Erythropoietin attenuated vascular dysfunction and inflammation by inhibiting NADPH oxidase-derived superoxide production in nitric oxide synthase-inhibited hypertensive rat aorta. Eur J Pharmacol. 2012;691:190-197. [PMID: 22796671 DOI: 10.1016/j.ejphar.2012.07.018]

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

A small erythropoietin derived non-hematopoietic peptide reduces cardiac inflammation, attenuates age associated declines in heart function and prolongs healthspan

Background

Aging is associated with increased levels of reactive oxygen species and inflammation that disrupt proteostasis and mitochondrial function and leads to organism-wide frailty later in life. ARA290 (cibinetide), an 11-aa non-hematopoietic peptide sequence within the cardioprotective domain of erythropoietin, mediates tissue protection by reducing inflammation and fibrosis. Age-associated cardiac inflammation is linked to structural and functional changes in the heart, including mitochondrial dysfunction, impaired proteostasis, hypertrophic cardiac remodeling, and contractile dysfunction. Can ARA290 ameliorate these age-associated cardiac changes and the severity of frailty in advanced age?

Methods

We conducted an integrated longitudinal (n = 48) and cross-sectional (n = 144) 15 months randomized controlled trial in which 18-month-old Fischer 344 x Brown Norway rats were randomly assigned to either receive chronic ARA290 treatment or saline. Serial echocardiography, tail blood pressure and body weight were evaluated repeatedly at 4-month intervals. A frailty index was calculated at the final timepoint (33 months of age). Tissues were harvested at 4-month intervals to define inflammatory markers and left ventricular tissue remodeling. Mitochondrial and myocardial cell health was assessed in isolated left ventricular myocytes. Kaplan-Meier survival curves were established. Mixed ANOVA tests and linear mixed regression analysis were employed to determine the effects of age, treatment, and age-treatment interactions.

Results

Chronic ARA290 treatment mitigated age-related increases in the cardiac non-myocyte to myocyte ratio, infiltrating leukocytes and monocytes, pro-inflammatory cytokines, total NF-κB, and p-NF-κB. Additionally, ARA290 treatment enhanced cardiomyocyte autophagy flux and reduced cellular accumulation of lipofuscin. The cardiomyocyte mitochondrial permeability transition pore response to oxidant stress was desensitized following chronic ARA290 treatment. Concurrently, ARA290 significantly blunted the age-associated elevation in blood pressure and preserved the LV ejection fraction. Finally, ARA290 preserved body weight and significantly reduced other markers of organism-wide frailty at the end of life.

Conclusion

Administration of ARA290 reduces cell and tissue inflammation, mitigates structural and functional changes within the cardiovascular system leading to amelioration of frailty and preserved healthspan.

The Effects of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) Oxidase and Erythropoietin, and Their Interactions in Angiogenesis: Implications in Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a leading cause of vision impairment and blindness in premature infants. Oxidative stress is implicated in its pathophysiology. NADPH oxidase (NOX), a major enzyme responsible for reactive oxygen species (ROS) generation in endothelial cells, has been studied for its involvement in physiologic and pathologic angiogenesis. Erythropoietin (EPO) has gained interest recently due to its tissue protective and angiogenic effects, and it has been shown to act as an antioxidant. In this review, we summarize studies performed over the last five years regarding the role of various NOXs in physiologic and pathologic angiogenesis. We also discuss the effect of EPO in tissue and vasoprotection, and the intersection of EPO and NOX-mediated oxidative stress in angiogenesis and the pathophysiology of ROP.

Extracellular matrix roles in cardiorenal fibrosis: Potential therapeutic targets for CVD and CKD in the elderly

Whereas hypertension, diabetes, and dyslipidemia are age-related risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD), aging alone is an independent risk factor. With advancing age, the heart and kidney gradually but significantly undergo inflammation and subsequent fibrosis, which eventually results in an irreversible decline in organ physiology. Through cardiorenal network interactions, cardiac dysfunction leads to and responds to renal injury, and both facilitate aging effects. Thus, a comprehensive strategy is needed to evaluate the cardiorenal aging network. Common hallmarks shared across systems include extracellular matrix (ECM) accumulation, along with upregulation of matrix metalloproteinases (MMPs) including MMP-9. The wide range of MMP-9 substrates, including ECM components and inflammatory cytokines, implicates MMP-9 in a variety of pathological and age-related processes. In particular, there is strong evidence that inflammatory cell-derived MMP-9 exacerbates cardiorenal aging. This review explores the potential therapeutic targets against CVD and CKD in the elderly, focusing on ECM and MMP roles.

The renal protect function of erythropoietin after release of bilateral ureteral obstruction in a rat model

Congenital urinary tract obstruction is one of the most frequent malformations in fetuses or neonates, which usually causes profound impairment of renal function including reductions in both glomerular filtration rate (GFR) and tubular handling of water and solutes. Although obstruction can be released by surgical operation, the child will suffer from diuresis for sometime. It has been reported that erythropoietin (EPO) could prevent the down-regulation of aquaporin-2 (AQP2) and urinary-concentrating defects induced by renal ischemia/reperfusion (I/R) injury. However, whether EPO could promote the recovery of renal function and AQP2 expression after releasing of ureteral obstruction has not been reported yet. The purposes of the present study were to investigate the effects of EPO on renal function and AQP2 expression after release of bilateral ureteral obstruction (BUO-R) in rats. The results showed that EPO could promote interleukin (IL) 10 (IL-10) expression; inhibit tumor necrosis factor-α (TNF-α), IL-6, and inducible nitric oxide synthase (iNOS) expressions; reduce the fractional excretion of sodium (FENa) and plasma creatinine (CREA) and urea; and promote the recovery of water and salt handling and AQP2 expression in BUO-R rats, especially in the high dose of EPO-treated group rats. In conclusion, EPO could promote the recovery of renal function and AQP2 expression in BUO-R rats, which may partially associate with its anti-inflammation effect.

Epoetin beta pegol ameliorates flow-mediated dilation with improving endothelial nitric oxide synthase coupling state in nonobese diabetic rats

Background/Aims

Patients with diabetic nephropathy have a high cardiovascular mortality. Epoetin beta pegol (continuous erythropoietin receptor activator, C.E.R.A.) is a drug for the treatment of renal anemia. In this study, we investigated the effect of C.E.R.A. on vascular endothelial function as evaluated by flow‐mediated dilation (FMD) and the relationship between hematopoiesis and FMD in diabetic nephropathy rats.

Methods

Male Spontaneously Diabetic Torii rats (SDT, 22 weeks old) were used. C.E.R.A. (0.6, 1.2 μg/kg) was administered subcutaneously once every 2 weeks for 8 weeks. At 1 week after last administration (31 weeks old), we assessed FMD in the femoral arteries of anesthetized rats using a high‐resolution ultrasound system. FMD was also measured 1 week after single C.E.R.A. treatment (5.0 μg/kg) to examine the influence of hematopoiesis.

Results

Flow‐mediated dilation was significantly decreased in SDT rats before the start of C.E.R.A. treatment (22 weeks old). Repeated administration of C.E.R.A. dose‐dependently improved FMD in SDT rats (31 weeks old) without changing blood glucose, nitroglycerin‐induced vasodilation, or kidney function. Long‐term administration of C.E.R.A. improved the state of endothelial nitric oxide synthase uncoupling in the femoral arteries of SDT rats, which showed a positive correlation with FMD. On the other hand, there was no correlation between FMD and Hb or Hct in SDT rats. Furthermore, at 1 week after single administration of C.E.R.A., FMD was not significantly improved although hemoglobin levels were comparable with levels following long‐term C.E.R.A. treatment.

Conclusion

Long‐term treatment with C.E.R.A. improved FMD in SDT rats even after onset of endothelial dysfunction.

Warming Up to New Possibilities with the Capsaicin Receptor TRPV1: mTOR, AMPK, and Erythropoietin

BACKGROUND

Transient receptor potential (TRP) channels are a superfamily of ion channels termed after the trp gene in Drosophila that are diverse in structure and control a wide range of biological functions including cell development and growth, thermal regulation, and vascular physiology. Of significant interest is the transient receptor potential cation channel subfamily V member 1 (TRPV1) receptor, also known as the capsaicin receptor and the vanilloid receptor 1, that is a non-selective cation channel sensitive to a host of external stimuli including capsaicin and camphor, venoms, acid/basic pH changes, and temperature.

METHODS

Given the multiple modalities that TRPV1 receptors impact in the body, we examined and discussed the role of these receptors in vasomotor control, metabolic disorders, cellular injury, oxidative stress, apoptosis, autophagy, and neurodegenerative disorders and their overlap with other signal transduction pathways that impact trophic factors.

RESULTS

Surprisingly, TRPV1 receptors do not rely entirely upon calcium signaling to affect cellular biology, but also have a close relationship with the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), and protein kinase B (Akt) that have roles in pain sensitivity, stem cell development, cellular survival, and cellular metabolism. These pathways with TRPV1 converge in the signaling of growth factors with recent work highlighting a relationship with erythropoietin (EPO). Angiogenesis and endothelial tube formation controlled by EPO requires, in part, the activation of TRPV1 receptors in conjunction with Akt and AMPK pathways.

CONCLUSION

TRPV1 receptors could prove to become vital to target disorders of vascular origin and neurodegeneration. Broader and currently unrealized implementations for both EPO and TRPV1 receptors can be envisioned for for the development of novel therapeutic strategies in multiple systems of the body.

Effect of recombinant erythropoietin on inflammatory markers in patients with affective disorders: A randomised controlled study

AIM

This study investigated the effect of repeated infusions of recombinant human erythropoietin (EPO) on markers of inflammation in patients with affective disorders and whether any changes in inflammatory markers were associated with improvements on verbal memory.

METHODS

In total, 83 patients were recruited: 40 currently depressed patients with treatment-resistant depression (TRD) (Hamilton Depression Rating Scale-17 items (HDRS-17) score >17) (sub-study 1) and 43 patients with bipolar disorder (BD) in partial remission (HDRS-17 and Young Mania Rating Scale (YMRS)⩽14) (sub-study 2). In both sub-studies, patients were randomised in a double-blind, parallel-group design to receive eight weekly intravenous infusions of EPO (Eprex; 40,000IU/ml) or saline (0.9% NaCl). Plasma concentrations of interleukin 6 (IL-6), interleukin 18 (IL-18) and high sensitive c-reactive protein (hsCRP) were measured at week 1 (baseline) and weeks 5, 9 and 14. HDRS-17 and neuropsychological function was assessed at weeks 1, 9 and 14 using a test battery including the RAVLT Auditory Verbal Learning Test (primary depression and primary cognition outcomes in the original trial).

RESULTS

EPO had no cumulative effect on plasma levels of IL-6 or IL-18 but increased hsCRP levels in patients with TRD (mean±SD change in ng/L: EPO: 0.43±1.64; Saline: -0.90±2.43; F(1,39)=4.78, p=0.04). EPO had no effects on inflammatory markers in BD. There was no correlation between change in inflammatory markers and change in verbal memory.

CONCLUSIONS

Repeated EPO infusions had no effect on IL-6 and IL-18 levels but produced a modest increase in hsCRP levels in patients with TRD. Changes over time in inflammatory markers were not correlated with changes in cognition suggesting that modulation of the inflammatory pathway is not a putative mechanism of the EPO-associated improvement of cognition in affective disorders.

Impaired renal endothelial nitric oxide synthase and reticulocyte production as modulators of hypertension induced by rHuEPO in the rat

Our aim was to study the effect of a broad range of recombinant human erythropoietin (rHuEPO) doses on hematological and biochemical parameters, blood pressure (BP), renal function and damage in the rat, focusing on endothelial nitric oxide synthase (eNOS) and hypoxia-inducible factors (HIFs). Male Wistar rats were divided in 5 groups receiving different doses of rHuEPO (100, 200, 400 and 600IU/kg body weight (BW)/week) and saline solution (control), during 3weeks. Blood and 24h urine were collected to perform hematological and biochemical analysis. BP was measured by the tail-cuff method. Kidney tissue was collected to mRNA and protein expression assays and to characterize renal lesions. A dose-dependent increase in red blood cells count, hematocrit and hemoglobin levels was found with rHuEPO therapy, in rHuEPO200, rHuEPO400 and rHuEPO600 groups. Increased reticulocyte count was found in rHuEPO400 and rHuEPO600 groups. BP raised in all groups receiving rHuEPO. The rHuEPO200 and rHuEPO600 groups presented increased kidney protein levels of HIF2α, a reduction in kidney protein levels of eNOS, and the highest grade of vascular and tubular renal lesions. Our study showed that rHuEPO-induced hypertension is present before significant hematological changes occur and, therefore, might involve direct (renal) and indirect (hematological) effects, which varies according to the dose used. The presence of renal hypoxia reduces eNOS activity. Excessive erythrocytosis increases blood hyperviscosity, which can be modulated by an increase in reticulocytes. Hypertension leads to early renal damage without alterations in traditional markers of renal function, thus underestimating the serious adverse effects and risks.

Direct vascular actions of quercetin in aorta from renal hypertensive rats

Background

Chronic treatment with the dietary flavonoid quercetin is known to lower blood pressure and restore endothelial dysfunction in animal models of hypertension. This study investigated the direct effects of quercetin on vascular response in chronic 2-kidney, 1-clip (2K1C) renal hypertensive rats. The effects of antioxidant vitamin ascorbic acid on the vasoreactivity were also examined.

Methods

2K1C renal hypertension was induced by clipping the left renal artery; age-matched rats that received sham treatment served as controls. Thoracic aortae were mounted in tissue baths for the measurement of isometric tension.

Results

Relaxant responses to acetylcholine were significantly attenuated in 2K1C rats in comparison with sham rats. Quercetin or ascorbic acid augmented acetylcholine-induced relaxation in 2K1C rats, whereas no significant differences were noted in sham rats. The relaxation response to sodium nitroprusside was comparable between 2K1C and sham rats, and sodium nitroprusside–induced relaxation was not altered by quercetin or ascorbic acid in either group. The contractile response to phenylephrine was significantly enhanced in 2K1C rats compared with sham rats. Phenylephrine-induced contraction was inhibited by pretreatment with quercetin or ascorbic acid in 2K1C rats, whereas neither chemical affected responses in sham rats. N^w-nitro-L-arginine methyl ester markedly augmented the contractile response to phenylephrine in sham rats, whereas no significant differences were observed in 2K1C rats. Quercetin or ascorbic acid did not affect phenylephrine-induced contraction in the presence of N^w-nitro-L-arginine methyl ester in either 2K1C or sham rats.

Conclusion

Acute exposure to quercetin appears to improve endothelium-dependent relaxation and inhibit the contractile response, similar to the effect of ascorbic acid in 2K1C hypertension. These results partially explain the vascular beneficial effects of quercetin in renal hypertension.

Regeneration in the nervous system with erythropoietin

Globally, greater than 30 million individuals are afflicted with disorders of the nervous system accompanied by tens of thousands of new cases annually with limited, if any, treatment options. Erythropoietin (EPO) offers an exciting and novel therapeutic strategy to address both acute and chronic neurodegenerative disorders. EPO governs a number of critical protective and regenerative mechanisms that can impact apoptotic and autophagic programmed cell death pathways through protein kinase B (Akt), sirtuins, mammalian forkhead transcription factors, and wingless signaling. Translation of the cytoprotective pathways of EPO into clinically effective treatments for some neurodegenerative disorders has been promising, but additional work is necessary. In particular, development of new treatments with erythropoiesis-stimulating agents such as EPO brings several important challenges that involve detrimental vascular outcomes and tumorigenesis. Future work that can effectively and safely harness the complexity of the signaling pathways of EPO will be vital for the fruitful treatment of disorders of the nervous system.

Erythropoietin and diabetes mellitus

Erythropoietin (EPO) is a 30.4 kDa growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus (DM). DM and the complications of this disease impact a significant portion of the global population leading to disability and death with currently limited therapeutic options. In addition to its utility for the treatment of anemia, EPO can improve cardiac function, reduce fatigue, and improve cognition in patients with DM as well as regulate cellular energy metabolism, obesity, tissue repair and regeneration, apoptosis, and autophagy in experimental models of DM. Yet, EPO can have adverse effects that involve the vasculature system and unchecked cellular proliferation. Critical to the cytoprotective capacity and the potential for a positive clinical outcome with EPO are the control of signal transduction pathways that include protein kinase B, the mechanistic target of rapamycin, Wnt signaling, mammalian forkhead transcription factors of the O class, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), and AMP activated protein kinase. Therapeutic strategies that can specifically target and control EPO and its signaling pathways hold great promise for the development of new and effective clinical treatments for DM and the complications of this disorder.

Epoetin beta pegol prevents endothelial dysfunction as evaluated by flow-mediated dilation in chronic kidney disease rats

Chronic kidney disease (CKD) patients have a poor prognosis due to cardiovascular disease. Anemia and endothelial dysfunction are important risk factors for cardiovascular events in CKD patients, and treatment with erythropoiesis-stimulating agent (ESA) has been reported to improve the quality of life in CKD patients. In this study, we evaluated the effect of anemia correcting dose of epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.) on endothelial function in 5/6 nephrectomized rats (Nx rats). C.E.R.A. was subcutaneously administered once a fortnight, 5 times in total, from 1 week after nephrectomy. Twenty-four hours after last administration, endothelial function was evaluated by measuring flow-mediated dilation (FMD) in the femoral arteries of anesthetized Nx rats by ultrasound system. Femoral arteries were harvested for western blot analysis. C.E.R.A. significantly increased FMD of Nx rats. Endothelium-independent vasodilation induced by nitroglycerin injection was not influenced by C.E.R.A treatment. Nox4 expression and nitrotyrosine accumulation were significantly decreased, and phosphorylation of eNOS was significantly enhanced in the femoral arteries of C.E.R.A.-treated rats. C.E.R.A. normalized hemoglobin levels but did not affect body weight, systolic blood pressure, heart rate, urinary protein excretion and plasma creatinine. These results indicate that C.E.R.A. prevented endothelial dysfunction in Nx rats, possibly through reduction of local oxidative stress and enhancement of eNOS phosphorylation in the arteries. This study provides the first evidence that C.E.R.A. prevented endothelial dysfunction in CKD model rats under conditions of amelioration of anemia.

Different Effects of 7-nitroindazole and L-NAME Administered Both Individually and Together on the Cardiovascular System of the Rat

We evaluated the effects of NG-nitro-L-arginine methylester (L-NAME) (50 mg/kg/day) and 7-nitroindazole (7NI) (10 mg/kg/day) administered from 10th-16th week of age either individually or together on cardiovascular system of Wistar rats and SHR. Systolic blood pressure (sBP) was measured weekly by the plethysmographic method. For morphological studies, the animals (n=10) were perfused with a fixative (120 mm Hg), and thoracic aorta and carotid and coronary arteries were processed for electron microscopy. For functional investigation (n=10), aortic rings were used in an organ bath. In Wistar rats, L-NAME evoked an increase of sBP; hypertrophy of the heart and arterial walls; an increase in cross-sectional areas (CSA) of endothelial cells (EC), muscle cells (SMC), extracellular matrix (ECM), and a decrease in acetylcholine-induced endothelial-dependent relaxation (EDR). 7NI evoked sBP-independent hypotrophy of the heart and arterial walls, a decrease in CSA of EC and SMC without affecting the CSA of ECM, and a mild decrease in acetylcholine-induced EDR. 7NI and L-NAME administered together evoked lower effect on BP and trophicity of the heart and all arteries, and a similar decrease in acetylcholine-induced EDR compared to L-NAME alone. In SHR, 7NI did not evoke any effect on the studied parameters.

Erythropoietin prevents endothelial dysfunction in GTP-cyclohydrolase I-deficient hph1 mice

: In this study, we used the mutant hph1 mouse model, which has deficiency in GTP-cyclohydrolase I (GTPCH I) activity, to test the hypothesis that erythropoietin (EPO) protects aortic wall from oxidative stress induced by uncoupling of endothelial nitric oxide synthase (eNOS). Both GTPCH I activity and tetrahydrobiopterin (BH4) levels were reduced in hph1 mice, whereas 7,8-dihydrobiopterin (7,8-BH2) levels were significantly increased. Furthermore, BH4 deficiency caused increased production of superoxide anion and hydrogen peroxide in the aorta thus resulting in impairment of endothelium-dependent relaxations to acetylcholine. Treatment of hph1 mice with recombinant human EPO (1000 U/kg, subcutaneously for 3 days) significantly decreased superoxide anion production by eNOS and improved BH4 to 7,8-BH2 ratio in aortas. EPO also significantly decreased production of hydrogen peroxide and improved endothelium-dependent relaxations in aortas of hph1 mice. In addition, EPO treatment increased protein expressions of copper-/zinc-superoxide dismutase, manganese-superoxide dismutase, and catalase in the aorta of hph1 mice. Our findings demonstrate that treatment with EPO prevented oxidative stress and endothelial dysfunction caused by eNOS uncoupling. Increased vascular expressions of antioxidants seem to be an important molecular mechanism underlying vascular protection by EPO during chronic BH4 deficiency.

Associations among epoetin therapy, inflammation, nutritional status, and mortality in patients on hemodialysis

OBJECTIVE

Inflammation contributes to hemopoiesis by lowering responses to epoetin (EPO) and to an increase in the mortality of patients on hemodialysis. However, nutritional status might alter associations among inflammation, EPO responsiveness, and the risk of mortality. We assessed the effect of inflammation on mortality according to nutritional status among EPO responses in a cohort of prevalent hemodialysis patients.

DESIGN AND METHODS

The observational cohort study analyzed data from the Japanese Dialysis Registry (2005-2006; n = 36,956; mean follow-up 11.5 months). Patients were categorized into tertiles of the EPO responsiveness index (ERI; the weekly weight-adjusted EPO dose [IU/kg/week] divided by hemoglobin [g/dL]) and an EPO-free group. Body mass index (BMI) and C-reactive protein (CRP) levels were measured.

RESULTS

Bimodal peaks indicated associations between CRP and BMI in each group. Hazard ratio (HR) curves of CRP for mortality according to BMI in the upper ERI tertile, particularly among those with diabetes mellitus (DM), were reverse J-shaped. However, HR curves in the other groups were increased below a threshold BMI of 21 kg/m(2). These associations were confirmed in propensity score-matched populations.

CONCLUSION

Risk of CRP for death is apparently changed by BMI in hemodialysis patients with a lower EPO response, especially in those with DM.

Pyruvate minimizes rtPA toxicity from in vitro oxygen-glucose deprivation and reoxygenation

Clinical application of recombinant tissue plasminogen activator (rtPA) for stroke is limited by hemorrhagic transformation, which narrows rtPA's therapeutic window. In addition, mounting evidence indicates that rtPA is potentially neurotoxic if it traverses a compromised blood brain barrier. Here, we demonstrated that pyruvate protects cultured HT22 neuronal and primary microvascular endothelial cells co-cultured with primary astrocytes from oxygen glucose deprivation (OGD)/reoxygenation stress and rtPA cytotoxicity. After 3 or 6h OGD, cells were reoxygenated with 11mmol/L glucose±pyruvate (8mmol/L) and/or rtPA (10µg/ml). Measured variables included cellular viability (calcein AM and annexin-V/propidium iodide), reactive oxygen species (ROS; mitosox red and 2',7'-dichlorofluorescein diacetate), NADPH, NADP(+) and ATP contents (spectrophotometry), matrix metalloproteinase-2 (MMP2) activities (gelatin zymography), and cellular contents of MMP2, tissue inhibitor of metalloproteinase-2 (TIMP2), and phosphor-activation of anti-apoptotic p70s6 kinase, Akt and Erk (immunoblot). Pyruvate prevented the loss of HT22 cells after 3h OGD±rtPA. After 6h OGD, rtPA sharply lowered cell viability; pyruvate dampened this effect. Three hours OGD and 4h reoxygenation with rtPA increased ROS formation by about 50%. Pyruvate prevented this ROS formation and doubled cellular NADPH/NADP(+) ratio and ATP content. In endothelial cell monolayers, 3h OGD and 24h reoxygenation increased FITC-dextran leakage, indicating disruption of intercellular junctions. Although rtPA exacerbated this effect, pyruvate prevented it while sharply lowering MMP2/TIMP2 ratio and increasing phosphorylation of p70s6 kinase, Akt and Erk. Pyruvate protects neuronal cells and microvascular endothelium from hypoxia-reoxygenation and cytotoxic action of rtPA while reducing ROS and activating anti-apoptotic signaling. These results support the proposed use of pyruvate as an adjuvant to dampen the side effects of rtPA treatment, thereby extending rtPA's therapeutic window.

A specific immune transcriptomic profile discriminates chronic kidney disease patients in predialysis from hemodialyzed patients

BACKGROUND

Chronic kidney disease (CKD) patients present a complex interaction between the innate and adaptive immune systems, in which immune activation (hypercytokinemia and acute-phase response) and immune suppression (impairment of response to infections and poor development of adaptive immunity) coexist. In this setting, circulating uremic toxins and microinflammation play a critical role. This condition, already present in the last stages of renal damage, seems to be enhanced by the contact of blood with bioincompatible extracorporeal hemodialysis (HD) devices. However, although largely described, the cellular machinery associated to the CKD- and HD-related immune-dysfunction is still poorly defined. Understanding the mechanisms behind this important complication may generate a perspective for improving patients outcome.

METHODS

To better recognize the biological bases of the CKD-related immune dysfunction and to identify differences between CKD patients in conservative (CKD) from those in HD treatment, we used an high-throughput strategy (microarray) combined with classical bio-molecular approaches.

RESULTS

Immune transcriptomic screening of peripheral blood mononuclear cells (1030 gene probe sets selected by Gene-Ontology) showed that 275 gene probe sets (corresponding to 213 genes) discriminated 9 CKD patients stage III-IV (mean±SD of eGFR: 32.27+/-14.7 ml/min) from 17 HD patients (p<0.0001, FDR=5%). Seventy-one genes were up- and 142 down-regulated in HD patients. Functional analysis revealed, then, close biological links among the selected genes with a pivotal role of PTX3, IL-15 (up-regulated in HD) and HLA-G (down-regulated in HD). ELISA, performed on an independent testing-group [11 CKD stage III-IV (mean±SD of eGFR: 30.26±14.89 ml/min) and 13 HD] confirmed that HLA-G, a protein with inhibition effects on several immunological cell lines including natural killers (NK), was down-expressed in HD (p=0.04). Additionally, in the testing-group, protein levels of CX3CR1, an highly selective chemokine receptor and surface marker for cytotoxic effector lymphocytes, resulted higher expressed in HD compared to CKD (p<0.01).

CONCLUSION

Taken together our results show, for the first time, that HD patients present a different immune-pattern compared to the un-dialyzed CKD patients. Among the selected genes, some of them encode for important biological elements involved in proliferation/activation of cytotoxic effector lymphocytes and in the immune-inflammatory cellular machinery. Additionally, this study reveals new potential diagnostic bio-markers and therapeutic targets.

Oxidant stress and signal transduction in the nervous system with the PI 3-K, Akt, and mTOR cascade

Oxidative stress impacts multiple systems of the body and can lead to some of the most devastating consequences in the nervous system especially during aging. Both acute and chronic neurodegenerative disorders such as diabetes mellitus, cerebral ischemia, trauma, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and tuberous sclerosis through programmed cell death pathways of apoptosis and autophagy can be the result of oxidant stress. Novel therapeutic avenues that focus upon the phosphoinositide 3-kinase (PI 3-K), Akt (protein kinase B), and the mammalian target of rapamycin (mTOR) cascade and related pathways offer exciting prospects to address the onset and potential reversal of neurodegenerative disorders. Effective clinical translation of these pathways into robust therapeutic strategies requires intimate knowledge of the complexity of these pathways and the ability of this cascade to influence biological outcome that can vary among disorders of the nervous system.