hucMSC-Ex alleviates inflammatory bowel disease in mice by enhancing M2-type macrophage polarization via the METTL3-Slc37a2-YTHDF1 axis.

Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Ex) have emerged as a new treatment strategy for inflammatory bowel disease (IBD) due to their immunoregulatory function. N6-methyladenosine (m6A) plays a crucial role in regulating intestinal immunity, especially in IBD where macrophages play an important role, although its mechanism is not yet fully understood. From this perspective, this research aimed to evaluate the effect of hucMSC-Ex on m6A modification of macrophages in IBD. In the process of alleviating inflammation, hucMSC-Ex promotes macrophage polarization toward the M2 type and regulates intracellular m6A levels by upregulating the expression of m6A "Writer" METTL3 and "Reader" YTHDF1. Solute Carrier Family 37 Member 2 (Slc37a2) was identified by Methylation RNA immunoprecipitation sequencing as the target molecule of the hucMSC-Ex. Mechanically, hucMSC-Ex promoted the binding of METTL3 to the Slc37a2 mRNA complex, and enhanced the binding of Slc37a2 to YTHDF1 to upregulate the intracellular expression of Slc37a2, thereby attenuating the pro-inflammatory function of macrophage. This study confirms the modulatory role of hucMSC-Ex on the m6A modification of macrophages in IBD, providing a new scientific basis for the treatment of IBD with hucMSC-Ex.