Rödel Franz, Hofmann Dorothée, Auer Judith, Keilholz Ludwig, Röllinghoff Martin, Sauer Rolf, Beuscher Horst Ulrich
Department of Radiotherapy and Oncology, University of Frankfurt/Main, Germany.
Strahlenther Onkol. 2008 Jan;184(1):41-7. doi: 10.1007/s00066-008-1776-8.
Low-dose radiotherapy (LD-RT) is known to exert an anti-inflammatory effect, however, the underlying molecular mechanisms are not fully understood. The manipulation of polymorphonuclear neutrophil (PMN) function and/or recruitment may be one mechanism. Chemokines contribute to this process by creating a chemotactic gradient and by activating integrins. This study aimed to characterize the effect of LD-RT on CCL20 chemokine production and PMN/endothelial cell (EC) adhesion.
The EC line EA.hy.926 was irradiated with doses ranging from 0 to 3 Gy and was co-cultured with PMNs from healthy donors either by direct cell contact or separated by transwell membrane chambers. CXCL8, CCL18, CCL20 chemokine and tumor necrosis factor-(TNF-)alpha cytokine levels in supernatants were determined by ELISA and adhesion assays were performed. The functional impact of the cytokines transforming growth factor-(TGF-)beta(1) and TNF-alpha and of the intercellular adhesion molecule-(ICAM-)1 on CCL20 expression was analyzed by using neutralizing antibodies.
As compared to CXCL8 and CCL18, CCL20 chemokine secretion was found to be exclusively induced by a direct cell-cell contact between PMNs and EA.hy.926 ECs in a TNF-alpha-dependent, but ICAM-1-independent manner. Furthermore, irradiation with doses between 0.5 and 1 Gy resulted in a significant reduction of CCL20 release which was dependent on TGF-beta(1) (p < 0.01). The decrease of CCL20 paralleled with a significant reduction in PMN/EA.hy.926 EC adhesion (p < 0.001).
The modulation of CCL20 chemokine expression and PMN/EC adhesion adds a further facet to the plethora of mechanisms contributing to the anti-inflammatory efficacy of LD-RT.
已知低剂量放疗（LD-RT）具有抗炎作用，但其潜在分子机制尚未完全明确。多形核中性粒细胞（PMN）功能和/或募集的调控可能是其中一种机制。趋化因子通过形成趋化梯度和激活整合素来促成这一过程。本研究旨在明确LD-RT对CCL20趋化因子产生及PMN/内皮细胞（EC）黏附的影响。
用0至3 Gy的剂量照射EC系EA.hy.926，并通过直接细胞接触或经Transwell膜小室分隔与健康供体的PMN共培养。采用酶联免疫吸附测定法（ELISA）测定上清液中CXCL8、CCL18、CCL20趋化因子和肿瘤坏死因子-α（TNF-α）细胞因子水平，并进行黏附试验。使用中和抗体分析细胞因子转化生长因子-β（TGF-β）1、TNF-α及细胞间黏附分子-1（ICAM-1）对CCL20表达的功能影响。
与CXCL8和CCL18相比，发现CCL20趋化因子分泌仅由PMN与EA.hy.926 EC之间的直接细胞接触以TNF-α依赖但ICAM-1非依赖的方式诱导产生。此外，0.5至1 Gy剂量的照射导致CCL20释放显著减少，这依赖于TGF-β1（p < 0.01）。CCL20的减少与PMN/EA.hy.926 EC黏附的显著降低平行（p < 0.001）。
CCL20趋化因子表达及PMN/EC黏附的调节为LD-RT抗炎功效的众多机制增添了新的方面。
