Abstract
Purpose :
The conserved miR-183/96/182 cluster (miR-183C) is expressed in and regulates the functions of both corneal resident myeloid cells (CRMC) and sensory nerves (CSN) and modulates Pseudomonas aeruginosa (PA) keratitis. This study is to uncover cell type-specific roles of miR-183C in CRMC and CSN and their contribution to corneal functions.
Methods :
Myeloid-specific miR-183C conditional knockout (MS-CKO. LysM-Cre;miR-183Cf/f) and sensory nerve-specific CKO mice [SNS-CKO. Nav1.8-Cre;miR-183Cf/f] and wild-type control (WT) mice were produced. Immunofluorescence and confocal microscopy of flatmount corneas, corneal sensitivity, and tear volume were studied in young adult naïve mice; clinical scoring, quantitative RT-PCR, ELISA, myeloperoxidase (MPO) assay, plate counts after PA infection.
Results :
In naïve mice, similar to the 183C-KO mice, the numbers of CRMC were increased in both MS-CKO and SNS-CKO mice, suggesting that miR-183C in both CMRC and CSN is required for the homeostasis of corneal resident innate immunity.
In the MS-CKO vs WT mice, corneal sensory nerve density, sensitivity to mechanical stimuli and tear volume showed no difference, suggesting miR-183C in myeloid cells has little impact on sensory nerve density and related functions.
In the SNS-CKO mice, densities of both the epithelial/sub basal plexus and stromal nerves in the central cornea were decreased; while in the peripheral region, nerve density in the stromal layer was increased, although it is decreased in the epithelial/sub basal plexus; corneal sensitivity and tear volume were decreased, suggesting miR-183C is required for the development of terminal fine nerves, while large nerves in the stromal layer may be enhanced in the attempt of compensation.
PA infection resulted in increased severity of keratitis in MS-CKO vs WT mice, with increased expression of MMP9 at mRNA level, and MPO activity, but decreased residual bacteria (by plate counts).
Studies on PA keratitis in SNS-CKO mice are ongoing.
Conclusions :
miR-183C has cell type-specific functions in CRMC and CSN, which impose significant but different regulations on the homeostasis and biological functions of cornea and its response to bacterial infection. Corneal sensory innervation plays a major role in tear production. miR-183C modulates tear production through its regulation of corneal sensory innervation, suggesting its potential roles in dry eye disease.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.