Identification of Hypoxia Induced Metabolism Associated Genes in Pulmonary Hypertension

Abstract

Objective: Pulmonary hypertension (PH) associated with hypoxia and lung disease (Group 3) is the second most common form of PH and associated with increased morbidity and mortality. This study was aimed to identify hypoxia induced metabolism associated genes (MAGs) for better understanding of hypoxic PH.Methods: Rat pulmonary arterial smooth muscle cells (PASMCs) were isolated and cultured in normoxic or hypoxic condition for 24 h. Cells were harvested for liquid chromatography-mass spectrometry analysis. Functional annotation of distinguishing metabolites was performed using Metaboanalyst. Top 10 enriched metabolite sets were selected for the identification of metabolism associated genes (MAGs) with a relevance score >8 in Genecards. Transcriptomic data from lungs of hypoxic PH in mice/rats or of PH patients were accessed from Gene Expression Omnibus (GEO) database or open-access online platform. Connectivity Map analysis was performed to identify potential compounds to reverse the metabolism associated gene profile under hypoxia stress. The construction and module analysis of the protein-protein interaction (PPI) network was performed. Hub genes were then identified and used to generate LASSO model to determine its accuracy to predict occurrence of PH.Results: A total of 36 altered metabolites and 1,259 unique MAGs were identified in rat PASMCs under hypoxia. 38 differentially expressed MAGs in mouse lungs of hypoxic PH were revealed, with enrichment in multi-pathways including regulation of glucose metabolic process, which might be reversed by drugs such as blebbistatin. 5 differentially expressed MAGs were displayed in SMCs of Sugen 5416/hypoxia induced PH rats at the single cell resolution. Furthermore, 6 hub genes (Cat, Ephx1, Gpx3, Gstm4, Gstm5, and Gsto1) out of 42 unique hypoxia induced MAGs were identified. Higher Cat, Ephx1 and lower Gsto1 were displayed in mouse lungs under hypoxia (all p < 0.05), in consistent with the alteration in lungs of PH patients. The hub gene-based LASSO model can predict the occurrence of PH (AUC = 0.90).Conclusion: Our findings revealed six hypoxia-induced metabolism associated hub genes, and shed some light on the molecular mechanism and therapeutic targets in hypoxic PH.

Animal models of pulmonary hypertension due to left heart disease

“…Considering PH‐LHD caused by myxomatous mitral valve disease occurring in dogs, 73 its predominant echocardiography findings do not support its establishment as a stable model. Although metabolomics has been employed to in vivo models of PH challenged by monocrotaline, hypoxia, or SU5416/hypoxia at the tissue or cellular level or in vitro models (such as pulmonary arterial smooth muscle cells under the stimulus of hypoxia), 74–78 to date, the metabolic reprogramming of animal models mimicking PH‐LHD remains unveiled. Hence the application of metabolomics to the PH‐LHD would provide critical information for our understanding of the metabolic mechanisms underlying PH‐LHD, especially with metabolic perturbations.…”

“…Although an attempt to apply an animal model of volume loading-induced heart failure 72 to the study of PH-LHD has been proposed, its incompatibility with the pathological process of the disease does not yet allow its mainstreaming.Considering PH-LHD caused by myxomatous mitral valve disease occurring in dogs,73 its predominant echocardiography findings do not support its establishment as a stable model. Although metabolomics has been employed to in vivo models of PH challenged by monocrotaline, hypoxia, or SU5416/hypoxia at the tissue or cellular level or in vitro models (such as pulmonary arterial smooth muscle cells under the stimulus of hypoxia),[74][75][76][77][78] to date, the metabolic reprogramming of animal models mimicking PH-LHD remains unveiled. Hence the application of metabolomics to the PH-LHD would provide critical information for our understanding of the metabolic mechanisms underlying PH-LHD, especially with metabolic perturbations.Aside from the triggers of overload-induced LV failure, ischemic heart failure, or metabolic dysfunction, the genetic predisposition to PH-LHD at a large scale will require further investigation with the aid of next-generation sequencing, such as bone morphogenetic protein receptor 2 (BMPR2) as a pivotal predisposing gene for pulmonary arterial hypertension (PAH, group 1 PH).…”

The Role of Glutamine and Glutaminase in Pulmonary Hypertension

“…Hypoxia is considered to be a driver of metabolic conversion and glutamine metabolism in tumor cells (89). One of a recent publication also showed that glutamine and glutamate metabolism was the most remarkable altered metabolism in response to hypoxia in primary rat PASMCs (90). In addition, group 3 PH patients seems to take up more glutamine by the pulmonary vasculature compared to controls (33).…”

Regulatory T Cell-Related Gene Indicators in Pulmonary Hypertension

“…The pathogenesis of PH is driven or initiated by multiple elements such as genetic predisposition ( Morrell et al, 2019 ; Wang et al, 2020 ), epigenetic alterations ( Potus et al, 2020 ; Yan et al, 2020 ; Wang Q. et al, 2022 ), inflammation ( Rabinovitch et al, 2014 ; Liang et al, 2021 ), altered metabolism ( He et al, 2020 ; He Y.-y. et al, 2021 ; Xu et al, 2021 ; Wang S. et al, 2022 ), and environmental cues such as hypoxia ( He Y.-Y. et al, 2021 ) and growth factors ( Yan et al, 2021 ).…”