Diabetic Kidney Disease Progression Alleviated in Mice by ALKBH5-Mediated UC-MSCs-Derived Exosomes That Inhibit TRAF6...

Diabetic kidney disease (DKD) is a major diabetes complication with limited treatment options. Exosomes (Exo) from umbilical cord mesenchymal stem cells (UC-MSCs) have shown therapeutic promise. The role of alkylation repair homologue protein 5 (ALKBH5)-modified UC-MSCs Exo in regulating macrophage polarisation and alleviating DKD is investigated.

DKD-associated inflammation was modelled by Lipopolysaccharide (LPS)/interferon-gamma (IFN-γ)-stimulated RAW264.7 macrophages. RT-qPCR and western blotting were employed to analyse mRNA and protein expression. Exosomes from ALKBH5-modified UC-MSCs were isolated and characterised. Macrophage polarisation (M1/M2) was assessed by flow cytometry, RT-qPCR, and enzyme-linked immunosorbent assay (ELISA). Tumor necrosis factor receptor-associated factor 6 (TRAF6) N6-methyladenosine (m6A) modification and expression were analysed via methylated RNA immunoprecipitation (MeRIP) and RNA immunoprecipitation (RIP) assays. The DKD model was established using spontaneous diabetic db/db mice. The renal function of mice was evaluated by ELISA and commercial assay kits. Hematoxylin-eosin (HE), periodic acid-Schiff (PAS), and Masson's trichrome staining were performed to assess the renal histopathology of mice.

ALKBH5 overexpression promoted M2 and inhibited M1 macrophage polarisation. ALKBH5 downregulated TRAF6 via m6A demethylation. ALKBH5-modified UC-MSCs Exo enhanced M2 polarisation and suppressed M1 phenotype in vitro. In DKD mice, ALKBH5-modified UC-MSCs Exo mitigated renal injury. Moreover, these exosomes enhanced anti-inflammatory responses and promoted M2 macrophage polarisation in DKD mice.

ALKBH5-modified UC-MSCs Exo reduced TRAF6 expression by demethylating its m6A sites, promoting M2 macrophage polarisation and alleviating DKD progression. These findings suggested that ALKBH5-modified UC-MSCs Exo might represent a promising therapeutic approach for DKD.