Seasonal variation in first episode of childhood idiopathic steroid-sensitive nephrotic syndrome and adult minimal change nephrotic syndrome

Incidence of idiopathic nephrotic syndrome during the Covid-19 pandemic in the Paris area (France) and in the Netherlands

BACKGROUND

The aetiology of idiopathic nephrotic syndrome (INS) remains partially unknown. Viral infections have been associated with INS onset. Since we observed fewer first onset INS cases during the Covid-19 pandemic, we hypothesised that lower INS incidence was the result of lockdown measures. Therefore, the aim of this study was to evaluate the incidence of childhood INS before and during the COVID-19 pandemic in two independent European INS cohorts.

METHODS

Children with new INS in the Netherlands (2018-2021) and Paris area (2018-2021) were included. We estimated incidences using census data for each region. Incidences were compared using two proportion Z-tests.

RESULTS

A total of 128 and 324 cases of first onset INS were reported in the Netherlands and Paris area, respectively, corresponding to an annual incidence of 1.21 and 2.58 per 100,000 children/year. Boys and young children (< 7 years) were more frequently affected. Incidence before and during the pandemic did not differ. When schools were closed, incidence was lower in both regions: 0.53 vs. 1.31 (p = 0.017) in the Netherlands and 0.94 vs. 2.63 (p = 0.049) in the Paris area. During peaks of hospital admissions for Covid-19, no cases were reported in the Netherlands or Paris area.

CONCLUSIONS

Incidence of INS before and during the Covid-19 pandemic was not different, but when schools were closed during lockdown, incidence was significantly lower. Interestingly, incidences of other respiratory viral infections were also reduced as was air pollution. Together, these results argue for a link between INS onset and viral infections and/or environmental factors. A higher resolution version of the Graphical abstract is available as Supplementary information.

Seasonal variations in renal biopsy numbers and primary glomerular disease features based on the Japan renal biopsy registry

We analyzed the seasonal variations in the number of renal biopsies and clinical characteristics of primary glomerular disease in Japan using the Japan Renal Biopsy Registry (J-RBR). We retrospectively collected clinical and pathological data of patients with primary glomerular disease who were registered in the J-RBR between 2007 and 2018. Immunoglobulin A nephropathy (IgAN), minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN), and postinfectious acute glomerulonephritis (PIAGN) constituted the four major glomerular disorders included in this study (total, 13,989; IgAN, 9121; MCNS, 2298; MN, 2447; and PIAGN, 123). The number of patients with IgAN or MCNS was higher during summer. However, no overt seasonal variations were observed in patients with MN or PIAGN. Subgroup analyses suggested that in the patients with IgAN, more renal biopsies of severe cases were performed during winter, probably owing to age and blood pressure. Furthermore, more renal biopsies of severe cases were performed during spring and winter in patients with MCNS even after adjusting for the abovementioned host factors. This study suggests that seasonal factors influence the decision to perform renal biopsy as well as the pathogenesis of primary glomerular disease. Thus, our findings may provide important insights regarding the pathophysiology of primary glomerular disease.

Epidemiology of idiopathic nephrotic syndrome in children: endemic or epidemic?

BACKGROUND

The etiology of idiopathic nephrotic syndrome (INS) remains partially unknown. Viral infections have been reported to be associated with INS onset and relapse. The aim of this study was to describe the epidemiology of a population-based cohort of children with INS and propose a spatiotemporal analysis.

METHODS

All children aged 6 months to 15 years with INS onset between December 2007 and May 2010 and living in the Paris area were included in a prospective multicenter study. Demographic and clinical features at diagnosis and 2 years were collected.

RESULTS

INS was diagnosed in 188 children, 93 % of whom were steroid sensitive. Annual incidence was 3.35/100,000 children. Standardized incidence ratio (SIR) was higher in one of the eight counties: Seine-Saint-Denis, with SIR 1.43 [95 % confidence interval (CI) 1.02-1.95]. A spatial cluster was further identified with higher SIR 1.36 (95 % CI 1.09-1.67). Temporal analysis within this overincidence area showed seasonal variation, with a peak during the winter period (p <0.01). In addition, partition of the Paris area into quintiles of the population showed that the average delay of occurrence, with regard to the first study case, followed a longitudinal progression (p <0.0001).

CONCLUSION

The clustering of cases, the seasonal variation within this particular area, and the progression over the Paris area altogether suggest that INS may occur on an epidemic mode.

Overall condition improvement in a rat model of nephrotic syndrome treated with CellCept nanoliposomes

Purpose To investigate the effect of CellCept nanoliposomes on Adriamycin-induced nephrotic syndrome in rats. Methods To model nephrotic syndrome, rats were injected with 6.5 mg/kg of Adriamycin in the tail vein. The rats were randomly divided into three groups, including a control group, a free mycophenolate mofetil (MMF)-treated group, and a liposome-encapsulated MMF-treated group. Five weeks after the Adriamycin treatment, the free MMF-treated group received CellCept while the liposome-encapsulated MMF-treated group received the CellCept nanoliposomes for 2 weeks. The general condition of the animals was observed, which included urine volume over 24 h, urine protein levels, and serum biochemical indexes. Renal morphology was also observed. Results The level of urine protein over 24 h was increased in the control group, while plasma albumin (ALB) was decreased. The total cholesterol (TC) and triacylglycerol (TG) levels increased significantly (P < 0.05, P < 0.01). The pathological examination of the kidneys showed some abnormalities. In contrast, these parameters were improved significantly in the free mycophenolate mofetil (MMF)-treated and liposome-contained mycophenolate mofetil (MMF)-treated groups. Conclusion The CellCept nanoliposomes have a good therapeutic effect on Adriamycin-induced nephrotic syndrome in rats.