title: Innate cytokine profiling of bovine alveolar macrophages reveals commonalities and divergence in the response to Mycobacterium bovis and Mycobacterium tuberculosis infection.
abstract: Despite sharing >99.9% genome sequence similarity at the nucleotide level, Mycobacterium tuberculosis and Mycobacterium bovis-the causative agents of human and bovine tuberculosis, respectively-exhibit distinct host preferences. M. bovis can cause disease in both cattle and humans yet rarely transmits between immuno-competent human hosts, while M. tuberculosis is a highly successful pathogen of humans that does not sustain in animal populations. Based on the key role played by alveolar macrophages during mycobacterial infection, we hypothesised that the immunological and pathological differences observed in cattle infected with virulent M. bovis and M. tuberculosis may have a basis in innate immune mechanisms; these differences, in turn, would be reflected at the macrophage mRNA and protein level. To investigate this, we have analysed the transcriptional profile of innate immune genes in bovine alveolar macrophages following 24 and 48 h infection with the genome-sequenced strains, M. bovis AF2122/97 and M. tuberculosis H37Rv. A bespoke multiplex ELISA was also used to quantify corresponding cytokine secretion in supernatants from the same infected alveolar macrophages. All cytokines showed similar significant patterns of expression (i.e., up- or down-regulation) at both the mRNA and protein levels in infected macrophages relative to parallel non-infected controls at the two time points (P ≤ 0.05). However, significant upregulation and downregulation of several innate immune genes-including TLR2, FOS, PIK3IP1, CCL4, IL1B, IL6 and TNF-and the CCL-4 protein was observed in the M. bovis-infected macrophages relative to the M. tuberculosis-infected macrophages 48 h post-infection (P ≤ 0.05). These results support the hypothesis that the divergent virulence of M. bovis and M. tuberculosis in cattle has a basis in innate immune mechanisms, which may contribute to host preference within the M. tuberculosis complex of strains.
authors.affiliation: Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: david.magee@ucd.ie.
authors.forename: David A
authors.initials: DA
authors.lastname: Magee
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Conlon
authors.affiliation: Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Nicolas C
authors.initials: NC
authors.lastname: Nalpas
authors.affiliation: Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: John A
authors.initials: JA
authors.lastname: Browne
authors.affiliation: Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, Surrey, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Pirson
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Claire
authors.initials: C
authors.lastname: Healy
authors.affiliation: Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: McLoughlin
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, Surrey, United Kingdom.
authors.forename: H Martin
authors.initials: HM
authors.lastname: Vordermeier
authors.affiliation: Tuberculosis Diagnostics and Immunology Research Centre, UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Eamonn
authors.initials: E
authors.lastname: Gormley
authors.affiliation: Animal Genomics Laboratory, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: David E
authors.initials: DE
authors.lastname: MacHugh
authors.affiliation: UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland; UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Gordon
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000382:microbiology; D008297:Male; D009163:Mycobacterium bovis / Q000276:immunology / Q000472:pathogenicity*; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000235:genetics; D014380:Tuberculosis, Bovine / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D016207:Cytokines; D012333:RNA, Messenger
keywords: Alveolar macrophage; Bovine; Cytokine; Gene expression; Mycobacterium bovis; Mycobacterium tuberculosis