Can microRNA profiles predict corticosteroid responsiveness in childhood nephrotic syndrome? A study protocol.

Introduction: In last few years, several studies have revealed the remarkable stability of extracellular microRNAs (miRNAs) circulating in the blood or excreted in the urine and underscored their key importance as biomarkers of certain diseases. Since miRNA in urinary sediment is relatively stable and easily quantified, it has the potential to be developed as a biomarker for disease diagnosis and monitoring. Identification of serum and urinary levels of certain miRNAs may assist in the diagnosis and assessment of disease activity in patients with nephrotic syndrome (NS). The global expression profile of miRNAs in childhood NS in Indian population remains unknown. Hence, further research is warranted in this area. This study seeks to prospectively evaluate whether a multipronged multiomics approach concentrating on microRNA expression profiles in children with NS vis-a-vis normal healthy children is discriminant enough to predict steroid responsiveness in childhood NS.

Methods and analysis: In this prospective multicentric cohort study, subjects will be recruited from general paediatric and paediatric nephrology outpatient departments (OPDs) in tertiary care level referral hospitals. Age-matched and sex-matched healthy individuals with normal renal function (as assessed by normal serum creatinine and normal ultrasound of kidneys, ureter and bladder) in 1:1 ratio between study and control groups will be recruited from among the healthy siblings of children presenting to the OPDs. Differential microRNA expression profiles in urine and serum samples of children with steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS) with healthy children will be compared in a two-phased manner: a biomarker discovery phase involving pooled samples across SSNS, SRNS and healthy siblings analysed in triplicate using next-generation sequencing, slide microarray and quantitative reverse transcriptase PCR (qRT-PCR) arrays covering human miRNome followed by a validation phase with customised qRT-PCR primers based on the concordance in the discovery phase differential expression profiles and bioinformatics analysis.

Ethics and dissemination: The study is funded after dueInstitutional Ethics Committee (IEC) clearance, and results will be available as open access.