Randomized controlled trial of mycophenolate mofetil in children, adolescents, and adults with IgA nephropathy

Treatment of IgA Nephropathy: Evolution Over Half a Century

Fifty years into the original description of IgA nephropathy, there is still no specific therapy for this condition and general measures including blood pressure control with blockers of the renin-angiotensin-aldosterone system and salt restriction remain the cornerstone to slow disease progression. Although the paucity in treatment advances could be related to the disease's complex pathogenesis, which requires multiple hits, heterogeneity as reflected by diverse ethnic differences, and genetic predisposition and histopathologic variations, many nonspecific and immunomodulatory agents have been tested with variable degrees of success and tribulations. Here, we review the evolution of these different therapeutic approaches over time that culminated in the 2012 Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for Glomerulonephritis that presently is being updated, and provide an appraisal of recent data on various forms of immunosuppressive agents. Finally, we discuss the theoretical basis of ongoing and upcoming clinical trials that are more pathway- or cell-type-specific as knowledge in disease mechanisms advances.

Efficacy and safety of glucocorticoids for patients with IgA nephropathy: a meta-analysis

BACKGROUND

The efficacy and safety of glucocorticoids for the treatment of patients with IgA nephropathy (IgAN) remains controversial. The aim of the study is to perform a metaanalysis of randomized controlled trials to evaluate the efficacy and safety of glucocorticoids for patients with IgAN.

METHODS

We searched PubMed, EMBASE and the Cochrane Library and article reference lists of Controlled Trials, and Clinical Trial Registries for randomized controlled trials comparing glucocorticoids with other non-immunosuppressive agents in patients with IgAN.

RESULTS

The present meta-analysis, including 10 RCTs and 791 patients from 12 published studies, showed that using glucocorticoids agents relatively preserves kidney function(RR 0.06, 95% CI 0.14-0.61) and plays an effective role on reducing the proteinuria(SMD, - 0.69; 95% CI 0.85 to - 0.53, p < 0.00001; heterogeneity I2 = 0%; p = 0.09) compared with a control group. Moreover, adverse events cannot be neglected, especially gastrointestinal tract (RR 3.10, 95% CI 1.37-6.98, p = 0.006; heterogeneity I2 = 0%, p = 0.86), and corticosteroid regimens in IgAN should be reviewed with regard to safety.

CONCLUSIONS

Glucocorticoids were wildly used to treat various diseases including IgAN. Meanwhile, adverse events cannot be neglected, such as gastrointestinal adverse events, infection and so on. Corticosteroid should be used with reserve, especially in those patients with hypertension and impaired renal function or older patients.

Combination therapy with or without warfarin and dipyridamole for severe childhood IgA nephropathy: an RCT

BACKGROUND

Two previous randomized controlled trials showed that treatment of severe childhood immunoglobulin A (IgA) nephropathy using prednisolone with azathioprine, heparin-warfarin, or dipyridamole prevented the increase of sclerosed glomeruli. Prednisolone alone, however, did not prevent further increase. These studies indicated the importance of immunosuppressants in the treatment. An additional pilot study using mizoribine instead of azathioprine enabled us to complete 2 years of combined regimen. It showed non-numerical inferior effectiveness compared with the azathioprine regimen. Further examination of the additional efficacy of warfarin and dipyridamole was required.

METHODS

A randomized control trial of prednisolone and mizoribine with (group 1) or without (group 2) warfarin and dipyridamole was administered for treatment of 71 children with severe IgA nephropathy to evaluate the efficacy of additional warfarin and dipyridamole.

RESULTS

Thirty of 34 patients (88.2%) in group 1, and 27 of 36 patients (75.0%) showed the disappearance of proteinuria as defined by early morning urinary protein to creatinine ratio of < 0.2 during the 2-year treatment period. The cumulative disappearance rate of proteinuria determined by the Kaplan-Meier method showed that the disappearance rate of proteinuria was significantly higher in group 1 than in group 2 (log-rank P = 0.04). There was no significant difference in pathological findings, but there was a tendency of increase of global sclerosis in group1 which might be related to warfarin. Most of the adverse effects were related to prednisolone, but fortunately transient.

CONCLUSIONS

The balance between minimal benefits of warfarin/dipyridamole and potential adverse effects may be in favor of avoiding them in children with IgA nephropathy.

The Emerging Role of Pathogenesis of IgA Nephropathy

IgA nephropathy is an autoimmune disease induced by fthe ormation of galactose-deficient IgA1 and anti-glycans autoantibody. A multi-hit hypothesis was promoted to explain full expression of IgA nephropathy. The deposition of immune complex resulted in activation of the complement, increasing oxidative stress, promoting inflammatory cascade, and inducing cell apoptosis via mesangio-podocytic-tubular crosstalk. The interlinked signaling pathways of immune-complex-mediated inflammation can offer a novel target for therapeutic approaches. Treatments of IgA nephropathy are also summarized in our review article. In this article, we provide an overview of the recent basic and clinical studies in cell molecular regulation of IgAN for further treatment interventions.

Efficacy and safety of mycophenolate mofetil for IgA nephropathy: An updated meta-analysis of randomized controlled trials

The efficacy and safety of mycophenolate mofetil (MMF) for immunoglobulin A nephropathy (IgAN) remains debatable. Therefore, the present meta-analysis was conducted with randomized controlled trials (RCTs). PubMed/MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were analyzed to identify eligible trials. The pooled risk ratio (RR) with 95% confidence interval (CI) was estimated for all the dichotomous outcome measures. A total of eight RCTs with nine publications (n=510 patients) were included. No significant difference was noted between therapeutic regimens with and without MMF for renal remission and end stage renal disease (ESRD) of patients with IgAN (seven trials; RR, 1.250; 95% CI, 0.993–1.574; P=0.057; and four trials; RR, 0.728; 95% CI, 0.164–3.236; P=0.676). To further define the effects of MMF for renal remission, subgroup analysis was performed, demonstrating that MMF was significantly more effective compared with the placebo (three trials; RR, 2.152; 95% CI, 1.198–3.867; P=0.010), although the immunosuppressive regimens with MMF had no significantly different effects compared with those without MMF (four trials; RR, 1.140; 95% CI, 0.955–1.361; P=0.146), indicating that MMF was superior to placebo and had a similar efficacy to other immunosuppressants for renal remission. In addition, subgroup analysis for ESRD revealed no significant differences between MMF and placebo and between the immunosuppressive regimens with and without MMF (three trials; RR, 0.957; 95% CI, 0.160–5.726; P=0.962; and one trial; RR, 0.205; 95% CI, 0.010–4.200; P=0.303). Furthermore, there were no significant differences between the therapeutic regimens with and without MMF in terms of the risk of adverse events. The present meta-analysis demonstrated that MMF was more effective compared with the placebo, may have similar efficacy to other immunosuppressants in terms of inducing renal remission of IgAN and may not increase the risk of adverse events. The long-term effects of MMF on the prognosis of patients with IgAN require verification in further studies.

Immunosuppression in IgA Nephropathy: Guideline Medicine Versus Personalized Medicine

The role of immunosuppression in IgAN remains controversial despite a growing evidence base of randomized controlled trials (RCTs). In IgAN with nephrotic syndrome the role for corticosteroids is limited to cases with minimal change on light microscopy. In crescentic IgAN, the use of immunosuppression is supported only by anecdotal data, and outcome may be poor especially when glomerular filtration rate is impaired severely at presentation or there are pathologic features of chronic injury. In slowly progressive IgAN, prediction of outcome now is based both on clinical and pathologic features. Most RCTs have studied patients with urine protein levels greater than 1 g/24 h and only a minority have enrolled patients with a glomerular filtration rate less than 60 mL/min. The Supportive versus immunosuppressive Therapy of Progressive IgA nephropathy (STOP) IgAN study emphasized the efficacy of supportive therapy (including blood pressure control and renin-angiotensin system blockade) in decreasing proteinuria to less than the usually accepted threshold for the use of corticosteroids. Earlier RCTs of corticosteroids usually did not deploy supportive therapy optimally. The recent Therapeutic Evaluation of STeroids in IgA Nephropathy Global (TESTING) study closed prematurely because of excess toxicity, but the high dose of corticosteroids seemed to provide benefit. Guidelines provide valuable information about the quality and limitations of available evidence that needs to be personalized in application to the individual patient's medical and nonmedical circumstances to ensure wise clinical decision making.

Primary IgA nephropathy: current challenges and future prospects

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide, exhibiting a variable clinical and pathological course and significantly contributing to the global burden of chronic kidney disease and end-stage renal disease. Current standards of care focus on optimization of antihypertensive and antiproteinuric therapies (typically renin- angiotensin system blockade) to reduce disease progression. Much recent attention has focused on whether additional immunosuppression confers better outcomes than supportive management alone, and indeed, several trials have demonstrated renoprotective effects following the use of oral corticosteroids. However, results have been inconsistent, and perceived benefits must be balanced against risks and adverse effects associated with generalized immunosuppression, as highlighted by the high-profile STOP-IgAN and TESTING clinical trials. Recent translational research in vitro and animal models of IgAN have generated greater insight into potential therapeutic targets for this complex autoimmune disease. Deeper understanding of the roles of the mucosal immune barrier, complement activation and deposition, T-cell dependent and independent mechanisms of B cell activation, and of the deposition and downstream inflammatory signaling pathways of nephritogenic polymeric IgA1 complexes (e.g., signaling of immune receptors via spleen tyrosine kinase) has formed the rationale for the development of novel agents and clinical trials of more targeted therapies. However, translating findings into clinical practice is challenging, with many immunopathological features of IgAN specific to humans. Recent comprehensive reviews outline current understanding of mechanisms of IgAN as well as ongoing and future clinical trials; it is not our aim to replicate this here. Instead, we take a mechanistic approach to current treatment strategies, outlining advantages and limitations of each before exploring ongoing research with potential translation into future targeted therapies for this complex disease.

Comparative Efficacy and Safety of Therapies in IgA Nephropathy: A Network Meta-analysis of Randomized Controlled Trials

The present study aims to compare the relative efficacy and safety of different interventions for IgA nephropathy (IgAN) with proteinuria more than 1 g/d by using network meta-analysis. We searched PubMed, Embase, and the Cochrane Library for studies compared the rate of clinical remission and/or end-stage renal disease (ESRD) and/or serious adverse events in IgAN patients with proteinuria (>1 g/d). The surface under the cumulative ranking area (SUCRA) was calculated to rank the interventions. A total of 21 randomized controlled trials with 1822 participants were included for the comparisons of 7 interventions. The rank of the most effective treatments to induce clinical remission was renin−angiotensin system inhibitors (RASi) plus urokinase, steroid plus tonsillectomy, and RASi plus steroid with a SUCRA of 0.912, 0.710, and 0.583, respectively. As for the prevention of ESRD or doubling of serum creatinine, RASi plus steroid (SUCRA 0.012) was the most effective, followed by RASi (SUCRA 0.282) and steroid (SUCRA 0.494), leaving mycophenolate mofetil as the least effective (SUCRA 0.644). There was no statistical difference among all interventions in the occurrence of serious adverse events. The current network meta-analysis demonstrated for the first time that RASi plus steroid is probably the best therapeutic choice, not only for reducing proteinuria but also for maintaining long-term renal protection.

Inflammation in IgA nephropathy

Immunoglobulin A nephropathy (IgAN) is the most frequently occurring primary glomerulonephritis in Caucasian and Asian populations. Nonetheless, therapeutic recommendations are based on weak evidence, large controlled trials are scarce and, in particular, the additional value of immunosuppression beyond comprehensive supportive measures is not well-established. The use of immunosuppressants is supported by experimental insights into IgAN pathogenesis that suggest an autoimmune component in disease development. The so-called "multi-hit" theory comprises multiple steps, starting with defective glycosylation of IgA subclass IgA1 that results in overproduction of galactose-deficient IgA1 (Gd-IgA1), occurrence of anti-Gd-IgA1 autoantibodies, and mesangial deposition of nephritogenic immune complexes. This eventually results in an increased mesangial cell proliferation, inflammatory responses, and complement activation. Recent genome-wide association studies have identified several susceptibility genes, many of which support the "multi-hit" concept. In light of these discoveries, it is astonishing that the vast majority of adult IgAN patients obviously do not need and/or benefit from immunosuppressive therapies in the first place. In fact, a number of supportive measures are highly effective in reducing the risk for disease progression in many patients. These measures need to be optimized before immunosuppression should be considered at all. In this review we focus on the underlying pathogenetic cornerstones and the central question of whether systemic inflammation in adult IgAN patients should be treated. Treatment options in children with IgAN are also discussed.

Effects of Two Immunosuppressive Treatment Protocols for IgA Nephropathy

The role of immunosuppression in IgA nephropathy (IgAN) is controversial. In the Supportive Versus Immunosuppressive Therapy for the Treatment of Progressive IgA Nephropathy (STOP-IgAN) Trial, 162 patients with IgAN and proteinuria >0.75 g/d after 6 months of optimized supportive care were randomized into two groups: continued supportive care or additional immunosuppression (GFR≥60 ml/min per 1.73 m²: 6-month corticosteroid monotherapy; GFR=30-59 ml/min per 1.73 m²: cyclophosphamide for 3 months followed by azathioprine plus oral prednisolone). Coprimary end points were full clinical remission and GFR loss ≥15 ml/min per 1.73 m² during the 3-year trial phase. In this secondary intention to treat analysis, we separately analyzed data from each immunosuppression subgroup and the corresponding patients on supportive care. Full clinical remission occurred in 11 (20%) patients receiving corticosteroid monotherapy and three (6%) patients on supportive care (odds ratio, 5.31; 95% confidence interval, 1.07 to 26.36; P=0.02), but the rate did not differ between patients receiving immunosuppressive combination and controls on supportive care (11% versus 4%, respectively; P=0.30). The end point of GFR loss ≥15 ml/min per 1.73 m² did not differ between groups. Only corticosteroid monotherapy transiently reduced proteinuria at 12 months. Severe infections, impaired glucose tolerance, and/or weight gain in the first year were more frequent with either immunosuppressive regimen than with supportive care. In conclusion, only corticosteroid monotherapy induced disease remission in a minority of patients who had IgAN with relatively well preserved GFR and persistent proteinuria. Neither immunosuppressive regimen prevented GFR loss, and both associated with substantial adverse events.

Mycophenolate mofetil therapy in immunoglobulin A nephropathy: histological changes after treatment

Background

Endocapillary hypercellularity independently predicts renal outcome in immunoglobulin A nephropathy (IgAN). Mycophenolate mofetil (MMF) treatment is offered to patients presenting to the Imperial College Renal and Transplant Centre with IgAN and histological evidence of endocapillary hypercellularity. Clinical trials of MMF in IgAN have been inconclusive and have been limited by a lack of specific histological inclusion and exclusion criteria when recruiting patients. Evidence of histological improvement following MMF treatment would support its therapeutic use. We therefore reviewed histological changes after MMF therapy in a cohort of IgAN patients.

Method

Eighteen IgAN patients with native renal biopsies before and after repeated MMF treatment were identified. Patients were excluded if they had received any other immunosuppressive therapy, including corticosteroids. On the basis of the Oxford Classification of IgAN, we reviewed histological changes after MMF treatment.

Results

Nine patients (50%) were male. At diagnostic renal biopsy, the median age was 35 years [interquartile range (IQR) 30-41], serum creatinine was 97 µmol/L (IQR 79-153) and urine protein creatinine ratio (UPCR) was 146 mg/mmol (IQR 98-212). The median time between biopsies was 24 months (range 9-41). Following MMF treatment, repeat biopsy demonstrated statistically significant improvement in the mean percentage of glomeruli showing endocapillary hypercellularity and cellular/fibrocellular crescents. There was no change in mesangial hypercellularity, segmental sclerosis or tubular atrophy scores. Mesangial IgA deposition was also significantly reduced. Histopathological improvement persisted after the cessation of MMF therapy, suggesting that 2 years of treatment is adequate for benefit. The median serum creatinine remained stable at 3 years follow-up at 104 µmol/L (IQR 79-147).

Conclusion

MMF treatment is associated with histopathological improvement in IgAN.

Is there a role for immunosuppression in immunoglobulin A nephropathy?

The most common primary glomerular disease globally is IgA nephropathy (IgAN). It is often a slowly progressive disease, and ∼40% of patients will progress to kidney failure. Due to a lack of large clinical trial networks and a lack of surrogate markers of treatment efficacy, there are relatively few large multicenter clinical trials in IgAN. Given that both the pathogenesis and progression of IgAN are linked to defects in mucosal immune regulation and inflammation, use of immunosuppression to prevent kidney failure is well founded. However, recent clinical trials have supported improvement in disease parameters, but this has not always translated to parallel amelioration in longer-term outcome. In this review we summarize the most current clinical research examining the efficacy of immunosuppression in IgAN.

Efficacy and safety of mycophenolate mofetil in patients with IgA nephropathy: an update meta-analysis

BACKGROUND

The application of mycophenolate mofetil (MMF) in treating patients with immunoglobulin A nephropathy (IgAN) remains uncertain. This update meta-analysis was performed to re-evaluate the therapeutic potential of MMF in IgAN.

METHODS

Articles were obtained by searching the electronic databases without language restriction. Randomized controlled trials studying the role of MMF in treating IgAN were collected. The quality of included studies was critically evaluated. Data analyses were performed by using RevMan 5.3 software.

RESULTS

A total of 297 articles were screened and eight articles were finally included. Among the eight randomized controlled trials, five and three were high quality and low quality, respectively. Both fixed-effect and random-effect model were used. Pooled results by combining all the eight studies suggested that IgAN patients in MMF group had a higher remission rate than that in control group. Compared to placebo or corticosteroid monotherapy, MMF monotherapy exerted a higher remission rate and side effect rate in both main analysis and subgroup analysis by human race. Compared to corticosteroid plus other immunosuppressive agent therapy, corticosteroid plus MMF therapy had a higher remission rate, lower serum creatinine doubling rate, progression to end-stage renal disease rate and side effects rate. Subgroup analysis by therapeutic regimen further confirmed these results between corticosteroid plus MMF therapy and corticosteroid plus cyclophosphamide therapy. Funnel-plot displayed a symmetrical figure, indicating no publication bias existed.

CONCLUSIONS

MMF has the potential in treatment of IgAN, especially for Asians. The evidence currently available shows that MMF monotherapy has a more efficacy but higher side effects when compared to placebo or corticosteroid monotherapy in treatment of Asians with IgAN. While MMF combined with corticosteroid regimen has a more efficacy and lower side effects when compared with corticosteroid plus cyclophosphamide regimen.

IgA Nephropathy

IgA nephropathy (IgAN) is a leading cause of CKD and renal failure. Recent international collaborative efforts have led to important discoveries that have improved our understanding of some of the key steps involved in the immunopathogenesis of IgAN. Furthermore, establishment of multicenter networks has contributed to rigorous design and execution of clinical trials that have provided important insights regarding immunotherapy in IgAN. In this article, we review emerging developments in clinical and translational IgAN research and describe how these novel findings will influence future strategies to improve the outcome of patients with IgAN.

A Randomized, Controlled Trial of Rituximab in IgA Nephropathy with Proteinuria and Renal Dysfunction

IgA nephropathy frequently leads to progressive CKD. Although interest surrounds use of immunosuppressive agents added to standard therapy, several recent studies have questioned efficacy of these agents. Depleting antibody-producing B cells potentially offers a new therapy. In this open label, multicenter study conducted over 1-year follow-up, we randomized 34 adult patients with biopsy-proven IgA nephropathy and proteinuria >1 g/d, maintained on angiotensin-converting enzyme inhibitors or angiotensin receptor blockers with well controlled BP and eGFR<90 ml/min per 1.73 m², to receive standard therapy or rituximab with standard therapy. Primary outcome measures included change in proteinuria and change in eGFR. Median baseline serum creatinine level (range) was 1.4 (0.8-2.4) mg/dl, and proteinuria was 2.1 (0.6-5.3) g/d. Treatment with rituximab depleted B cells and was well tolerated. eGFR did not change in either group. Rituximab did not alter the level of proteinuria compared with that at baseline or in the control group; three patients in each group had ≥50% reduction in level of proteinuria. Serum levels of galactose-deficient IgA1 or antibodies against galactose-deficient IgA1 did not change. In this trial, rituximab therapy did not significantly improve renal function or proteinuria assessed over 1 year. Although rituximab effectively depleted B cells, it failed to reduce serum levels of galactose-deficient IgA1 and antigalactose-deficient IgA1 antibodies. Lack of efficacy of rituximab, at least at this stage and severity of IgA nephropathy, may reflect a failure of rituximab to reduce levels of specific antibodies assigned salient pathogenetic roles in IgA nephropathy.

Con: STOP immunosuppression in IgA nephropathy

A comprehensive supportive therapy approach constitutes the mainstay treatment of IgA nephropathy (IgAN) patients. In our recent Supportive versus immunosuppressive Therapy Of Progressive IgA Nephropathy (STOP-IgAN) trial, we systematically selected for patients at high risk of a progressive disease course and evaluated the effect of immunosuppression, combined with supportive care, on renal end points in these patients. There was a higher rate of full clinical remission and transient proteinuria reduction in immunosuppressed patients. However, deterioration of renal function (i.e. number of patients with an estimated glomerular filtration rate (eGFR) decrease of at least 15 mL/min over the 3-year trial phase) was remarkably slow in both groups, compared with previous studies, and was not slowed further by adding immunosuppression to supportive care. Here, we address several concerns raised on the design and interpretation of our trial. In our randomized patients, we confirmed a lower baseline proteinuria to be predictive of clinical remission in IgAN. However, the observed transient drop in proteinuria in the immunosuppressed patients did not translate into an improved overall renal outcome in these patients. Although longer follow-up would be desirable, there was not even a trend for the eGFR course to diverge between our two treatment arms during the trial phase. Finally, it is important to note that we excluded specific infrequent patient groups during our run-in phase. Therefore, IgAN patients with a rapidly progressing course and those with persistent proteinuria >3.5 g/day would require further evaluation regarding potential benefits of immunosuppressive therapies.

Spleen Tyrosine Kinase: A Crucial Player and Potential Therapeutic Target in Renal Disease

Spleen tyrosine kinase (Syk), a 72 kDa cytoplasmic non-receptor protein-tyrosine kinase, plays an important role in signal transduction in a variety of cell types. Ever since its discovery in the early 1990s, there has been accumulating evidence to suggest a pathogenic role of Syk in various allergic disorders, autoimmune diseases and malignancies. Additionally, there is emerging data from both pre-clinical and clinical studies that Syk is implicated in the pathogenesis of proliferative glomerulonephritis (GN), including anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic antibody-associated GN, lupus nephritis and immunoglobulin A nephropathy (IgAN). Moreover, recent animal studies have shed light on the importance of Syk in mediating acute renal allograft rejection, Epstein Barr virus-associated post-transplant lymphoproliferative disease and kidney fibrosis. Fostamatinib, an oral Syk inhibitor, has undergone clinical testing in rheumatoid arthritis, refractory immune thrombocytopenic purpura, leukemia and lymphoma. The recent STOP-IgAN trial showed that the addition of non-selective immunosuppressive therapy to intensive supportive care did not improve clinical outcomes in high-risk IgAN patients. A Syk-targeted approach may be beneficial and is currently being evaluated in a phase II randomized controlled trial. In this review, we will discuss the pathogenic role of Syk and potential use of Syk inhibitor in a variety of renal diseases.

[IgA nephropathy]

IgA nephropathy is the most common form of primary glomerulonephritis worldwide and an important cause of chronic kidney disease and end-stage kidney failure. Its pathophysiology remains in part unsolved but it is recognized as an immune complex disease. Recent years have brought progress in the field through the discovery of several genetic susceptibility loci and the formulation of the multi-hit pathogenesis model. Presentation, clinical course and histology can be extremely variable, making any histological classification still difficult. Indeed, most therapeutic studies until now include patients based only on the severity of clinical criteria but the new classification of Oxford should change that. Only the management of patients with nephropathy with minimal change glomerular lesions and nephrotic syndrome, or extra-capillary glomerulonephritis and rapidly progressive renal failure, is consensual: Corticosteroids alone for the first and associated with immunosuppressive drugs for the latter. The recent Kidney Disease Improving Global Outcomes (KDIGO) consensus treatment guideline is still controversial, especially in light of the last clinical studies. Corticosteroid therapy can be discussed in patients with proteinuria greater than 1 g/day without renal failure. All IgA nephropathy patients should benefit from the global management of chronic glomerular disease, including a renin-angiotensin system blocker in the presence of hypertension or proteinuria.

Primary glomerulonephritides

Most glomerulonephritides, even the more common types, are rare diseases. They are nevertheless important since they frequently affect young people, often cannot be cured, and can lead to chronic kidney disease, including end-stage renal failure, with associated morbidity and cost. For example, in young adults, IgA nephropathy is the most common cause of end-stage renal disease. In this Seminar, we summarise existing knowledge of clinical signs, pathogenesis, prognosis, and treatment of glomerulonephritides, with a particular focus on data published between 2008 and 2015, and the most common European glomerulonephritis types, namely IgA nephropathy, membranous glomerulonephritis, minimal change disease, focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis, and the rare complement-associated glomerulonephritides such as dense deposit disease and C3 glomerulonephritis.

IgA nephropathy

Globally, IgA nephropathy (IgAN) is the most common primary glomerulonephritis that can progress to renal failure. The exact pathogenesis of IgAN is not well defined, but current biochemical and genetic data implicate overproduction of aberrantly glycosylated IgA1. These aberrant immunoglobulins are characterized by galactose deficiency of some hinge-region O-linked glycans. However, aberrant glycosylation alone is insufficient to induce renal injury: the participation of glycan-specific IgA and IgG autoantibodies that recognize the undergalactosylated IgA1 molecule is required. Glomerular deposits of immune complexes containing undergalactosylated IgA1 activate mesangial cells, leading to the local overproduction of cytokines, chemokines and complement. Emerging data indicate that mesangial-derived mediators that are released following mesangial deposition of IgA1 lead to podocyte and tubulointerstitial injury via humoral crosstalk. Patients can present with a range of signs and symptoms, from asymptomatic microscopic haematuria to macroscopic haematuria. The clinical progression varies, with 30-40% of patients reaching end-stage renal disease 20-30 years after the first clinical presentation. Currently, no IgAN-specific therapies are available and patients are managed with the aim of controlling blood pressure and maintaining renal function. However, new therapeutic approaches are being developed, building upon our ever-improving understanding of disease pathogenesis.

Recent advances in the understanding and management of IgA nephropathy

Since its first description in 1968, IgA nephropathy has remained the most common form of primary glomerulonephritis leading to chronic kidney disease in developed countries. The clinical progression varies, and consequent end-stage renal disease occurs in 30% to 40% of patients 20 to 30 years after the first clinical presentation. Current data implicate overproduction of aberrantly glycosylated IgA1 as being pivotal in the induction of renal injury. Effective and specific treatment is still lacking, and new therapeutic approaches will be developed after better understanding the disease pathogenesis.

Update on immunoglobulin a nephropathy. Part II: Clinical, diagnostic and therapeutical aspects

Immunoglobulin A nephropathy (IgAN) is characterized by different clinical manifestations and by long-term different outcomes. Major problem for the physicians is to understanding which patients are at risk of a disease evolution and to prescribe the right therapy to the right patients. Indeed, in addition to patients with a stable disease with no trend to evolution or even with a spontaneous recovery, patients with an active disease and patients with a rapidly evolving glomerulonephritis are described. Several histopathological, biological and clinical markers have been described and are currently used to a better understanding of patients at risk, to suggest the right therapy and to monitor the therapy effect and the IgAN evolution over time. The clinical markers are the most reliable and allow to divide the IgAN patients into three categories: The low risk patients, the intermediate risk patients and the high risk patients. Accordingly, the therapeutic measures range from no therapy with the only need of repeated controls, to supportive therapy eventually associated with low dose immunosuppression, to immunosuppressive treatment in the attempt to avoid the evolution to end stage renal disease. However the current evidence about the different therapies is still matter of discussion. New drugs are in the pipeline and are described. They are object of randomized controlled trials, but studies with a number of patients adequately powered and with a long follow up are needed to evaluate efficacy and safety of these new drugs.