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Atopic dermatitis: what not to wear

Rupert Mason
MBBS MRCS LRCP
GP
Clinical Assistant
Dermatology
Bedford Hospital

In a society seemingly obsessed with Trinny and Susannah, and the antisocial exploits of supermodels, you could be excused for thinking that the sole purpose of clothes is to make a personal fashion statement.
But for many people there is a lot more to clothes than what they look like. For the child suffering from atopic dermatitis, the fabric that is next to his or her skin can have a much more profound significance.

Atopic dermatitis
Atopic dermatitis is a chronic relapsing inflammatory skin disease that usually starts during the first years or months of life. One crucial aspect of the disease is that it impairs the barrier function of the epidermis. This can result in increased transepidermal water loss and the penetration of environmental allergens into the skin, which set off immunological reactions and inflammation.
In addition, the stratum corneum is highly susceptible to colonisation by various bacteria, mainly Staphylococcus aureus. It is believed that this overgrowth with Staph aureus exacerbates or contributes to skin inflammation by secreting superantigens which further activate inflammatory cells. The degree of colonisation has been shown to be associated with disease severity and for this reason topical and oral antibiotics are often used to keep atopic dermatitis under control, along with emollients, steroids and immunomodulators.
Staph aureus is by no means the only aggravating factor in atopic dermatitis. Others include climatic factors, inhaled allergens, stress and chemical and physical irritants. Control of these factors is important for effective management of the disease. One potential irritant that is often forgotten by healthcare professionals is clothing. All of us spend a lot of time with some type of fabric next to our skin. For patients with atopic dermatitis it is particularly important to choose a garment that at least does not aggravate the condition, and at best helps to control it.
The basic choice is between synthetic or natural fabrics. Synthetic fabrics are produced by the chemical processing of petroleum. These polyurethane materials have a number of practical advantages, such as stable colouring and durability, but they are not the fabric of choice for atopic skin. Nylon can cause allergic contact dermatitis and contact urticaria. One randomised study on 55 patients with atopic dermatitis and 31 healthy controls compared the irritative capacity of three different synthetic materials to cotton.(1) The results showed that the synthetic materials caused significantly greater itch and discomfort than cotton in patients with atopic dermatitis.
Natural fabrics are derived from plant fibres, eg, cotton and linen, or animal fibres, eg, wool and silk. The choice between these can be guided by examining their individual properties.

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Wool 
Interestingly, the main constituent of wool is keratin, the same protein that is the main constituent of human skin, but that link does not result in compatibility. Wool fibre has frequently been shown to be an irritant to the skin of atopic patients, and the intensity of itching from wool fibres has been shown to increase in relation to the physical characteristics of the type of fibre.

Cotton 
Cotton is currently the most commonly used textile for patients with atopic dermatitis. It is relatively soft and naturally abundant. However, it is prone to bacterial and fungal attack, and has a crucial flaw in its structure. It is made up of many short (1-3 cm) fibres with flat irregular sections. These fibres extend and contract as they absorb moisture producing an abrasive rubbing movement that may irritate the skin. As with all fabrics, the potential for irritation can be aggravated by the use of reactive dyes to try and make the garments look more attractive. Despite these theoretical drawbacks, cotton is commonly recommended as the fabric of choice for patients with atopic dermatitis.

Silk
Natural silk is a single thread secreted by an industrious little fellow known as Bombyx mori, aka the silkworm. It is made up of a double filament of protein material called fibroin which is glued together with a sticky substance called sericin. This natural silk is woven into the shiny fabric that we are all familiar with. However, during the process of production of silk for medical use the sericin is removed because it is a potential skin irritant. The treated fibroin-based silk has virtually no allergenic potential; only one case of hypersensitivity to silk fibroin has ever been reported in world literature, and silk has been safely used as a suture material for many years. In contrast to the short stubby fibres of cotton, each silk thread is made up of many filaments up to 800 m long and this produces a fabric that is perfectly smooth and does not cause friction on the skin. It also has greater ability to absorb moisture than cotton, and helps to maintain the body temperature by reducing excessive sweating and moisture loss. These properties make this specially treated silk a natural candidate for an atopic-friendly fabric.

New developments
An intriguing recent development is the concept of materials impregnated with an antimicrobial agent. Silver has antimicrobial properties and some studies have investigated the potential benefits of silver-impregnated fabrics with eczema. The case for them is still unproven, and there are concerns about bacterial resistance and long-term local and environmental effects, to the extent that Sweden's state-run pharmacy, Apoteket has recently banned the sale of silver-impregnated dressings.
Perhaps more encouraging is the development of silk-impregnated with an "antimicrobial shield". This technique involves permanently bonding a physical antibacterial to the fabric and has the advantage of being well established following many years use with operating theatre linen. The proven benefit of the technology is to protect the fabric from microbial contamination without leaching onto the skin.
But the development of clothing made out of antimicrobial-impregnated silk poses a number of interesting questions in view of the role of Staph aureus as a superantigen in atopic dermatitis. Does the antimicrobial shield reduce the colonisation of atopic skin by Staph aureus? If so, does this result in any clinical benefit? At the moment the answer is we don't know. There is no in-vivo evidence to show that antimicrobial-impregnated silk significantly reduces the overgrowth of Staph aureus. However there is evidence to show that wearing it does help to improve the clinical state of the skin.

Silk versus cotton
In a study published in the British Journal of Dermatology, Ricci et al investigated the clinical effectiveness of this silk in the treatment of atopic dermatitis.(2) Forty six children with active disease were randomised to silk or cotton garments to be worn next to the skin for one week. The only other agents prescribed were topical moisturisers. The overall severity of the disease was monitored using a validated scoring index (SCORAD). In addition, the local score of an area covered by silk clothing was compared with the local score of an uncovered area in the same child. At the end of the study there was a significant decrease in the severity of atopic dermatitis in the silk group, but no significant change in the cotton group. Also the improvement in the mean local score of the silk-covered areas was significantly greater than that of the uncovered areas. The authors concluded that the use of silk clothes may be useful in the management of atopic dermatitis in children, a conclusion that has been supported by a number of other studies.(3-5)
When it comes to deciding what to wear with atopic dermatitis the decision should be determined by the evidence-base. The data on clothing and atopic dermatitis are not extensive by modern standards, and there is always a need for more. The existing studies are relatively small and unavoidably hampered by practical restrictions in methodology - you cannot mask the physical difference between silk and cotton for a double-blind comparison. Nevertheless, there is now a growing body of good evidence to support the recommendation of silk as the fabric of choice for atopic dermatitis.

References

  1. Diepgen T, Stabler A, Hornstein O. Textile intolerance in atopic eczema - a controlled clinical study. Z Hautkr 1990;65:907-10.
  2. Ricci G, Patrizi A, Bendandi B, et al. Clinical effectiveness of a silk fabric in the treatment of atopic dermatitis. Br J Dermatol 2004;150:127-31.
  3. Senti G, Steinmann L, Fischer B, et al.  Antimicrobial silk clothing in the treatment of atopic dermatitis proves comparable to topical corticosteroid treatment. Dermatology 2006;213;228-33.
  4. Ricci G, Patrizi A, Mandrioli F, et al. Evaluation of the antibacterial activity of a special silk textile in the treatment of atopic dermatitis. Dermatology 2006;213;224-7.
  5. Arcangeli F, Feliciangeli M, Pierleoni M, et al. Silk tubular clothes in paediatric atopic dermatitis. Poster presentation 7th Congress ESPD. Madrid; November 2002.