Cilostazol inhibits cytokine-induced nuclear factor-kappaB activation via AMP-activated protein kinase activation in vascular endothelial cells

SIRT7 knockdown promotes gemcitabine sensitivity of pancreatic cancer cell via upregulation of GLUT3 expression

Gemcitabine serves as a first-line chemotherapeutic treatment for pancreatic cancer (PC), but it is prone to rapid drug resistance. Increasing the sensitivity of PC to gemcitabine has long been a focus of research. Fasting interventions may augment the effects of chemotherapy and present new options. SIRT7 is known to link metabolism with various cellular processes through post-translational modifications. We found upregulation of SIRT7 in PC cells is associated with poor prognosis and gemcitabine resistance. Cross-analysis of RNA-seq and ATAC-seq data suggested that GLUT3 might be a downstream target gene of SIRT7. Subsequent investigations demonstrated that SIRT7 directly interacts with the enhancer region of GLUT3 to desuccinylate H3K122. Our group's another study revealed that GLUT3 can transport gemcitabine in breast cancer cells. Here, we found GLUT3 KD reduces the sensitivity of PC cells to gemcitabine, and SIRT7 KD-associated gemcitabine-sensitizing could be reversed by GLUT3 KD. While fasting mimicking induced upregulation of SIRT7 expression in PC cells, knocking down SIRT7 enhanced sensitivity to gemcitabine through upregulating GLUT3 expression. We further confirmed the effect of SIRT7 deficiency on the sensitivity of gemcitabine under fasting conditions using a mouse xenograft model. In summary, our study demonstrates that SIRT7 can regulate GLUT3 expression by binding to its enhancer and altering H3K122 succinylation levels, thus affecting gemcitabine sensitivity in PC cells. Additionally, combining SIRT7 knockdown with fasting may improve the efficacy of gemcitabine. This unveils a novel mechanism by which SIRT7 influences gemcitabine sensitivity in PC and offer innovative strategies for clinical combination therapy with gemcitabine.

Advances in immunomodulatory strategies for host-directed therapies in combating tuberculosis

Tuberculosis (TB) maintains its infamous status regarding its detrimental effect on global health, causing the highest mortality by a single infectious agent. The presence of resistance and immune compromising disease favours the disease in maintaining its footing in the health care burden despite various anti-TB drugs used to fight it. Main factors contributing to resistance and difficulty in treating disease include prolonged treatment duration (at least 6 months) and severe toxicity, which further leads to patient non-compliance, and thus a ripple effect leading to therapeutic non-efficacy. The efficacy of new regimens demonstrates that targeting host factors concomitantly with the Mycobacterium tuberculosis (M.tb) strain is urgently required. Due to the huge expenses and time required of up to 20 years for new drug research and development, drug repurposing may be the most economical, circumspective, and conveniently faster journey to embark on. Host-directed therapy (HDT) will dampen the burden of the disease by acting as an immunomodulator, allowing it to defend the body against antibiotic-resistant pathogens whilst minimizing the possibility of developing new resistance to susceptible drugs. Repurposed drugs in TB act as host-directed therapies, acclimatizing the host immune cell to the presence of TB, improving its antimicrobial activity and time taken to get rid of the disease, whilst minimizing inflammation and tissue damage. In this review, we, therefore, explore possible immunomodulatory targets, HDT immunomodulatory agents, and their ability to improve clinical outcomes whilst minimizing the risk of drug resistance, through various pathway targeting and treatment duration reduction.

Effects of cilostazol, a Phosphodiesterase-3 inhibitor, on kidney function and redox imbalance in acute kidney injury caused by Bothrops alternatus venom

The mechanisms of pathogenesis of acute kidney injury (AKI) in snakebites is multifactorial and involves hemodynamic disturbances, with release of free radical causing cytotoxic effects. The phosphodiesterase-3 (PDE3) inhibitor, Cilostazol, has been reported to provide protection against renal oxidative stress.

OBJECTIVE

We evaluated the protective effects of cilostazol against Bothrops alternatus snake venom (BaV)-induced nephrotoxicity.

METHODS

Wistar rat kidneys (n = 6, 260-300 g) were isolated and perfused with Krebs-Henseleit solution containing 6 g/100 mL of bovine serum albumin. After 30 min, the kidneys were perfused with BaV to a final concentration of 1 and 3 μg/mL, and subsequently evaluated for perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), and percentage of electrolyte tubular sodium and chloride transport (%TNa⁺, %TCl^-). Oxidative stress and renal histological analyses were performed.

RESULTS

BaV caused a reduction in all the evaluated renal parameters (PP, RVR, GFR, UF, %TNa⁺, and %TCl^-). Although only the effects on PP and UF were reversed with cilostazol treatment, the decrease in the malondialdehyde levels, without changes in glutathione levels, further reduced the venom-induced renal tissue changes.

CONCLUSION

Our data suggest that PDE3 is involved in BaV-induced nephrotoxicity, as cilostazol administration significantly ameliorated these effects.

Cilostazol: a Review of Basic Mechanisms and Clinical Uses

Primarily used in the treatment of intermittent claudication, cilostazol is a 2-oxyquinolone derivative that works through the inhibition of phosphodiesterase III and related increases in cyclic adenosine monophosphate (cAMP) levels. However, cilostazol has been implicated in a number of other basic pathways including the inhibition of adenosine reuptake, the inhibition of multidrug resistance protein 4, among others. It has been observed to exhibit antiplatelet, antiproliferative, vasodilatory, and ischemic-reperfusion protective properties. As such, cilostazol has been investigated for clinical use in a variety of settings including intermittent claudication, as an adjunctive for reduction of restenosis after coronary and peripheral endovascular interventions, and in the prevention of secondary stroke, although its widespread implementation for indications other than intermittent claudication has been limited by relatively modest effect sizes and lack of studies in western populations. In this review, we highlight the pleiotropic effects of cilostazol and the evidence for its clinical use.

Endothelium as a Therapeutic Target in Diabetes Mellitus: From Basic Mechanisms to Clinical Practice

Endothelium plays an essential role in human homeostasis by regulating arterial blood pressure, distributing nutrients and hormones as well as providing a smooth surface that modulates coagulation, fibrinolysis and inflammation. Endothelial dysfunction is present in Diabetes Mellitus (DM) and contributes to the development and progression of macrovascular disease, while it is also associated with most of the microvascular complications such as diabetic retinopathy, nephropathy and neuropathy. Hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia are the main factors involved in the pathogenesis of endothelial dysfunction. Regarding antidiabetic medication, metformin, gliclazide, pioglitazone, exenatide and dapagliflozin exert a beneficial effect on Endothelial Function (EF); glimepiride and glibenclamide, dipeptidyl peptidase-4 inhibitors and liraglutide have a neutral effect, while studies examining the effect of insulin analogues, empagliflozin and canagliflozin on EF are limited. In terms of lipid-lowering medication, statins improve EF in subjects with DM, while data from short-term trials suggest that fenofibrate improves EF; ezetimibe also improves EF but further studies are required in people with DM. The effect of acetylsalicylic acid on EF is dose-dependent and lower doses improve EF while higher ones do not. Clopidogrel improves EF, but more studies in subjects with DM are required. Furthermore, angiotensin- converting-enzyme inhibitors /angiotensin II receptor blockers improve EF. Phosphodiesterase type 5 inhibitors improve EF locally in the corpus cavernosum. Finally, cilostazol exerts favorable effect on EF, nevertheless, more data in people with DM are required.

LC-MS/MS method for simultaneous determination of rivaroxaban and metformin in rat plasma: application to pharmacokinetic interaction study

Aim: A reliable, sensitive and simple LC-MS/MS method has been established and validated for the quantitation of rivaroxaban (RIV) and metformin (MET) in rat plasma. Results: The procedure of method validation was conducted according to the guiding principles of EMA and US FDA. At the same time, the method was applied to pharmacokinetic interactions study between RIV and MET for the first time. When RIV and MET coadministered to rats, pharmacokinetic parameters of MET like AUC_(0-t), AUC_(0-∞) and C_max had statistically significant increased. t_max of RIV was prolonged without affecting t_1/2 obviously and C_max was inhibited significantly (p < 0.05) by comparison to the single group. Conclusion: The results indicated that drug-drug interactions occurred when the coadministration of RIV and MET.

Development of a Multicomponent Intervention to Prevent Alzheimer's Disease

Recent advances in vascular risk management have successfully reduced the prevalence of Alzheimer's Disease (AD) in several epidemiologic investigations. It is now widely accepted that cerebrovascular disease is both directly and indirectly involved in AD pathogenesis. Herein, we review the non-pharmacological and pharmacological therapeutic approaches for AD treatment. MIND [Mediterranean and DASH (Dietary Approaches to Stop Hypertension) Intervention for Neurodegenerative Delay] diet is an important dietary treatment for prevention of AD. Multi domain intervention including diet, exercise, cognitive training, and intensive risk managements also prevented cognitive decline in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) study. To confirm these favorable effects of life-style intervention, replica studies are being planned worldwide. Promotion of β-amyloid (Aβ) clearance has emerged as a promising pharmacological approach because insufficient removal of Aβ is more important than excessive Aβ production in the pathogenesis of the majority of AD patients. Most AD brains exhibit accompanying cerebral amyloid angiopathy, and Aβ distribution in cerebral amyloid angiopathy closely corresponds with the intramural periarterial drainage (IPAD) route, emphasizing the importance of Aβ clearance. In view of these facts, promotion of the major vascular-mediated Aβ elimination systems, including capillary transcytosis, the glymphatic system, and IPAD, have emerged as new treatment strategies in AD. In particular, the beneficial effects of cilostazol were shown in several clinical observation studies, and cilostazol facilitated IPAD in a rodent AD model. The COMCID (Cilostazol for prevention of Conversion from MCI to Dementia) trial, evaluating the efficacy of cilostazol for patients with mild cognitive impairment is currently ongoing in Japan. Such therapeutic approaches involving maintenance of cerebrovascular integrity and promotion of vascular-mediated Aβ clearance have the potential to be mainstream treatments for sporadic AD.

Comparison of antiplatelet treatment in patients with clopidogrel nonresponders with or without carriage of CYP2C19 polymorphism

BACKGROUND/AIMS

Several interventions exist for overcoming high platelet reactivity (HPR) on clopidogrel therapy. The goal of this study was to identify strategies that improve inhibition of platelet reactivity in clopidogrel nonresponders with or without loss of function CYP2C19 genotypes, resulting in platelet reactivity similar to that in responders.

METHODS

A total of 376 patients with stenting for coronary artery disease underwent platelet function testing in three centers. Blinded platelet function tests were performed after 75 mg daily clopidogrel treatment for 28 days. In total, 183 nonresponders were genotyped, were randomized to four treatment groups with each treatment lasting approximately 28 days, and underwent repeated measurements of platelet reactivity after treatment.

RESULTS

With 75 mg of daily clopidogrel, nonresponders had significantly higher HPR than did responders (multiple electrode aggregometry [MEA, arbitrary platelet aggregation unit]: mean, 71.4; 95% confidence intervals [CI], 68.6 to 74.3; and mean, 27.5; 95% CI, 26.0 to 28.9, respectively; p < 0.001). Ticagrelor or ticlopidine treatment in nonresponders resulted in platelet reactivity similar to that in responders in intermediate metabolizers (mean, 24.0; 95% CI, 19.6 to 28.4; p > 0.05; and mean, 30.0; 95% CI, 24.7 to 37.5; p > 0.05, respectively) and poor metabolizers (mean, 23.2; 95% CI, 18.0 to 28.3; p > 0.05; and mean, 30.3; 95% CI, 24.5 to 6.0; p > 0.05, respectively). However, in extensive metabolizers, only ticagrelor treatment showed platelet reactivity similar to that in responders (mean, 26.1; 95% CI, 24.1 to 28.0; p > 0.05).

CONCLUSIONS

Among clopidogrel nonresponders with cardiovascular disease on 75 mg daily clopidogrel, ticagrelor resulted in a comparable degree of platelet inhibition in all nonresponders compared with 150 mg daily clopidogrel or triple therapy with clopidogrel and cilostazol, irrespective of phenotype.

Effect of cilostazol in treating diabetes-associated microvascular complications

PURPOSE

Cilostazol (Pletal), a phosphodiesterase-3 inhibitor, was approved in the United States in 1999 to reduce symptoms of intermittent claudication. Cyclic adenosine monophosphate levels increase from inhibition of phosphodiesterase resulting in anti-platelet, anti-inflammatory, and vasodilatory effects. Diabetes mellitus is a chronic disease that causes endothelial and platelet dysfunction leading to both microvascular and macrovascular complications. This mini-review highlights the emerging evidence suggesting benefits of using cilostazol in treating microvascular complications associated with diabetes mellitus.

METHODS

A review of literature was conducted using PubMed and Embase databases focusing on cilostazol use in diabetes mellitus.

RESULTS

Cilostazol demonstrated renoprotective effects in patients with diabetic nephropathy by reducing serum soluble adhesion molecule-1 and monocyte chemoattractant protein-1. Cilostazol's anti-inflammatory actions predictably attenuate glomerular damage from increased leukocyte adherence. Additionally, cilostazol delayed renal dysfunction secondary to type 2 diabetes mellitus as albuminuria was reduced most likely resulting from inhibition of nuclear factor kappa-induced inflammatory and endothelial markers. Cilostazol's anti-inflammatory actions in addition to its vasodilatory actions relieved retinal hypoxia and decreased excessive production of retinal blood vessels suggesting benefit in diabetic retinopathy. Cilostazol did not improve neuropathy symptom scores signifying that it may not be as beneficial in patients with diabetic peripheral neuropathy without diabetic nephropathy or diabetic retinopathy.

CONCLUSIONS

Cilostazol's pleiotropic effects may be beneficial in patients with type 2 diabetes mellitus and diabetic nephropathy. Additional, larger studies need to be conducted to assess the benefits and risks of using cilostazol as an alternative agent in treating patients with diabetic microvascular complications.

Troxerutin protects against diabetic cardiomyopathy through NF‑κB/AKT/IRS1 in a rat model of type 2 diabetes

Troxerutin is a bioflavonoid, which can be used to treat venous disorders, thrombosis and cerebrovascular diseases. Recent studies have demonstrated that it may also be used to prevent edemas. However, it is not known whether troxerutin protects against the cardiomyopathic complications of diabetes. In the present study, a rat model of type 2 diabetes was used to investigate the potential for troxerutin to protect against diabetic cardiomyopathy, through changes to nuclear factor‑κB (NF‑κB) expression. Troxerutin administration significantly reduced heart rate, blood pressure, blood glucose and plasma triglyceride levels across all measured time points. Furthermore, troxerutin significantly reduced reactive oxygen species levels, NF‑κB protein expression, and suppressed the phosphorylated forms of AKT, insulin receptor substrate 1 (IRS1) and c‑Jun N‑terminal kinase (JNK). These results suggested that troxerutin protects against cardiomyopathy via alterations in NF‑κB, AKT and IRS1 signaling, in a rat model of type 2 diabetes.

Protective effects of various ratios of DHA/EPA supplementation on high-fat diet-induced liver damage in mice

Background

A sedentary lifestyle and poor diet are risk factors for the progression of non-alcoholic fatty liver disease. However, the pathogenesis of hepatic lipid accumulation is not completely understood. Therefore, the present study explored the effects of dietary supplementation of various ratios of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on a high-fat diet-induced lipid metabolism disorder and the concurrent liver damage.

Methods

Using high-fat diet-fed C57BL/6 J mice as the animal model, diets of various ratios of DHA/EPA (2:1, 1:1, and 1:2) with an n-6/n-3 ratio of 4:1 were prepared using fish and algae oils enriched in DHA and/or EPA and sunflower seed oils to a small extent instead of the high-fat diet.

Results

Significantly decreased hepatic lipid deposition, body weight, serum lipid profile, inflammatory reactions, lipid peroxidation, and expression of adipogenesis-related proteins and inflammatory factors were observed for mice that were on a diet supplemented with DHA/EPA compared to those in the high-fat control group. The DHA/EPA 1:2 group showed lower serum triglycerides (TG), total cholesterol (TC), and low-density lipoprotein-cholesterol levels, lower SREBP-1C, FAS, and ACC-1 relative mRNA expression, and higher Fra1 mRNA expression, with higher relative mRNA expression of enzymes such as AMPK, PPARα, and HSL observed in the DHA/EPA 1:1 group. Lower liver TC and TG levels and higher superoxide dismutase levels were found in the DHA/EPA 2:1 group. Nonetheless, no other notable effects were observed on the biomarkers mentioned above in the groups treated with DHA/EPA compared with the DHA group.

Conclusions

The results showed that supplementation with a lower DHA/EPA ratio seems to be more effective at alleviating high-fat diet-induced liver damage in mice, and a DHA/EPA ratio of 1:2 mitigated inflammatory risk factors. These effects of n-3 polyunsaturated fatty acids (PUFA) on lipid metabolism may be linked to the upregulation of Fra1 and attenuated activity of c-Jun and c-Fos, thus ultimately reducing the severity of the lipid metabolism disorder and liver damage to some extent.

Cilostazol Can Increase Skin Oxygen Supply Assessed by Transcutaneous Oxygen Pressure Measurement in Type 2 Diabetes With Lower Limb Ischemic Disease: A Randomized Trial

PURPOSE

The purpose of this study was to compare the efficacy and safety of cilostazol versus acetylsalicylic acid (ASA) for amelioration of lower limb ischemia in type 2 diabetes.

DESIGN

Prospective, randomized positive-controlled open clinical trial.

SUBJECTS AND SETTING

Eighty-nine patients with type 2 diabetes mellitus and symptoms of lower limb ischemia (perceptions of coldness of the lower limbs, numbness, intermittent claudication, or pain at rest) present for 6 months or more that had not significantly changed within the past 3 months participated in the study. All subjects had an initial transcutaneous oxygen pressure (TcpO2) of less than 40 mm Hg in the foot when measured in the supine position. Subjects included 46 males and 43 females; their ages ranged from 35 to 80 years.

METHODS

Participants were randomly allocated to 2 groups, one was treated with cilostazol 100 mg taken twice daily (n = 48), and a second group took 100 mg of ASA daily (n = 41) for 8 weeks. Clinical assessment included measurement of transcutaneous oxygenation, and symptoms associated with lower limb ischemia. Blood analyses included a full blood panel, coagulation screen, renal function tests, hepatic function tests, and lipid profiles. All tests were performed at baseline and repeated at 8 weeks.

RESULTS

Age, duration of diabetes, diabetic complications, lower limb ischemic symptoms, TcpO2, and smoking status did not differ between the 2 groups. In contrast, TcpO2 significantly improved from 37.1 ± 11.9 mm Hg to 42.0 ± 9.7 mm Hg in the cilostazol-treated group (P < .05), whereas no significant change was observed in the ASA-treated group (P > .05). Ischemic symptoms such as intermittent claudication (P = .009), perception of limb coldness (P = .008), and pain at rest (P = .017) showed greater improvement in the cilostazol-treated group when compared to subjects treated with ASA. Approximately 10% of patients treated with cilostazol experienced adverse side effects (palpitations, headache, diarrhea). Cilostazol was not found to have significant detrimental effects in hematologic or biochemical indices, including renal, hepatic, and blood coagulant function tests.

CONCLUSIONS

We found that 8 weeks of treatment with cilostazol 100 mg daily was safe and well tolerated for the treatment of type 2 diabetes with lower limb ischemic disease.

Protective effect of cilostazol against doxorubicin-induced cardiomyopathy in mice

Doxorubicin (Dox) is an effective anti-cancer drug, but its use is limited because of its adverse effect of inducing irreversible dilated cardiomyopathy. Cilostazol (Cilo), a potent phosphodiesterase III inhibitor, has been reported to have an anti-inflammatory effect. Here, we investigated whether Cilo has a protective effect against Dox-induced cardiomyopathy (DIC). Mice were randomly divided into four groups: saline control, Dox (15 mg/kg), Dox (15 mg/kg) plus Cilo (50mg/kg), and Cilo (50mg/kg). The results showed that the coadministration of Dox and Cilo significantly enhanced left-ventricular systolic function compared with Dox alone. In addition, Cilo treatment significantly reduced Dox-induced perivascular fibrosis, collagen concentration, and connective growth factor expression in the heart. Also, Cilo administration markedly reduced Dox-induced levels of serum B-type natriuretic peptide, dysferlin, high-mobility group protein B1, Toll-like receptor 4, nuclear factor-κB p65, and cyclooxygenase-2. Furthermore, Cilo treatment significantly reduced Dox-induced oxidative stress by lowering the translocation of Nrf2 into the nucleus and the expression of NQO1, heme oxygenase 1, and superoxide dismutase-1. Our results suggest that Cilo may be a potential antifibrotic, antioxidative, and anti-inflammatory drug for DIC.

Anti-inflammatory properties of resveratrol in the retinas of type 2 diabetic rats

Resveratrol (trans-3,5,4'-trihydroxystilbene) is a nutritional supplement with anti-inflammatory properties. The present study investigated the long-term anti-inflammatory property of resveratrol in the retinas of type 2 diabetic rats. Male Wistar rats were divided into four groups: normal control, diabetic control, resveratrol-treated normal rats and resveratrol-treated diabetic rats. Type 2 diabetes was induced by a single dose injection of streptozotocin (50 mg/kg; i.p.) 15 min after the administration of nicotinamide (110 mg/kg; i.p.) in 12-h fasted rats (the streptozotocin-nicotinamide type 2 diabetic model). Oral resveratrol administration (5 mg/kg per day for 4 months) significantly improved glucose tolerance, and alleviated hyperglycemia and weight loss in diabetic rats. Furthermore, resveratrol administration significantly decreased the elevated levels of nuclear factor-κB activity, and mRNA expression, tumour necrosis factor alpha level and apoptotic cells in the retinas of the diabetic rats. Furthermore, resveratrol did not significantly affect plasma insulin levels. Long-term resveratrol administration has beneficial anti-inflammatory properties in a rat model of diabetes. However, whether resveratrol exerts its effects directly or through reducing blood glucose levels requires further investigation.

Retinoic acid inhibits tissue factor and HMGB1 via modulation of AMPK activity in TNF-α activated endothelial cells and LPS-injected mice

OBJECTIVE

Retinoic acid (RA) is the active vitamin A derivative and has diverse immunomodulatory actions. We hypothesized that RA reduces prothrombotic mediators such as tissue factor (TF) in endothelial cells during inflammatory conditions via an AMPK-dependent pathway, which attenuates cardiovascular complications.

RESULTS

RA significantly increased AMPK and Akt phosphorylation in a time- and concentration-dependent manner in endothelial cells (EC). RA downregulated TF expression at the transcriptional and translational levels in TNF-α activated ECs, which was reversed by the silencing of AMPK and transfection of DN-AMPK. Interestingly, the PI3-kinase inhibitor LY294002 reversed the RA effect on TF expression. Increased AMPK phosphorylation by RA was inhibited by LY294002. However, increased Akt phosphorylation was not reduced by compound C, indicating that PI3K/Akt signaling modulates AMPK activity. In addition, RA reduced HMGB1 release in TNF-α activated ECs, which was reversed by both LY294001 and siAMPK. Importantly, administration of RA (1 mg/kg) significantly reduced blood TF activity, circulating HMGB1 and PAI-1 levels and expression of hepatic TF mRNA as well as fibrin deposition in LPS (5 mg/kg)-injected mice.

CONCLUSIONS

Taken together, the activation of PI3K/Akt by RA modulates AMPK activity in ECs and plays a crucial role in the inhibition of coagulatory factors such as TF, PAI-1, and HMGB1 in inflammatory conditions.

New therapeutic approaches for Alzheimer's disease and cerebral amyloid angiopathy

Accumulating evidence has shown a strong relationship between Alzheimer’s disease (AD), cerebral amyloid angiopathy (CAA), and cerebrovascular disease. Cognitive impairment in AD patients can result from cortical microinfarcts associated with CAA, as well as the synaptic and neuronal disturbances caused by cerebral accumulations of β-amyloid (Aβ) and tau proteins. The pathophysiology of AD may lead to a toxic chain of events consisting of Aβ overproduction, impaired Aβ clearance, and brain ischemia. Insufficient removal of Aβ leads to development of CAA and plays a crucial role in sporadic AD cases, implicating promotion of Aβ clearance as an important therapeutic strategy. Aβ is mainly eliminated by three mechanisms: (1) enzymatic/glial degradation, (2) transcytotic delivery, and (3) perivascular drainage (3-“d” mechanisms). Enzymatic degradation may be facilitated by activation of Aβ-degrading enzymes such as neprilysin, angiotensin-converting enzyme, and insulin-degrading enzyme. Transcytotic delivery can be promoted by inhibition of the receptor for advanced glycation end products (RAGE), which mediates transcytotic influx of circulating Aβ into brain. Successful use of the RAGE inhibitor TTP488 in Phase II testing has led to a Phase III clinical trial for AD patients. The perivascular drainage system seems to be driven by motive force generated by cerebral arterial pulsations, suggesting that vasoactive drugs can facilitate Aβ clearance. One of the drugs promoting this system is cilostazol, a selective inhibitor of type 3 phosphodiesterase. The clearance of fluorescent soluble Aβ tracers was significantly enhanced in cilostazol-treated CAA model mice. Given that the balance between Aβ synthesis and clearance determines brain Aβ accumulation, and that Aβ is cleared by several pathways stated above, multi-drugs combination therapy could provide a mainstream cure for sporadic AD.

Adaptive and regulatory mechanisms in aged rats with postoperative cognitive dysfunction

Inflammation may play a role in postoperative cognitive dysfunction. 5′ Adenosine monophosphate-activated protein kinase, nuclear factor-kappa B, interleukin-1β, and tumor necrosis factor-α are involved in inflammation. Therefore, these inflammatory mediators may be involved in postoperative cognitive dysfunction. Western immunoblot analysis revealed 5′ adenosine monophosphate-activated protein kinase and nuclear factor-kappa B in the hippocampus of aged rats were increased 1–7 days after splenectomy. Moreover, interleukin-1β and tumor necrosis factor-α were upregulated and gradually decreased. Therefore, these inflammatory mediators may participate in the splenectomy model of postoperative cognitive dysfunction in aged rats.

Cilostazol renoprotective effect: modulation of PPAR-γ, NGAL, KIM-1 and IL-18 underlies its novel effect in a model of ischemia-reperfusion

Cilostazol, a phosphodiesterase-III inhibitor, reportedly exhibits positive effects against ischemia/reperfusion (I/R)-induced injury in several models. However, its potential role against the renal I/R insult has not been elucidated. To test whether the PPAR-γ (of peroxisome proliferator activated receptor gamma) pathway is involved in the cilostazol effect, rats were randomized into sham, I/R, cilostazol (50 and 100 mg/kg per day, orally), pioglitazone (3 and 10 mg/kg per day, orally) and their combination at the low dose levels. Drugs regimens were administered for 14 days prior to the I/R induction. Pretreatment with cilostazol or pioglitazone provided significant protection against the I/R-induced renal injury as manifested by the attenuated serum levels of creatinine, blood urea nitrogen and cystatin C. Both drugs have also opposed the I/R-induced elevation in tissue contents/activity of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (Κim-1), nuclear factor-κB, interleuκin-18, caspase-1, as well as malondialdehyde, iNOS, myeloperoxidase, ICAM-1 and VCAM-1. Nevertheless, the drugs increased both the PPAR-γ transcriptional activity and the content of glutathione. Furthermore, combining the two low doses of both drugs produced effects comparable to that of the high dose level of either drug, advocating the fortification of pioglitazone renoprotective effect when given concomitantly with cilostazol. In conclusion, cilostazol purveyed conceivable novel renoprotective mechanisms and alleviated incidents associated with acute renal injury either alone or in combination with pioglitazone partially via the elevation of PPAR-γ besides the amendment of the aforementioned biomarkers.

Cilostazol effectively attenuates deterioration of albuminuria in patients with type 2 diabetes: a randomized, placebo-controlled trial

Cilostazol is an antiplatelet, antithrombotic agent with anti-inflammatory properties. To date, no clinical study has specifically evaluated the efficacy of cilostazol in patients with diabetic nephropathy (DN). We hypothesized that cilostazol might delay renal deterioration in DN patients at high risk of progression. Between April 2008 and April 2010, we screened 156 consecutive patients aged 35-80 years who were first diagnosed with type 2 diabetes after the age of 30 years. Of these, 90 patients with DN, as defined by morning spot urine microalbuminuria (MAU) >20 mg/L or an albumin-to-creatinine ratio (ACR) >30 μg/mg on at least two consecutive occasions within the prior 3 months, were enrolled into a 52-week randomized, single-blinded, placebo-controlled trial of oral cilostazol 100 mg twice daily or placebo (45 subjects in each group). Morning spot urine samples were collected to determine MAU and ACR. Fasting plasma levels of metabolic, endothelial variables, and inflammatory markers were examined. Following 52 weeks of treatment, urinary MAU and ACR were significantly reduced in the cilostazol group compared with the placebo group (P = 0.024 and P = 0.02, respectively). In regression analyses, changes in monocyte chemotactic protein-1, E-selectin, and soluble vascular cell adhesion molecule-1 (sVCAM-1) were significantly associated with changes in MAU and ACR. Net changes of E-selectin (P < 0.001) and sVCAM-1 (P < 0.05) were independent predictors of change in MAU and ACR, respectively. Our results suggest that cilostazol may effectively attenuate deterioration of albuminuria in patients with type 2 diabetes. This effect is likely mediated by an improvement of adhesion molecules.

Genistein suppresses LPS-induced inflammatory response through inhibiting NF-κB following AMP kinase activation in RAW 264.7 macrophages

Genistein, the major isoflavone in soybean, was recently reported to exert beneficial effects in metabolic disorders and inflammatory diseases. In the present study, we investigated the effects and mechanisms of a dietary concentration of genistein on the inflammatory response in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Our results demonstrated that genistein effectively inhibited the LPS-induced overproduction of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6), as well as LPS-induced nuclear factor kappa B (NF-κB) activation. In addition, the data also showed that genistein prevented LPS-induced decrease in adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. These effects were obviously attenuated by an AMPK inhibitor. Taken together, our results suggest that the dietary concentration of genistein is able to attenuate inflammatory responses via inhibition of NF-κB activation following AMPK stimulation. The data provide direct evidence for the potential application of low concentrations of genistein in the prevention and treatment of inflammatory diseases.

Ginkgo biloba extract (GbE) enhances the anti-atherogenic effect of cilostazol by inhibiting ROS generation

In this study, the synergistic effect of 6-[4-(1-cyclohexyl- 1H-tetrazol-5-yl) butoxy]-3,4-dihydro-2(1H )-quinolinone (cilostazol) and Ginkgo biloba extract (GbE) was examined in apolipoprotein E (ApoE) null mice. Co-treatment with GbE and cilostazol synergistically decreased reactive oxygen species (ROS) production in ApoE null mice fed a high-fat diet. Co-treatment resulted in a significantly decreased atherosclerotic lesion area compared to untreated ApoE mice. The inflammatory cytokines and adhesion molecules such as monocyte chemoattractant-1 (MCP-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and VCAM-1 which can initiate atherosclerosis were significantly reduced by the co-treatment of cilostazol with GbE. Further, the infiltration of macrophages into the intima was decreased by co-treatment. These results suggest that co-treatment of GbE with cilostazol has a more potent anti-atherosclerotic effect than treatment with cilostazol alone in hyperlipidemic ApoE null mice and could be a valuable therapeutic strategy for the treatment of atherosclerosis.

Cilostazol Decreases Ethanol-Mediated TNFalpha Expression in RAW264.7 Murine Macrophage and in Liver from Binge Drinking Mice

Alcoholic hepatitis is a leading cause of liver failure in which the increased production of tumor necrosis factor α (TNFα) plays a critical role in progression of alcoholic liver disease. In the present study, we investigated the effects of cilostazol, a selective inhibitor of type III phosphodiesterase on ethanol-mediated TNFα production in vitro and in vivo, and the effect of cilostazol was compared with that of pentoxifylline, which is currently used in clinical trial. RAW264.7 murine macrophages were pretreated with ethanol in the presence or absence of cilostazol then, stimulated with lipopolysacchride (LPS). Cilostazol significantly suppressed the level of LPS-stimulated TNFα mRNA and protein with a similar degree to that by pentoxifylline. Cilostazol increased the basal AMP-activated protein kinase (AMPK) activity as well as normalized the decreased AMPK by LPS. AICAR, an AMPK activator and db-cAMP also significantly decreased TNFα production in RAW264.7 cells, but cilostazol did not affect the levels of intracellular cAMP and reactive oxygen species (ROS) production. The in vivo effect of cilostazol was examined using ethanol binge drinking (6 g/kg) mice model. TNFα mRNA and protein decreased in liver from ethanol gavaged mice compared to that from control mice. Pretreatment of mice with cilostazol or pentoxifylline further reduced the TNFα production in liver. These results demonstrated that cilostazol effectively decrease the ethanol-mediated TNFα production both in murine macrophage and in liver from binge drinking mice and AMPK may be responsible for the inhibition of TNFα production by cilostazol.

Cilostazol suppression of arterial intimal hyperplasia is associated with decreased expression of sialyl Lewis X homing receptors on mononuclear cells and E-selectin in endothelial cells

BACKGROUND

An inflammatory reaction in vascular tissue is a potential factor linking restenosis after angioplasty. Although cilostazol, a selective phosphodiesterase type 3 inhibitor that is a unique antiplatelet drug and vasodilator, has been reported to be anti-inflammatory, its effect on the inflammatory action of mononuclear cells homing to endothelial cells is not clearly understood. In this study, whether cilostazol inhibits neointimal formation and improves inflammatory actions by inhibiting sialyl Lewis X (SLX) expression on mononuclear cells and E-selectin expression on endothelial cells was evaluated.

METHODS

The effect of cilostazol (1, 3, 10, 30 μM) on expression of E-selectin in human umbilical vein endothelial cells and SLX in rat mononuclear cells stimulated with lipopolysaccharide by immunofluorescence and real-time polymerase chain reaction (n = 3) was studied. Additionally, a double-balloon injury model was used on rat carotid arteries to evaluate vascular intimal hyperplasia. 0.1% cilostazol was administered 3 days before the first balloon injury, and the second balloon injury was performed 7 days after the first injury. Cilostazol administration was continued until rats were sacrificed 14 days after the second angioplasty. The expression of SLX on mononuclear cells and E-selectin on endothelial cells by immunofluorescence (n = 10) and real-time polymerase chain reaction (n = 5) were studied.

RESULTS

Cilostazol effectively inhibited the expression of SLX on mononuclear cells and E-selectin on endothelial cells. Cilostazol inhibited the migration of mononuclear cells in neointimal regions and neointimal hyperplasia after balloon injury. The numbers of macrophages and T-lymphocytes and the hyperplasia area in neointimal regions decreased from 71.06 ± 20.04, 1121 ± 244.4 cells per section, 206,400 ± 96,150 mm(2) to 29.65 ± 16.73, 374.2 ± 124.5 cells per section, and 101,900 ± 16,150 mm(2) due to the administration of cilostazol.

CONCLUSIONS

These results demonstrate that the protective effect of cilostazol against neointimal hyperplasia may be mediated by its anti-inflammatory actions of mononuclear cells homing to endothelial cells by decreasing SLX and E-selectin expression.

CLINICAL RELEVANCE

It is reported that cilostazol inhibits neointimal hyperplasia by decreasing the expression of some cell-adhesion molecules. We evaluated the effects of cilostazol for the expression of sialyl Lewis X (SLX) on mononuclear cells and E-selectin on endothelial cells, which interaction is the first step of inflammation action. Cilostazol was thought to show the anti-inflammatory actions by decreasing SLX and E-selectin expression in addition to decreasing the expression of some cell-adhesion molecules.

Successful shortening of tuberculosis treatment using adjuvant host-directed therapy with FDA-approved phosphodiesterase inhibitors in the mouse model

Global control of tuberculosis (TB), an infectious disease that claims nearly 2 million lives annually, is hindered by the long duration of chemotherapy required for curative treatment. Lack of adherence to this intense treatment regimen leads to poor patient outcomes, development of new or additional drug resistance, and continued spread of M.tb. within communities. Hence, shortening the duration of TB therapy could increase drug adherence and cure in TB patients. Here, we report that addition of the United Stated Food and Drug Administration-approved phosphodiesterase inhibitors (PDE-Is) cilostazol and sildenafil to the standard TB treatment regimen reduces tissue pathology, leads to faster bacterial clearance and shortens the time to lung sterilization by one month, compared to standard treatment alone, in a murine model of TB. Our data suggest that these PDE-Is could be repurposed for use as adjunctive drugs to shorten TB treatment in humans.

Cilostazol inhibits matrix invasion and modulates the gene expressions of MMP-9 and TIMP-1 in PMA-differentiated THP-1 cells

The invasion of monocytes into the subendothelium space plays an important role in the early stage of atherosclerosis. Cilostazol, a specific phosphodiesterase type III (PDE3) inhibitor, has been shown to exhibit anti-atherosclerotic effect. The present study aimed to investigate the modulating effects of cilostazol on monocyte invasion and the gene expressions of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. We found that PMA significantly increased the invasive ability and the MMP-9 activity of THP-1 cells, as analyzed by matrix invasion assay and gelatin zymography, respectively. The increased expression of MMP-9 was demonstrated at both the RNA and protein levels by RT/real-time PCR and western blot analysis. These changes were markedly inhibited by cilostazol in a dose-dependent manner, which also could be observed when cAMP analog was used. On the contrary, the expression of TIMP-1, an inhibitor of MMP-9, was significantly upregulated by cilostazol dose dependently at both the RNA and protein levels. Reverse zymography further confirmed the increase of TIMP-1 activity after cilostazol treatment. The increase of TIMP-1 by cilostazol, however, was not cAMP-dependent. Cilostazol reduced the MMP-9 promoter activity and suppressed the nuclear translocation of NF-κB, indicating that the inhibitory effect of cilostazol is at the transcriptional level. In conclusion, the present study provides an additional mechanism underlying the anti-atherosclerotic effect of cilostazol by inhibiting the monocyte invasion and modulating the gene expressions of MMP-9 and TIMP-1 in monocytes upon differentiating to macrophages.

Platelet inhibition by adjunctive cilostazol versus high maintenance-dose clopidogrel in patients with acute myocardial infarction according to cytochrome P450 2C19 genotype

OBJECTIVES

The aim of this study was to assess the degree of platelet inhibition by adjunctive cilostazol in patients with acute myocardial infarction (AMI) according to hepatic cytochrome P450 2C19 (CYP2C19) genotype.

BACKGROUND

Although adjunctive cilostazol intensifies platelet inhibition in AMI patients, it is not established whether this regimen can be free from the effect of CYP2C19 loss-of-function variants (*2/*3).

METHODS

We randomly assigned 126 AMI patients with available CYP2C19 genotyping to receive adjunctive cilostazol (triple group; n = 64) or high maintenance-dose (MD) clopidogrel of 150 mg/day (high-MD group; n = 62). Using conventional aggregometry and VerifyNow (Accumetrics Inc., San Diego, California), platelet reactivity was measured at pre-discharge and 30-day follow-up. Primary endpoint was change in maximal platelet aggregation (ΔAgg(max)) between pre-discharge and 30-day follow-up. High on-treatment platelet reactivity (HPR) was defined as 20 μmol/l adenosine diphosphate-induced maximal platelet aggregation (Agg(max)) >59%.

RESULTS

In noncarriers, despite numerically greater inhibition by adjunctive cilostazol, changes in platelet measures and the rate of HPR did not significantly differ between the 2 groups. In carriers, ΔAgg(max) after 5 and 20 μmol/l adenosine diphosphate stimuli was significantly higher in the triple (n = 39) versus high-MD group (n = 38) (21.8 ± 13.9% vs. 9.0 ± 13.3%, p < 0.001, and 24.2 ± 17.2% vs. 7.7 ± 15.5%, p < 0.001, respectively). Likewise, changes in late platelet aggregation and P2Y12 reaction unit were consistently greater in the triple versus high-MD group. Fewer patients in the triple group met the criteria of HPR at 30-day follow-up than in the high-MD group (15.4% vs. 44.7%, p = 0.005).

CONCLUSIONS

Compared with high-MD clopidogrel, adjunctive cilostazol significantly enhances platelet inhibition and reduces the rate of HPR, especially in AMI patients with CYP2C19 loss-of-function variants. (Adjunctive Cilostazol Versus High Maintenance-Dose Clopidogrel in Acute Myocardial Infarction (AMI) Patients According to CYP2C19 Polymorphism [ACCELAMI2C19]; NCT00915733).

AMP-activated protein kinase inhibits homocysteine-induced dysfunction and apoptosis in endothelial progenitor cells

PURPOSE

Homocysteine (Hcy) has been shown to induce oxidative stress and apoptosis of endothelial progenitor cells (EPCs). AMP-activated protein kinase (AMPK) has been reported to have protective effects on endothelial function. However, effects of AMPK activation on Hcy-induced EPCs injury remain to be determined. In this study, we examined the effect of AMPK phosphorylation on Hcy-induced NO bioavailability impairment and NADPH oxidase 4 (Nox4) derived reactive oxygen species (ROS) accumulation in EPCs.

MATERIALS AND METHODS

EPCs were pre-treated with various concentrations of 5-amino-4-imidazolecarboxamide riboside-l-beta-D-ribofuranoside (AICAR), a pharmacological agonist of AMPK, and then incubated with Hcy for 24 h. Furthermore, we challenged EPCs with Hcy in the presence or absence of atorvastatin and AMPK-DN which expressed a dominant-negative mutant of AMPK. Migration, proliferation and apoptosis were assayed to evaluate EPCs function. NO production, expression of endothelial nitric oxide synthase (eNOS), intracellular ROS levels and Nox4 activation were determined to explore the potential mechanisms of Hcy-induced EPCs dysfunction.

RESULTS

We observed that AICAR attenuated the inhibition effects of Hcy on EPCs migration and proliferation. The apoptosis rates of EPCs were down-regulated by AICAR compared with the group treated with Hcy only [(0.25 mmol/L AICAR: 10.48 ± 1.6%; 0.5 mmol/L AICAR: 8.70 ± 1.0%; 1 mmol/L AICAR: 5.83 ± 1.3%) vs. (500 μmol/L Hcy only: 12.60 ± 1.9%)]. We also found that NO production and eNOS expression were up-regulated by AICAR compared with the group treated with Hcy only, while ROS accumulation and Nox4 activation were inhibited. Furthermore, atorvastatin suppressed Hcy-induced dysfunction of EPCs, increased NO production and eNOS expression, and down-regulated ROS accumulation and Nox4 activation. And these effects of atorvastatin could be blunted by AMPK-DN.

CONCLUSION

AMPK activation inhibits eNOS down-regulation and Nox4-derived ROS accumulation induced by Hcy in EPCs, and may contribute to the protective effects of atorvastatin on endothelial function.

Cilostazol reduces MCP-1-induced chemotaxis and adhesion of THP-1 monocytes by inhibiting CCR2 gene expression

The chemotaxis and adhesion of monocytes to the injured endothelium in the early atherosclerosis is important. Cilostazol, a specific phosphodiesterase type III inhibitor, is known to exhibit anti-atherosclerotic effects mediated by different mechanisms. This study aimed to investigate the modulating effect of cilostazol on the MCP-1-induced chemotaxis and adhesion of monocytes. The gene expression of CCR2, the major receptor of MCP-1 in THP-1 monocytes, was also analyzed. The chemotaxis of monocytes toward MCP-1 was investigated using the transwell filter assay. Cilostazol dose-dependently inhibited the MCP-1-induced chemotaxis of monocytes which was shown to be cAMP-dependent. Using western blot analysis and flow cytometry method, we demonstrated the decrease of CCR2 protein at the cell membrane of monocytes by cilostazol treatment. Results from RT/real-time PCR confirmed the decrease of CCR2 mRNA expression by cilostazol which was also mediated by cAMP. Similar inhibition was also noted in human peripheral monocytes. The post-CCR2 signaling pathways including p44/42 and p38 MAPK were examined by western blot analysis. Result confirmed the inhibitory effect of cilostazol on the phosphorylation of p44/42 and p38 MAPK after MCP-1 stimulation. The activation of monocytes after MCP-1 treatment exhibited enhanced adhesion to vascular endothelial cells which was dose-dependently suppressed by cilostazol. Together, cilostazol was demonstrated, for the first time, to inhibit the CCR2 gene expression and MCP-1-induced chemotaxis and adhesion of monocytes which might therefore reduce the infiltration of monocytes during the early atherosclerosis. The present study provides an additional molecular mechanism underlying the anti-atherosclerotic effects of cilostazol.

Nitric oxide-induced activation of the AMP-activated protein kinase α2 subunit attenuates IκB kinase activity and inflammatory responses in endothelial cells

Background

In endothelial cells, activation of the AMP-activated protein kinase (AMPK) has been linked with anti-inflammatory actions but the events downstream of kinase activation are not well understood. Here, we addressed the effects of AMPK activation/deletion on the activation of NFκB and determined whether the AMPK could contribute to the anti-inflammatory actions of nitric oxide (NO).

Methodology/Principal Findings

Overexpression of a dominant negative AMPKα2 mutant in tumor necrosis factor-α-stimulated human endothelial cells resulted in increased NFκB activity, E-selectin expression and monocyte adhesion. In endothelial cells from AMPKα2^-/- mice the interleukin (IL)-1β induced expression of E-selectin was significantly increased. DETA-NO activated the AMPK and attenuated NFκB activation/E-selectin expression, effects not observed in human endothelial cells in the presence of the dominant negative AMPK, or in endothelial cells from AMPKα2^-/- mice. Mechanistically, overexpression of constitutively active AMPK decreased the phosphorylation of IκB and p65, indicating a link between AMPK and the IκB kinase (IKK). Indeed, IKK (more specifically residues Ser177 and Ser181) was found to be a direct substrate of AMPKα2 in vitro. The hyper-phosphorylation of the IKK, which is known to result in its inhibition, was also apparent in endothelial cells from AMPKα2^+/+ versus AMPKα2^-/- mice.

Conclusions

These results demonstrate that the IKK is a direct substrate of AMPKα2 and that its phosphorylation on Ser177 and Ser181 results in the inhibition of the kinase and decreased NFκB activation. Moreover, as NO potently activates AMPK in endothelial cells, a portion of the anti-inflammatory effects of NO are mediated by AMPK.

Cilostazol inhibits cytokine-induced tetrahydrobiopterin biosynthesis in human umbilical vein endothelial cells

AIMS

Cilostazol, a type III phosphodiesterase inhibitor, is utilized for the treatment of intermittent claudication and is considered to have the beneficial effects against the atherogenic process. In the present study, we examined the effects of cilostazol on BH(4) biosynthesis in HUVEC treated with a mixture of the pro-inflammatory cytokines IFN-γ and TNF-α.

METHODS

Isolated HUVECs were grown to confluence and treated with IFN-γ (300 units/mL) and TNF-α (300 units/mL) for 16 h in order to stimulate BH(4) biosynthesis. The BH(4) levels were measured by HPLC. The mRNA expression of GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme of BH(4) biosynthesis, and GTPCH feedback regulatory protein (GFRP) were quantified by real-time PCR. The GTPCH protein expression was assessed by western blot analysis.

RESULTS

Cilostazol significantly reduced the BH(4) levels in cytokine-stimulated HUVEC. Cilostazol produced a concomitant increase in the cAMP levels in HUVEC. Cilostazol decreased the GTPCH activity as well as the expression of GTPCH mRNA and protein. 8-bromo-cAMP (8Br-cAMP), a cell-permeable cAMP analogue, did not reproduce the effects of cilostazol. Cilostazol did not affect the cytokine-induced inhibition of GFRP mRNA expression.

CONCLUSIONS

We conclude that cilostazol inhibited cytokine-stimulated BH(4) biosynthesis via a cAMP-independent mechanism in HUVEC. Our data indicate that cilostazol reduced GTPCH activity and did so by suppressing the GTPCH protein levels.

Cytochrome 2C19 polymorphism and response to adjunctive cilostazol versus high maintenance-dose clopidogrel in patients undergoing percutaneous coronary intervention

BACKGROUND

Among patients treated with clopidogrel, carriers of the cytochrome P450 (CYP) 2C19 loss-of-function allele have shown increased platelet reactivity and higher rates of ischemic events. Although adjunctive cilostazol to dual antiplatelet therapy (or "triple antiplatelet therapy") intensifies platelet inhibition, it remains unknown whether triple antiplatelet therapy after percutaneous coronary intervention can achieve adequate platelet inhibition in patients with the CYP2C19 mutant allele.

METHODS AND RESULTS

CYP2C19 genotyping for *1, *2, and *3 was performed in 134 high-risk patients undergoing elective percutaneous coronary intervention. After measurement of preprocedural platelet reactivity, patients were randomly assigned to receive either adjunctive cilostazol 100 mg twice daily (triple group; n=69) or high maintenance-dose (MD) clopidogrel of 150 mg daily (high-MD group; n=65). Using light transmittance aggregometry and the VerifyNow P2Y(12) assay, platelet reactivity was assessed before the index procedure and at 30-day follow-up. The primary end point was absolute change in maximal platelet aggregation (ΔAgg(max)) according to CYP2C19 genotyping. High posttreatment platelet reactivity was defined as 5 μmol/L ADP-induced maximal platelet aggregation >50%. In noncarriers of the CYP2C19*2/*3 mutant allele, ΔAgg(max) values after 5 and 20 μmol/L ADP stimuli did not differ significantly between the triple (n=22) versus the high-MD group (n=22) (23.6±21.6% versus 16.6±15.4%, P=0.224 and 26.4±22.2% versus 18.6±14.9%, P=0.174, respectively). Absolute changes in late platelet aggregation and P2Y(12) reaction unit were not different between the groups. The rate of high posttreatment platelet reactivity at 30-day follow-up also was comparable between the triple versus the high-MD group (4.5% versus 13.6%, P=0.607). In carriers of at least 1 CYP2C19*2/*3 mutant allele, the triple group (n=47) showed greater values of ΔAgg(max) after addition of 5 μmol/L (25.8±16.8% versus 11.1±19.8%, P<0.001) and 20 μmol/L ADP (26.3±16.0% versus 11.5±16.3%, P<0.001) compared with the high-MD group (n=43). Likewise, absolute changes in late platelet aggregation and P2Y(12) reaction unit were consistently greater in the triple versus the high-MD group. Fewer patients in the triple group met the criteria of high posttreatment platelet reactivity at 30-day follow-up compared with the high-MD group (6.4% versus 37.2%, P<0.001).

CONCLUSIONS

Among high-risk patients undergoing elective percutaneous coronary intervention, adjunctive cilostazol can achieve consistently intensified platelet inhibition and reduce the risk of high posttreatment platelet reactivity irrespective of CYP2C19 genotyping.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01012193.

5-aminoimidazole-4-carboxamide ribonucleoside and AMP-activated protein kinase inhibit signalling through NF-κB

Activation of nuclear factor-kappa B (NF-κB) is one of the most important pro-inflammatory mechanisms in disease. In this study, we show that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an intermediate in nucleoside metabolism, inhibits signalling by NF-κB in three cell types, including bovine aortic endothelial cells (BAEC). The block in the NF-κB signalling pathway occurred beyond degradation of IκB-α and movement of p65 into the nucleus of BAEC. There was, however, reduced binding of NF-κB from AICAR-treated cells to a κB-consensus oligonucleotide, suggesting that part of the mechanism was a reduction in NF-κB DNA-binding activity. Although AICAR is metabolized to ZMP and then adenosine, adenosine had no effect on activation of an NF-κB reporter. ZMP, however, activates the metabolic stress-sensing AMP-activated protein kinase (AMPK). Transfection of active AMPK into BAEC reduced NF-κB reporter activity compared with a kinase-dead mutant, suggesting that part of the ability of AICAR to inhibit NF-κB signalling is due to activation of AMPK. Inhibition of NF-κB signalling may be important in the anti-inflammatory action of drugs such as sulfasalazine and methotrexate, which led to the accumulation of AICAR within target cells.

Lipid-induced insulin resistance is prevented in lean and obese myotubes by AICAR treatment

The molecular mechanisms of obesity-associated insulin resistance are becoming increasingly clear, and the effects of various lipid molecules, such as diacylglycerol and ceramide, on the insulin signal are being actively explored. To better understand the divergent response to lipid exposure between lean and obese, we incubated primary human muscle cells from lean [body mass index (BMI) <25 kg/m(2)] and morbidly obese (BMI >40 kg/m(2)) subjects with the saturated fatty acid palmitate. Additionally, given that AMPK-activating drugs are widely prescribed for their insulin-sensitizing effects, we sought to determine whether 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR)-stimulated AMPK activation could prevent or reverse the deleterious effects of lipid on insulin signaling. We found that a 1-h palmitate incubation in lean myotubes reduced (P < 0.05) insulin-stimulated phosphoprotein kinase B (Akt), Akt substrate 160 (AS160), and inhibitory factor kappaBalpha (IkappaBalpha) mass, all of which were prevented with AICAR inclusion. With a longer incubation, we observed that myotubes from morbidly obese individuals appear to be largely resistant to the detrimental effects of 16 h lipid exposure as was evident, in contrast to the lean, by the absence of a reduction in insulin-stimulated insulin receptor substrate (IRS)-1 Tyr phosphorylation, phospho-Akt, and phospho-AS160 (P < 0.05). Furthermore, 16 h lipid exposure significantly reduced IkappaBalpha levels and increased phosphorylation of c-Jun NH(2)-terminal kinase (JNK) and IRS1-Ser(312) in lean myotubes only (P < 0.05). Despite a divergent response to lipid between lean and obese myotubes, AICAR inclusion improved insulin signaling in all myotubes. These findings suggest an important role for regular exercise in addition to offering a potential mechanism of action for oral AMPK-activating agents, such as thiazolidinediones and metformin.

Abscisic acid ameliorates experimental IBD by downregulating cellular adhesion molecule expression and suppressing immune cell infiltration

BACKGROUND & AIMS

Abscisic acid (ABA) has shown effectiveness in ameliorating inflammation in obesity, diabetes and cardiovascular disease models. The objective of this study was to determine whether ABA prevents or ameliorates experimental inflammatory bowel disease (IBD).

METHODS

C57BL/6J mice were fed diets with or without ABA (100mg/kg) for 35 days prior to challenge with 2.5% dextran sodium sulfate (DSS). The severity of clinical disease was assessed daily. Colonic mucosal lesions were evaluated by histopathology, and cellular adhesion molecular and inflammatory markers were assayed by real-time quantitative PCR. Flow cytometry was used to quantify leukocyte populations in the blood, spleen, and mesenteric lymph nodes (MLN). The effect of ABA on cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression in splenocytes was also investigated.

RESULTS

ABA significantly ameliorated disease activity, colitis and reduced colonic leukocyte infiltration and inflammation. These improvements were associated with downregulation in vascular cell adhesion marker-1 (VCAM-1), E-selectin, and mucosal addressin adhesion marker-1 (MAdCAM-1) expression. ABA also increased CD4(+) and CD8(+) T-lymphocytes in blood and MLN and regulatory T cells in blood. In vitro, ABA increased CTLA-4 expression through a PPAR γ-dependent mechanism.

CONCLUSIONS

We conclude that ABA ameliorates gut inflammation by modulating T cell distribution and adhesion molecule expression.

Anti-inflammatory role of cilostazol in vascular smooth muscle cells in vitro and in vivo

AIM

Cilostazol is a selective inhibitor of phosphodiesterase 3, by which it increases intracellular cAMP and activates protein kinase A, thereby inhibiting platelet aggregation and inducing peripheral vasodilation. We investigated whether cilostazol might prevent nuclear factor (NF)-kappaB activation by activating AMP-activated protein kinase (AMPK) in vascular smooth muscle cells (VSMC).

METHODS AND RESULTS

Cilostazol was observed to activate AMPK, as well as its downstream target, acetyl-CoA carboxylase, in rat VSMC. Phosphorylation of AMPK with cilostazol was not affected by co-treatment with an adenylate cyclase inhibitor, SQ 22536. Furthermore, a cell-permeable cyclic AMP analog, pCTP-cAMP, did not influence cilostazol-induced AMPK phosphorylation. These findings suggest that cilostazol-induced AMPK activation occurs through a signalling pathway independent of cyclic AMP. Cilostazol dose-dependently inhibited LPS-induced NF-kappaB activation in the present study. It was also observed to inhibit LPS-induced iNOS gene promoter activity and iNOS gene expression, resulting in markedly reduced NO production. An AMPK inhibitor compound C or siRNA for AMPK attenuated the observed cilostazol-induced inhibition of NF-kappaB activation by LPS. Ingestion of cilostazol inhibited NF-kappaB activation, as well as the induction of iNOS mRNA and protein expression, within the aortas of LPS-treated rats.

CONCLUSION

In light of these findings, we suggest that cilostazol might attenuate cytokine-induced expression of the iNOS gene by inhibiting NF-kappaB following AMPK activation in VSMC.

Activation and signaling by the AMP-activated protein kinase in endothelial cells

The AMP-activated protein kinase (AMPK) was initially identified as the kinase that phosphorylates the 3-hydroxy 3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme for cholesterol biosynthesis. As the name suggests, the AMPK is activated by increased intracellular concentrations of AMP, and is generally described as a "metabolite-sensing kinase" and when activated initiates steps to conserve cellular energy. Although there is a strong link between the activity of the AMPK and metabolic control in muscle cells, the activity of the AMPK in endothelial cells can be regulated by stimuli that affect cellular ATP levels, such as hypoxia as well as by fluid shear stress, Ca(2+)-elevating agonists, and hormones such as adiponectin. To date the AMPK in endothelial cells has been implicated in the regulation of fatty acid oxidation, small G protein activity and nitric oxide production as well as inflammation and angiogenesis. Moreover, there is evidence indicating that the activation of the AMPK may help to prevent the vascular complications associated with the metabolic syndrome.