MO953: Relevance of Proteinuria and Donor Specific Antibody in Kidney Transplanted Recipients and Allograft Outcomes

BACKGROUND AND AIMS

The onset of proteinuria in renal allograft recipients is a frequent complication that may be associated with an increased risk of graft failure and mortality. Our aim was to research if proteinuria effects is independent from donor specific antibody (DSA) for transplant graft survival and the changes of proteinuria response to therapy in ABMR group.

METHOD

85 transplanted patients were enrolled in our study and followed up till 31 October 2020 or till death, or date of return to dialysis. We created three groups: ABMR group (n = 19, biopsy proven antibody mediated rejection), ABMRDSApos positive group (n = 14) ABMRDSAneg (n = 5), DSA negative group with stabile kidney function without rejection as a reference (n = 52). Differences in patient, donor and transplant characteristics between DSA positive and negative groups were assessed by Fishers exact test for categorical variables. Death censored graft loss was assessed by Kaplan Meier analysis with log risk statistics.

RESULTS

Proteinuria decrease after treatment in ABMR group (P = 0.0009). Graft failure's frequency increase every 10 mg/mmol elevation of proteinuria means 7% elevation (hazard ratio: 1.07%). Before treatment nephrotic proteinuria was found in group AMBRDSApoz 21%, 14,29% in group ABMR DSAneg 1,92% in reference group. Estimated 3-year graft survival was 87, 5% in ABMR group, 93% in DSA pos group, and 100% in DSA negative group (log-rank probe P = 0.0666).

CONCLUSION

The presence of DSA increases graft loss but it is independent to proteinuria. Therapy refractory proteinuria state represents worse graft survival.

Cardioprotective Role of BGP-15 in Ageing Zucker Diabetic Fatty Rat (ZDF) Model: Extended Mitochondrial Longevity

Impaired mitochondrial function is associated with several metabolic diseases and health conditions, including insulin resistance and type 2 diabetes (T2DM), as well as ageing. The close relationship between the above-mentioned diseases and cardiovascular disease (CVD) (diabetic cardiomyopathy and age-related cardiovascular diseases) has long been known. Mitochondria have a crucial role: they are a primary source of energy produced in the form of ATP via fatty acid oxidation, tricarboxylic acid (TCA) cycle, and electron transport chain (ETC), and ATP synthase acts as a key regulator of cardiomyocyte survival. Mitochondrial medicine has been increasingly discussed as a promising therapeutic approach in the treatment of CVD. It is well known that vitamin B3 as an NAD+ precursor exists in several forms, e.g., nicotinic acid (niacin) and nicotinamide (NAM). These cofactors are central to cellular homeostasis, mitochondrial respiration, ATP production, and reactive oxygen species generation and inhibition. Increasing evidence suggests that the nicotinic acid derivative BGP-15 ((3-piperidine-2-hydroxy-1-propyl)-nicotinic amidoxime) improves cardiac function by reducing the incidence of arrhythmias and improves diastolic function in different animal models. Our team has valid reasons to assume that these cardioprotective effects of BGP-15 are based on its NAD+ precursor property. Our hypothesis was supported by an animal experiment where ageing ZDF rats were treated with BGP-15 for one year. Haemodynamic variables were measured with echocardiography to detect diabetic cardiomyopathy (DbCM) and age-related CVD as well. In the ZDF group, advanced HF was diagnosed, whereas the BGP-15-treated ZDF group showed diastolic dysfunction only. The significant difference between the two groups was supported by post-mortem Haematoxylin and eosin (HE) and Masson’s trichrome staining of cardiac tissues. Moreover, our hypothesis was further confirmed by the significantly elevated Cytochrome c oxidase (MTCO) and ATP synthase activity and expression detected with ELISA and Western blot analysis. To the best of our knowledge, this is the first study to demonstrate the protective effect of BGP-15 on cardiac mitochondrial respiration in an ageing ZDF model.

P0508NEPHROTIC SYNDROME DUE TO HEAVY AND LIGHT CHAIN (AHL) AMYLOIDOSIS

Background and Aims

Kidney diseases with heavy chain deposition are rare, including AHL amyloidosis also. The mutation/deletion of the constant domain (CH1/CH2) of the heavy chain causing high tissue affinity seems most likely in its pathogenesis. The very low serum level is responsible for the difficult diagnosis, which is often based on kidney biopsy or laser microdissection / mass spectrometry.

Method

Case study of a 76-year-old male patient, examined in January, 2019.

Results

Besides treatment for Ménière syndrome and benign prostatic hyperplasia there was no other important event in patient’s history. Significant proteinuria and microscopic haematuria were observed from May 2016, but eGFR was 70 ml/min/1,73 m2 at that time. By April, 2018 nephrotic range proteinuria (10 g/day) with full nephrotic syndrome developed. Screening tests for cancer were negative. Despite symptomatic treatment, half year later eGFR decreased to 27 ml/min/1,73 m2, therefore he was referred to nephrology. Serum protein electrophoresis verified IgG lambda (8,1 g/l) and free lambda (0,5 g/l) monoclonal light chains, and in addition the possibility of IgG heavy chain accumulation. Urine electrophoresis showed also IgG lambda (1720,1 mg/l), and free lambda light chain (552,1 mg/l) monoclonality. Serum free lambda and kappa light chain ratio was 0,06, complement serology was normal. Kidney biopsy was done, which showed IgG heavy and light chain restriction, Congo red stain positivity and apple green birefringence under the polarized microscope in the expanded mesangium, in the interstitium and along the tubular basement membrane and the blood vessels. The electron microscope detected fibrillary deposits (10 nm) in the same structures, therefore diagnosis of AHL amyloidosis was established. He had no extrarenal symptoms. Bone marrow aspiration flow cytometry verified 1,11% plasma cell accumulation, 93% of them had pathological immunphenotype. Bone marrow morphology assay showed 30-40% plasma cell infiltration, and chromosome assay detected monoallelic deletion of IgH and MAF and gains of 1q region, suggesting myeloma multiplex in the background of AHL amyloidosis. VCD (bortezomib-cyclophosphamide-dexamethason) treatment was started, so far he has received 8 cycles. He is asymptomatic, proteinuria decreased, kidney function stabilized, eGFR 23 ml/min/1,73 m2.

Conclusion

only about 20 cases of AHL amyloidosis have been reported in the literature so far. In the context of longstanding kidney failure with nephrotic syndrome, we should consider renal disease associated with plasma cell dyscrasia also. If case of an AHL amyloidosis caused by myeloma multiplex, effective anti-plasma cell therapy can improve the hematological and the renal outcome.

P0212IMMUNOSUPPRESSIVE TREATMENT OF PATIENTS WITH ANCA ASSOCIATED VASCULITIS (AAV) IN CHRONIC DIALYSIS PROGRAM

Background and Aims

There are numerous studies on AAV, however, data describing the use of immunosuppressive treatment in AAV patients (pts) on chronic dialysis are limited. Most studies found that the incidence of infection is much higher than that of relapses (0.05-0.1 pt per year), suggesting that immunosuppression should be stopped after 3 months in pts with end-stage renal failure.

Material, Method

Retrospective analysis of immunosuppressive treatment in pts on chronic dialysis due to AAV. From 1995 to 2019 139 pts were diagnosed with AAV. Among them 38 patients (26 female, 12 male, mean age 58 years) needed chronic dialysis (>90 days) due to severe renal AAV (29), relapsing renal disease (6) or progressive CKD without active vasculitis (3).

Results

Microscopic polyangiitis was diagnosed in 20, granulomatosis with polyangiitis in 14, eosinophilic granulomatosis with polyangiitis in 4 cases. MPO-ANCA was more frequent than PR3-ANCA (23 vs 12), in one case both ANCAs were positive, and in two cases both were negative. The mean dialysis duration was 55 months (4–180 months). 18 pts (47%) had at least one relapse during the observation period. The mean age, the clinical diagnosis, the type of ANCA did not cause any difference, the dialysis time was longer in the relapsed pts group (72+/-38 vs. 40+/-29 months) compared to pts without relapse. High relapse rate was seen in 6 cases. Three patient had continuously high level of PR3-ANCA without relapse or any sign of disease. Relapses were treated mostly with combined therapy of corticosteroids and oral/intravenous cyclophosphamide followed by azathioprin maintenance therapy. Cortocosteroid alone was used in 7 pts, rituximab in five pts as maintenance therapy. Serious infection (needing hospital care) rate during any immunosuppressive treatment was 0.12 per patient-years. There were 12 deaths on dialysis, the median time to death was 61 months (range 3–132). The deaths rate was higher (9/18 vs. 4/20) in relapsed pts, 4 occurring during immunosuppressive treatment. Causes of deaths were cardiovascular (8), sepsis (3), malignancy (2 pts). Seven pts received kidney grafts, 15 pts remained on dialysis, but in three case dialysis could be discontinued after 16, 35 and 36 months.

Conclusion

Our study points to higher relapse rate and lower serious infection rate in AAV pts on chronic dialysis compared to previous studies. It seems reasonable to continue immunosuppression above 3 months in pts remaining on chronic dialysis. This approach may decrease the relapse rate preventing damage of other organs, allowing transplantation and in some pts recovery of renal function could be achieved.

Ferritin Light Chain Confers Protection Against Sepsis-Induced Inflammation and Organ Injury

Despite the prevalence and recognition of its detrimental impact, clinical complications of sepsis remain a major challenge. Here, we investigated the effects of myeloid ferritin heavy chain (FtH) in regulating the pathogenic sequelae of sepsis. We demonstrate that deletion of myeloid FtH leads to protection against lipopolysaccharide-induced endotoxemia and cecal ligation and puncture (CLP)-induced model of sepsis as evidenced by reduced cytokine levels, multi-organ dysfunction and mortality. We identified that such protection is predominantly mediated by the compensatory increase in circulating ferritin (ferritin light chain; FtL) in the absence of myeloid FtH. Our in vitro and in vivo studies indicate that prior exposure to ferritin light chain restrains an otherwise dysregulated response to infection. These findings are mediated by an inhibitory action of FtL on NF-κB activation, a key signaling pathway that is implicated in the pathogenesis of sepsis. We further identified that LPS mediated activation of MAPK pathways, specifically, JNK, and ERK were also reduced with FtL pre-treatment. Taken together, our findings elucidate a crucial immunomodulatory function for circulating ferritin that challenges the traditional view of this protein as a mere marker of body iron stores. Accordingly, these findings will stimulate investigations to the adaptive nature of this protein in diverse clinical settings.

Upregulation of Myocardial and Vascular Phosphodiesterase 9A in A Model of Atherosclerotic Cardiovascular Disease

Atherosclerosis is strongly associated with cardiac dysfunction and heart failure. Besides microvascular dysfunction and diminishment of the cardiac nitric oxide-Protein Kinase G (NO-PKG) pathway, recent evidence suggests that phosphodiesterase 9A (PDE9A) enzyme has an unfavorable role in pathological changes. Here, we characterized a rabbit model that shows cardiac dysfunction as a result of an atherogenic diet, and examined the myocardial PDE9A signaling. Rabbits were divided into Control (normal diet) and HC (atherogenic diet) groups. Cardiac function was evaluated by echocardiography. Vascular function was assessed, along with serum biomarkers. Histological stains were conducted, expression of selected proteins and cyclic guanosine monophosphate (cGMP) levels were determined. Signs of diastolic dysfunction were shown in HC animals, along with concentric hypertrophy and interstitial fibrosis. Endothelial function was diminished in HC rabbits, along with marked reduction in the aortic lumen, and increased left ventricle outflow tract (LVOT) pressures. A significant increase was shown in myocardial PDE9A levels in HC animals with unchanged vasodilator-stimulated phosphoprotein (VASP) phosphorylation and cGMP levels. Upregulation of PDE9A may be associated with early stage of cardiac dysfunction in atherosclerotic conditions. Since PDE9A is involved in cGMP degradation and in deactivation of the cardioprotective PKG signaling pathway, it may become an encouraging target for future investigations in atherosclerotic diseases.

Herpes Simplex Virus Decreases Endothelial Cell Plasminogen Activator Inhibitor

Herpes simplex virus (HSV) infection is histopathologically associated with vascular injury, fibrinoid necrosis and inflammatory cell infiltrates. We have previously shown in vitro that HSV infection of human umbilical vein endothelial cells (HUVEC) promotes a procoagulant phenotype manifest by the induction of tissue factor, the loss of thrombomodulin, and an increase in platelet adhesion. In these studies we examined the effects of HSV infection on HUVEC plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (t-PA). HSV infection caused the loss of PAI-1 in the extracellular matrix (ECM) and that released into the supernatant of HUVEC. Both activity and antigen levels of the Serpin inhibitor are diminished as a result of HSV infection. The loss of inhibitor is not secondary to diminished vitronectin (Vn), the primary binding protein of PAI-1 in the ECM, but appears to be secondary to decreased synthesis at the RNA level. Tissue plasminogen activator (t-PA). synthesis is also decreased in endothelial HSV infection. PAI-1 loss may further promote a procoagulant phenotype in HSV infection in vivo.

The Effects of Long-Term, Low- and High-Dose Beta-Carotene Treatment in Zucker Diabetic Fatty Rats: The Role of HO-1

Nowadays, there is a growing interest in compounds derived from plants as potential raw materials for drug development. One of the most studied compounds is beta-carotene (BC). Several clinical studies can be found investigating the cardiovascular effects of BC, however, all these results are controversial. There is an increasing body of evidence showing that besides the well-known antioxidant properties, under strong oxidative circumstances, BC could become prooxidant as well. In this study, we investigated the effects of long-term, low- and high-dose BC treatment in ischemic/reperfused (ISA/REP) hearts isolated from Zucker diabetic fatty (ZDF) rats. The animals were treated with various daily doses of BC for 4 weeks and then hearts were isolated and subjected to 30 min of global ischemia (ISA) followed by 120 min of reperfusion (REP). Blood glucose levels were measured before, after two weeks, and at the end of the treatment. In isolated hearts, the myocardial function was registered. At the end of the reperfusion period, the infarct size (IS) and heme oxygenase-1 (HO-1) expression were measured. The results showed that a low dose of BC treatment significantly improved postischemic recovery, which was reflected in a decreased IS. Interestingly, when BC was applied at high concentrations, the observed protective effects were lost. Although BC treatment increased HO-1 expression, we did not observe a better heart function and/or decreased IS in the high-dose-treated group. Glucose tolerance tests showed a concentration-independent decrease in blood glucose levels. Our results suggest that long-term, low-dose BC treatment could be effective in the treatment of type-2-diabetes and related cardiovascular diseases.

Microthrombotic renal involvement in an SLE patient with concomitant catastrophic antiphospholipid syndrome: the beneficial effect of rituximab treatment

Antiphospholipid syndrome is characterized by multiple arterial and/or venous thrombotic events, recurrent fetal losses in the presence of antiphospholipid antibodies (aPL). Catastrophic antiphospholipid syndrome is a life-threatening, rare subset of antiphospholipid syndrome when the thrombotic events affect at least three organs, and clinical manifestations develop simultaneously or within a week. Diagnostically, small vessel occlusions can be detected by histopathology in the presence of aPL. Our case report describes an 18-year-old man who has been treated for antiphospholipid syndrome associated with systemic lupus erythematosus (SLE) since 2011. The clinical findings were dominated by recurrent deep vein thrombosis, and severe proteinuria caused by lupus nephritis, accompanied by mild serological and laboratory findings. The patient was hospitalized in March 2014 because of severe thrombocytopenia and infective diarrhoea. At this time the renal functions deteriorated rapidly. Simultaneously, left upper extremity paresis was observed; computed tomography showed ischaemic lesions in the territory of the middle cerebral artery. Abdominal discomfort and pain occurred. On computed tomography scan ischaemic lesions were seen in the spleen, the right kidney and the coeliac trunk. Laboratory and serological findings verified the presence of aPL and anti-DNA antibodies, anaemia and thrombocytopenia. Based on the above-mentioned clinical and laboratory findings, the diagnosis of catastrophic antiphospholipid syndrome was established. Anticoagulation, corticosteroids and plasma exchange treatment, as well as haemodiafiltration were initiated. Although the thrombotic cascade decelerated following these interventions, we could not see an improvement in the renal function. Rituximab treatment was started, leading to a significant improvement in renal function. After 5 weeks of treatment the patient was discharged from hospital.

Murine model to follow hyphal development in invasive pulmonary aspergillosis

Aspergillus fumigatus is an opportunistic pathogen, the leading cause of invasive and disseminated aspergillosis in systemic immunocompromised patients, and an important cause of mortality. The aim of the present study was to adapt a pulmonary aspergillosis murine model, to determine pathodynamical parameters quantitatively, and to follow the progression of fungal infection in vivo. The nasal inoculation of Aspergillus conidia in mice previously subjected to immunosuppression with cyclophosphamide (CP) turned out to be a more suitable model than that of immunosuppressed with hydrocortisone (HC). The following parameters were found to correlate quantitatively with the progress of the infection: (i) survival rate, (ii) weight loss of mice, (iii) infected focal plaque size, (iv) hyphal density, (v) hyphal length distribution of A. fumigatus, and the (vi) the histopathological status and scores. These parameters will be essential elements for the development of antifungal drugs and therapies, and important for the investigation of the pathogenicity in different strains of A. fumigatus.

The Accuracy of Tissue Resonance Interaction Method Probe (Trimprob Tm) in Non-Invasive Diagnosis of Prostatic Cancer. Analysis of the Results of 782 Patients

The aim of our study was to evaluate the real utility of the TRIMprob test before TRUS-guided biopsy approach, putting in relation the number of positive tests of the TRIMprob with the number of positive prostate biopsies that were performed successfully. Sensitivity, Specificity, PPV (Positive predicted value), NPV (Negative predicted value) of the TRIMprob test were analyzed with statistical software package for Social Sciences (SPSS Inc, Chicago, Illinois USA).

Heme Oxygenase-1: Clinical Relevance in Ischemic Stroke

Stroke is the second-leading cause of death and a leading cause of serious long-term disability worldwide, with an increasing global burden due to the growing and aging population. However, strict eligibility criteria for current treatment opportunities make novel therapeutic approaches desirable. Oxidative stress plays a pivotal role during cerebral ischemia, eventually leading to neuronal injury and cell death. The significant correlation between redox imbalance and ischemic stroke has led to various treatment strategies targeting the endogenous antioxidant system in order to ameliorate the adverse prognosis in patients with cerebral infarction. One of the most extensively investigated cellular defense pathway in this regard is the Nrf2-heme oxygenase-1 (HO-1) axis. In this review, our aim is to focus on the potential clinical relevance of targeting the HO-1 pathway in ischemic stroke.

Cardiovascular Screening and Management Among Kidney Transplant Candidates in Hungary

INTRODUCTION

Cardiovascular disease is a major cause of morbidity and mortality in end-stage renal disease patients on dialysis and the most common cause of death in the immediate post-transplantation period. The aim of our study was to describe a novel approach of cardiovascular screening and management of dialysis patients evaluated for the transplant waiting list.

METHODS

Twenty-eight patients with end-stage renal disease put on the waiting list between July 2013 and July 2014 were subjected to a prespecified cardiovascular screening protocol utilizing noninvasive and/or invasive tests. Patients were subsequently divided into 3 strata in terms of their estimated cardiovascular risk. Each of these groups were then prescribed interventions aiming to improve their cardiovascular condition.

RESULTS

According to our prespecified protocol of cardiovascular screening studies, 15 (54%) patients were identified as low, 5 (18%) as intermediate, and 8 (28%) as high risk. Four (14%) patients were current smokers. In the low-risk group, we initiated a patient education program involving counseling on regular exercise such as swimming or cycling to improve their functional capacity. In the high-risk group revascularization was done in 5 cases (63%), including 3 percutaneous transluminal coronary angioplasties (PTCA) with stents for single-vessel disease, and coronary artery bypass graft surgeries (CABG) for triple-vessel disease in 2 cases. In the medium-risk group medical management was opted for, including introduction of beta-blockers, inhibitors, statins, and ezetimibe, as well as efforts to optimize anemia management, indices of bone-mineral disease, and fluid status.

CONCLUSION

In our regional transplant program, we introduced a comprehensive multidisciplinary approach to treat potential transplant candidates according to cardiovascular risk stratification based on a prespecified screening protocol. Further studies are needed to correlate this novel strategy with post-transplantation outcomes.

Macrophage and epithelial cell H-ferritin expression regulates renal inflammation

Inflammation culminating in fibrosis contributes to progressive kidney disease. Crosstalk between the tubular epithelium and interstitial cells regulates inflammation by a coordinated release of cytokines and chemokines. Here we studied the role of heme oxygenase-1 (HO-1) and the heavy subunit of ferritin (FtH) in macrophage polarization and renal inflammation. Deficiency in HO-1 was associated with increased FtH expression, accumulation of macrophages with a dysregulated polarization profile, and increased fibrosis following unilateral ureteral obstruction in mice; a model of renal inflammation and fibrosis. Macrophage polarization in vitro was predominantly dependent on FtH expression in isolated bone marrow-derived mouse monocytes. Utilizing transgenic mice with conditional deletion of FtH in the proximal tubules (FtHPT−/−) or myeloid cells (FtHLysM−/−), we found that myeloid FtH deficiency did not affect polarization or accumulation of macrophages in the injured kidney compared to wild-type (FtH+/+) controls. However, tubular FtH deletion led to a marked increase in pro-inflammatory macrophages. Furthermore, injured kidneys from FtHPT−/− mice expressed significantly higher levels of inflammatory chemokines and fibrosis compared to kidneys from FtH+/+ and FtHLysM−/− mice. Thus, there are differential effects of FtH in macrophages and epithelial cells, which underscores the critical role of FtH in tubular-macrophage crosstalk during kidney injury.

Cardioprotective effects of sour cherry seed extract (SCSE) on the hypercholesterolemic rabbit heart

HYPOTHESIS

The present study evaluates the hypothesis that sour cherry seed extract (SCSE) protects against cardiovascular disease and inflammation in hypercholesterolemic rabbits, and that this protection correlates with SCSE-induced activity of heme oxygenase- 1 (HO-1), a cytoprotective enzyme contributing to oxidative stress responses.

METHODS

18 New Zealand white rabbits were divided into three groups receiving: I. cholesterol-free rabbit chow; II. chow containing 2% cholesterol; or III. 2% cholesterol plus SCSE for 16 weeks. Heart functions were monitored by echocardiography 0, 4, and 16 weeks after the initiation of cholesterol-supplemented feeding. At the 16-week time-point, isolated hearts were subjected to ischemia-reperfusion (I/R), followed by measurement of heart rate (HR), aortic flow (AF), coronary flow (CF), aortic pressure (AoP), and left ventricular developed pressure (LVDP). Myocardial infarct size was determined using triphenyl tetrazolium chloride (TTC). Quantification of fatty streaks was assessed using Sudan-III staining. Western blot analysis was used to determine the content of cytochrome c oxidase III (COX III), vascular endothelial growth factor (VEGF), and HO-1 in the myocardium.

RESULTS

Relative to cholesterol-treated animals not receiving SCSE, SCSE-treated animals exhibited significantly improved cardiac function and improved peak early diastolic velocity to peak atrial velocity ratio (E'/A'), along with decreased atherosclerotic plaque formation and infarct size. Increased HO-1 and COX III protein expression and COX activity were also noted in hearts from SCSE-treated rabbits.

CONCLUSIONS

This study demonstrates SCSE cardioprotective effects on hypercholesterolemic hearts. Correlation of these outcomes with HO-1 expression suggests that the effect may be mediated by activity of this enzyme. However, definitive proof of HO-1 dependence requires further investigation.

The cellular autophagy markers Beclin-1 and LC3B-II are increased during reperfusion in fibrillated mouse hearts

Autophagy is an intracellular bulk degradation process for elimination of damaged macromolecules and organelles. In the past decades, the scientific community has gained increasingly detailed understanding of the role of autophagy in myocardial homeostasis, although still many controversies remain. In the ischemic myocardium, autophagy appears to be beneficial for survival, whereas upon reperfusion the process may induce cell death. However, the overall effect of autophagy seems to depend on the duration and intensity of stress, as along with the extent of autophagy within myocardial tissue. Reperfusion of an ischemic heart maybe harmful, but it is an essential process for myocardial survival. One of the major adverse consequences of reperfusion is the occurrence of ventricular fibrillation (VF). In the present study, we investigated the possible connection between autophagy and VF. Isolated mouse hearts were subjected to ischemia/reperfusion (I/R) and divided into two groups based on the development of VF at the beginning of reperfusion. Western blot analysis was conducted for autophagy-associated proteins LC3B, ATG-5, ATG-7, ATG-12, Bcl-2 and Beclin-1 proteins. Significantly higher level of Beclin-1 and LC3B-II/LC3B-I ratio (both definitive autophagy biomarkers) was observed in the fibrillated myocardium, versus tissue from the nonfibrillated hearts. Interestingly, although Bcl-2 is a major regulator of Beclin-1, level of this protein was not significantly altered in tissue from fibrillated, versus non-fibrillated hearts. Moreover, Atg7 expression showed a trend, albeit nonsignificant, towards elevation in fibrillated versus non-fibrillated hearts. Results of the present investigation demonstrate a possible link between VF and autophagy. Studies by authors of this report to evaluate potential etiologic relationships between the two processes are ongoing.

Adverse impact of diet-induced hypercholesterolemia on cardiovascular tissue homeostasis in a rabbit model: time-dependent changes in cardiac parameters

The present study evaluates a hypothesis that diet-related hypercholesterolemia increases oxidative stress-related burden to cardiovascular tissue, resulting in progressively increased mortality, along with deterioration of electrophysiological and enzymatic function in rabbit myocardium. New Zealand white rabbits were divided into four groups, defined as follows: GROUP I, cholesterol-free rabbit chow for 12 weeks; GROUP II, cholesterol-free chow, 40 weeks; GROUP III, chow supplemented with 2% cholesterol, 12 weeks; GROUP IV, chow supplemented with 2% cholesterol, 40 weeks. At the 12 and 40 weeks time points, animals in each of the aforementioned cohorts were subjected to echocardiographic measurements, followed by sacrifice. Significant deterioration in major outcome variables measured in the present study were observed only in animals maintained for 40 weeks on 2% cholesterol-supplemented chow, with much lesser adverse effects noted in animals fed high cholesterol diets for only 12 weeks. It was observed that rabbits receiving high cholesterol diets for 40 weeks exhibited significantly increased mortality, worsened ejection fraction and general deterioration of cardiac functions, along with increased atherosclerotic plaque formation and infarct size. Additionally, myocardium of GROUP IV animals was observed to contain lower levels of heme oxygenase-1 (HO-1) and cytochrome c oxidase III (COX III) protein relative to the controls.

Proximal tubule H-ferritin mediates iron trafficking in acute kidney injury

Ferritin plays a central role in iron metabolism and is made of 24 subunits of 2 types: heavy chain and light chain. The ferritin heavy chain (FtH) has ferroxidase activity that is required for iron incorporation and limiting toxicity. The purpose of this study was to investigate the role of FtH in acute kidney injury (AKI) and renal iron handling by using proximal tubule-specific FtH-knockout mice (FtH(PT-/-) mice). FtH(PT-/-) mice had significant mortality, worse structural and functional renal injury, and increased levels of apoptosis in rhabdomyolysis and cisplatin-induced AKI, despite significantly higher expression of heme oxygenase-1, an antioxidant and cytoprotective enzyme. While expression of divalent metal transporter-1 was unaffected, expression of ferroportin (FPN) was significantly lower under both basal and rhabdomyolysis-induced AKI in FtH(PT-/-) mice. Apical localization of FPN was disrupted after AKI to a diffuse cytosolic and basolateral pattern. FtH, regardless of iron content and ferroxidase activity, induced FPN. Interestingly, urinary levels of the iron acceptor proteins neutrophil gelatinase-associated lipocalin, hemopexin, and transferrin were increased in FtH(PT-/-) mice after AKI. These results underscore the protective role of FtH and reveal the critical role of proximal tubule FtH in iron trafficking in AKI.

Ethanol increases phosphate-mediated mineralization and osteoblastic transformation of vascular smooth muscle cells

Vascular calcification is implicated in the pathogenesis of atherosclerosis, diabetes and chronic kidney disease. Human vascular smooth muscle cells (HSMCs) undergo mineralization in response to elevated levels of inorganic phosphate (Pi) in an active and well-regulated process. This process involves increased activity of alkaline phosphatase and increased expression of core binding factor α-1 (CBF-α1), a bone-specific transcription factor, with the subsequent induction of osteocalcin. It has been shown that heavy alcohol consumption is associated with greater calcification in coronary arteries. The goal of our study was to examine whether ethanol alters mineralization of HSMCs provoked by high Pi. Exposure of HSMCs to ethanol increased extracellular matrix calcification in a dose responsive manner, providing a significant additional calcium deposition at concentrations of ≥60 mmol/l. HSMC calcification was accompanied by further enhancement in alkaline phosphatase activity. Ethanol also provoked a significant increase in the synthesis of osteocalcin. Moreover, in cells challenged with ethanol the expression of CBF-α1, a transcription factor involved in the regulation of osteoblastic transformation of HSMCs, was elevated. The observed effects of ethanol were not due to alterations of phosphate uptake by HSMCs. We conclude that ethanol enhances Pi-mediated human vascular smooth muscle calcification and transition of these cells into osteoblast-like cells.

Evaluation of the metabolic changes during hemodialysis by signal averaged ECG

Cardiovascular diseases are frequent complications of end-stage kidney disease. The aim of the present study was to prove the arrhythmogenic effect of dialysis using signal averaged ECG. The ECG changes and laboratory parameters (sodium, potassium, urea and creatinine levels) were detected during hemodialysis treatment in 26 patients suffering from end-stage kidney disease. The tests and the ECG were performed four times, before (0. minute), during (at 15 and 90 min), and eventually after dialysis (at 240 min). The duration of the QRS complex, high-frequency low-amplitude signals (HFLA), and root-mean-square voltage of the terminal 40 ms of the filtered QRS (RMS) were determined. We considered test results to be positive when two of the three tested parameters were outside the normal range: QRS > 120 ms, RMS < 20 uV, HFLA > 39 ms. Signal averaged ECG was positive in two cases (8%) before and after the dialysis. The duration of the QRS-complex increased significantly during the dialysis (predialysis: 109 +/- 7.6 ms, postdialysis: 116 +/- 8.0 ms, p < 0.0001). Serum urea nitrogen (predialysis: 26.2 +/- 5.4, postdialysis: 11.4 +/- 3.3 mmol/l, p <0.0001) and serum creatinine levels (predialysis: 931 +/- 212, postdialysis: 434 +/- 120 micromol/I, p < 0.0001) decreased significantly during the treatment. Significant and continuous decrease in the potassium levels were detected (predialysis: 5.30 +/- 0.72, postdialysis: 3.91 +/- 0.42 mmol/I, p < 0.0001) during the dialysis. Serum sodium levels (predialysis: 139 +/- 2.7, postdialysis: 141.4 +/- 2.2 mmol/I) had not changed during the dialysis. A significant negative correlation was found between decreasing potassium levels and increasing QRS duration (r = - 0.48, p = 0.01). Our results support our primer assumption that the metabolic changes during dialysis treatment can lead to considerable risk of cardiac arrhythmias.

Histamine and H1 -histamine receptors faster venous circulation

The study has analysed the action of histamine in the rabbit venous system and evaluated its potential role in contraction during increased venous pressure. We have found that a great variety exists in histamine sensitivity and H(1) -histamine receptor expression in various types of rabbit veins. Veins of the extremities (saphenous vein, femoral vein, axillary vein) and abdomen (common iliac vein, inferior vena cava) responded to histamine by a prominent, concentration-dependent force generation, whereas great thoracic veins (subclavian vein, superior vena cavas, intrathoracic part of inferior vena cava) and a pelvic vein (external iliac vein) exhibited slight sensitivity to exogenous histamine. The lack of reactivity to histamine was not due to increased activity of nitric oxide synthase (NOS) or heme oxygenase-1. H(1) -histamine receptor expression of veins correlated well with the histamine-induced contractions. Voltage-dependent calcium channels mediated mainly the histamine-induced force generation of saphenous vein, whereas it did not act in the inferior vena cava. In contrast, the receptor-operated channels were not involved in this response in either vein. Tyrosine phosphorylation occurred markedly in response to histamine in the saphenous vein, but not in the inferior vena cava. Histamine induced a prominent ρ kinase activation in both vessels. Protein kinase C and mitogen-activated protein kinase (MAPK) were not implicated in the histamine-induced intracellular calcium sensitization. Importantly, transient clamping of the femoral vein in animals caused a short-term constriction, which was inhibited by H(1) -histamine receptor antagonist in vivo. Furthermore, a significantly greater histamine immunopositivity was detected in veins after stretching compared to the resting state. We conclude that histamine receptor density adapts to the actual requirements of the circulation, and histamine liberated by the venous wall during increased venous pressure contributes to the contraction of vessels, providing a force for the venous return.

Homocysteine metabolism in peripheral blood mononuclear cells: evidence for cystathionine beta-synthase activity in resting state

Activated peripheral blood mononuclear cells (PBMC) release homocysteine and possess cystathionine β-synthase (CBS) activity; however, it was thought that there is no CBS in resting state. Previously, we found that nickel decreased intracellular homocysteine concentration in un-stimulated (e.g. resting) PBMC, suggesting that resting PBMC might also have active homocysteine metabolism. Here, we demonstrated that un-stimulated PBMC synthesize (incorporate L-[methyl-14C]methionine to DNA, lipids and proteins), release (increase extracellular homocysteine), and metabolize homocysteine. Intracellular homocysteine concentration varied with incubation time, depending on extracellular concentrations of methionine, homocysteine, and glutathione. Methionine synthase activity was constant and independent of thiol concentrations. In Western blot, CBS protein was clearly identified in freshly isolated PBMC. CBS protein level and activity increased with incubation time, upon stimulation, and similar to intracellular homocysteine, depending on intra- and extracellular homocysteine and glutathione concentrations. According to our knowledge, this is the first evidence that certifies homocysteine metabolism and regulatory role of CBS activity to keep balanced intracellular homocysteine level in resting PBMC. Homocysteine, released by PBMC, in turn can modulate its functions contributing to the development of hyperhomocysteinemia-induced diseases.

Heme degradation and vascular injury

Heme is an essential molecule in aerobic organisms. Heme consists of protoporphyrin IX and a ferrous (Fe(2+)) iron atom, which has high affinity for oxygen (O(2)). Hemoglobin, the major oxygen-carrying protein in blood, is the most abundant heme-protein in animals and humans. Hemoglobin consists of four globin subunits (alpha(2)beta(2)), with each subunit carrying a heme group. Ferrous (Fe(2+)) hemoglobin is easily oxidized in circulation to ferric (Fe(3+)) hemoglobin, which readily releases free hemin. Hemin is hydrophobic and intercalates into cell membranes. Hydrogen peroxide can split the heme ring and release "free" redox-active iron, which catalytically amplifies the production of reactive oxygen species. These oxidants can oxidize lipids, proteins, and DNA; activate cell-signaling pathways and oxidant-sensitive, proinflammatory transcription factors; alter protein expression; perturb membrane channels; and induce apoptosis and cell death. Heme-derived oxidants induce recruitment of leukocytes, platelets, and red blood cells to the vessel wall; oxidize low-density lipoproteins; and consume nitric oxide. Heme metabolism, extracellular and intracellular defenses against heme, and cellular cytoprotective adaptations are emphasized. Sickle cell disease, an archetypal example of hemolysis, heme-induced oxidative stress, and cytoprotective adaptation, is reviewed.

Oxidized hemoglobin is an endogenous proinflammatory agonist that targets vascular endothelial cells

Several pathologic conditions are associated with hemolysis, i.e. release of ferrous (Fe(II)) hemoglobin from red blood cells. Oxidation of cell-free hemoglobin produces (Fe(III)) methemoglobin. More extensive oxidation produces (Fe(III)/Fe(IV) O) ferryl hemoglobin. Both cell-free methemoglobin and ferryl hemoglobin are thought to contribute to the pathogenesis of hemolytic disorders. We show hereby that ferryl hemoglobin, but not hemoglobin or methemoglobin, acts as a potent proinflammatory agonist that induces vascular endothelial cells in vitro to rearrange the actin cytoskeleton, forming intercellular gaps and disrupting the integrity of the endothelial cell monolayer. Furthermore, ferryl hemoglobin induces the expression of proinflammatory genes in endothelial cells in vitro, e.g. E-selectin, Icam-1, and Vcam-1, through the activation of the nuclear factor kappaB family of transcription factors. This proinflammatory effect, which requires actin polymerization, involves the activation of the c-Jun N-terminal kinase and the p38 mitogen-activated protein kinase signal transduction pathways. When administered to naïve mice, ferryl hemoglobin induces the recruitment of polymorphonuclear cells, demonstrating that it acts as a proinflammatory agonist in vivo. In conclusion, oxidized hemoglobin, i.e. ferryl hemoglobin, acts as a proinflammatory agonist that targets vascular endothelial cells.

Diagnostic strategies used in primary care

The strategies used by general practitioners in making a diagnosis are being formally recognised; this article is the first in a series that will illustrate their application, and is accompanied by a case study (doi:10.1136/bmj.b1187)

Relationship between serum nickel and homocysteine concentration in hemodialysis patients

Severe hyperhomocysteinemia (HHC) is associated with atherosclerosis. In hemodialysis (HD) patients, one of the main causes of death is cardiovascular disease. In animals, trace elements such as cobalt, copper, iron, and nickel ameliorated vitamin B(12) deficiency-induced HHC. However, correlations between plasma total homocysteine (tHcy) and trace elements in HD patients have not been investigated. Therefore, tHcy, folate, vitamin B(12), trace elements (cobalt, copper, iron, and nickel), and some laboratory parameters such as serum total protein, albumin, transferrin, ferritin, C-reactive protein (CRP), and interleukin-6 concentrations were determined in 122 hemodialysis patients. When patients were divided into groups according to their tHcy, we found no significant differences in concentrations of cobalt, copper, and total protein, while nickel was higher, and folate, vitamin B(12), and iron were lower in patients with lower than higher tHcy. In univariate regression analysis, tHcy negatively correlated with concentrations of folate (r = -0.302, p < 0.006), vitamin B(12) (r = -0.347, p < 0.0001), nickel (r = -0.289, p < 0.006), and CRP (r = -0.230, p < 0.02) and positively with serum albumin (r = 0.316, p < 0.0004) and hemoglobin (r = 0.329, p < 0.0001) values. No relationship between tHcy and serum concentrations of cobalt, copper, iron, or other laboratory parameters was found in HD patients. The effect of cobalt and nickel on homocysteine production was assessed in human peripheral mononuclear cells (PBMCs). Nickel but not cobalt at concentrations found in HD patients significantly inhibited homocysteine, cysteine, and S-adenosylhomocysteine production in human PBMCs. These results suggest that nickel might also be involved in the regulation of the methionine-folate cycle in humans, as was demonstrated in animal experiments.

Comparative studies of differential expression of chitinolytic enzymes encoded by chiA, chiB, chiC and nagA genes in Aspergillus nidulans

N-Acetyl-D-glucosamine, chito-oligomers and carbon starvation regulated chiA, chiB, and nagA gene expressions in Aspergillus nidulans cultures. The gene expression patterns of the main extracellular endochitinase ChiB and the N-acetyl-beta-D-glucosaminidase NagA were similar, and the ChiB-NagA enzyme system may play a morphological and/or nutritional role during autolysis. Alterations in the levels of reactive oxygen species or in the glutathione-glutathione disulfide redox balance, characteristic physiological changes developing in ageing and autolyzing fungal cultures, did not affect the regulation of either the growth-related chiA or the autolysis-coupled chiB genes although both of them were down-regulated under diamide stress. The transcription of the chiC gene with unknown physiological function was repressed by increased intracellular superoxide concentration.

Effects of tocopherols and 2,2'-carboxyethyl hydroxychromans on phorbol-ester-stimulated neutrophils

Tocopherol vitamers [e.g., alpha-, gamma- and delta-tocopherol (alpha-TOC, gamma-TOC and delta-TOC, respectively)] and their water-soluble 2,2'-carboxyethyl hydroxychroman metabolites (e.g., alpha-, gamma- and delta-CEHC) all possess antioxidant properties. As a consequence, and similarly to other natural antioxidants, vitamin E compounds may be useful in preventing inflammatory and oxidative-stress-mediated diseases. In this study, we investigated the concentration-dependent effect of tocopherols and water-soluble metabolites on a key event in oxidative stress, for example, the oxidative burst in neutrophils. It was found that not only alpha-TOC but also gamma-TOC and delta-TOC as well as alpha-, gamma- and delta-CEHC at physiological concentrations inhibit superoxide anion (O2(*-)) production in phorbol-ester-stimulated neutrophils. This effect was mediated by the inhibition of the translocation and activation of protein kinase C (PKC) enzyme, which is the key event in the phorbol-ester signaling. Importantly, CEHCs were stronger inhibitors of PKC as compared with the vitamer precursors, and the gamma forms of both tocopherol and CEHC showed the highest inhibitory activities. Tocopherols, but not CEHCs, directly inhibit the fully activated nicotine-adenine-dinucleotide phosphate (NADPH) oxidase. However, none of the test compounds was able to directly scavenge O2(*-) when tested in a cell-free system. In conclusion, vitamin E compounds can control the neutrophil oxidative burst through the negative modulation of PKC-related signaling and NADPH oxidase activity. As an original finding, we observed that CEHC metabolites might contribute to regulate PKC activity in these cells. These results may have important implications in the anti-inflammatory and antioxidant role of vitamin E compounds.

Once-Monthly Subcutaneous C.E.R.A. Maintains Stable Hemoglobin Control in Patients with Chronic Kidney Disease on Dialysis and Converted Directly from Epoetin One to Three Times Weekly

BACKGROUND

C.E.R.A., a continuous erythropoietin receptor activator, is in development to provide anemia correction and stable maintenance of hemoglobin (Hb) levels at extended administration intervals in patients with chronic kidney disease (CKD). This study examined its efficacy and safety when administered up to once monthly in patients who have CKD and are on dialysis and randomly convert directly from epoetin alpha or beta one to three times weekly.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

In this three-arm, comparator-controlled, open-label, randomized, parallel-group, Phase III study, 572 dialysis patients (> or =18 yr) who were receiving stable subcutaneous epoetin one to three times weekly were randomly assigned (1:1:1) to continue epoetin or to receive subcutaneous C.E.R.A. once monthly or twice monthly for 52 wk. Dosage was adjusted to maintain Hb +/-1.0 g/dl of baseline level. Primary end point was mean change in Hb level between baseline and the evaluation period (weeks 29 to 36).

RESULTS

Mean Hb levels during the evaluation period were similar between groups (once-monthly C.E.R.A. 11.5 g/dl; twice-monthly C.E.R.A. 11.7 g/dl; epoetin 11.5 g/dl). The difference between C.E.R.A. and epoetin in mean change (97.5% confidence interval) in Hb concentration between baseline and evaluation was -0.022 g/dl (-0.262 to 0.217) for once monthly and 0.141 g/dl (-0.098 to 0.380) for twice monthly. Analysis demonstrated that C.E.R.A. was as effective as epoetin in maintaining Hb and was well tolerated.

CONCLUSIONS

Subcutaneous C.E.R.A. once or twice monthly successfully maintained tight and stable Hb levels in patients who were on dialysis and randomly converted directly from epoetin one to three times weekly.

Iron homeostasis in chronic inflammation

Inflammation induced anemia and resistance to erythropoietin are common features in patients with chronic kidney disease (CKD). Elevated levels of cytokines and enhanced oxidative stress, conditions associated with inflammatory states, are implicated in the development of anemia. Accumulating evidence suggests that activation of cytokine cascade and the associated acute-phase response, as it often occurs in patients with CKD, divert iron from erythropoiesis to storage sites within the reticuloendothelial system leading to functional iron deficiency and subsequently to anemia or resistance to erythropoietin. Other processes have also been shown to be involved in the pathogenesis of anemia provoked by the activated immune system including an inhibition of erythroid progenitor proliferation and differentiation, a suppression of erythropoietin production and a blunted response to erythropoietin. The present review concerns the underlying alterations in iron metabolism induced by chronic inflammation that result in anemia.

Atorvastatin prevents hypoxia-induced inhibition of endothelial nitric oxide synthase expression but does not affect heme oxygenase-1 in human microvascular endothelial cells

Beneficial cardiovascular effects of statins, the inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are particularly assigned to the modulation of inflammation. Endothelial nitric oxide synthase (eNOS) and heme oxygenase-1 (HO-1) are listed among the crucial protective, anti-inflammatory genes in the vasculature. Here we show that atorvastatin at pharmacologically relevant concentration (0.1 microM) enhanced the expression of eNOS in human microvascular endothelial cells (HMEC-1). Moreover, atorvastatin prevented hypoxia-induced decrease in eNOS expression. However, in the same cells atorvastatin was ineffective in modulation of HO-1 protein level. Therefore, we suggest that the protective effect of statins at their pharmacological concentrations is not mediated by enhancement of HO-1 activity, but may involve eNOS.

Oxidative stress and non-enzymatic glycation in IgA nephropathy

AIM

Approximately 20-50% of IgA nephropathy patients develop end-stage renal disease. We have previously found enhanced oxidative stress and decreased antioxidant capacity in red blood cells of IgA nephropathy patients. In this study we assess oxidative stress, non-enzymatic glycation, oxidative resistance of low-density lipoprotein and its alpha-tocopherol content in these patients.

PATIENTS AND METHODS

Non-enzymatic glycation and oxidative stress were assessed in 88 IgA nephropathy patients by measuring advanced glycation end products, Nepsilon-carboxymethyl-lysine, thiobarbituric acid reactive substances, oxidative resistance of low-density lipoprotein and its alpha-tocopherol content.

RESULTS

Advanced glycation end products (2659 +/- 958 a.u.) and Nepsilon-carboxymethyl-lysine (563 +/- 215 ng/ml) were significantly higher in IgA nephropathy patients with decreased renal function compared to those with normal renal function (p < 0.002) or controls (p < 0.001). Thiobarbituric acid-reactive substances in plasma and associated with low-density lipoprotein were significantly elevated and oxidative resistance of low-density lipoprotein was significantly reduced in all groups of IgA nephropathy patients. There was no significant difference in circulating fluorescent advanced glycation end products, Nepsilon-carboxymethyl-lysine, thiobarbituric acid-reactive substances levels, oxidative resistance of low-density lipoprotein and its alpha-tocopherol content between patients with normal vs. impaired glucose metabolism. Low alpha-tocopherol content of low-density lipoprotein was accompanied with decreased oxidative resistance, depletion in polyunsaturated fatty acids, elevated saturated fatty acids and thiobarbituric acid-reactive substances within low-density lipoprotein suggesting enhanced lipid peroxidation.

CONCLUSIONS

Decreased oxidative resistance of low-density lipoprotein and enhanced oxidative stress are common features in IgA nephropathy, while increased non-enzymatic glycation occurs as renal function declines.

Hyperleptinemia is not responsible for decreased paraoxonase activity in hemodialysis patients

BACKGROUND

Exogenous leptin markedly decreased plasma paraoxonase (PON1) activity in rats. Hyperleptinemia and decreased PON1 activity have previously been demonstrated in uremia. Therefore, we investigated the relationship between leptin level and PON1 activity in hemodialysis (HD) patients.

METHODS

Leptin and PON1 were determined in 40 HD patients and 40 age-matched controls with similar body mass index (BMI).

RESULTS

Leptin was higher (p < 0.001) and PON1 activity was lower (p < 0.001) in HD patients than in controls. PON1 and PON1/HDL ratio was higher in HD patients with BMI >25 kg/m2 than in HD patients with BMI <25 kg/m2. It was not due to a difference in frequency of high activity phenotype of PON1 among subgroups of HD patients. There was no similar difference in controls. Spearman analysis showed a significant correlation between leptin and PON1 activity (p < 0.02), BMI (p < 0.001), triglyceride (TG) (p < 0.03), and Kt/V (-0.323, p < 0.03), but multiparametric regression analysis did not reveal it. PON1 activity depended on BMI in both models. In controls, leptin correlated with BMI (p < 0.001) and TG (p < 0.002) but not PON1 activity. A slight decrease in leptin concentration and PON1 activity during HD was observed.

CONCLUSION

Our results suggest the role of other pathophysiological conditions besides hyperleptinemia resulting in decreased PON1 activity in HD patients.

Hemodialysis reduces inhibitory effect of plasma ultrafiltrate on LDL oxidation and subsequent endothelial reactions

Oxidative modification of low-density lipoprotein (LDL) and its deleterious effect on endothelium is implicated in the pathogenesis of atherosclerosis. Endothelium responds to such an insult by upregulating the synthesis of heme oxygenase-1 (HO-1) and ferritin. Endothelial cell damage and dysfunction have been observed in patients with chronic kidney disease (CKD) on maintenance hemodialysis (HD). We studied the effect of low-molecular-weight components of uremic plasma on LDL oxidation and LDL-oxidation-provoked endothelial cell reactions, such as the induction of cytotoxicity and the upregulation of cell-protective HO-1 and ferritin. Plasma ultrafiltrate (molecular weight<5000 Da) from CKD patients on HD or when treated conservatively exhibited a pronounced inhibition on heme-mediated oxidative modification of LDL. Endothelial cell cytotoxicity provoked by LDL oxidation was also attenuated by plasma ultrafiltrate from CKD patients. During HD treatment, a dramatic drop occurred in the retardation of oxidative reactions, and a loss of endothelial cytoprotection exerted by plasma ultrafiltrate was noted. The upregulation of HO-1 and ferritin in response to oxidative stress of LDL was blunted by uremic plasma ultrafiltrate that was released by the end of HD. The decreased antioxidant capacity of ultrafiltrate after HD occurred as a consequence of the intradialytic removal of L-ascorbic acid, uric acid, bilirubin, 3-indoxyl sulfate, indoxyl-beta-D-glucuronide, p-cresol, and phenol. Intradialytic removal of L-ascorbic acid, uric acid, bilirubin, 3-indoxyl sulfate, indoxyl-beta-D-glucuronide, p-cresol, and phenol increases the risk of LDL oxidation and subsequent endothelial cell damage, which underlines the importance of activation of cytoprotective HO-1 and ferritin in endothelium.

Structure prerequisite for antioxidant activity of silybin in different biochemical systems in vitro

Structural analogues (flavanone: 2-4 and flavone: 5 and 6, respectively) of silybin (1a) were synthesized and tested for inhibitory activity on O(2)(-) release and PKC translocation in PMA-stimulated neutrophils as well as xanthine oxidase activity in order to identify the molecular structures responsible for the antioxidant property of silybin. Concerning the prevention of hem-mediated oxidative modification of LDL by silybin, the hydroxyl radical scavenging activity of its structural analogues was also determined. We demonstrated that the basic skeleton of 1a (4) is responsible for its inhibitory activity on O(2)(-) release in PMA-stimulated neutrophils via inhibition of PKC translocation, since introduction of a double bound and hydroxyl groups at C-5 and C-7 position (5 and 6) did not result in further increase in inhibition of O(2)(-) release. It has been shown that the presence of the phenolic hydroxyl group at C-5 and C-7 of 1a is essential for the inhibition of xanthine oxidase activity. Moreover, introduction of a double bond into the C-ring of 2 and 3, resulting in flavone derivatives (5 and 6), markedly enhanced the antioxidant effect in all the tested systems. Finally, silybin (1a) and its flavon derivatives (5 and 6) directly scavenged hydroxyl radicals as well. On the basis of these results it might be concluded that different moiety of silybin is responsible for inhibition of overproduction of O(2)(-) in stimulated neutrophils, xanthine oxidase activity, and for prevention of hem-mediated oxidative modification of LDL.

Oxidation of hemoglobin by lipid hydroperoxide associated with low-density lipoprotein (LDL) and increased cytotoxic effect by LDL oxidation in heme oxygenase-1 (HO-1) deficiency

Heme-catalyzed oxidation of low-density lipoprotein (LDL) is one of the relevant mechanisms involved in LDL modification. We previously revealed a substantial oxidation of plasma hemoglobin to methemoglobin and a subsequent heme-catalyzed LDL oxidation generating moieties toxic to endothelium in heme oxygenase-1 (HO-1)-deficiency in human. Drawing upon our previous observation we posited a pathway for oxidation of plasma hemoglobin in the HO-1-deficient child involving LDL-associated lipid hydroperoxide. In support, LDL-associated lipid hydroperoxide oxidized ferrohemoglobin to methemoglobin--known to readily release its heme moieties--in a dose-dependent manner. Repeated heme exposure of the child s LDL further increased its lipid hydroperoxide content within min leading to additional cytotoxic effect on endothelium. Both cytotoxicity and HO-1 inducing ability of the oxidized LDL were strongly dependent on its lipid hydroperoxide content. We wondered if cells of the HO-1-deficient patient were prone to oxidative damage arising from heme-mediated oxidation of LDL. Indeed, we found elevated cytotoxicity induced by heme-catalyzed oxidation of LDL in lymphoblastoid cells derived from the HO-1-deficient patient. We conclude that oxidation of hemoglobin to methemoglobin by LDL-associated lipid hydroperoxide and increased sensitivity of cells of the HO-1-deficient child to stress of oxidized LDL might contribute to the vascular disorders reported earlier.

Inflammation and resistance to erythropoiesis-stimulating agents—what do we know and what needs to be clarified?

Resistance to erythropoiesis-stimulating agents (ESA) in patients with chronic kidney disease (CKD) can be associated with evidence of enhanced systemic inflammatory responses. This review considers the inflammatory mechanisms thought to be involved in the development and aetiology of anaemia of CKD that may help our understanding and management of patients with ESA resistance. The potential role of nutritional support and of anti-inflammatory therapies in managing resistance to ESA therapy is discussed and explored.

Effect of silybin on phorbol myristate actetate-induced protein kinase C translocation, NADPH oxidase activity and apoptosis in human neutrophils

Mechanism of the action of silybin (1) and its derivatives (2-4), possessing different lipid solubility in PMA-stimulated neutrophils was evaluated. Silybin (1) inhibited the calcium, phosphatidylserine- and diacylglycerol-dependent protein kinase C translocation and the NADPH oxidase activity in PMA-stimulated neutrophils and resulted in decreased apoptosis. Furthermore, silybin (1) inhibited xanthine oxidase activity and hem-mediated oxidative degradation of low-density lipoprotein, as well. Its derivatives (2-4), possessing different lipid-solubility, affected all the studied parameters. The lipid solubility of silybin (1) was enhanced by methylation (5'7'4''trimethylsilybin: 2), whereas a decrease in lipid-solubility by acetylation of compound 2 (5',7,'4"-trimethylsilybin-acetate: 3) or all the hydroxyl groups of silybin (peracetyl-silybin: 4) attenuated the antioxidant capacity by decreasing the inhibition in PKC translocation and NADPH oxidase activation. All the derivatives of silybin (2-4) showed no inhibition in cell free systems; e.g. did not alter the xanthine oxidase activity and the hem-mediated oxidative degradation of LDL. In conclusion, the antioxidant activity of (1) might be due to its ability to inhibit PKC translocation and NADPH oxidase activation in PMA-stimulated neutrophils. The increase of lipid solubility of silybin (1) supports its penetration through cell membrane and enhances its inhibitory effects. This structural modification of (1) might have pharmacological consequences.

Heme oxygenase-1-related carbon monoxide production and ventricular fibrillation in isolated ischemic/reperfused mouse myocardium

Heme oxygenase-1 (HO-1)-dependent carbon monoxide (CO) production related to reperfusion-induced ventricular fibrillation (VF) was studied in HO-1 wild-type (+/+), heterozygous (+/-), and homozygous (-/-) isolated ischemic/reperfused mouse heart. In HO-1 homozygous myocardium, under aerobic conditions, HO-1 enzyme activity, HO-1 mRNA, and protein expression were not detected in comparison with aerobically perfused wild-type and heterozygous myocardium. In wild-type, HO-1 hetero- and homozygous hearts subjected to 20 min ischemia followed by 2 h of reperfusion, the expression of HO-1 mRNA, protein, and HO-1 enzyme activity was detected in various degrees. A reduction in the expression of HO-1 mRNA, protein, and enzyme activity in fibrillated wild-type and heterozygous myocardium was observed. In reperfused/nonfibrillated wild-type and heterozygous hearts, a reduction in HO-1 mRNA, protein expression, and HO-1 enzyme activity was not observed, indicating that changes in HO-1 mRNA, protein, and enzyme activity could be related to the development of VF. These changes were reflected in the HO-1-related endogenous CO production measured by gas chromatography. In HO-1 knockout ischemic/reperfused myocardium, all hearts showed VF, and no detection in HO-1 mRNA, protein, and enzyme activity was observed. Thus, interventions that are able to increase endogenous CO may prevent the development of VF.