■作为身体抵御疾病和感染的第一道防线,中性粒细胞必须有效地导航到炎症部位;然而,中性粒细胞失调有助于许多疾病的发病机制,使人们容易感染。这些疾病中的许多也与细胞外基质的蛋白质组成的变化有关。虽然已知嗜中性粒细胞和内皮细胞,在中性粒细胞激活中起关键作用,对细胞外基质的机械和结构特性敏感,我们对基质中的蛋白质成分如何影响中性粒细胞对感染的反应的理解是不完全的.
■为了研究细胞外基质成分对中性粒细胞感染反应的影响,我们使用了一种芯片上感染的微流控装置,该装置复制了被模型细胞外基质包围的血管内皮的一部分.通过在2、4或6mg/mL的I型胶原水凝胶上接种人脐静脉内皮细胞来制造模型血管。将原代人嗜中性粒细胞加载到内皮腔中并通过将细菌病原体铜绿假单胞菌添加到周围基质来刺激。
■胶原蛋白浓度不影响内皮细胞腔的细胞密度或屏障功能。在传染性挑战下,我们发现,与6mg/mL胶原凝胶相比,4mg/mL胶原凝胶中的中性粒细胞外渗更多.我们进一步发现,外渗的嗜中性粒细胞在2mg/mL凝胶中具有最高的迁移速度和距离,并且这些值随着胶原蛋白浓度的增加而降低。然而,这些现象在没有内皮腔的情况下没有观察到.最后,在不同的胶原浓度下,未观察到产生活性氧的嗜中性粒细胞外渗百分比的差异.
■我们的研究表明,中性粒细胞外渗和迁移对感染性攻击的反应受胶原蛋白浓度以内皮细胞依赖性方式调节。结果证明了组织微环境的机械和结构方面如何影响嗜中性粒细胞对感染的反应。此外,这些发现强调了开发和使用微生理系统来研究控制中性粒细胞反应的调节因子的重要性.
UNASSIGNED: As the body\'s first line of defense against disease and infection, neutrophils must efficiently navigate to sites of inflammation; however, neutrophil dysregulation contributes to the pathogenesis of numerous diseases that leave people susceptible to infections. Many of these diseases are also associated with changes to the protein composition of the extracellular matrix. While it is known that neutrophils and endothelial cells, which play a key role in neutrophil activation, are sensitive to the mechanical and structural properties of the extracellular matrix, our understanding of how protein composition in the matrix affects the neutrophil response to infection is incomplete.
UNASSIGNED: To investigate the effects of extracellular matrix composition on the neutrophil response to infection, we used an infection-on-a-chip microfluidic device that replicates a portion of a blood vessel endothelium surrounded by a model extracellular matrix. Model blood vessels were fabricated by seeding human umbilical vein endothelial cells on 2, 4, or 6 mg/mL type I collagen hydrogels. Primary human neutrophils were loaded into the endothelial lumens and stimulated by adding the bacterial pathogen Pseudomonas aeruginosa to the surrounding matrix.
UNASSIGNED: Collagen concentration did not affect the cell density or barrier function of the endothelial lumens. Upon infectious challenge, we found greater neutrophil extravasation into the 4 mg/mL collagen gels compared to the 6 mg/mL collagen gels. We further found that extravasated neutrophils had the highest migration speed and distance in 2mg/mL gels and that these values decreased with increasing collagen concentration. However, these phenomena were not observed in the absence of an endothelial lumen. Lastly, no differences in the percent of extravasated neutrophils producing reactive oxygen species were observed across the various collagen concentrations.
UNASSIGNED: Our study suggests that neutrophil extravasation and migration in response to an infectious challenge are regulated by collagen concentration in an endothelial cell-dependent manner. The results demonstrate how the mechanical and structural aspects of the tissue microenvironment affect the neutrophil response to infection. Additionally, these findings underscore the importance of developing and using microphysiological systems for studying the regulatory factors that govern the neutrophil response.