Polycystin deficiency induces dopamine-reversible alterations in flow-mediated dilatation and vascular nitric oxide release in humans.

Autosomal dominant polycystic kidney disease (ADPKD) is a renal hereditary disorder associated with increased cardiovascular mortality, due to mutations in polycystin-1 and polycystin-2 genes. Endothelial polycystin-deficient cells have an altered mechanosensitivity to fluid shear stress and subsequent deficit in calcium-induced nitric oxide release, prevented by dopamine receptor stimulation. However, the impact of polycystin deficiency on endothelial function in ADPKD patients is still largely unknown. Here we assessed endothelium-dependent flow-mediated dilatation in 21 normotensive ADPKD patients and 21 healthy control subjects, during sustained (hand skin heating) and transient (postischemic hyperemia) flow stimulation. Flow-mediated dilatation was less marked in ADPKD patients than in controls during heating, but it was similar during postischemic hyperemia. There was no difference in endothelium-independent dilatation in response to glyceryl trinitrate. Local plasma nitrite, an indicator of nitric oxide availability, increased during heating in controls but not in patients. Brachial infusion of dopamine in a subset of ADPKD patients stimulated plasma nitrite increase during heating and improved flow-mediated dilatation. Thus, ADPKD patients display a loss of nitric oxide release and an associated reduction in endothelium-dependent dilatation of conduit arteries during sustained blood flow increase. The correction of these anomalies by dopamine suggests future therapeutic strategies that could reduce the occurrence of cardiovascular events in ADPKD.

High-efficiency on-line haemodiafiltration improves conduit artery endothelial function compared with high-flux haemodialysis in end-stage renal disease patients.

BACKGROUND: Middle molecular weight uraemic toxins are considered to play an important role in vascular dysfunction and cardiovascular outcomes in end-stage renal disease (ESRD) patients. Recent dialysis techniques based on convection, specifically high-efficiency on-line haemodiafiltration (HDF), enhance the removal of middle molecular weight toxins and reduce all-cause mortality in haemodialysis (HD) patients. However, the mechanisms of these improved outcomes remain to be established. METHODS: This prospective study randomly assigned 42 ESRD patients to switch from high-flux HD to high-efficiency on-line HDF (n=22) or to continue HD (n=20). Brachial artery endothelium-dependent flow-mediated dilatation, central pulse pressure, carotid artery intima-media thickness (IMT), internal diastolic diameter and distensibility and circulating markers of uraemia, inflammation and oxidative stress were blindly assessed before and after a 4-month follow-up. RESULTS: Brachial flow-mediated dilatation and carotid artery distensibility increased significantly in the HDF group compared with HD, while carotid IMT and diameter remained similar. HDF decreased predialysis levels of the uraemic toxins ß2-microglobulin, phosphate and blood TNFα mRNA expression. Oxidative stress markers were not different between the HD and HDF groups. Blood mRNA expression of protein kinase C ß2, an endothelial NO-synthase (eNOS) inhibitor, decreased significantly with HDF. CONCLUSIONS: High-efficiency on-line HDF prevents the endothelial dysfunction and stiffening of the conduit arteries in ESRD patients compared with high-flux HD. HDF decreases uraemic toxins, vascular inflammation, and is associated with subsequent improvement in eNOS functionality. These results suggest that reduced endothelial dysfunction may be an intermediate mechanism explaining the beneficial outcomes associated with HDF.

Syngeneic bone marrow cell therapy prevents intimal proliferation in allogeneic vascular transplantation.

BACKGROUND: Transplant arteriosclerosis is characterized by intraluminal obstructive proliferation occurring in response to immune-mediated arterial wall injury. Cell therapy with vascular progenitor cells have been suggested to repair intimal lesions following endothelial injury. The aim of the current study was to assess the effects of autologous bone marrow cell direct transfer and of Fucan-mobilization bone marrow-derived progenitor cells on intimal thickening in vascular grafts. METHODS: Aortic allografts were performed in Brown Norway (BN) and Lewis (LEW) rats. Cell therapy was performed by injection of two doses of 10 million LEW bone marrow mononuclear cells to recipient LEW following aortic grafting. Fucan, a low molecular weight sulfated polysaccharide (LMWF) was used to mobilize bone marrow-derived progenitor cells. Five groups of 10 rats included: untreated isografts (BN to BN), untreated allografts, and three allografted groups, respectively, treated by fucan therapy, cell therapy, or cell and fucan therapy. Aorta were studied by morphometric analysis at 30 d. RESULTS: In the absence of treatment, intimal thickening was greater in allograft than in isograft groups (299±50 versus 3.5±1.7 µm, P<0.001). Cell therapy alone, fucan therapy alone, and the combined treatment were shown to prevent intimal thickening in allografts (5.1±1.7, 6.1±2.3, 4.1±2.5, versus 299±50 µm respectively, P<0.001). In the three treated groups, the intimal lining was a single layer of endothelial cells expressing CD34 positive, endothelial nitric oxide synthase (eNOS) positive, and Ox3 specific-recipient monoclonal antibody positive. CONCLUSION: These results provide the proof of concept of recipient syngenic bone-marrow cell therapy for the prevention of chronic vasculopathy.

Nephroangiosclerosis in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: is NOTCH3 mutation the common culprit?

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a systemic arterial disease characterized by impairment of vascular smooth muscle cell structure and function related to NOTCH3 mutations. Pathological findings include pathognomonic granular osmiophilic material (GOM) deposition with nonspecific hyalinization within the artery wall in a variety of tissues. The main clinical presentation is iterative strokes in young adults despite the lack of cardiovascular risk factors, leading to early dementia. Although arteriosclerosis and GOM have been found in kidneys from patients with CADASIL, kidney disease has been described only once up to now, in association with immunoglobulin A nephropathy. We report the case of a 61-year-old patient with a medical history of CADASIL and recent mild hypertension. His mother also showed neuropsychiatric symptoms and end-stage renal disease of unknown cause. The patient had a chronic kidney disease defined by means of estimated glomerular filtration rate using the 4-variable Modification of Diet in Renal Disease Study equation of 58 mL/min/1.73 m(2) associated with mild proteinuria and intermittent microscopic hematuria. Renal histological analysis showed severe arteriosclerosis and mild interstitial fibrosis. Glomeruli did not show mesangial immunoglobulin A deposition or focal segmental proliferation. Electron microscopic analysis showed typical GOM deposition in the vicinity of altered vascular smooth muscle cells in interlobular and juxtaglomerular arteries. The nephroangiosclerosis-like lesions were unusually severe in contrast to the recent mild hypertension. The presence of GOM strongly suggests that renal lesions were related to the NOTCH3 mutation. Here, we describe the first case of familial occurrence of kidney disease with decreased kidney function in the absence of coexisting nephropathy in patients with CADASIL. We discuss the role of NOTCH3 mutation in the pathogenesis of nephroangiosclerosis through functional impairment of renal microcirculation or primary Notch3-related vascular disease.

Low molecular weight fucoidan prevents neointimal hyperplasia after aortic allografting.

BACKGROUND: Fucoidan, a new low molecular weight sulfated polysaccharide (LMWF), has previously been shown to mobilize bone marrow-derived progenitors cells via stimulation of stromal derived factor (SDF)-1 release. Mobilized progenitor cells have been suggested to repair intimal lesions after immune-mediated endothelial injury and thus prevent intimal proliferation. The aim of this study was to evaluate the effect of LMWF treatment in a rat aortic allograft model of transplant arteriosclerosis (TA). METHODS: Aortic grafts were performed in Brown Norway (BN, donor) and Lewis (Lew, recipient) rats. The recipient rats were treated with LMWF (5 mg/kg/day) and sacrificed at 30 days. To determine the role of SDF-1 in mediating the effects of LMWF, a specific inhibitor of the SDF-1 receptor CXCR4, AMD 3100 (20 microg/kg/day), was used. The grafted segments were evaluated by morphometric (histochemical) analyses. RESULTS: Untreated aortic allografts exhibited severe intimal proliferation, indicative of TA. In contrast, LMWF treatment significantly prevented allograft intimal proliferation as compared with controls (5.7+/-3 vs. 66.2+/-6 microm, P<0.01) and permitted a normalization of the intima/media ratio (0.1+/-0.1 vs. 1.7+/-0.3, P<0.01). Further, LMWF treatment stimulated allograft reendothelialization, as evidenced by strong intimal endothelial nitric oxide synthase antibody and CD31 signals. Unexpectedly, AMD treatment failed to prevent the protective effect of LMWF on intimal thickening and AMD treatment alone was found to reduced intimal proliferation in allografts. CONCLUSIONS: We found that LMWF treatment reduced intimal thickness and induced the presence of an endothelial cell lining in the vascular graft at 30 days. Our findings may suggest a novel therapeutic strategy in the prevention of TA.

Low molecular weight fucan prevents transplant coronaropathy in rat cardiac allograft model.

INTRODUCTION: Transplant arteriosclerosis is the main cause of long-term failure after cardiac transplantation. Vascular rejection is thought to be due to intimal proliferation occurring in response to arterial wall immune-mediated injury. A low molecular weight fucan (LMWF) compound, a sulfated polysaccharide, has been demonstrated to increase plasma levels of stromal cell-derived factor 1 (SDF-1) and consequently to mobilize bone marrow-derived vascular progenitor cells (BMVPC). The aim of this study was to evaluate the capacity of LMWF to prevent coronary intimal proliferation in a rat cardiac allograft model. METHODS: Heterotopic abdominal cardiac graftings were performed in Brown Norway (BN) and Lewis (LEW) rats. Animals were divided into 4 groups of 10 rats. Two groups were treated intramuscularly with LMWF (5 mg/kg/day) (one BN to BN isograft group, and one BN to LEW allograft group); and two control groups were LMWF-untreated (one BN to BN isograft group and one BN to LEW allograft group). All animals were treated by cyclosporin (15 mg/kg/day) sub-cutaneously and sacrificed at day 30. The cardiac grafts were assessed by morphometry of structural parameters and by histological and immunohistochemical analyses. RESULTS: All cardiac isografts were devoid of any coronary and parenchymal lesions. In contrast, the majority of untreated allografts developed coronary intimal proliferation in close association with intimal and adventitial inflammatory CD68(+) cell infiltration. Further, the parenchyma exhibited large areas of actin(+) cells (myofibroblasts) of recipient origin colocalized with the CD68(+) infiltrating cells. Interestingly, all LMWF-treated allografts were well protected against coronary and parenchymal lesions and the coronary arteries exhibited an intimal monolayer of flat cells, which however were CD34 negative. CONCLUSION: treatment with LMWF appeared very effective in this rat cardiac allograft model to prevent arterial and parenchymal lesions occurring in response to alloimmune injury. However this protective effect does not appear to depend on mobilization of bone marrow-derived cells.

Clinical Value of Natriuretic Peptides in Predicting Time to Dialysis in Stage 4 and 5 Chronic Kidney Disease Patients.

BACKGROUND: Anticipating the time to renal replacement therapy (RRT) in chronic kidney disease (CKD) patients is an important but challenging issue. Natriuretic peptides are biomarkers of ventricular dysfunction related to poor outcome in CKD. We comparatively investigated the value of B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) as prognostic markers for the risk of RRT in stage 4 and 5 CKD patients, and in foretelling all-cause mortality and major cardiovascular events within a 5-year follow-up period. METHODS: Baseline plasma BNP (Triage, Biosite) and NT-proBNP (Elecsys, Roche) were measured at inclusion. Forty-three patients were followed-up during 5 years. Kaplan-Meier analysis, with log-rank testing and hazard ratios (HR), were calculated to evaluate survival without RRT, cardiovascular events or mortality. The independent prognostic value of the biomarkers was estimated in separate Cox multivariate analysis, including estimated glomerular filtration rate (eGFR), creatininemia and comorbidities. RESULTS: During the first 12-month follow-up period, 16 patients started RRT. NT-proBNP concentration was higher in patients who reached endpoint (3221 ng/L vs 777 ng/L, p = 0.02). NT-proBNP concentration > 1345 ng/L proved significant predictive value on survival analysis for cardiovascular events (p = 0.04) and dialysis within 60 months follow-up (p = 0.008). BNP concentration > 140 ng/L was an independent predictor of RRT after 12 months follow-up (p<0.005), and of significant predictive value for initiation of dialysis within 60 months follow-up. CONCLUSIONS: Our results indicate a prognostic value for BNP and NT-proBNP in predicting RRT in stage 4 and 5 CKD patients, regarding both short- and long-term periods. NT-proBNP also proved a value in predicting cardiovascular events. Natriuretic peptides could be useful predictive biomarkers for therapeutic guidance in CKD.

A kinetic study of SDF-1, VEGF and MCP-1 blood and tissue levels after aortic transplantation in mice.

Vascular rejection is characterized by intimal proliferation and perivascular inflammation. We hypothesize that recipient stem cell therapy could prevent or ameliorate the development of the obliterative lesion. We studied the kinetic expression of three cytokines (SDF-1, MCP-1, VEGF) implicated in mobilization, homing and differentiation of progenitor cells during vascular aggression. An aortic allograft mouse model was used (BALBc donor-C57BL6/j recipient). Ten mice were sacrificed at Day 0, D1, D3, D6, D9, D12, and D20. Cytokine rates were measured in blood and in graft tissue by an ELISA technique. Results showed that in the allograft, SDF-1 and VEGF tissue levels were significantly increased at D12 as compared to the isograft (SDF-1: 22.16 ng/mg vs. 5.69 ng/mg, t=3.38; VEGF: 28.3 pg/mg vs. 9.3 pg/mg, t=3.06). In allografted and isografted groups, MCP-1 tissue levels were higher at D0 as compared to the other time points, without any difference between the two groups. These results prompt us to consider cell therapy at D0 and D12 in this mouse model of aortic graft.

Protective effect of mycophenolate mofetil on endothelial function in an aortic allograft model.

BACKGROUND: Whether mycophenolate mofetil (MMF) can prevent the vascular endothelial dysfunction related to the administration of calcineurin inhibitor after organ transplantation remains unknown. METHODS: Four groups of Lewis rats, grafted with Brown Norway donor aortic abdominal allograft, received since the transplantation cyclosporine A (CsA, 5 mg/kg/day), MMF (40 mg/kg/day), CsA+MMF, or vehicle (control) for 2 weeks. RESULTS: Fifteen days after transplantation, all immunosuppressive regimens were equally effective in preventing graft rejection. When compared with control rats, the endothelium-dependent relaxation to acetylcholine was reduced, and the vasoconstrictor effect of phenylephrine was enhanced in thoracic aorta of CsA-treated rats but not in rats treated with MMF alone or combined with CsA without difference for the endothelium-independent relaxation to sodium nitroprusside. The relaxation to acetylcholine was abolished by the nitric oxide (NO)-synthase inhibitor N-nitro-l-arginine in all groups. Moreover, the endothelial NO-synthase protein dimer:monomer ratio in the thoracic aorta and the plasma nitrites concentrations, an indicator of NO availability, were decreased in CsA-treated rats but not in rats treated with MMF alone or combined with CsA. CONCLUSIONS: This study demonstrates that MMF prevents systemic endothelial dysfunction and the enhanced sensitivity to vasoconstrictors related to CsA administration in a rat allograft aortic model through an increase in NO availability related to the improvement of endothelial NO-synthase functionality.

Antidonor humoral transfer induces transplant arteriosclerosis in aortic and cardiac graft models in rats.

OBJECTIVE: The humoral pathway is suggested as playing a key role in transplant arteriosclerosis. The humoral immunity is demonstrated in the present study to induce direct vascular lesion. METHODS: Ten abdominal aortic grafts were performed on 4 groups of rats: Brown Norway (BN) isografts, BN to Lewis (LEW) allografts, and two BN to nude (RNU) grafted groups with and without any humoral transfer. The humoral sera were obtained by skin grafts performed in BN to LEW combination. Lewis anti-BN alloantisera was transferred in nude recipients through intraperitoneal injections. The aortic wall was histologically studied with morphometric analysis on the 21st day. Two additional BN to RNU aortic graft groups were evaluated by immunohistochemistry on days 3 (10 rats) and 10 (10 rats). RESULTS: In the absence of the humoral transfer, the BN aortic wall implanted in RNU remained intact. The humoral transfer induced a marked intimal proliferation (63 +/- 4 vs 4 +/- 1.1 microm; P < .001) and an adventitial cell infiltration (5.1 +/- 0.7 vs 2.8 +/- 0.6 x 10(3) c/mm2, P < .001). The medial thickness and the medial cell density were not modified. On day 3, the remaining endothelial cells were covered by immunoglobulin G deposits. On day 10 the endothelial cells disappeared completely and intimal proliferation occurred. In an additional cardiac graft group, transplant coronary arteriopathy was evidenced in 7 of the 9 nude recipients that had undergone the humoral transfer. CONCLUSION: The transplant arterial occlusive lesion is demonstrated here (1) to be induced by humoral antidonor immunity and (2) to be linked to an adventitial or perivascular inflammation.