Modeling Bordetella pertussis infection and immunity in human nasal organoids - PROJECT SUMMARY Whooping cough, caused by Bordetella pertussis, has resurged in recent years and remains a significant cause of illness, particularly among infants and young children. Vaccines are available, but they fail to induce long- lasting immunity and to prevent transmission. Controlled human models of pertussis infection have been established recently to understand pathogenesis and identify correlates of protection. These studies, however, are conducted on healthy adults. The steps of bacterial colonization, infection, and shedding in young children, the most vulnerable population, and their capabilities to mount an immune response remain unknown. This proposal aims to establish a novel in vitro model to study pertussis infection and mucosal immunity, as it occurs in the pediatric upper respiratory mucosa, consisting of organoids derived from adenoid and tonsil tissues from children of different ages. Our central hypothesis is that adenoid- and tonsil-derived organoids recapitulate tissue biology and essential features of B. pertussis infection and host mucosal immunity. Two main goals are proposed. In Aim 1, we will characterize pediatric adenoid- and tonsil-derived organoids. The organoid phenotype and functional capabilities will be compared with those of native resected tissue to assess the fidelity and translational value of these models. Tissue-resident immune cells retrieved from fresh tissue will be characterized and added to the organoids to generate autologous immune organoid co-cultures. In Aim 2, we will define infection processes and host response to B. pertussis in the adenoid- and tonsil-derived organoids. Organoids exposed to B. pertussis in a dose- and time-dependent manner will be examined for bacterial invasion, replication, and shedding. Organoids will be co-cultured with innate immune cells and lymphocytes that have been purified from autologous tissue (tissue compatibility). The immunological responses will be examined through analysis of bacterial uptake by phagocytic cells, T and B cell activation, and production of immune markers (cytokines, antibodies). Outcomes from infection and immunity will be compared with clinical findings (pertussis shedding, clinical symptoms, and immune responses at different infection doses) from a controlled human infection model study conducted at Dalhousie University. This application is conceptually and technically innovative and suitable for the high-risk, high-reward R21 mechanism. The research proposed aligns with the NIH priority for studies on human-based models, reducing animal use. This project is also timely, given the resurgence of pertussis cases in recent years. The team’s expertise, substantial evidence supporting the feasibility of the plan proposed, and our access to unique and well-characterized clinical resources assure the success of this proposal. The pediatric nasal organoid model to be studied can have broader applicability, enabling studies with other respiratory pathogens.
