Oral pre-administration of Purslane polysaccharides enhance immune responses to inactivated foot-and-mouth disease vaccine in mice

Preparation Optimization and Immunological Activity Studies of Portulaca oleracea L. Polysaccharides Liposomes

AIMS

This study combines traditional Chinese medicine polysaccharides with nanomaterials to enhance drug bioavailability and immunological activity.

BACKGROUND

The study of polysaccharide preparation, structure identification, pharmacological activity, and mechanism of action is deepening, but the research combined with the new drug delivery system is relatively weak, so the application of polysaccharides is still facing great limitations. In order to prolong the action time of polysaccharides and improve their bioavailability, liposome has become the most promising delivery carrier.

OBJECTIVES

The purpose of this study was to optimize the preparation process of Portulaca oleracea L. polysaccharides liposomes (POL-PL) and evaluate the immunoactivity in vitro.

METHODS

POL-PL was prepared by reverse evaporation, and the preparation process was optimized using the response surface methodology. The characteristic analysis of POL-PL was detected by the indicators including morphology, particle size, zeta potential, encapsulation efficiency, release, and stability. The effects of POL-PL on the proliferation and immunological activity of mouse spleen lymphocytes and RAW264.7 cells were evaluated in vitro.

RESULTS

POL-PL is highly homogeneous in morphology and particle size, and its sustained release improves the bioavailability of Portulaca oleracea L. polysaccharides (POL-P). Moreover, POL-PL treatment significantly enhanced the proliferation and phagocytic activity of RAW264.7 cells and increased the secretion of IL-6, TNF-α, IL-1β, and NO.

CONCLUSION

This study suggested that POL-PL were prepared successfully by reverse evaporation method, and POL-PL had immunoenhancing activity in vitro. The results provided a theoretical basis for further application of POL-PL.

The combination of vaccines and adjuvants to prevent the occurrence of high incidence of infectious diseases in bovine

As the global population grows, the demand for beef and dairy products is also increasing. The cattle industry is facing tremendous pressures and challenges. The expanding cattle industry has led to an increased risk of disease in cattle. These diseases not only cause economic losses but also pose threats to public health and safety. Hence, ensuring the health of cattle is crucial. Vaccination is one of the most economical and effective methods of preventing bovine infectious diseases. However, there are fewer comprehensive reviews of bovine vaccines available. In addition, the variable nature of bovine infectious diseases will result in weakened or even ineffective immune protection from existing vaccines. This shows that it is crucial to improve overall awareness of bovine vaccines. Adjuvants, which are crucial constituents of vaccines, have a significant role in enhancing vaccine response. This review aims to present the latest advances in bovine vaccines mainly including types of bovine vaccines, current status of development of commonly used vaccines, and vaccine adjuvants. In addition, this review highlights the main challenges and outstanding problems of bovine vaccines and adjuvants in the field of research and applications. This review provides a theoretical and practical basis for the eradication of global bovine infectious diseases.

Portulaca oleracea shows no ameliorative potential on ovariectomy-induced hormonal and estrous cycle dysregulation in normal cyclic rats: An experimental study

Background

Portulaca oleracea (PO) is a widely known plant utilized for its medicinal attributes in the treatment of different illnesses.

Objective

To investigate the effect of methanolic extract of PO (MEPO) on ovariectomy-induced reproductive toxicity in normal cyclic rats.

Materials and Methods

Twenty 10-wk-old normal cyclic rats weighing 110-200 g were randomly divided into four groups (n = 5/group). Group A served as the control and received distilled water only. Group B was ovariectomized without treatment, while groups C and D were ovariectomized but treated with 400 and 800 mg/kg of MEPO, respectively, for 14 days. At the end of the experiment, body weight, serum hormonal levels, and estrous cycles were monitored across the groups.

Results

Groups B, C, and D showed estrous cycle dysregulation and specific phase arrest when compared with the control. While a significant decrease in estradiol (p ≤ 0.001) and testosterone levels (p ≤ 0.001) were observed in groups B, C, and D, only groups C and D showed a significant increase in progesterone level when compared with the control (p ≤ 0.001, p = 0.01, respectively).

Conclusion

The administration of 400 and 800 mg/kg MEPO is ineffective in ameliorating estrous cycle disruption and hormonal changes seen in ovariectomized normal cyclic adult Wistar rats.

Antioxidant activity of purslane extract and its inhibitory effect on the lipid and protein oxidation of rabbit meat patties during chilled storage

BACKGROUND

Currently, synthetic antioxidants have been widely used to retard lipid and protein oxidation in the meat industry. However, consumers have concerns about these synthetic antioxidants because of their potential toxicological effects. Accordingly, natural antioxidants can be used as a result of their health safety compared to synthetic antioxidants. The present research aimed to assess the protective effects of purslane (Portulaca oleracea L.) extract (PE) against lipid and protein oxidation under chilled storage for 12 days. Rabbit meat patties were divided into five experimental groups: control (without extract), butylated hydroxytoluene BHT (with 0.02% BHT, w/w) and the different concentrations of PE (0.1%, 0.3% and 0.5%, w/w) added to rabbit meat patty labeled as 0.1% PE, 0.3% PE and 0.5% PE groups, respectively. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, lipid oxidation and protein oxidation were determined, and kinetic models were employed.

RESULTS

PE showed the strongest DPPH and ABTS radical scavenging activity, and the half maximal inhibitory concentrations (i.e. IC₅₀ ) of DPPH and ABTS radicals were 5.112 ± 0.384 and 12.607 ± 2.130 μg mL^-1 , respectively. Samples that were treated with PE showed low lipid and protein oxidation. Furthermore, the results of kinetic models indicated that PE could reduce the rates of lipid and protein oxidation.

CONCLUSION

PE showed a preservative effect with respect exerting a protective effect against lipid and protein oxidation under chilled storage conditions. Our findings demonstrate the strong potential of PE as a natural antioxidant in meat and meat products. © 2020 Society of Chemical Industry.

Carbohydrate-based adjuvants

Carbohydrate adjuvants are safe and biocompatible compounds usable as sustained delivery systems and stimulants of ongoing humoral and cellular immune responses, being especially suitable for the development of vaccines against intracellular pathogens where alum is useless. The development of new adjuvants is difficult and expensive, however, in the last two years, seven new carbohydrate-based adjuvants have been patented, also there are twelve ongoing clinical trials of vaccines that contain carbohydrate-based adjuvants, as well as numerous publications on their mechanism of action and safety. More research is necessary to improve the existent adjuvants and develop innovative ones.

Promotion of Cellular and Humoral Immunity against Foot-and-Mouth Disease Virus by Immunization with Virus-Like Particles Encapsulated in Monophosphoryl Lipid A and Liposomes

Virus-like particles (VLPs) have emerged as promising vaccine candidates against foot-and-mouth disease (FMD). However, such vaccines provide a relatively low level of protection against FMD virus (FMDV) because of their poor immunogenicity. Therefore, it is necessary to design effective vaccine strategies that induce more potent immunogenicity. In order to investigate the means to improve FMD VLP vaccine (VLP_FMDV) immunogenicity, we encapsulated VLPs (MPL/DDA-VLP_FMDV) with cationic liposomes based on dimethyldioctadecylammonium bromide (DDA) and/or monophosphoryl lipid A (MPL, TLR4 agonist) as adjuvants. Unlike inactivated whole-cell vaccines, VLP_FMDV were successfully encapsulated in this MPL/DDA system. We found that MPL/DDA-VLP_FMDV could induce strong cell-mediated immune responses by inducing not only VLP-specific IFN-γ⁺CD4⁺ (Th1), IL-17A⁺CD4⁺ (Th17), and IFN-γ⁺CD8⁺ (activated CD8 response) T cells, but also the development of VLP-specific multifunctional CD4⁺ and CD8⁺ memory T cells co-expressing IFN-γ, TNF-α, and IL-2. In addition, the MPL/DDA-VLP_FMDV vaccine markedly induced VLP-specific antibody titers; in particular, the vaccine induced greater Th1-predominant IgG responses than VLP_FMDV only and DDA-VLP_FMDV. These results are expected to provide important clues for the development of an effective VLP_FMDV that can induce cellular and humoral immune responses, and address the limitations seen in current VLP vaccines for various diseases.

Anti-cervical carcinoma effect of Portulaca oleracea L. polysaccharides by oral administration on intestinal dendritic cells

BACKGROUND

Cervical cancer is the second most prevalent cancer worldwide. Portulaca oleracea L. polysaccharide (POL-P3b) has been found to have enhancing immune and anti-cervical cancer activity by oral administration. Dendritic cells (DC) play a key roles in regulating intestinal immune homeostasis. In this study, we analyzed the inhibition apoptosis effects of POL-P3b on intestinal DC and relevant mechanisms.

METHODS

Intestinal DC was isolated from U14-bearing mice treated with POL-P3b (50 mg/kg, 100 mg/kg and 200 mg/kg, respectively). The effects of POL-P3b on proliferation and inhibiting apoptosis in intestinal DC were evaluated by MTT assay, Hoechst 33342 and Annexin V-FITC/PI staining. Mitochondrial Ca²⁺ was analyzed using flow cytometry instrument. The potential mechanisms underlying POL-P3b-induced protection of intestinal DC from cervical cancer-induced apoptosis were detected with Western blotting evaluation of expression levels of TLR4 and relevant proteins for apoptotic signaling pathway.

RESULTS

We found that a large number of intestinal DC were apoptosis in U14-bearing mice. Treatment with POL-P3b in U14-bearing mice at different doses for 12 d resulted in a significant increase in intestinal DC survival, and the mechanisms were related to inhibiting DC apoptosis.

CONCLUSION

Our results suggested that POL-P3b-induced protection against tumor-induced intestinal DC apoptosis through stimulating the TLR4-PI3K/AKT-NF-κB signaling pathway. This study enhanced understanding of the oral administration with POL-P3b exerted on anti-tumor activity and its action mechanism.