Effects of cysteamine on oxidative status in cerebral cortex of rats

Cysteamine-supplemented diet for cashmere goats: A potential strategy to inhibit rumen biohydrogenation and enhance plasma antioxidant capacity

Cysteamine (CS), as a feed supplement, can increase the level of growth hormone (GH) in the blood, promote animal growth. However, little attention has been paid to the effects of CS on the rumen microbiome and metabolic profile in cashmere goats. This study aimed to assess the effects of rumen microbiota, metabolites, and plasma antioxidative capacity induced by CS supplementation in cashmere goats. We selected 30 Inner Mongolia white cashmere goat ewes (aged 18 months), and randomly separate the goats into three groups (n = 10 per group) to experiment for 40 days. Oral 0 (control group, CON), 60 (low CS, LCS), or 120 mg/kg BW^-1 (high CS, HCS) coated CS hydrochloride every day. Using 16S and internal transcribed spacer (ITS) rRNA gene amplicon sequencing, we identified 12 bacterial and 3 fungal genera with significant changes among the groups, respectively. We found a significant increase in rumen NH₃-N and total volatile fatty acid (TVFA) concentrations in the LCS and HCS groups compared with the CON. With untargeted LC-MS/MS metabolomics, we screened 59 rumen differential metabolites. Among the screened metabolites, many unsaturated and saturated fatty acids increased and decreased with CS treatment, respectively. CS supplementation increased the levels of plasma total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), GH, and insulin-like growth factor-1(IGF-1). Spearman correlation analysis revealed that the abundance of U29-B03, Lactococcus, and Brochothrix were positively associated with the levels of δ2-THA, TVFA and antioxidant capacity. In conclusion, CS significantly affected rumen microbiota and fermentation parameters, and ultimately inhibited the biohydrogenation of rumen metabolites, enhanced plasma antioxidant capacity, and regulated some hormones of the GH-IGF-1 axis. This study provides an overall view into the CS application as a strategy to improve health production in cashmere goats.

Colorimetric determination of cysteamine based on the aggregation of polyvinylpyrrolidone-stabilized silver nanoparticles

A simple, colorimetric and visual method is described for the determination of cysteamine (CA) using polyvinylpyrrolidone-stabilized silver nanoparticles (PVP-AgNPs) as a colorimetric probe. The sensing method was based on the aggregation of PVP-AgNPs that led to the changes in the color and absorption profile of the probe. The aggregation of PVP-AgNPs in the presence of CA was evidenced by using transmission electron microscopy (TEM), zeta and dynamic light scattering (DLS) measurements. A distinct color transition could be observed with the naked eye from pale yellow color of PVP-AgNPs to purple. PVP-AgNPs probe showed an excellent selectivity towards CA versus other interfering biomolecules, cations and anions. Furthermore, the colorimetric probe had a linear response for CA from 0.1 to 1.0 μM concentration range with the limit of detection (LOD) of 4.9 nM. The prepared probe was successfully utilized for the determination of CA in blood serum as biological samples.

Transglutaminase 2 Induces Deficits in Social Behavior in Mice

Impairments in social behavior are highly implicated in many neuropsychiatric disorders. Recent studies indicate a role for endoplasmic reticulum (ER) stress in altering social behavior, but the underlying mechanism is not known. In the present study, we examined the role of transglutaminase 2 (TG2), a calcium-dependent enzyme known to be induced following ER stress, in social behavior in mice. ER stress induced by tunicamycin administration increased TG2 protein levels in the mouse prefrontal cortex (PFC). PFC-specific inhibition of TG2 attenuated ER stress-induced deficits in social behavior. Conversely, overexpression of TG2 in the PFC resulted in social behavior impairments in mice. In addition, systemic administration of cysteamine, a TG2 inhibitor, attenuated social behavior deficits. Our preliminary findings using postmortem human brain samples found increases in TG2 mRNA and protein levels in the middle frontal gyrus of subjects with autism spectrum disorder. These findings in mice and human postmortem brain samples identify changes in TG2 activity in the possible dysregulation of social behavior.

Cysteamine revisited: repair of arginine to cysteine mutations

Cysteamine is a small aminothiol endogenously derived from coenzyme A degradation. For some decades, synthetic cysteamine has been employed for the treatment of cystinosis, and new uses of the drug continue to emerge. In this review, we discuss the role of cysteamine in cellular and extracellular homeostasis and focus on the potential use of aminothiols to reconstitute the function of proteins harboring arginine (Arg) to cysteine (Cys) mutations, via repair of the Cys residue into a moiety that introduces an amino group, as seen in basic amino acid residues Lys and Arg. Cysteamine has been utilized in vitro and ex vivo in four different genetic disorders, and thus provides "proof of principle" that aminothiols can modify Cys residues. Other aminothiols such as mercaptoethylguanidine (MEG) with closer structural resemblance to the guanidinium moiety of Arg are under examination for their predicted enhanced capacity to reconstitute loss of function. Although the use of aminothiols holds clinical potential, more studies are required to refine specificity and treatment design. The efficacy of aminothiols to target proteins may vary substantially depending on their specific extracellular and intracellular locations. Redox potential, pH, and specific aminothiol abundance in each physiological compartment are expected to influence the reactivity and turnover of cysteamine and analogous drugs. Upcoming research will require the use of suitable cell and animal models featuring Arg to Cys mutations. Since, in general, Arg to Cys changes comprise about 8% of missense mutations, repair of this specific mutation may provide promising avenues for many genetic diseases.

Executive function in nephropathic cystinosis

OBJECTIVE

We studied executive function (EF) in children and adolescents with cystinosis.

BACKGROUND

Cystinosis is a genetic metabolic disorder in which the amino acid cystine accumulates in all organs of the body, including the brain. Previous research has shown that individuals with cystinosis have visuospatial deficits, but normal intelligence and intact verbal abilities. Better understanding of the behavioral phenotype associated with cystinosis could have important implications for treatment.

METHODS

Twenty-eight children with cystinosis and 24 control participants (age range 8 to 17 years) underwent selected Delis-Kaplan executive function system tests for neuropsychological assessment of EF, and the participants' parents completed the behavior rating inventory of executive function.

RESULTS

Participants with cystinosis performed significantly more poorly than controls on all Delis-Kaplan Executive Function System indices examined and on the behavior rating inventory of executive function metacognition index and global executive composite.

CONCLUSIONS

EF is an area of potential risk in cystinosis. Our data have implications not only for the function of affected children and adolescents in school and daily life, but also for disease management and treatment adherence. Our findings can aid in the design and implementation of interventions and lead to a greater understanding of brain-behavior relationships in cystinosis.

Pharmacokinetics of cysteamine bitartrate following intraduodenal delivery

Cysteamine is approved for the treatment of cystinosis and is being evaluated for Huntington's disease and non-alcoholic fatty liver disease. Little is known about the bioavailability and biodistribution of the drug. The aim was to determine plasma, cerebrospinal fluid (CSF), and tissue (liver, kidney, muscle) cysteamine levels following intraduodenal delivery of the drug in rats pretreated and naïve to cysteamine and to estimate the hepatic first-pass effect on cysteamine. Healthy male rats (n = 66) underwent intraduodenal and portal (PV) or jugular (JVC) venous catheterization. Half were pretreated with cysteamine, and half were naïve. Following intraduodenal cysteamine (20 mg/kg), serial blood samples were collected from the PV or the JVC. Animals were sacrificed at specific time points, and CSF and tissue were collected. Cysteamine levels were determined in plasma, CSF, and tissue. The Cmax was achieved in 5-10 min from PV and 5-22.5 min from JVC. The PV-Cmax (P = 0.08), PV-AUC0-t (P = 0.16), JVC-Cmax (P = 0.02) and JVC-AUC0-t (P = 0.03) were higher in naive than in pretreated animals. Plasma cysteamine levels returned to baseline in ≤120 min. The hepatic first-pass effect was estimated at 40%. Peak tissue and CSF cysteamine levels occurred ≤22.5 min, but returned to baseline levels ≤180 min. There was no difference in CSF and tissue cysteamine levels between naïve and pretreated groups, although cysteamine was more rapidly cleared in the pretreated group. Cysteamine is rapidly absorbed from the small intestine, undergoes significant hepatic first-pass metabolism, crosses the blood brain barrier, and is almost undetectable in plasma, CSF, and body tissues 2 h after ingestion. Sustained-release cysteamine may provide prolonged tissue exposure.

Cysteamine attenuates the decreases in TrkB protein levels and the anxiety/depression-like behaviors in mice induced by corticosterone treatment

OBJECTIVE

Stress and glucocorticoid hormones, which are released into the circulation following stressful experiences, have been shown to contribute significantly to the manifestation of anxiety-like behaviors observed in many neuropsychiatric disorders. Brain-derived neurotrophic factor (BDNF) signaling through its receptor TrkB plays an important role in stress-mediated changes in structural as well as functional neuroplasticity. Studies designed to elucidate the mechanisms whereby TrkB signaling is regulated in chronic stress might provide valuable information for the development of new therapeutic strategies for several stress-related psychiatric disorders.

MATERIALS AND METHODS

We examined the potential of cysteamine, a neuroprotective compound to attenuate anxiety and depression like behaviors in a mouse model of anxiety/depression induced by chronic corticosterone exposure.

RESULTS

Cysteamine administration (150 mg/kg/day, through drinking water) for 21 days significantly ameliorated chronic corticosterone-induced decreases in TrkB protein levels in frontal cortex and hippocampus. Furthermore, cysteamine treatment reversed the anxiety and depression like behavioral abnormalities induced by chronic corticosterone treatment. Finally, mice deficient in TrkB, showed a reduced response to cysteamine in behavioral tests, suggesting that TrkB signaling plays an important role in the antidepressant effects of cysteamine.

CONCLUSIONS

The animal studies described here highlight the potential use of cysteamine as a novel therapeutic strategy for glucocorticoid-related symptoms of psychiatric disorders.

Enteric-coated cysteamine for the treatment of paediatric non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common cause of liver disease in children. Hepatic fat accumulation and oxidative stress contribute to its pathogenesis. Cysteamine bitartrate readily traverses cellular membranes and is a potent antioxidant.

AIM

To evaluate the safety and efficacy of enteric-coated (EC) cysteamine in children with NAFLD.

METHOD

Children, aged ≥10 y, meeting screening criteria with biopsy-proven NAFLD and serum ALT ≥60 IU/L, received twice-daily EC-cysteamine for 24 weeks. Monthly ALT, AST, body mass index (BMI) and gastrointestinal symptom scores were measured. Subjects with >50% reduction or normalisation of ALT achieved the primary endpoint.

RESULTS

Of the 13 children enrolled (mean age 14.0 years), 11 completed EC-cysteamine therapy (mean dose 15.2 mg/kg/day) and were included in the final analysis. For these 11 subjects, the mean ALT levels at baseline and 24 weeks were 120.2 and 55 IU/L respectively (P = 0.002), and the AST levels were 60 and 36 IU/L respectively (P = 0.007). The primary endpoint was reached in 7 and normalisation (≤40 IU/L) of ALT in 5. After 24 week therapy, mean adiponectin levels increased (P = 0.009) and CK-18 fragment levels decreased (P = 0.013), insulin levels remained unchanged (P = 0.99). Mean leptin levels were decreased in responders (P = 0.044). Mean BMI was 34.5 at baseline and 34.2 kg/m(2) after treatment (P = 0.35). Mean symptom scores at baseline (1.1) and at 24 weeks (0.7) were similar. No major adverse events were reported.

CONCLUSIONS

Enteric-coated cysteamine reduces ALT and AST levels in children with NAFLD without reduction in body mass index. Further studies will evaluate optimal cysteamine therapeutic dose and effect on liver histology in NAFLD (Clinicaltrials.gov protocol ID: 07-1699).

Developmental changes in cerebral white matter microstructure in a disorder of lysosomal storage

The goal of this work was to study white matter (WM) integrity in children with cystinosis, a rare lysosomal storage disorder resulting in cystine accumulation in peripheral and central nervous system tissue. Based on previous reports of cystine crystal formation in myelin precursors as well as evidence for specific cognitive deficits in visuospatial functioning, diffusion tensor imaging (DTI) was applied to 24 children with cystinosis (age 3-7 years) and to 24 typically developing age-matched controls. Scalar diffusion indices, fractional anisotropy (FA) and mean diffusivity (MD), were examined in manually defined regions of interest within the parietal and inferior temporal lobes. Diffusion indices were correlated with performance on measures of visuospatial cognition and with white blood cell cystine levels. Bilaterally decreased FA and increased MD were evident in the inferior and superior parietal lobules in children with cystinosis, with comparable FA and MD to controls in inferior temporal WM, and implicate a dissociation of the dorsal and ventral visual pathways. In older cystinosis children (age>5), diminutions in visuospatial performance were associated with reduced FA in the right inferior parietal lobule. In addition, increased MD was found in the presence of high cystine levels in all children with cystinosis. This study provides new information that the average diffusion properties in children with cystinosis deviate from typically developing children. Findings suggest the presence of early microstructural WM changes in addition to a secondary effect of cystine accumulation. These alterations may impact the development of efficient fiber networks important for visuospatial cognition.