PDF(Pubmed)
Abstract：
Secreted chemokines form concentration gradients in target tissues to control migratory directions and patterns of immune cells in response to inflammatory stimulation; however, how the gradients are formed is much debated. Heparan sulfate (HS) binds to chemokines and modulates their activities. In this study, we investigated the roles of HS in the gradient formation and chemoattractant activity of CCL5 that is known to bind to HS. CCL5 and heparin underwent liquid-liquid phase separation and formed gradient, which was confirmed using CCL5 immobilized on heparin-beads. The biological implication of HS in CCL5 gradient formation was established in CHO-K1 (wild-type) and CHO-677 (lacking HS) cells by Transwell assay. The effect of HS on CCL5 chemoattractant activity was further proved by Transwell assay of human peripheral blood cells. Finally, peritoneal injection of the chemokines into mice showed reduced recruitment of inflammatory cells either by mutant CCL5 (lacking heparin-binding sequence) or by addition of heparin to wild-type CCL5. Our experimental data propose that co-phase separation of CCL5 with HS establishes a specific chemokine concentration gradient to trigger directional cell migration. The results warrant further investigation on other heparin-binding chemokines and allows for a more elaborate insight into disease process and new treatment strategies.
摘要：
分泌的趋化因子在靶组织中形成浓度梯度，以控制免疫细胞响应炎症刺激的迁移方向和模式；然而，梯度是如何形成的还有很多争议。硫酸乙酰肝素(HS)与趋化因子结合并调节其活性。在这项研究中,我们研究了HS在已知与HS结合的CCL5的梯度形成和化学引诱物活性中的作用。CCL5与肝素进行液-液相分离,形成梯度,使用固定在肝素珠上的CCL5证实了这一点。通过Transwell测定，在CHO-K1（野生型）和CHO-677（缺乏HS）细胞中建立了HS在CCL5梯度形成中的生物学意义。人外周血细胞的Transwell测定进一步证明了HS对CCL5化学引诱物活性的影响。最后,通过突变CCL5(缺乏肝素结合序列)或通过向野生型CCL5添加肝素,向小鼠腹膜注射趋化因子显示炎性细胞募集减少。我们的实验数据表明，CCL5与HS的共相分离建立了特定的趋化因子浓度梯度以触发定向细胞迁移。结果值得对其他肝素结合趋化因子进行进一步研究，并可以更详细地了解疾病过程和新的治疗策略。
