An 'integrative' approach to understanding itch: lead author Dr. Brian Kim dermatologist and immunologist at the University School of Medicine explains that this itch-'scratch' cycle engages our entire body's immune system and also interacts with behavior and the environment. Initially and throughout evolution, scratching in response to itching arguably flushed parasites, toxins, and other irritants from our skin. But in a condition such as eczema, a condition that dries out the skin, the irritation is constant. Scratching no longer has a beneficial effect and, on the contrary, only exacerbates the itching.
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Scratching is always a harmful reflex: scratching causes skin irritation that damages the outermost skin cells and releases signaling proteins, such as cytokines, that activate itch sensory neurons in the skin. These neurons in turn produce signals that trigger inflammation and, again, that scratching behavior. Itching can also be linked to pain, with certain sensory pathways associated with itch and pain overlapping in the nervous system.
The cytokine pathway: Many teams consider cytokines as therapeutic targets. The cytokine IL-4, for example, is targeted by certain therapies to block an itch neural pathway in eczema. These cytokines thus seem to be promising targets, underline the authors, but, since there are many forms of itching, many causes and many itch-scratch cycles, further research will be necessary to specify the best targets according to the type of itch. itching.
