Focal Segmental Glomerulosclerosis Research Articles

Role of Podocyte in Kidney Disease.

Podocytes are epithelial cells lining the outer surface of the renal glomerular capillaries and they play a pivotal role in maintaining the structural and functional integrity of the glomerular filtration barrier. Podocytes react to injury in various ways and any injury to these highly specialized cells can progress to podocyte dysfunction, resulting in a group of proteinuric renal diseases called podocytopathies. Podocytopathies include a wide spectrum of primary and secondary kidney diseases, including minimal change disease, diffuse mesangial sclerosis, focal segmental glomerulosclerosis, collapsing glomerulopathy, diabetic, membranous and lupus nephropathies. Etiologically, they can be idiopathic, genetic or secondary to infections and drugs, metabolic diseases, hemodynamic factors or associated with various immune and non-immune systemic diseases. This manuscript provides a basic understanding of podocyte structure, causes of podocyte injury, response to the injury and the subsequent progression to podocytopathies. The pathogenesis of these diseases is set around podocytes. The clinical and morphological manifestations, the commonality and heterogeneity of these podocytopathies are also discussed. As our knowledge of podocyte biology improves, so will our treatment avenues with a more podocyte-centric personalized approach.

Prevalence of Anti-PLA2R Antibodies in Biopsy Proven Membranous Nephropathy in Egyptian Patients

Abstract Background Membranous nephropathy (MN) is among the most common causes of the nephrotic syndrome in nondiabetic adults, accounting for approximately 20 to 30 percent of cases of nephrotic syndrome in White adults. MN is most often primary (previously called idiopathic), although it may be secondary with hepatitis B infection, autoimmune diseases as systemic lupus erythematosus (SLE), malignancies, and the use of certain drugs such as nonsteroidal antiinflammatory drugs (NSAIDs). MN in young females should raise the suspicion of SLE. Aim of the Work The aim of this work was to study the prevalence of anti-PLA2R antibodies in Egyptian patients with biopsy proven membranous nephropathy. Patients and Methods Our cross-sectional study included 70 Egyptian patients with nephrotic range proteinuria on first presentation for whom laboratory investigations including serum anti- PLA2R antibodies titer by indirect immunoflouresence and kidney biopsy were done. Results Membranous nephropathy has been diagnosed in 35.71% of adult Egyptian patients presented with nephrotic range proteinuria. 84% of the cases of membranous nephropathy had been diagnosed with primary membranous nephropathy and 16% diagnosed with secondary membranous nephropathy. Sensitivity of circulating anti-PLA2R antibodies in primary MN was 42.85% versus 80.95% for its detection within the glomerular extracts. Specificity of PLA2R is close to 100%; however, in other studies; PLA2R has been detected in the immune deposits of some patients with secondary MN. Patients with high anti-PLA2R titer had higher baseline proteinuria than patients with lower anti-PLA2R titer. Conclusion Membranous nephropathy (primary and secondary) may be considered the most common glomerulonephritis by biopsy finding in patients presenting with nephrotic range proteinuria followed by focal segmental glomerulosclerosis (35.7 %& 30% respectively). 84% of the cases of membranous nephropathy had been diagnosed with primary membranous nephropathy and 16% had been diagnosed with secondary membranous nephropathy. Circulating anti-PLA2R antibodies were detected within serum in 42.85% of primary MN cases while detection of anti- PLA2R antibodies within the glomerular extracts of primary MN cases was much higher (80.95%). Specificity of PLA2R is close to 100%; however, in other studies; PLA2R has been detected in the immune deposits of some patients with secondary MN. Patients with high anti-PLA2R titer had higher baseline proteinuria than patients with lower anti-PLA2R titer.

Outcome of Glomerular Disease Manifesting After Vaccination Against Severe Acute Respiratory Syndrome Coronavirus 2.

Introduction Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can upregulate the immune system and may contribute to glomerular disease (GD). Here, we describe a spectrum of GD that manifested following vaccination against SARS-CoV-2 (COVID-19 vaccinations). Material and methods This was a descriptive study of 10 cases enrolled between January 2021 and January 2023. Patients with biopsy-proven GD that manifested following COVID-19 vaccinations were included. Results We found 10 cases of biopsy-proven GD following the COVID-19 vaccination. This included five cases of minimal change disease (MCD), three cases of focal segmental glomerulosclerosis (FSGS), one case of C3 glomerulonephritis (C3GN), and one case of IgA nephropathy (IgAN). The pre-existing disease was found in the last two patients (IgAN and C3GN) who got unmasked following vaccination. We did not observe any relation between vaccine type (Covisheld; six cases vs. Covaxin; four cases) and GD. In most cases (8/10 cases, 80.0%), GD developed after a repeat dose (second or booster dose). The onset time following vaccination was typically less than a week, and even less following a repeat dose. Conclusion Post-vaccination GD can be either de novo or a flare-up of a pre-existing one. The onset time following vaccination was typically less than a week for both Covishield and Covaxin.

Role of TSP-1 and its receptor ITGB3 in the renal tubulointerstitial injury of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS), a common cause of primary glomerulonephritis, has a poor prognosis and is pathologically featured by tubulointerstitial injury. Thrombospondin-1 (TSP-1) is an extracellular matrix protein that acts in combination with different receptors in the kidney. Here, we analyzed the tubular expression of TSP-1 and its receptor integrin β3 (ITGB3) in FSGS. Previously the renal interstitial chip analysis of FSGS patients with tubular interstitial injury showed that the expressions of TSP-1 and ITGB3 were up-regulated. We found that the level of TSP-1 and ITGB3 increased in the tubular cells of FSGS patients. The serum level of TSP-1 increased and was correlated to the degree of tubulointerstitial lesions in FSGS patients. THBS1/ITGB3 signaling induced renal tubular injury in HK-2 cells exposure to BSA and the ADR-induced nephropathy model. THBS1 knockout ameliorated tubular injury and renal fibrosis in ADR-treated mice. THBS1 knockdown decreased the expression of KIM-1 and caspase 3 in the HK-2 cells treated with BSA, while THBS1 overexpression could induce tubular injury. In vivo, we identified cyclo-RGDfK as an agent to block the binding of TSP-1 to ITGB3. Cyclo-RGDfK treatment could alleviate ADR-induced renal tubular injury and interstitial fibrosis in mice. Moreover, TSP-1 and ITGB3 were colocalized in tubular cells of FSGS patients and ADR-treated mice. Taken together, our data showed that TSP-1/ITGB3 signaling contributed to the development of renal tubulointerstitial injury in FSGS, potentially identifying a new therapeutic target for FSGS.

Unmasking the Silent Threat: COVID-19's Pervasive Impact on Renal Allografts.

Growing evidence has highlighted the substantial effects of COVID-19 on kidneys, ranging from mild proteinuria to severe acute kidney injury. However, comprehensive assessments of histopathological features in renal allograft biopsies are lacking. Seventeen kidney transplant recipients with COVID-19 between March 2020 and November 2022 were evaluated. Clinical characteristics, pathological findings, and outcomes were studied. Six kidney transplant recipients (35.3%) developed acute kidney injury, leading to the requirement for hemodialysis. COVID-19 severity, as indicated by pneumonia (P = .028) and hospitalization (P = .002), was significantly associated with development of acute kidney injury. Most patients with COVID-19 (82.4%) showed considerably increased proteinuria levels (82.4%), along with presence of new-onset microscopic hematuria (35.3%) and nephrotic syndrome (58.8%). Tubular viral inclusionlike changes were detected in 47.1% of cases and were associated with a higher risk of graft loss (75%). Thrombotic microangiopathy and endothelial cell swelling in glomeruli were prevalent, highlighting extensive endothelial cell injury. Most recipients (88.2%) experienced rejection after COVID-19, with graft loss occurring in 46.7% of these cases. Biopsies revealed collapsing (n = 5), noncollapsing (n = 3), and recurrent (n = 2) focal segmental glomerulosclerosis, as well as acute tubulointerstitial nephritis (n = 3), crescentic glomerulonephritis with immunoglobulin A nephropathy (n = 1), and membranoproliferative glomerulonephritis (n = 1), in 129.7 ± 33 days. Eight patients experienced graft loss (8.2 ± 2 mo posttransplant). Hospitalization (P = .044) and viralinclusion-like nuclear changes in tubules (P = .044) significantly influenced graft survival. Collapsing (60%) and noncollapsing (66.7%) focal segmental glomerulosclerosis increased the risk of graft loss. COVID-19 has had a multifaceted and enduring effect on renal allografts, urging the need for meticulous monitoring and tailored management strategies to mitigate the risk of severe kidney-related complications and graft loss in this vulnerable population.

Incorporating genetic testing into a routine kidney clinic.

Incorporating genetic testing in routine outpatient nephrology clinic can improve on chronic kidney disease (CKD) diagnosis and utilization of precision medicine. We sent a genetic test on patients with atypical presentation of common kidney diseases, electrolytes derangements, and cystic kidney diseases. We were able to identify a gene variant contributing to patients' kidney disease in more than half of our cohort. We then showed that patients with ApoL1 risk allele have likely worse kidney disease, and we were able to confirm genetic focal segmental glomerulosclerosis (FSGS) in 2 patients and avoid unnecessary immunosuppression. Genetic testing has also improved our operation to establish a polycystic kidney disease excellence center by confirming our diagnosis, especially in patients without a well-defined family history. In conclusion, utilizing genetic testing in a routine outpatient renal clinic did not cause any burden to either patients or nephrologists, with minimal administrative effort and no financial cost to our patients. We expect that genetic testing in the right setting should become routine in nephrology to achieve a patient-centered precision medicine with less invasive means of kidney disease diagnosis.

The role of matrix metalloproteinase inhibitor (doxycycline) in the treatment of primary focal segmental glomerulosclerosis

Background Focal and segmental glomerulosclerosis (FSGS) is a histological pattern used in clinical practice to define a podocytopathy that develops with nephrotic-range proteinuria and segmental obliteration or collapse of glomerular capillary loops with increased extracellular matrix in some glomeruli. The major concerns of idiopathic FSGS are the poor renal prognosis with an absence of response to immunosuppressive therapies or relapses and its recurrence after kidney transplantation in ⁓30–50% of patients, which leads to renal graft failure. The aim of this work is to study the possible role of matrix metalloproteinase inhibitor (doxycycline) in the treatment of primary FSGS. Patients and methods This prospective cohort study was conducted on 100 patients with FSGS. Patients were randomly divided into two equal groups: group 1: patients with FSGS under conventional therapy as a control group. Group 2: patients with FSGS under conventional therapy and doxycycline 100 mg/day for 3 months. Patients were closely monitored for treatment effects and adverse reactions. Clinical, laboratory, and radiological parameters were assessed. Treatment outcomes, including remission of proteinuria and adverse effects, were evaluated. Results Group 2 showed significantly lower levels of triglycerides and fasting blood glucose compared with group 1. Doxycycline-related side effects were observed in some group 2 patients. Both groups showed increased hemoglobin levels and decreased C-reactive protein levels at follow-up. Kidney function tests improved in both groups, with group 2 demonstrating superior outcomes. Group 2 showed higher rates of improvement and lower incidence of end-stage renal disease requiring hemodialysis. Conclusion Adding doxycycline to conventional therapy holds promise for treating primary FSGS. Patients receiving combined therapy exhibited enhanced renal function, reduced proteinuria, and better treatment outcomes.

An Unusual Glomerulopathy with Subepithelial Deposits Having Microspherular Structures Following COVID-19 Vaccine

We report an unusual glomerulopathy with nephrotic syndrome and acute kidney injury almost two weeks after the second injection of SARS CoV-2 vaccine covishield, ChAdOx1-nCoV-19 in a 75-year-old healthy man. Kidney biopsy revealed segmental stage 1 membranous glomerulopathy and collapsing focal segmental glomerulosclerosis pattern with immune complexes on IF. Electron microscopy (EM) revealed aggregates of spherular microparticles along glomerular capillary walls. After starting him on steroids, his kidney functions gradually improved with significantly reduced proteinuria. Our patient seems to be the only reported SARS CoV-2 vaccine-induced early membranous nephropathy showing a collapsing focal segmental glomerulosclerosis pattern and immune complexes on IF with subepithelial deposits consisting of microspherular particles on EM.

Disseminated Histoplasmosis with Secondary Hemophagocytic Lymphohistiocytosis in a Renal Transplant Recipient on Belatacept-based Immunosuppression

Effective post-transplant immunosuppression is essential to induce tolerance to allogeneic tissues and promote long-term graft survival. However, suppression of the immune system significantly increases the risk of opportunistic infections. In addition to the ongoing challenge of balancing graft survival and preventing infections, previous gold-standard calcineurin inhibitor-based immunosuppression also posed an increased risk of nephrotoxicity, cardiac disease, and diabetes. Belatacept is approved as an alternative to calcineurin inhibitor-based regimens. Although belatacept has improved cardiovascular and metabolic adverse events in renal transplant patients’ but it carries a notably higher risk of long-term graft survival and renal toxicity, similar to calcineurin inhibitor-based regimens. However, there may be an increased risk of infections with its mechanism of action. We present a case of a 62-year-old female who developed disseminated histoplasmosis 18 months after being on belatacept-based immunosuppression after a deceased donor renal transplant for end-stage renal disease secondary to focal segmental glomerulosclerosis. Grocott Methenamine Stain (GMS) of peripheral blood smear showed intracellular yeast in neutrophils, consistent with histoplasmosis. Disseminated histoplasmosis was confirmed with positive bronchoalveolar lavage (BAL) and urine culture. The patient later developed hemophagocytic lymphohistiocytosis (HLH) secondary to immunosuppression and disseminated histoplasmosis. The patient succumbed to the disease despite maximal medical therapy. To our knowledge, there is one other published report of disseminated histoplasmosis in a patient with belatacept-based immunosuppression. The unique feature of this case is the development of HLH secondary to disseminated histoplasmosis while on belatacept. Further research is needed to evaluate the need for antifungal prophylaxis in patients on belatacept therapy.

Value of urinary CD80 in differentiating minimal change disease from focal segmental glomerulosclerosis

Background. Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are two common forms of childhood nephrotic syndrome (NS). Separating MCD from FSGS is essential to determine the treatment therapy and the prognosis. Cluster of differentiation 80 (CD80) in urine is now considered a valuable marker for detecting MCD. Therefore, we conducted this research to evaluate the role of urinary CD80 concentrations in differentiating MCD from FSGS. Methods. A cross-sectional descriptive study was performed on 67 children with NS who underwent kidney biopsy and 67 children in the control group. Results. MCD accounted for the majority (61.2%), while FSGS accounted for 38.8% with an MCD/FSGS ratio of 1.6:1. There were no significant differences in age, gender, hematuria, hypertension, urinary protein-creatinine ratio, and albumin concentrations between the two study groups (p>0.05). There were statistically significant differences in glomerular filtration rate (GFR) between the two study groups with p<0.05. The urinary CD80/creatinine ratio in the MCD group was 25.6 (5.4-38.3) pg/µmol, which was significantly higher than that of the FSGS group (3.6 (1.9-6.5) pg/µmol) with p<0.05. The area under the ROC curve for urinary CD80/creatinine ratio in the diagnosis of MCD with FSGS was 0.87 (95% CI 0.79-0.95) at a cut-off value of 4.6 pg/µmol, with a sensitivity of 85.4% and specificity of 73.1%, p<0.05. Conclusion. The urinary CD80/creatinine ratio was useful in differentiating between nephrotic syndrome with MCD and FSGS.

Design and Rationale of the Phase 2 Baricitinib Study in Apolipoprotein L1–Mediated Kidney Disease (JUSTICE)

Individuals of recent West African ancestry develop focal segmental glomerulosclerosis (FSGS) and hypertension-attributed end-stage kidney disease (HTN-ESKD) at 4 times the rate of White Americans. Two protein-coding variants of the Apolipoprotein L1 (APOL1) gene, G1 and G2, explain 50% to 70% of the excess risk of HTN-ESKD and FSGS among this group. Increased expression of G1 and G2 in the kidney, mediated by Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling, drive pathogenesis of these kidney diseases. Baricitinib is an orally active inhibitor of JAK1/2 that blocks APOL1 synthesis. The Janus kinase-STAT Inhibition to Reduce APOL1-Associated Kidney Disease (JUSTICE) trial is evaluating the antiproteinuric efficacy and safety of baricitinib in patients with APOL1-associated FSGS and HTN-attributed chronic kidney disease (HTN-CKD). JUSTICE is a single-center, randomized, double-blind, placebo-controlled, pilot phase 2 trial of baricitinib in patients with proteinuria, APOL1-associated FSGS or APOL1-associated HTN-CKD without diabetes. A total of 75 African American patients with APOL1-associated CKD, including 25 with FSGS and 50 with HTN-CKD, aged 18 to 70 years will be randomized 2:1 to daily treatment with baricitinib or placebo, respectively. The primary efficacy end point will be percent change in urine albumin-to-creatinine ratio (UACR) from baseline to end of month 6. The primary safety end point will be incidence of clinically significant decreases in hemoglobin of≥ 1g/dl. The phase 2 JUSTICE study will characterize the antiproteinuric efficacy and safety of JAK1/2 inhibition with baricitinib in patients with APOL1-associated FSGS and APOL1-associated HTN-CKD.

INF2 formin variants linked to human inherited kidney disease reprogram the transcriptome, causing mitotic chaos and cell death

Mutations in the human INF2 gene cause autosomal dominant focal segmental glomerulosclerosis (FSGS)—a condition characterized by podocyte loss, scarring, and subsequent kidney degeneration. To understand INF2-linked pathogenicity, we examined the effect of pathogenic INF2 on renal epithelial cell lines and human primary podocytes. Our study revealed an increased incidence of mitotic cells with surplus microtubule-organizing centers fostering multipolar spindle assembly, leading to nuclear abnormalities, particularly multi-micronucleation. The levels of expression of exogenous pathogenic INF2 were similar to those of endogenous INF2. The aberrant nuclear phenotypes were observed regardless of the expression method used (retrovirus infection or plasmid transfection) or the promoter (LTR or CMV) used, and were absent with exogenous wild type INF2 expression. This indicates that the effect of pathogenic INF2 is not due to overexpression or experimental cell manipulation, but instead to the intrinsic properties of pathogenic INF2. Inactivation of the INF2 catalytic domain prevented aberrant nuclei formation. Pathogenic INF2 triggered the translocation of the transcriptional cofactor MRTF into the nucleus. RNA sequencing revealed a profound alteration in the transcriptome that could be primarily attributed to the sustained activation of the MRTF-SRF transcriptional complex. Cells eventually underwent mitotic catastrophe and death. Reducing MRTF-SRF activation mitigated multi-micronucleation, reducing the extent of cell death. Our results, if validated in animal models, could provide insights into the mechanism driving glomerular degeneration in INF2-linked FSGS and may suggest potential therapeutic strategies for impeding FSGS progression.

Kidney involvement in ankylosing spondylitis; recent findings

Ankylosing spondylitis is a chronic inflammatory illness that initially involves the spine and sacroiliac joint. It rarely presents with kidney disease. Various biochemical and morphological alterations have been described, consisting of hematuria, proteinuria, and low GFR across immunoglobulin A nephropathy, renal amyloidosis, focal segmental glomerulosclerosis, and chronic interstitial nephritis with different frequencies among populations.

Cathepsin S (CTSS) in IgA nephropathy: an exploratory study on its role as a potential diagnostic biomarker and therapeutic target.

IgA nephropathy (IgAN), a prevalent form of glomerulonephritis globally, exhibits complex pathogenesis. Cathepsins, cysteine proteases within lysosomes, are implicated in various physiological and pathological processes, including renal conditions. Prior observational studies have suggested a potential link between cathepsins and IgAN, yet the precise causal relationship remains unclear. We conducted a comprehensive bidirectional and multivariable Mendelian randomization (MR) study using publicly available genetic data to explore the causal association between cathepsins and IgAN systematically. Additionally, immunohistochemical (IHC) staining and enzyme-linked immunosorbent assay (ELISA) were employed to evaluate cathepsin expression levels in renal tissues and serum of IgAN patients. We investigated the underlying mechanisms via gene set variation analysis (GSVA), gene set enrichment analysis (GSEA), and immune cell infiltration analysis. Molecular docking and virtual screening were also performed to identify potential drug candidates through drug repositioning. Univariate MR analyses demonstrated a significant link between increased cathepsin S (CTSS) levels and a heightened risk of IgAN. This was evidenced by an odds ratio (OR) of 1.041 (95% CI=1.009-1.073, P=0.012) as estimated using the inverse variance weighting (IVW) method. In multivariable MR analysis, even after adjusting for other cathepsins, elevated CTSS levels continued to show a strong correlation with an increased risk of IgAN (IVW P=0.020, OR=1.037, 95% CI=1.006-1.069). However, reverse MR analyses did not establish a causal relationship between IgAN and various cathepsins. IHC and ELISA findings revealed significant overexpression of CTSS in both renal tissues and serum of IgAN patients compared to controls, and this high expression was unique to IgAN compared with several other primary kidney diseases such as membranous nephropathy, minimal change disease and focal segmental glomerulosclerosis. Investigations into immune cell infiltration, GSEA, and GSVA highlighted the role of CTSS expression in the immune dysregulation observed in IgAN. Molecular docking and virtual screening pinpointed Camostat mesylate, c-Kit-IN-1, and Mocetinostat as the top drug candidates for targeting CTSS. Elevated CTSS levels are associated with an increased risk of IgAN, and this enzyme is notably overexpressed in IgAN patients' serum and renal tissues. CTSS could potentially act as a diagnostic biomarker, providing new avenues for diagnosing and treating IgAN.

Lupus-associated collapsing glomerulopathy; a current data

Collapsing glomerulopathy is a rare but severe form of glomerular injury that can be accompanying by SLE (systemic lupus erythematosus). The pathogenesis of collapsing glomerulopathy in lupus is not well understood, and the treatment options are limited. The treatment of collapsing glomerulopathy in lupus is challenging. Immunosuppressive therapy with corticosteroids and cytotoxic agents is the mainstay of treatment. However, the response to therapy is often poor, and many patients progress to end-stage renal disease despite treatment. The use of newer agents such as rituximab and belimumab may offer additional options for the treatment of collapsing glomerulopathy in lupus. Further studies are required to better detect the underlying mechanisms of collapsing glomerulopathy in lupus and to develop more effective therapies for this condition.

C4d expression in focal segmental glomerulosclerosis

BackgroundThere is a little information about of expression of C4d (complement fragment) in Focal segmental glomerulosclerosis (FSGS) subtypes. Our aim was to determine the expression of C4d in FSGS subtypes in percutaneous native renal biopsies in a second-level hospital and its correlation with clinical, biochemical and histological variables. Material and methodsA retrospective study in paraffin blocks of patients with biopsy with FSGS aged 16–65 years, indistinct sex, not diabetic or obese. Immunohistochemistry was performed for C4d and their expression was analyzing in non-sclerosed glomerular capillaries (GC) and sclerosis areas (SA). Clinical and biochemical variables were recorded. The cases were divided into C4d positive and C4d negative groups and compared. The correlation between C4d staining scores in CG and SA with clinical and biochemical variables were analyzed. ResultsTwenty samples were analyzed, 4 for each subtype. At the time of biopsy average age 38.8 ± 18.6 years, 65% male, 8.7% were hypertension. The percentage of positivity for C4d was 40% in GC, 30% SA and 35% in mesangium. The highest expression was for cellular and collapsing subtypes. C4d positivity cases had increased proteinuria (p = 0.035). A significant correlation was found between percentage of C4d expression in CG with SA (p = 0.012) and SA with tubular atrophy and interstitial fibrosis (p < 0.05). ConclusionsC4d expression in FSGS predominated in the cellular and collapsing subtypes, which translates complement activation. C4d is a possible surrogate marker in GSFS.

A Rare Case of Tuberculosis Masquerading as Collapsing Glomerulopathy

Collapsing glomerulopathy (CG), usually presents with renal dysfunction, hypertension and proteinuria. The etiology is uncertain, yet a number of associations, including many viral infections commonly have been reported. Tuberculosis (TB), one of the most common infections, is not known to cause CG. We report a case of severe renal dysfunction requiring dialysis who had collapsing glomerulopathy on biopsy and evidence of active pulmonary tuberculosis. Anti-tubercular therapy alone resulted in improvement in kidney function.

SA27 Reduction in Corticosteroid Use Among Patients With Focal Segmental Glomerulosclerosis, Membranous Nephropathy, or IgA Nephropathy after Acthar® Gel in a Large Administrative Claims Database

SA27 Reduction in Corticosteroid Use Among Patients With Focal Segmental Glomerulosclerosis, Membranous Nephropathy, or IgA Nephropathy after Acthar® Gel in a Large Administrative Claims Database

Evaluation of pathogenicity of WT1 intron variants by in vitro splicing analysis.

Wilms tumor 1 (WT1; NM_024426) causes Denys-Drash syndrome, Frasier syndrome, or isolated focal segmental glomerulosclerosis. Several WT1 intron variants are pathogenic; however, the pathogenicity of some variants remains undefined. Whether a candidate variant detected in a patient is pathogenic is very important for determining the therapeutic options for the patient. In this study, we evaluated the pathogenicity of WT1 gene intron variants with undetermined pathogenicity by comparing their splicing patterns with those of the wild-type using an in vitro splicing assay using minigenes. The three variants registered as likely disease-causing genes: Mut1 (c.1017-9T > C(IVS5)), Mut2 (c.1355-28C > T(IVS8)), Mut3 (c.1447 + 1G > C(IVS9)), were included as subjects along the 34 splicing variants registered in the Human Gene Mutation Database (HGMD)®. The results showed no significant differences in splicing patterns between Mut1 or Mut2 and the wild-type; however, significant differences were observed in Mut3. We concluded that Mut1 and Mut2 do not possess pathogenicity although they were registered as likely pathogenic, whereas Mut3 exhibits pathogenicity. Our results suggest that the pathogenicity of intronic variants detected in patients should be carefully evaluated.

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.