Purine nucleoside phosphorylase enables dual metabolic checkpoints that prevent T cell immunodeficiency and TLR7-associated autoimmunity
Evan R. Abt, Khalid Rashid, Thuc M. Le, Suwen Li, Hailey R. Lee, Vincent Lok, Luyi Li, Amanda L. Creech, Amanda N. Labora, Hanna K. Mandl, Alex K. Lam, Arthur Cho, Valerie Rezek, Nanping Wu, Gabriel Abril-Rodriguez, Ethan W. Rosser, Steven D. Mittelman, Willy Hugo, Thomas Mehrling, Shanta Bantia, Antoni Ribas, Timothy R. Donahue, Gay M. Crooks, Ting-Ting Wu, Caius G. Radu
Evan R. Abt, Khalid Rashid, Thuc M. Le, Suwen Li, Hailey R. Lee, Vincent Lok, Luyi Li, Amanda L. Creech, Amanda N. Labora, Hanna K. Mandl, Alex K. Lam, Arthur Cho, Valerie Rezek, Nanping Wu, Gabriel Abril-Rodriguez, Ethan W. Rosser, Steven D. Mittelman, Willy Hugo, Thomas Mehrling, Shanta Bantia, Antoni Ribas, Timothy R. Donahue, Gay M. Crooks, Ting-Ting Wu, Caius G. Radu
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Research Article Immunology Metabolism

Purine nucleoside phosphorylase enables dual metabolic checkpoints that prevent T cell immunodeficiency and TLR7-associated autoimmunity

Abstract

Purine nucleoside phosphorylase (PNP) enables the breakdown and recycling of guanine nucleosides. PNP insufficiency in humans is paradoxically associated with both immunodeficiency and autoimmunity, but the mechanistic basis for these outcomes is incompletely understood. Here, we identify two immune lineage-dependent consequences of PNP inactivation dictated by distinct gene interactions. During T cell development, PNP inactivation is synthetically lethal with downregulation of the dNTP triphosphohydrolase SAMHD1. This interaction requires deoxycytidine kinase activity and is antagonized by microenvironmental deoxycytidine. In B lymphocytes and macrophages, PNP regulates Toll-like receptor 7 signaling by controlling the levels of its (deoxy)guanosine nucleoside ligands. Overriding this regulatory mechanism promotes germinal center formation in the absence of exogenous antigen and accelerates disease in a mouse model of autoimmunity. This work reveals that one purine metabolism gene protects against immunodeficiency and autoimmunity via independent mechanisms operating in distinct immune lineages and identifies PNP as a potentially novel metabolic immune checkpoint.

Authors

Evan R. Abt, Khalid Rashid, Thuc M. Le, Suwen Li, Hailey R. Lee, Vincent Lok, Luyi Li, Amanda L. Creech, Amanda N. Labora, Hanna K. Mandl, Alex K. Lam, Arthur Cho, Valerie Rezek, Nanping Wu, Gabriel Abril-Rodriguez, Ethan W. Rosser, Steven D. Mittelman, Willy Hugo, Thomas Mehrling, Shanta Bantia, Antoni Ribas, Timothy R. Donahue, Gay M. Crooks, Ting-Ting Wu, Caius G. Radu

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Figure 5

PNPi elevates cytokine levels and modifies the transcriptional phenotype of splenocytes.

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PNPi elevates cytokine levels and modifies the transcriptional phenotype...
(A) Analysis of C57BL/6 mice treated with or without 100 mg/kg ulodesine (PNPi; p.o.; q.d.) and 75 mg/kg (R)-DI-87 (dCKi; p.o.; b.i.d.) for 13 days (n = 4; Kruskal-Wallis test with Dunn’s multiple comparisons correction). (B) Flow cytometry analysis of spleen cellular composition from experiment in A. (C) Luminex serum cytokine profile of C57BL/6 mice 6 hours after treatment with or without PNPi (100 mg/kg; p.o.). (D) RT-PCR analysis of tissue cytokine transcript levels from C57BL/6 mice 6 hours after treatment with or without PNPi (100 mg/kg; n = 4). (E) UMAP projection of splenocytes (6701 from the vehicle-treated group and 6412 from the PNPi-treated group). scRNA-Seq analysis was performed on splenocytes isolated from C57BL/6 mice 6 hours after treatment with or without PNPi (100 mg/kg; p.o.; splenocytes from 3 mice/group were pooled before sequencing). (F) UMAP projection and clustering of vehicle and PNPi groups. (G) Ontology analysis of significantly altered transcripts in select B cell (B1 and B2) and macrophage (MK) clusters. (H) Feature plot analysis of PNPi-induced expression alterations in B cell and macrophage clusters. **P < 0.01.