Endothelial GATA6 deficiency suppresses intracellular TLR3-interferon signaling in HPAECs and promotes interferon response in HPASMCs

GATA6 is a key transcription factor crucial for maintaining endothelial cell (EC) homeostasis. The dysregulation of endothelial immune function is a central feature in diseases such as pulmonary arterial hypertension (PAH). In this study, we explored the consequences of GATA6 deficiency in human pulmonary arterial endothelial cells (HPAECs) and its impact on immune response pathways. We report that siRNA-induced GATA6 deficiency or the GATA inhibitor led to significant downregulation of interferon response genes and a marked reduction in toll-like receptor 3 (TLR3) expression. GATA6 overexpression enhanced the expression of these genes, and TLR3 inhibition abrogated this response in HPAECs. Furthermore, conditioned medium (CM) from GATA6-deficient HPAECs upregulated interferon genes in pulmonary artery smooth muscle cells (HPASMCs), indicating a paracrine effect. Overall, these findings highlight the critical role of GATA6 in modulating TLR3 signaling and immune responses in endothelial cells and suggest its involvement in endothelial-smooth muscle cell interactions in vascular inflammation. New and NoteworthyWe show that endothelial GATA6 is required for proper activation of intracellular TLR3-interferon signaling in HPAECs. GATA6 loss diminishes interferon pathway responses in endothelial cells while promoting an exaggerated interferon signature in adjacent smooth muscle cells via secreted factors. This work reveals a new GATA6-dependent mechanism governing endothelial-smooth muscle crosstalk in pulmonary vascular disease.