BACKGOUND Vascular smooth muscle cells (VSMCs) transdifferentiated ectopically trigger vascular calcifications, contributing to clinical cardiovascular disease in the aging population. AnxA5 and TNAP play a crucial role in (patho)physiological mineralization. METHODS We performed affinity studies between DPPC and 9:1 DPPC:DPPS-proteoliposomes carrying AnxA5 and/or TNAP and different types of collagen matrix: type I, II, I + III and native collagenous extracellular matrix (ECM) produced from VSMCs with or without differentiation, to simulate ectopic calcification conditions. RESULTS AnxA5-proteoliposomes had the highest affinity for collagens, specially for type II. TNAP-proteoliposomes bound poorly and the simultaneous presence of TNAP in the AnxA5-proteoliposomes disturbed interactions between AnxA5 and collagen. DPPC AnxA5-proteoliposomes affinities for ECM from transdifferentiating cells went up 2-fold compared to that from native VSMCs. The affinities of DPPC:DPPS-proteoliposomes were high for ECM from VSMCs with or without differentiation, underscoring a synergistic effect between AnxA5 and DPPS. Co-localization studies uncovered binding of proteoliposomes harboring AnxA5 or TNAP+AnxA5 to various regions of the ECM, not limited to type II collagen. CONCLUSION AnxA5-proteoliposomes showed the highest affinities for type II collagen, deposited during chondrocyte mineralization in joint cartilage. TNAP in the lipid/protein microenvironment disturbs interactions between AnxA5 and collagen. These findings support the hypothesis that TNAP is cleaved from the MVs membrane just before ECM binding, such facilitating MV anchoring to ECM via AnxA5 interaction. GENERAL SIGNIFICANCE Proteoliposomes as MV biomimetics are useful in the understanding of mechanisms that regulate the mineralization process and may be essential for the development of novel therapeutic strategies to prevent or inhibit ectopic mineralization.

中文翻译：

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含有膜联蛋白 A5 和碱性磷酸酶的基质囊泡仿生物与通过矿化血管平滑肌细胞产生的天然胶原基质结合。

背景 血管平滑肌细胞 (VSMCs) 异位转分化引发血管钙化，导致老年人群的临床心血管疾病。AnxA5 和 TNAP 在（病理）生理矿化中起关键作用。方法我们在 DPPC 和 9:1 DPPC 之间进行了亲和力研究：携带 AnxA5 和/或 TNAP 的 DPPS-蛋白脂质体和不同类型的胶原蛋白基质：I、II、I + III 型和由具有或无需分化，模拟异位钙化条件。结果 AnxA5-proteoliposomes 对胶原蛋白具有最高的亲和力，特别是对 II 型胶原蛋白。TNAP-proteoliposomes 结合很差，并且 AnxA5-proteoliposomes 中 TNAP 的同时存在干扰了 AnxA5 和胶原蛋白之间的相互作用。与天然 VSMC 相比，DPPC AnxA5-蛋白脂质体对来自转分化细胞的 ECM 的亲和力增加了 2 倍。DPPC:DPPS-蛋白脂质体对来自有或没有分化的 VSMC 的 ECM 的亲和力很高，强调了 AnxA5 和 DPPS 之间的协同作用。共定位研究揭示了携带 AnxA5 或 TNAP+AnxA5 的蛋白脂质体与 ECM 的各个区域的结合，不仅限于 II 型胶原蛋白。结论 AnxA5-蛋白脂质体对 II 型胶原蛋白显示出最高的亲和力，在关节软骨的软骨细胞矿化过程中沉积。脂质/蛋白质微环境中的 TNAP 会干扰 AnxA5 和胶原蛋白之间的相互作用。这些发现支持了 TNAP 在 ECM 结合之前从 MVs 膜上裂解下来的假设，这样有助于 MV 通过 AnxA5 相互作用锚定到 ECM。