TET2-loss enhances immediate and time-resolved IFNγ 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 CyTOF panel of both surface marker and phosphoprotein antigens in murine BM. We show diverse, cell-type specific inflammatory cytokine responses in healthy hematopoietic cells. We next investigated changes associated with bone marrow cells from Tet2 mice. High dimensional surface marker phenotyping revealed expansion of HSPCs, committed cKITLy6C myeloid progenitors, and monocytes. Loss of TET2 function increased the magnitude of response to extracellular perturbations, including IFNγ and HO. Response time courses revealed that IFNγ-mediated pSTAT1 remains elevated over time in Tet2. Further, IFNγ resulted in a more significant increase in major histocompatibility complex class II (MHCII) expression in Tet2 immortalized progenitor cells than in Tet2. Inhibition of Janus kinase 1 and 2 (JAK1/2) with ruxolitinib significantly reduced STAT1 phosphorylation and MHCII expression in Tet2 cells. Our results identify targetable disrupted signaling responses in Tet2 cells.