Peptide-free Synthetic Nicotine Vaccine Candidates with α-Galactosylceramide as Adjuvant

Abstract

Peptides are generally needed as T-helper epitopes in nicotine vaccines to induce effective antibody responses, but the highly polymorphic property of major histocompatibility complex (MHC) molecules may limit opportunities of B cell to receive CD4+ T-cell help. Invariant natural killer T (iNKT) cells recognize lipid antigens presented by the nonpolymorphic CD1d molecule that is conserved in mammals to a great extent. iNKT cells also display some similar functions to conventional CD4+ T-helper cells, especially they license dendritic cells stimulate antibody isotype switching by B cells. Herein, α-galactosylceramide (αGalCer), a classical iNKT cell agonist, serves as an adjuvant in synthetic nicotine vaccine candidates absent of peptide or protein. Our study reveals that αGalCer displays better adjuvant activity than Pam3CSK4 (a commonly used lipopeptide TLR agonist). Remarkably, the covalent linker between the nicotine hapten and αGalCer is not critical. Self-assembly of the lipid-tailed nicotine and αGalCer into the liposome represents a structurally simple but immunologically effective way to develop nicotine vaccines. This is the first time to introduce the iNKT cell agonist as an adjuvant to an antidrug vaccine. This discovery may contribute to improving the efficacy of clinical candidate nicotine vaccines in the future.

Liposomal Antitumor Vaccines Targeting Mucin 1 Elicit a Lipid‐Dependent Immunodominant Response

“…Secretion of the cytokine IL-4 can polarizeTlymphocytes towardthe Th2type, and elicit pre-dominantly IgG1 antibodies. IFN-g,a saTh1 cytokine, participates in macrophage activation and induces mainly IgG2a and IgG3 antibodies.S imilar to our previous study, [11] the groups administered aGalCer vaccines exhibited significantly higher levels of both IL-4 (up to 10-fold) and IFN-g (up to 40-fold) than the groups administered other adjuvants (Pam 3 CSK 4 , bGalCer, Freund'sadjuvant)o rM UC1 antigen alone.…”

“…[8] This unique property prompted scientists to developp otent vaccines bearing the iNKT cell agonist a-galactosylceramide (aGalCer) or its analogues as adjuvants. [9][10][11][12] In our previousw ork, at wo-component cancerv accine was constructed with the NKT cell agonist aGalCer and the tumorassociated carbohydrate antigen STn, which showed remarkable efficacya nd induced antibody class switching from IgM to STn-specific IgG in the absence of aT he pitope peptide. [10] Recently,w ed eveloped as ynthetic anti-nicotine vaccine to promote smoking cessation, the vaccine comprising am ixture of lipid-tailed nicotine and aGalCer triggered the production of effective antibodies against anicotinehapten.…”

“…[10] Recently,w ed eveloped as ynthetic anti-nicotine vaccine to promote smoking cessation, the vaccine comprising am ixture of lipid-tailed nicotine and aGalCer triggered the production of effective antibodies against anicotinehapten. [11,12] In view of these findings and to increase the immunogenicity of MUC1 antigens, herein we investigated the relationships between lipidation of hydrophilic MUC1 antigensa nd the effectiveness of vaccines. We constructed liposomal vaccines targeting MUC1, which are composed of synthetic lipid-tailed MUC1 glycopeptides as B-cell epitopes and al ipid-compound of the NKT agonist aGalCer or the TLR1/2a gonist Pam 3 CSK 4 [11,13] as an immunostimulanta djuvant(Scheme 1).…”

“…[11,12] In view of these findings and to increase the immunogenicity of MUC1 antigens, herein we investigated the relationships between lipidation of hydrophilic MUC1 antigensa nd the effectiveness of vaccines. We constructed liposomal vaccines targeting MUC1, which are composed of synthetic lipid-tailed MUC1 glycopeptides as B-cell epitopes and al ipid-compound of the NKT agonist aGalCer or the TLR1/2a gonist Pam 3 CSK 4 [11,13] as an immunostimulanta djuvant(Scheme 1). The extracellular domain of MUC1 consists of numerous tandem repeats (HGVTSAPDTRPAPGSTAPPA), bearing five potential sites of O-glycosylation on serine or threonine, in which the O-glycosylation sites and structures significantly affect the immunogenicity of the glycoprotein.…”

“…[16] Herein, the liposomal vaccinesc omprised the synthetic MUC1 glycopeptide as the antigen, an adjuvant (Scheme 1b), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and cholesterol (in am olarr atio of 10:5:50:40) (Scheme 1c). In addition to aGalCer,t he adjuvants in the control include Pam 3 CSK 4 , bGalCer( aw eakN KT cell agonist), [11] and Freund's adjuvant (using the optimal amount,s ee SI). To obtain the size and dispersion of MUC1 antigens 1-3 after loading on liposomes, dynamic light scattering (DLS) (Figure 1a (3)a ntigensw ith mean diameters of approximately 390 nm (PDI:0 .377) and2 80 nm (PDI:0 .213), respectively,s uggesting that the dipalmitoyl chains attachedt oM UC1 decreased the size of the liposomes.…”