Low Dose BCG Infection as a Model for Macrophage Activation Maintaining Cell Viability.
Mycobacterium bovisBCG, the current vaccine against tuberculosis, is ingested by macrophages promoting the development of effector functions including cell death and microbicidal mechanisms. Despite accumulating reports onM. tuberculosis, mechanisms of BCG/macrophage interaction remain relatively undefined. In vivo, few bacilli are sufficient to establish a mycobacterial infection; however, in vitro studies systematically use high mycobacterium doses. In this study, we analyze macrophage/BCG interactions and microenvironment upon infection with low BCG doses and propose an in vitro model to study cell activation without affecting viability. We show that RAW macrophages infected with BCG at MOI 1 activated higher and sustained levels of proinflammatory cytokines and transcription factors while MOI 0.1 was more efficient for early stimulation of IL-1β, MCP-1, and KC. Both BCG infection doses induced iNOS and NO in a dose-dependent manner and maintained nuclear and mitochondrial structures. Microenvironment generated by MOI 1 induced macrophage proliferation but not MOI 0.1 infection. In conclusion, BCG infection at low dose is an efficient in vitro model to study macrophage/BCG interactions that maintains macrophage viability and mitochondrial structures. This represents a novel model that can be applied to BCG research fields including mycobacterial infections, cancer immunotherapy, and prevention of autoimmunity and allergies.
Department of Pathology and Immunology, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland; Laboratory of Integrative Immunology, National Institute of Respiratory Diseases "Ismael Cosio Villegas", Mexico City, Mexico.
Leslie
L
Chávez-Galán
Department of Pathology and Immunology, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland.
Dominique
D
Vesin
Department of Cell Physiology and Metabolism, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland.
Denis
D
Martinvalet
Department of Pathology and Immunology, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland.
Irene
0000-0002-8656-5568
I
Garcia
D000818:Animals; D002470:Cell Survival; D016207:Cytokines / Q000276:immunology; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D009163:Mycobacterium bovis / Q000276:immunology* / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D000067996:RAW 264.7 Cells
D016207:Cytokines; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse