Synthetic Peptide Antigens to Detect Anti-Nephrin Autoantibodies

NU2025-147

Inventors

• Jing Jin*
• Pan Liu

Short Description

The invention provides a method for detecting anti-nephrin autoantibodies implicated in kidney diseases like minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). This method employs synthetic peptide antigens for use as a clinical diagnostic.

Background

Kidney glomerular diseases such as MCD and FSGS are linked to a circulating "permeability factor," now understood to involve autoantibodies targeting nephrin, a key glomerular protein. Despite growing research into anti-nephrin antibodies, significant challenges persist in their reliable detection. Inconsistencies in methodologies and results have raised concerns about false positives, leading the European Renal Association to call for more advanced and specific detection techniques. Currently, no commercial assays exist for clinical detection of these autoantibodies. Research laboratories typically employ recombinant nephrin proteins as antigens, which are large (>100 kDa), complex to produce consistently, suffer from batch variability, and exhibit low molar density on assay surfaces, thereby limiting sensitivity, reproducibility, and standardization crucial for clinical utility. These issues hinder accurate diagnosis, disease monitoring, and a comprehensive understanding of these autoimmune kidney conditions.

Abstract

Using synthetic peptide arrays, Northwestern researchers mapped reactive epitopes of the nephrin protein in FSGS. Two key epitopes were identified, both 20 amino acids in length, along with shorter core sequences. These peptides can be chemically synthesized and modified, such as with N-terminal biotinylation, for immobilization on solid supports. The assay system then uses anti-human immunoglobulin antibodies conjugated to reporter molecules to detect patient autoantibodies bound to the immobilized peptides. This approach is compatible with standard immunoassay platforms like ELISA, Chemiluminescence Immunoassay (CLIA), and Biolayer Interferometry (BLI), offering improved manufacturing consistency, higher molar density for enhanced sensitivity, and better reproducibility compared to recombinant protein-based assays.

Applications

• Clinical diagnostic for autoimmune kidney diseases – synthetic peptide-based assays offer a reliable, reproducible, and scalable method to detect anti-nephrin autoantibodies
• Research reagent – the novel peptides can be supplied as research reagents to facilitate studies on anti-nephrin autoantibodies

Advantages

• Enhanced assay sensitivity and specificity reduces false-positives and facilitates early diagnosis
• Improved reproducibility and scalability
• Compatibility with standard immunoassay platforms

Publications

Liu, et al. Evaluation of methologies in anti-nephrin autoantibody detection.  Kidney Int. 2025.

IP Status

A provisional patent has been filed.