Cytokine expression in chicken peripheral blood mononuclear cells after in vitro exposure to Salmonella enterica serovar Enteritidis

Effects of turmeric, ginger, cinnamon, and garlic essential oils on HSP70, NFκB, oxidative DNA damage, inflammatory cytokines, and oxidative markers in broiler chickens

In recent years, the use of natural bioactive compounds derived from spices has garnered significant interest in poultry production due to their potential to modulate immune responses and oxidative stress. An investigation into the roles of spices essential oils (EO) on inflammatory cytokines, HSP70 and oxidative markers of broiler chickens was conducted in this study. Four spices consisting of garlic, ginger, turmeric, and cinnamon were processed to obtain their respective EO. Two hundred 1-d-old arbo acre broilers were allotted to 5 treatments consisting of B1 (control), B2 (garlic EO), B3 (ginger EO), B4 (Turmeric EO), and B5 (cinnamon EO), with EOs administered to drinking water at 30% (v/v) in a 49-d trial. Blood was sampled for assessment of hematological parameters, and serum obtained were assayed for inflammatory cytokines, antioxidant activities, nuclear factor kappa B (NFκB), 8-hydroxydeoxyguanosine (8-OHdG), and heat shock protein 70 (HSP70) levels using standard procedures. Results obtained revealed that cinnamon EO enhanced erythrocytic indices, leukocyte profile, catalase, glutathione peroxidase and interleukin 10, lowers interleukin 1 beta (IL-1β) and interferon gamma (IFN-γ), enhanced HSP70 and higher 8-OHdG levels in chicken. Garlic EO enhanced monocytes and superoxide dismutase, while reduced IFN-γ and HSP70, but increased IL-1β and tumor necrosis factor alpha (TNF-α) NFκB in broiler chickens. Ginger EO also enhanced erythrocytic indices, total antioxidant activity, lowered IFN-γ and lipid peroxidation, while turmeric EO enhanced total antioxidant activity, catalase and lowered IFN-γ and increased 8ohdg in broiler chickens. In conclusion, this study revealed that ginger and turmeric EO were more beneficial in preventing oxidative DNA damage, cinnamon EO enhanced serum oxidative status and lowered pro-inflammatory cytokines, while garlic EO reduced HSP70 in broiler chickens.

Differential immunological response detected in mRNA expression profiles among diverse chicken lines in response to Salmonella challenge

Salmonella enterica serovar Enteritidis is a bacterial pathogen that contributes to poultry production losses and human foodborne illness. The bacterium elicits a broad immune response involving both the innate and adaptive components of the immune system. Coordination of the immune response is largely directed by cytokines. The objective of the current study was to characterize the expression of a select set of cytokines and regulatory immune genes in three genetically diverse chicken lines after infection with S. Enteritidis. Leghorn, Fayoumi and broiler day-old chicks were orally infected with pathogenic S. Enteritidis or culture medium. At 2 and 18 h postinfection, spleens and ceca were collected and mRNA expression levels for 7 genes (GM-CSF, IL2, IL15, TGF-β1, SOCS3, P20K, and MHC class IIβ) were evaluated by real-time quantitative PCR. Genetic line had a significant effect on mRNA expression levels of IL15, TGF-β1, SOCS3 and P20K in the spleen and on P20K and MHC class IIβ in the cecum. Comparing challenged vs. unchallenged birds, the expression of SOCS3 and P20K mRNA were significantly higher in the spleen and cecum, while MHC class IIβ mRNA was significantly lower in spleen. Combining the current RNA expression results with those of previously reported studies on the same samples reveals distinct RNA expression profiles among the three genetic chicken lines and the 2 tissues. This study illustrates that these diverse genetic lines have distinctively different immune response to S. Enteritidis challenge within the spleen and the cecum.

Chicken Immune Cell Assay to Model Adaptive Immune Responses In Vitro

Simple Summary

Knowledge about the modes of action of immunomodulating compounds such as pathogens, drugs, or feed additives, e.g., probiotics, will allow the development of targeted nutrition strategies, prevent infectious diseases and the usage of antimicrobials, and promote the health of animals. To investigate the mechanisms of action of immunomodulating compounds, controlled in vitro systems using freshly isolated immune cells from blood represent a promising alternative to animal experiments. Immune cell isolation from the blood of chickens is a complex and difficult process since the immune cell fractions are significantly contaminated with red blood cells and platelets. To our knowledge, a robust protocol for immune cell isolation from chicken blood and the subsequent cultivation of immune cells is not available. Here, we established a protocol for blood sampling and immune cell isolation and cultivation from chicken blood, which could be applied for the investigation of direct effects of immunomodulating compounds. This protocol, combining different techniques of immune cell isolation, cultivation, and differentiation of distinct immune cell populations, will serve as a potential alternative to animal testing in vivo. By gaining knowledge about the mechanisms of action of immunomodulating compounds, this in vitro model will contribute to promote health and welfare in chicken farming.

Abstract

Knowledge about the modes of action of immunomodulating compounds such as pathogens, drugs, or feed additives, e.g., probiotics, gained through controlled but animal-related in vitro systems using primary cultured peripheral blood mononuclear cells (PBMCs) will allow the development of targeted nutrition strategies. Moreover, it could contribute to the prevention of infectious diseases and the usage of antimicrobials, and further promote the health of the animals. However, to our knowledge, a protocol for the isolation of PBMCs with reduced thrombocyte count from chicken blood and subsequent cell culture over several days to assess the effects of immunomodulating compounds is not available. Therefore, we established an optimized protocol for blood sampling and immune cell isolation, culture, and phenotyping for chicken PBMCs. For blood sampling commercial Na–citrate tubes revealed the highest count of vital cells compared to commercial Li–heparin (p < 0.01) and K3EDTA (p < 0.05) tubes. Using combined dextran and ficoll density gradient separation, the thrombocyte count was significantly reduced (p < 0.01) compared to slow-speed centrifugation with subsequent ficoll. For cell culture, the supplementation of RPMI-1640 medium with 10% chicken serum resulted in the lowest relative cell count of thrombocytes compared to fetal calf serum (FCS) (p < 0.05). To validate the ability of the cell culture system to respond to stimuli, concanavalin A (conA) was used as a positive control. The optimized protocol allows the isolation and cultivation of vital PBMCs with reduced thrombocyte count from chicken blood for subsequent investigation of the modes of action of immunomodulating compounds.

Immunization of chicken with flagellin adjuvanted Salmonella enteritidis bacterial ghosts confers complete protection against chicken salmonellosis

The present study describes the generation of Salmonella enteritidis (SE) ghosts with a surface decorated Salmonella Typhimurium (ST) flagellin (FliC) antigen for immune enhancement and strain-specific protection. The ghosts were generated by biological means using pJHL184::fliC temperature inducible plasmid where the lysis occurs by phage PhiX174 lysis gene E expression. Being an inactivated strain, no environmental contamination was observed by fecal shedding upon inoculation into the chicken. To test the protective immune responses, ghost vaccination was conducted via the intramuscular route using chicken as the model organism. The development of antigen-specific humoral, cell-mediated, and protective immune responses was assessed. Compared to vector alone and phosphate-buffered saline (PBS) control groups, pJHL184::fliC ghost could generate significantly high antigen-specific IgY and cell-mediated immune (CMI) responses measured by a peripheral blood mononuclear cell proliferation, flow cytometer, and cytokine responses elicited by stimulated splenic T-cells (P < 0.05). The adjuvant effect induced by FliC was demonstrated by elicitation of Toll-like receptor 5 (TLR5). To test the protection efficacy, chickens were challenged with both SE and ST wild type (WT) strains, and the protection efficacy was assessed by determining the presence of challenging strains in the spleen and liver, and by assessing the histopathological alterations. Complete clearance of the challenged strain and least inflammatory signs were evident in the SE ghosts vaccinated group compared to the vector and PBS control. The elimination of both SE and ST in chicken organs ensures the intramuscular immunization of the present SE ghost vaccine can reduce SE and ST contamination levels in chicken that can be beneficial to prevent enteric infections in humans.

TLR-Mediated Cytokine Gene Expression in Chicken Peripheral Blood Mononuclear Cells as a Measure to Characterize Immunobiotics

Immunobiotics are probiotics that promote intestinal health by modulating immune responses. Immunobiotics are recognized by Toll-like receptors (TLRs) and activate cytokine gene expression. This study aimed to characterize cytokine gene expression in the chicken peripheral blood mononuclear cells (PBMC) stimulated with purified TLR ligands and live probiotics. PBMC were isolated from the whole blood. PBMC were stimulated with: lipopolysaccharide (LPS), CpG ODN, Pam3CSK4, Zymosan, galactooligosaccharides (GOS), Lactococcuslactis subsp. cremoris (L. lactis), and Saccharomyces cerevisiae at 42.5 °C and 5% CO₂ for 3 h, 6 h, and 9 h. After each time-point, PBMC were harvested for RNA isolation. Relative gene expression was analyzed with RT-qPCR for cytokine genes (IL-1β, IL-2, IL-3, IL-4, IL-6, IL-8, IL-10, IL-12p40, and IFN-ɣ) and reference genes (ACTB and G6PDH). Genes were clustered into pro-inflammatory genes, Th1/Th2 genes, and Th1-regulators. The gene expression differed between treatments in IL1-β, IL-6, IL-8, IL-10, and IL-12p40 (p < 0.001). The genes IL-1β, IL-6, and IL-8 had the highest fold change of mRNA expression at 3 h in response to TLR ligands. L. lactis up-regulated the pro-inflammatory genes at the 6 h time-point. L. lactis did not activate the anti-inflammatory IL-10 gene, but activated IL-12p40 at 6 h. Hereby, L. lactis was proven to exert immunostimulatory properties in PBMC.

Effects of Saccharomyces cerevisiae and phytase co-fermentation of wheat bran on growth, antioxidation, immunity and intestinal morphology in broilers

OBJECTIVE

The aim of this study was to investigate the effects of different amounts of wheat bran (WB) inclusion and postbiotics form by Saccharomyces cerevisiae and phytase cofermented wheat bran (FWB) on the growth performance and health status of broilers.

METHODS

Study randomly allocated a total of 300 male broilers to a control and 4 treatment groups (5% WB, 5% FWB, 10% WB, and 10% FWB inclusion, respectively) with each pen having 20 broilers and 3 pens per treatment.

RESULTS

The WB does not contain enzymes, but there are 152.8, 549.2, 289.5, and 147.1 U/g dry matter xylanase, protease, cellulase and β-glucanase in FWB, respectively. Furthermore, FWB can decrease nitric oxide release of lipopolysaccharide stimulated chicken peripheral blood mononuclear cells by about two times. Results show that 10% FWB inclusion had significantly the highest weight gain (WG) at 1 to 21 d; 5% FWB had the lowest feed conversion rate at 22 to 35 d; 10% WB and 10% FWB inclusion have the highest villus height and Lactobacillus spp. number in caecum; and both 5% and 10% FWB can increase ash content in femurs. Compared to control group, all treatments increase mucin 2, and tight junction (TJ), such as occludin, claudin-1, zonula occludens-1, and mRNA expression in ileum by at least 5 folds. In chicken peripheral blood mononuclear cells, nicotinamide adenine dinucleotide phosphate-oxidase-1 mRNA expression decreases from 2 to 5 times, and glutamate-cysteine ligase catalytic subunit mRNA expression also increases in all treatment groups compared to control group. The mRNA expression of pro-inflammatory cytokines, including interleukin-6 (IL-6), nuclear factor-κB, and IL-1β, decreases in 5% and 10% FWB groups compared to control group.

CONCLUSION

To summarize, both WB and FWB inclusion in broilers diets increase TJ mRNA expression and anti-oxidation and anti-inflammation, but up to 10% FWB groups have better WG in different stages of broiler development.

The correlated expression of immune and energy metabolism related genes in the response to Salmonella enterica serovar Enteritidis inoculation in chicken

Background

Salmonella enterica serovar Enteritidis (SE) is one of the food-borne pathogenic bacteria, which affects poultry production and poses severe threat to human health. The correlation of immune system and metabolism in chicken after SE inoculation is important but not clear. In the current study, we identified the expression of immune and energy metabolism related genes using quantitative PCR to evaluate the correlation between immune system and energy metabolism against SE inoculation in Jining Bairi chicken.

Results

ATP5G1, ATP5G3 and ND2 were significantly up-regulated at 1 dpi (day post inoculation), and ATP5E, ATP5G1, ATP5G3 were significantly down-regulated at 7 dpi (P < 0.05). IL-8 and IL-1β were significantly down-regulated at 1 dpi, IL-8 and IL-18 were significantly down-regulated at 3 dpi, IL-8 and BCL10 were significantly up-regulated at 7 dpi (P < 0.05).

Conclusions

These findings indicate that the correlation between immune and energy metabolism related genes gradually change with time points post SE inoculation, from one homeostasis to an opposite homeostasis with 3 dpi as a turning point. These results will pave the foundation for the relationship between immune system and energy metabolism in the response to SE inoculation in chicken.

Effect of calcium stearoyl-2 lactylate and lipase supplementation on growth performance, gut health, and nutrient digestibility of broiler chickens

Objective

To evaluate calcium stearoyl-2 lactylate (CSL) performance as an exogenous emulsifier together with lipase for broiler diets.

Methods

In total, 252 one-day-old Ross 308 broiler chickens were allocated in a completely randomized design to give 6 replications per treatment with 7 birds in each cage. There were six dietary treatments representing a 2×3 factorial arrangement consisted of two energy levels (standard energy [positive control, PC] and −100 kcal/kg of the requirement level [negative control, NC]) and three dietary treatments (without additives [CON], CON+CSL [CSL], and CON+CSL+lipase [CSL-Lipase]). Corn and soybean meal-based experimental diets containing vegetable oil were formulated. Growth performance, blood parameters, visceral organ weights, ileal morphology, nutrient digestibility, and cytokine gene expression were measured.

Results

Birds fed a diet including CSL increased (p<0.05) lipase level in blood compared to birds fed a diet including CSL-Lipase on day 21. Similarly, higher (p<0.05) liver weight was observed in birds fed a diet including either CSL or CSL-Lipase on day 21. Birds fed NC diet with CSL improved (p<0.05) nutrient digestibility compared to the NC diet on day 21. However, birds fed a diet supplemented with CSL or CSL-Lipase did not affect (p>0.05) the weight gain, feed efficiency, ileal morphology, and cytokine concentrations during the experiment period, regardless of dietary energy levels.

Conclusion

Our results indicated that CSL has a role in improving nutrient digestibility in young birds when supplemented to a corn-soybean meal based broiler diet.

Characterisation and functional analysis of canine TLR5

In this study, we characterised the single exon TLR5 gene of the Chinese rural dog. Sequence analysis revealed a 2577 nucleotide-long open reading frame of canine TLR5, encoding an 858 amino acid-long protein. The putative amino acid sequence of canine TLR5 consisted of a signal peptide sequence, 15 LRR domains, a LRR C-terminal domain, a transmembrane domain and an intracellular Toll-IL-1 receptor domain. The amino acid sequence of the canine TLR5 protein shared 95.4% identity with vulpine, 72.2% with feline and 64.7% with human TLR5. Plasmids expressing canine TLR5 and NF-κB-luciferase were constructed and transfected into HEK293T cells. Expression was confirmed by indirect immunofluorescence assay. These HEK293T cells transfected with the canine TLR5- and NF-κB-luciferase plasmids significantly responded to flagellin from Salmonella enteritidis serovar Typhimurium, indicating that it is a functional TLR5 homolog. In response to stimulation with Salmonella enteritidis, the level of TLR5 mRNA significantly increased over the control in PBMCs at 4 h. The levels of IL-8, IL-6 and IL-1β also increased after exposure. The highest levels of TLR5, IL-8 and IL-1β expression were detected at 8, 4 and 12 h after stimulation, respectively. These results imply that the expression of canine TLR5 may participate in the immune response against bacterial pathogens.

Evaluation of the Combined Use of Saccharomyces Cerevisiae and Aspergillus Oryzae with Phytase Fermentation Products on Growth, Inflammatory, and Intestinal Morphology in Broilers

Saccharomyces cerevisiae and Aspergillus oryzae are both ancient probiotic species traditionally used as microbes for brewing beer and soy sauce, respectively. This study investigated the effect of adding these two probiotics with phytase fermentation products to the broilers diet. Fermented products possess protease and cellulase, and the activities were 777.1 and 189.5 U/g dry matter (DM) on S. cerevisiae fermented products (SCFP) and 190 and 213.4 U/g DM on A. oryzae fermented products (AOFP), respectively. Liposaccharides stimulated PBMCs to produce nitric oxide to 120 μmol. Both SCFP and AOFP reduced lipopolysaccharides stimulated peripheral blood mononuclear cells (PBMCs) nitric oxide release to 40 and 60 μmol, respectively. Nevertheless, in an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, SCFP and AOFP also increased the survival rate of lipopolysaccharides stimulated PBMCs by almost two-fold compared to the negative control. A total of 240 broilers were divided into four groups as Control, SCFP 0.1% (SCFP), SCFP 0.05% + AOFP 0.05% (SAFP), and AOFP 0.1% (AOFP) groups, respectively. Each group had 20 broilers, and three replicate pens. The results showed that the addition of SCFP, SAFP, and AOFP groups did not affect the growth performances, but increased the jejunum value of villus height and villus: crypt ratio on SAFP and AOFP groups compared to the control and SCFP groups. Furthermore, adding SCFP, SAFP, and AOFP significantly reduced the number of Clostridium perfringens in ileum chyme. SCFP, SAFP, and AOFP significantly reduced the amount of interleukin-1β, inducible nitric oxide synthases, interferon-γ, and nuclear factor kappa B mRNA expression in PBMCs, especially in the AOFP group. In summary, all the SCFP, SAFP, and AOFP groups can be suggested as a functional feed additive since they enhanced villus: crypt ratio and decreased inflammation-related mRNA expression, especially for AOFP group in broilers.

Infectious bursal disease virus inoculation infection modifies Campylobacter jejuni-host interaction in broilers

BACKGROUND

Campylobacter jejuni is considered as a chicken commensal. The gut microbiota and the immune status of the host may affect its colonization. Infectious bursal disease virus (IBDV) is an immunosuppressive virus of chickens, which allows secondary pathogens to invade or exacerbates their pathogenesis. To investigate the effect of IBDV-induced immunosuppression on the pathogenesis of C. jejuni, broiler chickens were inoculated with a very virulent (vv) strain of IBDV at 14 days post hatch followed by C. jejuni inoculation at 7 (Experiment A) or 9 (Experiment B) days post virus (IBDV) inoculation.

RESULTS

vvIBDV-infection led to a depression in caecal lamina propria B lymphocytes and the anti-C. jejuni-antibody response starting at 14 days post C. jejuni inoculation (pbi). The C. jejuni-colonization pattern was comparable between mono-inoculated groups of both experiments, but it varied for vvIBDV + C. jejuni co-inoculated groups. In Experiment A significant higher numbers of colony forming units (CFU) of C. jejuni were detected in the caecum of co-inoculated birds compared to C. jejuni-mono-inoculated birds in the early phase after C. jejuni-inoculation. In Experiment B the clearance phase was affected in the co-inoculated group with significantly higher CFU at 21 days pbi compared to the mono-inoculated group (P < 0.05). No major differences were seen in numbers local lamina propria T lymphocyte populations between C. jejuni-inoculated groups with or without vvIBDV-infection. Interestingly, both pathogens affected the microbiota composition. The consequences of these microflora changes for the host have to be elucidated further.

CONCLUSION

Our data suggests that the timing between viral and bacterial infection might affect the outcome of C. jejuni colonization differently. Our results confirm previous studies that anti-Campylobacter-antibodies may specifically be important for the clearance phase of the bacteria. Therefore, as vvIBDV is widely distributed in the field, it may have a significant impact on the colonization and shedding rate of C. jejuni in commercial poultry flocks. Subsequently, successful IBDV-control strategies may indirectly also benefit the gut-health of chickens.

Generation and evaluation of a recombinant Newcastle disease virus strain R2B with an altered fusion protein cleavage site as a vaccine candidate

Newcastle disease (ND) is a highly contagious and fatal disease of chickens. Newcastle disease virus (NDV) strain R2B is an Indian mesogenic strain used for secondary vaccination in chickens. Mesogenic strains have increased virulence and immunogenicity but may cause disease in vaccinated birds, thus rendering them ineffective for use. In this study, we generated a recombinant NDV by changing the fusion protein cleavage site of mesogenic rNDV-R2B from a polybasic amino acid motif RRQKRF to a dibasic amino acid motif GRQGRL leading to generation of an attenuated virus, rNDV-R2B-FPCS. The modified recombinant virus had similar growth characteristics as rNDV-R2B, but was less virulent in susceptible chickens. Immunization of the recombinant attenuated virus to one week of age SPF chickens generated a protective immune response with a substantial reduction in virus shed after challenge with virulent NDV. The results of the study indicate that the modified rNDV-R2B-FPCS virus can be used for primary immunization in birds without any adverse reactions.

Dietary inclusion level effects of a phytogenic characterised by menthol and anethole on broiler growth performance, biochemical parameters including total antioxidant capacity and gene expression of immune-related biomarkers

The supplementation of a phytogenic feed additive (PFA) characterised by menthol and anethole was evaluated at three levels on broiler growth performance, nutrient digestibility, biochemical parameters, total antioxidant capacity of plasma, breast and thigh meat as well as on the relative gene expression of immune-related biomarkers. A total of 225 1-day-old male Cobb-500 were assigned into three treatments with five replicates of 15 chicks each. Wheat-soybean meal basal diets were formulated according to a three-phase (i.e. starter, grower and finisher) feeding program. Dietary treatments were: no PFA, PFA at 100 mg/kg diet and PFA at 150 mg/kg diet. Feed and water were available ad libitum. Performance parameters were monitored weekly and all other biological responses were determined at 42 days of broiler age. Increasing PFA level increased (P = 0.044) bodyweight gain at finisher period, decreased quadratically (P = 0.035) overall feed intake, and quadratically improved (P = 0.024) overall feed conversion ratio. Moreover, increasing PFA level increased plasma total antioxidant capacity linearly (P = 0.001) whereas linearly decreased (P = 0.005) triglyceride concentration. Thigh meat cholesterol decreased linearly (P = 0.016) with increasing PFA level. Expression of pro-inflammatory cytokine IL-2 in caecal tonsils increased quadratically (P = 0.046) with increasing PFA level. In conclusion, PFA inclusion at 100 mg/kg diet affected positively performance whereas a stronger improvement mainly in plasma total antioxidant capacity and triglyceride as well as in meat cholesterol was noted for the 150 mg/kg diet level. Inclusion of PFA resulted in increasing pro-inflammatory biomarker IL-2 at local caecal level.

Single nucleotide variant discovery of highly inbred Leghorn and Fayoumi chicken breeds using pooled whole genome resequencing data reveals insights into phenotype differences

Background

Analyses of sequence variants of two distinct and highly inbred chicken lines allowed characterization of genomic variation that may be associated with phenotypic differences between breeds. These lines were the Leghorn, the major contributing breed to commercial white-egg production lines, and the Fayoumi, representative of an outbred indigenous and robust breed. Unique within- and between-line genetic diversity was used to define the genetic differences of the two breeds through the use of variant discovery and functional annotation.

Results

Downstream fixation test (F_ST) analysis and subsequent gene ontology (GO) enrichment analysis elucidated major differences between the two lines. The genes with high F_ST values for both breeds were used to identify enriched gene ontology terms. Over-enriched GO annotations were uncovered for functions indicative of breed-related traits of pathogen resistance and reproductive ability for Fayoumi and Leghorn, respectively.

Conclusions

Variant analysis elucidated GO functions indicative of breed-predominant phenotypes related to genomic variation in the lines, showing a possible link between the genetic variants and breed traits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3147-7) contains supplementary material, which is available to authorized users.

Cytokine activation during embryonic development and in hen ovary and vagina during reproductive age and Salmonella infection

Salmonellosis is one of the most important zoonotic diseases and is usually associated with consumption of Salmonella Enteritidis (SE) contaminated poultry meat or eggs. Contamination with SE is usually the result of infection of the digestive tract, or reproductive organs, especially the ovary and vagina. Thus, knowledge of endogenous innate immune mechanisms operating in the ovary and vagina of hen is an emerging aspect of reproductive physiology. Cytokines are key factors for triggering the immune response and inflammation in chicken to Salmonella infection. The aim of this study was to investigate the expression profile of 11 proinflammatory cytokines in the chicken embryos during embryonic development, as well as in the hen ovary and vagina in vivo, to investigate whether sexual maturation affects their ovarian and vaginal mRNA abundance and to determine whether cytokine expression was constitutive or induced in the ovary and vagina as a response to SE infection. RT-PCR analysis revealed that several cytokines were expressed in the chicken embryos, and in the ovary and vagina of healthy birds. Expression of various cytokines during sexual maturation appeared to be developmentally regulated. In addition, a significant up-regulation of several cytokines in the ovary and vagina of sexually mature SE infected birds compared to healthy birds of the same age was observed. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the hen reproductive organs.

Transcriptional changes of cytokines in rooster testis and epididymis during sexual maturation stages and Salmonella infection

Infection of rooster testis and epididymis by pathogens can lead to impaired fertility, resulting in economic losses in the poultry industry. Antimicrobial protection of rooster reproductive organs is, therefore, an important aspect of reproductive physiology. Salmonellosis is one of the most important zoonotic diseases, caused by Salmonella bacteria including Salmonella Enteritidis (SE) and is usually the result of infection of the reproductive organs. Thus, knowledge of the endogenous innate immune mechanisms of the rooster testis and epididymis is an emerging aspect of reproductive physiology. Cytokines are key factors for stimulating the immune response and inflammation in chickens to Salmonella infection. In the present study the expression profile of 11 pro-inflammatory cytokine genes in the rooster testis and epididymis in vivo and transcriptional changes in these organs during sexual maturation and SE infection were investigated. Gene expression analysis data revealed that in both testis and epididymis nine cytokines namely the IL-1β, IL-6, IL-8, IL-10, IL-12, IL-15, IL-16, IL-17 and IL-18 genes were expressed, while no mRNA transcripts were detected in both organs for IL-2 and IL-4. Furthermore, the expression of various cytokine genes during sexual maturation appeared to be developmentally regulated, while SE infection resulted in a significant up-regulation of IL-1β, -6, -12 and -18 genes in the testis and an increase in the mRNA relative abundance of IL-1β, -6, -12, -16 and -18 in the epididymis of SE-infected sexually mature 28-week-old roosters. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the rooster reproductive tract.

Regulation of chicken immunity-related genes and host response profiles against Avibacterium paragallinarum pathogen challenge

Infectious coryza (IC) is a well-recognised and commonly encountered upper respiratory tract disease in chickens. The aim of this study was to monitor aspects of the immune response of chickens infected with Avibacterium paragallinarum. Gene expression profiling of 30 genes was carried out for 11 chicken nasal area samples belonging to four groups, including one non-infected control group. For this purpose, 30 biomarker transcripts were selected for comparative gene expression analysis and were analysed by real-time PCR using TaqMan(®) assays. The biomarkers included three reference genes. The reference genes were used to normalise the results in a relative quantification approach. The gene expression changes of the 27 biomarker transcripts (genes of interest) were quantified between all treated groups in six pair-wise comparisons. It was concluded from the data that immune response initiation is via TLR4, which leads to a Th2 dominant type response. Furthermore, TLR4 results in signalling via the MyD88-dependent pathway, resulting in early onset of NF-kβ leading to the production of inflammatory cytokines. This work provides an informative outlay of immune response initiation upon infection with this pathogen.

Protective efficacy of a DNA vaccine construct encoding the VP2 gene of infectious bursal disease and a truncated HSP70 of Mycobacterium tuberculosis in chickens

Infectious bursal disease (IBD) is an acute, infectious, immunosuppressive disease affecting young chicken worldwide. The etiological agent IBD virus (IBDV) is a double stranded RNA virus with outer capsid protein VP2 of IBDV is the major antigenic determinant capable of inducing neutralizing antibody. DNA vaccines encoding VP2 has been extensively studied achieving only partial protection. However, the efficacy of DNA vaccines against IBDV can be augmented by choosing a potential molecular adjuvant. The goal of the present study is to evaluate the immune response and protective efficacy of a DNA vaccine encoding the C-terminal domain of the heat shock protein 70 (cHSP70) of Mycobacterium tuberculosis gene genetically fused with the full length VP2 gene of IBDV (pCIVP2-cHSP70) in comparison to a 'DNA prime-protein boost' approach and a DNA vaccine encoding the VP2 gene (pCIVP2) alone. The results indicate that both pCIVP2-cHSP70 and 'DNA prime-protein boost' elicited humoral as well as cellular immune responses. Chickens in the pCIVP2-cHSP70 and 'DNA prime-protein boost' groups developed significantly higher levels of ELISA titer to IBDV antigen compared to the group immunized with pCIVP2 alone (p<0.01). However, significantly higher levels of lymphocyte proliferative response, IL-12 and IFN-γ production were found in the pCIVP2-cHSP70 group compared to 'DNA prime-protein boost' group. Additionally, chickens immunized with pCIVP2-cHSP70 and 'DNA prime-protein boost' vaccines were completely protected against the vvIBDV whereas pCIVP2 DNA vaccine alone was able to protect only 70%. These findings suggest that the truncated C-terminal HSP70 mediated DNA vaccine genetically fused with the VP2 gene construct stimulated both humoral and cell mediated immune responses and conferred complete protection against IBDV. This novel strategy is perhaps a seminal concept in utilizing HSP70 as an adjuvant molecule to elicit an immune response against IBD affecting chickens.

Alteration in lymphocytes responses, cytokine and chemokine profiles in laying hens infected with Salmonella Typhimurium

Salmonella Typhimurium has been reported to contaminate egg production across the world, but the exact nature of the immune mechanisms protective against Salmonella infection in laying hens has not been characterized at the molecular level. The experiment was conducted to determine Salmonella colonization and lymphocytes subpopulation in the ileum and spleen, and the mRNA expression of pro-inflammatory cytokines [interleukin (IL)-1β and IL-6], chemokine IL-8, and T helper (Th)1/Th2 cytokines [Interferon (IFN)-γ, IL-12 and IL-18; IL-4 and IL-10 respectively] in the cecal tonsil and spleen of Salmonella challenged hens. Forty Salmonella-free laying hens were challenged orally with Salmonella Typhimurium or phosphate-buffered saline (PBS; control). The Salmonella challenged or non-challenged hens (n=10) were sacrificed at 2 and 7 days post-infection (DPI). The lymphocyte subpopulation was determined via flow cytometric analysis in the ileum and spleen. The cecal tonsil and spleen samples were collected for mRNA expression through quantitative-RT-PCR. The Salmonella counts were higher (P<0.05) in the ileum than that in the spleen at 2 and 7DPI, and were higher (P<0.05) at 7DPI than that at 2DPI in the spleen. Salmonella challenge increased (P<0.05) ileal CD4+ and CD8α+ cells ratios at 2 and 7DPI, whereas it increased (P<0.05) splenic CD8α+ cells ratio only at 7DPI. The magnitude of increase in ileal CD8α+ cells ratio was higher (P<0.05) than that in CD4+ cells ratio. The mRNA expression of IL-1β, IL-6, IL-8, IFN-γ, IL-12 and IL-18 were significantly up-regulated in the cecal tonsil of Salmonella challenged hens, and the magnitude of increases in IL-6, IL-8 and IL-12 were significantly higher at 7DPI than that at 2DPI. However, Salmonella challenge increased (P<0.05) the mRNA expression of IL-1β, IL-10 and IL-18 at 2 and 7DPI, and IL-8 and IFN-γ mRNA only at 7DPI in the spleen. These findings demonstrated that there appeared the induction of cellular immune responses, and a Th1-cytokines reaction in the intestine and spleen of laying hens infected with Salmonella Typhimurium.

In vitro rapid clearance of infectious bursal disease virus in peripheral blood mononuclear cells of chicken lines divergent for antibody response might be related to the enhanced expression of proinflammatory cytokines

Infectious bursal disease (IBD) is an acute and highly contagious viral disease of young chickens caused by infectious bursal disease virus (IBDV). An effective way to control IBDV would be to breed chickens with a reduced susceptibility to IBDV infection. In the present work, we used chickens selected for high and low specific responses to sheep red blood cells (SRBC) (H and L, respectively) to assess the susceptibility of differential immune competent animals to IBDV infection. The peripheral blood mononuclear cells (PBMCs) of high SRBC line (HL) and low SRBC line (LL) were infected with IBDV and viral RNA loads were determined at different time post-IBDV infection. Chicken orthologues of the T helper 1 (Th1) cytokines, interferon-γ (IFN-γ) and interleukin-2 (IL-2); a Th2 cytokine, IL-10; a pro inflammatory cytokine, IL-6; the CCL chemokines, chCCLi2, chCCLi4 and chCCLi7; colony stimulating factor, GM-CSF; and a anti-inflammatory cytokine, transforming growth factor β-2 (TGFβ-2) were quantified. The expression of chCCLi2, chCCLi4 and chCCLi7 was significantly higher in L line as compared to H line. However, in H line the viral RNA loads were significantly lower than in L line. Therefore, the upregulated chemokines might be associated with the susceptibility to IBDV. The expression of IFN-γ, IL-2 and IL-6 was significantly higher in H line as compared to L line. We assume that the higher proinflammatory cytokines expression in H line might be related to the rapid clearance of virus from PBMCs. Significantly higher levels of IL-10 and TGFβ-2 mRNAs in L line might be related to the pathogenesis of IBDV. In conclusion, selection for antibody responses appears to influence the expression profiles of chemokines and cytokines against IBDV. Further, the selection for high SRBC response might improve the immuno-competence of chickens against IBDV.

A mathematical model representing cellular immune development and response to Salmonella of chicken intestinal tissue

The aim of this study was to create a dynamic mathematical model of the development of the cellular branch of the intestinal immune system of poultry during the first 42 days of life and of its response towards an oral infection with Salmonella enterica serovar Enteritidis. The system elements were grouped in five important classes consisting of intra- and extracellular S. Enteritidis bacteria, macrophages, CD4+, and CD8+ cells. Twelve model variables were described by ordinary differential equations, including 50 parameters. Parameter values were estimated from literature or from own immunohistochemistry data. The model described the immune development in non-infected birds with an average R² of 0.87. The model showed less accuracy in reproducing the immune response to S. Enteritidis infection, with an average R² of 0.51, although model response did follow observed trends in time. Evaluation of the model against independent data derived from several infection trials showed strong/significant deviations from observed values. Nevertheless, it was shown that the model could be used to simulate the effect of varying input parameters on system elements response, such as the number of immune cells at hatch. Model simulations allowed one to study the sensitivity of the model outcome for varying model inputs. The initial number of immune cells at hatch was shown to have a profound impact on the predicted development in the number of systemic S. Enteritidis bacteria after infection. The theoretical contribution of this work is the identification of responses in system elements of the developing intestinal immune system of poultry obtaining a mathematical representation which allows one to explore the relationships between these elements under contrasting environmental conditions during different stages of intestinal development.

Cloning, characterization and widespread expression analysis of testicular piRNA-like chicken RNAs

Piwi-interacting RNAs (piRNAs) are small RNAs abundant in the germline that have been implicated in germline development and maintenance of genomic integrity across several animal species including human, mouse, rat, zebrafish and drosophila. Tens of thousands of piRNAs have been discovered, yet abundant piRNAs have still not been detected in various eukaryotic organisms. This is a report on the characterization, cloning and expression profiling of piRNA-like chicken RNAs. Here, we identified 19 piRNAs, each 23-39 nucleotides long, from chicken testis using a small RNA cDNA library and T-A cloning methods. Three different pilRNAs were selected according to size, homology and secondary structure for temporal and spatial expression by Q-PCR technology in different tissues at five growth and four development stages of Chinese indigenous Rugao chickens (RG) and introduced recessive white feather chickens (RW). We found that, consistent to other organisms, pilRNA-encoding sequences within the chicken genome were asymmetrically distributed on the chromosomes while displaying a preference for intergenic regions across the genome. Interestingly, unlike miRNAs with unique stem-loop structures (mature miRNAs form stem section and the rest form loop section), distinct secondary structures of pilRNAs were predicted. In addition, chicken pilRNAs were not only abundant in the germline but also existed in somatic tissues, where, expression levels were influenced mainly by different pilRNAs, breed and gender. Taken together, our results suggest that two distinct secondary structures exist between pilRNAs and miRNAs, which may clarify the splicing and processing mechanisms of the two small RNAs are possible different. Moreover, our results suggest that pilRNAs may not only be confined to development and maintenance of the germline but may also play important roles in somatic tissues. Additionally, different pilRNAs may be involved in the unique regulatory machinery of complex biological processes.

An assessment of opportunities to dissect host genetic variation in resistance to infectious diseases in livestock

This paper reviews the evidence for host genetic variation in resistance to infectious diseases for a wide variety of diseases of economic importance in poultry, cattle, pig, sheep and Atlantic salmon. Further, it develops a method of ranking each disease in terms of its overall impact, and combines this ranking with published evidence for host genetic variation and information on the current state of genomic tools in each host species. The outcome is an overall ranking of the amenability of each disease to genomic studies that dissect host genetic variation in resistance. Six disease-based assessment criteria were defined: industry concern, economic impact, public concern, threat to food safety or zoonotic potential, impact on animal welfare and threat to international trade barriers. For each category, a subjective score was assigned to each disease according to the relative strength of evidence, impact, concern or threat posed by that particular disease, and the scores were summed across categories. Evidence for host genetic variation in resistance was determined from available published data, including breed comparison, heritability studies, quantitative trait loci (QTL) studies, evidence of candidate genes with significant effects, data on pathogen sequence and on host gene expression analyses. In total, 16 poultry diseases, 13 cattle diseases, nine pig diseases, 11 sheep diseases and three Atlantic salmon diseases were assessed. The top-ranking diseases or pathogens, i.e. those most amenable to studies dissecting host genetic variation, were Salmonella in poultry, bovine mastitis, Marek's disease and coccidiosis, both in poultry. The top-ranking diseases or pathogens in pigs, sheep and Atlantic salmon were Escherichia coli, mastitis and infectious pancreatic necrosis, respectively. These rankings summarise the current state of knowledge for each disease and broadly, although not entirely, reflect current international research efforts. They will alter as more information becomes available and as genome tools become more sophisticated for each species. It is suggested that this approach could be used to rank diseases from other perspectives as well, e.g. in terms of disease control strategies.

A new Lactobacillus plantarum strain, TN8, from the gastro intestinal tract of poultry induces high cytokine production

This study aimed to determine the probiotic potential of 100 strains of Lactic Acid Bacteria (LAB) isolated from different intestinal segments of indigenous poultry in Tunisia. The strains were submitted to a battery of standard tests and criteria commonly used for determining their probiotic properties and attributes. The findings revealed that 19 of the isolates exhibited antimicrobial activity against 4 pathogenic bacteria, and that 4 (TN1, TN8, TN7, and TN13) showed good resistance to pH 3 and 5% bovine bile. Three isolates, namely TN1, TN8, and TN13, showed sensitivity to several antibiotics and were, therefore, selected for further enzymatic activity assays. Two isolates, namely TN1 and TN8, showed high efficacy of adhesion to chicken enterocytes. The cytokines released after stimulation by the two isolates showed high anti-inflammatory profiles, with an increased rate of Interleukin-10 (IL-10) production for the TN8 strain. Showing the highest performance, TN8 was submitted to 16S rRNA gene sequencing, which revealed that the strain was of the species Lactobacillus plantarum. Overall, the findings indicate that the Lactobacilli from poultry intestine has a number of promising properties that make it candidate for application as a probiotic additive in poultry industry.

Early immune dynamics following infection with Salmonella enterica serovars Enteritidis, Infantis, Pullorum and Gallinarum: cytokine and chemokine gene expression profile and cellular changes of chicken cecal tonsils

Salmonella enterica subspecies enterica infection remains a serious problem in a wide range of animals and in man. Poultry-derived food is the main source of human infection with the non-host-adapted serovars while fowl typhoid and pullorum disease are important diseases of poultry. We have assessed cecal colonization and immune responses of newly hatched and older chickens to Salmonella serotypes Enteritidis, Infantis, Gallinarum and Pullorum. S. Enteritidis and S. Infantis colonized the ceca more efficiently than S. Gallinarum and S. Pullorum. Salmonella infection was also associated with increased staining for B-lymphocytes and macrophages in the cecal tonsils of infected birds. S. Enteritidis infection in newly hatched birds stimulated the expression of CXCLi1 and CXCLi2 chemokines in the cecal tonsils, while S. Gallinarum up-regulated the expression of LITAF. In older chickens, S. Enteritidis infection resulted in a significantly higher expression of CXCLi2, iNOS, LITAF and IL-10 while S. Pullorum appeared to down-regulate CXCLi1 expression in the cecal tonsils. Data from spleens showed either no expression or down-regulation of the tested genes.

Immune dynamics following infection of avian macrophages and epithelial cells with typhoidal and non-typhoidal Salmonella enterica serovars; bacterial invasion and persistence, nitric oxide and oxygen production, differential host gene expression, NF-κB signalling and cell cytotoxicity

Poultry-derived food is a common source of infection of human with the non-host-adapted salmonellae while fowl typhoid and pullorum disease are serious diseases in poultry. Development of novel immune-based control strategies against Salmonella infection necessitates a better understanding of the host-pathogen interactions at the cellular level. Intestinal epithelial cells are the first line of defence against enteric infections and the role of macrophages is crucial in Salmonella infection and pathogenesis. While gene expression following Salmonella infection has been investigated, a comparison between different serovars has not been, as yet, extensively studied in poultry. In this study, chicken macrophage-like cells (HD11) and chick kidney epithelial cells (CKC) were used to study and compare the immune responses and mechanisms that develop after infection with different Salmonella serotypes. Salmonella serovars Typhimurium, Enteritidis, Hadar and Infantis showed a greater level of invasion and/or uptake characters when compared with S. Pullorum or S. Gallinarum. Nitrate and reactive oxygen species were greater in Salmonella-infected HD11 cells with the expression of iNOS and nuclear factor-κB by chicken macrophages infected with both systemic and broad host range serovars. HD11 cells revealed higher mRNA gene expression for CXCLi2, IL-6 and iNOS genes in response to S. Enteritidis infection when compared to S. Pullorum-infected cells. S. Typhimurium- and S. Hadar-infected HD11 showed higher gene expression for CXCLi2 versus S. Pullorum-infected cells. Higher mRNA gene expression levels of pro-inflammatory cytokine IL-6, chemokines CXCLi1 and CXCLi2 and iNOS genes were detected in S. Typhimurium- and S. Enteritidis-infected CKC followed by S. Hadar and S. Infantis while no significant changes were observed in S. Pullorum or S. Gallinarum-infected CKC.

Analysis of immune-related gene expression in chicken peripheral blood mononuclear cells following Salmonella enterica serovar Enteritidis infection in vitro

We examined mRNA expression of eight genes, TLR4, TLR5, TLR15, interleukin (IL)-1β, IL-6, transforming growth factor-β4 (TGF-β4), CXCLi2, and a macrophage inflammatory protein (MIP) family chemokine called CCLi2, in peripheral blood mononuclear cells (PBMCs) isolated from the blood of chickens after in vitro exposure to Salmonella enterica serovar Enteritidis (SE). The chickens of four Chinese native lines, Qingjiaoma, Sanhuang, Wugu, and Xueshanma, were evaluated for mRNA expression levels at 2 and 4h post-infection using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). TLR4 and TLR15 mRNA were in particular highly expressed in PBMCs of Wugu and Xueshanma chickens exposed to SE, while TLR5 was expressed less in the Sanhuang chickens than in others. Breed effect was significant (P<0.05) for IL-1β, IL-6, CXCLi2, and CCLi2 mRNA expression, all of which were expressed to a greater extent in Wugu and Xueshanma than in the other two lines. These findings demonstrate the difference of mRNA expression profiles for innate immune molecules in PBMCs infected to SE among different lines.

Shift in chicken intestinal gene association networks after infection with Salmonella

A primary infection of Salmonella enteritidis causes a spatial-temporal dependent change in the gene expression patterns in the intestine of chickens (Gallus gallus). This is the result of a dynamic intestinal response to adapt to the altered environment and to optimize its 'health' and functionality under the new circumstances. By inferring gene association networks (GANs), the complexities of and changes in biological networks can be uncovered. Within such GANs highly interacting (hub) genes can be identified, which are supposed to be high-level regulators connected to multiple processes. By exploring the intestinal expression of genes differing between control and Salmonella infected chicken in a time-dependent manner differences in GANs were found. In control chickens more developmental processes were observed, whereas in infected chickens relatively more processes were associated to 'defense/pathogen response'. Moreover the conserved protein domains of the identified hub genes in controls were nuclear-associated, whereas hub genes in infected chickens were involved in 'cellular communication'. The shift in topology and functionality of the intestinal GANs in control and Salmonella infected animals and the identification of GAN-specific hubs is a first step to understand the complexity of biological networks and processes regulating intestinal health and functionality under normal and disturbed conditions.

Genetic control of resistance to salmonellosis and to Salmonella carrier-state in fowl: a review

Salmonellosis is a frequent disease in poultry stocks, caused by several serotypes of the bacterial species Salmonella enterica and sometimes transmitted to humans through the consumption of contaminated meat or eggs. Symptom-free carriers of the bacteria contribute greatly to the propagation of the disease in poultry stocks. So far, several candidate genes and quantitative trait loci (QTL) for resistance to carrier state or to acute disease have been identified using artificial infection of S. enterica serovar Enteritidis or S. enterica serovar Typhimurium strains in diverse genetic backgrounds, with several different infection procedures and phenotypic assessment protocols. This diversity in experimental conditions has led to a complex sum of results, but allows a more complete description of the disease. Comparisons among studies show that genes controlling resistance to Salmonella differ according to the chicken line studied, the trait assessed and the chicken's age. The loci identified are located on 25 of the 38 chicken autosomal chromosomes. Some of these loci are clustered in several genomic regions, indicating the possibility of a common genetic control for different models. In particular, the genomic regions carrying the candidate genes TLR4 and SLC11A1, the Major Histocompatibility Complex (MHC) and the QTL SAL1 are interesting for more in-depth studies. This article reviews the main Salmonella infection models and chicken lines studied under a historical perspective and then the candidate genes and QTL identified so far.

A time-course study of gene responses of chicken granulosa cells to Salmonella Enteritidis infection

Consumption of eggs contaminated with Salmonella Enteritidis (SE) has been recognized as one of the important causes of human foodborne salmonellosis. Chicken granulosa cells (cGCs) comprise the last tissue layer surrounding the yolk in preovulatory follicles and are a preferred site for SE invasion. To understand the cGC response to SE infection, we conducted an in vitro time-course study to identify cGC transcriptional changes using chicken whole genome microarrays. The expression of 135 (4h postinfection) and 120 cGC genes (48 h postinfection) were altered (P<.01) compared to uninfected cells. Many of the altered genes were related to immune response, physiological processes, signal transduction, and transcription. Furthermore, we also found that the Jak-STAT pathway, which is essential in the regulation of cellular cytokines and growth factors, was highly active in this study. Among the genes identified by microarray, the mRNA levels of TLR15, IL-6, CXCLi1, CXCLi2, and K203 were shown to be upregulated by real-time RT-PCR (qRT-PCR). In contrast, the mRNA levels of RASD1 and HB-EGF decreased according to both microarray and qRT-PCR analyses. These results suggest that during the SE infection, cGCs recruit cells of the innate immune responses; the infection may also induce suppression of cGC cell proliferation, which alters follicular development and ovulation.

Genetic lines differ in Toll-like receptor gene expression in spleens of chicks inoculated with Salmonella enterica serovar Enteritidis

Toll-like receptors (TLR) recognize evolutionarily conserved molecular motifs (pathogen-associated molecular patterns) of infectious microbes and initiate innate immune response upon activation with relevant pathogens. This study investigated the acute effect of Salmonella Enteritidis challenge on TLR mRNA expression in cecum and spleen of birds from 3 distinct genetic lines. Chicks from broiler, Leghorn, and Fayoumi lines were inoculated or mock-inoculated with Salmonella Enteritidis. The mRNA expression levels of TLR2, TLR4, and TLR5 genes were assessed by quantitative reverse transcription-PCR of cecum and spleen tissue harvested at 2 or 18 h postinoculation (PI). There were no significant genetic line effects on TLR mRNA expression in spleen or cecum of mock-infected birds, or in the cecum of infected birds. Genetic line effect was significant (P < 0.05) on TLR mRNA expression in the spleen of Salmonella Enteritidis-infected birds. The Fayoumi line had higher TLR2 and TLR4 expression than Leghorn, higher TLR2 mRNA expression than broiler, and the broiler line had higher TLR5 expression than Leghorn and Fayoumi. In Salmonella Enteritidis-infected birds, the TLR2 expression in both cecum and spleen and TLR4 expression in spleen were significantly higher at 18 h PI than 2 h PI. The results demonstrate a significant genetic line effect on TLR expression in the spleen of Salmonella Enteritidis-infected birds, which may partly explain genetic variability in immune response to Salmonella Enteritidis.

Genotype-dependent tumor regression in Marek's disease mediated at the level of tumor immunity

Marek's disease (MD) of chickens is a unique natural model of Hodgkin's and Non Hodgkin's lymphomas in which the neoplastically-transformed cells over-express CD30 (CD30(hi)) antigen. All chicken genotypes can be infected with MD virus and develop microscopic lymphomas. From 21 days post infection (dpi) microscopic lymphomas regress in resistant chickens but, in contrast, they progress to gross lymphomas in susceptible chickens. Here we test our hypothesis that in resistant chickens at 21 dpi the tissue microenvironment is pro T-helper (Th)-1 and compatible with cytotoxic T lymphocyte (CTL) immunity but in susceptible lines it is pro Th-2 or pro T-regulatory (T-reg) and antagonistic to CTL immunity. We used the B2, non-MHC-associated, MD resistance/susceptibility system (line [L]6(1)/line [L]7(2)) and quantified the levels of key mRNAs that can be used to define Th-1 (IL-2, IL-12, IL-18, IFNgamma), Th-2 (IL-4, IL-10) and T-reg (TGFbeta, GPR-83, CTLA-4, SMAD-7) lymphocyte phenotypes. We measured gene expression in both whole tissues (represents tissue microenvironment and tumor microenvironment) and in the lymphoma lesions (tumor microenvironment) themselves. Gene ontology-based modeling of our results shows that the dominant phenotype in whole tissue as well as in microscopic lymphoma lesions, is pro T-reg in both L6(1) and L7(2) but a minor pro Th-1 and anti Th-2 tissue microenvironment exists in L6(1) whereas there is an anti Th-1 and pro Th-2 tissue microenvironment in L7(2). The tumor microenvironment per se is pro T-reg, anti Th-1 and pro Th-2 in both L6(1) and L7(2). Together our data suggests that the neoplastic transformation is essentially the same in both L6(1) and L7(2) and that resistance/susceptibility is mediated at the level of tumor immunity in the tissues.

Comparative in vivo infection models yield insights on early host immune response to Campylobacter in chickens

Salmonella typhimurium and Campylobacter jejuni pose significant risks to human health and poultry are a major vector for infection. Comparative in vivo infection models were performed to compare the avian host immune response to both bacterial species. Forty-five commercial broiler chickens were orally challenged with either C. jejuni or S. typhimurium whilst 60 similar control birds were mock challenged in parallel. Birds were sacrificed at 0, 6, 20 and 48 h post-infection and cloacal swabs, blood and tissue samples taken. Peripheral blood leukocytes were isolated for flow cytometric analyses and RNA was extracted for gene expression profiling. Colonisation patterns were markedly different between the two bacterial species, with systemic colonisation of Campylobacter outside the gastrointestinal tract. Salmonella infection induced significant changes in circulating heterophil and monocyte/macrophage populations, whilst Campylobacter infection had no effect on the heterophil numbers but caused a significant early increase in circulating monocytes/macrophages. Toll-like receptor 1 (TLR1) gene expression was decreased, and avian beta-defensin (AvBD) gene expression (AvBD3, AvBD10 and AvBD12) was significantly increased in response to Salmonella infection (P < 0.05). In contrast, Campylobacter infection induced increased TLR21 gene expression but significantly reduced expression of seven antimicrobial peptide (AMP) genes (AvBD3, AvBD4, AvBD8, AvBD13, AvBD14, CTHL2 and CTHL3; P < 0.05). Considered together, microbiological, cellular and gene expression profiles indicate that the innate immune system responds differently to Salmonella and to Campylobacter infection. Furthermore, reduction in the expression of AMPs may play a role in the persistence of high level colonisation of the host by Campylobacter.

The neoplastically transformed (CD30hi) Marek's disease lymphoma cell phenotype most closely resembles T-regulatory cells

INTRODUCTION

Marek's disease (MD), a herpesvirus-induced lymphoma of chickens is a unique natural model of CD30-overexpressing (CD30hi) lymphoma. We have previously proposed that the CD30hi neoplastically transformed CD4+ T cells in MD lymphomas have a phenotype antagonistic to cell mediated immunity. Here were test the hypothesis that the CD30hi neoplastically transformed MD lymphoma cells have a phenotype more closely resembling T-helper (Th)-2 or regulatory T (T-reg) cells.

MATERIALS AND METHODS

We separated ex vivo-derived CD30hi, from the CD30lo/- (non-transformed), MD lymphoma cells and then quantified the relative amounts of mRNA and proteins for cytokines and other genes that define CD4+ Th-1, Th-2 or T-reg phenotypes.

RESULTS AND DISCUSSION

Gene Ontology-based modeling of our data shows that the CD30hi MD lymphoma cells having a phenotype more similar to T-reg. Sequences that could be bound by the MD virus putative oncoprotein Meq in each of these genes' promoters suggests that the MD herpesvirus may play a direct role in maintaining this T-reg-like phenotype.

Toll-like receptor gene expression in cecum and spleen of advanced intercross line chicks infected with Salmonella enterica serovar Enteritidis

Understanding the changes in host gene expression that occur with bacterial infection will help to elucidate the basis of molecular genetic control of disease resistance. The effect of infecting chicks with Salmonella enterica serovar Enteritidis on the RNA expression level of Toll-like receptor (TLR) genes, and the correlation between TLR RNA expression level and bacterial burden in the cecum and spleen of young birds was studied. Chicks from two advanced intercross lines were either infected or mock infected with S. enteritidis at 1 day of age. The RNA expression levels of TLR2, TLR4 and TLR5 genes were assessed by quantitative reverse transcriptase-PCR (qRT-PCR) in cecum and spleen tissues harvested at one week post-infection. Infected chicks had significant upregulation of TLR2 RNA expression in spleen, TLR4 RNA expression in both cecum and spleen, and downregulation of TLR5 RNA expression in cecum. Bacterial burden of S. enteritidis in infected birds was not correlated with TLR RNA expression level. Infecting chicks with S. enteritidis caused an increase in TLR2, TLR4 and TLR5 RNA expression level in spleen in males but not in females. The effect of sex on response to S. enteritidis infection suggests a role for TLR signaling pathways in sex-based modulation of immune response to pathogens. High correlation between TLR2 and TLR4 mRNA expression level in cecum of S. enteritidis infected birds suggests coordinated regulation or simultaneous stimulation of these genes by S. enteritidis. In conclusion, this study clearly showed that young chicks respond to S. enteritidis infection by upregulating TLR2, TLR4 RNA expression. The downregulation of TLR5 RNA expression was observed in cecum by S. enteritidis infection, which might be beneficial to protect host cells from overstimulation by bacterial flagellin.

Expression profile of myostatin mRNA during the embryonic organogenesis of domestic chicken (Gallus gallus domesticus)

Myostatin is a potent growth and differentiation factor involved in skeletal muscle tissue formation in vertebrates. However, recent studies in chicken embryo suggested that the myostatin was expressed even before the establishment of myogenic lineage. No studies have thus far been reported in birds to define the role of myostatin during the embryonic organogenesis. The present experiment was designed for studying the expression profiles of myostatin mRNA in the chicken liver, heart, brain, and intestine during their morphogenesis, using real-time PCR. The myostatin mRNA expression was significantly upregulated in liver during E15-E18. Similar results were observed during the development of chicken heart. In brain, the expression of myostatin was upregulated from E4 onwards. In intestine, the expression of myostatin was significantly increased many folds on E9-E18. Therefore, the increase in myostatin expression might be related to the growth of liver and heart on days E12-E18; morphogenesis and growth of brain during E15-E18; and morphogenesis and differentiation of intestine during E9-E18. In the present study, the tissue-specific expression of myostatin gene in chicken is similar to fishes, but different from that in mammals. Further, the inspection of chicken genome also suggested that there is no differentiation of GDF-8 and -11. A recent finding suggests that the chicken myostatin gene is closely related to mammals than fishes. Therefore, we propose that the chicken myostatin gene might have diverged in its function between teleosts and mammals. Indeed it is possible that its function might have only become fully differentiated to serve as a control of muscle mass in mammals.

Differential alterations in ultrastructural morphology of chicken heterophils and lymphocytes induced by corticosterone and lipopolysaccharide

Birds are continuously confronted by a large number of stressors, including pathogens. Despite their variety, all stressors induce an elevation in plasma corticosterone concentration, and consequently increase heterophil to leukocyte (H/L) ratio. In order to evaluate and differentiate effects of endocrine (non-bacterial) and bacterial stress on the proportions and ultrastructural characteristics of chicken leukocytes, a series of experiments were conducted with seven-week old chickens exposed either to dietary corticosterone or to intravenous (i.v.)-injected lipopolysaccharide (LPS). Samples were taken for haematological, endocrine, and electron microscopy examination. Administration of corticosterone and LPS significantly elevated plasma corticosterone concentrations and increased H/L ratios. Electron microscopy observations indicated changes in heterophil size, shape, and granulation, and lymphocyte cytoplasmic characteristics. Immature heterophils were observed in the peripheral blood, suggesting that corticosterone and LPS both stimulate an earlier release of heterophils from bone marrow and enhance their influx into blood circulation. The LPS induced a degenerative morphology and the destruction of lymphocytes, whereas corticosterone appeared to stimulate their redistribution rather than destruction. The results indicate that exposure to corticosterone or LPS similarly increase H/L ratios, but differentially alter the ultrastructure of heterophils and lymphocytes. Elucidation of the mechanisms that cause such changes may play an important role in distinguishing between a nonimmune and immune stress challenge at the molecular level.