Atopic Dermatitis (AD) is an inflammatory skin condition which is more common in Urban Environments and in Asians
-It is associated with atopy which includes Eczema, Asthma and Hay Fever
Clinically, the lesions are distributed in different age groups, but the skin in invariably dry (xerosis)
-The main symptom is itch which can be so severe as to interfere with sleep.
This study evaluates the role of Endothelin 1 (Et-1)(which is a part of a group of peptides mainly synthesized in blood vessels).
–ET-1 plays a role in pruritus (non-histamine dependent)
-To read more on endothelins, click HERE
At the same time Il-25 is measured; this is an important cytokine in AD
The main finding is that Il-25 and Et-1 are upregulated in AD (immunohistochemistry in both mice and humans)
-These two mediators stimulate each other (revealed in vitro when studying HaCaT cell lines), so that a vicious circle is created and this could explain how the condition worsens as the itching and scratching become more intense.
Conclusion
Could this itch generating molecular pathway be the target of a treatment to control itch ?
(In more detail Il-25 upregulated ET-1 mRNA and Il-25 was inhibited by ERK 1/2 or JNK inhibitor. Conversely Et-1 induced Il-25 expression and ET-1 was inhibited by ET-B receptor antagonists ERK 1/2 and p38 inhibitor but not ET-B receptor antagonist or JNK inhibitor)
Other findings on ET-1: it plays a role in pigmentation (click HERE to read more) and it is interesting to note that the more lichenified the lesions are, the more pigmented they become – particularly so in darker phototypes.
Source of information: P05-22 (O1-10) Kido-Nakahara M. et al. Mutual upregulation of endothelin-1 and Il-25 in atopic dermatitis.JSID Annual Meeting (Japanese Society of Investigative Dermatology, 日本研究皮膚科学会) 2015 – Okayama, Japan
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