T-lymphocyte-expressing inflammatory cytokines underlie persistence of proteinuria in children with idiopathic nephrotic syndrome

The causal relationship between immune cells and different kidney diseases: A Mendelian randomization study

Studies have suggested that the progress of most kidney diseases from occurrence to course and subsequent related complications are closely related to inflammatory reaction. Increased common leukocytes count in the family (neutrophils, eosinophils, basophils, lymphocytes, etc.) are also involved in the tissue damage of kidney diseases. However, these studies are only traditional observational studies, which cannot prove whether there is a causal relationship between these four kinds of leukocytes count and kidney diseases. We aim to explore the causal relationship between these four kinds of leukocytes count and kidney diseases by Mendelian randomization (MR). Large sample size of the genome-wide association database of four cell traits (neutrophil, basophil, lymphocyte, and eosinophil cell counts) in the leukocyte family were used as exposure variables. The outcome variables were various renal diseases (including chronic renal failure, acute renal failure, hypertensive heart or/and kidney disease, hypertensive renal disease, disorders resulting from impaired renal tubular function, and type 1 diabetes with renal complications). The covariates used in multivariable MR are also four cell traits related to blood cells (neutrophil, basophil, lymphocyte, and eosinophil cell counts). Instrumental variables and single nucleotide polymorphic loci were identified (P < 5 × 10-8. Linkage disequilibrium R2 < 0.001). The causal relationships were studied by inverse variance weighted (IVW), weighted median, and MR-Egger regression. Sensitivity analysis was also performed. In our study, IVW analysis results showed that increased neutrophil cell count was a risk factor for chronic renal failure (OR = 2.0245861, 95% CI = 1.1231207-3.649606, P = 0.01896524), increased basophil cell count was a risk factor for chronic renal failure (OR = 3.975935, 95% CI = 1.4871198-10.62998, P = 0.005942755). Basophil cell count was not a risk factor for acute renal failure (OR = 1.160434, 95% CI = 0.9455132-1.424207, P = 0.15448828). Increased basophil cell count was a protective factor for hypertensive heart and/or renal disease (OR = 0.7716065, 95% CI = 0.6484979-0.9180856, P = 0.003458707). Increased basophil cell count was a risk factor for disorders resulting from impaired renal tubular function (OR = 1.648131, 95% CI = 1.010116-2.689133, P = 0.04546835). Increased lymphocyte cell count was a risk factor for hypertensive renal disease (OR = 1.372961, 95% CI = 1.0189772-1.849915, P = 0.03719874). Increased eosinophil cell count was a risk factor for type 1 diabetes with renal complications (OR = 1.516454, 95% CI = 1.1826453-1.944482, P = 0.001028964). Macrophage inflammatory protein 1b levels was a protective factor for renal failure (OR = 0.9381862, 95% CI = 0.8860402-0.9934013, P = 0.02874872). After multivariable MR was used to correct covariates (neutrophil, basophil, and lymphocyte cell counts), the correlation effect between increased eosinophil cell counts and type 1 diabetes with renal complications was still statistically significant (P = 0.02201152). After adjusting covariates (neutrophil, basophil, and eosinophil cell counts) with multivariable MR, the correlation effect between increased lymphocyte cell counts and hypertensive renal disease was still statistically significant (P = 0.02050226). This study shows that increased basophils can increase the relative risk of chronic renal failure and renal tubular dysfunction, and reduce the risk of hypertensive heart disease and/or hypertensive nephropathy, while increased basophil cell count will not increase the relative risk of acute renal failure, increased neutrophil cell count can increase the risk of chronic renal failure, increased lymphocyte cell count can increase the relative risk of hypertensive nephropathy, and increased eosinophil cell count can increase the relative risk of type 1 diabetes with renal complications. Macrophage inflammatory protein 1b levels was a protective factor for renal failure.

CD8 T Cell-Derived Exosomal miR-186-5p Elicits Renal Inflammation via Activating Tubular TLR7/8 Signal Axis

T cells play an important role in the development of focal segmental glomerulosclerosis (FSGS). The mechanism underlying such T cell-based kidney disease, however, remains elusive. Here the authors report that activated CD8 T cells elicit renal inflammation and tissue injury via releasing miR-186-5p-enriched exosomes. Continuing the cohort study identifying the correlation of plasma level of miR-186-5p with proteinuria in FSGS patients, it is demonstrated that circulating miR-186-5p is mainly derived from activated CD8 T cell exosomes. Renal miR-186-5p, which is markedly increased in FSGS patients and mice with adriamycin-induced renal injury, is mainly delivered by CD8 T cell exosomes. Depleting miR-186-5p strongly attenuates adriamycin-induced mouse renal injury. Supporting the function of exosomal miR-186-5p as a key circulating pathogenic factor, intravenous injection of miR-186-5p or miR-186-5p-containing T cell exosomes results in mouse renal inflammation and tissue injury. Tracing the injected T cell exosomes shows their preferential distribution in mouse renal tubules, not glomerulus. Mechanistically, miR-186-5p directly activates renal tubular TLR7/8 signal and initiates tubular cell apoptosis. Mutating the TLR7-binding sequence on miR-186-5p or deleting mouse TLR7 largely abolishes renal tubular injuries induced by miR-186-5p or adriamycin. These findings reveal a causative role of exosomal miR-186-5p in T cell-mediated renal dysfunction.

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.

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.

Beneficial effects of procyanidin B2 on adriamycin-induced nephrotic syndrome mice: the multi-action mechanism for ameliorating glomerular permselectivity injury

Despite considerable advances in prevention, diagnosis, and therapy, nephrotic syndrome (NS) remains a significant cause of high morbidity and mortality globally. As a result, there is an urgent need to identify novel effective preventative and therapeutic agents for NS. NS is implicated in glomerular permselectivity injury, which can be attributed to oxidative distress, inflammation, lipid nephrotoxicity, podocyte apoptosis, autophagy dysfunction, and slit diaphragm (SLD) dysfunction. In addition to its well-documented antioxidant potency, procyanidin B2 (PB2) may exhibit pleiotropic effects by targeting various canonical signaling events, such as NF-κB, PPARs, PI3K/Akt, mTOR, and the caspase family. As a result, PB2 may be a promising therapeutic target against NS. To test this hypothesis, we established an Adriamycin (ADR)-induced NS mouse model to evaluate the pleiotropic renoprotective effects of PB2 on NS. Here, we demonstrated that PB2 improves podocyte injury via inhibition of NOX4/ROS and Hsp90/NF-κB to exhibit antioxidant and anti-inflammatory potency, respectively. We also show that PB2 indirectly activates the PI3K/Akt axis by regulating SLD protein levels, resulting in normalized podocyte apoptosis and autophagy function. Further, loss of albumin (ALB) induces lipid nephrotoxicity, which we found to be alleviated by PB2 via activation of PPARα/β-mediated lipid homeostasis and the cholesterol efflux axis. Interestingly, our results also suggested that PB2 reduces electrolyte abnormalities and edema. In addition, PB2 may contribute protective effects against trace element dys-homeostasis, which, through alleviating serum ALB loss, leads to a protective effect on glomerular permselectivity injury. Taken together, our results reveal that the identified mechanisms of PB2 on NS are multifactorial and involve inhibition of oxidative distress and inflammatory responses, as well as improvements in podocyte apoptosis and autophagy dysfunction, amelioration of lipid nephrotoxicity, and modulation of electrolyte abnormalities and edema. Thus, we provide a theoretical basis for the clinical application of PB2 against NS.

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.

Idiopathic Nephrotic Syndrome in Pediatrics: An Up-to-date

BACKGROUND

Idiopathic or Primary Nephrotic Syndrome (INS) is a common glomerular disease in pediatric population, characterized by proteinuria, edema and hypoalbuminemia with variable findings in renal histopathology.

OBJECTIVE

This review aims to summarize current data on the etiopathogenesis diagnosis, protocols of treatment and potential therapeutic advances in INS.

METHODS

This narrative review searched for articles on histopathology, physiopathology, genetic causes, diagnosis and treatment of INS in pediatric patients. The databases evaluated were PubMed and Scopus.

RESULTS

INS is caused by an alteration in the permeability of the glomerular filtration barrier with unknown etiology. There are several gaps in the etiopathogenesis, response to treatment and clinical course of INS that justify further investigation. Novel advances include the recent understanding of the role of podocytes in INS and the identification of genes associated with the disease. The role of immune system cells and molecules has also been investigated. The diagnosis relies on clinical findings, laboratory exams and renal histology for selected cases. The treatment is primarily based on steroids administration. In case of failure, other medications should be tried. Recent studies have also searched for novel biomarkers for diagnosis and alternative therapeutic approaches.

CONCLUSION

The therapeutic response to corticosteroids still remains the main predictive factor for the prognosis of the disease. Genetic and pharmacogenomics tools may allow the identification of cases not responsive to immunosuppressive medications.

Role of Arachidonic Acid and Its Metabolites in the Biological and Clinical Manifestations of Idiopathic Nephrotic Syndrome

Studies concerning the role of arachidonic acid (AA) and its metabolites in kidney disease are scarce, and this applies in particular to idiopathic nephrotic syndrome (INS). INS is one of the most frequent glomerular diseases in childhood; it is characterized by T-lymphocyte dysfunction, alterations of pro- and anti-coagulant factor levels, and increased platelet count and aggregation, leading to thrombophilia. AA and its metabolites are involved in several biological processes. Herein, we describe the main fields where they may play a significant role, particularly as it pertains to their effects on the kidney and the mechanisms underlying INS. AA and its metabolites influence cell membrane fluidity and permeability, modulate platelet activity and coagulation, regulate lymphocyte activity and inflammation, preserve the permeability of the glomerular barrier, influence podocyte physiology, and play a role in renal fibrosis. We also provide suggestions regarding dietary measures that are able to prevent an imbalance between arachidonic acid and its parental compound linoleic acid, in order to counteract the inflammatory state which characterizes numerous kidney diseases. On this basis, studies of AA in kidney disease appear as an important field to explore, with possible relevant results at the biological, dietary, and pharmacological level, in the final perspective for AA to modulate INS clinical manifestations.

Plasma Cytokine Profiling to Predict Steroid Resistance in Pediatric Nephrotic Syndrome

Introduction

Glucocorticoids (GCs) are the primary treatment for nephrotic syndrome (NS), although ∼10% to 20% of children develop steroid-resistant NS (SRNS). Unfortunately, there are no validated biomarkers able to predict SRNS at initial disease presentation. We hypothesized that a plasma cytokine panel could predict SRNS at disease presentation, and identify potential pathways regulating SRNS pathogenesis.

Methods

Paired plasma samples were collected from 26 children with steroid-sensitive NS (SSNS) and 14 with SRNS at NS presentation and after ∼7 weeks of GC therapy, when SSNS versus SRNS was clinically determined. Plasma cytokine profiling was performed with a panel of 27 cytokines.

Results

We identified 13 cytokines significantly different in Pretreatment SSNS versus SRNS samples. Statistical modeling identified a cytokine panel (interleukin [IL]-7, IL-9, monocyte chemoattractant protein–1 [MCP-1]) able to discriminate between SSNS and SRNS at disease presentation (receiver operating characteristic [ROC] value = 0.846; sensitivity = 0.643; specificity = 0.846). Furthermore, GC treatment resulted in significant decreases in plasma interferon-γ (IFN-γ), tumor necrosis factor–α (TNF-α), IL-7, IL-13, and IL-5 in both SSNS and SRNS patients.

Conclusions

These studies suggest that initial GC treatment of NS reduces the plasma cytokines secreted by both CD4⁺ T_H1 cells and T_H2 cells, as well as CD8⁺ T cells. Importantly, a panel of 3 cytokines (IL-7, IL-9, and MCP-1) was able to predict SRNS prior to GC treatment at disease presentation. Although these findings will benefit from validation in a larger cohort, the ability to identify SRNS at disease presentation could greatly benefit patients by enabling both avoidance of unnecessary GC-induced toxicity and earlier transition to more effective alternative treatments.

Salivary Cytokines in Children with Nephrotic Syndrome versus Healthy Children: A Comparative Study

Background: The aims of this study were to compare salivary cytokines and total protein between children with nephrotic syndrome (NS) and healthy children, and to examine whether saliva parameters can differentiate between steroid sensitivity and resistance and between disease remission and relapse. Methods: Twenty-seven children with nephrotic syndrome were classified according to steroid sensitivity and resistance, and disease remission and relapse. Twenty healthy children served as controls. Whole saliva samples were collected from all the participants. Urine and blood tests done on the same day as the saliva collection were recorded. Salivary total protein was quantified using bicinchoninic acid and IFNγ, IL-4, IL-8, IL-6, and IL1β levels using ELISA. Results: The mean ages of the nephrotic syndrome and control groups were 11.3 ± 2.4 and 9 ± 4.2, respectively. Compared to the control group, for the nephrotic syndrome group, total salivary protein was significantly lower, as were the levels of all the cytokines examined except IFNγ. Statistically significant differences were not found in any of the salivary markers examined between the children with nephrotic syndrome who were treatment sensitive (n = 19) and resistant (n = 8). Protein and IL-8 salivary levels were lower in the active (n = 7) than in the remission (n = 20) group. Conclusions: Salivary parameters distinguished children with nephrotic syndrome in relapse from healthy children. This may be due to decreased salivary protein excretion, which reflects decreased plasma levels, consequent to proteinuria. Accordingly, salivary markers may be developed as a diagnostic or screening tool for NS activity.

Persistent Abnormalities of Fatty Acids Profile in Children With Idiopathic Nephrotic Syndrome in Stable Remission

Steroid-sensitive nephrotic syndrome is an immunological disorder mediated by still poorly defined circulating factor(s) that target the podocyte and damage the filtration barrier. Fatty acids (FA) have several biological roles and, in particular, are strictly involved in cell to cell communication, inflammatory processes and regulation of lymphocyte pools. Studies of FAs during INS have been mainly focused on biochemical changes during the phase of proteinuria; while no information is available about FA profile in patients with idiopathic nephrotic syndrome (INS) on stable remission. Aim of this study is to assess differences in blood FA profile between pediatric patients with INS during the phase of stable remission. Blood fatty acid profile of 47 pediatric patients on stable remission and 47 matched healthy controls were evaluated with gas chromatography. Patients with INS on stable remission had significantly higher levels of PUFA and omega-6 than controls (40.17 vs. 37.91% and 36.95 vs. 34.79%), lower levels of SFA and MUFA. Considering the single fatty acids, levels of omega-6 18:2n6 linoleic acid and omega-6 20:4n6 arachidonic acid were significantly higher in patients with INS than in controls (23.01 vs. 21.55%, p-value 0.003 and 10.37 vs. 9.65%, p-value 0.01). Moreover, patients with INS showed lower levels of SFA 14:0 (0.74 vs. 0.92%) and 18:0 (10.74 vs. 11.74%) and MUFA 18:1n9 oleic acid (18.50 vs. 19.83%). To the best of our knowledge this is the first study assessing FAs profile in children with INS in stable remission. In a population of 47 patients, we were able to demonstrate a higher blood level of linoleic and arachidonic acid, and consequently of omega-6 and PUFA, compared to controls. Persistently higher than normal levels of either linoleic or arachidonic acid, could be viewed as candidate biomarker for a state of risk of relapse in children with idiopathic nephrotic syndrome.

Evidence for a role of angiotensin converting enzyme 2 in proteinuria of idiopathic nephrotic syndrome

Introduction: Renin angiotensin system (RAS) plays a role in idiopathic nephrotic syndrome (INS). Most studies investigated only the classical RAS axis. Therefore, the aims of the present study were to evaluate urinary levels of RAS molecules related to classical and to counter-regulatory axes in pediatric patients with INS, to compare the measurements with levels in healthy controls and to search for associations with inflammatory molecules, proteinuria and disease treatment. Subjects and methods: This cross-sectional study included 31 patients with INS and 19 healthy controls, matched for age and sex. Patients and controls were submitted to urine collection for measurement of RAS molecules [Ang II, Ang-(1-7), ACE and ACE2] by enzyme immunoassay and cytokines by Cytometric Bead Array. Findings in INS patients were compared according to proteinuria: absent (<150 mg/dl, n = 15) and present (≥150 mg/dl, n = 16). Results: In comparison to controls, INS patients had increased Ang II, Ang-(1-7) and ACE, levels while ACE2 was reduced. INS patients with proteinuria had lower levels of ACE2 than those without proteinuria. ACE2 levels were negatively correlated with 24-h-proteinuria. Urinary concentrations of MCP-1/CCL2 were significantly higher in INS patients, positively correlated with Ang II and negatively with Ang-(1-7). ACE2 concentrations were negatively correlated with IP-10/CXCL-10 levels, which, in turn, were positively correlated with 24-h-proteinuria. Conclusion: INS patients exhibited changes in RAS molecules and in chemokines. Proteinuria was associated with low levels of ACE2 and high levels of inflammatory molecules.

Pediatric Patients With Steroid-Sensitive Nephrotic Syndrome Have Higher Expression of T Regulatory Lymphocytes in Comparison to Steroid-Resistant Disease

Background and Aim: Idiopathic nephrotic syndrome (INS) is classified according to the response to drug therapy in steroid-sensitive (SS), steroid-dependent (SD), and steroid-resistant (SR) categories. Previous studies showed changes in inflammatory activity of subpopulations of lymphocytes in INS. This study aimed to compare SS and SR patients in regard to subpopulations of leukocytes, profile of regulatory lymphocytes, and migratory activity of lymphocyte subpopulations. Results obtained in INS patients were also compared to age and sex-matched healthy controls. Methods: This is a cross-sectional study including SS patients (n = 30), SR patients (n = 14), and controls (n = 10). Peripheral blood samples were withdrawn for ex-vivo leukocyte flow cytometry analysis. Results: Percentage of B-lymphocytes and natural killer (NK) cells were significantly reduced in SR patients when compared to controls, while the percentage of NKT cells were decreased in SS patients in comparison to controls. Percentages of CD4⁺ expressing FoxP3 and CTLA4 were significantly higher in SS patients in comparison to SR patients and controls. The expression of integrin CD18 on the surface of T lymphocytes (CD3⁺) was reduced in SS patients if compared to controls. Conclusion: This study found that SS INS patients have higher levels of regulatory T-lymphocytes and lower expression of adhesion molecules than SR patients.

Renal Tubular Complement 3 Deposition in Children with Primary Nephrotic Syndrome

Background

This study aimed to investigate the clinical significance of complement 3 (C3) deposition in renal tubules of children with primary nephrotic syndrome (PNS).

Methods

The clinical and pathological characteristics of PNS were retrospectively reviewed in 99 PNS pediatric patients, who were divided into the C3 deposition and the non-C3 deposition groups.

Results

A total of 39 patients (39.39%) had renal tubule C3 deposition. In the C3 deposition group, the ratios of urine N-acetylglucosaminidase/creatinine (UNAG/Cr), urine β2 microglobulin/creatinine (Uβ2MG/Cr), and urine transferrin/creatinine (UTRF/Cr) were significantly higher than those of the non-C3 deposition group. The patients of the C3 deposition group had lower serum total protein and albumin, higher cholesterol and D-dimer (DD), lower proportion of CD3+CD8+ cells, and higher proportion of CD19+CD23+ cells. The number of the patients with interstitial fibrosis, renal cell vacuolar degeneration, renal tubular immunoglobulin deposition, and severe tubulointerstitial injury in the C3 deposition group was higher than that of the non-C3 deposition group. The C3 deposition intensity was positively correlated with the number of recurrences.

Conclusion

PNS pediatric patients with C3 deposition in renal tubules have more severe disease condition, tubulointerstitial injury, and recurrence suggesting a worse long-term prognosis.