Exogenous nitric oxide stimulates early egress of Eimeria tenella sporozoites from primary chicken kidney cells in vitro

Inhibitory effect of Eimeria maxima IFN-γ inhibitory molecules on the immune function of T cell subsets in chickens

It has been reported that infection of chicken coccidian could inhibit the production of Th1 cytokine IFN-γ, thereby evading clearance by the host immune system. The present study aimed to have a further investigation into the effects of Eimeria maxima IFN-γ inhibitory molecules (EmHPSP-2 and EmHPSP-3) on the immune function of chicken peripheral blood mononuclear cells (PBMC) and various T cell subsets. First, separated PBMC or sorted T cell subsets were used for incubation with recombinant proteins of EmHPSP-2 (rEmHPSP-2) and EmHPSP-3 (rEmHPSP-3). Subsequently, the effects of rEmHPSP-2 and rEmHPSP-3 on proliferative capacity, nitric oxide (NO) release and mRNA levels of cytokines of the above cells were detected. The sorting purity of CD8+, CD4+ CD25-, CD4+, and CD4+ CD25+ T cells was 93.01, 88.88, 87.04, and 81.26%, respectively. The NO release of PBMC was significantly inhibited by rEmHPSP-2 and rEmHPSP-3. The proliferation of PBMC and CD4+ T cells was significantly inhibited by rEmHPSP-2 and rEmHPSP-3, whereas CD8+, CD4+ CD25-, and CD4+ CD25+ T cells was significantly promoted by the 2 proteins. The 2 proteins significantly downregulated interferon-gamma (IFN-γ) mRNA level, upregulated the transcriptional levels of interleukin-10 (IL-10) and transforming growth factor-beta1 (TGF-β1) in PBMC. IFN-γ and IL-2 transcriptional levels were markedly inhibited in CD8+ T cells. IFN-γ transcriptional level was significantly inhibited, but IL-4 was promoted by rEmHPSP-2 and rEmHPSP-3 in CD4+ CD25- T cells. Meanwhile, the inhibitory effects of rEmHPSP-2 and rEmHPSP-3 on the transcriptional levels of IFN-γ and IL-2 were more obvious in CD4+ T cells containing CD25+ cells compared with the CD25+ cells depletion group. It was found that IL-10, TGF-β1, and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) mRNA levels were significantly upregulated upon stimulation of chicken CD4+ CD25+ T cells by proteins. This study is not only of great significance to clarify the immune evasion mechanism of chicken coccidia, but also provides candidate antigen molecules for development of a novel vaccine against chicken coccidiosis.

Transcriptomic, 16S ribosomal ribonucleic acid and network pharmacology analyses shed light on the anticoccidial mechanism of green tea polyphenols against Eimeria tenella infection in Wuliangshan black-boned chickens

BACKGROUND

Eimeria tenella is an obligate intracellular parasitic protozoan that invades the chicken cecum and causes coccidiosis, which induces acute lesions and weight loss. Elucidating the anticoccidial mechanism of action of green tea polyphenols could aid the development of anticoccidial drugs and resolve the problem of drug resistance in E. tenella.

METHODS

We constructed a model of E. tenella infection in Wuliangshan black-boned chickens, an indigenous breed of Yunnan Province, China, to study the efficacy of green tea polyphenols against the infection. Alterations in gene expression and in the microbial flora in the cecum were analyzed by ribonucleic acid (RNA) sequencing and 16S ribosomal RNA (rRNA) sequencing. Quantitative real-time polymerase chain reaction was used to verify the host gene expression data obtained by RNA sequencing. Network pharmacology and molecular docking were used to clarify the interactions between the component green tea polyphenols and the targeted proteins; potential anticoccidial herbs were also analyzed.

RESULTS

Treatment with the green tea polyphenols led to a reduction in the lesion score and weight loss of the chickens induced by E. tenella infection. The expression of matrix metalloproteinase 7 (MMP7), MMP1, nitric oxide synthase 2 and ephrin type-A receptor 2 was significantly altered in the E. tenella infection plus green tea polyphenol-treated group and in the E. tenella infection group compared with the control group; these genes were also predicted targets of tea polyphenols. Furthermore, the tea polyphenol (-)-epigallocatechin gallate acted on most of the targets, and the molecular docking analysis showed that it has good affinity with interferon induced with helicase C domain 1 protein. 16S ribosomal RNA sequencing showed that the green tea polyphenols had a regulatory effect on changes in the fecal microbiota induced by E. tenella infection. In total, 171 herbs were predicted to act on two or three targets in MMP7, MMP1, nitric oxide synthase 2 and ephrin type-A receptor 2.

CONCLUSIONS

Green tea polyphenols can directly or indirectly regulate host gene expression and alter the growth of microbiota. The results presented here shed light on the mechanism of action of green tea polyphenols against E. tenella infection in chickens, and have implications for the development of novel anticoccidial products.

Novel Antioxidant Insights of Myricetin on the Performance of Broiler Chickens and Alleviating Experimental Infection with Eimeria spp.: Crosstalk between Oxidative Stress and Inflammation

In the modern poultry industry, the application of novel phytogenic bioactive compounds with antioxidant potential aims to enhance productivity and quality and to minimize the stress of associated diseases. Herein, myricetin, a natural flavonoid, was evaluated for the first time on broiler chickens' performance, antioxidants and immune modulating functions, and tackling avian coccidiosis. A total of 500 one-day-old chicks were divided into five groups. The negative (NC) and infected control (IC) groups were fed a control diet without additives, and the latter was infected with Eimeria spp. Groups supplemented with myricetin (Myc) were fed a control diet of Myc (200, 400 and 600 mg/kg diet each). On d 14, all chicks except those in NC were challenged with oocysts of mixed Eimeria spp. Significant improvements in the overall growth rate and feed conversion ratio were detected in the group that was fed 600 mg/kg, unlike the IC group. Notably, groups that were fed 400 and 600 mg/kg showed higher total meat antioxidant capacity with an inverse reduction in oxidative and lipid peroxidation biomarkers (hydrogen peroxide: H₂O₂; reactive oxygen species: ROS; Malondialdehyde: MDA). Of note, the upregulation of glutathione peroxidase; GSH-Px, catalase; CAT, superoxide dismutase; SOD, heme oxygenase-1; HO-1 and NAD(P)H dehydrogenase quinone 1 NQO1 genes in jejunum and muscle were prominently observed with increasing levels of supplemental Myc. At 21 dpi, the severity of coccoidal lesions (p < 0.05) induced by mixed Eimeria spp. and oocyst excretion were greatly reduced in the group that was fed 600 mg/kg of Myc. In the IC group, higher serum levels of C-reactive protein; CRP and nitric oxide; and NO and the upregulated expression of inflammatory biomarkers (interleukin-1β; IL-1β, interleukin-6; IL-6, tumor necrosis factor-α; TNF-α, chemotactic cytokines; CCL20, stromal cell-derived factor-1; CXCL13, and avian defensins; AvBD612) were subsided in higher levels in the Myc-fed groups. Taken together, these findings indicate the promising antioxidant role of Myc in modulating immune responses and reducing growth depression associated with coccidia challenges.

Anticoccidial efficacy of Garcinia kola (Heckel H.) against experimental Eimeria tenella infection in chicks

There is a need to advance commercial poultry production to cater to the essential protein needs of an ever-increasing population, however, the rampant occurrence of coccidiosis infection poses a threat to this achievement. This study evaluated the in vivo anticoccidial activities of the extracts and fractions of Garcinia kola against experimental Eimeria tenella infection using broiler chickens as experimental subjects. A total of 40 broiler chicks were experimentally infected with E. tenella and assigned randomly into five groups consisting of eight chicks each. Three days post experimental infection groups I and II were administered orally with tween 80 (0.8%) and Amprolium (30 mg/kg) and served as untreated and treated control groups, respectively whereas Groups III, IV, and V were administered orally with crude methanol extract (CME) at doses of 200, 400 and 600 mg/kg, respectively, for five consecutive days. Daily weight gains were recorded and faecal oocysts per gram (OPG) counts were made by the McMaster Egg counting technique. Blood samples from each experimental group were collected on days 0, 3, 6, and 8 for haematological examination. In the acute toxicity studies, the CME of G. kola did not produce any toxic effect or mortality at doses between 10 and 5000 mg/kg. The CME G. kola was then considered safe and the LD50 was assumed to be > 5000 mg/kg. Graded doses of CME of G. kola considerably (P < 0.05) improved body weight gain and decreased OPG in a dose-depended manner. There was also significant improvement in the Packed Cell Volume (PCV), Red Blood Cell (RBC) and White Blood Cell (WBC) counts upon treatment with the graded doses of CME of G. kola. Besides, G. kola significantly decreased histopathological lesions in the caecum. The results of this study indicates that G. kola may provide beneficial effects against E. tenella-induced coccidiosis in broiler chickens.

Coccidia-Microbiota Interactions and Their Effects on the Host

As a common parasitic disease in animals, coccidiosis substantially affects the health of the host, even in the absence of clinical symptoms and intestinal tract colonization. Gut microbiota is an important part of organisms and is closely related to the parasite and host. Parasitic infections often have adverse effects on the host, and their pathogenic effects are related to the parasite species, parasitic site and host-parasite interactions. Coccidia-microbiota-host interactions represent a complex network in which changes in one link may affect the other two factors. Furthermore, coccidia-microbiota interactions are not well understood and require further research. Here, we discuss the mechanisms by which coccidia interact directly or indirectly with the gut microbiota and the effects on the host. Understanding the mechanisms underlying coccidia-microbiota-host interactions is important to identify new probiotic strategies for the prevention and control of coccidiosis.