Single local instillation of Staphylococcus aureus peptidoglycan prevents diabetes‐induced impaired wound healing

Abstract

Diabetes-induced impaired wound healing is characterized by inhibition of the inflammatory response to wounding, macrophage infiltration, angiogenesis, fibroplasia, reparative collagen accumulation, and wound breaking strength. Because all of these processes are accelerated in normal rats by a single local application at operation of Staphylococcus aureus peptidoglycan, we hypothesized that S. aureus peptidoglycan would prevent diabetes-induced impaired wound healing, despite persistent, untreated hyperglycemia, polydipsia, glycosuria, and polyuria. Sprague- Dawley male rats were divided into two groups. One group received an intraperitoneal injection of streptozotocin (65 mg/kg) in citrate solution; the other group received an intraperitoneal injection of an equivalent volume of citrate solution. Seventeen days after the injections, the diabetic and control rats received aseptically two 5.5-cm paravertebral incisions and subcutaneous implantation of six polyvinyl alcohol sponges, three on each side. On one side, each sponge contained 0.5 mg S. aureus peptidoglycan in 50 microliter saline solution, and the incision was inoculated along its length with 4.7 mg S. aureus peptidoglycan in 157 microliter saline solution (860 microgram/S. aureus peptidoglycan/cm incision); on the other side, the same respective volumes of saline were used. During the preoperative and postoperative periods, diabetic rats lost a small amount of weight (2%), were hyperglycemic (363 +/- 10 mg/100 ml blood), polydipsic, glycosuric, and polyuric, whereas the controls gained weight (25%) and were normoglycemic (104 +/- 5 mg/100 ml blood); these differences were significantly different (p <.001 in each case). In controls, S. aureus peptidoglycan inoculation increased wound breaking strength (by a factor of 2.0) and hydroxyproline content (by a factor of 1.4; p <.001 in each case); in diabetics, there were significant decreases in wound breaking strength (by a factor of 1.7) and hydroxyproline content (by a factor of 1.3) of saline solution-inoculated incisions and sponges compared with the wound breaking strength and hydroxyproline content of saline solution-inoculated incisions and sponges in controls (p <.02 and p <.001, respectively). These decreases were completely prevented when the incisions and polyvinyl alcohol sponges had been inoculated at operation with S. aureus peptidoglycan; S. aureus peptidoglycan inoculation in the diabetic rats increased wound breaking strength by a factor of 2.2 and sponge reparative tissue hydroxyproline by a factor of 1.6 (p <.001 in each case). Thus, diabetes-induced impaired wound healing was prevented completely by a single local instillation at operation of S. aureus peptidoglycan, despite persistent, untreated hyperglycemia, polydipsia, polyuria, and glycosuria.

Different Metabolism of Hexose Sugars and Sucrose in Wound Fluid and in Fibroblast Cultures Derived from Granulation Tissue, Hypertrophic Scar and Keloid

“…The control level of glucose in wound fluid seems to vary considerably. However, the concentration is always far beyond the normal blood glucose concentration in rats ranging from 4.1 to 6.5 mM [5][6][7]. Previously reported glucose concentrations in wound fluid have ranged from 2.8 to 5.0 mM [7,8].…”

Intracutaneous injection of the macrophage‐activating lipopeptide‐2 (MALP‐2) which accelerates wound healing in mice – a phase I trial in 12 patients

“…As expected, the TLR-2 ⁄ -6 agonist MALP-2 induced local erythema in all patients. We chose to perform our punch biopsies on day 7 and may have missed the optimal time point to detect leucocyte infiltration induced by MALP-2 (16)(17)(18)(19). In this study, stainings with monoclonal CD31 for endothelial cells, CD68 for macrophages and collagen IV revealed no differences between MALP-2-treated and control biopsies after 1 week.…”

“…Differences between MALP-2-treated wounds and vehicle controls became significant around day 10. We chose to perform our punch biopsies on day 7 and may have missed the optimal time point to detect leucocyte infiltration induced by MALP-2 (16)(17)(18)(19). Of note, after 1 week, untreated as well as treated wounds were almost healed in our patients.…”

“…MALP-2 signals via the toll-like receptors 2 and 6 (15,16) and stimulates a variety of cells other than macrophages (as the name would imply), among them mouse fibroblasts and human keratinocytes to produce growth factors and chemokines, e.g. Recruitment and stimulation of macrophages by various preparations have been shown to accelerate wound healing in different animal models (17)(18)(19). Recruitment and stimulation of macrophages by various preparations have been shown to accelerate wound healing in different animal models (17)(18)(19).…”

“…monocyte chemoattractant protein 1 (MCP-1), which again attracts macrophages to the wound site (16). Recruitment and stimulation of macrophages by various preparations have been shown to accelerate wound healing in different animal models (17)(18)(19). A secondary beneficial effect of MALP-2 in the context of wound healing may be attraction and stimulation of PMNs, which prevent infection and provide removal of wound debris.…”