Effects of Corticosteroid -mupirocin Cream on Interleukin-6 and Myeloperoxidase Levels in Infected Wounds of Male Wistar Rats

Abstract

Background: A wound is disruption of the normal architecture and function of any tissue. Wound infection results from microbial invasion of soft tissue and poses considerable clinical challenges including delayed healing and increased healthcare cost. It is also characterized by excessive inflammation and dysregulated levels of pro-inflammatory cytokines and proteases like interleukins and myeloperoxidases. The use of combined corticosteroids with antibiotics have been shown to modulate the level of cytokines and proteases with varying effects. Objectives: This study aimed to determine if there is a significant difference in the tissue level of Interleukin-6 and myeloperoxidase between control and experimental groups following the application of different combinations of corticosteroids-mupirocin topical agents on infected wounds in male Wistar rats. Methodology: An experimental study conducted among 42 male Wistar rats weighing 150-200g. They were randomly assigned into 7 groups of 6 rats each. Group 1 had no wound. A 2x2cm wound was made on the lower back of the rats in groups 2-7 using scalpel on Day 0 and the wounds were infected with Staphylococcus aureus and Pseudomonas aeruginosa on Day 3. On Day 5, Group 2 had wound dressed with only Vaseline gauze. Group 3 had wound dressed with Mupirocin ointment only. Group 4 had wound dressed with Mupirocin- Betamethasone combination (1:1). Group 5 had wound dressed with Mupirocin- Triamcinolone combination (1:1). Group 6 had wound dressed with Mupirocin- Betamethasone combination (2:1). Group 7 had wound dressed with Mupirocin-Triamcinolone combination (2:1). On the 25th day of the experiment, the rats were sacrificed through cervical dislocation. The wounds were excised and the homogenized tissues were assayed for interleukin- 6 and myeloperoxidase. Determination of the tissue interleukin-6 was done by sandwich-ELISA principle with the plate pre-coated with antibody specific for rat Interleukin-6 and the absorbance read at 450nm. Determination of myeloperoxidase was done by colorimetric principle and its activity was calculated indirectly by measuring the optical density value at 460nm. The data were analyzed using SPSS for Windows. Continuous variables were compared across groups using one-way analysis of variance (ANOVA) and the post-hoc test. ROC analysis to determine the sensitivity and specificity of the biochemical markers was done using MedCalc statistical software. The level of significance was set at p-value of < 0.05 Results: A decrease in the level of interleukin-6 was observed but was not significant (p=0.222) An increase in the level of myeloperoxidase observed was also not significant (p=0.738) when the treatment groups were compared with group 2 (the positive control). There was a negative correlation between interleukin 6 and wound infection on Day 10 of the experiment (r=-0.510 P=0.013) and a positive correlation between the myeloperoxidase level and wound infection on Day 10 (r=0.421 P=0.013). Myeloperoxidase ≤ 27.81 µmol/g had a sensitivity of 100%, a specificity of 53.85% while interleukin-6 >154.02 pg/mL had a sensitivity of 50%, a specificity of 88.46%. Comparison of the ROC curves however showed that myeloperoxidase is insignificantly more discriminant than IL-6 (P= 0.287). Conclusion: Corticosteroid-mupirocin cream combination increases myeloperoxidase and decreases interleukin-6 in rat wounds. Myeloperoxidase is a better marker to diagnose or monitor the resolution of wound infection compared with interleukin-6. Some insignificant changes observed may warrant further studies with larger sample size.