Alpha-enolase regulates the malignant phenotype of pulmonary artery smooth muscle cells via the AMPK-Akt pathway

Macrophage-specific κ-OR knockout exacerbates inflammation in hypoxic pulmonary hypertension

Hypoxic pulmonary hypertension (HPH), a prevalent subtype of pulmonary arterial hypertension, is characterized by pulmonary vasoconstriction (HPV) and vascular remodeling, accompanied by inflammatory responses. Recent in vivo studies have shown a critical role of the κ-opioid receptor (κ-OR) in modulating the aforementioned pathological processes. Specifically, macrophage-specific κ-OR-knockout models have shown inflammatory response exacerbation with pulmonary hypertension and vascular remodeling. Conversely, the novel κ-OR agonist Q-U50, 488H inhibits inflammatory pathways, thereby attenuating pulmonary vasoconstriction and vascular remodeling. The present study revealed that hypoxia promoted macrophage infiltration and pulmonary artery smooth muscle cell proliferation. Moreover, under these conditions, macrophages secreted interleukin (IL)-6, which triggered the signal transducer and activator of transcription 3 (STAT3)/miR-153-3p signaling cascade. Herein, we identified miR-153-3p downregulated κ-OR gene expression, which is a key contributor to HPV and remodeling, it was identified as a pivotal regulator of κ-OR mRNA levels. The pharmacological activation of κ-OR inhibited IL-6 release from macrophages and disrupted the IL-6/STAT3/miR-153-3p pathway. This dual action of κ-OR activation mitigated pulmonary artery contraction and remodeling, thereby offering a protective mechanism against HPH. The present findings have delineated a novel negative feedback loop driving HPH pathogenesis and suggested that targeting the κ-OR-IL-6-STAT3-miR-153-3p axis represented a promising therapeutic strategy against HPH.

Dehydrodiisoeugenol inhibits PDGF-BB-induced proliferation and migration of human pulmonary artery smooth muscle cells via the mTOR/HIF1-α/HK2 signaling pathway

Abnormal proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) leading to pulmonary vascular remodeling are critical factors in the development of pulmonary hypertension (pH). Dehydrodiisoeugenol (DEH), a natural phenolic compound, is renowned for its antioxidant and anti-inflammatory properties. However, the precise role and mechanisms of DEH in PH remain unclear. In this study, human PASMCs were exposed to PDGF-BB for 48 h to establish an in vitro model. Subsequently, cells were treated with DEH, and assessments of cell proliferation, migration, and apoptosis were performed using CCK-8/EdU assays, scratch/transwell assays, and flow cytometry. The results showed that PDGF-BB induced phenotypic modulation, proliferation, and migration of PASMCs while reducing apoptosis. Treatment with DEH effectively reversed these effects. Bioinformatics analysis identified mTOR as a target of DEH action. Western blot experiments were conducted to evaluate the expression of proteins involved in the mTOR/HIF1-α/HK2 signaling pathway, suggesting that DEH modulates this pathway by targeting and inhibiting mTOR. After treating cells with mTOR inhibitors, cellular glycolysis was assessed using the extracellular acidification rate (ECAR) assay. The results indicated that inhibition of mTOR phosphorylation decreased aerobic glycolysis in PASMCs and suppressed cell proliferation, migration, and apoptosis resistance, regardless of PDGF-BB treatment. Activation of mTOR reversed the inhibition of PDGF-BB-induced PASMC-related protein expression by DEH. These findings suggest that DEH inhibits aerobic glycolysis in PDGF-BB-induced PASMCs through the mTOR/HIF1-α/HK2 signaling pathway, thereby suppressing cell proliferation, migration, and resistance to apoptosis. Consequently, DEH holds promise as a novel therapeutic agent for treating pulmonary arterial hypertension.

Superenhancer-driven circRNA Myst4 involves in pulmonary artery smooth muscle cell ferroptosis in pulmonary hypertension

The abnormal expression of circular RNAs (circRNAs) is emerging as a critical cause in regulation of pathological changes of hypoxic pulmonary hypertension (PH), in which ferroptosis is a new pathological change reported recently. However, how circRNAs regulate ferroptosis remains unclear. Here, we proved a significant decrease in circMyst4 expression in hypoxia. In vitro assays revealed that circMyst4 alleviated hypoxic pulmonary artery smooth muscle cell (PASMC) ferroptosis through directly combing with DDX5 in the nucleus to promote GPX4 mRNA processing and inhibiting the formation of the Eef1a1/ACSL4 complex in the cytoplasm. Additionally, superenhancer (SE) was verified to drive the generation of circMyst4. In vivo assays revealed that circMyst4 inhibited the progression of hypoxic PH. Overall, SE-driven circMyst4 may be a new potential therapeutic target for mediating PASMC ferroptosis through promoting DDX5-regulated GPX4 mRNA processing and inhibiting the binding between Eef1a1 and ACSL4.

The effects of sodium-glucose cotransporter 2 inhibitors on the 'forgotten' right ventricle

With the progress in diagnosis, treatment and imaging techniques, there is a growing recognition that impaired right ventricular (RV) function profoundly affects the prognosis of patients with heart failure (HF), irrespective of their left ventricular ejection fraction (LVEF). In addition, right HF (RHF) is a common complication associated with various diseases, including congenital heart disease, myocardial infarction (MI), pulmonary arterial hypertension (PAH) and dilated cardiomyopathy (DCM), and it can manifest at any time after left ventricular assist devices (LVADs). The sodium-glucose cotransporter 2 (SGLT2) inhibition by gliflozins has emerged as a cornerstone medicine for managing type 2 diabetes mellitus (T2DM) and HF, with an increasing focus on its potential to enhance RV function. In this review, we aim to present an updated perspective on the pleiotropic effects of gliflozins on the right ventricle and offer insights into the underlying mechanisms. We can ascertain their advantageous impact on the right ventricle by discussing the evidence obtained in animal models and monumental clinical trials. In light of the pathophysiological changes in RHF, we attempt to elucidate crucial mechanisms regarding their beneficial effects, including alleviation of RV overload, reduction of hyperinsulinaemia and inflammatory responses, regulation of nutrient signalling pathways and cellular energy metabolism, inhibition of oxidative stress and myocardial fibrosis, and maintenance of ion balance. Finally, this drug class's potential application and benefits in various clinical settings are described, along with a prospective outlook on future clinical practice and research directions.

MFN2-dependent mitochondrial dysfunction contributes to Relm-β-induced pulmonary arterial hypertension via USP18/Twist1/miR-214 pathway

Induction of resistin-like molecule β (Relm-β) and mitofusin 2 (MFN2) mediated aberrant mitochondrial fission have been found to be involved in the pathogenesis of pulmonary arterial hypertension (PAH). However, the molecular mechanisms underlying Relm-β regulation of MFN2 therefore mitochondrial fission remain unclear. This study aims to address these issues. Primary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. The results showed that Relm-β promoted cells proliferation in PASMCs, this was accompanied with the upregulation of USP18, Twist1 and miR-214, and downregulation of MFN2. We found that Relm-β increased USP18 expression which in turn raised Twist1 by suppressing its proteasome degradation. Elevation of Twist1 increased miR-214 expression and then reduced MFN2 expression and mitochondrial fragmentation leading to PASMCs proliferation. In vivo study, we confirmed that Relm-β was elevated in MCT-induced PAH rat model, and USP18/Twist1/miR-214/MFN2 axis was altered similar as in vitro. Targeting this cascade by Relm-β receptor inhibitor Calhex231, proteasome inhibitor MG-132, Twist1 inhibitor Harmine or miR-214 antagomiR prevented the development of pulmonary vascular remodeling and therefore PAH in MCT-treated rats. In conclusion, we demonstrate that Relm-β promotes PASMCs proliferation and vascular remodeling by activating USP18/Twist1/miR-214 dependent MFN2 reduction and mitochondrial fission, suggesting that this signaling pathway might be a promising target for management of PAH.

Molecular Cloning, Prokaryotic Expression, and Immunological Characterization of β-Enolase from Grass Carp (Ctenopharyngodon idella)

β-Enolase is a cross-allergen commonly found in fungi, plants, and aquatic products. Although studies on the allergenicity of fish enolase have been reported in recent years, they are still limited to a few species of marine fish. Therefore, the detection of freshwater fish in the food industry requires more studies of the molecular characterization as well as the allergenicity of enolase. In this study, the nucleotide sequence of β-enolase from grass carp was obtained by molecular cloning technology. Structural domain analysis showed that it contained the characteristic structural domains of the enolase superfamily, and homology analysis indicated that enolases are highly conserved evolutionarily. Recombinant β-enolase was obtained by prokaryotic expression, and its allergenicity was assessed by β-enolase-sensitized mice, which confirmed the ability of β-enolase to trigger an allergic response and cause a rise in Th1 and Th2 immune responses in mice. These results suggest that β-enolase could be used as a characterizing substance for the detection of fish allergens in the food industry as well as the preparation of drugs for allergy-related studies.

Enhanced glycolysis causes extracellular acidification and activates acid-sensing ion channel 1a in hypoxic pulmonary hypertension

In pulmonary hypertension (PHTN), a metabolic shift to aerobic glycolysis promotes a hyperproliferative, apoptosis-resistant phenotype in pulmonary arterial smooth muscle cells (PASMCs). Enhanced glycolysis induces extracellular acidosis, which can activate proton-sensing membrane receptors and ion channels. We previously reported that activation of the proton-gated cation channel acid-sensing ion channel 1a (ASIC1a) contributes to the development of hypoxic PHTN. Therefore, we hypothesize that enhanced glycolysis and subsequent acidification of the PASMC extracellular microenvironment activate ASIC1a in hypoxic PHTN. We observed decreased oxygen consumption rate and increased extracellular acidification rate in PASMCs from chronic hypoxia (CH)-induced PHTN rats, indicating a shift to aerobic glycolysis. In addition, we found that intracellular alkalization and extracellular acidification occur in PASMCs following CH and in vitro hypoxia, which were prevented by the inhibition of glycolysis with 2-deoxy-d-glucose (2-DG). Inhibiting H+ transport/secretion through carbonic anhydrases, Na+/H+ exchanger 1, or vacuolar-type H+-ATPase did not prevent this pH shift following hypoxia. Although the putative monocarboxylate transporter 1 (MCT1) and -4 (MCT4) inhibitor syrosingopine prevented the pH shift, the specific MCT1 inhibitor AZD3965 and/or the MCT4 inhibitor VB124 were without effect, suggesting that syrosingopine targets the glycolytic pathway independent of H+ export. Furthermore, 2-DG and syrosingopine prevented enhanced ASIC1a-mediated store-operated Ca2+ entry in PASMCs from CH rats. These data suggest that multiple H+ transport mechanisms contribute to extracellular acidosis and that inhibiting glycolysis-rather than specific H+ transporters-more effectively prevents extracellular acidification and ASIC1a activation. Together, these data reveal a novel pathological relationship between glycolysis and ASIC1a activation in hypoxic PHTN.NEW & NOTEWORTHY In pulmonary hypertension, a metabolic shift to aerobic glycolysis drives a hyperproliferative, apoptosis-resistant phenotype in pulmonary arterial smooth muscle cells. We demonstrate that this enhanced glycolysis induces extracellular acidosis and activates the proton-gated ion channel, acid-sensing ion channel 1a (ASIC1a). Although multiple H+ transport/secretion mechanisms are upregulated in PHTN and likely contribute to extracellular acidosis, inhibiting glycolysis with 2-deoxy-d-glucose or syrosingopine effectively prevents extracellular acidification and ASIC1a activation, revealing a promising therapeutic avenue.

A multimodal approach identifies lactate as a central feature of right ventricular failure that is detectable in human plasma

Background

In PAH metabolic abnormalities in multiple pathways are well-recognized features of right ventricular dysfunction, however, prior work has focused mainly on the use of a single "omic" modality to describe a single deranged pathway. We integrated metabolomic and epigenomic data using transcriptomics in failing and non-failing RVs from a rodent model to provide novel mechanistic insight and translated these findings to accessible human specimens by correlation with plasma from PAH patients.

Methods

Study was conducted in a doxycycline-inducible BMPR2 mutant mouse model of RV failure. Plasma was collected from controls and PAH patients. Transcriptomic and metabolomic analyses were done on mouse RV tissue and human plasma. For mouse RV, we layered metabolomic and transcriptomic data for multiple metabolic pathways and compared our findings with metabolomic and transcriptomic data obtained for human plasma. We confirmed our key findings in cultured cardiomyocyte cells with BMPR2 mutation.

Results

In failing mouse RVs, (1) in the glycolysis pathway, glucose is converted to lactate via aerobic glycolysis, but may also be utilized for glycogen, fatty acid, and nucleic acid synthesis, (2) in the fatty acid pathway, FAs are accumulated in the cytoplasm because the transfer of FAs to mitochondria is reduced, however, the ß-oxidation pathway is likely to be functional. (3) the TCA cycle is altered at multiple checkpoints and accumulates citrate, and the glutaminolysis pathway is not activated. In PAH patients, plasma metabolic and transcriptomic data indicated that unlike in the failing BMPR2 mutant RV, expression of genes and metabolites measured for the glycolysis pathway, FA pathway, TCA cycle, and glutaminolysis pathway were increased. Lactate was the only metabolite that was increased both in RV and circulation. We confirmed using a stable isotope of lactate that cultured cardiomyocytes with mutant BMPR2 show a modest increase in endogenous lactate, suggesting a possibility of an increase in lactate production by cardiomyocytes in failing BMPR2 mutant RV.

Conclusion

In the failing RV with mutant BMPR2, lactate is produced by RV cardiomyocytes and may be secreted out, thereby increasing lactate in circulation. Lactate can potentially serve as a marker of RV dysfunction in PAH, which warrants investigation.

Exploring the impact of circRNAs on cancer glycolysis: Insights into tumor progression and therapeutic strategies

Cancer cells exhibit altered metabolic pathways, prominently featuring enhanced glycolytic activity to sustain their rapid growth and proliferation. Dysregulation of glycolysis is a well-established hallmark of cancer and contributes to tumor progression and resistance to therapy. Increased glycolysis supplies the energy necessary for increased proliferation and creates an acidic milieu, which in turn encourages tumor cells' infiltration, metastasis, and chemoresistance. Circular RNAs (circRNAs) have emerged as pivotal players in diverse biological processes, including cancer development and metabolic reprogramming. The interplay between circRNAs and glycolysis is explored, illuminating how circRNAs regulate key glycolysis-associated genes and enzymes, thereby influencing tumor metabolic profiles. In this overview, we highlight the mechanisms by which circRNAs regulate glycolytic enzymes and modulate glycolysis. In addition, we discuss the clinical implications of dysregulated circRNAs in cancer glycolysis, including their potential use as diagnostic and prognostic biomarkers. All in all, in this overview, we provide the most recent findings on how circRNAs operate at the molecular level to control glycolysis in various types of cancer, including hepatocellular carcinoma (HCC), prostate cancer (PCa), colorectal cancer (CRC), cervical cancer (CC), glioma, non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer (GC). In conclusion, this review provides a comprehensive overview of the significance of circRNAs in cancer glycolysis, shedding light on their intricate roles in tumor development and presenting innovative therapeutic avenues.

Phase separation of PML/RARα and BRD4 coassembled microspeckles governs transcriptional dysregulation in acute promyelocytic leukemia

In acute promyelocytic leukemia (APL), the promyelocytic leukemia-retinoic acid receptor alpha (PML/RARα) fusion protein destroys PML nuclear bodies (NBs), leading to the formation of microspeckles. However, our understanding, largely learned from morphological observations, lacks insight into the mechanisms behind PML/RARα-mediated microspeckle formation and its role in APL leukemogenesis. This study presents evidence uncovering liquid-liquid phase separation (LLPS) as a key mechanism in the formation of PML/RARα-mediated microspeckles. This process is facilitated by the intrinsically disordered region containing a large portion of PML and a smaller segment of RARα. We demonstrate the coassembly of bromodomain-containing protein 4 (BRD4) within PML/RARα-mediated condensates, differing from wild-type PML-formed NBs. In the absence of PML/RARα, PML NBs and BRD4 puncta exist as two independent phases, but the presence of PML/RARα disrupts PML NBs and redistributes PML and BRD4 into a distinct phase, forming PML/RARα-assembled microspeckles. Genome-wide profiling reveals a PML/RARα-induced BRD4 redistribution across the genome, with preferential binding to super-enhancers and broad-promoters (SEBPs). Mechanistically, BRD4 is recruited by PML/RARα into nuclear condensates, facilitating BRD4 chromatin binding to exert transcriptional activation essential for APL survival. Perturbing LLPS through chemical inhibition (1, 6-hexanediol) significantly reduces chromatin co-occupancy of PML/RARα and BRD4, attenuating their target gene activation. Finally, a series of experimental validations in primary APL patient samples confirm that PML/RARα forms microspeckles through condensates, recruits BRD4 to coassemble condensates, and co-occupies SEBP regions. Our findings elucidate the biophysical, pathological, and transcriptional dynamics of PML/RARα-assembled microspeckles, underscoring the importance of BRD4 in mediating transcriptional activation that enables PML/RARα to initiate APL.

Effect of elastin on abnormal proliferation of pulmonary artery smooth muscle cells at an early stage of hypoxic exposure

Elastin (Eln) is an extracellular matrix protein implicated in the proliferation of vascular smooth muscle cells. However, its potential role in hypoxic pulmonary hypertension (HPH) remains uncertain. This study is the first to demonstrate that elastin can promote the proliferation of mouse pulmonary artery smooth muscle cells (mPASMCs) and that hypoxia significantly induces Eln expression in cultured mPASMCs, thereby participating in the cell cycle. Interference with Eln expression via siRNA led to the downregulation of PCNA, Cyclin A, and Cyclin D, thus, the hypoxia-induced proliferation of mPASMCs was reversed. Furthermore, our study demonstrated that the hypoxia-induced expression of Eln and the proliferation of mPASMCs are associated with the proliferation-related phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. In conclusion, these data suggest that Eln is a key regulatory factor in mPASMCs proliferation, potentially elucidating the mechanism underlying hypoxia-induced mPASMCs proliferation. This finding may offer valuable insights for the study of hypoxic pulmonary hypertension.

Urolithin A Protects against Hypoxia-Induced Pulmonary Hypertension by Inhibiting Pulmonary Arterial Smooth Muscle Cell Pyroptosis via AMPK/NF-κB/NLRP3 Signaling

Recent studies confirmed that pyroptosis is involved in the progression of pulmonary hypertension (PH), which could promote pulmonary artery remodeling. Urolithin A (UA), an intestinal flora metabolite of ellagitannins (ETs) and ellagic acid (EA), has been proven to possess inhibitory effects on pyroptosis under various pathological conditions. However, its role on PH remained undetermined. To investigate the potential of UA in mitigating PH, mice were exposed to hypoxia (10% oxygen, 4 weeks) to induce PH, with or without UA treatment. Moreover, in vitro experiments were carried out to further uncover the underlying mechanisms. The in vivo treatment of UA suppressed the progression of PH via alleviating pulmonary remodeling. Pyroptosis-related genes were markedly upregulated in mice models of PH and reversed after the administration of UA. In accordance with that, UA treatment significantly inhibited hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) pyroptosis via the AMPK/NF-κB/NLRP3 pathway. Our results revealed that UA treatment effectively mitigated PH progression through inhibiting PASMC pyroptosis, which represents an innovative therapeutic approach for PH.

Exploring the pathogenesis of pulmonary vascular disease

Pulmonary hypertension (PH) is a complex cardiopulmonary disorder impacting the lung vasculature, resulting in increased pulmonary vascular resistance that leads to right ventricular dysfunction. Pulmonary hypertension comprises of 5 groups (PH group 1 to 5) where group 1 pulmonary arterial hypertension (PAH), results from alterations that directly affect the pulmonary arteries. Although PAH has a complex pathophysiology that is not completely understood, it is known to be a multifactorial disease that results from a combination of genetic, epigenetic and environmental factors, leading to a varied range of symptoms in PAH patients. PAH does not have a cure, its incidence and prevalence continue to increase every year, resulting in higher morbidity and mortality rates. In this review, we discuss the different pathologic mechanisms with a focus on epigenetic modifications and their roles in the development and progression of PAH. These modifications include DNA methylation, histone modifications, and microRNA dysregulation. Understanding these epigenetic modifications will improve our understanding of PAH and unveil novel therapeutic targets, thus steering research toward innovative treatment strategies.

TRPC4 aggravates hypoxic pulmonary hypertension by promoting pulmonary endothelial cell apoptosis

Pulmonary hypertension (PH) is a devastating disease that lacks effective treatment options and is characterized by severe pulmonary vascular remodeling. Pulmonary arterial endothelial cell (PAEC) dysfunction drives the initiation and pathogenesis of pulmonary arterial hypertension. Canonical transient receptor potential (TRPC) channels, a family of Ca2+-permeable channels, play an important role in various diseases. However, the effect and mechanism of TRPCs on PH development have not been fully elucidated. Among the TRPC family members, TRPC4 expression was markedly upregulated in PAECs from hypoxia combined with SU5416 (HySu)-induced PH mice and monocrotaline (MCT)-treated PH rats, as well as in hypoxia-exposed PAECs, suggesting that TRPC4 in PAECs may participate in the occurrence and development of PH. In this study, we aimed to investigate whether TRPC4 in PAECs has an aggravating effect on PH and elucidate the molecular mechanisms. We observed that hypoxia treatment promoted PAEC apoptosis through a caspase-12/endoplasmic reticulum stress (ERS)-dependent pathway. Knockdown of TRPC4 attenuated hypoxia-induced apoptosis and caspase-3/caspase-12 activity in PAECs. Accordingly, adeno-associated virus (AAV) serotype 6-mediated pulmonary endothelial TRPC4 silencing (AAV6-Tie-shRNA-TRPC4) or TRPC4 antagonist suppressed PH progression as evidenced by reduced right ventricular systolic pressure (RVSP), pulmonary vascular remodeling, PAEC apoptosis and reactive oxygen species (ROS) production. Mechanistically, unbiased RNA sequencing (RNA-seq) suggested that TRPC4 deficiency suppressed the expression of the proapoptotic protein sushi domain containing 2 (Susd2) in hypoxia-exposed mouse PAECs. Moreover, TRPC4 activated hypoxia-induced PAEC apoptosis by promoting Susd2 expression. Therefore, inhibiting TRPC4 ameliorated PAEC apoptosis and hypoxic PH in animals by repressing Susd2 signaling, which may serve as a therapeutic target for the management of PH.

Doxorubicin-based ENO1 targeted drug delivery strategy enhances therapeutic efficacy against colorectal cancer

Alpha-enolase (ENO1), a multifunctional protein with carcinogenic properties, has emerged as a promising cancer biomarker because of its differential expression in cancer and normal cells. On the basis of this characteristic, we designed a cell-targeting peptide that specifically targets ENO1 and connected it with the drug doxorubicin (DOX) by aldehyde-amine condensation. A surface plasmon resonance (SPR) assay showed that the affinity for ENO1 was stronger (KD = 2.5 µM) for the resulting cell-targeting drug, DOX-P, than for DOX. Moreover, DOX-P exhibited acid-responsive capabilities, enabling precise release at the tumor site under the guidance of the homing peptide and alleviating DOX-induced cardiotoxicity. An efficacy experiment confirmed that, the targeting ability of DOX-P toward ENO1 demonstrated superior antitumor activity against colorectal cancer than that of DOX, while reducing its toxicity to cardiomyocytes. Furthermore, in vivo metabolic distribution results indicated low accumulation of DOX-P in nontumor sites, further validating its targeting ability. These results showed that the ENO1-targeted DOX-P peptide has great potential for application in targeted drug-delivery systems for colorectal cancer therapy.

A peripheral system disease-Pulmonary hypertension

Pulmonary hypertension (PH) is a cardiovascular disorder characterized by substantial morbidity and mortality rates. It is a chronic condition characterized by intricate pathogenesis and uncontrollable factors. We summarized the pathological effects of estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification on PH. PH is not only a pulmonary vascular disease, but also a systemic disease. The findings emphasize that the onset of PH is not exclusively confined to the pulmonary vasculature, consequently necessitating treatment approaches that extend beyond targeting pulmonary blood vessels. Hence, the research on the pathological mechanism of PH is not limited to target organs such as pulmonary vessels, but also focuses on exploring other fields (such as estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification).

Elucidating VSMC phenotypic transition mechanisms to bridge insights into cardiovascular disease implications

Cardiovascular diseases (CVD) are the leading cause of death worldwide, despite advances in understanding cardiovascular health. Significant barriers still exist in effectively preventing and managing these diseases. Vascular smooth muscle cells (VSMCs) are crucial for maintaining vascular integrity and can switch between contractile and synthetic functions in response to stimuli such as hypoxia and inflammation. These transformations play a pivotal role in the progression of cardiovascular diseases, facilitating vascular modifications and disease advancement. This article synthesizes the current understanding of the mechanisms and signaling pathways regulating VSMC phenotypic transitions, highlighting their potential as therapeutic targets in cardiovascular disease interventions.

Neuron-Specific Enolase-What Are We Measuring?

Since the discovery of the neuron-specific protein by Moore and McGregor in 1965, tens of thousands of studies have investigated the basic and applied significance of neuron-specific enolase (NSE). This promising biomarker, according to many researchers, has not found widespread use in clinical practice, particularly in acute cerebrovascular accidents. Moreover, the several studies refuting the usefulness of serum NSE measurement in critically ill patients leads us to consider the reasons for such contradictory conclusions. In this article, we have analyzed the main directions in the study of NSE and expressed our perspective on the reasons for the contradictory results and the difficulties in implementing the results of these studies in clinical practice. In our opinion, the method of the enzyme-linked immunosorbent assay (ELISA) used in the majority of the studies is inappropriate for the evaluation of NSE as a marker of central nervous system damage, because it does not allow for the differentiation of heterodimers of enolases and the assessment of the enzymatic activity of this group of enzymatic proteins. Therefore, the methodological approach for the evaluation of NSE (γγ-enolase) as a biomarker needs to be elaborated and improved. Furthermore, the specificity of the applied research methods and the appropriateness of the continued use of the term "neuron-specific enolase" must be addressed.

Identification of the shared hub gene signatures and molecular mechanisms between HIV-1 and pulmonary arterial hypertension

The close link between HIV-1 infection and the occurrence of pulmonary arterial hypertension (PAH). However, the underlying molecular mechanisms of their interrelation remain unclear. The microarray data of HIV-1 and PAH were downloaded from GEO database. We utilized WGCNA to identify shared genes between HIV-1 and PAH, followed by conducting GO and pathway enrichment analyses. Subsequently, differentially genes analysis was performed using external validation datasets to further filter hub genes. Immunoinfiltration analysis was performed using CIBERSORT. Finally, hub gene expression was validated using scRNA-seq data. We identified 109 shared genes through WGCNA, primarily enriched in type I interferon (IFN) pathways. By taking the intersection of WGCNA important module genes and DEGs, ISG15 and IFI27 were identified as pivotal hub genes. Immunoinfiltration analysis and scRNA-seq results indicated the significant role of monocytes in the shared molecular mechanisms of HIV-1 and PAH. In summary, our study illustrated the possible mechanism of PAH secondary to HIV-1 and showed that the heightened IFN response in HIV-1 might be a crucial susceptibility factor for PAH, with monocytes being pivotal cells involved in the type I IFN response pathway. This provides potential new insights for further investigating the molecular mechanisms connecting HIV-1 and PAH.

Gamut of glycolytic enzymes in vascular smooth muscle cell proliferation: Implications for vascular proliferative diseases

Vascular smooth muscle cells (VSMCs) are the predominant cell type in the media of the blood vessels and are responsible for maintaining vascular tone. Emerging evidence confirms that VSMCs possess high plasticity. During vascular injury, VSMCs switch from a "contractile" phenotype to an extremely proliferative "synthetic" phenotype. The balance between both strongly affects the progression of vascular remodeling in many cardiovascular pathologies such as restenosis, atherosclerosis and aortic aneurism. Proliferating cells demand high energy requirements and to meet this necessity, alteration in cellular bioenergetics seems to be essential. Glycolysis, fatty acid metabolism, and amino acid metabolism act as a fuel for VSMC proliferation. Metabolic reprogramming of VSMCs is dynamically variable that involves multiple mechanisms and encompasses the coordination of various signaling molecules, proteins, and enzymes. Here, we systemically reviewed the metabolic changes together with the possible treatments that are still under investigation underlying VSMC plasticity which provides a promising direction for the treatment of diseases associated with VSMC proliferation. A better understanding of the interaction between metabolism with associated signaling may uncover additional targets for better therapeutic strategies in vascular disorders.

Single-cell RNA sequencing unveils unique transcriptomic signatures of endothelial cells and role of ENO1 in response to disturbed flow

Flow patterns exert significant effects on vascular endothelial cells (ECs) to lead to the focal nature of atherosclerosis. Using a step flow chamber to investigate the effects of disturbed shear (DS) and pulsatile shear (PS) on ECs in the same flow channel, we conducted single-cell RNA sequencing analyses to explore the distinct transcriptomic profiles regulated by DS vs. PS. Integrated analysis identified eight cell clusters and demonstrated that DS induces EC transition from atheroprotective to proatherogenic phenotypes. Using an automated cell type annotation algorithm (SingleR), we showed that DS promoted endothelial-to-mesenchymal transition (EndMT) by inducing the transcriptional phenotypes for inflammation, hypoxia responses, transforming growth factor-beta (TGF-β) signaling, glycolysis, and fatty acid synthesis. Enolase 1 (ENO1), a key gene in glycolysis, was one of the top-ranked genes in the DS-induced EndMT cluster. Pseudotime trajectory analysis revealed that the kinetic expression of ENO1 was significantly associated with EndMT and that ENO1 silencing repressed the DS- and TGF-β-induced EC inflammation and EndMT. Consistent with these findings, ENO1 was highly expressed in ECs at the inner curvature of the mouse aortic arch (which is exposed to DS) and atherosclerotic lesions, suggesting its proatherogenic role in vivo. In summary, we present a comprehensive single-cell atlas of ECs in response to different flow patterns within the same flow channel. Among the DS-regulated genes, ENO1 plays an important role in DS-induced EC inflammation and EndMT. These results provide insights into how hemodynamic forces regulate vascular endothelium in health and disease.

The role and mechanism of AMPK in pulmonary hypertension

Pulmonary hypertension (PH) is a chronic progressive disease with high mortality. There has been more and more research focusing on the role of AMPK in PH. AMPK consists of three subunits-α, β, and γ. The crosstalk among these subunits ultimately leads to a delicate balance to affect PH, which results in conflicting conclusions about the role of AMPK in PH. It is still unclear how these subunits interfere with each other and achieve balance to improve or deteriorate PH. Several signaling pathways are related to AMPK in the treatment of PH, including AMPK/eNOS/NO pathway, Nox4/mTORC2/AMPK pathway, AMPK/BMP/Smad pathway, and SIRT3-AMPK pathway. Among these pathways, the role and mechanism of AMPK/eNOS/NO and Nox4/mTORC2/AMPK pathways are clearer than others, while the SIRT3-AMPK pathway remains still unclear in the treatment of PH. There are drugs targeting AMPK to improve PH, such as metformin (MET), MET combination, and rhodiola extract. In addition, several novel factors target AMPK for improving PH, such as ADAMTS8, TUFM, and Salt-inducible kinases. However, more researches are needed to explore the specific AMPK signaling pathways involved in these novel factors in the future. In conclusion, AMPK plays an important role in PH.

Canagliflozin ameliorates hypobaric hypoxia-induced pulmonary arterial hypertension by inhibiting pulmonary arterial smooth muscle cell proliferation

Pulmonary arterial hypertension (PAH) is a disease with a high mortality and few treatment options to prevent the development of pulmonary vessel remodeling, pulmonary vascular resistance, and right ventricular failure. Canagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is originally used in diabetes patients which could assist the glucose excretion and decrease blood glucose. Recently, a few studies have reported the protective effect of SGLT2 inhibitor on monocrotaline-induced PAH. However, the effects of canagliflozin on hypobaric hypoxia-induced PAH as well as its mechanism still unclear. In this study, we used hypobaric hypoxia-induced PAH mice model to demonstrate if canagliflozin could alleviate PAH and prevent pulmonary vessel remodeling. We found that daily canagliflozin administration significantly improved survival in mice with hypobaric hypoxia-induced PAH compared to vehicle control. Canagliflozin treatment significantly reduced right ventricular systolic pressure and increased pulmonary acceleration time determined by hemodynamic assessments. Canagliflozin significantly reduced medial wall thickening and decreased muscularization of pulmonary arterioles compared to vehicle treated mice. In addition, canagliflozin inhibited the proliferation and migration of pulmonary arterial smooth muscle cells through suppressing glycolysis and reactivating AMP-activated protein kinase signaling pathway under hypoxia condition. In summary, our findings suggest that canagliflozin is sufficient to inhibit pulmonary arterial remodeling which is a potential therapeutic strategy for PAH treatment.

Study of Transcriptomic Analysis of Yak (Bos grunniens) and Cattle (Bos taurus) Pulmonary Artery Smooth Muscle Cells under Oxygen Concentration Gradients and Differences in Their Lung Histology and Expression of Pyruvate Dehydrogenase Kinase 1-Related Factors

The aim of this study was to investigate the molecular mechanisms by which hypoxia affects the biological behavior of yak PASMCs, the changes in the histological structure of yak and cattle lungs, and the relationships and regulatory roles that exist regarding the differences in the distribution and expression of PDK1 and its hypoxia-associated factors screened for their role in the adaptation of yak lungs to the plateau hypoxic environment. The results showed that, at the level of transcriptome sequencing, the molecular regulatory mechanisms of the HIF-1 signaling pathway, glucose metabolism pathway, and related factors (HK2/PGK1/ENO1/ENO3/ALDOC/ALDOA) may be closely related to the adaptation of yaks to the hypoxic environment of the plateau; at the tissue level, the presence of filled alveoli and semi-filled alveoli, thicker alveolar septa and basement membranes, a large number of erythrocytes, capillary distribution, and collagen fibers accounted for all levels of fine bronchioles in the lungs of yaks as compared to cattle. A higher percentage of goblet cells was found in the fine bronchioles of yaks, and PDK1, HIF-1α, and VEGF were predominantly distributed and expressed in the monolayers of ciliated columnar epithelium in the branches of the terminal fine bronchioles of yak and cattle lungs, with a small amount of it distributed in the alveolar septa; at the molecular level, the differences in PDK1 mRNA relative expression in the lungs of adult yaks and cattle were not significant (p > 0.05), the differences in HIF-1α and VEGF mRNA relative expression were significant (p < 0.05), and the expression of PDK1 and HIF-1α proteins in adult yaks was stronger than that in adult cattle. PDK1 and HIF-1α proteins were more strongly expressed in adult yaks than in adult cattle, and the difference was highly significant (p < 0.01); the relative expression of VEGF proteins was not significantly different between adult yaks and cattle (p > 0.05). The possible regulatory relationship between the above results and the adaptation of yak lungs to the plateau hypoxic environment paves the way for the regulatory mechanisms of PDK1, HIF-1α, and VEGF, and provides basic information for studying the mechanism of hypoxic adaptation of yaks in the plateau. At the same time, it provides a reference for human hypoxia adaptation and a target for the prevention and treatment of plateau diseases in humans and plateau animals.

4-Terpineol attenuates pulmonary vascular remodeling via suppressing PI3K/Akt signaling pathway in hypoxia-induced pulmonary hypertension rats

The hyperproliferation of pulmonary arterial smooth muscle cells (PASMCs) plays a pivotal role in pulmonary arterial remodeling (PAR) of hypoxia-induced pulmonary hypertension (HPH). 4-Terpineol is a constituent of Myristic fragrant volatile oil in Santan Sumtang. Our previous study found that Myristic fragrant volatile oil alleviated PAR in HPH rats. However, the effect and pharmacological mechanism of 4-terpineol in HPH rats remain unexplored. Male Sprague-Dawley rats were exposed to hypobaric hypoxia chamber (simulated altitudes of 4500 m) for 4 weeks to establish an HPH model in this study. During this period, rats were intragastrically administrated with 4-terpineol or sildenafil. After that, hemodynamic indexes and histopathological changes were assessed. Moreover, a hypoxia-induced cellular proliferative model was established by exposing PASMCs to 3% O2. PASMCs were pretreated with 4-terpineol or LY294002 to explore whether 4-terpineol targeted PI3K/Akt signaling pathway. The PI3K/Akt-related proteins expression was also accessed in lung tissues of HPH rats. We found that 4-terpineol attenuated mPAP and PAR in HPH rats. Then, cellular experiments showed 4-terpineol inhibited hypoxia-induced PASMCs proliferation via down-regulating PI3K/Akt expression. Furthermore, 4-terpineol decreased the p-Akt, p-p38, and p-GSK-3β protein expression, as well as reduced the PCNA, CDK4, Bcl-2 and Cyclin D1 protein levels, while increasing levels of cleaved caspase 3, Bax, and p27kip1in lung tissues of HPH rats. Our results suggested that 4-terpineol mitigated PAR in HPH rats by inhibiting the proliferation and inducing apoptosis of PASMCs through suppression of the PI3K/Akt-related signaling pathway.

Evidence for Hypoxia-Induced Shift in ATP Production from Glycolysis to Mitochondrial Respiration in Pulmonary Artery Smooth Muscle Cells in Pulmonary Arterial Hypertension

BACKGROUND

The metabolic state of pulmonary artery smooth muscle cells (PASMCs) from patients with pulmonary arterial hypertension (PAH) is not well understood. In this study, we examined the balance between glycolysis and mitochondrial respiration in non-PAH-PASMCs and PAH-PASMCs under normoxia and hypoxia.

METHODS

We investigated the enzymes involved in glycolysis and mitochondrial respiration, and studied the two major energy-yielding pathways (glycolysis and mitochondrial respiration) by measuring extracellular acidification rate (ECAR) and cellular oxygen consumption rate (OCR) using the Seahorse extracellular flux technology.

RESULTS

Under both normoxia and hypoxia, the mRNA and protein levels of pyruvate dehydrogenase kinase 1 and pyruvate dehydrogenase were increased in PAH-PASMCs compared with non-PAH-PASMCs. The mRNA and protein levels of lactate dehydrogenase, as well as the intracellular lactate concentration, were also increased in PAH-PASMCs compared with non-PAH-PASMCs under normoxia. However, these were not significantly increased in PAH-PASMCs compared with non-PAH-PASMCs under hypoxia. Under normoxia, ATP production was significantly lower in PAH-PASMCs (59 ± 5 pmol/min) than in non-PAH-PASMCs (70 ± 10 pmol/min). On the other hand, ATP production was significantly higher in PAH-PASMCs (31 ± 5 pmol/min) than in non-PAH-PASMCs (14 ± 3 pmol/min) under hypoxia.

CONCLUSIONS

There is an underlying change in the metabolic strategy to generate ATP production under the challenge of hypoxia.

Identification of potential ferroptosis-associated biomarkers in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by inflammation and gradual joint degeneration, resulting in function disability. Recently, ferroptosis, a novel form of regulated cell death that involves iron-dependent lipid peroxidation, has been implicated in the pathogenesis of RA. However, the underlying molecular mechanisms and key genes involved in ferroptosis in RA remain largely unknown.

Methods

The GSE134420 and GSE77298 datasets were downloaded and DEGs were identified using R software. The DEGs were then mapped to the dataset of 619 ferroptosis-related genes obtained from the GeneCards database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were conducted to investigate the possible biological functions. Protein-protein interaction (PPI) networks were constructed to identify the hub genes. The relationship between hub genes and immune infiltration was estimated using the CIBERSORT algorithms. Gene Set Enrichment Analysis (GSEA) was used to explore the underlying signaling pathways of hub genes. Genome-wide association studies (GWAS) analysis was performed to confirm the pathogenic regions of the hub genes. RcisTarget and Gene-motif ranking databases were used to identify transcription factors (TFs) associated with the hub genes. The miRcode databases were utilized to construct the microRNA (miRNA)-messenger RNA (mRNA) network. Single-cell analysis was utilized to cluster cells and display the expression of hub genes in cell clusters. Finally, the expression and potential mechanism of hub genes were investigated in human and experimental samples.

Results

Three hub genes PTGS2, ENO1, and GRN highly associated with ferroptosis were identified. Four pathogenic genes HLA-B, MIF, PSTPIP, TLR1 were identified that were significantly and positively correlated with the expression levels of hub genes. The results of the GSEA showed that the hub genes were significantly enriched in pathways related to immunity, lysosome, phagocytosis and infection. ENO1 and PTGS2 were enriched in the TF-binding motif of cisbp_M5493. The hub genes were validated in experimental and patient samples and highly level of ENO1 expression was found to inhibit ACO1, which reduces ferroptosis in proliferating fibroblast-like synoviocytes (FLS).

Conclusion

PTGS2, ENO1 and GRN were identified and validated as potential ferroptosis-related biomarkers. Our work first revealed that ENO1 is highly expressed in RA synovium and that ferroptosis may be regulated by the ENO1-ACO1 axis, advancing the understanding of the underlying ferroptosis-related mechanisms of synovial proliferation and providing potential diagnostic and therapeutic targets for RA.

Circular RNAs in hepatocellular carcinoma: biogenesis, function, and pathology

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Both genetic and environmental factors through a multitude of underlying molecular mechanisms participate in the pathogenesis of HCC. Recently, numerous studies have shown that circular RNAs (circRNAs), an emerging class of non-coding RNAs characterized by the presence of covalent bonds linking 3' and 5' ends, play an important role in the initiation and progression of cancers, including HCC. In this review, we outline the current status of the field of circRNAs, with an emphasis on the functions and mechanisms of circRNAs in HCC and its microenvironment. We also summarize and discuss recent advances of circRNAs as biomarkers and therapeutic targets. These efforts are anticipated to throw new insights into future perspectives about circRNAs in basic, translational and clinical research, eventually advancing the diagnosis, prevention and treatment of HCC.

Current understanding of the contribution of lactate to the cardiovascular system and its therapeutic relevance

Research during the past decades has yielded numerous insights into the presence and function of lactate in the body. Lactate is primarily produced via glycolysis and plays special roles in the regulation of tissues and organs, particularly in the cardiovascular system. In addition to being a net consumer of lactate, the heart is also the organ in the body with the greatest lactate consumption. Furthermore, lactate maintains cardiovascular homeostasis through energy supply and signal regulation under physiological conditions. Lactate also affects the occurrence, development, and prognosis of various cardiovascular diseases. We will highlight how lactate regulates the cardiovascular system under physiological and pathological conditions based on evidence from recent studies. We aim to provide a better understanding of the relationship between lactate and cardiovascular health and provide new ideas for preventing and treating cardiovascular diseases. Additionally, we will summarize current developments in treatments targeting lactate metabolism, transport, and signaling, including their role in cardiovascular diseases.

Targeting Mitochondrial Metabolic Dysfunction in Pulmonary Hypertension: Toward New Therapeutic Approaches?

Pulmonary arterial hypertension (PAH) is a rare disease characterized by pulmonary vascular remodeling leading to right heart failure and death. To date, despite the three therapeutic approaches targeting the three major endothelial dysfunction pathways based on the prostacyclin, nitric oxide/cyclic guanosine monophosphate, and endothelin pathways, PAH remains a serious disease. As such, new targets and therapeutic agents are needed. Mitochondrial metabolic dysfunction is one of the mechanisms involved in PAH pathogenesis in part through the induction of a Warburg metabolic state of enhanced glycolysis but also through the upregulation of glutaminolysis, tricarboxylic cycle and electron transport chain dysfunction, dysregulation of fatty acid oxidation or mitochondrial dynamics alterations. The aim of this review is to shed light on the main mitochondrial metabolic pathways involved in PAH and to provide an update on the resulting interesting potential therapeutic perspectives.

Exosomal miR-663b from "M1" macrophages promotes pulmonary artery vascular smooth muscle cell dysfunction through inhibiting the AMPK/Sirt1 axis

BACKGROUND

Inflammatory mediators from macrophages are proven to be involved in pulmonary vascular remodeling in pulmonary hypertension (PH). Here, this study intends to explore the mechanism of "M1" macrophage-derived exosomal miR-663b in pulmonary artery smooth muscle cells (PASMCs) dysfunctions and pulmonary hypertension.

METHODS

Hypoxia-treated PASMCs were utilized for constructing an in-vitro pulmonary hypertension model. THP-1 cells were treated with PMA (320 nM) and LPS (10 μg/mL) + IFN-γ (20 ng/ml) for eliciting macrophage "M1" polarization. Exosomes derived from "M1" macrophages were isolated and added into PASMCs. The proliferation, inflammation, oxidative stress, and migration of PASMCs were evaluated. RT-PCR or Western blot examined the levels of miR-663b and the AMPK/Sirt1 pathway. Dual luciferase activity assay and RNA pull-down assay were carried out for confirming the targeted association between miR-663b and AMPK. An in-vivo PH model was built. Macrophage-derived exosomes with miR-663b inhibition were used for treating the rats, and alterations of pulmonary histopathology were monitored.

RESULTS

miR-663b was obviously up-regulated in hypoxia-elicited PASMCs and M1 macrophages. miR-663b overexpression boosted hypoxia-induced proliferation, inflammation, oxidative stress, and migration in PASMCs, whereas miR-663b low expression resulted in the opposite situation. AMPK was identified as a target of miR-663b, and miR-663b overexpression curbed the AMPK/Sirt1 pathway. AMPK activation ameliorated the damaging impact of miR-663b overexpression and "M1" macrophage exosomes on PASMCs. In vivo, "M1" macrophage exosomes with miR-663b low expression alleviated pulmonary vascular remodeling in pulmonary hypertension rats.

CONCLUSION

Exosomal miR-663b from "M1" macrophage facilitates PASMC dysfunctions and PH development by dampening the AMPK/Sirt1 axis.

Kaempferol ameliorates pulmonary vascular remodeling in chronic hypoxia-induced pulmonary hypertension rats via regulating Akt-GSK3β-cyclin axis

Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) is considered a major contributor to elevated pulmonary vascular resistance and a key mechanism of vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Kaempferol is a natural flavonoid compound and can be derived from numerous common medicinal herbs and vegetables, which exhibit antiproliferative and proapoptotic properties, however, the effects of kaempferol on vascular remodeling in HPH remain unexplored. In this study, SD rats were placed in a hypobaric hypoxia chamber for four weeks to establish a pulmonary hypertension model and given either kaempferol or sildenafil (an inhibitor of PDE-5) during days 1-28, after which the hemodynamic parameter and pulmonary vascular morphometry were assessed. Furthermore, primary rat PASMCs were exposed to hypoxic conditions to generate a cell proliferation model, then incubated with either kaempferol or LY294002 (an inhibitor of PI3K). Immunoblotting and real-time quantitative PCR assessed the protein and mRNA expression levels in HPH rat lungs and PASMCs. We found that kaempferol reduced pulmonary artery pressure and pulmonary vascular remodeling, and alleviated right ventricular hypertrophy in HPH rats. The mechanistic analysis demonstrated that kaempferol reduced the protein levels of phosphorylation of Akt and GSK3β, leading to decreased expression of pro-proliferation (CDK2, CDK4, Cyclin D1, and PCNA) and anti-apoptotic related proteins (Bcl-2) and increased expression of pro-apoptosis proteins (Bax and cleaved caspase 3). These results collectively demonstrate that kaempferol ameliorates HPH in rats by inhibiting PASMC proliferation and pro-apoptosis via modulation of the Akt/GSK3β/CyclinD axis.

Non-metabolic role of alpha-enolase in virus replication

Viruses are extremely complex and highly evolving microorganisms; thus, it is difficult to analyse them in detail. The virion is believed to contain all the essential components required from its entry to the establishment of a successful infection in a susceptible host cell. Hence, the virion composition is the principal source for its transmissibility and immunogenicity. A virus is completely dependent on a host cell for its replication and progeny production. Occasionally, they recruit and package host proteins into mature virion. These incorporated host proteins are believed to play crucial roles in the subsequent infection, although the significance and the molecular mechanism regulated are poorly understood. One such host protein which is hijacked by several viruses is the glycolytic enzyme, Enolase (Eno-1) and is also packaged into mature virion of several viruses. This enzyme exhibits a highly flexible nature of functions, ranging from metabolic to several non-metabolic activities. All the glycolytic enzymes are known to be moonlighting proteins including enolase. The non-metabolic functions of this moonlighting protein are also highly diverse with respect to its cellular localization. Although very little is known about the virological significance of this enzyme, several of its non-metabolic functions have been observed to influence the virus replication cycle in infected cells. In this review, we have attempted to provide a comprehensive picture of the non-metabolic role of Eno-1, its significance in the virus replication cycle and to stimulate interest around its scope as a therapeutic target for treating viral pathologies.

Pathophysiology and new advances in pulmonary hypertension

Pulmonary hypertension is a progressive and often fatal cardiopulmonary condition characterised by increased pulmonary arterial pressure, structural changes in the pulmonary circulation, and the formation of vaso-occlusive lesions. These changes lead to increased right ventricular afterload, which often progresses to maladaptive right ventricular remodelling and eventually death. Pulmonary arterial hypertension represents one of the most severe and best studied types of pulmonary hypertension and is consistently targeted by drug treatments. The underlying molecular pathogenesis of pulmonary hypertension is a complex and multifactorial process, but can be characterised by several hallmarks: inflammation, impaired angiogenesis, metabolic alterations, genetic or epigenetic abnormalities, influence of sex and sex hormones, and abnormalities in the right ventricle. Current treatments for pulmonary arterial hypertension and some other types of pulmonary hypertension target pathways involved in the control of pulmonary vascular tone and proliferation; however, these treatments have limited efficacy on patient outcomes. This review describes key features of pulmonary hypertension, discusses current and emerging therapeutic interventions, and points to future directions for research and patient care. Because most progress in the specialty has been made in pulmonary arterial hypertension, this review focuses on this type of pulmonary hypertension. The review highlights key pathophysiological concepts and emerging therapeutic directions, targeting inflammation, cellular metabolism, genetics and epigenetics, sex hormone signalling, bone morphogenetic protein signalling, and inhibition of tyrosine kinase receptors.

Mitochondrial dysfunction in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by the increased pulmonary vascular resistance due to pulmonary vasoconstriction and vascular remodeling. PAH has high disability, high mortality and poor prognosis, which is becoming a more common global health issue. There is currently no drug that can permanently cure PAH patients. The pathogenesis of PAH is still not fully elucidated. However, the role of metabolic theory in the pathogenesis of PAH is becoming clearer, especially mitochondrial metabolism. With the deepening of mitochondrial researches in recent years, more and more studies have shown that the occurrence and development of PAH are closely related to mitochondrial dysfunction, including the tricarboxylic acid cycle, redox homeostasis, enhanced glycolysis, and increased reactive oxygen species production, calcium dysregulation, mitophagy, etc. This review will further elucidate the relationship between mitochondrial metabolism and pulmonary vasoconstriction and pulmonary vascular remodeling. It might be possible to explore more comprehensive and specific treatment strategies for PAH by understanding these mitochondrial metabolic mechanisms.

Oncometabolism: A Paradigm for the Metabolic Remodeling of the Failing Heart

Heart failure is associated with profound alterations in cardiac intermediary metabolism. One of the prevailing hypotheses is that metabolic remodeling leads to a mismatch between cardiac energy (ATP) production and demand, thereby impairing cardiac function. However, even after decades of research, the relevance of metabolic remodeling in the pathogenesis of heart failure has remained elusive. Here we propose that cardiac metabolic remodeling should be looked upon from more perspectives than the mere production of ATP needed for cardiac contraction and relaxation. Recently, advances in cancer research have revealed that the metabolic rewiring of cancer cells, often coined as oncometabolism, directly impacts cellular phenotype and function. Accordingly, it is well feasible that the rewiring of cardiac cellular metabolism during the development of heart failure serves similar functions. In this review, we reflect on the influence of principal metabolic pathways on cellular phenotype as originally described in cancer cells and discuss their potential relevance for cardiac pathogenesis. We discuss current knowledge of metabolism-driven phenotypical alterations in the different cell types of the heart and evaluate their impact on cardiac pathogenesis and therapy.

Pyrroloquinoline quinone (PQQ) improves pulmonary hypertension by regulating mitochondrial and metabolic functions

Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and endothelial cells (PAECs), inflammation, as well as mitochondrial and metabolic dysregulation, contributes to the development of pulmonary hypertension (PH). Pyrroloquinoline quinone (PQQ), a potent natural antioxidant with anti-diabetic, neuroprotective, and cardioprotective properties, is known to promote mitochondrial biogenesis. However, its effect on cellular proliferation, apoptosis resistance, mitochondrial and metabolic alterations associated with PH remains unexplored. The current study was designed to investigate the effect of PQQ in the treatment of PH. Human pulmonary artery smooth muscle cells (HPASMCs), endothelial cells (PAECs), and primary cultured cardiomyocytes were subjected to hypoxia to induce PH-like phenotype. Furthermore, Sprague Dawley (SD) rats injected with monocrotaline (MCT) (60 mg/kg, SC, once) progressively developed pulmonary hypertension. PQQ treatment (2 mg/kg, PO, for 35 days) attenuated cellular proliferation and promoted apoptosis via a mitochondrial-dependent pathway. Furthermore, PQQ treatment in HPASMCs prevented mitochondrial and metabolic dysfunctions, improved mitochondrial bioenergetics while preserving respiratory complexes, and reduced insulin resistance. In addition, PQQ treatment (preventive and curative) significantly attenuated the increase in right ventricle pressure and hypertrophy as well as reduced endothelial dysfunction and pulmonary artery remodeling in MCT-treated rats. PQQ also prevented cardiac fibrosis and improved cardiac functions as well as reduced inflammation in MCT-treated rats. Altogether, the above findings demonstrate that PQQ can attenuate mitochondrial as well as metabolic abnormalities in PASMCs and also prevent the development of PH in MCT treated rats; hence PQQ may act as a potential therapeutic agent for the treatment of PH.

α-Enolase reduces cerebrovascular Aβ deposits by protecting Aβ amyloid formation

Cerebral amyloid angiopathy (CAA) is characterized by cerebrovascular amyloid β (Aβ) deposits and causes dementia and cerebral hemorrhage. Although α-enolase (ENO1) was shown to possess multifunctional roles, its exact functions in CAA pathogenesis have not been determined. In this study, we focused on ENO1, a well-known glycolytic enzyme, which was previously identified via a proteomic approach as an upregulated protein in brain samples from patients with Alzheimer's disease (AD). We utilized the thioflavin T fluorescence assay and transmission electron microscopy to monitor the effects of ENO1 on amyloid formation by Aβ peptides. We also cultured murine primary cerebrovascular smooth muscle cells to determine the effects of ENO1 on Aβ cytotoxicity. To investigate the effects of ENO1 in vivo, we infused ENO1 or a vehicle control into the brains of APP23 mice, a transgenic model of AD/CAA, using a continuous infusion system, followed by a cognitive test and pathological and biochemical analyses. We found that novel functions of ENO1 included interacting with Aβ and inhibiting its fibril formation, disrupting Aβ fibrils, and weakening the cytotoxic effects of these fibrils via proteolytic degradation of Aβ peptide. We also demonstrated that infusion of ENO1 into APP23 mouse brains reduced cerebrovascular Aβ deposits and improved cognitive impairment. In addition, we found that enzymatically inactivated ENO1 failed to inhibit Aβ fibril formation and fibril disruption. The proteolytic activity of ENO1 may thus underlie the enzyme's cytoprotective effect and clearance of Aβ from the brain, and ENO1 may be a therapeutic target in CAA.

FUNDC1-mediated mitophagy and HIF1α activation drives pulmonary hypertension during hypoxia

Hypoxic pulmonary hypertension (PH) is a progressive disease characterized by hyper-proliferation of pulmonary vascular cells including pulmonary artery smooth muscle cells (PASMCs) and can lead to right heart failure and early death. Selective degradation of mitochondria by mitophagy during hypoxia regulates mitochondrial functions in many cells, however, it is not clear if mitophagy is involved in the pathogenesis of hypoxic PH. By employing the hypoxic mitophagy receptor Fundc1 knockout (KO) and transgenic (TG) mouse models, combined hypoxic PH models, the current study found that mitophagy is actively involved in hypoxic PH through regulating PASMC proliferation. In the pulmonary artery medium from hypoxic PH mice, mitophagy was upregulated, accompanied with the increased active form of FUNDC1 protein and the enhanced binding affinity of FUNDC1 with LC3B. In PASMCs, overexpression of FUNDC1 increased mitophagy and cell proliferation while knockdown of FUNDC1 inhibited hypoxia-induced mitophagy and PASMC proliferation. Stimulation of mitophagy by FUNDC1 in PASMCs elevated ROS production and inhibited ubiquitination of hypoxia inducible factor 1α (HIF1α), and inhibition of mitophagy by FUNDC1 knockdown or knockout abolished hypoxia-induced ROS-HIF1α upregulation. Moreover, Fundc1 TG mice developed severe hemodynamics changes and pulmonary vascular remodeling, and Fundc1 KO mice were much resistant to hypoxic PH. In addition, intraperitoneal injection of a specific FUNDC1 peptide inhibitor to block mitophagy ameliorated hypoxic PH. Our results reveal that during hypoxic PH, FUNDC1-mediated mitophagy is upregulated which activates ROS-HIF1α pathway and promotes PASMC proliferation, ultimately leads to pulmonary vascular remodeling and PH.

Akt-Dependent Glycolysis-Driven Lipogenesis Supports Proliferation and Survival of Human Pulmonary Arterial Smooth Muscle Cells in Pulmonary Hypertension

Hyper-proliferation of pulmonary arterial vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). Lipogenesis is linked to numerous proliferative diseases, but its role in PAVSMC proliferation in PAH remains to be elucidated. We found that early-passage human PAH PAVSMC had significant up-regulation of key fatty acids synthesis enzymes ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FASN), and increased unstimulated proliferation compared to control human PAVSMC. Treatment with an allosteric ACC inhibitor 5-tetradecyloxy-2-furoic acid (TOFA) significantly decreased proliferation and induced apoptosis of human PAH PAVSMC. Intracellular lipid content and proliferation of PAH PAVSMC were not reduced by incubation in lipid-depleted media but suppressed by a non-metabolizable analog of glucose 2-Deoxy-D-glucose (2-DG) and partially restored by addition of pyruvate. Protein kinase Akt was upregulated in human PAH PAVSMC in a sirtuin 7 (SIRT7)- and c-Jun N-terminal kinase (JNK)-dependent manner. Pharmacological inhibition of Akt down-regulated ACLY and ACC, significantly reduced intracellular lipid content, inhibited proliferation and induced apoptosis of human PAH PAVSMC. Taken together, these data demonstrate that human PAH PAVSMC have up-regulated lipogenesis, which is supported in an Akt- and glycolysis-dependent manner and is required for increased proliferation and survival. Our data suggest that there is a mechanistic link between glycolysis, lipogenesis, and the proliferation of human PAH PAVSMC and call for further studies to determine the potential attractiveness of a SIRT7/JNK-Akt-lipogenesis axis as a target pathway to inhibit PAVSMC hyper-proliferation in PAH.

CCDC65, a Gene Knockout that leads to Early Death of Mice, acts as a potentially Novel Tumor Suppressor in Lung Adenocarcinoma

CCDC65 is a member of the coiled-coil domain-containing protein family and was only reported in gastric cancer by our group. We first observed that it is downregulated in lung adenocarcinoma based on the TCGA database. Reduced CCDC65 protein was shown as an unfavorable factor promoting the clinical progression in lung adenocarcinoma. Subsequently, CCDC65^-/- mice were found possibly dead of hydrocephalus. Compared with the CCDC65^+/+ mice, the downregulation of CCDC65 in CCDC65^+/- mice significantly increased the formation ability of lung cancer induced by urethane. In the subsequent investigation, we observed that CCDC65 functions as a tumor suppressor repressing cell proliferation in vitro and in vivo. Molecular mechanism showed that CCDC65 recruited E3 ubiquitin ligase FBXW7 to induce the ubiquitination degradation of c-Myc, an oncogenic transcription factor in tumors, and reduced c-Myc binding to ENO1 promoter, which suppressed the transcription of ENO1. In addition, CCDC65 also recruited FBXW7 to degrade ENO1 protein by ubiquitinated modulation. The downregulated ENO1 further reduced the phosphorylation activation of AKT1, which thus inactivated the cell cycle signal. Our data demonstrated that CCDC65 is a potential tumor suppressor by recruiting FBWX7 to suppress c-Myc/ENO1-induced cell cycle signal in lung adenocarcinoma.

Modulation of Pulmonary Toxicity in Metabolic Syndrome Due to Variations in Iron Oxide Nanoparticle-Biocorona Composition

Nanoparticles (NPs) interact with biomolecules by forming a biocorona (BC) on their surface after introduction into the body and alter cell interactions and toxicity. Metabolic syndrome (MetS) is a prevalent condition and enhances susceptibility to inhaled exposures. We hypothesize that distinct NP-biomolecule interactions occur in the lungs due to MetS resulting in the formation of unique NP-BCs contributing to enhanced toxicity. Bronchoalveolar lavage fluid (BALF) was collected from healthy and MetS mouse models and used to evaluate variations in the BC formation on 20 nm iron oxide (Fe₃O₄) NPs. Fe₃O₄ NPs without or with BCs were characterized for hydrodynamic size and zeta potential. Unique and differentially associated proteins and lipids with the Fe₃O₄ NPs were identified through proteomic and lipidomic analyses to evaluate BC alterations based on disease state. A mouse macrophage cell line was utilized to examine alterations in cell interactions and toxicity due to BCs. Exposures to 6.25, 12.5, 25, and 50 μg/mL of Fe₃O₄ NPs with BCs for 1 h or 24 h did not demonstrate overt cytotoxicity. Macrophages increasingly associated Fe₃O₄ NPs following addition of the MetS BC compared to the healthy BC. Macrophages exposed to Fe₃O₄ NPs with a MetS-BC for 1 h or 24 h at a concentration of 25 μg/mL demonstrated enhanced gene expression of inflammatory markers: CCL2, IL-6, and TNF-α compared to Fe₃O₄ NPs with a healthy BC. Western blot analysis revealed activation of STAT3, NF-κB, and ERK pathways due to the MetS-BC. Specifically, the Jak/Stat pathway was the most upregulated inflammatory pathway following exposure to NPs with a MetS BC. Overall, our study suggests the formation of distinct BCs due to NP exposure in MetS, which may contribute to exacerbated inflammatory effects and susceptibility.

AMPK and the Challenge of Treating Hypoxic Pulmonary Hypertension

Hypoxic pulmonary hypertension (HPH) is characterized by sustained elevation of pulmonary artery pressure produced by vasoconstriction and hyperproliferative remodeling of the pulmonary artery and subsequent right ventricular hypertrophy (RVH). The search for therapeutic targets for cardiovascular pathophysiology has extended in many directions. However, studies focused on mitigating high-altitude pulmonary hypertension (HAPH) have been rare. Because AMP-activated protein kinase (AMPK) is involved in cardiovascular and metabolic pathology, AMPK is often studied as a potential therapeutic target. AMPK is best characterized as a sensor of cellular energy that can also restore cellular metabolic homeostasis. However, AMPK has been implicated in other pathways with vasculoprotective effects. Notably, cellular metabolic stress increases the intracellular ADP/ATP or AMP/ATP ratio, and AMPK activation restores ATP levels by activating energy-producing catabolic pathways and inhibiting energy-consuming anabolic pathways, such as cell growth and proliferation pathways, promoting cardiovascular protection. Thus, AMPK activation plays an important role in antiproliferative, antihypertrophic and antioxidant pathways in the pulmonary artery in HPH. However, AMPK plays contradictory roles in promoting HPH development. This review describes the main findings related to AMPK participation in HPH and its potential as a therapeutic target. It also extrapolates known AMPK functions to discuss the less-studied HAPH context.

Integrated Bioinformatic Analysis Reveals TXNRD1 as a Novel Biomarker and Potential Therapeutic Target in Idiopathic Pulmonary Arterial Hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening cardiopulmonary disease lacking specific diagnostic markers and targeted therapy, and its mechanism of development remains to be elucidated. The present study aimed to explore novel diagnostic biomarkers and therapeutic targets in IPAH by integrated bioinformatics analysis. Four eligible datasets (GSE117261, GSE15197, GSE53408, GSE48149) was firstly downloaded from GEO database and subsequently integrated by Robust rank aggregation (RRA) method to screen robust differentially expressed genes (DEGs). Then functional annotation of robust DEGs was performed by GO and KEGG enrichment analysis. The protein-protein interaction (PPI) network was constructed followed by using MCODE and CytoHubba plug-in to identify hub genes. Finally, 10 hub genes were screened including ENO1, TALDO1, TXNRD1, SHMT2, IDH1, TKT, PGD, CXCL10, CXCL9, and CCL5. The GSE113439 dataset was used as a validation cohort to appraise these hub genes and TXNRD1 was selected for verification at the protein level. The experiment results confirmed that serum TXNRD1 concentration was lower in IPAH patients and the level of TXNRD1 had great predictive efficiency (AUC:0.795) as well as presents negative correlation with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR). Consistently, the expression of TXNRD1 was proved to be inhibited in animal and cellular model of PAH. In addition, GSEA analysis was performed to explore the functions of TXNRD1 and the results revealed that TXNRD1 was closely correlated with mTOR signaling pathway, MYC targets, and unfolded protein response. Finally, knockdown of TXNRD1 was shown to exacerbate proliferative disorder, migration and apoptosis resistance in PASMCs. In conclusion, our study demonstrates that TXNRD1 is a promising candidate biomarker for diagnosis of IPAH and plays an important role in PAH pathogenesis, although further research is necessary.

Inhibition of KIF23 Alleviates IPAH by Targeting Pyroptosis and Proliferation of PASMCs

Idiopathic pulmonary arterial hypertension (IPAH) is a progressive vascular disease with high mortality and heritability. Pyroptosis is a novel form of programmed cell death, and it is closely associated with IPAH. However, the roles of pyroptosis-related genes (PRGs) in IPAH are still largely unknown. In this study, we identified KIF23 as the most relevant gene for IPAH and pyroptosis, and its expression was significantly increased in pulmonary arterial smooth muscle cells (PASMCs) of IPAH. Besides, the pyroptosis level of PASMCs was also considerably upregulated in IPAH. Knockdown of KIF23 in PASMCs could significantly suppress the PASMCs’ pyroptosis and proliferation and then alleviate the increase in pulmonary arterial pressure, right ventricular hypertrophy, and pulmonary vascular resistance in IPAH. KIF23 regulated the expression of Caspase3, NLRP3, and HMGB1, and they were all involved in the PI3K/AKT and MAPK pathways, indicating that PI3K/AKT and MAPK pathways might participate in regulating PASMCs pyroptosis by KIF23. In conclusion, our study suggests that KIF23 may be a new therapeutic target for IPAH, which can alleviate the symptoms of IPAH by inhibiting the pyroptosis and proliferation of PASMCs.

ENO1 and Cancer

α-Enolase (ENO1), also known as 2-phospho-D-glycerate hydrolase, is a glycolytic enzyme that catalyzes the conversion of 2-phosphoglyceric acid to phosphoenolpyruvic acid during glycolysis. It is a multifunctional oncoprotein that is present both in cell surface and cytoplasm, contributing to hit seven out of ten “hallmarks of cancer.” ENO1's glycolytic function deregulates cellular energetic, sustains tumor proliferation, and inhibits cancer cell apoptosis. Moreover, ENO1 evades growth suppressors and helps tumors to avoid immune destruction. Besides, ENO1 “moonlights” on the cell surface and acts as a plasminogen receptor, promoting cancer invasion and metastasis by inducing angiogenesis. Overexpression of ENO1 on a myriad of cancer types together with its localization on the tumor surface makes it a great prognostic and diagnostic cancer biomarker as well as an accessible oncotherapeutic target. This review summarizes the up-to-date knowledge about the relationship between ENO1 and cancer, examines ENO1's potential as a cancer biomarker, and discusses ENO1's role in novel onco-immunotherapeutic strategies.

Signal Transduction during Metabolic and Inflammatory Reprogramming in Pulmonary Vascular Remodeling

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by (mal)adaptive remodeling of the pulmonary vasculature, which is associated with inflammation, fibrosis, thrombosis, and neovascularization. Vascular remodeling in PAH is associated with cellular metabolic and inflammatory reprogramming that induce profound endothelial and smooth muscle cell phenotypic changes. Multiple signaling pathways and regulatory loops act on metabolic and inflammatory mediators which influence cellular behavior and trigger pulmonary vascular remodeling in vivo. This review discusses the role of bioenergetic and inflammatory impairments in PAH development.

Metabolism, Mitochondrial Dysfunction, and Redox Homeostasis in Pulmonary Hypertension

Pulmonary hypertension (PH) represents a group of disorders characterized by elevated mean pulmonary artery (PA) pressure, progressive right ventricular failure, and often death. Some of the hallmarks of pulmonary hypertension include endothelial dysfunction, intimal and medial proliferation, vasoconstriction, inflammatory infiltration, and in situ thrombosis. The vascular remodeling seen in pulmonary hypertension has been previously linked to the hyperproliferation of PA smooth muscle cells. This excess proliferation of PA smooth muscle cells has recently been associated with changes in metabolism and mitochondrial biology, including changes in glycolysis, redox homeostasis, and mitochondrial quality control. In this review, we summarize the molecular mechanisms that have been reported to contribute to mitochondrial dysfunction, metabolic changes, and redox biology in PH.

Infantile hepatic hemangiomas: looking backwards and forwards

Infantile hepatic hemangiomas (IHHs) are common benign tumors seen in the liver of infants. IHHs are true infantile hemangiomas (IHs) and have phases of proliferation and involution parallel to those of cutaneous IHs. The definition and classification of IHH are still confusing in the literature. The mechanisms during the pathogenesis of IHH have yet to be discovered. The clinical manifestations of IHH are heterogeneous. Although most IHH lesions are asymptomatic, some lesions can lead to severe complications, such as hypothyroidism, consumptive coagulopathy, and high-output congestive cardiac failure. Consequently, some patients can possibly encounter a fatal clinical condition. The heterogeneity of the lesions and the occurrence of disease-related comorbidities can make the treatment of IHH challenging. Oral propranolol is emerging as an effective systemic approach to IHH with obvious responses in tumor remission and symptom regression. However, the precise clinical characteristics and treatment strategies for patients with severe IHH have not yet been well established. Here, we summarize the epidemiology, pathogenic mechanism, clinical manifestations, diagnosis, and treatment of IHH. Recent updates and future perspectives for IHH will also be elaborated.

Mitochondrial Metabolism, Redox, and Calcium Homeostasis in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by elevated pulmonary arterial pressure due to increased pulmonary vascular resistance, secondary to sustained pulmonary vasoconstriction and excessive obliterative pulmonary vascular remodeling. Work over the last decade has led to the identification of a critical role for metabolic reprogramming in the PAH pathogenesis. It is becoming clear that in addition to its role in ATP generation, the mitochondrion is an important organelle that regulates complex and integrative metabolic- and signal transduction pathways. This review focuses on mitochondrial metabolism alterations that occur in deranged pulmonary vessels and the right ventricle, including abnormalities in glycolysis and glucose oxidation, fatty acid oxidation, glutaminolysis, redox homeostasis, as well as iron and calcium metabolism. Further understanding of these mitochondrial metabolic mechanisms could provide viable therapeutic approaches for PAH patients.