Systemically inoculated adjuvants stimulate pDC-dependent IgA response in local site

Area of Science:

• Immunology
• Vaccinology
• Respiratory Medicine

Background:

• Local immune stimulation in the respiratory tract is crucial for controlling viral infections.
• The mechanisms underlying non-mucosal adjuvant administration for local immunity are not well understood.

Purpose of the Study:

• To elucidate how non-mucosal adjuvant inoculation stimulates plasmacytoid dendritic cell (pDC)-dependent immunoglobulin (Ig)A responses in the lungs.
• To explore novel mucosal vaccine strategies utilizing systemically administered adjuvants.

Main Methods:

• Systemic inoculation with type 1 interferon (IFN)-inducing adjuvants in mice.
• Analysis of pDC recruitment, activation, and function in the lungs.
• Assessment of IgA production and protection against influenza virus infection.
• Experiments using pDC-depleted and Ifnar1 knockout mice.

Main Results:

• Type 1 IFN induced by systemic adjuvants promotes pDC recruitment to the lungs via CXCL9/10/11 and CXCR3.
• Activated pulmonary pDCs enhance antigen-specific IgA production.
• pDC depletion or Ifnar1 deficiency impairs lung IgA responses.
• Combined systemic adjuvant and intranasal antigen sensitization confers protection against influenza virus.

Conclusions:

• Non-mucosal adjuvant administration can effectively stimulate local lung immunity through a pDC-dependent, type 1 IFN-mediated pathway.
• This study provides a mechanistic basis for developing innovative mucosal vaccine strategies.
• The findings highlight the potential of combining systemic adjuvants with intranasal antigen delivery for respiratory virus protection.