Telling apart psoriasis and eczema

July 9, 2014 § Leave a comment

Photo of a patient's skin who has psoriasis plaques in the center and eczema around the plaques. Photo courtesy of Kilian Eyerich.

Photo of a patient’s skin who has psoriasis plaques in the center and eczema around the plaques. Photo courtesy of Kilian Eyerich.

Eczema and psoriasis are chronic inflammatory skin diseases that sometimes are hard to tell apart because the irritated skin can look similar in both. Each condition requires a different kind of medical treatment. But when doctors can’t tell apart one condition from the other, it’s difficult for them to prescribe treatments, which can be expensive to undertake. Now, in a paper just out in the journal Science Translational Medicine, researchers have identified how the two conditions differ at the molecular level, which could guide clinicians in the future in telling the two skin diseases apart and prescribing treatment regimens.

Kilian and Stefanie Eyerich at the Technical University in Munich, Germany, know the frustrations of distinguishing between eczema and psoriasis firsthand.  “In our daily clinical practice, it is a common problem,” says Kilian Eyerich. “This is especially true for lesions on the hands, feet or scalp.”

The two investigators, who led the current study, noticed that some patients suffer from both psoriasis and eczema, with the manifestations of the two conditions sometimes appearing “just inches away from each other,” he says. He adds that this kind of patient is the “perfect model for us to investigate the pathogenesis of psoriasis and eczema” without the confounding factors of gender, age, genetics and environmental exposure.

The investigators recruited 24 patients who had both psoriasis and eczema and carried out polymerase chain reaction-based whole-genome expression analyses on unaffected skin, psoriasis lesions and eczema patches.

They found that psoriasis was mostly similar, on the molecular level, to a wound-healing reaction. The condition is known to be an immune response operating in overdrive in the outermost layer of the skin, causing scaly plaques. In contrast, eczema involved a different set of immune cells. These cells interfered with the epidermal barrier and the skin’s immune response. As a result, skin areas with eczema were susceptible to bacterial, fungal and viral infections, which inflame the skin even more.

Based on their results, the investigators zoomed in on two gene products, nitric oxide synthase 2 and the chemokine CCL27, which appeared to be specifically regulated in psoriasis. Eyerich says the expression levels of these two genes can help clinicians tell apart psoriasis and eczema. Indeed, in a different group of 53 patients, the investigators used these two genes to confirm diagnoses for some, provide new diagnoses and correct misdiagnoses.

Eyerich cautions that they need to reproduce their findings in larger groups of patients and use other molecular techniques, such as immunohistochemistry, to confirm their findings. But he hopes that the work will make an impact. “We hope this work will pave the way toward personalized medicine in inflammatory skin diseases,” he says. “We want to expand our investigation of the molecular signature of the diseases … to enable us to predict the perfect therapy for each individual patient based on his or her molecular signature in the future.”


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