IL-6 is produced by splenocytes derived from CMV-infected mice in response to CMV antigens, and induces MCP-1 production by endothelial cells: a new mechanistic paradigm for infection-induced atherogenesis

Restriction of interleukin-6 alters endothelial cell immunogenicity in an allogenic environment

The microvascular endothelium of the renal transplant is the first site of graft interaction with the host immune system and is often injured in chronic Antibody Mediated Rejection (AMR). Microvascular inflammation is an independent determinant of AMR and heightens endothelial expression of HLA molecules thereby increasing the possibility of Donor Specific Antibody (DSA) binding. Endothelial cells produce IL-6 in the steady-state and this is increased by inflammation or by HLA-DR antibody binding in an allogeneic setting. Because IL-6 has been implicated in AMR, IL-6 blockade is currently under investigation as a therapeutic target. To further understand the role of IL-6 in endothelial cell immunogenicity, we have examined whether humanized antibody blockade of IL-6 altered endothelial cell interactions with allogeneic PBMC and after anti-HLA or DSA binding to endothelial cells in an in vitro human experimental model. Soluble factors, endothelial phenotype, Stat-3 activation, CD4⁺ -T differentiation, and C4d deposition were examined. Blockade of IL-6 reduced endothelial cell secretion of IL-6 and of the monocyte chemoattractant MCP-1. Pre-activation of endothelial cells by anti-HLA or DSA binding increased IL-6 secretion, that was further increased by concurrent binding of both antibodies and this was inhibited by IL-6 blockade. Activation of Stat-3 in CD4⁺ -T mediated by soluble factors produced in endothelial-PBMC interactions, and endothelial differentiation of CD4⁺ -T cell subsets (Th1, Th17, Treg), were impaired whereas activation of Complement by anti-HLA antibody binding remained unchanged by IL-6 blockade. Together, these data identify EC-mediated pro-inflammatory responses (T cell expansion, EC auto-activation, chemokine secretion) targeted by IL-6 blockade.

Restriction of interleukin-6 alters endothelial cell immunogenicity in an allogenic environment

The microvascular endothelium of the renal transplant is the first site of graft interaction with the host immune system and is often injured in chronic Antibody Mediated Rejection (AMR). Microvascular inflammation is an independent determinant of AMR and heightens endothelial expression of human leukocyte antigen (HLA) molecules thereby increasing the possibility of Donor Specific Antibody (DSA) binding. Endothelial cells (ECs) produce IL-6 in the steady-state that is increased by inflammation or by HLA-DR antibody binding in an allogeneic setting. Because IL-6 has been implicated in AMR, IL-6 blockade is currently under investigation as a therapeutic target. To further understand the role of IL-6 in EC immunogenicity, we have examined whether humanized antibody blockade of IL-6 altered EC interactions with allogeneic PBMC and after anti-HLA or DSA binding to ECs in an in vitro human experimental model. Soluble factors, endothelial phenotype, Stat-3 activation, CD4⁺ -T differentiation and C4d deposition were examined. Blockade of IL-6 reduced EC secretion of IL-6 and of the monocyte chemoattractant MCP-1. Pre-activation of ECs by anti-HLA or DSA binding increased IL-6 secretion, that was further increased by concurrent binding of both antibodies and this was inhibited by IL-6 blockade. Activation of Stat-3 in CD4⁺ -T mediated by soluble factors produced in endothelial-PBMC interactions, and endothelial differentiation of CD4⁺ -T cell subsets (Th1, Treg), were impaired whereas activation of Complement by anti-HLA antibody binding remained unchanged by IL-6 blockade. Together, these data identify EC-mediated pro-inflammatory responses (T cell expansion, EC auto-activation, chemokine secretion) targeted by IL-6 blockade.

Proteomic Analysis of Vocal Fold Fibroblasts Exposed to Cigarette Smoke Extract: Exploring the Pathophysiology of Reinke's Edema

Reinke's edema is a smoking-associated, benign, mostly bilateral lesion of the vocal folds leading to difficulties in breathing and voice problems. Pronounced histological changes such as damaged microvessels or immune cell infiltration have been described in the vocal fold connective tissue, the lamina propria Thus, vocal fold fibroblasts, the main cell type of the lamina propria, have been postulated to play a critical role in disease mediation. Yet information about the pathophysiology is still scarce and treatment is only surgical, i.e. symptomatic. To explore the pathophysiology of Reinke's edema, we exposed near-primary human vocal fold fibroblasts to medium conditioned with cigarette smoke extract for 24 h as well as 4 days followed by quantitative mass spectrometry.Proteomic analyses after 24 h revealed that cigarette smoke increased proteins previously described to be involved in oxidative stress responses in other contexts. Correspondingly, gene sets linked to metabolism of xenobiotics and reactive oxygen species were significantly enriched among cigarette smoke-induced proteins. Among the proteins most downregulated by cigarette smoke, we identified fibrillar collagens COL1A1 and COL1A2; this reduction was validated by complementary methods. Further, we found a significant increase of UDP-glucose 6-dehydrogenase, generating a building block for biosynthesis of hyaluronan, another crucial component of the vocal fold lamina propria In line with this result, hyaluronan levels were significantly increased because of cigarette smoke exposure. Long term treatment of 4 days did not lead to significant changes.The current findings corroborate previous studies but also reveal new insights in possible disease mechanisms of Reinke's edema. We postulate that changes in the composition of the vocal folds' extracellular matrix -reduction of collagen fibrils, increase of hyaluronan- may lead to the clinical findings. This might ease the identification of better, disease-specific treatment options.

Human cytomegalovirus infection and coronary heart disease: a systematic review

Background

Human cytomegalovirus (HCMV) infection is closely associated with coronary heart disease.

Main body of the abstract

In 1987, Adam et al. were the first to report an association between HCMV infection and atherosclerosis (AS), and later, many serum epidemiology and molecular biology studies showed that HCMV-infected endothelial cells play an important role in the development of AS. As patients with HCMV are generally susceptible to coronary heart disease, and with the increasing elderly population, a review of recent studies focusing on the relationships of HCMV infection and coronary heart disease is timely and necessary.

Short conclusion

The role of HCMV infection in the development of AS needs further study, since many remaining issues need to be explored and resolved. For example, whether HCMV promotes the development of coronary AS, and what the independent factors that lead to coronary artery AS by viral infection are. A comprehensive understanding of HCMV infection is needed in order to develop better strategies for preventing AS.

The Cell Biology of Cytomegalovirus: Implications for Transplantation

Interpretation of clinical data regarding the impact of cytomegalovirus (CMV) infection on allograft function is complicated by the diversity of viral strains and substantial variability of cellular receptors and viral gene expression in different tissues. Variation also exists in nonspecific (monocytes and dendritic cells) and specific (NK cells, antibodies) responses that augment T cell antiviral activities. Innate immune signaling pathways and expanded pools of memory NK cells and γδ T cells also serve to amplify host responses to infection. The clinical impact of specific memory T cell anti-CMV responses that cross-react with graft antigens and alloantigens is uncertain but appears to contribute to graft injury and to the abrogation of allograft tolerance. These responses are modified by diverse immunosuppressive regimens and by underlying host immune deficits. The impact of CMV infection on the transplant recipient reflects cellular changes and corresponding host responses, the convergence of which has been termed the "indirect effects" of CMV infection. Future studies will clarify interactions between CMV infection and allograft injury and will guide interventions that may enhance clinical outcomes in transplantation.

Atorvastatin restores arsenic-induced vascular dysfunction in rats: modulation of nitric oxide signaling and inflammatory mediators

We evaluated whether atorvastatin, an extensively prescribed statin for reducing the risks of cardiovascular diseases, can reduce the risk of arsenic-induced vascular dysfunction and inflammation in rats and whether the modulation could be linked to improvement in vascular NO signaling. Rats were exposed to sodium arsenite (100ppm) through drinking water for 90 consecutive days. Atorvastatin (10mg/kg bw, orally) was administered once daily during the last 30days of arsenic exposure. On the 91(st) day, blood was collected for measuring serum C-reactive protein. Thoracic aorta was isolated for assessing reactivity to phenylephrine, sodium nitroprusside and acetylcholine; evaluating eNOS and iNOS mRNA expression and measuring NO production, while abdominal aorta was used for ELISA of cytokines, chemokine and vascular cell adhesion molecules. Histopathology was done in aortic arches. Arsenic did not alter phenylephrine-elicited contraction. Atorvastatin inhibited Emax of phenylephrine, but it augmented the contractile response in aortic rings from arsenic-exposed animals. Sodium nitroprusside-induced relaxation was not altered with any treatment. However, arsenic reduced acetylcholine-induced relaxation and affected aortic eNOS at the levels of mRNA expression, protein concentration, phosphorylation and NO production. Further, it increased aortic iNOS mRNA expression, iNOS-derived NO synthesis, production of pro-inflammatory mediators (IL-1β, IL-6, MCP-1, VCAM, sICAM) and serum C-reactive protein and aortic vasculopathic lesions. Atorvastatin attenuated these arsenic-mediated functional, biochemical and structural alterations. Results show that atorvastatin has the potential to ameliorate arsenic-induced vascular dysfunction and inflammation by restoring endothelial function with improvement in NO signaling and attenuating production of pro-inflammatory mediators and cell adhesion molecules.

Key role of PI3Kγ in monocyte chemotactic protein-1-mediated amplification of PDGF-induced aortic smooth muscle cell migration

BACKGROUND AND PURPOSE

Vascular smooth muscle cell (SMC) migration within the arterial wall is a crucial event in atherogenesis and restenosis. Monocyte chemotactic protein-1/CC-chemokine receptor 2 (MCP-1/CCR2) signalling is involved in SMC migration processes but the molecular mechanisms have not been well characterized. We investigated the role of PI3Kγ in SMC migration induced by MCP-1.

EXPERIMENTAL APPROACHES

A pharmacological PI3Kγ inhibitor, adenovirus encoding inactive forms of PI3Kγ and genetic deletion of PI3Kγ were used to investigate PI3Kγ functions in the MCP-1 and platelet-derived growth factor (PDGF) signalling pathway and migration process in primary aortic SMC.

KEY RESULTS

The γ isoform of PI3K was shown to be the major signalling molecule mediating PKB phosphorylation in MCP-1-stimulated SMC. Using a PI3Kγ inhibitor and an adenovirus encoding a dominant negative form of PI3Kγ, we demonstrated that PI3Kγ is essential for SMC migration triggered by MCP-1. PDGF receptor stimulation induced MCP-1 mRNA and protein accumulation in SMCs. Blockade of the MCP-1/CCR2 pathway or pharmacological inhibition of PI3Kγ reduced PDGF-stimulated aortic SMC migration by 50%. Thus PDGF promotes an autocrine loop involving MCP-1/CCR2 signalling which is required for PDGF-mediated SMC migration. Furthermore, SMCs isolated from PI3Kγ-deficient mice (PI3Kγ(-/-)), or mice expressing an inactive PI3Kγ (PI3Kγ(KD/KD)), migrated less than control cells in response to MCP-1 and PDGF.

CONCLUSIONS AND IMPLICATIONS

PI3Kγ is essential for MCP-1-stimulated aortic SMC migration and amplifies cell migration induced by PDGF by an autocrine/paracrine loop involving MCP-1 secretion and CCR2 activation. PI3Kγ is a promising target for the treatment of aortic fibroproliferative pathologies.

Reduced alpha-lipoic acid synthase gene expression exacerbates atherosclerosis in diabetic apolipoprotein E-deficient mice

OBJECTIVES

To study the effects of reduced lipoic acid gene expression on diabetic atherosclerosis in apolipoprotein E null mice (Apoe(-/-)).

METHODS AND RESULTS

Heterozygous lipoic acid synthase gene knockout mice (Lias(+/-)) crossed with Apoe(-/-) mice were used to evaluate the diabetic effect induced by streptozotocin on atherosclerosis in the aortic sinus of the heart. While diabetes markedly increased atherosclerotic plaque size in Apoe(-/-) mice, a small but significant effect of reduced expression of lipoic acid gene was observed in diabetic Lias(+/-)Apoe(-/-) mice. In the aortic lesion area, the Lias(+/-)Apoe(-/-) mice exhibited significantly increased macrophage accumulation and cellular apoptosis than diabetic Lias(+/+)Apoe(-/-) littermates. Plasma glucose, cholesterol, and interleukin-6 were also higher. These abnormalities were accompanied with increased oxidative stress including a decreased ratio of reduced glutathione/oxidized glutathione in erythrocytes, increased systemic lipid peroxidation, and increased Gpx1 and MCP1 gene expression in the aorta.

CONCLUSIONS

Decreased endogenous lipoic acid gene expression plays a role in development of diabetic atherosclerosis. These findings extend our understanding of the role of antioxidant in diabetic atherosclerosis.

Human cytomegalovirus IE1 protein elicits a type II interferon-like host cell response that depends on activated STAT1 but not interferon-γ

Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary infection, establishes life-long persistence in all infected individuals. Acute hCMV infections cause a variety of diseases in humans with developmental or acquired immune deficits. In addition, persistent hCMV infection may contribute to various chronic disease conditions even in immunologically normal people. The pathogenesis of hCMV disease has been frequently linked to inflammatory host immune responses triggered by virus-infected cells. Moreover, hCMV infection activates numerous host genes many of which encode pro-inflammatory proteins. However, little is known about the relative contributions of individual viral gene products to these changes in cellular transcription. We systematically analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major transcriptional activator and antagonist of type I interferon (IFN) signaling, on the human transcriptome. Following expression under conditions closely mimicking the situation during productive infection, IE1 elicits a global type II IFN-like host cell response. This response is dominated by the selective up-regulation of immune stimulatory genes normally controlled by IFN-γ and includes the synthesis and secretion of pro-inflammatory chemokines. IE1-mediated induction of IFN-stimulated genes strictly depends on tyrosine-phosphorylated signal transducer and activator of transcription 1 (STAT1) and correlates with the nuclear accumulation and sequence-specific binding of STAT1 to IFN-γ-responsive promoters. However, neither synthesis nor secretion of IFN-γ or other IFNs seems to be required for the IE1-dependent effects on cellular gene expression. Our results demonstrate that a single hCMV protein can trigger a pro-inflammatory host transcriptional response via an unexpected STAT1-dependent but IFN-independent mechanism and identify IE1 as a candidate determinant of hCMV pathogenicity.

Macrophage LXRα gene therapy ameliorates atherosclerosis as well as hypertriglyceridemia in LDLR(-/-) mice

Liver X receptors (LXRs) are implicated in the regulation of cholesterol homeostasis, inflammatory response and atherogenesis. Administration of LXR agonists inhibits the progress of atherosclerosis, and also increases plasma triglyceride levels, representing an obstacle to their use in treating this disease. The objective of this study was to develop an alternative approach that could overcome this obstacle. Eight-week-old low-density lipoprotein receptor-deficient (LDLR(-/-)) mice were transplanted with hematopoietic stem cell (HSC)-enriched bone marrow cells transduced with lentivectors expressing either green fluorescent protein (GFP) (Lenti-SP-GFP, control) or LXRα (Lenti-SP-LXRα) driven by a synthetic macrophage promoter. At 4 weeks post-transplant, the mice were fed with a Western diet for 8 weeks and then killed. Compared with Lenti-SP-GFP mice, the Lenti-SP-LXRα mice had a 30% reduction in atherosclerotic lesions, which was accompanied by increases in levels of macrophage expression of cholesterol efflux genes apolipoprotein E and ATP-binding cassette A1, as well as decreases in plasma inflammatory cytokines interleukin-6 and tumor necrosis factor-α. Intriguingly, a 50% reduction of plasma triglyceride level was also observed. We conclude that HSC-based macrophage LXRα gene therapy ameliorates the development of atherosclerosis along with an unexpected concomitant reduction of plasma triglyceride levels in LDLR(-/-) mice. These findings highlight the potential value of macrophage LXR expression as an avenue for therapeutic intervention against atherosclerosis.

Expanded network of inflammatory markers of atherogenesis: where are we now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesis via activation of monocytes/macrophages and T lymphocytes. Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Expanded Network of Inflammatory Markers of Atherogenesis: Where Are We Now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesisviaactivation of monocytes/macrophages and T lymphocytes.Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Statins suppress interleukin-6-induced monocyte chemo-attractant protein-1 by inhibiting Janus kinase/signal transducers and activators of transcription pathways in human vascular endothelial cells

BACKGROUND AND PURPOSE

The mechanisms of anti-inflammatory actions of statins, 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase inhibitors, remain unclear. We investigated the effects of statins on interleukin (IL)-6-induced monocyte chemo-attractant protein (MCP)-1 expression and monocyte chemotaxis.

EXPERIMENTAL APPROACH

Cultures of human aortic endothelial cells (HAECs) were stimulated with IL-6 in the absence and presence of statins. Gene expression and protein secretion of MCP-1, phosphorylation of Janus kinase (JAK) and the signal transducers and activators of transcription (STAT) pathway, and human monocyte migration were examined.

KEY RESULTS

IL-6 plus its soluble receptor sIL-6R (IL-6/sIL-6R) promoted THP-1 monocyte migration, and increased gene expression and protein secretion of MCP-1, more than IL-6 alone or sIL-6R alone. Various statins inhibited IL-6/sIL-6R-promoted monocyte migration and MCP-1 expression in HAECs. Co-incubation of mevalonate and geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, reversed the inhibitory effects of statins on MCP-1 expression. Geranylgeranyl transferase inhibitor, but not farnesyl transferase inhibitor, suppressed IL-6/sIL-6R-stimulated MCP-1 expression. IL-6/sIL-6R rapidly phosphorylated JAK1, JAK2, TYK2, STAT1 and STAT3, which were inhibited by statins. Transfection of STAT3 small interfering RNA (siRNA), but not STAT1 siRNA, attenuated the ability of IL-6/sIL-6R to enhance THP-1 monocyte migration. In addition, statins blocked IL-6/sIL-6R-induced translocation of STAT3 to the nucleus.

CONCLUSIONS AND IMPLICATIONS

Statins suppressed IL-6/sIL-6R-induced monocyte chemotaxis and MCP-1 expression in HAECs by inhibiting JAK/STAT signalling cascades, explaining why statins have anti-inflammatory properties beyond cholesterol reduction.

Arsenic exacerbates atherosclerotic lesion formation and inflammation in ApoE-/- mice

Exposure to arsenic-contaminated water has been shown to be associated with cardiovascular disease, especially atherosclerosis. We examined the effect of arsenic exposure on atherosclerotic lesion formation, lesion composition and nature in ApoE-/- mice. Early post-natal exposure (3-week-old mice exposed to 49 ppm arsenic as NaAsO(2) in drinking water for 7 weeks) increased the atherosclerotic lesion formation by 3- to 5-fold in the aortic valve and the aortic arch, without affecting plasma cholesterol. Exposure to arsenic for 13 weeks (3-week-old mice exposed to 1, 4.9 and 49 ppm arsenic as NaAsO(2) in drinking water) increased the lesion formation and macrophage accumulation in a dose-dependent manner. Temporal studies showed that continuous arsenic exposure significantly exacerbated the lesion formation throughout the aortic tree at 16 and 36 weeks of age. Withdrawal of arsenic for 12 weeks after an initial exposure for 21 weeks (to 3-week-old mice) significantly decreased lesion formation as compared with mice continuously exposed to arsenic. Similarly, adult exposure to 49 ppm arsenic for 24 weeks, starting at 12 weeks of age increased lesion formation by 2- to 3.6-fold in the aortic valve, the aortic arch and the abdominal aorta. Lesions of arsenic-exposed mice displayed a 1.8-fold increase in macrophage accumulation whereas smooth muscle cell and T-lymphocyte contents were not changed. Expression of pro-inflammatory chemokine MCP-1 and cytokine IL-6 and markers of oxidative stress, protein-HNE and protein-MDA adducts were markedly increased in lesions of arsenic-exposed mice. Plasma concentrations of MCP-1, IL-6 and MDA were also significantly elevated in arsenic-exposed mice. These data suggest that arsenic exposure increases oxidative stress, inflammation and atherosclerotic lesion formation.

Detection of human cytomegalovirus in atherosclerotic carotid arteries in humans

BACKGROUND/PURPOSE

Atherosclerosis plays an important role in stroke. A microbiological infection has been suggested to be involved in the pathogenesis of atherosclerosis, in particular the human cytomegalovirus (HCMV). The objective of this study was to determine the association between HCMV infection and atherosclerosis of the internal carotid arteries in patients of Chinese Han ethnicity with ischemic stroke.

METHODS

HCMV DNA and antigen were detected in atherosclerotic internal carotid arteries from 35 patients with ischemic stroke and 20 controls from a Chinese Han ethnic population. Immunohistochemistry, in situ hybridization and polymerase chain reaction were used to detect the HCMV immediate early (IE) and late (L) antigen as well as DNA in the vascular walls.

RESULTS

We observed that the proportion of cases that tested positive for HCMV IE but not L antigen and DNA was statistically greater in stroke patients compared with the control population.

CONCLUSION

HCMV IE antigen and DNA were associated with the pathological process of atherosclerosis. The vessel wall might be the infection site of the dormant virus.

Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutical options

Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted.

Cardiovascular Consequences of Obesity and Targets for Treatment

Obesity is a risk factor for cardiovascular disease, including coronary artery disease and heart failure, but the mechanisms by which it may cause them are not completely clear. Currently, therapies aimed at obesity-related cardiovascular disease include weight loss strategies and reduction of the other risk factors that are associated with obesity and cardiovascular disease. Other pathways with for potential drug development for obesity-related CVD are also discussed.

Plasma levels of fibrinogen and C-reactive protein are related to interleukin-6 gene −572C>G polymorphism in subjects with and without hypertension

Hypertension is an important risk factor for cardiovascular diseases. There is increasing evidence suggesting that inflammation is involved in the development of hypertension. Interleukin-6 (IL-6) is an important mediator of inflammatory response and the major regulator of hepatic production of acute phase proteins, such as fibrinogen and C-reactive protein (CRP), which have been associated with hypertension and cardiovascular diseases. Therefore, we studied the association of single nucleotide polymorphism (SNP) in the IL-6 gene (IL6) promoter with plasma levels of fibrinogen, CRP and hypertension. Five hundred and two Hong Kong Chinese subjects (282 normotensives and 220 hypertensives) were recruited. IL-6 gene promoter was examined for polymorphism and the study subjects were genotyped for any SNP identified. The IL6 -572C>G polymorphism (rs1800796) was found with a frequency of 0.23 for the minor G allele. Subjects with the -572G allele had significantly higher plasma fibrinogen (3.06+/-0.57 vs 2.83+/-0.60, P=0.002) and CRP (interquartile range 0.33-1.56 vs 0.12-0.93, P=0.003) levels than those without. The -572C>G polymorphism was found to be an independent predictor of fibrinogen and CRP levels after adjusting for confounding factors. Plasma concentrations of fibrinogen and CRP correlated with systolic blood pressure. However, the -572C/G genotype frequencies did not differ between hypertensive and normotensive subjects, and there was no association between -572C>G polymorphism and blood pressure. Our results provide evidence that there is a clear genetic influence of IL6 -572C>G polymorphism on plasma levels of fibrinogen and CRP, but this polymorphism does not lead to elevated blood pressure.

Wide proinflammatory effect of electronegative low-density lipoprotein on human endothelial cells assayed by a protein array

Electronegative low-density lipoprotein (LDL(-)) is a modified subfraction of LDL present in plasma able to induce the release of interleukin 8 (IL-8) and monocyte chemotactic protein 1 (MCP-1) by human umbilical vein endothelial cells (HUVEC). To ascertain whether further inflammation mediator release could be induced by LDL(-), a protein array system was used to measure 42 cytokines and related compounds. Native LDL and LDL(-) isolated from normolipemic subjects were incubated for 24 h with HUVEC and culture supernatants were used to measure inflammation mediator release. The protein array revealed that IL-6, granulocyte/monocyte colony-stimulating factor (GM-CSF) and growth-related oncogene (GRO) release were increased by cultured HUVEC in response to LDL(-). LDL(-) enhanced production of IL-6 (4-fold vs. LDL(+)), GM-CSF (4-fold), GRObeta (2-fold) and GROgamma (7-fold) was confirmed by ELISA. Time-course experiments revealed that IL-6 was released earlier than the other inflammation mediators, suggesting a first-wave cytokine action. However, the addition of IL-6 alone did not stimulate the production of IL-8, MCP-1 or GM-CSF. Moreover, IL-8, MCP-1 or GM-CSF alone did not promote the release of the other inflammatory molecules. Modification of LDL(+) by phospholipase A(2)-mediated lipolysis or by loading with non-esterified fatty acids (NEFA) reproduced the action of LDL(-), thereby suggesting the involvement of NEFA and/or lysophosphatidylcholine in the release of these molecules. Our results indicate that LDL(-) promotes a proinflammatory phenotype in endothelial cells through the production of cytokines, chemokines and growth factors.

Interleukin-6 Polymorphism: A Genetic Risk Factor for Cardiac Transplant Related Coronary Vasculopathy?

AIMS

Interleukin- (IL-) 6 is a pleiotropic cytokine with effects on the acute phase response, inflammation, and vascular function. A G to C polymorphism has been described at position -174 in the promoter region of the IL-6 gene. We investigated the influence of this polymorphism on the development of cardiac transplant related coronary vasculopathy (CV).

METHODS

Sequence specific polymerase chain reaction identified the -174*G/C allele for 116 cardiac transplant recipients. Coronary disease was identified by routine surveillance post-transplant coronary angiography.

RESULTS

Prevalence of the -174*G/C polymorphism was different between the transplant and control cohorts; *CC 27.6%, *CG 45.7%, and *GG 26.7% vs. 13.2%, 44.1% and 42.7% respectively (p = 0.004). Median time to the first diagnosis of CV was different between the 3 alleles; *CC 2.8 years (2.0-4.0); *CG 3.9 years (2.1-4.5); *GG 5.3 years (3.2-6.1) (p = 0.05). By Kaplan-Meier survival analysis C homozygotes developed CV significantly earlier than the other cohorts (p = 0.035). At 5 years 100% of C homozygotes had evidence for CV. G homozygotes had a more gradual onset of CV with an approximate 60% prevalence at 5 years. *CC genotype was the most predictive risk factor for CV development (Hazard ratio 4.2 (95% CI 1.3-12.9); p = 0.014). Increasing donor age was also significant (Hazard ratio 1.04 (95% CI, 1.0-1.08); p = 0.023).

CONCLUSIONS

Polymorphism at position -174 within the promoter region of the IL-6 gene may be an important risk factor for cardiac transplant related coronary vasculopathy. This may improve patient selection and allow tailored immunosuppressive treatment.