CCL2 and allergic asthma: Given that M1 macrophages assemble a large number of pro-inflammatory Th1 cytokines (e.g. IL-6, IL-12, IL-1β, etc.)and chemokines (e.g. CCL2, CCL5, etc.), indicative of a leading function in the recruitment and activation of Th1 cells as well as clearance of intracellular pathogens, it has been referred to as the potential major effector in non-allergic asthma and associated with the pathophysiology of severe asthma, especially in those with a poor reaction to systemic corticosteroids 58, 59.