Evaluation and characteristics of immunological adjuvant activity of purified fraction of Albizia julibrissin saponins

Protection efficacy and the safety of the synergy between modified Bazhen powder and PRRSV modified-live virus vaccine against HP-PRRSV in piglets

The highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) poses a significant threat to the global swine industry. Vaccination is a preventive measure against viral infections. However, the use of vaccines in livestock healthcare programs faces the challenge of safety and delayed immune responses. Earlier studies have shown the potential of modified Bazhen powder as an immunomodulator with significant biological properties, but its effect on vaccines against HP-PRRSV is yet to be studied. This study elucidated how modified Bazhen powder could improve the safety and efficacy of the conventional PRRSV vaccine by evaluating T-cell responses, antibody levels, clinical symptoms, levels of viremia, organ health, and cytokine production. The results revealed that the oral application of modified Bazhen powder in combination with PRRS vaccination improved both cellular and humoral immunity, accelerated viremia clearance, improved lung injury scores, and reduced viral load in the tonsils. The modified Bazhen powder also effectively reduced inflammatory responses following a PRRSV challenge. These findings further highlight the pharmacological properties of modified Bazhen powder as a potential oral immunomodulatory agent that could enhance vaccine efficacy and ensure broad-spectrum protection against HP-PRRSV in pigs.

Mechanism of Innate Immune Response Induced by Albizia julibrissin Saponin Active Fraction Using C2C12 Myoblasts

Albizia julibrissin saponin active fraction (AJSAF), is a prospective adjuvant with dual Th1/Th2 and Tc1/Tc2 potentiating activity. Its adjuvant activity has previously been proven to be strictly dependent on its spatial co-localization with antigens, highlighting the role of local innate immunity in its mechanisms. However, its potential targets and pathways remain unclear. Here, its intracellular molecular mechanisms of innate immune response were explored using mouse C2C12 myoblast by integrative analysis of the in vivo and in vitro transcriptome in combination with experimental validations. AJSAF elicited a temporary cytotoxicity and inflammation towards C2C12 cells. Gene set enrichment analysis demonstrated that AJSAF regulated similar cell death- and inflammatory response-related genes in vitro and in vivo through activating second messenger-MAPK-CREB pathways. AJSAF markedly enhanced the Ca2+, cAMP, and reactive oxygen species levels and accelerated MAPK and CREB phosphorylation in C2C12 cells. Furthermore, Ca2+ chelator, CREB inhibitor, and MAPK inhibitors dramatically blocked the up-regulation of IL-6, CXCL1, and COX2 in AJSAF-treated C2C12 cells. Collectively, these results demonstrated that AJSAF induced innate immunity via Ca2+-MAPK-CREB pathways. This study is beneficial for insights into the molecular mechanisms of saponin adjuvants.

A comparison review of Hehuan flowers and Hehuan bark on the traditional applications, phytochemistry and pharmacological effects

ETHNOPHARMACOLOGICAL RELEVANCE

Albizia julibrissin Durazz is a well-known medicinal plant with the Chinese name Hehuan []. Hehuan bark and Hehuan flowers have long been recognized as traditional Chinese herbal medicine for treating anxiety, melancholy, insomnia, bruises, pulmonary abscess, fractures, carbuncle, amnesia, acute conjunctivitis, blurred vision, neonatal tetanus and stroke for thousands of years. They are recorded in Chinese Pharmacopoeia separately with different properties. Until now, new chemical constituents and pharmacological activities of Hehuan have been continuously studied and revealed.

THE AIM OF THE REVIEW

This review aims to provide a comprehensive summary of traditional applications, phytochemistry, pharmacology effects, and toxicology of Hehuan bark and Hehuan flowers, and give critical assessment and point out the promising direction for further research on Hehuan.

MATERIAL AND METHODS

A literature search was undertaken on Hehuan bark and Hehuan flowers by analyzing the information from scientific databases (SciFinder, Pubmed, Elsevier, Google Scholar, Web of Science, and Baidu Scholar). We also gathered the information of Hehuan from classic herbal literatures and conference papers on ethnopharmacology.

RESULTS

According to Chinese and English documents, the medicinal history of Hehuan in China can be traced back to ad 25. Meanwhile, its medicinal history as a kind of herbal medicine can also be found in other Asian countries. So far about 140 compounds have been isolated from Hehuan bark and Hehuan flowers, including triterpenoids, flavonoids, lignans, phenolic acids, alkaloids, etc. Among them, flavonoids mainly exist in Hehuan flowers, while Hehuan bark contains lignans and saponins. The composition differences between the barks and flowers of Hehuan account for the different effects and applications. Modern pharmacological studies have indicated that crude extracts and pure compounds of Hehuan flowers and Hehuan bark have multiple pharmacological activities, such as antineoplastic, immunomodulatory, anti-inflammatory, anxiolytic, antidepressant, metabolic regulation, anti-insomnia, neuroprotective, hepatoprotective, sedative, and anti-osteolytic activities.

CONCLUSIONS

Hehuan (Albizia julibrissin Durazz) is traditionally used to relieve depression, calm nerves, promote blood circulation and reduce swelling. Modern pharmacological studies have revealed that natural products from Hehuan bark and Hehuan flowers possess extensive pharmacological activities in treating cancer, enhancing immunity, regulating metabolism, improving mental state, etc. These properties make it great clinical application potential. Further research on natural pharmaceutical chemistry, pharmacology, toxicology, pharmacokinetics, and quality standards of Hehuan are still required to verify the efficacy and safety for future clinical applications.

Adjuvant activity of tubeimosides by mediating the local immune microenvironment

Rhizoma Bolbostemmatis, the dry tuber of Bolbostemma paniculatum, has being used for the treatment of acute mastitis and tumors in traditional Chinese medicine. In this study, tubeimoside (TBM) I, II, and III from this drug were investigated for the adjuvant activities, structure-activity relationships (SAR), and mechanisms of action. Three TBMs significantly boosted the antigen-specific humoral and cellular immune responses and elicited both Th1/Th2 and Tc1/Tc2 responses towards ovalbumin (OVA) in mice. TBM I also remarkably facilitated mRNA and protein expression of various chemokines and cytokines in the local muscle tissues. Flow cytometry revealed that TBM I promoted the recruitment and antigen uptake of immune cells in the injected muscles, and augmented the migration and antigen transport of immune cells to the draining lymph nodes. Gene expression microarray analysis manifested that TBM I modulated immune, chemotaxis, and inflammation-related genes. The integrated analysis of network pharmacology, transcriptomics, and molecular docking predicted that TBM I exerted adjuvant activity by interaction with SYK and LYN. Further investigation verified that SYK-STAT3 signaling axis was involved in the TBM I-induced inflammatory response in the C2C12 cells. Our results for the first time demonstrated that TBMs might be promising vaccine adjuvant candidates and exert the adjuvant activity through mediating the local immune microenvironment. SAR information contributes to developing the semisynthetic saponin derivatives with adjuvant activities.

Panax Notoginseng Saponins Suppress Type 2 Porcine Reproductive and Respiratory Syndrome Virus Replication in vitro and Enhance the Immune Effect of the Live Vaccine JXA1-R in Piglets

Porcine reproductive and respiratory syndrome virus (PRRSV) suppresses the innate immune response in the host, reducing and delaying neutralizing antibody production against PRRSV infection and promoting viral infection. Here, we aimed to assess the potential of Panax notoginseng saponins (PNS) for improving the immune response exerted upon PRRSV-2-modified live virus (MLV) vaccine administration. Thirty piglets were randomly divided into six groups. Group 1 piglets were injected with medium 0 days post vaccination (dpv). Group 2 piglets were fed PNS 0–28 dpv. Group 3 and group 4 piglets were administered the JXA1-R vaccine 0 dpv. Group 4 piglets were also fed PNS 0–28 dpv. Group 1–4 piglets were challenged intranasally with the PRRSV JXA1 strain 28 dpv. Group 5 piglets were fed with PNS without challenge. Group 6 piglets served as controls. During the experiment, the samples were collected regularly for 49 days. Compared with group 1 piglets, group 3 piglets showed significantly reduced viremia and clinical scores, and significantly increased average daily gain (ADWG). Compared with group 3 piglets, group 4 piglets showed significantly improved neutralizing antibody titers, IFN-α and IFN-β mRNA expression, and significantly decreased viremia and viral load in the lungs and lymph nodes, but did not demonstrate any further improvement in PRRSV-specific antibody titer, rectal temperature, ADWG, or clinical scores. PNS upregulates neutralizing antibodies against PRRSV-2 and enhances the expression of IFN-α and IFN-β, which may reduce PRRSV viremia upon PRRSV-2 MLV vaccine administration. PNS may serve as an effective immunomodulator for boosting the immune defense against PRRSV.

Adjuvant effect of two polysaccharides from the petals of Crocus sativus and its mechanisms

Two polysaccharides from Crocus sativus petals (PCSPs), PCSPA and PCSPB, presented immunopotentiatory activity through activating macrophages via MAPK and NF-κB pathway. In this study, two PCSPs were investigated for the adjuvant effects and underlying mechanisms using ovalbumin (OVA) in mice. PCSPA and PCSPB remarkably not only boosted the OVA-specific IgG antibody and its isotype titers, but strengthened splenocyte proliferation and natural killer cell activities in immunized mice. Both PCSPs also dramatically triggered the production of Th1- and Th2-cytokines and facilitated the gene expression of Th1- and Th2-cytokines and transcription factors in OVA-stimulated splenocytes. In mechanisms, two PCSPs rapidly elicited the gene and protein expression of cytokines and chemokines, promoted the recruitment and antigen uptake of immune cells in the injected-muscles, and augmented the migration and antigen transport of immune cells to the draining lymph nodes. These findings demonstrated that PCSPs enhanced and improved immune responses and simultaneously elicited Th1- and Th2-immune responses to OVA through activating innate immune microenvironment, and that they could act as promising vaccine adjuvant candidates.

Generation and Evaluation of Recombinant Baculovirus Coexpressing GP5 and M Proteins of Porcine Reproductive and Respiratory Syndrome Virus Type 1

Porcine reproductive and respiratory syndrome virus (PRRSV) is the pathogen of the porcine reproductive and respiratory syndrome, which is one of the most economically devastating diseases of the swine industry. However, whether the inactivated vaccine and modified live attenuated vaccines are effective in disease control is still controversial. Although several groups developed PRRSV virus-like particles (VLPs) as a vaccine against PRRSV, all these VLP-based vaccines targeted PRRSV-2, but not PRRSV-1 or both. Therefore, it is urgent to produce VLPs against PRRSV-1. In this study, we rescued recombinant baculovirus expressing GP5 and M proteins of PRRSV-1 through the Bac-to-Bac^® baculovirus expression system. Thereafter, PRRSV VLP was obtained efficiently in the recombinant baculovirus-infected High Five insect cells. Moreover, the PRRSV VLP and PRRSV VLP+A5 could efficiently trigger specific humoral immune responses and B cellular immune responses through intranasal immunization. The combination of PRRSV VLP and A5 adjuvant could improve the level of the immune response. The PRRSV-1 VLPs generated in this study have greater potential for vaccine development to control PRRSV-1 infection.

Co-expression network analysis identifies innate immune signatures for Albizia julibrissin saponin active fraction-adjuvanted avian influenza vaccine

Albizia julibrissin saponin active fraction (AJSAF) is a promising adjuvant candidate, but its innate immune response mechanisms remain unclear. Here, the quadriceps muscles from the mice injected intramuscularly with AJSAF alone or in combination with ovalbumin and avian influenza vaccine (rL-H5) were subjected to gene microarray. Antigen- and AJSAF-related modules with intramodular hub genes were identified and functionally analyzed using weighted gene co-expression network analysis (WGCNA) and gene set enrichment analysis (GSEA). AJSAF induced early innate immune responses at the injection site, characterized by cytokine production and neutrophil recruitment. AJSAF mainly elicited the expression of "Th1 immune response" and "Neutrophils" genes such as CCL2, CXCL1, CXCL5, IL-1β, IL-6, IL-33, S100A8, and S100A9, whereas these two gene sets were negatively enriched for rL-H5. AJSAF-specific long noncoding RNAs MIRT1 and MIRT2 could function as inflammatory mediators, whereas function unknown TINCR was co-expressed with immune response genes including CCL2, CCL4, CCL7, CSF3, CXCL5, IL-33, S100A8, and S100A9. Finally, the innate immune molecular mechanisms of adjuvant action of AJSAF and the potential signatures were proposed. These findings expanded the current knowledge on the mechanisms of action of saponin-based adjuvants.

Quick and improved immune responses to inactivated H9N2 avian influenza vaccine by purified active fraction of Albizia julibrissin saponins

Background

H9N2 Low pathogenic avian influenza virus (LPAIV) raises public health concerns and its eradication in poultry becomes even more important in preventing influenza. AJSAF is a purified active saponin fraction from the stem bark of Albizzia julibrissin. In this study, AJSAF was evaluated for the adjuvant potentials on immune responses to inactivated H9N2 avian influenza virus vaccine (IH9V) in mice and chicken in comparison with commercially oil-adjuvant.

Results

AJSAF significantly induced faster and higher H9 subtype avian influenza virus antigen (H9–Ag)-specific IgG, IgG1, IgG2a and IgG2b antibody titers in mice and haemagglutination inhibition (HI) and IgY antibody levels in chicken immunized with IH9V. AJSAF also markedly promoted Con A-, LPS- and H9–Ag-stimulated splenocyte proliferation and natural killer cell activity. Furthermore, AJSAF significantly induced the production of both Th1 (IL-2 and IFN-γ) and Th2 (IL-10) cytokines, and up-regulated the mRNA expression levels of Th1 and Th2 cytokines and transcription factors in splenocytes from the IH9V-immunized mice. Although oil-formulated inactivated H9N2 avian influenza vaccine (CH9V) also elicited higher H9–Ag-specific IgG and IgG1 in mice and HI antibody titer in chicken, this robust humoral response was later produced. Moreover, serum IgG2a and IgG2b antibody titers in CH9V-immunized mice were significantly lower than those of IH9V alone group.

Conclusions

AJSAF could improve antigen-specific humoral and cellular immune responses, and simultaneously trigger a Th1/Th2 response to IH9V. AJSAF might be a safe and efficacious adjuvant candidate for H9N2 avian influenza vaccine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-020-02648-1.

The ethnopharmacology, phytochemistry, pharmacology and toxicology of genus Albizia: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Albizia (Leguminosae) comprises about 150 species and some species have been used for the treatment of rheumatism, stomachache, cough, diarrhea, and wounds in traditional and local medicine. The aim of the review: This review article documents and critically assesses the current status of the traditional uses, phytochemistry, pharmacology, and toxicology of the Albizia species.

MATERIALS AND METHODS

All provided literatures on the Albizia species were searched using the electronic databases (e.g. Web of Science, Elsevier, Springer, PubMed, ACS, CNKI, Google Scholar, and Baidu Scholar), books, and theses with keywords of 'Albizia' and 'Albizzia'.

RESULTS

Albizia species have been used for melancholia, insomnia, wounds, fever, abscesses, diabetes, headache, stomachache, diarrhea, cough, rheumatism, snake bite, malaria, and parasitic infection in traditional and local medicine. These plants mainly contain triterpenoid saponins, flavonoids, lignanoids, alkaloids, phenolic glycosides, etc. Albizia species have been demonstrated to possess various pharmacological activities. Among them, the antidiabetic, anti-inflammatory, antifertility, antianxiety, antidepressant, and anti-fever properties are consistent with the traditional and local applications of the Albizia species.

CONCLUSIONS

The traditional and local uses of Albizia species have been partially demonstrated by the pharmacological investigation. However, some traditional applications have not been assessed scientifically due to incomplete methodologies and ambiguous findings. Moreover, no clinical evidences support the health benefits of these plants. The systematic and comprehensive preclinical studies and clinical trials are still required to verify the pharmacological activities, clinical efficacy, and safety of Albizia species.

Intranasal delivery of cationic liposome-protamine complex mRNA vaccine elicits effective anti-tumor immunity

Immunization with synthetic mRNA encoding tumor-associated antigens is an emerging vaccine strategy for the treatment of cancer. In order to prevent mRNA degradation, promote antigen-presenting cells antigen presentation, and induce an anti-tumor immune response, we investigated the nasal administration of mRNA vaccines with positively charged protamine to concentrate mRNA, form a stable polycation-mRNA complex, and encapsulate the complex with DOTAP/Chol/DSPE-PEG cationic liposomes. Cationic liposome/protamine complex (LPC) showed significantly greater efficiency in uptake of vaccine particles in vitro and stronger capacities to stimulate dendritic cell maturation, which further induced a potent anti-tumor immune response. Intranasal immunization of mice with cationic LPC containing mRNA encoding cytokeratin 19 provoked a strong cellular immune response and slowed tumor growth in an aggressive Lewis lung cancer model. The results of this study provide evidence that cationic LPC can be used as a safe and effective adjuvant and this mRNA formulation provides a basis for anti-cancer vaccination of humans.

Mechanisms of Mixed Th1/Th2 Responses in Mice Induced by Albizia julibrissin Saponin Active Fraction by in Silico Analysis

The purified active fraction of Albizia julibrissin saponin (AJSAF) is an ideal adjuvant candidate that improves antigen-specific both cellular and humoral immune responses and elicits mixed Th1/Th2 responses, but its mechanisms remain unclear. The key features of action of AJSAF were investigated in mice immunized with Newcastle disease virus-based recombinant influenza vaccine (rL-H5) and AJSAF at the same leg (AJSAF+rL-H5) or different legs (AJSAF/rL-H5). The adjuvant activity of AJSAF on rL-H5 is strictly dependent on their spatial colocalization. Serum H5 antigen (H5Ag)-specific IgG, IgG1, IgG2a, and IgG2b antibody titers in AJSAF+rL-H5 group were significantly higher than those in AJSAF/rL-H5 group. The mechanisms of selectivity of Th1 or Th2 in mice induced by AJSAF was explored by the transcriptomic and proteomic profiles of H5Ag-stimulated splenocytes from the immunized mice using gene microarray and two-dimensional difference gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Compared to rL-H5 alone, AJSAF/rL-H5 induced more differentially expressed genes (DEGs) than AJSAF+rL-H5, whereas AJSAF+rL-H5 upregulated higher mRNA expression of Th1 (T-bet, IFN-γ, TNF-α, IL-12β, and IL-12Rβ1) and Th2 (IL-10 and AICDA) immune response genes. The neutrophil response and its derived S100A8 and S100A9 might be involved in the AJSAF-mediated Th1 response. Meanwhile, AJSAF might induce the adaptive immune responses by improving a local innate immune microenvironment. These findings expanded the current knowledge on the mechanisms of action of saponin-based adjuvants, and provided new insights into how adjuvants shape adaptive immune responses.

Rapid annotation and structural characterization of saponins in the active fraction of Albizia julibrissin by high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry based on accurate mass database

The purified active fraction of Albizia julibrissin saponin was proved to be a promising adjuvant candidate for vaccine. In this study, a simple, convenient, and practical strategy was established for characterizing the saponins in this purified active fraction. The personal accurate mass database including chemical structure, molecular formula, and theoretical mass was first constructed by collecting 110 reported known saponins from genus Albizia species. The raw data was obtained by high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry. The potential compounds were extracted from raw data, and matched with the accurate mass databases. A series of saponin compounds were predicted and their chemical structures were characterized by interpreting the tandem mass spectrometry data. A total of 29 saponins including 10 new compounds and 5 first found saponins from A. julibrissin were successfully characterized in this purified active fraction using this new strategy.