“AMP plus”: Immunostimulant-Inspired Design Based on Chemotactic Motif-(PhHAhPH)n

Ability to stimulate antimicrobial immunity has proven to be a useful therapeutic strategy in treating infections, especially in the face of increasing antibiotic resistance. Natural antimicrobial peptides (AMPs) exhibiting immunomodulatory functions normally encompass complex activities, which make it difficult to optimize their therapeutic benefits. Here, a chemotactic motif was harnessed as a template to design a series of AMPs with immunostimulatory activities plus bacteria-killing activities ("AMP plus"). An amphipathic peptide ((PhHAhPH)_n) was employed to improve the antimicrobial impact and expand the therapeutic potential of the chemotactic motif that lacked obvious bacteria-killing properties. A total of 18 peptides were designed and evaluated for their structure-activity relationships. Among the designed, KWH₂ (1) potently killed bacteria and exhibited a narrow antimicrobial spectrum against Gram-negative bacteria and (2) activated macrophages (i.e., inducing Ca²⁺ influx, cell migration, and reactive oxygen species production) as a macrophage chemoattractant. Membrane permeabilization is the major antimicrobial mechanism of KWH₂. Furthermore, the mouse subcutaneous abscess model supported the dual immunomodulatory and antimicrobial potential of KWH₂ in vivo. The above results confirmed the efficiency of KWH₂ in treating bacterial infection and provided a viable approach to develop immunomodulatory antimicrobial materials with desired properties.