BioMedicine Design, Pfizer, Cambridge, Massachusetts, United States of America.
Inflammation and Immunology, Pfizer, Cambridge, Massachusetts, United States of America.
PLoS One. 2023 Jan 20;18(1):e0280590. doi: 10.1371/journal.pone.0280590. eCollection 2023.
C-C motif chemokine receptor-like 2 (CCRL2) is a non-signaling 7 transmembrane receptor that binds chemotactic ligands to shape leukocyte recruitment to sites of inflammation. However, there is a lack of consensus on the ligands that directly bind CCRL2 or their functional impact. Studies with CCRL2 knockout mice have demonstrated that neutrophils have impaired degranulation and migration in response to CXCL8, where the underlying molecular mechanism is proposed to be due to the formation of CCRL2 heterodimers with the chemokine receptor CXCR2. Herein, we characterized the ligands that bind directly to CCRL2 and interrogated the impact of CCRL2 neutralization on CXCL8 signaling in neutrophils using pharmacological antibody tools. Using flow cytometry and Surface Plasmon Resonance microscopy (SPRm) cell binding experiments, we confirmed that chemerin, but not previously reported C-C chemokines, binds CCRL2. Furthermore, we identified human and mouse CCRL2 antibodies that neutralized chemerin binding to CCRL2. Unexpectedly, we found that neutralization of CCRL2 with these antibodies did not attenuate CXCL8-induced human neutrophil degranulation nor CXCL8-induced murine neutrophil recruitment to the peritoneum. Based on the observed differences in modulating CCRL2 function with neutralizing antibodies compared to the reported CCRL2 deficient murine models, we hypothesize that the ligand binding function of CCRL2 is dispensable for CXCL8 signaling in neutrophils. Finally, extensive profiling of CCRL2 expression on peripheral blood leukocytes revealed monocytes, dendritic cells (DC), and subpopulations of natural killer T (NKT) cells as additional targets, highlighting potential roles for CCRL2 in human cell types beyond neutrophils that warrants future investigation.
C-C 基序趋化因子受体样 2(CCRL2)是一种非信号转导的 7 跨膜受体,它结合趋化因子配体来塑造白细胞向炎症部位的募集。然而,对于直接与 CCRL2 结合的配体及其功能影响,目前还没有共识。CCRL2 敲除小鼠的研究表明,中性粒细胞在响应 CXCL8 时脱颗粒和迁移受损,其潜在的分子机制被认为是由于 CCRL2 与趋化因子受体 CXCR2 形成异二聚体。在此,我们对直接与 CCRL2 结合的配体进行了表征,并使用药理学抗体工具研究了 CCRL2 中和对中性粒细胞中 CXCL8 信号的影响。通过流式细胞术和表面等离子体共振显微镜(SPRm)细胞结合实验,我们证实了趋化素而非先前报道的 C-C 趋化因子与 CCRL2 结合。此外,我们鉴定了中和趋化素与 CCRL2 结合的人源和鼠源 CCRL2 抗体。出乎意料的是,我们发现用这些抗体中和 CCRL2 并不能减弱 CXCL8 诱导的人中性粒细胞脱颗粒,也不能减弱 CXCL8 诱导的鼠中性粒细胞募集到腹膜腔。基于与报道的 CCRL2 缺陷型小鼠模型相比,用中和抗体调节 CCRL2 功能的观察到的差异,我们假设 CCRL2 的配体结合功能对于中性粒细胞中 CXCL8 信号是可有可无的。最后,对外周血白细胞中 CCRL2 表达的广泛分析显示单核细胞、树突状细胞(DC)和自然杀伤 T(NKT)细胞的亚群是其他靶点,突出了 CCRL2 在除中性粒细胞以外的人类细胞类型中的潜在作用,值得进一步研究。