TET2-loss enhances immediate and time-resolved interferon-γ signaling responses across myeloid differentiation

Signaling responses to cytokines are disrupted in clonal hematopoiesis and myeloid malignancies. To better identify specific signaling response alterations in the presence or absence of TET2, we developed a 36-parameter cytometry by time-of-flight (CyTOF) panel of both surface marker and phosphoprotein antigens in murine bone marrow (BM). We show diverse, cell-type specific inflammatory cytokine responses in healthy hematopoietic cells. We next investigated changes associated with BM cells from Tet2^KO mice. High-dimensional surface marker phenotyping revealed expansion of hematopoietic stem and progenitor cells (HSPCs), committed cKIT⁺Ly6C⁺ myeloid progenitors, and monocytes. Loss of TET2 function increased the magnitude of response to extracellular perturbations, including interferon (IFN)γ and H₂O₂. Response time courses revealed that IFNγ-mediated pSTAT1 remains elevated over time in Tet2^KO. Further, IFNγ resulted in a more significant increase in major histocompatibility complex class II (MHCII) expression in Tet2^KO immortalized progenitor cells than in Tet2^WT. Inhibition of Janus kinase 1 and 2 (JAK1/2) with ruxolitinib significantly reduced STAT1 phosphorylation and MHCII expression in Tet2^KO cells. Our results identify targetable disrupted signaling responses in Tet2^KO cells.