Modeling Mycobacterium tuberculosis pathogenesis in lung epithelial organoids reveals strain-specific host responses...

Emerging studies have identified alveolar epithelial cells as a conducive niche for Mycobacterium tuberculosis (Mtb) replication and spread during early infection. However, the host-pathogen interactions and intercellular crosstalk within the lung epithelial microenvironment remain inadequately understood. Here, we developed a lung epithelial organoid coculture model and exposed it to the virulent H37Rv strain or the avirulent Bacillus Calmette-Guérin (BCG) strain to investigate tuberculosis (TB) pathogenesis. Transcriptomic analyses revealed that Mtb infection markedly alters cell death patterns in organoids and modulates signal transduction pathways in peripheral blood mononuclear cells (PBMCs). Western blot indicates the H37Rv strain induced ferroptosis, autophagy, and apoptosis while suppressing necroptosis in organoids. In contrast, BCG predominantly enhanced autophagy. PBMCs also exhibited strain-specific responses, with BCG strongly activating the Hippo and Notch signaling pathways, whereas H37Rv primarily engaged the tumor necrosis factor (TNF) signaling pathway. Furthermore, Mtb significantly reshaped the paracrine and autocrine signaling dynamics between PBMCs and organoids. NicheNet network analysis identified TNFSF15 and brain-derived neurotrophic factor (BDNF), induced by H37Rv, as key mediators. Experimentally, overexpression of TNFSF15 and BDNF suggested that TNFSF15 from organoids promoted BDNF expression in PBMCs via paracrine signaling. In turn, BDNF from PBMCs then inhibited ferroptosis in organoids, contributing to restrict Mtb growth. Overall, our study provides a conceptual framework for understanding the mechanisms of TB pathogenesis within alveolar epithelial cells and offers valuable insights to prevent and control TB transmission in humans.