An inflammatory soup: proteomic analysis of chronic wounds

In contrast to normal-healing wounds, chronic wounds commonly show disturbances in proteins regulating wound healing processes, particularly those involved in cell proliferation and protein degradation. MudPIT-MS/MS was conducted to investigate and compare the protein composition of chronic diabetic foot exudates to exudates from split-skin donor sides of burn victims otherwise healthy. Spectral counting revealed 188 proteins differentially expressed (>2-fold and p-value <0.05) in chronic wounds. Most involved in biological processes including inflammation, angiogenesis and cell mortality. Increased expression of the inflammatory response stimulating S100 proteins, predominantly S100A8 and S100A9 (almost 10-fold), were identified. Matrix metalloproteinases MMP1, MMP2 and MMP8 were identified to be elevated in chronic wounds with significant impact on collagen degradation and tissue destruction. Further, proteins with anti-angiogenic properties were found at higher expression levels in chronic wounds. Reduced angiogenesis leads to drastic shortage in nutrition supply and cause increased cell death, demonstrated by Annexin A5 exclusively found in chronic wound exudates. However, excessive nucleic and cytosolic material infers cell death not only occurring by apoptosis but also by necrosis. In conclusion, mass spectrometric investigation of exudates from chronic wounds demonstrated dramatic impairment in wound repair with excessive inflammation, anti-angiogenic environment, and accelerated cell death.

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