Role of Hsp90 in CpG ODN mediated immunostimulation in avian macrophages

Gene expression profiling of RIP2-knockdown in HD11 macrophages - elucidation of potential pathways (gene network) when challenged with avian pathogenic E.coli (APEC)

BACKGROUND

Receptor interacting serine/threonine kinase 2 (RIP2), ubiquitous in many tissue/cell types, is the key regulator of immune and inflammatory responses for many diseases, including avian pathogenic E. coli (APEC), which causes a wide variety of localized or systemic infections. However, the molecular mechanisms by which RIP2 drives its transcriptional program to affect immune and inflammatory response upon APEC infection remains poorly understood.

RESULTS

In this study, RNA-seq and bioinformatics analyses were used to detect gene expression and new direct/indirect RIP2 targets in the treatments of wild type HD11 cells (WT), RIP2 knockdown cells (shRIP2), APEC stimulation cells (APEC), and RIP2 knockdown cells combined with APEC infection (shRIP2 + APEC). The results revealed that a total of 4691 and 2605 differentially expressed genes (DEGs) were screened in shRIP2 + APEC vs. APEC and shRIP2 vs. WT, respectively. Functional annotation analysis showed that apoptosis, MAPK, p53, Toll-like receptor, and Nod-like receptor signaling pathways were involved in APEC-induced RIP2 knockdown HD11 cells. By analyzing the enriched pathway and gene networks, we identified that several DEGs, including HSP90AB1, BID, and CASP9 were targeted by RIP2 upon APEC infection.

CONCLUSION

As a whole, this study can not only provide data support for constructing gene networks of RIP2 knockdown with APEC challenge but also provide new ideas for improving the immune and inflammatory response.

Comprehensive transcriptional changes in the liver of Kanglang white minnow (Anabarilius grahami) in response to the infection of parasite Ichthyophthirius multifiliis

Simple Summary

Kanglang white minnow (KWM, Anabarilius grahami), is a typical “3E” (Endangered, Endemic and Economic) fish species in Yunnan-Guizhou Plateau. As one of the traditional “Four Famous Fishes” in Yunnan province, it has become the major local aquaculture species with increasing demand after the success of artificial breeding. However, this economically important fish is highly susceptible to the infection of a parasite ciliate, Ichthyophthirius multifiliis (Ich), during the practical procedure of artificial breeding. To examine the host immune responses to Ich, we divided the experimental fishes into three groups (including control, early-infected stage, and late-infected stage) for transcriptome sequencing to analyze the differentially expressed genes (DEGs) and immune response mechanisms.

Abstract

The notorious parasite Ichthyophthirius multifiliis (Ich) has been recorded worldwide in fish species and causes white spot disease, posing major threats and resulting in severe losses to international fish production. Extensively effective strategies for treating Ich are not available yet, and genetic mechanisms of hosts in response to the parasite are still largely unknown. In this study, we selected Kanglang white minnow (KWM, Anabarilius grahami) to examine its liver transcriptional changes after Ich infection, as white spot disease is one bottleneck problem in exploring this economically important species. We divided the experimental fishes into three groups (control, early-infected, and late-infected) to examine differentially expressed genes (DEGs). A total of 831 DEGs were identified and classified into 128 significantly enriched GO (Gene Ontology) terms and 71 significantly enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways. Most of these terms or pathways were functionally enriched in immunity, inflammatory response, and apoptosis, such as nucleotide-binding oligomerization domain-like (NOD-like) receptor signaling, tumor necrosis factor (TNF) signaling, interleukin-17 (IL-17) signaling, and apoptosis pathways. We also identified 178 putative antimicrobial peptides (AMPs) and AMP precursors based on our previously reported genome assembly of KWM, and revealed that the expressional patterns varied according to different types. In summary, our work reported the first comprehensive transcriptional changes in KWM in response to the exogenous infection of Ich, which would lay a solid foundation for in-depth studies on disease defense or resistant strains selection in this valuable fish.

In ovo CpG DNA delivery increases innate and adaptive immune cells in respiratory, gastrointestinal and immune systems post-hatch correlating with lower infectious laryngotracheitis virus infection

Cytosine-guanosine deoxynucleotides (CpG) DNA can be delivered in ovo at embryo day (ED)18 for the stimulation of toll-like receptor (TLR)21 signaling pathway that ultimately protects chickens against a number of bacterial and viral infections. There is a dearth of information understanding the mechanisms of protection induced by in ovo delivered CpG DNA. The objective of this study was to determine the immune cell changes post-hatch following in ovo delivery of the TLR21 ligand, CpG DNA. In order to quantify changes of percentage of KUL01+, IgM+ B, cluster of differentiation (CD)4+ and CD8α+ cells, trachea, lung, duodenum, large intestine, spleen and bursa of Fabricius were collected on day 1 post-hatch. We found increased recruitments of KUL01+ cells, in organs of these body systems post-hatch following in ovo delivery of CpG DNA. Although IgM+ B cells, CD4+ and CD8α+ cells were increased in lungs and immune system organs, these cells were not quantifiable from the trachea, duodenum and large intestine immediately following the hatch. Furthermore, when CpG DNA is delivered in ovo and subsequently infected with infectious laryngotracheitis virus (ILTV) post-hatch on day 1, CpG DNA reduces morbidity and mortality resulting from ILTV infection. This study provides insights into the mechanisms of host responses elicited following in ovo delivery of CpG DNA in avian species.

Toll-like receptor (TLR)21 signalling-mediated antiviral response against avian influenza virus infection correlates with macrophage recruitment and nitric oxide production

Cytosine-guanosinedeoxynucleotide (CpG) DNA can be used for the stimulation of the toll-like receptor (TLR)21 signalling pathway in avian species which ultimately leads to up-regulation of gene transcription for pro-inflammatory molecules including nitric oxide and recruitment of innate immune cells. The objective of this study was to determine the antiviral effect of NO, produced in response to in ovo delivery of CpG DNA, against avian influenza virus (AIV) infection. We found that when CpG DNA is delivered at embryo day (ED)18 in ovo and subsequently challenged with H4N6 AIV at ED19 pre-hatch and day 1 post-hatching, CpG DNA reduces H4N6 AIV replication associated with enhanced NO production and macrophage recruitment in lungs. In vitro, we showed that NO originating from macrophages is capable of eliciting an antiviral response against H4N6 AIV infection. This study provides insights into the mechanisms of CpG DNA-mediated antiviral response, particularly against AIV infection in avian species.

The effects of subcutaneous and intraocular administration of class B ODN CpG in chicken on the expression of TLR21, IFN-γ and IL-1β

The synthetic unmethylated oligodeoxynucleotides with CpG motifs (CpG ODN) were shown to activate Toll-like receptor 21 (TLR21) and stimulate the innate and adaptive immune system. In this study we tested the expression of TLR21, interferon (IFN)-γ and interleukin (IL)-1β mRNA in the blood after subcutaneous and intraocular application of the class B CpG ODN in chicken. The relative expression of mRNA of TLR21, IFN-γ and IL-1β were quantified at 3, 6, 12, 24 and 72 h post-stimulation. The study revealed that IFN-γ mRNA expression was significantly upregulated 12 h after subcutaneous stimulation with a high and low dose of ODN CpG, whereas the IL-1β mRNA expression levels were significantly upregulated 3 and 72 h after subcutaneous administration. After intraocular administration, the IL-1β mRNA levels were the highest at 24 h post-application, albeit not specifically. This data indicates that class B CpG ODN has the ability to induce TLR21 response in blood when administered parenterally in chicken. In contrast, intraocular administration of CpG ODN was not able to produce a significant increase in cytokine mRNA expression in blood. The data suggest that additional stimulus, e.g. the antigen, may be needed on the site of mucosal administration to activate systemic immune response.

Class B CpG ODN stimulation upregulates expression of TLR21 and IFN-γ in chicken Harderian gland cells

This study aimed to evaluate the response of Harderian gland (HG) cells after in vitro stimulation with class B synthetic oligodeoxyribonucleotides (ODN) containing CpG motifs. This knowledge is of importance for the development of mucosal vaccines for poultry, such as eye-drop or spray vaccines, to determine if class B CpG ODN can act as an vaccine adjuvant or as a prophylactic treatment mainly against respiratory disease viruses. The relative expression of Toll-like receptor 21 (TLR21), interferon (IFN)-γ, interleukin (IL)-1β and IL-10 genes were quantified at 1, 3, 6 and 18 h post-stimulation of HG cells from 5-week-old birds. In addition, it was also investigated if expression of these genes was affected by the age of the birds (differences between 5- and 12-week-old birds), concentrations of ODN or cell preparation method used. Class B CpG ODN induced upregulation of TLR21 and IFN-γ mRNA expression levels at 1h post-stimulation depending on concentration of ODN used but only in HG cells isolated from young birds.

Co-stimulation with TLR3 and TLR21 ligands synergistically up-regulates Th1-cytokine IFN-γ and regulatory cytokine IL-10 expression in chicken monocytes

Toll-like receptors (TLRs) are pattern recognition receptors of the innate immune system for various conserved pathogen-associated molecular motifs. Chicken TLR3 and TLR21 (avian equivalent to mammalian TLR9) recognize poly I:C (double-stranded RNA) and CpG-ODN (a CpG-motif containing oligodeoxydinucleotide), respectively. Interaction between TLR3 and TLR21 agonists poly I:C and CpG-ODN has been reported to synergize in expression of proinflammatory cytokines and chemokines and the production of nitric oxide in chicken monocytes. However, the interaction between poly I:C and CpG-ODN on the expression of interferons (IFNs) and Th1/Th2 cytokines remains unknown. The objective of the present study was to investigate the effect of the interaction between poly I:C and CpG-ODN on the mRNA expression levels of IFN-α and IFN-β, Th1 cytokines IFN-γ and IL-12, Th2 cytokine IL-4, and regulatory IL-10 in chicken monocytes. When stimulated with either agonist alone, CpG-ODN significantly up-regulated the expression of INF-γ, IL-10, and IL-12p40, but not IFN-α and IFN-β; whereas poly I:C induced the expression of INF-γ, IFN-α, IFN-β, and IL-10; but not IL-12p40. However, stimulation with a combinatory CpG-ODN and poly I:C further synergistically increased the expression of IFN-γ and IL-10 mRNA. Our results provide strong evidence supporting the critical role of TLR3 and TLR21 in avian innate immunity against both viral and bacterial infections; and the synergistic interaction between the TLR3 and TLR21 pathways produces a stronger Th1-biased immune response in chicken monocytes. Our result also suggest a potential use of poly I:C and CpG-ODN together as a more efficient adjuvant for poultry vaccine development.

Modulation of chicken macrophage effector function by T(H)1/T(H)2 cytokines

Regulation of macrophage activity by T(H)1/2 cytokines is important to maintain the balance of immunity to provide adequate protective immunity while avoiding excessive inflammation. IFN-γ and IL-4 are the hallmark T(H)1 and T(H)2 cytokines, respectively. In avian species, information concerning regulation of macrophage activity by T(H)1/2 cytokines is limited. Here, we investigated the regulatory function of chicken T(H)1 cytokines IFN-γ, IL-18 and T(H)2 cytokines IL-4, IL-10 on the HD11 macrophage cell line. Chicken IFN-γ stimulated nitric oxide (NO) synthesis in HD11 cells and primed the cells to produce significantly greater amounts of NO when exposed to microbial agonists, lipopolysaccharide, lipoteichoic acid, peptidoglycan, CpG-ODN, and poly I:C. In contrast, chicken IL-4 exhibited bi-directional immune regulatory activity: it activated macrophage NO synthesis in the absence of inflammatory agonists, but inhibited NO production by macrophages in response to microbial agonists. Both IFN-γ and IL-4, however, enhanced oxidative burst activity of the HD11 cells when exposed to Salmonella enteritidis. IL-18 and IL-10 did not affect NO production nor oxidative burst in HD11 cells. Phagocytosis and bacterial killing by the HD11 cells were not affected by the treatments of these cytokines. Infection of HD11 cells with S.enteritidis was shown to completely abolish NO production regardless of IFN-γ treatment. This study has demonstrated that IFN-γ and IL-4 are important T(H)1 and T(H)2 cytokines that regulate macrophage function in chickens.