Vasoactive Intestinal Peptide Amphiphile Micelle Chemical Structure and Hydrophobic Domain Influence Immunomodulatory Potentiation

Polymer Micelles as Nanocarriers of Bioactive Peptides

Bioactive peptides (BPs) have demonstrated diverse inhibitory effects against parasites, viruses, bacteria, fungi, and other pathogens, and therefore, they have been extensively used for developing various therapeutics. However, several challenges for the clinical use of BPs related to their stability, bioavailability, and cytotoxicity remain. The encapsulation of BPs in polymer micelles (PMs) has emerged as an effective strategy that can improve the pharmacological profiles, safety, and efficacy of treatments. This review describes the recent advances of micellar carriers of peptides with antimicrobial, anticancer, anti-inflammatory, immunomodulatory, and anti-diabetic activities. The mode of action of BPs and the unique characteristics of PMs are described, and a critical evaluation of their advantages and disadvantages is made. The upcoming challenges and future perspectives of micellar systems carrying BPs are discussed as well.

Adjuvant Templating Improves On-Target/Off-Target Antibody Ratio Better than Linker Addition for M2-Derived Peptide Amphiphile Micelle Vaccines

BACKGROUND

Peptide amphiphile micelles (PAMs) are a promising lipid-based nanotechnology currently in development for a variety of applications ranging from atherosclerosis to cancer therapy. Especially relevant for immune applications, PAMs improve trafficking through lymphatic vessels, enhance uptake by antigen-presenting cells, and inhibit the protease-mediated degradation of cargo. However, the creation of the peptide amphiphiles (PAs) necessary to induce micellization often requires modifying an immunotarget peptide with non-native moieties, which can induce the production of off-target antibodies.

METHODS

PAs containing different linkers between the antigen and non-native flanking regions were synthesized and physically characterized. BALB/c mice were then subcutaneously immunized on days 0 and 14 with these formulations and ELISAs were conducted on the sera collected from vaccinated mice on day 35 to evaluate antibody responses.

RESULTS

We determined that Palm2K-M22-16-(KE)4 PAMs elicited off-target antibody responses and sought to avoid these unintended responses by adding linkers in between the M22-16 antigen and the non-native flanking regions (i.e., Palm2K- and -(KE)4) of the PA. Most significantly, the addition of diproline linkers on either side of the M22-16 antigen conferred a loss of β-sheet structure, whereas changing the method of lipid attachment from Palm2K- to Pam2CS-induced the formation of primarily spherical micelles compared to a mixture of spherical and short cylindrical micelles. Despite these morphological changes, all linker-containing PAMs still induced the production of off-target antibodies. Excitingly, however, the formulation containing a Pam2CS moiety (intended to mimic the adjuvanticity of the TLR2 agonist adjuvant Pam2CSK4) elicited high on-target antibody titers similar to those induced by PAMs co-delivered with Pam2CSK4.

CONCLUSIONS

While the linkers tested did not completely eliminate the production of off-target antibodies elicited by the PAMs, the inclusion of a Pam2CS moiety both increased the amount of on-target antibodies and improved the ratio of on-target to off-target antibodies in response to the M22-16 vaccine.

Peptide Antigen Modifications Influence the On-Target and Off-Target Antibody Response for an Influenza Subunit Vaccine

BACKGROUND/OBJECTIVES

Peptide amphiphile micelles (PAMs) are an exciting nanotechnology currently being studied for a variety of biomedical applications, especially for drug delivery. Specifically, PAMs can enhance in vivo trafficking, cell-targeting, and cell interactions/internalization. However, modifying peptides, as is commonly performed to induce micellization, can influence their bioactivity. In our previous work, murine antibody responses to PAMs containing the influenza antigen M22-16 were slightly incongruous with prior PAM vaccine studies using other antigens. In this current work, the effect of native protein linkages and non-native micellizing moieties on M2 immunogenicity was studied.

METHODS

PAMs were synthesized using an elongated M2 antigen (i.e., Palm2K-M21-24-(KE)4). The PAMs were characterized, then their immunogenicity was evaluated with bone marrow-derived dendritic cells and in mice.

RESULTS

Although the modification scheme yielded immunogenic PAMs, these PAMs induced a substantial amount of off-target antibody production compared to unmodified peptidyl micelles (PMs, M21-24 peptide).

CONCLUSIONS

While the impact PAM-induced off-target antibodies had on vaccine efficacy remains to be elucidated, on-target antibodies from both PAM- and PM-vaccinated mice were excitingly able to recognize the M2 antigen within the context of the full M2 protein. This provides preliminary evidence that the PAM-induced on-target antibodies will at minimum be able to recognize the influenza virus upon exposure.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 μg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.