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Cardiovascular Research 2000 45(2):428-436; doi:10.1016/S0008-6363(99)00262-X
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Copyright © 2000, European Society of Cardiology

CXC-chemokines, a new group of cytokines in congestive heart failure — possible role of platelets and monocytes

Jan Kristian Damåsa,b, Lars Gullestada, Thor Uelandc, Nils Olav Solumb, Svein Simonsena, Stig S Frølandd,b and Pål Aukrustd,b,*

aDepartment of Cardiology, University of Oslo The National Hospital, N-0027 Oslo, Norway
bResearch Institute for Internal Medicine, University of Oslo The National Hospital, N-0027 Oslo, Norway
cSection of Endocrinology, University of Oslo The National Hospital, N-0027 Oslo, Norway
dSection of Clinical Immunology and Infectious Diseases, Department of Internal Medicine, University of Oslo The National Hospital, N-0027 Oslo, Norway

* Corresponding author. Tel.: +47-22-86-7010; Fax: +47-22-86-8242 pal.aukrust{at}klinmed.uio.no

Received 28 April 1999; accepted 16 August 1999


   Abstract
Top
 Abstract
1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 
Objectives: The purpose of the present study was to examine the circulating levels of CXC-chemokines in patients with various degree of congestive heart failure (CHF). Background: CXC-chemokines may be important mediators in the persistent immune activation observed in CHF patients by activation of circulating neutrophils, T-cells and monocytes and possibly by the recruitment of these cells into the failing myocardium. Methods: Levels of interleukin (IL)-8, growth-regulated oncogene (GRO){alpha} and epithelial neutrophil activating peptide (ENA)-78 were measured both in serum and in platelet-free plasma by enzyme immunoassay in 47 patients with CHF and in 20 healthy controls. Results: (i) CHF patients had significantly elevated levels of all the three CXC-chemokines with IL-8 and GRO{alpha} showing a gradual increase along with increasing NYHA class. (ii) There was an inverse correlation between IL-8 and left ventricular ejection fraction (EF) and cardiac index (CI). (iii) Both unstimulated and lipopolysaccharide (LPS)-stimulated monocytes from CHF patients released markedly elevated amounts of all three CXC-chemokines. (iv) Platelets from patients with severe CHF were characterised by decreased content of GRO{alpha} and ENA-78 as well as decreased release of these chemokines upon thrombin receptor stimulation. (v) Activated platelets stimulated peripheral blood mononuclear cells in vitro to enhanced release of IL-8, and neutralising antibodies against ENA-78 inhibited this interaction. Conclusions: This study demonstrates for the first time elevated levels of CXC-chemokines in CHF, which may be of importance for progression of heart failure. Our findings further suggest that activated monocytes and platelets may contribute to enhanced CXC-chemokine levels in CHF.

KEYWORDS Cytokines; Heart failure; Infection/inflammation; Leukocytes; Platelets

This article is referred to in the Editorial by S. Sasayama et al. (pages 267–269) in this issue.


   1 Introduction
Top
 Abstract
 1 Introduction
2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 
Recent reports suggest a role for immunologic and inflammatory processes in the pathogenesis and progression of congestive heart failure (CHF) [1,2]. For example, proinflammatory cytokines such as tumor necrosis factor (TNF)-{alpha} and interleukin (IL)-1 are capable of inducing dysfunction of the cardiac muscle through direct effect on calcium dependent processes [3,4], and/or through enhanced nitric oxide production [5,6]. Recent studies have also demonstrated an important role of TNF{alpha} in induction of apoptosis [7]. IL-6 and related cytokines are potent stimulators of growth through their common receptor unit gp 130 [8,9]. Hence, there is growing evidence that proinflammatory cytokines are important factors in the remodelling process in the failing human myocardium [10,11].

The attraction of leukocytes into tissue is essential for inflammation and the host response to infection, and may also to be involved in the pathogenesis of CHF [12,13]. Chemokines, or chemotactic cytokines, are important factors in the control and regulation of this invasion of leukocytes into the inflamed tissue [14]. Chemokines are small proteins subdivided into families on the basis of the relative position of their cysteine residues [15]. In the CXC-chemokines, one amino acid separates the first two N-terminal cysteine residues. Most CXC-chemokines are potent chemoattractants and activators for neutrophils, and several functional responses including adherence to endothelium, enzyme secretion and induction of respiratory burst are observed in vitro after CXC-chemokine stimulation of these cells [16,17]. Furthermore, some reports indicate that CXC-chemokines also have other target cells than neutrophils, including T-cells and monocytes [18].

Recent studies suggest that CXC-chemokines may be involved in the pathogenesis of various heart diseases. Reperfusion of ischemic myocardium promotes influx of neutrophils involving CXC-chemokines as important contributing mediators [19]. Furthermore, a potential role in atherogenesis of IL-8 and other CXC-chemokines able to bind the IL-8 receptor CXCR-2, is receiving increasing attention [20]. However, except for some reports on raised IL-8 levels in patients with cardiogenic shock [21,22], there are to our knowledge, no in vivo data on CXC-chemokine levels in CHF.

Based on the potential pathogenic role of CXC-chemokines in activation of circulating neutrophils, T-cells and monocytes and possibly in the recruitment of these cells into the failing human myocardium, we in the present study examined the circulating levels of three different CXC-chemokines (IL-8, GRO{alpha} and ENA-78) in CHF patients with various degree of heart failure. While CXC-chemokines may be produced by a number of cell types [14,15], activated platelets and monocytes may be of particular relevance [23,24]. We therefore especially focused on the possible role of these cells, alone and in co-operation, as possible cellular sources of CXC-chemokines in CHF.


   2 Methods
Top
 Abstract
 1 Introduction
 2 Methods
3 Results
 4 Discussion
 5 Conclusion
 References
 
2.1 Subjects
Forty-seven patients with chronic symptomatic heart failure for more than 3 months, were studied. Demographic variables, heart failure classification and hemodynamic parameters for the patients are presented in Table 1. Their clinical situation was stable, with no change in medication the last month before study. Heart failure medication consisted of ACE-inhibitors (82%), diuretics (89%), and digitalis (62%), and medication in each NYHA class is presented in Table 1. Thirty-four patients were evaluated by right- and left-sided heart catheterization, by standard methods. All patients had serum creatinine levels <100 µmol/l, and none had any significant concomitant disease. Control subjects were 20 healthy sex- and age matched blood donors (Table 1). The investigation conforms with the principles outlined in the Declaration of Helsinki.


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  		Table 1 Clinical and hemodynamic characteristics of patients evaluateda

 
2.2 Blood sampling protocol
Blood was drawn into pyrogen-free tubes (Becton Dickinson, San Jose, CA) without additives (serum) and with EDTA as anticoagulant (plasma). The tubes were immediately immersed in iced water and allowed to clot for 2 h before centrifugation at 1000xg for 10 min (serum) or centrifuged within 15 min at 1000xg and 4°C for 10 min (plasma). For preparation of platelet-free plasma (PFP), another centrifugation of plasma at 11,000xg and 4°C for 10 min was performed. Both serum and plasma were stored at -80°C until analysed, and samples were thawed only once.

2.3 Stimulation of platelets in platelet–rich plasma (PRP)
Preparation and stimulation of PRP was performed as previously described [25]. Briefly, blood was drawn into sterile tubes containing citrate as anticoagulant (Becton Dickinson) and centrifuged at 240g at room temperature for 8 min immediately after collection. PRP (950 µl) containing less than 0.02x109/l leukocytes was incubated by gently tilting for 30 min at room temperature after addition of 50 µl of the thrombin receptor agonist SFLLRN (stimulated sample; final concentration 100 µM) or Tris-buffered saline (TS) only (unstimulated sample). At baseline and after 30 min, equal volumes of PRP were centrifuged at 11,000xg and 4°C for 10 min and platelet-free supernatant and platelet pellet with 1000 µl TS were stored separately at –80°C. The concentration of CXC-chemokines in platelet pellets was analysed in the lysates after lysing of pellets by freezing and thawing three times. The increase in CXC-chemokine levels (pg per 108 platelets) in platelet-free supernatants from unstimulated and stimulated platelets is expressed as the concentration in supernatant at the end of the experiment minus the concentration in the supernatant at baseline.

2.4 Stimulation of peripheral blood mononuclear cells (PBMC) with activated platelets
PBMC were obtained from heparinised blood by Isopaque-Ficoll (Lymphoprep, Nycomed Pharma AS, Oslo, Norway) gradient centrifugation within 45 min [26], and PRP and PFP from the same individuals were prepared as described above and kept at 37°C to avoid activation of platelets. PBMC were resuspended in PRP and PFP (final concentration of 3x106 PBMC/ml plasma) and incubated by gently tilting at room temperature after addition of SFLLRN (final concentration 100 µM, stimulated sample) or TS (unstimulated sample). In parallel, PBMC were also incubated with platelet-free supernatant obtained from SFLLRN-stimulated PRP as described. After 30 min, the mixtures were transferred to 96-well trays (Costar, Cambridge, MA) and cultured at 37°C in a humidified atmosphere containing 5% CO2, and cell-free supernatants were harvested after 20 h and stored at –80°C. In some experiments anti-human GRO{alpha} (final concentration 15 µg/ml), anti-human ENA-78 (final concentration 30 µg/ml) and anti-human RANTES (regulated on activation normally T-cell expressed and secreted)(final concentration 50 µg/ml) neutralising antibodies or isotype-matched control goat and mouse IgG (final concentration 50 µg/ml) (all from R&D Systems) were added to stimulated PRP 5 min before PBMC and platelets were co-incubated. Endotoxin levels were tested in all media, buffers, neutralising antibodies and stimulants used in the study and were <10 pg/ml (Limulus amebocyte test).

2.5 Isolation and stimulation of monocytes
Monocytes, isolated from PBMC by plastic adherence [26], were incubated in flat-bottomed 96-well trays (3x105 cells/ml; 200 µl/well, Costar) in medium alone (RPMI 1640 with 2 mmol/l L-glutamine supplemented with 10% foetal calf serum) or with stimulants [lipopolysaccharide (LPS) from Escherichia coli O26:B6, final concentration, 10 ng/ml, Sigma, St Louis, Mo]. After culturing for 24 h, cell-free supernatants were harvested and stored at –80°C.

2.6 Enzyme immunoassays (EIAs) for detection of IL-8, ENA-78 and GRO{alpha}
IL-8, ENA-78 and GRO{alpha} in serum, plasma and cell culture supernatants were measured by EIA (R&D Systems) according to the manufacturers’ descriptions. IL-8 levels in monocyte suspensions and PBMC/plasma co-culture, were measured by an EIA obtained from CLB, Amsterdam, The Netherlands. In our laboratory, the intra- and interassay coefficients of variation were <9% for all EIAs.

2.7 Statistical analysis
For comparison of two groups of individuals, the Mann-Whitney U test (two-tailed) was used. When more than two groups were compared, one-way ANOVA and the Bonferonni multiple comparisons procedure was employed. Data were log-transformed when necessary. Student t tests (independent) were used to evaluate mean differences between groups in the experiments on PBMC/platelet-interaction. Coefficients of correlation (r) were calculated by the Spearman's rank test. Data are given as medians and 25th to 75th percentiles if not otherwise stated. Probability values are two-sided and considered significant when <0.05.


   3 Results
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
4 Discussion
 5 Conclusion
 References
 
3.1 Serum levels of CXC-chemokines in patients with CHF
Patients with CHF had significantly elevated levels of all the three CXC-chemokines compared to healthy subjects [IL-8: 14.5 (10.0–20.5) pg/ml versus not detectable, P<0.001; GRO{alpha}: 62.3 (22.0–111.4) pg/ml versus 5.0 (0.0–5.0) pg/ml, P<0.001; ENA-78: 1064 (741.5–1661.0) pg/ml versus 517 (343–796) pg/ml, P<0.001, patients and controls, respectively]. For both IL-8 and GRO{alpha} the highest levels were found in NYHA class IV (Fig. 1), and in particular for IL-8 there was a gradual increase in serum levels along with increasing NYHA class. A significant inverse correlation was found between IL-8 and EF (Fig. 2) as well as CI (r=–0.42, P<0.01). We found significantly elevated levels of all three CXC-chemokines irrespectively of the cause of CHF with no difference between patients with idiopathic dilated cardiomyopathy and those with coronary artery disease. There have been some reports on immunomodulating effects of several drugs used in CHF, such as vesnarinone and ACE-inhibitors [27,28]. However, we found no statistical association between the use of any specific medication (Table 1) and CXC-chemokine levels.


Figure 1
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  		Fig. 1 Serum levels of CXC-chemokines in 47 CHF patients (bullet) and 20 healthy controls ({circ}) as a function of the severity of symptoms according to New York Heart Association (NYHA) functional class. Lower limit of detection of assays for IL-8, GRO{alpha} and ENA-78 were 5, 5 and 15 pg/ml, respectively. Horizontal line indicates the medians of the observations. GRO{alpha} and ENA-78 levels were only available in 46 and 43 CHF patients, respectively.

 

Figure 2
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  		Fig. 2 Correlation between left ventricular ejection fraction and serum levels of IL-8.

 
3.2 CXC-chemokine levels in platelet-free plasma (PFP)
GRO{alpha} and ENA-78 are released upon platelet activation [29], e.g. during clotting of serum ex vivo, and it is possible that elevated serum levels of these chemokines could represent an in vitro phenomenon. However, when examining CXC-chemokine levels in PFP in 14 CHF patients, (NYHA class III–IV, all with EF <35%) and six age-matched, healthy blood donors, CHF patients had significantly elevated levels of GRO{alpha} and ENA-78 also in PFP (Fig. 3). As for IL-8, no differences were found between PFP and serum levels in neither patients nor controls (data not shown).


Figure 3
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  		Fig. 3 Circulating levels of GRO{alpha} and ENA-78 analysed in platelet-free plasma (PFP) from 14 CHF patients in New York Heart Association (NYHA) functional class III–IV (NYHA class III, n=6; NYHA class IV, n=9) (bullet) and six healthy controls ({circ}). Lower limit of detection of assays for IL-8, GRO{alpha} and ENA-78 were 5, 5, 15 pg/ml, respectively. Horizontal line indicates the medians of the observations.

 
3.3 Release of CXC-chemokines from monocytes and platelets
CXC-chemokines have several cellular sources, including monocytes and platelets [15,29]. In vivo activation of these cells in CHF has been reported [23,24], and to elucidate the possible cellular sources of CXC-chemokines in CHF, we examined the ex vivo release of IL-8, GRO{alpha} and ENA-78 from platelets and monocytes in five CHF patients (all NYHA class III–IV) and six healthy controls. None were receiving aspirin or other platelet inhibitors. Platelets were activated with the thrombin receptor agonist SFLLRN and monocytes were stimulated with LPS, both known to be potent inducers of CXC-chemokines [15,30]. The relevance of choosing LPS as stimuli is further supported by very recent reports suggesting that intestinal translocation of endotoxins may be involved in the systemic inflammatory response in CHF patients [31,32].

Monocytes from CHF patients released markedly elevated amounts of all three CXC-chemokines in supernatants compared to controls, both spontaneously and after LPS stimulation for 24 h (Fig. 4) The spontaneous release of CXC-chemokines from monocytes may seem high in both patients and controls, and although this may reflect that monocytes are major contributors to the circulation, we cannot exclude some ex vivo activation of these cells during the isolation procedure, i.e. plastic adherence [33].


Figure 4
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  		Fig. 4 Levels of IL-8 (A), GRO{alpha} (B) and ENA-78 (C) in supernatants of unstimulated and LPS-stimulated (10 ng/ml) monocytes (incubated for 24 h) from five CHF patients (all in NYHA class III–IV) and six healthy controls. *P<0.05 and *P<0.01 versus controls. Data are given as medians and 25th–75th percentiles. Note that the bars for stimulated levels of IL-8 and GRO{alpha} are interrupted into two different scales.

 
Platelets from both healthy controls and CHF patients released large amount of GRO{alpha} and ENA-78 upon SFLLRN-stimulation. In contrast, although platelets from rabbit have been reported to secrete IL-8 after thrombin stimulation [34], we could not find any detectable IL-8 levels in human platelets, neither in lysates of platelet pellets nor in SFLLRN-stimulated PRP supernatants. Finally, compared to healthy controls platelets from CHF patients demonstrated two significant characteristics: (i) significantly decreased levels of both GRO{alpha} and ENA-78 in platelet pellets before stimulation, and (ii) significantly decreased release of these CXC-chemokines upon SFLLRN-stimulation (Fig. 5).


Figure 5
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  		Fig. 5 Levels of GRO{alpha} (A) and ENA-78 (B) in lysates of platelet pellets at baseline and in platelet-free supernatants of SFLLRN-stimulated (100 µM) platelets (incubated for 30 min), expressed as concentration (pg per 108 platelets) in supernatants at the end of the experiments minus concentration at baseline. *P<0.01 versus controls. Data are given as medians and 25th –75th percentiles.

 
3.4 Influence of interaction between platelets and PBMC on the release of CXC-chemokines from these cells
Since there is some evidence suggesting that interaction between monocytes and platelets may have a pathogenic role in various inflammatory disorders [35], including atherosclerotic heart disease [36], we wanted to investigate if similar interaction also could play a role in mediating enhanced release of CXC-chemokines in CHF.

PBMC were isolated from three healthy blood donors and three CHF patients (all NYHA class III–IV), co-incubated with unstimulated and SFLLRN-stimulated platelets from the same individuals (see methods). SFLLRN stimulation of PBMC and platelets separately (see above) had no effect on IL-8 secretion from these cells. However, compared with controls, PBMC from CHF patients spontaneously released elevated levels of IL-8 (Fig. 6), as observed for monocytes (Fig. 4). Furthermore, addition of unstimulated platelets had only a slight effect on the IL-8 levels (Fig. 6). In contrast, the co-incubation with SFLLRN-stimulated PRP induced a marked increase in IL-8 release from PBMC both in CHF patients (~2.5 fold) and controls (~4.5 fold). Notably, this increased IL-8 secretion from PBMC was attenuated or blocked by neutralising antibodies against ENA-78 and RANTES, but not by antibodies against GRO{alpha} (Fig. 6). Finally, also supernatants from SFLLRN-stimulated PRP induced an increase in IL-8 secretion from PBMC in controls, but this was not observed in CHF patients (Fig. 6).


Figure 6
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  		Fig. 6 Stimulation of PBMC with (SFLLRN-stimulated) platelets (Plts.) and cell-free supernatant from stimulated platelets (Supern. Stim. Plts.) in healthy controls (A) and in CHF patients (B). This co-incubation enhances IL-8 production (after 20 h) by these cells, and the response is attenuated by neutralising antibodies against ENA-78 and RANTES, but not against GRO{alpha}. Unstimulated platelets also induce a slight increase in IL-8 secretion. Note also that SFLLRN does not stimulate PBMC directly. These figures represent the mean±SE of three different experiments.

 

   4 Discussion
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
5 Conclusion
 References
 
4.1 Findings
The results of the present study, which to our knowledge is the first report of elevated circulating levels of CXC-chemokines in chronic CHF, extend previous findings suggesting a role for persistent immune activation in the pathogenesis of CHF. Notably, as for IL-8 and GRO{alpha}, the highest levels were found in patients with the most severe disease, evaluated both clinically and hemodynamically, further supporting a possible role for these chemokines in development of CHF. Finally, our findings suggest that activated monocytes and platelets may contribute for enhanced CXC-chemokine levels in CHF, partly by interacting with each other, possibly representing a vicious circle operating in CHF.

Enhanced levels of CXC-chemokines are not specific for CHF, but appear to play an important pathogenic role in several acute and chronic inflammatory diseases [14,15]. However, although without being the ultimate cause of CHF and not specific for this disorder, CXC-chemokines may be important mediators in the systemic inflammatory response observed in CHF patients, possibly contributing to the progression of disease, also taking into consideration recent reports on elevated levels of adhesion molecules and C-C chemokines [12,13].

4.2 Cellular sources of CXC-chemokines in CHF
Although CXC-chemokines may be produced by a variety of cells (e.g., T-cells, neutrophils, fibroblasts, endothelial and vascular smooth muscle cells) [14,15], our findings suggest that activated monocytes and platelets may contribute to the raised levels of CXC-chemokines in CHF. Previously, we and others have demonstrated that monocytes in CHF patients can release enhanced levels of proinflammatory cytokines (e.g., TNF-{alpha}), C–C chemokines [e.g., macrophage chemoattractant protein-1 (MCP-1)] and reactive oxygen species (ROS) [13,24]. The results of the present study further underscore the potentially important role of monocytes in the inflammatory processes in CHF.

An interesting finding in the present study was that platelets from both CHF patients and healthy control subjects upon thrombin receptor stimulation could release large amounts of GRO{alpha} and ENA-78. More importantly, our findings show that platelets in patients with severe CHF are characterised by decreased content of GRO{alpha} and ENA-78 as well as decreased release of these CXC-chemokines upon SFLLRN-stimulation ex vivo. One possibility is that this finding may reflect a significantly raised proportion of degranulated platelets in these CHF patients. Degranulated platelets may exist in circulation [37], but the release of granule content after thrombin stimulation is certainly ‘absent’. If our interpretation is correct, the increased percentage of degranulated platelets might reflect enhanced platelet activation in vivo, possibly secondary to increased in vivo exposure to agonists (e.g., thrombin). A similar pattern of decreased SFLLRN-stimulated platelet activation ex vivo has recently been reported in patients with AIDS and septic shock [25,38]. We have previously reported enhanced response to SFLLRN stimulation in some CHF patients [13], which may seem in conflict with our present finding. However, we have recently reported that while a moderate degree of platelet activation in vivo may permit enhanced response upon further stimulation, a more extensive in vivo activation of platelets may lead to degranulation resulting in decreased release upon further stimulation ex vivo [25]. Thus, one possibility is that these two reports illustrate the wide spectrum of platelet activation in the heterogeneous group of CHF patients, with the finding in the present study representing the most enhanced degree of activation. However, these conflicting results may have other interpretations, such as differently regulated release of different chemokines from platelets in CHF patients.

4.3 Platelet and PBMC interaction
Recent reports describe the induction of chemokine expression in monocytes by binding of thrombin-stimulated platelets [35]. In patients with acute myocardial infarction leukocyte-platelet adhesion is increased, and binding of activated platelets induces production and release of IL-8 in unfractionated leukocytes [36]. Interestingly, Lefer et al. lately showed that platelets and neutrophils act synergistically in provoking postreperfusion cardiac dysfunction, indicating that release of cytokines and ROS may reduce the contractile performance [39]. We hypothesise that monocyte and platelet interaction could also contribute to elevated levels of CXC-chemokines in CHF. In support of this, we found that SFLLRN-stimulated platelets can stimulate PBMC to enhanced release of IL-8 in both CHF patients and controls. Weyrich et al. have previously reported that P-selectin and RANTES may be involved in this platelet-mediated activation of monocytes [35]. In the present study we demonstrate that ENA-78 also is involved in this process. ENA-78 is known to be a potent activator of neutrophils, but our findings suggest that this CXC-chemokine also may stimulate mononuclear cells for enhanced IL-8 release. We found that the release of CXC-chemokines from platelets in CHF patients when further stimulated ex vivo by SFLLRN is reduced comparing healthy controls (see above), and in line with this, the enhancing effect of SFLLRN-stimulated platelets and in particular the stimulating effect of supernatants from stimulated platelets, was reduced in CHF patients comparing controls. However, as discussed above, this does not exclude that such an interaction may be of particular importance in CHF patients in vivo. In fact, we believe that the interaction between platelets and monocytes may be an important mediator of the systemic inflammatory response in CHF patients, and we suggest that CXC-chemokines may be important participants in this process.

4.4 Possible pathophysiological mechanisms of circulating CXC-chemokines in CHF
The ability of CXC-chemokines to enhance ROS generation in both neutrophils and monocytes may be of particular importance in the systemic inflammatory response in CHF [16,17]. Moreover, while CXC-chemokines may enhance ROS generation, these oxygen radicals may themselves increase production of certain CXC-chemokines (e.g., IL-8) and enhance platelet activation [40]. Furthermore, there are reports indicating that IL-8 induces an increase in the expression of tissue factor in monocytes representing an enhancement of procoagulant activity [41], possibly linking inflammatory responses to thrombotic events, also taking into consideration that chemokines are potent activators of the vascular endothelium.

There are some reports in animal models indicating that chemokines and their receptors may be expressed in the myocardium, possibly directly participating in the development of heart failure [42,43]. However, at present there are no data on chemokine expression in the failing myocardium in humans. Nevertheless, we suggest that CXC-chemokine may play an important role in the development of a systemic inflammatory response in CHF, and CXC-chemokines may play a particular role in the development of enhanced oxidative stress and procoagulant activity in CHF patients.


   5 Conclusion
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
References
 
This study, for the first time, demonstrates elevated levels of CXC-chemokines in CHF patients. This ‘new’ group of cytokines may be involved in the pathogenesis of CHF by being important mediators in the persistent immune activation observed in CHF. The interaction between activated platelets and monocytes may be of particular importance in this inflammatory process. However, further explorations on myocardial expression of chemokines are clearly needed to clarify the potential role of these mediators in attracting leukocytes into the failing myocardium.

Time for primary review 30 days.


   Acknowledgements
 
This work was supported by the Norwegian Council of Cardiovascular Disease, Research Council of Norway, Medinnova Foundation and Professor Paul A. Owren's Fund. We thank Anne Brunsvig, Karin Lund Pah, Bodil Lunden and Turid Pedersen for excellent technical assistance, and Kathrine Frey for assistance in data analysis.


   References
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 

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