Der Zen Liu

Mucoadhesive liposomes for intranasal immunization with an avian influenza virus vaccine in chickens

The aim of this study was to characterize a nasally delivered bioadhesive liposome using an inactivated H5N3 virus as a model antigen. Bioadhesive liposomes were developed using tremella (T) or xanthan gum (XG) as the bioadhesive polysaccharide. Using chickens as the target animal, we evaluated whether delivery of a bioadhesive liposomal influenza vaccine via a mucosal site of infection could improve vaccine effectiveness. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cytotoxicity assays demonstrated that T, XG and liposomes were non toxic to chicken spleen macrophages. Enzyme-linked immunosorbent assay (ELISA) was used to determine the adjuvant effect of the bioadhesive liposomal-vaccines. Chickens immunized with a low dose (200 microL) of bioadhesive liposomal influenza vaccine had significantly higher mucosal and serum antibody levels (P<0.05). In addition, liposomes mixed with a low-viscosity bioadhesive gel used for nasal delivery resulted in superior antibody responses compared with liposomes mixed with a high-viscosity gel (P<0.05). This suggest that a low-viscosity gel mixed with liposomes is more suitable for nasal delivery, and that chickens elicit higher mucosal secretory immunoglobulin A (s-IgA) and serum IgG after two vaccinations.

Diosgenin, a Plant-Derived Sapogenin, Enhances Regulatory T-Cell Immunity in the Intestine of Mice with Food Allergy

It was hypothesized that the suppressive effect of diosgenin (1) on the intestinal T helper (Th)2 responses is associated with an enhancement of the regulatory T-cell immunity. Ovalbumin (OVA)-sensitized BALB/c mice were gavaged daily with 1 and received repeatedly oral OVA challenges to induce intestinal allergic responses. The expression of Th2- and Treg-related cytokines and transcription factors was examined by immunohistochemical staining and RT-PCR. Administration of 1 markedly attenuated the intestinal expression of interleukin (IL)-4 and GATA3. In addition, administration of 1 reversed the diminished density of intestinal Foxp3(+) cells induced by OVA oral challenges and enhanced the expression of IL-10 by Foxp3(+) cells markedly. These results suggest that the suppressive effect of 1 on allergen-induced intestinal Th2 responses is closely associated with an up-regulation of the regulatory T-cell immunity in the inflammatory site.

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets.

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5 ± 0.5% of uncoated ones to 17.9 ± 0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9–12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g. ≤ 24 h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.

Effect of lipopolysaccharide on intranasal administration of liposomal Newcastle disease virus vaccine to SPF chickens

In order to potentiate the low immunogenicity of the inactivated Newcastle disease virus immunized into chickens by mucosal route, liposomes as a drug delivery system and LPS (lipopolysaccharide) as an immuno-stimulator were evaluated. Here, we report a new nasal delivery system of inactivated Newcastle disease virus (NDV) vaccine. The intranasal vaccine was based on different lipids to form MLV (multi-lamellar vehicles) liposomes. The liposomes had combined carrier and adjuvant activities, which induced strong systemic (serum) and local (lung and nasal) humoral responses in SPF (specific-pathogen-free) chickens, and provided protective immunity. PC-Lip (phosphatidylcholine-liposome) elicited significant mucosal secretary immunoglobulin A (s-IgA) levels (p<0.05) in tracheal lavage fluid and serum IgG levels (p<0.05). In response to virulent viral challenge, birds treated with PBS (phosphate buffered saline) as control group died, whereas 80% of chickens which received PC-Lip, PC-Lip-LPS, PS-Lip (phosphatidylserine-liposome), and PS-Lip-LPS survived. HAI titers were 1:2560 in the PS-Lip-LPS group and 1:1280 in the PC-Lip, PC-Lip-LPS, and PS-Lip groups after two vaccinations. The results suggest that PC-Lip or PS-Lip might thus be suitable as a potential adjuvant for mucosal vaccination against NDV in chickens.

The influence of liposomal adjuvant on intranasal vaccination of chickens against Newcastle disease.

The adjuvant effect of liposomes formulated with three phospholipids including phosphatidylcholine-liposomes (PC-Lip), phosphatidylserine-liposomes (PS-Lip), and stearylamine-liposomes (SA-Lip) was compared with virus alone using inactivated Newcastle disease virus (NDV) as a model antigen. The difference in adjuvanticity was evaluated using the haemagglutination-inhibition (HI) test, enzyme-linked immunosorbent assay, and a challenge study following intranasal inoculation of specific pathogen-free chickens. After two inoculations, a liposomal vaccine consisting of NDV in PC-Lip resulted in a significant increase in HI titre, up to 32-fold higher than a vaccine containing virus alone and 320-fold higher than a vaccine containing NDV in SA-Lip. PC-Lip also elicited a significant mucosal secretary immunoglobulin A response (P<0.05) in tracheal lavages and a serum IgG response (P<0.05). In response to viral challenge, all control animals died, whereas 90% of animals which received PC-Lip survived. The results suggest that PC-Lip may be suitable as an adjuvant for mucosal vaccination against NDV in chickens.

Evaluation of encapsulated Newcastle disease virus liposomes using various phospholipids administered to improve chicken humoral immunity

We propose the adjuvant effects of phospholipid liposome compositions using intranasal inoculation of a liposomal-Newcastle disease virus (NDV) vaccine in chickens. The immunogenicity of three liposome formulations was determined in chickens using the hemagglutination-inhibition (HI) test, nasal secretory immunoglobulin A and serum immunoglobulin A (IgG) antibody titers using the enzyme-linked immunosorbent assay. The immune response against NDV antigens was determined after immunization with neutral charged liposomes composed of egg phosphatidylcholine (EPC) (60 micromol), cholesterol (Chol) (15 micromol), and EPC-liposomes (EPC-Lip), which elicited strong systemic (serum) and local (nasal) humoral responses. However, the intranasal administration with cationic charged liposomes composed of EPC (30 micromol), stearylamine (SA) (15 micromol), Chol (15 micromol), and SA-liposomes (SA-Lip) induced poor humoral immune responses. Only the vaccine formulated with anionic charged liposomes composed of EPC (30 micromol), dipalmitoylphosphatidylserine (15 micromol), Chol (15 micromol), and phosphatidylserine-liposomes (PS-Lip) elicited the highest titers of HI antibodies. These are the first results to suggest that antigen delivery using EPC-Lip is very useful in enhancing antibody production at the mucosal site and in serum.

Effects of tremella–alginate–liposome encapsulation on oral delivery of inactivated H5N3 vaccine

In this study, we evaluated a system for oral vaccine delivery, consisting of liposomes coated first with a layer of tremella and then with an outer layer of acid-induced alginate. In vitro release studies showed that the triple layer of alginate–tremella–liposomes was more resistant to an acidic pH and modulated the release profiles at an alkaline pH. Transepithelial electrical resistance (TEER) studies revealed that liposomes or tremella-coated liposomes were able to open tight junctions of the Caco-2 cell monolayer. In mice, although serum immunoglobulin G (IgG) was not expected to increase and haemagglutination inhibition showed that antibody levels were still too low to provide sufficient protection, alginate–tremella–liposomes encapsulated virus-induced intestinal secretory immunoglobulin A (s-IgA) production to provide protection against virus infection. In conclusion, an oral virus vaccine entrapped in alginate–tremella–liposomes improved the mucosal antiviral s-IgA response. This system may have potential use as a carrier for oral vaccine delivery.

Cannabidiol induced a contrasting pro-apoptotic effect between freshly isolated and precultured human monocytes

It has been documented that cannabidiol (CBD) induced apoptosis in a variety of transformed cells, including lymphocytic and monocytic leukemias. In contrast, a differential sensitivity between normal lymphocytes and monocytes to CBD-mediated apoptosis has been reported. The present study investigated the pro-apoptotic effect of CBD on human peripheral monocytes that were either freshly isolated or precultured for 72h. CBD markedly enhanced apoptosis of freshly isolated monocytes in a time- and concentration-dependent manner, whereas precultured monocytes were insensitive. By comparison, both cells were sensitive to doxorubicin-induced apoptosis. CBD significantly diminished the cellular thiols and glutathione in freshly isolated monocytes. The apoptosis induced by CBD was abrogated in the presence of N-acetyl-L-cysteine, a precursor of glutathione. In addition, precultured monocytes contained a significantly greater level of glutathione and heme oxygenase-1 (HO-1) compared to the freshly isolated cells. The HO-1 competitive inhibitor zinc protoporphyrin partially but significantly restored the sensitivity of precultured monocytes to CBD-mediated apoptosis. Collectively, our results demonstrated a contrasting pro-apoptotic effect of CBD between precultured and freshly isolated monocytes, which was closely associated with the cellular level of glutathione and the antioxidative capability of the cells.

Cannabidiol attenuates delayed-type hypersensitivity reactions via suppressing T-cell and macrophage reactivity

Aim:To investigate the effects cannabidiol (CBD) on delayed-type hypersensitivity (DTH) reactions and antigen-induced T-cell cytokine expression.Methods:DTH was induced by subcutaneous ovalbumin (OVA) challenge to the footpads of mice sensitized with OVA. Inflammatory reactions were measured by footpad swelling and histological analysis. Antigen-induced cytokine expression by OVA-primed splenocytes was measured using ELISA and RT-PCR.Results:CBD (1-10 mg/kg) administration, in a dose-dependent fashion, significantly attenuated inflammatory reactions associated with DTH in the footpads of mice sensitized and challenged with OVA. Histological examination revealed that CBD suppressed the infiltration of T cells and macrophages, and the expression of interferon (IFN)-γ and tumor necrosis factor-α, two pro-inflammatory cytokines implicated in DTH in the inflammatory site. In contrast, the expression of interleukin (IL)-10 in the footpads was enhanced by CBD administration. In addition, CBD at concentrations devoid of cytotoxic effects (1-4 μmol/L) attenuated OVA-induced IFN-γ production by OVA-primed splenocytes, whereas IL-4 was unaffected.Conclusion:CBD curbs DTH reactions via suppressing the infiltration and functional activity of T cells and macrophages in the inflammatory site, suggesting a therapeutic potential for CBD for the treatment of type IV hypersensitivity.

Adjuvant effect of liposome in chicken result from induction of nitric oxide

Intranasal delivery of liposome-encapsulated inactivated Newcastle Disease virus (NDV) is known to be an effective vaccine for inducing immunity in the respiratory tract from our previous reports. Four-week-old specific pathogen-free chickens were intranasally immunized with NDV entrapped in phosphatidylcholine-liposomes (PC-Lip). The mucosal levels of anti-NDV s-immunoglobulin A (IgA), serum IgG, a high hemagglutination inhibition titer (1:640), and the high survival rate with the PC-Lip vaccine were comparable to those of our previous report. The immune mechanisms of the PC-Lip adjuvant were determined by in vitro cellular experiments using the NO production of chicken spleen macrophages. The most important finding of this study was proving that macrophages were stimulated by PC-Lip via the extracellular regulated kinase (ERK) 1/2 and nuclear factor (NF)-κB activation pathways. This finding may be useful for developing potent mucosal vaccine delivery systems in the future.