Molecular analysis of the blood-nerve barrier in health and diabetes

PROJECT SUMMARY In most organs, the vasculature is permeable to many blood-borne molecules and cells, but the vessels of the nervous system tightly regulate the movement of ions, molecules and cells between the blood and the nervous tissue. In this way, the vasculature of the nervous system rigorously controls the neural environment to

allow for proper neuronal function, and protect the neural tissue from toxins and pathogens. The blood nerve barrier (BNB) is the set of vascular characteristics that describes this strict regulation in the peripheral nervous system (PNS) and is analogous in function to the blood brain barrier (BBB) in the central nervous system (CNS).

Dysfunction of either of these barrier properties has been associated with various pathologies including diabetic peripheral neuropathy in the PNS and multiple sclerosis in the CNS. Researchers have made great strides in answering many fundamental questions about BBB biology, especially by leveraging the use of RNA sequencing

to identify genes of importance. In contrast, little is known about the cellular and molecular mechanisms responsible for BNB function in health and dysfunction in disease. Although the differences in cell types between the CNS and PNS are well known, no one has performed an in-depth molecular comparison of the BBB and

BNB. Given the clinical relevance of BBB and BNB dysfunction in disease, a thorough comparison of both would be valuable to advance novel therapeutics for both PNS and CNS diseases, alike. As such, the principal goal of this proposal is to leverage the use of single cell RNA sequencing technology to compare the gene

expression of the key cell types that form the BNB and BNB under physiological conditions, and characterize changes in the gene expression of the BNB during diabetic peripheral neuropathy. To accomplish this, we will first perform single cell RNA sequencing comparing adult mouse sciatic and optic nerves

since these are analogous regions from the PNS and CNS and will have BNB and BBB vasculature, respectively. We will then perform single cell RNA sequencing on sciatic nerves from diabetic mice at early, mid, and late- stages of the disease, comparing them with healthy controls. Overall, this proposal will provide transcriptomic

information on the differences between the BNB and BBB in health and BNB dysfunction in a diabetic model, providing a framework for a more complete understanding of the BNB in an aim to develop novel therapeutic strategies.