Molecular Mechanism of Barrier Function Changes of Epithelial Tight Junction in Allergic Rhinitis

1.我们使用Calu-3细胞系检测了组胺、白三烯D4（LTD 4）和凝血酶对上皮细胞对14 C标记的甘露醇和白蛋白的通透性的影响。10 μ <-6>M LTD 4不改变对甘露醇或白蛋白的渗透性。另一方面，组胺和10 <-7>μ M<-8>凝血酶显著增加上皮细胞对甘露醇的渗透性。此外，10 μ <-4>M组胺可显著增加辣根过氧化物酶穿过豚鼠鼻上皮紧密连接的通道.接下来，我们研究了组胺和凝血酶是否可以改变紧密连接蛋白的mRNA表达。我们将组胺或赋形剂加入培养的人鼻上皮细胞中，并在4小时后从它们中提取RNA。DNA酶处理后，RT-PCR扩增β-actin和ZO-1紧密连接蛋白的mRNA。组胺显著下调ZO-1 mRNA表达。这种作用被阻断预处理与美托洛尔，H1受体拮抗剂。接下来，我们检测了凝血酶对培养的上皮细胞中紧密连接蛋白mRNA表达的影响。凝血酶显著降低细胞ZO-1 mRNA的表达，但对occludin或claudin mRNA的表达没有影响。组胺和凝血酶导致ZO-1 mRNA减少可能导致鼻过敏反应期间粘膜通透性增加。

1. We examined the effect of histamine, leukotriene D4 (LTD4) and thrombin on the epithelial permeability to 14C labeled mannitol and albumin using Calu-3 cell lines. 10^<-6>M LTD4 did not change permeability to mannitol or albumin. On the other hand, histamine and 10^<-7>〜10^<-8> M thrombin significantly increased epithelial permeability to mannitol. Moreover, 10^<-4>M histamine significantly increased the passage of horseradish peroxidase across epithelial tight junction in guinea pig nose.2. Next we examined if histamine and thrombin can alter mRNA expression of tight junction proteins. We added histamine or vehicle to cultured human nasal epithelial cells and extracted RNA from them 4 hours later. After DNase treatment, mRNAs of β-actin and ZO-1 tight-junction protein were amplified by RT-PCR. Histamine significantly downregulated ZO-1 mRNA expression. This effect was blocked by pretreatment with mepyramine, an H1 receptor antagonist. Next we examined the effect of thrombin on the tight junction proteins mRNAs expression in cultured epithelial cells. Thrombin significantly decreased ZO-1 mRNA expression of the cells, but had no effect on the expression of occludin or claudin mRNAs. The reduction of ZO-1 mRNA by histamine and thrombin may cause increased permeability of the mucosa during allergic reactions in the nose.