Guedj Kevin, Khallou-Laschet Jamila, Clement Marc, Morvan Marion, Delbosc Sandrine, Gaston Anh-Thu, Andreata Francesco, Castier Yves, Deschildre Catherine, Michel Jean-Baptiste, Caligiuri Giuseppina, Nicoletti Antonino
Unité 1148, Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Xavier Bichat, Paris, France; Université Denis Diderot, Paris VII, Paris, France.
Unité 1148, Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Xavier Bichat, Paris, France.
PLoS One. 2014 Dec 30;9(12):e116295. doi: 10.1371/journal.pone.0116295. eCollection 2014.
Experimental atherosclerosis is characterized by the formation of tertiary lymphoid structures (TLOs) within the adventitial layer, which involves the chemokine-expressing aortic smooth muscle cells (SMCs). TLOs have also been described around human atherothrombotic arteries but the mechanisms of their formation remain poorly investigated. Herein, we tested whether human vascular SMCs play the role of chemokine-expressing cells that would trigger the formation of TLOs in atherothrombotic arteries.
We first characterized, by flow cytometry and immunofluorescence analysis, the prevalence and cell composition of TLOs in human abdominal aneurysms of the aorta (AAAs), an evolutive form of atherothrombosis. Chemotaxis experiments revealed that the conditioned medium from AAA tissues recruited significantly more B and T lymphocytes than the conditioned medium from control (N-AAA) tissues. This was associated with an increase in the concentration of CXCL13, CXCL16, CCL19, CCL20, and CCL21 chemokines in the conditioned medium from AAA tissues. Immunofluorescence analysis of AAA cryosections revealed that α-SMA-positive SMCs were the main contributors to the chemokine production. These results were confirmed by RT-qPCR assays where we found that primary vascular SMCs from AAA tissues expressed significantly more chemokines than SMCs from N-AAA. Finally, in vitro experiments demonstrated that the inflammatory cytokines found to be increased in the conditioned medium from AAA were able to trigger the production of chemokines by primary SMCs.
Together, these results suggest that human vascular SMCs in atherothrombotic arteries, in response to inflammatory signals, are converted into chemokine-expressing cells that trigger the recruitment of immune cells and the formation of aortic TLOs.
实验性动脉粥样硬化的特征是在外膜层形成三级淋巴结构（TLOs），这涉及表达趋化因子的主动脉平滑肌细胞（SMCs）。在人类动脉粥样硬化血栓形成动脉周围也发现了TLOs，但其形成机制仍未得到充分研究。在此，我们测试了人类血管平滑肌细胞是否发挥表达趋化因子的细胞的作用，从而触发动脉粥样硬化血栓形成动脉中TLOs的形成。
我们首先通过流式细胞术和免疫荧光分析，对人类腹主动脉瘤（AAAs）（一种动脉粥样硬化血栓形成的演变形式）中TLOs的发生率和细胞组成进行了表征。趋化实验表明，AAA组织的条件培养基比对照（N-AAA）组织的条件培养基招募了显著更多的B和T淋巴细胞。这与AAA组织条件培养基中CXCL13、CXCL16、CCL19、CCL20和CCL21趋化因子浓度的增加有关。AAA冰冻切片的免疫荧光分析显示，α-SMA阳性平滑肌细胞是趋化因子产生的主要贡献者。RT-qPCR分析证实了这些结果，我们发现AAA组织的原代血管平滑肌细胞比N-AAA的平滑肌细胞表达显著更多的趋化因子。最后，体外实验表明，在AAA条件培养基中发现增加的炎性细胞因子能够触发原代平滑肌细胞产生趋化因子。
总之，这些结果表明，动脉粥样硬化血栓形成动脉中的人类血管平滑肌细胞在炎症信号的作用下，转化为表达趋化因子的细胞，从而触发免疫细胞的募集和主动脉TLOs的形成。
