Regulation of the MyD88 gene in chicken spleen inflammation induced by stress.

In order to investigate the regulatory role of the myeloid differentiation factor 88 (MyD88) gene in the stress inflammatory response to chicken spleen, the chicken stress model and macrophage (HD11) inflammation model were constructed in this study. Enzyme-linked immunosorbent assay and quantitative real-time PCR were used to investigate the effects of MyD88 on immune and inflammatory indicators. The results demonstrated that the levels of IgG, CD3+ and CD4+ in the serum of chickens in the beak trimming stress and heat stress groups decreased significantly compared to the control group without stress (P < 0.05), and the inflammation-related indices IL-1ß, TNF-α, IL-6 and NF-κB increased significantly (P < 0.05). Stress up-regulated the expression levels of MyD88, IL-1ß, NF-κB and TLR4 in the spleen, stimulated the release of inflammatory factors. Overexpression of MyD88 significantly up-regulated the expression levels of the inflammatory factors IL-1ß, TNF-α, IL-8, NF-κB and TLR4 in HD11 cells (P < 0.05). Co-treatment with lipopolysaccharide (LPS) further promoted the expression levels of the inflammatory cytokines in HD11 cells. Interference with the expression of MyD88 significantly reduced the expression level of inflammatory factors in HD11 cells (P < 0.05) and had an antagonistic effect with LPS to alleviate the inflammatory reaction. In conclusion, the MyD88 gene has a pro-inflammatory effect and is highly expressed in the beak trimming and heat stress models in chicks, regulating the inflammatory response in poultry. It was involved in regulating the expression of immune-related genes in HD11 cells and had a synergistic effect with LPS.

In this study, we constructed two chick stress models and a chicken macrophage (HD11) inflammation model to verify the potential mechanism of the myeloid differentiation factor 88 (MyD88) gene regulation of inflammatory response in poultry for the first time through in vivo and in vitro dual model tests. The results of this study preliminarily suggest that the MyD88 gene may be a reliable indicator of an inflammatory state in poultry and a key target for regulating the poultry inflammatory response.