title: IL-10 is required for polarization of macrophages to M2-like phenotype by mycobacterial DnaK (heat shock protein 70).
abstract: Macrophages are key cells in the innate immune system. They phagocytose pathogens and cellular debris, promote inflammation, and have important roles in tumor immunity. Depending on the microenvironment, macrophages can polarize to M1 (inflammatory) or M2 (anti-inflammatory) phenotypes. Extracellular DnaK (the bacterial ortholog of the mammalian Hsp70) from Mycobacterium tuberculosis (Mtb) was described to exert immune modulatory roles in an IL-10 dependent manner. We have previously observed that endotoxin-free DnaK can polarize macrophages to an M2-like phenotype. However, the mechanisms that underlie this polarization need to be further investigated. IL-10 has been described to promote macrophage polarization, so we investigated the involvement of this cytokine in macrophages stimulated with extracellular DnaK. IL-10 was required to induce the expression of M2 markers - Ym1 and Fizz, when macrophages were treated with DnaK. Blockade of IL-10R also impaired DnaK induced polarization, demonstrating the requirement of the IL-10/IL-10R signaling pathway in this polarization. DnaK was able to induce TGF-β mRNA in treated macrophages in an IL-10 dependent manner. However, protein TGF-β could not be detected in culture supernatants. Finally, using an in vivo allogeneic melanoma model, we observed that DnaK-treated macrophages can promote tumor growth in an IL-10-dependent manner. Our results indicate that the IL-10/IL-10R axis is required for DnaK-induced M2-like polarization in murine macrophages.
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Biomedical Research Institute, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90680-001, Brazil.
authors.forename: Rafael L
authors.initials: RL
authors.lastname: Lopes
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Biomedical Research Institute, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90680-001, Brazil.
authors.forename: Thiago J
authors.initials: TJ
authors.lastname: Borges
authors.affiliation: Laboratório de Biologia Celular e Molecular, Unilassale, Canoas, RS 92010-000, Brazil.
authors.forename: Rafael F
authors.initials: RF
authors.lastname: Zanin
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Biomedical Research Institute, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90680-001, Brazil. Electronic address: cbonorino@pucrs.br.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bonorino
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism*; D008262:Macrophage Activation / Q000502:physiology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018832:Molecular Chaperones / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D010587:Phagocytosis / Q000502:physiology; D010641:Phenotype; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C000595121:DnaK protein, Mycobacterium smegmatis; D018840:HSP70 Heat-Shock Proteins; C556062:IL10 protein, mouse; D018832:Molecular Chaperones; D016212:Transforming Growth Factor beta; D016753:Interleukin-10
keywords: Anti-inflammatory; DnaK; M2-phenotype; Macrophage