Erythropoietin ameliorates oxidative stress and tissue injury following renal ischemia/reperfusion in rat kidney and lung

Anemia and Hypoxia Impact on Chronic Kidney Disease Onset and Progression: Review and Updates

Chronic kidney disease (CKD) is caused by hypoxia in the renal tissue, leading to inflammation and increased migration of pathogenic cells. Studies showed that leukocytes directly sense hypoxia and respond by initiating gene transcription, encoding the 2-integrin adhesion molecules. Moreover, other mechanisms participate in hypoxia, including anemia. CKD-associated anemia is common, which induces and worsens hypoxia, contributing to CKD progression. Anemia correction can slow CKD progression, but it should be cautiously approached. In this comprehensive review, the underlying pathophysiology mechanisms and the impact of renal tissue hypoxia and anemia in CKD onset and progression will be reviewed and discussed in detail. Searching for the latest updates in PubMed Central, Medline, PubMed database, Google Scholar, and Google search engines were conducted for original studies, including cross-sectional studies, cohort studies, clinical trials, and review articles using different keywords, phrases, and texts such as "CKD progression, anemia in CKD, CKD, anemia effect on CKD progression, anemia effect on CKD progression, and hypoxia and CKD progression". Kidney tissue hypoxia and anemia have an impact on CKD onset and progression. Hypoxia causes nephron cell death, enhancing fibrosis by increasing interstitium protein deposition, inflammatory cell activation, and apoptosis. Severe anemia correction improves life quality and may delay CKD progression. Detection and avoidance of the risk factors of hypoxia prevent recurrent acute kidney injury (AKI) and reduce the CKD rate. A better understanding of kidney hypoxia would prevent AKI and CKD and lead to new therapeutic strategies.

PRETREATMENT WITH ERYTHROPOIETIN ALLEVIATES THE RENAL DAMAGE INDUCED BY ISCHEMIA REPERFUSION VIA REPRESSION OF INFLAMMATORY RESPONSE

OBJECTIVE

The aim: This study aimed to examine the anti-inflammatory, and antiapoptotic effects of erythropoietin against kidney injury inducted by ischemia reperfusion in experimental model.

PATIENTS AND METHODS

Materials and methods: 20 male Sprague Dawley rats were randomly divided into 4 equal groups: sham (subject to median laparotomy only), control (subject to 30 minutes ischemia and 2hours reperfusion), vehicle (injected by distilled water and subjected to the same procedure of ischemia reperfusion), erythropoietin group (as in vehicle group but the rats pretreated with 1000 U/kg of erythropoietin). The left kidney and blood specimen were collected. The blood utilized to assess serum creatinine. While kidneys utilized to assessed MCP-1, TLR2, and caspase-3 in addition to histopathological evaluation.

RESULTS

Results: Control and vehicle samples showed that a significant elevation in serum creatinine, TLR2, caspase-3, and MCP-1 as compared with sham group. The histological eval¬uation showed a significant rise in kidney injury scores. Kidneys and blood samples of erythropoietin pretreated rats established histopathological and functional improvement as evidenced via reduced kidney injury scores in addition to the reduction in serum creatinine, as well as there were a significant diminished in caspase-3, MCP-1, and TLR2 levels when compared with control and vehicle groups.

CONCLUSION

Conclusions: Erythropoietin has renoprotective effect against ischemia and reperfusion, which achieved by decrease the inflammatory response as well as antiapoptotic effect.

Protective effect of Eprosartan against ischemic acute renal injury: Acting on NF-κB, caspase 3, and Sirtuin 1

Kidney ischemia/reperfusion (I/R) injury is a leading cause of acute kidney injury (AKI) occurring frequently under major surgeries and sepsis. This study aimed to evaluate the effect of Eprosartan, an angiotensin II receptor type-1 (AT-1) antagonist, on the kidney I/R rat model. Male Wistar rats (n = 24) were allocated into (i) Sham, (ii) Eprosartan, (iii) I/R, and (iv) Eprosartan + I/R groups. Animals in the last group received a single dose of Eprosartan (60 mg/kg) 1 h before kidney I/R. Renal oxidant/antioxidant, inflammatory (NF-κB p65, COX-2, IL-6, TNF-α), and apoptotic (caspase-3, Bax, Bcl2) factors along with Sirtuin 1, Klotho, and mitochondrial biogenesis (PGC-1α, and Sirtuin 3) factors were evaluated by Western blotting. Significant recovery of kidney function and increased levels of antioxidant markers were observed in the Eprosartan + I/R group. The Eprosartan anti-inflammatory activity was demonstrated by significant downregulation of NF-κB and its downstream pro-inflammatory factors. Eprosartan pretreatment could also abolish I/R-induced alterations in the apoptotic parameters. Moreover, Eprosartan + I/R rats significantly presented higher levels of Sirtuin 1 content. In conclusion, Eprosartan exhibited nephroprotective effects against kidney damage induced by I/R in rats by decreasing oxidative stress, inflammatory, and apoptotic pathways along with increasing Sirtuin1 level.

Eplerenone reduces renal ischaemia/reperfusion injury by modulating Klotho, NF-κB and SIRT1/SIRT3/PGC-1α signalling pathways

OBJECTIVES

Acute kidney injury (AKI) is a sudden impairment in kidney function that is associated with high morbidity and mortality. Inflammation, oxidative stress, mitochondrial impairment and energy depletion, along with organ dysfunction are hallmarks of AKI. This study aimed to evaluate the effects of Eplerenone, an aldosterone receptor antagonist, on the kidney injury caused by ischaemia/reperfusion (I/R).

METHODS

Male Wistar rats (n = 24) were randomly allocated into four groups: sham, IR, Eplerenone and Eplerenone+IR. Rats in the two last groups 1 h before I/R induction, were treated with Eplerenone (100 mg/kg) via intraperitoneal injection. Protein levels of Klotho, heat shock protein 70 (HSP70), sirtuin1 (SIRT1), SIRT3 and peroxisome proliferator-activated receptor-gamma coactivator 1-α (PGC-1α) along with antioxidant, apoptotic (caspase 3, Bax and Bcl2) and inflammatory [nuclear factor kappa-B (NF-κB) p65, Interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2)] factors were evaluated in the kidney tissues of the experimental groups.

KEY FINDINGS

Eplerenone pre-treatment significantly could improve IR-induced pathological changes and kidney function and increase the renal antioxidant factors compared to the IR group (P < 0.05). Furthermore, in the Eplerenone + IR group, significant elevation of the Klotho, SIRT1, SIRT3 and PGC-1α at the protein level was identified compared to the IR group. Eplerenone pretreatment could not only downregulate NF-κB signalling and its downstream inflammatory factors (IL-6, COX-2 and TNF-α) but also could decrease apoptotic factors (P ≤ 0.01).

CONCLUSIONS

The results recommended that Eplerenone exerts a protective effect against kidney IR injury by up-regulating Klotho, HSP70, sirtuins and PGC-1α to preserve mitochondrial function and cell survival. Moreover, it hinders renal inflammation by suppressing NF-κB signalling. These results offer insight into the prevention or treatment of AKI in the future.

Histological and immunohistochemical study of the effect of ozone versus erythropoietin on induced skeletal muscle ischemia-reperfusion injury in adult male rats

Ischemia reperfusion (IR) injury of skeletal muscles is a serious problem because of its local and systemic complications. Previous studies reported that ozone and erythropoietin could alleviate IR effect on several organs. The current research is established to evaluate the possible protective role of ozone versus erythropoietin following IR injury of the gastrocnemius muscle. Fifty rats were equally divided into five groups: I control, II ischemia reperfusion (IR), III post-reperfusion ozone treated, IV post-reperfusion erythropoietin-treated, and V recovering post-reperfusion without treatment groups. The right femoral arteries of all rats were clamped for three hours to induce ischemia then clamps were released to allow reperfusion for two hours. Rats of group II were scarified immediately after reperfusion period. Rats of group III were injected with ozone just after reperfusion for 14 days. Animals of group IV were injected with erythropoietin just after reperfusion for 14 days. Rats of group V rats were kept for 2 weeks following reperfusion without treatment. Blood samples were obtained to estimate lactate dehydrogenase (LDH) and creatine kinase (CK) enzymes. Gastrocnemius muscle was processed for measurement of tissue malondialdehyde (MDA), as well as examination by light and electron microscopes. iNOS and PCNA immunohistochemistry and statistical analysis were applied. The current results indicated that both ozone and erythropoietin could be used as protective agents reducing the muscular damage induced by IR injury.

Assessment of Oxidative Stress Markers in Hypothermic Preservation of Transplanted Kidneys

Ischemia-reperfusion injury (IRI) after renal transplantation is a complex biochemical process. The first component is an ischemic phase during kidney storage. The second is reperfusion, the main source of oxidative stress. This study aimed to analyze the activity of enzymes and concentrations of non-enzymatic compounds involved in the antioxidant defense mechanisms: glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione transferase (GST), thiobarbituric acid reactive substances (TBARS), malondialdehyde (MDA), measured in preservation fluid before transplantation of human kidneys (KTx) grafted from brain dead donors. The study group (N = 66) was divided according to the method of kidney storage: Group 1—hypothermic machine perfusion (HMP) in LifePort perfusion pump, n1 = 26, and Group 2—static cold storage (SCS), n2 = 40. The measurements of kidney function parameters, blood count, and adverse events were performed at constant time points during 7-day hospitalization and 3-month follow-up. Kidney perfusate in Group 2 was characterized by significantly more acidic pH (p < 0.0001), higher activity of GPX [U/mgHb] (p < 0.05) and higher concentration of MDA [μmol/L] (p < 0.05). There was a statistically significant improvement of kidney function and specific blood count alterations concerning storage method in repeated measures. There were aggregations of significant correlations (p < 0.05) between kidney function parameters after KTx and oxidative stress markers: diuresis & CAT, Na⁺ & CAT, K⁺ & GPX, urea & GR. There were aggregations of significant correlations (p < 0.05) between recipient blood count and oxidative stress markers: CAT & MON, SOD & WBC, SOD & MON. Study groups demonstrated differences concerning the method of kidney storage. A significant role of recipient’s gender, gender matching, preservation solution, and perfusate pH was not confirmed, however, basing on analyzed data, the well-established long-term beneficial impact of HMP on the outcome of transplanted kidneys might partially depend on the intensity of IRI ischemic phase and oxidative stress, reflected by the examined biomarkers.

Cytoprotective effects of erythropoietin: What about the lung?

Erythropoietin (Epo) is a pleiotropic cytokine, essential for erythropoiesis. Epo and its receptor (Epo-R) are produced by several tissues and it is now admitted that Epo displays other physiological functions than red blood cell synthesis. Indeed, Epo provides cytoprotective effects, which consist in prevention or fight against pathological processes. This perspective article reviews the various protective effects of Epo in several organs and tries to give a proof of concept about its effects in the lung. The tissue-protective effects of Epo could be a promising approach to limit the symptoms of acute and chronic lung diseases.

Nephrotoxicity and possible mechanisms of decabrominated diphenyl ethers (BDE-209) exposure to kidney in broilers

The flame retardant decabrominated diphenyl ether (BDE-209) is a widely used chemical in a variety of products and exists extensively in the environment. BDE-209 has been reported to induce kidney injury and dysfunction. However, the causes and mechanisms of its nephrotoxicity are still under investigation. In this study, 150 male broilers were exposed to BDE-209 concentrations of 0, 0.004, 0.04, 0.4, 4.0 g/kg for 42 days. The relative kidney weight, histopathology, markers of renal injury, oxidative stress, inflammation, apoptosis and the expression of MAPK signaling pathways-related proteins were assessed. The results showed that the concentrations of blood urea nitrogen (BUN), creatinine (CRE) and the neutrophil gelatinase-associated lipocalin (NGAL), significantly increased after exposure to BDE-209 with the doses more than 0.04 g/kg. Similarly, severe damage of renal morphology was observed, including atrophy and necrosis of glomeruli, and swelling and granular degeneration of the renal tubular epithelium. In the renal homogenates, the oxidative stress was evidenced by the elevated concentrations of MDA and NO, and decreased levels of GSH-Px, GSH and SOD. Due to the inflammatory response, the level of NF-κB and the pro-inflammatory cytokines TNF-α, IL-1β, IL-18 were remarkably upregulated, while the content of the anti-inflammatory cytokine IL-10 decreased. Additionally, the apoptotic analysis showed notable upregulations of Bax/Bcl-2 ratio, the relative expression of p-ERK1/2 and p-JNK1/2, and the expression of Bax, cytochrome c and caspase 3. The present study indicates that BDE-209 exposure can cause nephrotoxicity in broilers through oxidative stress and inflammation, which activate the phosphorylation of key proteins of the MAPK signaling pathways, and subsequently induce mitochondria-mediated kidney apoptosis.

Intranasal injection of recombinant human erythropoietin improves cognitive and visual impairments in chronic cerebral ischemia rats

The present study aimed to study the protective effect of intranasally delivered recombinant human erythropoietin (rhEPO) on cognitive and visual impairments in a permanent bilateral common carotid artery occlusion (2VO)-induced chronic cerebral ischemia (CCI) rat model. Male Sprague-Dawley rats (age, 6 months) with 2VO-induced CCI were treated with intranasal rhEPO (50 U/100 g) once per week for 8 weeks. A Morris water maze was used to evaluate the spatial learning and memory of the rats. Flash visual evoked potentials were measured to assess retinal function. Hematoxylin and eosin staining was performed to visualize and evaluate histopathological changes in the cerebral cortex, the hippocampus CA1 region and the retina. CCI-induced learning, memory and visual impairments were significantly alleviated in rats treated with rhEPO compared with those treated with a saline vehicle control. This was evidenced by remarkably decreased escape latency, increased frequency of crossing the hidden platform and elevated amplitude of primary wave in the rats treated with rhEPO. In addition, the rats experienced CCI-induced histopathological alterations, demonstrated by thinning of the cerebral cortex and retina, and losses of neurons and retinal ganglion cells. These alterations were significantly reversed in response to rhEPO administration compared with the saline vehicle control group. rhEPO may exert a protective role against cognitive and visual impairments in rats with CCI at least partially through preventing the thinning of the cerebral cortex and retina, as well as by inhibiting the loss of neurons and retinal ganglion cells.

Penehyclidine hydrochloride inhibits renal ischemia/reperfusion-induced acute lung injury by activating the Nrf2 pathway

The nuclear factor (NF)-κB and NOD-like receptor protein 3 (NLRP3) pathways promote inflammatory signaling that injures the kidneys, whereas the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway promotes anti-inflammatory signaling that inhibits oxidative damage. Penehyclidine hydrochloride (PHC) inhibits NF-κB and activates Nrf2 signaling. We investigated whether PHC induces communication between the Nrf2 and NF-κB/NLRP3 pathways, thereby protecting against renal ischemia/reperfusion (rI/R)-induced lung inflammation. Rat alveolar macrophages (NR8383 cells) were stimulated for 24 h with PHC with or without brusatol (a Nrf2 antagonist), after which they were treated for 4 h with tert-butyl hydroperoxide (10 mM). PHC Nrf2-dependently alleviated tert-butyl hydroperoxide-induced reactive oxygen species production in alveolar macrophages. Additionally, wild-type and Nrf2^-/- rats were each divided into four groups: (1) sham, (2) PHC (1 mg/kg), (3) rI/R and (4) rI/R + PHC (1 mg/kg). PHC markedly induced the Nrf2 and adenosine monophosphate-activated protein kinase pathways and suppressed rI/R-induced NF-κB and NLRP3 activation in the lungs. Nrf2 deficiency diminished the ability of PHC to ameliorate rI/R-induced histopathological alterations and reactive oxygen species release in the lungs; however, PHC inhibited NLRP3 signaling Nrf2-dependently, while it inhibited NF-κB signaling Nrf2-independently. Our findings demonstrate the beneficial effects of PHC on rI/R-induced lung inflammation.

Pregnancy protects the kidney from acute ischemic injury

A complex analysis of acute kidney injury (AKI) in pregnant women shows that it is caused by the interaction of gestation-associated pathologies and beneficial signaling pathways activated by pregnancy. Studies report an increase in the regeneration of some organs during pregnancy. However, the kidney response to the injury during pregnancy has not been addressed. We investigated the mechanisms of the pregnancy influence on AKI. During pregnancy, the kidneys were shown to be more tolerant to AKI. Pregnant animals showed remarkable preservation of kidney functions after ischemia/reperfusion (I/R) indicated by the decrease of serum creatinine levels. The pregnant rats also demonstrated a significant decrease in kidney injury markers and an increase in protective markers. Two months after the I/R, group of pregnant animals had a decreased level of fibrosis in the kidney tissue. These effects are likely linked to increased cell proliferation after injury: using real-time cell proliferation monitoring we demonstrated that after ischemic injury, cells isolated from pregnant animal kidneys had higher proliferation potential vs. control animals; it was also supported by an increase of proliferation marker PCNA levels in kidneys of pregnant animals. We suggest that these effects are associated with hormonal changes in the maternal organism, since hormonal pseudopregnancy simulated effects of pregnancy.

Comparison of the excretory capacities of erythropoietin and U-74389G concerning serum creatinine levels

Introduction This study compared the excretory effects, the erythropoietin (Epo) and antioxidant drug U-74389G exert on serum creatinine levels through kidneys. 2 preliminary studies were used for this purpose including respectively one drug used in a renal ischemia–reperfusion (IR) protocol of an animal model. The preliminary studies are part of the present work. The subjects were pretreated in preliminary studies but the results of the same subjects were simply compared in the current work.

Materials and methods The serum creatinine levels were evaluated at the 60th reperfusion min (for groups A, C and E) and at the 120th reperfusion min (for groups B, D and F) after IR in the 60 rats. Groups A and B received no drugs, rats from groups C and D were administered with Epo, whereas rats from groups E and F were administered with U-74389G.

Results The first preliminary study recommended a non-significant excretory effect of Epo (p-value = 0.4430 > 0.05) than placebo for serum creatinine levels. The second preliminary study proved a very significant excretory effect of U-74389G (p-value = 0.0005 < 0.05) than placebo for serum creatinine levels. These 2 studies were co-evaluated since they came from the same experimental setting. The outcome of the co-evaluation was that U-74389G has at least 5-fold significant excretory action (p-value = 0.0000 < 0.05) than Epo for serum creatinine levels.

Conclusions The U-74389G presents surprising effective excretory potencies for serum creatinine levels maybe of great importance in hemodialysis patients.

Alternative Erythropoietin Receptors in the Nervous System

In addition to its regulatory function in the formation of red blood cells (erythropoiesis) in vertebrates, Erythropoietin (Epo) contributes to beneficial functions in a variety of non-hematopoietic tissues including the nervous system. Epo protects cells from apoptosis, reduces inflammatory responses and supports re-establishment of compromised functions by stimulating proliferation, migration and differentiation to compensate for lost or injured cells. Similar neuroprotective and regenerative functions of Epo have been described in the nervous systems of both vertebrates and invertebrates, indicating that tissue-protective Epo-like signaling has evolved prior to its erythropoietic function in the vertebrate lineage. Epo mediates its erythropoietic function through a homodimeric Epo receptor (EpoR) that is also widely expressed in the nervous system. However, identification of neuroprotective but non-erythropoietic Epo splice variants and Epo derivatives indicated the existence of other types of Epo receptors. In this review, we summarize evidence for potential Epo receptors that might mediate Epo's tissue-protective function in non-hematopoietic tissue, with focus on the nervous system. In particular, besides EpoR, we discuss three other potential neuroprotective Epo receptors: (1) a heteroreceptor consisting of EpoR and common beta receptor (βcR), (2) the Ephrin (Eph) B4 receptor and (3) the human orphan cytokine receptor-like factor 3 (CRLF3).

Erythropoietin mediates brain-vascular-kidney crosstalk and may be a treatment target for pulmonary and resistant essential hypertension

Organ crosstalk pathways represent the next frontier for target-mining in molecular medicine for existing syndromes. Pulmonary hypertension and resistant essential hypertension are syndromes that have been proven elusive in etiology, and frequently refractory to first-line management. Underlying crosstalk mechanisms, not yet considered in these treatments, may hinder outcomes or unlock novel treatments. This review focuses systematically on erythropoietin, a synthesizable molecule, as a mediator of brain-kidney crosstalk. Insights gained from this review will be applied to cardiovascular diseases in a clinician-directed fashion.

Identification of methionine oxidation in human recombinant erythropoietin by mass spectrometry: Comparative isoform distribution and biological activity analysis

BACKGROUND

Oxidative degradation of human recombinant erythropoietin (hrEPO) may occur in manufacturing process or therapeutic applications. This unfavorable alteration may render EPO inefficient or inactive. We investigated the effect of methionine/54 oxidative changes on the amino acid sequences, glycoform distribution and biological activity of hrEPO.

METHODS

Mass spectrometry was applied to verify the sequence and determine the methionine oxidation level of hrEPO. Isoform distribution was studied by capillary zone electrophoresis method. In vivo normocythemic mice assay was used to assess the biological activity of three different batches (A, B, and C) of the proteins.

RESULTS

Nano-LC/ESI/MS/MS data analyses confirmed the amino acid sequences of all samples. The calculated area percent of three isoforms (2-4 of the 8 obtained isoforms) were decreased in samples of C, B, and A with 27.3, 16.7, and 6.8% of oxidation, respectively. Specific activities were estimated as 53671.54, 95826.47, and 112994.93 mg/mL for the samples of A, B, and C, respectively.

CONCLUSION

The observed decrease in hrEPO biological activity, caused by increasing methionine oxidation levels, was rather independent of its amino acid structure and mainly associated with the higher contents of acidic isoforms.

Mitochondria-targeted antioxidant MitoQ reduced renal damage caused by ischemia-reperfusion injury in rodent kidneys: Longitudinal observations of T2 -weighted imaging and dynamic contrast-enhanced MRI

Purpose

To investigate the effect of mitochondria‐targeted antioxidant MitoQ in reducing the severity of renal ischemia‐reperfusion injury (IRI) in rats using T₂‐weighted imaging and dynamic contrast‐enhanced MRI (DCE‐MRI).

Methods

Ischemia‐reperfusion injury was induced by temporarily clamping the left renal artery. Rats were pretreated with MitoQ or saline. The MRI examination was performed before and after IRI (days 2, 5, 7, and 14). The T₂‐weighted standardized signal intensity of the outer stripe of the outer medulla (OSOM) was measured. The unilateral renal clearance rate k_cl was derived from DCE‐MRI. Histopathology was evaluated after the final MRI examination.

Results

The standardized signal intensity of the OSOM on IRI kidneys with MitoQ were lower than those with saline on days 5 and 7 (P = 0.004, P < 0.001, respectively). K_cl values of IRI kidneys with MitoQ were higher than those with saline at all time points (P = 0.002, P < 0.001, P = 0.001, P < 0.001). Histopathology showed that renal damage was the most predominant on the OSOM of IRI kidneys with saline, which was less obvious with MitoQ (P < 0.001).

Conclusions

These findings demonstrate that MitoQ can reduce the severity of renal damage in rodent IRI models using T₂‐weighted imaging and DCE‐MRI. Magn Reson Med 79:1559–1667, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Erythropoietin Receptor Activation Protects the Kidney From Ischemia/Reperfusion-Induced Apoptosis by Activating ERK/p53 Signal Pathway

BACKGROUND

Apoptosis plays an important role in renal ischemia/reperfusion (IR) injury. Evidence has shown that erythropoietin (EPO) has an antiapoptotic effect. Therefore, this study aimed to explore the effect and potential mechanism of EPO in renal IR injury.

METHODS

Kidney IR injury in rats was established by clamping the left renal artery for 30 minutes followed by 24 hours of reperfusion, along with contralateral nephrectomy. Renal function, renal histology, and expression of EPOR, p-EPOR, ERK, p-ERK, p-p53, p53, Bcl-2, Bcl-xl, Bad, and Bax were examined.

RESULTS

Pretreatment with EPO significantly reduced renal dysfunction, pathologic change, and expression of Bad and Bax. Furthermore, EPO treatment enhanced the expression of p-ERK, p-p53, Bcl-2, and Bcl-xl with no influence on the expression of EPOR, ERK, and p53.

CONCLUSIONS

These findings demonstrated that EPO pretreatment can attenuate renal IR injury by inhibiting apoptosis by promoting activation of the ERK/p53 signaling.

Association of interleukin 18-607A/C and -137C/G polymorphisms with oxidative stress in renal transplant recipients

Objectives IL-18 mediates various inflammatory and oxidative responses including renal injury, fibrosis, and graft rejection. It has been reported that the promoter -607 and -137 polymorphisms of IL-18 influence the level of IL-18. This prospective observational study investigated the association between oxidative stress with IL-18-607 and -137 polymorphisms in renal transplant recipients. Patients and methods This study included 75 renal transplant recipients (28 female, 47 male) from living-related donors. Blood samples were collected immediately before and after transplantation at day 7 and month 1. Serum IL-18, creatinine, cystatin C, CRP, and oxidative stress markers (TOS, TAC) were measured. The Oxidative Stress Index (OSI) was calculated. Polymorphisms of the promoter region of the IL-18 gene, IL18-607A/C, and -137C/G were determined by analysis of a "real-time PCR/Melting curve". Results Serum creatinine, cystatin C, CRP, IL-18, TOS, and OSI levels significantly decreased after transplantation. Post-transplant levels of serum TAC and estimated GFR demonstrated consistent significant increases. Serum IL-18 levels were significantly higher in patients with IL-18-137 GG and IL-18-607 CC genotypes before transplantation. Conclusion Our results indicate that the IL-18-137 GG and -607 CC genotypes contribute to higher IL-18 levels; however, the influence of these polymorphisms on oxidative stress has not been observed.

Hypoxia: The Force that Drives Chronic Kidney Disease

In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy.

Erythropoietin pretreatment ameliorates renal ischaemia-reperfusion injury by activating PI3K/Akt signalling

AIM

Renal ischaemia-reperfusion (I/R) injury, a primary cause of acute renal failure, can induce high morbidity and mortality. This study aimed to explore the effect of erythropoietin on renal I/R injury and its underlying mechanism.

METHODS

Fifty male Sprague-Dawley rats were randomly allocated to three groups (n = 10): the sham group, the renal ischaemia-reperfusion-saline (IRI) group, and the IRI+-Erythropoietin (EPO) group. Erythropoietin (250, 500, 1000 U/kg) was intraperitoneally injected 30 min before inducing I/R. Renal I/R injury were induced by clamping the left renal artery for 30 min followed by reperfusion, along with a contralateral nephrectomy. Renal function and histological damage were determined after 24 h reperfusion. The expression of pro-inflammatory cytokines interleukin-6 (IL-6), interleukin-1 β (IL-1β), and tumour necrosis factor-α (TNF-α) in the serum and renal tissue were evaluated by enzyme linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Further, the effects of erythropoietin on PI3K/Akt signalling, erythropoietin receptor (EPOR) and nuclear factor (NF)-κB activation were measured by Western blotting.

RESULTS

Erythropoietin pretreatment can significantly decrease the level of renal dysfunction in a dose-dependent manner, attenuated the renal histological changes, the expression of TNF-α, IL-1β, and IL-6, the levels of reactive oxygen species (ROS) production and NF-κB p65 phosphorylation in renal tissue upon IRI. Moreover, erythropoietin pretreatment could further activate the PI3K/Akt signalling and induced EPOR activity.

CONCLUSIONS

Erythropoietin pretreatment could attenuate renal I/R injury by suppressing inflammation, which was associated with activating PI3K/Akt signalling though EPOR activation. Our findings suggest that erythropoietin may be a novel practical strategy to prevent renal I/R injury.

Ameliorative Effect of Recombinant Human Erythropoietin and Ischemic Preconditioning on Renal Ischemia Reperfusion Injury in Rats

Background:

Ischemia-reperfusion (IR) injury is one of the most common causes of renal dysfunction. There is increasing evidence about the role of the reactive oxygen species (ROS) in these injuries and endogenous antioxidants seem to have an important role in decreasing the renal tissue injury.

Objectives:

The aim of this study was to compare the effect of recombinant human erythropoietin (EPO) and ischemic preconditioning (IPC) on renal IR injury.

Materials and Methods:

Twenty four male Wistar rats were allocated into four experimental groups: sham-operated, IR, EPO + IR, and IPC + IR. Rats were underwent 50 minutes bilateral ischemia followed by 24 hours reperfusion. Erythropoietin (5000 IU/kg, i.p) was administered 30 minutes before onset of ischemia. Ischemic preconditioning was performed by three cycles of 3 minutes ischemia followed by 3 minutes reperfusion. Plasma concentrations of urea and creatinine were measured. Kidney samples were taken for reactive oxidative species (ROS) measurement including superoxide dismutase (SOD) activity, glutathione (GSH) contents, and malondialdehyde (MDA) levels.

Results:

Compared to the sham group, IR led to renal dysfunction as evidenced by significantly higher plasma urea and creatinine. Treatment with EPO or IPC decreased urea, creatinine, and renal MDA levels and increased SOD activity and GSH contents in the kidney.

Conclusions:

Pretreatment with EPO and application of IPC significantly ameliorated the renal injury induced by bilateral renal IR. However, both treatments attenuated renal dysfunction and oxidative stress in kidney tissues. There were no significant differences between pretreatment with EPO or application of IPC.

Benefits of the antioxidant and anti-inflammatory activity of etoricoxib in the prevention of ovarian ischemia/reperfusion injury induced experimentally in rats

AIM

This study is a biochemical investigation of the effect of etoricoxib, a selective cyclooxygenase (COX)-2 inhibitor, on ischemia/reperfusion (I/R) injury experimentally induced in rat ovaries.

METHODS

Experimental animals were divided into four groups: (i) ovarian ischemia/reperfusion (IRG); (ii) 30 mg/kg etoricoxib + ovarian ischemia/reperfusion (EIRG-30); (iii) 60 mg/kg etoricoxib + ovarian ischemia/reperfusion (EIRG-60); and (iv) a sham operation (SG) control group.

RESULTS

The results showed levels of malondialdehyde in the IRG, EIRG-30, EIRG-60 and SG group ovarian tissue of 20.2 ± 3.4, 11.2 ± 3.2, 5.5 ± 1.9 and 3.8 ± 1.5 μmol/g protein, respectively. Myeloperoxidase activity for these groups was 24.2 ± 6.7, 13 ± 2.4, 4 ± 1.8 and 3.5 ± 1.9 U/g protein, and total glutathione levels were 1.6 ± 0.8, 4.5 ± 1.9, 6.5 ± 1.9 and 7.5 ± 2.4 nmol/g protein, respectively. COX-1 activity in IRG, EIRG-30, EIRG-60 and SG group rat ovarian tissue was 5.0 ± 2.8, 12.2 ± 2.4, 16.7 ± 2.8 and 17.5 ± 4.7 U/mg protein, and COX-2 activity was 18.3 ± 2.7, 3.5 ± 1, 1.8 ± 0.7 and 0.7 ± 0.3 U/mg protein, respectively.

CONCLUSION

Etoricoxib prevented oxidative damage induced with I/R in rat ovarian tissue. This property of etoricoxib suggests that it can be clinically beneficial in the prevention of damage that may arise with reperfusion by detorsion for the protection of the ovaries against torsion.

Saphenous Vein Graft Disease Is Associated with a Low Serum Erythropoietin Level

OBJECTIVE

To measure the serum erythropoietin (EPO) level in patients with saphenous vein grafts (SVGs) and to compare the EPO level in those with and without SVG disease.

SUBJECTS AND METHODS

The study included 85 consecutive patients with a history of coronary artery bypass graft surgery that underwent elective coronary angiography. Patients with >30% stenosis (diseased grafts) in at least one saphenous graft were included in group 1 (diseased group: n = 40), and group 2 (nondiseased group: n = 45) consisted of patients without diseased SVGs. The EPO level was measured using enzyme-linked immunosorbent assay (ELISA) using a commercially available ELISA kit; x03C7;2 test and independent samples t test were used where appropriate. Logistic regression was used for multivariate analysis.

RESULTS

There were not any significant differences in age, gender, or cardiovascular risk factors between the two groups except for increased triglyceride and low high-density lipoprotein levels in group 2. The EPO level was significantly higher in the nondiseased SVG group than in the diseased SVG group (25.5 ± 9.6 vs. 17.8 ± 6.8 mU ml-1, p = 0.002). Multivariate logistic regression analysis showed that the serum EPO level was an independent predictor of SVG disease (OR 1.14, 95% CI 1.06-1.24, p = 0.001).

CONCLUSION

In this study, SVG disease was associated with a low serum EPO level, suggesting that a low EPO level could be predictive of and contributes to the pathophysiology of SVG disease.

Oxidative stress in kidney transplantation: malondialdehyde is an early predictive marker of graft dysfunction

BACKGROUND

Oxidative stress is one of the most important components of the ischemia-reperfusion process after kidney transplantation (KTx) and increases with graft dysfunction.

METHODS

This prospective study was conducted on 40 consecutive KTx recipients to evaluate time-dependent changes in oxidative stress-related parameters within the first week after KTx and to assess their performance in predicting delayed graft function (DGF=dialysis requirement during initial posttransplant week) and graft function at 1 year. Blood samples were collected before (day 0) and after KTx (days 1, 2, 4, and 7). Total antioxidant capacity, plasma levels of malondialdehyde (MDA), and activities of glutathione peroxidase, glutathione reductase and superoxide dismutase were measured. Multivariable linear mixed and linear regression models, receiver-operating characteristic (ROC), and areas under ROC curves (AUC-ROC) were used.

RESULTS

At all time points after KTx, mean MDA levels were significantly higher in patients developing DGF (n=18). Shortly after KTx (8-12 hr), MDA values were higher in DGF recipients (on average, +0.16 μmol/L) and increased further on following day, contrasting with prompt functioning recipients. Day 1 MDA levels accurately predicted DGF (AUC-ROC=0.90), with a performance higher than SCr (AUC-ROC=0.73) and similar to cystatin C (AUC-ROC=0.91). Multivariable analysis revealed that MDA levels on day 7 represented an independent predictor of 1-year graft function. Antioxidant enzyme activities were not significantly changed during the study period and were not predictors of 1-year graft function.

CONCLUSIONS

Increased MDA levels on day 1 after KTx might be an early prognostic indicator of DGF, and levels on day 7 might represent a useful predictor of 1-year graft function.

Effect of erythropoietin on free radical oxidation and glycoprotein expression in platelets under conditions of chronic renal failure

A short-term open prospective study examined 62 patients at the terminal stage of chronic renal failure. The experimental group received erythropoietin in a total dose of about 40,000 U. The expression of glycoproteins IIb-IIIa, IIb, and Ib was enhanced, the content of LPO products was elevated, and SOD and catalase activities were reduced in platelets from patients with chronic renal failure. Administration of erythropoietin partially restored free radical oxidation and expression of glycoproteins IIb-IIIa, IIb, and Ib in platelets. A significant correlation was revealed between the expression of platelet receptors on the one hand, and content of LPO products and SOD and catalase activities, on the other hand.

Protective role of recombinant human erythropoietin in kidney and lung injury following renal bilateral ischemia-reperfusion in rat model

BACKGROUND

Acute kidney injury (AKI) has been recognized as one of the most complex clinical complications in modern medicine, and ischemia/reperfusion (I/R) injury is well-known as a main reason of AKI. In addition, AKI leads to important systemic consequences such as acute lung injury. This study was designed to investigate the role of erythropoietin (EPO) on kidney function makers and tissue damage; and lung endothelial permeability and lung water content (LWC) in bilateral renal I/R injury model in rats.

METHODS

Male Wistar rats were randomly divided into three groups of sham, I/R, and I/R treated with EPO (I/R + EPO) groups. The I/R and I/R + EPO groups were subjected to bilateral renal I/R injury; however, only the I/R + EPO group received EPO (500 IU/kg, i.p.) 2 h before ischemia surgery, and the same dose was continued once a day for 3 days after ischemia. The sham group underwent a surgical procedure without ischemia process.

RESULTS

The blood urea nitrogen (BUN) and serum creatinine (Cr) levels, kidney tissue damage score (KTDS), and kidney weight (KW) per 100 g body weight significantly increased in I/R group (P < 0.05). EPO administration decreased levels of BUN and Cr significantly (P < 0.05), and KTDS and KW insignificantly (P = 0.1). No significant differences in kidney and serum levels of malondialdehyde, and lung vascular permeability and LWC were observed between the groups. The serum and kidney levels of nitrite were not significantly different between I/R and sham groups; however, administration of EPO increased the renal level of nitrite (P < 0.05).

CONCLUSIONS

EPO protected the kidney against I/R injury; however, it may not protect the lung tissue from the damage induced by renal I/R injury in rats.