Recurrent Nephrotic Plasma Activates Pro-fibrotic Signalling Pathways Downstream of Protease-activated Receptor 1

Recurrence of steroid-resistant nephrotic syndrome (SRNS) is thought to be due to an unknown “circulating factor”, the identity of which has so far remained elusive. Our previous work suggests a signaling role for protease-activated receptor-1 (PAR-1), leading to impaired podocyte function. Here, we show that relapse nephrotic plasma (NP), but not paired remission plasma, induced a pro-fibrotic response. This change was inhibited by PAR-1 inhibitors, but not by TGF-β1 inhibition. Four PAR-1 inhibitors demonstrated distinct antagonistic properties. The phosphorylation of VASP and JNK in a 3D spheroid model (GlomSpheres) and kidney organoids corroborated the finding from a 2D ciPods model. Functionally, relapse NP induced podocyte motility, and podocyte loss from spheroids both of which were also selectively rescued by PAR-1 inhibitors. Also, it induced the loss of podocyte-specific markers in kidney organoids. We propose that the circulating factor acts as a pro-fibrotic effector by activating PAR-1, leading to increased podocyte injury.

Therapeutic Response and Long-Term Renal Outcomes in Childhood Idiopathic Steroid-Resistant Nephrotic Syndrome: A Single-Center Study

<b><i>Purpose:</i></b> We aimed to evaluate therapeutic response and long-term renal outcomes of childhood idiopathic steroid-resistant nephrotic syndrome (iSRNS). <b><i>Methods:</i></b> We retrospectively reviewed treatment regimens, especially calcineurin inhibitor (CNI), pathologic diagnoses, and long-term renal outcomes of iSRNS patients for 30 years. <b><i>Results:</i></b> Of 516 patients with idiopathic NS, 52 (10.1%) had iSRNS. Renal biopsies from 48 patients showed minimal change disease (MCD) in 23 (47.9%), focal segmental glomerulosclerosis in 24 (50.0%), and mesangioproliferative glomerulonephritis in 1 (2.1%). The median follow-up period was 66.5 (range, 4–275) months, and 90.4% of them were treated with a CNI. CNI induced remission in 70.2% within 50.4 ± 43.5 days. Of the patients with MCD and focal segmental glomerular sclerosis (FSGS), 86.4% (19/22) and 45.0% (9/20) (<i>p =</i> 0.005) responded to CNI, respectively. Mean time until remission after using CNI was longer with FSGS (90.4 ± 54.0 days) than with MCD (29.6 ± 26.3 days) (<i>p =</i> 0.010). CNI-responsive patients with FSGS or MCD showed preserved renal function, and CNI nonresponsive MCD patients also showed preserved renal function during follow-up. However, end-stage renal disease (ESRD) progressed in 8 out of 11 patients with FSGS nonresponsive to the CNI for an average of 44.9 ± 18.4 months after diagnosis. <b><i>Conclusion:</i></b> Different response rates and times for remission were achieved with the CNI according to the pathology of iSRNS. All MCD patients regardless of CNI response and all CNI-responsive patients with FSGS showed excellent renal outcomes, while almost all FSGS patients nonresponsive to CNI eventually progressed to ESRD.

Guidelines for Genetic Testing and Management of Alport Syndrome

Genetic testing for pathogenic COL4A3–5 variants is usually undertaken to investigate the cause of persistent hematuria, especially with a family history of hematuria or kidney function impairment. Alport syndrome experts now advocate genetic testing for persistent hematuria, even when a heterozygous pathogenic COL4A3 or COL4A4 is suspected, and cascade testing of their first-degree family members because of their risk of impaired kidney function. The experts recommend too that COL4A3 or COL4A4 heterozygotes do not act as kidney donors. Testing for variants in the COL4A3–COL4A5 genes should also be performed for persistent proteinuria and steroid-resistant nephrotic syndrome due to suspected inherited FSGS and for familial IgA glomerulonephritis and kidney failure of unknown cause.

CLINICAL CASE: STEROID-RESISTANT NEPHROTIC SYNDROME

Описан клинический случай пациент с нефротическим синдромом, стероид резистентный вариант, с артериальной гипертензией, осложненный полисерозитом (гидроторакс, асцит, плеврит). Пациент поступил в клинику в состоянии средней степени тяжести, с массивными отеками, полисерозитом, артериальной гипертензией и выраженным нефротическим синдромом. Диагноз: Гломерулярная болезнь. Нефротический синдром, стероид резистентный вариант. Функция почек снижена (СКФ- 84мл/мин по Шварцу). Двухсторонний экссудативный плеврит. Гидроторакс. Полисерозит (в рамках нефротического синдрома) был установлен на основании выраженного нефротического синдрома. Пациенту была проведена патогенетическая терапия. Отмечено улучшение состояния больного, в виде снижения отеков, нормализаций артериального давления, что в свою очередь поспособствовало сохранению и улучшению качества жизни пациента. A clinical case of a patient with nephrotic syndrome, steroidresistant variant, with arterial hypertension complicated by polyserositis (hydrothorax, ascites, pleurisy) is described. The patient was admitted to the clinic in a state of moderate severity, with massive edema, polyserositis, arterial hypertension, and severe nephrotic syndrome. Diagnosis: Glomerular disease. Nephrotic syndrome, steroidresistant variant. The kidney function is reduced (GFR - 84 ml/min according to Schwartz). Bilateral exudative pleurisy. Hydrothorax. Polyserositis (within the framework of nephrotic syndrome) was established based on the severe nephrotic syndrome. The patient underwent pathogenetic therapy. An improvement in the patient's condition was noted, in the form of a decrease in edema, normalization of blood pressure, which in turn contributed to the preservation and improvement of the patient's quality of life.

A novel biomimetic nanomedicine system with anti-inflammatory and anti-osteoporosis effects improves the therapy efficacy of steroid-resistant nephrotic syndrome

Clinically, steroid-resistant nephrotic syndrome (SRNS) is always prolonged and difficult to treat and easily develops into end-stage renal disease, resulting in a low survival rate. Strategies to reverse steroid resistance and reduce the long-term use of high doses of steroid medicines are urgently needed. In this study, a novel nanoparticle drug system (Pm-GCH) with a core–shell structure was designed. Metal–organic frameworks, synthesized by glycyrrhizic acid (G) and calcium ions (Ca2+) loaded with hydrocortisone (H) were the core of the nanoparticles. Platelet membrane vesicles were the shells. The natural platelet membrane endows Pm-GCH with good biocompatibility and the ability to promote immune escape. In addition, under the chemotaxis of inflammatory factors, platelet membranes assist Pm-GCH in nonspecific targeting of the inflammatory sites of the kidney. Under an inflammatory acid environment, GCH slowly degrades and releases glycyrrhizic acid and hydrocortisone. Glycyrrhizic acid inhibits the inactivation of hydrocortisone, jointly inhibits the activity of phospholipase A2 (PLA2) and the classic activation pathway of complement C2, blocks the production of inflammatory factors, plays an anti-inflammatory role, and enhances the efficacy of hydrocortisone in the treatment of SRNS. Moreover, glycyrrhizic acid alleviates osteoporosis induced by long-term use of glucocorticoids. These results indicate that Pm-GCH is a promising treatment strategy for SRNS. Graphical Abstract

Intravenous cyclophosphamide induces remission in children with difficult to treat steroid resistant nephrotic syndrome from minimal change disease

Background Steroid resistant nephrotic syndrome (SRNS), while uncommon in children, is associated with significant morbidity. Calcineurin inhibitors (CNIs) remain the first line recommended therapy for children with non-genetic forms of SRNS, but some children fail to respond to them. Intravenous (IV) cyclophosphamide (CTX) has been shown to be effective in Asian-Indian children with difficult to treat SRNS (SRNS-DTT). Our study evaluated the outcome of IV CTX treatment in North American children with SRNS-DTT. Methods Retrospective review of the medical records of children with SRNS-DTT treated with IV CTX from January 2000 to July 2019 at our center. Data abstracted included demographics, histopathology on renal biopsy, prior and concomitant use of other immunosuppressive agents and serial clinical/laboratory data. Primary outcome measure was attainment of complete remission (CR). Results Eight children with SRNS-DTT received monthly doses (median 6; range 4–6) of IV CTX. Four (50%) went into CR, 1 achieved partial remission and 3 did not respond. Three of the 4 responders had minimal change disease (MCD). Excluding the 1 child who responded after the 4th infusion, the median time to CR was 6.5 (range 0.5–8) months after completion of IV CTX infusions. Three remain in CR at a median of 8.5 years (range: 3.7–10.5 years) after completion of CTX; one child relapsed and became steroid-dependent. No infections or life-threatening complications related to IV CTX were observed. Conclusions IV CXT can induce long term remission in North-American children with MCD who have SRNS-DTT.

p.R138Q and p.R229Q Screening In NPHS2 Gene in a Moroccan Cohort with Steroid Resistant Nephrotic Syndrome

Mutations in the NPHS2 gene encoding podocin are implicated in an autosomal-recessive form of nonsyndromic steroid-resistant nephrotic syndrome in both pediatric and adult patients. The p.R138Q (c.413G>A) mutation in exon 3 was the most prevalent mutation in European series. The p.R229Q (c.686G>A) variant in exon 5 is the first human variant discovered with a mutation-dependent pathogenicity. We aimed in this study to screen for the p.R138Q mutation and the p.R138Q variant in a Moroccan cohort with Steroid Resistant Nephrotic Syndrome.

Steroid-resistant nephrotic syndrome associated MYO1E mutations have differential effects on myosin 1e localization, dynamics, and activity

Myo1e is a non-muscle motor protein enriched in the podocyte foot processes. Mutations in MYO1E are associated with steroid-resistant nephrotic syndrome (SRNS). Here, we set out to differentiate between the pathogenic and neutral MYO1E variants identified in SRNS patients by exome sequencing. Based on protein sequence conservation and structural predictions, two mutations in the motor domain, T119I and D388H, were selected for this study. EGFP-tagged Myo1e constructs were delivered into the Myo1e-KO podocytes via adenoviral infection to analyze Myo1e protein stability, Myo1e localization, and clathrin-dependent endocytosis, which is known to involve Myo1e activity. Furthermore, truncated Myo1e constructs were expressed using the baculoviral expression system and used to measure Myo1e ATPase and motor activity in vitro. Both mutants were expressed as full-length proteins in the Myo1e-KO podocytes. However, unlike wild-type (WT) Myo1e, the T119I variant was not enriched at the cell junctions or clathrin-coated vesicles (CCVs) in podocytes. In contrast, the D388H variant localization was similar to the WT. Surprisingly, the dissociation of the D388H variant from cell-cell junctions and CCVs was decreased, suggesting that this mutation also affects Myo1e activity. The ATPase activity and the ability to translocate actin filaments were drastically reduced for the D388H mutant, supporting the findings from cell-based experiments. The experimental pipeline developed in this study allowed us to determine that the T119I and D388H mutations appear to be pathogenic and gain additional knowledge in the Myo1e role in podocytes. This workflow can be applied to the future characterization of novel MYO1E variants associated with SRNS.