Effects of cardiotrophin-1 on haemodynamics and cardiac function in conscious rats

Potential clinical biomarkers and perspectives in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious cardiovascular complication and the leading cause of death in diabetic patients. Patients typically do not experience any symptoms and have normal systolic and diastolic cardiac functions in the early stages of DCM. Because the majority of cardiac tissue has already been destroyed by the time DCM is detected, research must be conducted on biomarkers for early DCM, early diagnosis of DCM patients, and early symptomatic management to minimize mortality rates among DCM patients. Most of the existing implemented clinical markers are not very specific for DCM, especially in the early stages of DCM. Recent studies have shown that a number of new novel markers, such as galactin-3 (Gal-3), adiponectin (APN), and irisin, have significant changes in the clinical course of the various stages of DCM, suggesting that we may have a positive effect on the identification of DCM. As a summary of the current state of knowledge regarding DCM biomarkers, this review aims to inspire new ideas for identifying clinical markers and related pathophysiologic mechanisms that could be used in the early diagnosis and treatment of DCM.

Cardiotrophin-1 Regulates Adipokine Production in 3T3-L1 Adipocytes and Adipose Tissue From Obese Mice

Cardiotrophin-1 (CT-1) belongs to the IL-6 family of cytokines. Previous studies of our group revealed that CT-1 is a key regulator of glucose and lipid metabolism. The aim of the present study was to analyze the in vitro and in vivo effects of CT-1 on the production of several adipokines involved in body weight regulation, nutrient metabolism, and inflammation. For this purpose, 3T3-L1 adipocytes were incubated with recombinant protein CT-1 (rCT-1) (1-40 ng/ml) for 1 and 18 h. Moreover, the acute effects of rCT-1 administration (0.2 mg/kg, i.v.) for 30 min and 3 h on adipokines levels were also evaluated in high-fat fed obese mice. In 3T3-L1 adipocytes, rCT-1 treatment downregulated the expression and secretion of leptin, resistin, and visfatin. However, rCT-1 significantly stimulated apelin mRNA and secretion. rCT-1 (18 h) also promoted the activation by phosphorylation of AKT, ERK 1/2, and STAT3. Interestingly, pre-treatment with the PI3K inhibitor LY294002 reversed the stimulatory effects of rCT-1 on apelin expression, suggesting that this pathway could be mediating the effects of rCT-1 on apelin production. In contrast, acute administration of rCT-1 (30 min and 3 h) to diet-induced obese mice downregulated leptin and resistin, without significantly modifying apelin or visfatin mRNA in adipose tissue. Furthermore, CT-1 null mice exhibited altered expression of adipokines in adipose tissue. The present study demonstrates that rCT-1 modulates the production of adipokines in vitro and in vivo, suggesting that the regulation of the secretory function of adipocytes could be involved in the metabolic actions of this cytokine. J. Cell. Physiol. 232: 2469-2477, 2017. © 2016 Wiley Periodicals, Inc.

Stimulation of cardiomyogenesis from mouse embryonic stem cells by nuclear translocation of cardiotrophin-1

BACKGROUND

Cardiotrophin-1 (CT-1) controls cardiomyogenesis of mouse embryonic stem (ES) cells.

OBJECTIVES

To investigate the signaling pathway underlying the action of CT-1 on cardiac cell differentiation.

METHODS

Protein expression was analyzed by western blot technique and cardiac areas by immunohistochemistry. Calcium, reactive oxygen species (ROS) and nitric oxide (NO) were assessed by microfluorometry using fluo-4, H2DCF, and DAF-2DA, respectively. Gene inactivation of CT-1 was achieved by siRNA technology.

RESULTS

CT-1 as well as its receptor gp 130 were transiently upregulated during differentiation of ES cells. Exogenous CT-1 enhanced cardiomyogenesis, increased the cardiac transcription factors MEF2c, Nkx-2.5, TEAD3 and GATA4, the cardiac proteins α-actinin, MLC2a, MYH7, MLC1a, MLC2v and HCN4 as well as vascular endothelial growth factor (VEGF), platelet-derived growth factor-BB (PDGF-BB), fibroblast growth factor-2 (FGF-2) and atrial natriuretic peptide (ANP). CT-1 downregulation by small interfering RNA (siRNA) inhibited cardiomyogenesis and decreased VEGF, PDGF-BB, FGF-2 and ANP expression. CT-1 raised intracellular calcium which was abolished by the intracellular calcium chelator BAPTA, AM and thapsigargin. Moreover, CT-1 treatment increased ROS, followed by NO generation and NOS3 activation. During ES cell differentiation CT-1 was translocated to the cell nucleus. Exogenous CT-1 induced nuclear translocation of endogenous CT-1, which was inhibited by BAPTA, the NOS inhibitor L-N(G)-Nitroarginine methyl ester (l-NAME), the radical scavenger N-(2-mercaptopropionyl)-glycine (NMPG) as well as the janus kinase 2 (JAK2) inhibitor AG490 and the PI3 kinase (PI3K) inhibitor LY294002.

CONCLUSIONS

Nuclear translocation of CT-1 regulates cardiomyogenesis of ES cells and involves calcium, NO, ROS as well as CT-1 regulated signaling pathways.

Cardiotrophin-1 plasma levels are increased in patients with diastolic heart failure

Background

Cardiotrophin-1 (CT-1) is a member of the interleukin (IL-6) family of cytokines and is increased in various cardiovascular diseases, including chronic heart failure. The aim of the study was to determine if plasma CT-1 is associated with diastolic heart failure (DHF) and to investigate the relationship between CT-1 and echocardiographic parameters.

Material/Methods

Fifty-seven consecutive patients (mean age 57±8 years, 24 males) diagnosed with DHF in our clinic and 33 controls (mean age 55±7 years, 12 males) were included in the study. All study participants underwent echocardiographic evaluation and blood samples were obtained.

Results

CT-1 and NT-proBNP values were significantly higher in DHF subjects than in controls (11.30 [8.09–16.51] vs. 17.5 [8.95–28.74] fmol/mL, P=0.017 and 64 [27.5–95] vs. 82 [55.5–241] pg/mL, P=0.009, respectively). The mitral peak velocity of early diastolic filling (E), mean ratio of E to early diastolic mitral annular velocity (E/Em), and the pulmonary capillary wedge pressure (PCWP) estimated from E/Em measurements were all significantly higher in the patient group (62.27±14.69 vs. 75.67±18.85 cm/sec, 6.40±1.48 vs. 10.30±3.48, and 10 [9–11]vs. 14[12–16] mmHg, P≤0.001 for all). Lateral and septal Em were significantly lower in the patient group (10.69±1.87 vs. 8.69±2.00 cm/sec and 8.91±1.22 vs. 6.65±1.58 cm/sec, P<0.001 for both). CT-1 positively correlated with NT-proBNP (P=0.001, r=0.349), mean E/Em (P=0.003, r=0.307), and estimated mean PCWP (P=0.001, r=0.308).

Conclusions

CT-1 is elevated in patients with DHF and is associated with NT-proBNP and estimated left ventricular filling pressures.

Cardiotrophin-1 in cardiovascular regulation

Cardiotrophin (CT)-1 was discovered by coupling expression cloning with an embryonic stem cell-based model of cardiogenesis. Comparison of similarity in amino acid sequence and conformational structure indicates that CT-1 is a member of the interleukin (IL)-6 type cytokine family that shares the transmembrane signaling protein, glycoprotein (gp) 130 as a receptor. These cytokines mediate overlapping pleiotropic actions on a variety of cell types including cardiac myocytes, hepatocytes, megakaryocytes, osteoclasts, and neuronal cells. CT-lmediates its hypertrophic and cytoprotective properties through the Janus kinase/signal transducers and activators of transcription (JAK/STAT), mitogen-activated protein (MAP) kinase, phosphatidylinositol (PI) 3 kinase, and nuclear factor kappa B (NFkappaB) pathways. CT-1 gene and protein are distributed not only in the heart, but also in the pulmonary, renal, gastrointestinal, cerebral, and muscular tissues. CT-1 could also be synthesized and secreted from vascular endothelial cells and adipocytes. CT-1 has hypertrophic actions on the cardiac myocytes, skeletal muscle cells, and smooth muscle cells as well as cytoprotective actions on the cardiac myocytes, neuronal cells, and hepatocytes. CT-1 is circulating in the body, and its plasma concentration is increased in various cardiovascular and renal diseases such as hypertension, congestive heart failure, myocardial infarction, valvular heart disease, metabolic syndrome, and chronic kidney disease. Treatment with CT-1 is beneficial in experimental animal models of cardiovascular diseases. CT-1 specifically protects the cardiac myocytes from ischemic damage when CT-1 is given not only prior to the ischemia, but also given at the time of reoxygenation. Current evidence suggests that CT-1 plays an important role in the regulation of the cardiovascular system.

Cardiotrophin-1 induces tumor necrosis factor alpha synthesis in human peripheral blood mononuclear cells

Chronic heart failure (CHF) is associated with elevated concentrations of tumor necrosis factor (TNF) α and cardiotrophin-1 (CT-1) and altered peripheral blood mononuclear cell (PBMC) function. Therefore, we tested whether CT-1 induces TNFα in PBMC of healthy volunteers. CT-1 induced in PBMC TNFα protein in the supernatant and TNFα mRNA in a concentration- and time-dependent manner determined by ELISA and real-time PCR, respectively. Maximal TNFα protein was achieved with 100 ng/mL CT-1 after 3–6 hours and maximal TNFα mRNA induction after 1 hour. ELISA data were confirmed using immunofluorescent flow cytometry. Inhibitor studies with actinomycin D and brefeldin A showed that both protein synthesis and intracellular transport are essential for CT-1 induced TNFα expression. CT-1 caused a dose dependent nuclear factor (NF) κB translocation. Parthenolide inhibited both NFκB translocation and TNFα protein expression indicating that NFκB seems to be necessary. We revealed a new mechanism for elevated serum TNFα concentrations and PBMC activation in CHF besides the hypothesis of PBMC activation by bacterial translocation from the gut.

Cardiotrophin-1. Review

BACKGROUND

Cardiotrophin-1 is newly discovered chemokin with a lot of functions. Aim of our work was to describe most important of them.

METHODS

systematically scan of available scientific resources.

RESULTS

Cardiotrophin-1 stimulates the proliferation of cardiomyocytes. Cardiotrophin-1 expression and plasma values are elevated in individuals with heart failure and have high diagnostic efficacy for the heart failure. Plasma values are also an independent prognostic factor. Preliminary findings suggest that the determination of plasma cardiotrophin-1 may be useful for the follow-up of hypertensive heart disease in routine clinical practice. Cardiotrophin-1 also plays an important cardioprotective effect on myocardial damage, is a potent regulator of signaling in adipocytes in vitro and in vivo and potentiates the elevation the acute-phase proteins. Cardiotrophin-1 may play also an important protective role in other organ systems (such as hematopoietic, neuronal, developmental).

CONCLUSION

Cardiotrophin is a newly discovered chemokin with a lot of system effects and is stable in system circulation hence permitting its development in the routine clinical investigation.

Plasma level of cardiotrophin-1 as a prognostic predictor in patients with chronic heart failure

BACKGROUND

Cardiotrophin-1 (CT-1) is a member of the interleukin (IL-6) family of cytokines and is increased in patients with chronic heart failure (CHF).

AIMS

To evaluate the prognostic role of CT-1 in patients with CHF.

METHODS AND RESULTS

We measured the plasma levels of CT-1, brain natriuretic peptide (BNP), and IL-6 in 125 patients with CHF. Patients were monitored for a mean follow-up period of 2.9 years. Plasma levels of CT-1 increased with severity of CHF. There was a significant negative correlation between plasma CT-1 and left ventricular ejection fraction. There was a significant correlation between plasma CT-1 and log IL-6. During the follow-up period, 37 patients died. High plasma levels of CT-1, BNP, and IL-6 were independent predictors of mortality on stepwise multivariate analysis. The hazard ratio for mortality in patients with plasma BNP>170 pg/mL and CT-1>658 fmol/mL was 2.48 (95% confidence interval, 1.217-5.060) compared to those with plasma BNP>170 pg/mL and CT-1<658 fmol/mL (p=0.0124).

CONCLUSION

These findings indicate that plasma CT-1 measurement provides additional prognostic information and that combined levels of CT-1 and BNP are more accurate at predicting mortality in patients with CHF than either marker alone.

Cardioprotective role of cardiotrophin-1 gene transfer in a murine model of myocardial infarction

We observed the effect of cardiotrophin-1 (CT-1) gene transfer on cardiomyocytes in a murine model of myocardial infarction. Sixty male CD-1 mice weighing approximately 40 g were used in the study. Forty mice were subjected to left coronary artery ligation and randomized to receive AdCT-1 vector (treated group) or AdLacZ vector (control group) treatment, with 20 mice for each group. AdCT-1 or AdLacZ vector was directly injected into the border zone of the ischemic myocardium at six sites, 10 min after ligation (10 microl/site, 2.5 x 10(6) PFU/100 microl). Twenty mice undergoing thoracotomy and injection of an equal volume of phosphate-buffered saline solution but not coronary ligation served as sham group. Hemodynamics, histopathology and cardiomyocyte apoptosis were detected at 2 weeks after injection. Four animals in sham, nine in control, and six in treated groups died during the experiment. The remaining 41 mice were included in the study. Mean arterial pressure, left ventricular systolic pressure, and the maximum rate of left ventricular pressure rise or fall were significantly higher in treated group than in control group (P < 0.01 for all), whereas left ventricular end-diastolic pressure, infarct size, the ratio of right ventricle or lung weight to body weight, and apoptotic index were significantly lower in treated group than in control group (P < 0.01 for all). The caspase-3 activation and mitochondrial cytochrome c release were also lower in treated group than in control group (P < 0.01 for each). AdCT-1 injection significantly inhibited Fas, Bax and p53, and increased CT-1 and Bcl-2 expression in myocardium. Our results suggest that AdCT-1 vector can be effectively transfected and continued to express bioactive CT-1 protein in myocardium. CT-1 plays an important cardioprotective effect on myocardial damage in the murine model of myocardial infarction.

Cardiotrophin-1 induces interleukin-6 synthesis in human monocytes

BACKGROUND

Patients with congestive heart failure (CHF) show increased serum concentrations of cytokines like interleukin-6 (IL-6) and cardiotrophin-1 (CT-1). Additionally, monocyte function is modulated in CHF. The aim of this study was to examine if CT-1 is able to induce IL-6 in human monocytes and to investigate the underlying pathway.

METHODS

Separated peripheral blood monocytes of healthy volunteers were cultured with increasing concentrations of CT-1 for different periods. IL-6 mRNA was determined by RT-PCR or real-time PCR and IL-6 protein concentration in the supernatant by ELISA. Phosphorylation of signal transducer and activation of transcription (STAT) 3 was analyzed by western blot or by FACS analysis. To clarify the signalling pathway of CT-1 induced IL-6 expression various inhibitors of possible signal transducing molecules were used.

RESULTS

CT-1 induced IL-6 mRNA in monocytes in a time- and concentration-dependent manner. Maximal mRNA induction was detectable after 6h with 100 ng/ml CT-1. IL-6 protein also increased in a time- and concentration-dependent manner with a maximum after 48 h with 100 ng/ml CT-1. AG490 as well as SB 203580 and parthenolide blocked CT-1 induced IL-6 expression completely. AG 490 was able to inhibit STAT3 phosphorylation in western blot analysis completely. This indicates that JAK2/STAT3, p38 and nuclear factor kappaB (NFkappaB) are involved in this pathway. To exclude a possible influence of plastic adherence of monocytes on CT-1 induced IL-6 expression, we determined intracellular STAT3 phosphorylation in whole blood samples by FACS analysis and observed independently of culture conditions a CT-1 concentration-dependent STAT3 phosphorylation.

CONCLUSION

CT-1 induces IL-6 mRNA and protein expression in a time- and concentration-dependent manner. The underlying pathway is Janus kinase (JAK)2/STAT3, p38 and NFkappaB dependent. These data may explain increased IL-6 serum concentrations and altered monocyte function found in patients with CHF. Modulation of the CT-1 pathway might be a interesting strategy in the treatment of CHF.

The lack of cardiotrophin-1 alters expression of interleukin-6 and leukemia inhibitory factor mRNA but does not impair cardiac injury response

Cardiotrophin-1 (CT-1) was identified as a growth factor for cardiac myocytes and CT-1 protects myocytes from cell death. Adult CT-1(-/-) mice exhibit neural deficits including the loss of preganglionic sympathetic neurons, but their autonomic and cardiac parameters have not been examined. We used these mice to determine if the absence of CT-1 or loss of preganglionic sympathetic input altered heart rate, left ventricular pressure, cardiac contractility (dP/dt), or cell death following ischemia-reperfusion. Basal heart rate was increased in CT-1(-/-) mice, and this difference was abolished by ganglionic block. Left ventricular pressure and dP/dt were unchanged. Dobutamine stimulated similar increases in heart rate and dP/dt in both genotypes, but ventricular pressure was significantly lower in CT-1 nulls. Cardiac expression of interleukin-6 (IL-6) mRNA was increased significantly in CT-1 null mice, while leukemia inhibitory factor (LIF) mRNA was unchanged. Infarct size normalized to area at risk was no different in CT-1(-/-) mice (33.8+/-1.0% vs. 37.7+/-3.2% WT) 24h after ischemia-reperfusion. Induction of IL-6 mRNA after infarct was significantly abrogated in CT-1 null mice compared to wild-type mice, but LIF mRNA-induction remained significant in CT-1 null mice and might contribute to cardiac protection in the absence of CT-1.

Cardiotrophin-1 induces interleukin-6 synthesis in human umbilical vein endothelial cells

In patients with chronic heart failure (CHF) increased plasma concentrations of proinflammatory cytokines are found. For example, the plasma interleukin-6 (IL-6) concentration correlates with disease severity. Beside IL-6 cardiotrophin-1 (CT-1), a member of the IL-6 superfamily, is also increased in CHF. We examined whether CT-1 is able to induce IL-6 in human umbilical vein endothelial cells (HUVEC) and characterised the underlying pathway. IL-6 mRNA was determined by real-time PCR and by RT-PCR in HUVEC which were stimulated with different CT-1 concentrations and for different time periods. IL-6 concentration in the supernatant was determined by ELISA. For the pathway determination following inhibitors were used: piceatannol (signal transducer and activation of transcription (STAT)3 phosphorylation), wortmannin (phosphatiylinositol 3-kinase (PI3K)), SB203580 (p38 mitogen-activated protein kinase (MAPK)), AG490 (Janus kinase (JAK)2), PD98059 (mitogen-activated protein kinase kinase (MEK) 1/2), parthenolide (nuclear factor kappaB) and cycloheximide (protein biosynthesis). CT-1 caused a concentration- and time-dependent increase in IL-6 mRNA in HUVEC with a maximal induction seen after 6 h (2-fold compared to control) with 100 ng/ml CT-1. In the supernatant of HUVEC a concentration- and time-dependent increase of IL-6 protein was found. A maximum effect with 100 ng/ml CT-1 was found after 24 h (11-fold compared to control). AG490, SB203580, piceatannol, parthenolide and cycloheximide inhibit CT-1 induced IL-6 mRNA and protein expression whereas wortmannin and PD98059 did not inhibit IL-6 expression. CT-1 induced both IL-6 mRNA and protein in a concentration- and time-dependent manner in HUVEC. The underlying pathway includes activation of JAK2, STAT3, p38 and NFkappaB. CT-1 induced IL-6 expression and requires protein synthesis and IL-6 is not stored intracellularly. We speculate that in CHF CT-1 might be in part responsible for increased IL-6 plasma concentrations. Modulation of the CT-1 pathway may be a further strategy in CHF treatment.

Chronic cardiotrophin-1 stimulation impairs contractile function in reconstituted heart tissue

Cardiotrophin-1 (CT-1) is known to promote survival but also to induce an elongated morphology of isolated cardiac myocytes, leading to the hypothesis that CT-1, which is chronically augmented in human heart failure, might induce eccentric cardiac hypertrophy and contractile failure. To address this, we used heart tissues reconstituted from neonatal rat cardiac myocytes (engineered heart tissue, EHT) as multicellular in vitro test systems. CT-1 dose-dependently affected contractile function in EHTs. After treatment with 0.1 nM CT-1 (corresponds to plasma levels in humans) for 10 days, twitch tension significantly decreased to 0.30 +/- 0.04 mN (n = 15) vs. 0.45 +/- 0.04 mN (n = 16) in controls. Furthermore, positive inotropic effects of cumulative concentrations of Ca2+ and isoprenaline were significantly diminished. Maximum isoprenaline-induced increase in twitch tension amounted to 0.27 +/- 0.04 mN (n = 15) vs. 0.47 +/- 0.06 mN (n = 16) in controls (P < 0.001). When EHTs were treated for only 5 days, qualitatively similar results were obtained but changes were less pronounced. Immunostaining of whole mount EHT preparations revealed that after CT-1 treatment, the number of nonmyocytes significantly increased by 98% (1 nM, 10 days), and myocytes did not form compact, longitudinally oriented muscle bundles. Interestingly, expression of the Ca2+-handling protein calsequestrin was markedly reduced (69 +/- 7% of control) by treatment with CT-1 (0.1 nM, 10 days). In summary, long-term exposure to CT-1 induces contractile dysfunction in EHTs. Structural changes due to impaired differentiation and/or remodeling of heart tissue may play an important role.

Interleukin-6 Causes Myocardial Failure and Skeletal Muscle Atrophy in Rats

Background— The impact of interleukin (IL)-6 on skeletal muscle function remains the subject of controversy.

Methods and Results— The effects of 7-day subcutaneous administration of recombinant human IL-6 were examined at 3 doses, 50, 100, or 250 μg · kg −1 · d −1 , in rats. Skeletal muscle mass decreased dose-dependently (with increasing dose: in the diaphragm, −10%, P =NS; −15%, P =0.0561; and −15% P <0.05; and in the gastrocnemius, −9%, P =NS; −9%, P =NS; and −18%, P <0.005) because of decreases in cross-sectional area of all fiber types without alterations in diaphragm contractile properties. Cardiovascular variables showed a dose-dependent heart dilatation (for end-diastolic volume: control, 78 μL; moderate dose, 123 μL; and high dose, 137 μL, P <0.001), reduced end-systolic pressure (control, 113 mm Hg; moderate dose, 87 mm Hg; and high dose, 90 mm Hg; P =0.037), and decreased myocardial contractility (for preload recruitable stroke work: control, 79 mm Hg; moderate dose, 67 mm Hg; and high dose, 48 mm Hg; P <0.001). Lung edema was confirmed by an increased wet-to-dry ratio (control, 4.2; moderate dose, 4.6; and high dose, 4.5; P <0.001) and microscopy findings. These cardiovascular alterations led to decreases in organ blood flow, particularly in the diaphragm (control, 0.56 mL · min −1 · g −1 ; moderate dose, 0.21 mL · min −1 · g −1 ; and high dose, 0.23 mL · min −1 · g −1 ; P =0.037). In vitro recombinant human IL-6 administration did not cause any alterations in diaphragm force or endurance capacity.

Conclusions— IL-6 clearly caused ventilatory and peripheral skeletal muscle atrophy, even after short-term administration. Blood flow redistribution, resulting from the myocardial failure induced by IL-6, was likely responsible for this muscle atrophy, because IL-6 did not exert any direct effect on the diaphragm.

Effects of cardiotrophin-1 on hemodynamics and cardiomyocyte apoptosis in rats with acute myocardial infarction

The effects of cardiotrophin-1 on hemodynamics, cardiac function, cardiomyocyte apoptosis, and expression of P53, Fas, Bax and Bcl-2 proteins in myocardium were determined in a rat model of acute myocardial infarction. Twenty-four male Sprague-Dawley rats weighing approximately 310 g were subjected to left coronary artery ligation. Seven days before surgery, the rats were randomized to receive cardiotrophin-1 (treated group) or phosphate-buffered saline (control group). Recombinant rat cardiotrophin-1 (2 microg in 1 ml phosphate-buffered saline) or phosphate-buffered saline (1 ml) was administered daily via the tail vein for 7 days (n = 12 for each group). Hemodynamic parameters, apoptotic index, P53, Fas, Bax and Bcl-2 expression in myocardium were measured at 24 hours after coronary ligation. As compared with control animals, rats treated with cardiotrophin-1 had significantly higher mean arterial pressure, left ventricular systolic pressure and the maximum rate of left ventricular pressure rise or fall, and significantly lower left ventricular end-diastolic pressure. Cardiotrophin-1 pretreatment did not affect the heart rate, heart weight, body weight or the ratio of heart weight to body weight. The number of apoptotic cardiomyocytes in cardiotrophin-1 treated group was less than that in control group [(15.8+/-5.2) % vs (34.6+/-7.7) %, P<0.01]. Cardiotrophin-1 pretreatment significantly inhibited P53, Fas and Bax, and increased Bcl-2 expression in myocardium.

Cardiotrophin-1 is a prophylactic against the development of chronic hypoxic pulmonary hypertension in rats

BACKGROUND

Cardiotrophin-1 (CT-1) reduces arterial blood pressure by activating nitric oxide synthesis. This study attempted to elucidate the effect of CT-1 on pulmonary arteries of pulmonary hypertensive rats.

METHODS

Pulmonary hypertension was induced in rats in a hypoxic chamber containing 10% to 11% oxygen. Rats kept in the hypoxic environment received either recombinant mouse CT-1 at a concentration of 50 micro g/kg (CT-1+hypoxia group, n = 21) or phosphate-buffered saline (hypoxia group, n = 30) once per day. Control rats housed in room air also received either the equivalent concentration of CT-1 (CT-1+normoxia group, n = 18) or phosphate-buffered saline (normoxia group, n = 39). Pulmonary arterial pressure, pulmonary vasorelaxation, and ventricular hypertrophy were measured.

RESULTS

The mean pulmonary arterial pressures were as follows (from lowest to highest; p values are relative to the hypoxia group): normoxia group (20.3 +/- 4.0 mm Hg, p < 0.0001), CT-1+normoxia group (21.1 +/- 2.4 mm Hg, p < 0.0001), CT-1+hypoxia group (27.9 +/- 4.1 mm Hg, p = 0.0019), and hypoxia group (33.9 +/- 6.6 mm Hg). The endothelium-dependent vasorelaxation value was largest in the normoxia group (59.5% +/- 17.4%, p < 0.0001), with it decreasing in the other groups in the following order (p values are relative to the hypoxia group): CT-1+normoxia group (52.8% +/- 15.5%, p = 0.0005), CT-1+hypoxia group (42.3% +/- 14.8%, p = 0.0061), and hypoxia group (17.4% +/- 4.8%). Right ventricular hypertrophy was significant only in the hypoxia group.

CONCLUSIONS

Our results demonstrate that treatment with CT-1 in a chronic hypoxic pulmonary hypertension model protects the endothelial function of the pulmonary artery; decreases pulmonary arterial pressure; and attenuates right ventricular hypertrophy.

Acute effect of human cardiotrophin-1 on hemodynamic parameters in spontaneously hypertensive rats and Wistar Kyoto rats

There is considerable evidence to indicate that humoral factors play an important role in the development of left ventricular hypertrophy. Cardiotrophin-1 (CT-1) is a cytokine that has been shown to induce cardiac hypertrophy in a dose-dependent manner. The aim of the present study was to investigate the acute effect of CT-1 on hemodynamic parameters in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) and to study the relationship between the plasma concentration of CT-1 and its hemodynamic effect. Ten-week-old SHR and age-matched WKY were used. Blood pressure (BP), heart rate (HR) and plasma concentration of CT-1 were measured both before and for 60 min after intravenous bolus injection of human CT-1 (10 microg/kg). CT-1 injection significantly decreased BP and significantly increased HR in SHR and WKY. There were significant differences in BP and HR between the two groups at all time points after injection. The lowest BP, highest HR and maximal plasma concentrations of CT-1 were observed in both groups within 10 min after injection. However, after converting the values into the percentage change from their respective baselines, there were no significant differences between the two groups in BP or HR at any time point. There was also no significant difference between the two groups at any time point in the plasma concentration of CT-1. This study indicates that CT-1 decreases BP and increases HR in both SHR and WKY. The most obvious change occurred within 10 min after injection. However, there was no significant difference in the hypotensive effect of CT-1 on 10-week-old SHR and WKY.

Induction of JAB/SOCS-1/SSI-1 and CIS3/SOCS-3/SSI-3 is involved in gp130 resistance in cardiovascular system in rat treated with cardiotrophin-1 in vivo

CIS (cytokine-inducible SH2 protein), SOCS (suppressor of cytokine signaling), or SSI (signal transducers and activators of transcription [STAT]-induced STAT inhibitor) proteins are a family of cytokine-inducible negative regulators of cytokine signaling via Janus kinase (JAK)-STAT pathways. Given the evidence that the JAK-STAT pathway plays a critical role in the cardiovascular system, the primary objective of this study was to assess the effects of the CIS family on JAK-STAT signaling in the cardiovascular system in rats treated with cardiotrophin-1 (CT-1), an interleukin-6 family of cytokines. Intravenous injection of 20 microgram/kg body weight of CT-1 induced a transient, marked increase in STAT3 activation in various tissues, including heart and lung, and subsequent upregulation of 2 members of the CIS family, JAK-binding protein (JAB)/SOCS-1/SSI-1 and CIS3/SOCS-3/SSI-3, in the same tissues. It was also observed that CIS3 was directly associated with JAK2 in vivo. Pretreatment with the same dose of CT-1 60 minutes before significantly attenuated the STAT3 activation induced by a second injection of CT-1. We previously reported that intravenous injection of CT-1 results in the nitric oxide (NO)-dependent hypotension accompanied by the induction of inducible NO synthase mRNA. In rats pretreated with CT-1, the induction of inducible NO synthase mRNA or hypotension by subsequent CT-1 injection was not observed. Forced expression of JAB or CIS3, but not other CISs, directly blocked CT-1-induced STAT3 activation in 293 cells. These results suggest that JAB and CIS3 serve as endogenous inhibitors of CT-1-mediated JAK-STAT signaling in the cardiovascular system in vivo.

Plasma N terminal pro-brain natriuretic peptide and cardiotrophin 1 are raised in unstable angina

OBJECTIVE

To compare circulating concentrations of N terminal pro-brain natriuretic peptide (N-BNP) and cardiotrophin 1 in stable and unstable angina.

DESIGN AND SETTING

Observational study in a teaching hospital.

PATIENTS

15 patients with unstable angina, 10 patients with stable angina, and 15 controls.

MAIN OUTCOME MEASURES

Resting plasma N-BNP and cardiotrophin 1 concentrations.

RESULTS

N-BNP concentration (median (range)) was 714 fmol/ml (177-3217 fmol/ml) in unstable angina, 169.5 fmol/ml (105.7-399.5 fmol/ml) in stable angina (p = 0.005 v unstable angina), and 150.5 fmol/ml (104. 7-236.9 fmol/ml) in controls (p < 0.0001 v unstable angina; NS v stable angina). Cardiotrophin 1 concentration was 142.5 fmol/ml (42. 2-527.4 fmol/ml) in unstable angina, 73.2 fmol/ml (41.5-102.1 fmol/ml) in stable angina (p < 0.05 v unstable angina), and 27 fmol/ml (6.9-54.1 fmol/ml) in controls (p < 0.0005 v stable angina; p < 0.0001 v unstable angina). Log cardiotrophin 1 correlated with log N-BNP in unstable angina (r = 0.93, p < 0.0001).

CONCLUSIONS

Both circulating N-BNP and cardiotrophin 1 are raised in unstable angina, while cardiotrophin 1 alone is raised in stable angina. The role of cardiotrophin 1 and the relation between cardiotrophin 1 and N-BNP in myocardial ischaemia remain to be defined.

Effects of cardiotrophin-1 on hemodynamics and endocrine function of the heart

Cardiotrophin-1 (CT-1), a member of the interleukin-6 superfamily of cytokines, possesses hypertrophic actions and atrial natriuretic peptide (ANP)-producing activity in vitro. The goal of our study is to elucidate whether CT-1 affects the cardiovascular system in vivo. Intravenous injection of CT-1 (4-100 microg/kg) in conscious rats evoked significant declines in blood pressure and reflex increases in heart rate (HR) in a dose-dependent manner. CT-1 induced no significant change in cardiac output (from 260.7 +/- 11.0 to 264.7 +/- 26.6 ml. min(-1). kg(-1), P = not significant), which was compatible with the results from isolated perfused rat hearts; HR, change in pressure over time, left ventricular developed pressure, and perfusion pressure were unaffected. Northern blot and RT-PCR analyses revealed that CT-1 increased expression of inducible nitric oxide synthase (iNOS) in lung and aorta but not in heart or liver. Pretreatment with aminoguanidine, a specific iNOS inhibitor, inhibited both iNOS mRNA production and the depressor effect of CT-1. Interestingly, CT-1 increased ventricular expression of ANP and brain natriuretic peptide (BNP). The data demonstrate that CT-1 elicits its hypotensive effect via a nitric oxide-dependent mechanism and that CT-1 induces ANP and BNP mRNA expression in vivo.

Cardiotrophin-1: a novel cytokine and its effects in the heart and other tissues

Cardiotrophin-1 (CT-1) originally was discovered as a factor that can induce hypertrophy of cardiac myocytes, both in vitro and in vivo. Subsequently, CT-1 has been shown to have a wide variety of different effects on cardiac and noncardiac, cells including the ability to stimulate the survival of both cardiac and neuronal cells. Like other members of the interleukin-6 family of cytokines, CT-1 stimulates both the p42/p44 mitogen-activated protein kinase pathway and the Janus-activated kinase/signal transducers and activators of transcription pathway. Interestingly, whilst activation of the p42/p44 mitogen-activated protein kinase pathway is necessary for the survival-promoting effects of CT-1 in cardiac cells, it is not required for its hypertrophic effect, which is likely to involve activation of the Janus-activated kinase/signal transducer and activator of transcription-3 pathway. CT-1, therefore, may be of use as a novel cardioprotective agent, particularly if its hypertrophic effect can be specifically inhibited.

Cardiotrophin-1 (CT-1): a novel hypertrophic and cardioprotective agent

Cardiotrophin-1 (CT-1) is a member of the IL-6 family of cytokines which was originally discovered as a factor which can induce hypertrophy of cardiac myocytes both in vitro and in vivo. Subsequently, CT-1 has been shown to have a wide variety of different effects on cardiac and non cardiac cells including the ability to stimulate the survival of both cardiac and neuronal cells. Interestingly, whilst activation of the p42/p44 MAP kinase pathway is necessary for the survival promoting effects of CT-1 in cardiac cells, it is not required for its hypertrophic effect which is likely to involve activation of the Jak/STAT-3 pathway. CT-1 may therefore be of use as a novel cardio-protective agent, particularly if its hypertrophic effect can be specifically inhibited.