Exosomal lncRNA TUG1 derived from BMSC ameliorate collagen-induced arthritis via BLIMP1-mediated Th17/Treg balance.

Background: Aberrant differentiation of Th17 cells has been identified as a critical factor in the development of rheumatoid arthritis (RA). BLIMP1 plays a key role in regulating plasma cell differentiation, T helper cell differentiation and Treg cell differentiation. Treatment with exosome injection or bone marrow mesenchymal stem cell (BMSC) transplantation reduce joint damage in RA. But the precise regulatory mechanisms remain unclear.

Methods: We injected BMSC-derived exosomes into RA mice, and then performed histological analysis on mouse ankle joints. We cultured CD4 T cells in vitro, then added exosomes with or without si-TUG1 and induced the differentiation of Th17 cells and Treg cells, and then we used flow cytometry to detect the ratio of Th17 cells and Treg cells. Furthermore, we injected exosomes into sh-NC or sh-BLIMP1-treated RA mice, and then performed histological analysis on the ankle joints.

Result: The results of our study demonstrate that exosome treatment decreased the proportion of differentiated Th17 cells, while increasing the proportion of Treg cells. And we observed that the Exo si-TUG1 group had an increased proportion of Th17 cells and a decreased proportion of Treg cells. We observed an increase in BLIMP1 expression in both the peripheral blood of mice and in CD4 T cells cultured in vitro in the Exo group. Conversely, the Exo si-TUG1 group showed a decrease in BLIMP1 expression. Notably, inhibiting BLIMP1 expression led to the reversal of the therapeutic effects of exosomes.

Conclusion: Our findings suggest that BMSC-derived exosomes promote the expression of BLIMP1 through Lnc TUG1-carrying exosomes, which may modulate the balance between Th17 cells and Treg cells. This mechanism ultimately alleviates damage caused by RA, suggesting that BMSC-derived exosomes enriched in Lnc TUG1 hold promise as a potential therapeutic approach for treating RA.