Transcriptome-based identification of pro- and antioxidative gene expression in kidney cortex of nitric oxide-depleted rats.

Nitric oxide (NO) depletion in rats induces severe endothelial dysfunction within 4 days. Subsequently, hypertension and renal injury develop, which are ameliorated by alpha-tocopherol (VitE) cotreatment. The hypothesis of the present study was that NO synthase (NOS) inhibition induces a renal cortical antioxidative transcriptional response and invokes pro-oxidative and proinflammatory gene expression due to elimination of dampening effects of NO and enhanced oxidative stress. Male Sprague-Dawley rats received NOS inhibitor N(omega)-nitro-l-arginine (l-NNA, 500 mg/l water) for 4 (4d-LNNA), 21 (21d-LNNA), or 21 days with VitE in chow (0.7 g/kg body wt/day). Renal cortical RNA was applied to oligonucleotide rat arrays. In 4d-LNNA, 21d-LNNA, and 21d-LNNA+VitE, 120, 320, and 184 genes were differentially expressed, respectively. Genes related to glutathione and bilirubin synthesis were suppressed during 4d and 21d-LNNA and not corrected by VitE. Proteinuria, tubulointerstitial macrophages, and heme-oxygenase-1 (HO-1) expression were strongly correlated. Remarkably, pro-oxidative genes were not induced. Inflammation- and injury-related genes, including kidney injury molecule-1 and osteopontin, were unchanged at day 4, induced at 21d, and partly corrected by VitE. Superimposing HO-1 inhibition on NOS inhibition had no impact on the development of hypertension. To summarize, renal expression of genes involved in synthesis of the antioxidants glutathione and bilirubin seemed directly NO dependent, but there were no direct effects of NO depletion on pro-oxidant systems. This indicates that renal transcriptional regulation of two defense systems, glutathione and bilirubin syntheses, seems to depend upon adequate NO synthesis. Interaction between NO synthesis and heme degradation pathways for blood pressure regulation was not found.

Sympathetic hyperactivity in haemodialysis patients is reduced by short daily haemodialysis.

OBJECTIVE: Haemodialysis patients often have sympathetic hyperactivity. The hypothesis of this study was that a switch from three times weekly to short daily dialysis could affect sympathetic hyperactivity. METHODS: We studied 11 patients (eight men; aged 46 +/- 8 years) stable on haemodialysis for at least 1 year before and 6 months after conversion from three times to six times weekly dialysis without increasing total dialysis time (short daily dialysis). Seven patients were restudied 2 months after switching back to three times weekly haemodialysis. RESULTS: Ultrafiltration volume per session decreased from 2.4 +/- 1.0 to 1.5 +/- 0.6 l (P < 0.05). The extracellular fluid volume (bromide distribution space) did not change. Mean arterial pressure (without medication) decreased from 113 +/- 11 to 98 +/- 9 mmHg (P < 0.05). Cardiac output (Doppler echocardiography) did not change, but peripheral vascular resistance decreased from 25.4 +/- 6.4 to 21.2 +/- 3.2 mmHg per min/l (P < 0.05), in conjunction with a decrease in muscle sympathetic nerve activity (MSNA) from 39 +/- 19 to 28 +/- 15 bursts/min (P < 0.05). Ambulant 24 h blood pressure decreased and the nocturnal blood pressure dip increased during short daily dialysis. The seven patients who were switched back to alternate day haemodialysis showed a return of the high MSNA and peripheral vascular resistance. CONCLUSION: The study shows that sympathetic hyperactivity in haemodialysis patients is reduced by increasing the frequency of treatment sessions. This is probably because of the decrease in number or magnitude of the fluid fluctuations.

Water immersion in preeclampsia.

OBJECTIVE: Preeclampsia is associated with profound vasoconstriction in most organ systems and reduced plasma volume. Because water immersion produces a marked central redistribution of blood volume and suppresses the renin-angiotensin system response and sympathetic activity, we hypothesized that water immersion might be useful in the treatment of preeclampsia. STUDY DESIGN: The effects of thermoneutral water immersion for 3 hours on central and peripheral hemodynamics were evaluated in 7 preeclamptic patients, 7 normal pregnant control patients, and 7 nonpregnant women. Finger plethysmography was used to determine hemodynamic measurements (cardiac output and total peripheral resistance), and forearm blood flow was measured by strain gauge plethysmography. Postischemic hyperemia was used to determine endothelium-dependent vasodilation. Analysis was by analysis of variance for repeated measurements. RESULTS: During water immersion cardiac output increased while diastolic blood pressure and heart rate decreased, although systolic blood pressure remained unchanged in each group. Forearm blood flow increased significantly in the normal pregnant and preeclamptic subjects. Total peripheral resistance decreased in all groups, but values in preeclamptic patients remained above those of normotensive pregnant women. Water immersion had no effect on endothelium-dependent vasodilation in the preeclamptic group, and most hemodynamic changes that were observed reversed to baseline within 2 hours of completion of the procedure. CONCLUSION: Although water immersion results in hemodynamic alterations in a manner that is theoretically therapeutic for women with preeclampsia, the effect was limited and short-lived. In addition water immersion had no effect on endothelium-dependent vasodilation in women with preeclampsia. The therapeutic potential for water immersion in preeclampsia appears to be limited.

Anti-oxidant sensitivity of donor age-related gene expression in cultured fibroblasts.

Cultured human fibroblasts display age-dependent transcriptomic differences. We hypothesized that aging-associated oxidative stress affects gene expression, and monitored the transcriptome in confluent fibroblasts from young and old individuals cultured without and with a lipophilic and hydrophilic anti-oxidant mixture (vitamin E, quercetin, hydroxytyrosol and kaempferol). In cells derived from old subjects genes with lower expression were related to oxidative stress, growth and differentiation, cell cycle or metabolic enzymes and with higher expression to protein processing and docking, extracellular matrix, immune response, EGF-signalling and transcription. Anti-oxidant treatment modulated a similar number of genes in all donors and induced cell cycle regulatory genes. A subset of genes, modulated by age and inversely modulated by anti-oxidants, included glutaminase. Despite increased glutaminase expression, donor age-dependent decline in glutathione content and resistance to glutathione-depletion was observed. Summarizing, gene expression of fibroblasts is affected by donor age and a subset was corrected by anti-oxidants. Thus, in cultured fibroblasts from aged donors, gene expression is partly driven by oxidative stress.

Arterial stiffness and fetal growth in normotensive pregnancy.

BACKGROUND: Normal pregnancy is characterized by a decrease in peripheral resistance and generalized vasodilation resulting in plasma volume expansion, which is associated with intrauterine growth. Stiffness of the arterial system may be a measure of the degree of plasma volume expansion. Pulse wave velocity (PWV), measured by applanation tonometry, is a validated approach to determine arterial stiffness. Pulse pressure (PP) is considered a surrogate measure for arterial stiffness. The aim of this study was to evaluate the association between arterial stiffness and fetal growth. METHODS: In 50 normotensive pregnancies, carotid-femoral PWV was measured in the third trimester in 30 degrees lateral position. Blood pressure measurements were performed with conventional auscultatory sphygmomanometry. Birth weight centiles and weight centiles at the age of 6 months were recorded. Linear regression models were used for statistical analyses. RESULTS: There was a significant relationship in PWV with both birth weight centiles and catch-up growth after birth, independent of mean arterial pressure (MAP). An increase of 1 m/sec in PWV was associated with a decrease in birth weight centiles by 17.6% and a catch-up of 22.3% in weight centiles after birth. A stronger association was found for pulse pressure and birth weight centiles. An increase of 1 mm Hg was associated with a decrease in birth weight centiles by 1.8%. There was no association between MAP and birth weight centiles. CONCLUSIONS: In normotensive pregnancy arterial stiffness is associated with birth weight centile and catch-up growth after birth, independently from MAP. This suggests that arterial stiffness reflects maternal vascular adaptation to pregnancy better than blood pressure.

Gene expression of energy and protein metabolism in hearts of hypertensive nitric oxide- or GSH-depleted mice.

Hypertension demands cardiac synthetic and metabolic adaptations to increased afterload. We studied gene expression in two models of mild hypertension without overt left ventricular hypertrophy using the NO synthase inhibitor nitro-L-arginine (L-NNA) and the glutathione depletor buthionine-S,R-sulfoximine (BSO). Mice were administered L-NNA, BSO, or water for 8 weeks. RNA of left ventricles was pooled per group, reverse transcribed, Cy3 and Cy5 labeled, and hybridized to cDNA microarrays. Normalized log(2) Cy3/Cy5 ratios of > or =0.7 or < or =-0.7 were considered significant. L-NNA and BSO both caused hypertension. Gene expression was regulated in cytoskeletal components in both models, protein synthesis in L-NNA-treated mice, and energy metabolism in BSO-treated mice. Energy metabolism genes shared several common transcription factor-binding sites such as Coup-Tf2, of which gene expression was increased in BSO-treated mice, and COMP-1. Characterization of the left ventricular adaptations as assessed with gene expression profiles reveals differential expression in energy and protein metabolism related to the pathogenetic background of the hypertension.

Endothelial function in pediatric patients on peritoneal dialysis: the need for data.

Cardiovascular complications are emerging as the primary cause of death for patients with childhood end-stage renal disease. Children with end-stage renal failure are subjected to many of the risk factors for cardiovascular disease identified in adult patients. Dysfunction of the endothelium is presently regarded as a first but reversible step in the development of atherosclerosis. Noninvasive techniques to assess endothelial function have been recently developed and have been proven to predict future mortality in adult patients. These techniques are readily applicable to pediatric patients. Endothelial dysfunction has been demonstrated in children in all stages of renal failure. Data on pediatric patients treated with peritoneal dialysis are currently lacking, however. Considering the abundance of cardiovascular risk factors specific to treatment with peritoneal dialysis, such studies should be initiated.

Validation and use of the Finometer for blood pressure measurement in normal, hypertensive and pre-eclamptic pregnancy.

OBJECTIVE: Although a large variety of automated blood pressure devices are available, only some have been validated for use in clinical practice. The British Hypertension Society (BHS) recommends separate validation of automated devices in special subgroups, e.g. the elderly and pregnant women. The aim of this study was to compare the Finometer (FM) and the earlier validated SpaceLabs 90207 (SL) with standard auscultatory blood pressure measurements in normal, pre-eclamptic and hypertensive pregnancy, following the guidelines of the BHS and the Association for the Advancement of Medical Instrumentation (AAMI). METHODS: The total study group consisted of 123 pregnant women, of whom were 54 normotensive, 31 pre-eclamptic and 38 hypertensive. Automated readings with the FM and SL were compared with auscultatory blood pressure measurements. Bland-Altman plots, BHS grades, mean pressure differences and 95% limits of agreement were used for analysis. RESULTS: Bland-Altman plots showed a wide scatter of the pressure differences between auscultatory and automated measurements. FM achieved BHS grades C/D, C/B, D/D and D/D in the total, normotensive, pre-eclamptic and hypertensive group, respectively. The AAMI criteria were only met for diastolic blood pressure in the normotensive group. For SL almost identical BHS grades and 95% limits of agreement as compared to our earlier study were found. CONCLUSIONS: The accuracy and precision of the Finometer are not sufficient for determination of absolute blood pressure levels in individual pregnant women. Our present findings on the SpaceLabs 90207 reconfirm our earlier results.

Different effects of tacrolimus and cyclosporine on renal hemodynamics and blood pressure in healthy subjects.

BACKGROUND: The side effects of cyclosporine, nephrotoxicity and hypertension, contribute to long-term renal graft failure and cardiovascular morbidity in graft recipients. It is not clear whether tacrolimus is as nephrotoxic and hypertensive as cyclosporine. Data on this subject are not consistent because of differences in dosage and duration of treatment and the presence of comorbidity in the studied patients. A comparison of both drugs with respect to renal hemodynamics and blood pressure has not been performed yet in healthy subjects. METHODS: We studied blood pressure, glomerular filtration rate, and effective renal plasma flow in eight healthy subjects at baseline and after 2 weeks administration of cyclosporine and tacrolimus, in randomized order. Trough levels of either drug were within the currently recommended therapeutical range of 100-200 ng/ml for cyclosporine and 5-15 ng/ml for tacrolimus. RESULTS: Tacrolimus did not influence renal hemodynamic parameters, in contrast to cyclosporine. During cyclosporine, glomerular filtration rate decreased from 98+/-9 ml/min/1.732 to 85+/-10 ml/min/1.732 (P<0.05), and ERPF decreased from 597+/-108 ml/min/1.732 to 438+/-84 ml/min/1.732 (P<0.01). Mean arterial blood pressure increased from 93+/-8 mmHg to 108+/-10 mmHg (P<0.05) during cyclosporine and remained unchanged during tacrolimus. CONCLUSIONS: We conclude that tacrolimus given during 2 weeks in the currently advised dosage has no unfavorable effects on renal hemodynamics and blood pressure in healthy individuals. The use of tacrolimus in organ transplant recipients may in the long-term lead to better renal function and less cardiovascular morbidity than the use of cyclosporine.

Vascular function in children after renal transplantation.

BACKGROUND: Atherosclerotic complications are the main cause of death in adult patients with renal failure. Endothelial dysfunction is a hallmark of early atherosclerotic changes. The numerous risk factors for endothelial dysfunction present in adults are present in children with renal failure, as well. In addition to this, increased stiffness of the arterial tree conveys an increased risk for cardiovascular mortality. The aim of this study is to investigate whether pediatric kidney recipients already show endothelial dysfunction and have increased arterial stiffness. METHODS: We investigated 20 pediatric kidney recipients with stable graft function and 20 healthy children. Endothelial function was studied noninvasively with ultrasound and digital signal analysis equipment as the percentage of post-ischemic flow-mediated dilatation (FMD) of the brachial artery. Parameters of arterial distensibility were calculated from distension of the brachial artery during the cardiac cycle, pulse pressure, and baseline diameter. RESULTS: FMD was significantly less in patients (7.7% +/- 5.4%) than controls (15.0% +/- 7.1%; P < 0.001), indicating endothelial dysfunction in pediatric kidney recipients. Impairment of FMD was found predominantly in patients being treated for hypertension. Arterial distensibility was diminished in patients (3.4 +/- 2.8 versus 5.7 +/- 3.3 10(-3)/mm Hg; P < 0.02), indicating increased stiffness of the arterial tree. Patients had a greater baseline diameter of the brachial artery adjusted for height than healthy controls at equal blood pressure. CONCLUSION: These findings suggest arterial wall changes in pediatric renal transplant recipients. They are already at risk for premature development of atherosclerotic complications and cardiovascular mortality.

Central hemodynamics of hypertensive disorders in pregnancy.

BACKGROUND: Preeclampsia is characterized by an increase in peripheral vasoconstriction. Studies of central hemodynamics are limited. Noninvasive evaluation of aortic stiffness and pressure waveform is possible by applanation tonometry. We determined pulse wave velocity (PWV), augmentation index (AI), subendocardial viability ratio (SEVR), and the central to brachial pressure amplification in normotensive, hypertensive, and preeclamptic pregnancies. METHODS: In 51 normotensive, 38 hypertensive, and 33 preeclamptic pregnancies we measured carotid-femoral PWV. The AI, SEVR, and central pressures were determined by analysis of the aortic pressure waveform derived from the radial artery. Measurements were performed in lateral position after 10 min of rest. Linear regression models and ANOVA multiple comparisons were used for statistical analyses. RESULTS: There were no differences in age or other baseline characteristics. The mean PWV for the normotensive, hypertensive, and preeclamptic groups was 5.1 m/sec (SD 0.6), 6.2 m/sec (SD 1.0), and 7.0 m/sec (SD 1.3), respectively. The AI was 6.7% (SD 14.0), 17.7% (SD 15.9), and 31.1% (SD 12.4), respectively. The SEVR was 1.38 (SD 0.2), 1.50 (0.2), and 1.48 (0.3), respectively. Central to brachial pressure amplification was 1.6 (SD 0.2), 1.4 (SD 0.2), and 1.3 (SD 0.2), respectively. After adjustment for blood pressure, no significant differences remained between the groups. CONCLUSIONS: In hypertensive and preeclamptic pregnancies, aortic stiffness and augmentation are significantly higher as compared to normotensive pregnancy. Amplification of central pulse pressure is significantly lower in hypertensive and preeclamptic pregnancies, resulting in relatively higher central pressure. Nevertheless, the supply and demand ratio of the heart is not impaired in hypertensive and preeclamptic pregnancies.

Hypertriglyceridemia in patients with chronic renal failure: possible mechanisms.

Cardiovascular disease (CVD) is a major cause of mortality in patients with chronic renal failure (CRF) caused by numerous factors defined as traditional and uremia-related risk factors. One of these risk factors, dyslipidemia, is often observed in patients with CRF, resulting in abnormal concentrations and composition of plasma lipoproteins. The prominent features of uremic dyslipidemia are an increase in plasma triglycerides and cholesterol in nearly all lipoproteins, and a reduction in high-density lipoprotein (HDL) cholesterol. Because of its direct contact with the circulating blood, the endothelium is preferentially subjected to the modulatory effects of these altered lipoproteins. Little is known about the mechanisms for hypertriglyceridemia in CRF. This review highlights several studies over the past years that have contributed to knowledge of hypertriglyceridemia, especially in combination with renal diseases and their dialysis treatment. The underlying mechanisms behind hypertriglyceridemia have not been fully clarified and may indeed be multifactorial. Hypertriglyceridemia may contribute to the progression of atherosclerosis. Therefore, it is essential to study the putative mechanisms for uremic dyslipidemia, since optimal treatment is essential for the prevention or delay of cardiovascular complications in patients with CRF.

Human proximal tubular cell responses to angiotensin II analyzed using DNA microarray.

Angiotensin II has been shown to exert complex effects on proximal tubular cell function and growth. To assess some of the direct effects on proximal tubular cells, changes in gene expression of selected cellular pathways were determined after exposure to angiotensin II. We used DNA microarrays to analyze multiple gene expression responses to increasing angiotensin II concentrations. Human proximal tubular cells were grown in flasks, and the presence of angiotensin type 1 receptor was confirmed by Western blot analysis. At passages 4-6, these cells were exposed to angiotensin II and harvested 4 h later and mRNA of the cells was extracted; 2 microg of mRNA was fluorescently conjugated for cDNA microarray hybridization. A custom-made DNA microarray was designed by selecting 300 human genes from 10 different functional systems and amplifying clones using polymerase chain reaction. Cells were subjected to 10 and 100 nM angiotensin II with paired untreated cells as controls. RNA was isolated, reverse transcribed, labeled and hybridized to the arrays and the ratios calculated. Ratios of > or =2.0 and < or =0.5 were considered significant. Coordinated changes were observed in genes of the hepatocyte nuclear factor 3 family (NHF3; HNF3A, HNF3B and HNF3G), in the E2F genes (E2F1, E2F3) and the interferon regulatory factors IRF1 and IRF5. Induction of the expression of transcription factors points towards complex regulation of gene expression upon angiotensin II exposure. Three genes involved in the dampening of oxidative stress were enhanced. Taken together, brief exposure of human tubular epithelial cells to angiotensin II elicited a marked induction of nuclear factors, antioxidant genes and hormones and hormone receptor genes. The quick activation of transcription factors by angiotensin II indicates that angiotensin II can directly initiate a cascade of expressional events in proximal tubular cells.

The benefit of STent placement and blood pressure and lipid-lowering for the prevention of progression of renal dysfunction caused by Atherosclerotic ostial stenosis of the Renal artery. The STAR-study: rationale and study design.

BACKGROUND: Atherosclerotic renal artery stenosis (ARAS) is associated with progressive loss of renal function and is one of the most important causes of renal failure in the elderly. Current treatment includes restoration of the renal arterial lumen by endovascular stent placement. However, this treatment only affects damage caused by ARAS due to the stenosis and ensuing post-stenotic ischemia. ARAS patients have severe general vascular disease. Atherosclerosis and hypertension can also damage the kidney parenchyma causing renal failure. Medical treatment focuses on the latter. Lipid-lowering drugs (statins) could reduce renal failure progression and could reduce the overall high cardiovascular risk. The additional effect on preserving renal function of stent placement as compared to medical therapy alone is unknown. Therefore, the STAR-study aims to compare the effects of renal artery stent placement together with medication vs. medication alone on renal function in ARAS patients. METHOD: Patients with an ARAS of > or = 50% and renal failure (creatinine (Cr) clearance < 80 mL/min/1.73 m2) are randomly assigned to stent placement with medication or to medication alone. Medication consists of statins, anti-hypertensive drugs and antiplatelet therapy. Patients are followed for 2 yrs with extended follow-up to 5 yrs. The primary outcome of this study is a reduction in Cr clearance > 20% compared to baseline. This trial will include 140 patients.

Chronic kidney disease after myeloablative allogeneic hematopoietic stem cell transplantation.

Because survival of recipients of allogeneic hematopoietic stem cell transplantation (HSCT) has improved, long-term complications become more important. We studied the incidence and risk factors of chronic kidney disease in these patients and evaluated associated posttransplant complications and mortality. We performed a retrospective cohort study of 266 adults who received myeloablative allogeneic HSCT and who survived for >6 months in an 11-year period at a Dutch university medical center. Primary outcome was the incidence of chronic kidney disease defined as a glomerular filtration rate (GFR) of <60 mL/min/1.73 m(2). Chronic kidney disease developed in 61 (23%) of 266 patients, with a cumulative incidence rate of 27% at 10 years. Severe kidney disease (GFR of <30 mL/min/1.73 m(2)) developed in 3% of patients. Only 6 patients developed the thrombotic microangiopathic syndrome SCT nephropathy, and 2 of them needed dialysis. Pretransplant risk factors for chronic kidney disease were lower GFR at day 0 (P < .0001, odds ratio [OR] 0.95 95% confidence interval [CI] 0.93-0.97), female gender, and higher age (P = .001 and P < .0001, respectively). The occurrence of hypertension after transplantation was associated with chronic kidney disease (P < .0001, OR 0.34 95% CI 0.18-0.62). Mortality was 39% after a mean follow-up of 5.1 years. There was no significant difference in survival between patients with and without chronic kidney disease. Chronic kidney disease is a common late complication of myeloablative allogeneic HSCT. Because of the natural decline in renal function with time there is a risk of developing end-stage renal disease in the future. SCT nephropathy seems to be a specific cause of chronic kidney disease that is typically associated with severe kidney disease.

Sympathetic hyperactivity in hypertensive chronic kidney disease patients is reduced during standard treatment.

Standard treatment in chronic kidney disease (CKD) patients includes an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker. CKD is often characterized by sympathetic hyperactivity. This study investigates the prevalence of sympathetic hyperactivity (quantified by assessment of muscle sympathetic nerve activity [MSNA]) in a sizable group of patients with CKD and assessed whether chronic angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker normalizes increased MSNA. In 74 CKD patients (creatinine clearance 54+/-31 mL/min), MSNA, blood pressure, and plasma renin activity were measured in the absence of antihypertensive drugs except for diuretics. In a subgroup of 31 patients, another set of measurements was obtained after > or =6 weeks of enalapril (10 mg PO), losartan (100 mg PO), or eprosartan (600 mg PO). Patients as compared with control subjects (n=82) had higher mean arterial pressure (113+/-13 versus 89+/-7 mm Hg), MSNA (31+/-13 versus 19+/-7 bursts per minute), and log plasma renin activity (2.67+/-036 versus 2.40+/-0.32 fmol/L per second; all P<0.001). During angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker therapy (n=31), mean arterial pressure (115+/-11 to 100+/-9 mm Hg) and MSNA (33+/-11 to 25+/-9 bursts per minute) decreased (both P<0.01) but were still higher than in control subjects (both P<0.01). Multiple regression analysis identified age and plasma renin activity as predictive for MSNA. In conclusion, sympathetic hyperactivity occurs in a substantial proportion of hypertensive CKD patients. Angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker treatment reduces but does not normalize MSNA.

Met-RANTES reduces endothelial progenitor cell homing to activated (glomerular) endothelium in vitro and in vivo.

The chemokine RANTES (regulated upon activation normal T-cell expressed and secreted) is involved in the formation of an inflammatory infiltrate during glomerulonephritis. However, RANTES receptor inhibition, although reducing glomerular leukocyte infiltration, can also increase damage. We hypothesized that RANTES does not only promote the influx and activation of inflammatory leukocytes but also mediates glomerular microvascular repair by stimulating the homing of bone marrow (BM)-derived endothelial progenitor cells. To investigate the role of RANTES in the participation of BM-derived cells in glomerular vascular repair, we used a rat BM transplantation model in combination with reversible anti-Thy-1.1 glomerulonephritis. Twenty-four hours after the induction of glomerulonephritis, BM-transplanted rats were treated for 7 days with either the RANTES receptor antagonist Met-RANTES or saline. The participation of BM-derived endothelial cells in glomerular repair, glomerular monocyte infiltration, and proteinuria was evaluated at days 7 and 28. Furthermore, we used an in vitro perfusion chamber assay to study the role of RANTES receptors in shear-resistant adhesion of the CD34+ stem cells to activated endothelium under flow. In our reversible glomerulonephritis model, RANTES receptor inhibition specifically reduced the participation of BM-derived cells in glomerular vascular repair by more than 40% at day 7 without impairing monocyte influx. However, no obvious change in recovery from proteinuria or morphological damage was observed. Blockade of RANTES receptors on CD34+ cells in vitro partially inhibited platelet-enhanced, shear-resistant firm adhesion of the CD34+ cells to activated endothelium. In conclusion, our data suggest that RANTES is involved in the homing and participation of BM-derived endothelial cells in glomerular repair.

End-stage renal disease causes an imbalance between endothelial and smooth muscle progenitor cells.

Patients with end-stage renal disease (ESRD) on hemodialysis have an increased risk of cardiovascular disease (CVD). Circulating endothelial progenitor cells (EPC) contribute to vascular regeneration and repair, thereby protecting against CVD. However, circulating smooth muscle progenitor cells (SPC) may contribute to adverse vascular remodeling. We hypothesized that an imbalance occurs between EPC and SPC in ESRD patients and sampled progenitor cells from 45 ESRD patients receiving regular treatment. Our study is the first to show reduced numbers of CD34+KDR+ hematopoietic stem cell (HSC)-derived EPC (type I EPC). Furthermore, monocyte-derived EPC cultured from mononuclear cells (type II EPC) were reduced in number and had a reduced capacity to stimulate endothelial cell angiogenesis. In contrast, SPC outgrowth was unaffected. In vitro incubation with uremic serum impaired type II EPC outgrowth from healthy donor mononuclear cells and did not influence SPC outgrowth. The hemodialysis procedure itself induced HSC apoptosis and caused an acute depletion of circulating EPC. Taken together, the decreased number and impaired function of EPC are compatible with impaired endogenous vascular repair in hemodialysis patients, whereas the unaffected SPC numbers suggest that the potential of progenitor cells to contribute to adverse remodeling is retained. This EPC-SPC imbalance may contribute to the acceleration of CVD in ESRD patients and could offer novel therapeutic targets.

Haematopoietic and endothelial progenitor cells are deficient in quiescent systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is associated with a high prevalence of cardiovascular disease. Circulating endothelial progenitor cells (EPCs) contribute to vascular regeneration and repair, thereby protecting against atherosclerotic disease. EPCs are derived from CD34+ haematopoietic stem cells (HSCs), which have an increased propensity for apoptosis in the bone marrow of patients with SLE. AIM: To determine whether circulating HSCs and EPCs are reduced in SLE, contributing to an increased cardiovascular risk. METHODS: Progenitor cells were sampled from 15 female patients with SLE in prolonged clinical remission from their disease and 15 matched healthy controls. HSC and CD34+KDR+ EPCs were quantified by flow cytometry. Annexin V staining was used to identify apoptotic cells. RESULTS: Patients with SLE had reduced levels of circulating CD34+ HSCs and CD34+KDR+ EPCs, associated with increased HSC apoptosis. Compared with controls, the fraction of HSCs that could be identified as EPCs was higher in patients with SLE, consistent with a primary defect of HSCs. EPC outgrowth from mononuclear cells, which depends mainly on CD34- cells, was unaffected. CONCLUSIONS: Patients with SLE have lower levels of circulating HSCs and EPCs, even during clinical remission. The data suggest that increased HSC apoptosis is the underlying cause for this depletion. These observations indicate that progenitor cell-mediated endogenous vascular repair is impaired in SLE, which may contribute to the accelerated development of atherosclerosis.

Maternal supplementation with citrulline increases renal nitric oxide in young spontaneously hypertensive rats and has long-term antihypertensive effects.

NO deficiency is associated with development of hypertension. Defects in the renal citrulline-arginine pathway or arginine reabsorption potentially reduce renal NO in prehypertensive spontaneously hypertensive rats (SHRs). Hence, we investigated genes related to the citrulline-arginine pathway or arginine reabsorption, amino acid pools, and renal NO in 2-week-old prehypertensive SHRs. In addition, because perinatally supporting NO availability reduces blood pressure in SHRs, we supplemented SHR dams during pregnancy and lactation with citrulline, the rate-limiting amino acid for arginine synthesis. In female offspring, gene expression of argininosuccinate synthase (involved in renal arginine synthesis) and renal cationic amino acid Y-transporter (involved in arginine reabsorption) were both decreased in 2-day and 2-week SHRs compared with normotensive WKY, although no abnormalities in amino acid pools were observed. In addition, 2-week-old female SHRs had much less NO in their kidneys (0.46+/-0.01 versus 0.68+/-0.05 nmol/g of kidney weight, respectively; P<0.001) but not in their heart. Furthermore, perinatal supplementation with citrulline increased renal NO to 0.59+/-0.02 nmol/g of kidney weight (P<0.001) at 2 weeks and persistently ameliorated the development of hypertension in females and until 20 weeks in male SHR offspring. Defects in both the renal citrulline-arginine pathway and in arginine reabsorption precede hypertension in SHRs. We propose that the reduced cationic amino acid transporter disables the developing SHR kidney to use arginine reabsorption to compensate for reduced arginine synthesis, resulting in organ-specific NO deficiency. This early renal deficiency and its adverse sequels can be corrected by perinatal citrulline supplementation persistently in female and transiently in male SHRs.