Lipid core peptide/poly(lactic-co-glycolic acid) as a highly potent intranasal vaccine delivery system against Group A streptococcus

Rheumatic heart disease represents a leading cause of mortality caused by Group A Streptococcus (GAS) infections transmitted through the respiratory route. Although GAS infections can be treated with antibiotics these are often inadequate. An efficacious GAS vaccine holds more promise, with intranasal vaccination especially attractive, as it mimics the natural route of infections and should be able to induce mucosal IgA and systemic IgG immunity. Nanoparticles were prepared by either encapsulating or coating lipopeptide-based vaccine candidate (LCP-1) on the surface of poly(lactic-co-glycolic acid) (PLGA). In vitro study showed that encapsulation of LCP-1 vaccine into nanoparticles improved uptake and maturations of antigen-presenting cells. The immunogenicity of lipopeptide incorporated PLGA-based nanoparticles was compared with peptides co-administered with mucosal adjuvant cholera toxin B in mice upon intranasal administration. Higher levels of J14-specific salivary mucosal IgA and systemic antibody IgG titres were observed for groups immunized with encapsulated LCP-1 compared to LCP-1 coated nanoparticles or free LCP-1. Systemic antibodies obtained from LCP-1 encapsulated PLGA NPs inhibited the growth of bacteria in six different GAS strains. Our results show that PLGA-based lipopeptide delivery is a promising approach for rational design of a simple, effective and patient friendly intranasal GAS vaccine resulting in mucosal IgA response

Ursodeoxycholic acid and lithocholic acid exert anti-inflammatory actions in the colon

Inflammatory bowel diseases (IBD) comprise a group of common and debilitating chronic intestinal disorders for which currently available therapies are often unsatisfactory. The naturally occurring secondary bile acid, ursodeoxycholic acid (UDCA), has well-established anti-inflammatory and cytoprotective actions and may therefore be effective in treating IBD. We aimed to investigate regulation of colonic inflammatory responses by UDCA and to determine the potential impact of bacterial metabolism on its therapeutic actions. The anti-inflammatory efficacy of UDCA, a nonmetabolizable analog, 6 alpha-methyl-UDCA (6-MUDCA), and its primary colonic metabolite lithocholic acid (LCA) was assessed in the murine dextran sodium sulfate (DSS) model of mucosal injury. The effects of bile acids on cytokine (TNF-alpha, IL-6, Il-1 beta, and IFN-alpha) release from cultured colonic epithelial cells and mouse colonic tissue in vivo were investigated. Luminal bile acids were measured by gas chromatography-mass spectrometry. UDCA attenuated release of proinflammatory cytokines from colonic epithelial cells in vitro and was protective against the development of colonic inflammation in vivo. In contrast, although 6-MUDCA mimicked the effects of UDCA on epithelial cytokine release in vitro, it was ineffective in preventing inflammation in the DSS model. In UDCA-treated mice, LCA became the most common colonic bile acid. Finally, LCA treatment more potently inhibited epithelial cytokine release and protected against DSS-induced mucosal inflammation than did UDCA. These studies identify a new role for the primary metabolite of UDCA, LCA, in preventing colonic inflammation and suggest that microbial metabolism of UDCA is necessary for the full expression of its protective actions.NEW & NOTEWORTHY On the basis of its cytoprotective and anti-inflammatory actions, the secondary bile acid ursodeoxycholic acid (UDCA) has well-established uses in both traditional and Western medicine. We identify a new role for the primary metabolite of UDCA, lithocholic acid, as a potent inhibitor of intestinal inflammatory responses, and we present data to suggest that microbial metab-olism of UDCA is necessary for the full expression of its protective effects against colonic inflammation

Liposome-based intranasal Delivery of lipopeptide vaccine candidates against Group A Streptococcus

Group A streptococcus (GAS), an exclusively human pathogen, causes a wide range of diseases ranging from trivial to life threatening. Treatment of infection is often ineffective following entry of bacteria into the bloodstream. To date, there is no vaccine available against GAS. In this study, cationic liposomes encapsulating lipopeptide-based vaccine candidates against GAS have been employed for intranasal vaccine delivery. Cationic liposomes were prepared with dimethyldioctadecylammonium bromide (DDAB) using the film hydration method. Female Swiss mice were immunized intranasally with the liposomes. In contrast to unmodified peptides, lipopeptides entrapped by liposomes induced both mucosal and systemic immunity, IgA and IgG (IgG1 and IgG2a) production in mice, respectively. High levels of antibody (IgA and IgG) titres were detected even five months post immunization. Thus, the combination of lipopeptides and liposomes generates a very promising delivery system for intranasal vaccines

Multilayer engineered nanoliposomes as a novel tool for oral delivery of lipopeptide-based vaccines against group A Streptococcus

Aim: To develop an oral nanovaccine delivery system for lipopeptide-based vaccine candidate against group A Streptococcus. Materials & methods: Lipid-core peptide-1-loaded nanoliposomes were prepared as a template and coated with opposite-charged polyelectrolytes to produce particles with siz

Group A Streptococcal vaccine candidate: contribution of epitope to size, antigen presenting cell interaction and immunogenicity

Aim: Utilize lipopeptide vaccine delivery system to develop a vaccine candidate against Group A Streptococcus. Materials & methods: Lipopeptides synthesized by solid-phase peptide synthesis-bearing carboxyl (C)-terminal and amino (N)-terminal Group A Streptococcus peptide epitopes. Nanoparticles formed were evaluated in vivo. Results: Immune responses were induced in mice without additional adjuvant. We demonstrated for the first time that incorporation of the C-terminal epitope significantly enhanced the N-terminal epitope-specific antibody response and correlated with forming smaller nanoparticles. Antigen-presenting cells had increased uptake and maturation by smaller, more immunogenic nanoparticles. Antibodies raised by vaccination recognized isolates. Conclusion: Demonstrated the lipopeptidic nanoparticles to induce an immune response which can be influenced by the combined effect of epitope choice and size

Double adjuvanting strategy for peptide-based vaccines: trimethyl chitosan nanoparticles for lipopeptide delivery

Aim: To develop novel polymer-based nanoscale delivery system for lipopeptide-based vaccine against group A Streptococcus (GAS). Materials & methods: Four types of lipopeptide antigen-loaded polymeric nanoparticles (NP) were prepared. NP were accessed for their capacity to be taken up by dendritic cells; effect on dendritic cell maturation; ability to induce mucosal and systemic immunity; and capability to induce antibody responses that opsonize GAS bacteria. Results & discussion: The combination of adjuvanting properties of lipopeptides and dextran/trimethyl chitosan-based NP had a synergistic effect on humoral immunity, and the produced antibodies showed high opsonic activity against clinical GAS isolates. Conclusion: Biocompatible NP-bearing trimethyl chitosan and dextran are efficient as mucosal adjuvants for the intranasal delivery of lipopeptide-based vaccines

Enhancing vaccine efficacy by engineering a complex synthetic peptide to become a super immunogen

Peptides offer enormous promise as vaccines to prevent and protect against many infectious and noninfectious diseases. However, to date, limited vaccine efficacy has been reported and none have been licensed for human use. Innovative ways to enhance their immunogenicity are being tested, but rational sequence modification as a means to improve immune responsiveness has been neglected. Our objective was to establish a two-step generic protocol to modify defined amino acids of a helical peptide epitope to create a superior immunogen. Peptide variants of p145, a conserved helical peptide epitope from the M protein of Streptococcus pyogenes, were designed by exchanging one amino acid at a time, without altering their alpha-helical structure, which is required for correct antigenicity. The immunogenicities of new peptides were assessed in outbred mice. Vaccine efficacy was assessed in a skin challenge and invasive disease model. Out of 86 variants of p145, seven amino acid substitutions were selected and made the basis of the design for 18 new peptides. Of these, 13 were more immunogenic than p145; 7 induced Abs with significantly higher affinity for p145 than Abs induced by p145 itself; and 1 peptide induced more than 10,000-fold greater protection following challenge than the parent peptide. This peptide also only required a single immunization (compared with three immunizations with the parent peptide) to induce complete protection against invasive streptococcal disease. This study defines a strategy to rationally improve the immunogenicity of peptides and will have broad applicability to the development of vaccines for infectious and noninfectious diseases