This is further underlined by the bidirectional crosstalk between MCs and sensory neurons in AD pathology [95], while MRGPRX2 happens to be the major MC-expressed receptor for neuropeptides like SP, vasoactive intestinal peptide (VIP), somatostatin, cortistatin, and Pituitary adenylate cyclase-activating peptide (PACAP) [3,6]. This evidence concerns the gene TFF2 and Alzheimer disease.