Marcantonio Endrei, Burger Allexa D, Chang Kelly H, Hoffmann Fukun W, Fu Yuanyuan, Khadka Vedbar S, Smagghe Benoit J, Deng Youping, Hoffmann Peter R, Prisic Sladjana
School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA.
Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA.
Infect Immun. 2025 Mar 11;93(3):e0057824. doi: 10.1128/iai.00578-24. Epub 2025 Feb 4.
Tuberculosis (TB) is notoriously difficult to treat, likely due to the complex host-pathogen interactions driven by pathogen heterogeneity. An understudied area of TB pathogenesis is host responses to bacteria (Mtb) that are limited in zinc ions. This distinct population resides in necrotic granulomas and sputum and could be the key player in tuberculosis pathogenicity. In this study, we tested the hypothesis that macrophages differentiate between Mtb grown under zinc limitation or in the standard zinc-replete medium. Using several macrophage infection models, such as murine RAW 264.7 and murine bone marrow-derived macrophages (BMDMs), as well as human THP-1-derived macrophages, we show that macrophages infected with zinc-limited Mtb have increased bacterial burden compared with macrophages infected with zinc-replete Mtb. We further demonstrate that macrophage infection with zinc-limited Mtb trigger higher production of reactive oxygen species (ROS) and cause more macrophage death. Furthermore, the increased ROS production is linked to the increased phagocytosis of zinc-limited Mtb, whereas cell death is not. Finally, transcriptional analysis of RAW 264.7 macrophages demonstrates that macrophages have more robust pro-inflammatory responses when infected with zinc-limited Mtb than zinc-replete Mtb. Together, our findings suggest that Mtb's access to zinc affects their interaction with macrophages and that zinc-limited Mtb may be influencing TB progression. Therefore, zinc availability in bacterial growth medium should be considered in TB drug and vaccine developments.
结核病（TB） notoriously难以治疗，这可能是由于病原体异质性驱动的复杂宿主-病原体相互作用所致。结核病发病机制中一个研究不足的领域是宿主对锌离子受限的细菌（结核分枝杆菌，Mtb）的反应。这个独特的群体存在于坏死性肉芽肿和痰液中，可能是结核病致病性的关键因素。在本研究中，我们检验了一个假设，即巨噬细胞能够区分在锌限制条件下生长的Mtb和在标准锌充足培养基中生长的Mtb。使用几种巨噬细胞感染模型，如小鼠RAW 264.7细胞和小鼠骨髓来源的巨噬细胞（BMDMs），以及人THP-1来源的巨噬细胞，我们发现，与感染锌充足Mtb的巨噬细胞相比，感染锌限制Mtb的巨噬细胞的细菌载量增加。我们进一步证明，感染锌限制Mtb的巨噬细胞会引发更高水平的活性氧（ROS）产生，并导致更多的巨噬细胞死亡。此外，ROS产生的增加与锌限制Mtb吞噬作用的增强有关，而细胞死亡则与之无关。最后，对RAW 264.7巨噬细胞的转录分析表明，与感染锌充足Mtb相比，感染锌限制Mtb的巨噬细胞具有更强的促炎反应。总之，我们的研究结果表明，Mtb获取锌的情况会影响它们与巨噬细胞的相互作用，并且锌限制的Mtb可能会影响结核病的进展。因此，在结核病药物和疫苗开发中应考虑细菌生长培养基中的锌可用性。
