The Pathogenesis of IgA Nephropathy: What Is New and How Does It Change Therapeutic Approaches?

Primary glomerular diseases and long-term adverse health outcomes: A nationwide cohort study

BACKGROUND

Although glomerular diseases are the third most frequent cause of end-stage kidney disease worldwide, little is known about their long-term outcomes.

METHODS

In patients with chronic kidney disease (CKD) stage 3-5 enrolled in the Swedish Renal Registry, we compared risks of hospitalization, kidney replacement therapy (KRT), major cardiovascular events (MACE), and death of the four most frequent primary glomerular diseases (IgA nephropathy [IgAN], focal segmental glomerulosclerosis [FSGS], minimal change disease [MCD], and membranous nephropathy [MN]), and patients with CKD due to the most common non-communicable diseases (control-CKD).

RESULTS

We identified 2396 patients with glomerular disease (97% biopsy-proven, 69% men, 57 years, eGFR 29 mL/min/1.73 m2, uACR 88 mg/mmol, 1524 with IgAN, 398 FSGS, 94 MCD, and 380 MN) and 37,697 controls (64% men, 74 years, eGFR 25 mL/min/1.73 m2, uACR 23 mg/mmol), mainly with diabetic nephropathy and nephroangiosclerosis. The median follow-up was 6.3 (3.3; 9.9) years. Compared with control-CKD, patients with primary glomerular diseases generally had a lower risk of hospitalization, MACE (adjusted hazard ratios [HRs] ranging from 0.44 to 0.88 depending on the etiology) and death (HRs ranging 0.45-0.76). Patients with IgAN and FSGS had a faster eGFR decline and a higher rate of KRT (HRs 1.26 [95%CI: 1.15-1.37] and 1.34 [1.15-1.57], respectively). Conversely, patients with MN and MCD had a lower KRT rate and slower eGFR decline.

CONCLUSION

Despite having a lower relative risk of hospitalization, cardiovascular events and mortality, patients with IgAN and FSGS are at higher risk of CKD progression than the most common etiologies of CKD, emphasizing the need for more stringent treatment strategies in these patients.

[IgA nephropathy]

IgA nephropathy (IgAN) is the most frequent primary form of glomerulonephritis. The origin of IgAN is only partially understood and appears to involve the occurrence of IgA1, which is normally secreted by mucous membranes, in the circulation followed by its glomerular deposition and inflammatory changes. Clinically, IgAN mostly follows an inapparent course and the disease is often only first diagnosed by kidney biopsy when kidney function disorders are already manifested. Key prognostic indicators include the extent of proteinuria and the already manifested evidence of irreversible kidney damage. Treatment includes supportive measures. The effectiveness of high-dose systemic corticosteroid treatment in European patients is uncertain and controversial due to the adverse side effects. Nefecon (encapsulated budesonide) is the first specific drug licensed for treatment of high risk IgAN patients. A number of further approaches are currently in clinical trials.

[IgA nephropathy]

IgA nephropathy (IgAN) is the most frequent primary form of glomerulonephritis. The origin of IgAN is only partially understood and appears to involve the occurrence of IgA1, which is normally secreted by mucous membranes, in the circulation followed by its glomerular deposition and inflammatory changes. Clinically, IgAN mostly follows an inapparent course and the disease is often only first diagnosed by kidney biopsy when kidney function disorders are already manifested. Key prognostic indicators include the extent of proteinuria and the already manifested evidence of irreversible kidney damage. Treatment includes supportive measures. The effectiveness of high-dose systemic corticosteroid treatment in European patients is uncertain and controversial due to the adverse side effects. Nefecon (encapsulated budesonide) is the first specific drug licensed for treatment of high risk IgAN patients. A number of further approaches are currently in clinical trials.

Mutual regulation between glycosylation and transforming growth factor-β isoforms signaling pathway

Transforming growth factor-beta (TGF-β) superfamily members orchestrate a wide breadth of biological processes. Through Sma and Mad (Smad)-related dependent or noncanonical pathways, TGF-β members involve in the occurrence and development of many diseases such as cancers, fibrosis, autoimmune diseases, cardiovascular diseases and brain diseases. Glycosylation is one kind of the most common posttranslational modifications on proteins or lipids. Abnormal protein glycosylation can lead to protein malfunction and biological process disorder, thereby causing serious diseases. Previously, researchers commonly make comprehensive systematic overviews on the roles of TGF-β signaling in a specific disease or biological process. In recent years, more and more evidences associate glycosylation modification with TGF-β signaling pathway, and we can no longer disengage and ignore the roles of glycosylation from TGF-β signaling to make investigation. In this review, we provide an overview of current findings involved in glycosylation within TGF-βs and theirs receptors, and the interaction effects between glycosylation and TGF-β subfamily signaling, concluding that there is an intricate mutual regulation between glycosylation and TGF-β signaling, hoping to present the glycosylation regulatory patterns that concealed in TGF-βs signaling pathways.

The Human Virome and Its Crosslink with Glomerulonephritis and IgA Nephropathy

The prokaryotic, viral, fungal, and parasitic microbiome exists in a highly intricate connection with the human host. In addition to eukaryotic viruses, due to the existence of various host bacteria, phages are widely spread throughout the human body. However, it is now evident that some viral community states, as opposed to others, are indicative of health and might be linked to undesirable outcomes for the human host. Members of the virome may collaborate with the human host to retain mutualistic functions in preserving human health. Evolutionary theories contend that a particular microbe's ubiquitous existence may signify a successful partnership with the host. In this Review, we present a survey of the field's work on the human virome and highlight the role of viruses in health and disease and the relationship of the virobiota with immune system control. Moreover, we will analyze virus involvement in glomerulonephritis and in IgA nephropathy, theorizing the molecular mechanisms that may be responsible for the crosslink with these renal diseases.

Efficacy and indications of tonsillectomy in patients with IgA nephropathy: a retrospective study

Background

The efficacy and indications of tonsillectomy in IgA nephropathy (IgAN) remain uncertain.

Methods

We performed a retrospective cohort study of 452 patients with primary IgAN, including 226 patients who received tonsillectomy and 226 controls selected by propensity score matching who had never undergone tonsillectomy. Study outcomes were clinical remission defined as negative hematuria and proteinuria on three consecutive visits over a 6-month period, the endpoint defined as end-stage renal disease or an irreversible 100% increase in serum creatinine from the baseline value. In addition, we further analyzed the critical level of proteinuria in the efficacy of tonsillectomy and the correlation between MEST-C score and tonsillectomy.

Results

Up to December 2019, the follow-up period lasted 46 ± 23 months (12-106 months). Kaplan-Meier and multivariate Cox regression analysis revealed that tonsillectomy was beneficial for clinical remission and renal survival. Whether proteinuria was ≤ 1 g/24h or >1 g/24h, the clinical remission and renal survival rates were greater in patients treated with tonsillectomy than without. When the pathological damage was mild or relatively severe, tonsillectomy may be beneficial to clinical remission or renal survival.

Conclusions

Tonsillectomy had a favorable effect on clinical remission and delayed renal deterioration in IgAN. In addition to patients with early stage IgAN, it may also be beneficial to IgAN patients with higher levels of proteinuria and relatively severe pathological damage.

Time-Averaged Hematuria as a Prognostic Indicator of Renal Outcome in Patients with IgA Nephropathy

We aim to investigate the association of time-averaged hematuria (TA-hematuria) with the progression of IgA nephropathy (IgAN). Based on TA-hematuria during follow-up, 152 patients with IgAN were divided into a hematuria remission group (≤28 red blood cells [RBCs]/μL) and a persistent hematuria group (>28 RBCs/μL). The persistent hematuria group had a higher percentage of patients with macroscopic hematuria, lower levels of hemoglobin and TA-serum albumin, and more severe renal pathologic lesions. The composite endpoint is defined as a doubling of the baseline SCr level (D-SCr), or the presence of ESRD. During the mean follow-up of 58.08 ± 23.51 months, 15 patients (9.9%) reached the primary outcome of ESRD and 19 patients (12.5%) reached the combined renal endpoint. Kaplan-Meier analysis showed that the persistent hematuria group had a lower renal survival rate. The persistent hematuria patients who were incorporated with proteinuria (≥1.0 g/day) and low TA-serum albumin (<40 g/L) had the worst renal outcomes. Multivariate Cox regression indicated that TA-hematuria (hazard ratio [HR] = 0.004, 95% CI: 0.001, 0.008; p = 0.010) was independently associated with the progression of IgAN. Receiver operating characteristic analysis indicated the optimal TA-hematuria cutoff value for predicting the progression of IgAN was 201.21 RBCs/μL in females and 37.25 RBCs/μL in males.

Identification of ANXA2 on epithelial cells as a new receptor for secretory IgA using immunoprecipitation and mass spectrometry

Secretory immunoglobulin A plays an important role in the protection against exogenous pathogens and antigens, but it has also been reported to have pathogenic potential. We previously found that secretory immunoglobulin A accumulated in the peripheral lungs during idiopathic pulmonary fibrosis and that transferrin receptor/CD71 was partially involved in secretory immunoglobulin A-induced inflammatory cytokine production in A549 cells. This study aimed to identify the receptor responsible for the induction of cytokine production by secretory immunoglobulin A-stimulated airway epithelial cells. To this end, immunoprecipitation followed by time-of-flight mass spectrometry and peptide mass fingerprinting were performed and Annexin A2 was detected as a novel receptor for secretory immunoglobulin A. Enzyme-linked immunosorbent assay demonstrated binding of secretory immunoglobulin A to Annexin A2, and flow cytometry showed robust expression of Annexin A2 on the surface of BEAS-2B cells, A549 cells, and normal human bronchial/tracheal epithelial cells. Experiments in A549 cells using Annexin A2 small interfering RNA and neutralizing antibodies suggested that Annexin A2 was partially involved in the production of interleukin-8/CXCL8 and C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 induced by secretory immunoglobulin A. Immunohistochemistry using lung sections revealed clear expression of Annexin A2 on airway epithelial cells, although the staining remained equivalent in idiopathic pulmonary fibrosis, asthma, and healthy control lungs. In conclusion, we identified that Annexin A2 expressed in airway epithelial cells is a novel receptor for secretory immunoglobulin A, which is involved in cytokine synthesis.

A multicenter, randomized, open-label, comparative, phase IV study to evaluate the efficacy and safety of combined treatment with mycophenolate mofetil and corticosteroids in advanced immunoglobulin A nephropathy

Background

It remains unclear whether immunosuppressive agents are effective in patients with immunoglobulin A nephropathy (IgAN). We investigated the efficacy of a mycophenolate mofetil (MMF) and corticosteroid combination therapy in patients with advanced IgAN.

Methods

We conducted a multicenter, randomized, placebo-controlled, parallel-group study of 48 weeks administration of MMF and corticosteroids in biopsy-proven advanced IgAN patients with estimated glomerular filtration rate (eGFR) of 20–50 mL/min/1.73 m² and urine protein-to-creatinine ratio (UPCR) of >0.75 g/day. The primary outcome was complete (UPCR < 0.3 g/day) or partial (>50% reduction of UPCR compared to baseline) remission at 48 weeks.

Results

Among the 48 randomized patients, the percentage that achieved complete or partial remission was greater in thecombination therapy group than in the control group (4.2% vs. 0% and 29.1% vs. 5.0%, respectively). Compared with the combination therapy group, eGFR in the control group decreased significantly from week 36 onward, resulting in a final adjusted mean change of –4.39 ± 1.22 mL/min/1.73 m² (p = 0.002). The adjusted mean changes after 48 weeks were 0.62 ± 1.30 and –5.11 ± 1.30 mL/min/1.73 m² (p = 0.005) in the treatment and control groups, respectively. The UPCR was significantly different between the two groups; the adjusted mean difference was –0.47 ± 0.17 mg/mgCr and 0.07 ± 0.17 mg/mgCr in the treatment and control group, respectively (p = 0.04). Overall adverse events did not differ between the groups.

Conclusion

In advanced IgAN patients with a high risk for disease progression, combined MMF and corticosteroid therapy appears to be beneficial in reducing proteinuria and preserving renal function.

Aberrantly Glycosylated IgA1 in IgA Nephropathy: What We Know and What We Don't Know

IgA nephropathy (IgAN), the most common primary glomerular disease worldwide, is characterized by glomerular deposition of IgA1-containing immune complexes. The IgA1 hinge region (HR) has up to six clustered O-glycans consisting of Ser/Thr-linked N-acetylgalactosamine usually with β1,3-linked galactose and variable sialylation. Circulating levels of IgA1 with abnormally O-glycosylated HR, termed galactose-deficient IgA1 (Gd-IgA1), are increased in patients with IgAN. Current evidence suggests that IgAN is induced by multiple sequential pathogenic steps, and production of aberrantly glycosylated IgA1 is considered the initial step. Thus, the mechanisms of biosynthesis of aberrantly glycosylated IgA1 and the involvement of aberrant glycoforms of IgA1 in disease development have been studied. Furthermore, Gd-IgA1 represents an attractive biomarker for IgAN, and its clinical significance is still being evaluated. To elucidate the pathogenesis of IgAN, it is important to deconvolute the biosynthetic origins of Gd-IgA1 and characterize the pathogenic IgA1 HR O-glycoform(s), including the glycan structures and their sites of attachment. These efforts will likely lead to development of new biomarkers. Here, we review the IgA1 HR O-glycosylation in general and the role of aberrantly glycosylated IgA1 in the pathogenesis of IgAN in particular.

Precision medicine in immunoglobulin A nephropathy: still a journey ahead

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide and since its first description extensive research has identified a number of key central pathogenetic contributors, including genetic, immunological and environmental factors. Along with its multifaceted pathophysiology, the clinical presentation of IgAN varies, ranging from mild forms with only minor urinary findings and preserved renal function to cases that rapidly progress to end-stage renal disease. Because of this, early identification of patients at risk for a progressive course is urgently needed. The search for valid and easily accessible biomarkers showed urinary Dickkopf-3 as a promising candidate to predict the course of kidney function. In addition, a recently established IgAN risk prediction tool derived from an international cohort of IgAN patients allows estimation of the risk of a 50% loss of kidney function over several years upon diagnosis. This might serve as a significant tool to individually predict the course of renal function by combining biometric, clinical, histological and treatment information at the time of diagnosis. Today there is no doubt that a comprehensive supportive treatment regimen is the main pillar for all IgAN patients. The value of an additional immunosuppressive treatment in IgAN patients at risk for disease progression is less clear. Early risk stratification and individualized therapies would be desirable for IgAN patients to facilitate the choice of treatment strategies, which is still a matter of ongoing discussion.

Immunofluorescence deposits in the mesangial area and glomerular capillary loops did not affect the prognosis of immunoglobulin a nephropathy except C1q:a single-center retrospective study

Background

Immunoglobulin A nephropathy (IgAN) is identified as mesangial IgA deposition and is usually accompanied by other immunofluorescence deposits. The impact of immunofluorescent features in IgAN patients, however, remains unclear.

Methods

Baseline clinicopathologic parameters and renal outcomes of 337 patients diagnosed with IgAN between January 2009 and December 2015 were analyzed. We then categorized these patients into four groups: without immunofluorescence deposits, mesangial-only, mesangial and glomerular capillary loops (GCLs), and GCLs-only. The study endpoint was end-stage kidney disease (ESKD) or a ≥ 50% decline in the estimated glomerular filtration rate (eGFR). Kaplan–Meier and Cox regression analyses were performed to calculate renal survival.

Results

Of the 337 IgAN patients, women comprised 57.0%. Compared to patients with IgA deposition in the mesangial-only group, patients with IgA deposition in the mesangial +GCLs group were much heavier, and exhibited higher systolic blood pressure, lower serum IgG levels, and heavier proteinuria (all P < 0.05). Patients with IgG deposition in the mesangial +GCLs group presented with higher levels of cholesterol, heavier proteinuria than IgG deposition in the mesangial-only group (both P < 0.05). Compared with the mesangial-only group exhibiting C3 deposits, patients in the mesangial +GCLs group with C3 deposition had a higher systolic blood pressure (P = 0.028). A total of 38 patients (11.3%) continued to the study endpoint after a median follow-up time of 63.5 months (range,49.8–81.4). Kaplan–Meier analysis and Cox regression analysis showed that C1q deposition in the mesangial +GCLs group predicted a poor renal prognosis.

Conclusions

IgA and IgG deposits in the mesangial region and GCLs were associated with more unfavorable clinical and histopathologic findings in IgAN patients. C1q deposition in the mesangial region and GCLs predicted a poor renal prognosis. However, the impact of the pattern of immunofluorescence deposits on renal outcomes remains to be proven by further investigation.

Circulating inflammation-related factors are correlated with systemic redox status in IgA nephropathy; a case-control study

BACKGROUND

IgA nephropathy (IGAN) is characterized by oxidative stress and inflammation. In the present study, we explored the relationship of redox status vs. that of circulating inflammation-related factors with other biomarkers in patients with IGAN.

METHODS

This is a case-control study comparing patients with IGAN (Stage 1-4) to healthy controls. Forty patients and 40 controls were matched for age and sex. Two circulating dynamic redox parameters were analysed: oxidized free cysteine (Cys) and nitrate. Thirty-seven inflammation-related factors were measured in serum.

RESULTS

The patients had elevated levels of oxidized free Cys and nitrate, indicating the presence of oxidative stress. Nine circulating inflammation-related factors were higher in the serum of patients than in that of controls. The most important factors were APRIL, MMP-3, osteopontin, TNFR1 and TWEAK. Inflammation-related factors were positively correlated with oxidized free Cys, nitrate, creatinine and parathyroid hormone (PTH) in the patients. The correlation coefficients of Latent Inflammatory Factor vs. oxidized free Cys and nitrate were r = 0.43 (p = 0.007) and r = 0.51 (p = 0.001), respectively. This finding persisted after adjusting for the glomerular filtration rate.

CONCLUSIONS

Patients with IGAN had disturbed redox status. Several circulating inflammation-related factors were elevated, suggesting activation of the non-canonical NF-kB pathway. There was a positive relationship between systemic redox status and the level of inflammation-related factors, partially independent of GFR. The present findings raise the question of whether circulating oxidized free Cys and/or nitrate may be employed as prognostic biomarkers for IGAN in the future.

Eosinophilic fasciitis associated with generalized morphea and IgA nephropathy

Eosinophilic fasciitis (EF) is a rare connective tissue disease characterized by increased peripheral blood eosinophils and diffuse fasciitis, generalized morphea (GM) is a subtype of localized scleroderma, and IgA nephropathy is a chronic glomerulonephritis caused by abnormal deposition of IgA in the mesangial area of the glomeruli. We describe a 49-year-old male patient with hard skin, cutaneous hyperpigmentation, and proteinuria. The patient had suffered from a long disease course of hard skin, while urine protein was newly detected. Finally, the clinical presentation and physical examination, limb MRI, skin biopsy, and renal biopsy confirmed the diagnosis of eosinophilic fasciitis associated with generalized morphea and IgA nephropathy. This case is the first report of EF associated with GM and IgA nephropathy.

The Role of Immune Modulation in Pathogenesis of IgA Nephropathy

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis worldwide, with diverse clinical manifestations characterized by recurrent gross hematuria or microscopic hematuria, and pathological changes featuring poorly O-galactosylated IgA1 deposition in the glomerular mesangium. Pathogenesis has always been the focus of IgAN studies. After 50 years of research, most scholars agree that IgAN is a group of clinicopathological syndromes with certain common immunopathological characteristics, and multiple mechanisms are involved in its pathogenesis, including immunology, genetics, and environmental or nutritional factors. However, the precise pathogenetic mechanisms have not been fully determined. One hypothesis about the pathogenesis of IgAN suggests that immunological factors are engaged in all aspects of IgAN development and play a critical role. A variety of immune cells (e.g., dendritic cells, NK cells, macrophages, T-lymphocyte subsets, and B-lymphocytes, etc.) and molecules (e.g., IgA receptors, Toll-like receptors, complements, etc.) in innate and adaptive immunity are involved in the pathogenesis of IgAN. Moreover, the abnormality of mucosal immune regulation is the core of IgAN immunopathogenesis. The roles of tonsil immunity or intestinal mucosal immunity, which have received more attention in recent years, are supported by mounting evidence. In this review, we will explore the latest research insights on the role of immune modulation in the pathogenesis of IgAN. With a better understanding of immunopathogenesis of IgAN, emerging therapies will soon become realized.

Relationship between serum C3/C4 ratio and prognosis of immunoglobulin A nephropathy based on propensity score matching

Background

Aberrant activation of the complement system plays an important role in the pathogenesis and development of immunoglobulin A nephropathy (IgAN). The relationship between serum complement and the clinical-histopathological features and outcomes of IgAN is controversial. This retrospective study aimed to examine the relationship between the complement 3/4 (C3/C4) ratio and the clinicopathologic changes and prognosis of patients with IgAN.

Methods

A total of 397 patients with primary IgAN from January 2007 to December 2012 at the Chinese People's Liberation Army General Hospital were included in this study. The correlation test and Chi-square test or one-way analysis of variance test were performed to evaluate the relationship between the C3/C4 ratio and other clinical-pathological factors. Propensity score matching and a multivariate Cox regression model were used to calculate the risk factors of renal outcome.

Results

The median follow-up period was 75 months. During the follow-up period, 62 patients (15.6%) developed into the end-stage renal disease (ESRD). The C3/C4 ratio at baseline was associated with the level of serum creatinine (SCr), 24 h urinary protein excretion (24 h Upre), global glomerular sclerosis, and tubulointerstitial lesion. The level of SCr and 24 h Upre and the degree of chronic kidney injury were statistically different among groups defined by different C3/C4 ratio levels. The survival rates of patients among groups with different C3/C4 ratio levels were different. After propensity score matching, eighty-eight pairs of patients were successfully matched, and the C3/C4 ratio was an influencing factor for the patients’ outcome (hazard ratio 0.587, 95% confidence interval 0.329–0.880). Patients with a C3/C4 ratio <3.6 had a poorer outcome compared with the others (P = 0.002).

Conclusions

IgAN patients with decreased C3/C4 ratio displayed significantly more severe clinical symptoms and chronic renal injury than patients with higher ratios. A low C3/C4 ratio could be a risk factor for patients developing to ESRD.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Changes in the clinical presentation of immunoglobulin A nephropathy: data from the Spanish Registry of Glomerulonephritis

Background

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis in the world, but there is little epidemiological data about possible changes in its presentation over the years. Available information about the influence of age on the form of clinical presentation is also scarce.

Methods

The aim of the study was to analyse all renal biopsies performed between 1994 and 2013 and recorded in the Spanish Registry of Glomerulonephritis with a histological diagnosis of IgAN. The study was divided into five 4-year periods (1994-97, 1998-2001, 2002-05, 2006-09 and 2010-13) and patients were divided into four age groups: ≤16, 17-44, 45-64 and ≥65 years.

Results

From 20.974 renal biopsies recorded, 2961 (14.1%) corresponded to IgAN. The prevalence of IgAN remained stable, but a significant increase in age [from 37.6 (SD 17.7) in 1994-97 to 44.9 (SD 16.8) years in 2010-13; P = 0.001] and worse renal function at presentation [from serum creatinine (SCr) 1.9 (SD 1.9) in 1994-97 to 2.3 (SD 2.1) mg/dL in 2010-13; P = 0.001] were observed over the years. Nephrotic-range proteinuria and acute kidney injury (AKI) as forms of presentation were significantly more common among patients ≥65 years (17.7% and 43.2%, respectively) as compared with the other age groups [≤16 (11.4% and 13.1%, respectively), 17-44 (13.1% and 13%, respectively) and 45-64 (12.1% and 21.3%, respectively)]. Blood pressure, SCr and proteinuria were also significantly higher at presentation among elderly patients.

Conclusions

Although the prevalence of IgAN in Spain has remained stable over the years, patients are significantly older and present with significantly worse renal function in the last years. The incidence of nephrotic-range proteinuria (17.7%) and AKI (43.2%) as forms of presentation is remarkable among patients ≥65 years of age.

The role of complement in IgA nephropathy

IgA nephropathy (IgAN) is common and often progresses to end stage renal disease. IgAN encompasses a wide range of histology and clinical features. IgAN pathogenesis is incompletely understood; the current multi-hit hypothesis of IgAN pathogenesis does not explain the range of glomerular inflammation and renal injury associated with mesangial IgA deposition. Although associations between IgAN and glomerular and circulating markers of complement activation are established, the mechanism of complement activation and contribution to glomerular inflammation and injury are not defined. Recent identification of specific complement pathways and proteins in severe IgAN cases had advanced our understanding of complement in IgAN pathogenesis. In particular, a growing body of evidence implicates the complement factor H related proteins 1 and 5 and lectin pathway as pathogenic in a subset of patients with severe disease. These data suggest complement deregulation and activity may be dominant drivers of renal injury in IgAN. Thereby, markers of complement activation may identify IgAN patients likely to progress to significant renal impairment and complement inhibition may emerge as an effective method of preventing and reducing glomerular injury in IgAN.

IgA1 isolated from Henoch-Schönlein purpura children promotes proliferation of human mesangial cells in vitro

Previous studies show that the proliferation of human mesangial cells (HMCs) played a significant part in the pathogenesis of Henoch-Schönlein purpura nephritis (HSPN). The aim of this study was to explore the proliferation of HMCs induced by IgA1 isolated from the sera of HSP patients. HMCs were cultured in three different types of media, including IgA1 from patients with HSP (HSP IgA1 group), healthy children (healthy IgA1 group) and medium (control group). The proliferation of HMCs incubated with IgA1 was determined by cell counting kit-8 assay and bromodeoxyuridine incorporation. The expression of ERK1/2 and phosphatidylinositol 3 kinase/protein kinase B/mammalian targets of the rapamycin (PI3K/AKt/mTOR) signals and transferrin receptor (TfR/CD71) was detected with the methods of immunoblotting. The results indicated that the proliferation of HMCs significantly increased in the HSP IgA1 group compared with that in the control group or the healthy IgA1 group (P < 0.001). Moreover, we found that IgA1 isolated from HSP patients activated ERK and PI3K/AKt/mTOR signals, and markedly increased TfR/CD71 expression in HMCs. These effects induced by IgA1 isolated from patients with HSP were inhibited by human TfR polyclonal antibody (hTfR pAb) and soluble human transferrin receptor (sTfR), indicating that IgA1-induced HMC proliferation and ERK1/2 and PI3K/AKt/mTOR activation were dependent on TfR/CD71 engagement. Altogether, these data suggested that TfR/CD71 overexpression and ERK1/2 and PI3K/AKt/mTOR activation were engaged in HMC proliferation induced by IgA1 from HSP patients, which might be related to the mesangial injury of HSPN.

Serum C3/C4 ratio is a novel predictor of renal prognosis in patients with IgA nephropathy: a retrospective study

IgA nephropathy (IgAN) is an autoimmune disease associated with complement activation. It is unclear whether the ratio of serum C3 and C4 concentrations (C3/C4 ratio) can predict renal outcomes in IgAN patients. A total of 1503 patients diagnosed with IgAN via renal biopsy were recorded in this study. Poor renal outcomes were defined as > 50% decrease in the baseline estimated glomerular filtration rate (eGFR) or development of end-stage renal disease (ESRD) during follow-up. In total, 712 patients meeting the exclusion/inclusion criteria were selected, and the mean follow-up period was 40.6 (12.34) months. Patients with decreased C3/C4 ratios displayed significantly more severe clinical characteristics and renal pathological features and a higher proportion of poor renal outcomes and ESRD. The optimal multivariate Cox regression models identified the C3/C4 ratio (hazard ratio (HR) 0.63, 95% CI 0.5-0.9), serum uric acid (HR 1.58, 95% CI 1.2-2.2), serum creatinine (HR 1.3, 95% CI 1.1-1.6), systolic blood pressure (HR 1.57, 95% CI 1.2-2.0) and T score (relative to T0, T1: HR 1.96, 95% CI 1.1-3.7, T2: HR 3.03, 95% CI 1.6-5.9) as strong predictors of poor renal outcomes. Subgroup analysis showed that patients with low C3/C4 ratios benefited from glucocorticoids or other immunosuppressive agents (hazard ratio 0.30 and 0.18, 95% CI 0.13-0.72 and 0.07-0.46, respectively). Serum C3/C4 ratios may be an independent novel predictor of renal outcomes in IgAN patients. Decreased C3/C4 ratios suggest poor renal outcomes and the potential to benefit from aggressive immunosuppressive therapies.

Steroid pulse therapy transiently destroys the discriminative histological structure of tonsils in IgA nephropathy: Tonsillectomy should be performed before or just after steroid pulse therapy

OBJECTIVE

Tonsillectomy combined with steroid-pulse therapy is a widely accepted method for the treatment of IgA nephropathy (IgAN) in Japan. However, the indication of tonsillectomy for IgAN is still controversial, and the timing of tonsillectomy is not clearly defined for the protocol of this therapy. Based on the results of a randomized control trial in Japan, the Evidence-Based Clinical Practice Guidelines for IgA nephropathy 2014 (edited in Japan) recommended tonsillectomy combined with steroid-pulse therapy for Grade C1. However, this is not widely accepted worldwide. To clarify the validity and timing of tonsillectomy, we evaluated how the three-consecutive steroid-pulse therapy method affects the tonsil tissues of IgAN patients.

METHODS

We examined tonsil specimens from 35 IgAN patients and 8 chronic tonsillitis patients. We compared the proportion of follicular area to total tonsillar area and the number of germinal centers between each group on hematoxylin and eosin stained pathological specimens to clarify the histopathological characteristics of tonsils from IgAN patients. Based on these findings, we examined the tonsils of patients after three-consecutive steroid-pulse therapy treatments (n=34) to determine the influence of this therapy on the tonsil tissues of IgAN patients. Moreover, we observed chronological changes in tonsil tissues after steroid-pulse therapy.

RESULTS

The extrafollicular area was enlarged in IgAN patients before steroid-pulse therapy compared with chronic tonsillitis patients. Just after steroid-pulse therapy, the follicles became very small with blurry outlines, and the number of germinal centers was remarkably decreased. With a gradual decrease in oral prednisolone, the tonsil tissue structure was gradually restored.

CONCLUSION

Tonsillectomy combined with steroid-pulse therapy is considered a reasonable treatment for IgAN. Steroid-pulse therapy-induced histological changes in tonsils were transient, indicating tonsillectomy should be performed before or just after steroid-pulse therapy.

Defective activation of the MAPK/ERK pathway, leading to PARP1 and DNMT1 dysregulation, is a common defect in IgA nephropathy and Henoch-Schönlein purpura

Studies on IgA nephropathy (IgAN) have identified, through GWAS, linkage analysis, and pathway scanning, molecular defects in familial and sporadic IgAN patients. In our previous study, we identified a novel variant in the SPRY2 gene that segregates with the disease in one large family. The functional characterization of this variant led us to discover that the MAPK/ERK pathway was defective not only in this family, but also in two sporadic IgAN patients wild type for SPRY2. In the present study, we have deepened the molecular analysis of the MAPK/ERK pathway and extended our evaluation to a larger cohort of sporadic patients and to one additional family. We found that the ERK pathway is defective in IgAN patients and in patients affected by another IgA-mediated disorder, Henoch-Schönlein purpura (HSP). Furthermore, we found that two other proteins, PARP1 and DNMT1, respectively involved in DNA repair and in antibody class switching and methylation maintenance duties, were critically downregulated in IgAN and HSP patients. This study opens up the possibility that defective ERK activation, in some patients, leads to PARP1 and DNMT1 downregulation suggesting that IgAN could be the consequence of a dysregulated epigenetic maintenance leading to the upregulation of several genes. In particular, PARP1 could be used as a potential biomarker for the disease.

Celiac Disease and Risk of Henoch-Schonlein Purpura: Population-based Cohort Study

BACKGROUND AND AIMS

A recent study found a 10-fold increased risk of celiac disease (CD) in individuals with Henoch-Schonlein purpura (HSP), but the confidence interval (CI) was wide.

METHODS

The retrospective cohort study of all patients with CD in Sweden, diagnosed through small intestinal biopsy from 1969 to 2008 (n=29,077). Each individual with CD was matched to up to 5 controls (n=144,433). Data on study participants were linked to diagnostic codes for HSP in the National Patient Registry. Through Cox regression we estimated hazard ratios for CD and later HSP. Through logistic regression we calculated odds ratios for HSP preceding CD.

RESULTS

During follow-up 19 individuals with CD and 99 controls developed HSP. This corresponded to a hazard ratio of 0.96 (95% CI, 0.59-1.56). Looking backward, we found no increased risk of earlier HSP in patients with CD (odds ratio=1.02; 95% CI, 0.60-1.72).

CONCLUSIONS

In this study of more than 29,000 patients with CD, we found no increased risk of HSP before or after CD.

1 H NMR-based metabolomics study for identifying urinary biomarkers and perturbed metabolic pathways associated with severity of IgA nephropathy: a pilot study

The severity of IgA nephropathy (IgAN), the most common primary glomerulonephritis, is judged on the basis of histologic and clinical features. A limited number of studies have considered molecular signature of IgAN for this issue, and no reliable biomarkers have been presented non-invasively for use in patient evaluations. This study aims to identify metabolite markers excreted in the urine and impaired pathways that are associated with a known marker of severity (proteinuria) to predict mild and severe stages of IgAN. Urine samples were analysed using nuclear magnetic resonance from biopsy-proven IgAN patients at mild and severe stages. Multivariate statistical analysis and pathway analysis were performed. The most changed metabolites were acetoacetate, hypotaurine, homocysteine, L-kynurenine and phenylalanine. Nine metabolites were positively correlated with proteinuria, including mesaconic acid, trans-cinnamic acid, fumaric acid, 5-thymidylic acid, anthranilic acid, indole, deoxyguanosine triphosphate, 13-cis-retinoic acid and nicotinamide riboside, while three metabolites were negatively correlated with proteinuria including acetoacetate, hypotaurine and hexanal. 'Phenylalanine metabolism' was the most significant pathway which was impaired in severe stage in comparison to mild stage of IgAN. This study indicates that nuclear magnetic resonance is a versatile technique that is capable of detecting metabolite biomarkers in combination with advanced multivariate statistical analysis. Copyright © 2017 John Wiley & Sons, Ltd.

Circulating CD89-IgA complex does not predict deterioration of kidney function in Korean patients with IgA nephropathy

Background:

Soluble CD89 (sCD89)-IgA complex plays a key role in the pathogenesis of IgA nephropathy (IgAN). However, there is a lack of evidence supporting this complex as a good biomarker for disease progression. This study aimed to evaluate the usefulness of sCD89-IgA complex for risk stratification of IgAN.

Methods:

A total of 326 patients with biopsy-proven IgAN were included. sCD89-IgA complex was measured by sandwich-enzyme-linked immunosorbent assay. The study endpoints were a 30% decline in estimated glomerular filtration rate (eGFR).

Results:

sCD89-IgA complex levels were inversely and weakly associated with eGFR at the time of biopsy (r=−0.12, p=0.03). However, the significance between the two factors was lost in the multivariate linear regression after adjustment of clinical factors (β=0.35, p=0.75). In a multivariate Cox model, the highest (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.35–1.61; p=0.45) and middle (HR, 0.93; 95% CI, 0.46–1.89; p=0.84) tertiles of sCD89-IgA complex levels were not associated with an increased risk of developing a 30% decrease in eGFR. Furthermore, the decline rates in eGFR did not differ between groups and C-statistics revealed that the sCD89-IgA complex were not superior to clinical factors in predicting disease progression.

Conclusions:

This study found no association between sCD89-IgA complex levels and disease progression in IgAN. Although sCD89 can contribute to the formation of immune complexes, our findings suggest that the sCD89-IgA level is not a good predictor of adverse outcomes and has limited clinical utility as a biomarker for risk stratification in IgAN.

Differential expression of urinary exosomal microRNAs in IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common type of primary glomerulonephritis in the world. Reliable biomarkers are required for the non-invasive diagnosis and monitoring of IgAN. This study aims to investigate the difference in urinary exosomal microRNA (miRNA) expression profiles between patients with IgA nephropathy (IgAN) and healthy controls, which may provide clues to identify novel potential non-invasive miRNA biomarkers for renal diseases.

METHODS

Urine samples were collected from eighteen healthy controls and eighteen patients with IgAN. Differential centrifugation was performed to isolate exosomes from urine samples. High-throughput sequencing and real-time quantitative polymerase chain reaction (RT-qPCR) were sequentially used to screen and further validate miRNA expression profiles in urinary exosomes of patients with IgAN in two independent cohorts.

RESULTS

Urinary exosomes were successfully isolated to obtain exosomal miRNAs. MiR-215-5p and miR-378i were significantly upregulated in urinary exosomes of patients with IgAN compared with healthy controls (P<.01), while miR-29c and miR-205-5p were significantly downregulated (P<.05). MiR-215-5p, miR-378i, miR-365b-3p and miR-135b-5p were found to have altered expression in patients with IgAN from validation cohorts, which was consistent with the high-throughput sequencing analysis.

CONCLUSION

This study suggests that there is a significant difference in urinary exosomal miRNA profiles between patients with IgAN and healthy controls. These exosomal miRNAs, such as miR-29c, miR-146a and miR-205 may potentially serve as novel non-invasive biomarkers for IgAN.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

Efficacy of Leflunomide, Telmisartan, and Clopidogrel for Immunoglobulin A Nephropathy: A Randomized Controlled Trial

Background:

The efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for immunoglobulin A nephropathy (IgAN) are unclear. This study was designed to evaluate the efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for IgAN.

Methods:

It is a multicenter, prospective, double-dummy randomized controlled trial. Primary IgAN patients were recruited in 13 renal units across Beijing, China, from July 2010 to June 2012. After a 4-week telmisartan (80 mg/d) wash-in, 400 patients continuing on 80 mg/d telmisartan were randomly assigned to additionally receive placebo (Group A), 50 mg/d clopidogrel (Group B), 20 mg/d leflunomide (Group C), or 50 mg/d clopidogrel and 20 mg/d leflunomide (Group D). The 24-week intervention was completed by 360 patients. The primary endpoint was change in 24-h proteinuria at 24 weeks. A linear mixed-effect model was used to analyze the changes at 4, 12, and 24 weeks. Generalized estimating equations were used to evaluate changes in hematuria grade. This trial was registered at the Chinese Clinical Trial Registry.

Results:

The effects of telmisartan combined with leflunomide on changes in proteinuria (0.36 [95% confidence interval (CI) 0.18–0.55] g/d, P < 0.001), in serum uric acid (76.96 [95% CI 57.44–96.49] μmol/L, P < 0.001), in serum creatinine (9.49 [95% CI 6.54–12.44] μmol/L, P < 0.001), and in estimated glomerular filtration rate (−6.72 [95% CI −9.46 to −3.98] ml∙min⁻¹∙1.73 m⁻², P < 0.001) were statistically significant, whereas they were not statistically significant on changes in systolic and diastolic blood pressure and weight (P > 0.05). Telmisartan combined with clopidogrel had no statistical effect on any outcome, and there was no interaction between the interventions. No obvious adverse reactions were observed.

Conclusions:

Telmisartan combined with leflunomide, not clopidogrel, is safe and effective for decreasing proteinuria in certain IgAN patients.

Trial Registration:

chictr.org.cn, ChiCTR-TRC-10000776; http://www.chictr.org.cn/showproj.aspx?proj=8760.

Evaluation of TGF-β1 and MCP-1 expression and tubulointerstitial fibrosis in children with Henoch-Schönlein purpura nephritis and IgA nephropathy: A clinical correlation

OBJECTIVES:

Henoch-Schönlein purpura nephritis and immunoglobulin A nephropathy are two diseases with similar clinical presentations but very different prognoses. Transforming growth factor β1 and monocyte chemoattractant protein-1 have been associated with the development of tissue fibrosis. We examined the development of tubulointerstitial fibrosis and its relationship with Transforming growth factor β1 and monocyte chemoattractant protein-1 expression in these patients.

METHODS:

Renal tissue samples were collected by renal biopsy from 50 children with Henoch-Schönlein purpura nephritis and 50 children with immunoglobulin A nephropathy. Hematoxylin and eosin and Masson's trichrome-stained tissues were examined using light microscopy. Tubulointerstitial fibrosis was graded using the method described by Bohle et al. (1). The immunohistochemical detection of Transforming growth factor β1 and monocyte chemoattractant protein-1 expression was correlated with the tubulointerstitial fibrosis grade. Clinical Trial registration number: ZJCH-2012-0105.

RESULTS:

Transforming growth factor β1 and monocyte chemoattractant protein-1 expression in the renal tissues was significantly greater in the patients with immunoglobulin A nephropathy than in the patients with Henoch-Schönlein purpura nephritis (both p<0.001). The immunoglobulin A nephropathy patients had a higher tubulointerstitial fibrosis grade than the Henoch-Schönlein purpura nephritis patients (p<0.001). The tubulointerstitial fibrosis grade was in accordance with the Transforming growth factor β1 and monocyte chemoattractant protein-1 expression levels in both diseases (both p<0.001).

CONCLUSION:

Transforming growth factor β1 and monocyte chemoattractant protein-1 expression was associated with the development of immunoglobulin A nephropathy and Henoch-Schönlein purpura nephritis. Further studies are needed to better evaluate this association.

Immunosuppression in IgA nephropathy: how certain are we?

The optimal role of immunosuppressive therapy in the treatment of IgA nephropathy is controversial. Results of a recently completed randomized controlled trial provide strong support for comprehensive supportive care rather than immunosuppressive therapy in patients at high risk for progression.

TGF-β1 mimics the effect of IL-4 on the glycosylation of IgA1 by downregulating core 1 β1, 3-galactosyltransferase and Cosmc

The aberrant glycosylation of IgA1 is pivotal in the pathogenesis of IgA nephropathy (IgAN). The aim of the present study was to investigate the effect of transforming growth factor‑β1 (TGF‑β1) on the glycosylation of IgA1 and the associated mechanism. The mRNA levels of core1 β1, 3-galactosyltransferase (C1GalT1) and its molecular chaperone, Cosmc, were analyzed, as was the subsequent O-glycosylation of IgA1, in a human B‑cell line stimulated with TGF‑β1. The IgA1‑positive human B‑cell line was cultured with different concentrations of recombinant human TGF‑β1 (5, 10, 15 and 30 ng/ml). The production and glycosylation of IgA1 were assayed using sandwich ELISA and enzyme‑linked lectin binding assays, respectively, and the mRNA levels of C1GalT1 and Cosmc were quantified using reverse transcription‑quantitative polymerase chain reaction analysis. The results showed that the production of IgA1 was stimulated by low concentrations of TGF‑β1 (5 or 10 ng/ml) and was suppressed by high concentrations (15 or 30 ng/ml). The terminal glycosylation of secreted IgA1 was altered in response to TGF‑β1. TGF‑β1 stimulation significantly decreased the mRNA levels of C1GalT1 and Cosmc. TGF‑β1 may be key in controlling the glycosylation of IgA1, in part via the downregulation of C1GalT1 and Cosmc.

[Glomerulonephritides]

Many forms of glomerulonephritis, even the more common types belong to the so-called rare diseases; however, they are very important, for example with respect to health economics as they often affect young people. An example is immunoglobulin A (IgA) nephropathy, which is the most common cause of end stage renal disease in young adults. This review summarizes the current knowledge on the pathogenesis, clinical presentation and therapy of the most common European types of glomerulonephritis with a special focus on the most recently acquired knowledge on IgA nephropathy, membranous glomerulonephritis, minimal change nephropathy and focal segmental glomerulosclerosis (FSGS).

Glomerular IgG deposition predicts renal outcome in patients with IgA nephropathy

Glomerular IgG deposition is frequently observed in patients with IgA nephropathy. However, the association between glomerular IgG deposition and progression of IgA nephropathy is uncertain. Six hundred and twenty-seven patients with biopsy-proven IgA nephropathy were recruited. Histological variables of the Oxford classification (Oxford-MEST) and the presence of glomerular IgG deposits were assessed. Renal progression defined as end-stage renal disease or 50% reduction in estimated glomerular filtration rate was analyzed using Kaplan-Meier methods and Cox regression analysis. Of the study population, 200 patients (31.9%) had glomerular IgG deposition on immunofluorescence staining. During a mean follow-up of 56.8±37.5 months, the rate of renal progression was significantly higher in the IgA nephropathy patients with glomerular IgG deposition compared with the IgA nephropathy patients without glomerular IgG deposition (39.8 vs 12.3 per 1000 patient-years; P<0.001). Of patients with IgG deposition, 178 (28.3%), 20 (3.2%), and 2 (0.3%) patients had mild, moderate, and marked glomerular IgG deposits, receptively. Kaplan-Meier analysis revealed that cumulative renal survival was significantly lower in IgA nephropathy patients with the higher intensity of glomerular IgG deposits (P<0.001). In addition, Cox regression analysis revealed that moderate and marked glomerular IgG deposits significantly predicted renal outcome independent of Oxford-MEST and clinical variables (HR, 2.97; 95% CI, 1.01-8.77; P=0.04). This study showed that that glomerular IgG deposition was independently associated with poor renal outcome in patient with IgA nephropathy.

[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.

Urinary myeloid IgA Fc alpha receptor (CD89) and transglutaminase-2 as new biomarkers for active IgA nephropathy and henoch-Schönlein purpura nephritis

BACKGROUND

IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephritis (HSPN) are glomerular diseases that share a common and central pathogenic mechanism. The formation of immune complexes containing IgA1, myeloid IgA Fc alpha receptor (FcαRI/CD89) and transglutaminase-2 (TG2) is observed in both conditions. Therefore, urinary CD89 and TG2 could be potential biomarkers to identify active IgAN/HSPN.

METHODS

In this multicenter study, 160 patients with IgAN or HSPN were enrolled. Urinary concentrations of CD89 and TG2, as well as some other biochemical parameters, were measured.

RESULTS

Urinary CD89 and TG2 were lower in patients with active IgAN/HSPN compared to IgAN/HSPN patients in complete remission (P < 0.001). The CD89xTG2 formula had a high ability to discriminate active from inactive IgAN/HSPN in both situations: CD89xTG2/proteinuria ratio (AUC: 0.84, P < 0.001, sensitivity: 76%, specificity: 74%) and CD89xTG2/urinary creatinine ratio (AUC: 0.82, P < 0.001, sensitivity: 75%, specificity: 74%). Significant correlations between urinary CD89 and TG2 (r = 0.711, P < 0.001), proteinuria and urinary CD89 (r = - 0.585, P < 0.001), and proteinuria and urinary TG2 (r = - 0.620, P < 0.001) were observed.

CONCLUSIONS

Determination of CD89 and TG2 in urine samples can be useful to identify patients with active IgAN/HSPN.

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 and infections

In this paper we concentrate on the role of infections in IgA nephropathy both from a pathogenetic and clinic point of view. The current hypotheses as regards the role of infections in the pathogenesis of IgA nephropathy are: (a) role of particular pathogens, (b) chronic exposure to mucosal infections, (c) abnormal handling of commensal microbes (gut microbiota). We also focus on particular infections reported in association with classic IgA nephropathy (HIV, malaria, Chlamydia, Lyme disease), as well as on IgA dominant-infection-associated glomerulonephritis. This is a unique form of glomerulonephritis, where IgA deposition is dominant. It is mostly recognized in old, diabetic patients and in association with staphylococcal infection.

Intensive Supportive Care plus Immunosuppression in IgA Nephropathy

BACKGROUND

The outcomes of immunosuppressive therapy, when added to supportive care, in patients with IgA nephropathy are uncertain.

METHODS

We conducted a multicenter, open-label, randomized, controlled trial with a two-group, parallel, group-sequential design. During a 6-month run-in phase, supportive care (in particular, blockade of the renin-angiotensin system) was adjusted on the basis of proteinuria. Patients who had persistent proteinuria with urinary protein excretion of at least 0.75 g per day were randomly assigned to receive supportive care alone (supportive-care group) or supportive care plus immunosuppressive therapy (immunosuppression group) for 3 years. The primary end points in hierarchical order were full clinical remission at the end of the trial (protein-to-creatinine ratio <0.2 [with both protein and creatinine measured in grams] and a decrease in the estimated glomerular filtration rate [eGFR] of <5 ml per minute per 1.73 m(2) of body-surface area from baseline) and a decrease in the eGFR of at least 15 ml per minute per 1.73 m(2) at the end of the trial. The primary end points were analyzed with the use of logistic-regression models.

RESULTS

The run-in phase was completed by 309 of 337 patients. The proteinuria level decreased to less than 0.75 g of urinary protein excretion per day in 94 patients. Of the remaining 162 patients who consented to undergo randomization, 80 were assigned to the supportive-care group, and 82 to the immunosuppression group. After 3 years, 4 patients (5%) in the supportive-care group, as compared with 14 (17%) in the immunosuppression group, had a full clinical remission (P=0.01). A total of 22 patients (28%) in the supportive-care group and 21 (26%) in the immunosuppression group had a decrease in the eGFR of at least 15 ml per minute per 1.73 m(2) (P=0.75). There was no significant difference in the annual decline in eGFR between the two groups. More patients in the immunosuppression group than in the supportive-care group had severe infections, impaired glucose tolerance, and weight gain of more than 5 kg in the first year of treatment. One patient in the immunosuppression group died of sepsis.

CONCLUSIONS

The addition of immunosuppressive therapy to intensive supportive care in patients with high-risk IgA nephropathy did not significantly improve the outcome, and during the 3-year study phase, more adverse effects were observed among the patients who received immunosuppressive therapy, with no change in the rate of decrease in the eGFR. (Funded by the German Federal Ministry of Education and Research; STOP-IgAN ClinicalTrials.gov number, NCT00554502.).

Immunoglobulin A nephropathy in horseshoe kidney: case reports and literature review

Horseshoe kidney is the most common congenital renal fusion anomaly. Immunoglobulin A nephropathy is a common glomerulonephritis worldwide. However, the co-occurrence of these diseases had not been reported in the literature. We report the first two cases with the occurrence of immunoglobulin A nephropathy in horseshoe kidney. The first case was a 26-year-old male with hypertension and proteinuria (1.4 g/24 h), his pathological finding was primary immunoglobulin A nephropathy. The second case was a 15-year-old female who presented with recurrent peliosis on bilateral lower extremities, haematuria and proteinuria (1.7 g/24 h). Her renal biopsy finding was Henoch-Schonlein purpura nephritis (secondary immunoglobulin A nephropathy). In both cases, renal biopsy was performed by experienced doctors under ultrasonic guidance at the renal upper pole and no postoperative complications were observed. After they were treated based on the renal pathological findings for 6 months, urine protein excretion decreased significantly and blood pressure and serum creatinine stabilized. It is possible that immunoglobulin A nephropathy occurs in a horseshoe kidney patient. Renal biopsy may be valuable and viable for horseshoe kidney patients with heavy proteinuria to identify pathologic type of glomerulopathy and to guide treatment, if renal biopsy is performed by experienced doctors at the renal upper pole under renal ultrasonic guidance.

Pulmonary hemorrhage with hematuria: do not forget IgA nephropathy

IgA nephropathy is the commonest cause of glomerulonephritis worldwide, and is usually a renal-limited disease. In rare cases, IgA nephropathy may also present with a pulmonary–renal syndrome in which pulmonary hemorrhage is a critical feature. Patients presenting with IgA nephropathy and pulmonary hemorrhage have high morbidity and are at high risk for mortality unless rapid immunosuppressive therapy is instituted. We present a case of IgA nephropathy complicated by pulmonary hemorrhage in which immunosuppressive therapy led to a good outcome, and review the literature on similar cases and the outcome of therapy.

Diagnosis and monitoring of IgA nephropathy: the role of biomarkers as an alternative to renal biopsy

IgA nephropathy (IgAN) is the most prevalent form of chronic glomerulonephritis in the world. The underlying pathogenesis of this autoimmune disease comprises the formation of immune complexes, including glycan-specific IgA1 or IgG antibodies and an aberrant glycosylation of IgA1. Until now, anatomopathological analysis of renal biopsies is essential for the diagnosis of IgAN and different histological classification systems have been proposed, e.g. the Oxford classification. However, a percutaneous renal biopsy is frequently not performed for several reasons and the Oxford classification system has some limitations. Since the poor prognosis of IgAN patients is partly the result of a delayed diagnosis, there is an urgent need for reliable noninvasive biomarkers that might be applicable in routine clinical practice. This article reviews the advances on the understanding of the underlying pathophysiological mechanisms of IgAN and discusses in depth the recent development of new biomarkers, including the use of proteomics and microRNAs.

The long-term efficacy and safety of immunosuppressive therapy on the progression of IgA nephropathy: a meta-analysis of controlled clinical trials with more than 5-year follow-up

OBJECTIVE

To evaluate the long-term efficacy of immunosuppressive therapy on Immunoglobulin A nephropathy (IgAN).

METHODS

Trials with at least 5-year follow-up investigating immunosuppressive therapy were selected.

MAIN OUTCOME MEASURES

Primary outcome was end-stage renal disease (ESRD). Secondary outcome was deterioration in renal function defined as doubled serum creatinine or 50% reduction of eGFR.

RESULTS

Seven studies were enrolled. Immunosuppression lowered the risk for ESRD risk ratio (RR = 0.30, 95% CI 0.19 - 0.48, p < 0.00001) and deterioration in renal function (RR = 0.19, 95% CI 0.07 - 0.54, p = 0.002). As for pooled RRs of ESRD, there were four studies with < 7-year follow-up, three followed for > 7 years, four adopted corticosteroids, two used corticosteroids plus other immunosuppressive agents, four were from Asia, and three from Europe. Pooled RRs were 0.32 (95% CI, 0.18 - 0.58, p = 0.0001), 0.28 (95% CI, 0.13 - 0.59, p = 0.0009), 0.34 (95% CI, 0.17 - 0.67, p = 0.002), 0.29 (95% CI, 0.15 - 0.58, p = 0.0005), 0.37 (95% CI, 0.20 - 0.68, p = 0.001) and 0.23 (95% CI, 0.11 - 0.47, p < 0.0001), respectively. Immunosuppression was associated with an increased risk for adverse events (RR = 2.13, 95% CI 1.17 - 3.86, p = 0.01).

CONCLUSIONS

Immunosuppressive therapy for IgAN might reduce long-term risk of ESRD and deterioration in renal function but increase risk of adverse events, and the efficacy on patients from Europe and Asia might be similar. Addition of other immunosuppressive agents did not provide additional benefit.

Tonsillectomy for IgA nephropathy: a meta-analysis

BACKGROUND

The efficacy of tonsillectomy in immunoglobulin A nephropathy (IgAN) remains controversial. Our meta-analysis was intended to investigate its efficacy as an adjunct or independent treatment.

STUDY DESIGN

Meta-analysis of prospective and retrospective studies using PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials.

SETTING & POPULATION

Patients with IgAN treated with or without tonsillectomy.

SELECTION CRITERIA FOR STUDIES

Studies that compared clinical remission or end-stage renal disease (ESRD) in patients with IgAN with or without tonsillectomy.

INTERVENTION

Tonsillectomy.

OUTCOMES

Clinical remission and ESRD.

RESULTS

14 studies (1,794 patients) were included and a random-effects model was applied. There were significantly greater odds of clinical remission with tonsillectomy (10 studies, 1,431 patients; pooled OR, 3.40; 95% CI, 2.58-4.48; P<0.001). Sensitivity analysis to exclude the effects of renin-angiotensin system inhibitors yielded consistent results (6 studies, 671 patients; pooled OR for remission, 2.80; 95% CI, 1.91-4.09; P<0.001). In subgroup analysis of the remission outcome, tonsillectomy plus steroid pulse therapy was superior to steroid pulse therapy alone (7 studies, 783 patients; pooled OR, 3.15; 95% CI, 1.99-5.01; P<0.001), and tonsillectomy plus conventional steroid therapy was superior to conventional steroid therapy alone (2 studies, 159 patients; pooled OR, 4.13; 95% CI, 1.23-13.94; P=0.02). Tonsillectomy was superior to general treatment (3 studies, 187 patients; pooled OR for remission, 2.21; 95% CI, 1.20-4.05; P=0.01). In addition, tonsillectomy was associated with decreased odds of ESRD (9 studies, 873 patients; pooled OR, 0.25; 95% CI, 0.12-0.52; P<0.001). 2 sensitivity analyses, one excluding studies with less than 5 years' follow-up and another excluding the confounding effect of renin-angiotensin system inhibitors, yielded nearly the same reduction in ESRD risk (6 studies, 691 patients; pooled OR, 0.20; 95% CI, 0.11-0.36; P<0.001; and 6 studies, 547 patients; pooled OR, 0.24; 95% CI, 0.14-0.44; P<0.001).

LIMITATIONS

Most included studies were retrospective cohort studies; we were unable to adjust uniformly for potential confounding variables.

CONCLUSIONS

As adjunct or independent therapy, tonsillectomy may induce clinical remission and reduce the rates of ESRD in patients with IgAN.

Effect of tonsillectomy and its timing on renal outcomes in Caucasian IgA nephropathy patients

PURPOSE

The role of tonsillectomy in the treatment of IgA nephropathy in Caucasian patients is controversial.

METHODS

A retrospective cohort study was conducted in 264 patients with biopsy-proven primary IgA nephropathy to examine the association between tonsillectomy and long-term renal survival, defined as the incidence of estimated glomerular filtration rates (eGFRs) of ≤30 ml/min/1.73 m(2) or end-stage renal disease (the composite of initiation of dialysis treatment or renal transplantation). The association of tonsillectomy with renal end-points was examined using the Kaplan-Meier method and Cox models.

RESULTS

One-hundred and sixty-six patients did not undergo tonsillectomy (Group I, follow-up 130 ± 101 months) and 98 patients underwent tonsillectomy (Group II, follow-up 170 ± 124 months). The mean renal survival time was significantly longer for both end-points between those patients who underwent tonsillectomy (Group II) versus patients without tonsillectomy (Group I) (p < 0.001 and p = 0.005). The mean renal survival time was significantly longer for both end-points between those patients who had macrohaematuric episodes versus patients who had no macrohaematuric episodes (p = 0.035 and p = 0.019). Tonsillectomy, baseline eGFR and 24-h proteinuria were independent risk factors for both renal end-points.

CONCLUSION

Tonsillectomy may delay the progression of IgA nephropathy mainly in IgA nephropathy patients with macrohaematuria. Prospective investigation of the protective role of tonsillectomy in Caucasian patients is needed.