title: Higher phagocytic activity of thioglycollate-elicited peritoneal macrophages is related to metabolic status of the cells.
abstract: BACKGROUND
  Peritoneal macrophages are widely used in immunological studies. The cells can be collected under non-elicited (resident) or elicited (e.g., with Brewer thioglycollate broth injection) conditions, and their phenotype and functions differ. Recent studies have shown that macrophage phenotype and function are related to their metabolic states, and metabolic reprogramming has been an emerging concept for controlling macrophage function. In this study, we examined the metabolic state of resident and elicited macrophages and investigated how their metabolic state may affect cell function, including phagocytosis.
  
  
  RESULTS
  Flow cytometry showed that elicited macrophages expressed higher levels of MHC-II, LFA-1 and CD64 but lower levels of F4/80 compared to naïve resident peritoneal macrophages, suggesting a more mature and active phenotype. Elicited macrophages had significantly higher levels of phagocytic activity compared to that of resident macrophages. Metabolic studies showed that the Extracellular Acidification Rates (ECAR) and Oxygen Consumption Rates (OCR) were both significantly higher in elicited macrophages than those in resident macrophages. The treatment of macrophages with 2-Deoxy-D-glucose suppressed glycolysis and reduced phagocytosis, whereas treatment with oligomycin enhanced glycolysis and increased phagocytosis in elicited macrophages.
  
  
  CONCLUSIONS
  Naïve resident peritoneal macrophages are less metabolically active compared to elicited macrophages. Elicited macrophages had higher levels of glycolysis and oxidative phosphorylation, which may be related to their increased phagocytic capacity and higher levels of maturation and activation. Further understanding of the molecular links between metabolic pathways and cell function would be crucial to develop strategies to control macrophage function through metabolic reprogramming.
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK.
authors.forename: Sofia
authors.initials: S
authors.lastname: Pavlou
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK.
authors.forename: Luxi
authors.initials: L
authors.lastname: Wang
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK.
authors.forename: Heping
authors.initials: H
authors.lastname: Xu
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Science, Queens University Belfast, Belfast, Northern Ireland UK.
authors.forename: Mei
authors.identifier: 0000-0001-5661-1386
authors.initials: M
authors.lastname: Chen
keywords: Extracellular acidification rate; Function; Glycolysis; Peritoneal macrophages; Phagocytosis