Research Scientist Univ. of Virginia Sch. of Med. Charlottesville, Virginia, United States
Disclosure(s):
Jinyi Tang, PhD: No relevant disclosure to display
Introduction/Rationale: Mucosal immunization and respiratory IgA offer significant promise in protecting against airborne pathogens, including SARS-CoV-2. However, the conditions and mechanisms that lead to the robust induction of respiratory IgA responses following mucosal vaccination remain poorly understood.
Methods: In this project, we established SARS-CoV-2 breakthrough infection and mucosal adenovirus-based booster vaccination models. Using genetic mouse models and various in vivo and in vitro blockade or depletion approaches, we further investigated the mechanisms regulating respiratory IgA responses.
Results: Here we found that a mucosal adenovirus-based booster vaccination in mouse models revealed that respiratory booster immunization elicited markedly stronger and more durable respiratory IgA, T cell response, and protective immunity against SARS-CoV-2, supporting the promise of respiratory mucosal vaccination. Mechanistically, we identified that local CD4⁺ T cells support respiratory IgA production by promoting IgA⁺ B cell class switching, proliferation, and survival in situ. This T cell help depended on interactions between local Blimp-1⁺ T-bet⁺ Th1 cells and B cells, mediated through ICOS/CD40L/MHC-II engagement and IL-21 signaling. Furthermore, lung macrophages contributed to the mucosal IgA response via TGF-β production. Consequently, mucosal administration of SARS-CoV-2 Spike-encoding mRNA encapsulated in pulmonary surfactant (PS)- incorporated lipid nanoparticles designed to target lung macrophages elicited a stronger mucosal IgA response.
Conclusion: Our results uncover a local cellular network supporting enhanced mucosal IgA responses, with implications for the development of optimal mucosal immunization strategies against SARS-CoV-2 and other respiratory pathogens such as H5N1 influenza.
