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.

Effects of Oral Probiotic Feeding on Toll-Like Receptor Gene Expression of the Chicken's Cecal Tonsil

BACKGROUND

It was proposed that probiotics may influence immune system through direct or indirect exposure. Direct exposure is mostly mediated by surface receptors. Toll-like receptors (TLRs) are conserved molecular sensors which could be triggered via some pathogen associated structures, hence, modulate the immune responses. This study was conducted to elucidate the impact of lactobacillus acidophilus as a common probiotic on the expression level of TLRs in the chicken's cecal tonsil.

METHODS

Thirty one-day-old chicken were selected and separated into three groups as probiotic-fed, dairy-fed and control. In addition to commercial powder supply, each chicken in the probiotic-fed group received 109 CFU/Kg of L. acidophilus daily. While, chickens in the dairy-fed group were provided with commercial powder feed and sterile dairy milk. After 14 and 21 days of oral feeding the cecal tonsil was removed and the expression of TLR2, TLR4 and TLR5 were examined by real-time PCR.

RESULTS

At the age of 14-day, there was a slight upregulation in the expression levels of TLR2 (118.9%), TLR4 (129.6%) and TLR5 (123.7%) of the cecal tonsil in the probiotic-fed group; however, these alterations were not statistically significant. At the age of 21-day, a non-significant downregulation was observed in TLR expression level of both dairy-fed (TLR2, 85%; TLR4, 79.5%; and TLR5, 86.5%) and probiotic-fed (TLR2, 88.8%; TLR4, 81%; and TLR5, 87.2%) groups in comparison to controls.

CONCLUSION

The findings revealed that although the probiotic supplementation could be useful but it did not significantly affect innate immunity state through alteration of TLRs.

Dietary nickel chloride induces oxidative stress, apoptosis and alters Bax/Bcl-2 and caspase-3 mRNA expression in the cecal tonsil of broilers

The purpose of this study was to investigate the effects of dietary NiCl2 on antioxidant function, apoptosis, and the protein expression, mRNA expression and contents of the bcl-2, bax and caspase-3 in the cecal tonsil of broilers. 280 one-day-old avian broilers were divided into four groups and fed on a corn-soybean basal diet as control diet or the same basal diet supplemented with 300, 600 and 900 mg/kg of NiCl2 for 42 days. The activities of SOD, CAT and GSH-Px, and the ability to inhibit hydroxy radical, and GSH content were significantly decreased in all experimental groups. MDA content was significantly increased. The protein expression, mRNA expression and contents of bcl-2 were decreased, and bax and caspase-3 were increased in all experimental groups. The percentages of apoptotic lymphocytes were significantly increased. In conclusion, dietary NiCl2 in excess of 300 mg/kg caused oxidative stress, and then induced decreased the protein expression, mRNA expression and the contents of bcl-2, and increased protein expression, mRNA expression and the contents of bax and caspase-3 proteins in the cecal tonsil. The local intestinal mucosal immunity could finally be impaired due to the oxidative stress and apoptosis in the cecal tonsil caused by NiCl2.