Department of Pharmacology, Menarini Ricerche S.p.A., Florence, Italy.
Br J Pharmacol. 2011 Feb;162(3):611-22. doi: 10.1111/j.1476-5381.2010.01062.x.
In osteoarthritis (OA), bradykinin (BK) is known to contribute to pain and synovitis, but not to cartilage degradation. Here, we investigated effects of BK and its antagonists on chondrocytes, cells involved in cartilage homeostasis.
BK receptor density and affinities of BK, its analogues and antagonists were measured in cultured human and rat chondrocytes by radioligand binding. Effects of BK were assessed by accumulation of inositol phosphates (IP) and release of interleukin (IL)-6 and IL-8.
Density of [³H]-BK binding sites was higher (13-30-fold) and BK evoked a greater (48-fold) IP production, in human than in rat chondrocytes. The BK B₂ receptor antagonists MEN16132 and icatibant displayed similar binding affinity. MEN16132 was 40-fold more potent than icatibant in the IP assay. In human chondrocytes, BK increased release (over 24 h) of IL-6 and IL-8, effects blocked by MEN16132 but not by the B₁ receptor antagonist Lys-[Leu⁸][desArg⁹]BK. BK-induced release of IL-6, but not of IL-8, was partially inhibited by indomethacin (10 µM) and nordihydroguaiaretic acid (10 µM). Antagonists for the prostanoid EP receptors (AH6809 10 µM; L-798,196, 200 nM; L-161,982, 1 µM) were ineffective. Dexamethasone (100 nM) partially inhibited release of both IL-6 and IL-8. Inhibitors of intracellular downstream signalling pathways (SB203580 10 µM; PD98059, 30 µM; SP600125, 30 µM; BAY-117085, 5 µM) indicated the involvement of p38 MAPK and the activation of NF-κB.
BK mediated inflammatory changes and cartilage degradation and B₂ receptor blockade would, therefore, be a potential treatment for OA.
在骨关节炎（OA）中，缓激肽（BK）已知会导致疼痛和滑膜炎，但不会导致软骨降解。在这里，我们研究了 BK 及其拮抗剂对参与软骨稳态的软骨细胞的影响。
通过放射性配体结合测量培养的人源和大鼠源软骨细胞中 BK 受体的密度和亲和力，以及 BK、其类似物和拮抗剂的亲和力。通过肌醇磷酸（IP）的积累和白细胞介素（IL）-6 和 IL-8 的释放来评估 BK 的作用。
与大鼠软骨细胞相比，人源软骨细胞中 [³H]-BK 结合位点的密度更高（13-30 倍），BK 引起的 IP 产生更大（48 倍）。BK B₂ 受体拮抗剂 MEN16132 和 icatibant 具有相似的结合亲和力。在 IP 测定中，MEN16132 比 icatibant 强 40 倍。在人源软骨细胞中，BK 增加了白细胞介素（IL）-6 和 IL-8 的释放（超过 24 小时），该作用可被 MEN16132 阻断，但不能被 B₁ 受体拮抗剂 Lys-[Leu⁸][desArg⁹]BK 阻断。BK 诱导的 IL-6 释放，但不是 IL-8 释放，部分被吲哚美辛（10 µM）和 nordihydroguaiaretic acid（10 µM）抑制。前列腺素 EP 受体的拮抗剂（AH6809 10 µM；L-798,196，200 nM；L-161,982，1 µM）无效。地塞米松（100 nM）部分抑制了 IL-6 和 IL-8 的释放。细胞内下游信号通路的抑制剂（SB203580 10 µM；PD98059，30 µM；SP600125，30 µM；BAY-117085，5 µM）表明 p38 MAPK 的参与和 NF-κB 的激活。
BK 介导了炎症变化和软骨降解，因此 B₂ 受体阻断可能成为 OA 的一种潜在治疗方法。
