Kidney Biopsy Specimens Research Articles

Glomeruli Count and Arterial Injury in Real-Time Ultrasound-Guided Needle Kidney Biopsy Specimens: Adequacy of Three Approaches for Pig Kidneys

Introduction: Real-time ultrasound-guided percutaneous kidney biopsy is essential for diagnosis and treatment planning; nonetheless, the optimal puncture approach has yet to be established. In vivo, performing different approaches on the same patient at once is not possible. This study aimed to determine the impact of different approaches on the number of obtained glomeruli and their potential to cause arterial injury using pig kidneys, which are similar to humans. Methods: A total of 120 pig kidneys (60 right-sided kidneys and 60 left-sided kidneys) for research were obtained from a slaughterhouse. The specimens were collected from the lower pole on the sagittal plane of the kidney using three different approaches on the same kidney: caudocranial approach, caudal to cranial; craniocaudal approach, cranial to caudal; and vertical approach, through the surface cortex. Five blinded pediatric nephrologists assessed the number of glomeruli and arterial injuries. Results: Overall, 360 specimens were collected from the kidneys through biopsy using a 16-gauge needle (mean vertical kidney length, 11.2 ± 0.7 cm; mean depth, 3.47 ± 0.23 cm). No significant difference in the incidence of arterial injury was observed between the three approaches (caudocranial vs. craniocaudal vs. vertical approaches: 78% vs. 87% vs. 87%, p = 0.14). In contrast, the vertical approach retrieved significantly more glomeruli than the caudocranial and craniocaudal approaches (caudocranial approach: 7.5 ± 2.8, craniocaudal approach: 7.8 ± 2.7, and vertical approach: 8.9 ± 3.3, p < 0.001). Conclusions: Considering its efficacy and safety profile, the vertical approach may be preferred, as more glomeruli can be obtained without increasing the incidence of arterial injury. Although the results cannot be directly extrapolated to humans due to the differences between species, they still offer important insights into the characteristics of each approach.

ТЕЧЕНИЕ IgA-НЕФРОПАТИИ У ДЕТЕЙ И ОГРАНИЧЕННЫЕ ВОЗМОЖНОСТИ ИММУНОСУПРЕССИВНОЙ ТЕРАПИИ

It is believed that IgA nephropathy (IgAN) in childhood is predominantly manifested by hematuria with episodes of macrohematuria and has a relatively favorable course. The purpose of this research was to analyze the frequency of the use of mycophenolate mofetil (MMF) in children with IgAN in the Nephrology Department of the National Medical Research Center for Children’s Health (Moscow, Russia) and to evaluate the results of treatment in terms of the severity of proteinuria and the presence of a decrease in renal function by glomerular filtration. Materials and methods used: to assess the clinical course, histological features and kidney function during therapy, Authors analyzed the results of 737 biopsies performed in 2018-2022. Results: 126 biopsy specimens with predominant IgA deposition and mesangial proliferation and/or crescents were identified, 20 of them were excluded from further analysis due to the clinical picture of IgA vasculitis. 17 (16% of the remaining 106) patients had nephrotic-level of proteinuria prior to the biopsy, 11 had a history of acute kidney injury and 9 had a persistent decrease in glomerular filtration renal function. Steroid therapy with prednisolone at a dose of 0.5 to 1 mg/kg was carried out in 21 children, 14 (66.7%; CI 45.4-84.1%) of them had relapse or resistance. MMF therapy was started in 16 (11 boys and 5 girls) patients, median age of the therapy initiation was 13.4 [7.9; 15.3] y/o, 6 had a decrease in glomerular filtration rate (GFR) in the range of 64 to 85 ml/min. Kidney biopsy specimens were ere scored according to the Oxford classification MEST-C criteria. During the follow-up period (median 27.6 [20.0; 49.4] months), 14 (88% CI; 66-98) of 16 achieved complete (10) or partial remission, 2 patients had proteinuria of more than 1 g/l. Of 56 patients (median age 13.3 [9.6; 14.9] months) with a follow-up period of more than 6 months, a decrease in GFR was recorded in 5 (31.3%; CI 12.5-55.5) patients on MMF therapy and 4 (22.2%; CI 7.5-44.3) patients who received only a course of steroids and a single one (4.5%; CI 0.3-18.5) who received ACE inhibitor only. Analysis of biopsy results showed an increased risk of reduced GFR in patients with tubular atrophy. Conclusion: MMF therapy may have limited efficacy for proteinuria in IgAN though it does not prevent the GFR decline.

Molecular Signatures of Glomerular Neovascularization in a Patient with Diabetic Kidney Disease.

The Kidney Precision Medicine Project (KPMP) aims to create a kidney tissue atlas, define disease subgroups, and identify critical cells, pathways, and targets for novel therapies through molecular investigation of human kidney biopsies obtained from participants with AKI or CKD. We present the case of a 66-year-old woman with diabetic kidney disease who underwent a protocol KPMP kidney biopsy. Her clinical history included diabetes mellitus complicated by neuropathy and eye disease, increased insulin resistance, hypertension, albuminuria, and relatively preserved glomerular filtration rate (early CKD stage 3a). The patient's histopathology was consistent with diabetic nephropathy and arterial and arteriolar sclerosis. Three-dimensional, immunofluorescence imaging of the kidney biopsy specimen revealed extensive periglomerular neovascularization that was underestimated by standard histopathologic approaches. Spatial transcriptomics was performed to obtain gene expression signatures at discrete areas of the kidney biopsy. Gene expression in the areas of glomerular neovascularization revealed increased expression of genes involved in angiogenic signaling, proliferation, and survival of endothelial cells, as well as new vessel maturation and stability. This molecular correlation provides additional insights into the development of kidney disease in patients with diabetes and spotlights how novel molecular techniques used by the KPMP can supplement and enrich the histopathologic diagnosis obtained from a kidney biopsy.

Can a Single Glomerulus Morphology Implicate Successful Therapy?

Recurrent gross hematuria of glomerular origin is frequently encountered in clinical practice, and in absence of specific serological marker, renal biopsy is mandatory to address the definitive diagnosis, and set out an appropriate therapeutic protocol. Technical deficiencies associated with practice of renal biopsy are frequently encountered, as inadequate number of glomeruli or poor immunofluorescence staining of kidney biopsy specimen; however, these deficiencies can be offset by detailed electron microscopy analysis of a single abnormal glom.We present a single middle-aged Libyan woman, with a rare glomerular disease, related to abnormal activation of alternative complement pathway, where renal biopsy report was initially not adequate and lacking immunohistochemistry workup. However, electron microscopy reports a characteristic abnormal glomerular deposit, coupled with clinical and biochemical data that guided our therapeutic protocol.In a middle-aged female who presented with recurrent gross hematuria and nephrotic range proteinuria, we should suspect a glomerular pathology. Further to immunoglobulin A nephropathy or lupus nephritis, particularly in presence of complement abnormalities and negative serology for glomerulopathy-related autoantibodies, dense deposit disease and C3 glomerulonephritis that are rare complement mediated glomerulopathy should be considered as a seronegative lupus nephritis-equivalent, in terms of their membranoproliferative features on light microscopy, and when setting out appropriate therapeutic protocol. Patient and family counseling for C3 glomerulopathy is essential because this type of glomerulopathy has a recurrence rate after kidney transplant.

#4410 NOVEL DOMINANT ALG5 VARIANT IN TWO UNRELATED FAMILIES WITH LATE-ONSET ADPKD AND ATYPICAL TUBULOINTERSTITIAL CHANGES

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic disorder renowned for its clinical and genetic heterogeneity. Recently, variants in the ALG5 gene have been described as a cause of atypical ADPKD and interstitial fibrosis through the disruption of polycystin 1 maturation and trafficking via underglycosylation. In this report, we investigated genetic cause of the disease in two unrelated Irish families displaying late-onset ADPKD phenotype with atypical tubulointerstitial changes. Method Routine clinical and radiological evaluations were carried out. Available kidney biopsy specimens were reassessed. Genetic testing was performed on probands and all relatives with cystic kidneys. First, a custom-targeted gene panel of 227 genes associated with kidney disease was used, but the causal variant was not identified. Then reading frame-changing variants in variable number tandem repeats region of MUC1 were excluded by single-molecule real-time sequencing. Whole exome sequencing revealed a variant in the ALG5 gene, which is not included in the initial custom gene panel. By targeted Sanger sequencing, segregation of the variant with the disease phenotype was confirmed in both investigated families. Multiple bioinformatic tools were employed to predict the effect on protein structure and functions. Results The clinical diagnosis was consistent in most of the 20 affected individuals with non-enlarged cystic kidneys and few or no liver cysts. All but 1 individual underwent radiological assessment; 7 had kidney and liver cysts, 7 had only kidney cysts, and 5 had no kidney cysts at ages 68.6±14.4, 55.1±15.8, 46.8±15.6 years, respectively. Polycystic liver phenotype (&amp;gt;20 cysts) was present in two individuals. Biopsy-proven extensive kidney interstitial fibrosis and cystic tubular dilation were evident in four affected individuals with available kidney samples. Of the 20 genetically-defined individuals, 4 had end-stage kidney failure at a mean age of 70.25±3.1 years. Ten individuals were CKD stage 3 or greater, while 6 were CKD stage 4 or lower at ages 43.2±12.6 and 63.1±7.5 years (P value 0.004). A novel heterozygous missense variant in the ALG5 gene (NM_013338.5, c.235C&amp;gt;T, p.Arg79Trp) was identified in affected members from investigated families. Genetic screening of 20 affected and 10 unaffected individuals from both pedigrees revealed segregation of the variant with the disease phenotype. The novel ALG5 variant was classified as likely pathogenic as it was absent in the Genome Aggregation Database (gnomAD), is located in a conserved region and is predicted to be deleterious on protein stability. Conclusion This study expands the clinical and genetic spectrum of the identified range of ADPKD, considering the pathogenic ALG5 variants. Establishing a precise diagnosis of atypical cystic and interstitial kidney disease is crucial, with essential implications including follow-up, genetic counselling, prognostication, and therapeutic interventions.

#5591 CIRCULATING ACTIVIN A REFLECTS THE SEVERITY OF RENAL FIBROSIS IN BIOPSY-PROVEN KIDNEY DISEASES—THE TAIPEI RENAL BIOPSY COHORT STUDY

Abstract Background and Aims Despite considerable evidence indicating circulating activin A as a novel renal biomarker, its performance for predicting the severity of renal fibrosis and major adverse renal events (MARE) has not yet been extensively studied. Method We sought to assess the relationship between plasma activin A, renal fibrosis severity, and incidence of MARE in 339 patients undergoing clinically indicated native renal biopsies. To determine the primary source of circulating activin A, RNA-sequencing and histological analyses were performed on kidney biopsy specimens from patients with chronic kidney disease (CKD). We also conducted in vitro experiments to investigate whether inhibiting endogenous activin A could attenuate TGF-β-mediated activation of cultured fibroblasts. Results The median baseline eGFR and proteinuria were 36 mL/min/1.73 m2 and 2.9 mg/mg creatinine, respectively. After multivariable adjustment, elevated plasma activin A was associated with the extent of renal fibrosis. Histological analysis showed increased activin A expression in kidney tissues from patients with CKD, mainly in interstitial myofibroblasts. RNA-sequencing of tubulointerstitial tissue from human biopsy samples also revealed a direct correlation between tissue activin A mRNA expression and plasma activin A levels. During a median follow-up of 22 months, 113 participants suffered MARE. Cox proportional hazards analysis revealed that plasma activin A was associated with higher risk of renal events; however, the association became insignificant after correcting for confounders. Results from in vitro studies demonstrated that knocking down activin A expression could prevent TGF-β-induced activation of NRK49F fibroblasts. Conclusion The findings of this study support activin A as a potential diagnostic and therapeutic target in fibrotic kidney disease.

#4635 CIRCULATING NEPHRIN AUTOANTIBODIES IN PATIENTS WITH POST-TRANSPLANT RECURRENCE OF PRIMARY FOCAL SEGMENTAL GLOMERULOSCLEROSIS

Abstract Background and Aims Post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) is a major challenge in the field of nephrology and kidney transplantation. Primary FSGS is thought to be caused by circulating factors (CFs) that injure podocytes, but these factors remain unknown despite intensive efforts to identify them. Recently, one post-transplant recurrent FSGS patient with pretransplant nephrin autoantibodies was reported (Watts AJB et al, JASN 33:238, 2022). Furthermore, we reported very early post-transplant recurrence changes of podocytes and possible roles of circulating nephrin autoantibodies in a patient with FSGS recurrence (Hattori M et al, AJT 22:2478, 2022). To confirm these preliminary results, we examined the autoantibodies to nephrin and the punctate deposition of IgG colocalized with nephrin using stocked plasma samples and grafted kidney biopsy specimens of the patients with FSGS recurrence. Method This study was approved by the local Ethics Committee of Tokyo Women's Medical University (approval no. 2021-0184). The clinical and research activities reported here are consistent with the Principles of the Declaration of Istanbul as outlined in the “Declaration of Istanbul on Organ Trafficking and Transplant Tourism”. From 1989 to 2022, a total of 78 patients with FSGS underwent kidney transplantation in our institution, and 16 patients experienced post-transplant recurrence of FSGS. Since the stoked plasma samples were available in 14 out of 16 patients, these 14 patients were included in this study. All 14 patients showed immediate post-transplant recurrence and had no pathogenic variants in FSGS-related genes including NPHS1. Circulating anti-nephrin autoantibodies were measured using the ELISA methods based on the Watts's report with one modification, that is, recombinant extracellular domain of human nephrin was obtained commercially (R&amp;D systems, USA). To validate the ELISA system, circulating anti-nephrin autoantibodies were also measured in 9 genetic FSGS patients, 13 membranous nephropathy (MN) patients, 4 lupus nephritis (LN) patients, and 13 healthy controls. Dual immunofluorescence (IF) staining of nephrin and IgG and image acquisition using the two-dimensional structured illumination microscopy mode with a Nikon microscope were performed as previously reported (Hattori M et al, AJT 22:2478, 2022). Results The cut-off level of anti-nephrin antibody calculated from the results of a total 30 cases including 13 MN patients, 4 LN patients, and 13 healthy controls using Frey's formula (J Immunol Method, 1998) was 172.2 U/mL All 14 recurrent patients enrolled in this study had higher titter than the cut-off level and the mean ± SD of the anti-nephrin antibody level in these patients was 939.9 ± 261.8 U/mL. In contrast, the mean anti-nephrin antibody level in patients with genetic FSGS was 98.6 ± 77.3 U/mL, which was comparable with healthy controls. The IF staining of graft biopsy specimens showed punctate depositions of IgG colocalized with nephrin in all 14 recurrent patients. Conclusion The autoantibodies to nephrin in plasma samples and the punctate deposition of IgG colocalized with nephrin in grafted kidney biopsy specimens were observed in all 14 patients with post-transplant recurrent FSGS. Further studies in larger numbers of patients as well as in patients of other ethnicities are clearly required to confirm this surprising result; however, circulating nephrin autoantibodies could be a possible candidate for CFs in the pathogenesis of recurrent FSGS.

#5012 THE EFFECT OF GLOMERULAR C3 DEPOSITION ON RENAL OUTCOME IN PATIENTS WITH MEMBRANOUS NEPHROPATHY: DATA OF THE TSN-GOLD STUDY

Abstract Background and Aims We aimed to evaluate the effect of glomerular C3 deposits on clinical and laboratory findings and outcome in patients with idiopathic membranous nephropathy (MN) included in the Primary Glomerular Diseases Study of Turkish Society of Nephrology Glomerular Diseases Study Group (TSN-GOLD). Method The data of 1595 patients with MN in the database has been evaluated. 114 patients were excluded due to lack of data about C3 staining, 54 patients due to secondary MN and 523 due to lack of data about the follow-up. Patients with glomerular C3 deposits were compared with those with no C3 staining. Results Glomerular C3 deposits were detected in kidney biopsy specimens of 601 patients of the 888 patients analysed. The demographic data, clinical and laboratory findings at the time of diagnosis of C3 (+) and C3 (-) groups are presented in Table 1. They were similar except serum albumin level that was lower in C3 (+) group. Subepithelial deposits and interstitial fibrosis was more prominent, IgG, Kappa and Lambda staining more intense, positivity for C1q and IgA was more frequent in C3 (+) group (Table 2). The study groups were similar regarding remission rates after the first imuunosuppressive treatment (p = 0.582). 155 patients (25.8%) had partial, 152 (25.3%) had complete remission while no remission was detected in 92 patients (15.3%) in C3 (+) group. 69 patients (24.0%) had partial and 81 patients (28.2%) had complete remission; 40 patients (13.9%) had no remission in C3 (-) group. The relapse rates were 17.6% and 19.9% in C3 (+) and C3 (-) groups (p = 0.360). The percentage of patients who died or needed renal replacement therapy (RRT) were higher C3 (+) group (p = 0.013) (Figure 1). Conclusion Need for RRT and mortality is higher in patients with C3 deposition showing the importance of C3 deposition in the prognosis of MN. More prominent interstitial fibrosis may be related with the worse outcome.

Rationale and design of a prospective, clinical study of kidney biopsies in people with type 2 diabetes and severely increased albuminuria (the PRIMETIME 2 study)

IntroductionDiabetic kidney disease is a severe complication of diabetes. The diagnosis is based on clinical characteristics such as persistently elevated albuminuria, hypertension and decline in kidney function, although this definition...

Evidence of kidney injury in preeclampsia: Increased maternal and urinary levels of NGAL and KIM-1 and their enhanced expression in proximal tubule epithelial cells.

Proteinuria and glomerular endotheliosis are characteristics of glomerular injury in preeclampsia, a hypertensive disorder in human pregnancy. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are biomarkers of acute/chronic renal tubule injury. To determine if tubule injury occurs in preeclampsia, we determined maternal plasma and urine NGAL and KIM-1 levels and evaluated NGAL and KIM-1 expression in kidney biopsy specimens from women with preeclampsia. Prenatal and postpartum maternal blood and urinary samples were collected from three groups of pregnant women: normal pregnancy (n = 100), preeclampsia (n = 83), and pregnancy complicated with chronic hypertension (n = 20). Plasma and urine levels of NGAL and KIM-1 were measured by ELISA. Kidney biopsy tissue sections from patients with preeclampsia (n = 5) were obtained from Pathology Archives and processed to determine NGAL and KIM-1 expression by immunostaining and high kidney solution images were assessed by electron microscopy (EM). Prenatal plasma and urine levels of NGAL and KIM-1 were significantly higher in preeclamptic than in normal controls, p < 0.01. In normal pregnancy, both plasma and urine levels of NGAL and KIM-1 at 24-48 h after delivery and 6-8 weeks postpartum were relatively comparable to that of antenatal levels. In preeclampsia, urine, but not plasma, NGAL levels were reduced at 6-8 weeks postpartum compared to the antenatal levels, p < 0.05. Although maternal and urine KIM-1 levels were reduced at 6-8 weeks postpartum compared to the antenatal levels in preeclampsia, the levels were still higher than those in normal pregnancy. Positive expression of NGAL and KIM-1 was detected in proximal tubule epithelial cells in kidney tissue specimens from preeclampsia but not in non-pregnancy controls. EM examination showed glomerular and tubular injury in preeclampsia. Our findings of increased maternal levels and urine secretion of NGAL and KIM-1, along with the upregulation of NGAL and KIM-1 expression in tubular epithelial cells in preeclampsia, provide plausible evidence that tubular injury exists in preeclampsia. The higher postpartum NGAL and KIM-1 levels in preeclamptic pregnancies indicate that tubular injury would not resolve within 2-3 months after delivery and suggest that proper follow-up and management of kidney function in women with preeclampsia would be necessary to reduce chronic kidney diseases in those women later in life.

Bupi Yishen formula may prevent kidney fibrosis by modulating fatty acid metabolism in renal tubules

BackgroundBupi Yishen formula (BYF), a traditional Chinese herbal mixture, has demonstrated better effectiveness than Losartan in preserving renal function and preventing composite severe adverse outcomes in patients with advanced chronic kidney disease (CKD) in a recent randomized controlled trial. Prior studies have shown that BYF exerts anti-inflammatory and anti-fibrotic effects in the kidneys of CKD models, but the underlying mechanisms have not been fully elucidated. PurposeThe aim of this study was to investigate the protective effects of BYF administration on profibrotic phenotypic changes in the kidney and to elucidate its fundamental mechanisms of action. MethodsAdenine and 5/6 nephrectomy rat models were administered with two doses of BYF extract (15 or 30 g/kg/d) by intragastric administration, and Losartan treatment was used as a positive control group. The relationship between BYF renoprotection and restoration of fatty acid dysregulation was examined using the two fibrosis models and TGFb1-induced human tubular HK2 cells. Transcriptomic profiles of the fibrotic kidneys obtained from adenine-induced CKD rats were used to identify the key mechanisms that are affected by BYF intervention. Human relevance and clinical implications were established by re-analysis of the microarray databases of CKD patients and immunostaining on human biopsy specimens. ResultsBYF effectively prevented kidney histological damage and ameliorated renal malfunction in the adenine rat model of CKD. BYF robustly attenuated the significant increase in profibrotic and proapoptotic markers in fibrotic kidneys of adenine-induced CKD rats. Transcriptomic analyses of the fibrotic kidneys of the adenine rats identified fatty acid metabolism as the key dysregulated pathway affected by BYF prevention. BYF significantly reversed defective fatty acid oxidation (FAO) and the intracellular lipids accumulation in the fibrotic kidneys induced by 5/6 nephrectomy. Furthermore, BYF prevented dysfunctional fatty acid metabolism, which were associated with the significant improvement of TGFb1-induced profibrotic changes in HK2 human proximal tubular cells. Furthermore, analyses of kidney microarray databases and biopsy specimens of CKD patients suggested that FAO defect is common in CKD in humans. ConclusionOur exploratory study found that BYF may exert protective effects on renal fibrosis by regulating the fatty acid metabolism of renal tubular cells, which may be a key mechanism for preventing kidney fibrosis in CKD.

Crescentic glomerulonephritis in children: A retrospective review of data from Chris Hani Baragwanath Academic Hospital

Background. Crescentic glomerulonephritis (CGN) as a cause of progressive renal failure is rare. Crescent formation on kidney biopsyrepresents a response to injury of the glomerular capillary walls. There are limited published reports on paediatric CGN in Africa.Objectives. To describe the clinical presentation and outcome of children with CGN in Soweto, South Africa, over a 22-year period.Methods. A retrospective study was conducted at the Paediatric Renal Unit at Chris Hani Baragwanath Academic Hospital. Childrenyounger than 14 years with crescent formation in more than 50% of glomeruli on renal biopsy were included in the study. Kidney biopsy specimens were examined by light microscopy, immunofluorescence and electron microscopy. Demographic and clinical data were extracted from the patient files.Results. During the study period, 961 kidney biopsies were performed. Fourteen patients (1.5%) met inclusion criteria of crescents in&gt;50% of glomeruli. Common clinical findings were oedema (n=13; 93%), microscopic haematuria (n=12; 86%), hypertension (n=11; 79%)and proteinuria (n=10; 71%). The median estimated glomerular filtration rate (eGFR) at presentation was 23.9 mL/min/1.73m2. Thirteen patients (93%) had immune-complex-mediated glomerulonephritis. The underlying cause was acute post-infectious glomerulonephritis in 9 patients (64%), membranoproliferative glomerulonephritis and IgA nephropathy in 2 patients each (14%) and global sclerosis in 1 patient (7%). Prolonged duration of symptoms resulted in a lower eGFR at follow-up. Treatment included peritoneal dialysis, methylprednisolone and cyclophosphamide. Seven (54%) patients had a normal eGFR at a median (range) follow-up of 36.7 (4.5 - 61.5) months. Six (46%) patients had progressed to chronic kidney disease stages 2 - 5. One patient was followed up for less than 3 months, and therefore was not included in the follow-up results.Conclusion. Poor outcomes were observed in patients who presented late. The clinical findings of haematuria, hypertension and acutekidney injury warrant early referral and kidney biopsy to determine management.

Identification of AGXT2, SHMT1, and ACO2 as important biomarkers of acute kidney injury by WGCNA.

Acute kidney injury (AKI) is a serious and frequently observed disease associated with high morbidity and mortality. Weighted gene co-expression network analysis (WGCNA) is a research method that converts the relationship between tens of thousands of genes and phenotypes into the association between several gene sets and phenotypes. We screened potential target genes related to AKI through WGCNA to provide a reference for the diagnosis and treatment of AKI. Key biomolecules of AKI were investigated based on transcriptome analysis. RNA sequencing data from 39 kidney biopsy specimens of AKI patients and 9 normal subjects were downloaded from the GEO database. By WGCNA, the top 20% of mRNAs with the largest variance in the data matrix were used to construct a gene co-expression network with a p-value < 0.01 as a screening condition, showing that the blue module was most closely associated with AKI. Thirty-two candidate biomarker genes were screened according to the threshold values of |MM|≥0.86 and |GS|≥0.4, and PPI and enrichment analyses were performed. The top three genes with the most connected nodes, alanine-glyoxylate aminotransferase 2(AGXT2), serine hydroxymethyltransferase 1(SHMT1) and aconitase 2(ACO2), were selected as the central genes based on the PPI network. A rat AKI model was constructed, and the mRNA and protein expression levels of the central genes in the model and control groups were verified by PCR and immunohistochemistry experiments. The results showed that the relative mRNA expression and protein levels of AGXT2, SHMT1 and ACO2 showed a decrease in the model group. In conclusion, we inferred that there is a close association between AGXT2, SHMT1 and ACO2 genes and the development of AKI, and the down-regulation of their expression levels may induce AKI.

618 - Feasibility and utility of intraprocedural kidney biopsy specimen adequacy verification with a portable digital microscope

618 - Feasibility and utility of intraprocedural kidney biopsy specimen adequacy verification with a portable digital microscope

Kidney involvement of chronic active Epstein-Barr virus infection.

A 54-year-old Japanese woman presented with a fever of unknown origin and renal dysfunction. She had experienced intermittent fever for 10 years, but the frequency increased to a constant fever. Her renal function had gradually deteriorated over the past year, and serum creatinine and urinary α1-microglobulin levels were elevated to 2.23 mg/dL and 113 mg/L, respectively. Physical and laboratory examinations were unremarkable, except for mild anemia and elevated serum creatinine levels. Analysis of peripheral blood lymphocyte subsets showed 59% CD3, 35% CD4 and 31% CD8. Epstein-Barr virus (EBV) serology showed elevated levels of EBV capsid antigen IgG and EBV nuclear antigen (1:1280 and 1:40, respectively). Plasma EBV-DNA level was 5.63 log IU/mL, and an oligoclonal band was detected by Southern blot hybridization of EBV terminal repeat analysis. Quantification of EBV-DNA in peripheral lymphocyte subset using magnetic beads showed that EBV predominantly resided in CD4+ T-cells. (CD4, 258,768; CD8, 27,738; and CD56, 23,369; IU/µgDNA, respectively). T-cell receptor α gene rearrangement was undetected. Based on the above, she was diagnosed with chronic active EBV infection (CAEBV). 18F-fluorodeoxyglucose positron emission tomography/computerized tomography showed bilateral kidney enlargement and mildly enhanced uptake (maximum standardized uptake value 4.08 g/mL) (Figure 1 top left). Kidney biopsy specimen stained with hematoxylin and eosin showed diffuse tubulointerstitial infiltration of small to medium-sized lymphocytes in the renal parenchyma (Figure 1 top right). Massive infiltration of CD4+ T-cells was documented by immunohistochemical staining (Figure 1 bottom left). Furthermore, EBV-infected cells were detected by in situ hybridization with EBV-encoded RNA (EBER) (Figure 1 bottom right). Immunostaining of EBV nuclear antigen-2 and latent membrane protein 1 were negative. EBER-positive cells were distributed in the same region as CD4+ T-cells, consistent with the predominant presence of EBV-DNA in CD4+ T-cells. Her renal function had improved after initiating chemotherapy, and she is scheduled for hematopoietic stem cell transplantation. The clinical features of EBV infection vary according to the type of EBV-infected cells. The predominant EBV-infected cells in EBV-induced hemophagocytic lymphohistiocytosis are CD8+ T cells, whereas in CAEBV, CD4+ T cells are predominantly infected. Although rare, renal invasion of EBV should be considered in cases with renal impairment, and its clinical significance needs to be investigated. AF and SS wrote and edited the manuscript, provided patient care and reviewed the literature. KS and MT provided patient care. TS and KM wrote and edited the manuscript. All authors reviewed and approved the final version of the manuscript We thank Dr. Yuka Torii (Department of Pediatrics, Nagoya University, Japan) for quantification of the EBV viral load of lymphocyte subsets using magnetic beads. We also thank Dr. Hiroshi Kimura (Department of Virology, Nagoya University, Japan) for his helpful advice on patient care. We appreciate the staff of the Department of Hematology, Kameda Medical Center for providing patient care. We thank Editage (www.editage.jp) for English language editing. The authors declare they have no conflicts of interest. The authors received no specific funding for this work. This study was conducted according to the Declaration of Helsinki, and written consent was obtained from the patient for this report. The patient provided written informed consent for the publication of this case, with the removal of all identifying information to ensure anonymity and maintain privacy. The data that support the findings of this study are available from the corresponding author upon reasonable request. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The Clinical Profile and Long-Term Outcome of Children with Membranous Nephropathy, and the Evaluation of Anti-Phospholipase A2 Receptor Antibody Immunohistochemistry in Kidney Biopsy.

Idiopathic membranous nephropathy (iMN) is a rare cause of nephrotic syndrome in children (1%-7%). Anti-phospholipase A2 receptor (PLA2R) antibody positivity in kidney biopsy is observed in 52%-78% of adults and 45% of children with iMN. The objectives of the study are to analyze the clinical profile and outcome of membranous nephropathy in children, to assess the prevalence of anti-PLA2R immunohistochemistry (IHC) in kidney biopsy, and to correlate their presence with disease characteristics. We are reporting a single-center retrospective study conducted in pediatric nephrology division. Clinical data and outcome parameters of children with membranous nephropathy were analyzed. PLA2R IHC was performed in kidney biopsy specimens retrospectively. We analyzed 43 children with membranous nephropathy (MN) from a single center. 18 (42%) had idiopathic MN (iMN). PLA2R IHC was performed in kidney biopsy specimens in 14/18 (78%) patients with iMN and 7/9 (78%) non-lupus secondary membranous nephropathy (SMN) patients. The most common cause of SMN was lupus nephritis in 16 patients (64%). The mean estimated glomerular filtration rate (eGFR) at onset was 156 ± 81 ml/min/1.73m2. The sensitivity and specificity of PLA2R IHC in diagnosing pediatric MN was 50% and 57%, respectively; positive and negative predictive values were 70% and 36%, respectively. At the final follow-up, chronic kidney disease stage 5 (CKD 5) developed in 2/14 (14.3%) iMN patients. IHC PLA2R staining of glomerular tissue is a useful diagnostic marker of IMN. Though PLA2R prevalence is lower in children, its role in guiding treatment needs further exploration.

Oxalate Nephropathy.

Oxalate Nephropathy.

Lupus nephritis as a specific clinical and immunological phenotype of systemic lupus erythematosus

Lupus nephritis (LN) is the leading cause of death in systemic lupus erythematosus (SLE), so its early detection and treatment is of utmost importance. Features of the onset, clinical signs, certain morphological classes, as well as more aggressive therapy make it possible to assign SLE with LN to a distinct disease phenotype.Objective: to characterize the clinical, immunological and morphological features of the SLE phenotype with a predominant kidney involvement based on a comparative analysis of patients with LN and without LN.Patients and methods. The study included 400 patients with SLE who met the 2012 SLICC criteria and were hospitalized to V.A. Nasonova Research Institute of Rheumatology from 2013 to 2021. The diagnosis of LN was established in 192 (48%) patients, of which in 82 (43%) it was confirmed by pathological study of kidney biopsy specimens (the SLE group with LN). In 208 (52%) patients, no kidney damage was observed, and they constituted the SLE group without LN.All patients underwent a standard examination with an assessment of disease activity according to the SLEDAI-2K index, irreversible changes in organs according to the SLICC damage index, immunological disorders, clinical and biochemical blood tests, urinalysis according to unified methods, glomerular filtration rate, as well as pathological examination of kidney biopsy specimens for confirmation of LN in the presence of an appropriate clinical picture. In patients of both groups, a comparative study of the main clinical, laboratory, immunological manifestations of SLE, the features of the disease onset, its first clinical signs, possible trigger factors, and the drugs used was carried out.Results and discussion. In the LN group, insolation was more likely to trigger the development of SLE than in the group without LN (respectively, in 26% and 13% of cases; p=0.007). In turn, SLE without kidney damage more often than SLE with LN debuted during pregnancy or after childbirth.The first signs of the disease in almost 40% of patients with LN were proteinuria and/or changes in urinary sediment, edema, increased blood pressure, the development of LN in some cases was preceded by polyarthritis or combined lesions of the skin and joints, but no later than 6 months, signs of kidney damage appeared. In the SLE group without LN, polyarthritis (in 33%), combined lesions of the skin and joints (in 26%), and Raynaud's syndrome (in 16%; p &lt;0.0001) were more often observed at the onset. In patients with LN, erythematous lesions of the facial skin ("butterfly", in 42%), serositis (exudative pleuritis — in 44%, pericarditis — in 46%, ascites and hydrothorax — in 5%; p&lt;0.0001), as well as hematological disorders such as anemia (in 63%), leukopenia (in 49%) and thrombocytopenia (in 42%) were present more frequently. With the development of LN, an acute course and high activity of the disease occurred significantly more often. In the study of immunological parameters in the group without LN, lupus anticoagulant (in 6%) and antibodies to SS-A/Ro and SS-B/La (in 18 and 9% of patients, respectively) were detected significantly more often, while in the LN group — hypocomplementemia (in 81%; p&lt;0.0001). Therapy also differed significantly: patients with LN received higher doses of glucocorticoids (p&lt;0.0001), mycophenolate mofetil, and cyclophosphamide.Conclusion. SLE with LN can be considered a distinct disease phenotype with a set of characteristics (clinical and laboratory parameters, response to therapy, prognosis) that distinguish it from other SLE variants.

Histopathological patterns in kidney biopsies in Zimbabwe: a 12-year retrospective study

Objectives: Data on histological patterns in native kidney biopsies in Zimbabwe is sparse. We sought to describe these histological patterns over a 12 year period.&#x0D; Study Design: We retrospectively evaluated the histological patterns on kidney biopsies at the largest private pathology laboratory in Zimbabwe from 1 January 2008 to 31 January 2020.&#x0D; Setting: Histopathological data on all percutaneous native kidney biopsy specimens received at the pathology lab was recovered from electronic records. Indications for the kidney biopsy were then reviewed and patient demographics collected.&#x0D; Subjects: All patients who had a histopathological report identified from the electronic records and who had had a kidney biopsy for nephrological indications were included.&#x0D; Results: Sixty four 64 reports in total were identified and 18 were excluded (17biopsies done to evaluate renal masses and 1 kidney transplant biopsy). Thus 46 percutaneous native kidney biopsies were evaluated in the final analysis. Ninety six percent of the patients biopsied were of African descent. Primary FSGS was the commonest primary glomerular disease (26%) and lupus nephritis the commonest secondary glomerular disease (24%). The commonest indication for kidney biopsy was nephrotic syndrome (61%).&#x0D; Conclusions: FSGS was the commonest primary GN in this study of adult patients and the commonest indication for kidney biopsy was nephrotic syndrome. This finding is useful for guiding clinicians on managing patients presenting with nephrotic syndrome in low resource settings as often patients lack access to kidney biopsy services and empiric use of steroids may be considered in appropriate individual cases.

Roxadustat (FG-4592) protects against ischaemia-induced acute kidney injury via improving CD73 and decreasing AIM2 inflammasome activation.

Hypoxia-mediated inflammation plays a crucial role in renal ischaemia-reperfusion (IR)-induced acute kidney injury (AKI) and may influence renal graft survival, with no available pharmacological treatments. Here we investigate the protective effects and mechanism of roxadustat (FG-4592), a hypoxia-inducible factor stabilizer, against renal IR injury. The protein expression levels of CD73 and AIM2 inflammasome complex were examined in kidney biopsy specimens of AKI and post-renal transplantation (PRT) patients. The effects of FG-4592 on CD73 and absent in melanoma 2 (AIM2) inflammasome components were examined in IR mice (right nephrectomy, followed by 30min of unilateral renal ischaemia and reperfusion for 24h), and some of the model mice received intraperitoneal administrations of adenosine 5'-(α,β-methylene)diphosphate sodium salt, which is an inhibitor of CD73. The function of FG-4592 was also investigated in vitro with HK-2 cells. In the AKI and PRT patients, the protein expression of AIM2 complex [AIM2-apoptosis-associated speck-like protein (ASC)-cleaved caspase-1) increased and the activation of CD73 signalling pathway was detected as well. The pretreatment of FG-4592 improved the creatinine elevation and renal tubular injuries induced by ischaemia. What's more, the administration of FG-4592 significantly enhanced CD73 synthesis in mouse kidney but suppressed the activation of the AIM2 inflammasome [decreased AIM2, ASC, caspase-1, interleukin (IL)-1β and IL-18 levels]. Notably, the renoprotection of FG-4592 and the inhibition of AIM2 were abolished by the CD73 inhibitor. FG-4592-conveyed protection against AKI might be mediated by the induction of CD73 and the suppression of the AIM2 inflammasome, which may provide a novel therapeutic method for the treatment of AKI.