Abstract
Purpose :
Substance P (SP) is a neuropeptide, expressed by an array of cells, and found to be an active mediator of inflammation. Recently, the role of SP blockade was described to ameliorate the severity of acute dry eye disease (DED) by preserving regulatory T cells (Tregs) function, inhibiting antigen-presenting cells (APCs) maturation, and suppressing T effector cells. This study aimed to investigate the effect of SP on memory T cells and the potential strategy of blocking SP in chronic DED.
Methods :
To induce chronic DED, after 14 days of low humidity animals were placed in a normal environment for additional 14 days.
Corneal fluorescein staining (CFS) scores were assessed using the NEI scale. Cervical draining lymph nodes (DLNs) were harvested from naïve and DED mice. To isolate mTh17 cells and eTh17 cells, we used a combination of magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting (FACS). Cells were incubated separately with either 1 mg/ml SP, or a combination of SP and NK1R antagonist (1 mg/ml). The phenotypic and functional changes in memory Th17 cells (mTh17) were detected by flow cytometry.
Results :
SP level increased from d14 to d21 and maintained its high level at d28. In vitro cultures of effector T cells in the presence of SP led to a significant generation of CD44hi Th17 cells, and the increase was reversed by NK1R antagonist. Those CD44hi Th17 cells showed high expression of IL-7R and IL-15R. In vivo experiments showed that treatment with topical NK1R antagonist resulted in a significant reduction of dry eye disease severity assessed by the corneal epithelial disease score.
Conclusions :
In summary, our study demonstrates that SP plays a key role in mTh17 cells generation and maintenance. Topical application of NK1R antagonist can effectively alleviate autoimmune DED symptom severity. Further studies are warranted to evaluate the adverse effects of long-term use of NK1R antagonists on chronic dry eye. This study provide a translation potential of SP blockade in alleviating the symptoms of chronic DED.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.