hucMSC-derived exosomes targeting macrophage polarization attenuate systemic inflammation in T1DM via INS/SOD1 delivery.

Background: Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by absolute insulin (INS) deficiency. As key components of the immune system, macrophages play critical roles in T1DM-associated pancreatic β-cell damage and multiorgan inflammatory injuries. Exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-EXOs) have emerged as promising therapeutic agents for immune-related disorders due to their immunomodulatory properties and favorable safety profile. However, systematic investigations into the therapeutic potential of hucMSC-EXOs in T1DM are lacking. This study aimed to evaluate the systemic anti-inflammatory effects of hucMSC-EXOs in T1DM and identify their key bioactive components.

Methods: T1DM was induced in C57BL/6 male mice via streptozotocin, followed by intraperitoneal administration of hucMSC-EXOs. Systemic glucose metabolism, multiorgan pathology, and macrophage infiltration were assessed. In vitro, THP-1-derived macrophages were polarized to an M1 phenotype and treated with hucMSC-EXOs. Proteomic profiling, pharmacological inhibition, and functional assays were employed to identify critical exosomal components.

Results: hucMSC-EXOs significantly reduced hyperglycemia, restored glucose tolerance, and attenuated structural damage in the pancreas, spleen, liver, kidney, and heart of T1DM mice (p < 0.05). Mechanistically, hucMSC-EXOs suppressed macrophage infiltration and proinflammatory cytokine secretion (IL-6, TNF-α, CCL-2) across tissues. Proteomic analysis revealed INS and superoxide dismutase 1 (SOD1) as enriched anti-inflammatory proteins in hucMSC-EXOs. Heat inactivation abolished their bioactivity, while pharmacological inhibition of INS (S961) or SOD1 (ATN-224) reversed hucMSC-EXOs-mediated suppression of macrophage activation (p < 0.01).

Conclusions: This study demonstrates that hucMSC-EXOs ameliorate T1DM- associated hyperglycemia and multiorgan inflammation by targeting macrophage polarization through delivery of INS and SOD1. Our study reveals that hucMSC-EXOs exert their anti-inflammatory effects through coordinated delivery of insulin and SOD1, establishing a protein-centric mechanism for exosome-mediated immunomodulation in T1DM.