Segmental Sclerosis Research Articles

Association between ATG16L1 rs2241880(T300A) and rs4663421 and ANCA‑associated vasculitis in the Guangxi population of China: Propensity score matching analysis.

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a rare autoimmune disease with an unclear pathogenesis. The present study investigated the associations between autophagy-related protein 16-like 1 (ATG16L1) rs2241880(T300A) and rs4663421 and AAV. A total of 177 patients with AAV and 216 healthy controls were included. Propensity score matching was used to match the two groups of subjects in terms of sex, age and ethnicity. Analyses of the relationships between these genetic polymorphisms and AAV susceptibility, including comparisons of allele and genotype frequency distribution, linkage disequilibrium analysis and analysis of single nucleotide polymorphism (SNP) interactions between two loci were performed. The association between the loci and laboratory test results and renal pathology were also analysed. A total of 154 pairs of patients with AAV and healthy controls was successfully matched. Neither polymorphism was associated with AAV susceptibility. However, SNP interaction in the model constructed with the two loci was statistically significant (P=0.018), and the combination of the AA genotype of rs2241880(T300A) and GG genotype of rs4663421 was associated the highest disease risk. The differences in the Birmingham Vasculitis Activity Score (BVAS), C-reactive protein (CRP) levels and 24-h urine protein level between patients with the rs2241880(T300A) AA + AG genotypes and the GG genotype were statistically significant (P<0.05). Furthermore, significant differences in the severity of glomerulosclerosis and global sclerosis were detected between individuals with the AA + AG genotype and those with the GG genotype at the rs2241880(T300A) locus (P<0.05). Similarly, there were statistically significant differences in degree of segmental sclerosis between individuals with CC + CG genotypes and those with GG genotypes at the rs2243421 locus (P<0.05). In summary, the single gene polymorphisms of these loci were not associated with genetic susceptibility to AAV. However, SNP interactions may serve a role in the risk of AAV. The rs2241880(T300A) polymorphism may be associated with BVAS, CRP levels and 24-h urine protein level in AAV. These SNPs may be associated with glomerulosclerosis and segmental sclerosis.

Anti-nephrin autoantibodies: novel predictors of post-transplant recurrence of focal segmental glomerular sclerosis.

Post-transplant recurrence of focal segmental glomerular sclerosis (FSGS) is a major challenge in the field of kidney transplantation. Currently, the most reliable predictor of FSGS recurrence is disease recurrence in a previous allograft. Recent studies suggest a possible causal role of anti-nephrin autoantibodies in the primary disease (primary FSGS and minimal change disease), as well as post-transplant recurrence of FSGS. In this issue of Kidney International, Batal etal. evaluate pretransplant anti-nephrin autoantibodies as a specific predictor of FSGS recurrence and demonstrate colocalization of nephrin and punctate IgG in anti-nephrin-positive patients with disease recurrence.

Histologic Predictors of Response and Prognosis in Lupus Nephritis: Why Segmental Sclerosis Should Not Be Part of the Chronicity Index

Histologic Predictors of Response and Prognosis in Lupus Nephritis: Why Segmental Sclerosis Should Not Be Part of the Chronicity Index

Correlation Analysis between Extracapillary Hypercellularity, Segmental Sclerosis, and Clinical Features of Diabetic Nephropathy

Correlation Analysis between Extracapillary Hypercellularity, Segmental Sclerosis, and Clinical Features of Diabetic Nephropathy

Clinical analysis of sirolimus therapy in children with refractory nephrotic syndrome

To investigate the clinical efficacy of sirolimus in treating children with refractory nephrotic syndrome, the clinical data for 22 children from the Children's Hospital of Hebei Province were analyzed retrospectively. There were 16 boys and six girls, and the treatment period was from September 2015 to April 2021. There were two patients with steroid-dependent nephrotic syndrome (SDNS), six patients with frequently relapsing nephrotic syndrome (FRNS), and 14 patients with steroid-resistant nephrotic syndrome (SRNS). All patients were defined as having refractory nephrotic syndrome. There were 12 patients (including nine SRNS patients and three FRNS patients) with minimal change disease (MCD), three patients (three SRNS patients) with focal segmental glomerular sclerosis (FSGS), one FRNS patient with mesangial proliferative glomerulonephritis (MsPGN), and six patients without a kidney biopsy. Compared with levels before sirolimus treatment, 24-hour urine protein (24-h UP), low-density lipoprotein cholesterol (LDL-C), urea (Ur) and serum creatinine (SCr) levels were significantly lower (all p < 0.05). Moreover, albumin (Alb) was significantly increased (p < 0.05), and there were no significant differences in total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), immunoglobulin A (IgA), immunoglobulin G (IgG) or immunoglobulin M (IgM) (all p > 0.05) at the first follow-up. Sirolimus is effective as the first treatment of some children with refractory nephrotic syndrome, but its long-term efficacy and adverse reactions still require follow-up.

Tubulointerstitial nephropathy is the predominant finding in men in a review of more than 3000 renal biopsies over a 10-year period from Sri Lanka

BackgroundChronic kidney disease (CKD) is a significant clinical challenge in Sri Lanka. The present study presents histopathological diagnoses from native renal biopsies in Kandy District, 2011–2020.MethodsReports of 5,014 renal biopsies principally performed at Kandy Teaching Hospital over 2011–2020 were reviewed. After exclusions for post-kidney transplant biopsies (1,572) and those without evident pathology (347), 3,095 biopsies were included. The predominant histopathological entities were grouped and categorised according to diagnosis and stratified by age and sex.ResultsThe main histopathological entities (all biopsies) were tubulointerstitial nephropathy (TIN) 25% (n = 760), glomerulonephritis (GN) 15% (467), lupus nephropathy 14% (429), focal segmental glomerular sclerosis (FSGS) 10% (297), and IgA nephropathy (IgAN) 8% (242). For adult women ≥ 15 years, the main histopathological entities were lupus nephropathy 24% (325), TIN 17% (228), and GN 16% (217). For adult men ≥ 15 years, the main histopathological entities were TIN 34% (449), GN 14% (180), and IgAN 10% (125). The proportion of TIN in the present study was higher than international studies of a similar size.ConclusionThis is the largest study of renal biopsies reported from Sri Lanka to date. TIN was the most common diagnosis in adults ≥ 15 years at 25%. Notable sex differences showed TIN was the most common histopathology in men (34%) but not in women (17%). No previously published similar study of this size has found TIN as the predominant diagnosis amongst renal biopsies in men. Further research is required into the possible causes of these observations in Sri Lanka.Clinical Trial Number.Not applicable.

Postpartum Renal Cortical Necrosis: A Case Series

Rationale & ObjectivePostpartum renal cortical necrosis (postpartum RCN) is a severe form of obstetric acute kidney injury. This study aimed to identify clinicopathological features in Chinese postpartum RCN cases to determine how pathologic findings may contribute to the treatment and prognosis. Study DesignSingle-center, case series Setting & ParticipantsTwelve patients with postpartum RCN had kidney biopsies at Peking University First Hospital between 2014 and 2021. The diagnosis of postpartum RCN was made according to typical MRI or pathological features. Clinical, laboratory and pathological data were compared between patients with eGFR <30 (poor outcome) and ≥30 ml/min/1.73 m2 after six months. ObservationsAll postpartum RCN patients presented with stage 3 AKI attributed to a probable atypical hemolytic uremic syndrome. Pregnancy terminations occurred at a median gestational age of 35.5 weeks. Kidney biopsy was performed ranging 18 days to 4 months from delivery. Upon biopsy, hemoglobin, platelet count and LDH levels had been restored to 137 g/L, 214 ×109/L and 231.50±65.01 U/L, respectively. Four patients exhibited poor outcome, demonstrating higher schistocyte count, serum creatinine and mean arterial pressure at onset. Pathologically, glomerular segmental sclerosis was prevalent. The NOS variant was the most common type, followed by collapsing variant, cellular variant, and tip variant. Patients with poor kidney outcome had more glomerular coagulative necrosis, capillary thrombosis, extensive cortical coagulative necrosis, and pronounced arteriole/artery lesions including increased interlobular arteriole intimal edema and fibrin thrombosis, but a lower occurrence of segmental sclerosis. LimitationsLimited sample size and retrospective design. ConclusionsOur research has identified key pathological features in postpartum RCN patients with aHUS, highlighting the necessity for more effective therapeutic options. There is a clear demand for non-invasive biomarkers that can accurately track disease progression and inform treatment duration for long-term outcomes improvement.

Clinical and genetic analysis of a child with Focal segmental glomerulosclerosis due to a novel variant of PLCE1 gene

To explore the genetic basis and clinical phenotype of a Chinese pedigree affected with Focal segmental glomerulosclerosis (FSGS). A male patient who was admitted to the First Affiliated Hospital of Zhengzhou University on July 26, 2018 was selected as the study subject. Clinical data of the patient was collected. Next generation sequencing and Sanger sequencing were carried out to detect the variant sites. Bioinformatic software was used to simulate the effect of candidate variant on the protein functions. Ultrasound exam of the patient showed enhanced echo for the renal parenchyma. Kidney biopsy had confirmed the pathological diagnosis of FSGS (non-specific). Electronic microscopy displayed segmental sclerosis of the glomeruli, mild hyperplasia of mesangial cells and matrix. The proband was found to harbor two novel variants of the PLCE1 gene, namely c.3199delA (p.N1067Mfs*15) and c.4441_4443delATC (p.1481_1481del), which were respectively inherited from his mother and father. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rated as pathogenic (PVS1+PM2_Supporting+PP3; PM2_Supporting+PM3+PP3). Bioinformatic simulation suggested that both variants could significantly affect the tertiary structure of the PLCE1 protein. The c.4441_4443delATC and c.3199delA variants of the PLCE1 gene probably underlay the pathogenesis of the FSGS in this pedigree.

Immunosuppressant-resistant nephrotic syndrome and primary amenorrhea: A case report of adult Frasier syndrome and literature review.

We present a case of a 19-year-old who developed nephrotic syndrome with preserved renal function. Renal biopsy confirmed focal segmental glomerular sclerosis (FSGS). No remission was achieved despite 2 years of treatment with glucocorticoids, mycophenolate mofetil, tacrolimus, and cyclophosphamide. After transfer to our center, we performed re-examination of renal pathology by electron microscope (EM), chromosomal karyotype, and gene analysis. EM revealed uneven thickness of the glomerular basement membrane without obvious stratification or fracture. Gene analysis revealed a splice mutation (1447+1G>A) in IVS9 and chromosomal karyotype was (46, XY), confirming the diagnosis of Frasier syndrome, which was consistent with primary amenorrhea overlooked by local nephrologists. Cyclosporin A was prescribed to reduce the proteinuria, but serum creatinine increased to 152 μmol/L.

Differentiated metabolomic profiling reveals plasma amino acid signatures for primary glomerular disease

Primary glomerular disease (PGD) is an idiopathic cause of renal glomerular lesions that is characterized by proteinuria or hematuria and is the leading cause of chronic kidney disease (CKD). The identification of circulating biomarkers for the diagnosis of PGD requires a thorough understanding of the metabolic defects involved. In this study, ultra-high performance liquid chromatography–tandem mass spectrometry was performed to characterize the amino acid (AA) profiles of patients with pathologically diagnosed PGD, including minimal change disease (MCD), focal segmental glomerular sclerosis (FSGS), membranous nephropathy, and immunoglobulin A nephropathy. The plasma concentrations of asparagine and ornithine were low, and that of aspartic acid was high, in patients with all the pathologic types of PGD, compared to healthy controls. Two distinct diagnostic models were generated using the differential plasma AA profiles using logistic regression and receiver operating characteristic analyses, with areas under the curves of 1.000 and accuracies up to 100.0% in patients with MCD and FSGS. In conclusion, the progression of PGD is associated with alterations in AA profiles, The present findings provide a theoretical basis for the use of AAs as a non-invasive, real-time, rapid, and simple biomarker for the diagnosis of various pathologic types of PGD.

Idiopathic membranous nephropathy with focal segmental sclerosis

To evaluate the clinical and pathological features and prognosis of idiopathic membranous nephropathy (IMN) with focal segmental sclerosis (FSGS) in a group of Russian patients. 101 patients with morphologically verified IMN were enrolled in our single-center cohort retrospective study. The patients were divided into IMN group and IMN+FSGS group. The primary and secondary outcomes were analyzed in 59 patients, which had follow-up data for period more than 6 months. At the time of renal biopsy the median age was 46.0 (33.0; 55.0) years and the median follow-up was 6.8 (4.0; 15.6) months. Secondary FSGS was revealed in 15 (14.9%) patients with IMN. The IMN and IMN+FSGS groups did not differ in gender, age of onset IMN and age of renal biopsy. In the IMN+FSGS group proteinuria was higher and estimated glomerular filtration rate was lower than that in the IMN group (p<0.05). The systolic arterial pressure and creatinine levels in the IMN+FSGS group were slightly higher than in the IMN group, but the difference was not significant. Anti-PLA2R positivity was similar in both groups. Chronic kidney disease (CKD) progression was observed in 10/52 (19.2%) and 5/7 (71.4%) patients in IMN and IMN+FSGS groups, respectively. In a multivariate Cox regression model, age of renal biopsy (odds ratio - OR 1.12, 95% confidence interval - CI 1.03-1.22; р=0.07), FSGS (OR 0.05, 95% CI 0.01-0.34; р=0.002) и response to initial course of immunosuppression (OR 0.33, 95% CI 0.12-0.95; р=0.039) were associated with the CKD progression. In patients with IMN secondary FSGS is associated with a greater severity of proteinuria and a decrease in estimated glomerular filtration rate, and is also an independent factor of the CKD progression.

Astragaloside IV Protects Against Podocyte Injury by Upregulating Mitophagy via the Mfn2/Pink1/Parkin Axis.

Podocyte injury is the most important pathological hallmark of kidney diseases. Autophagy is a critical factor that involves podocyte injury. Here, we sought to determine whether Astragaloside IV (AS-IV) was able to improve renal function and reverse podocyte injury through the regulation of autophagy. Using the Adriamycin (ADR) mice model, cultured immortalized mouse podocytes were exposed to AS-IV. Western blotting, immunofluorescence, and histochemistry were used to analyze markers of autophagy, mitochondrial dysfunction, podocyte apoptosis, and glomerulopathy in the progression of focal segmental glomerular sclerosis. We observed that AS-IV can inhibit podocyte apoptosis, increased reactive oxygen species (ROS) generation, mitochondrial fragmentation, and dysfunction by inducing the Mfn2/Pink1/Parkin mitophagy pathway both in vivo and in vitro. Overexpression of Mfn2 reduced puromycin aminonucleoside (PAN)-induced podocyte injury, while downregulation of Mfn2 expression limited the renal protective effect of AS-IV by regulating mitophagy. AS-IV ameliorates renal function and renal pathological changes in ADR mice and inhibits PAN-induced podocyte injury by directly enhancing Mfn2/Pink1/Parkin-associated autophagy.

Nutritional and non-nutritional strategies in bodybuilding: Impact on kidney function

Bodybuilders routinely engage in many dietary and other practices purported to be harmful to kidney health. Thus, a structured narrative review of the literature was performed. The search strategy and parameters identifying areas of importance closely followed the PRISMA statement guidelines. This resulted in 13 relevant full-text articles consisting of 8 case reports and 5 case series, published since 2000. Kidney disease was described in 75 bodybuilders, with diagnoses ranging from acute kidney injury (AKI), acute tubular necrosis , focal segmental glomerular sclerosis (FSGS), nephrocalcinosis, acute interstitial nephritis , nephrosclerosis, chronic interstitial nephritis, an assortment of other glomerulonephritides. The development of AKI, FSGS and nephrocalcinosis may be particular risks. There is little evidence that high-protein diets and moderate creatine supplementation pose risks to individuals with normal kidney function though long-term high protein intake in those with underlying impairment of kidney function is inadvisable. The links between anabolic androgenic steroid use and FSGS are stronger, and there are undoubted dangers of nephrocalcinosis in those taking high doses of vitamins A, D and E. Dehydrating practices, including diuretic misuse, and NSAID use also carry potential risks. It is difficult to predict the effects of multiple practices carried out in concert. Investigations into subclinical kidney damage associated with these practices have rarely been undertaken. Future research is warranted to identify the clinical and subclinical harm associated with individual practices and combinations to enable appropriate and timely advice.

#1464 Alterations of podocytes in focal segmental glomerulosclerosis: a pilot study

Abstract Background and Aims The molecular features of idiopathic podocytopathies remain unexplored, preventing the development of effective therapies to control the mechanisms of disease initiation and progression. This includes idiopathic focal segmental glomerulosclerosis (FSGS), one of the most common forms of immune glomerulopathies (IG) and the cause of renal failure and replacement therapy. In FSGS, podocytes undergo pronounced cytoskeletal alterations. Along with a decrease in Wilms tumor protein (WT1) and α-SMA expression, there is evidence for increased expression of intermediate filament proteins (vimentin, desmin, nestin) and Wnt/β-catenin signaling upregulation in IG. Decrease in WT1 is associated with upregulation in Wnt/β-catenin and p53 to promote podocyte dysfunction and albuminuria. Upregulation desmin increases the mechanical stability of cells, allowing podocytes to undergo morphological changes on the tensile glomerular capillary wall. This pilot study was aimed to evaluate the significance of WT1, β-catenin, and desmin glomerular expression in early primary FSGS. Method We reviewed the histopathological and clinical data of patients with biopsy proven FSGS (N = 14, experimental group), IgA nephropathy (N = 12, positive control), without AKI, infectious diseases, heart failure, respiratory insufficiency and cancer pathology. Renal surgery specimens from patients without IG (N = 12) were studied as negative control. Glomerulosclerosis was assessed as percentage of all glomeruli. Mesangial lesions were measured semi-quantitatively in scores (0-3). Glomerular WT1, β-catenin, and desmin expression was assessed by IHC-P with quantitative morphometry of IHC-staining area (open software QuPath, Orbit Image Analysis). Molecule's co-expression was analyzed by IF-p and confocal microscopy (Zeiss LSM 710; study conducted in the Center for Collective Use “Confocal microscopy” by Pavlov Institute of Physiology Russian Academy of Sciences). Results We examined young and middle-aged patients with CKD stages 1-3 and moderate morphological changes in the glomeruli. Gender, age, eGFR and the percentage of glomeruli with segmental sclerosis were not significantly different between IG groups (all p for interaction &amp;gt;0.05). Patients with FSGS have lower levels of serum albumin (p &amp;lt; 0.001) and higher levels of proteinuria (p &amp;lt; 0.001) as compared to IgAN. Glomeruli from IgAN patients showed more mesangial cell proliferation (p = 0.001), expansion of the mesangial matrix (p = 0.05) and global glomerular sclerosis (p = 0.003) as compared to FSGS. An immunomorphological study showed lower WT1 expression in both IG groups compared to the negative control. In the IgAN, lower WT1 expression was associated with higher BC area (Fig. 1A, D). BC expression did not differ between FSGS and negative control (Fig. 1B,D). In the combined IG group, BC directly correlated with global (r = 0.63, p = 0.001) and segmental (r = 0.63, p = 0.001) glomerular sclerosis. In FSGS, a trend towards to increase in the area of desmin IHC-staining was detected, however, no significant differences between groups were found (Fig. 1C,D). BC and desmin were co-localized with the podocyte marker WT1 (Fig. 2). BC and desmin were also expressed in WT1-negative glomerular cells (Fig. 2). Differential molecular expression patterns in glomeruli have been identified. In IgAN, co-expressing WT1 and BC (orange) was dominate in glomerular cells (Fig. 2A); the proportion of IHC expression of WT1 and BC in glomerular cells was directly correlated (r = 0.63, p = 0.031). In FSGS, WT1+ cells predominantly co-expressed desmin (magenta) but not BC; some glomerular cells were only desmin-positive (Fig. 2B). BC was expressed to a lesser extent compared to IgAN, and in some cells it was co-expressed with desmin (Fig. 2B). Conclusion In FSGS, an increase in desmin expression could be an early feature of pathogenesis before significant decrease in the number of WT1+ podocytes and changes in β-catenin expression. Activation of desmin likely characterizes damage and decrease in the number of functioning podocytes.

#735 The clinicopathologic prognostic factors to estimate ESRD in patients with FSGS from national wide cohort of renal biopsy

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is one of the leading causes of glomerulonephritis in Korea. FSGS can be caused by heterogenous aetiologies with subdivided by primary, secondary, and genetical forms. The proposed clinicopathologic classification is dependent on amount of proteinuria, laboratory findings of possible secondary causes, and genetic profiles, however, that may not provide definite subtypes of FSGS. Therefore, it is important to search for prognostic markers of any form of FSGS. Method We enrolled a total of 20,404 adult patients who underwent native renal biopsy from 1979 to 2018 in 18 hospitals in Korea. Clinical, demographic, and laboratory data were collected in conjunction with pathologic findings. Among diagnosis of FSGS by pathologists of each hospital, we selected patients with definite segmental sclerosis by light microscopic examination including ≥10 glomeruli and without electron dense deposits by electron microscopic examination. We excluded patients with other forms of pathologic diagnosis except FSGS, with diabetes mellitus, or with follow-up period &amp;lt; 6 months after renal biopsy. We evaluated prognostic factors to estimate the risk of ESRD which event was found from ESRD registry of the Korean Society of Nephrology or the data from each hospital. Results Among 511 selected FSGS patients, 314 (61.4%) men were included. Mean age was 45.0 ± 17.9 years at biopsy. The laboratory finding of serum creatinine, estimated GFR, and urine protein to creatinine ratio (UPCR) was 1.38 ± 0.85 mg/dl, 71.8 ± 36.6 ml/min/1.73 m2, and 4.32 ±4.84 g/g creatinine, respectively (there were no missing data). GFR &amp;lt;60 ml/min/1.73 m2 was found in 41.5 % of patients and UPCR ≥ 3.0 g/g creatinine in 41.1 % of patients. During 117.5 ± 100.1 months of follow-up period, there were 97 (19.0%) patients with incident ESRD. Clinical prognostic factors to incident ESRD were estimated GFR, diastolic blood pressure, and year of renal biopsy. Pathologic prognostic factors were glomerular size, amount of global sclerosis and segmental sclerosis, severity of increase in glomerular matrix, interstitial fibrosis, interstitial inflammation, and tubular atrophy, and presence of artherosclerosis of intrarenal vessels. Adjusted with clinicopathologic factors related to incident ESRD, Cox's proportional hazard models revealed only pathologic findings of amount of glomerular global sclerosis and segmental sclerosis and presence of tubular atrophy were the independent prognostic factors (Model with 3.5 % of missing cases and -2 log likelihood ratio is 956.9, p &amp;lt; 0.001). GFR and UPCR showed significant relationship with incidence of ESRD, however, the significance was gone in the model adjusted with pathologic findings. AUC by ROC to estimate the event of ESRD by percentage of global sclerosis (GS) was 0.601 (range; 0.538-0.663, p = 0.002) and, by percentage of segmental sclerosis (SS), 0.679 (range; 0.616-0.743, p &amp;lt; 0.001). We grouped patients with three pathology categorical variables of a criterion of GS 30.9%, SS 10.5 %, and moderate degree in severity of tubular atrophy (TA), resulted in 8 groups, and summarized into 4 groups according to the relative risk to develop ESRD (Fig. 1). UPCR was a significant risk factor to estimate ESRD only in Group 4 with the criterion of 2 g/g creatinine by the Kaplan-Meier test (p = 0.034). GFR was not a prognostic factor in any pathology subgroup. Conclusion Important prognostic factors to estimate incident ESRD were pathologic findings of global sclerosis, segmental sclerosis, and tubular atrophy in FSGS patients. Significance of UPCR and GFR as prognostic factors was varied according to pathologic findings. We need to reconsider the criterion of UPCR to initiate immunosuppressive treatment and to break down the effect of immunosuppressive treatments for FSGS according to pathologic findings at renal biopsy.

#887 Complement biomarkers in IgA nephropathy and IgA vasculitis with renal involvement: can urine rather than blood be the answer?

Abstract Background and Aims IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. Dysregulation of the complement system is considered a part of the pathogenesis and can occur both in the circulation and locally in the kidney. Despite this, most studies have focused on complement biomarkers in the blood, rather than in urine. Our aim was to evaluate a wide range of complement-related proteins in blood and urine at diagnosis and their association with disease activity in biopsy findings, proteinuria, and outcome. We added PTX-3, a protein expressed in activated endothelial cells, which can be both produced by and activate mesangial cells in IgAN and has a function in all three complement pathways. Adult-onset IgA vasculitis with renal involvement (IgAVN) shares many similarities with IgAN and cannot currently be distinguished by kidney biopsy or any established biomarker. We therefore also aimed to compare the same biomarkers between these two disorders. Method In a Swedish cohort of 96 patients with IgAN (n = 65) and IgAVN (n = 31), who had been followed prospectively for a median of 10.8 years, we performed the following analysis in plasma and urine in samples stored at the time of kidney biopsy. Analyses in plasma (p-) included C3bc, C4c, C5b-9, MASP2, MASP3, MAP1, FCN 1-3, MBL, CL11 and PTX-3 and in urine (u-) C3bc, C4c, C5b-9, MASP3, FCN2, FCN3, MBL and PTX-3. An in-house developed sandwich ELISA was used for all analyses. Kidney biopsies were classified according to the Oxford MEST-C score, describing (simplified for this small cohort) the presence vs absence (1 vs 0) of mesangial proliferation (M), endocapillary proliferation (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T) and crescents (C). Severe outcome was defined by a combination of an eGFR slope &amp;gt; 2.5 ml/min/1.73 m2 per year or end stage kidney disease. For statistical analysis, Mann-Whitney U test was performed for comparison between independent groups, Chi squared test and Fisher's test for categorical variables and Spearman's ranks test for correlation analysis. Median values are presented without IQR for this abstract. Results Urine samples were available in 59 patients (IgAN n = 39, IgAVN n = 20). Patients with detectable u-MBL (28.9%) and u-C5b-9 (27.1%) had higher levels of proteinuria than those with undetectable levels (1.5 g/d vs 0.71g/d; p = 0.009 and 2.3 g/d vs 0.7 g/d respectively; p &amp;lt; 0.001). Lower eGFR (71 ml/min/1.73 m2 vs 88 ml/min/1.73 m2; p = 0.034) were observed if u-C5b-9 was measurable. Detectable levels of u-PTX-3 and u-MBL were more often found in the presence of M1 vs M0 (53% vs 20%; p = 0.022 and 47% vs 12.5%; p = 0.011), E1 vs E0 (55% vs 14%; p = 0.001 and 40% vs 11%; p = 0.020) and C1 vs C0 (56% vs 11%; p = 0.003 and 44% vs 11%; p = 0.012). No differences in proteinuria or eGFR were seen in patients with or without detectable u-PTX-3. The degree of proteinuria was positively correlated to the levels of u-C3bc (r = 0.33; p = 0.011) and u-C4c (r = 0.39; p &amp;lt; 0.001). U-C4c levels were higher in patients with M1 vs M0 (54.4 Au/mL vs 23.8 Au/mL; p = 0.037) and T1 vs T0 (53.2 Au/mL vs 23.8 Au/mL; p = 0.034). Concerning the analyses in plasma (n = 95), lower p-MASP3 and p-CL11 levels were correlated with lower eGFR (r = 0.29; p = 0.004 and r = 0.31, p = 0.002). Moreover, lower p-MASP3 levels were detected in patients with E1 vs E0 (2918 ng/mL vs 3404 ng/mL; p = 0.002) and C1 vs C0 (3053 ng/mL vs 3427 ng/mL; p = 0.015). Both p-C5b-9 (13.3 Au/mL vs 8.2 Au/mL; p = 0.001) and p-FCN 1 (395 ng/mL vs 289 ng/mL; p = 0.001) were higher in patients with C1 vs C0. No single complement-related protein was associated with severe outcome, and no statistically significant differences in plasma or urine levels between patients with IgAN and IgAVN were observed. Conclusion Increased urinary levels of MBL and PTX-3 could be potential biomarkers of disease activity in both IgAN and IgAVN, whereas excretion of C5b-9 might be more unspecific and associated with chronic damage. However, these results need to be confirmed in larger and more ethnically diverse cohorts. The impact of treatment on these potential biomarkers for disease activity need to be evaluated in longitudinal studies.

#2168 Lupus nephritis histopathological classification system: a questionnaire-based survey of the Renal Pathology Society (RPS)

Abstract Background and Aims Kidney biopsy is the gold standard for lupus nephritis diagnosis, defining histologic class, disease activity and chronicity in detail and providing guidance for treatment. The updated 2018 ISN/RPS histopathological classification in lupus nephritis is widely used for prognosis and treatment decisions. Given the evolving phenotypes of lupus nephritis and the success of new targeted agents in clinical trials, there is ongoing discussion about the need for updating existing classification systems. A survey to assess the current use of the lupus nephritis histopathological classification systems in everyday practice was conducted on behalf of the RPS. Method An online survey was sent between September 27th and October 24th, 2023 to active members of the RPS. The survey used an internet platform and contained both multiple-choice and open-ended questions; results were analyzed anonymously. Results 185 of 562 RPS members replied to the questionnaire. 179 (97%) were pathologists and the level of expertise in lupus nephritis was good: 120 (65%) participants indicated they encounter more than 20 biopsies with lupus nephritis per year, while only 13% encounter fewer than 10. Almost 90% of responders discuss kidney biopsy results in a multidisciplinary meeting involving both clinicians and pathologists, on a weekly or monthly basis. The 2018 ISN/RPS lupus nephritis classification is used in most cases (92%), while 7% of participants prefer the earlier 2004 version. The average grade on the utility of the 2018 ISN/RPS classification was 8 (IQR 7-9) on a scale from 0 (not useful) to 10 (extremely useful). Almost 90% of the pathologist responders indicated they include the NIH activity/chronicity indices in biopsy reports. Reasons for not adding the activity/chronicity indices were given as responses to open-ended questions: (1) clinicians usually do not ask for activity/chronicity indices—(2) the extra workload outweighs the perceived clinical benefit—(3) a quantitative description of the degree of activity/chronicity is less time-consuming and more understandable than the indices—(4) reproducibility is not guaranteed. The average grade on the utility of the activity/chronicity indices was 7 (IQR 7-9) on a scale from 0 (not useful) to 10 (extremely useful). Pathologists rated treating clinicians' understanding of kidney biopsy reports and lupus classification at light microscopy with an average score of 8 (IQR 7-9) on a scale from 0 (no understanding) to 10 (complete understanding). Suggested improvements of the 2018 ISN/RPS lupus nephritis classification were further standardization and simplicity. Clearer definitions were requested for: class III vs class IV; segmental sclerosis vs fibrotic crescents; the role of globally sclerosed glomeruli; lupus-like entities; and lupus podocytopathy. Furthermore, there was a request on guidelines for new parameters: e.g., focus on extraglomerular involvement, laboratory and clinical features and biomarkers; CD68+ staining to detect endocapillary hypercellularity; and EXT1/2 immunostaining. Conclusion Our survey shows the 2018 ISN/RPS lupus nephritis classification is widely used in everyday practice by pathologists, and well known by clinicians. The results obtained by the RPS survey serve as a starting point for the new Working Group of lupus nephritis classification. We will consider the ideas and suggestions of the international community to evaluate biopsies from extensively phenotyped cohorts, to modify the classification and to facilitate improved targeted treatment decisions—a current unmet need.

#1442 Retrospective evaluation of etiology, clinical and laboratory findings in patients diagnosed with secondary and genetic FSGS

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is a glomerulonephritis characterized by segmental sclerosis in at least one of the glomeruli and may develop due to primary, secondary, genetic etiology. We compared clinical, histopathological, and laboratory findings, treatment options, and response to treatment in patients with secondary and genetic FSGS. Method This study analyzed 172 patients with secondary and genetic FSGS at our Glomerular Diseases Clinic (1987-2022). Criteria included at least 16 weeks of follow-up, absence of other primary glomerular diseases, and age over 18. Retrospective data were collected on demographics, diagnosis, renal biopsies, genetic tests, imaging, treatments, treatment responses, end-stage renal disease (ESRD) development, and transplantation. The focus was on predicting genetic FSGS and ESRD. Results 103 of our patients were female (59.8%), and the mean age at diagnosis was 38.46 ± 13.75 years. Of these patients, 29 were diagnosed with genetic FSGS and 141 with non-genetic secondary FSGS. Forty-one patients with non-genetic secondary FSGS were obese, and 21 had a single kidney. The patients had a median follow-up of 78 (38-134) months. 28 patients developed ESRD during follow-up, 16 of whom underwent renal transplantation. Familial renal disease (p &amp;lt; 0.001), familial ESRD (p &amp;lt; 0.001), and hematuria at diagnosis (p = 0.005) were more common in patients with genetic FSGS. Comparison of genetic FSGS and non-genetic secondary FSGS patients shown in Figure 1. The number of glomeruli with global sclerosis (p = 0.006) and C3 accumulation (p = 0.048) on renal biopsy was more frequent in patients with ESRD. Comparison of ESRD and non-ESRD patients are shown in Figure 2. Conclusion Differentiating genetic and non-genetic secondary FSGS is vital in clinical practice. For those with a family history of renal disease, hematuria, or unresponsive to immunosuppressive therapy, consider genetic FSGS and request genetic testing. Patients with secondary FSGS, diagnosed with high creatinine, a substantial presence of sclerosing glomeruli on biopsy, and C3 accumulation, should be closely monitored for ESRD.

Clinicopathological characteristics of pediatric ANCA-associated glomerulonephritis.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and glomerulonephritis is uncommon in children. We sought to characterize the histological and clinical features of the disease and report on risk factors for adverse outcomes in a pediatric cohort. Retrospective single-center cohort of all pediatric (< 20years) patients diagnosed with ANCA-associated glomerulonephritis (AAGN) by kidney biopsy between 2002 and 2022 at Johns Hopkins University. Histological and clinical features were extracted from the medical record. Clinical, laboratory, and histological findings were analyzed to determine the association with kidney failure (KF) and/or death. A total of 17 patients were identified (GPA n = 7, MPA = 10) with a median age of 15years (IQR 12-17) at presentation, a slight female predominance (59%), with seven patients reaching the composite outcome of death (n = 1) or kidney failure (n = 6). There was no difference in presenting clinical symptoms or extra-renal manifestations between the two groups. Univariable Cox regression identified several factors associated with an increased hazard of endpoint including the degree of global or segmental sclerosis, interstitial fibrosis and tubular atrophy (IFTA), C3 and C1q staining, presence of subendothelial deposits, and proteinuria. Multivariable regression was not performed due to the small sample size. We saw a trend towards increased utilization of plasma exchange and a decrease in cyclophosphamide utilization in the more recent era. There was no association between treatment modality and outcome. Pediatric AAGN is a rare disease associated with significant morbidity. We identified glomerulosclerosis and IFTA on histology, and proteinuria on initial presentation as risk factors for KF/death.

#2862 Genetics and electron microscopy: complementary tools for management of focal segmental glomerulosclerosis?

Abstract Background and Aims Focal segmental glomerular sclerosis (FSGS) defines a histologic lesion that represents a pattern of injury associated to different pathologic conditions affecting both children and adults. It is classified into primary forms, presumably immune-mediated, secondary forms, determined by a maladaptive response to different conditions, genetic and undetermined forms. According to Mayo Clinic classification, primary and secondary forms can de differentiated using electron microscopy (EM), with a podocytes foot process effacement (FPE) ≥80% identifying primary forms. Better understanding the role of Genetics in FSGS and response to treatment in different forms is of vital importance in this rare and multifaceted condition. We analyzed a discrete cohort of patients with FSGS examined both with EM and genetic testing (GT). Main aims of our study were: 1) assessment of GT in primary and secondary forms; 2) analysis of response to therapy according to histologic and genetic classification. Method This is a retrospective observational study on patients that received a histological diagnosis of FSGS, including EM, and underwent NGS genetic testing from January 2020 to June 2023. Primary and secondary forms of FSGS were distinguished by degree of pedicle fusion at EM, according to Mayo Clinic classification. Clinical, laboratory, genetic data and used therapies were recorded. Complete response (CR) to therapy was defined as a reduction of proteinuria to 0.3 g/day, with normalization of albuminemia. Partial response (PR) was defined as halving proteinuria into a sub-nephrotic range and increasing albuminemia up to 3.5 g/dL. Absent response was defined as a persisting nephrotic range proteinuria. Results In the study period, 33 patients receiving a histologic diagnosis of FSGS with EM examination underwent NGS testing. Of these, 25 had available genetic results and were included. Ten patients (40%) were females, 15 (60%) were males; mean age was 40.8 years (SD ±14.5); 20 (80%) were Caucasian, 4 (16%) Black, 1 (4%) Asian. Based on EM, 11 (44%) were classified as primary forms, 14 (56%) as secondary forms. Twelve (48%) patients presented with nephrotic syndrome. Of these, 10 had a primary form. Seven (28%) had nephrotic-range proteinuria without hypoalbuminemia, 6 (24%) had subnephrotic range proteinuria. Six (54.5%) of the primary forms and 8 (57.1%) of the secondary forms had a positive genetic testing (p = 0.78). Among secondary forms, through GT, one diagnosis of Fabry disease and one of Tuberous Sclerosis were made in patients without clear systemic symptoms. Fabry disease was confirmed by presence of zebra bodies at EM. All primary forms received immunosuppressive therapies, all being rituximab-based regimens; all secondary forms received support therapy. Nine (81.1%) primary forms and 9 (64.3%) secondary forms had at least a PR to treatment (4 CR in primary group and 1 CR in secondary group) (p = 0.33). Among primary forms, 5 of 6 patients (83%) with a positive GT had at least a PR with a strong immunosuppressive therapy. In secondary forms group 4 of 8 patients (50%) had at least PR with offered support therapy. Fabry and Tuberous Sclerosis were offered specific treatments with benefit. Conclusion Percentage of positive GT did not differ in primary and secondary forms of FSGS as defined by Mayo Clinic classification. Thus a positive GT should not be considered a unique feature of secondary forms. GT was critical for an unexpected diagnosis of systemic hereditary diseases, thus enabling adequate target therapies. We believe GT should be offered to all patients with FSGS. In primary FSGS, defined according to EM, more than 80% of patients had at least a PR following immunosuppressive therapy, even in patients with positive GT. In conclusion, as clinical presentation and light microscopy are not sufficient for an accurate diagnosis, combining EM and GT is of utmost importance in proper classification and management of FSGS.