Surface assembly of poly(I:C) on polyethyleneimine-modified gelatin nanoparticles as immunostimulatory carriers for mucosal antigen delivery.

The mucosal immune system is the host's first line of defense against invasion by foreign pathogens. Gelatin nanoparticles (GNPs) are suitable carriers for the delivery of antigens via various routes of administration. In the present study, GNPs were modified with polyethyleneimine (PEI), a positively charged polymer. Then, ovalbumin (OVA) and polyinosinic:polycytidylic acid (poly(I:C)), an immunostimulant, were adsorbed onto the surface of the positively charged GNPs. We assessed whether GNPs could act as an effective mucosal vaccine that is capable of inducing both mucosal and systemic immune responses. The results showed that GNPs effectively adsorbed OVA/poly(I:C), facilitated cellular uptake by RAW 264.7 macrophage cells and murine bone marrow-derived dendritic cells (BMDCs) in vitro, and led to increased expression of the maturation markers CD80 and CD86 on BMDCs. Furthermore, GNPs induced increased secretion of proinflammatory cytokines in both RAW 264.7 and BMDCs. C57BL/6 mice that were intranasally twice-immunized with OVA/poly(I:C)-loaded GNPs produced high levels of serum OVA-specific IgG antibodies and secretory IgA in nasal and lung lavage. Spleen cells from immunized mice were collected and re-stimulated with OVA, and results showed significantly augmented production of IFN-γ, IL-4, IL-5, and IL-6 in mice that received OVA/poly(I:C)-loaded GNPs. Moreover, intranasal immunization with OVA/poly(I:C)-loaded GNPs resulted in the inhibition of EG7 tumor growth in C57BL/6 mice. Taken together, these results indicate that nasal administration of OVA/poly(I:C)-loaded GNPs elicited effective mucosal and systemic immune responses, which might be useful for further applications of antigen delivery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1228-1237, 2019.

Galactosylated liposome as a dendritic cell-targeted mucosal vaccine for inducing protective anti-tumor immunity.

Mucosal surfaces contain specialized dendritic cells (DCs) that are able to recognize foreign pathogens and mount protective immunity. We previously demonstrated that intranasal administration of targeted galactosylated liposomes can elicit mucosal and systemic antibody responses. In the present study, we assessed whether galactosylated liposomes could act as an effective DC-targeted mucosal vaccine that would be capable of inducing systemic anti-tumor immunity as well as antibody responses. We show that targeted galactosylated liposomes effectively facilitated antigen uptake by DCs beyond that mediated by unmodified liposomes both in vitro and in vivo. Targeted galactosylated liposomes induced higher levels of pro-inflammatory cytokines than unmodified liposomes in vitro. C57BL/6 mice thrice immunized intranasally with ovalbumin (OVA)-encapsulated galactosylated liposomes produced high levels of OVA-specific IgG antibodies in their serum. Spleen cells from mice receiving galactosylated liposomes were restimulated with OVA and showed significantly augmented levels of IFN-γ, IL-4, IL-5 and IL-6. In addition, intranasal administration of OVA-encapsulated beta-galactosylated liposomes resulted in complete protection against EG7 tumor challenge in C57BL/6 mice. Taken together, these results indicate that nasal administration of a galactosylated liposome vaccine mediates the development of an effective immunity against tumors and might be useful for further clinical anti-tumoral applications.

Dried fruit of the Luffa sponge as a source of chitin for applications as skin substitutes.

LUFFACHITIN obtained from the residue of the sponge-like dried fruit of Luffa aegyptiaca was developed as a weavable skin substitute in this study. A chemical analysis revealed that LUFFACHITIN was composed of a copolymer containing N-acetyl-glucosamine (~40%) as a major monomer with a filamentary structure as demonstrated by both optical and scanning electron microscopy. The pulp-like white residue of the sponge-like dried fruit of Luffa aegyptiaca after treatment was then woven into a thin, porous membrane by filtration and lyophilization as a skin substitute for conducting wound-healing study on rats. The results indicated that the LUFFACHITIN membrane showed significant wound-healing enhancement (25 days to complete healing) compared to cotton gauze (>30 days), but not inferior to that of SACCHACHITIN. Furthermore, the LUFFACHITIN membrane had advantages of having a high yield, better physical properties for fabrication, and a more attractive appearance.

Application of galactose-modified liposomes as a potent antigen presenting cell targeted carrier for intranasal immunization.

The mucosal immune system produces secretory IgA (sIgA) as the first line of defense against invasion by foreign pathogens. Our aim was to develop a galactose-modified liposome as a targeted carrier which can be specifically recognized by macrophage, one of the most important antigen presenting cells. First, galactose was covalently conjugated with 1,2-didodecanoyl-sn-glycero-3-phosphoethanolamine (DLPE) to give a targeted ligand, a galactosyl lipid. The galactosyl lipid was then incorporated into a liposomal bilayer to form a galactosylated liposome carrier. Further, the ovalbumin (OVA) was encapsulated into the galactosylated liposome carriers and mice were intranasally immunized. Confocal laser scanning microscopy and flow cytometry analysis showed that the targeted galactosylated liposome carrier had a higher uptake rate than unmodified liposomes. The targeted galactosylated liposome induced higher levels of tumor necrosis factor-α and interleukin-6 production than unmodified liposomes (P<0.05). Furthermore, 6-week-old BALB/c female mice immunized with the OVA-encapsulated targeted galactosylated liposome had significantly higher OVA-specific s-IgA levels in the nasal and lung wash fluid (P<0.05). In addition, the targeted galactosylated liposome simultaneously augmented the serum IgG antibody response. In summary, the OVA-encapsulated targeted galactosylated liposome induced significantly higher mucosal IgA and systemic IgG antibody titers and is a potential antigen delivery carrier for further clinical applications.