CARD9-mediated macrophage responses and collagen fiber capsule formation caused by textured-type breast implants.

BACKGROUND: An increasing number of women are undergoing breast implantation for cosmetic purposes and for reconstructive purposes after breast excision. The surface morphology of the breast implant is one of the key factors associated with the induction of capsule contraction. The effect of surface morphology on the inflammatory response following implant insertion remains unclear, however. This study 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. We also analyzed the collagen fiber capsule thickness, histological findings, and macrophage inflammatory response, including TGF-ß synthesis. RESULTS: We 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-ß-expressing macrophages and foreign-body giant cells. CARD9 deficiency attenuated collagen fiber capsule formation, macrophage responses, and TGF-ß synthesis, although the responsible C-type lectin receptors (CLRs) remain to be clarified. CONCLUSIONS: These results suggest that CARD9 may have a strong impact on silicone sheet insertion through the regulation of macrophage responses.

Cutaneous wound healing promoted by topical administration of heat-killed Lactobacillus plantarum KB131 and possible contribution of CARD9-mediated signaling.

Optimal conditions for wound healing require a smooth transition from the early stage of inflammation to proliferation, and during this time alternatively activated (M2) macrophages play a central role. Recently, heat-killed lactic acid bacteria (LAB), such as Lactobacillus plantarum (L. plantarum) have been reported as possible modulators affecting the immune responses in wound healing. However, how signaling molecules regulate this process after the administration of heat-killed LAB remains unclear. In this study, we examined the effect of heat-killed L. plantarum KB131 (KB131) administration on wound healing and the contribution of CARD9, which is an essential signaling adaptor molecule for NF-kB activation upon triggering through C-type lectin receptors, in the effects of this bacterium. We analyzed wound closure, histological findings, and inflammatory responses. We found that administration of KB131 accelerated wound closure, re-epithelialization, granulation area, CD31-positive vessels, and α-SMA-positive myofibroblast accumulated area, as well as the local infiltration of leukocytes. In particular, M2 macrophages were increased, in parallel with CCL5 synthesis. The acceleration of wound healing responses by KB131 was canceled in CARD9-knockout mice. These results indicate that the topical administration of KB131 accelerates wound healing, accompanying increased M2 macrophages, which suggests that CARD9 may be involved in these responses.

Distinct Roles for Dectin-1 and Dectin-2 in Skin Wound Healing and Neutrophilic Inflammatory Responses.

C-type lectin receptors recognize microbial polysaccharides. The C-type lectin receptors such as dendritic cell-associated C-type lectin (Dectin)-1 and Dectin-2, which are triggered by ß-glucan and α-mannan, respectively, contribute to upregulation of the inflammatory response. Recently, we demonstrated that activation of the Dectin-2 signal delayed wound healing; in previous studies, triggering the Dectin-1 signal promoted this response. However, the precise roles of these C-type lectin receptors in skin wound healing remain unclear. This study was conducted to determine the roles of Dectin-1 and Dectin-2 in skin wound healing, with a particular focus on the kinetics of neutrophilic inflammatory response. Full-thickness wounds were created on the backs of C57BL/6 mice, and the effects of Dectin-1 or Dectin-2 deficiency and those of ß-glucan or α-mannan administration were examined. We also analyzed wound closure, histological findings, and neutrophilic inflammatory response, including neutrophil extracellular trap formation at the wound sites. We found that Dectin-1 contributed to the acceleration of wound healing by inducing early-phase neutrophil accumulation, whereas Dectin-2 was involved in prolonged neutrophilic responses and neutrophil extracellular trap formation, leading to delayed wound healing. Dectin-2 deficiency also improved collagen deposition and TGF-ß1 expression. These results suggest that Dectin-1 and Dectin-2 have different roles in wound healing through their different effects on the neutrophilic response.