The effect of vitamin E on the antiphospholipid antibody title and on the incidence of thrombotic events in hemodialysis patients

The aim of the present study was to evaluate the effects of one year alpha-tocopherol oral administration on the antioxidant status, on anticardiolipin antibodies title and, finally, on the incidence of thrombosis in hemodialysis patients. Twenty-seven patients (mean age 59 years) with chronic renal failure, under chronic hemodialysis (mean duration in hemodialysis 46 months) were included into the study. Alpha-tocopherol at a dose of 500 mg daily was administered for a period of one year. Twenty patients undergoing hemodialysis (mean age 60 years, mean duration in hemodialysis 52 months) were receiving placebo during the same period of time. Patients with autoimmune disease, cancer or history of central or peripheral vascular disease were excluded, as well as, those who were receiving antiinflammatory or immunosupressive drugs. Twenty-two healthy volunteers (mean age 56 years) were the control group. Plasma total antioxidant status (TAS) and the activities of red cell`s antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) were assessed before and after a-tocopherol administration. Concurrently, serum IgG and IgM anticardiolipin antibodies (ACA-IgG and ACA-IgM) and the activities of the anticlotting proteins C and S were assessed. Thrombotic events were recorded for one year before, as well as, during the year of a-tocopherol administration. Results: 1. Plasma TAS was higher in hemodialysis patients compared with healthy volunteers. This is possibly due to the increased uric acid concentration in the patients with chronic renal failure plasma. No significant difference in SOD and GPx activities between hemodialysis patients and control group was found. Alpha-tocopherol administration decreased TAS and SOD activity. 2. There was statistically significant difference in ACA-IgG levels between hemodialysis patients and healthy volunteers. ACA-IgG levels were higher in hemodialysis patients compared with control group and were increased further after a-tocopherol administration. Alpha-tocopherol administration increased ACA-IgM levels too. ACA-IgG and ACA-IgM levels in patients who received placebo remained stable. 3. A statistically significant positive correlation was found between the decrease in TAS and the increase in ACA-IgG levels after a-tocopherol administration. 4. Protein C activity was decreased in hemodialysis patients compared with healthy volunteers. A-tocopherol administration did not influence protein C and S activities. 5. There was no significant difference in thrombotic events incidence before and after a-tocopherol administration. Additionally, there was no correlation between the ACA levels and the number of thrombotic events. Conclusions: 1. A-tocopherol can act, under special conditions, not as an antioxidant, but as a prooxidant. Excessive a-tocopherol intake, in combination with deficiency of other antioxidants, such as ascorbate, could result in conversion of the a-tocopherol from an antioxidant to a prooxidant. This is supported by the decreased TAS and SOD, as well as, by the increased ACA-IgG and ACA-IgM levels, that were induced by a-tocopherol administration in our study. 2. a-tocopherol administration increases ACA-IgG and ACA-IgM levels. ACA formation is probably the result of cardiolipin oxidation or cell death and cardiolipin release to the extracellular space. Oxidative stress can induce both of them. 3. Decreased anticlotting protein C activity in hemodialysis patients may contribute to the high incidence of thrombosis in these patients.Σκοπός της παρούσας μελέτης ήταν η διερεύνηση της επίδρασης της επί ένα έτος χορήγησης βιταμίνης Ε με τη μορφή της α-τοκο-φερόλης στo οξειδωτικό στρες, στον τίτλο των αντικαρδιολιπινικών αντισωμάτων, στη δραστηριότητα των πρωτεϊνών C και S και στη συχνότητα των θρομβωτικών επεισοδίων σε ασθενείς με χρόνια νε-φρική ανεπάρκεια τελικού σταδίου που υποβάλλονται σε αιμοκάθαρση. Για το σκοπό αυτό, στη μελέτη συμμετείχαν 27 ασθενείς μέσης ηλικίας 59 ετών που ήταν σε πρόγραμμα χρόνιας περιοδικής αιμοκά-θαρσης κατά μέσο όρο για 46 μήνες. Οι ανωτέρω έλαβαν για χρονικό διάστημα ενός έτους α-τοκοφερόλη σε δόση 500 mg την ημέρα. Συμμετείχαν επίσης 20 αιμοκαθαιρόμενοι ασθενείς μέσης ηλικίας 60 ετών με μέση διάρκεια στην αιμοκάθαρση 52 μήνες, οι οποίοι έλαβαν για το ίδιο χρονικό διάστημα placebo. Εξαιρέθηκαν της μελέτης ασθενείς με αυτοάνοσο νόσημα, ενεργό λοίμωξη, νεοπλασία, ή ιστορικό αγγειακής νόσου. Κανένας επίσης από τους ασθενείς που συμμετείχαν στη μελέτη δε λάμβανε αντιφλεγμονώδη ή ανοσοκατασταλτικά φάρμακα. Την ομάδα ελέγχου αποτέλεσαν 22 υγιείς εθελοντές μέσης ηλικίας 56 ετών, στους οποίους προσδιορίσθηκαν όλες οι παράμετροι της μελέτης. Στους ασθενείς της μελέτης, πριν και μετά από τη χορήγηση α-τοκοφερόλης ή placebo, προσδιορίσθηκαν η ολική αντιοξειδωτική ικα-νότητα (TAS) του πλάσματος, τα αντιοξειδωτικά ένζυμα υπεροξειδική δισμουτάση (SOD) και υπεροξειδάση της γλουταθειόνης των ερυθρών αιμοσφαιρίων (GPx), καθώς και ο τίτλος των αντικαρδιολιπινικών αντισωμάτων (ACA), τύπου IgG και IgM του ορού, και τέλος η δραστηριότητα των πρωτεϊνών C και S του πηκτικού μηχανισμού. Στους ασθενείς καταγράφηκαν επίσης τα θρομβωτικά επεισόδια που παρουσίασαν κατά τη διάρκεια του έτους πριν από την έναρξη της μελέτης και του έτους εκπόνησης της μελέτης. Αποτελέσματα: 1. Διαπιστώθηκε αυξημένη TAS του πλάσματος στους αιμοκαθαιρό-μενους ασθενείς σε σχέση με τους υγιείς μάρτυρες, εύρημα για το οποίο πιθανώς ευθύνονται τα υψηλά επίπεδα του ουρικού οξέος στο πλάσμα των ασθενών με χρόνια νεφρική ανεπάρκεια. Αντίθετα, δε βρέθηκε σημαντική διαφορά στη δραστηριότητα των αντιοξειδωτικών ενζύμων SOD και GPx των ερυθρών αιμοσφαι-ρίων μεταξύ ασθενών και υγιών μαρτύρων. Η λήψη α-τοκοφερό-λης ελάττωσε την TAS του πλάσματος, καθώς και τη δραστηριό-τητα της SOD. 2. Βρέθηκε σημαντική διαφορά στον τίτλο των ACA-IgG μεταξύ ασθενών και υγιών μαρτύρων. Ο τίτλος των ACA-IgG ήταν πολύ υψηλότερος στους ασθενείς που υποβάλλονται σε αιμοκάθαρση και παρουσίασε σημαντική περαιτέρω αύξηση μετά τη λήψη α-τοκοφερόλης. Αύξηση παρουσίασε επίσης και ο τίτλος των ACA-IgM στον ορό των ασθενών μετά τη λήψη α-τοκοφερόλης. Η ομάδα των ασθενών που έλαβε placebo δεν παρουσίασε μεταβολή των επιπέδων των ACA-IgG και ACA-IgM. 3. Παρατηρήθηκε στατιστικά σημαντική θετική συσχέτιση μεταξύ της ελάττωσης της TAS και της αύξησης του τίτλου των ACA-IgG από τη λήψη της α-τοκοφερόλης. 4. Διαπιστώθηκε ελαττωμένη δραστηριότητα της αντιπηκτικής πρω-τεΐνης C στους ασθενείς σε σχέση με τους υγιείς εθελοντές. Η λήψη α-τοκοφερόλης δε φάνηκε να επηρεάζει τη δραστηριότητα των πρωτεϊνών C και S. 5. Δε διαπιστώθηκε, τέλος, στατιστικά σημαντική διαφορά στη συχνότητα των θρομβωτικών επεισοδίων των ασθενών πριν και μετά από τη λήψη α-τοκοφερόλης, ούτε συσχέτιση του τίτλου των ACA-IgG και ACA-IgM με τον αριθμό των θρομβώσεων. Συμπεράσματα: 1. Η α-τοκοφερόλη μπορεί να έχει, κάτω από ορισμένες συνθήκες, οξειδωτική δράση, αντί της αναμενόμενης αντιοξειδωτικής. Η παρατεταμένη χορήγησή της φαίνεται να επιδρά αρνητικά στο οξειδωτικό ισοζύγιο των ασθενών υπό αιμοκάθαρση, σε συνδυ-ασμό βέβαια με την ένδεια άλλων αντιοξειδωτικών ουσιών, όπως το ασκορβικό οξύ. Οι τελευταίες είναι απαραίτητες για τη μετατροπή της οξειδωμένης στη μη οξειδωμένη μορφή της α-τοκοφερόλης και τη διατήρηση της αντιοξειδωτικής της δράσης. Η οξειδωτική δράση της α-τοκοφερόλης υποστηρίζεται από την ελάττωση της TAS και SOD, καθώς και από την αύξηση του τίτλου των ACA που προκάλεσε η α-τοκοφερόλη, όπως διαπιστώθηκε στην παρούσα μελέτη. 2. Η χορήγηση α-τοκοφερόλης, πιθανώς προάγοντας την οξείδωση των φωσφολιπιδίων, προκαλεί αύξηση του τίτλου των ACA-IgG και των ACA-IgM. Ο σχηματισμός των αντικαρδιολιπινικών αντι-σωμάτων είναι πιθανότατα αποτέλεσμα της οξείδωσης της καρδιο-λιπίνης ή κυτταρικού θανάτου και της απελευθέρωσής της στον εξωκυττάριο χώρο. Το οξειδωτικό στρες μπορεί να ευθύνεται και για τους δύο προτεινόμενους μηχανισμούς σχηματισμού των αντισωμάτων αυτών. 3. Η δραστηριότητα της αντιπηκτικής πρωτεΐνης C είναι ελαττωμένη στους αιμοκαθαιρόμενους ασθενείς, συμβάλοντας στη θρομβωτική διάθεση των ασθενών αυτών

Cell Death Patterns Due to Warm Ischemia or Reperfusion in Renal Tubular Epithelial Cells Originating from Human, Mouse, or the Native Hibernator Hamster

Ischemia⁻reperfusion injury contributes to the pathogenesis of many diseases, with acute kidney injury included. Hibernating mammals survive prolonged bouts of deep torpor with a dramatic drop in blood pressure, heart, and breathing rates, interspersed with short periods of arousal and, consequently, ischemia⁻reperfusion injury. Clarifying the differences under warm anoxia or reoxygenation between human cells and cells from a native hibernator may reveal interventions for rendering human cells resistant to ischemia⁻reperfusion injury. Human and hamster renal proximal tubular epithelial cells (RPTECs) were cultured under warm anoxia or reoxygenation. Mouse RPTECs were used as a phylogenetic control for hamster cells. Cell death was assessed by both cell imaging and lactate dehydrogenase (LDH) release assay, apoptosis by cleaved caspase-3, autophagy by microtubule-associated protein 1-light chain 3 B II (LC3B-II) to LC3B-I ratio, necroptosis by phosphorylated mixed-lineage kinase domain-like pseudokinase, reactive oxygen species (ROS) fluorometrically, and lipid peroxidation, the end-point of ferroptosis, by malondialdehyde. Human cells died after short periods of warm anoxia or reoxygenation, whereas hamster cells were extremely resistant. In human cells, apoptosis contributed to cell death under both anoxia and reoxygenation. Although under reoxygenation, ROS increased in both human and hamster RPTECs, lipid peroxidation-induced cell death was detected only in human cells. Autophagy was observed only in human cells under both conditions. Necroptosis was not detected in any of the evaluated cells. Clarifying the ways that are responsible for hamster RPTECs escaping from apoptosis and lipid peroxidation-induced cell death may reveal interventions for preventing ischemia⁻reperfusion-induced acute kidney injury in humans

Does hepcidin affect erythropoiesis in hemodialysis patients?

Introduction: Prohepcidin is the precursor of hepcidin, a liver-derived peptide involved in iron metabolism by blocking its intestinal absorption and its release by the reticuloendothelial system. Iron overload and inflammation increase hepcidin expression, whereas anemia and hypoxia suppress it. In the present study prohepcidin levels were determined in the serum of hemodialysis (HD) patients and its correlations with iron metabolism markers, C-reactive protein (CRP) and hematocrit (Hct) were assessed. Patients and Methods: Forty-sixHD patients and 22 healthy volunteers were enrolled in the study. Hct, serum prohepcidin, CRP, iron, ferritin, transferrin saturation and transferrin receptors were measured. The weekly erythropoietin dose, last-month intravenous iron dose and the patients' demographics were recorded. Results: In comparison to the healthy volunteers, the HD patients had higher serum ferritin, transferrin receptors and CRP, lower serum iron and similar transferrin saturation and prohepcidin levels. In the patient group prohepcidin levels were negatively correlated with Hct but not with any other of the examined parameters. Multiple linear regression analysis considering age, inflammation, iron adequacy, erythropoietin dose and prohepcidin levels revealed that prohepcidin was the predominant determinant of Hct. Conclusions: Taking into account the low Hct levels in the HD patients of our study, it seems plausible that the prohepcidin levels assessed in this group are inappropriately high. These functionally high prohepcidin levels may be associated with the factors that inhibit erythropoiesis in HD patients. On the other hand, the absence of other expected correlations indicates that further studies are needed in order to definitely clarify this aspect. Copyright © 2006 S. Karger AG

Malate dehydrogenase-2 inhibitor LW6 promotes metabolic adaptations and reduces proliferation and apoptosis in activated human T-cells

Activated T cells rely on aerobic glycolysis and glutaminolysis in order to proliferate and differentiate into effector cells. Therefore, intervention in these metabolic pathways inhibits proliferation. The aim of the present study was to evaluate the effects of Krebs' cycle inhibition at the level of malate dehydrogenase‑2 (MDH2) in human activated T cells using the MDH2 inhibitor LW6. Activated T cells from healthy volunteers were cultured in the presence or absence of LW6 and cytotoxicity, cell proliferation and the expression levels of hypoxia‑inducible factor (HIF)‑1α, c‑Myc, p53, cleaved caspase‑3 and certain enzymes involved in glucose metabolism and glutaminolysis were evaluated. The results revealed that LW6 was not toxic and decreased apoptosis and the levels of the pro‑apoptotic tumor suppressor p53. In addition, LW6 inhibited T‑cell proliferation and decreased the levels of c‑Myc, HIF‑1α, glucose transporter‑1, hexokinase‑II, lactate dehydrogenase‑A and phosphorylated pyruvate dehydrogenase. By contrast, LW6 increased the levels of pyruvate dehydrogenase. These alterations may lead to decreased production of pyruvate, which preferentially enters into the Krebs' cycle. Furthermore, LW6 decreased the levels of glutaminase‑2, while increasing those of glutaminase‑1, which may preserve glutaminolysis, and possibly pyruvate‑malate cycling, potentially protecting the cells from energy collapse. In summary, the inhibition of MDH2 in activated T cells abrogates proliferation without adversely affecting cell survival. Adaptations of cellular glucose and glutamine metabolism may prevent energy collapse. © 2015, Spandidos Publications. All rights reserved

Plasma Indoleamine 2,3-Dioxygenase Concentration is Increased in Hemodialysis Patients and May Contribute to the Pathogenesis of Coronary Heart Disease

Introduction: Coronary heart disease (CHD) is the leading cause of death in hemodialysis (HD) patients. Inflammation contributes to the pathogenesis of atherosclerosis in this population. Indoleamine 2,3-dioxygenase (IDO), an enzyme with immunomodulatory properties, was evaluated in HD patients with or without CHD. Methods: Of the total of 66 HD patients, 22 of them with CHD were confirmed by coronary angiography and 24 healthy volunteers were enrolled in the study. Plasma IDO was assessed by means of enzyme-linked immunosorbent assay. Serum interleukin-6 (IL-6) and C-reactive protein (CRP) were also measured. Results: Compared with healthy volunteers, plasma IDO concentration was markedly increased in HD patients (median 8.04 ng/mL vs. 48.9 ng/mL). Serum IL-6 and CRP were also significantly increased in HD patients. Compared with HD patients without CHD, plasma IDO concentration was significantly increased in HD patients with CHD (median 38.6 ng/mL vs. 74.5 ng/mL). Neither IL-6 nor CRP differed between the last two groups. IDO was negatively correlated with IL-6 and CRP. Conclusion: IDO concentration is increased in HD patients and is increased further in HD patients with CHD. It remains to be elucidated if increased IDO plays a direct role in the pathogenesis of atherosclerosis or if it affects atherosclerosis indirectly by curtailing chronic inflammation or both