Inulin- and Butyrate-Mediated HIF-1α Butyrylation Prevent Diabetic Ferroptosis and Cardiomyopathy by Maintaining Iron Homeostasis.

UNLABELLED: Abnormal iron metabolism and ferroptosis contribute to diabetic cardiomyopathy (DCM); however, the regulatory mechanisms remain unclear. Inulin improves systemic metabolism and cardiac function, but whether it alleviates myocardial ferroptosis and DCM is unknown. Using two distinct type 2 diabetes (T2D) mouse models-the high-fat diet combined with streptozotocin-induced T2D model and the db/db mouse model-in combination with an iron chelator, we found that imbalanced iron homeostasis and ferroptosis drive DCM. Inulin restored cardiac iron homeostasis, inhibited ferroptosis and DCM, and promoted short-chain fatty acids (SCFAs). Treatment with an SCFA inhibitor confirmed that SCFAs mediate the cardioprotective effects of inulin, with butyrate exerting the most potent antiferroptotic effect. Hypoxia-inducible factor 1α (HIF-1α) expression was decreased in DCM, and bioinformatic analysis identified HIF-1α as a hub gene in ferroptosis. Interference with HIF-1α in the two distinct T2D mouse models and in vitro weakened the antiferroptotic effect of butyrate. Mechanistically, butyrate inhibited HIF-1α ubiquitination by inducing HIF-1α butyrylation at lysine 190, which upregulated transcription of ferritin heavy chain (FTH) and mitochondrial ferritin (FTMT) to enhance the storage of unstable iron. HIF-1α acts as a critical regulator of myocardial iron homeostasis through transcriptional upregulation of FTH/FTMT. Inulin-fermented butyrate prevents ferroptosis-driven DCM, and its protective effect depends on the HIF-1α-FTH/FTMT axis via butyrylation. These findings highlight the therapeutic potential of using inulin or targeting HIF-1α in the management of DCM and diseases associated with aberrant iron metabolism.

ARTICLE HIGHLIGHTS: Dysregulated iron metabolism and ferroptosis contribute to diabetic cardiomyopathy (DCM); however, the regulatory mechanisms and effective therapeutic strategies remain elusive. We sought to identify the role of hypoxia-inducible factor 1α (HIF-1α) in regulating myocardial iron homeostasis and ferroptosis in DCM, as well as evaluate the preventive effects of inulin on ferroptosis-induced DCM and elucidate its mechanism. Inulin-fermented butyrate activates the HIF-1α-ferritin heavy chain (FTH)/mitochondrial ferritin (FTMT) axis, alleviating cardiac ferroptosis and DCM, and stabilizes HIF-1α by promoting K190 Kbu modification and inhibiting ubiquitin-dependent degradation. Targeting the HIF-1α-FTH/FTMT axis via inulin, butyrate, or alternative approaches may represent a promising therapeutic strategy for alleviating DCM and other diabetes complications.