Vliagoftis H, Befus A D, Hollenberg M D, Moqbel R
Pulmonary Research Group, Department of Medicine, 574 HMRC, University of Alberta, Edmonton, AB, T6G 2S2, Canada.
J Allergy Clin Immunol. 2001 Apr;107(4):679-85. doi: 10.1067/mai.2001.114245.
Epithelium is considered an active participant in allergic inflammation. Proteinase-activated receptor (PAR) 2 is expressed in a variety of cell types, including epithelial cells, and has been implicated in inflammation.
PAR-2-mediated activation of airway epithelial cells induces the release of mediators that could promote eosinophil survival and mediate eosinophil recruitment.
PAR-2-activating peptides were used to activate the human airway epithelial cell line A549, as well as primary cultures of small airway epithelial cells (SAECs). Human peripheral blood eosinophils were cultured in the presence or absence of epithelial cell supernatants. Survival was assessed by using an Annexin V apoptosis detection kit. GM-CSF and eotaxin were measured by using ELISA.
Eosinophils undergo apoptosis in the absence of growth factors. Supernatants from PAR-2-activated A549 epithelial cells increased eosinophil survival. Supernatants from resting SAECs also increased eosinophil survival, but supernatants from PAR-2-activated SAECs showed a greater effect. The effect of PAR-2-activated epithelial cell supernatants on eosinophil survival was completely inhibited by a neutralizing anti-GM-CSF antibody but not an anti-IL-5 antibody. Resting A549 cells did not release any detectable GM-CSF, whereas PAR-2-activated cells released 35 pg/10(6) cells. Resting SAECs released 754.3 pg/10(6) cells of GM-CSF, which was further increased to 1360.5 pg/10(6) cells after PAR-2-mediated activation. Budesonide inhibited this PAR-2 effect. PAR-2-activated epithelial cells also released eotaxin.
PAR-2-mediated activation of airway epithelial cells induced release of GM-CSF, which promoted eosinophil survival and activation. It also induced release of eotaxin, which could mediate eosinophil recruitment to the airways.
上皮细胞被认为是过敏性炎症的积极参与者。蛋白酶激活受体（PAR）2在多种细胞类型中表达，包括上皮细胞，并且与炎症有关。
PAR-2介导的气道上皮细胞激活诱导可促进嗜酸性粒细胞存活并介导嗜酸性粒细胞募集的介质释放。
使用PAR-2激活肽激活人气道上皮细胞系A549以及小气道上皮细胞（SAECs）的原代培养物。在有或没有上皮细胞上清液的情况下培养人外周血嗜酸性粒细胞。使用膜联蛋白V凋亡检测试剂盒评估存活率。使用酶联免疫吸附测定法测量GM-CSF和嗜酸性粒细胞趋化因子。
嗜酸性粒细胞在没有生长因子的情况下会发生凋亡。PAR-2激活的A549上皮细胞的上清液可提高嗜酸性粒细胞的存活率。静息SAECs的上清液也可提高嗜酸性粒细胞的存活率，但PAR-2激活的SAECs的上清液显示出更大的作用。PAR-2激活的上皮细胞上清液对嗜酸性粒细胞存活的影响被中和抗GM-CSF抗体完全抑制，但抗IL-5抗体则无此作用。静息的A549细胞不释放任何可检测到的GM-CSF，而PAR-2激活的细胞释放35 pg/10(6)个细胞。静息的SAECs释放754.3 pg/10(6)个细胞的GM-CSF，在PAR-2介导的激活后进一步增加至1360.5 pg/10(6)个细胞。布地奈德抑制了这种PAR-2效应。PAR-2激活的上皮细胞也释放嗜酸性粒细胞趋化因子。
PAR-2介导的气道上皮细胞激活诱导GM-CSF释放，促进嗜酸性粒细胞存活和激活。它还诱导嗜酸性粒细胞趋化因子释放，这可介导嗜酸性粒细胞向气道募集。
