A missense single-nucleotide polymorphism in the PTPN22 gene causing an R620W substitution in the PTPN22 protein is one of the strongest genetic risk factors for rheumatoid arthritis. No consensus model has yet emerged on how PTPN22 increases risk of rheumatoid arthritis. As PTPN22 is a negative regulator of signaling through the T cell receptor, most studies to date have focused on the effect of the polymorphism on adaptive immune cell signaling. Here we wish to explore the concept that PTPN22-W620 impinges on the pathogenesis of rheumatoid arthritis through an action on myeloid cell signaling as well. Recent studies from our laboratory revealed a novel function of PTPN22 as a promoter of type 1 interferon release after engagement of myeloid cell toll-like receptors. Within this pathway, rheumatoid arthritis- predisposing PTPN22-W620 behaves as a loss-of-function variant, and macrophages and dendritic cells expressing PTPN22-W620 display a defect in toll-like receptor-induced type 1 interferon production. Type 1 interferon production by myeloid cells triggers several immunosuppressive mechanisms that protect from rheumatoid arthritis in mouse models. These include IL-27-mediated inhibition of arthritogenic Th17 cell differentiation and IL-1Ra-mediated suppression of inflammation in the rheumatoid joint. Here we hypothesize that loss of function of PTPN22 in dendritic cells and macrophages predisposes to rheumatoid arthritis by reducing type 1 interferon-dependent immunosuppressive mechanism. We will test our hypothesis by exploring whether loss of function of PTPN22 promotes myeloid cell-dependent differentiation of arthritogenic Th17 cells (Aim 1) and IL-1 mediated joint inflammation (Aim 2).
In Aim 3 we will assess whether loss-of-function of PTPN22 or carriage of PTPN22-W620 impairs the immunoregulatory ability of human myeloid cells. By defining immunological mechanisms that are defective in carriers of the PTPN22-W620 variant, our study will suggest new strategies for personalized therapy of rheumatoid arthritis in genetically predisposed individuals.

Public Health Relevance

Variations in several rheumatoid arthritis genes are responsible for arthritis recurrence in families and differences in disease course among individuals. The objective of this grant is to elucidate a novel mechanism of action of one of the most potent human arthritis genes called PTPN22. Our goal is to identify anomalies of PTPN22-regulated immune functions that increase risk of disease and thus can be targeted by new personalized therapies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI070544-09
Application #
9206975
Study Section
Hypersensitivity, Autoimmune, and Immune-mediated Diseases Study Section (HAI)
Program Officer
Peyman, John A
Project Start
2016-07-06
Project End
2020-01-31
Budget Start
2017-02-01
Budget End
2018-01-31
Support Year
9
Fiscal Year
2017
Total Cost
$348,750
Indirect Cost
$123,750
Name
University of California San Diego
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Stanford, Stephanie M; Bottini, Nunzio (2017) Targeting Tyrosine Phosphatases: Time to End the Stigma. Trends Pharmacol Sci 38:524-540
Doody, Karen M; Bottini, Nunzio (2016) Chondrocyte clocks make cartilage time-sensitive material. J Clin Invest 126:38-9
Stanford, Stephanie M; Aleman Muench, German R; Bartok, Beatrix et al. (2016) TGF? responsive tyrosine phosphatase promotes rheumatoid synovial fibroblast invasiveness. Ann Rheum Dis 75:295-302
Fraser, Heather I; Howlett, Sarah; Clark, Jan et al. (2015) Ptpn22 and Cd2 Variations Are Associated with Altered Protein Expression and Susceptibility to Type 1 Diabetes in Nonobese Diabetic Mice. J Immunol 195:4841-52
Stanford, Stephanie M; Bottini, Nunzio (2014) PTPN22: the archetypal non-HLA autoimmunity gene. Nat Rev Rheumatol 10:602-11
Fousteri, G; Jofra, T; Debernardis, I et al. (2014) The protein tyrosine phosphatase PTPN22 controls forkhead box protein 3 T regulatory cell induction but is dispensable for T helper type 1 cell polarization. Clin Exp Immunol 178:178-89
Wu, Dennis J; Zhou, Wenbo; Enouz, Sarah et al. (2014) Autoimmunity-associated LYP-W620 does not impair thymic negative selection of autoreactive T cells. PLoS One 9:e86677
Bottini, Nunzio; Peterson, Erik J (2014) Tyrosine phosphatase PTPN22: multifunctional regulator of immune signaling, development, and disease. Annu Rev Immunol 32:83-119

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