Anuria after kidney transplantation diagnosed as early recurrence of focal segmental glomerulosclerosis combined with acute calcineurin inhibitor nephrotoxicity: a case report and literature review.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) is a glomerular disease that sometimes recurs in patients after kidney transplantation (KT) and increases the risk of graft loss. Proteinuria is a common early sign of recurrent FSGS, but an abrupt decrease in urine volume is rare. Herein, we report a patient with early recurrence of FSGS with anuria following KT. CASE PRESENTATION: A 55-year-old man with end-stage kidney disease caused by primary FSGS experienced anuria on postoperative day 2 following deceased donor KT. Laboratory results revealed that serum tacrolimus trough levels were consistently elevated at the time of anuria. At first, we considered acute calcineurin inhibitor (CNI) nephrotoxicity based on graft biopsy on light microscopy, laboratory findings, and clinical courses. However, the allograft function did not recover even after discontinuation of CNI, and recurrent FSGS was diagnosed 2 weeks later on electron microscopy. A total of 13 sessions of plasmapheresis and two administrations of rituximab (375 mg/m2) were required to treat recurrent FSGS. The patient achieved a partial response, and the spot urine protein-to-creatinine ratio decreased from 15.5 g/g creatinine to 5.2 g/g creatinine. At 5 months following KT, the serum creatinine level was stable at 1.15 mg/dL. CONCLUSIONS: These findings highlight that anuria can occur in cases of early recurrence of FSGS combined with acute CNI nephrotoxicity.

Stage lighting on PAR-1: a step further in the understanding of acquired focal and segmental glomerulosclerosis.

The pathogenic mechanisms of acquired focal and segmental glomerular sclerosis are only partially known and represent a medical challenge in nephrology. The article by May et al. sheds additional light on previous data indicating the key role of the protease-activated receptor 1. The new evidence is based on in vivo studies in relevant animal models and on patient biopsies and represents a significant step forward in the understanding of this pathologic condition.

Post-operative recurrence of focal segmental glomerulosclerosis according to pre-transplant treatment after kidney transplantation.

BACKGROUND: Recurrent focal segmental glomerulosclerosis (FSGS) after kidney transplantation (KT) is a serious complication and a significant risk factor for graft failure. However, there is no clear evidence of the effectiveness of pre-transplant treatment using plasmapheresis (PP) or rituximab in preventing post-operative FSGS recurrence after KT. METHODS: This single-center retrospective study included 99 adult patients with biopsy-proven primary FSGS who underwent KT between 2007 and 2018. The patients were divided into the pre-treatment group (N = 53, 53.5%) and no pre-treatment group (N = 46, 46.5%). In the pre-transplant group, prophylactic PP was administered before KT in patients undergoing living donor transplantation and the day after KT in those undergoing deceased donor transplantation. RESULTS: The rate of immediate post-operative recurrence was significantly higher in the no pre-treatment group (16 [34.8%]) than in the pre-treatment group (5 [9.4%]; P = 0.002). There were three cases of graft failure due to recurrent FSGS, all of which were in the no pre-treatment group. After adjusting for possible confounding factors, age (per 10-year increase; OR = 0.61, CI, 0.42-0.90; P = 0.012) and pre-transplant treatment (vs. no pre-transplant treatment; OR = 0.17, CI, 0.05-0.54; P = 0.003) were identified as significant factors associated with FSGS recurrence. The rate of death-censored graft survival was significantly superior in the pretransplant treatment group (P = 0.042). CONCLUSION: Pre-transplant treatment with PP was associated with beneficial effects on preventing FSGS recurrence after KT.

A Rare Case Report of Postoperative Paraneoplastic Glomerulopathy in Kidney Transplant.

Kidney transplant recipients are more likely to develop posttransplant renal cell carcinoma than the general population. Symptoms of renal cell carcinoma are often nonspecific, such as nausea, vomiting, and weight loss, and tend to occur syndrome caused by the release of peptides and hormones by the cancer itself. However, there have been rare case reports of postoperative paraneoplastic glomerulopathy associated with renal cell carcinoma in kidney transplant recipients. Here, we report the case of a 54-year-old male who presented with subnephrotic range proteinuria with a urine protein-to-creatinine ratio of 1.0 within 1 year after a deceased donor kidney transplant without kidney function decline. The transplant team decided to perform a biopsy of the transplanted kidney, and the ultrasonography before intervention revealed a right- side native renal mass. The result of the kidney biopsy revealed focal segmental glomerulosclerosis. At the same time, computed tomography was done to find the cause of the renal mass, and we found that the right native kidney mass had features highly suspicious for renal cell carcinoma. The urologist subsequently performed a right radical nephrectomy. The pathology diagnosis of the kidney mass was renal cell carcinoma. After the cancer had been eliminated, clinical improvement of proteinuria was achieved. Hence, we diagnosed a rare secondary focal segmental glomerulosclerosis from renal cell carcinoma (paraneoplastic glomerulopathy) about which, to our knowledge, there are no previous reports. To date, there is no consensus recommendation for screening postoperative renal cell carcinoma in organ transplant recipients. The potential postoperative diagnosis of paraneoplastic glomerulopathy-associated renal cell carcinoma in kidney transplant recipients must be recognized.

Early recurrence of focal segmental glomerulosclerosis as an unusual cause of primary kidney transplant malfunction.

Recurrence of the primary disease is one of the most common causes of graft failure in the first decade after kidney transplantation. We present a case of a patient with an unusually rapid recurrence of focal segmental glomerulonephritis in the graft, the recognition of its occurrence was hampered by the primary graft affection and oligoanuria and by insignificant histological changes in the first two biopsy samples in the early post-transplant period, as well as by unawareness of the disease leading to terminal renal failure, as no renal biopsy was performed due to grade 3 obesity. Only worsening of hypoalbuminemia and finding of massive proteinuria despite oligoanuria were crucial for further management. Disease recurrence in the graft was confirmed by electron microscopy. However, complex targeted therapy did not result in restoration of graft function and decrease in proteinuria. This case history was aimed to draw attention to the knowledge of the importance of the primary disease confirmed by renal biopsy and early (so called pre-emptive) treatment in case of diseases with a high potential of recurrence (Fig. 7, Ref. 10). Text in PDF www.elis.sk Keywords: kidney transplantation, recurrence, minimal changes in glomeruli, focal segmental glomerulosclerosis.

Treatment of Focal and Segmental Glomerulosclerosis Secondary to High Altitude Polycythemia with Acetazolamide.

Vizcarra-Vizcarra, Cristhian A., Eduardo Chávez-Velázquez, Carmen Asato-Higa, and Abdías Hurtado-Aréstegui. Treatment of focal and segmental glomerulosclerosis secondary to high altitude polycythemia with acetazolamide. High Alt Med Biol. 23:286-290, 2022.-Focal segmental glomerulosclerosis (FSGS) is a morphological pattern, caused by glomerular injury and is the leading cause of nephrotic syndrome in adults. We present the case of a 59-year-old female patient, resident of a high-altitude city (3,824 m), who had polycythemia and nephrotic syndrome. A renal biopsy was performed, and the findings were compatible with FSGS. The patient received phlebotomy 500 ml three times, which reduced, partially, the hemoglobin concentration. However, she had refractory proteinuria, despite the use of enalapril and spironolactone. We observed that proteinuria worsened with the increase in hemoglobin levels. So, she was treated with acetazolamide 250 mg bid for 4 months, which reduced proteinuria and hemoglobin. During the coronavirus disease 2019 (COVID-19) pandemic, the patient did not take acetazolamide and again, she had an increase in hemoglobin and proteinuria levels. We conclude that acetazolamide may be an effective treatment in FSGS due to high altitude polycythemia.

Using Machine Learning to Identify Metabolomic Signatures of Pediatric Chronic Kidney Disease Etiology.

BACKGROUND: Untargeted plasma metabolomic profiling combined with machine learning (ML) may lead to discovery of metabolic profiles that inform our understanding of pediatric CKD causes. We sought to identify metabolomic signatures in pediatric CKD based on diagnosis: FSGS, obstructive uropathy (OU), aplasia/dysplasia/hypoplasia (A/D/H), and reflux nephropathy (RN). METHODS: Untargeted metabolomic quantification (GC-MS/LC-MS, Metabolon) was performed on plasma from 702 Chronic Kidney Disease in Children study participants (n: FSGS=63, OU=122, A/D/H=109, and RN=86). Lasso regression was used for feature selection, adjusting for clinical covariates. Four methods were then applied to stratify significance: logistic regression, support vector machine, random forest, and extreme gradient boosting. ML training was performed on 80% total cohort subsets and validated on 20% holdout subsets. Important features were selected based on being significant in at least two of the four modeling approaches. We additionally performed pathway enrichment analysis to identify metabolic subpathways associated with CKD cause. RESULTS: ML models were evaluated on holdout subsets with receiver-operator and precision-recall area-under-the-curve, F1 score, and Matthews correlation coefficient. ML models outperformed no-skill prediction. Metabolomic profiles were identified based on cause. FSGS was associated with the sphingomyelin-ceramide axis. FSGS was also associated with individual plasmalogen metabolites and the subpathway. OU was associated with gut microbiome-derived histidine metabolites. CONCLUSION: ML models identified metabolomic signatures based on CKD cause. Using ML techniques in conjunction with traditional biostatistics, we demonstrated that sphingomyelin-ceramide and plasmalogen dysmetabolism are associated with FSGS and that gut microbiome-derived histidine metabolites are associated with OU.

Renal comorbidities in collapsing variant focal segmental glomerulosclerosis: more than a coincidence?

BACKGROUND: Collapsing focal segmental glomerulosclerosis (FSGS) has various underlying etiologies and often leads to renal failure. The impact of biopsy-proven renal comorbidities in promoting collapsing glomerulopathy (CG) has not been systematically evaluated in large comparative studies. Those data are reported here. METHODS: Biopsies with the initial diagnosis of CG in native (n = 321) or transplant kidneys (n = 30) were identified in the University of North Carolina nephropathology database (1 January 2011 to 1 January 2016). Two cohorts were defined: 'sole' CG without and 'accompanied' CG with significant morphologic renal comorbidities. Tip-variant FSGS (T-FSGS) and time-matched biopsies served as control cohorts for comparative analyses. RESULTS: CG was significantly more common in native (4.4%) and transplant biopsies (4.1%) compared with T-FSGS (0.7 and <0.1%, respectively, difference versus CG P < 0.01). 'Associated' disease was significantly more common in CG (native: 151/321; 47.0%, transplant: 21/30; 70%, P < 0.05) versus T-FSGS (native: 14/51; 27.5%, transplant: exceptional; all differences versus CG P < 0.05). In native biopsies with 'accompanied' CG but not in control groups, stenosing vasculopathies including thrombotic microangiopathies were significantly more prevalent (P < 0.01). In transplants, the high incidence of 'accompanied' CG was linked to de novo diseases, mainly rejection and vascular injury. In native kidneys, membranous glomerulopathies were prevalent in 'accompanied' T-FSGS (36%) and CG (14%) (difference versus time-matched controls P < 0.01 and P < 0.05, respectively); they were uncommon in transplants. CONCLUSIONS: CG but not T-FSGS shows a high rate of comorbidities, with prominent vasculopathies presumably driving 'ischemic' CG-specific glomerular injury and also the disease course. These findings facilitate future studies into therapy, prognosis and reversibility of 'accompanied' CG.

Nephrotic syndrome with acute kidney injury due to focal segmental glomerulosclerosis following long-term treatment with minodronate.

Although bisphosphonates are well known to cause kidney disease, there are very few published cases of focal segmental glomerulosclerosis (FSGS) following treatment with minodronate. Here we report the case of an 86-year-old woman who developed acute kidney injury and nephrotic syndrome after receiving monthly oral minodronate for 24 months. Kidney biopsy revealed cellular variant FSGS. Treatment was initiated with the discontinuation of minodronate followed by intravenous methylprednisolone pulse and prednisolone at 35 mg/day. Subsequently, the patient's renal function gradually worsened, requiring initiation of hemodialysis. However, renal function and proteinuria improved markedly and hemodialysis was withdrawn 1 month after the initiation of steroid therapy. This is, to our knowledge, the first published case of FSGS induced by long-term use of minodronate, and also the first case of cellular variant FSGS induced by bisphosphonates although collapsing variant of FSGS is commonly caused by bisphosphonates. Our study indicates that patients on bisphosphonates should be closely monitored for proteinuria and renal impairment, regardless of the type of bisphosphonate.

Secreted protein acidic and rich in cysteine (SPARC) and a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1) increments by the renin-angiotensin system induce renal fibrosis in deoxycorticosterone acetate-salt hypertensive rats.

Secreted protein acidic and rich in cysteine (SPARC), an extracellular matrix (ECM) protein, was recently shown to induce collagen deposition through the production of a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1) in the aging heart. ADAMTS1 regulates ECM turnover by degrading ECM components, and its excessive activation contributes to various pathological states, including fibrosis. The present study investigated the pathophysiological regulation and role of SPARC and ADAMTS1 in renal fibrosis using uninephrectomized rats treated with deoxycorticosterone acetate (DOCA, 40 mg/kg/week, subcutaneously) and salt (1% in drinking water). The administration of DOCA and salt gradually and significantly elevated systolic blood pressure during the 3-week treatment period, induced proteinuria, decreased creatinine clearance, and increased NADPH oxidase-derived superoxide production, malondialdehyde concentrations, and monocyte chemoattractant protein-1 and osteopontin expression in the kidneys. Glomerulosclerosis, fibrillar collagen deposition, and transforming growth factor-ß expression increased in a time-dependent manner, and SPARC and ADAMTS1 expression showed a similar pattern to these changes. The angiotensin II type-1 receptor blocker losartan suppressed the overexpression of SPARC and ADAMTS1, and an in vitro exposure to angiotensin II induced the production of both SPARC and ADAMTS1 in renal fibroblast NRK-49F cells. Knockdown of the SPARC gene with small interfering RNA reduced all forms (the 110-kDa latent and 87- and 65-kDa bioactive forms) of ADAMTS1 expression as well as collagen production. These results suggest that SPARC is induced by the renin-angiotensin system and may be a fibrogenic factor, at least in part, by producing ADAMTS1 in hypertensive renal disease.

Recurrent Focal Segmental Glomerulosclerosis After Kidney Transplantation in African Americans: Review of the Current Evidence.

OBJECTIVES: In many countries of sub-Saharan Africa, the most common causes of end-stage kidney disease are hypertension, chronic glomerulonephritis, and diabetes mellitus. So far, literature on recurrent focal segmental glomerulosclerosis in sub-Saharan African populations is limited. With the intention of providing guidance for best practices in sub-Saharan Africa, we reviewed available evidence for African Americans, a population with a similar genetic background. We chose this population as a pseudo-population to show how similar genetic backgrounds can predict disease occurrence in similar populations residing in different continents. MATERIALS AND METHODS: Our extended PubMed and Scopus literature search used these key words: "focal segmental glomerulosclerosis in African Americans" (search 1), "recurrent focal segmental glomerulosclerosis after kidney transplantation" (search 2), "risk factors for recurrent focal segmental glomerulosclerosis" (search 3); and "APOL1 gene and kidney transplantation" (search 4). RESULTS/CONCLUSIONS: Search 1 yielded 4 articles, search 2 yielded 44 articles, search 3 yielded 6 articles, and search 4 yielded 8 articles. African Americans were shown to be disproportionately predisposed to endstage kidney disease, traceable to focal segmental glomerulosclerosis (the most common cause of glomerulonephritis leading to end-stage kidney disease). Apolipoprotein L1 presence in 22% of African Americans explained the odds ratio of 17 in developing focal segmental glomerulosclerosis and 8 times lifetime risk of end-stage kidney disease. Focal segmental glomerulosclerosis recurred in 30% of kidney transplant recipients; risk factors included young age, rapid progression to end-stage kidney disease, and White race recipient. Circulating permeability factors played a central role in primary and recurrent focal segmental glomerulosclerosis. For recurrent cases, transplant biopsy has remained the gold standard for diagnosis, with treatment involving a multi-modal approach, often resulting in partial or complete remission of proteinuria; allograft loss can occur if treatment is not successful. More randomized clinical trials are needed to chart the way forward for prolonged allograft function.

The Association between Glomerular Diameter and Secondary Focal Segmental Glomerulosclerosis in Chronic Kidney Disease.

INTRODUCTION: When nephron loss occurs, the glomerular filtration rate (GFR) is suggested to be maintained by glomerular hypertrophy, but excessive hypertrophy can rather lead to the formation of focal segmental glomerulosclerosis (FSGS), thereby causing progressive kidney damage. However, it is not clear how much glomerular hypertrophy leads to the formation of FSGS. We examined the association between glomerular diameter and FSGS lesions in chronic kidney disease (CKD) patients. METHODS: We recruited 77 patients who underwent renal biopsy during 2016-2017; however, those identified with primary FSGS and glomerulonephritis with active glomerular lesion were excluded. We evaluated the maximal glomerular diameter (Max GD), an indicator of glomerular size, in each renal biopsy specimen and examined its association with FSGS lesion. RESULTS: The median age, blood pressure, and estimated GFR of the patients were 53 years, 122/70 mm Hg, and 65 mL/min/1.73 m2, respectively. The optimal cutoff threshold of Max GD for predicting the presence of FSGS lesions, assessed by receiver operating characteristic curve analysis, was determined to be at 224 µm (area under the curve, 0.81; sensitivity, 81%; specificity, 72%). Multivariate logistic regression analyses demonstrated that Max GD ≥224 µm was significantly associated with the presence of FSGS lesions, independent of other confounding factors (odds ratio, 11.70; 95% confidence interval, 1.93-70.84). DISCUSSION/CONCLUSION: Glomerular hypertrophy (Max GD ≥224 µm) has been associated with FSGS lesions in CKD patients and may reflect the limits of the compensatory process.

[A secondary focal segmental glomerulosclerosis due to prematurity]. / Glomeruloesclerosis focal y segmentaria secundaria a la oligonefronia del prematuro.

INTRODUCTION: Both premature birth and low birth weight compromise nephron development. The lower nephron endowment is subjected to compensatory hyperfiltration that overloads the glomeruli and leads to the vicious circle of progressive deterioration of renal function. OBJECTIVE: To emphasize the risk of renal involvement in this susceptible population by describing the case of a patient with long-term follow-up. CLINICAL CASE: Low-weight premature newborn, who presented at 3 years of age severe hypertension, which was controlled with different types of antihypertensive drugs. However, 10 years later subnephrotic proteinuria was detected; a renal biopsy confirmed a focal and segmental glome rulosclerosis. Despite blocking the renin-angiotensin system for 23 years, his renal function progres sively deteriorated, until requiring chronic hemodialysis during the last 3 years. CONCLUSION: It is essential to increase the awareness of the risk of renal damage in premature and low weight newborns in order to establish management that covers from gestation to adult life and to achieve an individual and epidemiological impact on renal health.

Collapsing focal segmental glomerulosclerosis in a patient with oral cavity cancer: A case report.

RATIONALE: Focal segmental glomerulosclerosis (FSGS) is one of the most common glomerular diseases, leading to end-stage renal disease. Among the 5 variants of FSGS, the collapsing variant is rare and has the worst prognosis. Solid and hematologic malignancies are associated with glomerular diseases, such as membranous nephropathy, minimal change disease, and FSGS. However, squamous cell carcinoma of the oral cavity is rarely associated with nephrotic syndrome, especially FSGS. PATIENT CONCERNS: A 55-year-old woman diagnosed with oral cavity cancer presented with generalized edema with heavy proteinuria and renal dysfunction after neoadjuvant chemotherapy and wide surgical excision. DIAGNOSIS: Renal biopsy shows segmental or global collapse of glomerular capillaries with marked hyperplasia and swelling of overlying epithelial cells, suggesting a collapsing variant of FSGS. INTERVENTIONS: After the renal biopsy, we prescribed oral prednisolone at a dose of 1 mg/kg/day. Despite immunosuppressive treatment, renal function deteriorated, and hemodialysis was started. OUTCOMES: After 23 sessions of hemodialysis and high-dose oral glucocorticoid treatment, renal function gradually improved, and oral glucocorticoid therapy was discontinued after 8 months. Currently, this patient is in a cancer-free state and has normal renal function without proteinuria. LESSONS: Unusual collapsing FSGS might be associated with neoadjuvant chemotherapy and wide surgical excision in patients with oral cavity cancer. Proper diagnostic workup, such as renal biopsy and high-dose glucocorticoid therapy, might have helped recover from nephrotic syndrome and acute renal injury in cancer patients.

The effect of γ-linolenic acid on Polycystic Ovary Syndrome associated Focal Segmental Glomerulosclerosis via TGF-ß pathway.

BACKGROUND: In recent years, female infertility from Polycystic Ovary Syndrome (PCOS) has gained scientific interest. PCOS alters the metabolic and endocrine functioning in females. The elevation in androgens can damage the androgen receptors present on the kidney giving rise to renal disorders like Focal Segmental Glomerulosclerosis (FSGS). Transforming Growth Factor Beta (TGF-ß) in the ovary is activated by activin for Follicle Stimulating Hormone (FSH) secretion and in the kidney by thrombospondin 1 (TSP1) for cell growth and apoptosis. Studies show that gamma-linolenic acid (GLA) effectively treats breast cancer, eczema, inflammatory conditions and PCOS. AIM: The study aimed to find out the possibility of FSGS development in PCOS and to understand the effect of GLA on FSGS via the TGF-ß pathway. METHOD: To carry out the study, the dehydroepiandrosterone (DHEA) induced PCOS model was used. Three groups namely vehicle control, DHEA, and DHEA+GLA, were used with six animals in each. TGF-ß1, TGF-ß2, and TSP1 genes were studied using real-time PCR. RESULTS: The study showed an increase in the level of renal fibrosis biomarker, TSP1, in the DHEA group, which was further decreased by an anti-inflammatory agent, GLA. The TGF-ß1 and TGF-ß2 genes associated with the TGF-ß pathway were seen to be increased in DHEA-induced PCOS rats which showed a possible relation between the two conditions. CONCLUSION: The study shows a possible development of renal fibrosis in the DHEA-induced PCOS model. The GLA might act as a ligand to regulate TGF-ß signaling in glomerulosclerosis in a DHEA-induced PCOS model.

De novo collapsing glomerulopathy in a pediatric kidney transplant recipient with COVID-19 infection.

The negative impact of COVID-19 on adults with underlying chronic kidney disease, including kidney transplant recipients, has been well documented. Children have a less severe presentation and better prognosis compared to adults. However, little is known regarding the spectrum of COVID-19 infection in children and adolescents with underlying autoimmune disorders necessitating solid organ transplant and long-term immunosuppressive therapy. Case Report. An adolescent male developed end-stage kidney disease secondary to microscopic polyangiitis requiring a living-donor kidney transplant. Six years later, he developed antibody-mediated rejection of his kidney transplant. During his rejection treatment course, he contracted SARS-CoV-2 and developed new-onset nephrotic syndrome with severe acute kidney injury. Kidney transplant biopsy revealed de novo collapsing focal segmental glomerulosclerosis on a background of chronic active antibody mediated rejection. Immunostaining for SARS-CoV-2 on the biopsy specimen demonstrated positive staining of the proximal tubular epithelium consistent with intra-renal viral infection. Pulse corticosteroids, intravenous immunoglobulin, and temporary reduction of anti-metabolite therapy resulted in successful recovery with return of graft function back to pre-infection baseline. This case highlights the clinical conundrum of treating kidney transplant recipients with active rejection in the midst of the COVID-19 pandemic. Pediatric kidney transplant recipients can develop severe COVID-19-related kidney complications. Judicious immunosuppression modulation is necessary to balance infection and rejection risk.

Protective Role of the M-Sec-Tunneling Nanotube System in Podocytes.

BACKGROUND: Podocyte dysfunction and loss are major determinants in the development of proteinuria. FSGS is one of the most common causes of proteinuria, but the mechanisms leading to podocyte injury or conferring protection against FSGS remain poorly understood. The cytosolic protein M-Sec has been involved in the formation of tunneling nanotubes (TNTs), membrane channels that transiently connect cells and allow intercellular organelle transfer. Whether podocytes express M-Sec is unknown and the potential relevance of the M-Sec-TNT system in FSGS has not been explored. METHODS: We studied the role of the M-Sec-TNT system in cultured podocytes exposed to Adriamycin and in BALB/c M-Sec knockout mice. We also assessed M-Sec expression in both kidney biopsies from patients with FSGS and in experimental FSGS (Adriamycin-induced nephropathy). RESULTS: Podocytes can form TNTs in a M-Sec-dependent manner. Consistent with the notion that the M-Sec-TNT system is cytoprotective, podocytes overexpressed M-Sec in both human and experimental FSGS. Moreover, M-Sec deletion resulted in podocyte injury, with mitochondrial abnormalities and development of progressive FSGS. In vitro, M-Sec deletion abolished TNT-mediated mitochondria transfer between podocytes and altered mitochondrial bioenergetics. Re-expression of M-Sec reestablishes TNT formation and mitochondria exchange, rescued mitochondrial function, and partially reverted podocyte injury. CONCLUSIONS: These findings indicate that the M-Sec-TNT system plays an important protective role in the glomeruli by rescuing podocytes via mitochondrial horizontal transfer. M-Sec may represent a promising therapeutic target in FSGS, and evidence that podocytes can be rescued via TNT-mediated horizontal transfer may open new avenues of research.

Clinical and morphologic spectrum of renal involvement in idiopathic hypereosinophilic syndrome.

BACKGROUND: To explore the clinical and pathological features of renal lesions in patients with kidney involvement in idiopathic hypereosinophilic syndrome (IHES). METHODS: The demographic, clinical, and pathological characteristics and the treatment and follow-up data were analyzed. RESULTS: We identified 18 patients with IHES and renal involvement. Eleven patients presented with nephrotic syndrome, and 6 patients had impaired renal function. 15 patients underwent renal biopsy, and the pathological findings included the following: membranoproliferative glomerulonephritis in 3 patients; minimal-change disease in 3; mesangial proliferative nephritis in two; IgA nephropathy in 2; membranous nephropathy in two; chronic interstitial nephritis in two; focal segmental sclerosis in one; and eosinophil infiltration into the renal interstitium in 11 and into the glomerulus in 3. After treatment with glucocorticoids, the eosinophil count decreased. 15 patients were followed up, and 14 showed a decrease in urinary protein or renal function recovery. When glucocorticoids were discontinued, eosinophil increased (8 cases), urine protein increased (1 case), and 1 patient progressed to end-stage renal disease. CONCLUSIONS: Nephrotic syndrome with or without renal insufficiency is the main clinical manifestation. A wide spectrum of renal lesions can be observed in patients with IHES. Eosinophil infiltration into the renal interstitium was common in these patients. Most patients have a good prognosis after glucocorticoid therapy.

The Collapsing Variant of Focal Segmental Glomerulosclerosis (FSGS) Secondary to Sarcoidosis, A Very Rare Case.

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. Renal involvement in sarcoidosis patients is occurred, but the incidence and prevalence is uncertain. The most common renal involvement of systemic sarcoidosis is nephrocalcinosis and interstitial nephritis. After sarcoidosis was diagnosed in a 31-year-old male patient, we performed a renal biopsy because of nephrotic range proteinuria and renal dysfunction. The collapsing variant of focal segmental glomerulosclerosis (FSGS) secondary to sarcoidosis was diagnosed by kidney biopsy.

SRGAP1 Controls Small Rho GTPases To Regulate Podocyte Foot Process Maintenance.

BACKGROUND: Previous research demonstrated that small Rho GTPases, modulators of the actin cytoskeleton, are drivers of podocyte foot-process effacement in glomerular diseases, such as FSGS. However, a comprehensive understanding of the regulatory networks of small Rho GTPases in podocytes is lacking. METHODS: We conducted an analysis of podocyte transcriptome and proteome datasets for Rho GTPases; mapped in vivo, podocyte-specific Rho GTPase affinity networks; and examined conditional knockout mice and murine disease models targeting Srgap1. To evaluate podocyte foot-process morphology, we used super-resolution microscopy and electron microscopy; in situ proximity ligation assays were used to determine the subcellular localization of the small GTPase-activating protein SRGAP1. We performed functional analysis of CRISPR/Cas9-generated SRGAP1 knockout podocytes in two-dimensional and three-dimensional cultures and quantitative interaction proteomics. RESULTS: We demonstrated SRGAP1 localization to podocyte foot processes in vivo and to cellular protrusions in vitro. Srgap1fl/fl*Six2Cre but not Srgap1fl/fl*hNPHS2Cre knockout mice developed an FSGS-like phenotype at adulthood. Podocyte-specific deletion of Srgap1 by hNPHS2Cre resulted in increased susceptibility to doxorubicin-induced nephropathy. Detailed analysis demonstrated significant effacement of podocyte foot processes. Furthermore, SRGAP1-knockout podocytes showed excessive protrusion formation and disinhibition of the small Rho GTPase machinery in vitro. Evaluation of a SRGAP1-dependent interactome revealed the involvement of SRGAP1 with protrusive and contractile actin networks. Analysis of glomerular biopsy specimens translated these findings toward human disease by displaying a pronounced redistribution of SRGAP1 in FSGS. CONCLUSIONS: SRGAP1, a podocyte-specific RhoGAP, controls podocyte foot-process architecture by limiting the activity of protrusive, branched actin networks. Therefore, elucidating the complex regulatory small Rho GTPase affinity network points to novel targets for potentially precise intervention in glomerular diseases.