Plasma and low-density lipoprotein lipid peroxidation in cyclosporine A-treated children after liver transplant

Gingival Crevicular Fluid and Plasma Levels of Transglutaminase-2 and Oxidative Stress Markers in Cyclosporin A-Induced Gingival Overgrowth

BACKGROUND

Transglutaminase (TGM)-2 has been shown to contribute to fibrosis by extracellular matrix accumulation in some organs and is activated by intracellular reactive oxygen species. The aim of this study is to investigate levels of gingival crevicular fluid (GCF) and plasma TGM-2 and oxidative stress markers (OSMs) in cyclosporin A (CsA)-induced gingival overgrowth (GO).

METHODS

The study enrolled 20 healthy (H) individuals; 20 patients with gingivitis (G); 20 CsA-medicated patients with GO (CsA GO+); and 20 CsA-medicated patients without GO (CsA GO-). GCF and plasma levels of TGM-2 were analyzed by enzyme-linked immunosorbent assay. Spectrofluorometry was used to analyze thiobarbituric acid reactive substance (TBARS); ferric-reducing antioxidant power (FRAP); total oxidant status (TOS); and total antioxidant capacity (TAC).

RESULTS

GCF TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.001) groups. GCF TBARS level was elevated in CsA GO+ compared with other groups (CsA GO- group: P = 0.003; G group: P <0.001; and H group: P <0.001) and was higher in CsA GO- than in H (P = 0.048). GCF FRAP level was lower in CsA GO- than in H (P = 0.04). Both CsA GO+ and CsA GO- groups had lower GCF TOS levels than H (P <0.001 and P = 0.002) and G (P = 0.003 and P = 0.04). GCF TAC was higher in CsA GO+ than in H (P = 0.02). Plasma TGM-2 level was elevated in CsA GO+ compared with G (P = 0.048) and H (P = 0.002). Plasma FRAP level was higher in H and CsA GO- than in CsA GO+ (P = 0.008 and P = 0.02).

CONCLUSIONS

CsA use significantly alters GCF and plasma levels of TGM-2 and OSMs. TGM-2 may contribute to CsA-induced GO in CsA-treated patients by changing GCF and plasma levels of OSMs. Further studies are needed to prove causality and its direction.

Lipid, Carbohydrate Metabolism, and Antioxidant Status in Children After Liver Transplantation

Organ transplantation is a risk factor for atherogenesis that may be related to immunosuppressive therapy. Increased free radical generation may even aggravate atherogenesis. The aim of the study was to assess lipid metabolism in relation to risk factors for atherogenesis as well as carbohydrate metabolism and antioxidant status among children after liver transplantation. We studied 35 children at 3 to 5 years after liver transplant in whom the following parameters were assessed: total cholesterol; triglyceride; high-density lipoprotein cholesterol; low-density lipoprotein cholesterol (LDL-C); very low-density lipoprotein cholesterol; apolipoproteins B, AI, E, lipoprotein (a); vitamin E; glutathione; glucose; insulin; and glutathione peroxidase activity. Three subgroups of patients were assessed according to the immunosuppressive therapy: cyclosporine (CsA), tacrolimus (Tac), or mycophenolate mofetil (MMF) in combination with low-dose CsA or Tac. We observed differences among the subgroups only in total cholesterol (CsA: 131.6 to 285.6; Tac: 144.0 to 181.61; MMF: 132.1 to 181.2) and LDL-C (CsA: 79.4 to 126.9; Tac: 42.2 to 118.8; MMF: 74.2 to 117.3). Lipid metabolism was not significantly disturbed among children after liver transplantation, an observation that does not point to a high risk of atherogenesis. CsA seems to have the strongest untoward effect on cholesterol metabolism. Decreased GSH concentration after liver transplantation may be related to slightly impaired liver function, but GPx activity and vitamin E concentrations remained normal.

Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences

Organ transplant recipients develop pronounced cardiovascular disease, and decreased antioxidant capacity in plasma and erythrocytes is associated with the pathogenesis of this disease. These experiments tested the hypothesis that the immunosuppressant cyclosporine A (CsA) alters erythrocyte redox balance and reduces plasma antioxidant capacity. Female Sprague-Dawley rats were randomly assigned to a control or CsA treated group. Treatment animals received 25 mg/kg/day of CsA via intraperitoneal injection for 18 days. Control rats were injected with the same volume of the vehicle. Three hours after the final CsA injection, rats were exsanguinated and plasma analysed for total antioxidant status (TAS), alpha-tocopherol, malondialdehyde (MDA), and creatinine. Erythrocytes were analysed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities, alpha-tocopherol, and MDA. CsA administration resulted in a significant (P < 0.05) decrease in plasma TAS and significant increases (P < 0.05) in plasma creatinine and MDA. Erythrocyte CAT was significantly (P < 0.05) increased in CsA treated rats compared to controls. There were no significant differences (P > 0.05) in erythrocyte SOD, GPX, G6PD, alpha-tocopherol or MDA between groups. In summary, CsA alters erythrocyte antioxidant defence and decreases plasma total antioxidant capacity.

Assessment of oxidative stress in the early posttransplant period: comparison of cyclosporine A and tacrolimus-based regimens

BACKGROUND

Oxidative stress is one of the leading causes of cardiovascular morbidity and mortality in chronic kidney disease. Although it is clear that many metabolic abnormalities improve, the effects of kidney transplantation on oxidative state are obscure.

METHODS

Twenty-three kidney transplant patients were included in the study. Eleven patients (mean age 27.9+/- 9.1 years) were treated with cyclosporine A (CsA) whereas 12 patients (mean age 22.4 +/- 3.4 years) were treated with tacrolimus. Twenty-three healthy subjects served as controls. None of the patients or controls suffered from diabetes mellitus or an acute infection at the time of the study. Plasma malondialdehyde (MDA), plasma selenium (Se), erythrocyte glutathione peroxidase (GSH-Px), erythrocyte superoxide dismutase (SOD), erythrocyte Zn (EZn), and erythrocyte Cu (ECu) levels were studied before and in the 1st, 3rd, 7th, 14th and 28th days after the transplantation.

RESULTS

The GSH-Px, SOD, ECu, EZn and selenium levels were lower and MDA levels were higher in patients than controls before transplantation (p < 0.001 for all). MDA levels decreased and SOD, GSH-Px, ECu, EZn levels increased in parallel to the decrement of serum creatinine levels following the renal transplantation. No difference was found among the patients regarding the treatment regime.

CONCLUSION

The study data suggest that the improvement in oxidative state parameters begins at the first day of renal transplantation and continues at the 28th posttransplant day in living donor transplantations.

Cyclosporine A-induced reduction of bile salt synthesis associated with increased plasma lipids in children after liver transplantation

Hyperlipidemia is a common side effect of cyclosporine A (CsA) after solid organ transplantation. CsA also markedly reduces the synthesis rate of bile salts in rats and can inhibit biliary bile salt secretion. It is not known, however, whether CsA inhibits the synthesis of bile salts in humans, and whether the hyperlipidemic effects of CsA are related to bile salt metabolism. Our objective was to assess the effects of CsA on the synthesis rate of bile salts and on plasma triglycerides and cholesterol levels in pediatric liver transplant patients. Before and after discontinuation of CsA treatment after liver transplantation, synthesis rate and pool size of the primary bile salts cholate and chenodeoxycholate were determined using a stable isotope dilution technique and related to plasma lipids. In 6 children (age: 3-16 years) CsA treatment was discontinued at 2 years (median 2.3 years) after liver transplantation. Discontinuation of CsA increased synthesis rate of chenodeoxycholate (+38%, P <.001) and cholate (+21%, P <.05) and the pool size of chenodeoxycholate (+54%, P <.001). Discontinuation of CsA decreased plasma levels of cholesterol (-18%, P <.05) and triglycerides (-23%, P <.05). Bile salt synthesis rate appeared to be inversely correlated with plasma cholesterol (Spearman rank correlation coefficient [r(s)] = -0.82, P <.01) and plasma triglyceride levels (r(s) = -0.62, P <.05). In conclusion, CsA inhibits bile salt synthesis and increases plasma concentration of cholesterol and triglycerides in pediatric liver transplant patients. Suppression of bile salt synthesis by long-term CsA treatment may contribute to hyperlipidemia and thus to increased risk for cardiovascular disease.

Oxidative stress in childhood—in health and disease states

The accumulated information concerning the involvement of reactive oxygen species in many clinical disorders and disease states has led to the potential for intervention with antioxidants in these cases. There are currently numerous clinical trials involving administration of antioxidants in a variety of conditions such as coronary heart disease, cataract, cancer and neurodegenerative diseases. At the same time therapeutic trials aimed at preventing and delaying the aging process are also under investigation. Numerous disorders, in childhood, have also been linked to oxidative damage. The aim of this review is to provide an overview of oxidative stress, its mechanisms, targets and damage incurred, as pertaining specifically to clinical disorders during childhood. The defense mechanisms against oxidation; the enzymatic antioxidants and low molecular weight antioxidants are defined and a number of methods commonly used for evaluation of oxidative stress (methods for measurement of lipid and protein oxidation end products and methods for measurement of antioxidant defense capacity) described. Specific diseases related to oxidative stress in infancy and childhood are reviewed and the possible effect of nutritional intake on oxidative stress in the healthy child discussed. Other issues addressed include the ability of oxidative stress, as measured in plasma to reflect intratissue oxidation, the need for a simple laboratory method for characterization of an oxidative stress 'profile', the proposed role of oxidative stress in biological processes pertaining to growth and maturation and possible implications of unrestricted antioxidant supplementation.

Markers of oxidative stress in cyclosporine-treated and tacrolimus-treated children after liver transplantation

Oxidative stress is presumed to have a major role in cyclosporine A (CsA)- and tacrolimus-induced tissue toxicity. The present study was performed to elucidate the degree of oxidative stress after liver transplantation in CsA- and tacrolimus-treated patients. Twenty-three patients (14 patients, CsA; 9 patients, tacrolimus) aged 2.5 to 18 years (mean, 9.8 years) who had undergone liver transplantation 1.5 to 12 years (mean, 5.4 years) before were studied. Eighteen healthy children aged 2 to 16.5 years (mean, 9.4 years) served as a control group. The following parameters were assessed: plasma lipoprotein levels; plasma carbonyl levels, as markers of oxidative damage to proteins; total plasma oxidizability, which evaluates plasma antioxidant capacity (lag phase) and lipoprotein susceptibility to oxidation; and plasma antioxidant capacity by cyclic voltammetry (CV), which measures antioxidant capacity stemming from hydrophilic low-molecular-weight antioxidant components. Carbonyl levels and rates of plasma oxidation did not differ between groups. The lag phase of plasma oxidation was significantly longer in CsA-treated children compared with tacrolimus-treated children or controls (mean, 54.4 +/- 4.8 [SE] v 40.2 +/- 2.2 v 46.5 +/- 2.8 minutes, respectively; P < 0.05). Antioxidant capacity, assessed by CV, did not differ among CsA-treated patients, tacrolimus-treated patients, and healthy controls. Plasma alpha-tocopherol and beta-carotene levels did not differ between CsA-treated and tacrolimus-treated patients. In children post-liver transplantation, oxidative damage assessed by markers of lipid and protein oxidation is not increased, and plasma antioxidant capacity is not diminished.

Reduction of free radical activity in amyloid deposits following liver transplantation for familial amyloidotic polyneuropathy

OBJECTIVES

Liver transplantation halt the progress of familial amyloidotic polyneuropathy (FAP). Oxidative stress has been implicated in amyloid toxicity and formation. The objective of this study was to establish whether markers for oxidant stress and antioxidant capacity change following liver transplantation in patients with FAP.

DESIGN

Morphometric and biochemical study.

SETTING

Tertiary referral centre.

SUBJECTS

Duodenal biopsy samples from 16 patients, taken before and after liver transplantation were used for morphometry. Serum samples from 14 patients, seven of whom had received transplants, were analysed regarding antioxidant capacity.

INTERVENTION

Liver transplantation.

MAIN OUTCOME MEASURES

Immunohistochemistry was used to stain for the lipid peroxidation product 4-hydroxynonenal (HNE), and Congo red staining was used for amyloid detection. Positive areas were quantified by point counting. Total antioxidant capacity (TAC) was measured with a colourimetric assay.

RESULTS

In tissue, a decrease of HNE was noted after liver transplantation, whereas no significant changes were detected for amyloid deposits. No difference between transplanted and not transplanted patients was noted for total antioxidant capacity measured in serum.

CONCLUSION

To our knowledge, this is the first description of a reduction of markers for free radical activity after cessation of amyloid formation. The findings implicate that amyloid formation in transthyretin (TTR) amyloidosis generates oxidative stress, whereas amyloid deposits as such are less toxic to sourrounding tissues.

Cyclosporine directly causes oxidative stress and promotes Epstein-Barr virus transformation of human B cells

BACKGROUND

We have previously shown that oxidative stress alone can promote transformation of human B cells infected with Epstein-Barr virus (EBV) in vitro, an accepted model mimicking posttransplant lymphoproliferative disorders (PTLDs). Our laboratory has investigated the direct effects of cyclosporine A (CyA) as an oxidant promoting B-cell transformation and we have proposed that CyA directly promotes B-cell transformation and that this effect can be blocked by antioxidants.

METHODS

Human splenocytes were prepared by centrifugation and plating technique to provide a greater than 80% pure preparation of B cells that was used for the direct oxidative stress experiments. These cells were cocultured with CyA (500 ng/ml) and hydrogen peroxide (H(2)O(2), 0.15 mM) with or without antioxidant vitamin E (40 microM). Oxidative stress was evaluated by using a commercial lipid hydroperoxide (LPO) assay kit. In another set of three separate experiments, human B lymphocytes infected with EBV were cultured with CyA (500 ng/ml), H(2)O(2) (0.15 mM), and vitamin E (40 microM). B-Cell transformation by EBV was evaluated by counting colony number and [(3)H]-thymidine incorporation.

RESULTS

At therapeutic concentrations, CyA (500 ng/mL) had an oxidative effect on human splenocytes in vitro, similar to the effect of H(2)O(2) (90 and 97% increases, respectively in LPO production over control P < 0.005), which was abrogated by the addition of vitamin E. Similarly, both CyA and H(2)O(2) promoted transformation of B cells infected with EBV(75 and 108% increases respectively in colony counts over control, P < 0.005). This effect was also blocked by vitamin E.

CONCLUSIONS

Both CyA and H(2)O(2) have a direct oxidative effect on human B cells and cause promotion of EBV-induced transformation of B cells. These effects are blocked by the antioxidant vitamin E. These findings may have future therapeutic implications for PTLDs.