Evaluation of ocular irritancy of coal-tar dyes used in cosmetics employing reconstructed human cornea-like epithelium and short time exposure tests

Performance of Dye Removal from Single and Binary Component Systems by Adsorption on Composite Hydrogel Beads Derived from Fruits Wastes Entrapped in Natural Polymeric Matrix

The treatment of contaminated water is currently a major concern worldwide. This work was directed towards the preparation of a composite hydrogel by entrapping cherry stones powder on chitosan, which is known as one of the most abundant natural polymers. The synthesized material was characterized by scanning electron microscopy, by Fourier transform infrared spectroscopy, and by the point of zero charge determination. Its ability to remove two azo dyes models (Acid Red 66 and Reactive Black 5) existing in single form and in binary mixture was evaluated. Response Surface Methodology-Central Composite Design was used to optimize three parameters affecting the process while targeting the lowest final contaminant concentrations. The best results were obtained at pH 2, an adsorbent dose of 100 g/L, and a temperature of 30 °C, when more than 90% of the pollutants from the single component systems and more than 70% of those of the binary mixtures were removed from their aqueous solutions. The adsorption process was in accordance with Elovich and pseudo-second-order kinetic models, and closely followed the Freundlich and Temkin equilibrium isotherms. The obtained results led to the conclusion that the prepared hydrogel composite possesses the ability to successfully retain the target molecules and that it can be considered as a viable adsorbent material.

Employment of cytology for in vitro skin irritation test using a reconstructed human epidermis model, Keraskin™

Skin irritation tests using reconstructed human epidermis (RhE) employ viability as an endpoint, but color interference or borderline results are often problematic. We examined whether the cytology of cells from treated RhE could determine skin irritancy. Six chemicals (three irritants; DnP, 1-B, PH, three non-irritants; DP, APA, HS) were evaluated in a RhE, Keraskin™. DP, HS, and PH were clearly classified with viability, but DnP, 1-B, and APA were often falsely determined, due to borderline values falling near the cutoff, 50%. In histology, the tissues treated with DnP, 1-B, and PH showed erosion of the stratum corneum, vacuolization, and necrosis in the basal layer. DP- and HS-treated tissues showed relatively normal morphology but APA induced necrosis similar to irritants. Cytology revealed that DnP, 1-B or PH depleted cells and induced irregular and abnormal cell shapes. In contrast, relatively regular and normal shapes and clear distinction between the nucleus and cytoplasm was observed for DP, APA and HS. To further confirm it, additional 10 substances, including false positives from OECD TG 439, were tested. Overall (16 substances in total), cytology: total area predicted the skin irritancy of test chemicals with the highest accuracy (87.5%) followed by cytology: cell count (81.3%), histology (75%) and viability (68.8%), confirming the utility of cytology as an alternative endpoint in the skin irritation test using RhE.

Development and validation of UPLC method for WST-1 cell viability assay and its application to MCTT HCE™ eye irritation test for colorful substances

WST-1 [Water Soluble Tetrazolium-1; 2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt)] is widely used in the cell viability assays replacing MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). A water-soluble formazan dye (4-[1-(4-Iodophenyl)-5-(4-nitrophenyl)formaz-3-yl]-1,3-benzene disulfonate, disodium salt) is produced from the reduction of WST-1 tetrazolium, of which optical density at 450 nm is measured to evaluate cell viability. Colorful substances may interfere with spectrometric measurement, and a method to specifically detect WST-1 formazan is required. Here, a simple, rapid, sensitive, and specific ultra-performance liquid chromatography coupled to UV detector (UPLC-UV) was developed and validated for the WST-1 formazan. For the application to cell viability assay, the supernatant from WST-1 assay was injected without sample preparation procedure and a single run was completed within 5 min. Chromatographic separation was achieved on BEH C18 column (1.7 μm, 2.1 × 50 mm) using gradient elution with the mobile phase of water and acetonitrile. The standard curves were linear over the concentration range of 2.5-120 μg/mL WST-1 formazan, which encompasses WST-1 formazan concentrations from 2% cell viability to 2 fold of 100% cell viability. The intra- and inter-day precisions were measured to be below 5% and accuracies were within the range of 91.8-104.9%. The validated method was successfully applied to the test of colorful substances in vitro eye irritation test with a human cornea-like epithelium, and in vitro cytotoxicity in HaCaT, human keratinocyte cell line.

Fasiglifam (TAK-875), a G Protein-Coupled Receptor 40 (GPR40) Agonist, May Induce Hepatotoxicity through Reactive Oxygen Species Generation in a GPR40-Dependent Manner

Fasiglifam (TAK-875) a G-protein coupled receptor 40 (GPR40) agonist, significantly improves hyperglycemia without hypoglycemia and weight gain, the major side effects of conventional anti-diabetics. Unfortunately, during multi-center Phase 3 clinical trials, unexpected liver toxicity resulted in premature termination of its development. Here, we investigated whether TAK-875 directly inflicts toxicity on hepatocytes and explored its underlying mechanism of toxicity. TAK-875 decreased viability of 2D and 3D cultures of HepG2, a human hepatocarcinoma cell line, in concentration- (>50 μM) and time-dependent manners, both of which corresponded with ROS generation. An antioxidant, N-acetylcysteine, attenuated TAK-875-mediated hepatotoxicity, which confirmed the role of ROS generation. Of note, knockdown of GPR40 using siRNA abolished the hepatotoxicity of TAK-875 and attenuated ROS generation. In contrast, TAK-875 induced no cytotoxicity in fibroblasts up to 500 μM. Supporting the hepatotoxic potential of TAK-875, exposure to TAK-875 resulted in increased mortality of zebrafish larvae at 25 μM. Histopathological examination of zebrafish exposed to TAK-875 revealed severe hepatotoxicity as manifested by degenerated hypertrophic hepatocytes with cytoplasmic vacuolation and acentric nuclei, confirming that TAK-875 may induce direct hepatotoxicity and that ROS generation may be involved in a GPR40-dependent manner.

Potentiation of skin TSLP production by a cosmetic colorant leads to aggravation of dermatitis symptoms

Certain cosmetic colorants are irritant to skin or aggravate dermatitis. Thymic stromal lymphopoietin (TSLP) plays an important role in the initiation and progress of skin inflammation and atopic dermatitis by triggering Th2 immune responses. However, the effects of cosmetic colorants on TSLP production are unknown yet. Therefore, we investigated whether cosmetic colorants regulated TSLP production and dermatitis. Lithol Rubine B (LR-B, Pigment Red 57) and its calcium salt (LR-BCA), commonly used cosmetic colorants, potentiated phorbol-12-myristate-13-acetate-induced TSLP production in keratinocytes. In addition, the topical exposure to LR-B or LR-BCA on mouse ear upregulated a TSLP inducer (MC903)-induced TSLP production and Th2 cytokine expression. Dermatitis symptoms and serum IgE and histamine levels were also aggravated by LR-B or LR-BCA, implicating the role of increased TSLP expression in acute dermatitis. LR-B or LR-BCA induced IκBα degradation and NF-κB activation in keratinocytes, leading to TSLP expression. Collectively, our results demonstrate that LR-B and LR-BCA increase TSLP expression and Th2 immune responses, thereby aggravating acute dermatitis in the compromised skin. The results further suggest that certain cosmetic colorants such as LR-B may aggravate dermatitis under pro-inflammatory conditions by upregulating TSLP production.