Abstract An unremitting increase in lung vascular permeability is the pathophysiological hallmark of acute lung injury (ALI) and drives both severity and mortality. Therapies with the capacity to quickly restore vascular integrity in ALI remains a serious unmet need. Our laboratory was first to report both the vascular barrier-protective effects of sphingosine-1-phosphate (S1P) and S1P analogues, such as tysiponate (TySIP), and the efficacy of peptide inhibitors (PIK) of non-muscle myosin light chain kinase (nmMLCK) as dual complementary strategies to reduce vascular permeability. The current study evaluates a novel nanocarrier (NTyP-100) containing conjugated TySIP and encargoed PIK as a pharmacologic approach to vascular barrier restoration in rodent models of LPS-induced ALI. NTyP-100 (or control) was delivered intravenously to wild-type C57BL/6J mice exposed to a “one-hit” lipopolysaccharide (LPS; 18 hours) ALI model or to Sprague–Dawley rats challenged by a “2-hit” ALI model combining LPS (18 hours) and exposure to high tidal volume mechanical ventilation (4 hours). Compared to TySIP or PIK alone, intravenous NTyP-100 produced the highest reduction (∼40%) in inflammatory injury in murine and rat ALI models (hematoxylin and eosin, immunohistochemistry p-MLC staining, BAL cells), with marked reductions in vascular leak (Evan Blue Dye leakage, BAL protein) and biochemical indices of inflammation. Genomic studies underscored NTyP-100 attenuation of ALI-mediated dysregulated barrier-regulatory signaling pathways (inflammatory response, innate immunity, TNF, IL-17, apoptosis). These studies demonstrate the successful therapeutic targeting of vascular barrier properties and supports the NTyP-100 nanocarrier as a strategy to address the unmet need for novel therapeutics that mitigate inflammatory injury and vascular permeability.
Abstract Right ventricular (RV) failure is the major cause of mortality in pulmonary hypertension (PH). Adaptive angiogenesis and RV endothelial cell (RVEC) function are major modifiers of RV adaptation in PH, but the underlying mechanisms and their regulators remain incompletely understood. RV adaptation in PH is sexually dimorphic, and 17β-estradiol (E2) exerts protective effects on RV cardiomyocytes. Whether E2 modifies angiogenesis and RVEC function in RV failure remains unknown. We hypothesized that E2 and estrogen receptor α (ERα) promote RV angiogenesis and RVEC homeostasis in PH and aimed to identify underlying mechanisms. We assessed E2’s angiogenic effects using cultured human cardiac microvascular endothelial cells (hCMVECs), RVECs from PH patients with RV failure, and RVECs from sugen/hypoxia (SuHx) and monocrotaline rat models. In vivo, we evaluated RV capillary density in PH rats treated with E2 or ERα-selective agonist. Apelin signaling was evaluated via apelin receptor (APLNR) blockade and knockdown studies. E2 preserved angiogenesis in male hCMVECs and RV capillary density in male and female SuHx-PH rats. E2 reversed angiogenic alterations in RVECs from SuHx-PH rats via APLNR signaling. In RVECs from RV failure patients, E2 stimulated vascular network formation. In rat and human PH-RVECs, ERα was necessary and sufficient to mediate E2-induced angiogenesis. Activation of ERα with ERα-specific agonist restored RV capillary density in vivo. ERα-mediated angiogenesis required apelin signaling. These data indicate that E2 promotes RV angiogenesis via ERα and apelin signaling and identify a novel ERα–apelin axis in RVECs as a potential therapeutic target to restore RV vascular integrity in PH.
