Multi-omic analysis of chronic myelomonocytic leukemia monocytes reveals metabolic and immune dysregulation leading to altered macrophage polarization [RNAseq]

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative overlap neoplasm with few treatment options and generally poor prognosis. A defining feature is expansion of classical monocytes, which are responsible for various clinical sequelae and thus represent viable therapeutic targets. Given the near-ubiquity of mutations involving epigenetic regulators, we profiled the epigenome (open chromatin configuration; H3K4-monomethylation; H3K27-acetylation; H3K27/H3K4-trimethylation) and transcriptome of primary CD14+ monocytes from CMML patients and age-matched healthy controls. Compared with healthy monocytes, CMML monocytes displayed heterogeneous but distinct epigenetic and transcriptome signatures. Most epigenetic changes mapped to distal elements, suggesting generalized enhancer dysregulation. We observed strong epigenetic (but not transcriptional) suppression of the NF-κB pathway, suggesting poised potential to repress downstream targets and modulate inflammatory responses. RNA-seq revealed up-regulation of genes involved in the oxidative phosphorylation (OxPhos) machinery, with significantly heightened OxPhos activity of primary CMML monocytes validated in mitochondrial stress tests, highlighting a potentially tractable therapeutic vulnerability. In line with the observed metabolic phenotype of CMML monocytes, unpolarized CMML monocyte-derived macrophages exhibited transcriptional bias towards an M2 (“anti-inflammatory”) phenotype, reflected by an increased Th2/Th1 ratio in comparison with control monocytes. These observations may be germane to the observed clinical heterogeneity and prominent immune dysfunction characteristic of CMML.