A molecular signature of preclinical rheumatoid arthritis triggered by dysregulated PTPN22
Hui-Hsin Chang, Guang-Yaw Liu, Nishant Dwivedi, Bo Sun, Yuko Okamoto, Jennifer D. Kinslow, Kevin D. Deane, M. Kristen Demoruelle, Jill M. Norris, Paul R. Thompson, Jeffrey A. Sparks, Deepak A. Rao, Elizabeth W. Karlson, Hui-Chih Hung, V. Michael Holers, I-Cheng Ho
Hui-Hsin Chang, Guang-Yaw Liu, Nishant Dwivedi, Bo Sun, Yuko Okamoto, Jennifer D. Kinslow, Kevin D. Deane, M. Kristen Demoruelle, Jill M. Norris, Paul R. Thompson, Jeffrey A. Sparks, Deepak A. Rao, Elizabeth W. Karlson, Hui-Chih Hung, V. Michael Holers, I-Cheng Ho
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Research Article

A molecular signature of preclinical rheumatoid arthritis triggered by dysregulated PTPN22

Abstract

A unique feature of rheumatoid arthritis (RA) is the presence of anti-citrullinated protein antibodies (ACPA). Several risk factors for RA are known to increase the expression or activity of peptidyl arginine deiminases (PADs), which catalyze citrullination and, when dysregulated, can result in hypercitrullination. However, the consequence of hypercitrullination is unknown and the function of each PAD has yet to be defined. Th cells of RA patients are hypoglycolytic and hyperproliferative due to impaired expression of PFKFB3 and ATM, respectively. Here, we report that these features are also observed in peripheral blood mononuclear cells (PBMCs) from healthy at-risk individuals (ARIs). PBMCs of ARIs are also hypercitrullinated and produce more IL-2 and Th17 cytokines but fewer Th2 cytokines. These abnormal features are due to impaired induction of PTPN22, a phosphatase that also suppresses citrullination independently of its phosphatase activity. Attenuated phosphatase activity of PTPN22 results in aberrant expression of IL-2, ATM, and PFKFB3, whereas diminished nonphosphatase activity of PTPN22 leads to hypercitrullination mediated by PADs. PAD2- or PAD4-mediated hypercitrullination reduces the expression of Th2 cytokines. By contrast, only PAD2-mediated hypercitrullination can increase the expression of Th17 cytokines. Taken together, our data depict a molecular signature of preclinical RA that is triggered by impaired induction of PTPN22.

Authors

Hui-Hsin Chang, Guang-Yaw Liu, Nishant Dwivedi, Bo Sun, Yuko Okamoto, Jennifer D. Kinslow, Kevin D. Deane, M. Kristen Demoruelle, Jill M. Norris, Paul R. Thompson, Jeffrey A. Sparks, Deepak A. Rao, Elizabeth W. Karlson, Hui-Chih Hung, V. Michael Holers, I-Cheng Ho

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Figure 5

Phosphatase and nonphosphatase activities of PTPN22.

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Phosphatase and nonphosphatase activities of PTPN22. (A) The levels of c...
(A) The levels of cytokines and genes in PBMCs shown in Figure 4 were plotted against the fold induction of PTPN22 shown in the right panel of Figure 3F. Statistical analysis was performed with Spearman’s correlation test. (B and C) PBMCs from at-risk individuals were transfected with plasmid vector expressing PTPN22, W620-PTPN22, CD-PTPN22, or the empty vector (–), and then stimulated with anti-CD3 for 24 hours. The levels of PTPN22, citrullinated histone H3 (cit-H3), and total histone H3 (H3) in transfected/stimulated cells were quantified by Western blotting (B). Representative blots of 6 independent experiments are shown. The density of PTPN22 and cit-H3 was quantified with densitometry and normalized against that of H3. The normalized levels of PTPN22 and cit-H3 are shown. The expression of indicated cytokines and genes was measured with ELISA or real-time PCR (C). The concentration of lactate in supernatant was quantified with a colorimetric assay (C). The data values from the same donors were connected with lines. Statistical analysis for B and C was performed with 1-way ANOVA followed by multiple comparison tests using the empty vector–transfected groups as controls. *P < 0.05; **P < 0.01; ***P < 0.001.