Current status and prospects of mucosal immunity-based vaccine adjuvants and delivery systems for gastrointestinal vaccines

Vaccines represent the most cost-effective and efficacious approach for preventing gastrointestinal infections, and adjuvants play a pivotal role in enhancing and modulating immune responses. In this article, we summarize the mechanisms, advantages, and limitations of molecular adjuvants that induce gastrointestinal mucosal immune responses, as well as of delivery systems with dual adjuvant and carrier functions. We also analyze the principal challenges encountered in the development of such adjuvants, encompassing issues related to safety, efficacy, and adaptability. Furthermore, this article provides perspectives on future research directions for mucosal immunity-based adjuvants for gastrointestinal vaccines, including design of programmed adjuvants targeting specific gastrointestinal receptors, composite strategies integrating delivery systems with adjuvants, and adjuvant optimization tailored for special populations.