Vascular Dysfunction and Inflammation

Clinical Center

Investigators

Linked publications, trials & patents

Abstract

Nitric oxide (NO): NO upregulates TNFa production (J Immunol 1994; Blood 1997) through a cGMP-independent pathway (J Biol Chem 1997; J Biol Chem 1999; J Biol Chem 2003), while ROS from eNOS uncoupling upregulates TNFa (J Biol Chem 2000) through ERK1/2 (Am J Physiol 2001). NO activation of p38 MAPK stabilizes IL-8 mRNA (J Infect Dis 1998; J Leuk Biol 2004) and p21 mRNA, an antiproliferative effect (BMC Genomics 2005; J Biol Chem 2006). NO activates PPARg through p38 MAPK (FASEB J 2007) protecting the endothelium. NO has diverse effects on transcript stability and translation (Nucleic Acids Research 2006; J Leuk Biol 2008). Unlike NO, CO blocked NF-kB signaling, broadly suppressing inflammation (PLoS One 2009). Sickle cell disease via NO scavenging causes vascular oxidant and inflammatory stress (Blood, 2004), altering gene expression and arginine metabolism (Circulation, 2007). Cell-free-hemoglobin (CFH) scavenging of NO causes pulmonary hypertension, cardiogenic shock, and multiorgan failure. During sepsis, CFH infusions also promoted bacterial growth, contributing to lung injury. As such, CFH elevation in septic shock adversely impacts sepsis outcomes (Am J Physiol Heart Circ Physiol 2021). Nuclear receptors (NRs): GPR40/p38 MAPK/PGC1a/EP300 activation was shown to augment rosiglitazone (RGZ)/PPARg genomic signaling (J Biol Chem 2015). Cognate GPR and nuclear receptor signaling networks may explain differences in the safety and efficacy of NR targeted drugs (Pharm Research 2016). Long-chain monounsaturated fatty acids (LCMUFA; i.e., C20:1 and C22:1) activate PPAR via GPR40 (Atherosclerosis 2017). MR agonists repress NF-kB mediated gene transcription, but trans-activate AP-1 signaling in a DNA sequence, MR conformation, and AP-1 family member dependent fashion (J Biol Chem 2016). Aldosterone/MR activation of AP-1 contribute to harm in CHF and PAH. Spironolactone (SPL) suppresses both NF-kB and AP-1 inflammatory signaling independent of MR through proteasomal degradation of XPB, a TFIIH subunit (Cardiovasc Res 2018). Pulmonary arterial hypertension (PAH): A pilot study of SPL therapy (Trials 2013) and a natural history study investigating vascular inflammation support ongoing laboratory studies. Circulating ECs were identified and validated using flow cytometry and ultramicroanalytical immunochemistry (Thromb Haemostasis 2014). A meta-analysis of PBMC expression profiling in PAH patients identified IFN-driven inflammation as a fundamental component of PAH pathobiology (Am J Physiol Lung Cell Mol Physiol 2020). MR antagonist treatment in the SuHx rat model of PAH preserved cardiac index and increased left ventricular (LV) end-diastolic volume, blunting the induction of MR target and inflammatory genes in the RV (Am J Physiol Lung Cell Mol Physiol 2022). Loss-of-function mutations in BMPR2 are the most common genetic cause of PAH. BMPR2 knockdown (KD) in human PAECs activated Ras/Raf/ERK signaling, proliferation, and invasiveness, effects associated with cytoskeletal abnormalities (Am J Physiol Lung Cell Mol Physiol 2016). Resistance to apoptosis has been a consistent feature of our EC models of PAH. In our BMPR2 LOF model, apoptosis resistance was linked to DLL4/NOTCH1 signaling loss with PI3K/AKT activation, and JNK suppression (Aspen Lung Conference 2019). Importantly, DLL4 loss was validated in lung tissue from iPAH patients. Blocking PI3K/AKT or overexpressing PPARgamma restored apoptosis sensitivity in three model systems, BMPR2, CAV1 and PHD2 (ATS abstract 2023; Int J Mol Sci. 2024). Interactions among BMPR2, DLL4/NOTCH1/PPAR, and PI3K/AKT may lead to targeted approaches for treating vascular remodeling in PAH. CAV1 LOF, like BMPR2, produced a proliferative, hyper-migratory and inflammatory PAEC phenotype associated with JAK/STAT/interferon and AKT activation. This inflammatory signature was also found in fibroblasts from PAH patients with CAV1 mutations and in CAV1-/- mice. CAV1 loss and STAT1 activation was also seen in the pulmonary arterioles of patients with iPAH. Blocking JAK/STAT or AKT rescued aspects of CAV1 loss. Silencing endothelial NO synthase (NOS3) prevented STAT1 and AKT activation induced by CAV1 loss, and diminished ROS generation implicating CAV1/NOS3 uncoupling (Proc Natl Acad Sci USA 2021). Small molecule inhibitors of sAC and PKA blocked NOS3 and STAT1 phosphorylation suggesting a possible role for this pathway in CAV1 loss associated abnormalities (ATS abstracts 2022 and 2024). COUPTF2 (NR2F2) LOF mutations have been associated with CHD, which can result in PAH. COUPTF2 silencing in ECs produced an IFN inflammatory response and a hyper-proliferative, apoptosis-resistant, and invasive phenotype. Dickkopf-1 (DKK1) was induced by COUPTF2 loss and DKK1 knockdown abrogated signaling and phenotypic abnormalities (Am J Physiol Lung Cell Mol Physiol 2023). An in vitro pseudohypoxia model of PAH was established by silencing PHD2 (prolyl hydroxylase domain protein 2; EGLN1) in LMVECs. PHD2 deficiency drives an apoptosis-resistant, inflammatory EC phenotype, mediated by AKT activation and ASK-interacting protein 1 (AIP1; DAB2IP) loss, independent of HIF signaling (Aspen Lung Conference 2019; Am J Physiol Lung Cell Mol Physiol 2024) SMAD8 LOF in human PAECs also produced an abnormal cellular phenotype characterized by proliferation, hypermigration, cytoskeletal and mitochondrial alterations and endothelial to mesenchymal transition, as well as non-canonical activation of AKT, ERK and p38 (ATS 2018). Vasohibin-1 (VASH1) loss with increased alpha-tubulin tyrosination was implicated in BMPR2 loss-associated cytoskeletal abnormalities and endothelial dysfunction. VASH1/α-tubulin detyrosination loss activates AKT, ERK, proliferation, cell migration, and apoptosis resistance. Co-silencing TTL increases detyrosinated α-tubulin , blocking both ERK and AKT activation. BMPR2 and TTL silencing have opposite effects on the expression of >600 genes regulated by the tyrosination state of the endothelial cytoskeleton. This unexplored mechanism may lead to novel therapeutic approaches for preventing or reversing pathologic vascular remodeling in PAH (Grover ATS Conference abstract 2025; MS in preparation). Obesity-related metabolic stressors including elevated leptin, oxidative stress, chronic inflammation, and endothelial cell (EC) dysfunction are cardiovascular risk factors that also affect pulmonary vascular remodeling. While metabolic syndrome and some forms of lipodystrophy (i.e. CAV1 loss-of-function mutations) are linked to an increased risk of PAH, other studies have suggested that obesity confers a survival benefit, a phenomenon known as the "obesity paradox." We are investigating leptin and GDF15, an inflammatory adipokine regulated by leptin and elevated in PAH, to better understand the role of obesity and obesity-associated sex differences in PAH (2025 Bench to Bedside and Back application; Vascular Discovery AHA abstract 2025; Grover ATS Conference abstract 2025). COVID-19 Vasculopathy: Low expression of ACE2 and TMPRSS2 in PAECs may explain their diminished susceptibility to SARS-CoV-2 (ATS abstract 2022). Endothelial senescence rather than direct infectioin may underlie the thrombotic microvasculopathy associated with severe COVID-19 as well as the increased risk of cardiovascular events in patients who have otherwise recovered. We have launched a multi-institute project to investigate this hypothesis using patient cohorts, a bioengineered three-dimensional disease-on-chip in vitro system and a mouse model (Bench to Bedside and Back Award 2023). SARS-CoV-2 viral proteins are readily taken up by human endothelium and trigger a senescent cellular phenotype (NIH Research Festival 2023; Fellows Award for Research Excellence 2024; Vascular Discovery AHA abstracts 2025). Endothelial senescence in this model system is reversible using fostamatinib, a drug tested at the NIHCC for acute COVID-19.