Abstract 17047: Contribution of MDA-5/IL-10RA to Pulmonary Artery Homeostasis and Pulmonary Arterial Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a progressive and lethal disease. The current treatment options do not target pulmonary artery endothelial cell (PAEC) dysfunction. We have previously shown a role for the endosomal double stranded (ds) RNA receptor toll-like receptor 3 (TLR3) and its regulation via interleukin-10 (IL-10) in promoting PAEC dysfunction and experimental pulmonary hypertension (PH). Yet the role of the cytosolic dsRNA receptor melanoma differentiation factor 5 (MDA-5) in endothelial dysfunction is not known.

Hypothesis: We hypothesized that a deficient MDA-5/IL-10 receptor A (IL-10RA) signaling axis expression exists in PAH PAECs as a potential cause of endothelial dysfunction. Goals: Our goal is to test the role of a potential new axis of MDA-5 and IL10RA in EC homeostasis and pulmonary hypertension.

Methods: Western blot analysis of control and PAH PAECs and PA smooth muscle cells (SMCs) was conducted. Gene silencing was done using siRNA targeting MDA-5 and IL-10RA, followed by bulk RNA sequencing. Apoptosis was tested using Annexin V binding. IL-10 whole body knockout (IL-10 ^-/- ) and endothelial-specific IL-10RA haploinsufficient mice (IL-10RA ^fl/wt Cdh5-Cre ⁺ ) and appropriate controls were exposed to chronic hypoxia and SU5416 (Hx/Su), followed by hemodynamics.

Results: Our data show a reduction of MDA-5 in PAECs, but not in PASMCs. PAH PAECs further had reduced IL-10RA expression and application of dsRNA elevated IL-10RA expression in PAH PAECs. Knockdown of MDA-5 and IL-10RA caused differential expression of 2533 and 2638 genes, respectively. Comparative analysis revealed an overlap of differentially expressed genes (DEGs) in canonical pathways including reduced nitric oxide, VEGF, Apelin and Integrin signaling. Comparison also yielded overlapping DEGs for reduced cell survival, impaired cytoskeleton organization and migration. Gene silencing of MDA-5 resulted in increased PAEC apoptosis. IL-10 ^-/- and IL-10RA ^fl/wt Cdh5-Cre ⁺ mice showed exaggerated PH.

Conclusions: Our data indicate an impaired cytosolic dsRNA receptor MDA-5 and IL-10RA axis in PAH PAECs which contributes to endothelial dysfunction and PH. Experiments are underway to identify the detailed mechanisms underlying our findings.