Management of adult patients with podocytopathies: an update from the ERA Immunonephrology Working Group.

The histopathological lesions, minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are entities without immune complex deposits which can cause podocyte injury, thus are frequently grouped under the umbrella of podocytopathies. Whether MCD and FSGS may represent a spectrum of the same disease remains a matter of conjecture. Both frequently require repeated high-dose glucocorticoid therapy with alternative immunosuppressive treatments reserved for relapsing or resistant cases and response rates are variable. There is an unmet need to identify patients who should receive immunosuppressive therapies as opposed to those who would benefit from supportive strategies. Therapeutic trials focusing on MCD are scarce, and the evidence used for the 2021 Kidney Disease: Improving Global Outcomes (KDIGO) guideline for the management of glomerular diseases largely stems from observational and pediatric trials. In FSGS, the differentiation between primary forms and those with underlying genetic variants or secondary forms further complicates trial design. This article provides a perspective of the Immunonephrology Working Group (IWG) of the European Renal Association (ERA) and discusses the KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases focusing on the management of MCD and primary forms of FSGS in the context of recently published evidence, with a special emphasis on the role of rituximab, cyclophosphamide, supportive treatment options and ongoing clinical trials in the field.

Anterior and posterior ischemic optic neuropathy in a child with focal segmental glomerulosclerosis on hemodialysis.

BACKGROUND: Ischemic optic neuropathy (ION) is exceedingly rare in children on dialysis, resulting from poor perfusion of the optic nerve, and presents as sudden acute painless vision loss. CASE-DIAGNOSIS/TREATMENT: We report the case of a 3-year-old male with stage 5 chronic kidney disease (CKD 5) due to focal segmental glomerulosclerosis (FSGS) status post-bilateral nephrectomy on chronic hemodialysis who had acute loss of vision several hours after a hemodialysis session. Earlier that day, he had a drop in blood pressure intra-dialysis to 89/67 mmHg, with at home blood pressures ranging 90/60 to 150/100 mmHg. The patient was treated with tight blood pressure control to maintain blood flow and prevent blood pressure lability, received high-dose corticosteroids with a corticosteroid taper, and placed on high-dose erythropoietin for neuroprotective effect. He regained partial vision beginning approximately 1 month after presentation. CONCLUSIONS: The exact cause of our patient's simultaneous bilateral anterior and posterior ION, confirmed via MRI and fundoscopic examination, is unclear; however, is likely secondary to a combination of fluctuating blood pressure, anemia, anephric status, and hemodialysis. This highlights the need for close blood pressure monitoring, management of anemia, and more diligent ophthalmologic screening in pediatric patients on chronic hemodialysis.

Nephrotic syndrome due to focal segmental glomerulosclerosis complicating scleroderma: a case report.

BACKGROUND: Systemic scleroderma (SSc) is an insidious autoimmune connective tissue disorder with multiorgan involvement. Renal involvement is one of the important causes of morbidity and mortality in scleroderma; however, nephrotic syndrome is reported rarely in association with SSc. We present a patient with SSc who developed focal segmental glomerulosclerosis (FSGS) as a complication of scleroderma. CASE PRESENTATION: A 59 year old Caucasian female patient, with a known history of diffuse systemic sclerosis from 8 years, presented to our clinic with symptoms of anasarca and weight gain. Her physical examination was unremarkable except for periorbital and extremity edema. Her biochemistry assessment revealed decreased serum albumin levels and elevated serum creatinine levels. A renal biopsy was performed, which showed histopathological patterns of FSGS type of nephrotic syndrome. After administration of high doses of steroid and rituximab in the course of her treatment for 6 months, her symptoms and proteinuria were improved without the occurrence of scleroderma renal crises. CONCLUSION: SSc is a complex multisystemic autoimmune disorder. SRC is the most prominent renal involvement in SSc, but other renal pathologies may also occur. Each patient should be precisely investigated since managing these renal conditions can differ significantly. Nephrotic syndrome is a rare complication of SSc, which could be managed with prompt diagnosis and steroid administration.

The Impact of Obesity on Kidney Disease: Observational Cohort Study Analyzing 14,492 Kidney Biopsy Cases.

BACKGROUND: The obesity epidemic is associated with the emergence of new kidney diseases including obesity-related glomerulopathy (ORG) and metabolic syndrome-associated disorders. However, the effects of obesity on prevalence and outcome of biopsy-proven kidney disease are not well known. METHODS: We analyzed 14,492 kidney biopsies in 18 hospitals from 1979 to 2018 in Korea. Obesity was defined as a body mass index value of ≥ 30 kg/m². RESULTS: The most common disease was IgA nephropathy (IgAN) in both obese and non-obese participants (33.7% vs. 38.9%). Obesity was associated with a higher risk of focal segmental glomerulosclerosis (FSGS) and hypertensive nephropathy (HT-N) (odds ratio [OR], 1.72, 95% confidence interval [CI], 1.37-2.17; OR, 1.96, 95% CI, 1.21-3.19) and a lower risk of IgAN (OR, 0.74, 95% CI, 0.62-0.88). During the median follow up of 93.1 ± 88.7 months, obesity increased the risk of end-stage kidney disease (ESKD) in patients with IgAN (relative risk [RR], 1.49, 95% CI, 1.01-2.20) and lupus nephritis (LN) (RR, 3.43, 95% CI, 1.36-8.67). Of 947 obese individuals, ORG was detected in 298 (31.5%), and 230 participants had other kidney diseases, most commonly, IgAN (40.9%) followed by diabetic nephropathy (15.2%). Participants with ORG, when combined with other renal diseases, showed higher risks for developing ESKD compared to those with ORG alone (RR, 2.48, 95% CI, 1.09-5.64). CONCLUSION: Obesity is associated with an increased risk of FSGS and HT-N, and also increase the ESKD risk in IgAN and LN patients. ORG in obese participants may have favorable renal outcomes if it occurs alone without any other renal disease.

Efficacy of Rituximab for Minimal Change Disease and Focal Segmental Glomerulosclerosis with Frequently Relapsing or Steroid-Dependent Nephrotic Syndrome in Adults: A Chinese Multicenter Retrospective Study.

INTRODUCTION: Rituximab has been proven effective and safe in pediatric patients with frequently relapsing or steroid-dependent nephrotic syndrome (FR/SDNS). We aimed to analyze the efficacy and safety of rituximab in adult FR/SDNS patients with minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). METHODS: A retrospective cohort study at three nephrology centers in China included adult FR/SDNS patients with biopsy-proven MCD or FSGS. Primary outcomes were relapse frequency and first relapse-free survival time. Adverse events were well recorded, and logistic regression analyses were used to investigate the risk factors of relapse. RESULTS: Eighty-one patients (age, 25.0 years; interquartile range, 20.0-40.5; 67% males; 82.7% MCD) received an average rituximab dose of 1,393.8 ± 618.7 mg/2 years during the 2-year follow-up period. The relapse frequency, calculated as the ratio of relapse times to follow-up years, significantly decreased after rituximab treatment (0.04 [0.00, 0.08] vs. 1.71 [1.00, 2.45], p < 0.001). The first relapse-free survival time was 16.7 ± 8.0 months. Fifty-seven patients (70.4%) achieved cessation of corticosteroids and immunosuppressants within 3 months after the first rituximab infusion. Adverse events were mostly mild, and no severe treatment-related adverse events were observed. Low serum albumin level before rituximab and high CD56+CD16+ natural killer cell count after rituximab were independent risk factors of relapse within 2 years after rituximab treatment. CONCLUSION: Rituximab was proven an effective and safe treatment option for adult FR/SDNS patients with MCD or FSGS in maintaining disease remission and minimizing corticosteroid exposure.

Ocular manifestations of the genetic causes of focal and segmental glomerulosclerosis.

Genetic forms of focal and segmental glomerulosclerosis (FSGS) often have extra-renal manifestations. This study examined FSGS-associated genes from the Genomics England Renal proteinuria panel for reported and likely ocular features. Thirty-two of the 55 genes (58%) were associated with ocular abnormalities in human disease, and a further 12 (22%) were expressed in the retina or had an eye phenotype in mouse models. The commonest genes affected in congenital nephrotic syndrome (NPHS1, NPHS2, WT1, LAMB2, PAX2 but not PLCE1) may have ocular manifestations . Many genes affected in childhood-adolescent onset FSGS (NPHS1, NPHS2, WT1, LAMB2, SMARCAL1, NUP107 but not TRPC6 or PLCE1) have ocular features. The commonest genes affected in adult-onset FSGS (COL4A3-COL4A5, GLA ) have ocular abnormalities but not the other frequently affected genes (ACTN4, CD2AP, INF2, TRPC6). Common ocular associations of genetic FSGS include cataract, myopia, strabismus, ptosis and retinal atrophy. Mitochondrial forms of FSGS (MELAS, MIDD, Kearn's Sayre disease) are associated with retinal atrophy and inherited retinal degeneration. Some genetic kidney diseases (CAKUT, ciliopathies, tubulopathies) that result in secondary forms of FSGS also have ocular features. Ocular manifestations suggest a genetic basis for FSGS, often help identify the affected gene, and prompt genetic testing. In general, ocular abnormalities require early evaluation by an ophthalmologist, and sometimes, monitoring or treatment to improve vision or prevent visual loss from complications. In addition, the patient should be examined for other syndromic features and first degree family members assessed.

The epidemiology of primary FSGS including cluster analysis over a 20-year period.

INTRODUCTION: Focal segmental glomerulosclerosis (FSGS) is one of the leading causes of nephrotic syndrome in adults. This epidemiological study describes a renal centre's 20-year experience of primary FSGS. METHODS: Patients were identified with a diagnosis of primary FSGS after exclusion of known secondary causes. In this retrospective observational study, data was collected for baseline demographics, immunosuppression and outcomes. A two-step cluster analysis was used to identify natural groupings within the dataset. RESULTS: The total cohort was made up of 87 patients. Those who received immunosuppression had lower median serum albumin than those who did not- 23g/L vs 40g/L (p<0.001) and higher median urine protein creatinine ratios (uPCR)- 795mg/mmol vs 318mg/mmol (p <0.001). They were more likely to achieve complete remission (62% vs 40%, p=0.041), but relapsed more 48.6% vs 22% (p=0.027). Overall 5 year mortality was 10.3% and 5 year progression to RRT was seen in 17.2%. Complete remission was observed in 49.4%. The 2-step cluster analysis separated the cohort into 3 clusters: cluster 1 (n=26) with 'nephrotic-range proteinuria'; cluster 2 (n=43) with 'non-nephrotic-range proteinuria'; and cluster 3 (n=18) with nephrotic syndrome. Immunosuppression use was comparable in clusters 1 and 3, but lower in cluster 2 (77.8% and 69.2% vs 11.6%, p<0.001). Rates of complete remission were greatest in clusters 1 and 3 vs cluster 2: 57.7% and 66.7% vs 37.2%. CONCLUSION: People who received immunosuppression had lower serum albumin and achieved remission more frequently, but were also prone to relapse. Our cluster analysis highlighted 3 FSGS phenotypes: a nephrotic cluster that clearly require immunosuppression; a cohort with preserved serum albumin and non-nephrotic range proteinuria who will benefit from supportive care; and lastly a cluster with heavy proteinuria but serum albumin > 30g/L. This group may still have immune mediated disease and thus could potentially benefit from immunosuppression. TRIAL REGISTRATION: This study protocol was reviewed and approved by the 'Research and Innovation committee of the Northern Care Alliance NHS Group', study approval number (Ref: ID 22HIP54).

Clinicopathological differences in focal segmental glomerulosclerosis depending on the accompanying pathophysiological conditions in renal allografts.

Primary focal segmental glomerulosclerosis (FSGS) is thought to be caused by circulating factors leading to podocytopathy, whereas segmental sclerotic lesions (FSGS lesions) have several causes. We studied the clinicopathological differences of FSGS-lesions in 258 cases of FSGS in renal allografts, depending on the following accompanying pathophysiology: recurrence of primary FSGS, calcineurin inhibitor (CNI)-induced arteriolopathy, antibody-mediated rejection (ABMR), and other conditions. All cases were categorized with the Columbia classification. Recurrent FSGS developed the earliest after transplantation and showed the highest percentage of the collapsing (COL) variant in which collapse of the glomerular capillaries with epithelial hypertrophy was apparent. FSGS accompanying CNI-induced arteriolopathy predominantly developed the not otherwise specified (NOS) variant, showing severe ultrastructural endothelial injury. On the contrary, approximately 7% of the cases showed the COL variant, presenting glomerular endothelial damage such as double contours of glomerular basement membrane and endothelial cell swelling as well as epithelial cell proliferation. FSGS with ABMR had the highest creatinine levels and cellular variant percentage, with marked inflammation and ultrastructural endothelial injury. Approximately two-thirds of the cases without ABMR, CNI-induced arteriopathy, or recurrent FSGS had other coexisting conditions such as glomerulonephritis, T cell-mediated rejection, and reflux nephropathy with progressive tubulointerstitial fibrosis. Most of these cases were of the NOS variant. The clinicopathologic features of post-transplant FSGS differed depending on the associated conditions, and endothelial injury was apparent especially in cases of CNI-induced arteriolopathy and ABMR. Precise observation of FSGS lesions may facilitate the diagnosis and clinical management of FSGS during renal transplantation.

Sparsentan versus Irbesartan in Focal Segmental Glomerulosclerosis.

BACKGROUND: An unmet need exists for focal segmental glomerulosclerosis (FSGS) treatment. In an 8-week, phase 2 trial, sparsentan, a dual endothelin-angiotensin receptor antagonist, reduced proteinuria in patients with FSGS. The efficacy and safety of longer-term treatment with sparsentan for FSGS are unknown. METHODS: In this phase 3 trial, we enrolled patients with FSGS (without known secondary causes) who were 8 to 75 years of age; patients were randomly assigned to receive sparsentan or irbesartan (active control) for 108 weeks. The surrogate efficacy end point assessed at the prespecified interim analysis at 36 weeks was the FSGS partial remission of proteinuria end point (defined as a urinary protein-to-creatinine ratio of ≤1.5 [with protein and creatinine both measured in grams] and a >40% reduction in the ratio from baseline). The primary efficacy end point was the estimated glomerular filtration rate (eGFR) slope at the time of the final analysis. The change in eGFR from baseline to 4 weeks after the end of treatment (week 112) was a secondary end point. Safety was also evaluated. RESULTS: A total of 371 patients underwent randomization: 184 were assigned to receive sparsentan and 187 to receive irbesartan. At 36 weeks, the percentage of patients with partial remission of proteinuria was 42.0% in the sparsentan group and 26.0% in the irbesartan group (P = 0.009), a response that was sustained through 108 weeks. At the time of the final analysis at week 108, there were no significant between-group differences in the eGFR slope; the between-group difference in total slope (day 1 to week 108) was 0.3 ml per minute per 1.73 m2 of body-surface area per year (95% confidence interval [CI], -1.7 to 2.4), and the between-group difference in the slope from week 6 to week 108 (i.e., chronic slope) was 0.9 ml per minute per 1.73 m2 per year (95% CI, -1.3 to 3.0). The mean change in eGFR from baseline to week 112 was -10.4 ml per minute per 1.73 m2 with sparsentan and -12.1 ml per minute per 1.73 m2 with irbesartan (difference, 1.8 ml per minute per 1.73 m2; 95% CI, -1.4 to 4.9). Sparsentan and irbesartan had similar safety profiles, and the frequency of adverse events was similar in the two groups. CONCLUSIONS: Among patients with FSGS, there were no significant between-group differences in eGFR slope at 108 weeks, despite a greater reduction in proteinuria with sparsentan than with irbesartan. (Funded by Travere Therapeutics; DUPLEX ClinicalTrials.gov number, NCT03493685.).

The outcomes of patients with kidney failure due to focal segmental glomerulosclerosis (FSGS) in Australia and New Zealand: A cohort study using the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA).

BACKGROUND: The outcomes of patients with focal segmental glomerulosclerosis (FSGS) on kidney replacement therapy (KRT) have not been well described. This study evaluated the outcomes of patients with kidney failure due to FSGS on KRT including dialysis and kidney transplantation. METHOD AND MATERIALS: All adult patients with kidney failure who commenced KRT in Australia and New Zealand from 15th of May 1963 to 31st of December 2018 were retrospectively extracted from the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. Outcomes of patients with FSGS were compared to those with other causes of kidney failure (non-FSGS). RESULTS: 85,052 patients commenced KRT during the study period, of whom 2991 (3.5%) were patients with FSGS. Compared to patients with non-FSGS, patients with FSGS experienced similar mortality on dialysis (adjusted hazard ratio [aHR] 0.98, 95% CI 0.90-1.06, p = 0.55) and following kidney transplantation (aHR 0.92, 95% CI 0.73-1.15, p = 0.47). The risk of first kidney allograft loss was higher in patients with FSGS (aHR 1.20, 95% CI 1.04-1.37, p = 0.01). However, when death was analysed as a competing risk, the survival in both groups was similar (sub-hazard ratio [SHR] 1.09, 95% CI 0.94-1.28, p = 0.26). Patients with FSGS had a longer waiting time for kidney transplantation (aHR 0.92, 95% CI 0.86-0.98, p = 0.02) and experienced an increased risk of disease recurrence in the allograft (aHR 1.73, 95% CI 1.35-2.21, p<0.001). Compared to patients with other forms of glomerular disease, patients with FSGS experienced similar dialysis and transplant patient survival and death-censored rate of kidney transplantation and allograft loss but higher rates of primary kidney disease recurrence. CONCLUSION: FSGS was associated with similar dialysis and transplant patient survival and death-censored first allograft loss compared to non-FSGS and other forms of glomerular disease.

Development of a Conceptual Model for the Patient Experience of Focal Segmental Glomerulosclerosis (FSGS): A Qualitative Targeted Literature Review.

INTRODUCTION: Focal segmental glomerulosclerosis (FSGS) is a leading cause of kidney disease and can progress to end stage kidney disease (ESKD). An overview of symptoms and impacts of the disease experienced will help inform the selection or development of fit-for-purpose clinical outcome assessments (COA) to be used in FSGS clinical trials. This study aimed to develop a conceptual model (CM) of the adult and pediatric patient experience of FSGS including disease signs/symptoms, treatment side-effects, and impact on functioning and wellbeing. METHODS: This study comprised a systematic review and thematic analysis of qualitative studies with adults and pediatric patients diagnosed with FSGS. Data sources were identified through an electronic database search of journal articles (Medline, Embase, PsycINFO; June 2021) and hand-searching of conference proceedings, patient advocacy group websites, and gray literature. Non-English articles were excluded. Identified data (patient/caregiver quotes, author summaries, and interpretations of patient experiences) were extracted from the articles. Extracted data were qualitatively analyzed aided by ATLAS.ti v7. Codes were applied to data and concepts (symptoms/impacts) were identified, named, and refined. A CM was developed by grouping related concepts into domains. RESULTS: In total, 12 sources were identified for analysis: 6 journal articles and 6 series of patient testimonials. Salient sign/symptom/side-effect domains included swelling/puffiness (edema), pain/aches/discomfort, fatigue, weight changes, skin problems, respiratory problems, and sleep problems. Salient impact domains included emotional/psychological wellbeing, physical functioning/activities of daily living, social functioning, and work/school. CONCLUSION: Secondary analysis of published qualitative literature permitted development of a CM describing the adult and pediatric experience of FSGS. Concept elicitation interviews are recommended to refine the CM, confirm the salient/most bothersome concepts, and confirm the extent of impact on daily life. The refined CM will provide a useful tool to inform the selection, development, and/or amendment of COAs for use in future FSGS clinical trials.

Calcineurin inhibitors or cyclophosphamide in the treatment of membranous nephropathy superimposed with FSGS lesions: a retrospective study from China.

BACKGROUND: Cyclophosphamide (CTX) and calcineurin inhibitors (CNIs) based regimens are recommended as immunosuppressive therapies for patients with idiopathic membranous nephropathy (IMN). Focal and segmental glomerular sclerosis (FSGS) lesions, which are common in membranous nephropathy (MN), are poor predictors of outcome. This study compared the differences of prognosis between two regimens in patients with IMN combined with FSGS lesions. METHODS: This retrospective study enrolled 108 patients with biopsy-proven IMN, accompanied with FSGS lesions, nephrotic syndrome and an estimated glomerular filtration rate (eGFR)≥60 mL/min/1.73 m2 who were treated with CTX or CNIs. We used propensity score matching (PSM) for balancing the confounding variables. RESULTS: During follow-up, 10 patients (10/55 [18.2%]; nine males) in the CNIs group showed a 50% decline in eGFR; eight had a not otherwise specified variant. Patients initially treated with CNIs had a significantly higher risk of progression to the primary outcome and a lower probability of complete or total remission. The relapse rate was higher in patients who initially received CNIs- than in those who received CTX-based treatment. Before PSM, age and 24-h urine protein level differed significantly between the groups. The PSM model included data from 72 patients. Worse outcomes were also noted among patients who initially received CNIs than those who received CTX-based treatments after matching. CONCLUSIONS: Patients with MN combined with FSGS lesions have a higher risk of renal functional decline and a higher rate of relapse after CNIs than after CTX therapy.

Urinary SPP1 has potential as a non-invasive diagnostic marker for focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a type of chronic glomerular nephropathy showing characteristic glomerular sclerosis, diagnosed by kidney biopsy. However, it is difficult and expensive to monitor disease progression with repeated renal biopsy in clinical practice, and thus here we explored the feasibility of urine biomarkers as non-invasive diagnostic tools. We downloaded scRNA-seq datasets of 20 urine cell samples and 3 kidney tissues and obtained two gene lists encoding extracellular proteins for bioinformatic analysis; in addition, we identified key EP-Genes by immunohistochemical staining and performed bulk RNA sequencing with 12 urine samples. We report that urine cells and kidney cells were correlated. A total of 64 EP-Genes were acquired by intersecting genes of distal tubular cluster with extracellular proteins. Function enrichment analysis showed that EP-Genes might be involved in the immune response and extracellular components. Six key EP-Genes were identified and correlated with renal function. IMC showed that key EP-Genes were located mainly in tubules. Cross verification and examination of a urine RNAseq dataset showed that SPP1 had diagnostic potential for FSGS. The presence of urine SPP1 was primarily associated with macrophage infiltration in kidney, and the pathogenesis of FSGS may be related to innate immunity. Urinary cells seemed to be strongly similar to kidney cells. In summary, SPP1 levels reflect renal function and may have potential as a biomarker for non-invasive diagnosis of FSGS.

Updated evidence of beneficial effect of LDL apheresis for refractory nephrotic syndrome due to a variety of causative diseases for nationwide and global approval.

Low-density lipoprotein apheresis (LDL-A) therapy has shown reasonable efficacy in treating nephrotic syndrome (NS) refractory to initial drug therapy and has been covered by National Health Insurance for the indication of drug-resistant focal segmental glomerulosclerosis (FSGS) since 1992 in Japan and has contributed to liberating substantial number of patients of this disease from entering into end-stage renal disease by easier practical application in actual clinical settings. Subsequently, various beneficial evidence of this treatment has accumulated on those other than FSGS, however, due to the limitation of covered disease insurance only for FSGS, patients with diseases other than FSGS are unlikely to benefit from this treatment in practice. This review summarizes the therapeutic evidence of the beneficial effect of LDL-A accumulated to date and the mechanisms of action analyzed from multifaceted perspectives. examines the applicability of expanding insurance coverage for diseases other than FSGS.

Rituximab treatment for refractory nephrotic syndrome in adults: a multicenter retrospective study.

BACKGROUND: The treatment of refractory nephrotic syndrome (RNS) is full of challenges and the role of rituximab (RTX) is not well-established, thus this study aims to demonstrate the role of RTX in RNS. METHODS: This was a multicenter retrospective study of all adult patients receiving RTX for RNS. Patients enrolled were divided into two groups according to pathological pattern: 20 patients as a group of podocytopathy (including minimal change disease [MCD] and focal and segmental glomerulosclerosis [FSGS]), and 26 patients as membranous nephropathy (MN) group. The remission rate, relapse rate, adverse effects, and predictors of remission were analyzed. RESULTS: A total of 75 patients received RTX for RNS and 48 were available for analysis after exclusion criteria. No significant difference in the remission rate at 6 or 12 months was observed between the MCD/FSGS and MN cases (p > 0.05). The median duration of the first complete remission (CR) was 1 month in the podocytopathy group and 12.5 months in the MN group. Three relapses were associated with infection as the ultimate outcome, and 6 out of 48 remained refractory representing a response rate of 87.5% in RNS. Clinical predictors of cumulative CR were estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 and mean arterial pressure (MAP) ≤103 mmHg at the beginning of therapy in patients with MN. No serious adverse effects were reported. CONCLUSIONS: RTX appears to be effective in RNS across various clinical and pathological subtypes, exhibiting a low relapse rate and minimal significant side effects in the majority of patients.

Characterization of cytoskeletal and structural effects of INF2 variants causing glomerulopathy and neuropathy.

Focal segmental glomerulosclerosis (FSGS) is a common glomerular injury leading to end-stage renal disease. Monogenic FSGS is primarily ascribed to decreased podocyte integrity. Variants between residues 184 and 245 of INF2, an actin assembly factor, produce the monogenic FSGS phenotype. Meanwhile, variants between residues 57 and 184 cause a dual-faceted disease involving peripheral neurons and podocytes (Charcot-Marie-Tooth CMT/FSGS). To understand the molecular basis for INF2 disorders, we compared structural and cytoskeletal effects of INF2 variants classified into two subgroups: One (G73D, V108D) causes the CMT/FSGS phenotype, and the other (T161N, N202S) produces monogenic FSGS. Molecular dynamics analysis revealed that all INF2 variants show distinct flexibility compared to the wild-type INF2 and could affect stability of an intramolecular interaction between their N- and C-terminal segments. Immunocytochemistry of cells expressing INF2 variants showed fewer actin stress fibers, and disorganization of cytoplasmic microtubule arrays. Notably, CMT/FSGS variants caused more prominent changes in mitochondrial distribution and fragmentation than FSGS variants and these changes correlated with the severity of cytoskeletal disruption. Our results indicate that CMT/FSGS variants are associated with more severe global cellular defects caused by disrupted cytoskeleton-organelle interactions than are FSGS variants. Further study is needed to clarify tissue-specific pathways and/or cellular functions implicated in FSGS and CMT phenotypes.

A clinicopathological and prognostic study of 18 children with C1q nephropathy and focal segmental glomerulosclerosis: an 18-year experience from a single center.

BACKGROUND: C1q nephropathy is a relatively rare glomerulonephritis characterized by dominant mesangial deposition of C1q. Even though C1q nephropathy has been described for more than three decades, the clinicopathological features and renal outcomes remain unclear. C1q nephropathy may present diverse morphological patterns, including focal segmental glomerulosclerosis and, the notion of C1q nephropathy as a separate disease entity is still debated. This study aimed to describe the clinical and prognostic relevance of C1q nephropathy in children with primary focal segmental glomerulosclerosis. METHODS: Three hundred eighty-nine children were diagnosed with primary focal segmental glomerulosclerosis in Jinling Hospital from 2003 to 2020. Among them, 18 cases fulfilled the criteria for C1q nephropathy. We then selected as a control group 18 children with primary focal segmental glomerulosclerosis without C1q nephropathy matched to those with C1q nephropathy for age, sex, and period of renal biopsy. Clinical and prognostic parameters were compared in children with and without C1q nephropathy. Renal end-point was defined as a ≥ 40% reduction in estimated glomerular filtration rate or end-stage renal disease. RESULTS: Four point sixty-three percent (18/389) of primary focal segmental glomerulosclerosis cases were diagnosed with C1q nephropathy. The male-to-female ratio of patients diagnosed with C1q nephropathy was 1:1. The median age at biopsy and age at onset was 15.63 (13.00-16.50) years and 14.50 (9.00-16.00) years, respectively. The prevalence of nephrotic syndrome, hematuria, and hypertension was 38.90% (7/18), 72.20% (13/18), and 33.30% (5/18), respectively. Four (22.2%) patients were steroid-dependent, 13 (72.2%) patients were steroid-resistant, and 1 (5.6%) patient developed secondary steroid-resistance. During a follow-up of 52.24 (25.00-72.47) months, 10 (55.6%) patients achieved remission, and 5 (27.8%) progressed to the end-point [including 2 (11.11%) patients who developed end-stage kidney disease]. There was no significant difference in the estimated end-stage renal disease-free survival rates, the estimated end-point-free survival rates, and the long-term remission rate between patients with and without C1q nephropathy (Kaplan-Meier, Log-rank, all P > 0.05). CONCLUSIONS: C1q nephropathy was rare in pediatric patients with focal segmental glomerulosclerosis. These patients usually had poor response to steroids. The long-term renal outcomes and remission of children with primary focal segmental glomerulosclerosis with C1q nephropathy were comparable to those without C1q nephropathy.

Nephrotic syndrome: pathophysiology and consequences.

In patients with kidney disease, nephrotic syndrome can lead to several complications including progressive kidney dysfunction. Proteinuria may lead to the formation of cellular or fibrous crescents with reciprocal development of rapidly progressive glomerulonephritis or focal glomerulosclerosis. Proteinuria may also cause overload and dysfunction of tubular epithelial cells, eventually resulting in tubular atrophy and interstitial fibrosis. Hypoalbuminemia is usually associated with increased risk of mortality and kidney dysfunction. Dyslipidemia may increase the risk of atherosclerotic complications, cause podocyte dysfunction and contribute to vascular thrombosis. Urinary loss of anticoagulants and overproduction of coagulation factors may facilitate a hypercoagulable state. Edema, hypogammaglobulinemia, loss of complement factors, and immunosuppressive therapy can favor infection. Treatment of these complications may reduce their impact on the severity of NS. Nephrotic syndrome is a kidney disorder that can worsen the quality of life and increase the risk of kidney disease progression.

CMV-associated collapsing focal segmental glomerulosclerosis after kidney transplant in a pediatric patient.

BACKGROUND: Cytomegalovirus (CMV) is a significant cause of morbidity among immunocompromised patients who have undergone kidney transplantation and is known to rarely induce collapsing focal segmental glomerulosclerosis (FSGS) among adults. METHODS: We present the first reported case of CMV-induced collapsing FSGS in a pediatric patient after kidney transplant. RESULTS: Our patient underwent a deceased donor kidney transplant due to end-stage renal disease secondary to lupus nephritis. Approximately 4 months after transplantation, he developed signs of worsening kidney function in the setting of CMV viremia and was found to have collapsing features of FSGS on kidney transplant biopsy. He was managed with a prompt escalation of antiviral therapy along with a reduction of immunosuppression and recovered without significant complication. At follow-up, he continued to have undetectable CMV titers, creatinine within normal limits, and no significant proteinuria. CONCLUSION: This report demonstrates CMV as a cause of collapsing FSGS and should be considered among pediatric transplant recipients who present with acute kidney injury, as should early assessment of APOL1 genetic status in both donor and recipient.