In This Issue

Microbiota linked to chronic itchChronic itch, or pruritus, is a symptom of inflammatory skin conditions.The cause of chronic itch, which is difficult to treat, is unclear, but one hallmark of chronic itch is the overgrowth of sensory nerves in the skin.Jeremie Delaleu et al. investigated triggers and pathways of excess nerve growth in a mouse model of experimental psoriatic itch.Mice with previous exposure to Staphylococcus aureus exhibited more skin inflammation, increased itch, and nerve overgrowth, or hyperinnervation, compared with mice without S. aureus exposure.Using RNA sequencing, the authors found that inflammation, acting as part of an immune response to the skin microbiota, induces the IL-17A signaling pathway in sensory neurons.The signaling pathway is part of a regenerative transcriptional response in sensory nerves and associated with hyperinnervation.Together, the findings suggest that aberrant IL-17A signaling, as part of a maladaptive immune response to the skin microbiota, leads to the remodeling of skin sensory neurons that promotes nerve overgrowth and chronic itch.According to the authors, the findings suggest that the immune response to the skin microbiota may be a therapeutic target for chronic itch.-P.G.Chronic itch linked to skin microbiota.