Consider other triggers beyond food in treating atopic dermatitis

LOUISVILLE, Ky. — Patients may worry about how food allergens impact atopic dermatitis, but there often is more to the story, according to a presentation at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

According to Kelly Maples, MD, chair of the ACAAI Dermatology Committee, patients who want to understand the disease process often ask her and her colleagues about the relationship between food allergy and AD.

For instance, Maples, who also is an associate professor of pediatrics and internal medicine at Eastern Virginia Medical School, Children’s Hospital of the King’s Daughters, and a member of Healio’s Allergy/Asthma Peer Perspective Board, said she is asked, “What foods should I avoid to make my eczema better?” and “My baby has eczema. Does this mean she has food allergies?”

Patients ask these questions because they are bombarded by the message that food allergies cause AD, Maples continued, although there are many other triggers to consider.

Kelly Maples

Intrinsic triggers may include allergic sensitization, skin barrier dysfunction, impaired innate immunity, genetics, Th2 or allergic cytokines such as IL-4 and IL-13, thymic stromal lymphopoietin, proteases, substance P and nerve growth factor, Maples said.

Extrinsic triggers may include items such as cosmetics, clothing, soaps and detergents; environmental factors such as heat, humidity and aeroallergens; and personal aspects such as emotional stressors and the microbiome, among other causes.

“While patients can’t avoid all of these triggers, there’s a lot that we can do to help them adapt to their condition to achieve clearer, less itchy skin,” Maples said.

Specific triggers, solutions

For example, soap leads to the increased breakdown of corneodesmosomes and corneocyte desquamation, Maples said, as its alkaline pH increases the skin’s pH from 5.5 to the optimal value for protease activity, which is 7.5 or greater.

“Baths and showers help replace epidermal water loss, but patients with eczema should be avoiding soap and skincare products with an alkaline pH, as well as detergents and fragrance,” Maples said.

Sodium lauryl sulfate, a common detergent found in skin cleansers, breaks down the lipid lamella component of the skin barrier. Cocamidopropyl betaine, lanolin and fragrance can have negative effects as well, Maples continued, as these may cause allergic contact dermatitis in some eczema patients.

“The reason baths get such a bad rap is because a lot of the things we put in the tub are triggers for atopic dermatitis that we can inform our patients about and help them to avoid,” Maples said.

After bathing, Maples said, patients should use thick cream ointments or moisturizers that include ceramides to reduce transepidermal water loss and rebuild the skin barrier.

Maples also advised patients to avoid rubbing their skin with a washcloth, wearing wool clothing and other synthetic fabrics and leaving long hair down over their neck. Parents should gently wash saliva and food off infants’ faces too, she said.

Outside the bathroom, Maples said, house dust mites, cats and pollen are the most common allergen triggers of AD. Specifically, house dust mites create proteases that break down the skin barrier.

Aeroallergen management can include ventilation, dust mite covers, improved laundry and hygiene procedures, restrictions on pets, protective glasses and masks, and air conditioning that uses pollen filters.

“Always consider adding environmental control measures [for] people with atopic dermatitis,” Maples said. “Telling them to avoid certain environmental allergens can be very helpful. But, we can also consider doing allergen immunotherapy.”

In the microbiome, Staphylococcus aureus produces enterotoxins that break down the skin barrier and enhance type 2 inflammation. These enterotoxins also downregulate cutaneous production of interferon-gamma and tumor necrosis factor. Together with Staphylococcus alpha toxin, enterotoxins may contribute to keratinocyte apoptosis and barrier defects in AD as well.

“Up to 90% of patients with eczema are colonized with Staph aureus, and that’s not seen in healthy controls, nor is it seen in patients with psoriasis,” Maples said.

Staphylococcus has a predilection for type 2 inflammation and produces virulence factors enabling it to evade the host immune system, Maples said, which already may be impaired in patients with AD.

“In addition to breaking down the skin barrier and causing mast cell degranulation, patients colonized with Staph can actually develop type 1 hypersensitivity and have positive IgE and skin prick testing to Staph aureus, so the Staph itself may lead to increased allergic inflammation and worsening AD,” Maples said.

In addition to topical and oral antifungals in select patients, Maples recommended bleach baths for AD patients, although she acknowledged that patients may be intimidated by the terminology.

“We’ve changed our handout to ‘swimming pool baths,’” she said. “It’s the same instructions, and we’ve noticed at our uptake that patients are less hesitant to do it.”

Contact allergens, other triggers

Contact allergens including personal care products and medications designed to control AD may be making patients’ skin worse too, Maples said, noting the distinction between atopic dermatitis and allergic contact dermatitis, which can look a lot alike.

“Allergic contact dermatitis is a delayed or type 4 hypersensitivity reaction that occurs at points of contact when a sensitized individual has been exposed, and the distribution will depend on the exact allergen,” Maples said.

Patients with AD already have a defective epidermal barrier, she said, enabling contact allergens to penetrate the immune system, which leads to sensitization. The bacterial colonization that accompanies AD increases inflammatory cells and enhances sensitization as well, she continued, further setting up allergic contact dermatitis.

Found in 9% of cosmetic products, Maples said, lanolin causes allergic contact dermatitis, particularly in young children. Cocamidopropyl betaine, tocopherol and its esters, phenoxyethanol, fragrances and propylene glycol also are common contact allergens in skin care products for children.

“Consider contact dermatitis in addition to atopic dermatitis. Patients with atopic dermatitis have a high rate of patch test positivity,” said Maples, who also recommends considering patch testing for patients with AD if they're not getting better with treatment.

Even when the trigger is something that patients cannot avoid such as sweat, identification and remediation are possible, Maples said.

“Patients with eczema actually sweat less, and their sweat is different,” Maples said. “It’s less moisturizing. They make less antimicrobial peptides and less secretory IgA, and that’s one reason why they get colonized by Staph aureus easier.”

These patients do not need to avoid sweating, Maples said. But they should be advised to rinse their sweat off when they are done exercising.

Maples also noted the vicious cycle involving itching, scratching and the worsening of AD that follows from the increased release of keratinocyte-derived cytokines. More itching may follow, she continued, in addition to stress, which also can increase production of IL-4 and substance P for more itching and scratching.

“Good skin care with topical steroids is important,” Maples said, although she cautioned that she did not have a perfect solution for the stressful parts of the equation. “Lots of rest and good exercise can help control their atopic dermatitis as well.”

Further, Maples advised clinicians to mind photo-aggravated AD, which may affect up to 16% of AD patients and could be worse in spring and summer. It may be diagnosed with photo-provocation testing with photo-patch testing used to identify photo-contact allergens.

Alterations in circadian rhythms also could impact immune function, with prolonged light exposure and nighttime screen time impacting AD pathophysiology, she continued. Plus, air pollution from wildfires has been associated with increased health care utilization and itch for AD.

“More humid and high sun exposure climates that are getting warmer are also showing increased flares of atopic dermatitis during the warmer time of the year,” Maples added.

Final thoughts

“Always think of skin barrier care and address it when you’re making your skin care recommendations,” Maples said.

Patients with AD should avoid soaps, detergents, fragrances, lanolin, wool and synthetic fabrics, Maples advised, while considering bleach baths and environmental controls. Patients should be sure to rinse off sweat, get enough sleep and limit their evening screen time as well, she continued.

“Do everything you can to prevent scratching,” she said.

For more information:

Kelly Maples, MD, can be reached at kelly.maples1@gmail.com.