Page 251 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

In ammatory response in a contaminated environment
Introduction
Meshes are occasionally used in a clean-contaminated or even in a contaminated environment, like fascial defects after bowel resection, near stomas or after removal of an infected mesh. Generally spoken, in clinical application the risk of complications like infection of the mesh is higher in a contaminated eld and therefore surgeons are hesitant to use meshes in these cases(1, 2). The extent of the in ammatory response of the body, also known as foreign body reaction, depends on the type and consistency of the mesh(3-5).
Using an in vitro model, we have recently described mesh-dependent reactions of macrophages in a contaminated environment(6). Many researchers investigate the foreign body reaction in a sterile environment. After implantation, all types of meshes used for abdominal wall hernia surgery induce a foreign body reaction. After implantation of the mesh, in ammatory cells, starting with neutrophils and mast cells are attracted to the wound site(3). Mast cells attract macrophages to the wound site and the number and degranulation of mast cells is important for the extend of the foreign body reaction. After implantation of the mesh, in ammatory cells, starting with neutrophils and mast cells are attracted to the wound site(3). Mast cells attract macrophages to the wound site and the number and degranulation of mast cells is important for the extend of the foreign body reaction(3, 4, 7, 8). Besides mast cells, T-cells are also important attractors of macrophages(3, 4, 9).
After being recruited, macrophages will dominate the wound site(3, 5). Macrophage phenotypes can range between pro-in ammatory (M1) and repair/anti-in ammatory (M2). M1-macrophages produce pro-in ammatory factors such as interleukin (IL)-6, tumor necrosis factor (TNF)α and express inducible nitric oxide synthase (iNOS)(10). M2-macrophages produce anti- in ammatory factors such as IL-1 receptor antagonist (IL-1RA), chemokines such as CCL18, and growth factors such as vascular endothelial growth factor (VEGF). M2-macrophages express among others the surface protein CD206, which is the mannose receptor important for recognition of pathogens(10).
How the foreign body reaction in a contaminated environment will depend on the type of material is not yet completely understood. In a contaminated environment, macrophages are expected to change mainly into the M1-phenotype because the infection and presence of bacteria needs to be eliminated(11). M1-macrophages negatively in uence incorporation of the
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