Ichthyosis, sometimes called the ‘red skin disease’, has been frustrating both patients suffering from it and their doctors. The difficulty has been that, without an understanding of what biological mechanism triggers the patches of scaly, dry skin—that can become painful and red—treatment has only been able to focus on easing symptoms. Some recent findings are hoping to change this; they propose a possible cause that can be targeted with medication.
In Brief: Ichthyosis
The ichthyoses are a collection of rare, genetic skin disorders that are characterized by patches of dry, scaly skin that can crack easily and expose raw skin underneath. In the milder form, which affects about 1–300 people, the effects are more localized and can sometimes be mistaken for extreme dryness.
Most cases cover large swaths of the body, particularly on the trunk, abdomen, buttocks, or legs. In addition to being potentially disfiguring, the scales can make the skin more prone to cracking (raising infection risk) or impair the ability to sweat. In the most severe and rare incidences (between 1 and 300,000) the patches can form thick “plates” with large red cracks that can restrict breathing and create significant vulnerability to infection. For an idea of what this can look like, look up “harlequin ichthyosis”, but be aware that the images can be very disturbing.
The study compared 21 biopsies that were taken from patients with different types of ichthyosis to samples obtained from healthy controls, as well as to patients with atopic dermatitis and psoriasis. Normally, such a small sample is a bad thing in a study. In this case, however, the rarity of ichthyosis means it was a necessary evil.
Various gene expressions and other markers were compared between the samples to look for any commonalities or outliers. The strongest correlation was found between ichthyosis and the Th17 gene pathway, which is an arm of the immune system. These genes were found to be much more active in ichthyosis patients than normal. More importantly, the height of the pathway’s activity seemed connected to the severity of the skin disorder’s symptoms.
What This Means
Dr. Paller, who was behind the research, currently plans to begin testing potential drugs that can target the Th17 pathway and calm it down. Assuming the pathway is a causative factor in ichthyosis, this could offer relief to patients. Dr. Paller’s plans revolve around a psoriasis drug called secukinumab. Since psoriasis also involves over-activity in the Th17 pathway, it is hoped that there will be an overlap in treatment effectiveness as well.
Paul, M., “Research Finally Reveals Reason For Perplexing Red Skin Disease,” Northwestern web site, September 19, 2016; http://www.northwestern.edu/newscenter/stories/2016/09/research-reveals-reason-skin-disease.html, last accessed September 21, 2016.
Paller, A., et. al., “An IL-17-dominant immune profile is shared across the major orphan forms of ichthyosis,” Journal of Allergy and Clinical Immunology, 2016; http://dx.doi.org/10.1016/j.jaci.2016.07.019.