Lung Organoids from Human Embryonic Stem Cells to Investigate Pneumococcal Serotype 23F that does not Infect Mouse

Streptococcus pneumoniae (S. pneumoniae, Pneumococcus) is a predominant pathogen in community-acquired pneumonia.Infection animal models using certain pneumococcal serotypes are well established, but some serotypes, such as ST14 and ST23F, exhibit low or negligible infectivity in mouse models, posing challenges for the development of comprehensive pneumococcal vaccines.In this study, we developed human lung organoids (hLOs) derived from human embryonic stem cells (hESCs) to model pneumococcal infection.hLOs were microinjected with serotype ST23F to assess its infective potential compared with ST4.Our results demonstrate that ST23F successfully colonizes and invades the epithelial cells of hLOs, triggering significant inflammatory responses.This response was quantitatively comparable to that induced by the highly virulent serotype ST4 in mouse models.This organoid-based infection model provides a viable and effective platform for studying pneumococcal serotypes that are inadequately represented in traditional mouse models.Furthermore, it underscores the potential utility of hLOs in the preclinical evaluation of novel multivalent pneumococcal conjugate vaccines, addressing serotypes with historically low virulence in animal models.