Background: Doxorubicin, a highly effective anthracycline used in cancer therapy, can lead to cardiotoxic induced cardiomyopathy. In preliminary in vitro experiments, we have found, that the expression of Guanylate-Binding Protein 5 (GBP5) in cardiomyocytes is upregulated after doxorubicin exposition. GBP5 plays a crucial role in the assembling of the NLRP3 inflammasome. However, the significance of GBP5 in inflammatory and structural myocardial damage during anthracycline-induced cardiotoxicity is not yet fully understood.
Methods: A conditional, cardiomyocyte-specific knock-in mouse model (GBP5-cKI) was generated, expressing a truncated, inactive form of GBP5 with a loss of the C-terminus of the protein. Wild-type and GBP5-cKI mice were treated with doxorubicin (3 mg/kg, i.p., 8 doses total) over 16 days. Four weeks after treatment completion, organs were harvested for further analysis. Cardiac function was assessed via echocardiography under anesthesia. Serum biomarkers, including cardiac troponin T, were measured, and survival was monitored. Molecular characterization was performed using qPCR and Western blot.
Results: GBP5-cKI mice exhibited a significantly higher survival rate following doxorubicin treatment compared to wild-type animals (p = 0.0004). Left ventricular function was largely preserved in the knock-in model, while it was impaired in wild-type mice (EF 51.2 ± 1.7% vs. 44.5 ± 2.2%, p = 0.0065; FS 26.1 ± 1.0% vs. 21.9 ± 1.3%, p = 0.0014). The release of cardiac injury markers was also reduced: Serum troponin T levels were lower in GBP5-cKI mice than in wild-type animals. On the RNA level, doxorubicin exposure led to a significant induction of cardiac stress and remodeling markers primarily in the wild-type group: Both Nppb (p < 0.05) and Nppa (p < 0.001) were markedly upregulated in WT hearts after treatment, while GBP5-cKI mice showed no comparable gene induction. The doxorubicin-induced upregulation of IL-1β was observed only in wild-type mice and was significantly attenuated in GBP5-cKI animals. Similarly, oxidative stress markers (XDH, NOX4) were significantly activated in WT mice but not in the knock-in model (both p < 0.05), confirming a reduced inflammatory-oxidative response in the GBP5-deficient myocardium.
Conclusion: Targeted inactivation of the C-terminal function of GBP5 provides protection against doxorubicin-induced myocardial damage. These findings highlight the role of GBP5 in regulating inflammatory response pathways in the heart and identify GBP5 as a promising therapeutic target for preventing anthracycline-associated cardiotoxicity.
