The Spectrum of Children's Kidney Diseases—2403 Renal Biopsy-Proven Cases from a Single Centre in China Between 1999 and 2019

Background: This study aimed to investigate the clinical and pathological characteristics and the changes in glomerular diseases in 2403 pediatric renal biopsies from 1999 to 2019.Methods: Renal biopsies performed on children aged ≤18 years between 1999 and 2019 were analysed at our center. We analysed the clinical and histological characteristics, distribution of pediatric glomerular diseases with various clinical presentations, and changes in the glomerular disease patterns during the study period.Results: The most common primary glomerular disease was IgA nephropathy (IgAN) (24.3%), followed by minimal change disease (MCD) (15.3%) and membranous glomerulonephritis (MN) (13.1%). Henoch-Schonlein purpura nephritis (HSPN) (18.1%) and lupus nephritis (LN) (7.2%) were the most frequently recorded secondary glomerular diseases. Alport syndrome and thin basement membrane nephropathy (TBMN) were the most common inherited glomerular diseases, accounting for 1.2% and 0.6% of the total glomerular diseases in children, respectively. The number of boys with IgAN, MCD and IgM nephropathy (IgMN) was higher than that of girls, while the number of girls with MN and LN was higher than that of boys. The frequencies of MCD, MN, IgMN and endocapillary proliferative glomerulonephritis (EnPGN) in the 13-18-year-old group were higher than those in the 0-12-year-old group, while the frequencies of IgAN, mesangial proliferative glomerulonephritis (MsPGN) and focal proliferative glomerulonephritis (FPGN) were lower than those in the 0-12-year-old group. The ratio of Alport syndrome and TBMN in the 0-12-year-old group was higher than that in the 13-18-year-old group. The proportion of patients with MCD and MN in 2010-2019 was higher than that in 1999-2009, while the ratio of IgAN, MsPGN, IgMN, EnPGN, membranoproliferative glomerulonephritis (MPGN), HSPN and HBV-associated glomerulonephritis (HBV-GN) decreased. MCD (28.5%) was the most common cause of nephrotic syndrome (NS). In children with haematuria and proteinuria, HSPN (38.8%) and IgAN (36.9%) were more common than other glomerular diseases. IgAN (39.4%) was the most common cause of AKI. Sclerosing glomerulonephritis (SGN) (21.1%) was the main cause of progressive chronic kidney disease (CKD).Conclusions: Glomerular diseases in children were related to sex and age. From 1999 to 2019, the spectrum of children's kidney disease in our center changed significantly.

The diagnostic value of immunohistochemical staining of the interstitial vascular C4d complement in membranous nephropathy

Membranous glomerulonephritis (MGN) is the most common cause of adulthood nephrotic syndrome. Diagnosis of membranous nephritis is based on light electron immunofluorescence microscopy and clinical signs. Immune complex deposition against podocyte antigens such as phospholipase A2 receptor (PLA2R) activates the complement system. Of this, complement Component C4d (C4d) is involved in the classical and lectin pathways. This marker may be used by immunohistochemistry to diagnose MGN when other methods are not available. In this work, C4d expression was monitored by immunohistochemical analysis in the glomerular capillaries of patients with primary MGN (study group, N=33) versus patients with minimal change disease (MCD, control group, N=20) in a cross-sectional evaluation performed based on the diagnosis confirmed by light microscopy and immunofluorescence. There was no significant demographic difference between the two groups except for age (P=0.002). C4d immune-expression was positive in glomerular capillary (2+ to 4+) in most of the MGN patients, while it was negative in the MCD group. The sensitivity and specificity of C4d immunostaining were 95% and 100%, respectively. The Pearson correlation coefficient was 0.74 between C4d (immunohistochemistry) and immunoglobulins (IgG; immunofluorescence) and 0.65 between C4d (immunohistochemistry) and the C3 complement product (immunofluorescence). Immunohistochemical evaluation of C4d is, therefore, a sensitive and specific method that has a high correlation with IgG immunofluorescence.

Evaluation of renal biopsies in various kidney diseases with reference to staining

Renal diseases of different origin and nature may produce essentially similar disturbances of renal functions and may have clinical similarities and hence there was a need to classify renal diseases more scientifically. The basic approach was to correlate clinical signs and symptoms with histological changes in the tissue, using both simple and special staining techniques so as to reach to a definitive diagnosis.The present study was conducted on renal biopsy referred to pathology department. Criteria for successful biopsy were as follows-Adequate biopsy sample size, correct processing of specimen, informed interpretation and issue of an accurate report. A total of 29 renal biopsies were examined. In minimal change disease, only in 4 patients the glomerulus was sclerosed. Membranous glomerulonephritis comprised of the maximum number of cases (9/30). Total of 3 cases of renal biopsies revealed amyloidosis. Focal amyloid deposits with deposits either near the hilum or perivascular areas were found in 33.3% of cases, while extensive amyloid deposits were found in 33.3% of the cases.It is necessary to determine both the type of renal disease and the cause of the primary disorder in order to make the diagnosis and various staining techniques play a very helpful role. The likelihood that the biopsy specimen accurately reflects the type and severity of the underlying disease is directly related to both the diffuseness of the disease process and the amount of tissue examined.

P017 Complications of Juvenile Idiopathic Arthritis

Background Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease characterized by onset before the age of 16. This term encompasses several disease categories, each of which has distinct methods of presentation, clinical signs, and prognosis. The study aimed to determine JIA complications in 51 patients. Methods A cross-sectional study including patients diagnosed with JIA according to ILAR criteria was conducted for 26 years [1995– 2021]. Epidemiological, clinical, therapeutic, and evolutive aspects were noted. Results Twenty-nine males and 22 females were included. The mean age of the disease onset was 7.6 years [1,5–16]. The mean age of patients at the time of the study was 23.29 years [9–45]. Polyarticular and seronegative form was the most frequent (34.5%). Other subtypes diagnosed were systemic (25%), enthesitis-related arthritis (21.2%), oligoarticular (12.5%), and seropositive polyarticular (5.8%). Standard X-Ray imaging showed articular damage in 50% of the cases. Hip arthritis was observed in 32% and surgery was needed in 16.9%. One patient presented with atlantoaxial subluxation. Growth retardation was noted in 28.6%. Cardiac manifestations were seen in 3 patients (pericarditis = 2, myocarditis = 1), uveitis in 3 cases, renal manifestation (extra membranous glomerulonephritis) in one patient with polyarticular form. One patient was diagnosed with multiple sclerosis. Small doses of corticosteroids were prescribed in 71.7%. Methotrexate was prescribed in 70.5% (interrupted for adverse effects in 3 patients), sulfasalazine in 30.6%, hydroxychloroquine in 5.7%, leflunomide in 15.4%. bDMARDs were needed in 16 patients: 14 patients received TNF alpha inhibitors, rituximab was prescribed for one patient with a polyarticular form, and tocilizumab in a patient with a systemic form. A switch of bDMARDs was conducted in 10 patients: for inefficiency in 4 cases and adverse effects in other 4 cases. Three patients developed uveitis under Etanercept, septicemia under Adalimumab, an allergic reaction, and depression under Infliximab. One patient died from a convulsive seizure at the age of 9. Conclusion The presence of complications is an additional burden to JIA patients. A multidisciplinary approach is required for the management of these complications.

Glomerular Endothelial Cell-Derived microRNA-192 Regulates Nephronectin Expression in Idiopathic Membranous Glomerulonephritis

BackgroundAutoantibodies binding to podocyte antigens cause idiopathic membranous glomerulonephritis (iMGN). However, it remains elusive how autoantibodies reach the subepithelial space because the glomerular filtration barrier (GFB) is size selective and almost impermeable for antibodies.MethodsKidney biopsies from patients with iMGN, cell culture, zebrafish, and mouse models were used to investigate the role of nephronectin (NPNT) regulating microRNAs (miRs) for the GFB.ResultsGlomerular endothelial cell (GEC)-derived miR-192-5p and podocyte-derived miR-378a-3p are upregulated in urine and glomeruli of patients with iMGN, whereas glomerular NPNT is reduced. Overexpression of miR-192-5p and morpholino-mediated npnt knockdown induced edema, proteinuria, and podocyte effacement similar to podocyte-derived miR-378a-3p in zebrafish. Structural changes of the glomerular basement membrane (GBM) with increased lucidity, splitting, and lamellation, especially of the lamina rara interna, similar to ultrastructural findings seen in advanced stages of iMGN, were found. IgG-size nanoparticles accumulated in lucidity areas of the lamina rara interna and lamina densa of the GBM in npnt-knockdown zebrafish models. Loss of slit diaphragm proteins and severe structural impairment of the GBM were further confirmed in podocyte-specific Npnt knockout mice. GECs downregulate podocyte NPNT by transfer of miR-192-5p–containing exosomes in a paracrine manner.ConclusionsPodocyte NPNT is important for proper glomerular filter function and GBM structure and is regulated by GEC-derived miR-192-5p and podocyte-derived miR-378a-3p. We hypothesize that loss of NPNT in the GBM is an important part of the initial pathophysiology of iMGN and enables autoantigenicity of podocyte antigens and subepithelial immune complex deposition in iMGN.

Quality improvement Initiative to eliminate silver precipitate during Periodic Acid Silver Methenamine Stain (PAMS) automated protocol of renal biopsies at McGill University Health Centre

Introduction/Objective Annually, about 400 renal biopsies are processed at the McGill University Health Centre (MUHC) pathology laboratory located in Montreal, Canada. One of the stains used to visualize the glomerular basement membrane is Periodic Acid Silver Methenamine Stain (PAMS). In August 2020, a strong, granular precipitate of silver was noted during PAMS automated staining resulting in uninterpretable results and delay in the diagnosis. Based on a sample analysis, this problem affected 21 % of kidney biopsies. Methods/Case Report A cause-and-effect workflow was developed for systematic assessment of potential causes of the granular precipitate including pre-analytical and analytical factors. Some of the pre-analytical factors included length of time spent in transport before fixation and patient factors that predisposed precipitate formation. Analytical factors were categorized as fixation problems (temperature, pH, duration), embedding problems (parafilm temperature, cooling method, type of parafilm), slide preparation (temperature, water bath pH, dehydration and further processing steps), microtone parameters (microtone calibration, thickness, laboratory technologist expertise), automatic staining parameters (cartridge age, hematoxylin counterstain duration, wash-out period etc.) and coverslip placement (adhesive type, temperature, drying). Results (if a Case Study enter NA) Following our systematic approach, the cause of granular precipitate was identified as the timing of hematoxylin counterstain. A portion of renal biopsy tissue was taken from parafilm blocks of previouslly reported cases of patients with membranous glomerulonephritis to further test the hypothesis by introduction of various incubation times with the hematoxylin counterstain. Conclusion Best PAMS staining was attained when no hematoxylin counterstain was employed (instead, neutral red counterstain for 70 seconds was used). PAMS staining with hematoxylin counter stain for no more than 60 seconds was found to be acceptable for the interpretation of glomerular pathology.

Membranous Glomerulonephritis: Role of Retinol-Binding Protein in Monitoring and Prognostication

Initially, retinol-binding protein (RBP), was thought to be a biomarker for proximal convoluted tubule dysfunction could be important in chronic kidney diseases (CKD). Membranous glomerulonephritis (MGN) is an important cause of CKD and end-stage renal disease (ESRD). Therefore, monitoring MGN patients using urinary RBP is important in effective treatment decision making and prognostication of MGN patients. Enzyme-linked immunosorbent assay (ELISA) technique was used to detect the RBP in the urine samples of 69 MGN patients comprising 47 primary and 22 secondary MGN, at the end of the follow-up period. The test for the urinary biomarker gave the following results: urinary RBP was detected in 27 (39.1%) and 6 (8.7%) of the primary and secondary MGN patients, respectively. The correlation analysis demonstrated a significant relationship between urinary RBP and renal function test parameters, in addition to a logistic regression analysis that proved urinary RBP as a prognostic non-invasive biomarker for primary MGN. Therefore, urinary RBP could be employed to monitor and provide effective prognosis and early treatment decisions in primary MGN.

Primary membranous glomerulonephritis with negative serum PLA2R in haemophilia A successfully managed with rituximab – case report and review of the literature

Background Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) cause a wide range of glomerular pathologies. In people with haemophilia, transfusion-associated infections with these viruses are common and definitive pathological diagnosis in this population is complicated by the difficulty of safely obtaining a renal biopsy. Membranous nephropathy (MN) is a common cause of adult onset nephrotic syndrome occurring in both primary and secondary forms. Primary MN is associated with podocyte autoantibodies, predominantly against phospholipase A2 receptor (PLA2R). Secondary disease is often associated with viral infection; however, infrequently with HIV or HCV. Distinguishing these entities from each other and other viral glomerular disease is vital as treatment strategies are disparate. Case presentation We present the case of a 48-year-old man with moderate haemophilia A and well-controlled transfusion-associated HCV and HIV coinfection who presented with sudden onset nephrotic range proteinuria. Renal biopsy demonstrated grade two membranous nephropathy with associated negative serum PLA2R testing. Light and electron microscopic appearances were indeterminant of a primary or secondary cause. Given his extremely stable co-morbidities, treatment with rituximab and subsequent angiotensin receptor blockade was initiated for suspected primary MN and the patient had sustained resolution in proteinuria over the following 18 months. Subsequent testing demonstrated PLA2R positive glomerular immunohistochemistry despite multiple negative serum results. Conclusions Pursuing histological diagnosis is important in complex cases of MN as the treatment strategies between primary and secondary vary significantly. Serum PLA2R testing alone may be insufficient in the presence of multiple potential causes of secondary MN.