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1.
Toxicology ; 504: 153783, 2024 May.
Article in English | MEDLINE | ID: mdl-38518840

ABSTRACT

Despite the wide application of graphene-based materials, the information of the toxicity associated to some specific derivatives such as aminated graphene oxide is scarce. Likewise, most of these studies analyse the pristine materials, while the available data regarding the harmful effects of degraded forms is very limited. In this work, the toxicity of graphene oxide (GO), aminated graphene oxide (GO-NH2), and their respective degraded forms (dGO and dGO-NH2) obtained after being submitted to high-intensity sonication was evaluated applying in vitro assays in different models of human exposure. Viability and ROS assays were performed on A549 and HT29 cells, while their skin irritation potential was tested on a reconstructed human epidermis model. The obtained results showed that GO-NH2 and dGO-NH2 substantially decrease cell viability in the lung and gastrointestinal models, being this reduction slightly higher in the cells exposed to the degraded forms. In contrast, this parameter was not affected by GO and dGO which, conversely, showed the ability to induce higher levels of ROS than the pristine and degraded aminated forms. Furthermore, none of the materials is skin irritant. Altogether, these results provide new insights about the potential harmful effects of the selected graphene-based nanomaterials in comparison with their degraded counterparts.


Subject(s)
Cell Survival , Graphite , Nanostructures , Reactive Oxygen Species , Graphite/toxicity , Graphite/chemistry , Humans , Cell Survival/drug effects , Reactive Oxygen Species/metabolism , A549 Cells , Nanostructures/toxicity , Nanostructures/chemistry , HT29 Cells , Skin Irritancy Tests/methods
2.
Biosensors (Basel) ; 13(2)2023 Jan 20.
Article in English | MEDLINE | ID: mdl-36831928

ABSTRACT

The rabbit skin irritation test has been the standard for evaluating the irritation potential of chemicals; however, alternative methods that do not use animal testing are actively encouraged. Reconstructed human epidermis (RhE) models mimic the biochemical and physiological properties of the human epidermis and can be used as an alternative method. On RhE methods, the metabolic activity of RhE models is used to predict skin irritation, with a reduction in metabolic activity indicating a reduced number of viable cells and linking cell death to skin irritation processes. However, new challenges have emerged as the use of RhE models increases, including the need for non-invasive and marker-free methodologies to assess cellular states. Electrochemical impedance spectroscopy (EIS) is one such methodology that can meet these requirements. In this study, our results showed that EIS can differentiate between irritant and non-irritant chemicals, with a significant increase in the capacitance values observed in the irritant samples. A ROC curve analysis showed that the prediction method based on EIS met OECD TG 439 requirements at all time points and had 95% within-laboratory reproducibility. Comparison with the MTT viability assay showed that prediction using EIS achieved higher sensitivity, specificity, and accuracy. These results suggest that EIS could potentially replace animal testing in the evaluation of irritation potential and could be a valuable addition to in vitro testing strategies.


Subject(s)
Dielectric Spectroscopy , Skin Irritancy Tests , Animals , Humans , Rabbits , Reproducibility of Results , Skin Irritancy Tests/methods , Animal Testing Alternatives , Epidermis
3.
J Appl Toxicol ; 43(6): 874-886, 2023 06.
Article in English | MEDLINE | ID: mdl-36594553

ABSTRACT

The aim of this study is to validate an in vitro skin irritation test (SIT) using three-dimensional reconstructed human epidermal (RhE) skin equivalents prepared by layer-by-layer (LbL) method (LbL-3D Skin) in a series of interlaboratory studies. The goal of these validation studies is to evaluate the ability of this in vitro test to reliably discriminate skin irritant from nonirritant chemicals, as defined by OECD and UN GHS. This me-too validation study is to assess the within- and between-laboratory reproducibility, as well as the predictive capacity, of the LbL-3D Skin SIT in accordance with performance standards for OECD TG 439. The developed skin model, LbL-3D Skin had a highly differentiated epidermis and dermis, similar to the validated reference methods (VRM) and native human skin. The quality parameters (cell survival in controls, tissue integrity, and barrier function) were similar to VRM and in accordance with OECD TG 439. The LbL-3D Skin SIT validation study was performed by three participating laboratories and consisted of three independent tests using 20 reference chemicals. The results obtained with the LbL-3D Skin demonstrated high within-laboratory and between-laboratory reproducibility, as well as high accuracy for use as a stand-alone assay to distinguish skin irritants from nonirritants. The predictive potency of LbL-3D Skin SIT using total 54 test chemicals were comparable to those in other RhE models in OECD TG 439. The validation study demonstrated that LbL-3D Skin has proven to be a robust and reliable method for predicting skin irritation.


Subject(s)
Irritants , Skin Irritancy Tests , Humans , Animals , Reproducibility of Results , Skin Irritancy Tests/methods , Irritants/toxicity , Skin , Epidermis , In Vitro Techniques , Animal Testing Alternatives
4.
Sci Rep ; 12(1): 20991, 2022 12 05.
Article in English | MEDLINE | ID: mdl-36471154

ABSTRACT

In the present study, a comparative human toxicity assessment between newly developed Mn3O4 nanoparticles with enhanced electrochemical properties (GNA35) and their precursor material (Mn3O4) was performed, employing different in vitro cellular models representing main exposure routes (inhalation, intestinal and dermal contact), namely the human alveolar carcinoma epithelial cell line (A549), the human colorectal adenocarcinoma cell line (HT29), and the reconstructed 3D human epidermal model EpiDerm. The obtained results showed that Mn3O4 and GNA35 harbour similar morphological characteristics, whereas differences were observed in relation to their surface area and electrochemical properties. In regard to their toxicological properties, both nanomaterials induced ROS in the A549 and HT29 cell lines, while cell viability reduction was only observed in the A549 cells. Concerning their skin irritation potential, the studied nanomaterials did not cause a reduction of the skin tissue viability in the test conditions nor interleukin 1 alpha (IL- 1 α) release. Therefore, they can be considered as not irritant nanomaterials according to EU and Globally Harmonized System of Classification and Labelling Chemicals. Our findings provide new insights about the potential harmful effects of Mn3O4 nanomaterials with different properties, demonstrating that the hazard assessment using different human in vitro models is a critical aspect to increase the knowledge on their potential impact upon different exposure routes.


Subject(s)
Irritants , Nanostructures , Humans , Irritants/toxicity , Skin Irritancy Tests/methods , Oxides , Nanostructures/toxicity
5.
Toxicol In Vitro ; 82: 105371, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35487444

ABSTRACT

Irritation testing is an integral part of the biocompatibility assessment of medical devices and has historically been conducted on animals, either by direct contact or with polar and non-polar solvent extracts. In 2018 an ISO-sponsored interlaboratory validation study demonstrated that two reconstituted human epidermis (RhE) based assays, which were adapted from validated methods used for industrial chemicals, produced results essentially equivalent to those obtained with in vivo tests. This led to the publication of the ISO 10993-23:2021 standard on irritation testing, which states that RhE-based assays are now the preferred method. The 2018 validation study evaluated strong irritants, so we tested nine mild irritants (GHS Category 3), neat and spiked at different concentrations into medical device extracts, per ISO 10993-23:2021. The results substantiated the applicability of RhE-based assays for evaluating mild irritants in medical device extracts. Moreover, the 2018 validation study tested solid extractable medical device materials but did not consider non-extractable medical device materials (e.g., creams, gels, or sprays). By testing nine marketed non-extractable materials, either neat or spiked with irritants, we also confirmed that RhE-based assays are readily applicable to such medical device materials.


Subject(s)
Irritants , Skin Irritancy Tests , Animal Testing Alternatives , Animals , Epidermis , In Vitro Techniques , Irritants/toxicity , Skin Irritancy Tests/methods
6.
ALTEX ; 39(3): 405­418, 2022.
Article in English | MEDLINE | ID: mdl-35319071

ABSTRACT

There is a global trend towards the development of physiologically relevant in vitro skin models to reduce or replace animal testing in the evaluation of therapeutic drug candidates. However, only commercial reconstructed human epidermis models (RHEm) have undergone formal validation. Although these commercial models are suitable for a wide range of applications, they are costly, lack flexibility, and the protocols used to generate them are not transparent. In this study, we present an open-source full-thickness skin model (FTSm) and assess its potential for drug testing. The FTSm was developed using endogenous extracellular matrix to recreate the dermal compartment, avoiding animal-derived hydrogels. An RHEm based on an open-source protocol was evaluated in parallel. The integrity of the skin barrier was analyzed by challenging the surface with detergents and measuring cell viability as well as by trans-epithelial electrical resistance (TEER) measurements. Skin irritation studies were performed based on OECD guidelines and complemented with an evaluation of the impact on the skin barrier by TEER measurement. The permeation of a dye through the developed models and a commercial membrane (Strat-M®) was compared using Franz diffusion cells and an infinite dose approach. The FTSm demonstrated structural and barrier properties comparable to native human skin. Although the RHEm showed a better performance in drug testing, the FTSm presented better barrier properties than commercial models as reported in the literature. These skin models can be a valuable contribution to accelerating the development and dissemination of alternatives to animal testing, avoiding the limitations of commercial models.


Subject(s)
Irritants , Skin Irritancy Tests , Animal Testing Alternatives/methods , Animals , Epidermis , Humans , Skin , Skin Irritancy Tests/methods
7.
Pharm Dev Technol ; 26(9): 967-977, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34382493

ABSTRACT

In this study, permeation behaviors and chemical stability of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica (PM), Thai traditional medicine, crude extract containing transdermal gels were firstly evaluated. Three different PM extract containing gels were formulated, including hydroalcoholic and microemulsion gels using carbomer, and silicone gel using silicone elastomer. In vitro permeation through porcine ear skin demonstrated that the flux and 24 h cumulative permeation of miroestrol and deoxymiroestrol were in the order of hydroalcoholic > silicone > microemulsion gels. Hydroalcoholic gel provided the highest partition coefficient from gel onto skin, and thus the skin permeability coefficient. After 24 h permeation, no miroestrol and deoxymiroestrol remained deposited in the skin. Accelerated study using heating-cooling revealed insignificant difference between the remaining percentages of miroestrol and deoxymiroestrol in aqueous and non-aqueous based gels. Long-term stability study showed that miroestrol contents remained constant for 90 d and 30 d under 5 ± 3 °C and 30 ± 2 °C, 75 ± 5%RH, respectively; whereas the percentage of deoxymiroestrol decreased significantly after 30 d storage, irrespective of storage conditions. Acute dermal irritation test on New Zealand White rabbits showed that PM hydroalcoholic gels were non-irritant, with no signs of erythema or oedema.[Figure: see text].


Subject(s)
Plant Extracts/metabolism , Pueraria , Skin Absorption/drug effects , Skin Irritancy Tests/methods , Steroids/metabolism , Administration, Cutaneous , Animals , Coumarins/administration & dosage , Coumarins/metabolism , Coumarins/toxicity , Drug Stability , Estrogens, Non-Steroidal/administration & dosage , Estrogens, Non-Steroidal/metabolism , Estrogens, Non-Steroidal/toxicity , Gels , Male , Organ Culture Techniques , Plant Extracts/administration & dosage , Plant Extracts/toxicity , Rabbits , Skin/drug effects , Skin/metabolism , Skin Absorption/physiology , Steroids/administration & dosage , Steroids/toxicity , Swine
8.
Chem Res Toxicol ; 34(7): 1749-1758, 2021 07 19.
Article in English | MEDLINE | ID: mdl-34110798

ABSTRACT

Aldehydes comprise a major portion of skin sensitizers because they can react with both cysteine and lysine. Moreover, cinnamaldehyde (CA) is a typical moderate sensitizer and is often used in an alternative test method for skin sensitization. The amino acid derivative reactivity assay (ADRA) is an in chemico test method that evaluates the reactivity of cysteine derivatives (N-(2-(1-naphthyl)acetyl)-l-cysteine, NAC) and lysine derivatives with the test chemicals and uses CA as a proficiency substance. We found that NAC depletion for CA was only 10-20% when CA was used directly from the reagent bottle, although it increased to almost 100% when stored after being aliquoted from the reagent bottle. It was also found that this was due to the air oxidation of NAC itself rather than the reaction of NAC with CA, indicating that this result simply shows an increase in apparent reactivity. Aldehydes are known to produce active species, such as radicals, during air oxidation. Therefore, we investigated whether radicals were generated under storage conditions using the radical scavenger OH-TEMPO. LC/MS/MS analysis revealed that CA and OH-TEMPO complexes were produced during the air oxidation of CA. In the results of five aldehydes, similar to CA, active species were not generated as significantly as CA. Collectively, during the evaluation of the aldehydes, it can be seen that careful measures need to be taken to prevent the aldehydes from oxidizing during storage, indicating that assessment without preventing air oxidation carries an increased risk of overestimation compared with the intrinsic skin sensitization potency.


Subject(s)
Acrolein/analogs & derivatives , Cysteine/chemistry , Acrolein/chemistry , Animals , Chromatography, High Pressure Liquid/methods , Cyclic N-Oxides/chemistry , Humans , Indicators and Reagents , Oxidation-Reduction , Skin/drug effects , Skin Irritancy Tests/methods , Tandem Mass Spectrometry/methods
9.
Regul Toxicol Pharmacol ; 123: 104922, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33819554

ABSTRACT

Skin irritation is a key human health endpoint assessed by in vitro and in vivo methods. The OECD TG 404 guideline (in vivo) is based on erythema and oedema translated semi-quantitatively into Draize scores, providing hazard statements for substance classification following EUCLP/UNGHS criteria. Draize scores require quantitation from subjective in vivo observations, to obtain a scoring index, the Primary Irritation Index (PII). However, it is not recognised under REACH due to translating difficulties, notably the cut-off limit for classification and non-inclusion of corrosive effects. The aim of this study was to determine if classification can be driven by just one of the observed effects, erythema only, to create a Simplified Irritation Index (SIISKIN). This simplifies the scoring calculation and reduces subjectivity. A quantitative approach with cut-off limits is thus proposed for classification. Substances can be classified as non-irritant, potentially irritant, irritant, or corrosive. The Simplifed Irritation Index (SIISKIN) is based on validated studies, representing multiple chemical groups. A significant correlation between SIISKIN and the harmonised classification was observed, and a proportionate relationship between the SIISKIN and the corresponding PII. The index proved to be useful in the development of an in silico model.


Subject(s)
Caustics/toxicity , Computer Simulation , Irritants/toxicity , Skin Irritancy Tests/methods , Animal Testing Alternatives , Corrosion , Humans , Skin , Skin Diseases
10.
Food Chem Toxicol ; 150: 112064, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33596452

ABSTRACT

Biocides are widely used in household products. Humans are exposed to biocides through dermal, inhalational, and oral routes. However, information on the dermal and inhalational toxicity of biocides is limited. We evaluated the effects of biocides on the skin and airways using the reconstructed human epidermis model KeraSkin™ and the airway model SoluAirway™. We determined the irritancy of 11 commonly used biocides (1,2-benzisothiazol-3(2H)-one [BIT], 2-phenoxyethanol [PE], zinc pyrithione, 2-bromo-2-nitropropane-1,3-diol, 3-iodoprop-2-ynyl N-butylcarbamate [IPBC], 2-octyl-1,2-thiazol-3-one, 2,2-dibromo-2-cyanoacetamide, 4-chloro-3-methylphenol [CC], 2-phenylphenol, deltamethrin, and 4,5-dichloro-2-octyl-1,2-thiazol-3-one) in the KeraSkin™ and SoluAirway™ by viability and histological examinations. BIT and CC were found to cause skin irritation at the approved concentrations or at the concentration close to approved limit while the others were non-irritants within the approved concentration. These results were confirmed via histology, wherein skin irritants induced erosion, vacuolation, and necrosis of the tissue. In the SoluAirway™, most of the biocides decreased cell viability even within the approved limits, except for PE, IPBC, and deltamethrin, suggesting that the airway may be more vulnerable to biocides than the skin. Taken together, our result indicates that some biocides can induce toxicity in skin and airway. Further studies on the dermal and inhalational toxicity of biocides are warranted.


Subject(s)
Epidermal Cells/drug effects , Irritants/toxicity , Skin Irritancy Tests/methods , Animal Testing Alternatives , Disinfectants , Epidermis/drug effects , Humans , In Vitro Techniques , Models, Biological , Respiratory System/drug effects
11.
Methods Mol Biol ; 2240: 13-29, 2021.
Article in English | MEDLINE | ID: mdl-33423223

ABSTRACT

Contact allergy is of considerable importance to the toxicologist, and regulatory authorities worldwide require testing for skin sensitization potential and appropriate hazard labeling to enable management of the risk to human health. Although traditionally the identification of skin-sensitizing chemicals has been carried out using animal models, in Europe legislative changes have promoted, and now require, the use of non-animal methods (i.e., Cosmetic Directive, REACH). Several in vitro alternatives for hazard identification have now been validated, but do not provide information on the potency of a skin sensitizer. Here, we describe an animal model, the local lymph node assay (LLNA), and an in vitro model, the RhE IL-18 potency assay, in the context of the identification and potency classification of skin sensitizers. These two assays have been chosen among the different available tests as representative of an alternative in vivo model (the LLNA) and a promising in vitro method with the potential of both hazard identification and potency classification.


Subject(s)
Dermatitis, Allergic Contact/etiology , Interleukin-18/immunology , Local Lymph Node Assay , Skin Irritancy Tests/methods , Allergens/immunology , Allergens/toxicity , Animals , Cells, Cultured , Dermatitis, Allergic Contact/diagnosis , Dermatitis, Allergic Contact/immunology , Humans , Irritants/immunology , Irritants/toxicity , Keratinocytes/drug effects , Keratinocytes/immunology , Mice , Primary Cell Culture/methods
12.
Methods Mol Biol ; 2240: 31-41, 2021.
Article in English | MEDLINE | ID: mdl-33423224

ABSTRACT

This chapter presents the protocols for developing of skin equivalents (SE) and reconstructed human epidermis (RHE) models for dermal toxicity evaluation as an alternative method to animal use in research. It provides a detailed protocol for the in vitro reconstruction of human skin from primary keratinocytes, melanocytes, and fibroblasts obtained from foreskin biopsies, including the procedures for reconstruction of a stratified epidermis on a polyester membrane. SE and RHE developed through these methods have been proven suitable not only for dermal toxicity studies, but also for investigating of pathological conditions in the skin, such as diabetes and invasion of melanoma.


Subject(s)
Epidermis/drug effects , Primary Cell Culture/methods , Skin Irritancy Tests/methods , Cells, Cultured , Humans
13.
Toxicol In Vitro ; 70: 105030, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33058998

ABSTRACT

When developing new cosmetics, it is extremely important to consider the safety of consumers. Absence of potential irritancy is generally assessed using an OECD TG439 compliant Reconstructed Human Epidermis (RHE) systems and MTT assays, resulting in an irritant/not irritant classification. To gain insight into the irritancy of molecules/finished cosmetic products and to predict the outcome of irritation tests performed on subjects whatever their nature, we developed a test that uses skin explants and histological analysis. Results showed that this irritation test is sensitive enough to accurately and repeatably detect known irritants. If the diverse origin of the skin explants used led to variability in the histological alterations scored, the overall grading of irritancy is highly reproducible. Finally, when testing 120 non-alcoholic cosmetics of various galenic forms, comparison of data between the ex vivo irritation tests and of a 24-/48-h human patch test revealed a single false negative, very close to the limit, and a 10% false positive rate. It was not possible to calculate the sensitivity of the ex vivo irritation test; however, its specificity was 89.9% and its accuracy was 89.1%. Similar results, with a slightly higher false positive rate, were found when testing 49 alcoholic cosmetics. These values exceed the minimum requirements of OECD TG439.


Subject(s)
Cosmetics/toxicity , Irritants/toxicity , Skin Irritancy Tests/methods , Skin/drug effects , Adolescent , Adult , Female , Humans , In Vitro Techniques , Male , Middle Aged , Reproducibility of Results , Sensitivity and Specificity , Skin/pathology , Young Adult
14.
Toxicol In Vitro ; 71: 105069, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33309870

ABSTRACT

Three-dimensional skin models, also named 3D skin models, human skin equivalents (HSEs), or Human Epidermal Equivalents (HEEs), have been increasingly used for chemical assessments in terms of efficacy and safety. Considering this, we developed an HEE model using immortalized HaCaT cells, aiming to overcome the limitation of primary tissue source. Our 3D model (HaCaT-HEE) exhibited important markers of cell differentiation (CK10, CK14, involucrin, and filaggrin), although the stratum corneum was shown to be modest. Besides, the model showed a good prediction potential considering membrane permeability, sensitivity, specificity, and accuracy in distinguishing irritant and corrosive effects after exposure to selected chemicals recommended by the OECD protocols. We also validated the formazan determination for the MTT method using High-Performance Liquid Chromatography (HPLC). For that, we considered carry over, linearity, reproducibility/robustness, accuracy, precision, selectivity, and matrix effect, according to the Food and Drug Administration (FDA) guideline. Based on our results, we can conclude that our model has an acceptable predictive value for the safety evaluation of compounds after skin exposure, with the great advantage of being constructed using immortalized cells.


Subject(s)
Caustics/toxicity , Irritants/toxicity , Keratinocytes/drug effects , Skin Irritancy Tests/methods , Animal Testing Alternatives , Cell Line , Cell Membrane Permeability/drug effects , Epidermis , Filaggrin Proteins , Humans
15.
Molecules ; 25(23)2020 Nov 27.
Article in English | MEDLINE | ID: mdl-33261007

ABSTRACT

Capsaicin is an active compound in chili peppers (Capsicum chinense) that has been approved for chronic pain treatment. The topical application of high-strength capsaicin has been proven to reduce pain; however, skin irritation is a major drawback. The aim of this study was to investigate an appropriate and scalable technique for preparing nanostructured lipid carriers (NLCs) containing 0.25% capsaicin from capsicum oleoresin (NLC_C) and to evaluate the irritation of human skin by chili-extract-loaded NLCs incorporated in a gel formulation (Gel NLC_C). High-shear homogenization with high intensity (10,000 rpm) was selected to create uniform nanoparticles with a size range from 106 to 156 nm. Both the NLC_C and Gel NLC_C formulations expressed greater physical and chemical stabilities than the free chili formulation. Release and porcine biopsy studies revealed the sustained drug release and significant permeation of the NLCs through the outer skin layer, distributing in the dermis better than the free compounds. Finally, the alleviation of irritation and the decrease in uncomfortable feelings following the application of the Gel NLC_C formulation were compared to the effects from a chili gel and a commercial product in thirty healthy volunteers. The chili-extract-loaded NLCs were shown to be applicable for the transdermal delivery of capsaicin whilst minimizing skin irritation, the major noncompliance cause of patients.


Subject(s)
Capsaicin/administration & dosage , Capsicum/chemistry , Drug Delivery Systems , Nanostructures/administration & dosage , Skin Irritancy Tests/methods , Skin/drug effects , Administration, Cutaneous , Adult , Delayed-Action Preparations , Female , Humans , Male , Middle Aged , Nanostructures/chemistry , Young Adult
16.
Allergol. immunopatol ; 48(6): 576-581, nov.-dic. 2020. graf, tab
Article in English | IBECS | ID: ibc-199245

ABSTRACT

INTRODUCTION: Eosinophilic esophagitis (EoE) is a chronic, local immune-mediated esophageal disease that has been on the increase lately. There is currently enough evidence to conclude that EoE is an allergic disorder triggered by food allergens, with cow's milk (CM) being the most frequent. Dietary intervention is the first-line approach. This study aimed to assess the clinical characteristics, the diagnostic method, and the prognosis of patients whose culprit food was CM, as opposed to other triggers. METHODS: Children with EoE evaluated in our pediatric Allergy Department were retrospectively studied from 2004 to 2017. We collected clinical variables, diagnostic protocol, treatment, and follow-up data. We compared patients whose culprit food was CM and patients with EoE due to other causative agents. RESULTS: We analyzed 31 children with EoE and found the causative food to be cow's milk in 14 (45%). Clinical characteristics were similar in patients with EoE due to milk or any other cause. Eight of 14 patients with milk-induced EoE (57.14%) presented positive skin prick test results against cow's milk. All patients had positive IgE against cow's milk. None of the patients had any other food as the trigger. The median follow-up was 2.68 years (6 months to 9 years) with initial remission of 100%. CONCLUSION: Testing-based elimination diets effectively treated all of the patients with milk-induced EoE. The advantage of this diagnostic protocol is that it required a mean of only two foods to be tested, significantly smaller number than in empiric diets


No disponible


Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Adolescent , Eosinophilic Esophagitis/diagnosis , Eosinophilic Esophagitis/immunology , Milk Hypersensitivity/complications , Milk Hypersensitivity/diagnosis , Breast-Milk Substitutes , Skin Irritancy Tests/methods , Retrospective Studies , Follow-Up Studies , Immunoglobulin E/blood , Allergens/analysis , Food Hypersensitivity/complications , Food Hypersensitivity/diagnosis
17.
J Toxicol Sci ; 45(11): 725-735, 2020.
Article in English | MEDLINE | ID: mdl-33132246

ABSTRACT

The purpose of this study was to evaluate the sensitization potential of 82 compounds classified as volatile and/or semi-volatile organic compounds using the direct peptide reactivity assay (DPRA), given that these chemical compounds have been detected frequently and at high concentrations in a national survey of Japanese indoor air pollution and other studies. The skin sensitization potential of 81 of these compounds was evaluable in our study; one compound co-eluted with cysteine peptide and was therefore not evaluable. Twenty-five of the evaluated compounds were classified as positive. Although all glycols and plasticizers detected frequently and at high concentrations in a national survey of Japanese indoor air pollution were negative, hexanal and nonanal, which are found in fragrances and building materials, tested positive. Monoethanolamine and 1,3-butanediol, which cause clinical contact dermatitis, and several compounds reported to have weak sensitization potential in animal studies, were classified as negative. Thus, it was considered that compounds with weak sensitization potential were evaluated as negative in the DPRA. Although the sensitization potential of the formaldehyde-releasing preservative bronopol has been attributed to the release of formaldehyde (a well-known contact allergen) by its degradation, its degradation products-bromonitromethane and 2-bromoethanol-were classified as positive, indicating that these degradation products also exhibit sensitization potential. The compounds that tested positive in this study should be comprehensively assessed through multiple toxicity and epidemiological studies.


Subject(s)
Air Pollution, Indoor/analysis , Skin Irritancy Tests/methods , Volatile Organic Compounds/analysis , Volatile Organic Compounds/toxicity , Aldehydes , Animals , Biodegradation, Environmental , Dermatitis, Contact/etiology , Formaldehyde , Glycolates , Humans , Japan , Odorants , Peptides , Plasticizers , Skin , Volatile Organic Compounds/classification
18.
Toxicol In Vitro ; 69: 104995, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32891721

ABSTRACT

The ISO 10993 standards on biocompatibility assessment of medical devices discourage the use of animal tests when reliable and validated in vitro methods are available. A round robin validation study of in vitro reconstructed human epidermis (RhE) assays was performed as potential replacements for rabbit skin irritation testing. The RhE assays were able to accurately identify strong irritants in dilute medical device extracts. However, there was some uncertainty about whether RhE tissues accurately predicted the results of the rabbit skin patch or intracutaneous irritation test. To address that question, this paper presents in vivo data from the round robin and subsequent follow-up studies. The follow-up studies included simultaneous in vitro RhE model and in vivo testing of round robin polymer samples and the results of dual in vitro/in vivo testing of currently marketed medical device components/materials. Our results show for the first time that for both pure chemicals and medical device extracts the intracutaneous rabbit test is more sensitive to detect irritant activity than the rabbit skin patch test. The studies showed that the RhE models produced results that were essentially equivalent to those from the intracutaneous rabbit skin irritation test. Therefore, it is concluded that RhE in vitro models are acceptable replacements for the in vivo rabbit intracutaneous irritation test for evaluating the irritant potential of medical devices.


Subject(s)
Animal Testing Alternatives , Epidermis/drug effects , Equipment and Supplies/adverse effects , Irritants/toxicity , Skin Irritancy Tests/methods , Administration, Topical , Animals , Female , Heptanoic Acids/toxicity , Humans , In Vitro Techniques , Injections, Intradermal , Lactic Acid/toxicity , Male , Rabbits , Reproducibility of Results
19.
Toxicol In Vitro ; 69: 104962, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32781017

ABSTRACT

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.


Subject(s)
Epidermal Cells/drug effects , Epidermis/drug effects , Irritants/toxicity , Skin Irritancy Tests/methods , Animal Testing Alternatives , Disulfides/toxicity , Epidermal Cells/pathology , Epidermis/pathology , Glycolates/toxicity , Humans , Hydrocarbons, Halogenated/toxicity , Hydroxides/toxicity , Phthalic Acids/toxicity , Potassium Compounds/toxicity , Salicylates/toxicity
20.
Regul Toxicol Pharmacol ; 117: 104725, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32768665

ABSTRACT

We conducted a me-too validation study to confirm the reproducibility, reliability, and predictive capacity of KeraSkin™ skin irritation test (SIT) as a me-too method of OECD TG 439. With 20 reference chemicals, within-laboratory reproducibility (WLR) of KeraSkin™ SIT in the decision of irritant or non-irritant was 100%, 100%, and 95% while between-laboratory reproducibility (BLR) was 100%, which met the criteria of performance standard (PS, WLR≥90%, BLR≥80%). WLR and BLR were further confirmed with intra-class correlation (ICC, coefficients >0.950). WLR and BLR in raw data (viability) were also shown with a scatter plot and Bland-Altman plot. Comparison with existing VRMs with Bland-Altman plot, ICC and kappa statistics confirmed the compatibility of KeraSkin™ SIT with OECD TG 439. The predictive capacity of KeraSkin™ SIT was estimated with 20 reference chemicals (the sensitivity of 98.9%, the specificity of 70%, and the accuracy of 84.4%) and additional 46 chemicals (for 66 chemicals [20 + 46 chemicals, the sensitivity, specificity and accuracy: 95.2%, 82.2% and 86.4%]). The receiver operating characteristic (ROC) analysis suggested a potential improvement of the predictive capacity, especially sensitivity, when changing cut-off (50% → 60-75%). Collectively, the me-too validation study demonstrated that KeraSkin™ SIT can be a new me-too method for OECD TG 439.


Subject(s)
Epidermis/drug effects , Guideline Adherence/standards , Irritants/toxicity , Models, Biological , Organisation for Economic Co-Operation and Development/standards , Skin Irritancy Tests/standards , Epidermis/metabolism , Epidermis/pathology , Humans , Irritants/metabolism , Skin Irritancy Tests/methods
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