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Query: UMLS:C0152030 (skin irritation)
 2,146 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In view of the increasing need to identify non-animal tests able to predict acute skin irritation of chemicals, the European Centre for the Validation of Alternative Methods (ECVAM) focused on the evaluation of appropriate in vitro models. In vitro tests should be capable of discriminating between irritant (I) chemicals (EU risk: R38) and non-irritant (NI) chemicals (EU risk: "no classification"). Since major in vivo skin irritation assays rely on visual scoring, it is still a challenge to correlate in vivo clinical signs with in vitro biochemical measurements. Being particularly suited to test raw materials or chemicals with a wide variety of physical properties, in vitro skin models resembling in vivo human skin were involved in prevalidation processes. Among many other factors, cytotoxicity is known to trigger irritation processes, and can therefore be a first common event for irritants. A refined protocol (protocol 15min-18hours) for the EPISKIN model had been proposed for inclusion in the ECVAM formal validation study. A further improvement on this protocol, mainly based on a post-treatment incubation period of 42 hours (protocol 15min-42hours), the optimised protocol, was applied to a set of 48 chemicals. The sensitivity, specificity and accuracy with the MTT assay-based prediction model (PM) were 85%, 78.6% and 81.3% respectively, with a low rate of false negatives (12%). The improved performance of this optimised protocol was confirmed by a higher robustness (homogeneity of individual responses) and a better discrimination between the I and NI classes. To improve the MTT viability-based PM, the release of a membrane damage marker, adenylate kinase (AK), and of cytokines IL-1alpha and IL-8 were also investigated. Combining these endpoints, a simple two-tiered strategy (TTS) was developed, with the MTT assay as the first, sort-out, stage. This resulted in a clear increase in sensitivity to 95%, and a fall in the false-positive rate (to 4.3%), thus demonstrating its usefulness as a "decision-making" tool. The optimised protocol proved, both by its higher performances and by its robustness, to be a good candidate for the validation process, as well as a potential alternative method for assessing acute skin irritation.
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PMID:The in vitro skin irritation of chemicals: optimisation of the EPISKIN prediction model within the framework of the ECVAM validation process. 1618 3

Since it is of high importance to establish the skin irritation potential of industrial chemicals, toxicologists developed tests on various skin models. Most test data come from the rabbit Draize test, but its reproducibility is questionable. Some human in vivo test data exist, but they concern only few compounds. The emergence of new tools such as reconstituted human skin tissues offers a promising future to alternative methods. We describe here two in vitro skin irritation test protocols performed on reconstituted human epidermis. One is a direct topical application test and the other an in vitro patch test. Both protocols were performed using multiple endpoint analysis including cell viability (MTT reduction), histology, and IL-1alpha release. Fifty chemicals were tested: 20 compounds were used in the ECVAM pre-validation study and 30 products were previously tested in a human in vivo patch test. These in vitro skin irritation tests have not only the advantages of enhanced convenience and of reduced costs, but a good reproducibility is observed by endpoint, and by compound. A prediction model is proposed to classify the chemicals as irritant or non-irritant, and the results are compared to available rabbit and human data. We do not wish to overgeneralize from these 50 compounds; but, instead suggest that this data set be extensively extended to include chemicals of varying physico-chemical properties.
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PMID:In vitro skin irritation testing on reconstituted human epidermis: reproducibility for 50 chemicals tested with two protocols. 1622 85

Arginine-derivative surfactants constitute a novel class of surfactants, which can be regarded as an alternative to conventional surfactants. Prior to human exposure, it is necessary to assess their irritation potential. The classical in vivo evaluation of the irritancy potential via the Draize test has been extensively criticized. In that regard, a great number of in vitro alternatives have been developed. Erythrocytes were chosen as the target cells for eye irritation assessment and hemolysis and hemoglobin denaturation were selected as appropriate endpoints. For skin irritancy assessment, the keratinocyte cell line NCTC 2544 was used and different in vitro endpoints were measured: two cytotoxicity assays (NRU and MTT) and the synthesis of the proinflammatory cytokine IL-1alpha. The eye and skin Draize tests were also performed for comparative purposes. The results point out that, according to in vivo and in vitro assays, the new arginine-derivative surfactants have lower eye and skin irritation potential than the synthetic surfactant SDS. Furthermore, in vitro methods were also able to detect differences in irritancy among the new surfactants not noticeable by the Draize tests, indicating that in vitro methods can be more sensitive than the in vivo test, offering the opportunity to detect subtle differences in irritancy.
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PMID:Evaluation of eye and skin irritation of arginine-derivative surfactants using different in vitro endpoints as alternatives to the in vivo assays. 1647 49

New concepts of the horny layer as a metabolically active part of the epidermal permeability barrier elicited a re-evaluation of conventional mechanisms of occupational skin protection. Both skin protection products and noxae must penetrate the horny layer of the skin to be effective. The isolated perfused bovine udder skin (BUS) model reflects the natural penetration pattern; hence skin irritation, penetration and absorption can be investigated simultaneously. Using whole skin biopsies the degree of irritation in untreated (control), treated and pre-treated skin is measured by assessing the irritancy (PGE2-concentration) and cytotoxicity (MTT assay) after the exposure period of 0.5 h, 1.0 h and 5.0 h. Two types of skin protection studies were reported. One was a laboratory study using the water-soluble sodiumlaurylsulphate (10%, 15%) as noxa. The other study was initiated by a severely skin irritating water-soluble coolant (approx. 5%). This well documented case occurred in a metal working plant. In both studies different degrees of protective potential against the model noxae SLS and the coolant could be observed.
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PMID:[Bovine udder skin (BUS): testing of skin compatibility and skin protection]. 1668 83

Lysine derivative surfactants are a class of amino acid-based surfactants synthesized as lecithin analogues that deserve particular attention because of their low toxicity and high biocompatibility. To complete the toxicological profile of these surfactants, IL-1 alpha production (cell-associated and release to the culture medium) was determined as an in vitro method for predicting skin irritation. In addition, an MTT assay was used as a viability marker in keratinocytes NCTC 2544. Keratinocytes are a biologically relevant target for developing in vitro techniques to assess skin irritants: moreover, they are the principal source of the proinflammatory cytokine IL-1 alpha in the epidermis. Lysine derivatives proved to be less potent in stimulating IL-1 alpha synthesis and induced a lower release of this cytokine into the culture medium when compared to the anionic surfactant sodium dodecyl sulfate. Due to their low irritancy potential, lysine-based surfactants may offer promising applications in pharmaceutical and cosmetic preparations.
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PMID:Determination of interleukin-1alpha in human NCTC 2544 keratinocyte cells as a predictor of skin irritation from lysine-based surfactants. 1699 34

Although skin and respiratory sensitizing properties of platinum compounds have been proved in humans and mice, little is known about signal transduction pathways leading to cytokine production in the induction phase. It is generally assumed that induction of skin sensitization, but not skin irritation, is associated with a rapid increase in the IL-1beta mRNA expression. In this study, IL-1beta expression and a role of mitogen-activated protein kinases (MAPKs) in this process were investigated in murine macrophages J774A.1 exposed to four platinum compounds. Potassium tetrachloroplatinate (K(2)PtCl(4); TCPP), ammonium tetrachloroplatinate ((NH(4))(2)PtCl(4); TCPA), ammonium hexachloroplatinate ((NH(4))(2)PtCl(6); HCPA) showed a very similar range of cytotoxic concentrations (IC(50) values: 238 microM+/-30; 269 microM+/-39 and 245 microM+/-31, respectively) as assessed in the 24-h MTT reduction test. Cytotoxicity of cis-diammineplatinum dichloride (cisplatin) was considerably higher (IC(50) of 23 microM+/-4). While increased expression of IL-1beta mRNA was observed in the macrophages exposed to each test compound, IL-1beta protein production was detected in cell lysates after treatment with TCPP, TCPA and HCPA for 24h (concentration range of 150-350 microM) as well as for 2h (450-650 microM). The treatment with each compound resulted in the phosphorylation of both p38 MAPK and ERK 1/2 (p44/42). Blocking the activation of p38 MAPK as well as ERK 1/2 with specific inhibitors (SB203580 and U0126, respectively) down-regulated the IL-1beta expression. Interestingly, the skin irritant sodium dodecyl sulfate did not trigger phosphorylation of these kinases, nor induced IL-1beta production. These data suggest that p38 MAPK and ERK 1/2 play an important role in induction of IL-1beta expression in J774A.1 macrophages exposed to test platinum compounds.
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PMID:Interleukin-1beta expression in murine J774A.1 macrophages exposed to platinum compounds: the role of p38 and ERK 1/2 mitogen-activated protein kinases. 1708 86

Arachidonic acid (AA), a precursor of pro-inflammatory mediators, and its glycerin ester, glyceryl arachidonate (GA), are reportedly used in cosmetic products. In vitro skin penetration of AA and GA and GA's ester hydrolysis was determined in flow-through diffusion cells. AA penetration with human and rat skin was 19.5% and 52.3% of the applied dose respectively, a substantial amount of which remained in the skin at 24h. Similar penetration results were obtained with GA in human skin. However, GA penetration through cultured skin (EpiDerm) was 51% of the applied dose, almost all of which appeared in the receptor fluid. At least 27.8% of GA penetrating skin was hydrolyzed to AA. In vitro methods were used to assess skin irritation in diffusion cells. Skin irritation of AA, sodium lauryl sulfate (SLS), and Tween 80 was determined by changes in transepidermal water loss (TEWL), skin viability (3-(4,5-dimethylthiaxol-2-yl)-2,5-diphenyltetrazolium bromide, MTT, formation), and cytokine release (IL-1alpha). SLS irritation was much less pronounced in an emulsion versus an aqueous vehicle. No significant irritation was observed in vitro from AA in an emulsion. This work predicts that AA would penetrate human skin in vivo and that it could be formed in skin from topically applied GA.
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PMID:Assessment of skin absorption and irritation potential of arachidonic acid and glyceryl arachidonate using in vitro diffusion cell techniques. 1760 15

ECVAM sponsored a formal validation study on three in vitro tests for skin irritation, of which two employ reconstituted human epidermis models (EPISKIN, EpiDerm), and one, the skin integrity function test (SIFT), employs ex vivo mouse skin. The goal of the study was to assess whether the in vitro tests would correctly predict in vivo classifications according to the EU classification scheme, "R38" and "no label" (i.e. non-irritant). 58 chemicals (25 irritants and 33 non-irritants) were tested, having been selected to give broad coverage of physico-chemical properties, and an adequate distribution of irritancy scores derived from in vivo rabbit skin irritation tests. In Phase 1, 20 of these chemicals (9 irritants and 11 non-irritants) were tested with coded identities by a single lead laboratory for each of the methods, to confirm the suitability of the protocol improvements introduced after a prevalidation phase. When cell viability (evaluated by the MTT reduction test) was used as the endpoint, the predictive ability of both EpiDerm and EPISKIN was considered sufficient to justify their progression to Phase 2, while the predictive ability of the SIFT was judged to be inadequate. Since both the reconstituted skin models provided false predictions around the in vivo classification border (a rabbit Draize test score of 2), the release of a cytokine, interleukin-1alpha (IL-1alpha), was also determined. In Phase 2, each human skin model was tested in three laboratories, with 58 chemicals. The main endpoint measured for both EpiDerm and EPISKIN was cell viability. In samples from chemicals which gave MTT assay results above the threshold of 50% viability, IL-1alpha release was also measured, to determine whether the additional endpoint would improve the predictive ability of the tests. For EPISKIN, the sensitivity was 75% and the specificity was 81% (MTT assay only); with the combination of the MTT and IL-1alpha assays, the sensitivity increased to 91%, with a specificity of 79%. For EpiDerm, the sensitivity was 57% and the specificity was 85% (MTT assay only), while the predictive capacity of EpiDerm was not improved by the measurement of IL-1alpha release. Following independent peer review, in April 2007 the ECVAM Scientific Advisory Committee endorsed the scientific validity of the EPISKIN test as a replacement for the rabbit skin irritation method, and of the EpiDerm method for identifying skin irritants as part of a tiered testing strategy. This new alternative approach will probably be the first use of in vitro toxicity testing to replace the Draize rabbit skin irritation test in Europe and internationally, since, in the very near future, new EU and OECD Test Guidelines will be proposed for regulatory acceptance.
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PMID:The ECVAM international validation study on in vitro tests for acute skin irritation: report on the validity of the EPISKIN and EpiDerm assays and on the Skin Integrity Function Test. 1818 67

Testing chemicals for their ability to cause skin irritation is required for all ingredients of products that come into contact with the skin. Here, we describe a potential method for determining the irritant potency of a chemical in vitro and apply the method to two different reconstructed epidermis models which exhibit different barrier properties. Two surfactants: sodium dodecyl sulphate, Triton X100 and two non-surfactants: 2-4-di-nitro-chloro-benzene, cinnamaldehyde were applied topically in a dose response for 24h. Biomarkers IL-1alpha, IL-1RA, IL-8 and MTT were assessed and EC(50) values determined. Variation in barrier properties between the epidermal models led to variation in the extent of penetration of surfactants, but not of non-surfactants which in turn influenced the EC(50) value obtained from surfactants. Furthermore, EC(50) values showed that no single biomarker could be classed as the most sensitive biomarker since biomarker sensitivity differed between the different chemicals studied. However, the ranking of the chemicals in order of strong to weak irritant was the same irrespective of the model used and also independent of the biomarker used (Triton X100>DNCB>SDS>CA). This study describes a method which not only distinguishes an irritant from a non-irritant but which may possibly also be used to determine irritant potency.
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PMID:Potential method to determine irritant potency in vitro - Comparison of two reconstructed epidermal culture models with different barrier competency. 1913 41

Irritant contact dermatitis is the result of an innate inflammatory response of the skin to direct injury. It is caused by a single, repeated or continued application of an irritant, with the source most often being a chemical. Therefore, European regulations require strict screening of all ingredients in consumer products. Until recently, identifying a potential irritant has completely relied on animal testing (for example, Draize test). Besides the ethical problems, both the 7th Amendment to the Cosmetics Directive and Registration, Evaluation and Authorization of Chemicals legislation have stimulated the development of alternative tests for the assessment of potential toxicological effects of substances. This review is aimed at describing current in vitro skin irritation models and the biomarkers used to assess the degree of irritancy of a potential irritant. Four models are described: keratinocyte and fibroblast cultures grown under submerged culture conditions, epidermal equivalents, skin equivalents and freshly isolated skin. Biomarkers such as IL-1alpha, IL-6, IL-8, PGE2, SKALP, HSP70 and kinases are described along with changes in metabolic activity (MTT assay) and cytosolic leakage (lactate dehydrogenase assay). Noticeable is the limited number of genomic and proteomic studies. Such studies have the potential to identify novel biomarkers and to elucidate the mechanism of irritant contact dermatitis.
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PMID:In vitro irritation models and immune reactions. 1918 58


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