A team of scientists from the University of Leuven in Belgium has discovered an essential process that helps your brain understand that you’ve scratched enough. An achievement that could revolutionize the treatment of millions of patients suffering from chronic skin conditions such as eczema and psoriasis.
The culprit is a protein called TRPV4, an ion channel that serves as a gatekeeper for sensory nerve fibers. Scratching the itch causes TRPV4 to send negative feedback to the spinal cord and brain, letting them know that enough has been done.
Without this signal, scratching continues unchecked, which could explain why people with chronic itch become trapped in relentless scratching cycles.
“When we scratch an itch, at some point we stop because there is a negative feedback signal that tells us we are satisfied,” explains Roberta Gualdani, who led the study. “Without TRPV4, the mice don’t feel this feedback, so they keep scratching much longer than normal.”
Gualdani’s team developed genetically modified mice that disabled TRPV4 only by deleting sensory neurons. The researchers used genetic testing along with behavioral assessments to study mice that developed chronic itching symptoms consistent with atopic dermatitis.
The mice lacking TRPV4 did not scratch themselves often, but the duration of each fight was very long compared to normal conditions. This was not contradictory; rather, it showed one basic fact: that TRPV4 doesn’t just cause itching; it is responsible for initiating the process that tells your body to stop.
TRPV4 has two functions: when it acts on skin cells, it causes itching, and when it acts on neurons, it determines and regulates how much scratching occurs. “Broadly blocking TRPV4 may not be the solution,” Gualdani says. “Future therapies may need to be much more targeted, perhaps working only in the skin without disrupting the neuronal mechanisms that tell us when to stop scratching.”
Chronic itch affects millions of people worldwide, but treatment options remain severely limited.
