The miR-183/96/182 Cluster Regulates Sensory Innervation, Resident Myeloid Cells and Functions of the Cornea Through Cell type-specific Target Genes

Abstract

Purpose : The conserved miR-183/96/182 cluster (miR-183C) is expressed in both corneal resident myeloid cells (CRMCs) and sensory nerves (CSN) and modulates corneal immune/inflammatory responses. This study’s purpose is to uncover the cell type-specific roles of miR-183C in CRMC and CSN and how they contribute to corneal physiology.

Methods : Myeloid-specific miR-183C conditional knockout (MS-CKO), sensory nerve-specific CKO (SNS-CKO) and the conventional miR-183C KO and their corresponding wild-type control (WT) mice were produced. Immunofluorescence, confocal microscopy of flatmount corneas, corneal sensitivity, and tear volume assays were performed in young adult naïve mice; 3’RNA sequencing (Seq) in the trigeminal ganglion (TG), cornea and FACS-purified CRMCs.

Results : Similar to conventional KO mice, the numbers of CRMCs were increased in both MS-CKO and SNS-CKO vs age- and sex-matched WT control littermates, suggesting intrinsic and extrinsic regulations of miR-183C on CRMCs. In the miR-183C KO and SNS-CKO, but not the MS-CKO mice, CSN density was decreased in the epithelial layer of the cornea, but not the stromal layer. Functionally, corneal sensitivity and basal tear volume were reduced in the KO and SNS-CKO, but not in the MS-CKO mice. Tear volume in males was consistently higher than female WT mice. Bioinformatic analyses of RNA seq data revealed a series of cell-type specific target genes of miR-183C in TG sensory neurons and CRMCs. Targets in the TG and corneal sensory nerves were enriched with genes involved in axonal guidance, neuronal projection and synaptic functions, while CRMC-specific target genes in a range of immune/infection related pathways. Intriguingly, TG neuron-specific targets were also enriched in chemokine signaling, and pathways regulating other corneal cell types, e.g. epithelial, endothelial cell and fibroblast migration; while CRMC-specific targets in neuronal synaptic functions and cell-cell interaction and migration pathway.

Conclusions : miR-183C imposes intrinsic and extrinsic regulation on the establishment and function of CSN and CRMCs as well as neuro-immune-epithelial-stromal-endothelial interactions through cell type-specific target genes. miR-183C modulates tear production through its regulation of corneal sensory innervation, suggesting a potential role in dry eye disease.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.