Physical mixture of a cyclic lipopeptide vaccine induced high titres of opsonic IgG antibodies against group A streptococcus

Self-assembled monovalent lipidated mannose ligand as a standalone nanoadjuvant

Subunit vaccines require an immunostimulant (adjuvant) and/or delivery system to induce immunity. However, currently, available adjuvants are either too dangerous in terms of side effects for human use (experimental adjuvants) or have limited efficacy and applicability. In this study, we examined the capacity of mannose-lipopeptide ligands to enhance the immunogenicity of a vaccine consisting of polyleucine(L15)-antigen conjugates anchored to liposomes. The clinically tested Group A Streptococcus (GAS) B-cell epitope, J8, combined with universal T helper PADRE (P) was used as the antigen. Six distinct mannose ligands were incorporated into neutral liposomes carrying L15PJ8. While induced antibody titers were relatively low, the ligand carrying mannose, glycine/lysine spacer, and two palmitic acids as liposomal membrane anchoring moieties (ligand 3), induced significantly higher IgG titers than non-mannosylated liposomes. The IgG titers were significantly enhanced when positively charged liposomes were employed. Importantly, the produced antibodies were able to kill GAS bacteria. Unexpectedly, the physical mixture of only ligand 3 and PJ8 produced self-assembled nanorods that induced antibody titers as high as those elicited by the lead liposomal formulation and antigen adjuvanted with the potent, but toxic, complete Freund's adjuvant (CFA). Antibodies produced upon immunization with PJ8 + 3 were even more opsonic than those induced by CFA + PJ8. Importantly, in contrast to CFA, ligand 3 did not induce observable adverse reactions or excessive inflammatory responses. Thus, we demonstrated that a mannose ligand, alone, can serve as an effective vaccine nanoadjuvant.

Synthetic Anti-Cocaine Nanoaccine Successfully Prevents Cocaine-Induced Hyperlocomotion

Cocaine is one of the most widely used and increasingly popular illicit psychoactive drugs. Unlike other commonly used substances of abuse, cocaine has no pharmacological therapies to treat addiction or aid in rehabilitation. Immunopharmacology has long been touted as a possible avenue to develop effective anticocaine therapies; however, lack of efficacy and designs which are not consistent with simple large-scale production have hindered vaccine translation. We have designed and synthesized a peptide-based anti-cocaine immunogen which we have shown is capable of inducing physiologically relevant immune responses in mice as part of a self-adjuvanting delivery system or in combination with the human-approved commercial adjuvant MF59. We have demonstrated that immunization with the reported vaccine elicits high titers of anti-cocaine IgG and prevents cocaine-induced hyperlocomotion in an in vivo murine model. This peptide-hapten immunogen along with self-adjuvanting liposomal-based delivery system provides a platform for the development of effective anti-drug vaccines.

Nanotherapeutics with immunoregulatory functions for the treatment of bacterial infection

The advent of drug-resistant pathogens results in the occurrence of stubborn bacterial infections that cannot be treated with traditional antibiotics. Antibacterial immunotherapy by reviving or activating the body's immune system to eliminate pathogenic bacteria has confirmed promising therapeutic strategies in controlling bacterial infections. Subsequent studies found that antimicrobial immunotherapy has its own benefits and limitations, such as avoiding recurrence of infection and autoimmunity-induced side effects. Current studies indicate that the various antibacterial therapeutic strategies inducing immune regulation can achieve superior therapeutic efficacy compared with monotherapy alone. Therefore, summarizing the recent advances in nanomedicine with immunomodulatory functions for combating bacterial infections is necessary. Herein, we briefly introduce the crisis caused by drug-resistant bacteria and the opportunity for antibacterial immunotherapy. Then, immune-involved multimodal antibacterial therapy for the treatment of infectious diseases was systematically summarized. Finally, the prospects and challenges of immune-involved combinational therapy are discussed.

Structure-activity relationship of lipid, cyclic peptide and antigen rearrangement of physically mixed vaccines

Currently there is no approved vaccine to prevent and/or treat group A Streptococcus (GAS) infection. With increasing reports of GAS antibiotic resistance, vaccine adjuvants and targeted delivery systems which induce a strong immune response are a widely acknowledged unmet need. Through extensive structure-activity studies, we investigated a cyclic decapeptide physically mixed with a GAS B cell peptide epitope (J8), a universal T helper epitope (PADRE), and different synthetic lipidic moieties as a conceivable self-adjuvanting GAS vaccine. We explored the structure (orientation)-relationship of the chemically-conjugated B cell epitope and T helper epitope peptide as part of this physically-mixed vaccine. Following in vivo assessment in mice, these cyclic lipopeptide vaccines showed successful induction of J8-specific systemic IgG antibodies when administered subcutaneously without additional adjuvant. Interestingly, an exposed C-terminus of the GAS B cell epitope and a 16-carbon alpha-amino fatty acid lipid was required for strong immunoreactivity, capable of effectively opsonising multiple strains of clinically-isolated GAS bacteria. Physicochemical assessment proved the alpha helix structure of the GAS B cell epitope was retained, impacting particle self-assembly and vaccine immunoreactivity. This study showed the capability for a self-adjuvanting cyclic delivery system to act as a vehicle for the delivery of GAS peptide antigens to treat GAS infection.