Jens Passauer

Endothelial dysfunction in patients with rheumatoid arthritis is associated with a reduced number and impaired function of endothelial progenitor cells

Background: Rheumatoid arthritis (RA) is associated with increased morbidity and mortality attributable to accelerated atherosclerosis and cardiovascular events. Objective: To determine the role played by endothelial progenitor cells (EPC) in the defence system against arteriosclerosis. Methods: The number and function of EPC in 13 young patients with RA with low disease activity (DAS28 3.5 (0.3)) and 13 healthy control subjects was studied. Endothelial function was investigated by agonist-induced, endothelium dependent vasodilatation measured by the forearm blood flow technique. Migratory activity and adhesion of EPC to tumour necrosis factor α (TNFα) activated mature endothelial cells and components of the extracellular matrix were tested in vitro. Putative precursor populations (CD34+, CD34+/CD133+, and CD34+/KDR+ haematopoietic stem cells) were measured by flow cytometric analysis. Results: Acetylcholine-induced, endothelium dependent vasodilatation was reduced by about 50% in patients with RA, indicating endothelial dysfunction, whereas endothelium-independent vasodilatation in response to glyceryl trinitrate was at control level. Significantly reduced numbers of EPC were found in the patients compared with controls. Migratory activity of EPC was decreased in patients with RA. Adhesion to mature endothelial cells after activation with TNFα was enhanced only in controls. The adhesion to matrix proteins and the number of putative precursor cell lineages was comparable in both groups. Conclusion: Endothelial dysfunction in patients with RA with low grade inflammation is associated with a reduced number and partial dysfunction of EPC. Further studies are needed to explore whether interventions that potentially ameliorate the number and function of EPC also improve endothelial function in these patients.

Endothelial dysfunction in young patients with long-term rheumatoid arthritis and low disease activity

OBJECTIVE Cardiovascular mortality is excessive in patients with rheumatoid arthritis (RA). It has been proposed that the chronic inflammatory state of RA contributes to accelerated atherosclerosis. The aim of this study was to determine whether endothelial dysfunction, an early sign of arteriosclerosis, is present in young, long-term RA patients receiving standard methotrexate (MTX) therapy. Furthermore, we tested whether etanercept (ENC), a TNF-alpha receptor blocker, resulted in improved endothelial function compared to MTX in the same patients. METHODS We studied eight RA patients twice: (1) on MTX and (2) after MTX washout and receiving ENC. Eight healthy volunteers matching for age, gender, height, weight and conventional cardiovascular risk factors served as control (C). All participants received intrabrachial infusions of increasing doses of acetylcholine (ACh, endothelium-dependent vasodilator) and glyceryl-trinitrate (GTN, endothelium-independent vasodilator). Forearm blood flow (FBF) was measured by bilateral venous occlusion plethysmography. RESULTS Disease activity of RA was comparably low during both MTX and ENC (DAS 28 3.9+/-0.3 and 3.5+/-0.3). FBF in response to ACh was reduced in RA compared to C (P<0.01). Switching from MTX to ENC failed to improve vascular responsiveness to ACh. GTN comparably increased FBF in all groups. CONCLUSIONS Our study for the first time demonstrates that long-term RA is associated with manifested endothelial dysfunction. Switching from MTX to ENC in stable RA patients has no beneficial effect on endothelial function.

Evaluation of clinical dry weight assessment in haemodialysis patients using bioimpedance spectroscopy: a cross-sectional study

BACKGROUND Dry weight assessment (DWA) is essential to efficient therapy of haemodialysis (HD) patients. However, so far objective methods for DWA have not been applicable to daily routine. Thus, exact fluid management in HD remains difficult and is often based on clinical criteria. The aims of this study were (1) to objectively define pre- and post-dialytic ranges of extracellular volume in a large cohort of HD patients (in whom DWA had been defined according to clinical criteria), (2) to compare the hydration status between diabetic and non-diabetic patients, and (3) to assess a patient subgroup that might benefit from correction of target weight. METHODS We measured fluid overload (FO) prior to a mid-week HD session in 370 randomly selected HD patients (50% with diabetes) from five dialysis centres. A new bioimpedance spectroscopy (BIS) device that implies a validated body composition model was applied. This tool allows correct quantification of extracellular FO or - deficiency in comparison to a healthy reference population (normal range -1.1 to 1.1 L according to the 10th and 90th percentile of measurements). In addition, weight and blood pressure were recorded before and after treatment. RESULTS Pre-dialytic FO ranged from -0.5 to 4 L and post-dialytic FO from -2.5 to 2 L (10th and 90th percentile of measurements), indicating that on average the hydration status of healthy subjects is considered as the optimal target weight in HD patients. Comparison of FO between diabetic and non-diabetic patients revealed no difference. Based on the consideration that an FO < -1.1 L before and >1.1 L after HD indicates inadequate DWA, we identified 98 (26%) patients who might benefit from correction of target body weight. CONCLUSION BIS is an interesting, objective method to support clinical DWA. Further studies should be performed to investigate beneficial clinical effects of this approach.

Reduced Agonist-Induced Endothelium-Dependent Vasodilation in Uremia Is Attributable to an Impairment of Vascular Nitric Oxide

Current concepts for the explanation of endothelial dysfunction and accelerated atherosclerosis in uremia propose a reduced vascular bioavailability of nitric oxide (NO). The aim of the present study was to test the contributions of NO and NO/prostacyclin (PGI(2))-independent mechanisms to both baseline vascular tone and agonist-induced endothelium-dependent vasodilation in patients on hemodialysis (HD). In 10 HD patients and eight matched healthy control subjects, forearm blood flow (FBF) was measured at rest and during intrabrachial infusions of norepinephrine (NE; endothelium-independent vasoconstrictor, 60, 120, and 240 pmol/min) and N-monomethyl-L-arginine (blocker of NO synthases, 16 micromol/min). After inhibition of cyclo-oxygenase by ibuprofen (1200 mg orally), endothelium-dependent and -independent vasodilation was assessed by infusion of acetylcholine (ACh; 1, 5, 10, 50, 100, and 300 nmol/min) and sodium-nitroprusside (2.5, 5, and 10 microg/min). NO/PGI(2)-independent vasodilation was tested by equal infusions of ACh during NO clamp. N-monomethyl-L-arginine reduced resting FBF to a comparable degree in both groups. Vascular responses to ACh were reduced in HD (P = 0.003 versus control by ANOVA), whereas those to sodium nitroprusside were mainly at control level. Infusion of ACh during NO clamp caused a similar increment of FBF in both groups. NO-mediated vasodilation as calculated by the difference between ACh-induced responses without and with NO clamp was substantially impaired in HD (P < 0.001) compared with control. In HD patients, baseline NO-mediated arteriolar tone is at control level. This study provides first evidence that endothelial dysfunction of uremic patients as shown by reduced agonist-induced endothelium-dependent vasodilation is attributable to reduced stimulation of NO, whereas the NO/PGI(2)-resistant portion of ACh-mediated vasodilation is unaffected.

Baseline blood flow and bradykinin-induced vasodilator responses in the human forearm are insensitive to the cytochrome P450 2C9 (CYP2C9) inhibitor sulphaphenazole.

A substantial portion of the vasodilator response elicited by bradykinin in the human forearm is unaffected by the combined inhibition of nitric oxide (NO) synthases and cyclo-oxygenases. The cytochrome P450 (CYP) 2C9 inhibitor sulphaphenazole was recently identified as a potent inhibitor of NO- and prostacyclin (PGI2)-independent relaxation in porcine coronary arteries. The aim of the present study was to determine the effect of sulphaphenazole on basal and bradykinin-induced NO/PGI2-independent changes in the forearm blood flow (FBF) of healthy subjects. Eleven healthy male volunteers participated in this placebo-controlled study. Test agents were infused into the brachial artery and FBF was measured by bilateral venous occlusion plethysmography. Sulphaphenazole (0.02-2 mg/min) alone did not affect basal blood flow. Inhibition of the NO synthases by NG-monomethyl-L-arginine (L-NMMA; 4 micromol/min) and cyclo-oxygenases by ibuprofen (1200 mg, orally) reduced FBF to 48 +/- 7% in the absence and 50 +/- 8% in the presence of sulphaphenazole (2 mg/min; P=not significant). After pretreatment with L-NMMA (16 micromol/min) and ibuprofen (1200 mg, orally), sulphaphenazole (6 mg/min) did not substantially inhibit bradykinin-induced vasodilation. We conclude that CYP2C9-derived metabolites (i) are not involved in the regulation of baseline blood flow, and (ii) do not mediate bradykinin-induced NO/PGI2-independent vasorelaxation in the human forearm. However, determining the contribution of this enzyme to regulation of blood flow in pathological conditions associated with endothelial dysfunction requires further studies.

Kidney transplantation improves endothelium-dependent vasodilation in patients with endstage renal disease.

Kidney transplantation (Tx) improves the cardiovascular outcome of patients receiving hemodialysis (HD). Therefore, we asked whether Tx improves the endothelial dysfunction of HD patients. Eight patients were studied twice: (1) during HD and (2) after Tx. We also studied eight matched control subjects. We measured forearm blood flow by venous occlusion plethysmography. We administered intrabrachial infusions of three doses of norepinephrine, glycerol trinitrate, acetylcholine (ACH), and N-monomethyl-L-arginine. The response to ACH was reduced in HD patients compared with controls (P <0.001). The response to ACH in HD patients improved after Tx, and this change was significant for low-dose ACH (P <0.05 for dose one and two compared with HD). The response to glycerol trinitrate, which was reduced in HD patients compared with controls (P <0.01), remained unchanged after Tx. N-monomethyl-L-arginine and norepinephrine comparably reduced forearm blood flow in all groups. This is the first evidence showing an improvement of endothelial dysfunction in HD patients after Tx.

Why an apheresis center should offer more than one lipoprotein apheresis method.

We describe our experience with the performance of six lipoprotein apheresis methods (HELP, TheraSorb LDL, DALI, lipidfiltration, Liposorber D, MONET) which have been used in 68 patients. Thirty‐four of them have been treated with more than one method. The calculations presented in this paper are based on laboratory data measured at the last three available apheresis sessions before the switch to another method and at the end of the observation period, respectively. With respect to the reduction of low‐density lipoprotein (LDL) cholesterol, DALI and Liposorber D appeared to be the most effective lipoprotein apheresis methods, for reduction of lipoprotein(a), Liposorber D. Data on the influence of these lipoprotein apheresis methods on parameters of the coagulation system (prothrombin time, international normalized ratio, activated partial thromboplastin time, fibrinogen) are also reported. The histories of three patients who have been switched to several lipoprotein apheresis methods are given as examples. The major reason for switching was the low efficiency of a given lipoprotein apheresis method with respect to lowering of LDL cholesterol; the reason for this phenomenon was not clear in each case. In three patients who took an oral anticoagulant and were treated with HELP, the influence on the coagulation system is reported; they were submitted to another apheresis method. In two patients we observed an allergy to heparin—they were then treated with a heparin‐free apheresis method. In conclusion, we point out that there are several reasons why an apheresis center should offer more than one lipoprotein apheresis method.

Role of rho-kinase in the regulation of vascular tone in hypertensive renal transplant recipients.

Activation of rho-kinase (ROK) is involved in the development of hypertension as it is a potent regulator of vascular smooth muscle cell (VSMC) contractility. Here we evaluated whether activation of ROK is present in hypertensive kidney transplant recipients (NTX). We tested the effect of the ROK-inhibitor fasudil on the regulation of forearm blood flow (FBF) in NTX and in healthy control subjects (CTL). In addition potential modulating effects of ROK-inhibition on local vascular nitric oxide (NO) release were studied. The effect of intra-arterial infusion of fasudil on FBF was studied by venous-occlusion plethysmography in NTX and CTL. To unmask the role of NO fasudil was infused with/without clamping of vascular NO in NTX and CTL. To unravel the basal NO-mediated tone the NO-synthase inhibitor l-NMMA was infused. Fasudil markedly but comparably increased FBF in NTX and CTL. The vascular response to fasudil was blunted during NO-clamp in CTL (104+/-18% vs. 244+/-48% for NO-clamp+fasudil vs. fasudil alone; baseline=0%, P<0.05) but not in NTX. The l-NMMA-induced vasoconstriction was impaired in NTX compared to CTL. In NTX and CTL basal vascular tone equally depends on ROK. Fasudil-induced vasodilatation is partly mediated by vascular NO in CTL but not in NTX. The greater NO-insensitive fasudil-induced increase in FBF in NTX suggests an increased ROK-mediated VSMC constrictor tone in these patients. Basal NO-mediated tone is attenuated in hypertensive NTX.

Differential effects of lipoprotein apheresis by lipidfiltration or dextran sulfate adsorption on lipidomic profile

OBJECTIVE AND METHODS Acute modification of plasma lipidomic profile was assessed by top-down shotgun profiling on a LTQ Orbitrap hybrid mass spectrometer in 14 patients treated with two different apheresis techniques: plasma lipidfiltration (LF) and whole blood dextran sulfate adsorption (DSA). RESULTS Patients treated with DSA revealed a significantly more pronounced reduction of LDL-cholesterol (LDL-C), a diminished decrease of HDL-cholesterol (HDL-C) and triglycerides (TG), and a similar reduction in lipoprotein (a) (Lp(a)) level. Against the overall tendency of reduction of lipid metabolites of all lipid classes in post-apheresis plasma, independent of apheresis technology applied, a highly significant increase of phosphatidylethanolamines (PE) in response to DSA was observed. CONCLUSION These data indicate that DSA technology may be associated with an activation or damage of blood cells at contact surface which subsequently leads to a massive liberation of cellular and membrane PEs. Pathophysiological consequences, especially with respect to coagulation system and oxidative stress, have to be further elucidated.

Current situation of lipoprotein apheresis in Saxony

This paper summarizes the situation pertinent to treatment via lipoprotein apheresis in the federal state of Saxony, Germany in 2010. In total, 119 predominately male patients were treated in 10 centers; the majority of the patients was older than the mean age of the general population. Several risk factors were present, particularly a familial predisposition and hypertension. All patients had experienced cardiovascular events and the majority was taking statins. Patient data from the University Hospital Carl Gustav Carus in Dresden concurred with data derived from patients treated at nephrological practices. In the mean, patients attended the centers for about 6 years, the majority weekly. LDL cholesterol concentrations prior to apheresis were clearly higher than target levels; apheresis sessions decreased LDL cholesterol by 69%. Lipoprotein(a) levels could be measured in 75 patients and were effectively reduced by lipoprotein apheresis. In Saxony, 29 patients per 1 million inhabitants received lipoprotein apheresis, which is higher than the proportion of patients treated in Germany as a whole. The need for this extracorporeal treatment seems to be much greater than its current utilization. Among the patients only one homozygous patient with familial hypercholesterolemia was observed. Physicians should be actively informed about this therapeutic possibility to reduce the cardiovascular risk efficiently. The introduction of new drugs may alter the position of lipoprotein apheresis within the therapeutic spectrum.