Persistent, aberrant myelopoiesis as etiological factor for chronic illness and metastatic disease.

Chronic illness and frailty can be supported by a state of enduring inflammation, immunosuppression and distorted catabolism. These alterations can persist for a long time after sepsis and cancer, as a consequence of a negative and persistent rewiring imparted upon myelopoiesis. In cancer, this negative training of myeloid progenitors favors the accumulation of myeloid cells that show intrinsic pro-tumoral features, such as immunosuppressive activity on adaptive immunity, induction of genome instability, support to distant dissemination of cancer cells and neoangiogenesis. Similarly, in septic patients, the persistence of unsolved and unbalanced hyperinflammation and immunosuppression points to myeloid compartment as the main culprit. As in metastatic patients, in post-septic patients, the long-term consequences of neverreached immune homeostasis, has been linked to the high rate of comorbidities and mortality. To understand the etiological bases of these conditions, we plan to dissect the epigenetic and transcriptional landscape of myeloid progenitors and characterize the molecular mechanisms sustaining a bad education that we define as ^negative training^. Indeed, there is accumulating evidence that myeloid cells retain the memory of a past exposure to microbes, so that the response is of higher magnitude at a subsequent encounter. This characteristic is known as trained immunity and it has been considered and view as protective against microbes and cancer (1-3). However, it is increasingly clear that this response can also be harmful, hence negative and ^maleducative/,, especially under chronic conditions. In this proposed project we plan to investigate: i) the transcriptional and epigenetic modifications that sustain the negative trained myelopoiesis in septic and cancer patients; ii) assess whether the negative trained myelopoiesis underlies comorbidities, including metastatic dissemination of the original tumor; iii) characterize and identify the molecular pathways underlying the negative-trained myelopoiesis. The etiopathogenesis and consequences of the persistence of unsolved inflammatioii'immunosuppression following sepsis and cancer development will be addressed by a combination of high- throughput technologies, such as scRNA-seq and scATAC-seq, mouse models of chronic sepsis and human immune reconstituted system, generation of hematopoietic precursors from induced pluripotent stem cells, newly established bone marrow tissue biobank, as well as a consolidated clinical management. The achievement of the main aims will be possible by the integrative collaboration of the participant UOs. In fact, each UO provides a specific expertise: UOl has a solid track-record in the field of immunology, pre-clinical model of cancers and surgical and clinical management of cancer patients; UO2 has a consolidated expertise in clinical care of patients with sepsis, thrombosis and chronic low-grade inflammation; UO3 has a proven pathological experience in both animal and human tissues, together with substantial statistics skills. Thus, by integrating clinical data and novel humanized mouse models, understanding the etiology of such altered myelopoiesis can lay the basis for the prevention and control of adverse clinical outcomes