Endothelial PPAR-γ protects against vascular thrombosis by downregulating P-selectin expression

Exploring the Role of IRF6 in Perinatal Arterial Ischemic Stroke: A Case of a Newborn with Craniofacial Malformations

Background/Objectives: Ischemic arterial stroke (AIS) is a cerebrovascular event that can occur acutely within the first hours or days of life, presenting as a neurological emergency. To date, clearly defined genetic risk factors for AIS have not been established, although certain genes involved in cerebrovascular regulation mechanisms are suspected to play a role. The Interferon Regulatory Factor 6 (IRF6) gene is a transcription factor involved in craniofacial and epidermal development. Recently, pathogenic variants of IRF6 have been implicated in the cytoprotective pathway of ischemic cerebrovascular disease. The aim of this manuscript is to further support the already-reported association between IRF6 and AIS. Materials and Methods: Genetic counseling and exome sequencing analysis were conducted for diagnostic purposes. Results: We report the case of a female newborn with palatoschisis, cleft palate, sensorineural deafness, facial dysmorphisms, and cutaneous defects who suffered an ischemic stroke in the territory of the left middle cerebral artery on day 1 of life. Family and pregnancy histories revealed no identifiable risk factors, and coagulation studies were normal. Exome sequencing identified a de novo c.1124T>C (p.Phe375Ser) variant in the IRF6 gene. The child developed right spastic hemiplegia and began motor rehabilitation therapy. Recently, a genome-wide association study (GWAS) using m6A-SNPs identified a statistical association between AIS and a single nucleotide polymorphism (SNP) that influences the expression of the IRF6 gene as an expression quantitative trait locus (eQTL). Conclusions: To our knowledge, this is the first report of neonatal ischemic stroke in a child carrying a de novo IRF6 pathogenic variant, further supporting its potential role as a genetic factor influencing cerebrovascular events. Further studies are needed to elucidate the precise relationship between IRF6 and AIS.

Coagulopathy and acute pancreatitis: pathophysiology and clinical treatment

Coagulopathy is a critical pathophysiological mechanism of acute pancreatitis (AP), arising from the complex interplay between innate immune, endothelial cells and platelets. Although initially beneficial for the host, uncontrolled and systemic activation of coagulation cascade in AP can lead to thrombotic and hemorrhagic complications, ranging from subclinical abnormalities in coagulation tests to severe clinical manifestations, such as disseminated intravascular coagulation. Initiation of coagulation activation and consequent thrombin generation is caused by expression of tissue factor on activated monocytes and is ineffectually offset by tissue factor pathway inhibitor. At the same time, endothelial-associated anticoagulant pathways, in particular the protein C system, is impaired by pro-inflammatory cytokines. Also, fibrin removal is severely obstructed by inactivation of the endogenous fibrinolytic system, mainly as a result of upregulation of its principal inhibitor, plasminogen activator inhibitor type 1. Finally, increased fibrin generation and impaired break down lead to deposition of (micro) vascular clots, which may contribute to tissue ischemia and ensuing organ dysfunction. Despite the high burden of coagulopathy that have a negative impact on AP patients' prognosis, there is no effective treatment yet. Although a variety of anticoagulants drugs have been evaluated in clinical trials, their beneficial effects are inconsistent, and they are also characterized by hemorrhagic complications. Future studies are called to unravel the pathophysiologic mechanisms involved in coagulopathy in AP, and to test novel therapeutics block coagulopathy in AP.

Peroxisome proliferator‑activated receptor γ alleviates human umbilical vein endothelial cell injury in deep vein thrombosis by blocking endoplasmic reticulum stress

The present study aimed to explore the role of peroxisome proliferator-activated receptor γ (PPARγ) in the development of deep vein thrombosis (DVT), as well as to discover the potential regulatory mechanism of PPARγ. Human umbilical vein endothelial cells (HUVECs) were treated with modified glycated human serum albumin (M-HSA) to mimic DVT. PPARγ expression and activity were detected using western blot analysis and the corresponding activity detection kit, respectively. Cell Counting Kit-8 and the terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assays were employed to detect cell viability and apoptosis, respectively. The levels of thrombosis-related factors and inflammatory cytokines were detected by ELISA. The levels of oxidative stress-related factors were determined by the corresponding commercial kits. In addition, tunicamycin (TM), the agonist of endoplasmic reticulum stress (ERS), was applied to investigate the potential mechanism. The results indicated that M-HSA caused reduced expression and activity of PPARγ in HUVECs; these effects were reversed by PPARγ overexpression, which significantly inhibited M-HSA-induced cell viability loss, cell apoptosis, inflammation and oxidative stress in HUVECs. In addition, ERS was activated following M-HSA stimulation in HUVECs, but was suppressed by PPARγ overexpression. Furthermore, TM partly abolished the protective role of PPARγ overexpression against cell viability loss, cell apoptosis, inflammation and oxidative stress in M-HSA-induced HUVECs. In summary, PPARγ antagonized M-HSA-induced HUVEC injury by suppressing the activation of ERS, which provides a novel strategy for the treatment of DVT.

Notoginsenoside Fc alleviates oxidized low-density lipoprotein-induced endothelial cell dysfunction and upregulates PPAR-γ in vitro

BACKGROUND

Deep venous thrombosis (DVT) is a prevalent vascular disease and a major cause of morbidity and mortality worldwide. Notoginsenoside Fc (NFc) is a protopanaxadiol-type saponin that has been shown to have beneficial effects on several disorders. However, its function in DVT is unclear.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to mimic DVT in vitro and treated with NFc to investigate its functions. CCK-8 assay was utilized for measuring cell viability. Western blotting was used for detecting protein levels of proinflammatory cytokines, apoptosis-related markers, and peroxisome proliferator-activated receptor-γ (PPAR-γ). Flow cytometry was performed for cell apoptosis detection. Levels of oxidative stress-related markers were examined by the DCFH-DA method and ELISA. RT-qPCR was utilized for the measurement of PPAR-γ mRNA level.

RESULTS

NFc increased the viability and suppressed inflammation, apoptosis, and oxidative stress in ox-LDL-treated HUVECs. NFc treatment induced upregulation of PPAR-γ in HUVECs.

CONCLUSION

NFc mitigates ox-LDL-induced dysfunction of HUVECs.

High-Dose Vitamin C Alleviates Pancreatic Necrosis by Inhibiting Platelet Activation Through the CXCL12/CXCR4 Pathway in Severe Acute Pancreatitis

BACKGROUND

Platelet activation in the early stage of pancreatitis is the key step developing into pancreatic necrosis. Studies suggested that vitamin C (Vit C) can inhibit platelet activity by targeting CXCL12/CXCR4 pathway. High-dose Vit C were showed to reduce pancreatic necrosis in severe acute pancreatitis (SAP) but the mechanism remains unclear. Here we speculate high-dose Vit C reduce pancreatic necrosis by inhibiting platelet activation through downregulating CXCL12/CXCR4 pathway.

METHODS

The pancreatic microcirculation of rats was observed by intravital microscopy. The platelet activity of SAP rats treated with or without high-dose Vit C was analyzed by platelet function test. Besides, the activity of platelets preincubated with high-dose Vit C or vehicle from SAP patients was also evaluated. Then, the TFA (CXCR4 agonist) and rCXCL12 were used to neutralize the effect of high-dose Vit C in SAP rats treated with high-dose Vit C. Meanwhile, the levels of enzymes and inflammatory cytokines in rat plasma, and rats' pancreatic histopathology and mortality were assessed.

RESULTS

Platelets from animals and patients with SAP are more sensitive to agonists and are more easily activated. Administration of high-dose Vit C significantly ameliorated excessive activation of platelets in SAP rats, ultimately increasing the microvessel density and inducing microthrombus and blood stasis; these results were consistent with clinical sample analysis. Moreover, high-dose Vit C significantly inhibited the release of amylase, lipase, TNF-α, and IL-6 in SAP rat plasma, reducing pancreatic damage and the mortality of SAP rats. However, using TFA and rCXCL12 significantly reversed the effect of high-dose Vit C on excessive activation of platelets, aggravating microcirculation impairment and pancreatic damage.

CONCLUSION

The present study suggests that high-dose Vit C can ameliorate pancreatic necrosis by improving microcirculation disorders of SAP. For the first time, the underlying mechanism is related with inhibiting platelet activation through the CXCL12/CXCR4 pathway.

Selective PPARγ modulator diosmin improves insulin sensitivity and promotes browning of white fat

Peroxisome proliferator-activated receptor γ (PPARγ) is a master regulator of adipocyte differentiation, glucolipid metabolism, and inflammation. Thiazolidinediones are PPARγ full agonists with potent insulin-sensitizing effects, whereas their oral usage is restricted because of unwanted side effects, including obesity and cardiovascular risks. Here, via virtual screening, microscale thermophoresis analysis, and molecular confirmation, we demonstrate that diosmin, a natural compound of wide and long-term clinical use, is a selective PPARγ modulator that binds to PPARγ and blocks PPARγ phosphorylation with weak transcriptional activity. Local diosmin administration in subcutaneous fat (inguinal white adipose tissue [iWAT]) improved insulin sensitivity and attenuated obesity via enhancing browning of white fat and energy expenditure. Besides, diosmin ameliorated inflammation in WAT and liver and reduced hepatic steatosis. Of note, we determined that iWAT local administration of diosmin did not exhibit obvious side effects. Taken together, the present study demonstrated that iWAT local delivery of diosmin protected mice from diet-induced insulin resistance, obesity, and fatty liver by blocking PPARγ phosphorylation, without apparent side effects, making it a potential therapeutic agent for the treatment of metabolic diseases.

Pathogenesis and Therapy of Coagulation Disorders in Severe Acute Pancreatitis

Ischemia superimposed upon pancreatic edema leads to acute necrotizing pancreatitis. One possible mechanism contributing to ischemia is intravascular thrombogenesis since fibrin deposits have been detected in pancreatic capillaries by electron microscope. Current experimental and clinical data provided compelling evidence that the disorders in the blood coagulation system play a critical role in the pathogenesis of severe acute pancreatitis (SAP). This leads to microcirculatory failure of intra- and extrapancreatic organs and multiple organ failure and increases the case fatality rate. However, the mechanism of coagulopathy underlying SAP is not yet clear, although some anticoagulant drugs have entered clinical practice showing improvement in prognosis. Thus, enhanced understanding of the process might improve the treatment strategies with safety and high efficacy. Herein, the pathogenesis of the coagulation system of SAP was reviewed with a focus on the coagulation pathway, intercellular interactions, and complement system, thereby illustrating some anticoagulant therapies and potential therapeutic targets.

Role of Neutrophils and NETs in Animal Models of Thrombosis

Thrombosis is one of the major causes of mortality worldwide. Notably, it is not only implicated in cardiovascular diseases, such as myocardial infarction (MI), stroke, and pulmonary embolism (PE), but also in cancers. Understanding the cellular and molecular mechanisms involved in platelet thrombus formation is a major challenge for scientists today. For this purpose, new imaging technologies (such as confocal intravital microscopy, electron microscopy, holotomography, etc.) coupled with animal models of thrombosis (mouse, rat, rabbit, etc.) allow a better overview of this complex physiopathological process. Each of the cellular components is known to participate, including the subendothelial matrix, the endothelium, platelets, circulating cells, and, notably, neutrophils. Initially known as immune cells, neutrophils have been considered to be part of the landscape of thrombosis for more than a decade. They participate in this biological process through their expression of tissue factor (TF) and protein disulfide isomerase (PDI). Moreover, highly activated neutrophils are described as being able to release their DNA and thus form chromatin networks known as “neutrophil extracellular traps” (NETs). Initially, described as “dead sacrifices for a good cause” that prevent the dissemination of bacteria in the body, NETs have also been studied in several human pathologies, such as cardiovascular and respiratory diseases. Many articles suggest that they are involved in platelet thrombus formation and the activation of the coagulation cascade. This review presents the models of thrombosis in which neutrophils and NETs are involved and describes their mechanisms of action. We have even highlighted the medical diagnostic advances related to this research.

Relationship between PPAR-γ gene polymorphisms and ischemic stroke risk: A meta-analysis

BACKGROUND

Published researches have suggested some associations between PPAR-γ and ischemic stroke (IS) development. This meta-analysis was conducted to evaluate the association between PPAR-γ gene polymorphisms and IS risk.

MATERIALS AND METHODS

A systematic search was conducted in PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and WanFang databases. The pooled association of odd ratios (ORs) and its 95% confidence interval (CI) was calculated to assess the IS risk of PPAR-γ rs1801282 C/G and rs3856806 C/T polymorphisms. Furthermore, the heterogeneity test, cumulative analyses, sensitivity analyses, and publication bias were conducted.

RESULT

Sixteen publications with 3786 cases and 5343 controls were identified. Overall findings indicated that rs1801282 C/G polymorphism may be associated with an increased risk for IS (GG vs. CC: OR = 2.17 95%CI = 1.09-4.35, p = .03, I²  = 0%; GG vs. CC+CG: OR = 2.15, 95%CI = 1.07-4.32, p = .03, I²  = 0%). The similar results were also found in the subgroup analysis. In addition, no significant association was observed between rs3856806 C/T polymorphism and IS risk.

CONCLUSION

In conclusion, our study showed that PPAR-γ rs1801282 C/G polymorphism probably plays an important role in IS occurrence. The result should be verified with more studies in the future.

Formononetin protects against ox-LDL-induced endothelial dysfunction by activating PPAR-γ signaling based on network pharmacology and experimental validation

Formononetin (FMNT), a flavonoid identified from the Chinese herb Astragalus membranaceus, possesses anti-inflammatory or anti-oxidative properties in different human diseases. This study aims to comprehensively elucidate the function of FMNT in atherosclerosis and its underlying mechanisms. Online public databases were used to identify the drug-disease targets. Protein–protein interaction (PPI), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were applied to explore the potential targets and signaling pathways involved in FMNT against atherosclerosis. Human umbilical vein endothelial cells (HUVECs) were exposed to oxidized low-density lipoprotein (ox-LDL) to construct an atherosclerosis cell model in vitro. Endothelial cell function was assessed via examining cell proliferation, inflammatory factors, oxidative markers, reactive oxygen species (ROS), and apoptosis. Western blot was performed to detect the expression of cyclooxygenase-2 (COX-2), endothelial nitric oxide synthase (eNOS), cleaved caspase-3, and peroxisome proliferator-activated receptor-γ (PPAR-γ). A total of 39 overlapping target genes of FMNT and atherosclerosis were identified. Through the PPI network analysis, 14 hub genes were screened and found to be closely relevant to inflammation, oxidative stress, and apoptosis. Results of KEGG pathway assays indicated that lots of targets were enriched in PPAR signaling. Functionally, FMNT could protect against ox-LDL-induced inflammatory reaction, oxidative stress, and apoptosis in HUVECs. Moreover, FMNT attenuated ox-LDL-mediated inactivation of PPAR-γ signaling. GW9662, a PPAR-γ antagonist, reversed the inhibitory effect of FMNT on ox-LDL-induced endothelial injury. In conclusion, FMNT alleviates ox-LDL-induced endothelial injury in HUVECs by stimulating PPAR-γ signaling, providing a theoretical basis for employing FMNT as a potential drug to combat atherosclerosis.

Abbreviations: FMNT: formononetin; PPI: protein–protein interaction; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; HUVECs: human umbilical vein endothelial cells; ox-LDL: oxidized low-density lipoprotein; COX-2: cyclooxygenase-2; eNOS: endothelial nitric oxide synthase; PPAR-γ: peroxisome proliferator-activated receptor-γ; CVD: cardiovascular disease; TCM: traditional Chinese medicines; OGDR: oxygen-glucose deprivation/reoxygenation; ROS: reactive oxygen species; FBS: fetal bovine serum; CCK-8: cell counting kit-8; EdU: 5-Ethynyl-2ʹ-deoxyuridine; SOD: antioxidant enzymes superoxide dismutase; MDA: malondialdehyde; DCFH-DA: 2ʹ,7ʹ-dichlorofluorescein-diacetate; PVDF: polyvinylidene fluoride; ANOVA: one-way analysis of variance; PPARs: peroxisome proliferation-activated receptors

Histone H4 aggravates inflammatory injury through TLR4 in chlorine gas-induced acute respiratory distress syndrome

Background

Chlorine gas (Cl₂) exposure remains a public health concern in household, occupational, and transportation accidents around the world. The death rate associated with acute respiratory distress syndrome (ARDS) caused by high concentrations of Cl₂ is very high, mainly because the pathogenesis of ARDS remains unclear. Histone H4 has been identified as an important endogenous pro-inflammatory molecule. The present study aimed to examine the pathogenic role of histone H4 in Cl₂-induced ARDS.

Methods

ARDS was induced by Cl₂ exposure in male C57BL/6 mice. Circulating histone H4, blood gas, pulmonary edema, endothelial activation, and neutrophil infiltration were measured during acute lung injury (ALI). Histone H4 or anti-H4 antibody was administered through the tail vein 1 h prior to Cl₂ exposure to study the pathogenic role of histone H4. Toll-like receptor 2 knock-out (Tlr2-KO) and Tlr4-KO mice were used in conjunction with blocking antibody against TLR1, TLR2, TLR4, or TLR6 to explore the mechanism involved in histone H4-mediated injury.

Results

Cl₂ exposure induced a concentration-dependent ALI. The levels of circulating histone H4 were positively correlated with Cl₂ concentrations. Pretreatment with intravenous histone H4 further aggravated lethality rate, blood gas, endothelial activation, and neutrophil infiltration, while anti-H4 antibody showed protective effects. Tlr4 deficiency improved lethality rate, blood gas, and pulmonary edema, and prevented endothelial and neutrophil activation caused by Cl₂ exposure. More importantly, Tlr4 gene deletion greatly diminished the effect of histone H4 or anti-H4 antibody observed in wild-type (WT) mice. The impact of Tlr2 on inflammatory injury was not significant. The role of TLRs was also validated by endothelial activation mediated by histone H4 in vitro.

Conclusions

Circulating histone H4 played a pro-inflammatory role in ARDS caused by Cl₂. TLR4 was closely involved in histone H4-mediated inflammatory injury. Therefore, intervention targeting histone H4 is potentially protective.

Nephrotic syndrome-associated hypercoagulopathy is alleviated by both pioglitazone and glucocorticoid which target two different nuclear receptors

BACKGROUND

Thrombosis is a potentially life-threatening nephrotic syndrome (NS) complication. We have previously demonstrated that hypercoagulopathy is proportional to NS severity in rat models and that pioglitazone (Pio) reduces proteinuria both independently and in combination with methylprednisolone (MP), a glucocorticoid (GC). However, the effect of these treatments on NS-associated hypercoagulopathy remains unknown. We thus sought to determine the ability of Pio and GC to alleviate NS-associated hypercoagulopathy.

METHODS

Puromycin aminonucleoside-induced rat NS was treated with sham, Low- or High-dose MP, Pio, or combination (Pio + Low-MP) and plasma was collected at day 11. Plasma samples were collected from children with steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS) upon presentation and after 7 weeks of GC therapy. Plasma endogenous thrombin potential (ETP), antithrombin (AT) activity, and albumin (Alb) were measured using thrombin generation, amidolytic, and colorimetric assays, respectively.

RESULTS

In a rat model of NS, both High-MP and Pio improved proteinuria and corrected hypoalbuminemia, ETP and AT activity (p < .05). Proteinuria (p = .005) and hypoalbuminemia (p < .001) were correlated with ETP. In childhood NS, while ETP was not different at presentation, GC therapy improved proteinuria, hypoalbuminemia, and ETP in children with SSNS (p < .001) but not SRNS (p = .330).

CONCLUSIONS

Both Pio and GC diminish proteinuria and significantly alleviate hypercoagulopathy. Both Pio and MP improved hypercoagulopathy in rats, and successful GC therapy (SSNS) also improved hypercoagulopathy in childhood NS. These data suggest that even a partial reduction in proteinuria may reduce NS-associated thrombotic risk.

A comparative pharmacogenomic analysis of three classic TCM prescriptions for coronary heart disease based on molecular network modeling

Traditional Chinese medicine (TCM) has evolved over several thousands of years, which has been shown to be efficacious in the treatment of ischemic heart disease. Three classical TCM prescriptions, namely Xuefu Zhuyu Decoction, Zhishi Xiebai Guizhi Decoction, and Gualou Xiebai Banxia Decoction, have been extensively used in the treatment of coronary heart disease (CHD). Based on molecular network modeling, we performed a comparative pharmacogenomic analysis to systematically determine the drug-targeting spectrum of the three prescriptions at molecular level. Wide-area target molecules of CHD were covered, which was a common feature of the three decoctions, demonstrating their therapeutic functions. Meanwhile, collective signaling involved metabolic/pro-metabolic pathways, driving and transferring pathways, neuropsychiatric pathways, and exocrine or endocrine pathways. These organized pharmacological disturbance was mainly focused on almost all stages of CHD intervention, such as anti-atherosclerosis, lipid metabolism, inflammation, vascular wall function, foam cells formation, platelets aggregation, thrombosis, arrhythmia, and ischemia-reperfusion injury. In addition, heterogeneity analysis of the global pharmacological molecular spectrum revealed that signaling crosstalk, cascade convergence, and key targets were tendentious among the three decoctions. After all, it is unadvisable to rank the findings on targeting advantages of the three decoctions. Comparative pharmacological evidence may provide an appropriate decoction scheme for individualized intervention of CHD.

Correlation between P-selectin rs1800807 and rs1800808 Gene polymorphisms and plasma soluble P-selectin concentrations in patients with atrial fibrillation complicated with thromboembolism in Xinjiang, China

This study is to investigate the relationship of P-selectin (Ps) gene rs1800807 and rs1800808 polymorphisms with plasma soluble P-selectin (sPs) in Han, Uygur, and Kazakh people with atrial fibrillation (AF) and thromboembolism (TE) in Xinjiang, China.A total of 778 Han patients (including 131 patients with AF and TE, 229 patients with AF and 418 healthy individuals), 660 Uygur patients (including 118 patients with AF and TE, 232 patients with AF and 310 healthy individuals), and 505 Kazakh patients (including 42 patients with AF and TE, 156 patients with AF and 307 healthy individuals) were enrolled in this study. Polymerase chain reaction-restriction fragment length polymorphism and direct DNA sequence analysis were used to analyze the polymorphisms of rs1800807 and rs1800808 of Ps gene. ELISA was used to determine the plasma sPs level. The association between plasma sPs levels and Ps gene polymorphisms was further analyzed.The sPs concentrations of GG genotype at rs1800807 locus in the Han, Uygur and Kazakh ethnic groups in Xinjiang, China were significantly higher than those of the CC genotype and CG genotype (P < .05). In the rs1800808 locus, plasma sPs concentrations of the heterozygous mutant CT genotypes in Han and Uygur populations were significantly higher than those in the CC and TT genotypes, whereas the plasma sPs concentrations in Kazakh TT genotypes were significantly higher than those in the CC and CT genotypes (P < .05). Among different ethnic groups, there were significant differences in sPs levels of rs1800807 and rs1800808 genotypes (P < .05).Plasma sPs concentrations are associated with Ps genotypes and sPs concentration of the same genotype shows racial differences.

Endothelial PPARγ Is Crucial for Averting Age-Related Vascular Dysfunction by Stalling Oxidative Stress and ROCK

Aging plays a significant role in the progression of vascular diseases and vascular dysfunction. Activation of the ADP-ribosylation factor 6 and small GTPases by inflammatory signals may cause vascular permeability and endothelial leakage. Pro-inflammatory molecules have a significant effect on smooth muscle cells (SMC). The migration and proliferation of SMC can be promoted by tumor necrosis factor alpha (TNF-α). TNF-α can also increase oxidative stress in SMCs, which has been identified to persuade DNA damage resulting in apoptosis and cellular senescence. Peroxisome proliferator-activated receptor (PPAR) acts as a ligand-dependent transcription factor and a member of the nuclear receptor superfamily. They play key roles in a wide range of biological processes, including cell differentiation and proliferation, bone formation, cell metabolism, tissue remodeling, insulin sensitivity, and eicosanoid signaling. The PPARγ activation regulates inflammatory responses, which can exert protective effects in the vasculature. In addition, loss of function of PPARγ enhances cardiovascular events and atherosclerosis in the vascular endothelium. This appraisal, therefore, discusses the critical linkage of PPARγ in the inflammatory process and highlights a crucial defensive role for endothelial PPARγ in vascular dysfunction and disease, as well as therapy for vascular aging.

Omega-9 Oleic Acid, the Main Compound of Olive Oil, Mitigates Inflammation during Experimental Sepsis

The Mediterranean diet, rich in olive oil, is beneficial, reducing the risk of cardiovascular diseases and cancer. Olive oil is mostly composed of the monounsaturated fatty acid omega-9. We showed omega-9 protects septic mice modulating lipid metabolism. Sepsis is initiated by the host response to infection with organ damage, increased plasma free fatty acids, high levels of cortisol, massive cytokine production, leukocyte activation, and endothelial dysfunction. We aimed to analyze the effect of omega-9 supplementation on corticosteroid unbalance, inflammation, bacterial elimination, and peroxisome proliferator-activated receptor (PPAR) gamma expression, an omega-9 receptor and inflammatory modulator. We treated mice for 14 days with omega-9 and induced sepsis by cecal ligation and puncture (CLP). We measured systemic corticosterone levels, cytokine production, leukocyte and bacterial counts in the peritoneum, and the expression of PPAR gamma in both liver and adipose tissues during experimental sepsis. We further studied omega-9 effects on leukocyte rolling in mouse cremaster muscle-inflamed postcapillary venules and in the cerebral microcirculation of septic mice. Here, we demonstrate that omega-9 treatment is associated with increased levels of the anti-inflammatory cytokine IL-10 and decreased levels of the proinflammatory cytokines TNF-α and IL-1β in peritoneal lavage fluid of mice with sepsis. Omega-9 treatment also decreased systemic corticosterone levels. Neutrophil migration from circulation to the peritoneal cavity and leukocyte rolling on the endothelium were decreased by omega-9 treatment. Omega-9 also decreased bacterial load in the peritoneal lavage and restored liver and adipose tissue PPAR gamma expression in septic animals. Our data suggest a beneficial anti-inflammatory role of omega-9 in sepsis, mitigating leukocyte rolling and leukocyte influx, balancing cytokine production, and controlling bacterial growth possibly through a PPAR gamma expression-dependent mechanism. The significant reduction of inflammation detected after omega-9 enteral injection can further contribute to the already known beneficial properties facilitated by unsaturated fatty acid-enriched diets.

Rosuvastatin relieves myocardial ischemia/reperfusion injury by upregulating PPAR‑γ and UCP2

The present study aimed to investigate whether pretreatment with rosuvastatin (RS) can provide cardioprotection in a myocardial ischemia/reperfusion (MI/R) model. The protective effect of RS on myocardial oxygen-glucose deprivation/reperfusion (OGD/R) injury was also evaluated by upregulating peroxisome proliferator-activated receptor-γ (PPAR-γ). In the present study, MI/R model was established and activities of superoxide dismutase (SOD), lactate dehydrogenase (LDH), creatine kinase-muscle/brain (CK-MB), malondialdehyde (MDA), and troponin I/T were measured. The infarct size was measured using Evans blue staining and cell viability was measured by MTT assay. Reactive oxygen species (ROS) levels were assessed by flow cytometry. Caspase-9, cytochrome c (cyt c), mitochondrial uncoupling protein 2 (UCP2) and PPAR-γ expression levels were detected by reverse transcription-quantitative polymerase chain reaction and western blotting. The results indicated that RS increased SOD activity, and decreased LDH, CK-MB, MDA and troponin I/T activities. The effect of RS was reversed by atractyloside (ATR). RS inhibited myocardial infarct size, downregulated expression of caspase-9 and cyt c and upregulated expression of UCP2 and PPAR-γ by inhibiting ATR. Furthermore, the results indicated that RS promoted cardiomyocyte viability, inhibited LDH release, reduced ROS production, decreased expression of caspase-9 and cyt c, and increased expression of UCP2 and PPAR-γ following OGD/R damage. Therefore, the present study demonstrated that RS protects primary myocardial cells against OGD/R injury by regulating PPAR-γ and UCP2. RS may be a promising therapeutic agent for treatment of MI/R injury.

Panax notoginseng saponins reduce high-risk factors for thrombosis through peroxisome proliferator-activated receptor -γ pathway

The classic Virchow theory suggests that blood stasis, hypercoagulability and endothelial dysfunction are three major factors that cause venous thrombosis (VT). It is a complicated biological process involved multi-factors. Platelet plays a central role and participates in multiple links of this process. Panax notoginseng saponins (PNS), the principal constituents derived from panax notoginseng, has been widely described for its anti-platelet activity. However, its potential mechanism against platelet aggregation has not been clarified. In this present study, we evaluated the anti-platelet effects of PNS on thrombin-induced platelet activation and its possible molecular mechanism of action, and further explored the therapeutic action of PNS on thrombin induced hypercoagulability in rat. Our results showed that PNS treatment inhibited platelet aggregation induced by thrombin, which was accompanied with over-expression of Peroxisome proliferator-activated receptor γ (PPAR-γ) protein, mRNA and upregulation of phosphatidylinositol 3 kinase (PI₃K)/ protein kinase B (Akt)/ endothelial nitric oxide synthase (eNOS) pathway in platelet, and this effect could be reversed by PPAR-γ inhibitor T0070907. In vivo, PNS significantly reversed thrombin-induced hypercoagulable state in rat which was accompanied by PPAR-γ protein and mRNA upregulation in rat lung. In conclusion, these data suggested that PNS could suppress thrombin-induced platelet aggregation in vitro and effectively improve hypercoagulable state in vivo and PNS-induced activation of PPAR-γ and its downstream PI₃K/Akt/eNOS pathway played the central role.

Docking based design of diastereoisomeric MTCA as GPIIb/IIIa receptor inhibitor

In GPIIb/IIIa mediated arterial thrombosis platelet activation plays a central role. To discover platelet activation inhibitor the pharmacophores of GPIIb/IIIa receptor inhibitors and anti-thrombotic agents were analyzed. This led to the design of (1R,3S)- and (1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acids as GPIIb/IIIa inhibitors. Comparing to (1S,3S)-isomer (1R,3S)-isomer had lower cdocker interaction energy. AFM image showed that the minimal effective concentration of (1S,3S)-isomer and (1R,3S)-isomer inhibiting platelet activation were 10^-5 M and 10^-6 M, respectively. In vivo 1 μmol/kg of oral (1S,3S)-isomer effectively inhibited the rats to form arterial thrombus and down regulated GPIIb/IIIa expression, but the activities were significantly lower than those of 1 μmol/kg of oral (1R,3S)-isomer. Both (1S,3S)-isomer and (1R,3S)-isomer can be safely used for structural modifications, but (1R,3S)-isomer should be superior to (1S,3S)-isomer.

The Transcription Factor IRF6 Co-Represses PPARγ-Mediated Cytoprotection in Ischemic Cerebrovascular Endothelial Cells

Activation of peroxisome proliferator-activated receptor gamma (PPARγ) in the cerebrovascular endothelium is a key suppressor of post-stroke brain damage. However, the role of PPARγ’s co-regulators during cerebral ischemia remains largely unknown. Here, we show that the transcription factor IRF6 is a novel PPARγ co-regulator that directly binds to and suppresses PPARγ activity in murine cerebrovascular endothelial cells. Moreover, IRF6 was also revealed to be a transcriptional target of PPARγ suppression, with PPARγ silencing significantly promoting IRF6 expression in cerebrovascular endothelial cells. In addition, IRF6 silencing significantly promoted pioglitazone’s cytoprotective effects in ischemic murine cerebrovascular endothelial cells. Mechanistically, IRF6 significantly suppressed PPARγ’s transcriptional inhibition of the ischemia-induced, pro-apoptotic microRNA miR-106a. In conclusion, we identified IRF6 as a novel PPARγ co-suppressor that serves a key role in suppressing PPARγ-mediated cerebrovascular endothelial cytoprotection following ischemia. Further investigation into IRF6 and other PPARγ co-regulators should provide additional insights into PPARγ’s cytoprotective role in the cerebrovascular endothelium following stroke.

MicroRNA-27a/b mediates endothelin-1-induced PPARγ reduction and proliferation of pulmonary artery smooth muscle cells

The down-regulation of peroxisome proliferator-activated receptor γ (PPARγ) expression has been found to correlate with the proliferation of pulmonary artery smooth muscle cells (PASMC), pulmonary vascular remodeling and pulmonary hypertension, while the molecular mechanisms underlying PPARγ reduction in PASMC remain largely unclear. The aim of the current study is to address this issue. Endothelin-1 (ET-1) dose- and time-dependently resulted in PPARγ reduction and proliferation of primary cultured rat PASMC, which was accompanied by the activation of nuclear factor-kappaB (NF-κB) and subsequent induction of microRNA-27a/b (miR-27a/b) expression. Chromatin immunoprecipitation assay revealed that NF-κB directly bound to the promoter regions of miR-27a/b. Luciferase reporter assay identified that miR-27a/b directly regulates the expression of PPARγ in PASMC. Further study indicated that the presence of either NF-κB inhibitor pyrrolidinedithiocarbamate or prior silencing miR-27a/b with anti-miRNA oligonucleotides suppressed ET-1-induced PPARγ reduction and proliferation of PASMC, while overexpression of miR-27a/b reduced PPARγ expression and enhanced PASMC proliferation. Taken together, our study demonstrates that ET-1 stimulates miR-27a/b expression by activation of the NF-κB pathway, which in turn results in PPARγ reduction and contributes to ET-1-induced PASMC proliferation.

The Protective Effect of Apigenin on Myocardial Injury in Diabetic Rats mediating Activation of the PPAR-γ Pathway

We substantiated the role of peroxisome proliferator-activated receptor-γ (PPAR-γ) activation in the protective effect of apigenin against the myocardial infarction (MI) in diabetic rats. Diabetes was induced by intraperitoneal administration of a single dose of streptozotocin (55 mg/kg). The study groups included diabetic rats receiving vehicle, apigenin (75 mg/kg/day, orally), GW9662 (1 mg/kg/day, intraperitoneally), and a combination of apigenin and GW9662 for 14 days. The MI was induced in all the study groups except the diabetic control group by subcutaneous injection of 100 mg/kg/day of isoproterenol on the two terminal days. The diabetes and isoproterenol-induced MI was evident as a reduction in the maximal positive and negative rate of developed left ventricular pressure and an increase in the left ventricular end-diastolic pressure. The activities of creatine kinase on myocardial bundle (CK-MB) and lactate dehydrogenase (LDH) were also reduced. Apigenin treatment prevented the hemodynamic perturbations, restored the left ventricular function and reinstated a balanced redox status. It protected rats against an MI by attenuating myonecrosis, edema, cell death, and oxidative stress. GW9662, a PPAR-γ antagonist reversed the myocardial protection conferred by apigenin. Further, an increase in the PPAR-γ expression in the myocardium of the rats receiving apigenin reinforces the role of PPAR-γ pathway activation in the cardioprotective effects of apigenin.

P-selectin can promote thrombus propagation independently of both von Willebrand factor and thrombospondin-1 in mice

Essentials The main receptor for platelet glycoprotein (GP) Ibα is von Willebrand factor (VWF). P-selectin and thrombospondin-1 (TSP1) have been suggested as counter receptors for GPIbα. In a laser injury model, P-selectin promotes thrombus propagation independently of VWF and TSP1. In a laser injury model, thrombus persists in interleukin-4 receptor α/GPIbα-transgenic mice.

SUMMARY

Background P-selectin and thrombospondin-1 (TSP1) have been suggested as counter ligands that may mediate GPIbα-dependent thrombus growth independently of von Willebrand factor (VWF) in vitro. However, residual thrombus formation still persists in Vwf -/- Tsp1-/- mice, suggesting existence of other mechanisms that modulate thrombus propagation. Objective We determined whether P-selectin modulates thrombus propagation in injured arterioles independently of TSP1 and VWF. Methods CD-62P blocking antibody in Vwf -/- Tsp1-/- mice was used to inhibit P-selectin. We determined thrombus growth kinetics in two models of thrombosis: FeCl3 injury-induced and laser injury-induced thrombosis. Results In a 10% FeCl3 injury-induced thrombosis model, the initial platelet adhesion, time to form first thrombus, and non-occlusive residual thrombus growth kinetics were comparable between P-selectin-blocking antibody-treated Vwf -/- Tsp1-/- mice and control IgG-treated Vwf -/- Tsp1-/- mice. On the other hand, in a laser injury-induced thrombosis model, residual thrombus growth kinetics were significantly decreased in P-selectin-blocking antibody-treated Vwf -/- Tsp1-/- mice vs. control IgG-treated Vwf -/- Tsp1-/- mice. Because P-selectin has been suggested as a counter ligand for platelet GPIbα, we determined the role of GPIbα in a laser injury-induced thrombosis model. Surprisingly, in a laser injury model, unlike in a FeCl3 injury model, thrombus formation was not completely inhibited in IL4Rα/GPIbα-tg mice. Residual thrombus growth kinetics were comparable between P-selectin-blocking antibody-treated IL4Rα/GPIbα-tg mice and control IgG-treated IL4Rα/GPIbα-tg mice. Comparison of slopes over time showed that residual thrombus growth kinetics were comparable in P-selectin-blocking antibody-treated Vwf -/- Tsp1-/- and control IgG-treated IL4Rα/GPIbα-tg mice Conclusion In a laser injury-induced thrombosis model, P-selectin modulates thrombus propagation independently of VWF and TSP1.

IQCA-TASS: a nano-scaled P-selectin inhibitor capable of targeting thrombus and releasing IQCA/TARGD(S)S in vivo

Thrombosis is a serious threat to human health worldwide. Tetrahydroisoquinoline-3-carboxylic acid (IQCA) is an antithrombotic agent, while Thr-Ala-Arg-Gly-Asp(Ser)-Ser (TASS) can target thrombus.

Update on cardiovascular disease in lupus

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE) and cannot be fully explained by traditional cardiovascular risk factors. Recent immunologic discoveries have outlined putative pathways in SLE that may also accelerate the development of atherosclerosis.

RECENT FINDINGS

Aberrant innate and adaptive immune responses implicated in lupus pathogenesis may also contribute to the development of accelerated atherosclerosis in these patients. Defective apoptosis, abnormal lipoprotein function, autoantibodies, aberrant neutrophil responses, and a dysregulated type I interferon pathway likely contribute to endothelial dysfunction. SLE macrophages have an inflammatory phenotype that may drive progression of plaque.

SUMMARY

Recent discoveries have placed increased emphasis on the immunology of atherosclerotic cardiovascular disease. Understanding the factors that drive the increased risk for cardiovascular disease in SLE patients may provide selective therapeutic targets for reducing inflammation and improving outcomes in atherosclerosis.

DHDMIQK(KAP): a novel nano-delivery system of dihydroxyl-tetrahydro-isoquinoline-3-carboxylic acid and KPAK towards the thrombus

Vascular thrombosis is a major risk of the onset of stroke and so novel therapeutic candidates have been attracting interest. In this context, here docking based computer assisted screening and mesoscale simulation were used to design N-[(S)-6,7-dihydroxy-1,1-dimethyl-1,2,3,4-tetrahydroisoquinoline-3-carbonyl]-Lys(Pro-Ala-Lys), DHDMIQK(KAP), for inhibiting P-selectin expression. In vitro, 1 nM of DHDMIQK(KAP) effectively down-regulated P-selectin expression. In water, in rat plasma and in the solid state DHDMIQK(KAP) formed nanoparticles of a size capable of suitable delivery in the blood circulation. FT-MS and NOESY 2D NMR spectra showed DHDMIQK(KAP) formed hexamers, identified the intermolecular interactions of the hexamer, and assigned the hexamer a butterfly like conformation. Transmission electron microscopy, scanning electron microscopy and atomic force microscopy (AFM) imaged DHDMIQK(KAP) forming size-suitable nanoparticles for safe delivery in the blood circulation. In particular, AFM images showed that the nanoparticles effectively adhered onto the surfaces of the platelets. In vivo DHDMIQK(KAP) lysed the thrombus and inhibited thrombosis with a minimal effective dose of 0.01 nmol kg^-1. FT-MS spectrum analyses defined a specific distribution of DHDMIQK(KAP) in the thrombus, but not in the blood and vital organs. Therefore, DHDMIQK(KAP) should be a novel nano-delivery system of 6,7-dihydroxyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid and KPAK to target the thrombus.

A novel lead of P-selectin inhibitor: Discovery, synthesis, bioassays and action mechanism

By docking 126 derivatives of β-carboline-3-carboxylic acid, tetrahydro-β-carboline-3-carboxylic acid and indoloquinolizine into the active pocket of P-selectin (2-(3-(hydroxymethyl)-9H-pyrido[3,4-b]indol-1-yl)ethyl)-l-phenylalanine (HMCEF) was assigned a novel inhibitor. ELISA and flow cytometry experiments showed that HMCEF effectively down-regulated P-selectin expression and supported the rationality of the computer assistant screening, while UV spectrum experiments demonstrated that HMCEF directly bound to P-selectin. In vivo HMCEF dose dependently inhibited the rats and mice to form thrombus and had a minimal effective dose of 20nmol/kg, dose dependently inhibited inflammatory response of mice and had a minimal effective dose of 20nmol/kg. The decrease of serum TNFα and IL-8 of the treated mice was proposed to be the action mechanism of HMCEF inhibiting thrombosis and inflammation. All data imply that HMCEF is a novel lead of P-selectin inhibitor.

Protein methionine oxidation augments reperfusion injury in acute ischemic stroke

Reperfusion injury can exacerbate tissue damage in ischemic stroke, but little is known about the mechanisms linking ROS to stroke severity. Here, we tested the hypothesis that protein methionine oxidation potentiates NF-κB activation and contributes to cerebral ischemia/reperfusion injury. We found that overexpression of methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that reverses protein methionine oxidation, attenuated ROS-augmented NF-κB activation in endothelial cells, in part, by protecting against the oxidation of methionine residues in the regulatory domain of calcium/calmodulin-dependent protein kinase II (CaMKII). In a murine model, MsrA deficiency resulted in increased NF-κB activation and neutrophil infiltration, larger infarct volumes, and more severe neurological impairment after transient cerebral ischemia/reperfusion injury. This phenotype was prevented by inhibition of NF-κB or CaMKII. MsrA-deficient mice also exhibited enhanced leukocyte rolling and upregulation of E-selectin, an endothelial NF-κB-dependent adhesion molecule known to contribute to neurovascular inflammation in ischemic stroke. Finally, bone marrow transplantation experiments demonstrated that the neuroprotective effect was mediated by MsrA expressed in nonhematopoietic cells. These findings suggest that protein methionine oxidation in nonmyeloid cells is a key mechanism of postischemic oxidative injury mediated by NF-κB activation, leading to neutrophil recruitment and neurovascular inflammation in acute ischemic stroke.