The role of melanocytes in the human choroidal microenvironment and inflammation: Insights from the transcriptome

The choroid within the human eye contains a rich milieu of cells including melanocytes. Human choroidal melanocytes (HCMs) absorb light, regulate free radical production, and were recently shown to modulate inflammation. This study aimed to identify key genes and pathways involved in the inflammatory response of HCMs through the use of RNA-seq. Primary HCMs were cultured from donor choroids, RNA was extracted from control and lipopolysaccharide (LPS)-treated HCMs, and mRNA was sequenced. Functional annotation and pathway analysis were performed using gene ontology and gene set enrichment analyses. Representative RNA-seq results were verified with RT-qPCR and protein measurements. We detected 100 differentially expressed genes including an array of CCL and CXCL cytokines and mediators of cell-cell and cell-matrix adhesion, such as ICAM1, CLDN1, CCN3, ITGA1 and ITGA11. Functional annotation showed that these gene sets control inflammatory pathways, immune cell trafficking, cell-cell adhesion, interactions with the extracellular matrix and blood vessels, angiogenesis and epithelial-to-mesenchymal transitions. Our study provides insights into the transcriptional regulation of primary HCMs in response to inflammatory stimuli and identifies novel melanocyte-driven mechanisms potentially involved in choroidal homeostasis and inflammation.