Miquel Blasco

Tratamiento eficaz de la arteriolopatía urémica calcificante con bifosfonatos

BACKGROUND AND OBJECTIVES Calcific uraemic arteriolopathy (CUA), also known as calciphylaxis, is a rare but life-threatening condition that almost exclusively affects patients with chronic kidney disease. Several therapies have been employed to treat this disease but with irregular results. We report a prospective case series of eight patients diagnosed with CUA in our unit between 2002 and 2010. MATERIAL AND METHOD The series consisted of eight patients with CUA (including 4 men, 5 dialysis patients and 3 with functioning allografts) who were treated with bisphosphonates. The diagnosis was by clinical suspicion and a confirmatory biopsy. Five patients had a previous history of high calcium-phosphorus product, 6 had a history of high parathyroid hormone levels (>800pg/ml), 4 had undergone parathyroidectomy, 5 had a history of high cumulative doses of steroids, and 6 patients were under dicoumarin treatment. None of the patients were obese or had diabetes mellitus. RESULTS In all patients, progression of skin lesions stopped between 2 to 4 weeks after starting bisphosphonate therapy, with no changes in blood levels of calcium and phosphate. Improvement in pain and lesions was faster in patients receiving intravenous ibandronate. All of these patients remained on bisphosphonate treatment for at least 6 months until the wounds healed completely. No recurrences have been observed after follow-up periods between 1 and 9 years. Renal function remained stable in transplant recipients. The treatment was well tolerated and no adverse effects were observed. CONCLUSIONS Bisphosphonates could be a new and attractive alternative to treat CUA.

Antiphospholipase A2 Receptor Antibody Levels Predict the Risk of Posttransplantation Recurrence of Membranous Nephropathy.

Background Secretory phospholipase A2 receptor (PLA2R) is the target antigen of the auto-antibodies produced in most (∼70%) patients with primary membranous nephropathy (pMN). The applicability of anti-PLA2R1 antibody monitoring for the prediction of MN recurrence in kidney transplant recipients still is a matter of debate. Methods We sought to characterize the presence and concentration of anti-PLA2R antibodies by enzyme-linked immunosorbent assay (ELISA) in a cohort of 21 patients with pMN before and after transplantation to evaluate whether anti-PLA2R concentrations could predict pMN recurrence. Results The presence of pMN recurrence was significantly correlated with the existence of a positive ELISA assay at graft biopsy or with high level of anti-PLA2R1 activity before transplantation (P = 0.03). In the receiver operating characteristic analysis, anti-PLA2R levels (cut-off of 45 U/mL) during the pretransplantation period accurately predicted pMN recurrence, with a sensitivity of 85.3%, specificity of 85.1%, negative predictive value of 92%, and an area under the curve of 90.8%. This finding supports the hypothesis that anti-PLA2R cause pMN recurrence in humans and indicates the need to prove in an experimental model. Furthermore, 6 of 7 patients with recurrence were carriers of HLA DQA1* 05:01/05 and DQB1* 02:01, confirming these DQ alleles as those associated with higher anti-PLA2R levels. Conclusions This study is the first to demonstrate pretransplantation circulating anti-PLA2R antibodies in a cohort of renal transplant recipients who prospectively developed recurrent disease. Currently, anti-PLA2R levels measured by ELISA may be a rational tool to establish the risk of MN recurrence in renal allograft recipients.

Rescue therapy with eculizumab in a transplant recipient with atypical haemolytic-uraemic syndrome

Haemolytic–uraemic syndrome is a clinical syndrome characterized by thrombocytopaenia, non-autoimmune haemolytic anaemia and renal impairment. Pathological alterations in kidney samples show thrombotic microangiopathy. The underlying pathogenesis is endothelial cell injury with thrombotic occlusion of the arterioles and capillaries. A variety of causes have been identified, associated with infection of Escherichia coli O157:H7, environmental factors as immunosuppressive drugs and genetic deficiencies in complement regulatory factors. The latter is called atypical haemolytic–uraemic syndrome (aHUS). Here, we present a patient with severe aHUS with complement factor H deficiency triggered by cocaine use and recurrence after kidney transplantation. The patient restarted haemodialysis for severe renal insufficiency and anti-C5 antibody eculizumab was used as salvage treatment with progressive recovery of graft function and suppression of dialysis.

Elevated factor H–related protein 1 and factor H pathogenic variants decrease complement regulation in IgA nephropathy

IgA nephropathy (IgAN), a frequent cause of chronic kidney disease worldwide, is characterized by mesangial deposition of galactose-deficient IgA1-containing immune complexes. Complement involvement in IgAN pathogenesis is suggested by the glomerular deposition of complement components and the strong protection from IgAN development conferred by the deletion of the CFHR3 and CFHR1 genes (ΔCFHR3-CFHR1). Here we searched for correlations between clinical progression and levels of factor H (FH) and FH-related protein 1 (FHR-1) using well-characterized patient cohorts consisting of 112 patients with IgAN, 46 with non-complement-related autosomal dominant polycystic kidney disease (ADPKD), and 76 control individuals. Patients with either IgAN or ADPKD presented normal FH but abnormally elevated FHR-1 levels and FHR-1/FH ratios compared to control individuals. Highest FHR-1 levels and FHR-1/FH ratios are found in patients with IgAN with disease progression and in patients with ADPKD who have reached chronic kidney disease, suggesting that renal function impairment elevates the FHR-1/FH ratio, which may increase FHR-1/FH competition for activated C3 fragments. Interestingly, ΔCFHR3-CFHR1 homozygotes are protected from IgAN, but not from ADPKD, and we found five IgAN patients with low FH carrying CFH or CFI pathogenic variants. These data support a decreased FH activity in IgAN due to increased FHR-1/FH competition or pathogenic CFH variants. They also suggest that alternative pathway complement activation in patients with IgAN, initially triggered by galactose-deficient IgA1-containing immune complexes, may exacerbate in a vicious circle as renal function deterioration increase FHR-1 levels. Thus, a role of FHR-1 in IgAN pathogenesis is to compete with complement regulation by FH.

Eculizumab in pregnancy-associated atypical hemolytic uremic syndrome: insights for optimizing management

Pregnancy-associated atypical hemolytic uremic syndrome is a systemic disease associated with high morbidity and mortality rates, caused by dysregulation of the alternative complement pathway, leading to uncontrolled complement activation resulting in thrombotic microangiopathy. This condition can be effectively treated by anti-C5 therapy, which controls complement activation. Treatment can be safely discontinued after complete remission and resolution of the precipitating cause, especially in patients with a low-risk genetic profile.

Molecular Basis of Factor H R1210C Association with Ocular and Renal Diseases

The complement factor H (FH) mutation R1210C, which was described in association with atypical hemolytic uremic syndrome (aHUS), also confers high risk of age-related macular degeneration (AMD) and associates with C3 glomerulopathy (C3G). To reveal the molecular basis of these associations and to provide insight into what determines the disease phenotype in FH-R1210C carriers, we identified FH-R1210C carriers in our aHUS, C3G, and AMD cohorts. Disease status, determined in patients and relatives, revealed an absence of AMD phenotypes in the aHUS cohort and, vice versa, a lack of renal disease in the AMD cohort. These findings were consistent with differences in the R1210C-independent overall risk for aHUS and AMD between mutation carriers developing one pathology or the other. R1210C is an unusual mutation that generates covalent complexes between FH and HSA. Using purified FH proteins and surface plasmon resonance analyses, we demonstrated that formation of these FH-HSA complexes impairs accessibility to all FH functional domains. These data suggest that R1210C is a unique C-terminal FH mutation that behaves as a partial FH deficiency, predisposing individuals to diverse pathologies with distinct underlying pathogenic mechanisms; the final disease outcome is then determined by R1210C-independent genetic risk factors.

Mid-Dilution Hemodiafiltration: A Comparison with Pre- and Postdilution Modes Using the Same Polyphenylene Membrane

As a change from Diapes to polyphenylene membrane in the mid-dilution filter has recently been developed, the aim of this study was to compare mid-dilution using this new dialyzer versus pre- and postdilution. The prospective study included 20 patients who underwent 4 hemodiafiltration (HDF) sessions: 1.7 m2 polyphenylene and predilution infusion flow (Qi) 200 ml/min, 1.7 m2 and postdilution Qi 100 ml/min, 1.9 and 2.2 m2 mid-dilution both with Qi 200 ml/ min. The urea and creatinine reduction ratios were slightly higher in postdilution. The β2-microglobulin (85.8%), myoglobin (73.6%), prolactin (67.8%) and retinol-binding protein (29.2%) reduction ratios with 1.9 m2 mid-dilution, which was similar to 2.2 m2 mid-dilution, were significantly higher than with the post- and predilution modes. Mid-dilution appears to be a good HDF alternative that allows a better removal of larger molecules than postdilution and, mainly, predilution. Mid-dilution using 1.9 or 2.2 m2 dialyzers, at the same convective volume, showed a similar removal.

Eculizumab in secondary atypical haemolytic uraemic syndrome

Background. Complement dysregulation occurs in thrombotic microangiopathies (TMAs) other than primary atypical haemolytic uraemic syndrome (aHUS). A few of these patients have been reported previously to be successfully treated with eculizumab. Methods. We identified 29 patients with so‐called secondary aHUS who had received eculizumab at 11 Spanish nephrology centres. Primary outcome was TMA resolution, defined by a normalization of platelet count (>150 × 109/L) and haemoglobin, disappearance of all the markers of microangiopathic haemolytic anaemia (MAHA), and improvement of renal function, with a ≥25% reduction of serum creatinine from the onset of eculizumab administration. Results. Twenty‐nine patients with secondary aHUS (15 drug‐induced, 8 associated with systemic diseases, 2 with postpartum, 2 with cancer‐related, 1 associated with acute humoral rejection and 1 with intestinal lymphangiectasia) were included in this study. The reason to initiate eculizumab treatment was worsening of renal function and persistence of TMA despite treatment of the TMA cause and plasmapheresis. All patients showed severe MAHA and renal function impairment (14 requiring dialysis) prior to eculizumab treatment and 11 presented severe extrarenal manifestations. A rapid resolution of the TMA was observed in 20 patients (68%), 15 of them showing a ≥50% serum creatinine reduction at the last follow‐up. Comprehensive genetic and molecular studies in 22 patients identified complement pathogenic variants in only 2 patients. With these two exceptions, eculizumab was discontinued, after a median of 8 weeks of treatment, without the occurrence of aHUS relapses. Conclusion. Short treatment with eculizumab can result in a rapid improvement of patients with secondary aHUS in whom TMA has persisted and renal function worsened despite treatment of the TMA‐inducing condition.

Influence of renal replacement therapy on immune response after one and two doses of the A(H1N1) pdm09 vaccine

Please cite this paper as: Quintana et al. (2012) Influence of renal replacement therapy on immune response after one and two doses of the A(H1N1) pdm09 vaccine. Influenza and Other Respiratory Viruses DOI: 10.1111/irv.12024.

Practical Utility of On-Line Clearance and Blood Temperature Monitors as Noninvasive Techniques to Measure Hemodialysis Blood Access Flow

Background/Aims: Access blood flow (Qa) measurements are recommended by the current guidelines as one of the most important components in vascular access maintenance programs. This study evaluates the efficiency of Qa measurement with on-line conductivity (OLC-Qa) and blood temperature monitoring (BTM-Qa) in comparison with the gold standard saline dilution method (SDM-Qa). Subjects and Methods: 50 long-term hemodialysis patients (42 arteriovenous fistulas/8 arteriovenous grafts) were studied. Bland-Altman and Lin’s coefficient (ρc) were used to study accuracy and precision. Results: Mean values were 1,021.7 ± 502.4 ml/min SDM-Qa, 832.8 ± 574.3 ml/min OLC-Qa (p = 0.007) and 1,094.9 ± 491.9 ml/min with BTM-Qa (p = NS). Biases and ρc obtained were –188.8 ml/min (ρc 0.58) OLC-Qa and 73.2 ml/min (ρc 0.89) BTM-Qa. The limits of agreement (bias ± 1.96 SD) obtained were from –1,119 to 741.3 ml/min (OLC-Qa) and –350.6 to 497.2 ml/min (BTM-Qa). Conclusions: BTM-Qa and OLC-Qa are valid noninvasive and practical methods to estimate Qa, although BTM-Qa was more accurate and had better concordance than OLC-Qa compared with SDM-Qa.