**4. Conclusions**

Two conjugated derivatives of the antimicrobial HDP IDR1018 were designed based on N-terminal pegylation and glycosylation, in order to improve the biocompatibility and biological properties of the original peptide sequence. While additional studies remain to be explored, such as using different sugar moieties, different lengths of PEG chains, and different ligation approaches, the current conjugates significantly reduced the aggregation, hemolysis, and cytotoxicity of the parent peptide. Moreover, while pegylation conserved the immunomodulatory properties of the peptide, glycosylation generated a superior immunomodulating conjugate with a strong ability to stimulate the release of chemokine MCP-1 and the anti-inflammatory cytokine IL-1RA while suppressing the LPSinduced production of proinflammatory cytokines TNFα and IL-1β, suggesting a novel anti-inflammatory drug candidate. Consistent with several previously reported studies, both conjugations led to partial reductions in antimicrobial as well as antibiofilm activity cf. the original IDR1018. Overall, the study reported here clearly demonstrates the usefulness of these conjugation approaches in optimizing the physicochemical properties of therapeutic peptides and highlight a new potential opportunity for enhancing immunomodulatory HDPs through glycosylation.

**Author Contributions:** Methodology, H.E.; Formal analysis, F.Y.; Investigation, H.E. and F.Y.; Writing—original draft, H.E.; Writing—review & editing, H.E. and R.E.W.H.; Supervision, H.E. and R.E.W.H.; Project administration, R.E.W.H.; Funding acquisition, R.E.W.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Canadian Institutes for Health Research (CIHR) Foundation grant (FDN-154287). H.E. is the recipient of the Michael Smith Health BC Research Fellowship. R.E.W.H. holds a UBC Killam Professorship.

**Institutional Review Board Statement:** All experiments performed on human blood adhered to the Declaration of Helsinki and approved by the Institutional Review Board and Ethics Committee of the University of British Columbia, Vancouver, BC, Canada (protocol code H-2100727 and date of approval 7 January 2022).

**Informed Consent Statement:** In all experiments involved human samples, informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The parent peptide IDR-1018 has been filed by the University of British Columbia for patent protection with REWH as an inventor and is the subject of several issued patents US Patent US8343475, New Zealand patent 574758, Australian Patent 2007288080, European patent EP2061886, Denmark patent #2061886, Spain patent 2061886, and Canadian patent 2,660,668. It has been licensed to ABT Innovations Inc., in which REWH has shares. The other authors declare no conflict of interest.
