In Vitro Inflammatory Response in Macrophages by Concentrated Surfactant Based Wound Dressings

Background: Despite inflammation playing an important role in the early stages of wound healing to help clear out damaged and dead cells along with microrganisms or foreign debris through the process of phagocytosis, excessive and non-resolving inflammation is one of the major factors which can ultimately result in the development of a chronic or non-healing wound and infection.

Purpose: In this study we examined the effect of concentrated surfactant based wound dressings on the lipopolysaccharide (LPS)-induced inflammatory response in human macrophage cell lines as an in vitro model.

Methods: Macrophage cells were cultured in RPMI 1640 medium supplemented with 1% Penicillin-streptomycin and 10% fetal bovine serum. Maturation of macrophage cells at 0.5 x 106/ml were induced with 100ng/ml PMA. After 24h with PMA, cells were further cultured for 48h in fresh complete medium. Cells were then treated with a concentrated surfactant gel preserved with antimicrobials (CSG) and a concentrated surfactant gel with 1% silver sulphadiazine (CSG-SSD) with or without LPS. The cells were incubated for 24h at 37C. The cell-free supernatants were collected and stored at -20C. The attached cells were then washed gently with PBS and stored at -80C until cell counting.  The cytokines, IL-1, IL-6, IL-10, TNFa and TGF-beta levels in supernatant were measured using enzyme-linked immunosorbent assays (ELISA). The cell viability of macrophages was counted using a commercially available CyQUANT cell proliferation assay.

Results: The number of attached macrophages decreased after treated with CSG-SSD but not with CSG. Treated with CSG and CSG-SSD did not generate significant levels of pro-inflammatory cytokines (IL-1, IL-6 and TNFa) compared to the negative control group after 24 hours. Compared to the CSG group, CSG-SSD decreased IL-1 and TNFa production after 96h.

Conclusion: The results showed that CSG-SSD is moderately cytotoxic to U937 macrophages. However, both CSG and CSG-SSD modulated the LPS-induced inflammatory response in macrophages.