Contributions
Abstract: P462
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - 15 Immunology
Background: The clearance of myelin debris by phagocytic monocyte-derived macrophages (MDMs) is essential for tissue repair in multiple sclerosis (MS). A selective defect in myelin phagocytosis but not in uptake of opsonized red blood cells by MS MDMs has been previously demonstrated (Natrajan 2015, Healy 2017). The metabolic state of MDMs, defined on the basis of oxidative phosphorylation (OXPHOS) and glycolysis, has been linked with the activation state of MDMs.
Objective: The aims of this study were to determine whether the metabolic activity of MDMs influences the rate of myelin phagocytosis, and then determine whether there was defect in metabolic activity of MS patient-derived MDMs.
Methods: MDMs were prepared by isolating monocytes from whole venous blood samples derived from control donors and untreated MS patients (1 relapsing and 4 secondary progressive) and culturing these cells for 1 week in macrophage colony stimulating factor (M-CSF)-supplemented media. Myelin phagocytosis was measured using pHrodo-labelled myelin in a flow cytometry assay as described (Healy 2016). A Seahorse bioanalyzer was used to measure oxygen consumptions rates that predominantly reflect OXPHOS, and extracellular acidification rates that mainly reflect glycolysis.
Results: Both OXPHOS and glycolytic metabolism were upregulated in control donor MDMs following myelin uptake. Blocking OXPHOS by addition of the ATP synthase inhibitor oligomycin significantly reduced myelin phagocytosis. Blocking glycolysis by addition of the competitive inhibitor 2-deoxyglucose (2DG) did not reduce phagocytosis but did modulate subsequent cytokine production following phagocytosis. MS patient-derived MDMs showed significant deficits in both basal OXPHOS and glycolytic metabolism.
Conclusion: Our data using control donor MDMs indicate a central role for OXPHOS in the control of myelin phagocytosis by healthy donor-derived MDMs. MDMs from MS patients display a deficit in both myelin phagocytosis and basal metabolic activity. The basis of this metabolic defect in MS MDMs remains to be defined.
Disclosure:
Yun Hsuan Lin: nothing to disclose.
Luke M. Healy: nothing to disclose.
Jeong Ho Jang: nothing to disclose.
Vijayaraghava TS Rao: nothing to disclose.
Amit Bar-Or: nothing to disclose.
Jack P. Antel: nothing to disclose.
This study was funded by the MS Society of Canada.
Abstract: P462
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - 15 Immunology
Background: The clearance of myelin debris by phagocytic monocyte-derived macrophages (MDMs) is essential for tissue repair in multiple sclerosis (MS). A selective defect in myelin phagocytosis but not in uptake of opsonized red blood cells by MS MDMs has been previously demonstrated (Natrajan 2015, Healy 2017). The metabolic state of MDMs, defined on the basis of oxidative phosphorylation (OXPHOS) and glycolysis, has been linked with the activation state of MDMs.
Objective: The aims of this study were to determine whether the metabolic activity of MDMs influences the rate of myelin phagocytosis, and then determine whether there was defect in metabolic activity of MS patient-derived MDMs.
Methods: MDMs were prepared by isolating monocytes from whole venous blood samples derived from control donors and untreated MS patients (1 relapsing and 4 secondary progressive) and culturing these cells for 1 week in macrophage colony stimulating factor (M-CSF)-supplemented media. Myelin phagocytosis was measured using pHrodo-labelled myelin in a flow cytometry assay as described (Healy 2016). A Seahorse bioanalyzer was used to measure oxygen consumptions rates that predominantly reflect OXPHOS, and extracellular acidification rates that mainly reflect glycolysis.
Results: Both OXPHOS and glycolytic metabolism were upregulated in control donor MDMs following myelin uptake. Blocking OXPHOS by addition of the ATP synthase inhibitor oligomycin significantly reduced myelin phagocytosis. Blocking glycolysis by addition of the competitive inhibitor 2-deoxyglucose (2DG) did not reduce phagocytosis but did modulate subsequent cytokine production following phagocytosis. MS patient-derived MDMs showed significant deficits in both basal OXPHOS and glycolytic metabolism.
Conclusion: Our data using control donor MDMs indicate a central role for OXPHOS in the control of myelin phagocytosis by healthy donor-derived MDMs. MDMs from MS patients display a deficit in both myelin phagocytosis and basal metabolic activity. The basis of this metabolic defect in MS MDMs remains to be defined.
Disclosure:
Yun Hsuan Lin: nothing to disclose.
Luke M. Healy: nothing to disclose.
Jeong Ho Jang: nothing to disclose.
Vijayaraghava TS Rao: nothing to disclose.
Amit Bar-Or: nothing to disclose.
Jack P. Antel: nothing to disclose.
This study was funded by the MS Society of Canada.