Method development and characterization of the low molecular weight peptidome of human wound fluids

Wound infections are significant challenges globally, and there is an unmet need for better diagnosis of wound healing status and infection. The wound healing process is characterized by proteolytic events that are the result of basic physiological processes involving coagulation and complement activation, but also dysfunctional activations by endogenous and bacterial proteases. Peptides, downstream reporters of these proteolytic actions, could therefore serve as a promising tool for diagnosis of wound healing and infection. In the present study, we demonstrate a method for the characterisation of the complete peptidome of human wound fluids. We compare acute non-infected wound fluids obtained post-surgery with plasma samples and find significantly higher protein and peptide numbers in wound fluids, which typically were also smaller in size as compared to plasma-derived peptides. Finally, we analyse wound fluids collected from dressings after facial skin graft surgery and compare three uninfected and normally healing surgical wounds with three inflamed and S. aureus infected wounds. The results identify unique peptide patterns of various selected proteins including coagulation and complement factors, as well as proteases and antiproteinases. Together, the work defines a workflow for analysis of peptides derived from human wound fluids and demonstrate a proof-of-concept that such wound fluids can be used for analysis of qualitative differences of peptide patterns derived from wound fluids on larger patient cohorts, providing novel biomarkers for wound healing and infection.