Rational use of eculizumab in secondary atypical hemolytic uremic syndrome

Background

Secondary atypical hemolytic uremic syndrome (secondary aHUS) is a heterogeneous group of thrombotic microangiopathies (TMA) associated with various underlying conditions. Unlike primary aHUS, there is still no hard evidence on the efficacy of complement blockade in secondary aHUS, since the two main series that investigated this subject showed discrepant results. Our work aims to reassess the efficacy of eculizumab in treating secondary aHUS.

Methods

Observational, retrospective, single-center study, in which we analyzed the hematological and renal evolution of 23 patients diagnosed with secondary aHUS who received treatment with eculizumab and compared them with a control cohort of 14 patients. Complete renal response was defined as the recovery of renal function before the event, partial renal response as a recovery of 50% of lost glomerular filtration rate, and hematological response as normalization of hemoglobin and platelets.

Results

We found no statistically significant differences in baseline characteristics or disease severity between both groups. After a median of 5 doses of eculizumab, the group of patients who received complement blockade presented a significant difference in renal response (complete in 52.3% of patients and partial in 23.8%) compared to the control cohort (complete response 14.3% and partial of 14.3%). Rates of hematological remission were similar in both groups (90.9% in the eculizumab cohort and 85.7% in the control cohort).

Conclusion

Early and short-term use of eculizumab in patients with secondary aHUS could be an effective and safe therapeutic option, assuring better renal recovery compared to patients who do not receive complement blockade.

Complement alternative pathway determines disease susceptibility and severity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis

Activation of the alternative pathway (AP) of complement is involved in the pathogenesis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), although the underlying molecular mechanisms are unclear. To gain insight into the role of the AP, common gene variants in CFH/CFHR1-5, CFB, C3 and MCP, and longitudinal determinations of plasma C3, C4, FH, FHR-1, FHR-2, FHR-5, FB, properdin and sC5b-9 levels were analyzed in a Spanish AAV cohort consisting of 102 patients; 54 with active AAV (active cohort) and 48 in remission not receiving immunosuppressants or dialysis therapy (remission cohort). The validation cohort consisted of 100 patients with ANCA-associated glomerulonephritis. Here, we demonstrated that common genetic variants in complement components of the AP are associated with disease susceptibility (CFB32Q/W) or severity of kidney damage in AAV (CFH-H1, CFH1H2 and ΔCFHR3/1). Plasma levels of complement components were significantly different between active and remission cohorts. In longitudinal observations, a high degree of AP activation at diagnosis was associated with worse disease outcome, while high basal FHR-1 levels and lower FH/FHR-1 ratios determined severe forms of kidney associated AAV. These genetic and plasmatic findings were confirmed in the validation cohort. Additionally, autoantibodies against FH and C3 convertase were identified in one and five active patients, respectively. Thus, our study identified key genetic and plasma components of the AP that determine disease susceptibility, prognosis, and severity in AAV. Our data also suggests that balance between FH and FHR-1 is critical and supports FHR-1 as a novel AP-specific therapeutic target in AAV.

Efficacy and Safety of Iptacopan in Patients With C3 Glomerulopathy

Introduction

Complement 3 glomerulopathy (C3G) is a rare inflammatory kidney disease mediated by dysregulation of the alternative complement pathway. No targeted therapy exists for this aggressive glomerulonephritis. Efficacy, safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) (measured by complement biomarkers) of iptacopan were assessed in patients with C3G.

Methods

In this phase 2, multicenter, open-label, single-arm, nonrandomized study, adults with biopsy-proven, native kidney C3G (native cohort) and kidney transplant recipients with C3G recurrence (recurrent kidney transplant [KT] cohort) received iptacopan twice daily (bid) for 84 days (days 1-21: 10-100 mg; days 22-84: 200 mg). The primary end point was the urine protein-to-creatinine ratio (UPCR; native cohort) and the change in the C3 deposit score of kidney biopsy (recurrent KT cohort). The complement pathway measures included Wieslab assay, soluble C5b9, and serum C3 levels.

Results

A total of 27 patients (16 native cohort and 11 recurrent KT cohort) were enrolled and all completed the study. In the native cohort, UPCR levels decreased by 45% from baseline to week 12 (P = 0.0003). In the recurrent KT cohort, the median C3 deposit score decreased by 2.50 (scale: 0-12) on day 84 versus baseline (P = 0.03). Serum C3 levels were normalized in most patients; complement hyperactivity observed pretreatment was reduced. Severe adverse events (AEs) included post-biopsy hematuria and hyperkalemia. No deaths occurred during the study.

Conclusion

Iptacopan resulted in statistically significant and clinically important reductions in UPCR and normalization of serum C3 levels in the native cohort and reduced C3 deposit scores in the recurrent KT cohort with favorable safety and tolerability. (ClinicalTrials.gov identifier: NCT03832114).

Clinical Profiles and Patterns of Kidney Disease Progression in C3 Glomerulopathy

Key Points

Kidney survival in C3 glomerulopathy is significantly higher in patients with a disease chronicity score <4 and proteinuria <3.5 g/d, regardless of baseline eGFR. A faster eGFR decline in C3 glomerulopathy is associated with higher probability of kidney failure. Patients with glomerulopathy with a progressive reduction in proteinuria over time did not reach kidney failure.

Background

C3 glomerulopathy is a rare kidney disease, which makes it difficult to collect large cohorts of patients to better understand its variability. The aims of this study were to describe the clinical profiles and patterns of progression of kidney disease.

Methods

This was a retrospective, observational cohort study. Patients diagnosed with C3 glomerulopathy between 1995 and 2020 were enrolled. Study population was divided into clinical profiles by combining the following predictors: eGFR under/above 30 ml/min per 1.73 m2, proteinuria under/above 3.5 g/d, and histologic chronicity score under/above 4. The change in eGFR and proteinuria over time was evaluated in a subgroup with consecutive measurements of eGFR and proteinuria.

Results

One hundred and fifteen patients with a median age of 30 years (interquartile range 19–50) were included. Patients were divided into eight clinical profiles. Kidney survival was significantly higher in patients with a chronicity score <4 and proteinuria <3.5 g/d, both in those presenting with an eGFR under/above 30 ml/min per 1.73 m2. The median eGFR slope of patients who reached kidney failure was −6.5 ml/min per 1.73 m2 per year (interquartile range −1.6 to −17). Patients who showed a reduction in proteinuria over time did not reach kidney failure. On the basis of the rate of eGFR decline, patients were classified as faster eGFR decline (≥5 ml/min per 1.73 m2 per year), slower (<5 ml/min per 1.73 m2 per year), and those without decline. A faster eGFR decline was associated with higher probability of kidney failure.

Conclusions

Kidney survival is significantly higher in patients with a chronicity score <4 and proteinuria <3.5 g/d regardless of baseline eGFR, and a faster rate of decline in eGFR is associated with higher probability of kidney failure.

Octogenarians with chronic kidney disease in the nephrology clinic: Progressors vs. non-progressors

Background

The current definition of chronic kidney disease applied to patients over the age of 80 has increased the number of referrals to Nephrology. However not all of these patients may benefit from its assessment. This study aims to analyze the evolution of ≥80 years old patients referred to Nephrology.

Methods

Single-center study including patients ≥80 years old with eGFR <60 mL/min/1,73m2 who were referred to Nephrology consultation for the first time. Clinical and analytical parameters were collected retrospectively 12 months before the visit, and prospectively at baseline, and 12 and 24 months after the initial visit. We divided patients into two groups based on annual eGFR loss: progressors (>5 mL/min/1.73m2) and non-progressors (≤5 mL/min/1,73m2).

Results

A total of 318 patients were included, mean age was 84,9 ± 4 (80-97) years. Baseline serum creatinine was 1,65 ± 0,62 mg/dL, eGRF 35 (28-42) mL/min/1,73, and albumin/creatinine ratio 36 (7-229) mg/g. 55,7% of the patients met the definition of progressor at baseline (initial-progressors), 26,3% were progressors after a 12-month follow-up and 13,4% after 24 months. 21,2% and 11,4% of initial-progressors met this definition at 12 and 24 month follow up. The main risk factor for progression was albuminuria. No relationship was found between the nephrologist intervention and the evolution of renal function among initial non-progressors.

Conclusion

Elderly patients who have stable renal function at the time of referral will continue to have stable renal function over the subsequent 24 months and thus may not need to be referred to a nephrologist.

Thrombotic microangiopathy in patients with malignant hypertension

BACKGROUND

Thrombotic microangiopathy (TMA) is a complication of malignant hypertension (mHTN) attributed to the high levels of blood pressure (BP). However, no studies have investigated in patients with mHTN of different etiologies whether the presence of TMA is associated with specific causes of mHTN.

METHODS

We investigate the presence of TMA (microangiopathic hemolytic anemia and thrombocytopenia) in a large and well characterized cohort of 199 patients with mHTN of different etiologies (primary HTN 44%, glomerular diseases 16.6%, primary atypical hemolytic uremic syndrome (aHUS) 13.1%, renovascular HTN 9.5%, drug-related HTN 7%, systemic diseases 5.5%, endocrine diseases 4.5%). Outcomes of the study were kidney recovery and kidney failure.

RESULTS

Patients with TMA (40 cases, 20.1%) were younger, had a lower proportion of males, lower BP levels and worse kidney function at presentation. Their underlying diseases were primary aHUS (60%), drug-related mHTN (15%), glomerular diseases (all of them IgA nephropathy) (10%), systemic diseases (10%) and primary HTN (5%). The presence of TMA was 92.3% in primary aHUS, 42.9% in drug-related HTN, 36.4% in systemic diseases, 12.1% in glomerular diseases and 2.3% in primary HTN. No patient with renovascular HTN or mHTN caused by endocrine diseases developed TMA, despite BP levels as severe as patients with TMA. A higher proportion of TMA patients developed kidney failure as compared to patients without TMA (56.4% versus 38.9%, respectively).

CONCLUSIONS

The presence of TMA in patients with mHTN should guide the diagnosis towards primary aHUS, drug-related mHTN, some systemic diseases and IgA nephropathy, while it is exceptional in other causes of mHTN.

Development and validation of a nomogram to predict kidney survival at baseline in patients with C3 glomerulopathy

Background

C3 glomerulopathy is a rare and heterogeneous complement-driven disease. It is often challenging to accurately predict in clinical practice the individual kidney prognosis at baseline. We herein sought to develop and validate a prognostic nomogram to predict long-term kidney survival.

Methods

We conducted a retrospective, multicenter observational cohort study in 35 nephrology departments belonging to the Spanish Group for the Study of Glomerular Diseases. The dataset was randomly divided into a training group (n = 87) and a validation group (n = 28). The least absolute shrinkage and selection operator (LASSO) regression was used to screen the main predictors of kidney outcome and to build the nomogram. The accuracy of the nomogram was assessed by discrimination and risk calibration in the training and validation sets.

Results

The study group comprised 115 patients, of whom 46 (40%) reached kidney failure in a median follow-up of 49 months (range 24–112). No significant differences were observed in baseline estimated glomerular filtration rate (eGFR), proteinuria or total chronicity score of kidney biopsies, between patients in the training versus those in the validation set. The selected variables by LASSO were eGFR, proteinuria and total chronicity score. Based on a Cox model, a nomogram was developed for the prediction of kidney survival at 1, 2, 5 and 10 years from diagnosis. The C-index of the nomogram was 0.860 (95% confidence interval 0.834–0.887) and calibration plots showed optimal agreement between predicted and observed outcomes.

Conclusions

We constructed and validated a practical nomogram with good discrimination and calibration to predict the risk of kidney failure in C3 glomerulopathy patients at 1, 2, 5 and 10 years.

IgA nephropathy is the most common underlying disease in patients with anticoagulant-related nephropathy

Introduction

Anticoagulant-related nephropathy (ARN) is a relatively novel recognized entity characterized by hematuria-associated acute kidney injury (AKI) in the context of overanticoagulation. Preexisting or underlying kidney disease seems to be a predisposing factor; however, few studies have described histologic findings in patients with ARN. We aimed to evaluate underlying kidney pathology in patients on oral anticoagulation who presented an episode of AKI with hematuria in whom a kidney biopsy was performed.

Methods

Retrospective observational multicenter case study in patients treated with oral anticoagulants who developed macroscopic or intense hematuria followed by AKI. Only patients with available kidney biopsy specimens were included. Histologic findings and clinical data throughout follow-up were analyzed.

Results

A total of 26 patients were included with a median age of 75 years (62–80) and a follow-up period of 10.1 months. Of the patients, 80% were male, and most cases (92%) were on anticoagulation with vitamin K antagonists (VKAs). At admission, median serum creatinine (SCr) level was 4.2 mg/dl (2.8–8.2), median international normalized ratio (INR) 2.4 (1.5–3.4), and 11 patients (42%) required acute dialysis during hospitalization. Kidney biopsy results revealed that all patients except 1 had an underlying nephropathy: IgA nephropathy (IgAN) in 19, probable IgAN in 1, diabetic nephropathy in 3, nephrosclerosis in 1, and idiopathic nodular glomerulosclerosis in 1. At 12 weeks after discharge, only 6 subjects (24%) attained complete kidney recovery whereas 7 (28%) remained on chronic dialysis.

Conclusion

IgAN was the most common underlying kidney disease in our biopsy-proven series of ARN, in which a significant percentage of patients did not achieve kidney function recovery.

C3 glomerulopathy associated with monoclonal gammopathy: impact of chronic histologic lesions and beneficial effects of clone-targeted therapies

INTRODUCTION

C3 glomerulopathy associated with monoclonal gammopathy (C3G-MIg) is a rare entity. Herein, we analyzed the clinical and histologic features of a cohort of C3G-MIg patients.

METHODS

Retrospective, multicenter, observational study. Patients diagnosed with C3G-MIg between 1995-2021 were enrolled. All had genetic studies of the alternative complement pathway. The degree of disease activity and chronicity was analyzed using the C3G histologic index. Descriptive statistics and propensity-score matching (PSM) analysis were used to evaluate the main outcome of the study (kidney failure [KF]).

RESULTS

The study group included 23 patients: median age 63 years (IQR 48-70), 57% males. IgG kappa was the most frequent MIg (65%). The diagnosis of C3G-MIg was made in transplanted kidneys in 7 patients (30%). Five (22%) had C3 nephritic factor and 5 (22%) anti-factor H antibodies. One patient carried a pathogenic variant in CFH gene.During a follow-up of 40 months (IQR 14-69), 9 patients (39%) reached KF, and these patients had a significant higher total chronicity score in kidney biopsy. Patients who received clone-targeted therapy had a significant higher survival compared to other management. Those who achieved hematological response had a significant higher kidney survival. Outcome was remarkably poor in kidney transplant recipients, 5 of them (71%) reaching KF.By PSM (adjusting for age, kidney function, proteinuria and chronicity score), no significant differences were observed in kidney survival between C3G patients with/without MIg.

CONCLUSIONS

The C3G histologic index can be used in patients with C3G-MIg to predict kidney prognosis, with higher chronicity scores being associated with worse outcomes. Clone-targeted therapies and the development of hematological response, are associated with better kidney prognosis.

Monographic consultation of onconephrology. Rationale and implementation

The increase in demand for medical care for renal complications associated with neoplastic diseases is a reality in most nephrology departments. In response to this overall situation, the creation of healthcare models such as monographic consultations and develop training programs in Onconephrology could improve the care of these patients. Through an exploratory and descriptive study, we identified current situation of kidney involvement in cancer patients. The objective of the present study is to establish the criteria for specific assistance in the field of Onconephrology. For this, we have reviewed key aspects and analyzed the current situation in our country, through a survey addressed to all nephrologists through the Spanish Society of Nephrology., together with the experience of two Spanish centers. From this information, we have established some requirements and recommendations for the start-up of these consultations.

Low factor H-related 5 levels contribute to infection-triggered haemolytic uraemic syndrome and membranoproliferative glomerulonephritis

Dysregulation of the alternative complement pathway is a major pathogenic mechanism in two rare renal diseases: atypical haemolytic uraemic syndrome (aHUS) and membranoproliferative glomerulonephritis (MPGN). We report on a 66-year-old male with chronic hepatitis C virus (HCV) infection and a combined liver–kidney transplant that was diagnosed with MPGN at the age of 63 years and a 5-year-old boy who presented with aHUS at the age of 21 months following a Streptococcus pneumoniae infection. Both patients carried similar frameshift variants in the complement CFHR5 gene that segregate with reduced levels of factor H–related 5 (FHR-5). We conclude that low FHR-5 levels may predispose to viral and bacterial infections that then trigger different renal phenotypes.

Monographic consultation of onconephrology. Rationale and implementation

The increase in demand for medical care for renal complications associated with neoplastic diseases is a reality in most nephrology departments. In response to this overall situation, the creation of healthcare models such as monographic consultations and develop training programs in onconephrology could improve the care of these patients. Through an exploratory and descriptive study, we identified current situation of kidney involvement in cancer patients. The objective of the present study is to establish the criteria for specific assistance in the field of onconephrology. For this, we have reviewed key aspects and analyzed the current situation in our country, through a survey addressed to all nephrologists through the Spanish Society of Nephrology, together with the experience of 2 Spanish centers. From this information, we have established some requirements and recommendations for the start-up of these consultations.

Mycophenolate Mofetil in C3 Glomerulopathy and Pathogenic Drivers of the Disease

BACKGROUND AND OBJECTIVES

C3 glomerulopathy is a complement-mediated disease arising from abnormalities in complement genes and/or antibodies against complement components. Previous studies showed that treatment with corticosteroids plus mycophenolate mofetil (MMF) was associated with improved outcomes, although the genetic profile of these patients was not systematically analyzed. This study aims to analyze the main determinants of disease progression and response to this therapeutic regimen.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective, multicenter, observational cohort study in 35 nephrology departments belonging to the Spanish Group for the Study of Glomerular Diseases. Patients diagnosed with C3 glomerulopathy (n=81) or dense deposit disease (n=16) between January 1995 and March 2018 were enrolled. Multivariable and propensity score matching analyses were used to evaluate the association of clinical and genetic factors with response to treatment with corticosteroids and MMF as measured by proportion of patients with disease remission and kidney survival (status free of kidney failure).

RESULTS

The study group comprised 97 patients (84% C3 glomerulopathy, 16% dense deposit disease). Forty-two patients were treated with corticosteroids plus MMF, and this treatment was associated with a higher rate of remission and lower probability of kidney failure (79% and 14%, respectively) compared with patients treated with other immunosuppressives (24% and 59%, respectively), or ecluzimab (33% and 67%, respectively), or conservative management (18% and 65%, respectively). The therapeutic superiority of corticosteroids plus MMF was observed both in patients with complement abnormalities and with autoantibodies. However, patients with pathogenic variants in complement genes only achieved partial remission, whereas complete remissions were common among patients with autoantibody-mediated forms. The main determinant of no remission was baseline proteinuria. Relapses occurred after treatment discontinuation in 33% of the patients who had achieved remission with corticosteroids plus MMF, and a longer treatment length of MMF was associated with a lower risk of relapse.

CONCLUSIONS

The beneficial response to corticosteroids plus MMF treatment in C3 glomerulopathy appears independent of the pathogenic drivers analyzed in this study.

Characteristics, management and outcomes of atypical haemolytic uraemic syndrome in kidney transplant patients: a retrospective national study

Background

Kidney transplantation (KTx) is a strong trigger for the development of either recurrent or de novo atypical haemolytic uraemic syndrome (aHUS). According to previous studies, eculizumab (ECU) is effective for prophylaxis and for treatment of recurrence.

Methods

We evaluated the experiences of Spanish patients with recurrent and de novo aHUS associated with KTx, treated or not treated with ECU. In the de novo group, we classified patients as having early de novo (during the first month) or late de novo aHUS (subsequent onset).

Results

We analysed 36 cases of aHUS associated with KTx. All of the 14 patients with pre-KTx diagnosis of aHUS were considered to have high or moderate risk of recurrence. Despite receiving grafts from suboptimal donors, prophylactic ECU was effective for avoiding recurrence. The drug was stopped only in two cases with low–moderate risk of recurrence and was maintained in high-risk patients with no single relapse. There were 22 de novo aHUS cases and 16 belonged to the early de novo group. The median time of onset in the late group was 3.4 years. The early group had a better response to ECU than the late group, probably due to earlier diagnosis and use of the drug. No genetic pathogenic variant was detected in de novo aHUS cases, suggesting a secondary profile of the disease. ECU was stopped in all de novo patients with no relapses. ECU was well tolerated in all cases.

Conclusions

Both groups (pre-aHUS and de novo) presented different clinical profiles, management approaches and outcomes. One should consider aHUS regardless of time after KTx. Genetic studies are crucial to stratify risks of relapse and to determine necessary lengths of treatment. We suggest short ECU treatment for de novo cases without pathogenic mutation and that ECU treatment be considered pre-emptively for patients with moderate or high risk of recurrence.

Long-term validation of the renal risk score for vasculitis in a Southern European population

Background

Recently, renal risk score on the basis of three clinicopathologic features to predict end-stage renal disease (ESRD) in antineutrophil cytoplasmic antibody (ANCA)-associated renal vasculitis has been proposed. The aim of this multi-centre study was to validate this renal risk score in a large cohort of southern European patients.

Methods

Data were retrospectively collected from the time of diagnosis by systematic review of medical records from 147 patients with renal vasculitis recruited from three Spanish centres. The renal risk score was calculated in every patient, and renal and global outcomes were analysed according to the risk group assessment.

Results

ANCA serology was positive in 76.2% of patients: 64.6% showed activity against myeloperoxidase (MPO) and 12.2% against proteinase 3 (PR3). The median (interquartile range) follow-up period was 41 months (9.6–104). Forty-eight patients (32.7%) reached ESRD. Patients were classified into the three groups according to the risk of progression to ESRD: 21.8% of patients were classified into low risk, 52.4% were classified into moderate risk and the remaining 25.9% were classified into high risk. The cumulative proportion of renal survival at 2, 5 and 10 years was 100, 100 and 82% in the low-risk group, 79, 77 and 77% in the medium-risk group and 63, 53 and 40% in the high-risk group (P < 0.001). In regression analysis, the risk score was a good predictor for the development of the ESRD among ANCA positive [hazard ratio (HR) = 2.7, 95% confidence interval (CI) 1.4–4.9; P < 0.001] and ANCA negative (HR = 2.7, 95% CI 1.04–7.1, P = 0.04) patients.

Conclusions

The renal risk score constitutes an accurate tool to predict renal outcome among patients with renal vasculitis. This study contributes to validate the risk scoring system in a MPO-predominant population, but also among ANCA-negative vasculitis patients.

Urinary soluble CD163 as a biomarker of disease activity and relapse in antineutrophil cytoplasm antibody-associated glomerulonephritis

Background

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis is a chronic relapsing and remitting autoimmune disease. Urinary soluble CD163 (usCD163) has been proposed as a biomarker of active renal vasculitis. We aimed to assess the potential usefulness of usCD163 for diagnosing renal relapse in patients with ANCA-associated glomerulonephritis.

Methods

One hundred and fifty-six samples from 47 patients with ANCA-associated glomerulonephritis belonging to two different cohorts (incident and prevalent) and 20 healthy controls were studied. Patients from the incident cohort were prospectively followed up, and usCD163 concentrations were measured every 3 months. Renal relapses were identified and changes in usCD163 concentrations were analysed.

Results

Normalized usCD163 concentrations were elevated at disease onset in all patients with active renal vasculitis, with a median concentration of 601 ng/mmol (interquartile range 221–1404 ng/mmol). On the other hand, usCD163 concentrations were undetectable among control patients with renal vasculitis in remission. Except for non-responders, usCD163 concentrations progressively decreased in all patients after treatment. In the presence of vasculitis relapse, there was a consistent increase in usCD163 concentrations, compared with previous values. The area under the receiver-operating characteristic curve of absolute and relative changes in usCD163 concentrations to identify relapse of ANCA-associated glomerulonephritis was 0.96 [95% confidence interval (CI) 0.91–1.00; P = 0.001] and 0.95 (95% CI 0.90–1.00; P = 0.001), respectively. Sensitivity and specificity for a relative increase of 20%, or an absolute increase of 20 ng/mmol, in usCD163 concentrations were 100% for both, and 89.3% and 87.5%, respectively. Urinary sCD163 concentrations significantly correlated with Birmingham Vasculitis Activity Score scores at Month 6 (r = 0.737; P = 0.006) and Month 12 (r = 0.804; P = 0.005).

Conclusions

usCD163 represents an accurate biomarker for the detection of active renal vasculitis and relapse. Its close association with disease activity provides additional information for monitoring treatment response.

Update on C3 Glomerulopathy: A Complement-Mediated Disease

C3 glomerulopathy (C3G) is a clinicopathologic entity secondary to dysregulation of the alternative complement pathway in plasma and the glomerular microenvironment. The current consensus definition of C3G relies on immunofluorescence staining criteria. However, due to its high clinical variability, these criteria may not be accurate enough in some clinical scenarios. Thus, a new pathogenic classification based on a cluster analysis of clinical, histologic, and genetic data has recently been proposed, which could also help identify patients at higher risk of progression. Several pathogenic abnormalities in complement genes have been described, and the role of autoantibodies in the disease is increasingly recognized, but still the genotype-phenotype correlations in C3G are poorly understood. C3G may be diagnosed in both children and adults. The spectrum of clinical manifestations is wide, although one of the most common clinical presentations is proteinuria with relatively preserved kidney function. In order to standardize the evaluation of kidney biopsies from these patients, a histopathologic index was recently proposed, including both parameters of activity and chronicity. However, this index has not yet been validated in independent cohorts. Currently, no targeted therapies are available in clinical settings for the treatment of C3G, although several new molecules are under investigation. Treatment with corticosteroids plus mycophenolate mofetil has been shown to be associated with improved renal outcomes, as compared to other immunosuppressive regimens. Yet, the main determinants of treatment response with this regimen and the influence of the underlying pathogenic drivers have not been extensively studied. The therapeutic response to eculizumab, an anti-C5 monoclonal antibody, has been shown to be highly heterogeneous. Thus, its current clinical indication in C3G is restricted to rapidly progressive forms of the disease. To summarize, in recent years, several important advances have taken place in the understanding of C3G, but still further studies are warranted to elucidate the best therapeutic strategies that could improve prognosis of this entity.

Kidney transplant from uncontrolled donation after circulatory death donors maintained by nECMO has long-term outcomes comparable to standard criteria donation after brain death

Uncontrolled donation after circulatory death (uDCD) increases organ availability for kidney transplant (KT) with short-term outcomes similar to those obtained from donation after brain death (DBD) donors. However, heterogeneous results in the long term have been reported. We compared 10-year outcomes between 237 KT recipients from uDCD donors maintained by normothermic extracorporeal membrane oxygenation (nECMO) and 237 patients undergoing KT from standard criteria DBD donors during the same period at our institution. We further analyzed risk factors for death-censored graft survival in the uDCD group. Delayed graft function (DGF) was more common in the uDCD group (73.4% vs 46.4%; P < .01), although glomerular filtration rates at the end of follow-up were similar in the 2 groups. uDCD and DBD groups had similar rates for 10-year death-censored graft (82.1% vs 80.4%; P = .623) and recipient survival (86.2% vs 87.6%; P = .454). Donor age >50 years was associated with graft loss in the uDCD group (hazard ratio: 1.91; P = .058), whereas the occurrence of DGF showed no significant effect. uDCD KT under nECMO support resulted in similar graft function and long-term outcomes compared with KT from standard criteria DBD donors. Increased donor age could negatively affect graft survival after uDCD donation.

Where are we with haemolytic uremic syndrome?

Haemolytic uremic syndrome (HUS) is characterised by microangiopathic haemolytic anaemia with acute kidney injury. It is currently classified into two main categories: Shiga-toxin producing E. coli-hemolytic uremic syndrome (STEC-HUS) and atypical haemolytic uremic syndrome (aHUS). Endothelial cell damage is the common pathway in HUS to developing thrombotic microangiopathy. Atypical HUS includes primary, secondary and aHUS due to metabolic diseases. In the majority of aHUS cases, hyperactivity of the alternative complement pathway plays a central role. Therefore, treatment is based on complement inhibitors like eculizumab, a drug that has revolutionised the natural history of the disease. Relapses are frequent after kidney transplant and thus confer a poor prognosis.

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.

A retrospective study of pregnancy-associated atypical hemolytic uremic syndrome

Pregnancy-associated atypical hemolytic uremic syndrome (aHUS) refers to the thrombotic microangiopathy resulting from uncontrolled complement activation during pregnancy or the postpartum period. Pregnancy-associated aHUS is a devastating disease for which there is a limited clinical understanding and treatment experience. Here we report a retrospective study to analyze the clinical and prognostic data of 22 cases of pregnancy-associated aHUS from the Spanish aHUS Registry under different treatments. Sixteen patients presented during the first pregnancy and as many as nine patients required hemodialysis at diagnosis. Identification of inherited complement abnormalities explained nine of the 22 cases, with CFH mutations and CFH to CFHR1 gene conversion events being the most prevalent genetic alterations associated with this disorder (66%). In thirteen of the cases, pregnancy complications were sufficient to trigger a thrombotic microangiopathy in the absence of genetic or acquired complement alterations. The postpartum period was the time with highest risk to develop the disease and the group shows an association of cesarean section with pregnancy-associated aHUS. Seventeen patients underwent plasma treatments with a positive renal response in only three cases. In contrast, ten patients received eculizumab with an excellent renal response in all, independent of carrying or not inherited complement abnormalities. Although the cohort is relatively small, the data suggest that pregnancy-associated aHUS is not different from other types of aHUS and suggest the efficacy of eculizumab treatment over plasma therapies. This study may be useful to improve prognosis in this group of aHUS patients.

Remission of Hematuria Improves Renal Survival in IgA Nephropathy

Hematuria is a cardinal symptom in IgA nephropathy, but its influence on the risk of disease progression has been scarcely investigated. We followed a cohort of 112 patients with IgA nephropathy for a mean±SEM period of 14±10.2 years, during which clinical and analytic risk factors (including urine sediment examination) were regularly recorded. According to the magnitude of time-averaged hematuria, we classified patients as those with persistent hematuria and those with negative or minimal hematuria. We also classified patients according to the magnitude of time-averaged proteinuria (>0.75 or ≤0.75 g/d). The proportion of patients reaching ESRD or a 50% reduction of renal function was significantly greater among patients with persistent hematuria than patients with minimal or negative hematuria (30.4% and 37.0% versus 10.6% and 15.2%, respectively; P=0.01). Multivariable analysis revealed time-averaged hematuria, time-averaged proteinuria, renal function at baseline, and the presence of tubulointerstitial fibrosis on renal biopsy as independent predictors of ESRD. After hematuria disappearance, which occurred in 46% of the patients, the rate of renal function decline changed from -6.45±14.66 to -0.18±2.56 ml/min per 1.73 m² per year (P=0.001). Patients with time-averaged proteinuria >0.75 g/d had significantly poorer renal survival than those with time-averaged proteinuria ≤0.75 g/d. However, on further classification by time-averaged hematuria, only those patients with time-averaged proteinuria >0.75 g/d and persistent hematuria had significantly worse renal survival than those in the other three groups. In conclusion, remission of hematuria may have a significant favorable effect on IgA nephropathy outcomes.

Renal vasculitis presenting with acute kidney injury

Renal failure secondary to ANCA-associated vasculitis represents a clinical and therapeutic challenge. In this study, we aimed to assess the treatment response rates and long-term outcomes of vasculitis patients presenting with renal failure. This retrospective study included 151 patients with renal vasculitis from three hospitals who underwent a renal biopsy between 1997 and 2014. Patients with renal failure which required dialysis at the onset were compared to those presenting with more preserved renal function. The primary end point was treatment response and patient surivival. Patients with severe renal involvement had a lower response to treatment compared to those having preserved renal function (26.6 versus 93.4%; p < 0.001). Dialysis-dependent patients who received plasmapheresis in addition to immune suppressants associated a higher rate of renal recovery (41.6 versus 12.5%; p = 0.05). A higher incidence of severe infections was observed among patients with severe renal involvement (38.4 versus 18.1%, p = 0.01). The mortality rate was significantly higher among vasculitis patients presenting with renal failure (53.8 versus 22.2%, p = 0.001). Global survival at 1 and 5 years was 60 and 47% in patients requiring dialysis compared with 90 and 80% among those with more preserved renal function (p < 0.001). After multivariate adjustment, the need for dialysis remained as an independent predictor of death (HR 2.5; 95% CI 1.1-5.7; p = 0.03). The presence of severe renal dysfunction represents an independent risk factor for patient survival in renal vasculitis. Patients requiring dialysis associate a lower response rate to immunosuppressive therapy and a higher incidence of severe infections.

The predictive value of kidney biopsy in renal vasculitis: a multicenter cohort study

The histopathologic classification of antineutrophil cytoplasmic antibody-associated vasculitis has been demonstrated to have prognostic value in small cohorts of patients with pauci-immune extracapillary glomerulonephritis. We aimed to validate this histologic subgrouping system in a large cohort of patients with renal vasculitis from 3 Spanish centers. The additional value of several histologic parameters for predicting renal outcome was investigated. A total of 151 biopsies of patients with renal vasculitis were reviewed and classified as follows: 41% crescentic, 24% mixed, 21% focal, and 14% sclerotic. The cumulative proportions of renal survival at 5 years were 83.2%, 81.2%, 60.5%, and 50.7% for the focal, mixed, crescentic, and sclerotic categories, respectively (P < .05). In the crescentic category, patients with less than 75% of glomeruli showing crescents had better survival at 1 and 5 years compared with those having greater than or equal to 75% of crescents (77.9% and 70.6% versus 51.3% and 45.6%; P = .02). When adjusted by renal function and other histologic parameters, the percentage of extracapillary proliferation and glomerulosclerosis remained as significant predictors for renal survival (hazard ratio, 1.03; 95% confidence interval, 1.01-1.05; P = .001, and hazard ratio, 1.03; 95% confidence interval, 1.01-1.05; P = .002, respectively). In conclusion, patients with pauci-immune crescentic glomerulonephritis experienced different outcomes depending on the percentage of crescents observed, so that extensive extracapillary proliferation was associated with the poorest renal survival. These findings validate the prognostic utility of the histologic classification scheme in antineutrophil cytoplasmic antibody positive and negative patients and suggest a subdivision of crescentic category (<75% and ≥75% of crescents) based on the different survival rates observed among these subgroups.

Rituximab for treatment of severe renal disease in ANCA associated vasculitis

BACKGROUND

Rituximab (RTX) is approved for remission induction in ANCA associated vasculitis (AAV). However, data on use of RTX in patients with severe renal disease is lacking.

METHODS

We conducted a retrospective multi-center study to evaluate the efficacy and safety of RTX with glucocorticoids (GC) with and without use of concomitant cyclophosphamide (CYC) for remission induction in patients presenting with e GFR less than 20 ml/min/1.73 m(2). We evaluated outcomes of remission at 6 months (6 M), renal recovery after acute dialysis at diagnosis, e-GFR rise at 6 M, patient and renal survival and adverse events.

RESULTS

A total 37 patients met the inclusion criteria. The median age was 61 years. (55-73), 62 % were males, 78 % had new diagnosis and 59 % were MPO ANCA positive. The median (IQR) e-GFR at diagnosis was 13 ml/min/1.73 m(2) (7-16) and 15 required acute dialysis. Eleven (30 %) had alveolar hemorrhage. Twelve (32 %) received RTX with GC, 25 (68 %) received RTX with GC and CYC and seventeen (46 %) received plasma exchange. The median (IQR) follow up was 973 (200-1656) days. Thirty two of 33 patients (97 %) achieved remission at 6 M and 10 of 15 patients (67 %) requiring dialysis recovered renal function. The median prednisone dose at 6 M was 6 mg/day. The mean (SD) increase in e-GFR at 6 months was 14.5 (22) ml/min/m(2). Twelve patients developed ESRD during follow up. There were 3 deaths in the first 6 months. When stratified by use of concomitant CYC, there were no differences in baseline e GFR, use of plasmapheresis, RTX dosing regimen or median follow up days between the groups. No differences in remission, renal recovery ESRD or death were observed.

CONCLUSIONS

This study of AAV patients with severe renal disease demonstrates that the outcomes appear equivalent when treated with RTX and GC with or without concomitant CYC.

Malignant hypertension: a type of IgA nephropathy manifestation with poor prognosis

INTRODUCTION

&nbsp;Malignant hypertension (MHT) is an uncommon clinical manifestation of IgA Nephropathy (IgAN). Its prevalence, pathogenesis and evolution are not well known.&nbsp;

MATERIAL AND METHODS

&nbsp;We performed a descriptive and retrospective study to report the clinical characteristics and evolution of thirteen patients diagnosed as having IgA nephropathy by renal biopsy in our hospital who developed MHT (IgAN-MHT).&nbsp;

RESULTS

&nbsp;The prevalence of MHT in our IgAN patients was 7% (13/186). The mean age was 37&plusmn;12 years and 84% were males. Mean systolic/diastolic blood pressure at presentation were 219&plusmn;32/132&plusmn;18mmHg, respectively. Renal function impairment was detected at admission in all the patients, with a mean serum creatinine of 4.73&plusmn;3.12mg/dL. No patient showed analytical data that suggested thrombotic microangiopathy. Renal biopsies showed mild chronicity lesions and only four patients presented features of thrombotic microangiopathy. All patients were treated with renin-angiotensin-aldosterone blockers and two received steroids. They all showed a progressive loss of renal function. At the end of follow up one patient had died, ten were on chronic dialysis and two presented chronic kidney disease stage 3b. Renal survival was 69% and 35% at 3 and 6 years, respectively. Six patients received a kidney transplant: IgAN relapsed in four patients. One of them presented a new episode of MHT associated with a HELLP syndrome.&nbsp;

CONCLUSIONS

&nbsp;Malignant hypertension is a form of IgAN clinical presentation having a remarkably worse renal outcome and without specific effective treatment.

When should a nephrologist suspect a mitochondrial disease?

Mitochondrial diseases, taking into account those that affect the processes of the respiratory chain (RC) and mitochondrial oxidative phosphorylation system (OXPHOS), make up a relatively frequent group within rare diseases that usually have multisystem involvement, a very variable phenotypic expression and a complex genetic base. Renal involvement is uncommon, with the tubule being the most affected, specifically its proximal portion, developing into full Toni-Debr&eacute;-Fanconi syndrome in the most serious cases. However, in some cases the glomerulus is involved, fundamentally in focal segmental glomerulosclerosis form (FSGS), expressed by proteinuria and renal failure. It is important that the Nephrologist keeps in mind the possibility of a mitochondrial disease in patients with this type of renal involvement that present clinical data with these characteristics, especially diabetes mellitus and deafness. In cases with FSGS, a correct diagnosis will avoid the inappropriate use of immunosuppressive medication. Specific treatments do not exist for the majority of mitochondrial diseases, but it is likely that the intense research that currently exists for these diseases will eventually produce effective treatment possibilities.