Adjustment for Renal Function Improves the Prognostic Performance of Urinary Thromboxane Metabolites

BACKGROUND

Systemic thromboxane A2 generation, assessed by quantifying the concentration of stable thromboxane B2 metabolites (TXB2-M) in the urine adjusted for urinary creatinine, is strongly associated with mortality risk. We sought to define optimal TXB2-M cutpoints for aspirin users and nonusers and determine if adjusting TXB2-M for estimated glomerular filtration rate (eGFR) in addition to urinary creatinine improved mortality risk assessment.

METHODS

Urinary TXB2-M were measured by competitive ELISA in 1363 aspirin users and 1681 nonusers participating in the Framingham Heart Study. Cutpoints were determined for TXB2-M and TXB2-M/eGFR using log-rank statistics and used to assess mortality risk by Cox proportional hazard modeling and restricted mean survival time. Multivariable models were compared using the Akaike Information Criterion (AIC). A cohort of 105 aspirin users with heart failure was used for external validation.

RESULTS

Optimized cutpoints of TXB2-M were 1291 and 5609 pg/mg creatinine and of TXB2-M/eGFR were 16.6 and 62.1 filtered prostanoid units (defined as pg·min/creatinine·mL·1.73 m2), for aspirin users and nonusers, respectively. TXB2-M/eGFR cutpoints provided more robust all-cause mortality risk discrimination than TXB2-M cutpoints, with a larger unadjusted hazard ratio (2.88 vs 2.16, AIC P < 0.0001) and greater differences in restricted mean survival time between exposure groups (1.46 vs 1.10 years), findings that were confirmed in the external validation cohort of aspirin users. TXB2-M/eGFR cutpoints also provided better cardiovascular/stroke mortality risk discrimination than TXB2-M cutpoints (unadjusted hazard ratio 3.31 vs 2.13, AIC P < 0.0001).

CONCLUSION

Adjustment for eGFR strengthens the association of urinary TXB2-M with long-term mortality risk irrespective of aspirin use.

Establishment of 11-dehydro-thromboxane B2 time-resolved immunoassay and application in membranous nephropathy

BACKGROUND

11-Dehydro-thromboxane B2 (11-dehydro-TXB2) is the final stable metabolite of thromboxane A2 (TXA2) and is involved in thrombus formation. Patients with membranous nephropathy (MN) are prone to thromboembolism events.

METHODS

Time-resolved fluorescence immunoassay (TRFIA) for 11-dehydro-TXB2 was established by indirect competitive method. The coated 11-dehydro-TXB2-BSA conjugate was used to bind the 11-dehydro-TXB2 antibody competitively to the 11-dehydro-TXB2 antigen in the samples, followed by Eu3+-labeled goat anti-mouse IgG antibody, to detect 11-dehydro-TXB2. This study measured 11-dehydro-TXB2 concentrations in serum samples from healthy individuals and patients with MN.

RESULTS

The linear range of TRFIA was 16.38-2000 pg/mL, the sensitivity was 4.70 pg/mL, the average coefficients of variation from intra-assay and inter-assay were 3.50% and 4.95%, respectively, and the recovery was 99.38%. The serum level of 11-dehydro-TXB2 in patients with MN was significantly higher than that in healthy subjects (P < 0.05). The serum 11-dehydro-TXB2 concentration detected by TRFIA was highly consistent with that by ELISA (ρ = 0.900).

DISCUSSION

This study successfully established a new highly sensitive method for the detection of 11-dehydro-TXB2 in serum. 11-Dehydro-TXB2 has great potential in evaluating the risk of thromboembolic events in patients with MN and is expected to be applied to other thromboembolic-related diseases.

The Trace Element Selenium Is Important for Redox Signaling in Phorbol Ester-Differentiated THP-1 Macrophages

Physiological selenium (Se) levels counteract excessive inflammation, with selenoproteins shaping the immunoregulatory cytokine and lipid mediator profile. How exactly differentiation of monocytes into macrophages influences the expression of the selenoproteome in concert with the Se supply remains obscure. THP-1 monocytes were differentiated with phorbol 12-myristate 13-acetate (PMA) into macrophages and (i) the expression of selenoproteins, (ii) differentiation markers, (iii) the activity of NF-κB and NRF2, as well as (iv) lipid mediator profiles were analyzed. Se and differentiation affected the expression of selenoproteins in a heterogeneous manner. GPX4 expression was substantially decreased during differentiation, whereas GPX1 was not affected. Moreover, Se increased the expression of selenoproteins H and F, which was further enhanced by differentiation for selenoprotein F and diminished for selenoprotein H. Notably, LPS-induced expression of NF-κB target genes was facilitated by Se, as was the release of COX- and LOX-derived lipid mediators and substrates required for lipid mediator biosynthesis. This included TXB₂, TXB₃, 15-HETE, and 12-HEPE, as well as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Our results indicate that Se enables macrophages to accurately adjust redox-dependent signaling and thereby modulate downstream lipid mediator profiles.

Extract of Danggui-Shaoyao-San ameliorates cognition deficits by regulating DHA metabolism in APP/PS1 mice

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine formula Danggui-Shaoyao-San (DSS) has been reported to show therapeutic effect on alleviating the symptoms of Alzheimer's disease (AD).

AIM OF THE STUDY

The present study aims to investigate the relation between DSS treatment of AD and DHA metabolism and evaluates its neuroprotective effect on cognitive in APP/PS1 mice.

MATERIAL AND METHODS

DSS (1.6, 3.2, 6.4 g/kg/day) or Aricept (3 mg/kg/day) was orally administered (i.g.) to APP/PS1 mice, and saline was orally administered to Wild-type (WT) male mice as control group. Then, the Morris water maze (MWM) test, Y-maze spontaneous alternation test, open filed test and fear conditioning test were conducted for evaluation of learning and memory abilities. The DHA content was assessed by HPLC-MS/MS. Physiological indices were determined, including triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), ROS level, activity of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), PEG2, TXB2 and LTB4. The expressions of COX-1, COX-2, cPLA2, iPLA2, 15-LOX, and were assessed by Western blot.

RESULTS

APP/PS1 mice showed serious cognitive impairment in behavioral tests. However, treatment of DSS extract significantly ameliorated the cognitive deficits of APP/PS1 mice. Biochemical measurements showed the increases in TG, TC, LDL-c and the decrease in HDL-c in APP/PS1 mice compared with WT mice, and DSS extract significantly retarded these changes. Low content of DHA, low expression of iPLA2 and 15-LOX were observed both in hippocampus and cortex of APP/PS1 mice, while DSS extract significantly restored these changes. Additionally, the abnormal activity of SOD and ROS level, the decreased levels of MDA and GSH were observed in APP/PS1 mice, while DSS extract prominently lessened these changes. Moreover, DSS extract decreased the level of PEG2, TXB2 and LTB4 and also attenuated the expression of cPLA2, COX-1 and COX-2 in hippocampus as well as cortex of APP/PS1 mice.

CONCLUSIONS

Based on these results, we suggest that DSS play a positive effective role in increasing DHA content by up-regulating iPLA2 and 15-LOX, resulting in ameliorating oxidative stress and inflammation and finally ameliorating cognition deficits in APP/PS1 mice.

The Biology of Prostaglandins and Their Role as a Target for Allergic Airway Disease Therapy

Prostaglandins (PGs) are a family of lipid compounds that are derived from arachidonic acid via the cyclooxygenase pathway, and consist of PGD₂, PGI₂, PGE₂, PGF₂, and thromboxane B₂. PGs signal through G-protein coupled receptors, and individual PGs affect allergic inflammation through different mechanisms according to the receptors with which they are associated. In this review article, we have focused on the metabolism of the cyclooxygenase pathway, and the distinct biological effect of each PG type on various cell types involved in allergic airway diseases, including asthma, allergic rhinitis, nasal polyposis, and aspirin-exacerbated respiratory disease.

Hemostatic effect of acylated ghrelin in control and sleeve gastrectomy-induced rats: mechanisms of action

This study investigated the effect of acylated ghrelin (AG) deficiency after sleeve gastrectomy (SG) or chronic administration in control and SG-indiuced rats on platelet function, coagulation, and fibrinolysis. Administration of AG (100 µg/kg, subcutaneously) to control or SG rats significantly inhibited platelets aggregation and lowered levels of Von-Willebrand factor (vWF), fibrinogen, and thromboxane B2. Concomitantly, it decreased circulatory levels and aortic expression levels of plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) and increased the aortic expression of the endothelial nitric oxidase (eNOS). However, AG inhibited angiotensin-II (ANGII)-induced upregulation of tissue factor pathway inhibitor (TPAI) and TF and increased activity of TF and increases eNOS expression in cultured endothelial cells, an effect that was abolished by the addition of D-[lys3]-GHRP-6, a selective AG receptor (GHSR-1a) blocker or L-Name, a potent eNOS inhibitor. In conclusion, AG has an anti-platelet, anti-coagulant, and fibrinolytic roles mediated through GHSR-1a to enhance nitric oxide synthesis.

Effects of functionalized silver nanoparticles on aggregation of human blood platelets

PURPOSE

We studied the effects of silver nanoparticles (AgNPs) on human blood platelet function. We hypothesized that AgNPs, a known antimicrobial agent, can be used as blood-compatible, "ideal material'' in medical devices or as a drug delivery system. Therefore, the aim of the current study was to investigate if functionalized AgNPs affect platelet function and platelets as well as endothelial cell viability in vitro.

METHODS

AgNPs, functionalized with reduced glutathione (GSH), polyethylene glycol (PEG) and lipoic acid (LA) were synthesized. Quartz crystal microbalance with dissipation was used to measure the effect of AgNPs on platelet aggregation. Platelet aggregation was measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast microscopy. Flow cytometry was used to detect surface abundance of platelet receptors. Lactate dehydrogenase test was used to assess the potential cytotoxicity of AgNPs on human blood platelets, endothelial cells, and fibroblasts. Commercially available ELISA tests were used to measure the levels of thromboxane B2 and metalloproteinases (MMP-1, MMP-2) released by platelets as markers of platelet activation.

RESULTS

2 nm AgNPs-GSH, 3.7 nm AgNPs-PEG both at 50 and 100 µg/mL, and 2.5 nm AgNPs-LA at 100 µg/mL reduced platelet aggregation, inhibited collagen-mediated increase in total P-selectin and GPIIb/IIIa, TXB2 formation, MMP-1, and MMP-2 release. The tested AgNPs concentrations were not cytotoxic as they did not affect, platelet, endothelial cell, or fibroblast viability.

CONCLUSION

All tested functionalized AgNPs inhibited platelet aggregation at nontoxic concentrations. Therefore, functionalized AgNPs can be used as an antiplatelet agent or in design and manufacturing of blood-facing medical devices, such as vascular grafts, stents, heart valves, and catheters.

[PYRIDOXAL-5-PHOSPHATE RESTORES HYDROGEN SULFIDE SYNTHES AND REDOX STATE OF HEART AND BLOOD VESSELS TISSUE IN OLD ANIMALS]

It was shown the alterations in hydrogen sulfide (H(2)S) metabolism and the development of oxidative and nitrozative stress in cardiovascular system by aging. The administration of pyridoxal-5-phosphate as cofactor of H(2)S synthesizing enzymes restored endogenous H(2)S level and redox state in the heart and aorta tissues. Under these conditions, the following indicators of oxidative stress were significantly decreased in heart and aorta tissues: superoxide generation rate (·0(2)(-)) and hydroxyl (·OH) anion radicals, compared with significantly elevated levels of these parameters in old animals. We also found the reduction of non-enzymatic (diene conjugates and malonic dialdehyde) and enzymatic (uric acid, LTC(4) and TxB(2)) lipid oxidation products levels in old rats under H(2)S synthesis stimulation that confirms the restriction of oxidative stress. An important consequence of endogenous synthesis stimulation of hydrogen sulfide during aging is a decrease of nitrozative stress, such as iNOS activity and nitrate reductase, as well as recovery of constitutive NO synthase activity, indicating the importance of this gas transmitter in cardiovascular system. Thus, stimulation of hydrogen sulfide endogenous synthesis contributed to reduced production of reactive oxygen species (oxidative stress) and nitrogen (nitrozative stress) in heart and aorta tissues with aging. The presence of a pronounced antioxidant effect and modulating influence of pyridoxal-5- phosphate in the redox state of heart tissue and blood vessels during aging suggests cardioprotective properties of the substance and prospects for future research.

ApoL1 renal risk variants induce aberrant THP-1 monocyte differentiation and increase eicosanoid production via enhanced expression of cyclooxygenase-2

Apolipoprotein L1 ( ApoL1) genetic variants are strongly associated with kidney diseases. We investigated the role of ApoL1 variants in monocyte differentiation and eicosanoid production in macrophages, as activated tissue macrophages in kidney might contribute to kidney injury. In human monocyte THP-1 cells, transient overexpression of ApoL1 (G0, G1, G2) by transfection resulted in a 5- to 11-fold increase in CD14 and CD68 gene expression, similar to that seen with phorbol-12-myristate acetate treatment. All ApoL1 variants caused monocytes to differentiate into atypical M1 macrophages with marked increase in M1 markers CD80, TNF, IL1B, and IL6 and modest increase in the M2 marker CD163 compared with control cells. ApoL1-G1 transfection induced additional CD206 and TGFB1 expression, and ApoL1-G2 transfection induced additional CD204 and TGFB1 expression. Gene expression of prostaglandin E2 (PGE2) synthase and thromboxane synthase and both gene and protein expression of cyclooxygenase-2 (COX-2) were increased by ApoL1-G1 and -G2 variants compared with -G0 transfection. Higher levels of PGE2 and thromboxane B2, a stable metabolite of thromboxane A2, and transforming growth factor (TGF)-β1 were released into the supernatant of cultured THP-1 cells transfected with ApoL1-G1 and -G2, but not -G0. The increase in PGE2, thromboxane B2, and TGF-β1 was inhibited by COX-2-specific inhibitor CAY10404 but not by COX-1-specific inhibitor SC-560. These results demonstrate a novel role of ApoL1 variants in the regulation of monocyte differentiation and eicosanoid metabolism, which could modify the immune response and promote inflammatory signaling within the local targeted organs and tissues including the kidney.

Influence of citrate concentration on the activation of blood cells in an in vitro dialysis setup

Background

Regional citrate anticoagulation has been associated with enhanced biocompatibility in hemodialysis, but the optimal dose of citrate remains to be established. Here, we compared parameters related to cellular activation during in vitro dialysis, using two doses of citrate.

Methods

Human whole blood, anticoagulated with either 3 mM or 4 mM of citrate, was recirculated in an in vitro miniaturized dialysis setup. Complement (C3a-desArg), soluble platelet factor 4 (PF4), thromboxane B2 (TXB2), myeloperoxidase (MPO), as well as platelet- and red blood cell-derived extracellular vesicles (EV) were quantified during recirculation. Dialyzer fibers were examined by scanning electron microscopy after recirculation to assess the activation of clotting and the deposition of blood cells.

Results

Increases in markers of platelet and leukocyte activation, PF4, TXB2, and MPO were comparable between both citrate groups. Complement activation tended to be lower at higher citrate concentration, but the difference between the two citrate groups did not reach significance. A strong increase in EVs, particularly platelet-derived EVs, was observed during in vitro dialysis for both citrate groups, which was significantly less pronounced in the high citrate group at the end of the experiment. Assessment of dialyzer clotting scores after analysis of individual fibers by scanning electron microscopy revealed significantly lower scores in the high citrate group.

Conclusions

Our data indicate that an increase in the citrate concentration from 3 mM to 4 mM further dampens cellular activation, thereby improving biocompatibility. A concentration of 4 mM citrate might therefore be optimal for use in clinical practice.

Panax quinquefolius saponins combined with dual antiplatelet drug therapy alleviate gastric mucosal injury and thrombogenesis through the COX/PG pathway in a rat model of acute myocardial infarction

Objectives

Previous studies have found that Panax quinquefolius saponins (PQS) combined with dual antiplatelet therapy (DAPT) of aspirin and clopidogrel enhances antithrombotic effects while reducing gastric mucosal injury induced by DAPT. We investigated the effects of the combined drug therapy (PQS+DAPT) through the COX/PG pathways.

Methods

Acute myocardial infarction (AMI) was induced in Wistar rats by ligation of the left anterior descending (LAD) coronary artery, and the animals were randomly divided into Model, DAPT, and PQS+DAPT groups. Rats in the sham group did not undergo artery ligation. They were intragastrically treated for 14 days. Myocardial infarct size; myocardial pathology; platelet aggregation rate, CD62p activation, concentrations of thromboxane B₂ (TXB₂), 6-keto-PGF1α, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor (PAI), the TXB₂/6-keto-PGF1α ratio were measured. The ultrastructure of the gastric mucosa was observed by scanning electron microscopy. The expression of PGE₂ and 6-keto-PGF1α in gastric mucosa was measured by radioimmunoassay, and levels of COX-1, COX-2, and VEGF in gastric mucosa were assessed using immunohistochemistry.

Results

The addition of Panax quinquefolius saponins (PQS+DAPT) to standard DAPT therapy significantly decreased the myocardial infarct area, degree of myocardial lesions, TXB₂ and PAI levels, and the TXB₂/6-keto-PGF1α ratio, while increasing 6-keto-PGF1α and t-PA levels and reducing the degree of gastric mucosal injury. Expression of PGE₂, 6-keto-PGF1α, COX-2, and VEGF in the gastric mucosa was upregulated in the PQS+DAPT group compared with the standard DAPT group.

Conclusion

PQS increases the degree of DAPT inhibition of myocardial necrosis and antiplatelet effects in AMI rats, as well as reducing damage to the gastric mucosa caused by DAPT. The mechanism may be related to inhibition of TXB₂ and PAI activity and elevation of 6-keto-PGF1α and t-PA levels in blood, and may be associated with upregulated expression of COX-2, PGE₂, PGI₂, and VEGF in gastric tissue.

Kidney Transplantation in a Patient Lacking Cytosolic Phospholipase A2 Proves Renal Origins of Urinary PGI-M and TX-M

RATIONALE

The balance between vascular prostacyclin, which is antithrombotic, and platelet thromboxane A2, which is prothrombotic, is fundamental to cardiovascular health. Prostacyclin and thromboxane A2 are formed after the concerted actions of cPLA2α (cytosolic phospholipase A2) and COX (cyclooxygenase). Urinary 2,3-dinor-6-keto-PGF1α (PGI-M) and 11-dehydro-TXB2 (TX-M) have been taken as biomarkers of prostacyclin and thromboxane A2 formation within the circulation and used to explain COX biology and patient phenotypes, despite concerns that urinary PGI-M and TX-M originate in the kidney.

OBJECTIVE

We report data from a remarkable patient carrying an extremely rare genetic mutation in cPLA2α, causing almost complete loss of prostacyclin and thromboxane A2, who was transplanted with a normal kidney resulting in an experimental scenario of whole-body cPLA2α knockout, kidney-specific knockin. By studying this patient, we can determine definitively the contribution of the kidney to the productions of PGI-M and TX-M and test their validity as markers of prostacyclin and thromboxane A2 in the circulation.

METHODS AND RESULTS

Metabolites were measured using liquid chromatography-tandem mass spectrometry. Endothelial cells were grown from blood progenitors. Before kidney transplantation, the patient's endothelial cells and platelets released negligible levels of prostacyclin (measured as 6-keto-prostaglandin F1α) and thromboxane A2 (measured as TXB2), respectively. Likewise, the urinary levels of PGI-M and TX-M were very low. After transplantation and the establishment of normal renal function, the levels of PGI-M and TX-M in the patient's urine rose to within normal ranges, whereas endothelial production of prostacyclin and platelet production of thromboxane A2 remained negligible.

CONCLUSIONS

These data show that PGI-M and TX-M can be derived exclusively from the kidney without contribution from prostacyclin made by endothelial cells or thromboxane A2 by platelets in the general circulation. Previous work relying on urinary metabolites of prostacyclin and thromboxane A2 as markers of whole-body endothelial and platelet function now requires reevaluation.

Expression and Activity of COX-1 and COX-2 in Acanthamoeba sp.-Infected Lungs According to the Host Immunological Status

Little is known about the pathomechanism of pulmonary infections caused by Acanthamoeba sp. Therefore, the aim of this study was to determine whether Acanthamoeba sp. may affect the expression and activity of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), resulting in the altered levels of their main products, prostaglandins (PGE₂) and thromboxane B₂ (TXB₂), in lungs of immunocompetent or immunosuppressed hosts. Acanthamoeba sp. induced a strong expression of COX-1 and COX-2 proteins in the lungs of immunocompetent mice, which, however, did not result in significant differences in the expression of PGE₂ and TXB₂. Our immunohistochemical analysis showed that immunosuppression induced by glucocorticoids in Acanthamoeba sp.-infected mice caused a decrease in COX-1 and COX-2 (not at the beginning of infection) in lung tissue. These results suggest that similar to COX-2, COX-1 is an important mediator of the pathophysiology in experimental pulmonary acanthamoebiasis. We suggest that the signaling pathways important for Acanthamoeba sp. induction of lung infection might interact with each other and depend on the host immune status.

Human retinal endothelial cells and astrocytes cultured on 3-D scaffolds for ocular drug discovery and development

Topical ocular ketorolac improves the outcomes of severe retinopathy of prematurity and when administered with systemic caffeine, decreases the severity of oxygen-induced retinopathy. We tested the hypothesis that co-cultures of human retinal endothelial cells (HRECs) and human retinal astrocytes (HRAs) on 3-dimensional (3-D) hydrogel scaffolds is a more representative biomimetic paradigm of the blood-retinal-barrier (BRB) than 2-D cultures, and should be utilized for preclinical drug discovery and development. Mono- and co-cultures of HRECs and HRAs were treated with standard doses of ketorolac, ibuprofen, and/or caffeine, and exposed to hyperoxia, intermittent hypoxia (IH), or normoxia on 2-D surfaces or 3-D biodegradable hydrogel scaffolds (AlgiMatrix or Geltrex). Media and cells were collected at 72h post treatment for arachidonic acid metabolites. Cells cultured on 3-D scaffolds exhibited less oxidative stress and variability in drug responses. HRAs enhanced the responses of HRECs to drugs and changes in oxygen environment. PGE2 and PGI2 were the predominant prostanoids produced in response to IH, reflecting COX-2 immunoreactivity. We conclude that HRECs and HRAs co-cultured on 3-D scaffolds may recapitulate drug responses of the dynamic BRB and therefore should be implemented for preclinical ocular drug discovery and development.

The impact of vitamin C on the relationship among inflammation, lipid peroxidation and platelet activation during analgesic nephropathy in rats

BACKGROUND

Oxidative stress and inflammation are involved in the pathogenesis of paracetamol-induced renal damage. This study examines the relationship between 8-iso-prostaglandin F2α (8-iso-PGF2α) and platelet activation as well as the relative contribution of the pro-inflammatory markers interleukin (IL)-1β and tumor necrosis factor-α (TNF-α) in enhanced 8-iso-PGF2α biosynthesis, as a complementary onset during analgesic nephropathy induced by chronic treatment with paracetamol. The protective effects of vitamin C on the aforementioned settings are also investigated.

METHODS

Analgesic nephropathy was induced in Wistar rats. Renal function markers and the activity of antioxidant enzymes were determined spectrophotometrically. Immunoassays were used to measure the pro-inflammatory markers and the markers of lipid peroxidation and platelet activation.

RESULTS

The chronic treatment with paracetamol led to renal dysfunction, represented by the elevation of plasma urea and creatinine and the decline in the enzymatic antioxidant status, but did not cause a significant increase in TNF-α and IL-1β. The paracetamol-induced lipid peroxidation and enhanced production of 8-iso-PGF2α was not sufficient to cause changes in platelet activation represented by the level of 11-dehydro thromboxane B2.

CONCLUSIONS

Our results suggest that oxidative stress cannot circumvent the need of stimulation by circulatory cytokines in order to induce inflammatory response and changes in platelet activation during analgesic nephropathy. Vitamin C proved to be beneficial in restoring the renal function markers to normal, increasing the renal enzymatic antioxidant potential, inhibiting lipid peroxidation, and lowering cytokine production and 11-dehydro thromboxane B2 excretion. The observed effects of vitamin C offer support for its potential use as protective treatment in cases of chronic paracetamol overdose.

Long chain fatty acids and related pro-inflammatory, specialized pro-resolving lipid mediators and their intermediates in preterm human milk during the first month of lactation

This study aimed to measure longitudinal quantities of the long chain fatty acids, their biologically active terminal metabolites and related intermediates (also called oxylipins) in preterm human milk expressed during the first month of lactation. In a prospective cohort, breast milk was collected throughout the first month of lactation in 30 women who delivered preterm infants. Eighteen bioactive lipids and their intermediates were quantified via solid phase extraction and LC-MS/MS. Analysis by GC-FID quantified the fatty acid precursors. Arachidonic acid (ARA) and docosahexaenoic acid (DHA) milk concentrations significantly declined throughout the first month. Oxylipin concentrations did not change during lactation. Positive associations existed between ARA and thromboxane B2, eicosapentaenoic acid and 18-hydroxyeicosapentaenoic acid, and between DHA and PDX and 14- and 17-hydroxydocosahexaenoic acids. DHA concentrations were 1.5 times higher and 14-HDHA was 1.7 times higher in milk from women taking DHA supplements. This investigation showed conditionally essential fatty acids, ARA and DHA, decreased in preterm milk, suggesting a need to supplement their intake for the breast milk-fed preterm infant. Positive associations between parent fatty acids, bioactive lipids and intermediates, as well as sensitivity of milk to maternal fatty acid intake, support consideration of a comprehensive approach to providing fatty acids for preterm infants through both maternal and infant supplementation.

A randomised controlled trial comparing a dietary antiplatelet, the water-soluble tomato extract Fruitflow, with 75 mg aspirin in healthy subjects

BACKGROUND/OBJECTIVES

Increasing numbers of food ingredients are gaining acknowledgement, via regulated health claims, of benefits to human health. One such is a water-soluble tomato extract, Fruitflow (FF), a dietary antiplatelet. We examined relative platelet responses to FF and to 75 mg aspirin (ASA) in healthy subjects.

SUBJECTS/METHODS

A total of 47 healthy subjects completed a double-blinded randomised controlled trial following a crossover design. Acute and 7-day treatments with 75 mg ASA were compared with control with and without concomitant FF, over a 5-h timecourse. Platelet aggregation response agonist, platelet thromboxane A2 release, plasma clotting times and time to form a primary haemostatic clot (PFA-100 closure time, TTC) were measured.

RESULTS

Administration of all treatments lowered platelet function and thromboxane A2 generation, and extended the TTC, relative to baseline (P<0.001) and to control (P<0.001). Plasma clotting times were not affected. A single 75 mg dose of ASA showed approximately equal efficacy to a dose of FF, whereas daily 75 mg ASA was approximately three times as effective after 7 days (P=0.002). Platelet responses were heterogenous with distinct weak and strong responder groups. Weak ASA responders retained a functional platelet response to collagen agonist and were responsive to FF. Concomitant FF and ASA did not lead to significant additive effects.

CONCLUSIONS

The suppression of platelet function observed after consuming FF is approximately one-third that of daily 75 mg ASA. The reversible action of FF renders it less likely to overextend the time to form a primary haemostatic clot than ASA, an important safety consideration for primary prevention.

The Effect of Chinese Herbal Medicine Formula mKG on Allergic Asthma by Regulating Lung and Plasma Metabolic Alternations

Asthma is a chronic inflammatory disorder of the airway and is characterized by airway remodeling, hyperresponsiveness, and shortness of breath. Modified Kushen Gancao Formula (mKG), derived from traditional Chinese herbal medicines (TCM), has been demonstrated to have good therapeutic effects on experimental allergic asthma. However, its anti-asthma mechanism remains currently unknown. In the present work, metabolomics studies of biochemical changes in the lung tissue and plasma of ovalbumin (OVA)-induced allergic asthma mice with mKG treatment were performed using ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Partial least squares–discriminate analysis (PLS−DA) indicated that the metabolic perturbation induced by OVA was reduced after mKG treatment. A total of twenty-four metabolites involved in seven metabolic pathways were identified as potential biomarkers in the development of allergic asthma. Among them, myristic acid (L3 or P2), sphinganine (L6 or P4), and lysoPC(15:0) (L12 or P16) were detected both in lung tissue and plasma. Additionally, l-acetylcarnitine (L1), thromboxane B2 (L2), 10-HDoHE (L10), and 5-HETE (L11) were first reported to be potential biomarkers associated with allergic asthma. The treatment of mKG mediated all of those potential biomarkers except lysoPC(15:0) (P16). The anti-asthma mechanism of mKG can be achieved through the comprehensive regulation of multiple perturbed biomarkers and metabolic pathways.

Xanthohumol from hop cones (Humulus lupulus L.) prevents ADP-induced platelet reactivity

Hop cones (Humulus lupulus L.), very rich source of phenolic compounds, possessing anticancer, antioxidant and anti-inflammatory activities, are considered as beneficial diet ingredients improving human health. In this study, the antiplatelet action of xanthohumol (XN), the principal flavonoid in hop cones, was investigated. XN significantly attenuated ADP-induced blood platelet aggregation (97.2 ± 35.7 AU for 6 μg/ml of XN vs. 120.4 ± 30.1 AU for 0.17% dimethyl sulfoxide (DMSO), p < 0.001) and significantly reduced the expression of fibrinogen receptor (activated form of GPIIbIIIa) on platelets' surface (47.6 ± 15.8 for 1.5 μg/ml XN, 44.6 ± 17.3% for 3 μg/ml XN vs. 54.5 ± 19.2% for control or 43.3 ± 18.4% for 6 μg/ml XN vs. 49.7 ± 19.4% for 0.17% DMSO, p < 0.05 or less). These findings suggest that the phenolic compounds originating from hops (XN) have a novel role as antiplatelet agents and can likely be used as dietary supplements in prophylactic approaches.

Panax quinquefolium saponin combined with dual antiplatelet drugs inhibits platelet adhesion to injured HUVECs via PI3K/AKT and COX pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Panax quinquefolium saponin (PQS) is the active component extracted from traditional Chinese medicine Panax quinquefolius L. and has been widely used as a supplement to dual antiplatelet drugs (DA) for treatment of coronary artery disease (CAD) for two decades; however, the efficacy of PQS combined with DA against platelet adhesion to endothelial cells (ECs), an essential step in thrombosis, remains unclear.

AIM OF THE STUDY

To compare PQS combined with DA and DA alone in inhibiting platelet adhesion to injured human umbilical vein endothelial cells (HUVECs) and to explore the possible mechanisms focusing on PI3K/AKT, COX-2/6-keto-PGF_1α, and COX-1/TXB₂ pathways.

METHODS

HUVECs injured by oxidized low-density lipoprotein (ox-LDL) were randomly allocated into control, model, DA, PQS+DA (P+DA), LY294002 (a PI3K inhibitor)+DA (L+DA), and LY294002+PQS+DA (LP+DA) groups. HUVEC apoptosis, platelet adhesion to injured HUVECs, and platelet CD62p expression were assayed by fluorescence activated cell sorting (FACS). The concentrations of 6-keto-PGF_1α and TXB₂ in the supernatant were measured by radioimmunoassay. Protein expression of phosphorylated-PI3K, PI3K, phosphorylated-AKT, AKT, COX-1, and COX-2 in both platelets and HUVECs was evaluated by western blot.

RESULTS

Compared to DA alone, PQS combined with DA reduced platelet adhesion to HUVECs and HUVEC apoptosis more potently, increased the concentration of supernatant 6-keto-PGF_1α and up-regulated phospho-AKT protein in HUVECs. LY294002 mitigated the effects of PQS on HUVEC apoptosis and platelet adhesion.

CONCLUSIONS

These findings show that PQS as a powerful supplement to DA, attenuated HUVEC apoptosis and improved the DA-mediated reduction of platelet adhesion to injured HUVECs and the underlying mechanisms may be associated with PI3K/AKT and COX pathways in HUVECs and platelets. PQS might provide a new complementary approach to improve the prognosis of thrombotic diseases in future.

Linoleic Acid, but not Oleic Acid, Upregulates Production of Interleukin-8 by Human Vascular Smooth Muscle Cells via Arachidonic Acid Metabolites Under Conditions of Oxidative Stress

OBJECTIVE

Preeclampsia is associated with oxidative stress, elevated plasma levels of linoleic acid (LA), and increased vascular smooth muscle expression of the inflammatory chemokine, interleukin-8 (IL-8). We hypothesized that increased levels of LA under conditions of oxidative stress would increased production of IL-8 by vascular smooth muscle cells because LA is the dietary precursor to arachidonic acid (AA) and its metabolites that mediate inflammation. We also hypothesized that oleic acid (OA), which is not metabolized to AA metabolites, would not increase IL-8 under conditions of oxidative stress.

METHODS

To test this hypothesis, we cultured placental arterial smooth muscle (PASM) cells with an oxidizing solution enriched with LA (OxLA) or OA (OxOA). Media concentrations were analyzed for IL-8 and AA metabolites. Inhibitors were used to block the lipoxygenase and cyclooxygenase pathways.

RESULTS

Exposure of cells to OxLA, but not to OxOA, significantly increased production of IL-8. OxLA also significantly increased production of AA metabolites. Nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway, blocked IL-8 and leukotriene B4 (LTB4) production induced by OxLA, whereas indomethacin, an inhibitor of the cyclooxygenase pathway, blocked IL-8, prostaglandin E2 (PGE2), and thromboxane B2 (TXB2) production. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated gene expression in PASM cells for representative lipoxygenase (LTB4) and cyclooxygenase (thromboxane) metabolite receptors.

CONCLUSION

PASM cells produced IL-8 in response to LA, but not OA, under conditions of oxidative stress. The IL-8 response was mediated by AA metabolites.

Anti-myocardial ischemia effect of Syringa pinnatifolia Hemsl. by inhibiting expression of cyclooxygenase-1 and -2 in myocardial tissues of mice

ETHNOPHARMACOLOGICAL RELEVANCE

The peeled stem of Syringa pinnatifolia Hemsl. (SP) is a traditional medicine in Inner Mongolia, China. The powder form of SP has been widely used for hundreds of years to relieve "He-Yi" related myocardial ischemia independently or in a traditional Chinese medicine preparation.

MATERIALS AND METHODS

SP was extracted with 95% and 80% ethanol. Chemical profiling was performed using HPLC-DAD and IT-TOF-ESI-MS analyses. Myocardial ischemia was produced by ligation of the left anterior descending (LAD) coronary artery to evaluate the anti-myocardial ischemia effect of SP. Male C57BL/6 mice were randomly divided into six groups (n=10 per group): a sham group, a model group, groups pretreated with SP at three dosages (20mg/kg, 40mg/kg, and 80mg/kg, intragastrically), and a positive control group (acetylsalicylic acid, ASA, 53mg/kg, intragastrically). Echocardiography was performed to determine heart function by measuring ejection fraction and fractional shortening. The levels of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in serum, and 6-keto-PGF1α and TXB2 both in plasma and in protein homogenate of myocardial tissue were also measured. The levels of cyclooxygenase (COX)-1 and -2 in the heart tissue and their expressions in mouse myocardial tissue were determined using Western blot and an immunofluorescence assay, respectively. Inflammatory cell infiltration and collagen deposition changes in the myocardial ischemic tissue were observed by pathological examination.

RESULTS

Intragastric pretreatment with SP produced a dose-dependent increase in cardiac function. SP at 80mg/kg significantly improved the EF (p<0.001) and FS (p<0.01) compared with the model group, as well as the levels of serum CK-MB and LDH decreased obviously (p<0.001), approaching those in the sham group. Besides, an obvious reduction in inflammatory cells infiltration and collagen deposition in the infarcted myocardial tissue was shown in each SP treatment group. In addition, SP increased 6-keto-PGF1α and decreased TXB2 levels in the plasma, whereas the opposite pattern was observed in the protein homogenate from the myocardial tissues at the infarction edge, but keeping balance the ratio of 6-keto-PGF1α and TXB2, which is better than ASA in plasma. The mechanisms is associated with the downregulated expressions of COX-1 (p<0.05) and COX-2 (p<0.001).

CONCLUSIONS

Ethanol extract of SP has a protective effect against myocardial ischemia via down regulation of COX-1 and COX-2 expression and by adjusting the ischemia-induced imbalance between 6-keto-PGF1α and TXB2. This study shows substantial evidence to support the clinical application of SP and indicates that such medicine has great potential for treating ischemia-induced heart disease.

[PHYSICAL EXERCISE TRAINING CAN- CELS CONSTITUTIVE NOS UNCOUPLING AND INDUCED VIOLATIONS OF CARDIAC HEMODYNAMICS IN HYPERTENSION (PART III)]

In the heart and heart mitochondria spontaneously hypertensive rats investigated the effect of physical exercise training (swimming in a moderate and excessive training mode) on the physiological indicators of cardiac hemodynamics and biochemical parameters that characterize the level of oxidative and nitrosative stress. The index of coupling Ca(2+)-dependent constitutive NO-synthases (cNOS = eNOS + nNOS) and biochemical index of dysfunction were calculated. It turned out that both modes of training is completely restored, and even exceed the reference values in untrained rats Wistar conjugate cNOS state and Ca(2+)-dependent synthesis of nitric oxide (NO). Intensity regime of exercise on the border of functionality have been ineffective for improving the functional state of the cardiovascular system and hypertension can provoke it further. Moderate physical training regime, on the contrary, improves the diastolic function of the heart due to an increase dP/dtmin, reducing end-diastolic pressure and a significant reduction in end-diastolic stiffness. Moderate exercise decreased peripheral resistance and cardiac afterload, as indicated by the decrease in end-systolic pressure and arterial stiffness, which contributed to more efficient and energy-saving of heart work. Improve physiological indicators of cardiac hemodynamics and functional state of the heart in moderate mode of training correlated with changes in both the calculated indices. Moderate mode of training is recommended as a simple physiological preconditioning method for the prevention of cardiac dysfunction, hypertension as a result of state uncoupling cNOS and the resulting excessive generation of superoxide and, conversely, inhibition of Ca(2+)-dependent synthesis of NO.

Amelioration of inflammation by phenolic rich methanolic extract of Ocimum sanctum Linn. leaves in isoproterenol induced myocardial infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. Oxidative stress and inflammation play vital role in the development of MI. The Indian basil or Tulsi (Ocimum sanctum Linn.), owing to its antioxidant potential, is used in the traditional system of Indian medicine to treat various disorders. We evaluated methanolic extract of O. sanctum (Tulsi) leaves on inflammation in isoproterenol (ISP) induced MI in rats. ISP-induced MI increased the levels of cardiac markers, phospholipases and phospholipid content. However, the same were reduced on pre-treatment with methanolic extract of O. sanctum leaves. The activities of 5-lipoxygenase and cycloxygenase-2 and levels of leukotriene B4 and thromboxane B2 were also elevated in ISP-treated rats, which were significantly decreased (P < 0.001) in extract pre-treated rats. The enhanced mRNA expressions of nuclear factor kappa-B, 5-lipoxygenase activating protein and receptor for leukotriene B4 on MI induction, were considerably reduced (P < 0.001) on extract pre-treatment. Histopathological analysis also confirmed the findings. The results also revealed the high phenolic content of methanolic extract of O. sanctum leaves. The study demonstrated that methanolic extract of Tulsi leaves can decrease inflammation in the cardiac tissue of ISP-induced MI in rats and its effect may be through downregulation of oxidative stress and arachidonic acid pathway. This cardioprotective effect may be due to the high phenolic content of methanolic extract of O. sanctum leaves.

Mechanisms in endocrinology: The spectrum of haemostatic abnormalities in glucocorticoid excess and defect

Glucocorticoids (GCs) target several components of the integrated system that preserves vascular integrity and free blood flow. Cohort studies on Cushing's syndrome (CS) have revealed increased thromboembolism, but the pathogenesis remains unclear. Lessons from epidemiological data and post-treatment normalisation time suggest a bimodal action with a rapid and reversible effect on coagulation factors and an indirect sustained effect on the vessel wall. The redundancy of the steps that are potentially involved requires a systematic comparison of data from patients with endogenous or exogenous hypercortisolism in the context of either inflammatory or non-inflammatory disorders. A predominant alteration in the intrinsic pathway that includes a remarkable rise in factor VIII and von Willebrand factor (vWF) levels and a reduction in activated partial thromboplastin time appears in the majority of studies on endogenous CS. There may also be a rise in platelets, thromboxane B2, thrombin-antithrombin complexes and fibrinogen (FBG) levels and, above all, impaired fibrinolytic capacity. The increased activation of coagulation inhibitors seems to be compensatory in order to counteract disseminated coagulation, but there remains a net change towards an increased risk of venous thromboembolism (VTE). Conversely, GC administered in the presence of inflammation lowers vWF and FBG, but fibrinolytic activity is also reduced. As a result, the overall risk of VTE is increased in long-term users. Finally, no studies have assessed haemostatic abnormalities in patients with Addison's disease, although these may present as a consequence of bilateral adrenal haemorrhage, especially in the presence of antiphospholipid antibodies or anticoagulant treatments. The present review aimed to provide a comprehensive overview of the complex alterations produced by GCs in order to develop better screening and prevention strategies against bleeding and thrombosis.

[Inhibitory effects and mechanisms of snake venom tripeptide pENW on platelet adhesion]

This study was designed to investigate inhibitory effects and possible mechanisms of snake venom tripeptide (pENW) on platelet adhesion in order to promote the development of a novel anti-platelet therapy. To study the inhibitory effects of pENW on platelet adhesion, washed platelets pre-incubated with pENW (116.5-466.2 μmol x L(-1)) were used to test the ability of platelet adhesion to fibrinogen. Effect of pENW on fibrin clot retraction was also tested. Effect of pENW on platelets viability was tested by MTT assay. Effect of pENW on reactive-oxygen species (ROS) levels of platelet was studied by flow cytometry assay. Calcium mobilization in Fura-2/AM-loaded platelets was monitored with a spectrofluorimeter. Cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP), thromboxane A2 (determined as its metabolite thromboxane B2) were measured using enzyme immunoassay kits. Akt, ERK and p38 phosphorylation were tested by Western blot. The results showed that pENW inhibited platelet adhesion and fibrin clot retraction in a concentration-dependent manner without cytotoxicity. Intracellular cGMP and cAMP in both resting and thrombin-activated platelets were increased by pENW. In addition, pENW attenuated intracellular Ca2+ mobilization and TXA2 production in platelets stimulated by thrombin. As shown by Western blot assay, Akt, ERK and p38 phosphorylation in thrombin-induced platelet were attenuated by pENW. However, inhibitory effects of pENW had nothing to do with ROS. Thus, pENW exhibited a significant inhibition on platelet adhesion to fibrinogen, which means pENW could block the first step of thrombosis as while as retard the more stable clot formation. The mechanisms of pENW on inhibition platelet adhesion might be related to instant regulations, such as protein kinases.

The Effect of Cadmium on COX-1 and COX-2 Gene, Protein Expression, and Enzymatic Activity in THP-1 Macrophages

The aim of this study was to examine the effects of cadmium in concentrations relevant to those detected in human serum on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) expression at mRNA, protein, and enzyme activity levels in THP-1 macrophages. Macrophages were incubated with various cadmium chloride (CdCl2) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM, and 2 μM CdCl2. The mRNA expression and protein levels of COXs were analyzed with RT-PCR and Western blotting, respectively. Prostaglandin E2 (PGE2) and stable metabolite of thromboxane B2 (TXB2) concentrations in culture media were determined using ELISA method. Our study demonstrates that cadmium at the highest tested concentrations modulates COX-1 and COX-2 at mRNA level in THP-1 macrophages; however, the lower tested cadmium concentrations appear to inhibit COX-1 protein expression. PGE2 and TXB2 production is not altered by all tested Cd concentrations; however, the significant stimulation of PGE2 and TXB2 production is observed when macrophages are exposed to both cadmium and COX-2 selective inhibitor, NS-398. The stimulatory effect of cadmium on COXs at mRNA level is not reflected at protein and enzymatic activity levels, suggesting the existence of some posttranscriptional, translational, and posttranslational events that result in silencing of those genes' expression.

Synthesis and antiplatelet activity of antithrombotic thiourea compounds: biological and structure-activity relationship studies

The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p) displayed IC₅₀ values ranging from 29 to 84 µM with direct influence over in vitro PGE₂ and TXA₂ formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE₂ and TXB₂ production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

Acute restraint stress induces endothelial dysfunction: role of vasoconstrictor prostanoids and oxidative stress

We hypothesized that acute stress would induce endothelial dysfunction. Male Wistar rats were restrained for 2 h within wire mesh. Functional and biochemical analyses were conducted 24 h after the 2-h period of restraint. Stressed rats showed decreased exploration on the open arms of an elevated-plus maze (EPM) and increased plasma corticosterone concentration. Acute restraint stress did not alter systolic blood pressure, whereas it increased the in vitro contractile response to phenylephrine and serotonin in endothelium-intact rat aortas. NG-nitro-l-arginine methyl ester (l-NAME; nitric oxide synthase, NOS, inhibitor) did not alter the contraction induced by phenylephrine in aortic rings from stressed rats. Tiron, indomethacin and SQ29548 reversed the increase in the contractile response to phenylephrine induced by restraint stress. Increased systemic and vascular oxidative stress was evident in stressed rats. Restraint stress decreased plasma and vascular nitrate/nitrite (NOx) concentration and increased aortic expression of inducible (i) NOS, but not endothelial (e) NOS. Reduced expression of cyclooxygenase (COX)-1, but not COX-2, was observed in aortas from stressed rats. Restraint stress increased thromboxane (TX)B(2) (stable TXA(2) metabolite) concentration but did not affect prostaglandin (PG)F2α concentration in the aorta. Restraint reduced superoxide dismutase (SOD) activity, whereas concentrations of hydrogen peroxide (H(2)O(2)) and reduced glutathione (GSH) were not affected. The major new finding of our study is that restraint stress increases vascular contraction by an endothelium-dependent mechanism that involves increased oxidative stress and the generation of COX-derived vasoconstrictor prostanoids. Such stress-induced endothelial dysfunction could predispose to the development of cardiovascular diseases.

Frataxin deficiency increases cyclooxygenase 2 and prostaglandins in cell and animal models of Friedreich's ataxia

An inherited deficiency of the mitochondrial protein frataxin causes Friedreich's ataxia (FRDA); the mechanism by which this deficiency triggers neuro- and cardio-degeneration is unclear. Microarrays of neural tissue of animal models of the disease showed decreases in antioxidant genes, and increases in inflammatory genes. Cyclooxygenase (COX)-derived oxylipins are important mediators of inflammation. We measured oxylipin levels using tandem mass spectrometry and ELISAs in multiple cell and animal models of FRDA. Mass spectrometry revealed increases in concentrations of prostaglandins, thromboxane B2, 15-HETE and 11-HETE in cerebellar samples of knockin knockout mice. One possible explanation for the elevated oxylipins is that frataxin deficiency results in increased COX activity. While constitutive COX1 was unchanged, inducible COX2 expression was elevated over 1.35-fold (P < 0.05) in two Friedreich's mouse models and Friedreich's lymphocytes. Consistent with higher COX2 expression, its activity was also increased by 58% over controls. COX2 expression is driven by multiple transcription factors, including activator protein 1 and cAMP response element-binding protein, both of which were elevated over 1.52-fold in cerebella. Taken together, the results support the hypothesis that reduced expression of frataxin leads to elevation of COX2-mediated oxylipin synthesis stimulated by increases in transcription factors that respond to increased reactive oxygen species. These findings support a neuroinflammatory mechanism in FRDA, which has both pathomechanistic and therapeutic implications.

Effects of danshensu on platelet aggregation and thrombosis: in vivo arteriovenous shunt and venous thrombosis models in rats

Danshensu, a type of dihydroxyphenyl lactic acid, is one of the most abundant active phenolic acids in the dried root of Salvia miltiorrhizae (Lamiaceae)--widely used traditional Chinese medicine. The effects of danshensu on platelet aggregation and thrombus formation in rats were examined using various methods. It was found that danshensu significantly reduced thrombus weight in 2 experimental thrombosis models; dose-dependent inhibition of adenosine diphosphate (ADP) and arachidonic acid (AA)-induced platelet aggregation occurred in normal and blood stasis-induced rats; Danshensu also significantly mitigated blood viscosity, plasma viscosity and hematocrit levels. Moreover, danshensu significantly inhibited venous thrombosis-induced expression of cyclooxygenases-2 (COX-2) rather than cyclooxygenases-1(COX-1) in the venous walls, down regulated thromboxane B2 (TXB2) and up regulated 6-keto prostaglandin F1α (6-keto-PGF1α), normalizing the TXB2/6-keto-PGF1α ratio. In addition, danshensu did not induce gastric lesions and even had protective effects on aspirin-induced ulcer formation at doses as high as 60 mg/kg. These findings suggest that the antithrombotic and antiplatelet aggregation effects of danshensu are attributed to its highly selective inhibition of COX-2 and ability to normalize the thromboxane A2(TXA2)/prostacyclin(PGI2) balance. These findings suggest that danshensu have great prospects in antithrombotic and antiplatelet therapy.

[Atorvastatin inhibits platelet aggregation and activation following carotid balloon injury in cholesterol-fed rabbits]

OBJECTIVE

To investigate the effect of atorvastatin on platelet aggregation and activation in the acute phase following balloon-induced carotid artery injury in rabbits fed cholesterol-enriched diet.

METHODS

Thirty rabbits were randomly divided into 5 equal groups, namely control group, high-cholesterol group, model group, low-dose (5 mg/kg daily) atorvastatin group, and high-dose (10 mg/kg daily) atorvastatin group. Platelet aggregation rate was measured in the rabbits by turbidimetric platelet aggregometry, and the changes of serum P-selectin and thromboxane B2 (TXB2) levels were detected with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with those in the control group, serum P-selectin level increased significantly (P<0.01) but platelet aggregation rate and TXB2 level exhibited no obvious changes in high-cholesterol group. After carotid artery balloon injury, P-selectin and TXB2 levels and platelet aggregation significantly increased in cholesterol-fed rabbits, reaching the peak level at 24 h after the injury (P<0.01). Compared with the model group, low-dose atorvastatin treatment significantly decreased P-selectin and TXB2 levels and inhibited platelet aggregation in cholesterol-fed rabbits following carotid artery balloon injury (P<0.01), and such effects of atorvastatin were more prominent at a higher daily dose of 10 mg/kg (P<0.05).

CONCLUSIONS

Carotid artery balloon injury in rabbits fed cholesterol-enriched diet can induce platelet activation and aggregation, which reaches the peak level at 24 h after balloon injury and can be dose-dependently inhibited by atorvastatin in the acute phase following the injury.

Vibrio vulnificus MO6-24/O lipopolysaccharide stimulates superoxide anion, thromboxane B₂, matrix metalloproteinase-9, cytokine and chemokine release by rat brain microglia in vitro

Although human exposure to Gram-negative Vibrio vulnificus (V. vulnificus) lipopolysaccharide (LPS) has been reported to result in septic shock, its impact on the central nervous system's innate immunity remains undetermined. The purpose of this study was to determine whether V. vulnificus MO6-24/O LPS might activate rat microglia in vitro and stimulate the release of superoxide anion (O₂⁻), a reactive oxygen species known to cause oxidative stress and neuronal injury in vivo. Brain microglia were isolated from neonatal rats, and then treated with either V. vulnificus MO6-24/O LPS or Escherichia coli O26:B6 LPS for 17 hours in vitro. O₂⁻ was determined by cytochrome C reduction, and matrix metalloproteinase-2 (MMP-2) and MMP-9 by gelatinase zymography. Generation of cytokines tumor necrosis factor alpha (TNF-α), interleukin-1 alpha (IL-1α), IL-6, and transforming growth factor-beta 1 (TGF-β1), chemokines macrophage inflammatory protein (MIP-1α)/chemokine (C-C motif) ligand 3 (CCL3), MIP-2/chemokine (C-X-C motif) ligand 2 (CXCL2), monocyte chemotactic protein-1 (MCP-1)/CCL2, and cytokine-induced neutrophil chemoattractant-2alpha/beta (CINC-2α/β)/CXCL3, and brain-derived neurotrophic factor (BDNF), were determined by specific immunoassays. Priming of rat microglia by V. vulnificus MO6-24/O LPS in vitro yielded a bell-shaped dose-response curve for PMA (phorbol 12-myristate 13-acetate)-stimulated O₂⁻ generation: (1) 0.1-1 ng/mL V. vulnificus LPS enhanced O₂⁻ generation significantly but with limited inflammatory mediator generation; (2) 10-100 ng/mL V. vulnificus LPS maximized O₂⁻ generation with concomitant release of thromboxane B2 (TXB2), matrix metalloproteinase-9 (MMP-9), and several cytokines and chemokines; (3) 1000-100,000 ng/mL V. vulnificus LPS, with the exception of TXB2, yielded both attenuated O₂⁻ production, and a progressive decrease in MMP-9, cytokines and chemokines investigated. Thus concentration-dependent treatment of neonatal brain microglia with V. vulnificus MO6-24/O LPS resulted in a significant rise in O₂⁻ production, followed by a progressive decrease in O₂⁻ release, with concomitant release of lactic dehydrogenase (LDH), and generation of TXB2, MMP-9, cytokines and chemokines. We hypothesize that the inflammatory mediators investigated may be cytotoxic to microglia in vitro, by an as yet undetermined autocrine mechanism. Although V. vulnificus LPS was less potent than E. coli LPS in vitro, inflammatory mediator release by the former was clearly more efficacious. Finally, we hypothesize that should V. vulnificus LPS gain entry into the CNS, it would be possible that microglia might become activated, resulting in high levels of O₂⁻ as well as neuroinflammatory TXB2, MMP-9, cytokines and chemokines.

Effect of Ocimum basilicum L. on cyclo-oxygenase isoforms and prostaglandins involved in thrombosis

ETHNOPHARMACOLOGICAL RELEVANCE

Ocimum basilicum L. (OBL) is a plant used in traditional Uyghur medicine for the treatment and prevention of cardiovascular disease. In previous studies we had found an antihypertensive and antithrombotic effect suggestive of an effect on prostaglandins, which we attempt to document here.

MATERIALS AND METHODS

6-keto-PGF1α, the metabolite of prostacyclin, and PGE2 were measured in the supernatant of human umbilical vein endothelial cells (HUVEC) and basal or LPS-stimulated mouse coeliac macrophage cultures exposed to OBL ethanol (OBL-E) extracts and petroleum ether, chloroform, ethylacetate and butanol (PE, C, EA, B) fractions. In addition, 6-keto-PGF1α and thromboxane B2 (TXB2) were measured in a rat model of thromboangiitis obliterans exposed or not to OBL.

RESULTS

Short-term exposure to OBL-E dose-dependently increased 6-keto-PGF1α from HUVEC, and long-term (24h) exposure decreased it. OBL-C and OBL-B increased 6-keto-PGF1α, whereas the other fractions tended to decrease it after 24h exposure. The extract and all fractions decreased basal and stimulated PGE2 production, but only OBL-EA and OBL-B reduced PGE2 in stimulated cultures to concentrations below the unstimulated values (P<0.05). In vivo OBL increased 6-keto-PGF1α and decreased TXB2.

CONCLUSION

OBL and its extracts increased 6-keto-PGF1α and reduced PGE2 and TXB2 production in a dose and time-related manner. This could indicate simultaneous inhibition of COX-2 and stimulation of endothelial COX-1. The butanol fraction seemed most promising in this respect.

Long-chain fatty alcohols from evening primrose oil inhibit the inflammatory response in murine peritoneal macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Evening primrose (Oenothera biennis L., Onagraceae) is a wild medicinal plant of Central American origin that is now one of the most widely used herbal medicines in different parts of the world. Oil extracted from it seeds is traditionally used in the treatment of eczema, asthma, rheumatoid arthritis, breast problem, premenstrual and menopausal syndrome, all they have an inflammatory component. The present study demonstrates the in vitro anti-inflammatory effect of long-chain fatty alcohols, minor compounds isolated from Evening primrose oil (EPO).

MATERIAL AND METHODS

A mixture of long chain fatty alcohols (LCFAs) was isolated from the non-triacylglycerol fraction of the EPO. Hexacosanol (C26OH: 38.65%), tetracosanol (C24OH: 31.59%), docosanol (C22OH: 11.36%) and octocosanol (C28OH: 7.64%), were the major constituents, identified and quantified by GC and GC-MS. LCFA was tested with LPS stimulated murine peritoneal macrophage. This fraction, significantly and dose-dependently decreased nitric oxide production induced by LPS (P<0.001) and the inhibitory effect seems to be consequence of an action at the level of the inducible nitric-oxide synthethase (iNOS) gene enzyme expression rather than to a direct inhibitory action on enzyme activity. The release of PLA2 and TXB2 also was significantly inhibited by LCFAs (P<0.001) although LCFAs did not affect to PGE2 generation, however the western blot assay showed that LCFAs reduced cyclooxygenase-2 enzyme gene expression at all doses assayed. In the same way, the secretion of inflammatory cytokines interleukin 1β (IL-1β) and tumour necrosis factor α (TNF-α) from LPS-stimulated murine macrophage, were also significantly reduced (P<0.001).

CONCLUSION

These results demonstrates the anti-inflammatory activity of LCFAs, providing an additional value about the role of bioactive minor compounds in the beneficial effect of EPO and supports its traditional uses in inflammatory processes management.

Eicosanoid post-mortem induction in kidney tissue is prevented by microwave irradiation

Previously, we, and others, have demonstrated a rapid and significant post-mortem increase in brain prostanoid (PG) levels analyzed without microwave fixation, and this is not the result of PG trapping or destruction in microwave-irradiated brain tissue. In the present study, we demonstrate a dramatic increase in kidney eicosanoid levels when analyzed without microwave fixation which was mainly accounted for by the 142-, 81-, and 62-fold increase in medullary 6-ketoPGF1α, PGE2, and PGF2α, levels, respectively, while PGD2 and TXB2 levels were increased ~7-fold. Whole kidney and cortex PG were also significantly increased in non-microwaved tissue, but at lesser extent. Arachidonic acid and the lipoxygenase products hydroxyeicosatetraenoic acids (HETE) were also induced in whole kidney, cortex, and medulla 1.5- to 5.5-fold depending upon tissue and metabolite. Cyclooxygenase inhibition with indomethacin decreased PG mass in non-microwaved tissue to basal levels, however HETE and arachidonic acid were not decreased. These data demonstrate the critical importance of kidney tissue fixation to limiting artifacts during kidney eicosanoid analysis.

Modulation of platelet aggregation-related eicosanoid production by dietary F-fucoidan from brown alga Laminaria japonica in human subjects

Laminaria japonica is traditionally eaten in Japan as a beneficial food for thrombosis. The alga contains two specific ingredients, a xanthophyll fucoxanthin (FX) and a polysaccharide, F-fucoidan (FD). The aim of the present study was to investigate whether FX or FD exhibited anti-thrombotic effects. For this purpose, three types of capsules, containing 1 mg FX, 400 mg fucoidan, and both, were prepared from the alga and administered to volunteers for 5 weeks. The dose of FD or FD+FX significantly shortened lysis time (LT) of the thrombus measured by a global thrombosis test in the blood, but FX did not. Examining the mechanism, dietary FD increased H2O2 and the secretion of prostacyclin (PGI2), a potent inhibitor of platelet aggregation, in the blood, although FD was under the detection limit in the blood, determining with its monoclonal antibody. Furthermore, in mouse experiments, dietary FD was totally excreted into the faeces and was not incorporated into the blood. We then employed a co-culture system of a Caco-2 cell monolayer with fresh human blood. The addition of FD to Caco-2 cells stimulated the expression of NADPH oxidase 1 (NOX1) and dual oxidase 2 (DUOX2) mRNA and secreted H2O2 onto the blood side accompanied by a significant increase in serum PGI2 production. These effects were invalidated by the combined addition of FD with its monoclonal antibody. The results suggested that dietary FD stimulated the expression of H2O2-producing enzymes in intestinal epithelial cells and released H2O2 into the blood, which played a signalling role to increase PGI2 production and then shortened LT for thrombi.

[Effects of transcutaneous electrical acupoint stimulation of "Zusanli" (ST 36) on gastric mucosal injury in exercise stress-induced gastric ulcer rats]

OBJECTIVE

To observe the effect of transcutaneous electrical acupoint stimulation(TEAS) of "Zusanli" (ST 36) on gastric mucosal injury in rats with exercise stress-induced gastric ulcer.

METHODS

Twenty-four SD rats were randomly and equally divided into normal control, model and TEAS groups. Gastric ulcer model was established by forcing the rat to run on a treadmill (15 m/min) till exhaustion, once daily continuously for 15 days. TEAS was applied to bilateral "Zusanli" (ST 36) for 30 min, once daily for 15 days. Behavior changes (crossing and rearing scores) were assessed using open-field test. The ulcer index (UI) of the gastric mucosa was measured by giving the mottling bleeding, streak-like hemorrhage and lesion width with scores according to Guth's method. Contents of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) and thromboxane B 2 (TXB2) of gastric mucosal tissue were measured using radioimmunoassay.

RESULTS

Compared with the normal group, the levels of crossing and rearing levels in open-field tests, and the duration of forced treadmill running exhaustion, gastromocosal 6-keto-PGF1alpha and TXB2 contents in the model group were obviously reduced (P < 0.01), while the UI of model group was obviously increased (P < 0.01). In comparison with the model group, the scores of crossing and rearing in open-field tests and the duration of forced treadmill running exhaustion and gastromocosal 6-keto-PGF1alpha and TXB2 contents of TEAS group were significantly increased (P < 0.05), and the UI of TEAS group was obviously decreased (P < 0.05).

CONCLUSION

TEAS of "Zusanli" (ST 36) can protect gastric mucosa from injury in exercise stress-induced gastric ulcer rats.

Blocking of thromboxane A₂ receptor attenuates airway mucus hyperproduction induced by cigarette smoke

Cigarette smoking is one of the risk factors for chronic obstructive pulmonary disease (COPD). In this study, we investigated the effects of thromboxane A2 (TxA2) receptor antagonists on airway mucus production induced by cigarette smoke. Rats were exposed to cigarette smoke 1h/day, 6 days/week for 4 weeks. Seratrodast (2, 5, 10mg/kg day) was administered intragastrically prior to smoke exposure. Thromboxane B2 (TxB2) in the bronchoalveolar lavage fluid and lung tissues was determined by enzyme immunoassay. Airway mucus production was determined by alcin-blue/periodic acid sthiff (AB-PAS) staining, Muc5ac immunohistochemical staining, and RT-PCR. The phosphorylation of ERK and p38 was evaluated by Western blotting. Seratrodast reduced the overproduction of TxB2 in both bronchoalveolar lavage fluid and lung tissues. Cigarette smoke exposure markedly increased AB/PAS-stained goblet cells and rat Muc5ac expression in the airway, which was significantly attenuated by seratrodast administration. The induced phosphorylation of ERK and p38 was also attenuated by seratrodast. TxA2 receptor antagonist could reduce Muc5ac production induced by cigarette smoke in vivo, possibly through the mitogen-activated protein kinases (MAPK) signaling pathway.

Inhibition of sphingosine kinase-2 in a murine model of lupus nephritis

Sphingosine-1-phosphate (S1P), a potent bioactive lipid, is emerging as a central mediator in inflammation and immune responses. We have previously implicated S1P and its synthetic enzyme sphingosine kinase (SK) in inflammatory and autoimmune disorders, including inflammatory bowel disease and rheumatoid arthritis. Generation of S1P requires phosphorylation of sphingosine by SK, of which there are two isoforms. Numerous studies have implicated SK1 in immune cell trafficking, inflammation and autoimmune disorders. In this study, we set out to determine the role of SK and S1P in lupus nephritis (LN). To this end, we examined S1P and dihydro-S1P (dh-S1P) levels in serum and kidney tissues from a mouse model of LN. Interestingly dh-S1P was significantly elevated in serum and kidney tissue from LN mice, which is more readily phosphorylated by SK2. Therefore, we employed the use of the specific SK2 inhibitor, ABC294640 in our murine model of LN. Treatment with ABC294640 did not improve vascular or interstitial pathology associated with LN. However, mice treated with the SK2 inhibitor did demonstrate decreases in glomerular pathology and accumulation of B and T cells in the spleen these were not statistically different from lpr mice treated with vehicle. LN mice treated with ABC294640 did not have improved urine thromboxane levels or urine proteinuria measurements. Both S1P and dh-S1P levels in circulation were significantly reduced with ABC294640 treatment; however, dh-S1P was actually elevated in kidneys from LN mice treated with ABC294640. Together these data demonstrate a role for SKs in LN; however, they suggest that inhibition of SK1 or perhaps both SK isoforms would better prevent elevations in S1P and dh-S1P and potentially better protect against LN.

Atorvastatin protects obese mice against hepatic ischemia-reperfusion injury by Toll-like receptor-4 suppression and endothelial nitric oxide synthase activation

BACKGROUND AND AIM

Steatosis accentuates the severity of hepatic ischemia-reperfusion injury (IRI). 3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors ("statins") protect the heart and brain against post-ischemic injury, without necessarily lowering serum cholesterol. We tested whether 10-day or 1-day atorvastatin administration protects livers with fatty change or non-alcoholic steatohepatitis (NASH) against IRI.

METHODS

Mice with dietary or genetic simple steatosis (SS) or NASH were subjected to 60 min of partial hepatic ischemia/24-h reperfusion, with/without atorvastatin administered with food (5 mg/kg body weight) for 10 days, or injected intravenously (5 mg/kg) 24 h before ischemia. Liver injury, Toll-like receptor-4 (TLR4), cytokines/chemokines, endothelial nitric oxide synthase (eNOS), activation and thromboxane B2 production were determined.

RESULTS

Atorvastatin conferred 70-90% hepatic protection against IRI in obese animals with SS or NASH, in which IRI was accentuated twofold to fivefold. IRI markedly upregulated TLR4 and activated nuclear factor-κB (NF-κB); atorvastatin abrogated these effects, as well as activating eNOS. Atorvastatin dampened the post-ischemic induction of thromboxane B2, macrophage inflammatory protein-1a, monocyte chemotactic protein-1, tumor necrosis factor-α, interleukin (IL)-12 p40, γ-interferon, IL-6, and adhesion molecules (vascular cell adhesion molecule-1, E-selectin, vascular endothelial-cadherin), and reduced macrophage and neutrophil recruitment. There was no reduction in serum cholesterol that could explain these effects, and hepatic cholesterol was normal in these mice. A single 24-h injection of atorvastatin conferred equivalent hepatoprotection.

CONCLUSION

Statins exert major hepatoprotection against IRI in lean, fatty, and NASH livers that is not due to cholesterol removal. Rather, statins downregulate TLR4 to prevent NF-κB activation, with resultant suppression of adhesion molecules, chemokines/cytokines, and thromboxane B2 production. Short-term statin treatment is an effective, readily-available preventive agent against hepatic IRI, irrespective of obesity and fatty liver disease.

Gabapentin's minimal action on markers of rat brain arachidonic acid metabolism agrees with its inefficacy against bipolar disorder

In rats, FDA-approved mood stabilizers used for treating bipolar disorder (BD) selectively downregulate brain markers of the arachidonic acid (AA) cascade, which are upregulated in postmortem BD brain. Phase III clinical trials show that the anticonvulsant gabapentin (GBP) is ineffective in treating BD. We hypothesized that GBP would not alter the rat brain AA cascade. Chronic GBP (10 mg/kg body weight, injected i.p. for 30 days) compared to saline vehicle did not significantly alter brain expression or activity of AA-selective cytosolic phospholipase A(2) (cPLA(2)) IVA or secretory (s)PLA(2) IIA, activity of cyclooxygenase-2, or prostaglandin E(2) or thromboxane B(2) concentrations. Plasma esterified and unesterified AA concentration was unaffected. These results, taken with evidence of an upregulated AA cascade in the BD brain and that approved mood stabilizers downregulate the rat brain AA cascade, support the hypothesis that effective anti-BD drugs act by targeting the brain AA cascade whereas ineffective drugs (such as GBP) do not target this pathway, and suggest that the rat model might be used for screening new anti-BD drugs.

Lamotrigine blocks NMDA receptor-initiated arachidonic acid signalling in rat brain: implications for its efficacy in bipolar disorder

An up-regulated brain arachidonic acid (AA) cascade and a hyperglutamatergic state characterize bipolar disorder (BD). Lamotrigine (LTG), a mood stabilizer approved for treating BD, is reported to interfere with glutamatergic neurotransmission involving N-methyl-d-aspartate receptors (NMDARs). NMDARs allow extracellular calcium into the cell, thereby stimulating calcium-dependent cytosolic phospholipase A2 (cPLA2) to release AA from membrane phospholipid. We hypothesized that LTG, like other approved mood stabilizers, would reduce NMDAR-mediated AA signalling in rat brain. An acute subconvulsant dose of NMDA (25 mg/kg) or saline was administered intraperitoneally to unanaesthetized rats that had been treated p.o. daily for 42 d with vehicle or a therapeutically relevant dose of LTG (10 mg/kg.d). Regional brain AA incorporation coefficients k* and rates J in, and AA signals, were measured using quantitative autoradiography after intravenous [1-14C]AA infusion, as were other AA cascade markers. In chronic vehicle-treated rats, acute NMDA compared to saline increased k* and J in in widespread regions of the brain, as well as prostaglandin (PG)E2 and thromboxane B2 concentrations. Chronic LTG treatment compared to vehicle reduced brain cyclooxygenase (COX) activity, PGE2 concentration, and DNA-binding activity of the COX-2 transcription factor, NF-κB. Pretreatment with chronic LTG blocked the acute NMDA effects on AA cascade markers. In summary, chronic LTG like other mood stabilizers blocks NMDA-mediated signalling involving the AA metabolic cascade. Since markers of the AA cascade and of NMDAR signalling are up-regulated in the post-mortem BD brain, mood stabilizers generally may be effective in BD by dampening NMDAR signalling and the AA cascade.

PPARα activation improves endothelial dysfunction and reduces fibrosis and portal pressure in cirrhotic rats

BACKGROUND & AIMS

Peroxisome proliferator-activated receptor α (PPARα) is a transcription factor activated by ligands that regulates genes related to vascular tone, oxidative stress, and fibrogenesis, pathways implicated in the development of cirrhosis and portal hypertension. This study aims at evaluating the effects of PPARα activation with fenofibrate on hepatic and systemic hemodynamics, hepatic endothelial dysfunction, and hepatic fibrosis in CCl(4)-cirrhotic rats.

METHODS

Mean arterial pressure (MAP), portal pressure (PP), and portal blood flow (PBF) were measured in cirrhotic rats treated with oral fenofibrate (25mg/kg/day, n=10) or its vehicle (n=12) for 7 days. The liver was then perfused and dose-relaxation curves to acetylcholine (Ach) were performed. We also evaluated Sirius Red staining of liver sections, collagen-I mRNA expression, and smooth muscle actin (α-SMA) protein expression, cyclo-oxygenase-1 (COX-1) protein expression, and cGMP levels in liver homogenates, and TXB(2) production in perfusates. Nitric oxide (NO) bioavailability and eNOS activation were measured in hepatic endothelial cells (HEC) isolated from cirrhotic rat livers.

RESULTS

CCl(4) cirrhotic rats treated with fenofibrate had a significantly lower PP (-29%) and higher MAP than those treated with vehicle. These effects were associated with a significant reduction in hepatic fibrosis and improved vasodilatory response to acetylcholine. Moreover, a reduction in COX-1 expression and TXB(2) production in rats receiving fenofibrate and a significant increase in NO bioavailability in HEC with fenofibrate were observed.

CONCLUSIONS

PPARα activation markedly reduced PP and liver fibrosis and improved hepatic endothelial dysfunction in cirrhotic rats, suggesting it may represent a new therapeutic strategy for portal hypertension in cirrhosis.

A role for adhesion and degranulation-promoting adapter protein in collagen-induced platelet activation mediated via integrin α(2) β(1)

BACKGROUND

Collagen-induced platelet activation is a key step in the development of arterial thrombosis via its interaction with the receptors glycoprotein (GP)VI and integrin α(2) β(1) . Adhesion and degranulation-promoting adapter protein (ADAP) regulates α(IIb) β(3) in platelets and α(L) β(2) in T cells, and is phosphorylated in GPVI-deficient platelets activated by collagen.

OBJECTIVES

To determine whether ADAP plays a role in collagen-induced platelet activation and in the regulation and function of α(2) β(1).

METHODS

Using ADAP(-/-) mice and synthetic collagen peptides, we investigated the role of ADAP in platelet aggregation, adhesion, spreading, thromboxane synthesis, and tyrosine phosphorylation.

RESULTS AND CONCLUSIONS

Platelet aggregation and phosphorylation of phospholipase Cγ2 induced by collagen were attenuated in ADAP(-/-) platelets. However, aggregation and signaling induced by collagen-related peptide (CRP), a GPVI-selective agonist, were largely unaffected. Platelet adhesion to CRP was also unaffected by ADAP deficiency. Adhesion to the α(2) β(1) -selective ligand GFOGER and to a peptide (III-04), which supports adhesion that is dependent on both GPVI and α(2) β(1), was reduced in ADAP(-/-) platelets. An impedance-based label-free detection technique, which measures adhesion and spreading of platelets, indicated that, in the absence of ADAP, spreading on GFOGER was also reduced. This was confirmed with non-fluorescent differential-interference contrast microscopy, which revealed reduced filpodia formation in ADAP(-/-) platelets adherent to GFOGER. This indicates that ADAP plays a role in mediating platelet activation via the collagen-binding integrin α(2) β(1). In addition, we found that ADAP(-/-) mice, which are mildly thrombocytopenic, have enlarged spleens as compared with wild-type animals. This may reflect increased removal of platelets from the circulation.

Anti-inflammatory effects of benfotiamine are mediated through the regulation of the arachidonic acid pathway in macrophages

Benfotiamine, a lipid-soluble analogue of vitamin B1, is a potent antioxidant that is used as a food supplement for the treatment of diabetic complications. Our recent study (U.C. Yadav et al., Free Radic. Biol. Med. 48:1423-1434, 2010) indicates a novel role for benfotiamine in the prevention of bacterial endotoxin, lipopolysaccharide (LPS)-induced cytotoxicity and inflammatory response in murine macrophages. Nevertheless, it remains unclear how benfotiamine mediates anti-inflammatory effects. In this study, we investigated the anti-inflammatory role of benfotiamine in regulating arachidonic acid (AA) pathway-generated inflammatory lipid mediators in RAW264.7 macrophages. Benfotiamine prevented the LPS-induced activation of cPLA2 and release of AA metabolites such as leukotrienes, prostaglandin E2, thromboxane 2 (TXB2), and prostacyclin (PGI2) in macrophages. Further, LPS-induced expression of AA-metabolizing enzymes such as COX-2, LOX-5, TXB synthase, and PGI2 synthase was significantly blocked by benfotiamine. Furthermore, benfotiamine prevented the LPS-induced phosphorylation of ERK1/2 and expression of transcription factors NF-κB and Egr-1. Benfotiamine also prevented the LPS-induced oxidative stress and protein-HNE adduct formation. Most importantly, compared to specific COX-2 and LOX-5 inhibitors, benfotiamine significantly prevented LPS-induced macrophage death and monocyte adhesion to endothelial cells. Thus, our studies indicate that the dual regulation of the COX and LOX pathways in AA metabolism could be a novel mechanism by which benfotiamine exhibits its potential anti-inflammatory response.

Effects of short- and long-term hypercholesterolemia on contrast-induced acute kidney injury

BACKGROUND

Whether hypercholesterolemia is a risk factor for contrast-induced acute kidney injury (CI-AKI) remains unclear. In the present study, the effects of short- and long-term dietary hypercholesterolemia on contrast media-induced nephrotoxicity were evaluated.

METHODS

Rats were fed either a normal rodent diet (N) or high-cholesterol diet (H). At the end of 2 and 8 weeks, 8 rats from each diet group were given a tail vein injection of either iohexol (group NC and group HC) or vehicle (group N and group H). Blood lipids, renal function and renal hemodynamics were evaluated 1 day after contrast media administration. Renal and urinary prostaglandin E(2) (PGE(2)) and thromboxane B(2) (TXB(2)) were detected by radioimmunoassay. Renal nitric oxide and malondialdehyde (MDA) were measured by the Griess reaction and thiobarbituric acid method, respectively.

RESULTS

Contrast media administration increased serum creatinine levels and induced severe renal tubular necrosis in rats fed the high-cholesterol diet for 8 weeks but not in rats fed the normal diet or high-cholesterol diet for 2 weeks. The renal and urinary PGE(2) and TXB(2) levels increased significantly in rats in group H and group HC at the end of 8 weeks. Renal nitric oxide production decreased, and MDA levels increased markedly in group HC and group H at the end of 8 weeks.

CONCLUSIONS

We conclude that long-term hypercholesterolemia appeared to be a risk factor for CI-AKI, which might be associated with disorders in intrarenal prostaglandins and abnormalities in renal nitric oxide system induced by lipid peroxidation.

Aspirin extrusion from human platelets through multidrug resistance protein-4-mediated transport: evidence of a reduced drug action in patients after coronary artery bypass grafting

OBJECTIVES

In this study we investigate: 1) the role of multidrug resistance protein-4 (MRP4), an organic anion unidirectional transporter, in modulating aspirin action on human platelet cyclooxygenase (COX)-1; and 2) whether the impairment of aspirin-COX-1 interaction, found in coronary artery bypass grafting (CABG) patients, could be dependent on MRP4-mediated transport.

BACKGROUND

Platelets of CABG patients present a reduced sensitivity to aspirin despite in vivo and in vitro drug treatment. Aspirin is an organic anion and could be a substrate for MRP4.

METHODS

Intracellular aspirin concentration and drug COX-1 activity, measured by thrombin-induced thromboxane B2 (TxB2) production, were evaluated in platelets obtained from healthy volunteers (HV) and hematopoietic-progenitor cell cultures reducing or not reducing MRP4-mediated transport. Platelet MRP4 expression was evaluated, in platelets from HV and CABG patients, by dot-blot or by immunogold-electromicrographs or immunofluorescence-microscopy analysis.

RESULTS

Inhibition of MRP4-mediated transport by dipyridamole or Mk-571 increases aspirin entrapment and its in vitro effect on COX-1 activity (142.7 ± 34.6 pg/10(8) cells vs. 343.7 ± 169.3 pg/10⁸ cells TxB2-production). Platelets derived from megakaryocytes transfected with MRP4 small interfering ribonucleic acid have a higher aspirin entrapment and drug COX-1 activity. Platelets from CABG patients showed a high expression of MRP4 whose in vitro inhibition enhanced aspirin effect on COX-1 (349 ± 141 pg/10⁸ cells vs. 1,670 ± 646 pg/10⁸ cells TxB2-production).

CONCLUSIONS

Aspirin is a substrate for MRP4 and can be extruded from platelet through its transportation. Aspirin effect on COX-1 is little-related to MRP4-mediated aspirin transport in HV, but in CABG patients with MRP4 over-expression, its pharmacological inhibition enhances aspirin action in an efficient way.

In vivo oxidation, platelet activation and simultaneous occurrence of natural immunity in atherosclerosis-prone mice

BACKGROUND

Several murine models are susceptible to atherosclerosis, such as low density-lipoprotein receptor-deficient (LDLR-/-) and apolipoprotein E-deficient (apoE-/-) mice, and are used for studying pathophysiological mechanisms. Atherosclerotic lesions in the aortic valve and thoracic/abdominal aorta are commonly associated with hyperlipidemia. We recently demonstrated the development of large atherosclerotic plaques in Helicobacter pylori-infected heterozygous LDLR+/- apoE+/- mice.

OBJECTIVES

To measure novel biomarkers related to atherosclerosis, blood coagulation, and oxidative stress in order to investigate their possible pathogenic roles in atherosclerosis-prone mice.

METHODS

Mice were fed with a normal chow diet or high-fat diet and sacrificed at different age intervals to measure aortic plaque size. Plasma cholesterol was enzymatically measured. Enzyme-linked immunosorbent assay was used to measure oxidized LDL (oxLDL)/beta-2-glycoprotein I (beta2GPI) complexes, immunoglobulin M (IgM) antibodies against native LDL, oxLDL, or oxLDL/beta2GPI, and urine 11-dehydro-thromboxane B2 (11-dhTxB2) or 8-hydroxy-deoxyguanosine.

RESULTS

There was a parallel increase in plaque size, plasma cholesterol, and urinary 11-dhTxB2 in atherosclerosis-prone mice. In contrast to atherosclerosis-prone strains, an elevation of urinary 11-dhTxB2 with no significant plaque generation was observed in LDLR+/- 1 apoE+/- mice. The atherogenic autoantigen oxLDL/beta2GPI complex was detected only in LDLRI mice. These levels seem to depend on plaque size. IgM antibodies against oxLDL in apoE-/- mice were found, accompanied by atherosclerotic progression.

CONCLUSIONS

Progression of atherosclerotic lesions was associated not only with hypercholesterolemia but also with platelet activation and natural autoimmune-mediated regulatory mechanism(s) in murine models.