Hyaluronic acid-based dissolving microneedles regulate antigen release and route-dependent immunogenicity of...

Biodegradable polymer-based dissolving microneedles (DMNs) are a promising platform for vaccine delivery. However, their ability to elicit protective systemic and mucosal immunity varies depending on the delivery route. In this study, recombinant adenovirus encoding nucleoprotein (rAd-ANP) was incorporated into HA-based DMNs (rAd-MNs) to evaluate the route-specific immunogenicity of TDMN and sublingual DMN (SLDMN). Despite equivalent dose insertion of rAd-MN, SLDMN demonstrated significantly stronger mucosal and systemic immune responses than those of TDMN, including enhanced immunoglobulin A production and tissue-resident memory T-cell formation in the lungs. Specifically, SLDMN induced 8.7-fold higher anti-PR8 IgG titers, 2.2-fold highter IgA responses, and selectively promoted lung T_RM formation (about 3% of total T cells), whereas T_RM were minimal or undetectable following TDMN administration. These differences were associated with the anatomical and physiological features of sublingual tissue, which facilitated rapid HA matrix dissolution, burst antigen release, and efficient vector uptake. Furthermore, the HA-based solid-state matrix provided superior storage stability under elevated temperatures and freeze-thaw conditions compared with liquid formulations of rAd-ANP. This study emphasizes that DMN vaccine performance is determined by the interplay of polymer dissolution behavior and tissue environment, and highlights SLDMN as a promising strategy for inducing protective immunity against respiratory infections.