Phagocytosis is inhibited by autophagic induction in murine macrophages

Recent studies have demonstrated that communication takes place between the autophagic and phagocytic pathways, indicating that the convergence of these two pathways plays an important role in the innate immune response against intracellular microbes. The present study investigated the effect of autophagic induction on the phagocytic capacity of murine macrophages. Autophagy induced by physiological and pharmacological means was shown to reduce the phagocytic capacity of murine macrophages, regardless of cell origin or the nature of the phagocytosed particles themselves. This autophagic inhibitory effect on phagocytosis was shown to be an early and reversible event that results in no loss of cell viability. Furthermore, the data presented herein demonstrate that the induction of autophagy does not affect a macrophage’s capacity to recognize and bind to particles, indicating that autophagy does not inhibit the particle recognition process, even though particle internalization is suppressed. The findings herein support the notion that phagocytosis and autophagy may be interdependent and complementary processes.

Research highlights
► Yeast phagocytosis was reduced in macrophages incubated in autophagic conditions.
► The autophagic process itself triggers the inhibitory effect on the phagocytosis.
► Autophagy inhibits phagocytosis by professional phagocytes in a generalized manner.
► Autophagy does not influence particle–receptor interactions during phagocytosis.