Metabolic and Proliferative State of Vascular Adventitial Fibroblasts in Pulmonary Hypertension Is Regulated Through a MicroRNA-124/PTBP1 (Polypyrimidine Tract Binding Protein 1)/Pyruvate Kinase Muscle Axis

MicroRNA-210 mediates hypoxia-induced pulmonary hypertension by targeting mitochondrial bioenergetics and mtROS flux

AIM

Chronic hypoxia is a common cause of pulmonary hypertension (PH). We test the hypothesis that microRNA-210 (miR-210) mediates hypoxia-induced PH by targeting mitochondrial metabolism and increasing reactive oxygen species (mtROS) production in the lungs.

METHODS

Adult wildtype (WT) or miR-210 knockout (KO) mice were exposed to hypoxia (10.5% O2) or normoxia for 4 weeks. We measured miR-210 levels, right ventricular systolic pressure (RVSP), and histological changes in heart and lung tissues. Mitochondrial bioenergetics and mtROS production were assessed in isolated lung mitochondria.

RESULTS

Hypoxia increased right ventricular wall thickness and pulmonary vessel wall muscularization in WT, but not miR-210 KO mice. No sex differences were observed. In male mice, hypoxia increased miR-210 levels in the lung and RVSP, which were abrogated by miR-210 deficiency. Hypoxia upregulated mitochondrial oxygen consumption rate and mtROS flux, which were negated in miR-210 KO animals. In addition, chronic hypoxia increased macrophage accumulation in lungs of WT, but not miR-210 KO mice. Moreover, miR-210 overexpression in lungs of WT animals recapitulated the effects of hypoxia and increased mitochondrial oxygen consumption rate, mtROS flux, right ventricular wall thickness, pulmonary vessel wall muscularization and RVSP. MitoQ revoked the effects of miR-210 on lung mitochondrial bioenergetics, right ventricular and pulmonary vessel remodeling and RVSP.

CONCLUSION

Our findings with loss-of-function and gain-of-function approaches provide explicit evidence that miR-210 mediates hypoxia-induced PH by upregulating mitochondrial bioenergetics and mtROS production in a murine model, revealing new insights into the mechanisms and therapeutic targets for treatment of PH.

Tetramerization of PKM2 Alleviates Traumatic Brain Injury by Ameliorating Mitochondrial Damage in Microglia

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Microglial activation and neuroinflammation are key cellular events that determine the outcome of TBI, especially neuronal and cognitive function. Studies have suggested that the metabolic characteristics of microglia dictate their inflammatory response. The pyruvate kinase isoform M2 (PKM2), a key glycolytic enzyme, is involved in the regulation of various cellular metabolic processes, including mitochondrial metabolism. This suggests that PKM2 may also participate in the regulation of microglial activation during TBI. Therefore, the present study aimed to evaluate the role of PKM2 in regulating microglial activation and neuroinflammation and its effects on cognitive function following TBI. A controlled cortical impact (CCI) mouse model and inflammation-induced primary mouse microglial cells in vitro were used to investigate the potential effects of PKM2 inhibition and regulation. PKM2 was significantly increased during the acute and subacute phases of TBI and was predominantly detected in microglia rather than in neurons. Our results demonstrate that shikonin and TEPP-46 can inhibit microglial inflammation, improving mitochondria, improving mouse behavior, reducing brain defect volume, and alleviating pathological changes after TBI. There is a difference in the intervention of shikonin and TEPP-46 on PKM2. Shikonin directly inhibits General PKM2; TEPP-46 can promote the expression of PKM2 tetramer. In vitro experiments, TEPP-46 can promote the expression of PKM2 tetramer, enhance the interaction between PKM2 and MFN2, improve mitochondria, alleviate neuroinflammation. General inhibition and tetramerization activation of PKM2 attenuated cognitive function caused by TBI, whereas PKM2 tetramerization exhibited a better treatment effect. Our experiments demonstrated the non-metabolic role of PKM2 in the regulation of microglial activation following TBI. Both shikonin and TEPP-46 can inhibit pro-inflammatory factors, but only TEPP-46 can promote PKM2 tetramerization and upregulate the release of anti-inflammatory factors from microglia.

Compound 3K attenuates isoproterenol-induced cardiac hypertrophy by inhibiting pyruvate kinase M2 (PKM2) pathway

AIM

Chronic sympathetic stimulation has been identified as a primary factor in the pathogenesis of cardiac hypertrophy (CH). However, there is no appropriate treatment available for the management of CH. Recently, it has been revealed that pyruvate kinase M2 (PKM2) plays a significant role in cardiac remodeling, fibrosis, and hypertrophy. However, the therapeutic potential of selective PKM2 inhibitor has not yet been explored in cardiac hypertrophy. Thus, in the current study, we have studied the cardioprotective potential of Compound 3K, a selective PKM2 inhibitor in isoproterenol-induced CH model.

METHODS

To induce cardiac hypertrophy, male Wistar rats were subcutaneously administered isoproterenol (ISO, 5 mg/kg/day) for 14 days. Compound 3K at dosages of 2 and 4 mg/kg orally was administered to ISO-treated rats for 14 days to explore its effects on various parameters like ECG, ventricular functions, hypertrophic markers, histology, inflammation, and protein expression were performed.

RESULTS

Fourteen days administration of ISO resulted in the induction of CH, which was evidenced by alterations in ECG, ventricular dysfunctions, increase in hypertrophy markers, and fibrosis. The immunoblotting of hypertrophy heart revealed the significant rise in PKM2 and reduction in PKM1 protein expression. Treatment with Compound 3K led to downregulation of PKM2 and upregulation of PKM1 protein expression. Compound 3K showed cardioprotective effects by improving ECG, cardiac functions, hypertrophy markers, inflammation, and fibrosis. Further, it also reduced cardiac expression of PKM2-associated splicing protein, HIF-1α, and caspase-3.

CONCLUSION

Our findings suggest that Compound 3K has a potential cardioprotective effect via PKM2 inhibition in isoproterenol-induced CH.

The Role of PKM2 in Multiple Signaling Pathways Related to Neurological Diseases

Pyruvate kinase M2 (PKM2) is a key rate-limiting enzyme in glycolysis. It is well known that PKM2 plays a vital role in the proliferation of tumor cells. However, PKM2 can also exert its biological functions by mediating multiple signaling pathways in neurological diseases, such as Alzheimer's disease (AD), cognitive dysfunction, ischemic stroke, post-stroke depression, cerebral small-vessel disease, hypoxic-ischemic encephalopathy, traumatic brain injury, spinal cord injury, Parkinson's disease (PD), epilepsy, neuropathic pain, and autoimmune diseases. In these diseases, PKM2 can exert various biological functions, including regulation of glycolysis, inflammatory responses, apoptosis, proliferation of cells, oxidative stress, mitochondrial dysfunction, or pathological autoimmune responses. Moreover, the complexity of PKM2's biological characteristics determines the diversity of its biological functions. However, the role of PKM2 is not entirely the same in different diseases or cells, which is related to its oligomerization, subcellular localization, and post-translational modifications. This article will focus on the biological characteristics of PKM2, the regulation of PKM2 expression, and the biological role of PKM2 in neurological diseases. With this review, we hope to have a better understanding of the molecular mechanisms of PKM2, which may help researchers develop therapeutic strategies in clinic.

Emerging connectivity of programmed cell death pathways and pulmonary vascular remodelling during pulmonary hypertension

Pulmonary hypertension (PH) is a chronic progressive vascular disease characterized by abnormal pulmonary vascular resistance and pulmonary artery pressure. The major structural alteration during PH is pulmonary vascular remodelling, which is mainly caused by the imbalance between proliferation and apoptosis of pulmonary vascular cells. Previously, it was thought that apoptosis was the only type of programmed cell death (PCD). Soon afterward, other types of PCD have been identified, including autophagy, pyroptosis, ferroptosis and necroptosis. In this review, we summarize the role of the above five forms of PCD in mediating pulmonary vascular remodelling, and discuss their guiding significance for PH treatment. The current review could provide a better understanding of the correlation between PCD and pulmonary vascular remodelling, contributing to identify new PCD-associated drug targets for PH.

Smooth Muscle Ythdf2 Abrogation Ameliorates Pulmonary Vascular Remodeling by Regulating Myadm Transcript Stability

BACKGROUND

The N6-methyladenosine (m6A) modification of RNA and its regulators have important roles in the pathogenesis of pulmonary hypertension (PH). Ythdf2 (YTH N6-methyladenosine RNA binding protein 2) is best known for its role in degrading m6A-modified mRNAs such as Hmox1 mRNA, which leads to alternative activation of macrophages in PH. Recent studies have also linked Ythdf2 to the proliferation of pulmonary artery smooth muscle cells (PASMCs). However, its specific roles in PASMCs and downstream targets during the development of PH remain unclear.

METHODS

The expression and biological function of Ythdf2 in PASMCs were investigated in human and experimental models of PH. Smooth muscle cell-specific Ythdf2-deficient mice were used to assess the roles of Ythdf2 in PASMCs in vivo. Proteomic analysis, m6A sequencing, and RNA immunoprecipitation analysis were used to screen for potential downstream targets.

RESULTS

Ythdf2 was significantly upregulated in human and rodent PH-PASMCs, and smooth muscle cell-specific Ythdf2 deficiency ameliorated PASMC proliferation, right ventricular hypertrophy, pulmonary vascular remodeling, and PH development. Higher expression of Ythdf2 promoted PASMC proliferation and PH by paradoxically stabilizing Myadm mRNA in an m6A-dependent manner. Loss of Ythdf2 decreased the expression of Myadm in PASMCs and pulmonary arteries, both in vitro and in vivo. Additionally, silencing Myadm inhibited the Ythdf2-dependent hyperproliferation of PASMCs by upregulating the cell cycle kinase inhibitor p21.

CONCLUSIONS

We have identified a novel mechanism where the increased expression of Ythdf2 stimulates PH-PASMC proliferation through an m6A/Myadm/p21 pathway. Strategies targeting Ythdf2 in PASMCs might be useful additions to the therapeutic approach to PH.

Pyruvate Kinase M2: A Potential Regulator of Cardiac Injury Through Glycolytic and Non-glycolytic Pathways

ABSTRACT

Adult animals are unable to regenerate heart cells due to postnatal cardiomyocyte cycle arrest, leading to higher mortality rates in cardiomyopathy. However, reprogramming of energy metabolism in cardiomyocytes provides a new perspective on the contribution of glycolysis to repair, regeneration, and fibrosis after cardiac injury. Pyruvate kinase (PK) is a key enzyme in the glycolysis process. This review focuses on the glycolysis function of PKM2, although PKM1 and PKM2 both play significant roles in the process after cardiac injury. PKM2 exists in both low-activity dimer and high-activity tetramer forms. PKM2 dimers promote aerobic glycolysis but have low catalytic activity, leading to the accumulation of glycolytic intermediates. These intermediates enter the pentose phosphate pathway to promote cardiomyocyte proliferation and heart regeneration. Additionally, they activate adenosine triphosphate (ATP)-sensitive K + (K ATP ) channels, protecting the heart against ischemic damage. PKM2 tetramers function similar to PKM1 in glycolysis, promoting pyruvate oxidation and subsequently ATP generation to protect the heart from ischemic damage. They also activate KDM5 through the accumulation of αKG, thereby promoting cardiomyocyte proliferation and cardiac regeneration. Apart from glycolysis, PKM2 interacts with transcription factors like Jmjd4, RAC1, β-catenin, and hypoxia-inducible factor (HIF)-1α, playing various roles in homeostasis maintenance, remodeling, survival regulation, and neovascularization promotion. However, PKM2 has also been implicated in promoting cardiac fibrosis through mechanisms like sirtuin (SIRT) 3 deletion, TG2 expression enhancement, and activation of transforming growth factor-β1 (TGF-β1)/Smad2/3 and Jak2/Stat3 signals. Overall, PKM2 shows promising potential as a therapeutic target for promoting cardiomyocyte proliferation and cardiac regeneration and addressing cardiac fibrosis after injury.

Pyruvate kinase M2 sustains cardiac mitochondrial quality surveillance in septic cardiomyopathy by regulating prohibitin 2 abundance via S91 phosphorylation

The endogenous mitochondrial quality control (MQC) system serves to protect mitochondria against cellular stressors. Although mitochondrial dysfunction contributes to cardiac damage during many pathological conditions, the regulatory signals influencing MQC disruption during septic cardiomyopathy (SC) remain unclear. This study aimed to investigate the involvement of pyruvate kinase M2 (PKM2) and prohibitin 2 (PHB2) interaction followed by MQC impairment in the pathogenesis of SC. We utilized LPS-induced SC models in PKM2 transgenic (PKM2TG) mice, PHB2S91D-knockin mice, and PKM2-overexpressing HL-1 cardiomyocytes. After LPS-induced SC, cardiac PKM2 expression was significantly downregulated in wild-type mice, whereas PKM2 overexpression in vivo sustained heart function, suppressed myocardial inflammation, and attenuated cardiomyocyte death. PKM2 overexpression relieved sepsis-related mitochondrial damage via MQC normalization, evidenced by balanced mitochondrial fission/fusion, activated mitophagy, restored mitochondrial biogenesis, and inhibited mitochondrial unfolded protein response. Docking simulations, co-IP, and domain deletion mutant protein transfection experiments showed that PKM2 phosphorylates PHB2 at Ser91, preventing LPS-mediated PHB2 degradation. Additionally, the A domain of PKM2 and the PHB domain of PHB2 are required for PKM2-PHB2 binding and PHB2 phosphorylation. After LPS exposure, expression of a phosphorylation-defective PHB2S91A mutant negated the protective effects of PKM2 overexpression. Moreover, knockin mice expressing a phosphorylation-mimetic PHB2S91D mutant showed improved heart function, reduced inflammation, and preserved mitochondrial function following sepsis induction. Abundant PKM2 expression is a prerequisite to sustain PKM2-PHB2 interaction which is a key element for preservation of PHB2 phosphorylation and MQC, presenting novel interventive targets for the treatment of septic cardiomyopathy.

Dietary intake and glutamine-serine metabolism control pathologic vascular stiffness

Perivascular collagen deposition by activated fibroblasts promotes vascular stiffening and drives cardiovascular diseases such as pulmonary hypertension (PH). Whether and how vascular fibroblasts rewire their metabolism to sustain collagen biosynthesis remains unknown. Here, we found that inflammation, hypoxia, and mechanical stress converge on activating the transcriptional coactivators YAP and TAZ (WWTR1) in pulmonary arterial adventitial fibroblasts (PAAFs). Consequently, YAP and TAZ drive glutamine and serine catabolism to sustain proline and glycine anabolism and promote collagen biosynthesis. Pharmacologic or dietary intervention on proline and glycine anabolic demand decreases vascular stiffening and improves cardiovascular function in PH rodent models. By identifying the limiting metabolic pathways for vascular collagen biosynthesis, our findings provide guidance for incorporating metabolic and dietary interventions for treating cardiopulmonary vascular disease.

HMGB2 Release Promotes Pulmonary Hypertension and Predicts Severity and Mortality of Patients With Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary hypertension (PH) is a progressive and life-threatening disease characterized by pulmonary vascular remodeling, which involves aberrant proliferation and apoptosis resistance of the pulmonary arterial smooth muscle cells (PASMCs), resembling the hallmark characteristics of cancer. In cancer, the HMGB2 (high-mobility group box 2) protein promotes the pro-proliferative/antiapoptotic phenotype. However, the function of HMGB2 in PH remains uninvestigated.

METHODS

Smooth muscle cell (SMC)-specific HMGB2 knockout or HMGB2-OE (HMGB2 overexpression) mice and HMGB2 silenced rats were used to establish hypoxia+Su5416 (HySu)-induced PH mouse and monocrotaline-induced PH rat models, respectively. The effects of HMGB2 and its underlying mechanisms were subsequently elucidated using RNA-sequencing and cellular and molecular biology analyses. Serum HMGB2 levels were measured in the controls and patients with pulmonary arterial (PA) hypertension.

RESULTS

HMGB2 expression was markedly increased in the PAs of patients with PA hypertension and PH rodent models and was predominantly localized in PASMCs. SMC-specific HMGB2 deficiency or silencing attenuated PH development and pulmonary vascular remodeling in hypoxia+Su5416-induced mice and monocrotaline-treated rats. SMC-specific HMGB2 overexpression aggravated hypoxia+Su5416-induced PH. HMGB2 knockdown inhibited PASMC proliferation in vitro in response to PDGF-BB (platelet-derived growth factor-BB). In contrast, HMGB2 protein stimulation caused the hyperproliferation of PASMCs. In addition, HMGB2 promoted PASMC proliferation and the development of PH by RAGE (receptor for advanced glycation end products)/FAK (focal adhesion kinase)-mediated Hippo/YAP (yes-associated protein) signaling suppression. Serum HMGB2 levels were significantly increased in patients with PA hypertension, and they correlated with disease severity, predicting worse survival.

CONCLUSIONS

Our findings indicate that targeting HMGB2 might be a novel therapeutic strategy for treating PH. Serum HMGB2 levels could serve as a novel biomarker for diagnosing PA hypertension and determining its prognosis.

Unveiling the metabolic landscape of pulmonary hypertension: insights from metabolomics

Pulmonary hypertension (PH) is regarded as cardiovascular disease with an extremely poor prognosis, primarily due to irreversible vascular remodeling. Despite decades of research progress, the absence of definitive curative therapies remains a critical challenge, leading to high mortality rates. Recent studies have shown that serious metabolic disorders generally exist in PH animal models and patients of PH, which may be the cause or results of the disease. It is imperative for future research to identify critical biomarkers of metabolic dysfunction in PH pathophysiology and to uncover metabolic targets that could enhance diagnostic and therapeutic strategies. Metabolomics offers a powerful tool for the comprehensive qualitative and quantitative analysis of metabolites within specific organisms or cells. On the basis of the findings of the metabolomics research on PH, this review summarizes the latest research progress on metabolic pathways involved in processes such as amino acid metabolism, carbohydrate metabolism, lipid metabolism, and nucleotide metabolism in the context of PH.

Fibroblasts in Pulmonary Hypertension: Roles and Molecular Mechanisms

Fibroblasts, among the most prevalent and widely distributed cell types in the human body, play a crucial role in defining tissue structure. They do this by depositing and remodeling extracellular matrixes and organizing functional tissue networks, which are essential for tissue homeostasis and various human diseases. Pulmonary hypertension (PH) is a devastating syndrome with high mortality, characterized by remodeling of the pulmonary vasculature and significant cellular and structural changes within the intima, media, and adventitia layers. Most research on PH has focused on alterations in the intima (endothelial cells) and media (smooth muscle cells). However, research over the past decade has provided strong evidence of the critical role played by pulmonary artery adventitial fibroblasts in PH. These fibroblasts exhibit the earliest, most dramatic, and most sustained proliferative, apoptosis-resistant, and inflammatory responses to vascular stress. This review examines the aberrant phenotypes of PH fibroblasts and their role in the pathogenesis of PH, discusses potential molecular signaling pathways underlying these activated phenotypes, and highlights areas of research that merit further study to identify promising targets for the prevention and treatment of PH.

The Regulatory Network of hnRNPs Underlying Regulating PKM Alternative Splicing in Tumor Progression

One of the hallmarks of cancer is metabolic reprogramming in tumor cells, and aerobic glycolysis is the primary mechanism by which glucose is quickly transformed into lactate. As one of the primary rate-limiting enzymes, pyruvate kinase (PK) M is engaged in the last phase of aerobic glycolysis. Alternative splicing is a crucial mechanism for protein diversity, and it promotes PKM precursor mRNA splicing to produce PKM2 dominance, resulting in low PKM1 expression. Specific splicing isoforms are produced in various tissues or illness situations, and the post-translational modifications are linked to numerous disorders, including cancers. hnRNPs are one of the main components of the splicing factor families. However, there have been no comprehensive studies on hnRNPs regulating PKM alternative splicing. Therefore, this review focuses on the regulatory network of hnRNPs on PKM pre-mRNA alternative splicing in tumors and clinical drug research. We elucidate the role of alternative splicing in tumor progression, prognosis, and the potential mechanism of abnormal RNA splicing. We also summarize the drug targets retarding tumorous splicing events, which may be critical to improving the specificity and effectiveness of current therapeutic interventions.

Functions and novel regulatory mechanisms of key glycolytic enzymes in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive vascular disease characterized by remodeling of the pulmonary vasculature and elevated pulmonary arterial pressure, ultimately leading to right heart failure and death. Despite its clinical significance, the precise molecular mechanisms driving PAH pathogenesis warrant confirmation. Compelling evidence indicates that during the development of PAH, pulmonary vascular cells exhibit a preference for energy generation through aerobic glycolysis, known as the "Warburg effect", even in well-oxygenated conditions. This metabolic shift results in imbalanced metabolism, increased proliferation, and severe pulmonary vascular remodeling. Exploring the Warburg effect and its interplay with glycolytic enzymes in the context of PAH has yielded current insights into emerging drug candidates targeting enzymes and intermediates involved in glucose metabolism. This sheds light on both opportunities and challenges in the realm of antiglycolytic therapy for PAH.

Rare diseases and pyruvate kinase M2: a promising therapeutic connection

Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme that regulates proliferating cell metabolism. The role of PKM2 in common diseases has been well established, but its role in rare diseases (RDs) is less understood. Over the past few years, PKM2 has emerged as a crucial player in RDs, including, neoplastic, respiratory, metabolic, and neurological disorders. Herein, we summarize recent findings and developments highlighting PKM2 as an emerging key player in RDs. We also discuss the current status of PKM2 modulation in RDs with particular emphasis on preclinical and clinical studies in addition to current challenges in the field.

Novel insights and new therapeutic potentials for macrophages in pulmonary hypertension

Inflammation and immune processes underlie pulmonary hypertension progression. Two main different activated phenotypes of macrophages, classically activated M1 macrophages and alternatively activated M2 macrophages, are both involved in inflammatory processes related to pulmonary hypertension. Recent advances suggest that macrophages coordinate interactions among different proinflammatory and anti-inflammatory mediators, and other cellular components such as smooth muscle cells and fibroblasts. In this review, we summarize the current literature on the role of macrophages in the pathogenesis of pulmonary hypertension, including the origin of pulmonary macrophages and their response to triggers of pulmonary hypertension. We then discuss the interactions among macrophages, cytokines, and vascular adventitial fibroblasts in pulmonary hypertension, as well as the potential therapeutic benefits of macrophages in this disease. Identifying the critical role of macrophages in pulmonary hypertension will contribute to a comprehensive understanding of this pathophysiological abnormality, and may provide new perspectives for pulmonary hypertension management.

Search progress of pyruvate kinase M2 (PKM2) in organ fibrosis

Fibrosis is characterized by abnormal deposition of the extracellular matrix (ECM), leading to organ structural remodeling and loss of function. The principal cellular effector in fibrosis is activated myofibroblasts, which serve as the main source of matrix proteins. Metabolic reprogramming, transitioning from mitochondrial oxidative phosphorylation to aerobic glycolysis, is widely observed in rapidly dividing cells such as tumor cells and activated myofibroblasts and is increasingly recognized as a fundamental pathogenic basis in organ fibrosis. Targeting metabolism represents a promising strategy to mitigate fibrosis. PKM2, a key enzyme in glycolysis, plays a pivotal role in metabolic reprogramming through allosteric regulation, impacting both metabolic and non-metabolic pathways. Therefore, metabolic reprogramming induced by PKM2 activation is involved in the occurrence and development of fibrosis in various organs. A comprehensive understanding of the role of PKM2 in fibrotic diseases is crucial for seeking new anti-fibrotic therapeutic targets. In this context, we summarize PKM2's role in glycolysis, mediating the intricate mechanisms underlying fibrosis in multiple organs, and discuss the potential value of PKM2 inhibitors and allosteric activators in future clinical treatments, aiming to identify novel therapeutic targets for proliferative fibrotic diseases.

The pharmaco-epigenetics of hypertension: a focus on microRNA

Hypertension is a major harbinger of cardiovascular morbidity and mortality. It predisposes to higher rates of myocardial infarction, chronic kidney failure, stroke, and heart failure than most other risk factors. By 2025, the prevalence of hypertension is projected to reach 1.5 billion people. The pathophysiology of this disease is multifaceted, as it involves nitric oxide and endothelin dysregulation, reactive oxygen species, vascular smooth muscle proliferation, and vessel wall calcification, among others. With the advent of new biomolecular techniques, various studies have elucidated a gaping hole in the etiology and mechanisms of hypertension. Indeed, epigenetics, DNA methylation, histone modification, and microRNA-mediated translational silencing appear to play crucial roles in altering the molecular phenotype into a hypertensive profile. Here, we critically review the experimentally determined associations between microRNA (miRNA) molecules and hypertension pharmacotherapy. Particular attention is given to the epigenetic mechanisms underlying the physiological responses to antihypertensive drugs like candesartan, and other relevant drugs like clopidogrel, aspirin, and statins among others. Furthermore, how miRNA affects the pharmaco-epigenetics of hypertension is especially highlighted.

Early Leishmania infectivity depends on miR-372/373/520d family-mediated reprogramming of polyamines metabolism in THP-1-derived macrophages

Leishmania amazonensis is a protozoan that primarily causes cutaneous leishmaniasis in humans. The parasite relies on the amino acid arginine to survive within macrophages and establish infection, since it is a precursor for producing polyamines. On the other hand, arginine can be metabolized via nitric oxide synthase 2 (NOS2) to produce the microbicidal molecule nitric oxide (NO), although this mechanism does not apply to human macrophages since they lack NOS2 activity. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at posttranscriptional levels. Our previous work showed that mmu-miR-294 targets Nos2 favoring Leishmania survival in murine macrophages. Here, we demonstrate that human macrophages upregulate the hsa-miR-372, hsa-miR-373, and hsa-miR-520d, which present the same seed sequence as the murine mmu-miR-294. Inhibition of the miR-372 impaired Leishmania survival in THP-1 macrophages and the effect was further enhanced with combinatorial inhibition of the miR-372/373/520d family, pointing to a cooperative mechanism. However, this reduction in survival is not caused by miRNA-targeting of NOS2, since the seed-binding motif found in mice is not conserved in the human 3'UTR. Instead, we showed the miR-372/373/520d family targeting the macrophage's main arginine transporter SLC7A2/CAT2 during infection. Arginine-related metabolism was markedly altered in response to infection and miRNA inhibition, as measured by Mass Spectrometry-based metabolomics. We found that Leishmania infection upregulates polyamines production in macrophages, as opposed to simultaneous inhibition of miR-372/373/520d, which decreased putrescine and spermine levels compared to the negative control. Overall, our study demonstrates miRNA-dependent modulation of polyamines production, establishing permissive conditions for intracellular parasite survival. Although the effector mechanisms causing host cell immunometabolic adaptations involve various parasite and host-derived signals, our findings suggest that the miR-372/373/520d family may represent a potential target for the development of new therapeutic strategies against cutaneous leishmaniasis.

Post-translational protein lactylation modification in health and diseases: a double-edged sword

As more is learned about lactate, it acts as both a product and a substrate and functions as a shuttle system between different cell populations to provide the energy for sustaining tumor growth and proliferation. Recent discoveries of protein lactylation modification mediated by lactate play an increasingly significant role in human health (e.g., neural and osteogenic differentiation and maturation) and diseases (e.g., tumors, fibrosis and inflammation, etc.). These views are critically significant and first described in detail in this review. Hence, here, we focused on a new target, protein lactylation, which may be a "double-edged sword" of human health and diseases. The main purpose of this review was to describe how protein lactylation acts in multiple physiological and pathological processes and their potential mechanisms through an in-depth summary of preclinical in vitro and in vivo studies. Our work aims to provide new ideas for treating different diseases and accelerate translation from bench to bedside.

Pulmonary hypertension

Pulmonary hypertension encompasses a range of conditions directly or indirectly leading to elevated pressures within the pulmonary arteries. Five main groups of pulmonary hypertension are recognized, all defined by a mean pulmonary artery pressure of >20 mmHg: pulmonary arterial hypertension (rare), pulmonary hypertension associated with left-sided heart disease (very common), pulmonary hypertension associated with lung disease (common), pulmonary hypertension associated with pulmonary artery obstructions, usually related to thromboembolic disease (rare), and pulmonary hypertension with unclear and/or multifactorial mechanisms (rare). At least 1% of the world's population is affected, with a greater burden more likely in low-income and middle-income countries. Across all its forms, pulmonary hypertension is associated with adverse vascular remodelling with obstruction, stiffening and vasoconstriction of the pulmonary vasculature. Without proactive management this leads to hypertrophy and ultimately failure of the right ventricle, the main cause of death. In older individuals, dyspnoea is the most common symptom. Stepwise investigation precedes definitive diagnosis with right heart catheterization. Medical and surgical treatments are approved for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. There are emerging treatments for other forms of pulmonary hypertension; but current therapy primarily targets the underlying cause. There are still major gaps in basic, clinical and translational knowledge; thus, further research, with a focus on vulnerable populations, is needed to better characterize, detect and effectively treat all forms of pulmonary hypertension.

Metabolomic analysis of Drosophila melanogaster larvae lacking pyruvate kinase

Pyruvate kinase (Pyk) is a rate-limiting enzyme that catalyzes the final metabolic reaction in glycolysis. The importance of this enzyme, however, extends far beyond ATP production, as Pyk is also known to regulate tissue growth, cell proliferation, and development. Studies of this enzyme in Drosophila melanogaster are complicated by the fact that the fly genome encodes 6 Pyk paralogs whose functions remain poorly defined. To address this issue, we used sequence distance and phylogenetic approaches to demonstrate that the gene Pyk encodes the enzyme most similar to the mammalian Pyk orthologs, while the other 5 Drosophila Pyk paralogs have significantly diverged from the canonical enzyme. Consistent with this observation, metabolomic studies of 2 different Pyk mutant strains revealed that larvae lacking Pyk exhibit a severe block in glycolysis, with a buildup of glycolytic intermediates upstream of pyruvate. However, our analysis also unexpectedly reveals that pyruvate levels are unchanged in Pyk mutants, indicating that larval metabolism maintains pyruvate pool size despite severe metabolic limitations. Consistent with our metabolomic findings, a complementary RNA-seq analysis revealed that genes involved in lipid metabolism and protease activity are elevated in Pyk mutants, again indicating that loss of this glycolytic enzyme induces compensatory changes in other aspects of metabolism. Overall, our study provides both insight into how Drosophila larval metabolism adapts to disruption of glycolytic metabolism as well as immediate clinical relevance, considering that Pyk deficiency is the most common congenital enzymatic defect in humans.

Efficacy of Drpitor1a, a Dynamin-Related Protein 1 inhibitor, in Pulmonary Arterial Hypertension

Rationale

Dynamin-related protein 1 (Drp1), a large GTPase, mediates mitochondrial fission. Increased Drp1-mediated fission permits accelerated mitosis, contributing to hyperproliferation of pulmonary artery smooth muscle cells (PASMC), which characterizes pulmonary arterial hypertension (PAH). We developed a Drp1 inhibitor, Drpitor1a, and tested its ability to regress PAH.

Objectives

Assess Drpitor1a's efficacy and toxicity in: a)normal and PAH human PASMC (hPASMC); b)normal rats versus rats with established monocrotaline (MCT)-induced PAH.

Methods

Drpitor1a's effects on recombinant and endogenous Drp1-GTPase activity, mitochondrial fission, and cell proliferation were studied in hPASMCs (normal=3; PAH=5). Drpitor1a's pharmacokinetics and tissue concentrations were measured (n=3 rats/sex). In a pilot study (n=3-4/sex/dose), Drpitor1a (1mg/kg/48-hours, intravenous) reduced adverse PA remodeling only in females. Consequently, we compared Drpitor1a to vehicle in normal (n=6 versus 8) and MCT-PAH (n=9 and 11) females, respectively. Drpitor1a treatment began 17-days post-MCT with echocardiography and cardiac catheterization performed 28-29 days post-MCT.

Results

Drpitor1a inhibited recombinant and endogenous Drp1 GTPase activity, which was increased in PAH hPASMC. Drpitor1a inhibited mitochondrial fission and proliferation and induced apoptosis, in PAH hPASMC but not normal hPASMC. Drpitor1a tissue levels were higher in female versus male RVs. In MCT-PAH females, Drpitor1a regressed PA obstruction, lowered pulmonary vascular resistance, and improved RV function, without hematologic, renal, or hepatic toxicity.

Conclusions

Drpitor1a inhibits Drp1 GTPase, reduces mitochondrial fission, and inhibits cell proliferation in PAH hPASMC. Drpitor1a caused no toxicity in MCT-PAH and had no significant effect on normal rats or hPASMCs. Drpitor1a is a potential PAH therapeutic which displays an interesting therapeutic sexual dimorphism.

PTBP1 as a potential regulator of disease

Polypyrimidine tract-binding protein 1 (PTBP1) is a member of the heterogeneous nuclear ribonucleoprotein (hnRNP) family, which plays a key role in alternative splicing of precursor mRNA and RNA metabolism. PTBP1 is universally expressed in various tissues and binds to multiple downstream transcripts to interfere with physiological and pathological processes such as the tumor growth, body metabolism, cardiovascular homeostasis, and central nervous system damage, showing great prospects in many fields. The function of PTBP1 involves the regulation and interaction of various upstream molecules, including circular RNAs (circRNAs), microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These regulatory systems are inseparable from the development and treatment of diseases. Here, we review the latest knowledge regarding the structure and molecular functions of PTBP1 and summarize its functions and mechanisms of PTBP1 in various diseases, including controversial studies. Furthermore, we recommend future studies on PTBP1 and discuss the prospects of targeting PTBP1 in new clinical therapeutic approaches.

Cyclin D-CDK4 Disulfide Bond Attenuates Pulmonary Vascular Cell Proliferation

BACKGROUND

Pulmonary hypertension (PH) is a chronic vascular disease characterized, among other abnormalities, by hyperproliferative smooth muscle cells and a perturbed cellular redox and metabolic balance. Oxidants induce cell cycle arrest to halt proliferation; however, little is known about the redox-regulated effector proteins that mediate these processes. Here, we report a novel kinase-inhibitory disulfide bond in cyclin D-CDK4 (cyclin-dependent kinase 4) and investigate its role in cell proliferation and PH.

METHODS

Oxidative modifications of cyclin D-CDK4 were detected in human pulmonary arterial smooth muscle cells and human pulmonary arterial endothelial cells. Site-directed mutagenesis, tandem mass-spectrometry, cell-based experiments, in vitro kinase activity assays, in silico structural modeling, and a novel redox-dead constitutive knock-in mouse were utilized to investigate the nature and definitively establish the importance of CDK4 cysteine modification in pulmonary vascular cell proliferation. Furthermore, the cyclin D-CDK4 oxidation was assessed in vivo in the pulmonary arteries and isolated human pulmonary arterial smooth muscle cells of patients with pulmonary arterial hypertension and in 3 preclinical models of PH.

RESULTS

Cyclin D-CDK4 forms a reversible oxidant-induced heterodimeric disulfide dimer between C7/8 and C135, respectively, in cells in vitro and in pulmonary arteries in vivo to inhibit cyclin D-CDK4 kinase activity, decrease Rb (retinoblastoma) protein phosphorylation, and induce cell cycle arrest. Mutation of CDK4 C135 causes a kinase-impaired phenotype, which decreases cell proliferation rate and alleviates disease phenotype in an experimental mouse PH model, suggesting this cysteine is indispensable for cyclin D-CDK4 kinase activity. Pulmonary arteries and human pulmonary arterial smooth muscle cells from patients with pulmonary arterial hypertension display a decreased level of CDK4 disulfide, consistent with CDK4 being hyperactive in human pulmonary arterial hypertension. Furthermore, auranofin treatment, which induces the cyclin D-CDK4 disulfide, attenuates disease severity in experimental PH models by mitigating pulmonary vascular remodeling.

CONCLUSIONS

A novel disulfide bond in cyclin D-CDK4 acts as a rapid switch to inhibit kinase activity and halt cell proliferation. This oxidative modification forms at a critical cysteine residue, which is unique to CDK4, offering the potential for the design of a selective covalent inhibitor predicted to be beneficial in PH.

SIRT3 Is a Critical Regulator of Mitochondrial Function of Fibroblasts in Pulmonary Hypertension

Pulmonary hypertension (PH) is a heterogeneous and life-threatening cardiopulmonary disorder in which mitochondrial dysfunction is believed to drive pathogenesis, although the underlying mechanisms remain unclear. To determine if abnormal SIRT3 (sirtuin 3) activity is related to mitochondrial dysfunction in adventitial fibroblasts from patients with idiopathic pulmonary arterial hypertension (IPAH) and hypoxic PH calves (PH-Fibs) and whether SIRT3 could be a potential therapeutic target to improve mitochondrial function, SIRT3 concentrations in control fibroblasts, PH-Fibs, and lung tissues were determined using quantitative real-time PCR and western blot. SIRT3 deacetylase activity in cells and lung tissues was determined using western blot, immunohistochemistry staining, and immunoprecipitation. Glycolysis and mitochondrial function in fibroblasts were measured using respiratory analysis and fluorescence-lifetime imaging microscopy. The effects of restoring SIRT3 activity (by overexpression of SIRT3 with plasmid, activation SIRT3 with honokiol, and supplementation with the SIRT3 cofactor nicotinamide adenine dinucleotide [NAD+]) on mitochondrial protein acetylation, mitochondrial function, cell proliferation, and gene expression in PH-Fibs were also investigated. We found that SIRT3 concentrations were decreased in PH-Fibs and PH lung tissues, and its cofactor, NAD+, was also decreased in PH-Fibs. Increased acetylation in overall mitochondrial proteins and SIRT3-specific targets (MPC1 [mitochondrial pyruvate carrier 1] and MnSOD2 [mitochondrial superoxide dismutase]), as well as decreased MnSOD2 activity, was identified in PH-Fibs and PH lung tissues. Normalization of SIRT3 activity, by increasing its expression with plasmid or with honokiol and supplementation with its cofactor NAD+, reduced mitochondrial protein acetylation, improved mitochondrial function, inhibited proliferation, and induced apoptosis in PH-Fibs. Thus, our study demonstrated that restoration of SIRT3 activity in PH-Fibs can reduce mitochondrial protein acetylation and restore mitochondrial function and PH-Fib phenotype in PH.

Preventive effect of LCZ696 on hypoxic pulmonary hypertension in rats via regulating the PI3K/AKT signaling pathway

Hypoxic pulmonary hypertension (HPH) is a devastating disease worldwide; however, effective therapeutic drugs are lacking. This study investigated the effects and underlying mechanisms of LCZ696 treatment on hypoxia-induced pulmonary hypertension. Male Sprague-Dawley (SD) rats were kept in a hypobaric chamber with an oxygen concentration of 5% for 4 weeks. Rats were treated with either LCZ696 (18 mg/kg, 36 mg/kg, and 72 mg/kg) or sildenafil. The mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI), and lung system index were measured. Hematoxylin-eosin (HE) staining, Masson staining, and immunofluorescence staining were used for histological analysis. Enzyme linked immunosorbent assay (ELISA) kits were used to determine the concentrations of inflammatory and hypoxia-related factors. Western blotting was used to examine the expression of apoptotic and PI3K/AKT signaling pathway proteins in rat lung tissue. Hypoxia increased mPAP, RVHI, and lung system index and induced pulmonary vascular remodeling, pulmonary arteriomyosis, and pulmonary artery fibrosis. LCZ696 treatment reduced the increase in mPAP, RVHI, and the lung system index and ameliorated the induced pathological changes. Hypoxia upregulated expression of NF-kB, TNF-α, IL-6, HIF-1α, and Vascular endothelial growth factor (VEGF), decreased the ratio of Bax/Bcl-2, and activated the PI3K/AKT signaling pathway in lung tissue, and these effects were partially reversed by treatment with LCZ696. These results demonstrated that LCZ696 can ameliorate hypoxia-induced HPH by suppressing apoptosis, inhibiting the inflammatory response, and inhibiting the PI3K/AKT signaling pathway. It provides a reference for clinical rational drug use and lays a foundation for the study of HPH therapeutic drugs.

Unraveling the link between PTBP1 and severe asthma through machine learning and association rule mining method

Severe asthma is a chronic inflammatory airway disease with great therapeutic challenges. Understanding the genetic and molecular mechanisms of severe asthma may help identify therapeutic strategies for this complex condition. RNA expression data were analyzed using a combination of artificial intelligence methods to identify novel genes related to severe asthma. Through the ANOVA feature selection approach, 100 candidate genes were selected among 54,715 mRNAs in blood samples of patients with severe asthmatic and healthy groups. A deep learning model was used to validate the significance of the candidate genes. The accuracy, F1-score, AUC-ROC, and precision of the 100 genes were 83%, 0.86, 0.89, and 0.9, respectively. To discover hidden associations among selected genes, association rule mining was applied. The top 20 genes including the PTBP1, RAB11FIP3, APH1A, and MYD88 were recognized as the most frequent items among severe asthma association rules. The PTBP1 was found to be the most frequent gene associated with severe asthma among those 20 genes. PTBP1 was the gene most frequently associated with severe asthma among candidate genes. Identification of master genes involved in the initiation and development of asthma can offer novel targets for its diagnosis, prognosis, and targeted-signaling therapy.

Vascular wall microenvironment: exosomes secreted by adventitial fibroblasts induced vascular calcification

Vascular calcification often occurs in patients with chronic renal failure (CRF), which significantly increases the incidence of cardiovascular events in CRF patients. Our previous studies identified the crosstalk between the endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and the paracrine effect of VSMCs, which regulate the calcification of VSMCs. Herein, we aim to investigate the effects of exosomes secreted by high phosphorus (HPi) -induced adventitial fibroblasts (AFs) on the calcification of VSMCs and the underlying mechanism, which will further elucidate the important role of AFs in high phosphorus vascular wall microenvironment. The conditioned medium of HPi-induced AFs promotes the calcification of VSMCs, which is partially abrogated by GW4869, a blocker of exosomes biogenesis or release. Exosomes secreted by high phosphorus-induced AFs (AFsHPi-Exos) show similar effects on VSMCs. miR-21-5p is enriched in AFsHPi-Exos, and miR-21-5p enhances osteoblast-like differentiation of VSMCs by downregulating cysteine-rich motor neuron 1 (Crim1) expression. AFsHPi-Exos and exosomes secreted by AFs with overexpression of miR-21-5p (AFsmiR21M-Exos) significantly accelerate vascular calcification in CRF mice. In general, AFsHPi-Exos promote the calcification of VSMCs and vascular calcification by delivering miR-21-5p to VSMCs and subsequently inhibiting the expression of Crim1. Combined with our previous studies, the present experiment supports the theory of vascular wall microenvironment.

Role of micro-RNAs 21, 124 and other novel biomarkers in distinguishing between group 1 WHO pulmonary hypertension and group 2, 3 WHO pulmonary hypertension

BACKGROUND

Pulmonary hypertension "PH" is considered a serious cardiovascular disease. World Health Organization divided PH into groups depending on many factors like pathological, hemodynamic, and clinical pictures. Lately, various micro-RNAs "miRNAs" and other novel biomarkers like endoglin and asymmetric dimethylarginine "ADMA" might have a role in diagnosis of PH and may differentiate between pulmonary arterial hypertension "PAH" and non-PAH. The purpose of the study is to show the role of miR-21, miR-124, endoglin and ADMA in the diagnosis of PH and distinguishing between WHO group 1 PH and WHO group 2 and 3 PH and to identify patients who might benefit from non-invasive and inexpensive tools to diagnose PAH.

RESULTS

miR-21 was upregulated in group 1 PH, and there was significant difference between group 1 PH as compared with group 2 PH, group 3 PH and control; miR-124 was down-regulated in group 1 PH with highly significant difference between group 1 and group 2 PH and control but no significant difference with group 3 PH, endoglin was elevated in group 1 PH with a significant difference as compared to group 2 PH, group 3 PH and control. ADMA was elevated in group 1 PH as compared to control; however, there was no significant difference between it and group 2, 3 PH.

CONCLUSIONS

miR-21, miR-124, endoglin and ADMA are good biomarkers to diagnose PH; however, only miR-21 and endoglin could distinguish group 1 PH from group 2 and 3 PH.

Microenvironmental regulation of T-cells in pulmonary hypertension

Introduction

In pulmonary hypertension (PH), pulmonary arterial remodeling is often accompanied by perivascular inflammation. The inflammation is characterized by the accumulation of activated macrophages and lymphocytes within the adventitial stroma, which is comprised primarily of fibroblasts. The well-known ability of fibroblasts to secrete interleukins and chemokines has previously been implicated as contributing to this tissue-specific inflammation in PH vessels. We were interested if pulmonary fibroblasts from PH arteries contribute to microenvironmental changes that could activate and polarize T-cells in PH.

Methods

We used single-cell RNA sequencing of intact bovine distal pulmonary arteries (dPAs) from PH and control animals and flow cytometry, mRNA expression analysis, and respirometry analysis of blood-derived bovine/human T-cells exposed to conditioned media obtained from pulmonary fibroblasts of PH/control animals and IPAH/control patients (CM-(h)PH Fibs vs CM-(h)CO Fibs).

Results

Single-cell RNA sequencing of intact bovine dPAs from PH and control animals revealed a pro-inflammatory phenotype of CD4+ T-cells and simultaneous absence of regulatory T-cells (FoxP3+ Tregs). By exposing T-cells to CM-(h)PH Fibs we stimulated their proinflammatory differentiation documented by increased IFNγ and decreased IL4, IL10, and TGFβ mRNA and protein expression. Interestingly, we demonstrated a reduction in the number of suppressive T-cell subsets, i.e., human/bovine Tregs and bovine γδ T-cells treated with CM-(h)PH-Fibs. We also noted inhibition of anti-inflammatory cytokine expression (IL10, TGFβ, IL4). Pro-inflammatory polarization of bovine T-cells exposed to CM-PH Fibs correlated with metabolic shift to glycolysis and lactate production with increased prooxidant intracellular status as well as increased proliferation of T-cells. To determine whether metabolic reprogramming of PH-Fibs was directly contributing to the effects of PH-Fibs conditioned media on T-cell polarization, we treated PH-Fibs with the HDAC inhibitor SAHA, which was previously shown to normalize metabolic status and examined the effects of the conditioned media. We observed significant suppression of inflammatory polarization associated with decreased T-cell proliferation and recovery of mitochondrial energy metabolism.

Conclusion

This study demonstrates how the pulmonary fibroblast-derived microenvironment can activate and differentiate T-cells to trigger local inflammation, which is part of the vascular wall remodeling process in PH.

In vivo evaluation of the effect of sickle cell hemoglobin S, C and therapeutic transfusion on erythrocyte metabolism and cardiorenal dysfunction

Despite a wealth of exploratory plasma metabolomics studies in sickle cell disease (SCD), no study to date has evaluate a large and well phenotyped cohort to compare the primary erythrocyte metabolome of hemoglobin SS, SC and transfused AA red blood cells (RBCs) in vivo. The current study evaluates the RBC metabolome of 587 subjects with sickle cell sickle cell disease (SCD) from the WALK-PHaSST clinical cohort. The set includes hemoglobin SS, hemoglobin SC SCD patients, with variable levels of HbA related to RBC transfusion events. Here we explore the modulating effects of genotype, age, sex, severity of hemolysis, and transfusion therapy on sickle RBC metabolism. Results show that RBCs from patients with Hb SS genotypes-compared to AA RBCs from recent transfusion events or SC RBCs-are characterized by significant alterations of RBC acylcarnitines, pyruvate, sphingosine 1-phosphate, creatinine, kynurenine and urate metabolism. Surprisingly, the RBC metabolism of SC RBCs is dramatically different from SS, with all glycolytic intermediates significantly elevated in SS RBCs, with the exception of pyruvate. This result suggests a metabolic blockade at the ATP-generating phosphoenolpyruvate to pyruvate step of glycolysis, which is catalyzed by redox-sensitive pyruvate kinase. Metabolomics, clinical and hematological data were collated in a novel online portal. In conclusion, we identified metabolic signatures of HbS RBCs that correlate with the degree of steady state hemolytic anemia, cardiovascular and renal dysfunction and mortality.

Critical miRNAs in regulating pulmonary hypertension: A focus on Signaling pathways and therapeutic Targets

Pulmonary hypertension (PH) is complex disease as a result of obstructive pulmonary arterial remodeling, which in turn results in elevated pulmonary arterial pressure (PAP) and subsequent right ventricular heart failure, eventually leading to premature death. However, there is still a lack of a diagnostic blood-based biomarker and therapeutic target for PH. Because of the difficulty of diagnosis, new and more easily accessible prevention and treatment strategy are being explored. New target and diagnosis biomarkers should also allow for early diagnosis. In biology, miRNAs are short endogenous RNA molecules that are not coding. It is known that miRNAs can regulate gene expression and affect a variety of biological processes. Besides, miRNAs have been proven to be a crucial factor in PH pathogenesis. miRNAs have various effects on pulmonary vascular remodeling and are expressed differentially in various pulmonary vascular cells. Nowadays, it has been shown to be critical in the functions of different miRNAs in the pathogenesis of PH. Therefore, clarifying the mechanism of miRNAs regulating pulmonary vascular remodeling is of great importance to explore new therapeutic targets of PH and improve the survival qualify and time of patients. This review is focused on the role, mechanism, and potential therapeutic targets of miRNAs in PH and puts forward possible clinical treatment strategies.

Metabolomic analysis of Drosophila melanogaster larvae lacking Pyruvate kinase

Pyruvate kinase (Pyk) is a rate-limiting enzyme that catalyzes the final metabolic reaction in glycolysis. The importance of this enzyme, however, extends far beyond ATP production, as Pyk is also known to regulate tissue growth, cell proliferation, and development. Studies of this enzyme in Drosophila melanogaster , however, are complicated by the fact that the fly genome encodes six Pyk paralogs whose functions remain poorly defined. To address this issue, we used sequence distance and phylogenetic approaches to demonstrate that the gene Pyk encodes the enzyme most similar to the mammalian Pyk orthologs, while the other five Drosophila Pyk paralogs have significantly diverged from the canonical enzyme. Consistent with this observation, metabolomic studies of two different Pyk mutant backgrounds revealed that larvae lacking Pyk exhibit a severe block in glycolysis, with a buildup of glycolytic intermediates upstream of pyruvate. However, our analysis also unexpectedly reveals that steady state pyruvate levels are unchanged in Pyk mutants, indicating that larval metabolism maintains pyruvate pool size despite severe metabolic limitations. Consistent with our metabolomic findings, a complementary RNA-seq analysis revealed that genes involved in lipid metabolism and peptidase activity are elevated in Pyk mutants, again indicating that loss of this glycolytic enzyme induces compensatory changes in other aspects of metabolism. Overall, our study provides both insight into how Drosophila larval metabolism adapts to disruption of glycolytic metabolism as well as immediate clinical relevance, considering that Pyk deficiency is the most common congenital enzymatic defect in humans.

Novel lncRNA LNC_000113 Drives the Activation of Pulmonary Adventitial Fibroblasts through Modulating PTEN/Akt/FoxO1 Pathway

The activation of pulmonary adventitial fibroblasts (PAFs) is one of the key components of pulmonary arterial remodelling in pulmonary arterial hypertension (PAH). Emerging evidence indicates that lncRNAs may play fibrotic roles in a range of diseases. In this present study, we identified a novel lncRNA, LNC_000113, in pulmonary adventitial fibroblasts (PAFs) and characterised its role in the Galectin-3-induced activation of PAFs in rats. Galectin-3 led to elevated expression of lncRNA LNC_000113 in PAFs. The expression of this lncRNA was primarily PAF enriched. A progressive increase in lncRNA LNC_000113 expression was observed in rats with monocrotaline (MCT)-induced PAH rats. Knockdown of lncRNA LNC_000113 cancelled the Galectin-3's fibroproliferative effect on PAFs and prevented the transition of fibroblasts to myofibroblasts. The loss-of-function study demonstrated that lncRNA LNC_000113 activated PAFs through the PTEN/Akt/FoxO1 pathway. These results propose lncRNA LNC_000113 drives the activation of PAFs and promotes fibroblast phenotypic alterations.

MicroRNA and lncRNA as the Future of Pulmonary Arterial Hypertension Treatment

Pulmonary hypertension (PH) is characterized by a progressive increase in pulmonary arterial pressure and pulmonary vascular resistance. In a short time, it leads to right ventricular failure and, consequently, to death. The most common causes of PH include left heart disease and lung disease. Despite the significant development of medicine and related sciences observed in recent years, we still suffer from a lack of effective treatment that would significantly influence the prognosis and prolong life expectancy of patients with PH. One type of PH is pulmonary arterial hypertension (PAH). The pathophysiology of PAH is based on increased cell proliferation and resistance to apoptosis in the small pulmonary arteries, leading to pulmonary vascular remodeling. However, studies conducted in recent years have shown that epigenetic changes may also lie behind the pathogenesis of PAH. Epigenetics is the study of changes in gene expression that are not related to changes in the sequence of nucleotides in DNA. In addition to DNA methylation or histone modification, epigenetic research focuses on non-coding RNAs, which include microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Preliminary research results give hope that targeting epigenetic regulators may lead to new, potential therapeutic possibilities in the treatment of PAH.

PTBP1 promotes hepatocellular carcinoma progression by regulating the skipping of exon 9 in NUMB pre-mRNA

Aberrant alternative splicing is one of the important causes of cancer. Polypyrimidine tract binding protein 1 (PTBP1) has been found to be involved in splicing regulation in a variety of tumors. Here, we observed significant up-regulation of PTBP1 in primary hepatocellular carcinoma (HCC) tissues. High levels of PTBP1 expression were associated with poor prognosis and increased metastatic potential in HCC. In vitro studies demonstrated that elevated PTBP1 promoted both migration and invasion by HCC cells. In contrast, knockdown of PTBP1 significantly inhibited the migration and invasion of HCC cells in vitro. Further, up-regulation of PTBP1 markedly accumulated the expression of oncogenic isoform of NUMB, NUMB-PRR^L. We observed two isoforms of NUMB, NUMB-PRR^L and NUMB-PRR^S exhibit opposite function in HCC cells, which partially explain PTBP1 plays the tumor promoting roles in a NUMB splicing-dependent manner. In summary, our study indicates that PTBP1 may serve as an oncogene in HCC patients by regulating the alternative splicing of NUMB exon 9 and could potentially serve as a prognostic indicator.

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.

Purine synthesis suppression reduces the development and progression of pulmonary hypertension in rodent models

AIMS

Proliferation of vascular smooth muscle cells (VSMCs) is a hallmark of pulmonary hypertension (PH). Proliferative cells utilize purine bases from the de novo purine synthesis (DNPS) pathways for nucleotide synthesis; however, it is unclear whether DNPS plays a critical role in VSMC proliferation during development of PH. The last two steps of DNPS are catalysed by the enzyme 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC). This study investigated whether ATIC-driven DNPS affects the proliferation of pulmonary artery smooth muscle cells (PASMCs) and the development of PH.

METHODS AND RESULTS

Metabolites of DNPS in proliferative PASMCs were measured by liquid chromatography-tandem mass spectrometry. ATIC expression was assessed in platelet-derived growth factor-treated PASMCs and in the lungs of PH rodents and patients with pulmonary arterial hypertension. Mice with global and VSMC-specific knockout of Atic were utilized to investigate the role of ATIC in both hypoxia- and lung interleukin-6/hypoxia-induced murine PH. ATIC-mediated DNPS at the mRNA, protein, and enzymatic activity levels were increased in platelet-derived growth factor-treated PASMCs or PASMCs from PH rodents and patients with pulmonary arterial hypertension. In cultured PASMCs, ATIC knockdown decreased DNPS and nucleic acid DNA/RNA synthesis, and reduced cell proliferation. Global or VSMC-specific knockout of Atic attenuated vascular remodelling and inhibited the development and progression of both hypoxia- and lung IL-6/hypoxia-induced PH in mice.

CONCLUSION

Targeting ATIC-mediated DNPS compromises the availability of purine nucleotides for incorporation into DNA/RNA, reducing PASMC proliferation and pulmonary vascular remodelling and ameliorating the development and progression of PH.

Histone deacetylase inhibitors synergize with sildenafil to suppress purine metabolism and proliferation in pulmonary hypertension

RATIONALE

Sildenafil, a well-known vasodilator known to interfere with purinergic signaling through effects on cGMP, is a mainstay in the treatment of pulmonary hypertension (PH). However, little is known regarding its effects on the metabolic reprogramming of vascular cells, which is a hallmark of PH. Purine metabolism, especially intracellular de novo purine biosynthesis is essential for vascular cell proliferation. Since adventitial fibroblasts are critical contributors to proliferative vascular remodeling in PH, in this study we aimed to investigate if sildenafil, beyond its well-known vasodilator role in smooth muscle cells, impacts intracellular purine metabolism and proliferation of fibroblasts derived from human PH patients.

METHODS

Integrated omics approaches (plasma and cell metabolomics) and pharmacological inhibitor approaches were employed in plasma samples and cultured pulmonary artery fibroblasts from PH patients.

MEASUREMENTS AND MAIN RESULTS

Plasma metabolome analysis of 27 PH patients before and after treatment with sildenafil, demonstrated a partial, but specific effect of sildenafil on purine metabolites, especially adenosine, adenine, and xanthine. However, circulating markers of cell stress, including lactate, succinate, and hypoxanthine were only decreased in a small subset of sildenafil-treated patients. To better understand potential effects of sildenafil on pathological changes in purine metabolism (especially purine synthesis) in PH, we performed studies on pulmonary fibroblasts from PAH patients (PH-Fibs) and corresponding controls (CO-Fibs), since these cells have previously been shown to demonstrate stable and marked PH associated phenotypic and metabolic changes. We found that PH-Fibs exhibited significantly increased purine synthesis. Treatment of PH-Fibs with sildenafil was insufficient to normalize cellular metabolic phenotype and only modestly attenuated the proliferation. However, we observed that treatments which have been shown to normalize glycolysis and mitochondrial abnormalities including a PKM2 activator (TEPP-46), and the histone deacetylase inhibitors (HDACi), SAHA and Apicidin, had significant inhibitory effects on purine synthesis. Importantly, combined treatment with HDACi and sildenafil exhibited synergistic inhibitory effects on proliferation and metabolic reprogramming in PH-Fibs.

CONCLUSIONS

While sildenafil alone partially rescues metabolic alterations associated with PH, treatment with HDACi, in combination with sildenafil, represent a promising and potentially more effective strategy for targeting vasoconstriction, metabolic derangement and pathological vascular remodeling in PH.

Endothelial deletion of PTBP1 disrupts ventricular chamber development

The growth and maturation of the ventricular chamber require spatiotemporally precise synergy between diverse cell types. Alternative splicing deeply affects the processes. However, the functional properties of alternative splicing in cardiac development are largely unknown. Our study reveals that an alternative splicing factor polypyrimidine tract-binding protein 1 (PTBP1) plays a key role in ventricular chamber morphogenesis. During heart development, PTBP1 colocalizes with endothelial cells but is almost undetectable in cardiomyocytes. The endothelial-specific knockout of Ptbp1, in either endocardial cells or pan-endothelial cells, leads to a typical phenotype of left ventricular noncompaction (LVNC). Mechanistically, the deletion of Ptbp1 reduces the migration of endothelial cells, disrupting cardiomyocyte proliferation and ultimately leading to the LVNC. Further study shows that Ptbp1 deficiency changes the alternative splicing of β-arrestin-1 (Arrb1), which affects endothelial cell migration. In conclusion, as an alternative splicing factor, PTBP1 is essential during ventricular chamber development, and its deficiency can lead to congenital heart disease.

Inhibition of heterogeneous nuclear ribonucleoproteins A1 and oxidative stress reduces glycolysis via pyruvate kinase M2 in chronic thromboembolic pulmonary hypertension

Background and Objective

Chronic thromboembolic pulmonary hypertension (CTEPH) is a lethal complication of pulmonary embolism involving pulmonary artery occlusion and microvascular disease. The glucose metabolism and reactive oxygen species (ROS) production may be perturbed in CTEPH, but the precise mechanisms are unclear. This study investigated glucose metabolism in CTEPH employing pulmonary endarterectomy (PEA)-derived pulmonary artery smooth muscle cells (PASMCs) and characterized the roles of pyruvate kinase M2 (PKM2) and its regulation by heterogeneous nuclear ribonucleoproteins A1 (hnRNPA1) and ROS in CTEPH.

Methods

PEA tissues and blood samples of CTEPH patients were collected to study the levels of PKM2. Primary PASMCs were isolated from PEA tissues. We used small interfering RNAs to knock down PKM2 and hnRNPA1, and applied antioxidant N-acetylcysteine (NAC) and mito-TEMPO to reduce ROS production. The expression of glucometabolic genes, ROS production, glycolysis rate and proliferative and migratory activities were analyzed in PEA-derived PASMCs.

Results

PKM2 levels in serum and PEA tissues of CTEPH patients were higher than that of the healthy controls. Compared to the control PASMCs, PEA-derived PASMCs showed increased PKM2 expression and ROS production. The rates of glycolysis, proliferation and migration were increased in PEA-PASMCs and could be mitigated by PKM2 downregulation through hnRNPA1 or ROS inhibition.

Conclusions

Increased glycolysis and PKM2 expression were found in PEA-PASMCs. Inhibition of hnRNPA1 or ROS corrected the aberrant glycolysis, cell proliferation and migration by downregulating PKM2. Regulation of the hnRNPA1/PKM2 axis represents a potential therapeutic target for the treatment of CTEPH.

An Antisense Oligonucleotide-Loaded Blood-Brain Barrier Penetrable Nanoparticle Mediating Recruitment of Endogenous Neural Stem Cells for the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by the death of dopaminergic (DA) neurons and currently cannot be cured. One selected antisense oligonucleotide (ASO) is reported to be effective for the treatment of PD. However, ASO is usually intrathecally administered by lumbar puncture into the cerebral spinal fluid, through which the risks of highly invasive neurosurgery are the major concerns. In this study, ZAAM, an ASO-loaded, aptamer Apt 19S-conjugated, neural stem cell membrane (NSCM)-coated nanoparticle (NP), was developed for the targeted treatment of PD. NSCM facilitated the blood-brain barrier (BBB) penetration of NPs, and both NSCM and Apt 19S promoted the recruitment of the neural stem cells (NSCs) toward the PD site for DA neuron regeneration. The behavioral tests demonstrated that ZAAM highly improved the efficacy of ASO on PD by the targeted delivery of ASO and the recruitment of NSCs. This work is a heuristic report of (1) nonchemoattractant induced endogenous NSC recruitment, (2) NSCM-coated nanoparticles for the treatment of neurodegenerative diseases, and (3) systemic delivery of ASO for the treatment of PD. These findings provide insights into the development of biomimetic BBB penetrable drug carriers for precise diagnosis and therapy of central nervous system diseases.

Novel Molecular Mechanisms Involved in the Medical Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe condition with a high mortality rate despite advances in diagnostic and therapeutic strategies. In recent years, significant scientific progress has been made in the understanding of the underlying pathobiological mechanisms. Since current available treatments mainly target pulmonary vasodilation, but lack an effect on the pathological changes that develop in the pulmonary vasculature, there is need to develop novel therapeutic compounds aimed at antagonizing the pulmonary vascular remodeling. This review presents the main molecular mechanisms involved in the pathobiology of PAH, discusses the new molecular compounds currently being developed for the medical treatment of PAH and assesses their potential future role in the therapeutic algorithms of PAH.

Pulmonary Vascular Remodeling in Pulmonary Hypertension

Pulmonary vascular remodeling is the critical structural alteration and pathological feature in pulmonary hypertension (PH) and involves changes in the intima, media and adventitia. Pulmonary vascular remodeling consists of the proliferation and phenotypic transformation of pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) of the middle membranous pulmonary artery, as well as complex interactions involving external layer pulmonary artery fibroblasts (PAFs) and extracellular matrix (ECM). Inflammatory mechanisms, apoptosis and other factors in the vascular wall are influenced by different mechanisms that likely act in concert to drive disease progression. This article reviews these pathological changes and highlights some pathogenetic mechanisms involved in the remodeling process.

In vivo evaluation of the effect of sickle cell hemoglobin S, C and therapeutic transfusion on erythrocyte metabolism and cardiorenal dysfunction

Despite a wealth of exploratory plasma metabolomics studies in sickle cell disease (SCD), no study to date has evaluate a large and well phenotyped cohort to compare the primary erythrocyte metabolome of hemoglobin SS, SC and transfused AA red blood cells (RBCs) in vivo . The current study evaluates the RBC metabolome of 587 subjects with sickle cell sickle cell disease (SCD) from the WALK-PHaSST clinical cohort. The set includes hemoglobin SS, hemoglobin SC SCD patients, with variable levels of HbA related to RBC transfusion events, and HbF related to hydroxyurea therapy. Here we explore the modulating effects of genotype, age, sex, severity of hemolysis, and hydroxyurea and transfusion therapy on sickle RBC metabolism. Data - collated in an online portal - show that the Hb SS genotype is associated with significant alterations of RBC acylcarnitines, pyruvate, sphingosine 1-phosphate, creatinine, kynurenine and urate metabolism. Surprisingly, the RBC metabolism of SC RBCs is dramatically different from SS, with all glycolytic intermediates significantly elevated in SS RBCs, with the exception of pyruvate. This result suggests a metabolic blockade at the ATP-generating phosphoenolpyruvate to pyruvate step of glycolysis, which is catalyzed by redox-sensitive pyruvate kinase. Increasing in vivo concentrations of HbA improved glycolytic flux and normalized the HbS erythrocyte metabolome. An unexpectedly limited metabolic effect of hydroxyurea and HbF was observed, possibly related to the modest induction of HbF in this cohort. The metabolic signature of HbS RBCs correlated with the degree of steady state hemolytic anemia, cardiovascular and renal dysfunction and mortality.

Key points

In vivo dysregulation of RBC metabolism by HbS is evaluated by metabolic profiling of 587 patients with variable HbA, HbC and HbF levels;RBC acyl-carnitines, urate, pyruvate metabolism, S1P, kynurenine relate to hemolysis and cardiorenal dysfunction, respond to transfusion.

Mitochondrial dynamics in vascular remodeling and target-organ damage

Vascular remodeling is the pathological basis for the development of many cardiovascular diseases. The mechanisms underlying endothelial cell dysfunction, smooth muscle cell phenotypic switching, fibroblast activation, and inflammatory macrophage differentiation during vascular remodeling remain elusive. Mitochondria are highly dynamic organelles. Recent studies showed that mitochondrial fusion and fission play crucial roles in vascular remodeling and that the delicate balance of fusion-fission may be more important than individual processes. In addition, vascular remodeling may also lead to target-organ damage by interfering with the blood supply to major body organs such as the heart, brain, and kidney. The protective effect of mitochondrial dynamics modulators on target-organs has been demonstrated in numerous studies, but whether they can be used for the treatment of related cardiovascular diseases needs to be verified in future clinical studies. Herein, we summarize recent advances regarding mitochondrial dynamics in multiple cells involved in vascular remodeling and associated target-organ damage.

Mitochondrial Dysfunction in Pulmonary Hypertension

Pulmonary hypertension (PH) is a multi-etiological condition with a similar hemodynamic clinical sign and end result of right heart failure. Although its causes vary, a similar link across all the classifications is the presence of mitochondrial dysfunction. Mitochondria, as the powerhouse of the cells, hold a number of vital roles in maintaining normal cellular homeostasis, including the pulmonary vascular cells. As such, any disturbance in the normal functions of mitochondria could lead to major pathological consequences. The Warburg effect has been established as a major finding in PH conditions, but other mitochondria-related metabolic and oxidative stress factors have also been reported, making important contributions to the progression of pulmonary vascular remodeling that is commonly found in PH pathophysiology. In this review, we will discuss the role of the mitochondria in maintaining a normal vasculature, how it could be altered during pulmonary vascular remodeling, and the therapeutic options available that can treat its dysfunction.

Shikonin improves pulmonary vascular remodeling in monocrotaline‑induced pulmonary arterial hypertension via regulation of PKM2

Pulmonary arterial hypertension (PAH), a fatal disease with an insidious onset and rapid progression, shows characteristics such as increases in pulmonary circulatory resistance and pulmonary arterial pressure, and progressive right heart failure. Shikonin can reduce right ventricular systolic pressure in chronically hypoxic mice. However, the mechanisms underlying the protective effect of shikonin against PAH pathogenesis have only been sporadically identified. The present study evaluated whether inhibiting the expression of pyruvate kinase M2 (PKM2) contributed to the improvement of pulmonary vascular remodeling in PAH rats induced by monocrotaline (MCT) treatment. Hemodynamic parameters were assessed using echocardiography and right ventricular catheterization. Right ventricular hypertrophy index analysis and hematoxylin and eosin staining were used to evaluate the degree of pulmonary vascular and right heart remodeling. Moreover, PKM2, p‑PKM2, ERK, p‑ERK, glucose transporter 1 (GLUT1), lactate dehydrogenase A (LDHA) protein expression levels were semi‑quantified using western blotting. The expression and distribution of PKM2 were assessed using immunofluorescence microscopy. The present study demonstrated that MCT treatment caused pulmonary arterial hypertension and pulmonary vascular remodeling in experimental rats. Shikonin improved hemodynamics and pulmonary vascular remodeling in MCT‑induced PAH rats, decreased aerobic glycolysis and downregulated PKM2, p‑PKM2, p‑ERK, GLUT 1 and LDHA protein expression levels. Shikonin improved experimental pulmonary arterial hypertension hemodynamics and pulmonary vascular remodeling at least partly through the inhibition of PKM2 and the resultant suppression of aerobic glycolysis. These results provide a novel understanding of possible new treatment targets for PAH.