Depatment of Medicine, University of Vermont Larner College of Medicine, 149 Beaumont Ave, Burlington, VT, 05405, USA.
Complex Systems Center, University of Vermont, Burlington, VT, USA.
Sci Rep. 2021 Aug 17;11(1):16654. doi: 10.1038/s41598-021-95911-w.
Fibrotic diseases are characterized by progressive and often irreversible scarring of connective tissue in various organs, leading to substantial changes in tissue mechanics largely as a result of alterations in collagen structure. This is particularly important in the lung because its bulk modulus is so critical to the volume changes that take place during breathing. Nevertheless, it remains unclear how fibrotic abnormalities in the mechanical properties of pulmonary connective tissue can be linked to the stiffening of its individual collagen fibers. To address this question, we developed a network model of randomly oriented collagen and elastin fibers to represent pulmonary alveolar wall tissue. We show that the stress-strain behavior of this model arises via the interactions of collagen and elastin fiber networks and is critically dependent on the relative fiber stiffnesses of the individual collagen and elastin fibers themselves. We also show that the progression from linear to nonlinear stress-strain behavior of the model is associated with the percolation of stress across the collagen fiber network, but that the location of the percolation threshold is influenced by the waviness of collagen fibers.
纤维化疾病的特征是各种器官中结缔组织的进行性和经常不可逆转的瘢痕形成，导致组织力学发生实质性变化，主要是由于胶原结构的改变。这在肺部尤为重要，因为其体积模量对于呼吸过程中发生的体积变化至关重要。然而，纤维化如何使肺结缔组织的机械特性异常与个别胶原纤维的僵化相关联仍不清楚。为了解决这个问题，我们开发了一个随机取向的胶原和弹性纤维的网络模型，以代表肺泡壁组织。我们表明，该模型的应力-应变行为是通过胶原和弹性纤维网络的相互作用产生的，并且与个别胶原和弹性纤维本身的相对纤维刚度密切相关。我们还表明，模型从线性到非线性的应力-应变行为的进展与胶原纤维网络中的应力渗流有关，但渗流阈值的位置受胶原纤维的波浪度影响。
