title: Microenvironments in tuberculous granulomas are delineated by distinct populations of macrophage subsets and expression of nitric oxide synthase and arginase isoforms.
abstract: Macrophages in granulomas are both antimycobacterial effector and host cell for Mycobacterium tuberculosis, yet basic aspects of macrophage diversity and function within the complex structures of granulomas remain poorly understood. To address this, we examined myeloid cell phenotypes and expression of enzymes correlated with host defense in macaque and human granulomas. Macaque granulomas had upregulated inducible and endothelial NO synthase (iNOS and eNOS) and arginase (Arg1 and Arg2) expression and enzyme activity compared with nongranulomatous tissue. Immunohistochemical analysis indicated macrophages adjacent to uninvolved normal tissue were more likely to express CD163, whereas epithelioid macrophages in regions where bacteria reside strongly expressed CD11c, CD68, and HAM56. Calprotectin-positive neutrophils were abundant in regions adjacent to caseum. iNOS, eNOS, Arg1, and Arg2 proteins were identified in macrophages and localized similarly in granulomas across species, with greater eNOS expression and ratio of iNOS/Arg1 expression in epithelioid macrophages as compared with cells in the lymphocyte cuff. iNOS, Arg1, and Arg2 expression in neutrophils was also identified. The combination of phenotypic and functional markers support that macrophages with anti-inflammatory phenotypes localized to outer regions of granulomas, whereas the inner regions were more likely to contain macrophages with proinflammatory, presumably bactericidal, phenotypes. Together, these data support the concept that granulomas have organized microenvironments that balance antimicrobial anti-inflammatory responses to limit pathology in the lungs.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15261, USA.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Mattila
authors.forename: Olabisi O
authors.initials: OO
authors.lastname: Ojo
authors.forename: Diane
authors.initials: D
authors.lastname: Kepka-Lenhart
authors.forename: Simeone
authors.initials: S
authors.lastname: Marino
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Seok Yong
authors.initials: SY
authors.lastname: Eum
authors.forename: Laura E
authors.initials: LE
authors.lastname: Via
authors.forename: Clifton E
authors.initials: CE
authors.lastname: Barry
authors.forename: Edwin
authors.initials: E
authors.lastname: Klein
authors.forename: Denise E
authors.initials: DE
authors.lastname: Kirschner
authors.forename: Sidney M
authors.initials: SM
authors.lastname: Morris
authors.forename: Philana Ling
authors.initials: PL
authors.lastname: Lin
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Flynn
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001119:Arginase / Q000378:metabolism*; D039521:CD11c Antigen / Q000378:metabolism; D060833:Cellular Microenvironment; D006099:Granuloma / Q000276:immunology*; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000378:metabolism; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008251:Macaca; D008264:Macrophages / Q000166:cytology*; D009169:Mycobacterium tuberculosis / Q000276:immunology; D022423:Myeloid Cells; D009504:Neutrophils / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D014376:Tuberculosis / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D000098902:CD163 Antigen; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D001119:Arginase; D039521:CD11c Antigen; D039841:Leukocyte L1 Antigen Complex; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D000098902:CD163 Antigen; C067980:CD68 antigen, human; D000097382:CD68 Molecule