Microglial Piezo1-mediated mechanotransduction play an important role in activation of neurotoxic reactive astrocyte in experimental glaucoma

Background: Previous studies indicated that activation of glial cells and inflammatory responses are triggering factors of glaucomatous optic neuropathy. In particular, neurotoxic reactive astrocytes have been found to play a significant role in retinal ganglion cell damage. Furthermore, research showed that activation of glial cells is not dependent on retinal ganglion cell injury, but rather a direct response to pathological elevation of intraocular pressure (IOP). However, the molecular mechanism by which elevated IOP triggers glial activation through mechanical forces remains unknown. Main body: We constructed a high IOP animal model by injecting Matrigel hydrogel into the anterior chamber of rats. The spatial transcriptomic sequencing and bioinfomation analysis were performed using tissues from the high IOP rats and control rats. Subsequently, mechanical intervention was given to cultured microglia in vitro, and the conditioned medium after intervention was applied to astrocytes to explorethe interaction between microglia and astrocytes under mechanical stimulation, and QPCR and Western Blot examinations were used to analyze the changes in secretory factors of microglia under mechanical stimulation. The role of piezo1 as a mechanical receptor in microglia was further clarified by activating or inhibiting piezo1 in the cultured microglia under mechanical stimulation. By spatial transcriptome sequencing, we determined for the first time in vivo that glial cells in optic nerve head were rapidly activated, and the neurotoxic reactive astrocyte were induced under high IOP. Subsequently, we demonstrated that microglial culture medium after mechanical intervention can significantly promote the transformation of astrocytes into neurotoxic astrocytes, and the key regulatory factors are inflammatory factors such as IL-1α and TNF-α. In addition, we found that microglia activate and up-regulate the expression of these inflammatory factors by sensing mechanical stimulation mainly through piezo1. Conclusions: Our study revealed that the neurotoxic astrocyte would rapidly be reactivated in the optic nerve head under elevated intraocular pressure in vivo. Additionally, we found that microglia could be activated by directly sensing mechanical force via Piezo1, resulting in the release of key factors such as IL-1α and TNF-α, which is an important triggering mechanism for the formation of neurotoxic reactive astrocyte.