Regulation of endothelial intracellular adenosine via adenosine kinase epigenetically modulates vascular inflammation

Immune pathogenic response landscape of acute posterior multifocal placoid pigment epitheliopathy revealed by scRNA sequencing

Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is an exceptionally rare inflammatory disorder affecting choroid and retinal pigment epithelial (RPE) cells. Although recent studies suggest an immune-driven nature, the underlying etiology of APMPPE remains elusive. In this study, we conducted a comprehensive investigation on the peripheral blood mononuclear cells (PBMCs) profile of an APMPPE patient using single-cell RNA sequencing. Our analysis revealed striking transcriptional alterations in monocytes within the PBMCs, identifying five distinct subpopulations: S100A12, CD16, pro-inflammatory, megakaryocyte-like, and NK-like monocyte subsets. Employing pseudotime inference, we observed a shift in APMPPE monocytes towards differentiation into inflammation-associated pro-inflammatory monocytes and a CD16 monocyte trajectory. Furthermore, we identified IFITM3 as a key player in the immune response driving the pathogenesis of APMPPE. Notably, two disease-relevant subgroups of monocytes, pro-inflammatory and CD16 monocytes, were implicated in APMPPE. CD16 monocytes, in particular, were involved in melanogenesis, suggesting that the abnormal expression of melanin in monocytes might result from autoimmune responses against pigment-enriched RPE cells. This study provided a comprehensive view of immune landscape in APMPPE, shedding light on the previously unrecognized contributions of pro-inflammatory and CD16 monocytes to this autoimmune condition.

Metabolites and metabolism in vascular calcification: links between adenosine signaling and the methionine cycle

The global population of individuals with cardiovascular disease is expanding, and a key risk factor for major adverse cardiovascular events is vascular calcification. The pathogenesis of cardiovascular calcification is complex and multifaceted, with external cues driving epigenetic, transcriptional, and metabolic changes that promote vascular calcification. This review provides an overview of some of the lesser understood molecular processes involved in vascular calcification and discusses the links between calcification pathogenesis and aspects of adenosine signaling and the methionine pathway; the latter of which salvages the essential amino acid methionine, but also provides the substrate critical for methylation, a modification that regulates the function and activity of DNA and proteins. We explore the complex and dynamic nature of osteogenic reprogramming underlying intimal atherosclerotic calcification and medial arterial calcification (MAC). Atherosclerotic calcification is more widely studied; however, emerging studies now show that MAC is a significant pathology independent from atherosclerosis. Furthermore, we emphasize metabolite and metabolic-modulating factors that influence vascular calcification pathogenesis. Although the contributions of these mechanisms are more well-define in relation to atherosclerotic intimal calcification, understanding these pathways may provide crucial mechanistic insights into MAC and inform future therapeutic approaches. Herein, we highlight the significance of adenosine and methyltransferase pathways as key regulators of vascular calcification pathogenesis.

Anti-inflammation mechanisms of a homogeneous polysaccharide from Phyllanthus emblica L. on DSS induced colitis mice via the gut microbiota and metabolites alteration

Phyllanthus emblica L. offers promising therapeutic potential for inflammatory diseases. This study revealed the molecular structure of a homogeneous polysaccharide purified from Phyllanthus emblica L. (PEP-1) and evaluated its anti-inflammatory effects on ulcerative colitis (UC) in mice. In the in vivo experiment, administered in varying dosages to dextran sulfate sodium (DSS)-induced UC models, PEP-1 significantly alleviated colonic symptoms, histological damages and reshaped the gut microbiota. Notably, it adjusted the Firmicutes/Bacteroidetes ratio and reduced pro-inflammatory species, closely aligning with shifts in the fecal metabolites and metabolic pathways such as the metabolism of pyrimidine, beta-alanine, and purine. These findings underscore the potential of PEP-1 as a therapeutic agent for UC, providing insights into the mechanisms through gut microbiota and metabolic modulation.

Adenosine kinase inhibition protects mice from abdominal aortic aneurysm via epigenetic modulation of VSMC inflammation

AIMS

Abdominal aortic aneurysm (AAA) is a common, serious vascular disease with no effective pharmacological treatment. The nucleoside adenosine plays an important role in modulating vascular homeostasis, which prompted us to determine whether adenosine kinase (ADK), an adenosine metabolizing enzyme, modulates AAA formation via control of the intracellular adenosine level, and to investigate the underlying mechanisms.

METHODS AND RESULTS

We used a combination of genetic and pharmacological approaches in murine models of AAA induced by calcium chloride (CaCl2) application or angiotensin II (Ang II) infusion to study the role of ADK in the development of AAA. In vitro functional assays were performed by knocking down ADK with adenovirus-short hairpin RNA in human vascular smooth muscle cells (VSMCs), and the molecular mechanisms underlying ADK function were investigated using RNA-sequencing, isotope tracing, and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR). The heterozygous deficiency of ADK protected mice from CaCl2- and Ang II-induced AAA formation. Moreover, specific knockout of ADK in VSMCs prevented Ang II-induced AAA formation, as evidenced by reduced aortic extracellular elastin fragmentation, neovascularization, and aortic inflammation. Mechanistically, ADK knockdown in VSMCs markedly suppressed the expression of inflammatory genes associated with AAA formation, and these effects were independent of adenosine receptors. The metabolic flux and ChIP-qPCR results showed that ADK knockdown in VSMCs decreased S-adenosylmethionine (SAM)-dependent transmethylation, thereby reducing H3K4me3 binding to the promoter regions of the genes that are associated with inflammation, angiogenesis, and extracellular elastin fragmentation. Furthermore, the ADK inhibitor ABT702 protected mice from CaCl2-induced aortic inflammation, extracellular elastin fragmentation, and AAA formation.

CONCLUSION

Our findings reveal a novel role for ADK inhibition in attenuating AAA via epigenetic modulation of key inflammatory genes linked to AAA pathogenesis.

Cytosolic DNA initiates a vicious circle of aging-related endothelial inflammation and mitochondrial dysfunction via STING: the inhibitory effect of Cilostazol

Endothelial senescence, aging-related inflammation, and mitochondrial dysfunction are prominent features of vascular aging and contribute to the development of aging-associated vascular disease. Accumulating evidence indicates that DNA damage occurs in aging vascular cells, especially in endothelial cells (ECs). However, the mechanism of EC senescence has not been completely elucidated, and so far, there is no specific drug in the clinic to treat EC senescence and vascular aging. Here we show that various aging stimuli induce nuclear DNA and mitochondrial damage in ECs, thus facilitating the release of cytoplasmic free DNA (cfDNA), which activates the DNA-sensing adapter protein STING. STING activation led to a senescence-associated secretory phenotype (SASP), thereby releasing pro-aging cytokines and cfDNA to further exacerbate mitochondrial damage and EC senescence, thus forming a vicious circle, all of which can be suppressed by STING knockdown or inhibition. Using next-generation RNA sequencing, we demonstrate that STING activation stimulates, whereas STING inhibition disrupts pathways associated with cell senescence and SASP. In vivo studies unravel that endothelial-specific Sting deficiency alleviates aging-related endothelial inflammation and mitochondrial dysfunction and prevents the development of atherosclerosis in mice. By screening FDA-approved vasoprotective drugs, we identified Cilostazol as a new STING inhibitor that attenuates aging-related endothelial inflammation both in vitro and in vivo. We demonstrated that Cilostazol significantly inhibited STING translocation from the ER to the Golgi apparatus during STING activation by targeting S162 and S243 residues of STING. These results disclose the deleterious effects of a cfDNA-STING-SASP-cfDNA vicious circle on EC senescence and atherogenesis and suggest that the STING pathway is a promising therapeutic target for vascular aging-related diseases. A proposed model illustrates the central role of STING in mediating a vicious circle of cfDNA-STING-SASP-cfDNA to aggravate age-related endothelial inflammation and mitochondrial damage.

Development of a biomarker prediction model for post-trauma multiple organ failure/dysfunction syndrome based on the blood transcriptome

BACKGROUND

Multiple organ failure/dysfunction syndrome (MOF/MODS) is a major cause of mortality and morbidity among severe trauma patients. Current clinical practices entail monitoring physiological measurements and applying clinical score systems to diagnose its onset. Instead, we aimed to develop an early prediction model for MOF outcome evaluated soon after traumatic injury by performing machine learning analysis of genome-wide transcriptome data from blood samples drawn within 24 h of traumatic injury. We then compared its performance to baseline injury severity scores and detection of infections.

METHODS

Buffy coat transcriptome and linked clinical datasets from blunt trauma patients from the Inflammation and the Host Response to Injury Study ("Glue Grant") multi-center cohort were used. According to the inclusion/exclusion criteria, 141 adult (age ≥ 16 years old) blunt trauma patients (excluding penetrating) with early buffy coat (≤ 24 h since trauma injury) samples were analyzed, with 58 MOF-cases and 83 non-cases. We applied the Least Absolute Shrinkage and Selection Operator (LASSO) and eXtreme Gradient Boosting (XGBoost) algorithms to select features and develop models for MOF early outcome prediction.

RESULTS

The LASSO model included 18 transcripts (AUROC [95% CI]: 0.938 [0.890-0.987] (training) and 0.833 [0.699-0.967] (test)), and the XGBoost model included 41 transcripts (0.999 [0.997-1.000] (training) and 0.907 [0.816-0.998] (test)). There were 16 overlapping transcripts comparing the two panels (0.935 [0.884-0.985] (training) and 0.836 [0.703-0.968] (test)). The biomarker models notably outperformed models based on injury severity scores and sex, which we found to be significantly associated with MOF (APACHEII + sex-0.649 [0.537-0.762] (training) and 0.493 [0.301-0.685] (test); ISS + sex-0.630 [0.516-0.744] (training) and 0.482 [0.293-0.670] (test); NISS + sex-0.651 [0.540-0.763] (training) and 0.525 [0.335-0.714] (test)).

CONCLUSIONS

The accurate assessment of MOF from blood samples immediately after trauma is expected to aid in improving clinical decision-making and may contribute to reduced morbidity, mortality and healthcare costs. Moreover, understanding the molecular mechanisms involving the transcripts identified as important for MOF prediction may eventually aid in developing novel interventions.

Low Calcium-High Magnesium Krebs-Henseleit Solution Combined with Adenosine and Lidocaine Improved Rat Aortic Function and Structure Following Cold Preservation

Background and objectives: The main problem of vascular preservation is the maintenance of vessel graft quality and function following extended storage. Conventional preservation solutions such as histidine-tryptophan-ketoglutarate (HTK) solution, Phosphate-Buffer Solution (PBS), or sodium chloride 0.9% has been shown to be inadequate in preserving vascular physiological function after 3 days of cold storage. This study aimed to evaluate whether adenosine and lidocaine (AL) in a modified Krebs-Henseleit (KH) solution can preserve the function and histological structure of rat aortic rings after 6 days. Materials and Methods: Thirty-five aortic rings from male Wistar rats (200-300 g) were harvested and immediately immersed in one of the assigned cold preservation solutions: standard KH, modified KH (mod KH) with lower calcium (Ca2+) and higher magnesium content (Mg2+) with or without adenosine and lidocaine (mod KH-AL), and modified KH with AL, insulin, and melatonin (Mod KH-ALMI). The contraction and relaxation function of the aortic rings were examined using an isometric force transducer after 6 days of cold preservation. Hematoxylin and eosin staining were used to analyze the rings' histological structure. Results: Vascular contraction and relaxation functions were severely affected after a 6-day cold storage period in standard KH. Modifying the KH solution by reducing the Ca2+ and increasing the Mg2+ levels greatly recovered the vessel functions. The addition of AL or ALMI to the modified KH did not further recover vascular contractility. However, only the addition of AL to the modified KH increased the ACh-induced relaxation at 6 days when compared to the conventional KH, suggesting that endothelium preservation is improved. From histological analysis, it was found that the addition of AL but not ALMI further improved the endothelial lining and the structure of the elastic membrane layers of the preserved vessels after 6 days of cold preservation. Conclusions: The addition of AL to low calcium-high magnesium KH solution significantly enhanced endothelial preservation and improved endothelial-induced relaxation of preserved vessels after 6 days of cold storage.

Hyperibone J exerts antidepressant effects by targeting ADK to inhibit microglial P2X7R/TLR4-mediated neuroinflammation

INTRODUCTION

The antidepressant properties of Hypericum species are known. Hyperibone J, a principal component found in the flowers of Hypericum bellum, exhibited in vitro anti-inflammatory effects. However, the antidepressant effects and mechanisms of Hyperibone J remain to be elucidated. Adenosine kinase (ADK) is upregulated in epilepsy and depression and has been implicated in promoting neuroinflammation.

OBJECTIVES

This study aimed to explore the impact of Hyperibone J on neuroinflammation-mediated depression and the mechanism underlying this impact.

METHODS

This study employed acute and chronic in vivo depression models and an in vitro LPS-induced depression model using BV-2 microglia. The in vivo antidepressant efficacy of Hyperibone J was assessed through behavioral assays. Techniques such as RNA-seq, western blot, qPCR and ELISA were utilized to elucidate the direct target and mechanism of action of Hyperibone J.

RESULTS

Compared with the model group, depression-like behaviors were significantly alleviated in the Hyperibone J group. Furthermore, Hyperibone J mitigated hippocampal neuroinflammation and neuronal damage. RNA-seq suggested that Hyperibone J predominantly influenced inflammation-related pathways. In vitro experiments revealed that Hyperibone J reversed the LPS-induced overexpression and release of inflammatory factors. Network pharmacology and various molecular biology experiments revealed that the potential binding of Hyperibone J at the ASN-312 site of ADK diminished the stability and protein expression of ADK. Mechanistic studies revealed that Hyperibone J attenuated the ADK/ATP/P2X7R/Caspase-1-mediated maturation and release of IL-1β. The study also revealed a significant correlation between Tlr4 expression and depression-like behaviors in mice. Hyperibone J downregulated ADK, inhibiting Tlr4 transcription, which in turn reduced the phosphorylation of NF-κB and the subsequent transcription of Nlrp3, Il-1b, Tnf, and Il-6.

CONCLUSION

Hyperibone J exerted antineuroinflammatory and antidepressant effects by binding to ADK in microglia, reducing its expression and thereby inhibiting the ATP/P2X7R/Caspase-1 and TLR4/NF-κB pathways. This study provides experimental evidence for the therapeutic potential of Hypericum bellum.

Novel homozygous ADK out-of-frame deletion causes adenosine kinase deficiency with rare phenotypes of sepsis, metabolites disruption and neutrophil dysfunction

Adenosine kinase deficiency (OMIM #614300) is a type of inborn errors of metabolism with multiorgan symptoms primarily neurological disorders, hepatic impairment, global developmental delay, and mild dysmorphism. The genetic causes of adenosine kinase deficiency are homozygous or compound heterozygous loss-of-function variants of ADK. To date, fewer than 25 cases of adenosine kinase deficiency have been reported worldwide and none have been reported in China. In this research, trio whole-exome sequencing (Trio-WES) identified a novel homozygous ADK (NM_001123.4) out-of-frame deletion, c.518_519delCA (p.Thr173Serfs*15), in a Chinese patient with rare phenotypes of sepsis, metabolites disruption and neutrophil dysfunction. This variant was dysfunctional, with marked reduction of ADK level in both the patient's peripheral blood and cells transfected with the corresponding variant. Additionally, metabolomics detected by high-throughput mass spectrometry showed disturbances in the methionine (Met) and energy pathway. RNA sequencing (RNA-seq) of the patient's peripheral blood suggested a defective anti-inflammatory response characterized by impaired neutrophil activation, migration, and degranulation, which might be the primary cause for the sepsis. To our knowledge, we identified the first Chinese patient of adenosine kinase deficiency with a novel homozygous out-of-frame deletion in ADK causing multiorgan disorders, metabolites disruption, rare phenotypes of sepsis, and neutrophil dysfunction. Our findings broaden the genetic spectrum and pathogenic mechanisms of adenosine kinase deficiency.

Diabetes and the fabkin complex: A dual-edged sword

The Fabkin complex, composed of FABP4, ADK, and NDPKs, emerges as a novel regulator of insulin-producing beta cells, offering promising prospects for diabetes treatment. Our approach, which combines literature review and database analysis, sets the stage for future research. These findings hold significant implications for both diabetes treatment and research, as they present potential therapeutic targets for personalized treatment, leading to enhanced patient outcomes and a deeper comprehension of the disease. The multifaceted role of the Fabkin complex in glucose metabolism, insulin resistance, anti-inflammation, beta cell proliferation, and vascular function underscores its therapeutic potential, reshaping diabetes management and propelling advancements in the field.

Edgeworthia gardneri (Wall.) Meisn. Ethanolic Extract Attenuates Endothelial Activation and Alleviates Cardiac Ischemia-Reperfusion Injury

Endothelial pro-inflammatory activation is pivotal in cardiac ischemia-reperfusion (I/R) injury pathophysiology. The dried flower bud of Edgeworthia gardneri (Wall.) Meisn. (EG) is a commonly utilized traditional Tibetan medicine. However, its role in regulating endothelium activation and cardiac I/R injury has not been investigated. Herein, we showed that the administration of EG ethanolic extract exhibited a potent therapeutic efficacy in ameliorating cardiac endothelial inflammation (p < 0.05) and thereby protecting against myocardial I/R injury in rats (p < 0.001). In line with the in vivo findings, the EG extract suppressed endothelial pro-inflammatory activation in vitro by downregulating the expression of pro-inflammatory mediators (p < 0.05) and diminishing monocytes' firm adhesion to endothelial cells (ECs) (p < 0.01). Mechanistically, we showed that EG extract inhibited the nuclear factor kappa-B (NF-κB), c-Jun N-terminal kinase (JNK), extracellular regulated protein kinase (ERK), and p38 mitogen-activated protein kinase (MAPK) signaling pathways to attenuate EC-mediated inflammation (p < 0.05). Collectively, for the first time, this study demonstrated the therapeutic potential of EG ethanolic extract in alleviating I/R-induced inflammation and the resulting cardiac injury through its inhibitory role in regulating endothelium activation.

Targeting adenosine A2A receptors for early intervention of retinopathy of prematurity

Retinopathy of prematurity (ROP) continues to pose a significant threat to the vision of numerous children worldwide, primarily owing to the increased survival rates of premature infants. The pathologies of ROP are mainly linked to impaired vascularization as a result of hyperoxia, leading to subsequent neovascularization. Existing treatments, including anti-vascular endothelial growth factor (VEGF) therapies, have thus far been limited to addressing pathological angiogenesis at advanced ROP stages, inevitably leading to adverse side effects. Intervention to promote physiological angiogenesis during the initial stages could hold the potential to prevent ROP. Adenosine A2A receptors (A2AR) have been identified in various ocular cell types, exhibiting distinct densities and functionally intricate connections with oxygen metabolism. In this review, we discuss experimental evidence that strongly underscores the pivotal role of A2AR in ROP. In particular, A2AR blockade may represent an effective treatment strategy, mitigating retinal vascular loss by reversing hyperoxia-mediated cellular proliferation inhibition and curtailing hypoxia-mediated neovascularization in oxygen-induced retinopathy (OIR). These effects stem from the interplay of endothelium, neuronal and glial cells, and novel molecular pathways (notably promoting TGF-β signaling) at the hyperoxia phase. We propose that pharmacological targeting of A2AR signaling may confer an early intervention for ROP with distinct therapeutic benefits and mechanisms than the anti-VEGF therapy.

Epigenetic regulation in epilepsy: A novel mechanism and therapeutic strategy for epilepsy

Epilepsy is a common neurological disorder characterized by recurrent seizures with excessive and abnormal neuronal discharges. Epileptogenesis is usually involved in neuropathological processes such as ion channel dysfunction, neuronal injury, inflammatory response, synaptic plasticity, gliocyte proliferation and mossy fiber sprouting, currently the pathogenesis of epilepsy is not yet completely understood. A growing body of studies have shown that epigenetic regulation, such as histone modifications, DNA methylation, noncoding RNAs (ncRNAs), N6-methyladenosine (m6A) and restrictive element-1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) are also involved in epilepsy. Through epigenetic studies, we found that the synaptic dysfunction, nerve damage, cognitive dysfunction and brain development abnormalities are affected by epigenetic regulation of epilepsy-related genes in patients with epilepsy. However, the functional roles of epigenetics in pathogenesis and treatment of epilepsy are still to be explored. Therefore, profiling the array of genes that are epigenetically dysregulated in epileptogenesis is likely to advance our understanding of the mechanisms underlying the pathophysiology of epilepsy and may for the amelioration of these serious human conditions provide novel insight into therapeutic strategies and diagnostic biomarkers for epilepsy to improve serious human condition.

Roles of immune dysregulation in MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide. Its occurrence and progression involve the process from simple hepatic steatosis to metabolic dysfunction associated steatohepatitis (MASH), which could develop into advanced liver fibrosis, cirrhosis, or hepatocellular carcinoma (HCC). Growing evidences support that the pathogenesis and progression of MASLD are closely related to immune system dysfunction. This review aims to summarize the association of MASLD with immune disorders and the prospect of using immunotherapy for MASLD.

Developmental and foliation changes due to dysregulation of adenosine kinase in the cerebellum

Adenosine kinase (ADK), the major adenosine-metabolizing enzyme, plays a key role in brain development and disease. In humans, mutations in the Adk gene have been linked to developmental delay, stunted growth, and intellectual disability. To better understand the role of ADK in brain development, it is important to dissect the specific roles of the two isoforms of the enzyme expressed in the cytoplasm (ADK-S) and cell nucleus (ADK-L). We, therefore, studied brain development in Adk-tg transgenic mice, which only express ADK-S in the absence of ADK-L throughout development. In the mutant animals, we found a reduction in the overall brain, body size, and weight during fetal and postnatal development. As a major developmental abnormality, we found a profound change in the foliation pattern of the cerebellum. Strikingly, our results indicated aberrant Purkinje cells arborization at P9 and accelerated cell death at P6 and P9. We found defects in cerebellar cell proliferation and migration using a bromodeoxyuridine (BrdU)-based cell proliferation assay at postnatal day 7. Our data demonstrate that dysregulation of ADK expression during brain development profoundly affects brain growth and differentiation.

Accumulation of endogenous adenosine improves cardiomyocyte metabolism via epigenetic reprogramming in an ischemia-reperfusion model

Adenosine kinase (ADK) plays the major role in cardiac adenosine metabolism, so that inhibition of ADK increases myocardial adenosine levels. While the cardioprotective actions of extracellular adenosine against ischemia/reperfusion (I/R) are well-established, the role of cellular adenosine in protection against I/R remains unknown. Here we investigated the role of cellular adenosine in epigenetic regulation on cardiomyocyte gene expression, glucose metabolism and tolerance to I/R. Evans blue/TTC staining and echocardiography were used to assess the extent of I/R injury in mice. Glucose metabolism was evaluated by positron emission tomography and computed tomography (PET/CT). Methylated DNA immunoprecipitation (MeDIP) and bisulfite sequencing PCR (BSP) were used to evaluate DNA methylation. Lentiviral/adenovirus transduction was used to overexpress DNMT1, and the OSI-906 was administered to inhibit IGF-1. Cardiomyocyte-specific ADK/IGF-1-knockout mice were used for mechanistic experiments.Cardiomyocyte-specific ADK knockout enhanced glucose metabolism and ameliorated myocardial I/R injury in vivo. Mechanistically, ADK deletion caused cellular adenosine accumulation, decreased DNA methyltransferase 1 (DNMT1) expression and caused hypomethylation of multiple metabolic genes, including insulin growth factor 1 (IGF-1). DNMT1 overexpression abrogated these beneficial effects by enhancing apoptosis and decreasing IGF-1 expression. Inhibition of IGF-1 signaling with OSI-906 or genetic knocking down of IGF-1 also abrogated the cardioprotective effects of ADK knockout, revealing the therapeutic potential of increasing IGF-1 expression in attenuating myocardial I/R injury. In conclusion, the present study demonstrated that cardiomyocyte ADK deletion ameliorates myocardial I/R injury via epigenetic upregulation of IGF-1 expression via the cardiomyocyte adenosine/DNMT1/IGF-1 axis.

Multi-ancestry genome-wide study identifies effector genes and druggable pathways for coronary artery calcification

Coronary artery calcification (CAC), a measure of subclinical atherosclerosis, predicts future symptomatic coronary artery disease (CAD). Identifying genetic risk factors for CAC may point to new therapeutic avenues for prevention. Currently, there are only four known risk loci for CAC identified from genome-wide association studies (GWAS) in the general population. Here we conducted the largest multi-ancestry GWAS meta-analysis of CAC to date, which comprised 26,909 individuals of European ancestry and 8,867 individuals of African ancestry. We identified 11 independent risk loci, of which eight were new for CAC and five had not been reported for CAD. These new CAC loci are related to bone mineralization, phosphate catabolism and hormone metabolic pathways. Several new loci harbor candidate causal genes supported by multiple lines of functional evidence and are regulators of smooth muscle cell-mediated calcification ex vivo and in vitro. Together, these findings help refine the genetic architecture of CAC and extend our understanding of the biological and potential druggable pathways underlying CAC.

Skimmin ameliorates cardiac function via the regulation of M2 macrophages in a myocardial infarction mouse model

PURPOSE

Myocardial infarction (MI) is a coronary artery disorder with several complications, such as inflammation, oxidative stress, and cardiac fibrosis. The current study is aimed to explore the protective effect of skimmin (SKI) on impaired heart tissues in MI.

METHODS

A mouse model of MI was induced by ligation of the left anterior descending artery. SKI was intragastric administration for 7 days after MI. Masson staining was then conducted to measure the area of fibrosis in the myocardium. The expression levels of collagen I and collagen III were analyzed using Western blot. The levels of glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and inflammatory factor were also detected. The expression of M1 polarization markers and M2 polarization markers in mice and LPS-induced RAW264.7 cells were detected using RT-qPCR and Western blot, respectively. Finally, the migration and proliferation of vascular smooth muscle cells (VSMCs) in vitro were analyzed using transwell and EDU, respectively.

RESULTS

SKI improved cardiac function and cardiac fibrosis in mice with MI. SKI also decreased collagen I and collagen III expression, and inhibited inflammatory factor TNF-α, IL-1β, and IL-6 levels. SKI decreased the levels of MDA and increased the levels of GSH and SOD. Meanwhile, SKI could promote M2 macrophage polarization in vivo and in vitro. SKI could also repress the migration and proliferation of VSMCs.

CONCLUSIONS

SKI may ameliorate inflammation, oxidative stress, and cardiac fibrosis of MI by promoting M2 polarization.

A2AR-mediated lymphangiogenesis via VEGFR2 signaling prevents salt-sensitive hypertension

AIMS

Excess dietary sodium intake and retention lead to hypertension. Impaired dermal lymphangiogenesis and lymphatic dysfunction-mediated sodium and fluid imbalance are pathological mechanisms. The adenosine A2A receptor (A2AR) is expressed in lymphatic endothelial cells (LECs), while the roles and mechanisms of LEC-A2AR in skin lymphangiogenesis during salt-induced hypertension are not clear.

METHODS AND RESULTS

The expression of LEC-A2AR correlated with lymphatic vessel density in both high-salt diet (HSD)-induced hypertensive mice and hypertensive patients. Lymphatic endothelial cell-specific A2AR knockout mice fed HSD exhibited 17 ± 2% increase in blood pressure and 17 ± 3% increase in Na+ content associated with decreased lymphatic density (-19 ± 2%) compared with HSD-WT mice. A2AR activation by agonist CGS21680 increased lymphatic capillary density and decreased blood pressure in HSD-WT mice. Furthermore, this A2AR agonist activated MSK1 directly to promote VEGFR2 activation and endocytosis independently of VEGF as assessed by phosphoprotein profiling and immunoprecipitation assays in LECs. VEGFR2 kinase activity inhibitor fruquintinib or VEGFR2 knockout in LECs but not VEGF-neutralizing antibody bevacizumab suppressed A2AR activation-mediated decrease in blood pressure. Immunostaining revealed phosphorylated VEGFR2 and MSK1 expression in the LECs were positively correlated with skin lymphatic vessel density and A2AR level in hypertensive patients.

CONCLUSION

The study highlights a novel A2AR-mediated VEGF-independent activation of VEGFR2 signaling in dermal lymphangiogenesis and sodium balance, which might be a potential therapeutic target in salt-sensitive hypertension.

Glycolysis and de novo fatty acid synthesis cooperatively regulate pathological vascular smooth muscle cell phenotypic switching and neointimal hyperplasia

Switching of vascular smooth muscle cells (VSMCs) from a contractile phenotype to a dedifferentiated (proliferative) phenotype contributes to neointima formation, which has been demonstrated to possess a tumor-like nature. Dysregulated glucose and lipid metabolism is recognized as a hallmark of tumors but has not thoroughly been elucidated in neointima formation. Here, we investigated the cooperative role of glycolysis and fatty acid synthesis in vascular injury-induced VSMC dedifferentiation and neointima formation. We found that the expression of hypoxia-inducible factor-1α (HIF-1α) and its target 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), a critical glycolytic enzyme, were induced in the neointimal VSMCs of human stenotic carotid arteries and wire-injured mouse carotid arteries. HIF-1α overexpression led to elevated glycolysis and resulted in a decreased contractile phenotype while promoting VSMC proliferation and activation of the mechanistic target of rapamycin complex 1 (mTORC1). Conversely, silencing Pfkfb3 had the opposite effects. Mechanistic studies demonstrated that glycolysis generates acetyl coenzyme A to fuel de novo fatty acid synthesis and mTORC1 activation. Whole-transcriptome sequencing analysis confirmed the increased expression of PFKFB3 and fatty acid synthetase (FASN) in dedifferentiated VSMCs. More importantly, FASN upregulation was observed in neointimal VSMCs of human stenotic carotid arteries. Finally, interfering with PFKFB3 or FASN suppressed vascular injury-induced mTORC1 activation, VSMC dedifferentiation, and neointima formation. Together, this study demonstrated that PFKFB3-mediated glycolytic reprogramming and FASN-mediated lipid metabolic reprogramming are distinctive features of VSMC phenotypic switching and could be potential therapeutic targets for treating vascular diseases with neointima formation. © 2023 The Pathological Society of Great Britain and Ireland.

Metabolic Reprogramming of Breast Tumor-Educated Macrophages Revealed by NMR Metabolomics

The metabolic crosstalk between tumor cells and tumor-associated macrophages (TAMs) has emerged as a critical contributor to tumor development and progression. In breast cancer (BC), the abundance of immune-suppressive TAMs positively correlates with poor prognosis. However, little is known about how TAMs reprogram their metabolism in the BC microenvironment. In this work, we have assessed the metabolic and phenotypic impact of incubating THP-1-derived macrophages in conditioned media (CM) from two BC cell lines cultured in normoxia/hypoxia: MDA-MB-231 cells (highly metastatic, triple-negative BC), and MCF-7 cells (less aggressive, luminal BC). The resulting tumor-educated macrophages (TEM) displayed prominent differences in their metabolic activity and composition, compared to control cells (M0), as assessed by exo- and endometabolomics. In particular, TEM turned to the utilization of extracellular pyruvate, alanine, and branched chain keto acids (BCKA), while exhibiting alterations in metabolites associated with several intracellular pathways, including polyamines catabolism (MDA-TEM), collagen degradation (mainly MCF-TEM), adenosine accumulation (mainly MDA-TEM) and lipid metabolism. Interestingly, following a second-stage incubation in fresh RPMI medium, TEM still displayed several metabolic differences compared to M0, indicating persistent reprogramming. Overall, this work provided new insights into the metabolic plasticity of TEM, revealing potentially important nutritional exchanges and immunoregulatory metabolites in the BC TME.

Adenosine kinase promotes post-infarction cardiac repair by epigenetically maintaining reparative macrophage phenotype

Pro-inflammatory and reparative macrophages are crucial in clearing necrotic myocardium and promoting cardiac repair after myocardial infarction (MI), respectively. Extracellular adenosine has been demonstrated to modulate macrophage polarization through adenosine receptors. However, the role of intracellular adenosine in macrophage polarization has not been explored and adenosine kinase (ADK) is a major enzyme regulating intracellular adenosine levels. Here, we aimed to elucidate the role of ADK in macrophage polarization and its subsequent impact on MI. We demonstrated that ADK was upregulated in bone marrow-derived macrophages (BMDMs) after IL-4 treatment and was highly expressed in the infarct area at day 7 post-MI, especially in macrophages. Compared with wild-type mice, myeloid-specific Adk knockout mice showed increased infarct size, limited myofibroblast differentiation, reduced collagen deposition and more severe cardiac dysfunction after MI, which was related to impaired reparative macrophage phenotype in MI tissue. We found that ADK deletion or inhibition significantly decreased the expression of reparative genes, such as Arg1, Ym1, Fizz1, and Cd206 in BMDMs after IL-4 treatment. The increased intracellular adenosine due to Adk deletion inhibited transmethylation reactions and decreased the trimethylation of H3K4 in BMDMs after IL-4 treatment. Mechanistically, we demonstrated that Adk deletion suppressed reparative macrophage phenotype through decreased IRF4 expression, which resulted from reduced levels of H3K4me3 on the Irf4 promotor. Together, our study reveals that ADK exerts a protective effect against MI by promoting reparative macrophage polarization through epigenetic mechanisms.

Hepatocyte Adenosine Kinase Promotes Excessive Fat Deposition and Liver Inflammation

BACKGROUND & AIMS

Nonalcoholic fatty liver disease is highly associated with obesity and progresses to nonalcoholic steatohepatitis when the liver develops overt inflammatory damage. While removing adenosine in the purine salvage pathway, adenosine kinase (ADK) regulates methylation reactions. We aimed to study whether hepatocyte ADK functions as an obesogenic gene/enzyme to promote excessive fat deposition and liver inflammation.

METHODS

Liver sections of human subjects were examined for ADK expression using immunohistochemistry. Mice with hepatocyte-specific ADK disruption or overexpression were examined for hepatic fat deposition and inflammation. Liver lipidomics, hepatocyte RNA sequencing (RNA-seq), and single-cell RNA-seq for liver nonparenchymal cells were performed to analyze ADK regulation of hepatocyte metabolic responses and hepatocyte-nonparenchymal cells crosstalk.

RESULTS

Whereas patients with nonalcoholic fatty liver disease had increased hepatic ADK levels, mice with hepatocyte-specific ADK disruption displayed decreased hepatic fat deposition on a chow diet and were protected from diet-induced excessive hepatic fat deposition and inflammation. In contrast, mice with hepatocyte-specific ADK overexpression displayed increased body weight and adiposity and elevated degrees of hepatic steatosis and inflammation compared with control mice. RNA-seq and epigenetic analyses indicated that ADK increased hepatic DNA methylation and decreased hepatic Ppara expression and fatty acid oxidation. Lipidomic and single-cell RNA-seq analyses indicated that ADK-driven hepatocyte factors, due to mitochondrial dysfunction, enhanced macrophage proinflammatory activation in manners involving increased expression of stimulator of interferon genes.

CONCLUSIONS

Hepatocyte ADK functions to promote excessive fat deposition and liver inflammation through suppressing hepatocyte fatty acid oxidation and producing hepatocyte-derived proinflammatory mediators. Therefore, hepatocyte ADK is a therapeutic target for managing obesity and nonalcoholic fatty liver disease.

Cupping alleviates lung injury through the adenosine/A2BAR pathway

Background

Acute lung injury (ALI) is a serious condition. Inflammation plays a crucial role in the pathogenesis of ALI. Cupping, as a part of traditional Chinese medicine, is still a popular complementary and alternative therapy for a variety of ailments including respiratory diseases. However, reliable scientific data about cupping therapy are scarce. Adenosine, a purine nucleoside produced under metabolic stress by the action of extracellular ectonucleotidases (i.e. CD39 and CD73), can attenuate ALI through the A_2BAR receptor. The aim of this study was to investigate the protective effect of cupping in a rat model of ALI and the role of adenosine in it.

Methods

Male adult rats were subjected to ALI by intratracheal LPS instillation (0.3 mg/kg). Immediately after intratracheal LPS instillation, vacuum pressure was applied to a sanitized plastic bell cup on the back of the rat by suction for 10 min. Pulmonary injury and inflammation were assessed at 4 h after LPS challenge. The role of adenosine and A_2BAR in cupping's protection after LPS instillation were evaluated.

Results

Cupping alleviated LPS-induced lung injury, reduced inflammation and inhibited NF-kB activation in rats. Cupping upregulated CD39 and CD73 mRNA expression of the skin tissue at the cupping site and increased circulating levels of adenosine. Administration of PSB1115, a specific adenosine A_2BAR receptor antagonist, abolished cupping's beneficial effects in LPS-induced ALI.

Conclusions

Cupping attenuates lung inflammation and injury through the adenosine/A_2BAR pathway. The current study provides evidence-based information about cupping therapy in ALI.

Gene-dosage effect of Pfkfb3 on monocyte/macrophage biology in atherosclerosis

BACKGROUND AND PURPOSE

Macrophage-rich atherosclerotic arteries are highly active in glycolysis. PFKFB3, a key glycolytic enzyme, has emerged as a potential therapeutic target in atherosclerosis. Small-molecule inhibitors of PFKFB3, such as 3PO and PFK158, have demonstrated efficacy in hampering atherogenesis in preclinical models. However, genetic studies elucidating the role of Pfkfb3 in atherogenesis need to be conducted to validate pharmacological findings and to unveil potential pharmacological side effects.

EXPERIMENTAL APPROACH

Apoe-/- mice with global heterozygous or myeloid cell-specific Pfkfb3 deficiency were fed a Western diet (WD), after which atherosclerosis development was determined. Monocyte subsets in atherosclerotic mice and patients were examined by flow cytometry. Monocyte infiltration was assayed by a Ly6Chi monocyte-specific latex labelling procedure. In situ efferocytosis was assessed on mouse aortic root sections. Additionally, metabolic status, macrophage motility, efferocytosis, and involved mechanisms were analysed in peritoneal macrophages.

KEY RESULTS

Global heterozygous or myeloid cell-specific Pfkfb3 deficiency reduced atherogenesis in Apoe-/- mice. Mechanistic studies showed that PFKFB3 controlled the proliferation and infiltration of proinflammatory monocytes. Moreover, PFKFB3 expression was associated with inflammatory monocyte expansion in patients with atherosclerotic coronary artery disease. Surprisingly, homozygous loss of Pfkfb3 impaired macrophage efferocytosis and exacerbated atherosclerosis in Apoe-/- mice. Mechanistically, PFKFB3-driven glycolysis was shown to be essential for actin polymerization, thus aiding the efferocytotic function of macrophages.

CONCLUSION AND IMPLICATIONS

Collectively, these findings suggest the existence of a double-edged sword effect of myeloid PFKFB3 on the pathogenesis of atherosclerosis and highlight the need for caution in developing anti-atherosclerotic strategies that target PFKFB3.

Potential biomarkers for inflammatory response in acute lung injury

Acute lung injury (ALI) is a severe respiratory disorder occurring in critical care medicine, with high rates of mortality and morbidity. This study aims to screen the potential biomarkers for ALI. Microarray data of lung tissues from lung-specific geranylgeranyl pyrophosphate synthase large subunit 1 knockout and wild-type mice treated with lipopolysaccharide were downloaded. Differentially expressed genes (DEGs) between ALI and wild-type mice were screened. Functional analysis and the protein-protein interaction (PPI) modules were analyzed. Finally, a miRNA-transcription factor (TF)-target regulation network was constructed. Totally, 421 DEGs between ALI and wild-type mice were identified. The upregulated DEGs were mainly enriched in the peroxisome proliferator-activated receptor signaling pathway, and fatty acid metabolic process, while downregulated DEGs were related to cytokine-cytokine receptor interaction and regulation of cytokine production. Cxcl5, Cxcl9, Ccr5, and Cxcr4 were key nodes in the PPI network. In addition, three miRNAs (miR505, miR23A, and miR23B) and three TFs (PU1, CEBPA, and CEBPB) were key molecules in the miRNA-TF-target network. Nine genes including ADRA2A, P2RY12, ADORA1, CXCR1, and CXCR4 were predicted as potential druggable genes. As a conclusion, ADRA2A, P2RY12, ADORA1, CXCL5, CXCL9, CXCR1, and CXCR4 might be novel markers and potential druggable genes in ALI by regulating inflammatory response.

ATP and Adenosine Metabolism in Cancer: Exploitation for Therapeutic Gain

Adenosine is an evolutionary ancient metabolic regulator linking energy state to physiologic processes, including immunomodulation and cell proliferation. Tumors create an adenosine-rich immunosuppressive microenvironment through the increased release of ATP from dying and stressed cells and its ectoenzymatic conversion into adenosine. Therefore, the adenosine pathway becomes an important therapeutic target to improve the effectiveness of immune therapies. Prior research has focused largely on the two major ectonucleotidases, ectonucleoside triphosphate diphosphohydrolase 1/cluster of differentiation (CD)39 and ecto-5'-nucleotidase/CD73, which catalyze the breakdown of extracellular ATP into adenosine, and on the subsequent activation of different subtypes of adenosine receptors with mixed findings of antitumor and protumor effects. New findings, needed for more effective therapeutic approaches, require consideration of redundant pathways controlling intratumoral adenosine levels, including the alternative NAD-inactivating pathway through the CD38-ectonucleotide pyrophosphatase phosphodiesterase (ENPP)1-CD73 axis, the counteracting ATP-regenerating ectoenzymatic pathway, and cellular adenosine uptake and its phosphorylation by adenosine kinase. This review provides a holistic view of extracellular and intracellular adenosine metabolism as an integrated complex network and summarizes recent data on the underlying mechanisms through which adenosine and its precursors ATP and ADP control cancer immunosurveillance, tumor angiogenesis, lymphangiogenesis, cancer-associated thrombosis, blood flow, and tumor perfusion. Special attention is given to differences and commonalities in the purinome of different cancers, heterogeneity of the tumor microenvironment, subcellular compartmentalization of the adenosine system, and novel roles of purine-converting enzymes as targets for cancer therapy. SIGNIFICANCE STATEMENT: The discovery of the role of adenosine as immune checkpoint regulator in cancer has led to the development of novel therapeutic strategies targeting extracellular adenosine metabolism and signaling in multiple clinical trials and preclinical models. Here we identify major gaps in knowledge that need to be filled to improve the therapeutic gain from agents targeting key components of the adenosine metabolic network and, on this basis, provide a holistic view of the cancer purinome as a complex and integrated network.

Inhibition of S-adenosylhomocysteine hydrolase induces endothelial senescence via hTERT downregulation

BACKGROUND AND AIMS

It has been established that endothelial senescence plays a critical role in the development of atherosclerosis. Elevated S-adenosylhomocysteine (SAH) level induced by inhibition of S-adenosylhomocysteine hydrolase (SAHH) is one of the risk factors of atherosclerosis; however, the interplay between endothelial senescence and inhibition of SAHH is largely unknown.

METHODS

Human umbilical vein endothelial cells (HUVECs) after serial passage were used. SAHH-specific inhibitor adenosine dialdehyde (ADA) and SAHH siRNA treated HUVECs and SAHH^+/-mice were used to investigate the effect of SAHH inhibition on endothelial senescence.

RESULTS

HUVECs exhibited distinct senescence morphology as HUVECs were passaged, together with a decrease in intracellular SAHH expression and an increase in intracellular SAH levels. SAHH inhibition by ADA or SAHH siRNA elevated SA β-gal activity, arrested proliferation, and increased the expression of p16, p21 and p53 in HUVECs and the aortas of mice. In addition, decreased expression of hTERT and reduced occupancy of H3K4me3 over the hTERT promoter region were observed following SAHH inhibition treatment. To further verify the role of hTERT in the endothelial senescence induced by SAHH inhibition, hTERT was overexpressed with a plasmid vector under CMV promoter. hTERT overexpression rescued the senescence phenotypes in endothelial cells induced by SAHH inhibition.

CONCLUSIONS

SAHH inhibition induces endothelial senescence via downregulation of hTERT expression, which is associated with attenuated histone methylation over the hTERT promoter region.

Endothelial cell-targeting, ROS-ultrasensitive drug/siRNA co-delivery nanocomplexes mitigate early-stage neutrophil recruitment for the anti-inflammatory treatment of myocardial ischemia reperfusion injury

Neutrophils serve as a key contributor to the pathophysiology of myocardial ischemia reperfusion injury (MIRI), because the unregulated activation and infiltration of neutrophils lead to overwhelming inflammation in the myocardium to cause tissue damage. Herein, endothelial cell-targeting and  reactive oxygen species (ROS)-ultrasensitive nanocomplexes (NCs) were developed to mediate efficient co-delivery of VCAM-1 siRNA (siVCAM-1) and dexamethasone (DXM), which cooperatively inhibited neutrophil recruitment by impeding neutrophil migration and adhesion. RPPT was first synthesized via crosslinking of PEI 600 with ditellurium followed by modification with PEG and the endothelial cell-targeting peptide cRGD. RPPT was allowed to envelope the DXM-loaded PLGA nanoparticles and condense the siVCAM-1. After systemic administration in rats experiencing MIRI, the cRGD-modified NCs efficiently targeted and entered the inflamed endothelial cells, wherein RPPT was sensitively degraded by over-produced ROS to trigger intracellular siVCAM-1 release and potentiate the VCAM-1 silencing efficiency. As a consequence of the complementary function of DXM and siVCAM-1, the NCs notably mitigated neutrophil infiltration into ischemic myocardium, provoking potent anti-inflammatory efficacy to reduce MIRI and recover cardiac function. The present study offers an effective approach for the controlled co-delivery of siRNA and drug cargoes, and it also highlights the importance of multi-dimensional manipulation of neutrophils in anti-inflammatory treatment. STATEMENT OF SIGNIFICANCE: The unregulated activation and infiltration of neutrophils lead to overwhelming inflammation in the myocardium after myocardial ischemia reperfusion injury (MIRI). Here, endothelial cell-targeting and ROS-ultrasensitive nanocomplexes (NCs), comprised of PLGA NPs decorated with cRGD-poly(ethylene glycol) (PEG)-modified, ditellurium-crosslinked PEI (RPPT), were developed to mediate efficient co-delivery of VCAM-1 siRNA (siVCAM-1) and dexamethasone (DXM). DXM and siVCAM-1 with complementary functions inhibited both the migration and adhesion of neutrophils, efficiently interventing the neutrophil recruitment and interrupting the self-amplified inflammation cascade in the injured myocardium. The molecular design of RPPT renders an effective example for constructing polymeric materials with high ROS sensitivity, and it resolves the critical dilemma related to polycation-mediated siRNA delivery, such as siRNA encapsulation versus release, and transfection efficiency versus toxicity.

Epigenetic Upregulation of H19 and AMPK Inhibition Concurrently Contribute to S-Adenosylhomocysteine Hydrolase Deficiency-Promoted Atherosclerotic Calcification

BACKGROUND

S-adenosylhomocysteine (SAH) is a risk factor of cardiovascular disease; inhibition of SAH hydrolase (SAHH) results in SAH accumulation and induces endothelial dysfunction and atherosclerosis. However, the effect and mechanism of SAHH in atherosclerotic calcification is still unclear. We aimed to explore the role and mechanism of SAHH in atherosclerotic calcification.

METHODS

The relationship between SAHH and atherosclerotic calcification was investigated in patients with coronary atherosclerotic calcification. Different in vivo genetic models were used to examine the effect of SAHH deficiency on atherosclerotic calcification. Human aortic and murine vascular smooth muscle cells (VSMCs) were cultured to explore the underlying mechanism of SAHH on osteoblastic differentiation of VSMCs.

RESULTS

The expression and activity of SAHH were decreased in calcified human coronary arteries and inversely associated with coronary atherosclerotic calcification severity, whereas plasma SAH and total homocysteine levels were positively associated with coronary atherosclerotic calcification severity. Heterozygote knockout of SAHH promoted atherosclerotic calcification. Specifically, VSMC-deficient but not endothelial cell-deficient or macrophage-deficient SAHH promoted atherosclerotic calcification. Mechanistically, SAHH deficiency accumulated SAH levels and induced H19-mediated Runx2 (runt-related transcription factor 2)-dependent osteoblastic differentiation of VSMCs by inhibiting DNMT3b (DNA methyltransferase 3 beta) and leading to hypomethylation of the H19 promoter. On the other hand, SAHH deficiency resulted in lower intracellular levels of adenosine and reduced AMPK (AMP-activated protein kinase) activation. Adenosine supplementation activated AMPK and abolished SAHH deficiency-induced expression of H19 and Runx2 and osteoblastic differentiation of VSMCs. Finally, AMPK activation by adenosine inhibited H19 expression by inducing Sirt1-mediated histone H3 hypoacetylation and DNMT3b-mediated hypermethylation of the H19 promoter in SAHH deficiency VSMCs.

CONCLUSIONS

We have confirmed a novel correlation between SAHH deficiency and atherosclerotic calcification and clarified a new mechanism that epigenetic upregulation of H19 and AMPK inhibition concurrently contribute to SAHH deficiency-promoted Runx2-dependent atherosclerotic calcification.

Glycolysis inhibition ameliorates brain injury after ischemic stroke by promoting the function of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells which are immunosuppressive and glycolytically inactive in inflammatory diseases. However, it is unknown whether MDSCs contribute to ischemic stroke and how glycolysis regulates MDSC function in such a context. Here, we showed that MDSCs arise in the blood of patients at early phase of stroke. Similar results were observed in temporary middle cerebral artery occlusion-induced cerebral ischemic mice. Pharmaceutical exhaustion of MDSCs aggravated, while adoptive transfer of MDSCs rescued the ischemic brain injury. However, the differentiation of MDSCs into immunopotent myeloid cells which coincides with increased glycolysis was observed in the context of ischemic stroke. Mechanistically, the glycolytic product lactate autonomously induces MDSC differentiation through activation of mTORC1, and paracrinely activates Th1 and Th17 cells. Moreover, gene knockout or inhibition of the glycolytic enzyme PFKFB3 increased endogenous MDSCs by blocking their differentiation, and improved ischemic brain injury. Collectively, these results revealed that glycolytic switch decreases the immunosuppressive and neuroprotective role of MDSCs in ischemic stroke and pharmacological targeting MDSCs via glycolysis inhibition constitutes a promising therapeutic strategy for ischemic stroke.

Adenosine Kinase Inhibition Prevents Severe Acute Pancreatitis via Suppressing Inflammation and Acinar Cell Necroptosis

Background: Inflammatory disorder and acinar cell death contribute to the initiation and progression of severe acute pancreatitis (SAP). Adenosine kinase (ADK) has potential effects on both inflammation and cell death. However, the role of ADK in SAP remains to be explored.

Methods: To establish an experimental SAP model, male C57BL/6 mice were intraperitoneally injected with cerulein (50 μg/kg, seven doses at hourly intervals) and LPS (10 mg/kg, at the last cerulein injection). For ADK inhibition, ABT702 (1.5 mg/kg) was intraperitoneally injected 1 h before cerulein treatment. The pancreas and serum were collected and analyzed to determine the severity of pancreatic injury and explore the potential pathophysiological mechanisms. Pancreatic acinar cells (AR42J) were used to explore the in vitro effects of ADK inhibition on cerulein–induced inflammation and necroptotic cell death.

Results: ADK inhibition notably attenuated the severity of SAP, as indicated by the decreased serum amylase (7,416.76 ± 1,457.76 vs. 4,581.89 ± 1,175.04 U/L) and lipase (46.51 ± 11.50 vs. 32.94 ± 11.46 U/L) levels and fewer pancreatic histopathological alterations (histological scores: 6.433 ± 0.60 vs. 3.77 ± 0.70). MOMA-2 and CD11b staining confirmed that ADK inhibition prevented the infiltration of neutrophils and macrophages. The phosphorylation of nuclear factor-κB (NF-κB) was also reduced by ADK inhibition. ADK inhibition markedly limited the necrotic area of the pancreas and prevented the activation of the necroptotic signaling pathway. Endoplasmic reticulum (ER) stress was activated in the pancreas using the SAP model and cerulein–treated AR42J cells whereas ADK inhibition reversed the activation of ER stress both in vivo and in vitro. Moreover, the alleviating effects of ADK inhibition on ER stress, inflammation, and cell necroptosis were eliminated by the adenosine A_2A receptor antagonist.

Conclusion: ADK inhibition reduced inflammation and necroptotic acinar cell death in SAP via the adenosine A_2A receptor/ER stress pathway, suggesting that ADK might be a potential therapeutic target for SAP.

Effects of chronic exposure to environmental levels of tributyltin on the lined seahorse (Hippocampus erectus) liver: Analysis of bioaccumulation, antioxidant defense, and immune gene expression

Tributyltin (TBT), an organotin compound frequently detected in the coastal environments, poses a threat to aquatic organisms. The lined seahorse (Hippocampus erectus) is a vulnerable species found in nearshore water habitats. The mechanisms by which this fish responds to TBT exposure are not yet fully understood. Histological, biochemical, and transcriptional analyses were conducted, and the results showed that 60 days of exposure to 50 and 500 ng/L TBT caused significant tin accumulation and liver damage to seahorses. Antioxidant defenses and immune responses to TBT exposure in the livers of seahorses were further investigated. The enzymatic activity of superoxide dismutase and malondialdehyde content increased, while catalase activity decreased. Transcriptomic analysis revealed that a series of genes involved in the antioxidant defense system were highly induced to protect the hepatic cells from oxidative damage. TBT exposure also resulted in the induction of genes associated with immune and inflammatory processes, representing a stress response to combat the adverse environmental conditions in the exposed seahorses. Furthermore, seahorses showed an increased health risk, according to the elevation of the expression of genes with tumor-promoting effects, when exposed to TBT. These findings contribute to our understanding of the adverse effects of TBT exposure on seahorses, and their potential defense mechanisms.

Caffeine promotes angiogenesis through modulating endothelial mitochondrial dynamics

Caffeine induces multiple vascular effects. In this study we investigated the angiogenic effect of physiological concentrations of caffeine with focus on endothelial cell behaviors (migration and proliferation) during angiogenesis and its mitochondrial and bioenergetic mechanisms. We showed that caffeine (10-50 μM) significantly enhanced angiogenesis in vitro, evidenced by concentration-dependent increases in tube formation, and migration of human umbilical vein endothelial cells (HUVECs) without affecting cell proliferation. Caffeine (50 μM) enhanced endothelial migration via activation of cAMP/PKA/AMPK signaling pathway, which was mimicked by cAMP analog 8-Br-cAMP, and blocked by PKA inhibitor H89, adenylate cyclase inhibitor SQ22536 or AMPK inhibitor compound C. Furthermore, caffeine (50 μM) induced significant mitochondrial shortening through the increased phosphorylation of mitochondrial fission protein dynamin-related protein 1 (Drp1) in HUVECs, which increased its activity to regulate mitochondrial fission. Pharmacological blockade of Drp1 by Mdivi-1 (10 μM) or disturbance of mitochondrial fission by Drp1 silencing markedly suppressed caffeine-induced lamellipodia formation and endothelial cell migration. Moreover, we showed that caffeine-induced mitochondrial fission led to accumulation of more mitochondria in lamellipodia regions and augmentation of mitochondrial energetics, both of which were necessary for cell migration. In a mouse model of hindlimb ischemia, administration of caffeine (0.05% in 200 mL drinking water daily, for 14 days) significantly promoted angiogenesis and perfusion as well as activation of endothelial AMPK signaling in the ischemic hindlimb. Taken together, caffeine induces mitochondrial fission through cAMP/PKA/AMPK signaling pathway. Mitochondrial fission is an integral process in caffeine-induced endothelial cell migration by altering mitochondrial distribution and energetics.

Current Adenosinergic Therapies: What Do Cancer Cells Stand to Gain and Lose?

A key objective in immuno-oncology is to reactivate the dormant immune system and increase tumour immunogenicity. Adenosine is an omnipresent purine that is formed in response to stress stimuli in order to restore physiological balance, mainly via anti-inflammatory, tissue-protective, and anti-nociceptive mechanisms. Adenosine overproduction occurs in all stages of tumorigenesis, from the initial inflammation/local tissue damage to the precancerous niche and the developed tumour, making the adenosinergic pathway an attractive but challenging therapeutic target. Many current efforts in immuno-oncology are focused on restoring immunosurveillance, largely by blocking adenosine-producing enzymes in the tumour microenvironment (TME) and adenosine receptors on immune cells either alone or combined with chemotherapy and/or immunotherapy. However, the effects of adenosinergic immunotherapy are not restricted to immune cells; other cells in the TME including cancer and stromal cells are also affected. Here we summarise recent advancements in the understanding of the tumour adenosinergic system and highlight the impact of current and prospective immunomodulatory therapies on other cell types within the TME, focusing on adenosine receptors in tumour cells. In addition, we evaluate the structure- and context-related limitations of targeting this pathway and highlight avenues that could possibly be exploited in future adenosinergic therapies.

Endothelial AMPKα1/PRKAA1 exacerbates inflammation in HFD-fed mice

BACKGROUND AND PURPOSE

Excess nutrient-induced endothelial cell inflammation is a hallmark in high fat diet (HFD)-induced metabolic syndrome. Pharmacological activation of protein kinase AMP-activated alpha 1(PRKAA1)/5'-Adenosine monophosphate-activated protein kinase alpha1 (AMPKα1) shows its beneficial effects in many studies of cardiometabolic disorders. However, AMPKα1, as a major cellular sensor of energy and nutrients in endothelial cells, has not been studied for its physiological role in excess nutrient-induced endothelial cell (EC) inflammation.

EXPERIMENTAL APPROACH

Wild-type and EC-specific Prkaa1 knockout mice were fed with an HFD. Body weight, fat mass composition, glucose and lipid levels were monitored regularly. Insulin sensitivity was analyzed systemically and in major metabolic organs/tissues. Inflammation status in metabolic organs/tissues were examined with quantitative RT-PCR and flow cytometry. Additionally, metabolic status, inflammation severity and signaling in cultured ECs were assayed with multiple approaches at the molecular level.

KEY RESULTS

EC Prkaa1 deficiency unexpectedly alleviated HFD-induced metabolic syndromes including decreased body weight and fat mass, enhanced glucose clearance and insulin sensitivity, and relieved adipose inflammation and hepatic steatosis. Mechanistically, PRKAA1 knockdown in cultured ECs reduced endothelial glycolysis and fatty acid oxidation, decreased the levels of acetyl-coA, and suppressed transcription of inflammatory molecules mediated by ATP citrate lyase (ACLY) and histone acetyltransferase p300.

CONCLUSIONS AND IMPLICATIONS

This unexpected pro-inflammatory effect of endothelial AMPKα1/PRKAA1 in metabolic context provides additional insight in AMPKα1/PRKAA1 activities, warranting that in-depth study and thoughtful consideration should be applied when AMPKα1/PRKAA1 is used as a therapeutic target in the treatment of metabolic syndrome.

The elegant complexity of mammalian ecto-5'-nucleotidase (CD73)

Purinergic signaling is a fundamental mechanism used by all cells to control their internal activities and interact with the environment. A key component of the purinergic system, the enzyme ecto-5'-nucleotidase (CD73) catalyzes the last step in the extracellular metabolism of ATP to form adenosine. Efforts to harness the therapeutic potential of endogenous adenosine in cancer have culminated in the ongoing clinical development of multiple CD73-targeting antibodies and small-molecule inhibitors. However, recent studies are painting an increasingly complex picture of CD73 mRNA and protein regulation and function in cellular homeostasis, physiological adaptation, and disease development. This review discusses the latest conceptual and methodological advances that are helping to unravel the complexity of this important enzyme that was identified nearly 90 years ago.

Pharmacological Tuning of Adenosine Signal Nuances Underlying Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) roughly represents half of the cardiac failure events in developed countries. The proposed 'systemic microvascular paradigm' has been used to explain HFpHF presentation heterogeneity. The lack of effective treatments with few evidence-based therapeutic recommendations makes HFpEF one of the greatest unmet clinical necessities worldwide. The endogenous levels of the purine nucleoside, adenosine, increase significantly following cardiovascular events. Adenosine exerts cardioprotective, neuromodulatory, and immunosuppressive effects by activating plasma membrane-bound P1 receptors that are widely expressed in the cardiovascular system. Its proven benefits have been demonstrated in preclinical animal tests. Here, we provide a comprehensive and up-to-date critical review about the main therapeutic advantages of tuning adenosine signalling pathways in HFpEF, without discounting their side effects and how these can be seized.

Adenosine Triggers Larval Settlement and Metamorphosis in the Mussel Mytilopsis sallei through the ADK-AMPK-FoxO Pathway

Settlement and metamorphosis of planktonic larvae into benthic adults are critical components of a diverse range of marine invertebrate-mediated processes such as the formation of mussel beds and coral reefs, the recruitment of marine shellfisheries, and the initiation of macrobiofouling. Although larval settlement and metamorphosis induced by natural chemical cues is widespread among marine invertebrates, the mechanisms of action remain poorly understood. Here, we identified that the molecular target of adenosine (an inducer of larval settlement and metamorphosis from conspecific adults in the invasive biofouling mussel Mytilopsis sallei) is adenosine kinase (ADK). The results of transcriptomic analyses, pharmacological assays, temporal and spatial gene expression analyses, and siRNA interference, suggest that ATP-dependent phosphorylation of adenosine catalyzed by ADK activates the downstream AMPK-FoxO signaling pathway, inducing larval settlement and metamorphosis in M. sallei. This study not only reveals the role of the ADK-AMPK-FoxO pathway in larval settlement and metamorphosis of marine invertebrates but it also deepens our understanding of the functions and evolution of adenosine signaling, a process that is widespread in biology and important in medicine.

Adenosine kinase: An epigenetic modulator in development and disease

Adenosine kinase (ADK) is the key regulator of adenosine and catalyzes the metabolism of adenosine to 5'-adenosine monophosphate. The enzyme exists in two isoforms: a long isoform (ADK-long, ADK-L) and a short isoform (ADK-short, ADK-S). The two isoforms are developmentally regulated and are differentially expressed in distinct subcellular compartments with ADK-L localized in the nucleus and ADK-S localized in the cytoplasm. The nuclear localization of ADK-L and its biochemical link to the transmethylation pathway suggest a specific role for gene regulation via epigenetic mechanisms. Recent evidence reveals an adenosine receptor-independent role of ADK in determining the global methylation status of DNA and thereby contributing to epigenomic regulation. Here we summarize recent progress in understanding the biochemical interactions between adenosine metabolism by ADK-L and epigenetic modifications linked to transmethylation reactions. This review will provide a comprehensive overview of ADK-associated changes in DNA methylation in developmental, as well as in pathological conditions including brain injury, epilepsy, vascular diseases, cancer, and diabetes. Challenges in investigating the epigenetic role of ADK for therapeutic gains are briefly discussed.

Computational exploration of vicine - an alkaloid glycoside mediated pathological hallmark of adenosine kinase to promote neurological disorder

Epilepsy disease is characterized by the neuronal dysfunction or abnormal neuronal activity of the brain which is regulated by astrocytes. These are glial cells and found to be the major regulators of the brain which are guided by the occurrence of adenosine kinase (ADK) enzyme in the central nervous system (CNS). During the normal physiological environment, ADK maintains the level of adenosine in the CNS. Dysfunction of ADK levels results in accumulation of adenosine levels in the CNS that leads to the pathophysiology of the brain such as astrogliosis which is a pathological hallmark of epileptic seizures. Vicine, an alkaloid glycoside in bitter gourd juice (Momordica charantia) is found to be toxic to the human system if the bitter gourd juice is consumed more. This compound inhibits ADK enzyme activity to lead epilepsy and seizure. Here, the toxic effect of vicine targeting ADK using computational predictions was investigated. The 3-dimensional structure of ADK has been constructed using I-Tasser, which has been refined by ModRefiner, GalaxyRefine, and 3D refine and it was endorsed using PROCHECK, ERRAT, and VADAR. 3D structure of the ligand molecule has been obtained from PubChem. Molecular docking has been achieved using AutoDock 4.2 software, from which the outcome showed the effective interaction between vicine and ADK, which attains binding free energy (∆G) of - 4.13 kcal/mol. Vicine molecule interacts with the active region ARG 149 of ADK and inhibits the functions of ADK that may cause imbalance in energy homeostasis. Also, pre-ADMET results robustly propose in which vicine possesses toxicity, and meanwhile, from the Ames test, it was shown as mutagenic. Hence, the results from our study suggest that vicine was shown to be toxic that suppresses the ADK activity to undergo pathological conditions in the neuronal junctions to lead epilepsy.

Inhibition of adenosine kinase attenuates myocardial ischaemia/reperfusion injury

Increased adenosine helps limit infarct size in ischaemia/reperfusion‐injured hearts. In cardiomyocytes, 90% of adenosine is catalysed by adenosine kinase (ADK) and ADK inhibition leads to higher concentrations of both intracellular adenosine and extracellular adenosine. However, the role of ADK inhibition in myocardial ischaemia/reperfusion (I/R) injury remains less obvious. We explored the role of ADK inhibition in myocardial I/R injury using mouse left anterior ligation model. To inhibit ADK, the inhibitor ABT‐702 was intraperitoneally injected or AAV9 (adeno‐associated virus)—ADK—shRNA was introduced via tail vein injection. H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to elucidate the underlying mechanisms. ADK was transiently increased after myocardial I/R injury. Pharmacological or genetic ADK inhibition reduced infarct size, improved cardiac function and prevented cell apoptosis and necroptosis in I/R‐injured mouse hearts. In vitro, ADK inhibition also prevented cell apoptosis and cell necroptosis in H/R‐treated H9c2 cells. Cleaved caspase‐9, cleaved caspase‐8, cleaved caspase‐3, MLKL and the phosphorylation of MLKL and CaMKII were decreased by ADK inhibition in reperfusion‐injured cardiomyocytes. X‐linked inhibitor of apoptosis protein (XIAP), which is phosphorylated and stabilized via the adenosine receptors A2B and A1/Akt pathways, should play a central role in the effects of ADK inhibition on cell apoptosis and necroptosis. These data suggest that ADK plays an important role in myocardial I/R injury by regulating cell apoptosis and necroptosis.

Adenosine kinase is critical for neointima formation after vascular injury by inducing aberrant DNA hypermethylation

AIMS

Adenosine receptors and extracellular adenosine have been demonstrated to modulate vascular smooth muscle cell (VSMC) proliferation and neointima formation. Adenosine kinase (ADK) is a major enzyme regulating intracellular adenosine levels but is function in VSMC remains unclear. Here, we investigated the role of ADK in vascular injury-induced smooth muscle proliferation and delineated the mechanisms underlying its action.

METHODS AND RESULTS

We found that ADK expression was higher in the neointima of injured vessels and in platelet-derived growth factor-treated VSMCs. Genetic and pharmacological inhibition of ADK was enough to attenuate arterial injury-induced neointima formation due to inhibition of VSMC proliferation. Mechanistically, using infinium methylation assays and bisulfite sequencing, we showed that ADK metabolized the intracellular adenosine and potentiated the transmethylation pathway, then induced the aberrant DNA hypermethylation. Pharmacological inhibition of aberrant DNA hypermethylation increased KLF4 expression and suppressed VSMC proliferation as well as the neointima formation. Importantly, in human femoral arteries, we observed increased ADK expression and DNA hypermethylation as well as decreased KLF4 expression in neointimal VSMCs of stenotic vessels suggesting that our findings in mice are relevant for human disease and may hold translational significance.

CONCLUSION

Our study unravels a novel mechanism by which ADK promotes VSMC proliferation via inducing aberrant DNA hypermethylation, thereby down-regulating KLF4 expression and promoting neointima formation. These findings advance the possibility of targeting ADK as an epigenetic modulator to combat vascular injury.

Methotrexate attenuates vascular inflammation through an adenosine-microRNA-dependent pathway

Endothelial cell (EC) activation is an early hallmark in the pathogenesis of chronic vascular diseases. MicroRNA-181b (Mir181b) is an important anti-inflammatory mediator in the vascular endothelium affecting endotoxemia, atherosclerosis, and insulin resistance. Herein, we identify that the drug methotrexate (MTX) and its downstream metabolite adenosine exert anti-inflammatory effects in the vascular endothelium by targeting and activating Mir181b expression. Both systemic and endothelial-specific Mir181a2b2-deficient mice develop vascular inflammation, white adipose tissue (WAT) inflammation, and insulin resistance in a diet-induced obesity model. Moreover, MTX attenuated diet-induced WAT inflammation, insulin resistance, and EC activation in a Mir181a2b2-dependent manner. Mechanistically, MTX attenuated cytokine-induced EC activation through a unique adenosine-adenosine receptor A3-SMAD3/4-Mir181b signaling cascade. These findings establish an essential role of endothelial Mir181b in controlling vascular inflammation and that restoring Mir181b in ECs by high-dose MTX or adenosine signaling may provide a potential therapeutic opportunity for anti-inflammatory therapy.

GATA factor-regulated solute carrier ensemble reveals a nucleoside transporter-dependent differentiation mechanism

Developmental-regulatory networks often include large gene families encoding mechanistically-related proteins like G-protein-coupled receptors, zinc finger transcription factors and solute carrier (SLC) transporters. In principle, a common mechanism may confer expression of multiple members integral to a developmental process, or diverse mechanisms may be deployed. Using genetic complementation and enhancer-mutant systems, we analyzed the 456 member SLC family that establishes the small molecule constitution of cells. This analysis identified SLC gene cohorts regulated by GATA1 and/or GATA2 during erythroid differentiation. As >50 SLC genes shared GATA factor regulation, a common mechanism established multiple members of this family. These genes included Slc29a1 encoding an equilibrative nucleoside transporter (Slc29a1/ENT1) that utilizes adenosine as a preferred substrate. Slc29a1 promoted erythroblast survival and differentiation ex vivo. Targeted ablation of murine Slc29a1 in erythroblasts attenuated erythropoiesis and erythrocyte regeneration in response to acute anemia. Our results reveal a GATA factor-regulated SLC ensemble, with a nucleoside transporter component that promotes erythropoiesis and prevents anemia, and establish a mechanistic link between GATA factor and adenosine mechanisms. We propose that integration of the GATA factor-adenosine circuit with other components of the GATA factor-regulated SLC ensemble establishes the small molecule repertoire required for progenitor cells to efficiently generate erythrocytes.

GATA transcription factors endow blood stem and progenitor cells with activities to produce progeny that transport oxygen to protect cells and tissues, evade pathogens and control physiological processes. GATA factors regulate hundreds of genes, and the actions of these genes mediate important biological functions. While the genes have been documented, many questions remain regarding how the “network” components mediate biological functions. The networks include members of large gene families, and the relationships between the regulation and function of individual family members is not well understood. Analyzing datasets from genetic complementation and enhancer mutant systems revealed that GATA factors regulate an ensemble of membrane transporters termed solute carrier proteins (SLCs), which dictate the small molecule composition of cells. Genetic analyses with Slc29a1, which transports adenosine, revealed its function to promote erythrocyte development, and Slc29a1 attenuated anemia in a mouse model. This study revealed the importance of SLC transporters in GATA factor networks. We propose that the GATA factor-adenosine circuit integrates with other SLCs to establish/maintain the small molecule constitution of progenitor cells as a new mechanism to control blood cell development.

Adenosine metabolism in the vascular system

The concept of extracellular purinergic signaling was first proposed by Geoffrey Burnstock in the early 1970s. Since then, extracellular ATP and its metabolites ADP and adenosine have attracted an enormous amount of attention in terms of their involvement in a wide range of immunomodulatory, thromboregulatory, angiogenic, vasoactive and other pathophysiological activities in different organs and tissues, including the vascular system. In addition to significant progress in understanding the properties of nucleotide- and adenosine-selective receptors, recent studies have begun to uncover the complexity of regulatory mechanisms governing the duration and magnitude of the purinergic signaling cascade. This knowledge has led to the development of new paradigms in understanding the entire purinome by taking into account the multitude of signaling and metabolic pathways involved in biological effects of ATP and adenosine and compartmentalization of the adenosine system. Along with the "canonical route" of ATP breakdown to adenosine via sequential ecto-nucleoside triphosphate diphosphohydrolase-1 (NTPDase1/CD39) and ecto-5'-nucleotidase/CD73 activities, it has now become clear that purine metabolism is the result of concerted effort between ATP release, its metabolism through redundant nucleotide-inactivating and counteracting ATP-regenerating ectoenzymatic pathways, as well as cellular nucleoside uptake and phosphorylation of adenosine to ATP through complex phosphotransfer reactions. In this review I provide an overview of key enzymes involved in adenosine metabolic network, with special emphasis on the emerging roles of purine-converting ectoenzymes as novel targets for cancer and vascular therapies.

Adenosine kinase: A key regulator of purinergic physiology

Adenosine (ADO) is an essential biomolecule for life that provides critical regulation of energy utilization and homeostasis. Adenosine kinase (ADK) is an evolutionary ancient ribokinase derived from bacterial sugar kinases that is widely expressed in all forms of life, tissues and organ systems that tightly regulates intracellular and extracellular ADO concentrations. The facile ability of ADK to alter ADO availability provides a "site and event" specificity to the endogenous protective effects of ADO in situations of cellular stress. In addition to modulating the ability of ADO to activate its cognate receptors (P1 receptors), nuclear ADK isoform activity has been linked to epigenetic mechanisms based on transmethylation pathways. Previous drug discovery research has targeted ADK inhibition as a therapeutic approach to manage epilepsy, pain, and inflammation. These efforts generated multiple classes of highly potent and selective inhibitors. However, clinical development of early ADK inhibitors was stopped due to apparent mechanistic toxicity and the lack of suitable translational markers. New insights regarding the potential role of the nuclear ADK isoform (ADK-Long) in the epigenetic modulation of maladaptive DNA methylation offers the possibility of identifying novel ADK-isoform selective inhibitors and new interventional strategies that are independent of ADO receptor activation.

Tanshinone II A attenuates vascular remodeling through klf4 mediated smooth muscle cell phenotypic switching

The aim of this study is to investigate the therapeutic role of Tanshinone II A, a key integrant from salvia miltiorrhiza, against pathological vascular remodeling. Completed ligation of mouse left common carotid arteries animal model and rat smooth muscle cells used to investigate the role of Tanshinone II A in regulating pathological vascular remodeling through hematoxylin and eosin staining, immunohistochemistry staining, immunofluorescence staining, adenovirus infection, real time PCR and western blotting. Our data demonstrated that Tanshinone II A treatment suppresses vascular injury-induced neointima formation. In vitro studies on rat smooth muscle cell indicated that Tanshinone II A treatment attenuates PDGF-BB induced cell growth, and promotes smooth muscle cell differentiated marker genes expression that induced by rapamycin treatment. Tanshinone II A treatment significant inhibits rat smooth muscle cell proliferation and migration. Tanshinone II A promotes KLF4 expression during smooth muscle phenotypic switching. Overexpression of KLF4 exacerbates Tanshinone II A mediated smooth muscle cell growth inhibition. Tanshinone II A plays a pivotal role in regulating pathological vascular remodeling through KLF4 mediated smooth muscle cell phenotypic switching. This study demonstrated that Tanshinone II A is a potential therapeutic agent for vascular diseases.