Pseudomonas aeruginosa biofilm aggravates skin inflammatory response in BALB/c mice in a novel chronic wound model

• Published in: Wound repair and regeneration 2013-03, Vol.21 (2), p.292-299
• Main Authors: Trøstrup, Hannah, Thomsen, Kim, Christophersen, Lars J., Hougen, Hans P., Bjarnsholt, Thomas, Jensen, Peter Ø., Kirkby, Nikolai, Calum, Henrik, Høiby, Niels, Moser, Claus
• Format: Article
• Language: English
• Subjects: Alginates - pharmacology; Animals; Anti-Infective Agents - pharmacology; Biofilms - drug effects; Burns - drug therapy; Burns - pathology; Burns - physiopathology; Chronic Disease; Disease Models, Animal; Female; Interleukin-1beta - metabolism; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Pseudomonas Infections - drug therapy; Pseudomonas Infections - pathology; Pseudomonas Infections - physiopathology; Skin - pathology; Skin - physiopathology; Wound Healing; Wound Infection - drug therapy; Wound Infection - immunology; Wound Infection - pathology; Wound Infection - physiopathology
• ISSN: 1067-1927; 1524-475X
• DOI: 10.1111/wrr.12016

Chronic wounds are presumed to persist in the inflammatory state, preventing healing. Emerging evidence indicates a clinical impact of bacterial biofilms in soft tissues, including Pseudomonas aeruginosa (PA) biofilms. To further investigate this, we developed a chronic PA biofilm wound infection model in C3H/HeN and BALB/c mice. The chronic wound was established by an injection of seaweed alginate‐embedded P. aeruginosa PAO1 beneath a third‐degree thermal lesion providing full thickness skin necrosis, as in human chronic wounds. Cultures revealed growth of PA, and both alginate with or without PAO1 generated a polymorphonuclear‐dominated inflammation early after infection. However, both at days 4 and 7, there were a more acute polymorphonuclear‐dominated and higher degree of inflammation in the PAO1 containing group (p < 0.05). Furthermore, PNA‐FISH and supplemented DAPI staining showed bacteria organized in clusters, resembling biofilms, and inflammation located adjacent to the PA. The chronic wound infection showed a higher number of PAO1 in the BALB/c mice at day 4 after infection as compared to C3H/HeN mice (p < 0.006). In addition, a higher concentration of interleukin‐1beta in the chronic wounds of BALB/c mice was observed at day 7 (p < 0.02), despite a similar number of bacteria in the two mouse strains. The present study succeeded in establishing a chronic PA biofilm infection in mice. The results showed an aggravating impact of local inflammation induced by PA biofilms. In conclusion, our findings indicate that improved infection control of chronic wounds reduces the inflammatory response and may improve healing.