Cationic Nanoparticle-Stabilized Vaccine Delivery System for the H9N2 Vaccine to Promote Immune Response in Chickens.

Chinese yam polysaccharides (CYPs) have received wide attention for their immunomodulatory activity. Our previous studies had discovered that the Chinese yam polysaccharide PLGA-stabilized Pickering emulsion (CYP-PPAS) can serve as an efficient adjuvant to trigger powerful humoral and cellular immunity. Recently, positively charged nano-adjuvants are easily taken up by antigen-presenting cells, potentially resulting in lysosomal escape, the promotion of antigen cross-presentation, and the induction of CD8 T-cell response. However, reports on the practical application of cationic Pickering emulsions as adjuvants are very limited. Considering the economic damage and public-health risks caused by the H9N2 influenza virus, it is urgent to develop an effective adjuvant for boosting humoral and cellular immunity against influenza virus infection. Here, we applied polyethyleneimine-modified Chinese yam polysaccharide PLGA nanoparticles as particle stabilizers and squalene as the oil core to fabricate a positively charged nanoparticle-stabilized Pickering emulsion adjuvant system (PEI-CYP-PPAS). The cationic Pickering emulsion of PEI-CYP-PPAS was utilized as an adjuvant for the H9N2 Avian influenza vaccine, and the adjuvant activity was compared with the Pickering emulsion of CYP-PPAS and the commercial adjuvant (aluminum adjuvant). The PEI-CYP-PPAS, with a size of about 1164.66 nm and a ζ potential of 33.23 mV, could increase the H9N2 antigen loading efficiency by 83.99%. After vaccination with Pickering emulsions based on H9N2 vaccines, PEI-CYP-PPAS generated higher HI titers and stronger IgG antibodies than CYP-PPAS and Alum and increased the immune organ index of the spleen and bursa of Fabricius without immune organ injury. Moreover, treatment with PEI-CYP-PPAS/H9N2 induced CD4+ and CD8+ T-cell activation, a high lymphocyte proliferation index, and increased cytokine expression of IL-4, IL-6, and IFN-γ. Thus, compared with the CYP-PPAS and aluminum adjuvant, the cationic nanoparticle-stabilized vaccine delivery system of PEI-CYP-PPAS was an effective adjuvant for H9N2 vaccination to elicit powerful humoral and cellular immune responses.

Effects of Chinese yam polysaccharides on the immune function and serum biochemical indexes of broilers.

The purpose of this experiment was to investigate the effects of Chinese yam polysaccharides (CYP) in diets on the immune function of broilers. A total of 360 (1-day-old, sex balance) healthy growing broilers with similar body weight (39.54 ± 0.51 g) were randomly divided into control (0.00 g/kg), CYP I (0.25 g/kg), CYP II (0.50 g/kg), and CYP III (1.00 g/kg) groups. Each group contains 3 replicates with 30 broilers in each replicate, and the feeding trial lasted 48 d. The results showed that compared with the control group, the CYP II group had higher thymus index, serum IgA, complement C3, C4, IGF-I, T3, T4, INS, GH, IL-2, IL-4, IL-6, and TNF-α levels (P < 0.05) at 28, 48 d, respectively. In addition, the spleen index, serum IgM and IgG concentrations in CYP II group were higher than those in the control group at 28 d (P < 0.05). Results indicated that 0.50 g/kg CYP supplementation improved the immune function of broilers, and the CYP has a potential biological function as a green additive in broilers.

Chinese yam polysaccharides PLGA-stabilized Pickering emulsion as an adjuvant system for PCV- 2 vaccine to enhance immune response.

Chinese yam polysaccharides (CYP) exhibit superior adjuvant activity and modulate the immune response, but the low bioavailability limits their clinical application. Pickering emulsions have been proven as an efficient vaccine delivery system to enhance the immune response. Here, we used the Chinese yam polysaccharides PLGA-stabilized Pickering emulsion adjuvant system (CYP-PPAS) loaded with Porcine circovirus 2 as a vaccine and focused on investigating its adjuvant activity on humoral and cellular immunity in mice. The CYP-PPAS increased PCV-2 antigen loading efficiency and showed a high antigen uptake efficiency by macrophages in vitro. In vivo, CYP-PPAS significantly facilitated DCs maturation in draining lymph nodes than CYP or PPAS alone group. The CYP-PPAS also induced an increased proliferation index and a CD4+/CD8+ ratio. Meanwhile, in contrast to the CYP and PPAS groups, CYP-PPAS elicited a stronger anti-PCV-2 IgG and mixed Th1/Th2 immune response. Specifically, the CYP-PPAS group displayed the high expression of CD107a, FasL, and Granzyme B secretion to augment a strong cytotoxic lymphocyte response. Overall, the CYP-PPAS was a successful adjuvant system for promoting humoral and cellular immune responses, which opens up an avenue for the development of effective adjuvants against infectious diseases.

Pickering emulsion stabilized by Chinese Yam polysaccharides PLGA for enhanced humoral and cellular immune responses.

As an important ingredient of Chinese yam, Chinese yam polysaccharides have received wide attention for their remarkable adjuvant activity. Pickering emulsion is an attractive platform for the delivery of vaccines. Our previous study has demonstrated that the Chinese yam polysaccharides PLGA-stabilized Pickering emulsion (CYP-PPAS) is a potentially safe and efficient adjuvant to improve the immune response. In this work, we further investigate the adjuvant activity of CYP-PPAS on cellular immunity. In vitro, the CYP-PPAS increased antigen uptake efficiency by DCs. In vivo, CYP-PPAS triggered the recruitment of DCs and macrophages and subsequently facilitated DCs maturation and antigen migration to lymph nodes. Furthermore, CYP-PPAS induced a robust humoral response and Th1/Th2 immune response, enhanced the activation of CD4+ and CD8+ T lymphocyte subpopulations, and also promoted the activation of cytotoxic T lymphocyte response. As a result, the CYP-PPAS serves as a promising vaccine delivery system to induce robust humoral and cellular immunities against diseases.

Fabrication and characterization of Chinese yam polysaccharides PLGA nanoparticles stabilized Pickering emulsion as an efficient adjuvant.

The Chinese yam polysaccharides PLGA nanoparticles were applied as stabilizers in this study to prepare O/W Pickering emulsion. The optimized preparation conditions were PLGA concentration of 5 mg/mL, ultrasonic power of 50 %, and ultrasonic time of 2 min. The CYP-PPAS emulsion exhibits a raspberry-like morphology with a large number of nanoparticles surrounding the oil droplets. The CYP-PPAS emulsion exhibited outstanding stability at 4 °C and 37 °C for 28 days with high antigen loading efficiency and provided a controlled and sustained release of Chinese yam polysaccharides and OVA antigen in vitro. CYP-PPAS/OVA elicited robust antigen-specific immune response and induced a mixed Th1/Th2 immune response after immunization. Furthermore, CYP-PPAS/OVA caused a high CD4+/CD8+ ratio leading in increased activation of splenic T lymphocytes subpopulations. Moreover, CYP-PPAS is a safe vaccination adjuvant with high safety profile in vivo. Thus, the novel designed Pickering emulsion CYP-PPAS was a safe and effective adjuvant for inducing the strong and long-term immune response.

Effect of in vitro simulated gastrointestinal digestion on the antioxidant activity, molecular weight, and microstructure of polysaccharides from Chinese yam.

In this study, we investigated the antioxidant properties and the changes of molecular weight (Mw), antioxidant activity, and microstructure of Chinese yam polysaccharides (CYP-A) during in vitro digestion. Results showed that the scavenging rate of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical of CYP-A was approximately 79% at the concentration of 6 mg/mL. Furthermore, the antioxidant ability positively correlated with the concentration of CYP-A. In addition, the Mw of CYP-A decreased (p < 0.05) after intestinal digestion. Fourier transform infrared showed that the degrees of esterification of CYP-A increased to 39.04% after 6 h of gastric digestion. Moreover, the structure of CYP-A changed after in vitro gastric digestion. The scanning electron microscope (SEM) images indicated that the surface morphology of CYP-A turned from smooth and irregular to a layered honeycomb after gastrointestinal digestion in vitro. Surprisingly, the activity of DPPH radical scavenging significantly increased (p < 0.05) in the intestinal digested samples of CYP-A, which showed a positive correlation with the concentration of CYP-A. However, the reducing power significantly decreased (p < 0.05) after in vitro intestinal digestion.

Effects of Chinese yam Polysaccharides on the Muscle Tissues Development-Related Genes Expression in Breast and Thigh Muscle of Broilers.

This experiment was conducted to evaluate the effects of dietary Chinese yam polysaccharides (CYP) on myogenic differentiation 1 (MYOD1), myogenin (MYOG), and myostatin (MSTN) mRNA expression of breast and thigh muscle tissues in broilers. A total of 360 (1-day-old, gender-balanced) crossbred broilers chicks with similar body weight (BW) were randomly distributed into four groups, with three replicates in each group and each replicate included 30 broilers. The feeding trial lasted for 48 days. Experimental broilers were fed 0.00 mg/kg basal diet (control group), 250 mg/kg, 500 mg/kg, and 1000 mg/kg CYP, respectively. The results showed that CYP250 and CYP500 groups had higher thigh muscle percentage (TMP) compared to the control group (p < 0.05). Meanwhile, the expression of MYOD1, MYOG mRNA in breast muscle tissues of CYP500 and CYP1000 groups was higher (p < 0.05), and the expression of MSTN mRNA in thigh muscle of CYP250, CYP500, and CYP1000 groups was lower than that of the control group (p < 0.05). In addition, there was no significant difference in the expression of MYOD1 mRNA in the thigh muscle tissue of each group (p > 0.05). Bivariate correlation analysis showed that the expression levels of MYOD1, MYOG, and MSTN mRNA in the thigh muscle tissue of broiler chickens in the CYP500 group were positively correlated with TMP. However, the expression of MYOG mRNA in thigh muscle tissue of the CYP1000 group was negatively correlated with TMP. In general, this study indicated that appropriate dietary CYP supplementation influenced the growth and development of thigh muscle tissue in broilers by altering TMP and muscle tissue development-related genes expression. Therefore, CYP could be used as a potential feed additive to promote the development of muscle tissues in broilers.