IL17A and colitis: The results show that M2b macrophage‐derived exosomes greatly mitigate the severity of the induced colitis by upregulating levels of regulatory T cells (Treg) and IL‐4, and downregulating levels of the colitis‐associated cytokines (IL‐6,IL‐1β, and IL‐17A) via the C‐C motif chemokine ligand 1/8 (CCL1/CCR8) axis (Yang et al., 2019).