Inflamed sensory neurons in dry eye disease secrete substance P, which directly promotes blood vessel growth in the normally vessel-free cornea — and blocking substance P prevents it.
Direct nerve-vessel linkSensory neurons directly promoted vascular cell proliferation and tube formation via substance P
What the researchers found
Sensory neurons from dry eye mice promoted vascular endothelial cell proliferation and tube formation via substance P signaling; blocking SP with spantide I prevented corneal neovascularization.
Why it matters
Corneal neovascularization threatens vision in millions with dry eye disease. Targeting substance P could provide a new approach to prevent abnormal blood vessel invasion of the cornea.
The numbers in context
DED neurons secreted higher SP levels; spantide I significantly reduced corneal neovascularization
How the study worked
Mouse dry eye model (desiccating stress); trigeminal ganglion neuron/VEC co-culture system; SP secretion measurement; spantide I (NK-1 antagonist) treatment in vivo and in vitro; siRNA knockdown of SP.
Who was studied
Mice with induced dry eye disease; trigeminal ganglion neurons and vascular endothelial cells in co-culture
What this study cannot tell us
Mouse model of dry eye; co-culture system is simplified compared to in vivo tissue; substance P may not be the only neuropeptide involved; human validation needed.
How to read the evidence
Moderate — strong mechanistic animal data with co-culture validation and multiple confirmatory approaches (antagonist + siRNA), but no human data.
When this study was published
Published in 2020; substance P's role in ocular inflammation is increasingly recognized.
The bigger picture
This reveals a direct nerve-to-blood-vessel communication pathway driven by substance P. The same mechanism may operate in other tissues where inflammation triggers unwanted blood vessel growth.
Questions still open
- Would NK-1 receptor antagonists (like aprepitant, already FDA-approved for nausea) work as anti-angiogenic eye drops?
- Is substance P-driven neovascularization relevant to corneal transplant rejection?
- Do other neuropeptides (CGRP) also contribute to corneal angiogenesis?
Common questions
Why do blood vessels grow into the cornea during dry eye?
Could eye drops block substance P?
Read the original research
Sensory neurons directly promote angiogenesis in response to inflammation via substance P signaling.
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 34(5), 6229-6243
Citation
Liu, Lingjia; Dana, Reza; Yin, Jia. (2020). Sensory neurons directly promote angiogenesis in response to inflammation via substance P signaling.. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 34(5), 6229-6243. https://doi.org/10.1096/fj.201903236R