Temporal Dynamics and Interrelations of Cytokines, Neutrophil Proteins, Exudation, and Bacterial Colonization in Epidermal Wound Healing

Abstract Inflammation is integral to wound healing, yet its dynamics in normally healing epidermal wounds are not fully characterized. To this end, we analyzed longitudinal wound fluid samples collected from epidermal suction blister wounds in healthy volunteers. Cytokine levels peaked on day 5, followed by a decline on day 8. Wound exudation, measured by protein content, increased from day 2, peaking on day 5. The neutrophil-derived proteins myeloperoxidase, elastase, and heparin binding protein (HBP) peaked on day 5, correlating with interleukin (IL)-8, a key neutrophil chemoattractant. With a focus on viable cultivable wound bacteria, aerobic species were cultured from wound swabs and dressings and identified by MALDI-TOF mass spectrometry. The identified bacteria consisted primarily of commensal bacteria, including various staphylococci. Levels of such bacteria rose from day 2, peaking on days 5-8, and aligned with increases in the cytokines tumor necrosis factor (TNF)-α, IL-1β and IL-10 at the peak of inflammation on day 5. The study uncovers the coordinated dynamics of cytokines, neutrophil activity, and major commensal bacteria in epidermal wound healing, and identifies HBP – a marker for neutrophil activation and endothelial leakage – for the first time in normally healing epidermal wounds. The clinical study in which the analyzed samples were collected is registered in clinicaltrials.gov ( NCT05378997 ).