Chitosan enhances nanoparticle delivery from the reproductive tract to target draining lymphoid organs.

To prime adaptive immune responses from the female reproductive tract (FRT), particulate antigens must be transported to draining lymph nodes (dLNs) since there are no local organized lymphoid structures equivalent to those found in the respiratory or gastrointestinal tracts. However, little is known about how to safely and effectively navigate successive barriers to transport such as crossing the epithelium and gaining access to migratory cells and lymphatic drainage that provide entry into dLNs. Here, we demonstrate that intravaginal pre-treatment with chitosan significantly facilitates translocation of nanoparticles (NPs) across the multilayered vaginal epithelium to target dLNs. In addition, chitosan pre-treatment was found to enhance NP associations with immunogenic antigen presenting cells in the vaginal submucosa. These observations indicate that chitosan may have great potential as an adjuvant for both local and systemic protective immunity against viral infections in the FRT.