Abstract Endothelial‐to‐mesenchymal transition (EndoMT) plays an important role in pulmonary hypertension (PH) but the molecular mechanisms regulating EndoMT remain to be defined. We demonstrate that the axis of the transcription factors PPARγ (Peroxisome Proliferator‐Activated Receptor gamma) and ETV2 (ETS variant 2) play important roles in the pathogenesis of PH. Decreased levels of the expression of PPARγ and ETV2 along with reduced endothelial and increased EndoMT markers are consistently observed in lungs and pulmonary artery endothelial cells (PAECs) of idiopathic pulmonary arterial hypertension patients, in hypoxia‐exposed mouse lungs, human PAECs, and in induced‐EndoMT cells. Etv2+/− mice spontaneously developed PH and right ventricular hypertrophy (RVH), associated with increased EndoMT markers and decreased EC markers. Interestingly, chronic hypoxia exacerbated right ventricular systolic pressure and RVH in Etv2+/− mice. PPARγ transcriptionally activates the ETV2 promoter. Consistently, while mice overexpressing endothelial PPARγ increases the expression of ETV2 and endothelial markers with reduced EndoMT markers, endothelial PPARγ KO mice show decreased ETV2 expression and enhanced EndoMT markers. Inducible overexpression of ETV2 under induced‐EndoMT cell model reduces number of cells with mesenchymal morphology and decreases expression of mesenchymal markers with increased EC makers, compared to control. Therefore, our study suggests that PPARγ‐ETV2 signaling regulates PH pathogenesis through EndoMT.

"LKB1 Regulates PH Endothelial Cell Mitochondria: Another Layer of the Pulmonary Vascular Onion?." American Journal of Respiratory Cell and Molecular Biology, 0(ja), pp.

Abstract Evaluation for right ventricular (RV) dysfunction is an important part of risk assessment in care of patients with pulmonary hypertension (PH) as it is associated with morbidity and mortality. Echocardiography provides a widely available and acceptable method to assess RV function. RV global longitudinal strain (RVGLS), a measure of longitudinal shortening of RV deep muscle fibers obtained by two‐dimensional echocardiography, was previously shown to predict short‐term mortality in patients with PH. The purpose of the current study was to assess the performance of RVGLS in predicting 1‐year outcomes in PH. We retrospectively identified 83 subjects with precapillary PH and then enrolled 50 consecutive prevalent pulmonary arterial hypertension (PAH) subjects into a prospective validation cohort. Death as well as combined morbidity and mortality events at 1 year were assessed as outcomes. In the retrospective cohort, 84% of patients had PAH and the overall 1‐year mortality rate was 16%. Less negative RVGLS was marginally better than tricuspid annular plane systolic excursion (TAPSE) as a predictor for death. However, in the prospective cohort, 1‐year mortality was only 2%, and RVGLS was not predictive of death or a combined morbidity and mortality outcome. This study supports that RV strain and TAPSE have similar 1‐year outcome predictions but highlights that low TAPSE or less negative RV strain measures are often false‐positive in a cohort with low baseline mortality risk. While RV failure is considered the final common pathway for disease progression in PAH, echocardiographic measures of RV function may be less informative of risk in serial follow‐up of treated PAH patients.

The Department of Veterans Affairs (VA) initiative to enhance recruitment of diverse biomedical scientists from Historically Black Colleges and Universities (HBCUs) through the VA Career Development Program has provided a unique opportunity for HBCUs to partner with VA to strengthen diversity recruitment efforts. The Atlanta VA Health Care System and the Morehouse School of Medicine (MSM) enjoy a productive and growing interinstitutional collaboration. The partnership between the Atlanta VA and MSM provides the unique opportunity for MSM to increase research opportunities for faculty and students while providing a pipeline of diverse candidates for the Atlanta VA to enhance recruitment of diverse HCBU biomedical scientists. This relationship led to the creation of an inaugural HBCU Core Recruitment Site (CRS) at MSM and the Atlanta VA. The CRS provides a pathway to identify and recruit young diverse investigators who are eligible to compete for VA Career Development Award funding. This Atlanta VA/MSM CRS initiative established a pipeline program to further enhance diversity in the VA scientific workforce. In this review, the Atlanta VA/MSM CRS is presented as a potential model for maximizing the VA initiative to enhance the recruitment of diverse candidates from HBCUs.

BACKGROUND:Chronic alcohol ingestion predisposes to lung injury and disrepair during sepsis. Our previous studies outlined roles for transforming growth factor-beta 1 (TGFβ1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in epithelial barrier homeostasis and how alcohol perturbs their expression and signaling. Here we hypothesize that ethanol-exposed lung fibroblasts (LF) are a source of dysregulated TGFβ1 and GM-CSF and thereby alter airway epithelial barrier function.METHODS:Human or rat LF were cultured ± ethanol for 2 weeks and then co-cultured with human or rat airway epithelial cells (AEC) seeded on Transwell permeable supports. In selected groups, a TGFβ1 receptor type 1 (TGFβR1) inhibitor (SB431542) or a TGFβ1 neutralizing antibody was applied. Transepithelial electrical resistance (TER) was measured prior to co-culture and on day 5 of co-culture. AEC were then analyzed for the expression of selected tight junction and mesenchymal proteins, and transwell membranes were analyzed by immunofluorescence microscopy for ZO-1 expression and localization. TGFβ1 and GM-CSF levels in conditioned media from the co-cultures were quantified by ELISA.RESULTS:AEC co-cultured with ethanol-exposed LF (ELF) showed a significant reduction in TER and corresponding decreases in ZO-1 expression, whereas collagen type 1A1 and α-smooth muscle actin protein expression were increased. In parallel, in conditioned media from the ELF + AEC co-cultures, activated TGFβ1 levels increased and GM-CSF levels decreased. Notably, all the effects of ELF on the AEC were prevented by blocking TGFβ1 activity.CONCLUSIONS:Prior ethanol exposure to LF induces barrier dysfunction in naive AEC in a paracrine fashion through activation of TGFβ1 signaling and suppression of GM-CSF. These experimental findings provide a potential mechanism by which chronic alcohol ingestion impairs airway epithelial integrity and renders individuals susceptible to lung injury.

Enteric neuron degeneration has been observed during aging, and in individuals with metabolic dysfunction including obesity and diabetes. Honokiol, a naturally occurring compound, is an activator of Sirtuin-3 (SIRT3) that has antioxidant activity. Its role in modulating enteric neuron-specific neurodegeneration is unknown. We studied the effects of honokiol and its fluorinated analog, hexafluoro-honokiol, on enteric neuronal differentiation and survival. We used a previously established model of mouse primary enteric neuronal cells and an enteric neuronal cell line treated with palmitate (PA) and lipopolysaccharide (LPS) to induce mitochondrial dysfunction and enteric neuronal cell death. The effect of honokiol and hexafluoro-honokiol was assessed on neuronal phenotype, fiber density, differentiation, and pyroptosis. Honokiol and hexafluoro-honokiol significantly increased neuronal networks and fiber density in enteric neurons and increased levels of neuronal nitric oxide synthase and Choline acetyltransferase mRNA. Hexafluoro-honokiol and honokiol also significantly increased SIRT3 mRNA levels and suppressed palmitate and LPS-induced neuronal pyroptosis. SIRT3 knock-down prevented the hexafluoro-honokiol mediated suppression of mitochondrial superoxide release. Our data supports a neuroprotective effect of honokiol and its derivative and these could be used as prophylactic or therapeutic agents for treating enteric neurodegeneration and associated motility disorders.

The innate immune response to P. aeruginosa pulmonary infections relies on a network of pattern recognition receptors, including intracellular inflammasome complexes, which can recognize both pathogen- and host-derived signals and subsequently promote downstream inflammatory signaling. Current evidence suggests that the inflammasome does not contribute to bacterial clearance and, in fact, that dysregulated inflammasome activation is harmful in acute and chronic P. aeruginosa lung infection. Given the role of mitochondrial damage signals in recruiting inflammasome signaling, we investigated whether mitochondrial-targeted therapies could attenuate inflammasome signaling in response to P. aeruginosa and decrease pathogenicity of infection. In particular, we investigated the small molecule, ZLN005, which transcriptionally activates peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis, antioxidant defense, and cellular respiration. We demonstrate that P. aeruginosa infection promotes the expression of inflammasome components and attenuates several components of mitochondrial repair pathways in vitro in lung epithelial cells and in vivo in an acute pneumonia model. ZLN005 activates PGC-1α and its downstream effector, Sirtuin 3 (SIRT3), a mitochondrial-localized deacetylase important for cellular metabolic processes and for reactive oxygen species homeostasis. ZLN005 also attenuates inflammasome signaling induced by P. aeruginosa in bronchial epithelial cells and this action is dependent on ZLN005 activation of SIRT3. ZLN005 treatment reduces epithelial-barrier dysfunction caused by P. aeruginosa and decreases pathogenicity in an in vivo pneumonia model. Therapies that activate the PGC-1α-SIRT3 axis may provide a complementary approach in the treatment of P. aeruginosa infection.

Pulmonary hypertension (PH) comprises a diverse group of disorders that share a common pathway of pulmonary vascular remodeling leading to right ventricular failure. Development of anti-remodeling strategies is an emerging frontier in PH therapeutics that requires a greater understanding of the interactions between vascular wall cells and their extracellular matrices. The ubiquitous matrix glycan, hyaluronan (HA), is markedly elevated in lungs from patients and experimental models with PH. Herein, we identified HA synthase-2 (HAS2) in the pulmonary artery smooth muscle cell (PASMC) layer as a predominant locus of HA dysregulation. HA upregulation involves depletion of NUDT21, a master regulator of alternative polyadenylation, resulting in 3'UTR shortening and hyper-expression of HAS2. The ensuing increase of HAS2 and hyper-synthesis of HA promoted bioenergetic dysfunction of PASMC characterized by impaired mitochondrial oxidative capacity and a glycolytic shift. The resulting HA accumulation stimulated pro-remodeling phenotypes such as cell proliferation, migration, apoptosis-resistance, and stimulated pulmonary artery contractility. Transgenic mice, mimicking HAS2 hyper-synthesis in smooth muscle cells, developed spontaneous PH, whereas targeted deletion of HAS2 prevented experimental PH. Pharmacological blockade of HAS2 restored normal bioenergetics in PASMC, ameliorated cell remodeling phenotypes, and reversed experimental PH in vivo. In summary, our results uncover a novel mechanism of HA hyper-synthesis and downstream effects on pulmonary vascular cell metabolism and remodeling.

Purpose: Pulmonary hypertension (PH) is a heterogenous, often progressive disorder leading to right heart failure and death. Previous analyses show stable PH mortality rates from 1980 to 2001 but in-creasing from 2001 to 2010 especially among women and non-Hispanic (NH) Black. This study seeks to identify recent trends in PH mortality in the United States from 1999 to 2019.Methods: Mortality rates among individuals more than or equal to 15 years of age were obtained from the Centers for Disease Control and Prevention's (CDC) Wide-Ranging Online Data for Epidemiology Research (WONDER) database. ICD-10 codes were used to identify individuals with PH.Results: Between 1999 and 2019, PH was included as a cause on 429,105 recorded deaths. The average age-adjusted PH mortality rate was 7.9 per 10 0,0 0 0 individuals and increased by 1.9% per year. Higher age-adjusted mortality rates were experienced by females and NH Black persons. The crude mortality rate was 105.4 per 10 0,0 0 0 among those decedents 85 or older. From 1999 to 2019, mortality in PH and left heart disease co-occurrence increased at nearly double the annual rate of the overall PH group.Conclusions: Despite therapeutic advances for selected PH subgroups, the overall age-adjusted PH mortal-ity rate increased significantly from 1999 to 2019 and previously reported racial disparities have persisted. These findings emphasize the need for additional study to improve outcomes in PH.Published by Elsevier Inc.