Fig. 4. Blockage strategies to modulate inflammation.

In the middle stage of inflammation, immune cells are recruited to the inflammatory site, generating excessive pro-inflammatory cytokines and inducing severe inflammation. a | Anionic biomaterials, such as linear polymers, dendritic polymers and nanomaterials, can block the interaction between L-selectins on leukocytes and L-selectin ligands on the endothelium, or P-selectin on the endothelium and P-selectin ligands on leukocytes, to inhibit the migration of immune cells to the inflammation sites. b | Toll-like receptor (TLR) antagonists can be applied to block the activation of TLRs on immune cells to prevent the activation of immune cells.