Sensitivity of alveolar macrophages to substrate mechanical and adhesive properties
Sensitivity of alveolar macrophages to substrate mechanical and adhesive properties
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DOI：
10.1002/cm.20130
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发表时间：
2006-06-01
影响因子：
--
通讯作者：
Planus, Emmanuelle
中科院分区：
文献类型：
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作者：
Fereol, Sophie;Fodil, Redouane;Planus, Emmanuelle
为了了解肺泡巨噬细胞（AMs）对底物特性的敏感性，我们建立了一种新的巨噬细胞模型，培养在增加杨氏模量的底物上：(i)单层肺泡上皮细胞代表柔软（类似于0.1千帕）的生理底物，（ii）聚丙烯酰胺凝胶含有两种浓度的双丙烯酰胺，代表低和高中间刚度（分别为40千帕和160千帕），（iii）塑料或玻璃的高刚性表面（分别为3兆帕和70兆帕），后两者被或不被i型胶原功能化。通过巨噬细胞的形状（以f -肌动蛋白结构的3d重建为特征）和细胞骨架刚度（通过磁性rgd涂层珠的瞬时扭转估计，并根据实际珠浸入进行校正）来研究巨噬细胞的反应。随着底物刚度从软底物(i)和（ii）增加到硬底物（iii），巨噬细胞的形状从圆形急剧变为扁平，表明肺泡巨噬细胞对底物刚度的净敏感性，但不产生f -肌动蛋白应力纤维。巨噬细胞硬度也随着底物硬度的大幅增加而增加，但这种增加不是由于内部张力的增加，通过f -肌动蛋白解聚药物（细胞chalasine D）对头部扭转的可忽略不计的影响来评估。AMs的机械灵敏度可以部分解释为一个理想化的数值模型，该模型描述了低单元高度如何增强表面（测量）AM刚度对基板刚度的依赖性。总之，这些结果表明巨噬细胞能够探测其物理环境，但其机械敏感机制似乎与组织细胞大不相同，因为它发生在没有显著的细胞尺度预应力的情况下，通过最小的肌动蛋白重塑改变形状，最终AMs刚度不受f -肌动蛋白完整性损失的影响。
In order to understand the sensitivity of alveolar macrophages (AMs) to substrate properties, we have developed a new model of macrophages cultured on substrates of increasing Young's modulus: (i) a monolayer of alveolar epithelial cells representing the supple (similar to 0.1 kPa) physiological substrate, (ii) polyacrylamide gels with two concentrations of bis-acrylamide representing low and high intermediate stiffness (respectively 40 kPa and 160 kPa) and, (iii) a highly rigid surface of plastic or glass (respectively 3 MPa and 70 MPa), the two latter being or not functionalized with type I-collagen. The macrophage response was studied through their shape (characterized by 3D-reconstructions of F-actin structure) and their cytoskeletal stiffness (estimated by transient twisting of magnetic RGD-coated beads and corrected for actual bead immersion). Macrophage shape dramatically changed from rounded to flattened as substrate stiffness increased from soft ((i) and (ii)) to rigid (iii) substrates, indicating a net sensitivity of alveolar macrophages to substrate stiffness but without generating F-actin stress fibers. Macrophage stiffness was also increased by large substrate stiffness increase but this increase was not due to an increase in internal tension assessed by the negligible effect of a F-actin depolymerizing drug (cytochalasine D) on bead twisting. The mechanical sensitivity of AMs could be partly explained by an idealized numerical model describing how low cell height enhances the substrate-stiffness-dependence of the apparent (measured) AM stiffness. Altogether, these results suggest that macrophages are able to probe their physical environment but the mechanosensitive mechanism behind appears quite different from tissue cells, since it occurs at no significant cell-scale prestress, shape changes through minimal actin remodeling and finally an AMs stiffness not affected by the loss in F-actin integrity.