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Concept: Proteinuria

195

Abatacept (cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin fusion protein [CTLA-4-Ig]) is a costimulatory inhibitor that targets B7-1 (CD80). The present report describes five patients who had focal segmental glomerulosclerosis (FSGS) (four with recurrent FSGS after transplantation and one with primary FSGS) and proteinuria with B7-1 immunostaining of podocytes in kidney-biopsy specimens. Abatacept induced partial or complete remissions of proteinuria in these patients, suggesting that B7-1 may be a useful biomarker for the treatment of some glomerulopathies. Our data indicate that abatacept may stabilize β1-integrin activation in podocytes and reduce proteinuria in patients with B7-1-positive glomerular disease.

Concepts: Protein, Glomerulus, Nephron, Nephrotic syndrome, Proteinuria, Focal segmental glomerulosclerosis, Glomerulosclerosis, CTLA-4

177

Genetic diversity across different human populations can enhance understanding of the genetic basis of disease. We calculated the genetic risk of 102 diseases in 1,043 unrelated individuals across 51 populations of the Human Genome Diversity Panel. We found that genetic risk for type 2 diabetes and pancreatic cancer decreased as humans migrated toward East Asia. In addition, biliary liver cirrhosis, alopecia areata, bladder cancer, inflammatory bowel disease, membranous nephropathy, systemic lupus erythematosus, systemic sclerosis, ulcerative colitis, and vitiligo have undergone genetic risk differentiation. This analysis represents a large-scale attempt to characterize genetic risk differentiation in the context of migration. We anticipate that our findings will enable detailed analysis pertaining to the driving forces behind genetic risk differentiation.

Concepts: Human Genome Project, Rheumatology, Ulcerative colitis, Corticosteroid, Systemic lupus erythematosus, Lupus erythematosus, Autoimmune diseases, Proteinuria

29

Alendronate is a widely used bisphosphonate in the treatment of osteoporosis. Although it has been proven to be a very useful drug, it has some side effects as well. In this paper, we describe a case of nephrotic syndrome due to alendronate administration. A 36-year-old man was admitted to the nephrology outpatient clinic with widespread edema 4 months after initiation of alendronate. He had a 13-kg weight gain within a 2-week period. He had no clinical or laboratory problems apart from osteoporosis, which was the indication for initiation of the drug. Physical examination at admission was unremarkable, but for nephrotic edema. Laboratory studies revealed nephrotic range proteinuria (13.5 g/day), normal renal function, hypoalbuminemia (1.7 g/dl), and also hypercholesterolemia (400 mg/dl). A kidney biopsy was performed. Light microscopic evaluation revealed a slight increase in mesangial cells and matrix; however, no abnormalities in the tubules or interstitium were noted. Alendronate was withdrawn and diuretic therapy was initiated. Patient’s weight gradually decreased from 84 to 67 kg within a 1-week period. No other drugs for the treatment of nephrotic syndrome were administered. During the clinical course, serum creatinine remained stable, and proteinuria gradually decreased and disappeared 40 days after stopping alendronate. It was noted that alendronate administration can give rise to nephrotic syndrome, while discontinuation of this drug may improve the pathology without any specific treatment.

Concepts: Bisphosphonate, Renal failure, Kidney, Nephrology, Renal physiology, Nephrotic syndrome, Proteinuria, Nephritic syndrome

28

Overexpression of soluble urokinase receptor (suPAR) causes pathology in animal models similar to primary FSGS, and one recent study demonstrated elevated levels of serum suPAR in patients with the disease. Here, we analyzed circulating suPAR levels in two cohorts of children and adults with biopsy-proven primary FSGS: 70 patients from the North America-based FSGS clinical trial (CT) and 94 patients from PodoNet, the Europe-based consortium studying steroid-resistant nephrotic syndrome. Circulating suPAR levels were elevated in 84.3% and 55.3% of patients with FSGS patients in the CT and PodoNet cohorts, respectively, compared with 6% of controls (P<0.0001); inflammation did not account for this difference. Multiple regression analysis suggested that lower suPAR levels associated with higher estimated GFR, male sex, and treatment with mycophenolate mofetil. In the CT cohort, there was a positive association between the relative reduction of suPAR after 26 weeks of treatment and reduction of proteinuria, with higher odds for complete remission (P=0.04). In the PodoNet cohort, patients with an NPHS2 mutation had higher suPAR levels than those without a mutation. In conclusion, suPAR levels are elevated in geographically and ethnically diverse patients with FSGS and do not reflect a nonspecific proinflammatory milieu. The associations between a change in circulating suPAR with different therapeutic regimens and with remission support the role of suPAR in the pathogenesis of FSGS.

Concepts: Immune system, Regression analysis, Clinical trial, Pathology, Nephrotic syndrome, Proteinuria, Mycophenolic acid, Focal segmental glomerulosclerosis

27

BACKGROUND: The study was undertaken to develop a potential new markers for distinguishing minimal change nephrotic syndrome (MCNS) and focal segmental glomerulosclerosis (FSGS) in children. We hypothesized that matrix metalloproteinase-9/neutrophil gelatinase-associated lipocalin (MMP-9/NGAL) is a better marker of focal sclerosis in the glomerulus then matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 (MMP-9/TIMP-1) and matrix metalloproteinase-2/tissue inhibitor of metalloproteinase-2 MMP2/TIMP-2. METHODS: The present study used a sample of 36 children and adolescents subdivided into two groups: I - 20 children with MCNS, subjected to examination twice: A - in relapse of nephrotic syndrome, before treatment and B - after regression of proteinuria; II - 16 children with FSGS. MMPs and TIMPs and NGAL levels were measured in the urine using ELISA kit. MMP-9/TIMP-1, MMP-2/TIMP-2 and MMP-9/NGAL ratios were calculated. RESULTS: Median NGAL/cr. was significantly higher in MCNS and FSGS patients when compared to healthy controls. Both, NGAL and MMP-9 urinary levels were significantly elevated in FSGS subjects, as compared with control subjects. Contrary to FSGS children, in MCNS group, before treatment only NGAL/cr., but not MMP-9/cr. was increased. Urinary concentrations of NGAL and MMP-9 were highly associated with each other (NGAL/cr. vs. MMP-9/cr., r=0.485, p<0.01). Median urine MMP-9/NGAL ratio in FSGS patients was significantly higher than in patients with MCNS. We also found that significant increase in MMP-9/NGAL was associated with FSGS [odds ratio (OR) - 9.0; confidence interval (CI) 1.97-41.07].CONCLUSION: MMP-9/NGAL ratio may serve as differentiation marker between MCNS and FSGS in nephrotic children.

Concepts: Kidney, Nephrotic syndrome, Normal distribution, Matrix metalloproteinase, Proteinuria, Minimal change disease, Focal segmental glomerulosclerosis, Glomerulosclerosis

27

BACKGROUND: Nephrotic syndrome (NS) is a recognized complication of immune tolerance induction (ITI) therapy, a treatment strategy used to treat inhibitors in patients with hemophilia B receiving factor IX concentrate. CASE DIAGNOSIS/TREATMENT: We present a 4-year-old boy with hemophilia B and an inhibitor who underwent ITI, and developed NS 19 months into this therapy. A percutaneous renal biopsy was safely performed with factor IX (FIX) concentrate administration both preceding and following the procedure. The patient’s inhibitor level had increased to 1.4-1.6 Bethesda Units just prior to the onset of proteinuria. Histology confirmed segmental membranous nephropathy (MGN). The patient was continued on FIX concentrate as ITI and also received 4 weekly doses of rituximab and ongoing immunosuppression with mycophenolate mofetil. This resulted in the complete resolution of his inhibitor and his NS. He continues with a modified ITI regimen and remains inhibitor-free without proteinuria >12 months post-biopsy. CONCLUSIONS: Hemophilia B patients undergoing ITI should be regularly screened for NS. At first detection of proteinuria, with proper precautions, a percutaneous kidney biopsy can be performed safely in patients with low levels of inhibitor. Our patient had segmental MGN with complete remission of NS.

Concepts: Kidney, Patient, Nephrotic syndrome, Proteinuria, Haemophilia B, Mycophenolic acid, Mycophenolate mofetil, Nephritic syndrome

27

Aim: Children with steroidresistant (SR) and steroid-dependent (SD) nephrotic syndrome (NS) pose a treatment challenge. Literature on the use of tacrolimus (TAC), a calcineurin inhibitor, for maintenance treatment of NS is sparse. We aimed to evaluate the efficacy and safety of low-dose, long-term TAC for inducing and sustaining remission in children with SD/SR NS. Methods: Data from patients treated at our center from 1999 to 2009 were analyzed. Results: 40 patients with NS were treated with TAC for 3 - 80-month periods (median 25.2 months). Diagnoses included focal segmental glomerulosclerosis (FSGS) (60%), IgM nephropathy (15%), minimal change disease (20%) and membrano-proliferative glomerulonephritis (MPGN) (5%). 58% of patients had been previously treated with alternate agents. After 1, 2, and 3 years on TAC, complete remission was achieved in 26%, 48%, and 29% of patients; complete or partial remission was achieved in 85%, 100%, and 86%, respectively (p < 0.05). Median time to remission was 41 days (range: 10 - 270 days). FSGS and SR diseases were associated with lower likelihood of remission (p < 0.05). Remission was equally likely in both treatment naïve patients and those who had received prior second-line agents. Conclusion: Our results demonstrate that TAC treatment for children with SR/SD NS is associated with high rates of sustained remission, even when prior second-line agents failed.

Concepts: Kidney, Nephrotic syndrome, Proteinuria, Kidney diseases, Minimal change disease, Focal segmental glomerulosclerosis, Glomerulosclerosis, Sustain

27

Immunoglobulin M (IgM) nephropathy is an idiopathic glomerulonephritis characterized by mesangial deposits of IgM. IgM nephropathy presenting with proteinuria, especially nephrotic syndrome, frequently is steroid-dependent or steroidresistant and associated with reaching endstage renal disease after a 15-year follow-up. Because no long-term effective treatment is known for patients with IgM nephropathy, there is a clear need for therapeutic alternatives. We describe a patient with IgM nephropathy represented by recurrence of nephrotic syndrome who achieved longterm remission with interferon-α sustained treatment.

Concepts: Immune system, Kidney, Nephrotic syndrome, Glomerulonephritis, Proteinuria, Nephritic syndrome, Minimal change disease, IgA nephropathy

27

BACKGROUND: Glomerular podocyte molecules are involved in the pathogenesis of congenital nephrotic syndrome. However, their role in primary nephrotic syndrome is not clear. This study investigated the expression of nephrin, podocin and synaptopodin in primary nephrotic syndrome. METHODS: Eighty-seven patients with primary nephrotic syndrome including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN) and membranoproliferative glomerulonephritis Type I (MPGN) were included in the study. Glomerular expression of nephrin, podocin and synaptopodin was studied in renal biopsies by immunofluorescence and immunohistochemistry. Correlation of expression with clinical and biochemical parameters was performed. RESULTS: The pattern of expression for all podocyte proteins in controls was uniform fine granular along the capillary walls towards the visceral epithelial cell aspect. Glomerular expression of nephrin was present in all renal biopsies and was similar to that in controls. Glomerular synaptopodin expression was seen in all MN and MPGN patients, while it was seen in 74 % (17/23) MCD and 93.5 % (29/31) FSGS. Reduced synaptopodin expression showed no correlation with clinical and biochemical factors. Podocin expression was present in 5/23 MCD (22 %), 3/31 FSGS (9.6 %), 13/17 MN (76.4 %) and 13/16 MPGN (81 %) patients. The reduced expression of podocin significantly correlated with the degree of proteinuria (p = 0.032). No correlation with age, gender and serum creatinine level was observed. CONCLUSION: Reduction of glomerular podocin expression found in MCD and FSGS is related to the amount of proteinuria. Our findings suggest that alteration in podocyte phenotype may not be a primary event and may reflect the degree of podocyte injury in primary nephrotic syndrome.

Concepts: Kidney, Nephrotic syndrome, Proteinuria, Kidney diseases, Minimal change disease, Focal segmental glomerulosclerosis, Membranous glomerulonephritis, Membranoproliferative glomerulonephritis

19

Repository corticotropin injection (RCI; H.P. Acthar(®) Gel; Mallinckrodt Pharmaceuticals Inc., Hampton, NJ) is a highly purified, prolonged-release porcine preparation of adrenocorticotropic hormone (ACTH) analogue that is FDA-approved for treatment of 19 autoimmune and inflammatory disorders. The diverse physiological actions of RCI at the melanocortin receptors (MCRs) affect processes involved in inflammation, pigmentation, steroidogenesis, and immunomodulation. Although RCI has been approved to treat inflammatory and autoimmune diseases for more than 60 years, recent progress in understanding both MCRs and the effects of RCI in modulating immune responses has led to increased interest in RCI as a therapeutic choice. The objective of this narrative literature review is to summarize key clinical and economic data on RCI treatment of seven disorders: infantile spasms (IS), multiple sclerosis (MS) relapses, proteinuria in nephrotic syndrome, rheumatoid arthritis (RA), dermatomyositis/polymyositis (DM/PM), systemic lupus erythematosus (SLE), and symptomatic sarcoidosis based on published literature and product information. An extended report is available as the Academy of Managed Care Pharmacy (AMCP) Formulary dossier for H.P. Acthar(®) Gel.

Concepts: Rheumatoid arthritis, Rheumatology, Nephrotic syndrome, Corticosteroid, Systemic lupus erythematosus, Lupus erythematosus, Autoimmune diseases, Proteinuria