Effect of macrophage classical (M1) activation on implant‐adherent macrophage interactions withStaphylococcus epidermidis: A murinein vitromodel system

Abstract A modelin vitrosystem was developed for eliciting classical (M1) activation of surface‐adherent murine macrophages, which was then used to study the interaction of the M1 macrophages withStaphylococcus epidermidis. Glass substrata were first covalently grafted with a mixture of methoxy‐ and biotin‐terminated silanated polyethylene glycol. Interferon (IFN)‐γ and/or lipopolysaccharide (LPS), ligands known to induce the highly microbicidal M1 activation state in macrophages, were biotinylated and immobilized by way of a streptavidin intermediate to the biotin‐PEG base substratum. Assessment of mouse bone marrow‐derived macrophage (BMDM) interleukin (IL)‐12(p40) and nitric oxide response to the fabricated surfaces confirmed that the model system achieved activation of adherent macrophage: IFN‐γ‐presenting surfaces primed cells for M1 activation, LPS‐presenting surfaces elicited innate activation, and surface presenting a combination of IFN‐γ and LPS induced M1 activation. The phagocytic and microbicidal capacity of activated, surface‐adherent BMDM was evaluated usingS. epidermidis, a bacterial species prevalent in implant‐associated infections. Results indicate that M1 activation of implant‐adherent macrophages trends towards diminishing their phagocytic capacity, but enhances their microbicidal capacity forS. epidermidis. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.