Drug Repurposing in Rare Diseases: An Integrative Study of Drug Screening and Transcriptomic Analysis in Nephropathic Cystinosis.

Diagnosis and cure for rare diseases represent a great challenge for the scientific community who often comes up against the complexity and heterogeneity of clinical picture associated to a high cost and time-consuming drug development processes. Here we show a drug repurposing strategy applied to nephropathic cystinosis, a rare inherited disorder belonging to the lysosomal storage diseases. This approach consists in combining mechanism-based and cell-based screenings, coupled with an affordable computational analysis, which could result very useful to predict therapeutic responses at both molecular and system levels. Then, we identified potential drugs and metabolic pathways relevant for the pathophysiology of nephropathic cystinosis by comparing gene-expression signature of drugs that share common mechanisms of action or that involve similar pathways with the disease gene-expression signature achieved with RNA-seq.

Detection of iron deficiency in children with Down syndrome.

PURPOSE: Current American Academy of Pediatrics guidelines for children with Down syndrome (DS) recommend a complete blood count (CBC) at birth and hemoglobin annually to screen for iron deficiency (ID) and ID anemia (IDA) in low-risk children. We aimed to determine if macrocytosis masks the diagnosis of ID/IDA and to evaluate the utility of biochemical and red blood cell indices for detecting ID/IDA in DS. METHODS: We reviewed data from 856 individuals from five DS specialty clinics. Data included hemoglobin, mean corpuscular volume, red cell distribution width (RDW), percent transferrin saturation (TS), ferritin, and c-reactive protein. Receiver operating characteristic curves were calculated. RESULTS: Macrocytosis was found in 32% of the sample. If hemoglobin alone was used for screening, all individuals with IDA would have been identified, but ID would have been missed in all subjects. RDW had the highest discriminability of any single test for ID/IDA. The combination of RDW with ferritin or TS led to 100% sensitivity, and RDW combined with ferritin showed the highest discriminability for ID/IDA. CONCLUSION: We provide evidence to support that a CBC and ferritin be obtained routinely for children over 1 year old with DS rather than hemoglobin alone for detection of ID.

Intrinsic Bone Defects in Cystinotic Mice.

Cystinosis is a rare lysosomal storage disorder caused by loss-of-function mutations of the CTNS gene, encoding cystinosin, a symporter that mediates cystine efflux from lysosomes. Approximately 95% of patients with cystinosis display renal Fanconi syndrome, short stature, osteopenia, and rickets. In this study, we investigated whether the absence of cystinosin primarily affects bone remodeling activity, apart from the influences of the Fanconi syndrome on bone mineral metabolism. Using micro-computed tomography and histomorphometric and bone serum biomarker analysis, we evaluated the bone phenotype of 1-month-old Ctns-/- knockout (KO) male mice without tubulopathy. An in vitro study was performed to characterize the effects of cystinosin deficiency on osteoblasts and osteoclasts. Micro-computed tomography analysis showed a reduction of trabecular bone volume, bone mineral density, and number and thickness in KO mice compared with wild-type animals; histomorphometric analysis revealed a reduction of osteoblast and osteoclast parameters in tibiae of cystinotic mice. Decreased levels of serum procollagen type 1 amino-terminal propeptide and tartrate-resistant acid phosphatase in KO mice confirmed reduced bone remodeling activity. In vitro experiments showed an impairment of Ctns-/- osteoblasts and osteoclasts. In conclusion, cystinosin deficiency primarily affects bone cells, leading to a bone loss phenotype of KO mice, independent from renal failure.

Targeting oxidative stress improves disease outcomes in a rat model of acquired epilepsy.

Epilepsy therapy is based on antiseizure drugs that treat the symptom, seizures, rather than the disease and are ineffective in up to 30% of patients. There are no treatments for modifying the disease-preventing seizure onset, reducing severity or improving prognosis. Among the potential molecular targets for attaining these unmet therapeutic needs, we focused on oxidative stress since it is a pathophysiological process commonly occurring in experimental epileptogenesis and observed in human epilepsy. Using a rat model of acquired epilepsy induced by electrical status epilepticus, we show that oxidative stress occurs in both neurons and astrocytes during epileptogenesis, as assessed by measuring biochemical and histological markers. This evidence was validated in the hippocampus of humans who died following status epilepticus. Oxidative stress was reduced in animals undergoing epileptogenesis by a transient treatment with N-acetylcysteine and sulforaphane, which act to increase glutathione levels through complementary mechanisms. These antioxidant drugs are already used in humans for other therapeutic indications. This drug combination transiently administered for 2 weeks during epileptogenesis inhibited oxidative stress more efficiently than either drug alone. The drug combination significantly delayed the onset of epilepsy, blocked disease progression between 2 and 5 months post-status epilepticus and drastically reduced the frequency of spontaneous seizures measured at 5 months without modifying the average seizure duration or the incidence of epilepsy in animals. Treatment also decreased hippocampal neuron loss and rescued cognitive deficits. Oxidative stress during epileptogenesis was associated with de novo brain and blood generation of high mobility group box 1 (HMGB1), a neuroinflammatory molecule implicated in seizure mechanisms. Drug-induced reduction of oxidative stress prevented HMGB1 generation, thus highlighting a potential novel mechanism contributing to therapeutic effects. Our data show that targeting oxidative stress with clinically used drugs for a limited time window starting early after injury significantly improves long-term disease outcomes. This intervention may be considered for patients exposed to potential epileptogenic insults.

Glutathione transferase P silencing promotes neuronal differentiation of retinal R28 cells.

Glutathione transferases (GSTs) play an important role in retinal pathophysiology. Within this family, the GSTP isoform is known as an endogenous regulator of cell survival and proliferation pathways and of cellular responses to oxidative stress. In the present study we silenced GSTP in R28 cells, a retinal precursor cell line with markers of both glial and neuronal origin, and obtained stable clones which were viable and, unexpectedly, characterized by a more neuronal phenotype. The degree of neuronal differentiation was inversely correlated with GSTP residual expression levels. The clone with the lowest expression of GSTP showed metabolic reprogramming, a more favorable redox status and, despite its neuronal phenotype, a sensitivity to glutamate and 4-hydroxynonenal toxicity comparable to that of control cells. Altogether, our evidence shows that near full depletion of GSTP in retinal precursor cells, triggers neuronal differentiation and prosurvival metabolic changes.

Frataxin silencing alters microtubule stability in motor neurons: implications for Friedreich's ataxia.

To elucidate the pathogenesis of axonopathy in Friedreich's Ataxia (FRDA), a neurodegenerative disease characterized by axonal retraction, we analyzed the microtubule (MT) dynamics in an in vitro frataxin-silenced neuronal model (shFxn). A typical feature of MTs is their "dynamic instability", in which they undergo phases of growth (polymerization) and shrinkage (depolymerization). MTs play a fundamental role in the physiology of neurons and every perturbation of their dynamicity is highly detrimental for neuronal functions. The aim of this study is to determine whether MTs are S-glutathionylated in shFxn and if the glutathionylation triggers MT dysfunction. We hypothesize that oxidative stress, determined by high GSSG levels, induces axonal retraction by interfering with MT dynamics. We propose a mechanism of the axonopathy in FRDA where GSSG overload and MT de-polymerization are strictly interconnected. Indeed, using a frataxin-silenced neuronal model we show a significant reduction of neurites extension, a shift of tubulin toward the unpolymerized fraction and a consistent increase of glutathione bound to the cytoskeleton. The live cell imaging approach further reveals a significant decrease in MT growth lifetime due to frataxin silencing, which is consistent with the MT destabilization. The in vitro antioxidant treatments trigger the axonal re-growth and the increase in stable MTs in shFxn, thus contributing to identify new neuronal targets of oxidation in this disease and providing a novel approach for antioxidant therapies.

Targeting oxidative stress improves disease outcomes in a rat model of acquired epilepsy.

Epilepsy therapy is based on antiseizure drugs that treat the symptom, seizures, rather than the disease and are ineffective in up to 30% of patients. There are no treatments for modifying the disease-preventing seizure onset, reducing severity or improving prognosis. Among the potential molecular targets for attaining these unmet therapeutic needs, we focused on oxidative stress since it is a pathophysiological process commonly occurring in experimental epileptogenesis and observed in human epilepsy. Using a rat model of acquired epilepsy induced by electrical status epilepticus, we show that oxidative stress occurs in both neurons and astrocytes during epileptogenesis, as assessed by measuring biochemical and histological markers. This evidence was validated in the hippocampus of humans who died following status epilepticus. Oxidative stress was reduced in animals undergoing epileptogenesis by a transient treatment with N-acetylcysteine and sulforaphane, which act to increase glutathione levels through complementary mechanisms. These antioxidant drugs are already used in humans for other therapeutic indications. This drug combination transiently administered for 2 weeks during epileptogenesis inhibited oxidative stress more efficiently than either drug alone. The drug combination significantly delayed the onset of epilepsy, blocked disease progression between 2 and 5 months post-status epilepticus and drastically reduced the frequency of spontaneous seizures measured at 5 months without modifying the average seizure duration or the incidence of epilepsy in animals. Treatment also decreased hippocampal neuron loss and rescued cognitive deficits. Oxidative stress during epileptogenesis was associated with de novo brain and blood generation of disulfide high mobility group box 1 (HMGB1), a neuroinflammatory molecule implicated in seizure mechanisms. Drug-induced reduction of oxidative stress prevented disulfide HMGB1 generation, thus highlighting a potential novel mechanism contributing to therapeutic effects. Our data show that targeting oxidative stress with clinically used drugs for a limited time window starting early after injury significantly improves long-term disease outcomes. This intervention may be considered for patients exposed to potential epileptogenic insults.

Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells.

BACKGROUND: Nephropathic cystinosis is a lysosomal storage disease that is caused by mutations in the CTNS gene encoding a cystine/proton symporter cystinosin and an isoform cystinosin-LKG which is generated by an alternative splicing of exon 12. We have investigated the physiological role of the cystinosin-LKG that is widely expressed in epithelial tissues. METHODS: We have analyzed the intracellular localization and the function of the cystinosin-LKG conjugated with DsRed (cystinosin-LKG-RFP) in Madin-Darby canine kidney cells (MDCK II) and in proximal tubular epithelial cells carrying a deletion of the CTNS gene (cystinotic PTEC), respectively. RESULTS: Cystinosin-LKG-RFP colocalized with markers of lysosomes, late endosomes and was also expressed on the apical surface of polarized MDCK II cells. Moreover, immune-electron microscopy images of MDCK II cells overexpressing cystinosin-LKG-RFP showed stacked lamellar membranes inside perinuclear lysosomal structures. To study the role of LKG-isoform, we have investigated cystine accumulation and apoptosis that have been described in cystinotic cells. Cystinosin-LKG decreased cystine levels by approximately 10-fold similarly to cystinosin-RFP. The levels of TNFα- and actinomycin D-inducted apoptosis dropped in cystinotic cells expressing LKG-isoform. This effect was also similar to the main isoform. CONCLUSION: Our results suggest that cystinosin-LKG and cystinosin move similar functional activities in cells.

Nrf2-Inducers Counteract Neurodegeneration in Frataxin-Silenced Motor Neurons: Disclosing New Therapeutic Targets for Friedreich's Ataxia.

Oxidative stress is actively involved in Friedreich's Ataxia (FA), thus pharmacological targeting of the antioxidant machinery may have therapeutic value. Here, we analyzed the relevance of the antioxidant phase II response mediated by the transcription factor Nrf2 on frataxin-deficient cultured motor neurons and on fibroblasts of patients. The in vitro treatment of the potent Nrf2 activator sulforaphane increased Nrf2 protein levels and led to the upregulation of phase II antioxidant enzymes. The neuroprotective effects were accompanied by an increase in neurites' number and extension. Sulforaphane (SFN) is a natural compound of many diets and is now being used in clinical trials for other pathologies. Our results provide morphological and biochemical evidence to endorse a neuroprotective strategy that may have therapeutic relevance for FA. The findings of this work reinforce the crucial importance of Nrf2 in FA and provide a rationale for using Nrf2-inducers as pharmacological agents.

Activation of the transcription factor EB rescues lysosomal abnormalities in cystinotic kidney cells.

Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disease characterized by accumulation of cystine into lysosomes secondary to mutations in the cystine lysosomal transporter, cystinosin. The defect initially causes proximal tubular dysfunction (Fanconi syndrome) which in time progresses to end-stage renal disease. Cystinotic patients treated with the cystine-depleting agent, cysteamine, have improved life expectancy, delayed progression to chronic renal failure, but persistence of Fanconi syndrome. Here, we have investigated the role of the transcription factor EB (TFEB), a master regulator of the autophagy-lysosomal pathway, in conditionally immortalized proximal tubular epithelial cells derived from the urine of a healthy volunteer or a cystinotic patient. Lack of cystinosin reduced TFEB expression and induced TFEB nuclear translocation. Stimulation of endogenous TFEB activity by genistein, or overexpression of exogenous TFEB lowered cystine levels within 24 hours in cystinotic cells. Overexpression of TFEB also stimulated delayed endocytic cargo processing within 24 hours. Rescue of other abnormalities of the lysosomal compartment was observed but required prolonged expression of TFEB. These abnormalities could not be corrected with cysteamine. Thus, these data show that the consequences of cystinosin deficiency are not restricted to cystine accumulation and support the role of TFEB as a therapeutic target for the treatment of lysosomal storage diseases, in particular of cystinosis.

Altered mTOR signalling in nephropathic cystinosis.

Lysosomes play a central role in regulating autophagy via activation of mammalian target of rapamycin complex 1 (mTORC1). We examined mTORC1 signalling in the lysosomal storage disease nephropathic cystinosis (MIM 219800), in which accumulation of autophagy markers has been previously demonstrated. Cystinosis is caused by mutations in the lysosomal cystine transporter cystinosin and initially affects kidney proximal tubules causing renal Fanconi syndrome, followed by a gradual development of end-stage renal disease and extrarenal complications. Using proximal tubular kidney cells obtained from healthy donors and from cystinotic patients, we demonstrate that cystinosin deficiency is associated with a perturbed mTORC1 signalling, delayed reactivation of mTORC1 after starvation and abnormal lysosomal retention of mTOR during starvation. These effects could not be reversed by treatment with cystine-depleting drug cysteamine. Altered mTORC1 signalling can contribute to the development of proximal tubular dysfunction in cystinosis and points to new possibilities in therapeutic intervention through modulation of mTORC-dependent signalling cascades.

High concentrations of H2O2 trigger hypertrophic cascade and phosphatase and tensin homologue (PTEN) glutathionylation in H9c2 cardiomyocytes.

Cardiac hypertrophy occurs in response to different stimuli and is mainly characterized by an enlargement of cardiomyocyte size. During hypertrophy, cardiomyocytes undergo not only radical changes of the cellular architecture but also activation of signaling cascades that counteract the atrophy genes. Experimental studies highlighted that chronic low concentrations of H2O2, induce a hypertrophic phenotype, while higher levels of H2O2 promote apoptosis. In this study, we explored the early and long-term hypertrophic effects of high concentrations of H2O2 on H9c2 rat cardiomyocytes. We found that 2-h stimulation with 200µM H2O2 caused an early dramatic reduction of cell viability, accompanied, 5-days later, by increased cell size and up-regulation of atrial natriuretic peptide transcription. This hypertrophic phenotype is associated to increased Akt phosphorylation and a consequent reduction of the FOXO3a and atrogin-1 gene expression. Moreover, we observed that H2O2 caused the overexpression of miR-212/miR-132 cluster concomitantly to a down-regulation of PTEN transcript without changes in its protein expression. Noteworthy, we found that the treatment of cardiomyocytes with H2O2 further led to an increase of oxidized glutathione and glutathionylation of proteins, including PTEN. In conclusion, our results permit to reconstruct the molecular cascade triggering the cardiomyocyte hypertrophy upon high concentrations of H2O2.

Reverse-phase high-performance liquid chromatography for the simultaneous determination of sildenafil and N-desmethyl sildenafil in plasma of children.

Sildenafil is a selective inhibitor of cGMP-specific type 5 phosphodiesterase used for the treatment of pulmonary arterial hypertension (PAH) in the adults. In pediatrics, PAH treatment options include the off-label use of sildenafil. Sildenafil is metabolized in the liver by cytocrome P450 into its active metabolite, N-desmethyl sildenafil. The determination of plasma levels of sildenafil and N-desmethyl sildenafil could be useful for therapy optimization and pharmacokinetic studies. We have developed and validated a method for the quantification of sildenafil and its metabolite in plasma of children by rapid extraction, using high-performance liquid chromatography with ultraviolet detection. The calibration range was fitted at least square model (r2 ≥ 0.999), with an accuracy and an intra- and inter-day relative standard deviation <15% for both analytes. The mean recovery was 102.5% for sildenafil and 101.8% for N-desmethyl sildenafil. This simple method could be successfully used in children with PAH under treatment with sildenafil.

The proteome of cblC defect: in vivo elucidation of altered cellular pathways in humans.

Methylmalonic acidemia with homocystinuria, cobalamin deficiency type C (cblC) (MMACHC) is the most common inborn error of cobalamin metabolism. Despite a multidrug treatment, the long-term follow-up of early-onset patients is often unsatisfactory, with progression of neurological and ocular impairment. Here, the in-vivo proteome of control and MMACHC lymphocytes (obtained from patients under standard treatment with OHCbl, betaine, folate and L-carnitine) was quantitatively examined by two dimensional differential in-gel electrophoresis (2D-DIGE) and mass spectrometry. Twenty three proteins were found up-regulated and 38 proteins were down-regulated. Consistent with in vivo studies showing disturbance of glutathione metabolism, a deregulation in proteins involved in cellular detoxification, especially in glutathione metabolism was found. In addition, relevant changes were observed in the expression levels of proteins involved in intracellular trafficking and protein folding, energy metabolism, cytoskeleton organization and assembly. This study demonstrates relevant changes in the proteome profile of circulating lymphocytes isolated from treated cblC patients. Some results confirm previous observations in vivo on fibroblast, thus concluding that some dysregulation is ubiquitous. On the other hand, new findings could be tissue-specific. These observations expand our current understanding of the cblC disease and may ignite new research and therapeutic strategies to treat this disorder.

Influence of dialysis techniques and alternate vitamin supplementation on homocysteine levels in patients with known MTHFR genotypes.

BACKGROUND: Treatment with folic acid and vitamin B12 appears capable of reducing total plasma homocysteine levels (tHcy), but it is unknown whether vitamin B12 alone reduces tHcy values. In this study we investigate the effects of alternate vitamins supplementation on homocysteine levels in patients treated by diffusive and convective dialysis techniques. METHODS: 74 patients were randomized blindly into two groups of 37 subjects each. The first group was treated initially with vitamin B12 for 2 months and with folic acid for the following 2 months. The second group was treated initially with folic acid. A wash out period of 2 months followed the treatment in both groups. RESULTS: Total homocysteine levels decreased in both groups following the alternate vitamins therapy and dialysis, without significant difference between diffusive and convective techniques. Surprisingly, after the wash-out period, tHcy increased remarkably, regardless of the dialysis procedure used. At the end of the study, folate levels showed a higher reduction with haemodialysis compared to haemodiafiltration. In contrast, vitamin B12 levels showed a significant increase using diffusive haemodialysis, confirming a decisive role of membrane performance. CONCLUSIONS: In conclusion we show for the first time that, even if total homocysteine levels decreased in both dialysis procedures, the convective techniques demonstrate a superior capacity on the reduction of tHcy levels compared to the diffusive method. Moreover, the lower depletion of vitamin B12 by diffusive techniques could determine a higher reduction of folate levels, demonstrating the decisive role of the membrane performance in the treatment of this patients.

Implications for chronic toxicity of benzo[a]pyrene in sea bream cultured hepatocytes: Cytotoxicity, inflammation, and cancerogenesis.

Benzo[a]pyrene (B[a]P) is the most studied dangerous polycyclic aromatic hydrocarbon for its hepatotoxic, carcinogenic, mutagenic, teratogenic, and immunosuppressant effects, which can affect both wild and farmed marine fish through the trophic chain. This study investigated, for the first time, the chronic effects induced in vitro by B[a]P prolonged exposure on gilthead sea bream (Sparus aurata L.) hepatocytes, evaluating the cellular and nuclear latent damage. The purpose was to characterize the kind of B[a]P cyto- and genotoxic damage by morphological and immunocytochemical parameters applied in combination with the use of multiple assay endpoints. In light of our results, the short-term effects at higher B[a]P doses were linked to higher cytotoxicities and necrotic lysis, whereas a sustained inflammatory response at medium-low doses was perceived as a mitochondria-mediated apoptosis, both by surface and nuclear morphological changes. The strong immunoreactivity for the cleaved caspase-3 showed that the labeled cells committed suicide by apoptosis. B[a]P involvement on carcinogenesis comes from prolonged exposure at lower doses, establishing the connection between the escape from apoptosis and the selection of a tumoral phenotype. Cells colabeled with proliferating cell nuclear antigen/caspase-3 within the proliferative foci, were proliferating transformed oval stem cells, which escaped the suicide by apoptosis allowing cancer development. Finally, it was established that sea bream cultured hepatocytes are highly sensitive to chronic B[a]P exposure, as serious genotoxic effects were found even at the lowest doses.

Gender-related effects on urine L-cystine metastability.

Cystinuria is an autosomal recessive disease that causes L-cystine precipitation in urine and nephrolithiasis. Disease severity is highly variable; it is known, however, that cystinuria has a more severe course in males. The aim of this study was to compare L-cystine metastability in first-morning urine collected from 24 normal female and 24 normal male subjects. Samples were buffered at pH 5 and loaded with L-cystine (0.4 and 4 mM final concentration) to calculate the amount remaining in solution after overnight incubation at 4 °C; results were expressed as Z scores reflecting the L-cystine solubility in each sample. In addition, metabolomic analyses were performed to identify candidate compounds that influence L-cystine solubility. L-cystine solubility Z score was +0.44 ± 1.1 and -0.44 ± 0.70 in female and male samples, respectively (p < 0.001). Further analyses showed that the L-cystine solubility was independent from urine concentration but was significantly associated with low urinary excretion of inosine (p = 0.010), vanillylmandelic acid (VMA) (p = 0.015), adenosine (p = 0.029), and guanosine (p = 0.032). In vitro L-cystine precipitation assays confirmed that these molecules induce higher rates of L-cystine precipitation in comparison with their corresponding dideoxy molecules, used as controls. In silico computational and modeling analyses confirmed higher binding energy of these compounds. These data indicate that urinary excretion of nucleosides and VMA may represent important factors that modulate L-cystine solubility and may represent new targets for therapy in cystinuria.

Glutathione metabolism in cobalamin deficiency type C (cblC).

BACKGROUND: Methylmalonic aciduria with homocystinuria, cblC defect, is the most frequent disorder of vitamin B12 metabolism. CblC patients are commonly treated with a multidrug therapy to reduce metabolite accumulation and to increase deficient substrates. However the long-term outcome is often unsatisfactory especially in patients with early onset, with frequent progression of neurological and ocular impairment. Recent studies, have shown perturbation of cellular redox status in cblC. To evaluate the potential contribution of oxidative stress into the patophysiology of cblC defect, we have analyzed the in vivo glutathione metabolism in a large series of cblC deficient individuals. METHODS: Levels of different forms of glutathione were measured in lymphocytes obtained from 18 cblC patients and compared with age-matched controls. Furthermore, we also analyzed plasma cysteine and total homocysteine. RESULTS: We found an imbalance of glutathione metabolism in cblC patients with a significant decrease of total and reduced glutathione, along with a significant increase of different oxidized glutathione forms. CONCLUSIONS: These findings show a relevant in vivo disturbance of glutathione metabolism underlining the contribution of glutathione pool depletion to the redox imbalance in treated cblC patients. Our study may be helpful in addressing future research to better understanding the pathogenetic mechanism of the disease and in developing new therapeutic approaches, including the use of novel vitamin B12 derivatives.

Plasma levels of homocysteine and cysteine increased in pediatric NAFLD and strongly correlated with severity of liver damage.

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of metabolic abnormalities ranging from simple triglyceride accumulation in the hepatocytes to hepatic steatosis with inflammation, ballooning and fibrosis. It has been demonstrated that the pathogenesis of NAFLD involves increased oxidative stress, with consumption of the major cellular antioxidant, glutathione (GSH). Liver has a fundamental role in sulfur compound metabolism, although the data reported on plasma thiols status in NAFLD are conflicting. We recruited 63 NAFLD patients, and we analyzed all plasma thiols, such as homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CysGly) and GSH, by high-performance liquid chromatography (HPLC) with fluorescence detection. Hcy, Cys and CysGly plasma levels increased in NAFLD patients (p < 0.0001); whereas GSH levels were decreased in NAFLD patients when compared to controls (p < 0.0001). On the contrary, patients with steatohepatitis exhibited lower levels of Hcy and Cys than subjects without. Furthermore, a positive correlation was found between Hcy and Cys and the presence of fibrosis in children with NAFLD. Taken together, these data demonstrated a defective hepatic sulfur metabolism in children with NAFLD, and that high levels of Hcy and Cys probably correlates with a pattern of more severe histological liver damage, due to mechanisms that require further studies.