Claire Hung
BME PhD Proposal Presentation

Date: 2025-10-31
Time: 10:00 am - 12:00 pm
Location / Meeting Link: HSRBII N600 / https://emory.zoom.us/j/94858031964

Committee Members:
Alyssa Panitch; Hanjoong Jo; W. Robert Taylor; David Myers; Haian Fu


Title: Role of cytokines in endothelial reprogramming under disturbed flow and hypercholesterolemia during atherogenesis

Abstract:
Atherosclerotic disease is the leading cause of death worldwide. Atherosclerotic plaques preferentially develop in arterial regions exposed to disturbed flow (d-flow), whereas regions under unidirectional, stable flow (s-flow) are protected. Our previous single-cell RNA sequencing (scRNA-seq) study using the mouse partial carotid ligation (PCL) model, validated by lineage tracing and human plaque analysis, revealed that under d-flow and hypercholesterolemia, endothelial cells (ECs) undergo Flow-Induced Reprogramming of Endothelial cells (FIRE), characterized by EC inflammation, endothelial-to-mesenchymal transition (EndMT), and two newly identified transitions: endothelial-to-immune-like (EndIT) and endothelial-to-foam cell (EndFT) transitions. However, the mechanisms and therapeutic significance of EndIT and EndFT in atherosclerosis remain unknown. To address this critical knowledge gap, we developed an in vitro shear model that recapitulates both protective (s-flow) and pro-atherogenic (d-flow + hypercholesterolemia) environments. Although d-flow and cholesterol alone did not induce robust EndIT or EndFT in EC culture, our scRNA-seq data revealed that five proinflammatory cytokines – TNFα, IL-1β, IFNγ, TGF-β1, and TGF-β2 – are highly expressed in neighboring immune and stromal cells under d-flow and hypercholesterolemia. Consistent with findings from the CANTOS trial, which showed reduced cardiovascular events clinically through IL-1β inhibition, these results suggest that cytokine signaling plays a key role in FIRE and atherogenesis. We therefore hypothesize that proinflammatory cytokines, in combination with d-flow and hypercholesterolemia, are required to induce full FIRE in vitro, and that endothelial-specific inhibition of cytokine signaling will suppress EndIT, EndFT, and atherosclerosis progression. To test this hypothesis, in Aim 1, we will develop an in vitro platform to induce FIRE in human aortic ECs and define optimal conditions of flow, cholesterol, and cytokine stimulation. In Aim 2, we will define the individual and combined roles of the five cytokines in driving EndIT and EndFT. We will test various cytokine combinations and perform receptor inhibition and knockdown studies to identify the key cytokine(s) driving EndIT and EndFT. In Aim 3, we will evaluate how endothelial-specific inhibition of cytokine signaling affects EndIT, EndFT, and plaque development using the mouse PCL model. Nanoparticles targeting ECs at d-flow sites will be developed to enable targeted delivery of drugs inhibiting cytokine downstream signaling pathways. Together, these studies will provide novel mechanistic insight into EndIT and EndFT and uncover new endothelial-targeted therapeutic strategies for atherosclerosis.