Curcumin Nanoparticles Enhance Mycobacterium bovis BCG Vaccine Efficacy by Modulating Host Immune Responses

Abstract

Tuberculosis (TB) is one of the deadliest diseases, causing ∼2 million deaths annually worldwide. Mycobacterium bovis bacillus Calmette-Guérin (BCG), the only TB vaccine in common use, is effective against disseminated and meningeal TB in young children but is not effective against adult pulmonary TB. T helper 1 (Th1) cells producing interferon gamma (IFN-γ) and Th17 cells producing interleukin-17 (IL-17) play key roles in host protection against TB, whereas Th2 cells producing IL-4 and regulatory T cells (Tregs) facilitate TB disease progression by inhibiting protective Th1 and Th17 responses. Furthermore, the longevity of vaccine efficacy critically depends on the magnitude of long-lasting central memory T (TCM) cell responses. Hence, immunomodulators that promote TCM responses of the Th1 and Th17 cell lineages may improve BCG vaccine efficacy. Here, we show that curcumin nanoparticles enhance various antigen-presenting cell (APC) functions, including autophagy, costimulatory activity, and the production of inflammatory cytokines and other mediators. We further show that curcumin nanoparticles enhance the capacity of BCG to induce TCM cells of the Th1 and Th17 lineages, which augments host protection against TB infection. Thus, curcumin nanoparticles hold promise for enhancing the efficacy of TB vaccines.