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Myelomonocytic cells in giant cell arteritis activate trained immunity programs sustaining inflammation and cytokine production.

Rheumatology (Oxford, England)

Authors: Eleonora Cantoni, Ivan Merelli, Davide Stefanoni, Alessandro Tomelleri, Corrado Campochiaro, Vito Giordano, Maddalena Panigada, Elena M Baldissera, Laura Merlo Pich, Valentina Natoli, Athanasios Ziogas, Jorge Domínguez-Andrés, Giacomo De Luca, Davide Mazza, Samuel Zambrano, Daniela Gnani, Marina Ferrarini, Elisabetta Ferrero, Alessandra Agresti, Barbara Vergani, Biagio Eugenio Leone, Simone Cenci, Angelo Ravelli, Marco Matucci-Cerinic, Angelo D'Alessandro, Leo A B Joosten, Lorenzo Dagna, Mihai G Netea, Raffaella Molteni, Giulio Cavalli

OBJECTIVE: Trained immunity (TI) is a de facto memory program of innate immune cells, characterized by immunometabolic and epigenetic changes sustaining enhanced production of cytokines. TI evolved as a protective mechanism against infections; however, inappropriate activation can cause detrimental inflammation and might be implicated in the pathogenesis of chronic inflammatory diseases. In this study, we investigated the role of TI in the pathogenesis of giant cell arteritis (GCA), a large-vessel vasculitis characterized by aberrant macrophage activation and excess cytokine production.

METHODS: Monocytes from GCA patients and from age- and sex-matched healthy donors were subjected to polyfunctional studies, including cytokine production assays at baseline and following stimulation, intracellular metabolomics, chromatin immunoprecipitation-qPCR, and combined ATAC/RNA sequencing. Immunometabolic activation (i.e. glycolysis) was assessed in inflamed vessels of GCA patients with FDG-PET and immunohistochemistry (IHC), and the role of this pathway in sustaining cytokine production was confirmed with selective pharmacologic inhibition in GCA monocytes.

RESULTS: GCA monocytes exhibited hallmark molecular features of TI. Specifically, these included enhanced IL-6 production upon stimulation, typical immunometabolic changes (e.g. increased glycolysis and glutaminolysis) and epigenetic changes promoting enhanced transcription of genes governing pro-inflammatory activation. Immunometabolic changes of TI (i.e. glycolysis) were a feature of myelomonocytic cells in GCA lesions and were required for enhanced cytokine production.

CONCLUSIONS: Myelomonocytic cells in GCA activate TI programs sustaining enhanced inflammatory activation with excess cytokine production.

© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

PMID: 36802235

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