Polypropylene mesh implantation for hernia repair triggers myeloid cell-dependent persistent inflammatory foreign body reaction

Polypropylene meshes that are commonly used for surgical groin hernia repair may trigger granulomatous foreign body reactions. Here, we show that asymptomatic patients display mesh-associated inflammatory granulomas long after surgery, which are dominated by monocyte-derived macrophages. In mice, subdermal mesh implantation induces a rapid and strong myeloid cell accumulation, without substantial attenuation for up to 90 days. Myeloid cells segregate into distinct macrophage subsets with separate spatial distribution, activation profiles and functional properties. Protein mass spectrometry confirms the inflammatory nature of the foreign body reaction, as characterized by cytokines, complement activation and immunoglobulin deposition.