Impact of Sensitization and Inflammation on the Interaction of Mast Cells With the Intestinal Epithelium in Rats
Impact of Sensitization and Inflammation on the Interaction of Mast Cells With the Intestinal Epithelium in Rats
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DOI：
10.3389/fphys.2019.00329
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发表时间：
2019-03-26
影响因子：
4
通讯作者：
Diener, Martin
中科院分区：
文献类型：
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作者：
Becker, Jasmin;Ott, Daniela;Diener, Martin
据报道，在炎症性肠病（IBD）期间，肠肥大细胞的密度增加。由于肥大细胞介体已知可增加上皮紧密连接的通透性，我们推测致敏动物的抗原反应可能在炎症条件下增强。这将通过进一步增强管腔抗原进入结肠壁从而在IBD期间继续不充分的免疫应答而促成恶性循环。因此，一组大鼠对卵清蛋白致敏。另外，在第二组动物中，通过直肠施用溶解在乙醇中的2，4，6-三硝基苯磺酸（TNBS）诱导结肠炎。将来自远端结肠和空肠（作为远离发炎区域的肠段）的样本固定在Ussing室中以测量组织电导、由抗原暴露诱导的短路电流（I-sc）和细胞旁渗透性（荧光素通量）。通过免疫荧光和qPCR测定肥大细胞标志物和紧密连接蛋白来证实这一点。与最初的假设相反，抗原诱导的Isc在结肠炎动物的组织中没有上调，但在结肠和空肠中倾向于下调。仅在空肠肥大细胞脱颗粒引起荧光素通量增加。肥大细胞密度在结肠炎动物的结肠中没有显著改变。在空肠中，致敏诱导肥大细胞密度强烈增加，这不受额外诱导结肠炎的影响。与未致敏动物相比，致敏动物中密封紧密连接组分claudin-3和claudin-4的表达在蛋白质水平上增加。结肠炎的额外诱导引起两个肠段中的紧密连接蛋白-3的下调和空肠中的紧密连接蛋白-4的上调。因此，这些数据表明肥大细胞-上皮相互作用的片段差异，但在预先致敏后的TNBS/乙醇急性结肠炎模型中没有离子分泌的增强。
The density of intestinal mast cells has been reported to increase during inflammatory bowel disease (IBD). As mast cell mediators are known to increase the permeability of epithelial tight junctions, we hypothesized that antigen responses in sensitized animals might be enhanced under inflammatory conditions. This would contribute to a vicious circle by further enhancing the entry of luminal antigens into the colonic wall and thereby continuing the inadequate immune response during IBD. Therefore, one group of rats was sensitized against ovalbumin. In a second group of animals additionally a colitis was induced by rectal administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) dissolved in ethanol. Specimens from distal colon and jejunum (as intestinal segment located distantly from the inflamed area) were mounted in Ussing chambers to measure tissue conductance, short-circuit current (I-sc) induced by antigen exposure and paracellular permeability (fluorescein flux). This was paralleled by determination of mast cell markers and tight junction proteins with immunofluorescence and qPCR. In contrast to the initial hypothesis, antigen-induced Isc was not upregulated, but tended to be downregulated in the tissues from the colitis animals, both in colon and in jejunum. Only in the jejunum mast cell degranulation evoked an increase in fluorescein flux. Mast cell density was not altered significantly in the colon of the colitis animals. In the jejunum, sensitization induced a strong increase in mast cell density, which was unaffected by additional induction of colitis. Expression of sealing tight junction components claudin-3 and -4 were increased on the protein level in the sensitized animals in comparison to non-sensitized animals. Additional induction of colitis evoked a downregulation of claudin-3 in both intestinal segments and an upregulation of claudin-4 in the jejunum. Consequently, these data indicate segment differences in mast cell - epithelium interaction, but no enhancement of ion secretion in the TNBS/ethanol model of acute colitis after prior sensitization.