IgA nephropathy and Henoch-Schönlein purpura nephritis

The efficacy of rituximab in the treatment of IgA vasculitis nephritis

The utility of Rituximab (RTX) for IgA vasculitis nephritis (IgAVN) is not well established. Up to now, we analysed the largest samples of IgAVN patients treated by RTX with a total of 41 retrieved subjects up to December 29, 2023 in the present systematic review. We assessed the clinical profiles, efficacy, and safety of RTX treatments. The present review showed that the renal function tended to be stabilized (P = 1.000) and urinalysis tended to normalize after RTX treatment with no serious adverse events reported. Moreover, 40% (16/40) of patients was freed use of glucocorticoid after RTX administration (P < 0.001). The remission rate was 92.7% (38/41) and complete remission rate was 46.3% (19/41) in IgAVN patients. Interestingly, 76.9% (10/13) of IgAVN child patients achieved complete remission when compared with 32.1% (9/28) of adult patients (P = 0.017). In summary, our results support the benefit of RTX therapy in IgAVN patients, especially children subjects.

A narrative review of potential drug treatments for nephritis in children with IgA vasculitis (HSP)

Immunoglobulin A (IgA) vasculitis (IgAV, also known as Henoch-Schoenlein purpura, HSP) is the most common vasculitis of childhood. It usually presents with a simple, self-limiting disease course; however, a small subset of patients may develop kidney involvement (IgAV-N) which occurs 4-12 weeks after disease onset and is the biggest contributor to long-term morbidity. Treatment currently targets patients with established kidney involvement; however; there is a desire to work towards early prevention of inflammation during the window of opportunity between disease presentation and onset of significant nephritis. There are no clinical trials evaluating drugs which may prevent or halt the progression of nephritis in children with IgAV apart from the early use of corticosteroids which have no benefit. This article summarises the latest scientific evidence and clinical trials that support potential therapeutic targets for IgAV-N that are currently being developed based on the evolving understanding of the pathophysiology of IgAV-N. These span the mucosal immunity, B-cell and T-cell modulation, RAAS inhibition, and regulation of complement pathways, amongst others. Novel drugs that may be considered for use in early nephritis include TRF-budesonide; B-cell inhibiting agents including belimumab, telitacicept, blisibimod, VIS649, and BION-1301; B-cell depleting agents such as rituximab, ofatumumab, and bortezomib; sparsentan; angiotensin converting enzyme inhibitors (ACE-Is); and complement pathway inhibitors including avacopan, iptacopan, and narsoplimab. Further clinical trials, as well as pre-clinical scientific studies, are needed to identify mechanistic pathways as there may be an opportunity to prevent nephritis in this condition. Key Points • Kidney involvement is the main cause of long-term morbidity and mortality in IgA vasculitis despite the current treatment recommendations. • The evolving understanding of the pathophysiology of IgA vasculitis is allowing exploration of novel treatment options which target underlying immune pathways. • Novel treatments currently being trialled in IgA nephropathy may have benefit in IgA vasculitis due to the similarities in the underlying pathophysiology, such as TRF-budesonide, B-cell modulators, and complement inhibitors. • Further studies, including clinical trials of novel drugs, are urgently needed to improve the long-term outcomes for children with IgA vasculitis nephritis.

IgA Vasculitis Followed by IgA Nephropathy Without an Identifiable Trigger: The Same Disease or a Spectrum of Related Conditions?

IgA vasculitis and IgA nephropathy are characterized by IgA deposition in blood vessels and glomerular mesangium, respectively. The former is far more common in the pediatric population, while the latter presents more often in adulthood. A consensus regarding whether these two conditions are manifestations of the same disease that occurs on a spectrum has not yet been reached, and, to our knowledge, no clinical trials to address this question have been conducted. Here, we describe a 27-year-old patient who presented to the emergency department multiple times before being diagnosed with IgA vasculitis with no identifiable trigger and soon after developed IgA nephropathy. This case highlights the importance of ruling out these conditions, especially IgA vasculitis, in adults presenting with a petechial rash, but also the need for studies that investigate whether and how these conditions are related so that patients can be appropriately diagnosed and treated as efficiently as possible.

Mucosal Immune Defence Gene Polymorphisms as Relevant Players in the Pathogenesis of IgA Vasculitis?

ITGAM-ITGAX (rs11150612, rs11574637), VAV3 rs17019602, CARD9 rs4077515, DEFA (rs2738048, rs10086568), and HORMAD2 rs2412971 are mucosal immune defence polymorphisms, that have an impact on IgA production, described as risk loci for IgA nephropathy (IgAN). Since IgAN and Immunoglobulin-A vasculitis (IgAV) share molecular mechanisms, with the aberrant deposit of IgA1 being the main pathophysiologic feature of both entities, we assessed the potential influence of the seven abovementioned polymorphisms on IgAV pathogenesis. These seven variants were genotyped in 381 Caucasian IgAV patients and 997 matched healthy controls. No statistically significant differences were observed in the genotype and allele frequencies of these seven polymorphisms when the whole cohort of IgAV patients and those with nephritis were compared to controls. Similar genotype and allele frequencies of all polymorphisms were disclosed when IgAV patients were stratified according to the age at disease onset or the presence/absence of gastrointestinal or renal manifestations. Likewise, no ITGAM-ITGAX and DEFA haplotype differences were observed when the whole cohort of IgAV patients, along with those with nephritis and controls, as well as IgAV patients, stratified according to the abovementioned clinical characteristics, were compared. Our results suggest that mucosal immune defence polymorphisms do not represent novel genetic risk factors for IgAV pathogenesis.

IgA Nephropathy: Current Treatment and New Insights

IgA Nephropathy (IgAN) is the most common cause of primary glomerulonephritis worldwide. Despite the histopathologic hallmark of mesangial IgA deposition, IgAN is a heterogenous autoimmune disease not only in terms of clinical presentation but also in long-term disease progression. The pathogenesis of the disease is complex and includes the generation of circulating IgA immune complexes with chemical and biological characteristics that favor mesangial deposition and reaction to mesangial under-glycosylated IgA1 accumulation, which leads to tissue injury with glomerulosclerosis and interstitial fibrosis. Patients with proteinuria over 1 g, hypertension, and impaired renal function at diagnosis are considered to be at high risk for disease progression and end-stage kidney disease (ESKD). Glucocorticoids have been the mainstay of treatment for these patients for years, but without long-term benefit for renal function and accompanied by several adverse events. A better understanding of the pathophysiology of IgAN in recent years has led to the development of several new therapeutic agents. In this review, we summarize the current therapeutic approach for patients with IgAN as well as all novel investigational agents.

Bibliometric analysis of IgA vasculitis nephritis in children from 2000 to 2022

Background

IgA vasculitis Nephritis (IgAVN) is a kidney-damaging disease that occurs during the course of IgA vasculitis (IgAV) and is the most serious complication of IgAV. However, there is a lack of reports of bibliometric analysis of IgAVN in children. The purpose of this study is to conduct a bibliometric analysis of IgAVN in children from 2000 to 2022, to explore the current status and cutting-edge trends in the field of IgAVN in children, and to establish new directions for subsequent research.

Methods

Screening the literature in the field of IgAVN in children in the Web of Science Core Collection (WoSCC) from 2000 to 2022. Visual analysis of their annual publications, countries, institutions, authors, journals, keywords, and references were using CiteSpace5.8.R3 and VOSviewer1.6.18.

Results

A total of 623 publications were included in the study, since the beginning of 2014, there has been an overall increasing trend in the number of articles issued. The most prolific country and institution were China and Zhejiang University. The most frequently cited author was Coppo R, with 331 citations, who has made great contributions to IgAVN. Mao Jianhua, Lee JS and Wyatt Robert J were the most prolific authors, all with 9 articles. Pediatric Nephrology was the most published and cited journal. The highest burst strength keyword is IgA vasculitis, and the highest burst strength reference is Davin JC, 2014.

Conclusion

The research hotspots and trends predicted by the analysis of this study provide a reference for in-depth research in this field with a view to promoting the development of IgAVN research in children.

Comparison of clinical, pathological and long-term renal outcomes of children with Henoch-Schonlein purpura nephritis and IgA nephropathy

PURPOSE

To compare clinical, pathological, and long-term renal outcomes of children with Henoch-Schonlein purpura nephritis (HSPN) and IgA nephropathy (IgAN).

METHODS

The medical records of patients diagnosed as HSPN and IgAN during childhood were evaluated retrospectively. HSPN and IgAN groups were compared in terms of gender, age, upper respiratory infection history, blood pressure; presence of nephrotic and/or nephritic syndrome; hemoglobin level, leukocyte count, C-reactive protein (CRP), serum albumin (sAlb), creatinine, complement 3 (sC3), complement 4 (sC4) and immunoglobulin A (sIgA) levels; estimated glomerular filtration rate (eGFR) and proteinuria levels; and renal pathology findings at the onset of disease; total follow-up time; and blood pressure, eGFR and proteinuria levels at the last visit.

RESULTS

Fifty-four patients were enrolled in the study [38 (70%) HSPN and 16 (30%) IgAN]. The median follow-up time was 60.5 and 72.0 months in HSPN and IgAN groups, respectively (p > 0.05). The HSPN and IgAN groups were also not different in terms of gender, age at the onset; leukocyte count, eGFR, sC3-sC4-sIgA levels; and the presence of endocapillary, extracapillary and mesangial proliferation, tubular atrophy, interstitial fibrosis and IgA, IgM, C3 accumulation in renal tissue. Upper respiratory tract infection history was more common in children with IgAN (8/16 vs 8/38, p = 0.045). sAlb (3.96 ± 0.58 vs 4.40 ± 0.46 g/dL, p = 0.005), hemoglobin (12.1 ± 1.3 vs 13.3 ± 1.2 g/dL, p = 0.004,) and the incidence of mesangial IgG deposition (15/38 vs 11/16, p = 0.049) were lower, while CRP (16.3 ± 7.2 vs 7.8 ± 4.4 mg/L, p = 0.002) and proteinuria (72.1 ± 92.4 vs 34.2 ± 37.9 mg/m²/24 h, p = 0.041) was higher in HSPN group at the onset of disease. Proteinuria and eGFR were similar between the two groups at last visit.

CONCLUSION

Children with HSPN and IgAN have little clinical and histological differences in our population. The most prominent difference at presentation with nephritis was higher proteinuria in HSPN probably associated with inflammation due to systemic vasculitis. Long-term renal outcome was good in both HSPN and IgAN.

IgA Vasculitis and IgA Nephropathy: Same Disease?

Many authors suggested that IgA Vasculitis (IgAV) and IgA Nephropathy (IgAN) would be two clinical manifestations of the same disease; in particular, that IgAV would be the systemic form of the IgAN. A limited number of studies have included sufficient children or adults with IgAN or IgAV (with or without nephropathy) and followed long enough to conclude on differences or similarities in terms of clinical, biological or histological presentation, physiopathology, genetics or prognosis. All therapeutic trials available on IgAN excluded patients with vasculitis. IgAV and IgAN could represent different extremities of a continuous spectrum of the same disease. Due to skin rash, patients with IgAV are diagnosed precociously. Conversely, because of the absence of any clinical signs, a renal biopsy is practiced for patients with an IgAN to confirm nephropathy at any time of the evolution of the disease, which could explain the frequent chronic lesions at diagnosis. Nevertheless, the question that remains unsolved is why do patients with IgAN not have skin lesions and some patients with IgAV not have nephropathy? Larger clinical studies are needed, including both diseases, with a common histological classification, and stratified on age and genetic background to assess renal prognosis and therapeutic strategies.

IgA Nephropathy: An Interesting Autoimmune Kidney Disease

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is a leading cause of chronic kidney disease and progresses to end-stage kidney disease in up to 40% of patients about 20 years after diagnosis. Additionally, IgAN is associated with significant mortality. The diagnosis currently necessitates a kidney biopsy, as no biomarker sufficiently specific and sensitive is available to supplant the procedure. Patients display significant heterogeneity in the epidemiology, clinical manifestations, renal progression, and long-term outcomes across diverse racial and ethnic populations. Recent advances in understanding the underlying pathophysiology of the disease have led to the proposal of a four-hit hypothesis supporting an autoimmune process. To date, there is no disease-specific treatment but, with a better understanding of the disease pathogenesis, new therapeutic approaches are currently being tested in clinical trials. In this review, we examine the multiple facets and most recent advances of this interesting disease.

Henoch-Schönlein purpura in Saudi Arabia: characteristics and rare vital organ involvement

Henoch-Schönlein purpura (HSP) is the most common small vessel vasculitis in children with an annual incidence of between 10 and 30 per 100,000. It is an inflammation that affects many organs primarily in the skin, gastrointestinal (GI) tract, musculoskeletal, also vital organs like kidneys and lungs which may lead to chronic kidney disease and pulmonary hemorrhage. In this review, we are showing the characteristics of Saudi patients with HSP and the relation with preceding infections, gender, and seasonal variations in addition to the common and most severe systemic involvements. We found cases that were challenging to diagnose and others with unfortunate fetal complications.

Measuring Vasculitis with Numbers: Outcome Scores

Primary Systemic Vasculitides (PSV) are a heterogeneous group of diseases. Outcome scores are important to evaluate vasculitis patients in a more structured and standard way and these help physicians to predict patients with poor prognosis or high risk of relapse. Furthermore, we need reliable outcome measures for clinical trials. There are a number of vasculitis outcome scores available in the clinical practice with different strengths and limitations. These are mainly measures of disease activity, disease damage, response to treatment and quality of life. Birmingham Vasculitis Activity Score (BVAS) and its pediatric version aim to evaluate a wide scope of PSV. On the other hand, some outcome studies have focused on a single vasculitis type since the whole group includes different diseases with heterogeneous clinical features. The aim of this review is to provide an overview on outcome measures currently being used in the evaluation of patients with PSV. We mainly focus on immunoglobulin A vasculitis/Henochschönlein purpura, Kawasaki disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, polyarteritis nodosa, Takayasu arteritis and Behçet's disease.

Autoantibodies Specific for Galactose-Deficient IgA1 in IgA Vasculitis With Nephritis

Introduction

Patients with IgA nephropathy (IgAN) have elevated serum levels of galactose-deficient IgA1 (Gd-IgA1) that are bound by Gd-IgA1–specific autoantibodies in pathogenic immune complexes. Renal biopsy histopathologic features of IgA vasculitis (IgAV) with nephritis (IgAV-N) are similar to those of IgAN. Mucosal infections often are associated with clinical onset and exacerbation in both diseases. We investigated whether patients with IgAV-N share pathogenic characteristics of IgAN.

Methods

We generated IgA1- and IgG-secreting cell lines from Epstein-Barr virus (EBV)–immortalized cells of patients with IgAV without nephritis (IgAV-woN), IgAV-N, and IgAN and from healthy individuals. Sera and cell-culture supernatants were used for analysis of Gd-IgA1 and Gd-IgA1–specific IgG autoantibodies.

Results

IgA1-producing cells from patients with IgAV-N, like cells from patients with IgAN, secreted more Gd-IgA1 than did cells from patients with IgAV-woN or healthy control subjects, in agreement with elevated serum Gd-IgA1 levels in patients with IgAV-N and IgAN. IgA1-producing cells from patients with IgAV-N had altered expression of genes involved in O-glycan biosynthesis: decreased for core 1 synthase (glycoprotein-N-acetylgalactosamine 3-β-galactosyltransferase 1; C1GALT1) and C1GALT1 Specific Chaperone 1 (C1GALTC1; COSMC) and elevated for N-acetylgalactosaminide α-2,6-sialyltransferase 2 (ST6GALNAC2). Levels of Gd-IgA1–specific IgG in sera and supernatants of IgG-producing cells were similar for patients with IgAV-N and IgAN and higher than those for IgAV-woN patients or healthy control subjects. Moreover, patients with IgAV-N who had active disease, manifested by hematuria and substantial proteinuria, had higher serum levels of Gd-IgA1–specific IgG autoantibodies than did patients with IgAV-N who had inactive disease.

Conclusion

Serum levels and cellular production of Gd-IgA1 and Gd-IgA1–specific IgG autoantibodies were elevated in patients with IgAV-N, supporting the hypothesis that IgAV-N and IgAN share pathogenic features.

Variation in complement factor H affects complement activation in immunoglobulin A vasculitis with nephritis

BACKGROUND

Immunoglobulin A (IgA) vasculitis with nephritis (IgAVN) and IgA nephropathy (IgAN) are widely considered as related diseases. Considerable evidences support the notion of involvement of complement activation in both IgAVN and IgAN. Our previous studies identified a genetic variant in complement factor H (CFH), rs6677604, as an IgAN-susceptible variant by genome-wide association study, and further confirmed its linkage to CFHR3-1Δ and proved its influence on complement activation and thereby on IgAN susceptibility.

AIM

To explore the role of rs6677604 in complement activation of IgAVN.

METHODS

In this study, we enrolled 632 patients with IgAVN, 1178 patients with IgAN and 902 healthy controls. The genotype of rs6677604 was measured by TaqMan allele discrimination assays or was extracted from genome-wide association study data.

RESULTS

The frequency of the rs6677604-A allele was significantly higher in IgAVN than in IgAN. However, no significant differences were observed between IgAVN and the controls. Higher complement factor H (FH) levels were observed in IgAVN than IgAN, and positive correlation between circulating FH and C3 levels was present in IgAVN. In both IgAVN and IgAN, rs6677604-A was associated with less intensity of glomerular C3 deposits. In agreement with the higher frequency of rs6677604-A in IgAVN, the glomerular C3 deposits of patients with IgAVN were less intense than those in IgAN.

CONCLUSION

Our findings suggest that genetic variation in CFH (rs6677604) is involved in the phenotype of complement activation in both IgAVN and IgAN. Moreover, rs6677604 might contribute to the difference of complement activation intensity between IgAVN and IgAN.

Value of the Oxford classification of IgA nephropathy in children with Henoch-Schönlein purpura nephritis

BACKGROUND

The widely used International Study of Kidney Disease in Children (ISKDC) classification for Henoch-Schönlein purpura nephritis (HSPN) does not completely correlate with the clinical presentation and long-term prognosis of this disease. Primary IgA nephropathy (IgAN) and HSPN share common features; thus, the Oxford classification of IgAN might be useful in predicting the long-term outcomes of HSPN. However, its value has not been confirmed in children with HSPN.

METHODS

We selected children with HSPN diagnosed between 2003 and 2015, and reclassified their renal biopsies according to the Oxford classification scoring system. The primary outcome was impaired renal function, and remission of proteinuria and clinical remission were secondary outcomes.

RESULTS

We included 104 patients (58 males, 46 females) with a median age of 10 (4-17) years. Mesangial hypercellularity (M1) was strongly associated with proteinuria, and tubular atrophy/interstitial fibrosis (T1&2) and C2 (with crescents in > 25% of glomeruli) were associated with reduced estimated glomerular filtration rate (eGFR) at the time of biopsy. Patients with M1, endocapillary proliferation (E1), segmental glomerulosclerosis (S1), and crescents (C1&2) were more likely to have been treated with high-dose methylprednisolone. At univariate time-dependent analyses, S1 was strongly associated with the primary outcome (p = 0.025), whereas T1&2 was significantly negatively associated with proteinuria remission (p = 0.035) and clinical remission (p = 0.038).

CONCLUSIONS

Our findings suggest that the Oxford classification is valid for children with HSPN. S and T lesions, which are ignored in the ISKDC classification, can be used to assess renal outcomes of HSPN, and such assessments are not affected by currently available treatments. The value of M, E and C lesions in predicting response to therapy and renal outcome warrants further study.

IgA nephropathy during treatment with TNF-alpha blockers: Could it be predicted?

Immunoglobulin A (IgA) nephropathy (IgAN) may sometimes be related to exposure to pharmacological agents, among which anti-Tumor Necrosis Factor (TNF)-alpha agents. The characteristic pathological feature is a deposition of IgA-containing immune complexes in vessel walls in the kidney mesangium. The link between TNF-alpha blockers and IgAN may be hypothesized examining diseases which share pathologic features. In this respect, idiopathic IgAN and Henoch Schonlein Purpura have been the object of studies revealing a pathogenetic role of aberrant glycosylation of IgA1 molecules. The Authors suggest that anti-drug antibodies against glycan structures of TNF-alpha inhibitors may cross react against serum aberrant IgA1 leading to large antigen-antibody complexes. These large polymeric IgA complexes are then able to deposit in the mesangium and activate the complement cascade. Such hypothesis may be tested by measuring serum levels of galactose-deficient IgA1 of patients developing IgAN following introduction of TNF-alpha blockers. Such a test would be useful also before administration of anti-TNF alpha agents. The presence of aberrant IgA1 may represent a contraindication for treatment with TNF blockers.

A case of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome complicated by IgA nephropathy with nephrotic syndrome

A 62-year-old man visited our hospital with a mild sore throat, high-grade fever, and clavicular pain. Seven years earlier, he had been diagnosed with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. His clavicles were tender and remarkably swollen. Also noted was marked pitting edema in the lower extremities and pustulosis on the palms and soles of the feet. Laboratory studies on admission showed an elevated white cell count (23,400/μl) and serum C-reactive protein level (24.4 mg/dl). Urinalysis revealed proteinuria (2+) and occult blood (3+) with numerous dysmorphic red blood cells and hyalin casts. The patient was diagnosed with recurrence of his SAPHO syndrome and started on oral glucocorticoid therapy. By day 9 after admission, he had gained 16 kg in body weight, and his proteinuria (6.4 g/day) and serum creatinine level (2.3 mg/dl) were elevated. Renal biopsy revealed mesangial proliferative glomerulonephritis with deposition of IgA and C3 in the mesangial area and along the capillary walls. The patient was diagnosed with IgA nephropathy accompanied by nephrotic syndrome. With oral prednisolone therapy, his fever, clavicular pain, and proteinuria were gradually relieved. The clinical course in this case suggests the onset of nephrotic syndrome with IgA nephropathy was associated with the recurrence of the patient's SAPHO. To our knowledge, this is the first reported case of SAPHO-associated IgA nephropathy.

Familial Henoch-Schönlein Syndrome

Little attention has been so far paid to familial cases of Henoch-Schönlein syndrome. We performed a search of the Medical Subject Headings terms (Henoch or Schönlein OR anaphylactoid purpura OR IgA nephropathy OR Berger nephropathy) AND (family OR familial). We identified no more than 19 reports including 47 families with a total of 100 affected cases: their ages ranged from 1.3 to 51 years (median, 11 years), with a male-to-female ratio of 1.4. Familial cases developed simultaneously in 45% and nonsimultaneously in 55% of the families. Age, male-to-female ratio, and clinical findings were not statistically different in cases with simultaneous and nonsimultaneous familial occurrence of Henoch-Schönlein syndrome. Henoch-Schönlein syndrome occurs almost always sporadically. Age at presentation, male-to-female ratio, and findings are similar in familial (both simultaneously and nonsimultaneously occurring) and sporadic Henoch-Schönlein cases.

Risk Factors Associated with Renal Involvement in Childhood Henoch-Schönlein Purpura: A Meta-Analysis

BACKGROUND AND OBJECTIVE

Henoch-Schönlein purpura (HSP) is an important cause of chronic kidney disease in children. This meta-analysis identified risk factors associated with renal involvement in childhood HSP.

METHODS

PubMed, Embase, and Web of Science were searched. The quality of all eligible studies was assessed using the Newcastle-Ottawa scale criteria. An analysis of possible risk factors was conducted to report the odds ratio (OR) and weighted mean difference (WMD).

RESULTS

Thirteen studies (2398 children) revealed 20 possible and 13 significant risk factors associated with renal involvement in HSP, with the following meta-analysis estimates of OR and WMD, with 95% confidence intervals: older age (0.90, 0.61-1.19); age > 10 y (3.13, 1.39-7.07); male gender (1.36, 1.07-1.74); abdominal pain (1.94,1.24-3.04); gastrointestinal bleeding (1.86, 1.30-2.65); severe bowel angina (3.38, 1.17-9.80); persistent purpura (4.02, 1.22-13.25); relapse (4.70, 2.42-9.14); WBC > 15 × 109/L (2.42, 1.39-4.22); platelets > 500 × 109/L (2.98, 1.22-7.25); elevated antistreptolysin O (ASO) (2.17, 1.29-3.64); and decreased complement component 3 (C3) (3.13, 1.62-6.05). Factors not significantly associated with renal involvement were: blood pressure; orchitis; elevated C-reactive protein; elevated erythrocyte sedimentation rate (ESR); and elevated serum IgA/IgE or IgG. Arthritis/arthralgia may be a risk factor according to the criteria of the American College of Rheumatology (1.41, 1.01-1.96).

CONCLUSION

The following are associated with renal involvement in pediatric HSP: male gender; > 10 y old; severe gastrointestinal symptoms (abdominal pain, gastrointestinal bleeding, and severe bowel angina); arthritis/arthralgia; persistent purpura or relapse; WBC > 15 × 109/L; platelets > 500 × 109/L; elevated ASO; and low C3. Relevant clinical interventions for these risk factors may exert positive effects on the prevention of kidney disease during the early stages of HSP. However, the results should be interpreted cautiously due to the limitations of the studies.

Circulating midkine in children with Henoch-Schönlein purpura: Clinical implications

BACKGROUND

Midkine (MK) is a heparin-binding growth factor, which behaves like a cytokine, involved in various cellular processes such as cellular proliferation, differentiation, survival, adhesion, and migration. Studies provided evidence for a role of MK in acute and chronic inflammatory processes. The association between midkine and Henoch-Schönlein purpura (HSP) has not yet been explored. The aim of our study was to investigate the potential role of midkine in children with HSP.

METHODS

A total of 152 cases consisting of 92 children with HSP and 60 age- and sex-matched healthy control children were enrolled in this prospective study. Circulating midkine, IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17A was measured in all of the 92 patients and 60 healthy controls. Midkine diagnostic value was evaluated by receiver operating characteristic (ROC) analysis.

RESULTS

Renal involvement occurred in 36 of the 92 patients. Circulating midkine level was elevated in children with HSPN than those of patients without renal involvement and of the controls (326.58 (266.58-459.25) pg/ml versus 280.72 (233.67-384.36) pg/ml and 217.3 (198.98-243.65) pg/ml, respectively; P<0.05). Midkine positively correlated with IL-4, IL-6, IL17A, IgA and IgE. The threshold MK concentration of HSPN was 295.58pg/ml, with the sensitivity and specificity of 80.6% and 88.3%, respectively. The area under the receiver operating characteristic (ROC) curve (AUCROC) of MK was 0.902.

CONCLUSIONS

MK seems to be involved in the development of HSP. Measurement of serum levels of MK is helpful in confirming the diagnosis of HSP and predicting HSPN.

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.

Assessment of the effect of mesangial hypercellularity in childhood nephropathies to the clinical and laboratory findings

AIM

To assess the relationship between mesangial hypercellularity in various childhood nephropathies and clinical and laboratory parameters.

METHODS AND PATIENTS

The reports of the renal biopsies were evaluated retrospectively. The patients with diagnosis of IgA nephropathy (isolated and Henoch-Schönlein nephritis), IgM nephropathy, or isolated mesangial proliferative glomerulonephritis were included. Each nephropathy group was divided into two subgroups according to the severity of mesangial hypercellularity as mild and severe. The biochemical data and histopathological findings of the patients were recorded.

RESULTS

When the groups were compared, it was found that the patients with IgA nephropathy had hematuria (p = 0.043) and the patients with IgM nephropathy had nephrotic syndrome more frequently than the other patients (p = 0.01). No difference was detected between the groups regarding the severity of mesangial hypercellularity. On the other hand, when the groups were evaluated within themselves, no significant association was detected between the severity of mesangial hypercellularity and clinical and laboratory parameters. It was determined that the renal biopsy was performed earlier in patients with Henoch-Schönlein nephritis compared to the other cases (p = 0.004). Compared to the isolated IgA nephropathy group, it was found that the number of cases with severe mesangial hypercellularity was higher and the level of proteinuria was more prominent in patients with Henoch-Schönlein nephritis. Additionally, when the patients with Henoch-Schönlein nephritis were evaluated, the degree of proteinuria was found to be higher in patients with severe mesangial hypercellularity compared to those of showing mild mesangial hypercellularity (p = 0.002).

CONCLUSION

It was observed that there is no direct relation between the severity of mesangial hypercellularity and clinical and laboratory findings in various childhood nephropathies. However, when Henoch-Schönlein nephritis is compared with IgA nephropathy, it was found that the severity of mesangial hypercellularity was higher in cases with Henoch-Schönlein nephritis and the level of proteinuria was more prominent in those cases. However, no difference was detected in glomerular filtration rates and biochemical data with regard to the level of mesangial hypercellularity.

Henoch-Schönlein purpura in children

Henoch-Schönlein purpura is the most common systemic vasculitis of childhood. In the majority of children, the outcome of Henoch-Schönlein purpura is excellent with spontaneous resolution of symptoms and signs. However, a small subset of patients will develop long-term sequelae in the form of chronic kidney disease. While the clinical presentation and diagnosis of Henoch-Schönlein purpura is straightforward, treatment of Henoch-Schönlein purpura nephritis and long-term renal outcomes of more severely affected children are less certain. This review article gives a general overview of Henoch-Schönlein purpura with emphasis on recently published information, including the new classification of childhood vasculitis, insights into pathogenesis of Henoch-Schönlein purpura and a summary of various treatments of established Henoch-Schönlein purpura nephritis.

Increased number of Th22 cells and correlation with Th17 cells in peripheral blood of patients with IgA nephropathy

T-helper (Th) 22 and Th17 cells are involved in the pathogenesis of autoimmune diseases. However, the role of Th22 and correlation with Th17 cells in the pathophysiology of IgA nephropathy (IgAN) remain unknown. In our study, Th22 and Th17 cells in peripheral blood of IgAN patients, non-IgA mesangial proliferative glomerulonephritis (non-IgA MsPGN) patients, and healthy controls were measured by flow cytometry. The concentration of plasma interleukin-22 (IL-22) was examined by enzyme linked immunosorbent assay (ELISA). The results showed that Th22 cells, Th17 cells, and plasma IL-22 were significantly elevated in IgAN patients compared with non-IgA MsPGN patients and healthy controls. Th22 cells showed a positive correlation with the levels of plasma IL-22 in IgAN patients. Moreover, a significantly positive correlation between Th22 cells and Th17 in IgAN patients was observed. Furthermore, IgAN patients with proteinuria showed a higher percentage of Th22 cells than IgAN patients without proteinuria. Our data demonstrated that IgAN had increased frequencies of peripheral Th22, Th17 cells and plasma IL-22, indicating that Th22 along with Th17 cells are involved in the immune responses of IgAN.

Soluble transferrin receptor in urine, a new biomarker for IgA nephropathy and Henoch-Schönlein purpura nephritis

OBJECTIVES

IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephritis (HSPN) might represent different ends of a continuous spectrum of glomerular disease. In both conditions, upregulated soluble transferrin receptor (sTfR) might be excreted in urine, which could be a potential biomarker to monitor disease activity and therapeutic response.

METHODS

In this pilot study, 132 Caucasian patients consulting the Nephrology Department at the Ghent University Hospital because of a glomerulopathy and 50 normal controls were included. Urinary sTfR concentrations were determined in concentrated urine using a newly developed latex-enhanced immunonephelometric assay.

RESULTS

Median urinary sTfR concentration was higher in patients with a primary glomerulopathy than in healthy subjects (p<0.0001). More importantly, absolute median levels of urinary sTfR were markedly higher in patients with active IgAN or HSPN [10μg/L, 95% confidence interval (CI): 6-18μg/L] in comparison with those with other morphological types of glomerulopathy (2μg/L, 95%CI: 1-4μg/L) (p<0.0001). A statistically significant difference in urinary sTfR concentration was observed between patients with active IgAN or HSPN and patients who had achieved partial or complete remission (p<0.0001). Multiple regression analysis with urinary sTfR as dependent variable revealed that proteinuria was the main predictor of urinary sTfR concentration (r(2)=0.52, p<0.001).

CONCLUSION

Determination of sTfR in urine is a new and sensitive method for a potential biomarker of IgAN and HSPN.

Pathogenesis of IgA nephropathy

Since its first description in 1968, IgA nephropathy has remained the most common form of idiopathic glomerulonephritis leading to chronic kidney disease in developed countries. The exact pathogenesis of IgA nephropathy is still not well defined. Current data implicate an important genetic factor, especially in promoting the overproduction of an aberrant form of IgA1. The immunochemical aberrancy of IgA nephropathy is characterized by the undergalactosylation of O-glycans in the hinge region of IgA1. However, such aberrant glycosylation alone does not cause renal injury. The next stage of disease development requires the formation of glycan-specific IgG and IgA antibodies that recognize the undergalactosylated IgA1 molecule. These antibodies often have reactivity against antigens from extrinsic microorganisms and might arise from recurrent mucosal infection. B cells that respond to mucosal infections, particularly tonsillitis, might produce the nephritogenic IgA1 molecule. With increased immune-complex formation and decreased clearance owing to reduced uptake by the liver, IgA1 binds to the glomerular mesangium via an as yet unidentified receptor. Glomerular IgA1 deposits trigger the local production of cytokines and growth factors, leading to the activation of mesangial cells and the complement system. Emerging data suggest that mesangial-derived mediators following glomerular deposition of IgA1 lead to podocyte and tubulointerstitial injury via mesangio-podocytic-tubular crosstalk. This Review summarizes the latest findings in the pathogenesis of IgA nephropathy.

Mice overexpressing BAFF develop a commensal flora-dependent, IgA-associated nephropathy

B cell activation factor of the TNF family (BAFF) is a potent B cell survival factor. BAFF overexpressing transgenic mice (BAFF-Tg mice) exhibit features of autoimmune disease, including B cell hyperplasia and hypergammaglobulinemia, and develop fatal nephritis with age. However, basal serum IgA levels are also elevated, suggesting that the pathology in these mice may be more complex than initially appreciated. Consistent with this, we demonstrate here that BAFF-Tg mice have mesangial deposits of IgA along with high circulating levels of polymeric IgA that is aberrantly glycosylated. Renal disease in BAFF-Tg mice was associated with IgA, because serum IgA was highly elevated in nephritic mice and BAFF-Tg mice with genetic deletion of IgA exhibited less renal pathology. The presence of commensal flora was essential for the elevated serum IgA phenotype, and, unexpectedly, commensal bacteria-reactive IgA antibodies were found in the blood. These data illustrate how excess B cell survival signaling perturbs the normal balance with the microbiota, leading to a breach in the normal mucosal-peripheral compartmentalization. Such breaches may predispose the nonmucosal system to certain immune diseases. Indeed, we found that a subset of patients with IgA nephropathy had elevated serum levels of a proliferation inducing ligand (APRIL), a cytokine related to BAFF. These parallels between BAFF-Tg mice and human IgA nephropathy may provide a new framework to explore connections between mucosal environments and renal pathology.

IgA1 immune complexes from pediatric patients with IgA nephropathy activate cultured human mesangial cells

BACKGROUND

Circulating immune complexes (CIC) containing galactose (Gal)-deficient IgA1 from adults with IgA nephropathy (IgAN) induce proliferation of cultured mesangial cells, but activities of CIC from pediatric patients with the disease have not been studied.

METHODS

CIC of different sizes were isolated from sera of pediatric and adult IgAN patients and their effects on cultured human mesangial cells (MC) were assessed by measuring cellular proliferation, expression of IL-6 and IL-8 and laminin and phosphotyrosine signaling.

RESULTS

Large CIC from pediatric IgAN patients (>800 kDa) containing Gal-deficient IgA1 stimulated cellular proliferation, whereas in some patients, smaller CIC were inhibitory. Addition of stimulatory and inhibitory CIC to MC differentially altered phosphorylation patterns of three major tyrosine-phosphorylated proteins of molecular mass 37, 60 and 115 kDa. The stimulatory CIC transiently increased tyrosine-phosphorylation of the 37-kDa protein and decreased phosphorylation of the other two proteins, whereas the inhibitory CIC increased phosphorylation of all three proteins. Furthermore, we investigated the influence of IgA1-containing CIC from sera of children with IgAN with clinically active disease (i.e., abnormal urinalysis and/or serum creatinine concentration) or inactive disease (i.e., normal urinalysis and serum creatinine concentration) on the expression of IL-6 and IL-8 genes by mesangial cells. Real-time reverse transcription-polymerase chain reaction results showed that the CIC from a patient with active disease stimulated MC to express the two cytokine genes at higher levels than did the CIC from a patient with inactive disease. Moreover, stimulatory CIC increased production of the extracellular matrix protein laminin.

CONCLUSION

These data indicate that sera of pediatric IgAN patients contain biologically active CIC with Gal-deficient IgA1.

Immune complexes in acute adult-onset Henoch-Schonlein nephritis

BACKGROUND

Adult-onset Henoch-Schönlein purpura nephritis (HSPN) and primary IgA (IgAN) nephropathy have been considered indistinguishable immunohistopathologically and are often considered as two extremes of one disease entity. We postulate that adult-onset Henoch-Schönlein can be distinguished histologically from primary IgAN and that both diseases differ in their immunopathological mechanisms.

METHODS

Twenty consecutive patients with adult-onset HSPN were studied. Serum was analysed for circulating IgA immune complexes; renal biopsies were analysed by light and electron microscopy (EM). As disease controls, 40 IgAN patients were studied.

RESULTS

Intracapillary leukocyte margination was seen in 15 of the 20 patients and cellular crescent formation in all renal biopsies of the HSPN patients. IgAN biopsies showed a few small crescents without intracapillary leukocytes. In 16 HSPN patients, EM was performed and in 10, no dense deposits were found. In all biopsies of IgAN patients, typical 'humps' were found. In 6 of 9 analysed HSPN patients, intermediate to large circulating immune complexes were found, whereas in 4 of 28 analysed patients with primary IgAN small circulating immune complexes were found.

CONCLUSIONS

We consider adult-onset HSPN distinguishable in histology and ultrastructure from primary IgAN. We believe adult-onset Henoch-Schönlein to be a circulating immune complex disease.

CD81 gene defect in humans disrupts CD19 complex formation and leads to antibody deficiency

Antibody deficiencies constitute the largest group of symptomatic primary immunodeficiency diseases. In several patients, mutations in CD19 have been found to underlie disease, demonstrating the critical role for the protein encoded by this gene in antibody responses; CD19 functions in a complex with CD21, CD81, and CD225 to signal with the B cell receptor upon antigen recognition. We report here a patient with severe nephropathy and profound hypogammaglobulinemia. The immunodeficiency was characterized by decreased memory B cell numbers, impaired specific antibody responses, and an absence of CD19 expression on B cells. The patient had normal CD19 alleles but carried a homozygous CD81 mutation resulting in a complete lack of CD81 expression on blood leukocytes. Retroviral transduction and glycosylation experiments on EBV-transformed B cells from the patient revealed that CD19 membrane expression critically depended on CD81. Similar to CD19-deficient patients, CD81-deficient patients had B cells that showed impaired activation upon stimulation via the B cell antigen receptor but no overt T cell subset or function defects. In this study, we present what we believe to be the first antibody deficiency syndrome caused by a mutation in the CD81 gene and consequent disruption of the CD19 complex on B cells. These findings may contribute to unraveling the genetic basis of antibody deficiency syndromes and the nonredundant functions of CD81 in humans.

Pathogenesis and management of bleeding and thrombosis in plasma cell dyscrasias

Unexpectedly high rates of venous thromboembolic events (VTE) concurrent with the introduction of highly effective immune modulating drugs thalidomide and lenolidomide for treatment of multiple myeloma have focused attention on the incidence and underlying pathophysiology of VTE in patients with plasma cell dyscrasias, and on thromboprophylaxis approaches. While bleeding complications are relatively uncommon in patients with lymphoproliferative disorders, acquired von Willebrand syndrome, typically occurring in patients with monoclonal gammopathy of unknown significance, and acquired coagulopathies associated with primary amyloidosis can present with haemorrhagic complications and both are challenging to manage. This review highlights these important haemostasis-related complications of plasma cell dyscrasias and provides an overview of other uncommon bleeding and thrombotic events that can affect diagnostic and therapeutic management of clonal plasma cell disorders. Due to the infrequency of most of these haemostasis complications, available information is typically based on retrospective cases or series.