Sclerotic Glomeruli Research Articles

MO261: Sparsentan, The Dual Endothelin Angiotensin Receptor Antagonist (DEARA), Attenuates Albuminuria and Protects from the Development of Renal Injury to a Greater Extent Than Losartan in the GDDY Mouse Model of IGA Nephropathy: A 16-Week Study

Abstract BACKGROUND AND AIMS gddY mice are an IgA nephropathy (IgAN)-prone mouse model that develops albuminuria by 8 weeks (wks) of age with glomerular IgA, IgG and C3 deposits and progressive mesangioproliferative glomerulonephritis. We have previously shown that sparsentan (SP), a novel, highly selective, first-in-class, single-molecule dual endothelin angiotensin receptor antagonist (DEARA) being developed for the treatment of focal segmental glomerulosclerosis and IgAN, protected gddY mice from the development of albuminuria and glomerulosclerosis in an 8-week study. Here we compare the impact of SP and losartan (LS), an angiotensin II subtype 1 receptor antagonist (AT1R), on albuminuria, % of sclerotic glomeruli (GS), podocyte number, and glycocalyx damage in gddY mice treated for 16 weeks. METHOD gddY mice at 4 weeks of age were treated for 8 or 16 weeks either with chow as a control (C) (n = 10) or containing SP at 900 ppm (SP900) (n = 12) or with control chow and LS in drinking water to deliver 30 mg/kg of LS (LS30) (n = 12). Systolic blood pressure (BP) was measured by tail-cuff plethysmography at 8, 12 and 18 weeks of age. Albuminuria/creatinine ratio (ACR) was assessed every 2 weeks until 20 weeks of age. Kidney biopsies (n = 4–5 per group) were taken from a subset of mice sacrificed at age 12 weeks and at the end of the study at 20 weeks of age (5–7 per group) and processed for determination of GS, the number of podocytes assessed by immunohistochemistry using an anti-WT-1 antibody (30 glomeruli per animal), and measurement of the glycocalyx area using FITC-labeled lectin (10 glomeruli per animal). RESULTS gddY mice treated with SP900 or LS30 had an equivalent and significant (P < .01) reduction in BP compared with C mice at 12 and 18 weeks of age (18 weeks of age mean BP ± SD mmHg: C, 147 ± 28; SP900, 100 ± 6; LS30, 101 ± 8). Despite similar systemic hemodynamic effects, SP900 treatment resulted in a greater and more rapid reduction in ACR from baseline compared with either mice treated with C or LS30 during the first 4 weeks of treatment (Fig. 1). Development of GS was significantly attenuated in mice at 20 weeks of age treated with SP900 (P < .001) compared with C mice, but not in those treated with LS30 (mean sclerosis score ± SD: C, 28 ± 17; SP900, 3 ± 1; LS30, 19 ± 21). Compared with C mice at 20 weeks of age, SP900 (P < .0001) and LS30 (P < .05) significantly prevented the reduction in WT-1 immunoreactivity (WT-1 positive cells/glomerulus, mean ± SD: C, 7.3 ± 0.5; SP900, 10.0 ± 0.5; LS30 8.1 ± 0.8). Notably, SP900-treated mice had significantly greater WT-1 staining (P < .0001) and glycocalyx area (Fig. 2) than LS30 mice. CONCLUSION gddY mice treated from 4–20 weeks of age with sparsentan demonstrated a more rapid attenuation of ACR and greater protection from GS than mice treated with losartan. Sparsentan protected the glomeruli from loss of podocytes and glycocalyx to a greater extent than losartan despite equivalent lowering of BP. These results suggest that the ability of sparsentan to protect gddY mice from progression of IgAN nephropathy may go beyond effects mediated through reduction in blood pressure and antagonism of AT1R alone and may be attributed to its dual mechanism of action. If translated to the clinic, these data may support sparsentan as a new approach to the treatment of IgAN.

Computational Integration of Renal Histology and Urinary Proteomics using Neural Networks.

Histological image data and molecular profiles provide context into renal condition. Often, a biopsy is drawn to diagnose or monitor a suspected kidney problem. However, molecular profiles can go beyond a pathologist's ability to see and diagnose. Using AI, we computationally incorporated urinary proteomic profiles with microstructural morphology from renal biopsy to investigate new and existing molecular links to image phenotypes. We studied whole slide images of periodic acid-Schiff stained renal biopsies from 56 DN patients matched with 2,038 proteins measured from each patient's urine. Using Seurat, we identified differentially expressed proteins in patients that developed end-stage renal disease within 2 years of biopsy. Glomeruli, globally sclerotic glomeruli, and tubules were segmented from WSI using our previously published HAIL pipeline. For each glomerulus, 315 handcrafted digital image features were measured, and for tubules, 207 features. We trained fully connected networks to predict urinary protein measurements that were differentially expressed between patients who did/ did not progress to ESRD within 2 years of biopsy. The input to this network was either glomerular or tubular histomorphological features in biopsy. Trained network weights were used as a proxy to rank which morphological features correlated most highly with specific urinary proteins. We identified significant image feature-protein pairs by ranking network weights by magnitude. We also looked at which features on average were most significant in predicting proteins. For both glomeruli and tubules, RGB color values and variance in PAS+ areas (specifically basement membrane for tubules) were, on average, more predictive of molecular profiles than other features. There is a strong connection between molecular profile and image phenotype, which can be elucidated through computational methods. These discovered links can provide insight to disease pathways, and discover new factors contributing to incidence and progression.

Parietal epithelial cells maintain the epithelial cell continuum forming Bowman's space in focal segmental glomerulosclerosis.

ABSTRACTIn the glomerulus, Bowman's space is formed by a continuum of glomerular epithelial cells. In focal segmental glomerulosclerosis (FSGS), glomeruli show segmental scarring, a result of activated parietal epithelial cells (PECs) invading the glomerular tuft. The segmental scars interrupt the epithelial continuum. However, non-sclerotic segments seem to be preserved even in glomeruli with advanced lesions. We studied the histology of the segmental pattern in Munich Wistar Frömter rats, a model for secondary FSGS. Our results showed that matrix layers lined with PECs cover the sclerotic lesions. These PECs formed contacts with podocytes of the uninvolved tuft segments, restoring the epithelial continuum. Formed Bowman's spaces were still connected to the tubular system. In biopsies of patients with secondary FSGS, we also detected matrix layers formed by PECs, separating the uninvolved from the sclerotic glomerular segments. PECs have a major role in the formation of glomerulosclerosis; we show here that in FSGS they also restore the glomerular epithelial cell continuum that surrounds Bowman's space. This process may be beneficial and indispensable for glomerular filtration in the uninvolved segments of sclerotic glomeruli.

Holistic fine-grained global glomerulosclerosis characterization: from detection to unbalanced classification.

Purpose: Recent studies have demonstrated the diagnostic and prognostic values of global glomerulosclerosis (GGS) in IgA nephropathy, aging, and end-stage renal disease. However, the fine-grained quantitative analysis of multiple GGS subtypes (e.g., obsolescent, solidified, and disappearing glomerulosclerosis) is typically a resource extensive manual process. Very few automatic methods, if any, have been developed to bridge this gap for such analytics. We present a holistic pipeline to quantify GGS (with both detection and classification) from a whole slide image in a fully automatic manner. In addition, we conduct the fine-grained classification for the subtypes of GGS. Our study releases the open-source quantitative analytical tool for fine-grained GGS characterization while tackling the technical challenges in unbalanced classification and integrating detection and classification. Approach: We present a deep learning-based framework to perform fine-grained detection and classification of GGS, with a hierarchical two-stage design. Moreover, we incorporate the state-of-the-art transfer learning techniques to achieve a more generalizable deep learning model for tackling the imbalanced distribution of our dataset. This way, we build a highly efficient WSI-to-results GGS characterization pipeline. Meanwhile, we investigated the largest fine-grained GGS cohort as of yet with 11,462 glomeruli and 10,619 nonglomeruli, which include 7841 globally sclerotic glomeruli of three distinct categories. With these data, we apply deep learning techniques to achieve (1) fine-grained GGS characterization, (2) GGS versus non-GGS classification, and (3) improved glomeruli detection results. Results: For fine-grained GGS characterization, when pretrained on the larger dataset, our model can achieve a 0.778-macro- score, compared to a 0.746-macro- score when using the regular ImageNet-pretrained weights. On the external dataset, our best model achieves an area under the curve (AUC) score of 0.994 when tasked with differentiating GGS from normal glomeruli. Using our dataset, we are able to build algorithms that allow for fine-grained classification of glomeruli lesions and are robust to distribution shifts. Conclusion: Our study showed that the proposed methods consistently improve the detection and fine-grained classification performance through both cross validation and external validation. Our code and pretrained models have been released for public use at https://github.com/luyuzhe111/glomeruli.

Automatic Evaluation of Histological Prognostic Factors Using Two Consecutive Convolutional Neural Networks on Kidney Samples.

The prognosis of patients undergoing kidney tumor resection or kidney donation is linked to many histologic criteria. These criteria notably include glomerular density, glomerular volume, vascular luminal stenosis, and severity of interstitial fibrosis/tubular atrophy. Automated measurements through a deep-learning approach could save time and provide more precise data. This work aimed to develop a free tool to automatically obtain kidney histologic prognostic features. In total, 241 samples of healthy kidney tissue were split into three independent cohorts. The "Training" cohort (n=65) was used to train two convolutional neural networks: one to detect the cortex and a second to segment the kidney structures. The "Test" cohort (n=50) assessed their performance by comparing manually outlined regions of interest to predicted ones. The "Application" cohort (n=126) compared prognostic histologic data obtained manually or through the algorithm on the basis of the combination of the two convolutional neural networks. In the Test cohort, the networks isolated the cortex and segmented the elements of interest with good performances (>90% of the cortex, healthy tubules, glomeruli, and even globally sclerotic glomeruli were detected). In the Application cohort, the expected and predicted prognostic data were significantly correlated. The correlation coefficients r were 0.85 for glomerular volume, 0.51 for glomerular density, 0.75 for interstitial fibrosis, 0.71 for tubular atrophy, and 0.73 for vascular intimal thickness, respectively. The algorithm had a good ability to predict significant (>25%) tubular atrophy and interstitial fibrosis level (receiver operator characteristic curve with an area under the curve, 0.92 and 0.91, respectively) or a significant vascular luminal stenosis (>50%) (area under the curve, 0.85). This freely available tool enables the automated segmentation of kidney tissue to obtain prognostic histologic data in a fast, objective, reliable, and reproducible way.

Identification of glomerulosclerosis using IBM Watson and shallow neural networks.

BackgroundAdvanced stages of different renal diseases feature glomerular sclerosis at a histological level which is observed by light microscopy on tissue samples obtained by performing a kidney biopsy. Computer-aided diagnosis (CAD) systems leverage the potential of artificial intelligence (AI) in healthcare to support physicians in the diagnostic process.MethodsWe propose a novel CAD system that processes histological images and discriminates between sclerotic and non-sclerotic glomeruli. To this goal, we designed, tested, and compared two artificial neural network (ANN) classifiers. The former implements a shallow ANN classifying hand-crafted features extracted from Regions of Interest (ROIs) by means of image-processing procedures. The latter, instead, employs the IBM Watson Visual Recognition System, which uses a deep artificial neural network making decisions taking the images as input, without the need to design any procedure for describing images with features. The input dataset consisted of 428 sclerotic glomeruli and 2344 non-sclerotic glomeruli derived from images of kidney biopsies scanned by the Aperio ScanScope System.ResultsBoth AI approaches allowed to very accurately distinguish (mean MCC 0.95 and mean Accuracy 0.99) between sclerotic and non-sclerotic glomeruli. Although the systems may seem interchangeable, the approach based on feature extraction and classification would allow clinicians to gain information on the most discriminating features. In fact, further procedures could explain the classifier’s decision by analysing which subset of features impacted the most on the final decision.ConclusionsWe developed a customizable support system that can facilitate the work of renal pathologists both in clinical and research settings.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s40620-021-01200-0.

Deep learning segmentation of glomeruli on kidney donor frozen sections.

Purpose: Recent advances in computational image analysis offer the opportunity to develop automatic quantification of histologic parameters as aid tools for practicing pathologists. We aim to develop deep learning (DL) models to quantify nonsclerotic and sclerotic glomeruli on frozen sections from donor kidney biopsies. Approach: A total of 258 whole slide images (WSI) from cadaveric donor kidney biopsies performed at our institution ( ) and at external institutions ( ) were used in this study. WSIs from our institution were divided at the patient level into training and validation datasets (ratio: 0.8:0.2), and external WSIs were used as an independent testing dataset. Nonsclerotic ( ) and sclerotic ( ) glomeruli were manually annotated by study pathologists on all WSIs. A nine-layer convolutional neural network based on the common U-Net architecture was developed and tested for the segmentation of nonsclerotic and sclerotic glomeruli. DL-derived, manual segmentation, and reported glomerular count (standard of care) were compared. Results: The average Dice similarity coefficient testing was 0.90 and 0.83. And the , recall, and precision scores were 0.93, 0.96, and 0.90, and 0.87, 0.93, and 0.81, for nonsclerotic and sclerotic glomeruli, respectively. DL-derived and manual segmentation-derived glomerular counts were comparable, but statistically different from reported glomerular count. Conclusions: DL segmentation is a feasible and robust approach for automatic quantification of glomeruli. We represent the first step toward new protocols for the evaluation of donor kidney biopsies.

Assessment of renal glomerulosclerosis and thickness of the carotid intima-media complex as a means of age estimation in Western European bodies

IntroductionThe estimation of age-at-death of unidentified cadavers is a central aspect of the identification process. With increasing age, the incidence of glomerulosclerosis and the thickness of the carotid wall have been observed to also increase. This correlation has been demonstrated in various international histological studies. The aim of our study was to assess whether these correlations also apply to a Western European population.MethodologyIn this retrospective observational study, kidney and common carotid artery samples from 216 cases autopsied at the Institute of Legal Medicine at the Justus-Liebig University in Giessen, Germany, were examined. Only cases with available tissue samples from both body sides were included. Exclusion criteria were poor sample quality and an age younger than 21 years. After histological processing, the tissue samples were assessed and digitally evaluated. Regression and classification analyses were used to investigate the correlation between age-at-death and intima-media thickness and age-at-death and the incidence of renal glomerular sclerosis.ResultsOf the 216 autopsy cases, 183 were included for evaluation. Analysis of the carotid artery segments showed a strong correlation (Pearson correlation coefficient r = 0.887) between the intima-media-complex thickness and chronological age. Classification of the glomerulosclerotic incidence showed a correlation of 37.7–43.1% with the predicted age group.DiscussionBoth the intima-media thickness and the proportion of sclerotic glomeruli can be used to estimate age in Western European cadavers. On the basis of these results, both methods are suited to supplement other already established methods for age-at-death estimation in the identification of an unknown cadaver.

A study on the relationship between morphological lesions of lupus nephritis with demographic and biochemical findings

Introduction: Lupus nephritis is one of the important aspects of systemic lupus erythematosus (SLE). Objectives: This study aimed to investigate possible relationship between pathological lesions of lupus nephritis classes and demographic and biochemical findings among patients. Patients and Methods: This is a cross-sectional study that was conducted on a group of renal biopsy proven lupus nephritis patients using lupus nephritis classification of ISN/RPS 2003. We collected demographic data of all patients including age, gender serum creatinine and 24h proteinuria. Results: Data of 101 patients, of whom 78 (77.23%) were females and mean age of 33.54±13.15 years. The mean serum creatinine and proteinuria were 1.54±0.88 mg/dL 2502.5±1495.05 mg/d. Based on our data, IV-G (class IV, diffuse lupus nephritis-global) lupus nephritis class was the most common (39.6%) followed by class III (23.8%). The mean crescent and sclerotic glomeruli were 1.66±3.32 and 2.27±5.32, respectively. In this study, 24 hours proteinuria, serum creatinine, activity percent, chronicity percent, crescent and glomerular sclerosis between genders showed no significant differences (P>0.05). The correlation between plasma creatinine and activity was directly positive and significant (r=0.381, P=0.001). In addition, a significant correlation between C1q deposits and glomerular sclerosis (P=0.031) was detected. Accordingly, a significant correlation between IgG deposits and lupus nephritis classification (P=0.025) was seen. Conclusion: Lupus nephritis of IV-G and III classes of lupus nephritis were most common among patients and higher IgG deposits were observed in patients with IV-G classification. We found a significant correlation between glomerular sclerosis and C1q deposits that could be an indicator of lupus nephritis activity and severity. However, we recommend further studies in this regard.

Glomerular Size in Transplanted Kidneys: Does Size Matter?

Glomerular Size in Transplanted Kidneys: Does Size Matter?

Clinicopathological Characteristics and Influencing Factors of Renal Vascular Lesions in Anti-neutrophil Cytoplasmic Autoantibody-Related Renal Vasculitis.

The purpose of this study was to evaluate the clinicopathological features of different degrees of extraglomerular renal vascular lesions (RVLs) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated renal vasculitis and explore their clinical determinants. This is a retrospective study of 186 patients with ANCA-associated renal vasculitis diagnosed at the First Affiliated Hospital of Zhengzhou University from January 2014 to April 2019. The patients who met the inclusion criteria were divided into non-renal RVLs, mild RVLs, moderate RVLs, and severe RVLs. It was found that there were significant differences in serum creatinine (SCR), estimated glomerular filtration rate (eGFR), erythrocyte sedimentation rate (ESR), high-density lipoprotein (HDL), systolic blood pressure (SBP), the prevalence rate of hypertension, the proportion of normal glomeruli, and the proportion of sclerotic glomeruli and interstitial fibrosis integral. SCR and ESR are independent risk factors for RVLs. The participants were followed up for 1 year, and the progression to end-stage renal disease (ESRD) and death was defined as endpoint events. We found that the survival rate of patients without RVLs was significantly higher than that of patients with RVLs and that the RVLs were an independent risk factor for ESRD or death. Early intervention in the progression of RVLs can improve the prognosis.

A kidney discard decision strategy based on zero-time histology analysis could lead to an unjustified increase in the organ turndown rate among ECD.

The utility of zero-time kidney biopsies (KB) in deciding to accept expanded criteria donor (ECD) kidneys remains controversial. However, zero-time histology is one of the main causes for discarding kidneys in the United States. In a single-centre study, we examined the utility and impact on outcome of the use of frozen section zero-time KB among ECD. Ninety-two zero-time KB were analysed for accept/discard decision between 2005 and 2015 among ECD. 53% of kidneys were rejected after zero-time KB analysis; there was no difference in individual clinical and biological data between accepted/rejected groups. However, histology of rejected kidneys showed more sclerotic glomeruli (20% vs. 8%; P<0.001), increased interstitial fibrosis (1.25±0.12 vs. 0.47±0.09; P<0.0001), more arteriosclerosis (2.14±0.17 vs. 1.71±0.11; P=0.0032) and arteriolar hyalinosis (2.15±0.12 vs. 1.55±0.11; P=0.0006). Using propensity score matching, we generated a group of 42 kidney allograft recipients who received a transplant matched for donor zero-time histology and clinical characteristics with donors whose kidneys were rejected. Interestingly, their 1- and 5-year graft survival and function were similar to the global cohort of ECD recipients. In conclusion, when performed, zero-time KB was a decisive element for kidney discard decision. However, adverse zero-time histology was not associated with poorer graft survival and kidney function among ECD.

Possible implication of intermolecular epitope spreading in the production of anti-glomerular basement membrane antibody in anti-neutrophil cytoplasmic antibody-associated vasculitis.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is sometimes complicated by anti-glomerular basement membrane (GBM) disease. Proteases, including elastase, released from neutrophils activated by ANCA are implicated in the pathogenesis of AAV. Epitopes of anti-GBM antibody exist in the α3-subunit non-collagenous (NC1) domain of collagen type IV [Col (IV)]. This region, called α3(IV)NC1, is structurally cryptic. This study aimed to determine the production mechanism of anti-GBM antibody in AAV. We first examined whether α3(IV)NC1 could be revealed by the digestion of formalin-fixed, paraffin-embedded (FFPE) normal kidney sections and Col (IV) by proteases, including neutrophil elastase, using immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA). Next, the reveal of α3(IV)NC1 and the infiltration of CD11c+ macrophages in the affected kidneys were evaluated by IHC and immunofluorescent staining using FFPE sections. Finally, the production of anti-GBM antibody in AAV rats was determined by ELISA. α3(IV)NC1 was revealed by the digestion of FFPE normal kidney sections and Col (IV) by proteases. Although the reveal of α3(IV)NC1 was observed in sclerotic glomeruli regardless of causative diseases, CD11c+ macrophages near α3(IV)NC1 were characteristics of AAV. Anti-GBM antibody was produced subsequent to ANCA in some AAV rats. IHC demonstrated the reveal of α3(IV)NC1 in affected renal tissues and the infiltration of CD11c+ macrophages around the sites. The collective findings suggest that, in AAV, proteases released from neutrophils activated by ANCA digest Col (IV) and result in the reveal of α3(IV)NC1, CD11c+ macrophages present GBM epitopes, and then the host's immune system produce anti-GBM antibody.

MO080HISTOLOGIC CLASSIFICATION OF ANCA-ASSOCIATED GLOMERULONEPHRITIS – ARE THERE OTHER MORPHOLOGICAL FEATURES THAT CAN BETTER DESCRIBE MIXED GROUP?

Abstract Background and Aims In 2010 a new histopatological classification for ANCA-associated GN (ANCA GN) was developed – the Berden classification. It is composed of four categories – focal, crescentic, sclerotic and mixed - based on the predominance (≥50%) of normal glomeruli, cellular crescents, and globally sclerotic glomeruli, respectively. The mixed category, related to an intermediate renal outcome, has no glomerular feature predominating. Our aim was to evaluate other histopathological characteristics that could be significant in the mixed group and their impact on survival and renal outcome. Method This is a multi-center retrospective observational study which included patients with ANCA GN who were submitted to kidney biopsy at the time of clinical diagnosis, between 2013 and 2018. Several histopathological data were analysed, including percentage of cellular, fibrocellular and fibrous crescents; presence of fibrinoid necrosis, interstitial hemorrhage, tubular atrophy ant interstitial fibrosis. Clinical data such as need of dialysis at presentation and death, during a 2 year follow up period, were also examined. The patients were classified accordingly to the histopathological Berden classification. For statistical analysis purposes they were divided in two groups: mixed and non-mixed. Categorical variables are presented as frequencies and percentages, continuous variables as means and standard deviations, or medians and interquartile ranges (IQR) for variables with skewed distributions. Statistical analysis was performed using SPSS version 25 for Windows. Results We observed 51 ANCA GN kidney biopsies: 68.5% (n=35) from mixed, 11.8% (n=6) from crescentic and sclerotic and 7.8% (n=4) from focal category. In average, the biopsies contained 10.4±4.8 glomeruli. The percentage of fibrous crescents was significantly higher in mixed than non-mixed group (16.1±18.6% vs 7.2±17.9%; p=0.037). Although not statistically significant, the percentage of fibrocellular crescents was higher (10.3±20.9 vs 6.2±12.5; p=0.512) and the percentage of cellular crescents was lower (15.4±18.2 vs 34.3±37.7; p=0.072) in mixed group. The presence of fibrinoid necrosis (54.3% vs 87.5%; p=0.021) and fibrinoid necrosis with cellular crescents (34.3% vs 68.8%; p=0.022) were both lower in mixed category. There was no difference in the need of dialysis at presentation between both groups, but the percentage of fibrous crescents was a predictor of dialysis induction at admission in all cases [p=0.009; adjusted odds ratio (OR) 1.053 (CI: 1.013–1.096)]. Deaths were significantly higher in mixed group (34.3% vs 6.3%; p=0.033). Conclusion There are other morphological aspects that seem to be relevant in the characterization of different histological classes of ANCA GN. Having more chronic lesions, like the percentage of fibrous crescents, and a less frequency of acute lesions, such as fibrinoid necrosis, proved to be relevant in the mixed group and may be associated to the higher mortality in this class. Besides, the percentage of fibrous crescents was itself a predictor of the need of dialysis, which highlights the importance of assess other characteristics, in addition to those included in the current ANCA GN classification. However, further studies and larger samples are needed to evaluate better the importance of other morphological features in this classification and their influence on survival and renal outcome of these patients.

MO303URINARY ALBUMIN-TO-CREATININE RATIO INDICATES NECROTIZING AND CRESCENTIC GLOMERULONEPHRITIS IN ANCA-ASSOCIATED VASCULITIS

Abstract Background and Aims Renal involvement is a common and severe complication of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) as it can cause acute kidney injury (AKI), end-stage renal disease (ESRD) or death. We have previously reported that elevated urinary albumin-to-creatinine ratio (uACR) correlates with rapid deterioration of kidney function in ANCA GN. Therefore, we here aimed to describe the association between proteinuric findings and histopathological diagnosis of necrotizing and crescentic ANCA GN in 50 urinary samples at admission and corresponding renal biopsies of patients with AAV. Method A total number of 50 urinary samples at admission and corresponding renal biopsies with confirmed renal involvement of AAV were retrospectively included between 2015 till 2020 in a single-center observational study. Results Renal involvement of AAV revealed variable proteinuria ranging from low-range to nephrotic syndromes, however most patients presented with subnephrotic proteinuria predominated by albumin (uACR). Severely increased uACR levels &amp;gt;300 mg/g correlated with reduction of normal glomeruli (P&amp;lt;0.001), attributed to increased glomerular crescents (P&amp;lt;0.001) and necrosis (P=0.008). By contrast, no such association was observed for global sclerotic glomeruli (P=0.58), revealing that uACR reflects necrotizing and crescentic ANCA GN rather than adaptive glomerular hyperfilitration in chronic sclerosing stage. These findings were additionnaly bolstered by histopathological subgrouping and ARRS: patients with uACR levels &amp;gt;300 mg/g were classified either into Berden’s crescentic class (P=0.002) or ANCA renal risk score (ARRS) high/intermediate risk (P=0.003). No association between uACR levels and extrarenal manifestation of AAV disease could be observered, suggesting that uACR levels reflected specific renal involvement with ANCA GN and further confirmed by survival analysis for cumulative incidence of RRT during the short-term course of disease. In summary, uACR measurements at admission were associated with renal biopsy findings thereafter. Levels of uACR &amp;gt;300 mg/g were more frequently observed in necrotizing and crescentic ANCA GN with classification either into Berden’s crescentic class or ARRS high/intermediate risk and specific for renal involvement in AAV. Conclusion Early identification of patients who mostly benefit from aggressive immunosuppressive therapy is of clinical importance. Our observation that uACR levels at disease onset predict necrotizing and crescentic ANCA GN requires further investigation for therapeutic decision especially in patients with severe deterioration of kidney function.

MO259LYMPHOPENIA AT ANCA-GLOMERULONEPHRITIS DIAGNOSIS IS CORRELATED WITH SEVERITY AND RENAL PROGNOSIS

Abstract Background and Aims Lymphopenia is commonly observed in various autoimmune diseases, such as systemic lupus erythematosus, where it has been associated with disease activity or prognosis. However, in ANCA-associated vasculitis (AAV) only few, small-scale studies have been targeted to this issue. Research has not yet focused on ANCA-glomerulonephritis (ANCA-GN) patients. Thus, the aim of this study was to analyze the association between lymphocyte counts and outcomes in a large cohort of ANCA-GN patients. Method We used the Maine-Anjou AAV registry that retrospectively gathers data on consecutive patients affected by AAV in four French Nephrology Centers, recorded since January 2000. We analyzed clinical, biological, and histological data at diagnosis of ANCA-GN. Biological data, including lymphocyte counts, were collected before the administration of any immunosuppressive treatment. Risk factors for end-stage kidney disease (ESKD) were analyzed. Event-free survival was also assessed. Results Among the 145 patients included in the study, 53 (37%) patients presented with lymphopenia at ANCA-GN diagnosis. Lymphopenic patients were older (72 [63–79] vs 66 [56–73] years old, p = 0.010), had a lower renal function at baseline (eGFR 13 mL/min vs 26 mL/min, p = 0.002), and a higher proteinuria (1.86 [1.21–3.52] g/g vs 1.30 [0.75–2.65] g/g, p = 0.042). There was a trend for a higher BVAS (18 [14–22] vs 15 [12–20], p = 0.076) in lymphopenic patients. Therapeutic management between the two groups was similar. There was no difference in relapse rate between the two groups but lymphopenic patients were more likely to require kidney replacement therapy (51% vs 25%, p = 0.003) and were more likely to die (34% vs 17%, p = 0.039). Lymphopenia was correlated with histological lesions and especially with the percentage of sclerotic glomeruli (p = 0.0027). ESKD-free survival and overall survival were lower in lymphopenic patients (p &amp;lt; 0.0001 and 0.0051 respectively). In multivariate Cox analysis, lymphopenia, but not death, was an independent risk factor for ESKD (HR 4.47 (95% confidence interval: [2.06–9.72], p &amp;lt; 0.001). Conclusion Lymphopenia correlates with severity of ANCA-GN at diagnosis and predicts poor renal outcome. In this view, lymphopenia could be used as a simple and cost-effective biomarker to assess renal prognosis at ANCA-GN diagnosis.

Total Nephron Number and Single-Nephron Parameters in Patients with IgA Nephropathy.

Single-nephron dynamics in progressive IgA nephropathy (IgAN) have not been studied. We applied novel methodology to explore single-nephron parameters in IgAN. Nonglobally sclerotic glomeruli (NSG) and globally sclerotic glomeruli (GSG) per kidney were estimated using cortical volume assessment via unenhanced computed tomography and biopsy-based stereology. Estimated single-nephron GFR (eSNGFR) and single-nephron urine protein excretion (SNUPE) were calculated by dividing eGFR and UPE by the number of NSG. Associations with CKD stage and clinicopathologic findings were cross-sectionally investigated. This study included 245 patients with IgAN (mean age 43 years, 62% male, 45% on renin-angiotensin aldosterone system [RAAS] inhibitors prebiopsy) evaluated at kidney biopsy. CKD stages were 10% CKD1, 43% CKD2, 19% CKD3a, 14% CKD3b, and 14% CKD4-5. With advancing CKD stage, NSG decreased from mean 992,000 to 300,000 per kidney, whereas GSG increased from median 64,000 to 202,000 per kidney. In multivariable models, advancing CKD stage associated with lower numbers of NSG, higher numbers of GSG, and lower numbers of GSG + NSG, indicating potential resorption of sclerosed glomeruli. In contrast to the higher mean glomerular volume and markedly elevated SNUPE in advanced CKD, the eSNGFR was largely unaffected by CKD stage. Lower SNGFR associated with Oxford scores for endocapillary hypercellularity and crescents, whereas higher SNUPE associated with segmental glomerulosclerosis and tubulointerstitial scarring. SNUPE emerged as a sensitive biomarker of advancing IgAN. The failure of eSNGFR to increase in response to reduced number of functioning nephrons suggests limited capacity for compensatory hyperfiltration by diseased glomeruli with intrinsic lesions.

Lymphopaenia at diagnosis of anti-neutrophil cytoplasmic antibody-vasculitis with renal involvement is correlated with severity and renal prognosis.

Lymphopaenia is commonly observed in autoimmune diseases, where it has been associated with disease activity or prognosis. However, in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) only a few small-scale studies have been targeted towards this issue. Research has not yet focused on AAV with renal involvement (AAV-RI). Thus the aim of this study was to analyse the association between lymphocyte counts and outcomes in a large cohort of AAV-RI patients. We used the Maine-Anjou AAV registry that retrospectively gathers data on consecutive patients affected by AAV in four French nephrology centres, recorded since January 2000. We analysed clinical, biological and histological data at diagnosis of AAV-RI. Risk factors for end-stage kidney disease (ESKD) were analysed. Event-free survival was also assessed. Among the 145 patients included in the study, those with lymphopaenia at diagnosis had a lower renal function at baseline [estimated glomerular filtration rate (eGFR) 13 versus 26 mL/min; P = 0.002] and were more likely to require kidney replacement therapy (51% versus 25%; P = 0.003). Lymphopaenia was correlated with histological lesions and especially with the percentage of sclerotic glomeruli (P = 0.0027). ESKD-free survival was lower in lymphopaenic patients (P < 0.0001). In multivariate Cox analysis, lymphopaenia was an independent risk factor for ESKD [hazard ratio 4.47 (95% confidence interval 2.06-9.72), P < 0.001]. Lymphopaenia correlates with the severity of AAV glomerulonephritis at diagnosis and predicts poor renal outcome. In this view, lymphopaenia could be used as a simple and cost-effective biomarker to assess renal prognosis at AAV-RI diagnosis.

Étiologies et facteurs pronostiques des néphropathies interstitielles aiguës

IntroductionAcute interstitial nephritis represents a clinically and etiologically heterogeneous group of kidney diseases. The aim of our study was to explore the main causes of biopsy-proven acute interstitial nephritis and to identify predictive factors of renal outcome. MethodsWe conducted a retrospective monocentric study which included patients with biopsy proven AIN, followed in our department during the period between 1980 and 2018. The non-recovery of kidney function or an estimated glomerular filtration rate˂60 mL/min/1.73 m2 were considered as a worse renal outcome. ResultsA total of 65 acute interstitial nephritis patients were enrolled. The mean age of patients was 41.3±16 years with a female predominance (78%). Drug-induced etiology was the most common (29%). The most frequent culprit drugs in our study were NSAID followed by antibiotics. The renal prognosis was unfavorable in 21 cases (32%). The independent predictive factors for renal outcome were : a percentage of sclerotic glomeruli greater than 15% (P=0.004), absence of interstitial edema (P˂0.001), non-use to corticosteroid therapy (P=0.02) and a delay in initiating corticosteroid therapy greater than 21 days (P=0.02). ConclusionDrugs currently represent the most common cause of acute interstitial nephritis. The renal prognosis is often favorable, but the progression can be towards chronic renal failure in the event of diagnostic and therapeutic delay. Our data suggest a beneficial influence of steroids on the outcome of acute interstitial nephritis.

Primary membranoproliferative glomerulonephritis in Sfax, Tunisia: epidemiologic profile and prognostic factors

Introductionmembranoproliferative glomerulo nephritis (MPGN) is a rare kidney disease with a poor prognosis as 50% of patients attend the end stage renal failure after 10 years of follow up. Several factors have been described associated with poor renal prognosis. The aim of our study is to determine the epidemiologic profile and to identify prognostic factors of MPGN.Methodsour study is retrospective over a period of 16 years (January 1996 - December 2011) including all cases of primary MPGN aged more than 15 years, collected at the nephrology department of Hedi Chaker University Hospital, Sfax, Tunisia.Resultswe collected 118 cases of primary MPGN, with mean age of 45 (SD 19) years. The incidence of MPGN has decreased from 10 cases/year between 1996 and 1999 to 5 cases/year between 2008 and 2011. Seventy-nine percent of patients (n=93) had renal failure at the moment of diagnosis (e-GFR less than 60 ml/min/1.73m2;). After a mean follow-up of 51.9 (SD 44) months, progression to end stage renal failure was observed in 43.5% of followed cases (n=20). On univariate analysis, factors associated with death or progression to end stage renal failure were initial renal failure and sclerotic glomeruli (respectively p at 0.040 and 0.032). Multivariate analysis indicated that initial renal failure was significantly correlated with death or progression to end stage renal failure (HR: 0.14, 95% CI (0.033-0.593), p=0.008).Conclusionthere has been a decline in the number of cases of MPGN diagnosed in our hospital. The presence of renal failure at diagnosis was associated with death or progression to end stage renal failure.