LprG and PE_PGRS33 Mycobacterium tuberculosis virulence factors induce differential mitochondrial dynamics in macrophages.

The interaction of a pathogen with its host cell takes place at different levels, including the bioenergetics adaptation of both the pathogen and the host cell in the course of an infection. In this regard, Mycobacterium tuberculosis infection of macrophages induces mitochondrial membrane potential (Δψm) changes and cytochrome c release, depending on the bacteria strain's virulence, and the mitochondrial dynamics is modified by pathogens, such as Listeria monocytogenes. Here, we investigated whether two M. tuberculosis virulence factors are able to induce distinguishable bioenergetics traits in human monocyte-derived macrophages (MDMs). Results showed that Rv1411c (LprG, p27) induced mitochondrial fission, lowered the cell respiratory rate and modified the kinetics of mitochondrial Ca uptake in response to agonist stimulation. In contrast, Rv1818c (PE_PGRS33) induced mitochondrial fusion, but failed to induce any appreciable effect on cell respiratory rate or mitochondrial Ca uptake. Overall, these results suggest that two different virulence factors from the same pathogen (M. tuberculosis) induce differential effects on mitochondrial dynamics, cell respiration and mitochondrial Ca uptake in MDMs. The timing of differential mitochondrial activity could ultimately determine the outcome of host-pathogen interactions.