A novel target for attenuating T1DM-induced myocardial ferroptosis

Abstract

Background: The DMCM-AHEAD trial showed that lipotoxicity is a distinct feature of diabetic heart failure, which initiates and exacerbates cardiac pathogenesis in diabetic patients. Circulating iron levels are increased in diabetic patients. The combined presence of lipids and iron suggests a predominant role of ferroptosis in diabetes-induced heart failure. However, molecular targets for diabetes-induced myocardial ferroptosis remain unclear. In the T1DM heart, matrix metalloproteinase-9 (MMP9), a protease, is upregulated, and targeted deletion of MMP9 is cardioprotective. Hypothesis: Targeted deletion of MMP9 mitigates T1DM-induced myocardial ferroptosis. Methods and results: We performed in vitro studies on the loss and gain-of-function of MMP9 using human cardiomyocytes (AC16 cells). Overexpression of MMP9 downregulates (-1.55-fold p<0.001) GPX4, a key marker of ferroptosis, while inhibition of MMP9 upregulates (+2.03-fold p<0.001) GPX4 (n=6), suggesting a key role of MMP9 in GPX4 regulation and ferroptosis signaling. To determine the specific role of MMP9 in T1DM-induced ferroptosis, we evaluated ferroptosis markers in the heart (LV) tissue of male Insulin2 mutant (Ins2+/-) Akita (T1DM), littermate euglycemic Ins2+/+ WT, Akita/MMP9 knockout (MMP9KO), and MMP9KO mice (n=3-6). The cardiac levels of Acyl-CoA synthetase long-chain family member-4 (ASCL4), which initiates the formation of lipid peroxides, and divalent metal transporter-1 (DMT1), which increases redox-active iron, were upregulated in the Akita while downregulated in the Akita/MMP9KO hearts (Akita vs WT: ASCL4: +1.42-fold p<0.05, DMT1: +1.34-fold p<0.05; Akita/MMP9 vs Akita: ACSL4: -1.46-fold p<0.05, DMT1: -1.03-fold p<0.05). Furthermore, cardiac levels of Ferritin-Light Chain (FLC), which stores iron to suppress ferroptosis, was downregulated in the Akita but upregulated in the Akita/MMP9KO hearts (Akita vs WT: -2.01-fold p<0.01, Akita/MMP9 vs Akita: +1.36-fold p<0.05). These results suggest that upregulation of MMP9 promotes while inhibition of MMP9 mitigates ferroptosis in the T1DM heart. Conclusion: This is the first report to reveal MMP9 as a promising therapeutic target for T1DM-induced myocardial ferroptosis. This work was supported in part by the National Institutes of Health (NIH) Grant R56HL156806 to PKM, and University of Nebraska Medical Center (UNMC) Presidential Graduate Fellowship to FIG. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.