Department of Biomedical Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA, USA.
Biomater Sci. 2020 Apr 21;8(8):2289-2299. doi: 10.1039/c9bm01474h. Epub 2020 Mar 12.
Biomaterial implantation triggers an immune response initially predominated by neutrophils, which activate an inflammatory cascade by producing cytokines, enzymes, immune cell recruitment chemokines, and DNA fiber networks called neutrophil extracellular traps (NETs). While the role of neutrophils has been studied extensively in infection, little is known of their role in the response to biomaterials, in this case titanium (Ti) implants. Furthermore, while implant surface modifications have been shown to attenuate pro-inflammatory polarization in other immune cells, their effects on neutrophil behavior is unknown. The aim of this study was to characterize the neutrophil response to Ti surface topography and hydrophilicity and understand how the products of biomaterial-induced neutrophil activation alters macrophage polarization. Murine neutrophils were isolated by density gradient centrifugation and plated on smooth, rough, and rough hydrophilic (rough-hydro) Ti surfaces. Neutrophils on rough-hydro Ti decreased pro-inflammatory cytokine and enzyme production as well as decreased NET formation compared to neutrophils on smooth and rough Ti. Conditioned media (CM) from neutrophils on smooth Ti enhanced pro-inflammatory macrophage polarization compared to CM from neutrophils on rough or rough-hydro Ti; pretreatment of neutrophils with a pharmacological NETosis inhibitor impaired this macrophage stimulation. Finally, co-culture of neutrophils and macrophages on Ti surfaces induced pro-inflammatory macrophage polarization compared to macrophages alone on surfaces, but this effect was ablated when neutrophils were pretreated with the NETosis inhibitor. These findings demonstrate that neutrophils are sensitive to changes in biomaterial surface properties and exhibit differential activation in response to Ti surface cues. Additionally, inhibition of NETosis enhanced anti-inflammatory macrophage polarization, suggesting NETosis as a possible therapeutic target for enhancing implant integration.
生物材料植入会引发最初以中性粒细胞为主的免疫反应，中性粒细胞通过产生细胞因子、酶、免疫细胞募集趋化因子和称为中性粒细胞胞外诱捕网（NETs）的 DNA 纤维网络来激活炎症级联反应。虽然中性粒细胞在感染中的作用已经得到了广泛的研究，但对于它们在生物材料反应中的作用，尤其是在钛（Ti）植入物中的作用知之甚少。此外，虽然已经证明植入物表面改性可以减弱其他免疫细胞的促炎极化，但它们对中性粒细胞行为的影响尚不清楚。本研究旨在表征中性粒细胞对 Ti 表面形貌和亲水性的反应，并了解生物材料诱导的中性粒细胞激活产物如何改变巨噬细胞极化。通过密度梯度离心分离小鼠中性粒细胞，并在光滑、粗糙和粗糙亲水（rough-hydro）Ti 表面上进行培养。与在光滑和粗糙 Ti 上的中性粒细胞相比，在 rough-hydro Ti 上的中性粒细胞减少了促炎细胞因子和酶的产生以及 NET 的形成。与在粗糙或 rough-hydro Ti 上的中性粒细胞相比，来自光滑 Ti 上的中性粒细胞的条件培养基（CM）增强了促炎巨噬细胞的极化；用药理学 NETosis 抑制剂预处理中性粒细胞会损害这种巨噬细胞刺激。最后，与单独在表面上培养的巨噬细胞相比，中性粒细胞和巨噬细胞在 Ti 表面上的共培养诱导了促炎巨噬细胞的极化，但当用 NETosis 抑制剂预处理中性粒细胞时，这种效应被消除。这些发现表明，中性粒细胞对生物材料表面性质的变化敏感，并对 Ti 表面线索表现出不同的激活。此外，NETosis 的抑制增强了抗炎性巨噬细胞的极化，表明 NETosis 可能是增强植入物整合的潜在治疗靶点。
