The biology of nematode- and IL4Rα-dependent murine macrophage polarization in vivo as defined by RNA-Seq and targeted lipidomics.
Alternatively activated macrophages (AAMϕ) are a major component of the response to helminth infection; however, their functions remain poorly defined. To better understand the helminth-induced AAMϕ phenotype, we performed a systems-level analysis of in vivo derived AAMϕ using an established mouse model. With next-generation RNA sequencing, we characterized the transcriptomes of peritoneal macrophages from BALB/c and IL4Rα(-/-) mice elicited by the nematode Brugia malayi, or via intraperitoneal thioglycollate injection. We defined expression profiles of AAMϕ-associated cytokines, chemokines, and their receptors, providing evidence that AAMϕ contribute toward recruitment and maintenance of eosinophilia. Pathway analysis highlighted complement as a potential AAMϕ-effector function. Up-regulated mitochondrial genes support in vitro evidence associating mitochondrial metabolism with alternative activation. We mapped macrophage transcription start sites, defining over-represented cis-regulatory motifs within AAMϕ-associated promoters. These included the binding site for PPAR transcription factors, which maintain mitochondrial metabolism. Surprisingly PPARγ, implicated in the maintenance of AAMϕ, was down-regulated on infection. PPARδ expression, however, was maintained. To explain how PPAR-mediated transcriptional activation could be maintained, we used lipidomics to quantify AAMϕ-derived eicosanoids, potential PPAR ligands. We identified the PPARδ ligand PGI(2) as the most abundant AAMϕ-derived eicosanoid and propose a PGI(2)-PPARδ axis maintains AAMϕ during B malayi implantation.
Institute of Immunology and Infection Research and Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Graham D
GD
Thomas
Dominik
D
Rückerl
Benjamin H
BH
Maskrey
Phillip D
PD
Whitfield
Mark L
ML
Blaxter
Judith E
JE
Allen
D000818:Animals; D001777:Blood Coagulation; D017178:Brugia malayi / Q000502:physiology*; D018925:Chemokines / Q000235:genetics; D003165:Complement System Proteins / Q000235:genetics; D016207:Cytokines / Q000235:genetics; D015777:Eicosanoids / Q000378:metabolism; D005368:Filariasis / Q000469:parasitology*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006790:Host-Parasite Interactions; D008262:Macrophage Activation; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology*; D019707:Receptors, Chemokine / Q000235:genetics; D018121:Receptors, Cytokine / Q000235:genetics; D059467:Transcriptome; D053662:Interleukin-4 Receptor alpha Subunit
D018925:Chemokines; D003165:Complement System Proteins; D016207:Cytokines; D015777:Eicosanoids; D047492:Peroxisome Proliferator-Activated Receptors; D012313:RNA; D011956:Receptors, Cell Surface; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine; C504002:Il4ra protein, mouse; D053662:Interleukin-4 Receptor alpha Subunit