Allergic reactions to henna-based temporary tattoos and their components

The Skin Sensitisation of Cosmetic Ingredients: Review of Actual Regulatory Status

All cosmetics products must be safe under foreseeable conditions of use. Allergenic responses are one of the most frequent adverse reactions noted for cosmetics. Thus, the EU cosmetics legislation requires skin sensitisation assessment for all cosmetics ingredients, including the regulated ones (for which the full toxicological dossier needs to be analysed by the Scientific Committee on Consumer Safety (SCCS)) and those (perceived as less toxic) which are assessed by industrial safety assessors. Regardless of who performs the risk assessment, it should be carried out using scientifically and regulatory body-accepted methods. In the EU, reference methods for chemical toxicity testing are defined in the relevant Annexes (VII-X) of the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation. Recommendations for Skin Sensitization (Skin Sens) testing are provided in Annex VII, and this particular endpoint information is required for all EU-registered chemicals. Historically, in vivo animal and human methods have been used. Both raise ethical doubts, and some of them cause practical problems in the objective analysis of skin sensitising potency. Previous decades of huge effort have resulted in the regulatory acceptance of the alternative Skin Sens IATA (Integrated Approaches to Testing and Assessment) and NGRA (Next Generation Risk Assessment). Regardless of the testing issues, a serious sociological problem are observed within the market: the consumer assumes the presence of strong sensitisers in cosmetics formulations and insufficient risk management tools used by the industry. The present review aims to provide an overview of methods for assessing skin sensitisation. Additionally, it aims to answer the following question: what are the most potent skin sensitisers used in cosmetics? The answer considers the mechanistic background along with the actual regulatory status of ingredients and practical examples of responsible industry solutions in the area of risk management.

Contact Allergy in Children with Atopic Dermatitis: A Retrospective Study

Background:

The relationship between atopic dermatitis and allergic contact dermatitis is frequently debated, particularly in children. The impaired skin barrier of atopic subjects can facilitate the penetration of exogenous agents and its mutations in the filaggrin gene might be implicated in an increased risk to develop contact dermatitis. Moreover, atopic children are protractedly exposed to chemical substances contained in skin care products from an early age.

Patients And Methods:

The aim of this retrospective study is to determine if atopic children are more prone to allergic contact dermatitis and which substances are more frequently related to this disease. From 2014 to 2016, a total of 268 children under 14 years with a history of eczematous dermatitis, of whom 141 (52.6%) were affected, and 127 (47.4%) were not affected by AD, underwent patch testing with the baseline S.I.D.A.P.A standard series.

Results:

Based on the results of our study, the prevalence of contact allergy in atopic children is comparable to that noted in non-atopic children. The most frequent causes of contact allergy in children are fragrances, and their prevalence is significantly higher in atopic children (19.9%) than in non-atopic ones, (11.8%; p < .05).

Conclusion:

Our study highlights the importance of patch testing in atopic children for continuously monitoring the trends and changes of contact allergies that are a common disease and is even significantly increasing for some allergens, as fragrances. We may speculate that the protracted use of skincare products, associated with the impaired skin barrier of atopic children, enhances the risk of sensitization to the ingredients of these products.

IL-24 contributes to skin inflammation in Para-Phenylenediamine-induced contact hypersensitivity

Para-Phenylenediamine (PPD) is an aromatic amine used in hair dyes and in temporary black henna tattoos, which is a frequent cause of allergic contact dermatitis (ACD). ACD is a skin inflammatory reaction characterized by modifications such as spongiosis, exocytosis and acanthosis. The aim of this study is to characterize the expression and the role of IL-20-related cytokines, including IL-19, IL-20, IL-22 and IL-24, in ACD. The expression of IL19, IL20, IL22 and IL24 is increased in affected skin from PPD allergic patients compared with uninvolved skin. In addition, the expression of these cytokines positively correlates with clinical symptoms. To assess their role in ACD, we set up a mouse model of PPD-induced allergic contact dermatitis and we showed that, in contrast to Il22-deficient mice, Il22ra1-, Il20rb- and Il24-deficient mice are partially protected against development of PPD-induced contact hypersensitivity. These mice have decreased ear thickening and less acanthosis compared with WT mice after PPD treatment. In addition, the absence of IL-22R, IL-20R2 or IL-24 affects the recruitment of neutrophils into the skin but not the total IgE production. Taken together, these results demonstrate the implication of IL-24 via the IL-20R type II receptor in the inflammatory process of ACD.

Hypersensitivity reactions due to black henna tattoos and their components: are the clinical pictures related to the immune pathomechanism?

Hypersensitivity to para-phenylenediamine (PPD) and related compounds induced by temporary black henna tattoos has become a serious health problem worldwide. Different patterns of sensitization with various clinical aspects are described in literature due to PPD associated to henna tattoo and these manifestations are likely correlated with the immunological and dermatological pathomechanisms involved. Henna is the Persian name of the plant Lawsonia inermis, Fam. Lythraceae. It is a woody shrub that grow in regions of North Africa, South Asia, India and Sri Lanka. Nowadays it is rather frequent to see temporary "tattoos" performed with henna. To make tattoos darker and long-lasting PPD has been associated to henna in tattoo drawings mixtures, so obtaining "black henna". In these years there has been a rise of contact sensitization to PPD and in medical literature an increased number of cases have been reported on temporary henna tattoo application. Here we review the various clinical patterns related to PPD and henna tattoo, to investigate the possible link between clinic-morphological pictures and the immunological response to PPD and henna. The literature underlines that different clinical manifestations are related to black henna containing PPD, and its derivative products may cause delayed-type as well as immediate-type reactions. Further studies are needed to investigate the relationship between clinical and morphological aspects of PPD contact dermatitis and the T cell subsets predominance.

Lawsonia inermis L. (henna): ethnobotanical, phytochemical and pharmacological aspects

ETHNOPHARMACOLOGICAL RELEVANCE

The use of Lawsonia inermis L. (henna) for medicinal and cosmetic purposes is inextricably linked to ancient and modern cultures of North Africa and Asia. Literature and artwork indicates that Lawsonia inermis played an important holistic role in the daily lives of some ancient cultures, providing psychological and medicinal benefits, as well as being used for personal adornment. Although henna was historically applied to the hands and feet to protect against fungal pathogens and to hair to combat lice and dandruff, other traditional uses include the treatment of liver and digestive disorders, reduction of tissue loss in leprosy, diabetic foot disorders and ulcers.

PHYTOCHEMISTRY

Almost 70 phenolic compounds have been isolated from various parts of the plant. Naphthaquinones, which include the dyeing principle lawsone, have been linked to many of the pharmacological activities. The terpene, β-ionone is largely responsible for the pungent odour of the essential oil isolated from the flowers. In addition to other volatile terpenes, some non-volatile terpenoids, a single sterol, two alkaloids and two dioxin derivatives have also been isolated from the plant.

BIOACTIVITY

Henna is a pharmacologically important plant with significant in vitro and in vivo biological activities. Although a myriad of pharmacological activities have been documented, the antioxidant and antimicrobial activities are the most thoroughly investigated. Some incidents of adverse reactions following application to the skin have been reported, but these are mainly confined to cases involving individuals with glucose-6-phosphate dehydrogenase deficiency and reactions to adulterants added to henna products.

CONCLUSIONS

Adulteration of henna is very common and may have resulted in unwarranted scientific findings. Phytochemical profiling studies of the plant, which are crucial for the establishment of proper quality control protocols, are lacking and hamper the development of medicinal products. Although many in vitro studies have been conducted to evaluate the pharmacological activities and many in vivo studies have focussed on the toxicity of extracts, more in vivo studies to validate pharmacological activities are needed. The roles of specific compounds and their synergies have not been comprehensively investigated.

Modulation of basophils' degranulation and allergy-related enzymes by monomeric and dimeric naphthoquinones

Allergic disorders are characterized by an abnormal immune response towards non-infectious substances, being associated with life quality reduction and potential life-threatening reactions. The increasing prevalence of allergic disorders demands for new and effective anti-allergic treatments. Here we test the anti-allergic potential of monomeric (juglone, menadione, naphthazarin, plumbagin) and dimeric (diospyrin and diosquinone) naphthoquinones. Inhibition of RBL-2H3 rat basophils' degranulation by naphthoquinones was assessed using two complementary stimuli: IgE/antigen and calcium ionophore A23187. Additionally, we tested for the inhibition of leukotrienes production in IgE/antigen-stimulated cells, and studied hyaluronidase and lipoxidase inhibition by naphthoquinones in cell-free assays. Naphthazarin (0.1 µM) decreased degranulation induced by IgE/antigen but not A23187, suggesting a mechanism upstream of the calcium increase, unlike diospyrin (10 µM) that reduced degranulation in A23187-stimulated cells. Naphthoquinones were weak hyaluronidase inhibitors, but all inhibited soybean lipoxidase with the most lipophilic diospyrin, diosquinone and menadione being the most potent, thus suggesting a mechanism of competition with natural lipophilic substrates. Menadione was the only naphthoquinone reducing leukotriene C₄ production, with a maximal effect at 5 µM. This work expands the current knowledge on the biological properties of naphthoquinones, highlighting naphthazarin, diospyrin and menadione as potential lead compounds for structural modification in the process of improving and developing novel anti-allergic drugs.

Side-effects of henna and semi-permanent 'black henna' tattoos: a full review

Henna, the dried and powdered leaf of Lawsonia inermis, is widely used as a dye for the skin, hair, and nails, and as an expression of body art, especially in Islamic and Hindu cultures. As it stains the skin reddish-brown, it is also called red henna. Black henna is the combination of red henna with p-phenylenediamine (PPD), and is used for temporary 'black henna tattoos'. This article provides a full review of the side-effects of topical application of red and black henna, both cutaneous (allergic and non-allergic) and systemic. Red henna appears to be generally safe, with rare instances of contact allergy and type I hypersensitivity reactions. In children with glucose-6-phosphate dehydrogenase deficiency, topical application of henna may cause life-threatening haemolysis. Black henna tattoos will induce contact allergy to its ingredient PPD at an estimated frequency of 2.5%. Once sensitized, the patients may experience allergic contact dermatitis from the use of hair dyes containing PPD. There are often cross-reactions to other hair dyes, dyes used in textiles, local anaesthetics, and rubber chemicals. The sensitization of children to PPD may have important consequences for health and later career prospects. Systemic toxicity of black henna has been reported in certain African countries.