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Extracellular Superoxide Dismutase Regulates Early Vascular Hyaluronan Remodeling in Hypoxic Pulmonary Hypertension.

ABSTRACT: Chronic hypoxia leads to pathologic remodeling of the pulmonary vasculature and pulmonary hypertension (PH). The antioxidant enzyme extracellular superoxide dismutase (SOD3) protects against hypoxia-induced PH. Hyaluronan (HA), a ubiquitous glycosaminoglycan of the lung extracellular matrix, is rapidly recycled at sites of vessel injury and repair. We investigated the hypothesis that SOD3 preserves HA homeostasis by inhibiting oxidative and enzymatic hyaluronidase-mediated HA breakdown. In SOD3-deficient mice, hypoxia increased lung hyaluronidase expression and activity, hyaluronan fragmentation, and effacement of HA from the vessel wall of small pulmonary arteries. Hyaluronan fragmentation corresponded to hypoxic induction of the cell surface hyaluronidase-2 (Hyal2), which was localized in the vascular media. Human pulmonary artery smooth muscle cells (HPASMCs) demonstrated hypoxic induction of Hyal2 and SOD-suppressible hyaluronidase activity, congruent to our observations in vivo. Fragmentation of homeostatic high molecular weight HA promoted HPASMC proliferation in vitro, whereas pharmacologic inhibition of hyaluronidase activity prevented hypoxia- and oxidant-induced proliferation. Hypoxia initiates SOD3-dependent alterations in the structure and regulation of hyaluronan in the pulmonary vascular extracellular matrix. These changes occurred soon after hypoxia exposure, prior to appearance of PH, and may contribute to the early pathogenesis of this disease.

SUBMITTER: Tseng V

PROVIDER: S-EPMC6959284 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Extracellular Superoxide Dismutase Regulates Early Vascular Hyaluronan Remodeling in Hypoxic Pulmonary Hypertension.

Tseng Victor V Ni Kevin K Allawzi Ayed A Prohaska Clare C Hernandez-Lagunas Laura L Elajaili Hanan H Cali Valbona V Midura Ronald R Hascall Vincent V Triggs-Raine Barbara B Petrache Irina I Hart C Michael CM Nozik-Grayck Eva E

Scientific reports 20200114 1

Chronic hypoxia leads to pathologic remodeling of the pulmonary vasculature and pulmonary hypertension (PH). The antioxidant enzyme extracellular superoxide dismutase (SOD3) protects against hypoxia-induced PH. Hyaluronan (HA), a ubiquitous glycosaminoglycan of the lung extracellular matrix, is rapidly recycled at sites of vessel injury and repair. We investigated the hypothesis that SOD3 preserves HA homeostasis by inhibiting oxidative and enzymatic hyaluronidase-mediated HA breakdown. In SOD3- ...[more]

PMID: 31937874

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Project description:BACKGROUND:A naturally occurring single nucleotide polymorphism (SNP), (R213G), in extracellular superoxide dismutase (SOD3), decreases SOD3 matrix binding affinity. Humans and mature mice expressing the R213G SNP exhibit increased cardiovascular disease but decreased lung disease. The impact of this SNP on the neonatal lung at baseline or with injury is unknown. METHODS:Wild type and homozygous R213G mice were injected with intraperitoneal bleomycin or phosphate buffered saline (PBS) three times weekly for three weeks and tissue harvested at 22 days of life. Vascular and alveolar development were evaluated by morphometric analysis and immunostaining of lung sections. Pulmonary hypertension (PH) was assessed by right ventricular hypertrophy (RVH). Lung protein expression for superoxide dismutase (SOD) isoforms, catalase, vascular endothelial growth factor receptor 2 (VEGFR2), endothelial nitric oxide synthase (eNOS) and guanosine triphosphate cyclohydrolase-1 (GTPCH-1) was evaluated by western blot. SOD activity and SOD3 expression were measured in serum. RESULTS:In R213G mice, SOD3 lung protein expression decreased, serum SOD3 protein expression and SOD serum activity increased compared to wild type (WT) mice. Under control conditions, R213G mice developed pulmonary vascular remodeling (decreased vessel density and increased medial wall thickness) and PH; alveolar development was similar between strains. After bleomycin injury, in contrast to WT, R213G mice were protected from impaired alveolar development and their vascular abnormalities and PH did not worsen. Bleomycin decreased VEGFR2 and GTPCH-1 only in WT mice. CONCLUSION:R213G neonatal mice demonstrate impaired vascular development and PH at baseline without alveolar simplification, yet are protected from bleomycin induced lung injury and worsening of pulmonary vascular remodeling and PH. These results show that vessel bound SOD3 is essential in normal pulmonary vascular development, and increased serum SOD3 expression and SOD activity prevent lung injury in experimental bronchopulmonary dysplasia (BPD) and PH.

Project description:Chronic hypoxic stress induces epigenetic modifications mainly DNA methylation in cardiac fibroblasts, inactivating tumor suppressor genes (RASSF1A) and activating kinases (ERK1/2) leading to fibroblast proliferation and cardiac fibrosis. The Ras/ERK signaling pathway is an intracellular signal transduction critically involved in fibroblast proliferation. RASSF1A functions through its effect on downstream ERK1/2. The antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), decreases oxidative stress from chronic hypoxia, but its effects on these epigenetic changes have not been fully explored. To test our hypothesis, we used an in-vitro model: wild-type C57B6 male mice (WT) and transgenic males with an extra copy of human hEC-SOD (TG). The studied animals were housed in hypoxia (10% O2) for 21 days. The right ventricular tissue was studied for cardiac fibrosis markers using RT-PCR and Western blot analyses. Primary C57BL6 mouse cardiac fibroblast tissue culture was used to study the in-vitro model, the downstream effects of RASSF-1 expression and methylation, and its relation to ERK1/2. Our findings showed a significant increase in cardiac fibrosis markers: Collagen 1, alpha smooth muscle actin (ASMA), and SNAIL, in the WT hypoxic animals as compared to the TG hypoxic group (p < 0.05). The expression of DNA methylation enzymes (DNMT 1&3b) was significantly increased in the WT hypoxic mice as compared to the hypoxic TG mice (p < 0.001). RASSF1A expression was significantly lower and ERK1/2 was significantly higher in hypoxia WT compared to the hypoxic TG group (p < 0.05). Use of SiRNA to block RASSF1A gene expression in murine cardiac fibroblast tissue culture led to increased fibroblast proliferation (p < 0.05). Methylation of the RASSF1A promoter region was significantly reduced in the TG hypoxic group compared to the WT hypoxic group (0.59 vs. 0.75, respectively). Based on our findings, we can speculate that EC-SOD significantly attenuates RASSF1A gene methylation and can alleviate cardiac fibrosis induced by hypoxia.

Project description:BackgroundHypoxic pulmonary hypertension (HPH) is a chronic progressive advanced disorder pathologically characterized by pulmonary vascular remodeling. Notch4 as a cell surface receptor is critical for vascular development. However, little is known about the role and mechanism of Notch4 in the development of hypoxic vascular remodeling.MethodsLung tissue samples were collected to detect the expression of Notch4 from patients with HPH and matched controls. Human pulmonary artery smooth muscle cells (HPASMCs) were cultured in hypoxic and normoxic conditions. Real-time quantitative PCR and western blotting were used to examine the mRNA and protein levels of Notch4. HPASMCs were transfected with small interference RNA (siRNA) against Notch4 or Notch4 overexpression plasmid, respectively. Cell viability, cell proliferation, apoptosis, and migration were assessed using Cell Counting Kit-8, Edu, Annexin-V/PI, and Transwell assay. The interaction between Notch4 and ERK, JNK, P38 MAPK were analyzed by co-immunoprecipitation. Adeno-associated virus 1-mediated siRNA against Notch4 (AAV1-si-Notch4) was injected into the airways of hypoxic rats. Right ventricular systolic pressure (RVSP), right ventricular hypertrophy and pulmonary vascular remodeling were evaluated.ResultsIn this study, we demonstrate that Notch4 is highly expressed in the media of pulmonary vascular and is upregulated in lung tissues from patients with HPH and HPH rats compared with control groups. In vitro, hypoxia induces the high expression of Delta-4 and Notch4 in HPASMCs. The increased expression of Notch4 promotes HPASMCs proliferation and migration and inhibits cells apoptosis via ERK, JNK, P38 signaling pathways. Furthermore, co-immunoprecipitation result elucidates the interaction between Notch4 and ERK/JNK/P38. In vivo, silencing Notch4 partly abolished the increase in RVSP and pulmonary vascular remodeling caused by hypoxia in HPH rats.ConclusionsThese findings reveal an important role of the Notch4-ERK/JNK/P38 MAPK axis in hypoxic pulmonary remodeling and provide a potential therapeutic target for patients with HPH.

Dataset Information

Extracellular Superoxide Dismutase Regulates Early Vascular Hyaluronan Remodeling in Hypoxic Pulmonary Hypertension.

Publications

Extracellular Superoxide Dismutase Regulates Early Vascular Hyaluronan Remodeling in Hypoxic Pulmonary Hypertension.

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