RNA-Seq reveals placental growth factor regulates the human retinal endothelial cell barrier integrity by transforming growth factor (TGF-β) signaling.

Placental growth factor (PlGF or PGF) is a member of the VEGF (vascular endothelial growth factor) family. It plays a pathological role in inflammation, vascular permeability, and pathological angiogenesis. The molecular signaling by which PlGF mediates its effects in non-proliferative diabetic retinopathy (DR) remains elusive. This study aims to characterize the transcriptome changes of human retinal endothelial cells (HRECs) with the presence and the absence of PlGF signaling. Primary HRECs were treated with the PlGF antibody (ab) to block its activity. The total RNA was isolated and subjected to deep sequencing to quantify the transcripts and their changes in both groups. We performed transcriptome-wide analysis, gene ontology, pathway enrichment, and gene-gene network analyses. The results showed that a total of 3760 genes were significantly differentially expressed and were categorized into cell adhesion molecules, cell junction proteins, chaperone, calcium-binding proteins, and membrane traffic proteins. Functional pathway analyses revealed that the TGF-β pathway, pentose phosphate pathway, and cell adhesion pathway play pivotal roles in the blood-retina barrier and antioxidant defense system. Collectively, the data provide new insights into the molecular mechanisms of PlGF's biological functions in HRECs relevant to DR and diabetic macular edema (DME). The newly identified genes and pathways may act as disease markers and target molecules for therapeutic interventions for the patients with DR and DME refractory to the current anti-VEGF therapy.