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

Serum tumour necrosis factor-alpha as a marker of disease activity in children with nephrotic syndrome

Idiopathic nephrotic syndrome (NS) is a common glomerular disease in children throughout the world; however, the exact pathogenesis of the disease remains unknown. Several studies have shown that tumour necrosis factor-alpha (TNF-α), a proinflammatory cytokine, plays a significant role in the pathogenesis of NS. The literature lacks sufficient data to establish the relationship between TNF-α and NS. This prospective study was conducted on children aged 1-14 years diagnosed with idiopathic NS. All enrolled individuals were followed up from disease onset or relapse of NS until remission or at least 42 days with steroid therapy if remission was not achieved. Serum TNF-α levels were measured at presentation and remission or after 42 days of steroid therapy if remission was not achieved. The role of TNF-α levels in response to steroid therapy in NS was also assessed. One hundred and twelve children (68% boys) with idiopathic NS were enrolled. The median age (interquartile range) at enrolment was 58.5 (37-84.7) months, while the median age at symptom onset was 47.5 (24-60.7) months. The median TNF-α level at presentation was 7.5 (3.5-12.1) pg/ml, and that at remission was 5.25 (1.62-8.8) pg/ml. The median TNF-α levels among first-episode NS at presentation were 3.98 pg/ml and 1.88 pg/ml (P = .04) at remission, whereas in steroid-resistant NS, it was 6.59 pg/ml at presentation and 9.02 pg/ml at 42 days (P = .45). There was a significant negative correlation between the duration of steroid therapy and TNF-α levels, with a correlation factor of -0.021 and R2 of 0.154 (P≤.001). Serum TNF-α levels decrease with steroid therapy in children with steroid-sensitive NS, which correlates clinically with the achievement of remission.

Evaluation of immature granulocyte percentage and count in pediatric nephrotic syndrome

OBJECTIVE

The importance of immature granulocytes (IGs) in most infectious and inflammatory diseases has been highlighted. This study aimed to determine the clinical usability and importance of changes in the peripheral complete blood count profile, including IG percentage (IG%) and IG count (IG#), during the relapse and remission phases in pediatric nephrotic syndrome (NS) patients.

METHODS

This retrospective observational study was performed at a tertiary care hospital between February 2020 and August 2022. Demographic characteristics and laboratory parameters were recorded. The IG count and IG% were measured using an automated hematological analyzer.

RESULTS

IG% and IG# were both higher during the relapse phase of NS than during the remission phase (0.29% ± 0.14%, versus 0.23% ± 0.14%, p = 0.037 and 0.027 ± 0.015 × 103/µL, versus 0.018 ± 0.014 × 103/µL, p = 0.005, respectively). The neutrophil to lymphocyte ratio (NLR), platelet (PLT), white blood cell (WBC), and neutrophil counts had a strong positive correlation with IG# (r = 0.397, p < 0.001; r = 0.352, p < 0.001; r = 0.622, p < 0.001; r = 0.660, p < 0.001, respectively). The NLR, PLT, WBC, and neutrophil counts had a strong positive correlation with IG% (r = 0.348, p < 0.001; r = 0.187, p = 0.039; r = 0.303, p = 0.001; r = 0.426, p < 0.001, respectively). Receiver operating characteristic curve analysis showed that IG# had the best AUC value of 0.69 (95% CI: 0.58-0.77; p = 0.001) for the relapse phase of NS with a cutoff value of 0.025 × 103/µL (sensitivity: 81.0%, specificity: 78.1%).

CONCLUSIONS

It is probable that a high level of immature granulocyte count has a positive correlation for NS relapse in pediatric patients. The IG % and IG# can be used together as biomarkers of inflammation in pediatric NS relapse.

Relation between interleukin-13 and annexin-V levels and carotid intima-media thickness in nephrotic syndrome

Background and aim

The aim of the current study is to assess the relation between carotid intima-media thickness (CIMT) measurements, renal Doppler resistive index (RI) and serum levels of interleukin-13 (IL-13) and annexin-V (An-V) in children with idiopathic nephrotic syndrome (INS).

Materials and methods

The present case-control study was conducted on 60 children with INS and 60 age- and sex-matched healthy children. All participants were subjected to evaluation of serum levels of IL-13 and An-V and ultrasound Doppler measurement of CIMT and renal RI.

Results

Patients expressed significantly higher An-V (5.9 ± 2.6 vs. 2.1 ± 0.8 ng/mL, p<0.001) and IL-13 (19.2 ± 7.6 vs. 3.4 ± 1.4 ng/L) levels when compared with healthy counterparts. Moreover, it was shown that patients had significantly higher CIMT (0.49 ± 0.06 vs. 0.35 ± 0.03, p<0.001) as compared to controls. No significant differences were noted between the studied groups regarding right or left RIs. Correlation analysis identified significant direct correlation between serum An-V levels and albumin/creatinine ratio (ACR) (r = 0.55), cholesterol (r = 0.48), triglycerides (r = 0.36), IL-13 (r = 0.92) and CIMT (r = 0.53). Similar correlations could be found between serum IL-13 levels and CIMT measurements and the corresponding parameters.

Conclusions

The present study suggests an association between higher early atherosclerosis expressed as elevated CIMT measurements in children with INS and elevated serum levels of An-V and IL-13.

Metabolomic Analysis of Stephania tetrandra-Astragalus membranaceus Herbal Pair-Improving Nephrotic Syndrome Identifies Activation of IL-13/STAT6 Signaling Pathway

The Stephania tetrandra−Astragalus membranaceus herbal pair (FH) is a classic herbal pair widely used in the treatment of nephrotic syndrome (NS). The effects of Stephania tetrandra (FJ) and Astragalus membranaceus (HQ) on NS have been reported, but the mechanism of their combination on the improvement of NS are still unclear. The NS model was established by injecting adriamycin into the tail vein. FH intervention reduced the levels of serum triglyceride, total cholesterol, interleukin-6 (IL-6), blood urea nitrogen (BUN), urinary protein, and the gene expression levels of aquaporin 2 (AQP2) and arginine vasopressin (AVP) in NS rats. In addition, FH improved kidney injury in NS rats by inhibiting the expression of interleukin 13 (IL-13), phospho-signal transducers, and activators of transcription 6 (p-STAT6), Bax, cleaved-caspase3, while promoting the expression of Bcl-2. By comprehensive comparison of multiple indexes, the effects of FH on lipid metabolism, glomerular filtration rate, and inflammation were superior to that of FJ and HQ. Metabonomic studies showed that, compared with FJ and HQ, FH intervention significantly regulated tricarboxylic acid (TCA) cycle, cysteine and methionine metabolism, and alanine, aspartic acid and glutamic acid metabolism. Pearson correlation analysis showed that succinic acid and L-aspartic acid were negatively correlated with urinary protein, cystatin C (Cys C) and BUN (p < 0.05). In summary, FH could reduce renal injury and improve NS through inhibiting the IL-13/STAT6 signal pathway, regulating endogenous metabolic pathways, such as TCA cycle, and inhibiting the expression of AQP2 and AVP genes. This study provides a comprehensive strategy to reveal the mechanism of FH on the treatment of NS, and also provides a reasonable way to clarify the compatibility of traditional Chinese medicine.

Protocol for an open-label, single-arm, multicentre clinical study to evaluate the efficacy and safety of rituximab in the first episode of paediatric idiopathic nephrotic syndrome

INTRODUCTION

Rituximab (RTX) effectively prevents relapses in patients with complicated steroid-sensitive nephrotic syndrome (SSNS). The 1-year relapse-free survival rate is approximately 30% in children after the first episode of SSNS treated with standardised corticosteroids. Whether the benefits of RTX extend to the first relapse are unknown. The efficacy and safety of RTX in the first episode of paediatric idiopathic nephrotic syndrome (RTXFIRPedINS) trial (NCT04783675) will assess its effect on the risk of subsequent relapse.

METHODS AND ANALYSIS

RTXFIRPedINS is an open-label, single-arm, multicentre trial targeting patients aged 1-18 years with a first episode of SSNS. All patients will receive standardised corticosteroid treatment for 12 weeks. A sample size of 44 patients provides 80% power to detect a 20% increase in the 1-year relapse-free rate, assuming a dropout rate of 10%. After obtaining informed consent and screening, eligible patients will be treated with a single intravenous infusion of 375 mg/m² RTX within 1 week after achieving remission. Trimethoprim-sulfamethoxazole will be administered for 3 months after RTX administration to prevent Pneumocystis carinii infection. The follow-up period will be 1 year. The primary outcome is the 1-year relapse-free survival rate after RTX infusion. The secondary study outcomes are the number of days from the infusion of RTX to the occurrence of the first relapse, 6-month relapse-free survival rate, the B cell recovery time and treatment-related adverse events. Immunological factors will be studied as predictors of response.

ETHICS AND DISSEMINATION

This trial was approved by the Ethics Committee of the Children's Hospital of Fudan University and seven local ethics committees. We will publish our study results in peer-reviewed journals and present them at international scientific meetings.

TRIAL REGISTRATION NUMBER

NCT04783675.