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Journal of Immunology Research
Volume 2016 (2016), Article ID 4048235, 17 pages
http://dx.doi.org/10.1155/2016/4048235
Research Article

Low Dose BCG Infection as a Model for Macrophage Activation Maintaining Cell Viability

1Department of Pathology and Immunology, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland
2Laboratory of Integrative Immunology, National Institute of Respiratory Diseases “Ismael Cosio Villegas”, Mexico City, Mexico
3Department of Cell Physiology and Metabolism, Centre Medical Universitaire (CMU), Faculty of Medicine, University of Geneva, Geneva, Switzerland

Received 18 May 2016; Revised 26 August 2016; Accepted 15 September 2016

Academic Editor: Ethan M. Shevach

Copyright © 2016 Leslie Chávez-Galán et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mycobacterium bovis BCG, the current vaccine against tuberculosis, is ingested by macrophages promoting the development of effector functions including cell death and microbicidal mechanisms. Despite accumulating reports on M. 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.