RESUMEN
OBJECTIVE: Exploring the effects of age on microbial community structure and understanding the effects of chronological ageing as well as sun exposure on microbial community diversity. METHOD: The microbial characteristics of the facial skin of 98 adult women aged 18-70 years were studied using 16S rRNA gene sequencing, and differences based on age and reported sun exposure were assessed. RESULTS: The cheek skin's bacterial diversity and richness increased with age. The relative abundance of Cutibacterium decreased with age, while the relative abundance of Corynebacterium, Anaerococcus, Paracoccus, Micrococcus, Kocuria, Kytococcus, and Chryseobacterium increased. In addition, an increase in Micrococcus and a decrease in Cutibacterium were observed in volunteers with more than 2 h of daily sun exposure compared to volunteers with <2 h of daily sun exposure. Under low-sunlight conditions, Cutibacterium was more prevalent in the youth group, and Corynebacterium, Anaerococcus, and Kytococcus were more prevalent in the older group. CONCLUSION: The diversity and composition of the bacterial community on the cheeks are affected by age and extrinsic factors (sun exposure) may also play a role in this.
OBJECTIF: Étudier les effets de l'âge sur la structure de la communauté microbienne et comprendre les effets du vieillissement chronologique ainsi que de l'exposition au soleil sur la diversité de la communauté microbienne. MÉTHODE: Les caractéristiques microbiennes de la peau du visage de 98 femmes adultes âgées de 18 à 70 ans ont été étudiées à l'aide du séquençage génétique de l'ARNr 16S, et les différences basées sur l'âge et l'exposition au soleil rapportée ont été évaluées. RÉSULTAT: La diversité et la richesse bactériennes de la peau des joues ont augmenté avec l'âge. L'abondance relative de Cutibacterium a diminué avec l'âge, tandis que l'abondance relative de Corynebacterium, Anaerococcus, Paracoccus, Micrococcus, Kocuria, Kytococcus et Chryseobacterium a augmenté. De plus, une augmentation de Micrococcus et une diminution de Cutibacterium ont été observées chez des volontaires ayant été exposés au soleil pendant plus de 2 heures par jour par rapport à des volontaires ayant été exposés au soleil pendant moins de 2 heures par jour. Dans des conditions de faible luminosité, Cutibacterium était plus prévalent dans le bras des personnes jeunes, et Corynebacterium, Anaerococcus et Kytococcus étaient plus prévalents dans le bras des personnes plus âgées. CONCLUSION: La diversité et la composition de la communauté bactérienne sur les joues sont affectées par l'âge et des facteurs extrinsèques (exposition au soleil) peuvent également y jouer un rôle.
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Over the last decade, research into methodologies to identify skin sensitization hazards has led to the adoption of several non-animal methods as OECD test guidelines. However, predictive accuracy beyond the chemical domains of the individual validation studies remains largely untested. In the present study, skin sensitization test results from in vitro and in chemico methods for 12 plant extracts and 15 polymeric materials are reported and compared to available in vivo skin sensitization data. Eight plant extracts were tested in the DPRA and h-CLAT, with the 2 out of 3 approach resulting in a balanced accuracy of 50%. The balanced accuracy for the 11 plant extracts assessed in the SENS-IS was 88%. Excluding 5 polymers inconclusive in vitro, the remainder, assessed using the 2 out of 3 approach, resulted in 63% balanced accuracy. The SENS-IS method, excluding one polymeric material due to technical inapplicability, showed 68% balanced accuracy. Although based on limited numbers, the results presented here indicate that some substance subgroups may not be in the applicability domains of the method used and careful analysis is required before positive or negative results can be accepted.
Asunto(s)
Dermatitis Alérgica por Contacto , Animales , Alternativas a las Pruebas en Animales/métodos , Polímeros/toxicidad , PielRESUMEN
In analogy to the periodic system that groups elements by their similarity in structure and chemical properties, the hazard of chemicals can be assessed in groups having similar structures and similar toxicological properties. Here we review case studies of chemical grouping strategies that supported the assessment of hazard, exposure, and risk to human health. By the EU-REACH and the US-TSCA New Chemicals Program, structural similarity is commonly used as the basis for grouping, but that criterion is not always adequate and sufficient. Based on the lessons learned, we derive ten principles for grouping, including: transparency of the purpose, criteria, and boundaries of the group; adequacy of methods used to justify the group; and inclusion or exclusion of substances in the group by toxicological properties. These principles apply to initial grouping to prioritize further actions as well as to definitive grouping to generate data for risk assessment. Both can expedite effective risk management.
RESUMEN
Four years on since the last cross sector workshop, experience of the practical application and interpretation of several non-animal assays that contribute to the predictive identification of skin sensitisers has begun to accumulate. Non-animal methods used for hazard assessments increasingly are contributing to the potency sub-categorisation for regulatory purposes. However, workshop participants generally supported the view that there remained a pressing need to build confidence in how information from multiple methods can be combined for classification, sub-categorisation and potency assessment. Furthermore, the practical experience gained over the last few years, highlighted the overall high potential value of using the newly validated methods and testing strategies, but also that limitations for certain substance/product classes may become evident with further use as had been the case with other new regulatory methods. As the available information increases, review of the data and collated experience could further determine strengths and limitations leading to more confidence in their use. Finally, the need for a substantial and universally accepted dataset of non-sensitisers and substances of different sensitising potencies, based on combined human and in vivo animal data for validation of methods and test strategies was re-emphasised.
Asunto(s)
Alternativas a las Pruebas en Animales , Congresos como Asunto , Proyectos de Investigación/normas , Piel/efectos de los fármacos , Pruebas de Toxicidad/normas , Conjuntos de Datos como Asunto , Europa (Continente) , Piel/inmunología , Pruebas Cutáneas/métodos , Pruebas Cutáneas/normasRESUMEN
Because of ethical and regulatory reasons, several nonanimal test methods to assess the skin sensitization potential of chemicals have been developed and validated. In contrast to in vivo methods, they lack or provide limited metabolic capacity. For this reason, identification of pro-haptens but also pre-haptens, which require molecular transformations to gain peptide reactivity, is a challenge for these methods. In this study, 27 pre- and pro-haptens were tested using nonanimal test methods. Of these, 18 provided true positive results in the direct peptide reactivity assay (DPRA; sensitivity of 67%), although lacking structural alerts for direct peptide reactivity. The reaction mechanisms leading to peptide depletion in the DPRA were therefore elucidated using mass spectrometry. Hapten-peptide adducts were identified for 13 of the 18 chemicals indicating that these pre-haptens were activated and that peptide binding occurred. Positive results for five of the 18 chemicals can be explained by dipeptide formations or the oxidation of the sulfhydryl group of the peptide. Nine of the 27 chemicals were tested negative in the DPRA. Of these, four yielded true positive results in the keratinocyte and dendritic cell based assays. Likewise, 16 of the 18 chemicals tested positive in the DPRA were also positive in either one or both of the cell-based assays. A combination of DPRA, KeratinoSens, and h-CLAT used in a 2 out of 3 weight of evidence (WoE) approach identified 22 of the 27 pre- and pro-haptens correctly (sensitivity of 81%), exhibiting a similar sensitivity as for directly acting haptens. This analysis shows that the combination of in chemico and in vitro test methods is suitable to identify pre-haptens and the majority of pro-haptens.
Asunto(s)
Alternativas a las Pruebas en Animales , Haptenos/química , Piel/efectos de los fármacos , Cromatografía Líquida de Alta Presión , Espectrometría de Masas , Péptidos/químicaRESUMEN
In general, no single non-animal method can cover the complexity of any given animal test. Therefore, fixed sets of in vitro (and in chemico) methods have been combined into testing strategies for skin and eye irritation and skin sensitisation testing, with pre-defined prediction models for substance classification. Many of these methods have been adopted as OECD test guidelines. Various testing strategies have been successfully validated in extensive in-house and inter-laboratory studies, but they have not yet received formal acceptance for substance classification. Therefore, under the European REACH Regulation, data from testing strategies can, in general, only be used in so-called weight-of-evidence approaches. While animal testing data generated under the specific REACH information requirements are per se sufficient, the sufficiency of weight-of-evidence approaches can be questioned under the REACH system, and further animal testing can be required. This constitutes an imbalance between the regulatory acceptance of data from approved non-animal methods and animal tests that is not justified on scientific grounds. To ensure that testing strategies for local tolerance testing truly serve to replace animal testing for the REACH registration 2018 deadline (when the majority of existing chemicals have to be registered), clarity on their regulatory acceptance as complete replacements is urgently required.
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Alternativas a las Pruebas en Animales , Dermatitis por Contacto , Sustancias Peligrosas/toxicidad , Pruebas de Toxicidad/normas , Animales , Unión Europea , Oftalmopatías/inducido químicamente , Lesiones Oculares/inducido químicamente , Legislación de Medicamentos , Enfermedades de la Piel/inducido químicamenteRESUMEN
In the two years since the last workshop report, the environment surrounding the prediction of skin sensitisation hazards has experienced major change. Validated non-animal tests are now OECD Test Guidelines. Accordingly, the recent cross sector workshop focused on how to use in vitro data for regulatory decision-making. After a review of general approaches and six case studies, there was broad consensus that a simple, transparent stepwise process involving non-animal methods was an opportunity waiting to be seized. There was also strong feeling the approach should not be so rigidly defined that assay variations/additional tests are locked out. Neither should it preclude more complex integrated approaches being used for other purposes, e.g. potency estimation. All agreed the ultimate goal is a high level of protection of human health. Thus, experience in the population will be the final arbiter of whether toxicological predictions are fit for purpose. Central to this is the reflection that none of the existing animal assays is perfect; the non-animal methods should not be expected to be so either, but by integrated use of methods and all other relevant information, including clinical feedback, we have the opportunity to continue to improve toxicology whilst avoiding animal use.
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Alternativas a las Pruebas en Animales/métodos , Cosméticos/toxicidad , Educación/métodos , Informe de Investigación , Piel/efectos de los fármacos , Alternativas a las Pruebas en Animales/tendencias , Animales , Cosméticos/administración & dosificación , Cosméticos/farmacocinética , Dermatitis Alérgica por Contacto/metabolismo , Dermatitis Alérgica por Contacto/patología , Educación/tendencias , Europa (Continente) , Finlandia , Humanos , Informe de Investigación/tendencias , Medición de Riesgo/métodos , Medición de Riesgo/tendencias , Piel/metabolismo , Piel/patologíaRESUMEN
The European Partnership for Alternative Approaches to Animal Testing (EPAA) convened a workshop Knowledge sharing to facilitate regulatory decision-making. Fifty invited participants from the European Commission, national and European agencies and bodies, different industry sectors (chemicals, cosmetics, fragrances, pharmaceuticals, vaccines), and animal protection organizations attended the workshop. Four case studies exemplarily revealed which procedures are in place to obtain regulatory acceptance of new test methods in different sectors. Breakout groups discussed the status quo identifying the following facilitators for regulatory acceptance of alternatives to animal testing: Networking and communication (including cross-sector collaboration, international cooperation and harmonization); involvement of regulatory agencies from the initial stages of test method development on; certainty on prerequisites for test method acceptance including the establishment of specific criteria for regulatory acceptance. Data sharing and intellectual property issues affect many aspects of test method development, validation and regulatory acceptance. In principle, all activities should address replacement, reduction and refinement methods (albeit animal testing is generally prohibited in the cosmetics sector). Provision of financial resources and education support all activities aiming at facilitating the acceptance and use of alternatives to animal testing. Overall, workshop participants recommended building confidence in new methodologies by applying and gaining experience with them.
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Alternativas a las Pruebas en Animales/métodos , Pruebas de Toxicidad/métodos , Animales , Cosméticos/química , Toma de Decisiones , Industrias/métodos , Cooperación InternacionalRESUMEN
Sensitization, the prerequisite event in the development of allergic contact dermatitis, is a key parameter in both hazard and risk assessments. The pathways involved have recently been formally described in the OECD adverse outcome pathway (AOP) for skin sensitization. One single non-animal test method will not be sufficient to fully address this AOP and in many cases the use of a battery of tests will be necessary. A number of methods are now fully developed and validated. In order to facilitate acceptance of these methods by both the regulatory and scientific communities, results of the single test methods (DPRA, KeratinoSens, LuSens, h-CLAT, (m)MUSST) as well for a the simple '2 out of 3' ITS for 213 substances have been compiled and qualitatively compared to both animal and human data. The dataset was also used to define different mechanistic domains by probable protein-binding mechanisms. In general, the non-animal test methods exhibited good predictivities when compared to local lymph node assay (LLNA) data and even better predictivities when compared to human data. The '2 out of 3' prediction model achieved accuracies of 90% or 79% when compared to human or LLNA data, respectively and thereby even slightly exceeded that of the LLNA.
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Alternativas a las Pruebas en Animales/métodos , Bases de Datos Factuales , Fármacos Dermatológicos/toxicidad , Piel/efectos de los fármacos , Animales , Línea Celular , Humanos , Ratones , Piel/patología , Células U937RESUMEN
Regulatory CD4(+)CD25(+) T cells are important in suppressing immune responses. The requirements for the maintenance of peripheral CD4(+)CD25(+) T cells remain incompletely understood. Receptor activator of NF-kappaB (RANK) and its ligand (RANKL; also known as CD254, OPGL and TRANCE) are key regulators of bone remodeling, mammary gland formation, lymph node development and T-cell/dendritic cell communication. Here we report that RANKL is expressed in keratinocytes of the inflamed skin. RANKL overexpression in keratinocytes resulted in functional alterations of epidermal dendritic cells and systemic increases of regulatory CD4(+)CD25(+) T cells. Thus, epidermal RANKL expression can change dendritic cell functions to maintain the number of peripheral CD4(+)CD25(+) regulatory T cells. Epidermal RANKL mediated ultraviolet-induced immunosuppression and overexpression of epidermal RANKL suppressed allergic contact hypersensitivity responses and the development of systemic autoimmunity. Therefore, environmental stimuli at the skin can rewire the local and systemic immune system by means of RANKL.
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Células Dendríticas/fisiología , Epidermis/fisiología , Ligando RANK/fisiología , Linfocitos T Reguladores/citología , Animales , Autoinmunidad , Recuento de Células , Células Epidérmicas , Epidermis/metabolismo , Tolerancia Inmunológica/efectos de la radiación , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Transgénicos , Ligando RANK/genética , Ligando RANK/metabolismo , Rayos UltravioletaRESUMEN
Skin corrosion or irritation refers to the production of irreversible or reversible damage to the skin following the application of a test substance, respectively. Traditionally, hazard assessments are conducted using the in vivo Draize skin test, but recently in vitro tests using reconstructed human epidermis (RhE) models have gained regulatory acceptance. In this study, skin corrosion (SCT) and irritation tests (SIT) using a RhE model were implemented to reduce the number of in vivo tests required by regulatory bodies. One hundred and thirty-four materials were tested from a wide range of substance classes included 46 agrochemical formulations. Results were assessed according to UN GHS, EU-CLP, ANVISA and US EPA classification schemes. There was high correlation between the two in vitro tests. Assessment of the SCT sensitivity was not possible due to the limited number of corrosives in the data set; SCT specificity and accuracy were 89% for all classification systems. Accuracy (6376%) and sensitivity (5367%) were low in the SIT. Specificity and concordance for agrochemical formulations alone in both the SCT and SIT were comparable to the values for the complete data set (SCT: 91% vs. 89% specificity, 91% vs. 89% accuracy and SIT: 6488% vs. 7085% specificity, 5675% vs. 6376% accuracy).
Asunto(s)
Irritantes/toxicidadRESUMEN
In a previous EPAA-Cefic LRI workshop in 2011, issues surrounding the use and interpretation of results from the local lymph node assay were addressed. At the beginning of 2013 a second joint workshop focused greater attention on the opportunities to make use of non-animal test data, not least since a number of in vitro assays have progressed to an advanced position in terms of their formal validation. It is already recognised that information produced from non-animal assays can be used in regulatory decision-making, notably in terms of classifying a substance as a skin sensitiser. The evolution into a full replacement for hazard identification, where the decision is not to classify, requires the generation of confidence in the in vitro alternative, e.g. via formal validation, the existence of peer reviewed publications and the knowledge that the assay(s) are founded on key elements of the Adverse Outcome Pathway for skin sensitisation. It is foreseen that the validated in vitro assays and relevant QSAR models can be organised into formal testing strategies to be applied for regulatory purposes by the industry. To facilitate progress, the European Partnership for Alternative Approaches to animal testing (EPAA) provided the platform for cross-industry and regulatory dialogue, enabling an essential and open debate on the acceptability of an in vitro based integrated strategy. Based on these considerations, a follow up activity was agreed upon to explore an example of an Integrated Testing Strategy for skin sensitisation hazard identification purposes in the context of REACH submissions.
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Alternativas a las Pruebas en Animales , Dermatitis Alérgica por Contacto/etiología , Regulación Gubernamental , Sustancias Peligrosas/toxicidad , Piel/efectos de los fármacos , Alternativas a las Pruebas en Animales/legislación & jurisprudencia , Alternativas a las Pruebas en Animales/métodos , Alternativas a las Pruebas en Animales/tendencias , Animales , Congresos como Asunto , Unión Europea , Sustancias Peligrosas/química , Humanos , Cooperación InternacionalRESUMEN
Contact allergies are complex diseases, and it is estimated that 15-20 % of the general population suffers from contact allergy, with increasing prevalence. Evaluation of the sensitization potential of a substance is usually carried out in animal models. Nowadays, there is much interest in reducing and ultimately replacing current animal tests. Furthermore, as of 2013, the EU has posed a ban on animal testing of cosmetic ingredients that includes skin sensitization. Therefore, predictive and robust in vitro tests are urgently needed. In order to establish alternatives to animal testing, the in vitro tests must mimic the very complex interactions between the sensitizing chemical and the different parts of the immune system. This review article summarizes recent efforts to develop in vitro tests for predicting skin sensitizers. Cell-based assays, in chemico methods and, to a lesser extent, in silico methods are presented together with a discussion of their current status. With considerable progress having been achieved during the last years, the rationale today is that data from different non-animal test methods will have to be combined in order to obtain reliable hazard and potency information on potential skin sensitizers.
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Alternativas a las Pruebas en Animales , Dermatitis Alérgica por Contacto/etiología , Pruebas de Irritación de la Piel/métodos , Piel/efectos de los fármacos , Animales , Técnicas de Cultivo de Célula , Células Cultivadas , Simulación por Computador , Dermatitis Alérgica por Contacto/genética , Dermatitis Alérgica por Contacto/inmunología , Dermatitis Alérgica por Contacto/patología , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Modelos Animales , Modelos Biológicos , Medición de Riesgo , Factores de Riesgo , Piel/inmunología , Piel/patologíaRESUMEN
As toxicology in the 21st century progresses towards a future which aims at avoiding the use of in vivo testing, the endpoint of skin sensitisation can now be found in the front line. Accordingly, it was appropriate for several industry sectors to meet and review what has been learned from the currently most widely used in vivo method, the local lymph node assay (LLNA), and to consider the status of progress as we attempt to move beyond that test. No toxicology test is perfect, an experience brought into focus by issues of false positives and, to a lesser extent, false negatives in the LLNA. Use of weight of evidence arguments for classification and labelling, as well as for risk assessment was emphasised and it was also noted that a sufficient body of evidence now exists for conduct of methods other than the LLNA for carefully defined chemical classes. In terms of in vitro alternatives, progress towards methods which will deliver mainly hazard identification is being made, with some entering the final stages of validation, whereby (Q)SAR tools still need improvement to be used on a large scale in practise. As various other challenges also remain, e.g. testing lipophilic substances, as well as the development of non-animal methods which deliver reliable information on potency for risk assessment, these will remain a topic for continuing research and development.
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Alérgenos/toxicidad , Dermatitis Alérgica por Contacto/etiología , Inmunización/métodos , Ensayo del Nódulo Linfático Local , Enfermedades de la Piel/inducido químicamente , Alérgenos/química , Alérgenos/inmunología , Alternativas a las Pruebas en Animales , Animales , Dermatitis Alérgica por Contacto/patología , Reacciones Falso Negativas , Reacciones Falso Positivas , Relación Estructura-Actividad Cuantitativa , Medición de Riesgo , Enfermedades de la Piel/inmunología , Pruebas de ToxicidadRESUMEN
Skin corrosion or irritation refers to the production of irreversible or reversible damage to the skin following the application of a test substance, respectively. Traditionally, hazard assessments are conducted using the in vivo Draize skin test, but recently in vitro tests using reconstructed human epidermis (RhE) models have gained regulatory acceptance. In this study, skin corrosion (SCT) and irritation tests (SIT) using a RhE model were implemented to reduce the number of in vivo tests required by regulatory bodies. One hundred and thirty-four materials were tested from a wide range of substance classes included 46 agrochemical formulations. Results were assessed according to UN GHS, EU-CLP, ANVISA and US EPA classification schemes. There was high correlation between the two in vitro tests. Assessment of the SCT sensitivity was not possible due to the limited number of corrosives in the data set; SCT specificity and accuracy were 89% for all classification systems. Accuracy (63-76%) and sensitivity (53-67%) were low in the SIT. Specificity and concordance for agrochemical formulations alone in both the SCT and SIT were comparable to the values for the complete data set (SCT: 91% vs. 89% specificity, 91% vs. 89% accuracy and SIT: 64-88% vs. 70-85% specificity, 56-75% vs. 63-76% accuracy).
Asunto(s)
Agroquímicos/toxicidad , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Irritantes/toxicidad , Piel/efectos de los fármacos , Animales , Humanos , Irritantes/clasificación , Conejos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Piel/metabolismo , Piel/patología , Pruebas de Irritación de la Piel/métodosRESUMEN
Allergic contact dermatitis is a common skin disease and is elicited by repeated skin contact with an allergen. In the regulatory context, currently only data from animal experiments are acceptable to assess the skin sensitizing potential of substances. Animal welfare and EU Cosmetic Directive/Regulation call for the implementation of animal-free alternatives for safety assessments. The mechanisms that trigger skin sensitization are complex and various steps are involved. Therefore, a single in vitro method may not be able to accurately assess this endpoint. Non-animal methods are being developed and validated and can be used for testing strategies that ensure a reliable prediction of skin sensitization potentials. In this study, the predictivities of four in vitro assays, one in chemico and one in silico method addressing three different steps in the development of skin sensitization were assessed using 54 test substances of known sensitizing potential. The predictivity of single tests and combinations of these assays were compared. These data were used to develop an in vitro testing scheme and prediction model for the detection of skin sensitizers based on protein reactivity, activation of the Keap-1/Nrf2 signaling pathway and dendritic cell activation.
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Alérgenos/toxicidad , Alternativas a las Pruebas en Animales/métodos , Bioensayo/métodos , Dermatitis Alérgica por Contacto/etiología , Animales , Humanos , Reproducibilidad de los Resultados , Pruebas de Irritación de la PielRESUMEN
Extensive research has been conducted over the past decades to develop alternatives to the rabbit eye irritation test (Draize test) used in a regulatory context to assess eye irritation potentials. Although no single in vitro test has emerged as being completely acceptable for full replacement, various tests are considered to be suitable and are regularly used to assess certain aspects. Amongst these, the Hen's Egg Test Chorioallantoic Membrane (HET-CAM) has gained regulatory acceptance in various countries to classify severe eye irritants. In this retrospective study, historical eye irritation data (in vivo and in vitro) from 137 samples (approx. 75% non-irritants; 25% (severe) irritants) tested both in the HET-CAM and Draize eye test was compared with regard to the predicted eye irritation classes under the GHS and the traditional EU classification system (DSD).The overall concordance was in the range of 80-90%. A high specificity (96-98%, depending on the classification system and the chosen discrimination) but rather low sensitivity (48-65%) was observed. The study indicates that HET-CAM results are useful as part of weight-of-evidence assessments or in tiered approaches to assess eye irritation potentials rather than as stand-alone classification method.
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Membrana Corioalantoides/efectos de los fármacos , Bases de Datos Factuales/normas , Irritantes/clasificación , Irritantes/toxicidad , Alternativas a las Pruebas en Animales/métodos , Alternativas a las Pruebas en Animales/normas , Animales , Embrión de Pollo , Membrana Corioalantoides/patología , Interpretación Estadística de Datos , Irritantes/administración & dosificación , Conejos , Estudios RetrospectivosRESUMEN
An integral part of hazard and safety assessments is the estimation of a chemical's potential to cause skin sensitization. Currently, only animal tests (OECD 406 and 429) are accepted in a regulatory context. Nonanimal test methods are being developed and formally validated. In order to gain more insight into the responses induced by eight exemplary surfactants, a battery of in vivo and in vitro tests were conducted using the same batch of chemicals. In general, the surfactants were negative in the GPMT, KeratinoSens and hCLAT assays and none formed covalent adducts with test peptides. In contrast, all but one was positive in the LLNA. Most were rated as being irritants by the EpiSkin assay with the additional endpoint, IL1-alpha. The weight of evidence based on this comprehensive testing indicates that, with one exception, they are non-sensitizing skin irritants, confirming that the LLNA tends to overestimate the sensitization potential of surfactants. As results obtained from LLNAs are considered as the gold standard for the development of new nonanimal alternative test methods, results such as these highlight the necessity to carefully evaluate the applicability domains of test methods in order to develop reliable nonanimal alternative testing strategies for sensitization testing.
Asunto(s)
Irritantes/farmacología , Ensayo del Nódulo Linfático Local , Piel/efectos de los fármacos , Tensoactivos/farmacología , Animales , Línea Celular , Proliferación Celular/efectos de los fármacos , Glucósidos/metabolismo , Cobayas , Humanos , Interleucina-1alfa/inmunología , Interleucina-1alfa/metabolismo , Irritantes/toxicidad , Ratones , Ratones Endogámicos CBA , Péptidos/química , Relación Estructura-Actividad Cuantitativa , Medición de Riesgo/métodos , Pruebas de Irritación de la Piel/métodos , Estadística como Asunto/métodos , Tensoactivos/toxicidadRESUMEN
The Local Lymph Node Assay (LLNA) is the preferred test for the identification of skin-sensitizing potentials of chemicals in Europe and is also the first choice method within REACH. In the formal validation, only a very few surfactant chemicals were evaluated and SDS was identified as a false positive. In this study, 10 nonionic sugar lipid surfactants were tested in an LLNA, guinea pig maximization test (GPMT) and human repeated insult patch test. Of the 10 surfactants tested in the LLNA, 5 showed stimulation indices above 3.0. Three of five positive reactions were concomitant with signs of skin irritation indicated by an increase in ear thickness. In the GPMT, all test products were classified as nonsensitizers. In human volunteers, no skin reactions suggestive of sensitization were reported. In conclusion, these results are indicative of the LLNA overestimating sensitization potentials for this category of chemicals. This may in part be due to irritant effects generated by these surfactants. Until suitable nonanimal alternative tests obtain regulatory acceptance, use of other tests, e.g. GPMTs, may in cases be justified. Results such as these need be taken into account when developing nonanimal alternative methods to ensure reliable data sets for method validation purposes.
Asunto(s)
Ensayo del Nódulo Linfático Local , Pruebas de Irritación de la Piel/métodos , Tensoactivos/toxicidad , Animales , Cobayas , Humanos , Ratones , Ratones Endogámicos CBA , Pruebas del Parche/métodos , Pruebas Cutáneas/métodos , Especificidad de la Especie , Tensoactivos/químicaRESUMEN
BACKGROUND: Development of cosmetic products and household detergents necessitates comparative study designs to assess the skin tolerance of products. In initial tests, the epicutaneous patch test for irritation is widely used. OBJECTIVES: This study was conducted to develop a protocol that would facilitate a comparison of results obtained when tests are conducted by different laboratories. METHODS: 'In-house' and standardized patch test protocols were used to assess irritation potentials of surfactant-based products in intra- and interlaboratory studies using defined surfactant samples. RESULTS: The various in-house protocols tested did not consistently produce equivalent results. In order to develop a study design that yields comparable results, various factors were identified and adjusted. The standardized study protocol includes occlusive application of 70 microl of the test substance to the back of 30 subjects, defined reading times and schemes, assessments based mainly on erythema, and inclusion of sodium laureth sulfate and sodium dodecyl sulfate as positive controls as well as water as a negative control. CONCLUSIONS: Use of the standardized protocol and training of assessors improved the reliability and consistency of results whereby the irritation potentials of the references and test samples were ranked similarly by the laboratories.