Th17/Treg imbalance in adult patients with minimal change nephrotic syndrome

Exosomes secreted by podocytes regulate the differentiation of Th17/Treg cells in idiopathic nephrotic syndrome

Background

Previous studies have demonstrated that immune cells release exosomes, which act as antigen-presenting vesicles to activate T cells. In our previous study, we discovered that podocytes, a type of kidney cell, can also exhibit antigen-presenting functions to naïve CD4+ T cells in idiopathic nephrotic syndrome (INS). Building upon these findings, the objective of this study was to investigate whether podocytes can regulate the balance between Th17 and Treg cells through the release of exosomes.

Methods

We co-cultured naïve CD4+ T cells with LPS-treated bone marrow dendritic cells (LPS-BMDC), LPS-treated mouse podocyte clone 5 (LPS-MPC-5), and exosomes derived from LPS-MPC-5 (LPS-EXO). As a control group, naïve CD4+ T cells were cultured with exosomes from untreated MPC-5 (EXO). After 48 h, we analyzed the percentages of Th17 and Treg cells using flow cytometry, measured the concentrations of IL-17A, IL-10, and IL-4 were using ELISA, and examined the expressions of IL-17a, IL-10, RORC, and FOXP3 using RT-qPCR.

Results

We confirmed the presence of exosomes derived from podocytes based on their morphology, size distribution, concentrations, and the levels of exosomes-specific markers. The percentage of Th17 and Treg cells in the LPS-EXO group was significantly higher than that in the control groups, but lower than in the LPS-MPC-5 group. Furthermore, the ratio of Th17/Treg was relatively higher in the LPS-EXO group compared to the LPS-MPC-5 group.

Conclusion

This study indicated further insights into the role of exosomes released from LPS-treated podocytes in regulating the balance between Th17 and Treg cells in INS.

The efficacy and safety of rituximab with or without glucocorticoid in inducing remission of MCD with different clinical presentations in adults: a retrospective study

Background

To investigate the efficacy and safety of rituximab (RTX) with or without glucocorticoid (GC) in inducing remission of minimal change disease (MCD) in adults.

Methods

Twenty-one adult MCD patients were included in the study. The patients were assigned to the following three groups according to their background before RTX treatment: an RTX single drug direct induction treatment group (Group A; n = 9), a short-term, low-dose GC combined with RTX induction treatment group (Group B; n = 4), and a short-term, adequate-dose GC-induced remission and RTX maintenance treatment group (Group C; n = 8). The primary endpoints were the time to induction of remission and the rate of clinical remission at 12 months.

Results

All patients achieved clinical remission, with 19 (90.48%) achieving complete remission (CR), and the median remission time was 4 (2.5, 12) weeks. Eight (88.89%) patients in Group A achieved CR, and the median remission time was 3 (2.25, 14) weeks. In Group B, three (75.00%) patients achieved CR, with a median remission time of 4 (4, 10) weeks. In Group C, eight (100.00%) patients achieved CR, and the median remission time was 3.5 (2, 4) weeks.

Conclusions

In MCD patients without acute kidney injury, adequate RTX alone or short-term combined treatment with low-dose GCs can effectively induce and maintain MCD remission. Adequate short-term GCs combined with RTX maintenance may be an effective alternative for MCD patients in context of acute kidney injury. There is a need to investigate different induction therapy regimens for the remission of MCD patients with different backgrounds.

A prediction model for prognosis of nephrotic syndrome with tuberculosis in intensive care unit patients: a nomogram based on the MIMIC-IV v2.2 database

Background

Currently, a scarcity of prognostic research exists that concentrates on patients with nephrotic syndrome (NS) who also have tuberculosis. The purpose of this study was to assess the in-hospital mortality status of NS patients with tuberculosis, identify crucial risk factors, and create a sturdy prognostic prediction model that can improve disease evaluation and guide clinical decision-making.

Methods

We utilized the Medical Information Mart for Intensive Care IV version 2.2 (MIMIC-IV v2.2) database to include 1,063 patients with NS complicated by TB infection. Confounding factors included demographics, vital signs, laboratory indicators, and comorbidities. The Least Absolute Shrinkage and Selection Operator (LASSO) regression and the diagnostic experiment the receiver operating characteristic (ROC) curve analyses were used to select determinant variables. A nomogram was established by using a logistic regression model. The performance of the nomogram was tested and validated using the concordance index (C-index) of the ROC curve, calibration curves, internal cross-validation, and clinical decision curve analysis.

Results

The cumulative in-hospital mortality rate for patients with NS and TB was 18.7%. A nomogram was created to predict in-hospital mortality, utilizing Alb, Bun, INR, HR, Abp, Resp., Glu, CVD, Sepsis-3, and AKI stage 7 days. The area under the curve of the receiver operating characteristic evaluation was 0.847 (0.812-0.881), with a calibration curve slope of 1.00 (0.83-1.17) and a mean absolute error of 0.013. The cross-validated C-index was 0.860. The decision curves indicated that the patients benefited from this model when the risk threshold was 0.1 and 0.81.

Conclusion

Our clinical prediction model nomogram demonstrated a good predictive ability for in-hospital mortality among patients with NS combined with TB. Therefore, it can aid clinicians in assessing the condition, judging prognosis, and making clinical decisions for such patients.

A novel flow cytometry panel to identify prognostic markers for steroid-sensitive forms of idiopathic nephrotic syndrome in childhood

Introduction

The clinical evolution of steroid-sensitive forms of pediatric idiopathic nephrotic syndrome (INS) is highly heterogeneous following the standard treatment with prednisone. To date, no prognostic marker has been identified to predict the severity of the disease course starting from the first episode.

Methods

In this monocentric prospective cohort study we set up a reproducible and standardized flow cytometry panel using two sample tubes (one for B-cell and one for T-cell subsets) to extensively characterized the lymphocyte repertoire of INS pediatric patients. A total of 44 children with INS at disease onset were enrolled, sampled before and 3 months after standard induction therapy with prednisone and followed for 12 months to correctly classify their disease based on relapses. Age-matched controls with non immune-mediated renal diseases or with urological disorders were also enrolled. Demographical, clinical, laboratory and immunosuppressive treatment data were registered.

Results

We found that children with INS at disease onset had significantly higher circulating levels of total CD19+ and specific B-cell subsets (transitional, mature-naïve, plasmablasts/plasmacells, CD19+CD27+, unswitched, switched and atypical memory B cells) and reduced circulating levels of Tregs, when compared to age-matched controls. Prednisone therapy restored most B- and T-cell alterations. When patients were subdivided based on disease relapse, relapsing patients had significantly more transitional, CD19+CD27+ memory and in particular unswitched memory B cells at disease onset, which were predictive of a higher risk of relapse in steroid-sensitive patients by logistic regression analysis, irrespective of age. In accordance, B-cell dysregulations resulted mainly associated with steroid-dependence when patients were stratified in different disease severity forms. Of note, Treg levels were reduced independently from the disease subgroup and were not completely normalized by prednisone treatment.

Conclusion

We have set up a novel, reproducible, disease-specific flow cytometry panel that allows a comprehensive characterization of circulating lymphocytes. We found that, at disease onset, relapsing patients had significantly more transitional, CD19+CD27+ memory and unswitched memory B cells and those who are at higher risk of relapse had increased circulating levels of unswitched memory B cells, independently of age. This approach can allow prediction of clinical evolution, monitoring of immunosuppression and tailored treatment in different forms of INS.

Scaffold protein SH3BP2 signalosome is pivotal for immune activation in nephrotic syndrome

Despite clinical use of immunosuppressive agents, the immunopathogenesis of minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) remains unclear. Src homology 3-binding protein 2 (SH3BP2), a scaffold protein, forms an immune signaling complex (signalosome) with 17 other proteins, including phospholipase Cγ2 (PLCγ2) and Rho-guanine nucleotide exchange factor VAV2 (VAV2). Bioinformatic analysis of human glomerular transcriptome (Nephrotic Syndrome Study Network cohort) revealed upregulated SH3BP2 in MCD and FSGS. The SH3BP2 signalosome score and downstream MyD88, TRIF, and NFATc1 were significantly upregulated in MCD and FSGS. Immune pathway activation scores for Toll-like receptors, cytokine-cytokine receptor, and NOD-like receptors were increased in FSGS. Lower SH3BP2 signalosome score was associated with MCD, higher estimated glomerular filtration rate, and remission. Further work using Sh3bp2KI/KI transgenic mice with a gain-in-function mutation showed ~6-fold and ~25-fold increases in albuminuria at 4 and 12 weeks, respectively. Decreased serum albumin and unchanged serum creatinine were observed at 12 weeks. Sh3bp2KI/KI kidney morphology appeared normal except for increased mesangial cellularity and patchy foot process fusion without electron-dense deposits. SH3BP2 co-immunoprecipitated with PLCγ2 and VAV2 in human podocytes, underscoring the importance of SH3BP2 in immune activation. SH3BP2 and its binding partners may determine the immune activation pathways resulting in podocyte injury leading to loss of the glomerular filtration barrier.

Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis

The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.

The kinetics of mTORC1 activation associates with FOXP3 expression pattern of CD4+ T cells and outcome of steroid-sensitive minimal change disease

Minimal change disease (MCD) usually responds to glucocorticoids (GCs) but relapses in most cases. Relapse pathogenesis after complete remission (CR) remains unclear. We hypothesized that FOXP3+ T regulatory cell (Treg) dysregulation may drive early relapses (ER). In this study, a cohort of 23 MCD patients were treated with a conventional GC regimen for the initial onset of nephrotic syndrome. Upon GC withdrawal, seven patients suffered from ER, while 16 patients sustained remission (SR) during the 12-month follow-up. Patients with ER had reduced FOXP3+ Treg proportions compared with healthy controls. Treg reduction, accompanied by IL-10 impairment, was ascribed to a proportional decline of FOXP3medium rather than FOXP3high cells. GC-induced CR was marked by a rise in the proportions of FOXP3+ and FOXP3medium cells compared to baseline levels. These increases declined in patients with ER. The expression level of phosphorylated ribosomal protein S6 was used to track the dynamic shifts in mTORC1 activity within CD4+ T cells of MCD patients at various stages of treatment. Baseline mTORC1 activity was inversely correlated with FOXP3+ and FOXP3medium Treg proportion. The mTORC1 activity in CD4+ T cells served as a reliable indicator for ER and demonstrated improved performance when paired with FOXP3 expression. Mechanically, targeting mTORC1 intervention by siRNAs sufficiently altered the conversion pattern of CD4+ T cell to FOXP3+ Treg. Taken together, the activity of mTORC1 in CD4+ T cells can act as a credible predictor for ER in MCD, especially when combined with FOXP3 expression, and may offer a potential therapeutic avenue for the treatment of podocytopathies.

Proteomics of Plasma and Plasma-Treated Podocytes: Application to Focal and Segmental Glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syndrome (INS), a glomerulopathy of presumably immune origin that is attributed to extrarenal pathogenic circulating factors. The recurrence of FSGS (rFSGS) after transplant occurs in 30% to 50% of cases. The direct analysis of patient plasma proteome has scarcely been addressed to date, mainly due to the methodological difficulties associated with plasma complexity and dynamic range. In this study, first, we compared different methods of plasma preparation, second, we compared the plasma proteomes of rFSGS and controls using two preparation methods, and third, we analyzed the early proximal signaling events in podocytes subjected to patient plasma, through a combination of phosphoproteomics and lipid-raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma proteins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n = 4). In both the soluble- and the EV-protein sets from the rFSGS patients, we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid-binding proteins, generally associated with lipoproteins, was found to be decreased in the soluble set from the rFSGS patients. In addition, three amino acid transporters involved in mTORC1 activation were found to be significantly increased in the EV from the rFSGS. Next, we incubated human podocytes for 30 min with 10% plasma from both groups of patients. The phosphoproteomics and raftomics of the podocytes revealed profound differences in the proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes highlight some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating-factor activity in podocytes.

State of the art in childhood nephrotic syndrome: concrete discoveries and unmet needs

Nephrotic syndrome (NS) is a clinical entity characterized by proteinuria, hypoalbuminemia, and peripheral edema. NS affects about 2-7 per 100,000 children aged below 18 years old yearly and is classified, based on the response to drugs, into steroid sensitive (SSNS), steroid dependent, (SDNS), multidrug dependent (MDNS), and multidrug resistant (MRNS). Forms of NS that are more difficult to treat are associated with a worse outcome with respect to renal function. In particular, MRNS commonly progresses to end stage renal failure requiring renal transplantation, with recurrence of the original disease in half of the cases. Histological presentations of NS may vary from minimal glomerular lesions (MCD) to focal segmental glomerulosclerosis (FSGS) and, of relevance, the histological patterns do not correlate with the response to treatments. Moreover, around half of MRNS cases are secondary to causative pathogenic variants in genes involved in maintaining the glomerular structure. The pathogenesis of NS is still poorly understood and therapeutic approaches are mostly based on clinical experience. Understanding of pathogenetic mechanisms of NS is one of the 'unmet needs' in nephrology and represents a significant challenge for the scientific community. The scope of the present review includes exploring relevant findings, identifying unmet needs, and reviewing therapeutic developments that characterize NS in the last decades. The main aim is to provide a basis for new perspectives and mechanistic studies in NS.

Immunophenotypic Alterations in Adult Patients with Steroid-Dependent and Frequently Relapsing Nephrotic Syndrome

Immune dysregulation plays a key role in the pathogenesis of steroid-dependent/frequently relapsing nephrotic syndrome (SDNS/FRNS). However, in contrast with evidence from the pediatric series, no major B- or T-cell alterations have been described for adults. In these patients, treatment with rituximab allows safe discontinuation of steroids, but long-term efficacy is variable, and some patients experience NS relapses after B cell reconstitution. In this study, we aimed to determine disease-associated changes in the B and T cell phenotype of adult patients with SDND/FRNS after steroid-induced remission. We also investigated whether any of these changes in immune cell subsets could discriminate between patients who developed NS relapses after steroid-sparing treatment with rituximab from those who did not. Lymphocyte subsets in SDNS/FRNS patients (n = 18) were compared to those from patients with steroid-resistant NS (SRNS, n = 7) and healthy volunteers (HV, n = 15). Before rituximab, SDND/FRNS patients showed increased frequencies of total and memory B cells, mainly with a CD38-negative phenotype. Within the T-cell compartment, significantly lower levels of FOXP3⁺ regulatory T cells (Tregs) were found, mostly due to a reduction in CD45RO⁺ memory Tregs compared to both SRNS and HV. The levels of CD45RO⁺ Tregs were significantly lower at baseline in patients who relapsed after rituximab (n = 9) compared to patients who did not (n = 9). In conclusion, patients with SDND/FRNS displayed expansion of memory B cells and reduced memory Tregs. Treg levels at baseline may help identify patients who will achieve sustained remission following rituximab infusion from those who will experience NS relapses.

Immunosuppressive Agent Options for Primary Nephrotic Syndrome: A Review of Network Meta-Analyses and Cost-Effectiveness Analysis

Therapeutic options with immunosuppressive agents for glomerular diseases have widened with refinements to the Kidney Disease Improving Global Outcomes (KDIGO) guidelines from 2012 to 2021. However, international guidelines do not necessarily match the reality in each country. Expensive therapies such as rituximab and calcineurin inhibitors are sometimes inaccessible to patients with refractory nephrotic syndrome due to cost or regulations. Under the Japanese medical insurance system, rituximab is accessible but still limited to steroid-dependent patients who developed idiopathic nephrotic syndrome in childhood. Based on international KDIGO guidelines and other national guidelines, possible applications of immunosuppressive agents for nephrotic syndrome are comprehensively examined in this review. While rituximab has become the mainstay of immunosuppressive therapy for nephrotic syndrome, clinical trials have indicated that options such as cyclophosphamide, calcineurin inhibitors, and mycophenolate mofetil would be preferable. Given the rising number of patients with nephrotic syndrome worldwide, KDIGO guidelines mention the need for further consideration of cost-effectiveness. If the new option of rituximab is to be the first choice in combination with steroids for nephrotic syndrome, its cost-effectiveness should also be verified. Among the few studies examining the cost-effectiveness of treatments for nephrotic syndrome, administration of rituximab to young adults has been shown to be cost-beneficial, at least in Japan. However, further large-scale studies involving multiple facilities are needed to verify such findings. Network meta-analyses have concluded that the efficacy of rituximab remains controversial and confirmation through high-quality studies of large cohorts is needed. To this end, the mechanisms of action underlying immunosuppressive agents, both old and new, need to be understood and experience must be accumulated to evaluate possible effects and side effects.

T-cell and B-cell repertoire diversity are selectively skewed in children with idiopathic nephrotic syndrome revealed by high-throughput sequencing

BACKGROUND

Clinical studies suggest that the dysfunction of T cells and B cells may play an essential role in the pathogenesis of idiopathic nephrotic syndrome (INS), but laboratory evidence is lacking. Therefore, this study explored T-cell receptor (TCR) and B-cell receptor (BCR) profiling in children with idiopathic nephrotic syndrome.

METHODS

High-throughput sequencing technology was used to profile the TCR and BCR repertoires in children with INS. Peripheral blood was collected from ten INS patients, including five vinculin autoantibody-positive patients and five vinculin autoantibody-negative patients, before and after treatment. TCR and BCR libraries were constructed by 5'-RACE and sequenced by a DNBSEQ-T7 sequencer, and sequence analyses were performed using ReSeqTools, FastP, MiXCR, and VDJtools.

RESULTS

The TRA (T-cell receptor α), TRG (T-cell receptor γ), and IGH (immunoglobulin heavy chain) repertoires of the INS group were occupied by highly abundant clonotypes, whereas small clonotypes occupied the healthy group, especially TRA. A significant increase in the Shannon-Weaver index was observed for the TRA and TRG repertoires after treatment in vinculin autoantibody-negative patients, but a significant increase in the IGH repertoire after treatment was observed in vinculin autoantibody-positive patients. The frequency of some V-J pairs was significantly enriched in steroid-sensitive nephrotic syndrome patients. The usage frequency of the V and J genes was skewed in patients, which seemed not related to immunosuppressive therapy. However, after effective treatment, dynamic changes in the size of the individual clonotype were observed.

CONCLUSION

T-cell and B-cell immunity contribute to the pathogenesis of different INSs. Video: (MP4 99,786 KB).

Peripheral blood lymphocyte subsets in children with nephrotic syndrome: a retrospective analysis

BACKGROUND

Nephrotic syndrome (NS) in children is widely believed to be associated with severe changes in the immune system. Based on lymphocyte subset analysis, we examined the pathogenesis of immune deficiencies in children with NS with varying steroid sensitivity.

METHODS

Our study utilized flow cytometry to retrospectively analyze the ratios of lymphocyte subsets in 204 children with nephrotic syndrome and 19 healthy children.

RESULTS

Compared with healthy children, the ratio of CD4 + /CD8 + in onset and remission was decreased in SRNS group (p < 0.05), and CD19 + B lymphocytes were increased in onset (p < 0.05). Compared with onset, the proportion of CD19 + B lymphocytes decreased in SRNS, while the proportion of CD19 + B lymphocytes increased in SDNS, p < (0.01). The ratio of CD8 + T/CD19 + B in onset in SDNS group was significantly higher than that in SSNS and SRNS groups (p < 0.01) and healthy control group (p < 0.05). Compared with onset, the ratio of CD8 + T/CD19 + B in SDNS group decreased significantly (p < 0.01), while the ratio of CD8 + T/CD19 + B in SRNS group increased significantly (p < 0.01). The proportion of CD56 + CD16 + NK cells was significantly reduced in children with INS (p < 0.01).

CONCLUSION

CD8 + T lymphocytes may be involved in the mechanism of lymphocyte subsets disorder during onset of SDNS, while CD19 + B lymphocytes may be involved in the mechanism of lymphocyte subsets disorder during relapse of SDNS. The CD8 + T/CD19 + B ratio may predict the degree of frequent recurrence. There is a certain degree of lymphoid subsets disorder in children with NS.

The Immune System and Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome often responds to immunosuppressive treatment. Nevertheless, this syndrome-and the drugs used to treat it-remain important causes of patient morbidity. Idiopathic nephrotic syndrome is usually caused by minimal change disease or FSGS, diseases that primarily affect the podocytes. In spite of decades of research, the underlying causes of both diseases remain incompletely understood. There is, however, a large body of observational and experimental data linking the immune system with both minimal change disease and FSGS, including associations with systemic infections and hematologic malignancies. Perhaps most compellingly, many different immunomodulatory drugs are effective for treating idiopathic nephrotic syndrome, including biologic agents that have well-defined immune targets. In fact, the unexpected efficacy of targeted therapeutic agents has provided important new insights into the pathogenesis of these diseases. Given the large number of drugs that are available to deplete or block specific cells and molecules within the immune system, a better understanding of the immunologic causes of idiopathic nephrotic syndrome may lead to better diagnostic and therapeutic approaches.

B cell phenotype, activity, and function in idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (INS) is the most frequent glomerular disease in childhood. However, its underlying etiology mechanism lacks thorough understanding. Previous studies have described INS as a T cell functional disorder resulting in increased plasma lymphocyte-derived permeability factors. In children with frequent relapses of nephrotic syndrome, the mechanism underlying the therapeutic efficacy of CD20 monoclonal antibodies in depleting B cells may provide additional evidence in exploring the critical role of B lymphocytes in INS pathogenesis. Previous studies have proposed that RTX bound to CD20 through antibody-dependent and complement-dependent cytotoxicity and led to lytic clearance of B cells. Additionally, RTX exerted an effect by blocking the interaction between B and T cells or regulating homeostasis and functions of T cell subsets. Recent studies on the development, differentiation, and activation of B-lymphocytes in glomerular diseases have suggested that the B-lymphocytes participate in the INS pathogenesis through interaction with T cells, secretion of antibodies, or production of cytokines. In this study, we aimed to provide a detailed description of the current knowledge on the development, differentiation, activity, functions, and related regulating factors of B cells involved in INS. Thus, further understanding of the immunopathogenesis of INS may offer some opportunities in precisely targeting B cells during therapeutic interventions. IMPACT: The topic "B cells play a role in glomerular disease" is a novel point, which is not completely described previously. We described interactions between T and B cells and immunoglobulin, IgG, IgM, IgE, etc. as well in glomerular disease. The research of regulatory factors associated with B cell's function, like BAFF, is a hot topic in other diseases; however, it is rare in glomerular disease.

Immunomodulatory effects of the Bifidobacterium longum BL-10 on lipopolysaccharide-induced intestinal mucosal immune injury

The intestine is the largest digestive and immune organ in the human body, with an intact intestinal mucosal barrier. Bifidobacterium longum is the specific gut commensals colonized in the human gut for boosting intestinal immunity to defend against intestinal mucosal immune injury. In the LPS-induced intestinal injury model, the Bifidobacterium longum BL-10 was suggested to boost the intestinal immune. Detailly, compared with the LPS-induced mice, the BL10 group significantly reduced intestine (jejunum, ileum, and colon) tissue injury, pro-inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-6, IL-17, IL-22, and IL-12) levels and myeloperoxidase activities. Moreover, the B. longum BL-10 significantly increased the number of immunocytes (CD4+ T cells, IgA plasma cells) and the expression of tight junction protein (Claudin1 and Occludin). B. longum BL-10 regulated the body's immune function by regulating the Th1/Th2 and Th17/Treg balance, which showed a greater impact on the Th1/Th2 balance. Moreover, the results also showed that B. longum BL-10 significantly down-regulated the intestinal protein expression of TLR4, p-IκB, and NF-κB p65. The B. longum BL-10 increased the relative abundance of the genera, including Lachnospiraceae_NK4A136_group and Clostridia_UCG-014, which were related to declining the levels of intestinal injury. Overall, these results indicated that the B. longum BL-10 had great functionality in reducing LPS-induced intestinal mucosal immune injury.

A critical role of the podocyte cytoskeleton in the pathogenesis of glomerular proteinuria and autoimmune podocytopathies

Selective glomerular filtration relies on the membrane separating the glomerular arterioles from the Bowman space. As a major component of the glomerular filtration barrier, podocytes form foot processes by the actin cytoskeleton, which dynamically adjusts in response to environmental changes to maintain filtration barrier integrity. The slit diaphragms bridge the filtration slits between neighboring foot processes and act as signaling hubs interacting with the actin cytoskeleton. Focal adhesions relay signals to regulate actin dynamics while allowing podocyte adherence to the basement membrane. Mutations in actin regulatory and signaling proteins may disrupt the actin cytoskeleton, resulting in foot process retraction, effacement, and proteinuria. Large-scale gene expression profiling platforms, transgenic animal models, and other in vivo gene delivery methods now enhance our understanding of the interactions among podocyte focal adhesions, slit diaphragms, and actin dynamics. In addition, our team found that at least 66% of idiopathic nephrotic syndrome (INS) children have podocyte autoantibodies, which was defined as a new disease subgroup-, autoimmune podocytopathies. This review outlines the pathophysiological mechanisms of podocyte cytoskeleton protein interactions in proteinuria and glomerular podocytopathy.

The therapeutic effects of human embryonic stem cells-derived immunity-and-matrix regulatory cells on membranous nephropathy

Background

Primary membranous nephropathy (MN) is a kidney-specific autoimmune disease. Human embryonic stem cells-derived immunity-and-matrix regulatory cells (hESC-IMRCs) have immunoregulatory functions. We hypothesized that hESC-IMRCs might have therapeutic effects on MN and be a potential treatment in clinical practice.

Methods

Rats of Heymann nephritis were injected with sheep anti-rat Fx1A serum. hESC-IMRCs were intravenously administrated upon the detection of proteinuria, with 6 × 10⁶ cells (high-dose) or 3 × 10⁶ cells (low-dose) in 1 ml every other day. Splenocytes and IMRCs were co-cultured at different times and ratios. Cell types and cytokines were detected by flow cytometry and enzyme-linked immunosorbent assay.

Results

The urinary protein of rats with Heymann nephritis was reduced remarkably to a level comparable to negative controls, in both low-dose (45.6 vs. 282.3 mg/d, P < 0.001) and high-dose (35.2 vs. 282.3 mg/d, P < 0.001) hESC-IMRC treatment groups. IgG and C3 deposit, glomerular basement membrane thickness and foot process effacement were alleviated and the reduced podocin was recovered in the kidneys. The proportions of CD4 + CD25 + T cells in circulation and spleen were increased, and the circulating level of IL-10 was increased, after IMRC interventions. IL-17 and TNF-α were reduced after IMRCs treatments. IL-10 increased remarkably in the co-culture supernatant of lymphocytes and IMRCs at 48 h with ratio 10:1.

Conclusions

The intravenously delivered hESC-IMRCs alleviated proteinuria and kidney injuries of Heymann nephritis, by their immunosuppressive functions through regulatory T cells and IL-10. These pre-clinical results indicate that IMRCs worth careful consideration for human trials in the treatment of MN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02917-w.

The immunopathogenesis of idiopathic nephrotic syndrome: a narrative review of the literature

Idiopathic nephrotic syndrome (INS) is a common glomerular disease in childhood, and the immunological involvement in the pathogenesis of non-genetic INS, although not fully elucidated, is evident. This narrative review aims to offer a concise and in-depth view of the current knowledge on the immunological mechanisms of the development of INS as well as the role of the immunological components of the disease in the responsiveness to treatment. T cell immunity appears to play a major role in the INS immunopathogenesis and has been the first to be linked to the disease. Various T cell immunophenotypes are implicated in INS, including T-helper-1, T-helper-2, T-helper-17, and T regulatory cells, and various cytokines have been proposed as surrogate biomarkers of the disease; however, no distinct T helper or cytokine profile has been conclusively linked to the disease. More recently, the recognition of the role of B cell mediated immunity and the various B cell subsets that are dysregulated in patients with INS have led to new hypotheses on the underlying immunological causes of INS. Finally, the disambiguation of the exact mechanisms of the INS development in the future may be the key to the development of more targeted personalized approaches in managing INS.

CONCLUSIONS

INS demonstrates particularly interesting immunopathogenetic pathways, in which multiple interactions between T cell and B cell immunity and the podocyte are involved. The disambiguation of these pathways will provide promising novel therapeutic targets in INS.

WHAT IS KNOWN

• INS is the most common glomerular disease in the paediatric population, and its onset and relapses have been linked to various immunological triggers. • Multiple immunological mechanisms have been implicated in the pathogenesis of INS; however, no single distinct immunological profile has been recognized.

WHAT IS NEW

• Th17 cells and Treg cells play an important role in the immune dysregulation in INS. • Transitional B cell levels as well as the transitional/memory B cell ratio have been correlated to nephrotic relapses and have been proposed as biomarkers of INS relapses in SSNS patients.

New Insights into the Treatment of Glomerular Diseases: When Mechanisms Become Vivid

Treatment for glomerular diseases has been extrapolated from the experience of other autoimmune disorders while the underlying pathogenic mechanisms were still not well understood. As the classification of glomerular diseases was based on patterns of juries instead of mechanisms, treatments were typically the art of try and error. With the advancement of molecular biology, the role of the immune agent in glomerular diseases is becoming more evident. The four-hit theory based on the discovery of gd-IgA1 gives a more transparent outline of the pathogenesis of IgA nephropathy (IgAN), and dysregulation of Treg plays a crucial role in the pathogenesis of minimal change disease (MCD). An epoch-making breakthrough is the discovery of PLA2R antibodies in the primary membranous nephropathy (pMN). This is the first biomarker applied for precision medicine in kidney disease. Understanding the immune system's role in glomerular diseases allows the use of various immunosuppressants or other novel treatments, such as complement inhibitors, to treat glomerular diseases more reasonable. In this era of advocating personalized medicine, it is inevitable to develop precision medicine with mechanism-based novel biomarkers and novel therapies in kidney disease.

The Role of Cytokines in Nephrotic Syndrome

Idiopathic nephrotic syndrome (INS) is an important primary glomerular disease characterized by severe proteinuria. Evidence supports a role for T cell dysfunction in the pathogenesis of INS. Glucocorticoids are the primary therapy for INS; however, steroid-resistant NS (SRNS) patients are at a higher risk of drug-induced side effects and harbor poor prognosis. Although the exact mechanism of the resistance is unknown, the imbalances of T helper subtype 1 (Th1), Th2, and regulatory T cells (Tregs) and their cytokines may be involved in the pathogenesis of glucocorticoid responsiveness. Up to now, no confirmed biomarkers have been able to predict SRNS; however, a panel of cytokines may predict responsiveness and identify SRNS patients. Thus, the introduction of distinctive cytokines as novel biomarkers of SRNS enables both preventions of drug-related toxicity and earlier switch to more effective therapies. This review highlights the impacts of T cell population imbalances and their downstream cytokines on response to glucocorticoid responsiveness state in INS.

Imbalanced Th17/Treg in peripheral blood of adult patients with immunoglobulin A vasculitis nephritis

Introduction

Adult immunoglobulin A vasculitis nephritis (IgAVN) was observed to be more severe than the disease in children because it tended to result in a poor prognosis. The present study analyzed the Th17/Treg cell axis in peripheral blood of adult IgAVN patients, aiming to provide new immunological viewpoints for the pathogenesis of adult IgAVN.

Material and methods

Th17 cell and Treg cell frequencies in peripheral blood of healthy subjects (n = 13) and adult IgAVN patients (n = 12) were analyzed by flow cytometry. Foxp3 mRNA in peripheral blood of healthy subjects and adult IgAVN patients was detected by RT-PCR. Interleukin (IL)-17 and IL-10 in peripheral blood serum of healthy subjects and adult IgAVN patients were examined by ELISA.

Results

The percentages of CD4⁺ Th17⁺ cells in peripheral blood of healthy subjects and adult IgAVN patients were 2.65 ±1.55% and 4.37 ±1.68% respectively. The percentages of Treg cells in peripheral blood of healthy subjects and adult IgAVN patients were 6.44 ±2.90% and 3.91 ±1.94% respectively. The ratio of Th17/Treg in adult IgAVN patients was significantly higher than that of healthy subjects (p = 0.0030). Meanwhile, the Foxp3 mRNA expression of adult IgAVN patients was significantly lower than that of healthy subjects. There was a significant difference in the ratio of IL-17/IL-10 between healthy subjects and adult IgAVN patients (p < 0.0001). A significant correlation between red blood cell distribution width (RDW) and the ratio of Th17/Treg in adult IgAVN patients was observed in Spearman correlation analysis (r = 0.6970, p = 0.0145).

Conclusions

Imbalanced Th17/Treg contributed to the complex pathogenesis of adult IgAVN.

Overexpression of P-glycoprotein and MRP-1 are pharmacogenomic biomarkers to determine steroid resistant phenotype in childhood idiopathic nephrotic syndrome

Steroid remains the keystone therapy for Idiopathic Nephrotic Syndrome (NS). Besides genetic factors and histological changes, pharmacogenomic factors also affect the steroid response. The upregulation of P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP-1) modulate the pharmacokinetics of steroids and may contribute to steroid resistance. Flow-cytometric analysis of P-gp, MRP-1 expression and functional activity on peripheral blood mononuclear cells (PBMCs) was carried out in steroid-sensitive nephrotic syndrome (SSNS) (n = 171, male 103, mean age = 8.54 ± 4.3); and steroid-resistant nephrotic syndrome (SRNS) (n = 83, male 43, mean age = 7.43 ± 4.6) patients. The genotypings of MDR-1 gene were carried out using PCR-RFLP. We observed that the percentage expression of P-gp (10.01 ± 2.09 and 3.79 ± 1.13, p < 0.001); and MRP-1 (15.91 ± 3.99 and 7.40 ± 2.33, p < 0.001) on lymphocyte gated population were significantly higher in SRNS than that of SSNS. The functional activity of P-gp and MRP-1 was also significantly escalated in SRNS as compared to SSNS (68.10 ± 13.35 and 28.93 ± 7.57, p < 0.001); (72.13 ± 8.34 and 31.56 ± 8.65, p < 0.001) respectively. AUC-ROC curve analysis revealed that P-gp and MRP-1 expression with a cut-off value of 7.13% and 9.62% predicted SRNS with the sensitivity of 90% and 80.7%; and specificity 90% and 80%, respectively. Moreover, MDR-1 homozygous mutant TT+AA for G2677T/A (rs2032582) was significantly associated with SRNS (p = 0.025, OR = 2.86 CI = 1.14-7.14). The expression of P-gp (9.68 ± 4.99 v/s 5.88 ± 3.38, p = 0.002) was significantly higher in the patients of homozygous mutant alleles compared to wildtype GG. The increased expression and functionality of P-gp and MRP-1 contribute to steroid resistance, and MDR-1 homozygous mutant G2677T/A promotes steroid resistance by inducing P-gp expression in NS.

Efficacy of rituximab in thymoma associated minimal change disease: case report

Background

Thymomas have been associated with a broad spectrum of autoimmune diseases. Minimal change disease (MCD) is the most frequent pathological lesion reported. Pathophysiological mechanisms involved in secondary MCD, and linking MCD to thymoma are not yet fully explained, although the hypothesis of T cell dysfunction has been suggested. The fundamental therapeutic principles are steroids and surgical treatment of thymoma, but failures and relapses often require immunosuppressant combinations.

Case presentation

A 62-year-old female was admitted in our unit for a nephrotic syndrome associated with a thymoma. The diagnosis of thymoma associated MCD was confirmed by kidney biopsy. After surgical resection of the thymoma and steroid therapy, no remission was observed. Immunosuppressive therapy was then intensified with introduction of rituximab. Here, we report a steroid-resistant nephrotic syndrome secondary to MCD associated thymoma, which achieved complete remission after rituximab therapy. To the best of our knowledge, this is the first report of the use and efficacy of rituximab therapy in this pathology.

Conclusions

Our case report suggests that primary and secondary MCD may share similar pathophysiological mechanisms. It does not allow us to draw any conclusions about the mechanism of action of rituximab, but we believe this report argues for the safety and efficacy of rituximab use in thymoma-associated MCD, and therefore constitutes a rationale for future studies.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

Novel insights in the genetics of steroid-sensitive nephrotic syndrome in childhood

Steroid-sensitive nephrotic syndrome (SSNS) is the most common form of nephrotic syndrome in childhood and there is growing evidence that genetics play a role in the susceptibility for the disease. Familial clustering has been observed and has led to several studies on familial SSNS trying to identify a monogenic cause of the disease. Until now, however, none of these have provided convincing evidence for Mendelian inheritance. This and the phenotypic variability within SSNS suggest a complex inheritance pattern, where multiple variants and interactions between those and the environment play roles in disease development. Genome-wide association studies (GWASs) have been used to investigate this complex disease. We herein highlight new insights in the genetics of the disease provided by GWAS and identify how these insights fit into our understanding of the pathogenesis of SSNS.

CMIP interacts with WT1 and targets it on the proteasome degradation pathway

BACKGROUND

The Wilms tumor 1 suppressor gene, WT1, is expressed throughout life in podocytes and is essential for their function. Downregulation of WT1 has been reported in podocyte diseases but the underlying mechanisms remain unclear. Podocyte injury is the hallmark of idiopathic nephrotic syndrome (INS), the most frequent glomerular disease in children and young adults. An increase in the abundance of Cmaf-inducing protein (CMIP) has been found to alter podocyte function, but it is not known whether CMIP affects WT1 expression.

METHODS

Transcriptional and post-transcriptional regulation of WT1in the presence of CMIP was studied using transient transfection, mouse models, and siRNA handling.

RESULTS

We showed that overproduction of CMIP in the podocyte was consistently associated with a downregulation of WT1 according to two mechanisms. We found that CMIP prevented the NF-kB-mediated transcriptional activation of WT1. We demonstrated that CMIP interacts directly with WT1 through its leucine-rich repeat domain. Overexpression of CMIP in the M15 cell line induced a downregulation of WT1, which was prevented by lactacystin, a potent proteasome inhibitor. We showed that CMIP exhibits an E3 ligase activity and targets WT1 to proteasome degradation. Intravenous injection of Cmip-siRNA specifically prevented the repression of Wt1 in lipopolysaccharides-induced proteinuria in mice.

CONCLUSIONS

These data suggest that CMIP is a repressor of WT1 and might be a critical player in the pathophysiology of some podocyte diseases. Because WT1 is required for podocyte integrity, CMIP could be considered a therapeutic target in podocyte diseases.

The immune cell landscape of peripheral blood mononuclear cells from PNS patients

Existing research suggests that the human immune system and immune cells are involved in the pathogenesis of nephrotic syndrome, but there is still a lack of direct evidence. This study tried to analyze the profiling of immune cells in the peripheral blood of steroid-sensitive nephrotic syndrome (SSNS) patients and steroid-resistant nephrotic syndrome (SRNS) patients before and after standard steroid treatment to clarify the immunological mechanism of nephrotic syndrome patients. The number and proportion of CD4 + T cells in patients with nephrotic syndrome remained unchanged. However, there is an imbalance of Th1 and Th2 and an excessive increase of Th17 cells. The number of CD8 + T cells and the number of effector CD8 + T cells in them increased significantly, but only in SSNS, the number of activated CD8 + T cells increased, and the number of activated T_reg cells decreased significantly. Nephrotic syndrome patients also have B cell disorder, and it is more prominent in SSNS patients. Compared with the normal control, only the number of B cells and plasmablast in SSNS patients increased significantly (Z = − 2.20, P = 0.028). This study also observed that transitional B cells decreased in both SSNS and SRNS patients, but SSNS patients' decrease was lower than in SRNS patients. Compared with normal controls, monocytes in patients with nephrotic syndrome decreased significantly. The main reason was that Non-classical Monocyte decreased, while Classical Monocyte increased slightly. The total number of NK cells did not change, but the internal cell subgroups' composition occurred. Changes, realized as CD56hi NK cells increased, CD56low NK cells decreased; and the above trend is more evident in SSNS patients. Patients with nephrotic syndrome have immune disorders, including T cells, B cells, Monocytes, and NK cells. It can be confirmed that immune factors are involved in the pathogenesis of the nephrotic syndrome.

Circulating plasmablasts and high level of BAFF are hallmarks of minimal change nephrotic syndrome in adults

BACKGROUND

The recent success achieved with the use of B cell-depleting agents in some patients with minimal change nephrotic syndrome (MCNS) suggests an unexpected role for B lymphocytes in the pathogenesis of this immune-mediated glomerular disease. Nevertheless, no extensive B-cell phenotyping analysis has ever been performed in untreated adult patients soon after MCNS diagnosis.

METHODS

We investigated the distribution of the different B-cell subpopulations in 22 untreated adult patients with biopsy-proven MCNS [MCNS relapse (MCNS-Rel)]. We compared these data with those for 24 healthy controls, 13 MCNS patients in remission (with no specific treatment) and 19 patients with idiopathic membranous nephropathy (IMN).

RESULTS

Patients with MCNS-Rel or IMN had higher proteinuria and lower serum albumin and gammaglobulin levels (P < 0.0001 for all comparisons) than MCNS patients in remission. Plasmablasts were the only B-cell subsets present at significantly higher levels in MCNS-Rel patients than in the patients of the other three groups (P < 0.05 for all comparisons). The lower albumin levels and higher proteinuria levels were positively correlated with the percentage of circulating plasmablasts (Spearman test's ρ = -0.54, P = 0.01 and ρ = 0.65, P = 0.002, respectively). Similarly, the increase of immunoglobulin M (IgM) and the decrease of IgG levels were significantly associated with the percentage of plasmablasts in MCNS-Rel patients (Spearman's ρ = 0.36, P = 0.01 and Spearman's ρ = -0.60, P = 0.01, respectively). Increased production of interleukin (IL)-21, IL-6 and B-cell activating factor (BAFF) in the serum of MCNS-Rel patients was found significantly correlated with the percentage of plasmablasts (ρ = 0.72, P = 0.0002, ρ = 0.49, P = 0.04 and ρ = 0.62, P = 0.009, respectively).

CONCLUSIONS

An increase in the proportion of circulating plasmablasts seems to be a hallmark of untreated MCNS in adult patients. Further studies are required to more precisely determine the phenotype and functions of these cells.

Immunological Impact of a Gluten-Free Dairy-Free Diet in Children With Kidney Disease: A Feasibility Study

Kidney disease affects 10% of the world population and is associated with increased mortality. Steroid-resistant nephrotic syndrome (SRNS) is a leading cause of end-stage kidney disease in children, often failing standard immunosuppression. Here, we report the results of a prospective study to investigate the immunological impact and safety of a gluten-free and dairy-free (GF/DF) diet in children with SRNS. The study was organized as a four-week summer camp implementing a strict GF/DF diet with prospective collection of blood, urine and stool in addition to whole exome sequencing WES of DNA of participants. Using flow cytometry, proteomic assays and microbiome metagenomics, we show that GF/DF diet had a major anti-inflammatory effect in all participants both at the protein and cellular level with 4-fold increase in T regulatory/T helper 17 cells ratio and the promotion of a favorable regulatory gut microbiota. Overall, GF/DF can have a significant anti-inflammatory effect in children with SRNS and further trials are warranted to investigate this potential dietary intervention in children with SRNS.

Idiopathic nephrotic syndrome in children: role of regulatory T cells and gut microbiota

BACKGROUND

We investigated whether an association exists between regulatory T cells (Tregs) during initial presentation in children with idiopathic nephrotic syndrome (INS) and later development of frequently relapsing INS.

METHODS

Blood samples were obtained at onset and at remission from 25 patients (median age, 4.0 years) with INS; eight did not show relapse after initial response (non-relapsing [NR]), whereas 17 showed frequent relapses (frequently relapsing [FR]). Tregs were measured by flow cytometry; increases were compared between groups. Fecal samples were obtained at onset from 20 patients with INS, as well as from 20 age-matched healthy children. Gut microbiota composition was assessed using 16S ribosomal RNA (rRNA) sequencing (ion PGM).

RESULTS

The rate of increase in Tregs from onset to remission was significantly lower in the FR group (124.78%) than in the NR group (879.16%; P < 0.001). Additionally, 16S rRNA sequencing of gut microbiota showed that the proportion of butyric acid-producing bacteria was significantly lower in the FR group (7.08%) than in the healthy children (17.45%; P < 0.001).

CONCLUSIONS

In children with INS, small increases in Tregs in response to steroid treatment were associated with subsequent increased risk of frequent relapses. In addition, the FR group had a greater degree of dysbiosis at onset.

IMPACT

A low rate of Tregs increase is associated with subsequent frequent relapses of INS. The increase in Tregs in response to steroid treatment was small when dysbiosis was present in patients with INS, particularly when the proportion of butyrate-producing bacteria was considerably reduced We presume that improvement of dysbiosis by administration of probiotics and prebiotics may enhance the rate of Tregs' increase, thus preventing frequent relapse.

T helper 17 cells in the pathophysiology of acute and chronic kidney disease

Both acute and chronic kidney disease have a strong underlying inflammatory component. This review focuses primarily on T helper 17 (Th17) cells as mediators of inflammation and their potential to modulate acute and chronic kidney disease. We provide updated information on factors and signaling pathways that promote Th17 cell differentiation with specific reference to kidney disease. We highlight numerous clinical studies that have investigated Th17 cells in the setting of human kidney disease and provide updated summaries from various experimental animal models of kidney disease indicating an important role for Th17 cells in renal fibrosis and hypertension. We focus on the pleiotropic effects of Th17 cells in different renal cell types as potentially relevant to the pathogenesis of kidney disease. Finally, we highlight studies that present contrasting roles for Th17 cells in kidney disease progression.

Short-Duration Prednisolone in Children with Nephrotic Syndrome Relapse: A Noninferiority Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

In children with nephrotic syndrome, steroids are the cornerstone of therapy for relapse. The adequate duration and dosage of steroids, however, have not been an active area of research, especially in children with infrequently relapsing nephrotic syndrome. This study investigated the efficacy of an abbreviated regimen for treatment of a relapse in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a single-center, open-label, randomized controlled trial, we evaluated the efficacy of prednisolone as a "short regimen" (40 mg/m² on alternate days for 2 weeks) compared with "standard regimen" (40 mg/m² on alternate days for 4 weeks) for children aged 1-16 years who achieved remission of a relapse. The primary outcome was the proportion of children developing frequent relapses or steroid dependence at 12 months.

RESULTS

A total of 117 patients were enrolled and randomized to short (55) or standard (62) regimen. Fourteen (24%) patients in standard regimen and 12 (23%) in short regimen developed frequent relapses or steroid dependence over a period of 1 year (risk difference, -1%; 95% confidence interval, -15 to 16; P=0.90). A large 95% confidence interval crossed the proposed noninferiority margin. In a time to event analysis, there was no significant difference in the proportion of children developing frequent relapses or steroid dependence and time to outcome between the two groups (hazard ratio, 1.01; 95% confidence interval, 0.83 to 1.23; P=0.98). Time to relapse, relapse rate, and steroid-related adverse events were similar in both groups. Cumulative steroid exposure was significantly lower in the short regimen (risk difference, -541 mg/m²; 95% confidence interval, -917 to -164 mg/m²; P<0.001).

CONCLUSIONS

In children with infrequently relapsing nephrotic syndrome, a short steroid treatment for relapse resulted in a similar proportion of patients developing frequent relapses or steroid dependence; however, noninferiority of a short regimen was not established.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

CTRI/2015/11/006345.

Rituximab Induces Complete Remission of Proteinuria in a Patient With Minimal Change Disease and No Detectable B Cells

Minimal change disease (MCD) is a common cause of nephrotic syndrome. Treatment with steroids is usually effective, but frequent relapses are therapeutic challenges. The anti-CD20 antibody rituximab has shown promising results for treatment of steroid-sensitive nephrotic syndrome. Since predictive biomarkers for treatment efficacy and the accurate rituximab dosage for effective induction of remission are unknown, measurement of CD19+ B cells in blood is often used as marker of successful B cell depletion and treatment efficacy. A male patient with relapsing MCD was successfully treated with rituximab, but developed relapse of proteinuria 1 year later, although no B cells were detectable in his blood. B and T cell populations in the patient's blood were analyzed before and after treatment with rituximab using FACS analysis. Rituximab binding to B and T cells were measured using Alexa Fluor 647 conjugated rituximab. We identified a population of CD20+ CD19- cells in the patient's blood, which consisted mostly of CD20+ CD3+ T cells. Despite the absence of B cells in the blood, the patient was again treated with rituximab. He developed complete remission of proteinuria and depletion of CD20+ T cells. In a control patient with relapsing MCD initial treatment with rituximab led to depletion of both CD20+ B and T cells. Rituximab induces remission of proteinuria in patients with MCD even if circulating B cells are absent. CD20+ T cells may play a role in the pathogenesis of MCD and might be a promising treatment target in patients with MCD.

The Effect of Interleukin-4 and Dexamethasone on RNA-Seq-Based Transcriptomic Profiling of Human Podocytes: A Potential Role in Minimal Change Nephrotic Syndrome

Interleukin-4 (IL-4) expression is implicated in the pathogenesis of nephrotic syndrome (NS). This study aimed to investigate the changes in the transcriptomes of human podocytes induced by IL-4 treatment and to analyze whether these changes could be affected by simultaneous steroid treatment. Three groups of human podocytes were treated with control, IL-4, and IL-4 plus dexamethasone (DEX), respectively. We performed whole-transcriptome sequencing to identify differentially expressed genes (DEGs) between the groups. We investigated relevant biological pathways using Gene Ontology (GO) enrichment analyses. We also attempted to compare and validate the DEGs with the genes listed in PodNet, a literature-based database on mouse podocyte genes. A total of 176 genes were differentially expressed among the three groups. GO analyses showed that pathways related to cytoskeleton organization and cell signaling were significantly enriched. Among them, 24 genes were listed in PodNet, and 12 of them were previously reported to be associated with IL-4-induced changes in human podocytes. Of the 12 genes, the expression levels of BMP4, RARB, and PLCE1 were reversed when podocytes were simultaneously treated with DEX. In conclusion, this study explored changes in the transcriptome profiles of human podocytes treated with IL-4. Few genes were reported in previous studies and were previously validated in experiments with human podocytes. We speculate that IL-4 may exert pathogenic effects on the transcriptome of human podocytes, and a few genes may be involved in the pathogenesis.

Urinary CD80 Discriminates Among Glomerular Disease Types and Reflects Disease Activity

Introduction

Heterogeneity of nephrotic diseases and a lack of validated biomarkers limits interventions and reduces the ability to examine outcomes. Urinary CD80 is a potential biomarker for minimal change disease (MCD) steroid-sensitive nephrotic syndrome (NS). We investigated and validated a CD80 enzyme-linked immunosorbent assay (ELISA) in urine in a large cohort with a variety of nephrotic diseases.

Methods

A commercial CD80 ELISA was enhanced and analytically validated for urine. Patients were from Mayo Clinic (307) and Nephrotic Syndrome Study Network Consortium (NEPTUNE; 104) as follows: minimal change disease (MCD, 56), focal segmental glomerulosclerosis (FSGS, 92), lupus nephritis (LN, 25), IgA nephropathy (IgAN, 20), membranous nephropathy (MN, 49), autosomal dominant polycystic kidney disease (ADPKD, 10), diabetic nephropathy (DN; 106), pyuria (19), and controls (34). Analysis was by Kruskal−Wallis test, generalized estimating equation (GEE) models, and receiver operating characteristic (AUC) curve.

Results

Urinary CD80/creatinine values were highest in MCD compared to other glomerular diseases and were increased in DN with proteinuria >2 compared to controls (control = 36 ng/g; MCD = 139 ng/g, P < 0.01; LN = 90 ng/g, P < 0.12; FSGS = 66 ng/g, P = 0.18; DN = 63, P = 0.03; MN = 69 ng/g, P = 0.33; ng/g, P = 0.07; IgA = 19 ng/g, P = 0.09; ADPKD = 42, P = 0.36; and pyuria 31, P = 0.20; GEE, median, P vs. control). In proteinuric patients, CD80 concentration appears to be independent of proteinuria levels, suggesting that it is unrelated to nonspecific passage across the glomeruli. CD80/creatinine values were higher in paired relapse versus remission cases of MCD and FSGS (P < 0.0001, GEE).

Conclusion

Using a validated ELISA, urinary CD80 levels discriminate MCD from other forms of NS (FSGS, DN, IgA, MN) and primary from secondary FSGS.

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 balance of proinflammatory cytokines and Treg cells in chronic glomerulonephritis]

Chronic glomerulonephritis (CGN) is a disease with a steadily progressing course, which is based on inflammation with the activation of immune cells. The severity of the inflammatory reaction in the kidney tissue is determined by the balance of locally pro-inflammatory factors and protective mechanisms, which include anti-inflammatory cytokines and T-regulatory lymphocytes (Treg). The study of processes that can modulate the severity of inflammation in the kidney is of particular interest for understanding the basic patterns of CGN progression.

AIM

To determine the clinical significance of the Th17, Th1, and Treg cytokines in urine to assess the activity and progression of chronic glomerulonephritis with nephrotic syndrome (NS).

MATERIALS AND METHODS

The study included 98 patients with CGN 37 women and 61 men. Patients were divided into two groups according to the degree of CGN activity. Group I consisted of 51 patients with NS. In 21 subjects, a decrease in GFR60 ml/min was revealed. Group II included 47 patients with proteinuria from 1 to 3 g/day without NS. GFR60 ml/min/1.73 m2 was observed in 26 patients. A kidney biopsy was performed in 65 patients and the hystological diagnosis was verified: 20 had mesangioproliferative GN, 16 had membranous nephropathy, 18 had focal segmental glomerulosclerosis, and 11 had membranoproliferative GN. The control group consisted of 15 healthy people. The levels of IL-6, IL-10, IL-17, tumor necrosis factor a (TNF-a) in the urine were determined using enzyme-linked immunosorbent assay. The number of FoxP3-positive cells in the inflammatory interstitial infiltrate of the cortical layer was determined in 39 patients (in a biopsy sample in a 1.5 mm2 area).

RESULTS

In group of patients with CGN, there was an increase in the levels of Th17, Th1, and Treg cytokines in urine TNF-a and IL-10 compared with healthy individuals. An increase in the levels of IL-6 in the urine of patients with high clinical activity of CGN (with NS and renal dysfunction) was more pronounced than in patients with NS and normal renal function. There was a decrease in the number of Treg cells in the interstitium of the kidney and a decrease in the production of anti-inflammatory IL-10 in CGN patients with NS, compared with patients without NS. The most pronounced changes in the cytokine profile were observed in patients with FSGS with an increase in pro-inflammatory cytokines and a decrease in Treg in the kidney tissue/anti-inflammatory IL-10 in the urine.

CONCLUSION

An imbalance of cytokines characterized by an increased levels of pro-inflammatory IL-17, IL-6, TNF-a, and a reduced levels of anti-inflammatory IL-10 and T-regulatory cells in the kidney tissue is noted in patients with NS, especially with FSGS. Imbalance of cytokines reflects the high activity of CGN and the risk of the progression of the disease.

Calcium channel Orai1 promotes lymphocyte IL-17 expression and progressive kidney injury

We hypothesized that the store-operated calcium entry (SOCE) channel, Orai1, participates in the activation of Th17 cells and influences renal injury. In rats, following renal ischemia/reperfusion (I/R), there was a rapid and sustained influx of Orai1+ CD4 T cells and IL-17 expression was restricted to Orai1+ cells. When kidney CD4+ cells of post-acute kidney injury (post-AKI) rats were stimulated with angiotensin II and elevated Na+ (10-7 M/170 mM) in vitro, there was an enhanced response in intracellular Ca2+ and IL-17 expression, which was blocked by SOCE inhibitors 2APB, YM58483/BTP2, or AnCoA4. In vivo, YM58483/BTP2 (1 mg/kg) attenuated IL-17+ cell activation, inflammation, and severity of AKI following either I/R or intramuscular glycerol injection. Rats treated with high-salt diet (5-9 weeks after I/R) manifested progressive disease indicated by enhanced inflammation, fibrosis, and impaired renal function. These responses were significantly attenuated by YM58483/BTP2. In peripheral blood of critically ill patients, Orai1+ cells were significantly elevated by approximately 10-fold and Th17 cells were elevated by approximately 4-fold in AKI versus non-AKI patients. Further, in vitro stimulation of CD4+ cells from AKI patients increased IL-17, which was blocked by SOCE inhibitors. These data suggest that Orai1 SOCE is a potential therapeutic target in AKI and CKD progression.

LPS-Treated Podocytes Polarize Naive CD4+ T Cells into Th17 and Treg Cells

Aim

Our study is aimed at investigating whether Lipopolysaccharide- (LPS-) treated podocytes could polarize naive CD4⁺ T cells into different subsets in vitro.

Materials and Methods

Podocytes and mouse bone marrow-derived dendritic cells (BMDCs) were first cultured with 25 μg/ml LPS for 6 hours, respectively. Then, naive CD4⁺ T cells were cocultured with the LPS-treated podocytes or BMDCs at a ratio of 1 : 1 or 1 : 1 : 1. After 48 hours, we collected the suspended cells and supernatant from all groups to measure T helper (Th)17 cells, regulatory T (Treg) cells, and cytokine concentration.

Results

We observed the expression of CD80 and major histocompatibility complex class II molecule (MHC II) in podocytes but did not found the upregulation of them after treating podocytes with LPS. LPS-treated podocytes could induce naive CD4⁺ T cells to Th17 cells and Treg cells with a higher ratio of Th17/Treg than BMDCs. Possible interaction between podocytes and BMDCs may exist in the induction process of Th17 cells and Treg cells.

Conclusion

Our study proved that CD80 and MHC II were constitutively expressed in podocytes but not upregulated by LPS. LPS-treated podocytes could polarize naive CD4⁺ T cells into Th17 and Treg cells and affect the Th17/Treg balance and may incline to cause a Th17 response.

Corticosteroid reduction by addition of cetirizine and montelukast in biopsy-proven minimal-change nephrotic syndrome concomitant with allergic disorders

Recent reports suggest helper T-cell abnormalities in minimal-change nephrotic syndrome (MCNS), which often complicate allergic disorders that show a similar helper T-cell profile with Th2/Th17 predominance. However, the effect of anti-allergy therapy on MCNS remains unknown. This retrospective study included 51 patients with biopsy-proven MCNS recruited between November 2012 and October 2015, with follow-up through November 2017. We analyzed relapse and temporal daily corticosteroid dose with and without co-administration of histamine H1 receptor antagonist, cetirizine, and cysteinyl-leukotriene receptor antagonist, montelukast, as well as between baseline and after follow-up. Thirteen patients were treated with cetirizine and montelukast in addition to conventional therapy, whereas 38 patients were treated by conventional therapy only, consisting of corticosteroids and immunosuppressants. To adjust for baseline clinical characteristics, a 1:1 propensity score–matched model was applied. The clinical characteristics of the two groups after matching were similar at baseline. The treatment group showed a significant reduction in the lowest daily dose of oral prednisolone throughout the entire treatment course after the study compared to that of baseline (p < 0.025), which was not observed in the control group (p = 0.37), and showed significantly higher percentage of patients establishing corticosteroid-free state for the first time throughout the entire treatment course by addition of cetirizine and montelukast compared to the control group (p < 0.025). The study shows, for the first time, the steroid sparing effect of cetirizine and montelukast in addition to conventional treatment in MCNS patients with concomitant allergies.

Compositional alterations of gut microbiota in children with primary nephrotic syndrome after initial therapy

Background

Primary nephrotic syndrome (PNS) is a common glomerular disease in children. T cell dysfunction plays a crucial role in the pathogenesis of PNS. Moreover, dysbiosis of gut microbiota contributes to immunological disorders. Whether the initial therapy of PNS affects gut microbiota remains an important question. Our study investigated compositional changes of gut microbiota after initial therapy.

Methods

Fecal samples of 20 children with PNS were collected before and after 4-week initial therapy. Total bacteria DNA were extracted and the V3-V4 regions of bacteria 16S ribosomal RNA gene were sequenced. The composition of gut microbiota before and after initial therapy was analyzed by bioinformatics methods. The function of altered gut microbiota was predicted with PICRUSt method.

Results

The richness and diversity of gut microbiota were similar before and after 4-week initial therapy. Gut microbiota at the phylum level was dominated by four phyla including Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria, but the increased relative abundance after initial therapy was found in Deinococcus-Thermus and Acidobacteria. At the genus level, the increased abundance of gut microbiota after initial therapy was observed in short chain fat acids (SCFA)-producing bacteria including Romboutsia, Stomatobaculum and Cloacibacillus (p < 0.05). Moreover, the predicted functional profile of gut microbiota showed that selenocompound metabolism, isoflavonoid biosynthesis and phosphatidylinositol signaling system weakened after initial therapy of PNS.

Conclusions

Initial therapy of PNS increased SCFA-producing gut microbiota, but might diminish selenocompound metabolism, isoflavonoid biosynthesis and phosphatidylinositol signaling system in children.

Pathologic tonsillar findings similar to IgA nephropathy and the role of tonsillectomy in a patient with nephrotic syndrome

BACKGROUND

The pathological findings of tonsils in IgA nephropathy include the expansion of T-cell nodules around lymphoid follicles and abnormal reticulation of the crypt epithelium in contrast to chronic tonsillitis. Recently, several studies have reported that regulatory T cells play an important role in the maintenance of self-tolerance, an abnormality that is involved in the onset of nephrotic syndrome (NS). We encountered a patient of 28-year-old male with frequently relapsing nephrotic syndrome (FRNS) and chronic tonsillitis whose tonsils demonstrated pathological findings similar to those of IgA nephropathy.

CASE PRESENTATION

A patient had developed NS at the age of 5 years, and was pathologically diagnosed with minimal change disease (MCD), for which he received various immunosuppressive agents as treatment for recurrence. Because tonsillitis often triggers the recurrence of NS, a tonsillectomy was performed for chronic tonsillitis at the age of 25 years. Immunohistochemical staining of his tonsils showed the expansion of CD4 positive lymphocytes around the lymphoid follicles and abnormal reticulation of the crypt epithelium. The number of peripheral blood CD4+CD25+ regulatory T cells increased, and the frequency of relapses decreased after tonsillectomy.

CONCLUSION

A similar self-tolerance abnormality exists in NS and IgA nephropathy; therefore, tonsillectomy might become a novel therapeutic approach for FRNS to redress the unbalanced self-tolerance and to remove the tonsillar focal infection. Further studies are necessary to verify the clinical efficiency of tonsillectomy for FRNS with recurrent episodes triggered by tonsillitis.

Human Th17 cells produce a soluble mediator that increases podocyte motility via signaling pathways that mimic PAR-1 activation

The specific pathogenesis of idiopathic nephrotic syndrome (NS) is poorly understood, and the role of immune mediators remains contentious. However, there is good evidence for the role of a circulating factor, and we recently postulated circulating proteases as candidate factors. Immunosuppressive therapy with glucocorticoids (GCs) and T cell inhibitors are widely used in the clinical treatment of NS. Given that T helper (CD4⁺) cells expressing IL-17A (so-called Th17 cells) have recently been reported to be resistant to GC treatment, and GC resistance remains a major challenge in the management of NS, we hypothesized that Th17 cells produce a circulating factor that is capable of signaling to the podocyte and inducing deleterious phenotypic changes. To test this, we generated human Th17 cells from healthy volunteers and added the supernatants from these T cell cultures to conditionally immortalized human podocytes in vitro. This demonstrated that podocytes treated with Th17 cell culture supernatant, as well as with patient disease plasma, showed significant stimulation of JNK and p38 MAPK pathways and an increase in motility, which was blocked using a JNK inhibitor. We have previously shown that nephrotic plasma elicits a podocyte response via protease-activated receptor-1 (PAR-1). Stimulation of PAR-1 in podocytes elicited the same signaling response as Th17 cell culture supernatant treatment. Equally, protease inhibitors with Th17 cell culture treatment blocked the signaling response. This was not replicated by the reagents added to Th17 cell cultures or by IL-17A. Hence, we conclude that an undefined soluble mediator produced by Th17 cells mimics the deleterious effect of PAR-1 activation in vitro. Given the association between pathogenic subsets of Th17 cells and GC resistance, these observations have potential therapeutic relevance for patients with NS.

Th17 cells in renal inflammation and autoimmunity

Th17 cells are a distinct lineage of T-cells. These T-cells express IL-17A and the lineage-defining transcription factor RORγt. Th17 cells have a pivotal, physiological role in host defense against pathogens. These pro-inflammatory T-cells are also key players in autoimmunity and a pathogenic role has been demonstrated in several diseases such as rheumatoid arthritis or psoriasis. Recently, there is evidence that Th17 cells may drive renal inflammation and renal autoimmunity in anti-neutrophil-cytoplasmic-antibody-(ANCA)-vasculitis and systemic lupus erythematosus. The aim of this review is to discuss the possible involvement of Th17 cells in renal autoimmunity and its value for future therapeutic approaches.

The elevated levels of urinary angiotensinogen are correlated with the severity of idiopathic membranous nephropathy

Background

Immunosuppressive treatment will predispose an idiopathic membranous nephropathy (iMN) patient to opportunistic infections. Disease severity is one of the main concerns for making the treatment decision. Urinary angiotensinogen (UAGT) level has been shown highly correlated with intrarenal renin-angiotensin system (RAS) activity and severity of chronic kidney diseases (CKD). We aimed to test the relationship between the UAGT level and the severity of iMN.

Methods

This cross-sectional study included a total of 48 biopsy-proven iMN patients, 46 minimal change disease (MCD) patients, and 44 healthy volunteers. The clinical and laboratory data and urine samples were collected from all subjects before the use of RAS inhibitors. We determined the UAGT levels with a method of enzyme-linked immunosorbent assay.

Results

The UAGT levels were not different between the iMN (277.05 ± 61.25, μg/g.Cr) and MCD patients (244.19 ± 40.24, μg/g.Cr), but both of them were significantly higher than those of healthy controls (6.85 ± 1.10, μg/g.Cr). UAGT levels were correlated negatively with serum albumin (r = − 0.393, p = 0.006) and estimated glomerular filtration rate (eGFR) (r = − 0.352, p = 0.014) and positively with 24-h proteinuria (r = 0.614, p < 0.001) in iMN patients but not in MCD patients. Multivariate linear regression analysis revealed that only proteinuria independently determinate the levels of UAGT (β = 0.649, p < 0.001) in iMN patients.

Conclusions

UAGT levels were correlated negatively with serum albumin and glomerular filtration rate and positively with proteinuria in iMN patients at the onset. This suggests that elevated levels of UAGT are associated with the severity of iMN. The UAGT level may be used as a cofactor for deciding immunosuppressive therapy in iMN patient.

Efficacy and safety of mycophenolate mofetil versus levamisole in frequently relapsing nephrotic syndrome: an open-label randomized controlled trial

Both levamisole and mycophenolate mofetil (MMF) prevent relapses in patients with frequently relapsing nephrotic syndrome; however, their efficacy has not been compared prospectively. This single-center, randomized, open-label trial enrolled 149 children ages 6-18 years with frequently relapsing or steroid-dependent nephrotic syndrome. Participants were randomized in a 1:1 ratio to receive therapy with MMF (750-1000 mg/m² daily) or levamisole (2-2.5 mg/kg on alternate days) for 1 year; prednisolone was discontinued by 2-3 months. In intention-to-treat analyses, the frequency of relapse was similar between participants treated with MMF and levamisole (mean difference -0.29 relapses/patient-year; 95% confidence interval -0.65, 0.08). Relapse rates declined to almost one-third of baseline for both treatment groups. Therapy with MMF was not superior to levamisole in terms of the proportions of participants with sustained remission (40.8% vs. 34.2%), frequent relapses (14.5% vs. 16.4%), or treatment failure, a composite outcome of frequent relapses, steroid resistance, or significant steroid toxicity (15.8% vs. 20.6%). These outcomes were also similar in time to event analyses. Changes in anthropometry and blood pressure were similar between the groups, and the rates of adverse effects were low in both groups. Flow cytometry in 32 participants demonstrated similar proportions of B cells and CD4+, CD8+, T helper (Th)1, Th2, Th17, and T regulatory (Treg) cells during follow-up. Therapy with MMF was not superior to levamisole in the frequency of relapses, likelihood of sustained remission or corticosteroid sparing in children with frequently relapsing or steroid-dependent nephrotic syndrome. Registration CTRI/2012/02/002394.