Peptidyl arginine deiminase expression and macrophage polarization following stimulation with citrullinated and malondialdehyde-acetaldehyde modified fibrinogen

Nozima Aripova, Michael J. Duryee, Carlos D. Hunter, Evan M. Ryan, Eric C. Daubach, Spencer Q. Jones, Madison M. Bierman, Austin S. Ragland, Ananya Mitra, Bryant R. England, Debra J. Romberger, Geoffrey M. Thiele, Ted R. Mikuls

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Objective: Post-translational modifications of extracellular matrix proteins such as fibrinogen may lead to tolerance loss and have been implicated in rheumatoid arthritis (RA) pathogenesis. The purpose of this study was to determine whether fibrinogen (FIB) modified with citrulline (CIT), malondialdehyde-acetaldehyde (MAA) or both leads to altered macrophage polarization, peptidyl arginine deiminase (PAD) expression, or production of citrullinated proteins. Methods: PMA-treated U-937 cells (M0 cells) were stimulated with MAA, CIT or MAA-CIT modified FIB. Macrophage (M1/M2) phenotypes were evaluated by flow cytometry, RT-PCR, and ELISA. PAD enzyme expression and protein citrullination was evaluated using RT-PCR and Western Blot. Results: Flow cytometry revealed that M0 macrophages stimulated with FIB-MAA-CIT resulted in mixed M1/M2 phenotypes as demonstrated by cell surface expression and mRNA levels of CD14, CD192, CD163, and CD206 (p < 0.001 vs. others), and the release of IL-18, IP-10, CCL22, and IL-13 (p < 0.001 vs. others). While FIB-MAA treated M0 cells demonstrated a mixed M1/M2 phenotype, cytokine and cell surface markers differed from FIB-MAA-CIT. Finally, M0 cells treated with FIB-CIT demonstrated markers and cytokines consistent with only the M1-like phenotype. Exposure of M0 cells to FIB-MAA-CIT (at 48 h) and FIB-MAA (at 24 h) led to increased mRNA expression and protein expression of PAD2 (p < 0.001) with increased protein citrullination. Conclusion: These findings suggest that MAA-modification and citrullination of FIB, in isolation or combination, yield specific effects on macrophage polarization, PAD expression and citrullination that ultimately may induce inflammatory and fibrotic responses associated with RA.

Original languageEnglish (US)
Article number109010
JournalInternational Immunopharmacology
Volume110
DOIs
StatePublished - Sep 2022

Keywords

  • Citrullination
  • Macrophage
  • Malondialdehyde-acetaldehyde
  • Peptidylarginine deiminase
  • Post-translational modification
  • Rheumatoid arthritis

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Pharmacology

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