VIP and rosacea: Recent studies have suggested that in rosacea lesions, neuronally expressed TRP channels, TLR2 and PAR2 might respond to the triggers, resulting in the release of neurovascular and neuro-immune active neuropeptides, such as PACAP, VIP, substance P, CGRP and so on, and eventually lead to flushing, erythema and inflammation5,6,20,53,54.