Mitochondrial Transplantation Suppresses mtDNA-cGAS/STING-Mediated Innate Immunity by Enhancing PINK1/Parkin-Dependent Mitophagy to Attenuate Keloid Fibrosis

Abstract

Keloids are characterized by fibrosis and chronic inflammation, but links between mitochondrial dysfunction and keloid pathogenesis remain unclear. This study examined whether impaired PINK1/Parkin-dependent mitophagy is associated with mitochondrial DNA (mtDNA)-mediated innate immune activation and fibrosis in keloids, and evaluated mitochondrial transplantation as a potential therapeutic strategy. Primary keloid fibroblasts (KFs), normal skin fibroblasts (NFs), adipose-derived stem cells (ADSCs), human keloid tissues, and human keloid xenografts in immunodeficient BALB/c nude mice were analyzed using ultrastructural, molecular, and functional approaches. Freshly isolated NF-derived mitochondria (nMito) and ADSC-derived mitochondria (aMito) were compared at protein-equivalent doses. KFs exhibited mitochondrial abnormalities, impaired oxidative phosphorylation, increased reactive oxygen species, mtDNA leakage, and cGAS/STING pathway activation. Elevated PINK1 expression, reduced Parkin expression and p62 accumulation were consistent with impaired downstream mitophagic clearance. Both nMito and aMito were associated with improved mitochondrial function, changes in mitophagy-related markers, reduced cytosolic mtDNA and cGAS/STING signaling, and attenuated fibroblast activation, with greater aMito-associated changes in selected endpoints. In xenografts, intralesional administration of either mitochondria improved collagen organization and reduced fibrotic and inflammatory signaling. Together, these findings link altered PINK1/Parkin-dependent mitophagy to mtDNA-driven inflammation and fibrosis and support mitochondrial transplantation as a potential organelle-based therapeutic approach.