A Key Role of CD8+ T Cells in Controlling of Tuberculosis Infection

Recombinant BCG vaccine expressing multistage antigens of Mycobacterium tuberculosis provides long-term immunity against tuberculosis in BALB/c mice

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) persistently kills nearly 1.5 million lives per year in the world, whereas the only licensed TB vaccine BCG exhibits unsatisfactory efficacy in adults. Taking BCG as a vehicle to express Mtb antigens is a promising way to enhance its efficacy against Mtb infection. In this study, the immune efficacy of recombination BCG (rBCG-ECD003) expressing specific antigens ESAT-6, CFP-10, and nDnaK was evaluated at different time points after immunizing BALB/c mice. The results revealed that rBCG-ECD003 induced multiple Th1 cytokine secretion including IFN-γ, TNF-α, IL-2, and IL-12 when compared to the parental BCG. Under the action of PPD or ECD003, rBCG-ECD003 immunization resulted in a significant increase in the proportion of IL-2+ and IFN-γ+IL-2+ CD4+T cells. Importantly, rBCG-ECD003 induced a stronger long-term humoral immune response without compromising the safety of the parental BCG vaccine. By means of the protective efficacy assay in vitro, rBCG-ECD003 showed a greater capacity to inhibit Mtb growth in the long term. Collectively, these features of rBCG-ECD003 indicate long-term protection and the promising effect of controlling Mtb infection.

Mycobacterium tuberculosis Biofilms: Immune Responses, Role in TB Pathology, and Potential Treatment

Tuberculosis (TB) is a major public health problem worldwide, and the burden of drug-resistant TB is rapidly increasing. Although there are literatures about the Mtb biofilms, their impact on immune responses has not yet been summarized. This review article provides recent knowledge on Mycobacterium tuberculosis (Mtb) biofilm-immunity interactions, their importance in pulmonary TB pathology, and immune-based therapy targeting Mtb biofilms. Pellicle/biofilm formation in Mtb contributes to drug resistance, persistence, chronicity, surface attachment, transfer of resistance genes, and modulation of the immune response, including reduced complement activation, changes in the expression of antigenic proteins, enhanced activation of T-lymphocytes, elevated local IFNγ+ T cells, and strong antibody production. The combination of anti-TB drugs and anti-biofilm agents has recently become an effective strategy to improve TB treatment. Additionally, immune-targeted therapy and biofilm-based vaccines are crucial for TB prevention.