Synthetic antibacterial and anti-biofilm peptide (SAAP)-148 was developed to combat bacterial infections not effectively treatable with current antibiotics. SAAP-148 is highly effective against antimicrobial-resistant (AMR) bacteria without inducing resistance, however challenges for further development of SAAP-148 include its cytotoxicity and short circulation half-life. To circumvent these drawbacks a library of SAAP-148 linked to polyethylene glycol (PEG) groups of various lengths was screened for in vitro antibacterial activity and hemolytic activity. Results indicated that PEGylated SAAP-148 variants combine antibacterial activities with reduced hemolysis compared to SAAP-148. Interestingly, pro-inflammatory immunomodulatory activities of SAAP-148 were enhanced upon C-terminal PEGylation, with SAAP-148-PEG27 showing most effect. SAAP-148-PEG27 enhanced SAAP-148's capacity to chemoattract human neutrophils and was able to more efficiently (re)direct M-CSF-induced monocyte-macrophage differentiation towards type 1 macrophages compared to SAAP-148. Furthermore, dendritic cells with a stronger mature expression profile were produced if monocytes were exposed to SAAP-148-PEG27 during monocyte-immature dendritic cell differentiation in comparison to SAAP-148. Parameters that influenced the immunomodulatory activities of the peptide-PEG conjugate include i) the length of the PEG-group, ii) the position of PEG conjugation, and iii) the peptide sequence. Together, these results indicate that SAAP-148-PEG27 is highly effective in redirecting monocyte-macrophage differentiation towards a proinflammatory phenotype and promoting monocyte-mature dendritic cells development. Therefore, SAAP-148-PEG27 may be a promising agent to modulate inadequate immune responses in case of tumors and chronically infected wounds.

中文翻译：

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C 末端聚乙二醇化可提高 SAAP-148 肽的免疫调节活性。

合成抗菌和抗生物膜肽 (SAAP)-148 旨在对抗当前抗生素无法有效治疗的细菌感染。SAAP-148 对抗菌素耐药 (AMR) 细菌非常有效，且不会诱导耐药性，但 SAAP-148 进一步开发面临的挑战包括其细胞毒性和短循环半衰期。为了克服这些缺点，筛选了与不同长度的聚乙二醇（PEG）基团连接的SAAP-148文库的体外抗菌活性和溶血活性。结果表明，与 SAAP-148 相比，聚乙二醇化 SAAP-148 变体兼具抗菌活性和减少溶血作用。有趣的是，SAAP-148 的促炎免疫调节活性在 C 端聚乙二醇化后得到增强，其中 SAAP-148-PEG27 的效果最强。与 SAAP-148 相比，SAAP-148-PEG27 增强了 SAAP-148 趋化人类中性粒细胞的能力，并且能够更有效（重新）引导 M-CSF 诱导的单核细胞-巨噬细胞向 1 型巨噬细胞分化。此外，与 SAAP-148 相比，如果在单核细胞-未成熟树突细胞分化过程中将单核细胞暴露于 SAAP-148-PEG27，则会产生具有更强成熟表达谱的树突细胞。影响肽-PEG缀合物免疫调节活性的参数包括i) PEG基团的长度，ii) PEG缀合的位置，以及iii)肽序列。总之，这些结果表明 SAAP-148-PEG27 在将单核细胞-巨噬细胞分化转向促炎表型和促进单核细胞成熟树突状细胞发育方面非常有效。因此，SAAP-148-PEG27 可能是一种有前途的药物，可以在肿瘤和慢性感染伤口的情况下调节不充分的免疫反应。