title: Role of macrophage receptor with collagenous structure in innate immune tolerance.
abstract: Macrophages play a key role in host defense against microbes, in part, through phagocytosis. Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor on the cell surface of macrophages that mediates opsonin-independent phagocytosis. The goal of our study is to investigate the role of MARCO in LPS or lipotechoic acid-induced macrophage tolerance. Although it has been established that expression of MARCO and phagocytosis is increased in tolerant macrophages, the transcriptional regulation and biological role of MARCO in tolerant macrophages have not been investigated. In this study, we confirm that tolerized mouse bone marrow-derived macrophages (BMDM) selectively increase expression of MARCO (both transcript and cell surface receptor) and increase phagocytosis. We found that H3K4me3 dynamic modification of a promoter site of MARCO was increased in tolerized BMDM. Blocking methylation by treatment with 5-aza-2'-deoxycytidine resulted in reduced H3K4me3 binding in the promoter of MARCO, decreased expression of MARCO, and impaired phagocytosis in tolerized BMDM. However, 5-aza-2'-deoxycytidine had no effect on the inflammatory component of innate immune tolerance. In aggregate, we found that histone methylation was critical to MARCO expression and phagocytosis in tolerized macrophages, but did not affect the inflammatory component of innate immune tolerance.
authors.affiliation: Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Jing
authors.forename: Ivana V
authors.initials: IV
authors.lastname: Yang
authors.forename: Lucy
authors.initials: L
authors.lastname: Hui
authors.forename: Jay A
authors.initials: JA
authors.lastname: Patel
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Evans
authors.forename: Rytis
authors.initials: R
authors.lastname: Prikeris
authors.forename: Lester
authors.initials: L
authors.lastname: Kobzik
authors.forename: Brian P
authors.initials: BP
authors.lastname: O'Connor
authors.forename: David A
authors.initials: DA
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000276:immunology; D002469:Cell Separation; D016207:Cytokines / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D007108:Immune Tolerance / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D020411:Oligonucleotide Array Sequence Analysis; D010587:Phagocytosis / Q000276:immunology; D060888:Real-Time Polymerase Chain Reaction; D011971:Receptors, Immunologic / Q000276:immunology*
chemical_list: D016207:Cytokines; C092228:Marco protein, mouse; D011971:Receptors, Immunologic