Torbjørn Holm

Increased gene expression of tumor necrosis factor superfamily ligands in peripheral blood mononuclear cells during chronic heart failure.

OBJECTIVE Inflammation may play a pathogenic role in chronic heart failure (CHF). The objective of the study was to characterise the imbalance in the cytokine network in CHF. METHODS cDNA expression arrays were used to analyse the gene expression of cytokines and related mediators in peripheral blood mononuclear cells (PBMC) from CHF patients (n=8) and healthy controls (n=8). Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the gene expression of individual genes in additional 12 patients and eight controls. RESULTS From 375 genes, 34 were upregulated and two downregulated in CHF patients in the cDNA expression array experiments. Regulated genes included chemokines/-receptors, members of the transforming growth factor beta superfamily, orphan receptors and in particular several members of the tumor necrosis factor (TNF) superfamily. Thus, 4-1BB ligand (L), APRIL, CD27L, CD40L, FasL, LIGHT, TRAIL-receptor 4 were upregulated, while TRAIL-receptor 3 was downregulated. Real-time quantitative RT-PCR confirmed significantly upregulated gene expression of APRIL, LIGHT, FasL and CD27L in CHF patients and showed in addition significantly enhanced gene expression of TNFalpha and TRAIL. CONCLUSION The present study demonstrates differential gene expression in PBMC of several members of the cytokine network in CHF. In particular, the enhanced expression of several ligands in the TNF superfamily may reflect a potential pathogenic role of these cytokines in CHF.

Effect of pravastatin on plasma markers of inflammation and peripheral endothelial function in male heart transplant recipients

Statins appear to have several biologic effects beyond those of lipid metabolism, and we hypothesized that immunomodulating effects of statins are important for the beneficial effects of these medications after heart transplantation. Our findings suggest that pravastatin treatment reduces plasma markers of inflammation and improves peripheral endothelial function in heart transplant recipients, possibly contributing to the observed clinical benefits of statin treatment in these patients.

Plasma C-reactive protein as a marker of cardiac allograft vasculopathy in heart transplant recipients.

OBJECTIVES This study was initiated to determine whether heart transplant recipients (HTRs) with cardiac allograft vasculopathy (CAV) have increased levels of high-sensitivity C-reactive protein (hsCRP) and to examine whether an increase in hsCRP after heart transplantation predicts the development of CAV. Furthermore, the effect of pravastatin on plasma levels of hsCRP in HTRs was investigated. BACKGROUND The relationship between CAV and hsCRP, as well as the effect of statins on hsCRP in HTRs, has not been well established. METHODS On referral for their annual angiographic control study, 150 consecutive HTRs (mean 6.5 years since transplantation) were included. Plasma levels of hsCRP were measured before angiography and compared with patients with (n = 52) and without (n = 98) CAV. In 49 of these patients, we additionally analyzed hsCRP in blood samples stored from their six-month visit after the transplantation procedure. Furthermore, in a randomized, crossover study, hsCRP was analyzed in 17 male HTRs before and after six weeks of treatment with 20 mg pravastatin. RESULTS Median levels of CRP were elevated among patients with CAV compared with those with normal angiograms [3.86 (1.78 to 7.00) vs. 1.08 (0.72 to 2.13) mg/l, p < 0.001]. Prospectively evaluated hsCRP levels from six months to follow-up were significantly higher among those who developed CAV compared with those with normal angiograms [+2.76 (1.56 to 5.00) vs. +0.07 (-0.57 to 0.41) mg/l, p < 0.001]. On multivariate analysis, the increase in hsCRP was the only significant predictor of CAV. Six weeks of treatment with pravastatin significantly reduced hsCRP levels by 25%, without any relation to changes in lipid values. CONCLUSIONS Elevated plasma levels of CRP are associated with angiographic evidence of CAV, and the increase in hsCRP is a strong predictor of development of CAV. Statin treatment reduces levels of hsCRP and should be used in HTRs, regardless of their lipid levels.

Folic acid treatment reduces elevated plasma levels of asymmetric dimethylarginine in hyperhomocysteinaemic subjects.

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, has been suggested to be a novel risk factor for endothelial dysfunction. It has previously been reported that hyperhomocysteinaemia may be associated with impaired endothelium-dependent vasodilation and reduced plasma level of NO-derived endproducts (NOx). In the present study, plasma levels of arginine and ADMA were measured in twenty-one healthy control subjects, and in twenty-one hyperhomocysteinaemic subjects before and after 6 weeks and 12 months of folic acid supplementation, and compared with previously measured plasma NOx values in the hyperhomocysteinaemic subjects. Compared with control subjects, hyperhomocysteinaemic subjects had higher plasma levels of arginine and ADMA. More importantly, folic acid therapy significantly reduced plasma levels of arginine and ADMA. Furthermore, plasma levels of arginine and ADMA were positively correlated with plasma homocysteine levels and negatively correlated with plasma folate, as well as negatively correlated with plasma NOx. Our results suggest that ADMA may be a mediator of the atherogenic effects of homocysteine.

Folic Acid Treatment Reduces Chemokine Release From Peripheral Blood Mononuclear Cells in Hyperhomocysteinemic Subjects

Elevated plasma homocysteine concentration is an independent risk factor for cardiovascular disease. However, the mechanisms by which hyperhomocysteinemia induces vascular disease are uncertain. An early step in atherogenesis involves leukocyte migration into the arterial wall, a process regulated in part by chemokines. We hypothesized that homocysteine may exert its atherogenic effect in part through chemokine-mediated mechanisms, and in the present study, we examined the effects of folic acid supplementation for 6 weeks on chemokine levels in hyperhomocysteinemic individuals. Data showed the following: (1) Compared with control subjects, hyperhomocysteinemic subjects had elevated plasma levels of the CXC chemokines, epithelial neutrophil-activating peptide (ENA)-78 (P <0.05), and growth-regulated oncogene (GRO)&agr; (P =0.088), and homocysteine was significantly correlated with ENA-78 and GRO&agr;. (2) During folic acid treatment, normalization of homocysteine levels was accompanied by a marked reduction in oxidized low density lipoprotein–stimulated release of CXC chemokines (ie, GRO&agr;, ENA-78, and interleukin-8) and CC chemokines (ie, monocyte chemoattractant peptide-1 and RANTES) in peripheral blood mononuclear cells from these individuals. (3) The oxidized low density lipoprotein–induced release of ENA-78 from peripheral blood mononuclear cells from control subjects was significantly reduced when cells were incubated in the presence of folic acid. These data may suggest that homocysteine exerts atherogenic effects in part by enhancing chemokine responses in cells involved in atherogenesis and that folic acid supplementation may downregulate these inflammatory responses.

Effect of folic acid treatment on endothelium-dependent vasodilation and nitric oxide-derived end products in hyperhomocysteinemic subjects.

PURPOSE An elevated plasma homocysteine concentration is an independent risk factor for cardiovascular diseases. In this study, we tested the hypothesis that hyperhomocysteinemia induces endothelial dysfunction mediated, at least in part, through nitric oxide-dependent mechanisms and that folic acid supplementation improves endothelial function in hyperhomocysteinemic subjects. SUBJECTS AND METHODS Endothelial function was evaluated in healthy controls and hyperhomocysteinemic subjects by measuring plasma levels of the nitric oxide-derived end products nitrite and nitrate and by assessing vasodilatory responses in the skin microcirculation and forearm vasculature. In the subjects with hyperhomocysteinemia, these measurements were repeated after 6 weeks and 12 months of folic acid supplementation. RESULTS Compared with healthy controls, hyperhomocysteinemic subjects had significantly lower median plasma levels of nitric oxide-derived end products (12.1 microM [range 4.4 to 41.8] versus 24.6 microM [13.6 to 53.2]; P <0.001), a significantly lower endothelium-dependent vasodilatory response to acetylcholine (P <0.01), hyperemic response in the microcirculation (P <0.01), and total forearm blood flow during reactive hyperemia (P = 0.01). There was no significant difference in the endothelium-independent response. Folic acid treatment for 12 months increased the plasma level of nitric oxide-derived end products by 121% (95% confidence interval [CI], 72% to 170%), the vasodilatory response to acetylcholine by 124% (95% CI, 36% to 212%), and the ischemia-mediated hyperemic responses in the microcirculation by 60% (95% CI, 25% to 96%) and in the forearm vasculature by 47% (95% CI, 21% to 73%). CONCLUSIONS Homocysteine appears to induce its atherogenic effect, at least in part, by depressing endothelial function, possibly through nitric oxide-dependent mechanisms. This effect can be reversed by folic acid supplementation.

Possible role of proinflammatory cytokines in heart allograft coronary artery disease

Transplant coronary artery disease (Tx-CAD) is the main determinant of long-term prognosis after heart transplantation. Immunologic processes may play a central role in the development of Tx-CAD, but the pathogenesis has not been fully clarified. We examined plasma levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukins (IL)-1beta and IL-6, and the CC-chemokine macrophage chemoattractant protein-1 (MCP-1) in 62 cardiac allograft recipients undergoing yearly heart catherization with coronary angiography for evaluation of graft disease. In this cross-sectional study, we found significantly increased levels of IL-1beta, IL-6, TNF-alpha, and MCP-1 compared with healthy controls even several years (median 7 years) after transplantation in periods with no intercurrent illness. Although no significant differences were found in plasma levels of IL-1beta and TNF-alpha between patients with (n = 25) and without (n = 37) Tx-CAD, the Tx-CAD group had significantly increased levels of IL-6 and MCP-1 compared with both controls and transplant recipients without Tx-CAD. Increased IL-6 levels compared with controls were found only in patients with Tx-CAD. Finally, while there was no significant relation between Tx-CAD and altered lipid status, the combination of high plasma concentrations of IL-6 or MCP-1 and high low-density lipoprotein cholesterol was strongly associated with increased occurrence of Tx-CAD. These findings indicate that cardiac allograft recipients have a persistent immune activation long term after transplantation. This activation, as particularly reflected in increased MCP-1 and IL-6 levels, may be related to the development of Tx-CAD.

Peripheral endothelial dysfunction in heart transplant recipients: possible role of proinflammatory cytokines.

Endothelium‐dependent vasodilation in the peripheral circulation may be impaired in heart transplant recipients (HTx rec). Conflicting results have been obtained and the mechanisms involved have not been examined. In the present study, we examined whether long‐time survivors of heart transplantation (Tx) show signs of endothelial dysfunction in the peripheral microcirculation, and further investigated the possible role of endothelium‐related markers and proinflammatory cytokines in this process. The vasodilatory responses to acetylcholine (Ach) (endothelium‐dependent) and sodium nitroprusside (SNP) (endothelium‐independent) were evaluated by skin laser–Doppler perfusion measurements in 63 clinically stable HTx rec 6 yr (range 1–13 yr) after Tx, and compared with 20 healthy controls. Ten HTx rec were also followed prospectively with three repeated measurements during the first year after Tx. Plasma von Willebrand factor, big‐endothelin (b‐ET), and proinflammatory cytokines were measured by enzyme immunoassays. Vascular responses to both Ach and SNP were significantly attenuated in the HTx rec compared with controls. In longitudinal testing, there was a significant reduction in endothelium‐dependent vasodilation, but not independent vasodilation from 1 to 12 months after Tx. Plasma levels of vWF and b‐ET, as well as levels of proinflammatory cytokines, tumor necrosis factor (TNF)‐α, interleukin (IL)‐6 and IL‐1β, were all markedly increased in HTx rec. HTx rec responses to Ach were negatively correlated to TNF‐α levels in plasma (r=−0.39, p<0.01). Moreover, there was also a significant positive correlation between plasma b‐ET and TNF‐α (r=0.34, p<0.01). In the long‐term follow‐up of HTx rec, endothelial dysfunction is demonstrated by both regulation of blood flow in the skin microcirculation and by raised markers of endothelial activation in plasma. This endothelial dysfunction may be related to enhanced levels of proinflammatory cytokines in these patients.

CXC-chemokines in coronary artery disease: possible pathogenic role of interactions between oxidized low-density lipoprotein, platelets and peripheral blood mononuclear cells

Summary.  CXC‐chemokines may be involved in atherogenesis. Herein we examined the possible role of CXC‐chemokines in the inflammatory interactions between oxidized (ox‐) low‐density lipoprotein (LDL), platelets and peripheral blood mononuclear cells (PBMC) in 15 patients with coronary artery disease (CAD) without ‘traditional’ risk factors and 15 carefully matched controls. Our main findings were: (a) ox‐LDL stimulated the release of the CXC‐chemokines interleukin (IL)‐8, ENA‐78 and GRO‐α from PBMC, particularly in CAD. (b) In platelets, ox‐LDL induced release of ENA‐78 and, when combined with SFLLRN, also of GRO‐α, with significantly higher response in CAD. (c) Platelet‐rich plasma, especially when costimulated with ox‐LDL, enhanced the release of IL‐8 from PBMC, particularly in CAD patients. (d) Freshly isolated PBMC showed markedly increased IL‐8 mRNA expression in CAD patients. Our findings suggest enhanced inflammatory interactions between ox‐LDL, platelets and PBMC in CAD patients involving CXC‐chemokine related mechanisms, possible contributing to atherogenesis in these and other CAD patients.

Omega-3 fatty acids enhance tumor necrosis factor-alpha levels in heart transplant recipients.

BACKGROUND Proinflammatory cytokines may contribute to clinical complications in heart transplant (HTx) recipients. Previous studies have shown immunomodulating effects of omega-3 fatty acids, but the results are somewhat conflicting. In this study, we examined plasma levels of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 10, and their relations to antioxidant vitamins in 45 HTx recipients before and after treatment with omega-3 fatty acids or placebo. METHODS The patients were long-time survivors of heart transplantation, randomized in a double-blind fashion to receive omega-3 fatty acids (3.4 g/day) or placebo for 1 year. Plasma levels of cytokines were measured by enzyme immunoassays and vitamin A, vitamin E, and beta-carotene by high-performance liquid chromatography. RESULTS In the omega-3, but not in the placebo group, there was a rise in the proinflammatory cytokine TNF-alpha (P<0.05), a decrease in the anti-inflammatory cytokine IL-10 (P=0.07), and a rise in TNF/IL-10 ratio (P<0.05) after 12 months, suggesting a proinflammatory net effect. In the omega-3 group, the increase in TNF-alpha was associated with an increase in eicosapentaenoic acid in plasma (r=0.58, P<0.02). During omega-3 fatty-acid treatment, but not during placebo, there was a decrease in vitamin E (P<0.05) and beta-carotene (P<0.05) levels, and the decrease in vitamin E was inversely correlated with the increase in TNF-alpha (r= -0.56, P<0.01). The rise in TNF-alpha levels during omega-3 fatty acids treatment was most pronounced in those patients with transplant coronary artery disease (P<0.04). CONCLUSION Our data suggest that omega-3 fatty acids in HTx recipients may change the balance between proinflammatory and anti-inflammatory cytokines in an inflammatory direction, possibly related to prooxidative effects of these fatty acids.