Justynski Olivia, Bridges Kate, Krause Will, Forni Maria Fernanda, Phan Quan, Sandoval-Schaefer Teresa, Driskell Ryan, Miller-Jensen Kathryn, Horsley Valerie
bioRxiv. 2023 Jan 17:2023.01.17.523241. doi: 10.1101/2023.01.17.523241.
Apoptosis and clearance of apoptotic cells via efferocytosis are evolutionarily conserved processes that drive tissue repair. However, the mechanisms by which recognition and clearance of apoptotic cells regulate repair are not fully understood. Here, we use single-cell RNA sequencing to provide a map of the cellular dynamics during early inflammation in mouse skin wounds. We find that apoptotic pathways and efferocytosis receptors are elevated in fibroblasts and immune cells, including resident Lyve1 macrophages, during inflammation. Interestingly, human diabetic foot wounds upregulate mRNAs for apoptotic genes and display increased and altered efferocytosis signaling via the receptor Axl. During early inflammation in mouse wounds, we detect upregulation of Axl in dendritic cells and fibroblasts via TLR3-independent mechanisms. Inhibition studies in mice reveal that Axl signaling is required for wound repair but is dispensable for efferocytosis. By contrast, inhibition of another efferocytosis receptor, Timd4, in mouse wounds decreases efferocytosis and abrogates wound repair. These data highlight the distinct mechanisms by which apoptotic cell detection coordinates tissue repair and provides potential therapeutic targets for chronic wounds in diabetic patients.
通过胞葬作用实现的细胞凋亡及凋亡细胞清除是驱动组织修复的进化保守过程。然而，凋亡细胞的识别与清除调控组织修复的机制尚未完全明确。在此，我们利用单细胞RNA测序绘制了小鼠皮肤伤口早期炎症过程中的细胞动态图谱。我们发现，在炎症期间，凋亡途径和胞葬作用受体在成纤维细胞和免疫细胞（包括常驻Lyve1巨噬细胞）中表达上调。有趣的是，人类糖尿病足伤口上调凋亡基因的mRNA，并通过受体Axl显示出胞葬作用信号的增加和改变。在小鼠伤口早期炎症期间，我们通过非TLR3依赖机制检测到树突状细胞和成纤维细胞中Axl的上调。小鼠体内的抑制研究表明，Axl信号传导是伤口修复所必需的，但对胞葬作用而言并非必需。相比之下，在小鼠伤口中抑制另一种胞葬作用受体Timd4会降低胞葬作用并消除伤口修复。这些数据突出了凋亡细胞检测协调组织修复的不同机制，并为糖尿病患者的慢性伤口提供了潜在的治疗靶点。
