Division of Cardiovascular Medicine, Taoyuan Armed Forces General Hospital, Taoyuan City, Taiwan.
Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City, Taiwan.
Int Immunopharmacol. 2021 Jul;96:107620. doi: 10.1016/j.intimp.2021.107620. Epub 2021 Apr 13.
Histamine is released from mast cells when tissues are inflamed or stimulated by allergens. Activation of histamine receptors and calcium influx via TRPV1 could be related to histamine-induced itch and skin inflammation. Quercetin is known to have anti-inflammatory and anti-itching effects. This study aims to understand whether quercetin can directly affect histamine-induced calcium influx in human keratinocyte. In it, we investigated quercetin, which acts on histamine-induced intracellular free calcium ([Ca]i) elevation in human keratinocyte. Changes in [Ca]i were measured using spectrofluorometry and confocal Imaging. We detected the expression of IL-8 after treatment of quercetin using qRT-PCR and evaluated its anti-itching effect in BALB/c mice. We also performed a docking study to estimate the binding affinity of quercetin to H4 receptors. We found that quercetin pretreatment decreased histamine-induced [Ca]i elevation in a concentration-dependent manner. The inhibitory effect of quercetin on histamine-induced [Ca]i elevation was blocked by JNJ7777120, a selective H antagonist, as well as by U73122, a PLC inhibitor, and by GF109203X, a PKC inhibitor. We also found that H4 agonist (4-methylhistamine)-induced [Ca]i elevation could be inhibited by quercetin. Moreover, the selective TRPV1 blocker capsazepine significantly suppressed the quercetin-mediated inhibition of histamine-induced [Ca]i elevation, whereas the TRPV4 blocker GSK2193874 had no effect. Last, quercetin decreased histamine and H4 agonist-induced IL-8 expression in keratinocyte and inhibited the scratching behavior-induced compound 48/80 in BALB/c mice. The molecular docking study also showed that quercetin exhibited high binding affinities with H4 receptors (autodock scores for H4 = -8.7 kcal/mol). These data suggest that quercetin could decrease histamine 4 receptor-induced calcium influx through the TRPV1 channel and could provide a molecular mechanism of quercetin in anti-itching, anti-inflammatory, and unpleasant sensations.
当组织发炎或受到过敏原刺激时，肥大细胞会释放组织胺。组织胺受体的激活和 TRPV1 介导的钙内流可能与组织胺引起的瘙痒和皮肤炎症有关。槲皮素具有抗炎和止痒作用。本研究旨在了解槲皮素是否可以直接影响人角质形成细胞中组织胺诱导的钙内流。在这项研究中，我们研究了槲皮素对人角质形成细胞中组织胺诱导的细胞内游离钙([Ca]i)升高的作用。使用荧光光谱法和共聚焦成像测量[Ca]i的变化。我们使用 qRT-PCR 检测了槲皮素处理后 IL-8 的表达，并在 BALB/c 小鼠中评估了其止痒作用。我们还进行了对接研究，以估计槲皮素与 H4 受体的结合亲和力。我们发现，槲皮素预处理以浓度依赖的方式降低了组织胺诱导的[Ca]i升高。选择性 H 拮抗剂 JNJ7777120、PLC 抑制剂 U73122 和 PKC 抑制剂 GF109203X 均可阻断槲皮素对组织胺诱导的[Ca]i升高的抑制作用。我们还发现 H4 激动剂(4-甲基组氨酸)诱导的[Ca]i升高可被槲皮素抑制。此外，选择性 TRPV1 阻断剂辣椒素显著抑制了槲皮素介导的组织胺诱导的[Ca]i升高的抑制作用，而 TRPV4 阻断剂 GSK2193874 则没有作用。最后，槲皮素降低了角质形成细胞中组织胺和 H4 激动剂诱导的 IL-8 表达，并抑制了 BALB/c 小鼠中化合物 48/80 诱导的搔抓行为。分子对接研究还表明，槲皮素与 H4 受体具有高结合亲和力(自动对接评分 H4=-8.7 kcal/mol)。这些数据表明，槲皮素可以通过 TRPV1 通道减少组织胺 4 受体诱导的钙内流，并为槲皮素在止痒、抗炎和不愉快感觉中的作用提供了分子机制。
