The stimulatory effect of different CpG oligonucleotides on the maturation of chicken bone marrow-derived dendritic cells

Chondroitin sulfate-based prodrug nanoparticles enhance photodynamic immunotherapy via Golgi apparatus targeting

Photodynamic therapy (PDT) is an emerging therapeutic approach that can inhibit tumor growth by destroying local tumors and activating systemic antitumor immune responses. However, PDT can be ineffective because of photosensitizer aggregation, tumor-induced dendritic cells (DC_S) dysfunction and PDT-mediated immunosuppression. Therefore, we designed chondroitin sulfate-based prodrug nanoparticles for the co-delivery of the photosensitizer chlorin e6 (Ce6) and retinoic acid (RA), which can reduce PDT-mediated immunosuppression by disrupting the Golgi apparatus and blocking the production of immunosuppressive cytokines. Moreover, CpG oligodeoxynucleotide was combined as immunoadjuvant to promote the maturation of DCs. As expected, the strategy of Golgi apparatus targeting immunotherapy combined PDT was confirmed to relieve PDT-induced immunosuppression, showed excellent PDT antitumor efficacy in B16F10-subcutaneous bearing mice model. Thus, our finding offers a promising approach for photodynamic immunotherapy of advanced cancers. STATEMENT OF SIGNIFICANCE: Golgi apparatus has been shown to be a potential target of immunosuppression for producing several immunosuppressive cytokines. In this work, a Golgi apparatus-targeted prodrug nanoparticle was developed to enhance the immune response in photodynamic immunotherapy. The nanoparticle can target and disrupt the Golgi apparatus in tumor cells, which reduced PDT-mediated immunosuppression by blocking the production of immunosuppressive cytokines. This work provides an effective strategy of PDT in combination with the Golgi apparatus-targeted nanovesicle for enhanced cancer therapy.

Mucosal delivery of CpG-ODN mimicking bacterial DNA via the intrapulmonary route induces systemic antimicrobial immune responses in neonatal chicks

The transition to antibiotic-free poultry production in the face of pathogenic threats is a very challenging task. We recently demonstrated that mucosal delivery of CpG-ODN alone by the intrapulmonary route (IPL) has potential as an effective alternative to antibiotics in neonatal chicks against Escherichia coli septicemia. How exactly mucosal delivery of CpG-ODN elicits, protective antibacterial immunity remained poorly understood. In this study, CpG-ODN or saline was delivered via the intrapulmonary route to day-old chicks (n = 80/group) using a compressor nebulizer in an acrylic chamber (1 mg/mL CpG-ODN for 15 minutes). In the first part of the study, two days after mucosal CpG-ODN delivery, 40 chicks from each group were challenged subcutaneously with 1 × 10⁵ cfu (n = 20) or 1 × 10⁶ cfu (n = 20) of E. coli and the mortality pattern was monitored for seven days. We found significantly higher survival, better clinical conditions and lower bacterial loads in chicks that received mucosal CpG-ODN. To explore the mechanisms behind this protective immunity, we first looked at the kinetics of the cytokine gene expression (three birds/ group/ time for 10 time-points) in the lungs and spleens. Multiplex gene analysis demonstrated a significant elevation of pro-inflammatory cytokine genes mRNA in the CpG-ODN group. Interleukin (IL)-1β robustly upregulated many folds in the lung after CpG-ODN delivery. Lipopolysaccharide-induced tumor necrosis factor (LITAF) and IL-18 showed expression for an extended period in the lungs. Anti-inflammatory cytokine IL-10 was upregulated in both lungs and spleen, whereas IL-4 showed upregulation in the lungs. To investigate the kinetics of immune enrichment in the lungs and spleens, we performed flow cytometry, histology, and immunohistochemistry at 24, 48 and 72 hrs after CpG-ODN delivery. CpG-ODN treated lungs showed a significant enrichment with monocytes/macrophages and CD4⁺ and CD8⁺ T-cell subsets. Macrophages in CpG-ODN treated group demonstrated mature phenotypes (higher CD40 and MHCII expression). Importantly, mucosal delivery of CpG-ODN via the intrapulmonary route significantly enriched immune compartment in the spleen as well, suggesting a systemic effect in neonatal chicks. Altogether, intrapulmonary delivery of aerosolized CpG-ODN orchestrates protective immunity against E. coli septicemia by not only enhancing mucosal immunity but also the systemic immune responses.

Current knowledge about interactions between avian dendritic cells and poultry pathogens

In poultry production conditions today, birds are surrounded by viral, bacterial, and parasitic agents. DCs are the main antigen-presenting cells located in tissues of the body, and their role involves recognizing antigen structures, engulfing and processing them, and subsequently presenting antigen peptides on their surface by major histocompatibility complex, where T cells and B cells are stimulated and can begin appropriate cellular and antibody immune response. This unique function indicates that these cells can be used in producing vaccines, but first it is necessary to culture DCs in vitro to identify the principles of their interactions with pathogens. The following review summarizes our current knowledge about avian dendritic cells and their interactions with pathogens. It provides a basis for future studies of these unique cells and their use in vaccine development.

Significant body mass increase by oral administration of a cascade of shIL21-MSTN yeast-based DNA vaccine in mice

Base on the practical of MSTN-specific yeast-based protein vaccine in mice as described previously, this research was designed for developing a better DNA vaccine (a cascade of shIL21-MSTN yeast-based DNA vaccine) than solely MSTN yeast-based DNA vaccine to block the endogenous MSTN in the murine model. We first constructed the target vectors, including CMV-driven MSTN expression vector and a combined shIL21-MSTN vector which containing MSTN expression cassette and shIL21 (short hairpin RNA-IL21) expression cassette. After necessary validation, recombinant yeast vaccines harboring different vectors were well prepared. Subsequently, after 2-month administration, the MSTN-specific immune response was detected with western blots. The commercial ELISA assays indicated that the production of IL21 and IL6 were decreased compared with control groups. More importantly, the MSTN-specific antibody titer was much higher in the shIL21-MSTN group than MSTN group, which was consistent with the western blots result. The most important finding was significant body mass increased after oral administration of these yeast-based DNA vaccines, in which the shIL21-MSTN vaccine is slightly higher than the sole MSTN vaccine in mice. In this study, we confirmed the role of different MSTN-specific yeast-based DNA vaccines on increasing body mass in mice, to provide a good inspiration for livestock breeding through the new type of immunoregulatory method. On the other hand, we also detected the possible modulating role of shIL21 on the dendritic cell-mediated immune function which needs more practical application and deeper exploration.

Microarray analysis of infectious bronchitis virus infection of chicken primary dendritic cells

Background

Avian infectious bronchitis virus (IBV) is a major respiratory disease-causing agent in birds that leads to significant losses. Dendritic cells (DCs) are specialised cells responsible for sampling antigens and presenting them to T cells, which also play an essential role in recognising and neutralising viruses. Recent studies have suggested that non-coding RNAs may regulate the functional program of DCs. Expression of host non-coding RNAs changes markedly during infectious bronchitis virus infection, but their role in regulating host immune function has not been explored. Here, microarrays of mRNAs, miRNAs, and lncRNAs were globally performed to analyse how avian DCs respond to IBV.

Results

First, we found that IBV stimulation did not enhance the maturation ability of avian DCs. Interestingly, inactivated IBV was better able than IBV to induce DC maturation and activate lymphocytes. We identified 1093 up-regulated and 845 down-regulated mRNAs in IBV-infected avian DCs. Gene Ontology analysis suggested that cellular macromolecule and protein location (GO-BP) and transcription factor binding (GO-MF) were abundant in IBV-stimulated avian DCs. Meanwhile, pathway analysis indicated that the oxidative phosphorylation and leukocyte transendothelial migration signalling pathways might be activated in the IBV group. Moreover, alteration of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) was detected in IBV-stimulated avian DCs. In total, 19 significantly altered (7 up and 12 down) miRNAs and 101 (75 up and 26 down) lncRNAs were identified in the IBV-treated group. Further analysis showed that the actin cytoskeleton and MAPK signal pathway were related to the target genes of IBV-stimulated miRNAs. Finally, our study identified 2 TF-microRNA and 53 TF–microRNA–mRNA interactions involving 1 TF, 2 miRNAs, and 53 mRNAs in IBV-stimulated avian DCs.

Conclusions

Our research suggests a new mechanism to explain why IBV actively blocks innate responses needed for inducing immune gene expression and also provides insight into the pathogenic mechanisms of avian IBV.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5940-6) contains supplementary material, which is available to authorized users.

Intrapulmonary Delivery of CpG-ODN Microdroplets Provides Protection Against Escherichia coli Septicemia in Neonatal Broiler Chickens

Synthetic oligodeoxynucleotides (ODN) containing unmethylated cytosine phosphodiester guanine (CpG) motifs (CpG-ODN) are effective immunostimulatory agents against a variety of viral, bacterial, and protozoan diseases in different animals including poultry. We have recently demonstrated that in ovo injection of CpG-ODN confers protection in neonatal chickens against bacterial septicemias. The objective of this study was to investigate the effectiveness of needle-free intrapulmonary (IPL) delivery of CpG-ODN microdroplets against Escherichia coli infection in neonatal chicks. In the present study, we used 880 chicks in total keeping 40 chicks per group. Chicks were delivered CpG-ODN or saline by IPL at the day 1 of hatch. Three days later, chicks were challenged with two doses (1 × 10⁴ CFU, n = 20 or 1 × 10⁵ CFU, n = 20) of E. coli. Chicks treated with CpG-ODN by the IPL route had significantly lower clinical signs and bacterial load compared to the group treated with saline ( P < 0.05). CpG-ODN-treated groups were significantly protected against E. coli septicemia. We observed dose- and exposure time-dependent immunoprotective effects of IPL CpG-ODN in chicks. We found that IPL delivery of CpG-ODN can induce protective immunity as early as 6 hr that remains effective at least until day 5 post-treatment. Moreover, there were no adverse effects of IPL delivery of CpG-ODN on growth or mortality up to 42 days of age. Based on these findings, it can be suggested that CpG-ODN delivery by IPL route can be a promising alternative to antibiotics for inducing protective immunity in chicks during the critical first week of neonatal life.

Genome-wide profiling of chicken dendritic cell response to infectious bursal disease

BACKGROUND

Avian infectious bursal disease virus (IBDV) is a highly contagious, immunosuppressive disease of young chickens, which causes high mortality rates and large economic losses in the poultry industry. Dendritic cells (DCs), which are antigen-presenting cells, have the unique ability to induce both innate and acquired immune responses and may significantly influence virus pathogenicity. To understand the interaction between IBDV and DCs, a microarray was used to analyse the response of DCs infected by IBDV.

RESULTS

IBDV infection induced 479 upregulated and 466 downregulated mRNAs in chicken DCs. Analysis of Gene Ontology suggested that transcription from the RNA polymerase II promoter and the RNA biosynthetic process were enriched, and pathway analyses suggested that oxidative phosphorylation, as well as the T cell receptor and Interleukin-17 (IL-17) signalling pathways might be activated by IBDV infection. Moreover, microRNA (miRNA) and long non-coding RNA (lncRNA) alterations in IBDV-infected chicken DCs were observed. A total of 18 significantly upregulated or downregulated miRNAs and 441 significantly upregulated or downregulated lncRNAs were identified in IBDV-stimulated DCs. We constructed 42 transcription factor (TF)-miRNA-mRNA interactions involving 1 TF, 3 miRNAs, and 42 mRNAs in IBDV-stimulated DCs. Finally, we predicted the target genes of differentially expressed lncRNAs, and constructed lncRNA-mRNA regulatory networks.

CONCLUSIONS

The results of this study suggest a mechanism to explain how IBDV infection triggers an effective immune response in chicken DCs.

Lactobacillus rhamnosus GG modulates innate signaling pathway and cytokine responses to rotavirus vaccine in intestinal mononuclear cells of gnotobiotic pigs transplanted with human gut microbiota

Background

A better understanding of mechanisms underlying dose-effects of probiotics in their applications as treatments of intestinal infectious or inflammatory diseases and as vaccine adjuvant is needed. In this study, we evaluated the modulatory effects of Lactobacillus rhamnosus GG (LGG) on transplanted human gut microbiota (HGM) and on small intestinal immune cell signaling pathways in gnotobiotic pigs vaccinated with an oral attenuated human rotavirus (AttHRV) vaccine.

Results

Neonatal HGM transplanted pigs were given two doses of AttHRV on 5 and 15 days of age and were divided into three groups: none-LGG (AttHRV), 9-doses LGG (AttHRV + LGG9X), and 14-doses LGG (AttHRV + LGG14X) (n = 3–4). At post-AttHRV-inoculation day 28, all pigs were euthanized and intestinal contents and ileal tissue and mononuclear cells (MNC) were collected. AttHRV + LGG14X pigs had significantly increased LGG titers in the large intestinal contents and shifted structure of the microbiota as indicated by the formation of a cluster that is separated from the cluster formed by the AttHRV and AttHRV + LGG9X pigs. The increase in LGG titers concurred with significantly increased ileal HRV-specific IFN-γ producing T cell responses to the AttHRV vaccine reported in our previous publication, suggesting pro-Th1 adjuvant effects of the LGG. Both 9- and 14-doses LGG fed pig groups had significantly higher IkBα level and p-p38/p38 ratio, while significantly lower p-ERK/ERK ratio than the AttHRV pigs, suggesting activation of regulatory signals during immune activation. However, 9-doses, but not 14-doses LGG fed pigs had enhanced IL-6, IL-10, TNF-α, TLR9 mRNA levels, and p38 MAPK and ERK expressions in ileal MNC. Increased TLR9 mRNA was in parallel with higher mRNA levels of cytokines, p-NF-kB and higher p-p38/p38 ratio in MNC of the AttHRV + LGG9X pigs.

Conclusions

The relationship between modulation of gut microbiota and regulation of host immunity by different doses of probiotics is complex. LGG exerted divergent dose-dependent effects on the intestinal immune cell signaling pathway responses, with 9-doses LGG being more effective in activating the innate immunostimulating TLR9 signaling pathway than 14-doses in the HGM pigs vaccinated with AttHRV.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0727-2) contains supplementary material, which is available to authorized users.

A novel role for RGMa in modulation of bone marrow-derived dendritic cells maturation induced by lipopolysaccharide

Repulsive guidance molecule a (RGMa) is known to mediate immune responses and has been indicated to modulates T cell activation and autoimmune diseases by dendritic cells (DCs), which hints its significant function in the latter cells. The aim of our study, therefore, was to evaluate the function of RGMa in DC maturation. We found that small interfering RNA (siRNA) successfully silenced the expression of RGMa in DCs. Even after LPS stimulation, RGMa-silenced DCs displayed an immature morphology, characterized by small, round cells with a few cell processes and organelles, and many pinocytotic vesicles. In the presence of LPS, RGMa siRNA transfection markedly reduced levels of CD80, CD86, CD40, and MHC II expression, as well as the secretion of IL-12p70 and TNF-α. With LPS treatment, RGMa siRNA-transfected DCs also showed increased levels of IL-10 and endocytosis. Moreover, in the presence of LPS, RGMa siRNA-transfected DCs displayed a low ability to induce T cell proliferation and differentiation, compared with negative control (NTi)-transfected or control DCs (p<0.05 for both). We conclude that after LPS stimulation, RGMa siRNA-transfected DCs show immunoregulatory and tolerogenic characteristics, which provides new insights into the immune system.

Immune Responses to Virulent and Vaccine Strains of Infectious Bronchitis Viruses in Chickens

Infectious bronchitis (IB) is an acute and highly contagious chicken viral disease, causing severe economic losses to poultry producers worldwide. In the last few decades, infectious bronchitis virus (IBV) has been extensively studied, but knowledge of immune responses to virulent or vaccine strains of IBVs remains limited. This review focuses on fundamental aspects of immune responses against IBV, including the role of pattern recognition receptors (PRRs) in identification of conserved viral structures and the role of different components of innate immunity (e.g., heterophils, macrophages, dendritic cells, acute phase protein, and cytokines). Studies on adaptive immune activation and the role of humoral and cellular immunity in IBV clearance are also reviewed. Multiple interlinking immune responses are essential for protection against virulent IBVs, including passive, innate, adaptive, and effector T cells active at mucosal surfaces. Although the development of approaches for chicken transcriptome and proteome analyses have greatly helped the understanding of the underlying genetic mechanisms for immunity, there are still major knowledge gaps, such as the role of mucosal and cellular responses to IBVs. In view of recent reports of emergent IBV variants in many countries, there is renewed interest in a more complete understanding of poultry immune responses to both virulent and vaccine strains of IBVs. This will be critical for developing new vaccine or vaccination strategies and other intervention programs.

CpG oligonucleotides and Astragalus polysaccharides are effective adjuvants in cultures of avian bone-marrow-derived dendritic cells

1. The potential use of CpG oligodeoxynucleotides and/or Astragalus polysaccharide (APS) as adjuvants for the culture of chicken bone-marrow-derived dendritic cells (chBM-DCs) was investigated. 2. Chicken dendritic cells (DCs) were isolated and cultured in the presence of recombinant chicken granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4. The chBM-DC displayed typical DC morphology and expressed DC surface markers (MHC-II and CD11c). 3. Cultured chBM-DC showed effective T-cell activation in vitro, based on a mixed lymphocyte response (MLR). Flow cytometry analysis showed an increased proportion of cells expressing CD40 and CD80 in the APS-stimulated culture, compared to the control culture. In the MLR, the APS- and CpG-stimulated chBM-DC could activate T-cells more than control chBM-DC. Real-time PCR assays showed that CpG can activate the TLR21 and an inflammatory response, while APS just reduced the expression of IRF-3. 4. The results demonstrated that in vitro the adjuvant CpG can stimulate chBM-DC to mature by activation of the TLR-signalling pathway, whereas the adjuvant APS stimulates maturation of chBM-DC in vitro to a lesser degree and by another mechanism.

Chicken bone marrow-derived dendritic cells maturation in response to infectious bursal disease virus

Infectious bursal disease virus (IBDV) is highly contagious disease which easily lead to immunosuppression and a decreased response to vaccinations in young chicken. Since dendritic cells (DCs) are crucial to induce immunity and their maturation and functions are influenced by microbial and environmental stimuli, we investigated the effects of inactivated IBDV and IBDV on chicken DC activation and maturation. Chicken bone marrow-derived dendritic cells (chBM-DCs) cultured in complete medium (including recombinant chicken: granulocyte-macrophage colony-stimulating factor and interleukin 4) expressed high levels of MHC-II and the putative CD11c. After LPS or virus stimulation, chBM-DCs displayed the typical morphology of DCs. In addition, stimulation by LPS or viruses significantly elevated chBM-DCs surface expression levels of CD40 and CD86 molecules, as well as the ability to induce T-cell proliferative response, compared to the non-stimulated chBM-DCs. Interestingly, inactive IBDV showed stronger ability to up-regulate expression levels of CD40 and CD86 molecules and stimulate naive T cells proliferation than live IBDV. These results revealed that live viruses infection impaired DC maturation and functions, probably explaining why chickens infected with IBDV fails to trigger an effective specific immune response or develop immune memory.