Causes of Itchy Skin Gain Understanding with Possible Remedies at One-of-a-Kind Center for Research

    By Kathleen Berger, Executive Producer for Science & Technology

    Itching and scratching consumed Karen Berger’s life. The itching was debilitating for two years as it diminished Karen’s quality of life. The itching started with rashes on her back and spread to most areas of her body. She described the itching as unbearable, unrelenting, uncontrollable and untreatable. It never went away.

    “You would scratch until you bleed. I would wake up in the morning and there would be blood on the sheets because I would scratch during the night and wasn’t even aware of it,” Karen said.

    At the time, no one could diagnose the itch. Karen went to specialists, including dermatologists and allergists. She tried every test and cream they offered, but nothing worked. In fact, her condition got worse. Eventually, Karen was sent to see a dermatologist who specializes in chronic itch. Dr. Brian Kim, MD, is assistant professor of dermatology and co-director of the Center for the Study of Itch & Sensory Disorders at Washington University School of Medicine in St. Louis.

    Dr. Kim said Karen has a type of itch with an unknown cause, a condition called idiopathic pruritus. For Karen, Dr. Kim prescribed the anti-inflammatory drug Xeljanz, a rheumatoid arthritis medication. It’s a potential new therapy for chronic itch after Kim and his research team had a breakthrough discovering an itch molecule. The team showed how sensory neurons are activated by an immune signaling molecule called interleukin-4 (IL-4).

    “We found a link between the immune system and the nervous system that wasn’t previously appreciated, showing that this immune molecule directly stimulates nerve cells to cause itching,” Kim said.

    The researchers determined that IL-4 stimulates a key protein within nerve cells, called JAK1. This protein is a critical component of chronic itching. That finding led the team to suspect that JAK1 may be a uniquely sensitive target for multiple types of itch, even itching of an unknown cause. The tofacitinib arthritis drug, with the brand name Xeljanz, blocks this protein.

    This led to a small study providing proof that the Xeljanz medication works for chronic itch patients. On average, patients in the study experienced 80% improvement.

    “Once I started taking it, within 24 hours the intensity of the itch started to subside,” said Karen. “Within two to three days, it was like watching it go away. And within a week, I was fairly clear. But within two weeks, I was completely clear. I was back to my normal skin then.”

    According to Kim, there is no other research center fully dedicated to itch in the U.S. He said about 15% of people suffer from chronic itch, most often caused by inflammatory conditions like eczema and psoriasis, or associated with cancers and nerve disorders. Itching may accompany rashes or not. Kim said idiopathic pruritus, or itching from an unknown cause, is more of a problem as people age.

    “Your nervous system starts to wear out,” he explained. “The other thing we also recognize is that your skin gets weaker and drier, more wrinkly and thinner. So you’re now much more susceptible to environmental insults to your skin and to the nerves that go to your skin. We also know that your immune system changes. It’s really a combination of those things that lead to some level of inflammation, your nerves going haywire, your skin barrier not being able to recover from insults that we think results in this kind of itch and why it’s so prevalent.”

    Researchers at the Center for the Study of Itch & Sensory Disorders regularly have studies underway, concluding or about to get started.

    Kim is leading a clinical trial for itch patients with new technology that goes into an itch patient’s home. The Emerald device is a touchless sensor and machine learning platform for health analytics. In the trial, Emerald detects patient movements, including scratching, with correlating data. The hope is for machine learning to aid diagnosis and intervention.

    And what about that pesky back itch that’s hard to reach? It’s likely the reason why a back scratcher was invented! Notalgia Paresthetica (NP) is a chronic itch disorder that results in localized itching on the back. Kim says there is a promising new drug that acts on sensory neurons to suppress the itch. He’s beginning a phase two clinical trial with NP patients to investigate.

    Itch from atopic dermatitis, or eczema, is another area of study with success. Kim’s team recently identified an entirely new mechanism involved in a form of itch in eczema. The mechanism is a particular antibody that is also a central player in environmental and food allergies. Kim said the findings unveil why allergic processes are poorly understood.

    Through research, Kim is hoping to improve the quality of life for itch patients like Karen. After two years of suffering, her life changed within a matter of days. Karen said she feels fortunate that she has her quality of life back to where it was before that first rash.