Primordial GATA6 macrophages function as extravascular platelets in sterile injury

Most multicellular organisms have a major body cavity that harbors immune
cells. In primordial species like purple sea urchins, these cells perform
phagocytic functions but are also crucial in repairing injuries. In
mammals, the peritoneal cavity contains large numbers of resident GATA6+
macrophages, which may play a similar role. It is unclear how cavity
macrophages suspended in the fluid phase (peritoneal fluid) identify and
migrate towards injuries, however. Here, we show that cavity macrophages
in fluid rapidly form thrombus-like structures in response to injury using
primordial scavenger receptor (SRCR) domains. Aggregates of cavity
macrophages physically sealed injuries and promoted rapid repair of focal
lesions. In iatrogenic surgical situations, these cavity macrophages
formed extensive aggregates that promoted the growth of intra-abdominal
scar tissue termed peritoneal adhesions.

多数多细胞生物均拥有一处核心体腔，其内寄居着免疫细胞。在紫海胆这类原始物种中，此类细胞不仅具备吞噬功能，同时在损伤修复过程中发挥关键作用。在哺乳动物体内，腹膜腔中存在大量驻留型GATA6+巨噬细胞，其或许承担着相似的功能。但目前尚不清楚，悬浮于体液相（即腹膜液）中的体腔巨噬细胞是如何识别损伤并向损伤部位迁移的。本研究表明，流体中的体腔巨噬细胞可通过原始清道夫受体（scavenger receptor, SRCR）结构域，在感知损伤后快速形成血栓样聚集结构。这类体腔巨噬细胞聚集物可物理性封闭损伤位点，并促进局灶性损伤的快速修复。在医源性手术场景中，此类体腔巨噬细胞会形成大规模聚集，进而促进被称为腹膜粘连的腹腔瘢痕组织增生。