Toll-like receptors gene expression in the gastrointestinal tract of Salmonella serovar Pullorum-infected broiler chicken

Expression of Toll-like receptors and host defence peptides in the cecum of chicken challenged with Eimeria tenella

Chicken coccidiosis, caused by Eimeria protozoa, affects poultry farming. Toll-like receptors (TLRs) and host defence peptides (HDPs) help host innate immune responses to eliminate invading pathogens, but their roles in Eimeria tenella infection remain poorly understood. Herein, 14-day-old chickens were treated orally with 50,000 E. tenella oocysts and the cecum was dissected at different timepoints. mRNA expression of 10 chicken TLRs (chTLRs) and five HDPs was measured by quantitative real-time PCR. chTLR7 and chTLR15 were upregulated significantly at 3 h post-infection while other chTLRs were downregulated (p < .05). chTLR1a, chTLR1b, chTLR2b and chTLR4 peaked at 36 h post-infection, chTLR3, chTLR5 and chTLR15 peaked at 72 h post-infection and chTLR21 expression was highest among chTLRs, peaking at 48 h post-infection (p < 0.05). For HDPs, cathelicidin (CATH) 1 to 3 and B1 peaked at 48 h post-infection, liver-expressed antimicrobial peptide 2 peaked at 96 h post-infection, and CATH 2 expression was highest among HDPs. CATH2 and CATH3 were markedly upregulated at 3 h post-infection (p < .05). The results provide insight into innate immune molecules during E. tenella infection in chicken, and indicate that innate immune responses may mediate resistance to chicken coccidiosis.

Quercetin Ameliorates Lipopolysaccharide-Induced Duodenal Inflammation through Modulating Autophagy, Programmed Cell Death and Intestinal Mucosal Barrier Function in Chicken Embryos

Diarrhea has been a global health problem for centuries, and the treatment has become increasingly difficult duo to the antibiotics overuse and resistance. Quercetin is a common flavonoid of extracts of vegetables, fruits, and traditional Chinese herbs, however, the mechanism of quercetin alleviating LPS-induced duodenal inflammation remains elusive. Specific pathogen-free chicken embryos (n = 120) were allocated to groups including control, PBS with or without alcohol, LPS (125 ng/egg) with or without quercetin (10, 20, or 40 nmol/egg, respectively), and quercetin groups (10, 20, or 40 nmol/egg). Fifteen day-old embryonated eggs were inoculated with abovementioned solutions via the allantoic cavity. At embryonic day 19, the duodena of the embryos were collected for histopathological examination, RNA extraction and real-time polymerase chain reaction, immunohistochemical investigations, and Western blotting. The results demonstrated quercetin enhanced the inflammatory cell infiltration in the Peyer's patch of the intestinal mucosa after LPS induction. The LPS-induced expressions of these inflammation-related factors (TLR4, IL-1β, MMP3, MMP9, NFKB1, IFNγ, IL-8, IL-6) were completely blocked by quercetin. Quercetin also decreased the protein expression of TLR4, IL-1β, MMP3, and MMP9 after LPS induction. Quercetin could down-regulate autophagy gene expression (ATG5, LC3-1, LC3-2, and LKB1), and decreased the protein expression of ATG5, and LC3-1/LC3-2 after LPS induction. Quercetin treatment prevented LPS-induced increases of the gene expressions of programmed cell death factors (TNFα, Fas, CASP1, CASP3, CASP12, Drp1, and RIPK1); meanwhile, quercetin decreased the protein expression of CASP1 and CASP3 after LPS challenge. LPS reduced the gene expression of mucin 2, but upregulated the mRNA and protein expression of claudin 1, occludin, and ZO-1, and this was balanced by quercetin. This evidence suggests that quercetin can alleviate duodenal inflammation induced by LPS through modulating autophagy, programmed cell death, intestinal barrier function.

Salmonella infection may alter the expression of toll like receptor 4 and immune related cells in chicken bursa of Fabricius

Toll like receptor 4 (TLR4), eosinophils and mast cells play significant role in host immunity during several pathogenic infections. However in vivo tissue expression of TLR4 and distribution pattern of eosinophils and mast cells in chicken bursa of Fabricius (BF) during Salmonella enterica serovar Typhimurium (STm) infection is poorly studied. Therefore, herein, following immunostaining, we found localization of TLR4 in follicular cortex and medulla and its expression was statistical increased after 36 h and 72 h of STm stimulation. Chromotrope 2R staining revealed that eosinophils were mostly distributed in follicular cortex, inter-follicular spaces and in or around blood vessels and their number in BF were statistical increased after 72 h of STm stimulation. The presence of eosinophils was confirmed using immunostaining with anti-rabbit eosinophil cationic protein antibody. Toluidine blue stained mast cells were mostly distributed in connective tissues between inter-follicular spaces while some were also present in follicular cortex of BF. However, STm stimulation illustrated non-significant effect on the number of mast cells or their de-granulation, instead their number were gradually decreased in BF with advancement in age of chickens. Hence, this study provided novel information about in vivo tissue distribution of TLR4, eosinophils and mast cells in BF during STm infection.

Immunomodulatory effects of phytogenics in chickens and pigs - A review

Environmental stressors like pathogens and toxins may depress the animal immune system through invasion of the gastrointestinal tract (GIT) tract, where they may impair performance and production, as well as lead to increased mortality rates. Therefore, protection of the GIT tract and improving animal health are top priorities in animal production. Being natural-sourced materials, phytochemicals are potential feed additives possessing multiple functions, including: anti-inflammatory, anti-fungal, anti-viral and antioxidative properties. This paper focuses on immunity-related physiological parameters regulated by phytochemicals, such as carvacrol, cinnamaldehyde, curcumin, and thymol; many studies have proven that these phytochemicals can improve animal performance and production. On the molecular level, the impact of inflammatory gene expression on underlying mechanisms was also examined, as were the effects of environmental stimuli and phytochemicals in initiating nuclear factor kappa B and mitogen-activated protein kinases signaling pathways and improving health conditions.

Genetic differences in ChTLR15 gene polymorphism and expression involved in Salmonella enterica natural and artificial infection respectively, of Chinese native chicken breeds, with a focus on sexual dimorphism

Chicken Toll-like receptor 15 (ChTLR15) has been shown to participate in immune activation in response to various pathogens and in the innate defence against infection. Two genetically distinct Chinese breeds of chicken (Qinyuan Partridge and Baier breeds) were used to study the correlation between ChTLR15 single nucleotide polymorphisms and the natural infection status of salmonella in hens, and also to examine genetic and sex-specific effects on ChTLR15 mRNA expression in heterophils and spleen during acute infection with Salmonella enterica serovar Enteritidis (SE) from 1 to 10 days after experimental infection. Three single-nucleotide polymorphisms (G168A, C726T and A1166G) in a single exon of ChTLR15 were identified in the two breeds, but only C726T showed a significant association with salmonella infection. Compared with layer-type Baier chicks, meat-type Qingyuan chicks showed a higher tolerance for capture stress and (SE) infection, as measured, respectively, by the modified body weight of chicks in the control group and in the infection group. Meanwhile, ChTLR15 down-regulation in heterophils and up-regulation in spleen were involved in the response to pathogenic SE colonization during the acute infection period. These significant genetic effects in females led to greater differences in both innate and adaptive immune responses than those exhibited in males. These results suggest that genetics, time and gender play important roles in the modulation of ChTLR15 mRNA level elicited by the SE-mediated immune response differentially in the two genetically distinct breeds, with a focus on sexual dimorphism.

Inductive expression of the NOD1 signalling pathway in chickens infected with Salmonella pullorum

1. The aim of this study was to describe the role of Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) receptor signalling in chicken. 2. Tissue-specific expression analysis of NOD1, receptor-interacting serine-threonine kinase 2 (RIPK2), nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase 11 (MAPK11 or p38) by quantitative real-time PCR (qRT-PCR) revealed their wide distribution in various organs and tissues. 3. Salmonella pullorum infection activated NOD1 receptor signalling in vivo and in vitro, resulting in significant induction of downstream signalling molecules RIPK2, NF-κB/p65, MAPK11/p38 and the effector molecules IL-1b and IL-8. 4. Activation of NOD1 by its agonist bacterial γ-D-glutamyl-meso-diaminopimelic acid (iE-DAP) in HD11 cells induced the adapter molecular RIPK2 and activated the NF-κB/p65 and MAPK11/p38 pathways, resulting in an increase in IL-8 but not IL-1β. Additionally, inhibition of NOD1 using NOD1-shRNA resulted in downregulation of RIPK2, MAPK11 and IL-8, while NF-κB/p65 and IL-1β were unaltered. 5. These results highlight the important role of NOD1 receptors in eliciting the innate immune response following pathogenic invasion in chicken.

RNA-seq Profiles of Immune Related Genes in the Spleen of Necrotic Enteritis-afflicted Chicken Lines

The study aimed to compare the necrotic enteritis (NE)-induced transcriptome differences between the spleens of Marek’s disease resistant chicken line 6.3 and susceptible line 7.2 co-infected with Eimeria maxima/Clostridium perfringens using RNA-Seq. Total RNA from the spleens of two chicken lines were used to make libraries, generating 42,736,296 and 42,617,720 usable reads, which were assembled into groups of 29,897 and 29,833 mRNA genes, respectively. The transcriptome changes were investigated using the differentially expressed genes (DEGs) package, which indicated 3,255, 2,468 and 2,234 DEGs of line 6.3, line 7.2, and comparison between two lines, respectively (fold change ≥2, p<0.01). The transcription levels of 14 genes identified were further examined using qRT-PCR. The results of qRT-PCR were consistent with the RNA-seq data. All of the DEGs were analysed using gene ontology terms, the Kyoto Encyclopedia of Genes and Genomes (KEGG) database and the DEGs in each term were found to be more highly expressed in line 6.3 than in line 7.2. RNA-seq analysis indicated 139 immune related genes, 44 CD molecular genes and 150 cytokines genes which were differentially expressed among chicken lines 6.3 and 7.2 (fold change ≥2, p<0.01). Novel mRNA analysis indicated 15,518 novel genes, for which the expression was shown to be higher in line 6.3 than in line 7.2 including some immune-related targets. These findings will help to understand host-pathogen interaction in the spleen and elucidate the mechanism of host genetic control of NE, and provide basis for future studies that can lead to the development of marker-based selection of highly disease-resistant chickens.