The Importance of Sphingomyelin Phosphodiesterase Acid-Like 3b (SMPDL-3b) Levels in Kidney Biopsy Specimens of Children With Nephrotic Syndrome

Abstract

Objective

It remains unclear whether the low amount of SMPDL-3b required for rituximab binding is the cause of treatment resistance in patients with treatment-resistant nephrotic syndrome with advanced podocyte injury. Given the limited number of studies on the relationship between rituximab and SMPDL-3b, this study was conducted to assess whether SMPDL-3b levels in pretreatment renal biopsy specimens can be used to predict the clinical effectiveness of immunosuppressive drugs, especially rituximab, in children with nephrotic syndrome.

Methods

Kidney biopsy specimens from 44 patients diagnosed with idiopatic nephrotic syndrome were analyzed using immunohistochemical staining with an anti-SMPDL-3b antibody and real-time polymerase chain reaction (PCR) for SMPDL-3b mRNA expression.

Results

We showed that SMPDL-3b mRNA expression and anti-SMPDL-3b antibody staining did not differ significantly between the patient groups with different responses to immunosuppressive therapies.

Conclusion

Our results suggest that SMPDL-3b may actually be an indicator of disease progression rather than a marker for predicting response to a particular immunosuppressive agent.

Keywords:

• Nephrotic syndrome
• rituximab
• SMPDL-3b
• chronic kidney disease

Acknowledgement

A part of this study (Do sphingomyelin phosphodiesterase acid-like 3b (smpdl-3b) levels in kidney biopsy specimens predict response to immunosuppressive therapy in children with nephrotic syndrome?) was presented in 54 th Annual ESPN Meeting, Ljubljana, Slovenia, 2022. It could be seen in abstracts of the 54 th Annual ESPN Meeting, Pediatr Nephrol (2022).

Authors’ contributions

İ.G. and S.Y designed the study, İ.G. and M.K. drafted article and performed data analysis, M.K. carried out the experiments, generated the figures, N.Y and G.G. analyzed kidney biopsy materalias, H.Ş. analyzed the sequencing data, T.B. drafted and revised the article. All authors approved the final version of the manuscript.

Ethical approval

All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee at which the studies were conducted (IRB approval number 1/2020) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This project was supported by the Scientific Research Projects Unit of Pamukkale University, Project No. 2020TIPF018.