Alshehri Fahad S M, Whyte Claire S, Tuncay Ahmet, Williams Maria-Louise, Wilson Heather M, Mutch Nicola J
Aberdeen Cardiovascular & Diabetes Centre, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK.
Int J Mol Sci. 2021 Jun 19;22(12):6591. doi: 10.3390/ijms22126591.
Factor XIII (FXIII) is a transglutaminase that promotes thrombus stability by cross-linking fibrin. The cellular form, a homodimer of the A subunits, denoted FXIII-A, lacks a classical signal peptide for its release; however, we have shown that it is exposed on activated platelets. Here we addressed whether monocytes expose intracellular FXIII-A in response to stimuli. Using flow cytometry, we demonstrate that FXIII-A antigen and activity are up-regulated on human monocytes in response to stimulation by IL-4 and IL-10. Higher basal levels of the FXIII-A antigen were noted on the membrane of the monocytic cell line THP-1, but activity was significantly enhanced following stimulation with IL-4 and IL-10. In contrast, treatment with lipopolysaccharide did not upregulate exposure of FXIII-A in THP-1 cells. Quantification of the FXIII-A activity revealed a significant increase in THP-1 cells in total cell lysates following stimulation with IL-4 and IL-10. Following fractionation, the largest pool of FXIII-A was membrane associated. Monocytes were actively incorporated into the fibrin mesh of model thrombi. We found that stimulation of monocytes and THP-1 cells with IL-4 and IL-10 stabilized FXIII-depleted thrombi against fibrinolytic degradation, via a transglutaminase-dependent mechanism. Our data suggest that monocyte-derived FXIII-A externalized in response to stimuli participates in thrombus stabilization.
凝血因子 XIII（FXIII）是一种转谷氨酰胺酶，可通过交联纤维蛋白来促进血栓稳定性。细胞形式的 FXIII 是 A 亚基的同二聚体，称为 FXIII-A，其释放缺乏经典信号肽；然而，我们已经表明它在活化血小板上暴露。在此，我们探讨单核细胞是否会响应刺激而暴露细胞内的 FXIII-A。使用流式细胞术，我们证明，响应于白细胞介素-4（IL-4）和白细胞介素-10（IL-10）的刺激，人单核细胞上的 FXIII-A 抗原和活性上调。在单核细胞系 THP-1 的膜上观察到 FXIII-A 抗原的基础水平较高，但在用 IL-4 和 IL-10 刺激后活性显著增强。相反，用脂多糖处理不会上调 THP-1 细胞中 FXIII-A 的暴露。FXIII-A 活性的定量分析显示，在用 IL-4 和 IL-10 刺激后，THP-1 细胞的总细胞裂解物中活性显著增加。分级分离后，FXIII-A 的最大部分与膜相关。单核细胞被积极整合到模型血栓的纤维蛋白网中。我们发现，用 IL-4 和 IL-10 刺激单核细胞和 THP-1 细胞，通过转谷氨酰胺酶依赖性机制使 FXIII 缺陷型血栓抵抗纤维蛋白溶解降解而稳定。我们的数据表明，响应刺激而外化的单核细胞衍生的 FXIII-A 参与血栓稳定。
