Identification of a bilirubin receptor that may mediate a component of cholestatic itch
- Johns Hopkins School of Medicine, United States
Abstract
Various pathologic conditions result in jaundice, a yellowing of the skin due to a buildup of bilirubin. Patients with jaundice commonly report experiencing an intense non-histaminergic itch. Despite this association, the pruritogenic capacity of bilirubin itself has not been explored, and no bilirubin receptor has been identified. Here, we demonstrate that pathophysiologic levels of bilirubin excite peripheral itch sensory neurons and elicit pruritus through MRGPRs, a family of G-protein coupled receptors expressed in primary sensory neurons. Bilirubin binds and activates two MRGPRs, mouse MRGPRA1 and human MRGPRX4. In two mouse models of pathologic hyperbilirubinemia, we show that genetic deletion of either Mrgpra1 or Blvra, the gene that encodes the bilirubin-producing enzyme, attenuates itch. Similarly, plasma isolated from hyperbilirubinemic patients evoked itch in wild-type animals but not Mrgpra1-/- animals. Removing bilirubin decreased the pruritogenic capacity of patient plasma. Based on these data, targeting MRGPRs is a promising strategy for alleviating jaundice-associated itch.
Data availability
All data generated or analyzed during this study are included in the manuscript. Source data for main figures 1-7 have been provided.
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Author details
Funding
National Institute of Neurological Disorders and Stroke (R01NS054791)
- Xinzhong Dong
Howard Hughes Medical Institute
- Xinzhong Dong
National Institute of Mental Health (MH18501)
- Solomon H Snyder
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All experiments were performed in accordance with protocols approved by the Animal Care and Use Committee at the Johns Hopkins University School of Medicine. All animals were handled according to approved institutional animal care and use committee (IACUC) protocols (MO16M40) of Johns Hopkins University.
Copyright
© 2019, Meixiong et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Identification of a bilirubin receptor that may mediate a component of cholestatic itch
eLife 8:e44116.
https://doi.org/10.7554/eLife.44116
