The diagnostic trash bin of focal and segmental glomerulosclerosis--an effort to provide rational clinical guidelines

Rituximab in adult minimal change disease and focal segmental glomerulosclerosis - What is known and what is still unknown?

Primary forms of minimal change disease and focal segmental glomerulosclerosis are rare podocytopathies and clinically characterized by nephrotic syndrome. Glucocorticoids are the cornerstone of the initial immunosuppressive treatment in these two entities. Especially among adults with minimal change disease or focal segmental glomerulosclerosis, relapses, steroid dependence or resistance are common and necessitate re-initiation of steroids and other immunosuppressants. Effective steroid-sparing therapies and introduction of less toxic immunosuppressive agents are urgently needed to reduce undesirable side effects, in particular for patients whose disease course is complex. Rituximab, a B cell depleting monoclonal antibody, is increasingly used off-label in these circumstances, despite a low level of evidence for adult patients. Hence, critical questions concerning drug-safety, long-term efficacy and the optimal regimen for rituximab-treatment remain unanswered. Evidence in the form of large, multicenter studies and randomized controlled trials are urgently needed to overcome these limitations.

Complete remission of nephrotic syndrome in an infant with focal segmental glomerulosclerosis: is it renin-angiotensin blockade?

Nephrotic syndrome presenting in the first year of life is often challenging, with substantial risk of progression to end-stage renal disease (ESRD). Focal segmental glomerulosclerosis (FSGS) comprises up to 20% of biopsy-proven glomerular disease in children and adults. We report on a 9-month-old infant who presented with nephrotic syndrome, hypertension and progressive deterioration of renal function due to FSGS. As immunosuppressive agents are often unsuccessful in treating this condition, we adopted renoprotection as the mainstay treatment for this patient, through rigorous control of blood pressure and proteinuria with a multi-drug regimen including renin-angiotensin axis blockade. Initially, there was partial improvement, with a gradual decline in proteinuria and a concomitant rise in the glomerular filtration rate, before the disease eventually passed into complete clinical and laboratory remission. We speculate that infants with steroid-resistant nephrotic syndrome due to FSGS may benefit from tight control of hypertension, mainly though early blockade of the renin-angiotensin axis. We believe that its renoprotecive mechanism counteracts the deleterious effects of both hypertension and proteinuria, thereby not only preventing progressive renal disease, but even paving the way for a remission, as in our patient. To the best of our knowledge, this is the first report of an infant with nephrotic syndrome (NS) due to FSGS that passed into complete remission while the patient was on renoprotective measures including the use of angiotensin-converting enzyme inhibitors (ACEis).

Podocyte foot process effacement as a diagnostic tool in focal segmental glomerulosclerosis

Podocyte foot process effacement is characteristic of proteinuric renal diseases. In minimal change nephrotic syndrome (MCNS) foot processes are diffusely effaced whereas the extent of effacement varies in focal segmental glomerulosclerosis (FSGS). Here we measured foot process effacement in FSGS and compared it to that in MCNS and in normal kidneys. A clinical diagnosis was used to differentiate idiopathic FSGS from secondary FSGS. Median foot process width, determined morphometrically by electron microscopy, was 3236 nm in 17 patients with idiopathic FSGS, 1098 nm in 7 patients with secondary FSGS, and 1725 nm in 15 patients with MCNS, as compared to 562 nm in 12 control patients. Multivariate analysis showed that foot process width did not correlate with proteinuria or serum albumin levels but was significantly associated as an independent factor with the type of disease. Foot process width over 1500 nm differentiated idiopathic from secondary FSGS with high sensitivity and specificity. Our results show that quantitative analysis of foot processes may offer a potential tool to distinguish idiopathic from secondary FSGS.