No abstract

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of α-galactosidase A that leads to accumulation of the enzyme substrates, mainly globotriaosylceramide (Gb3), in body fluids and lysosomes of many cell types. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there is no in vivo study about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 levels in Fabry patients under treatment with enzyme replacement therapy (ERT) and finally to establish a possible relation between them. We analyzed urine and blood samples of patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by reduced glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we found that plasma levels of malondialdehyde (MDA) and protein carbonyl groups and di-tyrosine (di-Tyr) in urine were increased in patients. The pro-inflammatory cytokines IL-6 and TNF-α were also increased in patients. Urinary Gb3 levels were positively correlated with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 levels were directly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that pro-inflammatory and pro-oxidant states occur, are correlated and seem to be induced by Gb3 in Fabry patients.

Phenylketonuria (PKU) is an inborn error of amino acid metabolism caused by severe deficiency of phenylalanine hydroxylase activity, leading to the accumulation of phenylalanine and its metabolites in blood and tissues of affected patients. Phenylketonuric patients present as the major clinical feature mental retardation, whose pathomechanisms are poorly understood. In recent years, mounting evidence has emerged indicating that oxidative stress is possibly involved in the pathology of PKU. This article addresses some of the recent developments obtained from animal studies and from phenylketonuric patients indicating that oxidative stress may represent an important element in the pathophysiology of PKU. Several studies have shown that enzymatic and non-enzymatic antioxidant defenses are decreased in plasma and erythrocytes of PKU patients, which may be due to an increased free radical generation or secondary to the deprivation of micronutrients which are essential for these defenses. Indeed, markers of lipid, protein, and DNA oxidative damage have been reported in PKU patients, implying that reactive species production is increased in this disorder. A considerable set of data from in vitro and in vivo animal studies have shown that phenylalanine and/or its metabolites elicit reactive species in brain rodent. These findings point to a disruption of pro-oxidant/antioxidant balance in PKU. Considering that the brain is particularly vulnerable to oxidative attack, it is presumed that the administration of appropriate antioxidants as adjuvant agents, in addition to the usual treatment based on restricted diets or supplementation of tetrahydrobiopterin, may represent another step in the prevention of the neurological damage in PKU.

Propionic (PA) and methylmalonic (MMA) acidurias are inherited disorders caused by deficiency of propionyl-CoA carboxylase and methylmalonyl-CoA mutase, respectively. Affected patients present acute metabolic crises in the neonatal period and long-term neurological deficits. Treatments of these diseases include a protein restricted diet and L: -carnitine supplementation. L: -Carnitine is widely used in the therapy of these diseases to prevent secondary L: -carnitine deficiency and promote detoxification, and several recent in vitro and in vivo studies have reported antioxidant and antiperoxidative effects of this compound. In this study, we evaluated the oxidative stress parameters, isoprostane and di-tyrosine levels, and the antioxidant capacity, in urine from patients with PA and MMA at the diagnosis, and during treatment with L: -carnitine and protein-restricted diet. We verified a significant increase of isoprostanes and di-tyrosine, as well as a significant reduction of the antioxidant capacity in urine from these patients at diagnosis, as compared to controls. Furthermore, treated patients presented a marked reduction of isoprostanes and di-tyrosine levels in relation to untreated patients. In addition, patients with higher levels of protein and lipid oxidative damage, determined by di-tyrosine and isoprostanes levels, also presented lower urinary concentrations of total and free L: -carnitine. In conclusion, the present results indicate that treatment with low protein diet and L: -carnitine significantly reduces urinary biomarkers of protein and lipid oxidative damage in patients with disorders of propionate metabolism and that L: -carnitine supplementation may be specially involved in this protection.

It is well established that the involvement of reactive species in the pathophysiology of several neurological diseases, including phenylketonuria (PKU), a metabolic genetic disorder biochemically characterized by elevated levels of phenylalanine (Phe). In previous studies, we verified that PKU patients (treated with a protein-restricted diet supplemented with a special formula not containing L-carnitine and selenium) presented high lipid and protein oxidative damage as well as a reduction of antioxidants when compared to the healthy individuals. Our goal in the present study was to evaluate the effect of Phe-restricted diet supplemented with L-carnitine and selenium, two well-known antioxidant compounds, on oxidative damage in PKU patients. We investigated various oxidative stress parameters in blood of 18 treated PKU patients before and after 6 months of supplementation with a special formula containing L-carnitine and selenium. It was verified that treatment with L-carnitine and selenium was capable of reverting the lipid peroxidation, measured by thiobarbituric acid-reactive species, and the protein oxidative damage, measured by sulfhydryl oxidation, to the levels of controls. Additionally, the reduced activity of glutathione peroxidase was normalized by the antioxidant supplementation. It was also verified a significant inverse correlation between lipid peroxidation and L-carnitine blood levels as well as a significant positive correlation between glutathione peroxidase activity and blood selenium concentration. In conclusion, our results suggest that supplementation of L-carnitine and selenium is important for PKU patients since it could help to correct the oxidative stress process which possibly contributes, at least in part, to the neurological symptoms found in phenylketonuric patients.

Oxidative stress has been proposed as an important pathophysiologic feature of various inborn errors of metabolism, including phenylketonuria (PKU). Considering that there are few studies relating oxidative stress and inflammation directly in PKU disease, the aim of this study was to evaluate and correlate oxidative damage to biomolecules, antioxidant defenses, pro-inflammatory cytokines, phenylalanine (Phe) and its metabolites (phenyllactic acid--PLA and phenylacetic acid--PAA) levels in urine and plasma from patients with PKU under dietary treatment. We observed a marked increase of isoprostanes, which is a lipid peroxidation biomarker, in urine from these treated patients. Next, we demonstrated that protein oxidative damage, measured by di-tyrosine formation, was significantly increased in urine from PKU treated patients and that decreased urinary antioxidant capacity was also observed. Our findings concerning to the inflammatory cytokines interleukin-6 and interleukin-1β, both significantly increased in these patients, provide evidence that the pro-inflammatory state occurs. Besides, interleukin-1β was positively correlated with isoprostanes. We observed a negative correlation between interleukin-6 and interleukin-10, an anti-inflammatory cytokine. Di-tyrosine was positively correlated with Phe, which indicates oxidative damage to proteins, as well as with PAA. These findings may suggest that the protein damage may be induced by Phe and its metabolite PAA in PKU. Our results indicate that pro-oxidant and pro-inflammatory states occur and are, in part, correlated and protein oxidation seems to be induced by Phe and PPA in PKU patients.

No abstract

Maple syrup urine disease (MSUD) is a metabolic disease caused by a deficiency in the branched-chain α-keto acid dehydrogenase complex, leading to the accumulation of branched-chain keto acids and their corresponding branched-chain amino acids (BCAA) in patients. Treatment involves protein-restricted diet and the supplementation with a specific formula containing essential amino acids (except BCAA) and micronutrients, in order to avoid the appearance of neurological symptoms. Although the accumulation of toxic metabolites is associated to appearance of symptoms, the mechanisms underlying the brain damage in MSUD remain unclear, and new evidence has emerged indicating that oxidative stress contributes to this damage. In this context, this review addresses some of the recent findings obtained from cells lines, animal studies, and from patients indicating that oxidative stress is an important determinant of the pathophysiology of MSUD. Recent works have shown that the metabolites accumulated in the disease induce morphological alterations in C6 glioma cells through nitrogen reactive species generation. In addition, several works demonstrated that the levels of important antioxidants decrease in animal models and also in MSUD patients (what have been attributed to protein-restricted diets). Also, markers of lipid, protein, and DNA oxidative damage have been reported in MSUD, probably secondary to the high production of free radicals. Considering these findings, it is well-established that oxidative stress contributes to brain damage in MSUD, and this review offers new perspectives for the prevention of the neurological damage in MSUD, which may include the use of appropriate antioxidants as a novel adjuvant therapy for patients.