Patricia Daniele Azevedo Lima

Contrast‐enhanced micro‐computed tomography (micro‐CT) provides high‐resolution, three‐dimensional visualization of small vascular structures in situ, enabling detailed analysis of morphological changes in the perinatal vasculature. The ductus arteriosus (DA) connects the aorta and pulmonary artery (PA), diverting placentally oxygenated blood away from the lungs in utero. Both DA and PA undergo rapid changes in tone with the first breath during the transition from fetal to neonatal oxygen conditions. This study aimed to optimize contrast‐enhanced micro‐CT protocols to enable simultaneous visualization of the DA and pulmonary vasculature during this transition in fetal rabbits. Two contrast agents, an iodine‐based agent (Omnipaque, 300 mg/mL) and two forms of a barium sulphate suspension, were compared to determine which optimally opacified the DA and pulmonary circulation in fetal rabbit kits ( n = 22) from new‐term New Zealand white rabbits ( n = 4). Micro‐CT imaging was performed to assess DA patency and changes in PA caliber across a wide range of vessel diameters from ~50 µm to > 1 mm under hypoxia versus normoxia in anesthetized kits. Omnipaque provided adequate opacification of the DA but limited visualization of the pulmonary vasculature. However, unfiltered 25% barium sulfate in 3% gelatin achieved robust, simultaneous visualization of the DA and pulmonary circulation. This agent optimally enhanced contrast in both large vessels and small PAs, enabling simultaneous assessment of DA constriction and pulmonary arterial vasodilation within 20 min of breathing oxygen. This study established an optimal contrast agent and micro‐CT imaging strategy for post‐mortem assessment of DA and pulmonary vascular morphology during the perinatal transition.

BACKGROUND: DRP1 (dynamin-related protein 1) mediates mitochondrial fission and permits rapid cell cycle progression in hyperproliferative cells by coordinating nuclear and mitochondrial division, a process called mitotic fission. However, DRP1 alone appears insufficient to complete fission, and the link between fission and cell cycle progression is unknown. We hypothesize that DNM2 (dynamin 2) interacts with DRP1 to complete mitochondrial fission and regulate cell cycle progression. We show that DNM2 is upregulated in pulmonary artery smooth muscle cells (PASMCs) in human and rodent pulmonary arterial hypertension (PAH), contributing to disease pathophysiology. METHODS: Mitochondrial morphology, protein colocalization, and fission were assessed using stimulated emission depletion microscopy, protein interactions by immunoprecipitation, and transcriptomics by RNA sequencing. DNM2 was quantified in PASMC and lungs from patients with PAH and rats with pulmonary hypertension (PH), induced by monocrotaline or sugen5416/hypoxia. siDNM2’s effects on cell proliferation, cell cycle progression, and apoptosis were assessed by flow cytometry. Single-cell RNA sequencing was performed on publicly available data sets. siDNM2 was nebulized to monocrotaline- and sugen5416/hypoxia-PH rats, and disease regression was quantified by cardiac catheterization and histology. RESULTS: DNM2 is increased in PAH PASMC. DNM2 interacts with DRP1 via its GTPase domain, permitting mitochondrial translocation and promoting fission. siDNM2 inhibits fission and cell proliferation and increases apoptosis. siDNM2 causes G1/G0 blockade by downregulating RGCC (regulator of cell cycle) with downstream effects on CDK (cyclin-dependent kinase) 4, cyclin D1, and p27 ^kip1 . Conversely, augmenting DNM2 in normal PASMC induces fission and accelerates proliferation. Upregulation of DNM2 in PAH is due to decreased miR-124-3p (microRNA-124-3p) and activation of STAT3 (signal transducer and activator of transcription 3). An miR-124-3p-STAT3-DNM2-DRP1-RGCC pathway accelerates mitotic fission and is upregulated in PASMC, airway epithelium, endothelial cells, fibroblasts, and macrophages in PAH. Nebulized siDNM2 regresses established PH in vivo in rats of both sexes. CONCLUSIONS: DNM2 is a mediator in the terminal steps of DRP1-dependent fission and constitutes a novel therapeutic target in PAH.

Pulmonary arterial hypertension (PAH) is a syndrome characterized by a mean pulmonary artery pressure >20 mmHg and elevated pulmonary vascular resistance >2 Wood Units in the absence of left heart disease, chronic lung disease or hypoxia, and chronic thromboembolic disease. PAH is an obliterative pulmonary arteriopathy that leads to morbidity and mortality, often due to right ventricular failure (RVF). Emerging evidence from preclinical research, using chemical inhibition or genetic depletion of inflammatory mediators, reveals a role for inflammation in the adverse pulmonary vascular remodelling in PAH. More recently, studies have also identified inflammation of the right ventricle (RV) as a potential contributor to RV decompensation and failure. While inflammation contributes to the pathogenesis of PAH, no approved PH-targeted therapies specifically target inflammation. Macrophages are myeloid cells that play a critical role in inflammation and PAH. Their cellular plasticity enables the acquisition of tissue-specific phenotypes and functions that may promote either resolution or exacerbation of inflammatory signalling. Macrophage plasticity in PAH is poorly understood. We examine how alterations in glucose metabolism, particularly the uncoupling of glycolysis from glucose oxidation—a notable feature of PAH observed in various cell populations—impact macrophage polarization and the inflammatory phenotype associated with PAH. The study of immune cell metabolism, known as immunometabolism, is an emerging field that has yet to be explored in PAH. Improving understanding of the inflammatory mechanisms in PAH, particularly novel pathways related to macrophage immunometabolism, may identify new targets for anti-inflammatory therapies for PAH.

Background and Aims: Multiple germline gene variants promote familial and idiopathic pulmonary arterial hypertension (PAH); however, none are consistently identified in associated PAH with connective tissue disease (APAH-CTD). Moreover, the role of somatic variants in genes mediating clonal haematopoiesis of indeterminate potential (CHIP) in PAH is unknown. Here, somatic and germline DNMT3A variants and CHIP gene variants in PAH were evaluated. Methods: Exome sequencing (ES) was compared between PAH Biobank participants (n = 1832 European ancestry/2572 total), vs. gnomAD controls (7509 European ancestry/141 456 total). Subsequently, targeted panel sequencing (TPS) of 22 CHIP genes, including DNMT3A, was performed in PAH (n = 1659) vs. controls (n = 3644). Somatic CHIP variants in the UK Biobank using ES (controls = 448 239; PAH = 2559) were also assessed. DNMT3A mRNA expression was measured in peripheral blood mononuclear cells (PBMCs) of patients with scleroderma APAH-CTD (n = 50), idiopathic PAH (n = 30), scleroderma without PAH (n = 19), and healthy controls (n = 41). Hemodynamic were evaluated in haematopoietic Dnmt3a-knockout mice. Results: Predicted deleterious germline DNMT3A variants were increased in subjects of European ancestry (6/1832) vs. controls (6/7509) (relative risk [RR] = 4.1, P = .018). In the entire PAH Biobank cohort (n = 2572), DNMT3A germline and somatic variants were further enriched (PAH: 1.28% vs. controls: .43%, P = 1.65 × 10−10). Eight DNMT3A mutations (.39%) were likely germline (female/male: 7/1) and 25 (.82%) likely somatic (female/male: 21/4), including 13/33 APAH-CTD participants. TPS identified CHIP in 242 PAH subjects (48% DNMT3A). DNMT3A- and all-CHIP variants were associated with PAH after correcting for age, sex, and age–CHIP interactions (odds ratio [OR]: 25.44, P = 4.50 × 10−5; OR: 23.35, P = 2.87 × 10−8, respectively). In the UK Biobank, CHIP mutations were increased in PAH (PAH = 5.35% vs. Control = 3.45%, P ≤ .0001). DNMT3A was reduced in PAH-PBMCs (area under curve [AUC] = .82) (P < .0001). Haematopoietic Dnmt3a-knockout in mice caused inflammatory PAH, which was attenuated by IL-1β antibody therapy. Conclusions: Germline DNMT3A variants and somatic variants of DNMT3A and CHIP genes increase the risk of PAH, including APAH-CTD, promote inflammation, and constitute potential biomarkers and therapeutic targets.

Summary: Skeletal muscle insulin resistance is a key step in progression of cardiometabolic disease, and impaired mitochondrial bioenergetics has been implicated. However, mitochondrial bioenergetic research in skeletal muscle is limited by the need for muscle biopsies. We sought to determine if platelet bioenergetics could be used as a minimally invasive surrogate for skeletal muscle bioenergetics. Multiple parameters of mitochondrial respiration, measured by high resolution respirometry, correlated between platelets and gastrocnemius muscle in mice. We propose the coupling state of platelet mitochondria reflects that of skeletal muscle in mice, providing a foundation for future research on using platelets as a liquid biopsy for muscle mitochondrial health in cardiometabolic disease, offering early insights into muscle metabolism to enhance clinical biomarker implementation. Graphical

BACKGROUND: Drp1 (dynamin-related protein 1), a large GTPase, mediates the increased mitochondrial fission, which contributes to hyperproliferation of pulmonary artery smooth muscle cells in pulmonary arterial hypertension (PAH). We developed a potent Drp1 GTPase inhibitor, Drpitor1a, but its specificity, pharmacokinetics, and efficacy in PAH are unknown. METHODS: Drpitor1a’s ability to inhibit recombinant and endogenous Drp1 GTPase was assessed. Drpitor1a’s effects on fission were studied in control and PAH human pulmonary artery smooth muscle cells (hPASMC) and blood outgrowth endothelial cells (BOEC). Cell proliferation and apoptosis were studied in hPASMC. Pharmacokinetics and tissue concentrations were measured following intravenous and oral drug administration. Drpitor1a’s efficacy in regressing monocrotaline-PAH was assessed in rats. In a pilot study, Drpitor1a reduced PA remodeling only in females. Subsequently, we compared Drpitor1a to vehicles in control and monocrotaline-PAH females. RESULTS: Drp1 GTPase activity was increased in PAH hPASMC. Drpitor1a inhibited the GTPase activity of recombinant and endogenous Drp1 and reversed the increased fission, seen in PAH hPASMC and PAH BOEC. Drpitor1a inhibited proliferation and induced apoptosis in PAH hPASMC without affecting electron transport chain activity, respiration, fission/fusion mediator expression, or mitochondrial Drp1 translocation. Drpitor1a did not inhibit proliferation or alter mitochondrial dynamics in normal hPASMC. Drpitor1a regressed monocrotaline-PAH without systemic vascular effects or toxicity. CONCLUSIONS: Drpitor1a is a specific Drp1 GTPase inhibitor that reduces mitochondrial fission in PAH hPASMC and PAH BOEC. Drpitor1a reduces proliferation and induces apoptosis in PAH hPASMC and regresses monocrotaline-PAH. Drp1 is a therapeutic target in PAH, and Drpitor1a is a potential therapy with an interesting therapeutic sexual dimorphism.

Annexin A1 (AnxA1) is a glucocorticoid-inducible protein and an important endogenous modulator of inflammation. However, its effect in the endometrial microenvironment is poorly explained. This study aimed to evaluate the role of endogenous AnxA1 in an endometritis mouse model induced by lipopolysaccharide (LPS). Female C57BL/6 wild-type (WT) and AnxA1^−/− mice were divided into two groups: SHAM and LPS. To induce endometritis, mice received a vaginal infusion of 50 μL of LPS (1 mg/mL) dissolved in phosphate-buffered saline. After 24 h, the mice were euthanized, and blood and uteri samples were collected. The endometrium inflammatory scores were significantly increased in the LPS-treated group. AnxA1^−/− mice from the LPS group demonstrated a significant increase in the number of degranulated mast cell levels compared to AnxA1^−/− SHAM mice. The Western blotting analysis revealed that a lack of AnxA1 promoted the upregulation of NLRP3 and pro-IL-1β in the acute endometritis animal model compared to WT LPS animals. LPS-induced endometritis increased the number of blood peripheral leukocytes in both WT and AnxA1^−/− mice compared with SHAM group mice (p < 0.001). AnxA1^−/− mice also showed increased plasma levels of IL-1β (p < 0.01), IL-6, IL-10, IL-17, and TNF-α (p < 0.05) following LPS-induced endometritis. In conclusion, a lack of endogenous AnxA1 exacerbated the inflammatory response in an endometritis model via NLRP3 dysregulation, increased uterine mast cell activation, and plasma pro-inflammatory cytokine release.

Rationale: Dynamin-related protein 1 (Drp1), a large GTPase, mediates mitochondrial fission. Increased Drp1-mediated fission permits accelerated mitosis, contributing to hyperproliferation of pulmonary artery smooth muscle cells (PASMC), which characterizes pulmonary arterial hypertension (PAH). We developed a Drp1 inhibitor, Drpitor1a, and tested its ability to regress PAH. Objectives: Assess Drpitor1a’s efficacy and toxicity in: a)normal and PAH human PASMC (hPASMC); b)normal rats versus rats with established monocrotaline (MCT)-induced PAH. Methods: Drpitor1a’s effects on recombinant and endogenous Drp1-GTPase activity, mitochondrial fission, and cell proliferation were studied in hPASMCs (normal=3; PAH=5). Drpitor1a’s pharmacokinetics and tissue concentrations were measured (n=3 rats/sex). In a pilot study (n=3-4/sex/dose), Drpitor1a (1mg/kg/48-hours, intravenous) reduced adverse PA remodeling only in females. Consequently, we compared Drpitor1a to vehicle in normal (n=6 versus 8) and MCT-PAH (n=9 and 11) females, respectively. Drpitor1a treatment began 17-days post-MCT with echocardiography and cardiac catheterization performed 28-29 days post-MCT. Results: Drpitor1a inhibited recombinant and endogenous Drp1 GTPase activity, which was increased in PAH hPASMC. Drpitor1a inhibited mitochondrial fission and proliferation and induced apoptosis, in PAH hPASMC but not normal hPASMC. Drpitor1a tissue levels were higher in female versus male RVs. In MCT-PAH females, Drpitor1a regressed PA obstruction, lowered pulmonary vascular resistance, and improved RV function, without hematologic, renal, or hepatic toxicity. Conclusions: Drpitor1a inhibits Drp1 GTPase, reduces mitochondrial fission, and inhibits cell proliferation in PAH hPASMC. Drpitor1a caused no toxicity in MCT-PAH and had no significant effect on normal rats or hPASMCs. Drpitor1a is a potential PAH therapeutic which displays an interesting therapeutic sexual dimorphism.

Background: As partial pressure of oxygen (pO ₂ ) rises with the first breath, the ductus arteriosus (DA) constricts, diverting blood flow to the pulmonary circulation. The DA's O ₂ sensor resides within smooth muscle cells. The DA smooth muscle cells’ mitochondrial electron transport chain (ETC) produces reactive oxygen species (ROS) in proportion to oxygen tension, causing vasoconstriction by regulating redox‐sensitive ion channels and enzymes. To identify which ETC complex contributes most to DA O ₂ sensing and determine whether ROS mediate O ₂ sensing independent of metabolism, we used electron leak suppressors, S1QEL (suppressor of site I _Q electron leak) and S3QEL (suppressor of site III _Qo electron leak), which decrease ROS production by inhibiting electron leak from quinone sites I _Q and III _Qo , respectively. Methods and Results: The effects of S1QEL, S3QEL, and ETC inhibitors (rotenone and antimycin A) on DA tone, mitochondrial metabolism, O ₂ ‐induced changes in intracellular calcium, and ROS were studied in rabbit DA rings, and human and rabbit DA smooth muscle cells. S1QEL's effects on DA patency were assessed in rabbit kits, using micro computed tomography. In DA rings, S1QEL, but not S3QEL, reversed O ₂ ‐induced constriction ( P =0.0034) without reducing phenylephrine‐induced constriction. S1QEL did not inhibit mitochondrial metabolism or ETC‐I activity. In human DA smooth muscle cells, S1QEL and rotenone inhibited O ₂ ‐induced increases in intracellular calcium ( P =0.02 and 0.001, respectively), a surrogate for DA constriction. S1QEL inhibited O ₂ ‐induced ROS generation ( P =0.02). In vivo, S1QEL prevented O ₂ ‐induced DA closure ( P 2 ‐induced rises in ROS and DA constriction ex vivo and in vivo. DA O ₂ sensing relies on pO ₂ ‐dependent changes in electron leak at site I _Q in ETC‐I, independent of metabolism. S1QEL offers a therapeutic means to maintain DA patency.

Type 1 von Willebrand disease (VWD) is associated with a reduction in qualitatively normal von Willebrand factor (VWF). Current diagnostic guidelines only take into consideration the contribution of basal VWF levels, despite a lack of correlation with bleeding severity. Defects in stimulated VWF release, which occurs after hemostatic challenge, may contribute to bleeding in type 1 VWD, but the pathogenic mechanisms are poorly defined. In this study, a layered multiomic approach including messenger RNA (mRNA) and microRNA (miRNA) sequencing was used to evaluate transcriptome-wide differences between type 1 VWD- and control-derived endothelial colony forming cells (ECFCs) during basal and stimulated VWF release. ECFCs from 8 patients with type 1 VWD and 4 other patients were included in this study as controls. VWF protein analysis revealed heterogenous responses to stimulation among type 1 VWD and control ECFCs. During basal VWF release, 64 mRNAs and 7 miRNAs were differentially regulated between type 1 VWD and control ECFCs, and 65 putatively pathogenic miRNA-mRNA interactions were identified. During stimulated VWF release, 190 mRNAs and 5 mRNAs were differentially regulated between type 1 VWD and control ECFCs, and 110 putatively pathogenic miRNA-mRNA interactions were identified. Five gene ontology terms including coagulation, regulation of cell shape, and regulation of cell signaling were also differentially regulated in type 1 VWD ECFCs during stimulated release. To our knowledge, we have shown for the first time that transcriptome-wide differences exist between type 1 VWD and control ECFCs. These differences may contribute to bleeding in type 1 VWD, and further investigation may reveal novel biomarkers and therapeutic targets.