CD4, CD8 and TCR defined T-cell subsets in thymus and spleen of 2- and 7-week old commercial broiler chickens

Spontaneous immunological activities in the target tissue of vitiligo-prone Smyth and vitiligo-susceptible Brown lines of chicken

Introduction

Vitiligo is an acquired de-pigmentation disorder characterized by the post-natal loss of epidermal melanocytes (pigment-producing cells) resulting in the appearance of white patches in the skin. The Smyth chicken is the only model for vitiligo that shares all the characteristics of the human condition including: spontaneous post-natal loss of epidermal melanocytes, interactions between genetic, environmental and immunological factors, and associations with other autoimmune diseases. In addition, an avian model for vitiligo has the added benefit of an easily accessible target tissue (a growing feather) that allows for the repeated sampling of an individual and thus the continuous monitoring of local immune responses over time.

Methods

Using a combination of flow cytometry and gene expression analyses, we sought to gain a comprehensive understanding of the initiating events leading to expression of vitiligo in growing feathers by monitoring the infiltration of leukocytes and concurrent immunological activities in the target tissue beginning prior to visual onset and continuing throughout disease development.

Results

Here, we document a sequence of immunologically significant events, including characteristic rises in infiltrating B and αβ T cells as well as evidence of active leukocyte recruitment and cell-mediated immune activities (CCL19, IFNG, GZMA) leading up to visual vitiligo onset. Examination of growing feathers from vitiligo-susceptible Brown line chickens revealed anti-inflammatory immune activities which may be responsible for preventing vitiligo (IL10, CTLA4, FOXP3). Furthermore, we detected positive correlations between infiltrating T cells and changes in their T cell receptor diversity supporting a T cell-specific immune response.

Conclusion

Collectively, these results further support the notion of cell-mediated immune destruction of epidermal melanocytes in the pulp of growing feathers and open new avenues of study in the vitiligo-prone Smyth and vitiligo-susceptible Brown line chickens.

In ovo HVT vaccination enhances cellular responses at hatch and addition of poly I:C offers minimal adjuvant effects

In ovo vaccination with herpesvirus of turkey (HVT) hastens immunocompetence in chickens and the recommended dose (RD) of 6080 plaque-forming-units (PFU) offers the most optimal effects. In previous studies conducted in egg-type chickens, in ovo vaccination with HVT enhanced lymphoproliferation, wing-web thickness with phytohemagglutinin-L (PHA-L), and increased spleen and lung interferon-gamma(IFN-γ) andToll-like receptor 3 (TLR3) transcripts. Here, we evaluated the cellular mechanisms by which HVT-RD can hasten immunocompetence in one-day-old meat-type chickens, and also determined if HVT adjuvantation with a TLR3 agonist, polyinosinic-polycytidylic acid (poly(I:C)), could enhance vaccine-induced responses and provide dose-sparing effects. Compared to sham-inoculated chickens, HVT-RD significantly increased transcription of splenic TLR3 and IFN γ receptor 2 (R2), and lung IFN γ R2, while the splenic IL-13 transcription was found decreased. Additionally, these birds showed increased wing-web thickness following PHA-L inoculation. The thickness was due to an innate inflammatory cell population, CD3⁺ T cells, and edema. In another experiment, HVT-1/2 (3040 PFU) supplemented with 50 μg poly(I:C) [HVT-1/2 + poly(I:C)] was administered in ovo and immune responses were compared with those produced by HVT-RD, HVT-1/2, 50 μg poly(I:C), and sham-inoculated. Immunophenotyping of splenocytes showed HVT-RD induced a significantly higher frequency of CD4⁺, CD4⁺MHC-II⁺, CD8⁺CD44⁺, and CD4⁺CD28⁺ T cells compared to sham-inoculated chickens, and CD8⁺MHC-II⁺, CD4⁺CD8⁺, CD4⁺CD8⁺CD28⁺, and CD4⁺CD8⁺CD44⁺ T cells compared to all groups. Treatment groups, except HVT-1/2 + poly(I:C), had significantly higher frequencies of γδ T cells and all groups induced significantly higher frequencies of activated monocytes/macrophages, compared to sham-inoculated chickens. Poly(I:C)-induced dose-sparing effect was only observed in the frequency of activated monocytes/macrophages. No differences in the humoral responses were observed. Collectively, HVT-RD downregulated IL-13 transcripts (Th2 immune response) and had strong immunopotentiation effects on innate immune responses and the activation of T cells. However addition of poly(I:C) offered a minimal adjuvant/dose-sparing effect.

Effect of Hydrolyzed Gallotannin on Growth Performance, Immune Function, and Antioxidant Capacity of Yellow-Feather Broilers

Tannins were traditionally considered as anti-nutritional factors in poultry production. Recent studies found that the addition of hydrolyzed gallotannin (HGT) could improve animal health; however, the proper dosage of HGT in chickens' diet is still unknown. Hence, our study aims to recommend its optimal dose by exploring the effects of HGT from Chinese gallnuts on the growth performance, immune function, and antioxidant capacity of yellow-feather broilers. A total of 288 male yellow-feather broilers (34.10 ± 0.08 g) were randomly allocated to four diet treatments, the basal diet with 0 (CON), 150, 300, and 450 mg/kg HGT for 63 days, respectively, with six replications per treatment and 12 birds per replication. The growth performance, slaughter performance, immune organ index, liver antioxidant-related indicators, and serum immune-related factors were evaluated. Results show that HGT supplementation did not influence the growth performance of broilers, but the diets supplemented with 300 and 450 mg/kg HGT increased the semi-eviscerated rate. Furthermore, HGT increased the content of liver T-AOC and the ratio of GSH/GSSG, which can protect against oxidative damage of birds. Additionally, supplementing HGT raised the contents of serum IL-10, IL-4, IL-6, IgA, and IgM. In conclusion, diet supplemented with 450 mg/kg HGT may be the optimal to the health of yellow-feather broilers on the whole.

Basal diet composition contributes to differential performance, intestinal health, and immunological responses to a microalgae-based feed ingredient in broiler chickens

Novel feed ingredients may improve poultry health, but functionality of these ingredients may vary across basal diet formulations. This study evaluated a proprietary algae ingredient's effects on broiler performance, intestinal health, systemic immunity, and metabolic/immune kinotypes between corn- or wheat-based diets. Ross 308 broilers were housed in 80 floor pens (14 birds/pen) and assigned to 1 of 4 corn or wheat-based diets ± 0.175% algae ingredient for 42 d. At the end of each 14 d starter, grower, and finisher period, 10 birds/treatment were euthanized for tissue collection to assess intestinal histomorphology, systemic immune cell populations by flow cytometry and kinotypes by peptide arrays. On d 28 and 29, forty-three birds/treatment underwent a 12 h feed restriction challenge followed by a fluorescein isothiocyanate-dextran intestinal permeability assay. For the entire 42 d study, wheat-based diets improved feed conversion rate (FCR) by 5 points compared to corn-based diets (P < 0.0001). Performance benefits related to algae inclusion were diet dependent, with algae inclusion improving 42 d FCR by 6 points only in corn-based diets (P = 0.006). Birds fed wheat-based diets had reduced splenic monocyte/macrophage, CD1.1⁺, and T cell populations in the first 14 d (P < 0.0001) and reduced serum fluorescence on d 28/29 (P = 0.0002). Algae inclusion in the corn-based diet increased villus height in the duodenum on d 28 and jejunum on d 42, while reducing splenic CD3⁺CD8α⁺ cytotoxic T cells 13.4 to 27.5% compared to the corn-based control at the same timepoints (P < 0.0001). Kinome results showed a significant innate immune toll-like receptor (TLR) response via MyD88 at d 14 in the small intestine of birds fed corn-based diets with algae that shifted to a more growth factor and adaptive immune-oriented response by d 42. Concurrent with immune changes, signaling changes indicative of lipid metabolism in the small intestine, ceca, and liver were seen in birds fed the corn-based diet with algae. The observed differential responses to basal diet composition and algae inclusion emphasize the need to comparatively evaluate feed ingredients in various diet formulations.

Effect of Curcumin as Feed Supplement on Immune Response and Pathological Changes of Broilers Exposed to Aflatoxin B1

In this study, we examined the protective effects of curcumin against the AFB1-induced immune response of and pathological changes in broilers. Histopathology examinations showed that at day 28, AFB1 (5 mg/kg) exposure leads to severe histological changes in the spleen, thymus and bursa of Fabricius with a decrease in the number and karyoplasmic area ratio of plasma cells. Curcumin alleviated the AFB1-induced immune organs’ damage as well as the changes in plasma cells in a dose-dependent manner. RT-PCR data showed that AFB1 significantly downregulated the IL-2 and IFN-γ mRNA expression levels in the thymus, spleen and bursa of Fabricius. However, curcumin supplementation improved the AFB1-induced immune organs’ damage via upregulated cytokines’ expression. Intriguingly, similar trends were noticed in abnormal morphological changes and the immune response at day 35 after the withdrawal of AFB1 and curcumin from the diet, suggesting the protective effects and immunomodulatory function against AFB1 in broilers. The current study provides a scientific experimental basis for the application of curcumin as a therapeutic drug or additive in animal husbandry productive practice.

Trypanosoma cruzi, beyond the dogma of non-infection in birds

Trypanosoma cruzi is a protozoan parasite responsible for Chagas disease affecting seven million people. The disease cycle is maintained between Triatominae insects and Mammalia hosts; a refractory effect against infection was noted in birds, but only verified in poultry. This paper presents a new host record for T. cruzi, the American barn-owl (Tyto furcata). Trypanosoma cruzi DTU II molecular evidence was found in heart, intestine, liver, and breast suggesting an established chronic infection based on the parasite DNA presence in multiple organs but absent in spleen, as in the murine model and chronically infected raccoons (Procyon lotor). For birds, the parasite rejection was explained based on the complement and high body temperature, but these mechanisms vary greatly among the members of the avian class. Therefore, there is a need to investigate whether more bird species can become infected, and if T. furcata has a role in disseminating, transmitting and/or maintaining the parasite.

Effects of age on immune function in broiler chickens

BACKGROUND

There are many diseases in poultry, many of which are caused by poor immune function. It is not clear how cytokines and various immune cell functions change with age in modern broilers. The purpose of this study was to explore the patterns of development of the immunity of the broiler chickens in cage.

RESULTS

The results showed that there were 3 development patterns of immunity in the broiler chickens. The first pattern was Down-Up. Cytokines and some immune indicators first decreased and then increased, and the lowest levels of immunity basically occurred from d 6 to 13. The second pattern was Up-Down, and from d 30 to 34, the highest levels of non-specific cellular immunity components, such as the peripheral blood mononuclear macrophage ratio, specific cellular immunity components, such as the peripheral blood helper T (Th) cell ratio and T cell and B cell proliferation activity, and mucosal immunity components, such as the ileal CD4, TGF-β1 and IgA mRNA levels, were observed. The third pattern was Up-Up, and the levels of the non-specific cellular immunity components, such as the serum nitric oxide (NO), C3 and C4 levels, the specific cellular immunity components, such as the spleen index, peripheral blood IL-2, IFN-γ/IL-4, cytotoxic T (Tc) cell ratio, and splenic NF-κB mRNA levels, the humoral immunity components, such as the serum IgG level, the mucosal immunity components, such as the ileal MHC-II, CD3d, TCRβ subunit, TCRζ subunit, IFN-γ, pIgR mRNA and ileal mucosa sIgA levels, were continuing to increase from d 1 to 34.

CONCLUSIONS

It could be concluded that the immune system and its function have not developed well in the broiler chickens d 6 to 13 and that the immune system does not mature until d 30 to 34 in the broiler chickens in cages. It is necessary to enhance the immune function of the broiler chickens through nutritional measures from d 1 to 30.

The Combination of CD8αα and Peptide-MHC-I in a Face-to-Face Mode Promotes Chicken γδT Cells Response

The CD8αα homodimer is crucial to both thymic T cell selection and the antigen recognition of cytotoxic T cells. The CD8-pMHC-I interaction can enhance CTL immunity via stabilizing the TCR-pMHC-I interaction and optimizing the cross-reactivity and Ag sensitivity of CD8⁺ T cells at various stages of development. To date, only human and mouse CD8-pMHC-I complexes have been determined. Here, we resolved the pBF2*1501 complex and the cCD8αα/pBF2*1501 and cCD8αα/pBF2*0401 complexes in nonmammals for the first time. Remarkably, cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 complex both exhibited two binding modes, including an “antibody-like” mode similar to that of the known mammal CD8/pMHC-I complexes and a “face-to-face” mode that has been observed only in chickens to date. Compared to the “antibody-like” mode, the “face-to-face” binding mode changes the binding orientation of the cCD8αα homodimer to pMHC-I, which might facilitate abundant γδT cells to bind diverse peptides presented by limited BF2 alleles in chicken. Moreover, the forces involving in the interaction of cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 are different in this two binding model, which might change the strength of the CD8-pMHC-I interaction, amplifying T cell cross-reactivity in chickens. The coreceptor CD8αα of TCR has evolved two peptide-MHC-I binding patterns in chickens, which might enhance the T cell response to major or emerging pathogens, including chicken-derived pathogens that are relevant to human health, such as high-pathogenicity influenza viruses.

The effects of migration on the immunity of Black-Headed Gulls (Chroicocephalus ridibundus: Laridae)

In order to elucidate the relationship between migration period and immunity related to susceptibility, we conducted research on Black-headed gulls (Chroicocephalus ridibundus). We captured 260 gulls and collected their peripheral blood. Their leukocyte (WBC) count, percentages of heterophils (Het) and lymphocytes (Lym), heterophil and lymphocyte ratio (H/L ratio), and CD4 and CD8α expression levels (CD4 and CD8α, respectively) were quantitatively analyzed over three migration periods (Autumn migration, Wintering, Spring migration). In Adult gulls, WBC counts and CD4 levels significantly increased. Moreover, the Het and H/L ratio decreased from the Autumn migration to Wintering. Conversely, only WBC counts and CD4 levels measurements significantly decreased from Wintering to Spring migration (P<0.05). The tested parameters of the Tokyo-bay population show a greater significant difference than the measurements of immunity of the Mikawa-bay population. This study suggests that the migratory period has a negative effect on an aspect of the immune system. Including the period-difference in the immune systems in the local population, it is necessary to investigate the relationship between the ecology of migratory birds and their immunity.

Impact of Reduced Dietary Crude Protein in the Starter Phase on Immune Development and Response of Broilers Throughout the Growth Period

Crude protein (CP) levels in commercial broiler (Gallus gallus) diets, optimized for maximum yield production vs. feed cost, have only begun to be assessed for impact on immune function. In order to study immune effects of dietary CP levels, different starter phase (day 1–14) diets were fed to 230 Ross 708 male broiler chicks randomly assigned at 1 day of age into two treatment groups. Group 1: Standard diet (STD) contained 3,000 kcal AMEn/kg energy and 23.78% CP; and Group 2: Reduced crude protein diet (RCP) contained 3,000 kcal AMEn/kg energy and 21.23% CP. From day 15–35 a common standard grower/finisher diet (3,150 kcal AMEn/kg energy and 22.18% CP) was allocated to both groups. Zymosan, a glycan derived from yeast cell walls that binds to TLR 2 and Dectin-1, was used for intra-abdominal challenge. Results demonstrated that a reduced crude protein starter diet (21.23 vs. 23.78% CP) between age 1–14, while maintaining the same levels of metabolizable energy and essential amino acids, did not affect broilers growth performance or lymphoid organ weights (P > 0.05). Interestingly, basal leukocyte levels in the RCP group significantly (P < 0.01) increased in the blood compartment at d35 in the unchallenged birds. Significant enhancements to leukocyte infiltration into the abdominal cavity were also detected post-immune challenge with zymosan (day 14 and day 35; P < 0.01). Post-challenge levels of TNF-α, IL-1β, and CXCL8 gene expression cells collected from the abdominal cavity were not affected by the diets (P > 0.05). Moreover, dietary treatments did not influence percentage of ROS producing cells in the abdominal cavity (P > 0.05). To our best knowledge, this is the first study that reports the impacts of reduced crude protein diet on the innate immune response of poultry to an acute inflammation model in the abdominal cavity. Overall, our results highlight that reduced crude protein diets can be used without negatively impacting broiler performance and may enhance the capacity of broilers to recruit leukocytes upon infection.

Techniques for the Measurement of Cell Mediated Immune Responses to Avian Influenza Virus

Cellular immune responses, through both T and B cells, are critical to understanding the role and regulation of lymphocytes following viral infection, as well as defining responses to vaccination. T cells play a critical role in adaptive immunity, including pathogen elimination through the engagement of CD4 and CD8 receptors, which trigger signaling mechanisms. B cells contribute to generating antibodies following exposure to foreign pathogens through interactions with CD4+ lymphocytes. While these different cell types have distinctly different modes of action in terms of contributions to protection (cytotoxic versus antibody mediated), they account for the majority of adaptive immunity induced following infection or vaccination. While the ability to measure cell-mediated immunity (CMI) has steadily improved, there is much to learn with regard to their contribution to the protection of birds against diseases induced by avian influenza virus. The rapidly increasing knowledge of genomic avian sequences, along with the increasing availability of monoclonal antibodies detecting avian cell-associated antigen markers, has made techniques to measure CMI more specific and informative for researchers.

Early Vaccination of Chickens Induces Suboptimal Immunity Against Infectious Bronchitis Virus

Infectious bronchitis virus (IBV) is highly prevalent in broiler chickens despite extensive vaccination commonly conducted early after hatch. The effects of early vaccination on immune responses were further investigated in chickens primed at increasing ages, followed by booster vaccination with an attenuated Arkansas (Ark) Delmarva Poultry Industry-type vaccine. Results show that vaccination on day 1 of age elicits significantly lower systemic and mucosal antibody responses compared with vaccination at later time points in the life of the chicken. The increase of IBV antibodies in serum from secondary responses after booster vaccination was more dramatic and significantly higher when measured by an Ark spike subunit 1 protein ELISA compared with measuring by non-Ark serotype whole-virus ELISA, which underlines the immunogenic importance of the virus spike at inducing antibodies. However, the levels achieved following boosting did not differ significantly between ages of priming. Thus, it seems that the booster vaccination mitigated the differences detected after prime immunization. In contrast to the continued rise of systemic antibodies after booster vaccination, the levels of mucosal IBV-specific immunoglobulin A decreased after booster vaccination. The recruitment or expansion of cluster of differentiation (CD)4⁺, CD8⁺, and CD4⁺/CD8⁺ T-cell populations in different immune effector sites was increased with age, but remained unaltered by IBV vaccination. In contrast, peripheral blood CD4⁺ cells showed a significant increase in IBV-vaccinated chickens compared with nonvaccinated age-matched controls both after primary and booster immunization. The results of the current study confirm that IBV vaccination on the day of hatch induces suboptimal IBV immune responses both in the systemic and mucosal compartments. This routine practice may be contributing to the immunologic escape of the virus and increased persistence of vaccine virus in vaccinated chickens. However, booster vaccination seems to overcome poor initial responses.

Sodium butyrate as an effective feed additive to improve growth performance and gastrointestinal development in broilers

This study was conducted to evaluate the effects of dietary sodium butyrate (SB) supplementation on growth performance, the development of gastrointestinal tract and immune organs (thymus, spleen and bursa of fabricius), and serum antibody titer after Newcastle disease (ND) vaccination in broilers. The total of 288 1-day-old broilers were randomly allocated to four groups with six replications according to initial body weight. Four treatment groups were designed as follows and fed the indicated diets: CON, basal diet; T1, basal diet supplemented with 0.3 g/kg SB; T2, basal diet supplemented with 0.6 g/kg SB; T3, basal diet supplemented with 1.2 g/kg SB. During days 1-21, broilers fed the T2 diet had higher (p < .05) average daily gain (ADG) than broilers fed the CON diet. On day 21, dietary SB supplementation showed linear increase (p < .05) in relative weight of the duodenum, jejunum, ileum, small intestine (the sum weight of duodenum, jejunum and ileum), pancreas and thymus, and linear increase (p < .05) in relative length of the duodenum, jejunum, ileum, small intestine (the sum length of duodenum, jejunum and ileum) and caeca. Meanwhile, dietary SB supplementation showed linear increase in the antibody titer against ND on days 14, 21, 28 and 35. In conclusion, dietary SB supplementation improved the development of gastrointestinal by increasing the relative weight and length, as well as enhanced the immune response of ND vaccine.

Immune responses upon in ovo HVT-IBD vaccination vary between different chicken lines

The genotype of chickens is assumed to be associated with variable immune responses. In this study a modern, moderate performing dual-purpose chicken line (DT) was compared with a high-performing layer-type (LT) as well as a broiler-type (BT) chicken line. One group of each genotype was vaccinated in ovo with a recombinant herpesvirus of turkeys expressing the virus protein VP2 of the infectious bursal disease virus (HVT-IBD) while one group of each genotype was left HVT-IBD unvaccinated (control group). Genotype associated differences in innate and adapted immune responses between the groups were determined over five weeks post hatch. HVT-IBD vaccination significantly enhanced humoral immune responses against subsequently applied live vaccines compared to non-HVT-IBD vaccinated groups at some of the investigated time points (P < 0.05). In addition HVT-IBD vaccination had depending on the genotype a significant impact on splenic macrophage as well as bursal CD4⁺ T-cell numbers (P < 0.05). On the other hand, the detectable genotype influence on Interferon (IFN) γ and nitric oxide (NO) release of ex vivo stimulated spleen cells was independent of HVT-IBD vaccination. The results of our study suggest considering a genotype specific vaccination regime in the field.

Selenium Rescues Aflatoxin B1-Inhibited T Cell Subsets and Cytokine Levels in Cecal Tonsil of Chickens

Cecal tonsil is the largest peripheral lymphoid organ of the gut-associated lymphoid tissue executing immune function. To evaluate the protective effect of selenium (Se) on the cecal tonsil of chicken exposed to aflatoxin B₁ (AFB₁), 144 1-day-old healthy Cobb chickens were randomly divided into four groups, and fed with basal diet (control group), 0.6 mg/kg AFB₁ (AFB₁ group), 0.4 mg/kg Se supplement (+Se group), and 0.6 mg/kg AFB₁ + 0.4 mg/kg Se supplement (AFB₁ + Se group) for 21 days, respectively. The results showed that AFB₁ significantly decreased the percentages of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ T cells, and the CD4⁺/CD8⁺ ratio, and suppressed the expressions of IL-2, IL-4, TNF-α, and IFN-γ mRNA in the cecal tonsil. However, Selenium (Se) supplied in the diets restored the percentages of T cell subsets, the CD4⁺/CD8⁺ ratio, and mRNA expressions of cytokines in the AFB₁ group to be close to those in the control group, and did not exhibit obvious toxicity to the cecal tonsil. These results indicated that Se exerted protective effect against AFB₁ on the functions of cecal tonsil, and also partially uncovered a new role of Se that could protect cecal tonsil of chickens from immunotoxicity of AFB₁.

Effect of High Dietary Manganese on the Immune Responses of Broilers Following Oral Salmonella typhimurium Inoculation

Manganese (Mn) is an essential nutrient for both host and pathogen. Recent studies have demonstrated the nutritional immunity of Mn against Salmonella infection in mammals. To investigate the effect of high dietary Mn on immune responses of broilers following Salmonella challenge, 144 1-day-old male broilers were fed a basal diet (containing 20.04 mg Mn/kg) plus an additional 40 (the control group) or 400 mg Mn/kg (the H-Mn group) for 7 days. The 72 broilers in each group were then orally inoculated with 5 × 10⁷ CFUs of Salmonella typhimurium (ATCC#14028) or phosphate-buffered saline. Peripheral blood, spleens, cecal tonsils, and bursa of Fabricius were collected from Salmonella-inoculated and Salmonella-noninoculated broilers (n = 6) at 2 days post inoculation (2 DPI) and 7 days post inoculation (7 DPI). Peripheral blood lymphocyte subpopulations were determined by flow cytometry. The messenger RNA (mRNA) abundance of genes was determined by quantitative real-time polymerase chain reaction. Salmonella counts were higher (P < 0.05) in the H-Mn group than that in the control group at 2 DPI in the cecal contents of Salmonella-inoculated broilers. High dietary Mn increased CD3⁺CD4⁺ and CD3⁺CD8⁺ percentages in the peripheral blood of Salmonella-inoculated broilers at 2 DPI. Salmonella inoculation increased interleukin (IL)-6 mRNA expression in spleens and bursa of Fabricius at 2 DPI and increased IL-1β and IL-6 mRNA expression in cecal tonsils at 7 DPI in the H-Mn group. These changes were not observed in the control group. High dietary Mn increased interferon-γ (IFN-γ) in spleens and decreased IFN-γ and IL-12 mRNA expression in cecal tonsils of Salmonella-inoculated broilers at 2 DPI. High dietary Mn decreased IL-17 mRNA expression in the bursa of Fabricius at 7 DPI, but increased this expression in cecal tonsils at 2 and 7 DPI in Salmonella-inoculated broilers. These results suggested that dietary Mn level affected T helper (Th) 1-cytokine reaction in spleens and cecal tonsils, and Th17-mediated immunity in cecal tonsils and the bursa of Fabricius of broilers when challenged with Salmonella.

Evaluation of blood monocyte and lymphocyte population in broiler chicken after vaccination and experimental challenge with Newcastle disease virus

In the present study, after vaccination and challenge with Newcastle disease virus, changes in the population of blood monocytes and lymphocytes of broiler chickens were evaluated using flow cytometry. 300 apparently healthy 1-day-old Cobb broiler chicks were divided randomly into four experimental groups (n=75). At 20days of age the chicks in group 1 and 2 were vaccinated with live B1 ND vaccine. Those in group 2 were additionally injected with a killed vaccine simultaneously and group 3 chicks received only the adjuvant of the killed vaccine. The birds in groups 1, 2 and 3 were challenged with a velogenic ND virus and those in group 4 were treated as control. Sampling was done on days 1,2,3,7 after vaccination and also on 1, 2, 3,7,14, 21 post challenge days. In this study percentage of B cell population was increased after vaccination and challenge in vaccinated birds, but CD3+ cells were decreased after vaccination and challenge, which showed B cells have more expansion than T cells. The CD4+ cell percentage in vaccinated birds was always lower than control birds. However, the percentage of CD8+ cells in vaccinated birds was increased. Results indicate increased CMI with the live NDV vaccination. In this study CD4/CD8 ratio in control birds was about 1.5 at 30days of age and it was slightly lower in vaccinated and challenged birds. The percentage of monocytes in vaccinated birds was significantly higher than control birds from 3days post vaccination to the end of the experiment.

The influence of age on Campylobacter jejuni infection in chicken

Campylobacter jejuni (C. jejuni)-host-interaction may be affected by the maturation stage of the chicken's immune system and the developing gut microbiota composition. We compared these parameters between birds C. jejuni-inoculated at day one, 10, 22 and 31 post hatch. The highest C. jejuni-colonization rate and numbers of colony forming units (CFU) were detected in caecal content of day-one-inoculated birds while the lowest was detected in 22-days-old birds. The low bacterial colonization of 22-days-old chickens correlated with the most prominent immune reactions in this age group in comparison to other age groups. Age and C. jejuni-inoculation had a significant effect on lymphocyte numbers and cytokine expression levels in caecum as well as on gut flora composition. Overall, the immune response to C. jejuni is significantly influenced by the age of the infected chickens leading to differences in C. jejuni-colonization pattern between age goups.

Impact of virus load on immunocytological and histopathological parameters during clinical chicken anemia virus (CAV) infection in poultry

Chicken anemia virus (CAV) is one the important pathogen affecting commercial poultry sector globally by causing mortality, production losses, immunosuppression, aggravating co-infections and vaccination failures. Here, we describe the effects of CAV load on hematological, histopathological and immunocytochemical alterations in 1-day old infected chicks. The effects of CAV on cytokine expression profiles and generation of virus specific antibody titer were also studied and compared with viral clearance in various tissues. The results clearly confirmed that peak viral load was achieved mainly in lymphoid tissues between 10 and 20 days post infection (dpi), being highest in the blood (log1010.63 ±0.87/ml) and thymus (log1010.29 ±0.94/g) followed by spleen, liver, bone marrow and bursa. The histopathology and immunoflowcytometric analysis indicated specific degeneration of T lymphoid cells in the thymus, spleen and blood at 15 dpi. While the transcript levels of interleukin (IL)-1, IL-2, IL-12 decreased at all dpi, interferon (IFN)-γ increased (3-15 fold) during early stages of infection and the appearance of virus specific antibodies were found to be strongly associated with virus clearance in all the tissues. Our findings support the immunosuppressive nature of CAV and provide the relation between the virus load in the various body tissues and the immunopathological changes during clinical CAV infections.

Characterization of host responses induced by Toll-like receptor ligands in chicken cecal tonsil cells

The innate responses of cecal tonsils against invading microorganisms are mediated by conserved pattern recognition receptors (PRRs) such as the Toll-like receptors (TLRs). TLRs expressed by mammalian and avian immune system cells have the capability to recognize pathogen-associated molecular patterns (PAMPs). Although, the role of TLR ligands in innate and adaptive responses in chickens has been characterized in spleen and bursa of Fabricius, considerably less is known about responses in cecal tonsils. The aim of the current study was to assess responses of mononuclear cells from cecal tonsils to treatment with the TLR2, TLR4 and TLR21 ligands, Pam3CSK4, lipopolysaccharide (LPS), and CpG oligodeoxynucleotide (ODN), respectively. All three ligands induced significant up-regulation of interferon (IFN)-γ, interleukin (IL)-1β, IL-6 and CxCLi2/IL-8, whereas no significant changes were observed in expression of IL-13 or the antimicrobial peptides, avian β-defensin (AvBD) 1, AvBD2 and cathelicidin 3 (CATHL-3). In general, CpG ODN elicited the highest cytokine responses by cecal tonsil mononuclear cells, inducing significantly higher expression compared to LPS and Pam3CSK4, for IFNγ, IL-1β, IL-6 and CxCLi2 at various time points. These findings suggest the potential use of TLR21 ligands as mucosal vaccine adjuvants, especially in the context of pathogens of the intestinal tract.

CD4+/CD8+ double-positive T cells: more than just a developmental stage?

CD4(+)/CD8(+) DP thymocytes are a well-described T cell developmental stage within the thymus. However, once differentiated, the CD4(+) lineage or the CD8(+) lineage is generally considered to be fixed. Nevertheless, mature CD4(+)/CD8(+) DP T cells have been described in the blood and peripheral lymphoid tissues of numerous species, as well as in numerous disease settings, including cancer. The expression of CD4 and CD8 is regulated by a very strict transcriptional program involving the transcription factors Runx3 and ThPOK. Initially thought to be mutually exclusive within CD4(+) and CD8(+) T cells, CD4(+)/CD8(+) T cell populations, outside of the thymus, have recently been described to express concurrently ThPOK and Runx3. Considerable heterogeneity exists within the CD4(+)/CD8(+) DP T cell pool, and the function of CD4(+)/CD8(+) T cell populations remains controversial, with conflicting reports describing cytotoxic or suppressive roles for these cells. In this review, we describe how transcriptional regulation, lineage of origin, heterogeneity of CD4 and CD8 expression, age, species, and specific disease settings influence the functionality of this rarely studied T cell population.

Effect of dietary antimicrobials on immune status in broiler chickens

This study evaluated the effects of dietary anticoccidial drugs plus antibiotic growth promoters (AGPs) on parameters of immunity in commercial broiler chickens. Day-old chicks were raised on used litter from a farm with endemic gangrenous dermatitis to simulate natural pathogen exposure and provided with diets containing decoquinate (DECX) or monensin (COBN) as anticoccidials plus bacitracin methylene disalicylate and roxarsone as AGPs. As a negative control, the chickens were fed with a non-supplemented diet. Immune parameters examined were concanavalin A (ConA)-stimulated spleen cell proliferation, intestine intraepithelial lymphocyte (IEL) and spleen cell subpopulations, and cytokine/chemokine mRNA levels in IELs and spleen cells. ConA-induced proliferation was decreased at 14 d post-hatch in DECX-treated chickens, and increased at 25 and 43 d in COBN-treated animals, compared with untreated controls. In DECX-treated birds, increased percentages of MHC2(+) and CD4(+) IELS were detected at 14 d, but decreased percentages of these cells were seen at 43 d, compared with untreated controls, while increased TCR2(+) IELs were evident at the latter time. Dietary COBN was associated with decreased fractions of MHC2(+) and CD4(+) IELs and reduced percentages of MHC2(+), BU1(+), and TCR1(+) spleen cells compared with controls. The levels of transcripts for interleukin-4 (IL-4), IL-6, IL-17F, IL-13, CXCLi2, interferon-γ (IFN-γ), and transforming growth factorβ4 were elevated in IELs, and those for IL-13, IL-17D, CXCLi2, and IFN-γ were increased in spleen cells, of DECX- and/or COBN-treated chickens compared with untreated controls. By contrast, IL-2 and IL-12 mRNAs in IELs, and IL-4, IL-12, and IL-17F transcripts in spleen cells, were decreased in DECX- and/or COBN-treated chickens compared with controls. These results suggest that DECX or COBN, in combination with bacitracin and roxarsone, modulate the development of the chicken post-hatch immune system.

Chicken biliary exosomes enhance CD4(+)T proliferation and inhibit ALV-J replication in liver

Exosomes, which are small membrane vesicles of endocytic origin, carry lipids, RNA/miRNAs, and proteins and have immune modulatory functions. In this study, we isolated exosomes from the bile of specific pathogen-free chickens, 42-43 days of age, by using an ultracentrifugation and filtration method. The density of the exosomes, isolated by sucrose gradient fractionation, was between 1.13 and 1.19 g/mL. Electron microscopic observation of the liver showed that exosomes were present in the space of Disse and bile canaliculus. Chicken biliary exosomes displayed typical saucer-shaped, rounded morphology. Using liquid chromatography mass spectrum methodology, 196 proteins, including exosomal markers and several unique proteins, were identified and compared with mouse biliary exosomes. Noteworthy, CCCH type zinc finger antiviral protein was found on chicken biliary exosomes never described before. Furthermore, our data show that chicken biliary exosomes promote the proliferation of CD4(+) and CD8(+) T cells and monocytes from liver. In addition, chicken biliary exosomes significantly inhibit avian leukosis virus subgroup J, which is an oncogenic retrovirus, from replicating in the DF-1 cell line. These data indicate that chicken biliary exosomes possess the capacity to influence the immune responses of lymphocytes and inhibit avian leukosis virus subgroup J (ALV-J).

Effects of dietary selenium on histopathological changes and T cells of spleen in broilers exposed to aflatoxin B1

Aflatoxin B1 (AFB1), which causes hepatocellular carcinoma and immune-suppression, is commonly found in feedstuffs. To evaluate the ability of selenium (Se) to counteract the deleterious effects of AFB1, two hundred 1-day-old male avian broilers, divided into five groups, were fed with basal diet (control group), 0.3 mg/kg AFB1 (AFB1 group), 0.3 mg/kg AFB1+0.2 mg/kg Se (+Se group I), 0.3 mg/kg AFB1+0.4 mg/kg Se (+Se group II) and 0.3 mg/kg AFB1+0.6 mg/kg Se (+Se group III), respectively. Compared with control group, the relative weight of spleen in the AFB1 group was decreased at 21 days of age. The relative weight of spleen in the three +Se groups was higher than that in the AFB1 group. By pathological observation, the major spleen lesions included congestion in red pulp and vacuoles appeared in the lymphatic nodules and periarterial lymphatic sheath in the AFB1 group. In +Se groups II and III, the incidence of major splenic lesions was decreased. The percentages of CD3+, CD3+CD4+ and CD3+CD8+ T cells in the AFB1 group were lower than those in control group from 7 to 21 days of age, while there was a marked increase in the three +Se groups compared to the AFB1 group. The results indicated that sodium selenite could improve the cellular immune function impaired by AFB1 through increasing the relative weight of spleen and percentages of splenic T cell subsets, and alleviating histopathological spleen damage.

Detection of cell-mediated immune response to avian influenza viruses

The measurement of cell-mediated immunity (CMI) is critical to understanding the role and regulation of avian lymphocytes following avian influenza virus (AIV) infection. While these different cell types have distinctly different modes of action in terms of contributions to protection, they account for the majority of adaptive immunity induced following infection or vaccination. Although the ability to measure CMI has steadily improved over the last few years, few studies have examined its role in protection of birds against AIV. The increasing availability of monoclonal antibodies recognizing various avian cell-associated antigens has made this technique more specific and informative.

Protective role of sodium selenite on histopathological lesions, decreased T-cell subsets and increased apoptosis of thymus in broilers intoxicated with aflatoxin B₁

For evaluating the ability of selenium (Se) in counteracting the adverse effects of aflatoxin B₁ (AFB₁), two hundred 1-day-old male Avian broilers, divided into five groups, were fed with basal diet (control group), 0.3 mg/kg AFB₁ (AFB₁ group), 0.3 mg/kg AFB₁+0.2 mg/kg Se (+Se group I), 0.3mg/kg AFB₁+0.4 mg/kg Se (+Se group II) and 0.3mg/kg AFB₁+0.6 mg/kg Se (+Se group III), respectively. Compared with control group, the decreased relative weight of thymus and percentages of mature thymocytes, congestion in medulla and much debris in cortex of thymus, and the increased apoptotic thymocytes were observed in AFB1 group. However, supplied dietary sodium selenite could increase the relative weight of thymus and percentages of mature thymocytes, and alleviate histopathological lesions. Compared with AFB1 group, the percentages of apoptotic thymocytes detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method and flow cytometry method in three +Se groups were decreased, the expression of Caspase-3 and Bax, through quantitative real-time PCR and immunohistochemical method, in three +Se groups were decreased, while the expression of Bcl-2 was increased. The results indicate that sodium selenite supplied in the diet, through a mechanism of apoptosis regulation, may ameliorated AFB₁-induced lesions of thymus and accordingly improve the impaired cellular immune function.

Towards the conservation of endangered avian species: a recombinant West Nile Virus vaccine results in increased humoral and cellular immune responses in Japanese Quail (Coturnix japonica)

West Nile Virus (WNV) arrived in North America in 1999 and is now endemic. Many families of birds, especially corvids, are highly susceptible to WNV and infection often results in fatality. Avian species susceptible to WNV infection also include endangered species, such as the Greater Sage-Grouse (Centrocercus uropbasianuts) and the Eastern Loggerhead Shrike (Lanius ludovicianus migrans). The virus has been shown to contribute towards the likelihood of their extinction. Although a clear and present threat, there exists no avian WNV vaccine available to combat this lethal menace. As a first step in establishing an avian model for testing candidate WNV vaccines, avian antibody based reagents were assessed for cross-reactivity with Japanese quail (Coturnix japonica) T cell markers CD4 and CD8; the most reactive were found to be the anti-duck CD8 antibody, clone Du-CD8-1, and the anti-chicken/turkey CD4 antibody, clone CT4. These reagents were then used to assess vaccine performance as well as to establish T cell populations in quail, with a novel population of CD4/CD8 double positive T cells being identified in Japanese quail. Concurrently, non-replicating recombinant adenoviruses, expressing either the WNV envelope or NS3 ‘genes’ were constructed and assessed for effectiveness as avian vaccines. Japanese Quail were selected for testing the vaccines, as they provide an avian model that parallels the population diversity of bird species in the wild. Both the level of WNV specific antibodies and the number of T cells in vaccinated birds were increased compared to unvaccinated controls. The results indicate the vaccines to be effective in increasing both humoral and cellular immune responses. These recombinant vaccines therefore may find utility as tools to protect and maintain domestic and wild avian populations. Their implementation may also arrest the progression towards extinction of endangered avian species and reduce the viral reservoir that potentiates infection in humans.

Protocatechuic acid, a new active substance against the challenge of avian infectious bursal disease virus

The present study aims to investigate the potential antiviral activity of protocatechuic acid (PCA) and its mechanism against infectious bursal disease virus (IBDV) infection. In the curative test, dosages of PCA of 40, 20, and 10 mg/kg, the survival rate was 90, 90, and 60%, respectively, and the BW gain was 36.63, 31.85, and 51.8%, respectively. The survival rate for the Astragalus polysaccharide (ASP) group was significantly lower than those of the birds treated with 20 mg/kg or 40 mg/kg of PCA. The bursa indeces of chickens in 40 mg/kg, 20 mg/kg, and ASP groups were significantly higher than that of the infection group, whereas a significant increase of the spleen index was found in birds with 20 mg/kg PCA in comparison with other challenged groups. The birds treated with 20 mg/kg or 40 mg/kg of 3,4-dihydroxybenzoic acid also showed slightly higher levels of IBDV clearance in the bursa of Fabricius. Furthermore, the chickens treated with 20 mg/kg of PCA induced a significant lymphocyte proliferation and a significant increase in the CD4+/CD8+ ratio in comparison with the ASP chickens. These results imply that chickens treated with 20 mg/kg of PCA for 5 d could effectively induce active nonspecific immune responses against the IBDV infection.

Combined use of etanercept and MTX restores CD4⁺/CD8⁺ ratio and Tregs in spleen and thymus in collagen-induced arthritis

OBJECTIVE

To further explore the mechanism of etanercept (ENT, rhTNFR:Fc) and methotrexate (MTX) in the combined treatment of rheumatoid arthritis (RA), we investigated whether thymic and splenic T-cell subsets and their related cytokines imbalance could be restored by ETN/MTX treatment.

METHODS

The effect of ETN/MTX on collagen-induced arthritis (CIA) was evaluated by arthritis scores, joint and spleen histopathology, as well as indices of thymus and spleen. T lymphocytes proliferation was determined by [(3)H]-TdR incorporation. Levels of TNF-α, LT-α, IL-1β, RANKL, IL-10, IL-17, IFN-γ and IL-6 were detected by enzyme linked immunosorbent assay. The subsets of T lymphocytes including CD4(+), CD8(+), CD3(+)CD4(+), CD4(+)CD25(+), CD4(+)CD62L(+) and CD4(+)CD25(+)Foxp3(+) cells were quantified using flow cytometry.

RESULTS

Combined administration of ETN/MTX significantly inhibited the proliferation of T lymphocytes, decreased serum IL-6, TNF-α, IL-1β, RANKL and macrophage supernatant IL-17, LT-α, increased serum IFN-γ and macrophage supernatant IL-10. Moreover, the combined administration could restore CD4(+)/CD8(+) ratio and Treg cells of CIA thymus and spleen.

CONCLUSION

Taken together, our findings suggest that ENT/MTX may modify the abnormal T lymphocytes balance from central to peripheral lymphoid organs, which may partially, explained the mechanism of the combined administration.

Comportamento de células do sistema imune frente ao desafio com Salmonella Enteritidis em aves tratadas e não tratadas com ácidos orgânicos

A Salmonelose é uma importante zoonose, considerada a principal causa de infecções bacterianas, sendo associada ao consumo de produtos avícolas. Como alternativa de controle, ácidos orgânicos têm sido amplamente usados. No entanto, pouco se conhece sobre o estado imunológico de aves de produção, e uma avaliação deste status é necessária para proteger frente a enfermidades e para garantir à aplicação segura de agentes terapêuticos ou imunização profilática. Este trabalho teve como objetivo verificar o comportamento do sistema imunológico das aves previamente infectadas com Salmonella Enteritidis (SE) tratadas com um composto de ácidos orgânicos em diferentes concentrações administrado via água e ração comparando com as aves infectadas e não tratadas. Foram inoculados 120 frangos de corte com 1mL de SE, via oral, na concentração de 1,0 x 108 UFC/mL, no 1º e 2º dia de idade, divididos em seis tratamentos com duas repetições, utilizando 200, 400, 500 e 1000ppm do ácido orgânico. Aos 35 dias de vida das aves, foram coletados, de todos os grupos, alíquotas de sangue de 3mL em tubo contendo EDTA para a avaliação das células imunes através de citometria de fluxo. Foram analisadas as porcentagens circulantes de células CD4+, CD8β+, MHC I+, MHC II+, TCRVβ1+, TCRVβ2+ e CD28+. Para análise microbiológica foram coletadas tonsilas cecais destas aves. Observou-se com esse estudo que os ácidos orgânicos nas dosagens 1000ppm na água e 500ppm na ração durante, dois e sete dias respectivamente antes do abate, foram eficazes na redução da infecção por SE em frangos de corte, comprovadas pelo método microbiológico e demonstradas através do comportamento das células do sistema imune. No presente estudo as aves infectadas apresentaram uma proporção menor de células T auxiliares circulantes quando comparadas às aves infectadas, mas tratadas com o AO ou com o grupo não infectado. A mesma tendência pode ser observada para as células CD28+, TCRVβ1+ e MHC IIbright+, e, com menor resolução, para CD8β+.

Effect of n-3 fatty acids on immune function in broiler chickens

There is interest in the enrichment of poultry meat with long-chain n-3 polyunsaturated fatty acids in order to increase the consumption of these fatty acids by humans. However, there is concern that high levels of n-3 polyunsaturated fatty acids may have detrimental effects on immune function in chickens. The effect of feeding increasing levels of fish oil (FO) on immune function was investigated in broiler chickens. Three-week-old broilers were fed 1 of 4 wheat-soybean basal diets that contained 0, 30, 50, or 60 g/kg of FO until slaughter. At slaughter, samples of blood, bursa of Fabricius, spleen, and thymus were collected from each bird. A range of immune parameters, including immune tissue weight, immuno-phenotyping, phagocytosis, and cell proliferation, were assessed. The pattern of fatty acid incorporation reflected the fatty acid composition of the diet. The FO did not affect the weight of the spleen, but it did increase thymus weight when fed at 50 g/kg (P < 0.001). Fish oil also lowered bursal weights when fed at 50 or 60 g/kg (P < 0.001). There was no significant effect of FO on immune cell phenotypes in the spleen, thymus, bursa, or blood. Feeding 60 g/kg of FO significantly decreased the percentage of monocytes engaged in phagocytosis, but it increased their mean fluorescence intensity relative to that of broilers fed 50 g/kg of FO. Lymphocyte proliferation was significantly decreased after feeding broiler chickens diets rich in FO when expressed as division index or proliferation index, although there was no significant effect of FO on the percentage of divided cells. In conclusion, dietary n-3 polyunsaturated fatty acids decrease phagocytosis and lymphocyte proliferation in broiler chickens, highlighting the need for the poultry industry to consider the health status of poultry when poultry meat is being enriched with FO.

Excess dietary vanadium induces the changes of subsets and proliferation of splenic T cells in broilers

The purpose of this 42-day study was to investigate the effects of dietary excess vanadium on immune function by determining changes of the subsets and proliferation function of splenic T cells. Four hundred twenty 1-day-old avian broilers were divided into six groups and fed on a corn-soybean basal diet as control diet or the same diet amended to contain 5, 15, 30, 45, and 60 ppm of vanadium supplied as ammonium metavanadate. When compared with those of the control group, the percentage of CD3+, CD3+CD4+, and CD3+CD8+ of splenic T cells were decreased in the 45 and 60 ppm groups; however, the percentage of CD3+ and CD3+CD4+ were increased in the 5 ppm group, and the CD4+/CD8+ ratios were raised in the 5 and 15 ppm groups at 14 days of age. Meanwhile, the proliferation of splenic T cells were depressed in the 45 and 60 ppm groups but raised in the 5 and 15 ppm groups. Also, the serum interleukin-2 (IL-2) and interleukin-6 (IL-6) contents were decreased in the 45 and 60 ppm groups and increased in the 5 ppm group. It was concluded that dietary vanadium in excess of 30 ppm changed the percentages of splenic T cell subsets and inhibited the proliferation of splenic T cells and reduced the serum IL-2 and IL-6 contents. The cellular immune function was finally impaired in broilers.

Effect of dietary high molybdenum on peripheral blood T-cell subsets and serum IL-2 contents in broilers

The objectives of this study were to investigate the effects of dietary high molybdenum (Mo) on immune function by determining changes of the subsets of peripheral blood T-cells and serum interleukin (IL)-2 contents. 300 1-day-old avian broilers were divided into four groups and fed on a corn-soybean basal diet as control diet or the same diet amended to contain 500; 1,000; and 1,500 mg/kg of Mo supplied as sodium molybdate dihydrate. In comparison with those of the control group, the percentages of CD3(+), CD3(+)CD4(+) and CD3(+)CD8(+) were decreased in 1,000 and 1,500 mg/kg of Mo intake groups from 14 days of age to 42 days of age. Also, the serum IL-2 contents were decreased in 1,000 and 1,500 mg/kg of Mo intake groups from 14 days of age to 42 days of age. Histopathologically, hypocellularity appeared in the thymus in 1,000 and 1,500 mg/kg of Mo intake groups. It was concluded that dietary high-Mo (1,000 mg/kg and 1,500 mg/kg) reduced the percentages of peripheral blood T-cell subsets and serum IL-2 contents and caused thymic lesions. The cellular immune function was finally injured in broilers.

Low dietary selenium induce increased apoptotic thymic cells and alter peripheral blood T cell subsets in chicken

The purpose of this 42-day study was to investigate the effects of low selenium (Se) on immune function by determining histopathological changes of thymus, apoptosis of thymic cells, and subpopulation of peripheral blood T cells. One hundred twenty 1-day-old avian broilers were randomly assigned to two groups of 60 each and were fed on a low Se diet (0.0342 mg/kg Se) or a control diet (0.2 mg/kg Se), respectively. The relative weight of thymus was significantly decreased in low Se group from 21 days of age in time-dependent manner when compared with that of control group. Histopathologically, lymphopenia in the cortex and medulla of thymus was observed in low Se group. In comparison with those of control group, the percentage of Annexin-V positive cells was increased, and the percentages of CD3(+) and CD3(+)CD8(+) T cells of the peripheral blood were decreased in low Se group, as measured by flow cytometry. These data suggested that low dietary Se induced histological lesions of thymus, increased apoptosis of thymic cells, and decreased T cell subsets. The cellular immune function was finally impaired in broilers.

Effect of vanadium on the subset and proliferation of peripheral blood T cells, and serum interleukin-2 content in broilers

The purpose of this 42-day study was to investigate the effects of dietary excess vanadium on immune function by determining changes of the subsets and proliferation function of peripheral blood T cells. Four hundred twenty 1-day-old avian broilers were divided into six groups and fed on a corn-soybean basal diet as control diet or the same diet amended to contain 5, 15, 30, 45, and 60 ppm vanadium supplied as ammonium metavanadate. In comparison with those of the control group, the percentages of CD (3) (+) , CD (3) (+) CD (4) (+) , and CD (3) (+) CD (8) (+) were decreased in 45 and 60 ppm groups from 14 to 42 days of age, and the percentages of CD (3) (+) and CD (3) (+) CD (4) (+) were increased in 5 ppm group at 42 days of age. The CD (4) (+) /CD (8) (+) ratio was increased in 45 and 60 ppm groups at 28 days of age. Meanwhile, the proliferation function of peripheral blood T cell were decreased in 30, 45, and 60 ppm groups from 14 to 42 days of age. Also, the serum interleukin-2 contents were decreased in 45 and 60 ppm groups from 14 to 42 days of age and increased in 5 ppm group at 28 days of age. Histopathologically, hypocellularity appeared in the thymus in 45 and 60 ppm groups. It was concluded that dietary vanadium in excess of 30 ppm reduced the percentages of peripheral blood T-cell subsets and the proliferation function and serum interleukin-2 contents. The cellular immune function was finally impaired in broilers.

Lesions of thymus and decreased percentages of the peripheral blood T-cell subsets in chickens fed on diets excess in selenium

Selenium is an essential trace element possessing immune-stimulatory properties. The purpose of this 42-day study was to investigate the effects of excess dietary selenium on cellular immune function by determining morphological changes of thymus and peripheral blood T-cell subset. Three hundred 1-day-old avian broilers were fed on a basic diet (0.2 mg/kg selenium) or the same diet amended to contain 1, 5, 10, 15 mg/kg selenium supplied as sodium selenite ( n = 60/group). Pathological lesions were progressed with the dietary Se level increased. Grossly, the volume of thymus was decreased. Histopathologically, lymphopenia and congestion were observed. Ultrastructurally, mitochondria injury was observed. In comparison with that of control group, 5, 10 and 15 mg/kg dietary Se decreased the percentage of CD3+, CD3+CD4+ and CD3+CD8+ T cells of the peripheral blood, as measured by flow cytometry. The results showed that excess selenium (more than 5 mg/kg) intake could cause lesions of thymus and decrease of T-cell subsets. The cellular immune function was finally impaired in broilers.

Efficacy of DNA vaccines carrying Eimeria acervulina lactate dehydrogenase antigen gene against coccidiosis

The efficacies of DNA vaccines encoding either Eimeria acervulina lactate dehydrogenase (LDH) antigen or a combination of LDH antigen and chicken IL-2 or IFN-gamma were evaluated against chicken coccidiosis. Three vaccine plasmids pVAX-LDH, pVAX-LDH-IFN-gamma and pVAX-LDH-IL-2 were constructed using the eukaryotic expression vector pVAX1. Expressions of proteins encoded by plasmids DNA in vivo were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay. Average body weight gain, oocyst output, survival rate and lesion scores were measured to evaluate the protective effects of vaccination on challenge infection. The results showed that DNA vaccines could obviously alleviate body weight loss, duodenal lesions, oocyst output and enhance oocyst decrease ratio. Anti-coccidial indexes (ACIs) of pVAX-LDH-IFN-gamma and pVAX-LDH-IL-2 groups were higher than that of other groups. Flow cytometric analysis of T lymphocytes in spleen and cecal tonsil demonstrated that DNA vaccines had significantly increased percentages of CD3(+) T cells compared with pVAX1 alone or TE buffer. The results provided the first proof that DNA vaccine carrying E. acervulina LDH antigen gene induced protective immunity against homologous infection and its effect could be enhanced by co-expression of chicken IL-2 or IFN-gamma.

Decreased percentages of the peripheral blood T-cell subsets and the serum IL-2 contents in chickens fed on diets excess in fluorine

Three hundred 1-day-old Avian broilers were divided into four groups and fed on control diet (F 23 ppm) and high-fluorine diets (400 ppm, high-fluorine group I; 800 ppm, high-fluorine group II; 1,200 ppm, high-fluorine group III) for 42 days (n=75/group). The percentages of CD4+ and CD8+ T cells were decreased in three high-fluorine groups when compared with those of control group. Meanwhile, the CD4+/CD8+ ratio were lower in high-fluorine group II at 28 days of age and in high-fluorine group III at 42 days of age than in control group. Also, the serum interleukin-2 (IL-2) contents were decreased in three high-fluorine groups when compared with those of control group. Histopathologically, the thymus became hypocellular in three high-fluorine groups. It was concluded that dietary fluorine excess (400~1,200 ppm) reduced the percentages of T-lymphocyte subsets and the serum IL-2 contents, and cellular immune function could be affected in chickens.

Altered monocyte and macrophage numbers in blood and organs of chickens injected i.v. with lipopolysaccharide

Lipopolysaccharide (LPS) is a Gram-negative bacteria cell wall component that activates monocytes and macrophages to produce nitric oxide (NO) from inducible nitric oxide synthase. Nitric oxide production in the plasma of chickens peaks 5-6-h post-i.v. LPS injection reflecting iNOS activation. To determine monocyte responsiveness after an i.v. LPS injection, a time course study was conducted examining the concentrations among peripheral blood leukocytes post-i.v. LPS injection in male and female chickens, the proportions among peripheral mononuclear leukocyte (PBMC; containing lymphocytes, thrombocytes, and monocytes) populations isolated from the blood samples collected at various times post-i.v. LPS treatment, and the ability of monocytes to produce NO with and without further LPS stimulation in vitro using the PBMC NO production assay. Additionally, monocyte extravasation activity was determined by analyzing macrophage proportions after the i.v. LPS injection in spleen, lung, and liver tissues. Blood was collected from male and female chickens at 0 h (pre-LPS injection control) and at 1, 3, 6, 24, and 48 h post-LPS injection, and additionally, at 72 h from female chickens. Tissues were collected 0, 1, 6, and 48 h post-i.v. LPS injection from male chickens. Monocyte concentrations dropped substantially by 1h in both males and females. In males, monocyte concentrations returned to control concentrations by 6h and increased at 24- and 48-h post-LPS injection, whereas in females, monocyte concentrations recovered more slowly, returning to near control concentrations by 24-48-h and increasing above control levels by 72 h. Lipopolysaccharide stimulated NO production by PBMC cultures established from blood samples obtained at various times post-LPS injection in vivo followed the same pattern as monocyte concentrations in the blood. Hence, NO concentrations within PBMC cultures were dependent upon the number of monocytes that were in the PBMC cultures isolated at different times post-i.v. LPS injection. Furthermore, macrophage proportions in spleen tissues responded similarly to monocyte concentrations in the blood, decreased in lung tissue, and varied widely in liver tissue throughout 48 h after an LPS injection. Monocytes and other leukocytes may attach to the endothelium post-i.v. LPS injection preventing the monocytes from entering the needle during blood collection resulting in what seems to be leukopenia in blood and in PBMC cultures attenuating NO production in PBMC cultures. Furthermore, monocyte differentiation and recruitment from the bone marrow is a likely contributor to the reconstitution and rise of monocyte concentrations in blood samples post-i.v. LPS injection.

The effect of selenium and vitamin E on the lymphocytes and immunoglobulin-containing plasma cells in the lymphoid organ and mucosa-associated lymphatic tissues of broiler chickens

The present research has been designed to understand the effect of selenium and vitamin E on the lymphocyte and changes in the frequency of Ig-containing plasma cells in the lymphatic organ and ileum (representative organ for mucosa-associated lymphatic tissues) of different postnatal stages of Kasilla broiler chickens. A routine haematoxylin and eosin (H and E) stain were used to study the histology of the lymphocytic changes, and indirect immunoperoxidase staining method was performed for the study of the distributional and dynamical changes of the Ig-containing plasma cells within the lymphatic tissues and in the ileum of control broilers and in the broilers supplemented with different concentration of selenium and vitamin E in the diet. Histologically, the population of lymphocytes decreased in the lobules of the thymus, medulla of bursal follicles, splenic masses, lymphatic nodules of the cecal tonsil, and villi of the ilium in 0.1 mg and 0.5 mg selenium supplemented broilers in comparison with the control. The population of these cells was found to increase in 150 mg and 300 mg vitamin E supplemented chickens in the present study. In the spleen IgG- and the IgM-containing plasma cells were more than IgA-containing plasma cells. In contrast, in the cecal tonsil and ileum IgA-containing plasma cells were more than IgG- and IgM-containing plasma cells. The frequency of these immunopositive cells were decreased in 0.1 mg and 0.5 mg selenium supplementated chickens, and increased their frequency in the chickens supplemented with 150 mg and 300 mg vitamin E. In the spleen the frequency of IgM-containing plasma cells and both in the cecal tonsil and ileum, the IgG-containing plasma cells were more decreased by selenium supplementation which restored in their population by vitamin E supplementation.