The critical review of methodologies and approaches to assess the inherent skin sensitization potential (skin allergies) of chemicals Part II

Anti-Inflammatory and Antioxidant Properties of Physalis alkekengi L. Extracts In Vitro and In Vivo: Potential Application for Skin Care

OBJECTIVE

Inflammatory skin disorders are becoming major issues threatening public health with increasing prevalence. This study was to evaluate the anti-inflammatory, antioxidant, and antisenescent activities of traditional folk medicinal plant, Physalis alkekengi L. extracts to alleviate skin inflammation and its possible mechanisms.

METHODS

Lipopolysaccharides (LPS)-treated murine macrophages RAW264.7 and human skin keratinocytes HaCaT were incubated with the plant extracts, respectively. The production of nitric oxide (NO) was tested by using Griess reagents. The activity of nitric oxide synthase (NOS) was detected through a fluorescence microplate reader. Reactive oxygen species (ROS) production and cell apoptosis were quantified by flow cytometry. The proinflammatory cytokines were measured using ELISA and qRT-PCR. Human skin fibroblasts (HFF-1) were coincubated with D-galactose (D-gal) and the plant extracts. The senescence associated-galactosidase (SA-β-gal) was stained to evaluate cellular senescence. The senescence-associated secretory phenotype (SASP), IL-1β, was measured through ELISA. The mRNA of IL-1α in SLS-stimulated and PGE2 in UV-radiated 3D skin models were detected by qRT-PCR. In vivo ROS production and neutrophil recruitment in CuSO₄-treated zebrafish models were observed by fluorescence microscopy. Inflammation-related factors were measured by qRT-PCR. Results. In vitro, Physalis alkekengi L. significantly reduced NO production, NOS activity, cell apoptosis, transcription of TNF-α, IL-6, IL-1β and ROS production. These plant extracts markedly attenuated SA-β-gal and IL-1β and downregulated the production of IL-1α and PGE2. In vivo, the plant extracts dramatically dampened ROS production, the number of neutrophils, and proinflammatory cytokines.

CONCLUSIONS

Cumulatively, this work systematically demonstrated the anti-inflammatory, antioxidant, and antisenescent properties of Physalis alkekengi L. and proposed the possible roles of Physalis alkekengi L. in inflammatory signaling pathways, providing an effective natural product for the treatment of inflammatory skin disorders.

Skin Sensitization Testing: The Ascendancy of Non-Animal Methods

A century ago, toxicology was an empirical science identifying substance hazards in surrogate mammalian models. Over several decades, these models improved, evolved to reduce animal usage, and recently have begun the process of dispensing with animals entirely. However, despite good hazard identification, the translation of hazards into adequately assessed risks to human health often has presented challenges. Unfortunately, many skin sensitizers known to produce contact allergy in humans, despite being readily identified as such in the predictive assays, continue to cause this adverse health effect. Increasing the rigour of hazard identification is inappropriate. Regulatory action has only proven effective via complete bans of individual substances. Since the problem applies to a broad range of substances and industry categories, and since generic banning of skin sensitizers would be an economic catastrophe, the solution is surprisingly simple—they should be subject to rigorous safety assessment, with the risks thereby managed accordingly. The ascendancy of non-animal methods in skin sensitization is giving unparalleled opportunities in which toxicologists, risk assessors, and regulators can work in concert to achieve a better outcome for the protection of human health than has been delivered by the in vivo methods and associated regulations that they are replacing.

Cosmetic preservative labelling on the Thai market

BACKGROUND

Preservatives are added to cosmetics and other consumer products to prevent microbial growth and product degradation. Many cosmetic preservatives are skin sensitizers and frequent causes of contact dermatitis. The use of preservatives may vary by country and/or region, according to legislation, and may be reflected in differences in the prevalence rates of preservative allergy worldwide.

OBJECTIVE

To examine the type and frequency of preservative use in cosmetics sold in Thai markets in metropolitan Bangkok, Thailand.

METHODS

Preservatives contained in 1000 different cosmetics sold in Thai markets were documented and analysed, based on the labelling of ingredients.

RESULTS

Most of the cosmetic and skincare products sold in Thai markets were international brands, with only a small proportion of cosmetic products being produced in Thailand. International brand cosmetics were more likely to contain non-formaldehyde-releasing preservatives than domestically produced brands. Isothiazolinone-based preservatives, which are responsible for the current increase in the prevalence of contact allergy, were found at a significant frequency in domestically produced, leave-on cosmetic products.

CONCLUSION

Preservatives in cosmetics were significantly different according to source of production and type of cosmetics.

Occupational irritant contact dermatitis diagnosed by analysis of contact irritants and allergens in the work environment

BACKGROUND

Irritant contact dermatitis (ICD) is a common diagnosis in patients with occupational contact dermatitis (OCD). Studies are lacking on the usefulness of material safety data sheets (MSDSs) in making the diagnosis of ICD.

OBJECTIVE

To characterize irritant exposures leading to the diagnosis of occupational ICD (OICD), and to evaluate the occurrence of concomitant exposures to contact allergens.

METHODS

We included 316 patients with suspected occupational hand dermatitis, referred to the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte, Denmark during January 2010-August 2011, in a programme consisting of a clinical examination, exposure assessment, and extensive patch/prick testing.

RESULTS

OCD was diagnosed in 228 patients. Of these patients, 118 were diagnosed with OICD. The main irritant exposures identified were wet work (n = 64), gloves (n = 45), mechanical traumas (n = 19), and oils (n = 15). Exposure to specific irritant chemicals was found in 9 patients, and was identified from MSDSs/ingredients labelling in 8 of these patients. Review of MSDSs and ingredients labelling showed that 41 patients were exposed to 41 moderate to potent contact allergens, and 18 patients were exposed to 25 weak workplace contact allergens.

CONCLUSION

In the present study, the systematic exposure assessment did not reveal any new irritants. MSDSs have a limited role in the investigation of ICD.

The combined diagnosis of allergic and irritant contact dermatitis in a retrospective cohort of 1000 consecutive patients with occupational contact dermatitis

BACKGROUND

The diagnosis of combined allergic and irritant contact dermatitis is an accepted subdiagnosis for hand dermatitis, and it is often considered in a patient with contact dermatitis, a positive and relevant patch test result, and wet work exposure. We therefore hypothesize that it is arbitrary for wet work exposure to be taken into consideration in a patient with newly diagnosed relevant contact allergy. Furthermore, an overestimation of the diagnosis will probably occur if the criteria for wet work exposure are applied correctly, as many occupations have an element of wet work.

OBJECTIVES

To find the statistically expected number of combined allergic and irritant contact dermatitis cases in 1000 patients, and to evaluate the diagnostic criteria for the diagnosis.

METHODS

One thousand consecutive patients with occupational contact dermatitis from a hospital unit in Denmark were assessed.

RESULTS

The expected number of cases with the diagnosis of combined allergic and irritant contact dermatitis was 0.33%, as compared with the observed number of 6.4%. Females occupied in wet occupations were often diagnosed with combined allergic and irritant contact dermatitis (p < 0.005).

CONCLUSION

The diagnosis of combined allergic and irritant contact dermatitis should be used critically to avoid misclassification, and possible criteria for the diagnosis are proposed.

Isothiazolinones in commercial products at Danish workplaces

BACKGROUND

In recent years, a steep increase in the frequency of occupational contact allergy to isothiazolinones has been reported from several European countries.

OBJECTIVE

To examine the extent and occurrence of isothiazolinones in different types of product at Danish workplaces.

METHODS

Seven different isothiazolinones were identified in the Dictionary of Contact Allergens: Chemical Structures, Sources, and References from Kanerva's Occupational Dermatitis. By use of the chemical names and Chemical Abstracts Service numbers for these chemicals, information on products registered in the Danish Product Register Database (PROBAS) was obtained.

RESULTS

All seven isothiazolinones were registered in PROBAS. The top three isothiazolinones registered were: benzisothiazolinone (BIT), registered in 985 products, methylisothiazolinone (MI), registered in 884 products, and methylchloroisothiazolinone (MCI)/MI, registered in 611 products. The concentration ranges were 0.01 ppm to 45% for BIT, 0.01 ppm to 10% for MI, and 0.01 ppm to 14.1% for MCI/MI. The most common product type was 'paint and varnish'; five of the seven isothiazolinones were registered in this type of product.

CONCLUSION

Isothiazolinones are present in multiple products registered for use at workplaces, and may occur in high concentrations.