围产期奶牛 Nod-2 受体表达变化及其对中性粒细胞呼吸爆发功能的影响

【目的】围产期奶牛对细菌性疾病的易感性升高。本研究的目的在于探讨 Nod-2 受体在围产期奶牛中性粒细胞（PMN）中的表达变化及其对 PMN 细胞呼吸爆发功能的影响，以揭示 Nod-2 在围产期奶牛免疫机能改变中的作用。【方法】 采用 RT-PCR 法检测围产期和非围产期泌乳奶牛外周 PMN 细胞中 Nod-2 mRNA 的表达变化；全血分别用佛波醇酯（PMA）和 Nod-2 受体特异性配体胞壁酰基二肽 MDP 刺激，采用流式细胞仪检测 PMN 呼吸爆发功能。【结果】围产期奶牛 PMN 细胞 Nod-2 mRNA 表达量显著低于非围产期奶牛（P＜0.05）；受 PMA 刺激后，围产期奶牛 PMN 呼吸爆发功能显著低于非围产期奶牛（P＜0.05）；受 MDP 刺激后，围产期奶牛 PMN 呼吸爆发功能亦较非围产期奶牛下降。【结论】围产期奶牛对细菌性疾病易感性升高可能与 Nod-2 mRNA 表达下调有关。

Expression of Nod-2 Receptor in Periparturient Dairy Cows and Its Effect on Neutrophils Respiratory Burst

【Objective】 Dairy cows are more susceptible to bacterial diseases around parturition.The present study was conducted to investigate the expression of Nod-2 in the polymorphonuclear neutrophil leukocytes(PMN) from periparturient cows and its effect on PMN respiratory burst,with the purpose to evaluate whether the Nod-2 receptor contributes to the increased susceptibility of periparturient cows to bacterial diseases.【Method】 The Nod-2 mRNA in PMN from periparturient and non-periparturient cows was detected by RT-PCR.Function of respiratory burst in PMNs was evaluated by flow cytometry following the stimulation of the whole blood with phorbol-12-myristate-13-acetate(PMA) and the ligand of Nod-2,muramyl dipeptide(MDP),respectively.【Result】 It was found that the blood PMN from periparturient cows had decreased Nod-2 mRNA expression than that from non-periparturient lactating cows(P<0.05),and their ability of respiratory burst responding to PMA stimulation was decreased(P<0.05).Upon the MDP stimulation,PMNs from periparturient cows showed decreased respiratory burst as well.【Conclusion】 It was suggested that the reduced Nod-2 mRNA expression might contribute to the increased susceptibility to bacterial infection in periparturient cows.