PDE4在金葡菌诱导的奶牛乳腺炎中的作用及分子机制

病原菌感染是奶牛乳腺炎的主要发病原因，通常采用抗生素疗法能够有效控制其感染，但长期使用会造成耐药性等问题。据报道，PDE4可以作为免疫调节剂治疗肺炎和神经炎症相关的疾病。抑制PDE4能够提升细胞中cAMP浓度，抑制LPS诱导的炎症细胞因子的释放。据此，本项目提出抑制乳腺组织PDE4可降低金葡菌诱导的乳腺炎的假设。拟通过金葡菌感染乳腺组织和乳腺上皮细胞分别建立体内和体外实验模型，检测cAMP-PDE的基因表达变化及PDE4的活性变化，明确金葡菌感染引起PDE家族差异表达；检测PDE4抑制剂对中性粒细胞积聚和对促炎细胞因子TNF-α、IL-1β和IL-6活性的影响，评价PDE4抑制剂的抗炎效果；检测PDE4抑制剂和/或PKA抑制剂对IκB、p65、ERK、p38、JNK和CREB磷酸化水平的影响，阐明PDE4抑制剂的抗炎分子机制，为临床治疗金葡菌性乳腺炎开发新的治疗靶点及提供理论依据。

Pathogen infection is the main cause of bovine mastitis. Antibiotic therapy could effectively control the infection, but could also introduce problems, such as resistance, for a long-term use. It has been reported that PDE4 served as an immune modulator in diseases associated with pneumonia and neuroinflammation. Inhibition of PDE4 could suppress LPS induced release of inflammatory cytokines by elevating intracellular cAMP. Thus, this project put forward the hypothesis that inhibiting the PDE4 family in mammary gland could reduce the mastitis induced by Staphylococcus aureus. Mammary gland and mammary epithelial cells stimulated by Staphylococcus aureus are used as a mastitis model in vivo and in vitro, respectively, to clarify the expression differences of PDE family by detecting the cAMP-PDE gene expression and the PDE4 activity; to evaluate the anti-inflammatory effect of PDE4 inhibitor by detecting the neutrophil accumulation, TNF-α, IL-1β and IL-6 activity; and to further demonstrate the related mechanism by detecting the effect of PDE4 inhibitor and/or PKA inhibitor on the phosphorylation of IκB, p65, ERK, p38, JNK and CREB. Finally, this project will be helpful to develop a new therapeutic target for the treatment of Staphylococcal aureus induced mastitis and to provide theoretical basis.