A New aspect of the pathology of brain tuberculosis: Mycobacterium tuberculosis infects and alters human neural progenitor cells

Abstract

Brain tuberculosis remains associated with high mortality, and many survivors exhibit cognitive impairments. Progress in understanding the disease is hindered by the lack of human models. In this study, human neural organoids were infected, revealing that a subpopulation of neural progenitor cells (NPCs) is directly infected by apoptotic cell receptors expressed by NPCs, mediating bacterial uptake. Phagocytosed bacteria were localized in late endosomes, lysosomes, and the cytoplasm. Cytoplasmic bacteria frequently formed cords, indicating limited control of bacterial expansion. Immunostaining demonstrated that infected NPCs produce a type I interferon (IFN) response, corroborated by increased expression of type I IFN and IFN-regulated genes detected by RNA sequencing. Pathways related to innate immune response, cell death, and proliferation were also activated following Mycobacterium tuberculosis (Mtb) uptake by NPCs. The addition of color-coded microglia and monocytes to 3D neural organoids and NPCs revealed cross-infection of NPCs and other phagocytes by Mtb, suggesting a mechanism by which NPCs may access the bacteria. Infection of NPCs resulted in increased cell death, inhibition of neural differentiation, and reduced proliferation, effects that were partially mitigated by anti-IFN treatment. Differentiated neurons were not infected. These findings indicate that brain organoids and NPC-based in vitro platforms provide a novel approach for studying brain tuberculosis. Decreased NPC function may contribute to brain tuberculosis-induced cognitive disease.