Scratching promotes allergic inflammation and host defense via neurogenic mast cell activation

DOI: 10.1126/science.adn9390

Key points:

1. The Itch-Scratch Paradox

• Scratching is an evolutionarily conserved behavior but seems counterproductive as it worsens inflammation
• Research found scratching serves both harmful and beneficial purposes:
  • Can exacerbate allergic skin conditions
  • Helps protect against bacterial infections like S. aureus
  • Provides insight into why scratching is pleasurable despite negative effects

2. The Mechanism:

• When scratching occurs:
  1. Activates pain-sensing neurons (nociceptors) in the skin
  2. Nociceptors release substance P (a neuropeptide)
  3. Substance P activates ma ...