Formononetin alleviates no reflow after myocardial ischemia-reperfusion via modulation of gut microbiota to inhibit inflammation.

Gut microflora plays an important role in relieving myocardial no-reflow (NR), formononetin (FMN) has potential effects on NR, however, the relationship between this effect and gut microflora remains unclear. This study aimed to evaluate the role of FMN in alleviating NR by regulating gut microflora. We used a myocardial NR rat model to confirm the effect and mechanism of action of FMN in alleviating NR. The rats were randomly divided into sham operation group (Sham), NR group, FMN group and sodium nitroprusside (SNP) group. Thioflavin S staining, Hematoxylin Eosin (HE), myocardial enzyme activity, ultrasonic cardiogram and RT-PCR detection showed that FMN could effectively reduce inflammatory cell infiltration, NR and ischemic area, improve cardiac structure and function and reduce TNF-α and NF-κB gene expression in NR rats. The results of 16S rRNA high-throughput sequencing showed that FMN could increase the abundance of anti-inflammatory bacteria such as Ligilactobacillus, Coprococcus, Blautia and Muribaculaceae and decrease the abundance of pro-inflammatory bacteria such as Treponema in Spirochaetota and Campylobacterota. The correlation between the differential bacteria in the gut microflora(anti-inflammatory bacteria and pro-inflammatory bacteria) and TNF-α and NF-κB, showed that they had a strong correlation. Therefore, the anti-NR mechanism of FMN may be related to increasing the abundance of anti-inflammatory bacteria and reducing the abundance of pro-inflammatory bacteria to inhibit inflammation. This study provides innovative mechanistic insights into the relationship between gut microbiota and myocardial protection, suggesting potential strategy for future treatment of NR.