Research ArticlePain

PIEZO2 mediates injury-induced tactile pain in mice and humans

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Science Translational Medicine  10 Oct 2018:
Vol. 10, Issue 462, eaat9892
DOI: 10.1126/scitranslmed.aat9892

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Understanding pain sensitization

Inflammation or nerve injury can alter tactile sensation, making a gentle touch perceived as painful. The molecular mechanisms mediating this alteration in sensation, called mechanical allodynia, are not completely understood. Murthy et al. and Szczot et al. found that PIEZO2 ion channels expressed in sensory neurons are required for the development of mechanical allodynia in mice and humans. The authors independently reached this conclusion using different animal models. Szczot et al. extended the discovery to humans, showing that PIEZO2 loss of function resulted in failure to develop mechanical allodynia. These two studies suggest that local inhibition of PIEZO2 ion channels might be effective for treating mechanical allodynia.

Abstract

Tissue injury and inflammation markedly alter touch perception, making normally innocuous sensations become intensely painful. Although this sensory distortion, known as tactile allodynia, is one of the most common types of pain, the mechanism by which gentle mechanical stimulation becomes unpleasant remains enigmatic. The stretch-gated ion channel PIEZO2 has been shown to mediate light touch, vibration detection, and proprioception. However, the role of this ion channel in nociception and pain has not been resolved. Here, we examined the importance of Piezo2 in the cellular representation of mechanosensation using in vivo imaging in mice. Piezo2-knockout neurons were completely insensitive to gentle dynamic touch but still responded robustly to noxious pinch. During inflammation and after injury, Piezo2 remained essential for detection of gentle mechanical stimuli. We hypothesized that loss of PIEZO2 might eliminate tactile allodynia in humans. Our results show that individuals with loss-of-function mutations in PIEZO2 completely failed to develop sensitization and painful reactions to touch after skin inflammation. These findings provide insight into the basis for tactile allodynia, identify the PIEZO2 mechanoreceptor as an essential mediator of touch under inflammatory conditions, and suggest that this ion channel might be targeted for treating tactile allodynia.

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