Increased expression of hypoxia-inducible factor-1α in proliferating neointimal lesions in a rat model of pulmonary arterial hypertension

Glycometabolism reprogramming: Implications for cardiovascular diseases

Glycometabolism is well known for its roles as the main source of energy, which mainly includes three metabolic pathways: oxidative phosphorylation, glycolysis and pentose phosphate pathway. The orderly progress of glycometabolism is the basis for the maintenance of cardiovascular function. However, upon exposure to harmful stimuli, the intracellular glycometabolism changes or tends to shift toward another glycometabolism pathway more suitable for its own development and adaptation. This shift away from the normal glycometabolism is also known as glycometabolism reprogramming, which is commonly related to the occurrence and aggravation of cardiovascular diseases. In this review, we elucidate the physiological role of glycometabolism in the cardiovascular system and summarize the mechanisms by which glycometabolism drives cardiovascular diseases, including diabetes, cardiac hypertrophy, heart failure, atherosclerosis, and pulmonary hypertension. Collectively, directing GMR back to normal glycometabolism might provide a therapeutic strategy for the prevention and treatment of related cardiovascular diseases.

Novel Targets in a High-Altitude Pulmonary Hypertension Rat Model Based on RNA-seq and Proteomics

High-altitude pulmonary hypertension (HAPH) is a complication arising from an inability to acclimatize to high altitude and is associated with high morbidity and mortality. We aimed to analyze the effects of macitentan, selexipag, riociguat, and reoxygenation on HAPH, and to screen possible targets of these treatments for future drug screening. Rats were subjected to hypobaric hypoxia for 35 days to induce HAPH, and treated with vehicle or selexipag, macitentan, riociguat, or with reoxygenation, from days 21 to 35. Selexipag, macitentan, and reoxygenation prevented an increase in mean pulmonary artery pressure and hypoxia-induced right ventricular hypertrophy, compared to the vehicle. Riociguat had little effect. RNA-seq and proteomics revealed strong correlations between responses to the three drugs, which had almost identical effects. GO-enrichment revealed that the differentially expressed genes included those involved in metabolic regulation, transcription, and translation. Various molecular pathways were annotated. Selexipag, macitentan, and reoxygenation ameliorated HAPH. Serpina1, Cryz, and Cmc1 were identified, via multi-omics screening, as key genes involved in HAPH. These findings provide new insights into the targeted drug mechanisms in HAPH.

Transgenerational inheritance of promoter methylation changes in extrauterine growth restriction-induced pulmonary arterial pressure disorders

Background

This study aimed to investigate the influence of extrauterine growth restriction (EUGR) on pulmonary arterial pressure (PAP) and the transgenerational inheritance of promoter methylation changes in pulmonary vascular endothelial cells (PVECs) of 2 consecutive generations under EUGR stress.

Methods

After modeling, PAP values of F1 and F2 pups were investigated at 9-week-old. The methyl-DNA immune precipitation chip was used to analyze DNA methylation profiling. Differential enrichment peaks (DEPs) and regions of interest (ROIs) were identified, based on which Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and reactome pathway enrichments were analyzed.

Results

The F1 male rats in the EUGR group had significantly increased PAP levels compared to the control group; however, this increase was not observed in female rats. Interestingly, in F2 female rats, the EUGR group had decreased PAP. In the X chromosome of the F1 males, there were 16 differential ROI genes in the F1 generation, while in F2 females, there were 86 differential ROI genes. Similarly, there were 105 DEPs in the F1 generation and 38 DEPs in the F2 generation. In combination with the 5 common ROIs and 14 common DEPs, 18 genes were regarded as the key candidate genes associated with hereditable PAP variation in the EUGR model. Enrichment analysis showed that synaptic and neurotransmitter relative pathways might be involved in the process of EUGR-induced PAH development. Among common DEPs, Smad1 and Serpine1 were also found in 102 PAH-associated genes in the MalaCards database.

Conclusions

Together, there is a transgenerational inheritance of promoter methylation changes in the X chromosome in EUGR-induced PAP disorders, which involves the participation of synaptic and neurotransmitter relative pathways. Also, attenuated methylation of Smad1 and Serpine1 in the promoter region may be a partial driver of PAH in later life.

3-Bromopyruvate Attenuates Experimental Pulmonary Hypertension via Inhibition of Glycolysis

BACKGROUND

The shift of metabolism from mitochondrial oxidative phosphorylation to glycolysis and mitochondria binding partner of hexokinase are features common to cancer. These have been seen in pulmonary hypertension (PH) as well. An inhibitor of hexokinase 2 (HK 2), the small molecule 3-bromopyruvate (3-BrPA) is an incredibly powerful and swift-acting anticancer agent. However, whether it could be of potential benefit to PH has still been unknown.

METHODS

Sprague-Dawley rats with monocrotaline (MCT)-induced PH were administered 2 oral doses of 3-BrPA (15 and 30 mg/kg/day, respectively) for 14 days. Hemodynamic parameters were obtained by right heart catheterization. Histopathology, immunohistochemistry, transmission electron microscopy, flow cytometry, and assessments of relative protein expressions were conducted.

RESULTS

Compared with MCT treatment, 3-BrPA decreased mean pulmonary arterial pressure and pulmonary vascular resistance, and increased cardiac output. 3-BrPA significantly suppressed proliferation in addition to enhancing apoptosis of pulmonary artery smooth muscle cells, attenuating small pulmonary artery remodeling and right ventricular hypertrophy. Treatment with 3-BrPA markedly reduced the mitochondrial membrane potential and restored mitochondrial structure. Furthermore, 3-BrPA significantly inhibited HK 2 expression but not HK 1. The expression of both pyruvate dehydrogenase kinase and lactate dehydrogenase was decreased whereas that of pyruvate dehydrogenase and cytosolic cytochrome c was upregulated with 3-BrPA administration.

CONCLUSION

This study demonstrates the reversal of PH by 3-BrPA is related to alteration in glycolysis and improved mitochondria function, indicating the "metabolic targeting" as a rational therapeutic strategy for PH.

Reversal of the Warburg effect with DCA in PDGF‑treated human PASMC is potentiated by pyruvate dehydrogenase kinase‑1 inhibition mediated through blocking Akt/GSK‑3β signalling

There is accumulating evidence indicating that the growth inhibitory effect of dichloroacetate (DCA) on pulmonary arterial smooth muscle cells (PASMCs) may be associated with the reversal of the Warburg effect and initiation of the mitochondria-dependent apoptotic pathway. Previous studies indicated that platelet-derived growth factor (PDGF) promoted the Warburg effect and resulted in apoptotic resistance of PASMCs, which was attributed to activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signalling pathway. However, the mechanism underlying the pro-apoptotic effect of DCA on PDGF-treated PASMCs has not been thoroughly elucidated, and the effect of the Akt/glycogen synthase kinase-3β (GSK-3β) pathway inhibition concomitant with the effect of DCA on PASMC proliferation remains unclear. The growth of human PASMCs and the lactate concentration in extracellular medium of PASMCs were detected by Cell Counting Kit-8 assays and a Lactate Colorimetric Assay kit, respectively. Cell apoptosis was evaluated by fluorescence activated cell sorting. The mitochondrial membrane potential (ΔΨm) was assessed with 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazol-carbocy-anine iodide assays. The expression levels of phosphorylated Akt and GSK-3β, pyruvate dehydrogenase, cleaved caspase-3, pyruvate dehydrogenase kinase-1 (PDK-1), hypoxia inducible factor-1α (HIF-1α) and hexokinase-2 (HK-2) were measured with western blot analysis. Confocal analyses were employed to determine HK-2 co-localisation with the mitochondria. The results indicated that DCA inhibited human PASMC proliferation in a dose-dependent manner. DCA at 10 mM promoted apoptosis and the upregulation of activated caspase-3 in PASMCs pre-treated with 20 ng/ml PDGF-homeodimer BB (BB). Treatment with 5 µM LY294002 produced minimal anti-proliferative effects on human PASMCs and barely induced cellular apoptosis and caspase-3 activation. However, co-administration of 10 mM DCA with LY294002 significantly decreased the cell proliferation index and induced cell apoptosis and caspase-3 activation. The combined administration of LY294002 with DCA significantly decreased lactate concentration, promoted the depolarisation of the ΔΨm and repressed HIF-1α upregulation and HK-2 activation in PASMCs treated with PDGF, which was attributed to the potentiation of DCA-induced PDK-1 inhibition by LY294002 via blockade of the Akt/GSK-3β/HIF-1α signalling pathway. In conclusion, inhibition of the Akt/GSK-3β pathway improved the pro-apoptotic effect of DCA on human PASMCs, which may be attributed to a reversal of the Warburg effect by blocking the mutual interaction between HIF-1α and PDK-1, consequently downregulating HK-2. Therefore, combinatory treatment with DCA and PI3K inhibitors may represent a novel therapeutic strategy for the reversal of apoptosis resistance exhibited by PASMCs as a result of mitochondrial bioenergetic abnormalities, as well as the treatment of pulmonary vascular remodelling in pulmonary arterial hypertension.

Survivin in autoimmune diseases

Survivin is a protein functionally important for cell division, apoptosis, and possibly, for micro-RNA biogenesis. It is an established marker of malignant cell transformation. In non-malignant conditions, the unique properties of survivin make it indispensable for homeostasis of the immune system. Indeed, it is required for the innate and adaptive immune responses, controlling differentiation and maintenance of CD4⁺ and CD8⁺ memory T-cells, and in B cell maturation. Recently, survivin has emerged as an important player in the pathogenesis of autoimmune diseases. Under the conditions of unreserved inflammation, survivin enhances antigen presentation, maintains persistence of autoreactive cells, and supports production of autoantibodies. In this context, survivin takes its place as a diagnostic and prognostic marker in rheumatoid arthritis, psoriasis, systemic sclerosis and pulmonary arterial hypertension, neuropathology and multiple sclerosis, inflammatory bowel diseases and oral lichen planus. In this review, we summarise the knowledge about non-malignant properties of survivin and focus on its engagement in cellular and molecular pathology of autoimmune diseases. The review highlights utility of survivin measures for clinical applications. It provides rational for the survivin inhibiting strategies and presents results of recent reports on survivin inhibition in modern therapies of cancers and autoimmune diseases.

miR-17/20 Controls Prolyl Hydroxylase 2 (PHD2)/Hypoxia-Inducible Factor 1 (HIF1) to Regulate Pulmonary Artery Smooth Muscle Cell Proliferation

Background

Previously we found that smooth muscle cell (SMC)‐specific knockout of miR‐17~92 attenuates hypoxia‐induced pulmonary hypertension. However, the mechanism underlying miR‐17~92‐mediated pulmonary artery SMC (PASMC) proliferation remains unclear. We sought to investigate whether miR‐17~92 regulates hypoxia‐inducible factor (HIF) activity and PASMC proliferation via prolyl hydroxylases (PHDs).

Methods and Results

We show that hypoxic sm‐17~92^−/− mice have decreased hematocrit, red blood cell counts, and hemoglobin contents. The sm‐17~92^−/− mouse lungs express decreased mRNA levels of HIF targets and increased levels of PHD2. miR‐17~92 inhibitors suppress hypoxia‐induced levels of HIF1α, VEGF, Glut1, HK2, and PDK1 but not HIF2α in vitro in PASMC. Overexpression of miR‐17 in PASMC represses PHD2 expression, whereas miR‐17/20a inhibitors induce PHD2 expression. The 3′‐UTR of PHD2 contains a functional miR‐17/20a seed sequence. Silencing of PHD2 induces HIF1α and PCNA protein levels, whereas overexpression of PHD2 decreases HIF1α and cell proliferation. SMC‐specific knockout of PHD2 enhances hypoxia‐induced vascular remodeling and exacerbates established pulmonary hypertension in mice. PHD2 activator R59949 reverses vessel remodeling in existing hypertensive mice. PHDs are dysregulated in PASMC isolated from pulmonary arterial hypertension patients.

Conclusions

Our results suggest that PHD2 is a direct target of miR‐17/20a and that miR‐17~92 contributes to PASMC proliferation and polycythemia by suppression of PHD2 and induction of HIF1α.

Values of hemodynamic variation in response to passive leg raising in predicting exercise capacity of heart failure with preserved ejection fraction

In heart failure patients with preserved ejection fraction, their hemodynamic parameters usually change when they are from recumbent to passive leg raising. The authors designed this study to investigate the relationship between hemodynamic parameters measured by impedance cardiography (ICG) and 6-minute walk distance (6MWD) of heart failure with preserved ejection fraction (HFPEF). We recruited 49 subjects with HFPEF in the study, and all the subjects were separated into 2 groups: the patients whose hemodynamic parameters rose after passive leg raising were in group 1 (n = 26) and the patients whose hemodynamic parameters did not rise after passive leg raising were in group 2 (n = 23). Our study then compared the 6MWD, left ventricular ejection fraction, and plasma NT-pro-brain natriuretic peptide between the 2 groups. Group 1 had significantly longer 6MWD than group 2 (515.38 ± 24.97 vs 306.39 ± 20.20 m; P = 0.043). Hemodynamic parameters measured by ICG significantly correlated with 6MWD in both groups. Patients whose hemodynamic parameters rose in response to passive leg raising were more likely to have better exercise capacity. Hemodynamic variation in response to passive leg raising measured by ICG may be more sensitive in predicting exercise capacity of patients with HFPEF.

Expression of mutant bone morphogenetic protein receptor II worsens pulmonary hypertension secondary to pulmonary fibrosis

Pulmonary fibrosis is often complicated by pulmonary hypertension (PH), and previous studies have shown a potential link between bone morphogenetic protein receptor II (BMPR2) and PH secondary to pulmonary fibrosis. We exposed transgenic mice expressing mutant BMPR2 and control mice to repetitive intraperitoneal injections of bleomycin for 4 weeks. The duration of transgene activation was too short for mutant BMPR2 mice to develop spontaneous PH. Mutant BMPR2 mice had increased right ventricular systolic pressure compared to control mice, without differences in pulmonary fibrosis. We found increased hypoxia-inducible factor (HIF)1-α stabilization in lungs of mutant-BMPR2-expressing mice compared to controls following bleomycin treatment. In addition, expression of the hypoxia response element protein connective tissue growth factor was increased in transgenic mice as well as in a human pulmonary microvascular endothelial cell line expressing mutant BMPR2. In mouse pulmonary vascular endothelial cells, mutant BMPR2 expression resulted in increased HIF1-α and reactive oxygen species production following exposure to hypoxia, both of which were attenuated with the antioxidant TEMPOL. These data suggest that expression of mutant BMPR2 worsens secondary PH through increased HIF activity in vascular endothelium. This pathway could be therapeutically targeted in patients with PH secondary to pulmonary fibrosis.