Multiplication of Legionella pneumophila in HeLa Cells in the Presence of Cytoskeleton and Metabolic Inhibitors

Abstract

A study has been carried out on the action of cytoskeleton and metabolic inhibitors on intracellular multiplication in HeLa cells of a virulent strain of Legionella pneumophila serogroup 6. The effects of the substances were separately tested on both penetration and intracellular multiplication of L. pneumophila. Only cytochalasin A and 2-deoxy-D-glucose (2dG) affected bacterial internalisation, whereas intracellular multiplication was inhibited by cytochalasins A, B, C, D and J (D being the most active) and by 2dG with a dose-response effect. The action of 2dG was counteracted by 50 mm glucose. Experiments carried out with cytochalasin D and a rhodamine-phalloidin conjugate showed the involvement of cytoskeletal elements in intracellular multiplication of Legionella; compounds acting on microtubules had no effect.

Legionella pneumophila Is Directly Sensitive to 2-Deoxyglucose-Phosphate via Its UhpC Transporter but Is Indifferent to Shifts in Host Cell Glycolytic Metabolism

“…Because L. pneumophila is able to replicate in glycolytic macrophages, we initially hypothesized that L. pneumophila was taking advantage of macrophage glycolysis during intracellular replication. This hypothesis was supported by our result showing that the glycolysis inhibitor 2DG blocked L. pneumophila replication in BMMs, an effect that has been reported in other studies (22)(23)(24)(25). However, other experiments in which we inhibited host macrophage glycolysis had no effect on intracellular L. pneumophila replication and demonstrated that the inhibitory effect of 2DG on intracellular L. pneumophila was unlikely via induction of a shift in host cell metabolism.…”

“…Here, we report that BMMs infected with L. pneumophila display a characteristic increase in glycolysis, similar to observations noted in a recent report (22). We speculated that increased host cell glycolysis may benefit L. pneumophila because the glycolysis inhibitor 2-deoxyglucose (2DG) has been reported to block L. pneumophila replication in mammalian cells, though the mechanism(s) underlying this effect remains obscure (23)(24)(25). It has been suggested that 2DG acts on host cells during L. pneumophila infection by modulating autophagy, inhibiting uptake of bacteria by interfering with phagocytosis, or altering the intracellular metabolic environment (22)(23)(24)(25).…”

“…We speculated that increased host cell glycolysis may benefit L. pneumophila because the glycolysis inhibitor 2-deoxyglucose (2DG) has been reported to block L. pneumophila replication in mammalian cells, though the mechanism(s) underlying this effect remains obscure (23)(24)(25). It has been suggested that 2DG acts on host cells during L. pneumophila infection by modulating autophagy, inhibiting uptake of bacteria by interfering with phagocytosis, or altering the intracellular metabolic environment (22)(23)(24)(25). Consistent with the notion that 2DG acts via an effect on host cells, the inhibitory effect of 2DG on L. pneumophila is specific to infection of mammalian cells, since 2DG has no effect on bacterial replication in broth (23), and we observed that 2DG does not inhibit bacterial growth in protozoan host cells.…”

Ultrastructural Analysis of Differentiation in Legionella pneumophila

“…pneumophila growth phases in HeLa cells. Using previously reported morphological and physiological responses of HeLa cells to L. pneumophila infection (17,29,30), we divided the intracellular growth cycle shown in Fig. 1 into four phases, centered on the well-defined event of bacterial replication.…”