State Key Laboratory for Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau Special Administrative Region, China.
School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China.
FASEB J. 2020 May;34(5):6920-6933. doi: 10.1096/fj.201903206R. Epub 2020 Apr 2.
The eicosanoid lipoxin A and aspirin-triggered 15-epi-lipoxin A (ATL) are potent anti-inflammatory agents. How their anti-inflammatory effects are mediated by receptors such as the formyl peptide receptor 2 (FPR2/ALX) remains incompletely understood. In the present study, fluorescent biosensors of FPR2/ALX were prepared and ATL-induced conformational changes were recorded. A biphasic dose curve consisting of a descending phase and an ascending phase was observed, with the descending phase corresponding to diminished FPR2 response such as Ca mobilization induced by the potent synthetic agonist WKYMVm. Preincubation of FPR2-expressing cells with 100 pM of ATL also lowered the threshold for WKYMVm to induce β-arrestin-2 membrane translocation, and inhibited WKYMVm-induced interleukin 8 secretion, suggesting signaling bias favoring anti-inflammatory activities. At 100 pM and above, ATL-induced receptor conformational changes resembling that of the WKYMVm along with a weak but measurable inhibition of forskolin-induced cAMP accumulation. However, no Ca mobilization was induced by ATL until its concentration reached 1 µM. Taken together, these results suggest a dual regulatory mechanism by which ATL exerts anti-inflammatory effects through FPR2/ALX.
二十碳烯酸脂质素 A 和阿司匹林触发的 15-epi- 脂氧素 A（ATL）是有效的抗炎药。它们的抗炎作用是如何通过受体介导的，如甲酰肽受体 2（FPR2/ALX），仍然不完全清楚。在本研究中，制备了 FPR2/ALX 的荧光生物传感器，并记录了 ATL 诱导的构象变化。观察到一个双相剂量曲线，由下降相和上升相组成，下降相对应于 FPR2 反应的减弱，如强合成激动剂 WKYMVm 诱导的 Ca 动员。用 100 pM 的 ATL 预先孵育表达 FPR2 的细胞也降低了 WKYMVm 诱导β-arrestin-2 膜易位的阈值，并抑制了 WKYMVm 诱导的白细胞介素 8 分泌，表明信号偏向有利于抗炎活性。在 100 pM 及以上，ATL 诱导的受体构象变化类似于 WKYMVm，并伴有微弱但可测量的抑制 forskolin 诱导的 cAMP 积累。然而，直到 ATL 的浓度达到 1 µM 时，才诱导 Ca 动员。总之，这些结果表明，ATL 通过 FPR2/ALX 发挥抗炎作用的双重调节机制。
