Ioannis Kourtzelis

Macrophage phagocytosis has been implicated in regulating anti-tumour immunity. Trained innate immunity (TII), induced via modulation of mature myeloid cells or their bone marrow progenitors, mediates sustained increased responsiveness to secondary challenges. Despite the advances in the study of TII-mediated anti-tumour activity, the impact of TII on the orchestration of phagocytosis in the tumour setting requires further elucidation. Here, we investigated whether macrophage phagocytosis of tumour cells can be modulated through induction of TII. To this end, mice were pre-treated with β-glucan, a fungal-derived agonist of TII, and bone marrow was isolated for macrophage differentiation. Macrophages were then co-cultured with tumour cells that were either apoptotic or opsonised with an antibody recognising a tumour antigen, to mimic efferocytosis and antibody-dependent cellular phagocytosis (ADCP), respectively. While TII did not have any impact in the modulation of ADCP, efferocytosis was decreased in trained macrophages. Along the same line, gene expression analysis demonstrated that mRNA levels of molecules promoting efferocytosis were downregulated in trained macrophages. Trained macrophages exerted decreased levels of active caspase-1 and produced decreased levels of interleukin-1β upon efferocytosis of tumour cells. Our findings reveal a hitherto unknown role of TII in the regulation of anti-tumour immunity and may set the stage for designing new cancer immunotherapeutic approaches targeting macrophage efferocytosis.

L-Tryptophan (Trp) is an essential amino acid, catabolised through the kynurenine pathway, which is mediated by the enzymes indoleamine-2,3-dioxygenase 1 (IDO1), IDO2, or Trp-2,3-deoxygenase (TDO). Therapeutic targeting of Trp metabolism could be relevant to several pathologies. In cancer, IDO1 acts as an immune checkpoint suppressing effector T cell function. Yet, direct inhibition of IDO1 has had limited success in clinical trials. Therefore, alternative approaches to Trp metabolism therapeutic targeting are needed. We screened a library of 597 natural products (NPs) or NP derivatives for their effect on kynurenine production in triple negative breast cancer cells. This revealed 24 candidate inhibitors of kynurenine production. Amongst them, artemether, a member of the artemisinin family of anti-malarial drugs, suppressed kynurenine production, likely via an endoperoxide bridge-dependent mechanism. The Euphorbia factor L9 (EFL9) inhibited kynurenine production likely via a C7-benzoylation-dependent mechanism. Neither artemether nor EFL9 affected JAK/STAT signaling or IDO1 levels. Targeted metabolomics analyses demonstrated that artemether suppressed kynurenine production through heme sequestration, a mechanism that would affect all members of the IDO/TDO family of metalloenzymes. EFL9 affected purine and amino acid metabolism and the cellular redox balance. Comparisons to the effects of ouabain, a NP regulator of IDO1 levels, and Linrodostat, a clinically used small molecule IDO1 inhibitor, revealed distinct metabolic profiles, with ouabain and EFL9 showing the largest overlap. Importantly, the kynurenine-suppressing activity of artemether and EFL9 is not cancer cell-specific. Overall, our findings set the foundation for the use of derivatives of artemether or EFL9 as novel Trp metabolism-targeting therapeutics.

Data sheet 3 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine

Supplementary Figures and Tables

Data sheet 1 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine

Data sheet 2 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine

Data sheet 3 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine

Data sheet 2 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine

Supplementary Figures and Tables

Data sheet 1 from Single-Cell Analysis of Bone Marrow CD8+ T Cells in Myeloid Neoplasms Reveals Pathways Associated with Disease Progression and Response to Treatment with Azacitidine