Cysteamine hydrochloride affects ocular development and triggers associated inflammation in zebrafish

The increasing use of cosmetics has raised widespread concerns regarding their ingredients. Cysteamine hydrochloride (CSH) is a newly identified allergenic component in cosmetics, and therefore its potential toxicity needs further elucidation. Here, we investigated the in vivo toxicity of CSH during ocular development utilizing a zebrafish model. CSH exposure was linked to smaller eyes, increased vasculature of the fundus and decreased vessel diameter in zebrafish larvae. Moreover, CSH exposure accelerated the process of vascular sprouting and enhanced the proliferation of ocular vascular endothelial cells. Diminished behavior in response to visual stimuli and ocular structural damage in zebrafish larvae after CSH treatment were confirmed by analysis of the photo-visual motor response and pathological examination, respectively. Through transcriptional assays, transgenic fluorescence photography and molecular docking analysis, we determined that CSH inhibited Notch receptor transcription, leading to an aberrant proliferation of ocular vascular endothelial cells mediated by Vegf signaling activation. This process disrupted ocular homeostasis, and induced an inflammatory response with neutrophil accumulation, in addition to the generation of high levels of reactive oxygen species, which in turn promoted the occurrence of apoptotic cells in the eye and ultimately impaired ocular structure and visual function during zebrafish development.

Effect of coated cysteamine hydrochloride and probiotics supplemented alone or in combination on feed intake, nutrients digestibility, ruminal fermentation, and blood metabolites of Kamphaeng Saen beef heifers

This study aimed to determine the effects of coated cysteamine hydrochloride (CSH) and probiotics (PB) supplemented alone or in combination on feed intake, digestibility, ruminal fermentation, and blood metabolites of heifer beef cattle. Sixteen heifers (body weight = 210 ± 41 kg; age = 9 ± 2 months) were assigned according to a randomized complete block design in a 2 × 2 factorial arrangement. All animals were fed the basal diet, which contained an 82:17 concentrate-to-forage ratio, and the forage source was rice straw. The treatments were as follows: (1) 0% PB + 0 g/d CSH, (2) 0.1% PB + 0 g/d CSH, (3) 0% PB + 20 g/d CSH, and (4) 0.1% PB + 20 g/d CSH. The main effect of CSH supplementation has been found to improve feed intake (P < 0.05). There were no treatment interactions with nutrient digestibility or rumen fermentation parameters. Supplementation of CSH did not affect any of the variables evaluated, while probiotics supplementation increased DM digestibility due to the increases in CP and fiber fraction digestibility. Compared to controls and CSH, at 16 h post-feeding, heifers receiving probiotics tended (P = 0.07) to show 17% greater ruminal NH3-N concentration, but this effect was not evident at 2 h post-feeding. However, the main effects of probiotic supplementation showed a tendency to increase the number of total bacteria and fungal zoospores in the rumen at 2 h post-feeding. The blood triglyceride (BTG) concentration of heifers fed a diet supplemented with 20 g/d CSH and 0.1% probiotics was found to be greater than those fed CSH alone (P < 0.1) at 16 h post-feeding, and then, there were greater BTG concentrations than other treatments (P < 0.05) at 2 h post-feeding. In conclusion, the combination of CSH and PB did not potentiate the effects of probiotics on digestibility and rumen fermentation and had minimal effects on blood parameters.

The TGM2 inhibitor cysteamine hydrochloride does not impact corneal epithelial and stromal wound healing in vitro and in vivo

Corneal wound healing is integral for resolution of corneal disease or for post-operative healing. However, corneal scarring that may occur secondary to this process can significantly impair vision. Tissue transglutaminase 2 (TGM2) inhibition has shown promising antifibrotic effects and thus holds promise to prevent or treat corneal scarring. The commercially available ocular solution for treatment of ocular manifestations of Cystinosis, Cystaran®, contains the TGM2 inhibitor cysteamine hydrochloride (CH). The purpose of this study is to assess the safety of CH on corneal epithelial and stromal wounds, its effects on corneal wound healing, and its efficacy against corneal scarring following wounding. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were first used to quantify and localize TGM2 expression in the cornea. Subsequently, (i) the in vitro effects of CH at 0.163, 1.63, and 16.3 mM on corneal epithelial cell migration was assessed with an epithelial cell migration assay, and (ii) the in vivo effects of application of 1.63 mM CH on epithelial and stromal wounds was assessed in a rabbit model with ophthalmic examinations, inflammation scoring, color and fluorescein imaging, optical coherence tomography (OCT), and confocal biomicroscopy. Post-mortem assessment of corneal tissue post-stromal wounding included biomechanical characterization (atomic force microscopy (AFM)), histology (H&E staining), and determining incidence of myofibroblasts (immunostaining against α-SMA) in wounded corneal tissue. TGM2 expression was highest in corneal epithelial cells. Application of the TGM2 inhibitor CH did not affect in vitro epithelial cell migration at the two lower concentrations tested. At 16.3 mM, decreased cell migration was observed. In vivo application of CH at 57 mM was well tolerated and did not adversely affect wound healing. No difference in corneal scarring was found between CH treated and vehicle control eyes. This study shows that the TGM2 inhibitor CH, at the FDA-approved dose, is well tolerated in a rabbit model of corneal wound healing and does not adversely affect epithelial or stromal wound healing. This supports the safe use of this medication in Cystinosis patients with open corneal wounds. CH did not have an effect on corneal scarring in this study, suggesting that Cystaran® administration to patients with corneal wounds is unlikely to decrease corneal fibrosis.

Effect of cysteamine hydrochloride-loaded liposomes on skin depigmenting and penetration

Skin hyperpigmentation is caused by an excessive production of melanin. Cysteamine, an aminothiol compound physiologically synthetized in human body cells, is known as depigmenting agent. The aim of this study was to evaluate the depigmenting activity and skin penetration of liposome formulations encapsulating cysteamine hydrochloride. First, cysteamine hydrochloride-loaded liposomes were prepared and characterized for their size, polydispersity index, zeta potential and the encapsulation efficiency of the active molecule. The stability of cysteamine hydrochloride in the prepared liposome formulations in suspension and freeze-dried forms was then assessed. The in vitro cytotoxicity of cysteamine and cysteamine-loaded liposome suspensions (either original or freeze-dried) was evaluated in B16 murine melanoma cells. The measurement of melanin and tyrosinase activities was assessed after cells treatment with free and encapsulated cysteamine. The antioxidant activity of the free and encapsulated cysteamine was evaluated by the measurement of ROS formation in treated cells. The ex vivo human skin penetration study was also performed using Franz diffusion cell. The stability of cysteamine hydrochloride was improved after encapsulation in liposomal suspension. In addition, for the liposome re-suspended after freeze-drying, a significant increase of vesicle stability was observed. The free and the encapsulated cysteamine in suspension (either original or freeze-dried) did not show any cytotoxic effect, inhibited the melanin synthesis as well as the tyrosinase activity. An antioxidant activity was observed for the free and the encapsulated cysteamine hydrochloride. The encapsulation enhanced the skin penetration of cysteamine hydrochloride. The penetration of this molecule was better for the re-suspended freeze-dried form than the original liposomal suspension where the drug was found retained in the epidermis layer of the skin.

Identification, characterization of selenoprotein W and its mRNA expression patterns in response to somatostatin 14, cysteamine hydrochloride, 17β-estradiol and a binary mixture of 17β-estradiol and cysteamine hydrochloride in topmouth culter (Erythroculter ilishaeformis)

In this study, a selenoprotein W cDNA was cloned from topmouth culter (Erythroculter ilishaeformis), and it was designated as EISelW. The EISelW open reading frame was composed of 261 base pairs (bp), encoding 86-amino-acid protein. The 5' untranslated region (UTR) consisted of 104 bp, and the 3'-UTR was composed of 365 bp. A selenocysteine insertion sequence (SECIS) element was found in the 3'-UTR of EISelW mRNA. The SECIS element was classified as form II because of a small additional apical loop presented in SECIS element of EISelW mRNA. Bioinformatic approaches showed that the secondary structure of EISelW was a β1-α1-β2-β3-β4-α2 pattern from amino-terminal to carboxy-terminal. Real-time PCR analysis of EISelW mRNAs expression in 17 tissues showed that the EISelW mRNA was predominantly expressed in liver, ovary, pituitary, various regions of the brain, spinal cord and head kidney. Study of intraperitoneal injection showed that the levels of EISelW mRNA in brain, liver, ovary and spleen were regulated by somatostatin 14 (SS14), 17β-estradiol (E2), cysteamine hydrochloride (CSH) and a binary mixture of E2 and CSH, dependent on the dosage. These results suggest that E2, SS14 and CSH status may affect tissues of selenium metabolism by regulating the expression of SelW mRNA, as SelW plays a central role in selenium metabolism.

A new gel formulation of topical cysteamine for the treatment of corneal cystine crystals in cystinosis: the Cystadrops OCT-1 study

OBJECTIVE

To establish the safety and efficacy of a new gel formulation of cysteamine hydrochloride (CH) eye drops, for the treatment of corneal complications of nephropathic cystinosis.

DESIGN

Open label dose response clinical trial.

PARTICIPANTS

Eight patients with infantile nephropathic cystinosis including 4 children, 3 adolescents, and 1 adult (mean age at inclusion, 12.1 ± 4.6 years) treated with CH 0.1% eye drops.

INTERVENTION

Patients were treated, in both eyes, with the control CH 0.1% eye drop formulation on average 4 times daily for one month and then switched to Cystadrops® at the same dose frequency. Based on clinical ocular findings, the dose regimen was adapted at D30 and D90 in order to decrease the frequency of instillation. After D90, this dose frequency was maintained, except in cases of crystal density worsening. Patients had a follow-up visit every 6 months during 48 months.

MAIN OUTCOME MEASURES

Safety assessment consisted of adverse event and serious adverse event monitoring and recording at each visit. For the efficacy study, the primary endpoint was the corneal cystine crystal density measured with an in vivo confocal microscopy (IVCM) score.

RESULTS

All patients completed the study. During the 4-year study period, neither serious adverse events nor significant adverse events related to the study drug were reported. After switching to Cystadrops®, the IVCM total score decreased from baseline to D90 by a mean of 28.6 ± 17.5% (p<0.001). From D90 to M48, the IVCM total score remained stable and significantly decreased as compared to that at D1 despite a reduced dose regimen from D90. At M48, the mean IVCM total score was 8.13 ± 4.15, decreased by a mean 29.9 ± 26.29% from D1 (p = 0.001), with a reduced number of instillations compared to that at D1. The IVCM total score and photophobia were significantly correlated (p = 0.04).

CONCLUSION

This study provides evidence that Cystadrops® gel is superior to the CH 0.1% formulation in terms of efficacy and has a good safety profile over a long follow-up period.