Discrimination of distinct chicken M cell subsets based on CSF1R expression

In mammals, a subset of follicle-associated epithelial (FAE) cells, known as M cells, conduct the transcytosis of antigens across the epithelium into the underlying lymphoid tissues. We previously revealed that M cells in the FAE of the chicken lung, bursa of Fabricius (bursa), and caecum based on the expression of CSF1R. Here, we applied RNA-seq analysis on highly enriched CSF1R-expressing bursal M cells to investigate their transcriptome and identify novel chicken M cell-associated genes. Our data show that, like mammalian M cells, those in the FAE of the chicken bursa also express SOX8, MARCKSL1, TNFAIP2 and PRNP. Immunohistochemical analysis also confirmed the expression of SOX8 in CSF1R-expressing cells in the lung, bursa, and caecum. However, we found that many other mammalian M cell-associated genes such as SPIB and GP2 were not expressed by chicken M cells or represented in the chicken genome. Instead, we show bursal M cells express high levels of related genes such as SPI1. Whereas our data show that bursal M cells expressed CSF1R-highly, the M cells in the small intestine lacked CSF1R and both expressed SOX8. This study offers insights into the transcriptome of chicken M cells, revealing the expression of CSF1R in M cells is tissue-specific.

BPA and low-Se exacerbate apoptosis and autophagy in the chicken bursa of Fabricius by regulating the ROS/AKT/FOXO1 pathway

Bisphenol A (BPA) is a ubiquitous environmental pollutant that can have harmful effects on human and animal immune systems by inducing oxidative stress. Selenium (Se) deficiency damages immune organ tissues and exhibits synergistic effects on the toxicity of environmental pollutants. However, oxidative stress, cell apoptosis, and autophagy caused by the combination of BPA and low-Se, have not been studied in the bursa of Fabricius of the immune organ of poultry. Therefore, in this study, BPA and/or low-Se broiler models and chicken lymphoma cells (MDCC-MSB-1 cells) models were established to investigate the effects of BPA and/or low-Se on the bursa of Fabricius of poultry. The data showed that BPA and/or low-Se disrupted the normal structure of the bursa of Fabricius, BPA (60 μM) significantly reduced the activity of MDCC-MSB-1 cells and disrupted normal morphology (IC50 = 192.5 ± 1.026 μM). Compared with the Control group, apoptosis and autophagy were increased in the BPA or low-Se groups, and the generation of reactive oxygen species (ROS) was increased. This inhibited the AKT/FOXO1 pathway, leading to mitochondrial fusion/division imbalance (Mfn1, Mfn2, OPA1 were increased, DRP1 was decreased) and dysfunction (CI-NDUFB8, CII-SDHB, CIII-UQCRC2, CIV-MTCO1, CV-ATP5A1, ATP). Furthermore, combined exposure of BPA and low-Se aggravated the above-mentioned changes. Treatment with N-acetylcysteine (NAC) reduced ROS levels and activated the AKT/FOXO1 pathway to further alleviate BPA and low-Se-induced apoptosis and autophagy. Apoptosis induced by low-Se + BPA was exacerbated after 3-Methyladenine (3-MA, autophagy inhibitor) treatment. Together, these results indicated that BPA and low-Se aggravated apoptosis and autophagy of the bursa of Fabricius in chickens by regulating the ROS/AKT/FOXO1 pathway.

Penthorum chinense Prush extract alleviates aflatoxin B1-induced toxicity, oxidative stress and apoptosis via mediating Nrf2 signaling pathway in the Bursa of Fabricius of broilers

Aflatoxin B1 (AFB1) is the primary mycotoxin that is responsible for the severe issues plaguing poultry farming. The study was aimed to explore the relevant pathways connected with immunity (inflammation, oxidative stress and apoptosis) in an AFB1-challenged chicken by using Penthorum chinense Prush extract (PCPE) in Bursa of Fabricius (BF) of broilers. A total one hundred and eighty day-old broilers were divided into six groups: Control, AFB1 (3 mg/kg feed), Yin-Chen-Hao Tang extract (YCHT) (10 ml/kg feed), and PCPE groups (low 1 g/kg, medium 2 g/kg, and high 3 g/kg PCPE/kg feed) respectively. The results showed that AFB1-challenged birds showed significant decrease in growth, BF weight index, serum antioxidant biomarkers and histopathological changes in BF tissues. The mRNA analysis showed that AFB1 upregulated the apoptosis associated genes (caspase-3, caspase-9, Bak, Bax and p53) and downregulated BCL-2. Additionally, AFB1 downregulated expression level of Nuclear Factor EF-2 (Nrf2) related genes (Nrf2, HO-1, NQO1 and GCLC) in the BF of broilers. The PCPE treatment showed positive impact on final weight gain, bursal index, and reversing of pathological changes in the BF of AFB1-challanged broilers. PCPE ameliorated oxidative stress generated by AFB1, as an increase in antioxidant enzyme activities, alleviated histopathological changes in BF, enhanced the Nrf2 expression levels and lowered the apoptosis gene expressions as compared to AFB1. The findings revealed that PCPE activated the Nrf2 pathway, antioxidant defense system and modulated the apoptosis in the BF of broiler chicken.

In ovo feeding of probiotic lactobacilli differentially alters expression of genes involved in the development and immunological maturation of bursa of Fabricius in pre-hatched chicks

Compelling evidence indicates that immunological maturation of the gut-associated lymphoid tissues, including the bursa of Fabricius, is dependent upon antigenic stimulation post-hatch. In view of these data, the present study investigated the impact of exposing the immune system of chick embryos to antigenic stimuli, via in ovo delivery of poultry-specific lactobacilli, on the expression of genes associated with early bursal development and maturation. Broiler line embryonated eggs were inoculated with 106 and 107 colony-forming units (CFUs) of an individual or a mixture of Lactobacillus species, including L. crispatus (C25), L. animalis (P38), L. acidophilus (P42), and L. reuteri (P43), at embryonic day 18 (ED18). The bursa of Fabricius was collected from pre-hatched chicks (ED20) to measure the expression levels of various immune system genes. The results revealed that L. acidophilus and the mixture of Lactobacillus species at the dose of 106 CFU consistently elicited higher expression of genes responsible for B cell development, differentiation, and survival (B cell activating factor (BAFF), BAFF-receptor (BAFF-R)), and antibody production (interleukin (IL)-10) and diversification (TGF-β). Similar expression patterns were also noted in T helper (Th) cell-associated cytokine genes, including Th1-type cytokines (interferon (IFN)-γ and IL-12p40), Th2-type cytokines (IL-4 and IL-13) and Th17 cytokine (IL-17). Overall, these results suggest that the supplementation of poultry-specific lactobacilli to chick embryos might be beneficial for accelerating the development and immunological maturation of the bursa of Fabricius. However, further studies are required to determine if the changes in gene expression are associated with the developmental trajectory and phenotypes of bursal cells.

HSP27-HSP40-HSP70-HSP90 pathway participated in molecular mechanism of selenium alleviating lead-caused oxidative damage and proteotoxicity in chicken Bursa of Fabricius

Lead (Pb), a toxic environmental pollutant, is hazardous to the health of humans and birds. Bursa of Fabricius (BF) is a unique organ of birds. Toxic substances can attack BF and induce proteotoxicity. Increased heat shock proteins (HSPs) can induce oxidative damage. Selenium (Se) can alleviate harmful substance-caused oxidative damage. This study aimed to investigate whether Pb can cause oxidative damage and proteotoxicity, as well as Se reverse Pb-caused chicken BF toxicity. A model of chickens treated with Se and Pb alone and in combination was established. BFs were collected on days 30, 60, and 90. H&E and qRT-PCR were performed to observe the microstructure and to detect HSP27, HSP40, HSP60, HSP70, and HSP90 mRNA levels, respectively, in BFs. Multivariate correlation analysis and principal component analysis were conducted to explore the correlation among the five HSPs. In our results, Pb caused BF damage and up-regulated the five HSPs at three time points, causing oxidative damage and proteotoxicity via HSP27-HSP40-HSP70-HSP90 pathway. Furthermore, Pb caused time-dependent stress on HSP27, HSP40, HSP60, and HSP70. In addition, Se relieved Pb-caused damage and up-regulation of HSPs. Taken together, we concluded that Se alleviated Pb-caused oxidative injury and proteotoxicity in chicken BFs via the HSP27-HSP40-HSP70-HSP90 pathway.

Intergrated Transcriptomic and Proteomic Analysis Revealed the Differential Responses to Novel Duck Reovirus Infection in the Bursa of Fabricius of Cairna moschata

The bursa of Fabricius is an immunologically organ against the invasion of duck reovirus (DRV), which is a fatal bird virus belonging to the Reoviridae family. However, responses of the bursa of Fabricius of Cairna moschata to novel DRV (NDRV) infection are largely unknown. Transcriptomes and proteomes of the samples from control and two NDRV strain (HN10 and JDm10) with different virulence were analyzed. Differentially expressed genes and differential accumulated proteins were enriched in the serine protease system and innate immune response clusters. Most of the immune-related genes were up-regulated under both JDm10/HN10 infections. However, the immune-related proteins were only accumulated under HN10 infection. For the serine protease system, coagulation factor IX, three chains of fibrinogen, and complements C8, C5, and C2s were significantly up-regulated by the HN10 infection, suggesting that the serine protease-mediated immune system might be involved in the resistance to NDRV infection. For the innate and adaptive immune system, RIG-I, MDA5, MAPK20, and IRF3 were significantly up-regulated, indicating their important roles against invaded virus. TLR-3 and IKBKB were only up-regulated in the liver cells, MAPK20 was only up-regulated in the bursa of Fabricius cells, and IRAK2 was only up-regulated in the spleen samples. Coagulation factor IX was increased in the bursa of Fabricius, not in the liver and spleen samples. The data provides a detailed resource for studying the proteins participating in the resistances of the bursa of Fabricius of duck to NDRV infections.

Selenium Deficiency Induces Autophagy in Chicken Bursa of Fabricius Through ChTLR4/MyD88/NF-κB Pathway

To explore the role of ChTLR4/MyD88/NF-κB signaling pathway on autophagy induced by selenium (Se) deficiency in the chicken bursa of Fabricius, autophagosome formation in the bursa of Fabricius was observed by transmission electron microscopy. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression of ChTLR4 and its signaling pathway molecules (MyD88, TRIF, and NF-κB), inflammatory factors (IL-1β, IL-8, and TNF-α), and autophagy-related factors (ATG5, Beclin1, and LC3-II) in the Se-deficient chicken bursa of Fabricius at different ages. The results showed that ChTLR4/MyD88/NF-κB signaling pathway was activated in the chicken bursa of Fabricius and autophagy was induced at the same time by Se deficiency. In order to verify the relationship between the autophagy and ChTLR4/MyD88/NF-κB signaling pathway, HD11 cells were used to establish the normal C group, low Se group, and low Se + TLR4 inhibitor (TAK242) group. The results demonstrated that autophagy could be hindered when the TLR4 signaling pathway was inhibited under Se deficiency. Furthermore, autophagy double-labeled adenovirus was utilized to verify the integrity of autophagy flow induced by Se deficiency in HD11 cells. The results showed that it appeared to form a complete autophagy flow under the condition of Se deficiency and could be blocked by TAK242. In summary, we found that Se deficiency was involved in the chicken bursa of Fabricius autophagy occurring by activating the ChTLR4/MyD88/NF-κB pathway.

1,8-cineole alleviates bisphenol A-induced apoptosis and necroptosis in bursa of Fabricius in chicken through regulating oxidative stress and PI3K/AKT pathway

Bisphenol A (BPA), an important chemical raw material, is now a ubiquitous environmental contaminant. As an endocrine disruptor similar to estrogen, BPA increases the risk of various metabolic and chronic diseases. BPA has immunotoxicity to humans and animals. 1,8-cineole (CIN) is a plant-derived monoterpene with antioxidant and antiapoptosis actions. However, there are no reports about whether CIN could antagonize the BPA-induced apoptosis and necroptosis in bursa of Fabricius (BF) of chicken. This study was to elucidate the ameliorative mechanism of CIN on the apoptosis and necroptosis in BF induced by BPA. 120 broilers (1-day-old) were randomly divided into four groups: control group, CIN group, CIN and BPA co-treatment group, and BPA group. TUNEL analysis results, histopathological variations, and the overexpression of proapoptosis biomakers (Caspase 3, Bax, Cyt-c, and p53) and necroptosis pathway-related factors (RIPK1, RIPK3, MLKL, and FADD) indicated that BPA exposure induced the apoptosis and necroptosis in chicken BF. Moreover, BPA treatment elevated the levels of oxidative stress indexes (MDA, iNOS, and NO) and weaken antioxidases activity (SOD, GPx, and CAT) and total antioxidant capacity in chicken BF. BPA administration also lessened the expression of PI3K and AKT and promoted HSPs (HSP27, HSP40, HSP60, and HSP70) activation. whereas CIN supplementation prominently mitigated BPA-caused these changes and the apoptosis and necroptosis damages. In brief, this study illuminated that CIN could protect the chicken BF against BPA-induced apoptosis and necroptosis through restraining oxidative stress and activating PI3K/AKT pathway.

Regulation of H2S-induced necroptosis and inflammation in broiler bursa of Fabricius by the miR-15b-5p/TGFBR3 axis and the involvement of oxidative stress in this process

Hydrogen sulfide (H₂S) is an air pollutant, having toxic effects on immune system. Necroptosis has been discussed as a new form of cell death and plays an important role in inflammation. To investigate the mechanism of H₂S-induced immune injury, and the role of microRNAs (miRNAs) in this process, based on the results of high-throughput sequencing, we selected the most significantly changed miR-15b-5p for subsequent experiments. We further predicted and determined the targeting relationship between miR-15b-5p and TGFBR3 in HD11 through miRDB, Targetscan and dual-luciferase, and found that miR-15b-5p is highly expressed in H₂S-induced necroptosis and inflammation. To understand whether miR-15b-5p/TGFBR3 axis could involve in the process of necroptosis and inflammation, we further revealed that the high expression of miR-15b-5p and the knockdown of TGFBR3 can induce necroptosis. Nec-1 treatment enhanced the survival rate of cells. Notably, H₂S exposure induces oxidative stress and activates the TGF-β pathway, which are collectively regulated by the miR-15b-5p/TGFBR3 axis. Our present study provides a new perspective for necroptosis regulated by the miR-15b-5p/TGFBR3 axis and reveals a new form of inflammation regulation in immune diseases.

Gut microbiota is associated with protection against Marek's disease virus infection in chickens

Marek's Disease Virus (MDV) infects chickens via respiratory route and causes lymphomas in internal organs including gastrointestinal tract. MDV infection causes a shift in the gut microbiota composition. However, interactions between the gut microbiota and immune responses against MDV infection are not well understood. Therefore, the current study was performed to understand the effect of the gut microbiota on Marek's disease (MD) pathogenesis. The findings showed that depletion of gut microbiota increased the severity of MD in infected chickens. In addition, an increase in the transcription of interferon (IFN)-α, IFN-β and IFN-γ in the bursa of Fabricius at 4 days post-infection (dpi) was observed in the gut microbiota depleted chickens. The observations in this study shed more light on the association between the gut microbiota and MDV infection in chickens. More research is needed to explore the mechanisms of involvement of the gut microbiota in immunity against MD in chickens.

Very virulent infectious bursal disease virus-induced immune injury is involved in inflammation, apoptosis, and inflammatory cytokines imbalance in the bursa of fabricius

Infectious bursal disease virus (IBDV) can cause a highly contagious disease in young chickens, resulting in bursal necrosis that causes severe damage to the immune system. The effects of various IBDV strains on the bursa of Fabricius (BF) have been extensively studied; however, few studies have investigated the effects of IBDV strain LJ-5, a newly discovered very virulent IBDV (vvIBDV), infection on young chicken BF. In this study, three-week-old specific pathogen-free (SPF) chickens were infected with vvIBDV for one to five days. LJ-5 decreased the bursa index, B lymphocyte viability and immunoglobulin (Ig) levels, including IgM and IgA in the bursa and IgY in the sera. Histopathological analysis revealed necrosis and depletion of the lymphoid cells and complete loss of bursal architecture in the BF, and transmission electron microscopy revealed mitochondrial vacuoles, cristae breaks, and nuclear damage in vvIBDV-infected bursa tissue. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling-positive nuclei significantly increased following IBDV infection. Cytokine levels increased in the bursa after IBDV infection, promoting inflammation and causing an inflammatory imbalance. Apoptotic gene expression confirmed that vvIBDV infection promotes the apoptosis of bursal cells. These results suggest that vvIBDV infection attenuate immune responses by reducing B lymphocyte activity of secretion Ig in the bursa or sera and triggers inflammation, apoptosis, and an imbalance of inflammatory cytokines in the BF, resulting in immune injury in SPF chickens, which offered basic data for further study of vvIBDV pathogenesis.

Recombinant hemagglutinin glycoproteins provide insight into binding to host cells by H5 influenza viruses in wild and domestic birds

Clade 2.3.4.4, H5 subtype highly pathogenic avian influenza viruses (HPAIVs) have caused devastating effects across wild and domestic bird populations. We investigated differences in the intensity and distribution of the hemagglutinin (HA) glycoprotein binding of a clade 2.3.4.4 H5 HPAIV compared to a H5 low pathogenic avian influenza virus (LPAIV). Recombinant HA from gene sequences from a HPAIV, A/Northern pintail/Washington/40964/2014(H5N2) and a LPAIV, A/mallard/MN/410/2000(H5N2) were generated and, via protein histochemistry, HA binding in respiratory, intestinal and cloacal bursal tissue was quantified as median area of binding (MAB). Poultry species, shorebirds, ducks and terrestrial birds were used. Differences in MAB were observed between the HPAIV and LPAIV H5 HAs. We demonstrate that clade 2.3.4.4 HPAIV H5 HA has a broader host cell binding across a variety of bird species compared to the LPAIV H5 HA. These findings support published results from experimental trials, and outcomes of natural disease outbreaks with these viruses.

Copper induces oxidative stress with triggered NF-κB pathway leading to inflammatory responses in immune organs of chicken

Copper (Cu) is a necessary trace mineral due to its biological activity. Excessive Cu can induce inflammatory response in humans and animals, but the underlying mechanism is still unknown. Here, 240 broilers were used to study the effects of excessive Cu on oxidative stress and NF-κB-mediated inflammatory responses in immune organs. Chickens were fed with diet containing different concentrations of Cu (11, 110, 220, and 330 mg of Cu/kg dry matter). The experiment lasted for 49 days. Spleen, thymus, and bursa of Fabricius (BF) on day 49 were collected for histopathological observation and assessment of oxidative stress status. Additionally, the mRNA and protein levels of NF-κB and inflammatory cytokines were also analyzed. The results indicated that excess Cu could increase the number and area of splenic corpuscle as well as the ratio of cortex and medulla in thymus and BF. Furthermore, excessive Cu intake could decrease activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px); but increase contents of malondialdehyde (MDA), TNF-α, IL-1, IL-1β; up-regulate mRNA levels of TNF-α, IFN-γ, IL-1, IL-1β, IL-2, iNOS, COX-2, NF-κB and protein levels of TNF-α, IFN-γ, NF-κB, p-NF-κB in immune organs. In conclusion, excessive Cu could cause pathologic changes and induce oxidative stress with triggered NF-κB pathway, and might further regulate the inflammatory response in immune organs of chicken.

Regulation and function of macrophage colony-stimulating factor (CSF1) in the chicken immune system

Macrophage colony-stimulating factor (CSF1) is an essential growth factor to control the proliferation, differentiation and survival of cells of the macrophage lineage in vertebrates. We have previously produced a recombinant chicken CSF1-Fc fusion protein and administrated it to birds which produced a substantial expansion of tissue macrophage populations. To further study the biology of CSF1 in the chicken, here we generated anti-chicken CSF1 antibodies (ROS-AV181 and 183) using CSF1-Fc as an immunogen. The specific binding of each monoclonal antibody was confirmed by ELISA, Western blotting and immunohistochemistry on tissue sections. Using the anti-CSF1 antibodies, we show that chicken bone marrow derived macrophages (BMDM) express CSF1 on their surface, and that the level appears to be regulated further by exogenous CSF1. By capture ELISA circulating CSF1 levels increased transiently in both layer and broiler embryos around the day of hatch. The levels of CSF1 in broilers was higher than in layers during the first week after hatch. Antibody ROS-AV183 was able to block CSF1 biological activity in vitro and treatment of hatchlings using this neutralising antibody in vivo impacted on some tissue macrophage populations, but not blood monocytes. After anti-CSF1 treatment, CSF1R-transgene reporter expressing cells were reduced in the bursa of Fabricius and cecal tonsil and TIM4⁺ Kupffer cells in the liver were almost completely ablated. Anti-CSF1 treatment also produced a reduction in overall bone density, trabecular volume and TRAP⁺ osteoclasts. Our novel neutralising antibody provides a new tool to study the roles of CSF1 in birds.

Ammonia inhalation impaired immune function and mitochondrial integrity in the broilers bursa of fabricius: Implication of oxidative stress and apoptosis

Ammonia (NH₃) is considered as environmental pollutant and toxic agent for animals and humans including poultry. Previous reports demonstrated that NH₃ suppressed broilers immunity. However, the harmful effects of NH₃ on broilers bursa of fabricius (BF) is still unknown. Functionally, apoptosis is very important for many physiological processes including homeostasis of lymphocyte population. Therefore, the present study was aimed to investigate the underlying mechanisms of NH₃ toxicity in the broilers BF. Histological observation showed lymphocyte accumulation, cavities and increased interstitial cells in BF. Ultrastructural observation indicated mitochondrial vacuoles, deformation and disappearance of mitochondrial membranes. Oxidative stress markers (CAT, MDA, H₂O₂, GGT, GSH-Px and GSH) showed that NH₃-induced oxidative stress in BF. Meanwhile, Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay revealed increased apoptotic cells. In addition, the mRNA and protein expression of dynamin-related protein 1 (Drp1), mitochondrial fission factor (Mff), mitofusin 1 and 2 (Mfn1 and Mfn2), optic atrophy 1 (Opa1) indicated imbalance between mitochondrial inner and outer membrane and results in mitochondrial dysfunction in broilers BF. The mRNA and protein expression of apoptosis-related genes including Caspase-3, Caspase-9, Caspase-8, Cytochrome-C (Cyt-C), p53, B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X protein (Bax) were significantly altered in broilers BF. Conclusively, these results displayed that excessive NH₃ causes BF damage and mitochondrial dysfunction through oxidative stress and apoptosis in BF and could affect immune function of BF. These findings provide possible therapeutic targets to prevent NH₃ induced toxicity in the BF of broilers.

MicroRNA profiling in the bursae of Marek's disease virus-infected resistant and susceptible chicken lines

Marek's disease (MD) is a lymphoproliferative disease of domestic chickens caused by a cell-associated oncogenic alpha-herpesvirus, Marek's disease virus (MDV). Clinical signs of MD include bursal/thymic atrophy, neurologic disorders, and T cell lymphomas. MiRNAs play key roles in regulation of gene expression by targeting translational suppression or mRNA degradation. MDV encodes miRNAs that are associated with viral pathogenicity and oncogenesis. In this study, we performed miRNA sequencing in the bursal tissues, non-tumorous but viral-induced atrophied lymphoid organ, from control and infected MD-resistant and susceptible chickens at 21 days post infection. In addition to some known miRNAs, a minimum of 300 novel miRNAs were identified in each group that mapped to the chicken genome with no sequence homology to existing miRNAs in chicken miRbase. Comparative analysis identified 54 deferentially expressed miRNAs between the chicken lines that might shed light on underlying mechanism of bursal atrophy and resistance or susceptibility to MD.

Oxidative damage under As3+ and/or Cu2+ stress leads to apoptosis and autophagy and may be cross-talking with mitochondrial disorders in bursa of Fabricius

Arsenic (As) exists in many forms in the whole natural environment, with As³⁺ the highest toxicity. Herein our study demonstrated that arsenic trioxide (As₂O₃) at a dose of 30 mg/kg caused serious oxidative damage to chickens' bursa of Fabricius (BF) in a time-dependent manner. Copper (Cu) is a necessary micronutrient and a key catalytic cofactor of many enzymes. We found excessive Cu (in the form of 300 mg/kg copper sulfate (CuSO₄)) also induced severe oxidative stress (OxS), and its co-exposure with As³⁺ had a greater destructive power against oxidative system. Under electron microscope, swollen mitochondria, disappeared cristae and agglutinated chromatin were observed, accompanied by myeloid structure and autophagosome. The results showed apoptosis and autophagy occurred under the action of As³⁺ and Cu²⁺, and the situation was more serious in combined exposure group, which was further explained by terminal deoxynucleotidyl transferase (TdT)-mediated 2'-Deoxyuridine 5'-Triphosphate (dUTP) Nick-End Labeling (TUNEL). By quantitative real time polymerase chain reaction (RT-qPCR) and western blot, we found that mitochondrial dynamics were disordered under OxS, and the abnormal changes of B-cell lymphoma (Bcl)-2, p53, Bcl-2-interacting protein (Beclin)-1 and autophagy-related gene (ATG) 4B indicated the crosstalk between apoptosis and autophagy. In conclusion, apoptosis and autophagy of BF induced by As³⁺ and Cu²⁺ and mitochondrial disorder are closely related to the collapse of antioxidant system, and their connections are inseparable. Our results provide a reference for environmental risk prevention and selection of poultry feed additives and pesticides to avoid the health risks caused by As³⁺ and Cu²⁺ exposure.

Developmental exposure to a mixture of perfluoroalkyl acids (PFAAs) affects the thyroid hormone system and the bursa of Fabricius in the chicken

Perfluoroalkyl acids (PFAAs) are ubiquitous environmental contaminants and eggs and nestlings of raptors and fish-eating birds often contain high levels of PFAAs. We studied developmental effects of a mixture of ten PFAAs by exposing chicken embryos to 0.5 or 3 μg/g egg of each compound in the mixture. Histological changes of the thyroid gland were noted at both doses and increased expression of mRNA coding for type III deiodinase was found at 0.5 μg/g egg. Serum concentrations of the free fraction of thyroid hormones (T3 and T4) were reduced by the PFAA mixture at 3 µg/g egg, which is in line with a decreased synthesis and increased turnover of thyroid hormones as indicated by our histological findings and the decreased mRNA expression of type III deiodinase. The relative weight of the bursa of Fabricius increased at a dose of 3 μg/g egg in females. The bursa is the site of B-cell development in birds and is crucial for the avian adaptive immune system. Analysis of plasma and liver concentrations of the mixture components showed differences depending on chain length and functional group. Our results highlight the vulnerability of the thyroid hormone and immune systems to PFAAs.

Proanthocyanidins Alleviates AflatoxinB₁-Induced Oxidative Stress and Apoptosis through Mitochondrial Pathway in the Bursa of Fabricius of Broilers

Aflatoxin B₁ (AFB₁) is a serious threat to the poultry industry. Proanthocyanidins (PCs) demonstrates a broad range of biological, pharmacological, therapeutic, and chemoprotective properties. The aim of this study was to investigate the ameliorative effects of PCs against AFB₁-induced histopathology, oxidative stress, and apoptosis via the mitochondrial pathway in the bursa of Fabricius (BF) of broilers. One hundred forty-four one-day old Cobb chicks were randomly assigned into four treatment groups of six replicates (6 birds each replicate) for 28 days. Groups were fed on the following four diets; (1) Basal diet without addition of PCs or AFB₁ (Control); (2) basal diet supplemented with 1 mg/kg AFB₁ from contaminated corn (AFB₁); (3) basal diet supplemented with 250 mg/kg PCs (PCs); and (4) basal diet supplemented with 1 mg/kg AFB₁ + 250 mg/kg PCs (AFB₁+ PCs). The present study results showed that antioxidant enzymes activities of total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione S-transferase (GST) in AFB₁ treated group were (p < 0.05) decreased, whereas malondialdehyde (MDA) contents were significantly increased in comparison with the control group. Furthermore, we found that dietary PCs treatment ameliorated AFB₁-induced oxidative stress in the BF through inhibiting the accumulation of MDA content and enhancing the antioxidant enzymes activities (T-SOD, CAT, GSH-Px, and GST). Similarly, PCs markedly enhanced messenger RNA (mRNA) expression of antioxidant genes (SOD, CAT, GPx1, and GST) in comparison with AFB₁ group. Moreover, histological results showed that PCs alleviated AFB₁-induced apoptotic cells in the BF of broilers. In addition, both mRNA and protein expression results manifested that mitochondrial-apoptosis-associated genes (Bax, caspase-9, caspase-3, and p53 and cytochrome c) showed up-regulation, while (Bcl-2) showed down-regulation in AFB₁ fed group. The supplementation of PCs to AFB₁ diet significantly reversed the mRNA and protein expression of these apoptosis-associated genes, as compared to the AFB₁ group. Our results demonstrated that PCs ameliorated AFB₁-induced oxidative stress by modulating the antioxidant defense system and apoptosis in the BF through mitochondrial pathway in broilers.

Lower Selenoprotein T Expression and Immune Response in the Immune Organs of Broilers with Exudative Diathesis Due to Selenium Deficiency

The objective of the present study was to investigate whether dietary selenium (Se) deficiency would affect the expression of selenoprotein T (SelT) and immune response in the immune organs of broilers. Changes in expression of inflammatory cytokines and oxidative stress response caused by Se deficiency can lead to organism damage, which in turn leads to immune response. Sixty (1-day-old) broilers were divided into the control group and Se-deficiency group. Animal models with exudative diathesis were duplicated in the broilers by feeding them Se-deficient diet for 20 days. After the Se-deficient group exhibited symptoms of exudative diathesis, all the broilers were euthanized, and their immune organs were taken for analysis. The tissues including spleen, bursa of Fabricius, and thymus were treated to determine the pathological changes (including microscopic and ultramicroscopic), the messenger RNA (mRNA) expression levels of SelT and its synthetase (SecS and SPS1), cytokine mRNA expression levels, and antioxidant status. The microscopic and ultramicroscopic analyses showed that immune tissues were obviously injured in the Se-deficient group. The mRNA expression of SelT was decreased compared with that in the control group. Meanwhile, the mRNA expression levels of SecS and SPS1 were downregulated. In the Se-deficient group, the mRNA expression levels of IL-1R and IL-1β were higher than those of three control organs. Additionally, the IL-2 and INF-γ mRNA expression levels were lower than those of the control group. The activity of CAT was decreased, and the contents of H₂O₂ and •OH were increased due to Se deficiency. Pearson method analysis showed that the expression of SelT had a positive correlation with IL-2, INF-γ, SecS, and SPS1 and a negative correlation with IL-1R and IL-1β. In summary, these data indicated that Se-deficient diet decreased the SelT expression and its regulation of oxidative stress, and it inhibited a pleiotropic mechanism of the immune response.

Influence of Graded Levels of l-Theanine Dietary Supplementation on Growth Performance, Carcass Traits, Meat Quality, Organs Histomorphometry, Blood Chemistry and Immune Response of Broiler Chickens

l-theanine is a water-soluble non-proteinous amino acid mainly found in green tea leaves. Despite the availability of abundant literature on green tea, studies on the use of l-theanine as a feed additive in animals, and especially broilers are limited. The objective of this study was, therefore, to evaluate the effect of different dietary levels of l-theanine on meat quality, growth performance, immune response, and blood metabolites in broilers. A total of 400 day-old broiler chicks were randomly divided into four treatment groups using a completely randomized design; C-control, basal diet; 100LT-basal diet + 100 mg l-theanine/kg diet; 200LT-basal diet + 200 mg l-theanine/kg diet; and 300LT-basal diet + 300 mg l-theanine/kg diet. Results revealed that the intermediate level of l-theanine (200 mg/kg diet) showed better results in terms of body weight gain (BWG), feed consumed (FC), and feed conversion ratio (FCR) as compared with the other supplemented groups and the control. The live weight eviscerated weight and gizzard weight were higher in all l-theanine levels as compared to those of the control group. Increased weight (p ≤ 0.05) of spleen and bursa were found in group 200LT (200 mg l-theanine/kg diet). Concerning meat color parameters, values for yellowness (b*), and redness (a*) were greater in l-theanine-supplemented groups than the control. Supplementing broiler diet with l-theanine reduced (p = 0.02) total serum cholesterol contents while increased HDL. Further analysis revealed lower relative serum cytokines (IL-2 and INF-γ) and reduced mRNA expression of TNF-α and IL-6 in thymus, and IFN-γ and IL-2 in spleen in the treated group. Moreover, supplementation with 200 mg/kg of l-theanine improved antioxidant status in blood by increasing SOD, GSH-Px, and relative CAT levels. It is concluded that the optimum supplementation level of l-theanine is 200 mg/kg of diet because it resulted in improved performance parameters in broilers. However, higher levels of l-theanine (300 mg/kg diet) may have deleterious effects on performance and health of broiler chickens.

Bursal transcriptome profiling of different inbred chicken lines reveals key differentially expressed genes at 3 days post-infection with very virulent infectious bursal disease virus

Infectious bursal disease is a highly contagious disease in the poultry industry and causes immunosuppression in chickens. Genome-wide regulations of immune response genes of inbred chickens with different genetic backgrounds, following very virulent infectious bursal disease virus (vvIBDV) infection are poorly characterized. Therefore, this study aims to analyse the bursal tissue transcriptome of six inbred chicken lines 6, 7, 15, N, O and P following infection with vvIBDV strain UK661 using strand-specific next-generation sequencing, by highlighting important genes and pathways involved in the infected chicken during peak infection at 3 days post-infection. All infected chickens succumbed to the infection without major variations among the different lines. However, based on the viral loads and bursal lesion scoring, lines P and 6 can be considered as the most susceptible lines, while lines 15 and N were regarded as the least affected lines. Transcriptome profiling of the bursa identified 4588 genes to be differentially expressed, with 2985 upregulated and 1642 downregulated genes, in which these genes were commonly or uniquely detected in all or several infected lines. Genes that were upregulated are primarily pro-inflammatory cytokines, chemokines and IFN-related. Various genes that are associated with B-cell functions and genes related to apoptosis were downregulated, together with the genes involved in p53 signalling. In conclusion, bursal transcriptome profiles of different inbred lines showed differential expressions of pro-inflammatory cytokines and chemokines, Th1 cytokines, JAK-STAT signalling genes, MAPK signalling genes, and their related pathways following vvIBDV infection.

Aflatoxin B1 affects apoptosis and expression of Bax, Bcl-2, and Caspase-3 in thymus and bursa of fabricius in broiler chickens

Aflatoxin B1 is known as a mycotoxin that develops various health problems of animals, the effects of AFB1 on thymus and bursa of Fabricius in chickens are not clear. The objective of this study was to investigate the apoptosis of thymus and bursa of Fabricius in broilers fed with AFB1 . Two hundred Avian broilers were randomly divided into four groups of 50 each, namely control group and three AFB1 groups fed with 0.15 mg, 0.3 mg, and 0.6 mg AFB1 /kg diet, respectively. In this study, flow cytometer and immunohistochemical approaches were used to determine the percentage of apoptotic cells and the expression of Bax, Bcl-2, and Caspase-3. The results showed that consumption of AFB1 diets results in increased percentage of apoptotic cells and increased expression of Caspase-3 in both thymus and bursa of Fabricius. The expression of Bax was increased and the expression of Bcl-2 was decreased in the thymus, but no significant changes in Bax and Bcl-2 expression were observed in the bursa of Fabricius when broilers fed with AFB1 . These findings suggest that adverse effects of AFB1 on thymus and bursa of Fabricius in broilers were confirmed by increased apoptotic cells and abnormal expression of Caspase-3. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1113-1120, 2016.

Selenium Deficiency Mainly Influences Antioxidant Selenoproteins Expression in Broiler Immune Organs

Selenoprotein has many functions in chicken, and the expression of selenoproteins is closely associated with the selenium (Se) level. However, little is known about the expression patterns of selenoproteins in chicken immune organs. Here, we investigated the effect of dietary Se deficiency on the expressions of 23 selenoproteins in broiler immune organs. In this study, 150 broilers were randomly divided into two groups (75 chickens per group). The chickens were maintained either on a diet supplemented with Se through the addition of 0.2 mg/kg of Se (C group) via sodium selenite or on a Se-deficient granulated diet (L group) until the broilers exhibited an onset of exudative diathesis (ED). Following euthanasia, the samples from the immune tissues (including the spleen, thymus, and bursa of Fabricius) were quickly collected, and the messenger RNA (mRNA) expression levels of 23 selenoproteins were examined by real-time quantitative PCR and analyzed using principal component analysis. The results showed that Se deficiency decreased the mRNA levels of 23 selenoproteins in the thymus, spleen, and bursa of the Fabricius tissues of broiler chickens. Furthermore, we found that among 23 selenoproteins, the mRNA levels of Dio1 in the thymus, Txnrd2 in the spleen, and Txnrd3 in the bursa of Fabricius decreased significantly (90.9 %, 83.3 %, and 96.8 %, respectively). In addition, the principal component analysis (PCA) results suggested that Se deficiency mainly influenced the expression of antioxidative selenoproteins, especially glutathione peroxidases (Gpxs), thioredoxin reductases (Txnrds), and iodothyronine deiodinases (Dios) in chicken immune organs. The results of this study are valuable for understanding the relevance of selenoprotein activity in vivo.

Nickel Chloride (NiCl2) Induces Histopathological Lesions via Oxidative Damage in the Broiler's Bursa of Fabricius

The purpose of this study was to investigate the histopathological lesions, oxidative damage, changes of immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) contents in the bursa of Fabricius and serum immunoglobulins (IgG, IgM, IgA) induced by dietary nickel chloride (NiCl2). Two hundred and eighty-one-day-old broilers were randomly divided into four groups and fed on a control diet and three experimental diets supplemented with 300, 600, and 900 mg/kg of NiCl2 for 42 days. Lesions were observed in the NiCl2-treated groups. Histopathologically, lymphocytes were decreased in lymphoid follicles with thinner cortices and wider medullae. Concurrently, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and the ability to inhibit hydroxyl radical and glutathione (GSH) contents were significantly (p < 0.05 or p < 0.01) decreased, while malondialdehyde (MDA) contents were increased in the NiCl2-treated groups. The serum IgG, IgM, and bursa IgG and IgM contents were significantly (p < 0.05 or p < 0.01) lower in the NiCl2-treated groups than those in the control group. The above-mentioned results show that dietary NiCl2 in excess of 300 mg/kg can cause histopathological lesions via oxidative damage, which finally impairs the function of the bursa of Fabricius and reduces IgG and IgM contents of the serum and the bursa of Fabricius. The study is aimed to provide helpful materials for studies on Ni- or Ni compounds-induced B cell toxicity in both human and other animals in the future.

The Functions of Antioxidants and Heat Shock Proteins Are Altered in the Immune Organs of Selenium-Deficient Broiler Chickens

Despite increasing evidence indicating the essential involvement of selenium (Se) in the immune system, the effect of Se deficiency on the regulation of oxidative stress and heat shock proteins (Hsps) in broiler chickens is still unclear. In the present study, we established an exudative diathesis (ED) broiler chicken model caused by Se deficiency. We then analyzed histological observations and detected the expression levels of Hsps and antioxidant indexes in immune tissues. The antioxidant function declined remarkably, and most of the Hsp expression levels increased significantly in the spleen, thymus, and bursa of Fabricius of the broiler chicks with ED (except the messenger RNA (mRNA) levels of Hsp27, Hsp40, and Hsp70, which decreased in thymus tissues from the treatment groups); therefore, constitutive oxidation resistance and higher Hsps in broiler chicks with ED caused defects in immune organ morphology and function, as evidenced by abnormal histological structures: red pulp broadening and lymphocytes in the cortex and medulla of the thymic lobule decreased distinctly and distributed loosely. These results underscore the importance of Se in establishing an immune organ microenvironment conducive to normal function.

Direct antiapoptotic effects of growth hormone are mediated by PI3K/Akt pathway in the chicken bursa of Fabricius

Growth hormone (GH) is expressed in several extra-pituitary tissues, including the primary and secondary lymphoid organs of the immune system. In birds, GH mRNA and protein expression show a specific developmental distribution pattern in the bursa of Fabricius (BF), particularly in epithelial and B cells. Changes in the bursal concentration and distribution of locally produced GH during ontogeny suggest it is involved in B cell differentiation and maturation, as well as in a functional survival role in this organ, which may be mediated by paracrine/autocrine mechanisms. Here, we analyzed the anti-apoptotic effect of GH in BF and the intracellular signaling pathways involved in this activity. Also, we studied if this effect was exerted directly by GH or mediated indirectly by IGF-I. Bursal cell cultures showed an important loss of their viability after 4h of incubation and a significant increase in apoptosis. However, treatment with 10nM GH or 40 nM IGF-I significantly increased B cell viability (16.7 ± 0.67% and 13.4 ± 1.12%, respectively) when compared with the untreated controls. In addition, the presence of apoptotic bodies (TUNEL) dramatically decreased (5.5-fold) after GH and IGF-I treatments, whereas co-incubation with anti-GH or anti-IGF-I, respectively, blocked their anti-apoptotic effect. Likewise, both GH and IGF-I significantly inhibited caspase-3 activity (by 40 ± 2.0%) in these cultures. However, the use of anti-IGF-I could not reverse the GH anti-apoptotic effects, thus indicating that these were exerted directly. The addition of 100 nM wortmannin (a PI3K/Akt inhibitor) blocked the GH protective effects. Also, GH stimulated (3-fold) the phosphorylation of Akt in bursal cells, and adding wortmannin or an anti-GH antibody inhibited this effect. Furthermore, GH was capable to stimulate (7-fold) the expression of Bcl-2. Taken together, these results indicate that the direct anti-apoptotic activity of GH observed in the chicken bursal B cell cultures might be mediated through the PI3K/Akt pathway.

Novel Pathways Revealed in Bursa of Fabricius Transcriptome in Response to Extraintestinal Pathogenic Escherichia coli (ExPEC) Infection

Extraintestinal pathogenic Escherichia coli (ExPEC) has major negative impacts on human and animal health. Recent research suggests food-borne links between human and animal ExPEC diseases with particular concern for poultry contaminated with avian pathogenic E. coli (APEC), the avian ExPEC. APEC is also a very important animal pathogen, causing colibacillosis, one of the world’s most widespread bacterial diseases of poultry. Previous studies showed marked atrophy and lymphocytes depletion in the bursa during APEC infection. Thus, a more comprehensive understanding of the avian bursa response to APEC infection will facilitate genetic selection for disease resistance. Four-week-old commercial male broiler chickens were infected with APEC O1 or given saline as a control. Bursas were collected at 1 and 5 days post-infection (dpi). Based on lesion scores of liver, pericardium and air sacs, infected birds were classified as having mild or severe pathology, representing resistant and susceptible phenotypes, respectively. Twenty-two individual bursa RNA libraries were sequenced, each yielding an average of 27 million single-end, 100-bp reads. There were 2469 novel genes in the total of 16,603 detected. Large numbers of significantly differentially expressed (DE) genes were detected when comparing susceptible and resistant birds at 5 dpi, susceptible and non-infected birds at 5 dpi, and susceptible birds at 5 dpi and 1 dpi. The DE genes were associated with signal transduction, the immune response, cell growth and cell death pathways. These data provide considerable insight into potential mechanisms of resistance to ExPEC infection, thus paving the way to develop strategies for ExPEC prevention and treatment, as well as enhancing innate resistance by genetic selection in animals.

Selenoproteins and heat shock proteins play important roles in immunosuppression in the bursa of Fabricius of chickens with selenium deficiency

Selenium (Se) is necessary for the immune system in chicken and mediates its physiological functions through selenoproteins. Heat shock proteins (Hsps) are indispensable for maintaining normal cell function and for directing the immune response. The aim of the present study was to investigate the effects of Se deficiency on the messenger ribonucleic acid (mRNA) expression levels of selenoproteins and Hsps as well as immune functions in the chicken bursa of Fabricius. Two groups of chickens, namely the control and Se-deficient (L group) groups, were reared for 55 days. The chickens were offered a basal diet, which contained 0.15 mg Se/kg in the diet fed to the control group and 0.033 mg Se/kg in the diet fed to the L group. We performed real-time quantitative polymerase chain reaction to detect the mRNA expression levels of selenoproteins and Hsps on days 15, 25, 35, 45 and 55. Western blotting was used to determine the protein expression levels of Hsps on days 35, 45 and 55, and immune functions were assessed through an enzyme-linked immunosorbent assay on days 15, 35, and 55. The data showed that the mRNA expression levels of selenoproteins, such as Txnrd1, Txnrd2, Txnrd3, Dio1, Dio2, Dio3, GPx1, GPx2, GPx3 GPx4, Sepp1, Selo, Sel-15, Sepx1, Sels, Seli, Selu, Selh, and SPS2, were significantly lower (P < 0.05) in the L group compared with the control group. Additionally, the mRNA and protein expression levels of Hsps (Hsp27, Hsp40, Hsp60, Hsp70, and Hsp90) were also significantly higher (P < 0.05) in the L group. The expression levels of IL-2, IL-6, IL-8, IL-10, IL-17, IL-1β, IFN-α, IFN-β, and IFN-γ were significantly lower (P < 0.05) and TNF-α was significantly higher (P < 0.05) in the L group compared with the control group. Our results show that immunosuppression was accompanied by a downregulation of mRNA expression levels of selenoproteins and an upregulation of the Hsp mRNA expression levels. Thus, Se deficiency causes defects in the chicken bursa of Fabricius, and selenoproteins and Hsps play important roles in immunosuppression in the bursa of Fabricius of chickens with Se deficiency.

Hyperpigmentation Results in Aberrant Immune Development in Silky Fowl (Gallus gallus domesticus Brisson)

The Silky Fowl (SF) is known for its special phenotypes and atypical distribution of melanocytes among internal organs. Although the genes associated with melanocyte migration have been investigated substantially, there is little information on the postnatal distribution of melanocytes in inner organs and the effect of hyperpigmentation on the development of SF. Here, we analyzed melanocyte distribution in 26 tissues or organs on postnatal day 1 and weeks 2, 3, 4, 6, 10, and 23. Except for the liver, pancreas, pituitary gland, and adrenal gland, melanocytes were distributed throughout the body, primarily around blood vessels. Interaction between melanocytes and the tissue cells was observed, and melanin was transported by filopodia delivery through engulfed and internalized membrane-encapsulated melanosomes. SFs less than 10 weeks old have lower indices of spleen, thymus, and bursa of Fabricius than White Leghorns (WLs). The expression levels of interferon-γ and interlukin-4 genes in the spleen, and serum antibody levels against H5N1 and infectious bursal disease virus were lower in SF than in WL. We also found immune organ developmental difference between Black-boned and non-Black- boned chickens from SFs and WLs hybrid F2 population. However, degeneration of the thymus and bursa of Fabricius occurred later in SF than in WL after sexual maturity. Analysis of apoptotic cells and apoptosis-associated Bax and Bcl-2 proteins indicated that apoptosis is involved in degeneration of the thymus and bursa of Fabricius. Therefore, these results suggest that hyperpigmentation in SF may have a close relationship with immune development in SF, which can provide an important animal model to investigate the roles of melanocyte.

Bursal transcriptome of chickens protected by DNA vaccination versus those challenged with infectious bursal disease virus

Infectious bursal disease virus (IBDV) infection destroys the bursa of Fabricius, causing immunosuppression and rendering chickens susceptible to secondary bacterial or viral infections. IBDV large-segment-protein-expressing DNA has been shown to confer complete protection of chickens from infectious bursal disease (IBD). The purpose of the present study was to compare DNA-vaccinated chickens and unvaccinated chickens upon IBDV challenge by transcriptomic analysis of bursa regarding innate immunity, inflammation, immune cell regulation, apoptosis and glucose transport. One-day-old specific-pathogen-free chickens were vaccinated intramuscularly three times at weekly intervals with IBDV large-segment-protein-expressing DNA. Chickens were challenged orally with 8.2 × 10(2) times the egg infective dose (EID)50 of IBDV strain variant E (VE) one week after the last vaccination. Bursae collected at 0.5, 1, 3, 5, 7, and 10 days post-challenge (dpc) were subjected to real-time RT-PCR quantification of bursal transcripts related to innate immunity, inflammation, immune cell regulation, apoptosis and glucose transport. The expression levels of granzyme K and CD8 in DNA-vaccinated chickens were significantly (p < 0.05) higher than those in unvaccinated chickens upon IBDV challenge at 0.5 or 1 dpc. The expression levels of other genes involved in innate immunity, inflammation, immune cell regulation, apoptosis and glucose transport were not upregulated or downregulated in DNA-vaccinated chickens during IBDV challenge. Bursal transcripts related to innate immunity and inflammation, including TLR3, MDA5, IFN-α, IFN-β, IRF-1, IRF-10, IL-1β, IL-6, IL-8, iNOS, granzyme A, granzyme K and IL-10, were upregulated or significantly (p < 0.05) upregulated at 3 dpc and later in unvaccinated chickens challenged with IBDV. The expression levels of genes related to immune cell regulation, apoptosis and glucose transport, including CD4, CD8, IL-2, IFN-γ, IL-12(p40), IL-18, GM-CSF, GATA-3, p53, glucose transporter-2 and glucose transporter-3, were upregulated or significantly (p < 0.05) upregulated at 3 dpc and later in unvaccinated chickens challenged with IBDV. Taken together, the results indicate that the bursal transcriptome involved in innate immunity, inflammation, immune cell regulation, apoptosis and glucose transport, except for granzyme K and CD8, was not differentially expressed in DNA-vaccinated chickens protected from IBDV challenge.

Prediction of selenoprotein T structure and its response to selenium deficiency in chicken immune organs

Selenoprotein T (SelT) is associated with the regulation of calcium homeostasis and neuroendocrine secretion. SelT can also change cell adhesion and is involved in redox regulation and cell fixation. However, the structure and function of chicken SelT and its response to selenium (Se) remains unclear. In the present study, 150 1-day-old chickens were randomly divided into a low Se group (L group, fed a Se-deficient diet containing 0.020 mg/kg Se) and a control group (C group, fed a diet containing sodium selenite at 0.2 mg/kg Se). The immune organs (spleen, thymus, and bursa of Fabricius) were collected at 15, 25, 35, 45, and 55 days of age. We performed a sequence analysis and predicted the structure and function of SelT. We also investigated the effects of Se deficiency on the expression of SelT, selenophosphate synthetase-1 (SPS1), and selenocysteine synthase (SecS) using RT-PCR and the oxidative stress in the chicken immune organs. The data showed that the coding sequence (CDS) and deduced amino acid sequence of SelT were highly similar to those of 17 other animals. Se deficiency induced lower (P < 0.05) levels of SelT, SPS1, and SecS, reduced the catalase (CAT) activity, and increased the levels of hydrogen peroxide (H2O2) and hydroxyl radical (-OH) in immune organs. In conclusion, the CDS and deduced amino acid sequence of chicken SelT are highly homologous to those of various mammals. The redox function and response to the Se deficiency of chicken SelT may be conserved. A Se-deficient diet led to a decrease in SelT, SecS, and SPS1 and induced oxidative stress in the chicken immune organs. To our knowledge, this is the first report of predictions of chicken SelT structure and function. The present study demonstrated the relationship between the selenoprotein synthases (SPS1, SecS) and SelT expression in the chicken immune organs and further confirmed oxidative stress caused by Se deficiency. Thus, the information presented in this study is helpful to understand chicken SelT structure and function. Meanwhile, the present research also confirmed the negative effects of Se deficiency on chicken immune organs.

Effect of sonication on B cell development and immunomodulatory functions of Bursa of Fabricius

A study was initiated with the objective of evaluating the effects of sonication treatment on important quality parameters of extract of Bursa of Fabricius. Sonication of extract was done (frequency 20 kHz and various amplitude levels) at 0 °C for 10 min, 30 min, 50 min, respectively. As results, the yield of bursa peptides significantly increased (p<0.05). Then we found sonicated bursa extract promoted the content of bursin and the CFU pre-B formation, exerted immunomodulatory function on antigen-specific immune responses in C57/BL6 mice immunized with inactivated Japanese encephalitis b virus (JEV) vaccine, including enhancing JEV-specific antibody and cytokine production, T-cell immunophenotyping and lymphocyte proliferation. Findings of the present study suggested the sonication treatment of Bursa of Fabricius could improve the yield as well as the quality of bursa peptides, indicating that sonication is effective in processing of bursa extract and could be a potential process for future immuno-pharmacological use.

Expression and function of chicken bursal growth hormone (GH)

Growth hormone (GH) has several effects on the immune system. Our group has shown that GH is produced in the chicken bursa of Fabricius (BF) where it may act as an autocrine/paracrine modulator that participates in B-cell differentiation and maturation. The time course of GH mRNA and protein expression in the BF suggests that GH may be involved in development and involution of the BF, since GH is known to be present mainly in B lymphocytes and epithelial cells. In addition, as GH is anti-apoptotic in other tissues, we assessed the possibility that GH promotes cell survival in the BF. This work focused on determining the mechanism by which GH can inhibit apoptosis of B cells and if the PI3K/Akt pathway is activated. Bursal cell cultures were treated with a range of GH concentrations (0.1-100nM). The addition of 10nM GH significantly increased viability (16.7±0.6%) compared with the control and decreased caspase-3 activity to 40.6±6.5% of the control. Together, these data indicate that GH is produced locally in the BF and that the presence of exogenous GH in B cell cultures has antiapoptotic effects and increases B cell survival, probably through the PI3k/Akt pathway.

Comparison of immunomodulatory functions of three peptides from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the acknowledged central humoral immune organ unique to birds which plays important roles in B cell development and antibody production. Little information on immunomodulatory functions of BF is reported, except for several reported active bursal-derived peptides. Three peptides were identified and characterized from BF through RP-HPLC and MADIL-TOF methods. They are named as bursal peptide (BP)-I, BP-II, BP-III. These peptides promoted CFU pre-B formation and decreased PU.1 expression. The different immunomodulatory activities of these three bursal peptides on antibody and cytokine productions were verified by the immunization comparative experiment. The results showed the three bursal peptides enhanced AIV-specific antibody and cytokine production, T-cell immunophenotyping at reachable concentrations. These results indicate the important orientations for the comprehensive understanding of the humoral central immune system, and provide a novel insight on new experimental reagents for immuno-adjuvant or immunopharmacological.

Expression of chicken DEC205 reflects the unique structure and function of the avian immune system

The generation of appropriate adaptive immune responses relies critically on dendritic cells, about which relatively little is known in chickens, a vital livestock species, in comparison with man and mouse. We cloned and sequenced chicken DEC205 cDNA and used this knowledge to produce quantitative PCR assays and monoclonal antibodies to study expression of DEC205 as well as CD83. The gene structure of DEC205 was identical to those of other species. Transcripts of both genes were found at higher levels in lymphoid tissues and the expression of DEC205 in normal birds had a characteristic distribution in the primary lymphoid organs. In spleen, DEC205 was seen on cells ideally located to trap antigen. In thymus it was found on cells thought to participate in the education of T cells, and in the bursa on cells that may be involved in presentation of antigen to B cells and regulation of B cell migration. The expression of DEC205 on cells other than antigen presenting cells (APC) is also described. Isolated splenocytes strongly expressing DEC205 but not the KUL01 antigen have morphology similar to mammalian dendritic cells and the distinct expression of DEC205 within the avian-specific Bursa of Fabricius alludes to a unique function in this organ of B cell diversification.

Isolation, modulatory functions on murine B cell development and antigen-specific immune responses of BP11, a novel peptide from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the central humoral immune organ unique to birds which plays important roles in B lymphocyte differentiation. Here, a new bursal peptide (BP11) with the amino acid sequence DVAGKLPDNRT was identified and characterized from BF. It was proved that BP11 promoted CFU pre-B formation, and regulated B cell differentiation, including increase the percentage of immature and mature B cells in BM cells co-cultured with IL-7. BP11 also exerted immunomodulatory function on antigen-specific immune responses in BALB/c mice immunized with inactivated influence virus (AIV, H9N2 subtype) vaccine, including enhancing AIV-specific antibody and cytokine production. Furthermore, it was noteworthy that BP11 stimulated antibody productions and potentiates the Th1 and Th2-type immune responses in dose-dependent manner in chicken. These results suggested that BP11 might be highly relevant for the development of avian immune system.

Dietary vanadium induces lymphocyte apoptosis in the bursa of Fabricius of broilers

The purpose of this 42-day study was to investigate the apoptosis in the bursa of Fabricius induced by different levels of dietary vanadium. A total of 420 1-day-old avian broilers were divided into 6 groups in which there were 7 replicates in each group and 10 broilers in each replicate and fed on a corn-soybean basal diet as control diet (vanadium 0.073 mg/kg) or the same diet amended to contain 5, 15, 30, 45, and 60 mg/kg vanadium supplied as ammonium metavanadate (NH(4)VO(3)). Ultrastructurally, mitochondrial injury and increased numbers of apoptotic cells with condensed nuclei were observed in the 30, 45, and 60 mg/kg groups. As measured by flow cytometry, the percentages of apoptotic lymphocytes were significantly increased in the 15-, 30-, 45-, and 60-mg/kg groups when compared with those of control group. Meanwhile, the terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end-labeling assay showed that there were increased numbers of apoptotic cells in the 30-, 45-, and 60-mg/kg groups. Immunohistochemical tests showed increased numbers of positive cells under Bax and caspase-3 protein detection and decreased Bcl-2 protein in the 15-, 30-, 45-, and 60-mg/kg groups. The vanadium content of the bursa was found to be significantly increased in the 30-, 45-, and 60-mg/kg groups. These results suggested that dietary vanadium in excess of 15 mg/kg could cause lymphocyte apoptosis in the bursa of Fabricius and impact humoral immunity in broilers. Lymphocyte apoptosis in the bursa induced by high levels of dietary vanadium is associated with mitochondrial injury and changes in levels of apoptogenic proteins, such as Bcl-2, Bax, and caspase-3.

Effects of dietary selenium on selenoprotein W gene expression in the chicken immune organs

Selenoprotein W (SelW) is expressed in the immune systems of mammals. However, its pattern of expression in the immune organs of birds is still unclear. To investigate the distribution of SelW and effects of dietary Se levels on the SelW mRNA expression in the immune organs of birds, 1-day-old male chickens were fed either a commercial diet or an Se-supplemented diet containing 0.601, 1.058, 1.514, or 2.427 mg Se per kilogram, and 1.0, 2.0, 3.0 or 5.0 mg sodium selenite per kilogram for 90 days. The immune organs (spleen, thymus, and bursa of Fabricius) were collected and examined for Se content and SelW mRNA levels. The mRNA expression of SelW was detected in all the tissues. Although Se content was the highest in the spleen, the remarkable stability of the SelW mRNA level was observed in this organ during different times of dietary Se supplementation. Se-supplemented diet can make the SelW expression levels higher within a certain range in thymus and bursa of Fabricius. The present study demonstrates that SelW is widely expressed in immune organs of birds and that Se-supplementation of the feed increases SelW expression in the thymus and the bursa of Fabricius.

Toxic effects of dietary methylmercury on immune function and hematology in American kestrels (Falco sparverius)

Fifty-nine adult male American kestrels (Falco sparverius) were assigned to one of three diet formulations including 0 (control), 0.6, and 3.9 µg/g (dry wt) methylmercury (MeHg). Kestrels received their diets daily for 13 weeks to assess the effects of dietary MeHg on immunocompetence. Immunotoxic endpoints included assessment of cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and primary and secondary antibody-mediated immune responses (IR) via the sheep red blood cell (SRBC) hemagglutination assay. Select hematology and histology parameters were evaluated to corroborate the results of functional assays and to assess immunosuppression of T and B cell-dependent components in spleen tissue. Kestrels in the 0.6 and 3.9 µg/g MeHg groups exhibited suppression of CMI, including lower PHA stimulation indexes (p = 0.019) and a 42 to 45% depletion of T cell-dependent splenic lymphoid tissue (p = 0.006). Kestrels in the 0.6 µg/g group exhibited suppression of the primary IR to SRBCs (p = 0.014). MeHg did not have a noticeable effect on the secondary IR (p = 0.166). Elevation of absolute heterophil counts (p < 0.001), the heterophil to lymphocyte ratio (p < 0.001), and total white blood cell counts (p = 0.003) was apparent in the 3.9 µg/g group at week 12. Heterophilia, or the excess of heterophils in peripheral blood above normal ranges, was apparent in seven of 17 (41%) kestrels in the 3.9 µg/g group and was indicative of an acute inflammatory response or physiological stress. This study revealed that adult kestrels were more sensitive to immunotoxic effects of MeHg at environmentally relevant dietary concentrations than they were to reproductive effects as previously reported.

Isolation, antiproliferation on tumor cell and immunomodulatory activity of BSP-I, a novel bursal peptide from chicken humoral immune system

The bursa of Fabricius (BF) is acknowledged as central humoral immune organ unique to birds. Our purpose was to identify the potential function of a novel bursal-derived bioactive peptide. A bursal septpeptide (BSP-I), EPASGMM, first isolated from BF, reduced MCF and Hela tumor cells proliferation, and enhanced antitumor factor p53 luciferase activity and protein expression. Further, we found the significantly immune inducing function of BSP-I on antigen-specific immune response in BALB/c mice intraperitoneally immunized with inactivated avian influence virus (AIV, H(9)N(2) subtype) vaccine, including of enhancing the antibody (IgG, the isotypes IgG1 and IgG2a) production, and stimulating cytokines IL-4 and IFN-γ level, and inducing T cell immunophenotyping and lymphocyte proliferation. These results suggested that as the bioactive peptide from avian humoral immune system, various biological function of BSP-I may have far-reaching implication on immune system significance, which might provide novel insight on linking between humoral immune system and development of effective immunotherapeutic strategies for treating human cancers diseases.

Expression of perforin-granzyme pathway genes in the bursa of infectious bursal disease virus-infected chickens

Infectious bursal disease (IBD) is an economically important immunosuppressive disease of chickens. The IBD virus (IBDV) actively replicates in B cells and causes severe bursal damage. Generally, T cells are refractory to infection with IBDV but are known to promote virus clearance. However, the mechanisms of T cell mediated viral clearance are not well understood. In this study, we evaluated the molecular mechanisms of cytotoxic T cell responses in the pathogenesis of IBD in chickens. Infection of chickens with IBDV was accompanied by the infiltration of CD4(+) and CD8(+) T cells in the bursa. There was an upregulation in the gene expression of important cytolytic molecules; perforin (PFN), granzyme-A (Gzm-A), DNA repair and apoptotic proteins; high mobility proteins group (HMG) and poly (ADP-ribose) polymerase (PARP) in the bursa of Fabricius (BF) whereas expression of NK (natural killer) lysin was downregulated. Importantly, PFN producing CD4(+) and CD8(+) T cells were also detected in the bursa of IBDV-infected chickens by immunohistochemistry. The Th1 cytokines, IL-2 and IFN-γ expression was also strongly upregulated, suggesting the activation of T cells. The findings of this study highlight the mechanisms of IBD pathogenesis and the role of cytotoxic T cells in the clearance of virus-infected cells.

[Screening proteins interacting with infectious bursa disease virus Gt VP2 from cDNA library of B lymphoid cells of the bursa of Fabricius]

To screen the interactive proteins with IBDV Gt VP2 protein from cDNA library of B Lymphoid cells of the bursa of Fabricius. The expression cDNA library plasmids was transformed to the yeast competent cells, which have the bait plasmid-Gt VP2. After testing for growth in synthetic complete medium lacking histidine and uracil and for production of beta-galactosidase (X-gal), we obtained 16 positive clones. We searched the gene sequences of positive clones in the NCBI website. The blast results showed that five positive clones were the gallus sequences. They were Gallus gallus breed mitochondrial DNA, O_G1cNAc transferase, Tumor protein p53 binding protein, Stathmin and Chondroitin sulfate Ga1NAcT-2, respectively. This study is helpful for the further identifying the receptors of IBDV in B Lymphoid cells of the bursa of Fabricius.

Immune growth hormone (GH): localization of GH and GH mRNA in the bursa of Fabricius

Expression of growth hormone (GH) and GH receptor (GHR) genes in the bursa of Fabricius of chickens suggests that it is an autocrine/paracrine site of GH production and action. The cellular localization of GH and GH mRNA within the bursa was the focus of this study. GH mRNA was expressed mainly in the cortex, comprised of lymphocyte progenitor cells, but was lacking in the medulla where lymphocytes mature. In contrast, more GH immunoreactivity (GH-IR) was present in the medulla than in the cortex. In non-stromal tissues, GH-IR and GH mRNA were primarily in lymphocytes, and also in macrophage-like cells and secretory dendritic cells. In stromal tissues, GH mRNA, GH and GHR were expressed in cells near the connective tissue (CT) between follicles and below the outer serosa. In contrast, GH (but not GH mRNA or GHR), was present in cells of the interfollicular epithelium (IFE), the follicle-associated epithelium (FAE) and the interstitial corticoepithelium. This mismatch may reflect dynamic temporal changes in GH translation. Co-expression of GHR-IR, GH-IR, GH mRNA and IgG was found in immature lymphoid cells near the cortex and in IgG-IR CT cells, suggesting an autocrine/paracrine role for bursal GH in B-cell differentiation.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) predominantly induce Th1-type immune response in neonatal chicks

Earlier, we demonstrated that intramuscular administration of oligodeoxynucleotides containing CpG motifs (CpG-ODN) induces protection in neonatal chicks against a lethal challenge of Escherichia coli. However, the mechanism of induction of the protection was not clear. In an attempt to elucidate the mechanism of induced protection, we determined the kinetics of expression of cytokines/chemokines in the spleen and bursa of Fabricius of newly hatched chicks that had received intramuscular administration of CpG-ODN or non-CpG ODN compared to saline-treated controls. SyBr green, real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis of the RNA demonstrated increased expression of IL-1beta, IL-6, IL-8, IL-10, IL-18, IFN-gamma and MIP-3alpha mRNAs in the spleen and; IL-10 and IFN-alpha in bursa of Fabricious of chicks that had received CpG-ODN. However, non-CpG ODN failed to induce any of the cytokine. The increased level of IL-18 and IFN-gamma but not IL-4 mRNA suggests that the administration of CpG-ODN elicits a Th1 biased immune response, which may be important in inducing protection against infections in neonatal chicks. To our knowledge, this is the first report evaluating the induction of cytokines/chemokines in neonatal chicks following administration of CpG-ODN.

Effects of corticosterone treatment on growth, development, and the corticosterone response to handling in young Japanese quail (Coturnix coturnix japonica)

Corticosterone, a glucocorticoid secreted during stress responses, has a range of actions that help birds respond to stressors. Although effects of corticosterone treatment have been described in several avian species, the impacts of defined increases in plasma corticosterone on early development and on corticosterone stress responses are little known. These issues were addressed by providing quail with different doses of corticosterone in drinking water from days 8 to 38 post-hatch. The corticosterone dose consumed by each bird during treatment days 15-30 was calculated by measuring water intake. The corticosterone dose was inversely, but weakly, correlated with weights of the bursa, thymus, spleen, liver, testes, oviduct, muscle, and body, and positively correlated with peritoneal fat deposition. When birds were divided into groups based on their corticosterone intake, weights of the spleen, thymus, bursa, muscle, testes, and oviduct were significantly reduced in birds receiving the highest doses; with the exception of muscle, similar reductions were also observed in birds receiving medium doses, and thymic growth was inhibited in birds receiving low doses. The acute corticosterone stress response was measured by handling birds for 15 min. Plasma corticosterone was transiently increased at 15 min in control birds in response to the handling stressor. Some birds consuming low doses of corticosterone had corticosterone responses similar to control birds. Initial corticosterone concentrations were elevated in birds consuming higher doses of corticosterone. Plasma corticosterone in these birds decreased from 0 to 15 min, then increased from 15 to 30 min. The initial decrease could be due to corticosterone clearance, whilst the increase could indicate that the birds had a greater response than control birds to isolation as a stressor. Corticosterone treatment may have reduced the strength of corticosterone negative feedback within the hypothalamo-pituitary-adrenal axis. The results indicate that individuals and organs differ in their sensitivity to corticosterone. Moreover, elevated plasma corticosterone may disrupt the acute corticosterone stress response, and may thus reduce the ability of birds to cope with stressors.

Unique features and distribution of the chicken CD83+ cell

The central importance of dendritic cells (DC) in both innate and acquired immunity is well recognized in the mammalian immune system. By contrast DC have yet to be characterized in avian species despite the fact that avian species such as the chicken have a well-developed immune system. CD83 has proven to be an excellent marker for DC in human and murine immune systems. In this study we identify chicken CD83 (chCD83) as the avian equivalent of the human and murine DC marker CD83. We demonstrate for the first time that unlike human and murine CD83, chCD83 is uniquely expressed in the B cell areas of secondary lymphoid organs and in organs with no human or murine equivalent such as the bursa and Harderian gland. Furthermore through multicolor immunofluorescence, we identify chCD83(+) populations that have unique attributes akin to both DC and follicular DC. These attributes include colocalization with B cell microenvironments, MHC class II expression, dendritic morphology, and distribution throughout peripheral and lymphoid tissues.

Energy metabolism in developing chicken lymphocytes is altered during the embryonic to posthatch transition

Adequate energy status in lymphocytes is vital for their development. The ability of developing chicken lymphocytes to acquire and metabolize energy substrates was determined during embryonic days (e) and neonatal days (d) of life when primary-energy substrate metabolism is altered at the whole-animal level. In 3 experiments, bursacytes and thymocytes were isolated on e17, e20, d1, d3, d7, or d14 to analyze markers associated with glucose, glutamine, and lipid metabolism. Bursacyte glucose transporter-3 (Glut-3) mRNA abundance increased from d1 to d14 and hexokinase-1 (HK-1) mRNA abundance was maximum on e20 (P<0.05). Thymocyte Glut-1, Glut-3, and HK-1 mRNA abundance increased from e17 to d14 (P<0.05). HK enzyme activity increased from e20 to d3 in bursacytes and d3 to d7 in thymocytes (P<0.05). Glucose uptake by bursacytes and thymocytes was greater on d14 compared to d1 and d7 (P<0.05). Bursacyte and thymocyte sodium coupled neutral amino acid transporter-2 and glutaminase (GA) mRNA abundance increased from e20 to d7 (P<0.05). GA enzyme activity increased from e20 to d7 in bursacytes (P<0.05) and did not change in thymocytes. Carnitine palmitoyl transferase enzyme activity did not change over time in either cell type. These studies suggest that developing B and T lymphocytes adapt their metabolism during the first 2 wk after hatch. Developing lymphocytes increase glucose metabolism with no change in fatty acid metabolism and bursacytes, but not thymocytes, increase glutamine metabolism. Understanding the factors that regulate lymphocyte development in neonatal chicks may help promote their adaptive immune responses to pathogens in early life.

Osteoblasts support B-lymphocyte commitment and differentiation from hematopoietic stem cells

Early B lymphopoiesis in mammals is induced within the bone marrow (BM) microenvironment, but which cells constitute this niche is not known. Previous studies had shown that osteoblasts (OBs) support hematopoietic stem cell (HSC) proliferation and myeloid differentiation. We now find that purified primary murine OBs also support the differentiation of primitive hematopoietic stem cells through lymphoid commitment and subsequent differentiation to all stages of B-cell precursors and mature B cells. Lin(-)Sca-1(+)Rag-2(-) BM cell differentiation to B cells requires their attachment to OBs in vitro, and this developmental process is mediated via VCAM-1, SDF-1, and IL-7 signaling induced by parathyroid hormone (PTH). Addition of cytokines produced by nonosteoblastic stromal cells (c-Kit ligand, IL-6, and IL-3) shifted the cultures toward myelopoiesis. Confirming the role of OBs in B lymphopoiesis, we found that selective elimination of osteoblasts in Col2.3Delta-TK transgenic mice severely depleted pre-pro-B and pro-B cells from BM, preceding any decline in HSCs. Taken together, these results demonstrate that osteoblasts are both necessary and sufficient for murine B-cell commitment and maturation, and thereby constitute the cellular homolog of the avian bursa of Fabricius.

Maternal dietary n-3 fatty acids alter immune cell fatty acid composition and leukotriene production in growing chicks

The effect of feeding different amounts of n-6 and n-3 fatty acids (FA) to hens on immune tissue FA composition and leukotriene production of hatched chicks was investigated. Hens were fed diets supplemented with either 3.0% sunflower oil (Diet I), 1.5% sunflower+1.5% fish oil (Diet II), or 3.0% fish oil (Diet III) for 46 days. The hatched chicks were fed a diet containing C18:3n-3, but devoid of longer chain n-6 and n-3 FA, for 21 days. Spleen docosahexaenoic acid (DHA) content was higher in chicks from hens fed Diet III (P<0.05). The bursa content of arachidonic acid was lower in chicks hatched from hens fed Diet III (P<0.05), and the ratio of n-6 to n-3 FA was significantly higher in bursa of chicks hatched to hens fed Diet I (P<0.05). Eicosapentaenoic acid (EPA) and DHA contents were higher in bursa of chicks hatched from hens fed Diet III (P<0.05). Thrombocytes from chicks hatched to hens fed Diet III produced the most leukotriene B(5) (LTB(5)). The ratio of LTB(5) to LTB(4) concentrations was also highest (P<0.05) in chicks hatched to hens fed Diet III. These results indicate that modulating maternal dietary n-6 and n-3 FA may alter leukotriene production in chicks, which could lead to less inflammatory-related disorders in poultry.