Two distinct clusters of patients with prurigo nodularis (PN) have been identified, and these clusters have noninflammatory and inflammatory plasma profiles, according to a study published online Oct. 27 in the Journal of Investigative Dermatology.

Nishadh Sutaria, from the Johns Hopkins University School of Medicine in Baltimore, and colleagues assayed circulating plasma cytokine concentrations in 20 PN patients and matched healthy controls and used an unsupervised machine learning algorithm to identify disease endotypes.

The researchers identified two distinct clusters of PN patients with noninflammatory and inflammatory plasma profiles (cluster 1 and cluster 2, respectively). More African Americans were seen in cluster 2 (82 versus 9 percent), which also had higher worst-itch numeric rating scale scores (9.5 ± 0.9 versus 8.3 ± 1.2) and higher Dermatology Life Quality Index scores, indicating lower quality of life (21.9 ± 6.4 versus 13.0 ± 4.1). A higher rate of myelopathy was seen in cluster 1 (67 versus 18 percent). Cluster 2 had higher levels of interleukin (IL)-1α, IL-4, IL-5, IL-6, IL-10, IL-17A, IL-22, IL-25, and interferon-α. Compared with Caucasian PN patients, African American PN patients had a higher erythrocyte sedimentation rate, C-reactive protein, ferritin, and eosinophils and lower transferrin.

"These findings highlight significant disease heterogeneity, implicating that there are distinct endotypes in PN that may enable precision medicine approaches to the treatment of PN," the authors write.

One author disclosed financial ties to the biopharmaceutical industry.

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