Shexiang Tongxin Dropping Pretreated Mesenchymal Stem Cells-derived Exosomes Attenuate Cardiac Ischemia/Reperfusion Injury by Modulating miR-182-5p and miR-199a-3p-mediated Inflammatory Responses

Background Previous research has highlighted the regulatory role of miR-182-5p in targeting TLR4 during the pathogenesis of allergic rhinitis. In a different context, TLR4 has been identified as a crucial factor in the development of lung ischemia-reperfusion injury, where its upregulation is believed to initiate the injury process. Additionally, miR-199a-3p has been shown to possess cardioprotective properties in simulated ischemia/reperfusion (I/R) injury models. Materials and Methods HE and TUNEL were performed to evaluate the cardiac injury and cellular apoptosis of I/R mice under distinct conditions. Real-time PCR was used to analyze the expression of microRNAs (miRNAs) and mRNAs under differential conditions. Results Pretreatment by Shexiang Tongxin Dropping (SXTXD) has been shown to significantly augment the therapeutic efficacy of MSC-derived exosomes (MSC-EXOs) in attenuating cardiac injury in I/R mice. MSC-EXOs effectively restored the repressed miR-182/miR-199a-3p expressions and activated TLR4/CD44 expressions in I/R mice, while SXTXD pretreatment remarkably strengthened the efficiency of MSC-EXOs. Moreover, SXTXD pretreatment notably reinforced the capability of MSC-EXOs to maintain cardiac parameters, including iNOS and interleukin-1β (IL-1β). Furthermore, the luciferase assay indicated that miR-182-5p and miR-199a-3p effectively suppressed the luciferase activities of TLR4 and CD44, respectively, through binding to the 3´ UTR. The overexpression of miR-182-5p and miR-199a-3p significantly suppressed the expression of TLR4 and CD44 in H2C6 and RAW264.7 cells. Conclusion In conclusion, our investigation indicates that MSC-derived exosomes, pretreated with SXTXD, hold promise in mitigating cardiac I/R injury by modulating inflammatory responses through the miR-182-5p/TLR4 axis and miR-199a-3p/CD44 axis. These findings suggest potential therapeutic strategies for addressing I/R-related cardiac complications.