CARD9-Mediated Macrophage Responses and Collagen Fiber Capsule Formation Caused by Textured Breast Implants

Background:An increasing number of women are undergoing breast implantation for cosmetic purposes or for reconstructive purposes after breast excision. The surface morphology of the breast implant is a key factor associated with the induction of capsule contraction. The effect of surface morphology on the inflammatory response after implant insertion remains unclear, however. The authors conducted comparative analyses to determine the effect of the textured and smooth surface morphology of silicone sheets.Methods:Each type of silicone sheet was inserted into the subcutaneous pocket below the panniculus carnosus in C57BL/6 mice and mice with genetic disruption of CARD9, Dectin-1, Dectin-2, or Mincle. The authors analyzed collagen fiber capsule thickness, histologic findings, and macrophage inflammatory response, including transforming growth factor (TGF)-beta synthesis.Results:The authors found that textured surface morphology contributed to the formation of collagen fiber capsules and the accumulation of fibroblasts and myofibroblasts, and was accompanied by the accumulation of TGF-beta-expressing macrophages and foreign-body giant cells. CARD9 deficiency attenuated collagen fiber capsule formation, macrophage responses, and TGF-beta synthesis, although the responsible C-type lectin receptors remain to be clarified.Conclusion:These results suggest that CARD9 may have a strong impact on silicone sheet morphology through the regulation of macrophage responses.Clinical Relevance Statement:Silicone breast implants have been widely used for postmastectomy and cosmetic augmentation mammaplasty breast reconstruction. The authors sought to elucidate the surface morphology of the breast implant as one of the key factors associated with the formation of collagen fiber capsules.CLINICAL QUESTION/LEVEL OF EVIDENCE:Therapeutic, V.