Aortic Endothelial Injury Research Articles

Hyperglycemia-induced STING signaling activation leads to aortic endothelial injury in diabetes

Hyperglycaemia-induced endothelial dysfunction is a key factor in the pathogenesis of diabetic microangiopathy and macroangiopathy. STING, which is a newly discovered regulator of innate immunity, has also been reported to play an important role in various metabolic diseases. However, the role of STING in diabetes-induced endothelial cell dysfunction is unknown. In this study, we established a diabetic macroangiopathy mouse model by streptozotocin (STZ) injection combined with high-fat diet (HFD) feeding and a glucotoxicity cell model in high glucose (HG)-treated rat aortic endothelial cells (RAECs). We found that STING expression was specifically increased in the endothelial cells of diabetic arteries, as well as in HG-treated RAECs. Moreover, genetic deletion of STING significantly ameliorated diabetes-induced endothelial cell dysfunction and apoptosis in vivo. Likewise, STING inhibition by C-176 reversed HG-induced migration dysfunction and apoptosis in RAECs, whereas STING activation by DMXAA resulted in migration dysfunction and apoptosis. Mechanistically, hyperglycaemia-induced oxidative stress promoted endothelial mitochondrial dysfunction and mtDNA release, which subsequently activated the cGAS-STING system and the cGAS-STING-dependent IRF3/NF-kB pathway, ultimately resulting in inflammation and apoptosis. In conclusion, our study identified a novel role of STING in diabetes-induced aortic endothelial cell injury and suggested that STING inhibition was a potential new therapeutic strategy for the treatment of diabetic macroangiopathy.3DZkNh_P7BQbJb1WXuwa3RVideo

DBDPE upregulates NOD-like receptor signaling to induce NLRP3 inflammasome-mediated HAECs pyroptosis

Decabromodiphenyl ethane (DBDPE), a typical new brominated flame retardant (BFR), is a widespread new pollutant in the environment. Several studies and our previous studies have found that DBDPE can cause aortic endothelial injury and aortic endothelial cell pyroptosis, whereas the molecular mechanism involved has not been elucidated. In this study, we exposed human aortic endothelial cells (HAECs) to 25 μmol/L of DBDPE and analyzed the gene expression profiles by Affymetrix PrimeView™ Human Gene Expression Chip. The results showed that 886 genes were differentially expressed in the DBDPE exposure group. Enrichment analyses revealed that differentially expressed genes were mainly enriched in the inflammatory response and NOD-like receptor signal pathway. Gene-gene functional interaction analyses and crossover genes and pathways analyses found that the NOD-like receptor signal pathway may be involved in regulating NLRP3 and IL-18. We found that NOD2 cannot interact with NLRP3 directly through an immunoprecipitation experiment. Thus, we construct the RIPK2 knockdown HAECs cell line to repress the NOD-like receptor signaling and further study the mechanism of DBDPE-activated NLRP3 inflammasome to induce HAECs pyroptosis. The results showed that RIPK2 knockdown could repress DBDPE-induced NOD-like receptor signaling pathway upregulation, inhibit NLRP3 inflammasome activation, and decrease HAECs pyroptosis. In addition, RIPK2 knockdown decreased the ROS generation in HAECs induced by DBDPE. And NAC pretreated HAECs inhibited DBDPE-induced NLRP3 inflammasome activation and HAECs pyroptosis. These results demonstrated that DBDPE upregulated NOD-like receptor signaling to induce ROS generation and, in turn, activated NLRP3 inflammasome, leading to HAECs pyroptosis.

Tgfβ1-Cthrc1 Signaling Plays an Important Role in the Short-Term Reparative Response to Heart Valve Endothelial Injury.

Aortic valve disease is a common worldwide health burden with limited treatment options. Studies have shown that the valve endothelium is critical for structure-function relationships, and disease is associated with its dysfunction, damage, or injury. Therefore, therapeutic targets to maintain a healthy endothelium or repair damaged endothelial cells could hold promise. In this current study, we utilize a surgical mouse model of heart valve endothelial cell injury to study the short-term response at molecular and cellular levels. The goal is to determine if the native heart valve exhibits a reparative response to injury and identify the mechanisms underlying this process. Approach and Results: Mild aortic valve endothelial injury and abrogated function was evoked by inserting a guidewire down the carotid artery of young (3 months) and aging (16-18 months) wild-type mice. Short-term cellular responses were examined at 6 hours, 48 hours, and 4 weeks following injury, whereas molecular profiles were determined after 48 hours by RNA-sequencing. Within 48 hours following endothelial injury, young wild-type mice restore endothelial barrier function in association with increased cell proliferation, and upregulation of transforming growth factor beta 1 (Tgfβ1) and the glycoprotein, collagen triple helix repeat containing 1 (Cthrc1). Interestingly, this beneficial response to injury was not observed in aging mice with known underlying endothelial dysfunction. Data from this study suggests that the healthy valve has the capacity to respond to mild endothelial injury, which in short term has beneficial effects on restoring endothelial barrier function through acute activation of the Tgfβ1-Cthrc1 signaling axis and cell proliferation.

130. Tranexamic acid use is associated with reduced intraoperative blood loss during spine surgery in Marfan syndrome

<h3>BACKGROUND CONTEXT</h3> Sixty percent of patients with Marfan syndrome (MFS) have scoliosis, of which up to 50% will typically require surgical intervention. Chief among surgical concerns in MFS patients undergoing scoliosis correction is the increased risk for intraoperative bleeding due to hemostatic deviations secondary to aortic dilatation, rheological disturbances, endothelial injury, and abnormal levels of clotting factors. Tranexamic acid (TXA) is an anti-fibrinolytic agent that has been demonstrated to reduce blood loss secondary to traumatic injury or surgical intervention, and the subsequent need for transfusion. However, the efficacy of TXA in connective tissue disorders, like MFS, is controversial given the interaction between the clotting cascade and the endothelium of the vasculature. To our knowledge, no other study has previously reported on the utility of TXA in the surgical management of MFS-associated scoliosis. <h3>PURPOSE</h3> The objective of this study was to assess the effect of TXA on intraoperative blood requirements in MFS patients undergoing spinal fusion. <h3>STUDY DESIGN/SETTING</h3> Retrospective review, single institution. <h3>PATIENT SAMPLE</h3> Administrative databases were queried for patients with MFS who underwent spinal fusion for scoliosis between 2000 and 2020 by one surgeon. We excluded operations spanning <3 vertebral levels, along with those related to growing rods (insertion or distraction) or postoperative infection. Sixty-one patients with MFS met inclusion criteria, of whom 23 were treated with TXA and 38 were not. <h3>OUTCOME MEASURES</h3> The following outcomes were assessed and compared between MFS patients treated with and without TXA during spinal fusion: estimated intraoperative blood loss and allogenic blood transfusion requirements. <h3>Methods</h3> The individual charts (including operative and anesthesia notes) of all patients were personally reviewed by study team members to identify MFS patients who received TXA during spinal fusion and their surgical outcomes. Statistical analysis was performed to compare demographic variables and surgical outcomes – using chi-square or t tests, as appropriate. A p-value of < 0.05 was considered significant. <h3>Results</h3> There was no significant difference in patient age, gender, curvature severity, or number of levels fused between the groups. Patients with MFS who were treated with TXA experienced significantly less intraoperative blood loss (625 ± 229 ml, p = 0.008) compared to those who were not. Likewise, we detected a significant difference in total quantity of transfused allogeneic blood products (1.3 ± 0.5, p = 0.013), though there was no difference in transfusion rates between each group (p = 0.317). <h3>Conclusions</h3> We demonstrate the efficacy of TXA in hemostasis during surgical treatment of MFS-associated scoliosis. Our study suggests that the vascular effects secondary to connective tissue deficiency in MFS does not interfere with TXA mechanism of action. <h3>FDA DEVICE/DRUG STATUS</h3> Unavailable from authors at time of publication. Tranexamic acid: not approved for this indication.

The effect of olmesartan on aortic intimal thickening after balloon injury through Apelin/APJ

PurposeRestenosis is the main complication after percutaneous coronary intervention. The proliferation of new intima contributes to the process. In this study, we aimed to explore the effect of olmesartan on intimal thickening after balloon injury and possible mechanism. MethodsAortic endothelial denudation model was made by a 2F balloon catheter. Thirty-six rats were randomly allocated into three groups: Control (n = 12) Surgery (n = 12, received vascular balloon injury) and Olmesartan (n = 12, received 3 mg.kg-1.d-1olmesartan after injury). Fourteen and 28 days after injury, HE staining was used to assess the aortic endothelial injury. Radioimmunological method was used to examine the level of angiotensin II (Ang II). Western blotting and reverse transcription polymerse chain reaction (RT-PCR) were employed to detect the protein and mRNA level of Apelin/APJ. ResultsAfter vascular balloon injury, the proliferation of vascular smooth muscle cells and the intimal thickening were increased. The mRNA and protein level of Ang II, AT1, Apelin and APJ mRNA were promoted by vascular balloon injury. Olmesartan decreased the proliferation of vascular smooth muscle cells and the intimal thickening. Olmesartan decreased the expression of Ang II and AT1, but further increased the expression of Apelin and APJ. Balloon injury also induced the activation of Extracellular signal-regulated kinase (ERK) signaling and olmesartan decreased the effect. ConclusionOlmesartan inhibits the intimal thickening through activating Apelin/APJ and inhibiting AngII-AT1 and ERK pathway.

β-hydroxybutyrate antagonizes aortic endothelial injury by promoting generation of VEGF in diabetic rats

Endothelial injury is regarded as the initial pathological process in diabetic vascular diseases, but effective therapy has not yet been identified. Although β-hydroxybutyrate plays various protective roles in the cardiovascular system, its ability to antagonize diabetic endothelial injury is unclear. β-hydroxybutyrate reportedly causes histone H3K9 β-hydroxybutyrylation (H3K9bhb), which activates gene expression; however, there has been no report regarding the role of H3K9bhb in up-regulation of vascular endothelial growth factor (VEGF), a crucial factor in endothelial integrity and function. Here, male Sprague-Dawley rats were intraperitoneally injected with streptozotocin to induce diabetes, and then treated with different concentrations of β-hydroxybutyrate. After 10 weeks, body weight, blood glucose, morphological changes and serum nitric oxide concentration were examined. Moreover, the mRNA expression level, protein content and distribution of VEGF in the aorta were investigated, as were total protein β-hydroxybutyrylation and H3K9bhb contents. The results showed injury of aortic endothelium, along with reductions of the concentration of nitric oxide and generation of VEGF in diabetic rats. However, β-hydroxybutyrate treatment attenuated diabetic injury of the endothelium and up-regulated the generation of VEGF. Furthermore, β-hydroxybutyrate treatment caused marked total protein β-hydroxybutyrylation and significant elevation of H3K9bhb content in the aorta of diabetic rats. The ability of β-hydroxybutyrate to protect against diabetic injury of the aortic endothelium was greatest for its intermediate concentration. In conclusion, moderately elevated β-hydroxybutyrate could antagonize aortic endothelial injury, potentially by causing H3K9bhb to promote generation of VEGF in diabetic rats.

The Role of Angiotensin II Type 1 Receptor-Activating Antibodies in Vascular Inflammation

Background: Studies demonstrated the autoantiboies against angiotension II type 1 receptor (AT1-AAs) could induce vascular endothelial dysfunction. Our objective is to investigate the effect of AT1-AAs on atherosclerosis. Methods: AT1-AAs were purified from sera of patients with primary hypertension. Thirty-six New Zealand white rabbits were underwent balloon-induced abdominal aortic endothelial injury and fed an atherogenic diet for 6 weeks and were randomly divided into six groups with different drugs for 4 weeks. The levels of AT1-AAs, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in different stage were detected by ELISA. The abdominal aortas of rabbits were stained with hematoxylin and eosin. The expression of matrix metalloproteinases-2 (MMP-2) in aortic tissue was detected by Western blotting. Results: The levels of TNF-α in the eighth week (0.17 ± 0.04, 0.34 ± 0.08) and in the tenth week (0.23 ± 0.04, 0.54 ± 0.11) were significantly higher than that at the beginning of test (0.04 ± 0.03, 0.08 ± 0.02) in the group of AT1-AAs with low-dose and high-dose (P < 0.05). The level of IL-6 stimulated by high dose AT1-AAs was higher in the tenth week (0.42 ± 0.08) than that at the beginning of test (0.04 ± 0.01, P < 0.05). The relative area of plaque was significantly (P < 0.05) increased in group of AT1-AAs with low-dose (46.99% ± 13.06%) and high-dose (66.11% ± 19.67%) compared with other groups. The expression of MMP-2 was significantly higher (P < 0.05) in group AT1-AAs with low dose (0.42 ± 0.03) and high dose (0.54 ± 0.04) than that in other groups. Conclusion: The results showed that the AT1-AAs could aggravate the inflammatory reaction and the plaque formation.

Aqueous extract of Houttuynia cordata ameliorates aortic endothelial injury during hyperlipidemia via FoxO1 and p38 MAPK pathway

Abstract Increasing evidence demonstrates that hyperlipidemia plays a causal role in the development of cardiovascular diseases (CVDs) due to endothelial dysfunction. Houttuynia cordata aqueous extract (HAE), using as both medicine and food, whose effect and mechanism were investigated in endothelial dysfunction. In vivo, it profoundly attenuated hyperlipidemia-induced accumulation of serum metabolites, which in turn contributed to alleviating morphologic and functional damage in vascular endothelium. Moreover, the decrease expression of FoxO1/PGC-1α and mitochondrial complexes in thoracic vessels were ameliorated by HAE administration. Through in vitro cultures, consistently, the results showed that HAE predominantly activated PGC-1α for mitochondrial biogenesis via enhancing FoxO1 expression. Additionally, silencing of FoxO1 remarkably abolished the ability of HAE to augment PGC-1α expression, implying the imperative role of FoxO1 during protection. Besides, the anti-inflammation was mainly mediated via p38 MAPK pathway. Briefly, our study demonstrated that HAE ameliorated hyperlipidemia-induced endothelial injury via upregulating FoxO1/PGC-1α and suppressing p38 MAPK.

Platelet microparticles contribute to aortic vascular endothelial injury in diabetes via the mTORC1 pathway.

Platelet microparticles (PMPs) are closely associated with diabetic macrovascular complications. The present study aimed to investigate the effects of PMPs in diabetes on aortic vascular endothelial injury and to explore the underlying mechanisms. Peritoneal injection of streptozotocin was used to generate a diabetic rat model in vivo, and human umbilical vein endothelial cells (HUVECs) treated with PMPs were used in vitro. PMP levels in the circulation and aorta tissues were time-dependently increased in streptozotocin-induced diabetic rats at weeks 4, 8, and 12 (P < 0.05). Aspirin significantly inhibited the PMP levels at each time point (P < 0.05). In diabetic rats, the endothelial nitric oxide levels were decreased significantly combined with increased endothelial permeability. PMPs were internalized by HUVECs and primarily accumulated around the nuclei. PMPs inhibited endothelial nitric oxide levels to about 50% and caused approximately twofold increase in reactive oxygen species production. Furthermore, PMPs significantly decreased the endothelial glycocalyx area and expression levels of glypican-1 and occludin (P < 0.05). Interestingly, the PMP-induced endothelial injuries were prevented by raptor siRNA and rapamycin. In conclusion, increased PMPs levels contribute to aortic vascular endothelial injuries in diabetes through activating the mTORC1 pathway.

Endothelial Regeneration of Large Vessels Is a Biphasic Process Driven by Local Cells with Distinct Proliferative Capacities.

The cellular and mechanistic bases underlying endothelial regeneration of adult large vessels have proven challenging to study. Using a reproducible invivo aortic endothelial injury model, we characterized cellular dynamics underlying the regenerative process through a combination of multi-color lineage tracing, parabiosis, and single-cell transcriptomics. We found that regeneration is a biphasic process driven by distinct populations arising from differentiated endothelial cells. The majority of cells immediately adjacent to the injury site re-enter the cell cycle during the initial damage response, with a second phase driven by a highly proliferative subpopulation. Endothelial regeneration requires activation of stress response genes including Atf3, and aged aortas compromised in their reparative capacity express less Atf3. Deletion of Atf3 reduced endothelial proliferation and compromised the regeneration. These findings provide important insights into cellular dynamics and mechanisms that drive responses to large vessel injury.

Exercise intervention attenuates hyperhomocysteinemia-induced aortic endothelial oxidative injury by regulating SIRT1 through mitigating NADPH oxidase/LOX-1 signaling

Coronary artery disease (CAD) is a critical cardiovascular disease and a cause of high morbidity and mortality in this world. Hyperhomocysteinemia (HHcy) has been suggested as a risk factor for CAD. In addition, SIRT1 (sirtuin 1) has been reported to play a protective role in a variety of diseases, especially in the cardiovascular system. The main purpose of this study was to investigate the effects of exercise training on apoptosis and inflammation in HHcy animals. We also tested whether exercise protected against Hhcy-induced dysfunction of endothelium through modulation of SIRT1. C57BL mice (8 in each group) were fed with or without 1% L-methionine (w/w) in water for 4 months to induce HHcy. We found that Hhcy repressed SIRT1 and AMPK expression and increased NADPH oxidase activity. Plasma MDA, endothelium LOX-1 and p-p38 were up-regulated by Hhcy induction. NF-κB and it downstream molecules were activated under Hhcy situation, thereby promoting pro-inflammatory responses. Moreover, we also reported that Hhcy caused endothelium apoptosis involving Akt inhibition and mitochondria-dependent apoptotic pathways. Exercise training significantly protected against endothelium from Hhcy caused oxidative injuries. In addition, EX527 (SIRT1 inhibitor) reduced the therapeutic effects by exercise. Our results had indicated that exercise training prevent the development of atherosclerosis through SIRT1 activation and oxidative stress inhibition under Hhcy situation.

Protection from cigarette smoke‐induced vascular injury by recombinant human relaxin‐2 (serelaxin)

Smoking is regarded as a major risk factor for the development of cardiovascular diseases (CVD). This study investigates whether serelaxin (RLX, recombinant human relaxin‐2) endowed with promising therapeutic properties in CVD, can be credited of a protective effect against cigarette smoke (CS)‐induced vascular damage and dysfunction. Guinea pigs exposed daily to CS for 8 weeks were treated with vehicle or RLX, delivered by osmotic pumps at daily doses of 1 or 10 μg. Controls were non‐smoking animals. Other studies were performed on primary guinea pig aortic endothelial (GPAE) cells, challenged with CS extracts (CSE) in the absence and presence of 100 ng/ml (17 nmol/l) RLX. In aortic specimens from CS‐exposed guinea pigs, both the contractile and the relaxant responses to phenylephrine and acetylcholine, respectively, were significantly reduced in amplitude and delayed, in keeping with the observed adverse remodelling of the aortic wall, endothelial injury and endothelial nitric oxide synthase (eNOS) down‐regulation. RLX at both doses maintained the aortic contractile and relaxant responses to a control‐like pattern and counteracted aortic wall remodelling and endothelial derangement. The experiments with GPAE cells showed that CSE significantly decreased cell viability and eNOS expression and promoted apoptosis by sparkling oxygen free radical‐related cytotoxicity, while RLX counterbalanced the adverse effects of CSE. These findings demonstrate that RLX is capable of counteracting CS‐mediated vascular damage and dysfunction by reducing oxidative stress, thus adding a tile to the growing mosaic of the beneficial effects of RLX in CVD.

Early in vivo discrimination of vulnerable atherosclerotic plaques that disrupt: A serial MRI study

Background and aimsMRI has been validated as a suitable imaging modality for in vivo, non-invasive detection of atherosclerosis and has provided quantitative predictors of high-risk plaque. Here, we apply serial MRI to monitor the natural progression of plaques over a 3-month period in a rabbit model of atherothrombosis to determine differences over time between plaques that ultimately disrupt to form a luminal mural thrombus and plaques that remain stable. MethodsAtherosclerotic plaques were induced in 12 male New Zealand White (NZW) rabbits by aortic endothelial injury and a 1% cholesterol diet. The rabbits were imaged 5 times: at baseline, 1, 2, and 3 months, and 48hr after pharmacological triggering for plaque disruption. ResultsStarting at 2 months, plaques that disrupted after triggering exhibited a higher remodeling ratio (RR, 1.05 ± 0.11 vs 0.97 ± 0.10, p = 0.0002) and a larger vessel wall area (VWA, 6.99 ± 1.54 mm2 vs 6.30 ± 1.37 mm2, p = 0.0072) than the stable non-disrupted plaques. The same trends were observed at 3 months: plaques that disrupted had a higher RR (1.04 ± 0.02 vs 0.99 ± 0.01, p = 0.0209), VWA (8.19 ± 2.69 mm2 vs 6.81 ± 1.60 mm2, p = 0.0001), and increased gadolinium uptake (75.51 ± 13.77% for disrupted vs 31.02 ± 6.45% for non-disrupted, p = 0.0022). ConclusionsMR images of plaques that disrupted revealed larger VWAs, RRs, and increased gadolinium uptake at 2 months and continued progression of these vulnerable features between 2 and 3 months. Non-disrupted plaques had an independent history without these hallmarks of vulnerability. Our results show that MRI can provide early detection of plaques at a higher-risk for luminal thrombosis.

ORAL ADMINISTRATION OF DOXYCYCLINE PREVENTS VULNERABLE PLAQUES FROM RUPTURE INDEPENDENT OF SERUM LIPID LEVELS (AN ANIMAL EXPERIMENT WITH RABBITS)

ObjectivesChronic inflammatory responses have been implicated in the process of atherosclerosis. Doxycycline, as a broad spectrum antibiotic, has also proven effective in inhibiting MMP. The aim of this study was...

A novel atherogenic epitope from Mycobacterium tuberculosis heat shock protein 65 enhances atherosclerosis in rabbit and LDL receptor-deficient mice

Previous studies have established that Mycobacterium tuberculosis heat shock protein 65 (mHSP65) plays an important role in immune-associated diseases as an autoimmune factor. Some overlapping epitopes of mHSP65 may serve as initiators of both atherosclerosis and other autoimmune-associated diseases. In the present study, atherosclerosis was significantly enhanced in high-cholesterol diet (HCD)-fed New Zealand white rabbits immunized with mHSP65(91-105) compared with PBS-immunized or BSA-immunized rabbits. Immunizing wild-type C57BL/6J mice with mHSP65(91-105) induced the aortic endothelial injury. Although western blot demonstrated that specific antibodies against mHSP65(91-105) can cross-react with recombinant human heat shock protein 60, specific antibodies against mHSP65(91-105) had no direct effects on HUVECs in vitro. Laser scanning confocal microscopy showed that mHSP65(91-105) localized in the cytoplasm of HUVECs, even when HUVECs were heat shocked at 42°C. mHSP65(91-105)-specific splenic cells secreted more IFN-γ than controls. Also, adoptive transfer of mHSP65(91-105)-specific splenic cells can accelerate atherosclerosis in ldlr( -/- ) mice. We can conclude that the (auto)immune response to mHSP65(91-105) accelerates atherosclerosis in animal models, and that the response of Th1 plays an important role in this progress.

Chinese medicine tongxinluo significantly lowers serum lipid levels and stabilizes vulnerable plaques in a rabbit model

Relevance to ethnopharmacologyTongxinluo capsule is a compound preparation formulated on the basis of the meridian theory of traditional Chinese medicine and is officially approved for the treatment of angina pectoris and ischemic stroke in China. ObjectivesTo test the hypothesis that the Chinese traditional medicine tongxinluo in capsule form has similar effects as simvastatin in lowering serum lipid levels and stabilizing vulnerable plaques. Materials and methodsThirty New Zealand white rabbits underwent balloon-induced abdominal aortic endothelial injury and were fed a diet of 1% cholesterol for 8 weeks. The rabbits were then randomly divided into three groups (n=10 each) for daily doses of tongxinluo capsule (1g/kg), simvastatin (5mg/kg) or no drugs for 12 weeks. At the end of week 20, plaque rupture was induced by pharmacological triggering. Serological, ultrasonographic, pathologic, immunohistochemical, and gene expression studies were performed. ResultsThe incidence of plaque rupture with tongxinluo and simvastatin treatment was significantly lower than that with control treatment (0% for both drug treatments vs. 56.0%; P<0.05). Values of serum lipid profile, inflammatory markers, and pathological and immunohistological assays were significantly improved in the tongxinluo- and simvastatin-treated groups than in the control group. The simvastatin-treated group showed lower serum lipid levels than the tongxinluo-treated group. ConclusionsTreatment with the Chinese medicine tongxinluo was as effective as simvastatin in lowering serum lipid levels, inhibiting plaque inflammation and preventing vulnerable plaques from rupture and may provide an alternative therapy for atherosclerosis.

Dominant‐negative mutation of monocyte chemoattractant protein‐1 prevents vulnerable plaques from rupture in rabbits independent of serum lipid levels

Active inflammation is an important feature of vulnerable plaques, and monocyte chemoattractant protein-1 (MCP-1) is a key chemokine that promotes monocyte–endothelium binding and initiates inflammation. We aimed to determine whether dominant-negative mutation of MCP-1 could reverse atherosclerotic lesion progression and prevent vulnerable plaques from rupture regardless of serum lipid levels. The mutant MCP-1 was produced by deletion of the N-terminal amino acids 2 to 8 (7ND), and a eukaryotic expression vector plRES-EGFP-7ND was constructed. The transwell chamber was used to assay chemotaxis of monocytes in vitro. Thirty New Zealand white rabbits underwent balloon-induced abdominal aortic endothelial injury and were randomly divided into control group without gene intervention (group A, n = 10), plRES-EGFP-7ND treatment group (group B, n = 10) and empty vector treatment group (group C, n = 10). All rabbits were fed a diet of 1% cholesterol for 8 weeks, and then group A rabbits were killed, whereas groups B and C rabbits received an intramuscular injection of plRES-EGFP-7ND and an empty lipofectamine, respectively, and remained on a high cholesterol diet for 4 weeks. At the end of week 12, groups B and C rabbits underwent pharmacological triggering by injection with Chinese Russellis viper venom and histamine. Serum lipids and inflammatory markers were measured, and high-frequency ultra-sonography and intravascular ultrasound imaging were performed. Immunohistochemistry and RT-PCR were used to examine expression of inflammatory markers in the plaques. In vitro transfection of plRES-EGFP-7ND resulted in a significant inhibition of monocyte chemotaxis (P < 0.05) and in vivo transfection of plRES-EGFP-7ND significantly increased the thickness of the fibrous caps and decreased plaque vulnerability index. The incidence of plaque rupture in group B was 0% as compared with 56% in the empty vector treatment group (P< 0.05). The serum levels and expression of inflammatory markers were significantly reduced in group B. In conclusion, PIRES-EGFP-7ND transfection effectively inhibits plaque inflammation, reverses plaque progression and prevents vulnerable plaques from rupture. These therapeutic effects are independent of serum lipid levels and demonstrate that inhibition of plaque inflammation alone without lipid lowering can stabilize vulnerable plaques.

Targeted vascular delivery of antisense molecules using intravenous microbubbles

Perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles bind the antisense to the c-myc protooncogene (anti-c-myc) which prevents neointimal hyperplasia following vascular endothelial injury. The microbubbles also adhere to sites of damaged vascular endothelium and thus may be a method of systemically targeting delivery of anti-c-myc. Laser scanning microscopy was performed on the aorta of 10 mice (five which were complement depleted) that received intravenous FITC-PESDA following aortic endothelial injury. C-myc expression was quantified following selective intracoronary injury in nine pigs that received intravenous (IV) anti-c-myc bound to PESDA. Finally, neointimal formation was measured following intracoronary stent deployment in 30 pigs that received either IV anti-c-myc alone or the same dose bound to PESDA. Fluorescent microscopy confirmed selective PESDA microbubble adherence to aortic endothelium in all mice with aortic injury. This binding was nearly abolished when serum complement was depleted prior to injury. C-myc expression at the site of coronary endothelial injury was significantly lower in pigs treated with systemic anti-c-myc bound to PESDA. There was a 33% reduction in % stenosis and a 28% reduction in intimal area at 45 days post-stent deployment in pigs that received IV antisense plus PESDA. The stent margins also had reduced neointimal formation. Systemic administration of anti-c-myc bound to PESDA microbubbles may be a good method for preventing coronary neointimal formation within and around implanted stents.

Photosensitizer delivery to vulnerable atherosclerotic plaque: comparison of macrophage-targeted conjugate versus free chlorine(e6)

We have previously shown that a conjugate (MA-ce6) between maleylated serum albumin and the photosensitizer chlorin(e6) (ce6) is targeted in vitro to macrophages via class A scavenger receptors. We now report on the ability of this conjugate to localize in macrophage-rich atherosclerotic plaques in vivo. Both the conjugate and the free photosensitizer ce6 are studied after injection into New Zealand White rabbits that are rendered atherosclerotic by a combination of aortic endothelial injury and cholesterol feeding into normal rabbits. Rabbits are sacrificed at 6 and 24 h after injection and intravascular fluorescence spectroscopy is carried out by fiber-based fluorimetry in intact blood-filled arteries. Surface spectrofluorimetry of numbered excised aortic segments together with injured and normal iliac arteries is carried out, and quantified ce6 content by subsequent extraction and quantitative fluorescence determination of the arterial segments and also of nontarget organs. There is good agreement between the various techniques for quantifying ce6 localization, and high contrast between arteries from atherosclerotic and normal rabbits is obtained. Fluorescence correlates with the highest burden of plaque in the aorta and the injured iliac artery. The highest accumulation in plaques is obtained using MA-ce6 at 24 h. Free ce6 gives better accumulation at 6 h compared to 24 h. The liver, spleen, lung, and gall bladder have the highest uptake in nontarget organs. Macrophage-targeted photosensitizer conjugates may have applications in both detecting and treating inflamed vulnerable plaque.

Aortic endothelial cell von Willebrand factor content, and circulating plasminogen activator inhibitor-1 are increased, but expression of endothelial leukocyte adhesion molecules is unchanged in insulin-dependent diabetic BB rats

Endothelial cell injury has been implicated in the increased incidence of vascular disease associated with diabetes mellitus. In diabetic humans, elevated plasma von Willebrand Factor (vWF) has been interpreted as an indication of endothelial damage. In contrast, in an animal model of inherited insulin-dependent diabetes, the bio-breeding (BB) rat, plasma vWF levels did not differ from those in age-matched control rats during the first 7 months of diabetes although morphological evidence of mild aortic endothelial alteration or injury was observed. In the present study efforts have been made to define the endothelial alterations in BB diabetic rats compared to controls more precisely over this time period. Thus, adhesion molecules: intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1(VCAM-1) were evaluated by in situ immunohistochemistry, vWF content was determined by biochemical analysis of aortic extracts and by quantitative immunohistochemistry, plasma vWF levels were measured by ELISA and vWF mRNA by RNAse protection assay. Neither age nor diabetic state significantly affected either the expression of adhesion molecules, or the levels of circulating vWF. Endothelial vWF content was significantly increased in the diabetic vessels, as observed by both approaches but the vWF mRNA content was not different from that in control vessels. Plasma plasminogen activator inhibitor (PAI-1) activity was significantly increased in diabetic animals. In conclusion, endothelial alterations in BB rats associated with diabetes, together with the raised plasma PAI-1 levels, promote the thrombogenic potential of the vessel wall, and are consistent with an increased risk for vascular disease.