Mature dendritic cells suppress tenocyte and fibroblast function via type I interferon signaling

Dendritic cells (DCs) play a critical role in modulating immune responses and tissue homeostasis. While immature DCs have been shown to enhance cell proliferation, the function of mature DCs (mDCs) in connective tissue biology remains less well understood. Here, we report that mDCs exert a potent inhibitory effect on tenocytes (TCs) and fibroblasts (FBs), suppressing both cell proliferation and type I collagen production. Using in vitro co-culture and supernatant transfer experiments, we demonstrate that this suppression is primarily mediated by soluble factors. Further mechanistic analysis revealed that type I interferons (IFN-α, IFN-β, IFN-ω), produced by mDCs upon LPS-induced maturation, are key mediators of these effects. Neutralization of the type I IFN signaling pathway restored both proliferation and collagen synthesis in TCs and FBs, confirming the central role of IFN signaling. Our findings suggest that mDCs may contribute to impaired tissue regeneration in inflammatory tendon pathologies.