Protease-activated receptor-2 in endosomes signals persistent pain of irritable bowel syndrome

Significance Activated G protein-coupled receptors (GPCRs) internalize and can continue to signal from endosomes. The contribution of endosomal signaling to human disease is unknown. Proteases that are generated in the colon of patients with irritable bowel syndrome (IBS) can cleave protease-activated receptor-2 (PAR 2 ) on nociceptors to cause pain. We evaluated whether PAR 2 generates signals in endosomes of nociceptors that mediate persistent hyperexcitability and pain. Biopsies of colonic mucosa from IBS patients released proteases that induced PAR 2 endocytosis, endosomal signaling, and persistent hyperexcitability of nociceptors. When conjugated to the transmembrane lipid cholestanol, PAR 2 antagonists accumulated in endosomes and suppressed persistent hyperexcitability. The results reveal the therapeutic potential of endosomally targeted PAR 2 antagonists for IBS pain, and expand the contribution of endosomal GPCR signaling to encompass processes that are relevant to disease.