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 6

PTPN22 regulates the Th2/Th17 cytokine profile by suppressing citrullination.

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PTPN22 regulates the Th2/Th17 cytokine profile by suppressing citrullina...
(A and B) PBMCs from 9 at-risk individuals were stimulated with anti-CD3 in the presence or absence of Cl-amidine (Cl-am, 50 μM). The level of citrullinated histone H3 (cit-H3) and total histone H3 (H3) was analyzed by Western blotting (A). Each bracket represents one donor. The cit-H3/H3 density ratios from all donors are shown to the right. The levels of indicated cytokines are shown in B. (C) Jurkat cells expressing (+) or not expressing (–) a doxycycline-inducible PAD2 were treated with doxycycline (50 μM) for 12 hours. The transcript levels of indicated genes from 1 of 3 independent experiments are shown. (D and E) Control PBMCs were transfected with an empty vector (–) or a vector expressing PAD2 or PAD4 and then stimulated with anti-CD3. The levels of PAD2, PAD4, cit-H3, and H3 were measured by Western blotting (D). Representative blots from 6 independent experiments and normalized density of PAD2, PAD4, and cit-H3 are shown. The levels of indicated cytokines in the PBMCs are shown in E. Statistical analysis was performed with paired Student’s 2-tailed t test (A and B) or 1-way ANOVA using empty vector–transfected groups as controls (D and E). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.