AIM: Rapidly expanding manufacture and use of nanomaterials emphasize the requirements for thorough assessment of health outcomes associated with novel applications. Post-translational protein modifications catalyzed by Ca(2+)-dependent peptidylargininedeiminases have been shown to trigger immune responses including autoantibody generation, a hallmark of immune complexes deposition in rheumatoid arthritis. Therefore, the aim of the study was to assess if nanoparticles are able to promote protein citrullination.

MATERIALS and METHODS: Human A549 and THP-1 cells were exposed to silicon dioxide, carbon black or single-walled carbon nanotubes. C57BL/6 mice were exposed to respirable single-walled carbon nanotubes. Protein citrullination, peptidylargininedeiminases activity and target proteins were evaluated.

RESULTS: The studied nanoparticles induced protein citrullination both in cultured human cells and mouse lung tissues. Citrullination occurred via the peptidylargininedeiminase-dependent mechanism. Cytokeratines 7, 8, 18 and plectins were identified as intracellular citrullination targets.

CONCLUSION: Nanoparticle exposure facilitated post-translational citrullination of proteins.