Induction of a Hardening Phenomenon by Repeated Application of SLS: Analysis of Lipid Changes in the Stratum Corneum

Irritant Contact Dermatitis — a Review

Purpose of Review

Recent Findings

Summary

Making change easy: A peer-to-peer guide on transitioning to new hand hygiene products

This report summarizes our experiences planning and implementing the transition to a new commercial line of hand hygiene products and their dispensing systems in a large academic health care facility in Toronto, Canada. Our lessons learned are organized into a practical guide made available in 2 different formats: this article and an illustrated peer-to-peer guide (http://www.baycrest.org/wp-content/uploads/HCE-PROG-HH_HighQuality.pdf).

Induction of a hardening phenomenon and quantitative changes of ceramides in stratum corneum

Background

Hardening phenomenon of human skin after repeated exposure to the irritants is well-known, but the precise mechanism remains elusive.

Objective

To modify the previous experimental model of hardening phenomenon by repeated applications of two different concentrations of sodium lauryl sulfate (SLS) solutions to Korean healthy volunteers and to investigate the quantitative changes of ceramides in stratum corneum before and after chronic repeated irritation.

Methods

Eight hundred microliters of distilled water containing 0.1% and 2% SLS was applied for 10 minutes on the forearm of 41 healthy volunteers for 3 weeks. After an intervening 3-week rest, 24-hour patch tests with 1% SLS were conducted on previously irritated sites. Transepidermal water loss (TEWL), erythema index and quantity of ceramide were measured in the stratum corneum before and after irritation.

Results

TEWL values on the sites preirritated with 2% SLS were lower than those with 0.1% SLS. Hardening phenomenon occurred in 24 volunteers at day 44. The changes in ceramide levels were not significantly higher in the hardened skin than in the non-hardened skin.

Conclusion

Repetitive stimulation with a higher concentration of SLS can more easily trigger skin hardening.

Abnormal epidermal barrier in the pathogenesis of contact dermatitis

A crucial role of the epidermal permeability barrier is obvious in contact dermatitis. An intact skin barrier prevents the penetration of harmful substances into the skin. Irritants and allergens that stay on the skin surface and come into contact with the stratum corneum only do not harm the skin. After disruption of the skin barrier, however, irritants may penetrate into the living epidermal layers, injure the keratinocyte membrane, and release cytokines, which leads to inflammation and to irritant contact dermatitis. The skin barrier is often disrupted by chronic exposure to water plus detergents, solvents, or other irritants. A disrupted barrier in irritant contact dermatitis also allows for the penetration of allergens. Allergens may come into contact with Langerhans and T cells, induce immunological reactions, and cause inflammation, which results in allergic contact dermatitis. Treatments in contact dermatitis should restore the skin barrier to prevent relapse of the disease. Topical corticosteroids, most often used in treating contact dermatitis, reduce immunological reactions and inflammation but do not lead to a complete barrier repair. Skin barrier repair is more complete after treatment with calcineurin inhibitors and bland lipid-based emollient; therefore, these preparations should be preferred for long-term treatment of contact dermatitis.

Influence of tumour necrosis factor-α polymorphism-308 and atopy on irritant contact dermatitis in healthcare workers

BACKGROUND

Chronic irritant hand dermatitis is an issue for healthcare workers and may negatively impact infection control.

OBJECTIVES

We examined the effects of a G to A transition at position -308 on the tumour necrosis factor-α (TNF-α) gene on chronically damaged skin of healthcare workers during exposure and recovery from repetitive hand hygiene, after intensive treatment, and on the irritant response in normal skin.

PATIENTS/MATERIALS/METHODS

In 68 healthcare workers with irritant hand dermatitis, we genotyped TNF-α-308 and measured the epidermal response via quantitative digital imaging, erythema, dryness, and barrier integrity.

RESULTS

Excess hand erythema decreased with hand hygiene exposure and increased during time off for AA/GA genotypes, but had opposite effects for GG. AA/GA had smaller reductions in dryness with lotion treatment and larger reductions in excess erythema than GG. The atopic diathesis and heightened neurosensory irritation resulting from water and lactic acid significantly influenced the responses. Repeated exposure to water and sodium lauryl sulfate (0.05, 0.1%) produced higher erythema in normal skin for AA/GA than for GG.

CONCLUSIONS

This study provides evidence that the TNF-α polymorphism at -308 and an atopic history impact the severity of irritation and recovery from exposure and response to treatment for common hand skin products in both chronic irritant hand dermatitis and normal skin.

Individual susceptibility to occupational contact dermatitis

Occupational Contact Dermatitis (OCD) is one of the most common work-related diseases. High risk occupations are in health care, hairdressing, food sector and metal industry. OCD tends to become chronic; persistent OCD often results in impaired quality of life and loss of work ability. The purpose of this article is to review the present knowledge on the factors which determine individual susceptibility to acquire OCD. Recent discoveries regarding genes involved in the skin barrier, inflammatory response and biotransformation of xenobiotics provide more insight in the individual susceptibility for OCD. Knowledge of the factors which predispose to OCD is useful in occupational health practice for the application of preventive measures and for career guidance for apprentices and workers in high risk occupations.

Skin irritation and sensitization: mechanisms and new approaches for risk assessment. 1. Skin irritation

Cutaneous irritation presents a major health problem with serious social and occupational impact. The interaction between an irritant and the human skin depends on multiple factors: the intrinsic properties and the nature of the irritant itself, and specific individual- and environment-related variables. The main pathological mechanisms of irritancy include skin barrier disruption, induction of a cytokine cascade and involvement of the oxidative stress network; all of them resulting in a visible or subclinical inflammatory reaction. In vivo, different non-invasive parameters for the evaluation of skin irritation and irritant potential of compounds and their specific formulations have been introduced, such as epidermal barrier function, skin hydration, surface pH, lipid composition, skin colour and skin blood flow. The diverse physiological changes caused by irritating agents require implementation of a multiparametric approach in the evaluation of cutaneous irritancy.

Differential cytokine expression in skin after single and repeated irritation by sodium lauryl sulphate

In vivo levels of cytokines and presence of neutrophils and eosinophils in skin irritation are not well known. Our objective was to get more insight in inflammatory mediators and markers involved in single and repeated skin irritation. We sampled epidermis-derived fluid using a novel technology that includes application of a negative pressure on the skin after creation of micropores in the stratum corneum by a laser. In nine volunteers, transdermal fluid was sampled after a single 4-h 10% sodium lauryl sulphate exposure and a repeated 3-week exposure (0.1% sodium lauryl sulphate). Twenty-seven cytokines were assessed by multiplex assay, and IL-1alpha, eosinophil cationic protein and myeloperoxidase by enzyme-linked immunosorbent assay. Levels of eosinophil cationic protein were increased after irritation and correlated with levels of myeloperoxidase. The levels of inflammatory mediators showed large interindividual differences in unexposed and exposed skin. Despite this variation, several mediators clearly showed increased levels: CC chemokine ligand (CCL)11, CXCL10 and vascular endothelial growth factor after both single and repeated exposure, IL-1alpha and basic fibroblast growth factor after single exposure and interleukin-1 receptor antagonist (IL-1RA) after repeated exposure. After repeated exposure, CCL5 and the ratio IL-1RA/IL-1alpha both increased compared with single exposure. We conclude that single and repeated irritation induces differential and concerted expression of various inflammatory mediators and markers.

The role of topical calcineurin inhibitors for skin diseases other than atopic dermatitis

The topical calcineurin inhibitors (TCIs) pimecrolimus and tacrolimus are approved for atopic dermatitis but have additional potential in other inflammatory skin diseases. This article reviews their clinical use in non-atopic dermatitis diseases. In seborrheic dermatitis, asteatotic eczema, and contact dermatitis, TCIs are of great benefit and can compete with topical corticosteroids. In psoriasis, TCIs have shown clinical efficacy and safety in facial and intertriginous lesions. Further investigations into possible combinations of TCIs with other established treatments such as UVB irradiation in this disorder are necessary. Initial studies in cutaneous lupus erythematosus have been promising, whereas the response in rosacea and rosacea-like eruptions has been mixed. TCIs have been associated with good clinical responses in oral lichen planus and anogenital lichen sclerosus et atrophicus. In vitiligo, TCIs are associated with some degree of repigmentation, with better results being seen in children and in facial and neck areas. TCIs have a synergistic effect with UVB irradiation in vitiligo. There is a long list of small series and case reports documenting use of TCIs in various other skin conditions that warrant further validation. Although the established mode of action of TCIs is T-cell control, other effects also need to be considered. Specifically, TCIs reduce pruritus and erythema, which cannot be explained by T-cell interactions, and further investigations are needed in these fields.

Metallothionein I and II gene knock-out mice exhibit reduced tolerance to 24-h sodium lauryl sulphate patch testing

BACKGROUND

Metallothioneins (MTs) are a group of proteins widely distributed in tissues regulating metal metabolism, scavenging free radicals, and taking part in immunological reactions. Knockout mice for MT genes I and II (MT(-/-)) exhibit reduced tolerance to ultraviolet B injury in vivo. Upregulation of MT proteins can be found at positive allergy patch-test sites; however, the role of MTs in skin irritation has not been investigated.

AIM

To evaluate the role of MT genes in sodium lauryl sulphate (SLS)-induced skin irritation. SLS is a well-known model irritant in the study of experimental irritant contact dermatitis.

METHODS

Skin irritation was induced in mice by applying closed-patch testing of 2.5%, 5%, 7.5% and 10% SLS in distilled water on the right dorsal skin of MT(-/-) mice for 24 h. Skin irritation was evaluated visually and by the number of infiltrated inflammatory cells in SLS-irritated skin. Homozygous wild-type mice with intact MT genes (MT(+/+)) tested at the same time served as controls.

RESULTS

MT(-/-) mice showed a much higher degree of skin inflammation than did MT(+/+) mice. Numbers of infiltrated inflammatory cells were 312.8 +/- 50.9 vs. 136.2 +/- 13.1 for 2.5%, 430.2 +/- 49.3 vs. 242.6 +/- 28.6 for 5%, 540.2 +/- 28.4 vs. 437.6 +/- 22.2 for 7.5%, and 690.6 +/- 31.0 vs. 559.0 +/- 37.8 for 10% SLS in MT(-/-) and MT(+/+) mice, respectively (P < 0.05, Mann-Whitney U test).

CONCLUSIONS

These results clearly suggest that the MTI and MTII genes may play an important protective role in SLS irritation. It would be valuable to study whether topical MTs can prevent or treat skin irritation.

Stratum corneum cytokines and skin irritation response to sodium lauryl sulfate

Little is known about cytokines involved in chronic irritant contact dermatitis. Individual cytokine profiles might explain at least part of the differences in the individual response to irritation. Our objective was to investigate the relation between baseline stratum corneum (SC) cytokine levels and the skin response to a single and a repeated irritation test. This study also aimed to determine changes in SC cytokine levels after repeated irritation. Transepidermal water loss (TEWL) and erythema were measured in 20 volunteers after single 24-hr exposure to 1% sodium lauryl sulfate (SLS), and during and after repeated exposure to 0.1% SLS over a 3-week period. SC cytokine levels were measured from an unexposed skin site and from the repeatedly exposed site. Interleukin (IL)-1alpha decreased by 30% after repeated exposure, while IL-1RA increased 10-fold and IL-8 increased fourfold. Baseline IL-1RA and IL-8 values were predictors of TEWL and erythema after single exposure (r = 0.55-0.61). 6 subjects showed barrier recovery during repeated exposure. Baseline IL-1RA and IL-8 levels are likely to be indicators of higher skin irritability after single exposure to SLS. Barrier repair in some of the subjects might explain the lack of agreement between the TEWL response after single and repeated irritation.