Anti-Bacterial Effects of Poly-N-Acetyl-Glucosamine Nanofibers in Cutaneous Wound Healing: Requirement for Akt1

作者：Lindner Haley Buff^*; Zhang Aiguo; Eldridge Juanita; Demcheva Marina; Tsichilis Philip; Seth Arun; Vournakis John; Muise Helmericks Robin C

来源：PLos One, 2011, 6(4): e18996.

DOI：10.1371/journal.pone.0018996

Background: Treatment of cutaneous wounds with poly-N-acetyl-glucosamine nanofibers (sNAG) results in increased kinetics of wound closure in diabetic animal models, which is due in part to increased expression of several cytokines, growth factors, and innate immune activation. Defensins are also important for wound healing and anti-microbial activities. Therefore, we tested whether sNAG nanofibers induce defensin expression resulting in bacterial clearance.
Methodology: The role of sNAG in defensin expression was examined using immunofluoresence microscopy, pharmacological inhibition, and shRNA knockdown in vitro. The ability of sNAG treatment to induce defensin expression and bacterial clearance in WT and AKT1(-/-) mice was carried out using immunofluoresent microscopy and tissue gram staining. Neutralization, using an antibody directed against beta-defensin 3, was utilized to determine if the antimicrobial properties of sNAG are dependent on the induction of defensin expression.
Conclusions/Findings: sNAG treatment causes increased expression of both alpha- and beta-type defensins in endothelial cells and beta-type defensins in keratinocytes. Pharmacological inhibition and shRNA knockdown implicates Akt1 in sNAG-dependent defensin expression in vitro, an activity also shown in an in vivo wound healing model. Importantly, sNAG treatment results in increased kinetics of wound closure in wild type animals. sNAG treatment decreases bacterial infection of cutaneous wounds infected with Staphylococcus aureus in wild type control animals but not in similarly treated Akt1 null animals. Furthermore, sNAG treatment of S. aureus infected wounds show an increased expression of beta-defensin 3 which is required for sNAG-dependent bacterial clearance. Our findings suggest that Akt1 is involved in the regulation of defensin expression and the innate immune response important for bacterial clearance. Moreover, these findings support the use of sNAG nanofibers as a novel method for enhancing wound closure while simultaneously decreasing wound infection.

• 出版日期2011-4-29