Chronic pruritus of unknown origin (CPUO) patients may have lower-than-normal levels of metabolite biomarkers in the blood plasma that could point to a cause of their excruciating itch, according to a new study in Scientific Reports.
“Our study found a distinct deficit in certain metabolite biomarkers, including several important amino acids and other metabolites involved in immune system regulation in patients with CPUO compared to a healthy control group,” says study principal investigator Shawn Kwatra, MD, the Joseph W. Burnett Endowed Professor and Chair of Dermatology at UMSOM and Chief of Service Dermatology at the University of Maryland Medical Center (UMMC) in Baltimore, MD, in a news release. “This is an exciting finding because it provides novel insights into the cause of this condition and identifies potential future therapeutic targets to consider.”
In the study, Dr. Kwatra and his colleagues compared blood plasma samples from patients with CPUO and matched healthy control patients. They found lower levels of nine amino acids in the CPUO patients compared to the control group and that the lower levels correlated with itch severity.
Previous animal studies have correlated low levels of these amino acids with itch symptoms in mice. These amino acids serve as building blocks for neurotransmitters that play a role in the body’s itch response and other allergic skin reactions. Providing mice with medications like antidepressants to boost neurotransmitters like serotonin was found to reduce itch symptoms.
“Many of these biomarkers that we found in depleted amounts in the blood of CPUO patients, like tryptophan and glycine, could contribute to the underlying pathogenesis of this condition, but we certainly need larger studies to investigate this further,” says Dr. Kwatra.
