Prior Bacillus Calmette-Guérin (BCG) vaccination ameliorates the pathogenesis of Type 2 diabetes mellitus mice infected with Mycobacterium tuberculosis

Abstract Previously, we found experimentally induced type 2 diabetes mellitus (T2DM) mice are highly susceptible to Mycobacterium tuberculosis (Mtb) infection. In the present study, we determined whether prior BCG vaccination has any effect on the susceptibility of T2DM mice infected with Mtb. C57BL/6 mice were vaccinated with BCG or treated with PBS, three months later some mice were induced with T2DM and after another month fifty percent of all groups of mice were challenged with Mtb. All Mtb infected T2DM mice and 40% of uninfected T2DM mice died within 10 months. In contrast, only 40% of Mtb infected BCG vaccinated T2DM mice and 20% of uninfected BCG vaccinated T2DM mice died. Lung bacterial burden was significantly less in Mtb infected BCG vaccinated T2DM mice compared to PBS treated Mtb infected mice. Pro and anti-inflammatory cytokine levels were significantly high in the lungs of Mtb infected BCG vaccinated T2DM mice compared to all other groups of vaccinated and PBS treated mice infected with Mtb. Our findings suggest that prior BCG vaccination protects Mtb infected mice from T2DM induced pathogenesis. Studies are underway to determine the BCG induced mechanism/s those protect T2DM mice challenged with Mtb.