Trigeminal nerve-derived substance P regulates limbal stem cells by the PI3K-AKT pathway.

Trigeminal nerve-derived substance P (SP), a widespread neuropeptide, is known to maintain the corneal epithelial homeostasis and promote the closure of wound healing. Using comprehensive and assays and RNA-sequencing analysis, we aimed to unveil the positive effects of SP on the biological characteristics of limbal stem cells (LSCs) and the underlying mechanism. SP enhanced the proliferation and stemness of LSCs Correspondingly, it rescued corneal defects, corneal sensitivity, and the expression of LSC-positive markers in a neurotrophic keratopathy (NK) mouse model . Topical injection of a neurokinin-1 receptor (NK1R) antagonist caused similar pathological changes as in corneal denervated mice and attenuated LSC-positive markers levels. Mechanistically, we revealed that SP regulated LSCs functions by modulating the PI3K-AKT pathway. Our findings showed that the trigeminal nerve regulates LSCs by releasing SP, which may provide new insights into the regulation of LSCs' fate and stem cell therapy.