Histologic changes and gene expression patterns in biopsy specimens from bacteria-inoculated and noninoculated excisional body and limb wounds in horses healing by second intention.

This research explores how bacterial inoculation affects gene expression patterns and histologic changes when healing body and limb wounds in horses. The study discovered that bacterial inoculation generally did not significantly affect histologic scores and gene expression, except for interleukin-6 on day 27 and tumor necrosis factor-α on day 14.

Methodology

• The study involved wound biopsy specimens gathered from six horses on days 7, 14, 21, and 27 after excisional wounds were made over the metacarpal and metatarsal region and lateral thoracic region (body).
• Some of these wounds were inoculated on day 4 with bacteria.
• Specimens were examined and scored for inflammation, edema, angiogenesis, fibrosis organization, and epithelialization.
• Gene expression for ten markers associated with inflammation, proteolysis, fibrotic responses, and hypoxia was quantified via PCR assays.

Key Results

• Bacterial inoculation generally did not significantly impact histologic scores or gene expression, except for the gene expression of interleukin-6 on day 27 and tumor necrosis factor-α on day 14.
• Moreover, the gene expression of interleukin-1β, interleukin-6, serum amyloid A, and matrix metalloproteinase-9 was recorded higher in limb wounds than body wounds by day 27.
• The research also showed that the gene expression of Cellular Communication Network Factor 1 was higher in limb wounds than body wounds throughout the study period.

Conclusions

• The study found no clear infection markers, which reflects the challenges in detecting wound infections in horses.
• There were situational changes indicating prolonged inflammation in limb wounds. The gene expression patterns in limb wounds bore resemblance to chronic human wounds.
• Cellular Communication Network Factor 1’s role may be crucial for further studies and an understanding of the poor healing mechanism common in horse limb wounds.