Leary, P. J. | Search bioRxiv

bioRxiv2025

Liver angiocrine myeloid-derived growth factor protects against endothelial dysfunction in pulmonary arterial hypertension

Myeloid-derived growth factor (MYDGF) is a hepatic angiokine with protective effects in systemic vascular beds, but its role in pulmonary arterial hypertension (PAH) is unknown. We hypothesized that hepatic MYDGF deficiency contributes to pulmonary endothelial activation in PAH and that recombinant MYDGF could rescue endothelial injury. In the Sugen-hypoxia (SuHx) rat model, hepatic MYDGF expression was decreased, while pulmonary vascular cell adhesion molecule-1 (VCAM-1) expression was increased. Human hepatic sinusoidal endothelial cells exposed to pro-inflammatory macrophage conditioned media downregulated MYDGF, and recombinant MYDGF restored pulmonary artery endothelial cell resistance to inflammatory activation via MAP4K4-NF{kappa}B signaling. In the Brown University PHiNE PAH cohort (n=41 PAH, n=27 controls), plasma proteomics demonstrated increased MYDGF in PAH patients compared with controls, but MYDGF levels declined with worsening liver stiffness and correlated with higher pulmonary vascular resistance. In the independent Servetus PAH cohort (n=117), higher plasma MYDGF was associated with mortality and right ventricular dilation. Together, these findings demonstrate hepatic MYDGF deficiency in experimental PAH, tissue specificity of endothelial MYDGF to the liver, and MYDGFs potential to mitigate pulmonary endothelial inflammation. However, human data suggest a paradoxical association of elevated circulating MYDGF with adverse outcomes, underscoring the complex biology of angiogenic growth factors in PAH. MYDGF may represent a novel hepatic angiokine linking systemic inflammation, liver dysfunction, and pulmonary vascular disease.

molecular biology↗

bioRxiv2025

Pressure Points: Endothelial Responses to Shear Stress and Pressure in Health and Pulmonary Arterial Hypertension

BackgroundHemodynamic forces exert a profound influence on endothelial signaling and, when abnormal, contribute centrally to human vascular disease. Pulmonary arterial hypertension (PAH) is characterized by both hemodynamic derangement and pulmonary arterial endothelial cell (PAEC) dysfunction. Despite importance in disease initiation and progression, the combined effects of shear and pressure forces on PAEC biology remain incompletely understood, particularly in the context of PAH. MethodsPAECs obtained at explant from controls and patients with idiopathic PAH or congenital heart disease-associated PAH (CHD-PAH) were cultured in a custom resistor-coupled microfluidic platform and exposed to static, low (3 dyne/cm{superscript 2}), or high (20 dyne/cm{superscript 2}) shear stress under either low or elevated (60 mmHg) pressure. After 24 hours, we assessed cellular morphology and performed transcriptomic analysis via bulk RNA sequencing, incorporating analyses of PAH subtype and donor sex. ResultsMorphologically, PAECs (n=18 donors) aligned with flow under high, but not low, shear, and alignment was not significantly altered by disease state or pressure. As expected, shear stress fundamentally reorganized the PAEC transcriptome. The "dose-response" to increasing shear differed across biological pathways in six statistically significant patterns. Increasing shear led to divergence in transcription between control and PAH cells, particularly in pathways involved in immune activation, stress signaling, and vascular remodeling, with subtype differences also observed. Pressure had modest effects on transcription, with CHD-PAH PAECs notably displaying pressure-induced stress and inflammatory signaling. We identified sexual dimorphism in the endothelial shear response, including that male cells under shear enriched for proliferative and angiogenic pathways and female cells for fatty acid metabolism and stress responses. ConclusionsWe provide a systems-level overview of how shear and pressure shape PAEC transcription, revealing divergent responses across disease state, PAH subtype, and donor sex. These findings highlight the need for further investigation into mechanosensitive pathways in PAH as potential novel therapeutic targets.

bioengineering↗