Sphingomyelin biosynthesis is essential for phagocytic signaling during Mycobacterium tuberculosis host cell entry

Mycobacterium tuberculosis (Mtb) invades alveolar macrophages through phagocytosis to establish infection and cause disease. The molecular mechanisms underlying Mtb entry are still poorly understood. Here, we report that an intact sphingolipid biosynthetic pathway is essential for the uptake of Mtb across multiple phagocytic cell types without affecting other forms of endocytosis. Disrupting sphingolipid production prevents the removal of the inhibitory phosphatase CD45 from the nascent phagosome, a critical step in the progression of phagocytosis. We also show that blocking sphingolipid biosynthesis impairs activation of Rho GTPases, actin dynamics and phosphoinositide turnover at the host-pathogen contact site. Moreover, production of sphingomyelin, not glycosphingolipids, is critical for the uptake of Mtb. Together, our data provide mechanistic insights regarding how Mtb exploits sphingomyelin metabolism to enter host cells, representing a potential avenue for designing host-directed therapeutics against tuberculosis.