Abstract
Pathological neovascularization in choroid, a leading cause of blindness, is a characteristic of many fundus diseases, such as diabetic retinopathy and age-related macular degeneration. The present study aimed to elucidate the key signaling pathways in choroidal neovascularization (CNV) by analyzing the mRNA profiles of choroid and retina in tree shrews with CNV. We induced choroidal angiogenesis by laser photocoagulation in 15 tree shrews and obtained mRNA profiles of their choroids and retinas by high-throughput transcriptome sequencing. Hierarchical cluster analysis, weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) network analysis, hematoxylin and eosin (HE) staining, CD31 immunohistochemistry (IHC), and reverse transcription quantitative PCR (RT-qPCR) were performed. After laser photocoagulation, we obtained a total of 350 differentially expressed genes (DEGs) in the choroid, including 59 genes in Module-FASN (“ME-FASN”) module and 28 genes in Module-RPL (“ME-RPL”) module. A total of 69 DEGs in retina, including 20 genes in Module-SLC (“ME-SLC”) module. Bioinformatics analysis demonstrated that DEGs in choroid were mainly involved in membrane transport; DEGs in “ME-RPL” were prominent in pathways associated with IgA production, antigen presentation, and cell adhesion molecules (CAMs) signaling. DEGs in “ME-FASN” were involved in fatty acid metabolism and PPAR signaling pathway, while DEGs in “ME-SLC” were involved in GABAergic synapse, neuroactive life receptor interaction, cholinergic synapse, and retrograde endocannabinoid signaling pathway. PPI network analysis demonstrated that the ribosomal protein family genes (RPL31, RPL7, RPL26L1, and RPL19) are key factors of “ME-RPL,” acyl-CoA superfamily genes (ACACA, ACAT1, ACAA2, and ACACB) and FASN are key factors of “ME-FASN” and superfamily of solid carrier genes (SLC17A6, SLC32A1, SLC12A5, and SLC6A1) and complement genes (C4A, C3, and C2) are key factors of “ME-SLC.” In conclusion, the present study discovered the important signal transductions (fatty acid metabolic pathway and CAMs signaling) and genes (ribosomal protein family and the complement system) in tree shrew CNV. We consider that our findings hold implications in unraveling molecular mechanisms that underlie occurrence and development of CNV.
Highlights
Choroidal neovascularization (CNV) is the formation of new blood vessels in the choroid
Inflammatory cells and cytokines are involved in its pathogenesis, while tumor necrosis factor-α (TNF-α), interleukins 6 (IL6), and intercellular cell adhesion molecules 1 (ICAM-1) released by macrophages and neutrophils promote the occurrence and development of CNV (Jin et al, 2010)
Pathogenesis of CNV is influenced by the choroid microenvironment that is composed of extracellular matrix, cytokines, platelet-derived growth factor (PDGF), fibroblast growth factors, tumor necrosis factor-α (TNF-α), pigment epithelium-derived growth factor, interleukins, the complement system, ephrins, and angiopoietins (Lambert et al, 2016)
Summary
Choroidal neovascularization (CNV) is the formation of new blood vessels in the choroid. The blood vessels form/develop between the retinal pigment epithelium (RPE) and Bruch’s membrane. They extend through the retinal neuroepithelial layer eventually forming a fibrous vascular tissue. The pathogenesis of CNV remains poorly understood, it is believed to involve a variety of cell growth factors, such as the vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF), available in the local microenvironment (Ming et al, 2011). Inflammatory cells and cytokines are involved in its pathogenesis, while tumor necrosis factor-α (TNF-α), interleukins 6 (IL6), and intercellular cell adhesion molecules 1 (ICAM-1) released by macrophages and neutrophils promote the occurrence and development of CNV (Jin et al, 2010)
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