Dendritic Cell Repression by TNF-α-Primed Exosomes Accelerate T2DM Wound Healing Through miR-146a-5p/TXNIP/NLRP3 Axis.

Introduction: Type 2 diabetes mellitus (T2DM) impairs wound healing due to hyperglycemia-induced immune dysfunction. Dendritic cells (DCs) in the skin are crucial for wound healing but are adversely affected by hyperglycemic microenvironment. Exosomes derived from mesenchymal stem cells (MSC-exos), especially adipose-derived MSCs (ADSCs) with higher accessibility, have shown potential for immune regulation. However, their yield and efficacy can be limited. This study aims to explore the effects of TNF-α-preconditioned ADSCs-exos (T-exos) on restoring DC function and accelerating wound healing in T2DM.

Methods: T-exos were isolated from ADSCs pretreated with TNF-α. The regulatory effects of T-exos on DC immune responses under high glucose conditions were assessed. Subsequently, the roles of DCs treated with T-exos in diabetic wound healing were evaluated. Finally, the mechanism underlying T-exos-mediated regulation of DCs was investigated in detail.

Results: Under high glucose conditions, T-exos suppressed DC activation, as evidenced by reduced CD80/CD86 expression and NLRP3 inflammasome activity. In vivo studies showed that T-exos promoted wound closure in T2DM mice, enhancing collagen deposition, angiogenesis, and fibroblast proliferation. Mechanistically, TNF-α enriched miR-146a-5p in exosomes, which targeted TXNIP to inhibit NLRP3 inflammasome activation in DCs. Knockdown of miR-146a-5p abolished these effects in vitro and the therapeutic effect of T-exos on wound healing in vivo.

Conclusion: This study elucidates a previously unrecognized role for T-exos in effectively regulating DC activation through the miR-146a-5p/TXINP/NLRP3 axis, which in turn modulates the NLRP3 inflammasome pathway. By synergistically dampening inflammation and enhancing tissue repair, T-exos exhibit significant potential for clinical application in T2DM wounds.