Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States.
Department of Ophthalmology, Beijing Hospital, National Center of Gerontology, Dong Dan, Beijing, People's Republic of China.
Invest Ophthalmol Vis Sci. 2018 Mar 1;59(3):1191-1198. doi: 10.1167/iovs.17-23067.
Neutrophil-secreted effector molecules are one of the primary causes of tissue damage during corneal inflammation. In the present study, we have investigated the effect of stromal cells in regulating neutrophil expression of tissue-damaging enzymes, myeloperoxidase (MPO), and N-elastase (ELANE).
Bone marrow-purified nonhematopoietic mesenchymal stromal cells and formyl-methionyl-leucyl-phenylalanine-activated neutrophils were cocultured in the presence or absence of Transwell inserts for 1 hour. Neutrophil effector molecules, MPO and ELANE, were quantified using ELISA. In mice, corneal injury was created by mechanical removal of the corneal epithelium and anterior stroma approximating one third of total corneal thickness, and mesenchymal stromal cells were then intravenously injected 1 hour post injury. Corneas were harvested to evaluate MPO expression and infiltration of CD11b+Ly6G+ neutrophils.
Activated neutrophils cocultured with mesenchymal stromal cells showed a significant 2-fold decrease in secretion of MPO and ELANE compared to neutrophils activated alone (P < 0.05). This suppressive effect was cell-cell contact dependent, as stromal cells cocultured with neutrophils in the presence of Transwell failed to suppress the secretion of neutrophil effector molecules. Following corneal injury, stromal cell-treated mice showed a significant 40% decrease in MPO expression by neutrophils and lower neutrophil frequencies compared to untreated injured controls (P < 0.05). Reduced MPO expression by neutrophils was also accompanied by normalization of corneal tissue structure following stromal cell treatment.
Mesenchymal stromal cells inhibit neutrophil effector functions via direct cell-cell contact interaction during inflammation. The current findings could have implications for the treatment of inflammatory ocular disorders caused by excessive neutrophil activation.
中性粒细胞分泌的效应分子是角膜炎症过程中组织损伤的主要原因之一。在本研究中，我们研究了基质细胞对调节中性粒细胞表达组织破坏性酶——髓过氧化物酶（MPO）和 N-弹性蛋白酶（ELANE）的作用。
将骨髓纯化的非造血间充质基质细胞和甲酰基-甲硫氨酸-亮氨酸-苯丙氨酸激活的中性粒细胞在存在或不存在 Transwell 插入物的情况下共培养 1 小时。使用 ELISA 定量中性粒细胞效应分子 MPO 和 ELANE。在小鼠中，通过机械去除角膜上皮和前基质来创建角膜损伤，近似于总角膜厚度的三分之一，然后在损伤后 1 小时静脉注射间充质基质细胞。收获角膜以评估 MPO 表达和 CD11b+Ly6G+中性粒细胞浸润。
与单独激活的中性粒细胞相比，与间充质基质细胞共培养的激活中性粒细胞 MPO 和 ELANE 的分泌显著降低了 2 倍（P < 0.05）。这种抑制作用依赖于细胞-细胞接触，因为在 Transwell 存在下与中性粒细胞共培养的基质细胞未能抑制中性粒细胞效应分子的分泌。角膜损伤后，与未处理的损伤对照相比，基质细胞处理的小鼠中性粒细胞的 MPO 表达显著降低了 40%（P < 0.05）。中性粒细胞 MPO 表达的减少也伴随着基质细胞处理后角膜组织结构的正常化。
间充质基质细胞通过炎症过程中的直接细胞-细胞接触相互作用抑制中性粒细胞效应功能。这些发现可能对治疗由过度中性粒细胞激活引起的炎症性眼部疾病具有重要意义。
