title: TLR9 is required for MAPK/NF-κB activation but does not cooperate with TLR2 or TLR6 to induce host resistance to Brucella abortus.
abstract: Brucella abortus is a Gram-negative intracellular bacterial pathogen that causes a zoonosis of worldwide occurrence, leading to undulant fever in humans and abortion in domestic animals. B. abortus is recognized by several pattern-recognition receptors triggering pathways during the host innate immune response. Therefore, here, we determined the cooperative role of TLR9 with TLR2 or TLR6 receptors in sensing Brucella Furthermore, we deciphered the host innate immune response against B. abortus or its DNA, emphasizing the role of TLR9-MAPK/NF-κB signaling pathways in the production of proinflammatory cytokines. TLR9 is required for the initial host control of B. abortus, but this TLR was dispensable after 6 wk of infection. The susceptibility of TLR9(-/-)-infected animals to Brucella paralleled with lower levels of IFN-γ produced by mouse splenocytes stimulated with this pathogen compared with wild-type cells. However, no apparent cooperative interplay was observed between TLR2-TLR9 or TLR6-TLR9 receptors to control infection. Moreover, B. abortus or its DNA induced activation of MAPK/NF-κB pathways and production of IL-12 and TNF-α by macrophages partially dependent on TLR9 but completely dependent on MyD88. In addition, B. abortus-derived CpG oligonucleotides required TLR9 to promote IL-12 and TNF-α production by macrophages. By confocal microscopy, we demonstrated that TLR9 redistributed and colocalized with lysosomal-associated membrane protein-1 upon Brucella infection. Thus, B. abortus induced TLR9 traffic, leading to cell signaling activation and IL-12 and TNF-α production. Although TLR9 recognized Brucella CpG motifs, our results suggest a new pathway of B. abortus DNA-activating macrophages independent of TLR9.
authors.affiliation: Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;
authors.forename: Marco Túlio
authors.initials: MT
authors.lastname: Gomes
authors.affiliation: Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;
authors.forename: Priscila Carneiro
authors.initials: PC
authors.lastname: Campos
authors.affiliation: Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;
authors.forename: Guilherme de Sousa
authors.initials: Gde S
authors.lastname: Pereira
authors.affiliation: Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; and.
authors.forename: Daniella Castanheira
authors.initials: DC
authors.lastname: Bartholomeu
authors.affiliation: Department of Pathobiological Sciences, University of Wisconsin-Madison School of Veterinary Medicine, Madison, Wisconsin, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Splitter
authors.affiliation: Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; scozeus@icb.ufmg.br.
authors.forename: Sergio Costa
authors.initials: SC
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D002003:Brucella abortus / Q000276:immunology*; D002006:Brucellosis / Q000382:microbiology / Q000473:pathology; D004269:DNA, Bacterial / Q000378:metabolism; D060467:Disease Resistance / Q000276:immunology*; D054884:Host-Pathogen Interactions; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D008264:Macrophages / Q000378:metabolism; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D015398:Signal Transduction; D013154:Spleen / Q000378:metabolism / Q000473:pathology; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D051216:Toll-Like Receptor 6 / Q000378:metabolism*; D051217:Toll-Like Receptor 9 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: C408982:CPG-oligonucleotide; D004269:DNA, Bacterial; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D051195:Toll-Like Receptor 2; D051216:Toll-Like Receptor 6; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12; D007371:Interferon-gamma; D020928:Mitogen-Activated Protein Kinases
keywords: bacterial DNA; cell signaling; cytokine