Previous studies have shown upregulation of NGF at sites of tissue inflammation (9, 10), changes in its expression in the urine and bladders of both rodents and humans with cystitis (11–14), and changes in bladder function consistent with cystitis as a consequence of its urothelial overexpression (15, 16) or administration to the bladder (17, 18). Here, NGF is linked to chronic cystitis.