RNA microarray-based comparision of innate immune phenotypes between human macrophages stimulated with two BCG strains

Currently, the only available vaccine against tuberculosis is Mycobacterium bovis Bacille Calmette-Guérin (BCG). Pulmonary tuberculosis protection provided by the vaccine varies depending on the strain, the patient’s age, and the evaluated population. Although the adaptive immune responses induced by different BCG strains have been widely studied, little conclusive data is available regarding innate immune responses, especially in macrophages. Here, we aimed to characterize the innate immune responses of human THP-1-derived macrophages at the transcriptional level following a challenge with either the BCG Mexico or Phipps strains. After a brief in vitro characterization of the bacterial strains and the innate immune responses, including nitric oxide production and cytokine profiles, we analyzed the mRNA expression patterns and performed pathway enrichment analysis using RNA microarrays. Our results showed that multiple biological processes were enriched, especially those associated with innate inflammatory and antimicrobial responses, including tumor necrosis factor (TNF)-α, type I interferon (IFN), and IFN-. These findings indicated the pro-inflammatory stimulation of macrophages induced by both BCG strains, at the cytokine level and in terms of gene expression. Our results demonstrated that both strains activated the innate immune response, with better modulation induced by BCG Phipps. The total RNA of 9 cultures of macrophage derived from THP-1, 3 biological replicates of macrophages infected with BCG Mexico, 3 biological replicas of macrophages infected with BCG Phipps and 3 biological replicas of macrophages derived from THP-1 non infected as a negative control group.