Intervertebral disc degeneration (IDD) is largely attributed to impaired endogenous repair. Nucleus pulposus-derived stem cells (NPSCs) senescence leads to endogenous repair failure. Small extracellular vesicles/exosomes derived from mesenchymal stem cells (mExo) have shown great therapeutic potential in IDD, while whether mExo could alleviate NPSCs senescence and its mechanisms remained unknown. We established a compression-induced NPSCs senescence model and rat IDD models to evaluate the therapeutic efficiency of mExo and investigate the mechanisms. We found that mExo significantly alleviated NPSCs senescence and promoted disc regeneration while knocking down thioredoxin (TXN) impaired the protective effects of mExo. TXN was bound to various endosomal sorting complex required for transport (ESCRT) proteins. Autocrine motility factor receptor (AMFR) mediated TXN K63 ubiquitination to promote the binding of TXN on ESCRT proteins and sorting of TXN into mExo. Knocking down exosomal TXN inhibited the transcriptional activity of nuclear factor erythroid 2-related factor 2 (NRF2) and activator protein 1 (AP-1). NRF2 and AP-1 inhibition reduced endogenous TXN production that was promoted by exosomal TXN. Inhibition of NRF2 in vivo diminished the anti-senescence and regenerative effects of mExo. Conclusively, AMFR-mediated TXN ubiquitination promoted the sorting of TXN into mExo, allowing exosomal TXN to promote endogenous TXN production in NPSCs via TXN/NRF2/AP-1 feed-forward circuit to alleviate NPSCs senescence and disc degeneration.

Objective To investigate the expression levels of secreted frizzled-related protein 5 (sFRP5), heat shock protein 60 (HSP60) and solute carrier family 16 member 11 (SLC16A11) in serum of patients with gestational diabetes mellitus (GDM) and their relationships with insulin resistance. Methods A total of 120 GDM patients in the hospital from January 2022 to December 2023 were selected as study group, and another 120 healthy pregnant women in the same period were selected as control group. The expression levels of serum sFRP5, HSP60 and SLC16A11 were detected; the levels of insulin resistance-related indicators[fasting blood glucose (FBG), fasting insulin (FINS), and homeostasis model assessment of insulin resistance (HOMA-IR)]were measured and calculated; the Pearson's correlation method was used to analyze the correlations of serum sFRP5, HSP60 and SLC16A11 with insulin resistance; the Logistic regression andysis and receiver operating characteristic (ROC) curve analysis were used to assess the relationships of serum sFRP5, HSP60 and SLC16A11 with GDM. Results The serum sFRP5 expression in the study group was significantly lower than that in the control group, while the serum HSP60, SLC16A11, FBG, FINS and HOMA-IR levels were significantly higher than those in the control group (P < 0.05). Pearson's correlation analysis showed that serum sFRP5 was negatively correlated with HSP60, SLC16A11, FBG, FINS and HOMA-IR (P < 0.05); serum HSP60 was positively correlated with SLC16A11, FBG, FINS and HOMA-IR (P < 0.05); serum SLC16A11 was positively correlated with FBG, FINS and HOMA-IR (P < 0.05). Multivariate Logistic regression analysis revealed that HSP60, SLC16A11, FBG, FINS and HOMA-IR were risk factors for GDM in pregnant patients, while sFRP5 was a protective factor (P < 0.05). The area under the curve (AUC) for the combined diagnosis of GDM in pregnant patients by serum sFRP5, HSP60 and SLC16A11 was 0.924, indicating that the combined diagnostic value of three indicators was superior to that of each individual indicator (all P < 0.05). Conclusion GDM patients exhibit decreased serum sFRP5 level and increased HSP60 and SLC16A11 levels; three indicators are factors influencing the occurrence of GDM in pregnant patients, and are associated with insulin resistance; the combination of three indicators exhibits high diagnostic efficacy for GDM.