity. Rats treated with rhEPO, simultaneously, before, or after Cisp injection, remarkably decreased DNA damage. It decreased also the protein carbonyl level, restored GSH depletion, and enhanced catalase activity. Our results highlight an interesting cytoprotective strategy using rhEPO against Cisp-induced liver and heart injuries.

Erythropoietin prevents vascular inflammation and oxidative stress in subtotal nephrectomized rat aorta beyond haematopoiesis

1. Recombinant human erythropoietin (rHuEPO) has been used for the management of renal anaemia. Recent studies suggest pleiotropic properties of rHuEPO in various tissues. The aim of the present study was to investigate the vasoprotective effects of rHuEPO in renal failure rats. 2. Rats subjected to 5/6 and 17/18 nephrectomy (5/6Nx and 17/18Nx rats, respectively) were treated with rHuEPO (75 U/kg, s.c.) three times a week for 2 weeks. 3. Administration of rHuEPO to 5/6Nx or 17/18Nx rats had no effect on systolic blood pressure or decreased haematocrit. However, rHuEPO treatment normalized proteinuria and creatinine clearance in 5/6Nx, but not in 17/18Nx, rats. 4. Vasodilation in response to acetylcholine in aortic rings was impaired in 5/6Nx and 17/18Nx rats and improved by rHuEPO in both groups. Immunohistochemical analysis revealed that macrophage infiltration into adventitial areas and the expression of osteopontin were enhanced in aortas from 5/6Nx and 17/18Nx rats, but that rHuEPO suppressed these effects. In addition, rHuEPO attenuated medial hyperplasia and NADPH oxidase-derived superoxide production in 5/6Nx and 17/18Nx rats. 5. Activation of the Akt signalling pathway was evident in rHuEPO-treated rats as the increased expression of phosphorylated Akt and glycogen synthase kinase-3β. Treatment with rHuEPO restored the expression of phosphorylated endothelial nitric oxide synthase in the aorta and urinary excretion of NO(x) in nephrectomized rats. 6. These results suggest that a low dose of rHuEPO results in the normalization of endothelial function, vascular inflammation and oxidative stress in rats with renal ablation beyond haematopoiesis. In addition, these vasoprotective effects are observed even in a state of deteriorating renal dysfunction.

Relation between renal dysfunction requiring renal replacement therapy and promoter polymorphism of the erythropoietin gene in cardiac surgery

Several genetic polymorphisms have been identified to play a role in the occurrence and progression of renal dysfunction after cardiac surgery with cardiopulmonary bypass (CPB). Recently, it was demonstrated that the T allele of SNP rs1617640 in the promoter of the erythropoetin (EPO) gene is significantly associated with proliferative diabetic retinopathy (PDR) and end-stage renal disease (ESRD) due to increased EPO expression. This disease risk-associated gene and its potential pathway mediating severe microvascular complications in T-allele carriers could also play a role on renal dysfunction in patients who underwent cardiac surgery with CPB. We hypothesized that the patients' ability to produce increased EPO concentrations will affect morbidity and mortality after CPB. We conducted a prospective single center study between April 2006 and May 2007. In 481 patients who underwent cardiac surgery with CPB we prospectively examined the SNP rs1617640 in the promoter of the EPO gene by DNA sequencing. The patients were grouped according to their genotype (GG, GT, and TT). The genotype distribution of SNP rs1617640 in the promoter of the EPO gene was 36% (TT), 49% (TG), and 15% (GG). There was no difference in age, body mass index, gender, CPB time, or length of stay in intensive care unit. The hospitalization was irrespective of the patients' genotypes. The baseline creatinine in the TT group was 0.2 points higher than in the other groups; however this was without statistical significance in the multivariate analysis. No significant difference was shown in Euroscore, the Simplified Acute Physiology Score II, the Acute Physiology and Chronic Health Evaluation Score II, Acute Renal Failure Score, or the Risk, Injury, Failure, Loss of Kidney Function Score. The mortality was equal across the genotypes. However, an association between the TT genotype and acute renal replacement therapy (P=0.03), intra-aortic balloon pump usage (P=0.02), and serum creatine phosphokinase-MB increase (P=0.03) were observed after cardiac surgery. Our analysis suggests that the risk allele (T) of rs1617640 plays a role in the development of renal dysfunction after cardiac surgery with CPB. Patients with the TT risk allele required more frequent acute renal replacement therapy. Since our result is close to the border of significance, this hypothesis should be investigated in larger prospective studies with long-term follow-up to emphasize this polymorphism as a potential risk factor.

Darbepoetin-α inhibits the perpetuation of necro-inflammation and delays the progression of cholestatic fibrosis in mice

Biliary obstruction and cholestasis result in hepatocellular necro-inflammation and lead to the development of liver fibrosis. The objective of this study was to analyze whether the multiple tissue-protective properties of erythropoietin are salutary in an experimental model of liver fibrosis. For this purpose, C57BL/6J mice underwent common bile duct ligation (BDL) and were treated with either darbepoetin-α (10 μg/kg i.p.) or physiological saline every third day, beginning 24 h after BDL. Mice were killed at 2, 5, 14, and 28 days after BDL. Beside hematological parameters, markers of inflammation and fibrosis were assessed histomorphometrically and immunohistochemically as well as by quantitative real-time PCR. In addition, a 7-week survival study was performed. BDL provoked cholestatic hepatitis characterized by biliary infarcts with accumulation of macrophages followed by marked collagen deposition and increased expression of profibrotic gene transcripts. Darbepoetin-α treatment significantly diminished the area of focal necrosis, reduced the infiltration of macrophages, decreased levels of profibrotic genes, and lowered collagen deposition. Moreover, darbepoetin-α significantly reduced systemic anemia caused by BDL. Finally, darbepoetin-α treatment significantly prolonged the survival time after BDL. This study suggests that darbepoetin-α, which is a clinically well-established substance, might be used as an efficient therapeutic option for patients with chronic cholestatic liver disease.

Darbepoetin-α treatment enhances glomerular regenerative process in the Thy-1 glomerulonephritis model

Recent studies have demonstrated that erythropoietin (EPO) and its analogs induce cytoprotective effects on many nonerythroid cells. In this study, we examined whether darbepoetin-α might prevent glomerular lesions in the Thy-1.1 model of glomerulonephritis (Thy-1-GN). GN was induced in Wistar rats by a single injection of monoclonal anti-Thy-1.1 antibody. Rats were killed at 24 h, 72 h, 7 days, 10 days, or 15 days after antibody injection. Kidneys were removed for histological analysis, and proteinuria was measured. Because at day 7 the maximal degree of renal damage and proteinuria was found, the effect of darbepoetin-α was tested at day 7 and two different protocols of administration were used; After anti-Thy-1.1 injection, rats received two doses of darbepoetin-α or vehicle at days 0 and 4 or at days 4 and 6. At day 7, proteinuria, plasma creatinine concentration, and renal morphology analysis were performed. Also, α-actin, desmin, caspase-3, and Ki67 protein expression were evaluated by immunohistochemistry. Our results showed that in both protocols of administration, darbepoetin-α treatment decreased proteinuria in Thy-1-GN rats and this effect correlated with the improvement in renal morphology. Glomerular lesions, α-actin, and caspase-3 protein expression, observed in most glomeruli of Thy-1-GN rats, were significantly reduced in darbepoetin-α-treated rats, while cell proliferation was significantly enhanced. The results indicate that darbepoetin-α treatment promotes glomerular recovery.

Prevention of acute kidney injury and protection of renal function in the intensive care unit. Expert opinion of the Working Group for Nephrology, ESICM

BACKGROUND

Acute renal failure on the intensive care unit is associated with significant mortality and morbidity.

OBJECTIVES

To determine recommendations for the prevention of acute kidney injury (AKI), focusing on the role of potential preventative maneuvers including volume expansion, diuretics, use of inotropes, vasopressors/vasodilators, hormonal interventions, nutrition, and extracorporeal techniques.

METHOD

A systematic search of the literature was performed for studies using these potential protective agents in adult patients at risk for acute renal failure/kidney injury between 1966 and 2009. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, and use of potentially nephrotoxic drugs and radiocontrast media. Where possible the following endpoints were extracted: creatinine clearance, glomerular filtration rate, increase in serum creatinine, urine output, and markers of tubular injury. Clinical endpoints included the need for renal replacement therapy, length of stay, and mortality. Studies are graded according to the international Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) group system.

CONCLUSIONS AND RECOMMENDATIONS

Several measures are recommended, though none carries grade 1A. We recommend prompt resuscitation of the circulation with special attention to providing adequate hydration whilst avoiding high-molecular-weight hydroxy-ethyl starch (HES) preparations, maintaining adequate blood pressure using vasopressors in vasodilatory shock. We suggest specific vasodilators [corrected] under strict hemodynamic control, sodium bicarbonate for emergency procedures administering contrast media, and periprocedural hemofiltration in severe chronic renal insufficiency undergoing coronary intervention.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s00134-009-1678-y) contains supplementary material, which is available to authorized users.

Thrombopoietin limits IL-6 release but fails to attenuate liver injury in two hepatic stress models

OBJECTIVE

Various pleiotropic substances have been suggested as candidates that directly reduce the severity of liver injury after hepatic ischemia/reperfusion (I/R) and upon acute liver failure (ALF). Herein, we studied whether thrombopoietin (TPO), the main regulator of megakaryopoiesis and thrombopoiesis, showed hepatoprotective effects and might mediate an antiapoptotic function in liver tissue under stress.

METHODS/RESULTS

In livers with ALF or undergoing warm hepatic I/R, injury was quantified by intravital fluorescence microscopy, chemical, and immunohistochemical analysis as well as western immunoblot. Induction of both ALF and I/R injury led to hepatocellular expression of c-mpl, the receptor of TPO. Exogenous application of recombinant TPO in a low (12.5 microg/kg) as well as a high (75 microg/kg) dose, however, did not ameliorate postischemic perfusion and leukocyte endothelial cell interaction, but slightly aggravated transaminase release upon I/R. Similarly, TPO was unable to dampen hepatic microcirculatory deteriorations after the induction of ALF, but caused an increase of leukocyte accumulation and transaminase activity when applied in high dose. Low dose of TPO did not influence the amount of hepatocellular apoptosis, whereas high-dose TPO slightly diminished the activation of caspase 3. Interestingly, exogenous TPO application completely reversed the stress-induced increase of plasma IL-6 levels, suggesting a negative feedback of TPO on IL-6 release.

CONCLUSION

Although the existence of the TPO-receptor on target liver cells TPO plays only a minor role in mediating hepatocyte apoptosis and does not provide protection against hepatic injury, contrasting the efficacy of the related hematopoietic growth factor erythropoietin.

Chronic treatment with recombinant human erythropoietin exerts renoprotective effects beyond hematopoiesis in streptozotocin-induced diabetic rat

Recombinant human erythropoietin (rHuEPO), which has been used clinically for the management of renal anemia, is reported to exert pleiotropic beneficial properties against acute ischemic/reperfusion injury in various tissues. To investigate the hypothesis that chronic treatment with rHuEPO might ameliorate diabetic nephropathy beyond hematopoiesis, rHuEPO (150 U/kg, subcutaneously) was administered three times per week to the streptozotocin-induced diabetic rats for 4 weeks. Streptozotocin (65 mg/kg, intravenously) significantly increased urinary protein excretion and collagen deposition in glomerular and tubulointerstitial areas in the kidney, which were attenuated by rHuEPO. rHuEPO normalized the levels of creatinine clearance, serum creatinine, and blood urea nitrogen of diabetic rats. RT-PCR analysis revealed that the expressions of mRNA for transforming growth factor-beta, osteopontin and adhesion molecules were enhanced in the diabetic rat kidney and that the overexpression of these molecules was suppressed by rHuEPO. rHuEPO exerted antioxidant properties by inhibiting renal activation and overexpression of NADPH oxidase. We found the activation of the Akt signaling pathway by the increased expression of phosphorylated Akt and GSK-3beta and a reduction of TUNEL-positive apoptotic cell death in renal tissue from rHuEPO-treated diabetic group. We also demonstrated that rHuEPO restored the endothelial nitric oxide synthase (eNOS) content in the diabetic rat kidney. On the other hand, treatment with rHuEPO did not affect blood glucose level, blood pressure, or hematocrit in diabetic rats. These results suggest that chronic treatment with rHuEPO attenuated renal injury beyond hematopoiesis and regulated apoptosis and eNOS expression, which might be due to the activation of Akt pathway.

Two large preoperative doses of erythropoietin do not reduce the systemic inflammatory response to cardiac surgery

OBJECTIVES

Cardiac surgery and cardiopulmonary bypass (CPB) induce an inflammatory reaction that may lead to tissue injury. Experimental studies suggest that recombinant human erythropoietin (EPO) independent of its erythropoietic effect may be used clinically as an anti-inflammatory drug. This study tested the hypothesis that 2 large doses of EPO administered shortly before CPB ameliorate the systemic inflammatory response to CPB.

DESIGN AND SETTING

A prospective, double-blind, placebo-controlled and randomized study at a single tertiary care hospital.

PARTICIPANTS

Patients scheduled for coronary artery bypass graft surgery with CPB.

INTERVENTIONS

EPO (epoetin alfa, 500 IU/kg intravenously, n = 22) or placebo (n = 21) was administered 12 to 18 hours preoperatively and again at the induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

CPB in both groups greatly increased plasma concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-1beta receptor antagonist, IL-6, IL-10, and N-terminal probrain natriuretic peptide (NT-proBNP). Compared with placebo, EPO at day 3 after CPB augmented the TNF-alpha response (p < 0.05) and at 2 hours after CPB increased NT-proBNP (p < 0.05). Also, EPO tended to enhance the CPB-induced increase in IL-1beta receptor antagonist (p = 0.057). Otherwise, EPO had no effect on pro- and antiinflammatory mediators compared with placebo.

CONCLUSIONS

Two large doses of EPO given shortly before CPB do not reduce perioperative release of inflammatory cytokines. In contrast, EPO may augment the TNF-alpha and NT-proBNP response. Although the long-term clinical impact remains unknown, the findings do not support use of EPO as an anti-inflammatory drug in patients undergoing cardiac surgery.

Acute kidney injury and chronic kidney disease after cardiac surgery

Kidney dysfunction is common after cardiac surgery and predicts mortality risk and poorer long-term outcome, particularly when acute injury superimposes upon chronic kidney disease. Numerous insults contribute to perioperative renal impairment including major surgical trespass, procedure-specific interventions (eg, deep hypothermic circulatory arrest), and postoperative complications. Regardless of cause, evidence supports a role for renal impairment and accumulation of "uremic toxins" as direct contributors to adverse outcome. No one has yet characterized a loss of renal function small enough to be insignificant. Despite considerable research focus, progress in development of interventions aimed at perioperative renoprotection has been disappointing. However, practice modifications can influence the likelihood of acute kidney injury, and several recent advances provide hope for the future. We review pathophysiologic understanding of this disorder; evaluate the confusing relationship (causal v epiphenomena) among acute kidney injury, chronic kidney disease, and adverse outcome after cardiac surgery; and provide an evidence-based assessment of the conduct of cardiac surgery and renoprotection strategies.

Induction of hypoxia-inducible factor 1alpha gene expression by vascular endothelial growth factor

Transcriptional regulation of vascular endothelial growth factor (VEGF) is critically dependent on hypoxia-inducible factor 1 (HIF-1). However, not only hypoxia, but selected growth factors can induce HIF-1. High levels of both VEGF and HIF-1 coexist in certain conditions, e.g. tumors. Nonetheless, the possibility that the stimulatory relationship between HIF-1 and VEGF may be bi-directional has not been addressed up to date. The present study in endothelial cells analyzed whether HIF-1 is regulated by a product of its own transcriptionally activated genes, namely, VEGF. As a main finding, VEGF-A(165) induced the increase of HIF-1alpha mRNA and HIF-1alpha protein and nuclear translocation. Autologous endothelial cell VEGF mRNA and protein were also increased upon exposure to exogenous VEGF. The signaling implication of reactive oxygen species was examined by comparison with H(2)O(2) and hypoxanthine/xanthine oxidase and by the superoxide dismutase mimetic, MnTMPyP, the Rac1-NAD(P)H oxidase complex inhibitor, apocynin, transfection of a dominant negative Rac1 mutant, and transfection of a p67phox antisense oligonucleotide. Superoxide anion, largely dependent on Rac1-NAD(P)H oxidase complex activity, was the critical signaling element. The transductional functionality of the pathway was confirmed by means of a reporter gene flanked by a transcription site-related VEGF sequence and by quantitative PCR. In summary, the present results reveal a previously undescribed action of VEGF on the expression of its own transcription factor, HIF-1, and on VEGF itself. This effect is principally mediated by superoxide anion, therefore identifying a new, potentially relevant role of reactive oxygen species in VEGF signaling.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Selective modulation of the erythropoietic and tissue-protective effects of erythropoietin: time to reach the full therapeutic potential of erythropoietin

Erythropoietin (EPO) has been used clinically both as an erythropoietic stimulating agent in the treatment of anemia and as a tissue-protective agent in diverse clinical settings including stroke, multiple sclerosis, acute myocardial infarction and others. However, use of EPO or EPO-analogues leads to simultaneous targeting of both the erythropoietic and tissue-protective properties of EPO, and this strategy has been associated with several problems. Specifically, the benefit of correction of cancer-related anemia can be offset by the tissue-protective effects of EPO, which may lead to stimulation of cancer cell proliferation. Conversely, the benefit of tissue-protection in patients with stroke or myocardial infarction can be offset by adverse effects associated with the erythropoietic effects of EPO such as elevation of red blood cell mass, hypertension and prothrombotic phenomena. The finding that the erythropoietic and tissue-protective properties of EPO are conferred via two distinct receptor systems raises the interesting possibility of discovering novel drugs that selectively stimulate either the erythropoietic or the tissue-protective activities of EPO. This article reviews the current status of the clinical use of EPO and EPO-analogues in the treatment of cancer-related anemia and for tissue protection, outlines the distinct molecular biology of the tissue-protective and erythropoietic effects of EPO and discusses strategies of selective targeting of these activities with the goal of exploiting the full therapeutic potential of EPO.

Effect of early nephrology referral on the initiation of hemodialysis and survival in patients with chronic kidney disease and cardiovascular diseases

BACKGROUND

The timing of referral to nephrologists is highly variable in patients with chronic kidney disease (CKD). The impact of early referral on the timing of hemodialysis (HD) and mortality in the patients with CKD and cardiovascular diseases (CVD) was evaluated in this present study.

METHODS AND RESULTS

A total of 366 patients with CKD and CVD began HD at the National Cardiovascular Center between 1983 and 2003, and survival was followed until 2005. The times between the first evaluation by a nephrologist and the date of the first HD were categorized as late (LR <6 months) or early (ER > or =6 months) referral. Patients were classified into the ER (n=194) and LR (n=172) groups. Clinical data and renal function were not different. In the LR group, the renal function declined more rapidly and the duration between the first visit to the hospital and the first HD was shorter than the ER group. The survival rate after the initiation of HD was better in the ER group. Age, pre end-stage renal disease therapy and cardiac function had a significant impact on survival.

CONCLUSIONS

Early nephrology referral is important and necessary for for patients with CKD and CVD in terms of a better renal prognosis and survival.