Temporal IgG Subtype Changes in Recurrent Idiopathic Membranous Nephropathy.

Determination of the IgG subtypes within the immune deposits in membranous nephropathy (MN) may be helpful in the differential diagnosis. IgG4 is the predominant subtype in idiopathic MN and recurrent MN, while IgG1, IgG2, and IgG3 subtypes are more common in secondary MN and de novo disease in the allograft. The temporal change of IgG subclasses in individual patients and its correlation with clinical variables have not been studied. We reviewed all posttransplantation protocol and indication biopsies (49) in 18 patients with recurrent MN who underwent transplantation at our center between 1998 and 2013 and performed IgG subtyping (IgG1-4). We tested serum for M-type phospholipase A2 receptor (PLA2 R) autoantibodies or performed PLA2 R antigen staining on the kidney biopsy. IgG4 was the (co)dominant IgG subtype in 10 of 14 biopsies at the diagnosis of recurrence regardless of PLA2 R association. In 8 of 12 transplantations with serial biopsies, the (co)dominant subtype did not change over time. There was a trend toward IgG1 and IgG3 (co)dominance in biopsies >1 year from recurrence and more IgG1 (co)dominant subtyping in the setting of more-advanced EM deposits. Treatment with rituximab did not affect the IgG subtype. In conclusion, the dominant IgG subtype did not change over time in recurrent MN.

Autolytic degradation of ocriplasmin: a complex mechanism unraveled by mutational analysis.

Ocriplasmin, a truncated form of plasmin, is commercialized in the USA and in Europe under the trade name Jetrea(®), and indicated for the treatment of symptomatic vitreomacular adhesion and vitreomacular traction including when associated with macular hole ≤400 µm, respectively. We have shown in a previous study that ocriplasmin undergoes autolytic degradation when injected in eye vitreous, which leads to its rapid inactivation. In order to investigate this process further, we have introduced in ocriplasmin a variety of amino acid substitutions within or in the immediate vicinity of the three major autolytic cleavage sites. We demonstrate here that autolytic inactivation of ocriplasmin is a sequential process where initial cleavage occurs primarily between residues 156 and 157. Reduction or even blocking of autolysis can be achieved by mutating a limited number of key residues. In this study, we also report the identification of a series of ocriplasmin variants with improved resistance to autolysis and unimpaired catalytic activity. Such variants represent useful tools for the exploration of therapeutic approaches aiming at non-surgical resolution of vitreomacular adhesion.

The pharmacokinetics and pharmacodynamics of vancomycin in clinical practice: evidence and uncertainties.

Vancomycin has been used extensively since the late 1950s. Despite the introduction of several new valuable anti-Gram-positive antibiotics during recent years and the waning susceptibility of staphylococci to vancomycin, it remains the gold standard for the treatment of bacteraemia caused by methicillin-resistant staphylococci. Vancomycin has clear dose-response and dose-toxicity correlations. It is widely accepted that these correlations are best predicted by the AUC/MIC model, with target levels of >400 being the clinical cut-off. The experimental base of this model is less robust than frequently believed, and several important issues in vancomycin resistance, such as biofilm resistance and the inoculum effect, are not included. Based on this model, current dosing guidelines propose intermittent dosing of vancomycin with target trough levels of 15-20 mg/L. Dose adaptations according to renal function have been proposed but are not yet validated. Clinical data also support the use of continuous infusion with target plateau levels of 20-25 mg/L, with similar efficacy at the cost of lower nephrotoxicity. Despite decades of intense clinical use and numerous studies and publications, the optimal dosing strategy for vancomycin reconciling the high needs of the dose-response relationship with the serious drawbacks of the dose-toxicity relationship remains to be established.

Fluctuations of haemoglobinaemia in chronic haemodialysis patients.

In March 2008 and June 2009, an ad hoc working group of nephrologists discussed the status of anaemia therapy with erythropoiesis-stimulating agents [ESA] in patients on chronic haemodialysis, the phenomenon of fluctuations of haemoglobinaemia, and the need for individualisation of ESA treatment. The working group put together the following statements: (1) ESAs increase the haemoglobin concentration and adaptations of the ESA dose adjust the response according to a negative-feedback loop. The long lag time between an ESA dose change and its effect on erythropoiesis is cumbersome. The optimal haemoglobin target concentration is different for every haemodialysis patient; the lowest haemoglobin concentration upon which one could consistently demonstrate a positive subjective and objective clinical benefit in chronic dialysis is 11 g/dL, in contrast to the lowest haemoglobin concentration of 10 g/dL recommended in the current EMEA label for ESAs. (2) Intra-individual fluctuation of haemoglobinaemia over time is unavoidable, not only due to the ESA dose/haemoglobin response interaction, but also, and more importantly, due to the occurrence of acute illnesses and exacerbations of co-morbid conditions. Many different methodologies to characterise haemoglobin variability have been described but there is currently no universally applied definition of the phenomenon. (3) An impact of the haemoglobin level and the amplitude of the haemoglobin fluctuations on patient outcome has been observed. Without disclosing any causal relationship, worse outcomes were associated with haemoglobin fluctuations around the lower target level, but later on, more simply linked to the relative time spent below the haemoglobin concentration of 11 g/dL and to the administration of inappropriately high ESA doses in order to achieve the recommended haemoglobin target range. A plausible mechanism might be that acute illnesses blunt the patients' basal ESA sensitivity; this leads to subnormal and/or varying haemoglobin levels, currently initiating an ESA dose increase. The longer it takes the patient to recover from the acute illness, the more the prolongation of the clinically poor condition is to some extent maintained by the persistence of low haemoglobinaemia and/or by the administration of high ESA doses, and, as such, on their turn possibly contributing to an ultimate poor outcome. In the absence of clinical trials, recommendations should be offered how to proceed with the administration of ESAs as optimal as possible in periods of clinical instability.

Successful treatment of renal AA amyloidosis in familial Mediterranean fever with pegylated alpha-2a interferon.

Renal AA amyloidosis is a severe consequence of chronic inflammatory diseases such as familial Mediterranean fever (FMF). FMF is caused by mutations in the MEFV gene, resulting in defective control of granulocyte-mediated inflammation. Interferon-alpha is known to induce MEFV expression in monocytes and granulocytes in vitro. We present the first case of colchicine-resistant FMF in which a durable disease remission and regression of renal amyloidosis was induced by chronic treatment with pegylated interferon-alpha.

Autologous transplantation of bone marrow mononuclear cells for limb ischemia in a caucasian population with atherosclerosis obliterans.

BACKGROUND: Autologous transplantation of bone marrow mononuclear cells (ATBMMNC) has been used successfully in critical limb ischemia. All reported patients were of Asian descent, however, and several studies included only young patients with thromboangiitis obliterans. Whether the beneficial results can be extrapolated to older Caucasian patients with atherosclerosis obliterans and a heavy burden of cardiovascular risk factors remains unclear. METHODS: We enrolled 16 patients (age 78 +/- 2 year) with critical limb ischemia and a high prevalence of hypertension, smoking, diabetes, hypercholesterolemia and uremia. Mononuclear cells were isolated from the bone marrow and injected in the gastrocnemius muscle of the affected limb. RESULTS: Four patients died because of progressive gangrene (two) or unrelated causes (two). Three patients required an amputation and one patient a femorocrural bypass within 12 weeks. The remaining eight patients had a modest improvement of resting pain and/or trophic lesions. Transcutaneous oxygen pressure (ratio lesion/reference) improved from 0.51 +/- 0.11 before to 0.86 +/- 0.03 (P < 0.001) after 12 weeks, whereas ankle-brachial index did not change significantly (0.42 +/- 0.15 vs. 0.59 +/- 0.1; P = 0.23). The number of visible collateral vessels on digital subtraction angiography changed with 0.89 +/- 0.86 on a scale of 1-4 (P = 0.33). Capillary surface area in a biopsy of gastrocnemius, evaluated by immunostaining for endothelial nitric oxide synthase, increased from 0.61 +/- 0.07% to 2.38 +/- 0.73% (P < 0.05). CONCLUSIONS: Although ATBMMNC was associated with objective signs of neovascularization, symptomatic improvement was only modest and restricted to the least affected patients. The discrepancy with previous findings may be related to the high prevalence of cardiovascular risk factors which causes endothelial progenitor cell dysfunction.

Novel insights in the treatment of diabetic nephropathy.

Diabetes is currently one of the leading causes of end-stage renal failure requiring renal replacement therapy in the Western World. About 15% to 20% of type 1 diabetic patients and 30% to 40% of type 2 diabetic patients will eventually develop end-stage renal failure. To prevent the development or progression of diabetic kidney disease, good glycaemic control remains the cornerstone in the management of diabetic patients. Beyond glycaemic control, other metabolic factors have been shown to be involved in the development of diabetic kidney disease, i.e. advanced glycation endproducts (AGEs) and the aldose reductase pathway. Furthermore, an adequate control of high blood pressure and treatment of microalbuminuria are major therapeutic targes. To achieve adequate blood pressure control, a combination therapy with different classes of antihypertensive agents is often necessary, especially including angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Other vasoactive factors involved in diabetic nephropathy such as endothelin and nitric oxide will be covered briefly. Besides hyperglycaemia and high blood pressure, other risk factors have been identified in the development or progression of diabetic kidney disease: smoking, hyperlipidaemia, obesity and high protein intake. Their impact on renal function will be highlighted. Finally, recent research has also identified intracellular pathways such as the diacylglycerol-protein kinase C pathway and several growth factors, such as growth hormone, insulin-like growth factor, transforming growth factor-beta, vascular endothelial growth factor, and platelet derived growth factor as players in diabetic kidney disease.

The lectin-like domain of thrombomodulin interferes with complement activation and protects against arthritis.

BACKGROUND: Thrombomodulin (TM) is predominantly a vascular endothelial cell plasma membrane glycoprotein that, via distinct structural domains, interacts with multiple ligands, thereby modulating coagulation, fibrinolysis, complement activation, inflammation and cell proliferation. We previously reported that by mediating signals that interfere with mitogen-activated protein kinase and nuclear factor kappaB pathways, the amino-terminal C-type lectin-like domain of TM has direct anti-inflammatory properties. METHODS: In the current study, we use murine models of acute inflammatory arthritis and biochemical approaches to assess the mechanism by which the lectin-like domain of TM modifies disease progression. RESULTS: Mice lacking the lectin-like domain of TM (TM(LeD/LeD)mice) develop inflammatory arthritis that is more rapid in onset and more severe than that developed in their wildtype counterparts. In two models of arthritis, treatment of mice with recombinant soluble lectin-like domain of TM significantly suppresses clinical evidence of disease and diminishes monocyte/macrophage infiltration into the synovium, with weaker expression of the pro-inflammatory high mobility group box chromosomal protein 1. While thrombin-TM mediated activation of thrombin activatable fibrinolysis inhibitor inactivates complement factors C3a and C5a, we show that TM has a second independent mechanism to regulate complement: the lectin-like domain of TM directly interferes with complement activation via the classical and lectin pathways. CONCLUSIONS: These data extend previous insights into the mechanisms by which TM modulates innate immunity, and highlight its potential as a therapeutic target for inflammatory diseases.

Management of therapy-resistant systemic lupus erythematosus with rituximab: report of a case and review of the literature.

Therapy of systemic lupus erythematosus (SLE) with major organ involvement consists of aggressive immunosuppression with glucocorticoids and cytotoxic agents. When remission is achieved, maintenance therapy is begun to reduce the risk of relapse while minimizing toxicity. Remission with standard therapy is, however, not always achieved. We discribe a women with SLE and microangiopathic haemolytic anaemia and thrombocytopenia, pneumonitis and nephritis refractory to high-dose steroids, pulse cyclophosphamide, plasmapheresis and intravenous immunoglobulins. The anti-CD20 monoclonal antibody rituximab was administered, resulting in major clinical and biochemical improvement. Therapy-resistant SLE generally has an ominous prognosis. A few anecdotal reports and small open studies describe beneficial effects of rituximab in these cases. Rituximab may be a promising new approach to improve the dismal outcome of therapy-resistant SLE.

Inhibition of vascular endothelial growth factor (VEGF) does not affect early renal changes in a rat model of lean type 2 diabetes.

Type 2 diabetes is the most frequent cause of end-stage renal failure in many Western countries. Approximately 10-15 % of all type 2 diabetics are lean. Various growth factors and cytokines have been implicated in the pathophysiology of diabetic kidney disease, including vascular endothelial growth factor (VEGF). To elucidate a role for VEGF in the renal changes associated with type 2 diabetes, we examined the effect of a VEGF-antibody (ab) on early renal changes in the Goto-Kakizaki (GK) rat, a lean type 2 diabetes model. GK-rats were treated for 6 weeks with the VEGF-ab or with an isotype-matched irrelevant IgG. Wistar rats were used as non-diabetic controls. Placebo-treated GK-rats showed a pronounced increase in glomerular volume and urinary albumin excretion (UAE) and no change in the renal expression of endothelial nitric oxide synthase (eNOS) compared to placebo-treated non-diabetic controls. Kidney weight and creatinine clearance were no different between the groups. VEGF-ab treatment had no effect on glomerular volume, UAE, eNOS expression, body weight, blood glucose levels or food intake, but lowered serum insulin levels in non-diabetic and diabetic animals. We conclude that VEGF inhibition has minimal effects on early renal changes in GK-rats.

A case of secondary frosted branch angiitis in Behçet's disease.

We report a case of Behcet's disease in a pregnant woman associated with secondary Frosted Branch Angiitis (FBA). FBA is a rare entity characterized by a florid translucent retinal perivascular sheathing of both arterioles and venules, with variable uveitis, retinal oedema and visual loss. To our knowledge, this is the first published report of FBA secondary to Behcet's disease in pregnancy.

The role of hyperhomocysteinemia in nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation.

Hyperhomocysteinemia (HHcy) is associated with impaired endothelial-dependent vasodilatation and increased risk of atherosclerosis and thrombosis. Here, we summarize some of our previous work on the effect of HHcy on pathways involved in endothelium-dependent vasodilatation, and present new data concerning the endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation. We showed that the 894 G>T single-nucleotide polymorphism in the human endothelial nitric oxide synthase gene (eNOS) increased the risk of recurrent venous thrombosis in individuals with elevated homocysteine levels, indicating that the pathophysiological mechanism in HHcy involves impaired NO-mediated vasodilatation. In addition, the EDHF-mediated vasodilatation of the renal artery was disturbed in diet-induced hyperhomocysteinemic rats. Interestingly, we demonstrated that pretreatment of rats with periodate-oxidized adenosine (Adox), which is an inhibitor of S-adenosylhomocysteine hydrolase, prevented the methionine-induced rise in plasma total Hcy (tHcy) levels but not the inhibition of the EDHF pathway. Furthermore, we demonstrated that S-adenosylhomocysteine (AdoHcy) and S-adenosylmethionine (AdoMet) levels were increased in the kidneys of diet-induced HHcy rats, resulting in a decreased AdoMet:AdoHcy ratio. In addition, we demonstrated that mRNA expression of Connexin 40, which is one of the structural subunits of gap-junctions, was down-regulated in endothelial cells of HHcy rats, and correlated with elevated AdoHcy levels in kidney of these rats. These finding suggest a key role for AdoHcy in relation to decreased Cx40 mRNA expression and impaired EDHF-mediated vasodilatation of HHcy rats.

Extensive acronecrosis as a manifestation of mixed cryoglobulinaemia: a case report.

Cryoglobulinaemia is a systemic disorder characterized by circulating antibodies that precipitate in the cold and resolve on rewarming. Three different types have been described, distinct in the class of immunoglobulins and their clonality. The clinical expression varies from purpura and arthralgia to progressive renal failure and even acronecrosis (1-3). Associated conditions are lymphoproliferative disorders, auto-immune diseases and chronic infections, but several cases occur in the absence of identifyable other disease states. The present communication reports on a case of mixed cryoglobulinaemia. Of particular interest are the rapidly progressive clinical evolution to acronecrosis of the four limbs, necessitating amputation, the presence of spurious leucocytosis and the absence of other systemic symptoms.

Intravital videomicroscopy in peritoneal dialysis research

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Early molecular events in the development of the diabetic cardiomyopathy.

UNLABELLED: Oxidative damage to DNA has been well documented in cardiac cells isolated from diabetic patients and rats with streptozotocin-induced diabetes mellitus (DM). This study evaluates possible molecular mechanisms for early events in the development of DM-induced cardiomyopathy. METHODS: To analyze the mechanism of overexpression of p21(WAF1/CIP1) and inhibition of cyclin D(1) expression in cardiomyocytes of diabetic rats we examined the methylation status of these genes by MS-PCR and assessed the possibility of epigenetic control of their expression. RESULTS: We found that the steady-state expression of both genes is influenced by their methylation status, as an epigenetic event, of their 5'-flanking regions upon development of diabetes. CONCLUSIONS: Oxidative damage contributes to the development of cardiomyopathy via p53-dependent activation of cardiac cell death. This pathway includes de novomethylation of the P53-inducible p21(WAF1/CIP1)-gene encoding a protein which binds to and inhibits a broad range of cyclin-cyclin-dependent kinase complexes.