Glucocorticoids in the treatment of patients with primary focal segmental glomerulosclerosis and moderate proteinuria

Glucocorticoid- and pioglitazone-induced proteinuria reduction in experimental NS both correlate with glomerular ECM modulation

Idiopathic nephrotic syndrome (NS) is a common glomerular disease. Although glucocorticoids (GC) are the primary treatment, the PPARγ agonist pioglitazone (Pio) also reduces proteinuria in patients with NS and directly protects podocytes from injury. Because both drugs reduce proteinuria, we hypothesized these effects result from overlapping transcriptional patterns. Systems biology approaches compared glomerular transcriptomes from rats with PAN-induced NS treated with GC vs. Pio and identified 29 commonly regulated genes-of-interest, primarily involved in extracellular matrix (ECM) remodeling. Correlation with clinical idiopathic NS patient datasets confirmed glomerular ECM dysregulation as a potential mechanism of injury. Cellular deconvolution in silico revealed GC- and Pio-induced amelioration of altered genes primarily within podocytes and mesangial cells. While validation studies are indicated, these analyses identified molecular pathways involved in the early stages of NS (prior to scarring), suggesting that targeting glomerular ECM dysregulation may enable a future non-immunosuppressive approach for proteinuria reduction in idiopathic NS.

Rituximab in the treatment of primary FSGS: time for its use in routine clinical practice?

Focal segmental glomerulosclerosis (FSGS) is a common cause of nephrotic syndrome and whilst advances have been made in the pathophysiology, diagnostics and management of other podocytopathies, primary FSGS remains the most elusive. It has been assumed for a long time that a circulatory permeability factor exists that mediates podocyte injury, and the potential for autoantibody-mediated disease therefore raises the question as to whether patients may benefit from targeted B-cell therapy with rituximab. The prospective case series of seven patients by Roccatello et al. adds to the limited but growing evidence suggesting that B-cell depletion therapy can be safe and effective in the treatment of primary FSGS. In this editorial we explore the available evidence that suggests how and in whom rituximab may play a role in the management of primary FSGS, as well as the limitations and other potential future treatments. Further research and randomized controlled trials are needed to include larger numbers of patients, feature genetic screening and incorporate data on B-cell kinetics as a potential guide for dosing and frequency of rituximab.

Efficacy and Safety of Immunosuppressive Therapy in Primary Focal Segmental Glomerulosclerosis: A Systematic Review and Meta-analysis

Rationale & Objective

Focal segmental glomerulosclerosis (FSGS) is a rare condition that can lead to kidney function decline and chronic kidney failure. Immunosuppressants are used to treat primary FSGS. However, their efficacy and safety in FSGS are not clearly established. We assessed current knowledge on clinical effectiveness and safety of immunosuppressants for primary FSGS.

Study Design

Systematic review of randomized controlled trials, interventional nonrandomized controlled trials, observational studies, retrospective studies, and registries.

Setting & Participants

Patients with primary and genetic FSGS.

Selection Criteria for Studies

Medline, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for English-language, primary-FSGS studies from inception to 2019. Clinical outcomes were changes from baseline in proteinuria, kidney function, and kidney survival.

Data Extraction

2 investigators independently screened studies and extracted data.

Analytical Approach

Study results were summarized using random-effects models either as ratios of means between follow-up and baseline measurements or as HRs.

Results

We included 98 articles. Substantial heterogeneity was observed in patient baseline characteristics and study designs. Most studies assessed treatment with corticosteroids alone or combined with other drugs, mainly immunosuppressants. Patients treated with immunosuppressants showed reduced proteinuria (14 studies; ratio of means, 0.36; 95% CI, 0.20-0.47), decreased creatinine clearance (mean difference, −25.03; 95% CI, −59.33 to −9.27) and (significantly) lower estimated glomerular filtration rates (mean difference, −7.61 mL/min/1.73 m²; 95% CI, −14.98 to 0.25 mL/min/1.73 m²). Immunosuppressant therapy had an uncertain effect on reducing the chronic kidney failure risk. Hypertension and infections were the most commonly reported adverse events.

Limitations

Heterogeneity in study designs, patient populations, and treatment regimens; no access to individual patient–level data.

Conclusions

This systematic review supports proteinuria reduction with immunosuppressant therapy in primary FSGS over varying follow-up periods. The effects of immunosuppressants on kidney survival remain uncertain. This review underscores the need for better-designed and adequately controlled studies to assess immunosuppressant therapy in patients with primary FSGS.

Efficacy and Safety of ACE Inhibitor and Angiotensin Receptor Blocker Therapies in Primary Focal Segmental Glomerulosclerosis Treatment: A Systematic Review and Meta-analysis

Rationale and Objective

Angiotensin-converting enzyme inhibitor or angiotensin receptor blocker therapy (renin-angiotensin-aldosterone system [RAAS] inhibitor) to control proteinuria in primary and genetic focal segmental glomerulosclerosis (FSGS) follows guidelines based on other proteinuria-related kidney diseases. There is no consensus on the efficacy and safety of RAAS inhibitor therapies in primary and genetic FSGS. This systematic review assessed the effects of RAAS inhibitor therapy on kidney outcomes in these patients.

Study Design

Systematic review of randomized controlled trials, interventional nonrandomized studies, observational studies, and retrospective studies.

Setting & Study Populations

Patients with primary and genetic FSGS.

Selection Criteria for Studies

PubMed, Cochrane Library, and Embase.

Data Extraction

2 investigators independently screened studies and extracted data.

Analytical Approach

Results were summarized as the ratio of means (ROM) between baseline and follow-up measurements or as the hazard ratio using random-effects models.

Results

30 publications were selected; 5 were controlled trials (4 randomized controlled trials). 8 assessed RAAS inhibitor monotherapy, while the rest studied RAAS inhibitors in combination with other drugs, mainly immunosuppressants. On average, a 32% proteinuria reduction (ROM, 0.68; 95% CI, 0.47-0.98) and no change in creatinine clearance (ROM, 0.95; 95% CI, 0.77-1.16) from baseline to the last reported follow-up was observed in patients treated with RAAS inhibitor monotherapy. When a RAAS inhibitor was combined with other drugs, a 72% proteinuria reduction was observed from baseline to the last reported follow-up (ROM, 0.24; 95% CI, 0.08-0.75). The published data did not allow for the assessment of the effects of RAAS inhibitor monotherapy on estimated glomerular filtration rate and end-stage kidney disease risks.

Limitations

Large study heterogeneity in design, patient populations, and treatment regimens. No access to individual patient-level data.

Conclusions

This review supports the tendency to observe a proteinuria reduction with RAAS inhibitors in patients with primary FSGS. RAAS inhibitor monotherapy was associated with maintained kidney function, as shown by no change in creatinine clearance. Strong evidence to quantify the effects of RAAS inhibitor monotherapy on end-stage kidney disease and glomerular filtration rate was lacking. Larger, well-designed clinical trials are needed to better understand the effects of RAAS inhibitors on primary FSGS.