Macrophages activate Th1 and Th17 cells with subsequent neutrophilic inflammation [77], and the release of IL-17, IL-21, and IL-IL-17 is responsible for the recruitment of neutrophils and is associated with airway hyperreactivity (AHR), severe asthma and corticosteroid resistance [17,78,79,80,81]. Here, IL17A is linked to asthma.