Blood glutathione as a marker of cardiac allograft vasculopathy in heart transplant recipients

Plasma total cysteine and cardiovascular risk burden: action and interaction

We hypothesized that redox analysis could provide sensitive markers of the oxidative pathway associated to the presence of an increasing number of cardiovascular risk factors (RFs), independently of type. We classified 304 subjects without cardiovascular disease into 4 groups according to the total number of RFs (smoking, hypertension, hypercholesterolaemia, hyperhomocysteinaemia, diabetes, obesity, and their combination). Oxidative stress was evaluated by measuring plasma total and reduced homocysteine, cysteine (Cys), glutathione, cysteinylglycine, blood reduced glutathione, and malondialdehyde. Twenty-seven percent of subjects were in group 0 RF, 26% in 1 RF, 31% in 2 RF, and 16% in ≥3 RF. By multivariable ordinal regression analysis, plasma total Cys was associated to a higher number of RF (OR = 1.068; 95% CI = 1.027–1.110, P = 0.002). Total RF burden is associated with increased total Cys levels. These findings support a prooxidant effect of Cys in conjunction with RF burden, and shed light on the pathophysiologic role of redox state unbalance in preclinical atherosclerosis.

Adenovirus-mediated overexpression of glutathione-s-transferase mitigates transplant arteriosclerosis in rabbit carotid allografts

BACKGROUND

Cardiac transplant arteriosclerosis or cardiac allograft vasculopathy remains the leading cause of graft failure and patient death in heart transplant recipients. Endothelial cell injury is crucial in the development of human atherosclerosis and may play a role in allograft vasculopathy. Glutathione-S-transferase (GST) is known to protect endothelial cells from damage by oxidants and toxins. However, the contribution of human GST A4-4 (hGSTA4-4) to vascular cell injury and consequent transplant arteriosclerosis is unknown.

METHODS

A recombinant adenoviral vector containing hGSTA4-4 gene was constructed and delivered to vascular endothelial cells in an in vivo rabbit carotid artery transplant model. Forty-five days after transplantation, allografts were harvested (n=28). Blood flow was measured by ultrasonography. In addition, grafts were analyzed by histology, morphometry, immunostaining, and western blot.

RESULTS

The severity of arteriosclerosis in hGSTA4-4 transduced allografts was compared with control by measuring degree of stenosis by neointima. Decrease in blood flow in hGSTA4-4 transduced allografts was significantly less than control allografts, which also developed greater intimal thickening and stenosis than hGSTA4-4 transduced allografts in the proximal and distal regions of the graft. Leukocyte and macrophage infiltration was reduced in hGSTA4-4 transduced carotid arteries.

CONCLUSION

Our data indicate that hGSTA4-4 overexpression protects the integrity of vessel wall from oxidative injury, and attenuates transplant arteriosclerosis.

Methionine challenge paradoxically induces a greater activation of the antioxidant defence in subjects with hyper- vs. normohomocysteinemia

To determine whether hyperhomocysteinemia induced post-methionine loading (PML) is associated with different response in the aminothiol redox state and oxidative stress vs. normohomocysteinemia, we assessed PML plasma thiols, vitamins, free malondialdehyde (MDA), and blood reduced glutathione (GSH) in 120 consecutive subjects (50 [35-56] years, 83 males), divided into two groups according to PML plasma total Hcy < 35 microM (Group 1, n = 65) or > or = 35 microM (Group 2, n = 55). In the group as a whole, plasma reduced cysteine and cysteinylglycine, blood reduced GSH (all p for time = 0.0001) and plasma total GSH (p for time = 0.001) increased from baseline to PML. MDA values were unchanged. Group 1 and 2 differed in blood reduced GSH (p for group = 0.004, higher in Group 2), and MDA levels (p for group = 0.024, lower in Group 2). The oxidative stress induced by methionine challenge seems to be opposed by scavenger molecules activation, namely GSH, and lipid peroxidation does not increase. This mechanism paradoxically appears to be more efficient in hyperhomocysteinemic subjects.

Plasma glutathione levels are independently associated with gamma-glutamyltransferase activity in subjects with cardiovascular risk factors

To investigate whether GGT (gamma-glutamyltransferase) is associated to specific redox patterns. GGT, total and reduced aminothiols and malondialdehyde, were measured in 150 subjects (83 males, 48 (39-56) years), with none, one or more risk factors. By univariable analysis GGT was positively associated with age (p =0.001), male gender (p <0.001), risk factor number (p <0.001), ACE-inhibitors (p =0.008), anti-platelet agents (p =0.029), atherothrombotic events (p =0.001), glucose (p =0.013), malondialdehyde (p =0.029), plasma total cysteine (p =0.046) and inversely associated with plasma total glutathione (p =0.001). By multivariable analysis only male gender (p <0.001), risk factor number (p <0.001) and glutathione (p <0.001) were independently associated with GGT activity. These findings suggest that an ongoing redox imbalance, in terms of decreased plasma glutathione, is associated with raised GGT activity in subjects with a greater risk factor burden.

Aminothiol redox alterations in patients with chronic heart failure of ischaemic or non-ischaemic origin

OBJECTIVE

Oxidative stress plays a role in the progression of chronic heart failure (CHF), but whether and how ischaemic heart disease (IHD) or non-IHD aetiology may account for differential redox alterations is currently unclear. We assessed the relation between thiol redox state and lipid peroxidation, as a marker of oxidative stress, in patients with CHF of ischaemic or non-ischaemic origin.

METHODS

Blood reduced glutathione, plasma total and reduced cysteine, cysteinylglycine, homocysteine, glutathione, plasma alpha-tocopherol, ascorbic acid, and free malondialdehyde were assessed in 43 CHF heart transplant candidates (24 IHD and 19 non-IHD) and 30 controls matched for age, gender and number of atherosclerotic risk factors.

RESULTS

Reduced cysteine was increased in CHF patients compared with controls. The highest levels were found in IHD versus non-IHD patients versus controls. Malondialdehyde levels were significantly higher in IHD patients than in controls, whereas antioxidant vitamins did not differ among the three groups.

CONCLUSIONS

Specific abnormalities in the thiol pattern are associated with heart failure aetiology in CHF patients. Our findings point to the possible role of reduced cysteine in the progression of chronic IHD to heart failure status, as an additional pro-oxidant stimulus for worsening oxidative stress.

Inflammation/oxidation in chronic rejection: apolipoprotein a-i mimetic peptide reduces chronic rejection of transplanted hearts

BACKGROUND

Chronic rejection in transplanted hearts or cardiac allograft vasculopathy (CAV) is the leading cause of late death among heart transplant recipients. Strategies to control CAV traditionally have focused on lymphocyte functions. We hypothesized that D-4F, an apoA-I mimetic peptide with potent anti-inflammatory/antioxidant properties, will attenuate CAV.

METHODS

We used a previously characterized murine model of CAV. B6.C-H2 hearts were heterotopically transplanted into C57BL/6 mice. Recipient mice were treated with either 20 microg of D-4F or carrier daily. Donor hearts were harvested on day 24 after transplantation.

RESULTS

Treatment of recipients with D-4F reduced the severity of intimal lesions (62.5+/-3.4% vs. 31.1+/-8.7%, P<0.009). Treatment also resulted in a decrease in the number of graft-infiltrating CD4 and CD8 lymphocytes and CXCR3+ T-lymphocyte subsets. Heme oxygenase-1 (HO-1) gene transcript in the donor hearts was up-regulated with D-4F treatment, and HO-1 blockade partially reversed the beneficial effects of D-4F. In vitro studies showed that D-4F reduced allogeneic T-lymphocyte proliferation and effector cytokine production. These processes were HO-1 independent.

CONCLUSION

This study suggests that D-4F, a prototypical apoA-I mimetic peptide, is effective in controlling CAV via induction of HO-1 in the graft and a direct effect on T-lymphocyte function. This class of peptides with anti-inflammatory/antioxidant properties provides a novel strategy in the treatment of CAV.

Low plasma glutathione levels after reperfused acute myocardial infarction are associated with late cardiac events

OBJECTIVE

To clarify whether an altered redox state persists in the subacute phase of myocardial infarction and if specific redox patterns are associated with later cardiac events.

METHODS

Ninety-seven patients [80 men, median 63 (interquartile range, 53, 69) years] with a first acute myocardial infarction, with (53%) or without ST segment elevation, treated with successful percutaneous interventions, were tested at 5-6 days after admission for plasma alpha-tocopherol, ascorbic acid, total and reduced homocysteine, cysteine, glutathione, cysteinylglycine and blood-reduced glutathione, all assessed by high-pressure liquid chromatography. Free malondialdehyde was evaluated by gas chromatography. A subgroup of 14 patients had adjunctive blood samples within 1 h and at 72 h after angioplasty. Blood samples from 44 patients matched for age, sex, and risk factors served as controls. Patients were followed up for median 15 (interquartile range, 9, 17) months for cardiac events.

RESULTS

All plasma-reduced aminothiols, vitamins and plasma total glutathione were significantly lower in myocardial infarction at 5-6 days than in controls. In the 14 myocardial infarction patients sampled repeatedly, plasma-reduced glutathione, cysteinylglycine, total glutathione, and alpha-tocopherol significantly decreased, whereas blood-reduced glutathione, total homocysteine, and cysteine significantly increased over time. During follow-up, 20 of 97 (21%) patients had adverse cardiac events. Multivariate analysis revealed that only plasma-reduced glutathione was independently associated with events (hazard ratio 0.42, 95% confidence interval 0.18-0.99, P=0.04).

CONCLUSIONS

Acute myocardial infarction patients have an altered redox state at 5-6 days after successful reperfusion with respect to controls. Low plasma levels of reduced glutathione at discharge are associated with cardiac events at follow-up.

Cytoprotective Gene HO-1 and Chronic Rejection in Heart Transplantation

Chronic rejection in transplanted hearts or cardiac allograft vasculopathy (CAV) is the leading cause of late death among heart transplant recipients. We hypothesized that induction of HO-1 by D4-F, an apoA-I mimetic peptide with potent antiinflammatory/antioxidant properties, attenuated CAV. We utilized a previously characterized murine model of CAV. B6.C-H2(bml2) hearts were heterotopically transplanted into C57BL/6 mice. In the control group, recipient mice were treated with 20 microg of saline daily. In experimental group I, mice were treated daily with 20 microg of D4-F. In experimental group II, mice were treated daily with 20 microg of D4-F daily, plus CuPP, which does not have any effect on HO-1 activity. In experimental group III, recipient mice were treated with 20 mug of D4-F daily, plus SnPP, which is a competitive inhibitor of HO-1. Donor hearts were harvested on day 24 after transplantation. The donor hearts in the control group developed severe intimal lesions. In experimental group I, treatment with D4-F was associated with upregulation of HO-1 and a marked reduction in intimal lesions, which was consistent in experimental group II. In experimental group III, inhibition of HO-1 was associated with partial restoration of intimal lesions. Induction of HO-1 by an apoA-1 mimetic peptide was effective to control CAV. This class of antiinflammatory peptides, which show an ability to induce HO-1, provides a novel strategy for the treatment of CAV.

Plasma cysteine and glutathione are independent markers of postmethionine load endothelial dysfunction

OBJECTIVES

Oxidative stress caused by acute hyperhomocysteinemia impairs endothelial function in human arteries. We sought to identify markers of endothelial dysfunction during methionine-induced hyperhomocysteinemia.

DESIGN AND METHODS

35 subjects underwent flow-mediated dilation (FMD) of the brachial artery by high-resolution ultrasonography and fasting blood samples before and 3 h postmethionine load (PML). Clinical, conventional biochemical, and redox status (plasma total and reduced homocysteine, glutathione, cysteine, cysteinylglycine, ascorbic acid, alpha-tocopherol, free malondialdehyde, blood glutathione) data were sequentially entered into an univariate and multivariate stepwise linear regression analysis to evaluate their relation with the dependent variable FMD.

RESULTS

Median [interquartile range] FMD decreased from 4.1% [2.8-6.3] to 3.2% [0.7-4.3] PML (P=0.02). At the multivariate analysis PML total cysteine (beta=-0.008, P=0.002) and glutathione (beta=0.21, P=0.005) were the only independent variables associated with FMD after methionine, adjusted for baseline FMD.

CONCLUSIONS

Elevated plasma total cysteine and decreased plasma total glutathione levels were associated with abnormal FMD PML. Cysteine and glutathione are stronger markers of endothelial dysfunction than clinical and all other biochemical variables explored.

Effect of Homocysteine Lowering by 5-Methyltetrahydrofolate on Redox Status in Hyperhomocysteinemia

The endothelial dysfunction induced by hyperhomocysteinemia can be reversed by 5-methyltetrahydrofolate (5-MTHF) via homocysteine (Hcy) lowering. An additive antioxidant action of 5-MTHF has been suggested to ameliorate endothelial dysfunction through increased nitric oxide production and superoxide radical scavenging, independent of Hcy lowering. The aim of the study was to assess whether 5-MTHF affects the redox state in hyperhomocysteinemia. We examined the effect of 3 months of oral 5-MTHF treatment (15 mg/day) on the redox pattern in 48 hyperhomocysteinemic subjects compared to 24 untreated hyperhomocysteinemic subjects. By analysis of variance with repeated measures in the 72 subjects, 5-MTHF markedly decreased plasma total Hcy (p-tHcy; P = 0.0001) and blood-total glutathione (GSH; b-tGSH; P = 0.002). By multivariate linear regression in the treated subjects, p-tHcy changes from baseline to 3 months (adjusted by baseline p-tHcy levels) correlated only with changes in reduced cysteinylglycine (P = 0.001). The effects of treatment on Hcy lowering and GSH metabolism were greater in medium than in moderate hyperhomocysteinemia. In conclusion, high-dose 5-MTHF treatment for 3 months ensures marked Hcy lowering to normal values even in subjects with high Hcy levels, and should be the treatment of choice in medium hyperhomocysteinemia. Furthermore, 5-MTHF shows a favorable interaction with GSH metabolism.

Elevated HDL Cholesterol is Functionally Ineffective in Cardiac Transplant Recipients: Evidence for Impaired Reverse Cholesterol Transport

BACKGROUND

Cardiac transplant recipients frequently have high plasma HDL levels but it is unclear whether these promote a cardioprotective profile.

METHODS

Parameters of reverse cholesterol transport and endothelial function were compared in 25 cardiac transplant recipients with low (<1.4 mmol/L; n=11) or high (>1.4 mmol/L; n=14) plasma levels of HDL and in a reference healthy group.

RESULTS

Patients with high HDL had lower levels of triglyceride and prebeta1-HDL and a higher proportion of large HDL particles. When normalized to apoA-I content, non-ABCA1-dependent cholesterol efflux from RAW 264.7 macrophage cells to plasma from high HDL patients was 33% lower when compared to plasma from patients with low HDL, whereas ABCA1-dependent cholesterol efflux was not impaired. Forearm vascular responses to acetylcholine and sodium nitroprusside were not influenced by HDL levels in these patients. Compared to a reference healthy group (n=26), cardiac transplant recipients had higher levels of triglyceride, lower levels of prebeta1-HDL and LCAT, and lower activities of cholesteryl ester transfer protein and phospholipid transfer protein.

CONCLUSIONS

Hyperalphalipoproteinaemia in cardiac transplant recipients is associated with the formation of partially dysfunctional HDL. We conclude that high levels of HDL may not confer cardioprotection in this group of patients.