Decrease in serum adiponectin levels in response to treatment predicts good prognosis in acute decompensated heart failure.

Adiponectin is a cardioprotective adipocytokine. Serum adiponectin concentration decreases in patients who are obese but increases in patients with chronic heart failure (CHF). The aim of this study was to explore the temporal changes in serum adiponectin concentration following treatment for acute decompensated heart failure (ADHF). Serum adiponectin was measured on admission and at discharge in 95 patients who were admitted to our hospital with ADHF. Ten patients without heart failure (HF) served as controls. Serum adiponectin concentration was higher on admission in HF patients than in the controls (22.6±13.3 µg/mL vs 9.3±3.9 µg/mL, P<.01). Serum adiponectin concentration decreased after treatment in HF patients (18.0±11.7 µg/mL vs 22.6±13.3 µg/mL, P<.01). The larger temporal decrease in adiponectin level in ADHF was associated with the lower incidence of cardiac death or HF hospitalizations (log-rank, P<.05). Serum adiponectin concentration was elevated in ADHF and decreased following the treatment. How much serum adiponectin decreases in response to treatment in ADHF is an important determinant of the prognosis.

Hyperglycemia induced cell growth and gene expression via the serum response element through RhoA and Rho-kinase in vascular smooth muscle cells.

The impressive correlation between cardiovascular disease and alterations in glucose metabolism has raised the likelihood that atherosclerosis, heart failure, and type 2 diabetes may share common antecedents. Postprandial hyperglycemia has been shown to play an important role on the onset and development of heart failure and cerebral infarction in several large-scale clinical trials. Recently, chronic hyperglycemia has been reported to enhance the vasoconstrictor response by Rho-kinase. We have previously reported that phenylephrine enhanced the vasoconstrictor response in a spontaneous diabetes mellitus OLETF (Otsuka-Long-Evane-Tokushima fatty) rat model. However, the mechanism of hyperglycemia in these reactions, particularly the influence of hyperglycemia on the signal transduction pathway, is still not well understood. We, therefore, examined the effect of hyperglycemia on the cell growth and gene expression of rat aortic smooth-muscle cells (RASMCs). Hyperglycemia accelerated the growth of RASMCs in a concentration-dependent manner. Furthermore, the c-fos gene expression was also increased by hyperglycemia. Phenylephrine activated the c-fos gene expression. Hyperglycemia augmented the phenylephrine-induced c-fos gene expression synergistically in a dose dependent manner. The deletion analysis revealed that the c-fos serum response element (SRE) accounts for the c-fos gene expression. RhoA, and Rho-kinase were involved in hyperglycemia-induced c-fos gene expression. An HMG-CoA reductase inhibitor, Pitavastatin, inhibited these hyperglycemia-augmented reactions by inhibiting RhoA. Hyperglycemia itself increased the cell growth and gene expression. Furthermore, it modifies and augments the cell growth and gene expression by alpha1-AR-mediated stimulation. Statin might therefore be effective for the treatment of hyperglycemia-induced cardiovascular dysfunction.

OCT assessment of thin-cap fibroatheroma distribution in native coronary arteries.

OBJECTIVES: We evaluated the geographic distribution of thin-cap fibroatheromas (TCFAs) in the coronary arteries using optical coherence tomography (OCT), a high-resolution imaging modality. BACKGROUND: Plaque rupture is the most frequent cause of acute myocardial infarction (AMI). It has been recognized that TCFA is the primary plaque type at the site of plaque rupture. METHODS: We performed 3-vessel OCT examinations in 55 patients: 35 AMI and 20 stable angina pectoris patients. The criteria for TCFA in an OCT image was a lipid-rich plaque with fibrotic cap thickness <65 microm. The distance between each TCFA location and the respective coronary artery ostium was measured with motorized OCT imaging pullback. The total length of all 3 coronary arteries imaged by OCT pullbacks was 82 +/- 21 mm in the left anterior descending coronary artery (LAD), 67 +/- 26 mm in the left circumflex coronary artery (LCx), and 104 +/- 32 mm in the right coronary artery (RCA). RESULTS: OCT detected 94 TCFAs in 165 coronary arteries. The minimum fibrous-cap thickness of TCFAs was 57.4 +/- 5.4 microm in AMI patients, and 55.9 +/- 7.3 microm in stable angina pectoris patients (p = 0.4). Of the total of 94 TCFAs, 28 were detected in the LAD, 18 in the LCx, and 48 in the RCA. Most LAD TCFAs were located between 0 and 30 mm from the LAD ostium (76%). Conversely, LCx and RCA TCFAs were evenly distributed throughout the entire coronary length. The clustering of the TCFAs was similar in culprit segments as compared with nonculprit segments. In AMI patients, most LAD TCFAs were distributed near side branches, mainly positioned opposite the side branch bifurcation. CONCLUSIONS: Three-vessel OCT imaging showed that TCFAs tend to cluster in predictable spots within the proximal segment of the LAD, but develop relatively evenly in the LCx and RCA arteries.

Serum interleukin-6 and C-reactive protein are markedly elevated in acute decompensated heart failure patients with left ventricular systolic dysfunction.

Cytokines play important roles in heart failure (HF). We examined whether cytokine levels are different in acute decompensated heart failure (ADHF) patients between with left ventricular systolic dysfunction (LVSDF) and with preserved LV ejection function (PLVEF). We studied 81 HF patients who were admitted to our hospital with acute decompensation. They were divided into two groups: LVSDF (LVEF)<45% and PLVEF (LVEF45%). Serum interleukin-6 (IL-6), highly sensitive C-reactive protein (hsCRP), tumor necrosis factor alpha (TNF-alpha), and IL-18 and plasma brain natriuretic peptide (BNP) were measured on admission and at discharge. On admission, IL-6 and hsCRP were higher in LVSDF than in PLVEF. IL-6 and hsCRP decreased after treatment in LVSDF, but not in PLVEF, while plasma BNP levels decreased in both HF with treatment. There was no difference in TNF-alpha or in IL-18 level between LVSDF and PLVEF, and they did not change after treatment in either group. In conclusion, cytokine profiles were different in ADHF between those with LVSDF and PLVEF. Activation of IL-6-hsCRP pathway may play a specific role in ADHF with LVSDF.

Iron regulatory hormone hepcidin decreases in chronic heart failure patients with anemia.

BACKGROUND: The etiology of anemia is still unclear in patients with chronic heart failure (CHF). Hepcidin is an iron regulatory peptide that is synthesized in the liver to suppress iron absorption and utilization. Hepcidin synthesis is suppressed by anemia, hypoxia and erythropoiesis, and induced by inflammation. Inflammatory cytokines, such as interleukin-6 (IL-6), increase the synthesis of hepcidin, resulting in anemia of inflammation (AI). The serum hepcidin concentration in CHF patients with anemia was measured in order to better understand anemia in CHF. METHODS AND RESULTS: Serum hepcidin-25, erythropoietin (EPO), ferritin and IL-6 concentrations were measured in 61 CHF patients. Among these patients, 36 patients had anemia. A group of 16 patients without cardiac disease or anemia were recruited as controls. Serum IL-6 and EPO were higher and hepcidin-25 was lower in CHF patients with anemia than in controls. Hepcidin-25 correlated with EPO and ferritin but not with IL-6. Results of multivariable regression analysis showed that independent predictors of serum hepcidin-25 included EPO and ferritin but not IL-6. CONCLUSIONS: Serum hepcidin-25 concentrations were regulated by iron storage and erythropoiesis but not by IL-6 in CHF patients with anemia. These findings might indicate that AI is a minor cause of anemia in CHF.

The mechanism of distinct diurnal variations of renin-angiotensin system in aorta and heart of spontaneously hypertensive rats.

Diurnal variations in plasminogen activator inhibitor-1 mRNA expression are different between the spontaneously hypertensive rats (SHRs) and the Wistar-Kyoto (WKY) rats, and between the aorta and the heart. To elucidate the mechanisms, we examined diurnal changes in the circulating renin-angiotensin system in the SHR and WKY rats. Diurnal variations in plasma renin activity (PRA), plasma angiotensin I, and aldosterone concentrations were similar between the SHR and WKY rats. On the other hand, plasma angiotensin II (Ang II) concentration in the SHR was lower than that in the WKY rats at most time points, but increased to the level of the WKY rats in the late light phase. Treatment with AT1 receptor antagonist candesartan increased plasma Ang II concentration except at ZT 8 and lessened its diurnal variation in the SHR. At the peak in plasma Ang II in the SHR, Ang II regulated genes such as transforming growth factor-beta1 and p22phox were upregulated in the aorta. On the other hand, these genes were upregulated throughout the day in the heart of SHR. Candesartan treatment increased AT1a receptor mRNA expression in the heart but not in the aorta of SHR. These findings suggest that an AT1 receptor-mediated mechanism might cause a surge in plasma Ang II concentration at the late light phase in the SHR. Homologous down-regulation of AT1a receptor by Ang II may dampen the effect of a surge in plasma Ang II concentration in the heart of SHR.

Deficiency of nectin-2 leads to cardiac fibrosis and dysfunction under chronic pressure overload.

The intercalated disc, a cell-cell contact site between neighboring cardiac myocytes, plays an important role in maintaining the homeostasis of the heart by transmitting electric and mechanical signals. Changes in the architecture of the intercalated disc have been observed in dilated cardiomyopathy. Among cell-cell junctions in the intercalated disc, adherens junctions are involved in anchoring myofibrils and transmitting force. Nectins are Ca(2+)-independent, immunoglobulin-like cell-cell adhesion molecules that exist in adherens junctions. However, the role of nectins in cardiac homeostasis and integrity of the intercalated disc are unknown. Among the isoforms of nectins, nectin-2 and -4 were expressed at the intercalated disc in the heart. Nectin-2-knockout mice showed normal cardiac structure and function under physiological conditions. Four weeks after banding of the ascending aorta, cardiac function was significantly impaired in nectin-2-knockout mice compared with wild-type mice, although both nectin-2-knockout and wild-type mice developed similar degrees of cardiac hypertrophy. Banded nectin-2-knockout mice displayed cardiac fibrosis more evidently than banded wild-type mice. The disruption of the intercalated discs and disorganized myofibrils were observed in banded nectin-2-knockout mice. Furthermore, the number of apoptotic cardiac myocytes was increased in banded nectin-2-knockout mice. In the hearts of banded nectin-2-knockout mice, Akt remained at lower phosphorylation levels until 2 weeks after banding, whereas c-Jun N-terminal kinase and p38 mitogen-activated protein kinase were highly phosphorylated compared with those of wild-type mice. These results indicate that nectin-2 is required to maintain structure and function of the intercalated disc and protects the heart from pressure-overload-induced cardiac dysfunction.

High salt intake elevated blood pressure but not changed circadian blood pressure rhythm in Otsuka Long-Evans Tokushima Fatty (OLETF) rat.

We examined the effect of high salt intake on mean arterial pressure and circadian blood pressure rhythm in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type II diabetes mellitus. Mean arterial pressure, fasting blood glucose, and fasting plasma insulin in OLETF rats were higher than those in LETO rats, their normoglycemic controls. The amplitude of circadian blood pressure rhythm in LETO rats was smaller than that in OLETF rats. High salt intake elevated blood pressure and exacerbated hyperinsulinemia, but did not change the circadian blood pressure rhythm in OLETF rats.

Adaptive response of the heart to long-term anemia induced by iron deficiency.

Anemia is common in patients with chronic heart failure and an independent predictor of poor prognosis. Chronic anemia leads to left ventricular (LV) hypertrophy and heart failure, but its molecular mechanisms remain largely unknown. We investigated the mechanisms, including the molecular signaling pathway, of cardiac remodeling induced by iron deficiency anemia (IDA). Weanling Sprague-Dawley rats were fed an iron-deficient diet for 20 wk to induce IDA, and the molecular mechanisms of cardiac remodeling were evaluated. The iron-deficient diet initially induced severe anemia, which resulted in LV hypertrophy and dilation with preserved systolic function associated with increased serum erythropoietin (Epo) concentration. Cardiac STAT3 phosphorylation and VEGF gene expression increased by 12 wk of IDA, causing angiogenesis in the heart. Thereafter, sustained IDA induced upregulation of cardiac hypoxia inducible factor-1alpha gene expression and maintained upregulation of cardiac VEGF gene expression and cardiac angiogenesis; however, sustained IDA promoted cardiac fibrosis and lung congestion, with decreased serum Epo concentration and cardiac STAT3 phosphorylation after 20 wk of IDA compared with 12 wk. Upregulation of serum Epo concentration and cardiac STAT3 phosphorylation is associated with a beneficial adaptive mechanism of anemia-induced cardiac hypertrophy, and later decreased levels of these molecules may be critical for the transition from adaptive cardiac hypertrophy to cardiac dysfunction in long-term anemia. Understanding the mechanism of cardiac maladaptation to anemia may lead to a new strategy for treatment of chronic heart failure with anemia.

Aldosterone induces interleukin-18 through endothelin-1, angiotensin II, Rho/Rho-kinase, and PPARs in cardiomyocytes.

Aldosterone (Aldo) is recognized as an important risk factor for cardiovascular diseases. IL-18 induces myocardial hypertrophy, loss of contractility of cardiomyocytes, and apoptosis leading myocardial dysfunction. However, so far, there have been few reports concerning the interaction between Aldo and IL-18. The present study examined the effects and mechanisms of Aldo on IL-18 expression and the roles of peroxisome proliferator-activated receptor (PPAR) agonists in rat cardiomyocytes. We used cultured rat neonatal cardiomyocytes stimulated with Aldo to measure IL-18 mRNA and protein expression, Rho-kinase, and NF-kappaB activity. We also investigated the effects of PPAR agonists on these actions. Aldo, endothelin-1 (ET-1), and angiotensin II (ANG II) increased IL-18 mRNA and protein expression. Mineralocorticoid receptor antagonists, endothelin A receptor antagonist, and ANG II receptor antagonist inhibited Aldo-induced IL-18 expression. Aldo induced ET-1 and ANG II production in cultured media. Moreover, Rho/Rho-kinase inhibitor and statin inhibited Aldo-induced IL-18 expression. On the other hand, Aldo upregulated the activities of Rho-kinase and NF-kappaB. PPAR agonists attenuated the Aldo-induced IL-18 expression and NF-kappaB activity but not the Rho-kinase activity. Our findings indicate that Aldo induces IL-18 expression through a mechanism that involves, at a minimum, ET-1 and ANG II acting via the Rho/Rho-kinase and PPAR/NF-kappaB pathway. The induction of IL-18 in cardiomyocytes by Aldo, ET-1, and ANG II might, therefore, cause a deterioration of the cardiac function in an autocrine and paracrine fashion. The inhibition of the IL-18 expression by PPAR agonists might be one of the mechanisms whereby the beneficial cardiovascular effects are exerted.

Mechanical stretch induced interleukin-18 (IL-18) expression through Angiotensin subtype 1 receptor (AT1R) and endothelin-1 in cardiomyocytes.

Interleukin-18 (IL-18) is a proinflammatory cytokine with multiple biological functions. We and others have demonstrated that an increased level of circulating IL-18 is one of the risk factors for cardiovascular diseases. Endothelin-1 (ET-1) has been reported to be a potent hypertrophy-promoting factor through RhoA and Rho-Kinase. Mechanical stretch induces a hypertrophic response, partly through the production of ET-1 through Endothelin A receptor (ETAR). Moreover, it has also been reported that mechanical stretch induces cardiac hypertrophy through Angiotensin subtype 1 receptor (AT1R). However, the mechanism by which the IL-18 gene expression is regulated in cardiomyocytes has not yet been fully understood. This study was designed to elucidate the functional significance of IL-18 gene expression in response to mechanical stretch. Neonatal rat cardiomyocytes cultured on silicone dishes were subjected to stretch. The moderate 20% mechanical stretch resulted in the elevation of IL-18 expression in a time-dependent manner with the maximal level achieved 36 hours after the stretch. Olmesartan, AT1R antagonist inhibited stretch-induced IL-18 expression. ETAR blockade BQ123 inhibited stretch-induced IL-18 expression. However, the Endothelin B receptor (ETBR) receptor blockade BQ788 did not inhibit this reaction. ET-1 induced IL-18 expression, with a peak induction after 4 hours of incubation. These results might suggest that stretch stimulation of cardiomyocytes induced ET-1 and, subsequently, ET-1 up-regulated the IL-18 expression. Furthermore, Fasudil, a Rho-Kinase inhibitor, and Simvastatin, a HMG-CoA reductase inhibitor, led to a significant reduction in mechanical stretch-induced IL-18 expression. These results indicated, for the first time, that IL-18 expression is induced by mechanical stretch in cardiomyocytes via the ETAR, AT1R, and the Rho/Rho-K pathways. The induction of IL-18 from cardiomyocytes by mechanical stress might cause the deterioration of cardiac functions in autocrine and paracrine fashion. The inhibition of IL-18 expression induced by mechanical stress might be one of the mechanisms that account for the beneficial cardiovascular effects of AT1R antagonist, ETAR blockade, Statin, and Rho-Kinase inhibitor.

Loop diuretic precipitated beriberi in a patient after pancreaticoduodenectomy: a case report.

Upper gastrointestinal tract surgery and diuretic use are 2 unrecognized causes of thiamine (vitamin B1) deficiency. Upper gastrointestinal tract surgery decreases the thiamine absorption, and diuretic use increases urinary excretion of thiamine. We present a case of a patient with a history of pancreaticoduodenectomy who had development of beriberi by diuretic use. A 68-year-old man was referred to our hospital because of pretibial pitting edema, foot numbness, and gait disturbance. He had a history of pancreaticoduodenectomy 8 years before and had been taking loop diuretics for 2 months. He had signs of polyneuropathy and hyperkinetic heart. Beriberi was suspected, and thiamine supplementation was started immediately. Edema disappeared within several days, and signs of polyneuropathy gradually subsided. Because diuretics enhance urinary thiamine excretion, practitioners should use caution for thiamine deficiency when they prescribe diuretics for patients who have a history of upper gastrointestinal surgery and potentially have latent thiamine deficiency.

Two giant renal aneurysms and renal arteriovenous fistula associated with cardiac insufficiency and a sustained elevation of atrial natriuretic peptide and brain natriuretic peptide.

A 64-year-old man presented with chief complaints of exertional dyspnea and palpitation. He had previously undergone left nephrolithotomies twice. A chest roentgenogram showed pleural effusion on both sides with cardiac dilation, and electrocardiography showed a frequent occurrence of ventricular premature contractions. An echocardiogram showed diffuse hypokinesis of the left ventricular wall motion (ejection fraction, 45%) and dilation of the left ventricle (left ventricular end-diastolic dimension, 61 mm). We administered diuretics, ACE inhibitors and a beta-adrenergic blocking agent after making a diagnosis of cardiac insufficiency. Because coronary angiography showed 90% stenosis of the left anterior descending coronary artery (No. 7), we performed coronary angioplasty in this locus. Though both the left ventricular wall motion and ejection fraction improved, and the clinical symptoms disappeared, the left ventricular end-diastolic dimension, and arrhythmia did not improve. Furthermore, the brain natriuretic peptide increased despite these treatments. Thereafter, a left renal artery aneurysm (extrarenal aneurysm measuring 5 cm in diameter and an intrarenal aneurysm measuring 3 cm in diameter) and a left renal arteriovenous fistula were discovered when abdominal echography was performed because of epigastric discomfort. As a result, a left total nephrectomy was performed. Subsequently, the left ventricular end-diastolic dimension and arrhythmia improved, and the brain natriuretic peptide returned to a normal value. We herein report a case that developed cardiac insufficiency due to a renal aneurysm and renal arteriovenous fistula after undergoing left nephrolithotomies twice.

Ultrasound enhances retrovirus-mediated gene transfer.

Viral vector systems are efficient for transfection of foreign genes into many tissues. Especially, retrovirus based vectors integrate the transgene into the genome of the target cells, which can sustain long term expression. However, it has been demonstrated that the transduction efficiency using retrovirus is relatively lower than those of other viruses. Ultrasound was recently reported to increase gene expression using plasmid DNA, with or without, a delivery vehicle. However, there are no reports, which show an ultrasound effect to retrovirus-mediated gene transfer efficiency. Retrovirus-mediated gene transfer systems were used for transfection of 293T cells, bovine aortic endothelial cells (BAECs), rat aortic smooth muscle cells (RASMCs), and rat skeletal muscle myoblasts (L6 cells) with beta-galactosidase (beta-Gal) genes. Transduction efficiency and cell viability assay were performed on 293T cells that were exposed to varying durations (5 to 30 seconds) and power levels (1.0 watts/cm(2) to 4.0 watts/cm(2)) of ultrasound after being transduced by a retrovirus. Effects of ultrasound to the retrovirus itself was evaluated by transduction efficiency of 293T cells. After exposure to varying power levels of ultrasound to a retrovirus for 5 seconds, 293T cells were transduced by a retrovirus, and transduction efficiency was evaluated. Below 1.0 watts/cm(2) and 5 seconds exposure, ultrasound showed increased transduction efficiency and no cytotoxicity to 293T cells transduced by a retrovirus. Also, ultrasound showed no toxicity to the virus itself at the same condition. Exposure of 5 seconds at the power of 1.0 watts/cm(2) of an ultrasound resulted in significant increases in retrovirus-mediated gene expression in all four cell types tested in this experiment. Transduction efficiencies by ultrasound were enhanced 6.6-fold, 4.8-fold, 2.3-fold, and 3.2-fold in 293T cells, BAECs, RASMCs, and L6 cells, respectively. Furthermore, beta-Gal activities were also increased by the retrovirus with ultrasound exposure in these cells. Adjunctive ultrasound exposure was associated with enhanced retrovirus-mediated transgene expression in vitro. Ultrasound associated local gene therapy has potential for not only plasmid-DNA-, but also retrovirus-mediated gene transfer.

Lentiviral vector-mediated gene transfer to endotherial cells compared with adenoviral and retroviral vectors.

Human immunodeficiency virus (HIV, lentivirus) vector has attractive features for gene therapy, including the ability to transduce non-dividing cells and long-term transgene expression. We have already reported that lentivirus vector can transduce well-differentiated rat cardiac myocytes. Endothelial cells (EC) are an attractive target for gene therapy, both for the treatment of cardiovascular disease and for the systemic delivery of recombinant gene products directly into the circulation. There are several reports regarding application of adenovirus and retrovirus based vectors to EC. However, there have been few reports which show the effect to lentivirus-mediated gene transfer efficiency, compared with adenovirus and retrovirus. In this study, bovine aortic endothelial cells (BAECs) were infected, in vitro, with these virus vectors. Transduction efficiency (TE) of beta-Gal gene transfer in BAECs by adenovirus, lentivirus, or retrovirus at MOI10 (Multiplicity of infection) (determined on Hela cells) is 69+/-11, 33+/-8, or 22+/-6% respectively. In adenovirus and lentivirus, almost 100% of BAECs were transduced at MOI 50. However, in retrovirus, TE showed only 48+/-6% at MOI 50 and no increase at MOI 100. The percentage of beta-Gal positive cells was decreased rapidly at longer passage of cells after being transduced by adenovirus. However, lentivirus and retrovirus showed sustained higher percentage of positive cells. Furthermore, transduction by lentiviral vectors had no significant effect on viability of BAECs. Our results indicate that lentivirus showed high-level and long term gene expression in BAECs. Lentivirus can be an effective vector for the ex vivo, genetically modified EC implantation and in vivo gene therapy.

Calcium phosphate coprecipitation greatly enhances transduction of cardiac myocytes and vascular smooth muscle cells by lentivirus vectors.

BACKGROUND: Lentivirus vectors provide a delivery system that can both transduce nondividing cells and integrate transgenes into the genome of target cells without cytotoxicity. However, their relatively low transduction efficiency presents a significant obstacle to progress. OBJECTIVES: In the present paper, a simple and easy method using calcium phosphate (CaPi) to enhance the efficiency of lentivirus gene transfer in both vascular smooth muscle cells and cardiac myocytes is reported. METHODS AND RESULTS: Delivery of lentivirus vectors in the presence of CaPi coprecipitates increased vector-encoded transgene expression up to 13-fold. Of interest, the magnitudes of enhancement of transgene expression by CaPi coprecipitates in 293T cells, vascular smooth muscle cells and cardiac myocytes were greater during brief periods (10 min and 120 min) of virus-cell contact than during long periods (16 h). Moreover, with a short duration of incubation with CaPi coprecipitates (up to 120 min), there was little evidence of direct cell toxicity. CaPi coprecipitates had no effect on host range specificity of ecotropic viruses and thus appears to enhance transduction efficiency physiologically by facilitating physical interaction between virus and cell. CONCLUSIONS: These data show that lentivirus with CaPi coprecipitates increases both the efficiency and the speed of gene transfer. These approaches provide an efficient method and an improved tool for research and possibly for therapy of cardiovascular diseases.

Chylomicron remnants stimulate release of interleukin-1beta by THP-1 cells.

Recent findings suggest that the oxidative modification of low-density lipoproteins (LDL) and an increase in triglyceride-rich lipoprotein particles including chylomicron remnants contribute to the progression of atherosclerosis, as does the inflammatory response. We therefore examined whether and how these lipoproteins affected interleukin (IL)-1beta release and mRNA expression for IL-1beta and IL-18 in THP-1 cells, a human monocyte cell line. Chylomicron remnants increased IL-1beta release into the conditioned medium by THP-1 in a dose- and time-dependent manner. At concentrations up to 1 microg/ml, chylomicron remnants increased IL-1beta release by 4-fold compared with the control. Neither native LDL nor oxidized LDL (OxLDL) significantly increased IL-1beta release. Chylomicron remnants increased IL-1beta mRNA expression by 3 times. Native LDL or OxLDL did not increase IL-1beta mRNA, while neither these lipoproteins nor chylomicron remnants increased IL-18 mRNA. Chylomicron remnants also increased the activities of caspase-1 and nuclear factor (NF)-kappaB significantly, while native LDL or OxLDL did not. In conclusion, chylomicron remnants stimulated IL-1beta mRNA expression and IL-1beta protein production probably via caspase-1 and NF-kappaB activation in THP-1 cells.

Circadian expression of plasminogen activator inhibitor-1 in angiotensin II type 1a receptor knockout mice.

Both the peripheral biological clock and the renin-angiotensin system regulate mRNA expression of plasminogen activator inhibitor-1 (PAI-1). Our objective was to determine whether angiotensin II (Ang II) type 1 (AT1) receptor-mediated signaling contributes to the development of circadian expression of PAI-1 and clock genes in the heart, aorta, liver, and kidney. We sacrificed AT1a receptor knockout (AT1a-KO) and wild-type (WT) 12 week-old mice every 4 hr. We examined mRNA expression for PAI-1 and clock genes (Per2, Bmal1, and Clock) in heart, aorta, liver, and kidney by using the quantitative reverse transcription-polymerase chain reaction. PAI-1 mRNA showed circadian oscillation with a peak occurring during the light phase in the heart, liver, aorta, and kidney of WT mice. Peak expression of PAI-1 in the liver and aorta was decreased in AT1a-KO mice. On the other hand, cardiac PAI-1 expression in AT1a-KO mice was reduced in the dark phase, during which time its expression level was low. There were no significant differences between WT and AT1a-KO mice in renal PAI-1 expression. Clock genes oscillated synchronously in WT and AT1a-KO mice, and there were no significant differences between the WT and the AT1a-KO mice in their expression. Plasma angiotensin II showed little oscillation in the WT mice. We conclude that AT1a receptor-mediated Ang II signaling modulates the circadian expression of PAI-1 in an organ-specific manner. The effect of the renin-angiotensin system on PAI-1 expression appears to be independent of peripheral clock gene expression.