Contributions
Abstract: EP384
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Extracellular vesicles (EVs) have emerged as a powerful reservoir of biomarkers for liquid biopsy in hematological malignancies. Indeed, EVs are small vesicles released by various blood cells and contain tumor-derived materials such as nucleic acids, proteins, and lipids. Interestingly, cell metabolism could be influenced by EVs through the regulation of redox processes. Of interest, redox metabolism plays a critical role in normal and leukemic hematopoiesis. Thus, although the role of EVs and their lipid cargo as disease biomarkers have been recently acknowledged in various diseases, the lipidomic profile of circulating EVs and their function on redox metabolism are still elusive in acute myeloid leukemia (AML).
Aims
We aimed to explore the lipidomic profile of EVs as a metabolic biomarker for AML and the effects of EVs on redox metabolism of hematopoietic stem/progenitor cells (HSPCs).
Methods
Peripheral blood was collected from AML patients at diagnosis (n=20) and healthy donors (HD, n=20). Immunomagnetically isolated CD34+ cells from umbilical cord blood or AML patients were characterized by analyzing the HSPC-specific cluster of differentiation marker expression, redox profiling (using CellROX, glutathione detection, and MitoTracker) after co-culture with circulating EVs from HD/AML. EVs were purified from platelet-poor plasma by size exclusion chromatography (SEC) and quantified using the NanoSight technology. Quantitative lipidomic profiling was performed by Liquid Chromatography coupled with High-Resolution Mass Spectrometry (LC/HRMS).
Results
In this study, we observed a significant increase in the size of AML EVs compared to HD counterparts (p= 0,008). Interestingly, more than 200 molecular lipid species were quantitatively identified in circulating EVs with a total of 25 (out of 200) independent lipid species significantly different between AML-derived EVs and HD. Notably, we reported the abundance of both glycerolipid and fatty acids (FA) species in AML EVs. Within bioactive lipid markedly increased in AML-derived EVs, fatty acid esters of hydroxy fatty acids (FAHFA-18:0_30) were inversely correlated to the percentage of leukemic blasts in the bone marrow (r= -0,72, p=0,009) suggesting the role as a putative biomarker of disease severity. Through a multivariate statistical analysis of EV lipid profile, we also revealed that AML EVs are depleted in sphingomyelin classes (SMs), a class of lipids that are interconnected to the modulation of oxidative stress. Moreover, after co-cultures of EVs with umbilical cord blood HSPCs, we observed that only EVs isolated from HD increased the granulocyte-macrophage progenitors (p=0.02). Conversely, both HD- (p=0.03) and AML-derived EVs (p=0.003) reduced the megakaryocyte erythroid progenitors. Next, we explored redox metabolism function driven by EVs and we demonstrated a reduction in AML HSPC fraction with high ROS levels in the presence of AML EVs (p=0.03). In parallel, AML EVs increased the proportion of AML HSPCs with both high glutathione and mitochondrial potential (p=0.03). Finally, according to the 2017 ELN risk stratification system, we found that EVs from patients with adverse risk were depleted in specific ether-linked phosphatidylethanolamine (EtherPE) and phosphatidylethanolamine (PE) species that are important modulators of EV release and formation.
Conclusion
This work provides a unique lipid signature of circulating EVs from AML patients and identifies prognostic biomarkers for patients' risk stratification that might reveal novel metabolic vulnerabilities driven by microenvironmental signals.
Keyword(s): Acute myeloid leukemia, CD34+ cells, Lipid metabolism, Microvesicles
Abstract: EP384
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Extracellular vesicles (EVs) have emerged as a powerful reservoir of biomarkers for liquid biopsy in hematological malignancies. Indeed, EVs are small vesicles released by various blood cells and contain tumor-derived materials such as nucleic acids, proteins, and lipids. Interestingly, cell metabolism could be influenced by EVs through the regulation of redox processes. Of interest, redox metabolism plays a critical role in normal and leukemic hematopoiesis. Thus, although the role of EVs and their lipid cargo as disease biomarkers have been recently acknowledged in various diseases, the lipidomic profile of circulating EVs and their function on redox metabolism are still elusive in acute myeloid leukemia (AML).
Aims
We aimed to explore the lipidomic profile of EVs as a metabolic biomarker for AML and the effects of EVs on redox metabolism of hematopoietic stem/progenitor cells (HSPCs).
Methods
Peripheral blood was collected from AML patients at diagnosis (n=20) and healthy donors (HD, n=20). Immunomagnetically isolated CD34+ cells from umbilical cord blood or AML patients were characterized by analyzing the HSPC-specific cluster of differentiation marker expression, redox profiling (using CellROX, glutathione detection, and MitoTracker) after co-culture with circulating EVs from HD/AML. EVs were purified from platelet-poor plasma by size exclusion chromatography (SEC) and quantified using the NanoSight technology. Quantitative lipidomic profiling was performed by Liquid Chromatography coupled with High-Resolution Mass Spectrometry (LC/HRMS).
Results
In this study, we observed a significant increase in the size of AML EVs compared to HD counterparts (p= 0,008). Interestingly, more than 200 molecular lipid species were quantitatively identified in circulating EVs with a total of 25 (out of 200) independent lipid species significantly different between AML-derived EVs and HD. Notably, we reported the abundance of both glycerolipid and fatty acids (FA) species in AML EVs. Within bioactive lipid markedly increased in AML-derived EVs, fatty acid esters of hydroxy fatty acids (FAHFA-18:0_30) were inversely correlated to the percentage of leukemic blasts in the bone marrow (r= -0,72, p=0,009) suggesting the role as a putative biomarker of disease severity. Through a multivariate statistical analysis of EV lipid profile, we also revealed that AML EVs are depleted in sphingomyelin classes (SMs), a class of lipids that are interconnected to the modulation of oxidative stress. Moreover, after co-cultures of EVs with umbilical cord blood HSPCs, we observed that only EVs isolated from HD increased the granulocyte-macrophage progenitors (p=0.02). Conversely, both HD- (p=0.03) and AML-derived EVs (p=0.003) reduced the megakaryocyte erythroid progenitors. Next, we explored redox metabolism function driven by EVs and we demonstrated a reduction in AML HSPC fraction with high ROS levels in the presence of AML EVs (p=0.03). In parallel, AML EVs increased the proportion of AML HSPCs with both high glutathione and mitochondrial potential (p=0.03). Finally, according to the 2017 ELN risk stratification system, we found that EVs from patients with adverse risk were depleted in specific ether-linked phosphatidylethanolamine (EtherPE) and phosphatidylethanolamine (PE) species that are important modulators of EV release and formation.
Conclusion
This work provides a unique lipid signature of circulating EVs from AML patients and identifies prognostic biomarkers for patients' risk stratification that might reveal novel metabolic vulnerabilities driven by microenvironmental signals.
Keyword(s): Acute myeloid leukemia, CD34+ cells, Lipid metabolism, Microvesicles