Squalene nanoemulsion reinforces mucosal and immunological fingerprints following intravaginal delivery

• Main Authors: Hui-Min Ho, Chiung-Yi Huang, Yu-Jhen Cheng, I-Hua Chen, Shih-Jen Liu, Chung-Hsiung Huang, Ming-Hsi Huang
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Biomedicine & Pharmacotherapy
• Subjects: Mucosal adjuvant; Nanoemulsion; Squalene; Vaccine; Vaginal delivery
• Online Access: http://www.sciencedirect.com/science/article/pii/S0753332221005813

This study describes the assessment of mucosal adjuvant activity of a squalene-based nanoemulsion (SQ@NE) following intravaginal delivery in mice. After immunization, a high level of recruitment of CD11b/c+ granulocytes and F4/80+ macrophages was observed in the vaginal mucosal tissues of the mice immunized with a model protein ovalbumin (OVA) formulated with SQ@NE, and then downstream regulated the expression of MHC II and costimulatory molecules CD40 and CD86 on CD11c+ cells harvested from the associated draining lymph node. With respect to cytotoxic T lymphocyte immunity, the mice immunized with SQ@NE-formulated OVA elicited a high population of OVA-specific CD8+ cells in the spleen and increased the secretion of IFN-γ, IL-2 and IL-17 from OVA-restimulated splenocytes compared with those immunized with OVA alone. By studying in vivo fluorescence imaging and B-cell immunoassays, we discovered how SQ@NE prolongs the retention of antigen depots at the mucosal membrane of the immune inductive site and allows them to properly drive the production of antibodies. The data demonstrated that SQ@NE prolonged fluorescence-labeled OVA retention at the genital tract and augmented the production of OVA-specific IgG in sera and IgA in vaginal washes. These results indicate that SQ@NE is a promising vaginal adjuvant for the induction of both mucosal and systemic immune responses, a feature that provides implications for the development of a mucosal vaccine against genital infections and sexually transmitted diseases.