Chronic TNF in the Aging Microenvironment Exacerbates TET2-loss-of-Function Myeloid Expansion

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.938-938
• Main Authors: Quin, Candice, DeJong, Erica, McNaughton, Amy J. M., Buttigieg, Marco M., Basrai, Salman, Abelson, Sagi, Larche, Margaret, Rauh, Michael J., Bowdish, Dawn ME
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-189163

Introduction: Age-associated TET2 somatic mutations impart an intrinsic hematopoietic stem cell (HSC) advantage and contribute to the phenomenon of clonal hematopoiesis of indeterminate potential (CHIP). Individuals with TET2-mutantCHIP have a higher risk of developing myeloid neoplasms and other age-related conditions, including heart, lung, liver, kidney and infectious disease, and have increased risk of all-cause mortality. Despite its role in unhealthy aging, the extrinsic mechanisms driving TET2-mutant CHIP clonal expansion remain unclear. We previously showed an environment containing TNF favours TET2-mutant HSC expansion in vitro. We therefore postulated that age-related increases in TNF also provide an advantage to HSC and progeny with TET2-mutations in vivo. Methods: All human and mouse studies met ethics approval. C57Bl/6 background wildtype (WT), TNF-α knockout ( TNF-/-), Tet2 hematopoietic knockout (Vav1-iCre-mediated; Tet2-/-) and floxed control mice ( Tet2f/f) mice were obtained from the Jackson Laboratory. Young (6-mo [n=9]) and old (18-22 mo [n=9]) WT mice, and old TNF-/- mice (n=7) were subjected to nonirradiative myeloablation with busulfan, and retro-orbital injections of 8x10 6 cells/ml T-cell-depleted bone marrow (BM), equally harvested from 4-mo-old WT CD45.1 (n=5) and Tet2-/- CD45.2 donor mice (n=5). Flow cytometry was used to confirm and monitor engraftment. Mice were harvested 8 weeks post-transplant for analysis of HSC, progenitor, monocyte and neutrophil populations, and cytokine analyses. Consenting human research participants diagnosed with rheumatoid arthritis (RA) were recruited from the Greater Hamilton Area (Ontario, Canada) from 2016-2018. Blood draws occurred prior to any immunomodulatory treatment (baseline), and at 3- and 6-months following treatment with Adalimumab (Humira®), an anti-TNF agent. CHIP status was determined with our successful 48-gene, targeted, Ion-Torrent based sequencing approach to isolated genomic DNA from PBMC. Confirmation of calls and increased sensitivity to detect clones with VAF < 0.02 employed our established single molecule molecular inversion probes (smMIP)-targeted genomic capture technique and high-depth (47,500X avg. coverage) paired-end sequencing, employing high-stringency filters for error-suppression. Statistical analyses were performed in GraphPad Prism V9.2 or R 4.1.2. Results: 1. Mixed BM chimeric mice of WT and TNF -/- genotypes reconstituted with WT CD45.1 + and Tet2 -/- CD45.2 +