FPR2/ALX 受体的表达和内化对于脂氧素 A4 和 annexin 衍生肽刺激的吞噬作用至关重要。
FPR2/ALX receptor expression and internalization are critical for lipoxin A4 and annexin-derived peptide-stimulated phagocytosis.
机构信息
UCD Diabetes Research Centre, UCD School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
出版信息
FASEB J. 2010 Nov;24(11):4240-9. doi: 10.1096/fj.10-159913. Epub 2010 Jun 22.
Lipoxins (LXs) are endogenously produced eicosanoids with well-described anti-inflammatory and proresolution activities, stimulating nonphlogistic phagocytosis of apoptotic cells by macrophages. LXA(4) and the glucocorticoid-derived annexin A1 peptide (Ac2-26) bind to a common G-protein-coupled receptor, termed FPR2/ALX. However, direct evidence of the involvement of FPR2/ALX in the anti-inflammatory and proresolution activity of LXA(4) is still to be investigated. Here we describe FPR2/ALX trafficking in response to LXA(4) and Ac2-26 stimulation. We have transfected cells with HA-tagged FPR2/ALX and studied receptor trafficking in unstimulated, LXA(4) (1-10 nM)- and Ac2-26 (30 μM)-treated cells using multiple approaches that include immunofluorescent confocal microscopy, immunogold labeling of cryosections, and ELISA and investigated receptor trafficking in agonist-stimulated phagocytosis. We conclude that PKC-dependent internalization of FPR2/ALX is required for phagocytosis. Using bone marrow-derived macrophages (BMDMs) from mice in which the FPR2/ALX ortholog Fpr2 had been deleted, we observed the nonredundant function for this receptor in LXA(4) and Ac2-26 stimulated phagocytosis of apoptotic neutrophils. LXA(4) stimulated phagocytosis 1.7-fold above basal (P<0.001) by BMDMs from wild-type mice, whereas no effect was found on BMDMs from Fpr2(-/-) mice. Similarly, Ac2-26 stimulates phagocytosis by BMDMs from wild-type mice 1.5-fold above basal (P<0.05). However, Ac2-26 failed to stimulate phagocytosis by BMDMs isolated from Fpr2(-/-) mice relative to vehicle. These data reveal novel and complex mechanisms of the FPR2/ALX receptor trafficking and functionality in the resolution of inflammation.
脂氧素(LXs)是内源性产生的具有明确抗炎和促解决作用的二十烷类物质,刺激巨噬细胞吞噬非炎症性凋亡细胞。LXA(4)和糖皮质激素衍生的膜联蛋白 A1 肽(Ac2-26)与一种共同的 G 蛋白偶联受体 FPR2/ALX 结合。然而,FPR2/ALX 参与 LXA(4)抗炎和促解决活性的直接证据仍有待研究。在这里,我们描述了 LXA(4)和 Ac2-26 刺激后 FPR2/ALX 的转运。我们用 HA 标记的 FPR2/ALX 转染细胞,并使用多种方法研究未刺激、LXA(4)(1-10 nM)和 Ac2-26(30 μM)处理的细胞中的受体转运,包括免疫荧光共焦显微镜、冷冻切片免疫金标记和 ELISA,并研究了激动剂刺激吞噬作用中的受体转运。我们得出结论,PKC 依赖性 FPR2/ALX 内化是吞噬作用所必需的。使用 FPR2/ALX 同源物 Fpr2 缺失的小鼠骨髓来源的巨噬细胞(BMDM),我们观察到该受体在 LXA(4)和 Ac2-26 刺激凋亡中性粒细胞吞噬中的非冗余功能。LXA(4)刺激 BMDM 吞噬作用比基础水平增加 1.7 倍(P<0.001),而 Fpr2(-/-)小鼠的 BMDM 则没有影响。同样,Ac2-26 刺激野生型小鼠 BMDM 的吞噬作用比基础水平增加 1.5 倍(P<0.05)。然而,Ac2-26 未能刺激 Fpr2(-/-)小鼠分离的 BMDM 的吞噬作用相对于载体。这些数据揭示了 FPR2/ALX 受体转运和功能在炎症解决中的新的和复杂的机制。