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Generation of Distinct Patterns of Rheumatoid Arthritis Autoantigens by Peptidylarginine Deiminase Types 2 and 4 During Perforin‐Induced Cell Damage
Author(s) -
Romero Violeta,
Darrah Erika,
Andrade Felipe
Publication year - 2020
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.41196
Subject(s) - cytotoxic t cell , citrullination , perforin , antigen , granzyme , immunology , citrulline , biology , microbiology and biotechnology , chemistry , cd8 , in vitro , arginine , biochemistry , amino acid
Objective To address the independent roles of peptidylarginine deiminase type 2 ( PAD 2) and PAD 4 in generating rheumatoid arthritis ( RA ) autoantigens by using a system that mimics intracellular citrullination in the RA joint. Methods PAD 2‐ or PAD 4‐expressing 293T cells and mock‐transfected cells were used as targets in cytotoxic assays using lymphokine‐activated killer cells, cytotoxic YT cell granule contents, or purified human perforin. Protein citrullination and autoantigen production were determined by immunoblotting using the anti–modified citrulline–Senshu method and RA sera (n = 30), respectively. Results RA sera recognized at least 3 categories of autoantigens in PAD ‐expressing target cells killed by the cytotoxic lymphocyte granule–induced death pathway. These included: 1) autoantigens targeted in their native form, 2) citrullinated antigens, and 3) antigens cleaved by cytotoxic proteases (e.g., granzymes). Interestingly, although target cells expressing PAD 2 or PAD 4 showed prominent hypercitrullination of a broad range of proteins during cytotoxic granule–induced cell damage, autoantibodies in RA sera targeted only a very limited number of antigens in hypercitrullinated cells. Furthermore, RA sera showed distinct reactivities to autoantigens generated by PAD 2 or PAD 4. Conclusion The cytotoxic granule–induced death pathway has the capacity to modify antigens by inducing hypercitrullination and antigen cleavage in target cells. Interestingly, among a large number of citrullinated proteins generated by PAD 2 and PAD 4 in cells, only a few are likely involved in the production of autoantibodies in RA .