The conserved N-terminal histidine in an engineered peptide mediates sepsis treatment efficacy via dual binding to CD14 and LPS.

Sepsis remains a major clinical challenge due to the limited efficacy of existing therapies in controlling excessive inflammation. The engineered stapled peptide sHVF18, derived from an evolutionarily conserved thrombin innate fold, binds both lipopolysaccharide (LPS) and the LPS-binding groove of CD14, enabling dual targeting of bacterial components and host immune signaling. To define structural prerequisites for this dual action, we combined evolutionary analysis, in silico modeling, and experimental methods. Substituting the N-terminal histidine with lysine (K) or arginine (R) improved solubility, reduced aggregation, and enhanced interactions with LPS. However, unexpectedly, K-substitutions impaired CD14 binding, whereas R variants retained weaker affinity, possibly through cation-π interactions. The essential role of the evolutionarily conserved N-terminal histidine for CD14 interactions and therapeutic efficacy was demonstrated using LPS-induced shock and polymicrobial sepsis models. While the K variant exhibited superior efficacy in LPS-induced shock, its disrupted CD14 interactions rendered it ineffective in polymicrobial sepsis. In contrast, sHVF18, by engaging both LPS and CD14, effectively reduced inflammation and improved survival in polymicrobial sepsis. These findings highlight that targeting of both LPS and CD14 is essential for therapeutic efficacy, underscoring multivalency as a key principle for future sHVF18-based sepsis therapeutics.