Delayed postprandial TAG peak after intake of SFA compared with PUFA in subjects with and without familial hypercholesterolaemia: a randomised controlled trial.

Postprandial hypertriacylglycerolaemia is associated with an increased risk of developing CVD. How fat quality influences postprandial lipid response is scarcely explored in subjects with familial hypercholesterolaemia (FH). The aim of this study was to investigate the postprandial response of TAG and lipid sub-classes after consumption of high-fat meals with different fat quality in subjects with FH compared with normolipidaemic controls. A randomised controlled double-blind cross-over study with two meals and two groups was performed. A total of thirteen hypercholesterolaemic subjects with FH who discontinued lipid-lowering treatment 4 weeks before and during the study, and fourteen normolipidaemic controls, were included. Subjects were aged 18-30 years and had a BMI of 18·5-30·0 kg/m2. Each meal consisted of a muffin containing 60 g (70 E%) of fat, either mainly SFA (40 E%) or PUFA (40 E%), eaten in a random order with a wash-out period of 3-5 weeks between the meals. Blood samples were collected at baseline (fasting) and 2, 4 and 6 h after intake of the meals. In both FH and control subjects, the level of TAG and the largest VLDL sub-classes peaked at 2 h after intake of PUFA and at 4 h after intake of SFA. No significant differences were found in TAG levels between meals or between groups (0·25≤P≤0·72). The distinct TAG peaks may reflect differences in the postprandial lipid metabolism after intake of fatty acids with different chain lengths and degrees of saturation. The clinical impact of these findings remains to be determined.

Validity of bioelectrical impedance analysis in estimation of fat-free mass in colorectal cancer patients.

BACKGROUND & AIMS: Bioelectrical impedance analysis (BIA) is an accessible and cheap method to measure fat-free mass (FFM). However, BIA estimates are subject to uncertainty in patient populations with altered body composition and hydration. The aim of the current study was to validate a whole-body and a segmental BIA device against dual-energy X-ray absorptiometry (DXA) in colorectal cancer (CRC) patients, and to investigate the ability of different empiric equations for BIA to predict DXA FFM (FFMDXA). METHODS: Forty-three non-metastatic CRC patients (aged 50-80 years) were enrolled in this study. Whole-body and segmental BIA FFM estimates (FFMwhole-bodyBIA, FFMsegmentalBIA) were calculated using 14 empiric equations, including the equations from the manufacturers, before comparison to FFMDXA estimates. RESULTS: Strong linear relationships were observed between FFMBIA and FFMDXA estimates for all equations (R2 = 0.94-0.98 for both devices). However, there were large discrepancies in FFM estimates depending on the equations used with mean differences in the ranges -6.5-6.8 kg and -11.0-3.4 kg for whole-body and segmental BIA, respectively. For whole-body BIA, 77% of BIA derived FFM estimates were significantly different from FFMDXA, whereas for segmental BIA, 85% were significantly different. For whole-body BIA, the Schols* equation gave the highest agreement with FFMDXA with mean difference ±SD of -0.16 ± 1.94 kg (p = 0.582). The manufacturer's equation gave a small overestimation of FFM with 1.46 ± 2.16 kg (p < 0.001) with a tendency towards proportional bias (r = 0.28, p = 0.066). For segmental BIA, the Heitmann* equation gave the highest agreement with FFMDXA (0.17 ± 1.83 kg (p = 0.546)). Using the manufacturer's equation, no difference in FFM estimates was observed (-0.34 ± 2.06 kg (p = 0.292)), however, a clear proportional bias was detected (r = 0.69, p < 0.001). Both devices demonstrated acceptable ability to detect low FFM compared to DXA using the optimal equation. CONCLUSION: In a population of non-metastatic CRC patients, mostly consisting of Caucasian adults and with a wide range of body composition measures, both the whole-body BIA and segmental BIA device provide FFM estimates that are comparable to FFMDXA on a group level when the appropriate equations are applied. At the individual level (i.e. in clinical practice) BIA may be a valuable tool to identify patients with low FFM as part of a malnutrition diagnosis.

N-Acetylcysteine Amide Exerts Possible Neuroprotective Effects in Newborn Pigs after Perinatal Asphyxia.

BACKGROUND: Perinatal asphyxia and ensuing reoxygenation change the antioxidant capacity of cells and organs. OBJECTIVES: To analyze the neuroprotective effect of the antioxidant N-acetylcysteine amide (NACA) after perinatal hypoxia-reoxygenation with an emphasis on proinflammatory cytokines and the transcription factor NF-κB in the prefrontal cortex of neonatal pigs. METHODS: Twenty-nine newborn pigs, aged 12-36 h, were subjected to global hypoxia and hypercapnia. One sham-operated group (n = 5) and 2 experimental groups (n = 12) were exposed to 8% oxygen, until the base excess was -20 mmol/l or the mean arterial blood pressure fell to <20 mm Hg (asphyxia with NACA or saline). The pigs were observed for 9.5 h after hypoxia. Samples of prefrontal cortex and plasma were analyzed. RESULTS: Cortex: there was no significant difference in mRNA expression between the intervention groups regarding IL-1ß, IL6, TNFα, MMP2, MMP9 or IL18. Pigs exposed to hypoxia-reoxygenation and treatment with NACA (NACA-pigs) had a significantly lower protein concentration of IL-1ß than pigs treated with saline (placebo controls), i.e. 8.8 ± 3.9 versus 16.8 ± 10.5 pg/mg protein (p = 0.02). The activation of the transcription factor NF-κB (measured as the fold-change of phosphorylated p65Ser 536), was reduced in the NACA-pigs when compared to the placebo controls (5.2 ± 4.3 vs. 16.0 ± 13.5; p = 0.02). No difference between the intervention groups regarding brain histopathology or in the levels of 8-oxoguanine measured in the prefrontal cortex were observed. Plasma: the NACA-pigs had a stronger reduction of TNFα in the first 30 min following asphyxia compared with the placebo controls, i.e. 36 (30-44) versus 24 (14-32)% (p = 0.01). CONCLUSION: The reduced levels of the pivotal inflammatory markers IL-1ß and TNFα and the transcription factor NF-κB may indicate that NACA has possible neuroprotective effects after perinatal asphyxia.

The NLRP3 inflammasome is up-regulated in cardiac fibroblasts and mediates myocardial ischaemia-reperfusion injury.

AIMS: Nucleotide-binding oligomerization domain-Like Receptor with a Pyrin domain 3 (NLRP3) is considered necessary for initiating a profound sterile inflammatory response. NLRP3 forms multi-protein complexes with Apoptosis-associated Speck-like protein containing a Caspase recruitment domain (ASC) and Caspase-1, which activate pro-interleukin-1ß (IL-1ß) and pro-IL-18. The role of NLRP3 in cardiac cells is not known. Thus, we investigated the expression and function of NLRP3 during myocardial ischaemia. METHODS AND RESULTS: Myocardial infarction (MI) was induced in adult C57BL/6 mice and Wistar rats by ligation of the coronary artery. A marked increase in NLRP3, IL-1ß, and IL-18 mRNA expression was found in the left ventricle after MI, primarily located to myocardial fibroblasts. In vitro studies in cells from adult mice showed that myocardial fibroblasts released IL-1ß and IL-18 when primed with lipopolysaccharide and subsequently exposed to the danger signal adenosine triphosphate, a molecule released after tissue damage during MI. When hearts were isolated from NLRP3-deficient mice, perfused and subjected to global ischaemia and reperfusion, a marked improvement of cardiac function and reduction of hypoxic damage was found compared with wild-type hearts. This was not observed in ASC-deficient hearts, potentially reflecting a protective role of other ASC-dependent inflammasomes or inflammasome-independent effects of NLRP3. CONCLUSION: This study shows that the NLRP3 inflammasome is up-regulated in myocardial fibroblasts post-MI, and may be a significant contributor to infarct size development during ischaemia-reperfusion.

Syndecan-4 signaling via NFAT regulates extracellular matrix production and cardiac myofibroblast differentiation in response to mechanical stress.

Pressure overload activates cardiac fibroblasts leading to excessive production of extracellular matrix which may contribute to compromised heart function. The activated fibroblast acquires smooth muscle-like features such as expression of smooth muscle α-actin (SMA) and SM22 and is therefore referred to as myofibroblast. The molecular mechanisms underlying mechanical stress-induced myofibroblast differentiation are poorly defined. The objective of this study was to examine the potential roles of the transmembrane proteoglycan syndecan-4 and the calcineurin-dependent transcription factor nuclear factor of activated T-cells (NFAT) in myofibroblast differentiation. Aortic banding resulted in elevated collagen I and III, fibronectin, SMA and SM22 mRNA in the left ventricles of wild-type mice, whereas this response was markedly reduced in syndecan-4(-/-) mice. Myofibroblast differentiation in vitro was associated with increased SMA, collagen I and III expression and NFAT-luciferase activity, all of which were reduced in fibroblasts from syndecan-4(-/-) mice or after treatment with calcineurin/NFAT blockers. Following cyclic stretch, NFATc4 was activated in cardiac fibroblasts in a syndecan-4- and calcineurin-dependent manner. Syndecan-4 and calcineurin co-localized and mechanical stress resulted in dephosphorylation of serine179 of syndecan-4, an intracellular residue critical for calcineurin interaction. Over-expression of NFATc4 up-regulated collagen III, MRTF-A (a transcriptional regulator of SMA) and the NFAT-target regulator of calcineurin 1.4 (RCAN1.4). Our data demonstrate that syndecan-4 is important for the differentiation of cardiac fibroblasts into myofibroblasts in the pressure-overloaded heart and that the calcineurin/NFAT pathway is engaged upon mechanical stress in a syndecan-4-dependent manner, playing an active role in myofibroblast differentiation and extracellular matrix production. This article is part of a Special Issue entitled 'Possible Editorial'.

Secretogranin II; a protein increased in the myocardium and circulation in heart failure with cardioprotective properties.

BACKGROUND: Several beneficial effects have been demonstrated for secretogranin II (SgII) in non-cardiac tissue. As cardiac production of chromogranin A and B, two related proteins, is increased in heart failure (HF), we hypothesized that SgII could play a role in cardiovascular pathophysiology. METHODOLOGY/PRINCIPAL FINDINGS: SgII production was characterized in a post-myocardial infarction heart failure (HF) mouse model, functional properties explored in experimental models, and circulating levels measured in mice and patients with stable HF of moderate severity. SgII mRNA levels were 10.5 fold upregulated in the left ventricle (LV) of animals with myocardial infarction and HF (p<0.001 vs. sham-operated animals). SgII protein levels were also increased in the LV, but not in other organs investigated. SgII was produced in several cell types in the myocardium and cardiomyocyte synthesis of SgII was potently induced by transforming growth factor-ß and norepinephrine stimulation in vitro. Processing of SgII to shorter peptides was enhanced in the failing myocardium due to increased levels of the proteases PC1/3 and PC2 and circulating SgII levels were increased in mice with HF. Examining a pathophysiological role of SgII in the initial phase of post-infarction HF, the SgII fragment secretoneurin reduced myocardial ischemia-reperfusion injury and cardiomyocyte apoptosis by 30% and rapidly increased cardiomyocyte Erk1/2 and Stat3 phosphorylation. SgII levels were also higher in patients with stable, chronic HF compared to age- and gender-matched control subjects: median 0.16 (Q1-3 0.14-0.18) vs. 0.12 (0.10-0.14) nmol/L, p<0.001. CONCLUSIONS: We demonstrate increased myocardial SgII production and processing in the LV in animals with myocardial infarction and HF, which could be beneficial as the SgII fragment secretoneurin protects from ischemia-reperfusion injury and cardiomyocyte apoptosis. Circulating SgII levels are also increased in patients with chronic, stable HF and may represent a new cardiac biomarker.

Inhibition of SMAD2 phosphorylation preserves cardiac function during pressure overload.

AIMS: Left ventricular (LV) pressure overload leads to myocardial remodelling and reduced cardiac function. Both cardioprotective and deleterious effects have been attributed to SMAD2/3 (SMAD, small mothers against decapentaplegic) signalling, but the role of these important molecules in pressure overload remains unclear. The aim of this study was to examine the effects of SMAD2 inhibition on cardiac function and remodelling in mice subjected to aortic banding (AB), using a small molecule inhibitor (SM16) of SMAD2 signalling. METHODS AND RESULTS: C57BL/6 mice were subjected to 1 week of AB, which led to a three-fold increased phosphorylation of SMAD2 that was reduced by SM16 (P≤ 0.05), as measured by western blotting. Cardiac function was evaluated by echocardiography and was preserved by SM16, as fractional shortening was increased by 38% (P≤ 0.05) and mitral flow deceleration reduced by 28% compared with AB mice not receiving SM16 (P≤ 0.05). In accordance with this, SM16 abolished the 21% increase in lung weight in AB mice (P≤ 0.05). Cardiomyocyte hypertrophy and foetal gene expression, as measured by qPCR, were also reduced. Myocardial collagen protein was unaltered 1 week after AB. LV sarcoplasmic reticulum Ca(2+)ATPase (SERCA2) reduction in AB mice and in transforming growth factor-ß1-stimulated rat cardiomyocytes was diminished by SM16. Ca(2+) transient decay kinetics were improved in cardiomyocytes isolated from AB mice receiving SM16. CONCLUSION: In pressure overload, pharmacological inhibition of SMAD2 signalling attenuated cardiomyocyte hypertrophy and preserved cardiac function. SM16 prevented SMAD2-mediated downregulation of SERCA2 in vivo and in cardiomyocytes, suggesting improved cardiomyocyte Ca(2+) handling as a possible cardioprotective mechanism.

Syndecan-4 is essential for development of concentric myocardial hypertrophy via stretch-induced activation of the calcineurin-NFAT pathway.

Sustained pressure overload leads to compensatory myocardial hypertrophy and subsequent heart failure, a leading cause of morbidity and mortality. Further unraveling of the cellular processes involved is essential for development of new treatment strategies. We have investigated the hypothesis that the transmembrane Z-disc proteoglycan syndecan-4, a co-receptor for integrins, connecting extracellular matrix proteins to the cytoskeleton, is an important signal transducer in cardiomyocytes during development of concentric myocardial hypertrophy following pressure overload. Echocardiographic, histochemical and cardiomyocyte size measurements showed that syndecan-4(-/-) mice did not develop concentric myocardial hypertrophy as found in wild-type mice, but rather left ventricular dilatation and dysfunction following pressure overload. Protein and gene expression analyses revealed diminished activation of the central, pro-hypertrophic calcineurin-nuclear factor of activated T-cell (NFAT) signaling pathway. Cardiomyocytes from syndecan-4(-/-)-NFAT-luciferase reporter mice subjected to cyclic mechanical stretch, a hypertrophic stimulus, showed minimal activation of NFAT (1.6-fold) compared to 5.8-fold increase in NFAT-luciferase control cardiomyocytes. Accordingly, overexpression of syndecan-4 or introducing a cell-permeable membrane-targeted syndecan-4 polypeptide (gain of function) activated NFATc4 in vitro. Pull-down experiments demonstrated a direct intracellular syndecan-4-calcineurin interaction. This interaction and activation of NFAT were increased by dephosphorylation of serine 179 (pS179) in syndecan-4. During pressure overload, phosphorylation of syndecan-4 was decreased, and association between syndecan-4, calcineurin and its co-activator calmodulin increased. Moreover, calcineurin dephosphorylated pS179, indicating that calcineurin regulates its own binding and activation. Finally, patients with hypertrophic myocardium due to aortic stenosis had increased syndecan-4 levels with decreased pS179 which was associated with increased NFAT activation. In conclusion, our data show that syndecan-4 is essential for compensatory hypertrophy in the pressure overloaded heart. Specifically, syndecan-4 regulates stretch-induced activation of the calcineurin-NFAT pathway in cardiomyocytes. Thus, our data suggest that manipulation of syndecan-4 may provide an option for therapeutic modulation of calcineurin-NFAT signaling.

Revisited and revised: is RhoA always a villain in cardiac pathophysiology?

The neonatal rat ventricular myocyte model of hypertrophy has provided tremendous insight with regard to signaling pathways regulating cardiac growth and gene expression. Many mediators thus discovered have been successfully extrapolated to the in vivo setting, as assessed using genetically engineered mice and physiological interventions. Studies in neonatal rat ventricular myocytes demonstrated a role for the small G-protein RhoA and its downstream effector kinase, Rho-associated coiled-coil containing protein kinase (ROCK), in agonist-mediated hypertrophy. Transgenic expression of RhoA in the heart does not phenocopy this response, however, nor does genetic deletion of ROCK prevent hypertrophy. Pharmacologic inhibition of ROCK has effects most consistent with roles for RhoA signaling in the development of heart failure or responses to ischemic damage. Whether signals elicited downstream of RhoA promote cell death or survival and are deleterious or salutary is, however, context and cell-type dependent. The concepts discussed above are reviewed, and the hypothesis that RhoA might protect cardiomyocytes from ischemia and other insults is presented. Novel RhoA targets including phospholipid regulated and regulating enzymes (Akt, PI kinases, phospholipase C, protein kinases C and D) and serum response element-mediated transcriptional responses are considered as possible pathways through which RhoA could affect cardiomyocyte survival.

Increased production of CXCL16 in experimental and clinical heart failure: a possible role in extracellular matrix remodeling.

BACKGROUND: Inflammation has been implicated in the pathogenesis of heart failure (HF), but knowledge about the production and role of inflammatory actors remains incomplete. On the basis of its role in vascular inflammation, vascular proliferation, and matrix degradation, we hypothesized a role for the chemokine CXCL16 in the pathogenesis of myocardial remodeling and development of HF. METHODS AND RESULTS: Our main findings were (1) patients with chronic HF (n=188) had increased plasma levels of CXCL16, which correlated with disease severity. (2) Left ventricular tissue from patients with end-stage HF (n=8) showed enhanced CXCL16 levels compared with nonfailing left ventricular (n=6) as assessed by Western blotting. (3) In mice with postmyocardial infarction HF, expression of CXCL16, as assessed by real-time RT-PCR, was increased in the infarcted and the noninfarcted areas of left ventricular 3 and 7 days after coronary ligation, indicating early onset of CXCL16 production. Furthermore, mice exposed to aortic banding had enhanced CXCL16 expression in left ventricular, indicating that CXCL16 expression is not related to ischemia alone. (4) In vitro, CXCL16 promoted proliferation and impaired collagen synthesis in myocardial fibroblasts, and in cardiomyocytes and myocardial fibroblasts, CXCL16 increased matrix metalloproteinase activity, primarily reflecting increased matrix metalloproteinase-2 levels. (5) By using specific inhibitors, we showed that the effect of CXCL16 on fibroblasts involved activation of Jun N-terminal kinase. CONCLUSIONS: We show enhanced myocardial CXCL16 expression in experimental and clinical HF. The effect of CXCL16 on cardiomyocytes and fibroblasts suggests a role for CXCL16 in matrix remodeling and ultimately in the development of HF.

Diastolic dysfunction in alveolar hypoxia: a role for interleukin-18-mediated increase in protein phosphatase 2A.

AIMS: Chronic obstructive pulmonary disease with alveolar hypoxia is associated with diastolic dysfunction in the right and left ventricle (LV). LV diastolic dysfunction is not caused by increased afterload, and we recently showed that reduced phosphorylation of phospholamban at serine (Ser) 16 may explain the reduced relaxation of the myocardium. Here, we study the mechanisms leading to the hypoxia-induced reduction in phosphorylation of phospholamban at Ser16. METHODS AND RESULTS: In C57Bl/6j mice exposed to 10% oxygen, signalling molecules were measured in cardiac tissue, sarcoplasmic reticulum (SR)-enriched membrane preparations, and serum. Cardiomyocytes isolated from neonatal mice were exposed to interleukin (IL)-18 for 24 h. The beta-adrenergic pathway in the myocardium was not altered by alveolar hypoxia, as assessed by measurements of beta-adrenergic receptor levels, adenylyl cyclase activity, and subunits of cyclic AMP-dependent protein kinase. However, alveolar hypoxia led to a significantly higher amount (124%) and activity (234%) of protein phosphatase (PP) 2A in SR-enriched membrane preparations from LV compared with control. Serum levels of an array of cytokines were assayed, and a pronounced increase in IL-18 was observed. In isolated cardiomyocytes, treatment with IL-18 increased the amount and activity of PP2A, and reduced phosphorylation of phospholamban at Ser16 to 54% of control. CONCLUSION: Our results indicate that the diastolic dysfunction observed in alveolar hypoxia might be caused by increased circulating IL-18, thereby inducing an increase in PP2A and a reduction in phosphorylation of phospholamban at Ser16.

Dysregulated osteoprotegerin/RANK ligand/RANK axis in clinical and experimental heart failure.

BACKGROUND: Persistent inflammation appears to play a role in the development of heart failure (HF). Osteoprotegerin (OPG), the receptor activator of nuclear factor-kappaB (RANK), and RANK ligand (RANKL) are newly discovered members of the tumor necrosis factor superfamily that are critical regulators in bone metabolism but appear also to be involved in immune responses. We hypothesized that the OPG/RANK/RANKL axis could be involved in the pathogenesis of heart failure (HF), and this hypothesis was investigated in both experimental and clinical studies. METHODS AND RESULTS: Our main and novel findings were as follows: (1) In a rat model of postinfarction HF, we found persistently increased gene expression of OPG, RANK, and RANKL in the ischemic part of the left ventricle (LV) and, for OPG, in the nonischemic part that involved both noncardiomyocyte and in particular cardiomyocyte tissue. (2) Enhanced myocardial protein levels of OPG, RANK, and RANKL, in particular, were also seen in human HF, and using immunohistochemistry, we localized these mediators to cardiomyocytes within the LV in both experimental and clinical HF. (3) In human HF, we also found increased systemic expression of RANKL (T cells and serum) and OPG (serum), with increasing levels according to functional, hemodynamic, and neurohormonal disease severity. (4) RANKL increased total matrix metalloproteinase activity in human fibroblasts, which indicates a matrix-degrading net effect and suggests a potential mechanism by which enhanced RANKL expression in HF may contribute to LV dysfunction. CONCLUSIONS: These findings suggest a potential role for known mediators of bone homeostasis in the pathogenesis of HF and possibly represents new targets for therapeutic intervention in this disorder.

Leukemia inhibitory factor reduces contractile function and induces alterations in energy metabolism in isolated cardiomyocytes.

Interleukin (IL)-6 related cytokines may be involved in the pathophysiology of heart failure. Leukemia inhibitory factor (LIF) is an IL-6 related cytokine, and elevated levels of LIF have been found in failing hearts. The aim of our study was to investigate how LIF may influence isolated cardiomyocytes. Adult cardiomyocytes were isolated from male Wistar rat hearts and treated with 1 nM LIF for 48 h. Contractile function was measured using a video-edge detection system. Fractional shortening was reduced at 0.25 Hz in LIF treated cells (7.4% +/- 0.5%) compared to control cells (9.0% +/- 0.7%). Gene expression analysis showed that expression of the mitochondrial ATP-synthase F(1) alpha subunit was reduced in cells exposed to LIF. The activity of the enzyme was also reduced in these cells (0.10 +/- 0.05 mumol/min per mg protein) compared to controls (1.23 +/- 0.40 mumol/min per mg protein). The levels of ATP and creatine phosphate were reduced by 15.0% +/- 3.0% and 11.2% +/- 2.7% in LIF treated cells. LIF increased both (3)H-deoxyglucose uptake and lactate levels, suggesting an increase in anaerobic energy metabolism. Beta-oxidation of (14)C-oleic acid was increased by 51.2% +/- 14.1% following LIF treatment, but no changes were found in cellular uptake or oxidation of (14)C-oleic acid to CO(2). In conclusion, LIF induces contractile dysfunction and changes in energy metabolism in isolated cardiomyocytes.

Elevated levels of activin A in heart failure: potential role in myocardial remodeling.

BACKGROUND: Although modulation of inflammatory processes has been suggested as a new treatment modality in heart failure (HF), our knowledge about abnormalities in the cytokine network during HF is still limited. On the basis of a previous cDNA array study examining peripheral blood mononuclear cells from HF patients, we hypothesized a role for activin A, a member of the transforming growth factor (TGF)-beta superfamily, in the pathogenesis of HF. METHODS AND RESULTS: This study had 4 main and novel findings. First, serum levels of activin A were significantly elevated in patients with HF (n=86) compared with healthy control subjects (n=20), with increasing levels according to disease severity as assessed by clinical, hemodynamic, and neurohormonal parameters. Second, compared with control subjects, HF patients, as determined by real-time quantitative reverse transcriptase polymer chain reaction, also had markedly increased gene expression of the activin A subunit activin betaA in T cells but not in monocytes. Third, in a rat model of HF, we demonstrated a concerted induction of the gene expression of activin betaA and activin receptors IA, IB, IIA, and IIB after myocardial infarction. Immunohistochemical analysis localized activin A solely to cardiomyocytes. Finally, activin A markedly increased gene expression of mediators involved in infarction healing and myocardial remodeling (ie, atrial natriuretic peptide, brain natriuretic peptide, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, transforming growth factor-beta1, and monocyte chemoattractant protein-1) in neonatal rat cardiomyocytes. CONCLUSIONS: Together with our demonstration of activin A-induced gene expression in neonatal cardiomyocytes of mediators related to myocardial remodeling, the expression pattern of activin A during clinical and experimental HF suggests an involvement of this cytokine in the pathogenesis of HF.

Cardiopulmonary alterations in mRNA expression for interleukin-1beta, the interleukin-6 superfamily and CXC-chemokines during development of postischaemic heart failure in the rat.

Cytokines and chemokines are believed to play a pathogenic role in heart failure (HF). Although some cytokines and chemokines have been examined in HF, information about others is still lacking. We aimed to examine the expression of cytokines belonging to the interleukin (IL)-6 superfamily [IL-6 and ciliary neurotrophic factor (CNTF)], as well as IL-1beta and the CXC-chemokines monocyte chemoattractant protein-1 (MCP-1) and IL-8. We examined their expression in the heart, lung and spleen during development of postischaemic HF 1 and 6 weeks following left coronary artery ligation. Rats, which after myocardial infarction had a left ventricular end-diastolic pressure above 15 mmHg, were considered to be in HF. Sham-operated rats served as controls. A substantial upregulation of cardiac IL-1beta was measured in HF at 1 week, whereas a downregulation was measured in the lungs. At 6 weeks no altered regulation was seen. CNTF was only upregulated in the viable left ventricle at 6 weeks and IL-6 was upregulated in the infarcted region at 1 week. Cardiac MCP-1 was upregulated in the viable and the infarcted region of the failing left ventricle at 1 week, with the highest expression in the latter. In the lung, another pattern of regulation was seen with a significant increase in pulmonary MCP-1 at 6 weeks. IL-8 was only detected in the infarcted region at 1 week. In the spleen, no regulation of cytokines was found. In conclusion, we report an organ-specific regulation of cytokines and chemokines in postischaemic HF. Our novel findings of increased cardiac CNTF and cardiopulmonary MCP-1 mRNA indicate a role for these factors in the pathogenesis of HF.

Increased cardiac IL-18 mRNA, pro-IL-18 and plasma IL-18 after myocardial infarction in the mouse; a potential role in cardiac dysfunction.

OBJECTIVE: Interleukin (IL)-18 has been reported to be an important predictor for mortality in ischemic heart disease. IL-18 has proinflammatory properties, induces cell death and stimulates nitric oxide production. We hypothesized that following myocardial infarction (MI) an increased myocardial IL-18 production occurs, which may be involved in the pathogenesis of post-ischemic heart failure. METHODS AND RESULTS: Seven days after induction of MI in the mouse, myocardial hypertrophy and pulmonary edema were observed. RNase protection assay of tissue from the non-infarcted left ventricular myocardium revealed an increase in IL-18 (2.0-fold; P<0.001) and IL-1 beta (1.6-fold; P<0.001) mRNA after MI. Enhanced abundance of pro-IL-18 (1.4-fold; P<0.05), IL-18 receptor (3.5-fold; P<0.05) and IL-18 binding proteins (1.6-fold; P<0.05) was also demonstrated, whereas cardiac IL-18 protein decreased by 25% (P<0.05) following MI. However, the concentration of circulating IL-18 was significantly elevated (MI; 90.4+/-11.7 pg/ml, sham; 47.2+/-4.2 pg/ml; P<0.001). After MI, enhanced cardiac activity of the pro-IL-18 processing enzyme, caspase-1, was measured. Additionally, a 3.4-fold increase (P<0.001) in the activity of the IL-18 degrading enzyme, caspase-3, was found in cardiac tissue, which may explain the observed reduction of cardiac IL-18 protein abundance. Finally, IL-18 reduced shortening of electrically stimulated adult cardiomyocytes and left ventricular contractility in vivo. CONCLUSIONS: After MI in the mouse, increased production of cardiac IL-18 mRNA and pro-IL-18, as well as circulating IL-18 occurs. Since IL-18 also reduced myocardial contractility, we suggest that IL-18 may be involved in the pathogenesis of contractile dysfunction following MI.