Publications by authors named "Changli Wei"

60 Publications

Soluble Urokinase Receptor and Acute Kidney Injury.

N Engl J Med 2020 01;382(5):416-426

From the Division of Cardiology, Department of Medicine, University of Michigan, Ann Arbor (S.S.H.); the Divisions of Renal Medicine (D.E.L., S. Sharma, S.S.W.) and Pulmonary and Critical Care Medicine (R.M.B.), Brigham and Women's Hospital, the Section of Nephrology, Department of Medicine, Boston University School of Medicine (S.S.W.), and the Divisions of Nephrology (S. Sever) and Cardiology (A.C., N.E.I., J.L.J.), Massachusetts General Hospital - all in Boston; Emory Clinical Cardiovascular Research Institute, Emory University School of Medicine, Atlanta (A.S.T., M.R., A.A.Q.); the Department of Medicine, Rush University Medical Center, Chicago (X.W., R.R.D., M.M.A., C.W., J.R.); the Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston (D.S.-H., J.S.-C.P., M.W.H.); and the Veterans Affairs Pittsburgh Healthcare System and the University of Pittsburgh School of Medicine, Pittsburgh (S.D.W.).

Background: Acute kidney injury is common, with a major effect on morbidity and health care utilization. Soluble urokinase plasminogen activator receptor (suPAR) is a signaling glycoprotein thought to be involved in the pathogenesis of kidney disease. We investigated whether a high level of suPAR predisposed patients to acute kidney injury in multiple clinical contexts, and we used experimental models to identify mechanisms by which suPAR acts and to assess it as a therapeutic target.

Methods: We measured plasma levels of suPAR preprocedurally in patients who underwent coronary angiography and patients who underwent cardiac surgery and at the time of admission to the intensive care unit in critically ill patients. We assessed the risk of acute kidney injury at 7 days as the primary outcome and acute kidney injury or death at 90 days as a secondary outcome, according to quartile of suPAR level. In experimental studies, we used a monoclonal antibody to urokinase plasminogen activator receptor (uPAR) as a therapeutic strategy to attenuate acute kidney injury in transgenic mice receiving contrast material. We also assessed cellular bioenergetics and generation of reactive oxygen species in human kidney proximal tubular (HK-2) cells that were exposed to recombinant suPAR.

Results: The suPAR level was assessed in 3827 patients who were undergoing coronary angiography, 250 who were undergoing cardiac surgery, and 692 who were critically ill. Acute kidney injury developed in 318 patients (8%) who had undergone coronary angiography. The highest suPAR quartile (vs. the lowest) had an adjusted odds ratio of 2.66 (95% confidence interval [CI], 1.77 to 3.99) for acute kidney injury and 2.29 (95% CI, 1.71 to 3.06) for acute kidney injury or death at 90 days. Findings were similar in the surgical and critically ill cohorts. The suPAR-overexpressing mice that were given contrast material had greater functional and histologic evidence of acute kidney injury than wild-type mice. The suPAR-treated HK-2 cells showed heightened energetic demand and mitochondrial superoxide generation. Pretreatment with a uPAR monoclonal antibody attenuated kidney injury in suPAR-overexpressing mice and normalized bioenergetic changes in HK-2 cells.

Conclusions: High suPAR levels were associated with acute kidney injury in various clinical and experimental contexts. (Funded by the National Institutes of Health and others.).
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http://dx.doi.org/10.1056/NEJMoa1911481DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065830PMC
January 2020

Soluble Urokinase Receptor and Liver Disease.

Clin Liver Dis (Hoboken) 2019 Nov 20;14(5):163-166. Epub 2019 Dec 20.

Department of Internal Medicine Rush University Medical Center Chicago IL.

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http://dx.doi.org/10.1002/cld.850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924968PMC
November 2019

Soluble Urokinase Plasminogen Activator Receptor and Decline in Kidney Function in Autosomal Dominant Polycystic Kidney Disease.

J Am Soc Nephrol 2019 07 6;30(7):1305-1313. Epub 2019 Jun 6.

Department of Medicine, Rush University Medical Center, Chicago, Illinois;

Background: Levels of soluble urokinase plasminogen activator receptor (suPAR), an inflammation marker, are strongly predictive of incident kidney disease. Patients with autosomal dominant polycystic kidney disease (ADPKD) experience progressive decline in renal function, but rates of decline and outcomes vary greatly. Whether suPAR levels are predictive of declining kidney function in patients with ADPKD is unknown.

Methods: We assessed suPAR levels in 649 patients with ADPKD who underwent scheduled follow-up for at least 3 years, with repeated measurements of height-adjusted total kidney volume and creatinine-derived eGFR. We used linear mixed models for repeated measures and Cox proportional hazards to characterize associations between baseline suPAR levels and follow-up eGFR or incident ESRD.

Results: The median suPAR level was 2.47 ng/ml and median height-adjusted total kidney volume was 778, whereas mean eGFR was 84 ml/min per 1.73 m. suPAR levels were associated with height-adjusted total kidney volume (=0.02; 95% confidence interval, 0.01 to 0.03), independent of age, sex, race, hypertension, and eGFR. Patients in the lowest suPAR tertile (<2.18 ng/ml) had a 6.8% decline in eGFR at 3 years and 22% developed CKD stage 3, whereas those in the highest tertile (suPAR>2.83 ng/ml) had a 19.4% decline in eGFR at 3 years and 68% developed CKD stage 3. suPAR levels >2.82 ng/ml had a 3.38-fold increase in the risk of incident ESRD.

Conclusions: suPAR levels were associated with progressive decline in renal function and incident ESRD in patients with ADPKD, and may aid early identification of patients at high risk of disease progression.
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http://dx.doi.org/10.1681/ASN.2018121227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6622421PMC
July 2019

uPAR isoform 2 forms a dimer and induces severe kidney disease in mice.

J Clin Invest 2019 04 2;129(5):1946-1959. Epub 2019 Apr 2.

Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA.

Soluble urokinase plasminogen activator receptor (suPAR) is an immune-derived circulating signaling molecule that has been implicated in chronic kidney disease, such as focal segmental glomerulosclerosis (FSGS). Typically, native uPAR (isoform 1) translates to a 3-domain protein capable of binding and activating integrins, yet the function of additional isoforms generated by alternative splicing is unknown. Here, we characterized mouse uPAR isoform 2 (msuPAR2), encoding domain I and nearly one-half of domain II, as a dimer in solution, as revealed by 3D electron microscopy structural analysis. In vivo, msuPAR2 transgenic mice exhibited signs of severe renal disease characteristic of FSGS with proteinuria, loss of kidney function, and glomerulosclerosis. Sequencing of the glomerular RNAs from msuPAR2-Tg mice revealed a differentially expressed gene signature that includes upregulation of the suPAR receptor Itgb3, encoding β3 integrin. Crossing msuPAR2-transgenic mice with 3 different integrin β3 deficiency models rescued msuPAR2-mediated kidney function. Further analyses indicated a central role for β3 integrin and c-Src in msuPAR2 signaling and in human FSGS kidney biopsies. Administration of Src inhibitors reduced proteinuria in msuPAR2-transgenic mice. In conclusion, msuPAR2 may play an important role in certain forms of scarring kidney disease.
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http://dx.doi.org/10.1172/JCI124793DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486353PMC
April 2019

MeSsAGe risk score: tool for renal biopsy decision in steroid-dependent nephrotic syndrome.

Pediatr Res 2019 03 15;85(4):477-483. Epub 2019 Jan 15.

Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Level 12 NUHS Tower Block, 1E Kent Ridge Road, Singapore, 119228, Singapore.

Background: A lack of consensus exists as to the timing of kidney biopsy in children with steroid-dependent nephrotic syndrome (SDNS) where minimal change disease (MCD) predominates. This study aimed at examining the applicability of a biomarker-assisted risk score model to select SDNS patients at high risk of focal segmental glomerulosclerosis (FSGS) for biopsy.

Methods: Fifty-five patients with SDNS and biopsy-proven MCD (n = 40) or FSGS (n = 15) were studied. A risk score model was developed with variables consisting of age, sex, eGFR, suPAR levels and percentage of CD8 memory T cells. Following multivariate regression analysis, total risk score was calculated as sum of the products of odds ratios and corresponding variables. Predictive cut-off point was determined using receiver operator characteristics (ROC) curve analysis.

Results: Plasma suPAR levels in FSGS patients were significantly higher, while percentage of CD45ROCD8CD3 was significantly lower than in MCD patients and controls. ROC analysis suggests the risk score model with threshold score of 16.7 (AUC 0.84, 95% CI 0.72-0.96) was a good predictor of FSGS on biopsy. The 100% PPV cut-off was >24.0, while the 100% NPV was <13.3.

Conclusion: A suPAR and CD8 memory T cell percentage-based risk score model was developed to stratify SDNS patients for biopsy and for predicting FSGS.
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http://dx.doi.org/10.1038/s41390-019-0277-zDOI Listing
March 2019

Monitoring suPAR levels in post-kidney transplant focal segmental glomerulosclerosis treated with therapeutic plasma exchange and rituximab.

BMC Nephrol 2018 12 17;19(1):361. Epub 2018 Dec 17.

Department of Medicine, Rush University Medical Center, 1735 W Harrison ST, Cohn Bldg, 7th Floor, Suite 716, Chicago, IL, 60612, USA.

Background: Therapeutic plasma exchange (TPE) is an important therapy for recurrent focal segmental glomerulosclerosis (rFSGS) post kidney transplant. suPAR has been causally implicated in rFSGS, and shown to be a unique biomarker for the occurrence and progression of chronic kidney disease. This study was targeted to evaluate the application of monitoring suPAR in TPE treated rFSGS.

Methods: A retrospective (n = 19) and a prospective (n = 15) cohort of post transplant FSGS patients treated with TPE and rituximab were enrolled. We measured serum suPAR levels before and after the combined therapies, and assessed the role of suPAR changes on proteinuria reduction and podocyte β3- integrin activity.

Results: Treatment with TPE and rituximab resulted in significant decrease in proteinuria and suPAR levels. Among the variables including baseline suPAR, serum creatinine, proteinuria, eGFR, age at diagnosis, age at transplantation, transplantation numbers, time to recurrence, and TPE course numbers, only the reduction in suPAR levels and baseline proteinuria significantly correlated with the changes in proteinuria after treatment, with the former performed better in predicting proteinuria alteration. Additionally, the mean podocyte β3 integrin activity significantly decreased after TPE and rituximab treatment (1.10 ± 0.08) as compared to before treatment (1.34 ± 0.08), p < 0.05. Only the reduction in suPAR predicted the response to therapies with an odds ratio of 1.43, 95% CI (1.02, 2.00), p < 0.05.

Conclusions: Serum suPAR levels reduced significantly after TPE and rituximab treatment in post transplant FSGS patients. The reduction in suPAR levels may be utilized to assess the changes in proteinuria and monitor the response to the therapies. Larger, multi-centered prospective studies monitoring serum suPAR levels in TPE managed post transplant FSGS are warranted.
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http://dx.doi.org/10.1186/s12882-018-1177-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296111PMC
December 2018

Runx2 is required for postnatal intervertebral disc tissue growth and development.

J Cell Physiol 2019 05 20;234(5):6679-6687. Epub 2018 Oct 20.

Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois.

Runx2 plays an essential role in embryonic disc tissue development in mice. However, the role of runt-related transcription factor 2 (Runx2) in postnatal disc tissue growth and development has not been defined. In the present studies, we generated Runx2 conditional knockout (KO) mice (Runx2 ), in which Runx2 was deleted in Aggrecan-expressing cells in disc tissue at postnatal 2-weeks of age. We then analyzed changes in disc tissue growth and development using histology and immunohistochemical methods in 3-month-old mice. We found that large vacuolated notochordal cells were accumulated in the nucleus pulposus (NP) in Runx2 KO mice. The growth plate cartilage tissue in the disc was thicker in Runx2 KO mice. We also found a significant upregulation of Indian hedgehog (Ihh) expression in the cells in NP cells and in annulus fibrosus cells of Runx2 KO mice. These results demonstrated that Runx2 may play an important role in postnatal disc tissue development through interacting with Ihh signaling.
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http://dx.doi.org/10.1002/jcp.27410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6460473PMC
May 2019

Fetal Renal Echogenicity Associated with Maternal Focal Segmental Glomerulosclerosis: The Effect of Transplacental Transmission of Permeability Factor suPAR.

J Clin Med 2018 Oct 4;7(10). Epub 2018 Oct 4.

Department of Medicine, Division of Nephrology, Sunnybrook Science Health Sciences Centre, University of Toronto, Toronto, ON M4N 3M5, Canada.

We report a case of a pregnant woman with nephrotic syndrome due to biopsy-proven focal segmental glomerulosclerosis (FSGS) whose fetus developed echogenic kidneys and severe oligohydramnios by 27 weeks of gestation. Maternal treatment with prednisone resulted in normalization of the amniotic fluid indices and resolution of fetal renal echogenicity. The newborn was noted to have transient renal dysfunction and proteinuria, resolving by 6 weeks postpartum. The transplacental passage of permeability factors is postulated to have caused both the fetal and newborn renal presentation, with significantly elevated levels of soluble urokinase-type plasminogen activator receptor (suPAR) noted in the cord blood. This case documents the transplacental maternal-fetal transmission of suPAR, demonstrating the potential for maternal-fetal transmission of deleterious, disease-causing entities, and adds to the differential diagnosis of fetal echogenic kidneys. Further, this is the first documentation of a fetal response to maternal systemic therapy.
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http://dx.doi.org/10.3390/jcm7100324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209924PMC
October 2018

Kidney-derived c-kit progenitor/stem cells contribute to podocyte recovery in a model of acute proteinuria.

Sci Rep 2018 10 3;8(1):14723. Epub 2018 Oct 3.

Interdisciplinary Stem Cell Institute, Leonard M Miller School of Medicine University of Miami, Miami, 33136, Florida, USA.

Kidney-derived c-kit cells exhibit progenitor/stem cell properties and can regenerate epithelial tubular cells following ischemia-reperfusion injury in rats. We therefore investigated whether c-kit progenitor/stem cells contribute to podocyte repair in a rat model of acute proteinuria induced by puromycin aminonucleoside (PAN), the experimental prototype of human minimal change disease and early stages of focal and segmental glomerulosclerosis. We found that c-kit progenitor/stem cells accelerated kidney recovery by improving foot process effacement (foot process width was lower in c-kit group vs saline treated animals, P = 0.03). In particular, these cells engrafted in small quantity into tubules, vessels, and glomeruli, where they occasionally differentiated into podocyte-like cells. This effect was related to an up regulation of α-Actinin-4 and mTORC2-Rictor pathway. Activation of autophagy by c-kit progenitor/stem cells also contributed to kidney regeneration and intracellular homeostasis (autophagosomes and autophagolysosomes number and LC3A/B-I and LC3A/B-II expression were higher in the c-kit group vs saline treated animals, P = 0.0031 and P = 0.0009, respectively). Taken together, our findings suggest that kidney-derived c-kit progenitor/stem cells exert reparative effects on glomerular disease processes through paracrine effects, to a lesser extent differentiation into podocyte-like cells and contribution to maintenance of podocyte cytoskeleton after injury. These findings have clinical implications for cell therapy of glomerular pathobiology.
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http://dx.doi.org/10.1038/s41598-018-33082-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6170432PMC
October 2018

Soluble urokinase-type plasminogen activator receptor and incident end-stage renal disease in Chinese patients with chronic kidney disease.

Nephrol Dial Transplant 2020 03;35(3):465-470

Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.

Background: Soluble urokinase-type plasminogen activator receptor (suPAR), a marker of immune activation, was shown to be associated with outcomes and kidney disease among various patient populations. The prognostic role of circulating suPAR levels in patients with chronic kidney disease (CKD) needs to be investigated in a cohort with large sample size of renal diseases.

Methods: We measured serum suPAR concentration in 2391 CKD patients in the multicenter Chinese Cohort Study of Chronic Kidney Disease, and investigated the association of serum suPAR with the prespecified endpoint event, end-stage renal disease (ESRD), using Cox proportional hazards regression model.

Results: Altogether, 407 ESRD events occurred during the median follow-up of 54.8 (interquartile range: 47.5-62.2) months. The higher levels of serum suPAR were independently associated with increased risk of incident ESRD after adjusting for potential confounders including the baseline estimated glomerular filtration rate categories, with the hazard ratios (HRs) of 1.53 [95% confidence intervals (CIs) 1.10-2.12] for the top tertile (≥3904 pg/mL) compared with the bottom tertile (<2532 pg/mL). When stratified by the etiologies of CKD, among patients with glomerulonephritis (GN), serum suPAR levels were also independently associated with the higher risk of ESRD, with an HR of 1.61 (95% CI 1.03-2.53) in the top tertile compared with the bottom tertile.

Conclusions: Circulating suPAR level was independently associated with an increased risk of progression to ESRD in Chinese CKD patients, especially in those with an etiology of GN.
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http://dx.doi.org/10.1093/ndt/gfy265DOI Listing
March 2020

Wnt signaling in bone, kidney, intestine, and adipose tissue and interorgan interaction in aging.

Ann N Y Acad Sci 2019 04 12;1442(1):48-60. Epub 2018 Aug 12.

Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, Illinois.

Over the last two decades, it has become increasingly apparent that Wnt signaling plays a critical role in development and adult tissue homeostasis in multiple organs and in the pathogenesis of many diseases. In particular, a crucial role for Wnt signaling in bone development and bone tissue homeostasis has been well recognized. Numerous genome-wide association studies confirmed the importance of Wnt signaling in controlling bone mass. Moreover, ample evidence suggests that Wnt signaling is essential for kidney, intestine, and adipose tissue development and homeostasis. Recent emerging evidence demonstrates that Wnt signaling may play a fundamental role in the aging process of those organs. New discoveries show that bone is not only the major reservoir for calcium and phosphate storage, but also the largest organ with multiple functions, including mineral and energy metabolism. The interactions among bone, kidney, intestine, and adipose tissue are controlled and regulated by several endocrine signals, including FGF23, klotho, sclerostin, osteocalcin, vitamin D, and leptin. Since the aging process is characterized by structural and functional decline in almost all tissues and organs, understanding the Wnt signaling-related interactions among bone, kidney, intestine, and adipose tissue in aging may shed light on the pathogenesis of age-related diseases.
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http://dx.doi.org/10.1111/nyas.13945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372353PMC
April 2019

Podocytes exhibit a specialized protein quality control employing derlin-2 in kidney disease.

Am J Physiol Renal Physiol 2018 03 22;314(3):F471-F482. Epub 2017 Nov 22.

Department of Internal Medicine, Rush University Medical Center , Chicago, Illinois.

Podocytes are terminally differentiated cells of the kidney filtration barrier with a limited proliferative capacity and are the primary glomerular target for various sources of cellular stress. Accordingly, it is particularly important for podocytes to cope with stress efficiently to circumvent cell death and avoid compromising renal function. Improperly folded proteins within the endoplasmic reticulum (ER) are associated with increased cellular injury and cell death. To relieve ER stress, protein quality control mechanisms like ER-associated degradation (ERAD) are initiated. Derlin-2 is an important dislocation channel component in the ERAD pathway, having an indispensable role in clearing misfolded glycoproteins from the ER lumen. With studies linking ER stress to kidney disease, we investigated the role of derlin-2 in the susceptibility of podocytes to injury due to protein misfolding. We show that podocytes employ derlin-2 to mediate the ER quality control system to maintain cellular homeostasis in both mouse and human glomeruli. Patients with focal segmental glomerulosclerosis (FSGS) or diabetic nephropathy (DN) upregulate derlin-2 expression in response to glomerular injury, as do corresponding mouse models. In derlin-2-deficient podocytes, compensatory responses were lost under adriamycin (ADR)-induced ER dysfunction, and severe cellular injury ensued via a caspase-12-dependent pathway. Moreover, derlin-2 overexpression in vitro attenuated ADR-induced podocyte injury. Thus derlin-2 is part of a protein quality control mechanism that can rescue glomerular injury attributable to impaired protein folding pathways in the ER. Induction of derlin-2 expression in vivo may have applications in prevention and treatment of glomerular diseases.
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http://dx.doi.org/10.1152/ajprenal.00691.2016DOI Listing
March 2018

Cardiovascular Disease Biomarkers and suPAR in Predicting Decline in Renal Function: A Prospective Cohort Study.

Kidney Int Rep 2017 May 9;2(3):425-432. Epub 2017 Feb 9.

Division of Cardiology, Emory University School of Medicine, Atlanta, Georgia, USA.

Introduction: Soluble urokinase-type plasminogen activator receptor (suPAR) strongly predicts outcomes and incident chronic kidney disease (CKD) in patients with cardiovascular disease (CVD). Whether the association between suPAR and CKD is a reflection of its overall association with chronic inflammation and poor CVD outcomes is unclear. We examined whether CVD biomarkers, including high-sensitivity C-reactive protein (hs-CRP), fibrin-degradation products (FDPs), heat-shock protein 70 (HSP-70), and high-sensitivity troponin I (hs-TnI) were associated with a decline in kidney function in the Emory Cardiovascular Biobank cohort, in which suPAR levels were shown to be predictive of both incident CKD and CVD outcomes.

Methods: We measured suPAR, hs-CRP, HSP-70, FDP, and hs-TnI plasma levels in 3282 adults (mean age 63 years, 64% male, 75% estimated glomerular filtration rate [eGFR] >60 ml/min per 1.73 m). Glomerular filtration rate was estimated using Chronic Kidney Disease-Epidemiology Collaboration (eGFR) at enrollment (n = 3282) and follow-up (n = 2672; median 3.5 years). Urine protein by dipstick at baseline was available for 1335 subjects.

Results: There was a weak correlation among biomarkers (r range: 0.17-0.28). hs-CRP, FDPs, hs-TnI, and suPAR were independently associated with baseline eGFR and proteinuria. The median yearly decline in eGFR was -0.6 ml/min per 1.73 m. hs-CRP (β: -0.04;  = 0.46), FDPs (β: -0.13;  = 0.08), HSP-70 (β: 0.05;  = 0.84), or hs-TnI (β: -0.01;  = 0.76) were associated with eGFR decline. suPAR remained predictive of eGFR decline even after adjusting for all biomarkers.

Discussion: hs-CRP, FDP, HSP-70, and hs-TnI were not associated with eGFR decline. The specific association of suPAR with eGFR decline supported its involvement in pathways specific to the pathogenesis of kidney disease.
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http://dx.doi.org/10.1016/j.ekir.2017.02.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5678674PMC
May 2017

Association of Serum Soluble Urokinase Receptor Levels With Progression of Kidney Disease in Children.

JAMA Pediatr 2017 11 6;171(11):e172914. Epub 2017 Nov 6.

Department of Medicine, Rush University Medical Center, Chicago, Illinois.

Importance: Conventional methods to diagnose and monitor chronic kidney disease (CKD) in children, such as creatinine level and cystatin C-derived estimated glomerular filtration rate (eGFR) and assessment of proteinuria in spot or timed urine samples, are of limited value in identifying patients at risk of progressive kidney function loss. Serum soluble urokinase receptor (suPAR) levels strongly predict incident CKD stage 3 in adults.

Objective: To determine whether elevated suPAR levels are associated with renal disease progression in children with CKD.

Design, Setting, And Participants: Post hoc analysis of 2 prospectively followed up pediatric CKD cohorts, ie, the ESCAPE Trial (1999-2007) and the 4C Study (2010-2016), with serum suPAR level measured at enrollment and longitudinal eGFR measured prospectively. In the 2 trials, a total of 898 children were observed at 30 (ESCAPE Trial; n = 256) and 55 (4C Study; n = 642) tertiary care hospitals in 13 European countries. Renal diagnoses included congenital anomalies of the kidneys and urinary tract (n = 637 [70.9%]), tubulointerstitial nephropathies (n = 92 [10.2%]), glomerulopathies (n = 69 [7.7%]), postischemic CKD (n = 42 [4.7%]), and other CKD (n = 58 [6.5%]). Total follow-up duration was up to 7.9 years, and median follow-up was 3.1 years. Analyses were conducted from October 2016 to December 2016.

Exposures: Serum suPAR level was measured at enrollment, and eGFR was measured every 2 months in the ESCAPE Trial and every 6 months in the 4C Study. The primary end point of CKD progression was a composite of 50% eGFR loss, eGFR less than 10 mL/min/1.73 m2, or initiation of renal replacement therapy.

Main Outcomes And Measures: The primary end point in this study was renal survival, defined as a composite of 50% loss of GFR that persisted for at least 1 month, the start of renal replacement therapy, or an eGFR less than 10 mL/min/1.73 m2.

Results: Of the 898 included children, 560 (62.4%) were male, and the mean (SD) patient age at enrollment was 11.9 (3.5) years. The mean (SD) eGFR was 34 (16) mL/min/1.73 m2. The 5-year end point-free renal survival was 64.5% (95% CI, 57.4-71.7) in children with suPAR levels in the lowest quartile compared with 35.9% (95% CI, 28.7-43.0) in those in the highest quartile (P < .001). By multivariable analysis, the risk of attaining the end point was higher in children with glomerulopathies and increased with age, blood pressure, proteinuria, and lower eGFR at baseline. In patients with baseline eGFR greater than 40 mL/min/1.73 m2, higher log-transformed suPAR levels were associated with a higher risk of CKD progression after adjustment for traditional risk factors (hazard ratio, 5.12; 95% CI, 1.56-16.7; P = .007).

Conclusions And Relevance: Patients with high suPAR levels were more likely to have progression of their kidney disease. Further studies should determine whether suPAR levels can identify children at risk for future CKD.
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http://dx.doi.org/10.1001/jamapediatrics.2017.2914DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6121753PMC
November 2017

A tripartite complex of suPAR, APOL1 risk variants and αβ integrin on podocytes mediates chronic kidney disease.

Nat Med 2017 Aug 26;23(8):945-953. Epub 2017 Jun 26.

Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA.

Soluble urokinase plasminogen activator receptor (suPAR) independently predicts chronic kidney disease (CKD) incidence and progression. Apolipoprotein L1 (APOL1) gene variants G1 and G2, but not the reference allele (G0), are associated with an increased risk of CKD in individuals of recent African ancestry. Here we show in two large, unrelated cohorts that decline in kidney function associated with APOL1 risk variants was dependent on plasma suPAR levels: APOL1-related risk was attenuated in patients with lower suPAR, and strengthened in those with higher suPAR levels. Mechanistically, surface plasmon resonance studies identified high-affinity interactions between suPAR, APOL1 and αβ integrin, whereby APOL1 protein variants G1 and G2 exhibited higher affinity for suPAR-activated avb3 integrin than APOL1 G0. APOL1 G1 or G2 augments αβ integrin activation and causes proteinuria in mice in a suPAR-dependent manner. The synergy of circulating factor suPAR and APOL1 G1 or G2 on αβ integrin activation is a mechanism for CKD.
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http://dx.doi.org/10.1038/nm.4362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019326PMC
August 2017

Soluble Urokinase Plasminogen Activator Receptor and Outcomes in Patients with Diabetes on Hemodialysis.

Clin J Am Soc Nephrol 2017 Aug 11;12(8):1265-1273. Epub 2017 May 11.

Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.

Background And Objectives: Soluble urokinase plasminogen activator receptor is a novel biomarker strongly predictive of cardiovascular outcomes implicated in the pathogenesis of kidney disease. Soluble urokinase plasminogen activator receptor levels, however, correlate with declining kidney function. It is unclear whether soluble urokinase plasminogen activator receptor levels remain associated with outcomes in patients with ESRD.

Design, Setting, Participants, & Measurements: We measured plasma soluble urokinase plasminogen activator receptor levels in 1175 patients (mean age =66±8 years old, 54% men) with type 2 diabetes mellitus on hemodialysis participating in the German Diabetes and Dialysis Study followed for a median of 4 years for outcomes including all-cause death, cardiovascular events, and infection-related mortality. Survival analysis was performed using stepwise Cox proportional hazards models adjusted for potential confounders. Also, adjustments were made for inflammatory markers (C-reactive protein and leukocyte count) and the oxidative stress marker asymmetric dimethyl arginine to investigate potential mediators of the relationship between soluble urokinase plasminogen activator receptor and outcomes.

Results: Median soluble urokinase plasminogen activator receptor levels were 10,521 pg/ml (interquartile range, 9105-12,543 pg/ml). When stratified by tertiles, patients with soluble urokinase plasminogen activator receptor >11,633 pg/ml (third tertile) had adjusted 1.6-fold higher mortality (hazard ratio, 1.60; 95% confidence interval, 1.27 to 2.03) compared with those with low soluble urokinase plasminogen activator receptor <9599 pg/ml (first tertile). Risks of sudden death and stroke were higher (adjusted hazard ratio, 1.98; 95% confidence interval, 1.27 to 3.09 and adjusted hazard ratio, 1.74; 95% confidence interval, 1.05 to 2.90, respectively), together accounting for higher incidence of cardiovascular events (adjusted hazard ratio, 1.48; 95% confidence interval, 1.15 to 1.89). Associations with outcomes persisted after adjusting for C-reactive protein, leukocyte count, and asymmetric dimethyl arginine. Addition of soluble urokinase plasminogen activator receptor to a risk factor model modestly improved risk discrimination for all-cause death ( statistic, 0.02; 95% confidence interval, 0.00 to 0.03) and cardiovascular events ( statistic, 0.02; 95% confidence interval, 0.00 to 0.05).

Conclusions: The association of soluble urokinase plasminogen activator receptor levels with outcomes persists in patients on hemodialysis. Additional study is warranted to characterize the underlying pathways of that association, which may yield opportunities to develop new therapeutic strategies.
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http://dx.doi.org/10.2215/CJN.10881016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544516PMC
August 2017

Targeting mTOR Signaling Can Prevent the Progression of FSGS.

J Am Soc Nephrol 2017 Jul 7;28(7):2144-2157. Epub 2017 Mar 7.

Department of Medicine IV, Faculty of Medicine, University of Freiburg, Germany;

Mammalian target of rapamycin (mTOR) signaling is involved in a variety of kidney diseases. Clinical trials administering mTOR inhibitors to patients with FSGS, a prototypic podocyte disease, led to conflicting results, ranging from remission to deterioration of kidney function. Here, we combined complex genetic titration of mTOR complex 1 (mTORC1) levels in murine glomerular disease models, pharmacologic studies, and human studies to precisely delineate the role of mTOR in FSGS. mTORC1 target genes were significantly induced in microdissected glomeruli from both patients with FSGS and a murine FSGS model. Furthermore, a mouse model with constitutive mTORC1 activation closely recapitulated human FSGS. Notably, the complete knockout of mTORC1 by induced deletion of both alleles accelerated the progression of murine FSGS models. However, lowering mTORC1 signaling by deleting just one allele ameliorated the progression of glomerulosclerosis. Similarly, low-dose treatment with the mTORC1 inhibitor rapamycin efficiently diminished disease progression. Mechanistically, complete pharmacologic inhibition of mTOR in immortalized podocytes shifted the cellular energy metabolism toward reduced rates of oxidative phosphorylation and anaerobic glycolysis, which correlated with increased production of reactive oxygen species. Together, these data suggest that podocyte injury and loss is commonly followed by adaptive mTOR activation. Prolonged mTOR activation, however, results in a metabolic podocyte reprogramming leading to increased cellular stress and dedifferentiation, thus offering a treatment rationale for incomplete mTOR inhibition.
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http://dx.doi.org/10.1681/ASN.2016050519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491276PMC
July 2017

Bone marrow-derived immature myeloid cells are a main source of circulating suPAR contributing to proteinuric kidney disease.

Nat Med 2017 01 12;23(1):100-106. Epub 2016 Dec 12.

Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA.

Excess levels of protein in urine (proteinuria) is a hallmark of kidney disease that typically occurs in conjunction with diabetes, hypertension, gene mutations, toxins or infections but may also be of unknown cause (idiopathic). Systemic soluble urokinase plasminogen activator receptor (suPAR) is a circulating factor implicated in the onset and progression of chronic kidney disease (CKD), such as focal segmental glomerulosclerosis (FSGS). The cellular source(s) of elevated suPAR associated with future and progressing kidney disease is unclear, but is likely extra-renal, as the pathological uPAR is circulating and FSGS can recur even after a damaged kidney is replaced with a healthy donor organ. Here we report that bone marrow (BM) Gr-1 immature myeloid cells are responsible for the elevated, pathological levels of suPAR, as evidenced by BM chimera and BM ablation and cell transfer studies. A marked increase of Gr-1 myeloid cells was commonly found in the BM of proteinuric animals having high suPAR, and these cells efficiently transmit proteinuria when transferred to healthy mice. In accordance with the results seen in suPAR-associated proteinuric animal models, in which kidney damage is caused not by local podocyte-selective injury but more likely by systemic insults, a humanized xenograft model of FSGS resulted in an expansion of Gr-1 cells in the BM, leading to high plasma suPAR and proteinuric kidney disease. Together, these results identify suPAR as a functional connection between the BM and the kidney, and they implicate BM immature myeloid cells as a key contributor to glomerular dysfunction.
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http://dx.doi.org/10.1038/nm.4242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405698PMC
January 2017

Circulating CD40 autoantibody and suPAR synergy drives glomerular injury.

Ann Transl Med 2015 Nov;3(19):300

1 Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA ; 2 Department of Surgery, University of California San Francisco, San Francisco, CA 94017, USA.

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http://dx.doi.org/10.3978/j.issn.2305-5839.2015.11.08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4671868PMC
November 2015

Soluble Urokinase Receptor and Chronic Kidney Disease.

N Engl J Med 2015 Nov 5;373(20):1916-25. Epub 2015 Nov 5.

From the Division of Cardiology, Emory Clinical Cardiovascular Research Institute, Emory University School of Medicine (S.S.H., Y.-A.K., M.A., L.S.S., S.L., A.A.Q.), and the Department of Biostatistics and Bioinformatics, Emory University (Y.-A.K.) - both in Atlanta; the Department of Medicine, Harvard Medical School, Boston, and Division of Nephrology, Massachusetts General Hospital, Charlestown - both in Massachusetts (S.S.); the Department of Pediatrics, NYU Langone Medical Center, New York (H.T.); and the Department of Medicine, Rush University Medical Center (S.W., M.M.A., C.W., A.L.F., J.R.), and the Women's Interagency HIV Study/CORE Center of Cook County (A.L.H., A.L.F.) - both in Chicago.

Background: Relatively high plasma levels of soluble urokinase-type plasminogen activator receptor (suPAR) have been associated with focal segmental glomerulosclerosis and poor clinical outcomes in patients with various conditions. It is unknown whether elevated suPAR levels in patients with normal kidney function are associated with future decline in the estimated glomerular filtration rate (eGFR) and with incident chronic kidney disease.

Methods: We measured plasma suPAR levels in 3683 persons enrolled in the Emory Cardiovascular Biobank (mean age, 63 years; 65% men; median suPAR level, 3040 pg per milliliter) and determined renal function at enrollment and at subsequent visits in 2292 persons. The relationship between suPAR levels and the eGFR at baseline, the change in the eGFR over time, and the development of chronic kidney disease (eGFR <60 ml per minute per 1.73 m(2) of body-surface area) were analyzed with the use of linear mixed models and Cox regression after adjustment for demographic and clinical variables.

Results: A higher suPAR level at baseline was associated with a greater decline in the eGFR during follow-up; the annual change in the eGFR was -0.9 ml per minute per 1.73 m(2) among participants in the lowest quartile of suPAR levels as compared with -4.2 ml per minute per 1.73 m(2) among participants in the highest quartile (P<0.001). The 921 participants with a normal eGFR (≥ 90 ml per minute per 1.73 m(2)) at baseline had the largest suPAR-related decline in the eGFR. In 1335 participants with a baseline eGFR of at least 60 ml per minute per 1.73 m(2), the risk of progression to chronic kidney disease in the highest quartile of suPAR levels was 3.13 times as high (95% confidence interval, 2.11 to 4.65) as that in the lowest quartile.

Conclusions: An elevated level of suPAR was independently associated with incident chronic kidney disease and an accelerated decline in the eGFR in the groups studied. (Funded by the Abraham J. and Phyllis Katz Foundation and others.).
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http://dx.doi.org/10.1056/NEJMoa1506362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4701036PMC
November 2015

Recurrent Primary Focal Segmental Glomerulosclerosis Managed With Intensified Plasma Exchange and Concomitant Monitoring of Soluble Urokinase-Type Plasminogen Activator Receptor-Mediated Podocyte β3-integrin Activation.

Transplantation 2015 Dec;99(12):2593-7

1 Department of Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany. 2 Department of Pathology, Charité Universitätsmedizin Berlin, Berlin, Germany. 3 Department of Medicine, Rush University Medical Center, Chicago, IL.

Background: Primary focal segmental glomerulosclerosis (FSGS) often causes nephrotic proteinuria and frequently results in end-stage renal disease and recurrence after kidney transplantation. Recent studies describe soluble urokinase-type plasminogen activator receptor (suPAR) as a circulating factor implicated in FSGS.

Methods: This single-center study included 12 adult patients with histologically proven primary FSGS (n = 2) or recurrent FSGS after transplantation (n = 10). The effect of plasma exchange (PE) on clinical outcome, suPAR levels, and in vitro podocyte β3-integrin activation was investigated over a median of 11 (6-18) sessions of PE.

Results: The course of treatment was monitored in a total of 70 sessions of PE, which partly eliminated suPAR, with a mean reduction of 37 ± 12% of serum concentration per session. However, a substantial rebound was observed between sessions, with suPAR levels reaching 99 ± 22% of the pretreatment levels after a median of 4 days. Podocyte β3-integrin activation dropped significantly after PE but rebounded within 4 days concomitant with a rising suPAR level. In 11 of 12 patients, multimodal treatment (including extensive PE) reduced proteinuria significantly (from 5.3 [2.0-7.8] to 1.0 [0.4-1.6] g/d), indicating clinical efficacy of the therapy. One patient suffered allograft loss due to FSGS recurrence. A persisting response was independent of a lasting reduction in the level of total suPAR because there was no sustained significant change in suPAR levels before and after the course of intensified treatment (3814 ± 908 to 3595 ± 521 pg/mL; P = 0.496).

Conclusions: We conclude that multimodal therapy including extensive PE was associated with stabilization of recurrent FSGS and a temporary lowering of plasma suPAR as well as podocyte β3-integrin activation. Whether a sustained lowering of total suPAR results in further improved outcomes requires additional study.
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http://dx.doi.org/10.1097/TP.0000000000000914DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4900174PMC
December 2015

Efficacy of galactose and adalimumab in patients with resistant focal segmental glomerulosclerosis: report of the font clinical trial group.

BMC Nephrol 2015 Jul 22;16:111. Epub 2015 Jul 22.

University of Michigan, Ann Arbor, MI, USA.

Background: Patients with resistant focal segmental glomerulosclerosis (FSGS) who are unresponsive to corticosteroids and other immunosuppressive agents are at very high risk of progression to end stage kidney disease. In the absence of curative treatment, current therapy centers on renoprotective interventions that reduce proteinuria and fibrosis. The FONT (Novel Therapies for Resistant FSGS) Phase II clinical trial (NCT00814255, Registration date December 22, 2008) was designed to assess the efficacy of adalimumab and galactose compared to standard medical therapy which was comprised of lisinopril, losartan, and atorvastatin.

Methods: Key eligibility criteria were biopsy confirmed primary FSGS or documentation of a causative genetic mutation, urine protein:creatinine ratio >1.0 g/g, and estimated glomerular filtration rate (eGFR) >40 ml/min/1.73 m(2). The experimental treatments - adalimumab, galactose, standard medical therapy-- were administered for 26 weeks. The primary endpoint was a 50 % reduction in proteinuria with stable eGFR.

Results: Thirty-two subjects were screened and 21 were assigned to one of the three study arms. While none of the adalimumab-treated subjects achieved the primary outcome, 2 subjects in the galactose and 2 in the standard medical therapy arm had a 50 % reduction in proteinuria without a decline in eGFR. The proteinuria response did not correlate with serial changes in the serum glomerular permeability activity measured by the Palb assay or soluble urokinase plasminogen activator receptor (suPAR). There were no serious adverse effects related to treatments in the study.

Conclusions: Recruitment into this trial that addressed patients with resistant FSGS fell short of the enrollment goal. Our findings suggest that future studies of novel therapies for rare glomerular diseases such as FSGS may benefit from enrollment of patients earlier in the course of their disease. In addition, better identification of patients who are likely to respond to a new treatment based on biomarkers suggesting involvement of the disease pathway targeted by the experimental agent may reduce the required sample size and increase the likelihood of a favorable outcome.
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http://dx.doi.org/10.1186/s12882-015-0094-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4511259PMC
July 2015

Pharmacological targeting of actin-dependent dynamin oligomerization ameliorates chronic kidney disease in diverse animal models.

Nat Med 2015 Jun 11;21(6):601-9. Epub 2015 May 11.

Department of Medicine, Harvard Medical School and Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.

Dysregulation of the actin cytoskeleton in podocytes represents a common pathway in the pathogenesis of proteinuria across a spectrum of chronic kidney diseases (CKD). The GTPase dynamin has been implicated in the maintenance of cellular architecture in podocytes through its direct interaction with actin. Furthermore, the propensity of dynamin to oligomerize into higher-order structures in an actin-dependent manner and to cross-link actin microfilaments into higher-order structures has been correlated with increased actin polymerization and global organization of the actin cytoskeleton in the cell. We found that use of the small molecule Bis-T-23, which promotes actin-dependent dynamin oligomerization and thus increased actin polymerization in injured podocytes, was sufficient to improve renal health in diverse models of both transient kidney disease and CKD. In particular, administration of Bis-T-23 in these renal disease models restored the normal ultrastructure of podocyte foot processes, lowered proteinuria, lowered collagen IV deposits in the mesangial matrix, diminished mesangial matrix expansion and extended lifespan. These results further establish that alterations in the actin cytoskeleton of kidney podocytes is a common hallmark of CKD, while also underscoring the substantial regenerative potential of injured glomeruli and identifying the oligomerization cycle of dynamin as an attractive potential therapeutic target to treat CKD.
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http://dx.doi.org/10.1038/nm.3843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4458177PMC
June 2015

A Podocyte-Based Automated Screening Assay Identifies Protective Small Molecules.

J Am Soc Nephrol 2015 Nov 9;26(11):2741-52. Epub 2015 Apr 9.

Department of Medicine, Rush University Medical Center, Chicago, Illinois;

Podocyte injury and loss mark an early step in the pathogenesis of various glomerular diseases, making these cells excellent targets for therapeutics. However, cell-based high-throughput screening assays for the rational development of podocyte-directed therapeutics are currently lacking. Here, we describe a novel high-content screening-based phenotypic assay that analyzes thousands of podocytes per assay condition in 96-well plates to quantitatively measure dose-dependent changes in multiple cellular features. Our assay consistently produced a Z' value >0.44, making it suitable for compound screening. On screening with >2100 pharmacologically active agents, we identified 24 small molecules that protected podocytes against injury in vitro (1% hit rate). Among the identified hits, we confirmed an β1-integrin agonist, pyrintegrin, as a podocyte-protective agent. Treatment with pyrintegrin prevented damage-induced decreases in F-actin stress fibers, focal adhesions, and active β1-integrin levels in cultured cells. In vivo, administration of pyrintegrin protected mice from LPS-induced podocyte foot process effacement and proteinuria. Analysis of the murine glomeruli showed that LPS administration reduced the levels of active β1 integrin in the podocytes, which was prevented by cotreatment with pyrintegrin. In rats, pyrintegrin reduced peak proteinuria caused by puromycin aminonucleoside-induced nephropathy. Our findings identify pyrintegrin as a potential therapeutic candidate and show the use of podocyte-based screening assays for identifying novel therapeutics for proteinuric kidney diseases.
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http://dx.doi.org/10.1681/ASN.2014090859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625676PMC
November 2015

A case report of adrenocorticotropic hormone to treat recurrent focal segmental glomerular sclerosis post-transplantation and biomarker monitoring.

Front Med (Lausanne) 2015 20;2:13. Epub 2015 Mar 20.

Department of Medicine, Washington University School of Medicine , St. Louis, MO , USA.

Background: Recurrent focal segmental glomerular sclerosis (rFSGS) in renal transplant recipients (RTR) is difficult to predict and treat. Early rFSGS is likely from circulating factors and preformed antibodies.

Methods: We present the case of a 23-year-old white man who presented with rFSGS and acute renal failure, requiring dialysis 9-months after a 1-haplotype matched living-related transplant. We retrospectively analyzed serum samples from various clinical stages for rFSGS biomarkers: serum glomerular albumin permeability (Palb), soluble urokinase-type plasminogen activator receptor (suPAR) serum level with suPAR-β3 integrin signaling on human podocytes, and angiotensin II type I receptor-antibody (AT1R-Ab) titer.

Results: All biomarkers were abnormal at 1-year pre-transplant prior to initiation of dialysis and at the time of transplant. After initiation of hemodialysis, β3 integrin activity on human podocytes, in response to patient serum, as well as AT1R-Ab were further elevated. At the time of biopsy-proven recurrence, all biomarkers were abnormally high. One week after therapy with aborted plasmapheresis (secondary to intolerance), and high dose steroids, the Palb and suPAR-β3 integrin activity remained significantly positive. After 12-weeks of treatment with high-dose steroids, rituximab, and galactose, the patient remained hemodialysis-dependent. Three-months after his initial presentation, we commenced adrenocorticotropic hormone (ACTH, Acthar(®) Gel), 80 units subcutaneously twice weekly. Four-weeks later, he was able to discontinue dialysis. After 8-months of maintenance ACTH therapy, his serum creatinine stabilized at 1.79 mg/dL with <1 g of proteinuria.

Conclusion: ACTH therapy was associated with improvement in renal function within 4 weeks. The use of rFSGS biomarkers may aid in predicting development of rFSGS.
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http://dx.doi.org/10.3389/fmed.2015.00013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367432PMC
April 2015

Clinical Features and Histology of Apolipoprotein L1-Associated Nephropathy in the FSGS Clinical Trial.

J Am Soc Nephrol 2015 Jun 8;26(6):1443-8. Epub 2015 Jan 8.

Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York.

Genetic variants in apolipoprotein L1 (APOL1) confer risk for kidney disease. We sought to better define the phenotype of APOL1-associated nephropathy. The FSGS Clinical Trial involved 138 children and young adults who were randomized to cyclosporin or mycophenolate mofetil plus pulse oral dexamethasone with a primary outcome of proteinuria remission. DNA was available from 94 subjects who were genotyped for APOL1 renal risk variants, with two risk alleles comprising the risk genotype. Two APOL1 risk alleles were present in 27 subjects, of whom four subjects did not self-identify as African American, and 23 of 32 (72%) self-identified African Americans. Individuals with the APOL1 risk genotype tended to present at an older age and had significantly lower baseline eGFR, more segmental glomerulosclerosis and total glomerulosclerosis, and more tubular atrophy/interstitial fibrosis. There were differences in renal histology, particularly more collapsing variants in those with the risk genotype (P=0.02), although this association was confounded by age. APOL1 risk genotype did not affect response to either treatment regimen. Individuals with the risk genotype were more likely to progress to ESRD (P<0.01). In conclusion, APOL1 risk genotypes are common in African-American subjects with primary FSGS and may also be present in individuals who do not self-identify as African American. APOL1 risk status is associated with lower kidney function, more glomerulosclerosis and interstitial fibrosis, and greater propensity to progress to ESRD. The APOL1 risk genotype did not influence proteinuria responses to cyclosporin or mycophenolate mofetil/dexamethasone.
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http://dx.doi.org/10.1681/ASN.2013111242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4446865PMC
June 2015

BDNF repairs podocyte damage by microRNA-mediated increase of actin polymerization.

J Pathol 2015 Apr 7;235(5):731-44. Epub 2015 Jan 7.

Renal Research Laboratory, Fondazione D'Amico per la Ricerca sulle Malattie Renali & Fondazione IRCCS Ca', Granda Ospedale Maggiore Policlinico, Milano, Italy.

Idiopathic focal segmental glomerulosclerosis (FSGS) is a progressive and proteinuric kidney disease that starts with podocyte injury. Podocytes cover the external side of the glomerular capillary by a complex web of primary and secondary ramifications. Similar to dendritic spines of neuronal cells, podocyte processes rely on a dynamic actin-based cytoskeletal architecture to maintain shape and function. Brain-derived neurotrophic factor (BDNF) is a pleiotropic neurotrophin that binds to the tropomyosin-related kinase B receptor (TrkB) and has crucial roles in neuron maturation, survival, and activity. In neuronal cultures, exogenously added BDNF increases the number and size of dendritic spines. In animal models, BDNF administration is beneficial in both central and peripheral nervous system disorders. Here we show that BDNF has a TrkB-dependent trophic activity on podocyte cell processes; by affecting microRNA-134 and microRNA-132 signalling, BDNF up-regulates Limk1 translation and phosphorylation, and increases cofilin phosphorylation, which results in actin polymerization. Importantly, BDNF effectively repairs podocyte damage in vitro, and contrasts proteinuria and glomerular lesions in in vivo models of FSGS, opening a potential new perspective to the treatment of podocyte disorders.
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http://dx.doi.org/10.1002/path.4484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356648PMC
April 2015

A circulating antibody panel for pretransplant prediction of FSGS recurrence after kidney transplantation.

Sci Transl Med 2014 Oct;6(256):256ra136

Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA.

Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of accelerated graft loss. To evaluate pathogenic antibodies (Abs) in rFSGS, we processed 141 serum samples from 64 patients with and without primary rFSGS and 34 non-FSGS control patients transplanted at four hospitals. We screened about 9000 antigens in pretransplant sera and selected 10 Abs targeting glomerular antigens for enzyme-linked immunosorbent assay (ELISA) validation. A panel of seven Abs (CD40, PTPRO, CGB5, FAS, P2RY11, SNRPB2, and APOL2) could predict posttransplant FSGS recurrence with 92% accuracy. Pretransplant elevation of anti-CD40 Ab alone had the best correlation (78% accuracy) with rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression in FSGS compared to non-FSGS controls. Anti-CD40 Abs purified from rFSGS patients were particularly pathogenic in human podocyte cultures. Injection of anti-CD40/rFSGS Ab enhanced suPAR (soluble urokinase receptor)-mediated proteinuria in wild-type mice, yet no sensitizing effect was noted in mice deficient in CD40 or in wild-type mice that received blocking Ab to CD40. In conclusion, a panel of seven Abs can help identify primary FSGS patients at high risk of recurrence before transplantation. Intrarenal CD40 (and possibly other specific glomerular antigens) is an important contributor to FSGS disease pathogenesis. Human trials of anti-CD40 therapies are warranted to evaluate their efficacy for preventing rFSGS and improving graft survival.
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http://dx.doi.org/10.1126/scitranslmed.3008538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394366PMC
October 2014

Case series: CTLA4-IgG1 therapy in minimal change disease and focal segmental glomerulosclerosis.

Pediatr Nephrol 2015 Mar 20;30(3):469-77. Epub 2014 Sep 20.

Division of Pediatric Nephrology, Department of Pediatrics, University of Florida, 1600 SW Archer Rd., HD214, Gainesville, FL, 32610, USA,

Background: Minimal Change Disease (MCD) in relapse is associated with increased podocyte CD80 expression and elevated urinary CD80 excretion, whereas focal segmental glomerulosclerosis (FSGS) has mild or absent CD80 podocyte expression and normal urinary CD80 excretion.

Methods: One patient with MCD, one patient with primary FSGS and three patients with recurrent FSGS after transplantation received CD80 blocking antibodies (abatacept or belatacept). Urinary CD80 and CTLA-4 levels were measured by ELISA. Glomeruli were stained for CD80.

Results: After abatacept therapy, urinary CD80 became undetectable with a concomitant transient resolution of proteinuria in the MCD patient. In contrast, proteinuria remained unchanged after abatacept or belatacept therapy in the one patient with primary FSGS and in two of the three patients with recurrent FSGS despite the presence of mild CD80 glomerular expression but normal urinary CD80 excretion. The third patient with recurrent FSGS after transplantation had elevated urinary CD80 excretion immediately after surgery which fell spontaneously before the initiation of abatacept therapy; after abatacept therapy, his proteinuria remained unchanged for 5 days despite normal urinary CD80 excretion.

Conclusion: These observations are consistent with a role of podocyte CD80 in the development of proteinuria in MCD. In contrast, CD80 may not play a role in recurrent FSGS since the urinary CD80 of our three patients with recurrent FSGS was only increased transiently after surgery and normalization of urinary CD80 did not result in resolution of proteinuria.
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http://dx.doi.org/10.1007/s00467-014-2957-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4869736PMC
March 2015

Sphingomyelinase-like phosphodiesterase 3b expression levels determine podocyte injury phenotypes in glomerular disease.

J Am Soc Nephrol 2015 Jan 12;26(1):133-47. Epub 2014 Jun 12.

Department of Medicine, Division of Nephrology and Hypertension, Peggy and Harold Katz Family Drug Discovery Center and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida;

Diabetic kidney disease (DKD) is the most common cause of ESRD in the United States. Podocyte injury is an important feature of DKD that is likely to be caused by circulating factors other than glucose. Soluble urokinase plasminogen activator receptor (suPAR) is a circulating factor found to be elevated in the serum of patients with FSGS and causes podocyte αVβ3 integrin-dependent migration in vitro. Furthermore, αVβ3 integrin activation occurs in association with decreased podocyte-specific expression of acid sphingomyelinase-like phosphodiesterase 3b (SMPDL3b) in kidney biopsy specimens from patients with FSGS. However, whether suPAR-dependent αVβ3 integrin activation occurs in diseases other than FSGS and whether there is a direct link between circulating suPAR levels and SMPDL3b expression in podocytes remain to be established. Our data indicate that serum suPAR levels are also elevated in patients with DKD. However, unlike in FSGS, SMPDL3b expression was increased in glomeruli from patients with DKD and DKD sera-treated human podocytes, where it prevented αVβ3 integrin activation by its interaction with suPAR and led to increased RhoA activity, rendering podocytes more susceptible to apoptosis. In vivo, inhibition of acid sphingomyelinase reduced proteinuria in experimental DKD but not FSGS, indicating that SMPDL3b expression levels determined the podocyte injury phenotype. These observations suggest that SMPDL3b may be an important modulator of podocyte function by shifting suPAR-mediated podocyte injury from a migratory phenotype to an apoptotic phenotype and that it represents a novel therapeutic glomerular disease target.
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http://dx.doi.org/10.1681/ASN.2013111213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4279736PMC
January 2015