Therapy of relapsing minimal-change disease in adults: a new approach?

CD80 Insights as Therapeutic Target in the Current and Future Treatment Options of Frequent-Relapse Minimal Change Disease

Minimal change disease (MCD) is the most common cause of idiopathic nephrotic syndrome in children, and it is well known for its multifactorial causes which are the manifestation of the disease. Proteinuria is an early consequence of podocyte injury and a typical sign of kidney disease. Steroid-sensitive patients react well with glucocorticoids, but there is a high chance of multiple relapses. CD80, also known as B7-1, is generally expressed on antigen-presenting cells (APCs) in steroid-sensitive MCD patients. Various glomerular disease models associated with proteinuria demonstrated that the detection of CD80 with the increase of urinary CD80 was strongly associated closely with frequent-relapse MCD patients. The role of CD80 in MCD became controversial because one contradicts finding. This review covers the treatment alternatives for MCD with the insight of CD80 as a potential therapeutic target. The promising effectiveness of CD20 (rituximab) antibody and CD80 inhibitor (abatacept) encourages further investigation of CD80 as a therapeutic target in frequent-relapse MCD patients. Therapeutic-based antibody towards CD80 (galiximab) had never been investigated in MCD or any kidney-related disease; hence, the role of CD80 is still undetermined. A new therapeutic approach towards MCD is essential to provide broader effective treatment options besides the general immunosuppressive agents with gruesome adverse effects.

Case Report: Novel Dietary Supplementation Associated With Kidney Recovery and Reduction in Proteinuria in a Dialysis Dependent Patient Secondary to Steroid Resistant Minimal Change Disease

Minimal change disease (MCD) is the most common cause of nephrotic syndrome worldwide. For decades, the foundation of the treatment has been corticosteroids. However, relapse rate is high and up to 40% of patients develop frequent relapsing/steroid dependent course and one third become steroid resistant. This requires treatment with repeated courses of corticosteroids, and second and third line immunomodulators increasing the incidence of drug related adverse effects. More recently, there have been reports of a very small subset of Nephrotic Syndrome (NS) patients who are initially steroid sensitive and later become secondarily steroid resistant. The disease course in this small subset is often protracted leading ultimately to end stage kidney disease requiring dialysis or kidney transplantation. Unfortunately, patients with this disease course do not do well post transplantation because 80% of them will develop disease recurrence that will ultimately lead to graft failure. Few approaches have been tried over many years to reduce the frequency of relapses, and steroid dependence and there is absolutely no therapeutic intervention for patients who develop secondary steroid resistance. Nonetheless, their therapeutic index is low, evidencing the need of a safer complementary treatment. Several hypotheses, including an oxidative stress-mediated mechanism, and immune dysregulation have been proposed to date to explain the underlying mechanism of Minimal Change Disease (MCD) but its specific etiology remains elusive. Here, we report a case of a 54-year-old man with steroid and cyclosporine resistant MCD. The patient rapidly progressed to end stage kidney disease requiring initiation of chronic dialysis. Intradialytic parenteral nutrition (IDPN), albumin infusion along with a proprietary dietary supplement, as part of the supportive therapy, led to kidney function recovery and complete remission of MCD without relapses.

Podocytopathies

Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.

The Evolving Role of Rituximab in Adult Minimal Change Glomerulopathy

BACKGROUND

Minimal-change glomerulopathy is defined histologically by the presence of normal glomeruli on light microscopy and diffuse podocyte effacement on electron microscopy. Although effective in children, corticosteroid treatment in adults is more variable and time to response can be prolonged. Data to support rituximab use in adults with corticosteroid-dependent or resistant minimal-change glomerulopathy are limited. Here, we describe the clinical course of adults with corticosteroid-dependent or -resistant minimal-change glomerulopathy who received rituximab.

METHODS

Demographic and clinical data were collected and analyzed from all adult patients with native kidney, biopsy-proven, minimal-change glomerulopathy who were administered rituximab between 2009 and 2014 and cared for at the UNC Kidney Center.

RESULTS

Ten patients with corticosteroid-resistant (n = 5) or corticosteroid-dependent (n = 5) idiopathic minimal-change glomerulopathy were treated with rituximab between 2009 and 2014. Rituximab treatment induced remission in all 10 patients with a median time to remission of 2 months. The median time from rituximab to corticosteroid discontinuation was 3.5 months. The median remission time was 29 months and follow-up time was 39.5 months. No serious adverse events attributable to rituximab were observed.

CONCLUSION

Rituximab induced remission in all patients with corticosteroid-dependent or -resistant minimal-change glomerulopathy, and may hold great therapeutic potential with good efficacy and minimal toxicity. Mounting evidence implies that a well-conducted randomized controlled clinical trial using rituximab in adults with minimal-change glomerulopathy in both corticosteroid-resistant and corticosteroid-dependent patients is warranted.

Rituximab use in adult primary glomerulopathy: where is the evidence?

Rituximab is a chimeric anti-CD20 antibody that results in depletion of B-cell lymphocytes. It is currently used in the treatment of a variety of autoimmune diseases, in addition to CD20-positive lymphomas. The use of rituximab in the treatment of the adult primary glomerular diseases has emerged recently, although not yet established as first-line therapy in international guidelines. In patients with steroid-dependent minimal change disease or frequently relapsing disease, and in patients with idiopathic membranous nephropathy (IMN), several retrospective and prospective studies support the use of rituximab to induce remission, whereas in idiopathic focal and segmental glomerulosclerosis (FSGS), the use of rituximab has resulted in variable results. Evidence is still lacking for the use of rituximab in patients with immunoglobulin A nephropathy (IgAN) and idiopathic membranoproliferative glomerulonephritis (MPGN), as only few reports used rituximab in these two entities. Randomized controlled trials (RCTs) are warranted and clearly needed to establish the definitive role of rituximab in the management of steroid-dependent and frequently relapsing minimal change disease, IMN, both as first-line and second-line treatment, and in MPGN. We await the results of an ongoing RCT of rituximab use in IgAN. Although current evidence for the use of rituximab in patients with idiopathic FSGS is poor, more RCTs are needed to clarify its role, if any, in the management of steroid-resistant or steroid-dependent FSGS.

Any value of podocyte B7-1 as a biomarker in human MCD and FSGS?

Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are the most common causes of nephrotic syndrome in children and in young adults. Relapsing MCD carries the risk of severe complications and prolonged immunosuppression, whereas FSGS remains largely untreatable and urgently needs more effective treatments. Recently, induction of B7-1 (CD80), an immune-related protein expressed by antigen-presenting cells, was observed in podocytes of MCD and FSGS patients, suggesting that B7-1 plays a role in the pathogenesis of these diseases, and hence that abatacept, a B7-1 inhibitor, could be a possible treatment. Since previous studies raised serious concerns regarding the reliability of immunohistochemical assays for B7-1 detection and the efficacy of B7-1 inhibitory treatment, we investigated B7-1 podocyte expression in MCD and FSGS patients. Using different primary antibodies and immunohistochemical assays, no significant upregulation of podocyte B7-1 was detected in patients' biopsies compared with controls. To further confirm our findings, we analyzed mice with adriamycin-induced nephropathy, a model of human FSGS, and mice injected with LPS as additional control. Podocyte B7-1 was not observed in mice injected with adriamycin or LPS either. In conclusion, since B7-1 is not induced in podocyte of MCD and FSGS patients, the antiproteinuric action of abatacept, if confirmed, may not be the result of an effect on podocyte B7-1.

A higher frequency of CD4⁺CXCR5⁺ T follicular helper cells in adult patients with minimal change disease

Background. T follicular helper (TFH) cells are involved in the humoral immune responses. This study is aimed at examining the frequencies of different subsets of CD4⁺CXCR5⁺ TFH cells in adult patients with minimal change disease (MCD). Methods. A total of 27 patients and 14 healthy controls (HC) were characterized for the levels of sera cytokines, inducible T-cell costimulator (ICOS), and programmed death 1 (PD-1) of positive TFH cells by flow cytometry. The level of sera IL-21 was examined; 24 h urinary protein and eGFR were calculated. The potential correlation between the frequency of different subsets of TFH cells and the values of clinical measures in MCD patients were analyzed. Results. The frequency of circulating CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺, and CD4⁺CXCR5⁺PD-1⁺ TFH cells and the levels of sera IL-17A, IFN-γ, IL-2, IL-10, IL-4, and IL-21 were significantly higher in MCD patients (P < 0.05) than that in the HC group. Furthermore, the percentages of circulating CD4⁺CXCR5⁺ TFH cells were negatively correlated with the values of eGFR (r = −0.4849, P < 0.05) and the percentages of CD4⁺CXCR5⁺PD-1⁺ TFH cells were correlated positively with the levels of serum IL-21 (r = 0.6137, P < 0.05) and 24 h urinary protein (r = 0.1410, P < 0.05) in those patients. Also, the percentages of CD4⁺CXCR5⁺ICOS⁺ TFH cells were correlated positively with the levels of serum IL-21 (r = 0.6201, P < 0.05) and 24 h urinary protein (r = 0.7519, P < 0.05). Following standard therapies, the percentages of circulating CD4⁺CXCR5⁺, CD4⁺CXCR5⁺PD-1⁺, and CD4⁺CXCR5⁺ICOS⁺ TFH cells and the levels of serum IL-21 were significantly reduced, but the levels of serum IL-4 and IL-10 were increased (P < 0.05). Conclusions. A higher frequency of CD4⁺CXCR5⁺ TFH cells that existed in adult patients with MCD could be new target for intervention of MCD.