We have revealed the dual role of the CCL2-CCR2 signaling pathway: on one hand facilitating headache chronification through enhancing both CGRP and PACAP signaling pathways in TG neurons [10], while on the other hand accelerating the resolution of chronic headache by LD-IL-2 through enhancing the infiltration/functionality of Treg cells. Here, CCL2 is linked to Headache.