Evaluation of dynamic thiol/disulphide homeostasis as a novel indicator of oxidative stress in maple syrup urine disease patients under treatment

Investigation of Thiol/Disulfide Homeostasis and Ischemia-Modified Albumin Levels in Children with Wilson Disease

BackgroundThe aim of the present study was to assess thiol/disulfide homeostasis (TDH) parameters and ischemia-modified albumin (IMA) levels in children with Wilson Disease (WD) and to compare them to healthy controls. Methods: Based on the inclusion and exclusion criteria, fifteen children with WD and twenty-nine healthy children were enrolled, and serum thiol/disulfide and IMA levels were compared between groups. Results: The mean values of native and total thiols were significantly lower in the WD group than in the control group. The mean value of disulfide was significantly higher in the WD group than in the control group. The mean percentages of disulfide/total thiol and native thiol/total thiol were higher in the WD group than in the control group. The IMA value was also higher in the WD group than in the control group. Conclusion: The present study demonstrating altered thiol/disulfide parameters indicates increased oxidative stress in children with WD.

Evaluation of dynamic thiol/disulfide homeostasis in hereditary tyrosinemia type 1 patients

BACKGROUND

Despite successful treatment with nitisinone, the pathophysiology of long-term complications, including hepatocellular carcinoma and mental decline in tyrosinemia type 1 patients, is still obscure. Oxidative stress may play a role in these complications. While increased fumarylacetoacetate and maleylacetoacetate cause oxidative stress in the liver, increased tyrosine causes oxidative stress in the brain. The aim of this study is to evaluate dynamic thiol/disulfide homeostasis as an indicator of oxidative stress in late-diagnosed tyrosinemia type 1 patients.

METHODS

Twenty-four late-diagnosed (age of diagnosis; 14.43 ± 26.35 months) tyrosinemia type 1 patients (19 under nitisinone treatment and 5 with liver transplantation) and 25 healthy subjects were enrolled in the study. Serum native thiol, total thiol, and disulfide levels were measured, and disulfide/native, disulfide/total, and native thiol/total thiol ratios were calculated from these values.

RESULTS

No significant difference was observed in native, total, and disulfide thiol levels between the groups and no increase in disulfide/native, disulfide/total, and native/total thiol ratios was detected, despite significantly higher plasma tyrosine levels in the nitisinone-treated group.

CONCLUSIONS

We suggest that providing sufficient metabolic control with good compliance to nitisinone treatment can help to prevent oxidative stress in late-diagnosed tyrosinemia type 1 patients.

IMPACT

Despite successful nitisinone (NTBC) treatment, the underlying mechanisms of long-term complications in hereditary tyrosinemia type 1 (HT1), including hepatocellular carcinoma and mental decline, are still obscure. Oxidative stress may play a role in these complications. Thiol/disulfide homeostasis, which is an indicator of oxidative stress, is not disturbed in hereditary tyrosinemia patients under NTBC treatment, despite higher plasma tyrosine levels and patients who had liver transplantation. This is the first study evaluating dynamic thiol/disulfide homeostasis as an indicator of oxidative stress in late-diagnosed HT1 patients.

Exposure to leucine induces oxidative stress in the brain of zebrafish

Maple Syrup Urine Disease (MSUD) is an autosomal recessive inherited disorder caused by a deficiency in the activity of the branched-chain alpha-ketoacid dehydrogenase complex leading to the accumulation of branched-chain amino acids (BCAA) leucine, isoleucine, and valine and their respective branched-chain α-ketoacids and corresponding hydroxy acids. Considering that Danio rerio, known as zebrafish, has been widely used as an experimental model in several research areas because it has favorable characteristics that complement other experimental models, this study aimed to evaluate oxidative stress parameters in zebrafish exposed to high levels of leucine (2 mM and 5 mM), in a model similar of MSUD. Twenty-four hours after exposure, the animals were euthanized, and the brain content dissected for analysis of oxidative stress parameters: thiobarbituric acid reactive substances (TBARS), 2',7'-dichlorofluorescein oxidation assay (DCF); content of sulfhydryl, and superoxide dismutase (SOD) and catalase (CAT) activities. Animals exposed to 2 mM and 5 mM leucine showed an increase in the measurement of TBARS and decreased sulfhydryl content. There were no significant changes in DCF oxidation. In addition, animals exposed to 2 mM and 5 mM leucine were found to have decreased SOD activity and increased CAT activity. Based on these results, exposure of zebrafish to high doses of leucine can act as a promising animal model for MSUD, providing a better understanding of the toxicity profile of leucine exposure and its use in future investigations and strategies related to the pathophysiology of MSUD.

Nuclear Factor Erythroid-2-Related Factor 2 Signaling in the Neuropathophysiology of Inherited Metabolic Disorders

Inherited metabolic disorders (IMDs) are rare genetic conditions that affect multiple organs, predominantly the central nervous system. Since treatment for a large number of IMDs is limited, there is an urgent need to find novel therapeutical targets. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a transcription factor that has a key role in controlling the intracellular redox environment by regulating the expression of antioxidant enzymes and several important genes related to redox homeostasis. Considering that oxidative stress along with antioxidant system alterations is a mechanism involved in the neuropathophysiology of many IMDs, this review focuses on the current knowledge about Nrf2 signaling dysregulation observed in this group of disorders characterized by neurological dysfunction. We review here Nrf2 signaling alterations observed in X-linked adrenoleukodystrophy, glutaric acidemia type I, hyperhomocysteinemia, and Friedreich’s ataxia. Additionally, beneficial effects of different Nrf2 activators are shown, identifying a promising target for treatment of patients with these disorders. We expect that this article stimulates research into the investigation of Nrf2 pathway involvement in IMDs and the use of potential pharmacological modulators of this transcription factor to counteract oxidative stress and exert neuroprotection.

Altered thiol/disulfide homeostasis and ischemia-modified albumin levels in children with irritable bowel syndrome

BACKGROUND

In this study, we assessed thiol/disulfide homeostasis (TDH) parameters and ischemia-modified albumin (IMA) levels in children with irritable bowel syndrome (IBS) compared with healthy children.

METHODS

Fifty-six children with IBS and 53 healthy children were included in the study after assessment of inclusion and exclusion criteria. Plasma thiol/disulfide and IMA levels were compared between children with and without IBS.

RESULTS

The mean values of native thiol, total thiol, and disulfide were 343.779 ± 138.654 μmol/L, 365.398 ± 140.148 μmol/L, and 23.190 ± 4.978 μmol/L, respectively, in the IBS group and 409.908 ± 69.288 μmol/L, 433.481 ± 76.891 μmol/L, and 20.090 ± 4.252 μmol/L, respectively, in the control group. Native thiol and total thiol values were significantly reduced in the IBS group compared with the control group. The mean IMA values were 0.835 ± 0.083 (g/L) and 0.778 ± 0.072 in the IBS and control groups, respectively. The IMA value was significantly increased in the IBS group.

CONCLUSION

Impaired thiol/disulfide homeostasis and increased IMA levels can be considered etiological factors in children with IBS.

Thiol-disulfide homeostasis: an integrated approach with biochemical and clinical aspects

Dynamic thiol-disulfide homeostasis (TDH) is a new area has begun to attract more scrutiny. Dynamic TDH is reversal of thiol oxidation in proteins and represents the status of thiols (-SH) and disulfides (-S-S-). Organic compounds containing the sulfhydryl group is called thiol, composed of sulfur and hydrogen atoms. Disulfides are the most important class of dynamic, redox responsive covalent bonds build in between two thiol groups. For many years, thiol levels were analyzed by several methods. During last years, measurements of disulfide levels have been analyzed by a novel automated method, developed by Erel and Neselioglu. In this method, addition to thiol (termed as native thiol) levels, disulfide levels were also measured and sum of native thiol and disulfide levels were termed as total thiol. Therefore, TDH was begun to be understood in organism. In healthy humans, TDH is maintained within a certain range. Dysregulated dynamic TDH has been implicated several disorders with unknown etiology. A growing body of evidence has demonstrated that the thiol-disulfide homeostasis is involved in variety diseases, such as diabetes mellitus, hypertension, nonsmall cell lung cancer, familial Mediterranean fever (FMF), inflammatory bowel diseases, occupational diseases, gestational diabetes mellitus and preeclampsia. These results may elucidate some pathogenic mechanism or may be a predictor indicating diagnostic clue, prognostic marker or therapeutic sign. In conclusion, protection of the thiol-disulfide homeostasis is of great importance for the human being. Evidence achieved so far has proposed that thiol-disulfide homeostasis is an important issue needs to elucidate wholly.

The effect of newly initiated exercise training on dynamic thiol / disulphide homeostasis in sedentary obese adults

We studied dynamic thiol/disulphide homeostasis, an indicator of oxidative stress, to investigate the effects of newly initiated exercise training on sedentary obese adults. Seventeen sedentary obese adults and 15 normal-weight controls were included in the sample for this study. The obese adults were given a physical exercise training program that lasted twelve weeks. Before and after the exercise training program, blood samples were collected, and serum thiol/disulphide parameters were measured by using a novel technique. Before the start of the exercise training, it was observed that thiol/disulphide homeostasis was impaired, and this impairment was positively correlated with body mass index in sedentary obese adults because of the higher reactive oxygen species production in adipose tissue. However, while the obese participants' body mass index significantly decreased, the thiol/disulphide homeostasis parameters in the obese adults did not change over time as calculated at the baseline and compared to the calculation after the twelve weeks of exercise training. Despite a decrease in body mass index that occurred after the twelve weeks of exercise training, there was a lack of improvement in the obesity-induced impairment of thiol/disulphide homeostasis, which suggests that a newly initiated exercise training program may lead to oxidative stress.

Oxidative stress among L-2-hydroxyglutaric aciduria disease patients: evaluation of dynamic thiol/disulfide homeostasis

L-2-hydroxyglutaric aciduria (L2HGA) is an autosomal recessive disorder that is caused by deficiency of 2-hydroxyglutarate dehydrogenase. Pathophysiology of brain damage is poorly understood. In recent years, it was proposed that oxidative stress was elevated and led to brain injury. Aim of this study is to evaluate thiol/disulphide homeostasis as an indicator of oxidative stress in L2HGA patients who have been receiving antioxidant treatment. Sixteen L2HGA patients and 16 healthy individuals were included in the study. All the L2HGA patients were regularly followed up and presented neurological dysfunction at different grades. Fourteen patients had been receiving antioxidant treatment. Serum native thiol (-SH), total thiol (-SH + -S-S-) and disulphide (-S-S) levels were measured. Disulphide/native thiol, disulphide/total thiol and native thiol/total thiol ratios were calculated from these values. No significant difference was observed in -SH, -SH + -S-S-, -S-S levels between two groups. In addition to that, no increase of disulphide/native thiol and disulphide/total thiol ratios was detected. Thiol/disulphide homeostasis parameters were also compared between patients who had been receiving and not receiving antioxidant therapy; and between different types of antioxidant therapy and the results did not point to any significant difference. This is the first study that evaluates dynamic thiol/disulphide homeostasis as an indicator of oxidative stress in L2HGA and it has one of the largest sample sizes among previous studies. In our study we suggest that antioxidant therapy should be effective in preventing oxidative stress in L2HGA patients, which has been reported in previous studies and should be a part of standard therapy.