Project description:Mucosal immunization and mucosal 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 mucosal IgA responses following mucosal vaccination remain poorly understood. It is also currently debatable whether mucosal vaccination is still warranted given that most individuals in developed countries have established a hybrid immunity from vaccination and infection. Here we characterized respiratory mucosal immune responses after SARS-CoV-2 infection, vaccination or both in humans. We found that hybrid immunity resulted in moderately increased mucosal IgA and neutralizing antibody responses compared to infection or vaccination alone. However, a direct comparison of hybrid immunity and a mucosal adenovirus-based booster vaccination in animal models revealed that respiratory booster immunization elicited markedly stronger and more durable mucosal IgA, T cell response, and protective immunity against SARS-CoV-2, supporting the promise of respiratory mucosal vaccination. Mechanistically, we found that mucosal booster immunization induced local IgA-secreting cells in the respiratory mucosa, aided by pulmonary CD4+ T cells in situ. Strikingly, local IL-21-producing Blimp-1+ Th1 effector cells were critical in mediating the CD4+ T cell help for IgA production. Furthermore, lung macrophages were important for this mucosal IgA response via the production of TGF-β. Consequently, Spike mRNA coated with pulmonary surfactant (PS) containing liposomes, rationally designed to target lung macrophages, elicits a stronger mucosal IgA response. Collectively, 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.
Project description:Mucosal immunization and mucosal 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 mucosal IgA responses following mucosal vaccination remain poorly understood. It is also currently debatable whether mucosal vaccination is still warranted given that most individuals in developed countries have established a hybrid immunity from vaccination and infection. Here we characterized respiratory mucosal immune responses after SARS-CoV-2 infection, vaccination or both in humans. We found that hybrid immunity resulted in moderately increased mucosal IgA and neutralizing antibody responses compared to infection or vaccination alone. However, a direct comparison of hybrid immunity and a mucosal adenovirus-based booster vaccination in animal models revealed that respiratory booster immunization elicited markedly stronger and more durable mucosal IgA, T cell response, and protective immunity against SARS-CoV-2, supporting the promise of respiratory mucosal vaccination. Mechanistically, we found that mucosal booster immunization induced local IgA-secreting cells in the respiratory mucosa, aided by pulmonary CD4+ T cells in situ. Strikingly, local IL-21-producing Blimp-1+ Th1 effector cells were critical in mediating the CD4+ T cell help for IgA production. Furthermore, lung macrophages were important for this mucosal IgA response via the production of TGF-β. Consequently, Spike mRNA coated with pulmonary surfactant (PS) containing liposomes, rationally designed to target lung macrophages, elicits a stronger mucosal IgA response. Collectively, 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.
Project description:Despite remarkable progress in the development and authorization of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a need to validate vaccine platforms for broader application. The current intramuscular vaccines are designed to elicit systemic immunity without conferring mucosal immunity in the nasal compartment, which is the first barrier that SARS-CoV-2 virus breaches before dissemination to the lung. We report the development of an intranasal subunit vaccine that uses lyophilized spike protein and liposomal STING agonist as an adjuvant. This vaccine induces systemic neutralizing antibodies, IgA in the lung and nasal compartments, and T-cell responses in the lung of mice. Single-cell RNA sequencing confirmed the coordinated activation of T/B-cell responses in a germinal center-like manner within the nasal-associated lymphoid tissues, confirming its role as an inductive site to enable durable immunity. The ability to elicit immunity in the respiratory tract can prevent the establishment of infection in individuals and prevent disease transmission.
Project description:Respiratory tract vaccination has an advantage of needle-free delivery and induction of mucosal immune response in the portal of SARS-CoV-2 entry. We utilized human parainfluenza virus type 3 vector to generate constructs expressing the full spike (S) protein of SARS-CoV-2, its S1 subunit, or the receptor-binding domain, and tested them in hamsters as single-dose intranasal vaccines. The construct bearing full-length S induced high titers of neutralizing antibodies specific to S protein domains critical to the protein functions. Robust tissue-resident T cell responses in the lungs were also induced, which represent an additional barrier to infection and should be less sensitive than the antibody responses to mutations present in SARS-CoV-2 variants. Following SARS-CoV-2 challenge, animals were protected from the disease and detectable viral replication. Vaccination prevented induction of gene pathways associated with inflammation. These results indicate advantages of respiratory vaccination against COVID-19 and inform the design of mucosal SARS-CoV-2 vaccines.
Project description:Intranasal vaccines can prime or recruit to the respiratory epithelium mucosal immune cells capable of preventing transmission of SARS-CoV-2. We found that a single intranasal dose of serotype 5-based adenoviral vectors expressing either the receptor binding domain (Ad5-RBD) or the complete ectodomain (Ad5-S) of the SARS-CoV-2 spike protein was effective in inducing i) secretory and serum anti-spike IgA and IgG, ii) robust SARS-CoV-2-neutralizing activity in the serum and in respiratory secretions, iii) rigorous spike-directed T helper 1 cell/cytotoxic T cell immunity, and iv) protection of wild-type mice from a challenge with the SARS-CoV-2 beta variant. Our data confirm and extend previous studies reporting promising preclinical results on vector-based intranasal SARS-CoV-2 vaccination, and support the potential of this approach to elicit mucosal immunity for preventing reinfection and transmission of SARS-CoV-2 more effectively than the currently available vaccines.
Project description:Vaccination against tuberculosis by intradermal Bacillus Calmette-Guérin (BCG) injection saves many lives, supposedly by inducing adaptive immune memory in lymphocytes. Epidemiologically, BCG vaccination is also associated with reduced childhood mortality unrelated to TB, which is attributed to innate immune memory, also termed trained immunity. We recently demonstrated improved protection against tuberculosis infection in highly susceptible rhesus macaques by mucosal BCG vaccination, correlating with a unique local but no peripheral immune profile. Here, we investigated local and peripheral innate immune function after intradermal versus mucosal vaccination with M. bovis BCG or the live attenuated, M. tuberculosis-derived candidate, MTBVAC. The results demonstrate an augmented frequency of trained immunity in monocytes after respiratory mucosal administration of live attenuated mycobacterial vaccines compared to intradermal immunization, with MTBVAC being equally potent as BCG. These results provide further support to strategies for improving TB vaccination and, more broadly, modulating innate immunity via mucosal surfaces.
Project description:A longstanding barrier in vaccinology has been the inability to reconcile potent mucosal immune activation with systemic tolerability, hindering adjuvant development for over a century. Here, we present NanoCF501, a nanoparticulate STING agonist engineered with respiratory-tuned, clinically safe polymers, which overcomes this fundamental limitation. When co-administered with a multivalent pan-β-coronavirus subunit vaccine, NanoCF501 at 1/20th the systemic adjuvant dose elicits coordinated mucosal-systemic immunity, inducing robust and durable cross-protective responses. These include mucosal secretory IgA and tissue-resident memory T cells alongside systemic neutralizing antibodies, memory B cells, and long-lived plasma cells persisting >12 months in murine models. Non-human primates validate the dual-axis mucosal-systemic coupling, while toxicology studies in rats demonstrate more than 18-fold safety margin and undetectable systemic exposure, underscoring translational viability. Mechanistic interrogation via single-cell transcriptomics reveals that NanoCF501 drives STING-dependent innate immune activation, orchestrating broad transcriptional reprogramming in lung antigen-presenting cells and efficient priming of adaptive T and B cell responses. Notably, NanoCF501 converts conventional quadrivalent influenza subunit vaccines into mucosal immunogenic formulations, demonstrating platform versatility. By integrating rational nanocarrier design with innate immune targeting, this work establishes a universal mucosal vaccination strategy with broad implications for pandemic preparedness and mucosal vaccinology.
Project description:A Single Intranasal Vaccination with a Rationally Attenuated SARS-CoV-2 Elicits Strong Humoral Immune Response and Is Protective in Syrian Hamsters