324 The role of CCN3 in lung endothelial identity and function

Abstract

OBJECTIVES/GOALS: Idiopathic Pulmonary Fibrosis (IPF) is a fatal disease of lung scarring. Aberrant vascular remodeling is a contributor to IPF progression. We have identified CCN3 as an endothelial gene that is upregulated in resolving but not in persistent lung fibrosis in mice. Here we tested the role of CCN3 in lung microvascular endothelial function. METHODS/STUDY POPULATION: RNAi loss of function experiments were used to evaluate the role of CCN3 in lung endothelial biology. Human lung microvascular endothelial cells (HLMECs) were transfected with human CCN3 siRNA and analyzed via qPCR to assess expression of endothelial transcripts, via wound healing assay for assessment of migratory function, and via 2D tube formation assay for assessment of angiogenic function. To ascertain the effect of HLMECs on Normal Human Lung Fibroblasts (NHLFs), conditioned media (CM) from endothelial cells with control and CCN3 siRNA was applied to TGFβ primed fibroblasts and qPCR was used to measure expression levels of pro-fibrotic transcripts. Recombinant human CCN3 protein was subsequently used to confirm the gain of function role of CCN3 in lung endothelial biology using a subset of these assays. RESULTS/ANTICIPATED RESULTS: CCN3 is a secreted matricellular protein thought to be involved in angiogenesis, cell adhesion, cell migration, and inflammatory responses in endothelial cells. In other organs, CCN3 suppresses expression of fellow matricellular protein, CCN2 (CTGF); importantly, CCN2 is a known pro-fibrotic mediator of aberrant tissue remodeling in the fibrotic lung. Upon CCN3 knockdown in HLMECs, we observed reduced transcripts for inflammatory and pro-fibrotic genes, along with impaired endothelial function in wound healing and angiogenesis assays. CM from CCN3 knockdown endothelial cells enhanced the pro-fibrotic effects of TGFβ in NHLFs. Addition of recombinant CCN3 to HLMECs generated, conditioned media that reduced fibroblast pro-fibrotic activation. DISCUSSION/SIGNIFICANCE: We have shown that matricellular protein- CCN3 plays a fundamental role in endothelial identity and function and could be a promising therapeutic target in IPF. A future goal is to restore levels of genes such as CCN3 in the aged vasculature in the setting of lung fibrosis to test their capacity to promote vascular repair and fibrosis resolution.