Lipids as Activators of Innate Immunity in Peptide Vaccine Delivery

Abstract

Background: Innate immune system plays an important role in pathogen detection and the recognition of vaccines, mainly through pattern recognition receptors (PRRs) that identify pathogen components (danger signals). One of the typically recognised bacterial components are lipids in conjugation with peptides, proteins and saccharides. Lipidic compounds are readily recognised by the immune system, and thus are ideal candidates for peptide- based vaccine delivery. Thus, bacterial or synthetic lipids mixed with, or conjugated to, antigens have shown adjuvant properties. These systems have many advantages over traditional adjuvants, including low toxicity and good efficacy for stimulating mucosal and systemic immune responses. Methods: The most recent literature on the role of lipids in stimulation of immune responses was selected for this review. The vast majority of reviewed papers were published in the last decade. Older but significant findings are also cited. Results: This review focuses on the development of lipopeptide vaccine systems including application of palmitic acid, bacterial lipopeptides, glycolipids and the lipid core peptide and their routes of administration. The use of liposomes as a delivery system that incorporates lipopeptides is discussed. The review also includes a brief description of immune system in relation to vaccinology and discussion on vaccine delivery routes. Conclusion: Lipids and their conjugates are an ideal frontrunner in the development of safe and efficient vaccines for different immunisation routes.