Proteomic Analysis of Complement Proteins in Membranous Nephropathy

Aishwarya Ravindran, Benjamin Madden, M. Cristine Charlesworth, Rishi Sharma, Amit Sethi, Hanna Debiec, Daniel Cattran, Fernando C. Fervenza, Richard J. Smith, Pierre Ronco, Sanjeev Sethi

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Introduction: Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in Caucasian adults. Phospholipase A2 receptor (PLA2R)– and exostosin 1 (EXT1)/exostosin 2 (EXT2)–associated MN represent the most common primary and secondary forms of MN. The complement profile using a proteomics approach has not been studied in these 2 common forms of MN. Methods: We used laser microdissection and mass spectrometry (MS/MS) to dissect glomeruli and identify glomerular complement proteins in PLA2R-associated (n = 7), EXT1/EXT2-associated MN (n = 21), and 11 control cases (time 0 transplant biopsies). Results: MS/MS identified high total spectral counts for PLA2R and EXT1/EXT2 in corresponding cases of PLA2R- and EXT1/EXT2-positive MN. Both PLA2R- and EXT1/EXT2-associated MN had high spectral counts of complement proteins C3, C4, C5, C6, C7, C8, and C9. Complement protein C1 was present in low spectral counts in EXT1/EXT2-associated MN. Regulators of complement activation that were detected in MN included higher spectral counts of FH, FHR-1, FHR-5, clusterin, vitronectin and lower spectral counts of FHR-3, FHR-4, and CD59. Low spectral counts of FB and properdin, key components of the alternative pathway, also were detected. IgG4 and IgG1 were the most abundant IgG subclasses in PLA2R- and EXT1/EXT2-associated MN. Lower spectral counts for C3, C4, and C5 were detected in control cases when compared with MN. Conclusion: Significant complement activation is present in MN as evidenced by large spectral counts of complement proteins from C3- and C4-based pathways, including regulatory proteins of complement pathways. These data suggest that anticomplement drugs may be effective in treatment for MN.

Original languageEnglish (US)
Pages (from-to)618-626
Number of pages9
JournalKidney International Reports
Volume5
Issue number5
DOIs
StatePublished - May 2020

Keywords

  • complement
  • laser microdissection
  • mass spectrometry
  • membranous nephropathy

ASJC Scopus subject areas

  • Ophthalmology
  • Nephrology

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    Ravindran, A., Madden, B., Charlesworth, M. C., Sharma, R., Sethi, A., Debiec, H., Cattran, D., Fervenza, F. C., Smith, R. J., Ronco, P., & Sethi, S. (2020). Proteomic Analysis of Complement Proteins in Membranous Nephropathy. Kidney International Reports, 5(5), 618-626. https://doi.org/10.1016/j.ekir.2020.01.018