Evidence of Platelet-Activating Factor Metabolic Pathway Activation in Human Nasal Mucosa Induced by Allergic Rhinitis

背景：血小板活化因子（PAP）具有广泛的生物学活性。在下呼吸道，PAF已被认为是部分负责支气管哮喘的生化介质。目的：探讨PAP在变应性鼻炎发病机制中的作用。本文对变应性鼻炎患者鼻粘膜组织中PAF及其合成酶PAF乙酰转移酶（PAF-AT）活性进行了检测。方法：对7例变应性鼻炎患者和3例正常鼻粘膜进行PAF生物测定，并对5例变应性鼻炎患者和5例正常鼻粘膜进行微粒体中PAF-AT的放射免疫测定。结果：变应性鼻炎患者鼻粘膜磷脂中PAF含量为4.56±0.81pg/ μ g（平均值±标准误，n=7），血小板聚集活性为PAF的定量。对照组PAF接近或低于检测水平。在鼻粘膜微粒体中，所有样品中均检测到特异性PAF-AT活性，且变应性鼻粘膜中的酶活性显著高于正常鼻粘膜。结论：变应性鼻炎患者鼻黏膜组织中PAF的产生可能与变应性鼻炎的发病机制有关。

Background : Platelet-activating factor (PAP) has a wide range of biological activities. In the lower airways, PAF has been suggested to act as the biochemical mediator partly responsible for bronchial asthma. However, the role of PAF in allergic rhinitis has not been established.Objective : The purpose of this study was to explore the possible role of PAP in the pathogenesis of allergic rhinitis. PAF and PAF-synthesizing enzyme PAF acetyltransferase (PAF-AT) activity in mucosal tissue from patients with allergic rhinitis were investigated. Furthermore, the production of PAF in fresh stimulated nasal mucosa was also studied.Methods : Bioassay for PAF was performed on 7 samples from patients with allergic rhinitis and 3 sample of normal mucosa, and radioimmunoassay for PAF-AT in the microsomal fraction was carried out on 5 samples from patients and normal subjects. Incubation of replicates of fresh nasal mucosa from patients with allergic rhinitis in the presence of calcium ionophore A23187 and antihuman immunoglobline E and the production of PAF were also assayed.Results : PAF was quantitated by platelet-aggrigating activity and found to have 4.56±0.81pg/ μ g phosphorus in nasal mucosal phospholipids (mean±SE, n=7) for patients with allergic rhinitis. In contrast, PAF was near or below the level of detection for the control group. In microsomes from nasal mucosa, specific PAF-AT activity was detected in all samples, and the enzymatic activities were significantly higher in allergic mucosa compared with normal mucosa. Nasal mucosa from patients with allergic rhinitis had the potential to produce PAF upon stimulation.Conclusion : The findings indicate that the metabolic pathway leading to PAF generation is activated during the pathogenesis of allergic rhinitis.