Toll-like receptor (TLR)4 signalling induces myeloid differentiation primary response gene (MYD) 88 independent pathway in avian species leading to type I interferon production and antiviral response

The Mechanisms of Polysaccharides from Tonic Chinese Herbal Medicine on the Enhancement Immune Function: A Review

Tonic Chinese herbal medicine is a type of traditional Chinese medicine, and its primary function is to restore the body's lost nutrients, improve activity levels, increase disease resistance, and alleviate physical exhaustion. The body's immunity can be strengthened by its polysaccharide components, which also have a potent immune-system-protecting effect. Several studies have demonstrated that tonic Chinese herbal medicine polysaccharides can improve the body's immune response to tumor cells, viruses, bacteria, and other harmful substances. However, the regulatory mechanisms by which various polysaccharides used in tonic Chinese herbal medicine enhance immune function vary. This study examines the regulatory effects of different tonic Chinese herbal medicine polysaccharides on immune organs, immune cells, and immune-related cytokines. It explores the immune response mechanism to understand the similarities and differences in the effects of tonic Chinese herbal medicine polysaccharides on immune function and to lay the foundation for the future development of tonic Chinese herbal medicine polysaccharide products.

Effects of Reticuloendotheliosis virus on TLR-3/IFN-Β pathway in specific pathogen-free chickens

Birds infected by Reticuloendotheliosis virus (REV) are vulnerable to other microorganisms. This immunosuppression is related to the immune organs (thymus, bursa of Fabricius, and spleen) damaged by REV. The regulation of IFN-β greatly depends on pattern recognition receptor TLR-3 and nuclear factors IRF-7, NF-κB. To address if and how the TLR-3/IFN-β pathway is disturbed by REV, 60 one-day-old specific-pathogen-free chickens were intraperitoneally injected with RE virus dilution (n = 30) or stroke-physiological saline solution (n = 30). At 1, 3, 7, 21, and 28 days post-infection, after collecting thymuses, bursas, and spleens, we monitor the kinetics of TLR-3, IFN-β, NF-κB p65, and IRF-7 at transcriptional and translational levels using qPCR, Western blotting, and ELISA separately. As a result, compared with control chickens, the mRNA levels of TLR-3, IRF-7, and NF-κB p65 showed increasingly differences in the early period of REV infection. Synchronal changes occurred at translation levels. In the latter infection period, a decrease of NF-κB p65 was contemporaneous with a fall in IFN-β at both transcriptional and translational levels in the thymuses and bursas. These data suggest that the changes of IFN-β content are closely related to NF-κB p65 when REV invades chicken central immune organs. That reveals new insights into the immunosuppression mechanism of REV in avian.

Lactobacilli and bifidobacteria derived from infant intestines may activate macrophages and lead to different IL-10 secretion

In this study, three strains of lactobacilli and bifidobacteria originally isolated from healthy infants, were tested for their abilities to activate RAW264.7 cells. Gene expression and cytokine production of interleukin-10 (IL-10) of RAW264.7 cells were evaluated. The activation of extracellular regulated protein kinases 1/2 (ERK1/2), p38, and nuclear factor-κB (NK-κB) were also assessed. These results suggest lactobacilli and bifidobacteria in infants may promote production of IL-10 in macrophages, conferring a protective effect in hosts suffering from inflammation. Dimerization of TLR2 and MyD88 and subsequent phosphorylation of the key downstream signaling molecules, such as MAPKs and NK-κB, may be one of the key underlying mechanisms of activation of macrophages by these microbes. Bifidobacteria and lactobacilli induced macrophages to secrete IL-10 in a different manner, which may relate to their abilities to activate key signaling pathways mediated by TLR2 and MyD88.

In Ovo Delivered Toll-Like Receptor 7 Ligand, Resiquimod Enhances Host Responses against Infectious Bronchitis Corona Virus (IBV) Infection

Toll-like receptor (TLR) 7 ligand, resiquimod, has been studied as an adjuvant and antiviral agent against several pathogens in chicken. Yet, the effectiveness of resiquimod against infectious bronchitis virus (IBV) infection has not been evaluated. In this study, we investigated the effectiveness of resiquimod delivered pre-hatch (in ovo) against IBV infection post-hatch identifying key mechanisms involved in resiquimod driven immune activation. First, we found an upregulation of interleukin (IL)-1β and interferon (IFN)-γ mRNA levels and considerable expansions of macrophage and cluster of differentiation (CD) 8α+ T cell populations in lungs of chicken as early as day one post-hatch, following pre-hatch delivery of resiquimod. Second, we observed that resiquimod was able to act as an adjuvant when resiquimod was delivered pre-hatch along with an inactivated IBV vaccine. Finally, when the resiquimod pretreated one-day-old chickens were infected with IBV, reduction in viral shedding via oral and fecal routes was observed at 3 days post- infection. Overall, this study shows that the pre-hatch delivered resiquimod increases cell-mediated immune responses in lungs with an advantage of reduction in IBV shedding.

Antiviral responses against chicken respiratory infections: Focus on avian influenza virus and infectious bronchitis virus

Some of the respiratory viral infections in chickens pose a significant threat to the poultry industry and public health. In response to viral infections, host innate responses provide the first line of defense against viruses, which often act even before the establishment of the infection. Host cells sense the presence of viral components through germinal encoded pattern recognition receptors (PRRs). The engagement of PRRs with pathogen-associated molecular patterns leads to the induction of pro-inflammatory and interferon productions. Induced antiviral responses play a critical role in the outcome of the infections. In order to improve current strategies for control of viral infections or to advance new strategies aimed against viral infections, a deep understanding of host-virus interaction and induction of antiviral responses is required. In this review, we summarized recent progress in understanding innate antiviral responses in chickens with a focus on the avian influenza virus and infectious bronchitis virus.

Analysis of the Progeny of Sibling Matings Reveals Regulatory Variation Impacting the Transcriptome of Immune Cells in Commercial Chickens

There is increasing recognition that the underlying genetic variation contributing to complex traits influences transcriptional regulation and can be detected at a population level as expression quantitative trait loci. At the level of an individual, allelic variation in transcriptional regulation of individual genes can be detected by measuring allele-specific expression in RNAseq data. We reasoned that extreme variants in gene expression could be identified by analysis of inbred progeny with shared grandparents. Commercial chickens have been intensively selected for production traits. Selection is associated with large blocks of linkage disequilibrium with considerable potential for co-selection of closely linked "hitch-hiker alleles" affecting traits unrelated to the feature being selected, such as immune function, with potential impact on the productivity and welfare of the animals. To test this hypothesis that there is extreme allelic variation in immune-associated genes we sequenced a founder population of commercial broiler and layer birds. These birds clearly segregated genetically based upon breed type. Each genome contained numerous candidate null mutations, protein-coding variants predicted to be deleterious and extensive non-coding polymorphism. We mated selected broiler-layer pairs then generated cohorts of F2 birds by sibling mating of the F1 generation. Despite the predicted prevalence of deleterious coding variation in the genomic sequence of the founders, clear detrimental impacts of inbreeding on survival and post-hatch development were detected in only one F2 sibship of 15. There was no effect on circulating leukocyte populations in hatchlings. In selected F2 sibships we performed RNAseq analysis of the spleen and isolated bone marrow-derived macrophages (with and without lipopolysaccharide stimulation). The results confirm the predicted emergence of very large differences in expression of individual genes and sets of genes. Network analysis of the results identified clusters of co-expressed genes that vary between individuals and suggested the existence of trans-acting variation in the expression in macrophages of the interferon response factor family that distinguishes the parental broiler and layer birds and influences the global response to lipopolysaccharide. This study shows that the impact of inbreeding on immune cell gene expression can be substantial at the transcriptional level, and potentially opens a route to accelerate selection using specific alleles known to be associated with desirable expression levels.