Crocin inhibits KBTBD7 to prevent excessive inflammation and cardiac dysfunction following myocardial infarction

Myocardial infarction (MI) refers to myocardial ischemic necrosis that is caused by coronary artery disease. Notably, crocin has protective effects on the heart. The present study aimed to i) investigate the protective effect of crocin, an active ingredient in Gardenia jasminoides Ellis and Crocus sativus L., on myocardial ischemia and ii) to verify the interaction between crocin and kelch repeat and BTB domain‑containing protein 7 (KBTBD7), which is a novel member of the BTB‑kelch protein family. In the present study, the left anterior descending coronary artery was ligated to establish a myocardial ischemia‑reperfusion injury (MIRI) model in rats and the protective effect of crocin on rat myocardial tissue was observed. The levels of the inflammatory cytokines, interleukin (IL)‑1β, IL‑6 and tumor necrosis factor α (TNFα), in the sham, MI model, MI + crocin (100 mg/kg) and MI + crocin (200 mg/kg) groups were compared in the rat myocardial tissue. The TUNEL assay was used to detect apoptosis of myocardial cells. In addition, RAW264.7 cells were stimulated with the inflammatory factors recombinant mouse high mobility group box 1 (rmHMGB1) and recombinant mouse heat shock protein 60 (rmHSP60). The inhibitory effect of crocin on inflammatory cytokine levels was observed using ELISA. Western blotting was used to detect the inhibitory effect of crocin on KBTBD7. The inhibitory effect of KBTBD7 knockdown on MAPK and nuclear factor (NF)‑κB signaling pathways was also analyzed. The expression levels of IL‑1β, IL‑6 and TNFα were significantly decreased in the crocin‑treated groups compared with in the model group. Crocin significantly reduced the apoptosis of myocardial cells and significantly inhibited the release of inflammatory cytokines induced by rmHMGB1 and rmHSP60. KBTBD7 was determined to be a target of crocin. Knockdown of KBTBD7 significantly inhibited p38 and NF‑κB signaling pathways. Furthermore, the results demonstrated that KBTBD7 knockdown significantly reduced the production of inflammatory cytokines induced by rmHMGB1 and rmHSP60. KBTBD7 knockdown also significantly reduced p38 and NF‑κB signaling in the rmHMGB1‑ and rmHSP60‑treated groups. The present study demonstrated the potential protective effect of crocin on MIRI in rats. The underlying mechanism may be through direct inhibition of KBTBD7, thereby inhibiting excessive inflammatory responses and myocardial cell apoptosis following myocardial infarction.